Adhesive with pressure regulating function

Abstract

An adhesive having a pressure regulation function according to the present invention is used to adhere to a resin adherend having a vapor discharge port and to seal the vapor discharge port, the adhesive having a pressure regulation function having reduced adhesive force due to the heat of the vapor discharged from the vapor discharge port and being peeled off due to the pressure of the vapor. Therefore, the steam is discharged. The adhesive can reseal the vapor discharge port after the vapor is discharged, and does not need to apply an external force to the reseal. The adhesive may contain: a pressure-sensitive adhesive; and a side-chain crystalline polymer containing, as a monomer component, a (meth) acrylate having a linear alkyl group having 12-30 carbon atoms.

Description

Technical Field

[0001] The invention relates to an adhesive with a pressure regulating function. Background Art

[0002] When a sealed container is heated, the container may expand and rupture due to the generation of water vapor accompanying the heating. In order to solve this problem, many technologies have been proposed to provide a function of releasing steam by improving the lid, adhesive tape, etc. of the container. For example, Patent Document 1 proposes a structure in which a heat shrinkable film is used so that the film shrinks when heated to release steam.

[0003] On the other hand, in the previous structure proposed in Patent Document 1, the steam outlet is still opened after the steam is discharged. Therefore, it is possible to cause burns due to leakage of contents or discharge of residual steam. In addition, foreign matter may be mixed in the interior.

[0004] In order to improve such a problem, for example, Patent Document 2 proposes a structure in which the pressure-sensitive adhesive label is peeled off by the internal pressure of steam and the rigidity of the substrate is utilized to assist resealing.

[0005] However, in the structure proposed in Patent Document 2, a human operation such as sticking is required for resealing (external force), so there is still a concern of burns during resealing due to the heat of the slightly discharged steam after heating.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2016-60531

[0009] Patent Document 2: Japanese Patent No. 6771281 Summary of the invention

[0010] Problems to be solved by the invention

[0011] An object of the present invention is to provide an adhesive having a pressure regulating function and excellent sealing properties and vapor release properties.

[0012] Means for solving problems

[0013] The adhesive with pressure regulating function of the present invention is an adhesive used to be adhered to a resin adherend having a steam exhaust port to seal the above-mentioned steam exhaust port. The adhesive with pressure regulating function has its adhesive strength reduced by the heat of the steam exhausted from the above-mentioned steam exhaust port, and is peeled off due to the pressure of the steam, thereby allowing the steam to be discharged.

[0014] Effects of the Invention

[0015] According to the present invention, there are effects of excellent sealing properties and steam release properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a cross-sectional view showing an adhesive with a pressure regulating function (adhesive tape with a pressure regulating function) and an adherend according to an embodiment of the present invention, and is a view showing a state before steam is discharged.

[0017] Figure 2 This is a cross-sectional view showing an adhesive with a pressure regulating function (adhesive tape with a pressure regulating function) and an adherend according to an embodiment of the present invention, and is a view showing a state where the pressure increases due to the generation of steam.

[0018] Figure 3 This is a cross-sectional view showing an adhesive with a pressure regulating function (adhesive tape with a pressure regulating function) and an adherend according to an embodiment of the present invention, and is a view showing a state in which steam is being discharged.

[0019] Figure 4 It is a cross-sectional view showing an adhesive with a pressure regulating function (adhesive tape with a pressure regulating function) and an adherend according to an embodiment of the present invention, and is a view showing a state after steam is exhausted.

[0020] Figure 5 It is a graph showing the water vapor pressure curve relative to temperature.

[0021] Figure 6 It is a graph showing the water vapor pressure curve and the temperature change of the adhesive force of the adhesives of Example 5 and Comparative Example 1. DETAILED DESCRIPTION

[0022] Hereinafter, an adhesive with a pressure regulating function (hereinafter sometimes simply referred to as “adhesive”) according to an embodiment of the present invention will be described in detail with reference to the drawings, taking as an example a case where it is used in the form of an adhesive tape.

[0023] like Figure 1 As shown, a pressure-regulating pressure-sensitive adhesive tape (hereinafter, sometimes simply referred to as “pressure-sensitive adhesive tape”) 1 of the present embodiment includes a film-like substrate 2 and a pressure-sensitive adhesive layer 3 laminated on at least one surface of the substrate 2 .

[0024] The adhesive layer 3 contains the adhesive 4 with a pressure regulating function of the present embodiment. The adhesive layer 3 contains the adhesive 4 as a main component. The "main component" refers to the component that is contained most by weight compared to other components. The main component can be, for example, 80% by weight or more. The content of the adhesive 4 in the adhesive layer 3 can be 80 to 100% by weight.

[0025] The adhesive 4 of this embodiment is used to be attached to a resin adherend 100 having a steam outlet 101 to seal the steam outlet 101. "Sealing the steam outlet 101" is not limited to sealing the steam outlet 101 before steam is discharged, but also includes the case where the steam outlet 101 is resealed after steam is discharged. It should be noted that the steam outlet 101 functions as a part for discharging steam. As the shape of the steam outlet 101, for example, a hole shape, a slit shape, etc. can be cited.

