Laurence Viale

Stéphano Vacher

Jeanne Bessouat

Eco-innovation in the upstream supply chain: re-thinking the involvement of purchasing managers

Keywords: Eco-innovation, Ecological transition, Purchasing management, RBV, Stakeholder theory Classification: Research paper

Purpose: In a context of ecological transition, this study aims to explore and understand what fosters the participation of purchasing departments and identify the drivers and difficulties encountered during the development of eco-innovation within firms.

Design/Methodology/Approach: We adopt a qualitative methodology that provides tools to study complex phenomena. In-depth interviews with highly knowledgeable respondents from multisectoral organisations enable us to explore the eco-innovation process within firms.

Findings: From the perspectives of resource-based theory and stakeholder theory, the study contributes to the literature by investigating firms' internal resources and exploring further dimensions based on sustainable SCM and purchasing. Internal stakeholders (e.g., purchasing agents) and external stakeholders (e.g., suppliers) were identified with regard to the business eco-innovation activities of focal companies in relation to upstream stakeholders. We examine this complex phenomenon by raising certain intra-and inter-organisational factors, as well as more individual aspects, such as the sensitivity of the purchasing manager to ecological transition. Purchasing agents are involved in increasing the propensity of organisations to eco-innovate and, as internal stakeholders, appear to be influential in ecoinnovation.

Originality:

The study provides new insights into the constituent resources needed for purchasing participation during eco-innovation in order to achieve sustainable competitive advantage. This paper is an initial attempt at research in the area.

Practical implications: This study presents an opportunity for purchasing managers to understand challenges more comprehensively in order to add value within the eco-innovation process. The results highlight recommendations for how best to undertake eco-innovation in upstream supply chains.

Research limitations/implications: Given the nascent state of eco-innovation practice and accessibility to primary data about ongoing efforts, this research could not consider all possible drivers.

Introduction

Since the presentation of Brundtland's report to the United Nations (UN) General Assembly in 1987, a collective awareness of the issues of sustainable development has gradually grown in society. At the Assembly, the concept of "sustainable development" was defined, for the first time, as "development that meets the needs of the present without compromising the ability of future generations to meet theirs" [START_REF] Brundtland | Presentation of the Report of the World Commission on Environment and Development to the Commission of the European Communities, the EC and EFTA Countries[END_REF]. Recently, Greta Thunberg's impassioned speech at the UN Climate Action Summit in September 2019 seems to have had an important echo, especially with young people, in the awareness of the need to escape this planetary cataclysm [START_REF] Gajanan | You have stolen my dreams and my childhood': Greta Thunberg gives powerful speech at UN Climat Summit[END_REF]. Change is the responsibility of everyone: consumers, governments but also businesses. A growing number of firms recognize environmental awareness as a business imperative. Although environmental initiatives are perceived as restrictive and costly, they have increasingly become a source of competitive parity [START_REF] Hollos | Does sustainable supplier co-operation affect performance? Examining implications for the triple bottom line[END_REF].

The managerial version of sustainable development has its source in [START_REF] Bowen | Social Responsibilities of the Businessman[END_REF]. The notion of social responsibility is gradually establishing itself within companies, in particular through regulatory frameworks, echoing the growing involvement of civil society in ecological issues. In reasoned resource management, companies must then be part of a sustainable approach to be viable in the long term [START_REF] Fel | Maturité des démarches RSE et achats durables[END_REF]. Factors such as respect for the environment, social conditions and control of the entire production chain are becoming increasingly important for firms [START_REF] Lu | Exploring sustainable supply chain management: a social network perspective[END_REF] and generally involve a change in modes of production, supply, product design and innovation [START_REF] Venkatesh | Drivers of sub-supplier social sustainability compliance: an emerging economy perspective[END_REF].

The recent concept of eco-innovation has evolved within the literature. Back in the 90s, ecoinnovation relates to products and processes which 'significantly decrease environmental impact' [START_REF] Fussler | Eco-Innovation: A Breakthrough Discipline for Innovation and Sustainability[END_REF]. Little by little, the definition encompasses more aspects, such as the innovation in technologies [START_REF] Chen | The influence of green innovation performance on corporate advantage in Taiwan[END_REF], or resources use, including energy [START_REF] Kemp | Final Report MEI Project about Measuring Eco-Innovation[END_REF]. In the meanwhile, the description of the environmental impact is also sharpened, including "reduction of environmental risk, pollution and other negative impacts" [START_REF] Arundel | Measuring eco-innovation[END_REF]. Through its evolution, the notion of eco-innovation is clearly related to the UN Goal n°12 "ensure sustainable consumption and production pattern" (United Nations, 2020, p.48). The UN goal n°12 highlights the actual unsustainable use of natural resources, while emphasizes the need of a sustainable economic growth, from government national policy initiatives to implantation of sustainability indicators by companies.

Many determinants can influence the propensity of firms to adopt eco-innovation [START_REF] Horbach | Determinants of eco-innovations by type of environmental impact-The role of regulatory push/pull, technology push and market pull[END_REF]. The national context [START_REF] Jaffe | Environmental policy and technological change[END_REF], legislation [START_REF] Costantini | Environmental regulation and the export dynamics of energy technologies[END_REF] and regulatory instruments can favour the engagement of market actors in eco-innovation activity [START_REF] Jaffe | Environmental policy and technological change[END_REF]. In their empirical results, [START_REF] Van Kemenade | Policy stringency and (eco)-innovation performance: A cross country analysis[END_REF] highlight that the firm size, environmental R&D oriented, cost reduction or commitment to environmental certifications are determining factors of eco-innovation performance.

Purchasing and supply activities are both recognized for their strategic importance in achieving a firm's long-term performance and in addressing sustainability issues [START_REF] Touboulic | Theories in sustainable supply chain management: a structured literature review[END_REF]. The impetus for innovation can lie in value chain members, such as customers and suppliers [START_REF] Hippel | The source of innovation[END_REF][START_REF] Pavitt | Sectoral patterns of technical change: towards a taxonomy and a theory[END_REF]. As purchasing is concerned with the acquisition of materials, components or services, it might be in prime position to foster innovation among the various value chain members [START_REF] Castaldi | Strategic purchasing and innovation: a relational view[END_REF]. For example, [START_REF] Melander | Collaboration beyond the supply network for green innovation: insight from 11 cases[END_REF] show that companies share their knowledge of these issues and ideas for eco-innovation across industries through collaborations with their suppliers and clients. These collaborations between actors improve environmental sustainability.

In their literature review on eco-innovation, Díaz-Garcia et al. (2015) underline important opportunities for research, such as investigations into firms' internal factors (e.g., capabilities and resources). There is also a lack of research concerning the involvement of employees in the development of eco-innovations [START_REF] Buhl | The more, the merrier: why and how employee-driven eco-innovation enhances environmental and competitive advantage[END_REF].

From this perspective, we study the extent to which the purchasing agent contributes to ecoinnovation within firms. We first establish and discuss our theoretical framework through the lenses of the resource-based view (RBV) and stakeholder theory and define the key concepts.

