KR100788590B1 - Production method for monovinylaromatic polymer with improved environmental stress crack resistance - Google Patents

Abstract

 The present invention relates to a method for producing a rubber-modified styrene resin having excellent environmental stress crack resistance (ESCR), and more particularly to the impact-resistant styrene resin containing butadiene rubber polymer and styrene monomer. In the preparation, the present invention relates to a rubber-modified styrenic resin manufacturing method characterized in that the polybutene, high-viscosity polyorganosiloxane and mineral oil are added and graft copolymerized during the polymerization process. It is excellent in processability, recyclable, and particularly excellent in rigidity and vacuum formability, thereby providing a rubber-modified styrene resin useful for the manufacture of sheet molded articles of thin films.

Rubber modified styrene resin, bulk polymerization, environmental crack resistance

Description

PROCESSION METHOD FOR MONOVINYLAROMATIC POLYMER WITH IMPROVED ENVIRONMENTAL STRESS CRACK RESISTANCE

The present invention relates to a method for producing a rubber-modified styrene resin having excellent environmental stress crack resistance (ESCR), and more particularly to the impact-resistant styrene resin containing butadiene rubber polymer and styrene monomer. In the production, the present invention relates to a method for producing a rubber-modified styrene resin in which polybutene, high-viscosity polyorganosiloxane and mineral oil are added and graft copolymerized to improve environmental cracking resistance during polymerization.

Rubber modified styrene resin is a thermoplastic resin obtained by graft copolymerization of styrene monomers in the presence of rubber polymers, which is one of the disadvantages of styrene resins. Extruded sheets have been used in various fields requiring impact resistance, but their use in various applications has been limited due to low environmental crack resistance.

Environmental cracking resistance is particularly known as one of the most important properties for thermoplastic resins used in food containers and refrigerator interior materials, and the production technology of rubber modified styrene resin having excellent environmental cracking resistance has been studied. In addition, resins having excellent environmental crack resistance have recently been increasingly used in the form of thin film molding according to the characteristics of the market as the molded products are gradually enlarged and highly functionalized.

To meet these demands, resin manufacturing methods that have been excellent in environmental cracking resistance until now do not balance the requirements for stiffness, impact resistance, environmental cracking resistance and vacuum forming, so that when the resin has excellent rigidity, There is a decrease in environmental cracking.

Therefore, in order to solve this problem, the rubber polymer content and particle size are maintained and manufactured using various additives during the polymerization process to increase environmental crack resistance, and the result is not generally satisfactory.

US Pat. No. 5,543,461 discloses a method for improving environmental cracking resistance by adding 1 to 4 parts by weight of polybutene having a number average molecular weight of 900 to 2,000 in a rubber-modified styrene resin, and US Pat. No. 5,861,455 describes mineral oil and A method of improving environmental cracking resistance by introducing polyisobutylene into 0.5 to 3 parts by weight of rubber modified styrene resin, respectively, is disclosed. In addition, US Pat. No. 6,613,837 discloses a method for improving environmental cracking resistance by adding 1 to 4 parts by weight of polyisobutylene having a viscosity of 196 to 233 cst at 99 ° C. in a rubber-modified styrene resin.

However, all of the above patents do not achieve satisfactory levels of environmental cracking resistance.

In order to solve the problems of the prior art as described above, an object of the present invention is to provide a method for producing a rubber-modified styrene resin having excellent environmental cracking resistance while maintaining properties such as impact resistance and rigidity.

In order to achieve the above object, the present invention is a method for producing a rubber-modified styrene resin,

A first step of preparing a mixed solution containing a butadiene rubber polymer, a styrene monomer and a polymerization solvent;

A second step of adding and mixing a molecular weight regulator, polybutene and high viscosity polyorganosiloxane to the mixed solution of the first step;

The mixed solution of the second stage is introduced into a first reactor of a continuous polymerization apparatus in which two or more stirring reactors are connected in series at a reactor temperature of 100 to 180 ° C. to perform graft polymerization, and then continuously introduced into a second reactor to provide final air. A third step of polymerizing the coalescence;

A fourth step of introducing a mineral oil after the devolatilization process of the final copolymer of the third step; And

A fifth step of pelletizing the final copolymer of the fourth step;

It provides a method for producing a rubber-modified styrene-based resin comprising a.

