JP6601921B2 - Release adhesive tape - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive tape that is useful for mold release, for example, in a molding method in which a fiber-reinforced prepreg is laminated, heated and pressed and cured to obtain a molded product of fiber-reinforced plastic (FRP).

  Fiber reinforced plastic (FRP) made by impregnating and curing a base material (matrix) such as epoxy resin into reinforcing fibers such as glass fiber, carbon fiber, and aramid fiber is lightweight but has high strength characteristics, fatigue resistance, Since it has excellent properties such as moldability and chemical resistance, it is widely used in various applications such as electrical / electronic equipment, automobile equipment, sports equipment, aerospace industry and the like.

  As a typical method for producing FRP, there is known a molding method in which a continuous reinforced fiber is laminated with a fiber reinforced prepreg impregnated with an uncured resin, and is heated and cured. There is a method of applying a release agent such as wax to the press surface in order to improve the release property between the press surface of the mold and the FRP. However, in the method of applying a release agent such as wax to the press surface, the release effect is reduced each time the molding is repeated. Therefore, it is necessary to apply the release agent every time molding is performed, which is disadvantageous in terms of work time and cost. It is. In addition, a release agent may adhere to the surface of the obtained molded product, which may adversely affect post-processing of the molded product such as bonding and painting. A general method for removing the attached release agent is to grind the surface layer of the molded product with sandpaper or a polishing machine. It is disadvantageous. Further, Patent Document 1 discloses a method of cleaning the release agent by treating the surface of a molded product with a corona flame or a plasma flame, but this method further requires expensive equipment for performing the treatment. Become.

  On the other hand, there is a method using a release film instead of the release agent. For example, Patent Document 2 discloses a release film including a release layer formed of a C1-4 alkylated melamine-formaldehyde resin. However, the release film disclosed here is not an adhesive tape because it does not have an adhesive layer. Furthermore, this method is not a method of continuously performing molding a plurality of times while the release film is adhered to the press surface side, but a release film is installed between the prepreg and the press surface for each molding. After the molding, the release film is peeled off from the surface of the molded product. Therefore, it is disadvantageous in terms of working time and cost.

  Patent Document 3 discloses a release pressure-sensitive adhesive tape having a base layer made of a polytetrafluoroethylene rolled base film and an adhesive layer. Patent Document 4 discloses a heat sealer in which both ends of the width of the fluororesin tape are bonded to the end of the heat radiation bar with an adhesive. Patent Document 5 discloses a fluororesin adhesive tape having a base material made of a fluororesin film and an adhesive layer. However, the pressure-sensitive adhesive tape for release of Patent Document 3 is used for preventing the melt-extruded resin from adhering to the laminate roll, and the tape made of fluororesin of Patent Document 4 is used for a heat sealer. The fluororesin adhesive tape of Patent Document 5 is used for heat-resistant binding of coils and motors, roll protection of laminators and coaters, or heat-resistant release for heat sealing. Therefore, the tape of patent documents 3-5 is not examined about the mold release use in the hot press molding of fiber reinforced prepreg.

  In addition to the tapes described in Patent Documents 3 to 5, various types of pressure-sensitive adhesive tapes having a base material made of a fluororesin and a pressure-sensitive adhesive layer have been commercially available. However, when such a general adhesive tape is used for mold release in hot press molding of fiber reinforced prepreg, it is hot pressed at high temperature. It will stick to. When the next hot press molding is performed on the tape with the uneven marks as it is, the uneven marks are transferred to the surface of the formed product, which adversely affects the appearance of the formed product. In addition, the reinforcing fibers in the prepreg are lifted on the surface by pushing out the matrix resin due to uneven marks, and this also adversely affects the appearance of the molded product. Since the adhesive tapes for release described in Patent Documents 3 to 5 have different uses, such problems have not been studied at all.

JP 2003-221458 A JP 2014-151448 A JP 2004-83706 A JP 2000-203529 A JP-A-8-253740

  An object of the present invention is to provide a pressure-sensitive adhesive tape for mold release that does not have uneven marks on the release surface of the tape even when hot-pressed at a high temperature, and a molded product having a good appearance can be obtained even if continuously molded. It is in.

