JP2003522065A - Solid silica coupling agent composite in silica rubber - Google Patents

Abstract

  (57) [Summary] Silica-containing rubber compositions, such as silica-containing rubber compositions utilized in various tire components, contain a solid silica coupling agent binder complex.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION

The present invention relates to a silica coupling agent composite containing a solid binder used in a rubber composition containing silica.
tcomposite). The use of the solid silica coupling agent complex is easy to handle, such as minimizing agglomeration, enhanced dispersion, promotion of silica-rubber adhesion, and ease of complex identification. Have advantages.

[0002]

BACKGROUND OF THE INVENTION

Coupling agents are often utilized to link the toughening silica to polymer chains, such as sulfur vulcanizable rubber chains. In recent years, organosilanes have become a well-known coupling agent used in rubber compositions. One component of the coupling agent reacts with the surface of the silica and the other component reacts with the rubber, thereby linking or bridging them via covalent bonds.

Organosilanes, which have recently been used commercially, pose many problems in their utility. Usually, organosilanes such as bis (3-triethoxysilylpropyl) tetrasulfide are in liquid form. Examples of such silanes include Degus
SI-69 and Witco (W sold by sa Corporation
A1289 sold by Itco). Organosilanes are "supported" (organic silanes are mixed in various proportions with carbon black such as X50-S available from Degussa Corp.
Also available as "grade"), often these materials are cumbersome to handle. Accurate measurements are difficult to achieve, both for liquid forms and for supported brands, and often equipment, containers Waste matters due to material sticking to etc. Organosilane supported brands tend to be dusty, difficult to disperse and look like other types of carbon black. Dust resulting from handling can be undesirable.

[0004]

SUMMARY OF THE INVENTION

The present invention relates to a rubber composition containing silica and a composite containing a silica coupling agent and a binder. Solid binders such as waxes and optionally polyolefins are preferred. The use of a solid silica coupling agent composite is desirable in various tire components, such as treads, when it contains silica. The composites of the present invention melt completely into compositions such as rubber compositions and produce improved dispersion. Such complexes are clean, environmentally friendly and easily identifiable.

[0005]

Aspects of the invention

An important aspect of the present invention is the addition of the generally solid composite to the silica reinforced rubber composition. The composite comprises a substantially homogeneous mixture of silica coupling agent and binder. Generally, any solid shape can be utilized, such as pellets, cubes, spheres, etc., but pellets are preferred.

In general, functional groups or reactive groups capable of reacting with silica, and other functional groups capable of reacting with rubbers, especially sulfur vulcanizable rubbers containing unsaturated carbon-carbon bonds. Alternatively, any conventional silica coupling agent can be utilized including a silica coupling agent that also has a reactive group. Thus, the silica coupling agent acts as a connecting bridge between silica and rubber. Suitable functional groups include amino, vinyl, epoxy, mercapto, chloro, bromo and iodo, methacryl and methacryl.
It includes glycidoxyl, nitroso, imide, octyl, oligomer, ureido or polysulfide groups and the like.

[0007]   Preferred coupling agents of the present invention have the formula

[0008]

[Chemical 2]

Where n is an integer from 2 to about 7 and k and m are independently 0 (ie absent)
˜3, and R ^{1 to} R ⁶ are independently H, or alkyl having 1 to 12 carbon atoms. Examples of such organic silane coupling agents are 2,2'-bis (trimethoxysilylethyl) disulfide, 3,3'-bis (trimethoxysilylpropyl) disulfide, 3,3'-bis (triethoxysilyl). Propyl) disulfide, 2,2'-bis (triethoxysilylpropyl) disulfide, 2,2'-bis (tripropoxysilylethyl) disulfide, 2,2'-bis (tri-sec-butoxysilylethyl) disulfide, 2 , 2'-bis (tri-t-butoxyethyl) disulfide, 3,3'-bis (triethoxysilylethyltolylene) disulfide, 3,3'-bis (trimethoxysilylethyltolylene) disulfide, 3,3 ′ -Bis (triisopropoxypropyl) disulfide, 3,3′-bis (tri Ctoxypropyl) disulfide, 2,2'-bis (2'-ethylhexoxysilylethyl) disulfide, 2,2'-bis (dimethoxyethoxysilylethyl) disulfide, 3,3'-bis (methoxyethoxypropoxysilylpropyl) ) Disulfide, 3,3'-bis (methoxydimethylsilylpropyl) disulfide, 3,3'-bis (cyclohexoxydimethylsilylpropyl) disulfide, 4,4'-bis (trimethoxysilylbutyl) disulfide 3,3'- Bis (tripropoxysilyl-3-methylpropyl) disulfide, 3,3′-bis (trimethoxysilyl-3-methylpropyl) disulfide, 3,3′-bis (dimethoxymethylsilyl-3-ethylpropyl) disulfide, 3, 3'-bis (trime Xysilyl-2-methylpropyl) disulfide, 3,3'-bis (dimethoxyphenylsilyl-2-methylpropyl) disulfide, 3,3'-bis (trimethoxysilylcyclohexyl) disulfide, 12,12'-bis (trimethoxy Silyldodecyl) disulfide, 12,12'-bis (triethoxysilyldodecyl) disulfide, 18,18'-bis (trimethoxysilyloctadecyl) disulfide, 18,18'-bis (methoxydimethylsilyloctadecyl) disulfide, 2,2 ′ -Bis (trimethoxysilyl-2-methylethyl) disulfide, 2,2′-bis (triethoxysilyl-2-methylethyl) disulfide, 2,2′-bis (tripropoxysilyl-2-methylethyl) disulfide ,
And 2,2′-bis (trioctoxysilyl-2-methylethyl) disulfide,
Includes.

