JP6309806B2 - Method for producing polymer - Google Patents

Description

  The present invention relates to a thermoplastic resin composition that can be suitably used, for example, as an optical material.

  α-Hydroxyalkyl acrylates have both polymerization reactivity due to double bond sites and reactivity due to hydroxyl groups, and are widely used as monomer raw materials for forming polymers. For example, after copolymerization with another monomer having a carboxylic acid group at a double bond site, a carboxylic acid group derived from another monomer and a hydroxyl group are condensed in the molecule, thereby causing a ring in the molecule. A polymer with an introduced structure is obtained. Such polymers have high heat resistance and excellent transparency, and are useful as optical materials.

  Various production methods for α-hydroxyalkyl acrylate have been reported so far, but as an industrial and practical method, α, β-unsaturated carboxylic acid esters and aldehydes are combined with tertiary amine compounds. A method of reacting in the presence (a so-called Morita-Baylis-Hillman reaction) is effective.

  By the way, when a polymerization reaction is carried out using α-hydroxyalkyl acrylate generated by Morita-Baylis-Hillman reaction or the like, a large amount of foreign matter is contained in the resulting resin, and its use as an optical material or the like is limited. There was a thing.

  Therefore, as a method for reducing such foreign matter in the resin, a method has been proposed in which the resin is melted under predetermined conditions, and filtered and purified using a polymer filter (Patent Document 1). However, even if such a method is used to purify a resin obtained using α-hydroxyalkyl acrylate as a monomer raw material, very fine foreign matters (for example, less than 20 μm in major axis) may not be completely removed. In order to use it as an optical material or the like, it is necessary to reduce such fine foreign matter to an extremely small amount.

  In general, it is considered that fine foreign substances can be removed by increasing the filtration accuracy of the polymer filter according to the size, but the present inventors have examined that even if the filtration accuracy is high ( Even if a polymer filter was used, the number of fine foreign matters contained in the resin obtained using α-hydroxyalkyl acrylate as a monomer raw material could not be reduced.

JP 2012-25968 A

  The present invention has been made in view of the circumstances as described above, and the object thereof is a thermoplastic resin composition that can be used as an optical material or the like because the content of fine foreign matters is extremely low. Is to provide.

  The inventors of the present invention have made extensive studies to solve the above problems. First, when α-hydroxyalkyl acrylate is hydrolyzed with alkali, a dimer is produced as a by-product, and the dimer produces a polymer. The dimer is contained in α-hydroxyalkyl acrylate based on the knowledge that the problem of gelation is caused (paragraphs 0011 and 0012 of JP-A-10-218834). The gelled product was considered to be a cause of fine foreign matters, and an attempt was made to reduce fine foreign matters by removing dimers in α-hydroxyalkyl acrylate. However, even if the dimer in α-hydroxyalkyl acrylate was removed, fine foreign matters could not be sufficiently reduced (see Comparative Example 1 described later). Therefore, as a result of further research, the present inventors have sometimes referred to a specific component (hereinafter referred to as “specific high-boiling impurity”) that is detected at a predetermined retention time when α-hydroxyalkyl acrylate is analyzed by gas chromatography. ) Has a great influence on the appearance of fine foreign matter, and if the content is reduced, it is found that the fine foreign matter in the resin obtained using the α-hydroxyalkyl acrylate can be remarkably reduced. The present invention has been completed.

That is, the thermoplastic resin composition according to the present invention is a thermoplastic resin composition containing at least one of a polymer containing an α-hydroxyalkyl acrylate unit or a polymer having a cyclic structure introduced into the main chain of the polymer. The α-hydroxyalkyl acrylate has a high boiling point impurity content (C _hbp ) determined by the following formula of 0.6% by mass or less.
_{C hbp = (A hbp / A} std) × F RHMA × (W std / W total) × 100
_{(Wherein, A hbp, A std, F} RHMA, W std, none of the W _total, by gas chromatography using a capillary column which molecular weight is 20,000, bonded-polyethylene glycol fillers, alpha-hydroxyalkyl This is a value obtained by analyzing a sample containing acrylate and an internal standard substance, of which A _std indicates the peak area of the internal standard substance, and A _hbp is a retention time of α-hydroxyalkyl acrylate of 1. Of the peaks whose relative retention time is 0.90 to 1.30, the total area of the peaks excluding α-hydroxyalkyl acrylate is shown, but polymerization is performed in the range of relative retention time 0.90 to 1.30. if it contains peaks of inhibitor, the a _hbp, the area of the peak of the polymerization inhibitor does not comprise .F _RHMA is alpha-hydroxyalkyl a It is the slope of the calibration curve showing the relationship between the mass ratio of acrylate and internal standard substance and the ratio of these peak areas, W _std indicates the mass of the internal standard substance in the implanted sample, and W _total indicates the mass in the implanted sample. (The apparent mass of the α-hydroxyalkyl acrylate is shown.)

  In the thermoplastic resin composition of the present invention, the content of ether dimer, which is a dehydration dimerization impurity, contained in the α-hydroxyalkyl acrylate is preferably 0.50% by mass or less.

  Another thermoplastic resin composition according to the present invention is a thermoplastic resin composition containing at least one of a polymer containing an α-hydroxyalkyl acrylate unit or a polymer having a cyclic structure introduced into the main chain of the polymer. The number of foreign matters having a major axis of 5 μm or more and less than 20 μm is 100 / g or less.

  The thermoplastic resin composition of the present invention is preferably used as an optical material.

  According to the present invention, an α-hydroxyalkyl acrylate having a specific high-boiling-point impurity content of a predetermined amount or less is used as a raw material monomer, so that a thermoplastic resin composition having an extremely small content of fine foreign matters is provided. Such a thermoplastic resin composition can be suitably used as an optical material or the like.

FIG. 1 is an example of a gas chromatography analysis chart of methyl α-hydroxymethyl acrylate used in the present invention. FIG. 2 is an enlarged view of the gas chromatography analysis chart of FIG.

In the thermoplastic resin composition of the present invention, a polymer using α-hydroxyalkyl acrylate (hereinafter sometimes referred to as “RHMA”) as a raw material monomer, or a ring structure is introduced into the main chain of the polymer. Including at least one of polymers (hereinafter, these polymers may be collectively referred to as "RHMA-derived polymer"), and the content of the specific high-boiling impurities contained in the α-hydroxyalkyl acrylate is It is characterized in that the amount is less than a predetermined amount, or the amount of foreign matter having a major axis of 5 μm or more and less than 20 μm (hereinafter also referred to as “fine foreign matter”) is not more than a predetermined amount.
Below, predetermined RHMA in this invention is demonstrated first, Then, the resin composition containing this RHMA origin polymer using this and this RHMA origin polymer is demonstrated.

