JP5008155B2 - Acrylic resin production method, acrylic resin, and molded article - Google Patents

Description

  The present invention provides a method for producing an acrylic resin capable of improving the solvent resistance and impact resistance while suppressing the generation of agglomerates and the like produced during production and maintaining workability. The present invention relates to an acrylic resin and a molded body thereof.

Acrylic resins represented by polymethyl methacrylate (PMMA) are widely used in the fields of optical materials, vehicle parts, building materials, lenses, household items, OA equipment, lighting equipment, etc. due to their high transparency. ing. In particular, in recent years, the use for vehicle materials and optical materials such as light guide plates and liquid crystal display films has progressed, and the use of conventional acrylic resins that makes molding difficult has increased. For example, when injection molding a large and thin molded product, if the fluidity of the resin is poor, the injection pressure is insufficient and molding cannot be performed, or the molded product is greatly distorted. Therefore, a highly fluid resin that can be molded even when the injection pressure is low is desired. On the other hand, further improvement in solvent resistance and mechanical strength is also demanded.
Conventionally, as a known method for improving the mechanical strength and moldability of acrylic resins, there is a method of imparting fluidity with a low molecular weight acrylic resin and imparting mechanical strength with a high molecular weight or a micro-crosslinked structure. Are known. In connection with this, techniques for melting and mixing high molecular weight or low molecular weight acrylic resins and expanding the molecular weight distribution using a branched structure have been reported. (For example, see Patent Documents 1, 2, and 3).
However, the acrylic resin described in Patent Document 1 only mixes two different molecular weight acrylic resins and does not satisfy both high fluidity and mechanical strength at the same time. Patent Document 2 describes a technique in which a low molecular weight acrylic resin is copolymerized in a large amount with another vinyl monomer copolymerizable with methyl methacrylate. However, the flowability of the resulting acrylic resin is insufficient.

In the method for producing a slightly crosslinked methacrylic resin using a polyfunctional monomer described in Patent Document 3, there is a problem that it is very difficult to control the polyfunctional monomer. When the amount of the polyfunctional monomer is too large, the mixing uniformity is lowered and the appearance of the molded product is lowered. On the other hand, if the amount of the polyfunctional monomer is too small, there is no effect of improving fluidity and maintaining mechanical strength.
Patent Document 4 discloses a technique for improving fluidity while maintaining mechanical strength as compared with a conventional acrylic resin by using a multistage polymerization method. Although this technique made it possible to improve the properties of the resulting polymer, the amount of aggregates sometimes increased during polymerization. When the aggregates increase, a decrease in chromaticity may be observed, and when the aggregates are removed, the yield decreases. Therefore, a reduction in the amount of aggregates during polymerization is required. In addition, if the amount of monomer remaining in the acrylic resin increases, molding defects such as silver marks called silver may remain in the molded product when the resulting acrylic resin is molded. There is also a demand for a reduction in the amount of monomer to be used.

Japanese Patent Publication No. 1-2865 JP-A-4-277545 Japanese Patent Laid-Open No. 9-207196 International Publication Number 2007/060891 Pamphlet

  This invention provides the manufacturing method which can suppress the production | generation of the aggregate at the time of manufacture, and can also reduce the amount of remaining monomers about the acrylic resin holding high fluidity | liquidity.

  As a result of intensive studies to solve these problems, the inventors of the present invention, when producing an acrylic resin having high fluidity, add the raw material for the first stage reaction and then increase the exothermic peak temperature due to polymerization exotherm. By performing the polymerization within a specific time difference after making the time until confirmation longer than the time until the exothermic peak temperature due to the polymerization exotherm is confirmed after adding the raw material for the second and subsequent reactions, It has been found that the amount of aggregates in the resulting polymer can be reduced, and the present invention has been completed.

That is, the present invention is as follows.
[1] A method for producing an acrylic resin containing a methacrylic acid ester, comprising 80 to 100% by weight of a methacrylic acid ester monomer, and methyl acrylate, ethyl acrylate, n-propyl acrylate, n-acrylic acid - butyl, butyl sec- acrylate, at least one or more vinyl monomers 20-0 feedstock containing mass% selected from 2-ethylhexyl acrylate, the weight average molecular weight measured by gel permeation chromatography After the polymer (I) of 5000 to 50000 is produced in an amount of 5 to 45% by mass based on the whole acrylic resin, a methacrylic acid ester monomer and methyl acrylate in the presence of the polymer (I) , Ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec-butyl acrylate, Was added a raw material containing at least one or more vinyl monomers selected from acrylic acid 2-ethylhexyl 95 polymer having a weight average molecular weight of 60,000 to 350,000 and (II) for the entire the acrylic resin A method for producing an acrylic resin, characterized by producing 55% by mass, wherein T1 is a time from when a raw material of the polymer (I) is added until an exothermic peak temperature due to polymerization exotherm is observed, A method for producing an acrylic resin, characterized in that the following formula (1) is established, where T2 is the time from when the raw material of the combined (II) is added until the exothermic peak temperature due to polymerization exotherm is observed.
0.6 <T2 / T1 <1 (1)

[2] The acrylic according to 1 above, wherein a time T2 from when the raw material of the polymer (II) is added to when the exothermic peak temperature due to the polymerization exotherm is observed is 40 minutes or more and 180 minutes or less. Method for production of resin.
[3] The method for producing an alkaline resin as described in 1 or 2 above, which is produced by a suspension polymerization method.
[4] The above 1-3, wherein the vinyl monomer is at least one vinyl monomer selected from methyl acrylate, ethyl acrylate, and n-butyl acrylate.
The manufacturing method of acrylic resin as described in any one of these.
[5] The method for producing an acrylic resin according to any one of the above items 1 to 4, wherein the vinyl monomer is methyl acrylate.
[6] The method for producing an acrylic resin according to any one of the above 1 to 5, wherein the methacrylic acid ester monomer as a raw material of the polymer (I) is methyl methacrylate.

The present invention has high productivity because it can suppress the formation of aggregates when producing an acrylic resin having high fluidity, impact resistance, and solvent resistance, and remains in the resin. The present invention provides a method for producing an acrylic resin with a small amount of monomer.

It is explanatory drawing regarding the GPC area of the methacryl resin obtained with the manufacturing method of this invention. It is the figure which showed an example of the accumulation area area on a GPC elution curve measurement graph. It is a figure which shows the position of the accumulation area area on a GPC elution curve measurement graph.

Although the manufacturing method of the acrylic resin of this invention is demonstrated in detail below, this invention is not limited to these aspects.
In the present invention, the monomer component before polymerization is referred to as “˜monomer”, but “monomer” may be omitted. Moreover, the structural unit which comprises a polymer is called "-monomer unit."
The acrylic resin obtained by the production method of the present invention is obtained by polymerizing at least a methacrylic acid ester monomer, and can be copolymerized with the methacrylic acid ester monomer as long as the effects of the present invention can be exhibited. Other vinyl monomers may be copolymerized.

<Methacrylate monomer>
The methacrylic acid ester monomer that can be used in the present invention is not particularly limited as long as the effects of the present invention can be achieved, but preferred examples include monomers represented by the following general formula (2). It is done.

However, R1 represents a methyl group. R2 represents a group having 1 to 12 carbon atoms, and may have a hydroxyl group on the carbon.
Specific examples of methacrylic acid ester monomers that can be suitably used include butyl methacrylate, ethyl methacrylate, methyl methacrylate, propyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, methacrylic acid (2 -Ethylhexyl), methacrylic acid (t-butylcyclohexyl), benzyl methacrylate, methacrylic acid (2,2,2-trifluoroethyl), and the like. Methyl methacrylate is easy to obtain.
The methacrylic acid ester monomers can be used alone or in combination of two or more.
Moreover, the said methacrylic acid ester monomer may use the same thing for a polymer (I) and a polymer (II), and may use a different thing.

