JP2000302805A - Manufacture of vinyl chloride resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a vinyl chloride resin causing little scale adhesion during polymerization, excellent in workability and thermal stability, and without deterioration in quality. SOLUTION: In suspension polymerization of vinyl chloride monomer, or a mixture of a monomer capable of copolymerizing with vinyl chloride and vinyl chloride in an aq. medium, a suspension dispersant comprising a partially saponified polyvinyl acetate (a) with a saponification degree of 70-85% and an avereage polymerization degree of 1,500-2,500, a partially saponified polyvinyl acetate (b) with a saponification degree of 33-70% and an average polymerization degree of 200-1,000, and an org. acid aq. solution of chitosan (C)is used based on 100 pts.wt. vinyl chloride monomer, or the mixture of a monomer capable of copolymerizing with vinyl chloride and vinyl chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a vinyl chloride resin and a resin composition thereof. More specifically, the present invention relates to a vinyl chloride resin having an effect of preventing scale during polymerization and having excellent processability and thermal stability. The present invention relates to a method for producing a resin.

[0002]

2. Description of the Related Art Vinyl chloride resins are inexpensive and have an excellent balance of quality. Therefore, they are thermoplastic resins used in various fields such as hard fields and soft fields. Examples include pipes and joints, window frames, industrial transparent plates, films, etc., and in the field of soft materials, electric wire coatings, wrap films, sheets, and the like.

[0003] A vinyl chloride resin as a material is a general-purpose resin which is indispensable to be inexpensive. However, various characteristics are required also in terms of performance. Plasticizer absorption and suppression of fish eyes.

On the other hand, in the field of hard applications, good workability and thermal stability when processing into various molded articles, and good basic physical properties such as tensile strength and impact strength after molding are required. Various attempts have been made to improve these required characteristics, and many can be seen in the techniques disclosed so far. For example, JP-A-9-27896
JP-A-10-1584 discloses a method of adding a methyl methacrylate-butadiene-styrene copolymer or chlorinated polyethylene to a vinyl chloride resin in order to improve impact resistance and molding processability. A method of adding a calcium compound, a zinc compound, an epoxidized vegetable oil, a β-diketone compound and an ester compound to a vinyl chloride resin in order to improve thermal stability and processability;
Japanese Patent Application No. 17744 discloses a method of blending a chlorinated polyolefin and / or a vinyl ester-ethylene copolymer with a vinyl chloride resin in order to improve moldability.

However, all of these methods contain various reinforcing agents and additives, and generally require a large amount of various reinforcing agents and additives. Furthermore, when polymerizing polyvinyl chloride resin, various scales are used to prevent scale from adhering to the inner wall of the polymerization vessel, the inner wall of the monomer reflux unit, and the inner wall of the piping in the system, causing deterioration in quality and poor heat removal during polymerization. It is polymerized by applying a scale inhibitor.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and is a vinyl chloride resin having little scale adhesion during polymerization, excellent in processability and thermal stability, and having no deterioration in physical properties. An object of the present invention is to provide a method for producing the same.

[0007]

DISCLOSURE OF THE INVENTION The present inventors have developed a method for producing a vinyl chloride resin which has little scale adhesion during polymerization and has excellent properties required for quality, that is, excellent processability and thermal stability and has no deterioration in physical properties. As a result of intensive studies on vinyl chloride monomer or a mixture of vinyl chloride monomer and a monomer copolymerizable with vinyl chloride monomer, a specific dispersion The present inventors have found that a vinyl chloride resin composition excellent in required characteristics can be obtained without any problem by using a combination of the agents, and the present invention has been accomplished.

