JPS638410A - Improved impact-resistance styrene resin - Google Patents

Abstract

PURPOSE:To provide the titled resin of extremely good balance, outstanding in impact resistance, colorability and gloss, containing specified proportion of a special polybutadiene rubber with the rubber particle phase dispersed in the resin matrix having specific average particle size. CONSTITUTION:The objective resin can be obtained by using a polybutadiene rubber having such characteristics that 1,2-vinyl content is 35-70wt%, 1,4-cis content 10-60wt%, Mooney viscosity ML1+4 20-90, viscocity SV determined in the form of 5wt% styrene solution t 25 deg.C 20-120cps, ratio Mw/Mn <=3.8, and the ML1+4 and SV satisfy the relationship; 0.6ML1+4<=SV<=2.5ML1+4 so that its content in the resin matrix falls in the range 2-25wt% and the average particle size of the rubber particle phase dispersed in the matrix in the range 0.7-2.5mu. The polybutadiene rubber mentioned above can be prepared, for example, by solution polymerization of butadiene monomer catalysed by organolithium compound.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an impact-resistant styrenic resin that has excellent impact resistance and colorability, and has good surface gloss.

[Prior Art] Polystyrene is widely used for various purposes because it has excellent rigidity, transparency, gloss, etc., and good moldability. However, this polystyrene has a major drawback of poor impact resistance.Therefore, methods to improve this drawback include, for example, methods of mechanically blending a rubbery polymer with polystyrene, and methods of blending a styrene solution of a rubbery polymer into lumps. Methods such as polymerization or bulk suspension polymerization have been proposed. Particularly, the method of bulk polymerization or bulk suspension polymerization is widely practiced industrially because the obtained polymer has excellent physical properties. Rubbery polymers used as toughening agents in this method include polybutadiene rubber and styrene-butadiene copolymer rubber, and polybutadiene rubber in particular has excellent impact resistance. Widely used.

In recent years, impact-resistant styrene resins have been used in housings and parts for household electrical equipment, axle parts, and parts for office equipment1.
As it has become more popular in household goods and toys, various superior properties have come to be required.

In general, polystyrene, that is, so-called general polystyrene that does not contain a toughening agent, has better coloring properties than other resins, but in order to improve impact resistance, rubber-like toughening agents are added. It is known that when added to this, the coloring properties are significantly impaired.

For these reasons, there is an increasing demand for resins that maintain the properties of impact-resistant polystyrene resins and have improved colorability.

Conventionally, as a method to improve impact-resistant styrenic resin,
Two methods are known: one is to improve the rubber-like elastic material used, and the other is to improve the resin. For example, the former method is to improve the rubber-like elastic material by improving microscopic rubber-like polymers. Specification of structure (Japanese Patent Publication No. 52-88444, Japanese Patent Publication No. 53-44188), Specification of solution viscosity (Japanese Patent Publication No. 58-4934), Specification of the relationship between solution viscosity and Mooney viscosity (Japanese Patent Publication No. 58-4934) Methods such as 1 molecular weight distribution specification (Japanese Patent Publication No. 54-15912) have been proposed.

[Problems to be Solved by the Invention] However, although these methods improve physical properties such as impact strength, the improvement in colorability is not satisfactory.

Recently, therefore, various studies have been made to improve the colorability. For example, there is a method of limiting the microstructure, viscosity 1 molecular weight distribution, etc., as described in Japanese Patent Publication No. 23891/1993. Although colorability is improved by such a method, the surface gloss of the resin, which is one of our objectives, has not been improved to a satisfactory level.

In view of these circumstances, in order to develop an impact-resistant styrene-based resin that has good impact resistance, especially Izot impact strength and colorability, and has good gloss, we conducted studies based on concepts and knowledge that are different from conventional ones. .

In other words, it is said that falling weight impact strength and isot impact strength are excellent when the 1,2-vinyl content of the rubber-like toughening agent used in impact-resistant styrenic resin is in the range of 15 to 35% (Japanese Patent Publication No. 1973- Publication No. 44188.

(See Japanese Patent Publication No. 58-L934).

