JPH085939B2 - Method for producing rubber-modified styrene resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a rubber-modified styrene resin composition. More specifically, the present invention is
The present invention relates to a method for producing a rubber-modified styrene resin composition having specific solid viscoelasticity and high surface impact strength.

[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 the rubber-like polymer, styrene is partially graft-polymerized to the rubber-like polymer, and the balance of styrene becomes polystyrene. Then, it is industrially carried out to obtain a so-called rubber-modified polystyrene resin composition in which a substantially rubber-like polymer / styrene graft copolymer and polystyrene are mixed.

The impact resistance of such a rubber-modified polystyrene resin has been conventionally judged by the Izod impact strength of a compression-molded test piece, but the surface impact strength is also important as the practical impact strength of the molded product. It has been found that, in recent years, in terms of impact resistance, not only Izod impact strength but also surface impact strength has been required.

By the way, in a rubber-modified styrene-based resin composition, it is known that the larger the damping peak area for the loss elastic modulus E ″ of the rubber component obtained from the solid viscoelasticity measurement, the higher the Izod impact strength. The relationship between the data and the surface impact strength has never been known so far.

For example, as a technique for improving the surface impact strength of impact-resistant polystyrene, there are a method for producing impact-resistant polystyrene (Japanese Patent Publication No. 53-44188), a method for producing styrene-based resin (Japanese Patent Publication No. 55-30525), and the like. Although disclosed, these methods do not describe the relationship between surface impact strength and solid viscoelasticity.

[Problems to be Solved by the Invention] Under such circumstances, the present invention uses a rubber-modified styrene resin composition having a high surface impact strength by using a specific parameter relating to solid viscoelasticity and defining it. The purpose of the invention is to provide a method for manufacturing a product.

[Means for Solving the Problems] As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that solid viscoelasticity data obtained by measuring at a specific frequency causes loss in a certain temperature range. It was found that the rubber-modified styrene-based resin composition having a maximum damping temperature of the damping peak with respect to the elastic modulus E ″ and having a damping peak ratio defined by a specific formula is a certain value or more has a high surface impact strength, The present invention has been completed based on this finding.

That is, in the present invention, in the presence of a rubbery polymer, an aromatic monovinyl compound or a mixture of an aromatic monovinyl compound and a monomer copolymerizable therewith is polymerized by a bulk-suspension two-stage polymerization method. In producing the rubber-modified styrene-based resin composition, 30 to 5% by weight of the rubber-like polymer,
An aromatic monovinyl compound or a mixture of an aromatic monovinyl compound and a copolymerizable monomer is used in a proportion of 70 to 95% by weight, and the bulk polymerization in the first stage is heated stepwise to a temperature of 70 to 150 ° C. When the solid viscoelasticity of the composition is measured at a frequency of 100 Hz, the composition has a maximum damping temperature of a damping peak P _M regarding a loss elastic modulus E ″ in a temperature range of 0 to 50 ° C., and formula (However, S _M100 and S _R100 are each a measurement frequency of 100 Hz.
Is a height of a damping peak P _M and a damping peak with respect to a loss elastic modulus E ″ of a rubber portion), and a rubber-modified styrenic resin composition having a damping peak ratio R _M100 of 0.1 or more. It provides a method.

 Hereinafter, the present invention will be described in detail.

In the method of the present invention, in the presence of a rubbery polymer,
An aromatic monovinyl compound or a mixture of an aromatic monovinyl compound and a monomer copolymerizable therewith is polymerized by a bulk-suspension two-stage polymerization method.

That is, in the method of the present invention, an aromatic monovinyl compound alone or a mixture of an aromatic monovinyl compound and a monomer capable of copolymerizing the aromatic monovinyl compound is used as the styrene-based monomer.

Examples of the aromatic monovinyl compound used in the method of the present invention include styrene, α-methylstyrene, α-ethylstyrene, α-alkyl-substituted styrene such as α-methyl-p-methylstyrene, 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, as well as p-hydroxystyrene, o-methoxystyrene, vinylnaphthalene, and the like can be mentioned. In particular, styrene and α-methylstyrene are preferable. These aromatic monovinyl compounds may be used alone or in combination of two or more.

Further, as the monomer copolymerizable with the aromatic monovinyl compound, for example, acrylonitrile, methacrylonitrile, fumaronitrile, maleonitrile, vinyl cyanide such as α-chloroacrylonitrile, methyl methacrylate, methyl acrylate, methacrylic acid, Acrylic acid,
Examples thereof include maleic anhydride, phenylmaleimide, etc. Among these, vinyl cyanide, particularly acrylonitrile, is preferable. These monomers may be used alone or in combination of two or more. When vinyl cyanide is used as the monomer copolymerizable with the aromatic monovinyl compound, the ratio of the aromatic mol vinyl compound and the vinyl cyanide is based on the weight, the former: the latter = 10.
It is preferable to use it in a ratio of 0: 0 to 55:45.
That is, it is preferable to use the vinyl cyanide in an amount of 45% by weight or less. When the proportion of vinyl cyanide exceeds 45% by weight, the thermal stability and fluidity are deteriorated, which is not preferable.

