Adhesive layer remover and adhesive layer removal method

Abstract

To provide a remover to peel off an adhesion layer which can peel the adhesion layer more effectively when the remover does not contact directly with the top surface and the bottom face of the adhesion layer.SOLUTION: As for a remover to remove an adhesion layer contacting with and intervening between articles and containing shellac, (1) the adhesion layer adheres to at least one surface of the article and is fixed, and (2) the remover is water solution that at least a carbonate of alkali metal is dissolved in water.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel adhesive layer remover and an adhesive layer removal method. [Background technology]

[0002] There are various methods for processing metals, glass, etc., and among these, in cutting, grinding, etc., the workpiece is temporarily fixed to a fixing base (work table) before processing. In this case, one method of temporarily fixing the workpiece to the fixing base is known to be the use of an adhesive. As such temporary fixing adhesives, in addition to synthetic resin adhesives such as epoxy adhesives, adhesives containing shellac (shellac-based adhesives) are also used.

[0003] Shellac-based adhesives are thermosetting and have the property of being able to bond to both metal and glass. Furthermore, because they are made from naturally occurring ingredients, they are also highly safe. For this reason, shellac-based adhesives have traditionally been used for bonding to fixing pedestals when processing metals, and when polishing glass or gemstones. For example, a wafer processing method has been proposed in which a wafer and a plate are temporarily attached with an alkaline aqueous solution-soluble adhesive, the wafer is processed, and then the wafer is peeled off from the plate and washed with an alkaline aqueous solution cleaning solution (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 3-203981 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional method using a cleaning solution as described above, a wafer adhered to a fixing plate is physically peeled off from the plate using a knife, scraper, etc., and then the adhesive layer remaining on the wafer surface is dissolved and removed using a cleaning solution. In other words, after physically peeling the wafer, the adhesive layer exposed on the wafer surface can only be removed by directly contacting it with a cleaning solution.

[0006] However, in actual work, it is necessary to be able to perform peeling even when the flat surfaces (top and bottom surfaces) of the adhesive layer are not in direct contact with the cleaning solution, such as when a) the workpiece is fixed to a fixing base while the peeling process is performed (i.e., the workpiece is subjected to the peeling process together with the fixing base), or when multiple physically peeled workpieces are subjected to the peeling process together (i.e., the workpieces are subjected to the peeling process with their adhesive layers facing each other).In this respect, it can be said that there is room for improvement in the conventional cleaning solutions mentioned above.

[0007] Therefore, the main object of the present invention is to provide a remover for peeling off an adhesive layer, which can more efficiently peel off the adhesive layer even when the top and bottom surfaces of the adhesive layer are not in direct contact with the remover. [Means for solving the problem]

[0008] As a result of extensive research in light of the problems of the prior art, the inventors discovered that the above-mentioned object can be achieved by employing a liquid agent containing a specific composition as an adhesive layer remover for adhesive layers containing shellac, and thus completed the present invention.

[0009] That is, the present invention relates to the following adhesive layer remover and adhesive layer removal method. 1. A remover for removing an adhesive layer containing shellac that is present between articles in contact with each other, (1) The adhesive layer is adhered and fixed to at least one surface of an article; (2) An adhesive layer remover characterized in that the remover is an aqueous solution in which at least an alkali metal carbonate is dissolved in water. 2. The adhesive layer remover according to item 1, wherein the minimum thickness of the adhesive layer is 1 mm or less. 3. The adhesive layer remover according to item 1 or 2, wherein the concentration of the alkali metal carbonate in the aqueous solution is 0.1 mol / L or more. 4. The adhesive layer remover according to any one of items 1 to 3, wherein at least the area of ​​the article that comes into contact with the adhesive layer is made of metal. 5. A method for removing an adhesive layer using the adhesive layer remover described in any one of items 1 to 4, comprising at least a step of contacting the adhesive layer with the adhesive layer remover at a temperature of 70 to 100°C. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a remover for peeling off an adhesive layer, which can more efficiently peel off an adhesive layer even when the top and bottom surfaces of the adhesive layer are not in direct contact with the remover. That is, even when the adhesive layer is in contact with and interposed between articles, and in particular when the top and bottom surfaces of the adhesive layer are isolated from the outside by the articles and cannot come into direct contact with the remover, the adhesive layer can be efficiently peeled off and removed by using the adhesive layer remover of the present invention.