However, from the perspective of improving colorability, we conducted extensive studies on a wider range of rubbery toughening agents, and surprisingly found that one of the rubbery toughening agents, which had previously been considered unfavorable from the standpoint of impact strength. It has been discovered that in the range of 2-vinyl content of 35% or more, a resin with excellent isot impact strength and colorability and good gloss can be obtained.

[Means for Solving the Problems] That is, in the present invention, the polybutadiene rubber content is 2 to 25% by weight, and the average particle size of the rubber particle phase dispersed in the resin is 0.7 to 2.5% by weight. 5 impact-resistant styrenic resin, the polybutadiene rubber used has a vinyl content of 1.2 and 3.
5-70%, 1,4-cis content 10-60%, Kamouni viscosity (ML+ -a) 20-90.5 wt% styrene solution viscosity (SV) 20-+20c measured at 25°C
ps, weight average molecular weight (Ml, l) and number average molecular weight (M
n ) ratio M, /Mn is 3.8 or less, 0.6ML
This impact-resistant styrene resin is characterized by being a polybutadiene rubber with a relationship of 4≦SV≦2.5ML+44.

The present invention will be explained in more detail below.

The specific polybutadiene rubber used in the present invention can be obtained by solution polymerization using an organolithium compound as a catalyst. As organic lithium, organic monolithium such as n-butyllithium and 5ec-butyllithium is generally used, but as shown in JP-A-57-40513, 1,2-dilithio-1,2-diphenyl A mixture of a polyfunctional organolithium such as ethane, 1,4-dilithio-2-ethylcyclohexane, and an organomonolithium, or a reaction product containing an organomonolithium and a polyvinyl aromatic compound (e.g., divinylbenzene), etc. There is.

The particular polybutadiene rubber used in the present invention has a 11.2 vinyl content of 35-70%, preferably 35-55%, and a 1,4 cis content of 10-60%. If it is outside this range, the colorability will be greatly reduced.

The method for producing polybutadiene rubber having such a specific microstructure may be any conventionally known method as long as it produces the above structure. Ethers such as dimethyl ether, diethyl ether, and tetrahydrofuran, thioethers such as dimethyl sulfide and diethyl sulfide, dimethylethylamine, triethylamine,
Examples include a method of polymerizing by adding a polar compound such as amines such as tri-n-propylamine. Even if the vinyl bonds are uniform throughout the molecular chain.

As shown in Japanese Patent Publication No. 4B-875, it may change gradually along the molecular chain, or it may be linked in a block manner, and it is sufficient that the content is 35 to 70% by weight as a whole. , 1. In order to polymerize the 2-vinyl bond uniformly in the molecular chain, the polymerization initiation temperature is usually set at 30°C.
A method of polymerizing at a constant temperature of ~90°C is used as much as possible.

In addition, in order to polymerize the 1,2-vinyl bond so that it gradually decreases along the molecular chain, a method in which the polymerization is carried out at an elevated temperature is used. A method is used in which the polymerization end temperature is set at 85 to 120°C.

The polybutadiene rubber used in the present invention has a Mooney viscosity (
ML1+a) 20-90, preferably 24-75, with a 5 wt% styrene solution viscosity (SV
)20-120cps, preferably 30-110cps
, more preferably 40 to 110 cps, and 0.8
ML1+4≦SV≦2.5ML1.4, preferably 0.7ML1+4≦SV≦2.5ML+・4, and the weight average molecular weight (Mw) and number average molecular weight (M
The ratio M w /M n of o) is 3.8 or less, preferably 3.4 or less.

Regarding the molecular 31 cloth of the conjugated diene polymer rubber thus obtained, the molecular weight distribution curve of CPC (gel permeation chromatography) may be monomodal, bimodal, trimodal, etc. May be polymodal.

If the Mooney viscosity is less than 20, the #impact styrenic resin obtained will have poor Izot impact strength, and if the Mooney viscosity is less than 30.
If it exceeds this, it takes time to dissolve the rubber in styrene, resulting in poor productivity. Furthermore, drying during rubber production is difficult, which is industrially disadvantageous.