The type of the rubber-like polymer used in the method of the present invention is not particularly limited, and those conventionally used in rubber-modified styrene-based resin compositions such as natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene can be used. Copolymer rubber, styrene-isoprene copolymer rubber,
Synthetic rubbers such as butyl rubber and ethylene-propylene copolymer rubber, and graft copolymer rubbers of these rubbers and styrene are used. These rubber-like polymers may be used alone or in combination of two or more.

In the method of the present invention, in the presence of a rubbery polymer,
An aromatic monovinyl compound as described above or a mixture of an aromatic monovinyl compound and a monomer copolymerizable therewith,
Polymerization is carried out by a bulk-suspension two-stage polymerization method.

Next, one example of a preferred method for producing the resin composition of the present invention by the bulk-suspension two-stage polymerization method will be described. First, an aromatic monovinyl compound or an aromatic monovinyl compound and a monomer copolymerizable with the aromatic monovinyl compound The rubbery polymer is added to the mixture and heated to dissolve it, if necessary. It is preferable that this dissolution be performed as uniformly as possible.

Next, to this solution, a molecular weight regulator (chain transfer agent) such as alkyl mercaptan and a polymerization initiator such as an organic peroxide used as needed are added, and the mixture is heated stepwise to a temperature of 70 to 150 ° C. While stirring, prepolymerization is performed by the bulk polymerization method until the degree of polymerization reaches 10 to 60%. In this pre-polymerization step, the rubbery polymer is dispersed into particles by stirring.

Next, the preliminarily polymerized solution is suspended in an aqueous phase using tricalcium phosphate, polypinyl alcohol or the like as a suspending agent, and usually suspension polymerization (main polymerization) is carried out until the degree of polymerization approaches 100%. If necessary, after this main polymerization step,
Further heating may be continued.

Examples of the molecular weight regulator include α-methylstyrene dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, 1-phenylbutene-2-fluorene,
Examples thereof include mercaptans such as dipentene and chloroform, terpenes, halogen compounds and the like.

Further, as the polymerization initiator used as desired,
For example, peroxyketals such as 1,1-bis (t-butylperoxy) cyclohexane and 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, dicumyl peroxide, di-t-butyl peroxide, 2,
Dialkyl peroxides such as 5-dimethyl-2,5-di (t-butylperoxy) hexane, benzoyl peroxide, diaryl peroxides such as m-toluoyl peroxide, peroxydicarbonates such as dimyristyl peroxydicarbonate, t- Examples thereof include peroxyesters such as butylperoxyisopropyl carbonate, ketone peroxides such as cyclohexanone peroxide, and organic peroxides such as hydroperoxides such as p-menthahydroperoxide.

In the method of the present invention, 70 to 95 wt% of the aromatic monovinyl compound or the mixture of the aromatic monovinyl compound and the monomer copolymerizable with the above-mentioned rubber polymer is used in an amount of 30 to 5 wt%. Used in proportion. If the amount of the rubber-like polymer is less than 5% by weight, the effect of improving impact resistance is not sufficiently exerted, and if it exceeds 30% by weight, gloss and fluidity tend to be deteriorated, which is not preferable.

In the method of the present invention, when the solid viscoelasticity of the obtained rubber-modified styrenic resin composition is measured at a frequency of 100 Hz, the maximum attenuation temperature of the attenuation peak P _M regarding the loss elastic modulus E ″ is in the temperature range of 0 to 50 ° C. And has the formula (However, S _M100 and S _R100 are each a measurement frequency of 100 Hz.
It is necessary that the damping peak ratio R _M100 defined by the height of the damping peak P _M and the damping peak P _R regarding the loss elastic modulus E ″ of the rubber portion is 0.1 or more. In the elasticity measurement, the rubber-modified styrene resin composition satisfying such requirements has high surface impact strength.

Next, the requirements for this solid viscoelasticity measurement will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing the solid viscoelasticity of an example of a rubber-modified styrenic resin composition obtained by the method of the present invention, that is, frequencies of 10 Hz and 100 Hz.
2 is a graph showing the temperature dispersion of loss elastic modulus E ″, storage elastic modulus E ′, and loss tangent tan δ when measured in FIG. 2, and FIG. 2 shows the loss elastic modulus E obtained by measuring at a frequency of 100 Hz in FIG. It is a partial enlarged view of temperature dispersion of "". In the method of the present invention, the rubber-modified styrene resin composition is
As shown in the figure, it is necessary to have the maximum damping temperature of the damping peak P _M regarding the loss elastic modulus E ″ in the temperature range of 0 to 50 ° C.

