JPS61278512A - Production of vinyl chloride copolymer - Google Patents

Abstract

PURPOSE:To obtain the titled copolymer which is homogeneous and highly random, by directly feeding vinyl chloride, an alpha,beta-ethylenically unsaturated carboxylic acid glycol monoester and a saturated carboxylic acid vinyl ester into a polymerization system at a specified flow rate. CONSTITUTION:A polymerization system containing a solvent and an oil-soluble polymerization initiator (e.g., dibenzoyl peroxide) is heated to a specified temperature. While a monomer mixture comprising 50-80wt% vinyl chloride monomer, 2-30wt% alpha,beta-ethylenically unsaturated carboxylic acid glycol monoester (e.g., propylene glycol monoester) and 5-40wt% 1-6C saturated carboxylic acid vinyl ester monomer (e.g., vinyl acetate) is being directly fed at a flow rate >=5cm/sec, it is copolymerized to obtain a homogeneous, random vinyl chloride copolymer of an average degree of polymerization of 100-500.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a vinyl chloride copolymer which can be cured with isocyanate or the like to form an improved coating film as a coating material.

[Conventional technology]

In the paint industry it is important to provide crosslinkable vinyl chloride copolymers. As crosslinkable copolymers, copolymers containing free hydroxyl groups are particularly advantageous in that they can be crosslinked in various ways. In the past, these types of copolymers were mostly made by partially saponifying vinyl chloride/vinyl acetate copolymers to generate free hydroxyl groups in the polymer. However, this type of copolymer has drawbacks such as color deterioration due to the saponification process and increased cost.

Another known method for producing vinyl chloride copolymers containing hydroxyl groups is to copolymerize vinyl chloride with acrylic acid hydroxyalkyl esters. However, such copolymers often have the disadvantage that most of them become reticulated during polymerization and cannot be used as raw materials for coatings. Regarding research to improve this drawback, there are several documents, such as the following: Japanese Patent Publication No. 1,757/1982. Public notice 1987-10, 87
3 and the same publication No. 52-24558 and Patent Publication No. 1,757 No. 51 disclose a method in which vinyl chloride and 2-hydroxypropyl acrylate are continuously polymerized in an emulsified state in water.

However, acrylic acid hydroxyalkyl ester monomers other than 2-hydroxypropyl acrylate, e.g.
~ With hydroxyethyl acrylate, the copolymer is insoluble in common solvents, suggesting that strong crosslinking occurs.

Patent Publications No. 10, 873, 1982 and 24, No. 1983.
No. 558 discloses a method in which vinyl chloride, vinyl acetate, and hydroxyalkyl acrylate are continuously polymerized in a solution. However, in order to homogeneously copolymerize acrylic acid hydroxyacrylic ester, which has a significantly different polymerizability compared to vinyl chloride, simply feeding the monomer continuously will cause heterogeneous polymerization and often result in turbidity. occurs.

A vinyl chloride copolymer using 2-hydroxyethyl acrylate has a highly reactive primary hydroxyl group, so it forms a strong bond with isocyanate and the like, forming a tough coating film. However, patent publication 1975-1, 75
As stated in 7, 2-hydroxyethyl acrylate tends to form trapping insoluble substances during copolymerization, making it difficult to obtain a resin that is good as a raw material for coatings.

[Problem that the invention seeks to solve]

The object of the present invention is to form a network at the stage of polymerization in the conventional technology,
2- Only materials that cannot be used as paint raw materials can be obtained.
The object of the present invention is to provide a method for producing a resin that has similar excellent solubility in copolymerization of hydroxyethyl acrylate with vinyl chloride and can be cured with isocyanates and the like to form improved coating films. .

[Means for solving problems]

That is, the present invention provides continuous K
The production method is characterized by supplying at a flow rate of 5 cm/sea or more and directly inserting into the internal solution of the polymerization system, and the vinyl chloride monomer is 50 to 80% by weight! jk%, α, β
Average degree of polymerization (J The present invention relates to a method for producing a homogeneous random copolymer having a particle diameter of 100 to Saa (measured according to S.K. 6721).

The details will be explained below.

[Effect]

In the present invention, conventional radical polymerization techniques such as suspension, emulsion, or solution polymerization can be used, but solution polymerization is preferred. Solution polymerization is carried out in a solvent for the monomers used in the production and the resulting copolymer. Such solvents that can be used in the present invention include esters such as ethyl acetate and butyl acetate; ketones such as methyl ethyl ketone and methyl isobutyl ketone, and toluene.

Aromatic hydrocarbons such as xylene may be used alone or in mixtures.

In the present invention, at least 50% or more of the monomers are continuously fed into the polymerization system. The monomers that are continuously supplied have a composition that can maintain a constant monomer composition distribution within the polymerization system during polymerization, and each monomer is supplied according to its respective polymerization rate. This is necessary to make the composition distribution of the copolymer uniform, but what is more important is the method of supplying the monomer into the polymerization system. That is, the monomer composition is supplied through a tube led into the internal solution of the polymerization system at a flow rate of 5 an/sec or more. This makes it possible to quickly diffuse the monomer into the polymerization system, and to carry out the polymerization while always maintaining a uniform monomer composition distribution within the polymerization system.

