JPH09278815A - Method of polymerization of vinyl chloride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high conversion of a polyvinyl chloride which has good initial coloration and thermal stability, scarcely forms fisheyes, and has a good capacity of absorbing a plasticizer by using specified polymerization initiators in combination. SOLUTION: A blend of polymerization initiators comprising a cumyl peroxyneopentanoate represented by the formula (wherein R<1> , R<2> and R<3> are each a 1-3C alkyl, with the total number of carbon atoms of these groups being 5) and an organic peroxide having a 10-hr half-life temperature of 33-62 deg.C at a weight ratio of (9:1) to (1:9) is added in an amount of 0.001-1 pt.wt. to 100 pts.wt. vinyl chloride monomer to polymerize the monomer at 40-80 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polymerization method for polymerizing a vinyl chloride monomer to obtain a vinyl chloride (co) polymer having good physical properties. More specifically, by polymerizing a mixture of vinyl chloride alone or another monomer copolymerizable therewith with a specific polymerization initiator, initial colorability and thermal stability are good, and fish eye The present invention relates to a vinyl chloride polymerization method capable of obtaining a polymer having a small amount and a good plasticizer absorbability with high productivity.

[0002]

2. Description of the Related Art Polyvinyl chloride is a thermoplastic resin having excellent physical properties and is used in many fields as a material for hard and soft resins. Among them, polyvinyl chloride having an average degree of polymerization of 1500 or less, which is produced by polymerizing a monomer at a relatively high temperature such as 40 to 80 ° C, has suitable properties as a film, a sheet and the like. . recent years,
Polyvinyl chloride manufacturers tend to increase the amount of polymerization initiator used in order to shorten the polymerization time for the purpose of improving productivity. However, when a large amount of the polymerization initiator is used, it is known that the physical properties of the polymer are adversely affected depending on the type of the polymerization initiator used. For example, the initial coloring property and thermal stability of the obtained polyvinyl chloride are known. However, there was a problem that the product value declined. In order to solve this, JP-A-7-292018 discloses that by using a combination of t-alkylperoxy neoheptanoate and an organic peroxide having a 10-hour half-life temperature of 33 to 62 ° C. It is disclosed that a polyvinyl chloride having good stability can be obtained. Further, Japanese Patent Publication No. 59-14881 discloses a method for polymerizing polyvinyl chloride using peroxyneoheptanoate, and Japanese Patent Laid-Open No. 58-120611 discloses a method for polymerizing polyvinyl chloride using α-cumylperoxyneodecanoate. A polymerization method is disclosed.

[0003]

However, although the method described in Japanese Patent Application Laid-Open No. 7-292018 provides polyvinyl chloride having good physical properties, there is still room for improvement in the polymerization conversion rate. . In addition,
The method described in Japanese Patent No. 14481 did not sufficiently improve the polymerization conversion rate, and did not improve the physical properties of the obtained polyvinyl chloride at all. In addition, JP-A-58-120
In the method described in Japanese Patent No. 611, although the initial colorability is improved, other physical properties, that is, thermal stability,
There was still room for improvement in fish eye and plasticizer absorbency. Therefore, there has been a demand for a new polymerization initiator capable of obtaining a polymer having good physical properties and having a high polymerization conversion rate and capable of achieving improvement in productivity.

The object of the present invention is to meet this demand, and by using a specific polymerization initiator in combination, the initial colorability and heat stability are good, the fish eyes are small, and the plasticizer absorbability is small. It is an object of the present invention to provide a polymerization method capable of obtaining good polyvinyl chloride at a high polymerization conversion rate.

[0005]

As a result of researching the above problems, the present inventors have found that the object can be achieved by using a specific polymerization initiator in combination for the polymerization of vinyl chloride, and have completed the present invention. did.

That is, the present invention uses (A) the general formula (1) as a polymerization initiator.

Embedded image (In the formula, R ¹ , R ² and R ³ are each an alkyl group having 1 to 3 carbon atoms, and the total carbon number of R ¹ , R ² and R ³ is 5.) Cumylperoxy neohepta Noate and (B) an organic peroxide having a 10-hour half-life temperature of 33 to 62 ° C. in a weight ratio of (A) to (B) of 9: 1 to
The present invention relates to a method for polymerizing vinyl chloride, which comprises using a 1: 9 ratio and polymerizing a vinyl chloride monomer at 40 to 80 ° C.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be sequentially described below. The vinyl chloride monomer used in the present invention means a vinyl chloride monomer alone or a mixture with another monomer copolymerizable therewith. Examples of the other monomer copolymerizable with the vinyl chloride monomer include ethylene, vinyl acetate, vinylidene chloride, stellene, and acrylic acid esters.

The raw material neoheptanic acid constituting the cumylperoxy neoheptanoate in the present invention is a carbon of the tertiary carboxylic acids in which the α-carbon atom of the carboxylic acid is completely replaced by an alkyl group. The isomers of carboxylic acid whose number is 7, namely 1,1-dimethylpentanoic acid, 1-ethyl-1-methylbutanoic acid and 1,1,
Cumyl peroxyneoheptanoate used in the present invention is a mixture of 2-trimethylbutanoic acid and is derived from a mixture of acid isomers having these skeletons.

