DE3431694A1 - Cyclic ketals of polyols, their preparation and use as non-discolouring ozone inhibitors - Google Patents

Abstract

Ketals of tri- to hexols and ketones of the formulae <IMAGE> in which R denotes hydrogen or methyl and R1 denotes C1-C4-alkyl, are suitable as ozone inhibitors for natural and synthetic rubber.

Description

BAYER AKTIENGESELLSCHAFT 5090 Leverkusen, Bayerwerk Group Administration RP

Patent department Jo / Kü-c 2. 7. often 84

Cyclic ketals of polyols, their production and use as non-discoloring ozone protection agents

The invention relates to condensation products of tri-, tetra-, penta- and / or hexaols with ketones formula

■ R "/" λ-C-R, or O

wherein

R identical or different, hydrogen or methyl and

R _{1 is} Cj-C.-alkyl,

in a molar ratio of 1: 1 to 1: 3, in which all keto groups are completely acetalized.

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Further objects of the invention are a process for the preparation of the condensation products and their use as anti-ozone agents in natural and / or synthetic rubber as well as those with anti-ozone agents stabilized rubbers.

The following alcohols with 3, 4, 5 or 6 hydroxyl groups may be exemplified as tri-, tetra-, penta- and hexaols called:

Glycerol-1,1,1-trimethylolether, 1,1,1-trimethylolpropane, 1,1,1-trimethylolbutane, 1,2,6-hexanetriol, Pentaerythritol, sorbitol, mannitol, 2,2,6,6-tetramethylolcyclohexanol.

The following condensation products are possible:

a) Triol-ketone condensation products in a molar ratio 1: 1 and 1: 1.5

b) Tetraol-ketone condensation products in a molar ratio 1: 1 and 1: 2

c) Pentaol-ketone condensation products in a molar ratio 1: 1, 1: 1.5, 1: 2 and 1: 2.5 and

d) Hexaol-ketone condensation products in a molar ratio 1: 1, 1: 2, 1: 3.

The polyols mentioned can be condensed with the ketones by known processes.

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It constitutes Polyhydroxy1verbindung with the ketone in the presence of catalytic quantities of an acid dehydration catalyst at temperatures of 0-200 ⁰ C, preferably 20-120 ⁰ C, wherein per mole of alcohol 1 to 3 moles of ketone.

The reaction can be carried out without a solvent or in the presence of solvents. As a solvent are both polar, such as methanol, ethanol or dioxane, and non-polar, such as gasoline, benzene or Toluene, suitable. If water-immiscible solvents are used, these can optionally be used for azeotropic distillation of the water formed during the condensation.

Acid dehydration catalysts which may be mentioned are HCl, phosphoric acid, ZnCl- / H ₃ SO ₄ , benzenesulfonic acid, naphthalenesulfonic acid or p-toluenesulfonic acid, preferably p-toluenesulfonic acid.

The catalysts are preferably used in a dosage of from 0.05 to 5, particularly preferably from 0.1 to 1% by weight, based on the aldehyde, used.

The condensation products according to the invention can be natural and / or synthetic rubbers are added in order to stabilize them against the degradation by ozone.

The condensation products according to the invention can easily be distributed in rubber mixtures and can be used in

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Connection with the commonly used rubber chemicals (e.g. vulcanization accelerators, vulcanizing agents, Anti-aging agents, plasticizers, fillers, waxes, dyes, etc.) are used, without affecting their specific effect.

The condensation products according to the invention are added to the rubber in such amounts that one Stabilization against degradation by ozone occurs. The appropriate amounts are those of ordinary skill in the art common or easy to determine.

The dosage of the new products in the polychloroprene rubber is, for example, between 0.1 and 6.0 % By weight, preferably 0.3 to 3.0% by weight, based on the polymer content, that consists of 100.0% by weight of polychloroprene or polychloroprene with a co-vulcanizable rubber, the minimum content of Polychloroprene is 20% by weight, preferably 30%.

Suitable cocurable with polychloroprene rubbers include natural rubber or synthetic rubber-like polymers that contain double bonds and be obtained for example, from conjugated diolefins such as butadiene, dimethylbutadiene, isoprene and its homologues or copolymers such conjugated diolefins having polymerizable vinyl compounds such as styrene, Qt -Methylstyrene, acrylonitrile, methacrylonitrile, acrylates, methacrylates.

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Are the condensation products according to the invention Added to rubber types other than the polychloroprenes mentioned, a combination is recommended with waxing, since such a combination is a synergistic one Shows effect.

The weight ratio of wax to that of the invention Condensation products can vary within wide limits, preferably between 0.25 and 2.5 to 1.

