JPH02185508A - Preparation of impact-resistant polystyrene - Google Patents

Abstract

PURPOSE:To improve impact resistance and luster by radical-polymerizing styrene in the presence of a specified polybutadiene rubber. CONSTITUTION:A polybutadiene rubber (A) consisting of a coupling polymer with a viscosity (at 25 deg.C in 5wt.% styrene soln.) of 200cps or larger, a vinyl bond content of 20% or less, an average particle diameter of rubber particles dispersed in the obtd. resin of 0.3-5mum and an inherent viscosity (measured at 25 deg.C in toluene) of 0.5dl/g is obtd. by treating active terminals of a polymer obtd. by polymerizing a monomer contg. 70wt.% or more butadiene in the presence of an org. Li compd. catalyst with a coupling agent (e.g. CH3SiHCl2). Then, 97-85wt.% styrene (B) is radical-polymerized in the presence of 3-15wt.% component A in an inert gas atmosphere at 60-200 deg.C.

Description

Detailed Description of the Invention a. Industrial Application Field The present invention is used as a molding material for various molded products that require excellent impact resistance and good gloss, such as electrical products, furniture, and building materials. The present invention relates to a method for producing high-impact polystyrene.

b. Conventional technology and issues Impact-resistant polystyrene resins are widely used as molding materials for molded products that require impact resistance because they have excellent moldability and various other physical properties in addition to impact resistance. . However, in order to expand its use and improve the quality of the resulting products, it is desired that it have excellent impact resistance and good gloss.

Generally, in order to improve the gloss of impact-resistant polystyrene-based resins, it is necessary to use polybutadiene as a raw material with a low solution viscosity. However, when polybutadiene having a low solution viscosity is used, a problem arises in that impact resistance is reduced. That is, in impact-resistant polystyrene resin,
Gloss and impact resistance are contradictory properties, and it has been difficult to obtain an impact-resistant polystyrene resin with good gloss without reducing impact resistance.

To solve this problem, methods using high viscosity polybutadiene rubber or solution polymerized SBR have been proposed (
JP-A-61-143414, JP-A-63-16271
No. 3).

However, with the recent expansion in the use of impact-resistant polystyrene, even higher impact strength has been required.

Therefore, an object of the present invention is to provide an impact-resistant polystyrene resin composition having excellent impact resistance and good gloss.

As a result of various studies, the present inventors found that using a polybutadiene rubber that has been treated with a coupling agent and has a solution viscosity and a vinyl bond content within a specific range, the diameter of the rubber particles dispersed in the resulting resin and the intrinsic viscosity of the resin. are adjusted to a specific range, or by using a butadiene-isoprene copolymer rubber whose solution viscosity, vinyl bond content, and isoprene content are within specific ranges, the diameter of the rubber particles dispersed in the resulting resin and the intrinsic viscosity of the resin are adjusted. The inventors have discovered that impact-resistant polystyrene that can achieve the above objectives can be obtained by adjusting each of them to specific ranges, and have thus arrived at the present invention.

Means for Solving Problem C1 That is, the present invention provides (A): a method for producing impact-resistant polystyrene by radically polymerizing styrene in the presence of polybutadiene rubber, in which butadiene is used as the polybutadiene rubber; A coupling polymer in which the active end of the polymer obtained by polymerizing a monomer mainly composed of using a catalyst such as an organolithium compound is treated with a coupling agent, % styrene solution with a viscosity of 250 centipoise or more, ■ a vinyl bond amount of 20% or less, and the average particle size of the rubber particles dispersed in the resulting resin to be in the range of 0.3 to 5 μm, A method for producing impact-resistant polystyrene, characterized in that the intrinsic viscosity of the resin is adjusted to a range of 0.5 cU/g or more (in toluene at 25° C.), and (B): in the presence of butadiene-isoprene copolymer rubber. In the method for producing high-impact polystyrene by radical polymerization of styrene, the butadiene isoprene copolymer rubber has: (1) a viscosity of a 5 weight % styrene solution measured at 25°C of 250 centipoise or more; (2) a vinyl bond in the butadiene moiety; The amount of gold is 20% or less, and the isoprene content in the copolymer is 1 to 30% by weight, and the average particle diameter of the rubber particles dispersed in the resulting resin is 0.3 to 5μ of steel. In the range, the intrinsic viscosity of the resin is 0.5d.
1/g (in toluene at 25°C) or more.

