DE908916C - Process for the production of sponge rubber counterstay ends from synthetic rubber - Google Patents

Description

(WiGBl. P. 175)

ISSUED APRIL 12, 1954

G 7752 IVc j 39b

The invention relates to the manufacture of articles made of sponge rubber and synthetic rubber Rubber, such as B. butadiene-styrene copolymers.

The invention makes it possible to produce vulcanized synthetic sponge rubber which has the Properties of vulcanized sponge rubber made from natural rubber milk achieved. The sponge rubber articles produced according to the invention consist of one essential part of butadiene-styrene copolymer and contain to influence the physical Properties in addition to certain other types of synthetic rubber.

More precisely, the physical properties a sponge rubber article made of butadiene-styrene copolymer influenced by Addition of 10 to 50% polybutadiene, based on the total amount of rubber.

Experience has shown that sponge rubber items are made from certain synthetic rubbers.

While sponge rubber articles made from 2-chlorobutadiene polymer have pretty good physical properties Have properties that are lacking from butadiene-styrene copolymer a certain handle that is known from natural rubber sponge rubber objects. This grip depends on

the physical properties of the object, especially its elasticity. Sponge rubber items from butadiene-styrene mixed polymer have at elevated temperatures satisfactory properties, but lose their elasticity with decreasing temperature. they are then dead and will not return to their previous shape after being squeezed.

Because of this special physical characteristic; ίο could get sponge rubber objects off Butadiene-styrene copolymers have not yet caught on, precisely because they are made of sponge rubber should maintain the required properties within a wide temperature range. A process used in the manufacture of sponge rubber articles from butadiene-styrene mixed polymer To avoid occurring difficulties, consists in the dispersion of the butadiene-styrene copolymer to mix in certain proportions with natural rubber milk like it The subject of patent 852 902 is.

However, it is very desirable to use sponge rubber articles made from pure butadiene-styrene copolymer to be able to manufacture. It has been found that by adding a dispersion of a specific synthetic Rubber to the butadiene-styrene copolymer dispersion, the properties of the produced therefrom Vulcanized sponge rubber can affect articles so extensively that they are really usable Item to be received. The addition of polybutadiene dispersion changes in particular exactly certain amounts the properties in a satisfactory manner, z. B. the elasticity of the Items noticeable compared to those made from pure butadiene-styrene copolymer dispersion were manufactured.

By adding 10 to 50% polybutadiene dispersion to a butadiene-styrene copolymer dispersion a rubber milk is obtained which, after mixing, foaming and vulcanization, gives a Provides articles whose elasticity increases in proportion to the amount of polybutadiene dispersion used. Any of the commercially available butadiene-styrene copolymer dispersions is suitable for use in the manufacturing process described below and provides, provided that it is used in the following requirements described, satisfactory results.

The polymerization substances and conditions of the polybutadiene dispersion are not decisive. The main condition is the alkaline nature of the dispersion with a pn value in the range of preferably 10.5. It is desirable, but not absolutely necessary, for the dispersion to have a high content of solids, since the dispersions mixed with one another have to contain ^{50 0} Z _{0 and more solids at the end.}

For example, a butadiene-styrene copolymer dispersion used with a share of 55 ° / ₀ solids, the polybutadiene has at least 45 ⁰ ₀ Z contain solid substances, if the mixture is to consist of identical parts.

If, however, for example, a mixture of 90 ° / ₀ used butadiene-styrene copolymer dispersion and 10% of polybutadiene, the polybutadiene may contain much less than 45 ° / ₀ solids.

In general, it is desirable that the polybutadiene dispersion has a relatively high content of solids; as long as the finally, the mass obtained after mixing and foaming contains 50% or more solids, this is not absolutely necessary.

The butadiene-styrene content in the styrene-butadiene copolymer dispersion can be changed in common use industrially ratios for styrene vary between 5 and 50 ° / _0, and each dispersion prepared within these limits is suitable in a wide range.

The elasticity data given below change with the percentage of styrene and Butadiene-styrene copolymer.

In all cases, the elasticity of the mixture was compared to that of the pure butadiene-styrene copolymer improved. The following substances (in Parts by weight):

j variable, _go Aqueous dispersion of butadiene-like

Styrene copolymer > below

Polybutadiene

J given

Basic approach (see below) 57

35 ° / _o sodium potassium castor oil soap

solution 8 to 12

Glass fibers (3.175mm long) 9

Aminoacetic acid 25

Sodium fluorotitanate

(40% slurry) 15 to 25

In the above mixture, the glass fiber content can be changed or omitted entirely.

Instead of aminoacetic acid, any buffer can be used that adjusts the pH of the mixture keeps the required limits.

Instead of sodium fluorotitanate, other fluorotitanates (subject of patent 854259) or Fluorozirconates (subject of patent 852 902) can be used, as well as sodium fluorosilicate or a other gelling agent, in amounts as are known to the person skilled in the art.

Vaseline or casein solution can be added to regulate the density and stability of the foam all of these amendments are known.

The stated composition of the basic approach can also be varied; she poses only represents the basic approach used for the experiments.

