JPH05279515A - Polybutadiene composition and high-impact polystyrene resin containing the same - Google Patents

Abstract

PURPOSE:To obtain a polybutadiene compsn. which is useful as a rubber component for preparing a high-impact polystyrene resin excellent in gloss and impact strength by compounding a linear polymer with a specific radial polymer and specifying the average mol.wt. and molecular structure of the compsn. as a whole. CONSTITUTION:This compsn. comprises 20-95wt.% linear polymer (e.g. polybutadiene) and 80-5wt.% radial polymer of the formula: (P)n-X (wherein P is a linear polymer chain; (n) is 3-20; and X is a residue of a terminal-coupling agent) (e.g. a polymer obtd. by polymerizing 1,3-butadiene under specified conditions and reacting the resulting polymer with butyl trimellitate as a coupling agent) and has, based on the compsn., a content of butadiene segments of at least 90wt.%, a wt.-average mol.wt. of 50,000-500,000, and a mol.wt. distribution (expressed by wt.-average/number-average mol.wt.) of 1.2-3.5. Of all the butadiene segments, 90-99% are linked by 1,4-cis bonding; 0.5-9%, by 1,4-trans bonding; and 0-3%, by 1,2-bonding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polybutadiene-based composition which can be preferably used as a rubber component of an impact-resistant polystyrene-based resin, and an impact-resistant polystyrene-based resin using the polybutadiene-based composition as a rubber component.

[0002]

2. Description of the Related Art Conventionally, ABS resin has been mainly used for housings and mechanical parts of home electric appliances such as televisions and videos, and for housings of displays and keyboards of OA equipment. For these applications, impact resistance and high gloss are required, and ABS resin is a resin that can sufficiently satisfy such requirements.

However, the ABS resin has a problem that it is expensive as compared with other more general-purpose resins such as polystyrene and polypropylene. For this reason, home appliance manufacturers and OA equipment manufacturers are considering alternatives with cheaper resins without degrading product performance. An impact-resistant polystyrene-based resin is one of such resins. This resin has a feature that it has a considerably high impact resistance and is excellent in injection moldability, and that the price is lower than that of ABS resin. For this reason, impact-resistant polystyrene resins have come to be widely used in television and video housings instead of ABS resins.

The impact-resistant polystyrene resin has a structure in which rubber particles such as polybutadiene having a diameter of 0.1 to 10 μm are dispersed in a continuous phase of polystyrene. Since the rubber particles absorb impact energy, they exhibit considerably high impact resistance. However, the impact-resistant polystyrene-based resin has a low gloss as compared with the ABS resin and the ordinary polystyrene-based resin, which has been an obstacle to further expanding the application. It is already known that the gloss of the impact-resistant polystyrene resin can be improved by using polybutadiene dispersed in particles in the impact-resistant polystyrene resin having a low solution viscosity. However, when only polybutadiene having a low solution viscosity is used, there is a problem that the impact resistance of the polystyrene resin is greatly reduced although the gloss of the impact resistant polystyrene resin is improved.

Several technical measures have already been attempted in order to obtain an impact-resistant polystyrene resin having high gloss and excellent impact resistance. As an example of this, Japanese Patent Laid-Open No. 61-
There is a method disclosed in Japanese Patent No. 148213. This method
After polymerizing 1,3-butadiene with an alkyllithium-based catalyst to form low-cis polybutadiene, a branching agent such as tetrachlorosilane is reacted to dissolve the branched low-cis polybutadiene in a styrene monomer, and radical polymerization is performed. Impact-resistant polystyrene resin.

[0006]

The impact-resistant polystyrene-based resin thus obtained has improved gloss and impact resistance as compared with conventional ones. However, its impact resistance is not yet sufficient, and further improvement has been required.

[0007]

Means for Solving the Problems As a result of intensive studies on the solution of the above-mentioned problems, the present inventor has found that the use of a polybutadiene-based composition having a specific composition as a rubber component makes both gloss and impact resistance more remarkable than ever before. It has been found that an improved impact-resistant polystyrene-based resin can be obtained, and the present invention has been achieved.

That is, the present invention comprises (A) a linear polymer 20 to 95% by weight (B) a radial polymer having a structure represented by the formula (1) 80 to 5% by weight, and the average of all components is as follows. (A), (b) and (c) of the polybutadiene composition (P) n-X (1) where P is a linear polymer chain, n is an integer of 3 to 20, and X is (A) 90% by weight or more of butadiene bond segment contained in the polymer in the composition (b) 1,4-cis bond in which the bonding mode of the butadiene segment is within the following range 90-99.5% 1,4-trans bond 0.5-9% 1,2-bond 0-3% (c) Weight average molecular weight is in the range of 50,000 to 500,000, expressed as weight average molecular weight / number average molecular weight. The molecular weight distribution is 1.2-
It is in the range of 3.5.

