JP2006124438A - Method for producing thermoplastic copolymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a thermoplastic copolymer having excellent heat-resistance, colorlessness and transparency and containing little foreign materials. <P>SOLUTION: A thermoplastic copolymer (B) containing a glutaric acid anhydride unit expressed by general formula (1) (R<SP>1</SP>and R<SP>2</SP>are each independently hydrogen atom or a 1-5C alkyl) is produced by the 1st step to produce a copolymer (A) containing (i) an unsaturated carboxylic acid alkyl ester unit and (ii) an unsaturated carboxylic acid unit and the 2nd step to perform the intramolecular cyclization reaction of the copolymer (A). The 1st step contains a step to copolymerize the monomer mixture in an organic solvent (C) free from aromatic group, dissolving the monomer mixture used as the raw material and having a solubility of the copolymer (A) of ≤1 g/100 g. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a glutaric anhydride unit-containing thermoplastic copolymer that is excellent in heat resistance, molding processing characteristics, and colorless transparency, and that contains particularly few foreign substances.

  Amorphous resins such as polymethyl methacrylate (hereinafter referred to as “PMMA”) and polycarbonate (hereinafter referred to as “PC”) make use of transparency and dimensional stability of optical materials, household electrical appliances, office automation equipment, automobiles, and the like. It is used in a wide range of fields including parts.

  In recent years, these resins have been widely used in higher performance optical materials such as optical lenses, prisms, mirrors, optical disks, optical fibers, liquid crystal display sheets and films, light guide plates, etc. The optical properties, moldability, and heat resistance required for these products are also higher.

  At present, these transparent resins are also used as lamp members for automobiles such as tail lamps and head lamps, but in recent years, tail lamp lenses, inner lenses, There is a tendency to reduce the distance between various light sources such as headlamps and shield beams and the light source, and to reduce the thickness of the parts, and excellent moldability is required. Further, since the vehicle is used under severe conditions, it is required to have a small shape change under high temperature and high humidity, and excellent scratch resistance, weather resistance, and oil resistance.

  However, although PMMA resin has excellent transparency and weather resistance, there is a problem that heat resistance is not sufficient. On the other hand, PC resin is excellent in heat resistance and impact resistance, but has a large birefringence, which is an optical distortion, and has optical anisotropy in the molded product, remarkably in moldability, scratch resistance, and oil resistance. There was a problem of being inferior.

  Therefore, for the purpose of improving the heat resistance of PMMA, a resin in which a maleimide monomer or a maleic anhydride monomer is introduced as a heat resistance imparting component has been developed. However, maleimide monomers are expensive and have low reactivity, and maleic anhydride has a problem of poor thermal stability.

  As a method for solving these problems, a copolymer containing an unsaturated carboxylic acid monomer unit is heated using an extruder to contain a glutaric anhydride unit obtained by a cyclization reaction. For example, Patent Document 1 discloses a copolymer, but there is a problem that a copolymer having a glutaric anhydride unit obtained by heat-treating the copolymer using an extruder is markedly colored. .

  Also disclosed is a method for producing a copolymer containing glutaric anhydride units by heating a polymer solution containing unsaturated carboxylic acid monomer units under vacuum (see Patent Document 2). . However, in the methods described in these publications, in order to remove the solvent completely under vacuum, heat treatment for a long time is required at a high temperature, and much labor and energy are required. there were. Further, when a polymer containing an unsaturated carboxylic acid monomer is produced in a solution, it is necessary to increase the polymerization temperature in order to obtain a high polymerization rate, and the polymer is heated under vacuum in a solution. However, the coloration-suppressing effect of the copolymer containing the resulting glutaric anhydride unit is not sufficient, and the recent requirement for higher colorlessness has not been met.

  Therefore, as disclosed in Patent Document 3, the present inventors produced a copolymer containing a specific unsaturated carboxylic acid unit under specific polymerization conditions, and then heat-treated the copolymer to give colorless. A production method of glutaric anhydride-containing copolymer with excellent transparency and retention stability was proposed. According to the technique proposed in Patent Document 3, the coloration and retention stability of the resulting copolymer have been greatly improved. However, such as optical lenses, prisms, mirrors, optical disks, optical fibers, liquid crystal display sheets and films, light guide plates, etc. For use in higher performance optical materials, a glutaric anhydride-containing copolymer with less unmelted foreign matter such as so-called fish eyes as well as higher colorless transparency has been desired.

  On the other hand, the technique regarding the crosslinkable optical material containing the polymer manufactured by precipitation polymerization is known (refer patent document 4). According to the present technology, it is said that a transparent, high refractive index and lightweight crosslinkable optical material can be provided, and precipitation polymerization is “a solvent that dissolves a polymerizable monomer that is a precursor but does not dissolve a polymer. In this method, the polymerizable monomer is dissolved and the solution is polymerized to recover a polymer having a certain degree of polymerization as a precipitate.

  However, in Patent Document 4, an unsaturated carboxylic acid monomer and an unsaturated carboxylic acid alkyl ester monomer are selected as copolymerization species, and a copolymer is formed using a specific organic solvent, which is further cyclized. There is no mention of what to do. Non-Patent Documents 1 and 2 disclose a precipitation polymerization method using a solvent containing an aromatic group such as benzene or toluene for copolymerization of an unsaturated carboxylic acid monomer. However, according to the study by the present inventors, when a monomer mixture containing an unsaturated carboxylic acid monomer and an unsaturated carboxylic acid alkyl ester is copolymerized using the above-mentioned solvent, there is a problem in the monomer mixture. Since the dimerization of saturated carboxylic acid monomer occurs remarkably and forms a partially inhomogeneous phase or chain transfer to the solvent is inevitable, the copolymer composition and molecular weight of the resulting copolymer are It was found that it was difficult to control precisely, and in particular, there was a problem that the molecular weight distribution became extremely large.

Furthermore, a method for producing polymer fine particles produced by a dispersion polymerization method is known (see Patent Document 5). Also in Patent Document 5, an unsaturated carboxylic acid monomer and an unsaturated carboxylic acid alkyl ester monomer are selected as copolymerization species, a copolymer is prepared using a specific organic solvent, and this is further cyclized. No mention is made.
JP-A-49-85184 (page 1-2, Examples) JP-A-60-120707 (page 1-2, Examples) JP 2004-002711 A (page 1-2, Examples) JP-A-8-217847 Japanese Patent Laid-Open No. 10-218935 Die Angewandte Makromolekuare Chemie 11 (1970) p53-62 Journal of Polymer Science: Polymer Letters Edition, Vol.18 (1980), p241-248

  Therefore, the present invention has high heat resistance, colorless transparency, and excellent heat processing stability, and at the same time, reduces foreign matters present in the copolymer, and is required for optical materials. It is an object of the present invention to provide a method for producing a thermoplastic copolymer that satisfies colorless transparency and low foreign matter.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors obtained a copolymer containing the unsaturated carboxylic acid unit, which is a precursor of a thermoplastic copolymer containing a glutaric anhydride unit. In the production, by using a specific polymerization solvent, colorless transparency, excellent molding process characteristics with excellent thermal stability, high quality satisfying low foreign matter, which could not be achieved with conventional knowledge, The present inventors have found that a copolymer containing glutaric anhydride can be produced easily and economically easily by separating the polymer from a solvent, and have reached the present invention.

