JP2023021033A - Resin composition, resin sheet, laminate, sheet cured product and circuit board material - Google Patents

Abstract

To provide a sheet cured product and a circuit board material which have low dielectric characteristics and heat resistance, and a resin composition, a resin sheet and a laminate which enable manufacture of the sheet cured product and the circuit board material having the low dielectric characteristics and the heat resistance.SOLUTION: A resin composition contains at least one thermoplastic resin (A) selected from the group consisting of a styrenic thermoplastic elastomer, an olefinic thermoplastic elastomer and an ethylenic polymer, monofunctional (meth)acrylate (B) having a long-chain alkyl group and polyfunctional (meth)acrylate (C), wherein the total of the contents of the monofunctional (meth)acrylate (B) having the long-chain alkyl group and the polyfunctional (meth)acrylate (C) with respect to 100 pts.mass of the thermoplastic resin (A) is 1 pts.mass or more and less than 30 pts.mass. A resin sheet is composed of the resin composition. A laminate has a release film on one or both surfaces of the resin sheet.SELECTED DRAWING: None

Description

The present invention relates to resin compositions, resin sheets, laminates, cured sheets, and circuit board materials.

2. Description of the Related Art In recent years, as electrical and electronic devices have become more sophisticated and functional, communication frequencies have been increasing in order to improve the communication speed and the amount of information to be transmitted.
When a digital signal is sent through a circuit board, part of the transmitted digital signal is thermally converted in the circuit board, resulting in transmission loss. Since the amount of transmission loss is represented by the product of the relative permittivity and the dielectric loss tangent, materials with low relative permittivity and dielectric loss tangent, that is, members with low dielectric properties are required in order to achieve low-loss communication. In particular, since transmission signals in a high frequency range are more likely to be converted into heat, materials with lower dielectric properties are desired.
On the other hand, as the circuits in electrical and electronic equipment become more highly integrated, the amount of heat generated inside the electrical and electronic equipment also increases, so circuit board materials are also required to have heat resistance.

Materials having low dielectric properties include, for example, polyphenylene ether resin compositions containing an epoxy compound and a cyanate compound (see, for example, Patent Document 1), and thermosetting maleimide resins (see, for example, Patent Document 2). Thermoplastic resins such as cycloolefin-based resins and cyclic olefin-based resin compositions (see, for example, Patent Document 3) are known.

JP 2010-059363 A JP 2012-255059 A WO2006/095511

However, conventional thermosetting resins tend to have higher relative permittivity and dielectric loss tangent than thermoplastic resins, and it has been necessary to add a large amount of inorganic particles or the like to achieve low dielectric properties.
On the other hand, although conventional thermoplastic resins have low dielectric properties, they sometimes have poor heat resistance.

Accordingly, the present invention provides a cured sheet material having low dielectric properties and heat resistance and a circuit board material, and the cured sheet material having low dielectric properties and heat resistance and the circuit board. An object of the present invention is to provide a resin composition, a resin sheet, and a laminate from which materials can be manufactured.

As a result of intensive studies aimed at solving the above problems, the inventors of the present invention have found that the above problems can be solved by adding a specific compound to a thermoplastic resin.

The gist of the present invention is as follows.
[1] At least one thermoplastic resin (A) selected from the group consisting of styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers and ethylene-based polymers, and a monofunctional (meth)acrylate having a long-chain alkyl group ( B) and a polyfunctional (meth)acrylate (C), and the monofunctional (meth)acrylate (B) having the long-chain alkyl group and the polyfunctional (C) with respect to 100 parts by mass of the thermoplastic resin (A) A resin composition in which the total content of (meth)acrylate (C) is 1 part by mass or more and less than 30 parts by mass.
[2] The resin composition according to [1] above, which contains a styrene-based thermoplastic elastomer as the thermoplastic resin (A).
[3] The resin composition according to [1] above, wherein the styrene content of the styrene-based thermoplastic elastomer is 10% by mass or more and 70% by mass or less.
[4] The mass ratio (B):(C) of the monofunctional (meth)acrylate (B) having a long-chain alkyl group and the polyfunctional (meth)acrylate (C) is 50:50 to 99:1. The resin composition according to any one of [1] to [3] above.
[5] The polar functional group equivalent weight of the monofunctional (meth)acrylate (B) having a long-chain alkyl group (molecular weight of the monofunctional (meth)acrylate (B) having a long-chain alkyl group/molecular weight of the polar functional group) is 2 or more, the resin composition according to any one of the above [1] to [4].
[6] The above [1] to wherein the polar functional group equivalent of the polyfunctional (meth)acrylate (C) (molecular weight of the polyfunctional (meth)acrylate (C)/molecular weight of the polar functional group) is 1.5 or more The resin composition according to any one of [5].
[7] A resin sheet made of the resin composition according to any one of [1] to [6] above.
[8] A laminate comprising a release film on one or both surfaces of the resin sheet according to [7] above.
[9] A cured sheet obtained by curing the resin sheet according to [7] above.
[10] A circuit board material obtained by laminating an insulating layer made of the resin sheet according to [7] above and a conductor.

According to the present invention, a cured sheet material having low dielectric properties and heat resistance and a circuit board material, and the cured sheet material having low dielectric properties and heat resistance and the circuit board A resin composition, a resin sheet and a laminate from which materials can be manufactured can be obtained.

Although the present invention will be described in detail below, the following description is an example of an embodiment of the present invention, and the present invention is not limited to the following description unless it exceeds the gist thereof.
In the following, when the expression "~" is used, it is used as an expression including numerical values or physical property values before and after it.