Highly preferred organosilane silica coupling agents are bis (3-triethoxysilylpropyl) tetrasulfide or bis (3-triethoxysilylpropyl)
Includes disulfides or combinations thereof.

Other suitable organosilane coupling agents are methyltriethoxysilane, methyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane,
Vinyl-tris (2-methoxyethoxysilane), vinyltriacetoxysilane,
γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyl-tris- (2-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ- Mercaptopropyltrimethoxysilane, γmercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriethoxysilane, aminoalkylsilicone solution, modified aminoorganosilane, γaminopropyltrimethoxysilane, N- It includes β- (aminoethyl) -γ aminopropyltrimethoxysilane, modified aminoorganosilanes, triaminofunctional silanes and the like.

When a silane-modified elastomer, that is, an elastomer having silane functional groups as part of the polymer is utilized, it is proportionately less due to the presence of the silica coupling agent contained within the elastomer. An amount of the above coupling agent is utilized.

The amount of silica coupling agent, based on 100 parts by weight of silica, is generally about 0.
1 to about 20 parts by weight, desirably about 0.5 to about 15 parts by weight, preferably about 1.0 to
It is about 10 parts by weight. The function of the binder is to act as a carrier for the silica coupling agent. As described herein, the term "binder" comprises all components in the complex except the silica coupling agent. The binder has a higher melting point than the silica coupling agent and gives the composite a solid form at ambient temperature of about 70 ° F (21 ° C).

The binder is a wax (preferred), a thermoplastic polymer, a compatibilizer (compa).
tibilizing agent), wetting agent, fatty acid, ethylene vinyl acetate,
It can be a stabilizer and the like and combinations thereof. Any natural, synthetic or petroleum based wax can be utilized in the binder. Examples include, but are not limited to, paraffin, microcrystalline wax, carnauba wax and beeswax. Microcrystalline wax is preferred.

Any thermoplastic polymer such as polyolefins made from monomers having 2 to 6 carbon atoms can be utilized in the binder of the present invention. Thermoplastic polymers are generally optional and are utilized as a blend with wax or other ingredients. Preferably, the thermoplastic polymer is oxidized polyethylene, which is compatible with the silica coupling agent and the binder component.
help promote lity). The amount of binder is generally about 25 to about 90% by weight, preferably about 28 to about 7% by weight, based on the total weight of silica coupling agent and binder.
It is 5% by weight, preferably about 32 to about 55% by weight. Oxidized polyethylene can be utilized alone, but it is generally utilized as a minor portion in combination with wax.

The binder complex is formed by combining the silica coupling agent and the binder in a liquid phase that allows the components to be blended to form a homogeneous mixture. The mixture is processed by conventional methods into the desired workable form such as pellets, spheres and the like. One such method for making composites is US Pat. No. 5,621,0.
You can find it in No. 32.

The preferred complex utilized in the present invention is that available from Elastchem known as "FE (TESPT) -60". This complex is bis (3-triethoxysilylpropyl) in a binder of wax and oxidized polyethylene.
Contains tetrasulfide. This composite is generally free of mineral filler and carbon black.

The amount of silica coupling agent complex can vary, but is generally about 0.2 to about 30 parts by weight, preferably about 3 parts by weight, based on 100 parts by weight of all silica utilized in the rubber composition. To about 25 parts by weight, preferably about 6 to about 18 parts by weight.

