Adhesive composition

Abstract

The present application provides an adhesive composition having good electrical properties (dielectric properties) capable of coping with 5G, and also showing good adhesion to low-dielectric substrate films having poor adhesion, forming a low-dielectric adhesive layer having both heat resistance and chemical resistance (solvent resistance). The adhesive composition contains a styrene-based elastomer and an epoxy-modified resin having a structure represented by the following formula (1).(R 1 , R 2 , R 3 , and R 4 each independently represent hydrogen or an organic group. Among them, at least one of R 1 and R 2 is an organic group, and at least one of R 3 and R 4 is an organic group).

Description

Technical Field

[0001] This invention relates to an adhesive composition. More specifically, this invention relates to an adhesive composition suitable for bonding electronic components and the like. Background Technology

[0002] With the miniaturization and weight reduction of electronic devices, the bonding applications of electronic components have diversified, leading to an increased demand for laminates with adhesive layers.

[0003] Furthermore, in flexible printed circuit boards (hereinafter also known as FPCs), which are electronic components, high-speed processing of large amounts of data is required, necessitating solutions for high frequencies. The increasing frequency of FPCs requires lower dielectric constants for the constituent components, leading to the development of low-dielectric substrate films and low-dielectric adhesives. In particular, for the efficient transmission of signals using frequencies in the 3.5GHz and 28GHz bands used in fifth-generation mobile communication systems (hereinafter also known as 5G), the importance of low-loss substrate films and adhesives in the 28GHz millimeter-wave band is increasing.

[0004] However, due to the low polarity of the main agent molecules, low dielectric adhesives are difficult to achieve good adhesion to the substrate film and other components associated with electronic components. In addition, low dielectric substrate films sometimes also have poor adhesion to adhesives, requiring improved adhesion.

[0005] Therefore, in order to have good electrical properties (low relative permittivity and low dielectric loss tangent) and satisfy high adhesion, it is proposed to use an adhesive composition containing a carboxyl-containing styrene elastomer (A) and an epoxy resin (B), and a laminate comprising an adhesive layer containing the adhesive composition and a substrate film (for example, see Patent Document 1).

[0006] Prior art literature

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2016 / 017473 Summary of the Invention

[0009] (The problem the invention aims to solve)

[0010] However, low-dielectric adhesives have fewer reactive groups in their main molecule, resulting in poor reactivity with the curing agent. Furthermore, if epoxy resin is used as the curing agent, there is a tendency for the dielectric loss tangent to increase. Due to these factors, it is extremely difficult to achieve a balance between curing properties that affect the adhesive composition, heat resistance, chemical resistance (solvent resistance), and low dielectric properties.

[0011] Therefore, the object of the present invention is to provide an adhesive composition having good electrical properties (dielectric properties) capable of coping with 5G and exhibiting good adhesion to low-dielectric substrate films with poor adhesion, forming a low-dielectric adhesive layer that is both heat-resistant and chemically resistant (solvent-resistant).

[0012] (Technical solution used to solve the problem)

[0013] In order to solve the above-mentioned problems, the inventors conducted repeated and in-depth research and found that an adhesive composition containing a styrene-based elastomer and a specific epoxy-modified resin can solve the above-mentioned problems, thereby completing the present invention.

[0014] The present invention includes the following methods.

[0015] [1] An adhesive composition comprising a styrene-based elastomer and an epoxy-modified resin having a structure represented by the following formula (1).

[0016]

[0017] (R 1 R 2 R 3 and R 4 Each can independently represent either hydrogen or an organic group. Among them, R... 1 and R 2 At least one of them is an organic group, and R 3 and R 4 At least one of them is an organic group.

[0018] [2] According to the adhesive composition described in [1], wherein the styrene elastomer is a styrene elastomer containing a carboxyl group.

[0019] [3] According to the adhesive composition described in [1], wherein the styrene elastomer is a styrene elastomer containing amino groups.

[0020] [4] The adhesive composition according to any one of [1] to [3], wherein the content of the epoxy modified resin is 1 to 50 parts by weight relative to 100 parts by weight of the adhesive composition.

[0021] [5] The adhesive composition according to any one of [1] to [4], wherein the epoxy equivalent of the epoxy modified resin is 200 g / eq. or more and 20000 g / eq. or less.

[0022] [6] The adhesive composition according to any one of [1] to [5], wherein the epoxy modified resin has the structure represented by the following formula (2).

[0023]

[0024] (R 5 and R 6 Each of the above-mentioned structures (2) independently represents an alkyl group with 10 or fewer carbon atoms. In the case where multiple structures represented by these formulas exist in the epoxy modified resin, the R in each formula (2) represents... 5 Each can be the same or different, and R in each equation (2) 6 They can be the same or different. * indicates a bonding group.

[0025] [7] The adhesive composition according to any one of [1] to [6], wherein the epoxy modified resin contains unsaturated bonds other than aromatic rings.

[0026] [8] According to the adhesive composition described in [7], wherein the epoxy modified resin has a structure represented by the following formula (3).

[0027]

[0028] (R 7 and R 8 Each of the above-mentioned structures (3) independently represents an alkyl group with 10 or fewer carbon atoms. In the case where multiple structures represented by these formulas exist in the epoxy modified resin, the R in each formula (3) represents... 7 Each can be the same or different, and R in each equation (3) 8 They can be the same or different. * indicates a bonding group.

[0029] [9] The adhesive composition according to any one of [1] to [8], wherein the epoxy modified resin has at least one of the structures represented by the following formula (4) and the following formula (5).

[0030]

[0031] (R 9 and R 10 Each of the above-mentioned structures (4) independently represents an alkyl group with 10 or fewer carbon atoms. In the case where multiple structures represented by these formulas exist in the epoxy modified resin, the R in each formula (4) represents... 9 Each can be the same or different, and R in each equation (4) 10 They can be the same or different. * indicates a bonding group.

[0032]

[0033] (R 11 and R 12Each independently represents a hydrogen atom or an alkyl group having 10 or fewer carbon atoms. In the case where multiple structures represented by the above formula (5) exist in the aforementioned epoxy modified resin, R in each formula (5) 11 Each can be the same or different, and R in each equation (5) 12 They can be the same or different. * indicates a bonding group.

[0034]

[10] According to the adhesive composition described in [6], wherein R in the above formula (2) is... 5 and R 6 Both are hydrogen.

[0035]

[11] According to the adhesive composition described in [8], wherein R in the above formula (3) 7 and R 8 Both are hydrogen.

[0036]

[12] According to the adhesive composition described in [9], wherein R in the above formula (4) 9 and R 10 All are hydrogen, or R in equation (5) above 11 and R 12 Both are hydrogen.

[0037]

[13] The adhesive composition according to any one of [1] to

[12] , wherein the epoxy modified resin is an epoxy modified elastomer obtained by modifying an elastomer containing unsaturated bonds with a peroxide.

[0038]

[14] The adhesive composition according to any one of [1] to

[13] , wherein the epoxy modified resin is a styrene elastomer.

[0039]

[15] The adhesive composition according to any one of [1] to

[14] , wherein the weight-average molecular weight (Mw) of the epoxy modified resin is 30,000 or more and 200,000 or less.

[0040]

[16] An adhesive composition according to any one of [1] to

[15] , wherein the adhesive composition contains a filler.

[0041]

[17] An adhesive composition according to any one of [1] to

[16] , wherein the adhesive composition contains a free radical polymerization initiator.

[0042]

[18] An adhesive composition according to any one of [1] to

[17] , wherein the adhesive composition contains an organic peroxide.

[0043]

[19] An adhesive layer, wherein it is an adhesive layer formed by curing an adhesive composition described in any one of [1] to

[18] , wherein the relative permittivity of the adhesive layer measured at a frequency of 28 GHz is 3 or less, and the dielectric loss tangent is 0.004 or less.

