JPH0446905A - Production of chlorinated rubber - Google Patents

Abstract

PURPOSE:To obtain the title rubber excellent in anti-corrosiveness and driability and soluble in an organic solvent in an aqueous medium by preparing a dispersion of rubber particles by subjecting a dispersion or emulsion of a synthetic rubber or a natural rubber to a specified treatment and chlorinating the rubber at a specified C1 content. CONSTITUTION:A dispersion of rubber particles is prepared by adding a dispersion or emulsion of a synthetic rubber or a natural rubber (e.g. natural rubber latex) to an aqueous acid solution (e.g. 2% aqueous hydrochloric acid solution) in the presence of a surfactant (e.g. nonionic surfactant), and the rubber is chlorinated at a Cl content of 55-75wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing chlorinated rubber, and more specifically to a method for producing chlorinated rubber with excellent corrosion resistance and drying properties in a wooden surface.

[Prior art and problems to be solved by the invention] Highly chlorinated polymers such as natural rubber and synthetic polyisoprene, which have a chlorine concentration of 55% or more (on a weight basis, the same applies hereinafter), are It is excellent as a vehicle for paints, and is widely used as a raw material for heavy-duty corrosion-resistant paints with drying properties, a vehicle for inks, and a raw material for adhesives for vulcanized rubber.

Conventionally, polyisoprene was mainly chlorinated by dissolving it in a chlorinated solvent and then adding chlorine, but in recent years, due to global environmental issues, the use of chlorinated solvents has been restricted, and alternatives have been developed. Therefore, chlorination in an aqueous medium is required.

A method of chlorinating a polyolefin in an aqueous dispersion or emulsion state in an aqueous medium is known. When rubber-like polyolefin is chlorinated to about 20-50% weight, the chlorination is carried out in an aqueous dispersion system, using anti-aggregation agents such as various surfactants, and strictly controlling the polyolefin's melting point and reaction temperature. Chlorination is carried out in accordance with the regulations
2-60403, JP-A-63-128005, etc.).

A method is also known in which polyolefin with a molecular weight of 15,000 or more is made into fine particles and chlorinated in an aqueous suspension (
(Japanese Patent Publication No. 40-15660), this chlorinated product does not dissolve uniformly in ordinary organic solvents, making it difficult to use as a paint for heavy defense lines.

On the other hand, polymer polyolefin and oxidized polyolefin wax are melt-mixed and pulverized into an alkaline aqueous solution, and the resulting spherical particles are chlorinated to a chlorine concentration of 50% or less in an aqueous dispersion at a temperature of 70 to 80°C. Although there is a method (Japanese Patent Publication No. 5B-12883), this chlorinated product is insoluble in toluene, which is a common organic solvent.

An object of the present invention is to provide a method for uniformly chlorinating highly chlorinated rubber soluble in organic solvents, which can be used as a heavy-duty corrosion-resistant paint, in an aqueous medium without fear of particle aggregation. .

[Means to solve the problem]

The present inventors have completed the present invention as a result of intensive research to solve the above problems.

That is, the method for producing chlorinated rubber of the present invention involves preparing a dispersion of fine rubber particles by adding a dispersion or emulsion of synthetic rubber or natural rubber to an acidic aqueous solution in the presence of a surfactant; After that, chlorine concentration 55-75
It is characterized by being chlorinated to %.

The raw material synthetic rubber or natural rubber used in the present invention is polyisoprene having isoprene units. The above-mentioned polyisoprene can basically be produced by any method or microstructure, including natural rubber whose main component is polyisoprene, synthetic polyisoprene rubber, modified polymers in which hydroxyl groups and carboxylic acid groups are introduced into polyisoprene, Grafted polyisoprene grafted with maleic acid, maleic anhydride, succinic acid, etc. can also be used.

The molecular weight of the synthetic rubber or natural rubber of the present invention is approximately 30,000 to 4,000,000, preferably 50,000 to 3,000,000. Those with a molecular weight of less than 30,000 are chlorinated. Since the resulting product has no cohesive force, it has insufficient film strength when made into a paint, making it impractical, and even when used as a raw material for adhesives, etc., it does not exhibit sufficient strength. When the molecular weight exceeds 4,000,000, the viscosity of the chlorinated product becomes too high and it is unsuitable as a raw material for paints.