In the present invention, the above-mentioned (A) cumyl peroxyneoheptanoate and (B) 1 are used as polymerization initiators.
The 0-hour half-life temperature (hereinafter abbreviated as T10) is 33.
Used in combination with an organic peroxide that is ~ 62 ° C. Here, T10 means a temperature at which the concentration of the organic peroxide measured at a concentration of 0.1 mol / liter in benzene becomes a half concentration in 10 hours.

As the above organic peroxide (B), for example,
As a peroxy ester, t-butyl peroxy neodecanoate (T10: 47 ° C.), t-hexyl peroxy neodecanoate (T10: 45 ° C.), 1-cyclohexyl-1-methylethyl peroxy neodecanoate. (T10: 41 ° C.), t-octyl peroxy neodecanoate (T10: 41 ° C.), cumyl peroxy neodecanoate (T10: 37 ° C.), α, α′-bis (neodecanoylperoxy) diisopro Bill benzene (T
10: 36 ° C.), t-butylperoxypivalate (T
10: 55 ° C.), t-hexyl peroxypivalate (T10: 53 ° C.) and the like.

As dialkyl peroxydicarbonates, bis (2-ethylhexyl) peroxydicarbonate (T10: 43 ° C.), ethoxyethyl peroxydicarbonate (T10: 43 ° C.), diisopropyl peroxydicarbonate (T10: 41 ° C.) ) And the like.

Further, as the diacyl peroxide,
Isobutyryl peroxide (T10: 33 ° C), 3,
5,5-Trimethylhexanoyl peroxide (T1
0: 60 ° C.), lauroyl peroxide (T10: 62)
C), n-octanoyl peroxide (T10: 62
° C).

Particularly preferred are t-butyl peroxy neodecanoate, t-hexyl peroxy neodecanoate, t-octyl peroxy neodecanoate, bis (21-ethylhexyl) peroxydicarbonate and isobutyrate. Examples thereof include ryl peroxide and lauroyl peroxide. One or more of these organic peroxides are appropriately selected depending on the polymerization conditions such as polymerization temperature and polymerization time, and the intended use of the obtained polyvinyl chloride.

In the present invention, when the T10 of the organic peroxide to be combined is less than 33 ° C., the polymerization rate decreases, and
If it exceeds, it is not preferable because the control of the polymerization reaction becomes difficult.
The blending ratio and the amount of both components of the organic peroxides (A) and (B) used in combination as the polymerization initiator may be appropriately determined according to the reaction conditions. The blending ratio is a weight ratio of organic peroxide (A) :( B) = 9: 1 to 1: 9.
If the blending ratio exceeds this range, the difference in the reaction rate between the early and late stages of the polymerization reaction becomes large, making it difficult to control the reaction and deteriorating the physical properties of the resulting polymer, which is not preferable.

The addition amount of the polymerization initiator used in the present invention is 0.001 to 1 part by weight, preferably 0.00, 1 part by weight based on 100 parts by weight of the vinyl chloride monomer charged.
5 to 0.5 parts by weight. If the amount is less than 0.001 part by weight, the polymerization rate tends to be slow, and if it exceeds 1 part by weight, it is difficult to control the polymerization reaction and the physical properties of the obtained polymer are deteriorated.

The polymerization method used in the present invention may be ordinary suspension polymerization or emulsion polymerization. The polymerization temperature is 40 to 80 ° C, preferably 50 to 65 ° C.
If the polymerization temperature is less than 40 ° C, the polymerization time will be longer,
If it exceeds, the life of the polymerization initiator is shortened and it becomes difficult to reach a high polymerization conversion rate.

[0017]

EFFECTS OF THE INVENTION Since the present invention uses a specific polymerization initiator, it has excellent initial colorability and thermal stability, less fish eyes, and better plasticizer absorbability than those using conventional polymerization initiators. Polyvinyl chloride can be obtained with high productivity. Further, this polyvinyl chloride has less generation of fish eyes and has good plasticizer absorbability, so that the time required for processing the soft product can be shortened.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples. The abbreviations of the polymerization initiators used in Examples and Comparative Examples are shown below. CNH: cumyl peroxyneoheptanoate (T1
0: 42 ° C.) CND: cumyl peroxyneodecanoate (T10:
36 ° C.) BND: t-butylperoxy neodecanoate (T1
OND: t-octyl peroxy neodecanoate (T: 0: 47 ° C.)
10: 40 ° C.) IBPO: isobutyryl peroxide (T10: 33
C) LPO: lauroyl peroxide (T10: 62 ° C) ONH: t-octylperoxyneoheptanoate (T10: 44 ° C) BNH: t-butylperoxyneoheptanoate (T
10: 50 ° C)

