JPS6011926B2 - Method for producing transparent impact-resistant methyl methacrylate resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a moldable methacrylic resin composition that has excellent transparency, impact resistance, and weather resistance.

In particular, the present invention relates to a method for producing a methacrylic resin, which has a simple and economical production process and is particularly excellent in impact resistance and transparency near room temperature. Methacrylic resin is widely used due to its excellent transparency, gloss, and weather resistance.
Due to unsatisfactory mechanical properties such as toughness and impact resistance, its applications are limited. Many methods have been proposed to improve this drawback, but the most common method is to use a resinous monomer such as methyl methacrylate in the presence of a rubbery polymer latex, known as the so-called transparent A matrix. There is a so-called graft method, typified by a method of emulsion polymerization of the body. However, since an emulsifier is used in this case, the means for recovering the polymer from the emulsion after emulsion polymerization is complicated, and it is difficult to completely prevent impurities from being mixed into the final product, which may cause performance problems. In addition, in order to ensure good transparency, it is necessary to strictly match the refractive index of the elastomer polymer and the hard resin that is the matrix. The elastomeric monopolymer has to be produced by copolymerization, and the copolymerization reaction is not only difficult to control but also complicated in terms of process. Furthermore, when a copolymer containing butadiene is used as an elastomeric polymer, it is easily degraded by light;
Since double bonds remain, it is inevitable that the weather resistance will deteriorate. For this reason, attempts have been made to use elastomer materials with no residual double bonds, such as acrylic acid alkyl ester polymers, ethylene-vinyl acetate copolymers, or ethylene-propylene copolymers. In some cases, the current situation is that sufficient impact strength cannot be obtained unless the rubber content is higher than when using Gen-based rubber. In view of the above-mentioned current situation, the present inventors have developed a method that has excellent weather resistance and does not require too strict consideration of matching the refractive index between the elastomer material and the hard resin.
The present invention was achieved through intensive research aimed at obtaining a highly impact-resistant methacrylic resin that has good transparency and can be manufactured through an economical process.

That is, the gist thereof is to polymerize methyl methacrylate or a monomeric polymer mainly composed of methyl methacrylate in an aqueous medium at a temperature of 80 qo or more without using an emulsifier to form a hard resin emulsion. Solubility in water in the presence of this emulsion is 1.5%
(20oo) or less acrylic acid ester as the main component,
and a monomeric polymer containing a specific amount of methyl methacrylate as an essential component and polymerizing to give an elastomeric polymer (
The present invention relates to a method for producing a methyl methacrylate resin having excellent transparency, impact resistance, and film resistance, which comprises adding and polymerizing an elastomeric monomer (hereinafter sometimes referred to as an elastomeric monomer). To further explain the present invention in detail, methyl methacrylate 50
An unsaturated monomer polymer consisting of ~10% by weight and 0-5% by weight of one or more unsaturated monomers copolymerizable with methyl methacrylate is persulfated in an aqueous medium without the use of emulsifiers. and a reducing sulfoxy compound in the presence of a redox catalyst and a molecular weight regulator at a polymerization temperature of 80 qo.
Heterogeneous polymerization was carried out under the above conditions to prepare an emulsion of a rigid thermoplastic polymer (2) with a controlled molecular weight, and then in this emulsion, 'a} had a solubility in water of 1.5%.
(20 qo) or less alkyl acrylate 50-9 wt% {b} methyl methacrylate 3-4 wt% {c}
0 to 4% by weight of monomers having copolymerizable double bonds,
'd} 0.1 to 5% by weight of a polymerizable monomer that can be allyl, metaallyl or crotyl ester of Q.8 monounsaturated carboxylic acid or dicarboxylic acid, 'e} Copolymerizable polyfunctional crosslinking capacity A monomer mixture comprising 0 to 5% by weight of a monomer and which, when copolymerized, yields a copolymer exhibiting a glass transition temperature of 250 or lower. [This is a method for producing a highly impact-resistant transparent methyl methacrylate resin, which is characterized in that B' is added in one or several stages and polymerization is carried out without adding an emulsifier.

