JPH0460129B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a novel method for producing a 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 used in home appliances, optical parts for vehicles, instrument panels, window materials for lighting, etc.
It is widely used, and in recent years it has also come to be used for special purposes such as optical fiber materials. However, these vinyl polymerizable thermoplastic resins have the disadvantage that they depolymerize when heated and are easily decomposed into their monomers. For this reason, there is a strong demand for these resins to have increased heat resistance. As a method for improving the heat resistance of these vinyl polymerizable thermoplastic resins, a method of introducing a maleic anhydride structure as described in JP-A-55-102614 and JP-A-57-153008 has been proposed. This method increases heat resistance by forming a ring structure in the main chain of the polymer to impart rigidity. The copolymerization properties of maleic anhydride are quite different from those of other divinyl monomers, and it is known that a good way to improve the copolymerization properties is to use styrene as a copolymerization monomer. . In this case, the heat resistance of the maleic anhydride/styrene copolymer is improved by forming a five-membered ring structure of maleic anhydride in the polymer main chain. Such polymers include, for example,
There are methyl methacrylate/maleic anhydride/styrene ternary copolymers and quaternary copolymers obtained by copolymerizing these ternary polymers with other vinyl monomers. However, since these polymers are multi-component copolymerized polymers, they are not only difficult to manufacture, but also the transparency of the obtained polymers is not always good. This had the fatal drawback that the physical properties of the polymer itself were significantly deteriorated due to the formation of volatile matter as a result of the reaction. A method for obtaining a polymer that is easy to produce and has excellent heat resistance, heat decomposition resistance, and transparency is to thermally decompose a polymethacrylic acid polymer to add a glutaric anhydride ring structure to the polymer main chain. There are known ways to introduce it. 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 (1960) by Grant and N. Grassie
It is described in. 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, resulting in 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. [Object of the Invention] An object of the present invention is to provide a novel method for producing a polymer having thermoplasticity, transparency, heat resistance, and heat decomposition resistance. [Summary of the Invention] The method for producing a thermoplastic polymer of the present invention includes 5% by weight or more of tert-butyl acrylate or tert-butyl methacrylate, and at least one member selected from the group consisting of acrylic esters, methacrylic esters, and styrene. 95% by weight of ethylenic monomer
It is characterized in that a polymer obtained by copolymerizing a mixture consisting of the following is thermally decomposed at 130 to 450°C in the presence of an antioxidant. In the present invention, the tert-butyl (meth)acrylate component in the raw material polymer is thermally decomposed to introduce a glutaric anhydride ring structural unit into the polymer main chain, thereby improving the heat resistance of the polymer. It is an essential ingredient for improving sex. The content of the tert-butyl (meth)acrylate component in the polymer is 5% by weight or more. This is because if the content is less than 5% by weight, a highly heat-resistant polymer cannot be obtained. In addition to the above-mentioned tert-butyl (meth)acrylate, the raw material polymer used in the present invention includes at least one type of ethylene selected from the group consisting of substituted styrenes such as styrene and chlorostyrene, acrylic esters, and methacrylic esters. Contains sexual monomers. Examples of acrylic esters or methacrylic esters (hereinafter referred to as (meth)acrylic esters) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl ( Mention may be made of alkyl (meth)acrylates containing aliphatic or aromatic functional groups having 1 to 18 carbon atoms, such as meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, and benzyl (meth)acrylate. . These ethylenic monomers are preferably those that do not easily become colored by heating, and from this point of view, methacrylic monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, and 2,2, Fluorinated alkyl methacrylate monomers such as 2-trifluoroethyl methacrylate and 2,2,3,3,3-tetrafluoropropyl methacrylate are preferred, and methyl methacrylate is particularly preferred. The raw material polymer used in the present invention contains one or more of the above ethylenic monomers. Further, the content of the ethylenic monomer component in the raw material polymer is 95% by weight or less. In the method for producing a thermoplastic polymer of the present invention, a raw material polymer is thermally decomposed in the presence of an antioxidant. Antioxidants are essential elements for preventing oxidation of raw polymers during thermal decomposition treatment and the accompanying deterioration of mechanical strength of the polymers. Examples of the antioxidants used include phosphite-based antioxidants, hindered phenol-based antioxidants, sulfur-based antioxidants, and amine-based antioxidants. Phosphite-based antioxidants include phosphite-based compounds such as tricresyl phosphite, cresyl phenyl phosphite, trioctyl phosphite, butoxyethyl phosphite, etc., and hindered phenol-based antioxidants include hydroquinone, Derivatives such as cresol and phenol can be used as sulfur-based antioxidants, derivatives such as alkyl mercaptan and dialkyl sulfide can be used as sulfur-based antioxidants, and derivatives such as naphthylamine, phenylenediamine, and hydroquinoline can be used as amine-based antioxidants. . The thermal decomposition treatment temperature of the raw material polymer is 130 to 450℃,
Preferably the temperature is 150 to 300°C. Further, it is preferable to use an inert gas atmosphere such as nitrogen or argon as the thermal decomposition treatment atmosphere. This is because when an active gas is used, abnormal reactions often occur, making it impossible to obtain the desired polymer. The polymer thus obtained is substantially free of intermolecular crosslinks. 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. Additionally, undissolved particles in the polymer solution can be measured optically (e.g., light scattering method) or physically (e.g., centrifugation method) to confirm the presence or absence of a crosslinked structure in the polymer. You can. In the centrifugation method, it is also possible to separate the crosslinkable polymer in a gel state using a centrifuge. In addition, the obtained polymer has an intrinsic viscosity of 0.01 to 2.