[0026] Examples of the resin constituting the adherend 100 include synthetic resins such as polyethylene, polyethylene terephthalate (hereinafter, sometimes referred to as “PET”), polypropylene, polyester, polystyrene, polyamide (hereinafter, sometimes referred to as “nylon”), polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, and polyvinyl chloride.

[0027] It should be noted that the adherend 100 may not be entirely made of resin. As for the adherend 100, as long as the periphery of the steam exhaust port 101 adhered by the adhesive 4 is made of resin, it is sufficient. Therefore, the adherend 100 may have a portion made of a material other than resin in the area not adhered by the adhesive 4.

[0028] Examples of the adherend 100 include containers used for packaging and the like. Figure 1 In the embodiment, a container is shown as an example of the adherend 100. When the adherend 100 is a container, as the contained content, a content that generates water vapor or the like when heated can be cited. In addition, the adherend 100 may be subjected to surface treatment such as printing.

[0029] Here, the adhesive 4 of this embodiment has a pressure regulating function. In other words, the adhesive 4 of this embodiment can exert a pressure regulating function. Moreover, the adhesive 4 has excellent sealing properties and steam release properties.

[0030] Figure 5 and Figure 6 The saturated water vapor pressure curve is shown in FIG. , and water vapor pressure is used as an example for explanation. Figure 5 The water vapor pressure curve relative to temperature is shown in FIG. 1. As can be seen from the figure, the water vapor pressure rises sharply around 60°C. Figure 6 Graphs showing water vapor pressure curves and temperature changes in adhesive strength of adhesives of Example 5 and Comparative Example 1 described later are shown in FIG. Figure 6 The adhesive 4 of the present embodiment (Example 5) shown has low adhesive strength at 60°C where the water vapor pressure rises sharply, and maintains this low adhesive strength even at 100°C. On the other hand, the adhesive strength of Comparative Example 1 decreases approximately linearly at room temperature (e.g., 23°C), 60°C, and 100°C.

[0031] This characteristic is applied to the heating process of this embodiment for explanation. Figure 2 As shown in FIG. 1 , when the adherend 100 is heated, the internal temperature of the adherend 100 rises, and the internal pressure of the adherend 100, that is, the water vapor pressure, rises. When the temperature of the adherend 100 reaches about 60° C., as shown in FIG. Figure 3 As shown, the adhesive force of the adhesive 4 decreases sharply, and the pressure applied to the steam outlet 101 causes the pressure regulating adhesive tape 1 to peel off from the surface of the adherend 100. The steam outlet 101 opens to discharge the steam inside the adherend 100 to the outside.

[0032] In this case, the adhesive force of the adhesive 4 at room temperature must be high, and the adhesive force at 60°C must be low. At room temperature, the inside and the outside need to be blocked, and sufficient adhesive force is required to seal the steam outlet 101. At 60°C, in order to prevent the damage of the adherend, the rapidly rising water vapor pressure needs to be discharged to the outside effectively and efficiently, so the adhesive force of the adhesive 4 at 60°C needs to be sufficiently reduced. The adhesive force at 60°C is preferably 2N / 25mm or less, and more preferably 1N / 25mm or less. It should be noted that the method for measuring the adhesive force is described later.

[0033] If the adhesive force at 60°C is a value greater than 2N / 25mm, there is a possibility that water vapor cannot be fully discharged or the adherend 100 may be damaged due to pressure concentration. When the adherend 100 is heated and the water vapor pressure inside becomes high near 60°C, the adhesive tape covering the steam outlet 101 is pressurized from the inside of the adherend 100 by the water vapor. Here, if the adhesive force at 60°C is a value greater than 2N / 25mm, sometimes the adhesive tape covering the steam outlet 101 is not peeled off and the adherend 100 is damaged. Alternatively, the adhesive tape covering the steam outlet 101 cannot be peeled off uniformly, and there is a high possibility that only the part with the weakest adhesive force, that is, only a part of the adhesive tape, is peeled off. In this case, the water vapor inside the adherend 100 is concentratedly discharged from the peeled part of the steam outlet 101, so the water vapor is not fully discharged or the adherend 100 is damaged due to pressure concentration.

[0034] This point can be more specifically expressed by the adhesive force reduction coefficient shown in Formula 1.

[0035] Formula 1: Adhesion reduction coefficient = "23°C adhesion" / "60°C adhesion"

[0036] The adhesive force reduction coefficient is preferably 4 or more, and more preferably 10 or more. When the adhesive force reduction coefficient is 4 or more, the adhesive force at room temperature (e.g., 23° C.) can be ensured, that is, the steam outlet 101 can be sealed, and the steam outlet 101 can be reliably opened at 60° C. When the adhesive force reduction coefficient is less than 4, the adhesive force at room temperature is too low to seal the steam outlet 101, or the adhesive force at 60° C. is too high to reliably open the steam outlet 101.

[0037] Furthermore, the change in the adhesive force of the adhesive 4 can be set in more detail based on the degree of change in the adhesive force represented by Formula 2.