Next, we opted for a qualitative and exploratory study. We analyse in depth-interviews conducted with ten highly knowledgeable respondents from multisectoral organisations, associated with secondary data as supplemental. Within the overall supply chain, the focus of this paper is on the upstream and on the purchasing managers within companies. [START_REF] Penrose | The Theory of the Growth of the Firm[END_REF] identifies a firm as an organized network of individual and collective activities and a set of productive resources. These resources can be either elastic or inelastic in nature. Thus, in the approach taken by Penrose, human resources, characterized by the employees of the firm, are considered to be elastic because this productive resource can act beyond its functions and thus generate growth for the benefit of the firm. [START_REF] Wernerfelt | A resource-based view of the firm[END_REF] values the contribution of resources in a strategic analysis of the firm by placing them at the same level as the firm's products. These resources can be internal or external and participate in the creation of value. Strategic resources are a source of sustainable competitive advantage when they are valuable, scarce, difficult to imitate, nonsubstitutable and non-transferable [START_REF] Barney | Firm resources and sustained competitive advantage[END_REF]. This characterization helps organisations to identify which resources to prioritize when making strategic choices. These resources are often tacit and not easily accessible or negotiable on the market because they are specific to an organisation and are developed and controlled internally. In order to simplify the characterization of resources, [START_REF] Barney | Firm resources and sustained competitive advantage[END_REF] classifies them into three categories: physical capital resources, human capital resources, and organisational capital resources. Resources can be tangible or intangible, the latter covering capabilities, skills and knowledge.

Theoretical approach

Resource-based view

According to [START_REF] Bhupendra | Strategy to derive benefits of radical cleaner production, products and technologies: a study of Indian firms[END_REF], for example, resources such as cleaner technology implementation can facilitate eco-friendly product production.

RBV theory is often mobilized in the supply chain management (SCM) field [START_REF] Fryman | Assessing the state of procurement knowledge production: implications for the federal government[END_REF]. Diverse SCM-related activities, supply management practices and environmental management practices are considered important resources for improving operational performance [START_REF] Gavronski | A resource-based view of green supply management[END_REF][START_REF] Narasimhan | The effects of integrated supply management practices and environmental management practices on relative competitive quality advantage[END_REF]. It is important to manage these resources in order to maintain them and acquire new ones. Consequently, purchasing departments, which manage external resources, have a key role to play and must develop a supplier-oriented strategy [START_REF] Arnold | New dimensions of outsourcing: a combination of transaction cost economics and the core competencies concept[END_REF]. Recently, [START_REF] Mardani | Evaluation of green and sustainable supply chain management using structural equation modelling: a systematic review of the state of the art literature and recommendations for future research[END_REF] suggested in their literature review that the RBV had the first rank among the theories that have been used in the last decades in the assessment of green and sustainable SCM. The RBV lens has also been the most prevalent theoretical framework of study in the fields of purchasing and supply management [START_REF] Wynstra | Purchasing and supply management as a multidisciplinary research field: unity in diversity?[END_REF], purchasing social responsibility [START_REF] Carter | Purchasing social responsibility and firm performance -the key mediating roles of organizational learning and supplier performance[END_REF] and the involvement of purchasing in innovation [START_REF] Luzzini | The path of innovation: purchasing and supplier involvement into new product development[END_REF].

Stakeholder theory

Stakeholder theory states that a firm's environment is made up of stakeholders, who can influence or be influenced by the firm's activities [START_REF] Freeman | Strategic Management: A Stakeholder Approach[END_REF]. In their review of the literature, [START_REF] Lozano | A review of 'theories of the firm' and their contributions to corporate sustainability[END_REF] consider it interesting to mobilize stakeholder theory to explain the relationships that develop between a firm and its stakeholders. Primary (e.g., employees and managers, customers, suppliers and other business partners), secondary (e.g., social pressure groups, the media, academia and competitors) and regulatory stakeholders contribute to a firm's environmental commitment. Primary stakeholders are essential to the survival of firms and comprise suppliers, customers, employees and shareholders [START_REF] Clarkson | A stakeholder framework for analyzing and evaluating corporate social performance[END_REF].

Stakeholder theory is an appropriate lens through which to study SCM [START_REF] Gligor | A look into the past and future: theories within supply chain management, marketing and management[END_REF] and sustainable SCM [START_REF] Touboulic | Theories in sustainable supply chain management: a structured literature review[END_REF]. Indeed, managers should make decisions by taking the interests of all supply chain stakeholders into account [START_REF] Silvestre | A hard nut to crack! Implementing supply chain sustainability in an emerging economy[END_REF]. Taking account of such concerns helps to overcome uncertainties and builds trust and legitimacy in a sustainable supply chain. Some streams of research regarding stakeholder theory related to the natural environment have been underlined by [START_REF] Céspedes-Lorente | Stakeholders' environmental influence. An empirical analysis in the Spanish hotel industry[END_REF], such as the role of external stakeholders in assessing environmental performance and corporate environmental risks, the influence of stakeholders on the environmental strategy of firms, and the development of environmental cooperation between a firm and its various stakeholders. Cooperation with stakeholders seems to be more prominent in eco-innovative firms [START_REF] Silva Rabêlo | Drivers of multidimensional eco-innovation: empirical evidence from the Brazilian industry[END_REF]. However, less is known about the detailed profiles of stakeholders and few researchers have gathered empirical data on the approaches taken during eco-innovation [START_REF] Silvestre | A hard nut to crack! Implementing supply chain sustainability in an emerging economy[END_REF].

Therefore, we chose to mobilize both the RBV and stakeholder theory, the complementarity of which will make it possible to highlight the influence exerted by the purchasing agent's activities in the development of eco-innovation. [START_REF] Kurnia | Sustainable supply chain management capability maturity: framework development and initial evaluation[END_REF] define sustainable supply chain capability as "an organisation's capacity to deploy its resources exercised through organisational processes involved in sustainable practices" (p. 6). To implement sustainable supply chain practices successfully, companies must collaborate with suppliers and customers. Suppliers play an essential role in purchasing management and help achieve the firm's environmental objective [START_REF] Preuss | Contribution of purchasing and supply management to ecological innovation[END_REF][START_REF] Tseng | A literature review on green supply chain management: trends and future challenges[END_REF]. [START_REF] Johnsen | Purchasing and Supply Chain Management: A Sustainability Perspective[END_REF] consider that sustainability should be integrated into all procurement processes. Managers must be prepared to implement mechanisms at the corporate level to evaluate and improve the environmental performance of their suppliers.

Development of sustainable purchasing

As a growing research topic, sustainable purchasing is increasingly on the agenda of practitioners seeking to demonstrate the value of implementing these practices [START_REF] Walker | Sustainable procurement: past, present and future[END_REF]. According to [START_REF] Maignan | Managing socially-responsible buying: how to integrate non-economic criteria into the purchasing process[END_REF], sustainable purchasing practices consist of "defining socially responsible objectives for the traditional purchasing function, designating members within the organisation who are responsible for these purchases, educating suppliers, managing suppliers, controlling suppliers, sanctioning suppliers, communicating achievements to stakeholders, collecting feedback from stakeholders" (pp. 643-644). More recently, other authors have defined sustainability practices in purchasing departments as those that help companies achieve their goals by taking into account environmental aspects and social values, in addition to economic considerations [START_REF] Giunipero | Purchasing and supply management sustainability: drivers and barriers[END_REF]. According to [START_REF] Appolloni | Green Procurement in the private sector: a state of the art review between 1996 and 2013[END_REF], 'green purchases' are motivated by environmental and financial performance in relation to pressures from competitors, from legislation and from society [START_REF] Fan | Reading on and between the lines: risk identification in collaborative and adversarial buyer-supplier relationships[END_REF]. These authors present the integration of environmental aspects into the purchasing decision-making process, as well as stressing the importance of the influence of suppliers in the eco-innovation process. Based on their review of the literature, [START_REF] Appolloni | Green Procurement in the private sector: a state of the art review between 1996 and 2013[END_REF] developed a model that includes factors and obstacles (internal and external) related to green procurement. They underline the importance of internal buy-in, top management support and ways of working with suppliers, for example, but also customers and regulatory and environmental orientations.

