JP2660478B2 - Chlorinated rubber and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chlorinated rubber and a method for producing the same, and more particularly, to a chlorinated rubber suitable for applications such as paints and adhesives, and a method for easily producing the same from latex.

[0002]

2. Description of the Related Art Chlorinated rubbers have been widely used in anticorrosive paints, inks, adhesives, etc., but in particular, chlorinated natural rubbers and synthetic rubbers have a chlorine content of 60% by weight or more. This is widely used as a raw material for heavy anticorrosion paints. Further, chlorinated rubber is generally produced by dissolving raw rubber in a chlorine-based solvent such as carbon tetrachloride which is inert to chlorine, and then introducing a chlorine gas to perform chlorination.

[0003] However, the use of carbon tetrachloride used in this method is likely to be restricted in the future because it is a substance that destroys the ozone layer. On the other hand, a method of chlorinating rubber in an aqueous medium has been disclosed (Japanese Patent Publication No. Sho 34).
-10195, JP-A-4-36303)
However, these methods have the drawback that the operation is complicated and the reaction efficiency is poor.

Further, a method of chlorinating in an aqueous medium using an emulsified liquid polyisopropylene as a raw material is known (JP-A-4-36303). However, in order to obtain a stable emulsion, a homogenizer or the like is used. However, there is a drawback that a mechanical operation is required and it is difficult to set the conditions.

Further, a method of chlorinating an underwater dispersion or emulsion of synthetic rubber or natural rubber is also known (Japanese Patent Application Laid-Open No. 4-46905). In this method, when chlorine gas is blown directly, the latex solidifies. Therefore, it is necessary to prepare the reaction solution in advance to be acidic, and there is a disadvantage that the operation becomes complicated. In addition, a photochlorination method of irradiating ultraviolet rays during the chlorination reaction has been proposed (JP-A-4-598).
No. 01).

[0006]

However, the above-mentioned method has the drawbacks that coagulation of the latex cannot be completely prevented, the operation is complicated, and the production of chlorinated rubber takes time. The present inventors have conducted intensive studies in order to solve the above-mentioned drawbacks, and as a result, have found that transformer-1,4
-It has been found that when a synthetic polyisoprene rubber containing 20% or more bonds is used as a raw material, extremely good results can be obtained, and the present invention has been achieved.

Accordingly, a first object of the present invention is to provide a chlorinated rubber which is suitable for applications such as paints and adhesives. A second object of the present invention is to provide a method for producing a chlorinated rubber, which can completely prevent coagulation of latex, is simple in operation, and can shorten the production time.

[0008]

SUMMARY OF THE INVENTION The above objects of the present invention are attained by providing a trans-1,4-linkage of not less than 20% and a molecular weight of at least 20%.
Was achieved by chlorinating 50,000 to 4,000,000 synthetic isoprene rubbers to adjust the chlorine content to a range of 60 to 75% by weight.

Hereinafter, the present invention will be described in more detail. The synthetic polyisoprene used as a raw material of the present invention must contain at least 20% of trans-1,4-bonds in the molecule. If the content is less than 20%, since the number of intramolecular crystals is reduced, the latex is easily coagulated during chlorination.

[0010] The molecular weight of the synthetic isoprene rubber used in the present invention, about 50,000～4,000,000 der
But preferably 100,000 to 3,000,000
It is. Such synthetic isoprene rubber, may be obtained by known polymerization methods, in particular by combining the emulsion polymerization by Ri <br/> directly, trans-1,4-bond, readily in the molecule 20 % Or more can be introduced.
Further, the content of trans-1,4-bond can be easily determined by infrared spectroscopy or the like.

In the emulsion polymerization of synthetic polyisoprene, it is desirable to use isoprene monomer as a raw material in an amount of 1 to 75% by weight based on the total charged weight. If the amount of the isoprene monomer is less than 1% by weight, the productivity in the chlorination step is poor, and if it exceeds 75% by weight, the latex becomes unstable.

As the type of the emulsifier used for the emulsion polymerization, either a nonionic surfactant or an anionic surfactant can be used. Examples of the nonionic surfactant include polyoxyethylene-polyoxypropylene condensate, polyoxyalkylene alkyl ether, polyoxyalkylene nonyl phenol ether, sorbitan fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, and polyoxyalkylene glycerin fatty acid ester. Can be

Examples of the anionic surfactant include higher alcohol sulfate, alkylbenzene sulfonate, polyoxyalkylene alkyl sulfate, polyoxyalkylene alkylphenyl sulfate, dialkyl sulfosuccinate and the like. The amount of these surfactants used is
The amount is preferably 0.1 to 12 parts by weight, more preferably 2 to 6 parts by weight, based on 100 parts by weight of the raw rubber. If the amount of the surfactant is less than 0.1 part by weight, the stability of the latex becomes poor, and if it exceeds 12 parts by weight, the emulsion polymerization does not have a good effect.

