JP2804967B2 - Method for producing rubber-modified aromatic monovinyl resin - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a method for producing a rubber-modified aromatic monovinyl resin. More specifically, the present invention is a rubber having excellent impact resistance, excellent fluidity, heat resistance, rigidity, etc., and a good balance of physical properties, which is suitable as a material for OA equipment, home appliances, automobile parts and the like. The present invention relates to a method for efficiently producing a modified aromatic monovinyl resin.

[Prior Art] Conventionally, in order to improve the impact resistance of polystyrene, styrene is polymerized in the presence of a rubber-like polymer, whereby styrene is partially graft-polymerized to the rubber-like polymer, and styrene is polymerized. Is a polystyrene resin, which is substantially a mixture of a rubbery polymer / styrene graft copolymer and polystyrene, so that a so-called rubber-modified polystyrene resin is industrially used.

As this rubbery polymer, polybutadiene rubber and styrene-butadiene copolymer rubber are generally used.

Such a rubber-modified polystyrene resin, that is, impact-resistant polystyrene, is widely used in various applications because of its excellent impact resistance and rigidity and good moldability.

Meanwhile, as a method for improving the impact resistance of the rubber-modified polystyrene resin, a method for increasing the amount of a rubbery polymer is known. However, when a large amount of the rubber-like polymer is used, there is a problem that physical properties such as fluidity, heat resistance, and rigidity cannot be reduced.

On the other hand, since the development of impact resistance in the rubber-modified polystyrene resin depends on the soft component (rubber-like polymer / rubber-like polymer-styrene graft copolymer), a rubber-modified polystyrene resin having excellent impact resistance is used. To get
It is also known that it is necessary to control the composition and structure of the soft component. It is also known that the swelling index of the soft component is one of the indices indicating the composition and structure of the soft component, and that the swelling index has a region where the impact resistance is maximized.

However, the swelling index of the soft component is usually higher in a post-treatment step (a devolatilization step, a granulation step, etc.) at a high temperature.
The rubber-like polymer is lowered by causing an excessive crosslinking reaction. As a method of controlling such a swelling index, for example, a method of controlling the swelling index from a polymerization step using a high cis polybutadiene rubber and a phenolic antioxidant has been proposed (Japanese Patent Application Laid-Open No. 62-74944). This method is not necessarily a satisfactory method for sufficiently controlling the swelling index of the soft component.

[Problems to be Solved by the Invention] The present invention provides a rubber-modified aromatic monovinyl-based resin having excellent impact resistance, good fluidity, heat resistance, rigidity, etc., and excellent physical property balance. It was made for the purpose.

[Means for Solving the Problems] The present inventors have conducted intensive studies to develop a rubber-modified aromatic monovinyl-based resin having such preferable properties, and as a result, have found that 5 to 30% by weight of a rubber-like polymer has been obtained. By polymerizing the aromatic monovinyl monomer solution containing, when producing a rubber-modified aromatic monovinyl resin, a phenolic thermal degradation inhibitor is added at a specific stage, in a post-treatment step,
By adjusting the soft component in the obtained rubber-modified aromatic monovinyl resin, that is, the swelling index of the toluene-insoluble component to a specific range, it was found that the above object can be achieved, and the present invention was completed based on this finding. I came to.

That is, in the present invention, an aromatic monovinyl-based monomer solution containing 5 to 30% by weight of a rubbery polymer is polymerized to produce a rubber-modified aromatic monovinyl-based resin. At least 65%, a phenolic thermal deterioration inhibitor is added, and then devolatilization treatment or further polymerization is carried out, and then a rubber-modified aromatic monovinyl resin obtained by devolatilization treatment is added. The present invention provides a method for producing a rubber-modified aromatic monovinyl-based resin, characterized in that the swelling index of the toluene-insoluble component is adjusted to a range of 11 to 15.

 Hereinafter, the present invention will be described in detail.

In the method of the present invention, examples of the aromatic monovinyl monomer used as one component of the raw material include styrene alone or a mixture with another vinyl monomer copolymerizable with styrene. Examples of the copolymerizable monomer include α-methylstyrene, o-methylstyrene,
Aromatic monovinyl compounds such as m-methylstyrene, p-methylstyrene, vinylethylbenzene, vinylxylene, pt-butylstyrene, α-methyl-p-methylstyrene, vinylnaphthalene, methyl methacrylate, ethyl methacrylate, acrylic Examples include methyl acrylate, acrylonitrile, methacrylonitrile, methacrylic acid, acrylic acid, maleic anhydride, phenylmaleimide, and halogen-containing vinyl monomers. These copolymerizable monomers may be used alone or in a combination of two or more, but usually 30% by weight or less, preferably 10% by weight, based on all monomers containing styrene. %.

