Method of preparing low-temperature-cure polymer composition

Details Method of preparing low-temperature-cure polymer composition Method of preparing low-temperature-cure polymer composition

2000-06-30

2002-07-09

Dawson, Robert (Department: 1712)

Coating processes

With post-treatment of coating or coating material

Heating or drying

C428S421000, C428S422000, C428S447000, C524S432000, C524S544000, C524S567000, C524S784000, C524S858000, C526S242000, C528S401000, C528S038000

Reexamination Certificate

active

06416819

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a method of preparing compositions containing a fluorocarbon thermoplastic random copolymer. More particularly, the invention relates to a method of preparing compositions containing a fluorocarbon thermoplastic random copolymer, zinc oxide, an aminosiloxane, and antimony-doped tin oxide particles. Such compositions are capable of being cured at lower temperatures compared with conventional fluorocarbon polymer compositions and are useful as coatings, sheets, or films where high temperature resistance is required.
BACKGROUND OF THE INVENTION
Fluororesins, including both fluorocarbon elastomers and fluorocarbon thermoplastics, are widely used in the form of sheet, film, coatings and laminates in various fields due to their characteristic properties such as good heat resistance, good chemical resistance and good weather resistance. These materials find applications as gaskets and seals in automotive fuel delivery, engine, and powertrain systems, tank and pipe liners, release layers on compression molds, layers on electrophotographic toner fuser rollers or belts, valve stem and rotating shaft sealant coatings, roller and bearing coatings, and sealants for porous materials such as ceramics and fabric, for example. In addition to their characteristic resistance to heat, chemicals, and weather, and depending upon the particular application these fluororesin compositions may also need to provide appropriate frictional characteristics, abrasion and wear resistance, flexibility, processability, and adhesion to a particular substrate.
Polyfluorocarbon elastomers, such as vinylidene fluoride-hexafluoropropylene copolymers, are tough, wear resistant and flexible elastomers that have excellent high temperature resistance, but relatively high surface A energies, which compromise applications where release properties are critical, for example as release layers on compression molds or outer layers on electrophotographic toner fuser members.
Fluorocarbon resins like polytetrafluoroethylene (PTFE) or fluorinated ethylenepropylene (FEP) are fluorocarbon thermoplastics which have excellent release characteristics due to very low surface energy. Fluorocarbon thermoplastic resins are, however, less flexible and elastic than fluorocarbon elastomers and often require high temperature curing for long time periods to sinter the polymer into a continuous and useful layer or sheet.
Both fluorocarbon elastomers and fluorocarbon thermplastics have been used to prepare high temperature resistant surfaces. For example, U.S. Pat. No. 4,999,221 describes a process for powder coating a substrate with a fluoroplastic material to provide a heat resistant surface layer. U.S. Pat. Nos. 5,919,886 and 6,020,450 describe a room temperature curable fluoropolymer composition containing an organosilicon compound and a condensation accelerator having improved heat resistance and weatherability.
U.S. Pat. Nos. 5,948,479 and 6,068,931 describe composite materials for self-lubricating slide bearings containing a fluorothermoplastic composite overlayer on a porous metal bearing.
Fluororesin-containing compositions have also been successfully employed in various electrostatographic applications. For example, U.S. Pat. Nos. 4,568,275 and 5,599,631 disclose a fuser roll having a layer of fluorocarbon elastomer and a fluorinated resin powder. However, the fluorocarbon resin tends to phase separate from the fluorocarbon elastomer thereby diminishing performance.
U.S. Pat. No. 4,853,737 discloses a fuser roll having an outer layer comprising cured fluorocarbon elastomers containing pendant amine functional polydimethylsiloxane that are covalently bonded to the backbone of the fluorocarbon elastomer. However, the amine functional polydimethylsiloxane tends to phase separate from the fluorocarbon elastomer.
U.S. Pat. No. 5,582,917 discloses a fuser roll having a surface layer comprising a fluorocarbon-silicone polymeric composition obtained by heating a fluorocarbon elastomer with a fluorocarbon elastomer curing agent in the presence of a curable polyfunctional poly(C1-6 alkyl) siloxane polymer. However, the resulting interpentrating network (IPN) has relatively high coefficient of friction and relatively low mechanical strength. After a period of use, the release property of the roller degrades and paper jams begin to occur.
U.S. Pat. No. 5,547,759 discloses a fuser roll having a release coating layer comprising an outermost layer of fluorocarbon resin uniquely bonded to a fluoroelastomer layer by means of a fluoropolymer containing a polyamide-imide primer layer. Although the release coating layer has relatively low surface energy and good mechanical strength, the release coating layer lacks flexibility and elastic properties and can not produce high quality of images. In addition, sintering the fluorocarbon resin layer is usually accomplished by heating the coated fuser member to temperatures of approximately 350° C. to 400° C. Such high temperatures can have a detrimental effect on the substrate to which the fluorocarbon resin has been applied, especially, for example, if the substrate is a polymeric material. It would be desirable to provide a fluorocarbon composition that can be formed and/or cured without damaging the substrate to which it has been applied.
U.S. Pat. No. 5,595,823 discloses toner fusing members which have a substrate coated with a fluorocarbon random copolymer containing aluminum oxide. Although these toner fusing members have proved effective and have desirable thermal conductivity, they have a problem in that there can be toner contamination. The advantage of using the cured fluorocarbon thermoplastic random copolymer compositions is that they are effective for use with toner release agents which typically include silicone.
U.S. Pat. No. 6,035,780 describes a process to prepare a compatibilized blend of a fluoroelastomer and a polysiloxane useful for electrostatographic and liquid ink printing machine applications. The compatible blend is reportedly useful as a component of long-life fuser rolls, backing rolls, transfer and transfuse belts and rolls and bias charging and biastransfer rolls.
U.S. Pat. No. 5,464,698 discloses toner fusing members which have a substrate coated with a fluorocarbon random copolymer containing tin oxide. Although these toner fusing members have proved effective and have desirable thermal conductivity, they have a problem in that there can be toner contamination.
Commonly-assigned U.S. Pat. No. 6,041,210 describes a toner fusing member having an overcoat layer including electrically conductive fine powders having a weight percent between about 30 to 80 weight percent. Although these toner fusing members have proved effective in suppressing electrostatic charge build up, they have a problem in that there can be toner contamination.
As evidenced by the above description, fluororesin compositions have been widely utilized in a variety of critical applications requiring resistance to severe or aggressive environments, abrasion and wear resistance, surface lubricity, and release properties. However, it has been extremely difficult to provide a fluororesin composition which simultaneously provides most or all of these characteristics and can be cured at temperatures as low as room temperature. It is toward a solution to this problem that the present invention is directed.
SUMMARY OF THE INVENTION
The present invention provides a method of preparing a composition containing a fluorocarbon thermoplastic random copolymer that is easily processed into a coating or sheet having improved release properties, surface lubricity, mechanical strength, and low curing temperatures. The method comprises the steps of:
(A) providing a mixture having:
(i) a fluorocarbon thermoplastic random copolymer having subunits of:
—(CH
2
CF
2
)x—, —(CF
2
CF(CF
3
)y—, and —(CF
2
CF
2
)z—,
 wherein
x is from 1 to 50 or 60 to 80 mole percent,
y is from 10 to 90 mole percent,
z is from 10 to 90 mole percent,
x+y+z equals 100 mole percent;
(ii) a filler co

Affiliated with

Also associated with

Rating

Method of preparing low-temperature-cure polymer composition does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method of preparing low-temperature-cure polymer composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of preparing low-temperature-cure polymer composition will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2846959