KR20050044175A - Preparing method for transparent resin by bulk polymerization - Google Patents

Abstract

The present invention relates to a method for producing a transparent resin having excellent chemical resistance and excellent processability and fluidity. In the method for preparing a transparent resin, a mixture of a reaction medium, a styrene-based monomer, a methyl methacrylate monomer and an acrylonitrile-based monomer is provided. The present invention provides a method for producing a transparent resin, characterized in that the addition of an organic peroxide initiator having a bifunctional group as an initiator to the bulk polymerization, the transparent resin produced by the production method of the present invention has excellent chemical resistance, processability and fluidity There is.

Description

Manufacturing method of transparent resin using bulk polymerization {Preparing Method for Transparent Resin by Bulk Polymerization}

The present invention relates to a method for producing a transparent resin having excellent chemical resistance and excellent processability and fluidity. In particular, in the method for preparing a transparent resin, a reaction medium, a styrene monomer, a methyl methacrylate monomer and an acrylonitrile monomer An organic peroxide initiator having a bifunctional group as an initiator is added to the mixture to bulk polymerize.

Generally, methods for preparing transparent resins include emulsion polymerization, turbid polymerization, solution polymerization, and bulk polymerization. As is well known among them, emulsion polymerization and suspension polymerization should use emulsifiers, viscosity enhancers, flocculants, etc. in the polymerization process, and these added substances are not removed in the final stage and remain as impurities in the final product. do. In addition, after the polymerization is completed, the reaction medium has to go through additional processes such as dehydration and flocculation or drying to remove water, and the removed water has to be purified again, which is an economically expensive production process.

On the contrary, the solution polymerization or the bulk polymerization method is difficult to control the heat of reaction or the viscosity of the reaction solution, but since there are no additives used for the polymerization, there are few impurities remaining in the final product so that the physical properties are excellent, and the reaction medium used after the polymerization is used. Phosphorus solvent and unreacted monomers are all recovered and used again, so unlike the emulsion polymerization or suspension polymerization, the production cost is low.

In general, polystyrene, which is widely used, is widely used as a food packaging container because of its transparency, excellent processability and fluidity, but recently, a material having better transparency, chemical resistance, and colorability of food packaging containers has been required. Currently, resins prepared by polymerizing methyl methacrylate are widely used as optical materials because of their excellent transparency. However, this resin has a disadvantage in that the polymerization rate is high and the viscosity of the polymerization solution is high, making it difficult to prepare by solution polymerization or bulk polymerization, and worse than polystyrene.

In addition, styrene-acrylonitrile copolymer is widely used as a material having excellent chemical resistance and colorability, but this resin has a disadvantage in that heat discoloration occurs well and transparency is poor.

In order to solve the above problems, a method for preparing a transparent resin by adding a methacryl-based monomer having excellent transparency has been developed. Patents related to this include Japanese Patent Application Publication No. 2001-31833 and Japanese Patent Application Publication No. 2002-114886. However, these two patents are intended to produce a transparent resin having excellent impact resistance by compounding a styrene-based monomer, a methyl methacrylate monomer, and an acrylonitrile monomer, and then polymerizing it with a rubber component. Resin was prepared for the purpose of transparency only without consideration of fluidity or chemical resistance, there was still a problem in terms of chemical resistance and fluidity.

In order to solve the above problems, the present invention is to provide a method for producing a transparent resin excellent in chemical resistance and excellent fluidity. In particular, it is an object of the present invention to provide a method for producing a transparent resin having less residual impurities, good chemical resistance and excellent processability and fluidity during bulk polymerization.

The above and other objects of the present invention can be achieved by the present invention described below.

The present invention to achieve the above object,

In the method for producing a transparent resin, a transparent resin characterized in that the polymerization of the reaction medium, styrene monomer, methyl methacrylate monomer and acrylonitrile monomer by the addition of an organic peroxide initiator having a bifunctional group as an initiator to bulk polymerization. It provides a method of manufacturing.

