JPS6247155B2 - - Google Patents

Abstract

A flexible coated abrasive sheet material having abrasive grains adhesively bonded to at least one side of a backing comprising at least one array of non-interlaced substantially coplanar and coparallel reinforcing textile yarns, said textile yarns, together with the yarns of all other distinct arrays, if any, furnishing most of the tensile strength of said coated abrasive in at least one direction in the plane of said flexible coated abrasive sheet material, each said one or more distinct arrays being of non-interlaced, substantially coplanar and coparallel reinforcing textile yarns present in the backing and oriented in the same direction.

Description

[Detailed description of the invention]

The present invention relates to a useful abrasive product called a coated abrasive in the art, which is made by adhering abrasive grains to at least one surface of a flexible substrate. This coated abrasive is useful, for example, as an endless abrasive belt. Coated abrasives have generally been manufactured using a variety of substrates ranging from paper, fabric, and leather to plastic films and metal sheets. The vast majority of coated abrasive products, except for specialty products, are made using paper or woven substrates. Coated abrasives, which are often subjected to high stresses during use, are made from strong paper or vulcanized fiber substrates, while coated abrasives, which require strength and flexibility, are made from woven fabric substrates. . Laminates of these abrasives have also been used and described in the literature. The first difficulty encountered when using woven fabrics as a substrate for coated abrasive products (particularly as belts) is that the inherent elongation properties of woven fabrics are due to the repeated bending of the yarns, essentially due to the entangling nature of the material. The second difficulty is that the strength of the material is reduced in some cases due to the presence of knuckles at the intersections of the threads. Knuckles are small bumps that appear on the surface of a woven fabric, resulting from the bending of yarns as they intertwine with other yarns.
The presence of such knuckles is believed to cause catastrophic failure of coated abrasive products, particularly belts, when used under severe abrasive conditions. In the present invention, an array of substantially mutually planar and mutually parallel fiber threads which are not woven but are joined by other means to form the structure of the coated abrasive. By using a coated abrasive material, the desirable properties of the fabric as a base material for the coated abrasive material are inherited, and most of the unfavorable properties of the fabric are eliminated. Theoretically, ideal properties for coated abrasives would be expected if the arrays of fiber threads that make up the substrate were exactly planar and parallel to each other. Probably. However, desiring such precision in fiber arrays is neither substantial nor necessary to derive the advantages of this invention. The flexible sheet-like coated abrasive material according to the present invention is a flexible sheet-like coated abrasive material having abrasive grains bonded to at least one surface of a base material, and the base materials are each not entangled. at least two arrays of continuous reinforcing fiber threads that are substantially planar and parallel to each other; the arrays are oriented in at least two different directions in the plane of the substrate; the effective tensile strength of the coated abrasive material in each of the at least two directions of orientation is such that the effective tensile strength of the coated abrasive material in each of the at least two directions of orientation is determined by It is characterized in that the fiber threads constituting all the arrays of fiber threads are planar and parallel to each other. For the purposes of the present invention, an array is defined if all the fiber threads that make up the array can fit in two parallel planes separated by a distance of four times the average diameter of the fibers in the array. It can be said that the fibers that make up the body are substantially planar to each other. Further, if the maximum angle difference between any two fiber threads in the array is 30° or less, the array can be said to be substantially parallel to each other. By using an adhesive bonding layer of fabric or oriented fiber yarn, such as Stitchbond Marimo fabric, many of the difficulties encountered with conventional woven substrates can be avoided. That is, it is possible to avoid the problem of sudden failure and the problem of elongation caused by the presence of knuckles in the woven fabric. Furthermore, another method using a fabric made of unentangled fiber yarns as a base material of a coated abrasive material
