rubber composition

Abstract

The present invention provides a rubber composition that allows for better kneading / incorporation of phenolic resin into the rubber mixture, and in which the phenolic resin exhibits good compatibility with the rubber components. [Solution] A composition comprising at least one base polymer and at least one benzyl alkylphenol novolac resin, wherein a) the base polymer is selected from at least one rubber component, and b) the benzyl alkylphenol novolac resin is produced by a reaction between an alkylphenol novolac resin and a benzylating agent.

Description

Technical Field

[0001] The present invention relates to a composition comprising at least one base polymer and at least one benzylated alkylphenol resin.

Background Art

[0002] In the production of many rubber articles, it is necessary for individual members to have good green tack (Konfektionsklebrigkeit) in the unvulcanized state so that the member stays in the desired position until vulcanization. In order to enhance green tack, it has been conventionally known to add a so-called tackifying resin to a rubber mixture. Typical tackifying resins used in the rubber industry are, for example, coumarone-indene resins, petroleum resins, terpene-phenol resins, rosin resins or phenol resins.

[0003] Phenol resins are known in the production of rubber products, particularly tire components. In addition to an increase in green tack (for example, Patent Document 1: US3,962,156), phenol resins cause curing in the final product by forming their own network structure. They can also be used as crosslinking agents in certain types of rubber, such as butyl rubber (Patent Document 2: DE1669863A1). When a rubber mixture is used for adhesion to a fiber or metal reinforcing carrier, a phenol resin can increase the bond to the reinforcing carrier (for example, Patent Document 3: DE3033711A1).

[0004] In the use of phenol resins, it is important to enhance the compatibility of the phenol resin with the rubber component in order to obtain both processing technical advantages (adhesiveness) and improvements in the properties of the vulcanized product.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] Therefore, the object of the present invention is to provide a rubber composition that results in better kneading / incorporation of phenolic resin into the rubber mixture and in which the phenolic resin has good compatibility with the rubber components, which means good green tack and excellent processability of the rubber composition. [Means for solving the problem]

[0007] The aforementioned problem is that in the present invention, the composition contains at least one base polymer and at least one benzyl alkylphenol-novolac resin, a) The base polymer is selected from at least one rubber component, b) The benzylated alkylphenol-novolac resin is produced by the reaction of the alkylphenol-novolac resin with a benzylate agent. This will resolve the issue.

[0008] Surprisingly, it has been found that the use of benzylated alkylphenol-novolac resin can improve compatibility with base polymers made of at least one rubber component. This effect may be due to the reduction of the resin's polarity, and therefore improved bonding to non-polar rubber components. This results in a similarly high level of green tack compared to conventional rubber mixtures, thereby making the compositions of the present invention particularly suitable for the manufacture of tire components, such as treads or sidewalls. Yet another reason for the very good green tack is that the benzylated alkylphenol-novolac resin can be completely melted in the rubber mixture during the mixing process because the resin has a lower softening point than, for example, non-benzylated alkylphenol-novolac resins.

[0009] Aside from the low melting range of benzylated alkylphenol novolac resins, it was surprisingly discovered that the modification of alkylphenol resins by the benzylation reaction also reduces the melt viscosity of the resin. Since the molar mass increases due to the benzylation reaction, which usually results in a higher softening range and higher melt viscosity, both the decrease in melting range and the decrease in melt viscosity were unexpected. Reducing the melting range and decreasing melt viscosity leads to faster melting behavior and therefore faster distribution of benzylated alkylphenol novolac resins in rubber mixtures. Furthermore, the lower melting range of benzylated alkylphenol novolac resins allows for lower mixer and roller temperatures, which can contribute to energy savings. Similarly, potentially environmentally harmful emissions in the mixing process can be reduced by lowering the mixing temperature.

[0010] The compositions of the present invention contain at least one rubber component as a base polymer. The rubber component is preferably selected from the group consisting of natural and synthetic polyisoprene, styrene-butadiene copolymer, particularly emulsion-polymerized styrene-butadiene rubber and solution-polymerized styrene-butadiene rubber, polybutadiene, polyisobutylene, isobutene-isoprene copolymer, acrylonitrile-butadiene copolymer and polyoctenamer, propylene-ethylene copolymer, ethylene-propylene-diene copolymer, halobutyl rubber, chloroprene rubber, isoprene-butadiene copolymer and / or styrene-isoprene-butadiene copolymer.