1. RHMA
1.1. Structure of RHMA α-hydroxyalkyl acrylate (RHMA) in the present invention is represented by the following general formula (1).

(In the general formula (1), R ¹ represents an organic residue, and R ² represents a hydrogen atom or an organic residue.)

In the general formula (1), the organic residue which is an example of R ¹ is a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, a hydroxyalkyl group having 1 to 8 carbon atoms, or an aryl group. Is mentioned. Among these, a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms (for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, A hexyl group, a 2-ethylhexyl group or a cyclohexyl group) and an aryl group (for example, a phenyl group) are preferred.

In the general formula (1), examples of the organic residue as an example of R ² include the same organic residues as those of R ¹ described above, and among these, a lower alkyl group having 1 to 2 carbon atoms. (Methyl group or ethyl group) is preferred.

  Specific examples of the α-hydroxyalkyl acrylate represented by the general formula (1) include, for example, methyl α-hydroxymethyl acrylate, ethyl α-hydroxymethyl acrylate, propyl α-hydroxymethyl acrylate, α-hydroxymethyl. Isopropyl acrylate, butyl α-hydroxymethyl acrylate, isobutyl α-hydroxymethyl acrylate, tert-butyl α-hydroxymethyl acrylate, pentyl α-hydroxymethyl acrylate, hexyl α-hydroxymethyl acrylate, α-hydroxymethyl 2-ethylhexyl acrylate, phenyl α-hydroxymethyl acrylate, benzyl α-hydroxymethyl acrylate, methyl α- (1-hydroxyethyl) acrylate, ethyl α- (1-hydroxyethyl) acrylate, α- (1 − Dorokishiechiru) butyl acrylate, alpha-(1-hydroxyethyl), and 2-ethylhexyl acrylate and the like. Among these, methyl α-hydroxymethyl acrylate is particularly preferable. These may be only one type or two or more types.

1.2. Impurity amount in _{RHMA In RHMA} in the present invention, it is important that the high boiling point impurity content (C _hbp ) obtained by the following formula is 0.6% by mass or less.
_{C hbp = (A hbp / A} std) × F RHMA × (W std / W total) × 100
_{(Wherein, A hbp, A std, F} RHMA, W std, none of the W _total, by gas chromatography using a capillary column which molecular weight is 20,000, bonded-polyethylene glycol fillers, alpha-hydroxyalkyl This is a value obtained by analyzing a sample containing acrylate and an internal standard substance, of which A _std indicates the peak area of the internal standard substance, and A _hbp is a retention time of α-hydroxyalkyl acrylate of 1. Of the peaks whose relative retention time is 0.90 to 1.30, the total area of the peaks excluding α-hydroxyalkyl acrylate is shown, but polymerization is performed in the range of relative retention time 0.90 to 1.30. if it contains peaks of inhibitor, the a _hbp, the area of the peak of the polymerization inhibitor does not comprise .F _RHMA is alpha-hydroxyalkyl a It is the slope of the calibration curve showing the relationship between the mass ratio of acrylate and internal standard substance and the ratio of these peak areas, W _std indicates the mass of the internal standard substance in the implanted sample, and W _total indicates the mass in the implanted sample. (The apparent mass of the α-hydroxyalkyl acrylate is shown.)

The RHMA in the present invention can be obtained, for example, by a synthesis method described later, but usually contains various impurities such as by-products during synthesis. Among these impurities, a specific high boiling point impurity (that is, detected as a peak having a relative retention time of 0.90 to 1.30 when the retention time of α-hydroxyalkyl acrylate is 1 in the gas chromatography analysis) The thermoplastic resin composition of the present invention has a very small content of fine foreign substances by _setting the content (C _hbp ) of the substance to be a substance other than _RHMA and polymerization inhibitor to 0.6 mass% or less. It will be a thing. C _hbp is preferably 0.5% by mass or less, more preferably 0.4% by mass or less.

The content (C _hbp ) of the specific high-boiling impurity is determined by an internal standard method using a calibration curve of α-hydroxyalkyl acrylate by the gas chromatography analysis. The calibration curve of α-hydroxyalkyl acrylate is a gas chromatographic analysis of a plurality of samples with different mass ratios of α-hydroxyalkyl acrylate and internal standard substance, and the vertical axis indicates “mass of α-hydroxyalkyl acrylate”. / Mass of internal standard substance "and regression line when" peak area of α-hydroxyalkyl acrylate / peak area of internal standard substance "is plotted on the horizontal axis. F _RHMA in the above formula is the slope of this regression line (calibration curve).

  As the internal standard substance, any substance may be used as long as it is detected as a peak that does not overlap with all peaks detected in the gas chromatographic analysis of RHMA, and may be appropriately determined by a known method. For example, relative to RHMA An aliphatic alcohol (for example, an alkoxy group-substituted aliphatic alcohol) having a retention time in the range of about 0.50 to 0.75 may be used. As such an internal standard substance, for example, when RHMA is methyl α-hydroxymethyl acrylate, 2-methoxyethanol is preferably used.

A _hbp in the above formula excludes α-hydroxyalkyl acrylate and a polymerization inhibitor from the peak where the relative retention time is 0.90 to 1.30 when the retention time of α-hydroxyalkyl acrylate is 1. The total area of the peaks. For example, when RHMA is methyl α-hydroxymethyl acrylate, a chart as shown in FIG. 1 is obtained. In this chart, the retention time of 12.178 minutes is detected for methyl α-hydroxymethyl acrylate. It is a peak. At this time, when the peak retention time (12.178 minutes) of this methyl α-hydroxymethyl acrylate is 1, the range in which the relative retention time is 0.90 to 1.30 is the retention time 10 in FIG. The range is from 9602 minutes (12.178 × 0.9) to 15.8314 minutes (12.178 × 1.30).

  In the present invention, when the peak of the polymerization inhibitor is included in the range of the relative retention time 0.90 to 1.30, the peak area of the polymerization inhibitor should not be included in the total area and the total area. And Examples of the polymerization inhibitor that can be contained in RHMA include those described later in “1.3. Method of synthesizing RHMA”, but are not limited thereto, and are known as polymerization inhibitors. Includes all substances.