In order to take all the aspects above into account, we here use the definition from [START_REF] Lindgreen | Sustainable procurement in the United Kingdom public sector[END_REF], which seems the most complete as it includes environmental, ethical and green issues: "Sustainable procurement is procurement that is consistent with the principles of sustainable development, such as ensuring a strong, healthy and just society, living within environmental limits, and promoting good governance" (p. 129).

The levers for implementing sustainable and green purchasing practices are more proactive than reactive [START_REF] Igarashi | What is required for greener supplier selection? A literature review and conceptual model development[END_REF]. Collaboration with suppliers seems crucial within a sustainable supply chain. [START_REF] Yen | Buyer-supplier collaboration in green practices: the driving effects from stakeholders[END_REF] demonstrates that if the senior management of a firm shows commitment, the purchasing department will be encouraged and valued in its activities of environmentally responsible collaboration with its suppliers.

Most of the literature on sustainable purchasing and supply management has focused on the economic issues related to recycling [START_REF] Arora | Strategic sustainable purchasing, environmental collaboration, and organizational sustainability performance: the moderating role of supply base size[END_REF]. Research on broader managerial concerns, such as the economic, environmental and social impact of purchasing activities, needs to be developed (Lopes de Sousa [START_REF] Jabbour | The soft side of environmentallysustainable organizations[END_REF][START_REF] Montabon | Making sustainability sustainable[END_REF].

Involvement of purchasing within innovation processes

When looking to innovate, organisations involve many functions that can interact with suppliers. As the means of managing external resources, the purchasing department plays an important role in facilitating supplier integration [START_REF] Lakemond | Coordinating supplier involvement in product development projects: a differentiated coordination typology[END_REF]. According to [START_REF] Castaldi | Strategic purchasing and innovation: a relational view[END_REF], the purchasing function is truly strategic during innovation when, on the one hand, relations with suppliers are considered strategic in the organisation and, on the other, the organisation recognizes suppliers as potential sources of innovation. It is essential in this context that purchasing is integrated into the strategic activities of the firm and develops effective collaborations with other functions [START_REF] Castaldi | Strategic purchasing and innovation: a relational view[END_REF][START_REF] Preuss | Contribution of purchasing and supply management to ecological innovation[END_REF][START_REF] Viale | Intra-functional coordination: the case of purchasing during innovation in the agri-food sector[END_REF].

The involvement of the purchasing makes it possible for it to contribute to the success of an innovation and a few authors have sought to understand the explanatory factors that promote this participation (e.g., [START_REF] Luzzini | The path of innovation: purchasing and supplier involvement into new product development[END_REF]. [START_REF] Castaldi | Strategic purchasing and innovation: a relational view[END_REF] define the key role of three variables: the quality of the purchasing function, supplier involvement and the integration of the purchasing function. In their study on the role of the upstream involvement of the purchasing function, [START_REF] Luzzini | The path of innovation: purchasing and supplier involvement into new product development[END_REF] detail the factors favouring involvement in the innovation process, such as the strategic place of purchasing in the organisation, the organisational structure of the purchasing department, the technical skills of the purchasing teams and the input from purchasing agents. Numerous authors agree that these factors allow the involvement of the purchasing function and the strategic recognition of the function internally [START_REF] Castaldi | Strategic purchasing and innovation: a relational view[END_REF][START_REF] Viale | Intra-functional coordination: the case of purchasing during innovation in the agri-food sector[END_REF].

Eco-innovation and the involvement of purchasing

It is through eco-innovation that firms can deal with challenges related to the environment. [START_REF] Kemp | Final Report MEI Project about Measuring Eco-Innovation[END_REF] proposed the following definition of eco-innovation used by the European Union (EU): "the production, assimilation or exploitation of a product, production process, service or management or business method that is novel to the organisation (developing or adopting it) and which results, throughout its life cycle, in a reduction of environmental risk, pollution and other negative impacts of resources use (including energy use) compared to relevant alternatives" (p. 7). Table II presents a chronological list of some of the definitions of eco-innovation given by other authors.

Table II. Few definitions of eco-innovation

References Definition of eco-innovation (EI) [START_REF] Fussler | Eco-Innovation: A Breakthrough Discipline for Innovation and Sustainability[END_REF] "New products and processes which provide customer and business value but significantly decrease environmental impacts" (cited from Bartlett and Trifilova, 2009, p.911).

Arundel and Kemp (2009)

"For the European Commission, eco-innovation is defined as the production, assimilation or exploitation of a product, production process, service or management or business method that is novel to the organisation (developing or adopting it) and which results, throughout its life cycle, in a reduction of environmental risk, pollution and other negative impacts of resources use (including energy use) compared to relevant alternatives" (p.5).

Eco-innovations have a positive influence on firm performance, such as better perceived quality, brand awareness and trust, as well as a firm's reputation [START_REF] Weng | Effects of green innovation on environmental and corporate performance: a stakeholder perspective[END_REF].

Proactive eco-innovation activities can correspond to a competitive advantage for a firm [START_REF] Buhl | The more, the merrier: why and how employee-driven eco-innovation enhances environmental and competitive advantage[END_REF]. [START_REF] Giunipero | Purchasing and supply management sustainability: drivers and barriers[END_REF] also highlight the importance of vision, anticipation and leadership support in this context. This is in line with the model developed by [START_REF] Appolloni | Green Procurement in the private sector: a state of the art review between 1996 and 2013[END_REF], which adds the importance of alignment with the corporate strategy. The commitment of organisations to eco-innovation enables the development of superior environmental performance, which has a positive impact on customer satisfaction and helps attract additional customers [START_REF] Chen | The driver of green innovation and green imagegreen core competence[END_REF]). In addition, [START_REF] Renwick | Green human resource management: a review and research agenda[END_REF] show that eco-innovation can enhance the attractiveness of a firm as an employer and increase the productivity and engagement of its employees.

Eco-innovation practices are pursued within the supply chain of firms and involve all the supply chain actors. Thus, inter-organisational relationships play a major role in ecoinnovation activity. All actors then activate managerial and operational processes, information systems and technologies to optimize the entire supply chain through several innovative practices, such as supply chain agreements, reverse logistics, after-sales service and transportation [START_REF] Ageron | Innovative supply chain practices: the state of French companies[END_REF]. Even if these innovation practices are not always characterized as eco-innovation [START_REF] Ageron | Innovative supply chain practices: the state of French companies[END_REF], they are aimed at reducing the negative externalities resulting from supply chain activity [START_REF] Ageron | Sustainable supply chain management: An empirical study[END_REF][START_REF] Ashby | Making connections: a review of supply chain management and sustainability literature[END_REF].

Eco-innovation in the supply chain is essential to ensure the performance of all the actors involved. [START_REF] Cicconi | Eco-design and eco-materials: an interactive and collaborative[END_REF] considers the importance of collaboration between a purchasing company and its suppliers throughout the engineering activities and the value chain for the success of eco-innovation.

Among eco-innovation practices within the supply chain, several are carried out upstream, involving suppliers and thus purchasing managers. Some suppliers propose eco-innovations to the purchasing team, and some certifications (e.g., Standard ISO14001) could be of great interest for procurement in order to bring value during eco-innovation [START_REF] Preuss | Contribution of purchasing and supply management to ecological innovation[END_REF].