The silica in the rubber composition may generally be any type of silica such as fumed silica, hydrated silica, but is preferably precipitated silica. The advantages of using silica include reduced rolling resistance in tires, and therefore improved gasoline mileage for vehicles. Suitable silicas are generally about 40 to about 600 m ^{2 as} measured using nitrogen gas.
/ G, preferably about 50 to about 300 m ² / g BET surface area. The actual BET method for measuring surface area is the Journal of The American
Chemical Society. Volume60, page304 (19
30). Final particle size of silica (ultimate particle)
le size) is generally from about 0.1 to about 100 nanometers, preferably from about 5 to about 50 nanometers, as measured by electron microscopy. However, smaller or larger particles can be present. The amount of silica is 1 for all tire parts rubber
It is in the range of about 5 to about 100 parts by weight, desirably about 15 to about 80 parts by weight, and preferably about 25 to about 60 parts by weight per 00 parts by weight. Commercially available silicas that can be utilized in the present invention include Hi such as 190, 210, 233, 243, etc.
-Silica commercially available from PPG Industries under the Sil trademark; silica from Lone Poulin, such as Z1165MP and Z165GR; VN
2 and silica such as VN3 and Akzo available from Degussa AG
Includes silica from Chemical.

The rubber composition of the present invention comprises natural rubber, at least one conjugated diene monomer or conjugated diene and one or more vinyl substituted aromatic monomers and optionally ethylene and propylene monomers, or ethylene-propylene and Manufactured from non-conjugated dienes (ie EPDM rubber). Conjugated diene monomer is 4-10 in total
Having 3 carbon atoms, for example, 1,3-butylene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 2,3- Includes dimethyl-1,3-pentadiene, 2-phenyl-1,3-butadiene, and 4,5-diethyl-1,3-octadiene. The one or more vinyl-substituted aromatic monomers have a total of 8 to 12 carbon atoms, such as 1-vinylnaphthalene, 3-methylstyrene (p-methylstyrene).
, 3,5-diethylstyrene and the like, with styrene being preferred. Preferred tread rubber compositions generally include natural rubber (cis-1,4-polyisoprene), synthetic polyisoprene, styrene butadiene rubber, modified styrene butadiene-butadiene rubber, butadiene rubber, modified butadiene rubber, and the like. . Often the rubber is oil extended.

The rubber composition of the present invention, such as the tread, may be compounded by methods and procedures well known in the rubber compounding art and may contain suitable amounts of various conventional additives. For example, carbon black, special conductive carbon black (ex
Tra conductive carbon black), and other types of carbon black, curable aids such as sulfur, sulfur-containing compounds, and the like are utilized.

Vulcanization accelerators that can be used in the present invention include amines, disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates and the like. Other additives are various oils such as aromatic oils, naphthenic oils or paraffinic oils; various antioxidants such as various phenylenediamines; various antiozonants; various aliphatic acids such as Stearic acid; zinc oxide; various waxes such as microcrystalline wax; peptizers, starches and the like. Various fillers such as clays, eg kaolin, clays, etc. can also be utilized.

The rubber composition containing the silica coupling agent composite of the present invention can be utilized in any application where it is desirable to use the silica coupling agent in a form that is easy to handle, compound and weigh. . Thus, specific applications include and are preferably utilized in treads, such as tire treads, tire sidewalls, tire casings, carcass plies sub-treads, and other tire components. . The silica coupling agent composites can also be used in many other applications such as hoses, belts, wire cables, shoe soles and applications where silica reinforced rubber is utilized.

The solid composite of the present invention is a good alternative when compared to liquid or supported brand silica coupling agents. This complex is environmentally friendly. Because it leaves no appreciable residue in the container or handling equipment and therefore a smaller amount of product is discarded. Since it is a solid, stratification
Cation) or loss to the dust collector will not occur. This composite also provides improved batch-to-batch variability and is easily visually distinguishable from blends containing carbon black along with other materials.

[0025]   The following examples illustrate the invention but do not limit it.

EXAMPLES Two examples were prepared utilizing a silicone-containing styrene-butadiene rubber solution,
And EF (tetrasulfide and disulfide forms of this bis (3-triethoxysilylpropyl) produced by Elastochem Inc and containing a binder of wax and oxidized polyethylene, respectively.
Blended with TESPT) -60 and EF (DISS) 60. Example 1 with control
The formulation and physical properties of Nos. 2 and 2 are shown in Table 1.