[0044]

[20] A laminate having a substrate film and an adhesive layer comprising an adhesive composition described in any one of [1] to

[18] or an adhesive layer described in

[19] .

[0045]

[21] According to the laminate described in

[20] , wherein the substrate film contains polyetheretherketone (PEEK) resin.

[0046]

[22] A cover film with an adhesive layer comprising the laminate described in

[20] or

[21] .

[0047]

[23] A copper-clad laminate comprising the laminate described in

[20] or

[21] .

[0048]

[24] A printed circuit board comprising the laminate described in

[20] or

[21] .

[0049]

[25] A shielding film comprising the laminate described in

[20] or

[21] .

[0050]

[26] A printed circuit board with a shielding film, comprising the laminate described in

[20] or

[21] .

[0051] (Invention Effects)

[0052] According to the present invention, an adhesive composition is provided that has good electrical properties (dielectric properties) capable of coping with 5G and also exhibits good adhesion to low-dielectric substrate films with poor adhesion, forming a low-dielectric adhesive layer that is both heat-resistant and chemical-resistant (solvent-resistant). Detailed Implementation

[0053] Hereinafter, the adhesive composition of the present invention, the laminate containing the adhesive layer containing the adhesive composition, and the electronic components related to the laminate containing the laminate will be described in detail. The description of the constituent elements described below is an example of one embodiment of the present invention and is not limited thereto.

[0054] (Adhesive composition)

[0055] The adhesive composition of the present invention contains a styrene-based elastomer and an epoxy-modified resin having the structure represented by the following formula (1).

[0056]

[0057] (R 1 R 2 R 3 and R 4 Each can independently represent either hydrogen or an organic group. Among them, R... 1 and R 2 At least one of them is an organic group, and R 3 and R 4 At least one of them is an organic group.

[0058] The adhesive composition of the present invention may also contain other components as needed.

[0059] The adhesive compositions of the present invention, which contain styrene-based elastomers and epoxy-modified resins having the structure represented by the above formula (1), exhibit good adhesion even as low dielectric adhesive compositions, and are also excellent adhesive compositions with heat resistance and chemical (solvent) resistance.

[0060] <Styrene-based elastomers>

[0061] Styrene-based elastomers are copolymers and their hydrogenates mainly composed of block and random structures of conjugated diene compounds and aromatic vinyl compounds.

[0062] Having fewer highly polar bonding groups within the molecule imparts excellent electrical properties (dielectric properties) to the composition. Furthermore, compared to other types of elastomers, the molecular weight is easier to control, resulting in stable adhesive composition properties and improved manufacturing processes.

[0063] Examples of aromatic vinyl compounds include styrene, tert-butylstyrene, α-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-diethyl-p-aminoethylstyrene, and vinyltoluene. Examples of conjugated diene compounds include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene.

[0064] Specific examples of styrene-based elastomers include styrene-butadiene block copolymers, styrene-ethylene-propylene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylene-butene-styrene block copolymers, and styrene-ethylene-propylene-styrene block copolymers.

[0065] The styrene-based elastomer can be either modified or unmodified, without particular limitation, and can be selected according to the purpose. As the component imparting adhesion after curing, modified styrene-based elastomers such as those containing carboxyl groups or amino groups, as described below, are preferred. As the component for adjusting the adhesion based on lamination and the elastic modulus at various temperatures, unmodified styrene-based elastomers are preferred.

[0066] Styrene-based elastomers can be used alone or in combination with two or more. In particular, by using modified styrene-based elastomers with good adhesion to the surface of the adherend and unmodified styrene-based elastomers with adjustable elastic modulus at various temperatures, it is possible to achieve high adhesion and control of flowability.

[0067] Among the aforementioned copolymers, from the viewpoint of being able to impart adhesive properties and electrical properties (dielectric properties) to the adhesive composition, and that the molecular structure is relatively easy to control and the properties of the adhesive composition are easily adjusted, styrene-ethylene-butene-styrene block copolymers and styrene-ethylene-propylene-styrene block copolymers are preferred. Furthermore, the mass ratio of styrene to ethylene-butene in the styrene-ethylene-butene-styrene block copolymer and the mass ratio of styrene to ethylene-propylene in the styrene-ethylene-propylene-styrene block copolymer are preferably 10 / 90 to 50 / 50, more preferably 20 / 80 to 40 / 60. If these mass ratios are within this range, an adhesive composition with excellent adhesive properties can be prepared.

[0068] <<Styrene-based elastomers containing carboxyl groups>>

[0069] Styrene-based elastomers containing carboxyl groups have high adhesion, can impart flexibility to cured products, and are effective as components that impart good electrical properties.

[0070] By including a styrene-based elastomer containing carboxyl groups in the adhesive composition, even for substrates such as films and metal foils with good electrical properties and low polarity, the adhesive composition can fully follow the surface of the substrate, and the highly polar carboxyl groups can exhibit adhesion, thus improving the adhesion of the adhesive layer. Furthermore, since the styrene-based elastomer containing carboxyl groups is reactive, the heat resistance and chemical resistance of the adhesive layer are also improved after epoxy curing.

[0071] In addition, the presence of carboxyl groups improves the dispersibility of the filler in the dispersion.

[0072] The so-called styrene-based elastomers containing carboxyl groups refer to copolymers with block and random structures of conjugated diene compounds and aromatic vinyl compounds as the main components, as well as substances modified by modifying their hydrides with unsaturated carboxylic acids.

[0073] As examples of aromatic vinyl compounds and conjugated diene compounds, styrene-based elastomers are described in the <Styrene-based elastomers> section above.

[0074] Modification of styrene-based elastomers containing carboxyl groups can be achieved, for example, by copolymerizing unsaturated carboxylic acids during the polymerization of styrene-based elastomers. Alternatively, it can be achieved by heating and mixing styrene-based elastomers and unsaturated carboxylic acids in the presence of organic peroxides.

[0075] Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, maleic anhydride, and itaconic anhydride.

[0076] The preferred amount of unsaturated carboxylic acid modification is 0.1–10% by mass.

[0077] The acid value of the styrene-based elastomer containing carboxyl groups is preferably 0.1 to 25 mg KOH / g, more preferably 0.5 to 23 mg KOH / g. If the acid value is 0.1 mg KOH / g or higher, the adhesive composition cures sufficiently, resulting in good adhesion and heat resistance. On the other hand, if the acid value is 30 mg KOH / g or lower, the cohesive force of the adhesive composition is suppressed, thus resulting in excellent adhesion and electrical properties.

[0078] Furthermore, the weight-average molecular weight of the styrene-based elastomer containing carboxyl groups is preferably 10,000 to 500,000, more preferably 300,000 to 300,000, and even more preferably 500,000 to 200,000. If the weight-average molecular weight is above the lower limit mentioned above, it exhibits excellent adhesion, and its coatability is also good when it is dissolved in a solvent for coating. If the weight-average molecular weight is below the upper limit mentioned above, its compatibility with epoxy resin becomes good.

[0079] Weight-average molecular weight is a value obtained by converting the molecular weight determined by gel permeation chromatography (hereinafter also referred to as "GPC") to polystyrene.

[0080] The content of carboxyl-containing styrene-based elastomers relative to 100 parts by weight of the solid components of the adhesive composition is preferably 15 to 90 parts by weight. If the content is within this range, an adhesive composition with excellent adhesive properties can be prepared.

[0081] <<Styrene-based elastomers containing amino groups>>

[0082] By including an amino-containing styrene-based elastomer in the adhesive composition, the amino groups exhibit strong interactions with the low dielectric constant substrate film, increasing the reactivity of the adhesive composition and improving the adhesion of the adhesive layer. Furthermore, due to the reactivity of the amino-containing styrene-based elastomer, the heat resistance and chemical resistance of the adhesive layer are also improved after epoxy curing.