That is, the present invention
[1] A step (first step) of producing a copolymer (A) containing (i) an unsaturated carboxylic acid alkyl ester unit and (ii) an unsaturated carboxylic acid unit, followed by the copolymer (A And (ii) dehydration and / or (b) intramolecular cyclization reaction by dealcoholization reaction (second step), (iii) glutaric acid represented by the following general formula (1) In producing a thermoplastic copolymer (B) containing an anhydride unit and (i) an unsaturated carboxylic acid alkyl ester unit, as the first step, an organic solvent containing no aromatic group, A monomer mixture containing an unsaturated carboxylic acid alkyl ester monomer and an unsaturated carboxylic acid monomer dissolves in an organic solvent (C) in which the solubility of the copolymer (A) is 1% by weight or less. A step of copolymerizing the monomer mixture. Process for producing a thermoplastic copolymer, characterized in that,

(However, R < ¹ >, R < ² > represents the same or different hydrogen atom or a C1-C5 alkyl group.)
[2] In the copolymerization of the monomer mixture in the first step, the absolute value (ΔSP) of the difference between the solubility parameter of the copolymer (A) and the solubility parameter of the organic solvent (C) is 1.0 or more. The method for producing a thermoplastic copolymer according to the above [1], which is carried out under a certain condition,
[3] In the copolymerization of the monomer mixture in the first step, the absolute value (ΔSP) of the difference between the solubility parameter of the copolymer (A) and the solubility parameter of the organic solvent (C) is 1.5 to 1. The method for producing a thermoplastic copolymer according to the above [1], wherein the method is carried out under a condition of 0.7.
[4] The organic solvent (C) used in the first step is one or more selected from aliphatic hydrocarbons, carboxylic acid esters, and ketones, and any one of the above [1] to [3] A process for producing a thermoplastic copolymer of
[5] The thermoplastic copolymer as described in any one of [1] to [4] above, wherein the organic solvent (C) used in the first step is a mixture of an aliphatic hydrocarbon and a carboxylic acid ester. Manufacturing method,
[6] The organic solvent (C) used in the first step is a mixture of an aliphatic hydrocarbon and a carboxylic acid ester, and the weight ratio thereof is 5/95 to 70/30. A process for producing the thermoplastic copolymer according to claim 1,
[7] The method for producing a thermoplastic copolymer according to any one of [1] to [6] above, wherein (ii) the unsaturated carboxylic acid unit is contained in the copolymer (A) in an amount of 15 to 50% by weight,
[8] The method for producing a thermoplastic copolymer as described in any one of [1] to [7] above, wherein the heat treatment in the second step is performed using a continuous kneading extruder.
[9] In the continuous kneading and extruding device, the first shaft extending from the biaxial screw portion and the biaxial screw portion in which the first shaft and the second shaft forming the screw portion are arranged in parallel are arranged in the casing. The biaxial screw portion and the monoaxial screw portion are provided with a flow rate adjusting mechanism, the casing is provided with a raw material supply port communicating with the biaxial screw portion, and the extension [8] The method for producing a thermoplastic copolymer as described in [8] above, which is a biaxial / single-shaft composite continuous kneading and extruding apparatus having a discharge port communicating with the end of the first shaft.

  According to the present invention, it has high heat resistance, colorless transparency, and excellent heat processing stability, and at the same time, reduces foreign matter present in the copolymer, and is highly colorless and transparent required for optical materials. It has become possible to produce a thermoplastic copolymer that satisfies the properties and low foreign matter.

  Hereafter, the manufacturing method of the thermoplastic copolymer (B) of this invention is demonstrated concretely.

  The thermoplastic copolymer (B) of the present invention is (iii) a thermoplastic copolymer containing a glutaric anhydride unit represented by the following general formula (1) and (i) an unsaturated carboxylic acid alkyl ester unit. These can be used alone or in combination of two or more.

(In the above formula, R ¹ and R ² represent the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms)
The method for producing a thermoplastic copolymer containing a glutaric anhydride unit represented by the general formula (1) of the present invention is basically produced by the following two steps. That is, an unsaturated carboxylic acid alkyl ester monomer and an unsaturated carboxylic acid monomer that give the glutaric anhydride unit represented by the general formula (1) in the subsequent heating step, and other vinyl-based compounds When a monomer unit is included, a step of copolymerizing a vinyl monomer giving the unit to produce a copolymer (A) (first step), followed by the copolymer (A ) Is heated in the presence or absence of a suitable catalyst and (i) dehydration and / or (b) intramolecular cyclization reaction by dealcoholization is carried out (the second step). It is. In this case, typically, the copolymer (A) is heated to dehydrate the carboxyl group of 2 units of (ii) the unsaturated carboxylic acid unit, or adjacent to (ii) the unsaturated carboxylic acid unit. (I) One unit of the glutaric anhydride unit is generated by elimination of the alcohol from the unsaturated carboxylic acid alkyl ester unit.

  The unsaturated carboxylic acid monomer used in the first step is not particularly limited, and any unsaturated carboxylic acid monomer that can be copolymerized with other vinyl compounds can be used. As a preferable unsaturated carboxylic acid monomer, the following general formula (2)

(However, R ³ represents hydrogen or an alkyl group having 1 to 5 carbon atoms)
In particular, acrylic acid and methacrylic acid are preferred, and methacrylic acid is more preferred from the viewpoint of excellent thermal stability. These can be used alone or in combination. The unsaturated carboxylic acid monomer represented by the general formula (2) gives an unsaturated carboxylic acid unit having a structure represented by the following general formula (3) when copolymerized.

  Moreover, there is no restriction | limiting in particular as an unsaturated carboxylic-acid alkylester type monomer, However, As a preferable example, what is represented by following General formula (4) can be mentioned.

(However, R ⁴ represents hydrogen or an alkyl group having 1 to ⁵ carbon atoms, and R ⁵ represents an aliphatic or alicyclic hydrocarbon group having 1 to 6 carbon atoms, or a hydroxyl group or halogen having a number of 1 to ⁵ carbon atoms. A C1-C6 aliphatic or alicyclic hydrocarbon group substituted with
Among these, an acrylate ester and / or a methacrylic ester having an aliphatic or alicyclic hydrocarbon group having 1 to 6 carbon atoms or the hydrocarbon group having a substituent is particularly preferable. The unsaturated carboxylic acid alkyl ester monomer represented by the general formula (4) gives an unsaturated carboxylic acid alkyl ester unit having a structure represented by the following general formula (5) when copolymerized.

  Preferred specific examples of unsaturated carboxylic acid alkyl ester monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, Examples thereof include monomers such as dodecyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, benzyl methacrylate, lauryl methacrylate, dodecyl methacrylate, and trifluoroethyl methacrylate. Of these, methyl methacrylate and ethyl methacrylate are preferable, and methyl methacrylate is particularly preferable from the viewpoint of excellent optical characteristics and thermal stability. These may be used alone or as a mixture of two or more.

  In the first step, other vinyl monomers may be used as long as the effects of the present invention are not impaired. Preferable specific examples of other vinyl monomers include fragrances such as styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, and pt-butylstyrene. Vinyl cyanide monomers such as aromatic vinyl monomers, acrylonitrile, methacrylonitrile, ethacrylonitrile, etc., but includes aromatic rings in terms of transparency, birefringence, and chemical resistance Less monomers can be used more preferably. These may be used alone or in combination of two or more.

  Regarding the polymerization method in the first step, an unsaturated carboxylic acid alkyl ester monomer and an unsaturated solvent which are organic solvents not containing an aromatic group in the presence or absence of a polymerization initiator and which are raw materials The monomer mixture containing the carboxylic acid monomer is dissolved, and the solubility of the copolymer (A) containing (i) the unsaturated carboxylic acid alkyl ester unit and (ii) the unsaturated carboxylic acid unit is 1 g / 100 g or less. It is necessary to polymerize in some organic solvent (C). That is, it is obtained by a so-called “precipitation polymerization method” in which the copolymer (A) is precipitated from an organic solvent phase containing a uniform monomer mixture as the polymerization reaction proceeds. In this case, the copolymer (A) can be isolated by filtering and drying the slurry solution after polymerization.

