JP3366643B2 - Fibrillated surface - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to porous polytetrafluoroethylene structures having a fibrillated surface. It is particularly, but not exclusively, useful as an oil transfer component that applies release oil to the fuser roll of a copier and / or wipes excess toner from or from another roll in contact with it. Can be

As used herein, the term "copying machine"
Relates to equipment using heated fuser rolls, such as plain paper copiers and laser printers.

2. Description of the Related Art In a plain paper copying machine, a toner image formed on the surface of paper or other recording medium is fixed by the application of heat and pressure. In some plain paper copiers, fusing is accomplished by passing an image bearing recording medium between a hot fusing roll and a pressure roll. If this type of fusing device is used, the toner material will be in direct contact with the roll surface and some of the toner will normally adhere to the roll surface. On the next rotation of the roll, the adhered toner material redeposits on the recording medium, causing undesired offset images, stains,
May cause dirt or, in severe cases,
The recording medium may adhere to the adhered toner material on the roll and wrap around the roll.

To address this problem, materials with good release properties, such as silicone rubber and polytetrafluoroethylene, are often used on the roll surface. Although the performance of thermal fusing devices is improved, the use of silicone rubber or polytetrafluoroethylene roll surfaces alone does not eliminate the problem. Another approach is to include a release agent in the toner material, which prevents the toner material from adhering to the roll surface. These oilless toners improve the performance of thermal fusing devices, but again do not completely eliminate the problems associated with picking up and moving toner, especially for high speed copiers.

Toner pick-up by the roll can be controlled by coating at least one surface of the roll with a liquid release agent such as silicone oil. It is important that the stripping solution is applied to the roll surface uniformly and in an accurate amount. Too little liquid or uneven surface coverage does not prevent toner from picking up from the paper and depositing on the roll. On the other hand, an excessive amount of stripper may blister the wrinkle surface of the silicone rubber and cause it to wrinkle, resulting in unacceptable quality copies.

Japanese Unexamined Patent Publication No. 62-178992 discloses a device for uniformly measuring and coating a release liquid on the roll surface of a copying machine. These devices consist of an oil permeation control layer adhered to a thick porous material that serves as a wick or reservoir for supplying oil to the permeation control layer. The permeation control layer is typically a film of porous polytetrafluoroethylene that has been impregnated with a compound of silicone oil and silicone rubber and then heat treated to crosslink the silicone rubber. The thick porous material to which the permeation control layer is adhered is typically a porous thermosetting resin foam,
Alternatively, it is felt of Nomex (trademark) fiber, glass fiber, carbon fiber, polytetrafluoroethylene fiber or other heat resistant fiber. The fiber connected under the trademark Nomex is an aramid fiber, a type of polyamide.

Conventional plain paper copiers, which use silicone oil as a liquid release agent, generally provide a means for coating the fuser roll with the silicone oil, as well as unwanted adhering toner, paper dust and other undesirable materials. Includes means for wiping the roll for removal. Often, the coating and wiping actions are performed by a single device. Placed on top of a reservoir wick on a particular type of device,
A reservoir wick, usually made of Nomex felt, is provided with a cover wick to meter the oil flow from the reservoir wick to the fuser roll and to provide improved wear and distribution characteristics. This cover wick is typically Nomex fabric. However, this cover wick has been found to have only a limited life and typically withstands about 60,000 copies before it needs replacement. It would be desirable to have a cover wick that lasts as long as the life of the fuser roll.

In another conventional type of copier, the oil coating and wiping action is typically provided by a length of felt made of Nomex or polytetrafluoroethylene fibers. Rolls are typically 435m wide
m × length 1.4 m. While the machine is making a copy, the silicone oil-loaded roll passes over the fuser roll at a rate of about 2 cm / hr. This oiling roll provides silicone oil. Further, the excess toner washed from the fuser roll is picked up, adheres to the oiling roll, and is carried away. Typically, oiling roll felt has a weight of 700 g / m ² and a thickness of 1.3 mm. Due to the physical constraints of the copier, this limits the length of material on the oiling roll to about 1.4 m. Generally speaking, it is not possible to make a satisfactory felt weight of less than 700 g / m ² for this purpose. Therefore, as a practical matter, it is necessary to replace the oiling roll after every 10 days of operation.