In addition, if the SV is less than 20CP3, the #impact styrene resin obtained will have poor Izot impact strength, and 5v120
If it exceeds 0.7 to 2.5, it will be difficult to control the dispersed rubber particle phase and the gloss will be poor.

Surprisingly, the dispersed rubber particle phase has 0.7 to 2.5 stripes and the polybutadiene rubber used is 0.8MI, 1+a
≦SV≦2.5ML1.4, and (M w
/Mn) of 3.8 or less, excellent impact resistance and gloss are maintained, and the effect of improving colorability is large.

In the case of Mata, Q, lliML+, a>SVte, it is difficult to stably control the dispersed rubber particle phase in the range of 0.7 to 2.5, and the Izot impact strength is inferior. SV＞2
．． 5ML+ and a have poor gloss.

Furthermore, if the ratio (M w / M n ) exceeds 3.8, excellent gloss and coloring properties cannot be maintained.

The content of the specific polybutadiene rubber constituting the present invention is 2
-25% by weight, particularly preferably 4-15% by weight. When the rubber content is less than 2% by weight, no improvement in the isot impact strength is observed, and when the rubber content exceeds 25% by weight, the solution viscosity is high and it becomes difficult to control the rubber particle size.

As mentioned above, the polybutadiene rubber used in the present invention has a limited relationship between MLl, 4 and SV, as well as (M, 1Mn ratio), so one method for obtaining such polybutadiene rubber is is a constant temperature, preferably 20
A method in which a butadiene monomer and a hydrocarbon solvent are placed in a polymerization vessel maintained at a temperature of 130°C to 130°C, and an organolithium catalyst is fed into this solution at a constant rate to complete the polymerization reaction. A method of adjusting the supply rate and polymerization temperature of divinylbenzene, a method of adding a small amount of divinylbenzene to the polymerization system (see Japanese Patent Publication No. 39-17074), or a method of adding a polybutadiene living polymer polymerized using an organolithium compound as a catalyst. Halides such as silicon chloride, methyltrichlorosilane, carbon tetrachloride,
Coupling reaction with a polyfunctional coupling agent such as a gelatin compound such as diethyl adipate [e.g.
Journal of Polymer Science 7th
l of PolymerScier+ce Part
A, Val 3.93-103.1115), British Patent No. 1223079, etc.], or a combination of the above-mentioned methods is also useful. In the case of a method of coupling a living polymer with a polyfunctional coupling agent, the method of polymerizing the living polymer is simply a method of polymerizing with an organic monolithium such as n-butyllithium;
Examples include a method of polymerizing organic dilithium such as diphenylethane in a mixture with organic dilithium, and a method of polymerizing a reaction product containing three of organic monolithium and a polyvinyl aromatic compound (for example, divinylbenzene).

Although the specific polybutadiene rubber used in the present invention can be produced by such a method, other conventionally known methods may be used as long as the above range is satisfied.

In the impact-resistant styrenic resin of the present invention, the gel content (content of toluene-insoluble matter) is preferably in the range of 10 to 40% by weight, and the swelling index of the gel in the resin in toluene is The molecular weight of the resin portion is preferably in the range of 7 to 13, and the weight average molecular weight of the resin portion is preferably in the range of 100,000 to 400,000, more preferably in the range of 180,000 to 280,000. The amount of styrene oligomer remaining in the resin affects impact resistance, so it is usually preferably 1% by weight or less, and in particular for products where impact resistance is required, it is preferably 0.5% by weight or less. .

The impact-resistant styrenic resin of the present invention may be obtained by any known method as long as it satisfies the requirements of the present invention. In particular, bulk polymerization or bulk-suspension polymerization may be used. preferable.

Hereinafter, embodiments of the bulk polymerization method and the bulk-suspended/i-polymerization method will be described. In general, in bulk polymerization, the specific polybutadiene rubber of the present invention is dissolved in styrene and polymerized under heat, usually at 85 to 200'' in the case of no catalyst, while in catalytic polymerization, it is generally at a lower temperature, i.e.
The polymerization operation is continued at 0-150° C. until the polymerization of styrene is substantially complete.