[0083] Because it contains amino groups, its adhesion to metals is improved.

[0084] Amino-containing styrene elastomers refer to copolymers with block and random structures of conjugated diene compounds and aromatic vinyl compounds as the main components, as well as substances obtained by amine modification of the hydrides.

[0085] As examples of aromatic vinyl compounds and conjugated diene compounds, styrene-based elastomers are described in the <Styrene-based elastomers> section above.

[0086] There are no particular limitations on the method for amine modification of styrene-based elastomers. Known methods can be used, such as: amine modification by polymerizing (hydrogenated) block copolymers using an amino-containing polymerization initiator; amine modification of (hydrogenated) copolymers by using an amino-containing unsaturated monomer as a copolymer raw material; and amine modification by reacting an amine modifier having two or more amino groups with a styrene-based elastomer containing carboxyl groups to form an amide structure or an imide structure.

[0087] Furthermore, the weight-average molecular weight of the amino-containing styrene elastomer is preferably 10,000 to 500,000, more preferably 300,000 to 300,000, and even more preferably 500,000 to 200,000. If the weight-average molecular weight is above the lower limit mentioned above, it exhibits excellent adhesion, and its coatability is also good when it is dissolved in a solvent for coating. If the weight-average molecular weight is below the upper limit mentioned above, its compatibility with epoxy resin becomes good.

[0088] The content of the amino-containing styrene-based elastomer is preferably 15 to 90 parts by weight relative to 100 parts by weight of the solid component of the adhesive composition. If the content is within this range, an adhesive composition with excellent adhesive properties can be prepared.

[0089] By mixing unmodified styrene-based elastomers and modified styrene-based elastomers, it is possible to maintain adhesion and adjust hardness, control MFR, and suppress resin flow.

[0090] From the viewpoint of ensuring a low relative permittivity and good adhesion of the adhesive composition, the total nitrogen content in the amino-containing styrene elastomer is preferably 50 to 5000 ppm, more preferably 200 to 3000 ppm. Excellent adhesion is exhibited when the total nitrogen content is above or below the lower limit mentioned above. Excellent electrical properties are observed when the total nitrogen content is below the upper limit mentioned above.

[0091] The total nitrogen content in styrene-based elastomers containing amino groups can be determined using a trace nitrogen analyzer ND-100 (manufactured by Mitsubishi Chemical Corporation) according to JIS-K2609.

[0092] <Epoxy Modified Resin>

[0093] Compared with ordinary epoxy resins, epoxy modified resins having the structure represented by the above formula (1) have a faster reaction rate with the carboxyl group in the above-mentioned carboxyl-containing styrene elastomer, the amino group in the above-mentioned amino-containing styrene elastomer, or a faster self-polymerization reaction rate, exhibiting high adhesion to the bonded object and heat resistance of the cured adhesive.

[0094] As a preferred embodiment of epoxy modified resin, an epoxy modified resin having a structure represented by the following formula (2) can be cited.

[0095]

[0096] (R 5 and R 6 Each independently represents an alkyl group with 10 or fewer carbon atoms. In the case where multiple structures represented by the above formula (2) exist in an epoxy-modified resin, R in each formula (2) 5 Each can be the same or different, and R in each equation (2) 6 They can be the same or different. * indicates a bonding group.

[0097] From the perspective of reducing steric hindrance near the epoxy group and ensuring the reaction proceeds fully, in the above equation (2), R 5 and R 6 More preferably, all are hydrogen.

[0098] The epoxy-modified resin is preferably an epoxy-modified resin containing unsaturated bonds other than aromatic rings such as olefin backbone and vinyl groups. By introducing unsaturated bonds other than aromatic rings such as olefin backbone and vinyl groups into the reaction related to epoxy groups, the reaction rate and crosslinking density can be promoted. As a result, even a small amount of compounding can improve heat resistance and chemical resistance. In addition, as described later, the unsaturated bonds other than aromatic rings are crosslinked through free radical polymerization, thereby increasing the crosslinking density of the epoxy-modified resin and improving heat resistance and chemical resistance.

[0099] As a preferred embodiment of epoxy modified resin, an epoxy modified resin having a structure represented by the following formula (3) can be cited.

[0100]

[0101] (R 7 and R 8 Each independently represents a hydrogen atom or an alkyl group having 10 or fewer carbon atoms. In the case where multiple structures represented by the above formula (3) exist in the epoxy modified resin, R in each formula (3) 7 Each can be the same or different, and R in each equation (3) 8 They can be the same or different. * indicates a bonding group.

[0102] In equation (3) above, R 7 and R 8 More preferably, all are hydrogen.

[0103] The epoxy modified resin is preferably an epoxy modified resin having the structure represented by formula (1) and the structure represented by formula (3) above, and more preferably an epoxy modified resin having the structure represented by formula (2) and the structure represented by formula (3) above.

[0104] As a preferred embodiment of the epoxy modified resin, an epoxy modified resin having at least one of the structures represented by formula (4) and formula (5) is mentioned. It is also preferred to have both the structure represented by formula (4) and the structure represented by formula (5).

[0105]

[0106] (R 9 and R 10 Each independently represents a hydrogen atom or an alkyl group having 10 or fewer carbon atoms. In the case where multiple structures represented by the above formula (4) exist in the epoxy modified resin, R in each formula (4) 9 Each can be the same or different, and R in each equation (4) 10 They can be the same or different. * indicates a bonding group.

[0107] In equation (4) above, R 9 and R 10 More preferably, all are hydrogen.

[0108]

[0109] (R 11 and R 12Each independently represents a hydrogen atom or an alkyl group having 10 or fewer carbon atoms. In the case where multiple structures represented by the above formula (5) exist in the epoxy modified resin, R in each formula (5) 11 Each can be the same or different, and R in each equation (5) 12 They can be the same or different. * indicates a bonding group.

[0110] In equation (5) above, R 11 and R 12 More preferably, all are hydrogen.

[0111] The epoxy modified resin is preferably an epoxy modified resin having at least one of the structures represented by formula (1), formula (4), and formula (5) above, and more preferably an epoxy modified resin having at least one of the structures represented by formula (2), formula (4), and formula (5) above.

[0112] In addition, epoxy modified resin having at least one of the structures represented by formula (1), formula (2), formula (3), formula (4), and formula (5) is preferred.

[0113] Furthermore, the epoxy-modified resin is preferably an epoxy-modified organic compound obtained by modifying an organic compound containing unsaturated bonds. By modifying an organic compound containing unsaturated bonds, the structure represented by the above formula (1) and the unsaturated bonds can coexist within the molecule through the modification rate, and the epoxy structure can be easily given the effect of unsaturated bonds other than the olefin skeleton and aromatic rings such as vinyl groups.

[0114] Here, the method of modifying organic compounds containing unsaturated bonds into epoxy-modified organic compounds is effective through the reaction of forming an epoxy skeleton by a peroxide. Examples of peroxides used include percarboxylic acid compounds such as performic acid, peracetic acid, and perpropionic acid.

[0115] The epoxy-modified resin is preferably an epoxy-modified elastomer obtained by modifying an elastomer containing unsaturated bonds. Epoxy-modified elastomers can impart flexibility to cured products, and by inhibiting the reduction in toughness of the cured product caused by epoxy curing, they can maintain the tightness of the laminate when bent, without reducing heat resistance or chemical resistance.

[0116] In addition, the epoxy-modified resin is preferably a styrene-based elastomer.

[0117] In epoxy modified resins having structures represented by formula (1) or formula (2) above, in addition to structures represented by formulas (3) to (5) above, it is also preferable to have styrene structural units.