The impact-resistant polystyrene resin of the present invention comprises 2 to 20% by weight of the above polybutadiene composition and 98 to 80% by weight of a styrene polymer. The content of the radial polymer component of the component B in the polybutadiene composition of the present invention is 5 to 80, preferably 10 to 60,
It is particularly preferably in the range of 20 to 50% by weight. If the content of the radial polymer component is less than 5% by weight or exceeds 80% by weight, the performance of the impact-resistant polystyrene resin obtained by using the same is significantly deteriorated due to the relationship between gloss and impact resistance, which is not preferable ..

In the formula (1) representing the structure of the radial polymer component, X is a reaction residue of the terminal coupling agent.
N represents the number of branches of the radial polymer and is an integer in the range of 3 to 20, preferably 3 to 10, and particularly preferably 3 to 6. When n exceeds 20, the gloss of the impact-resistant polystyrene resin obtained by using it decreases, and conversely, when n is less than 3, the impact resistance decreases, which is not preferable. Further, it is a matter of course that the radial polymer component may be a mixture of polymers having different branch numbers.

The other polymer component in the polybutadiene composition of the present invention is an unbranched linear polymer of component A. Further, in the polybutadiene composition of the present invention, in addition to the polymer component defined in the present invention, a compound such as a stabilizer, an antioxidant, an ultraviolet ray inhibitor or the like which is usually added to rubber products can be added.

In the polymer component of the polybutadiene composition of the present invention, the monomer copolymerized with butadiene is selected from conjugated dienes other than butadiene and vinyl aromatic compounds. However, the weight content of the butadiene segment contained in the polymer in the composition is 90% or more, preferably 95% or more, and generally 100% is most preferable. When the weight content of the butadiene segment is less than 90%, the performance is lowered due to the relationship between gloss and impact resistance, which is one of the purposes of the present invention, which is not preferable.

In the polybutadiene composition of the present invention, the bonding mode of the butadiene segment is such that the 1,4-cis bond content is 90% or more, preferably 92% or more, particularly preferably 95% or more. 1,4-cis bond content 9
If it is less than 0%, the performance is deteriorated due to the relationship between the gloss and impact resistance of the impact-resistant polystyrene resin obtained using this, which is not preferable. The 1,2-bond content must be 3% or less, preferably 2% or less, and particularly preferably 1% or less. If the 1,2-bond content exceeds 3%, the performance is deteriorated due to the relationship between the gloss and impact resistance of the resulting impact-resistant polystyrene resin, which is not preferable. The remaining bonding mode of the butadiene segment is 1,4-trans bonding,
It is in the range of 0.5 to 9%.

In the polybutadiene composition of the present invention, the weight average molecular weight of all polymer components is in the range of 50,000 to 500,000, preferably 100,000 to 400,000, and particularly preferably 150,000 to 300,000. When the weight average molecular weight is less than 50,000, the impact resistance of the impact-resistant polystyrene resin obtained by using the same is lowered, which is not preferable, and when it exceeds 500,000, gloss is lowered, which is not preferable. Further, the molecular weight distribution represented by the weight average molecular weight / number average molecular weight of the polymer component is 3.5 or less, preferably 3.0 or less, and more preferably 2.5 or less.
When the molecular weight distribution exceeds 3.5, the gloss of the impact-resistant polystyrene resin obtained by using it is lowered, which is not preferable. The polybutadiene composition preferably has a narrow molecular weight distribution, but a distribution of less than 1.2 is technically difficult to produce.

The polybutadiene composition of the present invention, especially B
The radial polymer component of the component is, for example, a composite catalyst containing a rare earth metal such as neodymium as a main component, butadiene alone or in the presence of another conjugated diene, bulk polymerization or solution polymerization in a hydrocarbon solvent, and a carbonyl group after polymerization. An organic compound having, particularly an ester compound or carbonate compound of an organic acid having two or more carboxylic acid groups in the molecule,
It can be obtained by coupling the polymer ends.

The method for producing the linear polymer component of the component A in the polybutadiene composition of the present invention is not particularly limited. B
Similar to the component, a composite catalyst containing a rare earth metal such as neodymium as a main component, or a composite catalyst containing a known transition metal such as nickel, cobalt, or titanium as a main component allows butadiene alone or in the presence of another conjugated diene to form a block. It can be obtained by polymerization or solution polymerization in a hydrocarbon solvent.