The first point of the present invention is that a monomeric polymer mainly composed of methyl methacrylate is prepared in an aqueous medium in the presence of a redox catalyst consisting of a persulfate and a reducing sulfoxy compound without using a so-called emulsifier. The purpose is to obtain an emulsion of a hard thermoplastic resin by performing polymerization at a temperature of 80 qo or more. As polymerization initiators for this emulsifier-free emulsion polymerization, known water-soluble peroxides such as potassium persulfate and ammonium persulfate, and sodium thiosulfate,
Redox systems in combination with reducing sulfoxy compounds such as sodium sulfite are preferably used. It is believed that the initiator fragment S04- produced by the redox reaction contributes to maintaining the stability of the emulsion at the polymer end. Therefore, it is important to raise the polymerization temperature to speed up the redox reaction of the initiator system and to increase the initiator efficiency in the early stages of polymerization. However, if the polymerization temperature is too high or too low, the resulting emulsion will become unstable, so the temperature range is 80°C.
It is preferable to maintain the temperature at 90 qo to 90 qo, and especially at the initial stage of polymerization, it is preferable to maintain the temperature at 85 qo or higher. In this polymerization system that does not use an emulsifier, no new particles are generated during the polymerization or even if a new monomer is added, and so-called seed polymerization is completely carried out. At this stage, by adjusting the polymerization conditions such as the amount of initiator and the monomer concentration, an emulsion with a uniform particle size usually in the range of 0.3 to 0.6 mm can be stably obtained. Regarding the aqueous dispersion polymerization of methyl methacrylate and its related monomers in the absence of an emulsifier, Japanese Patent Publication No. 49-561 and Japanese Patent Publication No. 49-
31316, JP-A-50-61484, etc., propose a method of adding divalent copper ions as a polymerization accelerator to a known redox catalyst system to obtain a stable polymer latex with a particle size of 0.3 French or less. .

Although this method is recognized as an excellent method for obtaining stable latex with small particle size, the presence of copper ions, which is an essential condition of the invention, has a negative influence on the method for producing molding materials that undergo a heat processing process. . For example, polymethyl methacrylate resin obtained by the above method becomes strongly colored yellow or yellowish brown through the molding process, and cannot be used as a material that requires transparency and a beautiful appearance, such as the purpose of the present invention. do not have. Further, the residual CuS04 may be a problem depending on the purpose of use, for example, for food containers. In view of the above circumstances, the present inventors have conducted intensive research into a production method that meets the purpose of the present invention while taking advantage of the inherent advantages of emulsifier-free aqueous dispersion polymerization, and have arrived at the present invention.

The requirement is to maintain the polymerization temperature at 80 qo or higher, particularly at 8 qo or higher at the initial stage of polymerization. When the polymerization pressure is carried out under nitrogen, it varies depending on the sealing pressure, but in the case of methyl methacrylate, it exceeds the azeotropic temperature and becomes slightly pressurized. By employing such polymerization conditions, a sufficient polymerization rate can be obtained without using a polymerization promoter such as CuS04. The resulting polymer latex has an average particle diameter in the range of 0.3 to 0.7 mm, and has a fairly narrow particle distribution. Although the particle size is unusually large for an emulsion particle, the dispersion stability is sufficient, and no wall deposits or fly fly wing deposits are observed. Therefore, there is no limit to the concentration of the polymer latex obtained, but as an industrially advantageous condition, it is desirable that it be at least 2% by weight or more. The upper limit of the concentration range varies depending on the operating conditions, such as the monomer charging method, but if it is 45% by weight or less, deposits and agglomerates will not occur. The monomers to be polymerized consist of 50-10% by weight of methyl methacrylate and 0-5% by weight of one or more unsaturated monomers copolymerizable with methyl methacrylate. It is desirable that the unsaturated monomer has no adverse effect on the properties of the resulting methyl methacrylate resin.

Usually, the unsaturated monomer component copolymerizable with methyl methacrylate increases the various properties of methyl methacrylate resin, such as increasing fluidity when heated at molding temperature,
Alternatively, it is used to increase thermal stability or transparency. As copolymerizable unsaturated monomers suitable for these purposes, (meth)acrylic acid derivatives such as lower alkyl acrylate, lower alkyl methacrylate, cyanoethyl acrylate, acrylamide, acrylic acid, and methacrylic acid are preferred; in addition, styrene, Examples include monomers that can be copolymerized with methyl methacrylate, such as alkyl-substituted styrene, acrylonitrile, and methacrylonitrile, but depending on the monomer, the amount should be kept to an extent that does not impair transparency, which is the objective of the present invention. . In addition, one or more types of unsaturated monomers copolymerizable with these methyl methacrylates may be used, but the glass transition temperature of the hard resin itself should be at least 50 oo. . In the first stage polymerization to obtain an emulsion of this hard resin, it is important to adjust the degree of polymerization with a molecular weight regulator and to make the fluidity of the hard resin appropriate during molding. The viscosity average molecular weight is preferably in the range of 50,000 to 300,000.