Basic approach

Zinc oxide 600 parts by weight

Titania 120

Sulfur 300 -

Zinc-mercapto-benzothiazole .... 150

Piperidine pentamethylene

dithiocarbamate go parts by weight

Zinc diethyl dithiocarbamate .. 6o symmetry. Di-betanaphthyl

p-phenylene-diamine 90

Ammoniacal casein

solution (10%) _; 525

10 ° / _o solution of polymerized alkyl aryl sodium

sulfonate 358

In all cases the mass was foamed until the foam had reached a sufficient height in a mold is filled, gelled and vulcanized for 30 minutes at 100 ° in open steam, after which the objects dried and examined. This resulted in the following values:

composition

Butadiene styrene
Mixed polymer Polybutadiene elasticity 0 /
/ 0 % 100 15.O 90 IO l6.2 80 20th 17.7 70 30th 19.7 60 40 23.0 50 SO 27.0

The dimensions of the test pieces were approximately 14 × 14 × 3.6 cm with an essentially constant Density.

All elasticity values given are results of the Bashore elasticity meter and represent the mean value of at least four measurements, all four measurements being taken at 28 °. In in all cases the specimens were compressed to a thickness of 1.8 cm starting from 3.6 cm when unloaded. It can be seen from the values that the elasticity of the test pieces increases markedly when the percentage of Polybutadiene dispersion in the finished mixture is increased. Even with an addition of only 10 ° / " Polybutadiene dispersion increases the elasticity compared to that of the test piece made of 100% butadiene-styrene considerable.

The following values illustrate the increase in elasticity over a wide temperature range, where the tests were carried out as indicated above and with the same test pieces.

Composition (experiment at Polybutadiene
Vo 15 ") Butadiene styrene
Mixed polymer
/ 0 _ elasticity IOO IO 0.5 C) O 20th i, 5 80 30th 3.5 70 40 5.8 60 SO 6.9 50 10.0

Composition (attempt at 82 ⁰ )

Butadiene styrene
Mixed polymer Polybutadiene elasticity / 0 Vo 100 38.4 90 IO 38.6 80 20th 38.8 70 30th 41.0 60 40 43.0 50 SO 48.4

It can be seen from these test results that the elasticity over a wide temperature range is noticeably improved by adding polybutadiene dispersion and that the optimum Elasticity is achieved if a dispersion of butadiene-styrene copolymer is 30 to 50% Polybutadiene can be added.

An addition of 50 ° / ₀ polybutadiene to the butadiene-styrene copolymer dispersion seems to be the biggest ever angängige value. The tensile strength decreases in proportion to the increase in elasticity of the rubber mixture. For this reason, it is necessary to use a composition in which the elasticity becomes the highest value compatible with the other physical properties of the object. In other words, the addition of polybutadiene must be limited so that both the elasticity and the other physical properties of the resulting sponge rubber are equally taken into account and weighed against one another. It has been found that the tensile strength decreases proportionally to the increase in the percentage of polybutadiene, while the elongation decreases only slightly, as does the modulus of 300% elongation. With the exception of the elasticity, all the physical properties of the sponge rubber are therefore impaired, so that an optimum value must be selected at which satisfactory physical properties can still be achieved despite high elasticity. For this reason, a mixture of 50 ° / ₀ consider butadiene-styrene copolymer dispersion and 50% of polybutadiene in relation to the Polybutadienzusatz as the outermost boundary. The test results of the four different compositions are given below:

Butadiene Poly Shore Tear Deh module Styrene
Mixed butadiene test strength tion kg / cm ² polymer Vo A. kg / cm ² Vo at 300 ° / " 100 _ 41 52.25 475 25.1 80 ■ 20th 39 35.9 530 12.65 60 40 39 25.0 422 14.4 50 50 '4 ¹ 24.6 400 16.0

All test panels were produced and vulcanized under the same conditions.

From the figures it can be seen that with the greatest elasticity, namely with a mixture of

gk-khen parts of polybutadiene and butadiene-styrene copolymer the tensile strength for cushioning material is still high enough, while the elongation has not yet changed noticeably, although it has been reduced a little, as is the module at 300% elongation. In all cases the Shore Test A hardness is essentially constant. In the Above tests were all sample pieces according to the regulations and methods of American Material testing company examined for the elongation test of vulcanized rubber.

In all cases, a dispersion of butadiene-styrene copolymer forms the main component of the mixture due to the fact that even with a mixture of equal parts, the solids content of the butadiene-styrene dispersion is on average over 50%, while the polybutadiene dispersion is in the generally less than 50%
Contains substances.

fixed

Claims (2)

PATENT CLAIMS: 1. Process for the manufacture of articles from vulcanized sponge rubber using a dispersion of butadiene-styrene copolymers as the main principle Rubber component, characterized by the addition of 10 to 5o% polybutadiene dispersion, preferably 50% based on the total amount of those used in the mixing process Rubber dispersion. 2. The method according to claim 1, characterized in that that the mixture of the rubber dispersion is alkaline and in the production of the foam a content of at least 50% has solid substances. 5904 4.54