  Here, “the solubility of the copolymer (A)” means the amount of the copolymer (A) dissolved in 100 g of the organic solvent (B) after stirring at 23 ° C. for 24 hours.

  In the present invention, it is necessary to consider the balance of solubility in the copolymer (A) and the organic solvent (B) in order to easily precipitate and precipitate the copolymer (A). From this point of view, it is preferable to design polymerization conditions such as copolymer species, copolymer composition, and reaction solvent in consideration of solubility parameters of each component.

  Among them, in the present invention, the difference between the solubility parameter δp of the copolymer (A) containing (i) the unsaturated carboxylic acid alkyl ester unit and (ii) the unsaturated carboxylic acid unit and the solubility parameter δs of the organic solvent (C) It is preferable to select a copolymer composition and a solvent type such that the absolute value (ΔSP) is 1.0 or more, more preferably 1.1 or more, and polymerization is performed particularly under 1.2 or more. However, there is no adhesion to the wall of the polymerization tank during polymerization, and it is preferable for easily taking out the resulting copolymer as a powder. In addition, by designing the polymerization conditions in the above-described ΔSP in the range of 1.0 to 1.9, more preferably in the range of 1.2 to 1.8, and still more preferably in the range of 1.5 to 1.7, Precise control that does not cause a large shift between the composition of the charged monomer mixture before the start of polymerization and the copolymer composition of the copolymer to be produced, and narrow molecular weight distribution and high molecular weight control It was found that the effect of greatly improving the thermal stability and colorless transparency of the thermoplastic copolymer (B) obtained through the second step was developed.

  The solubility parameter δp of the copolymer (A) containing (i) an unsaturated carboxylic acid alkyl ester unit and (ii) an unsaturated carboxylic acid unit is preferably 7.0 to 12.0, more preferably 7. 5 to 10.5 is desirable. When δp is less than 7.0, the thermoplastic copolymer (B) obtained through the second step is inferior in gasoline resistance and oil resistance, and may be subject to many practical limitations. When δp exceeds 12.0, the cohesive strength of the polymer becomes too strong, and when it is supplied to the second step, the viscosity becomes too high and the handleability tends to deteriorate.

  In addition, the solubility parameter said here is the method of Small by referring to “Introduction to Synthetic Resins for Paints”, Kyozo Kitaoka, p23-p31, Kobunshi Shuppankai (1986), Tables 2-8 and 2-9. It was calculated by.

That is, the cohesive energy constant F (cal ^1/2 cc ^1/2 / mol) of a specific atom and atomic group given by the small method, the density is s (g / cc), the basic molecular weight is M, and δ = Let the value calculated by (sΣF) / M be the solubility parameter δ. In the present invention, the cohesive energy F is a small value.

(1) Monomer solubility parameter
As an example, a calculation example of methyl methacrylate (density 0.944 g / cc) is shown.

  F of each component constituting methyl methacrylate is

It becomes. Therefore, the solubility parameter δm of methyl methacrylate is
δm = 0.944 × 947 ÷ 100 = 8.94
It becomes.

  Typical monomer solubility parameters determined by this calculation method are:

It is.

(2) Solubility parameter δp of copolymer (A)
In the present invention, the solubility parameter δp of the copolymer (A) was calculated according to the following formula. That is, it is calculated by the following formula from the molar fraction Xi (%) of each monomer in the copolymer (A) and the solubility parameter δi of each monomer.

δp = Σ (δi × Xi / 100)
Therefore, in order to bring the solubility parameter δp of the copolymer (A) into the above range, the composition may be adjusted in consideration of the solubility parameter of the monomer used.

(3) Solubility parameter δs of organic solvent (B)
The solubility parameter δs of the organic solvent (B) is obtained in the same manner as the calculation method of the solubility parameter δp of the copolymer (A). Examples of n-heptane are shown below.

δs = 0.676 × 1093 ÷ 100 = 7.39
In addition, the solubility parameter δs when the organic solvent (B) is a mixture of two or more types is calculated from the following formula based on the molar fraction Xi (%) of each solvent component in the mixed organic solvent and the solubility parameter δi of each solvent component. Is calculated by

δp = Σ (δi × Xi / 100)
The organic solvent (C) used in the present invention is not particularly limited as long as it is an organic solvent that enables the precipitation polymerization method described above, and the relationship with the copolymer (A) is within the above range. However, specific examples include one or more selected from aliphatic hydrocarbons, aromatic hydrocarbons, carboxylic acid esters, ketones, ethers, and alcohols. Among them, one or more selected from aliphatic hydrocarbons, carboxylic acid esters, and ketones are preferable. In particular, aliphatic hydrocarbons are used in that the copolymer composition and molecular weight distribution of the copolymer to be produced are more precisely controlled. One or more selected from carboxylic acid esters can be preferably used, and the relationship with the copolymer (A) as described above is more preferably selected.

  Examples of the aliphatic hydrocarbon used in the present invention include a straight chain having 5 to 10 carbon atoms, a chain having a side chain, and an alicyclic group. Specific examples include n-pentane, n-hexane, cyclohexane, n-heptane, n-octane, n-nonane, n-decane and various isomers thereof.

  The carboxylic acid ester used in the present invention is an ester composed of a saturated aliphatic carboxylic acid and a saturated alcohol. Specific examples of the saturated carboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, etc., and a saturated alcohol. Can be linear and branched having 1 to 10 carbon atoms. Preferred carboxylic acid esters include formic acid-n-propyl, isopropyl formate, formic acid-n-butyl, formic acid isobutyl, formic acid-n-pentyl, formic acid-n-hexyl, acetic acid-n-propyl, isopropyl acetate, acetic acid-n- Butyl, isobutyl acetate, acetic acid-n-pentyl, acetic acid-n-hexyl, acetic acid-n-heptyl, acetic acid-n-octyl, acetic acid-n-nonyl, methyl propionate, ethyl propionate, propionate-n-propyl, Isopropyl propionate, n-butyl propionate, isobutyl propionate, n-pentyl propionate, n-hexyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, Various different types such as isobutyl butyrate, n-pentyl butyrate, n-hexyl butyrate It can be given the body.

  The ketone used in the present invention is a ketone having 1 to 10 carbon atoms and comprising a linear and branched saturated aliphatic group. Specific examples thereof include methyl-n-butyl ketone, methyl isobutyl ketone, and ethyl isobutyl. Examples include ketones.

  Among these, in the present invention, a mixture of an aliphatic hydrocarbon and a carboxylic acid ester can be preferably used. In this case, the preferred mixing ratio of the aliphatic hydrocarbon and the carboxylic acid ester is not particularly limited, but the weight ratio is preferably in the range of 5/95 to 70/30, preferably 10/90 to 50/50, especially 20 / 80-40 / 60 is preferable. When the mixing ratio is less than 5/95, the copolymer formed during the polymerization tends to stick to the reaction vessel. On the other hand, when the mixing ratio is larger than 70/30, the copolymer has a very fine particle diameter and tends to be inferior in handleability.

  In addition, when performing precipitation polymerization in the production method of the present invention, if water is used in the polymerization reaction system, it may be difficult to precisely control the copolymer composition, and water should be kept within the controllable range of the copolymer composition. Most preferably, water is not positively added unless the component used in the polymerization reaction system such as an organic solvent contains a very small amount of water as an impurity.

