JPH05279538A - Methacrylic resin molding composition - Google Patents

Abstract

PURPOSE:To provide the subject composition of excellent mold release by mixing a methyl methacrylate polymer with a higher fatty acid amide and a higher fatty acid. CONSTITUTION:This composition comprises 100 pts.wt. methyl methacrylate polymer and 0.02-0.5 pts.wt. mixture comprising a 10-22C fatty acid amide and a 10-22C fatty acid in a weight ratio of 10/90 to 90/10, and at the weight ratio, desirably at a weight ratio of 25/75 to 75/25, a remarkable synergistic effect can be realized. The actual ratio is selected from this range according to the composition, molecular weight, flow, etc., of the methyl methacrylate polymer used. When an excess of the higher fatty acid amide is used, the obtained molding is colored, undesirably. Especially when molded in a mold, the above resin composition shows excellent mold release.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a methacrylic resin composition having excellent processability. In particular, the present invention relates to a methacrylic resin composition having excellent mold releasability at the time of molding using a mold.

[0002]

2. Description of the Related Art Methacrylic resins are used for automobile parts such as meter covers, optical parts such as optical discs and lenses, and electric lamp covers, etc. by taking advantage of their original excellent transparency, weather resistance and good mechanical properties. It is used for lighting parts, etc. These molded products are generally obtained by injection molding, injection compression molding, etc., but in precision mold molding such as optical lenses and optical disks, the adhesion between the molded product and the mold surface becomes extremely high. Mold release failure occurs, resulting in a decrease in productivity.

Therefore, it has been proposed to add various releasing agents to the methacrylic resin. For example, JP-A-61-737
Japanese Unexamined Patent Publication No. 54-54 proposes a resin composition obtained by adding a polyhydric alcohol, a higher fatty acid ester, a higher alcohol, a higher fatty acid, a higher fatty acid amide, and a higher fatty acid metal salt to a methacrylic resin.

[0004]

However, when injection molding is performed using these resin compositions, some degree of mold release performance is recognized, but it is still insufficient. In addition, the release agent and other additives added to the resin migrate to the surface of the resin to stain the surface of the mold or the surface of the molded product and to color the molded product, thereby significantly reducing the commercial value of the molded product.

The present invention provides a methacrylic resin composition which overcomes the drawbacks of conventional release agents and exhibits an excellent release effect with a smaller amount.

[0006]

According to the present invention, 100 parts by weight of a methyl methacrylate polymer is added with a higher fatty acid amide having 10 to 22 carbon atoms and a higher fatty acid having 10 to 22 carbon atoms in a weight ratio of 10/90 to 90. The present invention relates to a molding methacrylic resin composition containing 0.02 to 0.5 part by weight of / 10.

The term "methyl methacrylate polymer" as used in the present invention means methyl methacrylate homopolymer, or methyl methacrylate and 20% by weight or less of acrylic acid ester or methacrylic acid ester, acrylic acid, methacrylic acid. It refers to a copolymer with acid, styrene, acrylonitrile, diene rubber, glutaric anhydride, glutarimide, or the like. The acrylic ester is methyl acrylate, ethyl acrylate, butyl acrylate, etc., and the methacrylic ester is ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, etc.

Examples of the higher fatty acid amide having 10 to 22 carbon atoms of the present invention include lauric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, erucic acid amide and N-oleyl stearoamide.

If the higher fatty acid amide has less than 10 carbon atoms, it has a high volatility and is volatilized during molding, and a sufficient releasing effect cannot be obtained. On the other hand, those having more than 22 carbon atoms are not preferable because they have low compatibility with the methyl methacrylate-based polymer and are likely to appear on the resin surface, causing mold stains and molded product stains.

Examples of the higher fatty acid having 10 to 22 carbon atoms of the present invention include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid and linolenic acid.

If the higher fatty acid has less than 10 carbon atoms, it has a high volatility and is volatilized during molding, so that a sufficient releasing effect cannot be obtained. On the other hand, those having more than 22 carbon atoms are not preferable because they have a low compatibility with the methyl methacrylate polymer and thus are likely to appear on the resin surface and cause mold stains and molded product stains.

In the present invention, when the higher fatty acid amide and the higher fatty acid are used in a ratio of 10/90 to 90/10, preferably 25/75 to 75/25, a remarkable synergistic effect is exhibited. .. Within this ratio,
It is selected according to the composition, molecular weight, fluidity, etc. of the methyl methacrylate polymer used. If the amount of the higher fatty acid amide is too large, the molded article is colored, which is not preferable.

