JP2001019727A - Vinyl chloride resin - Google Patents

Abstract

(57) [Problem] To provide a vinyl chloride resin excellent in impact resistance, heat stability and moldability. SOLUTION: Vinyl chloride is added to 1 to 30% by weight of an acrylic copolymer having a glass transition temperature of -20 ° C or lower, which is obtained by soap-free polymerization of a radical polymerizable monomer containing (meth) acrylate as a main component. A vinyl chloride resin obtained by graft copolymerizing 99 to 70% by weight of a vinyl monomer as a main component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl chloride resin excellent in impact resistance, heat stability and moldability.

[0002]

2. Description of the Related Art Vinyl chloride resins are used in many applications as materials having excellent properties such as mechanical strength, weather resistance and chemical resistance. However, there is a drawback that when used for hard products, the impact resistance is poor.

As a method for improving these disadvantages, for example, JP-A-60-255813 discloses a vinyl chloride resin obtained by graft-copolymerizing vinyl chloride on a crosslinked acrylic copolymer. It has been proposed as a vinyl chloride resin for applications requiring impact resistance and weather resistance. However, this graft vinyl chloride resin is
Compared to a straight vinyl chloride resin, it has been found that initial coloring tends to occur during thermoforming and the thermal stability is slightly inferior. In addition, the above-mentioned grafted vinyl chloride resin also has the disadvantage that the gelling time is long due to high resin lubricity and the processing performance is inferior.

The cause of these problems is considered to be the effect of the emulsifier remaining in the vinyl chloride resin.
In a preferred method for producing an acrylic copolymer and a graft copolymer of vinyl chloride by an emulsion polymerization method disclosed so far, including JP-A-60-255813, the acrylic copolymer contains an emulsifier. It is manufactured by an emulsion polymerization method using The emulsifier used in the emulsion polymerization of the acrylic monomer is partly discharged out of the system together with the polymerization effluent during the vinyl chloride graft polymerization process, but is largely taken into the vinyl chloride resin. ing. This emulsifier is not chemically bonded to the resin, but is released from the resin during melt molding of the vinyl chloride resin to impart lubricity to the resin, or to chemically change the thermal stability of the resin. It is thought that it has been a trigger to spoil.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a vinyl chloride resin which is excellent in impact resistance, heat stability and molding workability in order to solve the above problems. .

[0006]

The vinyl chloride resin according to the present invention is an acrylic resin having a glass transition temperature of -20 ° C. or lower, which is obtained by soap-free polymerization of a radical polymerizable monomer containing (meth) acrylate as a main component. System copolymer 1
30 to 70% by weight of a vinyl monomer having vinyl chloride as a main component is graft-copolymerized to 30% by weight.

Hereinafter, the present invention will be described in detail.

The above (meth) acrylate is used for the purpose of improving the impact resistance of a vinyl chloride resin, and in order to impart flexibility at room temperature, the glass transition temperature of the homopolymer of the (meth) acrylate is used. Is preferably −20 ° C. or lower, and more preferably −140 ° C. or higher in consideration of the glass transition temperature of a polymer generally used industrially. The glass transition temperature is based on “Polymer Data Handbook (Basic Edition)” published by Baifukan and edited by the Society of Polymer Science, etc. In this specification, the (meth) acrylate is a generic term for acrylate and methacrylate.

The (meth) acrylate having a glass transition temperature of -140 to -20 ° C is not particularly limited. For example, ethyl acrylate, n-propyl acrylate,
Isopropyl acrylate, n-butyl acrylate,
i-butyl acrylate, sec-butyl acrylate, n-hexyl acrylate, n-heptyl acrylate, n-octyl (meth) acrylate, 2-methylheptyl (meth) acrylate, 2-ethylhexyl acrylate, n-nonyl (meth) acrylate, 2-methyloctyl (meth) acrylate, 2-ethylheptyl methacrylate, n-decyl (meth) acrylate,
Examples thereof include alkyl (meth) acrylates such as 2-methylnonyl (meth) acrylate, 2-ethyloctyl (meth) acrylate, and n-dodecyl methacrylate, 2-hydroxyethyl acrylate, and 2-hydroxypropyl acrylate. More than one species may be used in combination.

In the present invention, the radical polymerizable monomer other than (meth) acrylate is added for the purpose of improving the mechanical strength, chemical resistance and moldability of the vinyl chloride resin, and is not particularly limited. For example, (meth) such as methyl (meth) acrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl (meth) acrylate, and cyclohexyl (meth) acrylate
Acrylate, 2-hydroxyethyl methacrylate,
Polar group-containing vinyl monomers such as 2-acryloyloxyethyl phthalic acid, styrene, α-methylstyrene, p-
Aromatic vinyl monomers such as methylstyrene and p-chlorostyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; vinyl esters such as vinyl acetate and vinyl propionate;
More than one species may be used in combination.