The literature regarding eco-innovation remains in its infancy and numerous researchers consider that the subject lacks research with empirical data [START_REF] Klewitz | Sustainability-oriented innovation of SMEs: a systematic review[END_REF]. It has recently been argued that "the studies related to eco-innovation are still preliminary and that the subject lacks specific research with empirical data from survey and in-depth case studies" (Maçaneiro et al., 2013, p. 179). For [START_REF] Buhl | The more, the merrier: why and how employee-driven eco-innovation enhances environmental and competitive advantage[END_REF], there is a lack of research concerning the involvement of employees in the development of eco-innovations. In addition, according to some authors, the majority of studies examining the development of ecoinnovations in the automotive industry have focused on the R&D efforts of manufacturers, with little consideration of the eco-innovation capabilities of suppliers (e.g., [START_REF] Borgstedt | Paving the road to electric vehicles -a patent analysis of the automotive supply industry[END_REF].

As referred to earlier, purchasing and supply activities are acknowledged for their strategic importance in achieving long-term performance and addressing sustainability issues [START_REF] Touboulic | Theories in sustainable supply chain management: a structured literature review[END_REF]. The locus of innovation can be found in value chain members, such as customers and suppliers [START_REF] Hippel | The source of innovation[END_REF][START_REF] Pavitt | Sectoral patterns of technical change: towards a taxonomy and a theory[END_REF]. Purchasing is concerned with the acquisition of materials, components or services, so could be in prime position to foster innovation among the various value chain members [START_REF] Castaldi | Strategic purchasing and innovation: a relational view[END_REF]. [START_REF] Preuss | Contribution of purchasing and supply management to ecological innovation[END_REF] shows that purchasing managers can play a role in managing eco-innovations in supply chains, such as: addressing arm's-length requests of suppliers to innovate, facilitating collaboration among supply chain members, lobbying for internal acceptance of supplier innovation and defining supplier evaluation criteria and component specifications.

Most of the eco-innovations in Preuss' sample (2007) are focused on green innovations, such as packaging and waste recycling, in response to specific legislation. Other gaps have been highlighted in previous studies, such as the need to explore more deeply how the human side of organisations can support green production processes [START_REF] Jabbour | The soft side of environmentallysustainable organizations[END_REF].

In a context of ecological transition, this study aims to fill the existing gaps and explore what fosters the participation of the purchasing agent and identify the drivers of and difficulties encountered during the development of eco-innovation within firms.

Research methodology

As the literature regarding eco-innovation remains scarce, we opted for a qualitative and exploratory study [START_REF] Tukamuhabwa | Supply chain resilience in a developing country context: a case study on the interconnectedness of threats, strategies and outcomes[END_REF] to answer the following research question:

What are the constituent resources needed to foster the involvement of purchasing in ecoinnovation in order to achieve a sustainable competitive advantage? The aim of a qualitative and exploratory approach is to better understand and contextualize a phenomenon [START_REF] Papalexi | Key sources of operational inefficiency in the pharmaceutical supply chain[END_REF]. A call for more qualitative research has been made by several authors (e.g., [START_REF] Mangan | Combining quantitative and qualitative methodologies in logistics research[END_REF][START_REF] Näslund | Logistics needs qualitative research -especially action research[END_REF], as well as for more exploratory-based knowledge methodologies [START_REF] Towers | The impact of phenomenological methodology development in supply chain management research[END_REF], in order not to reduce SCM studies to a single research paradigm [START_REF] Wagner | Editorial: 20 years of Supply Chain Management: An International Journal[END_REF]. First, the context of eco-innovation is specified, based in particular on a study by the National Institute of Statistics and Economic Studies (INSEE).

Then semi-structured in-depth interviews were done to understand why a purchasing agent carries out eco-innovation practices.

Supplemental data source to analyse eco-innovation in firms

As Ellram et al. (2016, p.250) mentioned, secondary data is growing in importance in purchasing and supply management research and can be an interesting supplemental data source. Secondary datasets often use well-established measures that add credibility when combined with the results of another study (Ellram et al., 2016, p.251). The use of secondary data allows researchers in purchasing in supply management [START_REF] Ellram | The use of secondary data in purchasing and supply management (P/SM) research[END_REF] Employing the definition proposed by [START_REF] Arundel | Measuring eco-innovation[END_REF], the INSEE study poses companies questions about their eco-innovation activities. Thus, defined for the respondents, the concept of eco-innovation is then addressed in the questionnaire in its operational form through the following question: "Are you developing eco-innovations, that is, goods or services that are more respectful of the environment?" (Answer: Yes/No). The data collected were analysed using descriptive statistics.

Additional data extracted from INSEE allowed us to think that elements which apparently really count in eco-innovation activity are size and sectors. First, we notice that, on average, one quarter of the companies with a workforce of fewer than 250 employees reported ecoinnovation activity. We also note that eco-innovation activity is developed in greater proportions in mid-size companies (250 employees and more; 35.9%) and large companies (500 employees and more; 46.3%). This can be explained mainly by the perception of small and medium-sized enterprises (SMEs) regarding the concept and definition of eco-innovation (see Table III). There is also a size effect, which is linked to organisational structure. Both large and medium-sized companies are more likely to have an operational and structured purchasing department compared with smaller companies. Second, concerning sector analysis, energy (29.8%) occupies the top position and real-estate and administrative services hold joint second place (28.4%) (see Table IV). The two sectors bringing up the rear are professional, scientific and technical activities (13.3%) and information and communication (9.3%). Companies within the sectors of activity linked to the production and transformation of natural resources are more involved in the activity of eco-innovation. The results of this study indicate that the position of a firm within its supply chain did not affect the respondents' answers (see Table IV). Thus, companies are visibly progressively engaging in eco-innovation. However, a question remains as to the possibility of being able to identify which are the major actors of ecoinnovation activity within a supply chain. The purchasing function plays a major role in optimizing the procurement process. We can, therefore, reasonably put forward the idea that the purchasing agent represents a key source of eco-innovation activity.

In-depth interviews with purchasing agents

In order to highlight the mechanisms underlying the activity of eco-innovation revealed, we studied the perceptions, accounts and practices of purchasing agents.

A semi-structured interview guide allows researchers to enhance the reliability of results [START_REF] Yin | Designing case studies[END_REF] and to gather information about the experiences, views, beliefs or motivations of individuals [START_REF] Papalexi | Key sources of operational inefficiency in the pharmaceutical supply chain[END_REF]. We drew up an interview guide comprising fourteen questions, divided into five parts: introduction, context, process, contributions of actors, and key factors of success and difficulties. Our goal was to ascertain the current roles and challenges related to eco-innovation within a purchasing department.

In order to conduct the in-depth interviews, we targeted actors in purchasing departments who have a proven track record and have participated in eco-innovation projects. One of the critical factors was the selection of highly qualified respondents. We looked for respondents with at least three years of experience in purchasing and with experience in eco-innovation projects. We contacted several potential respondents by email and asked them to recommend other profiles that matched our search criteria. We were therefore able to select purchasing agents who are specialists in their field of expertise, come from different sectors of activity, and belong to firms of various sizes, all located in Europe. All these criteria contribute to the robustness of our work. Of a total of 65 potential responders, ten (whose profiles corresponded to our objectives) agreed to take part in our study. We then explained the objectives of the research to the ten respondents.

Note: FMCG = fast-moving consumer goods

An iterative process begins with theoretical questioning and evolves as it is confronted with empirical data [START_REF] Yin | Designing case studies[END_REF]. We used a multi-thematic coding method [START_REF] Saldaña | Coding and analysis strategies[END_REF] to analyse transcripts of the respondents' interviews. We first systematically cut and coded all the material into units of meaning. We then began the dual task of identifying similarities and differences. We also tried to highlight recurrences or repetitions. The coding made it possible to identify and retain eight themes: (1) strategy of the organisation in relation to innovation;

(2) organisation of innovation (teams involved, etc.); (3) internal integration of the purchasing function; (4) integration of suppliers; (5) nature of the implications and involvement of the purchasing function; (6) drivers or prerequisites; (7) nature of the suppliers' relationship; and (8) challenges and difficulties encountered.

