ANTISTATIC FLEXIBLE ABRASIVE WITH A COMBINED SUPPORT

Abstract

A flexible antistatic abrasive with a combined support consisting of a plastic film, on which binder resins are applied, consisting of a maker coat, on which the abrasive adheres, fixed by a size coat and if necessary coated with a third binder, in which the plastic support film is laminated with at least one reinforcement substratum or base support and in which all the components of the combined support are treated with materials designed to provide the support with antistatic properties. Other aspects are disclosed and claimed.

Claims

1. A method for manufacturing a flexible and antistatic abrasive in tape form, comprising: providing an antistatic plastic film support in tape form wound on a first reel, wherein said antistatic plastic film support is coated with both: a first binder resin layer or maker coat; and abrasive granules fixed on said first binder resin layer by a second binder resin layer or size coat, whereby both the first layer of resin or maker coat and the second layer of resin or size coat contain carbon black, graphite, metal salts or other antistatic agents, whereby said antistatic plastic film support; providing an adhesive or glue containing carbon black, graphite, metal salts or similar antistatic agents; providing a base support in tape form and wound on a second reel, said base support being comprised of a material selected from the group consisting of paper or fabric containing carbon black, graphite, metal salts or other antistatic agents; unwinding the plastic film support from said first reel and transferring it to a first lamination cylinder; unwinding the base support from said second reel and transferring it to a second lamination cylinder that is in contact with said first lamination cylinder; pouring said adhesive or glue in the contact area of said first and second lamination cylinders during rotation of said first and second lamination cylinders; whereby a laminated film in tape form is formed, said laminated film being constituted by a plastic film comprising an abrasive and a base support made of paper or fabric; and transferring said laminated film to a drying oven, whereby the transferred laminated film is wound a third reel.

2. The method of claim 1, wherein said plastic film support is coated with a third layer or supersize coat of resin containing carbon black, graphite, metal salts or other antistatic agents an antistatic surface.

3. The method of claim 1, wherein said plastic film support is a polyester film comprising antistatic properties.

4. The method of claim 1, said adhesive or glue comprises vinyl or polyurethane.

5. A method for manufacturing a flexible and antistatic abrasive in tape form, comprising: providing a plastic film support in tape form and wound on a first reel; providing an adhesive or glue containing carbon black, graphite, metal salts or similar antistatic agents; providing a base support in tape form and wound on a second reel, said base support being either made of paper or fabric containing carbon black, graphite, metal salts or similar antistatic agents; unwinding the plastic film support from said first reel and transferring it to a first lamination cylinder; unwinding the base support from said second reel and transferring it to a second lamination cylinder that is in contact with said first lamination cylinder; pouring said adhesive or glue in the contact area of said first and second lamination cylinders during rotation of said cylinders; whereby a laminated film in tape form is formed, said laminated film being constituted by a plastic film comprising an abrasive and a base support made of paper or fabric; wherein said laminated film in tape form is further moved to a first working station in which a first binder or maker coat is deposited on the plastic side of said laminated film; wherein said laminated film in tape form is further moved to a second working station in which abrasive in grains is deposited on said first binder while said first binder is still wet; wherein said laminated film in tape form is further moved to a first oven where said first binder is dried and cured, thereby blocking said grains; wherein said laminated film in tape form is further moved to a third working station in which a second binder or size coat is deposited on the film; wherein said laminated film in tape form is further moved to a second oven where said second binder is dried and cured, thereby covering the abrasive grains; and whereby said laminated film in tape form is further moved to a third reel, upon which it is wound.

6. The method of claim 5, wherein said first and second binders are selected from the group consisting of animal glue, ureic glue, phenolic glue, and epoxy glue.

7. The method of claim 5, wherein the working temperature of said first and second ovens comprises a range between 40 C. and 130 C.

8. The method of claim 5, wherein said abrasive grains are composed of a substance selected from a group consisting of at least one of aluminum oxide, silicon carbide, zirconium, ceramic, diamond, titanium carbide, and titanium oxides.

9. The method of claim 5, wherein said first and second binders are deposited on the plastic side of said laminated film.

