KR100612081B1 - Method for preparating rubber-modified polystylenic resins having high impact resistance and high gloss - Google Patents

Abstract

The present invention comprises the steps of a) preparing a rubber mixed solution comprising a rubber polymer, a styrene-based vinyl monomer and a solvent, b) injecting a low temperature initiator into the rubber mixed solution, c) the reaction solution produced in step b) It provides a method of producing a rubber-modified styrene resin comprising the step of polymerizing a monomer in the step, and d) separating the unreacted monomer and the solvent from the reaction solution of step c) and the rubber-modified styrene resin produced thereby do. The rubber-modified styrene resin produced by the present invention is excellent in glossiness and impact resistance.

Rubber modified styrene resin, low temperature initiator, impact resistance, glossiness

Description

METHODS FOR PREPARATING RUBBER-MODIFIED POLYSTYLENIC RESINS HAVING HIGH IMPACT RESISTANCE AND HIGH GLOSS

The present invention relates to a method for producing a rubber-modified styrene resin having excellent gloss and impact resistance.

Conventionally, in order to improve the gloss and impact resistance of the styrene resin composition at the same time, the rubber polymer is dispersed in the styrene resin by blending a rubber polymer into the styrene resin or polymerizing the styrene monomer in the presence of the rubber polymer. A modified styrene resin composition was prepared and used as a material for the production of electric and electronic parts, sheets and the like.

In the rubber-modified styrene resin composition, it is known that the size and distribution of the particles of the rubbery polymer dispersed in the styrene-based polymer in a particle form have a close relationship with physical properties such as glossiness, stiffness and impact strength. That is, the smaller the particle size of the rubbery polymer is, the more excellent the rigidity and gloss are, but the impact resistance is lowered, thereby substantially eliminating the effect of improving the impact resistance.

In order to solve the above problems, Japanese Patent Publication No. 48-185945 and Japanese Patent Publication No. 64-74209 use a styrene-butadiene block copolymer having a high styrene content as a rubber component in the production of styrene resins. Polymerization produces known rubber particles having a core-shell structure of not more than 0.5 μm [Angew. Macromol. Chem. 58/59, p. 157-158 (1977), which describes a method for producing an impact resistant styrene resin having excellent gloss and transparency of moldings. However, these methods do not significantly improve the surface gloss of the moldings, and there are also disadvantages in manufacturing raw material costs.

In addition, U.S. Patent No. 4,493,922 and Japanese Patent Publication No. 63-112646 combine the styrene resin with a conventional impact resistant styrene resin containing a small amount of rubber particles of a cell structure to maintain a high level of gloss of a molded article. While improving the impact resistance is described. However, in these methods, the impact resistance is greatly improved, but the gloss is lowered, so it is necessary to add polydimethylsiloxane to the resin, and the resins are separately mixed in an extruder or the polymerization liquid of the small particle rubber and the large particle rubber is polymerized during the polymerization reaction. It must be prepared by mixing. Therefore, these manufacturing methods have a disadvantage in that it is difficult to establish the process operating conditions and the manufacturing cost increases.

U. S. Patent No. 6,350, 813 describes a process for producing high gloss, high impact styrene resins using branched polybutadiene and linear polybutadiene instead of styrene-butadiene block copolymers as a method for reducing the cost of the raw materials of manufacture. However, this method also has the disadvantage that the gloss is not sufficiently improved. In addition, Korean Patent Publication No. 1999-0075609 discloses a method for producing a styrene resin that dramatically improves gloss and impact by using a mixture of styrene-butadiene block copolymers and linear polybutadiene, but still has a raw material cost. The disadvantage is high.

The present inventors added a low-temperature initiator as a polymerization initiator as a polymerization initiator to a rubber mixed solution in a method of producing a rubber-modified styrene-based resin to polymerize a part of monomers at a low temperature, thereby dispersing the rubber in the final rubber-modified styrene-based resin. It has been found that some of the particles can be reduced in size. Accordingly, an object of the present invention is to provide a method for producing a rubber modified styrene resin having excellent gloss and impact resistance using a low temperature initiator and a rubber modified styrene resin produced thereby.