W _std in the above formula is the mass of the internal standard substance in the implanted sample, W _total is the apparent mass of the α-hydroxyalkyl acrylate in the implanted sample, and these are the internal standard substance and α at the time of sample preparation. -It can obtain | require from each usage-amount (weighing amount) of a hydroxyalkyl acrylate, the dilution rate of the implantation | striking sample prepared from it, and the actual implantation amount. Here, the apparent mass of α-hydroxyalkyl acrylate is a mass obtained by ignoring impurities contained in α-hydroxyalkyl acrylate and replacing the weighed amount at the time of sample preparation with the amount of α-hydroxyalkyl acrylate as it is.

  In the gas chromatography analysis, chemically bonded polyethylene glycol having a molecular weight of 20,000 is used as a filler. As such a filler, for example, “SUPELCOWAX (registered trademark) 10” manufactured by Sigma-Aldrich can be used.

  When performing the gas chromatography analysis, a column having a capillary inner diameter of 0.25 mm and a length of 10 m (preferably a polar column) is used, and the column temperature is maintained at 40 ° C. for 3 minutes, and then the heating rate is 15 The temperature is raised at a rate of ° C / min. Usually, after the column temperature reaches 230 ° C., the measurement may be terminated when the column temperature is maintained for 10 minutes.

  In performing the gas chromatography analysis, the injection amount of the sample is adjusted so that the peak area attributed to RHMA to be detected falls within a range of 5 million to 50 million (preferably 10 million to 30 million). It is preferable. As long as the peak area of RHMA falls within this range, the peak of the specific high-boiling impurity is appropriately detected.

Other conditions in the gas chromatographic analysis may be, for example, as in the examples described later.
When obtaining each peak area in the gas chromatography analysis, a straight line connecting the start point and end point of each peak is defined as an (approximate) baseline, and the area surrounded by the (approximate) baseline and each peak. Is calculated. Specifically, in FIG. 2 in which the chart of FIG. 1 is enlarged, for a peak that does not overlap with other peaks such as a peak detected at a retention time of about 11.7 minutes, the baseline is set to the peak start point ( Since it can be regarded as a line connecting an end point (indicated by a downward arrow (hereinafter the same)) indicated by an upward arrow (hereinafter the same), waveform processing may be performed by dividing the baseline. For peaks that overlap with other peaks (for example, RHMA) such as peaks detected at a retention time of 12.25 minutes to 13.25 minutes, tailing processing is performed and waveform processing is performed, so that the start point and end point are processed. What is necessary is just to obtain | require an area for the line which connects a point as an approximate base line.

In order to control the high boiling point impurity content (C _hbp ) in the _RHMA within the above range, for example, _RHMA is purified by distillation, the number of theoretical plates at this time is increased, and the conditions for dividing impurities are strict. What is necessary is just to raise the purity of RHMA. When purifying in a distillation column, for example, it is preferable to set the maximum temperature reached at the bottom of the distillation column to be low. In the case of methyl α-hydroxymethyl acrylate, it is preferably 140 ° C. or lower, more preferably 130 ° C. or lower, and still more preferably. It is recommended that the temperature be about 120 ° C or lower. In addition, if RHMA is purified in this way, the content of the ether dimer described later can be simultaneously controlled within a predetermined range.

  RHMA in the present invention preferably has an ether dimer content of 0.50% by mass or less, more preferably 0.35% by mass or less, and still more preferably 0.20% by mass or less. Particularly preferred is 0.10% by mass or less, particularly preferred is 0.01% by mass, and most preferred is 0% by mass. Here, the ether dimer is a dimer in which the hydroxyl groups of two RHMAs are condensed to form an ether bond, and is represented by the following general formula (2).

(In general formula (2), R ¹ and R ² have the same meanings as in general formula (1).)
When the content of the ether dimer is within the above range, the content of fine foreign matters contained in the thermoplastic resin composition of the present invention can be further reduced.

The ether dimer content (C _dimer ) can be determined by the following formula according to an internal standard method using a calibration curve of α-hydroxyalkyl acrylate by the analysis by gas chromatography. That is, in the present invention, the content of ether dimer is determined as a content converted to RHMA.
C _dimer = (A _dimer / A _std ) × F _RHMA × (W _std / W _total ) × 100
(In the formula, A _dimer represents the peak area of the ether dimer, and A _std , F _RHMA , W _std , and W _total are all synonymous with the above-described formula for calculating _Chbp .)
In the gas chromatography analysis, the ether dimer is usually detected within the range of the relative retention time 0.90 to 1.30.

  In the present invention, the purity of RHMA, that is, the content of pure α-hydroxyalkyl acrylate is preferably 99.0% by mass or more, more preferably 99.3% by mass or more, and further preferably 99.5% by mass or more. The purity of RHMA can be determined by an internal standard method using an RHMA calibration curve by the gas chromatography described above.

1.3. Method for synthesizing RHMA The method for synthesizing RHMA in the present invention is not particularly limited, and a known organic synthesis method can be employed as appropriate. However, industrially, α, β-unsaturated carboxylic acid ester is used. A method using a Morita-Baylis-Hilman reaction is preferred in which aldehydes and aldehydes are reacted in the presence of a tertiary amine compound as a catalyst.

  Examples of the α, β-unsaturated carboxylic acid esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, Acrylic acid alkyl esters such as n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate; cycloalkyl acrylates such as cyclopentyl acrylate, cyclohexyl acrylate; phenyl acrylate Acrylic acid esters such as o-methoxyphenyl acrylate, p-methoxyphenyl acrylate, p-nitrophenyl acrylate, p-methylphenyl acrylate, p-t-butylphenyl acrylate, and the like; Examples include stealth. Of these acrylic acid esters, methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are particularly suitable.

  Examples of the aldehydes include formaldehyde such as 20 to 50% aqueous solution of formaldehyde, paraformaldehyde, dioxane, and trioxane.

  The use amount of the α, β-unsaturated carboxylic acid esters is preferably such that α, β-unsaturated carboxylic acid esters / aldehydes (molar ratio) is 0.5 to 10, more preferably Preferably it is 0.8-8, More preferably, it is 1-8.