In the polybutadiene composition of the present invention, the mixing method of the components A and B is not particularly specified. Both can be mixed as a polymerization solution after polymerization, or can be mixed in a lump by a mechanical mixer. Further, it can be achieved by sequentially dissolving both polymer components in a styrene monomer during the production of the impact resistant polystyrene resin. Furthermore, by using a composite catalyst containing a rare earth metal as a main component, butadiene alone or in the presence of another monomer, bulk polymerization or solution polymerization in a hydrocarbon solvent, and adjusting the amount of the terminal coupling agent added after the polymerization. The polybutadiene composition of the present invention can be obtained immediately by coupling a part of the polymer terminal.

The polybutadiene-based composition of the present invention can be used not only for producing the impact-resistant polystyrene-based resin of the present invention but also for various rubber applications such as tires in the same manner as conventionally known polybutadiene. When the above-mentioned polybutadiene is used for the impact-resistant polystyrene-based resin of the present invention, it should be 2 to 20% by weight with respect to 98 to 80% by weight of polystyrene.

The proportion of the polybutadiene composition is 2% by weight
If it is less than 1, the impact-resistant polystyrene-based resin obtained does not have sufficiently improved impact resistance, and the proportion of polybutadiene is 20.
When the content exceeds the weight%, the mechanical strength and rigidity of the impact-resistant polystyrene resin are remarkably lowered, which is not preferable. The impact-resistant polystyrene-based resin of the present invention includes, in addition to the polybutadiene-based composition defined in the present invention, a butadiene-based polymer that does not meet the requirements of the present invention, such as randomly branched high-cis polybutadiene and 1,4 of the butadiene segment. A rubber component such as polybutadiene having a cis content of less than 90%, styrene butadiene rubber, ethylene propylene rubber, ethylene-vinyl acetate copolymer rubber, and acrylic rubber may be added. These rubber components can be added up to 30 parts by weight based on 100 parts by weight of the polybutadiene composition of the present invention.

Furthermore, in the impact-resistant polystyrene-based resin of the present invention, a vinyl-based monomer radical-copolymerizable with styrene during production of the impact-resistant polystyrene-based resin, for example, a substituted aromatic vinyl compound such as α-methylstyrene. Alternatively, a methacrylic acid ester such as methyl methacrylate may be used as a comonomer. Such vinyl monomers can be used up to 30 parts by weight with respect to the styrene monomer.

The impact-resistant polystyrene resin of the present invention is
It can be produced by a known polymerization method such as a bulk polymerization method, a bulk-suspension method or a suspension polymerization method, for example, a method described in JP-A-57-143313.

[0022]

EXAMPLES Examples of the present invention will be shown below.

[0023]

Example 1 The inside of a sufficiently dried 10 liter pressure-resistant autoclave was sufficiently replaced with dry nitrogen and used for polymerization.
After press-fitting 6000 g of cyclohexane mixed solution containing 900 g of 1,3-butadiene into the autoclave,
Neodymium isopropyl-5-methylhexanoate 2.7 mmol, diisobutylaluminum hydride 44 mmol, ethylaluminum sesquichloride Cl /
Nd was added so as to have an element ratio of 3 and polymerization was carried out at 50 ° C. for 2 hours.

After the polymerization, 0.38 mmol of butyl trimellitate as a coupling agent was added, and the mixture was reacted at 50 ° C. for 1 hour. After the reaction, BHT [2,6-bis (tert
-Butyl) -4-methylphenol] in an amount of 100 mmol liter of a 10% by weight methanol / cyclohexane mixed solvent solution was added to stop the reaction, and then the solvent was heated to be volatilized to obtain a polymer.

The structure of the obtained polymer was analyzed by the following method. (1) The bonding mode of the butadiene segment was determined by measuring with an infrared spectrophotometer and processing the data by the method of Morello. (2) The molecular weight was measured by gel permeation chromatography using THF (tetrahydrofuran) as a developing solvent. (3) The content of the branched polymer was obtained as a weight content of the branched polymer contained in the polymer by performing peak analysis of GPC data. (4) The average number of branches of the radial polymer is GPC-LA.
It was determined by the LLS (Low Angle Laser Light Scattering) method. Data are shown as the average number of branches of the radial component.

The structure of the obtained polymer is shown in Table 1.

[0027]

Examples 2, 3 and Comparative Example 1 In Examples 2, 3 and Comparative Example 1, the amounts of the composite catalyst and the coupling agent used were adjusted, and other conditions were the same as in Example 1.
The structure of the obtained polymer is shown in Table 1.

[0028]

Comparative Example 2 Comparative Example 2 was operated in the same manner as in Example 1 except that the amount of the mixed catalyst used was adjusted and no coupling agent was used at all. The structure of the obtained polymer is shown in Table 1.

[0029]

Example 4 The polybutadiene composition of Example 4 was obtained by mechanically mixing the polymers obtained in Comparative Examples 1 and 2 in a weight ratio of 1: 1. Table 2 shows the structure of the obtained polymer.