[0038] Formula 2: Adhesion change ratio = "23°C adhesion / 60°C adhesion" / "60°C adhesion / 100°C adhesion ratio"

[0039] The degree of variation in adhesive force is preferably 1 or more, and more preferably 4 or more. Figure 6 The change in water vapor pressure and the change in adhesive force are shown. When the degree of adhesive force change is greater than 1, that is, when the change from 60°C to 100°C is smaller than the change from 23°C to 60°C, the adhesive force of the adhesive 4 is greatly reduced in the temperature region where the water vapor pressure rises sharply, and then the reduced adhesive force 4 can be maintained, and the steam outlet 101 opened at 60°C remains open even at 100°C.

[0040] On the other hand, when the degree of change in adhesive force is less than 1, that is, when the change from 60°C to 100°C is greater than the change from 23°C to 60°C, the adhesive force is not sufficiently reduced in the temperature region where the water vapor pressure in the adherend 100 rises sharply, and there is a possibility that the adherend 100 is damaged. Furthermore, when the temperature of the adherend 100 continues to rise, the extremely increased water vapor pressure in the adherend 100 is rapidly discharged at around 100°C, so there is a possibility that the steam discharge port 101 is damaged or the adherend 100 is damaged.

[0041] In addition, if Figure 4 As shown, the adhesive 4 of this embodiment can reseal the steam outlet 101 after the steam is discharged, and no external force is required for resealing. The adhesive 4 can reseal the steam outlet 101 without human contact. In this case, the adhesive 4 can also achieve excellent resealing properties.

[0042] It is believed that resealing can be achieved by the adhesive force in the high temperature area, that is, the temperature area above 60°C. When steam is discharged from the steam outlet 101, the steam passes through the steam outlet 101 and is continuously discharged from the adherend 100 to the outside. Even when the temperature rise stops and the temperature begins to gradually decrease, the steam is continuously discharged until the temperature is around 60°C. In the previous technology, even if the adhesive tape is in contact with the steam outlet 101, it cannot stay there, and it is difficult to reseal without external force. In the adhesive tape 1 with a pressure regulating function of the present embodiment, the adhesive force is strong in the high temperature area of ​​60°C and 100°C, the momentum of the steam discharged from the steam outlet 101 is weakened, and when the adhesive 4 contacts the periphery of the steam outlet 101, it temporarily becomes a bonded state due to its high adhesive force. Next, when the temperature is lower than 60°C and the inside of the adherend 100 is gradually depressurized, the adhesive 4 is bonded to the periphery of the steam outlet 101 with the temporary bonding portion using the adhesive force as the starting point, and the steam outlet 101 can be sealed again. The adhesive force of the adhesive 4 at 60°C is preferably 3N / 19.6mm 2 More than, more preferably 6N / 19.6mm 2 The above is mentioned. In addition, the measuring method of adhesive force is described later.

[0043] The adhesive 4 of the present embodiment has excellent sealing properties (fixing force) at room temperature (eg, 23° C.) In addition, the adhesive 4 of the present embodiment has excellent easy peelability when heated and excellent resealing properties after heating.

[0044] The adhesive 4 of this embodiment may contain a pressure-sensitive adhesive and a side-chain crystalline polymer. Such an adhesive 4 is also called a temperature-sensitive adhesive. A temperature-sensitive adhesive is an adhesive whose adhesive force changes in accordance with temperature changes. The following specifically describes the case where the adhesive 4 is a temperature-sensitive adhesive.

[0045] Pressure sensitive adhesives are polymers that have adhesive properties.

[0046] The side chain crystalline polymer contains a (meth)acrylate having a linear alkyl group having 12 to 30 carbon atoms as a monomer component. Regarding the (meth)acrylate having a linear alkyl group having 12 to 30 carbon atoms, the linear alkyl group having 12 to 30 carbon atoms functions as a side chain crystalline site in the side chain crystalline polymer. That is, the side chain crystalline polymer is a comb-shaped polymer having a linear alkyl group having 12 to 30 carbon atoms in the side chain, and the side chain is integrated into an orderly arrangement by intermolecular forces, etc., thereby crystallizing.

[0047] In addition, the side chain crystalline polymer is a polymer having a melting point. The melting point refers to the temperature at which a specific part of the polymer that was initially integrated into an orderly arrangement becomes a disordered state through a certain equilibrium process, and is a value obtained by measuring using a differential scanning calorimeter (DSC) under the measurement condition of a temperature increase rate of 10°C / min.

[0048] The side chain crystalline polymer crystallizes at a temperature lower than the above melting point, and undergoes a phase change at a temperature above the melting point to show fluidity. That is, the side chain crystalline polymer has a temperature sensitivity that reversibly causes a crystalline state and a fluid state in response to temperature changes. Thus, at a temperature lower than the melting point, the side chain crystalline polymer is in a crystalline state, so the adhesive 4 has sufficient adhesion to the resin. Therefore, when the adhesive 4 is a temperature-sensitive adhesive, it exhibits excellent sealing properties (sealing properties or fixing power) at a temperature lower than the melting point.

[0049] In addition, at a temperature above the melting point, the side chain crystalline polymer exhibits fluidity, thereby hindering the adhesiveness of the above-mentioned pressure-sensitive adhesive. As a result, the adhesive force of the adhesive 4 to the resin is reduced. That is, in the case where the adhesive 4 is a temperature-sensitive adhesive, the adhesive force to the resin is reduced at a temperature above the melting point of the side chain crystalline polymer. Therefore, the adhesive 4 exhibits excellent vapor release (easy peelability) at a temperature above the melting point.

