JP2009202442A - Release sheet and its manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a release sheet which exhibits a different and improved release force to an adhesives, as compared with a release layer with the same composition by increasing the release force of the light releasable silicone release agent, and is suitable for applications requiring good releasability such as for industrial adhesive labels. <P>SOLUTION: The release sheet comprises a base material sheet and a release layer comprising a silicone composition formed thereon. The surface of the release layer is roughened for increasing the release force to adhesives. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a release sheet used for release paper, pressure-sensitive adhesive labels, pressure-sensitive adhesive tapes, and the like and a method for producing the same.

  In recent years, the demand for adhesives and adhesive tapes has diversified, and various adhesives and adhesive tapes are used for various applications. At present, silicones typified by silicone resin are the mainstream of release agents used on the release surfaces of adhesive labels and adhesive tapes. Generally, the peel strength is very low (light peelability), and the adhesive label can be easily peeled off when used for, for example, a release sheet of an adhesive label.

  However, there is also an important application field in which a release agent that does not easily peel off an article coated with an adhesive, such as an adhesive label, from the release sheet is required. For example, a release agent having a heavy release property is required for affixing industrial adhesive labels that operate at high speed. In order to prevent the adhesive label from prematurely peeling from the release paper, a heavy release silicone release agent is desirable.

  The usual method for forming the release layer is as follows. As a release sheet base material (hereinafter referred to as a base sheet), a paper or plastic film is used, and a silicone composition having heat-curing properties, ultraviolet-curing properties, electron beam-curing properties, etc. as a stock solution of a release agent. Use liquid products. First, in order to improve the adhesive force between the base sheet and the release agent and to prevent the release agent from being excessively infiltrated into the base sheet, pretreatment such as primer treatment is performed on the base sheet as necessary. I do. Next, a liquid material of the silicone composition is applied to the base sheet at a predetermined thickness, the solvent is volatilized as necessary, and then cured by a predetermined method to complete the release sheet.

  The completed release sheet is wound up into a roll and is often stored until use. However, an adhesive layer may be formed on the back surface in a continuous process and wound into a pressure-sensitive adhesive tape. Moreover, the sheet | seat which performed the printing for labels on the peeling surface of a peeling sheet may be piled up and wound up in the continuous process, and it may be set as the original fabric roll for adhesive labels.

  The peel force can be adjusted by changing the silicone composition. For example, a method is known in which non-functional and vinyl-functional silicone resins are used as a peel force adjusting additive. A resin and / or liquid mixture of vinyl functional silicone and SiH functional silicone crosslinker cures in the presence of a noble metal catalyst by a known hydrosilylation addition reaction, but is added to the main component of the silicone composition. By varying the amount of vinyl functional silicone resin, various levels of peel strength can be obtained.

  For example, Patent Document 1 discloses a heat-added overheat-curing release coating composition capable of adjusting the release force in a silicone release coating mainly composed of vinyl-modified silicone. A method is disclosed for adjusting the peel force by adding an epoxy functional silicone resin containing trifunctional or tetrafunctional siloxane units.

  Patent Document 2 discloses a silicone composition obtained by crosslinking of an alkenyl functional polyorganosiloxane and a composition containing SiH functional organosiloxane having an incompatible group of 0.1 to 60 mol%. Methods for adjusting the degree of incompatibility with silicone coating compositions including alkenyl functional polyorganosiloxanes are disclosed.

  Patent Document 3 discloses a method for adjusting the peeling force using a peeling force regulator containing a mixture of a fluorosilicone resin and an alkenyl functional organopolysiloxane as a peeling force regulator for a silicone release coating.

  Patent Document 4 discloses a composition containing a perfluoroalkyl group and a fluorosilicone compound having at least three silicon-bonded hydrogen atoms, and an MQ resin having at least one alkenyl group, and a release modifier. A method of using and adjusting the peel force is disclosed.

  Furthermore, Patent Document 5 discloses a method of adjusting the peeling force by a unique combination of an epoxy functional silicone resin and an epoxy-terminated liquid dimethyl silicone as a peeling force adjusting method for an ultraviolet curable epoxy silicone release agent. Has been.

  However, the peeling composition prepared by the method of adjusting the peeling force by heat curing or ultraviolet curing can be adjusted only by changing the composition, and when a release sheet having a different peeling force is required. In each case, a silicone having a different composition must be prepared.