The polybutadiene rubber used in the above invention (8) is:
It is a coupling polymer obtained by polymerizing a monomer mainly composed of butadiene, preferably using an organic lithium compound as a catalyst, and treating the active end of the obtained polymer with a camping agent. The amount of the coupling agent to be used is preferably 0.1 times or more by mole, more preferably 0.1 times the mole of the active end (or the organic lithium compound if an organic lithium is used).
．． 15 to 0.8 mole times, particularly preferably 0.3 to 0.6 times
It is twice the mole. As the coupling agent, silicon tetrachloride, alkyldichlorosilane, tin tetrachloride divinylbenzene, etc. are used.

Furthermore, in terms of reducing fish eyes, a bifunctional coupling agent is preferable, and a silane type coupling agent is preferable. Particularly preferred among these are alkyldichlorosilanes. As the alkyldichlorosilane, Cll:+
5iHCf 2 , CzllsSil(Cj2 z ,
C3H75iHCE 2, C4) 1gsi) IC12z
etc. can be used.

The polybutadiene rubbers include those obtained by copolymerizing butadiene with a conjugated diene such as isoprene, an aromatic vinyl compound such as styrene, a monovinyl cyanide compound such as acrylonitrile, or an acrylic ester such as HMA.

The copolymerization ratio of these copolymerization components is preferably 30% by weight or less, more preferably 20% by weight or less,
Particularly preferably, it is 15% by weight or less.

The butadiene-isoprene copolymer rubber used in the above invention (B) is obtained by solution polymerizing butadiene and isoprene using, for example, an organolithium compound as a catalyst.

of the polybutadiene rubber used in the above invention (A) and the butadiene-isoprene copolymer rubber (hereinafter collectively referred to as the rubber component) used in the above invention (B) at 25°C.
The solution viscosity of the 5% by weight styrene solution is 200 centipoise or more, preferably 250 to 2000 centipoise, more preferably 500 to 1700 centipoise, particularly preferably 600 to 1500 centipoise. With an ungrooved solution viscosity of 200 centipoise, it is difficult to simultaneously achieve the particle size and intrinsic viscosity of the rubber particles dispersed in polystyrene specified in the present invention, resulting in poor impact resistance.

In addition, a solution viscosity exceeding 2000 centivoise is undesirable because the solubility in styrene decreases significantly and it takes a long time for dissolution to reduce productivity when producing the impact-resistant polystyrene.

The amount of vinyl bond gold in the rubber component of the present invention (the amount of vinyl bond gold in the butadiene portion in the butadiene isoprene copolymer rubber) is 20% or less, preferably 12 to 17%, and more preferably 13 to 16%. If it exceeds 20%, the gloss will be good but the impact resistance at low temperatures will decrease.
Undesirable.

The isoprene content of the butadiene-isoprene copolymer rubber used in the present invention (B) is 1 to 30% by weight, preferably 2 to 20% by weight, and more preferably 4 to 15% by weight.
It is. If it is less than 1% by weight, the resulting resin will have a lot of fins, which is not preferable. If it exceeds 30% by weight, impact resistance decreases, which is not preferable.

Further, the Mooney viscosity in the present invention (A) is preferably 80 to 200, more preferably 90 to 150,
The Mooney viscosity in the present invention (B) is preferably 60 to
200, more preferably 65-150.

In the present invention, while using the above rubber component,
The particle size of the rubber particles dispersed in the resulting resin and the intrinsic viscosity of the resin are adjusted to a specific range.

The average particle size of the rubber particles dispersed in the resulting resin is 0.
The total thickness is 3 to 5 μm, preferably 0.5 to 3 μm, more preferably 0.67 to 2.5 μm, particularly preferably 1 to 2 μm. If it is less than 0.3 μm, the impact resistance will be poor, and if it exceeds 5 μm, only a product with poor gloss will be obtained, and the tensile strength will also decrease.