One advantage is that such fabrics can be manufactured at higher speeds than conventional woven fabrics, increasing productivity and reducing manufacturing costs. Regarding stitchbond marimo type fabrics, this fabric is manufactured by placing the weft yarns on top of the warp yarns and sewing the warp and weft yarns together using a third fiber yarn. There is an upper limit to the number of warps per inch for such marimo-type fabrics because of the required spacing between the multiple stitching needles. Accordingly, stitchbond fabrics tend to and can be coarsened compared to conventional coated abrasive fabrics. The increased roughness combined with the use of higher tenacity multifilament yarns results in lower weight compared to conventional woven fabrics of comparable or lower strength and tear resistance, which reduces raw material costs. leading to a decrease in
Therefore, it may be required to use special techniques to fill the fiber interstices of such fabrics. However, the production of coated abrasives from stitchbond fabrics is generally similar to production from conventional fabrics. Yarn sizing, back filling or sizing, saturation, front sizing, application of maker coat, application of abrasive and final "sand" size coat are all utilized in the production of coated abrasives from Marimo-type Stitchbond fabrics. be able to. Adhesive-bonded fabrics can also be manufactured similarly to stitchbond fabrics, but instead of sewing the warp and weft threads together using a third fiber thread, a suitable adhesive is applied at some point in production. They differ in that they do so. Similarly, thermally bonded fabrics are produced by melting or softening the fiber threads themselves by applying heat to the intersection of the warp and weft threads, or by melting or softening a coating previously applied to the fiber threads. You can also do that. In some cases, it is desirable to sandwich a thin tissue sheet between the warp and weft yarns to prevent the treatment agent from penetrating too deeply into the fiber yarn arrangement during the back filling process. This can be done with a marimo machine during the manufacturing process of the base material. The coated abrasive material according to the invention is particularly suitable for the production of coated abrasive belts. In this regard, it is important to be able to control the longitudinal strength and elongation properties of the material. It is not always possible to predict the overall strength of a woven fabric in the warp direction by summing the strength of the individual warp yarns, and it is not always possible to predict the elongation properties of a woven fabric from the elongation properties of individual warp yarns. However, in the fiber yarn array used in the present invention, all of these properties can be easily controlled and predicted. Additionally, the tendency of coated abrasive belts to split due to entangled warp and weft yarns under stress during use is avoided by using an unentangled substrate in accordance with the present invention. Here, "unentangled base material" means a base material reinforced with an array of fiber yarns that are substantially mutually planar and parallel to each other without being entangled as described above. . The finishing material is not limited to a specific material, and many materials can be used as long as appropriate coverage and adhesion are achieved. The important points in finishing are to obtain good adhesion to the substrate, to properly fill the fiber thread array so that its surface is suitable for retaining the abrasive material, and to facilitate the manufacturer's coating. to prevent the final product from delaminating, cracking, or tearing.
It is also important to have adequate flexibility in the end use. Therefore, the chemical composition of the finishing composition is not important unless it significantly affects the physical properties of the untreated product. It is also possible to prepare the fiber yarn array by techniques other than using a marimo machine to prepare the unentangled substrate used in the present invention. for example,
A pre-prepared cut-to-length weft thread can be placed on the warp thread arrangement, for example at right angles, by a suitable machine or by hand. The warp threads and the placed weft threads are then joined together by step threads or adhesive. US Patent 3250655
describes this type of fabric that is bonded with an adhesive. There is also known a machine that winds an array of weft threads along the longitudinal direction of warp threads arranged in a cylindrical shape. Other machines or methods, such as weft insertion machines, can also be used to prepare fiber yarn arrays suitable for the present invention. The currently preferred material for the warp yarns is relatively high strength, low elongation polyester continuous filaments. Of course, other fiber yarns with similar or higher strength and similar or lower elongation can be used. Although less practical, lower strength and higher elongation fiber yarns may be used and still retain the other advantages of the present invention.