10. A method for manufacturing a flexible and antistatic abrasive in tape form, comprising: providing a plastic film support in tape form and wound on a first reel; providing an adhesive or glue containing carbon black, graphite, metal salts or similar antistatic agents; providing a base support in tape form and wound on a second reel, said base support being either made of paper or fabric containing carbon black, graphite, metal salts or similar antistatic agents; unwinding said plastic film support from said first reel and transferring it to a first working station in which a first binder or maker coat is deposited on a side of said plastic film; wherein said plastic film in tape form is further moved to a second working station in which abrasive in grains is deposited on said first binder while said first binder is still wet; wherein said plastic film in tape form is further moved to a first oven where said first binder is dried and cured, thereby blocking said grains; wherein said plastic film in tape form is further moved to a third working station in which a second binder or size coat is deposited on the film; wherein said plastic film in tape form is further moved to a second oven where said second binder is dried and cured, thereby covering the abrasive grains; whereby said plastic film in tape form is further moved to a first lamination cylinder; unwinding the base support from said second reel and transferring it to a second lamination cylinder that is in contact with said first lamination cylinder, pouring said adhesive or glue in the contact area of said first and second lamination cylinders during rotation of said cylinders, and whereby a laminated film in tape form is formed, said laminated film being constituted by a plastic film comprising an abrasive and a base support made of paper or fabric.

11. The method of claim 10, wherein said first and second binders are composed of a substance selected from the group consisting of animal glue, ureic glue, phenolic glue, and epoxy glue.

12. The method of claim 10, wherein the working temperature of said first and second ovens ranges bet comprises a range between 40 C. and 130 C.

13. The method of claim 10, wherein said abrasive grains are composed of a substance selected from a group consisting of at least one of aluminum oxide, silicon carbide, zirconium, ceramic, diamond, titanium carbide, and titanium oxides.

14. The method of claim 10, wherein said first and second binders are deposited on the plastic side of said laminated film.

Description

DESCRIPTION OF THE DRAWINGS

[0051] Other features and advantages of the invention will become clear on reading the description given below of one embodiment, provided as a non-binding example, with the help of the accompanying drawings, in which:

[0052] FIG. 1 represents a schematic diagram of the production of the flexible abrasive on a combined support by means of lamination;

[0053] FIG. 2 represents a cross-section of the flexible abrasive on a combined plastic film support and base support.

[0054] FIG. 3 represents a schematic diagram of the production of the flexible abrasive on a combined support according to the conventional method, that is to say starting from a laminated support;

[0055] FIG. 4 represents a schematic diagram of the production of the flexible abrasive on a combined support by means of lamination in line after preparation of abrasive according to the conventional method.

DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION

[0056] Reference is initially made to FIG. 2 which shows a cross-section of the flexible abrasive on a combined plastic film support and base support.

[0057] According to the invention, the flexible abrasive on a combined support indicated overall with the reference number 10 comprises the combination, obtained in various ways, of a flexible abrasive on plastic film 11, comprising binding resins 8, with a base support or substratum 12 in Velcro and/or paper and/or fabric and/or sponge or other similar materials.

[0058] More specifically, the combined plastic film/substratum indicated with reference number 9 consists of the layered combination of the following materials: a layer of plastic film 13, a base support or substratum 12 in Velcro/paper/fabric/sponge/(other similar materials), and a layer of adhesive material 18, such as glue or the like.

[0059] The flexible abrasive on plastic film (11) consists of: a layer of plastic film 13, a first intermediate binder layer or Maker Coat 14, a second binder layer or Size Coat 15 which holds the layer of abrasive grains 16, and finally a third binder layer 17.

[0060] According to the invention, the flexible abrasive on plastic film 11 is combined with the base support or substratum 12 in Velcro/paper/fabric/sponge, the base or substratum 12 being fixed to the plastic film 13 by means of a layer of adhesive material 18, such as glue or the like.

[0061] The above is achieved by means of a continuous lamination process, and FIG. 1 shows an example of the creation of the flexible abrasive on a combined plastic filmsubstratum support by means of lamination.

[0062] With reference to FIG. 1, the plant that allows the aforesaid lamination process indicated overall with 19 comprises a reel 20 of flexible abrasive on plastic film 21 which is transferred to a lamination cylinder 22 positioned in contact with an additional lamination cylinder 23 which receives the sheet of support material from a reel 25. A container 26 of glue 27 is positioned between the two cylinders.

