JPH08301937A - Production of methacrylic polymer - Google Patents

Abstract

PURPOSE: To produce a methacrylic polymer excellent in heat resistance by free radical-polymerizing a syrup prepared by dissolving an isotactic methyl methacrylate polymer in a monomer based on methyl methacrylate at a specified temperature in bulk. CONSTITUTION: A syrup is prepared by dissolving about 5-100 pts.wt. isotactic methyl methacrylate polymer under agitation in 100 pts.wt. 100 pts.wt. mixture of 50wt.% or above methyl methacrylate with a comonomer such as ethyl acrylate. 100 pts.wt. this syrup is mixed with about 0.001-1 pt.wt. polymerization initiator such as 2,2'-azobisisobutyronitrile in bulk, and the mixture is deaerated and poured into a cell composed of two glass plates spaced from each other to leave a definite gap. The mixture is radical-polymerized at 50 deg.C for a definite time and the formed product is heat-treated at about 100-130 deg.C and cooled to obtain a cast methyl methacrylate resin polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a methacrylic polymer containing a stereo complex having high heat resistance.

[0002]

BACKGROUND OF THE INVENTION A stereocomplex methacrylic polymer is a crystalline association consisting of an isotactic methyl methacrylate polymer and a syndiotactic methyl methacrylate polymer. As a method for obtaining this stereocomplex methacrylic polymer, a method of dissolving an isotactic methyl methacrylate polymer and a syndiotactic methyl methacrylate polymer in a solvent such as toluene, acetone, or dimethylformamide and mixing, There is a method of melt mixing both the polymers (Kobunshi Vol.41, December issue, 1992, published by Japan Society of Polymer Science 836-
843).

It can also be obtained by polymerizing methyl methacrylate in the presence of an isotactic methyl methacrylate polymer. For example, JOURNAL OF POLYMERS
CIENCE; PART A-1 VOL.10 1031-1049 (1972)) discloses a method of radically polymerizing a methyl methacrylate monomer in dimethylformamide in which an isotactic methyl methacrylate polymer is dissolved. .

The Journal of Polymer Science: Polymer Chemistry Edition (Journa
l of Polymer Science; Polymer Chemistry Edition, Vo
l.23,813-828 (1985)), an isotactic methyl methacrylate polymer is swollen with a methyl methacrylate monomer, and the methyl methacrylate monomer is radically polymerized in the isotactic methyl methacrylate polymer. Is described. The ratio of stereocomplexes among the polymers obtained by these methods is
Both are about 30%.

Japanese Unexamined Patent Publication No. 7-228617 discloses isotactic polymethyl methacrylate, methacrylic acid ester,
And a method for producing a methacrylic resin, which comprises polymerizing a polymerization liquid consisting of at least one selected from (meth) acrylic acid, acrylic acid ester and hydroxylalkyl (meth) acrylate in the presence of a radical polymerization initiator. It is disclosed. Further, Japanese Patent Application Laid-Open No. 7-242705 discloses a method of suspension-polymerizing a polymerization liquid obtained by anionic polymerization of a methyl methacrylate monomer using a Grignard reagent as an initiator in water.

The use of the stereocomplex methacrylic polymer is described, for example, in JP-B-47-14834.
A laminated safety glass is disclosed in which a gel transition composition of an isotactic methyl methacrylate polymer and a syndiotactic methyl methacrylate polymer is introduced into an intermediate layer and polymerized, which is introduced into the intermediate layer. Also,
JP-A-64-14216 discloses a stereocomplex methacrylic polymer derived from a mixture of isotactic methyl methacrylate polymer and syndiotactic methyl methacrylate polymer, which has low hygroscopicity and is suitable for optical materials. A water resistant material is disclosed.

[0007]

Among the methods for obtaining the above-mentioned stereocomplex methacrylic polymer, a method for preparing an isotactic methyl methacrylate polymer and a syndiotactic methyl methacrylate polymer which are separately synthesized in advance is as follows. Both polymers have low productivity, are not suitable for mass production, and require many steps.

In the method disclosed in Japanese Patent Laid-Open No. 7-228617, the polymerization temperature is set to 200 ° C. or lower, preferably 40 to 150 ° C.
Conducted at 5 ° C. However, at this temperature, the polymerization temperature in the first stage is too high, and almost no stereocomplex is formed in the resulting polymer. According to the method of Japanese Patent Application Laid-Open No. 7-228617, the temperature of suspension polymerization in the examples is 75 ° C., a stereo complex is hardly formed in the resulting polymer, and a simple isotactic methyl methacrylate polymer and syndiotactic polymer are produced. Only a mixture of tic methyl methacrylate polymers is obtained.