In the method of the present invention, examples of the rubbery polymer used as another component of the raw material include polybutadiene, styrene-butadiene copolymer, polyisoprene, butadiene-isoprene copolymer, and natural rubber.
The polybutadiene may be low-cis polybutadiene or high-cis polybutadiene, and the styrene-butadiene copolymer (SBR) may be a random type or a block type. . Among these rubbery polymers, polybutadiene and styrene-butadiene copolymer are particularly preferred.

In the present invention, one type of these rubbery polymers may be used, or two or more types may be used in combination, and based on the total weight with the aromatic monovinyl monomer,
It is necessary to dissolve in the monomer so as to be 5 to 30% by weight. If the amount is less than 5% by weight, the impact resistance is insufficient, and if it exceeds 30% by weight, the viscosity of the polymerization system becomes too high, which leads to unfavorable situations such as easy operation troubles. I do.

The phenolic thermal deterioration inhibitor used in the method of the present invention is a phenolic compound having a structure capable of effectively capturing and stabilizing radicals generated under oxygen-free conditions, and is structurally Are particularly effective. As such, for example, 2-t-butyl-6- (3-t-butyl-
2-Hydroxy-5-methylbenzyl) -4-methylphenyl acrylate [Sumilyzer GM, Sumitomo Chemical Co., Ltd.
Manufactured, trade name], 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methyl-methylbenzyl) -4
-Methylphenyl acrylate, 2,5-di-t-butyl-6- (3,5-di-t-butyl-2-hydroxymethylbenzyl) phenyl acrylate, and the like.

One of these phenolic thermal deterioration inhibitors may be used alone, or two or more of them may be used in combination. The amount of the phenolic thermal degradation inhibitor is usually the total amount of the aromatic monovinyl monomer and the rubbery polymer. Is selected in the range of 0.01 to 0.5% by weight.
If this amount is less than 0.01% by weight, the effect of preventing thermal deterioration may not be sufficiently exerted, and if it exceeds 0.5% by weight, no improvement in the effect is recognized in proportion to the amount.

There is no particular limitation on the polymerization method in the present invention,
Conventionally used methods such as emulsion polymerization, bulk polymerization, solution polymerization, suspension polymerization, and multistage polymerization such as bulk-suspension two-stage polymerization can be used.

Next, as a process having a devolatilization step, a bulk polymerization method will be described as an example.First, a required amount of a rubber-like polymer is dissolved in an aromatic monovinyl-based monomer, and a polymerization initiator is optionally provided. The polymerization reaction is carried out by adding an organic peroxide as the above. The polymerization reaction temperature is usually selected from the range of 20 to 200 ° C. depending on the decomposition temperature when an organic peroxide is used, and usually 50 to 200 ° C. when no organic peroxide is used.
It is selected in the range of 250 ° C. In this bulk polymerization method, a solvent, a chain transfer agent, a general antioxidant, a mineral oil, a silicone oil, and the like can be appropriately added as required.

Next, when the polymerization rate of the aromatic monovinyl monomer reaches 65% or more, preferably 75% or more, a required amount of the phenolic thermal deterioration inhibitor is added, and then the unreacted aromatic monovinyl monomer is added. The desired rubber-modified aromatic monovinyl-based resin is obtained by devolatilization to remove volatile components such as the system monomer, or, if necessary, by further proceeding the polymerization, followed by devolatilization. Can be

In this bulk polymerization, it is preferable to carry out the polymerization until the polymerization rate finally reaches 70% or more. The devolatilization treatment includes, for example, a flash drum, a twin-screw devolatilizer, a thin film evaporator, and an extruder. Etc. can be used.

As the organic peroxide used as desired,
For example, 2,2-bis (t-butylperoxy) butane, 2,2
-Bis (t-butylperoxy) octane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, n-butyl-4, Peroxyketals such as 4-bis (t-butylperoxy) valerate;
-Butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α'-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2 , 5-Dimethyl-2,5-di (t-butylperoxy) hexane-
3, dialkyl peroxides such as 3, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide,
Diacyl peroxides such as benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, m-trioyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexylperoxydicarbonate, di-n-propylperoxydicarbonate, dimyristyl peroxydicarbonate , Di-2-ethoxyethylperoxydicarbonate, dimethoxyisopropylperoxydicarbonate, di- (3-methyl-
Peroxydicarbonates such as 3-methoxybutyl) peroxydicarbonate, t-butylperoxyacetate, t-butylperoxyisobutyrate, t-butylperoxyisobutyrate
Butyl peroxy pivalate, t-butyl peroxy neodecanoate, cumyl peroxy neodecanoate,
t-butylperoxy-2-ethylhexanoate, t
-Butylperoxy-3,3,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate, di-tert-butyldiperoxyisophthalate, 2,5-dimethyl-2,5-di ( Peroxyesters such as benzoylperoxy) hexane and t-butylperoxyisopropyl carbonate; ketone peroxides such as acetylacetone peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide; t-butyl hydroperoxide , Cumene hydroperoxide,
Diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, 2,5-dimethylhexane-2,5
Hydroperoxides such as -dihydroperoxide and 1,1,3,3-tetramethylbutyl hydroperoxide. These organic peroxides may be used alone or in combination of two or more.