In particular, when the viscosity of the solution in the polymerization system increases, there will be poor mixing that cannot be compensated for by the stirring rotation speed or the shape of the blades. appears, producing a heterogeneous polymer. The flow rate is determined by the diameter of the inlet tube that supplies the monomer, but as mentioned earlier, the continuous supply rate (flow rate) of the monomer is determined by the polymerization rate of each monomer. Therefore, the diameter of the introduction tube varies depending on the polymerization conditions.For example, 1
In order to obtain a flow rate of 5 car/sea or more when copolymerizing monomers having the composition of the present invention using a polymerization kettle of 100 m or more, the diameter of the tube should be about 15 m or less. The method of the present invention is particularly effective for 2-hydroxyethyl acrylate, which cannot be obtained by the conventional techniques due to network formation during polymerization, and the obtained vinyl chloride copolymer has homogeneous randomness. It has high solubility in inexpensive paint solvents such as aromatic hydrocarbons such as toluene and xylene, or aliphatic alcohols such as ethanol and methanol.

The polymerization of the present invention is started at a predetermined temperature by charging a monomer, a solvent, and a polymerization initiator into a polymerization container. The combination of temperature, monomer-to-solvent ratio, and type of solvent used controls the molecular weight of the resin. The polymerization initiator is an oil-soluble compound that thermally generates radicals, such as dibenzoyl peroxide,
dilauroyl peroxide, diacetyl peroxide,
Any of azobis(imbutyronitrile), isopropyl peroxydicarbonate, 2-ethylhexyl peroxydicarbonate, etc. can be used. The polymerization initiator can be added all at once at the initial stage, but
Preferably, like the monomer, it is fed continuously to control the polymerization rate.

The vinyl chloride monomer is 50-8 based on the weight of the copolymer.
0% by weight, preferably 60-70% by weight. If the vinyl chloride monomer content is less than 50% by weight, the properties as a vinyl chloride paint, ie, chemical resistance, water resistance, and weather resistance, will be poor. Moreover, if it exceeds 80% by weight, the viscosity of the resin solution will increase and the solubility in inexpensive solvents such as aromatic hydrocarbons will be poor.

The glycol monoester monomer of α-β ethylenically unsaturated carboxylic acid used in the present invention includes acrylic acid, methacrylic acid, and maleic acid.

Unsaturated carboxylic acids such as fumaric acid and itaconic acid, ethylene glycol, furopylene gelicol, phthanediol,
Examples include monoesters with glycols such as bentanediol and bentanediol.

Monomers of particular importance in the present invention are ethylene glycol f or propylene glycol monoesters of acrylic or methacrylic acid. These monomers may be used alone or in combination of 2 to 3 types based on the weight of the copolymer.
It is used in an amount of 0% by weight, preferably 5 to 20% by weight. If it is less than 2% by weight, it is insufficient to obtain a good cured film with incyanate and the like, and the dilutability with aliphatic alcohols such as ethanol is poor. If it exceeds 50% by weight, it is difficult to obtain a transparent resin solution without turbidity, and an increase in the monomer content is also undesirable because it increases the price.

Examples of the vinyl ester monomer of a saturated carboxylic acid containing 1 to 6 carbon atoms used in the present invention include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl persatate, and the like.

These monomers may be used alone or in combination of two or more in an amount of 5 to 40% by weight, preferably 20 to 40% by weight, based on the weight of the copolymer.
Use 55% by weight. If the amount is less than 5% by weight, the solubility in aromatic hydrocarbon solvents will be poor. Also 40% by weight
If it exceeds this, the strength, water resistance, and solvent resistance of the coating film will decrease.

It is used as a cured coating film by co-reacting with formaldehyde resin, epoxy resin, etc.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, (1)
In the prior art, an excellent resin solution is obtained even in the vinyl chloride copolymerization of 2-hydroxyethyl acrylate, which becomes reticulated during polymerization and cannot be used as a paint raw material.

(2) Aromatic hydrocarbons such as inexpensive natoluene, xylene, ethylbenzene, and ethanol.

It is economically advantageous because aliphatic alcohols such as methanol can be used as a solvent.

(3) Since the copolymer resin contains hydroxyl groups, it can be co-reacted with urea-formaldehyde resin, melamine-formaldehyde resin, epoxy resin or incyanate-containing resin to form an excellent cured coating film.

(4) Since the copolymer resin contains hydroxyl groups, it has excellent compatibility with other hydroxy-containing resins.

〔Example〕

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. Note that "part" in the example sentence means "polymerization part."