The organic peroxide initiator having the bifunctional group includes 1,1-bis (t-butyl peroxy) -3,3,5-trimethyl cyclohexane, 1,1-bis (t-butyl peroxy) cyclohexane and 1, It may be one or more selected from the group consisting of 1-bis (t-butyl peroxy) 2-methyl cyclohexane.

The present invention also provides a reaction mixture comprising a) 10 to 17% by weight of styrene monomer, 49 to 59% by weight of methyl methacrylate monomer, 3 to 15% by weight of acrylonitrile monomer and 25 to 35% by weight of reaction medium. Manufacturing step; b) adding 0.005 to 0.05 parts by weight of an organic peroxide initiator having a bifunctional group to the reaction mixture of step a) with respect to 100 parts by weight of the reaction mixture; And c) bulk polymerization of the mixture of step b) to provide a method for producing a transparent resin.

The bulk polymerization of step c) may be performed by performing polymerization at a temperature of 110 to 140 ° C. for 2 to 4 hours, and then further performing polymerization at a temperature of 120 to 160 ° C. for 2 to 4 hours.

The styrene monomer may be at least one selected from the group consisting of styrene, α-methylstyrene, p-bromostyrene, p-methylstyrene, p-chlorostyrene, and o-bromostyrene.

The reaction medium may be at least one selected from the group consisting of ethylbenzene, toluene and xylene.

In another aspect, the present invention provides a transparent resin characterized in that the Haze of the transparent resin produced by the above method is 1 or less and the melt constant is 20 or more.

Hereinafter, the present invention will be described in detail.

The styrene monomer is composed of styrene, α-methylstyrene, and derivatives having one or more addition substituents in the benzene nucleus (p-bromostyrene, p-methylstyrene, p-chlorostyrene, o-bromostyrene). It is preferable to select at least 1 type from the group.

The styrene-based monomer is preferably added 10 to 17% by weight, if less than 10% by weight is high in the viscosity of the reactants, there is a problem of poor processability and fluidity of the produced product, in excess of 17% by weight When added, there is a problem that the refractive index goes up and the transparency falls.

The reaction medium may be at least one selected from the group consisting of ethylbenzene, toluene, and xylene, preferably ethylbenzene. The content of the reaction medium is preferably 25 to 35% by weight, and when the content exceeds 35% by weight, the molecular weight is lowered and the yield is lowered, and when added to less than 25% by weight, the viscosity of the reactant is rapidly increased. There is an increasing problem.

The content of the methyl methacrylate used in the present invention is preferably in the range of 49 to 59% by weight, and when the content is more than 59% by weight, the viscosity of the reactant is rapidly increased, and is added at less than 49% by weight. In this case, there is a problem in that the refractive index increases and the Haze increases.

The content of the acrylonitrile monomer used in the present invention is preferably 3 to 15% by weight, and when the content is more than 15% by weight, thermal discoloration occurs well, and when added to less than 3% by weight, There is a problem of poor chemical properties.

The organic peroxide initiator is 1,1-bis (t-butyl peroxy) -3,3,5-trimethyl cyclohexane, and 1,1-bis (t-butyl peroxy) cyclohexane, 1,1- It is preferable to select at least one from the group consisting of bis (t-butyl peroxy) 2-methyl cyclohexane.

The content of the organic peroxide initiator is preferably added in an amount of 0.005 to 0.05 parts by weight based on 100 parts by weight of the reaction mixture consisting of styrene monomer, methyl methacrylate monomer, acrylonitrile monomer and the reaction medium, and exceeds 0.05 parts by weight. There is a problem in that the polymerization reaction occurs suddenly to increase the viscosity of the reactant rapidly, and when added to less than 0.005 parts by weight, there is a problem that the production yield is low and the heat discoloration occurs more due to the difference in the composition ratio in the polymer.

In the present invention, an organic peroxide initiator is added to a reaction mixture in which a styrene monomer, a methyl methacrylate monomer, an acrylonitrile monomer, and a reaction medium are mixed, and then subjected to a bulk polymerization at a temperature of 110 to 140 ° C. for 2 to 4 hours. Further, the bulk polymerization is further performed at a temperature of 120 to 160 ° C. for 2 to 4 hours to prepare a transparent resin having excellent chemical resistance and excellent fluidity.

