DE818572C - Process for the treatment of latex with aqueous hydrogen peroxide solutions - Google Patents

Description

The rubber factories always have this wish had, from the plantations- the rubber in dry plates to be obtained in a certain degree of plaisticity, which meets the requirements of the manufacturing process for which this rubber is intended. A corresponding request was made regarding the liquid latex, which in most cases only leads to annoying end products.

Attempts have already been made to increase the viscosity of the latex by the action of oxidizing agents modify it to make it sticky !. The use of a little concentrated 6% hydrogen peroxide solution has "insufficient for only one" even if the treatment is repeated several times sticky glue led.

The plasticity was found to be made from hydrogen peroxide treated latex Rubber, in particular on the concentration of the hydrogen peroxide, on the treatment temperature and, if applicable, on the Number of consecutive handling is reluctant Hydrogen peroxide and that it fluctuates in the same sense as these factors.

The invention according to the present application

is essentially after a first embodiment, that one latex with hydrogen peroxide treated, taking the factors given above with a view to being accurate S certain endiplasticity coordinated, then the rubber of the latex according to 'well-known Procedure, e.g. B. by coagulation separates.

You can also use 6 to 75 percent by weight hydrogen peroxide solution and up to temperatures reaching around 60 °. But one works preferably at the temperature of the Surroundings.

It has now been found that with aqueous hydrogen peroxide _{solutions containing more than 6 percent by weight H 2} O ₂ , the plasticity of this rubber obtained from the latex can be arbitrarily influenced and the mechanical plasticization of this rubber can be simplified or made completely unnecessary.

ao The invention relates to a process in which the treatment is carried out at temperatures below 60 °, preferably at ambient temperature, with _{aqueous solutions containing 6 to 75 percent by weight H 2} O ₂ and optionally the rubber, e.g. B. by coagulation isolated.

According to a preferred embodiment of the invention, the hydrogen peroxide solution is added in several parts one after the other and 'cools the latex after each part has acted.

For the production of latex or rubber, the certain viscosity or plasticity properties have, one can proceed in such a way that one in the required proportions mixes ordinary latex with a latex which, under the conditions given above, with konr centered hydrogen peroxide solution treats the wound, and optionally the rubber from the so produced latex mixture isolated.

The following description gives indications as to how the method according to the invention is carried out can be.

The starting point is natural latex, which can be any stabilizer of the usual type, e.g. B. Casein, was added to avoid any coagulation. For this purpose one gives in if necessary ammoniacal medium and several times a weight of 33 per cent. hydrogen peroxide, which is equal to the weight of the dry rubber contained in this latex. For example there to 1 liter of 60% latex, d. H. a latex containing 600 g of dry rubber to several Times 600 g of 33% hydrogen peroxide solution. In each case, part of the total amount of hydrogen peroxide is added cold the foam settles, heated for about 3 hours, allowed to cool, and repeat this sequence of operations.

The table below underlines the interest that is, with higher percentage, z. B. 33% hydrogen peroxide to work and to add the hydrogen peroxide several times:

Way of working Skimmed One-time ■ Unique Encore Encore 60% latex Encore Encore on 4 times on 4 times after drying of 6 ° / ₀ sodium of 33% of 6% of 33% in warm air hydrogen hydrogen hydrogen hydrogen at 5o ° superoxide superoxide superoxide superoxide to latex to latex to latex to latex Temperature: 30 " no encore = (100%
of weight = (100%
of weight of weight = (100%
of weight of hydrogen on dry on dry on dry on dry superoxide Rubber) Rubber) Rubber) Rubber) Flowability in Barbey degrees, at 56 ⁰ , a solution of ι g dry rubber 290 ⁰ 350 ° 500 ⁰ 7OO ⁰ 18OO ⁰ in 100 ecm crystallizable more natural benzene latex Latex A Latex B

The Fließbarkedt of i8öo ° Barbey corresponds exactly the plasticity of a dry rubber after kneading on the heated plates of a mixer, with a view to producing a Benzene solution with optimal stickiness properties.

· It should be noted that in most cases rubber-based glues are used glue dissolved in benzene is preferred to liquid latex, as it comes from the plantation, namely

This is because the adhesive strength is improved by kneading the dry rubber on the rollers is a mechanical process that cannot be carried out with latex (the kneading leads to a Increasing the plasticity of the rubber).

In general there is no interest in continuing the addition of hydrogen peroxide, because the plasticity of dry rubber continues to increase, at the expense of its rubber properties, as the following table shows:

Procedure Addition of 33% Addition of 40% Addition of 45% Crystallizable 33% 33 ° / _o sodium 33% benzene hydrogen hydrogen hydrogen superoxide, superoxide, superoxide, related to related to related to Dry rubber, Dry rubber, Dry rubber, to latex B to latex C to latex D 4200 ° Temperature: 30 ° (1800 ⁰ Barbey) (1800 ⁰ Barbey) Flowability in Barbey degrees, at 56 °, a solution
of ι g dry rubber 314O ⁰ 358O ⁰ 37OO ⁰ in 100 ecm crystallizable benzene Latex C Latex D

The procedure is carried out at a precisely determined temperature, because the plasticity is changed by the temperature factor and increases with it. The temperature must therefore correspond to the degree of plasticity which one wants to achieve at the end of the procedure.

It is to be noted that one at the production sites of the latex, where the mean temperature minimum is always quite high, suitably at the temperature of the surroundings without any! Heating process can work.