Patent documents are shown below.
Japanese Patent Laid-Open No. 06-166820 JP-A-11-100551 JP-A-10-195388 JP 09-278893 A JP 07-002976 A

  An object of this invention is to provide the peeling sheet which has different peeling force with respect to an adhesive even if it uses the peeling layer of the same composition. In particular, it is an object of the present invention to provide a release sheet suitable for applications requiring heavy peelability, such as industrial pressure-sensitive adhesive labels, and a method for producing the same by increasing the peel strength of a light-release silicone release agent.

  As a result of diligently studying the above problems, the present inventors have found that even when the silicone release layer has the same composition, the release force is increased by forming irregularities on the surface of the release layer. Furthermore, it has been found that there is a substantially linear proportional relationship between the unevenness and the peeling force. That is, it was found that the peeling force can be controlled by controlling the surface shape without changing the material of the peeling layer, and the present invention has been achieved. The reason why the peeling force increases is thought to be because the surface of the release layer is uneven, increasing the surface area and increasing the area in contact with the adhesive.

  The invention according to claim 1 is a release sheet having at least a base sheet and a release layer made of a silicone composition formed thereon, and has a release layer on the surface of the release layer to provide a release force against the adhesive. It is a release sheet characterized by having increased.

Next, the invention according to claim 2 is the method for producing a release sheet according to claim 1, wherein the method of forming irregularities on the surface of the release layer is applied to a release layer formed on a base sheet. During the curing of the liquid, the method is to transfer the uneven shape on the surface of the object to the surface of the release layer by pressing an object having unevenness on the surface with the liquid for the release layer, and pressurizing it. It is the manufacturing method of the peeling sheet to do.

  Next, the invention according to claim 3 uses a sheet having irregularities on the surface as an object having irregularities on the surface, and the method of pressurizing the sheet is such that the irregular surface and the release layer are in contact with the sheet having irregularities. The method for producing a release sheet according to claim 2, wherein the method is a method in which the sheet is sandwiched and wound up in a roll shape and is pressurized by a pressure in a wound state.

  Next, the invention according to claim 4 is a method in which a substrate sheet having irregularities on one side is used as an object having irregularities on the surface, and the method of pressurizing the substrate is applied to another liquid for forming a release layer. It is the method of apply | coating to a surface, winding up in roll shape, and pressurizing with the pressure in a winding state, It is a manufacturing method of the peeling sheet of Claim 2 characterized by the above-mentioned.

  Next, the invention according to claim 5 uses a substrate sheet having irregularities on both sides as an object having irregularities on the surface, and a method of applying pressure on the surface by applying a liquid for forming a release layer on one surface of the substrate sheet. The method for producing a release sheet according to claim 2, wherein the method is a method of winding in a roll shape and pressurizing with a pressure in a wound state.

  Next, the invention according to claim 6 is the method for producing a release sheet according to claim 2, wherein the object having unevenness is a flat plate or a roll having unevenness formed on the surface.

  Next, the invention according to claim 7 is characterized in that the amount of unevenness on the surface of the release layer is controlled by controlling the amount of unevenness of the object having unevenness on the surface. It is a manufacturing method of the peeling sheet as described in an item.

  The effect of the invention of claim 1 is that the surface area is increased by forming irregularities on the surface of the release layer, and the contact area with the pressure-sensitive adhesive can be increased. As a result, the peel force can be increased. It is a point to become.

  The effect of the invention of claim 2 is that when the release layer is formed, a specific manufacturing method of forming the unevenness on the release layer by bringing the release layer into contact with an object having an uneven surface is provided. is there.

  The effect of the invention of claim 3 is that it provides a method for producing a release sheet having irregularities on the surface of the intended release layer by sandwiching a sheet having irregularities on the surface in the production process of a normal release sheet. is there. The object can be achieved without significantly changing the normal manufacturing process.

  The effect of the invention of claim 4 is that a target release sheet can be manufactured without changing the manufacturing process of a normal release sheet.

  The first effect of claim 5 is that, similarly to claim 4, the target release sheet can be manufactured without changing the normal manufacturing process of the release sheet. The second effect is that since the substrate sheet has unevenness on both sides, the unevenness on the surface to which the release layer is applied also contributes to the formation of unevenness on the surface of the release layer, so that the peel force is increased accordingly. It is.

  The effect of the invention of claim 6 is that a desired uneven surface can be formed by using a plate making technique in printing.

The effect of the invention of claim 7 is that it provides a method for controlling and increasing the peeling force by utilizing the fact that the unevenness of the surface of the peeling layer and the peeling force with respect to the pressure-sensitive adhesive are in a proportional relationship.