<Resin composition>
A resin composition according to one embodiment of the present invention (hereinafter also referred to as "this composition") is at least one selected from the group consisting of styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers and ethylene-based polymers. of a thermoplastic resin (A), a monofunctional (meth)acrylate (B) having a long-chain alkyl group, and a polyfunctional (meth)acrylate (C).
The reason why the heat resistance of the cured sheet material and the circuit board material made of this composition is good is not clear, but when the composition is cured, a single monolayer having a long-chain alkyl group entangled with the thermoplastic resin (A) is obtained. This is probably because the functional (meth)acrylate (B) and the polyfunctional (meth)acrylate (C) artificially increase the crosslink density and improve the elastic modulus.
Each component of the present composition will be described below.

1. Thermoplastic resin (A)
The thermoplastic resin (A) of the present composition is at least one selected from the group consisting of styrene thermoplastic elastomers, olefinic thermoplastic elastomers and ethylene polymers.

Examples of the styrene-based thermoplastic elastomer include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), and hydrogenated styrene-ethylene-butadiene-styrene blocks of these. copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-isobutylene-styrene-block copolymer (SIBS), and the like.

The olefinic thermoplastic elastomer contains a polyolefin as a hard segment and a rubber component as a soft segment.
The olefin-based thermoplastic elastomer may be a mixture (polymer blend) of polyolefin and rubber component, or may be a cross-linked product obtained by subjecting polyolefin and rubber component to a cross-linking reaction. Polyolefin and rubber component are polymerized. It may be a polymer obtained by
Polypropylene, polyethylene, etc. are mentioned as said polyolefin.
Examples of the rubber component include diene rubbers such as isoprene rubber, butadiene rubber, butyl rubber, propylene-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-isoprene rubber, ethylene-propylene non-conjugated diene rubber, ethylene-butadiene copolymer rubber, and the like. mentioned.

Examples of the ethylene-based polymer include homopolymers of ethylene and copolymers of ethylene and other monomers.
The copolymer of ethylene and other monomers preferably contains ethylene as a main component. Here, "containing ethylene as a main component" means that the copolymer contains 50 mol% or more, preferably 60 mol% or more of ethylene structural units.
Moreover, other monomers to be copolymerized with ethylene are not particularly limited as long as they are copolymerizable with ethylene.
Preferred examples of the ethylene polymer include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and polyethylene obtained by polymerization using a metallocene catalyst. Among these, it is particularly preferable to use linear low-density polyethylene (LLDPE) because of its high flexibility.

Among the above thermoplastic resins (A), styrene-based thermoplastic elastomers are preferred, and styrene-ethylene-butadiene-styrene block copolymers (SEBS) are more preferred, from the viewpoint of low dielectric properties and ease of processing.
Further, among the thermoplastic resins (A) exemplified above, particularly the thermoplastic resin (A) itself has a monofunctional (meth)acrylate (B) having a long-chain alkyl group, and a polyfunctional (meth)acrylate (C) When a combination that is difficult to react with is selected, a thermoplastic resin (A), a monofunctional (meth)acrylate having a long-chain alkyl group (B), and a polyfunctional (meth)acrylate (C) forms an interpenetrating polymer network structure (hereinafter, also referred to as a “semi-IPN structure”), which is thought to improve low dielectric properties and heat resistance. In the semi-IPN structure, a thermoplastic resin (A), a monofunctional (meth)acrylate having a long-chain alkyl group (B), and a polyfunctional (meth)acrylate (C) form a chemical bond rather than , the molecular chains of the thermoplastic resin (A), the monofunctional (meth)acrylate (B) having a long-chain alkyl group, and the polyfunctional (meth)acrylate (C) are partially and physically entangled with each other. Structure. By forming this semi-IPN structure, while maintaining the low dielectric properties of the thermoplastic resin (A), the crosslink density is artificially increased compared to the thermoplastic resin (A) alone. Therefore, it is considered that the elastic modulus is improved and the heat resistance is improved. From this point of view, among the above thermoplastic resins (A), styrene thermoplastic elastomers are preferred, and styrene-isobutylene-styrene-block copolymers (SIBS) or styrene-ethylene-butadiene-styrene block copolymers ( SEBS) is more preferred, and styrene-ethylene-butadiene-styrene block copolymer (SEBS) is even more preferred.

When a styrene-based thermoplastic elastomer is used as the thermoplastic resin (A), the styrene content is preferably 10% by mass or more, more preferably 15% by mass or more. Also, the styrene content is preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less, and even more preferably 40% by mass or less.
When the styrene content is within the above range, the thermoplastic resin (A) has a low dielectric loss tangent and an appropriate elastic modulus, so both low dielectric properties and heat resistance can be achieved, and handling properties are also good.

The thermoplastic resin (A) may be modified by known methods. Modified products include, for example, reaction products of the thermoplastic resin (A) exemplified above and at least one of unsaturated carboxylic acids and anhydrides thereof.
By modifying the thermoplastic resin (A), the polarity of the polymer is increased, so an improvement in adhesion to a metal layer such as a copper foil can be expected.

Examples of at least one of the unsaturated carboxylic acids and their anhydrides include acrylic acid, methacrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, itaconic acid, citraconic acid, Unsaturated carboxylic acids such as crotonic acid, isocrotonic acid, nadic acids, and anhydrides thereof can be mentioned.
Further, specific examples of acid anhydrides include maleic anhydride, citraconic anhydride, and nadic anhydrides.
As nadic acids or their anhydrides, endocis-bicyclo[2.2.1]hept-2,3-dicarboxylic acid (nadic acid), methyl-endocis-bicyclo[2.2.1]hept-5- ene-2,3-dicarboxylic acid (methyl nadic acid) and its anhydrides.

Among at least one of these unsaturated carboxylic acids and their anhydrides, acrylic acid, maleic acid, nadic acid, maleic anhydride, and nadic anhydride are preferred.
At least one of the unsaturated carboxylic acid and its anhydride may be used alone or in combination of two or more.