Figure 3 shows the formula FIG. 4 is an explanatory diagram for _obtaining a damping peak ratio R _M100 defined by, where L _o is a curve of E ″ (t at a temperature of −100 ° C. or lower).
consisting value of E "at anδ = 0), BL100 is a straight line extrapolated L _o to the high temperature side, a baseline for calculating the S _M100 and S _R100. Moreover, E _M is the attenuation peak P loss modulus values of _M, T _M is the maximum attenuation temperature of the attenuation peak P _M, T _R is the maximum attenuation temperature of the attenuation peak P _R of the rubber portion, L _M is BL in T _M
Loss modulus value of 100, the loss modulus value E _R is P _R, L _R is a loss modulus value of BL100 in T _R, the S _M100 and S
_R100 can be _calculated by the following equation. The viscoelasticity measurement frequency is 100 Hz.

S _M100 = E _M −L _M (II) S _R100 = E _R −L _R (III) Calculated according to the above formula (I) from S _M100 and S _R100 thus obtained. R _M100 needs to be 0.1 or more in the method of the present invention.

In the method of the present invention, if desired, various additives conventionally used in styrene resin compositions such as lubricants, antioxidants, plasticizers, flame retardants, light stabilizers, and colorants are added. Alternatively, a fiber reinforcing agent such as glass fiber or a filler such as an inorganic filler may be added. Examples of the lubricant include stearic acid, behenic acid, stearamide, methylenebisstearamide, ethylenebisstearamide, and the like, and examples of the antioxidant include 2,6-di-t-butyl-4-methylphenol, Hinders such as stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and triethyleneglycol-bis-3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate Phosphorus such as dephenol and tri (2,4-di-t-butylphenyl) phosphite and 4,4'-butylidenebis (3-methyl-6-t-butylphenyl-di-tridecyl) phosphite As the plasticizer, for example, mineral oil or polyethylene glycol is used. Preferred examples of the flame retardant include a combination of an organic halogen-based flame retardant such as tetrabromobisphenol A, decabromodiphenyl oxide, brominated polycarbonate and antimony oxide, and the like.

Further, in the method of the present invention, if desired, for example, ABS resin, polyvinyl chloride, styrene-acrylonitrile resin, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, nylon 6, nylon 11, nylon 12, polyphenylene oxide, polyphenylene sulfide, etc. It can also be blended with the above resin and used as a molding material.

EXAMPLES Next, the present invention will be described in more detail by way of 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) P _M maximum attenuation temperature, attenuation peak ratio R _{M100 Pelletized} resin composition is press molded into a sheet of 120 × 120 × 1 ^t mm at 200 ° C., and a size of 40 × 40 mm is obtained from this sheet. After cutting out the sheet, hold it in the oven at 105 ° C for 16 hours, and let it cool naturally in the oven, then width 4 mm, length 4
A 0 mm test piece was cut with a sharp knife.

Next, regarding the solid viscoelasticity of this test piece, using a fully automatic solid viscoelasticity measuring device (viscoelasticity spectrum meter, VES-F-III type) manufactured by Iwamoto Seisakusho under the following measurement conditions, a constant vibration strain test was conducted. The temperature dispersion of loss elastic modulus E ″, storage elastic modulus E ′, and loss tangent tan δ was determined.

・ Measurement conditions Measurement frequency: 10Hz, 100Hz Dynamic displacement: 0.02mm Distance between initial chucks: 20mm Initial load: 1,500g Temperature measurement range: −150 to + 100 ℃ Temperature rising rate: 2 ℃ / min Next, measurement frequency 100Hz From the solid viscoelasticity data in the case of, the presence or absence of the maximum damping temperature of the damping peak P _M regarding the loss elastic modulus E ″ is confirmed in the temperature range of 0 to 50 ° C. as shown in FIG. Attenuation peak ratio R
I asked for _M100 .

(2) Surface impact strength An injection-molded product with a width of 70 mm, a length of 270 mm, and a thickness of 3 mm was used, and the impact point was a 125 mm from the gate opening on the one side of the test piece, at the center point in the width direction, and a drop weight test manufactured by Rheometrics. Using a crosspiece (RDT5000), a surface impact test was conducted under the following measurement conditions to determine the surface impact strength.

・ Measurement conditions Dirt total load: 3.76 kg Dirt tip shape: 1/2 inch Specimen holder pedestal diameter: 2 inches Test speed: 3.5 m / s Breaking energy: DIN53443, "Damaging energy" specified in Part 2 is used I was there.

(3) Melt index (MI) Obtained according to JIS K-7210.

(4) Flexural modulus It was determined according to JIS K-7203.