<Other vinyl monomers>
In addition to the above-mentioned methacrylic acid ester monomer, for the purpose of improving the properties such as heat resistance, optical properties, processability, etc., it is advisable to add a vinyl monomer as appropriate to copolymerize the resulting polymer. . As an example, an acrylate monomer represented by the following general formula (3)

(Wherein R3 is a hydrogen atom and R4 is an alkyl group having 1 to 18 carbon atoms), α, β-unsaturated acids such as acrylic acid and methacrylic acid, maleic acid, fumaric acid, itaconic acid Unsaturated divalent carboxylic acids such as cinnamic acid and their alkyl esters, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, Styrene units such as 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, о-ethylstyrene, p-tert-butylstyrene, isopropenyl benzene (α-methylstyrene) 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenyltoluene, isopropenylethyl Benzene, isopropenyl propyl benzene, isopropenyl butylbenzene, isopropenyl point pen chill benzene, isopropenyl hexyl benzene, aromatic vinyl compounds such as isopropenyl-octyl benzene, acrylonitrile, vinyl cyanide compounds such as methacrylonitrile;

Unsaturated carboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, maleimide, N-substituted maleimides such as N-methylmaleimide, N-ethylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide, etc., acrylamide, methacrylic Amide such as amide, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, etc. Esterified with acrylic acid or methacrylic acid, hydroxyl group of two alcohols such as those esterified with acrylic acid or methacrylic acid, neopentyl glycol di (meth) acrylate, di (meth) acrylate, etc. Of trimethylol propane, which polyhydric alcohol derivatives such as pentaerythritol was esterified with acrylic acid or methacrylic acid, the polyfunctional monomer such as divinylbenzene exemplified.

Preferably, from the viewpoint of enhancing light resistance, heat resistance, fluidity, and thermal stability, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec-butyl acrylate, 2-acrylic acid 2- Ethylhexyl or the like is used. Methyl acrylate, ethyl acrylate, and n-butyl acrylate are more preferable, and methyl acrylate is most preferable because it is easily available.
The vinyl monomers can be used alone or in combination of two or more.
Moreover, the said vinyl-type monomer may use the same thing for a polymer (I) and a polymer (II), and may use a different thing.

<Composition ratio of monomer>
In the above monomer, the composition ratio of the polymer (I) and the polymer (II) in the acrylic resin is 5 to 45% by mass of the polymer (I), and the polymer (II) is 95 to 55% by mass. It is preferable to use it so that it may become%. By being this composition ratio, the polymerization stability at the time of manufacture can be aimed at, and the fluidity | liquidity at the time of setting it as acrylic resin and the mechanical strength of a resin molding can also be improved. Considering a further balance of polymerization stability, fluidity and mechanical strength of the molded product, the ratio of polymer (I) / (II) is preferably 5 to 40% by mass / 95 to 55% by mass, more preferably 5%. It is -35 mass% / 95-65 mass%, Most preferably, it is 10-35 mass% / 90-65 mass%.

When another vinyl monomer is added to the methacrylic acid ester monomer as a raw material for the polymer (I), the composition ratio of the methacrylic acid ester monomer to the other vinyl monomer is as follows. It is preferable that a vinyl-type monomer is 20-0 mass% with respect to 80-100 mass% of bodies. More preferably, it is 90-100 mass% / 10-0 mass%, More preferably, it is 95-100 mass% / 5-0 mass%.
When it is particularly necessary to consider the polymerization stability, the amount of the acrylate monomer in the other copolymerizable vinyl monomer in the polymer (I) is substantially zero. In this case, the amount of the methacrylic acid ester monomer that is the raw material is allowed to be present as an impurity.

In the present invention, when another vinyl monomer is added to the methacrylic acid ester monomer as a raw material for the polymer (II), the composition ratio of the methacrylic acid ester monomer to the other vinyl monomer is It is preferable that it is 80-99.5 mass% / 20-0.5 mass%. More preferably, it is 85-99.5 mass% / 15-0.5 mass%, More preferably, it is 90-99 mass% / 10-1 mass%.
The addition amount of the other vinyl monomer in the acrylic resin is preferably 1.5 to 20% by mass with respect to the acrylic resin. This range is preferable because fluidity and heat resistance are improved. More preferably, it is 1.5-17 mass%, More preferably, it is 2-15 mass%.

The weight average molecular weight of the polymer (I) is such that the weight average molecular weight measured by gel permeation chromatography is 5,000 to 50,000 from the viewpoint of suppressing defects such as silver at the time of molding, polymerization stability, and imparting fluidity. preferable. More preferably, it is 10000-50000, More preferably, it is 20000-50000.
When it is necessary to particularly consider the polymerization stability, it is preferable that the amount of the acrylate monomer in the other copolymerizable vinyl monomers is substantially zero. The amount contained as an impurity in the methacrylic acid ester monomer as a raw material is allowed.
The weight average molecular weight of the polymer (II) is preferably 60000-350,000 from the viewpoint of mechanical strength and fluidity. More preferably, it is 70000-320,000, More preferably, it is 75000-300000.

  In the present invention, the blending ratio of the methacrylic acid ester monomer and the other vinyl monomer copolymerizable with the polymer (II) is not particularly defined as long as the effect of the present application can be exhibited. It is preferable that methacrylic acid ester monomer / other vinyl monomer is 80 to 99.5 mass% / 20 to 0.5 mass%. More preferably, it is 85-99.5 mass% / 15-0.5 mass%, More preferably, it is 90-99 mass% / 10-1 mass%.

<Ratio of other vinyl monomers in polymer (I) and polymer (II)>
In the present invention, the copolymerization ratio of the other vinyl monomer units copolymerizable with the methacrylic acid ester in the polymer (I) and the polymer (II) is particularly defined as long as the effect of the present application can be exhibited. The composition ratio of other vinyl monomer units copolymerizable with the methacrylic acid ester of the polymer (I) is Mal (mass%), and other copolymerizable with the methacrylic acid ester of the polymer (II). When the composition ratio of the vinyl monomer unit is Mah (mass%), it is preferable that the relationship of the following formula (4) is satisfied from the viewpoint of polymerization stability.
Mah ≧ Mal ≧ 0 (4)
When the polymer (II) having a high molecular weight contains a large amount of other vinyl monomers copolymerizable with methacrylic acid esters as a composition ratio, not only can the polymerization stability be improved, but also heat resistance and mechanical strength can be improved. This is preferable because the fluidity can be improved while maintaining. More preferably, the relationship of the following formula (5) is established.
(Mah-0.8) ≧ Mal ≧ 0 (5)

In the acrylic resin obtained by the production method according to the present invention, when a molded body is used, it is required to improve the fluidity while maintaining the mechanical strength while reducing the rate of occurrence of cracks and distortion of molded products in environmental tests. The range of the following formula (6) is preferable.
(Mah-2) ≧ Mal ≧ 0 (6)
The amounts of the composition ratios Mal and Mah can be determined by measuring each of the polymer (I) and the polymer (II) by pyrolysis gas chromatography. In order to adjust the composition ratios Mal and Mah to the above ranges, the amount of other vinyl monomers copolymerizable with the methacrylic acid ester monomer added during the first and second and subsequent polymerizations is adjusted. do it.

