JPH0892305A - Method for producing vinyl chloride resin - Google Patents

Abstract

PURPOSE: To produce a readily processable resin having a low gelation temperature and a large surface area of partially skinless grains by polymerizing vinyl chloride monomer using a specific anionic surfactant and a water-soluble polymer as a suspending agent. CONSTITUTION: This method for producing a vinyl chloride-based resin comprises dispersing vinyl chloride monomer or a mixture thereof with other monomers copolymerizable therewith in an aqueous medium using a water-soluble polymer as a suspending agent, using a polymerization initiator capable of dissolving the vinyl chloride monomer and (co)polymerizing the monomers in the coexistence of an anionic surfactant, insoluble in water and soluble in the vinyl chloride monomer. Methyl cellulose and sodium or potassium polyacrylate are used as the suspending agent. A low-degree sulfated oil, a petroleum sulfonate having an extremely large hydrophobic group (a sodium alkylbenzenesulfonate) and a water-insoluble metallic salt (a barium or a calcium alkylbenzenesulfonate) are used as the anionic surfactant. Lauroyl peroxide, etc., are used as the polymeriz at ion initiator.

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. In particular, the present invention relates to a method for producing a vinyl chloride resin, which has a characteristic that the obtained vinyl chloride resin is easy to process.

[0002]

2. Description of the Related Art Vinyl chloride resins can be produced by various methods. For example, it can be prepared by a suspension polymerization method, an emulsion polymerization method, a bulk polymerization method, or the like. However, the suspension polymerization method is superior in terms of efficiently producing a high-quality vinyl chloride resin containing few impurities. Therefore, the suspension polymerization method is widely used today except in special cases.

In the suspension polymerization method, a vinyl chloride monomer is dispersed in an aqueous medium with the aid of a suspending agent, and a vinyl chloride monomer is polymerized using a polymerization initiator which dissolves in the monomer. It is a method to let. This polymerization method is not limited to the case where only vinyl chloride is used as a monomer, but can be applied to the case where a mixture of vinyl chloride and another monomer copolymerizable with vinyl chloride is used for copolymerization. Therefore, a resin generally called a vinyl chloride resin can be produced by a suspension polymerization method.

In the above suspension polymerization, various suspending agents have been used. The suspending agent is roughly classified into high molecular weight substances and low molecular weight substances. As a polymer,
In addition to synthetic polymers such as polyvinyl alcohol, especially partially saponified polyvinyl alcohol, water-soluble cellulose derivatives such as methyl cellulose and carboxymethyl cellulose have been used. Surfactants such as sorbitan monolaurate ester, glycerin monostearate ester, sodium lauryl sulfate and sodium dodecylbenzenesulfonate were used as the low molecular weight compound. In all cases, the suspensions used so far are water-soluble.

A vinyl chloride resin (hereinafter, abbreviated as PVC) is often used as a molded product by blending various materials and kneading under heating to form various shapes. . However, PVC generally has poor thermal stability,
It has the drawback that it decomposes and colors when heated. Therefore, it is required that PVC can be easily heated to form a molded product without being decomposed, and whether the resin is acceptable or not is determined depending on whether or not this requirement is satisfied.

[0006] For example, PVC is often mixed with a plasticizer, a stabilizer and the like to form a molded article. However, when the mixture is heated and gelled, the gelling temperature is low. It is used as a guideline for determining the ease of use. That is, if the gelling temperature is low, a uniform composition can be obtained without decomposing PVC within a short period of time by kneading the mixture under heating, which facilitates the processing.
Therefore, the temperature at which such a uniform composition is formed is called the gelation temperature, and the lower the gelation temperature, the better the processability.

However, the PVC produced up to now by the suspension polymerization method has generally not been easy to process. For example, when the gelation temperature is taken, the PVC used so far has a high gelation temperature. Further, when the blackening time of the PVC composition, that is, the time until the composition decomposes and blackens when the composition is heated, the blackening time was short. Therefore, it has been required to provide a PVC that is easier to process.

[0008]

DISCLOSURE OF THE INVENTION The present invention is intended to provide a method for producing a PVC capable of obtaining a PVC that can be easily processed.

