JP2608481B2 - Styrene resin composition - Google Patents

Description

The present invention relates to a novel styrene resin composition. More specifically, the present invention relates to a diene-based rubber-like polymer and a styrene-based resin having excellent gloss and high impact strength, which are suitably used in the fields of OA equipment, home electric appliances, sheets, and the like, particularly having a surface impact strength. And a rubber-modified styrenic resin composition comprising:

[Prior art] Conventionally, in order to improve the impact resistance of a styrene resin,
By blending a rubber-like polymer with polystyrene, or by polymerizing styrene in the presence of a rubber-like polymer, styrene is partially graft-polymerized to the rubber-like polymer, and the rest of styrene becomes polystyrene. Thus, a so-called rubber-modified polystyrene resin composition (HIPS) in which a rubbery polymer / styrene graft copolymer and polystyrene are substantially mixed has been widely used.

In such a rubber-modified polystyrene resin composition, the rubber-like polymer is usually dispersed in the styrene-based resin in the form of particles, and the size of the particles is closely related to impact resistance, rigidity, and gloss. Is well known. That is, the rigidity and gloss are better as the size of the rubber-like polymer particles is smaller, but the impact resistance is reduced in proportion to the smaller size of the rubber-like polymer particles, and is lower than a certain limit. , The effect of improving the impact resistance is substantially lost.

In a conventional rubber-modified polystyrene resin composition,
In order to obtain the desired impact resistance, the rubbery polymer is dispersed in the polystyrene resin phase as particles having a particle size of 1 μm or more, usually in the range of 1 to 10 μm. There was a problem that restrictions on use were unavoidable.

Therefore, various attempts have recently been made to improve the balance between impact resistance and gloss. For example, a molding material made of impact-resistant polystyrene in which the particle size and structure of rubber-dispersed particles are controlled (German Patent No. No. 3345377),
Rubber-modified styrene copolymer in which the properties of the rubber polymer, the particle size of the dispersed particles, the graft ratio, etc. are controlled (JP-A-63-1997)
17 and 63-207803).

However, in these molding materials and copolymers, although the balance between impact resistance and gloss has been improved to some extent, it is not yet sufficient, and impact-resistant polystyrene with a better balance between impact resistance and gloss is used. The development of resin was desired.

[Problems to be Solved by the Invention] The present invention overcomes the drawbacks of the conventional impact-resistant polystyrene resin and has an excellent balance of physical properties such as high impact strength, particularly excellent surface impact strength and excellent gloss. The purpose of the present invention is to provide a rubber-modified styrenic resin composition.

Means for Solving the Problems The present inventors have conducted intensive studies to develop a rubber-modified styrenic resin composition having an excellent balance of physical properties as described above. time
By regulating the T _2, it found that can achieve the purpose, and completed the present invention based on this finding.

That is, the present invention provides a rubber-modified styrenic resin composition comprising a diene rubbery polymer and a styrene resin, wherein the diene rubbery polymer has a styrene content of 20 to
It is composed of 50% by weight of a styrene-butadiene block copolymer rubber or a polybutadiene rubber, and has an average particle diameter of 0.08 to 1.00 μm and a circumference parameter of 0.1 to 2.5 (μm) ^-1. %) ^-1 and a relaxation time T ₂ satisfies the conditions of 300 to 2000 μsec.

 Hereinafter, the present invention will be described in detail.

Examples of the styrene-based resin in the composition of the present invention include those containing an aromatic monovinyl compound unit alone or an aromatic monovinyl compound unit and a copolymerizable monomer unit.

Examples of the monomer constituting the aromatic monovinyl compound unit include styrene, α-alkyl-substituted styrene such as α-methylstyrene, α-ethylstyrene, α-methyl-p-methylstyrene, and o-methylstyrene. , M-methylstyrene, p-methylstyrene, 2,4
-Nucleic alkyl substituted styrene such as dimethylstyrene, ethylstyrene, ot-butylstyrene, pt-butylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-bromostyrene, dichlorostyrene, Dibromostyrene, trichlorostyrene,
Nuclear halogenated styrenes such as tribromostyrene, tetrachlorostyrene, tetrabromostyrene, and 2-methyl-4-chlorostyrene; and further, p-hydroxystyrene, o-methoxystyrene, vinylnaphthalene, and the like are included. In particular, styrene and α-methylstyrene are preferred. These aromatic monovinyl compounds may be used alone or in combination of two or more.