Empirical findings

In order to answer our question concerning the purchasing function, we studied whether the purchasing agent constitutes an unavoidable strategic key actor in eco-innovation activity.

Based on the discourse of professionals working in purchasing, we shed light on why and how purchasing influences eco-innovation. We will then be able to understand in what way(s) the purchasing function can influence the emergence of eco-innovation in companies and throughout the value chain. Our in-depth interviews allow us to present the set of intraorganisational and inter-organisational factors that are considered as key in this context according to the majority of respondents, and also the most frequently cited elements, such as drivers and barriers.

Intra-organisational factors in fostering the involvement of purchasing in ecoinnovation

All the participants affirm that the support of the general management strategy in a sustainable and environmentally oriented approach is a favourable condition, as well as the involvement of the actors in the development of eco-innovation.

We define ourselves as a company that uses its business practices to drive long-term environmental, social, governance and financial value creation. The CSR approach is based on the Group's guidelines and is applied at the territory and entity levels in an ethical and responsible manner. (Resp 6)

This strategy is not simply a display, but a reality experienced on a day-to-day basis by all the company's players:

We believe that sustainable development should not be an idea, but an everyday reality. Therefore, we have developed a way of being and producing responsibly at all levels, from processes to materials, from the environment to health, to our responsibility as citizens and towards our employees. A state of mind recognized today by the main labels and certifications. (Resp 4) Some of the respondents' companies are embarking on a B Corp audit (B Corporation certification is awarded by B Lab, a non-profit organisation, on the basis of a for-profit organisation's social and environmental performance) and others were already certified.

We are expecting the collective of its water brands to achieve B Corp certification worldwide by 2022. In this way, we join the collective of companies that act to make a positive contribution to society. For example, we are aiming to reach 50% recycled PET use worldwide and 100% across Europe in 2025. (Resp 5)

The audits sometimes reveal a lack of analysis and data on carbon impact and water and energy consumption. Decarbonizing supply chains is, therefore, a key challenge:

Production requires energy and also steam. Steam is used to melt the chocolate. We have decided to reach "Zero carbon emissions by 2040" and chosen to review the operation of our factories. The largest factory in France was the first to benefit from "green steam". A 1,300-metre heating network connects the factory to the energy recovery unit for household waste in the town near the factory. The results were very positive: this new network now satisfies 90% of our needs. At the same time, it leads to a 60% reduction in greenhouse gas emissions. This is the result of a partnership with key stakeholders. (Resp 9)

According to the majority of respondents, eco-innovation (or at least innovation and sustainable development taking place at the same time) should also be part of the strategic objectives of the purchasing department:

For me it is essential, people are open and curious. Any kind of initiative is encouraged and even valued within my department, and even more so in strategic innovation projects related to sustainable development. (Resp 6)

I am working day to day with the Global Circular packaging director in order to screen all our new packaging through a design tool dedicated to recyclability to anticipate their end-of-life. We are also working on design and materials, for example by simplifying flexible packaging, such as water bottles, with the use of a single type of plastic, to facilitate their end-of-life and recyclability. (Resp 5)

Inter-organisational factors in fostering the involvement of purchasing in ecoinnovation

The importance of developing a high-quality relationship with suppliers appears to be an essential solution to the development of eco-innovation. Indeed, before a supplier can be integrated into innovation projects, the relationship must be based on mutual trust and fair conditions. These terms are above all developed with strategic suppliers, who are best able to know the company and bring their expertise to it. For example:

In my opinion, thanks to the reflections on these subjects, we are engaging in a partnership with suppliers, based on shared values on sustainable development issues. We enter into a real dynamic of value creation with the supplier. (Resp 5)

We also have to make suppliers want to come and work with us, and when we make them want to and when we show that we have a potential in line with real values and that behind this potential lies a virtuous circle. Seeing that the commitment made is respected, the following year the supplier has confidence and that's how it is built and we move forward with the supplier. (Resp 1)

It is, therefore, essential to select reliable suppliers carefully who will be able to provide support and solutions to the firm over the long term. The purchasing agent will then be able to support innovation processes with the supplier. One respondent recounted an example in which a supplier proactively proposed a new, greener solution. This solution consisted of a reusable odour filter to replace the disposable filters used previously. The innovation suggested by the supplier led the company to codevelop the new filters with him in order to integrate this solution within the group. As a result of this eco-innovation, the partners have achieved a significant reduction in waste, as well as a decrease in their costs, and the product's lifespan has been increased. The purchasing department encourages its suppliers to be proactive:

I

The individual purchasing agent's willingness and sensitivity in focusing on the end customer

We observed in many of the interviews that, through their detailed understanding of the needs of the end customers, the purchasing agents act upstream and can anticipate future ecoinnovations:

We are integrated at a very early stage of the innovation process, known as sustainable innovations. I consider that the further away the buyers are from reality, from our end customer, the less innovation there will be adapted to the customer's real needs… Never forget, the client is our boss! (Resp 9)

The purchasing agent is sensitive to the expectations of the end customer, particularly with regard to sustainability. By focusing on these aspects, the agent can proactively propose ideas to suppliers and internally through lobbying:

Suppliers and production management are not aware of the level of demand from the end consumer. We explain what is important for us and therefore for our end customer! (Resp 6)

This can be linked to curiosity and the capacity to have a holistic view that influences the individual's innovation behaviour.

The intrinsic and societal values of the purchasing agent

During the interviews we conducted, we observed that eco-innovation initiatives are mainly and surprisingly the result of personal initiative on the part of the purchasing agent. Through personal convictions and values, the purchasing agent will seek and propose a more ecological and innovative approach to internal customers when they submit what they need, favouring a co-development or evolutionary development of the specifications to bring the agent's expertise and that of the suppliers in terms of eco-innovation:

I'm involved as a citizen, also in professional buyers' networks to keep an eye on the market every week, to follow the ecological innovations that could fuel my ideas and the projects I believe in. (Resp 2)

Purchasing agents will be quicker to use their resources, time, in this case, to achieve goals that correspond to their values and which they can achieve individually. Through their convictions, purchasing agents thus build a unique body of knowledge that is their own (through the active capture of knowledge regarding their interests), step by step becoming an expert in eco-innovation in relation to their particular commodity:

A buyer in my team proposed to recover fruit water, low in calories and mix it with the fruit juice. The objective is to reduce sugar and calories: to obtain a product 100% from the same fruit. This is a radical innovation for the market. (Resp 7)

This point echoes the importance of the personal values: a purchasing agent convinced of the importance of eco-innovation will pose less resistance and will even suggest ideas on some eco-innovation projects.

What barriers and obstacles are encountered?

Resistance to change on the part of the purchasing agent was widely cited by the respondents.

It appears to be one of the main limits to the integration of purchasing, as eco-innovation objectives are sometimes considered an additional constraint and not a strong added value.

For example:

We realize that people do not like change. Indeed, to transform processes, to innovate while considering environmental or social constraints, purchasing should necessarily be a source of change and propose to work differently with suppliers and internal clients. You can't work in your own corner, it's much too dangerous! So, you need to be convinced as well as the project's team. (Resp 9)

The lack of harmonized indicators on sustainable procurement was found to be another of the most frequently cited barriers. One of the main obstacles to the development of eco-innovation is that the purchasing agent is still often seen as simply a 'cost-killer'. For many respondents, the objectives of economic profitability and financial performance are at the heart of their concerns. The senior management therefore sets cost reduction objectives that the purchasing department must achieve. In order to measure the purchasing department's performance on these objectives, one of the only indicators used is directly related to the savings achieved. Thus, these objectives and indicators lock purchasing agents into a purely cost-reduction role. This does not encourage them to take further action, as most of them are not evaluated on other criteria. As the long-term savings do not figure into any envisioned business plans or budgetary cycles, it is difficult to justify spending more money than allotted for the procurement of sustainable solutions or products.