That is, the present invention relates to a method for preparing a vinyl chloride monomer or a mixture of a monomer copolymerizable with the vinyl chloride monomer and a vinyl chloride monomer in suspension polymerization in an aqueous medium. Vinyl monomer, or a mixture of a monomer copolymerizable with a vinyl chloride monomer and a vinyl chloride monomer (hereinafter, referred to as
(Referred to as “vinyl chloride monomer”), (a) a saponification degree of 70 to 85% and an average polymerization degree of 15
(B) partially saponified polyvinyl acetate which is from 00 to 2500;
Saponification degree is 33-70%, average polymerization degree is 200-1000
Using a partially saponified polyvinyl acetate and an organic acid aqueous solution of (c) chitosan (claim 1).
The above (a) was used as a suspending and dispersing agent in an amount of 0.0
2 to 0.08 parts by weight, 0.01 to 0.05 of the above (b)
2. The method for producing a vinyl chloride resin according to claim 1, wherein 0.005 to 0.2 parts by weight of (c) is used, and the vinyl chloride monomer 1 is used.
With respect to 00 parts by weight, the above-mentioned (a)
(B) and (c) are calculated as follows: (a) / (b) = 1/1 to 5 /
And the total number of copies of (a) + (b) is 0.02-0.
08 parts by weight, (a + b) / (c) = 1/10 to 10/1
(C) is used in an amount of 0.005 to 0.2 parts by weight in the ratio of (3).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, when a vinyl chloride monomer is subjected to suspension polymerization in an aqueous medium, (a) a saponification degree is used as a suspending / dispersing agent with respect to the vinyl chloride monomer. 70-85
%, Partially saponified polyvinyl acetate having an average degree of polymerization of 1500 to 2500, (b) partially saponified polyvinyl acetate having a saponification degree of 33 to 70% and an average degree of polymerization of 200 to 1000,
And (c) a method for producing a vinyl chloride resin, which comprises using an aqueous solution of chitosan in an organic acid.

For the production of the vinyl chloride resin used in the present invention, it is essential to use these three dispersants in combination. However, even if an aqueous polymer solution serving as a suspension stabilizer such as methylcellulose or polyethylene oxide is added in addition to the above three dispersants, the characteristics of the present invention are not lost.

(A) is a method for producing a vinyl chloride resin,
It may be referred to as the most commonly used partially saponified polyvinyl acetate (hereinafter referred to as "PVA"), and has extremely high polymerization stability. The saponification degree of (a) is 70 to 85%. If the saponification degree is less than 70%, the surface activity becomes too strong and it becomes difficult to dissolve in water, so that it is difficult to handle.
If it exceeds 5%, the polymerization reaction is difficult to proceed stably due to insufficient surface activity. The average polymerization degree of this (a) is 1500 to 25
00, preferably 1800 to 2200. If the average degree of polymerization is less than 1500, it is necessary to increase the amount used in order to allow the polymerization reaction to proceed stably, and as a result, the thickness of the resin surface dispersant film becomes too thick. On the other hand, when the average degree of polymerization is 2
If it exceeds 500, the thickness of the resin surface dispersant film becomes too thick even if the amount used is small. Thus, neither case is preferred.

The amount of (a) added is 10
It is preferable to use 0.02 to 0.08 parts by weight with respect to 0 parts by weight. If the amount is less than 0.02 parts by weight, the polymerization cannot proceed stably, and if it exceeds 0.08 parts by weight, the resulting dispersant film on the resin surface becomes thick and impairs the processability.

(B) can be said to be a PVA suitable for making the inside of the resin highly porous in order to improve the processability, but it is very difficult to progress the polymerization reaction stably by itself,
It is necessary to use PVA as in (a) in combination. The saponification degree of (b) is 33 to 70%. Saponification degree 3
If it is less than 3%, the solubility in water or the swelling property is so reduced that the effect of increasing the porosity inside the resin is hardly exhibited. If the degree of saponification exceeds 70%, the solubility in the monomer is substantially lost, and the effect of making the inside of the resin porous cannot be expected. The average degree of polymerization of this (b) is 200
１０００1000, preferably 300-700. If the average degree of polymerization is less than 200, the solubility in the monomer is too large, so that the initially formed monomer oil droplets become unstable, and the polymerization reaction cannot proceed normally. If the average degree of polymerization exceeds 1,000, on the contrary, the solubility in the monomer is too low, and the porosity inside the formed resin cannot be increased.

