JP2015172023A - Method for purifying (meth)acrylate, and method for producing (meth)acrylate polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for purifying (meth)acrylate, in which various coloration causing substances for causing coloration of a molded article can be removed at a low cost by using an inexpensive and simple facility, and to provide a method for producing a (meth)acrylate polymer having excellent transparency by polymerizing a monomer containing the purified (meth)acrylate.SOLUTION: The method for purifying (meth)acrylate, in which the (meth)acrylate is brought into contact with a cation exchange resin which satisfies such a requirement that when the cation exchange resin is washed with alcohol of the quantity equivalent to one time of the empty tower volume of the cation exchange resin, the alcohol used for washing the cation exchange resin has 1 or larger absorbance (β). The method for producing the (meth)acrylate polymer by polymerizing the monomer containing the purified (meth)acrylate is also provided.

Description

  The present invention relates to a method for purifying (meth) acrylic acid esters and a method for producing (meth) acrylic acid ester polymers.

  Methacrylic resin with methacrylic acid ester unit as the main component is excellent in weather resistance, transparency, surface gloss, mechanical strength, moldability, etc., optical material, signboard, lighting cover, machinery window, aquarium water tank, It is used for various applications such as various display device members.

  A typical example of the methacrylic acid ester used as a raw material for the methacrylic resin is methyl methacrylate.

  Examples of the industrial production method of methyl methacrylate include ACH method with ammonium sulfate by-product, improved ACH method without ammonium sulfate by-product, C4 oxidation method, method of obtaining ester directly from methacrolein and methanol, and methylacetylene The carbonylation method is known.

  Various (meth) acrylic acid esters can be produced, for example, by an ester exchange reaction between an alkyl (meth) acrylate and an alcohol or an esterification reaction between (meth) acrylic acid and an alcohol.

  The (meth) acrylic acid ester obtained by such a method contains a color-causing substance generated in the process of synthesizing the (meth) acrylic acid ester. Moreover, it is one of the manufacturing methods of a (meth) acrylic acid ester polymer, and has the process of collect | recovering and reusing unreacted (meth) acrylic acid ester, the single quantity containing (meth) acrylic acid ester In a continuous polymerization process using a body material, the color-causing substance and the color-causing substance generated in the polymerization step may be concentrated and recovered together with the unreacted (meth) acrylic acid ester.

  Molded products obtained using a (meth) acrylic acid ester polymer obtained by using a (meth) acrylic acid ester containing a large amount of the above various color-causing substances have a problem of coloring due to various color-causing substances. It may become.

  Examples of methods for removing the color causative substance include a method of removing the color causative substance by contacting with an ion exchange resin, a method of recovering only (meth) acrylate by distillation, and adsorbing the color causative substance with an adsorbent. The method of removing is mentioned. Among them, the method of removing the color-causing substance by bringing it into contact with an ion exchange resin is often used because it is easy to operate and produces little waste.

  As a method for removing a color-causing substance by contacting with an ion exchange resin, for example, Patent Document 1 discloses an amine compound or hydrazines after contacting a recovered unreacted monomer with a sulfonic acid group-containing cation exchange resin. And a method in which the recovered unreacted monomer is brought into contact with a sulfonic acid group-containing cation exchange resin, treated with an amine compound or hydrazine, and further distilled.

Japanese Patent Laid-Open No. 06-228,203

  It is possible to remove the aforementioned color-causing substances by the method of treating the recovered unreacted monomer with a sulfonic acid group-containing cation exchange resin and then treating with an amine compound or hydrazine in Patent Document 1. However, the color causative substance present in the cation exchange resin is not removed, and the coloring of the molded product due to the color causative substance present in the cation exchange resin may become a problem. The above problem can be solved by carrying out distillation after contact with the cation exchange resin, but the distillation equipment is expensive and difficult to say.

  The object of the present invention is to purify a (meth) acrylic ester and a purified (meth) capable of removing various coloring-causing substances resulting from coloring of a molded product at low cost using an inexpensive and simple equipment. It is providing the manufacturing method of the (meth) acrylic acid ester polymer excellent in transparency which superposes | polymerizes the monomer containing an acrylic acid ester.

The above problems are solved by the following inventions [1] to [15].
Invention [1] A method for purifying a (meth) acrylic acid ester by contacting a (meth) acrylic acid ester with a cation exchange resin, wherein the cation exchange resin is 1 volume relative to the empty space of the cation exchange resin. A method for purifying a (meth) acrylic acid ester, wherein the absorbance (β) of the alcohol after washing the cation exchange resin with a double amount of alcohol satisfies the requirement of 1 or less.
Invention [2] The cation exchange resin is washed with the absorbance (β) of the alcohol and the cation exchange resin after washing the cation exchange resin with 1 volume of alcohol with respect to the empty volume of the cation exchange resin. The method for purifying a (meth) acrylic acid ester according to [1], wherein the absorbance (α) of the alcohol before the treatment satisfies the requirement of the following formula (1).

0 ≦ [absorbance (β)] − [absorbance (α)] ≦ 0.1 (1)
Invention [3] Purification of (meth) acrylic acid ester according to [1] or [2], wherein the cation exchange resin is washed by a method comprising step A, step B and step C shown below in order. Method.
(Step A): A washing step in which an alcohol having an absorbance of 2 or less is brought into contact with the cation exchange resin at least 1 volume by volume with respect to the empty volume of the cation exchange resin.
(Step B): A washing step in which an alcohol satisfying the following conditions B1 and B2 is brought into contact with the cation exchange resin at least 1 volume by volume with respect to the empty volume of the cation exchange resin.

    (Condition B1): The absorbance is equal to or less than the absorbance of a mixture of alcohols flowing out from the time when the volume of alcohol is brought into contact with the empty volume of the cation exchange resin in Step A to the end of Step A.

