JPH04335051A - Transparent heat-resistant resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in mold release in high- temperature molding, an appearance of a molding, etc., by mixing a specified copolymer with a specified glycerol/higher fatty acid monoester in a specified ratio. CONSTITUTION:The title composition comprises a copolymer containing at least 3wt.% six-membered acid anhydride units of formula I and having a reduced viscosity of 0.01-1.0l/g as measured in acetone at 25 deg.C (e.g. a copolymer prepared by polymerizing methyl methacrylate with styrene and methacrylic acid) and 300-7000ppm of a glycerol/higher fatty acid monoester of formula II (wherein R is a mixture of 10-30C alkyl groups having a content of 18C alkyl groups of 80-99%).

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a copolymer containing a 6-membered cyclic acid anhydride unit and a glycerin higher fatty acid monoester of a specific amount and composition, which has excellent mold releasability during molding. The present invention also relates to a transparent heat-resistant resin composition that gives a molded article a good appearance.

0002

[Prior Art] Conventionally, resins with excellent transparency such as polymethyl methacrylate and polystyrene have been widely used in, for example, vehicle parts, lighting parts, optical parts, and food packaging supplies. In applications, there is a strong demand for advanced performance, especially excellent heat resistance.

There are several methods for improving the heat resistance of these methyl methacrylate-based polymers and styrene-based polymers, but among them, the method of incorporating a 6-membered cyclic acid anhydride unit has excellent heat resistance. In addition, it has many excellent properties such as mechanical strength and transparency, making it particularly useful. The uses of such transparent resins with excellent heat resistance are as mentioned above, but in recent years, in particular,
There are strong demands for larger sizes, more complex designs, improved mold transferability, etc. In order to meet these demands, molds are becoming larger, more complex, ultra-mirrored, and finer. However, when molding is actually performed using such molds, the quality of the molded product It becomes difficult to release the mold from the mold, resulting in many molding defects.
There has been an increasing demand for transparent heat-resistant resins with excellent mold release properties.

[0004] Conventionally, methyl methacrylate polymers have
Liquid paraffin, wax, higher fatty acid esters, higher fatty alcohols, etc. were used as mold release agents.
In either case, the mold releasability was not at a satisfactory level. Also,
A method using stearic acid, higher fatty acids such as stearic acid metal salts, and their metal salts (Japanese Patent Application Laid-Open No. 61-7375)
4, JP-A-2-115255) has a high effect of improving mold releasability, but severe mold corrosion is a problem, and in the case of heat-resistant resins that require high-temperature molding, such as the copolymer of the present invention. This problem becomes even bigger. As a method for improving mold releasability without mold corrosion, a method of adding glycerin higher fatty acid monoester and saturated higher aliphatic alcohol has been disclosed (JP-A-1-294763, JP-A-2-187).
447). However, even with this method, the mold releasability is still insufficient, and furthermore, when molded at high temperatures, silver streaks are likely to occur on the surface of the molded product.

[0005]

[Problems to be Solved by the Invention] The present inventors have made intensive studies to overcome the drawbacks of the conventional formulations that impart mold releasability as described above, and as a result, the mold releasability during high-temperature molding has been significantly improved. We have discovered a transparent heat-resistant resin composition that is able to reduce cloudiness on the surface of molded products, and maintains the characteristics originally possessed by transparent heat-resistant resins, such as heat resistance, mechanical strength, and transparency. This led to the present invention.

[0006]

[Means for Solving the Problems] That is, the present invention solves the problems by the following formula (
A copolymer containing at least 3% by weight of 6-membered cyclic acid anhydride units represented by 1), and containing 2% by weight in acetone.
Reduced viscosity at 5℃ is 0.01 to 1.0 deciliter/
g and a copolymer represented by the following general formula (2)

000
7]

[C3]

Glycerin higher fatty acid monoester 3
00 to 7000 ppm.

[0009]

[C4]

R: Alkyl having 10 to 30 carbon atoms, and the ratio of alkyl having 18 carbon atoms is 80 to 99.
The glycerin higher fatty acid monoester, which is a component of the composition of the present invention, is represented by the following general formula (2), where the ratio of alkyl having 18 carbon atoms in R is 80 to 99%. This is very important. If this ratio is less than 80%, not only will the mold releasability be poor, but the surface of the mold will tend to become cloudy, resulting in the appearance of the molded product.

