DE2165198A1 - Abrasion-resistant rubber vulcanisates - containing silica as reinforcing pigment and an azidoformiate as vulcanising agent - Google Patents

Abstract

Abrasion-resistant vulcanisate comprises rubber (e.g. SBR), a finely-divided reinforcing silica pigment, and an azidoformiate of formula : where x is 1-4, and R is an organic residue with >=1 C atom per azidoformiate gp., and contg. a functional gp., which can combine with the silica pigment when x is 1. Triethysilylpropyl- and/or diethyleneglycolbis-(azidoformiate) is suitable. Used in mfr. of rubber articles subjected to heavy abrasive stresses.

Description

LAWYERS 2! O 5 1 9

DR. JUR. DIPL-CHEM. WALTER BEIL

ALFRED HOEPPENER oo _{n 1fvM}

DS. JifR. DIPL-CHEM. H.-J. WOLFP ^ ^o 'U0Z.l37T

DK. j ·; «; HANS CHR. AX

FSAMi (FiIRrAM MAIN-HIGH

Our No. 17 586 -

PPG Industries, Inc. Pittsburgh, Pa. 15222, USA

Abrasion-resistant rubber vulcanizates

The present invention relates to rubber vulcanizates, in particular abrasion-resistant rubber vulcanizates, which for use in rubber strips and for other purposes where abrasion resistance is desired.

It has been found that by using an azidoformate as a vulcanizing agent, silica-reinforced rubber vulcanizates can be produced which have a surprisingly high abrasion resistance.

Those suitable for the compositions according to the invention Azidoformate vulcanizing agents can be represented by the following general formula

O R (ocn ₃ ) _x

in which χ is an integer from 1 to 4 and R is an organic Radical with at least 1 carbon atom per azido

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means formate group, where R is a functional group contains, which deals with the silica pigment in the, rubber composition can connect if χ means 1. The azidoformates are preferred in which χ is greater than 1, preferably 2.

Suitable organic radicals for R are, for example, alkyl, cycloalkyl, alkaryl, aralkyl and aryl radicals ^ the ether and may contain thioether bonds which chemically or physically interact with the reinforcing agent Can connect silica pigment. Suitable functional groups are, for example, those represented by the following formula groups

Xn

"M (3-n)

in which X denotes a radical which reacts with the silanols (hydroxysilanes) present in the precipitated silica, as a result of which the silicon atom can be bonded to an oxygen atom of the silicon dioxide. X can mean, for example, a halogen such as chlorine or bromine or an oxy group OR ·, R ^f and M can be relatively inert radicals such as X, H, alkyl, cycloalkyl, aryl, aralkyl, alkaryl, acyl radicals, where one of these groups is substituted by a halogen atom such as chlorine or bromine, or a radical ;; which reacts with the silanols contained in the precipitated silicon dioxide, such as X. R, R ¹ and M preferably contain 1 to 10 carbon atoms, and η is an integer from 1 to 3, preferably 3.

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Suitable azidoformates are, for example, trimethoxysilylethyl azidoformate, triethoxysilylpropylazidoformate, tetramethylene bis (azidoformate), pentamethylene bis (azidoformate), 1, 4-Cy c lohe xan dimethy ibis (azido formmate), /, 9 ^ -p-xoformate, azidoformate 2,2-isopropylidene bis (p, p'-phenyl azidoformate), 2,2'-0xydiäthylbis (azidoformate), 2.2 ^I -Oxydipropylbis (azidoformate), 2,2'-ÄthylendioxydiäthyIbis (azidoformate), 2,2'- Ethylenedioxydiethylbis (azidoformate), 2,2'-thiodiethyIbis (azidoformate) and 4,4'-thiodibutylbis (azidoformate). Other suitable azidoformates are disclosed in German Patent 1,965,514.

The azidoformates used according to the invention can by Reaction of a chloroformate with an excess of alkali azide, as described in United States Patent 3,211,752 issued October 12, 1965 will.

Some of the low molecular weight azido formates are somewhat sensitive to shock. When using a dispersion from about 50 wt. Azidoformate on an inert carrier such as non-precipitated silica made by oxidative hydrolysis of silicon tetrachloride and under commercially available under the trade name Cab-O-Sil but no explosive properties.