[0063] The laminated film 28 exiting from the two cylinders 22 and 23 can pass through a drying oven 29 before being wound on a reel 30.

[0064] The preparation of the flexible abrasive with a combined plastic film support and paper/fabric/Velcro/sponge base support for abrasive tapes can be carried out by applying the maker coat, abrasive and size coat to a combined support consisting of plastic film and paper/fabric/sponge/Velcro/other materials, and this application can be achieved in a direct fashion in two different ways: [0065] 1) Creation of the flexible abrasive on a combined support (plastic filmsubstratum) by on-line lamination before the preparation of the abrasive according to the traditional method (FIG. 3), and according to this method the combined support is laminated on-line and then coated with the maker coat, abrasive grains, size coat and third layer; [0066] 2) Creation of the flexible abrasive on a combined support (plastic filmsubstratum) by on-line lamination after the preparation of the abrasive according to the traditional method (FIG. 4), and according to this method the substratum is laminated on-line after the plastic film has been coated with the maker coat, abrasive grains, size coat and third layer.

[0067] FIG. 3 shows a plant suitable for the creation of the flexible abrasive on a combined support (plastic filmsubstratum) by on-line lamination before the preparation of the abrasive according to the traditional method.

[0068] This system optimizes production costs thanks to the continuous lamination and production of the abrasive process on the plastic film side.

[0069] The working cycle of the lamination unit 31 shown in FIG. 3 comprises the presence of a reel of plastic film 32 and a reel of support base material 33 of paper, fabric, Velcro or sponge. These materials are laminated with the glue by means of the lamination cylinders 34 and and the combined plastic filmbase material (substratum of paper, Velcro, fabric or sponge) support moves on to the abrasive process stage. The parts of the plant necessary for this process are listed below: [0070] The film passes through the printing area 36, where the combined support is printed on the support side with the distinctive features of the product being processed. [0071] The film passes through the first binderMaker coat 37, where a binder, which can be an animal glue, a ureic glue, a phenolic glue, an epoxy glue or any type of resin or glue that can be used to create adhesion of the abrasive to the plastic support, is deposited on the combined support. [0072] The sector 38 ensures that the abrasive is deposited on the combined support on which the first binder is still wet. The first binder must not be completely dry or catalysed in order to allow the adhesion of the grains. The abrasive is intended in a broad sense since it can be aluminium oxide, silicon carbide, zirconium, ceramic, diamond, titanium carbides or oxides or a mixture of any of the former including any other type of material that can be used as an abrasive. [0073] The film passes through a first oven 39 which dries and cures the first binder, allowing the abrasive grains to grip the combined support. The required temperature depends on the type of binder used and can vary from 40 C. to 130 C. The time needed in the oven varies according to the type of grain and resin used, varying from a minimum of 1 minute to a maximum of 2 hours. [0074] The film now passes through the second binderSize coat 40, where, once the first resin is dry, the product (consisting of the combined support, the first binder and the abrasive grains) is coated with a fixing binder or size coat, which in turn can be an animal glue, a ureic glue, or a phenolic glue, etc., depending on what the product will be used for. This binder is deposited on the product by means of rubber rollers, by air, spray or other systems. This resin coating can contain fillers such as calcium or potassium carbonate, iron oxides, dyes, stearates, and any other substance that can have a technical value for the use of the product or the economic property of the product. [0075] Once the second binder has been applied, the product enters the second oven 41 for curing. The required temperature depends on the type of binder used and can vary from 40 C. to 130 C. The time needed in the oven varies according to the type of grain and resin used, varying from a minimum of 1 minute to a maximum of 2 hours. [0076] At the end of the process the product is wound on the finished reel 42 and, depending on the binders used, can be used as it is or transferred to post-curing ovens for perfect catalyzing of the binders before the product is used.

[0077] FIG. 4 shows a plant suitable for the creation of the flexible abrasive on a combined support (plastic filmsubstratum) by on-line lamination after the preparation of the abrasive on plastic film according to the traditional method.