Example 1 150 ml of ion-exchanged water and 0.1 g of polyvinyl alcohol were placed and dissolved in a stainless steel autoclave having a volume of 400 ml. Next, 0.030 g of CNH in terms of pure product and 0.030 g of CND in terms of pure product are added, cooled to −80 ° C. or lower, and 100 g of vinyl chloride monomer is added.
Was added. The space in the autoclave was thoroughly replaced with nitrogen gas, and the container was sealed. It was immersed in a constant temperature water bath kept at 50 ° C. for 6 hours for polymerization. The stirring was performed by rotating the autoclave in a water tank at a speed of 32 rpm. After the polymerization, the reaction mixture was cooled, unreacted vinyl chloride monomer was removed, the obtained white powder was washed twice with 100 ml of water, and then dried under vacuum. Experiments under the same conditions were conducted in parallel using three autoclaves, and the polymerization conversion rate was obtained from the average value of dry weight obtained in each experiment. as a result,
The conversion was 85.7% and the average degree of polymerization was 1460.

The physical properties of the obtained vinyl chloride polymer were tested on the following items. The respective results are shown in Table 1 and Table 2. [Initial Coloring Property] 100 parts by weight of a vinyl chloride polymer, 2.5 parts by weight of dibutyl tin malate as a stabilizer, and 80 parts by weight of dioctyl phthalate as a plasticizer are mixed at 160 ° C.
The mixture was kneaded on the roll for 10 minutes, and a sheet having a thickness of 1 mm was taken out. From the degree of coloration of the sheet visually, it was shown as follows. ○: Not colored △: Colored slightly yellow

[Thermal Stability Test] 50 parts by weight of a vinyl chloride polymer, 20 parts by weight of dioctyl phthalate, 1 part by weight of a stabilizer (metal soap of barium / zinc system), and 1 part by weight of an epoxy system stabilizer were mixed to prepare 160 The mixture was kneaded for 5 minutes on a roll at 0 ° C., and a 0.5 mm thick sheet was taken out. This sheet was heated in a gear oven at 190 ° C., and the coloring of the sheet was observed with time, and the thermal stability was shown as follows from the time when the sheet began to turn black. ○: Blackening time 100 minutes or more △: Blackening time 80 to 100 minutes

[Fish Eye] Vinyl Chloride Polymer 50
25 parts by weight of dioctyl phthalate, 2 parts by weight of a stabilizer (metal soap of barium / zinc system) and 3 parts by weight of pigment are added to and mixed with each other, and then the mixture is kneaded with a roll at 140 ° C. for 5 minutes to obtain a thickness. The number of fish eyes recognized in the sheet 100 having a thickness of 0.3 mm is shown.

[Plasticizer absorbability] 20 parts by weight of dioctyl phthalate as a plasticizer was added to 10 parts by weight of a vinyl chloride polymer, and the mixture was allowed to stand for 1 hour. Then, the powder-absorbed plasticizer was separated and removed by a centrifuge to obtain a polymer. The amount of plasticizer absorbed is given in% by weight.

[0024]

[Table 1]

[0025]

[Table 2] Note) F. E: Fish eye

Examples 2 to 5 Vinyl chloride monomers were polymerized in the same manner as in Example 1 except that the polymerization initiators shown in Table 1 were used and the polymerization temperatures shown in Table 1 were used.
The test results of the obtained polymer are shown in Table 1 and Table 2 as in Example 1, respectively.

Example 6 Same as Example 1 except that the vinyl chloride monomer was changed to a mixture of 90 parts by weight of vinyl chloride monomer and 10 parts by weight of vinyl acetate monomer and the polymerization temperature was set to 60 ° C. Then, polymerization was carried out.
The test results of the obtained copolymer are shown in Tables 1 and 2.

Comparative Examples 1 to 5 As polymerization initiators, the polymerization initiators shown in Table 1 were used.
Polymerization of a vinyl chloride monomer was carried out in accordance with Example 1 under the conditions shown in. The test results of the obtained polymer are shown in Table 1 and Table 2, respectively.

As is clear from Table 1, initial coloring is achieved by using the specific polymerization initiator of the present invention in the polymerization of a vinyl chloride monomer or a vinyl chloride monomer and a monomer copolymerizable therewith. It is possible to obtain polyvinyl chloride with excellent polymerization properties and heat stability, less fish eyes, and good plasticizer absorbency at a high polymerization conversion rate. On the other hand, when the conventional polymerization initiator is used (Comparative Examples 1 to 6), the obtained polyvinyl chloride has many physical properties, particularly fisheyes, and the plasticizer absorbency is poor, and the polymerization conversion rate is low.

Claims (1)

[Claims] 1. A general formula (1) as a polymerization initiator: (In the formula, R ¹ , R ² and R ³ are each an alkyl group having 1 to 3 carbon atoms, and the total carbon number of R ¹ , R ² and R ³ is 5.) Cumylperoxy neohepta Noate and (B) an organic peroxide having a 10-hour half-life temperature of 33 to 62 ° C. in a weight ratio of (A) to (B) of 9: 1 to
A method for polymerizing vinyl chloride, which comprises using 1: 9 and polymerizing a vinyl chloride monomer at 40 to 80 ° C.