The amount of (b) to be added is as follows.
It is preferable to use 0.01 to 0.05 parts by weight based on 00 parts by weight. If this amount is less than 0.01 part by weight, the porous effect inside the resin will not be exhibited, and if it exceeds 0.05 part by weight, the dispersibility of the oil droplets of the monomer will be too high to stabilize the polymerization. It is difficult to progress.

The organic acid aqueous solution of chitosan (c) is PV
The effect of suppressing the adhesion of monomer oil droplets covered with A etc. due to collision (oil droplet protection) and the occurrence of monomer oil droplets colliding with the inner wall of the polymerization vessel, breaking and adhering The effect of reducing the scale to be performed is shown. The amount of (c) added is
0.005 to 100 parts by weight of the vinyl chloride monomer
It is preferable to use 0.2 to 0.2 parts by weight. If the amount is less than 0.005 parts by weight, the polymerization reaction does not proceed stably and abnormal polymerization occurs. If the amount exceeds 0.2 parts by weight, the particle size of the obtained resin becomes extremely small. This is because the dispersant (c) has almost no surface active ability unlike other dispersants.
It is also characterized by a high molecular weight and therefore a very high viscosity, exhibiting a remarkable thickening effect. It is localized on the water side of the water / monomer oil droplet interface and has a very high oil droplet protection power. In addition, due to the remarkably high viscosity, the effect of suppressing fusion is exhibited in a very small amount. This effect makes it possible to greatly reduce the amount of other dispersants used, in particular the (a) and (b)
Reducing the amount of the dispersant as described above is beneficial because it leads to a thinner dispersant film on the surface.

The most preferred organic acid used in the aqueous solution of chitosan in organic acid is acetic acid. The aqueous solution of the organic acid used for the preparation of the present chitosan aqueous solution preferably has a concentration of 0.1 to 1.0%, and the concentration of chitosan depends on the solubility in the organic acid aqueous solution. 0.0% by weight. From the point of handling at the time of preparation, 0.03 to 1.0
An aqueous solution of acetic acid in weight% chitosan is particularly preferred.

The above two types of suspending and dispersing agents (a) and (b) are used in an amount of (a) / 100 parts by weight of the vinyl chloride monomer.
(B) = A total of (a) + (b) in a ratio of 1/1 to 5/1 is 0.02 to 0.08 parts by weight, preferably 0.04 parts by weight.
Used at で 0.07 parts by weight. (A) / (b) ratio is 1
If it is less than / 1, polymerization cannot proceed stably,
If the ratio exceeds 5/1, the thickness of the dispersant film on the surface of the resin to be formed becomes too thick or the particle diameter becomes too small, which adversely affects the processability.

If the total number of (a) + (b) is less than 0.02 parts by weight, the polymerization reaction cannot proceed stably.
If the amount exceeds 0.08 parts by weight, the resulting dispersant film on the resin surface becomes too thick, which adversely affects the processability. Further, with respect to 100 parts by weight of the vinyl chloride monomer, (c) was added to the above two kinds of suspending dispersants at a ratio of (a + b) / (c) = 1/10 to 10/1, and 0.005 to 0.005. Use 0.2 parts by weight. (A +
When the ratio of b) / (c) is less than 1/10, the dispersing power for forming oil droplets of the monomer in the initial stage of polymerization is insufficient, so that the polymerization cannot proceed stably and exceeds 10/1. Then, the scale adhesion effect is impaired. If (c) is less than 0.005 parts by weight, the polymerization reaction does not proceed stably and abnormal polymerization occurs. If it exceeds 0.2 parts by weight, the particle size of the obtained resin becomes extremely small.

The monomer used in producing the vinyl chloride resin used in the present invention is a monomer containing vinyl chloride as a main component, and specifically, a vinyl chloride monomer alone or a vinyl chloride monomer. It is a mixture containing 70% by weight or more of a vinyl chloride monomer composed of a monomer copolymerizable with a vinyl monomer and a vinyl chloride monomer.

