JPH08113601A - Production of vinyl chloride polymer - Google Patents

Abstract

PURPOSE: To obtain a vinyl chloride polymer excellent in meltability, mechanical strengths and heat stability. CONSTITUTION: Vinyl chloride or a vinyl chloride monomer mixture based thereon in an amount of 100 pts.wt. is copolymerized with 0.10-0.25 pts.wt. monomer having at least two vinyl-polymerizable double bonds in the molecule in the presence of 0.005-0.10 pt.wt. 2-mercaptoethanol to obtain a vinyl chloride polymer having a tetrahydrofuran-insoluble gel fraction of 0-0.01wt.% and an Mw/Mn ratio (wherein Mw is the weight-average molecular weight, and Mn is the number-average molecular weight) of 2.5-6.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing a vinyl chloride polymer comprising vinyl chloride or a mixture of vinyl chloride monomers mainly containing vinyl chloride.
The vinyl chloride-based polymer obtained by the present invention has a low melt viscosity and excellent moldability, and thus is suitably used as a gasket for a large window frame for vehicles, a material for rotational molding, and the like.

[0002]

2. Description of the Related Art Conventionally, a vinyl chloride resin gasket made by injection molding has been used as a window frame for a vehicle. The molding of the gasket and the step of attaching it to the window glass are performed separately. Was there. On the other hand, recently, in order to simplify the process, a method of directly molding a gasket for a window frame into a window glass, which is called module molding, has been studied. In such module molding, the conventional vinyl chloride polymer has a problem that the injection pressure is too high, and RIM molding using polyurethane has been mainly adopted.

However, since polyurethane has a problem of high price, a vinyl chloride polymer which has a low melt viscosity applicable to module molding and is excellent in thermal stability and mechanical strength has been desired. On the other hand, even in rotational molding, which is also used for molding instrument panels for vehicles, there is a situation in which high pressure cannot be applied during molding.Therefore, a vinyl chloride polymer with similar excellent meltability is desired. It is rare.

[0004]

Many proposals have been made for a method of producing a vinyl chloride polymer having excellent meltability. First, polymer particles having a relatively high degree of polymerization are formed, and then the surroundings thereof are formed. A method of forming a polymer having a low degree of polymerization is known, and therefore, a method of changing the polymerization temperature during the polymerization (Japanese Patent Laid-Open No. 49-28910) or a method of changing the polymerization temperature during the polymerization, And adding a chain transfer agent such as a halogenated aliphatic hydrocarbon (Japanese Patent Laid-Open No. Sho 60)
-72906) are known.

However, when a halogenated aliphatic hydrocarbon is added as a chain transfer agent, a high degree of wastewater treatment is required to treat unreacted halogenated aliphatic hydrocarbon mixed in the decanter wastewater. was there.

The present invention has been made in view of the above problems, and an object of the present invention is to solve the above problems and to provide a vinyl chloride-based polymer having excellent meltability, mechanical strength and thermal stability. It provides a coalesce.

[0007]

Means for Solving the Problems As a result of intensive investigations by the present inventors to improve the melt flowability, mechanical strength and thermal stability of vinyl chloride polymers, vinyl chloride monomer or vinyl chloride was obtained. 0.005 per 100 parts by weight of a vinyl chloride monomer or a mixture of vinyl chloride-based monomers mainly containing vinyl chloride when suspension-polymerizing a mixture of vinyl chloride-based monomers mainly containing In the presence of 0.10 part by weight of 2-mercaptoethanol, a vinyl chloride monomer or a vinyl chloride-based monomer containing vinyl chloride as a main component is used as a monomer having two vinyl polymerizable double bonds in the molecule. By adding 0.10 to 0.25 parts by weight to 100 parts by weight of the mixture of monomers and copolymerizing the mixture, the tetrahydrofuran insoluble gel content is 0 to 0.01% by weight, and the weight average molecular weight (M ) And the ratio of the number average molecular weight (Mn) (M
A vinyl chloride-based polymer having a w / Mn of 2.5 to 6.0 is obtained, and the vinyl chloride-based polymer is used for the module molding for the large window frame and the rotation for the instrument panel described above. They have found that they are suitable for molding and have excellent meltability, mechanical strength and thermal stability, and have completed the present invention.