The second point of the present invention is that, as mentioned above, the addition and polymerization of the elastomeric monomer is carried out in a step subsequent to the hard resin production step.

That is, the desired impact-resistant transparent resin is obtained by adding an elastomeric monomer stepwise in the presence of a hard polymer emulsion and polymerizing it. The above requirements are not simply a matter of operational conditions such as the order of addition of monomers;
It is essential.

That is, in the conventional methods for obtaining this type of resin material, which are called emulsion graft polymerization or bulk-suspension polymerization, it is necessary to form an elastomeric polymer first. The invention should be distinct in nature. Furthermore, under the conditions of the present invention, when the above order was reversed and the elastomeric polymer was formed first, it became cloudy. It has been experimentally revealed that only a resin with insufficient impact resistance can be obtained, which is completely different from the resin obtained by the present invention. Although the details of the polymerization mechanism, transparency, and impact resistance development mechanism in the present invention are not yet clear, it is possible that no emulsifier is present at the stage where the elastomeric monomer is added and converted into a polymer. In addition, the experimental fact that the coexisting hard polymer is contained in the emulsifier layer and no new particles are formed and no polymerization occurs in water indicates that the elastomer property is The ``field'' for monomer polymerization is limited within the hard polymer particles, and the size of the ``field'' has a diameter of 0.3 to 0.6 mm. It is thought that the present invention succeeded in combining the contradictory properties of high impact resistance and transparency using a relatively simple method.

The elastomeric monomer has a solubility in boiling water of 1.5% (
20qo) or less alkyl acrylate 50-9% by weight, [b} methyl methacrylate 3-4% by weight, 'c
'wt% of monomers with copolymerizable double bonds 0-4
, (d) 0.1 to 5% by weight of a copolymerizable monomer that is allyl, metaallyl, or crotyl ester of Q.8 monounsaturated carboxylic acid or dicarboxylic acid, {e} Crosslinking property of copolymerizable polyfunctionality A copolymer that is a monomer polymer consisting of 0 to 5% by weight of a monomer and exhibits a glass transition temperature (hereinafter referred to as Tg) of 25 qo or lower when the monomer mixture is copolymerized. It is a monomer mixture that gives

Here, Tg is the absorption maximum temperature of the dynamic elastic loss rate in the main dispersion region of the dynamic properties measured using a commercially available mechanical viscoelasticity measuring device. It is thought that at temperatures above this Tg, molecular motion becomes active and impact energy can be absorbed. As the alkyl acrylate having a water solubility (20q0) of 1.5% or less, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, etc. are used. The lower the Tg of these homopolymers, the more advantageous they are. The monomer having a copolymerizable double bond is the same as that used in the production of the hard resin-like component described above. Q.8 Allyl, metaallyl, or crotyl ester of monounsaturated carboxylic acid or dicarboxylic acid moderately crosslinks the elastomeric copolymer,
It is used to improve the mechanical properties and optical properties of the final resin, and is considered to be different from its action as a graft cross-agent, which is commonly proposed.

The allyl esters include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid, and particularly allyl acrylate and allyl methacrylate have a broken effect. The amount used ranges from 0.1 to 5%, preferably from 0.3 to 2% by weight of the total elastomeric monomer. If it is less than 0.1% by weight, not only will good impact resistance not be obtained, but the transparency of the final resin will be reduced.

On the other hand, if the amount used is too large than this range, not only will the impact resistance decrease, but the melt viscosity will become extremely high, resulting in a decrease in fluidity and making it unsuitable for hot molding. Copolymerizable polyfunctional monomers that can be used in combination include ethylene glycol dimethacrylate, 113-butylene glycol dimethacrylate,
1,4-butylene glycol dimethacrylate, propylene glycol dimethacrylate, etc. are preferred, and divinylbenzene, alkylene glycol diacrylate, etc. can also be used, but their effects are clearly distinguishable from the copolymerizable monomers that are essential components. .

Even if these polyfunctional monomers are not added at all, the desired composition can be obtained as long as the allyl ester is present, but it is preferable to add them when hot strength is strictly required. be.

The third important point of the present invention is that the elastomeric monomer {B} component further contains a small amount of methyl methacrylate.