Examples of the monomer copolymerizable with the vinyl chloride monomer include vinyl esters such as vinyl acetate and vinyl propionate, α-olefins such as ethylene, propylene and isobutyl vinyl ether, 1-chloropropylene, Chlorinated olefins such as 2-chlorobutylene, (meth) acrylates such as methyl (meth) acrylate, maleic anhydride, acrylonitrile, styrene, vinylidene chloride and the like can be mentioned, and these can be used alone. Two or more kinds can be used in combination.

In producing the vinyl chloride resin, a known technique can be used for the method of charging the raw materials used in the present invention. For example, the most common methods are to first charge water and then charge the monomer, to charge the monomer first to reduce the time required to raise the temperature to the polymerization temperature, and then to charge hot water. In addition, a method of simultaneously charging the monomer and the hot water for the purpose of shortening the heating time can be used.

The heat of the polymerization reaction may be removed by a conventional method such as heat removal by an external or internal jacket, a method by a reflux condenser, and the like.

Further, polymerization initiators, polymerization degree regulators, chain transfer agents, pH regulators, gelling improvers, antistatic agents, emulsifiers, and stabilizers conventionally used in the polymerization or copolymerization of vinyl chloride monomers. Any known technique can be used without any hindrance for the agent, scale inhibitor, etc., and their preparation methods can also be used, and the amounts used can be in accordance with conventionally known methods.

[0024]

EXAMPLES The present invention will be described more specifically with reference to the following Examples and Comparative Examples, which are not intended to limit the present invention. In addition, all the water of this example used ion-exchange water. Measurement of characteristic values of the obtained vinyl chloride resin and processability, thermal stability,
Evaluation of physical properties was performed by the following methods.

(1) Average particle size and particle size distribution According to JIS K-6721, 42, 60, 80, 1
Using a sieve of 00, 120, 145, 200 mesh,
The particles were sieved with a sieve shaker, and the average particle diameter (μm) was determined using a 50% passage diameter. The particle size distribution was measured by measuring the weight of the vinyl chloride resin remaining on each mesh and expressed as a weight percentage. Of these, the amount of resin remaining on the 42 mesh was not included in the percentage and was regarded as coarse particles, and the amount of resin that passed through the 200 mesh was regarded as PASS.

(2) Porosity Using a mercury intrusion porosimeter (Model 5-7118, manufactured by AMINCO), a vinyl chloride resin is applied at an absolute pressure of 31 to 1011 psi (pore diameter of 0.175 to 5.65 μm). Measure the volume of mercury injected, and measure the vinyl chloride resin 10
The amount of injected mercury (cc) per 0 g was calculated.

(3) Processability 100 parts by weight of vinyl chloride resin and 0.5 parts of an organic tin stabilizer
Parts by weight, 0.1 part by weight of a fatty acid ester-based lubricant, and 0.2 parts by weight of a polyethylene-based lubricant, and after sufficiently stirring and mixing,
It was put into an 8-inch roll whose surface temperature was adjusted to 170 ° C, 180 ° C or 190 ° C. Kneading at each temperature for 5 minutes, taking out a roll sheet of about 0.5 mm thickness,
The finished state of the sheet was visually checked, and the workability was evaluated in three steps according to the following evaluation criteria. …: Sufficiently kneaded to obtain a uniform sheet. Δ: Some unevenness was observed in the sheet due to slightly insufficient kneading. ×: Insufficient kneading at all, and the sheet has holes everywhere.

(4) Thermal stability 100 parts by weight of vinyl chloride resin and 0.5 parts of organotin stabilizer
Parts by weight, 0.1 part by weight of a fatty acid ester-based lubricant, and 0.2 parts by weight of a polyethylene-based lubricant, and after sufficiently stirring and mixing,
60 g of this mixture (composition using a vinyl chloride resin having an average degree of polymerization of 1300 type) or 62 g (composition using a vinyl chloride resin having an average degree of polymerization of 1000 type) was used as a laboplast mill tester (Toyo Seiki Co., Ltd.) )), The rotor rotation speed is 50 rpm, and the chamber temperature is 18
Under the condition of 0 ° C., the time from the introduction of the vinyl chloride resin composition to the rise of the torque was measured. The longer this time, the higher the thermal stability.

