Improved method for manufacturing a laminated product

Abstract

Improved method for manufacturing a laminated product The invention relates mainly to a method for manufacturing a laminated product having an adjustable thickness by thinning, comprising steps in which: - a liquid solution of unpolymerized resin is prepared in a solvent; - several sheets are coated with said liquid solution so as to form a resin film on at least one face of the sheet; - the sheets are stacked so as to separate them from each other by said resin film; and - the resin is brought to a state of polymerization which gives the shim a bonding strength between sheets which is weaker than the resistance of the sheets to tearing, resulting in each sheet being able to be detached from the stack without tearing, characterized in that the solvent is water-based, preferably the liquid solution is an aqueous phase epoxy resin solution.

Description

Title of the invention: Improved method of manufacturing a rolled product Technical field

[0001] The invention falls within the field of laminated products and more particularly in the field of peelable shims.

[0002] PRIOR ART AND DISADVANTAGES OF PRIOR ART

[0003] More specifically, the invention relates to a method for manufacturing a laminated product having an adjustable thickness by disintegration, this product comprising an alternating stack of sheets and layers of an adhesive material, each sheet having an intrinsic tear resistance, and each layer of adhesive material connecting two adjacent sheets of the stack to each other by a bonding force lower than the tear resistance of the sheets, with the result that each sheet can be detached from the stack without tearing.

[0004] Products of this type are known from the prior art, and are used in particular as adjustment shims for mechanical assemblies. These assemblies generally have significant clearances at certain points, resulting from the combination of manufacturing tolerances. These clearances are compensated by inserting shims. The thickness of these shims is adjusted by removing the upper or lower sheets one by one, until the desired thickness is reached.

[0005] The sheets are generally metal sheets, for example based on aluminum, stainless steel, carbon steel, brass or titanium, or sheets of thermoplastic organic polymer.

[0006] In a known manner, a liquid solution of unpolymerized resin in a solvent is prepared, several sheets are coated with said liquid solution so as to form a resin film on at least one sheet face and the sheets are stacked so as to separate them from each other by said resin film. The resin is then brought to a state of polymerization which gives the shim a bonding force between sheets which is weaker than the tear resistance of the sheets, with the result that each sheet can be detached from the stack without tearing. The polymerization can be carried out by heating in a press at a temperature and for a time determined according to the desired properties of the laminated product, in particular in terms of peelability. The laminated product is finally machined or cut.

[0007] Also in a known manner, the adhesive material is a polymerizable material based on monomers or oligomers of the epoxy, phenolic, vinyl ester, vinyl, acrylic or other type, which allow the production of a thermoplastic or a thermo curable by crosslinking. A thermosetting material is preferably chosen for its hardness characteristics during temperature increases, particularly an epoxy resin.

[0008] These resins are mixed with powerful and polluting solvents. Acetone is an example.

[0009] Consequently, operators on production lines are in permanent contact, particularly through inhalation, with these solvents, which puts them at risk of skin irritation and desensitization.

[0010] Furthermore, the contact of operators with these solvents is not limited to the manufacturing process of rolled products but also to the cleaning of tools such as the gluing machine, the press and the cutting machine. These tools are in fact impregnated with resin and their cleaning requires the use of solvents, for example acetone.

[0011] To limit the undesirable effects of these solvents, exhaust ventilation systems are installed to evacuate them in a gaseous state. However, these systems create swirling air flows laden with dust which can degrade the quality of the final rolled product by the appearance of spikes on the surfaces. This can lead to a reject level of up to 50% when the sheets used to make the rolled product are made of aluminum, a metal particularly sensitive to dust pollution.

[0012] OBJECTIVE OF THE INVENTION

[0013] The invention relates to a method for manufacturing a rolled product making it possible to overcome the aforementioned drawbacks. Statement of the invention

[0014] To this end, the method of manufacturing a rolled product having an adjustable thickness by disintegration of the invention comprises steps in which:

[0015] - a liquid solution of unpolymerized resin in a solvent is prepared;

[0016] - several sheets are coated with said liquid solution so as to form a film of resin on at least one side of the sheet;

[0017] - the sheets are stacked so as to separate them from each other by said film of resin; and

[0018] - the resin is brought to a state of polymerization which gives the wedge a strength of bond between sheets which is weaker than the tear strength of the sheets, resulting in each sheet being able to be detached from the stack without tearing,

[0019] The method being characterized in that the solvent is water-based.

