JPS60141752A - Plastic molded article having excellent resistance to printing - Google Patents

Abstract

PURPOSE:To provide a molded article having excellent adhesivity to a sublimable ink and resistance to printing, and high heat resistance, mechanical strength and abrasion resistance, by compounding a polybutylene terephthalate with a polyethylene terephthalate or polycarbonate and an inorganic material. CONSTITUTION:The objective molded article is produced from a composition obtained by compounding (A) >=50% polybutylene terephthalate with (B) <=50% polyethylene terephthalate, polycarbonate or their mixture and (C) <=50% inorganic material as an auxiliary additive. The component C is e.g. talc, mica, titanium oxide, calcium hydroxide, barium sulfate, calcium carbonate, or glass fiber.

Description

[Detailed description of the invention] The present invention has excellent heat resistance, mechanical strength, wear resistance, etc.
In order to obtain clearly printed plastic molded products,
Using sublimation ink, the print material has close contact with the ink,
By selecting an appropriate material composition with excellent compatibility,
Not only does this molded product enable printing, which was previously considered difficult, but it also has excellent heat resistance, printing resistance, oil resistance, etc., so the molded product can be used in fields other than those where its use was previously limited. It is related to expanding and economically producing molded products that fully satisfy the above-mentioned functionality.

Specifically, in order to obtain a plastic molded product printed with sublimation ink and having excellent printing resistance, the main material of the molding material is polybutylene terephthalate, polycarbonate, or a mixture thereof, and talc or mica is used as an auxiliary material. , titanium oxide, calcium hydroxide, barium sulfate, glass IIH, and other inorganic materials are used.

In the composition of the above plastic molded product, the main material and the auxiliary material are polymer blended, with the main material polybutylene terephthalate being 50% or more and the auxiliary material polyethylene terephthalate, polycarbonate, or a type of mixture thereof being 50% or less. The present invention relates to a molded article in which a plastic material having a composition in which an inorganic substance is added in an amount of 50% or less of the sub-material is printed using a sublimation ink after molding.

Traditionally, thermoplastic resins such as heenol, melamine, and unsaturated polyester have been widely used for parts and housings that require heat resistance and mechanical strength, but recently they have been replaced with moldability and processability. Resins called engineering plastics, such as thermoplastic resins polybutylene terephthalate and polyethylene terephthalate, are often used because they have excellent properties, can be designed in a wide range of shapes, and can reduce costs through mass production.

However, these resins not only have superior physical strength compared to general-purpose thermoplastic resins, but also have superior chemical strength, so they are suitable for applications that require printing, such as letters and pictures, with ink. Adhesion to the base material is difficult, making it difficult to obtain sufficient durability (adhesion, printability, etc.). Therefore, in the present invention, each of these resins has an ester group, and we take advantage of the fact that these resins are easy to dye with disperse dyes and oil-soluble dyes.
A sublimation transfer method is used in which a printing ink made of sublimation ink v1 is printed and is closely attached to a molded article (printed object) and heated to permeate into the molded article. In addition, these polybutylene terephthalate and polyester are crystalline polymers and have a high shrinkage rate after heating, and their fluidity is inferior to that of general-purpose polymers after heating, so the adhesion, appearance, and dimensional accuracy of the molded product may be affected. Inferior.

In addition, these engineered plastics are often used in harsh environments and are required to have heat resistance, chemical resistance, and abrasion resistance. In the present invention, in order to satisfy many of these conditions, we researched the composition of plastic molded products, and by combining materials with the appropriate composition and range described below with sublimation ink, we can obtain true printed matter. be.

The present invention will be explained in detail below.

The first feature of the present invention is its material composition.

Materials used in the present invention Polybutylene terephthalate is used as the main material. This polybutylene terephthalate is suitable for injection molding, which is the main method of this processing method, because it has superior fluidity compared to polyethylene terephthalate or polycarbonate as an auxiliary material, and it also has excellent mechanical strength and physical properties. In addition, this polybutylene terephthalate is used in key tops of computer keyboards, parts of microwave oven housings, and parts of housings for sewing machines and power tools. Another reason for this is that it has excellent chemical properties and can be molded into complex shapes. However, compared to general-purpose plastics such as polyethylene, polypropylene, and polystyrene, it has a higher melting point and crystallization temperature, and the fluidity of the resin when melted is inferior. Therefore, in injection molding, it is difficult to maintain the shape and dimensions of the mold on flat parts such as housings, so during the injection molding process, high-pressure, high-speed injection, strong mold clamping pressure, and cooling retention time are required. Maintain shape stability by increasing size. However, these methods tend to cause warpage and sink marks due to variations in molded product processing conditions, and increased costs due to increased cycles. When these warps and sink marks are later subjected to transfer printing using sublimation printing ink, the adhesion with the transfer foil surface directly depends on the quality of the printing.

In addition, printed molded products are often exposed to harsh environmental changes,
Stability over long periods of time, heat resistance, abrasion resistance, oil resistance, and chemical resistance are also required to be far more stringent than those of general-purpose plastics.

In order to deal with these problems, the present invention uses polyethylene terephthalate as the main material, polyethylene terephthalate, polycarbonate, or polyethylene terephthalate, which has lower fluidity after melting but has excellent heat resistance and less sink marks and warp after crystallization. A polycarbonate mixture is used as an auxiliary material, which is blended into the main material polybutylene terephthalate. If the amount of this latter sub-material is increased, the fluidity during injection molding will decrease, resulting in a decrease in moldability for computer key tops, etc., which is the main object of the present invention.