As the solvent used as desired, aromatic hydrocarbons, such as toluene, xylene, and ethylbenzene, are preferably exemplified. These aromatic hydrocarbons are 1
Seeds may be used, or two or more kinds may be used as a mixture,
Further, other solvents as long as the dissolution of the polymerization product is not impaired,
For example, they can be used in combination with aliphatic hydrocarbons and dialkyl ketones. The amount of the solvent used is desirably 25% by weight or less based on the total amount of the rubbery polymer and the aromatic monovinyl monomer, and if it exceeds 25% by weight, the polymerization rate is significantly reduced, The impact strength of the resulting rubber-modified aromatic monovinyl resin tends to decrease, and a large amount of energy is required to recover the solvent, which is economically disadvantageous. The solvent may be added at the time when the polymerization proceeds and the viscosity becomes relatively high, or may be added before the polymerization. However, in view of uniformity of quality, control of the polymerization temperature, etc., 5
Advantageously, it is added in a proportion of up to 15% by weight.

Further, as a chain transfer agent used as desired,
Examples thereof include mercaptans such as α-methylstyrene dimer, n-dodecylmercaptan, t-dodecylmercaptan, 1-phenylbutene-2-fluorene, dibenthene and chloroform, terpenes, and halogen compounds.

Next, the bulk-suspension two-stage polymerization method will be described as an example. First, in the same manner as in the above-described bulk polymerization method, prepolymerization by the bulk polymerization method is performed until the polymerization rate becomes about 10 to 60%. Is performed, the prepolymerized solution is suspended in an aqueous medium using a suspending agent such as tribasic calcium phosphate or polyvinyl alcohol or a suspending agent and a surfactant, and the polymerization rate is almost 100%. The suspension polymerization is carried out until it becomes close, then the slurry containing the suspended polymer particles is treated by ordinary means, the bead-like reactant is taken out, dried, and then the required amount of the phenolic thermal degradation inhibitor is added thereto. Is added and granulated by an extruder to obtain a desired rubber-modified aromatic monovinyl resin.

In any of the polymerization methods such as the bulk polymerization method and the bulk-suspension two-stage polymerization method, if the phenolic thermal deterioration inhibitor is added in the initial stage of polymerization, radicals during the polymerization reaction are trapped, which is not preferable. .

The thus obtained rubber-modified aromatic monovinyl-based resin must have a toluene-insoluble content, that is, a swelling index of a soft component in the range of 11 to 15. If the swelling index deviates from the above range, the impact resistance tends to decrease, and the object of the present invention cannot be sufficiently achieved. The swelling index of the toluene-insoluble component can be adjusted by the temperature, the treatment time, and the like in the devolatilization treatment step.

The swelling index of the toluene-insoluble component in the present invention is a value obtained by the following method. That is, after dissolving 2.0 g of the sample resin in 100 ml of toluene, the insoluble matter is separated by centrifugation and weighed, and this is defined as Ag. Next, the wet insoluble matter is reprecipitated with methanol, vacuum-dried for one day and weighed, and weighed as Bg. The swelling index of the toluene insoluble matter is represented by A / B.

The rubber-modified aromatic monovinyl resin obtained by the method of the present invention may contain, if desired, various commonly used additives such as stearic acid, pehenic acid, zinc stearate, calcium stearate, and stearic acid. Magnesium, lubricants such as ethylene bis stearamide, organic polysiloxane, mineral oil, or 2,
6-di-t-butyl-4-methylphenol, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, triethylene glycol-bis-3- (3-t-butyl- Hindered phenols such as 4-hydroxy-5-methylphenyl) propionate, tri (2,4-di-t-butylphenyl) phosphite, 4,4'-butylidenebis (3-methyl-6-t-butylphenyl) Phosphorus-based antioxidants such as -di-tridecyl) phosphite, other ultraviolet absorbers, antistatic agents,
Release agents, plasticizers, dyes, pigments, various fillers, and the like can be added. Further, other polymers, for example, general polystyrene, polyphenylene ether and the like can also be blended.

[Examples] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

 The properties of the resin were determined by the following methods.

(1) Swelling index of toluene-insoluble content It was determined by the above method.

(2) Izod impact strength Determined in accordance with JIS K-6871 (notched).