[0009]

The present inventor has attempted to manufacture PVC by various methods and process it in order to solve the above problems. As a result, it has been found that there are various methods for producing PVC, but in order to industrially produce PVC that is easy to process, the Yatori suspension polymerization method is preferable. Further, in the conventional suspension polymerization method, a water-soluble polymer or a low-molecular weight substance has been used as a suspending agent. It was found that PVC which is easy to process can be obtained by carrying out the polymerization using an anionic surfactant which is soluble in a vinyl chloride monomer as a suspending agent but is not soluble in.

The surfactants that have hitherto been used as suspending agents in the suspension polymerization of vinyl chloride monomers were all water-soluble, as mentioned above. However, this invention
The method of the present invention is different from the conventional method in this respect because a surfactant having a property of being dissolved in a vinyl chloride monomer without being dissolved in water is used. Further, the surfactant which is not dissolved in water but is soluble in the vinyl chloride monomer needs to be anionically active.
The inventors of the present invention have found that when an anionic surfactant which is insoluble in water and soluble in vinyl chloride is used as a suspending agent in the suspension polymerization of vinyl chloride, the obtained PVC becomes easy to process. Has found.

Further, the polymerization of PVC using an anionic surfactant which is insoluble in water and soluble in vinyl chloride is not limited to homopolymerization of vinyl chloride, but also in the case of copolymerizing vinyl chloride with other monomers. It has been found that a similar effect can be obtained.
The present invention has been completed based on such knowledge.

According to the present invention, a water-soluble polymer is used as a suspending agent, and a vinyl chloride monomer or a mixture with another monomer copolymerizable with the vinyl chloride monomer is dispersed in an aqueous medium to form a chloride. In a method for producing a vinyl chloride resin by polymerizing or copolymerizing the above monomers using a polymerization initiator that dissolves in a vinyl monomer, an anionic interface that dissolves in a vinyl chloride monomer without being dissolved in water The gist of the present invention is a method for producing a vinyl chloride resin, which comprises adding an activator to carry out polymerization or copolymerization.

The present invention follows the conventional suspension polymerization method. However, it is necessary to select and use a water-soluble polymer from those that have been used as suspending agents, and those that have never been used in suspension polymerization of PVC as suspending agents. It is characterized by using. The suspending agent which has not been used until now is the above-mentioned anionic surfactant which is not dissolved in water but is dissolved in the vinyl chloride monomer.

In the present invention, at least two suspending agents are used. One of them is a conventionally used water-soluble polymer. Therefore, first of all, this water-soluble polymer will be classified into a cellulose derivative and a synthetic polymer, and it is sufficient to use at least one of them. As the cellulose derivative, in addition to the above-mentioned methyl cellulose and carboxymethyl cellulose,
Ethyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, hydroxyethyl cellulose and the like can be used. As the synthetic polymer, in addition to the above-mentioned polyvinyl alcohol and partially saponified polyvinyl alcohol, a special saponification polyvinyl alcohol having a degree of saponification of 60 to 80 containing 0.02 to 5 mol% of a sulfuric acid ester or a phosphoric acid ester. Mol% of modified polyvinyl alcohol, 0.02 to 10 mol% of anionic hydrophilic group such as carboxylic acid group, sulfonic acid group and 0.
Modified polyvinyl alcohol having a saponification degree of 60 to 90 mol% containing 01 to 5 mol% of a hydrophobic group, vinyl acetate / maleic acid copolymer, polyvinylpyrrolidone, polyacrylate, high molecular weight polyethylene glycol, polypropylene glycol, etc. Can be used. It is suitable to use sodium polyacrylate or potassium polyacrylate as the polyacrylate.

The present invention is most characterized in that an anionic surfactant which is insoluble in water but is soluble in a vinyl chloride monomer is used as a suspending agent. Examples of such a surfactant include a low-sulfated oil having a reduced number of hydrophilic groups, a petroleum sulfonate having an extremely large hydrophobic group, an amine salt having a counterion selected to be oil-soluble, and a water-insoluble agent. A metal salt or the like can be used. The details of these are as follows.