The present invention relates to a release pressure-sensitive adhesive tape having at least a fluororesin-based film for forming a release surface and an adhesive layer, wherein the adhesive layer has a silicone-based adhesive or a softening point of 150 ° C. A pressure-sensitive adhesive for mold release comprising a pressure-sensitive adhesive composition containing an acrylic pressure-sensitive adhesive exceeding 80, and having a type 00 durometer hardness defined by ASTM D 2240 of 60 or higher at 23 ° C. and 30 or higher at 150 ° C. It is a tape.

  Since the pressure-sensitive adhesive tape for mold release of the present invention has the specific configuration as described above, even if it is hot-pressed at a high temperature, the release surface of the tape does not have uneven marks, and it has a good appearance even if it is continuously molded as it is. A molded product having is obtained.

It is typical sectional drawing which shows one Embodiment of the adhesive tape for mold release of this invention.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of the pressure-sensitive adhesive tape for release of the present invention. In this embodiment, the adhesive layer 2 is provided on one surface of the fluororesin-based film 1 for constituting the release surface. In addition, an application tape 3 is laminated on the other surface (release surface) of the fluororesin film 1, and a release liner 4 is laminated on the surface of the adhesive layer 2 opposite to the fluororesin film 1. Yes.

  The release pressure-sensitive adhesive tape shown in FIG. 1 is a preferred embodiment of the present invention, but the present invention is not limited to this. For example, the release pressure-sensitive adhesive tape of the present invention does not necessarily have the application tape 3 and does not necessarily have the release liner 4. Further, FIG. 1 shows a configuration in which the fluororesin film 1 functions as a base material for the adhesive tape. For example, a base material other than the fluororesin film 1 is interposed between the fluororesin film 1 and the adhesive layer 2. You may do it.

[Fluororesin film 1]
The fluororesin film 1 in the present invention is not particularly limited, and various fluororesin films that are known to be usable for mold release can be used. The fluororesin film 1 may be a film made of a homopolymer of a fluororesin monomer, or a film made of a copolymer having a fluororesin monomer as a main structure and including other monomer structures. There may be. Moreover, the film which consists of a composition which has a fluororesin as a main component and also contains other resin may be sufficient. Furthermore, a known additive may be included.

  Specific examples of the fluororesin include tetrafluoroethylene resin (PTFE), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (PFEP), and tetrafluoroethylene. -Perfluoroalkyl vinyl ether copolymer (PFA), trifluorochloroethylene resin (PCTFE), vinylidene fluoride resin (PVDF), and vinyl fluoride resin (PVF). Of these, tetrafluoroethylene resin (PTFE) and tetrafluoroethylene-ethylene copolymer (ETFE) are preferable.

  In addition to the fluororesin film 1, examples of conventional films used for mold release include silicone-coated polyethylene terephthalate films, polymethylpentene films, and polypropylene films. However, in the silicone-coated polyethylene terephthalate film, the silicone component may migrate, and the same problem as when a release agent is applied to the press surface may occur. The polymethylpentene film is excellent in releasability, but the film is easily wrinkled during molding. Polypropylene film has low heat resistance and insufficient releasability. On the other hand, the fluororesin film 1 used in the present invention does not have such a problem.

  Although the thickness of the fluororesin-type film 1 is not specifically limited, Preferably it is 3-200 micrometers, More preferably, it is 3-60 micrometers. In particular, by making the fluororesin film 1 moderately thin, uneven marks are less likely to be attached to the release surface even when hot pressing is performed. In addition, in the mold release use of a hot press, it is generally considered that the fluororesin film is preferably thicker. Therefore, the fact that a relatively thin fluororesin film as in the present invention provides an excellent effect is an unexpected effect for those skilled in the art. On the other hand, if the thickness is too thin, the bending moment (waist) of the adhesive tape will be weak, for example, the film will curl and difficult to stick to the adherend, causing creases or adhesion when sticking to the adherend Air bubbles tend to remain between the surfaces. However, this point can be improved by, for example, laminating the application tape 3 on the release surface to increase the bending moment (waist) of the adhesive tape.

  The surface on which the pressure-sensitive adhesive layer 2 of the fluororesin film 1 is provided may be subjected to an easy adhesion treatment as necessary. Examples of the easy adhesion treatment include primer treatment, corona treatment, etching treatment, and plasma treatment.

