JPH0510385B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a transparent heat-resistant methacrylic resin composition. [Technical background of the invention and its problems] Methacrylic resin whose main component is methyl methacrylate has excellent optical properties and weather resistance, and is also compared in terms of mechanical properties, thermal properties, moldability, etc. Due to its well-balanced performance, it is widely used in many fields such as signboards, lighting covers, nameplates, automobile parts, electrical equipment parts, decorations, and miscellaneous goods. Development of new uses is also underway. However, on one side, the heat distortion temperature is around 100℃,
There are many fields in which the development of applications is restricted due to insufficient heat resistance, and there is a deep-rooted demand for improved heat resistance. Many proposals have already been made for methods of improving the heat resistance of methacrylic resins, such as a method of copolymerizing methyl methacrylate and α-methylstyrene, and a method of copolymerizing methyl methacrylate, α-methylstyrene, and maleic anhydride. (Special Publication No. 49-10156), a method for copolymerizing methyl methacrylate, styrene, and maleic anhydride (Special Publication No. 10156),
56-43242), method for copolymerizing methyl methacrylate, α-methylstyrene, styrene and maleic anhydride (JP-A-56-81322), polyα-
A method in which methyl styrene is dissolved in methyl methacrylate and then methyl methacrylate is polymerized (Tokuko Sho
43-1616, Japanese Patent Publication No. 49-8718), method for copolymerizing methyl methacrylate and N-allylmaleimide (Japanese Patent Publication No. 43-9753), copolymerization of methyl methacrylate, α-methylstyrene, and maleimide. A method of copolymerizing methyl methacrylate in the presence of a crosslinked polymer using a polyfunctional monomer, a method of copolymerizing methacrylic acid with methyl methacrylate, a method of copolymerizing methyl methacrylate, α-methylstyrene, and acrylonitrile. Polymerization methods have been proposed. However, since the polymerization rate of the above proposed method is extremely low, productivity is extremely low and it is not practical, mechanical properties, weather resistance, and optical properties are decreased, and the molded product is significantly colored. In either case, the heat resistance is improved to some extent, but the molding area is narrow and the molding processability is poor.
At present, many problems remain before it can be put into practical use. [Objective of the Invention] The object of the present invention is to solve the above-mentioned problems, which reduce the inherent excellent properties of methacrylic resin such as optical properties, mechanical properties, weather resistance, moldability, and productivity. It is an object of the present invention to provide a heat-resistant methacrylic resin composition that is free from heat and has excellent transparency. [Summary of the Invention] In view of the current situation, the present inventors have developed a transparent resin without deteriorating its inherent excellent optical properties, mechanical properties, weather resistance, moldability, productivity, etc. As a result of intensive research into heat-resistant methacrylic resin with excellent properties, we have developed methyl methacrylate-α- with a specific composition.
It was discovered that a resin mixture of a copolymer having a methyl styrene-maleic anhydride ternary copolymer structure and a polymer containing a methacrylimide ring structural unit can achieve the object, and in completing the present invention. It has been reached. That is, the heat-resistant methacrylic resin composition of the present invention consists of (A) 50-98% by weight of methyl methacrylate, (B) 1-25% by weight of Bα-methylstyrene, and (C) 1-25% by weight of maleic anhydride. Copolymer (I) obtained by polymerizing the mixture 1 to 99% by weight and general formula: (In the formula, R represents a hydrogen atom, an aliphatic group having 1 to 10 carbon atoms, or a hydrocarbon group having 5 to 10 carbon atoms including an alicyclic group or an aromatic group) It is characterized by consisting of 1 to 99% by weight of a polymer () containing 2% by weight or more of units. Methyl methacrylate (A) used to constitute the copolymer () in the composition of the present invention is:
This component maintains the original optical properties, weather resistance, or mechanical properties of the methacrylic resin and improves its compatibility with the polymer containing methacrylimide ring structural units. If the proportion of (A) in parentheses is less than 50% by weight, the above properties will be lost, and if it exceeds 98% by weight, no improvement in heat resistance can be expected. The preferred ratio is 60
~80% by weight. In addition, α-methylstyrene (B), which is a constituent component of the copolymer (), is a component that directly improves heat resistance. It is a component that indirectly improves heat resistance by increasing . If the proportion of (B) in parentheses is less than 1% by weight, productivity and heat resistance will be poor; if it exceeds 25% by weight, mechanical properties and optical properties will deteriorate, and boiling resistance will tend to deteriorate. show. The preferred ratio is 5-15
Weight%. Furthermore, maleic anhydride (C), which is a component of the copolymer (), is a copolymerized α-
A component that improves the heat resistance of the copolymer through interaction with methylstyrene. If the proportion of (C) in parentheses is less than 1% by weight, productivity and heat resistance will be poor; if it exceeds 25% by weight, mechanical properties will deteriorate and boiling resistance will further deteriorate. The preferred ratio is 5-25
Weight%. In the composition of the present invention, considering the overall balance of resin properties such as heat resistance, mechanical properties, optical properties, and moldability of the blended resin finally obtained, α in the copolymer () - When the number of moles of the structural unit derived from methylstyrene is α and the number of moles of the structural unit derived from maleic anhydride is β, it is most preferable that α/β is 0.9 to 1.7. When α/β is less than 0.9, water resistance and mechanical properties tend to decrease, and when it exceeds 1.7, optical properties and heat resistance tend to decrease. Second polymer () constituting the composition of the present invention
is for imparting the inherent heat resistance of methacrylimide resin. In other words, when placing emphasis on heat resistance, it is sufficient to increase the methacrylimide ring structural unit in the polymer (); when placing importance on mechanical properties, the methacrylimide ring structural unit may be reduced and other It is preferable to increase the number of structural units (for example, structural units derived from methyl methacrylate). In the above methacrylimide ring structural unit, examples of the aliphatic group having 1 to 10 carbon atoms represented by R include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine,