<Manufacturing method>
The method for producing the acrylic resin in the present invention is not particularly limited as long as it is a method suitable for the multistage polymerization method. As the multistage polymerization method, any of bulk polymerization, solution polymerization, suspension polymerization method or emulsion polymerization method is preferable. More preferred are bulk polymerization, solution polymerization and suspension polymerization, and further preferred is suspension polymerization.
A methacrylate ester polymer obtained by polymerizing a methacrylate ester monomer or a methacrylate ester monomer and another vinyl monomer copolymerizable with at least one methacrylate ester in the first stage polymerization step (I) (hereinafter simply referred to as polymer (I)) is obtained in the second and subsequent polymerization steps, in the presence of the polymer (I), a methacrylic acid ester monomer and at least one methacrylic acid. Other vinyl monomers copolymerizable with the ester are added to produce polymer (II) (hereinafter simply referred to as polymer (II)). This is because this polymerization method makes it easy to control the composition of each of the polymer (I) and the polymer (II), suppresses a temperature rise due to heat generated during polymerization, and stabilizes the viscosity in the system. .
The monomer of the polymer (II) may be added in a state where the polymerization is partially started before the polymerization of the polymer (I) is completed.

<Polymerization time>
In the method for producing an acrylic resin of the present invention, from the viewpoint of suppressing aggregates and reducing the amount of residual monomers, the polymerization time of the polymer (I), that is, the polymerization heat generated after the addition of the raw material in the first stage polymerization. The relationship between the time to reach the exothermic peak temperature (T1) and the polymerization time of the polymer (II), that is, the time (T2) to reach the exothermic peak temperature due to the polymerization exotherm after the addition of the raw material in the second and subsequent stages, The following relational expression (1) needs to hold.
0.6 <T2 / T1 <1 (1)
Preferably 0.65 <T2 / T1 <1, more preferably 0.7 <T2 / T1 <1, still more preferably 0.75 <T2 / T1 <1, and particularly preferably 0.75. <T2 / T1 <0.95, and particularly preferably 0.8 ≦ T2 / T1 <0.95. In order to adjust the time required to reach the exothermic peak temperatures in the first stage and the second stage as shown in the relational expression (1), the quantity ratio also depends on the polymerization ratio of the polymer (I) and the polymer (II). However, the amount of the polymerization initiator to be used may be appropriately adjusted to an optimal amount.
The polymerization temperature may be produced by appropriately selecting an optimum polymerization temperature according to the polymerization method, and is preferably 50 ° C. or higher and 180 ° C. or lower.

<Production example by suspension polymerization>
As an example, the production method in the suspension polymerization method will be described in detail below.
The polymerization temperature in the present invention is preferably 60 ° C. or higher and 90 ° C. or lower in consideration of productivity and the amount of aggregates produced. More preferably, it is 65 degreeC or more and 85 degrees C or less, More preferably, it is 70 degreeC or more and 85 degrees C or less, Most preferably, it is 75 degreeC or more and 85 degrees C or less.
The polymerization temperature of the polymer (I) and the polymer (II) may be the same or different.
Even in the case where the suspension polymerization method is employed, the conditions are such that the relationship of the above formula (1) is satisfied. Within this range, the amount of aggregates produced can be reduced, and the productivity tends to be improved from the viewpoint that the amount of residual monomer in the resulting acrylic resin is reduced.
The time (T1) from the addition of the raw material of the polymer (I) to the arrival of the exothermic peak temperature due to the polymerization exotherm may be within the range in which the effect of the present invention can be exhibited, but preferably 60 minutes or more and 270 minutes. The following is recommended. More preferably, they are 70 minutes or more and 240 minutes or less, More preferably, they are 70 minutes or more and 180 minutes or less, Especially preferably, they are 70 minutes or more and 170 minutes or less, Especially preferably, they are 70 minutes or more and 150 minutes or less.

The raw material of the polymer (II) may be added immediately after an exothermic peak due to the polymerization of the polymer (I) is observed, or may be added after being kept for a certain time. When it is necessary to increase the degree of polymerization of the raw material of the polymer (I), after the exothermic peak due to the polymer (I) is observed, hold for a certain period of time, and then supply the raw material of the polymer (II) It is preferable to do.
The holding time is not particularly specified, but is preferably 10 minutes or more and 180 minutes or less, more preferably 15 minutes or more and 150 minutes or less, still more preferably 20 minutes or more and 150 minutes or less, more preferably 30 minutes or more and 140 minutes or less. .
Since the temperature at the time of holding can raise the degree of polymerization, it is preferably the same as the polymerization temperature of the polymer (I) or higher than the polymerization temperature of the polymer (I). Is preferably raised from the polymerization temperature by 5 ° C. or more. The temperature elevation temperature is preferably 100 ° C. or less from the viewpoint of preventing aggregation of the resulting polymer. Specifically, it is preferably 80 ° C or higher and 100 ° C or lower, more preferably 80 ° C or higher and 99 ° C or lower, still more preferably 85 ° C or higher and 99 ° C or lower, particularly preferably 88 ° C or higher and 99 ° C or lower, particularly preferably 90 ° C. It is not lower than 99 ° C and not higher than 99 ° C.

In the present invention, the temperature (T2) from the addition of the raw material of the polymer (II) to the observation of the exothermic peak temperature due to the polymerization exotherm may be within the range where the effects of the present invention can be exhibited, but preferably Is from 40 minutes to 180 minutes, more preferably from 45 minutes to 160 minutes, further preferably from 50 minutes to 150 minutes, particularly preferably from 50 minutes to 140 minutes, particularly preferably from 60 minutes to 120 minutes. is there.
After the exothermic peak temperature due to the polymerization exotherm is observed after adding the raw material of the polymer (II), the amount of residual monomer in the resulting acrylic resin can be reduced, so that the polymerization of the polymer (II) It is preferable to raise the temperature by 5 ° C or more than the temperature, more preferably 7 ° C or more, and further preferably 10 ° C or more. Further, in order to prevent aggregation of the obtained resin, the temperature to be raised is 100 ° C. or lower, and a preferable range is 85 ° C. or higher and 100 ° C. or lower, more preferably 90 ° C. or higher and 99 ° C. or lower, and further preferably 92 ° C. or higher and 99 ° C. or lower. It is as follows.

The holding time after the temperature rise is not particularly defined as long as the effect of the present application can be exhibited, but it is preferable to hold the temperature for a certain period of time. Specifically, it is 10 minutes to 180 minutes, preferably 15 minutes to 150 minutes, more preferably 20 minutes to 120 minutes, and more preferably 30 minutes to 90 minutes.
It is preferable that the amount of aggregates produced during production is small. Considering productivity and colorless transparency of the resulting resin, it is preferably 1.4% or less, more preferably 1.2% or less, still more preferably 1.0% or less, and particularly preferably 0.8%. It is as follows.
In addition, when the amount of the monomer remaining in the acrylic resin is large, the production amount is decreased, and when the heat history is applied by extrusion, molding, etc., the colorless transparency tends to be impaired. Moreover, since there is a possibility that silvery marks (silver) may be generated in the molded body at the time of molding, the smaller one is preferable. Specifically, it is 1.0% or less, more preferably 0.9% or less, still more preferably 0.8% or less, particularly preferably 0.7% or less, particularly preferably 0.6% or less. It is. By appropriately adjusting the conditions within the above production method, the amount of aggregates and remaining monomers can be kept low.

