WO2021117673A1 - High-frequency dielectric heating adhesive sheet, method for using high-frequency dielectric heating adhesive sheet, and bonding method using high-frequency dielectric heating adhesive sheet - Google Patents

Abstract

A high-frequency dielectric heating adhesive sheet (10) which contains an ethylene-vinyl acetate copolymer and a dielectric filler that generates heat at high frequencies , while having a first surface (11) and a second surface (12) that is on the reverse side of the first surface (11) that has a surface free energy of 40 mJ/m² or more. This high-frequency dielectric heating adhesive sheet (10) is used for the purpose of bonding a first adherend, which contains one resin that is selected from the group consisting of acrylic resins, polyurethane resins and polyester resins, to the first surface (11) and bonding a second adherend, which is formed from a polyolefin resin, to the second surface (12).

Description

How to use high frequency dielectric heating adhesive sheet, high frequency dielectric heating adhesive sheet and bonding method using high frequency dielectric heating adhesive sheet

The present invention relates to a high-frequency dielectric heating adhesive sheet, a method of using a high-frequency dielectric heating adhesive sheet, and a bonding method using a high-frequency dielectric heating adhesive sheet.

In recent years, as a method of adhering adherends that are generally difficult to adhere to each other, for example, an adhesive made by blending a heat-generating material in a predetermined resin is interposed between the adherends and subjected to dielectric heating treatment. , Induction heat treatment, ultrasonic welding treatment, laser welding treatment and the like have been proposed.

For example, Patent Document 1 and Patent Document 2 describe a dielectric heating adhesive film used for a dielectric heating treatment. The dielectric heating adhesive films described in Patent Document 1 and Patent Document 2 contain an olefin-vinyl acetate copolymer and a dielectric filler.

International Publication No. 2018/147351 International Publication No. 2018/147352

When it is attempted to bond adherends of different materials (first adherend and second adherend) using the dielectric heating adhesive films described in Patent Document 1 and Patent Document 2, sufficient adhesive strength is obtained. May not be obtained. In particular, when the material of the surface of the adherend in contact with the dielectric heating adhesive film is acrylic resin or the like, it is difficult to obtain sufficient adhesive strength.
Further, although an adherend made of vinyl chloride (PVC) has been used, a polyolefin resin such as polyethylene is being studied as an alternative material to PVC from the viewpoint of environmental problems and the like. When an adherend made of a polyolefin resin and an adherend made of a different material are adhered to each other, the conventional adhesive sheets cannot firmly adhere both adherends made of different materials to each other.

An object of the present invention is to provide a first adherend that is adhered to the first surface of a high-frequency dielectric heating adhesive sheet and a second adherend that is adhered to a second surface of a high-frequency dielectric heating adhesive sheet. It is an object of the present invention to provide a high-frequency dielectric heating adhesive sheet capable of firmly adhering a first adherend and a second adherend even if they are made of different materials.
Another object of the present invention is to provide a method of using the high-frequency dielectric heating adhesive sheet and a method of bonding using the high-frequency dielectric heating adhesive sheet.

According to one aspect of the present invention, it is a high-frequency dielectric heating adhesive sheet.
It contains an ethylene-vinyl acetate copolymer and a dielectric filler that generates heat at high frequencies.
It has a first surface and a second surface opposite to the first surface.
The surface free energy of the first surface is 40 mJ / m ² or more.
A first adherend containing any resin selected from the group consisting of an acrylic resin, a polyurethane resin, and a polyester resin is adhered to the first surface, and the second surface is made of a polyolefin resin. Used to bond the second adherend,
A high frequency dielectric heating adhesive sheet is provided.

In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the vinyl acetate copolymerization ratio of the ethylene-vinyl acetate copolymer is preferably 3% by mass or more and 40% by mass or less.

In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, it is preferable that the dielectric filler generates heat when a high-frequency voltage of 3 MHz or more and 300 MHz or less is applied.

In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the dielectric filler is preferably contained in the high-frequency dielectric heating adhesive sheet in an amount of 3% by volume or more and 50% by volume or less.

In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the average particle size of the dielectric filler is preferably 1 μm or more and 30 μm or less.

In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the dielectric filler is preferably at least one selected from the group consisting of zinc oxide, anatase-type titanium oxide, barium titanate, and silicon carbide.

In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the thickness of the high-frequency dielectric heating adhesive sheet is preferably 10 μm or more.

In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the average particle size _DF of the dielectric filler and the thickness T of the high-frequency dielectric heating adhesive sheet satisfy the relationship of _{1 ≦ T / DF ≦ 2500.} Is preferable.

In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the tensile elongation at break of the high-frequency dielectric heating adhesive sheet is preferably 1% or more.

In the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the polyolefin-based resin in the second adherend is preferably polyethylene or an ethylene-vinyl acetate copolymer.

According to one aspect of the present invention, the method of using the high-frequency dielectric heating adhesive sheet according to the above-mentioned aspect of the present invention.
The high-frequency dielectric heating adhesive sheet is sandwiched between the first adherend and the second adherend, and a high-frequency voltage of 3 MHz or more and 300 MHz or less is applied to the first adherend. When a bonded body in which the first adherend and the second adherend are adhered to each other is prepared and the joined body is subjected to a tensile shear test, at least the first adherend and the second adherend are formed. Provided is a method of using a high frequency dielectric heating adhesive sheet in which one is broken or the tensile shear force is 0.2 MPa or more.

According to one aspect of the present invention, the bonding method uses a high-frequency dielectric heating adhesive sheet, and the high-frequency dielectric heating adhesive sheet contains an ethylene-vinyl acetate copolymer and a dielectric filler that reacts at a high frequency. And
The high frequency dielectric heating adhesive sheet has a first surface and a second surface opposite to the first surface.
The surface free energy of the first surface is 40 mJ / m ² or more.
A first adherend containing any resin selected from the group consisting of an acrylic resin, a polyurethane resin, and a polyester resin is brought into contact with the first surface, and a second adherend made of a polyolefin resin is brought into contact with the first surface. A step of bringing the body into contact with the second surface and sandwiching the high-frequency dielectric heating adhesive sheet between the first adherend and the second adherend.
A step of applying a high-frequency voltage of 3 MHz or more and 300 MHz or less to the high-frequency dielectric heating adhesive sheet to bond the first adherend and the second adherend with the high-frequency dielectric heating adhesive sheet. Adhesion methods using high frequency dielectric heating adhesive sheets are provided.

In the bonding method using the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the first surface is modified ^{to adjust the surface free energy of the first surface to 40 mJ / m 2} or more. It is preferable to include further steps.

In the bonding method using the high-frequency dielectric heating adhesive sheet according to one aspect of the present invention, the modification treatment is preferably at least one of corona treatment and plasma treatment.

According to one aspect of the present invention, a first adherend adhered to the first surface of the high frequency dielectric heating adhesive sheet and a second adherend adhered to the second surface of the high frequency dielectric heating adhesive sheet. It is possible to provide a high-frequency dielectric heating adhesive sheet capable of firmly adhering a first adherend and a second adherend even if the body is made of a different material.
According to one aspect of the present invention, it is possible to provide a method of using the high-frequency dielectric heating adhesive sheet and a bonding method using the high-frequency dielectric heating adhesive sheet.

It is the schematic of the high-frequency dielectric heating adhesive sheet which concerns on one Embodiment. It is a schematic diagram explaining the high frequency dielectric heating treatment using the high frequency dielectric heating adhesive sheet and the dielectric heating apparatus which concerns on one Embodiment.

[High-frequency dielectric heating adhesive sheet]
The high-frequency dielectric heating adhesive sheet according to the present embodiment contains an ethylene-vinyl acetate copolymer and a dielectric filler that generates heat at high frequencies.
The high-frequency dielectric heating adhesive sheet according to the present embodiment has a first surface and a second surface opposite to the first surface.
The surface free energy of the first surface is 40 mJ / m ² or more.
In the high-frequency dielectric heating adhesive sheet according to the present embodiment, a first adherend containing any resin selected from the group consisting of acrylic resin, polyurethane resin and polyester resin is adhered to the first surface. , Used to adhere a second adherend made of a polyolefin resin to the second surface.
The high-frequency dielectric heating adhesive sheet according to the present embodiment can bond the first adherend and the second adherend, which are different types of materials from each other.
The details of the high-frequency dielectric heating adhesive sheet according to the present embodiment will be described below.