In the case of catalytic polymerization, 1,1-bis(t-
butylperoxy)cyclohexane, 1,1-bis(t
-butylperoxy) 3,3.5-) peroxyketals such as dimethylcyclohexane, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, Dialkyl peroxides such as dicumyl peroxide, diacyl peroxides such as benzoyl peroxide, m-toluoyl peroxide, lauroyl peroxide, di-myristyl peroxydicarbonate, diimpropyl peroxycarbonate, etc. peroxydicarbonates,
t-butyl peroxyisopropyl carbonate, t-
Peroxy esters such as butyl peroxy acetate, di-butyl ciberoxyisophthalate, t-butyl peroxybenzoate, ketone peroxides such as cyclohexanone peroxide, methyl ethyl ketone peroxide, p-mentha hydroperoxide, t-butyl peroxybenzoate, etc. Hydroperoxides such as -butyl hydroperoxide and cumene hydroperoxide, azo compounds such as azobisisobutyronitrile and azobiscyclohexanecarbonitrile, and the like are used. These may be used alone or in combination of two or more. Furthermore, if necessary, chain transfer agents such as mercaptans, α
- Methystyrene linear dimer, terpinolene can be used.

During this bulk polymerization, known internal lubricants are often used,
For example, if liquid paraffin is added in an amount of 1 to 5 parts by weight based on 1 part by weight of the polymer after completion of polymerization, if the resulting polymer contains a small amount of unreacted styrene (t~5%), such styrene It is desirable to remove the devolatilizers by known methods, such as vacuum removal or extrusion equipment designed for the purpose of devolatilization. Stirring during such bulk polymerization is performed as necessary, but it is desirable to stop or moderate the stirring after the conversion rate of styrene into a polymer, that is, the polymerization rate of styrene has progressed to 80% or more. . Excessive stirring may reduce the strength of the resulting polymer. Further, if necessary, polymerization may be carried out in the presence of a small amount of a diluent such as toluene or ethylbenzene, and after the completion of the polymerization, these diluents may be removed by heating together with unreacted styrene.

Bulk suspension combination polymerizations are also useful in making the high impact polystyrenes of this invention. In this method, the first half of the reaction is carried out in bulk, and the second half is carried out in suspension. That is, a styrene solution of the specific butadiene rubber of the present invention is subjected to heat polymerization in the absence of a catalyst or polymerization with the addition of a catalyst in the same manner as in the previous bulk polymerization, and usually 50% or less of the styrene, preferably 10 to 40%, is partially polymerized. Polymerize to This is bulk polymerization before and after.

Next, this partially polymerized mixture is dispersed in an aqueous medium under stirring in the presence of a suspension stabilizer or both this and a surfactant, and the second half of one reaction is completed by suspension polymerization, and finally It is washed, dried, and, if necessary, made into pellets or powder for practical use.

In addition to the above methods, useful impact-resistant styrenic resins can be obtained by conventionally known methods that are modified or improved.

In addition, a part of the styrene forming the impact-resistant styrenic resin together with the specific polybutadiene in the present invention may be replaced with a monomer other than styrene that can be radically copolymerized with styrene. The monomer is used in an amount of 50% by weight or less based on the total monomers including styrene. Such copolymerizable monomers other than styrene include monovinyl aromatic hydrocarbons such as α-methylstyrene, vinyltoluene, vinylethylbenzene, vinylxylene, and vinylnaphthalene, butadiene,
One or more types of heptamines selected from conjugated dienes such as isoprene, acrylonitrile, methyl methacrylate, etc. are used.

The impact-resistant styrenic resin of the present invention can be used as a variety of practically useful products by processing methods such as injection molding and extrusion molding. Furthermore, during processing, antioxidants may be added as necessary.
UV absorber, flame retardant.

Other thermoplastic resins such as lubricants, mold release agents, fillers, etc., such as general polystyrene, methacrylic resin, polyphenylene ether, polycarbonate, styrene-butadiene block copolymer resin, methyl methacrylate-styrene copolymer resin, maleic anhydride - May be used in combination with styrene copolymer resin, etc.

[Effects of the Invention] ゛The impact-resistant styrenic resin of the present invention obtained in this manner has excellent impact resistance, coloring properties, and gloss, and is extremely well-balanced compared to conventional impact-resistant styrenic resins. It is a resin with a smooth texture, and the industrial significance of the present invention is great.