<Polymerization initiator>
In the present invention, a polymerization initiator may be used for the purpose of adjusting the degree of polymerization of the polymer to be produced. In the present invention, examples of polymerization initiators that can be used include di-t-butyl peroxide, lauroyl peroxide, stearyl peroxide, benzoyl peroxide, and t-butyl peroxyneo when radical polymerization is performed. Decanate, t-butylperoxypivalate, dilauroyl peroxide, dicumyl peroxide, t-butylperoxy-2-ethylhexanoate, 1,1-bis (t-butylperoxy) -3,3 Organic peroxides such as 1,5-bis (t-butylperoxy) cyclohexane, azobisisobutyronitrile, azobisisovaleronitrile, 1,1-azobis (1-cyclohexanecarbox) Nitrile) 2,2'-azobis-4-methoxy-2,4-azo Azo-based general radical polymerization initiators such as sisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, 2,2′-azobis-2-methylbutyronitrile can be listed. . These may be used alone or in combination of two or more. A combination of these radical initiators and an appropriate reducing agent may be used as a redox initiator. These initiators are generally used in the range of 0 to 1 part by mass with respect to 100 parts by mass of the total amount of all monomers used, considering the polymerization temperature and the half-life of the initiator. Can be selected as appropriate.

When selecting a bulk polymerization method, a cast polymerization method or a suspension polymerization method, from the viewpoint of resin colorability and water resistance, the peroxide initiators lauroyl peroxide, decanoyl peroxide, and t-butylperoxy- 2-ethylhexanoate and the like can be particularly preferably used, and lauroyl peroxide is particularly preferably used.
In addition, when the solution polymerization method is performed at a high temperature of 90 ° C. or higher, a peroxide, an azobis initiator, or the like that has a 10-hour half-life temperature of 80 ° C. or higher and is soluble in the organic solvent to be used is preferable. Specifically, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, cyclohexane peroxide, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, , 1-azobis (1-cyclohexanecarbonitrile), 2- (carbamoylazo) isobutyronitrile and the like. These initiators are preferably used, for example, in the range of 0 to 1 part by mass with respect to 100 parts by mass of the total amount of all monomers used.

<Molecular weight control>
In the present invention, the molecular weight of the acrylic resin to be produced can be controlled within a range that does not impair the object of the present invention. For example, the molecular weight can be controlled by using chain transfer agents such as alkyl mercaptans, dimethylacetamide, dimethylformamide and triethylamine, and iniferters such as dithiocarbamates, triphenylmethylazobenzene and tetraphenylethane derivatives. The molecular weight can be adjusted by adjusting the amount of these additives. When these additives are used, alkyl mercaptans are preferably used from the viewpoint of handleability and stability. For example, n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-tetra Examples include decyl mercaptan, n-octadecyl mercaptan, 2-ethylhexyl thioglycolate, ethylene glycol dithioglycolate, trimethylolpropane tris (thioglycolate), pentaerythritol tetrakis (thioglycolate), and the like.

These can be appropriately added according to the required molecular weight, but generally used in the range of 0.001 to 3 parts by mass with respect to 100 parts by mass of the total amount of all monomers used. .
Examples of other molecular weight control methods include a method of changing the polymerization method, a method of adjusting the amount of the polymerization initiator, and a method of changing the polymerization temperature.
These molecular weight control methods may be used alone, or two or more methods may be used in combination.

<Rules of the resulting acrylic resin>
Hereinafter, the acrylic resin obtained by the above production method will be described.
As for the molecular weight of the acrylic resin obtained by the above method, the weight average molecular weight measured by gel permeation chromatography (GPC) is 60000-300000. An acrylic resin in this range is excellent in mechanical strength and fluidity. Considering the balance of fluidity, mechanical strength, and solvent resistance, it is preferably 60000-250,000 or less, more preferably 80000-230,000.
The molecular weight distribution (weight average molecular weight / number average molecular weight: Mw / Mn) is preferably 2.4 ≦ Mw / Mn ≦ 5 considering the balance between fluidity, mechanical strength, and solvent resistance.
The weight average molecular weight and number average molecular weight measured in the present invention are measured by gel permeation chromatography (GPC) as described above. A calibration curve is prepared in advance from the elution time and the weight average molecular weight using a monodispersed standard methacrylic resin having a known weight average molecular weight and available as a reagent, and an analytical gel column that elutes a high molecular weight component first. The molecular weight of each sample can be obtained from the obtained calibration curve.

The acrylic resin obtained in the present invention is a peak present in the acrylic resin from the viewpoint of improving moldability and suppressing distortion of the molded product after molding, plasticizing effect, fluidity, heat resistance, and crack control in environmental tests. It is preferable that the abundance of a weight molecular weight component of 1/5 or less of the weight average molecular weight (Mp) is 7 to 40%. More preferably, it is 8-35%, More preferably, it is 8-30%. However, since the methacrylic resin component having a weight average molecular weight of 500 or less tends to cause a foam-like appearance defect called silver at the time of molding, it is preferably as small as possible.
Here, the peak weight average molecular weight (Mp) refers to the weight average molecular weight showing a peak in the GPC elution curve. When there are a plurality of peaks in the GPC elution curve, the peak is indicated by the weight-average molecular weight having the largest abundance.

  Moreover, the area area in the GPC elution curve mentioned later refers to the shaded portion shown in FIG. The specific method is as follows. First, point A and point B where the baseline automatically drawn by the measuring instrument and the GPC elution curve intersect with the GPC elution curve obtained from the elution time obtained by GPC measurement and the detected intensity by RI (differential refraction detector). Determine. Point A is a point where the GPC elution curve at the beginning of the elution time and the baseline intersect. Point B is a position where, as a general rule, the weight average molecular weight is 500 or more and the baseline and the GPC elution curve intersect. If the weight average molecular weight does not intersect within the range of 500 or more, the value of RI detection intensity at the elution time when the weight average molecular weight is 500 is defined as point B. A hatched portion surrounded by the GPC elution curve between the points A and B and the line segment AB is an area in the GPC elution curve. This area is the area of the GPC elution curve. In this application, since a column eluted from a high molecular weight component is used, a high molecular weight component is observed at the beginning of the elution time, and a low molecular weight component is observed at the end of the elution time.

The cumulative area area (%) of the area area in the GPC elution curve is point 0 shown in FIG. 2 being 0% which is the standard of the cumulative area area (%), and the detection corresponding to each elution time is directed toward the end of the elution time The view is that the intensity accumulates and an area area in the GPC elution curve is formed. A specific example of the accumulated area area is shown in FIG. In FIG. 2, a point on the baseline at a certain elution time is a point X, and a point on the GPC elution curve is a point Y. The ratio of the area enclosed by the curve AX, the line segment AB, and the line segment XY to the area area in the GPC elution curve is the value of the accumulated area area (%) at a certain elution time.
Let Mh (wt%) be the average composition ratio of other vinyl monomer units copolymerizable with a methacrylic acid ester in a methacrylic resin having a weight average molecular weight component in a cumulative area of 0 to 2%. On the other hand, an average composition ratio of other vinyl monomer units copolymerizable with a methacrylic acid ester in a methacrylic resin having a cumulative area area of 98 to 100%, that is, a low molecular weight is defined as Ml (wt%). FIG. 3 shows a schematic diagram of positions on the measurement graph of the accumulated area area of 0 to 2% and 98 to 100%.