[0050] In addition, when the adhesive 4 is a temperature-sensitive adhesive, the adhesive force at high temperature (e.g., 100° C.) is high. Therefore, the re-sealing property after the steam is released (after heating) is excellent. Furthermore, if the adhesive 4 is cooled to a temperature lower than the melting point of the side chain crystalline polymer, the side chain crystalline polymer crystallizes and the adhesive force is restored, so the re-sealing property is further excellent.

[0051] For the (meth)acrylate having a linear alkyl group with 12 to 30 carbon atoms as a monomer component constituting the side chain crystalline polymer, for example, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, eicosyl (meth)acrylate, behenyl (meth)acrylate, etc. can be cited. Only one of the exemplified (meth)acrylates can be used, or two or more can be used in combination. It should be noted that (meth)acrylate refers to acrylate or methacrylate. In addition, the number of carbon atoms in the linear alkyl group is preferably 16 to 30.

[0052] The monomer components constituting the side chain crystalline polymer may contain other monomers copolymerizable with the (meth)acrylate having a linear alkyl group having 12 to 30 carbon atoms. Examples of the other monomers include (meth)acrylate having an alkyl group having 1 to 6 carbon atoms and polar monomers.

[0053] Examples of the (meth)acrylate having an alkyl group having 1 to 6 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, etc. The exemplified (meth)acrylates may be used alone or in combination of two or more.

[0054] Examples of polar monomers include: ethylenically unsaturated monomers having a carboxyl group, such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid; ethylenically unsaturated monomers having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxyhexyl (meth)acrylate. The polar monomers exemplified may be used alone or in combination of two or more.

[0055] A preferred composition of the side chain crystalline polymer containing a (meth)acrylate having an alkyl group having 1 to 6 carbon atoms as a monomer component and containing no polar monomer as a monomer component may be 35 to 95% by weight of a (meth)acrylate having a linear alkyl group having 12 to 30 carbon atoms and 5 to 65% by weight of a (meth)acrylate having an alkyl group having 1 to 6 carbon atoms. A more preferred composition may be 35 to 80% by weight of a (meth)acrylate having a linear alkyl group having 12 to 30 carbon atoms and 20 to 65% by weight of a (meth)acrylate having an alkyl group having 1 to 6 carbon atoms.

[0056] A preferred composition of the side chain crystalline polymer containing a (meth)acrylate having an alkyl group having 1 to 6 carbon atoms and a polar monomer as monomer components may be 30 to 95% by weight of a (meth)acrylate having a linear alkyl group having 12 to 30 carbon atoms, 0 to 60% by weight of a (meth)acrylate having an alkyl group having 1 to 6 carbon atoms, and 5 to 10% by weight of the polar monomer. A more preferred composition may be 60 to 89% by weight of a (meth)acrylate having a linear alkyl group having 12 to 30 carbon atoms, 10 to 30% by weight of a (meth)acrylate having an alkyl group having 1 to 6 carbon atoms, and 1 to 10% by weight of the polar monomer.

[0057] Examples of the polymerization method of the monomer components include solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. In the case of solution polymerization, the monomer components are mixed with a solvent, a polymerization initiator, a chain transfer agent, etc. are added as needed, and the mixture is reacted at about 40 to 90° C. for about 2 to 10 hours while stirring.

[0058] The melting point of the side chain crystalline polymer is preferably 100° C. or less, more preferably 30 to 80° C., and further preferably 30 to 60° C. In this case, excellent blocking properties (fixing power) can be exerted at room temperature (e.g., 23° C.). The melting point can be adjusted, for example, by changing the composition of the monomer components constituting the side chain crystalline polymer.

[0059] The weight average molecular weight of the side chain crystalline polymer is preferably 3000 to 20000, and more preferably 5000 to 15000. In this case, when the side chain crystalline polymer exhibits fluidity, the adhesive force can be sufficiently reduced. It should be noted that the weight average molecular weight is a value obtained by measuring the measured value using gel permeation chromatography (GPC) and converting the obtained measured value into polystyrene.

[0060] The content of the side chain crystalline polymer is preferably 30 parts by weight or less, more preferably 3 to 20 parts by weight, based on 100 parts by weight of the pressure-sensitive adhesive. In this case, when the side chain crystalline polymer exhibits fluidity at a temperature above the melting point, the adhesive force of the adhesive 4 to the resin can be sufficiently reduced.

[0061] The pressure-sensitive adhesive may also be acrylic. As monomer components constituting the acrylic pressure-sensitive adhesive, for example, (meth)acrylates having an alkyl group with 1 to 12 carbon atoms may be cited. As (meth)acrylates having an alkyl group with 1 to 12 carbon atoms, for example, 2-ethylhexyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, etc. may be cited. The exemplified (meth)acrylates may be used alone or in combination of two or more.

[0062] The pressure-sensitive adhesive may contain a polar monomer as a monomer component. In addition, the pressure-sensitive adhesive may contain a (meth)acrylate having an alkyl group having 1 to 6 carbon atoms as a monomer component. Examples of the (meth)acrylate having an alkyl group having 1 to 6 carbon atoms and the polar monomer include the same (meth)acrylate and polar monomer as exemplified in the case of the side chain crystalline polymer.