From the viewpoint of low dielectric properties, the content of the thermoplastic resin (A) in the composition is preferably 60% by mass or more, more preferably 70% by mass or more, and more preferably 80% by mass or more of the resin components of the composition. More preferably, 85% by mass or more is even more preferable. The upper limit of the content is not particularly limited, and the thermoplastic resin (A) alone (100% by mass) may be the resin component of the composition.
In the present invention, the "resin component" refers to the thermoplastic resin (A) contained in the present composition and other resins added as necessary.

The storage modulus of the thermoplastic resin (A) at 24°C is preferably 0.1 MPa or more, more preferably 1 MPa or more. The storage modulus is preferably less than 2000 MPa, more preferably less than 1500 MPa, still more preferably less than 1000 MPa, even more preferably less than 500 MPa, still more preferably less than 300 MPa, still more preferably less than 100 MPa, and even more preferably less than 50 MPa. preferable.
By setting the storage elastic modulus to be less than the above upper limit value, the resulting cured sheet material has good flexibility.
Further, by setting the storage elastic modulus to the above lower limit value or more, the heat resistance and handleability of the resulting cured sheet material are improved.

The storage elastic modulus is a value obtained by molding the thermoplastic resin (A) into a sheet having a thickness of 300 μm to obtain a test piece and measuring dynamic viscoelasticity with a viscoelastic spectrometer. The measurement conditions may be the same as those described in Examples.

The density of the thermoplastic resin (A) is preferably 0.98 g/cm ³ or less, more preferably 0.95 g/cm ³ or less, even more preferably 0.91 g/cm ³ or less. On the other hand, although the lower limit of the density is not particularly limited, it is preferably 0.80 g/cm ³ or more.
When the density is equal to or less than the above value, the resulting cured sheet material has good flexibility.

The density can be measured according to ASTM D792 using a test piece obtained by molding the thermoplastic resin (A) into a sheet having a thickness of 300 μm.

The dielectric loss tangent of the thermoplastic resin (A) is preferably less than 0.003, more preferably less than 0.002, even more preferably less than 0.001 at 10 GHz.
On the other hand, the lower limit is not particularly limited as long as it is 0 or more.
The smaller the dielectric loss tangent, the smaller the dielectric loss. Therefore, when the present composition is used as a circuit board material, the efficiency and speed of electric signal transmission can be increased.

The dielectric loss tangent is obtained by molding the thermoplastic resin (A) into a sheet having a thickness of 300 μm to obtain a test piece, and measuring it at a temperature of 23 ° C. and a frequency of 10 GHz in accordance with JIS C2565: 1992. .

2. Monofunctional (meth)acrylates (B) having long-chain alkyl groups, polyfunctional (meth)acrylates (C)
This composition contains a total of 1 monofunctional (meth)acrylate (B) having a long-chain alkyl group and a polyfunctional (meth)acrylate (C) per 100 parts by mass of the thermoplastic resin (A). It is preferable to contain more than 30 parts by mass and less than 30 parts by mass.
The total content of the monofunctional (meth)acrylate (B) having a long-chain alkyl group and the content of the polyfunctional (meth)acrylate (C) is 3 per 100 parts by mass of the thermoplastic resin (A). It is preferably from 5 parts by mass to 25 parts by mass, more preferably from 5 parts by mass to 20 parts by mass, and even more preferably from 10 parts by mass to 18 parts by mass.
When the total content of the monofunctional (meth)acrylate (B) having a long-chain alkyl group and the content of the polyfunctional (meth)acrylate (C) is within the above range, the thermoplastic resin (A) and The compatibility of the resin becomes good, and the crosslink density can be easily increased in a pseudo manner, so that the heat resistance of the resulting cured sheet material becomes good.

The mass ratio (B):(C) of the monofunctional (meth)acrylate (B) having a long-chain alkyl group and the polyfunctional (meth)acrylate (C) is preferably 50:50 to 99:1. :50 to 90:10 is more preferred, 50:50 to 80:20 is more preferred, and 50:50 to 70:30 is even more preferred.
When the mass ratio of the monofunctional (meth)acrylate (B) having a long-chain alkyl group and the polyfunctional (meth)acrylate (C) is within the above range, the compatibility with the thermoplastic resin (A) is Since the crosslink density can be easily increased in a pseudo manner, the heat resistance of the resulting cured sheet material is improved.

(1) Monofunctional (meth)acrylate (B) having a long-chain alkyl group
Examples of the monofunctional (meth)acrylate (B) having a long-chain alkyl group include CH ₂ ═C(R ¹ )COOR ² (wherein R ¹ is hydrogen or a methyl group, R ² has 8 to 25 carbon atoms, represents _{a linear ,} branched or cyclic alkyl group. ), preferably having a linear, branched or cyclic alkyl group with 8 or more and 25 or less carbon atoms. The number of carbon atoms is more preferably 10 or more, more preferably 12 or more, and even more preferably 15 or more. In addition, the carbon number is more preferably 20 or less.
Furthermore, as the monofunctional (meth)acrylate (B) having a long-chain alkyl group, a monofunctional (meth)acrylate having a branched long-chain alkyl group having 8 to 25 carbon atoms is preferable. The following monofunctional (meth)acrylates having a branched long-chain alkyl group are more preferred, and monofunctional (meth)acrylates having a branched long-chain alkyl group having 12 to 20 carbon atoms are most preferred.
When the carbon number of the alkyl group is within the above range, compatibility between the thermoplastic resin (A) and the polyfunctional (meth)acrylate (C) and the monofunctional (meth)acrylate (B) having a long-chain alkyl group is improved, and the molecular chains tend to entangle with each other during curing, so that the cross-linking density can be easily increased in a pseudo manner, and the heat resistance of the resulting cured sheet material is improved.

Specific examples of monofunctional (meth)acrylates (B) having long-chain alkyl groups include isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, and tridecyl (meth)acrylate. acrylates, stearyl (meth)acrylates, and isostearyl (meth)acrylates, among which isodecyl (meth)acrylates, lauryl (meth)acrylates, tridecyl (meth)acrylates, and isostearyl (meth)acrylates. At least one selected from the group consisting of isodecyl (meth)acrylate and isostearyl (meth)acrylate is more preferable, and isostearyl (meth)acrylate is most preferable.

