JPH02279708A - Polymerization of vinyl chloride monomer - Google Patents

Abstract

PURPOSE:To obtain a polymer which is odorless and excellent in heat resistance, especially colorlessness, below a specified low temperature by using a specified polymerization initiator in the polymerization of a vinyl chloride monomer. CONSTITUTION:2,5-Bis(phenoxyacetylperoxy)-2,5-dimethyl-3-hexane is used as a polymerization initiator in the production of a polymer of an average degree of polymerization >=1500 by polymerizing a vinyl chloride monomer at a polymerization temperature <=50 deg.C. When compared with a process performed by using a conventional initiator (e.g. acetylcyclohexylsulfonyl peroxide), the process performed by using the above polymerization initiator is advantageous in that the obtained polymer is odorless and excels in heat stability, especially colorlessness, the polymerization activity is high, the rate of polymerization is high, and therefore the polymerization yields are good.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention uses a specific polymerization initiator when polymerizing vinyl chloride monomers, thereby achieving high yields at a polymerization temperature of 50°C or less. This invention relates to a method for polymerizing vinyl chloride monomers, which can yield a polymer with a high degree of polymerization at a low temperature, and which has improved thermal stability, especially colorability, and is odorless. It is something.

(Prior art) In the industry, vinyl chloride polymers with an average degree of polymerization of 6
Those with a rating of 00 to 1,500 are called general products, and those with a rating of 1,500 or more are called high polymerization products. It is known that products with a high degree of polymerization are particularly superior in physical properties such as mechanical strength, thermal stability, dimensional stability, and cold resistance compared to general products. Furthermore, in the case of soft polyvinyl chloride produced by using a plasticizer in polyvinyl chloride, the rubber elasticity can be improved as the degree of polymerization increases.

As shown in Table 1, the average degree of polymerization of polyvinyl chloride is determined by its polymerization temperature, so in order to obtain such high degree of polymerization polyvinyl chloride,
The polymerization must be carried out at relatively low temperatures below °C.

Table 1 Polymerization temperature (C) Average degree of polymerization For this reason, a polymerization initiator that is sufficiently active even at low temperatures is desired.

Conventionally, when polymerizing vinyl chloride monomers, diisobutyryl peroxide (hereinafter abbreviated as IBPO) and acetylcyclohexylsulfonyl peroxide (hereinafter abbreviated as ACSP) have been used as low-temperature active polymerization initiators such as those mentioned above. ) (JP-A-40-16795), cumyl peroxyneodecanoate (hereinafter abbreviated as CHD) (JP-A-58-120611), and the like are known to be used. It is also known that t-octyl peroxyphenoxy acetate (hereinafter abbreviated as OPA) (Japanese Unexamined Patent Publication No. 15990/1982) is active at low temperatures.

(Problems to be Solved by the Invention) The polymerization methods using IBPO1^C5PSCND and OPA as polymerization initiators each have their own problems.

That is, IBPO is very unstable in water and decomposes on contact with water, so the polymerization activity is not sustainable, resulting in a low polymer yield. In addition, ACSP has hygienic problems due to decomposition products and poor thermal stability such as coloring of the obtained polymer. Furthermore, CND had the disadvantage of having a characteristic odor of the polymer due to decomposition products. Further, although OPA has almost the same activity as CND, the compound itself has a very strong unpleasant odor, which poses a problem for industrial use.

Furthermore, all of these polymerization initiators have the disadvantage that they are extremely unstable with respect to temperature and are very dangerous in handling.

(Means for Solving the Problems) As a result of long-term research into the problems of the above-mentioned conventional methods, the present inventors found that by using a specific polymerization initiator, a good yield ( Highly polymerized polyvinyl chloride can be obtained, and the obtained polymer has excellent thermal stability, especially colorability, and is odorless. Furthermore, this polymerization initiator is extremely safe in terms of storage stability. After confirming this, the present invention was completed.

That is, the present invention uses 2,5-bis(phenoxyacetylperoxy)- as a polymerization initiator when obtaining a highly polymerized product by polymerizing vinyl chloride monomers at a polymerization temperature of 50°C or lower.
This is a method for polymerizing vinyl chloride, characterized by using 2,5-dimethyl-3-hexyne.

The vinyl chloride monomer used in the present invention refers to vinyl chloride monomer alone or a mixture of vinyl chloride monomer and a monomer copolymerizable therewith.