[0063] As a specific composition of a pressure-sensitive adhesive, the following composition A, B etc. are mentioned.

[0064] Composition A: Contains, as monomer components, a (meth)acrylate having an alkyl group having 1 to 12 carbon atoms and a polar monomer.

[0065] Composition B: Contains, as monomer components, a (meth)acrylate having an alkyl group having 1 to 12 carbon atoms, a (meth)acrylate having an alkyl group having 1 to 6 carbon atoms, and a polar monomer.

[0066] In composition A, the (meth)acrylate having an alkyl group with 1 to 12 carbon atoms may be 90 to 99% by weight, and the polar monomer may be 1 to 10% by weight. In composition B, the (meth)acrylate having an alkyl group with 1 to 12 carbon atoms may be 40 to 65% by weight, the (meth)acrylate having an alkyl group with 1 to 6 carbon atoms may be 30 to 50% by weight, and the polar monomer may be 5 to 10% by weight.

[0067] Examples of the polymerization method of the monomer components include solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. In the case of solution polymerization, the monomer components are mixed with a solvent, a polymerization initiator, a chain transfer agent, etc. are added as needed, and the mixture is reacted at about 40 to 90° C. for about 2 to 10 hours while stirring.

[0068] The weight average molecular weight of the pressure-sensitive adhesive as the polymer of the monomer component is preferably 200,000 to 600,000, more preferably 300,000 to 500,000. The weight average molecular weight is a value obtained by measuring the measured value by gel permeation chromatography (GPC) and converting the obtained measured value into polystyrene.

[0069] When the 180° peel strength of the adhesive 4 to the polyethylene terephthalate film at 100° C. is low, the vapor release property tends to be improved. On the other hand, when the adhesive force of the adhesive 4 at 100° C. is high, the resealing property tends to be improved.

[0070] The 180° peel strength of the adhesive 4 to the polyethylene terephthalate film at 100°C is preferably 0.3 N / 25 mm or less, more preferably 0.2 N / 25 mm or less. In addition, the adhesive force of the adhesive 4 at 100°C is preferably 2.0 N / 19.6 mm 2 More than, more preferably 3.0N / 19.6mm 2 In these cases, stable vapor release properties and re-sealability can be exhibited for the resin adherend 100 widely used in packaging applications.

[0071] The 180° peel strength is a value measured in accordance with JIS Z 0237. The adhesive force is a probe tack value measured in accordance with ASTM D 2979 except that the contact load was changed to 300 gf.

[0072] The adhesive 4 may further contain a crosslinking agent. Examples of the crosslinking agent include aziridine compounds, epoxy compounds, metal chelates, isocyanate compounds, and the like. As crosslinking conditions, the heating temperature is about 90 to 120° C., and the heating time is about 1 minute to 20 minutes. The content of the crosslinking agent is preferably 0.1 to 10 parts by weight relative to 100 parts by weight of the pressure-sensitive adhesive.

[0073] As described above, the pressure-sensitive adhesive tape 1 of the present embodiment includes the film-shaped substrate 2. The concept of the film-shaped is not limited to the film-shaped, and includes the film-shaped or sheet-shaped as long as the effects of the present embodiment are not impaired.

[0074] Examples of the constituent material of the substrate 2 include synthetic resins such as polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, and polyvinyl chloride.

[0075] The structure of the substrate 2 may be either a single-layer structure or a multilayer structure. In order to improve the adhesion to the adhesive layer 3, the substrate 2 may be subjected to a surface treatment. Examples of the surface treatment include corona discharge treatment, plasma treatment, sandblasting, chemical etching, and primer treatment.

[0076] The thickness of the substrate 2 is preferably 25 to 188 μm, more preferably 25 to 125 μm. When the thickness of the substrate 2 is 25 to 60 μm, the vapor release property tends to be improved. When the thickness of the substrate 2 is 38 to 125 μm, the resealing property tends to be improved.

[0077] In order to laminate the adhesive layer 3 on at least one side of the substrate 2, for example, a solvent may be added to the adhesive 4 to prepare a coating solution, and the obtained coating solution may be applied to one side or both sides of the substrate 2 using a coater or the like and dried. Examples of the coater include a knife coater, a roll coater, a calender coater, a comma coater, a gravure coater, and a rod coater.

[0078] The thickness of the adhesive layer 3 is preferably 5 to 100 μm, more preferably 5 to 50 μm.

[0079] When the adhesive layers are laminated on both sides of the substrate 2, the thickness, composition, etc. of the adhesive layer 3 on one side and the adhesive layer on the other side may be the same or different. In addition, as long as the adhesive layer 3 on one side includes the adhesive 4 with the pressure regulating function, the adhesive layer on the other side is not particularly limited.

[0080] A release film may be laminated on the surface of the adhesive tape 1. Examples of the release film include a release film obtained by coating a release agent such as silicone on the surface of a film made of polyethylene terephthalate or the like. The thickness of the release film is preferably 5 to 500 μm, more preferably 25 to 250 μm. The release film is peeled off when the adhesive tape 1 is used.

[0081] It should be noted that the use of the pressure regulating adhesive is not limited to the form of an adhesive tape. The adhesive may be used directly or in the form of an adhesive sheet as described below.