The mass average molecular weight (Mw) of the monofunctional (meth)acrylate (B) having a long-chain alkyl group is preferably 100 or more and 4000 or less, more preferably 120 or more and 3000 or less, even more preferably 2000 or less, and even more preferably 1000 or less. Preferably, 800 or less is more preferable, and 600 or less is even more preferable.
When the mass average molecular weight (Mw) of the monofunctional (meth)acrylate (B) having a long-chain alkyl group is within the above range, the thermoplastic resin (A) and the monofunctional (meth)acrylate having a long-chain alkyl group can be cured at the time of curing. ) The molecular chains of the acrylate (B) and the polyfunctional (meth)acrylate (C) are easily entangled with each other, and the crosslink density is easily increased in a pseudo manner. Therefore, the heat resistance of the cured sheet obtained is improved.

The monofunctional (meth)acrylate (B) having a long-chain alkyl group has an ester group in its molecule, and it is preferable that the number of such polar functional groups is small.
Also, when having a long-chain alkyl group in which at least one hydrogen atom is substituted with a polar functional group, the number of polar functional groups is preferably small as well.
When the number of polar functional groups is small, the compatibility with the thermoplastic resin (A) and the polyfunctional (meth)acrylate (C) is improved, and the dielectric loss tangent of the resulting cured sheet product is also lowered.
A polar functional group means a functional group that has an electronegative atom (eg, nitrogen, oxygen, chlorine, fluorine, etc.) and has a net dipole. Examples thereof include an ester group, a carbonyl group, a carboxyl group, a hydroxy group, an amide group, an amino group and the like.
Polar functional group equivalent weight of monofunctional (meth)acrylate (B) having long-chain alkyl group (molecular weight of monofunctional (meth)acrylate (B) having long-chain alkyl group/molecular weight of polar functional group (multiple polar functional groups In some cases, the total amount)) is preferably 2 or more, more preferably 4 or more, and even more preferably 6 or more.

(2) Polyfunctional (meth)acrylate (C)
Polyfunctional (meth)acrylate (C) refers to bifunctional or higher (meth)acrylates, such as polyfunctional aliphatic (meth)acrylate compounds, polyfunctional alicyclic (meth)acrylate compounds, polyfunctional aromatic ( meth)acrylate compounds, polyfunctional heterocyclic (meth)acrylate compounds, and the like.

Polyfunctional aliphatic (meth)acrylate compounds, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentane Diol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate , 1,10-decanediol di(meth)acrylate, glycerin di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, ethoxylated 2-methyl-1,3-propanediol di(meth)acrylate, tri Methylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, ethoxylated propoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate , ethoxylated pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated propoxylated pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate , propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated propoxylated pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetraacrylate, and dipentaerythritol hexa(meth)acrylate.

Polyfunctional alicyclic (meth)acrylate compounds include, for example, cyclohexanedimethanol di(meth)acrylate, ethoxylated cyclohexanedimethanol di(meth)acrylate, propoxylated cyclohexanedimethanol di(meth)acrylate, ethoxylated propoxylated Cyclohexanedimethanol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, ethoxylated tricyclodecanedimethanol di(meth)acrylate, propoxylated tricyclodecanedimethanol di(meth)acrylate, ethoxylated propoxylated Tricyclodecane dimethanol di(meth)acrylate, ethoxylated hydrogenated bisphenol A di(meth)acrylate, propoxylated hydrogenated bisphenol A di(meth)acrylate, ethoxylated propoxylated hydrogenated bisphenol A di(meth)acrylate, ethoxy hydrogenated bisphenol F di(meth)acrylate, propoxylated hydrogenated bisphenol F di(meth)acrylate, ethoxylated propoxylated hydrogenated bisphenol F di(meth)acrylate, and the like.

Polyfunctional aromatic (meth)acrylate compounds include, for example, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, ethoxylated propoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol F Di(meth)acrylate, propoxylated bisphenol F di(meth)acrylate, ethoxylated propoxylated bisphenol F di(meth)acrylate, ethoxylated bisphenol AF di(meth)acrylate, propoxylated bisphenol AF di(meth)acrylate, ethoxylated Propoxylated bisphenol AF di(meth)acrylate, ethoxylated fluorene-type di(meth)acrylate, propoxylated fluorene-type di(meth)acrylate, ethoxylated propoxylated fluorene-type di(meth)acrylate, and the like.

Polyfunctional heterocyclic (meth)acrylate compounds include, for example, ethoxylated isocyanuric acid di(meth)acrylate, propoxylated isocyanuric acid di(meth)acrylate, ethoxylated propoxylated isocyanuric acid di(meth)acrylate, ethoxylated isocyanurate acid tri(meth)acrylate, propoxylated isocyanuric acid tri(meth)acrylate, and ethoxylated propoxylated isocyanuric acid tri(meth)acrylate, and the like.

Among the above, from the viewpoint of compatibility with the thermoplastic resin (A) and the monofunctional acrylate (B) having a long-chain alkyl group, a polyfunctional aliphatic (meth)acrylate compound and a polyfunctional alicyclic (meth) At least one selected from the group consisting of acrylate compounds is preferred.

The mass average molecular weight (Mw) of the polyfunctional (meth)acrylate (C) is preferably 100 or more and 4000 or less, more preferably 120 or more and 3000 or less, further preferably 120 or more and 2000 or less, and even more preferably 120 or more and 1000 or less, 120 or more and 800 or less are still more preferable, and 120 or more and 600 or less are still more preferable.
When the mass average molecular weight (Mw) of the polyfunctional (meth)acrylate (C) is within the above range, the thermoplastic resin (A), the monofunctional acrylate (B) having a long-chain alkyl group, and the polyfunctional acrylate (B) are formed during curing. The molecular chains of the functional (meth)acrylate (C) are easily entangled with each other, and the crosslink density is easily increased in a pseudo manner, so that the heat resistance of the resulting cured sheet material is improved.

