KR20010031022A - Abrasive Articles and Their Preparations - Google Patents

Abstract

The invention relates to an abrasive fabric wherein there is a discontinuous region of metal deposited on or through the fabric, the abrasive comprising the fabric,

Adhesive layer and

Backing equipment

Wherein the abrasive fabric is adhered to the backing substrate by an adhesive layer,

i) the surface of the abrasive fabric adhered to the backing is roughened by polishing or the like, or ii) the adhesive layer comprises an epoxy-acrylate thermosetting adhesive.

Description

Abrasive Articles and Their Preparation {Abrasive Articles and Their Preparations}

The present invention relates to an abrasive article and a method of making the same. In particular, the present invention relates to a textile article and an abrasive article of the type which comprises a discontinuous region of electrodeposited metal present on or through the textile material and supported by the textile material and in which the abrasive is embedded in the metal.

Methods of making electrodeposited abrasive layers through fabric materials are known in the art and described in, for example, British Patent No. 2 200 920, European Patent No. 13486, US Patent No. 4,256,467, and the like. have. Typically, the abrasive layer is formed by placing a fabric, such as a woven or nonwoven mesh material, on an electrically conductive surface and electrodepositing the metal on the fabric material in the presence of abrasive minerals to cause the mineral to be embedded in the metal. The insulating material is optionally applied to the fabric material or the electrically conductive surface prior to depositing the metal layer, so that the metal is deposited only on the fabric in areas not covered with the insulating material, thereby determining the pattern of the abrasive surface.

In one method of making the electrodeposited abrasive layer, an insulated material in the form of an ink is screen printed onto a mesh material in the form of a woven fabric of an electrically insulating material such as nylon, cotton, terylene, or the like. These inks are usually waterproof and acid resistant, and the preferred form is that the color does not change even when the working temperature of the abrasive article is high, for example up to approximately 220 ° C. This ink must be compatible with any hot-melt adhesive that can subsequently be applied to the polishing layer to secure the polishing layer to the backing material. This ink may be a resin-based or oil-based ink, and colored ink may also be used if desired.

Screen printing can be done with conventional screen printing techniques through a method whereby discontinuous areas free of insulating material remain, where ink penetrates and is absorbed into defined areas of the fabric material to determine the polishing surface. Such discontinuous areas can be any convenient shape and size, such as round, diamond-shaped, rectangular, and the like.

Alternatively, an electrically insulating mask is applied to an electrically conductive surface, such as a stainless steel drum, and the fabric material is placed on the electrically conductive surface, followed by electrodeposition of the metal through the fabric material in the presence of the abrasive to discontinue the metal embedded with the abrasive. Provides a realm.

Alternatively, the ink can be mixed with the adhesive and screen printed onto the fabric material. As described above, the metal is deposited and the polishing layer is heated to melt the adhesive component of the insulating material, thereby attaching the obtained polishing layer to the backing material so that the backing material adheres to the polishing layer.

Alternatively, the insulating material may use only the adhesive as the insulating material, not the ink or the mixture of the ink and the adhesive. In this case, the adhesive may be in sheet form and applied to the fabric material prior to electrodeposition. In general, the adhesive sheet will allow a plurality of openings of the desired shape and size to be formed prior to drilling and applying to the fabric material. Preferably, this perforation will be by cutting the opening from the sheet in any convenient way.

The adhesive sheet is then heated in contact with the fabric material and pressure is applied to allow the adhesive to be absorbed into the space within the fabric material. Once fully penetrated, the fabric material is cooled.

The fabric material is then electrodeposited with metals and abrasives as described above.

The resulting abrasive layer has an adhesive on both sides of the fabric material and the metal periphery, and can be easily adhered to the backing material by attaching the backing material to the back and heating the adhesive to adhere the fabric material to the backing material. The adhesive is preferably a hot-melt adhesive, which is acid resistant and waterproof.

Other techniques for producing abrasive fabrics include the use of electrically conductive fabrics, coating the fibers with metal or electrodepositing the metal using metal fibers to result in a pattern.

In principle, any metal that can be electrodeposited can be used, but the metal used substantially is usually nickel. Various abrasive particles can be included in the metal. Typically, the abrasive particles are diamond or synthetic boron nitride.