Silica suitable for the invention is finely divided precipitated silica, possibly in combination with an insoluble silicate, with poor gel-forming properties. These substances can be produced by destabilizing soluble silicates under various conditions that prevent the formation of a continuous gel, such as the addition of a precipitating salt. The silica generally contains at least 50 %, primarily

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preferably at least 80 % SiOp, measured on an anhydrous basis (where bound and free water are excluded) and has a BET surface area (measured using nitrogen gas) between about 50 and 600 m per g, before «u

ρ
preferably between 70 and 300 m per g, and a mean outermost particle size between about 50 and 10,000 angstroms, preferably between about 50 and * t00, in particular between 150 and 300 angstroms. The BET method of measuring surface area is described in the Journal of the American Chemical Society, vol. 60, p.304 (1930). Suitable silica and a method of making it are described in United States Patent 2,805,955 issued September 10, 1957 and United States Patent 2,910,830 issued June 14, 1960.

The elastomers (also called rubbers here) that are used in the compositions according to the invention (here also vulcanizates may be used include natural rubber and synthetic rubbers. Suitable synthetic Examples of rubbers are butadiene styrene / copolymers, Butadiene acrylonitrile / copolymers, butadiene isobutylene / copolymers (Butyl rubber), synthetic elastomers, obtained by polymerizing butadiene, chlorobutadiene, Isoprene and the like alone or with other polymerizable substances such as styrene, methyl methacrylate, Methyl chloroacrylate, acrylonitrile, vinyl chloride and their Equivalent.

The vulcanizates according to the invention preferably contain an antioxidant in small but effective amounts. Suitableί Antioxidants are, for example, N, N'-diphenylethylenediamine and N, N'-di-o-tolylethylenediamine, toluene-2,4-diamine, N-phenyl-2-naphthylamine, alkylated diphenylamine and a - ^ efcwi-Diphenylamine reaction product. If necessary, can

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also other conventional additives such as carbon blacks, oils and Dyes are used. However, the addition of activators, accelerators and sulfur is necessary and is harmful in most cases. The vulcanizates according to the invention can be between 5 and 100 parts by weight, preferably contain between 40 and 80 parts by weight of silica per 100 parts of rubber (parts per 100). The azidoformate vulcanizing agent may be in an amount between about 0.2 and 20, preferably between about 0.5 and 10 Parts per 100 are used. The antioxidant can be in an amount between about 0.5 and 3, preferably between about 1 and 2 parts per 100 can be used. Other ingredients can optionally be used in the usual percentage Proportions are used. The vulcanizates can be prepared by conventional methods such as those shown below Examples are described.

example 1

Elastomers A to F listed in Table 1 below were prepared by mixing the first 7 ingredients in a Brabender for 10 minutes at a temperature between about 93 and 116 ° C, after which the remaining ingredients were added with mixing in an open mill. The mixing in the mill was continued for about 10 minutes at about 50 ⁰ C.

Table 1

Elastomers A B C D ^ F components parts by weight

SBR-16O1- ^/ 150 150 -

SBR-15O2- ^/ - - 100 100 100 100

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Table 1 continued
Hi-SiI 233 ^ - - 50 50 50 50

SilaiBA-189- - - - - - 1.0

Sample 363-4l9- ^/ - - - - 1.5 -

1.0 1.0 1.0 1.0 1.0 1.0

4.0

1.5 -

1.5 - -

2.4

PBNA- ⁷ 1.0 zinc oxide 4.0 MBTsl ⁷ 0.7 DOTG ^ 0.6 sulfur 1.85 Sample 363-425- ⁷

1 / SBR-I6OI is a non-oil-extended styrene-butadiene rubber with 50 parts of N-330 carbon black (HAP) per 100 parts SBR

2 / SBR-1502 is a low temperature polymerized Styrene-butadiene copolymer

V Hi-SiI 233, trademark of PP.Q Industries, Inc. A precipitated water-containing silica with an outermost particle size of 200 Angstroms, a BET surface area of about 150 m per gram and a SiO ₂ content of 87.5 %, CaO - 0.75 %, R ₃ O ₃ (Al ₂ O ₃ + Pe ₃ O ₃ ) 0.95 %, NaCl - 1.6%, a weight loss at 105 C of 6.3 % » and the rest is bound Water.

Jt / Silane A-189 is a trademark of Union Carbide Corp. for trimethoxysilylpropy! mercaptan.