British Published Patent Application No. 2242431 (9106768.6) discloses a porous polytetrafluoroethylene structure for use as a filter in industrial filtration. The porous polytetrafluoroethylene material is made by fusing particles of polytetrafluoroethylene in such a way as to form a porous, unitary network of interconnected particles. The disclosure of this patent specification is incorporated herein. This specification is particularly relevant to the filtration of aqueous slurries.

Applicant's International Patent Application WO 93/08512 discloses such porous PTFE material as an oil transfer component of a copier, in particular controlling the amount of release oil supplied to the fuser roll and excess toner therefrom. For use as an oil permeation control layer for wiping off oil.

SUMMARY OF THE INVENTION Currently, surprisingly, the properties of porous PTFE structures are
It has been found that this can be improved by providing a fibrillated surface thereon.

Thus, one aspect of the present invention is formed from particles of granular-type polytetrafluoroethylene fused together to form a porous integral network of interconnected particles. And a porous polytetrafluoroethylene (PTFE) structure.

Generally speaking, the present invention is directed to UK Published Patent Application No. 2242 for use as an oil transfer component for coating or wiping the fuser roll of a copier.
Keeping in mind the use of porous polytetrafluoroethylene materials as disclosed in US Pat. This material can withstand the high temperatures encountered (around 200 ° C.) and has excellent mechanical properties and durability in this application.

Another aspect of the present invention provides an oil transfer component for coating or wiping a roll of a fuser device of a copier, the oil transfer component being a porous integral unit of interconnected particles. Includes a porous polytetrafluoroethylene structure formed from particles of particulate polytetrafluoroethylene fused together to form a network for contacting the fuser device roll during use. Has a surface of which the surface is fibrillated.

Porous polytetrafluoroethylene (PTFE) structures, in general, for the purpose of acting as oil transfer components,
Supporting means may be provided for supporting the structure in the copier. In the case of so-called coverwicks, the support means may be in the form of a frame or a pair of parallel rods extending along one side of the strip of coverwicks. Alternatively, the porous polytetrafluoroethylene structure may be laminated to the reservoir material used as the support structure. Further, the porous polytetrafluoroethylene structure may be provided in the form of a continuous web, or an oil reservoir material optionally covered with a felt cover (e.g., the foam disclosed in JP-A-62-178992). It may be applied on a roll made of porous ceramic). In general, the porous polytetrafluoroethylene structure is in the form of a sheet material, generally having a thickness in the range 50 to 1500 μm, especially 100 to 1000 μm.

The porous polytetrafluoroethylene structure is hydrophobic but has a high affinity for liquid release agents such as silicone oil. The oil transfer component is generally
The release oil can be provided pre-loaded.
In oil-filled molds, the components are discarded when the oil is substantially used up. In the oil supply type, the fuser oil is supplied to it by an oil supply mechanism. Typically, this oil is 10-50% by weight of the PTFE structure of the oil transfer component,
In particular, it can constitute 20-40% by weight. To provide such oil-holding capacity, the porous polytetrafluoroethylene structure is typically 0.5-1.8, such as 0.6-1.5, typically 0.
It has a specific gravity of 7 to 1.2. Pure non-porous PT for comparison
FE typically has a specific gravity of 2.16.

Preferably, the porous polytetrafluoroethylene structures do not contain any filler material, because they are generally of inorganic origin and tend to be abrasive, which damages the fuser roll.