[0011] These rubber components may be bonded and / or modified and / or functionalized, are known from the prior art, can be well processed into the rubber composition of the present invention, and can impart good properties to vulcanization products, particularly tire components.

[0012] Other possible rubber components, depending on the application of the vulcanized product, may include, for example, fluororubber, chlorosulfonated polyethylene (CSM), and / or ethylene-vinyl acetate copolymer (EVM).

[0013] It is particularly preferable to use emulsion-polymerized styrene-butadiene copolymer (ESBR) and / or solution-polymerized styrene-butadiene copolymer (SSBR) as the rubber component. Types known from the prior art, obtained by copolymerization of styrene and 1,3-butadiene in an aqueous emulsion, can be used to produce ESBR. SSBR can be produced, for example, using lithium alkyl in an organic solvent. A mixture of ESBR and SSBR can also be used as the rubber component for the composition according to the present invention. The styrene-butadiene copolymer may be bonded or end-group modified.

[0014] Furthermore, it is preferable that the rubber component be selected from polyisoprene (IR, NR). This may be either cis-1,4-polyisoprene or 3,4-polyisoprene. It is preferable to use cis-1,4-polyisoprene having a cis-1,4 content of more than 90% by weight. Synthetically, such polyisoprene can be obtained by stereospecific polymerization in solution using a Ziegler-Natta catalyst, or by using finely powdered lithium alkyl. Natural rubber (NR) is cis-1,4 polyisoprene with a cis-1,4 content exceeding 99% by weight.

[0015] Advantageously, the compositions according to the present invention have polybutadiene (BR) as a rubber component, which may be either cis-1,4-polybutadiene or vinyl-polybutadiene (vinyl content of 10 to 90% by weight). The use of cis-1,4-polybutadiene having a cis-1,4 content of more than 90% by weight is preferred, which can be produced, for example, by solution polymerization in the presence of a rare-earth type catalyst.

[0016] The composition according to the present invention further comprises, as another component, at least one benzylated alkylphenol novolac resin, which is obtained by reacting the alkylphenol novolac resin with a benzylate agent.

[0017] In this application, alkylphenol novolac resins are understood to be resins produced by the condensation of at least one alkylphenol with at least one aldehyde, or by the addition of at least one alkylphenol to an unsaturated compound (e.g., alkenes, alkynes, unsaturated resins). However, alkylphenol novolac resins can also be produced using a mixture of alkylphenols and other phenols (e.g., phenols, cresols, bisphenols), where the alkylphenol content in the mixture should be at least 70%. It has been found that in alkylphenol novolac resins produced using an alkylphenol / phenol mixture, the green tack decreases as the proportion of short-chain phenols in the mixture increases.

[0018] Alkylphenols are produced by alkylation of phenolic compounds. The phenolic compounds are preferably selected from the group consisting of unsubstituted and substituted phenols, such as phenols, cresols, brent catechins, hydroquinones, resorcinols, and / or bisphenols, such as bisphenol A and / or bisphenol F and / or cashew nut shell liquid (CNSL).

[0019] Alkylation reactions, including alkylating agents, are known from prior art. Preferably C4-C 12 Alkylphenols (or similar compounds) having alkyl chains (branched or unbranched) are obtained. The corresponding alkyl substituent of the phenol may be positioned in the para or ortho position relative to the OH group, and mixtures of o- and p-alkylphenols (or similar compounds) can also be used. C4~C 12The use of alkylphenols, particularly butylphenol isomers and / or tert-butylphenol (preferably p-tert-butylphenol) and / or butylphenol and / or octylphenol isomers and / or tert-octylphenol (preferably p-tert-octylphenol) and / or octylphenol and / or nonylphenol- and / or dodecylphenol isomers, is preferred because these products can be easily manufactured and are therefore readily available commercially.

