JPH093286A - Vinyl chloride-based resin composition - Google Patents

Abstract

PURPOSE: To obtain the subject composition by blending a vinyl chloride-based resin with a specific amount of a prescribed partially saponified polyvinyl alcohol, excellent in thermal stability and transparency, preferably usable in the field of foods, medical treatment and daily necessaries. CONSTITUTION: This vinyl chloride-based resin composition is obtained by blending (A) 100 pts.wt. of a vinyl chloride-based resin with (B) 0.005-5 pts.wt. of a partially saponified polyvinyl alcohol which has 70-95mol% degree of saponification, 300-2,000 average degree of polymerization and contains at least one mercapto group at the molecular chain [e.g. a compound of the formula (Z is H or a mercapto group and at least one Z is a mercapto group; (x) and (y) are each an integer)] and, if required, (C) 1.5-5 pts.wt. of an atoxic stabilizer such as calcium zinc-based or barium zinc-based atoxic stabilizer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl chloride resin composition suitable for use in the fields of food, medical, daily necessities, etc. The present invention relates to an excellent vinyl chloride resin composition.

[0002]

2. Description of the Related Art Conventionally, vinyl chloride resins have been molded and processed by compounding non-toxic stabilizers such as Ca-Zn and Ba-Zn-based resins, and as general molding materials. Further, it is widely used as a product suitable for food, medical use and the like.

Molded products containing these non-toxic stabilizers have inferior ability to suppress thermal deterioration of the molded products, so that they have the drawbacks of impairing initial colorability of the molded products and insufficient thermal stability. It was Therefore, as a means for improving these drawbacks, a vinyl chloride resin to which an antioxidant is added or a compound having a hydroxyl group such as polyvinyl alcohol, glycerin, pentaerythritol, sorbitan fatty acid ester, sugar ester and its derivative is added. Compositions have been proposed (JP-A-63-234052, JP-A-58-15550, JP-A-49-111951,
JP-A-54-127950, JP-A-57-15163
No. 5, JP-A-58-27735).

However, in such a vinyl chloride resin composition, the effect of improving the thermal stability is not sufficient, or the above compounds have insufficient compatibility and dispersibility with the vinyl chloride resin, resulting in a decrease in transparency. Had a problem.

The present invention has been made in view of the above circumstances, and is a vinyl chloride resin composition capable of sufficiently maintaining thermal stability and transparency even when a non-toxic stabilizer is added to a vinyl chloride resin. The purpose is to provide.

[0006]

Means and Action for Solving the Problems The present inventors have
As a result of earnest studies to achieve the above object, as a result of having a saponification degree of 70 to 95 mol% and an average degree of polymerization of 300 to 2000 with respect to a vinyl chloride resin, and having a mercapto group at at least one of the molecular chain terminals. Even if a non-toxic stabilizer such as Ca-Zn based or Ba-Zn based is added to the vinyl chloride resin composition by blending a specific amount of partially saponified polyvinyl alcohol, thermal stability and transparency are sufficiently maintained. The present invention has been completed by finding out what can be done.

That is, the present invention is based on the vinyl chloride resin 100.
0.005 to 5 parts by weight of a partially saponified polyvinyl alcohol having a saponification degree of 70 to 95 mol%, an average degree of polymerization of 300 to 2000, and a mercapto group at at least one of the molecular chain terminals is used. A vinyl chloride resin composition characterized by the following.

The present invention will be described in more detail below. As described above, the vinyl chloride resin composition of the present invention is a partially saponified polyvinyl alcohol having a vinyl chloride resin having a mercapto group at at least one of its molecular chain terminals. Is blended in a specific amount.

The polymer raw material used to obtain the vinyl chloride resin is a vinyl chloride monomer, or a mixture of vinyl chloride based vinyl chloride monomer and a copolymerizable vinyl monomer. (50% by weight or more of vinyl chloride) is used. As the comonomer to be copolymerized with vinyl chloride, vinyl acetate, vinyl ester such as vinyl propionate, methyl acrylate, acrylate ester such as ethyl acrylate or methacrylic acid ester, ethylene, olefin such as propylene, Maleic anhydride, acrylonitrile, styrene, vinylidene chloride,
Other examples include monomers copolymerizable with vinyl chloride.

As a method of producing the vinyl chloride resin using these monomers, a method of suspension polymerization of the monomers in the presence of a polymerization initiator can be preferably adopted. , In that case, a commonly used dispersion aid, for example, water-soluble cellulose ether such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, partially saponified polyvinyl alcohol, acrylic acid polymer, water-soluble gelatin, etc. Polymers, sorbitan monolaurate, sorbitan trioleate, glycerin tristearate, oil-soluble emulsifiers such as ethylene oxide propylene oxide block copolymer, polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerin oleate, sodium laurate No problem even when used in combination, such as water-soluble emulsifiers helium, etc. One or two or more.

Further, as the polymerization initiator used in the above-mentioned polymerization, those conventionally used can be used,
For example, percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, diethoxyethyl peroxydicarbonate, t-butyl peroxypivalate, t-
Perester compounds such as hexyl peroxypivalate, t-butyl peroxyneodecanate, α-cumylperoxyneodecanate, acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate , 3, 5, 5-
Peroxides such as trimethylhexanoyl peroxide, azo compounds such as azobis-2,4-dimethylvaleronitrile and azobis (4-methoxy-2,4-dimethylvaleronitrile), and further potassium persulfate, ammonium persulfate, peroxide There are hydrogen oxide and the like, and these can be used alone or in combination of two or more.