[Adhesive layer 2]
The pressure-sensitive adhesive layer 2 in the present invention is a layer made of a pressure-sensitive adhesive composition. And the type 00 durometer hardness prescribed | regulated by ASTM D 2240 of this adhesive composition is 60 or more in 23 degreeC, Preferably it is 75 or more, and is 30 or more in 150 degreeC, Preferably it is 35 or more. In this way, if the durometer hardness is particularly high at a high temperature (150 ° C.), even if heat-pressed under high temperature conditions, the mold release surface of the tape does not have uneven marks, and it has a good appearance even if it is continuously molded as it is. Goods are obtained. In addition, if the durometer hardness at normal temperature (23 ° C.) is high, the bending moment (waist) of the tape will be moderately strong and tend to be attached to the adherend.

  Specifically, the durometer hardness is a value obtained by laminating the pressure-sensitive adhesive composition until the thickness becomes 6 mm and measuring this as a measurement sample, as described in Examples described later.

Adhesive composition includes a silicone adhesive or an acrylic adhesive. In particular, a silicone pressure-sensitive adhesive is preferable from the viewpoint of heat resistance.

Specific examples of the silicone-based pressure-sensitive adhesive include silicone raw rubber (polydimethylsiloxane long-chain polymer mainly composed of D units [(CH ₃ ) ₂ SiO]) and MQ resin (M units [(CH ₃ ) ₃ SiO). _1/2] the adhesive comprising a polymer) of a silicone resin having a three-dimensional structure consisting of Q units [SiO _2] and the like. Such a pressure-sensitive adhesive composed of a raw silicone rubber and an MQ resin is superior in adhesiveness compared to a silicone raw rubber alone. Examples of the silicone-based pressure-sensitive adhesive include addition-curable silicone pressure-sensitive adhesives and peroxide-curable pressure-sensitive adhesives. Two or more types of silicone pressure-sensitive adhesives may be used in combination.

There are various methods for setting the durometer hardness of the pressure-sensitive adhesive layer 2 to the specific high value described above. When using a silicone-based pressure-sensitive adhesive, for example, the amount of low-molecular components such as silicone oil contained in the pressure-sensitive adhesive is reduced, or the amount of Q resin (that is, Q unit [SiO ₂ ]) that affects hardness is reduced. There are ways to do more. When using an acrylic adhesive, for example, a method of increasing the glass transition point or softening point of the acrylic resin. In particular, the softening point needs to exceed at least 150 ° C. Further, the durometer hardness can be adjusted by appropriately selecting the type and amount of additives described later to be added to the pressure-sensitive adhesive composition.

  Additives may be added to the pressure-sensitive adhesive composition for the purpose of improving various properties such as the durometer hardness of the pressure-sensitive adhesive layer 2, shear storage modulus G ′, and adhesiveness. Specific examples of additives include inorganic fillers such as carbon black and silica; polyorganosiloxanes such as silicone resin, polydimethylsiloxane and polydimethylphenylsiloxane; and antioxidants such as phenolic antioxidants and amine antioxidants. Agents; silane coupling agents.

  The pressure-sensitive adhesive composition used in the present invention can be obtained using a commercially available product. For example, a commercially available silicone-based pressure-sensitive adhesive is cured using a curing catalyst such as a platinum catalyst to obtain a pressure-sensitive adhesive composition having desired physical properties. In the case of an acrylic pressure-sensitive adhesive, a pressure-sensitive adhesive composition having desired physical properties is obtained by curing using a curing agent such as an isocyanate-based curing agent or an epoxy-based curing agent.

  The pressure-sensitive adhesive layer 2 can be formed, for example, by applying a pressure-sensitive adhesive composition to one side of the fluororesin-based film 1 and curing it using a curing catalyst or a curing agent as described above. In order to lower the viscosity of the pressure-sensitive adhesive composition during application, a solvent may be added. Specific examples of the solvent include aromatic solvents such as toluene and xylene; aliphatic solvents such as hexane, octane and isoparaffin; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ester solvents such as ethyl acetate and isobutyl acetate. An ether solvent such as diisopropyl ether and 1,4-dioxane; The coating method is not particularly limited, and a known method may be used. Specific examples include coating using a comma coater, lip coater, roll coater, die coater, knife coater, blade coater, rod coater, kiss coater or gravure coater; screen coating; dip coating; cast coating. It is done.

  Although the thickness of the adhesive layer 2 is not specifically limited, Preferably it is 3-100 micrometers, More preferably, it is 3-80 micrometers.