Other vinyl monomers copolymerizable with the vinyl chloride monomer used in the present invention include, for example, ethylene, acetic acid,
vinyl, vinylidene chloride, styrene, acrylic esters, etc.

The specific polymerization initiator used in the present invention can be obtained, for example, as follows.

That is, 2,5-dimethyl-2,5-dihydroperoxy-3-hexyne and phenoxyacetic acid halide are reacted using sodium hydroxide, potassium hydroxide, or an amine such as pyridine as a catalyst in the same manner as a normal peroxyester. Obtained under conditions.

That is, it can be synthesized using an aromatic hydrocarbon (for example, toluene, ethylbenzene) as a solvent, or it can be diluted and used after synthesis. The reaction temperature is -10°C
~30°C.

The amount of the polymerization initiator used in the present invention can be selected as appropriate, but it is usually about 0.001 to 2 parts by weight in terms of pure product per 100 parts by weight of the vinyl chloride monomer charged. Preferably it is 0.01 to 1 part by weight.

If the amount is less than 0.001 parts by weight, the polymerization rate will be slow. Moreover, if it exceeds 2 parts by weight, it becomes difficult to control the polymerization reaction and the physical properties of the resulting polymer deteriorate, which is not preferable.

The specific polymerization initiator used in the present invention can be used alone or in combination with conventionally used Ike's peroxydicarbonate, diacyl peroxide, peroxyester, or azobis-based polymerization initiator. It is.

Peroxides that can be used in combination include peroxydicarbonates such as bis(2-ethylhexyl) peroxydicarbonate and diisopropyl peroxydicarbonate, and diacylperoxides such as IBPo, 3. 5. Peroxy esters, such as 5-trimethylhexanoyl peroxide, are e.g.
-octylperoxyneodecanoate, t-butylperoxypivale-1, etc.

Further, examples of the azobis-based polymerization initiator include abbisisobutyronitrile and azobis-2°4-dimethylvaleronitrile.

The polymerization method used in the present invention may be conventional suspension polymerization or emulsion polymerization.

The polymerization temperature in the present invention is not particularly limited as long as it is selected to obtain a highly polymerized product, but the average degree of polymerization is 15
The lower limit is not particularly limited, with the upper limit being 50"C, the temperature at which 0.
The temperature range is 0 to 50°C.

(Effects of the Invention) The present invention, which uses a specific polymerization initiator, has the following characteristics.

That is, conventional polymerization initiators (e.g. ACSP, CND
), the resulting polymer has no odor (it is superior in terms of thermal stability, especially no coloration).Also, compared to methods using conventional polymerization initiators (e.g. IBPO), the polymerization activity is lower. The sustainability of the polymerization is high, and the polymerization rate is high.Therefore, it is superior in that it results in a high polymer yield.Furthermore, the specific polymerization initiator used in the present invention has a higher polymerization rate than conventional polymerization initiators (for example, OPA). Since it has almost no odor, it can be used industrially without any problem.

Furthermore, the specific polymerization initiator used in the present invention is superior to conventional polymerization initiators in that it is extremely safe in terms of storage stability. That is, the specific polymerization initiator used in the present invention shows no decrease in purity for one month or more at a storage temperature of 0°C. On the other hand, the above polymerization initiator is IBPO at storage temperature O''C.
Purity decreased by 2.5% in 48 hours, ACSP and CND decreased by 1.8% and 5.5% in one month, respectively, and AC
SP was colored pale yellow.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

Reference example (2,5-bis(phenoxyacetylperoxy)-2
, 5-dimethyl-3-hexyne) In a 300 mJ2 four-bottle flask equipped with a stirrer, 89.9 g (0.32 mol) of 20% aqueous potassium hydroxide solution and 98.9 g (0.32 mol) of 20% aqueous potassium hydroxide solution were added.
%2.5-dimethyl-2,5-dihydroperoxy-3
- 17.6 g (0.1 mol) of hexine was added and stirring was started. Furthermore, as a wetting agent, we use a dioctyl sodium sulfosuccinate surfactant (trade name: ``Rapidul B-8'').
After adding 0.5 g of 0.1 NOF), the internal temperature was reduced to 1
Phenoxyacetic acid chloride 37.5 while keeping at 5°C
g (0.22 mol) was added dropwise over 6 minutes.