[0011] In particular, adhesive layers present in gaps between articles can be removed more efficiently by treating at high temperatures using the adhesive layer remover of the present invention. This removal treatment involves bubbling with carbon dioxide gas generated from the adhesive layer remover of the present invention, and it is thought that high removal performance is achieved by combining the chemical action of the components in the adhesive layer remover of the present invention with the physical action of bubbling on the adhesive layers present between articles.

[0012] The remover of the present invention having such characteristics is effective for removing an adhesive layer remaining on a workpiece, for example, from an adhesive containing shellac used for temporary fixing. [Brief explanation of the drawings]

[0013] [Figure 1] The workpiece is shown temporarily fixed on a fixing base with an adhesive layer. [Figure 2] This shows two workpieces fixed on a fixing base via an adhesive layer. [Figure 3] 1 shows an example of the arrangement of a workpiece having an adhesive layer on its surface. [Figure 4] The figure shows an example of a series of steps in which a workpiece temporarily fixed to a fixing base is subjected to a processing process, a process of separating it from the fixing base, and a cleaning process. [Figure 5] The cleaning test method for Test Example 1 is as follows. [Figure 6] 1 is a graph showing the results of Test Example 2. [Figure 7] Test Example 3 shows the appearance of the sample after the test. [Explanation of symbols]

[0014] 10, 10a, 10b adhesive layer 10' Adhesive layer (extrusion) 11, 11a, 11b Workpiece 12 Fixing base (or article) 14 Liquid agent (adhesive layer remover) 15 Cleaning tank 21 Cutting machines DETAILED DESCRIPTION OF THE INVENTION

[0015] 1. Adhesion remover The adhesive layer remover of the present invention (the remover of the present invention) is a remover for removing an adhesive layer containing shellac present between articles in contact with each other, (1) The adhesive layer is adhered and fixed to at least one surface of an article; (2) The remover is characterized in that it is an aqueous solution in which at least an alkali metal carbonate is dissolved in water.

[0016] The remover of the present invention is composed of an aqueous solution in which at least an alkali metal carbonate is dissolved in water.

[0017] The alkali metal carbonate is not particularly limited, and at least one of lithium, sodium, potassium, rubidium, cesium, or francium carbonate can be used. Among these, at least one of (a) sodium carbonate and (b) potassium carbonate is preferably used from the standpoint of availability and ease of handling. More specifically, at least one of sodium carbonate, potassium carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate can be used. These can also be commercially available products.

[0018] The remover of the present invention is in the form of an aqueous solution in which at least an alkali metal carbonate is dissolved in water. In this case, the concentration of the carbonate in the aqueous solution is not limited, but is usually in the range of 0.05 mol / L or more, and preferably in the range of about 0.1 to 0.5 mol / L. By setting the concentration in this range, a higher removal effect can be obtained while keeping costs down.

[0019] The aqueous solution may also contain other additives as long as they do not impair the effects of the present invention. Examples include surfactants, thickeners, rust inhibitors, anticorrosive agents, pH adjusters, etc. These additives are usually preferably dissolved in water, but some of them may remain dispersed as long as they do not impair the effects of the present invention.

[0020] The adhesive layer targeted for removal in this invention is an adhesive layer sandwiched between two articles. In other words, it can peel and remove an adhesive layer sandwiched between two articles. In other words, it targets an adhesive layer in which both the top and bottom flat surfaces of the adhesive layer are shielded from the outside air by the articles. Even if the remover of the present invention is applied to an adhesive layer in this state, only the side surfaces of the adhesive layer come into contact with the remover. However, even in this contact state, the adhesive layer can be peeled and removed. As shown in Figure 1, the top surface of adhesive layer 10 is blocked by article 11, and the bottom surface of adhesive layer 10 is blocked by article or fixing base 12. Therefore, adhesive layer 10 can be efficiently peeled and removed even when the remover of the present invention cannot directly contact the top and bottom surfaces of the adhesive layer. In this case, the adhesive layer interposed between article 11 and article or fixing base 12 may be adhered and fixed only to article 11, only to article or fixing base 12, or both.