FIG. 1 shows a schematic view of an example of a high-frequency dielectric heating adhesive sheet according to the present embodiment. The high frequency dielectric heating adhesive sheet 10 shown in FIG. 1 has a first surface 11 and a second surface 12 opposite to the first surface 11.

(First surface)
The first surface is a surface to which a first adherend containing any resin selected from the group consisting of an acrylic resin, a polyurethane resin, and a polyester resin is adhered.
In the high-frequency dielectric heating adhesive sheet according to the present embodiment that the surface free energy of the first surface, and at 40 mJ / ^{m 2} or more, and more preferably 41 mJ / ^{m 2} or more, 43 mJ / ^{m 2} or more Is even more preferable.
If the surface free energy of the first surface ^{is less than 40 mJ / m 2,} it is difficult to firmly adhere to the first adherend.
The higher the upper limit of the surface free energy of the first surface, the more preferable. For example, the surface free energy of the first surface is preferably less than ^{70 mJ / m 2.}
When the surface free energy of the first surface is 40 mJ / m ² or more, the first surface contains any resin selected from the group consisting of acrylic resin, polyurethane resin and polyester resin. The first adherend can be firmly adhered.

Examples of the method for adjusting the surface free energy of the surface of the high-frequency dielectric heating adhesive sheet to 40 mJ / m ² or more include a method of modifying the surface of the high-frequency dielectric heating adhesive sheet or a primer coating method. The method of application is more preferable. Examples of the reforming treatment include corona treatment, plasma treatment, flame treatment, ultraviolet treatment (excimer treatment), electron beam treatment, and radiation treatment. The reforming treatment is preferably at least one of corona treatment and plasma treatment.

Further, the high-frequency dielectric heating adhesive sheet may be a multilayer sheet in which a plurality of layers are laminated. In the case of a multilayer sheet, the surface in contact with the first adherend is the first surface. For example, when a multilayer sheet is composed of a first sheet layer and a second sheet layer, surface free energy can be used as a material constituting at least one of the first sheet layer and the second sheet layer. There also by selecting a material for the 40 mJ / m ² or more, it is possible to surface free energy to obtain a laminated high-frequency dielectric heating adhesive sheet having a first surface is 40 mJ / m ² or more. The high-frequency dielectric heating adhesive sheet is preferably a single-layer sheet from the viewpoint of making the sheet structure simpler and easier to manufacture and preventing delamination.

-Measurement of surface free energy In this specification, surface free energy is measured by the following method.
The contact angle (measurement temperature: 25 ° C.) of various droplets is measured, and the contact angle is determined by the Kitazaki-Hata method based on the value of the contact angle. Diiodomethane, 1-bromonaphthalene, and distilled water are used as droplets, and using DM-701 manufactured by Kyowa Interface Science Co., Ltd., the contact angle (measurement temperature) is based on JIS R 3257: 1999 by the intravenous drop method. : 25 ° C), and the surface free energy is calculated by the Kitazaki-Hata method based on the value of the contact angle. The unit of surface free energy is mJ / m ² .

(Second surface)
The second surface is the surface opposite to the first surface.
The second surface is the surface to which the second adherend made of the polyolefin resin is adhered.

In the high-frequency dielectric heating adhesive sheet according to the present embodiment, the surface free energy of the second surface is not particularly limited as long as the surface free energy of the first surface satisfies the above range.
In one embodiment, the surface free energy of the second surface ^{may be 40 mJ / m 2} or more. The surface free energy of the second surface can be adjusted ^{to 40 mJ / m 2} or more in the same manner as the first surface, for example.

(Thickness of high-frequency dielectric heating adhesive sheet)
The thickness of the high-frequency dielectric heating adhesive sheet is preferably 10 μm or more, more preferably 30 μm or more, and further preferably 50 μm or more.
If the thickness of the high-frequency dielectric heating adhesive sheet is 10 μm or more, the high-frequency dielectric heating adhesive sheet follows the unevenness of the adherend when adhering the first adherend and the second adherend. It is easy to develop adhesive strength.
The upper limit of the thickness of the high-frequency dielectric heating adhesive sheet is not particularly limited. As the thickness of the high-frequency dielectric heating adhesive sheet increases, the weight of the entire joint obtained by bonding the first adherend and the second adherend also increases. Therefore, the high-frequency dielectric heating adhesive sheet is actually used. It is preferable that the thickness is within a range where there is no problem in use. Considering the practicality and moldability of the high-frequency dielectric heating adhesive sheet, the thickness of the high-frequency dielectric heating adhesive sheet is preferably 2000 μm or less, more preferably 1000 μm or less, and further preferably 600 μm or less. ..

(Tension breaking elongation of high-frequency dielectric heating adhesive sheet)
The tensile elongation at break of the high-frequency dielectric heating adhesive sheet is preferably 1% or more.
The tensile elongation at break of the high-frequency dielectric heating adhesive sheet is preferably 2000% or less.
When the tensile elongation at break of the high-frequency dielectric heating adhesive sheet is 1% or more, the sheet is less likely to become brittle and stable bonding strength can be easily obtained.
The higher the tensile elongation at break of the high-frequency dielectric heating adhesive sheet, the better, but if it is 2000% or less, the toughness is suppressed from becoming too high, and it is unlikely that problems will occur when processing slits or the like.
The tensile elongation at break of the high-frequency dielectric heating adhesive sheet is preferably 10% or more, more preferably 30% or more, further preferably 100% or more, and even more preferably 300% or more. preferable. When the tensile elongation at break of the high-frequency dielectric heating adhesive sheet is 300% or more, the stability of the sheet strength can be easily obtained.
The tensile elongation at break of the high-frequency dielectric heating adhesive sheet is preferably 2000% or less, more preferably 1500% or less, and even more preferably 1000% or less.
The tensile elongation at break can be measured by the method described in Examples described later.

(Dielectric characteristics of high-frequency dielectric heating adhesive sheet (tan δ / ε'))
The dielectric loss tangent (tan δ) and the dielectric constant (ε') as the dielectric properties of the high-frequency dielectric heating adhesive sheet can be measured according to JIS C 2138: 2007, but they are simple and simple according to the impedance material method. It can be measured accurately.
The dielectric property (tan δ / ε') of the high-frequency dielectric heating adhesive sheet is preferably 0.005 or more, more preferably 0.008 or more, and further preferably 0.01 or more. Further, the dielectric property (tan δ / ε') of the high-frequency dielectric heating adhesive sheet is preferably 0.08 or less, and more preferably 0.05 or less. The dielectric property (tan δ / ε') is a value obtained by dividing the dielectric loss tangent (tan δ) measured using an impedance material device or the like by the dielectric constant (ε') measured using an impedance material device or the like.
If the dielectric property of the high-frequency dielectric heating adhesive sheet is 0.005 or more, there is a problem that it becomes difficult to firmly bond the adherends to each other without generating a predetermined heat when the dielectric heat treatment is performed. Can be prevented.
If the dielectric property of the high-frequency dielectric heating adhesive sheet is 0.08 or less, damage to the adherend is unlikely to occur.
The details of the method for measuring the dielectric properties of the high-frequency dielectric heating adhesive sheet are as follows. A high-frequency dielectric heating adhesive sheet cut to a predetermined size was subjected to a dielectric constant (ε') and a dielectric loss tangent (tan δ) under the condition of a frequency of 40.68 MHz at 23 ° C. using an RF impedance material analyzer E4991A (manufactured by Agent). ) Are measured, and the value of the dielectric property (tan δ / ε') is calculated.