The values of Mh and Ml can be obtained by fractionating several times or several tens of times according to the column size based on the elution time obtained from GPC. The composition of the collected sample may be analyzed by a known pyrolysis gas chromatography method.
It is preferable that the relationship of the following formula (7) is established between Mh (wt%) and Ml (wt%) in the present invention.
(Mh−0.8) ≧ Ml ≧ 0 (7)
This indicates that the high molecular weight component has an average composition of 0.8 wt% or more of other vinyl monomer units copolymerizable with the methacrylic acid ester than the low molecular weight component. The low molecular weight component indicates that other vinyl monomers do not necessarily have to be copolymerized. The difference between Mh (wt%) and Ml (wt%) is preferably 0.8 wt% or more for the effect of improving fluidity. More preferably, it is 1.0 wt%, and more preferably, the following formula (8) is satisfied.
(Mh-2) ≧ Ml ≧ 0 (8)
That is, by increasing the average composition of other vinyl monomer units copolymerizable with the acrylic resin methacrylic acid ester in the high molecular weight component by 2 wt% or more than the average composition of the low molecular weight component, This is preferable because a dramatic improvement in fluidity can be obtained while maintaining a low occurrence rate of cracks and distortion of molded products and mechanical strength.

<Polymer (I) (II) contained in acrylic resin>
The polymer (I) contained in the acrylic resin is a monomer composed of 80 to 100 wt% of a methacrylic acid ester monomer and at least one other vinyl monomer copolymerizable with the methacrylic acid ester. It is a polymer composed of 0 to 20 wt%. The amount of other vinyl monomers copolymerizable with the methacrylic acid ester is preferably small, and may not be used.
The polymer (II) is a monomer 0.5 composed of 80 to 99.5% by mass of a methacrylic acid ester monomer and at least one other vinyl monomer copolymerizable with the methacrylic acid ester. It is a polymer composed of ˜20% by mass.

<Combination with other resins>
The acrylic resin produced according to the present invention can be used in combination with conventionally known resins. The resin to be used is not limited at all, and a known curable resin or thermoplastic resin is preferably used. For example, the thermoplastic resins include polypropylene resins, polyethylene resins, polystyrene resins, syndiotactic polystyrene resins, ABS resins, acrylic resins, AS resins, BAAS resins, MBS resins, AAS. Resins, biodegradable resins, polycarbonate-ABS resin alloys, polybutylene terephthalate, polyethylene terephthalate, polypropylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate and other polyalkylene arylate resins, polyamide resins, polyphenylene ether resins, polyphenylene Examples thereof include sulfide resins and phenol resins. In particular, AS resin and BAAS resin are preferable for improving fluidity, ABS resin and MBS resin are preferable for improving impact resistance, and polyester resin is preferable for improving chemical resistance. In addition, polyphenylene ether resins, polyphenylene sulfide resins, phenol resins, and the like can be expected to have an effect of improving flame retardancy.

Further, as curable resins, unsaturated polyester resins, vinyl ester resins, diallyl phthalate resins, epoxy resins, cyanate resins, xylene resins, triazine resins, urea resins, melamine resins, benzoguanamine resins, urethane resins, oxetane resins, ketone resins. Alkyd resin, furan resin, styrylpyridine resin, silicone resin, synthetic rubber and the like.
These resins may be used alone or in combination of two or more.

<Additives>
In order to impart other properties such as rigidity and dimensional stability to the acrylic resin produced in the present invention, various additives such as phthalate ester-based, fatty acid ester-based within the range not impairing the effects of the present invention , Trimellitic acid ester type, phosphoric acid ester type, polyester type plasticizer, higher fatty acid, higher fatty acid ester, higher fatty acid mono-, di- or triglyceride type release agent, polyether type, polyether ester type , Polyether ester amides, alkyl sulfonates, alkyl benzene sulfonates and other antistatic agents, antioxidants, UV absorbers, heat stabilizers, light stabilizers and other stabilizers, flame retardants, flame retardant aids , Curing agent, curing accelerator, conductivity imparting agent, stress relaxation agent, crystallization accelerator, hydrolysis inhibitor, lubricant, impact imparting agent, slidability improving agent Compatibilizer, nucleating agent, reinforcing agent, reinforcing agent, flow regulator, dye, sensitizer, coloring pigment, rubber polymer, thickener, anti-settling agent, anti-sagging agent, filler, antifoaming agent Coupling agents, rust inhibitors, antibacterial / antifungal agents, antifouling agents, conductive polymers, and the like can be added.

  Examples of the heat stabilizer that can be added to the acrylic resin produced in the present invention include antioxidants such as hindered phenol antioxidants and phosphorus processing stabilizers, preferably hindered phenols. It is an antioxidant. Specifically, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionate, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N′-hexane-1,6-diylbis [3- (3,5-di-tert-butyl) -4-hydroxyphenylpropionamide, 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-tert-butyl-a, a ′, a ″-(mesitylene-2,4,6- Triyl) tri-p-cresol, 4,6-bis (octylthiomethyl) -o-cresol, 4,6-bis (dodecylthiomethyl) -o-cresol, ethyl Bis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate, hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 1,3 , 5-tris [(4-tert-butyl-3-hydroxy-2,6-xylin) methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 2, 6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamine) phenol and the like, more preferably pentaerythritol [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

  Examples of ultraviolet absorbers that can be added to the acrylic resin produced in the present invention include benzotriazole compounds, benzotriazine compounds, benzoate compounds, benzophenone compounds, oxybenzophenone compounds, phenol compounds, and oxazole compounds. Examples include compounds, malonic acid ester compounds, cyanoacrylate compounds, lactone compounds, salicylic acid ester compounds, benzoxazinone compounds, and preferred are benzotriazole compounds and benzotriazine compounds. These may be used alone or in combination of two or more.

In addition, when an ultraviolet absorber is added to the acrylic resin produced in the present invention, a vapor pressure (P) at 20 ° C. of 1.0 × 10 ⁻⁴ Pa or less is preferable from the viewpoint of moldability. More preferably, it is 1.0 × 10 ⁻⁶ Pa or less, and particularly preferably 1.0 × 10 ⁻⁸ Pa or less. “Excellent molding processability” means, for example, that there is little adhesion of the ultraviolet absorber to the roll during film formation. If it adheres to the roll, for example, it may adhere to the surface of the molded body and deteriorate the appearance and optical properties, so it is not preferred when the molded body is used as an optical material.
Moreover, it is preferable that melting | fusing point (Tm) of an ultraviolet absorber is 80 degreeC or more, More preferably, it is 100 degreeC or more, More preferably, it is 130 degreeC or more, Most preferably, it is 160 degreeC or more.
The UV absorber that can be added in the present invention preferably has a weight loss rate of 50% or less, more preferably 30% or less when the temperature is increased from 23 ° C. to 260 ° C. at a rate of 20 ° C./min. More preferably, it is 15% or less, more preferably 10% or less, and particularly preferably 5% or less.

<Additives and other resin kneading methods>
The kneading method for processing the acrylic resin produced according to the present invention or mixing with various additives or other resins may be a conventionally known method, and is not particularly defined. For example, it can be kneaded and produced using a kneader such as an extruder, a heating roll, a kneader, a roller mixer, a Banbury mixer and the like. Among these, kneading with an extruder is preferable in terms of productivity. The kneading temperature may be in accordance with the preferred processing temperature of the acrylic resin produced according to the present invention and other resins to be mixed, and is generally in the range of 140 to 300 ° C, preferably in the range of 180 to 280 ° C.