In addition, the intrinsic viscosity of the resin must be 0.5 dl/g or more (in toluene at 25°C), preferably 0.7 to 1
．． It is 4a/g. If it is less than 0.5 dl/g, the impact resistance will be poor and undesirable.

In order to adjust the average particle diameter of the rubber particles to a specific range of 0.3 to 5 μm within the above-mentioned high intrinsic viscosity range, simply adjust the stirring rotation speed during graft polymerization as is usually done. It is difficult. That is, the amount of molecular weight modifier is very small, preferably 3 to styrene.
It is necessary to use the rubber component of the present invention with a solution viscosity of 0.00 ppm or less and the above-mentioned specific solution viscosity.

Further, the present invention uses the above-mentioned rubber component and graft-polymerizes styrene in the presence of this rubber.

The method of graft polymerization is not particularly limited, but may be carried out, for example, by bulk polymerization of a styrene solution in which the rubber component of the present invention is dissolved, or by radical polymerization by a combination of bulk and suspension polymerization.

The mixing ratio of the rubber component of the present invention and styrene is 3/97 to 15/85, preferably 4/96 to 10/9 in terms of weight percent.
It is 0. If the amount of the rubber component used in the present invention is less than 3% by weight, the resulting resin will have poor impact resistance, and if it exceeds 15% by weight, mechanical strength such as tensile strength will decrease, which is not preferred.

In the present invention, a part of styrene may be replaced with other vinyl monomers such as α-methylstyrene, acrylonitrile, methyl methacrylate, etc. during polymerization.

When the graft polymerization of the rubber component of the present invention and styrene is carried out by bulk polymerization, the rubber component of the present invention is dissolved in styrene, and then, if necessary, a molecular weight regulator within the above range is added and polymerized.

Examples of the molecular weight regulator include α-methylstyrene dimer, n-decylmercaptan, tert-dodecylmercaptan, 1-phenylbutene-2-fluorene, and mercaptans such as dipentene and chloroform;
Terpenes, halogen compounds, etc. are used.

Furthermore, a common lubricant is added to improve the moldability of the resulting resin. Examples include ester lubricants such as butyl stearate and butyl fucurate, lubricants used in conventional resin processing such as mineral toil and paraffin wax.

After dissolving these molecular weight regulators and lubricants in the polymer solution, benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, methyl ethyl ketone peroxide, dicumyl peroxide, diisopropyl peroxydicarbonate, and tertiary peroxide are added as initiators. -butylperoxyacetate, di-tert-butylciba-oxyisophthalate, 2
, 5-dimethyl 2,5-di(t-butylperoxy)hexane or azobisisobutyronitrile, etc., and the reaction temperature is 60 to 200'C under an inert gas atmosphere.
Complete the reaction while stirring.

In addition, when thermal polymerization is carried out without a catalyst, it is usually 100 to 200'
Polymerization is carried out by heating at C to complete the reaction.

During the bulk polymerization reaction, it is usually preferable to stir effectively until the polymerization rate of styrene reaches about 30%, and in particular in the present invention, stirring is preferably carried out so that the dispersed rubber particle size falls within the range of the present invention. On the other hand, it is preferable to moderate the stirring after the degree of styrene polymerization exceeds about 30%.

Further, at this time, a hydrocarbon solvent such as toluene, ethylhenzene, xylene, etc. may be added in order to reduce the viscosity of the polymerization system.

After the polymerization is completed, the monomer and solvent are recovered by removing the monomer and the solvent using a vent-type router or steam stripping.

In addition, in the case of radical polymerization by a combination of bulk polymerization and suspension polymerization, first about 10 to 4
After carrying out bulk polymerization until 5% by weight is converted into a polymer, the reaction solution is dispersed in an aqueous solution containing a suspension stabilizer such as polyvinyl alcohol, polymethacrylate, or tribasic calcium phosphate to form a suspension. Reaction temperature 6 while maintaining
Polymerization is completed at 0-160°C. After the polymerization is completed, the suspension stabilizer is removed by thorough washing with water, and the polymer resin is recovered after drying.