  Examples of the tertiary amine compound include trialkylamines such as trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine; N, N-dimethylethylamine, N, N-dimethylpropylamine, N, N-dimethyl. N, N-dimethylalkylamines such as isopropylamine, N, N-dimethylbutylamine, N, N-dimethylisobutylamine, N, N-dimethyl-t-butylamine, N, N-dimethyl (trimethylsilyl) amine; N, N N, N-diethylalkylamines such as diethylmethylamine, N, N-diethylpropylamine, N, N-diethylisopropylamine; 1,4-diazabicyclo [2,2,2] octane (DABCO), 1-azabicyclo [2,2,2] octane-3-ol, etc. Cyclic amine; and the like. These tertiary amine compounds may be used alone or in combination of two or more. Of these tertiary amines, compounds having a relatively high solubility in water are preferred, and N-methylalkylamines (N-methylbenzene) having a boiling point of 100 ° C. or less at normal pressure and having at least one N-methyl group. Methyl compound) is more preferable, and N, N-dimethylalkylamine having a boiling point at normal pressure of 100 ° C. or less and having at least two N-methyl groups is more preferable. Particularly preferred is trimethylamine. In addition, cyclic amines such as 1,4-diazabicyclo [2,2,2] octane (DABCO) and 1-azabicyclo [2,2,2] octane-3-ol are also preferable.

  The tertiary amine compound can be used in various states such as liquid and gaseous, but is preferably used as a 5 to 80% by mass aqueous solution, and preferably used as a 20 to 60% by mass aqueous solution. preferable. By using the catalyst in the form of an aqueous solution, handling at the start of the reaction and at the time of the reaction is facilitated, and handling when the catalyst is recovered and reused after the completion of the reaction is facilitated.

  The amount of the tertiary amine compound used is not particularly limited, but is preferably used so that the tertiary amine compound / aldehydes (molar ratio) is 0.05 to 2, more preferably It is 0.05-1 and more preferably is 0.07-0.9.

  In the reaction for synthesizing the RHMA, water is usually preferably used as a solvent, but an organic solvent can be used as necessary. The organic solvent is not particularly limited as long as it is a compound that dissolves the substrate and tertiary amine compound used in the reaction and is inert to the reaction. When water is used as the solvent, the amount of water is preferably 0.001% by mass or more and 60% by mass or less, more preferably 0.005% by mass or more and 50% by mass or less, based on the total amount of the reaction solution. More preferably, it is 0.01 mass% or more and 40 mass% or less.

  When synthesizing the RHMA, the α, β-unsaturated carboxylic acid ester as the reaction raw material and the product RHMA have a property of being easily polymerized. Therefore, in order to suppress polymerization during the reaction, It is preferable to add a polymerization inhibitor alone or in combination with molecular oxygen to the reaction system.

  The polymerization inhibitor is not particularly limited, and examples thereof include phosphoric acid, trimethyl phosphate, alkyl phosphates such as triethyl phosphate and tributyl phosphate, aryl phosphates such as diphenyl phosphate, trimethyl phosphite, and phosphorous acid. Phosphites such as triethyl phosphate, triphenyl phosphite, phosphines such as trimethylphosphine, triethylphosphine, tributylphosphine, triphenylphosphine, tris (pentafluorophenyl) phosphine, alkyls such as trimethylphosphine oxide, triethylphosphine oxide In addition to phosphine oxide, commercially available products include “ADK STAB (registered trademark) 2112”, “ADK STAB (registered trademark) PEP-8”, “ADK STAB (registered trademark) 260”, “ADK STAB (registered trademark) 3010”, “ADK STAB” (Registered trademark) HP-10 ”,“ ADEKA STAB (registered trademark) 329K ”,“ ADEKA STAB (registered trademark) PEP-24G ”(manufactured by Asahi Denka Co., Ltd.),“ HCA ”(manufactured by Sanko Co., Ltd.),“ IRGAFOS 168 ”( Phosphorous compounds such as Ciba); nonylphenol, mono-t-butyl-p-cresol, mono-t-butyl-m-cresol, 2,4-dimethyl-6-t-butyl-phenol, 2,6-di- t-butyl-p-cresol, 2,6-di-t-butylphenol, 4-hydroxymethyl-2,6-di-t-butyl-phenol, methoquinone, guaiacol, 3-methoxyphenol, 4-methoxyphenol, hydroquinone , Methylhydroquinone, t-butylhydroquinone, catechol, 4-methylcatechol, 4-t-butylcatechol, resor In addition to sinol, 2-methylresorcinol, 5-methylresorcinol, and propyl gallate, commercially available products include “Sumilyzer (registered trademark) GM”, “Sumilyzer (registered trademark) GS” (manufactured by Sumitomo Chemical Co., Ltd.), “IRGANOX1222” ( Phenol compounds such as Ciba); commercially available products such as “Sumilyzer (registered trademark) TPL-R”, “Sumilyzer (registered trademark) TPS”, “Sumilyzer (registered trademark) TPD” (manufactured by Sumitomo Chemical Co., Ltd.) Organic sulfur compounds such as “IRGANOXHP2225FF”, “IRGANOXHP2341”, “IRGANOXHP2921FF” (above, manufactured by Ciba), etc .; metals such as zinc dibutyldithiocarbamate and copper dibutyldithiocarbamate Complexes; Feni -Α-naphthylamine, N, N′-diphenyl-p-phenylenediamine, 4,4-tetramethyldiaminodiphenylamine, piperidine, 2,6-dimethylpiperidine, 2,2,6,6-tetramethylpiperidine, piperidino In addition to oxyfree radicals, 2,6-dimethylpiperidino free radicals, 2,2,6,6-tetramethylpiperidino free radicals, commercially available products such as “CXA5415” and “ZJ705” (above, manufactured by Ciba) Examples of commercially available products include nitroso compounds such as “Q1300” and “Q1301” (above, manufactured by WAKO); and phenothiazine. These polymerization inhibitors may be used alone or in combination of two or more.

  Although the addition amount of the polymerization inhibitor is not particularly limited, it is usually preferable that the ratio to the produced RHMAs is within a range of 0.0001 to 5% by mass.

  As the molecular oxygen, for example, an oxygen-nitrogen mixed gas or air can be used. In this case, an oxygen-containing gas may be blown into the reaction system (so-called bubbling).

  The reaction temperature at the time of synthesizing the RHMA is not particularly limited as long as the reaction proceeds, but it is preferably performed at 40 to 160 ° C. in order to suppress polymerization of the raw material or product. More preferably, it is 60-100 degreeC. If the reaction temperature is too low, the reaction rate tends to be low and the reaction tends to take a long time, which is not preferable.

