JPH04122759A - Vinyl chloride resin composition - Google Patents

Abstract

PURPOSE:To improve the heat resistance, impact strength, and moldability of a vinyl chloride polymer by compounding it with a copolymer of styrene, an N-substd. maleimide monomer, and an unsatd. nitrile monomer. CONSTITUTION:100 pts.wt. vinyl chloride polymer is compounded with 5-50 pts.wt. copolymer which has a mol.wt. of 5000-2000000 and is prepd. by copolymerizing 20-80 wt.% styrene, 10-60 wt.% N-substd. maleimide monomer pref. selected from the group consisting of N-phenylmaleimide, N- cyclohexylmaleimide, N-chlorophenylmaleimide, and N-methylmaleimide, and 2-40wt.% unsatd. nitrile monomer pref. acrylonitrile.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has excellent heat resistance, impact resistance, and moldability, and thus can be used for roofing materials, sizing materials, electrical equipment parts, automobile parts, and pipe materials. The present invention relates to a vinyl chloride resin composition useful as a raw material for molding pipe joints, hoses, etc.

[Prior Art] Vinyl chloride resins have excellent physical and chemical properties and are very inexpensive, so they are widely used as various molding materials, film materials, and the like. However, on the other hand, it has the disadvantage that the molded product has poor heat resistance and moldability, so there is a problem that it cannot sufficiently respond to the diversification of uses.

Therefore, the following methods have been proposed as means to improve these shortcomings.

That is, as a means to improve the lack of heat resistance, there is a method of chlorinating vinyl chloride resin. Although the heat resistance of chlorinated vinyl chloride resin obtained by this method is considerably improved compared to conventional vinyl chloride resin, it is not necessarily sufficient, and on the other hand, chlorination actually worsens moldability. Because of this tendency, its applications are severely limited.

Therefore, when using chlorinated vinyl chloride resin as the base resin, a large amount of processing aids must be added.
In some cases, it may be necessary to blend a considerable amount of non-chlorinated vinyl chloride resin, making it impossible to effectively utilize the excellent heat resistance of chlorinated vinyl chloride resin.

As another method for improving the heat resistance of vinyl chloride resins, a method of blending a heat-resistant copolymer using a maleimide compound with a specific structure has been developed (Japanese Patent Publication No. 83
-57460, JP-A-62-240344, JP-A-61
-264037, 63-46249, etc.). However, with these methods, although heat resistance is improved, impact resistance is unavoidably reduced, and ultimately it is impossible to satisfy all requirements of heat resistance, impact resistance, and moldability.

Furthermore, a modifier using a copolymer obtained by copolymerizing N-substituted maleimide with α-methylstyrene, etc. as a modifier for vinyl chloride resin is also known (Japanese Patent Application Laid-open No. 34938/1989,
However, these modifiers have a relatively small proportion of N-substituted maleimide monomers in the total modifier, and moreover, vinyl chloride resin/
It is only used as one component of a polymer alloy made of ABS resin. Furthermore, since this modifier has a small content of maleimide monomer, it has poor compatibility with vinyl chloride resin, and particularly does not effectively exhibit impact resistance improvement effects.

[Problems to be Solved by the Invention] The present invention has been made with attention to the above-mentioned circumstances, and its purpose is to improve heat resistance while maintaining the characteristics that vinyl chloride resins have traditionally had. The aim is to establish a technology that can improve all properties such as mechanical strength, impact resistance, and moldability.

[Means for Solving the Problems] The vinyl chloride resin composition according to the present invention that can solve the above problems includes: [I] Vinyl chloride polymer; [II] Styrene: 20 to 88% by weight , N-substituted maleimide monomer: 10 to 60% by weight, and unsaturated nitrile monomer: 2 to 40% by weight. be.

[Function] The base resin used in the present invention is a vinyl chloride polymer [
I], which includes not only homopolymers of vinyl chloride, but also copolymers with vinyl chloride as the main polymerization component, and chlorinated vinyl chloride polymers with improved heat resistance by chlorinating them. However, in any case, a vinyl chloride polymer [I] in which vinyl chloride units account for 80 mol % or more is usually used. Furthermore, for applications requiring particularly high heat resistance, it is preferable to use chlorinated vinyl chloride polymers.