The polyfunctional (meth)acrylate (C) has an ester group in the molecule, but it is preferable that the number of such polar functional groups is small.
Similarly, when the polyfunctional (meth)acrylate (C) has a polar functional group as a substituent, it is preferable that the number of polar functional groups is small.
When the number of polar functional groups is small, the compatibility with the thermoplastic resin (A) and the monofunctional acrylate (B) having a long-chain alkyl group is improved, and the dielectric loss tangent of the resulting cured sheet material is also lowered.
A polar functional group means a functional group that has an electronegative atom (eg, nitrogen, oxygen, chlorine, fluorine, etc.) and has a net dipole. Examples thereof include an ester group, a carbonyl group, a carboxyl group, a hydroxy group, an amide group, an amino group and the like.
The polar functional group equivalent of the polyfunctional (meth)acrylate (C) (molecular weight of the polyfunctional (meth)acrylate (C)/molecular weight of the polar functional group (when there are multiple polar functional groups, the total amount thereof)) is 1. 5 or more is preferable, 1.8 or more is more preferable, 2 or more is more preferable, 2.5 or more is still more preferable, and 3 or more is still more preferable.

3. Organic peroxide (D)
The composition may contain an organic peroxide (D) for the purpose of accelerating the curing reaction.
Examples of the organic peroxides include those included in the group of hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters and ketone peroxides.
Specifically, hydroperoxides such as cumene hydroperoxide and tert-butyl hydroperoxide; dialkyl peroxides such as oxy)hexane and 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne; diacyl peroxides such as lauryl peroxide and benzoyl peroxide; tert-butylperoxy peroxyesters such as acetate, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate; and ketone peroxides such as cyclohexanone peroxide.

The content of the organic peroxide (D) in the present composition is preferably 0.01 parts by mass or more and 5 parts by mass or less, and 0.05 parts by mass or more and 3 parts by mass with respect to 100 parts by mass of the thermoplastic resin (A). The following is more preferable, and 0.1 parts by mass or more and 1 part by mass or less is even more preferable.
When the content of the organic peroxide (D) is within the above range, it is possible to maintain low dielectric properties of the cured sheet while accelerating the curing reaction.

4. Solvent (E)
When manufacturing a resin sheet from this composition through a coating process, the solvent (E) may be contained.
The solvent (E) is one in which the thermoplastic resin (A), the monofunctional (meth)acrylate (B) having a long-chain alkyl group, and the polyfunctional (meth)acrylate (C) can be uniformly dissolved. Examples include, but are not limited to, toluene, cyclohexane, tetrahydrofuran, and xylene.

The solvent (E) preferably has a boiling point of 200° C. or lower so as to volatilize when the resin sheet is dried.

The content of the solvent (E) in the present composition is preferably 100 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin (A) from the viewpoint of film-forming properties, and 200 parts by mass or more and 400 parts by mass. The following are more preferred.

5. Other components This composition contains, as components other than the above, a thermoplastic elastomer other than the thermoplastic resin (A), a monofunctional (meth)acrylate (B) having a long-chain alkyl group, and a polyfunctional (meth)acrylate (C ) other than cross-linking agents, ultraviolet absorbers, antistatic agents, antioxidants, coupling agents, plasticizers, flame retardants, colorants, dispersants, emulsifiers, elastic softening agents, diluents, antifoaming agents, ion traps agents, thickeners, leveling agents, inorganic particles, organic particles, and the like.

Examples of crosslinking agents other than monofunctional (meth)acrylates (B) and polyfunctional (meth)acrylates (C) having long-chain alkyl groups include bismaleimide compounds and epoxy compounds.

Examples of inorganic particles include calcium carbonate, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, zinc oxide, magnesium oxide, calcium oxide, titanium oxide, aluminum oxide, zinc oxide, alumina, aluminum hydroxide, hydroxyl Apatite, silica, magnesium silicate, mica, talc, kaolin, clay, glass powder, asbestos powder, zeolite, silicate clay and the like.
Examples of organic particles include (meth)acrylate-based resin particles, styrene-based resin particles, silicone-based resin particles, nylon-based resin particles, polyethylene-based resin particles, benzoguanamine-based resin particles, and urethane-based resin particles.
When inorganic particles or organic particles are contained, the content is preferably 1 part by mass or more and 80 parts by mass or less, more preferably 5 parts by mass or more and 75 parts by mass or less, relative to 100 parts by mass of the resin component of the present composition. More preferably 10 parts by mass or more and 70 parts by mass or less. When the content of the inorganic particles or organic particles is at least the above lower limit, the dielectric properties of the cured sheet can be further reduced, and the coefficient of linear thermal expansion of the cured sheet can be reduced. Detachment from the substrate is less likely to occur. On the other hand, when the content of the inorganic particles or the organic particles is equal to or less than the above upper limit, the formability of the cured sheet material is improved.

<Resin sheet>
A resin sheet according to one embodiment of the present invention (hereinafter also referred to as "this resin sheet") is obtained by molding the present composition in an uncured state into a sheet shape.

The thickness of the resin sheet after curing is preferably 10 to 500 μm, more preferably 50 to 400 μm, even more preferably 100 to 350 μm.
When the thickness of the present resin sheet after curing is at least the above lower limit, the handling property is improved. Further, when the thickness is equal to or less than the above upper limit, when the present resin sheet is used as a circuit board material, followability to a step of the board is improved.
The above thickness is a value obtained by measuring a cured product obtained by hot-pressing the resin sheet under conditions of 200° C. and 0.2 MPa for 30 minutes with a micrometer.