Examples include linear and branched types such as heptylamine, octylamine, nonylamine, and decylamine. Examples of hydrocarbon groups having 5 to 10 carbon atoms containing alicyclic groups or aromatic groups include cyclopentylamine, cyclohexylamine, aniline, orthotoluidine, metatoluidine, paratoluidine, 2,4,6-trimethylaniline, and paratoluidine. Examples include ethylaniline. The proportion of methacrylimide ring structural units in the polymer () is
It is usually 2% by weight or more, preferably 10% by weight or more. If this proportion is less than 2% by weight, sufficient heat resistance cannot be expected. The weight average molecular weight of the polymer () is usually 40,000 to 500,000, preferably 40,000 to 100,000.
Ten thousand. If the molecular weight is less than 40,000, the mechanical strength will be poor, and if it exceeds 500,000, the moldability will be poor. Further, the degree of polymerization is usually 200 to 3000, preferably 400 to 2000. There are no particular restrictions on the method for producing the polymer () containing a methacrylimide ring structure component, but
A method of subjecting a methacrylic resin polymer to a thermal decomposition bonding reaction using at least one imidizing agent selected from the group consisting of ammonia, an ammonia generator, a primary amine, and a primary amine generator (for example,
US Patent No. 2146209, West German Patent No. 1077872,
No. 1242369). Polymer of methacrylimide ring structural unit with excellent transparency ()
To obtain the above, the above imidizing agent is introduced into a homogeneous solution system in which the raw material methacrylic resin is dissolved in a non-polymerizable solvent to cause a thermal decomposition condensation reaction, and then volatile substances are separated from the resulting reaction product. It is preferable to remove it. The raw material methacrylic resin is a copolymer containing a methacrylic acid derivative capable of forming a methacrylimide ring structural unit obtained by reacting with the imidizing agent. Examples of methacrylic acid derivatives include:
Methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid
Tert-butyl, hexyl methacrylate, octyl methacrylate, dodecyl methacrylate, etc. are used. Among these, methyl methacrylate is preferred. Examples of copolymerizable components include vinyl monomers that can be copolymerized with methacrylic acid derivatives.
For example, styrene derivatives such as styrene, vinyltoluene, α-methylstyrene, chlorostyrene; acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate,
Examples include acrylic acid derivatives such as dodecyl acrylate. Among these, styrene is preferred. Examples of the imidizing agent for forming the methacrylimide ring structural unit include ammonia, methylamine, butylamine, urea, and 1,3 dimethylurea. Among these, methylamine is preferred from the viewpoint of heat resistance. The non-polymerizable solvent may be any non-polymerizable solvent that can dissolve the raw material methacrylic resin and the product methacrylic imide ring structure component-containing polymer, such as benzene, methanol, a mixed solvent of tolumene/methanol, or a mixed solvent of xylene/methanol. Solvents etc. are used. The polymer () is usually 5000 ppm or less, preferably 5000 ppm or less, in order to prevent oxidative deterioration of the polymer.
Under an oxygen concentration atmosphere of 1000ppm or less, usually 150~
Produced at a temperature of 350°C, preferably 170-250°C. In addition, in order to prevent hydrolysis of the side chains of the polymer, it is usually 5000 ppm or less, preferably 1000 ppm or less.
Produced under anhydrous atmosphere: The composition of the present invention has a flow rate (FR) of 0.5 to 75 (according to ASTM D-1238 at 230°C, 10
It is particularly useful as a molding material using a 10 minute extrusion rate (g) under a load of Kg/ ^cm2 . The blending ratio of the methacrylic resin composition of the present invention is
In the composition, the amount of the copolymer () is usually 1 to 99% by weight, preferably 5 to 95% by weight. If this proportion is less than 1% by weight, heat resistance will be poor, and if it exceeds 99% by weight, no improvement in mechanical properties can be expected. There are no particular limitations on the method for producing the composition of the present invention, but for example, the copolymer () is produced by bulk polymerization, suspension polymerization, etc. in accordance with a conventional method, and the resulting copolymer () and polymer After mixing with coalescence (),
A method of producing a blended resin by melting, kneading, and extruding at a temperature of 200 to 300°C, and after dissolving the polymer in the monomer mixture used to produce the polymer, it contains a suspending and dispersing agent. Suspension polymerization or bulk polymerization in an aqueous medium can be employed. Additives such as ultraviolet absorbers, release agents, antioxidants, mold release agents, dyes and pigments may be added to the composition of the present invention, if necessary. EXAMPLES The present invention will be explained in more detail with reference to Examples and Comparative Examples below. [Examples of the Invention] Example 1, Comparative Examples 1 to 3 To 1000 g of a monomer mixture containing methyl methacrylate, α-methylstyrene, and maleic anhydride in the proportions shown in Table 1, t was added as a molecular weight regulator. - 2.5 g of dodecyl mercaptan were added and the mixture was placed in a separable flask of internal volume 2 equipped with a condenser, thermometer and stirring bar. Next, while stirring, nitrogen gas was blown in to drive out the air in the system, and then heated and when the temperature inside the flask reached 70°C, 0.2 g of 2,2'-azobis-(2,4-dimethylvaleronitrile) was added. and internal temperature 95
The mixture was kept at ℃ for 15 minutes and cooled to room temperature to obtain a syrup-like partial polymer. For 1000 g of this partial polymer, 4 g of lauroyl peroxide, 3.0 g of t-dodecyl mercaptan as a molecular weight regulator, and ``tinuvin'' as an ultraviolet absorber.
P” (trade name, manufactured by Ciba Geigy) 0.3g, “JP-504” (trade name, manufactured by Johoku Kagaku Co., Ltd.) as a release agent 0.2
g, 1 g of "MarK 329" (trade name, manufactured by Adeka Argus Co., Ltd.) as a stabilizer, and 1 g of stearic acid monoglyceride as a mold release agent were added, and the mixture was sufficiently stirred to dissolve. This partial polymer mixture was injected through a polyvinyl chloride gasket into a mold consisting of a thermocouple set in a cell formed by two tempered glass plates spaced 3 mm apart, and heated to 80°C water. It was polymerized and cured inside. After 30 minutes had elapsed from the time the mold was immersed in the hot water until the internal temperature reached its peak, the mold was taken out of the hot water and heat treated in an air heating furnace at 130°C for 2 hours. After cooling, the glass plate was removed to obtain a resin plate with a thickness of approximately 3 mm. This plate was cut and crushed into pellets of about 3 to 4 mm.
A copolymer () was thus obtained.