Further, as the monomer constituting the copolymerizable monomer unit, for example, acrylonitrile, methacrylonitrile,
Vinyl cyanide such as fumaronitrile, maleonitrile and α-chloroacrylonitrile are preferred, and among these, acrylonitrile is particularly preferred.
These vinyl cyanide may be used alone or in combination of two or more. However, the vinyl cyanide unit in the styrenic resin is 45% by weight or less, preferably 40% by weight or less.
It is advantageous to use it in a proportion of not more than% by weight. If the content of the vinyl cyanide unit exceeds 45% by weight in the styrenic resin, thermal stability, fluidity and the like are undesirably reduced.

Further, in the styrene resin, copolymerizable monomer units other than vinyl cyanide units, for example, maleic anhydride, itaconic anhydride, oxymaleic anhydride, citraconic anhydride, phenylmaleic anhydride, aconitic anhydride Unsaturated maleic anhydrides such as ethyl maleic anhydride and chloromaleic anhydride; maleimides such as maleimide and N-phenylmaleimide; methacrylic esters such as methyl methacrylate; acrylic esters such as methyl acrylate; methacrylic acid and acrylic acid One or two or more units of a monomer such as an unsaturated monocarboxylic acid may be contained in a proportion of 1 to 35% by weight.
Among these, a maleic anhydride unit is particularly preferred.

The diene rubbery polymer in the composition of the present invention comprises a styrene-butadiene block copolymer rubber having a styrene content of 20 to 50% by weight or a polybutadiene rubber.

The method for preparing the styrene resin composition of the present invention is not particularly limited, and a method conventionally used in preparing a rubber-modified styrene resin composition can be used. For example, it can be prepared by polymerizing an aromatic monovinyl compound or a monomer copolymerizable with an aromatic monovinyl compound in the presence of a diene rubber-like polymer. This polymerization method is not particularly limited, and conventionally used methods such as an emulsion polymerization method, a bulk polymerization method,
A multistage polymerization method such as a solution gunning method, a suspension polymerization method, or a bulk-suspension two-stage polymerization method can be used. Among these, a continuous bulk or solution polymerization method is preferred.

Next, an example of a preferred production method of the resin composition of the present invention by a continuous bulk or solution polymerization method will be described. First, an aromatic monovinyl compound or an aromatic monovinyl compound and vinyl cyanide or other copolymerizable To a mixture with various monomers, a diene rubber-like polymer is added, for example, 20 to
Dissolve at a temperature of 70 ° C. Next, this solution is supplied to one or more stages, preferably two or more stages of polymerization reactors equipped with a stirrer, and is usually polymerized at a temperature in the range of 70 to 150 ° C. A desired composition is obtained through a devolatilization step of separating volatile components such as unreacted monomers and solvents.

In this method, a rubbery polymer dissolved in a monomer is supplied to a first-stage polymerization vessel. At this time, the conversion of the first stage is preferably from 0.5 to 3 times the rubber concentration in the raw material. If it is 0.5 times or less, the heat removal load in the second and subsequent stages increases, and temperature control may be difficult. If it is three times or more, poor mixing is liable to occur due to high viscosity, and enlarged rubber particles are formed, which may cause a decrease in gloss. Further, the monomer and the polymerization initiator and the chain transfer agent used as required are supplied to the polymerization vessel at an arbitrary stage. In the final polymerization reactor, the conversion is preferably 65% by weight or more. If it is less than 65% by weight, the rubber particles are not stabilized, and in the subsequent devolatilization step, the rubber particles may be broken, resulting in a decrease in gloss. Furthermore, in the devolatilization step, usually at a reduced pressure of 50 mmHg or less, preferably 30 mmHg or less, usually 200 to 300 ° C, preferably 230 to 290 ° C,
More preferably, the volatile matter removal treatment is performed at a temperature in the range of 240 to 280 ° C. In particular, the temperature in this step affects the said relaxation time T _2. A preferred method for producing the rubber-modified styrene-based resin composition of the present invention is the continuous solution or bulk polymerization method, and the rubber-modified styrene-based resin composition obtained by this method is a diene-based rubbery polymer. Containing as rubber particles,
A method in which an aromatic monovinyl compound and vinyl cyanide or another copolymerizable monomer are added to a so-called emulsion-polymerized rubber latex for graft polymerization is not preferred.

