JPH06240093A - Methacrylate resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition improved in mold release, transparency and weather resistance by mixing a methyl meth-acrylate polymer with a specified pentaerythritol and a monoglyceride of a higher fatty acid. CONSTITUTION:100 pts.wt. methyl methacrylate polymer (A) prepared by polymerizing methyl methacrylate or copolymerizing methyl methacrylate with at most 20wt.% another monomer is kneaded together with at least one pentaerythritol (B) selected from compounds of formulas I and II [wherein X<1> to X<12> are each H or a group of formula III, IV or V (wherein R is a 10-22 C hydrocarbon group; and (f) and (g) are each 1-5); and (n) is 0-3] and a monoglyceride (c) of a 10-22 C fatty acid in amounts to give a component B to component C weight ratio of 10/90 to 90/10 and a total of components B and C of 0.02-0.5, or components B and C are added to a monomer or syrup based on methyl methacrylate, the resulting mixture is polymerized by e.g. bulk polymerization, and the resulting product is optionally mixed with an antioxidant, a light stabilizer, a reinforcing fiber, etc., to obtain the objective composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. 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
The publication discloses a resin composition in which 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 are added 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 mold release agents and exhibits an excellent mold release effect with a smaller amount.

[0006]

The present invention provides at least one selected from pentaerythritols represented by the following [Chemical formula 3] or [Chemical formula 4] with respect to 100 parts by weight of a methyl methacrylate polymer. And a glycerol monoester of a higher fatty acid having 10 to 22 carbon atoms in a weight ratio of 10/90 to 90/1
0, and relates to a methacrylic resin composition containing 0.02 to 0.5 part 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 a homopolymer of methyl methacrylate, or methyl methacrylate and 20% by weight or less of acrylic acid ester or methacrylic acid ester, acrylic acid, methacrylic acid, styrene, acrylonitrile. Alternatively, it refers to a copolymer with a diene rubber, glutaric anhydride, glutarimide, or the like. As the acrylic ester, methyl acrylate, ethyl acrylate, butyl acrylate, etc.
Examples of the methacrylic acid ester include ethyl methacrylate, butyl methacrylate and cyclohexyl methacrylate.

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,
Due to its low compatibility with methyl methacrylate polymers,
It is not preferable because it easily appears on the resin surface and causes stains on the mold and molded articles.

Examples of the glycerin monoester of higher fatty acid having 10 to 22 carbon atoms of the present invention include lauric acid monoglyceride, palmitic acid monoglyceride, stearic acid monoglyceride, oleic acid monoglyceride, behenic acid monoglyceride and the like.

The higher fatty acid glycerin monoester of higher fatty acid having a carbon number of less than 10 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, the pentaerythritols and the glycerin monoester of the higher fatty acid are 1
0/90 to 90/10, preferably 25/75 to 75
When used at a ratio of / 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 glycerin monoester of the higher fatty acid is 0.02 to 0.5 part by weight, preferably 0.05 to 0.2, per 100 parts by weight of the methyl methacrylate polymer. 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, when the addition amount exceeds 0.5 parts by weight, the molded product is colored, and the excess release agent adheres to the mold surface,
This is not preferable because the mold becomes a dirty and contaminated molded product.

A well-known method can be used to prepare a composition by incorporating the pentaerythritols and the glycerin monoester of 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 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 resulting mixture is subjected to a bulk polymerization method, a suspension polymerization method or an emulsification method. There are known methods such as a polymerization method and a solution polymerization method.

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 photostabilizers. It is also possible to add weathering agents such as agents, flame retardants, colorants, pigments, etc., and depending on the purpose, reinforcing fibers such as glass fibers, inorganic fillers, etc. may also be added.

[0022]

The methacrylic resin composition of the present invention is
Compared with the conventional methacrylic resin, it has excellent mold 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 a molded product having a complicated shape such as an automobile part such as a meter cover, an optical part such as a video disk and a lens, a lighting part, and an OA equipment part 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 monoglyceride stearate. 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 and Comparative Examples 1 to 4 Example 1 was repeated except that the amounts of dipentaerythritol tripalmitate and monoglyceride stearate 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 The same procedure as in Example 2 was carried out except that palmitic acid monoglyceride was used instead of stearic acid monoglyceride. The results obtained are shown in Table 1.

[0028]

[Table 1] Note: dipentaerythritol tripalmitate dipentaerythritol hexabehenate monopentaerythritol tripentaerythritol stearic acid monoglyceride palmitic acid monoglyceride

Claims (1)

[Claims] 1. At least one selected from the pentaerythritols represented by the following [Chemical formula 1] or [Chemical formula 2] and a higher carbon number of 10 to 22 per 100 parts by weight of a methyl methacrylate polymer. A methacrylic resin composition comprising a glycerin monoester of a fatty acid in a weight ratio of 10/90 to 90/10 and 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.