[0020] Alkylphenol novolac resins are produced by the condensation of at least one alkylphenol with at least one aldehyde, preferably formaldehyde, p-formaldehyde, acetaldehyde, furfurylaldehyde, or benzaldehyde. The alkylphenol is used in a molar ratio of 1:0.2 to 1:>1.0, preferably 1:0.5 to 1:0.9, relative to the aldehyde, and an acidic catalyst is used. The aforementioned specific molar ratios yield a solid alkylphenol novolac resin with a softening point above 60°C, which has good handling properties. As acidic catalysts, generally, for example, oxalic acid or p-toluenesulfonic acid, benzenesulfonic acid, hydrochloric acid, sulfuric acid, phenolsulfonic acid and metal salts, or mixtures of two or more of these are used. This reaction is known to those skilled in the art. Furthermore, alkylphenol novolac resins can be produced by reacting alkylphenols with unsaturated compounds, such as alkenes or alkynes (e.g., acetylene), or unsaturated resins (e.g., terpene resins) by addition (e.g., S. Schroeter: Klebharze, Hinterwaldner Verlag Muenchen, 1994, page 137, or A, Gardziella, LA Pilato, A. Knop: Phenolic Resins, 2. Edition, Springer Verlag, 1999, page 22).

[0021] An alkylphenol novolak resin having an alkyl group on the phenolic ring, preferably at the o- and / or p-position, and preferably having a branched and / or unbranched alkyl group having up to 12 carbon atoms can be formed.

[0022] The production of benzylated alkylphenol novolak resin is carried out by reacting an alkylphenol novolak resin with a benzylating agent preferably selected from benzyl alcohol, benzyl chloride, benzyl bromide, benzyl ether and / or their derivatives (for example, the molar ratio of alkylphenol novolak resin:benzylating agent is 1:1.2 to 1:2.4) in an acidic medium. The alkylphenol-novolak resin is heated to about 160 °C together with a benzylating agent, for example, benzyl alcohol. Then, 0.1 to 1% of a suitable acid is added (oxalic acid, p-toluenesulfonic acid, benzenesulfonic acid, hydrochloric acid, sulfuric acid, phenolsulfonic acid, phosphoric acid, metal salts, mixtures of two or more of these). The water produced by the reaction is removed by distillation. When most of the benzyl alcohol has reacted, the reaction is complete.

[0023] However, the alkylphenol novolak resin can also exist as a melt / fusion. The addition of the benzylating agent can also be carried out over a longer period.

[0024] An exemplary formula for the reaction of an alkylphenol novolak resin with benzyl alcohol is schematically shown here:

[0025]

Chemical formula

[0026] The compositions of the present invention may also further contain, in conventional concentrations, other conventional additives, such as yet another resin, processing aid, filler, antioxidant, activator, softener, vulcanization aid, and / or vulcanization accelerator.

[0027] Further resins include, for example, hydrocarbon resins based on terpene phenols, polyterpenes (corophonium), α-limonene, β-pinene, indene-coumarone resins, and other phenolic resins or pentaerythritol esters, with concentrations such as 0 to 20 phr. To achieve better compatibility with rubber components, phenol novolacs using hexamethylenetetramine (optionally modified with approximately 20% cashew nut shell liquid or tall oil) are also suitable as reinforcing resins.

[0028] To ensure optimal processing of the mixture for each application field and to obtain suitable vulcanization products with desired properties, conventional chemicals such as stearic acid, factor, dispersants, process oils, waxes, fats, or metal salts can also be used as processing aids.

[0029] The compositions of the present invention generally contain fillers that have a reinforcing effect in rubber mixtures and / or vulcanization products, such as carbon black, silica, aluminosilicate, chalk, starch, magnesium oxide, titanium dioxide, or rubber gel. The amount of filler is preferably 0.1 phr to 200 phr.

[0030] The use of carbon black and / or silica (preferably in amounts of 0.1 phr to 200 phr) is particularly preferred. The carbon black used is the kind commonly used in rubber mixtures. Preferred silica is, for example, 35 to 350 m 2 This is finely ground precipitated silica having a nitrogen surface area (BET surface area) (according to DIN 66131 and 66132). Such silica provides particularly good physical properties to vulcanized products, for example, in rubber mixtures for tire treads. Here, it is advantageous to add a coupling agent, such as silane, as an additive to the composition of the present invention in order to improve processability and bond the silica to the rubber component.

