JPH0768319B2 - Styrene resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a styrenic resin, and more specifically, it has excellent gloss and impact resistance, and is excellent in its balance, so that it can be used in home appliances, OA equipment, and various sheets. The present invention relates to a rubber-modified polystyrene resin that can be suitably used in fields and the like.

[Prior Art and Problems Thereof] Conventionally, in order to improve the brittleness of polystyrene polymer, a method of mechanically mixing unvulcanized rubber and polystyrene, or a method of graft polymerization in a polymerization system has been applied. It was However, in recent fields where impact resistance and surface gloss are required, these methods have not been sufficient.

For example, in the methods described in JP-A-50-157493, JP-B-54-19031 and JP-B-54-37906, a styrene-butadiene block copolymer having randomness is applied to a polymerization reaction. However, in this case, there is a problem that the gloss of the resin composition obtained is not sufficient, and in the method described in JP-A-61-143415,
Although a complete block copolymer is used, the block polystyrene has a low molecular weight of 1,000 to 10,000, so that the obtained resin composition has a low gloss.

The present invention has been made based on the above circumstances, and an object thereof is to have a specific rubber particle size, a specific matrix molecular weight, and a gloss that is several times superior to conventional impact-resistant polystyrene. It is to provide a styrene-based resin that has a high impact resistance, is extremely advantageous in practical use, and has an excellent balance between them.

[Means for Solving Problems] As a result of intensive studies, the present inventors have obtained styrenes and a complete block type styrene-butadiene block copolymer by copolymerizing at a specific ratio, Moreover, it has been found that a styrene resin having a specific rubber particle diameter and a specific matrix molecular weight achieves the object of the present invention, and the present invention has been completed based on this finding.

That is, the present invention is (A) styrenes 92 to 60 wt%
And (B) a complete block type styrene-butadiene block copolymer of 8 to 40% by weight, wherein the (B) complete block type styrene-butadiene block copolymer is used as a repeating unit. The content of styrenes
10 to 50% by weight, the molecular weight is in the range of 80,000 to 300,000, the weight average molecular weight of the block polystyrenes part is 15,000 to 150,000, and the diameter of the rubber particles is 0.1 to 1.8μ.
m and the molecular weight of the matrix is 100,000 to 300,000.

The above-mentioned Japanese Patent Application Laid-Open No. 50-157493 introduced in the section of the prior art.
According to the description of the gazette, a specific styrene-butadiene random copolymer having a gradually decreasing composition in which the styrene content is continuously reduced along the polymer chain and styrene have excellent impact resistance and weldability. Although it is possible to obtain an impact-resistant polystyrene composition having an appearance, the impact-resistant polystyrene obtained from a complete block copolymer of styrene and butadiene has a low Izod impact strength. From such a fact, it is surprising that a styrene resin excellent in both impact resistance and gloss in a well-balanced manner can be obtained from the complete block type styrene-butadiene block copolymer as in the present invention. is there.

Further, JP-A-61-143415 discloses a polystyrene resin having a block styrene portion having a number average molecular weight of 1,000 to 10,000 and having excellent gloss and impact resistance. In the publication, when the number average molecular weight of the block styrene portion exceeds 10,000, it is disclosed that the impact resistance of the polystyrene-based resin is significantly reduced. Molecular weight 15,000-150,000
It is unexpected that it is possible to obtain an impact resistant resin excellent in both gloss and impact resistance from the specific full block type styrene-butadiene block copolymer.

As described above, the present invention, which is unexpected from the conventional technique, will be described in detail below.

— (A) Styrenes— The styrenes of the component (A) are monomers copolymerizable with styrene (A ₁ ) and styrene, and form an impact-resistant styrene resin by copolymerization with styrene. Part of the styrene repeating unit in the styrene polymer is a monomer (A ₂ ) capable of forming a styrene copolymer in which a repeating unit other than the styrene is substituted.

However, the monomer (A ₂ ) other than styrene is used in the range of 50% by weight or less, preferably 40% by weight or less, based on the total amount of monomers containing styrene.