[0021] In this case, in the present invention, adhesive layers other than the adhesive layer interposed between the articles may also be removed as long as the adhesive layer interposed between the articles can be removed. For example, as shown in Figure 1, the case where adhesive layer 10 is interposed between article 11 and the area where article 11 and article or fixing base 12 face each other, and adhesive layer 10' that protrudes from between the two articles is also included in the scope of application of the remover of the present invention.

[0022] The adhesive layer may be interposed between two articles or between three or more articles. For example, as shown in Figure 2, the adhesive layer 10 interposed between the T-shaped portions of three articles 11a, 11b, and 12 can be removed.

[0023] As long as an adhesive layer is interposed between articles, it does not need to be adhered to all of the articles; it is sufficient that the adhesive layer is adhered and fixed to at least one surface of the articles. The adhesive layer being adhered to an article refers to a state in which the adhesive hardens on the surface of the article and is fixed in a layer, which is different from a state in which the adhesive layer simply abuts (contacts) another article. For example, examples include a state in which adhesive layer 10b is adhered to article 11b but only abuts article 11a without adhering to it, as shown in FIG. 3A; a state in which adhesive layer 10b is adhered to both articles 11a and 11b, as shown in FIG. 3B; and a state in which adhesive layer 10a is adhered to article 11a and adhesive layer 10b is adhered to article 11b, and adhesive layers 10a and 10b are only abutting each other without adhering to each other, as shown in FIG. 3C.

[0024] The type (use) of the article is not particularly limited, and may be either an object to be processed (workpiece) or a fixing base (work table). For example, the adhesive layer may be interposed between workpieces, or the adhesive layer may be interposed between the workpiece and the fixing base.

[0025] Furthermore, the material of the article is not limited as long as it can be bonded with a shellac-containing adhesive, and may be any of inorganic materials (metal, glass, ceramics, etc.), organic materials (plastics, rubber, wood, etc.), or composite materials of inorganic and organic materials. For example, in the present invention, an article in which at least the area in contact with the adhesive layer is made of metal can be preferably used, in terms of ease of peeling the adhesive layer. An example is an article having a metal layer and a glass layer, with an adhesive layer formed on the metal layer. Metals may be any metal that is solid at room temperature and normal pressure, and include not only metals consisting of a single element, but also alloys and intermetallic compounds containing such metals. Examples of such elements include iron, gold, copper, silver, nickel, manganese, titanium, cobalt, aluminum, tin, platinum, tungsten, molybdenum, chromium, zirconium, etc., as well as rare earth elements (cerium, samarium, neodymium, etc.). The type (use) of the article is not particularly limited and may be, for example, structural materials such as carbon steel and alloy steel, magnetic materials such as iron-based magnetic materials, electronic parts, daily necessities, etc.

[0026] The shape of the article is not particularly limited, and may be, for example, a substantially prismatic column, a substantially cylindrical column, a substantially conical column, a substantially pyramidal column, a substantially spherical column, an irregular shape, or a combination of these shapes. Therefore, for example, articles having a substantially plate-like or substantially disc-like shape may also be used.

[0027] The adhesive layer to be removed contains shellac, and is formed, for example, from an adhesive containing shellac (hereinafter also referred to as a "shellac-containing adhesive").

[0028] Shellac is known as a thermosetting natural resin obtained by purifying a resinous substance secreted by an insect called lac scale insect, and is used, for example, as an adhesive, a glossing agent, a medical masking agent, etc. In the present invention, not only natural products but also synthetic products can be used as shellac. The shellac-containing adhesive constituting the adhesive layer is not particularly limited, and known or commercially available products can be used.