In the polymerization method, as the molecular weight regulator used as desired, for example, α-methylstyrene dimer,
mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, 1-phenylbutene-2-fluorene, dipentene, chloroform, terpenes,
Halogen compounds and the like can be mentioned.

Further, as a polymerization initiator used as desired,
For example, peroxy ketals such as 1,1-bis (t-butylperoxy) cyclohexane and 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane,
Dicumyl peroxide, di-t-butyl peroxide,
Dialkyl peroxides such as 2,5-dimethyl-2,5-di (t-butylperoxy) hexane; diaryl peroxides such as benzoyl peroxide and m-toluoyl peroxide; peroxydicarbonates such as dimyristyl peroxydicarbonate; Organic peroxides such as peroxyesters such as t-butylperoxyisopropyl carbonate, ketone peroxides such as cyclohexanone peroxide, and hydroperoxides such as p-menthahydroperoxide can be exemplified.

In the composition of the present invention, the styrene resin and the diene rubber polymer are desirably contained in proportions of 70 to 95% by weight and 30 to 5% by weight, respectively. If the content of the rubbery polymer is less than 5% by weight, the effect of improving impact resistance is not sufficiently exhibited, and if it exceeds 30% by weight, gloss and fluidity tend to decrease, which is not preferable.

In the styrene resin composition of the present invention, the average particle diameter of the rubber dispersed particles is 0.08 to 1.00 μm, preferably 0.10
0.70.70μm circumference parameter is 0.1 ~ 2.5 (μm) ^-1・
(Wt%) ^-1, preferably, 0.3 to 2.0 ([mu] m) ^-1 · (wt%) ^-1 and the relaxation time T ₂ is 300～2000Myusec, preferably, should be in the range of 400~1800μsec . Here, the perimeter parameter refers to a relaxation of the outer perimeter of each rubber particle per unit area divided by the concentration of the diene component in the composition in a transmission electron microscope (TEM) photograph showing a rubber dispersion form. Value. Further, the relaxation time T ₂ are, using a pulsed NMR device, the hydrogen nucleus and measuring nuclear, measuring frequency 90 MHz, 90 ° under the conditions of pulse width 1.5～2.0Myusec, the Hahn-echo method at a temperature 30 ° C. (Hahn Echo
Method, 90 ° -τ-180 ° pulse method)
It is the spin-spin relaxation time of the rubber component in the composition.

If the average particle size of the rubber particles is less than 0.08 μm, the impact resistance is insufficient, and if it exceeds 1.00 μm, the gloss is reduced. You can also deviate circumferential length parameter the range, the impact resistance decreases when the relaxation time T ₂ is or outside the above range.

The particle size of said dispersed rubber particle, a peripheral length parameter, relaxation time T ₂ are, by varying the temperature of the stirring speed and devolatilizing tank various engager may be controlled.

The styrenic resin composition of the present invention, if desired, various additives conventionally used in styrenic resin compositions,
For example, lubricants, antioxidants, plasticizers, flame retardants, light stabilizers,
A coloring agent or the like may be added, and further, a filler such as a fiber reinforcing agent such as glass fiber or an inorganic filler may be filled. As the lubricant, for example, stearic acid, behenic acid, stearamide, methylene bis-stearamide, ethylene bis-stearamide and the like, as the antioxidant, for example, 2,6-di-t-butyl-4-methylphenol, Stearyl-β- (3,5-di-t-butyl-4
Hindered phenols such as -hydroxyphenyl) propionate and triethylene glycol-bis-3- (3-t-bityl-4-hydroxy-5-methylphenyl) propionate; and tri (2,4-di-t-butylphenyl) ) Phosphites, phosphorus-based compounds such as 4,4'-butylidenebis (3-methyl-6-t-butylphenyl-di-tridecyl) phosphite, and plasticizers such as mineral oil and polyethylene glycol. . Preferred examples of the flame retardant include a combination of an organic halogen-based flame retardant such as tetrabromobisphenol A, decabromodiphenyl oxide, and brominated polycarbonate with antimony oxide.