[Examples] Some examples are shown below to show specific embodiments of the present invention, but these are intended to explain the gist of the present invention more specifically, and are not intended to limit the present invention. isn't it.

(1) Production of rubber-like polymer sample Polybutadiene rubber was polymerized according to the method shown below under the conditions and amounts shown in Table 1.

Clean and dry an autoclave with a stirring device and a jacket with a capacity of 10 ml, purify it in advance after replacing it with nitrogen.

After adding dry n-hexane 7 and then adding tetrahydrofuran as a vinylating agent and adjusting the autoclave internal liquid temperature to the starting temperature, 5% by weight of n-butyllithium was added.
The n-hexane solution and dried butadiene were respectively added continuously for polymerization. Silicon tetrachloride was added as a coupling agent to the obtained polymer and reacted for 30 minutes.

2,6-sheets were added to the resulting polymer solution as a stabilizer.
0. rt-butyl-4-methylphenol (BIT).
5 phr was added and the solvent was removed by heating to obtain polybutadiene rubber samples A to I and N shown in Table 1.

Samples No.-M were obtained in the same manner as Sample A under the conditions shown in Table 1, with the addition of divinylbenzene and n-benzene at the same time.

Sample 0 was prepared under the conditions shown in Table 1, except that instead of n-butyllithium, an organolithium-based catalyst made of a reaction product containing at least a monoorganolithium compound and a processed polyvinyl aromatic compound was used. Obtained in the same manner as Sample A.

The method for preparing the organolithium-based catalyst used in sample O is shown in the table below.
Shown in A.

Table A (Note) Divinylbenzene/n-butyllithium (molar ratio) The catalyst prepared by the method in Table A was soluble in n-hexane. Divinylbenzene used was a southern limit divinylbenzene containing 57% by weight of a mixture of divinylbenzene isomers, with the balance consisting of ethylvinylbenzene and diethylbenzene.

The properties of the obtained polybutadiene rubber are shown in Table 1.

Mooney viscosity was ML+, 4 (100°C), and 5% by weight styrene solution viscosity was measured at 25°C using a Cannon-Fenske viscometer. Furthermore, the microstructure was investigated using the Morello method [La cbimica
E L'imdustria, 41,758 (195
9)], and the ratio of (M w / M n ) was measured using GPC (Model M-6000 manufactured by Waters, USA).
The measurement was carried out using the following conditions.

Solvent: Tetrahydrofuran Column: Loose Styla gel manufactured by Waters, USA Mesh size: 103 people, 104A, 105A, 106A
1 each Column temperature: 35°C Liquid flow rate: 1 OtsR/min Liquid pressure: 700 psi Sample concentration: 20.1% by weight Sample liquid volume: 0.5 aJ Detector: Differential refractometer (2) #impact styrene Production of Resin Resins Impact-resistant styrenic resins were obtained using each of the rubbers listed in Table 1 by the bulk polymerization method described below.

That is, 7 parts by weight of each of the various rubbers shown in Table 1 were added to styrene S3.
It was uniformly dissolved in 1710 parts by weight. This was transferred to a reactor equipped with a stirrer and a jacket, and 1X10-4 moles of di-tert-butyl peroxide was added per mole of styrene, heated at 110°C for 3 hours, and heated at 140°C for 5 hours.
The reaction was carried out for 2 hours at iso°C.

During the reaction, the number of stirring was controlled in order to adjust the average particle size of the rubber particle phase.

After removing unreacted substances from the obtained polymer at 230°C under reduced pressure,
Adding 0.5 parts by weight of BHT per 100 parts by weight of the polymer,
It was pelletized using an extruder. The average particle diameter was measured using a Coulter counter and expressed as a 50% median diameter.

Izotsu impact strength is measured by thickness 3 made by compression molding.
．． Measurement was performed using No. 21 test pieces according to JIS K-7110.

Gloss is 150mm x 150+am, thickness 2III
Injection molding was performed using an ffi mold with a single pin gate, and the average gloss value of the gate part and the opposite side of the gate was determined according to JIS K 8.
Measured according to 741.