(Condition B2): The alcohol which wash | cleaned the cation exchange resin is contained.
(Step C): A washing step of washing the cation exchange resin with an alcohol having an absorbance of 0.5 or less until the absorbance of the alcohol after washing the cation exchange resin becomes 0.5 or less.
Invention [4] The method for purifying a (meth) acrylic acid ester according to any one of [1] to [3], wherein the alcohol is at least one selected from methanol, ethanol, 1-propanol and isopropanol.
Invention [5] The method for purifying a (meth) acrylic acid ester according to [3] or [4], wherein the alcohol used in (Step B) contains 1 to 100 vol% of alcohol obtained by washing the cation exchange resin.
Invention [6] The method for purifying a (meth) acrylic acid ester according to any one of [1] to [5], wherein the cation exchange resin is a strongly acidic cation exchange resin.
Invention [7] The method for purifying a (meth) acrylic acid ester according to any one of [1] to [6], wherein the degree of crosslinking of the cation exchange resin is 5 to 20%.
Invention [8] The (meth) acrylate ester is methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethylene glycol di (meth) acrylate, Diethylene glycol (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolethanetri (meth) acrylate, pentaerythritol tetra (meth) acrylate, allyl (meth) acrylate, (meth) ) The method for purifying a (meth) acrylic acid ester according to any one of [1] to [7], comprising at least one selected from 2-hydroxyethyl acrylate.
Invention [9] Any one of [1] to [8], wherein the amount of alcohol used for washing is 2.5 to 10 volume times the empty volume of the cation exchange resin in one washing. The purification method of (meth) acrylic acid ester as described in 2.
Invention [10] The method for purifying a (meth) acrylic acid ester according to any one of [1] to [9], wherein the washing time of the cation exchange resin with alcohol is 0.2 to 5 hours per step.
Invention [11] The method for purifying a (meth) acrylic acid ester according to any one of [1] to [10], wherein the temperature of the alcohol used in the washing is 5 to 60 ° C.
Invention [12] The temperature of (meth) acrylic acid ester when contacting (meth) acrylic acid ester and cation exchange resin is 10 to 60 ° C. according to any one of [1] to [11] ) A method for purifying acrylic ester.
Invention [13] According to any one of [1] to [11], the superficial velocity when the (meth) acrylic acid ester is brought into contact with the cation exchange resin is 0.2 to 10 [1 / hr]. Purification method of (meth) acrylic acid ester.
Invention [14] A (meth) acrylic acid ester polymer (hereinafter referred to as “this”) that polymerizes a monomer containing a (meth) acrylic acid ester purified by the purification method according to any one of [1] to [13]. Polymer ").
Invention [15] A method for producing a continuous (meth) acrylate polymer comprising the following steps (1) to (4), wherein the step (3) is any one of [1] to [13]: A continuous production method of this polymer, which is a purification method of (meth) acrylic acid ester.
Step (1): A step of polymerizing a part of a monomer containing a (meth) acrylic acid ester to obtain a monomer mixture containing a (meth) acrylic acid ester polymer.
Step (2): A step of removing a monomer containing (meth) acrylic acid ester from the monomer mixture obtained in (1) to obtain a (meth) acrylic acid ester polymer.
Step (3): recovering the monomer containing the (meth) acrylic acid ester removed in (2), purifying the recovered (meth) acrylic acid ester, and purifying the (meth) acrylic acid ester Obtaining a monomer containing.
Step (4): The monomer containing the purified (meth) acrylic acid ester obtained in (3) is added as at least part of the monomer containing the (meth) acrylic acid ester in step (1). Process.

  Since the purification method of (meth) acrylic acid ester of the present invention can remove various color-causing substances resulting from coloring of molded articles at low cost using inexpensive and simple equipment, purified (meth) acrylic This polymer obtained by polymerizing monomers containing acid esters is excellent in transparency, and has high transparency such as optical materials, signboards, lighting covers, windows of machinery, aquarium water tanks, various display devices, etc. Is suitable for applications that require

FIG. 1: shows the flowchart which shows one embodiment of the manufacturing process of the (meth) acrylic acid ester polymer obtained with a continuous manufacturing method. FIG. 2 shows a flowchart showing one embodiment of a process for producing a (meth) acrylic acid ester polymer obtained by a continuous production method.

<(Meth) acrylic acid ester>
As (meth) acrylic acid ester used for this invention, ester of (meth) acrylic acid and a C1-C18 alcohol is mentioned, for example.

  Specific examples of the ester of (meth) acrylic acid and an alcohol having 1 to 18 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2- (meth) acrylic acid 2- Ethylhexyl, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylol ethane tri (meth) acrylate, trimethylol ethane tri (meth) acrylate, pentaerythritol tetra (meth) Examples include acrylate, allyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate.

  As the (meth) acrylic acid ester, methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate are preferable from the viewpoint that the effects of the present invention are sufficiently exhibited, and (meth) acrylic acid Methyl and butyl (meth) acrylate are more preferred, and methyl (meth) acrylate is still more preferred.

  The (meth) acrylic acid ester can be used alone or in combination of two or more.

  The content of the methacrylic acid ester in the (meth) acrylic acid ester is preferably 50% by mass or more and 100% by mass or less, and more preferably 70% by mass or more and 100% by mass or less.

  In the present invention, “(meth) acrylic acid ester” or “(meth) acrylate” is selected from at least one selected from “acrylic acid ester” and “methacrylic acid ester”, or “acrylate” and “methacrylate”, respectively. Means at least one selected.

  In the present invention, (meth) acrylic acid esters include aromatic vinyl monomers such as styrene, vinyl styrene and α-methyl styrene according to the purpose; vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; acrylic Other vinyl monomers such as α, β-unsaturated carboxylic acid such as acid, methacrylic acid and maleic acid; and acid anhydrides such as diacrylic anhydride, methacrylic anhydride and maleic anhydride may be included. .

  The (meth) acrylic acid ester may contain a sulfur compound.

  As a sulfur compound, the additive for improving the heat-resistant decomposability | degradability of the chain transfer agent at the time of superposing | polymerizing (meth) acrylic acid ester and the below-mentioned polymer is mentioned, for example.

  Examples of the sulfur compound include primary mercaptans such as n-propyl mercaptan, n-butyl mercaptan, n-hexyl mercaptan, n-heptyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and isopropyl mercaptan. 2 molecules selected from secondary mercaptans such as isobutyl mercaptan, isooctyl mercaptan, isodecyl mercaptan, sec-dodecyl mercaptan, tertiary alkyl mercaptans such as tert-butyl mercaptan, tert-dodecyl mercaptan, and the above mercaptans And dialkyl disulfides. These can be used alone or in combination of two or more.

  Content of a sulfur compound is 0.01-1.0 mass part with respect to 100 mass parts of monomers which contain a (meth) acrylic acid ester normally. By setting the content of the sulfur compound to 1.0 part by mass or less, the molecular weight of the polymer tends to be increased by using (meth) acrylic acid ester. Moreover, it exists in the tendency which can suppress the increase in the molecular weight of this polymer and can improve the fluidity | liquidity of this polymer by content of a sulfur compound being 0.01 mass part or more.

<Cation exchange resin>
The cation exchange resin used in the present invention can be selected according to the purpose from various conditions such as resin type, exchange capacity, and degree of crosslinking.

  As the cation exchange resin, a strongly acidic cation exchange resin is preferable in that the color-causing substance can be efficiently removed.

  Examples of commercially available strong acid cation exchange resins include Diaion PK216 and Diaion PK228 manufactured by Mitsubishi Chemical Corporation, and Amberlist 15E and Amberlist XH-2071 manufactured by Dow Chemical. These can be used alone or in combination of two or more.

  The cation exchange resin can reduce the shrinkage of the cation exchange resin when the (meth) acrylic acid ester is brought into contact with it, and can efficiently remove the color-causing substances. Is preferred. By setting the degree of crosslinking of the cation exchange resin to 5% or more, shrinkage of the cation exchange resin can be suppressed, and the color-causing substance tends to be efficiently removed. By setting the degree of crosslinking of the cation exchange resin to 20% or less, the volume of the cation exchange resin used can be suppressed, and the treatment effect per cation exchange resin tends to be improved.

  The cation exchange resin used in the purification of (meth) acrylic acid ester is an alcohol after contacting the cation exchange resin with 1 volume volume of alcohol described later with respect to the empty volume of the cation exchange resin. The light absorbency (β) of 1 satisfies the requirement of 1 or less. By using a cation exchange resin that satisfies the above conditions for the purification of (meth) acrylic acid ester, the coloring of the polymer obtained by using the purified (meth) acrylic acid ester is suppressed. Can do.

  The cation exchange resin used in the purification of (meth) acrylic acid ester can suppress the coloring of the polymer obtained by using the purified (meth) acrylic acid ester. The absorbance (β) of the alcohol after contacting the cation exchange resin with an alcohol, which will be described later, in an amount of 1 volume by volume with respect to the column volume satisfies the requirement of 1 or less, and the alcohol before contacting with the cation exchange resin. It is preferable that the absorbance (α) and the absorbance (β) of the alcohol satisfy the requirements of the following formula (1).