The other conditions in the above polymerization, the aqueous medium to the polymerization vessel, the vinyl chloride monomer, and in some cases, other comonomers, dispersion aids, polymerization initiators and the like are charged in the same manner as in the conventional method. The charge ratio of these,
Regarding the polymerization conditions such as the polymerization temperature, the conventional technique can be similarly adopted.

Further, in this polymerization system, if necessary, a polymerization degree adjusting agent, a chain transfer agent, a pH adjusting agent, a gelation improving agent, an antistatic agent, an antioxidant which is appropriately used for vinyl chloride type polymerization. , A scale inhibitor, etc. can be optionally added.

The vinyl chloride resin composition of the present invention has a saponification degree of 70 to 95 mol%, preferably 75 to 92 mol%, and an average degree of polymerization of 300 to 2000, based on the vinyl chloride resin produced as described above. Preferably 500-1700
Then, a partially saponified polyvinyl alcohol having a mercapto group is added to at least one of the terminals of the molecular chain. As the partially saponified polyvinyl alcohol, a compound represented by the following general formula (1) is preferably used.

[0015]

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In the above formula, Z is a mercapto group or a hydrogen atom, but at least one is a mercapto group. x and y are integers that are the saponification degree and the average degree of polymerization.

If the degree of saponification and the average degree of polymerization are smaller or larger than the above ranges, the effects of improving thermal stability and transparency will be significantly reduced.

Further, the compounding amount of the partially saponified polyvinyl alcohol having a mercapto group at at least one of the molecular chain terminals is 0.0 with respect to 100 parts by weight of the vinyl chloride resin.
The amount is 05 to 5 parts by weight, and preferably 0.04 to 2 parts by weight. If the blending amount of partially saponified polyvinyl alcohol is less than 0.05 parts by weight, the effect of improving the thermal stability cannot be sufficiently obtained, and if it exceeds 5 parts by weight, the thermal stability is high in spite of increasing the blending amount. It is not economical because it becomes difficult to improve the effect of improving the sex.

According to the vinyl chloride resin composition of the present invention, even if a non-toxic stabilizer such as Ca-Zn system or Ba-Zn system is added to the composition, the improvement of thermal stability is improved. As a result, it is possible to have a sufficient heat stability property, and the transparency is also improved and improved. The amount of the non-toxic stabilizer blended is preferably 1.5 to 5 parts by weight with respect to 100 parts by weight of the vinyl chloride resin.

[0020]

EFFECT OF THE INVENTION According to the vinyl chloride resin composition of the present invention, even when a non-toxic composite stabilizer such as Ca-Zn system or Ba-Zn system is added to the composition, excellent thermal stability is obtained. That is, high transparency can be obtained.

[0021]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Production of vinyl chloride resin] Internal volume 2000
A stainless steel autoclave equipped with a L stirrer and a jacket was charged with 900 kg of deionized water, 300 g of partially saponified polyvinyl alcohol, and 420 g of t-butylperoxyneodecanoate, and the inside of the device was degassed to 50 mmHg. Then, 600 kg of vinyl chloride monomer was charged. While stirring the inside of the vessel, hot water was passed through the jacket to raise the temperature to 57 ° C., and polymerization was continued while maintaining the temperature. The reaction was stopped when the pressure inside the vessel had dropped to 6.0 kg / cm ² G, and the unreacted monomer was recovered. Next, the slurry was taken out of the container and dehydrated and dried to produce a vinyl chloride resin.

A mercapto group-containing partially saponified polyvinyl alcohol shown in Table 1 was added to the vinyl chloride resin obtained by the above method to produce a vinyl chloride resin composition,
The following tests were carried out.

[Thermal stability test] Vinyl chloride resin composition 1
00 parts by weight, 2.0 parts by weight of Ba-Zn-based composite stabilizer, 5.0 parts by weight of epoxidized soybean oil, dioctyl phthalate 4
5 parts by weight of the mixture was kneaded with a test roll at 150 ° C. for 5 minutes to prepare a 0.8 mm-thick sheet, which was placed in a Garr's oven until completely black at 190 ° C. The time (minutes) was measured and used as the value of thermal stability.

[Color tone and haze test] Regarding the color tone, the above-mentioned sheet was further pressed at 185 ° C for 5 minutes to form a transparent test piece having a thickness of 5 mm. The haze was measured as. Table 1 shows the results. The unit of partial saponification degree is mol%, the unit of thermal stability is minute, and the unit of haze is%.

[0026]

[Table 1] * In Comparative Example 2, partially saponified polyvinyl alcohol containing no mercapto group was used as an additive. ** In Comparative Example 3, pentaerythritol fatty acid ester was used as an additive.

From the results shown in Table 1, in the vinyl chloride resin compositions containing the mercapto group-containing partially saponified polyvinyl alcohols of Examples 1 to 4, Comparative Examples 1 to 3 were obtained.
It was found that the vinyl chloride resin composition had excellent thermal stability and higher transparency.

Claims (2)

[Claims] 1. A saponification degree of 70 to 95 mol% and an average degree of polymerization of 300 to 2 with respect to 100 parts by weight of a vinyl chloride resin.
And a vinyl chloride resin composition comprising 0.005 to 5 parts by weight of partially saponified polyvinyl alcohol having a mercapto group at at least one of the molecular chain terminals. 2. The partially saponified polyvinyl alcohol has the following general formula (1): (In the formula, Z is a mercapto group or a hydrogen atom, but at least one of Z is a mercapto group, and x and y are integers.) The vinyl chloride resin according to claim 1. Composition.