  The polymerization temperature in the first step can be arbitrarily set, but is preferably a temperature not higher than the boiling point of the organic solvent to be used. Especially, it is preferable to superpose | polymerize at the polymerization temperature of 100 degrees C or less, and it is more preferable to superpose | polymerize at the polymerization temperature of 90 degrees C or less. The lower limit of the polymerization temperature is not particularly limited as long as the polymerization proceeds, but is usually 50 ° C. or higher, preferably 60 ° C. or higher from the viewpoint of productivity considering the polymerization rate. The polymerization time is not particularly limited as long as it is a time sufficient to obtain a necessary polymerization rate, but is preferably in the range of 60 to 360 minutes, and particularly preferably in the range of 90 to 240 minutes from the viewpoint of production efficiency.

  In addition, controlling the dissolved oxygen concentration in the polymerization solution to 5 ppm or less in the first step can improve the excellent colorless transparency, residence stability and thermal stability of the thermoplastic copolymer (B) after the heat treatment. Since it can be achieved, it is preferable. Furthermore, in order to further suppress coloring after the heat treatment, a preferable range of dissolved oxygen concentration is 0.01 to 3 ppm, and more preferably 0.01 to 1 ppm. When the dissolved oxygen concentration exceeds 5 ppm, the thermoplastic copolymer (B) after the heat treatment tends to be colored, and the thermal stability of the thermoplastic copolymer (B) is lowered. I can't reach my goal. Here, the dissolved oxygen concentration in the present invention is a value obtained by measuring dissolved oxygen in the polymerization solution using a dissolved oxygen meter (for example, DO meter B-505 manufactured by Iijima Electronics Co., Ltd., which is a galvanic oxygen sensor). is there. For the method of reducing the dissolved oxygen concentration to 5 ppm or less, a method of passing an inert gas such as nitrogen, argon or helium into the polymerization vessel, a method of bubbling an inert gas directly into the polymerization solution, or an inert gas before starting the polymerization A method of performing pressure relief once or twice after filling the polymerization vessel, a method of degassing the closed polymerization vessel before charging the monomer mixture, and then filling with an inert gas, A method of passing an inert gas through the polymerization vessel can be exemplified.

  A preferred ratio of the monomer mixture used in the production of the copolymer (A) as the first step is such that the monomer mixture is 100% by weight and the unsaturated carboxylic acid monomer is 15 to 50%. % By weight, more preferably 20-45% by weight, unsaturated carboxylic acid alkyl ester monomer is preferably 50-85% by weight, more preferably 55-80% by weight, other vinyl-based copolymerizable with these When using a monomer, the preferable ratio is 0 to 35 weight%, and an especially preferable ratio is 0 to 10 weight%.

  When the amount of the unsaturated carboxylic acid monomer is less than 15% by weight, the amount of glutaric anhydride units represented by the general formula (1) generated by heating the copolymer (A) decreases, There exists a tendency for the heat resistance improvement effect to become small. On the other hand, when the amount of the unsaturated carboxylic acid monomer exceeds 50% by weight, a large amount of unsaturated carboxylic acid units tend to remain after the cyclization reaction by heating of the copolymer (A), which is colorless. There is a tendency for transparency and retention stability to decrease.

  In addition, these monomer mixtures may be charged in an organic solvent in a batch and copolymerized, or may be copolymerized while being added in portions or sequentially. More preferably, for the purpose of reducing the composition distribution of the monomer units constituting the copolymer (A) to be produced, the weight composition ratio in the monomer mixture is arbitrarily set and added in portions or sequentially. A method is mentioned.

  As the polymerization initiator used in the present invention, a radical polymerization initiator is preferably used. As the radical polymerization initiator, any commonly used initiator can be used. Among them, 2,2′-azobisisobutyronitrile, 2,2′-azobis-4-methoxy-2,4-dimethylvalero Azo compounds such as nitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azobis-2-methylbutyronitrile, lauroyl peroxide, benzoyl peroxide, t-butylperoxy Organic peroxides such as neodecanate, t-butyl peroxypivalate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxybenzoate, and dicumyl peroxide can be suitably used. .

  The amount of the polymerization initiator used is preferably 0.001 to 2.0 parts by weight, particularly 0.01 to 1.0 part by weight, based on the amount of the monomer mixture used for copolymerization.

  In the present invention, a chain transfer agent such as alkyl mercaptan, carbon tetrachloride, carbon tetrabromide, dimethylacetamide, dimethylformamide, and triethylamine can be added for the purpose of controlling the molecular weight.

  Examples of the alkyl mercaptan used in the present invention include n-octyl mercaptan, t-dodecyl mercaptan, n-dodecyl mercaptan, n-tetradecyl mercaptan, n-octadecyl mercaptan and the like. Among them, t-dodecyl mercaptan, n-dodecyl mercaptan is preferably used.

  The organic solvent slurry containing the copolymer (A) polymerized with the specific polymerization solvent in the present invention is separated from the copolymer (A) and the organic solvent (B) by, for example, solid-liquid separation using a centrifuge. Can be separated and fractionated, and if necessary, by drying the copolymer (A) containing about several percent of the organic solvent (B) with a shelf dryer, conical dryer, centrifugal dryer or the like, It is also possible to produce a copolymer (A) that does not contain an organic solvent (B).

  More simply, if possible, the copolymer (A) can be recovered by a spray dryer, and at the same time, the organic solvent (B) can be recovered as a dry polymer.

  The copolymer (A) produced as described above preferably has a weight average molecular weight (hereinafter also referred to as Mw) of preferably 2,000 to 1,000,000, more preferably 5,000 to 500,000.

  When Mw is less than 2000, the copolymer (A) may not be precipitated or precipitated as a dispersoid in the organic solvent (B) and may not meet the purpose of the present invention. In addition, the polymer is brittle and the mechanical properties tend to be poor. When Mw exceeds 1,000,000, high-molecular weight substances that are not sufficiently melted or dissolved in melt-molded or solution-coated products tend to remain as foreign matters, and tend to suffer from fisheye and repellency defects. .

  In the present invention, a copolymer having a homogeneous molecular weight distribution can be obtained by selecting a specific copolymer composition and solvent type. In a preferred embodiment, the copolymer (A) has a molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of 1.5 to 5.0. In a more preferred embodiment, 1.7 to 4.0 is obtained, and in a particularly preferred embodiment, one in the range of 2.0 to 3.5 is obtained. When the molecular weight distribution is in the above range, the resulting thermoplastic copolymer tends to be excellent in moldability and can be preferably used.

  Thermoplastic copolymer containing glutaric anhydride units by heating the copolymer (A) in the second step of the present invention, and performing an intramolecular cyclization reaction by (i) dehydration and / or (b) dealcoholization. The method for producing the coalesced is not particularly limited, but is produced by passing through a heated extruder having a vent, in an inert gas atmosphere such as in a nitrogen stream, or in an apparatus that can be heated and devolatilized under vacuum. Is preferred. Among them, when an intramolecular cyclization reaction is carried out by heating in the presence of oxygen, the yellowness tends to deteriorate, so it is preferable to sufficiently substitute the inside of the system with an inert gas such as nitrogen. As a particularly preferred apparatus, for example, a single screw extruder equipped with a “unimelt” type screw, a twin screw, a three screw extruder, a continuous or batch kneader type kneader, etc. can be used. The machine can be preferably used.

  The temperature for the devolatilization by the above method is not particularly limited as long as it is a temperature at which an intramolecular cyclization reaction occurs due to (i) dehydration and / or (b) dealcoholization, but preferably in the range of 180 to 320 ° C. In particular, the range of 200 to 310 ° C is preferable.

