kuraray


The Story of the Birth of New Products(EVAL)

EVAL - Revolutionizing the Barrier Market

Commercialization of the high performance resin EVAL, which was developed for the first time in the world by Kuraray, took fifteen long years to accomplish from the start of serious basic research, undertaken with the aim of improving Poval resin, in 1957. Since it has the best gas barrier properties (exhibits the best non-permeability properties against gas such as oxygen) among all types of resins, and thus prevents the deterioration of whatever it may be containing, EVAL has successfully prevailed in the market, finding a numerous applications in containers for mayonnaise and ketchup, or for wrapping food such as flaked fish and miso, to name just a few. Even broader ranges of applications for this resin are being developed including use in artificial kidneys and fuel tanks for automobiles. In more ways than can be readily mentioned, EVAL resin has become crucial for modern living.

The Reformulation of Poval as the Starting Point

EVAL material.

Supermarkets began to proliferate rapidly across Japan in the late 1950s, thanks to the onset of high economic growth. While plastic materials such as polyethylene and vinyl chloride were in the public limelight, there grew need for food packaging material which were light weight and capable of preserving foods longer. Against this background, the company launched a full fledged research project focused on deriving plastics from vinyl acetate(*1)(the raw material used to create Poval) in 1957.

In order to make a plastic resin by reformulating (modifying) Poval, it was first necessary to reduce the hydrophilic nature of the material, which is the best property of Poval resin. The R&D team found that only ethylene brought a good result when copolymerizing(*2)various kinds of monomers(*3). The crystalline structure of the polymer would break down during copolymerization depending on the monomer selected and the resulting polymer would become useless as a plastic except in the case of ethylene copolymerization, which was a rare type of polymer that retained its crystalline structure in all regions.

It was not clear if ethylene copolymers could be used as plastics at the time, because it was not easy to handle and was expensive. However, a major discovery was made while research continued thanks to a fortuitous factor. This was the discovery of the very high performance gas barrier property of the material. Although the gas barrier properties of Poval became lower as humidity rose, the hydrophilic nature of Poval was suppressed if it was copolymerized with ethylene. This made it possible for the material to retain high performance barrier properties under normal conditions of humidity, something that had not been possible before. This was the moment when the EVOH (ethylene vinyl alcohol) copolymer was born. This high functionality resin later came to be called EVAL.

Barriers to Commercialization

The device originally used to measure
the oxygen permeability of EVAL resin.

The company first started a joint developing project with a major food processing company to commercialize EVOH in 1964. In doing so, the first difficult problem encountered was determining the extent of gas permeability with sufficient precision. The first trials undertaken to evaluate permeability consisted of checking the surface color of soy bean paste called miso wrapped in a bag made of EVOH film, then measuring the oxygen concentrations in a bag filled with nitrogen. However, these methods of evaluation had their limitations for precision. Thus, the company research group made a glass measuring device by hand in cooperation with a university study group after diligent effort, and went about measuring permeability for two years. As a result, the research group was able to demonstrate the excellent gas barrier properties of EVOH film. The company submitted a basic patent application for food packaging based on the test results in March 1966, and made preparations to begin commercializing EVOH. The discoveries made during this process played an important role for years to come.

Mayonnaise containers.

Despite the granting of the patent, serious disputes continued among the management for years questioning whether to go ahead or not with R&D into mass production technology, because a huge amount of investment was required. Although, there were 30 members in the R&D team at first engaged in the development of mass production technologies, the number of researchers was drastically reduced. At one point, things reached such an extreme that there were only two researchers assigned to work on the film application aspect of development.

Under such circumstances, company President Soichiro Ohara concluded a guideline in 1967 that "it is easy to cancel a project, but if we contemplate the corporate system of the future, cancellation can wait one more year. Consider it deeply". This encouraged the R&D team. In 1968, only twelve months later, the prospects for commercializing EVOH were successfully determined, and a full scale test plant was completed for 200kg production per day in 1969. The trade name EVAL was given to the product at the same time. Thus, it took fifteen long years from the start of basic research and accumulation of much knowledge by the R&D team before EVAL resin was first commercialized in 1972.

Two Strokes of Good Fortune

EVAL garnered a lot of attention ever since it was first introduced on the market as a food packaging material with great potential, especially since its appearance coincided with the dawn of the plastics era. In addition to excellent gas barrier properties, it had a high level of safety because it did not contain any additives such as plasticizers or stabilizers, which also contributed to its being highly regarded as environmentally friendly. The expectations of EVAL were extended even more because it fitted food packaging better than other materials prevailing at the time such as plastic bottles or jars.