The synthetic rubber or natural rubber dispersion or emulsion of the present invention is obtained by dispersing or emulsifying synthetic rubber or natural rubber in water. Dispersion or emulsification can be carried out using conventional methods; for example, in the case of natural rubber, latex collected from tree sap and stabilized may be used as is. Further, an emulsion obtained by emulsifying agglomerated natural rubber or synthetic rubber may also be used. As the emulsion, it is also possible to use one obtained by directly emulsifying and dispersing the rubber, or one obtained by dissolving the rubber in a solvent, emulsifying and dispersing it, and then removing the solvent to form an emulsion silan.

The average particle diameter of the particles of the synthetic rubber or natural rubber dispersion or emulsion of the present invention is preferably 150 μm or less, preferably 100 μm or less. If it exceeds 150μ, the chlorinated product becomes non-uniform, with some parts soluble in organic solvents such as toluene and others not.

In the production method of the present invention, the above dispersion or emulsion is added to an acidic aqueous solution. Water is made acidic by adding hydrochloric acid water, introducing hydrochloric acid gas, introducing chlorine gas, etc., and the acid concentration may be in a saturated state to a slightly acidic state.

A suitable pH is 1 to 7.

The dispersion or emulsion is added to the acidic aqueous solution in the presence of a surfactant. The surfactant can be used as is if the surfactant originally contained in the dispersion or emulsion is effective, but a new surfactant may be added.

Suitable surfactants for use in the present invention are nonionic surfactants and anionic surfactants.

Examples of nonionic surfactants include polyoxyethylene polyoxypropylene condensates, polyoxyalkylene alkyl ethers, polyoxyalkylene nonylphenol ethers, sorbitan fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, polyoxyalkylene glycerin fatty acid esters, etc. Preferably, the HLB is 11 or more.

Further, as the anionic surfactant, higher alcohol sulfates, alkylbenzene sulfonates, alkyl phosphate salts, polyoxyalkylene sulfates, dialkyl sulfosuccinates, etc. can be used.

Cationic surfactants are not preferred because emulsilane itself has poor stability and produces insoluble matter during chlorination.

Furthermore, acrylic acid polymers, sodium naphthenate, sodium stearate, etc. may be used as emulsilylated agents.

The amount of surfactant used is 0.1 to 7 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the raw rubber component. If it is less than 0.1 part by weight, the dispersion system will not be stable and will tend to aggregate before or after starting chlorination, and if it exceeds 7 parts by weight, it will adversely affect the chlorination in the subsequent process. , particle agglomeration and non-uniform chloride formation.

The dispersion or emulsilylated synthetic rubber or natural rubber is added to the acidic aqueous solution by dropwise addition or spraying, and the concentration of the prepared rubber particle dispersion is approximately 0.5 to 30% by weight. preferable.

The chlorination of the present invention is preferably carried out at a chlorination temperature of 0 to 90°C; below 0°C, problems such as freezing of the medium will occur;
If the temperature exceeds 0°C, polymer fusion may occur, which is not preferable.

The chlorination of the present invention is carried out to a chlorine concentration of 55 to 75%. 5
If it is less than 5%, it will not dissolve in organic solvents such as toluene, and
Incompatibility with plasticizers and other resins. Moreover, if it exceeds 75%, the chlorinated resin will not dissolve in the solvent.

In the chlorination of the present invention, chlorine can be effectively utilized by using a radical initiator or by performing it under ultraviolet irradiation. The supply of chlorine may be either a feed type or a closed type, and may be carried out under normal pressure or under increased pressure.