Preferably it is 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=(1nηrel)/c (In the formula, c represents the number of grams of polymer per 100 ml of solvent.) [Effects of the Invention] The production method of the present invention can easily produce thermoplastic resins with excellent heat resistance and transparency. It has the advantage of providing a polymer, and the resulting polymer can be used as various molding materials, coating materials, resist materials, optical materials, heat-resistant films, etc. In addition, materials with relatively high intrinsic viscosity are suitable as molding materials and fiber materials that are melt-shaped. Further, when this polymer is used in combination with a crosslinking agent such as a low molecular weight polyamine, a resin composition exhibiting crosslinking and curable properties can be obtained. Furthermore, a polymer having a glutarimide ring structure can be obtained by subjecting the thermoplastic polymer of 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] Hereinafter, the thermoplastic polymer of the present invention will be explained in more detail with reference to Examples. In these Examples, the properties of the polymers were measured by the following method. The infrared absorption spectrum was measured using an infrared spectrophotometer (Co., Ltd.).
It was measured by the KBr disc method using a Hitachi Model 258). 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 tetrahydrofuran, and the flow rate was 1.2
The measurement was performed at ml/min, and a monodisperse polystyrene calibration curve was used as the calibration curve. 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). In addition, gear open (KH− manufactured by Tabai Seisakusho Co., Ltd.)
Thermal decomposition properties were evaluated by isothermal analysis to determine the weight change after holding at 270°C for a certain period of time in a 180 centrifuge). As a simple method for the solubility test, the solubility in a specific solvent was visually tested. At the same time, by centrifugation method (KH-180 centrifuge manufactured by Kubota Seisakusho Co., Ltd.)
After centrifugation at 15,000 rpm for 60 minutes, solubility was evaluated based on the presence or absence of gel components. Tropical colors based on thermal decomposition reactions were evaluated using a Hunter colorimeter (Hitachi Color Analyzer Model 307) using the yellowness index YI (yellow index) according to Hunter's formula below. YI=(A-B)/G...() In the formula, A=1.28X-0.212, B=0.847Z, G=Y
, and X is the red color of the reflected spectrum light.
Y represents the measured stimulus value obtained from the intensity of the reflected wavelength having a green stimulus and Z represents a blue stimulus (see Color Science Handbook, page 238, edited by the Color Science Association, Nankodo). Note that "parts" described below 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 When the infrared absorption spectrum of this polymer was measured, absorption based on stretching vibration of ester carbonyl was observed at a wave number of 1720 cm ^-1 . Next, this polymer was crushed, and after adding 0.5 part of a phenolic antioxidant Irganox 1076 (manufactured by Ciba Geigy), it was subjected to a thermal decomposition reaction at 230° C. for 3 hours in an oil bath under a nitrogen atmosphere. In this reaction, the production of isobutene, methanol, and water as volatile organic gas components was 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. The polymer powder obtained by crushing this resin body had the following physical properties. Number average molecular weight (Mn); 8.25×10 ⁴ Weight average molecular weight (Mw); 17.8×10 ⁴ Z average molecular weight (Mz); 28.2×10 ⁴ Mw/Mn=2.16, z/Mn=3.42 Intrinsic viscosity; 0.33 dl/ gr Dimethylformamide 10 (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. Further, this weight body was heated and press-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 dispersion peak of the loss modulus (E″) appeared at 147°C. Furthermore, the glass transition temperature determined using a differential scanning calorimeter was between 123 and 154°C. As a result of measuring the infrared absorption spectrum, in addition to the absorption of the stretching vibration of ester carbonyl at a wave number of 1720 cm ^-1 , there was also absorption of the stretching vibration of the ester carbonyl at a wave number of 1756 and 1720 cm -1.