0 ≦ [absorbance (β)] − [absorbance (α)] ≦ 0.1 (1)
In the present invention, the empty volume is the volume of the column occupied by the cation exchange resin in the column when the column is filled with the cation exchange resin. Density is not considered. The empty volume is a value determined by the following method.

  A predetermined amount (X) of the cation exchange resin is packed in advance in a column for packing the cation exchange resin used in the method for purifying the (meth) acrylic acid ester of the present invention or a column similar to this column. . Next, after tapping the column, the washing alcohol is passed through, and when the cation exchange resin packing volume is stabilized, the column volume (Y) occupied by the cation exchange resin in the column is cation exchanged. The value (Y / X) divided by the mass (X) of the resin is taken as the experimental value γ. Subsequently, the value obtained by multiplying the packed amount of the cation exchange resin packed in the column for the purification method of the (meth) acrylic acid ester of the present invention by the experimental value γ is defined as the empty volume.

<Alcohol>
The alcohol used in the present invention is for washing a cation exchange resin used for purification of (meth) acrylic acid ester.

  Examples of the alcohol include primary alcohols, secondary alcohols, and tertiary alcohols having 1 to 5 carbon atoms. As the alcohol, methanol, ethanol, 1-propanol, isopropanol, 1-butanol and isobutanol, which are compatible with water, are preferable because the cation exchange resin can be efficiently washed, and the solvent can be easily replaced. In some respects, methanol, ethanol, and isopropanol, which are highly compatible with both water and (meth) acrylic acid esters, are more preferred.

  Alcohol can be used alone or in combination of two or more.

<Cleaning method of cation exchange resin>
Examples of the method for washing the cation exchange resin used for the purification of the (meth) acrylic acid ester include a method of bringing an alcohol into contact with the cation exchange resin.

  Examples of the method for contacting the alcohol with the cation exchange resin include: (a) a method in which the cation exchange resin and the alcohol are brought into contact with the cation exchange resin and the alcohol after adding the cation exchange resin and the alcohol into the container; ) A method in which the column is filled with a cation exchange resin, and the alcohol in contact with the cation exchange resin is withdrawn from the other end while supplying the alcohol at a constant speed from the column end, and (c) a centrifuge or a rotary filtration separation. An example is a method in which after the machine is filled with a cation exchange resin, alcohol is continuously dropped onto the cation exchange resin from a supply port. Among these, the method (b) is preferable in that it can be continuously washed and is efficient.

  Examples of the washing method when washing by the above method (b) include, for example, a method for washing a column packed in a dedicated washing column and a cation used for purifying the (meth) acrylic acid ester of the present invention. A method of washing in a column filled with an exchange resin can be mentioned. When washing by the latter method, for example, a dedicated alcohol washing line can be provided in the cation exchange resin column.

  The amount of alcohol used for washing the cation exchange resin is such that the cation exchange resin after washing has an absorbance of 1 or less after the alcohol is brought into contact with the cation exchange resin. Although it will not specifically limit if it exists, 2.5-10 volume times amount is preferable with respect to the superficial volume of cation exchange resin, and 3-5 volume times amount is more preferable. By setting the amount of alcohol used for washing the cation exchange resin to 2.5 volume times or more, the cation exchange resin is sufficiently washed, and coloring of the polymer tends to be suppressed. Moreover, it exists in the tendency which can suppress washing | cleaning cost by making the quantity of the alcohol used for washing | cleaning of a cation exchange resin into 10 volume times or less.

  Although the time for washing the cation exchange resin with alcohol is not particularly limited, washing efficiency can be improved by bringing the cation exchange resin into contact with the alcohol for a long time. The contact time between the cation exchange resin and the alcohol is preferably from 0.2 to 5.0 hours, and more preferably from 0.5 to 2.0 hours, in terms of detergency and shortening of the washing time. When the cation exchange resin and alcohol are continuously contacted in the column, the superficial velocity (SV) (1 / time) is preferably 0.2 to 5.0, and SV is 0.5 to 2.5. Is more preferable.

  A new alcohol may be used for cleaning the cation exchange resin, but a recovered alcohol obtained by recovering the alcohol used for cleaning the cation exchange resin may also be used.

  As temperature of the alcohol used for washing | cleaning of a cation exchange resin, 5-60 degreeC is preferable. By setting the alcohol temperature to 5 ° C. or higher, the color-causing substance tends to be efficiently removed. Moreover, it exists in the tendency which can suppress the fall of the removal effect of the coloring cause substance by deterioration of cation exchange resin by making the temperature of alcohol 60 degrees C or less. Further, the temperature of the alcohol used for washing the cation exchange resin is more preferably 10 to 50 ° C. in that the deterioration of the cation exchange resin can be suppressed while maintaining the effect of removing the color-causing substance.

Examples of the method for washing the cation exchange resin with alcohol include a washing method in which the following steps A to C are sequentially performed, and the cation exchange resin can be efficiently washed. (Step A): A washing step in which an alcohol having an absorbance of 2 or less is brought into contact with the cation exchange resin in an amount of 1 to 2 times the volume of the empty space of the cation exchange resin.
(Step B): A washing step in which an alcohol satisfying the following conditions B1 and B2 is brought into contact with the cation exchange resin at least 1 volume by volume with respect to the volume of the cation exchange resin.

    (Condition B1): The absorbance is equal to or less than the absorbance of a mixture of alcohols flowing out from the time when the volume of the cation exchange resin is brought into contact with the volume of the cation exchange resin in step A to the end of step A.

(Condition B2): The alcohol which wash | cleaned the cation exchange resin is contained.
(Step C): A washing step of washing the cation exchange resin with an alcohol having an absorbance of 0.5 or less until the absorbance of the alcohol after washing the cation exchange resin becomes 0.5 or less.

<Process A>
As the alcohol used in the step A, a new alcohol may be used, or an alcohol brought into contact with a cation exchange resin may be reused.

  The absorbance of the alcohol used is preferably 2 or less, more preferably 1 or less, from the viewpoint of washing efficiency.

  Dispose of alcohol less than 1 volume by volume with respect to the empty volume of the cation exchange resin in contact with the cation exchange resin, or reuse it after purifying and reusing or diluting with new alcohol. May be. In view of cost, it is preferable to reuse the alcohol after contacting the cation exchange resin by 1 volume or more with respect to the empty volume of the cation exchange resin.

  As the amount of the alcohol to be brought into contact with the cation exchange resin, it is preferable to use 1 volume or more of alcohol, and 1.5 volume or more of alcohol relative to the empty volume of the cation exchange resin. Is more preferable. By using the (meth) acrylic acid ester purified by the cation exchange resin by setting the amount of alcohol to be brought into contact with the cation exchange resin to 1 volume or more by volume with respect to the empty volume of the cation exchange resin. Coloring of the resulting polymer can be suppressed. Further, the amount of alcohol to be brought into contact with the cation exchange resin is preferably 5 volume times or less, more preferably 3 volume times or less with respect to the empty volume of the cation exchange resin, from the viewpoint of cost.

<Process B>
Process B is a cleaning process subsequent to Process A, in which alcohol satisfying Condition B1 and Condition B2 is brought into contact with the cation exchange resin in an amount of 1 volume or more with respect to the empty volume of the cation exchange resin. It is.

  There is a tendency that the cation exchange resin can be sufficiently cleaned by bringing the cation exchange resin into contact with one or more times by volume of alcohol relative to the empty space of the cation exchange resin.

