Miljøprojekt, 1039 – Mapping and development of alternatives to chlorinated lubricants in the metal industry (KLORPARAFRI)

Mapping and development of alternatives to chlorinated lubricants in the metal industry (KLORPARAFRI)

1 Introduction

1.1 Background
1.2 Objective
1.3 The project

1.1 Background

The fields of application of chlorinated paraffins are many. One of the main fields are as extreme pressure additives in metal working lubricants (1). The chlorinated paraffins are chemically and physically stable and have excellent lubricating properties at high pressure. These characteristics in combination with low production costs make the substances technically and economically well suited as high pressure additives in lubricants for metal working.

Chlorinated paraffins are complex mixtures of chlorinated n-alkanes characterized by an average carbon chain and chlorination degree. The chain length of commercially available chlorinated paraffins varies from 10 to 30 carbon atoms. From the number of carbon atoms in the carbon chain, the chlorinated paraffins are divided into three main groups: C_10-13 – short-chained chlorinated paraffins, C_14-17 – medium-chained chlorinated paraffins and C_18-30 – long-chained chlorinated paraffins (2). Both short- and medium-chained chlorinated paraffins are used as high pressure additives in metal working lubricants. Due to reduction initiatives for short-chained chlorinated paraffins in the EU, there has been a change within the EU towards an increased use of medium-chained chlorinated paraffins in metal working lubricants (3).

Chlorinated paraffins are suspected to cause harmful effects on human health. The EU classification of short-chained chlorinated paraffins (alkanes, C10-13, chloro, CAS No. 85535-84-8) regarding health effects is carcinogenic in category 3 (Carc3) with risk phrase R40 ”Limited evidence of a carcinogenic effect” (4). This classification is based on animal test data (5). A risk assessment of medium-chained chlorinated paraffins (alkanes, C14-17, chloro, CAS No. 85535-85-9) is presently being carried out in the EU. In the latest draft for human risk assessment of medium-chained chlorinated paraffins it is proposed that the substance group should be classified as toxic to reproduction in category 3 (Rep3) with risk phrases R63 ”Possible risk of harm to the unborn child” and R64 ”May cause harm to breastfed babies” in addition to R66 “Repeated exposure may cause skin dryness or cracking”. The classification is based on animal test data (3).

The chlorinated paraffins are persistent and bio-accumulative substances. This is reflected in the fact that the substances are found widespread in the external environment, including sediments, aquatic organisms and marine mammals. The substances have also been found in foodstuffs and mother's milk (2,3). In the EU, short-chained chlorinated paraffins (CAS No. 85535-84-8) are classified as dangerous for the environment (N) with the risk phrase R50/53 ”Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment” (4). Medium-chained chlorinated paraffins (CAS No. 85535-85-9) exhibit similar effects in the aquatic environment. In the draft EU risk assessment of the substance group in the external environment, an environmental classification N;R50/53 similar to that for short-chained chlorinated paraffins is proposed (3).

Long-chained chlorinated paraffins are currently undergoing a health and environmental risk assessment in the EU.

Chlorinated paraffins, including both short-, medium- and long-chained chlorinated paraffins, are included in the Danish Environmental Protection Agency's list of unwanted substances due to the serious health and environmental properties of the substances (6).

In the past decade, a number of projects have been carried out in the Danish metal industry aiming at finding alternatives to chlorinated paraffins in metal working fluids. Thus, there has been a substantial reduction in the use of chlorinated lubricants by Danish large-scale consumers in the metal industry. Chlorinated metal working lubricants for cutting operations such as milling, screw-cutting and drilling have gradually been completely substituted. Technically satisfying non-chlorinated lubricants for these types of metal working processes are now readily available on the market. For non-cutting operations, particularly demanding processes such as forming stainless steel and titanium, chlorinated metal working lubricants are still widely used. The reason for this is that so far there have not been technically satisfactory alternatives available on the market (7,8).

Thus, chlorinated metal working lubricants are still used in the Danish metal industry in demanding non-cutting operations in stainless steel etc. At the same time, metal working processes making heavy demands on the lubricants become more and more common in the industrial production due to demands for material and energy savings, increased productivity, improved quality etc. Therefore, the need for lubricants to be used under very demanding production conditions is increasing (9).

1.2 Objective

The overall objective of this project is to promote the complete substitution of chlorinated paraffins used in lubricants for metal working by technically acceptable and health and environmentally improved alternatives. As the use of chlorinated lubricants continues especially in heavy-duty metal forming operations in stainless steel and in other metals, the project concentrates on these types of operations.

