DE2042081B2 - Use of α-sulfocarboxylic acid salts as release agents for natural and synthetic elastomers - Google Patents

Description

The invention relates to the use of »sulfocarboxylic acid salts as release agents for natural ones and synthetic elastomers.

For example, in the manufacture of rubber goods made from natural and synthetic rubber Release agent needed once after manufacture the unvulcanized rubber mixture prevents the skins or blanks from sticking together until further processing and, on the other hand, prevents the Prevent unvulcanized rubber mixture in the vulcanization mold and thus enable the vulcanizate to be easily removed from the mold.

A large number of different products have already become known as release agents for elastomers powder and liquid release agents. The best-known representatives of powder release agents are z. B. talc or zinc stearate to name. The main disadvantages of these powdering agents are their generation of dust in the factory and the sometimes poor weldability of the with Talc or corn powder treated blanks during vulcanization.

One tries to counter the disadvantageous dust development of the powder compositions by the Powdering agent is slurried in an aqueous phase, through which the unvulcanized rubber compound sheets are then drawn.

Another way of addressing the disadvantages mentioned to counter, consists in doing without powdering agents and using liquid release agents, under those based on fatty acids because of their economy and the possibility of being in aqueous solution to be used, still have the greatest importance. In many cases where release agents are used Fatty acid base kfine develop sufficient separation effect, z. B, as a mold infiltration agent, are proposed Mainly silicone oils and fluorinated hydrocarbons are used as release agents. Besides the higher prices However, these products have the disadvantage that the release agent fractions transferred to the vulcanizate Adhesion of a subsequently applied finish or a lacquer adversely affect and also the Prevent the vulcanizate from sticking to form a composite article.

ίο The present invention is therefore the task based on finding release agents which have a very good release effect but do not have the disadvantages outlined above.

This problem is solved by disalting from Ä-sulfocarboxylic acids with a chain length of 8 to 26 Carbon atoms and alkali metals, magnesium, ammonium, short-chain aliphatic amines or short-chain aliphatic alkanolamines as release agents for natural and synthetic elastomers used

The following a-sulfocarboxylic acids, for example, may be mentioned as anion components of the disalts used according to the invention: a-sulfocaprylic acid, a-sulfocapric acid, Λ-sulfolauric acid, ct-sulfo-hydrogenated-coconut fatty acid, «-Sulfomyristic acid, a-sulfopalmitic acid, Ä-sulfostearic acid,

(X-sulfo-hydrogenated-peanutoleic acid, «-Sulfo-hydrogenated-rapeseed oil fatty acid, Λ-sulfo-hydrogenated-palm kernel fatty acid, a-SuIfo-hydrogenated-soy-fatty acid, «-Sulfo-hydrogenated-tallow-fatty acid, a-SuIfo-hydrogenated-fish-

and transfatty acids, Λ-sulfobehenic acid.

Furthermore, α-sulfocarboxylic acids come into question, the by sulfonation of synthetic fatty acids, for example by paraffin oxidation, by carboxylation of organometallic compounds such as. B. organoaluminum compounds, by oxidizing cleavage of olefinic compounds or by other oxidation reactions, for example ozonization of olefins and subsequent oxidizing Splitting of the ozonides with oxygen, or otherwise produced.

The production of the α-sulfocarboxylic acids can according to known processes, for example by complete or partial sulfonation of the corresponding fatty acids by means of sulfur trioxide. The further processing to uen disalts then takes place Neutralization of the obtained Ä-sulfocarboxylic acids with the appropriate base, with the possibility of The preparation of mixed salts consists in first undertaking a partial neutralization with a base and the neutralization is completed with another base. To be used according to the invention Disalts can also contain considerable amounts of ester salts of α-sulfocarboxylic acids.

The alkali metals sodium are used as the cation component of the disalts used according to the invention. Potassium, lithium and magnesium. Ammonium, hi short-chain aliphatic amines with 1-4 carbon atoms v / ie methyl, ethyl, propyl, isopropyl and Butylamine and short-chain aliphatic alkanolamines such as mono-, di- and triethanolamine in Fraee. One

The disalts of the alkali metals sodium and potassium are of particular importance.