An abrasive layer (hereinafter referred to as "polishing fabric") consisting of a mesh containing a metal deposit containing an abrasive is generally adhered to a backing member such as a backing sheet or a solid substrate, for example, of woven material. The adhesive present in the abrasive fabric may be used to adhere to the backing member, and / or the adhesive may be applied to the backing and / or abrasive mesh by coating, spraying, dipping, lamination, or the like.

In one known method, an abrasive fabric is bonded to a polyester-cotton fabric backing using a hot-melt polyester adhesive under heat and pressure. The adhesive may be applied in the form of a separate film sold commercially on release paper, or may be present on the surface of the polyester-cotton fabric.

Heat and pressure in the bonding process cause the hot-melt adhesive to flow and penetrate the abrasive fabric. This bonding technique has been used in abrasive products in the form of discs, blocks, piles and pads. The other surface of this polyester-cotton fabric backing may form a surface for attachment such that it is adhered to the block, pad or to which the abrasive product and the appropriate support are attached.

According to a second known technique, a two-component crosslinkable polyurethane adhesive solution is prepared and the abrasive fabric is completely immersed in this solution and then taken out again and left to dry. Typically, this operation is repeated one or more times to ensure that the adhesive has a satisfactory thickness.

One side of the flexible fabric backing substrate is coated with the same adhesive solution and left to dry. Generally, one or more additional coatings are performed.

The back side of the abrasive fabric and the adhesive coated side of the fabric are placed in contact and bonded by applying heat and pressure.

Products comprising abrasive mesh adhered to the backing have been marketed since the mid-1980s under the trademark DIAPAD and 3M. Abrasives are available in the form of belts, disks, pads and blocks, and have been used to polish various hard materials, including metals, glass and stones such as granite and marble. In some harsh use conditions, especially at high temperatures, the metal deposits may peel off from the backing, and in extreme cases, the fabric may tear and the metal deposits separate from the abrasive.

Various attempts have been made to increase the adhesion to the backing of metal deposits. For example, 3M 901 Silane Primer, Lociite SIP (self-directed primer), Bostick 9253 primer and Ciba Geigy DZ81 acid etch primer Primers have been used with adhesives but have been found to have little improvement in properties. Various other adhesives have been used, such as reactive polyurethanes, polyesters, rubbers, nitrile rubbers, polytenes, polychloroprene rubbers and the like, but no significant improvement in properties has been seen.

It is an object of the present invention to provide an abrasive comprising an abrasive mesh having improved peel properties.

According to one embodiment of the invention,

An abrasive fabric comprising a fabric in which there is a discontinuous area of metal deposited on or through the fabric, wherein the abrasive is embedded in the metal,

Adhesive layer and

Backing equipment

Wherein the abrasive fabric is adhered to the backing substrate by an adhesive layer,

i) the surface of the abrasive fabric adhered to the backing is roughened by polishing or the like, or ii) the adhesive layer comprises an epoxy-acrylate thermosetting adhesive.

According to a second embodiment of the invention,

Providing an abrasive fabric comprising a fabric in which there is a discontinuous area of metal deposited on or through the fabric, wherein the abrasive is embedded in the metal, and

Adhering the abrasive fabric to the backing substrate with an adhesive layer

It is to provide a method for producing an abrasive article, characterized in that to roughen the surface of the abrasive fabric through polishing or the like before contact with the adhesive layer.

According to another embodiment of the present invention,

Providing an abrasive fabric comprising a fabric in which there is a discontinuous area of metal deposited on or through the fabric, wherein the abrasive is embedded in the metal, and

Adhering the abrasive fabric to the backing substrate with an adhesive layer

And an adhesive layer comprises an epoxy-acrylate thermosetting adhesive.

The products of the present invention have improved peel resistance of metal deposits, resulting in longer lifetimes and improved cutting speeds in abrasive articles.

1 is a cross-sectional view of an abrasive article of the present invention.

It was believed that the smooth surface of the metal deposits formed when the metal was electrodeposited on the electrically conductive surface did not provide the best surface for adhesive adhesion. However, I did not think it would be easy to roughen the surface. Electrodeposition of metals to roughened electrically conductive surfaces mechanically bonds metal deposits to prevent removal. Depending on the fabric material, the abrasive fabric is extremely flexible and easily torn, reducing the likelihood of roughening the surface of the metal deposit by mechanical means. Modification of the surface properties using primers, including primers that etch the surface, did not provide a noticeable improvement. It has been found that such abrasive fabrics can be grit blasted under conditions that roughen the metal deposit surface without much damage to the fabric mesh material. This method is surprising because the grit blasting conditions needed to polish the metal surface were thought to cause destruction of the fabric mesh material.