  The reaction solution obtained as described above contains a catalyst, unreacted raw materials (α, β-unsaturated carboxylic acid esters, aldehydes), a solvent and the like together with the target RHMA. It is preferable to remove them by appropriately using known methods such as filtration, recrystallization, crystallization, distillation, extraction / washing with water or an organic solvent. In addition, since the obtained reaction liquid often contains the above-mentioned specific high-boiling impurities and other impurities (low-boiling impurities, etc.), distillation, crystallization, extraction with an organic solvent, etc. to remove them. It is preferable to purify The removal of the specific high boiling point impurities is as described above.

2. RHMA-derived polymer The RHMA-derived polymer in the present invention is a polymer containing an α-hydroxyalkyl acrylate unit (hereinafter sometimes referred to as “uncyclized polymer”) or a polymer containing an α-hydroxyalkyl acrylate unit. A polymer in which a ring structure is introduced into the main chain (hereinafter also referred to as a “ring structure-containing polymer”), both of which can be obtained by polymerization using the above-described RHMA as a raw material monomer. it can.

2.1. Uncyclized polymer The uncyclized polymer may be a homopolymer having only the above-described RHMA unit of the present invention, or another monomer capable of copolymerizing with the RHMA unit together with the above-described RHMA unit of the present invention. It may also be a copolymer having body-derived units.

  The other monomer is not particularly limited as long as it is copolymerizable with RHMA, but a vinyl monomer having a polymerizable double bond is preferable. In particular, when a ring structure-containing polymer described later is used, as other monomers, for example, a polymerizable monomer having a carboxyl group, a polymerizable monomer having an ester group, and a polymerizable monomer having a hydroxyl group are used. It is preferable to select a polymerizable monomer having a ring-forming functional group such as a monomer (however, a monomer other than RHMA), a polymerizable monomer having an amino group or an amide group. Among these, a polymerizable monomer having a carboxyl group, a polymerizable monomer having an ester group, and a polymerizable monomer having a hydroxyl group are particularly preferable. In addition, only 1 type may be sufficient as another monomer, and 2 or more types may be sufficient as it.

  Examples of the polymerizable monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, α-substituted acrylic acid, α-substituted methacrylic acid, maleic acid, and succinic acid. Among these, Acrylic acid and methacrylic acid are preferred.

  Examples of the polymerizable monomer having an ester group include acrylic acid such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, and benzyl acrylate. Esters include: methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, and the like. In view of excellent heat resistance and transparency of the polymer from which methyl methacrylate is obtained.

  Examples of the polymerizable monomer having a hydroxyl group (monomer other than RHMA) include α-hydroxyalkylstyrene such as α-hydroxymethylstyrene and α-hydroxyethylstyrene; 2-hydroxyethyl (meth) acrylate, Hydroxyalkyl esters of (meth) acrylic acid such as 2-hydroxypropyl (meth) acrylate; 2- (hydroxyalkyl) acrylic acid such as 2- (hydroxymethyl) acrylic acid and 2- (hydroxyethyl) acrylic acid; Can be mentioned.

  In addition to the above, it is also preferable to select an ultraviolet-absorbing polymerizable monomer as the other monomer from the viewpoint of imparting weather resistance. Examples of the UV-absorbing polymerizable monomer include known ones such as a benzotriazole-based UV-absorbing monomer and a triazine-based UV-absorbing monomer.

  When the uncyclized polymer also has units derived from other monomers, the content of α-hydroxyalkyl acrylate units is preferably 1% by mass or more and 40% by mass or less, more preferably It is 3 mass% or more and 30 mass% or less, More preferably, it is 5 mass% or more and 20 mass% or less.

The uncyclized polymer can be obtained by appropriately polymerizing the monomer component containing the RHMA and, if necessary, the other monomer according to a known polymerization method.
In the polymerization reaction for obtaining an uncyclized polymer, a solvent can be used as necessary. The solvent is not particularly limited, and examples thereof include aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ether solvents such as tetrahydrofuran; Or 2 or more types are mentioned.

  In the polymerization reaction for obtaining an uncyclized polymer, a known polymerization initiator can be used as necessary. The polymerization initiator is not particularly limited, and examples thereof include cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, and t-butyl peroxyisopropyl carbonate. , Organic peroxides such as t-amylperoxy-2-ethylhexanoate and tertiary amylperoxyisononanoate; 2,2′-azobis (isobutyronitrile), 1,1′-azobis (cyclohexane Carbonitrile), azo compounds such as 2,2′-azobis (2,4-dimethylvaleronitrile); The amount of the polymerization initiator used may be appropriately set according to the combination of polymerizable monomers and reaction conditions.

  The polymerization conditions in the polymerization reaction for obtaining the uncyclized polymer are not particularly limited and may be appropriately set according to the type and ratio of the polymerizable monomer to be used. The polymerization time is preferably 0 ° C. to 150 ° C. and a polymerization time of 0.5 hour to 20 hours, more preferably a polymerization temperature of 80 ° C. to 140 ° C. and a polymerization time of 1 hour to 10 hours. It's time. In the present invention, since the content of high-boiling impurities in RHMA is reduced to a predetermined amount or less, it is possible to suppress the adhesion of the gel material to the polymerization kettle even if the polymerization reaction is continuously performed.

  The molecular weight of the uncyclized polymer is not particularly limited. For example, the weight average molecular weight is preferably 1,000 or more and 2,000,000 or less, more preferably 5,000 or more and 1,000,000 or less, Preferably they are 50,000 or more and 500,000 or less.

2.2. Ring structure-containing polymer The ring structure-containing polymer is obtained by introducing a ring structure into the main chain of the uncyclized polymer. Examples of the ring structure of the main chain include a lactone structure, a glutaric anhydride structure, and an imide structure (glutarimide structure, maleimide structure, etc.). Among these, a lactone structure is preferable in terms of high heat resistance, excellent transparency, and mechanical strength.

  The ring structure-containing polymer may be prepared by, for example, introducing a unit derived from a polymerizable monomer having a ring-forming functional group into the uncyclized polymer, and allowing the cyclization condensation reaction to proceed after the polymerization reaction. Can be obtained. For example, if a lactone ring structure is to be introduced, the uncyclized polymer has a hydroxyl group and an ester group, and the alcohol is heated in the presence of a catalyst as necessary to remove the alcohol. It can be formed by advancing the accompanying lactone cyclization condensation reaction.