[0078] This system optimizes production costs thanks to the continuous lamination and production of the abrasive process on the plastic film side.

[0079] The cycle begins from a reel of plastic film 43 positioned on an unwinder at the start of the plant, from which the film passes through a printer 44 for printing on the support side with the distinctive features of the product being processed.

[0080] The film passes through the first binderMaker coat 45. A binder, which can be an animal glue, a ureic glue, a phenolic glue, an epoxy glue or any type of resin or glue that can be used to create adhesion of the abrasive to the plastic support, is deposited on the combined support.

[0081] The film now passes through the sector 46 where the abrasive is deposited while the first binder is still wet. The first binder must not be completely dry or catalysed in order to allow the adhesion of the grains. In this case too, the abrasive is intended in a broad sense since it can be aluminium oxide, silicon carbide, zirconium, ceramic, diamond, titanium carbides or oxides or a mixture of any of the former including any other type of material that can be used as an abrasive.

[0082] The film passes through a first oven 47 which dries and cures the first binder, allowing the abrasive grains to grip the plastic film by means of the second binderSize coat 48, and through the second oven 49 for curing.

[0083] At this point, that is to say once the flexible abrasive on the plastic film is ready, lamination of the abrasive to the substratum (paper, fabric, Velcro or sponge) takes place.

[0084] Similar to the previous cases, these materials are laminated in the lamination unit 50 by means of lamination cylinders using glue. The combined plastic filmbase support (substratum of paper, Velcro, fabric or sponge) support is wound on a reel 51 and, if necessary, passed through a drying oven 52.

[0085] According to the invention, the main components of the combined plastic film/paper abrasive (that is to say the abrasive film and the paper/support) have antistatic properties.

[0086] In addition, to allow the combination of the main components to also be antistatic, the glue used for the lamination also has antistatic properties. Therefore, according to the invention, carbon black, graphite, metal salts or similar are added to the binding resins (make coat and size coat) for plastic film abrasives.

[0087] This ensures an abrasive film with antistatic properties.

[0088] As far as the second support is concerned (whether it is paper, fabric, or sponge, etc.) the procedure is as follows:

a) Paper type support: carbon black, graphite, metal salts or similar are added to the paper pulp when the paper is produced, thus guaranteeing that the paper is antistatic.
b) Fabric type support: compounds able to form a reticulated polymeric structure around the filaments are used for fabric supports.
c) Sponge type supports: ion exchanger resins/sponges are used in this case.

[0089] In addition, to ensure that the combination of abrasive film and second support is also antistatic, an adhesive or glue with antistatic properties is use in the lamination step according to the invention. In particular, carbon black, graphite, metal salts or similar are added to the glue (whether it is vinyl, polyurethane or another type) to allow movement of the electric charges.

[0090] The abrasive tape according to the invention is thus completely antistatic, achieving the predefined aims.

Application Examples

[0091] The following non-binding examples further describe the invention. All the measurements described in the following examples respect the international system.

TABLE-US-00001 TABLE 1 TYPE OF MATERIALS used in the test Name Detailed Description Paper Paper Support weight A (80 g/m2) supplied by Arjo Wiggins or Kimberly Clark or other suppliers. Fabric Fabric Support type X supplied by Eratex Germany Velcro Nylon-Polyester Velcro (90 g/m2) supplied by IVM srl Italy Adhesive Bicomponent adhesive supplied by Concorde Adesivi Italy Abrasive Abrasive on film support type GF02 supplied Film by Naploen Abrasives

[0092] Test Conditions and Parameters:

[0093] Type of abrasive tapes: Abrasive tape with combined support produced by laminating Abrasive Film and Paper, Abrasive Film and Velcro, Abrasive Film and Fabric

[0094] Tape dimensions and grain: 150 mm9450 mm grain, P1000, P1200 and P1500

[0095] Type of join: Head to head join

[0096] Automatic machine: Nerli.

[0097] Operating parameters: Minimum speed 1.5 m/s, Max 9 m/s. Minimum pressure 1 bar, Maximum pressure 4 bars.