(Ethylene-vinyl acetate copolymer)
The high-frequency dielectric heating adhesive sheet according to this embodiment contains a thermoplastic resin. The high-frequency dielectric heating adhesive sheet according to the present embodiment contains an ethylene-vinyl acetate copolymer as a thermoplastic resin. From the viewpoint of firmly adhering the first adherend and the second adherend, the thermoplastic resin preferably contains an ethylene-vinyl acetate copolymer as a main component. When the ethylene-vinyl acetate copolymer is the main component, it is easy to obtain the adhesive strength with the adherend made of ethylene or the ethylene copolymer.
The thermoplastic resin contained in the high-frequency dielectric heating adhesive sheet is preferably an ethylene-vinyl acetate copolymer, and the content of the ethylene-vinyl acetate copolymer in the thermoplastic resin is 70% by mass or more. It is more preferably 80% by mass or more, further preferably 90% by mass or more, and even more preferably 95% by mass or more. Further, as one aspect of the high-frequency dielectric heating adhesive sheet according to the present embodiment, for example, it is also preferable that the thermoplastic resin is substantially composed of only an ethylene-vinyl acetate copolymer. In addition, substantially means that the thermoplastic resin is only from the ethylene-vinyl acetate copolymer, except for a small amount of impurities that are inevitably mixed with the thermoplastic resin as the ethylene-vinyl acetate copolymer. Means to be.

-Vinyl acetate copolymerization ratio In the ethylene-vinyl acetate copolymer in the high-frequency dielectric heating adhesive sheet, the copolymerization ratio of vinyl acetate (vinyl acetate copolymerization ratio) is preferably 3% by mass or more, and 5% by mass. More preferably, it is more preferably 10% by mass or more.
In the ethylene-vinyl acetate copolymer in the high-frequency dielectric heating adhesive sheet, the copolymerization ratio of vinyl acetate is preferably 40% by mass or less, more preferably 30% by mass or less, and 27% by mass or less. It is more preferable to have.
If the copolymerization ratio of vinyl acetate in the ethylene-vinyl acetate copolymer is 3% by mass or more, the surface free energy is unlikely to be attenuated even after the surface of the high-frequency dielectric heating adhesive sheet is modified. If the attenuation of the surface free energy is small, it is possible to prevent the problem that the strong adhesive strength with the first adherend cannot be obtained with the passage of time.
When the copolymerization ratio of vinyl acetate in the ethylene-vinyl acetate copolymer is 40% by mass or less, tack is less likely to occur during film formation of the high-frequency dielectric heating adhesive sheet, and the thickness accuracy of the high-frequency dielectric heating adhesive sheet is improved. If tack occurs during film formation, the high-frequency dielectric heating adhesive sheet adheres to the sheet transport member (for example, roll) in the sheet manufacturing apparatus, so that horizontal stripes or wrinkles are likely to occur on the sheet.

-Average molecular weight The average molecular weight (weight average molecular weight) of the ethylene-vinyl acetate copolymer is usually preferably 5000 or more, more preferably 10,000 or more, and further preferably 20,000 or more.
The average molecular weight (weight average molecular weight) of the ethylene-vinyl acetate copolymer is preferably 300,000 or less, more preferably 200,000 or less, and further preferably 100,000 or less.
When the weight average molecular weight of the ethylene-vinyl acetate copolymer is 5000 or more, it is possible to prevent the heat resistance and adhesive strength of the high-frequency dielectric heating adhesive sheet from being significantly reduced.
When the weight average molecular weight of the ethylene-vinyl acetate copolymer is 300,000 or less, it is possible to prevent the weldability and the like when the dielectric heat treatment is carried out from being significantly lowered.
The weight average molecular weight of the ethylene-vinyl acetate copolymer can be measured by the ultimate viscosity method in accordance with, for example, JIS K 7376-3 (1999).

(Dielectric filler)
The dielectric filler is a filler that generates heat at high frequencies.
The dielectric filler is preferably a filler that generates heat when a high frequency voltage having a frequency range of 3 MHz or more and 300 MHz or less is applied. The dielectric filler is preferably a filler that generates heat when a high frequency such as a frequency of 13.56 MHz, 27.12 MHz or 40.68 MHz is applied among the frequency range of 3 MHz or more and 300 MHz or less.

-Types Dielectric fillers are zinc oxide, silicon carbide (SiC), anatase-type titanium oxide, barium titanate, barium titanate, lead titanate, potassium niobate, rutyl-type titanium oxide, hydrated aluminum silicate, alkali. It is preferable to use one kind or a combination of two or more kinds of inorganic materials having water of crystallization such as hydrated aluminosilicate of metal or inorganic materials having water of crystallization such as hydrated aluminosilicate of alkaline earth metal.
The dielectric filler is preferably at least one selected from the group consisting of zinc oxide, anatase-type titanium oxide, barium titanate and silicon carbide.
Among the exemplified dielectric fillers, the dielectric filler is zinc oxide because there are many types, it can be selected from various shapes and sizes, and the adhesive properties and mechanical properties of the high-frequency dielectric heating adhesive sheet can be improved according to the application. Is even more preferable. By using zinc oxide as the dielectric filler, a colorless high-frequency dielectric heating adhesive sheet can be obtained. Zinc oxide has the lowest density among the dielectric fillers, so when the adherend is bonded using a high-frequency dielectric heating adhesive sheet containing zinc oxide as the dielectric filler, and when a sheet containing another dielectric filler is used. In comparison, the total weight of the bonded body is unlikely to increase. Zinc oxide is not too hard among ceramics, so it does not easily damage the equipment for manufacturing high-frequency dielectric heating adhesive sheets. Since zinc oxide is an inert oxide, it causes little damage to the thermoplastic resin even when blended with the thermoplastic resin.

-Volume content The dielectric filler is preferably contained in the high-frequency dielectric heating adhesive sheet in an amount of 3% by volume or more, more preferably 5% by volume or more, and further preferably 8% by volume or more.
The dielectric filler is preferably contained in the high-frequency dielectric heating adhesive sheet in an amount of 50% by volume or less, more preferably 40% by volume or less, further preferably 35% by volume or less, and more preferably 25% by volume or less. Is even more preferable.
When the high-frequency dielectric heating adhesive sheet contains 3% by volume or more of the dielectric filler, it is easy to firmly bond the first adherend and the second adherend, which are different materials to each other.
Since the high-frequency dielectric heating adhesive sheet contains 50% by volume or less of the dielectric filler, it is easy to obtain flexibility as a sheet and prevent deterioration of toughness. Therefore, the high-frequency dielectric heating adhesive sheet has a desired shape in a subsequent step. Easy to process.

Since the high-frequency dielectric heating adhesive sheet according to the present embodiment contains the ethylene-vinyl acetate copolymer and the dielectric filler, it is dielectric to the total volume of the ethylene-vinyl acetate copolymer and the dielectric filler. The volume content of the filler is preferably 3% by volume or more, more preferably 5% by volume or more, and further preferably 8% by volume or more. The volume content of the dielectric filler is preferably 50% by volume or less, more preferably 40% by volume or less, and 35% by volume or less, based on the total volume of the ethylene-vinyl acetate copolymer and the dielectric filler. Is even more preferable, and 25% by volume or less is even more preferable.

-Average particle size The average particle size of the dielectric filler is preferably 1 μm or more, more preferably 2 μm or more, and further preferably 3 μm or more.
The average particle size of the dielectric filler is preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less.
When the average particle size of the dielectric filler is 1 μm or more and 30 μm or less, the high-frequency dielectric heating adhesive sheet exhibits high heat generation performance when a high frequency is applied, and makes the first adherend and the second adherend more compatible. Can be firmly adhered in a short time. Further, when the average particle size of the dielectric filler is 30 μm or less, it is possible to prevent the strength of the high-frequency dielectric heating adhesive sheet from decreasing.

The average particle size of the dielectric filler is measured by the following method. The particle size distribution of the dielectric filler is measured by the laser diffraction / scattering method, and the volume average particle size is calculated from the results of the particle size distribution measurement according to JIS Z 8819-2: 2001.