Grit blasting can be performed on any suitable machine, for example, a GUSSON® Model 300 / 20AD blast cleaner. The abrasive fabric can be easily supported by placing it on a bed of a grit-blasting machine. Alternatively, it may be fixed in any suitable position in the path of the grit particles, for example horizontally or vertically. Suitable grit include 36 to 80 grit aluminum oxide (Henry-in-Arden, UK, Abrasive Developments Ltd., Alumina Size 46, etc.) or cooled iron grit do. Generally grit blasting is carried out for up to 10 seconds per square inch, preferably for 2 to 5 seconds per square inch.

The treated abrasive mesh is soaked in a solvent such as isopropyl alcohol to remove any dirt and then adhered to the backing using conventional techniques.

Grit blasting significantly increases the surface roughness. Comparing the surface before and after grit blasting by placing a sample on a glass plate and measuring an area of 0.25 mm × 0.25 mm using a UBM topography device, the Rz (mean of the five deepest scratches) is from 2.1 μm to 6.6 μm. Increase from 0.4 to 1.5 μm in Ra (average surface treatment). In addition to polishing, any method of providing a rough surface treatment can be used.

Other polishing techniques may be used to polish the surface of the metal deposit, such as an abrasive belt or mechanical polishing using a nonwoven abrasive web in the form of a wheel, sheet or belt or the like. Suitable nonwoven abrasives are commercially available from Minnesota Mining and Manufacturing Company (St. Paul, Minn.) Under the name of SCOTCHBRITE®. The polishing process preferably increases Ra up to 0.7 μm, preferably up to 1.0 μm, more preferably up to about 1.5 μm. The polishing process preferably increases Rz to 3 μm or more, preferably to 4 μm or more, more preferably to 5 μm or more.

It has also been found that one particular type of adhesive provides significantly improved peel resistance. The use of epoxy-acrylate resins of the type described in US Pat. No. 5,086,088 improved the adhesion between metal deposits and backing both after grit blasting and untreated metal deposits. Such materials include from about 30% to about 80% by weight of a syrup of photopolymerizable prepolymers or monomers (including acrylic esters and polar copolymerizable monomers), epoxy resins containing no photopolymerizable groups or mixtures of epoxy resins. A thermosetting pressure sensitive adhesive comprising from about 60% by weight to about 60% by weight, about 0.5% to about 10% by weight thermally active curing agent for epoxy resins, about 0.01% to about 5% photoinitiator, and 0% to about 5% photocrosslinker. Imidazole and thermally expandable thermoplastic microspheres can be used in the adhesive formulation. This type of adhesive is available from 3M under the name 3M Epoxy Tape 9245. The abrasive article of the present invention can be produced by pressing and laminating an abrasive fabric to a backing using 3M epoxy tape 9245.

The present invention will now be described with reference to FIG. 1.

The abrasive comprises a fabric 2 in the form of a one-over-one mesh with warp filaments 4 and weft filaments 6. The fabric has discrete islands 8 of electrodeposited metal and is embedded with abrasive particles 10 on the island top surface. Elements indicated by reference numerals 2 to 10 constitute the abrasive fabric.

According to one embodiment of the invention, the bottom surface 12 of the electrodeposited island 8 is roughened by polishing such as grit blasting. An adhesive layer 14, preferably comprising an epoxy-acrylate thermosetting adhesive, adheres the abrasive fabric to the backing substrate 16.

The fabric material used to make the abrasive fabric can be selected from a variety of materials that may be insulating or electrically conductive, depending on the method of making the abrasive fabric. Suitable electrical insulating materials include woven fabrics and nonwovens of cotton, nylon, polyester, terylene and kevlar. Preferred insulating fabrics for use in the present invention include screen printing fabrics, in particular monofilament polyester one-over-one tissue screen printing fabrics. The electrically conductive material may be a woven or nonwoven fabric and may include conductive fibers such as metal or insulating fibers coated at least partially with a conductive material.