Examples of the monomer (A ₂ ) other than styrene include, for example,
α-Methylstyrene, vinyltoluene, vinylethylbenzene, vinylxylene, vinylnaphthalene and other monovinylaromatic hydrocarbons (A _2a ), acrylonitrile, methyl methacrylate, methyl acrylate, acrylic acid, methacrylic acid, maleic anhydride, phenylmaleimide Etc. can be mentioned, and these 1 type (s) or 2 or more types can be used together with styrene.

— (B) Complete Block Type Styrene-Butadiene Block Copolymer— The complete block type styrene-butadiene block copolymer of component (B) (hereinafter referred to as SB block copolymer (B) or simply (B)). May be referred to as "). A complete block type styrene-1,3-butadiene block copolymer (hereinafter may be simply referred to as SB block copolymer (B ₁ ) or simply (B ₁ )." , The SB block copolymer
(B ₁ ) wherein one part of the styrene repeating unit in (B ₁ ) is replaced with a repeating unit of monovinyl aromatic hydrocarbon (B _2a ) copolymerizable with styrene (B ₂ ), 1,3-in the (B ₁ ) A part of the butadiene repeating unit replaced with a diolefin ( _B3a ) repeating unit other than 1,3-butadiene
(B ₃ ), a part of the styrene repeating unit in (B ₁ ) and
Some of the 1,3-butadiene repeating units are each
The (B _2a ) repeating unit and the above (B _3a ) repeating unit replaced with (B ₄ ) can be used.

However, the amount of the (B _2a ) repeating unit in the above (B ₂ ) and (B ₄ ) and the amount of the (B _3a ) repeating unit in the above (B ₃ ) and (B ₄ ) is styrene, respectively. 50% by weight based on the total weight of monovinyl aromatic hydrocarbon repeating units containing and conjugated diolefin repeating units containing 1,3-butadiene
The amount used below is preferably 40% by weight or less.

Incidentally, monovinyl aromatic hydrocarbons other than styrene (B
_As specific examples of _2a ), the same as the above-mentioned (A _2a ) can be mentioned, and one kind or two or more kinds thereof can be used.

Examples of diolefins other than 1,3-butadiene include isoprene, 1,3-pentadiene,
2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-
Butadiene, 2,3-diethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, 2,3-diphenyl-1,3-butadiene, etc. may be mentioned, and one of these or
Two or more types can be used.

The completely block-type styrene-butadiene block copolymer (B) in the present invention has a repeating unit content of the styrenes [that is, styrene and monovinyl aromatic hydrocarbon (B _2a ) other than styrene]. The amount of repeating units used and the amount of repeating units used of the 1,3-butadienes (that is, 1,3-butadiene and other diolefins other than 1,3-butadiene (B _3a )) When the total amount is 100% by weight, 10-50% by weight,
Preferably used is within the range of 12 to 48% by weight.

If the content of this styrene repeating unit is less than 10% by weight, the gloss of the obtained resin becomes low, while 50% by weight
If it exceeds, the impact resistance will decrease.

Further, the above (B) according to the present invention is a complete block type having substantially no random component,
If a component having a significant random component is used as the component (B), the resulting resin will have insufficient gloss.

Further, (B) has an average molecular weight of 80,000 to 30.
0,000, preferably in the range of 90,000 to 280,000, the molecular weight is less than 80,000, the resulting resin has low impact resistance, while, if it exceeds 300,000, the fluidity during molding is low. Will be insufficient.

Further, the (B) has a weight average molecular weight of the block portion formed by the styrenes of 15,000 to 150,000,
Preferably, it is in the range of 20,000 to 140,000, but the weight average molecular weight of the block portion is less than 15,000, the resulting resin has insufficient gloss, while 15
If it exceeds 0,000, the impact resistance becomes insufficient.

In the present invention, the complete block type styrene-butadiene-based block copolymer (B) is the SB block copolymer (B ₁ ).

This SB block copolymer (B ₁ ) can be produced, for example, as follows.

For example, JP-A-50-157493, in the presence of the organolithium catalyst described in JP-B-54-19031, hexane,
In an inert hydrocarbon solvent such as heptane or benzene,
The SB block copolymer (B ₁ ) can be produced according to the method of polymerizing styrene and 1,3-butadiene.

