JPH0511141B2 - - 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 of copolymerizing methyl methacrylate, α-methylstyrene, styrene, and maleic anhydride (Japanese Patent Application Laid-open No. 56-81322), poly-α-
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 resins with excellent properties, we have developed a four-component copolymer structure of methyl methacrylate-α-methylstyrene-styrene or vinyltoluene-maleic anhydride with a specific composition. The inventors have discovered that a resin mixture of a copolymer and a polymer containing a methacrylimide ring structural unit can achieve the object, and have completed the present invention. That is, the heat-resistant methacrylic resin composition of the present invention contains (A) methyl methacrylate 40 to 97% by weight (B) α-methylstyrene 1 to 20% by weight (C) styrene or vinyltoluene
A copolymer () obtained by polymerizing a mixture consisting of 1 to 20% by weight and (D) maleic anhydride 1 to 20% by weight, and the 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 (2) 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 40% by weight, the above properties will be lost, and if it exceeds 97% by weight, no improvement in heat resistance can be expected. The preferred ratio is 50
~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, and if it exceeds 20% by weight, productivity and heat decomposition resistance of the copolymer will decrease. The preferred proportion is 3-10% by weight. Furthermore, although styrene or vinyltoluene, which is a component of the copolymer (), is not a component that directly improves heat resistance, it can increase the copolymerization reactivity of maleic anhydride, which is a heat resistance improving component. This indirectly improves heat resistance and at the same time shows a remarkable effect on improving productivity.
If the proportion of (C) in parentheses is less than 1% by weight, heat resistance will indirectly decrease and productivity will also be poor. 20
If it exceeds the weight percentage, the optical properties and weather resistance will deteriorate. The preferred proportion is 5-18% by weight. Examples of the vinyl toluene used include ortho-, meta-, and para-substituted vinyl toluenes, and these may be used alone or as a mixture of two or more. Furthermore, maleic anhydride (D), which is a component of the copolymer (), is a component that improves the heat resistance of the copolymer through interaction with copolymerized α-methylstyrene, styrene, or vinyltoluene. . If the proportion of (D) in parentheses is less than 1% by weight, productivity and heat resistance will be poor; if it exceeds 20% by weight, mechanical properties and optical properties will deteriorate, and boiling resistance will further deteriorate. The preferred proportion is 5-15% by 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, the number of moles of the structural unit derived from styrene or vinyltoluene is β, and the number of moles of the structural unit derived from maleic anhydride is γ, (α+β)/γ is 0.9 Most preferably it is ~1.7. Water resistance if less than 0.9;
A tendency for mechanical properties to decrease is observed, and when it exceeds 1.7, a decrease in optical properties and heat resistance is observed. The second polymer () constituting the heat-resistant methacrylic resin composition of the present invention is for imparting the heat resistance inherent to methacrylimide resin. In other words, if heat resistance is important, polymer ()
It is sufficient to increase the number of methacrylimide ring structural units in the structure, but if mechanical properties are important, the number of methacrylimide ring structural units can be decreased and other structural units (for example, structural units derived from methyl methacrylate) may be used.
It is preferable to increase. 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 condensation 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). In order to obtain a polymer () having a methacrylimide ring structural unit with excellent transparency, the imidizing agent is introduced into a homogeneous solution system in which the raw material methacrylic resin is dissolved in a non-polymerizable solvent, and a thermal decomposition condensation reaction is carried out. After the reaction is allowed to stand, it is preferable to separate and remove volatile substances from the obtained reaction product. 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, methacrylic acid derivatives such as methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, tert-butyl methacrylate, hexyl methacrylate, octyl methacrylate, dodecyl methacrylate; styrene, vinyltoluene, α-methylstyrene, Styrene derivatives such as chlorstyrene; acrylic acid derivatives such as acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, and dodecyl acrylate; Or they are used as a mixture of two or more. 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 toluene and methanol, and a mixture of xylene and 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 having an extrusion rate (g) in 10 minutes 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, the mechanical properties will be poor and 89
If it exceeds % by weight, chemical properties such as boiling resistance will be poor. 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. The present invention will be explained in more detail below with reference to Examples and Comparative Examples. [Examples of the invention] Examples 1 to 3, Comparative Examples 1 and 2 650 g of methyl methacrylate, 50 g of α-methylstyrene, 150 g of styrene, and 150 g of maleic anhydride
2.3 g of t-dodecyl mercaptan was added as a molecular weight regulator to 1000 g of a monomer mixture consisting of the following: 2.3 g of t-dodecyl mercaptan was added as a molecular weight regulator, and the mixture was placed in a separable flask with an internal volume of 2 and equipped with a condenser, a thermometer, and a stirring bar. Next, while stirring, blow nitrogen gas to drive out the air in the system, and then heat until the temperature inside the flask reaches 70℃.
When the temperature reached 15°C, 0.2g of azobisisobutyronitrile was added as a polymerization initiator, and the temperature was increased from 95°C to 15°C.
After holding for a minute, the mixture was cooled to room temperature to obtain a syrup-like partial polymer having a particle size of 600 centipoise. For 1000 g of this partial polymer, 4 g of lauroyl peroxide, 3.0 g of t-dodecyl mercaptan as a molecular weight regulator, 0.3 g of "Tinuvin-P" (trade name, manufactured by Ciba Geigy) as an ultraviolet absorber,
“JP-504” (product name, Johoku Kagaku Co., Ltd.) as a release agent
) 0.2g, “Mark329” (product name,
1 g of Adeka Argus Co., Ltd. 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 made of two tempered glass plates spaced 3 mm apart, and heated to 80°C water. It was polymerized and cured inside. After 30 minutes of checking the time from immersion in hot water until the internal temperature reaches its peak, the mold was taken out of the hot water and heat treated in an air heating oven at 130°C for 2 hours. After cooling, the glass plate was removed to obtain a resin plate with a thickness of about 3 mm. This plate was cut and crushed into pellets of about 3 to 4 mm.
A copolymer () was thus obtained. In the autoclave in Step 5, 1000 g of a sufficiently dried raw material methacrylic resin polymer (manufactured by Mitsubishi Rayon Co., Ltd., trade name: Acrypet VH) and dry toluene were placed.
1000g was charged and dissolved with stirring. The resulting mixture was added to 387.5 g of a solution of methylamine gas dissolved in dry methanol to give a concentration of 40% by weight, heated, dissolved and stirred, and then heated at 230°C for 3 hours at a pressure of 50 kg/cm ²
The methacrylimide ring formation reaction was carried out under the following conditions. The resulting transparent syrup solution was dried in a hot air dryer at 120° C. overnight to remove the solvent, cut and ground into pellets of about 3 to 4 mm. N-methylmethacrylimide ring formation was determined by nuclear magnetic resonance absorption spectrum (FX-90- manufactured by JEOL Ltd.).
Q, 5% by weight solution of d-6 dimethyl sulfoxide,
Internal standard: tetramethylsilane, measured at 120°C)
The measurement and evaluation 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 copolymer () and the polymer () were blended in a Henschel mixer in the proportions shown in Table 1, and then shaped into pellets using a twin-screw extruder at a temperature of 265°C. 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: Japan Steel Works, Ltd., V-17-65 screw type automatic injection molding machine Injection molding conditions: Cylinder temperature 250-260℃, injection pressure 700Kg/cm ² Mold temperature 60℃