The market for EVAL developed very quickly as it came to be used in an ever widening range of applications such as packaging film for preserved foods such as katsuokezuribushi (flaked bonito - used in Japanese cooking) and miso, food containers for mayonnaise, ketchup, soy sauce, and other types of sauces and edible oils, as well as in pharmaceutical containers, through the combination with polyethylene or polypropylene. EVAL opened the medical market by being successfully used in the development of artificial kidneys through the use of hollow fiber membranes(*4)

There were two strokes of good fortune behind this success story. One was concerned with thermoforming technology in which EVAL resin could be melted and extruded at temperatures ranging between 200 to 220℃. Although the melting point(*5)of Poval resin is around 240℃, which is close to the point where thermal decomposition of the material occurs, EVAL resin enabled the use of a less expensive method of extrusion because the melting point of EVAL resin was approximately 60℃ lower than its thermal decomposition point. This proved to be a significant merit of EVAL resin.

The other fortuitous factor was the development of a technical innovation known as coextrusion technology(*6)Normally, users had to perform film laminate processing, but coextrusion techniques made it possible to omit such processing. Many applications of EVAL resin became available as a result of this technology, and the demand for EVAL resin increased tremendously as a result.

EVAL Spreads Around the World

Balloons made of EVAL resin.

EVAL resin grew to become a major source of revenue for the company and to lead the way in the globalization of the company, as well.

When exports of EVAL resin to the U.S. began in full scale in 1982, the trade name EVAL was already well known from coast to coast and demand grew quickly. This led to the founding of the Eval Company of America (EVALCA) as a joint venture with Northern Petrochemical Company (now fully owned by the company). The new company soon assumed local production of EVAL resin in 1983. EVALCA started to produce EVAL resin in Houston, Texas in December 1986. It was decided that the plant should have an initial capacity of 10,000 tons per year based on estimates for a high growth rate in the future, even though total annual sales of EVAL at the time was merely 1,000 tons.

This decision brought about a revolution in the huge food container market in the U.S. A similar strategy was adopted in the European market but to a different timetable. Thus, a three-pole system consisting of Japan, the U.S., and Europe was established, thereby further enhancing the ability of the company to respond more flexibly to market needs from a global perspective.

The history of the evolution of EVAL also corresponds to the history of growing concern for the natural environment. Each time an environment issue arose somewhere in the world, whether it was PVC(*7)residue monomer problem that occurred in Japan in 1973, the movement to replace PVDC(*8)and PVC as a result of problems associated with acid rain in Europe in 1980, the revision of the Clean Air Act in the U.S. in 1990, or the introduction of the California Air Resources Board (CARB) Regulations in 1995 also in the U.S., EVAL resin made significant contributions to helping to resolve these problems through its use as an alternative material.

Plastic fuel tank constructed of EVAL resin.

Particularly, the development of plastic fuel tanks (PFT) for automobile, begun in 1992, demonstrated the superior barrier properties of the material by preventing the evaporation of gasoline fuel from the tank, while also at the same time helping to reduce automobile weight. Two years later, PFTs were commercialized for the first time in the U.S., and succeeded thereafter to develop into a new large-scale market.

The company has been pushing ahead with a basic business strategy of EVAL resin, that is, producing it where it is suitable to manufacture and selling it where it is suitable to sell. For example, U.S. production capacity was increased in 1997 to accommodate the strong demand for barrier products in the market including PFT, and European production facilities were upgraded in 2004 with the latest equipment to address environmental concerns.

There is an unlimited range of needs in the world market for barriers of various types beyond those used to prevent the leakage of gas and evaporation of fuel, including barriers for scents or aromas, heat, dirt or grime, as well as light ray. The company is dedicated to providing the most advanced technology available to meet the ever-growing demand for barrier type product and to lead the world of the barrier material market through EVAL resin.

Food samples wrapped in film created using EVAL resin.

  • *1 Vinyl Acetate: Injecting a catalyst with oxygen, ethylene, and acetate in a gaseous state into a reactor will induce a reaction that produces and refines the vinyl acetate. By converting vinyl acetate into a resin, it can be used in such applications as Vinylon fiber, adhesives, laundry starch, artificial lawn material, wood glue, and chewing gum ingredients.
  • *2 Monomers are simple compounds whose molecules can join together to form polymers. While macromolecules are called polymers (poly means many), monomers consist of one molecule (mono means one) only.
  • *3 Polymerization refers to any process in which two or more types of monomers are combined chemically to produce a polymer without changing the basic structure (atomic arrangement) of the base materials. Copolymerization is a process in which more than one monomer is used to produce a copolymer.
  • *4 Hollow fiber: Fiber having a space in the center like a micro tube. It is used for textile material and as a filter to prevent impurities from passing through the fiber.
  • *5 Melting point is the temperature at which a solid substance starts to melt into a liquid.
  • *6 Coextrusion is a film processing method used to extrude two or more materials through a single die with two or more orifices arranged so that the extrudates merge and fuse together into a laminar structure in a state of fusion.
  • *7 PVC: Polyvinyl chloride.
  • *8 PVDC: Polyvinylidene chloride.

(2006)