  In addition, the time for heating and devolatilization in this case is not particularly limited and can be appropriately set according to the desired copolymer composition, but is usually 1 minute to 60 minutes, preferably 2 minutes to 30 minutes, especially 3 to 3. A range of 20 minutes is preferred. In particular, the ratio of the screw diameter (D) to the screw length (L) of the screw (L / D) in order to ensure sufficient heating time for the intramolecular cyclization reaction to proceed using the extruder. Is preferably 40 or more. When an extruder with a short L / D is used, a large amount of unreacted unsaturated carboxylic acid units remain, so that the reaction proceeds again during the heat molding process, and there is a tendency for silver and bubbles to be seen in the molded product and molding retention. Sometimes the color tends to deteriorate significantly.

  In addition, among the extruders, by using a biaxial / uniaxial composite continuous kneading extruder, there is a tendency to obtain a thermoplastic copolymer having extremely colorless transparency and excellent mechanical properties. it can. Here, the biaxial / single-shaft combined continuous kneading extruder is a biaxial screw portion in which a first shaft and a second shaft in which a screw portion is formed are arranged in parallel in an extruder casing, and a biaxial screw A single screw portion in which a first shaft extended from the screw portion is disposed, and a flow rate adjusting mechanism is provided in a communication portion between the biaxial screw portion and the single screw portion, and the casing communicates with the biaxial screw portion. A twin-screw / single-shaft composite continuous kneading extruder having a raw material supply port and a discharge port communicating with the end of the extended first shaft, and as a commercially available extruder of this type Is an “HTM type extruder” manufactured by CTE. When the copolymer (A) as a raw material is heated in a continuous manner and the cyclization reaction proceeds, due to the progress of the reaction, the melt viscosity increases, and the heat generated by the shearing of the extrusion apparatus increases. There is a tendency for coloring due to thermal decomposition of the molecular main chain to increase. Further, the shear heat generation becomes larger when melt kneading with a twin screw than with a single screw. On the other hand, from the viewpoint of reaction rate, it is preferable to melt and knead with a twin screw. From the above, by using a specific twin-screw / single-screw composite continuous kneading extruder, in the initial reaction stage where the melt viscosity is relatively low, the melt viscosity is secured while ensuring a sufficient reaction speed with a twin screw. In the later stage of the reaction when the temperature is relatively high, heat treatment with a single screw portion that suppresses heat generation by shearing suppresses thermal decomposition of the molecular main chain, so that the heat containing the resulting glutaric anhydride-containing unit is reduced. It is speculated that the plastic copolymer (A) is particularly excellent in color tone and mechanical properties.

  When the copolymer (A) is heated using the extruder, the cylinder temperature of the extruder is preferably set to 200 to 320 ° C, and more preferably set to 220 to 310 ° C.

  Furthermore, in this invention, when heating a copolymer (A) by the said method etc., as a catalyst which accelerates | stimulates the cyclization reaction to glutaric acid anhydride, 1 or more types of an acid, an alkali, and a salt compound may be added. it can. The addition amount is not particularly limited, and is preferably about 0.01 to 1 part by weight per 100 parts by weight of the copolymer (A). There are no particular restrictions on the types of these acids, alkalis, and salt compounds, and examples of the acid catalyst include hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, phosphoric acid, phosphorous acid, phenylphosphonic acid, and methyl phosphate. It is done. Examples of the basic catalyst include metal hydroxides, amines, imines, alkali metal derivatives, alkoxides, ammonium hydroxide salts and the like. Furthermore, examples of the salt-based catalyst include metal acetates, metal stearates, metal carbonates, and the like. However, it is necessary to add in a range where the color possessed by the catalyst does not adversely affect the coloring of the thermoplastic copolymer and the transparency is not lowered. Among them, an alkali metal-containing compound (alkali metal compound) can be preferably used because it exhibits an excellent reaction promoting effect with a relatively small addition amount. Specifically, hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, alkoxide compounds such as sodium methoxide, sodium ethoxide, sodium phenoxide, potassium methoxide, potassium ethoxide, and potassium phenoxide, lithium acetate And organic carboxylates such as sodium acetate, potassium acetate, and sodium stearate. Among them, sodium hydroxide, sodium methoxide, lithium acetate, and sodium acetate can be preferably used.

  The content of the glutaric anhydride unit represented by the general formula (1) in the thermoplastic copolymer (B) of the present invention is not particularly limited, but preferably in 100% by weight of the thermoplastic copolymer. 5 to 50% by weight, more preferably 10 to 50% by weight, still more preferably 25 to 50% by weight, and particularly preferably 30 to 45% by weight.

In addition, an infrared spectrophotometer or a proton nuclear magnetic resonance ( ¹ H-NMR) measuring instrument is generally used for quantification of each component unit in the thermoplastic copolymer of the present invention. In infrared spectroscopy, glutaric anhydride units, absorption of 1800 cm ^-1 and 1760 cm ^-1 are characteristic can be distinguished from unsaturated carboxylic acid units and unsaturated carboxylic acid alkyl ester unit. In the ¹ H-NMR method, for example, in the case of a copolymer consisting of a glutaric anhydride unit, methacrylic acid, and methyl methacrylate, the attribution of the spectrum in dimethyl sulfoxide heavy solvent is 0.5 to 1.5 ppm. Peak of methacrylic acid, methyl methacrylate and glutaric anhydride ring compound α-methyl group hydrogen, 1.6 to 2.1 ppm peak of polymer main chain methylene group hydrogen, 3.5 ppm peak of methacrylic acid Copolymer composition can be determined from hydrogen of carboxylic acid ester of methyl acid (—COOCH ₃ ), a peak of 12.4 ppm and hydrogen of carboxylic acid of methacrylic acid and an integral ratio of the spectrum. In addition to the above, when styrene is contained as another copolymerization component, hydrogen in the aromatic ring of styrene is found at 6.5 to 7.5 ppm, and the copolymer composition is similarly determined from the spectral ratio. can do.

  In addition to the components (i) and (ii), the thermoplastic copolymer of the present invention contains an unsaturated carboxylic acid unit and / or another copolymerizable vinyl monomer unit. Can do.

  In the present invention, the amount of the unsaturated carboxylic acid unit contained in the thermoplastic copolymer is 10% by sufficiently carrying out (i) dehydration and / or (b) dealcoholization reaction of the copolymer (A). % Or less, that is, 0 to 10% by weight, more preferably 0 to 5% by weight. When the unsaturated carboxylic acid unit exceeds 10% by weight, colorless transparency and residence stability tend to be lowered.

  The amount of other copolymerizable vinyl monomer units is preferably 0 to 35% by weight, more preferably 10% by weight or less, that is, 0 to 10% by weight, further preferably 0 to 0% by weight. 5% by weight. In particular, when an aromatic vinyl monomer unit such as styrene is contained, if the content is too large, the colorless transparency, optical isotropy, and chemical resistance tend to decrease.

  The thermoplastic copolymer (B) of the present invention has a weight average molecular weight (hereinafter also referred to as Mw) of preferably 2000 to 1000000, and more preferably 5000 to 500000. In addition, the weight average molecular weight as used in the field of this invention shows the weight average molecular weight in the absolute molecular weight measured by multi-angle light scattering gel permeation chromatography (GPC-MALLS).

  The thermoplastic copolymer (B) of the present invention thus obtained has excellent heat resistance with a glass transition temperature of 120 ° C. or higher, and is preferable in terms of practical heat resistance. Further, in a preferred embodiment, the glass transition temperature has extremely excellent heat resistance of 130 ° C. or higher. Moreover, as an upper limit, it is about 160 degreeC normally. The glass transition temperature here is a glass transition temperature measured at a heating rate of 20 ° C./min using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer).

