KR20070017387A - Abrasion resistant fluoropolymer compositions containing micropulp - Google Patents

Abstract

The present invention provides a wear resistant composition comprising an fluoropolymer and an effective amount of micropulp, wherein the wear resistance of an article, such as a film formed from the composition, is increased by at least 25% relative to a film formed from the fluoropolymer alone. In a particularly preferred embodiment, the composition further contains an effective amount of pigment to further increase the wear resistance of the film formed from the composition as compared to the film formed from the fluoropolymer alone. The present invention is particularly useful for films formed on fixing rolls.

Abrasion Resistant, Fluoropolymer Composition, Fine Pulp

Description

Wear-resistant fluoropolymer composition containing fine pulp {ABRASION RESISTANT FLUOROPOLYMER COMPOSITIONS CONTAINING MICROPULP}

The present invention relates to fluoropolymer compositions containing adjuvants that increase the wear resistance of articles formed from the compositions.

Fluoropolymer resins have excellent stability to light, heat, solvents, chemical attack and electrical stress and thus provide desirable properties for articles made from such polymers or substrates coated with polymer films. Such resins, in particular perfluoropolymer resins, are known for their low surface energy and peel / non-stick characteristics. Incorporation of adjuvants into such resins can extend their service life by improving mechanical properties, such as wear resistance, but this addition reduces the peeling properties of the polymer.

One important application of fluoropolymers is electrostatographic reproduction in which an electrostatically charged toner is anchored in a receiver (eg paper or film) that visualizes an electrostatic latent image. The use of a fluoropolymer resin film coating on a heated metal fuser roll prevents the toner from sticking to the fusing roll and release surfaces that allow more toner to be fixed to the receiver for the production of high quality printed images. It provides a heat resistant polymer film having a. The heated fixing rolls are usually heated to a high temperature of about 200 ° C. to melt the toner particles electrostatically deposited on the receiver, and then peel off the resulting molten phase while adhering to the receiver. The molten toner particles, if adhered to the fixing roll, may later be deposited on the supplied receiver to provide an unwanted phase. Accordingly, fixing roll coating applications of fluoropolymer resins require critical requirements for firmly peeling the molten toner that becomes a tacky material due to its melt properties and the need for adhesion to the receiver. Fluoropolymer resin coatings have been used successfully in this application, but picker fingers are removed by the receiver in sequential contact with the fixing roll, and even more severely, to remove the receiver from the fixing roll by friction with the fixing roll surface. Has the drawback to be worn by The problem is how to increase the wear resistance of the coating without adversely affecting the peeling properties of the coating.

Summary of the Invention

The present invention solves this problem by providing a composition comprising a fluoropolymer and an effective amount of micropulp, wherein the wear resistance of the surface of the article formed from the composition is increased by at least 25% relative to the surface of the article formed from the fluoropolymer alone. do. Preferred forms of the article are, for example, unsupported or support films such as coatings on substrates, for example fixing rolls. While the description of the present invention will be based on the preferred film morphology, this description is generally applicable to articles such as blocks, panels, sheets and other shaped forms in order to implement the same improvements as have been obtained for films. In general, the compositions of the present invention can be applied to improve their peeling properties as well as the wear resistance of fluoropolymer resin coatings, in particular without adversely affecting the peeling coating on the fixing roll during electrostatic regeneration. Micropulp is an organic fiber material comprising fibrils having a cross section having a width dimension of less than 10 nanometers. When such sufficient fibrils are formed into a coating on a substrate, for example a fixing roll core, they are present on the surface of the coating to provide improved wear resistance. Despite the fibril properties of the micropulp, the coating wears even with repeated use so that the surface of the coating possesses suitable peeling properties. Fresh fibrils entering the wear surface of the coating from the fine pulp prevent the molten toner particles from adhering to the fixing roll coating instead of the receiver.

In a preferred embodiment, the composition further contains an effective amount of pigment to further increase the wear resistance of the film formed from the composition as compared to the film formed from the fluoropolymer alone.

In fix roll coating applications, the composition is usually used in small amounts of electroconductive particulate material in an amount effective to prevent accumulation of electrical charge on the fix roll, which can attract toner particles from the contact with the fix roll and thereby from the receiver prior to fixation. It contains. Since this adjuvant has a negligible effect on the abrasion resistance of the fluoropolymer resin coating, it can be included in the fluoropolymer in abrasion tests that determine the abrasion resistance of the fluoropolymer itself.

The micropulp has a preferred volume average length in the range of 0.01 to 125 μm. Preferably, the micropulp is a synthetic organic polymer, most preferably aromatic polyamides commonly known as aramids.

The invention also relates to a film formed from the composition, in particular a film formed on a fixing roll.

Detailed description of the invention

The improved methods and compositions of the present invention that provide both good wear resistance and good peeling are best illustrated by using this composition as a film coating for a fixing roll in copiers and laser printers. For example, during electrostatic regeneration in a copier, a uniformly charged image roll is exposed to a laser to produce a series of electrostatic images. Toner is then applied to each phase on the image roll to produce a series of toner images corresponding to the electrostatic image. The toner image is transferred to a receiver, for example paper or film. The receiver having the toner image is separated from the image roll and supplied to the fixing apparatus. Usually, the fixing device is composed of two rolls which form a nip while the receiver passes through. The top roll is generally a fluoropolymer coated metal roll, referred to below as "fixing roll". The second roll, hereinafter referred to as the "support roll", cooperates with the fixing roll to form a nip and is usually composed of a flexible elastomeric material, for example silicone rubber. The fixing roll is often heated by an internal heat source disposed in the core of the fixing roll.