According to the invention, this structure has a fibrillated surface. This means that the PTFE elongated fibrils extend from the surface of the structure. Fibrils generally range in length to 2 mm, in particular 1 mm in length, in particular 0.5 mm in length. If the fibrils are too long, there is an increased risk of the fibrils detaching from the surface of the structure during use. On the other hand, if they are too short, their coating and wiping ability may be compromised. Length 0.1
A fibril length of ~ 0.5 mm is preferred. The length of each fibril is generally 1 to 10 times its lateral dimension.

Generally, fibrils are created by tearing the surface of a PTFE structure. This fibril is PT
It has an integral form with the FE structure, and therefore the PT as a whole.
It is firmly fixed in the FE structure.

Here, in a preferred embodiment, first, the porous PTFE structure is mechanically prepared so that when the PTFE structure is separated from the substrate, the PTFE structure is torn and pulled out from the fibril surface. Bond to a substrate having an irregular surface to bond. The surface of the substrate is a specific surface shape (surface, ridge, valley, score, protrusion, etc.).
features) can be provided and these can be regular or irregular patterns. In general,
Certain surface features have steep sides or undercut portions to help mechanically secure the PTFE to the structure.

It has been found that a particularly useful substrate is preferably stainless steel wire mesh. Generally, this wire mesh has 15 to 75 wire rods per inch in one direction (each wire rod has 1.5 to 75
Thickness of 0.3 mm) and 75 to 400 wire rods (inch thickness of 0.3 to 0.07 mm) per inch in the perpendicular direction. The openings of this mesh can range from 40 to 150 μm across. Also, cloth can be used instead of the wire mesh,
However, the fabric must have adequate mechanical strength to be removed from the PTFE structure.

For optimal fibrillation, at least a portion of the wire of the wire mesh should be buried with PTFE, forcing the wire away from the PTFE upon removal. If the wire mesh has a thin wire and a thick wire, only the thin wire is PT.
It is preferably buried in FE.

The PTFE can be deformed (eg, between embossing rollers) to come into intimate contact with the substrate, but preferably PTFE
The structure consists of granular PTFE particles in a liquid vehicle that is sprayed or otherwise placed on the substrate prior to fusing the particles.

When PTFE is removed from the substrate, the surface shape of the substrate is
It can be totally converted to fibrils on a PTFE surface. Here, in a preferred embodiment, the PTFE surface has an overall surface texture in addition to the fibrils.
(As disclosed in the applicant's international patent application WO93 / 08512). In the case of wire mesh substrates, this would be obvious as an overall pattern of grooves and ridges on the PTFE surface whose surface is then fibrillated. This particular combination of surface topography has been found to be particularly beneficial in coating and wiping rolls in fuser devices.

The porous polytetrafluoroethylene structure of the present invention provides superior wear properties compared to conventional materials and does not drop fibers. For continuous webs, this porous polytetrafluoroethylene structure can be provided much thinner than conventional felt at a given oil holding capacity, which maintains the same oiling and wiping properties. While allowing a much longer period to be used. Also, there are few obstacles on the roller due to wear.

Porous polytetrafluoroethylene structures can be prepared as disclosed in British Published Patent Application No. 2242431. It is particularly preferred to make the structure from a mixture of particles of different grades of polytetrafluoroethylene of the granular type. As is well known, PTFE is manufactured from two different types of so-called "granular PTFE" and so-called "fine powder PTFE". These materials have completely different properties and the present invention relates to the former. Particularly useful products for use in the present invention include 40-60% of Teflon resin grade 7A and 40-60% of Teflon resin grade 9B. For continuous webs, the content of grade 7A may be increased up to 100%.
Teflon resin grades 7A and 9B are available from DuPont Specialty Polymers Division in Wilmington, USA. Porous polytetrafluoroethylene structures are usually prepared by spraying onto substrates such as ceramic tiles or metal sheets.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, embodiments of the present invention will be described, but these are only examples.

The accompanying drawings show various fuser roll arrangements for use in copiers to which the present invention can be applied.