The low-sulfated oil having a reduced number of hydrophilic groups is
For example, among the sulfated oils called funnel oil, the amount of bound sulfuric acid / total fat in the range of about 5% to at most 10% corresponds to this. The petroleum sulfonate having an extremely large hydrophobic group is, for example, a straight chain sodium alkylbenzene sulfonate having 12 or more, preferably 20 or more carbon atoms. The water-insoluble metal salt is, for example, a barium or calcium salt of alkylbenzene sulfonic acid.

[0017]

[Chemical 1]

It is Of the anionically active surfactants sold by Moresco under the name Thulhol, the oil-soluble ones can be used in the process according to the invention.

The above water-soluble polymer is preferably used in an amount of 0.005 to 0.2% by weight, more preferably 0.01 to 0.1% by weight based on the vinyl chloride monomer. It is suitable. Further, the above-mentioned water-insoluble and vinyl chloride-soluble anionic surfactant has a ratio of 1 to vinyl chloride monomer.
It is suitable to use ~ 200ppm, and among them 10 ~
It is more preferable to use it in the range of 100 ppm. The reason is that when the amount of the above-mentioned anion activator is within the range of 1 to 200 ppm, the P obtained is as described below.
Although the specific surface area of the VC particles is remarkably increased, good results can be obtained. However, if the amount of the anionic activator is less than 1 ppm, the effect of addition does not appear. Conversely, if it exceeds 200 ppm, the obtained PVC particles are large. This is because a good result cannot be obtained because the polymerization reaction does not proceed smoothly or the polymerization reaction does not proceed smoothly.

The present invention uses an aqueous medium as a medium for carrying out suspension polymerization. Deionized water is preferred as the aqueous medium. The amount ratio of vinyl chloride and aqueous medium is the same as the range conventionally used, but the range is about 1
A range of 1 to 3 is suitable.

In the present invention, a polymerization initiator is used for carrying out suspension polymerization, but the polymerization initiator needs to be soluble in the vinyl chloride monomer. The polymerization initiator has hitherto been used for suspension polymerization of vinyl chloride. Examples are organic peroxides such as lauroyl peroxide, α-cumylperoxy neodecanoate, t-butylperoxy neodecanoate, and 2,2′-azobisisobutyronitrile. Is an azo compound such as.

The method of the present invention can be applied not only to the case where only vinyl chloride is used as a monomer, but also to the case where a mixture of vinyl chloride and another monomer is used. Other monomers include ethylene, propylene, vinyl acetate,
Alkyl vinyl ethers, acrylic acid and methacrylic acid and their esters can be used.

The process according to the invention is carried out in the same manner as conventional suspension polymerization, except that the special ones mentioned above are used as suspending agents. That is, an autoclave is used as a container, first an aqueous medium such as deionized water is put therein, and then a suspending agent is added thereto and dissolved by stirring. After adding a vinyl monomer and dispersing the monomer in an aqueous medium to make a suspension, a polymerization initiator is added to this. The autoclave is then heated and the contents are maintained at elevated temperature for several hours to allow the monomers to polymerize. When the polymerization proceeds and the pressure of the monomer in the autoclave decreases, the autoclave is cooled to lower the temperature of the content, unreacted monomer is recovered, and the content is taken out. It is then dehydrated and dried to obtain PVC.

[0024]

The method of the present invention is different from the conventional method in that a special suspending agent is used, but in other respects, it can be carried out in the same manner as the conventional method. Moreover, the special suspending agent used therein is an anionic surfactant which is insoluble in water and soluble in the vinyl chloride monomer, and which is commercially available. Therefore, the invention is easy to implement. Since the above-mentioned anionic surfactant is used in the present invention, the effect of stabilizing the domain particles, which are the constituent material of the PVC particles, is remarkable, and therefore the inside of the primary particles of the PVC particles is made porous, and as a result, the PVC particles are made porous. It shows the effect of increasing the specific surface area of the particles. The PVC thus obtained has a totally unexpected and remarkable effect in that it is easy to process.