The use of a fluoropolymer resin film coating on a heated metal fixing roll prevents the toner from sticking to the fixing roll and creates a heat resistant polymer film having a peeling surface that allows more toner to be fixed to the receiver for production of a high quality printed image. to provide. However, a large volume of paper and picker finger pressure on the fixing roll surface passing through the copier will cause abrasion effects that cause the coating to wear to the prior art fluoropolymer coating, thus losing its effectiveness as a peeling surface. As shown in the examples below, the fluoropolymer resin compositions of the present invention containing an effective amount of micropulp have at least 25%, preferably 50%, abrasion resistance of films formed from the compositions compared to films formed from fluoropolymers alone. Improve over.

The micropulp adjuvant used in the present invention is disclosed in US Pat. It has a volume average fiber length of less than one tenth the size of conventional short aramid fibers used in matrix resin reinforcement. The present invention achieves improved abrasion resistance using micropulp in the absence of fibril-free aramid microparticles that are fully fibrils, ie, achieve this improvement without reducing peeling. In addition, unexpectedly, when certain pigments, such as zeolites, are added to the fluoropolymer composition containing the micropulp, the wear resistance of the film formed from the composition far exceeds 100% of the film formed from the fluoropolymer alone, even There is a synergistic effect that results in improvement over 200%.

Fluoropolymer

The fluoropolymers in the composition of the film of the present invention are trifluoroethylene, hexafluoropropylene, monochlorotrifluoroethylene, dichlorodifluoroethylene, tetrafluoroethylene, perfluorobutyl ethylene, perfluoro ( Alkyl vinyl ethers), vinylidene fluoride and vinyl fluoride and their blends and polymers and copolymers, and blends of said polymers with nonfluoropolymers.

The fluoropolymer used in the present invention is preferably melt processable. Melt processability means that the polymer can be processed in the molten state (ie, from shaped to molded articles exhibiting sufficient strength and toughness useful for their intended purpose, such as films, fibers, tubes, and the like). Examples of such melt processable fluoropolymers include copolymers of tetrafluoroethylene (TFE) and one or more fluorinated copolymerizable monomers (comonomers) present in the polymer, substantially reducing the melting point of the copolymer, the TFE homopolymer, polytetra And in an amount sufficient to reduce the melting point of fluoroethylene (PTFE) to a melting point of, for example, 315 ° C. or less. Such fluoropolymers include copolymers of tetrafluoroethylene (TFE) or chlorotrifluoroethylene (CTFE) which are polychlorotrifluoroethylene. Preferred comonomers having TFE include perfluoroolefins having 3 to 8 carbon atoms, such as hexafluoropropylene (HFP), and / or linear or branched alkyl groups containing 1 to 5 carbon atoms. Perfluoro (alkyl vinyl ether) (PAVE). Preferred PAVE monomers are those in which the alkyl group contains 1, 2, 3 or 4 carbon atoms, and the copolymer can be formed using several PAVE monomers. Preferred TFE copolymers include FEP (TFE / HFP copolymer), PFA (TFE / PAVE copolymer), PFE is PEVE and / or PPVE and MFA, and TFE / HFP / PAVE (the alkyl group of PAVE has two or more carbon atoms TFE / PMVE / PAVE). Melt processable copolymers typically have a predetermined amount of comonomer to provide a copolymer having a melt flow rate of about 1-100 g / 10 min as measured according to ASTM D-1238 at temperatures standard for the particular copolymer. It is prepared by incorporating in a copolymer. Typically, melt viscosity is 10 ² Pa.s to about 10 ⁶ Pa.s, preferably 10 ³ to about 10 ⁵ Pa, measured at 372 ° C. by a modified ASTM D-1238 method as described in US Pat. No. 4,380,618. S range. Further melt processable fluoropolymers are copolymers of ethylene or propylene with TFE or CTFE, in particular ETFE, ECTFE and PCTFE. Further useful polymers include film forming polymers of polyvinylidene fluoride (PVDF) and vinylidene fluoride, as well as copolymers of polyvinyl fluoride (PVF) and copolymers of vinyl fluoride.

Although the fluoropolymer component is preferably melt processable, polytetrafluoroethylene (PTFE), including modified PTFE, which is not melt processable, can be used with or in place of the melt processable fluoropolymer. Modified PTFE is PTFE containing small amounts of comonomer modifiers that improve film forming ability during baking (settlement), for example perfluoroolefins, in particular hexafluoropropylene (HFP) or perfluoro (alkyl vinyl) Ether (PAVE), wherein the alkyl group contains 1 to 5 carbon atoms, with perfluoro (ethyl vinyl) ether (PEVE) and perfluoro (propyl vinyl) ether (PPVE) being preferred. The amount of such modifiers, generally less than 0.5 mole%, is insufficient to provide melt fabricability to PTFE. In addition, PTFE may simply have a single melt viscosity, usually at least 1 × 10 ⁹ Pa · s, but a mixture of PTFE with different melt viscosity may be used to form the fluoropolymer component. This high melt viscosity suggests no melt processability as PTFE does not flow in the molten state.

As will be appreciated by those skilled in the art, mixtures of different types of fluoropolymers can be used to practice the present invention.