  The absorbance of the alcohol used is preferably not more than the absorbance of the mixture of alcohols flowing out from the time when the volume of the alcohol is brought into contact with the empty volume of the cation exchange resin in the process A to the end of the process A. The absorbance of the alcohol used is preferably 1.5 or less, more preferably 1.0 or less, from the viewpoint of washing efficiency of the cation exchange resin.

  Moreover, it is preferable that alcohol after contacting a cation exchange resin is contained in the alcohol to be used. The alcohol used in Step B may be used in the whole amount recovered after contacting with the cation exchange resin, but the recovered alcohol may be diluted with new alcohol.

  As the recovered alcohol, the alcohol recovered in step A can be used. When the washing is carried out in two or more times, those recovered in Step B or Step C can also be used.

  As for content of the collect | recovered alcohol in the alcohol to be used, 1-100 vol% is preferable. By setting the content of the recovered alcohol to 1 vol% or more, the cleaning cost tends to be suppressed. Moreover, it exists in the tendency which can make the washing | cleaning efficiency of a cation exchange resin favorable by content of the collect | recovered alcohol being 100 vol% or less. As a lower limit of content of the collect | recovered alcohol, 20 vol% or more is more preferable.

  The alcohol recovered after contacting with the cation exchange resin may be selected and recovered among the alcohols contacted with the cation exchange resin in step A and satisfying the condition B1, or the entire amount may be recovered. Later, it may be diluted with fresh alcohol. In addition, when washing is performed by dividing the number of times, the alcohol that has contacted the cation exchange resin in Step B or Step C may be stored and used in Step B.

<Process C>
In step C, the cation exchange resin washed in step B is brought into contact with an alcohol having an alcohol absorbance of 0.5 or less until the alcohol absorbance after being brought into contact with the cation exchange resin is 0.5 or less. It is a process. The alcohol absorbance after contacting with the cation exchange resin is less than 0.3 in terms of suppressing the coloring of the polymer obtained using the (meth) acrylic acid ester purified by the cation exchange resin. Preferably, 0.1 or less is more preferable.

  The amount of alcohol used for washing is an empty volume of the cation exchange resin in that the coloration of the polymer obtained using the (meth) acrylic acid ester purified by the cation exchange resin can be suppressed. 1 volume times or more is preferable. In addition, the amount of alcohol used for washing is preferably 2 volume times or less with respect to the empty volume of the cation exchange resin in terms of washing efficiency.

  The alcohol used may be fresh alcohol, or may be alcohol recovered after contact with the cation exchange resin. If the absorbance of the alcohol used in step B is 0.5 or less, step C may be performed subsequent to step B. In the case where the absorbance of the alcohol used in Step B exceeds 0.5, it is possible to use a solution diluted with new alcohol to have an absorbance of 0.5 or less. By using a new alcohol, it tends to be possible to suppress the coloring of the alcohol impregnated in the cation exchange resin, and it tends to be possible to obtain a (meth) acrylic acid ester having a smaller content of coloring components. .

<Purification method of (meth) acrylic acid ester>
Purification of (meth) acrylic acid ester is carried out by bringing (meth) acrylic acid ester into contact with a cation exchange resin.

  As the cation exchange resin, it is preferable to use a cation exchange resin that has been washed with a (meth) acrylate ester in that the content of impurities in the purified (meth) acrylate ester can be suppressed.

  Examples of the method of contacting the (meth) acrylic acid ester with the cation exchange resin include, for example, (a) adding the cation exchange resin and the (meth) acrylic acid ester into the container, and stirring the mixture for a certain period of time. A method of bringing the exchange resin into contact with the (meth) acrylate ester, (b) filling the column with a cation exchange resin, and supplying the (meth) acrylate ester from the column end at a constant rate, while the cation is supplied from the other end. (C) A method of extracting the (meth) acrylic acid ester in contact with the exchange resin and (c) after filling the centrifuge or rotary filter separator with the cation exchange resin, from the supply port of the centrifuge or rotary filter separator A method in which (meth) acrylic acid ester is supplied and continuously applied to the cation exchange resin can be mentioned. Among these, the method (b) is preferable in that (meth) acrylic acid ester can be purified continuously and is efficient.

  The conditions for bringing the (meth) acrylate ester into contact with the cation exchange resin include, for example, filling the column with a cation exchange resin and supplying the acrylate ester from the column end at a constant rate while the cation from the other end. In the method of extracting the acrylate ester in contact with the exchange resin, the SV of the (meth) acrylate ester when passing through the cation exchange resin packed in the column is preferably 0.2 to 10.0. By setting SV to 0.2 or more, the production of by-products of (meth) acrylic acid ester tends to be suppressed. Moreover, it exists in the tendency which can make the refinement | purification efficiency of (meth) acrylic acid ester favorable by making SV into 10.0 or less.

  The temperature at which the (meth) acrylate ester and the cation exchange resin are brought into contact with each other is not particularly limited as long as the performance of the cation exchange resin does not change, but is 10 in terms of the purification efficiency of the (meth) acrylate ester. -60 degreeC is preferable and 30-50 degreeC is more preferable.

<Method for producing (meth) acrylic acid ester polymer>
In the present invention, a (meth) acrylic acid ester polymer can be obtained by polymerizing a monomer containing a (meth) acrylic acid ester purified by the cation exchange resin.

  Examples of the polymerization method of the monomer containing the (meth) acrylic acid ester include a radical polymerization method.

  Examples of the radical polymerization method include a bulk polymerization method, a suspension polymerization method, a solution polymerization method, and an emulsion polymerization method. Among these, the bulk polymerization method is preferable in terms of productivity and polymerization stability. Of the bulk polymerization methods, the continuous bulk polymerization method is preferred.

  In radical polymerization of a monomer containing a (meth) acrylic acid ester, a monomer obtained by adding a radical polymerization initiator and, if necessary, a chain transfer agent, can be polymerized.

In the present invention, for example, a (meth) acrylic acid ester polymer can be continuously obtained by a continuous bulk polymerization method including the following steps (1) to (4).
Step (1): A step of polymerizing a part of a monomer containing a (meth) acrylic acid ester to obtain a monomer mixture containing a (meth) acrylic acid ester polymer.
Step (2): A step of removing a monomer containing (meth) acrylic acid ester from the monomer mixture obtained in (1) to obtain a (meth) acrylic acid ester polymer.
Step (3): The monomer containing the (meth) acrylic acid ester removed in (2) is recovered, the (meth) acrylic acid ester is purified, and the single monomer containing the purified (meth) acrylic acid ester is collected. A step of obtaining a polymer.
Step (4): The monomer containing the purified (meth) acrylic acid ester obtained in (3) is added as at least a part of the monomer containing the (meth) acrylic acid ester in Step (1). Process.

  In said process (4), at least 1 sort (s) chosen from a (meth) acrylic acid ester and a chain transfer agent is added to the monomer containing the (meth) acrylic acid ester obtained by refinement | purification, and a monomer By adjusting the composition, it can be subjected to polymerization again as a monomer containing a (meth) acrylic acid ester.