Further, the styrenic resin composition of the present invention may optionally contain, for example, ABS resin, polyvinyl chloride, styrene-acrylonitrile resin, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, nylon 6, nylon 11, nylon 12, and polyphenylene oxide. It can also be blended with a resin such as polyphenylene sulfide and used as a molding material.

[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.

In addition, each physical property of the composition was measured according to the method shown below.

(1) Melt index (MI) Determined in accordance with ISO R-1133.

(2) Gloss The gloss was determined in accordance with JIS K-7105.

(3) Surface impact strength (a) Test specimen shape: 75 x 75 x 3 mm, injection molded product (b) Testing machine: Rheometrics, drop weight testing machine (RDT5
000) (c) Measuring conditions: Dart total load 3.76kg Dart tip diameter 1/2 inch Specimen solid pedestal diameter 2 inches Dart hit point Specimen center Measured under the conditions of test speed 1.5m / sec or more.

(4) Average particle diameter The average particle diameter of the rubber-dispersed particles was determined by the following method.

The composition was stained with osmium tetroxide, and the thickness of the section was 0.1 μm with an ultramicrotome based on the ultrathin section method.
Is prepared, and a transmission electron microscope (TEM) photograph showing the dispersion state of the rubber particles in the ultrathin section is taken using a transmission electron microscope. For each rubber particle photographed in this TEM photograph, for a rubber particle having a diameter of 0.02 μm or more, the diameter of the rubber particle was measured by an image analyzer, and the area average particle diameter Ds (μm) was obtained by the following equation. And determine this as the average particle size.

(N _i is the number of rubber-like polymer particles having a diameter D _i of the rubber particles) The diameter of the rubber particles is the maximum length of the rubber particles (the maximum length is between any two points in one rubber particle). And the number N (Σn _i ) of the rubber particles to be measured is 3000 or more.

(5) Perimeter parameter Ci A TEM photograph showing the dispersion state of the rubber particles of the composition was obtained by the same method as described in the above-mentioned measurement of the average particle diameter, and in this photograph, the area A (μm ² )) The total length L (μm) of the outer circumference of each rubber particle present in
And the circumference density Cd is calculated from the following equation.

The number of rubber particles measured here is 3,000 or more.

On the other hand, the concentration (% by weight) of the diene component in the composition was ¹³ C
-Determined by NMR. That is, by a proton-gated decoupling method that eliminates the nuclear Overhauser effect (NOE), ¹³ C-NMR of a sample is performed using a 200 MHz NMR apparatus.
At a sample concentration of 16% by weight, solvent weight chloroform, temperature 23
° C, pulse width 6.9μsec (45 ゜), spectrum width 10,000Hz
The spectrum is obtained by measuring under the above measurement conditions. The concentration of the diene component in the sample (% by weight) is determined by comparing the integrated intensities of the specific signals of the styrene unit and the diene-based unit in the spectrum.

Next, a circumference parameter [(μm) ⁻¹ · (% by weight) ⁻¹ ] is determined from the circumference density Cd and the concentration of the diene component according to the following equation.

(6) using a relaxation time T ₂ pulse NMR apparatus, the hydrogen nuclei as measured nucleus, under conditions of a measurement frequency 90 MHz, 90 ° pulse width 1.5～2.0Myusec, temperature
By the Hahn-echo method at 30 ℃ (Hahn Echo Method, 90 °-tau-180 DEG pulse method), a spin of the rubber component in the composition - seeking spin relaxation time T _2, to do this the relaxation time T _2.

Example 1 At a feed rate of 5.8 per hour, the following mixture was continuously fed into a first polymerization vessel having a volume of 7.8 and having an squid-type stirrer.