The waxes consist at least partially of microcrystalline paraffins. Macrocrystalline paraffins are those whose refractive index is njl lower lies than that according to the equation:

n _D = 0.00035 + 1.4056 t = freezing point in ⁰ C calculated,

while microcrystalline paraffins represent those whose refractive index is higher than that according to the formula calculated above (compare also for the definition Petroleum Waxes, Proceedings of ASTM-TAPPI Symposium on Petroleum Waxes, Feb. 63, TAPPI-STAP No. 2, pp. 1 to 19).

Suitable rubbers are natural rubber or, in addition to polychloroprene, synthetic, rubber-like polymers, which still contain double bonds and which, for example, consist of conjugated diolefins such as butadiene, dimethyl

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butadiene. Isoprene and its homologues, or copolymers conjugated in this way Diolefins with polymerizable vinyl compounds, Acrylates and methacrylates.

The synergistic ozone protection wax combination is added to the rubbers in such amounts that a stabilization against the breakdown by ozone occurs. The appropriate amounts are those of ordinary skill in the art common or easy to determine. The dosage is, for example, between 0.5 and 5% by weight, preferably between 1 to 10% by weight, based on the polymer content.

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example 1

Condensation product of pentaerythritol with 4-acetylcyclohex-1-ene

183 g of 4-acetylcyclohex-1-ene were placed in a stirred tank with a water separator with 100 g of pentaerythritol, 4.6 g of 85% phosphoric acid in 800 g of xylene. The mixture was then boiled until the separation of water ceased. The residue at about 0.2 mbar (160 ⁰ C head temperature) was then distilled, after distilling off the solvent. After two ümkristallisation of the distillate thus obtained to obtain a solid of melting point 92-94 ⁰ C.

Example 2

The following rubber mixture was produced on the roller:

Polychloroprene magnesium oxide Stearic acid

Precipitated silica 20 (BET value: 180 m ³ / g)

Soft clay, titanium dioxide, antimony oxide

Naphthenic mineral oil plasticizer Chlorinated paraffin

Ethylene thxourea

zinc oxide

Anti-ozone agents according to tables

100.0 parts by weight 4.0 parts by weight 0.5 part by weight

20.0 Weight Parts 170.0 Weight Parts 5.0 Weight Parts 5.0 Weight Parts 20.0 Weight Parts 10.0 Weight Parts 1.2 Weight Parts 5.0 Weight Parts

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Test specimens 0.4 4.5 4.5 cm were vulcanized from these mixtures (compressed air vulcanization for 30 min at 150 ^° C.). 4 test specimens each were then clamped in a plastic frame in such a way that elongations of 10, 20, 30 and 60% occur on the surface.

The tensioned test specimens were tested with an air stream that contained 1000 parts of ozone per 100 million parts of air, treated at room temperature. After 2, 4, 6, 8, 24, 48, 96 and 168 hours, the samples were with the Eye checked for any cracks. The table below shows the hours until the first crack formation registered. The experiments were terminated after 168 hours.

Table 1

Elongation in%

10 20 30 60

Without ozone protection agent 24

Product according to example 1

0.5 part by weight - ^ 168 ^ 168 24 6 1.0 parts by weight> 168> 168> 168> 168

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Claims (10)

Patent claims l.j condensation products of tri-, tetra-, penta- and / or hexaols with ketones of the formulas * / y ~ CR ₁ or in which R identically or differently hydrogen or methyl and mean, in a molar ratio of 1: 1 to 1: 3, in which all keto groups are acetalized. 2. Condensation products from triplets with the ketones according to claim 1 in a molar ratio of 1: 1 and 1: 1.5, in which all keto groups are acetalized. 3. Condensation products of tetraols with the ketones according to claim 1 in a molar ratio of 1: 1 and 1: 2, in which all keto groups are acetalized. Le A 23 288 4. Condensation products of pentaols with the ketones in a molar ratio of 1: 1, 1: 1.5, 1: 2 and 1: 2.5, in which all keto groups are acetalized. 5. Condensation products of hexaoles with the ketones in a molar ratio of 1: 1, 1: 2, 1; 3, in which all keto groups are acetalized. 6. Process for the production of condensation products according to claims 1-5, characterized in that that tri-, tetra-, penta- and / or hexaols are reacted with the ketones according to claim 1 1 to 3 moles of aldehyde are used per mole of alcohol. 7. The method according to claim 6, characterized in that the alcohols are reacted with the ketones in the presence of catalytic amounts of an acidic dehydration catalyst at temperatures from 0 to 200 ^° C., 1-3 moles of aldehyde being used per mole of alcohol. 8. Anti-ozone agents for natural and / or synergistic rubber containing condensation products according to Claims 1 to 5. 9. Process for stabilizing natural and / or synthetic rubbers against ozone depletion by adding ozone protection agents, thereby Le A 23 288 indicates that a condensation product according to claims 1 to 5 is used as the ozone protection agent added in effective amounts. 10. Natural and / or synthetic rubber stabilizes against ozone depletion after a The method of claim 9. Le A 23 288