[Application tape 3]
In the present invention, the application tape 3 is a tape that is laminated in advance on the release surface side in order to give an appropriate bending moment (waist) when the adhesive tape has a weak bending moment (waist) and is difficult to stick to an adherend. is there. Specifically, it is laminated to improve the ease of work when attaching the release adhesive tape to the adherend, and it is peeled off to expose the release surface after application. Is.

  The type of application tape 3 is not particularly limited, and a known application tape can be used. Specific examples thereof include those obtained by applying a pressure sensitive adhesive such as a rubber pressure sensitive adhesive, an acrylic pressure sensitive adhesive, or a silicone pressure sensitive adhesive to one surface of a base material such as fine paper, glassine paper, or synthetic resin film. In order to prevent the release adhesive tape itself from being peeled off from the adherend when the application tape 3 is peeled off, it is preferable to select one having a sufficiently weak peeling force against the release surface.

[Release liner 4]
In the present invention, the release liner 4 is for protecting the pressure-sensitive adhesive layer 2 of the pressure-sensitive adhesive tape, and is peeled off immediately before application, exposing the pressure-sensitive adhesive layer 2 and applying the pressure-sensitive adhesive tape to the adherend.

  The kind of release liner 4 is not particularly limited, and a known release liner can be used. Specific examples thereof include those obtained by subjecting the surface of a base material such as fine paper, glassine paper, and synthetic resin film to a release agent treatment. For the release agent treatment, for example, a release agent such as a silicone resin or a fluorine-substituted alkyl-modified silicone resin may be used. In particular, the release liner to be laminated on the silicone-based pressure-sensitive adhesive layer is preferably one obtained by releasing the surface of a polyethylene terephthalate film with a fluorine-substituted alkyl-modified silicone resin.

[Release adhesive tape]
As described in the examples described later, the release adhesive tape of the present invention was obtained by cutting two release adhesive tapes into 38 mm × 70 mm, and bonding the adhesive layers together to form a test piece. The bending moment defined by JIS P 8125 of the piece is preferably 2.0 mN · m or more, more preferably 2.4 to 10 mN · m. By having such a bending moment (waist), the ease of attachment is improved.

  The pressure-sensitive adhesive tape for release of the present invention is useful as a pressure-sensitive adhesive tape for release for accelerating releasability between a press die and a molded product, for example, when continuously hot press-molding at a high temperature. . The temperature of the hot press is preferably 40 to 250 ° C, more preferably 150 to 200 ° C. In particular, in a method of manufacturing a fiber reinforced plastic (FRP) molded article by laminating a prepreg impregnated with an uncured resin in a reinforced fiber and curing it by heat pressing, it is affixed to the press surface of a press die. Therefore, it is very useful for the purpose of improving the releasability of the molded product from the press surface.

  The fiber reinforced plastic (FRP) is obtained by impregnating and curing a base material (matrix) such as an epoxy resin in reinforcing fibers such as glass fiber, carbon fiber, and aramid fiber.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. In the following description, “part” means “part by mass”.

<Example 1>
100 parts by weight of an addition curable silicone adhesive stock solution (trade name SD4584, manufactured by Toray Dow Corning Silicone Co., Ltd.) having a solid concentration of 60% by weight, 50 parts of toluene as a diluting solvent, and a platinum catalyst (trade name NC-25, 0.9 parts of Toray Dow Corning Silicone Co., Ltd.) were uniformly mixed to obtain an adhesive liquid (1).

  Next, the pressure-sensitive adhesive liquid (1) was applied to one side of a primer-treated 51 μm-thick tetrafluoroethylene resin (PTFE) film so that the thickness after drying was 25 μm, and the temperature was 130 ° C. in a drying oven. And dried to form an adhesive layer. A release liner (50 μm thick PET film treated with a release agent with a fluorine-substituted alkyl-modified silicone resin) was bonded to the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive tape for release.

<Example 2>
Addition-curing silicone adhesive stock solution (trade name KR-3700, manufactured by Shin-Etsu Chemical Co., Ltd.) having a solid content concentration of 60% by mass, toluene 50 parts as a diluent solvent, platinum catalyst (trade name CAT-PL-) 0.5 part (50T, manufactured by Shin-Etsu Chemical Co., Ltd.) was uniformly mixed to obtain an adhesive liquid (2). And the adhesive tape for mold release was obtained by the method similar to Example 1 except having used the adhesive liquid (2).