Styrene-butadiene copolymer (manufactured by Zeon Corporation, ZLS-01, styrene content 22% by weight) 10.0% by weight Styrene 83.7% by weight Ethylbenzene 5.0% by weight n-dodecylmercaptan 0.01% by weight Irganox 1076 (manufactured by Ciba-Geigy, oxidation 0.09% by weight Mineral oil (manufactured by Idemitsu Kosan Co., Ltd.) 1.00% by weight Silicone oil (manufactured by Toray Silicone Co., Ltd.) 0.20% by weight The temperature of the first polymerization reactor was 140 ° C, and the styrene addition rate at the outlet was 21% by weight. there were. The polymer is then
11.0 second polymerization reactor with squid-type stirrer, followed by a capacity of 1
The solution was sent to a third polymerization vessel equipped with a 1.0 squid-type stirrer, and after continuing the polymerization, volatile components were removed in a vacuum chamber at 260 ° C. and 10 mmHg to obtain a pellet-shaped rubber-modified styrene-based composition. . The conversion of the third polymerization vessel was 72% by weight. The results are shown in Table 1. The number of rotations of the first polymerization tank was 10
0 rpm, stirring speed of the second polymerization tank was 150 rpm, and temperature was 145.
C., the number of revolutions of stirring in the third polymerization tank was 50 rpm, and the temperature was 160 ° C.

Examples 2 and 3 The same procedure was performed as in Example 1 except that the temperature of the vacuum chamber in Example 1 was changed to 280 ° C. (Example 2) and 245 ° C. (Example 3). Table 1 shows the results.

Example 4 Example 1 was carried out in the same manner as in Example 1 except that the rotation speeds of the first polymerization reactor and the second polymerization reactor were changed to 140 rpm and 180 rpm, respectively. Table 1 shows the results.

Example 5 In Example 4, the rubbery polymer was changed to polybutadiene (NF-35AS, manufactured by Asahi Kasei Corporation), and 1,1-
Same as Example 4 except that 0.03% by weight of bis (t-butylperoxy) -3,3,5-trimethylcyclohexane (based on the weight of the raw material mixture) was added, and the temperature of the first polymerization reactor was changed to 115 ° C. Was carried out. Table 1 shows the results. The conversion of the first polymerization reactor was 24 wt%, and the conversion of the third polymerization reactor was 76 wt%.

Example 6 In Example 1, styrene was changed to a combination of styrene and acrylonitrile (weight ratio: 75:25), and 0.03 of 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane was used as an initiator. The procedure was performed in the same manner as in Example 1 except that the weight of the raw material mixture (based on the weight of the raw material mixture) was added and the temperature of the first polymerization reactor was set at 115 ° C. The result is
It is shown in the table. The conversion rate of the first polymerization vessel was 28% by weight, and the conversion rate of the third polymerization vessel was 77% by weight.

Comparative Examples 1 and 2 The procedure of Example 1 was repeated, except that the temperature of the vacuum chamber was 295 ° C. (Comparative Example 1) and 225 ° C. (Comparative Example 2). Table 1 shows the results.

Comparative example 3 It carried out similarly to Example 4 except having used polybutadiene (made by Asahi Kasei Corporation, NF-35AS) as a rubber-like polymer. Table 1 shows the results.

Comparative Example 4 Example 1 was carried out in the same manner as in Example 1 except that the rotation speeds of the first polymerization reactor and the second polymerization reactor were set to 180 rpm and 220 rpm, respectively. Table 1 shows the results.

Reference Example 1 The procedure of Example 6 was repeated, except that the weight ratio of styrene: acrylonitrile was changed to 50:50. Table 1 shows the results.

[Effect of the Invention] The styrenic resin composition of the present invention is a rubber-modified styrenic resin composition comprising a diene-based rubbery polymer and a styrenic resin, having excellent gloss and high impact strength, particularly surface impact strength. For example, it is suitably used in the fields of OA equipment, home electric appliances, sheets and the like.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takashi Kanezaki 1-1, Anesaki Beach, Ichihara-shi, Chiba Idemitsu Oil Chemical Co., Ltd. (56) References JP-A-63-48317 (JP, A) JP-A-61 JP-A-143415 (JP, A) JP-A-59-179611 (JP, A) JP-A-2-34612 (JP, A) JP-A-2-208312 (JP, A)

Claims (1)

(57) [Claims] 1. A rubber-modified styrene resin composition comprising a diene rubber-like polymer and a styrene resin, wherein the diene rubber-like polymer has a styrene content of 20 to 50% by weight.
Styrene-butadiene block copolymer rubber or polybutadiene rubber, and the average particle diameter of the rubber-dispersed particles is 0.08 to 1.00 μm, and the circumference parameter is
0.1 to 2.5 (μm) ^-1 · (weight%) ^-1 and relaxation time T ₂ 300
A styrenic resin composition which satisfies the condition of 2000 μsec.