The present invention will be described in more detail below.

The present invention mainly comprises vinyl chloride monomers or vinyl chloride during suspension polymerization of a vinyl chloride monomer or a mixture of vinyl chloride-based monomers mainly containing vinyl chloride in an aqueous medium. Mixture of vinyl chloride monomers 10
In the presence of 0.005-0.10 part by weight of 2-mercaptoethanol per 0 part by weight, a monomer having two vinyl polymerizable double bonds in the molecule is added to vinyl chloride monomer or vinyl chloride. Mixture of vinyl chloride-based monomers 1
It is characterized in that it is added in a ratio of 0.10 to 0.25 parts by weight per 100 parts by weight, whereby the tetrahydrofuran insoluble gel content is 0 to 0.01% by weight, and the weight average molecular weight (Mw) is Ratio of number average molecular weight (Mn) (M
A vinyl chloride polymer having a w / Mn of 2.5 to 6.0 is obtained. In addition, (Mw / Mn) is 3.0
More preferably, it is ˜4.0.

On the other hand, when the tetrahydrofuran-insoluble gel content exceeds 0.01% by weight, the melt viscosity increases and the mechanical strength decreases, so that the object of the present invention cannot be achieved. Further, if (Mw / Mn) is less than 2.5, the effect of lowering the melt viscosity is not sufficient, while if it exceeds 6.0, the mechanical strength is lowered and the object of the present invention cannot be achieved.

In the method of the present invention, the polymerization of a vinyl chloride monomer with a monomer having two vinyl polymerizable double bonds in the molecule is carried out by vinyl chloride monomer or vinyl chloride based vinyl chloride. 0. 0 per 100 parts by weight of the mixture of vinyl monomers.
It is carried out in the presence of 005 to 0.10 part by weight of 2-mercaptoethanol. When the amount of 2-mercaptoethanol is less than 0.005 parts by weight, the tetrahydrofuran insoluble gel content exceeds 0.01% by weight,
An increase in melt viscosity and a decrease in mechanical strength occur. On the other hand, when the amount of 2-mercaptoethanol exceeds 0.10 parts by weight, the polymerization rate is remarkably lowered and the productivity is lowered, which is not practical.

Further, 2-mercaptoethanol is 0.0
Even if it is present in an amount of from 05 to 0.10 parts by weight, the addition amount of the monomer having two vinyl polymerizable double bonds in the molecule is such that a vinyl chloride monomer or a vinyl chloride monomer mainly containing vinyl chloride is used. When the amount is less than 0.10 parts by weight per 100 parts by weight of the mixture of monomers, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) becomes less than 2.5, and the melt viscosity The effect of lowering is not sufficient. On the other hand, when the content exceeds 0.25 part by weight, the tetrahydrofuran-insoluble gel content exceeds 0.01% by weight, resulting in an increase in melt viscosity and a decrease in mechanical strength.

The monomer having two double bonds in the molecule is not particularly limited, but examples thereof include diallyl phthalate, diallyl isophthalate, diallyl terephthalate, and other diallyl esters of phthalic acid, diallyl maleate. , Diallyl fumarate, diallyl itaconate and other ethylenically unsaturated dibasic acid diallyl esters, diallyl sebacate and other saturated dibasic acid diallyl esters, diallyl ether, ethylene glycol divinyl ether, n-butanediol divinyl ether ,
Examples thereof include divinyl ethers such as octadecane divinyl ether, and dimethacrylic esters or diacrylic esters of polyhydric alcohols such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate and dimethylene glycol diacrylate.