The total amount of the higher fatty acid amide and the higher fatty acid is 0.02 to 0.5 parts by weight, preferably 0.05 to 0. 0, based on 100 parts by weight of the methyl methacrylate polymer.
2 parts by weight. If the total amount of these is less than 0.02 parts by weight, the release performance is insufficient, and the surface layer of the molded product is likely to peel off or crack. On the other hand, if the addition amount exceeds 0.5 parts by weight, the molded product is colored, and the surplus mold release agent adheres to the mold surface, resulting in a dirty and contaminated molded product, which is not preferable. .

A well-known method can be used to make the composition by incorporating the higher fatty acid amide and the higher fatty acid into the methyl methacrylate polymer used in the present invention. For example, there is a method of kneading each component in a molten state, and the melt kneading is not limited to a method using a commonly used kneading device such as a single-screw or twin-screw extruder, various kneaders, and injection. There is a method of directly kneading during a melt processing operation such as molding and extrusion molding.

Further, the higher fatty acid amide and the glycerin monoester of the higher fatty acid are added to and mixed with a monomer or syrup containing methyl methacrylate as a main component, and the mixture is subjected to a bulk polymerization method, a suspension polymerization method, There are known methods such as emulsion polymerization and solution polymerization.

The methacrylic resin composition of the present invention includes antioxidants such as well-known hindered phenolic antioxidants, phosphorus antioxidants and sulfur antioxidants, ultraviolet absorbers and hindered amine type photopolymers. Weathering agents such as stabilizers,
Flame retardants, colorants, pigments and the like can be added, and further, reinforcing fibers such as glass fibers and inorganic fillers can be added depending on the purpose.

[0017]

The methacrylic resin composition of the present invention is
Compared with the conventional methacrylic resin, it has excellent releasability when molded by using a mold, and also has excellent transparency and weather resistance inherent to the methacrylic resin. Therefore,
It is suitable for molding molded articles having complicated shapes such as automobile parts such as meter covers, optical parts such as video disks and lenses, lighting parts, OA equipment parts, etc. using a mold.

[0018]

The present invention will be further described with reference to the following examples. The evaluation methods used in the examples are as follows. -Releasability: 25 mm x 76.5 mm x 3 in an injection molding machine (M-140SJ type manufactured by each machine manufacturer) with a capacity of 13 ounces.
Attach a 2 mm ASTM test piece mold, molding temperature 260
° C., injection pressure 80 kg / cm ² G, under the conditions of mold temperature 60 ° C., 60 seconds cycle, have created a continuous 40 times the test piece.
It was expressed by the ratio of the number of defective products such as cracks and cracks in the molded product at this time. Stainability: Immediately after completion of the above-mentioned molding, the state of cloudiness on the surface of the mold (mirror surface part) was visually observed, and when no cloudiness was observed, it was rated as O, and when there was cloudiness, was rated as X. -Appearance: The stains and coloring of the molded product were visually observed.

Example 1 100 parts of granular methacrylic resin obtained by suspension polymerization (SUMIPEX B LO, manufactured by Sumitomo Chemical Co., Ltd.), 0.025 part of stearic acid amide and 0.025 part of stearic acid.
After being mixed with a Henschel type mixer, the mixture was pelletized using a vent type extruder having a screw diameter of 40 mm. The pellets were evaluated. The results obtained are shown in Table 1.

Examples 2 to 5, Comparative Examples 1 to 4 Example 1 was repeated except that the amounts of stearic acid amide and stearic acid added were changed as shown in Table 1.
The results obtained are shown in Table 1.

Example 6 Example 2 was repeated except that palmitic acid amide was used instead of stearic acid amide. The results obtained are shown in Table 1.

Example 7 Example 2 was repeated except that palmitic acid was used instead of stearic acid. The results obtained are shown in Table 1.

[0023]

[Table 1]

Front page continuation (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // G02B 1/04 7132-2K

Claims (1)

[Claims] 1. A higher fatty acid amide having 10 to 22 carbon atoms and 1 carbon atom in 100 parts by weight of a methyl methacrylate polymer.
Higher fatty acid of 0 to 22 in weight ratio 10/90 to 90/10
A molding methacrylic resin composition containing 0.02 to 0.5 part by weight.