  Examples of the radical polymerization initiator include tert-butylperoxy-3,5,5-trimethylhexanate, tert-butylperoxylaurate, tert-butylperoxyisopropyl monocarbonate, and tert-hexylperoxyisopropyl. Monocarbonate, tert-butylperoxyacetate, 1,1-bis (tert-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, tert-butylperoxy 2-ethyl hexanate, tert-butyl peroxyisobutyrate, tert-hexyl peroxy 2-ethyl hexanate, di-tert-butyl peroxide, di-tert-hexyl peroxide, 2,5-dimethyl Organic peroxides such as -2,5-bis (tert-butylperoxy) hexane; and 2- (carbamoylazo) -isobutyronitrile, 1,1'-azobis (1-cyclohexanecarbonitrile), 2, 2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), dimethyl 2,2'-azobisisobutyrate, 2,2'-azobis (2,4,4- Examples thereof include azo compounds such as trimethylpentane) and 2,2′-azobis (2-methylpropane). These can be used alone or in combination of two or more.

  Although the usage-amount of a radical polymerization initiator can be arbitrarily adjusted according to superposition | polymerization temperature, average residence time, or the target polymerization rate, with respect to 100 mass parts of monomers containing (meth) acrylic acid ester. 0.001-1 mass part is preferable. When the amount of the radical polymerization initiator used is 0.001 part by mass or more, a target polymerization rate tends to be obtained. Moreover, it exists in the tendency which can reduce raw material cost by making the usage-amount of a radical polymerization initiator into 1 mass part or less.

  The preferred temperature range for the polymerization temperature varies depending on the polymerization method. For example, in the above step (1), the polymerization is carried out while continuously extracting the polymer composition polymerized to the desired polymerization rate in the complete mixing reactor. The polymerization temperature is preferably 110 to 170 ° C. By setting the polymerization temperature to 110 ° C. or higher, more preferably 120 ° C. or higher, there is a tendency that the acceleration phenomenon of the polymerization rate due to the gel effect is suppressed and stable production can be achieved. Moreover, it exists in the tendency which can make favorable physical properties, such as transparency of a (meth) acrylic acid ester polymer, mechanical strength, a heat-deformation temperature, and heat-resistant decomposition property, by making superposition | polymerization temperature into 170 degrees C or less.

  When it manufactures industrially stably by a continuous polymerization method, in the said process (1), it is preferable that the polymerization rate of the monomer containing (meth) acrylic acid ester shall be 35 to 65%. By setting the polymerization rate to 65% or less, mixing of monomers and heat transfer to the monomer tend to be good. Moreover, it exists in the tendency which can make productivity of a (meth) acrylic acid ester polymer favorable by making a polymerization rate into 35% or more.

  When continuous polymerization is carried out using a fully mixed reactor, the amount of the (meth) acrylate polymer produced in the fully mixed reactor is reduced by the amount of the monomer containing the (meth) acrylate ester. The average residence time divided by the supply amount is preferably 0.5 to 6 hours. By setting the average residence time within this range, stable polymerization can be performed, and a polymer excellent in molding processability tends to be produced. By making the stay time 0.5 hours or longer, it is not necessary to increase the amount of radical polymerization initiator used, so the amount of terminal double bonds in the (meth) acrylate polymer can be reduced, and heat decomposition There exists a tendency for the polymer excellent in property to be obtained. In addition, by making the average residence time 6 hours or less, the productivity of the (meth) acrylic acid ester polymer tends to be good, and the dimer of the monomer containing the (meth) acrylic acid ester There is a tendency to suppress the production of the body.

In the above continuous polymerization method, the reaction mixture (a) discharged from the complete mixing reactor is further polymerized in the plug flow reactor by connecting the complete mixing reactor to the plug flow reactor and the reaction mixture. Productivity can also be improved by obtaining (b). In the present invention, if necessary, a plurality of plug flow reactors can be connected in series.
Since the radical polymerization initiator and chain transfer agent added to the monomer containing (meth) acrylic acid ester remain in the reaction liquid (a) discharged from the complete mixing reactor, the plug flow type Polymerization proceeds only by holding in the reactor, but in order to polymerize with good productivity, it is preferable to supply a polymerization initiator and, if necessary, a chain transfer agent to the plug flow reactor. In addition, when supplying the polymerization initiator and, if necessary, the chain transfer agent to the plug flow reactor, it is necessary to mix the polymerization initiator and the chain transfer agent more uniformly with the reaction liquid (a). Accordingly, a static mixer can be connected in series before the plug flow reactor. When a plurality of plug flow reactors are used, a static mixer can be connected in series before each plug flow reactor as necessary.
The type of the plug flow reactor is not particularly limited, but a tube reactor equipped with a static mixer is preferable in order to achieve a simple and plug flow.

  The temperature of the reaction liquid (b) at the outlet of the plug flow reactor is preferably 170 to 200 ° C. By setting the temperature of the reaction liquid (b) to 170 ° C. or higher, the viscosity of the reaction liquid (b) tends to be an appropriate value that is not too high, and pressure loss in plug flow reactors and piping The pressure resistance of the device tends to be reduced to a low level. In addition, by setting the temperature of the reaction liquid (b) to 200 ° C. or less, the physical properties such as depolymerization of the (meth) acrylic acid ester polymer, transparency, mechanical strength, heat distortion temperature, and thermal decomposition resistance can be reduced. It tends to be suppressed.

  The polymerization rate of the reaction liquid (b) at the outlet of the plug flow reactor is preferably 50 to 85% in terms of industrially stable production. By setting the polymerization rate of the reaction liquid (b) at the outlet of the plug flow reactor to 85% or less, the viscosity of the reaction liquid tends to be an appropriate value that is not too high. The productivity tends to be improved by setting the polymerization rate of the reaction liquid (b) at the outlet of the liquid to 50% or more.

  The average staying time obtained by dividing the staying amount of the reaction solution (b) in the plug flow reactor by the supply amount of the reaction solution (a) is preferably 0.1 to 2 hours. By setting the average residence time to 0.1 hour or longer, it is not necessary to increase the amount of radical polymerization initiator used, so that the amount of terminal double bonds in the polymer can be reduced, and heavy heat resistance with excellent thermal decomposition resistance can be reduced. There is a tendency to combine. In addition, when the average residence time is 2 hours or less, the pressure loss in the plug flow reactor tends to be reduced, and the formation of a monomer dimer containing (meth) acrylate can be suppressed. There is a tendency.

  The amount of radical polymerization initiator used in the plug flow reactor can be arbitrarily adjusted according to the polymerization temperature, the average residence time, and the target polymerization rate. 0.001-1 mass part is preferable with respect to 100 mass parts of mass bodies. When the amount of the radical polymerization initiator used is 0.001 part by mass or more, the target polymerization rate tends to be obtained. Moreover, it exists in the tendency which can reduce raw material cost by making the usage-amount of a radical polymerization initiator into 1 mass part or less.

  The amount of chain transfer agent used in the plug flow reactor can be arbitrarily adjusted so as to achieve the target molecular weight, and is based on 100 parts by mass of the monomer containing (meth) acrylic acid ester. 0-2 mass parts is preferable. When the amount of the chain transfer agent used is 2 parts by mass or less, the target molecular weight tends to be obtained.

  As shown in step (2), the monomer mixture containing the (meth) acrylic acid ester polymer obtained in step (1) is supplied to a volatile matter removing apparatus, and the volatile matter is continuously separated and removed. In addition, a (meth) acrylic acid ester polymer can be obtained.

  Any device can be used as the volatile content removing device as long as it can separate and remove volatile content from the polymer and take out the (meth) acrylic acid ester polymer. Machine.