(5) Scale Adhesion A known scale inhibitor was applied to the inner wall of a 2,000-L stainless steel polymerization vessel equipped with a stirrer in the initial batch, and the polymerization performed in this study was continuously performed for 10 batches. After that, the scale state adhered to the inner wall was visually checked, and the scale adhered state was evaluated in three steps according to the following evaluation criteria. …: Scale hardly adhered to the inner wall of the polymerization vessel. Δ: A small amount of scale adhered to the inner wall of the polymerization vessel, and the wall was not visible. X: A large amount of scale adhered to the inner wall of the polymerization vessel.

Examples 1 and 3 A well-known anti-scale agent was applied to a 2000 L stainless steel polymerization vessel equipped with a stirrer, and then PVA having a saponification degree of 74% and an average polymerization degree of 2000 (hereinafter referred to as PVA). ,
7.33k of a 3% by weight aqueous solution of "PVA (a)")
g, PVA having a saponification degree of 56% and an average polymerization degree of 300
(Hereinafter referred to as “PVA (b)”) 0.165 kg,
1.1 kg of a chitosan solution having a concentration of 0.5% by weight dissolved in 0.5% acetic acid and 0.393 kg of an isoparaffin solution having a concentration of 70% of di-2-ethylhexylperoxydicarbonate were charged. PVA (a), PV
A (b), the amount of the chitosan solution dissolved at a concentration of 0.5% by weight with respect to 0.5% acetic acid, and the charged amount of di-2-ethylhexyl peroxydicarbonate were 100 parts by weight of the vinyl chloride monomer. 0.04, 0.03, respectively
0.01 and 0.05 parts by weight.

After the polymerization vessel was sealed, the inside was degassed with a vacuum pump, and then 550 kg of vinyl chloride monomer and 725 kg of hot water adjusted to 60 ° C. after degassing were sequentially charged. At this time, the stirrer was operated simultaneously with the start of the charging of the vinyl chloride monomer. Next, the internal temperature of the polymerization reactor was raised to 51.5 ° C. in Example 1 and 57 ° C. in Example 3 by using an external jacket, and maintained at this temperature.
When the pressure decreased by 7 kPa, the polymerization reaction was stopped, unreacted monomers were recovered, and the polymerization reaction was terminated. The obtained slurry was dehydrated and dried to obtain two types of vinyl chloride resins having an average degree of polymerization of 1300 in Example 1 and an average degree of polymerization of 1000 in Example 3, and having various average particle diameter, particle size distribution and porosity. It was used for measurement of characteristic values.

Further, 200 g of the obtained vinyl chloride resin
1 g of methyltin mercapto stabilizer, 0.2 g of pentaerythritol-based lubricant and 0.4 g of polyethylene-based lubricant
Was added and sufficiently stirred and mixed to obtain a composition, which was used for evaluation of processability and thermal stability.

Examples 2 and 4 PVA (a), PVA (b), 0.5% by weight chitosan
The charged amounts of the 0.5% acetic acid aqueous solution and di-2-ethylhexyl peroxydicarbonate were 0.02 and 0.02, respectively, based on 100 parts by weight of the vinyl chloride monomer.
1, 0.1 and 0.05 parts by weight. Except for this, the same procedures as in Examples 1 and 3 were carried out. In Example 2, two types of vinyl chloride resins and compositions having an average degree of polymerization of 1300 were obtained, and in Example 4, an average degree of polymerization of 1,000 was obtained. It was used for evaluation of processability evaluation and thermal stability evaluation.