<Example 3>
100 parts of an acrylic adhesive stock solution (acrylic copolymer (A)) described in Production Example 1 of International Publication No. 2014/002203, 67 parts of toluene as a diluting solvent, an isocyanate curing agent (trade name Coronate L-45E) 0.6 parts of Tosoh Corporation) and 10 parts of an epoxy curing agent (trade name E-5XM, manufactured by Soken Chemical Co., Ltd.) were uniformly mixed to obtain an adhesive liquid (3).

  Next, the adhesive liquid (3) was applied to one side of a 51 μm-thick PTFE film so that the thickness after drying was 25 μm. This was dried at 60 ° C. in a drying oven to remove the solvent, and further dried at 130 ° C. to crosslink and cure the pressure-sensitive adhesive to form a pressure-sensitive adhesive layer. Then, the release liner was bonded to the pressure-sensitive adhesive layer and cured at 40 ° C. to obtain a release pressure-sensitive adhesive tape.

<Example 4>
An application tape (polyethylene film adhesive tape, trade name PSPE9493, manufactured by Teraoka Seisakusho Co., Ltd.) having a thickness of 63 μm is pasted on the release surface of the release adhesive tape obtained in Example 1 for release with application tape. An adhesive tape was obtained.

<Comparative Example 1>
Addition-curing silicone adhesive stock solution (trade name SD4592, manufactured by Toray Dow Corning Silicone Co., Ltd.) having a solid content concentration of 60% by mass, 50 parts of toluene as a diluent, and a crosslinking agent (trade name BY-24-741, Toray Industries, Inc.) 1.0 part of Dow Corning Silicone Co., Ltd.) and 0.9 part of a platinum catalyst (trade name NC-25, manufactured by Toray Dow Corning Silicone Co., Ltd.) as a curing catalyst are uniformly mixed to obtain an adhesive solution (4) Got. And the adhesive tape for mold release was obtained by the method similar to Example 1 except having used the adhesive liquid (4).

<Comparative Example 2>
100 parts of a peroxide curable silicone adhesive stock solution (trade name SH4280, manufactured by Toray Dow Corning Silicone Co., Ltd.) having a solid concentration of 60% by mass, 50 parts of toluene as a diluent, and benzoyl peroxide (Nyper (registered) as a crosslinking agent) (Trademark) BMT-40 (manufactured by NOF Corporation) (3.0 parts) was uniformly mixed to obtain an adhesive liquid (5).

  Next, the pressure-sensitive adhesive liquid (5) was applied to one surface of a 51 μm-thick PTFE film subjected to primer treatment so that the thickness after drying was 25 μm. This was dried at 60 ° C. in a drying oven to remove the solvent, and further dried at 180 ° C. to crosslink and cure the pressure-sensitive adhesive to form a pressure-sensitive adhesive layer. And a release liner was bonded together to the adhesive layer, and the adhesive tape for mold release was obtained.

<Comparative Example 3>
Acrylic adhesive stock solution having a solid content concentration of 43% by mass (SK Dyne (registered trademark) 1717DT, manufactured by Soken Chemical Co., Ltd.), 10 parts of toluene as a diluent, isocyanate curing agent (trade name Coronate L-45E, Tosoh Corporation 2.1 parts (made by company) were mixed uniformly to obtain a pressure-sensitive adhesive liquid (6). And the adhesive tape for mold release was obtained by the method similar to Example 3 except having used the adhesive liquid (6).

<Example 5>
A pressure-sensitive adhesive tape for mold release was obtained in the same manner as in Example 1, except that a PTFE film having a thickness of 82 μm was used.

<Example 6>
A release adhesive tape was obtained in the same manner as in Example 1 except that a PTFE film having a thickness of 25 μm was used.

<Example 7>
A release adhesive tape with an application tape was obtained in the same manner as in Example 4 except that the release adhesive tape obtained in Example 6 was used.
The above Examples and Comparative Examples were evaluated according to the following methods. The results are shown in Tables 1 and 2.