At last, our respondents also consider that consumer adoption of eco-innovation is key for the business, and innovation success. If it is not the case then, the eco-innovation can't be kept on the marketplace in a sustainable manner.

The cost and the willingness (or not) of the end customer to accept and buy in this innovation. The market has to be ready! (Resp 10)

Discussion

In this study, we aimed to investigate the involvement of purchasing agents for the purpose of eco-innovation, a topic deemed necessary [START_REF] Preuss | Contribution of purchasing and supply management to ecological innovation[END_REF] but not often studied empirically in the literature [START_REF] Klewitz | Sustainability-oriented innovation of SMEs: a systematic review[END_REF][START_REF] Maçaneiro | Drivers of the adoption of ecoinnovations in the pulp, paper, and paper products industry in Brazil[END_REF]. We considered firms' internal factors (e.g., capabilities and resources) and the external factors that foster the involvement of purchasing in the development of eco-innovations.

Intra-organisational factors in fostering the involvement of purchasing in ecoinnovation

Similar to previous studies, our results show that firms develop a general management strategy as part of a sustainable and environmentally oriented approach [START_REF] Appolloni | Green Procurement in the private sector: a state of the art review between 1996 and 2013[END_REF][START_REF] Giunipero | Purchasing and supply management sustainability: drivers and barriers[END_REF]. This strategy is not simply a display, but a reality experienced on a day-to-day basis by all the company's players. This result complements those of [START_REF] Buhl | The more, the merrier: why and how employee-driven eco-innovation enhances environmental and competitive advantage[END_REF], who stress the importance of a deliberate corporate strategy.

In line with for example [START_REF] Preuss | Contribution of purchasing and supply management to ecological innovation[END_REF], and [START_REF] Van Kemenade | Policy stringency and (eco)-innovation performance: A cross country analysis[END_REF], commitment to environmental certifications are of great interest for procurement in order to bring value during eco-innovation, and determining factors of eco-innovation performance (Resp 4, 5 and 6). Some respondents in our study stressed that innovation and sustainable development must also be part of the strategic objectives of purchasing departments (Resp 1, 2, 3, 4, 5, 6, 7, 9 and 10).

Firms give their employees the freedom to undertake innovative projects. Moreover, our results show the willingness of purchasing agents to contribute to eco-innovation. The notion of commitment to employee initiative was raised by [START_REF] Renwick | Green human resource management: a review and research agenda[END_REF]. In a complex, uncertain and rapidly changing world, purchasing agents must carefully observe, find and seize opportunities arising from meetings at trade fairs, or with suppliers, or have sufficient confidence in their own creativity to propose eco-responsible ideas. Thus, according to our respondents, the innovation process starts with 'one person', in this case, the purchasing agent, who innovates. The ability to take on the role of an individual entrepreneur is known and dear to [START_REF] Schumpeter | Methodological Individualism, Institutum Europaeum[END_REF].

Through the lens of stakeholder theory, "some of the stakeholders that are influential inside the firm include employees and mid-level managers" (Meixell and Luoma, 2015, p. 70). The purchasing agent is involved early in the innovation process and can add value [START_REF] Luzzini | The path of innovation: purchasing and supplier involvement into new product development[END_REF] and influence, as well as being able to involve the supplier early in the strategic process [START_REF] Schiele | How to distinguish innovative suppliers? Identifying innovative suppliers as new task for purchasing[END_REF].

Inter-organisational factors in fostering the involvement of purchasing in ecoinnovation

It is known that firms rely on the products and services they buy from their suppliers to improve their own market offering and to increase the overall profitability of their firm [START_REF] Ulaga | Capturing value creation in business relationships: a customer perspective[END_REF]. Organisations with proactive approaches to collaboration with supply chain actors develop more innovative solutions [START_REF] Soosay | Supply chain collaboration: capabilities for continuous innovation[END_REF]. [START_REF] Kern | Purchasing competence: a stakeholder-based framework for Chief Purchasing Officers[END_REF] consider that suppliers are the stakeholder group with the strongest impact on purchasing performance.

The importance of developing a high-quality relationship with suppliers appears to be essential to the development of eco-innovation. Within eco-innovation, our results point to the exchange of information, cooperation and the pooling of the resources of each party as being essential. In this way, the supplier will have better knowledge of the internal organisation (its processes and implicit needs) and be in a better position to help its customers. The supplier will also be able to be a force for offering suggestions and sharing practices or ideas for eco-responsible innovations. This attitude requires a strong integration of the stakeholders and a consequent commitment from them in the implementation and follow-up of a common decision system. For optimal collaboration, communication and exchanges between the two parties must, therefore, be regular and valued [START_REF] Awan | Creativity enables sustainable development: supplier engagement as a boundary condition for the positive effect on green innovation[END_REF].

It is, therefore, essential to take the time to select reliable suppliers who will be able to provide support and solutions to the company over the long term. These results are in line with the work of [START_REF] Castaldi | Strategic purchasing and innovation: a relational view[END_REF], who stress the importance of supplier involvement in the context of innovation, and of [START_REF] Cicconi | Eco-design and eco-materials: an interactive and collaborative[END_REF] in projects specifically related to ecoinnovation.

The individual purchasing agent's willingness and sensitivity in focusing on the end customer

We observed thanks to the respondents' answers, that, through a detailed understanding of the needs of end customers, purchasing agents act upstream and are able to anticipate future ecoinnovations. Purchasing agents are sensitive to and, therefore, influenced by the expectations of end customers, particularly with regard to aspects of sustainability. By focusing on these aspects, agents can proactively propose ideas to suppliers and internally through lobbying (Resp 2, 5, 7).

The intrinsic and societal values of the purchasing agent

Previous study has underlined that eco-innovation was predominantly brought about by legislation [START_REF] Preuss | Contribution of purchasing and supply management to ecological innovation[END_REF]. Although standards and regulations in terms of sustainable development are increasingly becoming more rigorous and are no longer simply recommendations, our results highlight that eco-innovation approaches are mainly the result of personal initiative on the part of the purchasing agent. Indeed, through personal convictions and values, purchasing agents will seek and propose more ecological and innovative approaches to their internal customers when they put forward a requirement, favouring the co-or evolutionary development of the specifications to bring the agents' expertise and that of their suppliers to an eco-innovation.

As individuals, purchasing agents will be quicker to use their resources to achieve goals that correspond to their values and which they can achieve individually. Personal involvement seems to be a necessary component in order to circumvent the many difficulties. By virtue of their personal values and intrinsic motivations, purchasing agents will tend to seek, detect and favour eco-innovation actions and in their initiatives that are within the scope of their area of technological expertise. Our results address social dimensions that have not previously been studied in the sustainability SCM and purchasing literature (Lopes de Sousa [START_REF] Jabbour | The soft side of environmentallysustainable organizations[END_REF]. [START_REF] Buhl | The more, the merrier: why and how employee-driven eco-innovation enhances environmental and competitive advantage[END_REF] considered that the multiple potential and innovative capacity of employees in eco-innovation processes had hardly been examined. Our results reveal a potential differentiating role of the purchasing agent in the eco-innovation process. In this sense, this result highlighted something unexpected.

