JP3032373B2 - Polybutadiene-based composition and impact-resistant polystyrene-based resin using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art ABS resins have been mainly used for housings and mechanical parts of home electric appliances such as televisions and videos, and housings of displays and keyboards of OA equipment. These applications require high gloss as well as impact resistance, and ABS resin is a resin that can sufficiently satisfy such requirements.

However, there is a problem that the ABS resin is more expensive than other more general-purpose resins such as polystyrene and polypropylene. For this reason, home appliance manufacturers and OA equipment manufacturers are studying alternatives to less expensive resins without reducing the performance of the products. One of such resins is an impact-resistant polystyrene resin. This resin is a resin exhibiting considerably high impact resistance and excellent in injection moldability, and is further characterized by being less expensive than ABS resin. For this reason, impact-resistant polystyrene resins have come to be widely used in televisions and video housings in place 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. The rubber particles exhibit considerably high impact resistance by absorbing impact energy. However, impact-resistant polystyrene resins have lower gloss than ABS resins and ordinary polystyrene resins, and this has been an obstacle to further expanding applications. It has already been known that the use of a polybutadiene having a low solution viscosity as a particle-dispersed polybutadiene in an impact-resistant polystyrene resin can improve the gloss of the impact-resistant polystyrene resin. However, when polybutadiene having only a low solution viscosity is used, the gloss of the impact-resistant polystyrene resin is improved, but the impact resistance is greatly reduced.

Some technical measures have already been tried to obtain an impact-resistant polystyrene resin having high gloss and excellent impact resistance. An example of this is disclosed in
There is a method disclosed in 148213. This method
After 1,3-butadiene is polymerized with an alkyllithium-based catalyst to form low-cis polybutadiene, a branching agent such as tetrachlorosilane is reacted, and the resulting branched low-cis polybutadiene is dissolved in a styrene monomer and subjected to radical polymerization. Impact-resistant polystyrene resin.

[0006]

The impact-resistant polystyrene resin thus obtained has improved gloss and impact resistance as compared with the prior art. 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 solving the above-mentioned problems, the present inventor has found that by using a polybutadiene-based composition having a specific composition for the rubber component, gloss and impact resistance are more remarkable than before. The present inventors have found that an improved impact-resistant polystyrene resin can be obtained, thereby achieving the present invention.

More specifically, the present invention comprises (A) 20 to 95% by weight of a linear polymer and (B) 80 to 5% by weight of a radial polymer having a structure represented by the formula (1). (A), (b) and (c), a polybutadiene-based composition having the conditions (P) n-X (1) wherein 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-bonded segment contained in the polymer in the composition. (B) 1,4-cis bond in which the bonding mode of the butadiene segment is in the following range. 90 to 99.5% 1,4-trans bond 0.5 to 9% 1,2-bond 0 to 3% (c) Weight average molecular weight is in the range of 50,000 to 500,000, expressed by weight average molecular weight / number average molecular weight. Molecular weight distribution is 1.2 to
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. In the polybutadiene-based composition of the present invention, the content of the radial polymer component of the B component is 5 to 80, preferably 10 to 60,
Particularly preferably, it is in the range of 20 to 50% by weight. If the content of the radial polymer component is less than 5% by weight or more than 80% by weight, the performance of the impact-resistant polystyrene resin obtained by using the resin is greatly reduced due to the gloss and impact resistance, which is not preferable. .

In the formula (1) representing the structure of the radial polymer component, X is a reactive residue of a 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 using the same decreases, and when n is less than 3, the impact resistance decreases, which is not preferable. Further, it is natural that the radial polymer component may be a mixture of polymers having different numbers of branches.

The other polymer component in the polybutadiene composition of the present invention is an unbranched linear polymer of the component A. In addition, in the polybutadiene-based composition of the present invention, in addition to the polymer component specified in the present invention, compounds such as stabilizers, antioxidants, and UV inhibitors which are added to ordinary rubber products can be naturally 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 butadiene segments contained in the polymer in the composition is 90% or more, preferably 95% or more, and generally 100% is most preferred. If the weight content of the butadiene segment is less than 90%, the performance is undesirably reduced due to the relationship between gloss and impact resistance, which is one object of the present invention.