<Durometer hardness of adhesive composition>
The pressure-sensitive adhesive solution was applied on the release liner so that the thickness after drying was 50 μm. Then, it heated and dried with the drying furnace, and it was set as the adhesive composition, and this was laminated | stacked until it became thickness 6mm, and it was set as the measurement sample. The heating temperature was the same as in each example and comparative example. That is, in the case of the adhesive liquid (1), (2), (4), the adhesive liquid (3), in the case of (6), 60 ° C and 130 ° C, in the case of the adhesive liquid (5) The temperature was 60 ° C and 180 ° C. This 6 mm thick sample was stored in an environment of 23 ° C., and the type 00 durometer hardness (23 ° C.) defined by ASTM D 2240 was measured. Further, the sample was stored in a dryer at 150 ° C. and 200 ° C. for 2 hours, and the type 00 durometer hardness (150 ° C. and 200 ° C.) defined by ASTM D 2240 was measured.

<Maximum height Rz of adhesive tape surface before and after molding>
Two SUS plates to which an adhesive tape cut to 5 cm × 5 cm was attached were prepared. Based on JIS B 0601 (2001), the maximum height Rz of the pressure-sensitive adhesive tape surface (mold release surface) before molding was measured. Next, a carbon fiber 3K plain weave prepreg (cured at 130 ° C., 333 g / cm ² basis weight (fiber 200 g, epoxy resin 133 g)) was cut into a size of 3 cm × 3 cm. Next, five prepregs were laminated and sandwiched between two SUS plates (molds) to which a release adhesive tape was attached. And it heat-pressed for 20 minutes at the temperature of 150 degreeC and the pressure of 5 kg / cm < ² >, and the molded article of the carbon fiber reinforced plastic (CFRP) was obtained. Furthermore, after repeating this molding once more, the maximum height Rz of the pressure-sensitive adhesive tape surface (release surface) was measured in the same manner as before molding.

<Degree of unevenness on the surface of the molded product>
In the measurement of the maximum height Rz, the surface of a molded product of carbon fiber reinforced plastic (CFRP) obtained by molding the second time was traced with a finger, and the degree of unevenness was evaluated according to the following criteria based on the touch.
“O”: Almost no unevenness.
“△”: Slightly uneven.
“×”: There is a clear unevenness.

<Normal SUS adhesive strength>
The pressure-sensitive adhesive tape cut to a width of 20 mm was attached to a polished SUS plate, pressed once by a roller covered with a rubber layer having a weight of 2 kg, and allowed to stand at 23 ° C. for 20 to 40 minutes. Thereafter, the force required to peel the tape at an angle of 180 ° at a speed of 300 mm / min was measured using a tensile tester.

<Adhesion to SUS after heating>
The pressure-sensitive adhesive tape cut to a width of 20 mm was attached to a polished SUS plate, pressed once by a roller covered with a rubber layer having a weight of 2 kg, and left in a dryer at 180 ° C. for 2 hours. This was taken out and allowed to cool at room temperature, and the force required to peel off the tape at an angle of 180 ° at a speed of 300 mm / min was measured using a tensile tester. Further, the presence or absence of foaming of the pressure-sensitive adhesive layer after heating and the presence or absence of adhesive residue on the adherend after peeling were visually observed.

<Peeling force of application tape>
The adhesive tape with application tape was attached to a polished SUS plate. Then, using a tensile tester, the force required to peel the application tape from the release surface at an angle of 180 ° at a speed of 300 mm / min was measured.

<Bending moment>
Two adhesive tapes were cut into 38 mm × 70 mm, and the adhesive layers were bonded together to obtain a test piece. And the bending moment prescribed | regulated by JISP8125 was measured using the Taber rigidity tester.

<Ease of pasting>
The adhesive tape cut to 50 mm × 50 mm was attached to a polished SUS plate. The ease of pasting at that time was evaluated according to the following criteria.
“◯”: Easy to paste.
“×”: Hard to paste.

<Evaluation results>
As shown in Table 1, in Examples 1 to 4, molded articles having good appearance quality with no unevenness on the surface and almost no unevenness on the surface were obtained at the time of molding. On the other hand, in Comparative Examples 1 to 3, since the durometer hardness at high temperature (150 ° C.) is low, the release surface of the adhesive tape has uneven marks, and the surface of the obtained molded product has a distinct uneven feeling. there were. Furthermore, in Examples 1-4, the adhesive tape which is easy to affix on a to-be-adhered body was obtained. On the other hand, in Comparative Examples 2 and 3, since the durometer hardness at normal temperature (23 ° C.) was low, an adhesive tape having a weak bending moment and difficult to stick was obtained.

