DE3321902A1 - Process for the preparation of chloroprene rubber - Google Patents

Description

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The invention relates to a process for the production of chloroprene rubber, which has a very low tendency to Formation of impurities on the metal mold (following referred to as metal mold contamination) that is used to compression mold and vulcanize the chloroprene serves.

In order to achieve the properties required for practical use, such as high elasticity / high strength and stability, chloroprene rubber is generally mixed with additives such as vulcanizing agents, vulcanizing auxiliaries, anti-aging and anti-fatigue agents, fillers and plasticizers, molded in a mold and then used for the practical application vulcanized.

Becomes the process stage of molding and vulcanizing carried out in a metal form with chloroprene and the usual rubber chemicals and additives, so the additives contained in it can come to the surface and contaminate the metal mold. Even after removal of the vulcanized material, the stains stick to the metal mold. With repeated use of the metal mold the impurities on the mold multiply, which in turn cause defects on the surface of the vulcanized

Rubber products, such as a reduction in gloss and a roughening of the surface.

To avoid damage to the surface of the vulcanized Rubber products is a common cleanup 35

the mold is necessary to remove the stains, which inevitably reduces the efficiency of the process. A measure

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would take to solve the problem of metal mold contamination is described in JP-OS 37118 / 74-. This publication discloses a chloroprene rubber with improved properties regarding the metal mold impurities by polymerization of chloroprene with a degree of polymerization of at least $ 60 in the presence of certain amounts of Resin soaps, an alkali metal salt of a higher saturated or unsaturated fatty acid and a sodium salt of a condensation product of formaldehyde and naphthalenesulfonic acid.

In contrast to the prior art described, the process according to the invention provides a chloroprene rubber available that has a very low tendency to contaminate metal molds.

The invention thus relates to the subject matter characterized in the claims.

The term "lower alkyl" preferably means one Alkyl radical with 1 to 8 carbon atoms.

Meanwhile, a method for emulsion polymerizing chloroprene has been described in Japanese Patent Laid-Open No. 4-031 / 78 in which Styrene sulfonic acid or its derivative is used together with an emulsifier such as resin acid derivatives. According to However, styrenesulfonic acid and its derivatives are monomers and do not polymerize Compounds with which the improved effect regarding

the metal mold contamination, as it is according to the invention Procedure obtained cannot be expected.

As resin acid derivatives for the process according to the invention

can generally be used such as are generally used in the polymerization of chloroprene.

Ι den, for example undenatured rosin, disproportionated Rosin, hydrogenated rosin and their alkali irallual / .r ·; wir vcu st oluuul prwoihnt, 1 i «(j {Hi re amount at 0.5 to 5 percent by weight, preferably 1.0 to 3.0 percent by weight, based on the amount of chloroprene or the mixture of chloroprene with a monomer suitable for copolymerization with chloroprene. The amount lies below 0.5 percent by weight, the emulsion becomes less stable, if the amount is above 5 percent by weight, contamination of the metal mold can occur more easily.

Examples of the polystyrenesulphonic acids used according to the invention and their derivatives are poly-p-styrenesulphonic acid and its sodium, potassium and quaternary ammonium salts, poly-ot-methyl-p-styrenesulphonic acid sodium salt and poly-o-chloro-p-styrenesulphonic acid with an average polymerization degree of 10 to 20 000, preferably _(from 50 to 1000, wherein the amount is from 0.1 percent to 10 wt J, preferably at bit 1. 5 percent by weight based s j

ί on the amount of chloroprene or the mixture of chloroprene ' with the monomer suitable for copolymerization with chloroprene. If the amount is below 0.1 percent by weight,; this is the sought-after prevention of metal mold contamination! inclinations lower; however, amounts above 10 Ge! Weight percent should be avoided, since the po- (

polymerized chloroprene latices are too viscous. '

Depending on the circumstances, more highly saturated or unsaturated fatty acids, such as stearic acid or oleic acid, can also be used the rubber aggregates mentioned above can be used.

According to the invention, the polymerization can be carried out according to the customary Emulsion polymerization processes are carried out, x ^ obei however, the abovementioned proportions must be adhered to. The chloroprene can be used alone or

If necessary in a mixture up to 50 percent by weight of a monomer are used that is suitable for copolymerization with chloroprene, such as 1-chlorobutadiene, 2,3-dichlorobutadiene, Butadiene, 2-cyanobutadiene, styrene, acrylonitrile, alkyl methacrylate and alkyl acrylate.