COMPARATIVE EXAMPLE 1 A 3% by weight aqueous solution of PVA (a) as a dispersant, 9.99 k
g (0.05 parts by weight per 100 parts by weight of vinyl chloride monomer)
2.2 kg of a 0.5% by weight aqueous solution of polyethylene oxide having a molecular weight of 4.5 million (hereinafter referred to as “PEO”) (0.002 parts by weight per 100 parts by weight of vinyl chloride monomer) Using only the seeds, a vinyl chloride resin and a composition having an average degree of polymerization of 1300 type were obtained in the same manner as in Example 1, and subjected to measurement of various characteristic values, evaluation of workability and evaluation of thermal stability.

Comparative Example 2 As a dispersant, PVA (a) was used as a PVA (a) having a saponification degree of 80% and an average degree of polymerization of 2000.
g (0.05 parts by weight per 100 parts by weight of vinyl chloride monomer)
4 parts by weight), and a 3% by weight aqueous solution of PVA having a degree of saponification of 88% and an average degree of polymerization of 2,300 as PVA (b) 2.2.
kg (0.0 to 100 parts by weight of vinyl chloride monomer)
12 parts by weight) and a 0.5% by weight aqueous solution of PEO.
5 kg (0.1 parts by weight per 100 parts by weight of vinyl chloride monomer)
005 parts by weight), except that a vinyl chloride resin and a composition having an average degree of polymerization of 1000 were obtained in the same manner as in Example 3 except that only three kinds were used, and measurement of various characteristic values, evaluation of processability and evaluation of thermal stability For evaluation.

Comparative Example 3 PVA (a) had a saponification degree of 88% and an average polymerization degree of 20
Using PVA which is 00 and PE instead of chitosan solution
Except for using O, the average degree of polymerization was 13 in the same manner as in Example 1.
A 00 type vinyl chloride resin and composition were obtained, and were subjected to measurement of various characteristic values, evaluation of processability and evaluation of thermal stability.

Table 1 summarizes the evaluation results.

[0038]

[Table 1]

[0039]

According to the present invention, it is possible to carry out polymerization of a vinyl chloride resin having little scale adhesion during polymerization and excellent in processability and thermal stability and without deterioration in physical properties. Therefore, the industrial value of the present invention is extremely large.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J011 AA01 DA03 EA03 EA06 JA07 JA08 JA10 JB24 4J100 AA02Q AA03Q AB02Q AC02Q AC03P AC04Q AE06Q AG02Q AG04Q AK32Q AL03Q AM02Q CA01 CA04 FA21 JA44 JA58

Claims (3)

[Claims] When a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a monomer copolymerizable with the vinyl chloride monomer is subjected to suspension polymerization in an aqueous medium, a vinyl chloride monomer Body, or a mixture of a monomer copolymerizable with a vinyl chloride monomer and a vinyl chloride monomer, as a suspending dispersant,
(A) The degree of saponification is 70 to 85%, the average degree of polymerization is 1500 to
(B) partially saponified polyvinyl acetate having a saponification degree of 33 to 70% and an average degree of polymerization of 200 to 1000; and (c) an aqueous solution of chitosan in an organic acid. Manufacturing method of vinyl chloride resin. 2. A suspension and dispersant for 100 parts by weight of a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a monomer copolymerizable with the vinyl chloride monomer, wherein
From 0.02 to 0.08 parts by weight, and (b) from 0.01 to
0.05 parts by weight, and 0.005 to 0.5 parts by weight of (c).
2. The method for producing a vinyl chloride resin according to claim 1, wherein 2 parts by weight are used. 3. A suspension and dispersant for 100 parts by weight of a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a monomer copolymerizable with the vinyl chloride monomer, , (B) and (c) by (a) / (b) = 1 /
The total number of copies of (a) + (b) is 0.0 at a ratio of 1 to 5/1.
2 to 0.08 parts by weight, (a + b) / (c) = 1/10
2. The method for producing a vinyl chloride resin according to claim 1, wherein 0.005 to 0.2 parts by weight of (c) is used in a ratio of 10/1.