The present invention presents an optimal condition for the type, content, and combination of additives such as molecular weight modifier, polybutene, high viscosity polyorganosiloxane, and mineral oil in butadiene-based rubber polymer and styrene-based monomer, and the additives have a synergistic effect. It is a method for producing a rubber-modified styrene resin is configured to achieve improved environmental cracking resistance and excellent rigidity.

Hereinafter, the present invention will be described in detail.

In the first step of the present invention, a mixed solution containing a butadiene rubber polymer, a styrene monomer and a polymerization solvent is prepared.

The butadiene-based rubber polymer is a polybutadiene prepared using butadiene, is dissolved in the styrene monomer and the polymerization solvent and introduced into the reactor to be dispersed on the styrene resin.

The butadiene rubber polymer may have a viscosity of 5% styrene solution at 25 ° C. of 100 to 300 cps. If the viscosity is less than 100 cp or more than 300 cp, there is a problem that the environmental cracking resistance and stiffness are not balanced.

The butadiene-based rubber polymer is preferably used in 3 to 10 parts by weight based on 100 parts by weight of the mixed solution of the first step consisting of butadiene-based rubber polymer, styrene monomer and a polymerization solvent. When the content is less than 3 parts by weight, the impact resistance of the produced resin is significantly lowered. If the content is more than 10 parts by weight, the environmental cracking resistance is advantageous, but the rigidity is lowered there is an undesirable problem.

The styrene monomers include alkyl styrene and o-bromo styrene such as styrene, α-methyl styrene, o-methyl styrene, p-methyl styrene, m-methyl styrene, ethyl styrene, i-butyl styrene and t-butyl styrene. at least one selected from the group consisting of halogenated styrenes such as p-bromo styrene, m-bromo styrene, o-chloro styrene, p-chloro styrene, and m-chloro styrene, and styrene is preferable. Do.

It may further comprise a vinyl monomer copolymerizable with the styrene monomer.

The vinyl monomer copolymerizable with the styrene monomer and the styrene monomer is preferably used in an amount of 60 to 97 parts by weight based on 100 parts by weight of the mixed solution of the first step.

The polymerization solvent may be selected from one or more selected from the group consisting of benzene, toluene, ethylbenzene and xylene, and ethylbenzene is preferable.

The polymerization solvent is preferably used in an amount of 0 to 30 parts by weight based on 100 parts by weight of the mixed solution of the first step.

In the second step of the present invention, a molecular weight modifier, polybutene and high viscosity polyorganosiloxane are added to the mixed solution of the first step and mixed.

The molecular weight modifier may be used by selecting one or more from the group consisting of n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan and α-methyl styrene dimer, and n-octyl mercaptan or t- Dodecyl mercaptan is preferred.

The molecular weight modifier is preferably used in 0.005 to 0.2 parts by weight, more preferably 0.01 to 0.1 parts by weight based on 100 parts by weight of the mixed solution of the first step.

It is preferable that the polybutene has a low molecular weight polybutene, in particular, a number average molecular weight of about 500 to 3,000. If the number average molecular weight is less than 500 or more than 3,000, there is a problem that can not balance the environmental crack resistance and rigidity.

The polybutene is preferably used in an amount of 0.01 to 2.0 parts by weight, more preferably 0.05 to 1.0 part by weight, based on 100 parts by weight of the mixed solution of the first step.

The high viscosity polyorganosiloxane has a structure as shown in the following formula (1).

[Formula 1]

In the high viscosity polyorganosiloxane, R ₁ to R ₄ in Formula 1 may each independently represent a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an alkyl group such as isopropyl, an alicyclic hydrocarbon group such as a cyclohexyl group, a phenyl group, An aromatic group such as a benzyl group or a substituent containing a hydroxyl group, an alkoxy group, an amino group, an amide group, an epoxy group, a carboxyl group, a halogen group, an ester group, and the like may be used, and an alicyclic hydrocarbon group is preferable.

The high viscosity polyorganosiloxane preferably has a viscosity in the range of about 5,000 to 20,000 cst, more preferably about 8,000 to 15,000 cst. If the viscosity is less than 5,000 cst can not be expected to improve the ESCR properties, if it exceeds 20,000 cst there is a problem that the dispersibility in the polymer is lowered, mechanical properties and the effect of improving the ESCR properties is drastically reduced.