The composition of the present invention includes a composition and a cover applied to a fixing roll to form a cover thereon, or, more generally, a composition of a film such as formed on the surface of the fixing roll. In the case of the composition used to form the cover, such fluoropolymers used in the present invention are in the form of particles having an average particle size of less than 1 μm and up to about 100 μm. Many fluoropolymers are prepared by aqueous dispersion polymerization, wherein the polymerized fluoropolymer particles typically range from 0.01 to 0.3 μm in diameter. Particle sizes disclosed herein are average particle sizes. In addition, the fluoropolymer component may be present in a large particle diameter, for example 5 to 100 μm, preferably 10 to 20 μm. Such large particle sizes can be made by flocculation or spray drying from dispersions as described in US Pat. No. 6,518,349 B1 (Felix et al.) Using an optional milling step to achieve the desired particle size. In one preferred embodiment, both submicron particles (dispersion particles) and large particles (powder particles) are present.

Although the fluoropolymers used in the present invention are melt processable, films of compositions containing fluoropolymers generally generally provide the composition as a liquid medium in which the fluoropolymer particles are dispersed in an organic solvent or water or a mixture thereof. It is formed by applying this liquid composition to a substrate to be coated, followed by drying and baking the coating to form a release coating on the substrate. Preferably, this dispersion is from both of the aforementioned particle size groups, for example from about 15% to about 30% by weight micron size particles and from about 10% to about 20% by weight large size particles. Fluoropolymer particles.

Examples of organic solvents include N-methylpyrrolidone, butyrolactone, and high boiling aromatic solvents include alcohols such as methanol, ethanol, isopropanol and t-butanol, ketones such as acetone and methyl ethyl ketone ( MEK) and mixtures thereof.

In another embodiment, the compositions of the present invention may be in the form of a powder that powder-coated a surface, such as a surface of a fixing roll, to form a film. In both embodiments, the powder coating and the coating from the liquid medium, the melt processability of the fluoropolymer enables the fluoropolymer particles to settle together during baking to form a continuous film (coating).

Fine pulp

The composition of the present invention comprises an effective amount of micropulp and fluoropolymer of fibrous organic material that increases the wear resistance of a film formed from the composition to at least 25%, preferably at least 50%, relative to a film formed from fluoropolymers alone. . In the case of baked compositions, ie films, the micropulp comprises from 0.1% to 4% by weight, preferably from about 0.25% to 3% by weight, based on the total weight of the dry components, including the fluoropolymer.

Micropulp and its preparation are both described in detail in US patent applications US 2003/0114641 A1 and 2004/0119948 by Kelly et al. In general, the micropulp used in the present invention is a fibrous material comprising a combination of two or more interlocking combinations of web, dendritic, branched, mushroom or fibrillated structures. Generally, the shape of the particles forming the micropulp is a bundle of fibers of fine fibrils, as shown in FIG. 4 of US 2003/0114641 A1. Organic fibers suitable for use in the present invention are organic synthetic polymers such as aliphatic polyamides, polyesters, polyacrylonitriles, polyvinyl alcohols, polyolefins, polyvinyl chlorides, polyvinylidene chlorides, polyurethanes, polyfluorides. Carboxylic, phenolic, polybenzimidazole, polyphenylenetriazole, polyphenylene sulfide, polyoxadiazole, polyimide, aromatic polyamide, or mixtures thereof. More preferred polymers are prepared from aromatic polyamides, polybenzoxadiazoles, polybenzimidazoles or mixtures thereof. Even more preferred organic fibers are aromatic polyamides ((p-phenylene terephthalamide), poly (m-phenylene isophthalamide) or mixtures thereof).

More particularly, aromatic polyamide organic fibers disclosed in US Pat. Nos. 5,811,042, 3,869,430, 3,869,429, 3,767,756, and 2,999,788, all of which are incorporated herein by reference, are preferred as starting materials in the production of micropulp. As described in detail in US 2003/0114641 A1, fine pulp in which the organic fibers are contacted with a medium containing liquid and solid components and stirred, for example, by rolling the medium and the organic fiber to disperse the organic fibers in the medium. To produce a fine pulp. Micropulp can be used as a slurry or separated from the medium. Some commercially available organic fibers useful as starting materials in making micropulps are available as fibers from DuPont Company, Wilmington, Delaware. Such fibers may be present in the form of continuous filaments, short fibers, pulp or fibrids made directly or cut from the continuous filaments. Typically, the length of such short fibers varies from about 1 mm to 12 mm. Such aramid fibers are available as Kevlar® Aramid Pulp, 1 F543, 1.5 mm Kevlar® Aramid Floc 6F561, DuPont Nomex® Aramid Fibrid F25W. The rolling treatment reduces the length of the starting fiber by at least 10 times while fibrillating the fiber.

Other suitable commercial organic synthetic polymer fibers are all Xylon® PBO-AS (poly (p-phenylene-2,6-benzobisoxazole) fibers, xyl, supplied by Toyobo, Japan Ron® PBO-HM (Poly (p-phenylene-2,6-benzobisoxazole)) Fiber, Dyneema® SK60 and SK71 Ultra High Strength Polyethylene Fiber, Engineering Fiber Technologies, Shelton, Connecticut Celanese Vectran HS pulp supplied by Engineering Fibers Technology, EFT 1063-178, CFF fibrillated acrylic supplied by Sterling Fibers Inc., Face, FL. Fiber, Tiara Aramid KY-400S pulp supplied by Daiko Chemical Industries, Ltd., Sakai City 1 Tepo-Jo Daicel Chemical Industries, Japan.