[0082] The pressure-regulating adhesive sheet (hereinafter sometimes referred to as "adhesive sheet") of this embodiment includes the pressure-regulating adhesive and is a sheet without a substrate. The thickness of the adhesive sheet is preferably 5 to 100 μm, more preferably 5 to 50 μm.

[0083] The adhesive sheet contains an adhesive having a pressure regulating function as a main component. The content of the adhesive in the adhesive sheet may be 80 to 100% by weight.

[0084] A release film may be laminated on the surface of the pressure-sensitive adhesive sheet. Examples of the release film include the same release films as those exemplified in the pressure-sensitive adhesive tape 1. The release film is peeled off when the pressure-sensitive adhesive sheet is used.

[0085] Hereinafter, the present invention will be described in detail with reference to synthesis examples and examples, but the present invention is not limited to the following synthesis examples and examples.

[0086] (Synthesis Examples A, B, C: Pressure-Sensitive Adhesive)

[0087] First, the monomers shown in Table 1 were added to a reaction vessel in the proportions shown in Table 1 to obtain a monomer mixture. The monomers shown in Table 1 are as follows.

[0088] EHA: 2-Ethylhexyl Acrylate

[0089] AA: Acrylic acid

[0090] C1A: Methyl acrylate

[0091] HBA: 4-Hydroxybutyl Acrylate

[0092] Next, the solvents shown in Table 1 were added to the reaction container so that the solid content concentration became the ratio shown in Table 1, thereby obtaining a mixed liquid. The solvents shown in Table 1 are as follows.

[0093] EtAc: ethyl acetate

[0094] tol: toluene

[0095] hep: heptane

[0096] The obtained mixed solution was degassed with nitrogen. The degassing time was set to be 30 minutes or more. Then, the mixed solution was heated to 55° C., and 0.3 parts by weight (solid content conversion) of peroxide "PERBUTYL ND" manufactured by NOF Corporation was added to 100 parts by weight of the monomer mixture, and the mixture was reacted for 4 hours.

[0097] Then, the mixed solution was heated to 80° C., and 0.5 parts by weight (in terms of solid content) of peroxide “PERHEXYL PV” manufactured by NOF Corporation was added to 100 parts by weight of the monomer mixture, and the mixture was reacted for 2 hours to obtain a pressure-sensitive adhesive.

[0098] (Synthesis Examples D, E, F, G: Side Chain Crystalline Polymers)

[0099] First, the monomers shown in Table 1 were added to a reaction vessel in the proportions shown in Table 1 to obtain a monomer mixture. The monomers shown in Table 1 are as follows.

[0100] C18A: Stearyl acrylate

[0101] C1A: Methyl acrylate

[0102] C22A: Behenyl acrylate

[0103] AA: Acrylic acid

[0104] Next, 5 parts by weight (in terms of solid content) of dodecyl mercaptan as a chain transfer agent was added to 100 parts by weight of the monomer mixture, and the solvents shown in Table 1 were added to the reaction container so that the solid content concentration became the ratio shown in Table 1 to obtain a mixed solution. The obtained mixed solution was then degassed with nitrogen. The degassing time was set to 30 minutes or more.

[0105] The mixed solution was then heated to 70°C, and 0.5 parts by weight (solid content conversion) of peroxide "PERHEXYL PV" manufactured by NOF Corporation was added to 100 parts by weight of the monomer mixture, and the mixture was reacted for 1 hour. The mixed solution was then heated to 80°C and reacted for 4 hours to obtain a side chain crystalline polymer.

[0106] The weight average molecular weight of the obtained pressure-sensitive adhesive is shown in Table 1. In addition, the weight average molecular weight and melting point of the obtained side chain crystalline polymer are shown in Table 1. The weight average molecular weight is a value obtained by converting the measured value obtained by GPC measurement into polystyrene. The melting point is a value obtained by measuring using DSC under the measurement condition of a temperature increase rate of 10°C / min.

[0107] Table 1

[0108]

[0109] (Adhesion to PET)

[0110] [Examples 1 to 12]

[0111] <Manufacturing of adhesive tape>

[0112] First, a coating solution was obtained by adding the crosslinking agent shown in Table 2 and the side chain crystalline polymer obtained in Synthesis Example to the pressure-sensitive adhesive obtained in Synthesis Example in the combination and addition amount shown in Table 2. It should be noted that the addition amount shown in Table 2 is a value calculated in terms of solid content relative to 100 parts by weight of the pressure-sensitive adhesive.

[0113] The cross-linking agents shown in Table 2 are as follows.

[0114] Aziridine series: Aziridine compound "Chemitite PZ-33" manufactured by Nippon Shokubai Co., Ltd.

[0115] Epoxy: Epoxy compound "TETRAD-X" manufactured by Mitsubishi Gas Chemical Co., Ltd.

[0116] Aluminum chelate system: Aluminum triacetylacetonate manufactured by Kawaken Fine Chemicals Co., Ltd. as a metal chelate

[0117] Isocyanate: Isocyanate compound "CORONATE L-45E" manufactured by Nippon Polyurethane Industries

[0118] Next, the obtained coating solution was applied to one side of the substrate, and a crosslinking reaction was carried out at 110° C. for 3 minutes to obtain an adhesive tape having an adhesive layer with a thickness of 30 μm laminated on one side of the substrate. It should be noted that the substrate used was a PET film having a thickness shown in Table 2 and subjected to corona treatment on both sides.