FIG. 1 is a schematic elevational view of the fuser portion of a plain paper copier in which release oil is applied by an oil transfer component in the form of an oil-filled continuous web in accordance with the present invention and wipes off excess toner.

FIG. 2 is a schematic elevational view of the fuser portion of a plain paper copier in which release oil is applied to a continuous web according to the invention by an oil supply mechanism.

FIG. 3 is a high-level elevational view of the fuser section, in which release oil is applied onto the pressure roll by an oil transfer component in the form of a so-called cover wick.

FIG. 4 is a schematic elevational view of the fuser portion of a laser printer.

FIG. 5 is a schematic elevational view of the fuser portion with the oil transfer component in the form of a roller.

  FIG. 6 shows a cross section through the roller.

FIG. 7 shows a fibrillated porous PTFE according to the present invention.
It is a 400 times optical microscope photograph of the cross section of the structure.

1 and 2 show the fuser portion of a copier that uses a long web to coat and wipe the fuser roll.

FIG. 1 shows a fuser roll 2 covered with PTFE and a pressure roll 4 covered with silicone rubber, which are oiled and wiped by an oil-containing oiling web 6 wound on a spool 8, The web 6 passes around pressure rollers 10 and 12 and is wound on a take-up spool 14.

FIG. 2 shows a similar arrangement, except that oil is applied to the oiling roll or web by the oil supply mechanism 16.

The web was made from a PTFE sheet with a fibrillated surface made as described in Example 1, this example showing 50% PTFE grade 9B and 50% PTFE grade 7A.
Describes the web created from. If a thinner web of higher density is required (eg, for the purpose of rolling a longer length of web on a spool 8 of a given diameter), optionally up to 100% Grade 7A PTFE Grade 7
The proportion of A can be increased. Here, increasing the amount of grade 7A increases the stiffness of the web. The fibrillated surface of the PTFE sheet is placed in contact with the fuser roll 2. This web is filled with silicone release oil before being wound onto spool 8 and is ready for use.

During use, the web slowly advances from spool 8 to take-up spool 14. Release oil is supplied from the oil-filled web and its thin coating is applied to the fuser roll as the fuser roll rotates. The web also wipes excess oil and toner from the fuser roll, which collects on the web. The fibrillated, contoured surface of the web is particularly effective in wiping the fuser roll and preventing unwanted spots of toner from migrating to the copy paper.

In both configurations of Figures 1 and 2, the PTFE web is pre-filled with release oil. Here, in the configuration of FIG.
This oil is boosted by the additional supply of release oil supplied to the web by the normal oil supply mechanism. This allows more release oil to be supplied than can be retained on the web.

Figures 3 and 4 show the sumps filled with peeling oil (26
And 40) shows the use of the fibrillated surface PTFE sheet made in Example 1 as a permeation control layer (22 and 44 respectively) to control the oil supply.

FIG. 3 shows a fuser roll 2 of a PTFE cover and a pressure roll 4 of a silicone rubber cover to which silicone oil is supplied by an oil supply mechanism 16, a reservoir wick 26, and a so-called cover wick 20. The cover wick is supported by a pair of rods 22,24.

In the embodiment of FIG. 3, the reservoir is a felt or open cell foam material (eg, Applicants' international patent application WO93 / 0).
Made of melamine foam as disclosed in 8512 publication and is generally preloaded with release oil. The normal oil supply mechanism 16 supplies additional oil to the sump. In the configuration shown, the cover wick 20 is made of a PTFE sheet with a fibrillated surface as made in Example 1. The fibrillated surface is placed in contact with the roll 4 of silicone cover. In a conventional manner, the cover wick 20 has a pair of seams (not shown) in which a pair of rods 22 and 24 fit to support the wick of the copier.

In use, the release oil is supplied from the reservoir wick 26 and in metered amounts passes through the porous PTFE cover wick to the roll 4 of silicone cover. The peeling oil moves from the roll 4 to the fuser roll 2 while the rolls contact each other and rotate. Excess toner collected on the roll 4 is wiped off by a cover wick 20, which is replaced after a predetermined period of use (or the number of copies made).