[0031] Examples of anti-aging agents include N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), and other substances known from, for example, J. Schnetger, Lexikon der Kautschuktechnik, 2. Auflage, Huethig Buch Verlag, Heidelberg, 1991, pp. 42-48.

[0032] Furthermore, the rubber mixture contains common activators. These activators may be zinc oxide and fatty acids, or zinc soap based on zinc oxide and fatty acids. Alternatively, a mixture of zinc oxide and metal acrylate and / or metal methacrylate can be used. These are preferably used in amounts of 0.1 to 3.0 phr of zinc oxide and 0.1 to 3.0 phr of metal acrylate and / or metal methacrylate.

[0033] Preferably, mineral oil is used as a softening agent, and alternatively or additionally, a liquid polymer suitable as a substitute for mineral oil as a softening agent may also be used. The softening agent, preferably mineral oil, is used in an amount of 1 to 160 phr, for example 5 to 75 phr, and particularly 10 to 60 phr. The liquid polymer, for example liquid polybutadiene, is used in a suitable amount of 0 to 160 phr, but at least 0.1 phr, for example 5 to 75 phr, and particularly 10 to 60 phr.

[0034] Vulcanization is carried out in the presence of sulfur or a sulfur donor, some of which also act as vulcanization accelerators. The sulfur or sulfur donor is added to the rubber mixture in the final mixing step in amounts commonly used by those skilled in the art (0.4 to 4 phr, preferably 1.5 to 2.5 phr of sulfur).

[0035] However, other vulcanization systems, such as those based on peroxides, are also possible.

[0036] Furthermore, the rubber mixture may contain, in customary amounts, other vulcanization-influencing substances, such as vulcanization accelerators, vulcanization retarders, and vulcanization activators, to control the time and / or temperature required for vulcanization and to improve the properties of the vulcanized product. Here, the vulcanization accelerator can be selected from, for example, the following group of accelerators: thiazole accelerators, e.g., 2-mercaptobenzothiazole; sulfenamide accelerators, e.g., benzothiadyl-2-cyclohexylsulfenamide (CBS); guanidine accelerators, e.g., N,N'-diphenylguanidine (DPG); dithiocarbamate accelerators, e.g., zinc dibenzyldithiocarbamate, disulfide. The accelerators can also be used in combination with each other to produce synergistic effects.

[0037] Depending on the application, the composition of the present invention can be modified. Therefore, both the rubber component and the benzylated alkylphenol novolac resin can be selected to optimize the properties of the vulcanization product.

[0038] For example, with respect to tire components, such as tread mixtures or sidewall mixtures, the composition may contain the following components: a) BR up to 100 phr, preferably 10-80 phr b) NR up to 100 phr, preferably 10-80 phr c) ESBR and / or SSBR up to 100 phr, preferably 10 to 100 phr d) 0.1 to 30 phr of benzyl alkylphenol novolac resin, preferably 1 to 10 phr, more preferably 2 to 6 phr e) Yet another additive ranging from 0.1 to 400 phr.

[0039] The composition of the present invention is manufactured in two steps using conventional methods. Generally, a base mixture containing all components except the vulcanizing system (sulfur and vulcanizing-inducing substances) is first prepared in one or more mixing steps, for example, using a meshing internal mixer. Subsequently, the vulcanizing system is added at a lower temperature, thereby preparing and manufacturing the final mixture on rollers. The mixture can be discharged, cooled, and stored for several days until final vulcanization.

[0040] When the prepared mixture is to be used as the sidewall or tread for a tire, it is applied to a pre-manufactured tire blank in a known manner as a blank.

[0041] However, generally speaking, the compositions of the present invention can also be used for other tire components.