[0119] A release film was laminated on the surface of the obtained pressure-sensitive adhesive tape. The release film was laminated at room temperature (23° C.). A PET film with a thickness of 38 μm and a silicone-coated surface was used as the release film.

[0120] [Comparative Examples 1-2]

[0121] A pressure-sensitive adhesive tape was obtained in the same manner as in Examples 1 to 12 except that a crosslinking agent shown in Table 2 was added to the pressure-sensitive adhesive obtained in the synthesis example in the combination and amount shown in Table 2 to obtain a coating solution. Then, each evaluation was performed under the same conditions as in Examples 1 to 12 except that this pressure-sensitive adhesive tape was used.

[0122] <Evaluation>

[0123] The adhesive force to the PET film, the room temperature sealing property, and the steam release property of the obtained adhesive tape were evaluated. The evaluation methods are shown below, and the results are shown in Table 2.

[0124] (Adhesion)

[0125] The 180° peel strength of the PET film at 23°C, 60°C and 100°C was measured according to JIS Z0237. Specifically, the adhesive tape was attached to the PET film as the adherend under the following conditions, and then the adhesive tape was peeled off from the PET film as the adherend at a speed of 300 mm / min using a dynamometer (n=3). The PET film used as the adherend was a film-shaped PET film with a thickness of 0.025 mm and an untreated surface. It should be noted that (1) in the adhesive strength column of Table 2 represents the above-mentioned adhesive strength reduction coefficient, and (1) / (2) represents the above-mentioned adhesive strength change degree.

[0126] [23℃]

[0127] The pressure-sensitive adhesive tape was attached to a PET film as an adherend at an ambient temperature of 23° C., and then left to stand at the ambient temperature for 20 minutes and then peeled at 180°.

[0128] [60℃]

[0129] The pressure-sensitive adhesive tape was attached to a PET film as an adherend at an ambient temperature of 23° C. and allowed to stand at the ambient temperature for 20 minutes. The ambient temperature was then raised to 60° C. and allowed to stand at the ambient temperature for 5 minutes before being peeled off at 180°.

[0130] [100℃]

[0131] The pressure-sensitive adhesive tape was attached to a PET film as an adherend at an ambient temperature of 23° C. and allowed to stand at the ambient temperature for 20 minutes. The ambient temperature was then raised to 100° C. and allowed to stand at the ambient temperature for 5 minutes before being peeled off at 180°.

[0132] (Normal temperature sealing)

[0133] The room-temperature sealing property was evaluated from the measurement results of the adhesive strength at 23° C. The evaluation criteria were set as follows.

[0134] ◎:7.0N / 25mm or more

[0135] 0: 5.0N / 25mm or more and less than 7.0N / 25mm

[0136] ×: less than 5.0N / 25mm

[0137] (Vapor emission)

[0138] First, a test container was prepared. Specifically, a semicircular slit with a diameter of 10 mm was set in the center of a PET film with a size of 110 mm × 110 mm and a heat seal layer on one side. An adhesive tape processed into a shape of 30 mm × 30 mm was attached to the slit as the center to obtain a cover material. 100 ml of water was added to a polypropylene cup container with a diameter of 100 mm and a flange of 5 mm width, and the cover material obtained above was pressed onto it by heat sealing to prepare a test container.

[0139] The test container was heated in a microwave oven at 500 W for 90 seconds, and the steam release was evaluated by visually checking whether the heat-sealed portion was not broken and steam was discharged from the slit portion in the center (n=5). The evaluation criteria were set as follows.

[0140] ◎: Steam was discharged in all 5 times

[0141] 0: Steam was released 3-4 times out of 5 times

[0142] ×: Steam was released less than 2 times out of 5 times

[0143] Table 2

[0144]

[0145] As can be seen from Table 2, Examples 1 to 12 were excellent in easy peelability during heating. Examples 1 to 12 were found to be excellent in room temperature sealing properties to PET films and steam release properties.

[0146] (Adhesion to nylon)

[0147] [Examples 13 to 18]

[0148] <Manufacturing of adhesive tape>

[0149] The pressure-sensitive adhesive obtained in the synthesis example was added with the cross-linking agent shown in Table 3 and the side chain crystalline polymer obtained in the synthesis example in the combination and addition amount shown in Table 3 to obtain a coating liquid. The adhesive tape was obtained in the same manner as in Examples 1 to 12. It should be noted that the addition amount shown in Table 3 is a value calculated in terms of solid content relative to 100 parts by weight of the pressure-sensitive adhesive. The cross-linking agent shown in Table 3 is the same as the cross-linking agent shown in Table 2. On the surface of the obtained adhesive tape, a release film was laminated in the same manner as in Examples 1 to 12.

[0150] [Comparative Examples 3-4]

[0151] A pressure-sensitive adhesive tape was obtained in the same manner as in Examples 13 to 18 except that a crosslinking agent shown in Table 3 was added to the pressure-sensitive adhesive obtained in the synthesis example in the combination and amount shown in Table 3 to obtain a coating solution. Then, each evaluation was performed under the same conditions as in Examples 13 to 18 except that this pressure-sensitive adhesive tape was used.