A monomer having two double bonds in the molecule is
It can be added before or during the polymerization and is not particularly limited, but the polymerization conversion is performed in order to completely react the added monomer having two double bonds in the molecule to stabilize the quality. It is preferable to add it when the rate is 70% or less.

Although the polymerization temperature is not particularly limited,
For example, the temperature is 20 to 80 ° C., and among these, 35
˜70 ° C. is preferable in terms of productivity and the molecular weight of the obtained polymer.

The monomer raw material of the vinyl chloride-based polymer is a vinyl chloride monomer alone or 50% by weight or more of a vinyl chloride monomer and a vinyl-based monomer copolymerizable with the vinyl chloride monomer. It is a mixture. The vinyl-based monomer copolymerizable with vinyl chloride is not particularly limited, for example,
Alkyl vinyl ester such as vinyl acetate, alkyl vinyl ether such as cetyl vinyl ether, α-monoolefin monomer such as ethylene or propylene, alkyl acrylate such as methyl acrylate, methacrylic acid such as methyl methacrylate Examples include alkyl esters.

Further, in the production method of the present invention, a suspending agent or a polymerization initiator conventionally used in a production method of a vinyl chloride polymer can be used.

Examples of the suspending agent include methyl cellulose, ethyl cellulose, hydroxyethyl cellulose,
Hydroxypropyl cellulose, water-soluble cellulose ethers such as hydroxypropylmethyl cellulose, water-soluble or oil-soluble partially saponified polyvinyl alcohol,
Examples include acrylic acid polymers and water-soluble polymers such as gelatin. These are used alone or in combination of two or more.

At the time of polymerization, various polymerization conditions such as an aqueous medium, vinyl chloride or a monomer mixture containing vinyl chloride, a suspending agent, a polymerization initiator, etc., a charging method, a charging ratio, a polymerization temperature and the like are set in the polymerization vessel. It may be performed in the same manner as the conventional one.

In the production method of the present invention, a chain transfer agent, a pH adjusting agent, an antioxidant, an antistatic agent, a cross-linking agent, a stabilizer, a filler, which is used for producing a vinyl chloride polymer, if necessary. It is also possible to add a scale inhibitor or the like.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

In the present invention, the method for measuring the tetrahydrofuran-insoluble gel content, the method for measuring the average molecular weight, the method for measuring the average degree of polymerization, the method for measuring the melt viscosity, and the method for measuring the mechanical strength were carried out by the methods described below.

<Measurement Method of Tetrahydrofuran-Insoluble Gel Content> 2 with tetrahydrofuran using a Soxhlet extractor
It was extracted for 2 hours, and the dry weight of the extraction residue remaining on the 350 mesh filter was calculated and calculated.

<Measurement Method of Average Molecular Weight> 0.03 g of vinyl chloride polymer was dissolved in 10 ml of tetrahydrofuran and filtered, and then converted into polystyrene by gel permeation chromatography (HLC (trademark) -8020, manufactured by Tosoh Corporation). The weight average molecular weight (Mw) and the number average molecular weight (Mn) of

Column: TSK-GEL ™ GMH
XL (manufactured by Tosoh Corporation) Standard polystyrene: A-2500, F-2, F-10,
F-40 (manufactured by Tosoh Corporation) Data processing device: SC-8010 (manufactured by Tosoh Corporation) <Average Degree of Polymerization> It was carried out according to the method prescribed in JIS K-6721.

<Measurement Method of Melt Viscosity> 1 mixture of Blend 1
The 1 mm-thick sheet obtained by kneading at 40 ° C. for 5 minutes was cut, and the pellets were cut according to the method specified in JIS K-7210.

Measuring instrument: Flow tester CFT-500
(Shimadzu) Temperature: 150 ° C. Load: 100 kgf Nozzle: 1 mmφ × 10 mm [Compound 1] Vinyl chloride polymer 100 parts by weight Dioctyl phthalate 50 parts by weight Tribasic lead sulfate 3 parts by weight Epoxidized soybean oil 3 parts by weight < Mechanical Strength Measuring Method> A tensile test was performed according to the method specified in JIS K-6723.