The invention will be explained in detail in the following examples.

The abrasive fabrics used in the examples below are the same as the abrasive fabrics used for abrasives Green 21, Black 18 and Red 18 available from 3M United Kingdom plc. The abrasive fabric comprises a monofilament polyester one-over-one mesh fabric having a mesh size of 55 μm and a fiber thickness of 27 μm. This fabric is a fabric having electrodeposited nickel circular islands embedded with diamond, and is commercially available under the tradename PES 55/28 (Sercol). Green (GN) indicates diamond particle size is 250 μm, black (BK) indicates diamond particle size is 125 μm and red (RD) indicates diamond particle size is 74 μm. Numeral 21 represents a large circular island pattern of about 4 mm in diameter and numeral 18 represents a small circular island pattern of about 1.5 mm.

<Example 1>

Grit blasting and bonding of polyurethane

GN21 and BK18 abrasive fabrics were grit blasted for about 5 seconds per square inch using aluminum oxide Safti Grit White 46 on a trademark GUYSON model 300 / 20AD blast cleaning machine.

To remove any dirt, the abrasive fabric was dipped in isopropyl alcohol.

The abrasive fabric was immersed in an adhesive bath containing 46 parts of Bostik 3206 adhesive, 6 parts of Bostik D1000 activator and 48 parts of Bostik M576 solvent, and hung on one end to dry. . This operation was repeated and the other end hung.

The polycotton backing material was roller coated with an adhesive composition comprising 71 parts of Bostik 3206 adhesive, 9 parts of Bostik D1000 activator and 20 parts of Bostik M576 solvent, and dried. Adhesive secondary coating was performed.

The backing was laminated to the back side of the abrasive mesh material by applying heat and pressure. The backing and abrasive mesh material was placed in a horizontal flat press and heated to 120 ° C. for 5 seconds at a pressure of about 6 lb / square inch (41.4 kPa). Immediately after, the stack was passed through a nip of two rollers 3 inches in diameter, 270 mm in length, one roller was steel and the other roller was silicon coated. The rollers were pressurized with a 2-inch (5 cm) diameter air ram at each end under a pressure of 100 lb / square inch (689 kPa).

The entire surface of the obtained material was roller coated with an adhesive, and the polycotton substrate was laminated to the material, leaving an unbonded portion on one edge of the resulting laminate. Additional samples were made using standard GN21 and BK18 materials.

In an Instron tension meter, the two non-bonded layers of the sample were each fixed and tested by pulling the stack apart. The following test parameters were used:

Load = 1.00 kN

Crosshead speed = 100.00 mm / min

Sample rate = 6.667 (pts / sec)

Sample width = 25 mm

Specimen thickness = 2.5 mm

Peel force is reported in Table 1 below.

Sample Peel force (kN) GN21 standard 0.078 GN21 grit blasted 0.092 BK18 standard 0.065 BK18 grit blasted 0.086

The results indicate that the grit blasting improves the adhesion between the metal deposit and the backing. The sample of the present invention retained the adhesive residue on the backside of the metal deposit after peeling, while the backside of the metal deposit of the reference material was clean. Some samples of the present invention were peeled off at the contact surface between the polycotton substrate and the diamond abrasive on the front of the metal deposit. In this sample, the peel force did not match the adhesion strength between the backing and the back side of the metal deposit because the adhesion did not drop. Thus, the adhesion strength between the backing and the back of the metal deposit in this sample is greater than the reported peel force.

<Example 2>

Grit blasting and bonding with hot-melt adhesives

Black 18 and Red 18 abrasive fabrics were grit blasted as in Example 1.

To remove any dirt, the abrasive mesh material was dipped in isopropyl alcohol.

A backing substrate comprising a polyester hot-melt adhesive thin film and a polyester-cotton blended woven fabric was pre-pressed for 20 seconds at an elevated temperature to allow the adhesive to penetrate the fabric.

The abrasive fabric was then hot pressed to a hot-melt adhesive for 20 to 25 seconds so that the adhesive flowed back to form an adhesive and the abrasive fabric was laminated to the prepared polyester-cotton fabric.

The entire surface of the obtained material was laminated on a polycotton substrate and tested as in Example 1.

The results are reported in Table 2.