  The cyclization condensation reaction for obtaining the ring structure-containing polymer and the polymerization method of the uncyclized polymer for enabling the cyclization condensation reaction are not particularly limited except that RHMA in the present invention is essential. For example, when a lactone ring structure is introduced, the methods described in JP-A-2006-96960, JP-A-2006-171464, JP-A-2007-63541 and the like are appropriately employed. In the case of introducing a glutaric anhydride structure or an imide structure, Japanese Patent Application Laid-Open No. 2007-31537, International Publication No. 2007/26659, International Publication No. 2005/108438, Japanese Patent Application Laid-Open No. 57-153008. What is necessary is just to employ | adopt the method as described in the gazette etc. suitably.

  The molecular weight of the ring structure-containing polymer is not particularly limited. For example, the weight average molecular weight is preferably 1,000 or more and 2,000,000 or less, more preferably 5,000 or more and 1,000,000 or less, Preferably they are 50,000 or more and 500,000 or less.

3. Thermoplastic Resin Composition The thermoplastic resin composition of the present invention is a polymer containing an α-hydroxyalkyl acrylate unit or a polymer having a cyclic structure introduced into the main chain of the polymer (the RHMA-derived polymer described above). It is a thermoplastic resin composition containing at least one. A resin composition containing a polymer containing an α-hydroxyalkyl acrylate unit can exhibit excellent weather resistance. In addition, it is known that a resin composition containing a polymer having a cyclic structure introduced into the main chain of the polymer exhibits excellent heat characteristics such as high heat resistance, high transparency and low birefringence. It has been. In particular, methacrylic resins are excellent in surface gloss and light resistance, and are excellent in the balance of mechanical strength, molding processability and surface hardness.

  In the thermoplastic resin composition of the present invention, the content of the RHMA-derived polymer is, for example, preferably 50% by mass or more, more preferably 55% by mass or more, in 100% by mass of the thermoplastic resin composition. More preferably, it is 60 mass% or more. Moreover, there is no restriction | limiting in particular in upper limit, 100 mass% may be sufficient, Preferably it is 98 mass% or less, More preferably, it is 95 mass% or less.

  The thermoplastic resin composition of the present invention is, as necessary, for example, polyethylene, polypropylene, ethylene-propylene copolymer, poly (4) in addition to the RHMA-derived polymer as long as the effects of the present invention are not impaired. Olefin polymers such as methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins; polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block co Styrene polymers such as polymers; Polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; Polyamides such as nylon 6, nylon 66 and nylon 610; Cellulose triacetate and cellulose acetate propylene Cellulose esters such as acrylate and cellulose acetate butyrate; Polyacetal: Polycarbonate; Polyphenylene oxide; Polyphenylene sulfide: Polyether ether ketone; Polysulfone; Polyethersulfone; Polyoxypentylene; Polyamideimide; It may contain other thermoplastic resins such as rubber polymers such as ABS resin and ASA resin. In addition, for example, hindered phenol-based, phosphorus-based, sulfur-based and the like antioxidants; light-resistant stabilizers, weather-resistant stabilizers, heat-stabilizers and other stabilizers; glass fibers, carbon fibers and other reinforcing materials; ultraviolet absorbers; Near-infrared absorbers; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide; antistatic agents such as anionic, cationic and nonionic surfactants; inorganic pigments, organic pigments, dyes, etc. Various additives such as colorants; organic fillers and inorganic fillers; resin modifiers; organic fillers and inorganic fillers; plasticizers; These contents are preferably adjusted so that the content of the RHMA-derived polymer is in the above-described range.

  In the thermoplastic resin composition of the present invention, the number of foreign matters (fine foreign matters) having a major axis of 5 μm or more and less than 20 μm is 100 / g or less. As described above, the thermoplastic resin composition in which the number of fine foreign substances is in a specific range can be obtained by setting the content of the specific high-boiling impurities contained in RHMA to a predetermined amount or less. The number of foreign matters having a major axis of 5 μm or more and less than 20 μm is preferably 80 pieces / g or less, more preferably 60 pieces / g or less, and further preferably 30 pieces / g or less. The term “foreign matter” as used in the present invention refers to a by-product such as a gel generated during polymerization in the production process until a resin composition is obtained, and a by-product such as a carbide generated due to deterioration of the polymer during a cyclization reaction. In addition to living things, it also includes contaminants mixed in each manufacturing process, and means all substances having properties that are not compatible with resin compositions. The number of the fine foreign matters can be measured, for example, by a method described later in Examples.

  The thermoplastic resin composition of the present invention is preferably filtered and purified using a known polymer filter (for example, the filtration accuracy is 10 μm or less) for the purpose of removing relatively large foreign matters having a major axis of 20 μm or more. Such filtration purification may be performed in consideration of, for example, the contents described in Patent Document 1 described above. In the thermoplastic resin composition of the present invention, fine foreign matters are reduced to a predetermined amount or less, so that clogging of the polymer filter can be reduced.

  In the thermoplastic resin composition of the present invention, since fine foreign substances are reduced to a predetermined amount or less, when it is used as a film or a molded body, it has few defects and high transparency. Because of these characteristics, the thermoplastic resin composition of the present invention can be used as a transparent material in various industrial parts such as automobile parts and home appliances, and an optical material in optical-related applications. It is preferable that it is used for a material. Examples of the optical material include members such as a polarizer protective film.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.
Analysis and evaluation in Examples and Comparative Examples were performed by the following methods.

<Gas chromatography analysis>
Gas chromatographic analysis of RHMA (methyl α-hydroxymethyl acrylate) was performed using a capillary column with a chemically bonded polyethylene glycol having a molecular weight of 20,000 (“SUPELCOWAX (registered trademark) 10” manufactured by Sigma-Aldrich) as a filler. The following analysis conditions were used. Specifically, 2 g of purified α-hydroxymethyl acrylate for analysis and 1.2 g of 2-methoxyethanol as an internal standard substance were weighed and mixed in a screw tube, and 1 μL was injected into the apparatus. In calculating each peak area, an area surrounded by each peak and an approximate baseline obtained by connecting the start point and end point of each peak with a straight line was calculated.