The dielectric constant of the resin sheet after curing is preferably 4 or less, more preferably 3 or less, and even more preferably 2.5 or less. On the other hand, the lower limit of the dielectric constant is not particularly limited as long as it is 1 or more.
In addition, the dielectric loss tangent of the resin sheet after curing is preferably 0.003 or less, more preferably 0.002 or less, and even more preferably 0.0015 or less. On the other hand, the lower limit of the dielectric loss tangent is not particularly limited as long as it is 0 or more.
The relative dielectric constant and dielectric loss tangent are measured at a temperature of 23 in accordance with JIS C2565: 1992 using a cured product obtained by heat-pressing the resin sheet for 30 minutes at 200 ° C. and 0.2 MPa. °C and a frequency of 10 GHz.

The storage elastic modulus (24° C.) of the present resin sheet after curing is preferably 1 MPa or higher, more preferably 2 MPa or higher, and even more preferably 3 MPa or higher, from the viewpoint of handleability. Further, when the present resin sheet is used as a circuit board material, the storage elastic modulus (24° C.) is preferably 1000 MPa or less, more preferably 500 MPa or less, and more preferably 300 MPa or less from the viewpoint of the followability to the step of the substrate. More preferred.
From the viewpoint of heat resistance, the storage elastic modulus (200° C.) of the resin sheet after curing is preferably 0.01 MPa or more, more preferably 0.05 MPa or more, and even more preferably 0.1 MPa or more. Although the upper limit of the storage modulus (200° C.) is not particularly limited, it is preferably 10 MPa or less, more preferably 5 MPa or less.
The storage elastic modulus is a value obtained by measuring the dynamic viscoelasticity of a cured product obtained by hot-pressing the resin sheet under conditions of 200° C. and 0.2 MPa for 30 minutes as a test piece. be.

The heat resistance temperature of the resin sheet after curing is preferably 200° C. or higher and 500° C. or lower from the viewpoint of heat resistance when mounted on a device.
The above heat resistance temperature is obtained by measuring the dynamic viscoelasticity of a cured product obtained by hot-pressing the resin sheet for 30 minutes at 200 ° C. and 0.2 MPa. , is the value obtained by reading the temperature just before the viscous liquid state from the rubbery plateau region.

<Laminate>
In order to improve handleability, the present resin sheet is preferably formed into a laminate by providing a release film on one or both surfaces thereof.
As the release film, for example, a resin film containing polyolefin such as polyethylene and polypropylene; polyester such as polyethylene terephthalate and polyethylene naphthalate; polyimide; and polycarbonate as a main component can be used. A silicone resin release agent or the like may be applied to these surfaces to adjust the peel strength.
The thickness of the release film is preferably 1 to 300 μm, more preferably 5 to 200 μm, even more preferably 10 to 150 μm, even more preferably 20 to 120 μm.
The release film may be subjected to matte treatment, corona treatment, or antistatic treatment on the surface that comes into contact with the resin sheet.

The laminate may be wound around a core to form a wound body.
In the wound body according to one embodiment of the present invention, the length of the laminate is preferably 10 m or longer, more preferably 20 m or longer. Since the length of the laminate is 10 m or more, for example, when the present resin sheet is used as a flexible laminate or a stretchable laminate, it is possible to continuously produce electronic members, and it is excellent in continuous film formability. . In addition, although the upper limit of the said length is not specifically limited, 1000 m or less is preferable.
The material of the core is not particularly limited, but examples thereof include paper, resin-impregnated paper, acrylonitrile/butadiene/styrene copolymer (ABS resin), fiber reinforced plastic (FRP), phenolic resin, and inorganic-containing resin. An adhesive may be used for the core.

<Method for manufacturing resin sheet>
The method for producing the present resin sheet will be described below, but the method for producing the present resin sheet is not limited to the following method.

[First manufacturing method]
A first method for producing the present resin sheet includes a coating liquid preparation step of preparing a coating liquid composed of a resin composition, and a forming step of forming the coating liquid into a sheet shape.

(1) Coating solution preparation step In the coating solution preparation step, a thermoplastic resin (A), a monofunctional (meth)acrylate having a long-chain alkyl group (B), a polyfunctional (meth)acrylate (C) and, if necessary, The organic peroxide (D), the solvent (E) and other components that are added according to need are stirred and uniformly mixed to obtain a coating liquid.
For mixing, for example, a general mixing/stirring device such as a mixer, blender, three-roll kneading device, ball mill, kneader, single-screw kneader or twin-screw kneader can be used. May be heated accordingly.

(2) Forming Step In the forming step, the coating liquid is formed into a sheet to obtain a resin sheet.
A known method can be used as a method for forming the coating liquid into a sheet. For example, a doctor blade method, a solvent casting method, an extrusion film forming method, or the like may be used. Preferred molding methods include a method including (2-1) a coating step and (2-2) a drying step shown below.

(2-1) Coating Step In the coating step, a coating liquid is applied to the surface of the release film to form a coating film.
The coating method may be a general method such as a dipping method, a spin coating method, a spray coating method, or a blade method. A coating device such as a spin coater, a slit coater, a die coater, a blade coater, etc. can be used for coating, whereby a coating film having a predetermined thickness can be uniformly formed on the release film. .

(2-2) Drying Step In the drying step, the solvent is removed from the coating film formed above.
Although the drying temperature is not particularly limited, it is usually 10 to 150°C, preferably 25 to 120°C, more preferably 30 to 110°C. When the drying temperature is equal to or lower than the above upper limit, the cross-linking reaction of the monofunctional (meth)acrylate (B) and polyfunctional (meth)acrylate (C) having long-chain alkyl groups in the coating film is suppressed. Moreover, since the drying temperature is equal to or higher than the above lower limit, foaming of the resin sheet can be suppressed, the solvent can be effectively removed, and productivity is improved.
The drying time can be appropriately adjusted according to the state of the coating film, the drying environment, and the like. The drying time is preferably 1 minute or longer, more preferably 2 minutes or longer, even more preferably 5 minutes or longer, even more preferably 10 minutes or longer, particularly preferably 20 minutes or longer, and most preferably 30 minutes or longer. On the other hand, the drying time is preferably 4 hours or less, more preferably 3 hours or less, still more preferably 2 hours or less.
When the drying time is equal to or longer than the above lower limit, the solvent can be sufficiently removed. Productivity improves and manufacturing cost can be suppressed because drying time is below the said upper limit.
The solvent in the resin composition can be removed by a known heating method such as a hot plate, hot air oven, IR heating oven, vacuum dryer, and high frequency heater.

