Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-11-14
2003-05-20
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S318200, C526S113000, C526S123100, C526S160000, C525S372000, C525S386000, C525S363000, C525S268000
Reexamination Certificate
active
06566463
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a multifunctional metallic coagent that improves the properties of a rubber by crosslinking with peroxide and vulcanizing the rubber.
BACKGROUND OF THE INVENTION
As a crosslinker, sulfur and sulfur complex which can be used the rubber curing stocks and the peroxide crosslinker for a long time, but the unsaturated carboxylic acid derivatives and its metallic salts are used the rubber vulcanizing agent in various field recently. Generally, crosslinking with peroxide results in the formation of a covalent bond, so the carbon-carbon bond is rigid and stable, but the cured rubber has the lower tensile and tear strength. And the good heat stability of this covalent bond explains the superior heat aged characteristics of peroxide crosslinking systems. In contrast, crosslinking with the sulfur and its derivatives are thermally weak but are mobile under stress and can slip along the hydrocarbon chain. This mobility explains the superior tensile and tear strength in the sulfur curing systems. Meanwhile, in case of the coagent of unsaturated carboxylic acid, there are so many crosslinkers to cure the rubber, the metallic salt of unsaturated carboxylic acid among them, which is crosslinking with peroxide as an initiator, the crosslink bond results in the formation of an ionic bond. This crosslink bond embodies the best characteristics of both peroxide and sulfur crosslinking systems, that showing a good heat stability and the ability to slip along the hydrocarbon chains giving the superior tensile and tear strength. The di-functional metallic coagent is employed as a metallic coagent of unsaturated carboxylic acid on the market that made from acrylic acid or methacrylic acid reacting with divalent metals such as zinc, calcium and magnesium. This di-functional metallic coagent of unsaturated carboxylic acid is a useful thing to improve the properties and curing the rubber, especially a core of golf ball in a field of elasticity. But, there is a difference between the properties of cured rubber depends on the kind of unsaturated carboxylic acid such as acrylic acid, methacrylic acid even in the metallic coagent of an unsaturated carboxylic acid. For an example, in case of the cured rubber using the metallic salt of acrylic acid that has a good elasticity, but has a defect in the strength of tensile and tear compared the cured rubber using the metallic salt of methacrylic acid. Using two kinds of metallic coagent revealed a good characteristic than using one kind of metallic coagent in some cases.
Moreover, in a shelf-life stability, there is no difference between the properties of metallic coagent of acrylic acid for a period of one year, but the metallic coagent of methacrylic acid should be used within six months for optimum product performance, after a lapse of six months, a falling-off occurred in the product performance. And, there are many difficulties to select a metallic coagent when crosslinking the rubber, because the properties are different depend on the used metal. Generally, there are many multifunctional coagents of unsaturated carboxylic acid in a phase of liquid except a crosslinker in a phase of metallic salt, that is difficult to mix with a rubber and hard to achieve a uniform performance of cured rubber due to a migration of liquid crosslinker in the mixture. In contrast, the metallic salt of unsaturated carboxylic acid in a form of powder, that is easy to get a uniform mixture when blending with a rubber and obtaining a good performance of cured rubber. Thereupon, this inventor made a new multifunctional metallic coagent of unsaturated carboxylic acid for crosslinking a rubber.
DETAILED DESCRIPTION OF THE INVENTION
The metallic coagents according to the present invention have a good characteristic which revealed using two kinds of metallic coagent in cured rubber as mentioned above, and to solve the problems in the mixture of common multifunctional crosslinker in a phase of liquid. The unsaturated carboxylic acids which can be used for a multifunctional metallic salt of unsaturated carboxylic acid in accordance with the present invention are mono-basic acid, such as acrylic acid, methacrylic acid and di-basic acid, such as maleic acid, fumaric acid. As a mono-basic acid, one kind of unsaturated carboxylic acid can be used among acrylic acid and methacrylic acid, or two kinds of unsaturated carboxylic acid can be used among them. And, as a di-basic acid, only one kind of unsaturated carboxylic acid can be used among maleic acid and fumaric acid. Meanwhile, as a metal complex for making a metallic salt of unsaturated carboxylic acid, divalent metal oxide, such as zinc oxide, calcium oxide and magnesium oxide can be used. One kind of metal oxide or two kinds of metal oxide can be used among them. For the reaction of metal oxide and unsaturated carboxylic acid according to the present invention, it must be react in organic solvent, such as toluene, ethanol, methanol and isopropanol that can be used alone or mixed. Basically, this invention is made by reaction from three mols of metal oxide with two mols of mono-basic acid and two mols of di-basic acid, being a multifunctional metallic salt of unsaturated carboxylic acid.
For an example, using two mols of acrylic acid as mono-basic acid, two mols of maleic acid as a di-basic acid and three mols of zinc oxid as a metal oxide, the reactants which eliminated the organic solvent and water due to the reaction that being stable state, trizincdimaleicacrylate is made in a form of white powder. This reaction is represented in the following reaction formula.
The crosslinking of generated trizincdimaleicacrylate with a rubber is as follows. Hereinafter, for the sake of convenience, cis-1,4 polybutadiene is described in the chemical reaction formula of this detail description as a rubber which expresses synthetic rubber, such as polybutadiene rubber, polyisoprene rubber, polystyrenebutadiene rubber, polyethylenebutadiene rubber, silicone rubber and etc. As mentioned above, to crosslink a rubber with organic peroxide as an initiator, reacting and crosslinking by heating in about 150~160° C. in a proper molding machine. This multifunctional metallic salt of unsaturated carboxylic acid crosslinking a rubber with an assistance of peroxide as an initiator in the process of react, generates the crosslink bond in the formation of an ionic bond that giving a good heat stability and the superior tensile and tear strength to the cured rubber. Meanwhile, this trizincdimaleicacrylate is represented in a formula as follows.
The crosslinking reaction of cis-1,4 polybutadiene and this multifunctional metallic coagent is represented in a formula as follows, the cured rubber having ionic bond which giving a superior tensile and tear strength.
The abovementioned multifunctional metallic salt of unsaturated carboxylic acid is obtained from the reactant by using one kind of acrylic acid as a mono-basic acid, one kind of maleic acid as a di-basic acid and one kind of zinc oxide as a metal oxide. Meanwhile, as an other example, a multifunctional metallic salt of unsaturated carboxylic acid from the reactant by using two kinds of mono-basic acid, one kind of di-basic acid and one kind of metal oxide is as follows.
The reactant by using one mol of acrylic acid and one mol of methacrylic acid as a mono-basic acid, two mols of maleic acid as a di-basic acid and three mols of zinc oxide as a metal oxide, that can be generated trizincdimalemethacrylic-acrylate in a white powder. This reaction is represented in a formula as follows.
The crosslinking reaction of cis-1,4 polybutadiene and this multifunctional metallic coagent with an assistance of peroxide at 155~170° C. in a proper molding machine, the cured rubber having strong ionic bond which giving a superior tensile and tear strength in the same way as above. This cured rubber having strong ionic bond is represented in a chemical formula as follows.
The used metal oxide of the abovementioned examples of reaction is only one kind of zinc oxide. But,
Amster Rothstein & Ebenstein
Lim Saeng-Ki
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