Further, the polymerization in the presence of the isotactic methyl methacrylate polymer in the above-mentioned solvent becomes complicated by the use of the solvent in a wide variety of steps.
The method of radically polymerizing the methyl methacrylate monomer in the asotactic methyl methacrylate polymer is only a laboratory method because the amount of the methyl methacrylate monomer to be polymerized is limited.

In view of such circumstances, the present inventor has diligently studied a method for producing a methacrylic polymer containing a stereocomplex, and as a result, as a result, a monomer containing methyl methacrylate as a main component is replaced with isotactic methacrylic acid. By radical polymerization of a syrup in which a methyl acid polymer is dissolved in a non-solvent at a relatively low temperature, methyl methacrylate having high productivity and easy stereocomplex content similar to that of the conventional method can be obtained. The inventors have found that a resin based resin can be produced and have reached the present invention.

[0011]

[Means for Solving the Problems] That is, according to the present invention, a syrup in which an isotactic methyl methacrylate polymer is dissolved in a monomer containing methyl methacrylate as a main component in a non-solvent at 50 ° C. or lower. Is a method for producing a methacrylic polymer, which is characterized by radically polymerizing.

The monomer containing methyl methacrylate as a main component in the present invention is a monomer mixture containing 50% or more of methyl methacrylate and optionally other copolymerizable monomer. Examples of other copolymerizable monomers include methacrylic acid such as ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate. Acrylic esters such as esters, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, methacrylic acid, It is a monofunctional monomer such as unsaturated acids such as acrylic acid, styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide. Furthermore, (poly) alkylene glycol di (meth) acrylic acid ester, allyl (meth) acrylic acid ester, trimethylolpropane tri (meth) acrylic acid ester, divinylbenzene, etc., having two or more unsaturated double bonds in the molecule. It is another functional monomer.

In the present invention, an isotactic methyl methacrylate polymer which is dissolved in a monomer containing methyl methacrylate as a main component means that the isotacticity of the methyl methacrylate unit chain is 50% or more in terms of triad. A certain polymer, which is a homopolymer of a methyl methacrylate unit and a copolymer containing the above-mentioned other copolymerizable monomer unit. The isotactic methyl methacrylate-based polymer is anionically polymerized using a known method, for example, a Grignard reagent as disclosed in JP-A-61-179210 and JP-A-61-176617 as a polymerization initiator. It is obtained by

A syrup in which the isotactic methyl methacrylate-based polymer is dissolved in a monomer whose main component is methyl methacrylate means that the isotactic methyl methacrylate-based polymer is completely dissolved in the monomer. It was dissolved in. In order to obtain the syrup, the isotactic methyl methacrylate polymer may be prepared in advance and dissolved in the monomer. For this purpose, it is preferable that the temperature is higher than room temperature and the temperature is higher.

The amount ratio of the monomer to the isotactic methyl methacrylate polymer is not particularly limited as long as the isotactic methyl methacrylate polymer is completely dissolved. 5 to 100 parts by weight of the isotactic methyl methacrylate-based weight body is preferable per part by weight.

If necessary, known additives such as antioxidants, UV absorbers, chain transfer agents, mold release agents, dyes, pigments and inorganic fillers are added to the syrup thus obtained. It can also be added.

The radical polymerization of the syrup in a non-solvent is a radical polymerization method which does not use a solvent for dissolving the monomer or the polymer, and if the solvent is not used, a known methacrylic polymer is used. The manufacturing method of the coalescence can be applied as it is.
Specifically, it is a suspension polymerization method, a bulk polymerization method, or the like.

The polymerization initiator for carrying out the radical polymerization of the present invention may be one known for the polymerization of methyl methacrylate monomer. For example, for thermal polymerization, organic peroxide type initiators such as benzoyl peroxide, di-t-butyl peroxide, t-butyl peroxy 2-ethyl hexaate; 2,2'azobisisobutyronitrile, 2,
Azo initiators such as 2'azobis (2,4-dimethylvaleronitrile); further known redox initiators obtained by combining a peroxide initiator and a reducing compound such as amines and mercaptans as main components. Etc. For photopolymerization, benzoin, benzoin ethers, 1
-Hydrohexyl phenyl ketone, benzyl dimethyl ketal, acylphosphenoxide, benzophenone,
Michler's ketone, thioxanthone, etc., and, if necessary, a photosensitizer are used in combination. The amount of these initiators to be used is 0. 0 based on 100 parts by weight of the syrup.
It is about 001 to 1 part by weight. This amount may be a known appropriate amount depending on the polymerization method. That is, in the suspension polymerization method, 0.0
5 to 0.5 parts by weight, 0.001 in the bulk polymerization method
It is about 0.1 part by weight.

For example, the suspension polymerization method is a method in which the syrup containing the above-mentioned polymerization initiator is suspended in an aqueous medium in which a suspension stabilizer is present, and polymerization is carried out. The ratio of the aqueous medium to the syrup is 1: 1 to 10: 1, preferably 1 :.
It is in the range of 1 to 4: 1. The suspension stabilizer may be a known one, and examples thereof include polyacrylic acid and its alkali salt, polymethacrylic acid and its alkali salt, sodium methacrylate-alkyl methacrylate copolymer, and the like. Or they can be used together.

The bulk polymerization method is a so-called mold.
This is a casting polymerization method in which the syrup containing the above-mentioned polymerization initiator is injected to carry out thermal polymerization or photopolymerization, and a molded product having a desired shape is obtained with the completion of the polymerization. As the mold, for example, in the case of a plate as a molded body, a batch type cell casting method using two glass plates or a metal plate, a cell composed of a soft sealant and a clamp, and two stainless steel plates. There is a continuous cell with a continuous belt.

The heating-removing method and the conditions thereof in the thermal polymerization may be based on a known method, for example, a known method using warm air, warm water or the like. As a light irradiation method for performing photopolymerization, visible light, ultraviolet rays or the like may be irradiated with a high pressure mercury lamp, a metal halide lamp, a low wavelength UV lamp, a xenon lamp, a crypto arc lamp, a xenon flash lamp, a flash UV lamp or the like.
These methods and conditions may also be based on known methods.

The polymerization is carried out at 50 ° C. or lower, preferably 40 ° C. or lower. When the temperature is higher than 50 ° C, a stereo complex is not formed, which is not preferable. After the polymerization for a predetermined time, heat treatment is performed to reduce the amount of residual monomers as much as possible. The heat treatment is 100 to 130 ° C., preferably 11
It is performed at 0 to 125 ° C. or lower. If the temperature is lower than 100 ° C., the amount of residual monomers is not so small, and if the temperature is higher than 130 ° C., depolymerization proceeds, the amount of residual monomers increases, and the heat resistance decreases, which is not preferable. In addition, when a comonomer such as methyl acrylate is added as a monomer in addition to methyl methacrylate and polymerized, depolymerization is suppressed even if the heat treatment is performed at about 140 ° C. Absent. Polymerization is carried out at 50 ° C. or below, then 100-130
A methacrylic polymer containing a stereo complex can be obtained even by heat treatment at ℃. This is probably because the polymerization is almost carried out under the condition that the stereocomplex is formed, so that the degree of freedom of the molecule is limited even if the temperature is raised thereafter, and the stereocomplex is not decomposed.

[0023]

According to the present invention, if only an isotactic methyl methacrylate polymer is prepared in advance, a known method for polymerizing an ordinary syrup containing methyl methacrylate as a main component, that is, a special catalyst is used. A methacrylic polymer can be obtained with good productivity and ease without using a system or a solvent, and in which the content of the stereocomplex is equivalent. The polymer obtained according to the present invention has high heat resistance while maintaining the transparency and light transmittance that the methacrylic polymer originally has. Therefore, it can be preferably used in a place where the temperature becomes high in the presence of a light source or in a place where the temperature further rises in the surrounding environment.

[0024]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to this. The physical property measurements and test methods used in the examples are as follows. (1) Number average molecular weight: measured using gel permeation chromatography (150-CV manufactured by Waters Co.) using tetrahydrofuran as a solvent. A polystyrene standard calibration curve was used for molecular weight determination. (2) Isotacticity: It was measured using a proton nuclear magnetic resonance spectrum analyzer (XL-200 manufactured by Varian) using nitrobenzene-d5 as a solvent. The isotacticity indication is a triad indication (mm). (3) Content of stereocomplex in methacrylic polymer: Makromolekula
re Chemie) Vol 184 (1983) 2679-2691 Among them, it was measured and calculated based on the description in Table 1 of Column 5. First, the differential scanning calorific value of the sample polymer was measured by using a differential scanning calorimeter (DSC20 manufactured by Seiko Denshi Kogyo Co., Ltd.) at a heating rate of 10 ° C.
/ Min, the melting point at the apex of the endothermic peak, the integral value of the endothermic peak to obtain the change in heat of fusion, the change in heat of fusion of the stereocomplex methyl methacrylate polymer described in the literature, 58 J / g The stereocomplex content was determined from the ratio. (4) Heat resistance: The Vicat softening point was measured according to JIS K 7206.