[0029] The content of shellac in the adhesive may be within the range of commercially available shellac-containing adhesives, and may be, for example, within the range of about 50 to 100% in terms of solid content, but is not limited to this.

[0030] The thickness of the adhesive layer is generally sufficient as long as it is thick enough to temporarily fix the workpiece to the fixing base, and can generally be about 0.1 to 2 mm, but is not limited to this. In the present invention, effective peeling performance can be obtained even with an adhesive layer having a minimum thickness of 1 mm or less. In other words, when two objects are in face-to-face contact with each other, the adhesive layer interposed in a gap of 1 mm or less in width between the facing objects can also be peeled with the remover of the present invention. The minimum thickness refers to the thickness of the thinnest region of the adhesive layer. Furthermore, the area (flat portion) of the adhesive layer can be changed depending on, for example, the size of the workpiece, and can be, for example, 0.01 to 1 m 2 It can be, but is not limited to, the degree.

[0031] The method for using the remover of the present invention can be carried out by contacting the remover of the present invention with the adhesive layer, and more specifically, this will be explained in "2. Method for removing adhesive layer" below.

[0032] 2.Adhesive layer removal method The adhesive layer removal method of the present invention is a method for removing an adhesive layer using the adhesive layer remover of the present invention, and is characterized by including at least a step of contacting the adhesive layer with the adhesive layer remover at a temperature of 70 to 100°C.

[0033] The target adhesive layer is a shellac-containing adhesive layer interposed between articles, and the composition, arrangement, etc. of the article and the shellac-containing adhesive layer are as explained above in "1. Adhesion layer remover."

[0034] The method for contacting the adhesive layer with the remover of the present invention is not particularly limited, but a method of immersing a part or all (preferably all) of the adhesive layer in the remover of the present invention is preferably employed. For example, the method can be carried out by submerging the entire article having the adhesive layer in the remover of the present invention. This not only allows for accurate temperature control, but also allows the remover of the present invention to be continuously supplied to the contact surface, thereby enabling more reliable peeling and removal of the adhesive layer.

[0035] When immersing an adhesive layer in the remover of the present invention, it is sufficient that at least the adhesive layer to be removed is immersed in the remover of the present invention, and it is not necessary to immerse the entire article in the remover of the present invention. Also, when an adhesive layer is attached to both the article and the fixing base, the article and the fixing base can be immersed together in the remover of the present invention.

[0036] The temperature at which the adhesive layer is contacted with the remover of the present invention is usually about 70 to 100°C, with a range of 75 to 98°C being particularly preferred. Therefore, for example, it is possible to set the temperature within a range of 80 to 96°C. By setting the temperature within this range, even better adhesive layer removal effects can be achieved. The reason for this is unclear, but it is presumed to be due to the following phenomenon. The acidic components generated by dissolving shellac in water react with carbonate at high temperatures to generate relatively vigorous carbon dioxide gas. The bubbling caused by this carbon dioxide gas promotes dissolution of the adhesive layer, which is thought to facilitate peeling and removal even when the adhesive layer is interposed between articles. Therefore, this process is also preferably a process in which the remover of the present invention is contacted with the adhesive layer in a carbon dioxide gas bubbling atmosphere at a temperature of 70 to 100°C.

[0037] The time for which the remover of the present invention is brought into contact with the adhesive layer should be long enough to peel off the adhesive layer, and can be set appropriately depending on, for example, the composition of the adhesive layer to be removed, the contact temperature, the area of ​​the adhesive layer, etc.

[0038] After the adhesive layer has been completely peeled off and removed by the contact, the article can be taken out of the remover of the present invention, washed with water or the like as needed, and then dried.

[0039] <Embodiment> An embodiment of the removal method of the present invention will be described below with reference to Fig. 4. First, a workpiece 11 is fixed to a fixing base 12 via an adhesive layer 10 made of a shellac-containing adhesive (Fig. 4A).