In the polybutadiene-based composition of the present invention, the binding mode of the butadiene segment is such that the 1,4-cis bond content is at least 90%, preferably at least 92%, particularly preferably at least 95%. 1,4-cis bond content is 9
If it is less than 0%, it is not preferable because the performance is deteriorated due to the relationship between the gloss and the impact resistance of the impact-resistant polystyrene resin obtained using the same. Further, the 1,2-bond content must be 3% or less, preferably 2% or less, particularly preferably 1% or less. If the 1,2-bond content exceeds 3%, the resulting impact-resistant polystyrene resin is undesirably deteriorated in performance due to the relationship between the gloss and the impact resistance. The remaining mode of attachment of the butadiene segment is a 1,4-trans linkage;
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 the polymer components is in the range of 50,000 to 500,000, preferably 100,000 to 400,000, particularly preferably 150,000 to 300,000. If the weight-average molecular weight is less than 50,000, the impact resistance of the impact-resistant polystyrene resin obtained therefrom is undesirably reduced, and if it exceeds 500,000, the gloss is undesirably reduced. Further, the molecular weight distribution represented by weight average molecular weight / number average molecular weight of the polymer component is 3.5 or less, preferably 3.0 or less, more preferably 2.5 or less.
If the molecular weight distribution exceeds 3.5, the gloss of the impact-resistant polystyrene resin obtained using the same is undesirably reduced. In general, the molecular weight distribution of the polybutadiene composition is preferably narrow, but a distribution of less than 1.2 is technically difficult to produce.

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

The method for producing the linear polymer component A in the polybutadiene composition of the present invention is not particularly limited. B
As with the components, a composite catalyst mainly composed of a rare earth metal such as neodymium or a composite catalyst mainly composed of a known transition metal such as nickel, cobalt, and titanium is used, butadiene alone or in the presence of another conjugated diene, It can be obtained by polymerization or solution polymerization in a hydrocarbon solvent.

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

The polybutadiene composition of the present invention can be used for various rubber applications such as tires in addition to the production of the impact-resistant polystyrene resin of the present invention, as well as the conventionally known polybutadiene. When the above-mentioned polybutadiene is used in the impact-resistant polystyrene resin of the present invention, it must be 2 to 20% by weight based on 98 to 80% by weight of polystyrene.

The proportion of the polybutadiene composition is 2% by weight
If it is less than 30, the resulting impact-resistant polystyrene resin does not sufficiently improve impact resistance, and the proportion of polybutadiene is less than 20%.
If the amount is more than 10% by weight, the mechanical strength and rigidity of the impact-resistant polystyrene resin are notably reduced, which is not preferable. The impact-resistant polystyrene resin of the present invention includes, in addition to the polybutadiene-based composition specified in the present invention, a butadiene-based polymer that is not specified in the present invention, for example, randomly branched high-cis polybutadiene, 1,4 of butadiene segment. -Rubber components such as polybutadiene, styrene butadiene rubber, ethylene propylene rubber, ethylene-vinyl acetate copolymer rubber, and acrylic rubber having a cis content of less than 90% can also be added. These rubber components can be added up to 30 parts by weight based on 100 parts by weight of the polybutadiene-based composition of the present invention.

Further, in the impact-resistant polystyrene resin of the present invention, when producing the impact-resistant polystyrene resin, a vinyl monomer capable of radical copolymerization with styrene, for example, a substituted aromatic vinyl compound such as α-methylstyrene. Alternatively, a methacrylate such as methyl methacrylate may be used as a comonomer. Such a vinyl monomer can be used up to 30 parts by weight based on the styrene monomer.

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

[0022]

Examples of the present invention will be described below.

[0023]

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

After the polymerization, 0.38 mmol of butyl trimellitate was added as a coupling agent and reacted at 50 ° C. for 1 hour. After the reaction, BHT [2,6-bis (tert
The reaction was stopped by adding 100 mmol of a 10% by weight solution of -butyl) -4-methylphenol] in a mixed solvent of methanol / cyclohexane, and then the solvent was evaporated by heating to obtain a polymer.