As both technically and economically important are the di-sodium and. Di-potassium salts of α-sulfocarboxylic acids with a Address chain length of 12 to 18 carbon atoms. They primarily include products that derived from naturally occurring fats and oils.

According to the invention as a molding or Layer release agents for natural or synthetic elastomers to be used disalts of -sulfocarboxylic acids are expediently in aqueous solution and a concentration of 0.1 to 10 wt .-%, preferably 0.2 to 2% by weight is used

In order to achieve certain effects, it is possible, in a known manner, to improve the water-soluble polymers add the film formation and to increase the viscosity of the solutions. E.g. Carboxymethyl cellulose, hydroxyethyl cellulose and methyl chloride. The products are commonly used individually in technical purity, but mixtures of the compounds with one another are also possible as well as with emulsions of silicone oils and fluorocarbons.

In order to achieve a good separating effect between unvulcanized rubber sheets, these are expedient coated with the solution of the release agent, sprayed or immersed in the solution The molds made of steel, aluminum or chrome-plated steel are used as mold coating agents brushed or sprayed with the aqueous solutions and the water evaporates

Even if usually Watser as a solvent is preferable for the release agents to be used according to the invention, on the other hand it is preferable for certain Application forms, e.g. B. in spray cans, also possible, additional organic solvents such as methylene chloride or lower alcohols, alone or as a mixture.

The following examples are intended to explain the subject matter of the present invention in more detail without implying it to restrict.

Examples

1. In these experiments, the separating effect of the -sulfocarboxylic acid salts to be used according to the invention was determined and various other release agents on cast polyurethane elastomers. There were the following polyurethane products are used:

Mixture a)
Soft polyester polyurethane

100 g linear polyester (made from adipic acid and ethylene glycol, OH number about 55, average Molecular weight 2000)

18 g of naphthylene-1,5-diisocyanate

2.3 g of a mixture of 80% butanediol-1,4 and 20% Trimethyl oil propane

Mixture b)
Hard polyester polyurethane

100 g linear polyester (made from adipic acid and ethylene glycol, OH number about 55, average Molecular weight 2000)

30 g of naphthylene diisocyanate
7 g of 1,4-butanediol

Mixture c)
Polyether polyurethane

100 g reaction product of polytetramethylene ether glycol with excess toluene diisocyanate
ίο 12 pounds of 4,4-methylene-bis-2-chloroaniline

From the aforementioned raw materials, mixtures were prepared in the usual way at an elevated temperature according to Voi script of the raw material suppliers and poured into steel molds that had been thoroughly cleaned beforehand and, after cleaning, coated twice with the solutions listed in the table below. Before filling, the molds were ^{preheated to 100 to 110 °} C. The temperature in the polyurethane compositions was approx. 130 ^{° C. for mixtures a) and b), and 110 °} C. at the time of filling for mixture c). The polyurethane compositions were cured for mixture a) and for mixture c) for 3 hours at 110 ^° C., whereas mixture b) was ^{cured at 110 ° C. for 24 hours.} Subsequently, demoulding and the force required for demolding was determined subjectively. The results of the tests are shown in the table below.

The products listed below were used as mold release agents in the form of a 0.5%, aqueous solution used

Release agent A) Alkali salt one

Fatty acid derivatives,

B) ammonium alkyl phosphate,

C) sodium alkyl sulfate,

D) sodium lauryl ether sulfate,

E) ammonium lauryl acetate; r-sulfate,
F) triethanolamine lauryl ether

sulfate,

G) triethanolamine lauryl sulfate,
H) xylene sulfonate,
I) cumene sulfonate,
K) Turkish red oil, degree of sulphonation

approx. 50%,
L) Turkish red oil, degree of sulphonation

approx. 65%,

M) sec. A / kansulfonat, commercial product
-, o N) alkylbenzenesulfonate,

O) fatty alcohol polyglycol ether,
P) ethoxylated fatty amine,
Q) cetyl trimethyl ammonium chloride,
R) coconut fatty acid poly-diethanolamide,
S) Na-Ä-suIfo-hydrogenated-palm-kernel-