The PVC obtained by the method of the present invention is
The ease of processing is directly indicated by the low gelling temperature during processing, but also the resulting PVC
The average particle size, bulk specific gravity, and porosity are within the range that has been conventionally considered to be easy to process, and the specific surface area of particles is larger than conventional particles, and When observed under a microscope, it is understood that the resin obtained by the present invention is partially skinless.

The supplementary description of the skinless point is as follows. Generally, the PVC particles obtained by suspension polymerization have a diameter of 50 to 150 μm and are called grain particles. Grain particles have a smaller particle size and are made by aggregating primary particles of 0.5 to 2.0 μm.
Diameter called domain particle is 0.05 ~ 0.15μm
It is composed of a set of fine particles. PVC particles that have been produced by conventional suspension polymerization do not expose the surface of the primary particles because the surface of the grain particles is covered by the film (skin) generated by the suspending agent, Therefore, the surface area appeared as a small value. However, most of the PVC particles (grain particles) produced by the method of the present invention are not covered by the skin, and the surfaces of the primary particles are exposed, which results in a large surface area. At the same time, the effect of heat interference by the skin disappears, so gelation by heating becomes easier,
Therefore, the gelling temperature is lowered and the processing becomes easy.

[0027]

[Examples] Hereinafter, the reason why the method of the present invention is excellent will be specifically described by giving Examples and Comparative Examples. In the examples and the comparative examples, “parts” means “parts by weight”. In addition, the average particle diameter, bulk specific gravity, porosity, specific surface area and gelling temperature of the obtained PVC are measured there. The measuring method is as follows.

The average particle size was measured with a Microtrac MKII particle size distribution meter (model 7997-10 type) manufactured by Nikkiso Co., Ltd.

Bulk Specific Gravity The bulk specific gravity was measured by the method specified in JIS K6721.

Porosity The volume of the pores contained in a unit weight of PVC particles is called the pore volume (milliliter / g), and the ratio of the pore volume to the total volume of PVC is expressed as a percentage and called the porosity. .
This porosity is measured by the mercury press-in type porosimeter (Carloe
Rba Porosimeter 2000) with a gauge pressure of 2
Applying pressure up to 000 kg / cm ² , pore radius 0.0
Mercury is pressed up to 1 μm, and the volume of mercury (c
c) is measured, the weight of PVC is measured separately, the volume (cc) of PVC is calculated with the true specific gravity of PVC being 1.4, and the porosity is calculated by the following formula. Volume of PVC = PVC weight (g) / specific gravity (1.4) Porosity = amount of injected mercury (cc) / {PVC volume (cc) +
Amount of mercury injected (cc)} x 100%

Specific Surface Area The specific surface area is represented by the sum of the surface areas of all pores contained in a unit weight of PVC particles. The specific surface area inside the PVC particles is
From the volume of each pore measured by mercury porosimetry porosimeter, the surface area of each pore is determined assuming that the pores are cylindrical,
This integrated value was defined as the specific surface area within the grain particles.

Gelation Temperature First, the following formulation was made. PVC 100 parts Dioctyltin mercapto 2 parts (Nippon Kagaku Co., TUS-8831) Calcium stearate 0.5 parts (Sakai Kagaku Co., SC-100) Ester wax 0.5 parts (Hoechst Co., wax-op) 55 g of the above compound was added to Halast Plastomill R-
The mixture was put in 90 and kneaded while raising the temperature from 150 ° C. to 5 ° C. per minute at a rotation speed of 40 rpm, and the temperature at which the kneading torque peaks was taken as the gelling temperature.

[0033]

Example 1 In this example, a partially saponified polyvinyl alcohol and hydroxypropylmethyl cellulose were used as a suspending agent composed of a water-soluble polymer, and an anionic surfactant which was dissolved in a vinyl chloride monomer without being dissolved in water. Sodium eicosylbenzene sulfonate was used as the suspending agent. The details of the implementation are as follows.

An autoclave having an internal volume of 216 liters was charged with 143 parts of deionized water, and as a suspending agent, a partially saponified polyvinyl alcohol having a saponification degree of 72 mol% 0.05
Parts and hydroxypropyl methylcellulose 0.03 parts,
After adding 0.005 parts of sodium eicosylbenzenesulfonate and removing the oxygen in the autoclave under reduced pressure, 100 parts of vinyl chloride monomer and 0.017 part of α-cumylperoxy neodecanoate as a polymerization initiator were added. , T-butyl peroxy neodecanoate 0.06 part was added.

