JPH0641385A - Methacrylic resin composition - Google Patents

Abstract

PURPOSE:To provide the methacrylic resin composition, having excellent mold release properties in molding processing with a metallic mold and excellent in transparency and weather resistance by adding specific methylolpropanes and a specified alcohol together to a methyl methacrylate-based polymer. CONSTITUTION:The composition is obtained by blending (A) a methyl methacrylate-based polymer with (B) trimethylolpropanes selected from formulas I and II [each of X<1>, to X<8> is H, formula III (R is 10-22C hydrocarbon), etc.] and (C) a 10-22C saturated aliphatic alcohol so as to provide (10/90) to (90/10) weight ratio of the components (B)/(C) and 0.02-0.5 pt.wt. total amount of the components (B) and (C) based on 100 pts.wt. component (A). For example, monotrimethylolpropane is cited as the component (B) and, e.g. lauryl alcohol can be used as the component (C).

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 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, Japanese Patent Laid-Open No. 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]

The present invention comprises 100 parts by weight of a methyl methacrylate polymer and at least one selected from trimethylolpropanes represented by the following [Chemical formula 3] or [Chemical formula 4]. A saturated aliphatic alcohol having 10 to 22 carbon atoms in a weight ratio of 10/90 to 90/10 and 0.02 to
The present invention relates to a methacrylic resin composition containing 0.5 part by weight.

[0007]

[Chemical 3]

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

[0009]

[Outside 2]

[0010]

[Chemical 4]

Where X ⁴ , X ⁵ , X ⁶ , X ⁷ and X ⁸ are
Same as the above X ¹ , X ² , and X ³ , 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 trimethylolpropanes represented by the above [Chemical formula 3] or [Chemical formula 4] of the present invention include monotrimethylolpropane, ditrimethylolpropane, tritrimethylolpropane, tetratrimethylolpropane,
And pentatrimethylolpropane, and trimethylolpropane and carboxylic acids 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 ester compounds thereof, and addition products of 1 to 5 ethylene oxide and / or propylene oxide adducts of trimethylolpropane.

If the hydrocarbon group R of each ester compound with carboxylic acid of trimethylolpropane has a carbon number of less than 10, it 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. Further, those in which f and g in [Chemical Formula 3] or [Chemical Formula 4] exceed 5 and those in which n in [Chemical Formula 4] exceeds 3 have low compatibility with a methyl methacrylate polymer, It is not preferable because it easily appears on the resin surface and causes stains on the mold and molded articles.

Examples of the saturated aliphatic alcohol having 10 to 22 carbon atoms in the present invention include lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, isostearyl alcohol and behenyl alcohol.

When the saturated aliphatic alcohol 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, if the carbon number exceeds 22,
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.

In the present invention, the trimethylolpropanes and the saturated aliphatic alcohol are 10/90 to 9
When used in a ratio of 0/10, 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 and the like of the methyl methacrylate polymer used.

The total amount of the trimethylolpropanes and the saturated aliphatic alcohol is 0.02 to 0.5 part by weight, preferably 0.05 to 0.2, based on 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 mold release agent adheres to the mold surface, and the mold becomes dirty.
It is not preferable because it becomes a contaminated molded product.

A well-known method can be used to prepare the composition by incorporating the trimethylolpropanes and the saturated aliphatic alcohol 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 trimethylolpropanes and the saturated aliphatic alcohol 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 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 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 a granular methacrylic resin obtained by suspension polymerization (Sumipex B LO, manufactured by Sumitomo Chemical Co., Ltd.) and ditrimethylolpropane / propylene oxide 3 adduct.
025 parts and stearyl alcohol 0.025 parts,
After mixing 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 The procedure of Example 1 was repeated, except that the addition amounts of ditrimethylolpropane / propylene oxide 3 adduct and stearyl alcohol were changed as shown in Table 1. The results obtained are shown in Table 1.

Example 6 Except that ditrimethylolpropane-propylene oxide 3 adduct was replaced by ditrimethylolpropane,
The same procedure as in Example 2 was performed. The results obtained are shown in Table 1.

Example 7 Example 2 was repeated except that cetyl alcohol was used instead of stearyl alcohol. The results obtained are shown in Table 1.

[0028]

[Table 1] Note: Ditrimethylolpropane propylene oxide 3 adduct is ditrimethylolpropane.

Claims (1)

[Claims] 1. To 100 parts by weight of a methyl methacrylate polymer, at least one selected from trimethylolpropanes represented by the following [Chemical formula 1] or [Chemical formula 2] and 10 carbon atoms.
~ 22 saturated aliphatic alcohol in a weight ratio of 10 / 90-9
A methacrylic resin composition, which is 0/10 and contains 0.02 to 0.5 part by weight. [Chemical 1] In the formula, X ¹ , X ² , and X ³ are ones shown in [External 1] below. [Outer 1] [Chemical 2] In the formula, X ⁴ , X ⁵ , X ⁶ , X ⁷ and X ⁸ are the above-mentioned X ¹ , X
^The same as ² and X ³ , n is 0 to 3.