[0011]

[C5]

R: alkyl having 10 to 30 carbon atoms, and the ratio of alkyl having 18 carbon atoms is 80 to 99
There is a problem that cloudiness is transferred to the alkyl surface, which is %. When this ratio exceeds 99%, clouding is also likely to occur on the mold surface. Moreover, glycerin higher fatty acid monoesters with this ratio exceeding 99% are not produced industrially. Even if this product were to be manufactured, it would be very expensive and would have a significant cost disadvantage as an additive for general-purpose resins. The preferred ratio is 85-99%.

[0013] The ratio of alkyl having 18 carbon atoms is from 80 to
Although it is not clear why 99% of cases exhibit such a remarkable effect of improving mold releasability, suppressing clouding on the mold surface, and suppressing clouding of molded products, it is due to changes in the number of carbon atoms in the alkyl. It is presumed that one reason for this is that the polarity of the glycerin higher fatty acid monoester changes, resulting in a change in compatibility with the copolymer.

The content is in the range of 300 to 7000 ppm, preferably 400 to 6000 ppm, and more preferably 500 to 5000 ppm. If this content is less than 300 ppm, the effect of improving mold releasability will be significantly reduced, and if it exceeds 7,000 ppm, mold releasability will be good but heat resistance will decrease, and furthermore, due to bleeding of additives. Significant mold contamination.

[0015] Generally, industrially produced glycerin higher fatty acid monoesters contain several percent of diesters and triesters as impurities, but such amounts may impair the characteristics of the composition of the present invention. There isn't. The copolymer containing a 6-membered cyclic acid anhydride unit used in the present invention is a copolymer containing at least one type of ethylenically unsaturated monomer unit. Ethylenically unsaturated monomer units include methyl methacrylate, methyl acrylate,
In addition to esters of acrylic acid and methacrylic acid such as ethyl acrylate, butyl acrylate, cyclohexyl methacrylate, and t-butylcyclohexyl methacrylate, aromatic vinyls such as styrene and α-methylstyrene, methacrylic acid, acrylic acid, Usually radical polymerizable monomers such as vinyl chloride, vinyl acetate, acrylonitrile, etc. can be used. Among these ethylenically unsaturated monomer units, methyl methacrylate, styrene, and α-methylstyrene are particularly preferred. The methyl methacrylate unit improves the mechanical strength of the copolymer containing the 6-membered cyclic acid anhydride unit,
Improves properties such as oil resistance. In addition, the styrene unit is
Improve its mechanical strength, water resistance, etc. Furthermore, the α-methylstyrene unit improves its water resistance as well as its heat resistance.

The amount of 6-membered cyclic acid anhydride units in the copolymer is:
At least 3% by weight or more is required. Preferably it is 5% by weight or more. If it is less than 3% by weight, the effect of improving heat resistance will be insufficient. Among the above copolymers, in particular, 3 to 85% by weight of 6-membered cyclic acid anhydride units, 13 to 95% by weight of methyl methacrylate units, and 1 to 70% by weight of aromatic vinyl units.
It is preferable to use a copolymer consisting of , and 1 to 20% by weight of methacrylic acid units. In this copolymer,
The upper limit of the amount of 6-membered cyclic acid anhydride units is 85% by weight, preferably 75% by weight, and more preferably 50% by weight. 8
If it exceeds 5% by weight, water resistance will be extremely reduced. The amount of methyl methacrylate units is from 13 to 95% by weight, preferably from 15 to 88% by weight. If it is less than 13% by weight, the mechanical strength will decrease, and if it exceeds 95% by weight, the amount of 6-membered cyclic acid anhydride units introduced will not be sufficient and the heat resistance will decrease. The amount of aromatic vinyl units is 1 to 70% by weight
, preferably 5 to 50% by weight. The aromatic vinyl unit compensates for the low water resistance of the 6-membered cyclic acid anhydride unit and at the same time contributes to improving mechanical strength, but if it is less than 1% by weight, these effects are not sufficient, and 70 If it exceeds % by weight, the amount of 6-membered cyclic acid anhydride introduced will not be sufficient and the heat resistance will deteriorate.

Methacrylic acid is a necessary component for forming a 6-membered cyclic acid anhydride unit. A copolymer containing this component is heat-treated to form a 6-membered cyclic acid anhydride unit through dehydration or dealcoholization, but at this time, the methacrylic acid unit is not completely consumed, and the methacrylic acid unit remains in the copolymer. remains. The amount of methacrylic acid units in the copolymer is from 1 to
20% by weight, preferably 2-10% by weight. If it exceeds 20% by weight, the remaining methacrylic acid units will cause dehydration or dealcoholization reactions during molding, causing foaming of the molded product, which is undesirable.