Further, in the present invention, a polyfunctional monomer is added to the radical polymerizable monomer containing (meth) acrylate as a main component, if necessary, for the purpose of crosslinking the acrylic copolymer of the present invention. You may.

As the polyfunctional monomer, for example,
As di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth)
Acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane di (meth) acrylate, and the like. As tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene oxide-modified trimethylolpropane tri (Meth) acrylate, pentaeristol tri (meth) acrylate and the like can be mentioned. Other polyfunctional monomers include pentaerythritol tetra (meth) acrylate, dipentaeristol hexa (meth) acrylate, diallyl phthalate, diallyl maleate, diallyl fumarate, diallyl succinate, triallyl isocyanurate and the like. And divinyl compounds such as divinylbenzene and butadiene. These may be used alone or in combination of two or more.

The amount of the polyfunctional monomer to be added to the radical polymerizable monomer containing (meth) acrylate as a main component is preferably between 90 and 10 radical polymerizable monomers.
10 to 0% by weight of polyfunctional monomer to 0% by weight
It is preferably added, more preferably 0.1 to 5% by weight. If the addition amount of the polyfunctional monomer exceeds 10% by weight, it may be difficult to obtain impact resistance due to the excess of the crosslinking density.

The acrylic copolymer used in the present invention must have a glass transition temperature of -20 ° C. or lower. When the glass transition temperature exceeds −20 ° C., when the ambient temperature is 0 ° C. or lower, the vinyl chloride resin does not exhibit impact resistance, and cannot be used in cold regions.

The above-mentioned acrylic copolymer is obtained by soap-free polymerization of a radically polymerizable monomer containing (meth) acrylate as a main component. The method of the soap-free polymerization is not particularly limited. In order to prevent the separation of the emulsifier or the method of performing polymerization using no or dispersant at all or using a very small amount, a method in which a hydrophilic polymer such as polyacrylic acid or polyvinyl alcohol is dispersed in a system dispersed therein. A method of performing polymerization using a reactive emulsifier and the like can be mentioned. In the present invention, in order to more strictly eliminate the influence of the emulsifier, it is preferable to use no emulsifier or dispersant at all or use a very small amount to carry out polymerization.

Examples of the polymerization initiator used in the above soap-free polymerization include hydrophobic initiators such as benzoyl peroxide, lauroyl peroxide, t-butyl peroxypivalate, diisopropyl peroxydicarbonate and dioctyl peroxydicarbonate. ,
organic peroxides such as t-butyl peroxy neodecanoate and α-cumyl peroxy neodecanoate;
Azobisisobutyronitrile, 2,2-azobis-2,
An azo initiator such as 4-dimethylvaleronitrile is exemplified, and examples of the hydrophilic initiator include potassium persulfate, ammonium persulfate, aqueous hydrogen peroxide and the like. In the present invention, it is preferable to use a hydrophilic initiator that improves the dispersion stability during polymerization.

In the soap-free polymerization, a very small amount of an emulsifier or a dispersant may be added in order to improve the dispersion stability of the produced polymer particles. Surfactant,
Nonionic surfactants, partially saponified polyvinyl acetate, cellulose dispersants, gelatin and the like. In the present invention, the use of an anionic surfactant is preferable, and examples thereof include polyoxyethylene alkylphenyl ether sulfate. The amount of the emulsifier or dispersant added is preferably 0.1 part by weight or less based on 100 parts by weight of the radical polymerizable monomer. If the amount exceeds 0.1 parts by weight, the thermal stability and moldability of the vinyl chloride resin may be impaired.