If a purchasing agent is to bring an eco-innovation project to the management committee and defend it to all internal and external stakeholders, the purchasing department must develop the leadership and influence skills to persuade internal departments to accept the shift in approach and collaborate on projects in order to bring about a change in processes. This result is, to the best of our knowledge, a contribution to the literature. From the stakeholder lens, we

show the role and influence of the internal stakeholder, here purchasing agent, in the ecoinnovation activity.

Our analysis of the cases revealed some differences of opinion that can be linked to the size of the company, such as the reason for implementing eco-innovation projects. For example,

Resp 2 (a raw material purchasing manager) acknowledged that it is essentially due to the growing demand of customers and the regulatory and legal requirements that her organisation has adapted a strategy for certain categories of purchase. Thus, this organisation has a reactive adoption profile as a response to constraints or pressures from its stakeholders [START_REF] Porter | Strategy and society: the link between competitive advantage and corporate social responsibility[END_REF].

What are the barriers to resources?

Resource barriers are issues to do with capacity (e.g., resource shortages) and capability (e.g., gaps in knowledge). Purchasing agents should not simply be seen as cost-killers because a mature purchasing department is an asset to developing competitive advantages through innovation [START_REF] Luzzini | The path of innovation: purchasing and supplier involvement into new product development[END_REF]. This is all the more relevant given that environmental clauses are increasingly being imposed that mean that suppliers must be involved upstream in order to capture the innovations needed to achieve performance objectives, particularly in terms of energy efficiency. This result confirms previous research [START_REF] Lintukangas | The role of supply management innovativeness and supplier orientation in firms' sustainability performance[END_REF].

Resistance to change was cited by the respondents we surveyed. This resistance appears to be an important limit, as it means that eco-innovation objectives are considered an additional constraint and not as having strong added value. The purchasing agent's ability to support internal and external actors in change management seems to be a major asset in this context.

At last, our respondents (Resp 2, 7, 9 and 10) consider that consumer adoption of eco-innovation and their readiness for the eco-innovation is key for the business, and ecoinnovation success. This is an additional proof that the purchasing agent, thanks to his holistic view, develops his behaviour versus innovation and takes into consideration the endconsumer.

Conclusion

This study provides new insights into the constituent resources needed for successful purchasing considerations during eco-innovation in order to obtain a sustainable competitive advantage. We first and foremost show empirical evidence from our results that firms are visibly progressively engaging in eco-innovation.

Purchasing and supply activities are both recognized for their strategic importance in achieving a firm's long-term performance and in addressing sustainability issues. Limited research is available regarding what capabilities are needed for sustainable purchasing during eco-innovation. Therefore, we aimed to investigate the involvement of purchasing agents for the purpose of eco-innovation, a topic deemed important but not often studied empirically in the literature [START_REF] Klewitz | Sustainability-oriented innovation of SMEs: a systematic review[END_REF][START_REF] Maçaneiro | Drivers of the adoption of ecoinnovations in the pulp, paper, and paper products industry in Brazil[END_REF]. We can reasonably put forward the idea that the purchasing agent represents a key resource in an eco-innovation activity. Thus, we considered firms' internal factors (e.g., capabilities and resources) and the external factors that foster the involvement of purchasing in the development of ecoinnovation.

The results showed that the support of the general management strategy in a sustainable, environmentally oriented approach is also conducive to the development of eco-innovation.

Without an overall strategy, the introduction of objectives at the level of the purchasing department and potential performance indicators that bring together ecology and innovation are limited. This result complements those of [START_REF] Buhl | The more, the merrier: why and how employee-driven eco-innovation enhances environmental and competitive advantage[END_REF], who show the importance of establishing a deliberate sustainability strategy at the level of the company's management.

Finally, statements collected from some participants indicate that engagement in environmental certifications generates great opportunities for eco-innovation, which tends to confirm the results of previous studies (Kemenade and Teixeira, 2017).

Drawing on [START_REF] Silvestre | A hard nut to crack! Implementing supply chain sustainability in an emerging economy[END_REF] recent call for further research on the interaction between stakeholder theory and the sustainable SCM discourse, this study provides empirical findings on a functional level. We aim to address a gap in previous research regarding the extent to which companies consider the internal and external stakeholders in their upstream supply chains in their eco-innovation activities.

Using the stakeholder lens, we show the role and influence of some of the internal and external stakeholders in the eco-innovation activity generated and driven by purchasing agents. In addition, with regard to external stakeholders, purchasing departments are increasingly looking outwards to capture innovation. Collaboration with strategic suppliers allows the emergence of ideas and the creation of new concepts, processes or products that will help the company to differentiate itself. The purchasing department is thus encouraged to communicate to suppliers its desire to create a partnership and to adopt an open innovation model that focuses primarily on eco-innovation projects. The strong relationships built over time between business partners help to strengthen their commitment and involvement in innovative projects. Moreover, the ideas carried by suppliers often represent powerful relays for potential value creation. The proactivity shown by purchasing agents often favours the commitment of stakeholders who are prominent in innovative thinking.

Finally, the profile of purchasing agents must be in line with the firm's current issues. The adoption of systems thinking [START_REF] Bals | Purchasing and supply management (PSM) competencies: current and future requirements[END_REF] is a key capability for the purchasing agent to acquire within the eco-innovation context. Furthermore, we show that entrepreneurial capacity, purchasing agents' individual sensitivity to issues related to sustainable development, as well as their personal values, have a strong impact on the missions and choices made. By virtue of their personal values and intrinsic motivations, purchasing agents will tend to seek, detect and favour eco-innovation actions and initiatives. Furthermore, our results address social dimensions that have not previously been studied in the sustainability SCM and purchasing literature (Lopes de Sousa [START_REF] Jabbour | The soft side of environmentallysustainable organizations[END_REF]. Our study contributes to the literature and shows that there is also a need to raise awareness and possibly train the various actors in this subject.

The skills and resources held and mobilized by buyers are essential to a firm's operating activities. Nevertheless, these factors are not sufficient to explain the eco-innovation generated by the buyers' actions. Overcoming constraints on functions useful for exploration activities requires the mobilization of resources and skills held by internal stakeholders, as well as others present outside the firm's boundaries. Thus, the combination of buyers' knowhow and skills in their relations with stakeholders will contribute to the emergence of proactive sustainable behaviours that are a vector for eco-innovations on the part of their partners in the supply chain.

Limitations and research perspectives

The majority of our respondents come from organisations in which the observation of ecoinnovation was possible during our interviews. Often, those organisations are large firms that belong to international groups. Contextual factors, such as the significance of the sector of activity, represent interesting perspectives when studying eco-innovation and indicate a path for further research.

We did not include respondents from start-ups with a business model developed entirely around the issue of sustainable development and eco-innovation. We can observe this trend as a result of the flourishing number of innovative start-ups on this theme. For example, the French Too Good To Go fights against food waste across fourteen European countries, and the fully edible and biodegradable Ooho water bubble of the British Skipping Rock Labs aims at reducing the production of plastic waste. These start-ups have a very specific culture and strategy, and we can assume that eco-innovation will be part of their DNA. Studying the role and place of the purchasing department in these structures represents relevant research perspectives. At the same time, this raises the issue of Open Innovation [START_REF] Chesbrough | The New Imperative for Creating and Profiting from Technology[END_REF], defined as the collaboration between start-ups offering eco-innovation and large groups offering financial resources. Many large international groups are developing start-up incubators to capture innovation, and eco-innovation, at the source. The role and place of the Open Innovation purchasing agent with start-ups in the field of eco-innovation is, therefore, a line of thought to be considered in future research.