The present invention is a method for producing a rubber modified styrene resin,

a) preparing a rubber mixed solution comprising a rubber polymer, a styrenic vinyl monomer and a solvent,

b) injecting a low temperature initiator into the rubber mixed solution,

c) polymerizing the monomer in the reaction solution produced in step b), and

d) separating the unreacted monomer and the solvent from the reaction solution of step c)

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

The present invention also provides a rubber-modified styrene resin produced by the method of the present invention.

Hereinafter, the present invention will be described in detail.

In the method for producing a rubber-modified styrene resin of the present invention, the first step is to prepare a rubber mixed solution containing a rubber polymer, a styrene vinyl monomer and a solvent.

The first step may be accomplished by dissolving the rubber polymer in styrene vinyl monomers and a solvent. This step is preferably such that the rubber polymer is sufficiently dissolved in the vinyl monomer and solvent at about 60 ° C.

The rubber polymer that can be used in the present invention is not particularly limited as long as it is known in the art to be used in the production of styrene resin. However, in the present invention, it is preferable to use linear polybutadiene, branched polybutadiene or a mixture thereof as the rubber polymer. This is because linear polybutadiene or branched polybutadiene is not only inexpensive, but also low in viscosity, and thus may contribute to the reduction of the size of rubber particles dispersed in the styrene resin produced.

It is preferable that the linear polybutadiene has a viscosity of 5% styrene solution at 120 ° C. of 120 to 140 cps, and the branched polybutadiene has a viscosity of 30% to 40 cps of 5% styrene solution at 25 ° C. When using a mixture of linear polybutadiene and branched polybutadiene as the rubber polymer, they are preferably mixed in a weight ratio of 70/30 to 30/70.

In the method of the present invention, the amount of the rubber polymer used is preferably 5 to 20% by weight, preferably 6 to 12% by weight of the rubber mixed solution.

The rubber polymer is dispersed in the styrene resin produced by the method of the present invention in the form of particles, the particle diameter, particle size distribution and particle structure of the rubber polymer in the resin is agitated rotation speed, reaction temperature, reaction in the mixing and polymerization process It may be controlled by the viscosity of the reaction solution, the interfacial tension or the like by the time, the composition of the reaction solution, or the like.

The styrene-based vinyl monomer that can be used in the present invention is a group consisting of halogenated styrene and halogenated alkyl styrene, such as styrene, methyl styrene, ethyl styrene, alkyl styrene such as butyl styrene, chloro styrene, bromostyrene, fluorostyrene There is at least one monomer selected. Among these, styrene, alpha-methylstyrene, ortho-methylstyrene, meta-methylstyrene, para-methylstyrene, and the like are more preferable. In the method of this invention, it is preferable that the usage-amount of the said styrene-type vinyl monomer is 60 to 80 weight% of a rubber mixed solution.

The solvent usable in the present invention includes one or two or more mixed solvents selected from the group consisting of normal hexane, cyclohexane, toluene, ethylbenzene and benzene. In the method of this invention, it is preferable that the usage-amount of the said solvent is 5 to 35 weight% of a rubber mixed solution.

In the method of the present invention, the second step is a step of adding a low-temperature initiator to the rubber mixture solution prepared in the first step.

The low temperature initiator means an initiator whose half-life temperature is 70 ° C. or less. In the usual polymerization reaction, the monomers in the rubber mixed solution are mostly polymerized due to the high temperature. However, when the low temperature initiator is used, only a part of the monomers in the rubber mixed solution can be polymerized at a low temperature. In the present invention, by using a low-temperature initiator to polymerize a portion of the monomer in the rubber mixture solution at a low temperature, that is, 70 ℃ or less, it is possible to improve the graft ratio of styrene in a conventional polymerization reaction to be carried out, which is to improve the interfacial tension of the rubber particles As a result, it is possible to reduce the size of some of the rubber particles dispersed in the resulting styrene resin.

According to the above working principle, in the styrene resin according to the present invention, rubber particles having relatively large particles and small rubber particles are mixed to compensate for the gloss and impact resistance characteristics according to the particle size. It is possible to provide a rubber-modified styrene resin having excellent silver gloss and impact resistance.

The low temperature initiator that can be used in the present invention includes a low temperature initiator of a peroxyester series or a low temperature initiator of a peroxydicarbonate series. Specifically, peroxyester-based initiators such as 1,1-dimethyl-3-hydroxybutyl, alpha-cumyl, t-cumyl, t-butyl peroxy neodecanoate, diisopropyl and di-3-meth Low-temperature initiators of peroxydicarbonate series such as oxybutyl, di (2-ethylhexyl) and di-sec-butyl peroxydicarbonate. However, it is not limited only to these examples.