In the present invention, the soap-free polymerization method includes two methods, namely, a batch polymerization method and a monomer dropping method, depending on the difference in the monomer addition method, but is not particularly limited. Here, the batch polymerization method means, for example, that ion-exchanged water and a monomer are collectively added into a polymerization reaction tank with a jacket, oxygen is removed by reducing the pressure inside the polymerization tank, and then the pressure is increased to atmospheric pressure with nitrogen. This is a method in which the polymerization system is suspended by stirring under a nitrogen atmosphere where the pressure is restored, the polymerization tank is heated to a predetermined temperature, and then a polymerization initiator is added to carry out polymerization. In addition, the monomer dropping method means, for example, that ion-exchanged water and a polymerization initiator are put into a polymerization reaction tank with a jacket, the inside of the polymerization tank is depressurized, oxygen is removed, and then the pressure is returned to atmospheric pressure with nitrogen. Under a nitrogen atmosphere, a method in which a polymerization vessel is first heated to a predetermined temperature, and then a monomer is added dropwise in a fixed amount to gradually polymerize. Further, in the monomer dropping method, a method is used in which a part of the monomer (hereinafter, referred to as a seed monomer) is added all at once in the early stage of polymerization to generate seed polymer particles, and then the remaining monomer is dropped. By changing the amount, the particle size of the produced latex can be controlled.

In the soap-free polymerization of the present invention, if necessary, one or more of various additives such as a chain transfer agent, a pH adjuster, and an antioxidant may be added.

In the present invention, the acrylic copolymer obtained by the soap-free polymerization is obtained in a latex state, and the solid content of the resin is not particularly limited. Considering the productivity of the latex and the stability of the polymerization reaction, 5 to 60% by weight is preferred.

The average resin particle diameter of the acrylic copolymer latex is not particularly limited, and may be 0.01 to 1.0.
μm is preferred. If it exceeds 1 μm, both the impact resistance and the tensile strength of the vinyl chloride resin may decrease,
If the thickness is less than 0.01 μm, the impact resistance may slightly decrease.

The above acrylic copolymer latex includes:
In order to improve the mechanical stability of the latex, a protective colloid may be added as needed after the completion of the latex polymerization reaction.

In the vinyl chloride resin of the present invention, the content of the acrylic copolymer is required to be 1 to 30% by weight, preferably 4 to 20% by weight. When the content of the acrylic copolymer is less than 1% by weight, impact resistance is insufficient, and when it exceeds 30% by weight, mechanical strength such as bending strength and tensile strength decreases.

In the present invention, the vinyl monomer containing vinyl chloride as a main component to be graft-copolymerized to an acrylic copolymer means a mixture of 50% by weight or more of vinyl chloride and a vinyl monomer copolymerizable therewith. And then
The copolymerizable monomer is not particularly limited, and includes, for example, vinyl acetate, alkyl (meth) acrylate, alkyl vinyl ether, ethylene, vinyl fluoride, maleimide, and the like. These may be used alone or in combination of two or more. Is also good.

The method of graft copolymerizing a vinyl monomer containing vinyl chloride as a main component with the acrylic copolymer is not particularly limited, and examples thereof include a suspension polymerization method, an emulsion polymerization method, a solution polymerization method, and a bulk polymerization method. Although a synthesizing method is mentioned, a suspension polymerization method is preferably used.

The dispersant used in the suspension polymerization is added to improve the dispersion stability of the acrylic copolymer latex and to efficiently carry out the graft polymerization of vinyl chloride. Acid salt, (meth) acrylate-alkyl acrylate copolymer, methylcellulose, ethylcellulose, hydroxypropylmethylcellulose, polyethylene glycol, polyvinyl acetate and partially saponified products thereof, gelatin, polyvinylpyrrolidone, starch, maleic anhydride-styrene copolymer And the like, and these may be used alone or in combination of two or more.

As the hydrophobic polymerization initiator used in the suspension polymerization, a radical polymerization initiator is suitably used, and examples thereof include lauroyl peroxide, t-butyl peroxypivalate, diisopropyl peroxydicarbonate, and dioctyl peroxy. Organic peroxides such as oxydicarbonate, t-butyl peroxy neodecanoate, α-cumyl peroxy neodecanoate, 2,2-azobisisobutyronitrile, 2,2-azobis-2,4
-Azo compounds such as dimethylvaleronitrile.

In the present invention, when a vinyl monomer containing vinyl chloride as a main component is graft-copolymerized to the acrylic copolymer, the acrylic copolymer is reduced in order to reduce the scale attached to the polymerization tank during the polymerization. A coagulant may be added to the copolymer latex. In the above suspension polymerization method, a pH adjuster, an antioxidant and the like may be added as necessary.

The polymerization degree of polyvinyl chloride in the vinyl chloride resin of the present invention is preferably from 300 to 2,000,
~ 1600 is more preferable. Even if the degree of polymerization is less than 300,
If it exceeds 2,000, the moldability may be insufficient.

When molding the vinyl chloride resin of the present invention, if necessary, a heat stabilizer, a stabilizing aid, a lubricant, a processing aid, an antioxidant, a light stabilizer, a filler, a pigment, etc. May be added and used.