[Table] 1000 g of sufficiently dried raw material methacrylic resin polymer (manufactured by Mitsubishi Rayon Co., Ltd., trade name: AcryPets VH) and dry toluene were placed in the oaklave in Step 5.
1000g was charged and dissolved with stirring. The resulting mixture was added to 387.5 g of a solution of 40% concentration by dissolving methylamine gas in dry methanol, heated, dissolved and stirred, and then dissolved in methacrylic acid at 230°C for 3 hours at a pressure of 50 kg/ ^cm2 . An imide ring formation reaction was performed.
The resulting clear syrup solution was placed in a hot air dryer.
After drying at 120° C. for one day and night to remove the solvent, the pellets were cut and ground into pellets of about 3 to 4 mm. N-methylmethacrylimide ring formation was determined by nuclear magnetic resonance absorption spectroscopy (FX-90-Q, manufactured by JEOL Ltd.,
The results were confirmed by the absorption at 2.95 ppm (δ value). Based on the area ratio, the N-methylmethacrylimidation rate was 60%. When this is heated and molded to create a test piece, it becomes a transparent test piece, and the practical heat resistance temperature (heat distortion temperature) (HDT) is
It was 125℃. In this way, an N-methylmethacrylimide ring structure-containing polymer () was obtained. The above copolymer () and the above polymer ()
After mixing at a polymerization ratio of 60/40, using an extruder
Shape at 200-270℃ and pelletize (extrusion temperature 270℃)
℃). This pellet was injection molded under the following conditions, and the evaluation results shown in Table 2 were obtained from the resulting test piece (110 mm x 110 mm x 2 mm thickness). Injection molding machine: V-17-65 screw type automatic injection molding machine manufactured by Japan Steel Works, Ltd. Injection molding conditions: Cylinder temperature 250-260℃, injection pressure 700Kg/cm ² Mold temperature 50℃