[0042] Furthermore, the compositions according to the present invention can be used for a number of other application areas of crosslinked rubber products, for example, for the manufacture of industrial rubber products, such as damping elements, rubber sleeves, drive belts, seals, bellows and / or conveyor belts. The compositions according to the present invention can also be used in layers that must have good adhesion to fabrics or meshes to which metal and / or fiber-reinforced carriers are introduced. [Examples]

[0043] The present invention will be described in more detail based on the examples.

[0044] a) Production of alkylphenol novolac resins: Alkylphenol novolac resins can be manufactured according to known methods. Alkylphenols (or mixtures of alkylphenols, optionally containing phenols) are optionally melted, an acidic catalyst (e.g., oxalic acid, p-toluenesulfonic acid, dodecylphenolsulfonic acid) is added, and formaldehyde is added by metering over 1 hour at approximately 100°C. The reaction is then carried out for 1 to 3 hours until the formaldehyde content is reduced to less than 1%. The mixture is then distilled to 160°C under standard pressure and then to 170–220°C under vacuum. The molten resin is poured out and cooled.

[0045] As shown in Table 3, p-tert-butylphenol, p-tert-octylphenol, and isononylphenol were used as alkylphenols, and the corresponding alkylphenol novolac resins were produced using the molar ratio (MV) alkylphenol:formaldehyde described (Table 3: Compounds I, III, V, VII).

[0046] b) Production of benzylated alkylphenol novolac resin: a) Mix the alkylphenol novolac prepared in the above with a corresponding amount of benzyl alcohol (molar ratio: alkylphenol novolac resin to benzyl alcohol 1:1.8) and heat to 140-160°C. Add sulfonic acid or sulfuric acid. React at 140-160°C for approximately 2-6 hours until the benzyl alcohol content is significantly reduced. The formed water can be removed at the same time if necessary. Subsequently, remove the water by vacuum distillation to 170-220°C. Pour out the resin molten / melt and allow to cool.

[0047] Compounds II, IV, VI, and VIII were prepared as shown in Table 3.

[0048] c) Composition and manufacture of the present invention's composition for tire sidewall mixtures

[0049] [Table 1] Mixed order: 0-0.5 minutes Rubber component 0.5-1.5 minutes 2 / 3 carbon black, zinc oxide, resin, wax, 6PPD, TMQ 1.5-3.0 minutes 1 / 3 carbon black and softener 5.0-6.0 minutes: Increase rotation speed to 70 rpm and reach target temperature of 120°C. The components were mixed together in a preheated kneading device at a rotor speed of 40 rpm for 3 minutes. Subsequently, the rotor speed was increased to 70 rpm, and the mixture was discharged at a temperature of 120°C. The mixture was homogenized in a rolling mill, cooled to 60°C, and the following components were mixed in.

[0050] [Table 2] d) Composition and manufacture of the composition of the present invention for passenger car tread mixtures

[0051] [Table 3] Mixed order: 0-1.0 minutes Rubber component 1.0-4.0 min 2 / 3 carbon black, zinc oxide, resin, 6PPD, TMQ 4.0-6.5 minutes 1 / 3 carbon black and softener 5.0-6.5 minutes: Increase the rotation speed to 70 rpm and reach the target temperature of 120°C. The components were mixed together in a preheated kneading device at a rotor speed of 40 rpm for 3 minutes. Subsequently, the rotor speed was increased to 70 rpm, and the mixture was discharged at a temperature of 120°C. The mixture was homogenized in a rolling mill, cooled to 60°C, and the following components were mixed in.

[0052] [Table 4] The benzylated or non-benzylated alkylphenol novolac resins produced according to a) and b), and the compositions produced according to c) and d), were subjected to various tests (see Table 3) under the following conditions: a) Melt viscosity: ISO 2884-1 b) Melting range capillary method [°C], R&K method [°C]: DIN EN ISO 3146, DIN ISO 4625 c) OH value [mg KOH / g]: DIN 53240 d) Moisture content [%]: Karl Fischer method, DIN 51777 e) Measurement of free alkylphenols [%] by gas chromatography f) Adhesion measurement The tackiness of the mixture was tested against itself using a Hock tester. For this purpose, the mixture was spread onto thin sheets of rubber and tested after 1 day or 5 days of storage, respectively. The tests were conducted at room temperature with a contact force of 50 N and a pressure duration of 10 seconds. Measurements were taken in five layers.

