MXPA97008919A - Vulcaniza hule compositions - Google Patents

Abstract

The present invention relates to a vulcanizable rubber composition containing a self-condensing alkylated triazine resin additive for improved adhesion of tire wires, reinforcements of the side walls and / or rubber firmness, without the use of resorcinol or Equivalent co-reactive resorcin

Description

VULCANIZABLE RUBBER COMPOSITIONS BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to rubber compositions having excellent strength or rubber resistance, reinforcement of the sidewall of the tire and / or adhesion to the ropes, which employs resin additives. of self-condensable alkylated triazine with high content of imino and / or methylol functionality, in the substantial absence of resorcinol or equivalent resorcinol co-reactants (methylene acceptor co-reactants). Related Prior Art An organic rubber additive widely used to improve the adhesion of vulcanized rubber to steel strings coated with bronze and polyaramide or polyester rope comprises the combination of hexametoxymethylmelamine and resorcinol. In addition, hexamethylenetetramine is sometimes used in combination with resorcinol. These combinations of organic compounds are very effective for the purpose, but the use of resorcinol presents risks of bad odor and possibly toxic risks during the processing of the rubber, due to the excessive smoke emission of the resorcinol. The vulcanizable resorcinol-free rubber compositions are known. For example, the Patent of E.U.A. REF: 25914 No. 5,298,539 discloses vulcanizable rubber compositions containing uncured rubber, a vulcanizing agent and at least one additive selected from the group consisting of melamine, acetoguanamine, benzoguanamine, cyclohexylguanamine and glycoluril monomer derivatives, and oligomers thereof. monomers These derivatives are substituted on average in two or more positions on the monomer, or each unit of the oligomer with radicals terminated in vinyl, and the composition is free of resorcinol. Another way of removing resorcinol from vulcanizable rubber compositions has depended on the use of alternative co-reactants. The Patent of E.U.A. No. 4,038,220 discloses a vulcanizable rubber composition comprising a rubber, a filler material, N- (oxymethyl substituted) melamine and at least one of a or β-naphthol. This reference uses monohydric phenols, a or ß naphthol, as methylene acceptors in the reaction that forms the resin during vulcanization, in the absence of resorcinol. The use of resorcinol-formaldehyde resin to replace resorcinol in vulcanizable rubber compositions is also known. A. Peterson, et al., "Resorcinol Bonding Systems for Steel Cord Adhesion", Rubber World (August 1984).

Notwithstanding the various proposals made to avoid the use of resorcinol in vulcanizable rubber compositions, there is a continuing need for vulcanizable rubber compositions containing economical, commercially available additives that improve the adhesion of vulcanized rubber to tire threads, and improve the Firmness of the rubber without the use of resorcinol. None of the references mentioned above describes or suggests the use of self-condensing alkylated triazine resins with high content of imino and / or methylol functionality in vulcanizable rubber compositions, in the absence of resorcinol as an adhesion promoter or rubber hardener. BRIEF DESCRIPTION OF THE INVENTION The present invention is broadly directed to a vulcanizable rubber composition comprising: (a) an uncured rubber; (b) a self-condensable alkylated triazine resin having a high content of imino and / or methylol functionality, represented by the formula (I) wherein Z is selected from the group consisting of -N (R) (CH? OR1), aryl having from 6 to 10 carbon atoms, alkyl having from 1 to 20 carbon atoms, and an acetyl group, each R is independently selected from the group consisting of hydrogen and -CH2OR "\ and each R1 is independently selected from the group consisting of hydrogen and an alkyl group having 1 to 12 carbon atoms, provided that at least one R is hydrogen or - CH2OH, and at least one R1 is an alkyl group having from 1 to 12 carbon atoms; and (c) a vulcanizing agent, the vulcanizable rubber composition is substantially free of resorcinol, and more preferably substantially free of methylene acceptor co-reactants. For purposes of the present invention, and for clarification, "substantially free" of resorcinol or methylene acceptor co-reactants means that such co-reactants are at most only present in minor amounts, for example, as impurities in the other components of the vulcanizable rubber compositions present. This