The transparent resin produced through the present invention has a haze of 1 or less, a refractive index of 1.515 to 1.517, a melt constant of 20 to 25 under a load of 220 ° C. and 10 kg, and has excellent chemical resistance.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the examples.

Comparative Example 1

In a 1 L batch reactor, 12.825% by weight of styrene monomer, 58.425% by weight of methyl methacrylate, and 3.75% by weight of acrylonitrile were mixed with 25% by weight of ethylbenzene as a reaction medium, and the reaction mass was massed at a temperature of 110 ° C for 2 hours. The polymerization was carried out and further bulk polymerization at a temperature of 140 ° C. for 2 hours to prepare a transparent resin.

Example 1

Comparative Example except that 1,1-bis (t-butyl peroxy) -3,3,5-trimethyl cyclohexane, an organic peroxide having a bifunctional group as an initiator, was added at 0.005 parts by weight based on 100 parts by weight of the reaction mixture. A styrene resin was prepared in the same manner as in 1.

Example 2

In a 1 L batch reactor, 12.15% by weight of styrene monomer, 55.35% by weight of methyl methacrylate, and 7.5% by weight of acrylonitrile were mixed with 25% by weight of ethylbenzene as a reaction medium, and an organic peroxide of 1,1-bis (t-butyl). Peroxy) -3,3,5-trimethyl cyclohexane was added at 0.005 parts by weight based on 100 parts by weight of the reaction mixture, and then the reaction mass was bulk polymerized at a temperature of 110 ° C. for 2 hours and again at a temperature of 140 ° C. It was further mass polymerization during the time to prepare a transparent resin.

Comparative Example 2

Into a 1 L batch reactor, 11.475% by weight of styrene monomer, 52.275% by weight of methyl methacrylate, and 11.25% by weight of acrylonitrile were mixed with 25% by weight of ethylbenzene as a reaction medium, and the reaction mass was massed at a temperature of 110 ° C for 2 hours. The polymerization was carried out and further bulk polymerization for 2 hours at a temperature of 140 ° C. to prepare a transparent resin.

Comparative Example 3

In a 1 L batch reactor, 17.55% by weight of styrene monomer, 49.95% by weight of methyl methacrylate, and 7.5% by weight of acrylonitrile were mixed with 25% by weight of ethylbenzene as a reaction medium, and an organic peroxide of 1,1-bis (t-butyl). Peroxy) -3,3,5-trimethyl cyclohexane was added at 0.005 parts by weight based on 100 parts by weight of the reaction mixture, and then the reaction mass was bulk polymerized at a temperature of 110 ° C. for 2 hours and again at a temperature of 140 ° C. It was further mass polymerization during the time to prepare a transparent resin.

Example 3

Into a 1 L batch reactor, 11.475% by weight of styrene monomer, 52.275% by weight of methyl methacrylate, and 11.25% by weight of acrylonitrile were mixed with 25% by weight of ethylbenzene as a reaction medium, and an organic peroxide of 1,1-bis (t-butyl). Peroxy) -3,3,5-trimethyl cyclohexane was added at 0.005 parts by weight based on 100 parts by weight of the reaction mixture, and then the reaction mass was bulk polymerized at a temperature of 110 ° C. for 2 hours and again at a temperature of 140 ° C. It was further mass polymerization during the time to prepare a transparent resin.

Example 4

Into a 1 L batch reactor, 10.8% by weight of styrene monomer, 49.2% by weight of methyl methacrylate, and 15% by weight of acrylonitrile were mixed with 25% by weight of ethylbenzene as a reaction medium, and an organic peroxide of 1,1-bis (t-butyl). Peroxy) -3,3,5-trimethyl cyclohexane was added at 0.005 parts by weight based on 100 parts by weight of the reaction mixture, and then the reaction mass was bulk polymerized at a temperature of 110 ° C. for 2 hours and again at a temperature of 140 ° C. It was further mass polymerization during the time to prepare a transparent resin.