  Further, the thermoplastic copolymer (B) produced by the production method of the present invention has a yellowness (Yellowness Index) value of 3 or less in a preferred embodiment, and coloring is suppressed, and in a more preferred embodiment, 2 or less. It has extremely high colorless transparency. In the above, the yellowness is a value obtained by measuring the YI value of a 1 mm-thick molded product injection-molded at a glass transition temperature + 140 ° C. according to JIS-K7103. The lower limit of the yellowness is not particularly limited and is preferably as low as possible, but is usually about 1.

  Further, at the time of producing the thermoplastic copolymer (B) of the present invention, hindered phenol-based, benzotriazole-based, benzophenone-based, benzoate-based and cyanoacrylate-based ultraviolet absorbers and Antioxidants, higher fatty acids, acid esters and acid amides, lubricants and plasticizers such as higher alcohols, release agents such as montanic acid and salts thereof, esters thereof, half esters, stearyl alcohol, stearamide and ethylene wax , Anti-coloring agents such as phosphites and hypophosphites, halogen flame retardants, phosphorous and silicone non-halogen flame retardants, nucleating agents, amines, sulfonic acids, polyethers, etc. Additives such as colorants such as inhibitors and pigments may be optionally added. However, it is necessary to add the color within a range in which the color of the additive does not adversely affect the thermoplastic copolymer (B) of the present invention and the transparency does not deteriorate.

  The thermoplastic copolymer (B) produced according to the present invention makes use of its excellent heat resistance, colorless transparency and retention stability, and is used for electrical / electronic parts, automobile parts, mechanical mechanism parts, OA equipment, home appliances. It can be used for various uses such as housings and their parts and general sundries.

  Specific uses of the molded article made of the thermoplastic copolymer (B) produced according to the present invention include, for example, electrical equipment housings, OA equipment housings, various covers, various gears, various cases, sensors, LED lamps. , Connectors, sockets, resistors, relay cases, switches, coil bobbins, capacitors, variable capacitor cases, optical pickups, oscillators, various terminal boards, transformers, plugs, printed wiring boards, tuners, speakers, microphones, headphones, small motors, Electric / electronic parts such as magnetic head base, power module, housing, semiconductor, liquid crystal, FDD carriage, FDD chassis, motor brush holder, parabolic antenna, computer-related parts; VTR parts, TV parts, irons, hair dryers Home, rice cooker parts, microwave oven parts, acoustic parts, audio equipment parts such as audio / laser disc / compact disc, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, word processor parts, etc. Product parts, office computer related parts, telephone related parts, facsimile related parts, copying machine related parts, cleaning jigs, oilless bearings, stern bearings, underwater bearings, various bearings, motor parts, lighters, typewriters, etc. Representative machinery-related parts, microscopes, binoculars, cameras, optical instruments, such as watches, precision machinery-related parts; alternator terminals, alternator connectors, IC regulators, various valves such as exhaust gas valves, fuel-related / exhaust systems / intake Various pipes, air Intake nozzle snorkel, intake manifold, fuel pump, engine coolant joint, carburetor main body, carburetor spacer, exhaust gas sensor, coolant sensor, oil temperature sensor, brake pad wear sensor, throttle position sensor, crankshaft position sensor, air flow Meter, air conditioning thermostat base, heating hot air flow control valve, radiator motor brush holder, water pump impeller, turbine vane, wiper motor related parts, dust distributor, starter switch, starter relay, transmission wire harness, window washer Nozzle, air conditioner panel switch board, coil for fuel related solenoid valve, Examples include a connector for a fuse, a horn terminal, an electrical component insulating plate, a step motor rotor, a lamp socket, a lamp reflector, a lamp housing, a brake piston, a solenoid bobbin, an engine oil filter, and an ignition device case. In addition, because of its excellent transparency and heat resistance, it is used as a component for optical recording / communications, such as imaging equipment, such as cameras, VTRs, projection TVs, viewfinders, filters, prisms, and Fresnel lenses. Various optical equipment (VD, CD, DVD, MD, LD, etc.) substrates, various disc substrate protective films, optical disc player pickup lenses, optical fibers, optical switches, optical connectors, and other information equipment related parts such as liquid crystal displays, flat panel displays, plasmas Display light guide plate, Fresnel lens, polarizing plate, polarizing plate protective film, retardation film, light diffusion film, viewing angle widening film, reflective film, antireflection film, antiglare film, brightness enhancement film, prism sheet, pickup lens , Light guide films for touch panels, covers, etc., as parts related to transportation equipment such as automobiles, tail lamp lenses, head lamp lenses, inner lenses, amber caps, reflectors, extensions, side mirrors, room mirrors, side visors, instrument needles, instrument covers , Glazing typified by window glass, etc. as medical equipment related parts, spectacle lenses, spectacle frames, contact lenses, endoscopes, optical cells for analysis, etc., as building material related parts, lighting windows, road translucent plates, lighting covers It can also be applied to signboards, translucent sound insulation walls, bathtub materials, etc., and is extremely useful for these various applications.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Each measurement and evaluation was performed by the following method.

(1) Weight average molecular weight / molecular weight distribution The obtained copolymer was dissolved in tetrahydrofuran to prepare a measurement sample. Gel permeation chromatograph (pump: model 515, manufactured by Waters, column: TSK-gel-GMHXL, manufactured by Tosoh Corporation) equipped with a DAWN-DSP type multi-angle light scattering photometer (manufactured by Wyatt Technology) using tetrahydrofuran as a solvent. ) Was used to measure the weight average molecular weight (absolute molecular weight) and the number average molecular weight (absolute molecular weight). The molecular weight distribution was calculated by weight average molecular weight (absolute molecular weight) / number average molecular weight (absolute molecular weight).

(2) Composition of each component In heavy dimethyl sulfoxide, ¹ H-NMR was measured at 30 ° C. to determine the composition of each copolymer unit.

(3) Solubility parameter difference (ΔSP value)
“Introduction to Synthetic Resins for Paints”, Kyozo Kitaoka, p23-p31, Kobunshi Kyokukai (1986), Tables 2-8 and 2-9, with the method of Small (a), (b ), The solubility parameter δp of the copolymer (A) and the solubility parameter δs of the organic solvent (B) were calculated, and the absolute value of the difference was determined as the solubility parameter difference.
(A) Solubility parameter δp of copolymer (A)
It calculated by the following formula from the molar fraction Xi of each monomer unit in the copolymer (A) and the solubility parameter δi of each monomer.

δp = Σ (δi × Xi / 100)
(B) Solubility parameter δs of organic solvent (B)
The calculation was performed in the same manner as the method for calculating the solubility parameter δp of the copolymer (A). Further, the solubility parameter δs when the organic solvent (B) is a mixture of two or more types is calculated from the following formula using the molar fraction Xi (%) of each solvent component in the mixed organic solvent and the solubility parameter δi of each solvent component. Calculated by

δp = Σ (δi × Xi / 100)
(4) Solubility The obtained copolymer (A) was added to 100 g of the organic solvent (B) used for the copolymerization, and the solution state was visually observed after stirring for 24 hours at 23 ° C. The weight of the dissolved copolymer (A) was evaluated.

(5) Glass transition temperature (Tg)
Using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer), the measurement was performed at a temperature increase rate of 20 ° C./min in a nitrogen atmosphere.

(6) Transparency (total light transmittance, haze)
The obtained thermoplastic copolymer was injection-molded at a glass transition temperature of + 140 ° C., and the total light transmittance (%) and haze (haze) (%) at 23 ° C. of the obtained 1 mm-thick molded product Transparency was evaluated by measuring using a direct reading haze meter manufactured by Seiki Co., Ltd.