[Table] Example 2 The composition of methyl methacrylate, α-methylstyrene, and maleic anhydride was changed to MMA/α-
The polymer () obtained as MeSt/MAH=750/140/110 (weight ratio) and the N used in Example 1
A resin composition of the present invention was prepared by repeating the experiment in the same manner as in Example 1, except that the weight ratio of the methyl methacrylimide ring structure-containing polymer () was changed to 80/20. The results obtained are shown in Table 3.

【table】

[Table] Visually judge the degree of whitening.
Comparative Examples 4 to 6 Polymer () was prepared using 1000 g of a monomer mixture containing methyl methacrylate, α-methylstyrene, and maleic anhydride in the proportions shown in Table 4.
was produced in the same manner as in Example 1 to obtain a 6 mm thick plate.
This plate was cut and crushed, and then shaped into pellets using an extruder. The pellets alone were injection molded in the same manner as in Example 1 without blending the N-methylmethacrylimide ring-containing polymer (2), and the physical properties of the obtained test pieces were evaluated. The results are shown in Table 5.

【table】

【table】

[Table] Examples 3 to 5, Comparative Examples 7 and 8 A monomer mixture consisting of 560 g of methyl methacrylate, 240 g of α-methylstyrene, and 200 g of maleic anhydride was polymerized in the same manner as in Example 1, and a thickness of 3
A plate-like copolymer of mm was obtained. Cutting this copolymer,
After pulverization, the mixture was mixed with the methylmethacrylimide ring-containing polymer of Example 1 in the proportions shown in Table 6, and shaped into pellets using a twin-screw extruder at a rotation speed of 250 rpm and a temperature of 260°C. A test piece obtained by injection molding in the same manner as in Example 1 was evaluated. The results are shown in Table 7.

【table】

【table】

[Table] Examples 6 to 9, Comparative Examples 9 to 14 Copolymers () were produced in the same manner as in Example 1. The methacrylimide-containing polymer (2) was produced in the same manner as in Example (2), but by changing the methylamine charge and varying the methacrylimidation rate as shown in Table 8. The raw material methacrylic resin polymers are polymethyl methacrylate (manufactured by Mitsubishi Rayon Co., Ltd., product name: Acrypet VH), methyl methacrylate-styrene copolymer (manufactured by Daicel Corporation)
(trade name: Sebian MAS30) and a methyl methacrylate/methyl acrylate copolymer (Acrypet MF, manufactured by Mitsubishi Rayon Co., Ltd.) were used.
Polymethyl methacrylate resin polymer, methyl methacrylate as raw material methacrylic resin polymer
A styrene copolymer and a methyl methacrylate-methyl acrylate copolymer were formed as they were and comparatively evaluated. The results are shown in Table 9.

【table】

[Table] [Effects of the Invention] As detailed above, the methacrylic resin composition of the present invention has excellent optical properties, mechanical properties, weather resistance, moldability, productivity, etc. inherent to methacrylic resin. It has good transparency and heat resistance while retaining its properties, and its industrial value is extremely large.

Claims (1)

[Claims] 1. Obtained by polymerizing a mixture consisting of (A) 50-98% by weight of methyl methacrylate, (B) 1-25% by weight of α-methylstyrene, and (C) 1-25% by weight of maleic anhydride. Copolymer (I) I
1-99% by weight and general formula: (In the formula, R represents a hydrogen atom, an aliphatic group having 1 to 10 carbon atoms, or a hydrocarbon group having 5 to 10 carbon atoms including an alicyclic group or an aromatic group) A heat-resistant methacrylic resin composition comprising 1 to 99% by weight of a polymer () containing 2% by weight or more of units. 2 When α is the number of moles of the structural unit derived from α-methylstyrene constituting the copolymer (I) and β is the number of moles of the structural unit derived from maleic anhydride, α/β is
The heat-resistant methacrylic resin composition according to claim 1, which has a molecular weight of 0.9 to 1.7. 3. The heat resistance according to claim 1, wherein the polymer () comprises 2% by weight or more of methacrylimide ring structural units and less than 98% by weight of structural units derived from vinyl monomers or mixtures of vinyl monomers. methacrylic resin composition. 4. The heat-resistant methacrylic resin composition according to claim 3, wherein the vinyl monomer is at least one selected from the group consisting of methacrylic acid derivatives, styrene derivatives, and acrylic acid derivatives.