Plastic dyeing process supporting dyeing of products in small lots of required quantity and color and solving the problems of cost and inventory controlMURAKAMI Co.,Ltd


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Plastic dyeing process for color toning to the required color

Points to remember

  • Develop technology for the plastic dyeing process using the experience and knowledge about dyes
  • Foresight and flexibility to shift the core business to dyeing process for plastics

Murakami Co., Ltd. specializes in the dyeing process of plastics. They have a proprietary technology for coloring where plastics ranging from general purpose plastics to super engineering plastics and 3D modeling plastics, are dyed in the molded state.

The company was established as Murakami Dye and Chemicals Co., Ltd. in 1957 at Kyoto. Since its founding, as the company was selling industrial chemicals and synthetic organic dyes for textile dyeing, they have a track record and extensive knowledge of dyes. Based on this track record and knowledge, along with the readiness to take up new challenges, they decided to develop the technology for the dyeing process of plastics.

It all started 20 years back when the representative director of the company, Mr. Kenji Murakami attended the “Networking event with other companies” which was popular in those days. The president of a plastic molding maker who attended the event asked, “Can dyeing process be used for plastics?”. Taking a cue from this, they slowly shifted the core business to the research and development of plastic dyeing from 1995.

What exactly is plastic dyeing process technology?

Unlike “Material coloring” and “Painting”, which are the conventional coloring methods, plastic dyeing process is a technology in which the dye is made to penetrate inside a plastic resin molded product by utilizing the affinity of dyes to plastics.

“Material coloring” and “Painting”, which are the conventional plastic coloring methods, have the advantages and disadvantages described above.

The main difference between conventional coloring methods and the dyeing process. Resin molded products can be dyed in small lots using the dyeing process. Small and medium-sized enterprises engaged in resin molding often require colored molded products in small lots. When purchasing “Colored material” resins, it has to be purchased in large quantities ranging from several hundred kilograms to one ton. It poses a problem concerning cost and inventory control. In “Painting”, components are colored after molding, peeling off of the coating film and inability to paint certain types of resins is a bottleneck. It can be said that the “Dyeing process” can overcome such disadvantages of the conventional coloring methods. In the case of the dyeing process, significant cost reduction can be expected by handling small lots of the required quantity and color.

The company took approximately four years to perfect the technology of the plastic dyeing process through repeated trial and error. Since the dyeing process technology is the proprietary technology of the company, it is named as MTP (abbreviation for Murakami Thermo Pressure) plastic dyeing.

In addition to supporting small-lots, MTP plastic dyeing has the following advantages.

Advantages of MTP Plastic Dyeing

The company has given importance to safety and environmental consideration through the development of MTP plastic dyeing. The high level of safety is also evident from the fact that the process has met all regulations such as RoHS, REACH, and EU. Since the dye penetrates inside the resin during the dyeing process, there is no concern of peeling off of the coating unlike painting and allows the process to be used in medical facilities. Bioplastics can also be dyed, and the technology can also contribute to the manufacturing of products that do not burden the natural environment.

At present, the dyeing process has the following disadvantages: Discoloration in harsh environments such as outdoors and poor resistance to light. When ABS resins used in injection molding are dyed, fogging and scratches are conspicuous. Color transfer after dyeing of silicone resins. In the future, these disadvantages will be overcome by finding solutions through repeated verification tests.

At present, the company is engaged in a wide range of business transactions with manufacturers of apparel, medical products and industrial parts for the dyeing process technology. In the future, they are seeking to do business with companies dealing in resin molded products in general over a wide range of applications.

Mr. Murakami of the company said, “I hope that by participating in exhibitions, we will be able to come across methods to utilize the dyeing process in ways that we have not imagined”. The need for the plastic dyeing process that can be used for small lots is still expanding endlessly.

Interview Date: March 4, 2019


company information

Since our founding, we have engaged in selling dyes and chemicals for textiles, and have thereby accumulated extensive knowledge and experience. With Japan’s only business structure specialized in plastic dyeing, we have succeeded in dyeing multiple resins, which had been considered impossible. Based on our dyeing/toning techniques, we will unlock new opportunities for plastic products.

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