The high viscosity polyorganosiloxane is preferably used in an amount of 0.01 to 2.0 parts by weight, more preferably 0.05 to 1.0 parts by weight, based on 100 parts by weight of the mixed solution of the first step.

In the third step of the present invention, the mixture solution of the second step is introduced into the first reactor of the continuous polymerization apparatus in which two or more stirring reactors are connected in series at a reactor temperature of 100 to 180 ℃ to perform graft polymerization, and then the second Continuous injection into the reactor polymerizes the final copolymer.

In the production method of the rubber-modified styrenic resin, a polymerization initiator, a plasticizer, an antioxidant, or an ultraviolet absorber used in conventional polymer polymerization may be used.

The polymerization initiator may be peroxy ketals such as 1,1-bis (t-butyl peroxy) -3,3,5-trimethyl cyclohexane, di-t-butyl peroxide, 2,5-dimethyl-2, Dialkyl peroxides such as 5-di (t-butyl peroxy) hexane, diacyl peroxides such as dibenzoyl peroxide, peroxy esters such as t-butyl peroxy isopropyl carbonate, and cyclohexanone One or more types can be selected and used from the group which consists of kenon peroxides, such as a peroxide, and azo compounds, such as 2,2'- azobisisobutylonitrile, and an organic peroxide type polymerization initiator is preferable.

In the production method of the rubber-modified styrenic resin, the graft polymerization is capable of producing a continuous or batch bulk polymerization, a solution polymerization and a bulk-suspension polymerization, there is no problem of productivity and quality uniformity and water pollution. Continuous bulk polymerization or solution polymerization is preferred.

In the fourth step of the present invention, mineral oil is added after devolatilizing the final copolymer of the third step.

Preferably, the mineral oil has a weight average molecular weight of about 500 to 2,000.

The mineral oil is preferably used in an amount of 0.01 to 2.0 parts by weight, more preferably 0.05 to 1.0 part by weight, based on 100 parts by weight of the mixed solution of the first step.

In the fifth step of the present invention, the final copolymer of the fourth step is pelletized.

The impact resistant rubber-modified styrene resin produced through the above production method has excellent environmental cracking resistance when the average particle diameter of the rubber particles in the resin is 5.0 μm or more. In addition, in consideration of environmental cracking resistance and rigidity, it is preferable that the average particle diameter of the rubber particles in the resin is 6.0 to 10.0 ㎛.

The rubber-modified styrene-based resin has an average molecular weight of 190,000 or more in consideration of environmental cracking resistance and rigidity.

The rubber-modified styrene resin is an optimum for the type, content and combination of additives such as molecular weight regulators, polybutene, high viscosity polyorganosiloxane and mineral oil in the resin manufacturing process using a mixed solution of butadiene rubber polymer and styrene monomer A rubber-modified styrene-based resin is added under conditions of to improve environmental cracking resistance.

The rubber-modified styrene-based resin has excellent environmental cracking resistance, impact resistance and extrusion processability, recyclability, and in particular, it is excellent in stiffness and vacuum formability, thereby making it possible to manufacture thin sheet molded articles using the same. It is applied at the time of manufacture of modified styrene resin.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

EXAMPLE

Example 1

Butadiene rubber polymer (25 degreeC, 5% styrene solution viscosity 250cps) 7.2 weight part, styrene 79.0 weight part, and ethylbenzene 13.8 weight part were used as the composition of the raw material mixture solution. 0.1 parts by weight of polybutene having a viscosity of 210 cst at 100 ° C. and a number average molecular weight of 950, 100 parts by weight of the mixed solution, 0.07 parts by weight of high viscosity polydimethylsiloxane having a viscosity of 10,000 cst at 25 ° C., and t-dodecyl mercaptan 0.01 part by weight was added.

The mixed solution was introduced into a continuous polymerization apparatus in which four stirred reactors were connected in series to perform polymerization continuously. The temperature at the inlet of the polymerization apparatus was 135 ° C and the temperature at the outlet was 155 ° C.

The final polymerization mixture solution was sent to a devolatilization reactor, and the unreacted monomer and polymerization solvent were removed at 230 ° C. and 20 torr. Then, 0.05 parts by weight of mineral oil having a viscosity of 120 cst at 30 ° C. was added thereto, followed by pelletization to form a final rubber. Modified styrene resin was obtained.

