JPH0215583B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a methyl methacrylate-based impact-resistant resin composition. In more detail,
The present invention is a methyl methacrylate-based impact resistant material that has excellent transparency, heat resistance, and impact resistance, and is suitably used for automobile parts, industrial parts, home appliance parts, etc., by mixing a heat-resistant copolymer and a graft rubber. This invention relates to a resin composition. (Prior Art) In recent years, the demand for impact-resistant resins with excellent transparency and heat resistance has become particularly strong in applications such as light electrical parts and automobile parts. Among currently commercially available resins, polycarbonate is known as a representative resin that is transparent and has excellent heat resistance and impact resistance. However, this resin is not widely used due to its high price. Recently, impact-resistant methyl methacrylate resin compositions (HI-PMMA), which maintain the transparency, oil resistance, and weather resistance of methyl methacrylate resin and add impact resistance through rubber reinforcement, have begun to be commercially available. The disadvantage is that they have poor heat resistance. Under these circumstances, the inventors of the present invention endeavored to develop a resin with excellent transparency, heat resistance, impact resistance, and oil resistance. It has been discovered that the objective can be achieved by combining the above with a copolymer containing the following. However, the heat resistance of this copolymer has a limit, and under high temperature and high humidity conditions, the amount of moisture absorbed further increases, and the heat resistance may actually decrease. (Problems to be Solved by the Invention) Under these circumstances, the purpose of the present invention is to improve the transparency of a highly heat-resistant copolymer mainly composed of methyl methacrylate units and six-membered cyclic acid anhydride units. The aim is to further improve heat resistance while maintaining impact resistance. (Means for Solving the Problems) In order to achieve the above object, the present inventor conducted further studies and found that most of the six-membered cyclic acid anhydride units in the copolymer were converted into six-membered cyclic imide units. It has been found that by converting into units, the heat resistance of the copolymer and, therefore, the heat resistance of the composition is further improved, and furthermore, the hygroscopicity is also improved. On the other hand, they have also discovered that the ability of the grafted rubber to be well compatible with this six-membered ring imide-containing copolymer and to maintain transparency can be achieved by carefully selecting the components of the copolymer to be grafted onto the rubber. This led to the completion of the present invention. That is, the present invention comprises 20 to 95 mol% of methyl methacrylate units, the general formula (In the formula, R is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group). unit 0.1 to 50 mol%, imide unit of formula (2) 2 to 77 mol%, aromatic vinyl unit 1 to
The viscosity of a methyl ethyl ketone solution containing 70 mol% and 1 to 20 mol% of methacrylic acid units and a 10% by weight copolymer concentration at a temperature of 25°C is 3 to 20%.
50 to 98% by weight of copolymer (A) that is centipoise;
Rubber having a glass transition temperature of -30°C or less contains 30 to 95 mol% of methyl methacrylate units, 5 to 70 mol% of aromatic vinyl units, and 0.1 to 50 methacrylic acid units.
Grafted rubber (B) 2 to 50 mol % of a copolymer grafted with a copolymer which optionally also contains an acid anhydride unit of the above formula (1) and/or an imide unit of the above formula (2)
% by weight, and is transparent and has excellent heat resistance and impact resistance. The resin composition of the present invention is composed of a copolymer (A) that is colorless and transparent and has excellent heat resistance, and a graft rubber (B) that has substantially the same refractive index as the copolymer (A), and has impact resistance, transparency, It is characterized by having heat resistance. The copolymer (A) constituting the resin composition of the present invention has excellent heat resistance and has a high heat distortion temperature and a high thermal decomposition temperature, and is mainly composed of methyl methacrylate units, six-membered cyclic acid anhydrides, and six-membered cyclic imide units. It also contains necessary amounts of aromatic vinyl units and methacrylic acid units. The methyl methacrylate unit that makes up this copolymer (A) has the effect of exhibiting oil resistance and strength.
95 mol% is required, but preferably 25 to 90 mol%. If it is less than 20 mol%, the strength and oil resistance of the copolymer (A) will be insufficient, and the resin composition will also have insufficient impact resistance, which is not preferable. The six-membered ring structural unit constituting the copolymer (A) consists of the following formulas (1) and (2). (In the formula, R is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group.)
All of them play the role of increasing heat resistance, and their content is 3 to 78 mol%, preferably 5 to 50 mol%. If it is less than 3 mol %, there is no effect of improving heat resistance, and if it exceeds 78 mol %, the melt flowability of the resin composition will decrease, which is not preferable because molding processability will decrease. This six-membered ring structural unit is a six-membered ring acid anhydride unit.