Preferably, the fine pulp included in the fluoropolymer composition of the present invention has a volume average length in the range of 0.01 μm to 125 μm, preferably 1 μm to 50 μm, more preferably 5 μm to 30 μm. The shorter the volume average fibril length of the micropulp, the smoother the surface of the film formed from the composition. As the volume average length increases, the surface hardness of the resulting film also increases, which impairs the peeling properties of the film. We performed an additional step of honing the surface of the film formed from the composition using fine grit, for example 600 grit, so that even longer volume average fibril lengths of up to 125 μm provide improved wear resistance. It has been found that it can still provide good peeling properties. If the film forms the surface of a roll, for example a fixing roll, the roll rotates and the horn can pass along its surface during this rotation to provide the desired smoothness. This honing removes the “peaks” of the micropulp and the placed fluoropolymer, but the resulting honed film nevertheless has improved wear resistance and good peeling while retaining the fluoropolymer on the surface with the aid of the fibrillable micropulp Provide both properties. The smoothness of the desired film surface is generally determined visually, ie the surface of the film should generally have a smooth surface with no topography. The inventors have unexpectedly found that when the micropulp has a volume average length of 5 to 30 μm, in particular, optimum wear resistance can be obtained with good peelability in the fixing roll coating. Films from the compositions of the present invention containing such small volume average lengths form smooth film surfaces without the need for honing to achieve surface smoothness.

The volume average length as used herein as determined by laser diffraction and described in Example 13 of US 2003/0114641 A1 means the following.

In general, the micropulp comprising fibrous organic material has an average surface area in the range of 25 to 500 m 2 / g, preferably 25 to 200 m 2 / g, more preferably 30 to 80 m 2 / g. Fibrils of fine pulp generally have an aspect ratio (length to diameter) of at least 10: 1. In addition, the inventors have unexpectedly found that incorporating micropulp into the coating composition provides a coating with improved wear resistance and good peelability and can be applied to a substrate, for example a fixing roll. The particles of the micropulp and fluoropolymer can be mixed with each other, but as described below, they do not interact with each other even under baking conditions forming a film from the composition. Fluoropolymers are known to be nonpolar and chemically non-reactive, so no detectable reaction occurs between the fluoropolymer and the micropulp in films formed from the compositions.

Other supplements

The composition may contain other auxiliaries such as pigments and electroconductive particulate materials in addition to the fluoropolymer and the micropulp. In addition, when forming films using the present compositions, these auxiliaries are also non-reactive to fluoropolymers and micropulps.

In general, it is preferred that the coating composition used on the fixing roll contains an effective amount of electroconductive particulate material to assist in the dissipation of static accumulation. In a preferred embodiment of the present invention, electroconductive particulate material such as mica is included in the composition of the present invention. Mica becomes conductive due to coating on mica flakes, for example antimony or tin oxide. Alternatively, the composition may contain graphite or Ketjen Black as the electroconductive aid. Electrical conductivity means that the surface resistance of the particulate matter measured by a pinion meter is less than 10 ⁸ ohms / square. The amount of electroconductive particulate material effective to prevent static accumulation depends on the specific material used. For example, when the particulate material is conductive carbon, only about 1 to 2 weight percent is needed. If the material is an electroconductive mica (mica coated with an electroconductive material), generally about 3 to 8% by weight is required. This weight is based on the total dry weight of the composition, which is equal to the baked weight. Both electroconductive carbon and electroconductive mica can be used in the same composition to reduce the amount of electroconductive carbon and reduce the effect on the color of the composition.

Mica exists in the form of plate-shaped particles. Preferred mica platelets have an average particle size of about 10 to 200 microns, preferably 20-100 microns, and up to 50% of the particle pieces have an average particle size of greater than about 300 microns. Mica particles coated with an oxide layer are described in US Pat. Nos. 3,087,827 (Klenke and Stratones), 3,087,828 (Linton) and 3,087,829 (Linton).

We have found that combining certain pigments and micropulps in compositions containing fluoropolymers exhibits an unexpected increase in wear resistance. In particular, the pigment of the zeolite which is further described below is especially preferable. In addition, preferred compositions of the present invention comprising fluoropolymers and micropulps contain an amount of pigment that is effective to further increase the wear resistance of films formed from the compositions as compared to films formed from fluoropolymers alone. The abrasion resistance of films from compositions comprising fluoropolymers, micropulps and pigments is increased by at least 50%, preferably at least 100%, more preferably at least 200% and most preferably at least 300%.

In a particularly preferred embodiment, the compositions of the invention are liquid dispersions of fluoropolymers, micropulps and pigments, wherein said pigments generally comprise from about 1 to about 12% by weight, based on the total weight of the dry film. . When the composition is formed into a film, the total amount of micropulp, electroconductive particulate material and pigments ranges from at least about 4% by weight, preferably from about 4% to about 14% by weight, based on the total weight of these components and the fluoropolymer. Exists as. The composition may contain such large amounts of pigments and electroconductive materials, and because these aids are less dense than fluoropolymers, they contain these aids in much less volume percent. Thus, the composition of the present invention contains about 86 to 96% by weight of the fluoropolymer, the volume percentage of this component is much higher.

As preferred pigments, zeolites are reversibly hydrated aluminum silicates which generally contain alkali or alkaline earth metal oxides which can sometimes be ion exchanged with other metals or hydrogen. The general structure definition is as follows:

M _{x / n} [(AlO ₂ ) _x (SiO ₂ ) _y ] mH ₂ O

In the above formula, M is a cation of valence n, and n is 1 or 2. The ratio of x to y can vary from one to a large number as is known in the art. Zeolites include many naturally occurring minerals and synthetic materials. A class of minerals known as quasi-feldspar are closely related to zeolites and are included in the meaning of the term zeolite herein. Quasi-feldspars, including open-walled and large cavities, are known to be closely related to zeolites. Preferred zeolites are ultramarine blue (UMB), which is an alkali metal aluminum silicate. In general, the particle size of the zeolites used in the present invention is generally less than 5 μm, typically in the range of 0.5 to 3 μm.