[0118] This is because, along with the styrene-based elastomer contained in the adhesive resin composition of the present invention, the epoxy-modified resin is also a styrene-based elastomer. Therefore, when the two are mixed, compatibility can be improved, and the reaction with the carboxyl groups in the styrene-based elastomer containing carboxyl groups and the amino groups in the styrene-based elastomer containing amino groups can be carried out efficiently.

[0119] Examples of epoxy-modified resins include alicyclic epoxy compounds such as cyclohexane oxide, epoxy polybutadiene, and epoxy compounds of styrene-butadiene block copolymers.

[0120] More preferably, it is an epoxy compound of a styrene-butadiene block copolymer. Since the styrene-butadiene block copolymer contains unsaturated bonds, the structure represented by the above formula (1) and the unsaturated bonds can coexist in the molecule, and the reaction of the epoxy structure can easily impart the effect of unsaturated bonds other than the olefin skeleton and aromatic rings such as vinyl groups.

[0121] Commercially available epoxy compounds can also be used as epoxy-modified resins, such as Celloxide 2021P, Celloxide 2081, Celloxide 2000 (manufactured by Daicel), Epolead GT401, Epolead PB3600, Epolead PB4700 (manufactured by Daicel), Epofriend AT501, and Epofriend CT310 (manufactured by Daicel).

[0122] The weight-average molecular weight (Mw) of the epoxy modified resin is preferably 30,000 or more, and more preferably 50,000 or more. If the weight-average molecular weight is 30,000 or more, softening of the adhesive composition can be suppressed, and resin flow during heat pressing can be prevented. If the weight-average molecular weight is 50,000 or more, the flexibility of the epoxy modified resin is improved, and the toughness of the cured product is improved. Furthermore, the weight-average molecular weight (Mw) of the epoxy modified resin is preferably 200,000 or less, and more preferably 160,000 or less. If the weight-average molecular weight is 200,000 or less, compatibility with styrene-based elastomers is further improved. If the weight-average molecular weight is 160,000 or less, the elastic modulus of the adhesive composition can be reduced, allowing it to conform to the shape of the adhered objects.

[0123] The content of the epoxy modified resin relative to 100 parts by weight of the resin composition is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 2 parts by weight or more. If the content of the epoxy modified resin is 0.5 parts by weight or more, it can be epoxy cured with the modified styrene-based elastomer, resulting in improved adhesion. If the content of the epoxy modified resin is 1 part by weight or more, the adhesive composition is fully cured, ensuring good heat resistance. If the content of the epoxy modified resin is 2 parts by weight or more, the adhesive composition can undergo further crosslinking reaction, ensuring good chemical resistance. Furthermore, the content of the epoxy modified resin relative to 100 parts by weight of the resin composition is preferably 50 parts by weight or less, more preferably 25 parts by weight or less, and even more preferably 15 parts by weight or less. If the content of the epoxy modified resin is 50 parts by weight or less, low dielectric constant, heat resistance, and chemical resistance can be balanced. If the content of the epoxy modified resin is 25 parts by weight or less, the flexibility and adhesion of the cured adhesive composition are ensured. If the content of the above-mentioned epoxy modified resin is less than 15 parts by mass, it is possible to further reduce the dielectric constant.

[0124] The epoxy equivalent of the aforementioned epoxy-modified resin is preferably 200 g / eq. or more, more preferably 350 g / eq. or more, and even more preferably 900 g / eq. or more. If the epoxy equivalent of the epoxy-modified resin is 200 g / eq. or more, the epoxy backbone in the epoxy-modified resin will not be excessively dense, allowing the reaction with the modified elastomer to occur, forming a matrix in the adhesive composition, thereby improving heat resistance and chemical resistance. If the epoxy equivalent of the epoxy-modified resin is 350 g / eq. or more, the content of the epoxy backbone is reduced relative to the amount of epoxy-modified resin, improving electrical properties. If the epoxy equivalent of the epoxy-modified resin is 900 g / eq. or more, the adhesive composition becomes softer, improving adhesion. Furthermore, the epoxy equivalent of the epoxy-modified resin is preferably 20,000 g / eq. or less, more preferably 16,000 g / eq. or less, and even more preferably 10,000 g / eq. or less. If the epoxy equivalent of the epoxy-modified resin is 20,000 g / eq. or less, epoxy curing of the adhesive composition is possible, resulting in improved adhesion. If the epoxy equivalent of the epoxy-modified resin is 16,000 g / eq. or less, the crosslinking density of the cured adhesive composition increases, improving heat resistance and chemical resistance. If the epoxy equivalent of the epoxy-modified resin is 10,000 g / eq. or less, even with a small amount of epoxy-modified resin, it can form a matrix with the modified elastomer, thus maintaining heat resistance and chemical resistance while improving electrical properties.

[0125] Other ingredients

[0126] The adhesive composition of the present invention may contain other resin components in addition to the styrene-based elastomer and epoxy-modified resin described above. These other resin components may include, for example, other thermoplastic resins besides the styrene-based elastomer, to a degree that does not affect the function of the adhesive composition.

[0127] Other examples of the aforementioned thermoplastic resins include phenoxy resins, polyamide resins, bismaleimide resins, polyester resins, polycarbonate resins, polyphenylene ether resins, polyurethane resins, polyacetal resins, polyethylene resins, polypropylene resins, and polyvinyl resins. These thermoplastic resins can be used alone or in combination of two or more.

[0128] Furthermore, the adhesive composition of the present invention may contain, in addition to other resin components, fillers, free radical polymerization initiators, tackifiers, flame retardants, curing agents, curing accelerators, coupling agents, heat aging resistant agents, leveling agents, defoamers, inorganic fillers, pigments, and solvents to a degree that does not affect the function of the adhesive composition.

[0129] <<Packaging>>

[0130] The adhesive composition of the present invention preferably contains filler.

[0131] As fillers according to the present invention, inorganic fillers are preferred from the viewpoint of controlling heat resistance and mechanical properties of the adhesive composition. Among inorganic fillers, silicon-based inorganic fillers and boron nitride are preferred from the viewpoint of electrical properties. Furthermore, mica and talc, which can control the mechanical properties of the adhesive composition even in small quantities and also have excellent electrical properties, are preferred as silicon-based inorganic fillers.

[0132] Furthermore, as the filler involved in this invention, from the viewpoint of dispersibility and brittleness, organic fillers are preferred. From the viewpoint of electrical properties, styrene-based spherical fillers are preferred, and styrene-based hollow fillers are more preferred.

[0133] These can be used individually or in combination of two or more.

[0134] The filler content in the adhesive composition of the present invention is preferably 0.5 to 25 parts by volume relative to 100 parts by volume of the resin composition, and more preferably 1 to 15 parts by volume relative to 100 parts by volume of the resin composition.

[0135] The shape of the packing material is not particularly limited and can be appropriately selected according to the purpose. For example, the inorganic packing material can be either spherical or non-spherical. From the viewpoint of coefficient of thermal expansion (CTE) and film strength, non-spherical inorganic packing material is preferred. The shape of the non-spherical inorganic packing material can be any three-dimensional shape other than spherical (approximately perfect sphere), such as plate-like, flake-like, columnar, chain-like, and fibrous shapes. Among these, from the viewpoint of CTE and film strength, plate-like and flake-like inorganic packing materials are preferred, and plate-like inorganic packing materials are more preferred.

[0136] <<Free Radical Polymerization Initiators>>

[0137] The adhesive composition of the present invention preferably contains a free radical polymerization initiator.

[0138] The unsaturated bonds other than aromatic rings such as the olefin skeleton and vinyl groups mentioned above can crosslink the resin components even in free radical polymerization, which can further improve the adhesion, heat resistance, and chemical resistance of the adhesive layer.

