JPH0460126B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a method for producing a novel thermoplastic polymer having excellent heat resistance and transparency. "Technical background of the invention and its problems" Transparent vinyl polymerized thermoplastic resins such as polymethyl methacrylate and polystyrene are widely used in home appliances, vehicle optical parts, instrument panels, lighting window materials, etc. In recent years, these resins have come to be used for special purposes such as materials for optical fibers.There is a strong demand for these resins to have increased heat resistance. As a method for improving heat resistance, a method has been proposed in which a maleic anhydride structure is introduced into the main chain of the polymer, as described in JP-A-55-102614 and JP-A-57-153008. It increases heat resistance by forming a ring structure and imparting rigidity to the divinyl monomer.Maleic anhydride has copolymerization properties that are quite different from other divinyl monomers, and it improves its copolymerizability. It is known that a good method is to use styrene as a copolymerization monomer.In this case, the maleic anhydride/styrenic copolymer has five-membered rings of maleic anhydride in the polymer chain. Heat resistance is improved by forming a structure. Examples of such polymers include methyl methacrylate/maleic anhydride/styrene ternary copolymers, and these ternary copolymers copolymerized with other vinyl monomers. There are quaternary copolymers. However, since these polymers are multicomponent copolymers, they not only are difficult to manufacture, but also have the problem that the resulting polymers do not necessarily have good transparency. A method for obtaining a polymer that is easy to produce and has excellent heat resistance and transparency is a method in which a glutaric anhydride ring structure obtained by thermally decomposing a polymethacrylic acid polymer is formed in the polymer main chain. What is referred to here as glutaric anhydride is usually acrylic acid or methacrylic acid in a polymer (hereinafter, "acrylic acid or methacrylic acid" is simply referred to as "(meth)acrylic acid"). }Means (meth)acrylic anhydride obtained by dehydration reaction between units. Regarding such polymer side chain reactions, PH
Polymer 1 125 by Grant and N. Grassie
(1960). According to the description,
When polymethacrylic acid is thermally decomposed at 200°C, a six-membered glutaric anhydride ring structure is generated in the polymer main chain, and at the same time a condensation reaction occurs between the polymers to obtain a crosslinkable polymer. However, since this polymer has intermolecular crosslinks, it does not dissolve or melt in a solvent. In other words, the resins obtained by these methods are
It did not have thermoplasticity and had poor workability. As described above, in polymer side chain reactions, reactions occur not only between segments but also between polymers, and a crosslinkable polymer is usually obtained. In fact, heat-resistant decomposition-resistant industrial products obtained using conventional polymer side chain reactions have been limited to insoluble crosslinkable polymers. [Object of the Invention] An object of the present invention is to provide a manufacturing method that can easily obtain a polymer having thermoplasticity, transparency, heat resistance, and heat decomposition resistance. [Summary of the Invention] The present inventors have obtained a transparent polymer having an acid anhydride structure in the molecule and no intermolecular crosslinking structure, and having good heat resistance, heat decomposition resistance, and shaping processability. After careful study, we found that the side chain reactive groups of the polymer react between intramolecular segments, suppressing the disadvantageous crosslinking reaction described above, and containing a six-membered glutaric anhydride ring structure in the main chain, resulting in a crosslinked structure. The present invention was completed based on the discovery that a thermoplastic polymer with excellent heat resistance, which is virtually non-existent, can be obtained. That is, 5% by weight or more of the thermoplastic polymer tert-butyl acrylate or tert-butyl methacrylate of the present invention, and at least one ethylenic monomer selected from the group consisting of acrylic esters, methacrylic esters, and styrene. A polymer obtained by copolymerizing a mixture consisting of % by weight or less,
This is a method for producing a thermoplastic polymer with excellent heat resistance, which is characterized by thermal decomposition at 200 to 450°C. The tert-butyl (meth)acrylate structural unit in the raw material polymer used in the present invention is an essential component for forming a glutaric anhydride ring within the molecule without forming intermolecular crosslinks. That is, the tert-butyl (meth)acrylate structural unit in the raw material polymer easily generates and eliminates isobutene by heat treatment, and undergoes a condensation reaction to form (meth)acrylic anhydride rings between intramolecular segments. form. In addition, when the adjacent group is a (meth)acrylic acid ester segment, a condensation reaction occurs between the tert-butyl (meth)acrylate structural unit and the (meth)acrylic acid ester segment,
