Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1991-10-15
2002-04-23
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S757000, C524S761000, C524S762000, C568S580000, C264S213000
Reexamination Certificate
active
06376588
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to mandrel release agents. More particularly the invention relates to three component compositions which function as mandrel release agents for processing rubber based elastomers. These compositions combine the more desirable properties traditionally found in liquid lubricants and polyethylene glycol lubricants. They have optimum viscosity at application temperatures and result in immobile films which are smooth without brittleness at ambient temperatures.
In addition, these release agents are stable at rubber curing temperatures, compatible with most natural and synthetic rubber parts, do not cause swelling or shrinkage of parts and provide a lubricating function during demolding. The release agent compositions can be adapted to cover a wide range of viscosities, lubricities and melting points to fit different types of rubber parts and molding equipment.
BACKGROUND OF THE INVENTION
In many areas of plastics and rubber processing release agents are important aids. These release agents are found in the market under different names such as mandrel release agents, mold release agents, antiadhesion promoters, demolding agents, antiadhesives and separating agents. There are fields of applications in which the use of release agents is critical to manufacture certain products and other applications where the agents modify the surface or merely facilitate the work. More detail on the role of such agents is discussed in the Journal Article titled “STATE OF DEVELOPMENT OF RELEASE AGENTS USED IN PLASTICS PROCESSING,” Rathje, G., Kunststuffe;
German Plastics
, Vol. 75, No. 2, February 1985, pp. 12-13. Details are given on conventional release agents, separation systems and coating techniques.
An article in a Hungarian journal describes some adhesion preventing agents in the manufacture of rubber products. Due to heat introduced and/or released during molding and vulcanization of rubber products, it is frequent that the molded products adhere to the molds and do some damage to the product at the time of demolding. Different so-called mold lubricants are used to prevent this adhesion and ease the product release. (See Muanyag Es Gumiv Vol. 21, No. 9, September 1984, pp. 271-273).
Another journal article discusses the fast growing market for lubricants in the plastics industry. The variety of the chemical compositions of the plastics to which they are added and the processes that are used in conversion of them coincides with a wide range of effects. See Chemische Industrie International (English Translation), No. 3, 1987, pp. 13, 16-19.
A product bulletin,
The Polyglycol Handbook
, published by Dow Chemical Co. , 1988, pp. 22-23, discusses the use of polyethylene glycols in the role of mold release agents and lubricants in the rubber industry.
The Dow bulletin indicates polyethylene glycols can be used in mold release agents for latex foams. A lower molecular weight liquid polyethylene glycol can be used as a mold release agent in the production of articles prepared from latex rubber. In addition, water-soluble liquid polyglycols are used alone, or in combination with higher molecular weight polyglycols as mold and mandrel lubricants in the production of fire hose, rubber hose and shoe heels.
According to
JEFFOX® Polyethylene Glycols
, published by Texaco Chemical Company, 1983, at pages 12-13, several polyethylene glycols in the JEFFOX® product line are useful as mold release agents.
A bulletin titled
Newpol LB Series
50
HB Series
75
H Series
(Bulletin No. D105-201-1), published by Sanyo Chemical Industries, October 1976, contains a discussion of that company's product line of polyalkyleneamines and their use as mold release agents.
Japanese Patent J58132090-A discloses compositions for releasing rubber hose from mandrel which are prepared by addition, polymerizing NH
3
or amine (e. g. mono-, di- or triethanol amine) with an alkylene oxide such as ethylene oxide and/or propylene oxide.
Conventional releasing agents include polypropylene glycol, polyoxypropylene glycerol ether, polyoxyethylene/polyoxypropylene block copolymer, polyoxypropylene/polyoxyethylene glycerol ether, polyethylene glycol, silicone oil, animal or vegetable oil or mineral oil, Ibid.
In a paper delivered at the Society of the Plastics Industry, Reinforced Plastics/Composite Institute, Annual Conference-Proceedings 43rd, published by SPI, Washington, D.C., USA, 1988, pp. 12A.1-12A.6, James Werner reviewed the benefits of using perfluorinated polyethers as mold release agents in rotational molding of polyethylene and polycarbonate, molding of epoxy resins and graphite fibers, molding of solid propellant rocket fuels and molding of intricate ceramic parts.
A Romanian patent, RO-82386, discloses a mixture which contains by weight 5-60% polyether polymer and/or copolymer of the formula:
X—(OCHYCH
2
)
n
—(OCH
2
CHY)
m
—OH
where X is H, Me, Et, C
3
H
7
or C
4
H
9
, Y is H or Me, n and m are integers of from 1-50 and 0.1-5% ionic or nonionic surfactants, such as an alkylaryl sulphonate and sulphated or ethoxylated fatty alcohols, 1-6000 ppm w.r.t. total mixture, corrosion inhibiter specific to the contacting metal and the balance deionized water. The composition can be used as antiadhesive in the production of rubber articles, plastic materials, synthetic resins and in casting concrete.
In U.S. Pat. No. 4,217,394 there are disclosed mold-release compositions suitable for lubricating metal molds such as the type used in molding natural and synthetic rubber and other polymers. The mold release agents are oxidation stable homopolymers and copolymers, i.e. block or heteric polyoxyalkylene lubricant compounds. The lubricants can be used alone or in mixtures with polyoxyalkylene lubricant compounds known in the art. Where polyalkylene glycols are used in the art as mandrel or mold release agents the applications for each are usually limited-because of the narrow range of viscosity, lubricity and melting points which are suitable for each type of polyethylene glycol.
In the art relating to release agents, traditionally liquid lubricants and polyethylene glycol lubricants have been useful, although some undesirable properties are characteristic of each.
Liquid lubricants are usually diluted and the amount of dilution controls the viscosity of the film in the mold. Generally, the viscosities of the films tend to be higher, but they are still in a liquid state.
Alternatively, polyethylene glycols can be used as mold release agents. These compounds are used in solid form. They are applied in molten form and are often of a thin viscosity at application temperatures. As these agents cool on the molded parts they leave a solid film that is brittle. With articles such as rubber hoses, elastomeric parts or flexible parts a solid film exhibiting brittleness will flake off.
There is a need in the art for a release agent which represents a combination of the more desirable properties of both liquid lubricants and polyethylene glycol lubricants. It would represent a distinct advance in the art if a release agent were formulated which had the most desirable viscosity at application temperatures and resulted in a solid film which was smooth but exhibited no brittleness or cracking.
A release agent composition which could be adjusted to cover a wide range of viscosities, lubricities and melting points and was adaptable to fit a number of different types of molding equipment would resolve many of the problems commonly associated with work in the field of molding rubber and plastic.
It would be especially valuable in the art to define a release agent composition possessing these desirable characteristics wherein the melting point of the formula could be precisely controlled by one of the components in the composition.
SUMMARY OF THE INVENTION
In accordance with the foregoing, the instant invention is directed to a three-component water soluble mold release composition for processing rubber based elastomers comprising one or more water soluble copolymers of ethylene oxide and propylene oxide,
Cain Edward J.
Huntsman Petrochemical Corporation
O'Keefe Egan & Peterman, LLP
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