is to distinguish clearly from the vulcanizable compositions of the prior art, which typically require the presence of resorcinol or other methylene acceptor co-reactants, in amounts of the same order of magnitude as the methylene donor (eg the triazine reagent). ). In the formula (I) above, Z is preferably -N (R) (CH? OR1), phenyl, methyl or cyclohexyl. More preferably, Z is -N (R) (C? ^ OR1), that is, a melamine derivative. Preferably, at least 2, more preferably at least 3 of the R groups of the triazine resin are hydrogen and / or -CH 2 OH. It is also preferred that at least one, more preferably at least two of the groups R1 be a lower alkyl group having from 1 to 6 carbon atoms, more preferably methyl or butyl. More preferably, R is hydrogen, and R1 is a mixture of hydrogen and methyl The self-condensable alkylated triazine resin employed in this invention may also be an oligomer of the triazine resin of Formula (I), or a mixture of triazine monomeric and the oligomers thereof. The oligomers of this invention include dimers, trimers, tetramers, and the like of the triazine compound of Formula (I). Generally, such oligomers are linked by a methylene radical, or the radical -CH2OCH2-, and at least one R group of the oligomer is hydrogen. Also, the self-condensing triazine resin is preferably absorbed onto a solid support, which allows the self-condensing triazine to be present in the vulcanizable composition in the form of a dry powder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The vulcanizable rubber compositions of this invention advantageously employ self-condensing alkylated triazine resins having a high content of imino and / or methylol functionality, represented by Formula (I), without the need for resorcinol or its equivalent, that is, without the need for co-reactive methylene acceptors. It is believed, in the prior art compositions, that the alkoxymethylmelamines or hydroxymethylmelamine in the rubber compositions form a network through the reaction with the resorcinol, to improve adhesion to the tire yarn. Without being limited by theory, it is believed in the present invention that the high reactivity of the self-condensable alkylated triazine resins having a high content of imino and / or methylol functionality allows these resins to self-condense and form a network , to improve the adhesion to the tire cord and / or the reinforcement of the side wall in the vulcanized rubber obtained from the vulcanizable compositions of the present invention, without the need for resorcinol (or methylene acceptors in general) as a co-reactant. Examples of commercially available high-content alkylated triazine resins for use in the vulcanizable rubber compositions of this invention include, without limitation: a methoxymethyl melamine-formaldehyde resin with high imino content, having 3.8 units of combined formaldehyde and 2.8 units of methyl groups per unit of melamine (MF3.?Me2.8), 34% molar NH, 56% molar methylation, 10% molar methylol and a degree of polymerization of 1.8; a mixed resin of methoxymethyl / butoxymethyl melamine formaldehyde with a high content of imino having 3.8 units of combined formaldehyde, 1.7 units of methyl groups and l.ß units of n-butyl groups per unit of melamine (MF3.aMe: .7Bu? .6), 31 mol% NH, 34 mol% methoxy, 32 mol% n-butoxy; 3% molar of methylol and a degree of polymerization of 2.3; a methoxymethyl melamine-formaldehyde resin with a high imino content, having 4.0 units of combined formaldehyde and 2.8 units of methyl groups per unit of melamine (MF4.oMe2.8), 30% molar NH, 58% molar methylation, 12 mol% of methylol and a degree of polymerization of 2.3; a methoxymethyl melamine-formaldehyde resin with a high imino content, which has 4.4 units of combined formaldehyde and 3.3 units of methyl groups per melamine unit (MF4.4Me3.3), 22 mole% of NH, 66 mole% of methylation, 18% molar of methylol and a degree of polymerization of 1.75; and a butoxymethyl melamine-formaldehyde resin with a high imine content, having 4.1 units of combined formaldehyde and 2.7 units of n-butyl groups per unit of melamine (MF4.?Me2.7), 26% molar NH, 58% butyl molar, 16 mol% of methylol and a degree of polymerization of 2.7; Examples of commercially available methylol-functionalized triazine resins include, without limitation: a melamine resin with ethoxymethyl-methylol functionality having 4.9 units of combined formaldehyde and 2.4 units of methyl groups per unit of melamine (MF.9Me2.4 ), 12 mol% NH, 48 mol% methyl, 40 mol% methylol and a degree of polymerization 2.0; and a melamine resin with methoxymethyl-methylol functionality having 5.3 units of combined