[0098] Type of laminar tape: Felt

TABLE-US-00002 TABLE 2 FRICTION Test to evaluate the increase of friction due to the combined substratum-plastic film support. Type of Min. Max. Min. Max. Support: speed speed pressure pressure Stop Paper 1.5 9 1 bar 4 bars No Fabric 1.5 9 1 bar 4 bars No Velcro 1.5 9 1 bar 4 bars No Film 1.5 7.6 1 bar 1.8 bars YES

[0099] The test was carried out using a Nerli semi-automatic machine. The objective was to evaluate the working conditions to discover why the abrasive tape with different supports stopped when the speed and pressure changed. The halt of the abrasive tape shows that the friction of the abrasive filmpiece being processed is greater than the friction of the supportmovement pulleys.

[0100] The data reported in table 2 show that a tape of flexible abrasive, consisting only of abrasive plastic film, reaches lower values of speed and pressure than those of other combinations (film-paper, film-fabric, film-Velcro). The abrasive consisting of a combined support reaches the limit working conditions of the machine (minimum/maximum pressure, minimum/maximum speed) without stopping.

TABLE-US-00003 TABLE 3 FINISH Test to evaluate the improved finish due to the combined substratum-plastic film support. Type of Finish Obtained Abrasive: (Ra) Notes Paper-Film 0.51 Fabric-Film 0.58 Velcro-Film 0.50 Best finish and duration Film only 0.54 Traditional 0.65 Rapidly decays Abrasive

[0101] The piece to be sanded (same size and type of paint) and the conditions (same machine speed and pressure) being the same, the grain of the tapes being the same, the finish of the pieces sanded with the abrasive on a laminated support is better. The constancy of the roughness obtained with the products on a laminated support is also markedly superior (approx. 1.7:1).

TABLE-US-00004 TABLE 4 CLOGGING Test to evaluate the greater duration (less tendency to clog) due to the combined substratum-plastic film support with respect to a traditional abrasive and to a simple film abrasive. Type of Number of Abrasive: pieces Notes Paper-Film 7 Fabric-Film 7 Velcro-Film 7 Best finish and duration Film only 6 Traditional 4 Finish at the 4th piece Abrasive very low

[0102] The piece to be sanded (same size and type of paint) and the conditions (same machine speed and pressure) being the same, the grain of the tapes being the same, the life of the abrasive on a combined film support is much longer than that of traditional abrasives (abrasive currently used in the process).

TABLE-US-00005 TABLE 5 INSTALLATION Test to evaluate the easier handling (easier installation) due to the combined substratum-plastic film support with respect to a traditional abrasive and to a simple film abrasive. Type of Installation time Abrasive: (sec) Notes Paper-Film 45 sec Standard time Fabric-Film 45 sec Standard time Velcro-Film 50 sec Film 55 sec Traditional 45 sec Standard time Abrasive

[0103] The working conditions being the same, the tapes produced with a laminated support have similar installation times to traditional abrasives, while those produced using only unsupported plastic film require a slightly higher handling time.

[0104] The products used also have the marked antistatic features of traditional abrasives, but guarantee a markedly better finish and resistance to clogging. The antistatic property is extremely important in the wood and painting sectors, where the electrostatic charge that accumulates on the supports can generate sparks. In certain conditions, these sparks can cause the ignition of polishing dust and of suction systems.

[0105] This invention foresees that the flexible abrasive with combined support consists of a layer of abrasive-containing resins, a support plastic film layer associated with a reinforcement substratum of paper, sponge, Velcro, fabric or other similar material which satisfies the following requirements: it is economical, resistant to tensile stress, can absorb shocks, dissipates heat easily, is extremely antistatic and has sufficient friction for use in automatic and semi-automatic machines.

[0106] The product obtained allows easier and practical handling and installation in automatic and semi-automatic sanding machines.

[0107] The resulting flexible abrasive has greater mechanical resistance to tensile stress, greater heat dissipation, less tendency to clog, greater shock-absorbance, better finishing, and excellent antistatic properties compared to a product with just film or traditional abrasives (paper, fabric, combined paper-fabric, non-woven, etc.).

[0108] The invention is described above with reference to a preferred embodiment. It is nevertheless clear that the invention is susceptible to numerous variations which lie within the scope of its disclosure, in the framework of technical equivalents.