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5 / sample 363-419 is triethoxysilylpropylazidoformate.

y PBNA is N-phenyl-2-naphthylamine.

V MBTS is 2 _S 2-dithiobisbenzothiazole.

8 / DOTQ is NjM'-di-o-tolylguanadine.

£ / sample 363-425: diethylene glycol bis (azidoformate).

The vulcanized compositions obtained were subjected to various tests (infra tests), and the Results are shown in Table 2 below,

Table 2 Physical Properties

Elastomers A B £ £ E F

Push-pull properties 1 '

Tensile strength kg / cm ² 282 266 173 266 301 250

Module at $ 300

(kg / cm ² ) elongation I69 112 64 58 113 122

% Elongation 460 530 500 810 58O 470

Hardness (Shore A) - ^/ 67 63 77 78 68 63

Pico abrasion index ⁷ 101 86 56 118 106 118

JL / Tested to ASTM D-412-49T.
2 / Tested according to ASTM D-314.

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3 / Tested according to ASTM D-2228-63T.

When looking at the data listed, it can be seen that of the two carbon black-reinforced vulcanizates A and B vulcanizate A, which contains sulfur and conventional accelerators as a conventional vulcanizing agent, has better abrasion resistance than vulcanizate B, which contains azidoformate as a vulcanizing agent. at However, the silica-reinforced vulcanizates C, D, E and P have the vulcanizates D, E and P, which is an azidoformate contained as a vulcanizing agent, a better abrasion resistance than the vulcanizate C, which the conventional Vulcanizing agent contains sulfur and conventional accelerators.

Example 2

The vulcanizates listed in Table 3 were prepared by adding the first 8 ingredients in a Banbury 8 minutes at a temperature between about 1 ^ 9 and 177 ° C after which the remaining ingredients were added with mixing in an open mill. The mixing the open mill continued for about 10 minutes at 82 ° C.

Table 3

Vulcanizates G H I J K L M

Components
(Parts by weight):

SBR-1502 98 100 100 100 100 100 100

Hi-SiI 233 60 60 60 60 60 -

N-285 Black ¹ / - - - - 60 60

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Continuation of table 3

Sundex 790- 10 10 10 10 10 10 10

Flexmine- ^ 1 1 1 1111

PBNA 1 111111

Stearic acid 1 111111

Zinc oxide - 4

MBTS 1.5-0.8

DOTG 1.5 0.3

Sulfur 2.4 - - - 0.5 1.85 -

ZnO Master- ^ 6 ______

S-3OO9-5 / Crosslinker - 6 8 10 8 - 8

1 / Standard ASTM designation

2 / Sun Oil Company's trademark for an aromatic oil.

_5 / Trademark of the United States Rubber Company. A physical mixture containing 65 % of a complex diarylamine-ketone reaction product and 35 % of a commercially available Ν, Ν'-diphenyl-p-phenylenediamine.

jt / A mixture of 100 parts of SBR-1502 and 200 parts Zinc oxide.

_> / Trademark of Hercules Powder Company, for one 36 C-bis (azidoformate).

The vulcanizates listed in Table 3 were subjected to various tests (infra tests) and the results are listed in Table 4 below.

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- ^lo "

Table 4

Elastomers G '(£' H I. J K 162 too ! 189 211 184 L. M. Mooney Scorch Test at 132 ° 145 i I85 2o3 179 Minutes to reach > 3o 153 72 i I72 2I0 19o from point 5 3.S I 3.5 3.1 3.6 73 I7.3 2.6 ML 4 min. At 100 ^{0 C-7} 154> 2oo> 2oo> 2oo> 2oo 74 7o 89 Push-pull own
properties - 51, 3 72 91 72 Tensile strength (kg / cm ² ) 57 76 91 72 2o min. At 149 ⁰ C 194 57 72 9o 74 212 2o5 3o min. 135 2o3 2ol 45 min. 13o Γ8ο 72o 680 7oo 243 2oo Modules at 3oOp! & Iger 5oo 76o 7oo 64o 7oo Elongation (kg / cm) 5oo i 7oo 650 72o 2o min. At 149 ° C 5o, 6 86.5 127 3o min. 54.8 7o 73 77 75 137 127 45 min. 57 72 75 77 75 157 130 % Elongation 72 76 78 75 2o min at 149 ⁰ C 64o ^r i 53o 46o 3o min. 43o 46o 45 min. 45o 48o Hardness (Shore A) ^ 2o min. At 149 ° C 67 65 3o min. 68 65 45 min. 69 64 Goodrich Plexometer-i · '