Example 1 100 parts by weight of vinyl chloride monomer, 150 parts by weight of deionized water, 0.1 part by weight of partially saponified polyvinyl alcohol, 0.04 part by weight of 2-ethylhexyl peroxydicarbonate were placed in a stainless steel polymerization vessel. , 2-mercaptoethanol (0.05 parts by weight) and diallyl phthalate (0.10 parts by weight) were charged, and polymerization was performed at a temperature of 60 ° C. The reaction was stopped when the conversion of polymerization reached 85%, and unreacted vinyl chloride monomer was recovered, dehydrated and dried to obtain a vinyl chloride polymer. The physical properties of the obtained polymer were evaluated by the methods described above. Table 1 shows the results.

The vinyl chloride polymers obtained by the following examples were also measured for their physical properties in the same manner as described above. The results are shown in Table 1 for the examples and in Table 2 for the comparative examples.

Example 2 In Example 1, the addition amount of diallyl phthalate was adjusted to 0.
A vinyl chloride polymer was obtained in the same manner as in Example 1, except that the amount of 2-mercaptoethanol was 15 parts by weight and the amount of 2-mercaptoethanol added was 0.015 parts by weight.

Example 3 A vinyl chloride polymer was obtained in the same manner as in Example 1 except that 0.10 parts by weight of diethylene glycol dimethacrylate was added instead of diallyl phthalate.

Example 4 In Example 1, the addition amount of diallyl phthalate was adjusted to 0.
A vinyl chloride polymer was obtained in the same manner as in Example 1 except that the amount of 2-mercaptoethanol was changed to 25 parts by weight and the amount of 2-mercaptoethanol added was changed to 0.05 parts by weight.

[0033]

[Table 1]

Comparative Example 1 A vinyl chloride polymer was obtained in the same manner as in Example 1 except that the polymerization temperature was changed to 57 ° C. and diallyl phthalate was not added.

Comparative Example 2 In Example 1, the addition amount of diallyl phthalate was adjusted to 0.
A vinyl chloride polymer was obtained in the same manner as in Example 1 except that the amount was 3 parts by weight and the polymerization temperature was 65 ° C.

Comparative Example 3 In Example 1, the addition amount of diallyl phthalate was adjusted to 0.
A vinyl chloride polymer was obtained in the same manner as in Example 1 except that the amount was 05 parts by weight.

Comparative Example 4 A vinyl chloride polymer was obtained in the same manner as in Example 1 except that 2-mercaptoethanol was not added.

Comparative Example 5 Polymerization was carried out in the same manner as in Example 1 except that the amount of 2-mercaptoethanol added was 0.15 parts by weight. However, the polymerization rate was remarkably reduced and the polymerization conversion rate did not reach 85%, so that a polymer worthy of evaluation could not be obtained.

[0039]

[Table 2]

[0040]

As described above, according to the method of the present invention, a vinyl chloride polymer excellent in meltability, mechanical strength and thermal stability can be obtained. Such a vinyl chloride polymer is It is suitable for module molding for large window frames and rotational molding for instrument panels.

Claims (1)

[Claims] 1. A suspension of a vinyl chloride monomer or a mixture of vinyl chloride-based monomers mainly comprising vinyl chloride in an aqueous medium, wherein a vinyl chloride monomer or vinyl chloride mainly comprising vinyl chloride is used. In the presence of 0.005-0.10 parts by weight of 2-mercaptoethanol per 100 parts by weight of the mixture of the system monomers, a monomer having two vinyl polymerizable double bonds in the molecule is added to vinyl chloride A tetrahydrofuran-insoluble gel content is 0, which is characterized by adding 0.10 to 0.25 part by weight to 100 parts by weight of a mixture of a monomer or a vinyl chloride-based monomer mainly composed of vinyl chloride, and copolymerizing. To 0.01% by weight, and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2.5 to 6.0.