In the high-frequency dielectric heating adhesive sheet according to the present embodiment, it is preferable that the average particle size _DF of the dielectric filler and the thickness T of the high-frequency dielectric heating adhesive sheet satisfy the relationship of _{1 ≦ T / D F ≦ 2500.}
The T / D _F is preferably 1 or more, preferably 2 or more, preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more. When T / D _F is 1 or more, it is possible to prevent a decrease in adhesive strength due to contact between the dielectric filler and the adherend during adhesion.
The T / D _F is preferably 2500 or less, preferably 2000 or less, preferably 1750 or less, more preferably 1000 or less, further preferably 500 or less, and 100 or less. Is even more preferable, and 50 or less is even more preferable. When the T / D _F is 2500 or less, the load on the sheet manufacturing apparatus can be suppressed when the high-frequency dielectric heating adhesive sheet is manufactured.

(Additive)
The high-frequency dielectric heating adhesive sheet according to the present embodiment may or may not contain an additive.

When the high-frequency dielectric heating adhesive sheet according to the present embodiment contains an additive, the additive includes, for example, a tackifier, a plasticizer, a wax, a colorant, an antioxidant, an ultraviolet absorber, an antibacterial agent, and a coupling agent. , Viscosity modifiers, organic fillers, inorganic fillers and the like. Organic fillers as additives and inorganic fillers are different from dielectric fillers.

The tackifier and the plasticizer can improve the melting characteristics and the adhesive characteristics of the high-frequency dielectric heating adhesive sheet.
Examples of the tackifier include rosin derivatives, polyterpene resins, aromatic-modified terpene resins, hydrides of aromatic-modified terpene resins, terpene phenol resins, kumaron inden resins, aliphatic petroleum resins, aromatic petroleum resins, and aromatics. Examples include hydrides of group petroleum resins.
Examples of the plasticizer include petroleum-based process oils, natural oils, dialkyl dibasates, and low molecular weight liquid polymers. Examples of petroleum-based process oils include paraffin-based process oils, naphthenic process oils, aromatic procelus oils, and the like. Examples of the natural oil include castor oil, tall oil and the like. Examples of the dialkyl dibasate include dibutyl phthalate, dioctyl phthalate, and dibutyl adipate. Examples of the low molecular weight liquid polymer include liquid polybutene and liquid polyisoprene.

When the high-frequency dielectric heating adhesive sheet according to the present embodiment contains an additive, the content of the additive in the high-frequency dielectric heating adhesive sheet is usually 0.01% by mass or more based on the total amount of the high-frequency dielectric heating adhesive sheet. Is more preferable, 0.05% by mass or more is more preferable, and 0.1% by mass or more is further preferable. The content of the additive in the high-frequency dielectric heating adhesive sheet is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less.

The high-frequency dielectric heating adhesive sheet according to the present embodiment preferably does not contain carbon or a carbon compound containing carbon as a main component (for example, carbon black or the like) and a conductive substance such as metal. The content of the conductive substance is preferably 5% by mass or less, more preferably 1% by mass or less, and 0.1% by mass or less, based on the total amount of the high-frequency dielectric heating adhesive sheet. Is even more preferable, and 0% by mass is even more preferable.
When the content of the conductive substance in the high-frequency dielectric heating adhesive sheet is 5% by mass or less, it becomes easy to prevent the problem of carbonization of the adhesive portion and the adherend due to electrical dielectric breakdown during the dielectric heat treatment.

In the high-frequency dielectric heating adhesive sheet according to the present embodiment, each of the above components is premixed and kneaded using a known kneading device such as an extruder and a heat roll, and extrusion molding, calendar molding, injection molding, and injection molding are performed. It can be manufactured by a known molding method such as casting molding.

The total mass of the thermoplastic resin and the dielectric filler is preferably 80% by mass or more, more preferably 90% by mass or more, and 99, based on the total mass of the high-frequency dielectric heating adhesive sheet according to the present embodiment. It is more preferably mass% or more.

(Subject)
In the high-frequency dielectric heating adhesive sheet according to the present embodiment, a first adherend containing any resin selected from the group consisting of acrylic resin, polyurethane resin and polyester resin is adhered to the first surface. , Used to adhere a second adherend made of a polyolefin resin to the second surface.

-First adherend The surface of the first adherend is in direct contact with the first surface of the high-frequency dielectric heating adhesive sheet. The surface of the first adherend is composed of any resin selected from the group consisting of acrylic resin, polyurethane resin and polyester resin. It is also preferable that the entire first adherend is composed of any resin selected from the group consisting of acrylic resins, polyurethane resins and polyester resins. It is also preferable that a part of the surface of the first adherend is composed of any resin selected from the group consisting of acrylic resin, polyurethane resin and polyester resin. The area of the portion composed of any resin selected from the group consisting of the acrylic resin, the polyurethane resin and the polyester resin in the area of the entire surface of the first adherend is 60% or more. It is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. When the first adherend has a multi-layer structure, the layer located on the outermost surface of the first adherend is selected from the group consisting of an acrylic resin, a polyurethane resin, and a polyester resin. It is also preferable that it is composed of the above resin.

Examples of the acrylic resin include polymers of (meth) acrylic acid ester, and examples thereof include polymers or copolymers having a structural unit derived from (meth) acrylic acid ester. As the (meth) acrylic acid ester-based copolymer, a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, a monomer containing a functional group having an active hydrogen, and the like are optionally used. Examples thereof include a copolymer with the monomer of. In addition, in this specification, "(meth) acrylic acid" is a concept including both "acrylic acid" and "methacrylic acid".

Examples of the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, butyl (meth) acrylic acid, and (meth). ) Pentyl acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, (meth) Examples thereof include myristyl acrylate (meth), palmityl (meth) acrylate, and stearyl (meth) acrylate. As the (meth) acrylic acid alkyl ester, one type may be used alone, or two or more types may be mixed and used.

Examples of the monomer containing a functional group having active hydrogen include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2 (meth) acrylate. Hydromer group-containing monomers such as (meth) acrylic acid hydroxyalkyl esters such as -hydroxybutyl, 3-hydroxybutyl (meth) acrylic acid, 4-hydroxybutyl (meth) acrylic acid; acrylamide, methacrylic acid, N-methylacrylamide, Amid group-containing monomers such as N-methylmethacrylate, N-methylolacrylamide, and N-methylolmethacrylate; monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate. , (Meta) monoethylaminopropyl acrylate and the like (meth) monoalkylaminoalkyl acrylate; carboxylic acids having an ethylenically unsaturated bond such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. And so on. As the monomer containing a functional group having active hydrogen, one type may be used alone, or two or more types may be mixed and used.

Polyurethane resin refers to a polymer that has a urethane bond in the main chain. Examples of the polyurethane-based resin include a resin obtained by reacting a polyisocyanate with a polyol.

Examples of the polyisocyanate include aromatic polyisocyanates represented by tolylene diisocyanate, diphenyldimethane isocyanate and polymethylene polyphenylene polyisocyanate, and aliphatic polyisocyanates represented by hexamethylene diisocyanate and xylylene diisocyanate. Functional isocyanates can be mentioned. The aliphatic polyisocyanate is not particularly limited, but 1,6-hexamethylene diisocyanate is preferable from the viewpoint of weather resistance. One type of polyisocyanate may be used alone, or two or more types may be used in combination.

Examples of the polyhydric alcohol include polyether polyols, polyester polyols, polyacrylate polyols, polycarbonate polyols and the like. One type of polyhydric alcohol may be used alone, or two or more types may be used in combination.

Polyester-based resin refers to a polymer having an ester bond in the main chain. As the polyester resin, for example, a polyester copolymer resin obtained by copolymerizing a dicarboxylic acid and a glycol compound is preferable.
Examples of the dicarboxylic acid include aromatic dicarboxylic acids such as terephthalic acid, phthalic acid, isophthalic acid, sulfoterephthalic acid, and 2,6-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as oxalic acid, sebacic acid, succinic acid, and adipic acid. Alicyclic dicarboxylic acids such as acids, 1,3-cyclohexanedicarboxylic acids, 1,3-cyclopentanedicarboxylic acids, 1,2-cyclohexanedicarboxylic acids, 1,2-cyclopentanedicarboxylic acids, and 1,4-cyclohexanedicarboxylic acids. Is preferably used.
Examples of the glycol compound include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, and the like. 1,4-Cyclohexanedimethanol, p-xylene glycol, triethylene glycol and the like are preferably used.