The contents are heated to 58 ° C. by heating the autoclave.
Polymerization is carried out while maintaining the temperature of
When the amount reached g / cm ² , unreacted vinyl chloride monomer was recovered, the contents were taken out, dehydrated to obtain PVC, and dried. The PVC thus obtained has a polymerization yield of 85.
%Met. The average degree of polymerization of this PVC was 1000.

When the obtained PVC was measured,
The average particle size is 180 μm, the bulk specific gravity is 0.580 g / cc,
The porosity is 21%, the specific surface area is 4.80 m ² / g, and the average particle size, bulk specific gravity, and porosity are superior to those of conventional PV.
Although it was equivalent to C, the value of the specific surface area was remarkably large. The surface of the PVC particles was as shown in FIG. 1 of the micrograph and was in a partially skinless state.
This PVC had a gelation temperature of 160 ° C. and was easy to process.

[0037]

Example 2 In this example, calcium dodecylbenzene sulfonate was used as an anionic surfactant insoluble in water and soluble in vinyl chloride monomer. In particular,
In Example 1, the amount of partially saponified polyvinyl alcohol is 0.06 part, the amount of hydroxymethyl cellulose is 0.02 part, and 0.01 part of calcium dodecylbenzenesulfonate is used instead of sodium eicosylbenzenesulfonate. Except for this, the same procedure as in Example 1 was performed.

When the obtained PVC was measured,
The average particle size is 165 μm, the bulk specific gravity is 0.565 g / cc,
The porosity was 22% and the specific surface area was 5.10 m ² / g, and the value of the specific surface area was remarkably large. Also, this P
The surface of the VC particles was as shown in FIG. 2 of the micrograph and was in a partially skinless state. This PVC had a gelation temperature of 158 ° C. and was easy to process.

[0039]

Example 3 In Example 1, the amount of partially saponified polyvinyl alcohol was increased to 0.08 parts, and the amount of hydroxymethyl cellulose was decreased to 0.01 parts. Sodium eicosylbenzenesulfonate was replaced with dodecylbenzenesulfone. The procedure of Example 1 was repeated except that 0.002 parts of barium acid was used.

When the obtained PVC was measured,
The average particle size is 160 μm, the bulk specific gravity is 0.550 g / cc,
The porosity was 22% and the specific surface area was 4.34 m ² / g, and the value of the specific surface area was remarkably large. Also, this P
The surface of the VC particles was as shown in FIG. 3 of the micrograph and was in a partially skinless state. This PVC had a gelation temperature of 162 ° C. and was easy to process.

[0041]

Example 4 In Example 1, the amount of partially saponified polyvinyl alcohol was reduced to 0.04 parts, the amount of hydroxymethyl cellulose was increased to 0.04 parts, and the amount of sodium eicosylbenzenesulfonate was reduced to 0. .001
Example 1 was carried out in exactly the same manner as in Example 1 except that the parts were used.

When the obtained PVC was measured,
The average particle size is 170 μm, the bulk specific gravity is 0.570 g / cc,
The porosity was 20%, the specific surface area was 3.75 m ² / g, and the specific surface area was large. The surface of the PVC particles was as shown in Fig. 4 of the micrograph and was in a partially skinless state. This PVC has a gelation temperature of 1
It was 64 ° C. and was easy to process.

[0043]

Example 5 In addition to 0.05 part of partially saponified polyvinyl alcohol having a saponification degree of 72% used in Example 1, 0.03 part of a saponification degree of 50% is used. Except for the above, the same procedure as in Example 1 was carried out.

When the obtained PVC was measured,
The average particle size is 155 μm, the bulk specific gravity is 0.505 g / cc,
The porosity was 30% and the specific surface area was 4.50 m ² / g, and the specific surface area was remarkably large. Also, this PVC
The surface of the particles was as shown in Fig. 5 of the micrograph and was in a partially skinless state. This PVC had a gelation temperature of 161 ° C. and was easy to process.