That is, 1,3-butadiene is polymerized in the above-mentioned inert hydrocarbon in the presence of the above-mentioned organic lithium, and when the whole amount of this 1,3-butadiene is polymerized, a predetermined amount of styrene is added to the polymerization system. The desired SB block copolymer (B ₁ ) can be obtained by polymerizing styrene in a block shape on the active terminal of the already produced polybutadiene.

As specific examples of the organic lithium-based catalyst, propyllithium, n-butyllithium, sec-butyllithium, amyllithium, dilithiobutane, naphthyllithium, 1,4-dilithiobenzene and the like are used.

—Styrene Resin— (Copolymerization Reaction) The styrene resin in the present invention is obtained by copolymerizing the (A) styrenes and (B) the complete block type styrene-butadiene block copolymer. is there.

In carrying out the copolymerization, the amount of the styrenes used as the component (A) is the amount of the component (A) used and the amount of the complete block styrene-butadiene block copolymer used as the component (B). And the total of 100% by weight, 92
-60% by weight, preferably 91-62% by weight.

When the amount used exceeds 92% by weight, the impact resistance of the resulting styrene resin molded article decreases, while when it is less than 60% by weight, the gloss decreases and the fluidity during molding decreases. .

The copolymerization of the component (B) and the component (A) can be carried out by a known polymerization method or the like, as in the polymerization reaction used for obtaining the component (B).

Examples of such known polymerization methods include an emulsion polymerization method, a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and a combined multi-stage polymerization method such as a bulk-suspension two-stage polymerization method.

The following is an example of a general method for producing the resin of the present invention by the bulk-suspension two-stage polymerization method.

First, a complete block type styrene-butadiene-based copolymer, which is a rubber-like elastic material, is added to styrene, and if necessary, heated to dissolve.

It is preferable that this dissolution be performed as uniformly as possible.

Next, in the presence of a molecular weight regulator (or a chain transfer agent) such as alkyl mercaptan and a polymerization catalyst (or a polymerization initiator) such as an organic peroxide, which is optionally used,
The degree of polymerization of styrene is 10 ~ 6 while stirring at 150 ℃.
Preliminary polymerization is performed by the bulk polymerization method until it reaches 0%. In this prepolymerization step, the rubber-like elastic material is dispersed into particles by stirring.

After the completion of the above prepolymerization step, suspension polymerization is carried out by suspending in a water phase using tribasic calcium phosphate, polyvinyl alcohol or the like as a suspending agent. Usually, polymerization (main polymerization) is carried out until the degree of polymerization approaches 100%. If necessary, heating may be further continued after this main polymerization step.

Next, the obtained slurry is dehydrated, the beads are separated and dried, and then pelletized by a conventional method to obtain a resin composition. When carrying out the polymerization, additives such as a polymerization initiator and an antioxidant which are appropriately used can be used as described above.

Examples of the organic peroxide include peroxyketals such as 1,1-bis (t-butylperoxy) cyclohexane and 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane; Dialkyl peroxides such as -t-butyl peroxide and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, benzoyl peroxide, dialperoxides such as m-toluoyl peroxide, dimyristyl peroxydicarbonate, etc. Peroxydicarbonates, peroxyesters such as t-butylperoxyisopropyl carbonate, ketone peroxides such as cyclohexanone peroxide, and hydroperoxides such as p-menthahydroperoxide.

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

(Resin) The styrene resin in the present invention can be obtained as described above, and the rubber-like elastic material is dispersed as particles in the hard phase of the styrene polymer in the styrene resin.

In the styrene resin of the present invention, the particle size of the rubber-like elastic body (hereinafter sometimes referred to as rubber particle size) is 0.1 to.
It is a rubber-modified styrenic resin having a range of 1.8 μm, preferably 0.2 to 1.6 μm, and a matrix molecular weight of 100,000 to 300,000, preferably 130,000 to 280,000. The molded product made by molding this resin has excellent gloss and impact resistance, and the balance between them is especially high.
It is significantly superior to PS (high impact polystyrene).