〔Effect of the invention〕

By the production method of the present invention, a chlorinated rubber that is uniformly dissolved in an organic solvent and is useful as a raw material for heavy-duty anti-corrosion paints, vehicles for inks, and raw materials for adhesives can be obtained in an aqueous medium.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

Example 1 2% hydrochloric acid water 6001 was placed in a cylindrical reaction tank with an IP volume, equipped with a stirrer, a temperature needle, a chlorine feed nozzle, and capable of being irradiated with ultraviolet rays from the outside using a mercury lamp, and polyoxyethylene polyoxypropylene condensation was carried out. Mono-nonionic surfactant (
Adekanol Nl'-1200 manufactured by Asahi Denka Kogyo Co., Ltd.:
B15) 1.0 g was added and stirring was started at 25°C (pH 4).

When 50g of natural rubber latex (average molecular weight 2,000.000; average particle size 80μ, solid content concentration 60%) stabilized with a small amount of ammonia water is added little by little over 20 minutes into the water, Once the fine particles were in a dispersed state, chlorine gas was blown in at a rate of 50 g/hour.

After 5 hours of chlorination in this manner, the particles were separated by filtration, washed with water and dried under reduced pressure at 50°C.

No fusion of particles was observed during the reaction, and the particles remained fine even after filtration and drying. The chlorine concentration of the dried chlorinated product is 64%, and the viscosity of a 20% toluene solution of this product is 40 cp.
s/25°C and was uniform. Furthermore, a film obtained by applying the solid-liquid to a glass plate and drying it was also uniformly transparent.

Example 2 2% hydrochloric acid water 6001 was placed in a cylindrical reaction tank with a volume of 11, equipped with a stirrer, a thermometer, a chlorine feed nozzle, and capable of being irradiated with ultraviolet rays from the outside using a mercury lamp, and polyoxyethylene polyoxypropylene was added. Condensate nonionic surfactant (
Adekanol NP-1200 manufactured by Asahi Denka Kogyo Co., Ltd.:
1.0 g of HLB15) was added and stirring was started at 40°C (pH 4).

In this, an emulsion of synthetic polyisoprene rubber (average molecular weight 1.000; average molecular weight 1.000;
When 50 g (average particle diameter 30 μm, solid content concentration 60%) was added little by little by spraying, the fine particles became dispersed in water, and chlorine gas was blown into the water at a rate of 50 g/hour.

After 6 hours of chlorination in this manner, the particles were separated by filtration, washed with water and dried under reduced pressure at 50°C.

No fusion of particles was observed during the reaction, and the particles remained fine even after filtration and drying. The chlorine concentration of the dried chlorinated product is 66%, and the viscosity of a 20% toluene solution of this product is 20 c.
ps/25°C and was uniform. Furthermore, a film obtained by applying the solid-liquid to a glass plate and drying it was also uniformly transparent.

Example 3 Volume is 1! Then, 1% hydrochloric acid water 6001 was poured into a cylindrical reaction tank equipped with a stirrer, a thermometer, and a chlorine feed nozzle, and which could be irradiated with ultraviolet rays from the outside using a mercury lamp. Company manufactured ADEKA COL EC-4500: HLB15) 1.0 g
was added, and stirring was started at 25°C (pH 4).

In this, an emulsion of synthetic polyisoprene rubber (average molecular weight 3,000,000; average molecular weight: 3,000,000;
Average particle size: 30μ, solid content concentration: 60%) 50g, 20g
When added little by little over several minutes, fine particles became dispersed in the water. Next, the temperature was raised to 70°C, and chlorine gas was blown in at a rate of 50 g/hour.

After 5 hours of chlorination in this manner, the particles were separated by filtration, washed with water and dried under reduced pressure at 50°C.

No fusion of particles was observed during the reaction, and the particles remained fine even after filtration and drying. The chlorine concentration of the dried chlorinated product is 65%, and the viscosity of a 20% toluene solution of this product is 25 cp.
s/25°C and was uniform. Furthermore, a film obtained by applying the solid-liquid to a glass plate and drying it was also uniformly transparent.