-Second adherend The surface of the second adherend that is in direct contact with the second surface of the high-frequency dielectric heating adhesive sheet is made of a polyolefin resin. The polyolefin-based resin in the second adherend is not particularly limited. Examples of the polyolefin-based resin in the second adherend include, for example.
(PO1) Resin made of homopolymer such as polyethylene, polypropylene, polybutene or polymethylpentene,
(PO2) An α-olefin resin composed of a copolymer obtained by copolymerizing a monomer selected from the group consisting of ethylene, propylene, butene, hexene, octene, 4-methylpentene and the like.
(PO3) Examples thereof include polyolefin resins having a polar group such as an olefin-vinyl acetate copolymer and a maleic anhydride-modified polyolefin.
The polyolefin-based resin in the second adherend is preferably polyethylene or an ethylene-based copolymer, and the ethylene-based copolymer is preferably an ethylene-vinyl acetate copolymer.

The shape of the first adherend and the shape of the second adherend are not particularly limited, but are preferably sheet-like. The shape of the first adherend and the second adherend may be made of the same materials as described above, and the shape of the first adherend and the shape and dimensions of the second adherend are the same as each other. But it can be different.

[How to use high-frequency dielectric heating adhesive sheet]
By using the high-frequency dielectric heating adhesive sheet according to the present embodiment, the first adherend and the second adherend can be adhered to each other.
As a method of using the high-frequency dielectric heating adhesive sheet according to the present embodiment, the high-frequency dielectric heating adhesive sheet according to the present embodiment is sandwiched between the first adherend and the second adherend to be 3 MHz or more. When a high-frequency voltage of 300 MHz or less is applied to prepare a bonded body in which the first adherend and the second adherend are adhered to each other, and the bonded body is subjected to a tensile shear test. , At least one of the first adherend and the second adherend is destroyed, or the tensile shear force is preferably 0.2 MPa or more, more preferably 0.5 MPa or more, and 1 MPa. The above is more preferable.
The tensile shear test can be carried out by the method described in Examples described later. The tensile shear force can be measured by the method described in Examples described later.

[Adhesion method]
The bonding method according to the present embodiment is a bonding method using the high-frequency dielectric heating adhesive sheet according to the present embodiment.
In the bonding method according to the present embodiment, the first adherend and the second adherend are adhered to each other.
The bonding method according to the present embodiment includes the following steps P1 and P2. Further, it is also preferable that the bonding method according to the present embodiment further includes the following step P3.

・ Process P1
Step P1 is a step of sandwiching the high-frequency dielectric heating adhesive sheet according to the present embodiment between the first adherend and the second adherend. In step P1, a first adherend containing any resin selected from the group consisting of an acrylic resin, a polyurethane resin, and a polyester resin is brought into contact with the first surface of the high-frequency dielectric heating adhesive sheet. Further, in step P1, a second adherend made of a polyolefin resin is brought into contact with the second surface of the high-frequency dielectric heating adhesive sheet.

The high-frequency dielectric heating adhesive sheet may be sandwiched between the first adherend and the second adherend so that the first adherend and the second adherend can be adhered to each other. The high-frequency dielectric heating adhesive sheet may be sandwiched between the first adherend and the second adherend at a plurality of places or on the entire surface. From the viewpoint of improving the adhesive strength between the first adherend and the second adherend, a high-frequency dielectric heating adhesive sheet is applied over the entire adhesive surface between the first adherend and the second adherend. It is preferable to hold it. Further, as one aspect of sandwiching the high-frequency dielectric heating adhesive sheet in a part between the first adherend and the second adherend, the first adherend and the second adherend are used. An embodiment in which a high-frequency dielectric heating adhesive sheet is arranged in a frame shape along the outer periphery of the adhesive surface and is sandwiched between the first adherend and the second adherend can be mentioned. By arranging the high-frequency dielectric heating adhesive sheet in a frame shape in this way, the adhesive strength between the first adherend and the second adherend can be obtained, and the high-frequency dielectric heating adhesive sheet can be spread over the entire adhesive surface. The weight of the joint can be reduced as compared with the case where it is arranged. Further, according to one aspect in which the high-frequency dielectric heating adhesive sheet is sandwiched between a part of the first adherend and the second adherend, the size of the high-frequency dielectric heating adhesive sheet to be used can be reduced, so that the adhesive can be adhered. The high-frequency dielectric heating treatment time can be shortened as compared with the case where the high-frequency dielectric heating adhesive sheet is arranged over the entire surface.

・ Process P2
In step P2, a high-frequency voltage of 3 MHz or more and 300 MHz or less is applied to the high-frequency dielectric heating adhesive sheet sandwiched between the first adherend and the second adherend in step P1 to perform the first step. This is a step of adhering the adherend to the second adherend with a high-frequency dielectric heating adhesive sheet.
For example, by using a dielectric heating adhesive device, a high frequency voltage can be applied to the high frequency dielectric heating adhesive sheet.

・ Process P3
Step P3 is a step performed before step P1.
Step P3 is a step of modifying the first surface of the high-frequency dielectric heating adhesive sheet ^{to adjust the surface free energy of the first surface to 40 mJ / m 2} or more.
In the bonding method according to the present embodiment, the reforming treatment in step P3 is preferably at least one of corona treatment and plasma treatment. The reforming treatment can be carried out using a known reforming treatment apparatus.

FIG. 2 shows a schematic diagram illustrating a high-frequency dielectric heating treatment using the high-frequency dielectric heating adhesive sheet and the dielectric heating device according to the present embodiment.

(Dielectric heating adhesive device)
FIG. 2 shows a schematic view of the dielectric heating adhesive device 30.
The dielectric heating adhesive device 30 includes a first high frequency application electrode 31, a second high frequency application electrode 32, and a high frequency power supply 33.
The first high frequency application electrode 31 and the second high frequency application electrode 32 are arranged so as to face each other. The first high frequency application electrode 31 and the second high frequency application electrode 32 have a press mechanism. By this press mechanism, the first adherend 110, the high frequency dielectric heating adhesive sheet 10 and the second adherend 120 can be pressurized between the first high frequency application electrode 31 and the second high frequency application electrode 32. ..

When the first high frequency application electrode 31 and the second high frequency application electrode 32 form a pair of flat plate electrodes parallel to each other, such an electrode arrangement type may be referred to as a parallel flat plate type.
It is also preferable to use a parallel plate type high frequency dielectric heating device for applying a high frequency. In the case of a parallel plate type high-frequency dielectric heating device, since the high frequency penetrates the high-frequency dielectric heating adhesive sheet located between the electrodes, the entire high-frequency dielectric heating adhesive sheet can be warmed, and the adherend and the high-frequency dielectric heating adhesive sheet can be heated. Can be bonded in a short time.

A high frequency power supply 33 for applying a high frequency voltage of, for example, a frequency of about 13.56 MHz, a frequency of about 27.12 MHz, or a frequency of about 40.68 MHz is connected to each of the first high frequency application electrode 31 and the second high frequency application electrode 32. There is.
As shown in FIG. 2, the dielectric heating adhesive device 30 performs a dielectric heating treatment via a high-frequency dielectric heating adhesive sheet 10 sandwiched between the first adherend 110 and the second adherend 120. Further, in the dielectric heating adhesive device 30, in addition to the dielectric heating treatment, the first high-frequency application electrode 31 and the second high-frequency application electrode 32 pressurize the first adherend 110 and the second adherend 120. And glue. The first adherend 110 and the second adherend 120 may be adhered to each other by, for example, pressing only by the weight of the adhesive sheet or the adherend without performing the pressure treatment.

When a high-frequency electric field is applied between the first high-frequency application electrode 31 and the second high-frequency application electrode 32, the dielectric filler (not shown) dispersed in the adhesive component of the high-frequency dielectric heating adhesive sheet 10 transfers high-frequency energy. Absorb.
Then, the dielectric filler functions as a heat generating source, and the heat generated by the dielectric filler melts the thermoplastic resin component, and even if the treatment is performed for a short time, finally, the first adherend 110 and the second adherend It can be firmly adhered to the adherend 120.