The addition of ultramarine blue to the composition provides a smooth coating and a visible and easily identifiable blue film coating.

Unexpectedly, when zeolites and micropulps are present in the same fluoropolymer composition, both contribute to the abrasion resistance of the film surface formed from the present composition, resulting in higher wear resistance when both auxiliaries are used and desired peeling of the film surface. It can hold properties.

Film formation

In one embodiment, the film of the composition of the invention is applied directly to the substrate as a liquid dispersion by conventional means, such as spray coating, dipping, roller coating or curtain-coating, followed by 310 to 430 It is formed by heating and settling at a temperature of < RTI ID = 0.0 > C < / RTI >

In a preferred embodiment, the substrate is first primed using a primer composition containing a heat resistant polymer binder that allows the primer layer to adhere to the substrate, and then the dispersion of the invention is applied. Optionally, such binder composition may contain a fluoropolymer. The binder component consists of a polymer that forms a film upon heating for fixation and is also thermally stable. This component is known in primer applications for non-tacky finish, fluoropolymer containing primer layer adhesion to a substrate and film formation in and as part of the primer layer. In general, the binder does not contain fluorine but adheres to the fluoropolymer.

Examples of non-fluorinated heat stabilized polymers include polyamideimide (PAI), polyimide (PI), polyphenylene sulfide (PPS), polyether sulfone (PES), polyarylene-etherketone, and usually polyphenylene Poly (1,4 (2,6-dimethylphenyl) oxide) known as oxide (PPO). In addition, these polymers do not contain fluorine and are thermoplastic. All of these resins are thermally stable at temperatures above 140 ° C.

In an alternative embodiment, the film is obtained by electrostatically applying the powder composition of the invention directly to a substrate, preferably a fixing roll or a primed substrate, followed by heating and fixing at a temperature in the range from 310 ° C to 430 ° C.

When the composition of the present invention is applied to the primer as an overcoat, the primer layer generally has a thickness of about 4 μm to about 15 μm and the overcoat generally has a thickness of about 12 μm to about 50 μm. Multiple overcoats may be applied.

The composition of the film of the present invention may be formed on any substrate material, metal (eg, in the case of fixing rolls and ceramics), which may be resistant to baking temperature, examples of which are aluminum, anodized aluminum, cold rolled steel. Steel, stainless steel, enamel, glass and pyroserum. The substrate may be smooth, etched or grit blasted.

Preferred products having a surface film formed using the compositions of the present invention include fixing rolls and belts, pipes, conveyors, including tanks, chutes, roll surfaces, cutting blades, iron sole plates, cookware, roasting, and the like. And chemical processing equipment. Other applications include anti-graffit covers for films, flexible fabrics, and interior or exterior building panels used inside aircraft, and protective covers for many thermoplastic and thermoset surfaces and components.

Test Methods

Abrasion Test-Trust Method

The wear index of the coating was determined using a Palex friction and wear tester, available from Falex coperation, Sugar Grove, Ill., Designated ASTM D3072. The stationary aluminum washer specimen is placed in the lower specimen holder. Washer structure is specified in ASTM D3072. The coated rotating wafer specimen is mounted to a rotating spindle in contact with the lower stationary aluminum washer specimen. Then a load of 21.8 kilograms is applied. Set the sample rotation speed to 500 rpm. After every 000 cycles, the test is stopped and the weight loss recorded. The test is continued until 30,000 cycles or until the substrate begins to appear (the substrate is visible). The wear index is determined in terms of the total cycles of wear (cycles / milligrams of wear) per total weight loss in milligrams.

Abrasion Test-Roller Abrasion

The wear rate of the coating is determined using an abrasion resistance test to stimulate the abrasion to the fixing roll by the paper in the copier. Measure the diameter of the test roller carefully and accurately. The test roller is mounted to the rotating structure. A 2.25 inch (5.7 cm) wide standard paper cash register tape is pressed onto the roller by applying a 610 g weight to the paper along a 0.25 inch (0.64 cm) contact path. The roller rotates at 60 rpm. After every 10 turns, the paper tape moves 0.29 inches (0.74 cm) to add new paper to the surface to be worn. The temperature is room temperature of approximately 75 ° F. (24 ° C.), air conditioned. After 10,000 cycles or when the substrate begins to appear, stop the test and record the revolutions. Measure the diameter of the roller in the worn area. The wear rate is calculated in cycles per wear micron.

Abrasion Test -Reciprocating Arm Abrasion Test

The film structure is tested using a reciprocating arm wear tester (available from Byk Gardner, Columbia, MD) and nylon brush (WA 2262, also available from Byk Gardner). After the film is placed under 0 and 50 cycles of the abrasion tester, the 60 degree gloss of the film is measured using a micro-TRI-gloss meter available with Byk Gardner according to ASTM method D523. One cycle is a reciprocating motion from brush to brush. The film is evaluated for gloss loss.

Peel test

Peeling of the coating composition on a fixing roll was tested in a commercial copier, Ricoh AF 350. The coating was judged by the number of copies produced without toner contamination. Toner contamination is the result of inferior peeling of the toner from the fixing roll so that the toner accumulates on the roll to form inferior quality copies.

