JPH06306105A - Chlorinated rubber and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a chlorinated rubber suitable for use in a coating, an adhesive, etc., by chlorinating a synthetic isoprene rubber contg. trans-1,4-bonds at least in a specific amt. to control the chlorine content thereof in a specified range. CONSTITUTION:A synthetic polyisoprene rubber having at least 20% trans-1,4- bonds is prepd. by emulsion polymn. or the like of isoprene monomer while using a nonionic surfactant (e.g. a polyoxyalkylene alkyl ether) or an anionic surfactant (e.g. a salt of an alkylbenzenesulfonic acid). The synthetic polyisoprene rubber is then chlorinated in an aq. medium with chlorine gas introduced thereinto while irradiating it with UV radiation to obtain a chlorinated rubber having a controlled chlorine content of 60 to 75wt.%. According to the foregoing procedure, the resulting latex can be perfectly prevented from coagulating, and the chlorinated rubber can therefore be simply and easily manufactured in a short time.

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 it from latex.

[0002]

2. Description of the Related Art Chlorinated rubber has hitherto been widely used in anticorrosion paints, inks, adhesives and the like. In particular, natural rubber and synthetic rubber are chlorinated so that the chlorine content is 60% by weight or more. These are widely used as raw materials for coatings for heavy anticorrosion. The chlorinated rubber is generally produced by a method in which a raw material rubber is dissolved in a chlorine-based solvent such as carbon tetrachloride which is inert to chlorine, and then chlorine gas is introduced to perform chlorination.

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

Further, a method of using an emulsified liquid polyisopropylene as a raw material and chlorinating in an aqueous medium is known (Japanese Patent Laid-Open No. 4-36303), but a homogenizer or the like for obtaining a stable emulsion is used. However, there is a drawback in that it is difficult to set the conditions in addition to requiring mechanical operation by.

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

[0006]

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

Therefore, a first object of the present invention is to provide a chlorinated rubber 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 the coagulation of latex, has a simple operation, and can shorten the production time.

[0008]

The above objects of the present invention are to chlorinate a synthetic polyisoprene rubber containing 20% or more of trans-1,4-bonds so that the chlorine content is 60 to 60%.
The present invention has been achieved by a chlorinated rubber characterized by being adjusted to a range of 75% by weight and a method for producing the same.

The present invention will be described in more detail below. The synthetic polyisoprene used as the raw material of the present invention is required to contain 20% or more of trans-1,4-bond in the molecule. This is because if it is less than 20%, the number of intramolecular crystals is reduced and the latex is likely to coagulate during chlorination.

The molecular weight of synthetic polyisoprene is about 50,
It is preferably about 000 to 4,000,000, and more preferably 100,000 to 3,000,000.
It is 0. Such synthetic polyisoprene can be obtained by a known polymerization method, but trans-1,4-, especially by direct synthesis by an emulsion polymerization method.
The bond can be easily introduced into the molecule by 20% or more. The content of trans-1,4-bond can be easily determined by infrared spectroscopy or the like.

When emulsion-polymerizing the synthetic polyisoprene, the isoprene monomer used as a raw material is preferably used in an amount of 1 to 75% by weight based on the total charged weight. When the isoprene monomer is less than 1% by weight, the productivity in the chlorination step is poor, and when it exceeds 75% by weight, the latex becomes unstable.

As the type of emulsifier used for emulsion polymerization, either a nonionic surfactant or an anionic surfactant can be used. Examples of nonionic surfactants include polyoxyethylene-polyoxypropylene condensates, polyoxyalkylene alkyl ethers, polyoxyalkylene nonylphenol ethers, sorbitan fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, and polyoxyalkylene glycerin fatty acid esters. To be

Examples of the anionic surfactant include higher alcohol sulfates, alkylbenzene sulfonates, polyoxyalkylene alkyl sulphates, polyoxyalkylene alkyl phenyl sulphates and dialkyl sulfosuccinates. The amount of these surfactants used is
The amount is preferably 0.1 to 12 parts by weight, and more preferably 2 to 6 parts by weight, based on 100 parts by weight of the raw rubber. When the amount of the surfactant used is less than 0.1 part by weight, the stability of the latex becomes poor, and conversely, when it exceeds 12 parts by weight, the emulsion polymerization does not bring about a good effect.

Further, in the present invention, in order to improve the stability of the latex, an unsaturated aliphatic carboxylic acid may be added during the polymerization, if necessary. Examples of such an acid include acrylic acid, methacrylic acid, maleic acid, maleic anhydride and the like. The usage is
The amount 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 conversely if it exceeds 10 parts by weight, the effect is not improved.

The emulsion polymerization initiator may be selected depending on the reaction conditions.
It can be appropriately selected from known ones and used, but it is particularly preferable to use an organic peroxide, or ammonium persulfate or potassium persulfate. By such emulsion polymerization, 20 trans-1,4-bonds are present in the molecule.
It is possible to easily obtain a synthesized polyisoprene rubber latex containing at least 100% by weight.