The present invention is characterized by the structure of the copolymer [11] that is blended as a modifier into the vinyl chloride polymer CI], so the copolymer [! I] will be explained in detail.

As mentioned above, this copolymer [II] contains styrene, N-
It is obtained by copolymerizing predetermined amounts of a substituted maleimide monomer and an unsaturated nitrile monomer. Copolymer [
II] The proportion of styrene units in
It is 88% by weight, more preferably in the range of 30 to 70% by weight, and if it is less than 20% by weight, the impact resistance and processability will be insufficient, and if it exceeds 88% by weight, the heat resistance will be insufficient, and the present invention A copolymer [If] having a modifying effect that meets the objective cannot be obtained.

Next, the N-substituted maleimide monomer is used to form a copolymer [II
] has the effect of increasing the heat resistance. The proportion of the monomer in the copolymer [II] is 10 to 60% by weight,
More preferably, it should be set in the range of 30 to 60% by weight; if it is less than 10% by weight, it will not be able to sufficiently improve the heat resistance of the copolymer [11], while if it exceeds 60% by weight, The affinity of the copolymer [II] with the vinyl chloride polymer [I] deteriorates, and the moldability of the resin composition deteriorates. In particular, when using chlorinated vinyl chloride as the vinyl chloride polymer, copolymers [! By using a resin composition having an N-substituted maleimide monomer content of 30 to 60% by weight as [2], a resin composition with even better physical properties, particularly impact resistance, can be obtained.

Specific examples of N-substituted maleimide-based caramers include N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-isobutylmaleimide, N-t-butylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-chlorophenylmaleimide, N-
Methylphenylmaleimide, N-bromophenylmaleimide, N-naphthylmaleimide, N-laurylmaleimide, 2-hydroxyethylmaleimide, N-hydroxyphenylmaleimide, N-methoxyphenylmaleimide, N-carboxyphenylmaleimide, N-nitrophenylmaleimide, etc. These can be used alone, or two or more types can be used in combination if necessary. Among these monomers, N-
Phenylmaleimide, N-cyclohexylmaleimide,
N-chlorophenylmaleimide and N-methylmaleimide.

Or, the unsaturated nitrile compound is the ffi resistant compound of copolymer [II]! It is an indispensable component for improving properties and solvent resistance, and the proportion of this monomer in the copolymer [11] is 2 to 40% by weight, more preferably 2 to 30% by weight.
Must be set within the range of % by weight. The monomer is 2
If it is less than 40% by weight, sufficient impact resistance cannot be imparted to the copolymer [II], while if it exceeds 40% by weight, not only the processability but also the impact resistance deteriorates. Specific examples of unsaturated nitrile monomers include acrylonitrile, methachloronitrile, phenyl acrylonitrile, etc. Among these, acrylonitrile is the most common. These unsaturated nitrile monomers can be used alone or, if necessary, two or more types can be used in combination.

The preferred ratio of the styrene-N-substituted maleimide monomer and the unsaturated nitrile monomer constituting the copolymer [II] is as described above, but the above-mentioned effects of each component may be comprehensively considered. The most preferable ratio for more effective performance is styrene diN = substituted maleimide monomer: unsaturated nitrile monomer = 30 to 68:3.
It ranges from 0 to 50.2 to 20.

There is no particular restriction on the molecular weight of the copolymer [11] obtained by copolymerizing the above three components, and it meets the requirements of the desired properties of the vinyl chloride resin composition, especially the moldability and molded product. It can be selected from a wide range depending on the degree of mechanical properties and heat resistance, etc., but the one for boat fishing is 5000 to 2.0
00,000 or so, more commonly 50,000 to 1,
000,000 range. The molecular weight may be adjusted by adjusting the amount of catalyst added during the copolymerization reaction, the temperature, and the amount of chain transfer agent (butyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, etc.) added.