In addition, known antioxidants, such as 2,6-tert-butyl-4 methylphenol, 2-(1-methylcyclohexyl 4,6
-dimethylphenol, 2,2'-methylene-bis(
4-ethyl-6-tert-butylphenol), 4.
4'-thiobis-(6tert-butyl-3-methylphenol), dilaurylthiodipropionate, tris(di-nonylphenyl)phosphite, wax; known UV absorbers such as p-tert-butylphenyl salicic rate, 2゜2'-dihydroxy-4-methoxyhensiphenone, 2-(2'-hydroxy-4'
-n-octoxyphenyl) benzothiriazole; known lubricants such as paraffin wax, stearic acid, hydrogenated oils, stearamide, methylene bis stearamide,
n-methyl stearate, ketone wax, octyl alcohol, lauryl alcohol, hydroxystearic acid triglyceride; known flame retardants such as antimony oxide, aluminum hydroxide, zinc borate, tricresyl phosphate, chlorinated paraffin, tetrabromobutane, hexa Bromobenzene, tetrabromobisphenol A;
Known antistatic agents, such as stearamidopropyl dimethyl-β-hydroxyethylammonium nitrate;
Known colorants such as titanium oxide, carbon black,
Other inorganic or organic pigments; known fillers such as calcium carbonate, clay, silica, glass fibers, glass spheres, carbon fibers, etc. can be added as required.

d. Examples Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

In the examples, parts and % mean parts by weight and % by weight unless otherwise specified.

Moreover, various measurements in the examples were carried out according to the methods shown below.

The solution viscosity of a 5% by weight styrene solution of the polybutadiene and butadiene-isoprene copolymer rubber was measured at 25° C. using a Cannon-Fenske viscometer. The microstructure was determined by infrared spectroscopy (Morello method).

The isoprene content of the butadiene-isoprene copolymer rubber was measured by infrared spectroscopy.

The physical properties of the impact-resistant polystyrene were measured by molding the obtained resin pellets using an 80□ injection molding machine at a cylinder temperature of 200° C. to prepare a test piece, and using the following method.

Izot impact strength (1 part 4 inches, notched): Measured according to 8 STM D-256.

Gloss (60℃ reflection gloss): ASTM D-53
Measured according to 2.

Tensile strength: Measured according to ASTM D-638.

Fisheye: Pellets are made by extruder at 0,2
It was extruded to a thickness of mm, and the number of fish eyes with a diameter of 0.2 mm or more per area of 10 cm x 10 cm was measured.

Particle size of dispersed rubber particles: 1 to 2 resin pellets are placed in about 50 mm of dimethylformamide and left for about 3 hours.

This dimethylformamide solution was mixed with an electrolyte solution (ISO
TON II) and measured with a Coulter Counter Model T^-2 to obtain an appropriate particle concentration, and from the obtained particle size distribution, the 50% median particle size was calculated, and this was taken as the average particle size.

Intrinsic viscosity: After dissolving the resin pellets in toluene, they were separated into a rubber component and a resin component using a centrifuge, and the resulting resin component was measured in toluene at 25° C. using an Uherode viscometer.

Example 1 Two 152 polymerization reactors equipped with a stirrer and jacket were connected in succession, and 1500 g of butadiene was added from the bottom of the first reactor.
/Hr, cyclohexane 15000g/Hr, n-
Butyl lithium was continuously supplied using a metering pump at a flow rate of 1.00 g/Hr and tetrahydrofuran was 0.7 g/Hr, and the inside of the polymerization reactor was maintained at 88° C. from beginning to end for polymerization.

The polymerization solution withdrawn from the top of the first reactor is continuously fed to the bottom of the second reactor.

Methyldichlorosilane was continuously supplied as a coupling agent from the bottom of the second reactor at a flow rate of 0.90 g/Hr (addition amount is 0.5 mole times relative to lithium) using a metering pump to react. The inside of the vessel was kept at 70″C throughout.

