JP3089067B2 - Method for producing rubber-modified styrenic polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a rubber-modified styrenic polymer. Further, as a polymerization initiator,
Using a tetrafunctional organic peroxide having a specific chemical structure,
The present invention relates to a polymerization method and a method for producing a polymer having improved physical properties.

[0002]

2. Description of the Related Art Many methods have been proposed for producing styrene polymers and rubber-modified styrene polymers. Thermal polymerization in which a polymerization initiator such as an organic peroxide is not added at all has been performed for a long time, but in recent years, from the viewpoint of improving productivity, a method of adding a polymerization initiator has become mainstream.

[0003] Styrene-based resins are generally used in a wide variety of fields because of their excellent moldability, dimensional stability, colorability, electrical properties, safety, and the like. Therefore, in fields where a certain degree of durability is required, such as durable consumables and industrial parts, the necessity of improvement has become a major issue. As one of the measures for improving the strength of the styrene resin, increasing the molecular weight of the polymer has been proposed.

[0004] For example, a method using a cross-linking agent is inferior in fluidity, and the physical properties of the molded article are significantly reduced. In addition, by lowering the polymerization temperature or reducing the amount of the polymerization initiator, the average molecular weight can be increased to some extent, but on the other hand, the yield per unit time is greatly reduced.

[0005] Further, as a polymerization initiator, 1,1-di-t-
The use of butylperoxy-3,3,5-trimethylcyclohexane results in a polymer having a high molecular weight and a certain level of strength as compared with a conventional polymer, but is not sufficient in terms of moldability. .

[0006]

DISCLOSURE OF THE INVENTION The present invention is directed to a polymerization initiator for producing a rubber-modified styrenic polymer in order to solve such conventional disadvantages in production and in physical properties required for polymers. The examination was made.

[0007]

According to the present invention, when a rubber-like polymer is dissolved in a styrene-based polymer and then polymerized, a specific organic peroxide is used as a polymerization initiator in the polymerization system. It is an object of the present invention to provide a method for producing a rubber-modified styrene-based polymer having a high molecular weight and excellent mechanical strength and moldability without lowering the yield per unit.

When the method of the present invention is followed, high physical properties superior to those of any of the polymers obtained using conventionally known monofunctional, difunctional and trifunctional organic peroxides can be obtained. A good quality polymer can be provided.

That is, in the present invention, a tetrafunctional organic peroxide having the following specific chemical structure is used as a polymerization initiator when polymerizing a mixture obtained by dissolving a rubbery polymer in a styrene monomer. Is characterized by being polymerized using

[0010]

Embedded image

Wherein R ₁ and R _{2 each} have 1 to 1 carbon atoms.
2 alkyl groups and R represent an alkyl group having 1 to 5 carbon atoms or a phenyl group. ]

The tetrafunctional organic peroxide of the polymerization initiator used in the present invention includes 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane and 2,2-bis (4,4 -Di-t-amyl peroxycyclohexyl)
Propane, 2,2-bis (4,4-di-t-hexylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis ( 4,4-di-α-cumylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-butylperoxycyclohexyl)
Butane and 2,2-bis (4,4-di-t-amylperoxycyclohexyl) butane can be exemplified. These peroxy ketals can be synthesized relatively easily based on known production methods.

The addition amount of these tetrafunctional organic peroxides as a polymerization initiator is 0.0
If it is less than 0.005% by weight, there is no practical effect, and if it exceeds 0.5% by weight, the polymerization reaction rate is increased, and it becomes difficult to control the removal of polymerization heat and the like. .

In the present invention, organic peroxides which are always used for the polymerization of styrene monomers, for example, dibenzoyl peroxide, t-butylperoxybenzoate, 2,2-di (t-butylperoxide) Oxy) butane,
1,1-di-t-butylperoxycyclohexane,
At least one kind such as 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane may be used in combination. It is necessary that the amount added be such that the effect of the present invention is not impaired.

The styrene monomer in the present invention includes styrene, α-methylstyrene, t-butylstyrene, vinyltoluene and the like, and these may be used alone or as a mixture. A copolymerizable monomer such as acrylonitrile and methyl methacrylate can be added to these styrene monomers.

The rubbery polymer used in the present invention is E
PDM rubber, polybutadiene rubber, SBR, styrene / butadiene copolymer, styrene / butadiene block copolymer and the like. These may be used alone or in combination of two or more.

In the present invention, in the method for producing an impact-resistant styrene polymer obtained by grafting a styrene-based monomer to a rubber-like polymer, the amount of the rubber-like polymer used is preferably 20% by weight or less. If this is exceeded, the viscosity of the styrene-based monomer solution in which the rubber-like polymer is dissolved increases,
The stirring power of the polymerization apparatus becomes very large, which is not preferable from the top of the apparatus.

The polymerization temperature varies depending on the polymerization method and the combination of monomers, and is not uniform.
Preferably it is 80-160 degreeC. If the temperature is lower than 60 ° C., it is difficult to complete the polymerization reaction, which is not practical. On the other hand, when the temperature exceeds 160 ° C., the reaction rate becomes extremely large, and it becomes difficult to control the polymerization reaction.