The reason why the durometer hardness at high temperature is low in Comparative Example 1 is that the amount of low-molecular components such as silicone oil contained in the used silicone adhesive (SD4592) is in the silicone adhesive (SD4584) used in Example 1. Compared to many, this low molecular component promotes softening of the pressure-sensitive adhesive layer at high temperatures. Moreover, the reason why the durometer hardness at normal temperature and high temperature in Comparative Example 2 is low is that the amount of Q resin (ie, Q unit [SiO ₂ ]) contained in the used silicone adhesive (SH4280) is used in Example 1. Compared to the silicone adhesive (SD4584), the hardness improving effect of the Q resin is small. Moreover, the reason why the durometer hardness at a normal temperature and a high temperature in Comparative Example 3 is low is that the acrylic adhesive used in Example 3 has a glass transition point and a softening point of the used acrylic adhesive (SK Dyne (registered trademark) 1717DT). Is at a lower point.

  In Example 3, since an acrylic pressure-sensitive adhesive is used, the adhesive strength is slightly inferior to those in Examples 1 and 2. However, since the durometer hardness is high, the appearance quality with almost no unevenness on the surface is good. It is superior to Comparative Examples 1 to 3 in that a product is obtained.

  As shown in Table 2, in Example 5, the thickness of the fluororesin-based film is as thick as 80 μm, so that the molded tape has a slight unevenness on the release surface of the pressure-sensitive adhesive tape at the time of molding, and the surface has a slightly uneven feeling. was gotten. However, the unevenness is less than the surface of the molded products of Comparative Examples 1 to 3.

  In Example 6, since the thickness of the fluororesin film was as thin as 25 μm, an adhesive tape having a weak bending moment (waist) and difficult to stick was obtained. However, a molded product with good appearance quality was obtained in which the release surface of the pressure-sensitive adhesive tape was not marked on the release surface during molding, and the surface had almost no unevenness. In Example 7, an application tape was further laminated on the adhesive tape of Example 6, an appropriate bending moment was given by the application tape, and an adhesive tape that was easy to stick to an adherend was obtained.

  The pressure-sensitive adhesive tape for release of the present invention is useful as a pressure-sensitive adhesive tape for release for accelerating releasability between a press die and a molded product, for example, when continuously hot press-molding at a high temperature. . In particular, in a method of manufacturing a fiber reinforced plastic (FRP) molded article by laminating a prepreg impregnated with an uncured resin in a reinforced fiber and curing it by heat pressing, it is affixed to the press surface of a press die. Therefore, it is very useful in applications for improving the release property of the molded product from the press surface.

1 Fluororesin film 2 Adhesive layer 3 Application tape 4 Release liner

Claims (7)

A pressure-sensitive adhesive tape for release having at least a fluororesin film for forming a release surface and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is a silicone pressure-sensitive adhesive or an acrylic type having a softening point exceeding 150 ° C. A pressure-sensitive adhesive tape for mold release comprising a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive and having a type 00 durometer hardness specified by ASTM D 2240 of 60 or higher at 23 ° C and 30 or higher at 150 ° C.   The pressure-sensitive adhesive tape for mold release according to claim 1, wherein an application tape is laminated on the mold release surface of the fluororesin film.   The application tape is laminated to improve the ease of work when the adhesive tape for release is attached to the adherend, and after application, it is peeled to expose the release surface. The pressure-sensitive adhesive tape for release according to claim 2, which is a product.   Two release adhesive tapes are cut into 38 mm × 70 mm, and the adhesive layers are bonded together to form a test piece. The bending moment defined by JIS P 8125 of the test piece is 2.0 mN · m or more. The pressure-sensitive adhesive tape for mold release according to claim 1.   The pressure-sensitive adhesive tape for release according to claim 1, wherein a release liner is laminated on the pressure-sensitive adhesive layer.   The pressure-sensitive adhesive tape for release according to claim 1, wherein the fluororesin film has a thickness of 3 to 60 µm.   In a method of manufacturing a molded product of fiber reinforced plastic (FRP) by a molding method in which a prepreg impregnated with an uncured resin in a reinforcing fiber is laminated and heated and pressed to cure, by sticking to a press surface of a press die The pressure-sensitive adhesive tape for mold release according to claim 1, which is used for improving the release property of the molded product from the press surface.

Images