DE1904709A1 - Prevention of frosting of coloured rubbery - vulcanisates based on polybutadiene - Google Patents

Abstract

Moulding compn. is reacted with 0.05 to 0.15, pref. 0.1 wt.% based on rubber, of a diaminodiphenylalkane or a substn. product thereof of formula: where R is H or C1-5 alkyl. Reaction is effected befor vulcanisation of the moulding compn.

Description

Method of Preventing Frosting of Rubber Bodies The invention relates to a method for preventing frosting in colored vulcanizates Butadiene-based rubber and common additives.

"Frosting" is a common term taken from English for a phenomenon which is a major problem with rubber articles. These The phenomenon is caused by an oxidation process on the surface. Usually Frosting is triggered by the action of ozone. A rubber article with a frosting appearance on the surface reminiscent of hoarfrost. The originally bare and smooth surface shows haze. On microscopic examination shows the frosting phenomenon essentially a wide variety of microcracks. The frosting problem is in Kautschuk und Gummi 1959 page 68 WT ff. Dealt with in detail.

It is used for vulcanizates of natural rubber compounds to prevent frosting known to use psp'-diamino-diphenylaethane. The following is this chemical Connection designated with DÄDM. With natural rubber, the DADX comes in a lot of ot3 - 0.6% by weight based on Kautsohuk ingesetst. At a lower dosage there is insufficient frost protection. With a larger dosage comes bleeding, which is also undesirable. One disadvantage of the DADM is that it is strongly discolored on the Lioht and that this light discoloration is also evident in the Dosage of 0.3-0.6% required for natural rubber (based on rubber) still very annoying.

Synthetic rubber types, such as butyl rubber, neoprene, which against Oxidation by atmospheric oxygen and oson to a large extent stable are, do not show the frosting appearance. Butadiene-based rubber vulcanizates can, however, show the frosting phenomenon again. About these types of rubber include polybutadiene, polybutadiene styrene, polybutadiene acrylonitrile and other copolymers of butadiene. If you apply these rubber compounds in the same way as natural rubber compounds o, 3 -o, 6 gens. % (based on rubber) DADM as a means to prevent frosting on, as with natural rubber, there are discoloration phenomena due to light, unless these mixtures are filled to a high degree with soot. This discoloration occur in almost all cases where colored vulcanizates are present. To anyway to be able to produce lightfast colored vulcanizates based on butadiene without if frosting occurs, the rubber compounds are coated with protective waxes such as ceresin added. As a result of their specific microcrystalline These waxes migrate to the surface and are in this way in the structure Able to suppress frosting. Apart from unwanted surface appearances However, such waxes can also have a negative influence, for example on the adhesive properties to have.

In some cases, therefore, such waxes are also undesirable.

In addition, it is not always possible to use a high enough 'dosage provided in order to achieve a safe effect for as long as possible.

The object of the invention is to provide a method in which vulcanizates from colored butadiene-based rubber mixtures in general with long-lasting Effect a protection against frosting.

A surprising solution has been found that in the case of colored vulcanizates made from the butanediene-based rubber types mentioned, frosting can be prevented by adding 0.05-0.15, preferably 0.1% by weight (based on rubber) of a diaminodiphenylalkane to the mixture or its substitution product adds the following structure.

R denotes H or an alkyl group with 1-5 carbon atoms. Such against Vulcanizates protected from frost formation show physical properties that are opposite to the other DADM-free vulcanizates have no disadvantages. The frosting protection is practically unlimited and is also due to the influence of temperature over a longer period of time, which are acceptable for these vulcanizates are not weakened. Nor does it occur Light discoloration more. Furthermore, there are unfavorable physiological side effects this low dosage can no longer be encouraged.

The invention is illustrated by means of the following examples. The three The following mixing recipes are based on 6 different types of rubber back, whereby the mixture specified in the third recipe is natural rubber as Contains basis of comparison.

Example Is Perbunan N 2807 or Perbunan N 2818 100.0 parts by weight Stearic Acid 1.0 "Zinc Oxide 5.0" "Hard Clay 50.0" "Ultramarine Blue 5.0" "Carbon Black 0.8 "" sulfur 2.0 "benzothiazyl-2-cyclohexylsulfonamide 1.0 n lt diphenylguanidine 0.5 "" 165.3 parts by weight Example 2s Buna Hüls 152, Buna Hüls 321 or Buna CB 100.0 parts by weight stearic acid 1.0 zinc oxide 5.0 hard clay 5o, o lt ultramarine blue 5, o carbon black, 8 sulfur 2, o benzothiazyl-2-cyclohexylsulfenamide 1.0 "diphenylguanidine 1.0 "165.8 parts by weight Example 3: Natural rubber 100, o parts by weight stearic acid 1.0 Zinc oxide 5.0 "hard clay 50.0" ultramarine blue 5.0 "carbon black 0.8 sulfur 2.5 benzothiazyl-2-cyclohexylsulfenamide 0.6 Diphenylguanidine 0.5 165.4 parts by weight In recipe 1, the two types of rubber are Perbunan N 2807 and Perbunan N 2818 are used. In recipe 2 there are Buna pods 152, Buna Hüls 321 and Buna OB used. Those obtained according to these recipes Mixtures were vulcanized at 1430 C for 30 minutes. The vulcanizates became Cut panels that have been subjected to a frosting test. The frosting test was carried out in a drying cabinet at 450 ° C.

The following table shows the result of the test. The table 1 shows frosting after a test duration of 24 hours. Table 2 shows the exposure test for discoloration with decreasing dosage of DADM on a vulcanizate from a light gray Perbun mix.

Table 1: Mixture number / addition of 4,4'-diaminodiphenylmethane Rubber type in% on elastomer 0 0.33 0.16 0.08 I / Perbunan N 2807 +++ - - - II / "N 2818 +++ - - - III / Buna sleeve 152 +++ - - - IV / Buna sleeve 321 +++ - - - V / Buna CB +++ - - - VI / natural rubber +++ + ++ +++ no frosting +++ = very freezing ++ - very freezing + = freezing Table 2s Type of exposure Dosing of 4,4'-diaminodiphenyl methane in% on elastomer 0.66% 0.33% 0.16% 0.08% 0% 14 days of sunlight the laboratory roof (samples +++ ++ + - | - partially covered) 96 hours of xenon lighting with water sprinkling ++++ +++ ++ + + - - no discoloration ++++ = very strong discoloration +++ strong discoloration ++ = discoloration + - incipient discoloration A series of tests with 4,4'-diamino-3,3'-dimethyldiphenylmethane leads to largely the same result. The other substitution products of the diaminodiphenylalkane outlined above also show a similar behavior.

Claims (1)

P a t e n t a n s p r u c h Process for preventing frosting in colored vulcanizates made of butadiene-based rubber and customary additives, characterized in that the mixture, prior to vulcanization, is 0.15, preferably about 0.1% by weight (based on rubber) of a diamino-dephenylalkane or its substitution product Structure is added: RIH or alkyl group with 1 5 3