  The temperature for separating and removing the volatile component from the polymer in the volatile component removing apparatus may be the temperature obtained by polymerization, or may be further heated. In the case of further heating, the temperature of the (meth) acrylic acid ester polymer is preferably 250 ° C. or lower, more preferably 230 ° C. or lower, and further preferably 210 ° C. or lower. By setting the heating temperature to 250 ° C. or lower, the production of dimers tends to be suppressed. Moreover, it is preferable that the temperature of a (meth) acrylic acid ester polymer shall be 180 degreeC or more, and it is preferable to set it as 200 degreeC or more. By setting the heating temperature to 180 ° C. or higher, volatile components tend to be efficiently separated and removed.

  When using a devolatilizing extruder, the (meth) acrylic acid ester polymer is released under a reduced pressure of 0.0001 to 0.1 MPa, and most of the volatile content mainly composed of (meth) acrylic acid ester is continuously produced. It is preferable to remove them.

  As for content of the monomer containing the (meth) acrylic acid ester in the (meth) acrylic acid ester polymer obtained by isolate | separating and removing a volatile matter, 0.3 mass% or less is preferable. Further, the content of the monomer dimer containing (meth) acrylic acid ester in the (meth) acrylic acid ester polymer obtained by separating and removing volatiles is preferably 0.1% by mass or less. .

  The monomer containing unreacted (meth) acrylate ester in the separated and removed volatile matter is recovered by condensing with a condenser and then reused as the monomer containing (meth) acrylate ester It is preferable from the viewpoint of economy. At this time, high-boiling components such as (meth) acrylic acid ester dimers contained in the volatiles are separated by distillation and removed, and then reused as a monomer containing (meth) acrylic acid esters. Is more preferable.

  Since the monomer containing unreacted (meth) acrylic acid ester in the volatile matter separated and removed in step (2) contains a large amount of coloring-causing substances, the monomer containing (meth) acrylic acid ester As shown in step (4), before being reused as a monomer containing (meth) acrylic acid ester, purified by the (meth) acrylic acid ester purification method of the present invention shown in step (3) Is preferable from the viewpoint of removing the color-causing substance.

Hereinafter, the present invention will be described by way of examples. In the following, “part” means “part by mass”. Moreover, evaluation of the light absorbency of alcohol and (meth) acrylic acid ester and the yellowness of (meth) acrylic acid ester polymer was carried out by the following methods.
(1) Absorbance Absorbance was measured using a spectrophotometer (trade name: DR5000) manufactured by HACH. The absorbance of ion-exchanged water was used as a blank, the average value of absorbance at a wavelength of 380 to 500 nm was determined, and the absorbance was obtained.
(2) Yellowness The yellowness (YI) of the (meth) acrylic acid ester polymer was measured based on JIS-K7103 using a spectrophotometer (trade name: DR5000) manufactured by HACH.

[Example 1]
According to the flowchart shown in FIG. 1, as shown below, a molded body using a (meth) acrylic acid ester polymer obtained by a continuous production method was obtained.

  After introducing nitrogen into the monomer mixture 1 containing 93.7 parts of methyl methacrylate (MMA) and 6.3 parts of methyl acrylate (MA), 100 parts of this monomer mixture 1 and chain transfer agent 2 As a result, 0.39 part of n-octyl mercaptan was added to the monomer preparation tower. A raw material monomer obtained by mixing 0.01 parts of tert-butylperoxy-3,5,5-trimethylhexanate as a polymerization initiator to the obtained mixture was thoroughly mixed at a polymerization temperature of 135 ° C. A reaction in which a part of the raw material monomer is polymerized in the complete mixing reactor by continuously supplying it to the type reactor while stirring and mixing, and continuously extracting the reaction solution from the complete mixing reactor with a gear pump. A liquid was prepared. The reaction conditions of the raw material monomers in the complete mixing reactor were such that the residence amount of the reaction liquid was 5,000 kg and the average residence time was 2.5 hours.

  Subsequently, 100 parts of the reaction liquid discharged from the complete mixing reactor was used as a polymerization initiator 4 together with 0.002 part of tert-butylperoxy-3,5,5-trimethylhexanate as a polymerization initiator static mixer. 1 was supplied.

  Next, the reaction solution discharged from the static mixer 1 was supplied to the plug flow reactor 1.

  Subsequently, 100 parts of the reaction liquid discharged from the plug flow reactor 1 was supplied as a polymerization initiator 5 to a static mixer 2 for polymerization initiator together with 0.0015 part of di-tert-butyl peroxide.

  Further, the reaction liquid discharged from the static mixer 2 was supplied to the plug flow reactor 2.

  The jacket temperature of the plug flow reactor 2 was adjusted so that the temperature of the reaction solution discharged from the plug flow reactor 2 was 190 ° C.

  The reaction liquid discharged from the plug flow reactor 2 was supplied to a devolatilizing extruder and devolatilized to obtain a (meth) acrylic acid ester polymer. The polymerization rate of the (meth) acrylic acid ester polymer was 74%.

  Volatile matter discharged from the vent of the devolatilizing extruder was made liquid by cooling and condensation, and the volatile matter liquid a was supplied to the flash tank. A distillate obtained by continuously distilling the volatile liquid a in a flash tank was collected in an RM tank to obtain a collected liquid (RM) containing MMA.

A glass column having an inner diameter of 20 mm is filled with 30.0 g of Amberlyst XH2071 (trade name, manufactured by Dow Chemical Co., Ltd.), which is a strongly acidic cation exchange resin as a cation exchange resin. Step A, step B and step C shown in FIG.
(Process A)
Isopropanol (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) (hereinafter referred to as “IPA”) was used as the cleaning solvent A, and 78.0 ml (solvent amount ratio = 2.1) under SV2.1 conditions using a metering pump. ) Was continuously passed through the column.

  In the present invention, the solvent amount ratio indicates the ratio (V2 / V1) of the volume (V2) of the passed solvent to the empty volume (V1) of the cation exchange resin packed in the column.

  The flow rate of the cleaning solvent A can be calculated from the following equation.

Flow rate (ml / hr) = Cavity volume of cation exchange resin (ml) × SV (1 / hr)
Absorbance before washing of solvent A (α), flow temperature, SV, flow rate, solvent volume ratio, and solvent acid ratio The washing solvent A comes out of the column after contacting the strongly acidic cation exchange resin in an amount of solvent volume ratio 1. Table 1 shows the absorbance of the solvent A after washing.
(Process B)
Of the washing solvent flowing out from the column after contacting with the strongly acidic cation exchange resin in step A, 39.5 ml of the washing solvent A flowing out from the column after passing through 1 volume-volume is recovered, and the recovered solvent A is recovered. Obtained. The absorbance of the obtained recovered solvent A was measured. Next, 30.5 ml of IPA was added to 39.5 ml of the recovered solvent A thus obtained to prepare washing solvent B to be used in Step B. Next, 39.0 ml of washing solvent B was continuously passed through the column washed in step A under the conditions of SV2.1 using a metering pump, and the washed solvent B discharged from the column was recovered. Table 1 shows the absorbance of the washing solvent B, the liquid passing temperature, the SV, the liquid passing speed, the solvent amount ratio, and the absorbance of the solvent B after washing.
(Process C)
Using a metering pump, 39.0 ml of IPA as the washing solvent C was continuously passed through the column washed in Step B under the conditions of SV2.1, and the washed solvent C discharged from the column was recovered. Table 1 shows the absorbance of the washing solvent C, the liquid passing temperature, the SV, the liquid passing speed, the solvent amount ratio, and the absorbance of the solvent C after washing.