<Molding method>
Moreover, it can be set as a molded object by shape | molding the acrylic resin manufactured by this invention individually or the resin composition containing this.
The acrylic resin produced by the present invention or a resin composition containing the same is formed by injection molding, sheet molding, blow molding, injection blow molding, inflation molding, T-die molding, press molding, extrusion molding, foam molding, casting method. The film can be formed by a known method such as film forming, and a secondary process forming method such as pressure forming or vacuum forming can also be used.
Moreover, when using the resin composition which mix | blended curable resin with the acrylic resin manufactured by this invention, the component for manufacturing a resin composition can be uniformly, without a solvent, or as needed. After mixing using a solvent that can be mixed, the solvent is removed to obtain a resin composition, which is cast into a mold, cured, cooled, and then taken out of the mold to obtain a molded product. . It can also be cast into a mold and cured by hot pressing. The solvent for dissolving each component is not particularly limited as long as various materials can be mixed uniformly and the effects of the present invention are not impaired by use. Examples include toluene, xylene, acetone, methyl ethyl ketone, methyl butyl ketone, diethyl ketone, cyclopentanone, cyclohexanone, dimethylformamide, methyl cellosolve, methanol, ethanol, n-propanol, iso-propanol, n-butanol, n-pen. Examples include tanol, n-hexanol, cyclohexanol, n-hexane, and n-pentane.

  Another example is a method in which a resin composition is kneaded and manufactured using a kneader such as a heating roll, kneader, Banbury mixer, extruder, etc., then cooled, pulverized, and further molded by transfer molding, injection molding, compression molding, or the like. Can be mentioned. The curing method varies depending on the curing agent used, but is not particularly limited. Examples include thermal curing, light curing, UV curing, pressure curing, moisture curing, and the like. The order of mixing the components is not particularly limited as long as the effect of the present invention can be achieved.

<Application>
The molded product using acrylic resin produced according to the present invention includes household products, OA equipment, AV equipment, battery electrical equipment, lighting equipment, automotive parts use, housing use, sanitary use, liquid crystal display, plasma Light guide plate, diffuser plate, polarizing plate protective film, 1/4 wavelength plate, 1/2 wavelength plate, viewing angle control film, liquid crystal optical compensation used in displays such as displays, organic EL displays, field emission displays, rear projection televisions Examples thereof include a retardation film such as a film, a display front plate, a display substrate, a lens, a touch panel and the like, and can be suitably used for a transparent substrate used for a solar cell. In addition, in the fields of optical communication systems, optical switching systems, and optical measurement systems, they can also be used for waveguides, lenses, optical fibers, optical fiber coating materials, LED lenses, lens covers, and the like. It can also be used as a modifier for other resins.
The molded body using the acrylic resin produced according to the present invention can be subjected to surface functionalization treatment such as antireflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, and gas barrier treatment.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the following examples.
[material]
The raw materials used are as follows.
Methyl methacrylate: manufactured by Asahi Kasei Chemicals (2.5 ppm of 2,4-di-6-tert-butylphenol) is added as a polymerization inhibitor )
Methyl acrylate: manufactured by Mitsubishi Chemical (added with 14 ppm of 4-methoxyphenol manufactured by Kawaguchi Chemical Industry as a polymerization inhibitor)
n-octylmercaptan: made by Arkema 2-ethylhexyl thioglycolate: made by Arkema lauroyl peroxide: made by Nippon Oil & Fats Co., Ltd. Used as a suspending agent Calcium calbonate: manufactured by Shiraishi Kogyo Co., Ltd. used as a suspending agent sodium lauryl sulfate: manufactured by Wako Pure Chemical Industries, Ltd. used as a suspending aid

[Measurement method]
[I. Measurement of resin composition and molecular weight]
1. Composition analysis of methacrylic resin The composition analysis of methacrylic resin was performed by pyrolysis gas chromatography and mass spectrometry.
Pyrolysis device: PY-2020D made by FRONTIER LAB
Column: DB-1 (length 30 m, inner diameter 0.25 mm, liquid phase thickness 0.25 μm)
Column temperature program: held at 40 ° C. for 5 min, then raised to 320 ° C. at a rate of 50 ° C./min, held at 320 ° C. for 4.4 minutes Pyrolysis furnace temperature: 550 ° C.
Column inlet temperature: 320 ° C
Gas chromatography: Agilent GC6890
Carrier: pure nitrogen, flow rate 1.0 ml / min
Injection method: Split method (split ratio 1/200)
Detector: JEOL mass spectrometer Automass Sun
Detection method: Electron impact ionization method (ion source temperature: 240 ° C., interface temperature: 320 ° C.)
Sample: 10 μl of 10 g chloroform solution of 0.1 g methacrylic resin
The sample was collected in a platinum sample cup for a pyrolysis apparatus, vacuum dried at 150 ° C. for 2 hours, and then placed in a pyrolysis furnace, and the composition analysis of the sample was performed under the above conditions. The composition ratio of the methacrylic resin was determined based on the peak area on total ion chromatography (TIC) of methyl methacrylate and methyl acrylate and the calibration curve of the following standard sample.

  Preparation of standard sample for calibration curve: The ratio of methyl methacrylate and methyl acrylate is (methyl methacrylate / methyl acrylate) = (100% / 0%), (98% / 2%), (94% / 6% ), (90% / 10%) (80% / 20%), respectively, 0.25% lauroyl peroxide and 0.25% n-octyl mercaptan were added to 50 g of each of the five solutions. Each of these mixed solutions was put into a 100 cc glass ampule bottle, and the air was replaced with nitrogen and sealed. The glass ampoule bottle was placed in an 80 ° C. water bath for 3 hours and then in an oven at 150 ° C. for 2 hours. After cooling to room temperature, the glass was crushed and the methacrylic resin inside was taken out and subjected to composition analysis. A graph of (methyl acrylate area value) / (methyl methacrylate area value + methyl acrylate area value) and methyl acrylate charge ratio obtained by measurement of a standard sample for a calibration curve is used as a calibration curve. It was.

2. Measurement of weight-average molecular weight of methacrylic resin Measuring device: Gel analysis chromatography (LC-908) manufactured by Nippon Analysis Industry
Column: 1 JAIGEL-4H and 2 JAIGEL-2H in series connection In this column, the high molecular weight elutes early, and the low molecular weight elutes slowly.
Detector: RI (differential refraction) detector Detection sensitivity: 2.4 μV / sec
Sample: 0.450 g of methacrylic resin in chloroform 15 ml Injection amount: 3 ml
Developing solvent: chloroform, flow rate 3.3 ml / min
Under the above conditions, the RI detection intensity with respect to the elution time of the methacrylic resin was measured. The average molecular weight of the methacrylic resin was determined based on the area area in the GPC elution curve and the calibration curve.
The following 10 methacrylic resins (manufactured by EasiCal PM-1 Polymer Laboratories) having different molecular weights and known monodispersed weight average molecular weights were used as standard samples for calibration curves.
Weight average molecular weight
Standard sample 1 1,900,000
Standard sample 2 790,000
Standard sample 3 281,700
Standard sample 4 144,000
Standard sample 5 59,800
Standard sample 6 28,900
Standard sample 7 13,300
Standard sample 8 5,720
Standard sample 9 1,936
Standard sample 10 1,020
When the polymer (I) and the polymer (II) are mixed, the GPC elution curve of the polymer (I) alone is measured in advance to obtain the weight average molecular weight, and the polymer (I) is present. GPC elution in which the polymer (I) and the polymer (II) are mixed by multiplying the GPC elution curve of the polymer (I) by the ratio (the charge ratio used in this application) By drawing from the curve, a GPC elution curve of the polymer (II) alone is obtained. From this, the weight average molecular weight of the polymer (II) was determined.