According to the usual concept, the mixing of a component forming a hard polymer such as methyl methacrylate into the elastomer component increases the Tg of the elastomer component, which is disadvantageous to the development of impact resistance. However, in the method of the present invention, the presence of methyl methacrylate in the elastomer component is essential, and there is an upper limit to its amount. That is, there is an optimum range for the amount of methyl methacrylate in the elastomer component. FIG. 1 shows the relationship between the amount of methyl methacrylate in one component of the elastomer and the impact strength. Methyl methacrylate may be uniformly mixed with the elastomeric monomer component and copolymerized, but when the Tsukuda component is added in multiple parts, it is not necessary to distribute methyl methacrylate equally among all the parts. do not have. Rather, it may be preferable to carry out addition polymerization by changing the mixing amount for each division. That is, [
In the addition method in which the regular component is divided into several parts, it is better to distribute methyl methacrylate so that the mixing amount monotonically decreases or monotonically increases in the order of each division to improve the mechanical properties of the final resin.
Favorable for optical properties. The amount of methyl methacrylate incorporated into the elastomeric monomeric component should be limited so that the Tg of the elastomeric phase formed by polymerization of component 'B' is 25°C or less.

Otherwise, impact resistance near room temperature will not be developed. The amount usually used is 3-4% by weight of the total 'B' component. Furthermore, when impact resistance at lower temperatures is required, a range of 3 to 2% by weight is preferred. Polymerization of the elastomeric monomer [B-component] starts after the first stage of polymerization of the monomer mainly composed of methyl methacrylate is almost completed.

A small amount of polymerization initiator may also be added to the polymerization system to shorten the polymerization time. The ratio of the amount of elastomeric polymer to the amount of hard resin is adjusted depending on the desired physical properties.

Generally, as the proportion of the elastomeric polymer increases, the impact resistance increases, but the tensile strength, hardness, modulus, etc. decrease. Can be blended with other thermoplastics,
When used as a product as is, the content of the elastomeric polymer is in the range of 2 to 4% by weight, more preferably in the range of 15 to 35% by weight, based on the total resin. In addition, when producing a polymer by the method of the present invention for the purpose of using it as a modifier for other thermoplastic resins, the content of the elastomeric polymer is large, accounting for about 20 to 8% by weight of the total. . The polymer particles obtained in the form of an emulsion according to the present invention have a uniform particle size distribution within the range of 0.3 to 0.7 particles, and the emulsion is mixed with a dilute aqueous calcium chloride solution, a dilute aqueous magnesium chloride solution, etc. It can be easily recovered by salting, and it can also be recovered by spray drying. The resulting particulate or powdered polymer can be subjected to molding after over-drying in an oven, and can be extruded and injection molded.

Since the methyl methacrylate composite polymer obtained in the present invention does not contain emulsifiers or stabilizers, there is no deterioration in product quality such as coloring or water resistance due to these.

Further, to the obtained polymer composition, conventional light stabilizers, oxidation stabilizers, fillers, colorants, etc. can be added as necessary. The polymer composition obtained by the present invention has the impact resistance of other thermoplastic resins, generally thermoplastic resins having the same properties as the methyl methacrylate-based polymer used in the first step in producing the polymer of the present invention. Used as an additive for modification.

Normally, it is very difficult to blend sticky elastomers into rigid thermoplastic resins, but the polymer obtained in the present invention is not sticky even though it falls within the range of elastomers due to its composition, and the particles are not sticky. Since it does not coalesce even under normal processing conditions, it has the advantage of being easily and uniformly mixed with other thermoplastic resins, and can be suitable as a physical property modifier. The composite polymers of the present invention are optionally blended with other thermoplastic resins, and the amount of elastomer component in the blend composition depends on the type of elastomer, the type of thermoplastic resin, and the desired physical properties of the final blend composition. It varies greatly depending on the nature.

Generally, it is desirable to include at least 1.0% by weight of the elastomeric component in the molding composition for significant improvements in processability and physical properties. As the content of the elastomer component increases, physical properties such as modulus and hardness are adversely affected. Preferably the content of the elastomer component is in the range of 2 to 4% by weight, more preferably 15 to 3% by weight of the final formable (or aged) composition after blending.
It is in the range of 5% by weight. Blending of the composite polymer and thermoplastic resin of the present invention can be accomplished by any known method.