FIG. 4 shows the configuration of the laser printer. The oil-containing reservoir 40 made of felt arranged in the channel 42 is made of PTFE.
Oil the fuser roll 2 of the cover. The felt (or open-cell foam) reservoir was laminated to the surface by a speckled pattern of heat resistant adhesive (eg, Dow Corning RTV732), the porous material made in Example 1.
It has a PTFE sheet 44. A PTFE sheet 44 is adhered to the top surface of the reservoir and extends partially down on its sides. The fibrillated surface of the PTFE sheet is placed in contact with the fuser roll 2 during use. In this case, the reservoir is filled with a supply of release oil and the reservoir-PTFE sheet assembly is discarded after a predetermined period of use (or number of copies made). The fibrillated surface serves to supply the fuser roll with release oil and wipe off excess toner, as described above.

FIG. 5 illustrates the use of a roller 30 that coats the fuser roll 2 of the PTFE cover with release oil and wipes off excess toner. The roller was of the oil-filled type comprising a reservoir of felt or open cell foam mounted on a rotating spindle and having an oil permeation control layer of an outer porous PTFE sheet made as in Example 1. Good. The fibrillated surface of the PTFE sheet is placed in contact with the fuser roll.

Alternatively, the roller 30 can be arranged to contact the pressure roller 4 covered with silicone rubber. This roller 30 may be pre-filled with oil,
Alternatively, the oil may be supplied to the center of the roller by an oil supply mechanism.

FIG. 6 is a cross-sectional view of the oil-supplied roller 30, showing its structure. The roller has a hollow metal core 50 that defines an internal void 52 into which silicone release oil is dispensed during use. The core is provided with an open mesh structure (not shown) for supplying silicone oil. An open cell melamine foam (see Applicant's published patent application PCT / GB93 / 00563) sleeve 54 is fitted snugly around the core. This sleeve is made of open-cell polyurethane.
Milled from blocks and slid over the core. An outer layer 56 of porous PTFE sheet material made according to Example 1 is wrapped around a sleeve of melamine foam and made of heat resistant silicone resin (RTV732 from Dow Corning).
Glued to it. The resin is applied along the axisymmetric edges of layer 56 and along the overlapping axially extending edges that form the seam. This resin cures at room temperature. The PTFE sheet is applied with the fibrillated surface outermost.

The roller can also be used as an oil-filled roller by pre-filling release oil through one end of the inner space and then sealing that end.

FIG. 7 is a 400 × optical micrograph of a cross section of a fibrillated PTFE structure according to the present invention. This is unique to a structure made according to Example 1 by depositing PTFE on a stainless steel Panzer weave mesh, for example size (i) of Example 1 below. This optical micrograph shows a view along the direction of the thicker wire of the Panzer weave, where the contour 70 left by the two thicker wires can be seen. Panzer
In the weave, the thicker wires form parallel rows, while the thinner wires run above and below the thicker wire, one thin wire running above a given thicker wire and the next thinner wire. Wire runs below. If PTFE resin enters around the wire (especially thin wire) before heating or curing, PTFE from the net
Removal of the structure results in highly fibrillated portions 72 and regular, specific surface features, or protrusions 74, as a result of tearing of its PTFE as it is removed. The fibrillated portion can have a particular shape like a flat web that aids in toner wiping. If such intrusion is hindered, a low fibrillated PTFE structure with fairly poor toner wiping properties is obtained, as shown in Example 2 below.

The total thickness of the PTFE sheet is about 750 μm, about half (about 350 μm) of which is generally the fibrillated portion.

When viewed in a direction perpendicular to the angle shown in FIG. 7 (ie, along the line of the thinner wire), the protrusions 74 are generally triangular, which means that each thinner wire meets each thicker wire. Corresponding to the triangular voids obtained where a regular surface pattern is formed.