Equipment: “GC2014” manufactured by Shimadzu Corporation
Detector: Hydrogen flame detector Column: Capillary inner diameter 0.25 mm, length 10 m
Column temperature: After holding at 40 ° C. for 3 minutes, the temperature is raised to 230 ° C. at a temperature rising rate of 15 ° C./min, and held at 230 ° C. for 10 minutes. Detector temperature: 220 ° C.
Injection temperature: 220 ° C
Carrier gas: Helium carrier gas Flow rate: 3 mL / min Hydrogen amount: 0.7 kg / cm ²
Split: 85 mL / min Air amount: 0.7 kg / cm ²

  The high boiling point impurity content, the following ether dimer content, and the purity of purified α-hydroxymethyl acrylate (MHMA content) were determined by an internal standard method based on a calibration curve for MHMA.

  The calibration curve of MHMA uses methyl acrylate as a solvent, MHMA and 2-methoxyethanol as an internal standard substance, the concentration of the internal standard substance is constant, the concentration of MHMA is 0.05 mass%, 0 Samples to be .25% by mass, 0.50% by mass, 0.75% by mass, and 0.10% by mass were prepared and subjected to the gas chromatography analysis.

<Measurement of the number of fine foreign objects>
A measurement sample in which 5 g of the obtained resin composition was dissolved in 100 mL of chloroform was analyzed using a particle counter (manufactured by Pamas, model: SVSS-C, sensor specification: HCB-LD-50 / 50). The number of foreign matters (fine foreign matters) of 5 μm or more and less than 20 μm was measured and converted to the number per 1 g.

(Production example (production of crude methyl α-hydroxymethyl acrylate))
[Reaction process]
In a reactor, 17300 parts by mass of methyl acrylate as an acrylate ester, 1700 parts by mass of 92% by mass paraformaldehyde as a formaldehyde raw material, 1000 parts by mass of a 30% by mass trimethylamine aqueous solution as a tertiary amine compound, a polymerization inhibitor After adding 27 parts by mass of p-methoxyphenol and 17 parts by mass of copper dibutyldithiocarbamate as a stabilizer, the mixture was reacted at 70 ° C. for 8 hours to obtain 20400 parts by mass of a reaction solution.

[Washing process]
After the reaction, the obtained reaction solution was allowed to stand to separate into an organic phase and an aqueous phase, and an aqueous phase (800 parts by mass) was extracted. Next, 2400 parts by mass of water was added to the organic phase and washed with water to obtain 19600 parts by mass of the organic phase after washing with water.

[Acrylic ester removal process]
Next, methyl acrylate was distilled off from the organic phase after washing with water by distillation, so that the methyl acrylate content was 1% by mass or less. Specifically, the organic phase after washing with water is put into a container and heated under reduced pressure, and the pressure is gradually reduced and heated until the pressure reaches 67 hPa and the liquid temperature reaches 100 ° C., and 4700 parts by mass of the acrylate removal liquid is added. I got it.

[Low boiling point removal process]
Next, the obtained acrylate removal liquid is charged into a distillation apparatus equipped with a storage tank, and reaction by-products (low-boiling components) having a lower boiling point than that of methyl α-hydroxymethyl acrylate, which is the target product, are removed by distillation. 3100 parts by mass of crude methyl α-hydroxymethyl acrylate (MHMA) was obtained. The distillation conditions were 10 until the reflux ratio was 10, the pressure in the distillation equipment was 13 hPa, and the temperature at the top of the distillation column reached 85 ° C.

Example 1
The crude α-hydroxymethyl acrylate (MHMA) obtained in the production example was charged into a distillation apparatus used in the low boiling point component removing step, and distilled under the following conditions to obtain high purity purified α-hydroxymethyl acrylic acid. 1900 mass parts of methyl (A-1) was acquired. The distillation conditions were carried out until the reflux ratio was 0.4, the pressure in the distillation column was 13 hPa, and the temperature at the bottom of the distillation column reached 120 ° C.
The obtained purified methyl α-hydroxymethyl acrylate (A-1) was subjected to gas chromatographic analysis. As a result, the high boiling point impurity content (C _hbp ) of the purified methyl methyl α-hydroxymethyl acrylate (A-1) was The purity of the purified methyl α-hydroxymethyl acrylate (A-1) was 99.66% by mass, and the content of the ether dimer was 0.00% by mass.

  Next, in a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introduction pipe, 40 parts by mass of methyl methacrylate and purified methyl methyl α-hydroxymethyl acrylate (A-1) 10 obtained by the above distillation. 50 parts by mass of toluene was charged as a part by mass and a polymerization solvent. Next, the temperature was raised to 105 ° C. while introducing nitrogen gas into the reaction vessel, and when refluxing accompanying the temperature rise began, tertiary amyl peroxyisononanoate (“Lupelox (registered trademark) manufactured by Arkema Yoshitomi Co., Ltd.) was used as a polymerization initiator. 570 ") 0.03 parts by weight were added. At the same time, dropping of 0.06 part by mass of the above-mentioned tertiary amyl peroxyisononanoate was started, and solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C. while dropping over 2 hours. After completion of the dropwise addition, the reaction vessel was kept warm and maintained at the same temperature for aging for 4 hours.

Next, 0.05 parts by mass of stearyl phosphate (“Phoslex A-18” manufactured by Sakai Chemical Industry Co., Ltd.) as a catalyst for the cyclization reaction is added to the obtained polymerization solution, and refluxed at about 90 ° C. to 110 ° C. The cyclization condensation reaction to form a lactone ring structure was allowed to proceed for 2 hours. Subsequently, the obtained polymerization solution was passed through a multitubular heat exchanger heated to 240 ° C. to complete the cyclization condensation reaction. Subsequently, the reaction solution after the cyclization condensation reaction was subjected to a barrel temperature of 250 ° C., a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1 and a forevent number of 4 (first and second from the upstream side). , Referred to as third and fourth vents), a leaf disk type polymer filter (filtration accuracy 5 μm) is connected to the tip portion via a gear pump, and a side feeder is provided between the third vent and the fourth vent. Introduced into a type screw twin screw extruder (L / D = 52) at a processing rate of 24.0 parts by mass / hour (resin amount conversion), devolatilizing and simultaneously polymer filtering, and lactone ring structure A thermoplastic resin composition (B-1) comprising a methacrylic polymer having a main chain was obtained. At this time, a styrene-acrylonitrile copolymer (the copolymerization ratio of styrene / acrylonitrile was 73% by mass / 27% by mass and the weight average molecular weight was 220,000) was charged from the side feeder at a charging rate of 3 parts by mass / hour. In the above treatment, 0.0083 parts by mass of zinc octylate (“Nikka Octix Zinc 18%” manufactured by Nippon Kagaku Sangyo Co., Ltd.) is used as a foaming inhibitor (deactivator) before the third vent. 0.0025 parts by mass of an antioxidant (“Irganox (registered trademark) 1010” manufactured by BASF Japan) and 0.0025 parts by mass of a sulfur-based antioxidant (“ADEKA STAB (registered trademark) AO-412S” manufactured by ADEKA) Was dissolved in 0.075 parts by mass of toluene at a treatment rate of 0.106 parts by mass / hour.
The number of fine foreign substances contained in the obtained thermoplastic resin composition (B-1) was 24 / g.