This is achieved, for example, by mulling in an extruder, roll mill or simulated apparatus. As mentioned above, the thermoplastic resin to be blended with the composite polymer is a methacrylic resin having the same composition as the hard resin produced in the first step of producing the composite polymer of the present invention, which has good physical and optical properties. It is also preferable from the point of view. The present invention will be specifically explained below with reference to examples, but the present invention is not limited by these examples. All parts are by weight unless otherwise indicated. In the examples, the abbreviations used are as follows.

Name Abbreviation Methyl methacrylate (MMA
) Butyl acrylate (BA) Ethyl acrylate (EA) Methiacrylate
(MA) Allyl methacrylate (
ALMA) Allyl acrylate (ALA
) Styrene (ST) Lauryl mercaptan (LM) Examples 1 to 3 250 ml of pure water was placed in a 5,000 ml three-necked flask equipped with a reflux condenser, a thermometer insertion tube, and a rubbing layer.
0 parts, 510 parts of MMA, 33 parts of MA, and 2.2 parts of LM were placed in the flask, and the mixture was kept under constant stirring (half-moon-shaped lampshade blade, length 6, 320 revolutions/min) under a stream of high-purity nitrogen.

The mixture was heated to 8.0°C in an oven, and 0.2 mol/3 parts of an aqueous potassium persulfate solution and 3 parts of a 0.2 mol/aqueous sodium thiosulfate solution were added at the same time. Polymerization started immediately and the system became cloudy. The temperature of the initial polymerization system is 85 to 90 qo.
After that, the polymerization was continued while maintaining the polymerization temperature at 82±2°C. Polymerization was completed in approximately 1 hour. According to exposure observation, the obtained emulsion consisted of particles of uniform particle size, and the average particle diameter was 0.351. The thermoplastic resin obtained by drying the emulsion has a low roform content of 0.
65, and was a methacrylic resin with good melt fluidity and suitable for thermoforming. A mixture of a predetermined amount of BA, 57 parts of MMA, 3.6 parts of MA, and a predetermined amount of ALA was added to the obtained emulsion system to continue polymerization.

Polymerization was completed in about 1 hour. Twenty-five minutes of a 1.5% aqueous calcium chloride solution was added to the system to carry out a coagulation, coagulation and solidification reaction under a heating lamp. A dry powder was obtained by filtering, washing with water, and drying. This was masticated for 200q0 for 5 minutes (Plastograph PL-300 model manufactured by Brabender) and 220q
A sheet was obtained by hot press molding at 0, and a sample for measurement of various physical properties was prepared. The molded product had excellent transparency with slight haze. The physical property measurement results are shown in Table 1.
Table 1 a) According to JIS-K-7113.

b) According to ASTM-D-256.

c) According to ASTM-D-1003.

As is clear from Table 1, according to the method of the present invention, although the refractive index of the hard resin phase and the elastomer phase (polybutyl acrylate) are different from each other, it has a considerable degree of transparency and It can be seen that a resin with excellent impact resistance can be obtained.

Comparative Example 1 The second stage polymerization was carried out in exactly the same manner as in Example 2, except that EA18 base, which is an alkyl acrylate with a solubility in water of 1.5% (20%) or more, was used instead of BA. .

Similarly, the Izod value at 25qo of the product obtained by post-treatment and molding was o. It was as low as 4ft·lb/in (notch). Comparative Example 2 In Example 1, first
BA18 Ikari Kaku, MM instead of MMA, MA, LM at stage
Using A57 part, MA3.6 part, AIA1/7 part, the second
MMA5 instead of BA, MMA, MA, AIA in the stage
Polymerization was carried out in exactly the same manner except that 10 parts of MA, 33 parts of MA, and 2.2 parts of LM were used.

The sheet obtained by press-molding the obtained polymer was milky white, opaque, and brittle, and the notched impact strength at 25 oo was 0.6 to 0.8 t·lb/inch.
Example 4 Polymerization was carried out in exactly the same manner as in Example 2 except that 30 parts of ST was further added to the elastomeric monomer component.

Table 2 shows the physical properties of a sheet obtained by press-molding the obtained polymer. Table 2 a), b), c) are the same as Table 1.

As is clear from the results in Table 2, BA in the elastomer phase
By using a copolymer of ST and ST to reduce the difference in refractive index with the hard resin phase, even better transparency than Examples 1 to 3 can be obtained.