(3) Drop weight impact strength Load is applied at the center of the board width (70 mm) at a point 125 mm from the gate position (less than the formed board) of an injection-molded board of 270 x 70 x 3 mm.
3.76 kg, speed 3.5 m / s, hole diameter of sample fixing part 2 inches, temperature
At 23 ° C, Rheometrics automatic falling weight impact tester RDT-
The energy was measured using a 5000, and the energy up to the point where the force suddenly decreased sharply in the curve of the force and the displacement was obtained and defined as the falling weight impact strength.

Example 1 90 parts by weight of styrene, 10 parts by weight of polybutadiene rubber (A), and Irganox 1076: n-octadecyl-3- (3,
5-Di-t-butyl-4-hydroxyphenyl) propionate (antioxidant, trade name, manufactured by Ciba-Geigy) 0.15
A part by weight was dissolved and supplied to a first polymerization vessel having a capacity of 23 l at a rate of 18 l / hr, and polymerization was carried out at a temperature of 135 ° C. and a stirring speed of 200 rpm. Next, this partial polymerization solution was continuously supplied to a second polymerization device and a third polymerization device each having a capacity of 33 l, and polymerization was performed at a temperature of 135 ° C to 180 ° C with stirring. The polymerization rates of styrene at each stage were 20%, 60%, and 85%, respectively.

To the obtained polymerization reaction solution, 0.2 parts by weight of Sumilizer GM (trade name, manufactured by Sumitomo Chemical Co., Ltd.) was added, volatile matter was removed through a devolatilization step, and the pellet was formed. It was created. The physical properties of this test piece were
It is shown in the table.

Comparative Example 1 The procedure of Example 1 was repeated, except that Sumilizer GM was not added. Table 1 shows the results.

Comparative Example 2 In Example 1, the addition position of the Sumilizer GM was changed to the second position.
The procedure was carried out in the same manner as in Example 1 except that the inlet of the polymerization vessel was used. Table 1 shows the results.

Comparative Example 3 Example 1 was carried out in the same manner as in Example 1, except that the addition position of the Sumilizer GM was used as a raw material. Table 1 shows the results.

Example 2 In Example 1, except that the amount of styrene and polybutadiene rubber (A) used was changed as shown in Table 1,
It carried out similarly to Example 1. Table 1 shows the results.

Comparative Example 4 The procedure of Example 2 was repeated, except that Sumilizer GM was not added. Table 1 shows the results.

Comparative Example 5 The same procedure as in Example 2 was carried out except that Sumilizer GM was not added and Irganox 1076 was added at the outlet of the third polymerization vessel. Table 1 shows the results.

Comparative Example 6 In Example 2, the addition position of the Sumilizer GM was changed to the third position.
The procedure was carried out in the same manner as in Example 2 except that the inlet of the polymerization vessel was used. Table 1 shows the results.

Comparative Example 7 In Example 2, except that the amounts of styrene and polybutadiene rubber (A) used were changed as shown in Table 1,
It carried out similarly to Example 2. Table 1 shows the results.

Example 3 In Example 1, the amount of styrene shown in Table 1 was used, and instead of the polybutadiene rubber (A), the amount of styrene-butadiene copolymer rubber (B) shown in Table 1 was used. Example 3 was carried out in the same manner as in Example 1 except that the polymerization conversion rate at the outlet of the three polymerization reactors was changed to 75%. Table 1 shows the results.

Comparative Example 8 Example 3 was carried out in the same manner as in Example 3 except that Sumilizer GM was not added. Table 1 shows the results.

Comparative Example 9 The same procedure was performed as in Example 3 except that the amounts of styrene and the styrene-butadiene copolymer rubber (B) were changed as shown in Table 1. Table 1 shows the results.

[Effects of the Invention] According to the method of the present invention, it is possible to easily produce a rubber-modified aromatic monovinyl resin having excellent impact resistance, good fluidity, heat resistance, rigidity and the like, and excellent physical property balance. it can.

The rubber-modified aromatic monovinyl-based resin has the above-described excellent characteristics, and thus is suitably used as a material for, for example, OA equipment, home appliances, and automobile parts.

Claims (2)

(57) [Claims] An aromatic monovinyl monomer solution containing 5 to 30% by weight of a rubbery polymer is polymerized to produce a rubber-modified aromatic monovinyl resin. At least when it reaches 65%, a phenolic thermal deterioration inhibitor is added, and then devolatilization treatment or further polymerization is performed, and then the rubber-modified aromatic monovinyl resin obtained by devolatilization treatment is added. A method for producing a rubber-modified aromatic monovinyl-based resin, wherein the swelling index of a toluene-insoluble component is adjusted to a range of 11 to 15. 2. The method according to claim 1, wherein the amount of the phenolic thermal deterioration inhibitor is 0.01 to 0.5% by weight based on the total amount of the aromatic monovinyl monomer and the rubbery polymer.