[0027]

[Table 1]

The control and Example 1 were prepared as follows. The first mixing stage involved adding the polymer, half the carbon black, the silica coupling agent, and all other ingredients except the promoter and sulfur. It was mixed in a Banbury at a temperature of 300 ° F for about 3 minutes. During the second mixing stage, the rest of the carbon black was added and mixed in a Banbury at about 300 ° F for about 2 minutes.

The subsequent remilling step was mixed at a temperature of about 260 ° F. for about 1 minute.

The final mixing stage involved adding all of the accelerator and sulfur to the batch and mixing at a temperature of about 200 ° F. for 1 minute.

The rubber stock is thinned into a preferred (conventional) form (test sample).
Eted out) and cured at 170 ° C. for 15 minutes.

After vulcanizing the samples, the rubber was tested for the viscoelastic properties listed in Table 1. Example 2 had the same formulation as Example 1 except that a disulfide organosilane coupling agent was utilized. This allowed the compounding formulation to be compounded in the first stage at a slightly higher temperature, ie 330 ° F instead of 300 ° F. The second stage mixing temperature was 300 ° F, while the third stage mixing temperature was 200 ° F.
It was just F. The fourth stage mixing step was not necessary as the use of the disulfide coupling agent allowed higher first stage mixing temperatures. The elimination of one step in the mixing or compounding operation is a significant advantage.

As is apparent from Table 1, the property of utilizing the solid silica coupling agent composite of the present invention is that carbon black supported carbon black su.
It gave properties very similar to the control using the prepared grade silane coupling agent. Similar properties were achieved utilizing the composites of the present invention, but significant improvements were achieved with respect to the above-mentioned advantages such as a dust-free environment, handling equipment, no appreciable residue left in mixing vessels, etc. Was done.

While in accordance with the patent statutes the best mode and preferred embodiment has been set forth, the scope of the invention is not limited thereto, but rather by the scope of the claims.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 21/00 C08L 21/00 101/00 101/00 F term (reference) 4J002 AA012 AC011 AC021 AC031 AC061 AC081 AE032 AE042 BB002 BB151 BB252 BC001 BC081 BC091 BC131 BF032 DJ016 EF058 EX017 EX027 EX067 EX077 EX087 FD016 FD030 GN01

Claims (10)

[Claims] 1. A tire part comprising at least one rubber composition containing silica and a solid silica coupling agent composite comprising a silica coupling agent and a solid binder. 2. The amount of said silica coupling agent present in the composition is silica 1
The tire component of claim 1, wherein the tire component is about 0.1 to about 20 parts by weight per 00 parts by weight. 3. The solid binder comprises a wax, a thermoplastic polymer, a compatibilizer, a wetting agent, a fatty acid, ethylene vinyl acetate, a stabilizer or combinations thereof, and the amount of the solid binder is The tire part according to claim 1 or 2, which is about 25% by weight to about 90% by weight based on the total weight of the silica coupling agent composite. 4. The silica coupling agent has the formula [Chemical 1]   Where n is an integer from 2 to about 7, k and m are independently 0-3, and R ¹ ~ R⁶Are independently H or alkyl having 1 to 12 carbon atoms, Comprising an organosilane and having an amount of silica of 100 parts by weight of the rubber.
The tire component according to any one of claims 1 to 3, which is about 5 to about 100 parts by weight. 5. The amount of the silica coupling agent is about 1.0 to about 10 parts by weight per 100 parts by weight of the silica, and the silica coupling agent is bis (3-triethoxysilylpropyl) tetrasulfide or bis. (3-triethoxysilylpropyl) disulfide or a combination thereof, wherein the rubber is natural rubber, synthetic polyisoprene, styrene-butadiene rubber, modified styrene-butadiene rubber, butadiene rubber, modified butadiene rubber, or them. The tire component according to claim 4, which is a combination of 6. The tire component of claim 5, wherein the binder is a blend of wax and oxidized polyethylene. 7. The silica is about 5 per 100 parts by weight of the tire component rubber.
7. The tire component of any of claims 1-6 present in an amount of about 100 parts by weight. 8. The silica coupling agent comprises at least one of amino, vinyl, epoxy, mercapto, chloro, bromo, iodo, methacryl, methacryl oil, glycidoxyl, nitroso, imide, octyl, oligomer, ureido or polysulfide. The tire component according to any one of claims 1 to 7, which has one reactive group. 9. The tire component according to claim 1, wherein the silica coupling agent is bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide or a combination thereof. Composition. 10. The tire component according to claim 1, which is a tire tread, a subtread, or a tire carcass.