JPH06184390A - Methacrylic resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition having excellent mold release performance by incorporating both pentaerythritol or an analogue thereof and a higher fatty acid into a methyl methacrylate polymer. CONSTITUTION:This resin composition comprises 100 pts.wt. methyl methacrylate polymer and 0.02-0.5 pt.wt. mixture of at least one compound selected from pentaerythritaol and analogues thereof represented by formula I or V and a 10-22C fatty acid in a weight ration of 10/90 to 90/10. In formula I, X<1>, X<2>, X<3>, and *<4> each is H or a group respesented by formula II (wherein R is a 10-22C hydrocarbon group), formula III (wherein (f) is 1-5), or formula IV (wherein (g) is 1-5). In formula V, X<5>, X<6>, X<7>, X<8>, X<9>, X<10>, X<11>, and x<12> have the same meaning as X<1> to X<4> and (n) is 0-3.

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]

BACKGROUND OF THE INVENTION Methacrylic resins are used in 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. Used for lighting parts.
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 release agents to the methacrylic resin. For example, Japanese Patent Laid-Open No. 61-73754
In the publication, methacrylic resin, polyhydric alcohol,
Resin compositions to which higher fatty acid esters, higher alcohols, higher fatty acids, higher fatty acid amides, and higher fatty acid metal salts have been added have been proposed.

[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]

The present invention is based on the following [Chemical formula 3] with respect to 100 parts by weight of a methyl methacrylate polymer.
Alternatively, at least one selected from the pentaerythritols represented by [Chemical formula 4] and a higher fatty acid having 10 to 22 carbon atoms in a weight ratio of 10/90 to 90/10, 0.02 to 0.5
The present invention relates to a methacrylic resin composition containing parts by weight.

[0007]

[Chemical 3]

In the formula, X ¹ , X ² , X ³ and X ⁴ are ones shown in the following [External 2].

[0009]

[Outside 2]

[0010]

[Chemical 4]

Where X ⁵ , X ⁶ , X ⁷ , X ⁸ , X ⁹ ,
X ¹⁰ , X ¹¹ and X ¹² are the above X ¹ , X ² , X ³ and X ⁴
And n is 0 to 3.

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.

The pentaerythritols represented by [Chemical formula 3] or [Chemical formula 4] of the present invention include, for example, monopentaerythritol, dipentaerythritol, tripentaerythritol, tetrapentaerythritol, and pentapentaerythritol. Each ester compound of pentaerythritol and a carboxylic acid having a hydrocarbon group R having 10 to 22 carbon atoms such as lauric acid, myristic acid, stearic acid, behenic acid, oleic acid, linoleic acid and linolenic acid, and further these penta compounds Erythritol ethylene oxide and / or propylene oxide 1
.About.5 adducts and the like.

The ester compound of each of pentaerythritol with a carboxylic acid having a hydrocarbon group R having a carbon number of less than 10 has a high volatility and volatilizes 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, so that they easily appear on the resin surface and cause mold stains and molded product stains. In addition, f and g in [Chemical Formula 3] or [Chemical Formula 4] are 5
And those in which n in [Chemical Formula 4] exceeds 3,
Since it has a low compatibility with the methyl methacrylate polymer, it tends 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, 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 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 pentaerythritols 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 appears. . Within the range of this ratio, it is selected according to the composition, molecular weight, fluidity, etc. of the methyl methacrylate polymer used.

The total amount of the pentaerythritols and the higher fatty acid is 0.02 to 0.5 part by weight, preferably 0.05, based on 100 parts by weight of the methyl methacrylate polymer.
~ 0.2 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 prepare the composition by incorporating the pentaerythritols 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 pentaerythritols and 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, an emulsion polymerization method, There is a known method such as a solution polymerization method.

The methacrylic resin composition of the present invention includes well-known antioxidants such as 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.

[0022]

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.

[0023]

The present invention will be further described with reference to the following examples. The evaluation methods used in the examples are as follows. -Releasability: Injection molding machine with capacity of 13 ounces (M-140SJ type, manufactured by each machine) with 25 mm x 76.5 mm x 3.
Attach a 2mm 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 dipentaerythritol tripalmitate, and stearic acid of 0. After mixing 025 parts with a Henschel type mixer, pelletization was performed 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 dipentaerythritol tripalmitate and stearic acid added were changed as shown in Table 1. The results obtained are shown in Table 1.

Examples 6 to 8 The procedure of Example 2 was repeated except that pentaerythritol was changed as shown in Table 1. The results obtained are shown in Table 1.

Example 9 Example 9 was repeated except that palmitic acid was used instead of stearic acid. The results obtained are shown in Table 1.

[0028]

[Table 1] Note: dipentaerythritol tripalmitate means dipentaerythritol hexabehenate, monopentaerythritol means tripentaerythritol.

Claims (1)

[Claims] 1. To 100 parts by weight of a methyl methacrylate polymer, at least one selected from pentaerythritols represented by the following [Chemical formula 1] or [Chemical formula 2] and having 10 to 22 carbon atoms. Weight ratio of higher fatty acid 10/90 to 90 /
10, a methacrylic resin composition containing 0.02 to 0.5 part by weight. [Chemical 1] In the formula, X ¹ , X ² , X ³ and X ⁴ are ones shown in the following [External 1]. [Outer 1] [Chemical 2] In the formula, X ⁵ , X ⁶ , X ⁷ , X ⁸ , X ⁹ , X ¹⁰ , X ¹¹ and X
¹² is the same as the above X ¹ , X ² , X ³ and X ⁴ , and n is 0 to
It is 3.