In addition to various organic synthetic fiber threads, glass or metal fiber threads can also be used as part or all of the fiber threads constituting the array. Preferred fiber yarns for use in the weft direction are synthetic continuous filament yarns as shown in the Examples below. Particularly useful are continuous filament yarns that have been textured to provide a false twist, or have been provided with a large bulk or surface area to provide good adhesion to finishing materials. Hereinafter, the present invention will be explained using specific examples. Example 1 This example uses a stitchbond substrate of the type described in FIG. 9 of US Pat. No. 2,890,579 in a preferred embodiment. The fabric used in this example was produced on a Marimo machine (Unitechna Ausenhandelgesellschaft mbH DDR-108 Berlin, Mohrenschutratssee 53/54 GDR). The approximately 4 inch wide weft carrier carries 61 warp yarns and provides one complete cycle for every 4 inch forward movement of the length of the web from one edge of the web. Using a 60 inch wide machine, the weft threads were interlaced with the warp threads at an angle of approximately 88° in one direction and 92° in the other direction. The stitch thread that intertwines the warp threads with the weft threads is a 70 denier polyester continuous filament. The stitch length is 1.2 mm. The warp yarns are 1000 denier Dupont type high purity polyester 68 continuous filament (breaking strength 9.2 grams/denier), and the warp density is 14 yarns per inch. The weft yarn was made from Celanese Corporation Type 731 polyester.
It is a 170 denier continuous filament (33 filaments). These yarns have a slight twist (0.25 per inch) and are bulked to provide good adhesion to subsequently applied coating agents. Strength is 3.5-3.9 grams/denier and elongation at break is 18-24%. Preferably, the thread is not treated with Corning oil. The substrate described above was then filled with the resin and acrylic latex composition to prepare it for front filling, back filling, and coating with maker grain and size coat. Next, the saturated material was dried and heat-fixed by heating. The textile finishing process will be explained in more detail below. Filling and Heat Setting The following compositions were applied at a rate of 3 to 4 pounds per sandpaper maker (330 square feet) using standard sizing rolls. The weft side of the fabric was directed upward. Full composition: Cymel 482 (American Cyanamid Company, melamine formaldehyde resin syrup, solids 80%, PH8-9) 160 parts Beetle 7238 (American Cyanamid Company, urea formaldehyde resin syrup) 124 parts water 120 parts 15% NH ₄ Cl and 24% 2-amino-2-
13 parts aqueous solution containing methylpropanol 5-7 parts of pigment dispersion can be added to the color substrate. After application of the saturating composition is completed, the fabric is dried on a tenter frame in a hot air oven for at least 3 minutes. The temperature at the inlet area of the hot stove is 205〓
and the temperature of the exit area is 350〓. A tension of at least 2 pounds per inch of width is applied while the fabric passes through the oven. This process not only dries the saturate but also heat sets the fabric. Top Fil Coating The composition of the top fill coating applied to the weft side in this example is as follows, but this composition can also be applied to the warp side if desired. (1) Phenol-formaldehyde A-stage resol resin syrup (formaldehyde/phenol ratio 1.5, solids content 78%) 199 parts (2) CaCO ₃ 160 parts (3) Sodium lauryl sulfate 2 parts (4) Hiker 2600 x 138 ( 54 parts (acrylate ester polymer latex having a glass transition temperature of 25 DEG C. manufactured by B.F. Gudryutsch Chemical Co.) The top film coating composition was applied using a box knife at a rate of 10 to 11 pounds per ream. Note that water can be added as necessary to maintain the composition at a viscosity suitable for coating. The coated fabric is again stretched on a tenter frame, applying a tension of at least 2 pounds per inch of width, and sent into a hot air oven for drying. The inlet temperature of the hot air stove is 205〓, and the outlet area temperature is 300〓. Back film coating A back film coating with the following composition is applied to the back side to which the above-mentioned front film coating is not applied. (1) Beetle 7238 Urea Formaldehyde Resin Syrup (American Cyanamid Company) 133 parts (2) Nopco NXZ Defoamer (Nopco Chemical Company, Newark, New Jersey, USA) 5.3 parts (3) UCAR151 Adhesive (Polyethylene, Polyacetic Acid) Vinyl 60% aqueous dispersion, PH4-6, Union