In the examples below, the substrates for the coating were baked for 30 minutes at 800 ° F. (427 ° C.) and washed by grit blasting with 40 grit aluminum oxide to a hardness of approximately 70-125 microinches Ra. The liquid coating was applied by using a spray gun of model number MSA-510 from DeVilbiss, Glendal Heights, Illinois.

For Examples 1 and 2, the primer layer was applied to a rotating wafer steel specimen and then baked at 66 ° C. for 5 minutes. Rotating wafer structures are specified in ASTM D3072. The dry film thickness (DFT) of the primer layer was about 10 μm. The overcoat was applied twice and then baked at 66 ° C. for 5 minutes and then at 149 ° C. for 10 minutes. Finally, the coated disks were baked at 399 ° C. for 5 minutes. The total dry film thickness (DFT) of the coating was approximately 100 μm. This coated specimen was tested by the thrust abrasion weight loss method.

The primers used in the examples have the following pre-bake compositions.

Table 1-Liquid Primers ingredient weight% Fluoropolymer PTFE dispersion 12.8 PFA dispersion 8.8 FEP dispersion 9.5 Polymer binder Polyamideimide 4.6 Colloidal silica 2.9 menstruum water 50.4 Other organics * 7.3 Pigment 3.4 Dispersant 0.3 sum 100 Other organics may include solvents such as N-methyl-2-pyrrolidone, MIBK (methyl isobutyl ketone), hydrocarbons such as heavy naphtha, xylene, etc., furfuryl alcohol, triethanol amine or mixtures thereof Can be. PTFE dispersion: 59-61% solid PTFE, particle size 170-210 nm, melting point (first) 337 ° C, (second) 317 ° C PFA dispersion: 58-62% solid PFA, particle size 185-245 nm, PPVE content 2.9-3.6 wt%, MFR 1.3-2.7 g / 10 min @ 372 ° C FEP dispersion: 54.5-55.5% solids FEP, particle size 160-220 nm, HFP content 9.3-12.4 wt%, MFR 11.8-21.3 g / 10 min @ 372 ℃

Example  One- Fluoropolymer  And wear resistance of fine pulp

A series of wafer substrates washed and coated with primers was prepared as above. The overcoat was applied to the primed substrate. The overcoat formed in Example 1 had a composition as shown in Table 2 below. The micropulp filling ratio was varied in the range of 0% to 4.0% by weight in the dry film. Four types of micropulp fibers with varying median volume average lengths (8, 20, 31 and 112) were tested and the test results were specified. Fiber length was determined by laser diffraction and the measured value approximated the volume average length described above. The abrasion test results for the samples tested by the thrust abrasion weight loss method described above are shown in Table 4 below for different micropulp fills and fiber lengths.

Table 2-Composition Modified by Micropulp % By weight of filling pulp in dry film 0.0 0.25 0.50 1.0 2.0 3.0 4.0 Fluoropolymer weight% weight% weight% weight% weight% weight% weight% PFA dispersion 37.9 37.9 37.9 37.9 37.9 37.9 37.9 PFA Powder 12.3 12.3 12.3 12.3 12.3 12.3 12.3 Fine Pulp *** 0.00 0.0929 0.186 0.374 0.757 1.15 1.55 menstruum water 24.5 24.4 24.3 24.1 23.7 23.3 22.9 Other organics * 17.4 17.4 17.4 17.4 17.4 17.4 17.4 Supplements Conductive mica 1.89 1.89 1.89 1.89 1.89 1.89 1.89 Other Supplements ** 0.203 0.203 0.203 0.203 0.203 0.203 0.203 Dispersant 5.49 5.49 5.49 5.49 5.49 5.49 5.49 sum 100 100 100 100 100 100 100 Other organics may include solvents such as N-methyl-2-pyrrolidone, diethylene glycol monobutyl ether, hydrocarbons such as heavy naphtha, xylene and the like, oleic acid, triethanol amine or mixtures thereof. ** Other adjuvants include non-conductive mica, carbon black. *** Fine pulp and water are combined into the dispersion. The median volume average length of the micropulps used in this experiment is shown in Table 3 below. PFA dispersion: 58-62% solid PFA, particle size 185-245 nm, PPVE content 2.9-3.6 wt%, MFR 1.3-2.7 g / 10 min @ 372 ° C. PFA powder: TFE / PPVE fluoropolymer resin containing 3.5-4.6 wt% PPVE having a melt flow rate of 9.7-17.7 g / 10 min and an average particle size of 20 μm.

Table 3- Volume Average Length of Fine Pulp Sample  Medium volume average length (μm) One 112 2 31 3 20 4 8

Table 4-Trust Abrasion Test Results (Micropulp)  Wear index (cycles per 1 mg wear) % By weight of filling pulp in dry film 0 (control) 0.25 0.50 1.0 2.0 3.0 4.0 Medium volume average length (μm) 112 260 570 530 700 830 790 770 31 260 390 430 650 880 880 940 20 260 510 610 770 1250 1250 1200 8 260 430 650 880 1300 1200 1100

Example  2 - Fluoropolymer , Fine pulp and UMB Wear resistance

A series of wafer substrates washed and coated with primers was prepared as above. The overcoat was applied to the primed substrate. The overcoat formed in Example 2 had a composition as shown in Table 5 below. The micropulp filling ratio was kept constant at 2% by weight in the dry film. The micropulp had a median volume average length of 8 μm. The ultramarine (UMB) fill ratio was varied to 0%, 8% and 12% by weight in the dry film. The abrasion test results for the samples tested by the thrust abrasion weight loss method are shown in Table 6 below for the different ultramarine fill ratios.