Experimental Example

The physical properties of the transparent resins prepared by the methods of Examples and Comparative Examples were measured, and the results are shown in Table 1 below. The measurement of chemical resistance used the following method.

Test of chemical resistance

After fixing a 3.2 mm thick bar manufactured by injection molding to a jig (R: 226.97 mm) at both ends, soybean oil was immersed in a gauze, and the center of the specimen was After placing it on, the specimen was allowed to soak in oil and left for 24 hours. After 24 hours, the surface appearance and cracks of the specimen were visually checked and the thickness change was measured and compared.

(◎: no change, ○: color change, △: cracks occur / surface change is severe, ×: not available)

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Number average molecular weight (Mn) 44,720 47,005 45,537 45,567 55,620 55,408 44.405 Weight average molecular weight (Mw) 112,246 123,152 132,512 141,258 122,921 138,521 126,554 Molecular Weight Distribution (PDI) 2.51 2.62 2.91 3.1 2.21 2.5 2.85 Haze 0.9 0.9 0.9 One 1.3 1.5 1.3 Refractive index 1.5157 1.5162 1.5165 1.5166 1.5163 1.5169 1.5189 Chemical resistance Visual check ○ ◎ ◎ ◎ △ ○ △ Thickness change (mm) 0.6 0.4 0.3 0.24 1.1 0.6 0.5 Tensile Strength Reduction Rate 37 24 22 22 65 41 32 Melt Constant (MI) 24 22 21 20 19 19 23

As can be seen in Table 1, the transparent resins of Examples 1 to 4 prepared by the production method of the present invention has a haze of 1 or less, a refractive index of 1.515 to 1.517 and a melt constant of 20 to 25 at a load of 220 ° C. and 10 kg. It turned out that it was excellent in chemical-resistance compared with the comparative examples 1-2 by the conventional method.

As described above, the method for producing a transparent resin according to the present invention is a useful invention having the effect of providing a method for producing a transparent resin excellent in chemical resistance and fluidity.

While the invention has been described in detail above with reference to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope and spirit of the invention, and such modifications and variations fall within the scope of the appended claims. It is also natural.

Claims (8)

In the manufacturing method of the transparent resin, A method for producing a transparent resin, characterized in that the polymerization is carried out by adding an organic peroxide initiator having a bifunctional group as an initiator to a mixture of a reaction medium, a styrene monomer, a methyl methacrylate monomer and an acrylonitrile monomer. The method of claim 1, The organic peroxide initiator having the bifunctional group includes 1,1-bis (t-butyl peroxy) -3,3,5-trimethyl cyclohexane, 1,1-bis (t-butyl peroxy) cyclohexane and 1, A method for producing a transparent resin, characterized in that at least one member selected from the group consisting of 1-bis (t-butyl peroxy) 2-methyl cyclohexane. The method of claim 1, a) preparing a reaction mixture by mixing 10 to 17% by weight of styrene monomer, 49 to 59% by weight of methyl methacrylate monomer, 3 to 15% by weight of acrylonitrile monomer and 25 to 35% by weight of reaction medium; b) adding 0.005 to 0.05 parts by weight of an organic peroxide initiator having a bifunctional group to the reaction mixture of step a) with respect to 100 parts by weight of the reaction mixture; And c) bulk polymerizing the mixture of step b) Method for producing a transparent resin, characterized in that comprises a. The method of claim 3, wherein The bulk polymerization of step c) After performing the polymerization for 2 to 4 hours at a temperature of 110 to 140 ℃, the method of producing a transparent resin, characterized in that the polymerization is carried out for a further 2 to 4 hours at a temperature of 120 to 160 ℃. The method of claim 1, The styrene monomer is at least one member selected from the group consisting of styrene, α-methylstyrene, p-bromostyrene, p-methylstyrene, p-chlorostyrene and o-bromostyrene. Way. The method of claim 1, And the reaction medium is at least one selected from the group consisting of ethylbenzene, toluene and xylene. A transparent resin produced by the method according to any one of claims 1 to 6. The method of claim 7, wherein Haze (Haze) of the transparent resin is transparent resin, characterized in that the melt constant is 20 or more.