Examples of the heat stabilizer include dimethyltin mercapto, dibutyltin mercapto, dioctyltin mercapto, dibutyltin malate, dibutyltin malate polymer, dioctyltin malate, dioctyltin malate polymer, dibutyltin laurate, dibutyltin Organic tin stabilizers such as laurate polymers, lead stabilizers such as lead stearate, dibasic lead phosphite, and tribasic lead sulfate, calcium-zinc stabilizer, barium-zinc stabilizer, barium- Cadmium stabilizers and the like can be mentioned.

Examples of the stabilizing aid include epoxidized soybean oil, epoxidized linseed oil, epoxidized tetrahydrophthalate, epoxidized polybutadiene, and phosphate esters.

Examples of the lubricant include montanic acid wax, paraffin wax, polyethylene wax,
Stearic acid, stearyl alcohol, butyl stearate and the like can be mentioned.

Examples of the processing aid include an acrylic processing aid which is an alkyl acrylate-alkyl methacrylate copolymer having a weight average molecular weight of 100,000 to 2,000,000, and specifically, n-butyl acrylate-methyl. Examples include methacrylate copolymers and 2-ethylhexyl acrylate-methyl methacrylate-butyl methacrylate copolymers.

Examples of the above antioxidants include phenolic antioxidants.

Examples of the light stabilizer include salicylic acid ester-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ultraviolet absorbers, and hindered amine-based light stabilizers.

Examples of the filler include calcium carbonate and talc.

Examples of the pigments include organic pigments such as azo, phthalocyanine, sulene and dye lakes.
Oxide-based, molybdenum chromate-based, sulfide / selenide-based, ferrocyanide-based inorganic pigments and the like can be mentioned.

Further, a plasticizer may be added to the vinyl chloride resin of the present invention in order to improve the processability at the time of molding. Examples thereof include dibutyl phthalate, di-2-ethylhexyl phthalate, and di-2-phthalate. Ethylhexyl adipate and the like can be mentioned.

Examples of a method for mixing these additives with the vinyl chloride resin include a method using hot blending and a method using cold blending. Examples of the molding method include an extrusion molding method and an injection molding method. A molding method, a calender molding method, a press molding method and the like can be mentioned.

Since the vinyl chloride resin of the present invention has the above-mentioned structure, it can exhibit excellent impact resistance and also excellent performance in heat stability and moldability.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” means “parts by weight”, and “%” means “% by weight”.

(Examples 1 to 3, Comparative Examples 2 and 4) (1) Preparation of Acrylic Copolymer Ion-exchanged water was put into a polymerization vessel equipped with a stirrer and a jacket, and stirring was started. Was decompressed to deoxygenate the inside of the vessel, and then the pressure was returned with nitrogen to perform replacement, and the liquid temperature in the polymerization vessel was raised to 70 ° C. In the polymerization vessel where the temperature was raised, 0.1% ammonium persulfate was added as a polymerization initiator.
After adding all parts at once, the mixture was stirred and dissolved for 15 minutes. Next, the dropping of the monomer having the composition shown in Table 1 was started, and the dropping of the monomer was completed in 2 hours. The polymerization was terminated after an aging time of 1 hour, and the solid content was about 20%.
A latex acrylic copolymer (hereinafter referred to as latex) having a particle size of 0.2 to 0.3 μm was obtained.

(2) Preparation of Vinyl Chloride Resin In a polymerization vessel equipped with a stirrer and a jacket, ion-exchanged water, a 3% aqueous solution of partially saponified polyvinyl acetate, t-butyl peroxy neodecanoate, α- Cumyl peroxy neodecanoate and the latex of the above (1) having the composition shown in Table 1 were charged all at once, and the air in the polymerization reactor was discharged by a vacuum pump. And the polymerization temperature is controlled to 57 ° C by controlling the jacket temperature.
To initiate polymerization. The pressure in the reactor is 6.0 kgf /
The completion of the reaction was confirmed by lowering to a pressure of cm 2, and the system was cooled and stopped. Thereafter, the unreacted vinyl chloride monomer is removed, and the polymer is further dehydrated and dried to obtain a polymerization degree of about 1
A vinyl chloride resin containing 2,000 polyvinyl chloride was obtained.