[0040] Next, cuts are made in the fixed workpiece 11 and adhesive layer 10 using a disk-shaped cutting machine 21 (FIG. 4B). However, this step is not essential. For example, the workpiece 11 and fixing base 12 may be directly separated as shown in FIG. 4C without making cuts, or the workpiece 11 and fixing base 12 may be immersed in a cleaning tank together in the state shown in FIG. 4A.

[0041] After making the cut, the workpiece 11 is separated from the fixing base 12 by mechanical or physical force (FIG. 4C). This can be done using a known tool such as a cutter or a scraper. In this case, the adhesive layer 10 can also be heated while the separation is being performed. After the workpiece 11 and fixing base 12 are separated in this way, a portion of the adhesive layer 10 remains on each of them.

[0042] Next, the workpiece 11 with the adhesive layer 10 attached thereto is immersed in a cleaning tank 15 filled with a heated remover 14 of the present invention (FIG. 4D). Heating can be performed by heating the cleaning tank 15 from below using a heater (not shown) or the like. Since the workpieces 11 are randomly arranged, there may be cases where (i) the adhesive layer and the workpiece are alternately overlapped, (ii) the adhesive layers are overlapped with each other, (iii) the adhesive layers are aligned vertically, or (iv) they are not aligned at all. In all cases, the adhesive layer 10 can be efficiently peeled and removed. [Example]

[0043] The features of the present invention will be described in more detail below with reference to examples and comparative examples, but the scope of the present invention is not limited to these examples.

[0044] Examples 1 to 5 and Comparative Examples 1 to 9 A 200 mL solution was prepared by dissolving a predetermined amount of compound as shown in Table 1 in water.

[0045] [Table 1]

[0046] Test Example 1 A cleaning test was carried out using the liquid preparations prepared in each of the Examples and Comparative Examples. (1) Preparation of test specimens Two cold-rolled steel plates (SPCC-SD) measuring 0.8 mm × 50 mm × 70 mm were prepared, degreased, and weighed. One of the steel plates was heated to 100°C on a hot plate. A shellac adhesive was pressed against the steel plate, and approximately 0.3 g of the adhesive was applied to the entire steel plate while melting. The steel plate was then allowed to cool at room temperature to solidify the adhesive. In this way, a steel plate (test piece 1) with an adhesive layer formed on one side was prepared. The combined weight of this test piece 1 and a steel plate (test piece 2) without an adhesive layer was measured. The thickness of the adhesive layer was measured with a micrometer and found to be approximately 0.1 to 0.2 mm. (2) Cleaning test method (2-1) Method 1 200 mL of the solution was placed in a beaker and heated to 90°C. As shown in Figure 5A, test piece 2 was placed in a basket of the same size, with the adhesive layer (adhesive) of test piece 1 sandwiched between them, to prevent the two test pieces from shifting. Test pieces 1 and 2 were immersed in the solution together with the basket. After leaving the test pieces to stand for 30 minutes, they were removed, washed with water, and dried, and the combined weight of test pieces 1 and 2 was measured. (2-2) Method 2 The liquid temperature was set to 30°C, and the procedure was the same as Method 1, except that only test piece 1 was placed so that the top surface of the adhesive layer (adhesive) was in contact with the liquid, as shown in Figure 5B. (3) Calculation of removal rate In Method 1, the removal rate was calculated from the total weight of Test Pieces 1 and 2 in Methods 1 and 2, and in Method 2, the removal rate was calculated from the weight of Test Piece 1 alone based on the following formula. The results are also shown in Table 1. Removal rate (%) = {(weight of steel plate after adhesive layer formation - weight of steel plate after cleaning test) / (weight of steel plate after adhesive layer formation - weight of steel plate after degreasing)} x 100