In the second step, it is preferable to add about 100 to 1000 ppm of the low temperature initiator to the rubber mixed solution and maintain the polymerization conversion rate of the monomers in the rubber mixed solution to 1 to 10% by maintaining the mixture for 2 to 4 hours.

In the method of the present invention, the third step is to polymerize the remaining unpolymerized monomers in the reaction solution produced in the second step. The polymerization reaction can be carried out by a conventional polymerization reaction method known in the art, and is not limited to a specific method. In the present invention, the polymerization reaction can be carried out, for example, by raising the temperature to 120 ° C or higher. In this polymerization step, the polymerization conversion rate of the monomers in the reaction solution is about 70-90%.

Preferably, the polymerization reaction step can be carried out continuously as follows.

The reaction solution produced in the second step is continuously supplied to the first reactor, and reacted under the condition that the reaction temperature is 120 to 145 ° C until the polymerization conversion rate of the monomer in the reaction solution becomes 10 to 40% by weight. At this time, the rubber particles in the resin produced are preferably made of 50 to 99% of the rubber particles having an average particle diameter of 0.1 to 0.5 µm and 1 to 50% of the rubber particles having an average particle diameter of 1 to 5 µm. Thus, by giving rubber particle | grains two types of particle size distribution, the glossiness, rigidity, and impact strength of resin according to a particle size can be compensated.

Subsequently, the reaction solution produced in the first reactor is continuously supplied to the second, third, and fourth reactors, and the polymerization reaction is carried out until the polymerization conversion rate of the monomer is 70 to 90% by weight.

In the polymerization step, additional auxiliary materials may be added if necessary.

In the method of the present invention, the fourth step is a step of separating the unreacted monomer and the solvent from the reaction solution subjected to the polymerization reaction. By passing through this step, a high gloss and high impact styrene resin can be produced. Specifically, in the fourth step, the reaction solution obtained in the third step may be continuously supplied to the devolatilization apparatus to separate the polymer including the rubber component from the unreacted monomer and the solvent.

Hereinafter, the present invention will be described in detail by way of Examples and Comparative Examples. However, an Example is for illustrating this invention and is not limited only to these.

Example

Molding and physical property evaluation used in the present invention were carried out based on the conditions described in the following (1), (2) and (3).

(1) Molding condition: 5 oz injection molding machine, molding temperature 210 ℃, mold temperature 60 ℃

(2) Izod impact strength: ASTM D-256, 1/4 ″ test piece

(3) Glossiness: JIS-K-7105, incident angle 45˚

Example 1

3.2 parts by weight of linear polybutadiene (5% styrene solution viscosity at 25 ° C 130 cps) (based on rubber mixed solution, below) 3.2 parts by weight of branched polybutadiene (5% styrene solution viscosity at 25 ° C 35 cps) 60 parts by weight A rubber mixed solution was prepared by completely dissolving 18 parts by weight of ethylbenzene and 75.6 parts by weight of styrene under the condition of ℃.

Under the same temperature condition, 100 ppm of t-amyl peroxy neodecanoate, a low-temperature initiator, was added to the rubber mixture solution, and polymerization was performed for 3 hours, and then a raw material rubber solution was prepared by prescribing an antioxidant.

The raw rubber solution was continuously fed at a rate of 12 L / H into four continuous stirred reactors connected in series having a volume of 26 L / 16 L / 16 L / 16 L. Each reactor temperature was 135 ℃, 140 ℃, 150 ℃, 155 ℃ in 1/2/3/4 order.

Subsequently, the reaction solution was continuously sent from the fourth reactor to the devolatilization apparatus to separate the unreacted monomer and solvent from the polymer solution at a high temperature of 240 ° C. and a reduced pressure of 10 Torr, and then discharged using a gear pump to pellet. A high gloss high impact rubber modified styrene resin in the form of) was obtained.

After the obtained resin was injected under the molding conditions described above, impact and gloss were measured. Detailed physical property measurement results are shown in Table 1.

Example 2

A rubber modified styrene resin was prepared in the same manner as in Example 1, except that 500 ppm of a low temperature initiator was added. Its impact and gloss were measured and the results are shown in Table 1 below.