0.5 part of 2.6-tert- per 100 parts of polymer was added to the polymerization solution continuously drawn out from the top of the second reactor.
Butyl-p-cresol was added. The resulting polymer solution was desolvated by steam stripping and dried with a hot roll at 110°C to obtain polybutadiene rubber A.

Table 1 shows the measurement results of physical properties.

Using this polybutadiene rubber A, graft polymerization was carried out in the following manner.

A solution in which parts by weight of polybutadiene rubber were dissolved in 93 parts by weight of styrene was transferred to a polymerization reactor equipped with a ribbon vane stirrer with an internal volume of IQffi, and 150 ppm of tert-dodecyl mercaptan was added to the styrene. The polymerization rate of styrene is approximately 30 at 300 rpm and 118°C.
%.

Next, 0 parts of dicumyl peroxide per 100 parts of polymerization solution.
．． Further, 150 parts of water containing 3 parts of tribasic calcium phosphate as a suspension stabilizer and 0.005 parts of sodium dodecylhenzenesulfonate as a surfactant were added, and the mixture was suspended with stirring.

This suspension mixture was heated at 120° C. for 2 hours with stirring for 14 hours.
Polymerization was carried out by heating at 0°C for 2 hours and then at 160°C for 2 hours.

The resulting bead-shaped resin was filtered, washed with water, dried, and pelletized using an extruder.

The impact-resistant polystyrene thus obtained was injection molded to prepare test pieces for measuring physical properties, and the physical properties were evaluated. The measurement results are shown in Table-2.

Examples 2 to 5, Comparative Example 1. 3 Polybutadiene rubber B- was prepared in the same manner as in Example 1 except that the amounts and types of n-butyllithium, tetrahydrofuran, and coupling agents were changed, but the solution viscosity, the amount of vinyl bond, the amount and type of coupling agents used were different. I got a G.

Using these polybutadiene rubbers B-G, graft polymerization was carried out in the same manner as in Example 1 to obtain impact-resistant polystyrene. Table 2 shows the measurement results of the physical properties of these resins.
Shown below.

Comparative Example 2 Comparative example 2 was carried out in the same manner as in Example 1 except that polybutadiene rubber A was used and tert-dodecyl mercaptan was changed to 11,000 ppp relative to styrene. The physical properties of the obtained resin are shown in Table 2.

As is clear from the results shown in Tables 1 and 2, the resins obtained in Examples 1 to 5 are excellent in Izot impact strength, gloss, and tensile strength.

The resin of Comparative Example 1 has a large amount of vinyl bond in the polybutadiene rubber, and the resin has poor Izot impact strength at -25°C. Furthermore, the average particle diameter and intrinsic viscosity of the rubber particles of the resin of Comparative Example 2 are outside the range of the present invention, and the resin has poor gloss and Izot impact strength. The resin of Comparative Example 3 has an average particle diameter outside the range of the present invention and is inferior in Izot strength.

Example 6 15I with stirrer and jacket! Using a polymerization reactor, butadiene 1395g/Hr, isoprene 105g/Hr, and cyclohexane 15000g/Hr were added from the bottom of the polymerization reactor.
Hr, n-butyllithium was continuously supplied using a metering pump at a flow rate of 0.53 g/Hr, and tetrahydrofuran was 0.7 g/Hr.
Polymerization was carried out while maintaining the temperature at °C.

0.5 part of 2,6-sheet tert per 100 parts of polymer is added to the polymerization solution continuously withdrawn from the top of the polymerization reactor.
Butyl to p-cresol was added. The obtained polymerization solution was desolvented by steam stripping and dried with a hot roll at 110°C to obtain butadiene-isoprene copolymer rubber P.
I got it. The measurement results of physical properties are shown in Table 3.

Using this butadiene-isoprene copolymer rubber P, graft polymerization was carried out in the following manner.

A solution of 7 parts by weight of butadiene-isoprene copolymer rubber P dissolved in 93 parts by weight of styrene was transferred to a polymerization reactor with an internal volume of 10ffi equipped with a ribbon blade stirrer, and after adding 150 ppm of tert-dodecyl mercaptan to the styrene, the solution was rotated. Polymerization was carried out at several 30 rpm and 118'C until the polymerization rate of styrene reached about 30%.