Since the first high frequency application electrode 31 and the second high frequency application electrode 32 have a press mechanism, they also function as a press device. Therefore, the first adherend 110 and the second adherend 120 are formed by pressurizing the first high-frequency application electrode 31 and the second high-frequency application electrode 32 in the compression direction and heating and melting the high-frequency dielectric heating adhesive sheet 10. Can be adhered more firmly.

(High-frequency dielectric heating bonding conditions)
The high-frequency dielectric heating bonding conditions can be changed as appropriate, but the following conditions are preferable.

The high frequency output is preferably 10 W or more, more preferably 50 W or more, and even more preferably 80 W or more.
The high frequency output is preferably 50,000 W or less, more preferably 20,000 W or less, further preferably 15,000 W or less, further preferably 10,000 W or less, and 1, It is even more preferable that it is 000 W or less.
When the high frequency output is 10 W or more, it is possible to prevent the problem that the temperature does not easily rise during the dielectric heating treatment, so that it is easy to obtain a good adhesive force.
When the high frequency output is 50,000 W or less, it is easy to prevent a problem that temperature control by dielectric heating treatment becomes difficult.

The high frequency application time is preferably 1 second or longer.
The application time of the high frequency is preferably 60 seconds or less, more preferably 45 seconds or less, further preferably 35 seconds or less, further preferably 25 seconds or less, still more preferably 10 seconds or less. ..
If the high frequency application time is 1 second or more, it is possible to prevent the problem that the temperature does not easily rise during the dielectric heating treatment, so that good adhesive strength can be easily obtained.
If the application time of the high frequency is 60 seconds or less, the manufacturing efficiency of the bonded body in which the first adherend and the second adherend are adhered is lowered, the manufacturing cost is increased, and further, the manufacturing cost is increased. It is easy to prevent problems such as thermal deterioration of the adherend.

The frequency of the high frequency to be applied is preferably 1 kHz or higher, more preferably 1 MHz or higher, further preferably 5 MHz or higher, and even more preferably 10 MHz or higher.
The frequency of the high frequency to be applied is preferably 300 MHz or less, more preferably 100 MHz or less, further preferably 80 MHz or less, and even more preferably 50 MHz or less. Specifically, the industrial frequency bands 13.56 MHz, 27.12 MHz or 40.68 MHz assigned by the International Telecommunication Union are also used in the high-frequency dielectric heating bonding method (bonding method) of the present embodiment.

(Effect of this embodiment)
According to the high-frequency dielectric heating adhesive sheet according to the present embodiment, the first adherend containing any resin selected from the group consisting of acrylic resin, polyurethane resin and polyester resin, and the polyolefin resin Can be firmly adhered to the second adherend.

The high-frequency dielectric heating adhesive sheet according to the present embodiment is easier to handle than the case of using an adhesive that requires coating, and the workability at the time of bonding the first adherend and the second adherend is also improved. To do. According to the high-frequency dielectric heating adhesive sheet according to the present embodiment, it can be adhered to an adherend by applying a high frequency for a short time.

The high-frequency dielectric heating adhesive sheet according to this embodiment has excellent water resistance and moisture resistance as compared with general adhesives.

Since the high-frequency dielectric heating adhesive sheet according to the present embodiment does not contain a solvent, the problem of VOC (Volatile Organic Compounds) caused by the adhesive used for adhesion to the adherend is unlikely to occur.

Since the high-frequency dielectric heating adhesive sheet according to the present embodiment is heated by applying a high-frequency voltage, the high-frequency dielectric heating adhesive sheet is locally heated. Therefore, according to the high-frequency dielectric heating adhesive sheet according to the present embodiment, it is easy to prevent a problem that the entire adherend is melted at the time of adhesion to the adherend.

According to the bonding method using the high-frequency dielectric heating adhesive sheet according to the present embodiment, only a predetermined portion can be locally heated from the outside by the dielectric heating bonding device. Therefore, even when the adherend is a large and complicated three-dimensional structure or a large and complicated three-dimensional structure and higher dimensional accuracy is required, the high-frequency dielectric heating adhesive sheet according to the present embodiment can be used. The bonding method used is effective.

Further, according to the high-frequency dielectric heating adhesive sheet according to the present embodiment, the thickness of the high-frequency dielectric heating adhesive sheet can be appropriately controlled. Therefore, the high-frequency dielectric heating adhesive sheet according to the present embodiment can be applied to the roll-to-roll method, and can be adjusted to the adhesion area with the adherend and the shape of the adherend by punching or the like. , High frequency dielectric heating adhesive sheet can be processed into any area and shape. Therefore, the high-frequency dielectric heating adhesive sheet according to the present embodiment has a great advantage from the viewpoint of the manufacturing process.

[Modification of Embodiment]
The present invention is not limited to the above embodiment. The present invention can include modifications and improvements to the extent that the object of the present invention can be achieved.

The high-frequency dielectric heating adhesive sheet may have an adhesive portion. By having the adhesive portion, when the high-frequency dielectric heating adhesive sheet is sandwiched between the adherends, it is possible to prevent misalignment and arrange the adhesive sheet at an accurate position. The adhesive portion may be provided on one surface of the high-frequency dielectric heating adhesive sheet or may be provided on both sides. Further, the adhesive portion may be partially provided with respect to the surface of the high-frequency dielectric heating adhesive sheet. The high-frequency dielectric heating adhesive sheet can firmly bond the first adherend and the second adherend even when it does not have an adhesive portion.

The high-frequency dielectric heating treatment is not limited to the dielectric heating and bonding apparatus in which the electrodes described in the above embodiment are arranged to face each other, and a lattice electrode type high-frequency dielectric heating apparatus may be used. The lattice electrode type high-frequency dielectric heating device has lattice electrodes in which first polar electrodes and second polarity electrodes having opposite polarities to the first polarity electrodes are alternately arranged on the same plane at regular intervals. ..
For example, in the case of manufacturing a bonded body in which the end portion of the first adherend and the end portion of the second adherend are overlapped and adhered, the end portion is on the first adherend side or the second adherend side. A lattice electrode type high frequency dielectric heating device is arranged to apply high frequency.

When the first adherend and the second adherend are adhered to each other by using a lattice electrode type high-frequency dielectric heating device, the first lattice electrode is arranged on the side of the first adherend, and the second. A second lattice electrode is arranged on the adherend side, and the first adherend, the high-frequency dielectric heating adhesive sheet and the second adherend are placed between the first lattice electrode and the second lattice electrode. A high frequency may be applied at the same time by sandwiching it.

When the first adherend and the second adherend are adhered to each other by using a lattice electrode type high-frequency dielectric heating device, the first adherend and the second adherend are subjected to one surface side. A lattice electrode may be arranged and a high frequency may be applied, and then a lattice electrode may be arranged on the other surface side of the first adherend and the second adherend and the high frequency may be applied.

It is also preferable to use a lattice electrode type high frequency dielectric heating device for applying high frequency. By using a lattice electrode type high-frequency dielectric heating device, the surface layer of the first adherend and the second adherend is not affected by the thickness of the first adherend and the second adherend. The adherends can be bonded to each other by dielectric heating from the side, for example, the adherend side where the distance to the high-frequency dielectric heating adhesive sheet is short. Further, by using a lattice electrode type high frequency dielectric heating device, it is possible to realize energy saving in the production of the bonded body.

In addition, in the figure, an embodiment using a dielectric heating adhesive device in which electrodes are arranged to face each other is illustrated for simplification.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples.