There are no restrictions on the copolymerization method, and any of solution polymerization, emulsion polymerization, suspension polymerization, etc. may be employed. The polymerization initiators used during polymerization include commonly used free radical polymerization initiators, such as oil-soluble or water-soluble peroxides such as benzoyl peroxide, potassium persulfate, ammonium persulfate, hydrogen peroxide, etc. Azo compounds such as azobisisobutyronitrile can be used. At this time, it is also effective to use a reducing agent such as sodium bisulfite, ascorbic acid, or ferrous sulfate in combination to promote polymerization.

Examples of the organic solvent used in the solution polymerization include toluene, xylene, methyl isobutyl ketone, butyl cellosolve, dimethyl formamide, 2-methylpyrrolidone, Zolhetsuso +100 (manufactured by Tonen Petrochemical Co., Ltd.), and the like.

Examples of emulsifiers used during emulsion polymerization include anionic emulsifiers such as potassium evaporate, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate; nonionic emulsifiers such as polyoxyethylene nonylphenol ether and polyoxyethylene sorbitan ester. ;
Examples include cationic emulsifiers such as lauryltrimethylammonium chloride.

Examples of suspension stabilizers used during suspension polymerization include calcium carbonate, barium carbonate, magnesium carbonate, polyvinyl alcohol, and alkali metal salts of copolymers of methacrylic acid and methacrylic ester.

Which of the above copolymerization methods is particularly preferred? This is an 88-part method, and when this method is adopted, it is easy to obtain a copolymer [II] in which the three types of copolymerizable monomers are randomly copolymerized, and the modified vinyl chloride polymer [11] is easily obtained. A copolymer [II] with even better effects can be obtained. Incidentally, α-methylstyrene copolymer, which is known as a modifier for vinyl chloride polymers, is difficult to produce by solution polymerization, and it is difficult to produce it using a heterogeneous system such as suspension polymerization or bulk polymerization. Since copolymerization had to be carried out, a considerable amount of homopolymer was mixed in the product, which is thought to have hindered the improvement of the modification effect. In contrast, in the present invention, which uses styrene as the main monomer component, the copolymerization reaction can proceed homogeneously by adopting a solution polymerization method, so the amount of homopolymer produced can be suppressed to a low level, and the chlorination It is believed that a copolymer [II] having an excellent modifying effect on vinyl resins can be obtained. However, the method for producing the copolymer [II] used in the present invention is not limited to the solution polymerization method, and as described above, the copolymer [II] obtained by the emulsion polymerization method or the suspension polymerization method can be used. However, it can be used effectively as long as the type and usage ratio of the child picks meet the above-mentioned requirements.

The vinyl chloride resin composition of the present invention comprises the above-mentioned copolymer [I
I] and a vinyl chloride polymer [II], and the most common method for producing it is a method of melt-mixing the vinyl chloride polymer [II] and the copolymer [11] produced in advance. However, it is not limited to this method, and it is also possible to employ various methods as shown below, and products produced in this manner are also included in the technical scope of the present invention.

That is, the vinyl chloride polymer [1] is made to coexist in the monomer mixture used to produce the copolymer [II], and copolymerization is carried out in the coexistence system by solution polymerization, emulsion polymerization, suspension polymerization, etc. The resin composition of the present invention can be obtained by removing the solvent from the reaction product or coagulating, washing, and drying the polymerized components.

In order to effectively exhibit the above-mentioned modification effect by the copolymer [II], the preferred content of the copolymer [II] is 5 parts by weight per 100 parts by weight of the vinyl chloride polymer [1].
- 50 parts by weight, more preferably 5 to 30 parts by weight; if it is less than 5 parts by weight, the effect will not clearly appear, while if it exceeds 50 parts by weight, the vinyl chloride polymer [characteristics of II] This is not preferable because it not only reduces the excellent moldability, impact resistance, flame retardance, etc., but also increases the material cost.

The essential components of the present invention are vinyl chloride polymer [11] and copolymer [1], but other additives include general additives for vinyl chloride resins, such as plasticizers, fillers, stabilizers, Appropriate amounts of mold release agents, coloring agents, bleaching agents, antistatic agents, ultraviolet absorbers, etc. may be incorporated at will, and these are of course included within the technical scope of the present invention.

Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited by the following Examples.

[Example] Production example of copolymer Production example 1 199.2 parts of styrene in a fourth stainless steel flask with a stirrer (hereinafter 1 part means ``parts by weight'' unless otherwise specified) , 16.6 parts of acrylonitrile and 10 parts of methyl ethyl ketone were charged, and the mixture was heated to 80° C. under a nitrogen gas atmosphere.

Meanwhile, in another container, 116.2 parts of N-phenylmaleimide,
215.4 parts of methyl ethyl ketone and 1.5 parts of benzoyl peroxide were added and dissolved, and this solution was heated at 80°C.
The mixture was added dropwise over 5 hours into the above-mentioned 4-hole flask heated to a temperature of 50°C to carry out polymerization. The obtained polymer solution was diluted with 1690 parts of methyl ethyl ketone, and the polymer solution was diluted with 4 parts of methyl ethyl ketone.
The polymer was precipitated by pouring it into 500 parts of methanol, and then vacuum-dried to obtain 310 parts of copolymer (A) in the form of a white powder. The weight average molecular weight of this copolymer (A) was approximately 150.000 (confirmed by GPC).

Production Examples 2 to 5 In the same manner as Production Example 1, except that 332 parts of a monomer mixture having the composition shown in Table 1 was used instead of styrene, acrylonitrile, and N-phenylmaleimide in Production Example 1.
Copolymers (B) to (E) were obtained.

Production Example 6.7 A copolymer (
F) and (G) were obtained.

Comparative Production Example 1.2 A copolymer was produced in the same manner as in Production Example 1, except that 332 parts of a monomer mixture having the composition shown in Table 1 was used instead of styrene, acrylonitrile, and N-phenylmaleimide in Production Example 1. (H) and (I) were obtained.

In Comparative Production Example 2 in which α-methylstyrene was used instead of styrene, the reaction yield of α-methylstyrene was extremely low at 45%.

Examples 1 to 7 Copolymers (A) to (G) obtained in Production Examples 1 to 7 and chlorinated vinyl chloride resin (degree of polymerization 800, degree of chlorination 70%, manufactured by Tanemizu Kagaku Kogyo Co., Ltd., rHA31NJ) , MBS resin (manufactured by Kureha Chemical Co., Ltd., rBTA-3NxJ), stearic acid, polyethylene wax, lead stearate, and calcium stearate were placed in a Henschel mixer at the compounding ratio shown in Table 2, and mixed at 135°C for 2 minutes to obtain the resin. A composition was obtained. This resin composition was kneaded for 3 minutes using a hot roll with a diameter of 8 inches heated at 210°C to obtain a sheet-like resin composition, which was then heated at 200°C using a flat plate press to 150 g/g/
A specimen was prepared by press molding for 5 minutes under a pressure of cm2.

The heat distortion temperature (according to JIS K7207) and Charpy impact value (JIS K 711) of the obtained specimen
1) are also listed in Table 2.

Comparative Example 1.2 Copolymer (H), (I
), and other than that, resin compositions were prepared and molded in the same manner as in Examples 1 to 7, and performance evaluation was performed.

The results are shown in Table 2, and the resin compositions obtained in Examples 1 to 7 that meet the specified requirements of the present invention are the same as Comparative Example 1.
It can be seen that this resin composition has superior heat resistance and impact resistance compared to the resin composition obtained in No. 2.

[Effects of the Invention] The present invention is constructed as described above, and uses a copolymer obtained by copolymerizing styrene, N-substituted maleimide, and unsaturated nitrile polymer in a specific ratio as a modifying component to vinyl chloride. By blending into the system polymer, heat resistance, impact resistance,
It is now possible to provide a vinyl chloride resin composition with good moldability.

Claims (1)

[Claims] (1) [I] Vinyl chloride polymer, [II] Styrene: 20-88% by weight, N-substituted maleimide monomer: 10-60% by weight, and unsaturated nitrile monomer: 2-88% by weight A vinyl chloride resin composition having excellent heat resistance, impact resistance, and moldability, characterized by containing a copolymer obtained by copolymerizing 40% by weight.