Known modifiers, such as alkyl mercaptan and alkyl xanthogen disulfide be used. Examples of free radical initiators are potassium persulfate and alkyl hydroperoxide.

The polymerization should take place at temperatures from 0 to 100 C, preferably carried out at 5 to 60 ° C., the Reaction in the presence of the specified amounts of the above-mentioned compounds should be continued until a at least 60 percent conversion has taken place; the polymerization is then stopped by adding a conventional polymerization inhibitor, such as tert-butylcatechol or phenothiazine,

completed.
20th

After the polymerization reaction has ended, unreacted monomers, for example by a treatment reduced pressure and high temperature. The so formed polychloroprene latex is then cooled, coagulated, washed with water and dried to obtain the solid chloroprene rubber.

The following examples illustrate the invention. Parts are by weight unless otherwise stated.

example 1

In a 10 liter autoclave equipped with a stirrer chloroprene, which contains 2,3-dichloro-1,3-butadiene,

and the compounds listed in Table 1 below

fertilize fed. The polymerization is carried out under nitrogen at 40 C with continuous addition of 0.5 percent

aqueous solution of potassium persulfate carried out. After 70 percent Implementation of the polymerization reaction is carried out by adding an emulsion of 0.01 part each of tort .-. But.y.1 catechol and phenothiazine terminated. 'Unreacted monomers have been removed by flash distillation.

The latex formed is treated with a 10 percent solution of Brought acetic acid in water to a pH of 5.8 and the polymer via a. Freeze roller 'separated and then washed with water and dried to obtain solid chloroprene rubber.

Table 1

Polymer
No. I. II III 0 IV r V VI V ₁ II VIII Chloroprene 95 95 95 1 90 95 95 95 95 Styrene - - - 10 - - - - 2,3-dichloro
1,3-butadiene 5 5 5 - 5 5 5 5 Disproportionate
Resin acid te
2. 0 2.0 2. 25th 2. 0 2.0 2.0 2.0 2.0 Pply-p-styrene-
sulf on acid—. ■
Sodium saltζ • - - 0. 0. 5 0.5 0.5 1.0 5.0 Sodium styrene
sulfonate - 1.0 - 4th - - - - - Oleic acid - - - - 1.0 2.0 - - Dodecyl-
mercaptan 0. 25 0.25 0. 0. 25th 0.25 0.25 0.25 0.25 water LOO 100 100 100 100 100 100 100 sodium
hydroxide 0. 4 0.4 0. 0. 4th 0.4 0.4 0.4 0.4

* ■ Degree of polymerisation 1000

The polymers No. I and No. II are comparative examples for .Chloroprenk Rubbers in which no polystyrene sulfonate sodium salt was used. Table 2 below shows the values for the Mooney viscosity MLy, j, (at 100 ° C.) of the chloroprene rubber examples formed.

- I. II III Tabel 2 VI VII VIII 10 Polymeri
sat no. 64. 60 66 IV V 65 65 64 ^ 1 + 4
(at 100 ⁰ C) 65 67

Each of the under the polymer no. chloroprene-listed examples is mixed on a roll of 25.4 cm diameter at 5O ⁰ C with the following substances;

mixed substances Amount (in parts) rubber 100 Stearic acid 0.5 y MgO 4- y Soot (SRF) 40 '; Plasticizer oil 10 I. ZnO 5 2-mercaptoimidazoline 1

The products obtained are each continuously vulcanized 100 times in a different metal mold. Vulcanization takes place at 220 ° C. for 10 minutes. In Table 3 below is the contamination of the metal molds listed after 100 times vulcanization:

Table 3

Polymers
No. I. II III IV V VI VII VIII Liability of
'mixed in
Substances * 5 4-5 3-4 2-3 2 1-2 0-1 0-1

pronounced adhesion to the whole surface noticeable adhesion to the whole surface medium adhesion to the whole surface weak adhesion
almost no liability
no liability.

Of the polymers No. I and No. II prepared as comparative experiments, a significant amount of the admixed polymers adhered Substances on the metal mold, so that it is clearly contaminated with stains. Like the previous ones Results show, however, causes the addition of polystyrene sulfonic acid sodium salt a significant reduction in adhesion. Particularly noteworthy are the polymers Hr. VII and VIII, in which almost no adhesion can be noticed and the metal molds without cleaning treatment for further attempts can be used.

Example 2

There are polymers of chloroprene monomers with others Prepared substances as listed in Table 4. After performing the polymerization, isolation and Drying, the solid chloroprinc rubber is obtained in the same rolling mill as in Example 1.

