JPS6343404B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention describes a method for producing a novel modified copolymer, and more specifically, the present invention provides a method for producing a novel modified copolymer, and more specifically, a method for producing a modified copolymer, which has a balance between physical properties such as mechanical strength, oil resistance, heat resistance, and thermal stability, and processability depending on the purpose of use. The present invention relates to a method for optionally producing a thermoplastic modified copolymer that is clear and transparent. Conventional technology In recent years, excellent heat resistance,
There is a growing demand for resins that have mechanical strength and oil resistance, are transparent, and are inexpensive. By the way, among the resins currently available on the market, polycarbonate resin is known as a resin that is colorless and transparent and has excellent mechanical strength and heat resistance. However, this resin is an engineering plastic and is expensive, so it has not been widely used. Among thermoplastic resins, methyl methacrylate resin is commercially available at a relatively low price and has mechanical strength, oil resistance, weather resistance, and outstanding colorless transparency. has the disadvantage of being inferior in heat resistance, particularly in terms of thermal deformability and thermal decomposition. Therefore, a method of copolymerizing methyl methacrylate and various comonomers has been proposed as a method for further improving the heat resistance without impairing the desirable physical properties of methyl methacrylate resin. By the way, the comonomers used in this case include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, unsaturated dicarboxylic acid anhydrides, α-
Aromatic vinyl compounds such as methylstyrene are common, but when these comonomers are introduced into a system based on methyl methacrylate,
All of these resins generate gas at molding temperatures of 200 to 260°C, and they produce molded products that are inferior in appearance to methyl methacrylate resin, so they have not yet reached the stage of practical use. Under these circumstances, the present inventors conducted intensive research to improve both the heat deformability and thermal stability of methyl methacrylate resin, and first developed the general formula in the molecule. It has been found that the first object can be achieved by forming a six-membered cyclic acid anhydride unit represented by the formula (R ₁ and R ₃ are hydrogen atoms or methyl groups). This six-membered cyclic acid anhydride unit is secondarily derived from an acrylic acid or methacrylic acid unit. However, even resins having high heat deformability due to the introduction of six-membered cyclic acid anhydride units are not necessarily satisfactory in terms of heat resistance compared to polycarbonate. On the other hand, by reacting a homopolymer or copolymer of methyl methacrylate with ammonia or a primary amine in an extruder, the general formula (R ₁ and R ₂ in the formula are hydrogen atoms or methyl groups,
_R3 is a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group) (Japanese Patent Application Laid-open No. 71928/1983)
It has been known. However, although such polymers having six-membered ring imide units have improved heat resistance, they have the drawback of low mechanical strength and moldability. Problems to be Solved by the Invention The present invention is directed to a methyl methacrylate copolymer that has a balance of physical properties such as mechanical strength, oil resistance, heat resistance, and thermal stability, and moldability, depending on the purpose of use. The purpose of this work is to provide a method for arbitrarily producing . Means for Solving the Problems The present inventors have conducted various studies to develop a methyl methacrylate copolymer with well-balanced physical properties comparable to polycarbonate resins. In addition, by imidizing a part of the six-membered cyclic acid anhydride units in the copolymer containing aromatic vinyl compound units, methacrylic acid units, and six-membered cyclic acid anhydride units, the heat deformability is improved. We have found that mechanical strength and fluidity can be maintained by appropriately selecting the degree of imidization, and based on this knowledge, we have accomplished the present invention. That is, the present invention comprises (A) 29 to 95% by weight of methyl methacrylate units, and (B) 1 to 95% by weight of aromatic vinyl compound units.
67% by weight, (C) 1 to 10% by weight of methacrylic acid units, and
(D) General formula When reacting a copolymer consisting of 3 to 50% by weight of six-membered cyclic acid anhydride units represented by ammonia or organic primary amine, the amount of ammonia or organic primary amine to be used is adjusted to (A) 29 to 95% by weight of methyl methacrylate units, characterized in that the amount is greater than 0.2 equivalents based on the anhydride units and is adjusted to an amount sufficient to obtain the required amidation rate; B) 1 to 67% by weight of aromatic vinyl compound units, (C)
1 to 10% by weight of methacrylic acid units, and (D) general formula (R in the formula is a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group) consisting of 3 to 50% by weight of six-membered ring units,
and a copolymer prepared such that the weight ratio of the six-membered cyclic imide units represented by the general formula () to the six-membered cyclic acid anhydride units represented by the general formula () is more than 1/10 and 10 or less. This is due to the manufacturing method. The methyl methacrylate unit (A) in the copolymer used as a raw material in the method of the present invention is the main monomer unit of the copolymer, and plays a role in improving mechanical strength and oil resistance. The content ranges from 29 to 95% by weight based on the copolymer. When this content is less than 29% by weight, the mechanical strength of the copolymer decreases, and when this content is less than 29% by weight,
If it exceeds this amount, the copolymer's fluidity and thermal stability during heating will decrease. Next, the aromatic vinyl compound unit (B), which is the second monomer unit, plays a role in improving the fluidity and thermal stability of the copolymer during heating, and its content The amount ranges from 1 to 67% by weight, based on the copolymer. If the content is less than 1% by weight, the fluidity and thermal stability during heating of the copolymer will decrease, while if it exceeds 67% by weight, the mechanical strength and oil resistance will decrease. Furthermore, the total amount of the methyl methacrylate units and aromatic vinyl compound units in this copolymer is preferably in the range of 49 to 96% by weight; if this amount is less than 49% by weight, the copolymer becomes brittle. On the other hand, if it exceeds 96% by weight, the thermal deformability and thermal stability of the copolymer will decrease. Examples of the aromatic vinyl compound unit include monomer units such as styrene, α-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, and p-chlorostyrene, Among these, styrene units are the most common. In addition, the methacrylic acid unit (C) in this copolymer plays a role in increasing the heat deformability of the copolymer, and its content is 1 to 10% by weight based on the weight of the copolymer. If the amount exceeds 10% by weight, gas is generated during injection molding at a temperature of 200° C. or higher, which impairs the appearance of the molded product, which is not preferable. The six-membered cyclic acid anhydride unit (D) in the copolymer of the present invention plays a role in increasing the heat distortion temperature and thermal stability. ~50% by weight, preferably 10-40% by weight
is within the range of If this amount is less than 3% by weight, no improvement in heat deformability and thermal stability can be expected;
If it exceeds 100%, the heat deformation temperature of the copolymer will be significantly increased, but the mechanical strength will decrease and the moldability will also decrease. Copolymers having such monomer units (A) to (D) can be produced by radical copolymerization of required amounts of the corresponding monomers. There are no particular restrictions on the polymerization method, but
Particularly preferred is a continuous base polymerization method or a continuous solution polymerization method, and in order to make the composition of the copolymer as uniform as possible, complete mixing in the polymerization reactor is preferred. In the case of continuous solution polymerization, examples of solvents include aromatic hydrocarbons such as toluene and ethylbenzene, ketones such as acetone, methyl ethyl ketone, methyl imbutyl ketone, and cyclohexanone, alkyl or cycloalkyl alcohols having 1 to 6 carbon atoms, and tetrahydrofuran. Ethers such as dioxane and ethylene glycol monoalkyl ethers are used. In the method of the present invention, a copolymer having the above monomer units (A) to (D) is reacted with ammonia or an organic primary amine, and a part of the monomer units of (D) are imidized. However, for this imidization, for example, the raw material copolymer is placed in an autoclave, then ammonia or organic primary amine is added in a solution state, and the reaction is carried out at a temperature of 200 to 270°C for 1 to 5 hours, or, This can be carried out by using an extruder, continuously supplying the raw material copolymer in a molten state with ammonia or an organic primary amine, mixing and extruding it, and then cyclizing it into an imide in a reduced pressure chamber. . The organic primary amine used in this case may be either aliphatic or aromatic. In addition, as ammonia,
Liquid ammonia, ammonia gas, aqueous ammonia can be used, and examples of aliphatic primary amines include methylamine, ethylamine, n-
Examples include propylamine, isopropylamine, butylamine, benzylamine, hexylamine, cyclohexylamine, allylamine, etc.
These can also be used as aqueous solutions. Examples of aromatic amines include aniline, o-
Examples include toluidine, p-toluidine, o-chloroaniline, p-chloroaniline, 2,4,6-trichloroaniline, α-naphthylamine, β-naphthylamine, and 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. These ammonia or organic primary amines are used in an amount of more than 0.2 equivalents, usually 0.3 to 1.4 equivalents, based on the six-membered cyclic acid anhydride units, ie, (D) units, in the raw material copolymer. This amount is closely related to the imidization rate of the (D) unit, with the imidization rate being about 9% at 0.2 equivalents, 27% at 0.4 equivalents, 45% at 0.7 equivalents, and 91% at 1.4 equivalents. In this way, according to the method of the present invention, by increasing or decreasing the amount of ammonia or organic primary amine used, the weight ratio of the six-membered cyclic imide unit to the six-membered cyclic acid anhydride unit in the molecule can be reduced to 1/10. Any copolymer ranging from more than 10 can be obtained. If this weight ratio is less than 1/10, the improvement in physical properties due to imidization is insufficient. The greater the number of six-membered ring imide units, the better the mechanical strength, heat resistance, and thermal stability of the copolymer obtained, but the moldability and water resistance tend to decrease. Copolymers with appropriate physical properties can be obtained. The amount of each monomer unit in the copolymer obtained by the method of the present invention can be easily determined by using, for example, infrared spectroscopy or other analytical methods. That is, methyl methacrylate units are 1730
cm ^-1 , six-membered cyclic acid anhydride units are 1800 cm ^-1 and 1760 cm
This can be done by utilizing characteristic absorption at ^-1 . In addition, in the case of a six-membered ring imide unit, the N-substituted product has a clear absorption at 1670 cm ^-1 ,
It can be distinguished from the 1730 cm ^-1 of the methyl methacrylate unit, but the absorption at 1700 cm ^-1 is the same as that of the methyl methacrylate unit.
Since it is difficult to separate from 1730 cm ^-1 , it is preferable to use a nitrogen content determination method based on elemental analysis to quantify this six-membered ring imide unit. On the other hand, the neutralization titration method is most preferable for quantifying acrylic acid or methacrylic acid units, and rapid titration with an alcoholic NaOH solution in acetone can be used to quantify acrylic acid or methacrylic acid units separately from six-membered cyclic acid anhydride units. For quantitative determination of aromatic vinyl compound units, an infrared spectrophotometer is generally used, but especially when the amount is small, an ultraviolet absorption method is used. Note that when at least 2% by weight of six-membered ring imide units are present based on the total weight of the copolymer, a remarkable improvement in heat deformability is observed, so imidization is not carried out until this amount of six-membered ring imide units are produced. is advantageous. The copolymer thus obtained is intermolecularly crosslinked, does not form a gel, is soluble in organic solvents such as dimethylformamide, and exhibits complete thermoplasticity. Effects of the Invention According to the method of the present invention, physical properties such as mechanical strength, oil resistance, heat resistance, and thermal stability, moldability, and water resistance can be improved by increasing or decreasing the amount of ammonium or organic primary amine used. Between physical properties such as
Since methyl meccrylate copolymers having different levels of balance can be arbitrarily obtained, there is an advantage that copolymers with an appropriate balance of physical properties can be provided depending on the purpose of use. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. In addition, the measurement method of each physical property is as follows. (1) Vikatsu softening temperature: ASTM-D1525 (2) Tensile strength: ASTM-D638 (3) Bending strength and flexural modulus: ASTM-D790 (4) Heating distortion temperature: ASTM-D648 (5) Color tone: Injection Visually observe the molded piece. (6) Thermal stability: Expressed as the temperature at which the weight loss of the polymer is 1% in thermobalance analysis under conditions of a heating rate of 10°C/min in a nitrogen stream. (7) MFI (Melt flow index): JIS K 7210 230
℃, 3.8g load condition. (8) Saturated water absorption rate: A 0.2mm thick sheet is compression molded and immersed in water at 23℃. Weight gain due to water absorption reaches equilibrium in 10 days. Reference Example 1 A mixed solution consisting of 11 parts by weight of styrene, 9 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 was prepared, and this mixed solution was continuously mixed at a rate of 0.5/hr. The mixture was then supplied 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 composition analysis using an infrared spectrophotometer of this copolymer were as follows: 15% by weight of styrene units, 70% by weight of methyl methacrylate units, 4% by weight of methacrylic acid units, and 6-membered cyclic acid anhydride units. It was 11% by weight. Reference example 2 6 parts by weight of styrene, 22 parts by weight of methacrylic acid, 32 parts by weight of methyl methacrylate, 40 parts by weight of cyclohexanone