(7) Yellowness Index
The obtained thermoplastic copolymer was injection molded at a glass transition temperature of + 140 ° C., and the YI value of the obtained 1 mm-thick molded product was measured using an SM color computer (manufactured by Suga Test Instruments Co., Ltd.) according to JIS-K7103. did.

(8) Number of foreign substances The obtained thermoplastic copolymer pellets were dissolved in methyl ethyl ketone at a concentration of 25% by weight with stirring at room temperature for 24 hours, and the obtained thermoplastic copolymer solution was cast into a glass plate shape. Thereafter, a drying process was performed at 50 ° C. for 20 minutes, and then at 80 ° C. for 30 minutes, thereby forming a film having a thickness of 100 ± 5 μm. This film was observed with an optical microscope, and the number of foreign matters of 20 μm or more per 1 mm square unit area was counted. This was observed at 10 points at random per sample and the count of the number of foreign matters was repeated, and the average value was evaluated as the number of foreign matters per 1 mm square unit area (pieces / mm ² ).

(9) Gas generation amount during residence The obtained thermoplastic copolymer pellets were pre-dried at 80 ° C. for 12 hours, and the weight before and after being heat-treated in a heating furnace adjusted to 280 ° C. for 15 minutes was measured. The weight reduction rate calculated by the following equation was evaluated as the amount of gas generated during residence.
Weight reduction rate (%) = [(weight before heat treatment−weight after heat treatment) / weight before heat treatment] × 100.

Reference Example (1) Synthesis of copolymer (A) (first step)
(A-1): Precipitation polymerization method The following mixed substances are supplied to a stainless steel autoclave having a capacity of 20 liters and equipped with a baffle and a foudra type stirring blade, and nitrogen is added to the system at 10 L / min while stirring at 250 rpm. Gas was bubbled for 15 minutes. Next, nitrogen gas was flowed at a flow rate of 5 L / min, and the reaction system was heated to 80 ° C. while stirring. When the internal temperature reached 80 ° C., the polymerization was started. The internal temperature was maintained at 80 ° C. for 90 minutes, and after raising the temperature to 95 ° C., the polymerization was further continued for 90 minutes to complete the polymerization. The reaction system was cooled to room temperature, and the resulting slurry was treated with a centrifuge “LAC-21” (product of Matsumoto Machine Sales Co., Ltd.) for 2 hours while flowing nitrogen gas, and copolymer (A-1) And the organic solvent were separated. The polymer recovery rate by the centrifuge processing was almost 100%. The reslurry washing with the polymerization solvent was repeated three times, followed by drying at 80 ° C. for 12 hours to obtain a powdery copolymer (A-1). The copolymer (A-1) had a polymerization rate of 76% and a weight average molecular weight of 120,000.
Methacrylic acid 25 parts by weight Methyl methacrylate 75 parts by weight n-heptane 900 parts by weight 2,2′-azobis-2,4-dimethylvaleronitrile 0.5 part by weight.

(A-2): Precipitation polymerization method A copolymer (A-2) was obtained at a polymerization rate of 73% by the same production method as (A-1) except that the polymerization solvent was changed to butyl acetate. The weight average molecular weight was 120,000.
Methacrylic acid 25 parts by weight Methyl methacrylate 75 parts by weight Butyl acetate 900 parts by weight 2,2'-azobis-2,4-dimethylvaleronitrile 0.5 part by weight.

(A-3): Precipitation polymerization method The copolymer (A-2) was converted to 75% by the same production method as (A-1) except that the polymerization solvent was changed to a mixture of n-heptane and butyl acetate. Obtained by polymerization rate. The weight average molecular weight was 120,000.
Methacrylic acid 25 parts by weight Methyl methacrylate 75 parts by weight n-Heptane 225 parts by weight Butyl acetate 675 parts by weight 2,2′-azobis-2,4-dimethylvaleronitrile 0.5 parts by weight

(A-4): Precipitation polymerization method A mixture of the following (a) is supplied to a stainless steel autoclave having a capacity of 20 liters and equipped with a baffle and a foudra-type stirring blade, and the system is mixed with 10 L while stirring at 250 rpm. Bubbling with nitrogen gas for 15 minutes per minute. Next, nitrogen gas was flowed at a flow rate of 5 L / min, and the reaction system was heated to 95 ° C. while stirring. The following mixed substances (b) were sequentially added in 180 minutes, and after maintaining for another 60 minutes, the polymerization was terminated. The reaction system was cooled to room temperature, and the slurry was centrifuged and washed with a polymerization solvent three times, followed by drying at 80 ° C. for 12 hours to obtain a powdery copolymer (A-1). The polymerization rate of this copolymer (A-1) was 77%. The weight average molecular weight was 120,000.
Mixed substance (I):
Methacrylic acid 2 parts by weight Methyl methacrylate 8 parts by weight n-Heptane 25 parts by weight Butyl acetate 75 parts by weight Mixed substance (b):
Methacrylic acid 22 parts by weight Methyl methacrylate 68 parts by weight n-heptane 200 parts by weight Butyl acetate 600 parts by weight 2,2′-azobis-2,4-dimethylvaleronitrile 0.5 part by weight.

(A-5): Precipitation polymerization method The copolymer (A-2) was polymerized by the same production method as (A-1) except that the polymerization solvent was changed to benzene. However, since a solvent-insoluble swelling / gel-like product was formed from the initial stage of polymerization and stirring became impossible, the polymerization rate could not be increased and the polymerization rate was 16%.

Methacrylic acid 25 parts by weight Methyl methacrylate 75 parts by weight Benzene 900 parts by weight.

(A-6): Suspension polymerization method A methyl methacrylate / acrylamide copolymer suspension (prepared by the following method) was placed in a stainless steel autoclave having a capacity of 5 liters and equipped with a baffle and a foudra-type stirring blade. 20 parts by weight of methyl acid, 80 parts by weight of acrylamide, 0.3 part by weight of potassium persulfate and 1500 parts by weight of ion-exchanged water are charged into the reactor and maintained at 70 ° C. while replacing the reactor with nitrogen gas. Continue until the polymer is completely converted to polymer, and obtain 0.05 parts of aqueous solution of methyl acrylate and acrylamide copolymer (using the resulting aqueous solution as a suspending agent) to 165 parts of ion-exchanged water. The dissolved solution was supplied and stirred at 400 rpm, and the system was replaced with nitrogen gas. Next, the following mixed substances were added while stirring the reaction system, and the temperature was raised to 70 ° C. The time when the internal temperature reached 70 ° C. was set as the start of polymerization, and kept for 180 minutes to complete the polymerization. Thereafter, the reaction system was cooled, the polymer was separated, washed and dried according to the usual method to obtain a bead-shaped copolymer (A-6). The polymerization rate of this copolymer (A-6) was 98%, and the weight average molecular weight was 130,000.
Methacrylic acid 27 parts by weight Methyl methacrylate 73 parts by weight n-dodecyl mercaptan 0.4 part by weight 2,2′-azobisisobutyronitrile 0.2 part by weight.

(A-7): Solution polymerization method The following mixed substances are supplied to a stainless steel autoclave having a capacity of 20 liters and equipped with baffles and foudra-type stirring blades, and the system is mixed with nitrogen at 10 L / min while stirring at 250 rpm. Gas was bubbled for 15 minutes. Next, nitrogen gas was flowed at a flow rate of 5 L / min, and the reaction system was heated to 80 ° C. while stirring. When the internal temperature reached 80 ° C., the polymerization was started. The internal temperature was maintained at 80 ° C. for 90 minutes, and after the temperature was raised to 90 ° C., the polymerization was further continued for 90 minutes to complete the polymerization. The reaction system was cooled to room temperature to obtain a polymer solution (A-6-1) having no insoluble precipitate. The polymer solution (A-7-1) was dropped into a large amount of ion-exchanged water, and the powder obtained was dried at 80 ° C., but 72 hours were required to completely remove ethylene glycol monoethyl ether as a polymerization solvent. It cost. The weight average molecular weight of the obtained copolymer (A-7-2) was 100,000.
Methacrylic acid 27 parts by weight Methyl methacrylate 73 parts by weight Ethylene glycol monoethyl ether 200 parts by weight 2,2′-azobis-2,4-dimethylvaleronitrile 0.3 parts by weight

  Table 4 shows each component composition and copolymerization result of the copolymer (A) obtained in Reference Example (1).