  One of the methods of the present invention and the basic effects of the present invention will be described with reference to FIG. In FIG. 1A, a roll 13 is formed by winding a film 11 having a release layer formed on a base sheet together with a film 12 having unevenness. However, it is necessary to wind up while the release layer, which is a silicone composition, can still be plastically deformed. Then, as shown in FIG.1 (b), the peeling layer 2 with which the plasticity on the base material sheet 1 remains plastically deforms according to the unevenness | corrugation of the film 12 with the pressure applied in the wound state. . When the concavo-convex film 12 is pulled away in a state where the release layer is hardened and is no longer plastically deformed, a reverse pattern concavo-convex shape corresponding to the concavo-convex shape of the film 12 is transferred to the release layer 2 as shown in FIG. Is done.

  FIG.1 (d) shows the state by which the adhesive 3 was pushed into the recessed part of the peeling layer, as a result of pressing the peeling sheet 11 of the state of FIG.1 (c) on the adhesive tape 14, and pressing it. Then, the contact area between the pressure-sensitive adhesive and the surface of the release layer is increased by the amount of the recess compared to the case where the release layer is flat. As a result, the peeling force for peeling the release sheet increases. By changing the concavo-convex amount (surface area) of the film 12, the concavo-convex amount (surface area of the release layer) formed on the release layer can be controlled, so that the release force of the release layer can be controlled.

As a representative value of the surface area of the film 12, the present inventors have used an arithmetic average surface roughness Ra (JIS).
When B0601) was used, it was found that there is a substantially linear relationship between Ra and peel force as shown in the Example section.

  The base sheet used in the peeling structure of the present invention is based on plastic films such as polyethylene, polypropylene, polyester, polyvinyl chloride, acetate, cellophane, polycarbonate, polytetrafluoroethylene, polyimide, polystyrene, and paper. Various types of paper such as kraft paper, glassine paper, and crepe paper can be used.

  As a method of applying the liquid of the silicone composition serving as the release layer to these base material sheets, known methods such as roll coating, gravure coating, wire doctor coating, air knife coating, and dipping coating can be employed.

  The thickness of the release layer may be any thickness that does not hinder the formation of irregularities formed on the surface. For example, if it is planned to manufacture a recess having a maximum depth of 3 μm, the thickness of the release layer is at least 3 μm. In addition, when using a substrate sheet having a surface with unevenness, such as paper, the surface can be smoothed with a primer coat or the like, or the thickness of the release layer can be filled with the unevenness It is necessary to add only minutes.

  As the film 12 having irregularities on the surface to be sandwiched, a film having a desired irregular surface can be used first by a normal coating method. That is, it is possible to use a coating obtained by applying a coating liquid in which fine particles are dispersed to a smooth base material and then curing the coating liquid. A desired uneven surface can be formed by changing the size and dispersion amount of the particles.

Moreover, in order to exhibit antiblocking performance, the film which kneaded the minute particle | grains so that an unevenness | corrugation may be formed on the film surface is marketed, and can be used as the film 12. When the amount and size of the kneaded particles are different, the surface irregularity state is different. It is possible to obtain films having various irregular shapes and irregularities. 1 of FIG.1 (b) has shown the cross section of this antiblocking film typically. By changing the degree of unevenness on the surface of the film to be sandwiched, the peeling force of the release sheet can be changed.

  As another manufacturing method of the release sheet of the present invention, as the base sheet 1 of FIG. 1, at least a surface (back surface) on which the release agent is not applied is used, and the surface has unevenness. There is a method of winding the film 12 without sandwiching it. Since the release layer is in contact with the back surface of the substrate sheet in the wound state, the release layer is transferred to the release layer in a shape in which the uneven shape on the back surface of the substrate sheet is reversed.

  Furthermore, as another manufacturing method, there is a method shown in FIG. In FIG. 2, desired irregularities are formed on the surface of the roll 15 by using, for example, a photoetching method. First, the base sheet 14 of the release sheet is unwound from the roll, and the coater 14 is coated with the UV curable release layer solution 2 on the roll 14. Then, the release layer is cured. When it is cured, it is wound up to form a roll 16.

  The method of FIG. 2 is basically a kind of printing method in a broad sense, and is used, for example, when an embossed film is manufactured. Various printing techniques can also be used. For example, a solution for a heat curable release agent, not an ultraviolet curable type, can be used. In that case, it heats in the part which overlapped with the roll. Further, when it is necessary to volatilize the solvent, the solvent is volatilized after being applied and heated by passing through a heater. Moreover, the formation of the unevenness | corrugation of the surface of the roll 15 can use the method of producing a gravure printing roll, and the method of producing a resin relief printing plate.