In the present invention, if necessary, an unsaturated aliphatic carboxylic acid may be added at the time of polymerization in order to improve the stability of the latex. Examples of such an acid include acrylic acid, methacrylic acid, maleic acid, and maleic anhydride. Its usage is
It is preferably 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the raw rubber component. If the amount used is less than 0.5 part by weight, it cannot contribute to the stability of the latex, and if it exceeds 10 parts by weight, the effect is not improved.

[0015] The initiator of the emulsion polymerization depends on the reaction conditions.
Although it can be used by appropriately selecting from known ones, it is particularly preferable to use an organic peroxide, or ammonium persulfate or potassium persulfate. By such an emulsion polymerization, 20 trans-1,4-bonds are present in the molecule.
% Of synthesized polyisoprene rubber latex can be easily obtained.

The latex used in the chlorination reaction in the present invention is preferably used in the range of 1 to 20% by weight based on the total charged amount. When the concentration is higher than this, the raw material latex may be diluted and used as needed. When the latex concentration during the chlorination reaction is less than 1% by weight, the productivity of the chlorinated rubber decreases, and when it exceeds 20% by weight, the reaction efficiency increases because the viscosity of the reaction solution increases with the progress of the chlorination. Is not preferred.

As the emulsifier used for the chlorination reaction, it is usually sufficient to use the emulsifier contained in the raw material latex as it is, but if necessary, a surfactant may be further added. The photochlorination reaction is preferably performed at a temperature in the range of 0 to 100C. If the reaction temperature is lower than 0 ° C., the medium may be frozen, and even if the reaction is performed at a temperature higher than 100 ° C., the reaction is not particularly accelerated.

The photochlorination is performed by irradiating ultraviolet rays simultaneously with the introduction of chlorine gas. By using chlorine gas and ultraviolet light together, chlorine is efficiently introduced at the same time as the rubber molecules are cut, so that the reaction time can be shortened. Further, by sufficiently introducing oxygen into the reaction system, the chlorination can proceed more efficiently.

In the chlorination, the chlorine content is 60 to 75% by weight.
It is performed so that it is in the range of. When the chlorine content is less than 60% by weight, it is difficult to uniformly dissolve in an organic solvent such as toluene when used in a paint or the like. On the other hand, when the chlorine content exceeds 75% by weight, the solubility in an organic solvent is remarkably reduced, so that it is preferable. Absent. The pressure in the reactor when supplying chlorine gas may be normal pressure or may be under pressure. The chlorinated rubber of the present invention thus obtained has a quality equal to or higher than that of the rubber obtained by the conventional method, and is therefore suitable for applications such as paints and adhesives.

[0020]

The chlorinated rubber of the present invention has a performance equal to or higher than that of a conventional product, and thus can be suitably used for applications such as paints and adhesives. Further, the method for producing a chlorinated rubber of the present invention can be chlorinated in an aqueous medium without coagulating latex, does not require complicated operations as compared with the conventional method, and can improve workability and production efficiency. In addition, the manufacturing time can be reduced.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.
It should be noted that all the blending parts in the following examples represent parts by weight.

Production Example A 100-liter pressure-resistant glass reaction vessel equipped with a stirrer, a pressure gauge, a thermometer and an internal injection valve was charged with water 100.
Parts, 3.6 parts of acrylic acid, sodium lauryl sulfate
4 parts, 0.8 parts of potassium persulfate and 0.8 parts of potassium chloride
Then, the mixture was sealed, and stirred well. Next, 80 parts of isoprene was added to the reaction vessel through an injection valve,
For 12 hours to carry out an emulsion polymerization reaction. The polymerization conversion is 9
The trans-1,4-linkage content was 60%.

Example 1 4.5 kg of the synthetic isoprene latex (average molecular weight: 2,500,000, solid content: 40% by weight, trans-1,4-bond content: 60%) obtained in the above production example was added to water. 4
0.5 kg was added and stirred well. The diluted latex was charged into a reactor having an internal volume of 50 liters equipped with a stirrer, a high-pressure mercury lamp (450 W), a thermometer, and a chlorine supply valve. After sufficiently purging chlorine into the gas phase, the reaction was started at room temperature by simultaneously irradiating ultraviolet rays while introducing chlorine through a valve, and the reaction was carried out while increasing the temperature to 100 ° C. After a lapse of 14 hours from the start of the chlorination reaction, the reaction solution was filtered, and the contents were washed with water and dried to obtain a chlorinated rubber as a white powder. This chlorinated rubber had a chlorine content of 65% by weight and was easily dissolved in toluene.