The colorability was determined by adding 0.3 parts of micro carbon blank to 100 parts of resin and injection molding in a 150 mm x 150 mm, thickness 2) mold with a single bin gate. Those with excellent coloring properties were rated 4, those with the poorest coloring properties were rated 1, and those in between were rated 3 and 2.

The results obtained are shown in Table-2.

As is clear from the results of Examples 1 to 9 in Table 2, when impact-resistant polystyrene is polymerized using the polybutadiene rubber of the present invention, a resin with excellent impact resistance, colorability, and good gloss is obtained. I know what I'm getting.

It can be seen that even when methyl methacrylate or acrylonitrile is used as part of the styrene in Examples 10 and 11, resins with good impact resistance, gloss, and coloring properties can be obtained.

On the other hand, as shown in Comparative Examples 1 and 5, the 1,2 vinyl content of polybutadiene rubber or (M, /Mll)
If the ratio is outside the range of the present invention, the coloring properties will be poor.

Also, as shown in Comparative Examples 2, 3, and 4.6, Voliv)) x 7':! (7) M L + -4 value, S
It can be seen that when the correlation between the V value, MLI, 4 value, and SV value is outside the range of the present invention, the impact resistance or gloss deteriorates.

Procedures Amendment Written by the Commissioner of the Patent Office on July 29, 1986 Black 1) Akio Yu 1, Indication of Case Patent Application No. 151492/1982 2, Name of Invention Improved Impact Resistant Styrenic Resin 3, Amendment Patent Applicant: 1-1-2 Yurakucho, Chiyoda-ku, Tokyo Representative Director and President of Hiki Elastomer Co., Ltd. Takao Yokoyama 4, Agent: 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Sanshin Building Room 204 Telephone: 501-21385, "Detailed Description of the Invention" column 6 of the specification to be amended, Contents of the amendment (1) Change "Impact resistance" to "Heat resistance" on page 12, line 11 of the specification tube. To sex,” he corrected.

(2) On page 12, line 13 of the same book, "impact resistance" is corrected to "heat resistance".

(3) In the same book, page 18, line 7, “Content capacity 10”
The content is 10 sentences long.''

(4) In the same book, page 18, line 9, "n-hexane 7" is corrected to "n-hexane 7 sentences."

(5) On page 818, line 20 of the same book, "Sample Work~M is" is corrected to "Sample JM is."

(6) In the same section, page 19, line 5, "processed product" is corrected to "compound."

Procedure Amendment Written by the Commissioner of the Patent Office on October 1, 1986 Black 1) Mr. Yu Akira1, Indication of Case Patent Application No. 151492/19822, Name of Invention Improved Impact Resistant Styrenic Resin Chiyoda, Tokyo 1-2, Yurakucho-ku, President and CEO of Hiki Elastomer Co., Ltd. Takao Yokoyama 4, Representative: Room 204, Sanshin Building, 1-4-1, Yurakucho, Chiyoda-ku, Tokyo Telephone: 501-21385, Statement subject to amendment Contents of amendment in Column 6 of "Detailed Description of the Invention" (1) On page 11, line 17 of the Specification section, "Organodilithium in a mixture with organic dilithium" was changed to "In a mixture of organic silium and organic monolithium" ” he corrected.

Claims (1)

[Claims] The polybutadiene rubber content is 2 to 25% by weight, and the average particle size of the rubber particle phase dispersed in the resin is 0.7 to 25% by weight.
The polybutadiene rubber used is an impact-resistant styrenic resin with a particle diameter of 2.5μ (1) 1,2 vinyl content of 35 to 70%, 1,4 cis content of 10 to 60% (2) Mooney viscosity (ML_1_+_4 ) is 20-90
(3) Viscosity of 5 wt% styrene solution measured at 25°C (S
V) is 20 to 120 cps (4) Weight average molecular weight (M_w) and number average molecular weight (M
__n) ratio M_w/M_n is 3.8 or less, 0.6ML
An impact-resistant styrenic resin characterized by being a polybutadiene rubber having a relationship of _1_+_4≦SV≦2.5ML_1_+_4.