Absorption of acid anhydride carbonyl stretching vibration due to the formation of glutaric anhydride group was confirmed at 1802 cm ^-1 . In the same way, a flat plate of 10 x 10 x 5 mm (thickness) was made and the Vikatsuto softening point was measured, and the value was
It was 153℃. Next, this polymer was extruded using a melt indexer (Toyo Seiki Seisakusho) at 230°C under a load of 10 kg, and a good strand-shaped resin body was obtained.
It showed an MI value of 5.8gr/10min. Next, this polymer was extruded using a 25φ vented extruder (manufactured by Daiichi Jitsugyo Co., Ltd., die temperature 230°C, adapter temperature 230°C).
After extrusion molding using a full-flight screw L/D=24, the screw barrel temperature was 200 to 230°C and pelletized. Using this pelletized weight, a flat molded plate (60 x 80 x 2 mm) was obtained using a 1 oz vertical screw type injection molding machine (SAV-30A manufactured by Yamashiro Seiki Seisakusho). The optical properties of this resin molded plate were measured according to ASTM D-1003, and the total light transmittance was
92%, haze value was 3.0. Further, when the yellowness (yellow index value) YI value was measured using this Hitachi Color Analyzer Model 307, it was 2.5. Table 1 shows the main physical properties of this polymer. Examples 2 to 15 Raw material polymers were prepared by repeating the same operations as in Example 1 using monomer compositions and antioxidants as shown in Table 1, and were heat-treated to produce the present invention. A polymer was obtained by the method. The physical property measurement 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 degassed. The tube was sealed under a nitrogen atmosphere. Next, place this sealed ampoule in a heating bath at 70°C.
After heating at 120° C. for 15 hours, the mixture was further heated at 120° C. for 3 hours to complete polymerization. The reaction conversion rate of monomers in this polymerization was 97%. Next, the resulting heavy product 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 physical 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 stretching vibration of ester carbonyl was observed 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. The polymer powder obtained by crushing this resin body 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 This polymer was mixed with 10% (weight/volume) chloroform.
It was visually determined that the polymer dissolved uniformly when mixed as a mixture. Add this solution to 15000
The presence or absence of a gel component in the precipitate was confirmed by centrifugation at a rate of 3 times per minute, and it was found that the solution was homogeneous and no gel component was 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 viscoelasticity was measured. The dispersion peak of the loss modulus (E″) was 107°C. Similarly, a flat plate of 10 x 10 x 5 mm was prepared and the Vikat softening point was measured, and it was 98°C. When the glass transition temperature was measured using a meter, the temperature was between 78 and 109°C.Furthermore, when the infrared absorption spectrum of the above molded film was measured, it was found that ester was present at a wave number of 1720 cm ^-1. Absorption of stretching vibrations of carbonyl was observed, but the wavelengths were 1756 and 1802 cm, similar to that of the polymer before thermal decomposition reaction.
No absorption of acid anhydride carbonyl stretching vibration was observed in ^-1 due to the formation of glutaric anhydride groups. In addition, a good strand-shaped resin body was obtained by extruding the thermally decomposed polymer using a melt indexer (manufactured by Toyo Seiki Seisakusho) at 230°C and under a load of 10 kg.
It showed an MI value of 15gr/10min. Further, when the yellowness (yellow index value) YI value was measured using this Hitachi Color Analyzer Model 307, it was 0.5. Table 1 shows the main physical properties obtained. Comparative Example 2 A raw material polymer was prepared by repeating the same operations as in Example 1 using a monomer composition and an antioxidant as shown in Table 1, and then heat-treated to prepare a comparative polymer. Obtained union. The results of measuring its physical properties are shown in the first
Shown in the table. Comparative Example 3 A comparative polymer was obtained by subjecting a polymer having the monomer composition shown in Table 1 to the same heat treatment as in Examples 13 and 14 without using an antioxidant.
Table 1 shows the results of measuring its physical properties.

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Claims (1)

[Claims] 1. 5% by weight or more of tert-butyl acrylate or tert-butyl methacrylate and 95% by weight of 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 the following is heated at 130 to 450℃ in the presence of an antioxidant.
A method for producing a thermoplastic polymer with excellent heat resistance, characterized by thermal decomposition at . 2. The method for producing a thermoplastic polymer according to claim 1, wherein the antioxidant is a phosphite compound, a phenol compound, a sulfur compound, or an amine compound.