Carbide Corporation) 133 parts (4) Air washing clay 176 parts (5) Aqueous solution containing 15% NH ₄ Cl2 4% 2-amino-2-methylpropanol 5.3 parts (6) Viscosity at room temperature with addition of water adjusted to 11000cps (pigments can be added to the color substrate if desired). The coating composition is applied by knife coating technique at 10 pounds per ream and dried in an oven. The temperature in the inlet zone of the furnace is 150〓, and the temperature in the outlet zone is 200〓. Fabrics so coated are suitable for application of phenolic resin maker coats, abrasive grain applications, and abrasive size coat applications well known and commonly used in the art. A suitable composition for application to the front size side of the substrate is as follows. (1) Phenol formaldehyde alkali catalyst resol resin, F/P factor 2.08, PH
8.7, solid content in water 78% 7 parts (2) Phenol-formaldehyde alkali catalyst resole resin, F/P0.94, PH8.1, solid content in water 78% 3 parts (3) CaCO ₃ 1.54 x total solids 35.4 pounds/sandpaper maker ream (330 square feet) of particle size 60 high purity aluminum oxide abrasive grains are then applied by electrostatic means commonly used on adhesive coated fabrics as described above. Next, the substrate to be coated with abrasive grains was heated at 170°C for 25 minutes and at 190°C.
The abrasive grains are heated for 25 minutes at 225 mm and then for 47 minutes at 225 mm to form a dry adhesive layer (17.4 lb/S.P.M.R.) to fix the abrasive grains in the desired orientation. Thereafter, a size coat having the same composition as the manufacturer's coat except for a lower particle size is applied in a conventional manner (10.6 lb/S.P.M.R. dry). The wet adhesive layer was then heated to 125〓 for 25 minutes, 135〓 for 25 minutes, 180〓 for 18 minutes, 190〓 for 25 minutes, and then 225〓 for 25 minutes.
Dry for 15 minutes at 230 °C and then final fix for 8 hours at 230 °C. The thus coated abrasive is then prepared in conventional manner for forming belts, discs, and other desired abrasive products. In the above example, we explained the base material finishing technology that applies abrasive grain coating to the weft side of the fabric.
In other cases, it may be more preferable to coat the warp side. One of the main points of the present invention is to use arrayed yarns in which the yarns are not intertwined as seen in commonly used textiles. ” and “weft,” but these terms do not imply entanglement as described above. The sheet abrasive material prepared in the above examples can be made into a belt according to conventional techniques well known to those skilled in the art. A particularly suitable joining technique is the butt joint described in US Pat. Nos. 3,665,600 and 3,787,273. Lap splices as described in US Pat. No. 4,194,618 are also useful. In such cases, it is desirable to apply surface film coating, polishing, and manufacturer coating to the warp side rather than the weft side of the base material. In the case of a butt joint, the substrate can be coated on either side. Example 2 An adhesive-bonded abrasive-coated substrate of the present invention was placed between the top and bottom platens (manufactured by Seal) of a photo drying mounting press using two sets of substantially parallel spun polyester yarns (strength 3-5). It was prepared by crossing gram/denier, cotton count 19 single yarn). The top platen was electrically heated to 340° to 350°. A sheet of polyamide hot melt adhesive web (BOSTIC No. 5350 manufactured by USM Corporation) was sandwiched between the spun yarn layers, the press was closed, and the adhesive was melted and fixed.
The lamination time was approximately 45 seconds. The press was opened, the cross direction spun yarn beam was cut free, and the machine direction spun yarn beam was advanced to feed the next adjacent section of spun yarn onto the bottom platen of the press. The bonding process was then repeated in which the transversely spun yarn beam was passed through a press and interlaced with other beams. Approximately 8 yards of fabric was prepared in this manner. The machine direction density of the fabric prepared in this way is
The cross direction density was 47 fibers/inch and the areal density calculated from this was 6.81 ounces/ ^yard2 . The count and density of the fabric thus prepared can be easily changed by changing the count and weight of the spun yarn used for each beam. The fabric was then hot stretched by feeding it over a catenary surface at a rate of 20 feet/minute while applying a line tension of 15 pounds per inch of fabric width. During this operation the fabric was heated to 400° from the back side of the web by infrared radiation from the catenary surface.