fatty acid methyl ester salt
T) Na - «- sulfo-hydr. Tallow fatty acid methyl

ester salt,

U) disodium salt of a-sulfo-hydr. Parish kernel fatty acid,

V) disodium salt of Λ-sulfo-hydr. Tallow fatty acid,
W) disodium salt of the Λ-suIfo-palmitin-

acid,
h5 X) disodium salt of Λ-sulfo-hydr. Ko-

cosfatty acid,
Y) disodium salt of a-sulfo-hydr. F.rd-

nut oil fatty acids.

20 42 081 5 A) 5 ß) 10 Well fjutadiene rubber mixture next Mixture b) 6th Disodium salt of «-sulfo-hydr. Röb- Well he composition for the investigation c'.er Well acid mixture obtained by Z) oil fatty acid, bad ineffective used. Well Direct sulfonation of the Cio-ir main Disodium salt of a-sulfo-beehic acid bad bad Fatty acids from paraffin oxidation, τ) re, Demoulding search for cast polyurethanes bad bad Di-triethanolamine salt of a-sulfo- Di-magnesium salt of a-sulfo-myri- Release agent mixture a) bad bad stearic acid, B) stinic acid, A. bad schiesch Na - «- sulfo-hydr. Palm kernel fatty acid Di-isopropylamine salt of an et-sulfonic acid B. satisfactory bad methylsler salt with a content of Ω) regemssches, obtained by ozone C. satisfactory satisfactory Disalt of 5%, tion of a cis-ie-a-olefin from the D. bad satisfactory Disodium salt of a-sulfo-hydr. Palm Paraffin cracking and subsequent E. very moderate nuclear fatty acid containing Direct sulfonation, F. satisfactory Well - «- siilfo-hydr. Palm kernel fatty acid DJ ammonium salt of a «-Sulfocar- G bad satisfactory - good methyl ester salt of 10%. Ψ) Table I. H bad I. bad bad K bad bad Mixture c) L. bad bad Well M. bad bad Well N bad bad O very good bad P. very good very good Q very good very good R. Good Excellent very good S. Good Excellent very good Well T very good very good Well U Well very good V Good Excellent Well W. very good Good Excellent satisfactory - good X Good Excellent very good Y Good Excellent very good Z Good Excellent Good Excellent β Good Excellent very good ε In a further attempt a "self-liable very good τ : «Styrene - 65 loo weight parts π 1.5 parts by weight Ω 5 parts by weight very good φ 1 part by weight very good λ very good Good Excellent very good very good very good very good very good very good Well Good Excellent very good Styrene-butadiene rubberSBR 1500 Stearic acid zinc oxide Phenyl-o-naphthylamine

30 parts by weight of precipitated silica

2 parts by weight of aromatic oil

2 parts by weight of black lead

1.8 parts by weight of secondary amine

6 parts by weight of a 1: 1 mixture of precipitated silica

and resorcinol

1.6 parts by weight of hexamethylenetetramine

1 part by weight of N-cyclohexyl-1-benzthiazylsulfenamide

1 part by weight of di-o-tolylguanidine

1.8 parts by weight of sulfur

This mixture is specially formulated so that it can be applied to metal surfaces without the use of rubber-metal binders adheres and vulcanized at 153 "C for 10 minutes in a conventional press vulcanization. Before vulcanization, the steel vulcanization mold was thoroughly cleaned and given a 0.5% strength Solution of release agent already listed in Example 1 coated once. In the form so prepared were as long as sheets of the above mixture, without re-treating the mold with release agents, produced until significant demolding difficulties arose. The number of pressings is thus a measure of the productivity and effectiveness of the release agents used. The results are as follows Table II can be found.