Example 1 A styrene-butadiene block copolymer [ZLS-01] 300 manufactured by Nippon Zeon Co., Ltd. was placed in an autoclave having an internal volume of 5 l.
g, 3000 g of styrene and 1 g of n-dodecyl mercaptan as a chain transfer agent were added, and the mixture was stirred at 200 rpm for 2 hours at 90 ° C.
The reaction was performed at 110 ° C. for 1 hour and 140 ° C. for 1 hour.

Then, in a 10 l autoclave, the reaction mixture 3
Add 000 g, 3000 g of water, 10 g of polyvinyl alcohol as a suspension stabilizer, 6 g of benzoyl peroxide, and 6 g of dicumyl peroxide, and stir at 500 rpm and raise the temperature from 60 ° C to 140 ° C at a heating rate of 20 ° C / hour. Warm and 4 more
After reacting for a period of time, rubber-modified polystyrene beads were obtained. The obtained beads are pelletized by a single-screw extruder at 220 ° C., and then molded to prepare a test piece for physical property test,
Each physical property was measured. The results are shown in Table 1. Moreover, the measurement results of solid viscoelasticity are shown in FIG. 1 and FIG.

Example 2 The procedure of Example 1 was repeated, except that the amount of dicumyl peroxide was changed to 3 g. The results are shown in Table 1.

Example 3 In Example 1, instead of styrene, styrene /
Example 1 was carried out in the same manner as in Example 1 except that a combination of acrylonitrile (weight ratio 60/40) was used. The result is first
Shown in the table.

Example 4 In Example 1, instead of styrene, styrene /
Example 1 was carried out in the same manner as in Example 1 except that a combination of acrylonitrile (weight ratio 95/5) was used. The results are shown in Table 1.

Comparative Example 1 In Example 1, the reaction conditions for the bulk polymerization were 140 ° C. and 3
The same procedure as in Example 1 was carried out except that the time was set. The results are shown in Table 1.

Comparative Example 2 In Example 1, instead of the styrene-butadiene block copolymer, polybutadiene [Asahi Kasei Co., Ltd.,
NF35AS] and the reaction conditions for bulk polymerization are 140 ° C and 3
The same procedure as in Example 1 was carried out except that the time was set. The results are shown in Table 1.

Reference Example 1 In Example 1, instead of styrene, styrene /
It was carried out in the same manner as in Example 1 using a combination of acrylonitrile (weight ratio 50/50), but molding was impossible due to insufficient fluidity.

[Effects of the Invention] According to the present invention, a rubber-modified styrene resin composition having a high surface impact strength can be provided by using a specific parameter relating to solid viscoelasticity and defining it, and also the surface impact. It is possible to easily determine whether or not the styrene resin composition has a high surface impact strength without conducting a test.

The rubber-modified styrene-based resin composition obtained by the method of the present invention is suitably used, for example, as a component material for home electric appliances and OA equipment, or various sheet materials.

[Brief description of drawings]

FIG. 1 is a graph showing temperature dispersion of loss elastic modulus E ″, storage elastic modulus E ′, and loss tangent tan δ in solid viscoelasticity measurement of an example of a styrene resin composition obtained by the method of the present invention. The drawing is a partially enlarged view of the temperature dispersion of the loss elastic modulus E ″ (when the measurement frequency is 100 Hz) in FIG. 1, and FIG. 3 is an explanatory view for _{obtaining the} attenuation peak ratio R _M100 .

Claims (2)

[Claims] 1. A polymerization of an aromatic monovinyl compound or a mixture of an aromatic monovinyl compound and a monomer copolymerizable therewith in the presence of a rubbery polymer by a bulk-suspension two-stage polymerization method. In producing the rubber-modified styrenic resin composition, 70 to 95 parts by weight of an aromatic monovinyl compound or a mixture of an aromatic monovinyl compound and a monomer copolymerizable with 30 to 5% by weight of a rubber-like polymer is used. 0% when the solid viscoelasticity of the composition is measured at a frequency of 100 Hz, which is characterized in that it is used in a weight% ratio and the bulk polymerization in the first stage is carried out while heating stepwise to a temperature of 70 to 150 ° C. Has a maximum damping temperature of a damping peak P _M with respect to loss elastic modulus E ″ in a temperature range of up to 50 ° C. (However, S _M100 and S _R100 are each a measurement frequency of 100 Hz.
Is a height of a damping peak P _M and a damping peak with respect to a loss elastic modulus E ″ of a rubber portion), and a rubber-modified styrenic resin composition having a damping peak ratio R _M100 of 0.1 or more. Method. 2. A monomer copolymerizable with an aromatic monovinyl compound is vinyl cyanide, and the ratio of the aromatic monovinyl compound and the vinyl cyanide is based on the weight of the former: the latter = 100: 0. The method for producing a rubber-modified styrenic resin composition according to claim 1, wherein the ratio is from 55 to 45.