Table 5-Overcoat Modified by Micropulp and UMB Ultramarine Filling Ratio Weight% in Dry Film 0.0 8.0 12.0 % By weight of filling pulp in dry film 2.0 2.0 2.0 Fluoropolymer weight% weight% weight% PFA dispersion 37.9 37.9 37.9 PFA Powder 12.3 12.3 12.3 Fine pulp Sample 4 ** 0.757 0.824 0.862 menstruum water 23.7 20.4 18.5 Organic matter 17.4 17.4 17.4 Supplements Conductive mica 1.89 1.89 1.89 County Office 0.00 3.30 5.17 Other supplements 0.203 0.203 0.203 Dispersant 5.49 5.49 5.49 sum 100 100 100 ** Micropulp Sample 4: 8 μm Medium Volume Average Length

Table 6-Trust Abrasion Test Results (Micropulp and UMB) Ultramarine Filling Ratio Weight% in Dry Film 0 (control) 8.0 12.0 Medium volume average length (μm) 8 1300 3300 4300

The overcoat layers formed in Examples A, 3 and 4 below have the following pre-baking compositions.

Table 7-Overcoat Compositions for Examples A, 3, and 4 ingredient A 3 4 Control UMB UMB and Fine Pulp weight% weight% weight% Fluoropolymer PFA dispersion 37.9 36.3 36.3 PFA Powder 12.3 11.7 11.7 Aramid Fiber Fine Pulp *** - - 0.3 menstruum water 24.8 25.7 25.3 Other organics * 17.4 16.7 16.7 Supplements Conductive mica 1.9 1.8 1.8 County Office - 2.4 2.5 Other Supplements ** 0.2 - - Dispersant 5.5 5.4 5.4 sum 100 100 100 Other organics may include solvents such as N-methyl-2-pyrrolidone, diethylene glycol monobutyl ether, hydrocarbons such as heavy naphtha, xylene and the like, oleic acid, triethanol amine or mixtures thereof. ** Other pigments include non-conductive mica, carbon black. *** Aramid fibers and water are combined into a dispersion and the fiber median volume average length is 108 μm. PFA dispersion: 58-62% solid PFA, particle size 185-245 nm, PPVE content 2.9-3.6 wt%, MFR 1.3-2.7 g / 10 min @ 372 ° C. PFA powder: TFE / PPVE fluoropolymer resin containing 3.5-4.6 wt% PPVE having a melt flow rate of 9.7-17.7 g / 10 min and an average particle size of 20 μm.

Comparative example  A-control coating

The primer layer was applied to an aluminum test roller (10.5 in, 26.7 cm long; 1.125 in, 2.9 cm diameter) as described above, and then baked at 150 ° C. for 5 minutes. The dry film thickness (DFT) of the primer layer was 8-12 μm. Overcoat A containing no ultramarine blue and fine pulp was applied and then baked at 800 ° F. (427 ° C.) for 10 minutes. The total dry film thickness (DFT) of the coating was 35-45 μm. This coating provided 1068 cycles / micron wear when tested by the roller wear test described above. The above peeling test was carried out by testing the coating with a commercial copier, Ricoh AF 350. Coating wear caused toner contamination after about 35,000 copies.

Example 3-Navy Office ( UMB ) transform

The primer layer was applied to an aluminum test roller (10.5 in, 26.7 cm long; 1.125 in, 2.9 cm diameter) as described above, and then baked at 150 ° C. for 5 minutes. The dry film thickness (DFT) of the primer layer was 8-12 μm. Overcoat 2 containing ultramarine blue was applied and then baked at 800 ° F. (427 ° C.) for 10 minutes. The total dry film thickness (DFT) of the coating was 35-45 μm. This coating provided 3814 cycles / micron wear when tested by the roller wear test described above. The above peeling test was carried out by testing the coating with a commercial copier, Ricoh AF 350. Toner contamination occurred after about 50,000 copies due to coating wear.

Example  4 - Aramid  Fiber with fine pulp UMB

The primer layer was applied to an aluminum test roller (10.5 in, 26.7 cm long; 1.125 in, 2.9 cm diameter) as described above, and then baked at 150 ° C. for 5 minutes. The dry film thickness (DFT) of the primer layer was 8-12 μm. Overcoat 4 containing ultramarine blue (UMB) and aramid fiber micropulp with a median volume average length of 108 μm was applied and then baked at 800 ° F. (427 ° C.) for 10 minutes. The total dry film thickness (DFT) of the coating was 35-45 μm. This coating provided 6500 cycles / micron wear when tested by the roller wear test described above. The surface of this coating could be honed to a smooth surface, generally free of topography, to improve peel properties. The above peeling test was carried out by testing the coating with a commercial copier, Ricoh AF 350. The test was stopped after about 150,000 copies. Less picker finger wear was observed than the roller produced by Control Example A, and there was no toner contamination.

Table 8-Summary of Roller Wear Test Results A 3 4 Control UMB UMB and Fine Pulp UMB wt%, dry film 0 6.4 7.4 % Fine pulp, dry film 0 0 1.0 Micron per cycle 1100 3800 6500

Example  5- PVF  Out of film Aramid  Fiber fine pulp

Propylene carbonate prepared by grinding 40 parts of PVF and 60 parts of propylene carbonate in a 1 mm glass medium using a model LMJ 2 mill (available from Netzsch Inc., Exton, PA). Film A was prepared from a homogeneous dispersion of polyvinyl vinyl fluoride (PVF) in. With the help of a 5-mil (125 μm) doctor bleed, an electric oven is added to the glass and a volatilize propylene carbonate to coalesce the PVF film (Hotpack, Philadelphia, PA). Baking at 180 ° C. for 5 minutes. The nominal 1 mil (25 μm) thick self supporting film A was removed from the glass.