After the addition, the reaction mixture was stirred for an additional hour at a temperature of 15°C. Next, add 100g of cold water to the solution and
After stirring for a minute, white crystals were removed by suction filtration. The crystals were washed with 100 g of a 5% aqueous sodium hydroxide solution and further washed three times with 1200 g of cold water to obtain 52 g of a crude product as white fine powder crystals. The crystals were dissolved in 180 g of methylene chloride, the water contained therein was separated, and the crystals were further dehydrated with anhydrous sodium sulfate.

This methylene chloride solution was poured into 350 cj2 of petroleum ether with stirring, and the precipitated white crystals were separated by suction filtration.

The crystals were further washed three times with 100 mj2 of petroleum ether and dried to obtain 27.1 g of white crystals. As a result of analyzing this crystal by IR and NMR, 2,5-bis(phenoxyacetylperoxy)-2,5=dimethyl-3
- Confirmed to be hexine.

The amount of active oxygen in this solid was measured and found to be 7.12%. Calculated purity 98.5%, yield 60.3 mol%
Met. The melting point of this solid was measured to be 72°C. Furthermore, the odor of this solid was investigated, but there was almost no odor.

Example 1 In a stainless steel autoclave with a capacity of 400 ml, 200 s of ion-exchanged water and 0.1 ml of polyvinyl alcohol were added.
parts by weight were added and dissolved. Next, the 2 obtained in the reference example
, 5-bis(phenoxyacetylperoxy)-2,5
-0.15 mmol of dimethyl-3-hexyne (hereinafter abbreviated as 25PA') was added, cooled to -80°C or lower, and 100 parts by weight of vinyl chloride monomer was added. After the space in the autoclave was sufficiently replaced with nitrogen gas, it was sealed tightly. It was immersed in a constant temperature water bath kept at 45°C for 8 hours to polymerize. Stir the autoclave in a water tank at 32r
This was done by rotating with p-. After polymerization, it is cooled, unreacted vinyl chloride monomer is removed, and the resulting white powder is heated twice at 100mj! After washing with water and drying under vacuum, the yield of vinyl chloride polymer from 0 weight was 85%, and the average degree of polymerization was 2520.

As a thermal stability test for the obtained vinyl chloride polymer, the coloring test shown below was conducted, and at the same time, the odor was also investigated. The respective results are shown in Table-2 and Table-3.

[Colorability test] 100 parts by weight of vinyl chloride polymer, 2.5 parts by weight of dibutyltin maleate, 80 parts by weight of dioctyl phthalate as a plasticizer
Parts by weight were mixed and kneaded for 10 minutes on a roll at 160°C. A sheet with a thickness of 11 was taken out and the degree of coloration of the sheet was visually observed.

Example 2.3 Polymerization of vinyl chloride monomers was carried out in the same manner as in Example 1, except that the amount of 25PA used as a polymerization initiator and the polymerization temperature were changed. These results are shown in Table 2 and Table 3, respectively.

Example 4 Polymerization of vinyl chloride monomer was carried out according to Example 1, except that the vinyl chloride monomer was changed to 90 parts by weight of vinyl chloride monomer and 10 parts by weight of vinyl acetate monomer. These results are shown in Table 2 and Table 3, respectively.

Comparative Examples 1 to 3 Except for using conventional acetyl cyclohexyl sulfonyl peroxide (ACSP), cumyl peroxy neodecanoate (CND), and diisobutyryl peroxide (IBPO) as polymerization initiators, Table- Polymerization of vinyl chloride monomer was carried out according to Example 1 under the conditions shown in 2. These results are shown in Table-2 and Table-3, respectively.
Shown below.

Table 3 As is clear from Tables 2 and 3, in the conventional method using a polymerization initiator, the heat resistance (
Either the coloring property is poor or there is an odor.
Alternatively, there are problems such as low yield even if the coloring property and odor are good, whereas the method of the present invention satisfies all of these.

The absence of odor is desirable from the viewpoint of the working environment during molding and processing.

Claims (1)

[Claims] 1. 2,5-bis(phenoxyacetylperoxy)-2,5-dimethyl is used as a polymerization initiator when polymerizing vinyl chloride monomers at a polymerization temperature of 50°C or lower to obtain a polymer with an average degree of polymerization of 1500 or higher. - A method for polymerizing vinyl chloride monomers, characterized by using 3-hexyne.