[0139] There are no particular restrictions on the types of free radical polymerization initiators, and they can be appropriately selected according to the purpose. For example, peroxides that can be crosslinked at the same temperature as epoxy curing, and photopolymerization initiators that can be crosslinked in advance without epoxy curing can be cited.

[0140] Among free radical polymerization initiators, organic peroxides are a preferred embodiment, for example. By containing organic peroxides, the crosslinking density of the adhesive composition can be increased without containing highly polar functional groups, thereby further improving the adhesion, heat resistance, and chemical resistance of the adhesive layer.

[0141] Organic peroxides include, for example, benzoyl peroxide, lauroyl peroxide, tert-butyl peroxypentanoate, tert-butyl peroxyethylhexanoate, 1,1'-bis-(tert-butylperoxy)cyclohexane, tert-pentyl peroxy-2-ethylhexanoate, and tert-hexyl peroxy-2-ethylhexanoate.

[0142] Examples of such tackifiers include coumarone-indene resin, terpene resin, terpene-phenol resin, rosin resin, p-tert-butylphenol-acetylene resin, phenol-formaldehyde resin, xylene-formaldehyde resin, petroleum-based hydrocarbon resin, hydrogenated hydrocarbon resin, and turpentine-based resin. These tackifiers can be used alone or in combination of two or more.

[0143] The aforementioned flame retardants can be either organic or inorganic. Examples of organic flame retardants include melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium phosphate amide, ammonium polyphosphate amide, urethane phosphate, urethane polyphosphate, aluminum tri(diethyl)phosphonate, aluminum trimethylethyl phosphonate, aluminum tri(diphenyl)phosphonate, zinc bis(diethyl)phosphonate, zinc bis(methylethyl)phosphonate, zinc bis(diphenyl)phosphonate, and titanium bis(diethyl)phosphonate. Phosphorus-based flame retardants include titanium tetra(diethyl)phosphonate, titanium oxybis(methylethyl)phosphonate, titanium tetra(methylethyl)phosphonate, titanium oxybis(diphenyl)phosphonate, and titanium tetra(diphenyl)phosphonate; triazine compounds such as melamine, melamine, and melamine cyanurate; nitrogen-based flame retardants such as cyanuric acid compounds, isocyanuric acid compounds, triazole compounds, tetraazole compounds, diazo compounds, and urea; and silicon-based flame retardants such as organosilicon compounds and silane compounds. In addition, inorganic flame retardants include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, barium hydroxide, and calcium hydroxide; metal oxides such as tin oxide, aluminum oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, and nickel oxide; and zinc carbonate, magnesium carbonate, barium carbonate, zinc borate, and hydrated glass. Two or more of these flame retardants can be used in combination.

[0144] Examples of curing agents include amine-based curing agents and anhydride-based curing agents, but these are not limited to these. Examples of amine-based curing agents include melamine resins such as methylated melamine resin, butylated melamine resin, and benzoguanamine resin, as well as dicyandiamine and 4,4'-diphenyldiaminosulfone. Examples of anhydrides include aromatic anhydrides and aliphatic anhydrides. These curing agents can be used alone or in combination of two or more.

[0145] The aforementioned curing accelerators, for example, are used to promote the reaction between styrene-based elastomers, particularly modified styrene-based elastomers, and epoxy resins. Tertiary amine-based curing accelerators, tertiary amine salt-based curing accelerators, and imidazole-based curing accelerators can be used.

[0146] Examples of tertiary amine curing accelerators include benzyl dimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, tetramethylguanidine, triethanolamine, N,N'-dimethylpiperazine, triethylenediamine, and 1,8-diazabicyclo[5.4.0]undecene.

[0147] Examples of tertiary amine salt curing accelerators include 1,8-diazabicyclo[5.4.0]undecene, formate, octanoate, p-toluenesulfonate, phthalate, phenolate or phenolic varnish resin salt, and 1,5-diazabicyclo[4.3.0]nonene, formate, octanoate, p-toluenesulfonate, phthalate, phenolate or phenolic varnish resin salt, etc.

[0148] Examples of imidazole-based curing accelerators include 2-methylimidazolium, 2-undecylimidazolium, 2-heptadecylimidazolium, 1,2-dimethylimidazolium, 2-methyl-4-ethylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, 1-benzyl-2-methylimidazolium, 1-benzyl-2-phenylimidazolium, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine, and 2,4-diamino-6-[2'- Undecylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazolyl isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazolium, 2-phenyl-4-methyl-5-hydroxymethylimidazolium, etc. These curing accelerators can be used alone or in combination of two or more.

[0149] In addition, examples of the aforementioned coupling agents include vinyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-acryloyloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatepropyltriethoxysilane, imidazole silane, and other silane-based coupling agents; titanate-based coupling agents; aluminate-based coupling agents; and zirconium-based coupling agents. These can be used alone or in combination of two or more.

[0150] Examples of heat-resistant antioxidants include 2,6-di-tert-butyl-4-methylphenol, n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate, tetra[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenol), triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate, sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate and dimyristyl-3,3'-dithiopropionate, and phosphorus-based antioxidants such as trinonylphenyl phosphite and tris(2,4-di-tert-butylphenyl)phosphite.

[0151] Examples of inorganic fillers include powders containing titanium dioxide, aluminum oxide, zinc oxide, carbon black, silicon dioxide, copper, and silver. These can be used alone or in combination of two or more.

[0152] (Adhesive layer)

[0153] The adhesive layer of the present invention comprises the adhesive composition of the present invention described above.

[0154] The adhesive composition that forms the adhesive layer can cure.

[0155] There are no particular limitations on the curing method; it can be appropriately selected according to the purpose. For example, thermosetting can be mentioned.

[0156] The thickness of the adhesive layer is not particularly limited and can be appropriately selected according to the purpose. For example, it is preferably 3 to 100 μm, more preferably 3 to 50 μm, and even more preferably 5 to 30 μm.

[0157] <Method for manufacturing adhesive layer>

[0158] By forming the above adhesive composition into a film, an adhesive layer can be manufactured.

[0159] The above-described adhesive composition can be manufactured by mixing a resin composition comprising a styrene-based elastomer and an epoxy-modified resin having the structure represented by formula (1) above, and other components as needed. The mixing method is not particularly limited, as long as the adhesive composition becomes homogeneous. The adhesive composition is preferably used in solution or dispersion form, and therefore a solvent is typically used as well.

[0160] Examples of solvents include alcohols such as methanol, ethanol, isopropanol, n-propanol, isobutanol, n-butanol, benzyl alcohol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, and diacetone alcohol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl pentyl ketone, cyclohexanone, and isophorone; aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and mesitylene; esters such as methyl acetate, ethyl acetate, butyl acetate, ethylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; and aliphatic hydrocarbons such as hexane, heptane, cyclohexane, and methylcyclohexane. These solvents can be used alone or in combination of two or more.

[0161] If the adhesive composition is a solvent-containing solution or dispersion (resin varnish), the coating of the substrate film and the formation of the adhesive layer can be carried out smoothly, and the desired thickness of the adhesive layer can be easily obtained.

[0162] When the adhesive composition contains a solvent, from the viewpoint of operability in forming the adhesive layer, the concentration of the solid component is preferably in the range of 3 to 80% by mass, more preferably 10 to 50% by mass. If the concentration of the solid component is 80% by mass or less, the viscosity of the solution is moderate, and it is easy to coat evenly.

[0163] As a more specific embodiment of the adhesive layer manufacturing method, after applying a resin varnish containing the above-described adhesive composition and solvent to the surface of a substrate film to form a resin varnish layer, the solvent is removed from the resin varnish layer, thereby forming an adhesive layer in a grade B state. Here, a grade B adhesive layer refers to a state where the adhesive composition is in an uncured state or a semi-cured state where some curing has begun, and further curing of the adhesive composition is carried out by heating or the like.

[0164] Here, there are no particular limitations on the method of coating resin varnish on the substrate film, and appropriate methods can be selected according to the purpose. Examples include spraying, spin coating, dipping, roller coating, doctor blade coating, doctor blade roller coating, scraping, curtain coating, slot coating, screen printing, inkjet printing, and dispensing.

[0165] The adhesive layer in the aforementioned Grade B state can be further subjected to heating or other processes to form a cured adhesive layer.

[0166] <Properties of the Adhesive Layer>

[0167] The adhesive layer formed by curing the adhesive composition of the present invention preferably has a relative permittivity (εr) of 3 or less at a frequency of 28 GHz, more preferably 2.7 or less. The dielectric loss tangent (tanδ) of the adhesive layer at a frequency of 28 GHz is preferably 0.004 or less, more preferably 0.0025 or less, and even more preferably 0.002 or less.

[0168] If the relative permittivity is 3 or less and the dielectric loss tangent is 0.004 or less, it can also be used in high-frequency FPC-related products with stringent electrical characteristic requirements. Furthermore, if the relative permittivity is 2.7 or less and the dielectric loss tangent is 0.0025 or less, it can meet the electrical characteristics expected of components in 5G high-frequency FPC-related products, achieving electrical characteristics equivalent to LCP, and can also be appropriately used in 5G high-frequency FPC-related products with stringent electrical characteristic requirements. Moreover, if the dielectric loss tangent is 0.002 or less, it is possible to manufacture high-frequency FPC-related products with further improved transmission characteristics.

[0169] [Relative permittivity and dielectric loss tangent]

[0170] The relative permittivity and dielectric loss tangent of the adhesive layer were measured using a network analyzer MS46122B (manufactured by Anritsu) and an open resonator Fabry-Perot DPS-03 (manufactured by KEYCOM) via the open resonator method at a temperature of 23°C and a frequency of 28 GHz.

[0171] (Layered structure)

[0172] The laminate of the present invention comprises a substrate film and the aforementioned adhesive layer on at least one surface of the substrate film.

[0173] <Substrate Film>

[0174] The substrate film used in this invention can be selected according to the intended use of the laminate. For example, when the laminate is used as a cover film or a copper-clad laminate (CCL), examples include polyimide films, polyetheretherketone (PEEK) films, polyphenylene sulfide (PPS) films, aromatic polyamide films, polyethylene naphthalate (PEG) films, and liquid crystal polymer films. Among these, from the viewpoint of adhesion and electrical properties, polyimide films, PEEK films, PEG films, and liquid crystal polymer films are preferred.

[0175] In addition, when the laminate of the present invention is used as a bonding sheet, the substrate film needs to be a release film, such as polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release paper, polyolefin resin coated paper, TPX (polymethylpentene) film and fluorine resin film.

[0176] When the laminate of the present invention is used as a shielding film, the substrate film needs to be a film with electromagnetic wave shielding capability, such as a laminate that protects an insulating layer and a metal foil.

[0177] (Covering film)

[0178] As a preferred embodiment of the laminate of the present invention, a covering film can be cited.

[0179] In the manufacture of FPCs, a laminate with an adhesive layer called a "cover film" is typically used to protect the wiring portion. This cover film has an insulating resin layer and an adhesive layer formed on its surface.

[0180] For example, the cover film has the adhesive layer formed on at least one surface of the substrate film, and is a laminate that is usually difficult to peel off from the substrate film and the adhesive layer.

[0181] The thickness of the substrate film included in the cover film is preferably 5 to 100 μm, more preferably 5 to 50 μm, and even more preferably 5 to 30 μm. If the thickness of the substrate film is below the upper limit mentioned above, the cover film can be made into a thin film. If the thickness of the substrate film is above the lower limit mentioned above, the design of the printed circuit board becomes easier and the operation is also more convenient.

[0182] As a method for manufacturing a cover film, for example, a resin varnish containing the above-mentioned adhesive composition and solvent is applied to the surface of the above-mentioned substrate film to form a resin varnish layer, and then the solvent is removed from the resin varnish layer, thereby enabling the manufacture of a cover film having an adhesive layer in a B-grade state.

[0183] The drying temperature for removing the solvent is preferably 40–250°C, more preferably 70–170°C.

[0184] Drying is performed by passing the laminate coated with the adhesive composition through an oven subjected to hot air drying, far-infrared heating, and high-frequency induction heating.

[0185] It should be noted that, as needed, a release film may be laminated onto the surface of the adhesive layer for storage or other purposes. Known films such as polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release paper, polyolefin resin coated paper, TPX film, and fluorinated resin film can be used as the release film.

[0186] The cover film of the present invention, due to the use of the low dielectric adhesive composition of the present invention, enables high-speed transmission in electronic devices and exhibits excellent adhesion stability to electronic devices.

[0187] (Adhesive sheet)

[0188] As a preferred embodiment of the laminate of the present invention, an adhesive sheet can be cited.

[0189] The adhesive sheet has the aforementioned adhesive layer formed on the surface of the release film (substrate film). Alternatively, the adhesive sheet may also be in the form of having an adhesive layer between two release films. When using the adhesive sheet, the release film is peeled off. The release film can be the same film described in the (covering film) section above.

[0190] The thickness of the substrate film contained in the adhesive sheet is preferably 5 to 100 μm, more preferably 25 to 75 μm, and even more preferably 38 to 50 μm. If the thickness of the substrate film is within the above range, the adhesive sheet is easy to manufacture and can be operated.

[0191] One method for manufacturing an adhesive sheet includes, for example, coating the surface of a release film with a resin varnish containing the above-described adhesive composition and solvent, and then drying it in the same manner as the case of the cover film.

[0192] The adhesive sheet of the present invention uses the low dielectric adhesive composition of the present invention, thus enabling high-speed transmission in electronic devices and exhibiting excellent bonding stability with electronic devices.

[0193] (Copper-clad laminate (CCL))

[0194] As a preferred embodiment of the laminates involved in this invention, a copper-clad laminate formed by bonding copper foil to the adhesive layer of the laminates of this invention can be cited.

[0195] Copper-clad laminates use the above-described laminate to bond copper foil, for example, in the order of substrate film, adhesive layer, and copper foil. It should be noted that the adhesive layer and copper foil can also be formed on both sides of the substrate film.

[0196] The adhesive composition used in this invention also exhibits excellent adhesion to articles containing copper.

[0197] The copper-clad laminate of the present invention uses the low-dielectric adhesive composition of the present invention, thus enabling high-speed transmission in electronic devices and exhibiting excellent adhesive stability.

[0198] A method for manufacturing copper-clad laminates includes, for example, the following steps: bringing the adhesive layer of the laminate into contact with the copper foil surface, performing hot lamination at 80°C to 200°C, and then curing the adhesive layer by post-curing. The post-curing conditions, for example, can be set to 100°C to 200°C for 30 minutes to 4 hours in an inert gas atmosphere. It should be noted that the copper foil is not particularly limited, and electrolytic copper foil, rolled copper foil, etc., can be used.

[0199] (Printed Circuit Board)

[0200] As a preferred embodiment of the laminated body of the present invention, a printed circuit board formed by bonding copper wiring to the adhesive layer of the laminated body of the present invention can be cited.

[0201] Printed circuit boards are obtained by forming electronic circuits on the aforementioned copper-clad laminate.

[0202] The printed circuit board uses the above-described laminate to bond the substrate film and copper wiring, arranged in the order of substrate film, adhesive layer, and copper wiring. It should be noted that the adhesive layer and copper wiring can also be formed on both sides of the substrate film.

[0203] For example, a cover film is attached to the surface with wiring portions through an adhesive layer using hot pressing or similar methods, thereby manufacturing a printed circuit board.

[0204] The printed circuit board of the present invention uses the low dielectric adhesive composition of the present invention, thus enabling high-speed transmission in electronic devices and exhibiting excellent adhesive stability.

[0205] A method for manufacturing the printed circuit board according to the present invention includes, for example, the following steps: contacting the adhesive layer of the aforementioned laminate with copper wiring, performing hot lamination at 80°C to 200°C, and then curing the adhesive layer by post-curing. The post-curing conditions can be, for example, set to 100°C to 200°C for 30 minutes to 4 hours. The shape of the aforementioned copper wiring is not particularly limited; an appropriate shape can be selected according to preference.

[0206] (Shielding film)

[0207] As a preferred embodiment of the laminated body involved in the present invention, a shielding film can be cited.

[0208] Shielding films are films used to shield various electronic devices, such as computers, mobile phones, and analytical equipment, from electromagnetic noise that can cause malfunctions. They are also known as electromagnetic wave shielding films.

[0209] An electromagnetic wave shielding film, for example, is formed by sequentially stacking an insulating resin layer, a metal layer, and the adhesive layer involved in this invention.

[0210] The shielding film of the present invention uses the low dielectric adhesive composition of the present invention, thus enabling high-speed transmission in electronic devices and exhibiting excellent adhesion stability to electronic devices.

[0211] (Printed circuit board with shielding film)

[0212] As a preferred embodiment of the laminate involved in this invention, a printed circuit board with a shielding film can be cited.

[0213] A printed circuit board with a shielding film is formed by attaching the aforementioned electromagnetic wave shielding film to a printed circuit board on which printed lines are provided on at least one side of a substrate.

[0214] A printed circuit board with a shielding film, for example, has a printed circuit board, an insulating film adjacent to the surface of the printed circuit board on which the printed circuit board is disposed, and the aforementioned electromagnetic wave shielding film.

[0215] The printed circuit board with shielding film involved in this invention uses the low dielectric adhesive composition of this invention, thus enabling high-speed transmission in electronic devices and exhibiting excellent adhesive stability.

[0216]

Example

[0217] The present invention will now be described in more detail with reference to specific embodiments, but the scope of the invention is not limited to these embodiments. It should be noted that, unless otherwise specified, parts and percentages are based on mass.

[0218] (Styrene-based elastomers containing carboxyl groups)

[0219] The product used is "Tuftec M1911" (maleic acid modified styrene-ethylene butene-styrene block copolymer) manufactured by Asahi Kasei Corporation. The copolymer has an acid value of 2 mg KOH / g, a styrene / ethylene butene ratio of 30 / 70, and a weight-average molecular weight of 69,000.

[0220] (Styrene-based elastomers containing carboxyl groups)

[0221] The product used is "Tuftec M1913" (maleic acid modified styrene-ethylene butene-styrene block copolymer) manufactured by Asahi Kasei Corporation. The copolymer has an acid value of 10 mg KOH / g, a styrene / ethylene butene ratio of 30 / 70, and a weight-average molecular weight of 67,000.

[0222] (Styrene-based elastomers containing carboxyl groups)

[0223] The product used is Kraton FG1901 (maleic acid modified styrene-ethylene-butene-styrene block copolymer), manufactured by Kraton. This copolymer has an acid value of 19 mg KOH / g, a styrene / ethylene-butene ratio of 30 / 70, and a weight-average molecular weight of 81,000.

[0224] (Styrene-based elastomers without carboxyl groups)

[0225] The copolymer used is "Tuftec P1500" (hydrogenated styrene elastomer) manufactured by Asahi Kasei Corporation. The copolymer has an acid value of 0 mg KOH / g, a styrene / ethylene-butene ratio of 30 / 70, and a weight-average molecular weight of 67,000.

[0226] (Unmodified styrene-based elastomer)

[0227] The product used is "Kraton G1651" (styrene-ethylene-butene-styrene block copolymer) manufactured by Kraton. This copolymer has an acid value of 0 mg KOH / g, a styrene / ethylene-butene ratio of 33 / 67, and a weight-average molecular weight of 136,700.

[0228] (Styrene-based elastomers containing amino groups)

[0229] The product used is "TuftecMP10" (amine-modified styrene-ethylene-butene-styrene copolymer) manufactured by Asahi Kasei Corporation. This copolymer has a styrene / ethylene-butene ratio of 30 / 70 and a weight-average molecular weight of 78,000. The total nitrogen content of this copolymer is 430 ppm (μg / g).

[0230] (Epoxy modified resin)

[0231] The product used is "Epofriend AT501" (epoxide of styrene-butadiene block copolymer) manufactured by Daicel Co., Ltd. This copolymer has a styrene / ethylene-butene ratio of 40 / 60, a weight-average molecular weight of 92,000, and an epoxy equivalent of 1055 g / eq.

[0232] (Epoxy modified resin)

[0233] The product used is "EpofriendCT310" (epoxide of styrene-butadiene block copolymer) manufactured by Daicel Co., Ltd. This copolymer has a styrene / ethylene-butene ratio of 40 / 60, a weight-average molecular weight of 93,000, and an epoxy equivalent of 2125 g / eq.

[0234] (Epoxy resin)

[0235] The epoxy resin used is a phenolic varnish-type epoxy resin, manufactured by Mitsubishi Chemical Corporation under the trade name "YX7700" (softening point 65°C). The epoxy equivalent is 270 g / eq.

[0236] (Epoxy resin)

[0237] The epoxy resin used is a phenolic varnish-type epoxy resin, manufactured by DIC Corporation under the trade name "HP-7200" (epoxy resin, softening point 56-66℃). The epoxy equivalent is 259 g / eq.

[0238] (PERBUTYL E)

[0239] As an organic peroxide, the peroxide ester manufactured by Nippon Oil Co., Ltd. is used under the trade name "PERBUTYL E".

[0240] (MK-100DS)

[0241] The mica used is manufactured by Katakura CO-OP AGRI Co., Ltd., with an average particle size of 3μm, and is marketed under the name "MK-100DS".

[0242] (UHP-S2)

[0243] The product used is flake-shaped boron nitride with an average particle size of 0.7 μm, manufactured by Showa Denko Corporation, and is marketed under the trade name "UHP-S2".

[0244] (OP935)

[0245] The flame retardant used is manufactured by Clariant Chemicals Co., Ltd. and is marketed under the trade name "OP935".

[0246] (solvent)

[0247] Use a mixed solvent containing toluene and methyl ethyl ketone (mass ratio = 90:10).

[0248] (Substrate film)

[0249] As the substrate film, "Shin-Etsu Sepla Film PEEK" (polyether ether ketone, 50 μm thick) manufactured by Shin-Etsu Polymer Co., Ltd. was used.

[0250] (Electrolytic copper foil)

[0251] As the electrolytic copper foil, “TQ-M7-VSP” (electrolytic copper foil, 12 μm thickness, with a gloss surface Rz of 1.27 μm, a gloss surface Ra of 0.197 μm, and a gloss surface Rsm of 12.95 μm) manufactured by Mitsui Metal Mining was used. The surface roughness of the gloss surface was determined using a roughness profile measured with a laser microscope, and the value was calculated based on JIS B0601:2013 (ISO 4287:1997 Amd.1:2009).

[0252] (Mold release film)

[0253] As the release film, NP75SA (silicone release PET film, 75μm) manufactured by PANAC was used.

[0254] (Determination of nitrogen content)

[0255] The total nitrogen content in the amino-containing styrene elastomers used in the examples was determined by the following method.