formaldehyde and 3.3 units of methyl groups per unit of melamine MF5.JA 3.3), 4 mole% of NH, 66 mole% of methylation, 30 mole% of methylol and a degree of polymerization of 2.5. An example of commercially available self-condensing alkylated triazine resin, having both high imino content and methylol functionality is a partially methylated melamine-formaldehyde resin having 3.6 units of combined formaldehyde and 2.0 units of methyl groups per unit of melamine (MF3.6Me2.0), 38 mole% of NH, 40 mole% of methyl, 22 mole% of methylol and a degree of polymerization of 1.8. As noted above, the self-condensable alkylated triazine resins of this invention, which have a high imino content and methylol functionality, can be oligoeric. Such oligomers can be represented by the formula: wherein p is at 10, methylene or the radical -CH2OCH2-, and Z and R are described as above. In general, the self-condensing alkylated triazine resins of this invention are mixtures of monomers and oligomers having a degree of polymerization, ie the average number of triazine units per molecule, of less than 3.0. Typically, the degree of polymerization of the triazine resins of this invention ranges from about 1.5 to about 3.0. These self-condensable alkylated triazine resins having a high content of imino and / or methylol functionality are used as additives promoting adhesion in the present invention, by addition to vulcanizable rubber compositions, in amounts that are in the range from near 0.2 to 10 parts by weight per 100 parts of rubber (hereinafter "phr"). However, any amount of the self-condensable alkylated triazine resin having a high content of imino and / or methylol functionality that gives the vulcanized rubber composition the desired rubbery and rubbery tire adhesion properties can be used. . The self-condensable alkylated triazines can be employed in the vulcanizable compositions of this invention in the form of liquids, solids or as dry powder on a support. Preferably, the self-condensable alkylated triazine resin having a high content of imino and / or methylol functionality is absorbed onto a support selected from the group consisting of silica, calcium silicate or the like. In general, a quantity of resin is mixed with the support in a ratio that provides a dry fluid powder, for example, 70% by weight of resin at 30% by weight of support. The self-condensed alkylated triazine resins having a high content of imino and / or methylol functionality can be mixed with a support by heating the resin at a temperature in the range from about 50 ° C to about 75 ° C, and loading Slowly heat the heated resin to a Hobart mixer containing the support, while mixing at low speed. The mixture is then stirred for an additional 5 or 10 minutes. If the resin contains a solvent, then the mixture can be dried in an oven at about 50 ° C. The silica-based supports are commercially available under the trade names MICROC? L '"- E or HISILMR SC-72 from Johns Manville (Denver, Colorado) and PPG Industries (Pittsburgh, Pennsylvania), respectively.Usually, if a support is used, the resin is present in an amount of about 55 to about 85, more preferably about 65 to about 75 percent by weight of the combined resin and support The main components of the vulcanizable rubber compositions comprise rubber, which can be natural rubber or synthetic rubber, or a mixture of natural and synthetic rubbers, and a vulcanizing agent such as Sulfur such as copolymers of butadiene-styrene, polyisoprene, polybutadiene, polychloroprene, nitrile and ethylene-propylene copolymers, terpolyols, acrylo- and fluoro-elastomer rubbers, copolymer rubbers can be used. block, and the like. Other conventional additives for rubber compositions may be included in the rubber compositions of the present invention, such as carbon black, silica, zinc oxide, stearic acid, antioxidants, vulcanization accelerators, and the like in preferred rubber compositions. according to the present invention. A cobalt salt can also be included as a promoter for tire wire adhesion, preferably used in the ratio of about 0.5 to 1.5 phr. The high adhesion-promoting alkylated additives used in this invention can be used in rubber compositions also containing hydroxymethylmelamines or alkoxymethylmelamines or the like, but in a substantial absence of resorcinol or its equivalents. The equivalents of resorcinol are compounds that can be used in place of resorcinol as methylene acceptors in rubber compositions. Some equivalents of resorcinol are described, for example, in the U.S. Patent. No. 4,605,696. A typical vulcanizable rubber finish coating formulation for wire of the