Examples 5 and 6 According to the procedure of Example 1, in the first step, 850 parts of MMA, 138 parts of MA, and 3.6 parts of LM were polymerized to obtain an emulsion of thermoplastic methacrylic resin.

The average particle size was 0.42 mm. B to this emulsion
A314 section, MMA94 section, MA2 anchor section, ST5 anchor section,
A predetermined amount of the mixture was added in three portions. The distribution of each monomer into each division is as shown in the table below. The proportion of the elastomer component in the composite polymer is 3% by weight.

The obtained composite polymer was pelletized using a 40◇ extruder (L/D=28) (230 pm) and then injection molded (240 pm).
qo, 70k9/en) to obtain a physical property test piece. Furthermore, ALA
An example in which the formulation was used in an amount outside the range of the present invention is shown as a comparative example. The results are summarized in Table 3. Table 3 a), b), c) are the same as Table 1 K.

d) According to ASTM-D790K.

As is clear from Table 3, if the amount of ALA is less than 0.1% by weight of the elastomer component, not only high impact strength cannot be obtained, but also phase separation progresses over time, resulting in transparency.

(Comparative Example 3) On the other hand, if the amount is more than 5% by weight, the fluidity of the resin will be extremely poor and molding will not be possible. (Comparative Example 4) Moderate AL
With the amount of A, a resin with extremely excellent moldability, mechanical properties, and optical properties can be obtained. Example 7 According to the procedure of Example 1, in the first step, a predetermined amount of MMA,
PMMA was obtained by polymerizing a 0.4% by weight mixture of LM and MA.
An emulsion was obtained.

Next, 180 parts of BA and 33 parts of ST were added to this emulsion.
Part 6, ALAI. Polymerization was continued by adding a monomer mixture consisting of 7 parts of MMA and a predetermined amount of MMA. However, the total amount of MMA used in the first stage and the amount of MMA used in the second stage is 56
There are 7 parts. The obtained composite polymer was masticated and hot pressed according to the procedure of Example 1 to obtain a sheet. The Izod impact strength is shown in Figure 1. This shows that there is an optimal range for the amount of MMA used in the second stage in order to develop impact resistance. Examples 8 and 9 According to the procedure of Example 1, in the first step, 850 parts of MMA, 138 parts of MA, and 3.6 parts of LM were polymerized to obtain an emulsion of thermoplastic methacrylic resin.

The average particle size was 0.42 mm. B to this emulsion
A314 parts, MMA and MA specified amount, ST50 parts, AL
A monomeric mixture consisting of 2.8 parts of A was added in three portions. The distribution of each monomer to each division was made proportional to that in Examples 5 and 6. The obtained composite polymer was hot press molded according to the procedure of Example 1 to obtain a sheet, and its physical properties were measured. Comparative Examples 5 and 6 are shown in which the amount of MMA copolymerized in the elastomer component is outside the range defined by the present invention. The results are shown in Table 4. Table 4 a), b), c), d) are the same as Table 3.

As is clear from Table 4, when the amount of MMA copolymerized into the elastomer is less than 3% by weight, phase separation occurs and the elastomer becomes opaque.

(Comparative Example 5) On the other hand, when the amount exceeds 4% by weight, the balanced bonding property is not developed (Comparative Example 6). This example also proves that high room temperature impact resistance can be obtained within the range of 3 to 4% by weight. Comparative Example 7 In Example 1, in addition to the potassium persulfate-sodium thiosulfate system, 5 x 10-3 mol/6 parts of an aqueous copper sulfate solution was used as the initiator system, and polymerization was carried out at 70±2°C.

The reagent formulation is the same as in Example 6. The average particle size of the emulsion finally obtained was 0.20 mm. The physical properties of the injection molded product of the composition obtained by post-treatment and drying in the same manner were very similar to those of Example 6, but when molding over 24,000, an irritating odor was emitted and the molded product was colored yellow. did. Examples 10-12 According to the procedure of Example 1, first 453 parts of MMA, 7 parts of MA
Part 4, LMI. A first stage polymer emulsion was prepared by polymerizing the mixture.

Next, BA 288 parts, MMA 85 parts, MA 14 parts, ST4
8 parts and 2.8 parts of ALA were added in three parts. The method of distributing each monomer into three parts is as follows. The proportion of the elastomer component in the composite polymer thus obtained was 4% by weight.

This emulsion was combined with 850 parts of MMA, 138 parts of MA, and LM according to the first step thermoplastic resin manufacturing method of Example 1.
A blend composition was prepared by mixing in a predetermined ratio an emulsion of a methacrylic resin having a concentration of 0.63 methacrylic resin obtained by polymerizing 3.6 parts of a mixture.

The pellets were formed into pellets using a 40J extruder under the same conditions as in Examples 5 and 6, and the pellets were injection molded to obtain physical property test pieces. 5th result
Shown in the table.

Table 5 a), b). c) and d) are shown in Table 3. As is clear from Table 5, the composite polymer obtained according to the production method of the present invention is emulsion blended with an MMA-based hard resin to become an impact modifier, and the blended It can be seen that any desired impact resistance can be obtained depending on the amount.

Example 13 The dry powder of the composite polymer obtained in Examples 10 to 12 was mixed with a methacrylic resin pellet for injection molding (trade name: Parabet G, manufactured by Kyowa Gas Chemical Engineering K.K.) in an extruder. A blend composition was obtained by this, and this was injection molded to obtain a physical property test piece.

The measurement results for the test materials are shown in Table 6. Table 6 a), b). c) and d) are the same as in Table 3.

Comparing the results of this example with the results of Example 11 in Table 5, it can be seen that the extruder blend and the emulsion blend exhibit very similar impact resistance.

Examples 14-16 Following the procedure of Example 1, first MMA
227 copies, MA37 copies, LMI. The Ikarito mixture was polymerized to form a first stage polymer emulsion.

Next, a monomer mixture consisting of 360 parts of BA, 151 parts of MMA, 25 parts of MA, 60 parts of ST, and 5.5 parts of ALA was added to the emulsion in 8 portions and polymerized. The method of distributing each monomer into the eight divisions is as follows.

The proportion of the elastomer component in the composite polymer thus obtained was 69% by weight.

A blend composition was prepared by mixing the same MMA-MA emulsion used in Examples 10 to 12 with the emulsion obtained in this example at a predetermined ratio. This was formed into a pellet using a 400 extruder under the same conditions as in Examples 5 and 6, and injection molded to obtain a physical property test piece.The results shown in Table 7 were obtained. Table 7 a). b). c) and d) are the same as in Table 3.

Example 17 Using the press-formed sheet obtained in Example 9, ASTM
As a result of conducting a weather resistance test according to -E239, almost no deterioration in these physical properties was observed even after 300 hours of irradiation with a weather tester (xenon lamp XW-60V-3 manufactured by Shimadzu Corporation).

The results are shown in Table 8. Table 8 a). b). c) and d) are the same as in Table 3.

[Brief explanation of drawings]

FIG. 1 shows methyl methacrylate (MM
Relationship between the proportion (weight %) of A) (horizontal axis) and the impact strength (left vertical axis) of the composite polymer of the present invention finally obtained (curve shown by a solid line) and the elastomeric monomer Tg of the copolymer when the mixture is copolymerized (right vertical axis)
The relationship between the ratio (weight %) of MMA in the copolymer (horizontal axis) (force-v shown by the chain line) is shown. ★14

Claims (1)

[Claims] 1. An unsaturated monomer mixture consisting of 50 to 100% by weight of methyl methacrylate and 0 to 50% by weight of one or more unsaturated monomers copolymerizable with methyl methacrylate is combined with a molecular weight regulator and a persulfate to reduce the An emulsion of a rigid thermoplastic polymer (A) with a controlled molecular weight obtained by heterogeneously polymerizing in an aqueous medium at a polymerization temperature of 80° C. or higher in the presence of a redox catalyst consisting of a sulfoxy compound and without the presence of an emulsifier. and then in the emulsion (a) 50 to 90% by weight of alkyl acrylate having a solubility in water of 1.5% or less (20°C), (b) 3 to 40% by weight of methyl methacrylate, and (c) copolymerizable diamide. 0 to 40% by weight of a monomer having a double bond (d) 0.1 to 5% by weight of a copolymerizable monomer which is an allyl, metaallyl or crotyl ester of α/β-unsaturated carboxylic acid or dicarboxylic acid (e ) A monomer mixture consisting of 0 to 5% by weight of a copolymerizable polyfunctional crosslinking monomer, which exhibits a glass transition temperature of 25°C or lower when copolymerized. A method for producing a highly impact-resistant transparent methyl methacrylate resin, which comprises adding a monomer mixture (B) to form a copolymer in one or several stages and polymerizing without adding an emulsifier.