In the present invention, the polymerization method is not particularly limited. Methods include, but are not limited to, lump, suspension, emulsification or lump / suspension. In the suspension polymerization, a dispersion stabilizer such as tribasic calcium phosphate, polyvinyl alcohol, and methylcellulose, various surfactants, and the like can be appropriately used. Further, a molecular weight regulator, a coloring agent, a plasticizer and the like may be added in advance during the polymerization. In the bulk polymerization, an aromatic hydrocarbon represented by ethylbenzene may be used as a solvent.

[0020]

Next, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 800 g of a styrene solution containing 50 g of polybutadiene dissolved in an autoclave having a capacity of 1 L, and 2,2-bis (4,4
4-di-t-butylperoxycyclohexyl) propane (trade name "Percadox 12" manufactured by Kayaku Akzo Co., Ltd.)
0.16 g (pure product conversion; 0.02%)]
Stir at rpm. The inside of the autoclave was purged with nitrogen gas, sealed, and heated.

After polymerization at 110 ° C. for 5 hours, the mixture was cooled to complete the preliminary polymerization. Next, 800 g of deionized water, 7 g of tribasic calcium phosphate, and 0.03 g of sodium dodecylbenzenesulfonate were added to a 2 L autoclave, and the mixture was added for 20 minutes.
Stir at 0 rpm, then add 2,2-bis (4,4-di-t-
1.44 g of butyl peroxycyclohexyl) propane
(0.18%) was added thereto, and the solution was replaced with nitrogen gas, sealed, heated, and heated at 100 ° C. for 5 hours.
Polymerization was performed at 35 ° C. for 3 hours, and then cooled. Neutralization, dehydration, and drying were performed according to a conventional method. This was further made into a normal pellet shape by an extruder. The physical properties were measured, and the results are shown in Table 1.

Example 2 Instead of 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane, 2,2-bis (4,4
-Di-t-amylperoxycyclohexyl) propane was used in the same manner as in Example 1. The results are shown in Table 1.

Example 3 Instead of 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane, 2,2-bis (4,4
-Di-t-butylperoxycyclohexyl) butane was used in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 The same as Example 1 except that monofunctional t-butylperoxybenzoate was used instead of 2,2-bis (4,4-di-t-butylperoxyhexyl) propane. I went to. The results are shown in Table 1.

Comparative Example 2 Instead of 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane, difunctional 1,1-di-tert-butylperoxy-3,3,5 -Same as Example 1 except that trimethylcyclohexane was used. The results are shown in Table 1.

Comparative Example 3 Example 3 was repeated except that trifunctional tris (t-butylperoxy) triazine was used instead of 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane. Performed similarly to 1. The results are shown in Table 1.

Table 1 Example Comparative Example 1 2 3 1 2 3 Polymerization initiator ABCDEF (wt%) 0.20 0.20 0.20 0.20 0.20 0.20 Intrinsic viscosity 1.03 1.00 1.02 0.78 0.96 0.95 [η] Izod impact strength 9.9 9.8 9.8 6.5 9.2 9.4 (Kg · cm / cm) Flexural strength 570 560 570 490 530 540 (Kg / cm ² ) MFI 3.3 3.2 3.3 2.9 2.7 2.8 (g / 10 min) Heat deformation temperature 92 91 92 84 87 88 (° C)

(Note) A: 2,2-bis (4,4-di-t-butylperoxycyclohexyl) fluorocarbon B: 2,2-bis (4,4-di-t-amyldioxycyclohexyl) fluorobenzene C: 2,2-bis (4,4-di-t-butylperoxycyclohexyl) phthalate D: t-butyldioxyoxydibenzoate (monofunctional) E: 1,1-di-tert-butyldioxy-3, 5,5-trimethylcyclohexane (bifunctional) F: tris (t-butylperoxy) triazine (trifunctional)

The various physical properties in the above table were measured by the following methods. (1) Intrinsic viscosity [η]: The specific viscosity of the toluene solution was measured, and [η] was determined by an ordinary method. (2) Izod impact strength: JIS
Conforms to K-6871. (3) Flexural strength: ASTM
According to D-790. (4) Melt flow index (MFI): JIS
Conforms to K-6870. (5) Heat deformation temperature: JIS
Conforms to K-6871.

From the above results, the polymer of the present invention obtained by using the tetrafunctional organic peroxide having the specific chemical structure represented by the general formula (1) as a polymerization initiator has been used conventionally. Clearly improved flowability and other practical properties compared to those obtained using monofunctional, difunctional and trifunctional organic peroxides You can see that it is.

[0032]

The rubber-modified styrenic polymer of the present invention comprises:
Various properties of the polymer have been improved, and this has been achieved by using a tetrafunctional organic peroxide having a specific chemical structure as a polymerization initiator, and from the viewpoint of improving productivity. Is also significant, and the industrial value is great.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C08F 12/00-12/36 C08F 251/00-292/00 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A method for producing a rubber-modified styrenic polymer, comprising using an organic peroxide represented by the general formula (1) as a polymerization initiator and polymerizing a styrenic monomer in the presence of a rubbery polymer. A method for producing a rubber-modified styrenic polymer, characterized in that: Embedded image Wherein R ₁ and R ₂ represent an alkyl group having 1 to ₂ carbon atoms, and R represents an alkyl group having 1 to 5 carbon atoms or a phenyl group. ]