  A washing strongly acidic cation exchange resin was obtained through the washing steps of Step A, Step B and Step C.

  1.0 ml of the washed strongly acidic cation exchange resin is extracted from the column, and 5.0 ml of IPA (absorbance α) is added to prepare a washing strongly acidic cation exchange resin evaluation liquid, and left for 30 minutes. did. Next, the supernatant was collected, and the absorbance (β) after contact with the washed strongly acidic cation exchange resin was measured. The results are shown in Table 1. Absorbance (α) and absorbance (β) were at the same level, and the elution of the coloring component from the strongly acidic cation exchange resin after washing was not confirmed, and was sufficiently washed.

  While heating the aforementioned RM to 41 ° C., 39.0 ml was passed through the column packed with the washed strongly acidic cation exchange resin obtained in Step C under the conditions of SV2.1. The absorbance of RM after passing through was 0.05, and the elution of the coloring component from the washed strongly acidic cation exchange resin was not confirmed. Table 1 shows the RM purification conditions and evaluation results.

  Next, 0.012 g of tert-butylperoxy-3,5,5-trimethylhexanate was added to 6.0 g of RM purified with a washed strongly acidic cation exchange resin, and after bubbling with nitrogen, enclosed in a glass tube having an inner diameter of 10 mm did. The glass tube was allowed to react for 8 hours while heating to 80 ° C. in an oil bath. YI of the obtained polymer was 7.6.

XH2071: Strong acid cation exchange resin manufactured by Dow Chemical Co. IPA: manufactured by Wako Pure Chemical Industries, Ltd., special grade isopropanol MeOH: manufactured by Wako Pure Chemical Industries, Ltd., special grade methanol RM: recovered monomer

[Examples 2 to 4]
The cation exchange resin was washed, the (meth) acrylic acid ester was purified, and the cation exchange resin was washed in the same manner as in Example 1 except that the washing conditions of the cation exchange resin were the conditions of Step A, Step B and Step C shown in Table 1. Polymerization of the purified (meth) acrylic acid ester was carried out to obtain a polymer of (meth) acrylic acid ester. The obtained results are shown in Table 1.

[Example 5]
According to the flowchart shown in FIG. 2, as shown below, a molded body using a (meth) acrylic acid ester polymer obtained by a continuous production method was obtained.

The cation exchange resin tower was filled with 94.4 kg of Amberlyst XH2071 (trade name, manufactured by Dow Chemical Co., Ltd.) which is a strong acid cation exchange resin as a cation exchange resin. Each cleaning of the process A, the process B, and the process C shown was performed in order.
(Process A)
Using IPA as the washing solvent A and using an aired pump connected to a flow meter, 300 L (solvent amount ratio 2.0) of washing solvent A was continuously passed through the cation exchange resin tower under the condition of SV2.0. . Absorbance (α) of washing solvent A before washing, liquid passing temperature, SV, liquid passing speed, solvent amount ratio, and cation exchange resin after washing solvent A comes into contact with strongly acidic cation exchange resin in an amount of solvent amount ratio 1 Table 1 shows the absorbance of the solvent A after washing flowing out of the tower.
(Process B)
Of the washing solvent flowing out from the cation exchange resin tower after contacting with the strongly acidic cation exchange resin in step A, the post-washing solvent A163L flowing out from the cation exchange resin tower after passing through 1 volume-volume is recovered. Recovery solvent A was obtained. Subsequently, the recovered solvent A thus obtained is used as the washing solvent B as it is, and continuously passed through the cation exchange resin tower washed in step A under the conditions of SV2.0 using an air pump as in step A. did. Table 1 shows the absorbance of the washing solvent B, the liquid passing temperature, the SV, the liquid passing speed, the solvent amount ratio, and the absorbance of the solvent B after washing.
(Process C)
Using an air pump, 453 L of IPA as the washing solvent C was continuously passed through the cation exchange resin tower washed in Step B under the condition of SV2.0. Table 1 shows the absorbance of the washing solvent C, the liquid passing temperature, the SV, the liquid passing speed, the solvent amount ratio, and the absorbance of the solvent C after washing.

  A washing strongly acidic cation exchange resin was obtained through the washing steps of Step A, Step B and Step C described above. When the performance of the washed strongly acidic cation exchange resin was evaluated in the same manner as in Example 1, the absorbance (α) and absorbance (β) were at the same level as shown in Table 1.

  After introducing nitrogen into the monomer mixture 1 containing MMA 93.7 parts and MA 6.3 parts, 100 parts of the monomer mixture 1 and 0.39 parts of n-octyl mercaptan as the chain transfer agent 2 It was put into the adjustment tower. A raw material monomer obtained by mixing 0.01 part of tert-butylperoxy-3,5,5-trimethylhexanate as a polymerization initiator 3 with the obtained mixture was completely controlled at a polymerization temperature of 135 ° C. The mixture was continuously supplied to the mixing reactor while stirring and mixing, and the reaction liquid was continuously extracted from the complete mixing reactor with a gear pump, and a part of the raw material monomer was polymerized in the complete mixing reactor. A reaction solution was prepared. The reaction conditions of the raw material monomers in the complete mixing reactor were such that the residence amount of the reaction liquid was 5,000 kg and the average residence time was 2.5 hours.

  Subsequently, 100 parts of the reaction liquid discharged from the complete mixing type reactor was mixed with 0.002 part of tert-butylperoxy-3,5,5-trimethylhexanate as a polymerization initiator 4 for static polymerization for mixing the polymerization initiator. It was supplied to the mixer 1.

  Next, the reaction solution discharged from the static mixer 1 was supplied to the plug flow reactor 1.

  Subsequently, 100 parts of the reaction solution discharged from the plug flow reactor 1 was supplied as a polymerization initiator 5 to 0.0015 part of di-tert-butyl peroxide to the static mixer 2 for mixing the polymerization initiator.

  Further, the reaction liquid discharged from the static mixer 2 was supplied to the plug flow reactor 2.

  The jacket temperature of the plug flow reactor 2 was adjusted so that the temperature of the reaction solution discharged from the plug flow reactor 2 was 190 ° C.

  The reaction liquid discharged from the plug flow reactor 2 was supplied to a devolatilizing extruder and devolatilized to obtain a (meth) acrylic acid ester polymer. The polymerization rate of the (meth) acrylic acid ester polymer was 74%.

  The volatile component devolatilized from the vent of the devolatilizing extruder was made liquid by cooling and condensation, and the volatile component liquid a was supplied to the flash tank. The distillate b obtained by continuously distilling the volatile liquid a in a flash tank was collected in an RM tank to obtain a recovered liquid (RM) containing MMA. The amount of RM obtained was 1,950 kg / hr.

  17 parts of the above RM was supplied with 0.01 part of a polymerization inhibitor (2-tert-butyl-4,6-dimethylphenol) dissolved in 100 parts of MMA to obtain a purification RM. After heating to 40 ° C. with a heat exchanger, the solution was passed through the cation exchange resin tower packed with the washed strong acidic cation exchange resin at a flow rate of 85 kg / hr. The remaining 83 parts of RM were stored in the RM tank as they were.

  The RM discharged from the cation exchange resin tower was sent to a multistage distillation tower (17-stage turbo grid tray) and continuously distilled under the conditions of a supply flow rate of 85 kg / hr and a reflux ratio of 1.4. The distillate from the top of the multistage distillation column was mixed with the remaining 83 parts of RM and sent to the monomer preparation column.