The table below shows the fluctuations in flowability on, d. H. The variation in the plasticity of the rubber as a function of the treatment temperature:

Treatment temperature
in "C 20 ° 30 ° 40 ° 50 ° 6o ° Flowability
in Barbey degrees,
at 56 °,
a solution
of ig dry rubber
in too ecm
iristallizable benzene I3OO ⁰ i8oo ° 2250 ° 2450 ° 2500 °

If you have plasticization at temperature of 60 °, there is noticeable evaporation and coagulation is to be feared, if you exceed this temperature.

percentage
on dry plasticized latex
from 1800 ° Barbey
in the total dry rubber compound 0 IO 20th 30th 40 850 ° 60 70 80 90 100 Flowability in Barbey degrees,
at 56 °, a solution
of ι g dry rubber
in 100 ecm crystallizable benzene 290 °
nature
latex 400 ° 520 ° 620 ° 720 ° IO5O ⁰ I28O ⁰ I42O ⁰ 162O ⁰ 1800 ⁰

One can determine the plasticity of these different mixtures after coagulation, washing and drying measure with any plastometer.

The importance of the prior plasticization of the rubber is due to the fact that the rubber manufacturers have long wanted to have rubber supplied that was already on in a suitable manner the degree of plasticization was brought to the. Production of each category of mixtures on Best corresponds. The present procedure for

The treatment can take place in sheet metal vessels of any size and shape, preferably those made of enamel sheet. While ^one pours the hydrogen peroxide into the latex, stirring the mass; then you let them dismount.

The in suspension form, e.g. B. at 1800 ⁰ Barbey, plasticized latex can either be concentrated, mixed with ammonia and! Shipped in barrels or coagulated, washed and dried in plates, depending on the method used on the plantations. When using the method described in the present invention, the owner of the planitagen can supply dry guinea sheets of a very specific plasticity.

If you have dry rubber sheets of different Want to obtain degrees of plasticity, it is not necessary to change the conditions that are used in the manufacturing process had been used - (temperature, amount of hydrogen peroxide, etc.), but one can easily proceed as follows:

If you z. B. usually produces plasticized latex from 1800 ⁰ Barbey and wants to produce a less plasticized latex, it is advantageous ^{to mix the latex that has already been plasticized to 1800 0} Barbey with a certain amount of untreated natural latex.

The following table shows that the whole range of necessary plasticities can be produced in this way. can:

chemical plasticization of rubber now has the following advantages:

1st quality: While kneading the dry rubber sheets on cold or hot rollers, even if it is checked by means of a plastometer, it only approximates a certain plasticity The present procedure offers guarantees of regularity unknown until now and accuracy.

2. Cost price: The use of plastic

fied rubber types offers rubber manufacturers the possibility of considerable savings in electrical energy, manpower and Equipment maintenance costs. The mixing performance of a roller mixer that is no longer mechanical The kneading of the rubber will have to be much greater than that of the plasticized rubber is already in the suitable state to absorb the admixtures, whereby the equipment amortization costs of the factory decrease.

Since the energy consumption is very low, it can be used for the same production capacity Apparatus can be of a much lighter construction and is therefore less expensive to procure.

The chemical plasticization of the rubber corresponds to a depolymerization of the rubber, which is identical to that which is obtained mechanically with a roller mixer. The rubber so plasticized is vulcanized in the normal manner, and the natural or accelerated aging of the vulcanization product is excellent. The use of the z. Antioxidants currently used are particularly recommended for the rubber treated according to the method of the present application. The acetone extract of a ^{rubber plasticized to 1800 0} Barbey corresponds to that of the rubber of the same untreated rubber. As a result, there is no abnormal gumming of the rubber and it is likely that the effect of oxygen is only catalytic.

The latex plasticized in this way can be shipped like the same untreated latex.

Its modulus of elasticity is less high after vulcanization; which come out of it without adding any Articles made with plasticizers are therefore more pliable than those that are generally made with the same ordinary. Latex receives. You can have it, alone or in whatever you want Quantity ratio mixed with untreated latex, for the production of dipping, molding and Spinning objects where the characteristic of suppleness is important, and also for Use for making paints, etc.

Of course, changes can be made to the method described above in detail without departing from the scope of the invention. In particular, the reaction time can be more than three hours, because this number represents only the minimum period of time; it can be increased to 24 or even 48 hours; the only disadvantage is that the production time is extended. Beyond about 3 hours, the time factor has practically no effect on the reduction in the degree of plasticization. It should be noted that the use of cooling after the reaction of the hydrogen peroxide is complete is advantageous in that it avoids excessive foaming and loss of oxygen and latex, so that even if the reaction is carried out at ambient temperature of about 30 ⁰ in the plantation, there is an interest in it, e.g. B. to 10 or 15 ⁰ to cool. Finally, the treatment can also be carried out in a closed container.

Claims (3)

Patent claims: 1. A process for the treatment of latex with aqueous hydrogen peroxide solutions, characterized in that the treatment at temperatures below 6o °, preferably at ambient temperature, with 6 to 75 percent by weight of H ₂ O ₂ -containing aqueous solutions and optionally the rubber, z. B. by coagulation isolated. 2. The method according to claim 1, characterized in that that the hydrogen peroxide solution is added in several parts one after the other and cools the latex after exposure to each part. 3. The method according to claim 1 and 2, thereby characterized in that the latex treated with hydrogen peroxide is untreated Adding latex in the ratio required in each case to achieve a certain degree of viscosity. 1975 10.