[0047] As shown in Comparative Examples 7 to 9 in Table 1, when the adhesive layer surface is exposed to the cleaning solution, a high removal rate is obtained regardless of the type of alkali and even at low temperatures and low concentrations. In this way, when the adhesive layer is not sandwiched between gaps in the workpiece, etc., its removal performance can be demonstrated. On the other hand, as in Comparative Examples 1 to 5, when sodium hydroxide or the like is used, if the adhesive layer is sandwiched between gaps in the workpiece or the like, the removal rate drops significantly. In contrast, a high removal rate can be achieved by applying a solution containing carbonate at a constant temperature, as can be seen from the results of Examples 1 to 5. In particular, when Example 1 or Example 3 is compared with Comparative Examples 1 to 5, it is clear that the use of carbonate provides higher removal performance for shellac-containing adhesives than any other alkali. Furthermore, comparing Examples 4 and 5 with Comparative Example 6, it is clear that carbonates exhibit a high removal effect even at low concentrations. The experimental results also suggest that carbonates are less susceptible to performance degradation over long-term use. Over long-term use, the concentration of detergent components decreases for various reasons. In particular, in the case of shellac-containing adhesives, the acidic components generated when dissolved in alkali react with the alkali, causing a decrease in removal performance. Because carbonates experience little performance degradation due to concentration loss, they may be superior to other alkalis in terms of solution life.

[0048] Test Example 2 The adhesive layer removal rate was investigated using different liquid agents. The removal process was carried out in the same manner as Method 1 above, except that the liquid agent temperature was set to 60-90°C and the cleaning time was set to 10 minutes. The amount of adhesive layer removed (mg) was then calculated by (weight of steel plate after adhesive layer formation - weight of steel plate after cleaning test), and this was divided by the time (minutes) to calculate the removal rate. The results are shown in Figure 6. As shown in Figure 6, the removal rate of the sodium carbonate aqueous solution improved significantly as the liquid temperature increased. It is also possible to shorten the cleaning time when using carbonate by setting the liquid temperature appropriately.

[0049] Test Example 3 The mechanism by which the adhesive layer was removed by carbonate was investigated. 20 mL of each liquid (concentration 0.3 mol / L) was placed in a 50 mL bottle and heated to 90°C. A solid piece of shellac-containing adhesive cut into pieces measuring 3 mm x 3 mm x 10 mm was immersed in the solution, and the process of dissolution of the solid was observed. The results are shown in Table 2. Figure 7 shows the appearance of the solid before immersion, after immersion in the sodium carbonate aqueous solution, and after immersion in the sodium hydroxide aqueous solution.

[0050] [Table 2]

[0051] As is clear from the results in Table 2 and Figure 7, bubbles were generated on the surface of the solid material only in the carbonate aqueous solution. These bubbles are thought to be carbon dioxide produced by the reaction between the acidic components generated from the adhesive and the carbonate. The high removal performance of the carbonate aqueous solution is presumed to be due to the mechanical cleaning power (i.e., bubbling) of these carbon dioxide bubbles. This also explains why the increase in liquid temperature had such a large effect on the carbonate aqueous solution. The higher the temperature, the larger the volume and buoyancy of the bubbles, making it easier for the adhesive components to escape from the gaps between the steel sheets. The movement of the bubbles at this time can act as a mechanical cleaning power.

Claims

1. A method for removing an adhesive layer containing shellac that is interposed between articles, the method comprising using an adhesive layer remover characterized in that (1) the adhesive layer is adhered and fixed to at least one surface of the article, and (2) the remover is an aqueous solution in which at least an alkali metal carbonate is dissolved in water, the method comprising using an adhesive layer remover to remove an adhesive layer in which both the upper and lower surfaces of the flat portion of the adhesive layer are isolated from the outside air by the article, A method for removing an adhesive layer, comprising the step of bringing at least the adhesive layer into contact with the adhesive layer remover at a temperature of 70 to 100°C, thereby dissolving and removing the adhesive layer.

2. A method for removing an adhesive layer as described in claim 1, wherein the minimum thickness of the adhesive layer is 1 mm or less.

3. A method for removing an adhesive layer as described in claim 1 or 2, wherein the concentration of alkali metal carbonate in the aqueous solution is 0.1 mol / L or more.

4. A method for removing an adhesive layer described in any of claims 1 to 3, wherein at least the area of ​​the article that contacts the adhesive layer is metal.

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