As our study is exploratory, we suggest extending this work in the future by mobilizing resources oriented towards environmental protection within the framework of the innovation activity in Hart's natural-resource-based view model (1995). This model would allow us to identify which strategy is implemented by purchasing agents in SCM in order to adopt ecoinnovation. The model would potentially be very helpful for managers intending to define and develop eco-innovation in SCM more simply.

Another future research direction could be to address in depth the issue of conflict within the supply chain of implementing eco-innovation solutions at potentially higher costs and the inherent push by companies on their supply chains to deliver lower costs.

There are other potential opportunities for future research. With regard to COVID-19 pandemic and uncertain business environment, digitalisation is viewed as a driver in order to obtain greater supply chain resilience [START_REF] Zouari | Does digitalising the supply chain contribute to its resilience?[END_REF]. Furthermore, numerous studies underline the need to explore the implications of technologies for sustainability in SCM [START_REF] Liu | New technologies in operations and supply chains: Implications for sustainability[END_REF][START_REF] Sarkis | Digitalization and the greening of supply chains[END_REF], together with innovation [START_REF] Bag | Big data analytics as an operational excellence approach to enhance sustainable supply chain performance[END_REF]. For example, big data, known as one of digital tools, refers to cleaner production through eco-innovation and to the potential in decreasing CO2 emissions [START_REF] Munodawafa | Big data analytics capabilities and ecoinnovation: a study of energy companies[END_REF]. Also, digitalisation can improve eco-design. As [START_REF] Gu | An integrated architecture for implementing extended producer responsibility in the context of Industry 4.0[END_REF] note, information sharing among stakeholders and data exchanges during the development and manufacturing phases can provide useful data to make products and production processes more sustainable. Digitalisation can impact working conditions in a positive or negative manner, therefore it relates to social sustainability performance [START_REF] Beltrami | Industry 4.0 and sustainability: Towards conceptualization and theory[END_REF]. Indeed, digitalisation talent capabilities result in effective employee development, which can generate new employee competencies [START_REF] Bag | Big data analytics as an operational excellence approach to enhance sustainable supply chain performance[END_REF]).

It appears that the literature focuses on the pros of these new technologies but rarely on the cons, and especially from the social perspective [START_REF] Liu | New technologies in operations and supply chains: Implications for sustainability[END_REF]. As moving forward with technological innovativeness is highly desirable [START_REF] Bag | Big data analytics as an operational excellence approach to enhance sustainable supply chain performance[END_REF], it would be essential to investigate further this in the context of eco-innovation in the upstream supply chain.

Information:

  This work has benefited from state aid managed by the French National Research Agency under the Investissements d'avenir (Investments in the Future) programme bearing the reference ANR-10-EQPX-17 (Centre d'accès sécurisés aux données, CASD / Secure Access Data Centre).

Table I .

 I Table I details those factors. Main factors in the success of the involvement of the purchasing department in the innovation process

Factors in the success of the involvement of the purchasing department during the innovation process References

	Innovation is a strategic priority of the organization	Luzzini et al. (2015)
		Viale (2019)
	Support from general management, recognition	Hillebrand and Biemans (2004)
	of the purchasing department by top management	Ellram and Carr (1994)
	Strategic position of the purchasing department	Viale (2019)
	Importance of R&D expenditure	Wynstra et al. (2000)
	Importance of the innovation project
	One of the objectives of the purchasing department	Pham (2014)
	is participation in innovation	Viale (2019)
	Efficient integration and collaboration of the	Castaldi et al. (2011)
	purchasing department with other departments	Viale (2019)
	Buyers' skills (technical expertise)	Bals et al. (2019)
		Luzzini et al. (2015)
		Pham (2014)
		Schiele (2006)

Suppliers are seen as potential sources of innovation

[START_REF] Castaldi | Strategic purchasing and innovation: a relational view[END_REF]) Monczka et al. (2015)

Vacher (

2019

)

The quality of supplier-buyer relationships (trust, cooperation, mutual interests, etc.)

Monczka et al. (2015)

  [START_REF] Chen | The influence of green innovation performance on corporate advantage in Taiwan[END_REF] "related to green products or processes, including the innovation in technologies that are involved in energy-saving, pollution-prevention, waste recycling, green product designs, or corporate environmental management" (p. 332).

	Kemp and Pearson
	(2007)

"

[EI]

results, throughout its life cycle, in a reduction of environmental risk, pollution and other negative impacts of resources use (including energy use) compared to relevant alternatives" (p. 7).

  sample of 80,445 firms from various sectors were examined. The data were gathered from a survey conducted by the National Institute of Statistics and Economic Studies (INSEE) in May 2019. The secondary data must also have contextual validity to be meaningfully used[START_REF] Ellram | The use of secondary data in purchasing and supply management (P/SM) research[END_REF]. The INSEE study was compiled from the Sirus business register and

	seeks to establish an inventory of firms engaged in sustainable development and corporate
	social responsibility (CSR) by taking account of various dimensions: environmental,
	economic and social. The 55 questions used in the INSEE study are closed-ended (yes, no,
	don't know/not concerned, or, in some cases, multiple choice). The information collected is,
	therefore, strictly quantitative and discontinuous. This INSEE study is considered as a well-
	established source of data.

to triangulate findings from principal data collection such as interviews for example. For our research, the secondary data help us determine whether eco-innovation is a reality among numerous firms. A

Table III .

 III The main factor : Eco-innovation of companies according to the numbers of employees

	Sample	80 445	23.3	76.7
	20 to 49 employees	52 488	20.2	79.8
	50 to 249 employees	22 938	26.7	73.3
	250 to 499 employees	2 878	35.9	64.1
	500 employees and more	2 141	46.3	53.7
	Size	Population	Developing eco-innovation
			Yes (%)	No (%)

Table IV .

 IV The second main factor : Eco-innovation of companies according to sector of activity

	Sector of activity	Population	Developing eco-innovation
			Yes (%)	No (%)
	Sample	80 445	23.3	76.7
	Food processing	3 176	22.5	77.5
	Extractive and manufacturing	14 757	26.4	73.6
	Energy and environment	1 052	29.8	70.2
	Construction	9 956	21.2	78.8
	Retail trade, repairs	11 299	23.9	76.1
	Wholesale trade	8 655	27.7	72.3
	Transportation and warehousing	6 113	23.9	76.1
	Accommodation and catering	5 936	24.6	75.4
	Information and communication	3 802	9.3	90.7
	Real estate	1 411	28.4	71.6
	Professional, scientific and technical activities	7 421	13.3	86.7
	Administrative and support activities	6 867	28.4	71.6

  Table V presents a profile of the ten respondents.

	Resp 2	Raw materials procurement	Agrifood (France)	2h09 min
	Resp 3	Corporate Purchasing	Energy (France)	45 min
		Manager
	Resp 4	Head of Procurement	Furniture and wood (France)	1h20 min
	Resp 5	European innovation	Food and beverage FMCG	50 min
		procurement	(Netherlands)
	Resp 6	Head of Technical	Pharmaceutical and biological	1h15 min
		Procurement	(France)
	Resp 7	Procurement Head	FMCG (France)	45 min
	Resp 8	Purchasing Manager	European manufacturer of	1h30 min
			domestic and industrial heating
			appliances (France)
	Resp 9	Head of Procurement	European food and snacks (UK)	1h
	Resp 10	Chief Procurement Officer	Multinational contract food	1h10 min
			service firm (UK)
	Table V. Respondent's list
	Respondent's	Respondent's position	Sector (Country)	Duration of
	code			interview
	Resp 1	Sourcing Manager,	Pharmaceutical (Germany)	1h04 min
		Packaging

Acknowledgment: We are very thankful to the anonymous reviewers who help us a lot to improve our study.