  Moreover, although the roll which formed the uneven | corrugated pattern in FIG. 2 is used, it can use by forming an unevenness | corrugation in a flat plate. In that case, for example, a hot stamping method can be used as a method of pressurizing the layers. That is, it is a method in which a base material sheet coated with a thermosetting release agent is intermittently sent, and the release layer is cured by applying pressure and heating in a state of being overlapped with a flat plate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited at all by these Examples.

Example 1
A polypropylene film having a film thickness of 100 μm was used as a base sheet, and a release layer made of a silicone composition was produced thereon as follows. That is, 100 parts by mass of silicone TPR6500 (made by Momentive Performance Materials Japan LLC) for UV curable release paper and 1 part by mass of curing agent UV9380C (made by Momentive Performance Materials Japan LLC) Was applied to a thickness of 1 μm and cured for a predetermined time using a 120 W / cm halogen lamp to form a release layer.

  When the polypropylene film having the release layer is wound up to produce a roll, an antiblocking agent composed of zeolite particles having an average particle diameter of 10 μm is added to (A) 0.5 mass%, (B) 1 mass%, and (C). Three types of anti-blocking polypropylene films having a thickness of 20 μm and containing 2% by mass were sandwiched sequentially and wound into a roll (see FIG. 1A). Moreover, when winding up the polypropylene film which has a peeling layer, the case where a blocking prevention film was not pinched | interposed between it was made into the comparative example (no film).

(Measurement of peel force)
The peeling force of the obtained polypropylene film having a release layer was measured by the following method. A pressure-sensitive adhesive tape specified by JIS was pasted on the release layer, and was reciprocated once with a pressure roll having a mass of 5 kg. After 16 hours at 40 ° C., the peel strength at 180 degrees was measured according to JIS K-6854. . The peeling speed was 300 mm / min. The measurement results of the peeling force are shown in Table 1. The degree of unevenness on the surface of the release layer is represented by Ra. Ra is a numerical value indicating the roughness of the object surface defined by JIS B0601. Ra is considered to be a kind of alternative value indicating the surface area of the object when viewed microscopically.

As shown in Table 1, when winding a polypropylene film having a release layer, the release layer was able to improve the release force by sandwiching a film having irregularities with an antiblocking agent. From this result, it was shown that the peeling force of the peeling layer can be adjusted by the amount of the antiblocking agent.

(Example 2)
As a base sheet, a polypropylene film having a smooth film thickness of 100 μm and comprising no zeolite anti-blocking agent having an average particle size of 10 μm, (A) 0.5 mass%, (B) 1 mass%, (C) 2 mass% An antiblocking polypropylene film having a film thickness of 100 μm was used, and a release layer made of a silicone composition having the same composition as that of Example 1 was coated thereon so as to have a film thickness of 1 μm. The polypropylene film having the release layer was wound up in a spiral shape to produce a roll.

(Measurement of peel force)
The peeling force of the polypropylene film having the obtained release layer was evaluated as follows. A 1-inch wide adhesive tape specified by JIS is pasted on the release layer, one-way reciprocating with a pressure roll with a mass of 5 kg, and after 16 hours at 40 ° C., peeled off by 180 degrees according to JIS K-6854. The force was measured. The peeling speed was 300 mm / min. Table 2 shows the measurement results of the peeling force.

As shown in Table 2, it was possible to improve the peeling force of the release layer by forming and winding the release layer using a film having projections and depressions with an antiblocking agent on the base sheet. From this result, it was shown that the peeling force of a peeling layer can be adjusted with the amount of antiblocking agents in a base material sheet.

  FIG. 3 illustrates the results of Table 1 and Table 2. In both cases, the peel force increases linearly in proportion to the amount of fine particles (zeolite) kneaded into the anti-blocking film. From this result, it is considered that the amount of fine particles is proportional to the surface roughness of the anti-blocking film, that is, the surface area. Moreover, it is thought that the unevenness | corrugation of the surface of an antiblocking film respond | corresponds to the unevenness | corrugation of the surface of a peeling layer on a one-to-one basis. Therefore, a desired peeling force can be obtained by selecting the degree of unevenness (Ra value) on the surface of the sandwiched paper.

  In Example 1 and Example 2, even when antiblocking films having the same product number are used, the surface roughness of the obtained release layer is different. The reason for this is that in Example 1, the unevenness of the release layer reflects only the unevenness of the surface of the superposed antiblocking film, but in Example 2, the release layer is as thin as 1 μm. This is considered to be due to the unevenness of the blocking film used as a base sheet as well as the unevenness of the blocking film superimposed.