[0020] Advantageously, the liquid solution is an epoxy resin solution in aqueous phase. DETAILED DESCRIPTION OF THE INVENTION

[0021] Other features and advantages of the invention will become clear from the des- description given below.

[0022] The present invention relates to a laminated product having an adjustable thickness by disintegration, this product comprising an alternating stack of sheets and layers of an adhesive material, each sheet having an intrinsic resistance to tearing, and each layer of adhesive material connecting two adjacent sheets of the stack to each other by a bonding force lower than the resistance of the sheets to tearing, as a result of which each sheet can be detached from the stack without tearing.

[0023] In a known manner, the laminated product of the invention forming a peelable adjustment shim is manufactured in the following manner.

[0024] Sheets are prepared which are generally metal sheets, for example based on aluminum, stainless steel, carbon steel, brass or titanium, or sheets of thermoplastic organic polymer. The sheets are cut to the desired dimensions.

[0025] The sheets are bonded on one side with a thermosetting polymer. The thermosetting polymer is a water-based epoxy resin, for example marketed under the trade name Sikafloor®-2540 W.

[0026] The gluing operation is carried out by any type of gluing machine, spraying by means of a nozzle or a gun, by application with a manual roller, by printing on an offset type machine, or by dipping the sheet in a bath of adhesive material.

[0027] The aqueous phase epoxy resin constitutes, after its treatment of crosslinking the monomer into polymer, an adhesive material, its quantity and its treatment being chosen and adapted in such a way that the bonding force binding two adjacent sheets is weaker than the resistance of these sheets to tearing, which results in each sheet being able to be detached from the stack without tearing.

[0028] Adjuvants are added, in some cases, to the resin. These adjuvants may include hardeners to give the laminated product characteristics.

[0029] The glued sheets finally undergo a final polymerization operation under pressure. This operation consists of placing the sheets in a stack, between two parallel flat supports, these supports being pressed against each other at room temperature or hot in a heating press for a predetermined time so that the resin polymerizes.

[0030] This operation must give the rolled product the desired mechanical qualities of parallelism, flatness, cohesion and peelability.

[0031] The flat supports consist of two calibrated steel plates of great thickness, for example 50 mm. The plates are crossed at the periphery by threaded rods or screws, on which a tightening is applied.

[0032] The polymerization is carried out with temperature cycles between 150 and 200°C, preferably around 200°C for a duration between 5 and 12 hours depending on the desired peelability.

[0033] Finally, the rolled product is machined or cut if necessary to the appropriate dimensions, so that it has, in the plane of the sheets, the correct shapes and dimensions.

[0034] The use of aqueous epoxy resin helps to safeguard the health of operators. In addition, the tools can be cleaned very quickly with water. Furthermore, the various containers used during the manufacturing process can be reused after simple cleaning with water. Finally, it is no longer necessary to use suction ventilation systems, which reduces the scrap rate.

[0035] The manufacturing process is thus secure, simplified, and the associated costs reduced. In addition, the process of the invention respects both the environment and the health of operators. Examples

[0036] The aqueous epoxy resin used is marketed, in particular, under the trade name Sikafloor®-2540 W.

[0037] The method of manufacturing the laminated product involving the use of this aqueous epoxy resin is as previously described.

[0038] Peelability tests are performed according to ASTM D 903.

[0039] The results are presented in the Table below. Peelability ++ - Insufficient

[0040] + Correct

[0041] ++ Very good

[0042] Table 1

Claims

Claims

1. A method of manufacturing a laminated product having an adjustable thickness by disintegration, comprising steps in which: - a liquid solution of unpolymerized resin is prepared in a solvent; - several sheets are coated with said liquid solution so as to form a resin film on at least one sheet face; - the sheets are stacked so as to separate them from each other by said resin film; and - the resin is brought to a state of polymerization which gives the shim a bonding force between sheets which is weaker than the tear resistance of the sheets, as a result of which each sheet can be detached from the stack without tearing, characterized in that the solvent is water-based.

2. Manufacturing method according to claim 1, characterized in that the liquid solution is an epoxy resin solution in aqueous phase.