(Example 2)
The distillation of the crude α-hydroxymethyl acrylate in Example 1 was carried out in the same manner as in Example 1 except that the distillation was carried out until the temperature at the bottom of the distillation column reached 125 ° C. -2000 mass parts of methyl hydroxymethyl acrylate (A-2) was acquired.
The obtained purified methyl methyl α-hydroxymethyl acrylate (A-2) was analyzed by gas chromatography. The high boiling point impurity content (C _hbp ) of the purified methyl methyl α-hydroxymethyl acrylate (A-2) was The purity of the purified methyl α-hydroxymethyl acrylate (A-2) was 99.53% by mass, and the ether dimer content was 0.00% by mass.

Next, in Example 1, in place of the purified α-hydroxymethyl acrylate (A-1), the purified α-hydroxymethyl acrylate (A-2) obtained by the above distillation was used. Performed the same operation as Example 1, and obtained the thermoplastic resin composition (B-2) which consists of a methacryl polymer which has a lactone ring structure in a principal chain.
The number of fine foreign substances contained in the obtained thermoplastic resin composition (B-2) was 52 / g.

(Comparative Example 1)
In the distillation of the crude methyl α-hydroxymethyl acrylate in Example 1, it was carried out in the same manner as in Example 1 except that the temperature at the bottom of the distillation column reached 150 ° C. -2000 mass parts of methyl hydroxymethyl acrylate (A-3) were acquired.
The obtained purified methyl methyl α-hydroxymethyl acrylate (A-3) was subjected to gas chromatographic analysis. As a result, the high boiling point impurity content (C _hbp ) of the purified methyl methyl α-hydroxymethyl acrylate (A-3) was The purity of the purified methyl α-hydroxymethyl acrylate (A-3) was 99.03% by mass, and the content of the ether dimer was 0.00% by mass.

Next, in Example 1, in place of the purified α-hydroxymethyl acrylate (A-1), the purified α-hydroxymethyl acrylate (A-3) obtained by the above distillation was used. Performed the same operation as Example 1, and obtained the thermoplastic resin composition (B-3) which consists of a methacryl polymer which has a lactone ring structure in a principal chain.
The number of fine foreign substances contained in the obtained thermoplastic resin composition (B-3) was 156 / g.

(Comparative Example 2)
The crude methyl α-hydroxymethyl acrylate (MHMA) obtained in the production example was charged into a thin film distiller, and distilled under the following conditions to obtain highly purified purified methyl methyl α-hydroxymethyl acrylate (A-4). 1900 parts by mass were obtained. Distillation conditions were carried out by setting the distillation column pressure to 13 hPa, the jacket temperature to 120 ° C., and the distillate to feed ratio to 60%.
The obtained purified methyl methyl α-hydroxymethyl acrylate (A-4) was subjected to gas chromatography analysis. As a result, the high boiling point impurity content (C _hbp ) of the purified methyl methyl α-hydroxymethyl acrylate (A-4) was The purity of purified methyl methyl α-hydroxymethylacrylate (A-2) was 99.01% by mass, and the content of ether dimer was 0.40% by mass.

Next, in Example 1, instead of the purified methyl α-hydroxymethyl acrylate (A-1), the purified α-hydroxymethyl acrylate (A-4) obtained by the above distillation was used. Performed the same operation as Example 1, and obtained the thermoplastic resin composition (B-4) which consists of a methacryl polymer which has a lactone ring structure in a principal chain.
The number of fine foreign substances contained in the obtained thermoplastic resin composition (B-4) was 180 / g.

Claims (4)

By distillation using a distillation column, a purified α-hydroxyalkyl acrylate having a high boiling point impurity content (C _hbp ) determined by the following formula of 0.6% by mass or less is obtained,
Using the obtained purified α-hydroxyalkyl acrylate as a raw material, a polymer containing an α-hydroxyalkyl acrylate unit and having at least one selected from the group consisting of a lactone structure, a glutaric anhydride structure, and an imide structure in the main chain Manufacturing method.
_{C hbp = (A hbp / A} std) × F RHMA × (W std / W total) × 100
_{(Wherein, A hbp, A std, F} RHMA, W std, W total Both, by gas chromatography using a capillary column which molecular weight is 20,000, bonded-polyethylene glycol fillers, purified α- hydroxy This is a value obtained by analyzing a sample containing an alkyl acrylate and an internal standard substance, of which A _std represents the peak area of the internal standard substance, and A _hbp represents the retention time of the purified α-hydroxyalkyl acrylate as 1. Among the peaks having a relative retention time of 0.90 to 1.30, the total area of the peaks excluding purified α-hydroxyalkyl acrylate is shown, provided that the relative retention time is 0.90 to 1.30. if it contains peaks ranging in polymerization inhibitor, the a _hbp, .F _RHMA free peak area of the polymerization inhibitor, purified α- hydrate It is the slope of the calibration curve showing the relationship between the mass ratio of the roxyalkyl acrylate and the internal standard substance and the peak area ratio, W _std indicates the mass of the internal standard substance in the implanted sample, and W _total is the implanted sample. The apparent mass of the purified α-hydroxyalkyl acrylate is shown.) The method for producing a polymer according to claim 1 , wherein the purified α-hydroxyalkyl acrylate is polymerized to cause lactone cyclization. The distillation is distilled to remove the low-boiling component distillation column top temperature is 85 ° C. or less at a pressure 13 hPa, to claim 1 or 2 comprised of a distillation again performed after removal of low boiling point components The manufacturing method of the polymer of description. The method for producing a polymer according to any one of claims 1 to 3 , wherein a foreign matter having a major axis of 20 µm or more is removed by a polymer filter.