Examples 1-5 and Comparative Examples 1-6, Production of Thermoplastic Copolymer (B) (Second Step)
(B-1) to (B-7)
To 100 parts by weight of the copolymer (A) obtained in Reference Example (1), 0.2 part by weight of lithium acetate as a catalyst was blended, and a 38 mmφ biaxial / uniaxial composite continuous kneading extruder (HTM38 (CTE L / D = 47.5, vent part: 2 places) Purging nitrogen from the hopper part at an amount of 10 L / min, screw rotation speed 75 rpm, raw material supply rate 10 kg / h, cylinder temperature An intramolecular cyclization reaction was performed at 290 ° C. to obtain a pellet-like thermoplastic copolymer <B> ((B-1) to (B-7)).

(B-8): Example 5
To 100 parts by weight of the copolymer (A-4) obtained in Reference Example (1), 0.2 part by weight of lithium acetate was blended, and this was mixed with a 44 mmφ twin screw extruder (TEX-44 (Nippon Steel Works). L / D = 28.0, vent part: 3 locations), while purging nitrogen from the hopper at a rate of 10 L / min, screw rotation speed 75 rpm, raw material supply rate 5 kg / h, cylinder temperature An intramolecular cyclization reaction was performed at 280 ° C. to obtain a pellet-shaped thermoplastic copolymer (B-8).

(B-9): Comparative Example 4
The polymer solution (A-6-1) obtained at the time of manufacturing the copolymer <A-7-2> of Reference Example (1) was directly added to a 30 mmφ twin-screw extruder (TEX-30 (manufactured by Nippon Steel Works, Ltd., L /D=44.0, vent part: 5 points) While purging nitrogen from the hopper part at an amount of 10 L / min, the screw rotation speed is 75 rpm, the raw material polymer solution (A-7-1) supply amount At 5 kg / h and a cylinder temperature of 280 ° C., degassing of the solvent contained in a large amount in the polymer solution (A-7-1) and intramolecular cyclization reaction were simultaneously performed, and a pellet-shaped thermoplastic copolymer (B- However, 5% by weight of the solvent remained in <B-9>.
(B-10): Comparative Example 5
The above (B-9) was again set to a screw rotation speed of 75 rpm and a cylinder temperature of 280 ° C., and a 30 mmφ twin screw extruder (TEX-30 (manufactured by Nippon Steel Works, L / D = 44.0, vent part: 5 places ), While purging nitrogen from the hopper at an amount of 10 L / min, the raw material was supplied at a rate of 5 kg / h to obtain a pellet-shaped thermoplastic copolymer <B-10> from which the residual solvent was completely removed. However, (B-10) was remarkably yellowed.
(B-11): Comparative Example 6
The polymer solution (A-7-1) obtained at the time of production of the copolymer <A-7-2> of Reference Example (1) was directly supplied to a tank equipped with a vacuum deaeration device, and the solution was 20 Torr at 255 ° C. And a deaeration of a solvent contained in a large amount in the polymer solution (A-7-1) and an intramolecular cyclization reaction were simultaneously performed to obtain a thermoplastic copolymer (B-11).

Next, the pellets were dried at 100 ° C. for 8 hours, and each copolymer component composition and various characteristics evaluation results determined by ¹ H-NMR are shown in Table 5.

  From Examples 1 to 5 and Comparative Examples 1 to 6, in the production method of the present invention, in the first step, the monomer mixture as a raw material is dissolved, and the copolymer (A) is not dissolved in a specific organic solvent. It is possible to produce a thermoplastic copolymer (B) that is excellent in colorless transparency and particularly has few foreign matters, while having high heat resistance and heat stability with a small amount of generated gas even during residence. I understand that I can do it.

  On the other hand, when the polymerization is carried out by a method outside the scope of the present invention, it can be seen that the color tone of the thermoplastic copolymer after heat treatment and the number of foreign substances are inferior in any other conditions.

Claims (9)

(I) a step of producing a copolymer (A) containing an unsaturated carboxylic acid alkyl ester unit and (ii) an unsaturated carboxylic acid unit (first step), followed by heating the copolymer (A) (Iii) a glutaric anhydride unit represented by the following general formula (1) by a step (second step) of performing (i) dehydration and / or (b) an intramolecular cyclization reaction by dealcoholization reaction And (i) when producing the thermoplastic copolymer (B) containing an unsaturated carboxylic acid alkyl ester unit, as the first step, an unsaturated organic solvent that does not contain an aromatic group and is a raw material The monomer mixture containing the carboxylic acid alkyl ester monomer and the unsaturated carboxylic acid monomer is dissolved, and in the organic solvent (C) in which the solubility of the copolymer (A) is 1 g / 100 g or less, Including the step of copolymerizing the monomer mixture. Method for producing a thermoplastic copolymer, characterized in that.

(However, R < ¹ >, R < ² > represents the same or different hydrogen atom or a C1-C5 alkyl group.) The copolymerization of the monomer mixture in the first step is performed under the condition that the absolute value (ΔSP) of the difference between the solubility parameter of the copolymer (A) and the solubility parameter of the organic solvent (C) is 1.0 or more. The method for producing a thermoplastic copolymer according to claim 1, wherein In the copolymerization of the monomer mixture in the first step, the absolute value (ΔSP) of the difference between the solubility parameter of the copolymer (A) and the solubility parameter of the organic solvent (C) is 1.5 to 1.7. 2. The process for producing a thermoplastic copolymer according to claim 1, wherein the process is carried out under certain conditions. 4. The thermoplastic copolymer according to claim 1, wherein the organic solvent (C) used in the first step is one or more selected from aliphatic hydrocarbons, carboxylic acid esters, and ketones. Manufacturing method. The method for producing a thermoplastic copolymer according to any one of claims 1 to 4, wherein the organic solvent (C) used in the first step is a mixture of an aliphatic hydrocarbon and a carboxylic acid ester. 6. The heat according to claim 5, wherein the organic solvent (C) used in the first step is a mixture of an aliphatic hydrocarbon and a carboxylic acid ester, and the weight ratio thereof is 5/95 to 70/30. A method for producing a plastic copolymer. The method for producing a thermoplastic copolymer according to any one of claims 1 to 6, wherein the copolymer (A) contains (ii) 15 to 50% by weight of an unsaturated carboxylic acid unit. The method for producing a thermoplastic copolymer according to any one of claims 1 to 7, wherein the heat treatment in the second step is performed using a continuous kneading extruder. In the continuous kneading and extruding apparatus, a single shaft in which a first shaft extending from a biaxial screw portion and a biaxial screw portion in which a first shaft and a second shaft forming a screw portion are arranged in parallel are arranged in a casing. A shaft screw portion, and a communication portion between the biaxial screw portion and the monoaxial screw portion is provided with a flow rate adjusting mechanism, the casing is provided with a raw material supply port communicating with the biaxial screw portion, and the extended first 9. The method for producing a thermoplastic copolymer according to claim 8, which is a biaxial / single-shaft composite continuous kneading and extruding apparatus having a discharge port communicating with an end portion of one axis.