The latex used for the chlorination reaction in the present invention is preferably used in the range of 1 to 20% by weight based on the total amount charged. If this concentration is exceeded, the raw latex may be diluted before use. If the latex concentration during the chlorination reaction is less than 1% by weight, the productivity of the chlorinated rubber will decrease, and if it exceeds 20% by weight, the viscosity of the reaction solution will increase with the progress of chlorination and the reaction efficiency will decrease. Is not preferred.

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

Photochlorination is carried out by introducing chlorine gas and irradiating ultraviolet rays at the same time. By using chlorine gas and ultraviolet rays together, chlorine can be efficiently introduced at the same time as the cutting of the rubber molecule, so that the reaction time can be shortened. Further, by sufficiently introducing oxygen into this reaction system, chlorination can be more efficiently progressed.

Chlorination has a chlorine content of 60 to 75% by weight.
To be within the range. When the chlorine content is less than 60% by weight, it is difficult to uniformly dissolve it in an organic solvent such as toluene when it is used for paints, and when it exceeds 75% by weight, the solubility in the organic solvent is significantly lowered, which is preferable Absent. The pressure in the reaction device when chlorine gas is supplied 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 suitable for applications such as paints and adhesives.

[0020]

EFFECTS OF THE INVENTION The chlorinated rubber of the present invention has performance equivalent to or better than that of conventional products, 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 chlorinate in an aqueous medium without coagulating the latex, does not require a complicated operation as compared with the conventional method, and can improve workability and production efficiency. In addition, the manufacturing time can be shortened.

[0021]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.
In addition, all compounding parts in the following examples represent parts by weight.

Production Example A pressure-resistant glass reaction vessel having an internal volume of 1 liter equipped with a stirrer, a pressure gauge, a thermometer and an internal injection valve was charged with 100 parts of water.
Parts, acrylic acid 3.6 parts, sodium lauryl sulfate 2.
4 parts, potassium persulfate 0.8 parts and potassium chloride 0.8
Parts were added and the mixture was sealed and stirred well. Next, 80 parts of isoprene was added into the reaction vessel through an injection valve, and the temperature was 60 ° C.
The emulsion polymerization reaction was carried out for 12 hours. Polymerization conversion rate is 9
6%, and the trans-1,4-bond content was 60%.

Example 1 4.5 Kg of 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, water Four
0.5 Kg was added and well stirred. This diluted latex was put into a reactor having an internal volume of 50 liters, which was equipped with a stirrer, a high pressure mercury lamp (450 W), a thermometer and a chlorine supply valve. After sufficiently purging the gas phase with chlorine, while introducing chlorine through a valve, ultraviolet rays were simultaneously irradiated to start the reaction at room temperature, and the reaction was carried out while the temperature was raised to 100 ° C. After 14 hours had passed 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 performed 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 changed to 30%.
A chlorinated rubber was obtained by the same method 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, obtained by the phase inversion emulsification method) was placed in the same apparatus as in Example 1.
, 000,000, solid content concentration 60% by weight, trans-
1,4-bond content 10% or less) 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 add pH
Was adjusted to 1. When chlorine was introduced into this preparation liquid and ultraviolet rays were irradiated at the same time to start the chlorination reaction, 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 (Emanone) was used. 90 g (3199, manufactured by Kao) and 30 liters of water are added and well stirred, and hydrochloric acid is further added to adjust the pH to 1
Was prepared. When chlorine was introduced into this preparation liquid and at the same time ultraviolet rays were irradiated to start the chlorination reaction, a large coagulated product was generated 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 adjusted to 80% by the chlorination reaction. The obtained chlorinated rubber had insufficient solubility in toluene.

Comparative Example 4 A chlorination reaction was started by the same method as in Example 1 except that no ultraviolet ray was irradiated, and after about 4 hours (chlorine content 52%), a high pressure mercury lamp (450 W) was used. When was turned on and the chlorination reaction was continued for about 14 hours, the obtained chlorinated rubber had insufficient solubility in toluene.

Comparative Example 5 2 kg of natural rubber (RSS No. 1, Mooney viscosity 50) and 40 liters of carbon tetrachloride were placed in a glass-lined reactor having an internal volume of 50 liters and melted at 75 ° C.
Chlorine gas was introduced at a reaction temperature of 75 ° C while irradiating light,
The chlorination reaction was carried out for about 15 hours. The obtained reaction liquid was steam distilled and then dried to obtain a chlorinated rubber. The chlorine content of this chlorinated rubber was 68% by weight, and it easily dissolved in toluene.

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

[Table 1] ⊚ is extremely good, ◯ is good, Δ is slightly good, and x is 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 (when adjusting the viscosity of the paint) (Additional use of xylene)

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

Claims (3)

[Claims] 1. A chlorinated product obtained by chlorinating a synthetic polyisoprene rubber containing 20% or more of trans-1,4-bonds to adjust the chlorine content to a range of 60 to 75% by weight. Rubber. 2. A synthetic polyisoprene rubber containing 20% or more of trans-1,4-bonds is chlorinated by introducing chlorine gas while irradiating ultraviolet rays in an aqueous medium.
A method for producing a chlorinated rubber, wherein the chlorine content is in the range of 60 to 75% by weight. 3. The method for producing a chlorinated rubber according to claim 2, wherein the synthetic polyisoprene rubber is directly synthesized by emulsion polymerization.