[II. Measurement of aggregate production]
The mixed solution containing the polymer fine particles obtained by the polymerization is passed through a 1.68 mm mesh sieve to remove the fine particle aggregates, and the obtained aggregates are dried in a drying oven at 80 ° C. for 12 hours. It was measured. The obtained weight was divided by the total amount of the raw material (I) and the raw material (II) to calculate the aggregate production amount (%).
[III. Measurement of average particle size]
Based on JIS-Z8801, JTS-200-45-33 (opening 500 μm), 34 (opening 425 μm), 35 (opening 355 μm), 36 (opening 300 μm), 37 (opening 250 μm) , 38 (aperture 150 μm) 61 (a saucer), using a measured value of an average particle diameter when sieving for 10 minutes with a vibration force MAX using a screening tester TSK B-1, 50 wt% The particle diameter was measured to determine the average particle diameter.

[IV. Measurement of residual monomer amount]
The residual monomer amount of each component was analyzed using a gas chromatography GC-1700 manufactured by Shimadzu Corporation, and the total amount was calculated.
[V. Physical property measurement]
1. Measurement of spiral length This is a test for determining the relative fluidity based on the distance that resin flows through a spiral cavity with a constant cross-sectional area.
Injection molding machine: Toshiba Machine IS-100EN
Mold for measurement: Mold having a groove with a depth of 2 mm and a width of 12.7 mm dug in the Archimedes spiral shape from the center of the surface on the mold surface Injection conditions Resin temperature: 250 ° C.
Mold temperature: 55 ° C
Injection pressure: 98 MPa
Injection time: 20 sec
Resin was injected into the center of the mold surface under the above conditions. After 40 seconds from the end of injection, the spiral molded product was taken out, and the length of the spiral portion was measured. This was used as an index for liquidity evaluation.
2. Transparency Based on the ISO 13468-1 standard, the total light transmittance was measured using a 3 mm-thick test piece, and used as an index of transparency.

[Example 1]
2 kg of water, 65 g of tricalcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate were added to a container having a stirrer to obtain a mixed solution (A). Next, 26 kg of water was charged into a 60 L reactor, the temperature was raised to 80 ° C., and the raw material of the polymer (I) was charged in the mixed liquid (A) and the blending amounts shown in Table 1. Thereafter, suspension polymerization was performed while maintaining the temperature at about 80 ° C., and an exothermic peak was observed 120 minutes after the starting material of the polymer (I) was added.
Then, it hold | maintained at 80 degreeC for 50 minute (s), and superposition | polymerization was complete | finished. Next, the raw materials for the polymer (II) were charged into the reactor at the blending amounts shown in Table 1, followed by suspension polymerization while maintaining the temperature at about 80 ° C. After the raw materials for the polymer (II) were charged, An exothermic peak was observed after 80 minutes. Thereafter, the temperature was raised to 92 ° C. at a rate of 1 ° C./min and then aged for 60 minutes to substantially complete the polymerization reaction. Next, 20 wt% sulfuric acid was added in order to cool to 50 ° C. and dissolve the suspending agent. Next, the polymerization reaction solution was passed through a 1.68 mm mesh sieve to remove aggregates, and the resulting bead polymer was washed and dehydrated and dried to obtain polymer fine particles.

The aggregates were dried in a drying oven at 80 ° C. for 12 hours and weighed. The weight was divided by the total amount of the raw material (I) and the raw material (II), and the aggregate production amount (%) was measured. The residual monomer amount was 0.49%. Moreover, the average particle diameter of the obtained polymer fine particles was 0.31 mm.
The obtained polymer fine particles were melt-kneaded with a φ30 mm twin screw extruder set at 240 ° C., and the strands were cooled and cut to obtain resin pellets. The weight average molecular weight of the obtained pellet was 132,000, and the molecular weight distribution was 2.4. The spiral length was 23.8 cm. The total light transmittance was 92%.

[Example 2]
2 kg of water, 65 g of tricalcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate were added to a container having a stirrer to obtain a mixed solution (A). Next, 26 kg of water was charged into a 60 L reactor, the temperature was raised to 80 ° C., and the raw material of the polymer (I) was charged in the mixed liquid (A) and the blending amounts shown in Table 1. Thereafter, suspension polymerization was performed while maintaining the temperature at about 80 ° C., and an exothermic peak was observed 100 minutes after the starting material of the polymer (I) was added.
Then, it hold | maintained at 80 degreeC for 70 minute (s), and superposition | polymerization was complete | finished. Next, the raw materials for the polymer (II) were charged into the reactor at the blending amounts shown in Table 1, followed by suspension polymerization while maintaining the temperature at about 80 ° C. After the raw materials for the polymer (II) were charged, An exothermic peak was observed after 80 minutes. Thereafter, the temperature was raised to 92 ° C. at a rate of 1 ° C./min and then aged for 60 minutes to substantially complete the polymerization reaction. Next, 20 wt% mineral acid was added in order to cool to 50 ° C. and dissolve the suspending agent. Next, the polymerization reaction solution was passed through a 1.68 mm mesh sieve to remove aggregates, and the resulting bead polymer was washed and dehydrated and dried to obtain polymer fine particles.

The aggregates were dried in a drying oven at 80 ° C. for 12 hours and weighed. The weight was divided by the total amount of the raw material (I) and the raw material (II), and the aggregate production amount (%) was measured. The residual monomer amount was 0.62%. Further, the average particle size of the obtained polymer fine particles was 0.32 mm.
The obtained polymer fine particles were melt-kneaded with a φ30 mm twin screw extruder set at 240 ° C., and the strands were cooled and cut to obtain resin pellets. The weight average molecular weight of the obtained pellet was 114,000, and the molecular weight distribution was 2.4. The spiral length was 30.8 cm. The total light transmittance was 92%.

Example 3
2 kg of water, 65 g of tricalcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate were added to a container having a stirrer to obtain a mixed solution (A). Next, 26 kg of water was charged into a 60 L reactor, the temperature was raised to 80 ° C., and the raw material of the polymer (I) was charged in the mixed liquid (A) and the blending amounts shown in Table 1. Thereafter, suspension polymerization was performed while maintaining the temperature at about 80 ° C., and an exothermic peak was observed 90 minutes after the starting material of the polymer (I) was added.
Then, it hold | maintained at 80 degreeC for 60 minute (s), and superposition | polymerization was complete | finished. Next, the raw materials for the polymer (II) were charged into the reactor at the blending amounts shown in Table 1, followed by suspension polymerization while maintaining the temperature at about 80 ° C. After the raw materials for the polymer (II) were charged, An exothermic peak was observed after 85 minutes. Thereafter, the temperature was raised to 92 ° C. at a rate of 1 ° C./min and then aged for 60 minutes to substantially complete the polymerization reaction. Next, 20 wt% sulfuric acid was added in order to cool to 50 ° C. and dissolve the suspending agent. Next, the polymerization reaction solution was passed through a 1.68 mm mesh sieve to remove aggregates, and the resulting bead polymer was washed and dehydrated and dried to obtain polymer fine particles.

The aggregates were dried in a drying oven at 80 ° C. for 12 hours and weighed. The weight was divided by the total amount of the raw material (I) and the raw material (II), and the aggregate production amount (%) was measured. The residual monomer amount was 0.56%. Further, the average particle size of the obtained polymer fine particles was 0.32 mm.
The obtained polymer fine particles were melt-kneaded with a φ30 mm twin screw extruder set at 240 ° C., and the strands were cooled and cut to obtain resin pellets. The weight average molecular weight of the obtained pellet was 116,000, and the molecular weight distribution was 3.5. The spiral length was 33.4 cm. The total light transmittance was 92%.