[Method for manufacturing high-frequency dielectric heating adhesive sheet]
The adhesive sheets according to Examples 1 to 16 and Comparative Examples 1 to 6 were produced as follows.
The thermoplastic resin and dielectric filler shown in Table 1 were premixed in a container. By supplying the premixed material to the hopper of a 30 mmφ twin-screw extruder, setting the cylinder set temperature to 180 ° C or higher and 200 ° C or lower, setting the die temperature to 200 ° C, and melting and kneading the premixed material. , Granular pellets were obtained. Next, the obtained granular pellets were put into the hopper of a single-screw extruder equipped with a T-die, and a film-like melt-kneaded product was obtained from the T-die under the conditions of a cylinder temperature of 200 ° C. and a die temperature of 200 ° C. A high-frequency dielectric heating adhesive sheet having a thickness of 400 μm was produced by extruding and cooling with a cooling roll.

[Modification process]
One surface (first surface) of the produced high-frequency dielectric heating adhesive sheet was modified as shown in Table 1.

(Corona processing)
The first surface of the produced high-frequency dielectric heating adhesive sheet was subjected to corona treatment. For the corona treatment, a corona treatment device (“AGF-B10” manufactured by Kasuga Electric Co., Ltd.) was used. The line speed and output of the corona processing apparatus were adjusted, and corona processing was performed with a discharge amount of 400 W · min / m ² .

(Plasma processing)
Further, the first surface of the produced high-frequency dielectric heating adhesive sheet was subjected to plasma treatment. A plasma processing apparatus (“MODEL KI-110” manufactured by Izumi Kogyo Co., Ltd.) was used for plasma processing. The conditions for plasma treatment were an output of 100 W in the atmosphere.

[High frequency adhesiveness]
The produced high-frequency dielectric heating adhesive sheet was cut into a size of 25 mm × 12.5 mm. The first adherend and the second adherend shown in Table 1 were prepared. The size of the first adherend and the second adherend was 25 mm × 100 mm. A high-frequency dielectric heating adhesive sheet cut to the above-mentioned size was sandwiched between the first adherend and the second adherend. At this time, the first surface of the high-frequency dielectric heating adhesive sheet was brought into contact with the first adherend, and the second surface was brought into contact with the second adherend. The first adherend, the high-frequency dielectric heating adhesive sheet and the second adherend were fixed between the electrodes of the high-frequency dielectric heating device (“YRP-400TA” manufactured by Yamamoto Vinita Co., Ltd.). In the fixed state, a high frequency was applied under the following high frequency application conditions to bond the high frequency dielectric heating adhesive sheet and the adherend to prepare an initial test piece.

・ High frequency application condition Frequency: 40.68MHz
Output: 100W
Application time: 10 seconds

Regarding the modified high-frequency dielectric heating adhesive sheet, a time-dependent test piece was prepared in the same manner as the above-mentioned initial test piece using the high-frequency dielectric heating adhesive sheet 30 days after the modification treatment.

[Adhesive force (tensile shear force)]
The tensile shear force as the adhesive force was measured for the initial test piece and the time-lapse test piece obtained by the high-frequency adhesiveness evaluation. A universal tensile tester (Instron 5581, manufactured by Instron) was used to measure the tensile shear force. The tensile speed in the measurement of the tensile shear force was set to 100 mm / min. The tensile shear force was measured according to JIS K 6850: 1999. The fracture mode of the test piece at the time of measuring the tensile shear force was observed, and the adhesive force was evaluated according to the following evaluation criteria. Table 1 shows the evaluation results of the adhesive strength. In Table 1, in the case of evaluation A2, evaluation F1 or evaluation F2, the values of tensile shear force are listed. The values of the tensile shear force of Comparative Example 3 are the measured values of the test piece over time (after 30 days have passed), and the values of the tensile shear force other than Comparative Example 3 are the measured values of the initial test piece.

-Evaluation Criteria Evaluation A1: At least one of the first adherend and the second adherend was destroyed.
Evaluation A2: The high-frequency dielectric heating adhesive sheet coagulated and fractured.
Evaluation F1: Delamination was performed between the high-frequency dielectric heating adhesive sheet and the first adherend.
Evaluation F2: Delamination was performed between the high-frequency dielectric heating adhesive sheet and the second adherend.

[Average particle size]
The particle size distribution of the dielectric filler was measured by the laser diffraction / scattering method. From the result of particle size distribution measurement, the volume average particle size was calculated according to JIS Z 8819-2: 2001. The calculated average particle size (volume average particle size) of the dielectric filler is shown in Table 1.

[Surface free energy]
The contact angle (measurement temperature: 25 ° C.) of various droplets is measured, and the contact angle is determined by the Kitazaki-Hata method based on the value of the contact angle. Diiodomethane, 1-bromonaphthalene, and distilled water are used as droplets, and using DM-701 manufactured by Kyowa Interface Science Co., Ltd., the contact angle (measurement temperature) is based on JIS R 3257: 1999 by the intravenous drop method. : 25 ° C.) was measured, and the surface free energy was determined by the Kitazaki-Hata method based on the value of the contact angle. The unit of surface free energy is mJ / m ² .
The surface free energy was measured immediately after the surface of the high-frequency dielectric heating adhesive sheet was modified and after 30 days had passed. Table 1 shows the measurement results of the surface free energy.

[Tension breaking elongation]
The high-frequency dielectric heating adhesive sheet produced in the above Examples and Comparative Examples was cut into test pieces of 15 mm (TD direction) × 150 mm (MD direction), and in accordance with JIS K 7161-1: 2014 and JIS K 7127: 1999. , The tensile elongation at break (%) at 23 ° C. was measured. Specifically, the above test piece is set to a distance between chucks of 100 mm with a tensile tester (manufactured by Shimadzu Corporation, Autograph AG-IS 500N), and then a tensile test is performed at a speed of 200 mm / min to perform tensile fracture. Elongation (%) was measured.

[Dielectric property]
The produced high-frequency dielectric heating adhesive sheet was cut into a size of 30 mm × 30 mm. The cut high-frequency dielectric heating adhesive sheet was measured for dielectric constant (ε') and dielectric loss tangent (tan δ), respectively, using an RF impedance material analyzer E4991A (manufactured by Agilent) under the condition of a frequency of 40.68 MHz at 23 ° C. .. Based on the measurement results, the value of the dielectric property (tan δ / ε') was calculated. For example, the dielectric properties (tan δ / ε') of the high-frequency dielectric heating adhesive sheet according to Examples 1, 11 and 12 were as follows.
Example 1: 0.016
Example 11: 0.008
Example 12: 0.038

The explanation of the symbols, etc. shown in Table 1 is as follows.

-Thermoplastic resin EVA1: Ethylene-vinyl acetate copolymer (copolymerization ratio of vinyl acetate: 6% by mass)

EVA2: Ethylene-vinyl acetate copolymer (copolymerization ratio of vinyl acetate: 16% by mass)

EVA3: Ethylene-vinyl acetate copolymer (copolymerization ratio of vinyl acetate: 25% by mass)

EVA4: Ethylene-vinyl acetate copolymer (copolymerization ratio of vinyl acetate: 28% by mass)

VA ratio: Copolymerization ratio of vinyl acetate PE: Polyethylene MAH-PE: Maleic anhydride-modified polyethylene

Dielectric filler ZnO: Zinc oxide (“LPZINC11” manufactured by Sakai Chemical Industry Co., Ltd., average particle size: 11 μm, and “LPZINC5” manufactured by Sakai Chemical Industry Co., Ltd., average particle size: 5 μm)

・ First adherend ACR1: Acrylic film ("Parapure JS grade" manufactured by Kuraray Co., Ltd., 25 mm x 100 mm x 0.2 mm)
PU: Polyurethane film ("PUK-350" manufactured by Kuraray Plastics Co., Ltd., 25 mm x 100 mm x 0.35 mm)
PES: Polyester film ("S10 Lumirror" manufactured by Toray Industries, Inc., 25 mm x 100 mm x 0.188 mm)
ACR2: Acrylic ("Ultramax U-21 Silver" manufactured by Hiraoka Orizome Co., Ltd., 25 mm x 100 mm x 0.47 mm)
When the test piece was prepared using ACR2, a high-frequency dielectric heating adhesive sheet was adhered to the acrylic coated surface of ACR2.