If the rubber particle size is less than 0.1 μm, the impact resistance of the styrene resin molding will be insufficient, while 1.8 μm
If it exceeds, the luster becomes low.

Further, if the matrix molecular weight is less than 100,000, the impact resistance of the styrene resin molded article becomes insufficient,
On the other hand, if it exceeds 300,000, the fluidity during molding becomes insufficient.

Incidentally, the definition and measuring method of the rubber particle diameter and the matrix molecular weight are shown in the following [Example].

Incidentally, the styrene resin according to the present invention, if desired,
Various additives such as known additives, for example, stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, ethylene bis stearamide, organic polysiloxane, mineral oil, etc., and as an antioxidant, For example, hindered phenols, hindered bisphenols, hindered trisphenols, etc., and, for example, 2,6-di-t-
Butyl-4-methylphenol, stearyl-β- (3,
5-di-t-butyl-4-hydroxyphenyl) propionate, triethylene glycol-bis-3- (3-
t-butyl-4-hydroxy-5-methylphenyl) propionate or the like, or a phosphorus compound such as tri (2,4-di-t-butylphenyl) phosphite,
4,4'-butylidene-bis- (3-methyl-6-t-butylphenyl-di-tridecyl) phosphite or the like can be added, and if necessary, a stabilizer, a dye, a pigment or a filler. Lubricants, release agents, plasticizers, antistatic agents, etc. can also be added.

If desired, the styrene resin of the present invention may be used by blending with another polymer such as polyphenylene ether.

The styrenic resin of the present invention thus obtained is HI
It has excellent basic properties as PS, excellent gloss and impact resistance, and particularly excellent balance, and can be suitably used for home appliances, OA equipment, various sheet fields and the like.

[Examples] Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

The polymer composition, various physical properties, measurement methods and definitions are as follows. The symbol SB represents styrene-butadiene, and PS represents polystyrene styrenes.

(1) Rubber particle diameter: After dyeing with osmic acid, a photograph was taken with a transmission electron microscope, and the particle diameter of about 1000 particles was measured.

Next, the area average diameter was calculated based on the following formula, and this was made the rubber particle diameter.

Area average diameter = Σdi ³ / Σdi ² (however, di represents the particle diameter of the i-th particle.) (2) Matrix molecular weight (Mw): Centrifuged to remove the gel component after dissolving the resin in methyl ethyl ketone Then, the supernatant containing the matrix component was dried. Then, a 0.2 wt% solution of the matrix component was prepared using tetrahydrofuran as a solvent, and using GPC150 C manufactured by Waters Co., the weight average molecular weight (Mw),
It was calculated in terms of polystyrene.

(3) Styrene content of SB block copolymer: Measured at ¹³ C: 50.1 MHz at room temperature using chloroform as a solvent with a JNM-FX200 nuclear magnetic resonance apparatus manufactured by JEOL.

(4) Confirmation that there is no random component in the SB block copolymer: After dissolving in chloroform, blowing ozone gas, then reducing with lithium aluminum hydride to decompose the butadiene component, and using tetrahydrofuran as a solvent, manufactured by Waters It was confirmed by GPC that no styrene chain based on random components was detected.

(5) Molecular Weight (Mw) of SB Block Copolymer: A 0.2% by weight solution of the SB block copolymer was calculated in terms of polystyrene using GPC manufactured by Waters Co., Ltd. using tetrahydrofuran as a solvent.

(6) Molecular weight (Mw) of block PS part: After dissolving in chloroform, blowing ozone gas, then reducing with acetic acid / zinc to decompose the butadiene component, and using tetrahydrofuran as a solvent and GPC manufactured by Waters Co., Ltd., It was calculated in terms of polystyrene.

(7) Izod impact value: Based on JIS-K-7110 (23 ° C notched).

(8) Gloss: Conforms to JIS-Z-8741.

(9) Flexural modulus: According to ASTM D 790.

(10) Melt index: Conforms to JSO R 1133.

(Example 1) Production Example of Complete Block Type Styrene-Butadiene Block Copolymer (1a) To a 20% n-hexane solution containing 75 parts by weight of 1,3-butadiene, 0.07 part by weight of n-butyllithium was added. It was added as a wt% n-hexane solution and polymerized at 80 ° C. for 2 hours. 1,3
After the total amount of butadiene has been polymerized, 25 parts by weight of styrene is added to polybutadiene having a polymerization active terminal, and the mixture is further polymerized for 2 hours to obtain a block copolymer solution consisting of a 1,3-butadiene polymer block and a styrene polymer block. Got To the copolymer solution, 1 part by weight of di-tert-butyl-p-cresol was added as a stabilizer per 100 parts by weight of the copolymer, the solvent was distilled off by heating, and the desired copolymer was isolated.

No random component was detected in the obtained SB block copolymer, the styrene content was 25% by weight, the molecular weight was 180,000,
The molecular weight of block polystyrene was 60,000.

Method for producing styrene resin (1b) In an autoclave having an internal volume of 5 l, 800 g of the SB block copolymer obtained in the above Production Example (1a), 2,400 g of styrene and 0.96 g of n-dodecyl mercaptan (300 pp as a chain transfer agent)
m) was added and the reaction was carried out at 140 ° C. for 4 hours while stirring at 300 rpm. Then, in a 10 l autoclave, 3,000 g of the obtained reaction mixture, 3,000 g of water, 10 g of polyvinyl alcohol as a suspension stabilizer, 6 g of benzoyl peroxide and 3 g of dicumyl peroxide as a polymerization initiator, and 500 r
140 ° C at a heating rate of 80 ° C to 30 ° C / hour while stirring at pm
The temperature was raised to 0 ° C., and the reaction was further continued for 4 hours to obtain rubber-modified polystyrene beads.

The obtained beads were pelletized with a uniaxial extrudate at 220 ° C. and then molded.

The results are shown in Table 1.

(Examples 2 to 4 and Comparative Examples 1 to 3) In Example 1, except that the rotation speed and the amount of n-dodecyl mercaptan used were changed as shown in Table 1 to change the rubber particle diameter and the molecular weight of the matrix. Was carried out similarly.

The results are shown in Table 1.

(Examples 5 and 6 and Comparative Examples 4 and 5) In Example 1, the amount of the SB block copolymer used was changed to the first.
It carried out similarly except having changed as shown in a table.

The results are shown in Table 1.

(Examples 7 to 9 and Comparative Examples 6 to 9) In Example 1, the SB block copolymer was produced according to Production Example (1a) so that the composition was as shown in Table 1, and these were used. Other than that was carried out similarly.

The results are shown in Table 1.

(Comparative Example 10) When a SB block copolymer is produced, 10% by weight of tetrahydrofuran as a randomizing agent is added to n-hexane in Production Example (1a) to have a random component.
An SB block copolymer was obtained. The styrene content of this product is
It was 25% by weight, and the block PS part was 18% by weight. The same procedure as in Example 1 was carried out except that this SB block copolymer was used.

The results are shown in Table 1.

(Examples 10 and 11) According to Production Example (1a), a composition in which the composition of the SB block copolymer was changed as shown in Table 1 was used, and the content of the SB block copolymer in the resin was 15% by weight. Example 1 was carried out in the same manner as in Example 1 except that

The results are shown in Table 1.

[Advantages of the Invention] According to the present invention, it is possible to provide a styrene-based resin which has excellent gloss and impact resistance, and is particularly excellent in balance between gloss and impact resistance as compared with conventional high-impact polystyrene. it can.

Claims (2)

[Claims] 1. A styrene containing 92 to 60% by weight of (A) and (B)
The complete block styrene-butadiene block copolymer is copolymerized with 8 to 40% by weight, and the (B) complete block styrene-butadiene block copolymer is
Styrene content as a repeating unit is 10 to 50% by weight
And the molecular weight is in the range of 80,000 to 300,000, and the weight average molecular weight of the block polystyrenes part is 15,000 to 15
A styrene-based resin characterized in that the rubber particles have a diameter of 0.1 to 1.8 μm and the matrix has a molecular weight of 100,000 to 300,000. 2. The styrene resin according to claim 1, wherein the styrene is styrene.