[0152] <Evaluation>

[0153] The adhesive force to nylon, room temperature sealing property, and steam release property of the obtained adhesive tape were evaluated. The evaluation methods are shown below, and the results are shown in Table 3.

[0154] (Adhesion)

[0155] The 180° peel strength to the nylon film was measured at 23° C., 60° C. and 100° C. under the same conditions as the adhesive strength to PET, except that a nylon film was used as the adherend instead of the PET film. The nylon film used was a 0.015 mm thick film without surface treatment.

[0156] (Normal temperature sealing)

[0157] Evaluation was performed under the same conditions as for the room-temperature sealability in the adhesive strength to PET.

[0158] (Vapor emission)

[0159] A test container was prepared in the same manner as for the vapor release property in the adhesion to PET, except that a nylon film was used instead of the PET film to obtain a lid material. Then, the vapor release property in the adhesion to PET was evaluated under the same conditions as for the vapor release property in the adhesion to PET, except that the test container was used.

[0160] Table 3

[0161]

[0162] As can be seen from Table 3, Examples 13 to 18 were excellent in easy peelability during heating. Examples 13 to 18 were found to be excellent in room temperature sealing properties to nylon films and steam release properties.

[0163] (Adhesion)

[0164] [Examples 19 to 30]

[0165] <Manufacturing of adhesive tape>

[0166] The pressure-sensitive adhesive obtained in the synthesis example was added with the cross-linking agent shown in Table 4 and the side chain crystalline polymer obtained in the synthesis example in the combination and addition amount shown in Table 4 to obtain a coating liquid. The adhesive tape was obtained in the same manner as in Examples 1 to 12. It should be noted that the addition amount shown in Table 4 is a value calculated in terms of solid content relative to 100 parts by weight of the pressure-sensitive adhesive. The cross-linking agent shown in Table 4 is the same as the cross-linking agent shown in Table 2. On the surface of the obtained adhesive tape, a release film was laminated in the same manner as in Examples 1 to 12.

[0167] The adhesive force and resealing property of the obtained pressure-sensitive adhesive tape were evaluated. The evaluation methods are shown below, and the results are shown in Table 4.

[0168] (Adhesion)

[0169] The probe tack values ​​at 23° C., 60° C., and 100° C. were measured in accordance with ASTM D 2979 except that the contact load was changed to 300 gf.

[0170] (Resealability)

[0171] After the evaluation of the "vapor release property" in the above-mentioned adhesive force to PET, it was evaluated whether or not resealing was performed without applying an external force. The evaluation criteria were set as follows.

[0172] ◎: All 5 times were resealed

[0173] 0: Resealed 3-4 times out of 5 times

[0174] ×: Resealed less than 2 times out of 5 times

[0175] [Comparative Example 5]

[0176] A pressure-sensitive adhesive tape was obtained in the same manner as in Examples 19 to 30 except that a crosslinking agent shown in Table 4 and a foaming agent shown below were added to the pressure-sensitive adhesive obtained in the synthesis example in the combination and amount shown in Table 4 to obtain a coating solution. Then, each evaluation was performed under the same conditions as in Examples 19 to 30 except that this pressure-sensitive adhesive tape was used. The results are shown in Table 4.

[0177] Blowing agent: Thermally expandable microcapsules "551DU40" manufactured by EXPANCEL with an average particle size of 10 to 16 μm and a foaming temperature of 90°C or higher

[0178] Table 4

[0179]

[0180] As can be seen from Table 4, Examples 19 to 30 can achieve re-sealing properties (re-closing properties) after heating without applying an external force. It can be seen that Examples 19 to 30 are excellent in re-sealing properties.

[0181] Description of Reference Numerals

[0182] 1…Adhesive tape with pressure adjustment function

[0183] 2…Base material

[0184] 3…Adhesive layer

[0185] 4…Adhesive with pressure regulation function

[0186] 100…Adhesive

[0187] 101…Steam outlet

Claims

1. An adhesive having a pressure regulating function, which is used to adhere to a resin adherend having a steam exhaust port and seal the steam exhaust port, The adhesive with a pressure regulating function has its adhesive strength reduced by the heat of the steam exhausted from the steam exhaust port, and is peeled off by the pressure of the steam, thereby exhausting the steam. 2 . The adhesive with pressure regulating function according to claim 1 , which can reseal the steam outlet after the steam is discharged, and the reseal does not require external force.

3. The adhesive with pressure regulating function according to claim 1 or 2, wherein: The adhesive comprises: Pressure sensitive adhesives; and The side chain crystalline polymer contains, as a monomer component, a (meth)acrylate having a linear alkyl group having 12 to 30 carbon atoms. 4 . The pressure-regulating adhesive according to claim 3 , wherein the adhesive force to the resin decreases at a temperature equal to or higher than the melting point of the side chain crystalline polymer. 5 . An adhesive sheet with a pressure regulating function, comprising the adhesive with a pressure regulating function according to claim 1 or 2 .

6. An adhesive tape with pressure regulating function, comprising: a film-like substrate; and The adhesive layer is laminated on at least one surface of the substrate and contains the adhesive with pressure regulating function according to claim 1 or 2.

Images