-Second adherend EVA: Ethylene-vinyl acetate copolymer ("Olefin Tarpaulin EVA25" manufactured by Ishizuka Co., Ltd., 25 mm x 100 mm x 0.32 mm)
PE: Polyethylene (sheet molded from "Sumikasen L705" manufactured by Sumitomo Chemical Co., Ltd., 25 mm x 100 mm x 0.40 mm)

Since the high-frequency dielectric heating adhesive sheets according to Examples 1 to 16 ^{had a sheet surface having a surface free energy of 40 mJ / m 2} or more immediately after the modification treatment and 30 days after the modification treatment, the modification treatment was performed. In the evaluation of the adhesive strength immediately after the modification and the adhesive strength 30 days after the modification, at least one of the first adherend (ACR1, ACR2, PU or PES) and the second adherend (EVA or PE). Was broken, or the high-frequency dielectric heating adhesive sheet was coagulated and broken, and was evaluated as A1 or A2.
The high-frequency dielectric heating adhesive sheet according to Example 6 contained 80% by volume of EVA having a VA ratio of 28% by mass, and the sheet had horizontal stripes and wrinkles, resulting in poor appearance.
Since the surface free energy of the sheet surface of the high-frequency dielectric heating adhesive sheet according to Comparative Examples 1, 2 and 4 was ^{less than 40 mJ / m 2} , the high-frequency dielectric heating adhesive sheet and the high-frequency dielectric heating adhesive sheet were evaluated in the adhesive strength immediately after the modification treatment. Delamination was performed with the first adherend (ACR1), and the evaluation was F1.
In the high-frequency dielectric heating adhesive sheet according to Comparative Example 3, the surface free energy of the sheet surface decreased to less than ^{40 mJ / m 2 30 days after the modification.} As a result, the high-frequency dielectric heating adhesive sheet according to Comparative Example 3 was delaminated between the high-frequency dielectric heating adhesive sheet and the first adherend (ACR1) in the evaluation of the adhesive strength 30 days after the modification. , F1 evaluation.
The high-frequency dielectric heating adhesive sheets according to Comparative Examples 5 and 6 had a sheet surface having a ^{surface free energy of 40 mJ / m 2 or more immediately after the modification treatment and 30 days after the modification, but were thermoplastic.} Since it contained an acrylic resin or a polyester resin as the resin and did not contain an ethylene-vinyl acetate copolymer, it was delaminated between the high-frequency dielectric heating adhesive sheet and the second adherend (EVA). It was an F2 evaluation.

The high-frequency dielectric heating adhesive sheet according to the present invention comprises a first adherend containing any resin selected from the group consisting of acrylic resins, polyurethane resins and polyester resins, and a second composed of polyolefin resins. It can be used as a sheet-like adhesive for adhering to the adherend of. For example, the high-frequency dielectric heating adhesive sheet according to the present invention can be used for adhering a cloth, a non-woven fabric, a resin sheet, or a fiber-reinforced resin sheet (tarpaulin).

10 ... High frequency dielectric heating adhesive sheet, 11 ... First surface, 110 ... First adherend, 12 ... Second surface, 120 ... Second adherend, 30 ... Dielectric heating adhesive device, 31 ... First 1 High frequency application electrode, 32 ... Second high frequency application electrode, 33 ... High frequency power supply.

Claims (14)

1. High-frequency dielectric heating adhesive sheet
   It contains an ethylene-vinyl acetate copolymer and a dielectric filler that generates heat at high frequencies.
   It has a first surface and a second surface opposite to the first surface.
   The surface free energy of the first surface is 40 mJ / m ² or more.
   A first adherend containing any resin selected from the group consisting of an acrylic resin, a polyurethane resin, and a polyester resin is adhered to the first surface, and the second surface is made of a polyolefin resin. Used to bond the second adherend,
   High frequency dielectric heating adhesive sheet.
2. In the high-frequency dielectric heating adhesive sheet according to claim 1,
   The vinyl acetate copolymerization ratio of the ethylene-vinyl acetate copolymer is 3% by mass or more and 40% by mass or less.
   High frequency dielectric heating adhesive sheet.
3. In the high-frequency dielectric heating adhesive sheet according to claim 1 or 2.
   The dielectric filler generates heat when a high frequency voltage of 3 MHz or more and 300 MHz or less is applied.
   High frequency dielectric heating adhesive sheet.
4. The high-frequency dielectric heating adhesive sheet according to any one of claims 1 to 3.
   The dielectric filler is contained in the high-frequency dielectric heating adhesive sheet in an amount of 3% by volume or more and 50% by volume or less.
   High frequency dielectric heating adhesive sheet.
5. In the high-frequency dielectric heating adhesive sheet according to any one of claims 1 to 4.
   The average particle size of the dielectric filler is 1 μm or more and 30 μm or less.
   High frequency dielectric heating adhesive sheet.
6. The high-frequency dielectric heating adhesive sheet according to any one of claims 1 to 5.
   The dielectric filler is at least one selected from the group consisting of zinc oxide, anatase-type titanium oxide, barium titanate and silicon carbide.
   High frequency dielectric heating adhesive sheet.
7. The high-frequency dielectric heating adhesive sheet according to any one of claims 1 to 6.
   The thickness of the high-frequency dielectric heating adhesive sheet is 10 μm or more.
   High frequency dielectric heating adhesive sheet.
8. In the high-frequency dielectric heating adhesive sheet according to any one of claims 1 to 7.
   The average particle size _CF of the dielectric filler and the thickness T of the high-frequency dielectric heating adhesive sheet are
   Satisfy the relationship of 1 ≤ T / D _{F ≤ 2500,}
   High frequency dielectric heating adhesive sheet.
9. The high-frequency dielectric heating adhesive sheet according to any one of claims 1 to 8.
   The tensile elongation at break of the high-frequency dielectric heating adhesive sheet is 1% or more.
   High frequency dielectric heating adhesive sheet.
10. In the high-frequency dielectric heating adhesive sheet according to any one of claims 1 to 9.
    The polyolefin-based resin in the second adherend is polyethylene or an ethylene-vinyl acetate copolymer.
    High frequency dielectric heating adhesive sheet.
11. The method for using the high-frequency dielectric heating adhesive sheet according to any one of claims 1 to 10.
    The high-frequency dielectric heating adhesive sheet is sandwiched between the first adherend and the second adherend, and a high-frequency voltage of 3 MHz or more and 300 MHz or less is applied to the first adherend. When a bonded body in which the first adherend and the second adherend are adhered to each other and the joined body is subjected to a tensile shear test, at least the first adherend and the second adherend are formed. One is broken or the tensile shear force is 0.2 MPa or more.
    How to use high frequency dielectric heating adhesive sheet.
12. This is an adhesive method using a high-frequency dielectric heating adhesive sheet.
    The high-frequency dielectric heating adhesive sheet contains an ethylene-vinyl acetate copolymer and a dielectric filler that reacts at high frequencies.
    The high frequency dielectric heating adhesive sheet has a first surface and a second surface opposite to the first surface.
    The surface free energy of the first surface is 40 mJ / m ² or more.
    A first adherend containing any resin selected from the group consisting of an acrylic resin, a polyurethane resin, and a polyester resin is brought into contact with the first surface, and a second adherend made of a polyolefin resin is brought into contact with the first surface. A step of bringing the body into contact with the second surface and sandwiching the high-frequency dielectric heating adhesive sheet between the first adherend and the second adherend.
    A step of applying a high-frequency voltage of 3 MHz or more and 300 MHz or less to the high-frequency dielectric heating adhesive sheet to bond the first adherend and the second adherend with the high-frequency dielectric heating adhesive sheet. Including,
    Adhesion method using a high-frequency dielectric heating adhesive sheet.
13. A bonding method using the high-frequency dielectric heating adhesive sheet according to claim 12.
    Further comprising a step of modifying the first surface to adjust the surface free energy of the first surface to 40 mJ / m ^{2 or more.}
    Adhesion method using a high-frequency dielectric heating adhesive sheet.
14. A bonding method using the high-frequency dielectric heating adhesive sheet according to claim 13.
    The modification treatment is at least one of a corona treatment and a plasma treatment.
    Adhesion method using a high-frequency dielectric heating adhesive sheet.

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