The machine direction breaking strength was thus increased from 158 to 179 pounds per inch of fabric width, and the fabric's elongation at break was reduced from 32% to 20%. Next, using a commonly used bar coater
The following compositions were applied to the transverse sides of the hot stretched fabric with a 0.017 inch gap. (1) 133 parts of Duyuracryl 820 (acrylic latex manufactured by Greenbee S.C., solids content 45%) (2) Alkali-catalyzed bisphenol formaldehyde resin syrup (F/P factor) 4.18, solid content 73%) 87% (3) Calcium carbonate 200 parts (4) Alfonik 1012-60 (Charless S.
Nonionic surfactant (manufactured by Tanner) 7/16 parts (5) Water 25 parts Drying was performed at 200°C for 2 minutes. After drying, the machine direction side of the fabric was coated using a conventional laboratory knife-on-roll coater with the following face size composition at a rate of 20 pounds per sandpaper ream. (1) Alkaline catalyst bisphenol formaldehyde resin syrup (F/P factor = 1.48,
Solids content 73%) 195 parts (2) Alkaline catalyst phenol formaldehyde resin syrup (F/P factor = 0.94, solids content 78%) 20 parts (3) CaCO ₃ 150 parts (4) Alfonic 1012-60 (Charles S.
Nonionic surfactant manufactured by Tanner Co.) 3.6 parts (5) Water 45 parts Next, add this coating material to 250%
Dry for a minute. The fabric thus prepared was suitable for application of a phenolic resin maker coat, abrasive grain application, and abrasive size coat application according to conventional methods well known in the art. (The fabric prepared as described above will be referred to hereinafter as the base material because its manufacturer's adhesive and abrasive grains can be immediately applied). Typical examples of compositions applied to the front size side of the substrate (ie, the side to which the machine direction spun yarn is first exposed) are as follows. (1) Alkaline catalyst phenol formaldehyde resol resin (F/P factor = 2.08, PH
8.7 Solid content in water 78%) 7 parts (2) Alkaline catalyst phenol formaldehyde resol resin (F/P = 0.94, PH8.1, solid content in water 78%) 3 parts (3) CaCO ₃ 1.54 x total The solids content is then reduced to a particle size of 50 eutectic composition by conventional electrostatic means to the adhesively bonded substrates as described above.
Al ₂ O ₃ /ZrO ₂ abrasive (Norton Inc., Worcester, Mass., USA) was applied at a rate of 50 lb/sandpaper manufacturer (330 square feet). Next, the base material to be coated with abrasive grains is coated in this way.
170〓 for 25 minutes, 190〓 for 25 minutes, then 225〓 for 47
Heated for 1 minute and dried adhesive layer (17.4 lbs./S.P.
M.R.) was formed to fix the abrasive grains in a desired orientation state. Thereafter, a size coat having the same composition as the manufacturer's coat except for its lower viscosity was applied in a conventional manner. The hot adhesive layer was heated at 125〓 for 25 minutes, 135〓 for 25 minutes, 180〓 for 18 minutes, and 190〓 for 25 minutes, then 225〓.