Comparative Example 1 Polyoxyethylene polyoxypropylene condensate nonionic surfactant (Adekanol NP-1600 manufactured by Asahi Denka Kogyo Co., Ltd.: HLB18) 2 was added to 800 g of water at 50°C.
g, Sodium sulfosuccinate anionic surfactant (ADEKA COL EC-4500 manufactured by Asahi Denka Kogyo Co., Ltd.) 1
g, and the rotation speed of the homogenizer was set to 1100 Orr.
As p, 30 g of synthetic isoprene with a molecular weight of 2,000,000 dissolved in 800 g of toluene at 70°C is
It was dripped over several minutes. After the addition, mixing was continued for an additional 60 minutes at the same rotation speed. The resulting emulsion was desolvented under reduced pressure at 50°C to completely remove toluene, and the weight was adjusted to 330 g. The average particle size of this emulsion was 180μ.

This product was immediately dispersed and chlorinated in exactly the same manner as in Example 1. No fusion of particles was observed during the reaction, but after filtration and drying, the particles were in the form of coarse particles. The chlorine concentration of the dried chloride is 65%, and 2
0% toluene? The viscosity of the liquid was 25 cps/25°C and was uniform. However, the film obtained by applying the solid-liquid to a glass plate and drying it was somewhat opaque.

Comparative Example 2 Volume is 1! Distilled water 6001 was put in a cylindrical reaction tank equipped with a stirrer, a thermometer, and a chlorine feed nozzle, and which could be irradiated with ultraviolet rays from the outside using a mercury lamp. 50 g of the natural rubber latex used in Example 1 was added thereto, and the temperature was heated at 40°C. Stirring was started.

When chlorine gas was blown in at a rate of 50 g/hour, nodules with a particle size of about 2 to 3III11 were generated after 10 minutes. Chlorine feed was continued for 7 hours.

Even after filtration and drying, the particle size was 2 to 3Il111. The chlorine concentration of the dried chlorinated product was 65%;
The 0% toluene solution was in a non-uniform state with a mist-like substance present.

Comparative Example 3 Distilled water 6001 was put into a cylindrical reaction tank having a volume of tp, equipped with a stirrer, a thermometer, a chlorine feed nozzle, and capable of being irradiated with ultraviolet rays from the outside using a mercury lamp.
2 g of -1200 and 50 g of the synthetic rubber emulsion used in Example 3 were added, and stirring was started at 20°C.

When chlorine gas is blown into this at a rate of 50g/hour,
After 30 minutes, nodules with a particle size of about 2 to 3+v+ were generated. If chlorine feed is continued as it is, after 60 minutes, 1
It has become a big group of people. I tried to wash a part of this with methanol and dry it to make a 20% toluene solution, but it hardly dissolved.

The chlorinated rubber of the present invention obtained in Examples 1 to 3, and the chlorinated rubber manufactured by the carbon tetrachloride solvent method for comparison (ADEKA Chlorinated Rubber CR-20: molecular weight 2.OOo, 000: raw material natural rubber, chlorine Concentration 65%, 20% toluene solution viscosity 20
A paint was prepared according to the following formulation from (cps/25°C) and applied to a mild steel plate under the following coating and drying conditions, and its physical properties were evaluated.

The results are shown in Table 1 below.

<Paint formulation> Resin 20.3% Toyobarax"150 8.7JR-500 (
TiOz) 21.0 xylene
50.0 (Additionally, xylene is used to adjust paint viscosity) <Coating and drying conditions> ■5PCC-SB (JIS G-3141) mild steel plate used (0.6X50X150 am; "280 grinding ll)■
Steel plate cleaning: Chloroform → toluene cleaning■ Application: Bar coater 050 (0,05+u+) ■Drying: 48
Time Room temperature setting Rumor: 60°C Chlorinated rubber (ADEKA Chlorinated Rubber C
Ink was prepared from R-20) according to the following formulation, applied to art paper and aluminum foil using a NllL12 bar coater, and its physical properties were evaluated.

The results are shown in Table 2 below.

<Ink formulation> Resin (100%> 13.3% Carbon black 3.4 Toluene 88.3

Claims (1)

[Claims] A dispersion of rubber particles is prepared by adding a dispersion or emulsion of synthetic rubber or natural rubber to an acidic aqueous solution in the presence of a surfactant, and then chlorinated to a chlorine concentration of 55 to 75% by weight. A method for producing chlorinated rubber characterized by: