JP2010095632A - Adhesive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive film preventing development of tackiness at the temperature around 40°C without impairing properties of the adhesive film. <P>SOLUTION: The adhesive film comprises the following ingredients (A) to (D): (A) 40-70 mass% of an acrylic resin having a glass temperature (Tg) of 50-90°C; (B) 10-30 mass% of a copolymer of an acrylonitrile and an elastomer component; (C) 5-40 mass% of a mixture of a solid epoxy resin and a liquid epoxy resin; and (D) 0.1-5 mass% of an epoxy hardening agent. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an adhesive film. More specifically, the present invention relates to an intermetal insulating holding adhesive film that bonds two metal members while maintaining insulating properties.
Moreover, this invention relates to the composite metal member formed by joining two metal members with the adhesive film of this invention.

In some cases, it is required to bond metal members while maintaining insulation. For example, it may be required to bond a copper foil to form electrical wiring on a base made of steel or the like.
As means for adhering metal members while maintaining insulation, liquid adhesives such as those described in Patent Document 1 have been conventionally used. However, when a liquid adhesive is used, the film thickness of the adhesive layer may not be constant, and bubbles may remain in the adhesive layer. It has become to.

The adhesive film is a film made of a resin material that exhibits adhesiveness when heated to a predetermined temperature. When metal members are bonded to each other using an adhesive film, thermocompression bonding is performed by a press with the adhesive film interposed between the metal members.
As an adhesive film, what contains an acrylic resin, an epoxy resin, and an epoxy resin hardening | curing agent as an essential component is common (refer patent document 2-patent document 9). The acrylic resin to be included in the adhesive film is highly compatible with other components, so it is easy to mix with other components during film production, easy to form into a film, and excellent in flexibility. To those having a low glass transition point (Tg), specifically, those having a Tg of 10 ° C. or lower, preferably 0 ° C. or lower.

However, since these conventional adhesive films contain an acrylic resin having a low Tg, there is a problem that tack develops even at a relatively low temperature. For example, when an adhesive film is placed on one metal member, the temperature may be about 40 ° C. Even at such a temperature, the conventional adhesive film exhibits tack. When the adhesive film is placed on the metal member, there may be a state where air bubbles are present between the two. When the adhesive film develops tack, it is difficult to remove such bubbles. When thermocompression bonding is performed with a press with air bubbles remaining between the metal member and the adhesive film, the air bubbles expand during thermocompression bonding, causing peeling on the adhesive surface or misalignment of the bonded metal member. May occur.
In addition, the adhesive film before use is stored in a state sandwiched between protective films such as a polyethylene terephthalate (PET) film in order to prevent foreign matter from adhering to the adhesive surface, but when tack appears in the adhesive film, It becomes difficult to isolate the adhesive film from the protective film.

  However, when an acrylic resin having a high Tg is used, since compatibility with other components is low, it becomes difficult to mix with other components at the time of film production, film formation becomes difficult, the film is inferior in flexibility, etc. Cause problems.

JP-A-61-138680 JP 2000-256635 A Japanese Patent Laid-Open No. 2000-256631 JP-A-11-166019 JP 2001-247633 A JP 2000-248025 A JP 2000-248026 A JP 2003-82034 A Japanese Patent Laid-Open No. 7-336026

  SUMMARY OF THE INVENTION In order to solve the above-described problems of the prior art, an object of the present invention is to provide an adhesive film that prevents the occurrence of tack at a temperature around 40 ° C. without impairing the properties of the adhesive film. .

In order to achieve the above object, the present invention provides an adhesive film containing the following components (A) to (D).
(A) Acrylic resin having a glass transition point (Tg) of 50 to 90 ° C. 40 to 70% by mass
(B) Copolymer of acrylonitrile and elastomer component 10 to 30% by mass
(C) Mixture of solid epoxy resin and liquid epoxy resin 5 to 40% by mass
(D) Epoxy curing agent 0.1 to 5% by mass

  It is preferable that the adhesive film of the present invention does not develop tack at a temperature of 40 ° C. or lower and develops tack at a temperature of 50 ° C. or higher.

In the adhesive film of the present invention, the component (A) contains a methyl methacrylate component (x) and a butyl acrylate component (y) in a ratio of x / y = 8/2 to 6/4, A methyl methacrylate / butyl acrylate copolymer having a mass average molecular weight (Mw) of 400,000 to 600,000;
The component (B) is an acrylonitrile-butadiene copolymer containing the acrylonitrile component (m) and the butadiene component (n) in a ratio of m / n = 1/9 to 9/1.
The component (C) is a mixture containing bisphenol A type solid resin (a) and liquid bisphenol F type epoxy resin (b) at a ratio of a / b = 1/9 to 9/1.
The component (D) is preferably an imidazole curing agent.

In the adhesive film of the present invention, the component (A) contains a methyl methacrylate component (x) and a butyl acrylate component (y) in a ratio of x / y = 8/2 to 6/4. And a methyl methacrylate / butyl acrylate copolymer having a mass average molecular weight (Mw) of 400,000 to 600,000,
The component (B) contains an acrylonitrile component, a butadiene component and a methacrylic acid component, and the content ratio of the acrylonitrile component (m) and the butadiene component (n) is m / n = 1/9 to 9 /. 1, an acrylonitrile-butadiene-methacrylic acid copolymer,
The component (C) is a mixture containing bisphenol A type solid resin (a) and liquid bisphenol F type epoxy resin (b) at a ratio of a / b = 1/9 to 9/1.
The component (D) is preferably an imidazole curing agent.

  The present invention also provides a composite metal member in which two metal members are bonded via the adhesive film of the present invention.

Since the adhesive film of the present invention does not exhibit tack at a temperature of 40 ° C. or lower, it is easy to remove bubbles present between the metal member and the adhesive film. For this reason, problems such as peeling on the bonding surface and displacement of the bonded metal member that occur when thermocompression bonding is performed with a press while air bubbles remain are not caused. Moreover, it is easy to isolate an adhesive film from a protective film.
On the other hand, the adhesive film of the present invention can be thermocompression-bonded by a press under the same conditions as conventional adhesive films.
The adhesive film of the present invention has excellent properties required for an intermetal insulating holding adhesive film such as insulation after adhesion, surface hardness after adhesion, resistance to chemicals such as an etching solution, and solder resist can be applied. Yes.

Hereinafter, the adhesive film of the present invention will be described.
The adhesive film of the present invention contains the following components (A) to (D).
(A) Acrylic resin having a glass transition point (Tg) of 50 to 90 ° C. 40 to 70% by mass
(B) Copolymer of acrylonitrile and elastomer component 10 to 30% by mass
(C) Mixture of solid epoxy resin and liquid epoxy resin 5 to 40% by mass
(D) Epoxy curing agent 0.1 to 5% by mass
Hereinafter, each component will be described.

(A) Acrylic resin having a glass transition point (Tg) of 50 to 90 ° C. As described above, in the conventional adhesive film, an acrylic resin having a Tg of 10 ° C. or less, preferably 0 ° C. or less was used. On the other hand, in the adhesive film of the present invention, an acrylic resin having a Tg of 50 to 90 ° C. is used. By using an acrylic resin having a Tg of 50 to 90 ° C., the tack development temperature of the adhesive film is appropriately increased, and tack does not appear at a temperature of 40 ° C. or lower. Therefore, when the adhesive film is placed on the metal member, it is easy to remove the bubbles even if there are bubbles between them. Therefore, by performing thermocompression bonding with a press while air bubbles remain between the metal member and the adhesive film, the possibility of peeling on the adhesive surface or misalignment of the bonded metal member is eliminated. Is done. Moreover, it is easy to isolate the adhesive film before use from the protective film.

The tack | tuck expression temperature of the adhesive film of this invention is 50 degreeC or more, Preferably it is 50-120 degreeC, More preferably, it is 50-100 degreeC, More preferably, it is 60-80 degreeC.
Therefore, since the tack development temperature of the adhesive film does not become extremely high, thermocompression bonding with a press can be performed under the same conditions as those of conventional adhesive films.
In addition, the tack | development temperature in this specification intends the temperature which develops the tack | tuck of 0.1N or more, when it measures by the probe tack method.

If the Tg of the acrylic resin is less than 50 ° C., the effect of increasing the tack development temperature of the adhesive film cannot be sufficiently exhibited, and tack may be developed at a temperature of 40 ° C. or less. On the other hand, if the Tg of the acrylic resin exceeds 90 ° C., the tack development temperature of the adhesive film becomes extremely high, and it is necessary to change the conditions for thermocompression bonding with a press. Moreover, compatibility with other components is lowered, and workability in producing an adhesive film is deteriorated. Moreover, an adhesive film is inferior to a softness | flexibility.
As the component (A), it is more preferable to use an acrylic resin having a Tg of 50 to 70 ° C.

The acrylic resin used as the component (A) is not particularly limited as long as Tg is 50 to 90 ° C., but a methyl methacrylate / butyl acrylate copolymer containing a methyl methacrylate component and a butyl acrylate component. Is preferred. In addition, when these components constituting the copolymer are used alone, the intended effect cannot be exhibited. The methyl methacrylate component alone is inferior in flexibility, and the butyl acrylate component alone exhibits tack at room temperature regardless of Tg.
Among them, a methyl methacrylate / butyl acrylate copolymer containing a methyl methacrylate component (x) and a butyl acrylate component (y) in a ratio of x / y = 8/2 to 6/4 is tacky. It is preferable because an adhesive film with a controlled expression temperature can be obtained relatively easily and the film is excellent in flexibility. When x / y> 8/2, the film tends to be inferior in flexibility, and when x / y <6/4, it becomes difficult to control the tack development temperature of the film with the Tg of the acrylic resin.

In addition to x / y satisfying the above range, the methyl methacrylate / butyl acrylate copolymer has a mass average molecular weight (Mw) of 400,000 to 600,000. It is preferable from the viewpoints of compatibility and maintaining interlayer insulation of the film.
When Mw is less than 400,000, there is a possibility that the interlayer insulation of the film cannot be maintained. On the other hand, when Mw is more than 600,000, the compatibility with other components is lowered, and thus the production of the film may be difficult.

The adhesive film of this invention contains 40-70 mass% of components (A), ie, the acrylic resin whose Tg is 50-90 degreeC. When the content of the component (A) is less than 40%, problems such as deterioration of the film shape retention rate occur. In this specification, when it says the shape retention of a film, the retention of film thickness is intended. A film having a substantially constant thickness regardless of the thickness of any part of the film, that is, a film having little blur in the measured value of the film thickness is said to be excellent in film shape retention.
On the other hand, when the content of the component (A) exceeds 70%, problems such as inferior flexibility of the film arise.

(B) Copolymer of acrylonitrile and elastomer component Since the adhesive film of the present invention uses an acrylic resin having a high Tg of 50 to 90 ° C., the adhesive film generally tends to be inferior in flexibility. In this invention, the softness | flexibility of an adhesive film is improving by containing the copolymer of an acrylonitrile and an elastomer component as (B) component.
As the elastomer component used as the component (B), a butadiene component is preferable for the purpose of improving the shear strength.

As described above, the component (B) is preferably an acrylonitrile-butadiene copolymer. In the acrylonitrile-butadiene copolymer, the content ratio of the acrylonitrile component (m) and the butadiene component (n) is m / n = 1/9 to 9/1. It is preferable for maintaining the balance.
When m / n does not satisfy the above range, there is a possibility that the shear strength of the film is lowered or the stability over time is lowered.
m / n = 1/9 to 9/1 is more preferable, 2/8 to 8/2 is further preferable, and 3/7 to 7/3 is particularly preferable.

  The copolymer constituting the component (B) may contain other components in addition to the acrylonitrile and butadiene components. In this case, examples of other components that can be included include an acrylic acid component, a methacrylic acid component, an ethacrylic acid component, a crotonic acid component, a maleic acid component, a phthalic acid component, an itaconic acid component, and mixtures thereof. Among these, in the case of a methacrylic acid component, a copolymer containing the component is preferable because of excellent compatibility with other components.

  (B) When the copolymer which comprises a component contains other components other than an acrylonitrile and a butadiene component, the content rate of an acrylonitrile and a butadiene component and another component is not specifically limited. However, when the content ratio of acrylonitrile and the butadiene component is the most preferable m / n = 1/1, the content ratios of the other components (o) are also preferably the same. That is, it is preferable that m / n / o = 1/1/1.

The copolymer constituting the component (B) preferably has an Mw of 200,000 to 1,000,0000 because it is excellent in the compatibility with other components, the balance of film adhesion and flexibility.
When Mw is less than 200,000, the film may be inferior in adhesive strength and flexibility. On the other hand, when Mw exceeds 1,000,000, the compatibility with other components may be inferior.

  The adhesive film of this invention contains 10-30 mass% of components (B). If the content of component (B) is less than 10%, the film is inferior in flexibility. On the other hand, if the content of the component (B) exceeds 30%, it becomes difficult to control the tack development temperature.

(C) Mixture of solid epoxy resin and liquid epoxy resin The adhesive film of the present invention contains a mixture of a solid epoxy resin and a liquid epoxy resin as an epoxy resin component.
When it contains only a solid epoxy resin, since it is inferior in compatibility with other components, there exists a possibility that the composition of the adhesive film obtained may not become uniform. If the composition of the adhesive film is non-uniform, there will be a difference in adhesiveness depending on the part of the film, which may result in failure in the adhesion test.
On the other hand, when only liquid epoxy resin is contained, the corners of the adhesive film may be crushed when thermocompression bonding is performed by pressing (when the press plate is larger than the film. On the other hand, compared to the film) If the press plate is small, the corners of the film in contact with the press plate may be crushed. Hereinafter, in this specification, these phenomena are collectively referred to as “corner portions are crushed during thermocompression bonding by a press. "" In this case, since the metal members to be bonded are in direct contact with each other, the intended insulation cannot be exhibited.

  The solid epoxy resin and liquid epoxy resin used as the component (C) are not particularly limited. However, as the solid epoxy resin, the bisphenol A type solid resin is not crushed at the time of thermocompression bonding by a press, and the tack is increased. It is preferable because it contributes to the above.

The bisphenol A-type solid resin preferably has an Mw of 1,500 to 2,500 because it is easy to adjust the curing temperature of the film.
When Mw is less than 1,500, the curing temperature of the film becomes low, and it may be difficult to make the tack development temperature within a desired range. On the other hand, when Mw exceeds 2,500, the adhesion temperature of the film becomes high, and it may be difficult to make the tack development temperature within a desired range.

Further, as the liquid epoxy resin, a liquid bisphenol F (BPF) type epoxy resin is preferable because of excellent compatibility with other components.
The liquid bisphenol F type epoxy resin preferably has an Mw of 100 to 500 from the viewpoint of compatibility with other components and prevention of sublimation during thermocompression bonding by pressing. When Mw is less than 100, the liquid epoxy resin may sublime at the time of thermocompression bonding by a press. On the other hand, when Mw exceeds 500, the compatibility with other components may be reduced, and the composition of the resulting adhesive film may not be uniform.

(C) When using bisphenol A type solid resin (a), liquid bisphenol F type epoxy resin (b), and a mixture as a component, both content rate is a / b = 1 / 9-9 / 1. It is preferable because the corners are not crushed during thermocompression bonding by a press, and the balance between properties such as compatibility with other components and film adhesion is excellent.
When a / b does not satisfy the above range, a film having an excellent balance of the above characteristics may not be obtained.
It is more preferable that a / b = 4/6 to 6/4, and particularly preferably 1/1.

The adhesive film of this invention contains 5-40 mass% of components (C). If the content of component (C) is less than 5%, sufficient adhesive strength cannot be obtained. On the other hand, if the content of the component (C) is more than 40%, it becomes difficult to adjust the compatibility with other components and the tack development temperature.
As for content of a component (C), it is more preferable that it is 10-40 mass%.

(D) Epoxy curing agent The epoxy curing agent can be widely selected from those used as curing agents for epoxy resins. For example, curing agents such as imidazole curing agents, amine curing agents, phenol curing agents, thiol curing agents, and acid anhydrides can be used. Of these, imidazole curing agents are preferred for reasons such as curing reaction control by heating and storage stability at room temperature.
Examples of imidazole curing agents that can be used include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, and the like.
As the amine curing agent, for example, diethylenetriamine, triethylenetetramine, metaxylylenediamine, isophoronediamine, 1,3-bisaminomethylcyclohexane, diaminodiphenylmethane, metaphenylenediamine, diaminodiphenylsulfone, dicyandiamide and the like can be used.
As the phenolic curing agent, phenol novolac resin, cresol novolac resin, naphthol modified phenol resin, dicyclopentadiene modified phenol resin, p-xylene modified phenol resin, and the like can be used.
As the thiol curing agent, aliphatic polythiols, aromatic polythiols, thiol-modified reactive silicone oils, and the like can be used.
Acid anhydrides include methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, alkylated tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyl hymic anhydride, dodecenyl succinic anhydride, methyl nadic anhydride Etc. can be used.

The adhesive film of this invention contains 0.1-5 mass% of components (D). When the content of component (D) is less than 0.1%, problems such as insufficient curing occur. On the other hand, when the content of the component (D) exceeds 5%, problems such as precipitation of the curing agent in the film occur.
As for content of a component (D), it is more preferable that it is 0.2-1.5 mass%, and it is further more preferable that it is 0.5-0.8 mass%.

The adhesive film of the present invention may contain components other than the above components (A) to (D). Examples of other components that may be included include an epoxy curing accelerator, a coupling agent, an inorganic filler, a rubber filler, and organic beads.
As the epoxy curing accelerator, for example, an organic acid, a strong organic base, a tertiary amine or the like can be used.

  As for the adhesive film of this invention, it is more preferable that thickness is 10-100 micrometers. When the thickness of the adhesive film is more than 100 μm, the thickness is too large, so that the flexibility of the film is lowered and the handleability is deteriorated. In addition, bubbles are likely to remain in the produced film due to bubble entrainment or generation of bubbles in the subsequent process due to the solvent remaining. Moreover, it is difficult to produce a film having a uniform composition. On the other hand, when the thickness of the film is less than 10 μm, the thickness is too small, so that the film may be torn during bonding or handling. In addition, since it becomes easy to be charged with static electricity, the handling property is deteriorated.

The adhesive film of the present invention is composed of components (A) to (D) (when the adhesive film contains components other than components (A) to (D), the other components are in a desired content ratio. After applying the solution dissolved or dispersed in the substrate, the substrate is heated to remove the solvent, and then removed from the substrate.
Examples of the solvent used in this case include methyl ethyl ketone, acetone, methyl isobutyl ketone, toluene, butyl cellosolve, 2-ethoxyethanol, methanol, ethanol, isopropyl alcohol and the like having a relatively low boiling point.

  As the base material, a base material that does not have the same tendency of hydrophobicity or hydrophilicity as the acrylic resin in the adhesive film is used. As a base material that does not have the same hydrophobicity or hydrophilicity as an acrylic resin, a polymer film material or an inorganic material base material coated with polyimide, slide glass, polypropylene, polyethylene terephthalate, etc. with a water-repellent component or a hydrophobic component is preferably used. It is done.

  The adhesive film of the present invention before use is stored in a state of being sandwiched between protective films in order to prevent foreign matter from adhering. As a protective film, what was described as a base material can be used.

The adhesive film of the present invention has characteristics suitable as an intermetal insulating holding adhesive film.
As described above, the adhesive film of the present invention does not develop tack at a temperature around 40 ° C., but develops tack at a temperature of 50 ° C. or higher. Therefore, when the adhesive film is placed on the metal member, it is easy to remove the bubbles even if there are bubbles between them. Therefore, by performing thermocompression bonding with a press while air bubbles remain between the metal member and the adhesive film, the possibility of peeling on the adhesive surface or misalignment of the bonded metal member is eliminated. Is done. Moreover, it is easy to isolate the adhesive film before use from the protective film. In addition, since the tack development temperature of the adhesive film does not become extremely high, it is not necessary to change the conditions for thermocompression bonding with a press.

The adhesive film of this invention hardens | cures at the temperature of 150 degreeC or more, and adhesive force increases.
When bonding metal members to each other using the adhesive film of the present invention, after placing the adhesive film of the present invention on the adherend surface of one metal member, the adherend surface of the other metal member is the adhesive film. What is necessary is just to perform the thermocompression bonding by a press for 60 to 90 minutes at predetermined temperature and predetermined time, specifically, 150 degreeC in the state mounted in contact with the exposed surface. The adhesive film of the present invention is cured by heating when thermocompression bonded by a press. Hereinafter, in the present specification, the characteristics of the adhesive film of the present invention after bonding are described as the characteristics of the adhesive film after heat curing.

  The adhesive film of the present invention after heat curing has sufficient adhesive strength. Specifically, the peel strength measured according to JIS C5416 is 10 N / cm or more, preferably 15 N / cm or more, more preferably 20 N / cm or more, and further preferably 30 N / cm or more.

  The adhesive film of the present invention after heat curing is excellent in insulation. Specifically, the adhesive film of the present invention after heat curing preferably has a dielectric breakdown voltage of AC 1.0 kV / 20 μm or more, more preferably AC 1.5 kV / 20 μm or more, and AC 2.0 kV / 20 μm. More preferably, it is the above.

  The adhesive film of this invention is excellent in a softness | flexibility, and has sufficient bending strength. Specifically, the folding endurance when the folding strength test (JIS P8115) using the MIT testing machine is performed is preferably 10 times or more, more preferably 200 times or more, and 1,000 times. More preferably, it is the above.

  The adhesive film of the present invention after heat curing has a sufficient surface hardness. Specifically, it has a surface hardness of 3B or more in pencil hardness.

As will be described later, when the adhesive film of the present invention is used for the purpose of forming electrical wiring on a metal substrate, the adhesive film of the present invention after heat curing can be applied with a solder resist on the surface thereof. Is required. When the adhesive film of the present invention is used for such applications, it is required to have sufficient wettability with respect to the solder resist after heat curing.
Moreover, when using the adhesive film of this invention for such a use, it is calculated | required to have the tolerance to the chemical | medical solution for an etching after heat-hardening.

  The adhesive film of the present invention can be used for bonding a wide variety of metal members. The material of the metal member bonded using the adhesive film of the present invention is not particularly limited, and examples thereof include steel, stainless steel, aluminum, and copper. Moreover, the metal member bonded using the adhesive film of the present invention may not be a metal as a whole. A specific example of such a metal member is an FR4 substrate having a copper foil.

As an example of a suitable application of the adhesive film of the present invention, there is a case where a copper foil is bonded for the purpose of forming electric wiring on a base made of carbon steel for mechanical structure.
When forming an electrical wiring on a base, first, the adhesive film of the present invention is placed on the adherend surface of the base. Even if air bubbles are present between the two, the adhesive film of the present invention does not exhibit tack at a temperature of 40 ° C. or lower, so that it is easy to remove the air bubbles. Next, copper foil is mounted on an adhesive film. At this time, it is preferable to place the copper foil so that the roughened surface is in contact with the adhesive film. In this state, thermocompression bonding with a press may be performed at a predetermined temperature and for a predetermined time, specifically, at 150 ° C. for 60 to 90 minutes. Thereby, the composite metal member by which the base made from the carbon steel for machine structures and copper foil were adhere | attached through the adhesive film of this invention is obtained.
In order to form the electric wiring on the base, the copper foil may be patterned so as to have a predetermined electric wiring shape by using a photolithography process. Then, a solder resist is apply | coated on the adhesive film exposed by the copper foil and the photolithographic process as needed.

  The composite metal member of the present invention broadly includes those in which two metal members are bonded via the adhesive film of the present invention, and the shape, size and material of the metal member are not particularly limited. The two metal members may be made of the same material or different materials. The material of the metal member is as described above. Other than those mentioned above, combinations such as aluminum and aluminum alloy, aluminum or aluminum alloy and copper, aluminum or aluminum alloy and stainless steel, aluminum or aluminum alloy and steel, steel and stainless steel, copper and steel, stainless steel and steel, etc. Illustrated.

Hereinafter, the present invention will be described more specifically with reference to examples.
(Examples 1-6)
After applying a solution in which components (A) to (D) are dissolved or dispersed in a solvent so as to have a blending ratio (parts by mass) shown in Table 1, the substrate (PET film subjected to a release treatment) is applied. The substrate was heated to remove the solvent, and then removed from the substrate to obtain an adhesive film.
In addition, Examples 1-5 change Tg of the acrylic resin which is a component (A). The acrylic resins used in each example are as follows.
Example 1: Methyl methacrylate / butyl acrylate copolymer (ratio = 1/9, Tg: −30 ° C., Mw: 900,000 ± 100,000)
Example 2: Methyl methacrylate / butyl acrylate copolymer (ratio = 3/7, Tg: 20 ° C., Mw: 800,000 ± 100,000)
Example 3: Methyl methacrylate / butyl acrylate copolymer (ratio = 4/6, Tg: 30 ° C., Mw: 700,000 ± 100,000)
Example 4: Methyl methacrylate / butyl acrylate copolymer (ratio = 5/5, Tg: 40 ° C., Mw: 600,000 ± 100,000)
Example 5: Methyl methacrylate / butyl acrylate copolymer (ratio = 7/3, Tg: 50 ° C., Mw: 500,000 ± 100,000)
Example 6: Methyl methacrylate / butyl acrylate copolymer (ratio = 7/3, Tg: 70 ° C.
(Mw: 500,000 ± 100,000)

Components (B) and (C) are as follows.
Component (B): acrylonitrile / butadiene / methacrylic acid copolymer (ratio: 1/1/1, Mw: 500,000)
Component (C): bisphenol A type solid epoxy resin (Mw: 2000), liquid bisphenol F (BPF) type epoxy resin (Mw: 320)
The film thickness of the obtained adhesive film was measured using a contact-type film thickness meter.

The following physical property evaluation was implemented with respect to the obtained adhesive film.
The compatibility was evaluated according to the following criteria.
○: In a standard state (temperature: 25 ° C., atmospheric pressure: 1 bar), the mixture is stirred until it is uniform, and then it is in a uniform state when visually observed after standing.
X: In a standard state (temperature: 25 ° C., atmospheric pressure: 1 bar), the mixture is stirred until it is uniform, and then, after standing still, it is in a non-uniform state.
Film formation was evaluated according to the following criteria.
○: A uniform film is obtained.
(Triangle | delta): Since the mixture could not be made uniform, the mottled pattern was generated at the time of film formation.
X: Film cannot be formed.
The surface hardness pencil hardness is the hardness of the film surface after being cured by heating at 150 ° C. for 60 minutes.
Bending test MIT test was carried out according to JIS P8115. The evaluation criteria are as follows.
○: It was possible to bend twice or more.
X: Fracture occurred by bending once.
Post-adhesion interlayer insulation test: As shown in FIG. 1, the post-adhesion interlayer insulation test is performed by using a carbon steel base 30 (thickness 10 mm) and a copper foil through an adhesive film 10 (thickness 80 μm). 20 (thickness 0.018 to 0.035 mm) and thermocompression bonding (150 ° C., 60 minutes, 1 MPa) with a press to form a laminate, and the interlayer insulation of the laminate was evaluated using a tester 40. When the scale of the tester was OL (overload), it was determined to be OK, and the others were determined to be NG.
Defoaming property: The defoaming property was confirmed by visual observation of the surface state from the copper foil side after heating the laminate prepared in the above procedure at 150 ° C. for 8 hours in an oven. When air bubbles remain on the adhesive surface (between the adhesive film and the copper foil, or between the adhesive film and the base), a convex portion is formed on the surface of the copper foil. The case where such a convex part was not recognized was set to OK, and the case where it was recognized was set to NG.
Tack: Measured using a probe tack tester.
The results are shown in Table 1.

表１から明らかなように、アクリル樹脂のＴｇが５０℃以上の例５〜６では、４０℃で実質的にタックを発現しなかったのに対して、アクリル樹脂のＴｇが４０℃以下の例１〜４では、４０℃でタックを発現した。また、これら例１〜４はいずれも加熱後の積層体において、接着面に残留する気泡による凸部が銅箔表面に認められた。
例５の接着フィルムについては、ピール強度、引張強度、引張伸び、引張弾性率の測定も以下の点で実施した。
ピール強度：接着後層間絶縁試験に記載した積層体について、幅１０ｍｍの銅箔を１８０°で引き剥がす際の強度を測定した。結果は３０Ｎ／ｃｍであった。
引張強度：１５０℃で６０分間加熱して硬化させた接着フィルムの引張強度及び引張伸びをＪＩＳ Ｃ５０１６にしたがって測定した。その結果、引張強度は３８．０ＭＰａであり、引張伸びは７９．４ｍｍであった。
引張弾性率：未硬化の接着フィルムと１５０℃で６０分間加熱して硬化させた接着フィルムの引張弾性率をＪＩＳ Ｃ２３１８にしたがって測定した。その結果、未硬化の接着フィルムの引張弾性率は５３９ＧＰａであり、加熱硬化後の接着フィルムの引張弾性率は８２８ＧＰａであった。

As is apparent from Table 1, in Examples 5 to 6 where the Tg of the acrylic resin was 50 ° C. or higher, tack was not substantially exhibited at 40 ° C., whereas the Tg of the acrylic resin was 40 ° C. or lower. In 1-4, tack was expressed at 40 ° C. Moreover, as for these Examples 1-4, the convex part by the bubble which remain | survives on the adhesion surface was recognized by the copper foil surface in the laminated body after a heating.
For the adhesive film of Example 5, measurements of peel strength, tensile strength, tensile elongation, and tensile elastic modulus were also performed as follows.
Peel strength: For the laminate described in the interlayer insulation test after adhesion, the strength when peeling a copper foil having a width of 10 mm at 180 ° was measured. The result was 30 N / cm.
Tensile strength: Tensile strength and tensile elongation of an adhesive film cured by heating at 150 ° C. for 60 minutes were measured according to JIS C5016. As a result, the tensile strength was 38.0 MPa and the tensile elongation was 79.4 mm.
Tensile elastic modulus: The tensile elastic modulus of an uncured adhesive film and an adhesive film cured by heating at 150 ° C. for 60 minutes was measured according to JIS C2318. As a result, the tensile modulus of the uncured adhesive film was 539 GPa, and the tensile modulus of the adhesive film after heat curing was 828 GPa.

成分（Ｂ）を含有しなかった例７の接着フィルムは、柔軟性に劣り、ＭＩＴ試験の際、１回の折り曲げでフィルムが破断した。成分（Ｃ）のうち液状エポキシ樹脂を含有しなかった例８は、フィルム製造時の相溶性が低く、各成分を均一に混合することができなかったため、得られたフィルムにまだら模様が発生した。このため、例８についてはＭＩＴ試験及び接着後層間絶縁試験は実施しなかった。成分（Ｃ）のうち固形エポキシ樹脂を含有しなかった例９のフィルムは、図２に示すようにプレスに熱圧着した際に、接着フィルム１０の角がつぶれてしまい、銅箔２０と基台３０とが直接接する個所（図中破線で示した個所）が生じてしまい、テスター４０の目盛りがＯＬとならなかった。 (Examples 7 to 9)
The adhesive film was created so that it might become a mixture ratio shown in Table 2, and the physical property of the adhesive film was evaluated. Example 7 was an example in which component (B) was not blended, Example 8 was an example in which liquid epoxy resin was not blended among components (C), and Example 9 was a solid epoxy resin in component (C). This is an example of not blending. In addition, Example 5 is the same as what was used as component (A)-(D).
The results are shown in Table 2.

The adhesive film of Example 7, which did not contain the component (B), was inferior in flexibility, and the film was broken by one folding during the MIT test. In Example 8, which did not contain a liquid epoxy resin among the components (C), the compatibility at the time of film production was low, and each component could not be mixed uniformly. Therefore, a mottled pattern was generated on the obtained film. . For this reason, in Example 8, the MIT test and the post-bonding interlayer insulation test were not performed. When the film of Example 9 which did not contain a solid epoxy resin among components (C) was thermocompression bonded to a press as shown in FIG. 2, the corners of the adhesive film 10 were crushed, and the copper foil 20 and the base A portion (a portion indicated by a broken line in the figure) in direct contact with 30 was generated, and the scale of the tester 40 did not become OL.

いずれの例も本発明の接着フィルムに要求される特性を満たしていなかった。 (Examples 10 to 15)
The adhesive film was created so that it might become a mixture ratio shown in Table 3, and the physical property of the adhesive film was evaluated. Example 10 is an example which mix | blended only the solid epoxy resin among a component (B) and a component (C). Example 11 is an example in which an epoxy group-modified acrylic resin was blended as the component (A) and no liquid epoxy resin was blended among the components (B) and (C). Example 12 is an example in which phenol was added to the components of Example 10. Example 13 is an example which did not mix | blend a component (A). Example 14 is an example in which an epoxy group-modified acrylic resin was blended as the component (A). Example 15 is an example (component (B) is a main component) in which the blending amounts of components (A) and (B) did not satisfy the scope of the present invention.
The results are shown in Table 3.

None of the examples satisfied the properties required for the adhesive film of the present invention.

例５と同様に優れた物性を示した。成分（Ｃ）の配合割合を高くすることにより、表面硬度（鉛筆硬度）が上昇する傾向が見られた。 (Examples 16 to 17)
About the combination of Example 5, the adhesive film was created as a mixture ratio shown in Table 4, and the physical property of the adhesive film was evaluated.

As in Example 5, excellent physical properties were exhibited. The tendency for surface hardness (pencil hardness) to increase by increasing the blending ratio of component (C) was observed.

FIG. 1 is a schematic diagram for explaining an interlayer insulation test. FIG. 2 is a schematic view showing the state of an interlayer insulation test of the adhesive film of Example 8.

Explanation of symbols

10 Adhesive film 20 Copper foil 30 Base 40 Tester

Claims (5)

An adhesive film containing the following components (A) to (D).
(A) Acrylic resin having a glass transition point (Tg) of 50 to 90 ° C. 40 to 70% by mass
(B) Copolymer of acrylonitrile and elastomer component 10 to 30% by mass
(C) Mixture of solid epoxy resin and liquid epoxy resin 5 to 40% by mass
(D) Epoxy curing agent 0.1 to 5% by mass  The adhesive film according to claim 1, wherein tack is not developed at a temperature of 40 ° C. or lower, and tack is developed at a temperature of 50 ° C. or higher. The component (A) contains a methyl methacrylate component (x) and a butyl acrylate component (y) in a ratio of x / y = 8/2 to 6/4, and the mass average molecular weight (Mw) is A methyl methacrylate / butyl acrylate copolymer of 400,000 to 600,000,
The component (B) is an acrylonitrile-butadiene copolymer containing the acrylonitrile component (m) and the butadiene component (n) in a ratio of m / n = 1/9 to 9/1.
The component (C) is a mixture containing bisphenol A type solid resin (a) and liquid bisphenol F type epoxy resin (b) at a ratio of a / b = 1/9 to 9/1.
The adhesive film of Claim 1 or 2 whose said component (D) is an imidazole series hardening | curing agent. The component (A) contains a methyl methacrylate component (x) and a butyl acrylate component (y) in a ratio of x / y = 8/2 to 6/4, and the mass average molecular weight (Mw) is A methyl methacrylate / butyl acrylate copolymer of 400,000 to 600,000,
The component (B) contains an acrylonitrile component, a butadiene component and a methacrylic acid component, and the content ratio of the acrylonitrile component (m) and the butadiene component (n) is m / n = 1/9 to 9 /. 1, an acrylonitrile-butadiene-methacrylic acid copolymer,
The component (C) is a mixture containing bisphenol A type solid resin (a) and liquid bisphenol F type epoxy resin (b) at a ratio of a / b = 1/9 to 9/1.
The adhesive film of Claim 1 or 2 whose said component (D) is an imidazole series hardening | curing agent.   A composite metal member in which two metal members are bonded via the adhesive film according to any one of claims 1 to 4.

Images