prior art, and typical ranges of the components of such formulations are set forth below: Ingredients Intervals (phr) Natural Rubber 80.0-100.0 Cis Butadiene Rubber 0.0-20.0 Carbon Black 55.0-65.0 Silica 0-15.0 Zinc Oxide 5.0-10.0 Stearic Acid 0.5-2.0 Antidegradant (TMQ, 6PPD) l 1.0-2.0 Naphthenic Oil 5.0-10.0 Accelerator ( DCBS, TBBS, CBS) 2 0.5-1.0 Insoluble Sulfur 4.0-7.0 HMMM3 3.0-7.0 Resorcinol 2.0-6.0 Cobalt Naphthenate (10.5% Co) 1.0-2.0 TMQ = 2, 2, 4-trimethyl-1,2-dihydroquinoline polymerized 6PPD = N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine DCBS = Benzothiazil-2-dicyclohexyl sulfenamide TBBS = Benzothiazil-2 t-butyl sulfenamide CBS = Benzothiazil-2-cyclohexyl sulfenamide HMMM = Hexametoxymethylmelamine The hexametoxymethylmelamine of the vulcanizable rubber finish coating formulations for wire of the prior art described above can be replaced or combined with self-condensing alkylated triazine resins having a high content of imino and / or methylol functionality, and the resorcinol removed to provide the vulcanizable rubber composition of this invention. The self-condensable alkylated triazine resins having a high content of imino and / methylol functionality employed in this invention can be added to rubber compositions by conventional means and methods for the addition of melamine additives in rubber compositions, such as for hydroxymethylmelamines or methoxymethylmelamines. A well-known method for mixing rubber compounds in mixing in a Banbury mixer. In a typical method, additives that are not reactive in the rubber are first mixed at temperatures up to about 140 ° C in the Banbury mixer. The vulcanization agents, accelerators and adhesion promoters are added in a second mixing step, at temperatures from about 90 ° to 100 ° C. Such preparation methods are well within the knowledge of those skilled in the art. The following Example is proposed as an illustration of certain preferred embodiments of the invention, and no limitation of the invention is implied. EXAMPLE 1 A vulcanizable rubber composition was formulated for preliminary coating of tire threads, which contained an alkylated triazine resin with high imino content, and was substantially free of resorcinol, preparing the composition designated "A" in the table below. A comparative formulation with resorcinol was prepared, illustrated below for composition "B". A (phr) B (phr) C Coommppuueessttoo BBaassee Without Resorcinol With resorcinol Natural Rubber 100 100 Carbon Black 55 55 Zinc Oxide 8 8 Stearic Acid 1.2 1.2 TMQ1 3.5 3.5 6PPD ¿0.25 0.25 QBTS3 .70 .70 Insoluble Sulfur 4.69 4.69 HMMM4 3.00 Resorcinol (100%) ___ 2.00 MF resin with high5 4.0 imino content Cobalt naphthenate (10% Co) 1.50 1.50 = 2,2,4-trimethyl-1,2-dihydroquinoline, polystyrated = N- (1,3-dimethylbutyl) -N '-phenyl-p-phenylenediamine 3 = Benzothiazyl-2-sulfen morpholide "* = Hexametoxymethylmelamine"' = Melamine-alkylated formaldehyde resin (high imino type) Typical Curing Conditions: 10-20 minutes at 149-160 ° C C (300-320 ° F). Rheological Characteristics of Curing for Auto-Condensable Triazines Rendered that Have a Content Functionality Imino and Methyl Versus Versus a Totally Rendered Triazine Resin The curing characteristics of (i) a melamine-formaldehyde resin with high imino content (MF) were tested .Me3.3), which had 22 mol% NH, 66 mol% methylation, 12 mol% methylol and a degree of polymerization of 1.75, (ii) a partially methylated melamine-formaldehyde resin having a functionality content imino and methylol (MF3.eMe3.o), which had 38 mol% NH, 40 mol% methylation, 22 mol% methylol and a degree of polymerization 1.8, and (iii) a highly methylated melamine formaldehyde resin (MF5.3Me5.o), which had 94.2 molar% of methylation, 5.8 molar% of methylol and a degree of polymerization of 1.75., generating a rheological curing profile, that is, dynamic viscosity? * versus temperature, for each resin. The curing profiles were generated under the following conditions: Instrument: RMS 605 / TC2000 transducer Slope of 3 degrees C / minute temperature Angular frequency 10 rad / second Parallel plates: 7.9 mm dia. Upper part Bronze 25.0 mm dia. Bottom Opening 1.0 mm The curing initiation temperature deduced from the profile data for the partially methylated melamine-formaldehyde resin having an imino and methylol (ii) functionality content was 147 ± 5 ° C, for the resin of melamine-formaldehyde with high imino content (i) was 160 ± 5 ° C, and for the highly methylated melamine-formaldehyde resin (iii) it was 317 ± 5 ° C. Rheological Characteristics of Curing for a Triazine Resin Fully Resorcinol Mixed Alkylate Comparatively, curing