Example 2

Except for using 0.03 parts by weight of polybutene in the second step of Example 1 was carried out in the same composition and method as in Example 1.

Example 3

Except for using 0.03 parts by weight of high viscosity polydimethylsiloxane in the second step of Example 1 was carried out in the same composition and method as in Example 1.

Example 4

Except for using a mineral oil 0.03 parts by weight after the devolatilization process in the fourth step of Example 1 was carried out in the same composition and method as in Example 1.

Example 5

Except for using 0.03 parts by weight of polybutene in the second step of Example 1, and 0.03 parts by weight of mineral oil after the devolatilization process in the fourth step was carried out in the same composition and method as in Example 1.

Example 6

Except for using 0.12 parts by weight of high viscosity polydimethylsiloxane in the second step of Example 1 was carried out in the same composition and method as in Example 1.

Example 7

Except for using 0.15 parts by weight of polybutene in the second step of Example 1, and 0.075 parts by weight of mineral oil after the devolatilization process in the fourth step was carried out in the same composition and method as in Example 1.

Comparative Example 1

Except for using the polybutene, high viscosity polydimethylsiloxane and mineral oil in Example 1 was carried out in the same composition and method as in Example 1.

Comparative Example 2

Except that the high viscosity polydimethylsiloxane was not used in the second step of Example 1 was carried out in the same composition and method as in Example 1.

Comparative Example 3

Except not using a high viscosity polydimethylsiloxane in the second step of Example 1, 0.1 parts by weight of mineral oil after the devolatilization process in the fourth step was carried out in the same composition and method as in Example 1.

Comparative Example 4

A second step of Example 1 was carried out in the same composition and method as in Example 1 except that 0.07 parts by weight of a low viscosity polydimethylsiloxane having a viscosity of 1,000 cst at 25 ° C.

Comparative Example 5

Except for using 0.12 parts by weight of low viscosity polydimethylsiloxane in the second step of Example 1 was carried out in the same composition and method as in Example 1.

Comparative Example 6

Except for using 0.12 parts by weight of low viscosity polydimethylsiloxane in the second step of Example 1, and 0.1 parts by weight of mineral oil after the devolatilization process in the fourth step was carried out in the same composition and method as in Example 1.

Injection molding of the resin prepared according to the Examples and Comparative Examples to measure the physical properties by the following method and the results are shown in Table 1 below.

* Tensile strength and elongation-It was measured by ASTM D638 method.

* ESCR property-Cyclopentane solution is added to airtight container at room temperature to create cyclopentane gaseous atmosphere, and the tensile strength test specimen is immersed in 0.7% Stress Jig for 1 hour in the airtight container and then measured for tensile strength and elongation. It was.

* Izod Impact-measured by ASTM D256 method.

division input  Physical property and ESCR test result Polybutene Polydimethylsiloxane Mineral oil TS TE TS retention rate after ESCR test (%) TE retention after ESCR test (%) Impact Strength (1/4 ") 10,000 cst 1,000 cst Example 1 0.1 0.07 0 0.05 311 114 94.2 62.1 9.2 Example 2 0.03 0.07 0 0.05 299 105 90.6 56.3 9.2 Example 3 0.1 0.03 0 0.05 304 112 79.3 51.2 9.2 Example 4 0.1 0.07 0 0.03 314 108 92.4 55.7 9.0 Example 5 0.03 0.07 0 0.03 298 101 88.7 53.3 9.0 Example 6 0.1 0.12 0 0.05 309 114 94.3 63.3 9.2 Example 7 0.15 0.07 0 0.075 305 117 94.4 62.3 9.3 Comparative Example 1 0 0 0 0 284 83 58.0 35.7 8.8 Comparative Example 2 0.1 0 0 0.05 306 103 64.3 42.6 9.0 Comparative Example 3 0.1 0 0 0.1 302 107 67.5 43.2 9.1 Comparative Example 4 0.1 0 0.07 0.05 307 105 70.2 45.1 9.0 Comparative Example 5 0.1 0 0.12 0.05 305 105 72.4 47.3 9.0 Comparative Example 6 0.1 0 0.12 0.1 301 109 72.5 47.8 9.1

As described above, the method for preparing the rubber-modified styrene resin of the present invention is a type, content and combination of additives such as molecular weight regulator, polybutene, high viscosity polyorganosiloxane and mineral oil in butadiene rubber polymer and styrene monomer. By presenting the optimum conditions for the additives are synergistic effect of each other by excellent environmental cracking resistance, impact resistance and extrusion processability, recycling is possible, in particular stiffness and vacuum formability excellent sheet molding of thin film There is an effect of providing a rubber-modified styrene resin useful in the production.