Example 1 (Preparation of PTFE Sheet) (a) Preparation of Unfired Granular PTFE Suspension 250 g of which had been ground to a weight average particle size of about 40 μm
DuPont ™ Granular PTFE Grade 9B (as particle size distribution
99.5% is less than 124 μm, less than 2.8 μm is 0%), 250 g
DuPont Granular PTFE Grade 9A, 13 ml Zonyl ™ FSN surfactant (mixture of nonionic perfluoroalkyl ethoxylates), 10 ml isopropyl alcohol, 41 ml
Pluronic ™ L121 surfactant (polyoxyethylene / polyoxypropylene block copolymer), and 1.14 g of sodium carboxymethyl cellulose (thickener) dissolved in water as a 1% by weight solution in 460 g of water. Add and wear Waring blende
r) for 5 minutes.

(B) Preparation of Porous Granular PTFE Structure The above suspension was sprayed onto a stainless steel wire mesh sheet tack welded onto a stainless steel plate using a Binks BBR spray gun and L88 pressure cup. PT
For the FE suspension, the thick wire rod was not surrounded, but the thin wire rod made of stainless steel wire was generally buried. Air temperature
The temperature was raised to 115 ° C., and when the temperature of the stainless steel plate reached 100 ° C., drying was continued for 30 minutes. The air temperature was then gradually increased to 365 ° C. for several hours. Drying was continued for an additional 2.5 hours once the temperature of the plate reached 350 ° C. The resulting structure was then cooled. Specific gravity is 0.8 g / cc
Met. The following sizes of stainless steel wire mesh were used.

(I) Panzer weave with 132 wires per inch (0.2 mm diameter) / 32 wires per inch (0.45 mm diameter) (80 μm nominal aperture size, obtained from United Wire, Edinburgh, UK) ( ii) 110 wires per inch (0.23mm diameter) / 24 wires per inch (1.06mm diameter) (Bedford, Steer,
Obtained from End and Co. Ltd., St. Helens, United Kingdom) (iii) 250 wires per inch (0.1 mm diameter) / 50 wires per inch (0.51 mm diameter) (Bedford, Steer,
Wire mesh (ii) and (iii) obtained from End and Co. Ltd.
ve) was. After cooling the structure, the PTFE sheet attached to the wire mesh was carefully peeled from the stainless steel wire mesh. The PTFE firmly entered the openings of the wire mesh, and during the process of peeling off the PTFE sheet, the surface of the PTFE was torn and fibrillation occurred. Surface inspection showed irregular fibrils on the torn surface, ranging in length from approximately 0.3 to 0.5 mm depending on the particular wire mesh used. The nominal thickness was 750 μm.

In use, the large ridges of the PTFE surface (corresponding to relatively small and widely spaced wires in the wire mesh) were placed perpendicular to the movement of the PTFE sheet through the fuser roll machine (ie, the direction of web movement). Perpendicular to, or parallel to the axis of the roll).

The PTFE sheet can be used in the form of a continuous web 6 (see Figures 1 and 2), in which case the sheet is
It is wound onto spool 8 with the fibrillated surface outermost so that it is in contact with fuser roll 2.
Larger ridges in the PTFE sheet are arranged to extend across the length of the web to help collect excess toner wiped from fuser roll 2 during use. The PTFE sheet can be made from various proportions of PTFE grades 7A and 7B, as disclosed in GB-A-242431.

In addition, this PTFE sheet is used for the roll 30, the reservoir 26, or the reservoir 40.
Can be used as an oil control layer outside.
A roller structure according to the present invention is shown in FIG.

Example 2 (Comparison Performance) In this example, the PTFE structure of the present invention was compared for its performance in a copier with a comparison PTFE structure having no fibrillated portion.

The PTFE sheet of the present invention was made using a stainless steel panzer weave net, generally as described in Example 1. In this case, the wire mesh was supported in the frame (rather than tack welded onto the plate). The heating time ranged from 2.5 to 6 hours and the overall thickness of the fibrillated PTFE sheet was 600 to 700 μm.