0.1 to 50 mol% and 2 to 77 mol% of six-membered ring imide units
Preferably, the main component is six-membered cyclic imide units, and 0.1 to 10 six-membered cyclic acid anhydride units.
mol%, and the six-membered ring imide unit is 4 to 50 mol%
It is. The six-membered ring imide unit is excellent in terms of heat resistance and water resistance, but it also prevents a decrease in melt fluidity and has good compatibility with the graft rubber component, which is the other component that makes up the resin composition. A six-membered cyclic acid anhydride unit is required to maintain the structure. The aromatic vinyl unit constituting the copolymer (A) has the function of maintaining high melt fluidity and suppressing hygroscopicity, and is 1 to 70 mol%, preferably 5 to 50 mol%. If it is less than 1 mol %, the melt fluidity will be greatly reduced and the hygroscopicity will also be large, which is not preferable. On the other hand, if it exceeds 70 mol%, mechanical strength decreases, which is not preferable. This copolymer (A)
The aromatic vinyls that make up include styrene, α
Examples include -methylstyrene, p-methylstyrene, chlorostyrene, p-tert-butylstyrene, etc., but styrene alone or a combination of styrene and α-methylstyrene are preferred. The methacrylic acid unit constituting the copolymer (A) plays the role of improving heat resistance together with the six-membered ring structural unit, and is in the range of 1 to 20 mol%, preferably 1 to 15 mol%. be. If it is less than 1 mol %, it will not play a role in improving heat resistance, and if it exceeds 20 mol %, thermal decomposition will become large, and if the resin composition is molded at 260° C. or higher, gas will be generated, which is not preferable. This copolymer (A) requires an appropriate molecular weight. One way to express this molecular weight is concentration
Using the viscosity of a 10% by weight methyl ethyl ketone solution at a temperature of 25 DEG C., it is not preferred for the composition unless it is 3 to 20 centipoise, preferably 3 to 10 centipoise. If it is less than 3 centipoise, the impact resistance of the composition will decrease, which is undesirable, while if it exceeds 20 centipoise, the melt flowability of the composition will decrease, resulting in poor moldability, which is undesirable. The six-membered ring structural unit of copolymer (A) is obtained by converting most of the six-membered cyclic acid anhydride units into imide units; Ammonia, aliphatic primary amines, aromatic amines, etc. are used for modification. As ammonia, liquid ammonia, ammonia gas, ammonia water can be used, and as aliphatic primary amines, for example, methylamine, ethylamine, n-propylamine, iso-propylamine, tert-butylamine, pentylamine,
Examples include hexylamine, cyclohexylamine, and allylamine, which can also be used as an aqueous solution. Examples of aromatic amines include aniline, o-toluidine, p-toluidine, o-chloroaniline, p-chloroaniline, 2,4,6-trichloroaniline, α-naphthylamine, β-naphthylamine, and the like. Benzylamine, DL-, D- or L-
α-phenethylamine, β-phenethylamine, etc. can also be used. Furthermore, polyamines such as 2-diethylaminoethylamine and hydroxylamines such as isopropanolamine can also be used. Next, various methods can be used to modify the six-membered cyclic acid anhydride unit into the six-membered cyclic imide unit. For example, a copolymer containing a six-membered cyclic acid anhydride unit is charged as a reaction precursor in an autoclave, then aqueous ammonia is injected in a solution state to react, and the imide is further treated at a temperature of 250°C for 2 hours. Alternatively, the precursor copolymer is continuously melted using an extruder, and then aqueous ammonia, cyclohexylamine, aniline, etc. are continuously injected, and then cyclized to imide in a vacuum chamber. etc. are used. In the resin composition of the present invention, component (B) is a graft rubber. The rubber constituting this graft rubber (B) must have a glass transition temperature of -30°C or lower. If a rubber with a temperature exceeding -30°C is used, the impact resistance of the composition will be unsatisfactory. A typical example of this rubber is polybutadiene or a butadiene copolymer containing 60% by weight or more of butadiene units. In the case of a copolymer, the component other than butadiene is an aromatic vinyl, mainly styrene, but vinyl cyanide such as acrylonitrile may also be used. The rubber content in this graft rubber (B) ranges from 40 to 90% by weight. If it is less than 40% by weight, the grafting rate is too high, resulting in a decrease in impact resistance.