A (meth)acrylic anhydride ring is formed in the main chain. Surprisingly, in the polymer side chain reaction that produces glutaric anhydride rings as described above, a non-crosslinked polymer is produced without a condensation reaction of the polymer rings, resulting in a solvent-soluble polymer. And a meltable polymer is obtained. The reason for this result is not clear, but
This is thought to be because the intramolecular inter-segment condensation reaction proceeds efficiently and preferentially due to thermal decomposition of the tert-butyl (meth)acrylate segment in the polymer. Another reason for using a polymer containing tert-butyl (meth)acrylate as a raw material in the present invention is that in the tert-butyl ester, the hydrogen atoms of the butyl group form a six-membered ring structure between the carbonyl oxygen atoms. This means that hydrogen is easily extracted, and furthermore, considering the free rotation of the C--O bond and the C--C bond, the probability that a hydrogen atom exists near the carbonyl oxygen is highest. For example, n-butyl methacrylate, iso-
Examples include butyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, and the like. However, although these esters have a hydrogen atom near the carbonyl oxygen, the probability that the hydrogen atom exists near the galvonyl oxygen is tert-
Lower than butyl (meth)acrylate. Therefore, in the thermal decomposition reaction, the rate of production of the methacrylic acid segment intermediate is much slower than that of tert-butyl (meth)acrylate. Therefore, in cases other than tert-butyl (meth)acrylate, the thermal decomposition reaction time is longer, and
The thermal decomposition temperature also increases. As the tert-butyl (meth)acrylate monomer, tert-butyl methacrylate is preferred. When a polymer containing tert-butyl methacrylate is thermally decomposed, the tert-butyl methacrylate segment very easily decomposes its side chain to generate and eliminate isobutene, which forms methacrylic anhydride through a condensation reaction, resulting in heat-resistant properties. A new thermoplastic polymer with excellent properties can be obtained. The content of tert-butyl (meth)acrylate monomer in the raw material polymer is 5% by weight or more. This is because if the content is less than 5% by weight, a thermoplastic polymer with excellent heat resistance cannot be obtained. The raw material polymer used in the present invention contains at least one ethylenic monomer selected from the group consisting of styrene, substituted styrenes such as chlorostyrene, acrylic esters, and methacrylic esters. Acrylic ester or methacrylic ester (hereinafter referred to as (meth)acrylic ester)
Examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, ) acrylates and alkyl (meth)acrylates containing aliphatic or aromatic functional groups having 1 to 18 carbon atoms, such as fluorinated alkyl (meth)acrylates. However, it is preferable that the obtained polymer be one that is difficult to be colored by heating and one that does not form an intermolecular crosslinked structure, and from this point of view, the remaining components to be introduced into the raw material polymer used in the present invention are Preferred are methacrylic monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, and fluorinated alkyl methacrylate, with methyl methacrylate being particularly preferred. As described above, the polymer containing tert-butyl methacrylate undergoes a thermal decomposition reaction easily, exhibits good copolymerizability with methacrylic acid ester, and easily forms a glutaric anhydride ring structure. Polymerization catalysts used to obtain the raw material polymer according to the present invention include ordinary radical polymerization initiators,
For example, di-tert-butyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, tert-butyl perphthalate, tert-butyl perbenzoate, methyl isobutyl ketone peroxide, lauroyl peroxide, cyclohexyl peroxide, 2,5-dimethyl-2,5-
Organic peroxides such as di-tert-butylperoxyhexane, tert-butylperoctanoate, tert-butylperisobutyrate, tert-butylperoxyisopropyl carbonate, methyl-2,
2'-azobisisobutyrate, 1,1'-azobiscyclohexanecarbonyltrile, 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, 2-carbamoyl-azobisisobutyronitrile), 2, Examples include azo compounds such as 2'-azobis(2,4-dimethylvaleronitrile) and 2,2'-azobisisobutyronitrile. Further, the chain transfer agent used for producing the raw material polymer is not particularly limited, and a conventional degree of polymerization regulator may be used. For example, alkylcaptan, carbon tetrachloride,
Examples include carbon tetrabromide, dimethylacetamide, dimethylformamide, and triethylamine, among which alkylmercaptan is most preferred. In the case of free radical initiation, examples of the polymerization method include emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization, but other production methods can be employed depending on the purpose. Further, a Gourigniard reagent polymerization initiation catalyst, an alkyl lithium-based ionic polymerization catalyst, etc. can be used. The thermal decomposition temperature of these raw material polymers is 200 to 450.