A comparative PTFE sheet without fibrillated portion 72 was made in a similar manner as follows. In the wire mesh
To prevent the PTFE suspension from penetrating, the wire mesh was first sprayed with a solution of carboxymethyl cellulose and then the coating was dried. The coating was sprayed onto the wire mesh in a manner that carboxymethyl cellulose passed through the wire mesh and coated its lower surface. The PTFE suspension was then sprayed from above as described in Example 1. The carboxymethyl cellulose coating is then coated with PTFE.
The suspension creates a barrier against proper end-to-end penetration, and in particular this coating
The suspension greatly prevented the thin wire of the wire mesh from being buried. This considerably reduced the degree of fibrillation of the finished sheet. Next, the PTFE was dried and heated as described above, and the obtained sheet was peeled from the wire mesh.

Siem under the same standard operating conditions to evaluate performance
A continuous web of PTFE sheets was tested on an ensND2 printer (100 copies / min). The configuration is similar to that shown in Figure 2, except that the direction of rotation of the fuser roll is counterclockwise and a doctor blade 80 (shown in dashed lines) is provided between the nip of the web and the roller, Collected all excess toner that was not collected by the web before being transported to the area. The PTFE web is about 0.
Progressed at an average speed of 2 mm / min. The oil supply rate by the oil supply mechanism 16 was constant.

The fibrillated PTFE web of the present invention has been found to efficiently oil fuser roll 2 and satisfactorily remove excess toner from the roll. However, not fibrillated for comparison
The PTFE web did not satisfactorily remove excess toner from the fuser roll, resulting in excess toner accumulating on the doctor blade to the extent that the experiment was stopped prematurely. Thus, the fibrillated PTFE structure of the present invention exhibited superior toner wiping properties as compared to the comparative sheet.

Test and Preparation Method 1) The specific gravity of the PTFE sheet was determined by weighing the sample in two different media, air and water. Weights were measured using an Avery VA124 analytical balance. Specific gravity was calculated as equal to (weight in air) / (weight in air-weight in water).

2) Teflon ™ granular type PTFE fluorocarbon resins grades 7A and 9B are available from DuPont Specialty Polymers Division in Wilmington, USA. Grade 9B is a pre-melted fired resin. The manufacturer's product specifications are an average specific gravity of 2.16 and an average particle size of 35.
μm (Grade 7A) and 500 μm (Grade 9 before fine grinding)
B) is shown. PTFE grade 7A is unfired,
Used as supplied.

Prior to use, PTFE grade 9B was milled to a weight average particle size of about 40 μm by milling its aqueous slurry between grinding stones at room temperature as follows.

PTFE grade 9B is mixed with water to form a slurry, which slurry is fed between the closely spaced grinding surfaces of a grinding roll as disclosed in U.S. Pat.
The FE pieces were crushed and sheared into particles. The milled slurry was then filtered or centrifuged to separate expanded PTFE particles from water and the separated finely ground particles were oven dried at 125-150 ° C.

3) The particle size of crushed PTFE grade 9B was measured as follows. Using a magnetic stirrer and ultrasonic agitation, 2.5 g of crushed PTFE powder was dispersed in 60 ml of isopropyl alcohol (Ultrasonic probe W-385 manufactured by Heat Systems Ultrasonics).
Type).

A 4-6 ml aliquot of the dispersed particles was taken for analysis by Lea.
d & Northup Microtrac FRA Particle size analyzer was added to about 150 ml of circulating isopropyl alcohol in the analyzer. For each analysis, the sample circulation speed was 2 liters / minute, and the operation was performed 3 times for 30 seconds, during which the light scattered by the dispersed particles was automatically measured, and the particle size distribution was automatically calculated from the measured values. Calculated to.