Next, 0 parts of dicumyl peroxide per 100 parts of polymerization solution.
．． Further, 150 parts of water containing 3 parts of tribasic calcium phosphate as a suspension stabilizer and 0.005 parts of sodium dodecylbenzenesulfonate as a surfactant were added, and the mixture was suspended with stirring.

This suspension mixture was heated at 120° C. for 2 hours with stirring for 14 hours.
Polymerization was carried out by heating at 0''C for 2 hours and then at 160''C for 2 hours.

The resulting bead-shaped resin was filtered, washed with water, dried, and pelletized using an extruder.

The impact-resistant polystyrene thus obtained was injection molded to prepare test pieces for measuring physical properties, and extruded using an extruder.
A sheet piece for fisheye measurement was prepared and its physical properties were evaluated. The measurement results are shown in Table 4.

Examples 7-8, Comparative Examples 4-7 Solution viscosity, vinyl bond amount, and isoprene content were determined in the same manner as in Example 6 except that the amounts of butadiene and isoprene supplied and the amounts of n-butyllithium and tetrahydrofuran were changed. Different butadiene-isoprene copolymer rubbers Q~■ were obtained. Graft polymerization was carried out in the same manner as in Example 6 using these butadiene-isoprene copolymer rubbers Q-V to obtain impact-resistant polystyrene. Table 4 shows the measurement results of the physical properties of these resins.

Comparative Example 8 Using butadiene-isoprene copolymer rubber P, tert
-1000p of dodecyl mercaptan to styrene
It was carried out in the same manner as in Example 6 except that p111 was used. The physical properties of the obtained resin are shown in Table 4.

As is clear from the results shown in Tables 3 and 4, the resins obtained in Examples 6 to 8 were excellent in Izot impact strength, gloss, and tensile strength, and had fewer fish eyes.

On the other hand, the resin of Comparative Example 4 has a high isoprene content in the rubber component, so the Izot impact strength is poor. Since the resin of Comparative Example 5 has a low isoprene content in the rubber component, the resin has many fish eyes. In the resin of Comparative Example 6, the viscosity of the 5% by weight styrene solution of the rubber component was outside the range of the present invention, and the resin had poor Izot impact strength. In the resin of Comparative Example 7, the amount of vinyl bond in the rubber component was outside the range of the present invention, and the Izot impact strength at -25°C was poor. Furthermore, the average particle diameter and intrinsic viscosity of the rubber particles of the resin of Comparative Example 8 are outside the range of the present invention, and the resin has poor gloss and Izot impact strength.

e1 Effects of the Invention According to the present invention, impact-resistant polystyrene with excellent impact resistance and gloss can be obtained, and its industrial significance is extremely large.

Claims (2)

[Claims] (1) In a method for producing impact-resistant polystyrene by radically polymerizing styrene in the presence of a polybutadiene rubber, the activity of the polymer obtained by polymerizing a monomer mainly composed of butadiene as the polybutadiene rubber. A coupling polymer whose terminal end is treated with a coupling agent, wherein [1] the viscosity of a 5% by weight styrene solution measured at 25°C is 200 centipoise or more, [2] the amount of vinyl bond is 20% or less using
And the average particle diameter of the rubber particles dispersed in the resulting resin is in the range of 0.3 to 5 μm, and the intrinsic viscosity of the resin is 0.5 dl.
/g (in toluene at 25°C) or more. (2) In a method for producing impact-resistant polystyrene by radically polymerizing styrene in the presence of a butadiene-isoprene copolymer rubber, [1]
The viscosity of a 5% by weight styrene solution measured at 25°C is 200
Centipoise or more, [2] The amount of vinyl bond in the butadiene part is 20% or less,
[3] Isoprene content in the copolymer is 1 to 30% by weight
The average particle diameter of the rubber particles dispersed in the resulting resin was adjusted to a range of 0.3 to 5 μm, and the intrinsic viscosity of the resin was adjusted to 0.5 dl.
/g (in toluene at 25°C) or more.