Therefore, the mixing ratio of the main material and the sub-material is such that the sub-material does not exceed 50%. Preferably, the amount of the auxiliary material is in the range of 10 to 40%. These sub-materials have excellent compatibility when blended with polybutylene terephthalate, the main material, and have ester groups in their molecules, making them highly compatible with disperse dyes, which are the main component of sublimable inks. Because of the excellent printability, printability and adhesion were also maintained, and the addition of polyethylene terephthalate actually improved them.

do. In addition, the secondary materials polyethylene terephthalate and polycarbonate have a higher melting point and glass point shift than polybutylene terephthalate, so as the amount added increases, the heat resistance of the molded product improves.

In particular, computer keycaps are required to have print stability over time and to withstand relatively high temperature environments. Improving the heat resistance of molded products is required to prevent printing ink from increasing in temperature and migration after time. It is also effective in preventing. Once the ink has penetrated into the molded product (printed material)
This is because the ink is held in that position as long as the molecular movement and crystals do not loosen. Furthermore, since these sub-materials cause less warpage and sink marks after molding than polybutylene terephthalate, they are also effective in improving the stability of the printing surface of the printing material, which is a problem during printing.

By the way, the feature of the present invention is that talc, acid, etc. are added as auxiliary materials to the blend of the main material r1 and the auxiliary materials.

Inorganic substances such as titanium chloride, sulsulam hydroxide 1, barium sulfate, sulsulam carbonate, and glass fiber are used as secondary materials.
Add in a range of about 0% or less. Preferably the secondary material is 10
5% within the range where the inorganic substance of the auxiliary material impairs fluidity.
A range of ~10% is suitable. The reason for adding these inorganic substances is that when added to such a crystalline polymer, thermal conductivity is improved and crystallization is accelerated, thereby shortening the injection molding cycle and improving productivity. Dimensional accuracy is stable because the heat shrinkage rate during molding is small. When polyethylene thalphthalate is added as an auxiliary material, it acts as a core material to promote crystallization. This is for reasons such as reducing warpage and sink marks of molded products caused by crystalline resin to improve printing stability.

Furthermore, if the inorganic auxiliary material is added at a high concentration of 50% or more, it may lead to a decrease in fluidity during molding, a decrease in printing density, etc.

The molded product according to the present invention is molded by injection molding using these molding materials that are easily sublimated and then subjected to gravure printing or silk printing with an ink containing a sublimable dye mainly composed of disperse dyes or hot water dyes. The transfer foil is placed in close contact with the molded product and heated at around 2,000 ℃ for several minutes, allowing the dye to penetrate from the transfer foil into the molded product through sublimation, while printing letters and patterns.

At this time, these molded products have improved heat resistance compared to single polybutylene terephthalate molded products due to the material blending effect, and are also characterized by less thermal deformation during the above-mentioned heat transfer printing, further improving printing stability. .

These molded products not only function as engineering plastics, but also have excellent abrasion resistance and adhesion because they are printed with ink through sublimation transfer, and are useful for computers, calculators, key tops of typewriter keyboards, microwave ovens, etc. It can be put to practical use in the housings of other electronic devices, and has great economical effects.

Examples of the present invention will be shown below.

<Example> Polyethylene terephthalate (mp = 2
306C), the secondary material boethylene terephthalate (m
P=260 G) was blended with a polymer, and a material to which talc was added as an inorganic auxiliary material was sufficiently melted and mixed using an extruder to prepare pellets.

At this time, a plate-shaped molded product with a size of 5×5 cm and a thickness of 2 mm was obtained using an injection molding machine by changing the blending ratio of the main material, sub-materials, and auxiliary materials. A transfer foil printed with a sublimable ink using a sublimable dye made of a disperse dye was closely attached to the molded product, and then heated and pressed at a temperature of 200oC to perform permeation printing by transfer.

<Example 2> 20 wt% polycarbonate as an auxiliary material of pressure molding material
Added pellets] were prepared, injection molded and then transfer printed.

(Table 1) Formability and printability depending on material r1 blending ratio (Table 2)
Moldability and printability depending on material blending ratio 13- (Table 3) Moldability and printability depending on material blending ■, - Shunshun) April 26, 1959 Director of the Japan Patent Office fiQ Kazuo Wakasugi 1. Indication of the case 1982 Patent Application No. 249663 2. Name of the invention Plastic molded product with excellent printing resistance 3. Person making the amendment Relationship to the case Patent applicant address: 1-5-1 Taito, Taito-ku, Tokyo Name (319)
) Engraving of the full statement of Toppan Printing Co., Ltd. (no changes to the contents)

Claims (1)

[Claims] 1) In order to obtain a plastic molded article with excellent printing resistance printed with sublimation ink, the molding material is polybutylene terephthalate, the auxiliary material is polyethylene terephthalate, polycarbonate, or a type of mixture thereof; Furthermore, a plastic molded product with excellent printing resistance is characterized by using a material to which an inorganic material is added as an auxiliary material. 2) 50% of the above main material polybutylene terephthalate
The above is a plastic whose composition is a polymer blend of the main material and the sub-material, in which the sub-material polyethylene terephthalate, polycarbonate, or a type of mixture thereof is added in an amount of 50% or less, and an inorganic substance is added in an amount of 50% or less of the sub-material. A plastic molded article with excellent printing resistance according to claim 1, characterized in that the plastic molded article is made of the material. 3) The plastic molded article with excellent printing resistance according to claims 1 and 2, wherein the inorganic substance is talc, mica, titanium oxide, rhusium hydroxide, barium sulfate, rhusium carbonate, or glass fiber.