Table II number Tiennmitlel of the pressings 2 A. 1 D. 1 E. 1 F. 1 G I. M. 2 I. 1 M. 1 O 2 P. 1 R. 1 S. 1 T 6th U 8th V 6th W. 4th X 6th Y 6th Z 6th I. 5 π 4th Ω 4th Ψ 8th λ 4th β 8th ε

3. silicone rubber
(commercially available, weakly vulcanizing type)

Newer types of silicone rubber, which, in contrast to the previously common types, are after vulcanization in the The press is not subjected to additional post-curing in circulating air in order to achieve good mechanical properties must be, adhere quite strongly to the walls of the vulcanization mold and result consequently easy demolding difficulties after vulcanization. The following were used for the experiments Silicone rubber compounds used.

a) 100 parts by weight of rubber-like methylpolysiloxane

(commercially available high-molecular type)
1.2 parts by weight of dicumyl peroxide

b) 100 parts by weight of rubber-like methylpolysiloxane

(commercially available high-molecular type)
1.2 parts by weight of dicumyl peroxide

The vulcanization was carried out at 155 "C for 15 minutes.

As a mold release agent, the inventive V) disodium salt of Λ-sulfo-hydr. Tallow fatty acid (s. Example 1) and a commercially available silicone release agent used for comparison. It was found that a single coating with a 0.5% solution of the Release agent V) according to the invention (see Example 1) was sufficient, while the silicone release agent in much higher layer thickness than scr. :: usual

r> had to be applied.

4. For the following experiment a very sticky, soft natural rubber mixture became the following Composition used.

100 parts by weight of natural rubber NR-RSS I
^{! 0} 10 parts by weight of zinc oxide
2 parts by weight of stearic acid

1 part by weight of phenyl-3-naphthylamine

2 parts by weight of spruce tar
25 parts by weight EPC carbon black

033 parts by weight of zinc dimethyl dithiocarbamate
0.58 parts by weight dibenzothiazyl disulfide
2.75 parts by weight of sulfur

First, mixing plates according to the above recipe were immersed in 0.5% solutions of the various release agents according to the list in Example 1. After the water had evaporated, two plates treated in this way were placed on top of one another and loaded with weights so that a pressure of approx. 200 g / cm ² resulted. After 24 hours, a check was carried out to determine whether the two plates could easily be separated. Thereafter, the two plates were stacked again and pressed in a vulcanizing press for 10 minutes at 153 ⁰ C. The vulcanizate was then examined to determine whether the two plates were flawlessly welded to one another during the vulcanization process, ie the separating effect of the applied separating agent was canceled again. The results of the experiment are given in Table HI below.

Table HI Layer separation Welding Layer release agent moderate very good D. moderate very good E. moderate very good F. moderate very good G moderate very good H moderate very good I. moderate very good M.

continuation

üigentrennmiltel layer separation

O R

S T

and many more

moderately moderate

moderate - good moderate - good very good very good very good very good good - very good very good

Welding "

very good very good very good very good very good very good very good very good very good very good

When the disalts of Λ-sulfocarboxylic acids of one chain length are used according to the invention of 8-26 carbon atoms as a release agent for elastomers is that can achieve both an excellent layer and shape separation without the later gluing of the Vulcanizate to a composite article or the subsequent application of a Painting is adversely affected.

Claims (5)

Patent claims: 1. Use of disalts from -sulfocarboxylic acids with a chain length of 8-26 carbon atoms and alkali metals, magnesium, ammonium, short-chain aliphatic amines or short-chain aliphatic alkanolamines !! as a release agent for natural and synthetic elastomers. 2. Use of di-sodium or di-potassium salts of α-sulfocarboxylic acids according to Claim 1 as a release agent for natural and synthetic elastomers. 3. Use of di-sodium or di-potassium salts of Ä-sulfocarboxylic acids with a chain length of 12-18 carbon atoms according to the Claims 1 and 2 as a release agent for natural and synthetic elastomers. 4. Use of disalts of α-sulfocarboxylic acids according to Claims 1 to 3 in 0.1-10% strength _s, preferably 0.2-2% strength aqueous solution, as a release agent for natural and synthetic elastomers. 5. Use of disalts of cc-sulfocarboxylic acids according to claims 1 to 4 with a Content of ester salts of α-smfocarboxylic acids as Release agent for natural and synthetic elastomers.