Comparative example

A rubber modified styrene resin was prepared in the same manner as in Example 1 except that the low temperature initiator was not used. Its impact and gloss were measured and the results are shown in Table 1 below.

Low Temperature Initiator Content (ppm) % Conversion * Impact Strength (Kgcm / cm) Glossiness (45 °) Example 1 100 1.5 8.8 92 Example 2 500 6.1 10.2 98 Comparative example 0 0 8.9 91 * Conversion rate represents the polymerization conversion of the vinyl monomer base polymerization before the polymerization reaction in step c) according to the present invention, which means the polymerization conversion rate by the addition of a low temperature initiator.

As shown in Table 1, the resin of Example 1 to which the low temperature initiator was added 100 ppm showed the same impact strength and glossiness as the resin of the comparative example without the low temperature initiator, but the addition amount of the low temperature initiator was 500 ppm. The resin of Example 2, which was increased by, exhibited better impact strength and gloss than the resin of Comparative Example.

In the present invention, a resin product having improved gloss and impact resistance can be obtained by polymerizing a part of monomers by a low-temperature initiator before the usual polymerization reaction in the method for producing a rubber-modified styrene resin.

Claims (14)

a) preparing a rubber mixed solution comprising a rubber polymer, a styrenic vinyl monomer and a solvent; b) adding a low temperature initiator having a half-life temperature of 70 ° C. or less to the rubber mixed solution for 1 hour, and polymerizing the monomer in the rubber mixed solution to a polymerization conversion rate of 1 to 10 wt% at a temperature of 70 ° C. or less; c1) supplying the reaction solution produced in step b) to the first reactor and reacting the monomers under a reaction temperature of 120 to 145 ° C until the polymerization conversion rate of the monomers is 10 to 40% by weight; c2) continuously supplying the reaction solution produced in the first reactor to one or more reactors and reacting until the polymerization conversion rate of the monomer is 70 to 90% by weight; And d) separating the unreacted monomer and the solvent from the reaction solution of step c2); Method of producing a rubber-modified styrene resin comprising a. According to claim 1, wherein in the rubber mixture of step a) the rubber polymer is 5 to 20% by weight, the vinyl monomer is 60 to 80% by weight, the solvent is characterized in that it contains 5 to 35% by weight The manufacturing method of the rubber modified styrene resin to make. The method of claim 1, wherein the rubber polymer of step a) is selected from the group consisting of linear polybutadiene, branched polybutadiene, and mixtures thereof. According to claim 3, wherein the mixture of the linear polybutadiene and branched polybutadiene is a rubber-modified styrene resin, characterized in that the linear polybutadiene and branched polybutadiene is mixed in a weight ratio of 70/30 ~ 30/70 Way. The method of claim 1, wherein the styrenic vinyl monomer of step a) is at least one monomer selected from the group consisting of alkyl styrene, halogenated styrene, and halogenated alkyl styrene. The method of claim 1, wherein the solvent of step a) is at least one selected from the group consisting of normal hexane, cyclohexane, toluene, ethyl benzene, and benzene. delete The method of claim 1, wherein the input of the low-temperature initiator in step b) is 100 to 1000 ppm. According to claim 1, wherein step b) is a method for producing a rubber-modified styrene resin, characterized in that for 2 to 4 hours after the low-temperature initiator is added. delete The method of claim 1, wherein the low temperature initiator of step b) is selected from the group consisting of a peroxyester-based initiator and a peroxydicarbonate-based initiator. 12. The method of claim 11, wherein the peroxyester family initiator is selected from the group consisting of 1,1-dimethyl-3-hydroxybutyl, alpha-cumyl, t-cumyl and t-butyl peroxyneodecanoate. Species or more, and the initiator of the peroxydicarbonate series is one selected from the group consisting of diisopropyl, di-3-methoxybutyl, di (2-ethylhexyl) and di-sec-butyl peroxydicarbonate The manufacturing method of the rubber modified styrene resin characterized by the above. delete As a rubber-modified styrene-based resin produced by any one of claims 1 to 6, 8, 9, 11 and 13, In the resin, the rubber particles are composed of 50 to 99% of rubber particles having an average particle diameter of 0.1 to 0.5 µm and 1 to 50% of rubber particles having an average particle diameter of 1 to 5 µm.