【table】

【table】

[Table] Comparative Examples 3 to 5 2.6 g of t-dodecyl mercaptan was added as a molecular weight regulator to 1000 g of a monomer mixture containing methyl methacrylate, α-methylstyrene, and maleic anhydride in the proportions shown in Table 3. This mixture was placed in a 2-volume separable flask 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 to bring the temperature inside the flask to 70°C, and azobisisobutyronitrile was added as a polymerization initiator.
0.25 g was added, and the internal temperature was kept at 95° C. 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, 0.2 g of "Tinuvin-P" (trade name, manufactured by Ciba Geigy) as an ultraviolet absorber,
“JP-504” (product name, Johoku Kagaku Co., Ltd.) as a release agent
) 0.2g, “Mark329” (product name,
1 g of Adeka Argus Co., Ltd. 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 placed between two tubes with a spacing of 3 mm through a polyvinyl chloride gasket.
It was poured into a mold consisting of a thermocouple set in a cell formed from a sheet of tempered glass, and polymerized and hardened in warm water at 80°C. Then, after 30 minutes have passed after immersing the mold in hot water and checking the time until the internal temperature reaches its peak, remove the mold from the warm water, and then
Heat treatment was carried out for 2 hours in an air heating oven at .degree. After cooling, the glass plate was removed to obtain a resin plate with a thickness of about 3 mm. This plate was cut and crushed into pellets of about 3 to 4 mm.

[Table] This pellet is made using a 40mmφ single screw extruder.
It was shaped at 265°C. Using this pellet, injection molding was carried out under the same conditions as in Example 1, and the obtained test pieces were evaluated. The results are shown in Table 4.

[Table] Examples 4 to 6 A monomer mixture consisting of 665 g of methyl methacrylate, 55 g of α-methylstyrene, 140 g of p-methylstyrene and 140 g of maleic anhydride was added to Example 1.
Polymerization was carried out in the same manner as above to obtain a plate-like copolymer with a thickness of 3 mm. After cutting and pulverizing this copolymer, the N-methylmethacrylimide ring-containing polymer of Example 1 and Table 5
The pellets were mixed in a ratio of 1 to 1, and formed into pellets using a twin-screw extruder (temperature: 260°C).The pellets were then injection molded in the same manner as in Example 1, and the test pieces obtained were evaluated. The results are shown in Table 6.

【table】

[Table] Examples 7 to 10, Comparative Examples 6 to 11 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 as shown in Table 7 and varying the various methacrylimidization rates. 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 Co., Ltd.)
Co., Ltd., trade name: Cevian MAS30) and methyl methacrylate-methyl acrylate copolymer (Mitsubishi Rayon Co., Ltd., Acrypet MF) were used. As a comparative example, as shown in Table 7, polymethyl methacrylate resin polymer, methyl methacrylate-
A styrene copolymer and a methyl methacrylate-methyl acrylate copolymer were molded as they were and evaluated. The results are shown in Table 8.

【table】

【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 (A) Methyl methacrylate 40-97% by weight (B) α-methylstyrene 1-20% by weight (C) Styrene or vinyltoluene
A copolymer () obtained by polymerizing a mixture consisting of 1 to 20% by weight and (D) maleic anhydride 1 to 20% by weight, and the 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 The number of moles of structural units derived from α-methylstyrene constituting the copolymer () is α, the number of moles of structural units derived from styrene or vinyltoluene is β, and the number of moles of structural units derived from maleic anhydride is γ.
The heat-resistant methacrylic resin composition according to claim 1, wherein (α+β)/γ is 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 a vinyl monomer or a mixture 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.