  In the continuous production apparatus for the (meth) acrylic acid ester polymer, the production of the (meth) acrylic acid ester polymer is one cycle from the introduction of the monomer mixture, and the second and subsequent cycles are recovered by a devolatilizing extruder. Using RM as a monomer mixture, the (meth) acrylic acid ester polymer after 20 cycles was molded with an injection molding machine to obtain a molded body. The obtained molded product had a YI of 0.6.

[Example 6]
A glass column having an inner diameter of 20 mm was packed with 30.1 g of strongly acidic cation exchange resin Amberlyst XH2071. Further, as a cleaning method for the strongly acidic cation exchange resin Amberlyst XH2071, Step A and Step B were omitted, and only Step C was cleaned. The strongly acidic cation exchange resin was washed in the same manner as in Example 1 except that 117 ml of IPA was used as the washing solvent C as the washing condition in Step C to obtain a washed strongly acidic cation exchange resin. Table 1 shows the absorbance of the washing solvent C (absorbance (α)), liquid passing temperature, superficial velocity, liquid passing speed, solvent amount ratio, and absorbance of the solvent C after washing.

  Using the obtained washed strongly acidic cation exchange resin, a washing strong acid cation exchange resin evaluation liquid was prepared in the same manner as in Example 1, and the absorbance (β) after contacting the washed strongly acidic cation exchange resin was measured. did. The results are shown in Table 1.

  39.0 ml of RM obtained in the same manner as in Example 1 was purified using a washed strongly acidic cation exchange resin under the conditions shown in Table 1. The results are shown in Table 1.

  A polymer was obtained in the same manner as in Example 1 using 6.0 ml of RM purified with a washed strongly acidic cation exchange resin. YI of the obtained polymer was 9.5.

[Comparative Example 1]
Washing strong acid obtained in the same manner as in Example 1 except that the strongly acidic cation exchange resin shown in Table 1 was used, and the washing conditions of the strong acid cation exchange resin were washed only in Step A shown in Table 1. The performance of the washed strongly acidic cation exchange resin was evaluated under the conditions shown in Table 1 using the cationic cation exchange resin. The results are shown in Table 1.

  39.0 ml of RM obtained in the same manner as in Example 1 was purified using a washed strongly acidic cation exchange resin under the conditions shown in Table 1. The results are shown in Table 1.

A polymer was obtained in the same manner as in Example 1 using 6.0 ml of RM purified with a washed strongly acidic cation exchange resin. The resulting polymer had a YI of 30.8 and was quite colored.

Claims (15)

  A method for purifying a (meth) acrylate ester by contacting a (meth) acrylate ester with a cation exchange resin, wherein the cation exchange resin is an alcohol whose volume is one volume with respect to the empty volume of the cation exchange resin. (Meth) acrylic acid ester purification method in which the absorbance (β) of alcohol after washing the cation exchange resin with 1 satisfies the requirement of 1 or less. The cation exchange resin has an alcohol absorbance (β) after washing the cation exchange resin with 1 volume of alcohol relative to the empty volume of the cation exchange resin and the alcohol before washing the cation exchange resin. The method for purifying a (meth) acrylic acid ester according to claim 1, wherein the light absorbency (α) satisfies the requirement of the following formula (1).
0 ≦ [absorbance (β)] − [absorbance (α)] ≦ 0.1 (1) The method for purifying a (meth) acrylic acid ester according to claim 1 or 2, wherein the cation exchange resin is washed by a method comprising the following steps A, B and C in order.
(Step A): A washing step in which an alcohol having an absorbance of 2 or less is brought into contact with the cation exchange resin at least 1 volume by volume with respect to the empty volume of the cation exchange resin.
(Step B): A washing step in which an alcohol satisfying the following conditions B1 and B2 is brought into contact with the cation exchange resin at least 1 volume by volume with respect to the empty volume of the cation exchange resin.
(Condition B1): The absorbance is equal to or less than the absorbance of a mixture of alcohols flowing out from the time when the volume of alcohol is brought into contact with the empty volume of the cation exchange resin in Step A to the end of Step A.
(Condition B2): The alcohol which wash | cleaned the cation exchange resin is contained.
(Step C): A washing step of washing the cation exchange resin with an alcohol having an absorbance of 0.5 or less until the absorbance of the alcohol after washing the cation exchange resin becomes 0.5 or less.   The method for purifying a (meth) acrylic acid ester according to any one of claims 1 to 3, wherein the alcohol is at least one selected from methanol, ethanol, 1-propanol and isopropanol.   The method for purifying a (meth) acrylic acid ester according to claim 3 or 4, wherein the alcohol used in (Step B) contains 1 to 100 vol% of alcohol obtained by washing the cation exchange resin.   The method for purifying a (meth) acrylic acid ester according to any one of claims 1 to 5, wherein the cation exchange resin is a strongly acidic cation exchange resin.   The method for purifying a (meth) acrylic acid ester according to any one of claims 1 to 6, wherein the degree of crosslinking of the cation exchange resin is 5 to 20%.   (Meth) acrylic acid ester is methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol (meth) Acrylate, neopentyl glycol di (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, allyl (meth) acrylate, (meth) acrylic acid 2 The method for purifying a (meth) acrylic acid ester according to any one of claims 1 to 7, comprising at least one selected from -hydroxyethyl.   The amount of alcohol used for washing is 2.5 to 10 volume times the empty volume of the cation exchange resin in one washing, (meth) according to any one of claims 1 to 8 A method for purifying acrylic ester.   The method for purifying a (meth) acrylic acid ester according to any one of claims 1 to 9, wherein the washing time of the cation exchange resin with alcohol is 0.2 to 5 hours per step.   The method for purifying a (meth) acrylic acid ester according to any one of claims 1 to 10, wherein the temperature of the alcohol used for washing is 5 to 60 ° C.   The (meth) acrylic acid ester according to any one of claims 1 to 11, wherein the (meth) acrylic acid ester has a temperature of 10 to 60 ° C when the (meth) acrylic acid ester and the cation exchange resin are brought into contact with each other. Method.   The purification rate of the (meth) acrylic acid ester according to any one of claims 1 to 12, wherein a superficial velocity when the methacrylic acid ester is brought into contact with the cation exchange resin is 0.2 to 10 [1 / hr]. Method.   The manufacturing method of the (meth) acrylic acid ester polymer which polymerizes the monomer containing the (meth) acrylic acid ester refine | purified with the purification method in any one of Claims 1-13. It is a manufacturing method of the continuous (meth) acrylic acid ester polymer containing following process (1)-process (4), Comprising: Process (3) is (meth) acrylic acid in any one of Claims 1-13 The manufacturing method of the continuous (meth) acrylic acid ester polymer which is the refinement | purification method of ester.
Step (1): A step of polymerizing a part of a monomer containing a (meth) acrylic acid ester to obtain a monomer mixture containing a (meth) acrylic acid ester polymer.
Step (2): A step of removing a monomer containing (meth) acrylic acid ester from the monomer mixture obtained in (1) to obtain a (meth) acrylic acid ester polymer.
Step (3): recovering the monomer containing the (meth) acrylic acid ester removed in (2), purifying the recovered (meth) acrylic acid ester, and purifying the (meth) acrylic acid ester Obtaining a monomer containing.
Step (4): The monomer containing the purified (meth) acrylic acid ester obtained in (3) is added as at least part of the monomer containing the (meth) acrylic acid ester in step (1). Process.