It was dried for 15 minutes at 230°C, and then finally fixed at 230°C for 8 hours. The coated abrasive material obtained as described above is then suitably prepared into belts, discs, and other desired abrasive products in a conventional manner. A sample of the coated abrasive material prepared as described above was made into a 2-1/2" x 60" abrasive belt product. Other coated abrasive belts were prepared using the same procedure and composition as described above. however,
In preparing these comparative belts, a commonly used polyester spun yarn woven fabric was used as the fabric constituting the backing. The polyester spun yarn woven fabric used was 2 x 1 drill, warp 66/inch, weft 44/inch, yarn strength 3-5 grams/denier, warp cotton count 12, weft cotton count 15. Ta. The warp (twill) side of this fabric was used as the front side. The previously described adhesively bonded substrate of the present invention (Product A) and a product prepared using a conventional woven substrate (Product B) were compared in a series of abrasive tests. Test No. 1 Four different AISI・C1018 steels (1/2″, 2-
The narrow side of each 1/2" x 9-3/4" bar was ground alternately on the testing machine. The test machine used was 55
It had a durometer cog contact ring and was operated at a dead load of 15 pounds and a belt speed of 5000 surface feet per minute. Two belt running directions (corresponding to the warp or machine direction of the substrate) were tested for both the A and B products. It was determined that the useful life of each belt had ended when the amount of steel that could be removed during 2 minutes of continuous polishing was 5.0 g or less. Total weight of steel excluding Product A-Belt No.1 609g Product B-Belt No.2 608g Product A-Belt No.2 639g Product B-Belt No.2 619g In this test, AISI1020 hot-rollable L-beam steel ( The abrasive product was placed at a 15° angle to one of the 1/8" sides of the 1/8" x 1" x 9-3/4". Using 90 durometer flat rubber contact, belt speed is 5000 per minute
Surface foot. The force used to apply the abrasive was approximately 8.5 pounds dead liquid weight. In this application, a significant percentage of the abrasive grains and manufacturer and size adhesive coatings are shed from the substrate. The end of the useful life of the product was determined when all the abrasive grains fell off the substrate.

[Table] In the case of product B, which uses a commonly used woven fabric and a base material made of woven fabric, both belts suffered considerable damage to the weft threads, and the second belt suffered from splitting, making it impossible to test. Ta. No such damage was observed in the substrate of product A of the present invention. Although Example 2 describes one example of a coated abrasive of the present invention that utilizes a substrate without any type of binding yarn, it is understood that many modifications can be made to this embodiment within the scope of the present invention. It will be understood by those skilled in the art. For example, the transverse set of reinforcing yarns can be omitted when particularly economical requirements are high. Belts made from the product thus obtained have a low resistance to splitting, but are sufficiently usable for certain applications. Adhesives can be selected from a wide range to achieve the flexibility and damage resistance that best suits the application of the coated abrasive product. It will also be appreciated that it is possible to use more complex mechanical means that allow the abrasives described in Examples 1 or 2 to be prepared at higher speeds.

Claims (1)

[Scope of Claims] 1. A flexible sheet-like coated abrasive material having abrasive grains adhered to at least one side of a substrate, each of the substrates being substantially mutually planar with no entanglement. consisting of at least two arrays of continuous reinforcing fiber threads having a shape and parallel to each other; said arrays being oriented in at least two different directions within the plane of the substrate; The effective tensile strength of the coated abrasive material in each direction of orientation is:
The fiber threads comprising all arrays of unentangled, substantially mutually planar and mutually parallel fiber threads oriented in respective directions to withstand the substantial stresses encountered in use. A flexible sheet-like coated abrasive material characterized by: 2. The possibility of claim 1, wherein at least one of the arrays oriented in at least two different directions is composed of a fiber yarn that is bulkier than the fiber yarns of the other arrays. Flexible sheet coated abrasive material. 3. A flexible sheet-like coated abrasive material according to claim 1 or 2, in which at least one of the at least two differently oriented arrays comprises continuous filament yarns. 4. A flexible sheet-like coated abrasive material according to any one of claims 1 to 3, wherein the plurality of arrays are interconnected by stitched fiber threads. 5. A flexible sheet-like coated abrasive material according to any one of claims 1 to 3, wherein the plurality of arrays are bonded together by an adhesive. 6. A flexible sheet-like coated abrasive material according to any one of claims 1 to 5, comprising a tissue sheet. 7. A flexible sheet-like coated abrasive material according to any one of claims 1 to 6, which is in the form of an endless belt. 8. The method according to any one of claims 1 to 7, which is prepared by electrostatically applying abrasive grains onto an adhesive coating on a sheet-like substrate. Flexible sheet coated abrasive material.