[0053] [Table 5] The results in Table 3 show that the melt viscosity and melt range of the benzylated alkylphenol novolac resins II, IV, VI, and VIII of the present invention, measured at both 150°C and 175°C, are lower than those of the non-benzylated alkylphenol novolac resins I, III, V, and VII. This effect was surprising to those skilled in the art, as the molar mass increases with the benzylation reaction, and therefore a higher viscosity and melt / melt range is expected.

[0054] As mentioned earlier, a reduction in melt viscosity and melting range has a positive effect on the processability of the mixture. This results in a more time- and energy-saving supply of rubber mixtures, and at the same time, the service life of mixing equipment and tools can be increased. The mixture can be prepared / manufactured at lower temperatures, thereby reducing the emission of harmful gases, which enables the production of the composition of the present invention, which is also environmentally and worker-friendly.

[0055] DMA measurement was used to determine the glass transition temperature (T) at 0°C and 60°C. G The values ​​() and tanδ were determined, and this shows that the wet sliding properties (Nassrutscheigenschaften) and rolling resistance of the vulcanized composition containing the benzylated alkylphenol novolac resin are almost identical to those of the composition containing the non-benzylated alkylphenol novolac resin.

Claims

1. A composition comprising at least one base polymer and at least one benzyl alkylphenol novolac resin, a) The base polymer is selected from at least one rubber component, b) The benzylated alkylphenol novolac resin is produced by the reaction of an alkylphenol novolac resin with a benzylating agent. The aforementioned composition.

2. The composition according to claim 1, characterized in that the rubber component is selected from the group consisting of natural and synthetic polyisoprene, styrene-butadiene copolymer, polybutadiene, polyisobutylene, isobutene-isoprene copolymer, acrylonitrile-butadiene copolymer and polyoctenamer, propylene-ethylene copolymer, ethylene-propylene-diene copolymer, halobutyl rubber, chloroprene rubber, isoprene-butadiene copolymer and / or styrene-isoprene-butadiene copolymer.

3. The composition according to claim 1 or 2, characterized in that the benzylated alkylphenol novolac resin is produced by benzylation of an alkylphenol aldehyde resin.

4. The composition according to claim 1 or 2, characterized in that the benzylated alkylphenol novolac resin is produced by benzylation of an alkylphenol acetylene resin.

5. The benzyl alkylphenol novolac resin is C ４ ~C １２ The composition according to any one of claims 1 to 4, characterized in that it is produced using alkylphenol.

6. The composition according to claim 5, characterized in that the alkylphenol used is a butylphenol isomer and / or tert-butylphenol and / or butylphenol and / or octylphenol isomer and / or tert-octylphenol and / or octylphenol and / or nonylphenol- and / or dodecylphenol isomer.

7. The composition according to any one of claims 1 to 6, further comprising another additive, such as yet another resin, processing aid, filler, antioxidant, activator, softener, vulcanization aid and / or vulcanization accelerator.

8. The composition according to any one of claims 1 to 7, characterized by containing 0.1 to 30 phr of benzyl alkylphenol novolac resin.

9. The composition according to claim 8, characterized by containing 1 to 10 phr of benzyl alkylphenol novolac resin.

10. The composition according to claim 8, characterized by containing 1 to 10 phr of benzyl alkylphenol novolac resin.

11. The composition according to any one of claims 1 to 10, having the following components: a) BR up to 100 phr, preferably 10 to 80 phr, b) NR up to 100 phr, preferably 10 to 80 phr, c) ESBR and / or SSBR up to 100 phr, preferably 10 to 100 phr. d) A benzyl alkylphenol novolac resin in a concentration of 0.1 to 30 phr, preferably 1 to 10 phr, and more preferably 2 to 6 phr, and e) Another additive in the range of 0.1 to 400 phr.

12. Use of the composition according to any one of claims 1 to 11 for producing a crosslinked rubber product.

13. Use of the composition according to claim 12 for the manufacture of tire components, particularly tire sidewalls and tire treads.

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