When it exceeds 90% by weight, the grafting rate decreases, resulting in a composition with extremely poor gloss, which impairs the appearance of the molded product. From these results, the amount of the graft copolymer in the graft rubber (B) is 60 to 10% by weight. Next, the graft copolymer constituting the graft rubber (B) is located at the interface between the rubber and the copolymer (A), and improves the adhesion between the two to make the impact resistance effect of the graft rubber effective. It has the effect of Therefore, this graft copolymer must be compatible with copolymer (A), so basically it is a copolymer.
Although it is desirable that the composition be the same as (A), as a result of various studies, it was found that it does not have to be exactly the same. However, the components of the graft copolymer require a methyl methacrylate unit, an aromatic vinyl unit, and a methacrylic acid unit, and if a part of the methacrylic acid unit is converted into a six-membered cyclic acid anhydride unit, , more preferred. It is more preferable to convert this six-membered cyclic acid anhydride unit into a six-membered cyclic imide unit by the same method as in the case of copolymer (A). In this case, the methyl methacrylate unit is 30 to 95 mol%, preferably 50 to 95 mol%, and the aromatic vinyl unit is 5 to 95 mol%.
Unless the content of methacrylic acid units is 70 mol%, preferably 5 to 50 mol%, and 0.1 to 50 mol%, this graft copolymer will not be well compatible with copolymer (A).
In this case, six-membered cyclic acid anhydride units and further six-membered cyclic imide units may be formed within the range of 0.1 to 50 mol % of methacrylic acid units. Regarding the copolymer (A), first, a terpolymer of methyl methacrylate-aromatic vinyl-methacrylic acid is obtained by radical copolymerization. In this case, the polymerization method may be bulk polymerization, solution polymerization, or suspension polymerization. This ternary copolymer is then treated at high temperature and reduced pressure to generate six-membered cyclic acid anhydride units, resulting in a quaternary system of methyl methacrylate-aromatic vinyl-methacrylic acid-six-membered cyclic acid anhydride, and further , ammonia or various primary amines to modify a part or most of the six-membered cyclic acid anhydride into a six-membered cyclic imide. Graft rubber (B) is obtained by radical polymerization of methyl methacrylate, aromatic vinyl, and methacrylic acid and/or t-butyl methacrylate in the presence of rubber.
Although either suspension two-stage polymerization or emulsion polymerization may be used, emulsion polymerization is more commonly used.
In this case, the copolymer grafted onto the rubber initially consists of methyl methacrylate units - aromatic vinyl units -
This graft copolymer is made of methacrylic acid units and/or t-butyl methacrylate units.
When treated at temperatures higher than 0.degree. C., t-butyl methacrylate units generate isobutylene and convert into methacrylic acid units. In this manner, a copolymer consisting of methyl methacrylate units, aromatic vinyl units, and methacrylic acid units is grafted onto the rubber to obtain a grafted rubber (B). However, when this graft rubber is further heated to a temperature of 200°C or higher, six-membered cyclic acid anhydride units are formed in this graft copolymer as in the case of copolymer (A), and as a result, this The components of the copolymer are methyl methacrylate units.