[0256] <Determination Method>

[0257] The results were obtained using a trace nitrogen analyzer ND-100 (manufactured by Mitsubishi Chemical Corporation) according to JIS-K2609.

[0258] (Example 1)

[0259] A resin varnish with a solid content of 20% by mass is prepared by dissolving the components constituting the adhesive layer shown in Table 1 in a solvent.

[0260] The surface of the substrate film is subjected to corona treatment.

[0261] The resin varnish is applied to the surface of the substrate film and dried in an oven at 110°C for 4 minutes to allow toluene to evaporate, thereby forming an adhesive layer and obtaining a substrate film with adhesive. The adhesive layer of the adhesive laminate is overlapped with the glossy surface of the electrolytic copper foil in contact with the laminate, and then hot-laminated at 120°C to obtain a pre-cured adhesive laminate. The adhesive layer is then cured by post-curing the pre-cured adhesive laminate to obtain a cured adhesive laminate.

[0262] The adhesion force (N / cm) between the electrolytic copper foil and the substrate film of the cured adhesive laminate in Example 1 was measured.

[0263] [Adhesion Force (N / cm)]

[0264] Adhesion strength is determined by cutting the cured adhesive laminate into a test specimen with a width of 25 mm, according to JIS Z0237:2009 (Test Method for Adhesive Tape / Sheet), under the conditions of peel speed of 0.3 m / min and peel angle of 180°, by measuring the peel strength when peeling electrolytic copper foil from an adhesive-coated substrate film fixed to a support.

[0265] For the adhesive layer in the cured adhesive laminate of Example 1, the relative permittivity and dielectric loss tangent were also measured at a frequency of 28 GHz.

[0266] [Relative permittivity and dielectric loss tangent]

[0267] The relative permittivity and dielectric loss tangent of the adhesive layer were measured using an MS46122B network analyzer (Anritsu) and an open resonator Fabry-Perot DPS-03 (KEYCOM) via the open resonator method at 23°C and 28GHz. For the test samples, a resin varnish was rolled onto a release film. The coated film was then dried in an oven at 110°C for 4 minutes to form a Grade B adhesive layer (50 μm thick). Next, the adhesive layer was heat-laminated at 120°C with the adhesive surfaces joined together to form a pre-cured adhesive film (100 μm thick). This pre-cured adhesive film (100 μm thick) was then cured in an oven at 150°C for 60 minutes to produce a cured adhesive film (100 mm × 100 mm). The release film was peeled off from the cured adhesive film, and the relative permittivity and dielectric loss tangent of the adhesive layer were measured.

[0268] The heat resistance of the adhesive layer in the laminate of Example 1 was evaluated by solder heat resistance test.

[0269] [Solder Heat Resistance Test]

[0270] The solder heat resistance test was conducted on the substrate film. The cured adhesive laminate was floated in a solder bath at 288°C for 10 seconds for 3 times to check for any abnormalities in the appearance of the adhesive layer, such as expansion or peeling.

[0271] The heat resistance of laminates is evaluated using the following evaluation criteria.

[0272] ◎No abnormalities (no dissolution).

[0273] ○No abnormalities were found in the end, but softening of the adhesive layer was observed during the test.

[0274] △ No peeling was performed, but softening of the adhesive layer and the formation of a "spotted pattern" were observed.

[0275] × Peeling.

[0276] The measurement results are shown in Table 3.

[0277] (Examples 2 to 15)

[0278] In Example 1, as shown in Table 1, the types and amounts of the components constituting the adhesive layer were changed, but otherwise the process was the same as in Example 1, and the laminates of Examples 2 to 15 were produced.

[0279] The fabricated laminate was evaluated in the same manner as in Example 1.

[0280] The results are shown in Table 3.

[0281] (Comparative Examples 1 to 11)

[0282] In Example 1, as shown in Table 2, the types and amounts of the components constituting the adhesive layer were changed, but otherwise the process was the same as in Example 1, and the laminates of Comparative Examples 1 to 11 were produced.

[0283] The fabricated laminate was evaluated in the same manner as in Example 1.

[0284] The results are shown in Table 4.

[0285] [Table 1]

[0286]

[0287] [Table 2]

[0288]

[0289] [Table 3]

[0290]

[0291] [Table 4]

[0292]

[0293] As shown in the examples, the adhesive layer containing the adhesive composition of the present invention exhibits good electrical properties (dielectric properties) capable of handling 5G, and also has excellent adhesion, heat resistance, and solvent resistance.

[0294] Industrial availability

[0295] Laminates having adhesive layers comprising the adhesive composition of the present invention can be suitably used in the manufacture of FPC-related products for electronic devices such as smartphones, mobile phones, optical components, digital cameras, game consoles, laptops, and medical devices.

Claims

1. An adhesive composition, characterized in that, Contains: styrene-based elastomers containing amino groups and epoxy-modified resins. The content of the amino-containing styrene elastomer is 15 to 90 parts by weight relative to 100 parts by weight of the solid components of the adhesive composition. The content of the epoxy modified resin is 0.5 to 25 parts by weight relative to 100 parts by weight of the adhesive composition. The epoxy-modified resin has a structure represented by the following formula (2). The epoxy modified resin is selected from any one of alicyclic epoxy compounds, epoxidized polybutadiene, and styrene-butadiene block copolymers. The epoxy equivalent of the epoxy modified resin is 350 g / eq or more and 20,000 g / eq or less. The adhesive layer formed by curing the adhesive composition has a relative permittivity of 3 or less and a dielectric loss tangent of 0.004 or less, as measured at a frequency of 28 GHz. ； In formula (2), R 5 and R 6 each independently represent hydrogen, or an alkyl group having 10 or less carbon atoms, in the case where a plurality of the structures represented by formula (2) described above are present in the epoxy-modified resin, R 5 each are the same or different, and R 6 each are the same or different, and * represents a bonding group.

2. The adhesive composition according to claim 1, wherein, The epoxy-modified resin contains unsaturated bonds other than aromatic rings.

3. The adhesive composition according to claim 2, wherein, The epoxy-modified resin has the structure represented by the following formula (3). ； In equation (3), R 7 and R 8 Each of the above formulas (3) independently represents hydrogen or an alkyl group having 10 or fewer carbon atoms. In the case where multiple structures represented by these formulas (3) exist in the epoxy modified resin, R in each formula (3) represents hydrogen or an alkyl group having 10 or fewer carbon atoms. 7 Whether they are the same or different, R in each equation (3) 8 They may be the same or different; * indicates a bonding group.

4. The adhesive composition according to claim 1, wherein, R in equation (2) 5 and R 6 Both are hydrogen.

5. The adhesive composition according to claim 1, wherein, The epoxy-modified resin is an epoxy compound of styrene-butadiene block copolymer.

6. The adhesive composition according to claim 1, wherein, The epoxy-modified resin also has the structure represented by the following formula (5), ； In equation (5), R 11 and R 12 Each of the above formulas (5) independently represents an alkyl group with 10 or fewer carbon atoms. In the case where multiple structures represented by these formulas exist in the epoxy modified resin, R in each formula (5) represents... 11 Whether they are the same or different, R in each equation (5) 12 They may be the same or different; * indicates a bonding group.

7. The adhesive composition according to claim 1, wherein, The weight-average molecular weight (Mw) of the epoxy modified resin is above 30,000 and below 200,000.

8. The adhesive composition according to claim 1, wherein, The adhesive composition contains a free radical polymerization initiator.

9. An adhesive layer, characterized in that, It is formed by curing the adhesive composition according to any one of claims 1 to 8.

10. A laminated body, characterized in that, have: Substrate film; and The adhesive layer as described in claim 9.

11. The laminate according to claim 10, wherein, The substrate film contains polyetheretherketone (PEEK) resin.

Images