Example 1 A 1 ton polymerization vessel was charged with 50 parts vinyl chloride, 60 parts vinyl propionate, 4 parts 2-hydroxyethyl acrylate and 180 parts ethyl acetate and the temperature was raised to 65°C. Polymerization was initiated by adding a 5% by weight solution of 2-ethylhexyl peroxydicarbonate catalyst in ethyl acetate to the polymerization vessel at a rate of 5 parts per hour. Next, a mixture of 130 parts of vinyl chloride, 30 parts of vinyl propionate, and 26 parts of 2-hydroxyethyl acrylate was added to a polymerization vessel to a diameter [14! was continuously supplied into the polymerization system solution through the inlet pipe. The flow velocity at that time was approximately 8 c
m/BθC and took about 6 hours to feed. After the monomer was supplied, a catalyst was added to complete the polymerization. The obtained resin was a transparent solution without turbidity, and no gel-like substance was observed. The average degree of polymerization of the resin (measured by J.K. SK 6721) was 260.0 Example 2 Example 1 was repeated using vinyl acetate instead of vinyl propionate. A transparent solution without turbidity was obtained, and the average degree of polymerization was 240.

Example 3 60 parts of vinyl chloride in the polymerization vessel of Example 1.

30 parts of vinyl propionate, 6 parts of 2-hydroxyethyl acrylate and 180 parts of ethyl acetate were charged and the temperature was raised to 65°C.

A 5% by weight solution of inglovir peroxydicarbonate catalyst in ethyl acetate was added to the polymerization vessel at a rate of 5 parts per hour to initiate polymerization. Next, a mixture of 150 parts of vinyl chloride, 15 parts of vinyl propionate, and 59 parts of 2-hydroxyethyl acrylate and metal fittings were continuously fed into the polymerization system solution into the polymerization vessel using the introduction pipe of Example 1. did. The flow rate at that time was about 7 cm/sec, and the supply took about 7 hours.

After the monomer addition was completed, a catalyst was added to complete the polymerization.

A resin solution with an average degree of polymerization of 250 and good transparency was obtained.

Example 4 Example 1 was repeated using 2-hydroxypropyl acrylate in place of 2-hydroxyethyl acrylate. A transparent solution without turbidity was obtained, and the average degree of polymerization was 250.
Met.

Comparative Example 1 Example 1 was repeated except that an inlet tube with a diameter of 1.0 as was used and the monomer was continuously fed for about 6 hours. The flow rate at this time was about 1 cyr/sea. During the polymerization, the monomer introduction tube was blocked by insoluble resin, and turbidity was observed in the polymerization solution.

Comparative Example 2 Example 1 was repeated except that the outlet of the introduction tube was placed above the liquid surface instead of in the polymerization system internal liquid so that the liquid was dripped. As the viscosity of the liquid increased, the monomer supplied later remained above the liquid level, resulting in poor mixing. The polymerization solution was observed to be cloudy.

Example 5 <Isocyanate curing reaction> OR/N co
They were blended so that the ratio was 1.

0 Bottle Life: The time required for a solution to reach a state of reverse flow in a test tube (23°C) Umbrella catalyst...
・Dibutyltin dilaurate 0 Coating film strength: The above-mentioned liquid mixture was applied to form a film. 23° (60%RH
After being left in a constant temperature room for 2 weeks, a tensile test (Takashi Seisakusho Autographe S-5,000 model, tensile speed 10 m/m1n) was conducted.

Catalyst: Dibutyltin dilaurate 0 Solvent resistance and water resistance of the coating film Solvent resistance: After drying for 2 weeks, the film was immersed in methyl ethyl ketone for 24 hours, and then the film was heated at 60°
Vacuum drying was performed for 124 hours, and the dissolution rate was determined from the following formula.

Water resistance: After drying for 2 weeks, the film was immersed in distilled water for 2 weeks, and the water absorption rate was determined using the following formula.

M weight before immersion 828) Yohishinner (butyl acetate/xylene - 1/1) was blended to obtain a coating composition with a solid content of 4&0 weight t. Coronate HL used in Example 5 was oH/N
co-171 to form a coating film. 23°C,
1. After leaving it in the 604RFi constant temperature room for one week. Tl5K-54
00. Each coating test was conducted according to K-5582.

The comparative resin in the table was polymerized by charging vinyl chloride, vinyl acetate, and maleic anhydride in a weight ratio of 70:30:1, and had an average degree of polymerization of 270.

Claims (1)

[Claims] (1) 50-80% by weight vinyl chloride monomer, 2-30%
Monomers consisting of % by weight of glycol monoester monomers of alpha, beta ethylenically unsaturated carboxylic acids and 5-40% by weight of vinyl ester monomers of saturated carboxylic acids containing 1 to 6 carbon atoms. In a copolymerization method in which all or part of the monomer is continuously supplied into the polymerization system, it is recommended to directly insert the monomer continuously supplied into the polymerization system solution at a flow rate of 5 cm/sec or more. Characterized by an average degree of polymerization of 100
A method for producing a homogeneous random copolymer having a molecular weight of 500.