It may be a quaternary element consisting of an aromatic vinyl unit, a methacrylic acid unit, and a six-membered cyclic acid anhydride unit. Furthermore, when the graft rubber (B) grafted with this quaternary copolymer is treated with ammonia or various primary amines in the same manner as in the case of the copolymer (A), the A part or most of the six-membered cyclic acid anhydride can be modified into a six-membered cyclic imide. This imide modification method involves slurrying the graft rubber in an organic solvent such as methyl ethyl ketone, and heating it at 250°C for 2 hours in an autoclave with aqueous ammonia and various primary amines, or copolymer (A). The imide-modified material and the graft rubber are mixed and continuously melted using an extruder. Aqueous ammonia, cyclohexylamine, aniline, etc. are continuously injected into the extruder, and then the imide is mixed in a vacuum chamber. A method such as cyclization is used. Next, the mixing amounts of copolymer (A) and graft rubber (B) are shown. The copolymer (A) is in the range of 50 to 98% by weight, preferably 50 to 85% by weight. If it is less than 50% by weight, heat resistance will decrease, and transparency and rigidity will decrease due to an increase in the graft rubber component. If it exceeds 98% by weight, the rigidity becomes high and the impact resistance decreases, which is not preferable. Therefore, the amount of graft rubber (B) is 2 to 50% by weight, preferably 15 to 50% by weight. Blending of the copolymer (A) and the graft rubber (B) is usually carried out using an extruder, but a twin-screw extruder with a vent tube is particularly preferred. The composition thus obtained is
It can be used as it is for injection molding or extrusion molding, but if necessary, various heat stabilizers and light stabilizers such as benzotriazole type and hindered amine type may be added during blending. Anionic surfactants and anionic surfactants may also be added. Furthermore, as a lubricant, liquid paraffin, _C8 - _C22 higher fatty acids, metal salts of _C4 - _C22 higher fatty acids (calcium, magnesium, zinc, etc.), ethylene bis fatty acids ( _C16 , _C18 )
Amides, higher aliphatic alcohols such as stearyl alcohol, dibutyl or dioctyl esters of adipic acid and sebacic acid, higher fatty acids (C ₈ - C ₂₂ )
Mono-, di-, and triglycerides, hydrogenated castor oil, hydrogenated beef tallow, dimethylpolysiloxane, and the like may be added. (Effects of the Invention) According to the present invention, an impact-resistant resin composition having excellent heat resistance and transparency can be obtained. The composition is suitably used in various applications such as automobile parts, industrial parts, and home appliance parts. (Example) Next, the present invention will be explained in more detail with reference to Examples. The measurement method for each physical property is as follows. (1) Vikatsu softening temperature: ASTM-D1525 (2) Heating deformation temperature: ASTM-D648 (18.4Kg/cm ² , 1/4 inch, no annealing) (3) Izot impact strength: ASTM-D256 (1/4 inch, notched) (4) Tensile strength: ASTM-D638 (5) Tensile elongation: ASTM-D638 (6) Solution viscosity: Copolymer in methyl ethyl ketone
Solution viscosity at 25°C with a concentration of 10% by weight. A Canon Fuenske type viscosity tube (#200) was used. (7) Total light transmittance: ASTM-
Measured according to D1003. (i) Production of copolymer (A-1) A mixed solution consisting of 8 parts by weight of styrene, 12 parts by weight of methacrylic acid, 60 parts by weight of methyl methacrylate, 20 parts by weight of ethylbenzene and 0.1 part by weight of octyl mercaptan, This mixed solution was continuously fed at a rate of 0.5/hr to a jacketed complete mixing reactor having an internal volume of 2 to carry out polymerization. 1,1-di-tert-butylperoxy-3, as a polymerization initiator
3,5-trimethylcyclohexane was used and the polymerization temperature was 110°C. A polymerization reaction solution with a solid content of 42% by weight was continuously supplied to a high-temperature vacuum chamber to remove unreacted substances and produce a six-membered cyclic acid anhydride. The results of neutralization titration and compositional analysis using an infrared spectrophotometer of this copolymer were as follows: 11 mol% of styrene units, 72 mol% of methyl methacrylate units, 6 mol% of methacrylic acid units, and 6-membered cyclic acid anhydride units. It was 11 mol%. 0.5 kg of the thus obtained copolymer was charged in the form of pellets into an autoclave No. 5, and then 3.0 kg of dimethylformamide was added and stirred to dissolve the entire amount. 28% ammonia water containing was added and treated at 75°C for 2 hours. Take out the reaction solution,
After the polymer was precipitated with n-hexane and purified, the polymer was treated in a volatilization furnace at 250° C. and 10 torr for 2 hours. The final product was almost colorless and transparent, and measurements using an infrared spectrophotometer revealed a significant decrease in absorption at 1800 cm ^-1 and 1760 cm ^-1 , which is characteristic of six-membered cyclic acid anhydrides. At the same time, the formation of a six-membered ring imide was observed from a new absorption at 1700 cm ^-1 .
From the nitrogen content in elemental analysis, the six-membered ring imide unit is
The amount was 10.5 mol%. Therefore, the imidization rate is 95%
It is. The composition and properties of this copolymer are shown in Table 1. (ii) Production of copolymer (A-2) Production of copolymer (A-1) except for 20 parts by weight of styrene, 15 parts by weight of methacrylic acid, 45 parts by weight of methyl methacrylate, and 20 parts by weight of ethylbenzene. Polymerization and formation of a six-membered cyclic acid anhydride were carried out in the same manner as described above. The composition of this copolymer was 27 mol% of styrene units, 51 mol% of methyl methacrylate units, 9 mol% of methacrylic acid, and 13 mol% of six-membered cyclic acid anhydride units. Next, it was treated with ammonia in the same manner as in the production of copolymer (A-1) to produce 12 mol% of six-membered ring imide. The composition and properties of this copolymer are shown in Table 1.