From the viewpoint of preventing contamination of the surface of the resin sheet and ease of handling, a release film may be laminated on the resin sheet after the drying step.

[Second manufacturing method]
A second method for producing the present resin sheet includes a film-forming step of extruding the resin composition onto a release film.

In the film forming process, a thermoplastic resin (A), a monofunctional (meth)acrylate having a long-chain alkyl group (B), a polyfunctional (meth)acrylate (C) and an organic peroxide ( D) and other components are kneaded with a single-screw extruder or twin-screw extruder, and the melting point of the thermoplastic resin (A) or higher and a monofunctional (meth) acrylate (B) having a long-chain alkyl group and a poly( Under temperature conditions below the cross-linking temperature of the functional (meth)acrylate (C), it is extruded onto a release film using an extruder or the like to form a film. The method of extruding the resin composition is not particularly limited, but a more specific example is T-die molding.

<Sheet cured product>
A sheet cured product (hereinafter also referred to as “main cured product”) according to one embodiment of the present invention is obtained by curing the resin sheet.

The curing temperature of the resin sheet is such that the thermoplastic resin (A) does not flow, and the cross-linking reaction of the monofunctional (meth)acrylate (B) having a long-chain alkyl group and the polyfunctional (meth)acrylate (C) does not occur. Any temperature can be used as long as it progresses. Specifically, the temperature is preferably 120 to 300°C, more preferably 140 to 250°C, and even more preferably 150 to 220°C.
The curing time of the resin sheet is not particularly limited, but preferably 10 minutes to 1 hour.

<Applications of Resin Composition, Resin Sheet and Sheet Cured Material>
Applications of the resin composition, resin sheet, and cured sheet of the resin sheet of the present invention include, for example, copper foil laminates, stretchable substrates, flexible printed substrates, multilayer printed wiring substrates, capacitors, and other electric and electronic devices. Circuit board materials, underfill materials, 3D-LSI inter-chip fills, insulating sheets, damping materials, adhesives, solder resists, semiconductor sealing materials, hole-filling resins, component-embedding resins, etc., but are not limited to these. not something.

<Circuit board material>
The resin sheet according to one embodiment of the present invention can be used as a circuit board material by laminating it with a conductor.

As the conductor, a metal foil made of a conductive metal such as copper or aluminum, an alloy containing these metals, or a metal layer formed by plating or sputtering can be used.

When used as a circuit board material for electric/electronic equipment, the thickness of the resin sheet is preferably 10 μm or more and 500 μm or less. Moreover, the thickness of the conductor is preferably 0.2 μm or more and 70 μm or less.

<Method for producing circuit board material>
The circuit board material in the present invention can be produced, for example, by the following method.
After laminating the resin sheet according to one embodiment of the present invention to the conductor, the resin sheet is thermally cured to form an insulating layer. Additional conductors are deposited over the insulating layer, with as many such layers as required.
The curing temperature of the resin sheet is such that the thermoplastic resin (A) does not flow and the cross-linking reaction of the monofunctional (meth)acrylate (B) and the polyfunctional (meth)acrylate (C) having long-chain alkyl groups proceeds. Any temperature will do. Specifically, the curing temperature of the resin sheet is preferably 120 to 300°C, more preferably 140 to 250°C, even more preferably 150 to 220°C.
The curing time of the resin sheet is not particularly limited, but preferably 10 minutes to 1 hour.
The lamination of the resin sheet and the conductor may be performed by directly superimposing the conductive metal foil on the resin sheet, or by bonding the resin sheet and the conductive metal foil with an adhesive. Alternatively, a method of forming a conductive metal layer by plating or sputtering may be used, or a combination of these methods may be used.
Further, the method may include a step of drilling holes in the cured product layer to form via holes, and a step of roughening the surface of the cured product layer.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples. In addition, in the following examples and comparative examples, various physical properties were measured by the following methods.

<raw materials>
[Thermoplastic resin (A)]
・a-1: Styrene-ethylene-butadiene-styrene block copolymer (SEBS: Asahi Kasei Co., Ltd., "Tuftec H1052"), styrene content 20% by mass, storage modulus (24 ° C.) = 6.2 MPa, density = 890g/ ^cm3

[Monofunctional (meth)acrylate (B) having a long-chain alkyl group]
· b-1: Isostearyl acrylate (ISA: Shin-Nakamura Chemical Co., Ltd., "NK Ester S-1800ALC"), mass average molecular weight (Mw): 324.5, polar functional group (ester group) equivalent: 7.38
· b-101: methyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), mass average molecular weight (Mw): 86.09, polar functional group (ester group) equivalent: 1.96

[Polyfunctional (meth)acrylate (C)]
· c-1: Tetramethylolmethane tetraacrylate (TMMT: Shin-Nakamura Chemical Co., Ltd., "NK Ester A-TMMT"), mass average molecular weight (Mw): 352.34, polar functional group (ester group) equivalent: 2 .00
· c-2: tricyclodecane dimethanol diacrylate (A-DCP: manufactured by Shin-Nakamura Chemical Co., Ltd., "NK Ester A-DCP"), weight average molecular weight (Mw): 336.48, polar functional group (ester group ) Equivalent weight: 3.82

[Organic peroxide (D)]
・d-1: 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne (manufactured by NOF CORPORATION)