The specific objectives of the project are:

Mapping of existing non-chlorinated lubricant technology alternatives for heavy-duty metal forming, especially deep-drawing, stamping and extrusion in stainless steel and other metals.
Technical testing of alternatives
Environmental and health assessment of alternatives
If possible, production maturation of promising alternative lubricants
Communication of project results to relevant target groups

1.3 The project

The project has been divided into five phases.

Phase 1	Setting up technical criteria for alternative lubricants Setting up health and environmental criteria for alternative lubricants.
Phase 2	Mapping of existing alternative lubricants by contact to international lubricant suppliers and the chemical industries.
Phase 3	Testing of alternative lubricants in simulating and process technical tests. Health and environmental screening of proposed lubricant alternatives.
Phase 4	Testing of selected alternatives in production. Environmental and health assessment of compounds typically found in non-chlorinated lubricants for heavy-duty metal working. Exposure assessment in the working environment at a screening level of critical compounds in non-chlorinated lubricants for heavy-duty metal working.
Phase 5	Communication of project results.

Phase 1

In phase 1, technical criteria were set up for lubricants. This was done in order to be able to identify lubricants with potentially suitable lubricating properties in the metal forming processes in focus and secondly to identify lubricants with suitable properties regarding corrosion, stability, application and degreasing etc.. A stepwise selection of lubricants was planned with an initial identification of suitable lubricants based on supplier information, secondly an identification of promising lubricants based on results in simulating technical tests and thirdly an identification of the most suitable lubricants for testing in the production equipment at Danfoss A/S.

Also in phase 1, health and environmental criteria for lubricants were set up. This was done in order to define an acceptable lubricant in a health and environmental context and to avoid production tests of lubricants with obvious unwanted health or environmental properties.

Phase 2

A mapping of existing non-chlorinated lubricant systems for heavy-duty metal forming in stainless steel was performed in phase 2 by contacting international lubricant suppliers and suppliers of lubricant additives.

Phase 3

In phase 3, the non-chlorinated lubricants for which supplier information showed that they possessed suitable lubricating properties in the metal processes in focus, and for which the supplier agreed to forward a test probe, were tested in simulating and process technical tests.

Simultaneously, a health and environmental screening of proposed non-chlorinated lubricants was performed in order to get an overview of the health and environmental characteristics compared to chlorinated lubricants and to identify lubricants with obvious unwanted health and environmental properties prior to the production tests of selected lubricants.

Phase 4

Selected lubricants exhibiting promising lubricating properties in the simulating and process technical tests were tested in production at Danfoss A/S.

A health and environmental assessment of selected components typically occurring in non-chlorinated lubricants was performed. This was done in order to provide an overview of the health and environmental data platform for components in non-chlorinated lubricants and to perform assessments of inherent health and environmental properties of the components based on available data.

In addition, exposure assessments at a screening level of selected components in non-chlorinated lubricants were performed.

Phase 5

In phase 5, the project results were communicated.

Project partners

Partners in the project has been Danfoss A/S, Esti Chem A/S, the Department of Chemistry of the Technical University of Denmark and CETOX (Centre for Integrated Environment and Toxicology).

Danfoss A/S is the largest industrial group in Denmark and one of the leading companies in the world within refrigeration and air conditioning, industrial controls, heating and water and motion controls. Danfoss A/S produces a long line of products by forming stainless steel.

Esti Chem A/S is part of the Dow Chemical Company. Esti Chem A/S has specialised in development of synthetic ester based raw materials for formulation of industrial lubricants. Substitution of chlorinated lubricants in metal working has long been a high-priority development area for Esti Chem A/S.

The Department of Chemistry of the Technical University of Denmark is working in the area of inorganic chemistry, molten salts chemistry and materials chemistry including relations between chemical and lubricating characteristics. For several years, the department has been engaged in projects dealing with the development of non-chlorinated lubricants for metal working and has expert knowledge on tribological tests. Tribology is the science of lubrication, theory and technique.

CETOX is a formal cooperation between the Danish Toxicology Centre (DTC) and DHI Water and Environment. The working area of CETOX is consultancy for industry and authorities in the area of integrated human toxicology and eco-toxicology. Both DTC and DHI are independent, non-profit technological service institutes approved by the Danish Minister for Science, Technology and Development.