(3) Performance Evaluation The performance of the vinyl chloride resin of the above (2) was evaluated by the following method. The results were as shown in Table 1. Thermal stability: A heat aging test was performed according to JIS K7212. The test piece was roll-kneaded with a resin composition obtained by mixing 1.0 part of an organotin stabilizer and 0.5 part of a montanic acid lubricant with respect to 100 parts of a vinyl chloride resin at 190 ° C. for 3 minutes. The obtained roll sheet was used. The test temperature was 190 ° C., a sample was taken out in 10 minutes, and the time until initial coloring was observed was evaluated. Gelation time: Toyo Seiki Labo Plastomill (mod
el 50C150), the time for the torque to rise was measured under the conditions of a mold temperature of 190 ° C., a rotation speed of 40 rpm, and a sample filling amount of 55 g. The sample was prepared by adding 1.0 part of an organotin stabilizer, 0.5 part of a polyethylene lubricant, and 0.5 part of calcium stearate to 100 parts of a vinyl chloride resin.
A resin composition in which parts were mixed was used. The evaluated gelation time is preferably 360 seconds or less from a practical viewpoint. Impact resistance: Evaluated by a Charpy impact value measured according to JIS K 7111. The test piece was composed of 1.0 part of an organotin-based stabilizer, 0.5 part of a polyethylene-based lubricant, and 0.5 part of calcium stearate based on 100 parts of a vinyl chloride resin.
The resin composition obtained by mixing 5 parts was roll-kneaded at 200 ° C. for 3 minutes, and then press-formed at 200 ° C. for 3 minutes to produce a 3 mm-thick press plate. The measurement was performed at 23 ° C. Tensile strength: Evaluated by tensile strength measured according to JIS K 7113. The test piece was produced in the same manner as in the above Charpy impact test. The measurement was performed at 23 ° C.

(Comparative Examples 1 and 3) (1) Preparation of Acrylic Copolymer 30% of the total amount of ion-exchanged water used for polymerization, emulsifying dispersant N-08 (polyoxyethylene alkyl phenyl ether ammonium sulfate) 1 0.0 parts and a monomer having a composition shown in Table 1 were mixed and stirred to prepare an emulsion monomer. On the other hand, the remaining ion-exchanged water is put into the polymerization vessel, stirring is started, the pressure inside the polymerization vessel is reduced, and the oxygen in the vessel is deoxygenated. The temperature was raised to 70 ° C. 0.1 parts of ammonium persulfate and 10% of the above emulsified monomer were collectively charged as a seed monomer into the polymerization vessel in which the temperature was raised, and polymerization was started. Subsequently, the rest of the emulsified monomer was dropped, and the process was completed in 2 hours. The polymerization was terminated after a one-hour aging time, and the solid content was about 30% and the particle size was 0.2.
An acrylic copolymer latex of about 0.3 μm was obtained.

(2) Preparation of vinyl chloride resin A vinyl chloride resin was obtained in the same manner as in Example except that the latex of the above (1) was used.

The performance of the two types of vinyl chloride resins obtained in Comparative Examples 1 and 3 was evaluated in the same manner as in the examples. The results were as shown in Table 1.

[0049]

[Table 1]

As is clear from Table 1, the vinyl chloride resins of Examples 1 to 3 according to the present invention are excellent in impact resistance and mechanical strength, and are also excellent in thermal stability and gelling properties. .

On the other hand, instead of soap-free polymerization,
The vinyl chloride resins of Comparative Examples 1 and 3 using acrylic copolymers obtained by emulsion polymerization using an emulsifier are inferior in heat stability and gelling properties.

The vinyl chloride resin of Comparative Example 2 containing less than 1% by weight of the acrylic copolymer and Comparative Example 4 containing the acrylic copolymer having a glass transition temperature of more than −20 ° C. Impact resistance is greatly reduced.

[0053]

As described above, since the vinyl chloride resin of the present invention is excellent in impact resistance, heat stability and molding processability, pipes, outer walls, It is suitably used for applications such as soundproof walls having irregular cross sections and window frames, sashes and the like which require good formability and surface properties.

Continued on the front page F-term (reference) 4J026 AA17 AA18 AA21 AA37 AA38 AA40 AA45 AA46 AA47 AA48 AA49 AA55 AA61 AA68 AA76 AC34 AC36 BA02 BA10 BA11 BA16 BA20 BA27 BA38 BB01 BB02 BB08 DA04 DB12 DA03 DB15 DB29 GA01 GA09

Claims (1)

[Claims] 1. An acrylic copolymer having a glass transition temperature of -20.degree. C. or less obtained by soap-free polymerization of a radical polymerizable monomer containing (meth) acrylate as a main component, and vinyl chloride. A vinyl chloride resin characterized by being obtained by graft copolymerizing 99 to 70% by weight of a vinyl monomer containing as a main component.