[Solvent (E)]
・ e-1: toluene (content > 99.0% by mass)

<Example 1>
Raw materials were blended in the proportions shown in Table 1 and heated at about 80° C. to completely dissolve the raw materials to prepare a resin composition. The prepared resin composition was spread in the form of a sheet on the release-treated surface of a 50 μm-thick release film (PET film manufactured by Mitsubishi Chemical Corporation) that had been subjected to silicone release treatment, to obtain a resin sheet. The thickness of the resin sheet was adjusted so that the thickness of the sheet after curing was about 300 μm.
After drying the resin sheet developed on the release film in an oven at 100° C. for 1 hour, a release film (Mitsubishi Chemical Co., Ltd. PET film) having a thickness of 50 μm that has been subjected to silicone release treatment is removed from the resin sheet. A laminate was formed by laminating such that the mold-treated surface was on the resin sheet side. The laminate was held in a hot press at 200° C. for 30 minutes while applying a pressure of about 0.2 MPa to completely cure the resin sheet, and the release films on both sides were peeled off to obtain a cured sheet. Dielectric properties, storage elastic modulus and heat resistance temperature of the cured sheet were evaluated.

<Example 2, Comparative Examples 1 to 4>
A sheet cured product was produced in the same manner as in Example 1, except that the raw materials were blended according to the ratios shown in Table 1. Dielectric properties, storage elastic modulus and heat resistance temperature of the cured sheet were evaluated.

<Measurement method>
(1) Dielectric Properties The in-plane dielectric constant and dielectric loss tangent of the cured sheet were measured in TE mode using a cavity resonator (manufactured by AET) and a network analyzer MS46 122B (manufactured by Anritsu). The measurement frequency was 10 GHz.

(2) Storage Elastic Modulus and Heat Resistant Temperature The dynamic viscoelasticity of the cured sheet was measured using a viscoelasticity spectrometer DVA-200 (manufactured by IT Keisoku Co., Ltd.) under the following conditions. From the measurement results, the values of the storage elastic modulus at 24° C. and 200° C. were taken as the storage elastic modulus of each cured sheet material.
In the obtained dynamic viscoelasticity graph, the temperature immediately before the rubber-like flat region changed to the viscous liquid state was defined as the heat resistant temperature of each sheet.
[Measurement condition]
Vibration frequency: 10Hz
Strain: 0.1%
Heating rate: 3°C/min Measurement temperature: -100°C to 300°C

From Examples 1 and 2 and Comparative Example 2, a monofunctional (meth)acrylate (B) having a long-chain alkyl group and a polyfunctional (meth)acrylate (C) are added to the thermoplastic resin (A). It was shown that heat resistance can be improved while maintaining low dielectric properties.

Further, from Examples 1 and 2 and Comparative Examples 3 and 4, the total content of monofunctional (meth)acrylate (B) having a long-chain alkyl group and polyfunctional (meth)acrylate (C) is thermoplastic resin (A) It was shown that when the content is 30 parts by mass or more with respect to 100 parts by mass, the heat resistance is lowered.
This is because when the total content of the monofunctional (meth)acrylate (B) having a long-chain alkyl group and the polyfunctional (meth)acrylate (C) increases, the compatibility with the thermoplastic resin (A) deteriorates. Therefore, it is considered that it was difficult to obtain the effect of increasing the crosslink density in a pseudo manner.

The number of polar functional groups in the molecule of the polyfunctional (meth)acrylate (C) is smaller than in Examples 1 and 2, that is, the polar functional group equivalent of the polyfunctional (meth)acrylate (C) (molecular weight of (C)/polarity It was shown that the higher the molecular weight of the functional group, the lower the dielectric loss tangent.

In the above examples, there is no example of using an olefinic thermoplastic elastomer or an ethylene polymer as the thermoplastic resin (A), but the thermoplastic resin (A) and a monofunctional (meta) From the mechanism that the heat resistance can be improved by entangling the molecular chains of the acrylate (B) and the polyfunctional (meth)acrylate (C), the same effect as that of the styrene-based thermoplastic elastomer can be expected. can.

Claims (10)

At least one thermoplastic resin (A) selected from the group consisting of styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers and ethylene-based polymers, and a monofunctional (meth)acrylate (B) having a long-chain alkyl group. , a polyfunctional (meth)acrylate (C), and
The total content of the monofunctional (meth)acrylate (B) having a long-chain alkyl group and the polyfunctional (meth)acrylate (C) with respect to 100 parts by mass of the thermoplastic resin (A) is 1 part by mass or more and 30 parts by mass The resin composition, which is less than 1 part. The resin composition according to claim 1, comprising a styrene-based thermoplastic elastomer as the thermoplastic resin (A). The resin composition according to claim 1, wherein the styrene content of the styrene-based thermoplastic elastomer is 10% by mass or more and 70% by mass or less. The mass ratio (B):(C) of the monofunctional (meth)acrylate (B) having a long-chain alkyl group and the polyfunctional (meth)acrylate (C) is 50:50 to 99:1, The resin composition according to claim 1. The polar functional group equivalent of the monofunctional (meth)acrylate (B) having a long-chain alkyl group (molecular weight of the monofunctional (meth)acrylate (B) having a long-chain alkyl group/molecular weight of the polar functional group) is 2 or more. The resin composition of claim 1, wherein 2. The resin composition according to claim 1, wherein the polyfunctional (meth)acrylate (C) has a polar functional group equivalent (molecular weight of polyfunctional (meth)acrylate (C)/molecular weight of polar functional group) of 1.5 or more. thing. A resin sheet made of the resin composition according to any one of claims 1 to 6. A laminate comprising a release film on one or both surfaces of the resin sheet according to claim 7 . A sheet cured product obtained by curing the resin sheet according to claim 7 . A circuit board material obtained by laminating an insulating layer made of the resin sheet according to claim 7 and a conductor.