Furthermore, the copolymer used in the present invention has a reduced viscosity of 0.01 to 1.0 dl/g, preferably 0.05 to 0.5 dl/g in acetone at 25°C. . If the reduced viscosity is less than 0.01 deciliter/g, the mechanical strength will be insufficient, and if it exceeds 1.0 deciliter/g, the melt fluidity during heating will decrease and moldability will decrease. .

Further, in the copolymer used in the present invention, the amount of volatile matter is 1.5% by weight or less, preferably 1.0% by weight.
% by weight or less. If the amount of volatile matter exceeds 1.5% by weight, it is not preferable because heat resistance may deteriorate and silver streaks may occur during molding. The copolymer used in the present invention is usually prepared by copolymerizing an ethylenically unsaturated monomer with methacrylic acid, and then
It is produced by heat-treating this copolymer to form a 6-membered cyclic acid anhydride unit. As the copolymerization method, all conventional radical polymerization methods can be used, and suspension polymerization, bulk polymerization, and solution polymerization are particularly preferred. Among these, continuous bulk polymerization and continuous solution polymerization are particularly preferred. As a means for forming the 6-membered cyclic acid anhydride unit, an extruder with a devolatilization device, a retention devolatilization device, etc. can be used.

Methods for adding the glycerin higher fatty acid monoester to the composition of the present invention include a method in which it is dissolved in a monomer and polymerized as a homogeneous solution, and a method in which it is subsequently added to a copolymer in a molten state, beads, or pellets and kneaded. There is a way to do it. In order to effectively express the effects of glycerin higher fatty acid monoester, a post-addition method is desirable. Although the cause of this is not clear, it is presumed that changes in the dispersion state of the glycerin higher fatty acid monoester are involved.

[0021] Furthermore, known additives such as lubricants, antioxidants, antistatic agents, ultraviolet absorbers, etc. can be added to the composition of the present invention to the extent that its properties are not impaired. Furthermore, other resins such as methyl methacrylate polymers and MBS can also be mixed into the composition of the present invention within a range that does not impair its properties.

[0022]

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples in any way. In addition, various analyzes and physical property evaluations of the copolymers and compositions were performed by the following methods. (1) Dissolve 0.150 g of the reduced viscosity copolymer in acetone to make a 50 ml solution. The reduced viscosity of this acetone solution is 25°C.
It was measured using a Cannon Fenske viscosity tube #50.

(2) Vicat Softening Temperature Measured according to ASTM D-1525. (3) Quantification of glycerin higher fatty acid monoester After dissolving 1.00 g of the resin composition in 10 ml of methylene chloride containing an internal standard substance, 100 microliters of BSA (bistrimethylsilylacetamide) was added,
The reaction mixture was reacted at 35±5°C for 24 hours and analyzed by GC.

(4) Evaluation of mold releasability A 4-plate mold as shown in Figure 1 was attached to a 3oz injection molding machine, and the conditions were as follows: mold temperature 50°C, and injection pressure 920Kg/cm2. When molding was carried out below, those in which cracks, chips, or cracks occurred in the four-stage plate molded product were considered to be defective products, and the percentage of defective products among all molded products was defined as the defective incidence rate.

The number of moldings is 3 to stabilize the injection conditions.
After 0 shot molding, 30 shots were used as samples for evaluation. In addition, during molding, the pellets are dried,
It was used at a moisture content of 0.06% or less. (5) Evaluation of mold surface cloudiness During sample molding in (4), cloudiness on the mold surface was visually observed and evaluated based on the number of shots in which clear cloudiness occurred.

[Production of 6-membered cyclic acid anhydride-containing copolymer] [
Production of copolymer A] Methyl methacrylate 38.4% by weight
, styrene 5.4% by weight, methacrylic acid 16.2% by weight
, t-butanol 40.0% by weight, 1,1-di-ter
A mixed solution consisting of 500 ppm of t-butylperoxy-3,3,5-trimethylcyclohexanone and 3000 ppm of n-octyl mercaptan was prepared, and this mixed solution was continuously added at a rate of 0.5 liters/hr to a content of 2. The polymerization was carried out at 125° C. by feeding the mixture into a small jacketed complete mixing reactor. Furthermore, the polymerization liquid was continuously supplied to a high-temperature devolatilization device set at 260°C to remove unreacted substances.
Then, a 6-membered cyclic acid anhydride unit was formed.