Sample Peel force (kN) Black 18 standard 0.023 Black 18 grit blasted 0.032 Red 18 standard 0.024 Red 18 Grit Blasted 0.050

Grit blasting improves adhesion between the metal deposit and the backing. After peeling off, the sample of the present invention remained clean on the backside of the metal deposit of the reference material, while the adhesive residue remained on the backside of the metal deposit. In addition, some of the samples of the present invention fell off the side with the diamond abrasive, which would indicate that the actual adhesion was stronger and would mean that a true measurement of the effect of polishing the material could not be obtained. This is because the break point of this test is normally the point where the lamination of the polishing member to the backing portion always falls, and not the lamination failure of the polishing member to the support on the front side as here.

<Example 3>

As in Example 1, a belt (75 × 1850 mm) was prepared by adhering the abrasive mesh to the backing. The first belt was N125 micron pattern 18 based on 3M 6400J using BK18 abrasive mesh. The second belt was made using grit blasted BK18 as in Example 1. A third belt was made by bonding the BK18 abrasive mesh to the backing using 3M epoxy tape 9245. This tape was attached to the back side of the abrasive mesh using a manual roller. The release paper was then removed from the tape and the material was again attached to the backing material. This sandwich was then cured between two press plates at a lamination temperature of 140 ° C. Then, as a test piece, the belt was used on a rotating belt machine driven by an electric motor through a 200 mm diameter driving roller with a 200 mm diameter contact wheel at a machine speed of 40 m / sec using a 20 m diameter glass rod. Tested.

Each belt was subjected to a series of tests as reported in Table 3 below. In each test, the glass rod was brought into contact with the belt under a certain pressure until 20, 30 or 40 mm of glass was cut at one time. Additional cycles were repeated several times until the total cutting reported in Table 3 was reached. The time taken to achieve the indicated cutting was measured and the cutting speed was calculated. The conditions of this test were increasingly severe until the belt broke. Table 4 below shows the conditions of each test, the total cutting amount, the cutting speed and the total cutting speed of each test.

exam Condition Based on cutting speed (mm / sec) Cutting speed (mm / sec) Example 1 Cutting speed (mm / sec) epoxy Total cutting mm One 1a 5.11 4.70 6.00 220 2 2a 2.73 2.90 4.80 940 3 2a 1.76 2.28 2.20 1660 4 3a 2.00 2.31 2.30 2380 5 3a 1.65 2.02 1.85 3100 6 3b 1.30 1.59 1.48 4180 7 3b 0.91 1.13 1.33 5260 8 4a 1.11 1.35 2.60 5620 9 4a 1.17 1.22 6340 10 4b 1.04 7420 11 4c 0.72 8860

Condition 1a 6.2 bar, 1 serving 20 mm

Condition 2a 8.2 bar, 1 serving 20 mm

Condition 2a 8.2 bar, 1 serving 20 mm

Condition 3a 10.0 bar, 1 serving 20 mm

Condition 3b 10.0 bar, once 30 mm

Condition 3b 10.0 bar, once 30 mm

Condition 4a 12.0 bar, 1 serving 30 mm

Condition 4a 12.0 bar, 1 serving 30 mm

Condition 4b 12.0 bar, once 30 mm

Condition 4c 12.0 bar, 40 mm serving

standard Grit blasting Epoxy Total cutting 5620 mm 8860 mm 6250 mm Total time 3838 seconds 7769 seconds 3391 seconds Overall cutting speed 1.45 mm / s 1.14 mm / sec 1.84 mm / s Ending point Peeling Peeling Peeling

The observations of this test are as follows:

The 3M grit blasted belt showed the best total cut and the longest life, suggesting superior lamination strength. A significant improvement over the “standard” belt in both life and total cutting.

Epoxy belts exhibited the best cutting speeds, especially at pressure changes, and were clearly better than "reference" belts at the total cutting, but not better than grit blasted structures.