Front Page Continuation (72) Inventor McCollum, Francis Michael Jon, Leven Kewai 86 UK, Landin Links, Leven Road 68 (56) References JP 57-126631 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) C08J 9/00 WPI / L (QUESTEL)

Claims (26)

(57) [Claims] 1. A porous monolithic network of interconnected particles formed on a substrate comprising particulate polytetrafluoroethylene particles fused together and fibrillated by tearing from said substrate. A porous polytetrafluoroethylene (PTFE) structure having a modified (72) surface. 2. Structure according to claim 1, in which the fibrils (72) have a length of up to 1 mm. 3. A structure according to claim 1, wherein the fibrils (72) have a length of up to 0.5 mm. 4. Structure according to any one of the preceding claims, in which the fibrillated surface further comprises an overall pattern of regular, specific surface features (74). 5. The structure according to claim 4, wherein the surface shape is selected from a ridge, a groove, a protrusion, or a notch. 6. A structure according to claim 5, wherein the protrusion (74) has a substantially triangular shape. 7. The structure according to claim 5, wherein the fibrillated surface has a wire mesh pattern. 8. An oil transfer component for coating or wiping a roll (2) of a fuser device of a copier, comprising the porous polytetrafluoroethylene structure of claim 1 and the structure. Is an oil transfer component having a surface which, in use, contacts the roll of the fuser device, the surface being fibrillated (72). 9. Porous polytetrafluoroethylene is 0.5
9. A component according to claim 8 having a specific gravity of ˜1.8. 10. Porous polytetrafluoroethylene is 0.
A component according to claim 9 having a specific gravity of 7 to 1.2. 11. A porous polytetrafluoroethylene,
The constituent part according to any one of claims 8 to 10, which does not include a filler material derived from an inorganic substance. 12. A component according to any one of claims 8 to 11 in which the polytetrafluoroethylene component is made by spray deposition. 13. Component according to any one of claims 8 to 12, wherein the porous polytetrafluoroethylene structure is in the form of a sheet material. 14. The component of claim 13 in which the polytetrafluoroethylene sheet material is laminated to a woven or non-woven backing. 15. A component according to claim 13 or 14, wherein the polytetrafluoroethylene sheet material has a thickness of 50 to 1500 μm. 16. The invention according to claim 8, which is pre-filled with oil.
Item 15. A constituent part according to any one of items 15 to 15. 17. A component according to claim 16 wherein the release oil comprises 10 to 50% by weight of the component. 18. Component according to any one of claims 8 to 17, in the form of a roll (6) of sheet material. 19. Component according to any one of claims 8 to 17, in the form of a cover wick (20). 20. Component according to any one of claims 8 to 17, in the form of a roller (30) having an outer layer of porous polytetrafluoroethylene material. 21. Component according to any one of claims 8 to 17, comprising an oil sump material (40) laminated with a porous polytetrafluoroethylene material (44). 22. A porous polytetrafluoroethylene (PTFE) structure according to claim 1, wherein the fibrillated surface of the porous polytetrafluoroethylene structure is contacted with a roll of a fuser device of a copying machine. And the porous polytetrafluoroethylene structure is operated to coat the roll with oil and / or to operate the copier so that it is effective in wiping excess oil or toner from the roll. A method of coating or wiping a roll of a fuser unit of a copying machine. 23. A substrate having a particular surface profile is provided with particulate polytetrafluoroethylene particles, the particles are fused and mechanically bonded to the substrate of the particular surface profile, interconnected. Creating a structure in the form of a porous, monolithic network of particles and removing the structure from its substrate, thereby forming a fibrillated surface of the polytetrafluoroethylene structure, A method for producing a porous polytetrafluoroethylene (PTFE) structure having a fibrillated surface. 24. The method according to claim 23, wherein the base material is a woven net.
The method described in the section. 25. The method according to claim 24, wherein the mesh has a structure including a thin wire and a thick wire. 26. The method of claim 24, wherein the fused polytetrafluoroethylene structure bonded to the net of the substrate substantially immerses the fine wire of the net.