Example 4
2 kg of water, 65 g of tricalcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate were added to a container having a stirrer to obtain a mixed solution (A). Next, 26 kg of water was charged into a 60 L reactor, the temperature was raised to 80 ° C., and the raw material of the polymer (I) was charged in the mixed liquid (A) and the blending amounts shown in Table 1. Thereafter, suspension polymerization was carried out while maintaining the temperature at about 80 ° C., and an exothermic peak was observed 130 minutes after the starting material of the polymer (I) was added.
Then, it hold | maintained at 80 degreeC for 50 minute (s), and superposition | polymerization was complete | finished. Next, the raw materials for the polymer (II) were charged into the reactor at the blending amounts shown in Table 1, followed by suspension polymerization while maintaining the temperature at about 80 ° C. After the raw materials for the polymer (II) were charged, An exothermic peak was observed after 120 minutes. Thereafter, the temperature was raised to 92 ° C. at a rate of 1 ° C./min and then aged for 60 minutes to substantially complete the polymerization reaction. Next, 20 wt% sulfuric acid was added in order to cool to 50 ° C. and dissolve the suspending agent. Next, the polymerization reaction solution was passed through a 1.68 mm mesh sieve to remove aggregates, and the resulting bead polymer was washed and dehydrated and dried to obtain polymer fine particles.

The aggregates were dried in a drying oven at 80 ° C. for 12 hours and weighed. The weight was divided by the total amount of the raw material (I) and the raw material (II), and the aggregate production amount (%) was measured. The residual monomer amount was 0.51%. Moreover, the average particle diameter of the obtained polymer fine particles was 0.31 mm.
The obtained polymer fine particles were melt-kneaded with a φ30 mm twin screw extruder set at 240 ° C., and the strands were cooled and cut to obtain resin pellets. The weight average molecular weight of the obtained pellet was 175,000, and the molecular weight distribution was 3.8. The spiral length was 26.1 cm. The total light transmittance was 92%.

Example 5
2 kg of water, 65 g of tricalcium phosphate, 39 g of calcium carbonate, and 0.39 g of sodium lauryl sulfate were added to a container having a stirrer to obtain a mixed solution (A). Next, 26 kg of water was charged into a 60 L reactor, the temperature was raised to 80 ° C., and the raw material of the polymer (I) was charged in the mixed liquid (A) and the blending amounts shown in Table 1. Thereafter, suspension polymerization was performed while maintaining the temperature at about 80 ° C., and an exothermic peak was observed 100 minutes after the starting material of the polymer (I) was added. Thereafter, the temperature was raised to 92 ° C. at a rate of 1 ° C./min, and then maintained at a temperature of 92 ° C. to 94 ° C. for 30 minutes. Thereafter, the temperature was lowered to 80 ° C. at a rate of 1 ° C./min, and then the raw material of the polymer (II) was added to the reactor in the blending amount shown in Table 1, followed by suspension polymerization while maintaining about 80 ° C. And an exothermic peak was observed 75 minutes after adding the polymer (II) raw material. Thereafter, the temperature was raised to 92 ° C. at a rate of 1 ° C./min and then aged for 60 minutes to substantially complete the polymerization reaction. Next, 20 wt% sulfuric acid was added in order to cool to 50 ° C. and dissolve the suspending agent. Next, the polymerization reaction solution was passed through a 1.68 mm mesh sieve to remove aggregates, and the resulting bead polymer was washed and dehydrated and dried to obtain polymer fine particles.

  The aggregates were dried in a drying oven at 80 ° C. for 12 hours and weighed. The weight was divided by the total amount of the raw material (I) and the raw material (II), and the aggregate production amount (%) was measured. The residual monomer amount was 0.62%. Moreover, the average particle diameter of the obtained polymer fine particles was 0.31 mm.

[Comparative Examples 1-4]
Using the raw materials shown in Table 1, polymerization was carried out in the same manner as in Examples 1 to 4 except that only the polymerization time was changed (the same monomer charge composition having the same Example number and Comparative Example number), and polymer. Fine particles were obtained. Table 3 shows the measurement results of the polymerization time, the aggregate generation amount, the residual monomer amount, the particle diameter of the polymer fine particles, and the spiral length. In Comparative Examples 1 and 2, the polymer fine particles tend to become clogged at the inlet during molding.

  When Examples and Comparative Examples are compared, when T2 / T1 is 1 or more as in Comparative Examples 1 and 2, although the amount of aggregates can be reduced, the amount of residual monomer tends to increase exceeding 1.0%. It is in. Moreover, when T2 / T1 is 0.6 or less as in Comparative Examples 3 and 4, although the amount of residual monomer is small, the amount of aggregates exceeds 1.0% and tends to increase. As in the examples, the amount of residual monomer can be reduced in a well-balanced manner by forming the amount of aggregate and the amount of residual monomer by controlling the polymerization time of the first stage and the polymerization time of the second stage within the range of the present application. Moreover, even if it superposes | polymerizes with the same composition, in an Example, it turns out that fluidity | liquidity is better.

  By using the acrylic resin of the present invention, display (device) windows of mobile phones, liquid crystal monitors, liquid crystal televisions, etc., light guide plates used in liquid crystal displays, front plates of display devices, foreheads of pictures, etc., external light Windows, display signboards, exteriors of carport roofs, sheets on display shelves, covers and gloves for lighting fixtures, molded products with secondary processing such as pressure forming, vacuum forming, blow molding, etc. While maintaining appearance quality in automotive optical parts used in tail lamps and headlamps that are thin, large, and require durability to solvents such as alcohol-based cleaning agents, waxes, and wax removers, Providing molded products with improved molding characteristics during molding, while suppressing the occurrence of defects such as bent or cracked parts in environmental tests. It is possible to become.

Claims (6)

A method for producing an acrylic resin containing a methacrylic acid ester unit, comprising 80 to 100% by weight of a methacrylic acid ester monomer, and methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate From a raw material containing 20 to 0% by mass of at least one vinyl monomer selected from sec-butyl acrylate and 2-ethylhexyl acrylate, the weight average molecular weight measured by gel permeation chromatography is 5,000 to 5,000. The polymer (I) of 50000 is produced in an amount of 5 to 45% by mass with respect to the entire acrylic resin, and further in the presence of the polymer (I), a methacrylic acid ester monomer, methyl acrylate, acrylic acid Ethyl, n-propyl acrylate, n-butyl acrylate,
A raw material containing at least one vinyl monomer selected from sec-butyl acrylate and 2-ethylhexyl acrylate is added, and the weight average molecular weight is 60000-350,000.
A method for producing an acrylic resin, characterized in that the polymer (II) is produced in an amount of 95 to 55% by mass with respect to the entire acrylic resin, and after adding the raw material of the polymer (I) The time until the exothermic peak temperature due to the polymerization exotherm is observed is T1, and the time from when the polymer (II) raw material is added until the exothermic peak temperature due to the polymerization exotherm is observed is T2. Formula (1) is satisfied, The manufacturing method of acrylic resin characterized by the above-mentioned.
0.6 <T2 / T1 <1 (1) 2. The acrylic resin according to claim 1, wherein a time T2 from when the raw material of the polymer (II) is added to when an exothermic peak temperature due to polymerization exotherm is observed is 40 minutes or more and 180 minutes or less. Manufacturing method. 3. The method for producing an acrylic resin according to claim 1, wherein the acrylic resin is produced by a suspension polymerization method. The vinyl monomer is at least one vinyl monomer selected from methyl acrylate, ethyl acrylate, and n-butyl acrylate.
The manufacturing method of acrylic resin as described in any one of these. The method for producing an acrylic resin according to any one of claims 1 to 4, wherein the vinyl monomer is methyl acrylate. The method for producing an acrylic resin according to any one of claims 1 to 5, wherein a methacrylic acid ester monomer as a raw material of the polymer (I) is methyl methacrylate.