Tabel

■ polymer IX X XE XII XIII XIV XV Chloroprene 100 100 100 100 100 100 100 Potassium salt of
disproportio
nated resin
acid 3.0 3.0 3.0 5.0 6.0 • 3.0 3.0 sodium salt -
the poly- «s £ -
mettiyl-p-styro:
sulfonic acid mi '
the polymer
degree of satiation - - 1.0
(n-10) 1.0
(n-50) 1.0
(n-50) 1.0
(n-50) 1.0
(n-100) 1.0
(n-100) ϊί atrium salt
the <£ -Methyl-
p-styrene sulfone
acid 1.0 - - - - ■ - - Dodecyl ^.
itiercaptan 0.21 0.21 0.21 0.21 0; 21 - 0.21 0.21 '* Water- 100 100 100 100 100 ■ 100 100 ^f · sodium
hydroxide 0.25 ' 0.25 0.25 0.25 • 0.25 .0.25 0.25

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For comparison, a chloroprene rubber without the sodium salt of poly-oC-methyl-p-styrenesulfonic acid was produced as polymer no. IX and a chloroprene was chewed as polymer XIII, in which a larger amount of the potassium salt of the disproportionated resin acid was added, which was beyond the claimed Range. From the following Table 5, the values for the Mooney viscosity ML ₁₊ ^ reproduced the formed ChIoroprenkautschuk examples (at 10O ⁰ C).

Table 5

Polyme risat
No. IX X XI XII XIII XIV XV ML _{1 + 4} (100 ⁰ C) 54 53 56 54 50 53 52

Next, the chloroprene rubbers produced under the polymer numbers given above were added the substances listed in Example 1 mixed and as in Example 1 each 100 times

vulcanized with the compounds. Then to'die 100 times vulcanization became the contamination of the metal molds as in Example 1, determined visually. The values are summarized in Table 6 below.

Table 6

Polymer
'No. IX X XI XII XIII XIV XV Attitude of
mixed in
Substances 5 2-3 0-1 2-3 4-5 0-1 0-1

V / io show the experiments listed above are the compared to chloroprene rubbers produced according to the invention prior art chloroprene rubbers

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remarkably more effective in preventing metal mold contamination.,

Claims (6)

VOSSIUS · VOSSIUS · TAUCHNER HEUNEMANN · RAUH PATENTANWÄLTE SIEBERTSTR. 4, BUOO MÖNCHEN 8O TEL- (Ο89) 47 4O 76 u.Z .: S 476 (DV / ko) June 16, 1983 Case: 8168 TOYO SODA MANUFACTURING CO., LTD. Shimanyo-shi, Japan "Process for the production of chloroprene rubber" 'claims 1. A process for the production of chloroprene rubber, characterized in ^that chloroprene or a mixture of chloroprene with a suitable for the copolymerisation with chloroprene monomer in an amount of up to 50 weight percent, based on chloroprene, in an alkaline aqueous emulsion in the presence of 0, 5 to 5 percent by weight of a resin acid derivative and 0.1 to 10 percent by weight of polystyrene sulfonic acid or its derivative of the general formula I. I I 11 -j — χ SO ₃ Y in which E is a hydrogen atom or a lower alkyl radical, X is hydrogen, lower alkyl Halogen atom or a hydroxyl group and Y a hydrogen, potassium or sodium atom or a quaternary ammonium group and η is an integer from 10 to 20,000, polymerized. 2. The method according to claim 1, characterized in that the resin acid derivative in an amount of 1.0 to 3.0 percent by weight is present. 3- The method according to claim 1, characterized in that the polystyrene sulfonic acid or its derivative in one Amount of 1.0 to 5? 0 percent by weight is present. 15th 4-, The method according to claim 1, characterized in that the mixture of chloroprene with the monomer additionally contains a molecular weight modifier and a radical initiator.
20th 5. The method according to claim 1, characterized in that the added to the chloroprene monomer 1-chlorobutadiene, 2,3-dichlorobutadiene, butadiene, 2-cyanobutadiene, styrene, Is acrylonitrile, alkyl methacrylate or alkyl acrylate. 25th 6. The method according to claim 1, characterized in that the polystyrene sulfonic acid or its derivative poly-pstyrene sulfonic acid or its sodium, potassium or quaternary ammonium salts, poly ex. methyl-p-styrenesulphonic acid sodium salt or poly-o-chloro-p-styrenesulphonic acid with an average degree of polymerization of 50 to 1000.