EXAMPLE 1 Powder 18 of isotactic methyl methacrylate polymer (number average molecular weight 24,500, isotacticity 96.6%) obtained by anionic polymerization was added to 100 parts by weight of methyl methacrylate monomer. One part by weight was added with stirring, and stirring was continued at 60 ° C. for 1 hour to dissolve the isotactic methyl methacrylate polymer. This was cooled to room temperature to obtain a syrup in which an isotactic methyl methacrylate polymer was dissolved. 0.39 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) was added to 99.7 parts by weight of this syrup, dissolved and deaerated, and then with two glass plates and a vinyl chloride resin gasket. Then, the mixture was poured into a cell configured so that the gap between the glass plates was 3 mm, and polymerization was carried out at 30 ° C. for 40 hours. Further, it was subjected to heat treatment in a hot air drying oven at 120 ° C. for 2 hours, cooled to around room temperature, and then the glass plate was removed to obtain a methyl methacrylate resin cast polymer having a thickness of 3 mm. The cast polymer obtained was evaluated. Table 2 shows the results.

Comparative Example 1 Cast polymerization was carried out in the same manner as in Example 1 except that the isotactic methyl methacrylate polymer was not added to obtain a cast polymer. The cast polymer obtained was evaluated. Table 2 shows the results.

Example 2 Cast polymerization was carried out in the same manner as in Example 1 except that the number average molecular weight of the isotactic methyl methacrylate polymer obtained by anionic polymerization was 14,800. Obtained. The cast polymer obtained was evaluated. Table 2 shows the results.

Example 3 90 parts by weight of methyl methacrylate monomer, 10 parts by weight of isotactic methyl methacrylate polymer obtained by anionic polymerization (number average molecular weight 32,900, isotacticity 97.8%). Parts, and except that the polymerization was carried out at 30 ° C. for 16 hours, a cast polymer was obtained in the same manner as in Example 1. The cast polymer obtained was evaluated. Table 2 shows the results.

Examples 4 to 5 and Comparative Examples 2 to 3 Cast polymers were obtained in the same manner as in Example 3 except that the amount of polymerization initiator, the polymerization temperature and the polymerization time were changed as shown in Table 1. . The cast polymer obtained was evaluated. Table 2 shows the results.

Example 6 Powder of 89.5 parts by weight of methyl methacrylate monomer, isotactic methyl methacrylate polymer (number average molecular weight 32,900, isotacticity 97.8%) obtained by anionic polymerization. A cast polymer was obtained in the same manner as in Example 3 except that the amount was 10 parts by weight and 0.5 part by weight of the methyl acrylate monomer was added. The cast polymer obtained was evaluated. The results are shown in Table 1.

Examples 7 to 8 and Comparative Examples 4 to 5 Cast polymers were obtained in the same manner as in Example 6 except that the amount of polymerization initiator, the polymerization temperature and the polymerization time were changed as shown in Table 1. . The cast polymer obtained was evaluated. Table 2 shows the results.

[0032]

[Table 1] MMA: Methyl Methacrylate Monomer it-PMMA: Isotactic Methyl Methacrylate Polymer MA: Methyl Acrylate Monomer (*): Same Isotactic Methyl Methacrylate Polymer as in Example 3

[0033]

[Table 2] SC body: Stereo complex body

Claims (4)

[Claims] 1. A methacrylic compound characterized in that a syrup in which an isotactic methyl methacrylate polymer is dissolved in a monomer containing methyl methacrylate as a main component is radically polymerized at 50 ° C. or lower in a non-solvent. Of producing a base polymer. 2. The method for producing a methacrylic polymer according to claim 1, wherein the syrup polymerization is cast polymerization. 3. After radical polymerization at 50 ° C. or lower, 1
The heat treatment is performed at 00 to 130 ° C.
A method for producing the methacrylic polymer described above. 4. The method for producing a methacrylic polymer according to claim 1, wherein the monomer containing methyl methacrylate as a main component is a monomer mixture containing methyl methacrylate as a main component and an acrylate ester. .