[0030]

Example 5 A 1-liter separable flask was replaced with nitrogen gas, and 552 g of a styrene monomer was added.
48 g of the polybutadiene-based composition of was added and dissolved to obtain an 8 wt% styrene solution of the polybutadiene-based composition. To this solution was added 0.2 g of n-dodecyl mercaptan,
The mixture was stirred at 135 ° C. and prepolymerized until the polymerization rate of styrene reached 30%. Then, this solution was charged into a 2-liter autoclave, 700 ml of a 0.5% by weight aqueous solution of polyvinyl alcohol was added, and 1.4 g of benzoyl peroxide and 0.7 g of dicumyl peroxide were added.
Was added to carry out further polymerization. The polymerization was carried out at 100 ° C. for 2 hours, then at 125 ° C. for 3 hours, and at 140 ° C. for 2 hours while stirring the autoclave.

From the resulting reaction product mixture, a bead-like polymer was collected by filtration, washed with water, dried, and then pelletized by an extruder to obtain about 500 g of pellets of the high impact polystyrene resin of the present invention. The obtained pellet-shaped impact-resistant polystyrene-based resin is injection-molded to prepare a test piece for a physical property test, Izod impact strength, luster, Vicat softening temperature,
The rubber particle size in the resin was measured. Melt index (MI) of pellets is JIS K7210 (200 ° C, 5k
g), Izod impact strength was measured according to JIS K7110 (notched).

The gloss and the Vicat softening temperature are JIS Z8741 (60 °) and JIS K7206, respectively.
(Load 1 kg) was measured. Rubber particle size is
It was measured using a Coulter counter of Nikka Seiki. The results are shown in Table 3.

[0033]

Examples 6 to 8 and Comparative Examples 3 and 4 Impact-resistant polystyrene compositions were prepared in the same manner as in Example 5 except that polybutadienes of the types shown in Table 2 were used. The obtained impact resistant polystyrene resin composition was injection-molded to prepare a test piece for a physical property test, and Izod impact strength, gloss, Vicat softening temperature, and rubber particle diameter in the resin were measured.
These physical property values were measured in the same manner as in Example 5. The results are shown in Table 3.

[0034]

Example 9 An impact-resistant polystyrene composition was prepared in the same manner as in Example 5, except that 528 g of styrene and 72 g of the polybutadiene composition of Example 2 were used. The obtained impact-resistant polystyrene-based resin composition was injection-molded to prepare a test piece for a physical property test, and the Izod impact strength, gloss, Vicat softening temperature, and rubber particle diameter in the resin were measured. The measurement of these physical property values was performed in the same manner as in Example 5. The results are shown in Table 3.

[0035]

Example 10 An impact-resistant polystyrene composition was prepared in the same manner as in Example 5, except that 570 g of styrene and 30 g of the polybutadiene composition of Example 2 were used. The obtained impact resistant polystyrene resin composition was injection-molded to prepare a test piece for a physical property test, and Izod impact strength, gloss, Vicat softening temperature, and rubber particle diameter in the resin were measured. The measurement of these physical property values was performed in the same manner as in Example 5. The results are shown in Table 3.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

INDUSTRIAL APPLICABILITY The impact-resistant polystyrene resin of the present invention has a significantly improved correlation between gloss and impact resistance as compared with conventional impact-resistant polystyrene. Further, in terms of basic resin performance such as heat resistance and rigidity, it is no better than conventional resins, and the performance of the resin is well balanced.

Claims (3)

[Claims] 1. A linear polymer (A)
20 to 95% by weight (B) 80 to 5% by weight of a radial polymer having a structure represented by the formula (1), and the average of all components satisfies the following conditions (a), (b) and (c). A polybutadiene-based composition having. (P) n-X (1) Here, P is a linear polymer chain, n is an integer of 3 to 20, and X is a reaction residue of the terminal coupling agent. (A) For the polymer in the composition 90% by weight or more of contained butadiene bond segment (b) The bonding mode of the butadiene segment is in the following range: 1,4-cis bond 90-99.5% 1,4-trans bond 0.5-9% 1, 2-bond 0 to 3% (c) Weight average molecular weight is in the range of 5 to 500,000, and molecular weight distribution represented by weight average molecular weight / number average molecular weight is 1.2 to
It is in the range of 3.5. 2. The polybutadiene composition according to claim 1, wherein the polymer segment constituting the composition is composed of only a butadiene segment. 3. A polybutadiene-based composition according to claim 1 or 2 in an amount of 2 to 20% by weight and a styrenic polymer 98 to
Impact-resistant polystyrene resin containing 80% by weight.