Films from the same homogeneous mixture of PVF in propylene carbonate, using an air propeller to add a dispersion of aramid fiber micropulp in Essex N-methyl pyrrolidone (NMP) to give a uniform mixture. B, C, D, E, F and G were prepared. The median volume average length of the fibers in each film and the amount of micropulp are shown in Table 9 below.

The films B, C, D, E were lowered on glass using a 5-mil (125 μm) doctor bled and baked in an electric oven (Hotpack, Philadelphia, Penn.) At 180 ° C. for 5 minutes. The resulting self supporting film was nominally 1 mil (25 μm) thick and was removed from the glass.

Using flat plate presses (Wabash, Wabash, Indiana), films A, B, C, D and E were pressed onto a black ABS sheet, and a reciprocating arm abrasion tester (Bik, Columbia, MD) Abrasion tests were performed using Gardner) and nylon brushes (WA 2262, also available from Gardner). As above, using ASTM D523, 60 degree gloss measurements were obtained after 0, 50 cycles, where one cycle is a reciprocating motion of the brush. The film was evaluated for gloss retention. Films D and E with 1% by weight (dry weight) of aramid micropulp retained gloss retention (86%) of film A without micropulp and gloss retention of films B and C containing 0.25% by weight micropulp Abrasion resistance is markedly improved, as evidenced by high (94% or higher) gloss retention compared to (84-86%). In view of the less gloss reduction of film E (5 units) compared to the much less gloss reduction of film E (11 units), the wear resistance improvement by this test exceeds 100%. These results showed that the wear resistance was improved regardless of the fiber length.

Table 9-PVF with Fine Pulp Film A Film B Film C Film D Film E Film F Film G ingredient (Control) (Control) Micropulp * Weight% Dry Film (Medium Volume Average Length 62.1) 0 0.25 0 1.0 0 0 0 Micropulp Weight% Dry Film (Medium Volume Average Length 7.5) 0 0 0.25 0 1.0 0 0 Micropulp Weight% Dry Film (Medium Volume Average Length 19.4) 0 0 0 0 0 0 0.5 * NMP dispersion

Table 10-Reciprocating Arm Wear Test Summary Cycle 0 50  60 degree polished Film A 80 69 Film B 79 66 Film C 79 68 Film D 80 76 Film E 80 75

Films F and G were lowered from the glass and baked in an electric oven (Hotpack, Philadelphia, PA) for 5 minutes at 180 ° C. as described above using a 7-mil doctor bled (178 μm). The resulting self supporting film was nominally 1.5 mils (38 microns) thick and was removed from the glass. The toughness of the films was compared using ASTM D636 (Instron Model 1011, Canton, Mass.). Both Film F and Film G were measured to have a tensile strength of 5400 lbf / square inch. However, the elongation of the film G containing 0.5% by weight of aramid micropulp was 165%, while the elongation of the film F containing no aramid micropulp was 58%. High elongation is surprisingly much tougher than fluoropolymer films of known quality, with films with aramid micropulps, thin and tough for many aircraft interior applications that require lightweight films that exhibit excellent flame resistance and produce less smoke. It suggests that this high film can be used.

Claims (19)

A composition comprising a fluoropolymer and an effective amount of micropulp, wherein the wear resistance of the surface of the article formed from the composition is increased by at least 25% relative to the surface of the article formed from the fluoropolymer alone. The composition of claim 1, wherein the wear resistance of the surface of the article formed from the composition comprising the fluoropolymer and an effective amount of micropulp is increased by at least 50% relative to the surface of the article formed from the fluoropolymer alone. The composition of claim 1 wherein said micropulp is an aromatic polyamide. The composition of claim 1 wherein the fluoropolymer is melt processable or non melt processable. 4. The composition of claim 3, wherein the aromatic polyamide is poly (p-phenylene terephthalamide) or poly (m-phenylene isophthalamide) or mixtures thereof. The composition of claim 1, wherein said article is a film. The composition of claim 6 further comprising an effective amount of an electrically conductive particulate material. 8. The composition of claim 7, wherein said electroconductive particulate material is mica coated with an electroconductive material. The composition of claim 6, further comprising an effective amount of pigment to further increase the wear resistance of the film formed from the composition as compared to the film formed from the fluoropolymer alone. The composition of claim 9 wherein said pigment is a zeolite. The composition of claim 6 containing both the electroconductive particulate material and the pigment. The method of claim 11, wherein the total amount of the micropulp, the electrically conductive particulate material and the pigment is at least 5% by weight based on the total weight of these components and the fluoropolymer, and the wear resistance increase is at least 50% compared to the fluoropolymer alone. Wherein the peeling of the film is characterized in that the copier toner does not adhere to the film when the film is used as a film coating on a fuser roll. The composition of claim 1, wherein the micropulp is characterized by a volume average fiber length of 0.01 to 125 μm. The composition of claim 1 wherein the micropulp is characterized by a volume average fiber length of 5 to 30 μm. The composition of claim 6, wherein the film is on a fixing roll. The composition of claim 1 dispersed in a liquid medium. The composition of claim 1 in the form of a powder. A film of the composition of claim 1. 18. The film of claim 17 as a film coating on a fixing roll.