Example 2 The trans-1,4-bond content of the synthetic isoprene latex used in Example 1 was 58%, the gas phase was purged with oxygen instead of chlorine, and the chlorination reaction was carried out for 12 hours. A chlorinated rubber was obtained in the same manner as in Example 1 except for the above. The chlorine content and toluene solubility of the obtained chlorinated rubber were exactly the same as in Example 1.

Example 3 Example 1 was repeated except that the trans-1,4-bond content of the synthetic isoprene latex used in Example 1 was 30%.
A chlorinated rubber was obtained in exactly the same manner as described above. The chlorine content and toluene solubility of the obtained chlorinated rubber were exactly the same as in Example 1.

Comparative Example 1 An emulsion of synthetic isoprene latex (average molecular weight: 2,
1,000,000, solid content concentration 60% by weight, trans-
3 kg, anionic surfactant (Perex TR, manufactured by Kao) 50 g, and water 3
Add 0 liter and stir well, then add hydrochloric acid to pH
Was adjusted to 1. When chlorination reaction was started by irradiating ultraviolet rays at the same time as introducing chlorine into this preparation, about 1
After a lapse of time, large lumps were formed, and good chlorinated rubber could not be obtained.

Comparative Example 2 In the same apparatus as in Example 1, 3 kg of natural rubber latex (Soctex-CC, solid content: 60% by weight, trans-1,4-bond content: 10% or less), nonionic surfactant (Emanon) 3199, manufactured by Kao Corporation) and 90 liters of water, and 30 liters of water, and the mixture was stirred well.
Was prepared. When chlorination reaction was started by irradiating ultraviolet rays at the same time as introducing chlorine into this prepared solution, a large coagulated product was formed after about 1 hour, and a good chlorinated rubber could not be obtained.

Comparative Example 3 A chlorinated rubber was obtained in the same manner as in Example 1 except that the chlorine content was changed to 80% by a chlorination reaction. The obtained chlorinated rubber had insufficient solubility in toluene.

Comparative Example 4 A chlorination reaction was started in exactly the same manner as in Example 1 except that no ultraviolet light was irradiated. After about 4 hours (chlorine content: 52%), a high-pressure mercury lamp (450 W) was used. Was turned on, and the chlorination reaction was continued for about 14 hours. As a result, the obtained chlorinated rubber had insufficient solubility in toluene.

Comparative Example 5 2 kg of natural rubber (RSS1, Mooney viscosity 50) and 40 liters of carbon tetrachloride were charged into a glass-lined reactor having an internal volume of 50 liters and melted at 75 ° C.
Introduce chlorine gas at a reaction temperature of 75 ° C while irradiating light,
The chlorination reaction was performed for about 15 hours. The obtained reaction solution was subjected to steam distillation and then dried to obtain a chlorinated rubber. The chlorinated rubber had a chlorine content of 68% by weight and was easily dissolved in toluene.

Test Results The chlorinated rubbers obtained in Examples 1 to 3 and Comparative Example 5 were kneaded according to the following formulation to prepare coatings. This paint was spray-painted on a sandblasted plate treated with inorganic Zn to perform a performance test. Table 1 shows the results. As shown in Table 1, when used as a paint, the chlorinated rubber obtained by the present invention (Examples 1 to 3) is superior to the chlorinated rubber obtained by the conventional method (Comparative Example 5). It turns out that there is.

[Table 1] ◎ indicates extremely good, は indicates good, Δ indicates slightly good, and × indicates bad.

(1) Paint formulation Chlorinated rubber: 100 parts by weight Chlorinated paraffin (A-40): 45 parts by weight Titanium dioxide: 125 parts by weight Stabilizer: 2.5 parts by weight Xylene: 250 parts by weight Xylene is additionally used)

(2) Test method Adhesion: Cross-cut test (2 mm), 7 days later Salt water spray test: 5% aqueous sodium chloride solution is sprayed at 35 ° C., 30 days later Moisture resistance: 50 ° C., 100% RH, 30 days later Alkaline: immersed in 3% aqueous sodium hydroxide solution, 3
After 0 days Accelerated weathering resistance: After 1000 hours of sunshine weather meter

Claims (3)

(57) [Claims] 1. A synthetic isoprene rubber having a molecular weight of 50,000 to 4,000,000 containing not less than 20% of trans-1,4-linkage is chlorinated to have a chlorine content of 60 to 75.
A chlorinated rubber characterized by being adjusted to the range of weight%. 2. A synthetic isoprene rubber having a trans-1,4-bond content of 20% or more and a molecular weight of 50,000 to 4,000,000 is irradiated with chlorine gas while irradiating ultraviolet rays in an aqueous medium. By chlorinating, the chlorine content becomes 6
A method for producing a chlorinated rubber, wherein the amount is in the range of 0 to 75% by weight. 3. The method for producing a chlorinated rubber according to claim 2, wherein the synthetic isoprene rubber is directly synthesized by emulsion polymerization.