The temperature is preferably 0.degree. C., and the heat treatment is preferably performed in an atmosphere of an inert gas such as nitrogen or argon in order to prevent abnormal reactions from occurring. The polymer of the present invention obtained in this way contains a glutaric anhydride ring structural unit, and in some cases, a tert-butyl (meth)acrylate structural unit that is an unreacted raw material segment or an intermediate segment. (meth)acrylic acid structural units. A simple method for analyzing the presence or absence of a crosslinked structure in the obtained polymer is to measure the melt fluidity of the polymer, or to check the solubility in a solvent such as dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, methyl ethyl ketone, etc. Furthermore, the presence or absence of a crosslinked structure in the polymer can be confirmed by measuring undissolved particles in the polymer solution using an optical or physical method. As an optical method, for example, there is a light scattering method, and as a physical method, there is a method of observing changes in solution concentration using a centrifuge. It is also possible to separate the crosslinkable polymer in a gel state by centrifugation. Moreover, it is preferable that the polymer obtained by the present invention has an intrinsic viscosity of 0.01 to 2 dl/gr. If the intrinsic viscosity is less than 0.01 dl/gr, the polymer will lack mechanical strength, making it difficult to use in practice. Moreover, if it exceeds 2 dl/gr, the viscosity becomes too large, which may cause problems in shaping properties such as melt molding. In particular, when used as a molding material, the intrinsic viscosity of this polymer is preferably 0.1 to 1 dl/gr. In addition, in this specification, the intrinsic viscosity of the polymer is
The flow time (ts) of a dimethylformamide solution with a sample polymer concentration of 0.5% by weight and the flow time (to) of dimethylformamide were measured using a Deereax-Bischoff viscometer at a temperature of 25 ± 0.1°C.
The relative viscosity of the polymer ηrel is determined from the ts/to value.
This is the value calculated from the following formula. ηinh=(lnηrel)/c (In the formula, c represents the number of grams of polymer per 100 ml of solvent.) [Effects of the Invention] The thermoplastic polymer of the present invention is superior to comparable vinyl polymers of the same type. Although the heat resistance temperature has been improved by 5 to 10°C or more, and the heat decomposition resistance has been improved, its transparency, hot melt flowability, and solubility in various solvents are good. Therefore, the polymer obtained according to the present invention can be used as various molding materials, coating materials, resist materials, optical materials, heat-resistant films, fiber materials, and the like. When this polymer is used in combination with a crosslinking agent such as a low molecular weight polyamine, it can be made into a resin composition exhibiting crosslinking and curable properties. Furthermore, a polymer having a glutarimide ring structure can be obtained by subjecting the thermoplastic polymer obtained according to the present invention to a heat reaction with ammonia or a reagent capable of generating ammonia. Note that examples of reagents having ammonia-generating ability include urea, substituted urea, formamide, and ammonia aqueous solution. Further, by reacting with a primary amine such as methylamine, ethylamine, or aniline, a polymer having an N-alkyl-substituted glutarimide ring structure can be obtained. [Examples of the Invention] The present invention will be described in more detail below with reference to Examples. In these Examples, the following method was used to measure the properties of the polymer. The infrared absorption spectrum was measured using an infrared spectrophotometer (Co., Ltd.).
It was measured by the KBr disc method using a Hitachi Model 285). Number average molecular weight (Mn), weight average molecular weight (Mw)
and Z average molecular weight (Mz) are gel permeation chromatography HLC-manufactured by Toyo Soda Co., Ltd.
Using 802UR, the sample concentration was 0.1% (weight/volume), the elution solvent was dimethylformamide, and the flow rate was 1.2ml/
The measurement was performed in minutes, and a monodisperse polystyrene calibration curve was used as the calibration curve. The heat resistance test was carried out in accordance with ASTM-D-1525 using a Vikatsu softening point measuring device (manufactured by Toyo Seiki Seisakusho) at a heating rate of 50±50° C./hr and using sample pieces of 5×10×10 mm. Storage modulus (E′) and loss modulus (E″) were measured using a dynamic viscoelasticity measurement device (manufactured by Toyo Baldowin Co., Ltd.) at a heating rate of 2°C/min at 110Hz.For measurement of glass transition temperature A differential scanning calorimeter (PERKIN-ELMER DSC-2C model) was used.Thermal decomposition resistance was measured by thermogravimetric analysis (TGA).
(PERKIN-ELMER TGS-1 type). A simple method for the solubility test was to visually test the solubility in a specific solvent. At the same time, by centrifugation method (Kubota Manufacturing Co., Ltd. KH-180 centrifuge)
Solubility was evaluated based on the presence or absence of gel fraction after centrifugation at rotation/min for 60 minutes. In addition, "parts" described below shall represent parts by weight. Example 1 50 parts of methyl methacrylate, 50 parts of tert-butyl methacrylate, 0.01 part of 2,2'-azobisisobutyronitrile and 0.1 part of tert-dodecyl mercaptan.
The sample was melted and placed in a glass ampoule, cooled under liquid nitrogen temperature, degassed repeatedly, and sealed in a nitrogen atmosphere. Next, this sealed ampoule was placed in a heating bath and heated at 70°C for 15 hours, and then further heated at 120°C.
The polymerization was completed by heating at ℃ for 3 hours. The reaction conversion rate of monomers in this polymerization was 95%. Next, the resulting polymer was dissolved in tetrahydrofuran and then poured into n-hexane for precipitation, which was repeated several times to purify the polymer. The purified polymer had the following physical properties. Number average molecular weight (Mn); 8.61×10 ⁴ Weight average molecular weight (Mw); 20.9×10 ⁴ Z average molecular weight (Mz); 32.0×10 ⁴ Mw/Mn=2.44, Mz/Mn=3.72 Intrinsic viscosity; 0.35 dl/ gr Further, the results of measuring the infrared absorption spectrum of this polymer are shown in FIG. Absorption based on the stretching vibration of the ester carbonyl was measured at a wave number of 1720 cm ^-1 . Next, this polymer was placed in a glass tube and subjected to a thermal decomposition reaction at 230° C. for 5 hours in an oil bath under a nitrogen atmosphere. In this reaction, isobutene was produced as a volatile organic gas, and methanol and water were also produced. 1 hour after reaction, 1.0mm
Volatile components were removed under reduced pressure of Hg to obtain a foamed white resin body. Next, this resin body was crushed.
This pulverized polymer had the following physical properties. Number average molecular weight (Mn); 8.22×10 ⁴ Weight average molecular weight (Mw); 17.6×10 ⁴ Z average molecular weight (Mz); 28×10 ⁴ Mw/Mn=2.34, Mz/Mn=3.51 Intrinsic viscosity; 0.32 dl/ gr dimethylformamide 10 of this polymer (weight/
When dissolved as a solution (volume)%, it was visually determined that the solution was uniformly dissolved. Apply this solution 15,000 times/
When the presence or absence of gel components in the precipitated portion was confirmed by centrifugation for 1 minute, the solution was homogeneous and no gel components were present. In addition, this polymer was heated at 250℃ and 150℃.
A film with a thickness of 150 μm was prepared by heat-pressing molding at Kg/cm ² and its dynamic viscoelasticity was measured. The dispersion peak of the loss modulus (E'') was 146°C. A flat plate of 10 x 10 x 5 mm (thickness) was prepared in the same manner and the Vikato softening point was measured, and it showed a value of 151°C. Furthermore, the glass transition temperature determined using a differential operation calorimeter was between 123 and 154°C. Furthermore, the infrared absorption spectrum of the above molded film was measured. The results are shown in Figure 2. As can be seen from Figure 2, in addition to the absorption of the stretching vibration of ester carbonyl at a wave number of 1720 cm ^-1 , there are also absorptions at wave numbers of 1756 cm ^-1 and 1802.
Absorption of acid anhydride carbonyl stretching vibration due to the formation of glutaric anhydride group at cm ^-1 was confirmed. Next, this polymer was extruded using a Tortoindexer (Toyo Seiki Seisakusho) at 230℃ under a load of 10 kg, and a good strand-shaped resin body was obtained.
It showed an MI value of 5.8gr/10min. The molecular weight and molecular weight distribution of the starting material, tert-butyl methacrylate/methyl methacrylate copolymer, and the molecular weight and molecular weight distribution of the polymer obtained by heat-treating this raw material polymer were measured by gel permeation chromatography ( GPC)
When the polymer was measured and compared, it was observed that the apparent molecular weight of the polymer decreased due to dealfination, dehydration, and dealcoholization accompanying thermal decomposition, and slight decomposition of polymer chains at the initial stage of thermal decomposition. .
However, no increase in molecular weight due to intermolecular cross-linking reaction, no widening of molecular weight distribution, no significant decrease in molecular weight due to main chain scission, and no significant change in molecular weight distribution were observed. This polymer was processed using a 25φ vented extruder (Daiichi Jitsugyo Co., Ltd.).
After extrusion molding, the pellets were pelletized using a full-flight screw L/D=24, manufactured by Komatsu, Ltd., die temperature: 230°C, adapter temperature: 230°C, screw barrel temperature: 200-230°C. Using this pelletized polymer, a flat plate (60 mm) was molded using a 1 oz.
x 80 x 2 mm) was obtained. Regarding the obtained resin molded plate, ASTM D-
1003, the total light transmittance was 90% and the haze value was 4.5. Table 1 shows the main physical properties obtained. Examples 2 to 5 Raw material polymers were prepared by repeating the same operations as in Example 1 using monomer compositions as shown in Table 1, and were heat-treated to obtain polymers. Table 1 shows the results of measuring its physical properties. Examples 6-8 50 parts of methyl methacrylate, 50 parts of tert-butyl methacrylate, 0.01 part of 2,2'-azobisisobutyronitrile and 0.1 part of tert-dodecyl mercaptan
Example 1
A polymer was prepared in the same manner as above, and a purified polymer was obtained. This polymer was subjected to a thermal decomposition reaction at 230° C. for 30 minutes in an oil bath in the same manner as in Example 1. The reaction conversion rate of this thermally decomposed product was confirmed to be 30% based on the absorption amount of acid anhydride carbonyl in the infrared absorption spectrum. Further, thermal decomposition treatment was performed, and the physical properties of the resulting polymer were measured at the heat treatment times shown in Table 1. The results are shown in Table 1. Example 9 80 parts of tert-butyl methacrylate, 20 parts of methyl methacrylate, 0.001 part of 2,2'-azobisisobutyronitrile and tert-dodecyl mercaptan
Dissolve 0.1 part and place in a glass ampoule.
After carrying out a thermal decomposition reaction in an oil bath in the same manner as in Example 1, its physical properties were measured. This result is the first
Shown in the table. Example 10 100 parts of tert-butyl methacrylate, 0.01 part of 2,2'-azobylisobutyronitrile and 0.1 part of tert-dodecyl mercaptan were dissolved and placed in a glass ampoule, cooled at liquid nitrogen temperature, and then desorbed. The tube was sealed in a nitrogen atmosphere by repeatedly blowing the tube. Next, this sealed ampoule was placed in a heating bath and heated at 70°C for 15 hours, and then further heated at 120°C for 3 hours to complete polymerization. The reaction conversion rate of monomer in this polymerization is
It was 95%. Next, the resulting polymer was dissolved in tetrahydrofuran and then poured into dimethylformamide for precipitation, which was repeated several times to purify the polymer. The intrinsic viscosity of this purified polymer is 0.43
It was DL/GR. The results of measuring the infrared absorption spectrum of this polymer are shown in FIG. Absorption based on the stretching vibration of the ester carbonyl was measured at a wave number of 1720 cm ^-1 . Next, this polymer was placed in a glass tube and subjected to a thermal decomposition reaction at 230° C. for 5 hours in an oil bath under a nitrogen atmosphere. In this reaction, isobutene was produced as a volatile organic gas, and the production of water was also confirmed.
After the reaction was completed, volatile components were removed under reduced pressure of 1.0 mmHg for 1 hour to obtain a foamed white resin body. Next, this resin body was crushed. The intrinsic viscosity of this ground polymer was 0.40 dl/gr. This polymer dimethylformamide 10 (weight/
When dissolved as a solution (volume)%, it was visually determined that the solution was uniformly dissolved. This solution was centrifuged at 15,000 times/min to check for the presence of gel components in the precipitate, and it was found to be a homogeneous solution with no gel components present. Further, this polymer was heated and pressure molded at 250° C. and 150 kg/cm ² to prepare a film with a thickness of 150 μm, and the dynamic viscoelasticity was measured. The loss modulus (E″) dispersion peak was 158°C. Similarly, a flat plate of 10 x 10 x 5 mm (thickness) was prepared and the Vikatsu softening point was measured, and it showed a value of 165°C. When the glass transition temperature was measured using a differential scanning calorimeter, the temperature was between 155 and 181°C.Furthermore, the infrared absorption spectrum of the above molded film was measured.The results are shown in Section 4. As shown in the figure.
As can be seen from Figure 4, absorption of acid anhydride carbonyl stretching vibrations due to the formation of glutaric anhydride groups was confirmed at wave numbers of 1756 cm ^-1 and 1802 cm ^-1 . Furthermore, when the thermally decomposed polymer was extruded using a melt indexer (manufactured by Toyo Seiki Seisakusho) at 230°C under a load of 10 kg, a good strand-shaped resin body was obtained, showing an MI value of 3.9 gr/10 min. Table 1 shows the main physical properties obtained. Examples 11-13 100 parts of tert-butyl methacrylate, 0.01 part of 2,2'-azobisisobutyronitrile and 0.1 part of tert-dodecyl mercaptan were dissolved and placed in a glass ampoule, and the polymer was prepared in the same manner as in Example 9. was prepared and a purified polymer was obtained. This polymer was subjected to a thermal decomposition reaction at 230° C. for 30 minutes in an oil bath in the same manner as in Example 9. The reaction conversion rate of this thermally decomposed product was 40% based on the amount of acid anhydride absorbed in the infrared absorption spectrum. Next, thermal decomposition treatment was performed for the heat treatment time shown in Table 1, and the physical properties of the obtained polymer were measured.
The results are shown in Table 1. Comparative Example 1 100 parts of methyl methacrylate, 0.01 part of 2,2'-azobisisobutyronitrile, and 0.1 part of tert-dodecyl mercaptan were dissolved and placed in a glass ampoule, cooled under liquid nitrogen temperature, and then desorbed. The tube was then sealed under a nitrogen atmosphere. Next, place this sealed ampoule in a heating bath at 70°C.
After heating at 12° C. for 15 hours, the mixture was further heated at 12° C. for 3 hours to complete polymerization. The reaction conversion rate of monomers in this polymerization was 97%. Next, the resulting polymer was dissolved in tetrahydrofuran and then poured into n-hexane for precipitation, which was repeated several times to purify the polymer. This purified polymer had the following properties. Number average molecular weight (Mn); 5.71×10 ⁴ Weight average molecular weight (Mw); 14.3×10 ⁴ Z average molecular weight (Mz); 20.0×10 ⁴ Mw/Mn=2.68, Mz/Mn=3.50 Intrinsic viscosity; 0.30 dl/ gr When the infrared absorption spectrum of this polymer was measured, absorption based on the stretching vibration of the ester carbonyl was measured at a wave number of 1720 cm ^-1 . Next, this polymer was placed in a glass tube and subjected to a thermal decomposition reaction at 230° C. for 5 hours in an oil bath under a nitrogen atmosphere. Volatile organic gas was produced in this reaction, and the volatile gas component was methyl methacrylate monomer, which was due to depolymerization of the polymer main chain. After the reaction was completed, volatile components were removed under reduced pressure of 1.0 mmHg for 1 hour to obtain a transparent resin body. Next, this resin body was crushed. This pulverized polymer had the following physical properties. Number average molecular weight (Mn); 5.20×10 ⁴ Weight average molecular weight (Mw); 13.5×10 ⁴ Z average molecular weight (Mz); 17.8×10 ⁴ Mw/Mn=2.6, Mz/Mn=3.42 Intrinsic viscosity; 0.27 dl/ gr Chloroform 10% (polymerization/volume) of this polymer
When dissolved as a solution, it was visually determined that it was uniformly dissolved. This solution was centrifuged at 15,000 times/min to confirm the presence or absence of gel components in the precipitate, and it was found that the solution was homogeneous and no gel components were present. This polymer sample was molded under heat and pressure at 250° C. and 150 kg/cm ² to form a film with a thickness of 150 μm, and its dynamic elasticity was measured. The dispersion peak of the loss modulus (E'') was 107°C. A flat plate of 10 x 10 x 5 mm (thickness) was prepared in the same manner and the Vikato softening point was measured, and it showed a value of 98°C. In addition, when the glass transition temperature was measured using a differential scanning calorimeter, the temperature was 78 to 109.
It was between ℃ and ℃. Furthermore, when the infrared absorption spectrum of the above molded film was measured, absorption of the stretching vibration of the ester carbonyl was observed at a wave number of 1720 cm ^-1 , but the absorption at a wavelength of 1756 cm ^-1 and the same as that of the polymer before the thermal decomposition reaction was observed.
No absorption of acid anhydride carbonyl stretching vibration due to the formation of glutaric anhydride groups at 1802 cm ^-1 was observed. In addition, when the thermally decomposed polymer was extruded using a melt indexer (manufactured by Toyo Seiki Seisakusho) at 230°C under a load of 10 kg, a good strand-shaped resin body was obtained, showing an MI value of 15 gr/10 min. Table 1 shows the main physical properties obtained.

【table】

【table】 [Brief explanation of the drawing]

Figures 1 and 2 show the infrared absorption spectra of the polymer obtained in Example 1, and Figure 3 shows the infrared absorption spectrum of the polymer obtained in Example 1.
4 and 4 show infrared absorption spectra for the polymer obtained in Example 10.

Claims (1)

[Claims] 1 A mixture consisting of 5% by weight or more of tert-butyl acrylate or tert-butyl methacrylate and 95% by weight or less of at least one ethylenic monomer selected from the group consisting of acrylic esters, methacrylic esters and styrene. A method for producing a thermoplastic polymer with excellent heat resistance, which comprises thermally decomposing a polymer obtained by polymerization at 200 to 450°C.