The composition of this copolymer was analyzed by neutralization titration, an infrared spectrophotometer, and a nuclear magnetic resonance analyzer, and the results showed that it contained 62% by weight of methyl methacrylate units, 10% by weight of styrene units, and 6-membered rings. 25% by weight of acid anhydride units, and
The content of methacrylic acid units was 3% by weight. Further, the reduced viscosity of this copolymer was 0.08 deciliter/g.

[Production of copolymer B] The composition of the mixed solution is as follows:
Methyl methacrylate 72.9% by weight, α-methylstyrene 13.5% by weight, methacrylic acid 3.6% by weight, ethylbenzene 10.0% by weight, 1,1-di-tert-butylperoxy-3,3, 5-trimethylcyclohexanone 300 ppm and n-octyl mercaptan 10
The process was carried out in the same manner as the production of copolymer A except that the amount was 00 ppm.

The composition of the obtained copolymer was as follows: 85% by weight of methyl methacrylate units, 8% by weight of α-methylstyrene units, 4% by weight of 6-membered cyclic acid anhydride units, and 3% by weight of methacrylic acid units.
In weight percent, the reduced viscosity was 0.15 deciliter/g. [Production of Copolymer C] The composition of the mixed solution was 21.6% by weight of methyl methacrylate, 23.2% by weight of α-methylstyrene, 35.2% by weight of methacrylic acid, and 2% by weight of t-butanol.
0.0% by weight, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexanone 500p
pm, and n-octyl mercaptan 1000 ppm
The process was carried out in the same manner as in the production of copolymer A except for the following.

The composition of the obtained copolymer was 30% by weight of methyl methacrylate units, 18% by weight of α-methylstyrene units, 44% by weight of 6-membered cyclic acid anhydride units, and 8% by weight of methacrylic acid units. The viscosity was 0.05 deciliter/g.

[0031]

Example 1 Pellets of copolymer A were mixed with 1500 ppm of glycerin higher fatty acid monoester in which the ratio of alkyl having 18 carbon atoms in R was 87% and pelletized. Using the obtained pellets, analysis and physical property evaluation were performed using the method described above. The results are shown in Table 1.

[0032]

[Examples 2 to 5, Comparative Examples 1 to 5] The same procedure as in Example 1 was carried out except that the composition and blending amount of the glycerin higher fatty acid monoester were changed. The results are shown in Table 1.

[0033]

Example 6 The same procedure as in Example 1 was carried out except that the copolymer used was changed to copolymer B. The results are shown in Table 1.

[0034]

[Example 7] The same procedure as in Example 1 was carried out except that the copolymer used was changed to copolymer C. The results are shown in Table 1.

[0035]

[Example 8] Except that the copolymer used was changed to a mixture of 30 parts by weight of pellets of copolymer C and 70 parts by weight of pellets of methacrylic polymer (manufactured by Asahi Kasei Corporation, trade name Delpet 80N). was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0036]

[Comparative Example 6] The copolymer used was changed to copolymer B,
The same procedure as in Example 1 was carried out except that the composition of the glycerin higher fatty acid monoester was changed. The results are shown in Table 1.

[0037]

[Comparative Example 7] The copolymer used was changed to copolymer C,
The same procedure as in Example 1 was carried out except that the composition of the glycerin higher fatty acid monoester was changed. The results are shown in Table 1.

[0038]

[Table 1]

[0039]

Effects of the Invention According to the present invention, the mold releasability during high-temperature molding is significantly improved, the appearance of the molded product is good, and the copolymer has the inherent heat resistance and mechanical strength. , a transparent heat-resistant resin composition that maintains characteristics such as transparency can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the shape of an injection molded product and evaluation of mold releasability.

Claims (1)

[Claims] Claim 1: A copolymer containing at least 3% by weight of 6-membered cyclic acid anhydride units represented by the following formula (1), and having a reduced viscosity of 0.01 at 25°C in acetone.
~1.0 deciliter/g of a copolymer and a glycerin higher fatty acid monoester represented by the following general formula (2): 300 to 7,000
A transparent heat-resistant resin composition consisting of ppm. [Formula 2] R: Alkyl having 10 to 30 carbon atoms, and the ratio of alkyl having 18 carbon atoms is 80 to 99%