Although described in detail above with reference to the described embodiments of the present invention, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention, and such variations and modifications belong to the appended claims. It is also natural.

Claims (10)

In the manufacturing method of the rubber modified styrene resin, A first step of preparing a mixed solution containing a butadiene rubber polymer, a styrene monomer and a polymerization solvent; A second step of adding and mixing a molecular weight regulator, polybutene, and high viscosity polyorganosiloxane to the mixed solution of the first step; The mixed solution of the second stage is introduced into a first reactor of a continuous polymerization apparatus in which two or more stirring reactors are connected in series at a reactor temperature of 100 to 180 ° C. to perform graft polymerization, and then continuously introduced into a second reactor to provide final air. A third step of polymerizing the coalescence; A fourth step of introducing a mineral oil after the devolatilization process of the final copolymer of the third step; And A fifth step of pelletizing the final copolymer of the fourth step Method of producing a rubber-modified styrene resin, characterized in that comprises a. The method of claim 1, The butadiene-based rubber polymer is used in that the viscosity of the 5% styrene solution of 100 to 300 cp at 25 ℃, 3 to 10 parts by weight based on 100 parts by weight of the mixed solution of the first step Method for producing styrene resin. The method of claim 1, The styrene monomers are styrene, α-methyl styrene, o-methyl styrene, p-methyl styrene, m-methyl styrene, ethyl styrene, i-butyl styrene, t-butyl styrene, o-bromo styrene, p-bromo Styrene, m-bromo styrene, o-chloro styrene, p-chloro styrene and m- chloro styrene selected from the group consisting of one or more of 60, 100 parts by weight of the mixed solution of the first step To 97 parts by weight of the rubber-modified styrenic resin production method characterized in that it is used. The method of claim 1, The polymerization solvent is used by selecting one or more from the group consisting of benzene, ethyl benzene, toluene and xylene, but is used in a rubber modified 0 to 30 parts by weight based on 100 parts by weight of the mixed solution of the first step Method for producing styrene resin. The method of claim 1, The molecular weight modifier may be selected from the group consisting of n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan and α-methyl styrene dimer, and is used at 100 weight of the mixed solution of the first step. A method for producing a rubber-modified styrene resin, characterized in that it is used in 0.005 to 0.2 parts by weight relative to the part. The method of claim 1, The polybutene may be a low molecular weight polybutene having a number average molecular weight of 500 to 3,000, but is used in an amount of 0.01 to 2.0 parts by weight based on 100 parts by weight of the mixed solution of the first step. Manufacturing method. The method of claim 1, The high viscosity polyorganosiloxane is represented by the following formula (1), the viscosity is used 5,000 to 20,000 cst, characterized in that the rubber using a 0.01 to 2.0 parts by weight based on 100 parts by weight of the mixed solution of the first step Method for producing modified styrene resin. [Formula 1]

In Formula 1, R ₁ to R ₄ are a hydrogen atom, an alkyl group such as methyl group, ethyl group, n-propyl group, isopropyl, alicyclic hydrocarbon group such as cyclohexyl group, aromatic group such as phenyl group, benzyl group, or the substituent To a hydroxyl group, an alkoxy group, an amino group, an amide group, an epoxy group, a carboxyl group, a halogen group, an ester group, and the like. The method of claim 1, The mineral oil is used in the weight average molecular weight of 500 to 2,000, the method of producing a rubber-modified styrene resin, characterized in that used in 0.01 to 2.0 parts by weight based on 100 parts by weight of the mixed solution of the first step. The method of claim 1, The graft polymerization step of the third step is a method for producing a rubber-modified styrene resin, characterized in that selected from the group consisting of continuous or batch bulk polymerization, solution polymerization, and block-suspension polymerization. The method of claim 1, The rubber-modified styrene resin is a rubber-modified styrene resin, characterized in that the average particle diameter of the rubber particles in the resin is 5.0 ㎛ or more, the weight average molecular weight is 190,000 or more.