17-1 / 2Ϊ - loo ° C - 11.5 kg / cm

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Port setting Table 4

Hardening:

45 min. At 149 ° C

T ⁰ C 31.1 46.7 41.1 31.7 30.6 18.9 22.2

permanent deflection 11.2 27.9 19.6 12.8 23.3 12.5 3.1

Pi co-Abri eb-Index—

Hardening:

30 min. At 149 ° C 63 113 121 112 122 208 I6I 45 min. At 149 ° C 61 117 129 127 126 219 I69

1 / Get% tet according to ASTM D-1646-63

2 / Tested according to ASTM D-412-64 T

3 / Tested according to ASTM D-2240-64 T

47 Tested according to ASTM D-623-62

£ / Tested according to ASTM D-2228-63 T

From the data listed in Table 3/4 it can be seen that the silica-reinforced azidoformate vulcanizates H, I and J have considerably greater abrasion resistance than conventional silica-reinforced vulcanizate G. Fon the two carbon black-reinforced vulcanizates L and M has the vulcanizate M, which is an azidoformate as vulcanizing agent contains, a significantly lower abrasion resistance than the vulcanizate L, the sulfur and the contains conventional accelerator. From this data it can also be seen that there is a mixture of azidoformate crosslinking agents such as a bis (azidoformate) believed to be the

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Rubber cross-linked or vulcanized, and a Monoazidoformiat containing a silicon atom takes from the one that it serves as a coupling agent between the rubber and the silica pigment.

Example 3

If the above examples are repeated using Ν, Ν'-di-o-tolylethylenediamine, N ₉ N ^f -diphenylethylenediamine and toluene-2,4-diamine instead of the antioxidant N-phenyl-2-naphthylamine, Ultrasil VN 3 (a trademark Degussa for silicon dioxide) instead of Hi-SiI 233, natural rubber instead of SBR, and the other azidoformates listed in the description instead of triethoxysilylpropylazidoformate, diethylene glycol bis (azidoformate) and the high molecular weight 36 C bis (azidoformate) were also good results.

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Claims (12)

Patent claims: (%. Abrasion-resistant vulcanizate made of rubber, a finely divided reinforcing silica pigment and an azide formate of the general formula Il in which X is an integer from 1 to 4 and R is an organic Is a radical having at least 1 carbon atom per azidoformate group, where R is a functional group which can combine with the silica pigment when χ is 1. 2. Vulcanizate according to claim 1, characterized in that x means 2. That R contains a functional group 3. The vulcanizate of claim 1, characterized in that can connect with the reinforcing silica pigment. 4. Vulcanizate according to claim 1, characterized in that the functional group Xn -si / M (3-n) in which X is a radical that reacts with the silanols present in the silica _s M is a relatively inert radical that reacts with the silanols present in the silica ,? G 9 H: U / 1 0 1 5 held silanols reacts, and η is an integer of 1 to 3 means. 5. Vulcanizate according to claim 4, characterized in that X is an alkoxy group having 1 to 10 carbon atoms
and η means 3. 6. Vulcanizate according to claim 1, characterized in that R is an alkyl radical having 1 to 10 carbon atoms and χ 2 means. 7. Vulcanizate according to claim 1, characterized in that that the azidoformate triethoxysilylpropylazidoformiat 8. vulcanizate according to claim 1, characterized in that the azidoformate diethylene glycol bis (azidoformate) $. Vulcanizate according to claim 1, characterized in that that the rubber is natural rubber. 10. Vulcanizate according to claim 1, characterized in that the rubber is a copolymer of butadiene and styrene is. 11. Vulcanizate according to claim 1, characterized in that a mixture of mono- and bis (azidoformates) is used will. 209Ö34 / 1016 12. Vulcanizate according to claim 11, characterized in that that the mixture of diethylene glycol bis (azidoformate) and Triethoxysilylpropylazidoformiat consists. For: PPR Industries, Inc. PittsburRh / Pa. 15222, USA (Dr F.JVWolff) Lawyer 209834/1015