[Table] (iii) Production of graft rubber (B-1) 60 parts by weight of polybutadiene rubber latex in terms of solid content and 100 parts by weight of ion-exchanged water were charged into a reactor, and heated at 70°C under stirring. Polymerization was carried out by continuously adding an aqueous solution in which a mixture of 28 parts by weight of methyl methacrylate, 8 parts by weight of styrene, 4 parts by weight of t-butyl methacrylate, and 0.1 part by weight of potassium persulfate were dissolved in 50 parts by weight of ion-exchanged water for 7 hours. After the polymerization was completed, the graft copolymer latex was salted out, dehydrated, and dried to obtain a powder. Only the acetone-insoluble portion of this powder was taken out and treated at 220° C. for 2 minutes under reduced pressure to obtain graft rubber (B-1). The refractive index of this material was 1.515. After the polybutadiene part of this graft rubber (B-1) was oxidatively decomposed by ozone oxidation method, the composition of the graft copolymer was analyzed and found to be 71 mol% of methyl methacrylate units, 20 mol% of styrene units, and 6-membered cyclic acid. The anhydride units were 4 mol % and the methacrylic acid was 5 mol %. The analytical method is the same as for copolymer (A). (iv) Production of graft rubber (B-2) Styrene-butadiene rubber (SBR) consisting of 10% by weight of styrene units and 90% by weight of butadiene units.
60 parts by weight of latex in terms of solid content and 100 parts by weight of ion-exchanged water were charged into a reactor, and at 70°C, 25 parts by weight of methyl methacrylate, 11 parts by weight of styrene,
An aqueous solution in which a mixture of 4 parts by weight of t-butyl methacrylate and 0.1 part by weight of potassium persulfate were dissolved in 50 parts by weight of ion-exchanged water was continuously added and polymerized in the same manner as in the production of graft rubber (B-1). and post-processing was performed. The graft rubber thus obtained (B
-2) has a refractive index of 1.525, and the composition of the graft copolymer is 63 mol% of methyl methacrylate units,
The contents were 28 mol% of styrene units, 4 mol% of six-membered cyclic acid anhydride units, and 5 mol% of methacrylic acid. (v) Production of graft rubber (B-3) Same as production of graft rubber (B-2) except that 26 parts by weight of methyl methacrylate and 14 parts by weight of styrene were added and polymerized and t-butyl methacrylate was not used. Polymerization was carried out by the method and post-treatment was carried out. The refractive index of this graft rubber was 1.525, and the composition of the graft copolymer was 66 mol% of methyl methacrylate units and 34 mol% of styrene units. Example 1 70% by weight of the copolymer (A-1) and 30% by weight of the graft rubber (B-1) were kneaded in a twin-screw extruder and extruded into pellets. The properties of this pellet were measured and the results are shown in Table 2. Example 2 70% by weight of the copolymer (A-2) and 30% by weight of the graft rubber (B-2) were kneaded in the same manner as in Example 1. The properties of this pellet were measured and the results are shown in Table 2. Comparative Example 70% by weight of copolymer (A-2) and 30% by weight of graft rubber (B-3) were kneaded in the same manner as in Example 1. The properties of this pellet were measured and the results are presented.

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Claims (1)

[Claims] 1. 20 to 95 mol% of methyl methacrylate units, general formula (In the formula, R is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group). unit 0.1 to 50 mol%, imide unit of formula (2) 2 to 77 mol%, aromatic vinyl unit 1 to
The viscosity of a methyl ethyl ketone solution containing 70 mol% and 1 to 20 mol% of methacrylic acid units and a 10% by weight copolymer concentration at a temperature of 25°C is 3 to 20%.
50 to 98% by weight of copolymer (A) that is centipoise;
Rubber having a glass transition temperature of -30°C or less contains 30 to 95 mol% of methyl methacrylate units, 5 to 70 mol% of aromatic vinyl units, and 0.1 to 50 methacrylic acid units.
Grafted rubber (B) 2 to 50 mol % of a copolymer grafted with a copolymer which optionally also contains an acid anhydride unit of the above formula (1) and/or an imide unit of the above formula (2)
A transparent methyl methacrylate-based impact-resistant resin composition with excellent heat resistance and impact resistance.