characteristics were measured for a mixture of a highly alkylated melamine-formaldehyde resin ((MFßMßs?), Which had 97.6 molar% methylation, 2.4 molar% methylol and a degree of polymerization of 1.35) and resorcinol, generating a rheological profile of curing, measuring the dynamic viscosity? * At 10 radians per second, 50% maximum elongation and a temperature gradient of 3 ° C per minute, with a configuration of the rheometer in the parallel plates of 50 mm at the bottom and 25 mm at the top. The rheological curing profile for resin containing resorcinol exhibited a curing initiation temperature of 140 ° C. This rheological data illustrates that a self-condensing alkylated triazine resin having a high content of imino functionality, or one having functionality imino and methyl advantageously provides curing properties similar to those of a highly methylated melamine-formaldehyde resin mixed with resorcinol. EXAMPLE 2 A high imine content melamine-formaldehyde resin (MF4.4Me3.3), which had 22 mole% NH, 66 mole% methylation, 12 mole% methylol, was heated to about 50-55 ° C. and a degree of polymerization of 1.75 in about 10% iso-butanol (561 grams). A silica substrate (200 grams) of HISIL "* SC-72 PPG Industries, Pittsburgh, Pennsylvania) was charged to the Hobart mixer.

Mixing was started at low speed, and the resin was slowly added to the substrate, for a period of time of 5 to 10 minutes. After the loading was completed, the mixture was stirred for an additional 5 to 10 minutes, followed by drying at 50 ° C in a vacuum oven, to provide the melamine-formaldehyde resin with high imine content (73.7%) on a silica support (26.3%). This supported resin was then used in a vulcanizable rubber composition, in a manner similar to that of Example 1, composition A. Other variations and modifications of this invention will be obvious to those skilled in the art. This invention is not limited, except by or set forth in the following claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having been described - the invention as above, property is claimed as contained in the following:

Claims (10)

1. REGVINDICATIONS 1. A vulcanizable rubber composition comprising (a) an uncured rubber, (b) a triazine resin additive, and (c) a vulcanizing agent, characterized in that: (1) the triazine resin additive is a dry fluid powder comprising a triazine resin absorbed on a solid support, the triazine resin is selected from the group consisting of: (i) a self-condensable alkylated triazine resin, which has a high content of imino functionality and / or methylol, represented by the formula (I): (ii) an oligomer of (i), and (iii) a mixture of (i) and (ii), wherein Z is selected from the group consisting of -N (R) (CH2OR;), aryl having 6 to 10 carbon atoms, alkyl having from 1 to 20 carbon atoms, and an acetyl group, each R is independently selected from the group consisting of hydrogen and -CH.OR1, and each R1 is independently selected from the group consisting of hydrogen and an alkyl group having from 1 to 12 carbon atoms, provided that at least one R is hydrogen or -CH 2 OH, and at least one R 1 is an alkyl group having from 1 to 12 carbon atoms; and (2) the vulcanizable rubber composition is substantially free of methylene acceptor co-reactants.
2. 2. The vulcanizable rubber composition according to claim 1, characterized in that at least two R groups are hydrogen or -CH2OH. 3. The vulcanizable rubber composition according to claim 1, characterized in that the triazine resin has a degree of polymerization in the range from about 1.5 to about
3. 3.0.
4. 4. The vulcanizable rubber composition according to claim 1, characterized in that Z is N (R) (CH2ORx).
5. 5. The vulcanizable rubber composition according to claim 4, characterized in that at least two R groups are hydrogen or -CH2OH.
6. 6. The vulcanizable rubber composition according to claim 4, characterized in that the triazine resin has a degree of polymerization in the range from about 1.5 to about 3.0. The vulcanizable rubber composition according to claim 1, characterized in that the triazine resin is present in amounts in the range from about 0.2 to about 10 parts by weight per 100 parts by weight of rubber. 8. The vulcanizable rubber composition according to claim 1, characterized further by comprising a cobalt salt. 9. The vulcanizable rubber composition according to claim 1, characterized in that the solid support is selected from the group consisting of silica, calcium silicate and mixtures thereof. 10. A vulcanized rubber, characterized in that it is obtained from the vulcanizable rubber composition according to any of claims 1-9.