The structure of the obtained polymer was analyzed by the following method. (1) The binding mode of the butadiene segment was measured using an infrared spectrophotometer, and determined by data processing according to 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 determined as the 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. The data is shown as the average number of branches of the radial component.

Table 1 shows the structure of the obtained polymer.

[0027]

Examples 2 and 3 and Comparative Example 1 In Examples 2 and 3 and Comparative Example 1, the amounts of the composite catalyst and the coupling agent to be used were adjusted, and the other conditions were operated in the same manner as in Example 1.
Table 1 shows the structure of the obtained polymer.

[0028]

Comparative Example 2 Comparative Example 2 was carried out 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. Table 1 shows the structure of the obtained polymer.

[0029]

Example 4 The polybutadiene composition of Example 4 was obtained by mechanically mixing the polymers obtained in Comparative Examples 1 and 2 at 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 styrene monomer was added.
48 g of the polybutadiene-based composition was added and dissolved to obtain an 8% by weight styrene solution of the polybutadiene-based composition. 0.2 g of n-dodecyl mercaptan was added to this solution,
The mixture was stirred at 135 ° C. and preliminarily polymerized until the conversion of styrene became 30%. Next, 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 polymerization. The polymerization was carried out at 100 ° C. for 2 hours, then at 125 ° C. for 3 hours, and further at 140 ° C. for 2 hours while stirring the autoclave.

A beaded polymer was collected from the obtained reaction product mixture by filtration, washed with water, dried, and then extruded into pellets to obtain about 500 g of pellets of the impact-resistant polystyrene resin of the present invention. The obtained pellet-shaped impact-resistant polystyrene resin is injection-molded to prepare a test piece for a physical property test, and the Izod impact strength, gloss, Vicat softening temperature,
The rubber particle size in the resin was measured. The melt index (MI) of the pellet is JIS K7210 (200 ° C, 5k
g), Izod impact strength was measured according to JIS K7110 (notched).

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

[0033]

Examples 6 to 8 and Comparative Examples 3 and 4 An impact-resistant polystyrene composition was prepared in the same manner as in Example 5, except that polybutadiene of the type shown in Table 2 was used. The obtained impact-resistant polystyrene 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 size in the resin were measured.
The measurement of these physical properties was performed in the same manner as in Example 5. Table 3 shows the results.

[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 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 size in the resin were measured. The measurement of these physical properties was performed in the same manner as in Example 5. Table 3 shows the results.

[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 the Izod impact strength, gloss, Vicat softening temperature, and rubber particle size in the resin were measured. The measurement of these physical properties was performed in the same manner as in Example 5. Table 3 shows the results.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

According to the impact-resistant polystyrene resin of the present invention, the correlation between gloss and impact resistance is remarkably improved as compared with conventional impact-resistant polystyrene. Further, in terms of basic resin performance such as heat resistance and rigidity, the resin is excellent in balance with the performance of the resin as compared with the conventional resin.

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Claims (3)

(57) [Claims] 1. A straight-chain polymer
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 is determined by the following conditions (a), (b) and (c). A polybutadiene-based composition having (P) nX (1) where P is a linear polymer chain, n is an integer of 3 to 20, and X is a reactive residue of a terminal coupling agent. (A) In the polymer in the composition, 90% by weight or more of the butadiene-bonded segment contained (b) The bonding mode of the butadiene segment is in the following range 1,4-cis bond 90 to 99.5% 1,4-trans bond 0.5 to 9% 1, 2-Combination 0 to 3% (c) Weight average molecular weight is in the range of 50,000 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-based composition according to claim 1, wherein the polymer segment constituting the composition comprises only a butadiene segment. 3. The polybutadiene-based composition according to claim 1 or 2, and a styrene-based polymer from 98 to 20% by weight.
An impact-resistant polystyrene resin consisting of 80% by weight.