In Example 2, when a film having an antiblocking agent amount of 2% is used, the surface roughness of the release layer is slightly lower than the straight line on which the other three examples are placed. On the other hand, in Example 1, it is on a straight line. The reason for this difference is not clear, but in Example 2, the details of the irregularities on the surface of the blocking film overlapped with the release layer did not enter, and as a result, the irregularities on the surface of the blocking film were not completely transferred. Conceivable.

  In FIG. 4, the peeling force with respect to the surface roughness of the peeling layer of Table 1 and Table 2 was shown collectively. In FIG. 4, even if the method of forming the unevenness is different, the test results of the surface roughness and the peeling force are arranged almost on one straight line. This result shows that the peel force can be increased almost proportionally by increasing the surface roughness of the release layer. From this result, the present invention has been reached.

  However, the peel force cannot be increased to any extent, and in FIG. 1 (d), it differs depending on how much the adhesive material can enter the fine portions of the unevenness of the release layer, and is saturated when it cannot enter. . Actually, the peeling force could be increased about 3 times in Example 1 and about 4 times in Example 2.

  In FIG. 4, except for the case where the surface roughness Ra = 1.9 μm, they are arranged almost on a straight line. The reason why the peeling force expected in the case of 1.9 μm cannot be obtained is not clear, but it is considered that the pressure-sensitive adhesive could not enter the entire surface of the unevenness of the peeling layer.

  To further increase the peeling force, firstly increase the surface roughness (Ra value) of the object to be overlapped with the release layer, and secondly, when the release layer is overlapped with the surface having an unevenness and pressed. Decrease the viscosity of the release layer so that the release layer enters into the details of the recesses. Third, increase the pressure when bonding with the adhesive so that the adhesive enters the details of the recesses in the release layer. It is considered necessary to do.

  According to the present invention, since the peeling force of the peeling layer can be controlled without changing the composition of the peeling layer, various peeling forces required in the industry can be dealt with inexpensively and quickly.

It is the schematic for demonstrating the outline and effect of one Example of this invention. It is the schematic for demonstrating another manufacturing method of the peeling sheet of this invention. It is a figure for demonstrating the result of Example 1 and Example 2. FIG. It is a figure for demonstrating the effect of this invention from the result of Example 1 and Example 2. FIG.

Explanation of symbols

1: Base sheet for release sheet 2: Release layer 3: Adhesive 4: Base sheet for adhesive tape 11: Substrate sheet coated with release layer liquid 12: Uneven film 13: Winding roll 14: Adhesive Tape 21: Base sheet winding roll for release sheet 22: Coating device 23: Roll having irregularities on the surface 24: Ultraviolet irradiation device 25: Release sheet winding roll

Claims (7)

  A release sheet having at least a base sheet and a release layer made of a silicone composition formed thereon, wherein the release layer has unevenness on the surface of the release layer to increase the release force against the adhesive. Sheet.   The method for producing a release sheet according to claim 1, wherein the method of forming irregularities on the surface of the release layer is performed while the liquid for forming the release layer applied on the substrate sheet is cured. A method for producing a release sheet, characterized in that an object having a surface is superimposed on a release layer liquid and pressed to transfer the irregular shape of the surface of the object to the surface of the release layer.   Using a sheet with irregularities on the surface as an object with irregularities on the surface, the method of pressurizing the sheet is rolled up by sandwiching the sheet with irregularities so that the irregular surface and the release layer are in contact, The method for producing a release sheet according to claim 2, wherein the release sheet is pressurized by a pressure in a wound state.   Using a base sheet with irregularities on one side as an object with irregularities on the surface, and applying pressure by overlapping, the liquid for forming the release layer is applied to the other side of the base sheet, wound up in a roll shape, The method for producing a release sheet according to claim 2, wherein the release sheet is pressurized by a pressure in a wound state.   Using a substrate sheet with irregularities on both sides as an object with irregularities on the surface, and applying pressure by overlapping, the liquid for forming the release layer is applied to one surface of the substrate sheet, wound into a roll, and wound up The method for producing a release sheet according to claim 2, wherein the method is a method of applying pressure by pressure in a state.   The method for producing a release sheet according to claim 2, wherein the object having surface irregularities is a flat plate or a roll having irregularities formed on the surface.   The method for producing a release sheet according to any one of claims 2 to 6, wherein the unevenness amount of the surface of the release layer is controlled by controlling the unevenness amount of an object having unevenness on the surface.