[0045]

Example 6 The procedure of Example 1 was repeated, except that the amount of partially saponified polyvinyl alcohol was increased to 0.07 part and that hydroxymethyl cellulose was not used.

The PVC obtained has an average particle size of 185 μm.
m, the bulk specific gravity was 0.570 g / cc, the porosity was 21%, and the specific surface area was 4.50 m ² / g, and the specific surface area was remarkably large. The surface of the PVC particles was as shown in FIG. 6 of the micrograph and was in a partially skinless state. This PVC had a gelation temperature of 162 ° C. and was easy to process.

[0047]

Example 7 The procedure of Example 1 was repeated except that the partially saponified polyvinyl alcohol was not used and the amount of hydroxymethyl cellulose used was increased to 0.07 part.

The obtained PVC has an average particle size of 180 μm.
m, the bulk specific gravity was 0.585 g / cc, the porosity was 22%, and the specific surface area was 4.38 m ² / g, and the specific surface area was remarkably large. The surface of the PVC particles was as shown in FIG. 7 of the micrograph and was in a partially skinless state. This PVC had a gelation temperature of 164 ° C. and was easy to process.

[0049]

Comparative Example 1 Example 1 is the same as Example 1 except that sodium eicosylbenzene sulfonate is not used.
It carried out exactly like the above.

The PVC obtained has an average particle size of 175 μm.
m, the bulk specific gravity was 0.590 g / cc, the porosity was 22%, and the specific surface area was 1.50 m ² / g, showing a specific surface area smaller than that of the example. Also, this PVC
The surface of the particles is as shown in the micrograph of FIG. 8, and most of the particles were covered with the skin, and the primary particles were hardly exposed. This PVC has a gelation temperature of 174 ° C.
However, the processing was difficult as compared with the examples.

[0051]

Comparative Example 2 The procedure of Example 1 was repeated, except that 0.005 parts of sodium dodecylbenzene sulfonate was used instead of sodium eicosyl benzene sulfonate.

The above-mentioned sodium dodecylbenzene sulfonate is soluble in water. The above aqueous dispersion could not be suspension polymerized.

[0053]

Comparative Example 3 In Example 1, 0.05 parts of the partially saponified polyvinyl alcohol having a saponification degree of 72% used in Example 1 was further added, and 0.03 part of a saponification degree of 50% was further added. The same procedure as in Example 1 was carried out except that sodium eicosylbenzenesulfonate was not used.

The obtained PVC has an average particle size of 150 μm.
m, the bulk specific gravity was 0.510 g / cc, the porosity was 28%, and the specific surface area was 1.67 m ² / g, and the value of the specific surface area was smaller than that of the example. The PVC particles had a surface state as shown in the micrograph of FIG. 9, and most of them were covered with a skin, and the primary particles were hardly exposed. This PVC has a gelation temperature of 172 ° C.
However, the processing was difficult as compared with the examples.

[Brief description of drawings]

1 is a micrograph of PVC particles obtained in Example 1. FIG.

FIG. 2 is a micrograph of PVC particles obtained in Example 2.

FIG. 3 is a micrograph of PVC particles obtained in Example 3.

FIG. 4 is a micrograph of the PVC particles obtained in Example 4.

5 is a micrograph of PVC particles obtained in Example 5. FIG.

FIG. 6 is a micrograph of the PVC particles obtained in Example 6.

FIG. 7 is a micrograph of PVC particles obtained in Example 7.

8 is a micrograph of PVC particles obtained in Comparative Example 1. FIG.

9 is a micrograph of PVC particles obtained in Comparative Example 3. FIG.

Claims (1)

[Claims] 1. A water-soluble polymer is used as a suspension agent,
A vinyl chloride monomer or a mixture with another monomer copolymerizable therewith is dispersed in an aqueous medium, and the above-mentioned monomer is polymerized by using a polymerization initiator which is dissolved in the vinyl chloride monomer. Alternatively, in the method of producing a vinyl chloride resin by copolymerization, characterized by adding an anionic surfactant that is soluble in a vinyl chloride monomer without being dissolved in water to perform polymerization or copolymerization, Method for producing vinyl resin.