A mixed solution consisting of 0.18 parts by weight of octyl mercaptan and 0.18 parts by weight of octyl mercaptan was prepared, and polymerization was carried out in the same manner as in Example 1 except for the following. Composition analysis of the obtained copolymer revealed that it contained 10% by weight of styrene units, 50% by weight of methyl methacrylate units, 5% by weight of methacrylic acid units, and 35% by weight of six-membered cyclic acid anhydride units. Example 1 0.5 kg of the copolymer obtained in Reference Example 1 was charged in the form of pellets into an autoclave No. 5, and then 3.0 kg of dimethylformamide was added, stirred to dissolve the entire amount, and then 0.4 kg per unit amount of six-membered cyclic acid anhydride was added. Prepare 28% ammonia water containing an equivalent amount of ammonia,
It was treated at 75°C for 2 hours. Take out the reaction solution and
After the polymer was precipitated with hexane and purified, the copolymer was treated in a volatilization furnace at 250° C. and 16 torr for 2 hours. The final product was almost colorless and transparent, and measurements using an infrared spectrophotometer showed a decrease in absorption at 1800 cm ^-1 and 1760 cm ^-1 , which is characteristic of six-membered cyclic acid anhydrides. The formation of a six-membered ring imide was observed from the new absorption at 1700 cm ^-1 . From the nitrogen content determined by elemental analysis, the six-membered ring imide unit was 3% by weight. Next, by varying the amount of ammonia charged,
The same experiment was repeated by changing the amount of modification of six-membered cyclic acid anhydride units to six-membered cyclic imide units. The composition and physical properties of the copolymer thus obtained are shown in Table 1 together with those of the raw material copolymer. As is clear from this table, if the weight ratio of the six-membered cyclic imide unit to the six-membered cyclic acid anhydride unit in the molecule is less than 1/10, almost no change in physical properties will be observed, so it is necessary to increase it more than that. It is.

[Table] * Comparative Example Example 2 0.5 kg of the copolymer obtained in Reference Example 2 was charged in the form of pellets with 3 kg of dimethylformamide and dissolved in the autoclave No. 5, and then 0.3 equivalent of the six-membered cyclic acid anhydride unit was added. Aqueous ammonia containing ammonia was charged, and the reaction was carried out at 75°C for 2 hours. The reaction product was a colorless and transparent viscous liquid. Next, this liquid was treated in a volatilization furnace at 270° C. and 5 torr for 2 hours. The finally obtained reaction product was slightly yellowish and transparent. The results of compositional analysis and other properties are shown in Table 2 along with those of the raw material copolymer. Example 3 Imidization treatment was carried out in the same manner as in Example 2 except that 0.3 equivalent of methylamine was used instead of 0.3 equivalent of ammonia in Example 2. The reaction product was slightly yellowish but transparent. When this N-methyl-substituted six-membered ring imide was measured using an infrared spectrophotometer, a new absorption was observed at 1670 cm ^-1 and it could be clearly distinguished from the imide produced by ammonia. Its properties are shown in Table 2.

【table】

【table】

[Table] Soluble.

Claims (1)

[Claims] 1 (A) 29 to 95% by weight of methyl methacrylate units, (B)
1 to 67% by weight of aromatic vinyl compound units, (C) 1 to 10% by weight of methacrylic acid units, and (D) general formula When reacting a copolymer consisting of 3 to 50% by weight of six-membered cyclic acid anhydride units represented by ammonia or organic primary amine, the amount of ammonia or organic primary amine to be used is adjusted to (A) 29 to 95% by weight of methyl methacrylate units, characterized in that the amount is greater than 0.2 equivalents based on the anhydride units and is adjusted to an amount sufficient to obtain the required amidation rate; B) 1 to 67% by weight of aromatic vinyl compound units, (C)
1 to 10% by weight of methacrylic acid units, and (D) general formula as well as (R in the formula is a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group) consisting of 3 to 50% by weight of six-membered ring units,
and a copolymer in which the weight ratio of the six-membered cyclic imide units represented by the general formula () to the six-membered cyclic acid anhydride units represented by the general formula () is adjusted to a range of more than 1/10 and 10 or less. Production method.