Claims (23)

An abrasive fabric comprising a fabric in which there is a discontinuous area of metal deposited on or through the fabric, wherein the abrasive is embedded in the metal, Adhesive layer and Backing equipment Wherein the abrasive fabric is adhered to the backing substrate by an adhesive layer, i) the surface of the abrasive fabric adhered to the backing is roughened by polishing or the like, or ii) the adhesive layer comprises an epoxy-acrylate thermosetting adhesive. The abrasive article of claim 1, wherein the metal is nickel. The abrasive article of claim 1 or 2, wherein the abrasive is diamond or cubic boron nitride. The abrasive article of claim 1, wherein the adhesive layer comprises a polyurethane adhesive. 4. The abrasive article of claim 1, wherein the adhesive layer is a hot-melt adhesive. The abrasive article of claim 5, wherein the adhesive layer is polyester. The adhesive layer according to any one of claims 1 to 3, wherein the adhesive layer is (a) about 30% to about 80% by weight of a photopolymerizable monomer or prepolymer syrup containing acrylic esters of non-tertiary alcohols and moderately polarizable copolymerizable monomers, (b) about 20% to about 60% by weight of an epoxy resin or mixture of epoxy resins that does not contain photopolymerizable groups, (c) about 0.50 wt% to about 10 wt% of a heat-activated curing agent for an epoxy resin, (d) about 0.01% to about 5% photoinitiator and (f) 0% to about 5% photocrosslinker An abrasive article comprising a thermosetting pressure sensitive adhesive which is a photopolymerization reaction product of a blend composed mainly of a. The abrasive article of claim 1, wherein the surface roughening is achieved by polishing. 9. The abrasive article of claim 1, wherein surface roughening is achieved by grit blasting. 10. The abrasive article of claim 1, wherein the abrasive article is in the form of a belt. 10. The abrasive article of claim 1, wherein the abrasive article is in the form of a pad, disk, block, strip, or roll. Providing an abrasive fabric comprising a fabric in which there is a discontinuous area of metal deposited on or through the fabric, wherein the abrasive is embedded in the metal, and Adhering the abrasive fabric to the backing substrate with an adhesive layer And roughening the surface of the abrasive fabric before contacting the adhesive layer. The method of claim 12, wherein the surface of the abrasive fabric is roughened by polishing. The method of claim 13, wherein the surface is polished by grit blasting. 15. The method of claim 14, wherein grit blasting is done using 36 to 80 grit sizes. The method of claim 13 or 14, wherein the grit particles are selected from aluminum oxide and cooled iron grit. 17. The method of any of claims 12-16, wherein the adhesive layer comprises a polyurethane adhesive. 17. The method of any of claims 12-16, wherein the adhesive layer is a hot-melt adhesive. 19. The method of claim 18, wherein the adhesive layer is polyester. The method according to claim 12, wherein the adhesive layer is (a) about 30% to about 80% by weight of a photopolymerizable monomer or prepolymer syrup containing an acrylic acid ester of a non-tertiary alcohol and a moderate polar copolymerizable monomer, (b) about 20% to about 60% by weight of an epoxy resin or mixture of epoxy resins that does not contain photopolymerizable groups, (c) about 0.50 wt% to about 10 wt% of a heat-activated curing agent for an epoxy resin, (d) about 0.01% to about 5% photoinitiator and (f) 0% to about 5% photocrosslinker A thermosetting pressure-sensitive adhesive which is a photopolymerization reaction product of a blend composed mainly of a. Providing an abrasive fabric comprising a fabric in which there is a discontinuous area of metal deposited on or through the fabric, wherein the abrasive is embedded in the metal, and Adhering the abrasive fabric to the backing substrate with an adhesive layer And the adhesive layer comprises an epoxy-acrylate thermosetting adhesive. The method of claim 21 wherein the adhesive layer is (a) about 30% to about 80% by weight of a photopolymerizable monomer or prepolymer syrup containing acrylic esters of non-tertiary alcohols and moderately polarizable copolymerizable monomers, (b) about 20% to about 60% by weight of an epoxy resin or mixture of epoxy resins that does not contain photopolymerizable groups, (c) about 0.50 wt% to about 10 wt% of a heat-activated curing agent for an epoxy resin, (d) about 0.01% to about 5% photoinitiator and (f) about 0.01% to about 5% of the photocrosslinker A thermosetting pressure-sensitive adhesive which is a photopolymerization reaction product of a blend composed mainly of a. An abrasive fabric comprising a fabric in which there is a discontinuous area of metal deposited on or through the fabric, wherein the abrasive is embedded in the metal, Adhesive layer and Backing equipment Wherein the abrasive fabric is adhered to the backing substrate by an adhesive layer, the adhesive layer comprising an epoxy-acrylate thermosetting adhesive.