JP2017002134A - Low-dielectric resin composition and low-dielectric cured product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-dielectric resin composition which contains an epoxy resin and a (meth)acrylate copolymer having a low dielectric constant and excellent compatibility with epoxy resins.SOLUTION: The low-dielectric resin composition contains (A) an epoxy resin and (B) a (meth)acrylate copolymer obtained by copolymerizing glycidyl (meth)acrylate, an alkyl (meth)acrylate, and an aromatic vinyl compound. The (meth)acrylate copolymer (B) has a weight-average molecular weight of 5,000-1,000,000 and a dielectric constant of 3.0 or less.SELECTED DRAWING: None

Description

The present invention relates to a low dielectric resin composition and a low dielectric cured product.

Epoxy resin compositions are widely used in various fields such as sealing materials for electrical and electronic parts, matrix materials for various structural members, adhesives, etc. due to their excellent adhesion and electrical / mechanical properties. Further, by adding various additives, preferred properties are imparted according to the application. For example, when the epoxy resin composition is a cured product, it has been known that it becomes rigid due to its high elastic modulus, and stress is easily applied to the peripheral members due to thermal expansion and curing shrinkage. Therefore, an attempt has been made to lower the elastic modulus by blending an epoxy resin composition with a rubber component such as silicone or acrylic rubber ((meth) acrylic acid ester copolymer or the like) depending on the application. For example, Patent Document 1 discloses a resin composition in which terminal carboxyl-modified acrylonitrile butadiene rubber (CTBN) is blended with a bisphenol A type epoxy resin.

However, since CTBN has a high dielectric constant of 6 or more, problems such as propagation delay and transmission loss have occurred when the resin composition of Patent Document 1 is used in electronic equipment in the field of information communication. Therefore, development of a rubber component having a low dielectric constant instead of CTBN has been demanded for the purpose of shortening propagation delay and reducing transmission loss.

JP-A-8-217857

An object of the present invention is to provide a low dielectric resin composition comprising a (meth) acrylic acid ester copolymer having a low dielectric constant and excellent compatibility with an epoxy resin, and the epoxy resin.

As a result of intensive studies to solve the above problems, the present inventors have found that a (meth) acrylic acid ester copolymer obtained by copolymerizing a specific monomer component has a low dielectric constant and a phase with an epoxy resin. The present invention was completed by finding that it has excellent solubility.

That is, the low dielectric resin composition of the present invention is
Low dielectric resin containing (A) epoxy resin and (B) glycidyl (meth) acrylate, alkyl (meth) acrylate and (meth) acrylic acid ester copolymer obtained by copolymerizing aromatic vinyl compound A composition comprising:
The (B) (meth) acrylic acid ester copolymer has a weight average molecular weight of 5,000 to 1,000,000 and a dielectric constant of 3.0 or less.

In the low dielectric resin composition of the present invention, the alkyl group of the alkyl (meth) acrylate preferably has 2 to 18 carbon atoms.

In the low dielectric resin composition of the present invention, the weight ratio of the monomer component in the (B) (meth) acrylic ester copolymer is glycidyl (meth) acrylate: alkyl (meth) acrylate: aromatic vinyl compound = 1 to 1. It is preferable that it is 15%: 25-98%: 1-60%.

In the low dielectric resin composition of the present invention, the (B) (meth) acrylic acid ester copolymer preferably has a ratio of the weight average molecular weight to the number average molecular weight of 4 or less.

In the low dielectric resin composition of the present invention, (A) the epoxy resin is bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolak type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy. It is preferably at least one selected from the group consisting of a resin and a dicyclopentadiene type epoxy resin.

The low dielectric resin composition of the present invention further includes (C) a curing agent, and (B) (meth) acrylic acid ester with respect to a total of 100 parts by weight of (A) epoxy resin and (C) curing agent. It is preferable to contain 10 to 75 parts by weight of a copolymer.

The low dielectric cured product of the present invention is a low dielectric cured product obtained by curing the low dielectric resin composition of the present invention,
(A) It has a sea-island structure consisting of a sea part containing an epoxy resin and an island part containing (B) a (meth) acrylic acid ester copolymer,
(B) The major axis of the island part containing the (meth) acrylic acid ester copolymer is 0.1 to 10 μm.

The cover lay film of the present invention is characterized in that the low dielectric resin composition of the present invention is applied to at least one surface of the film.

The bonding sheet of the present invention is characterized in that the low dielectric resin composition of the present invention is applied to at least one surface of a film.

The prepreg of the present invention is characterized in that the low dielectric resin composition of the present invention is impregnated in a woven fabric or a non-woven fabric.

The laminated board for printed wiring boards of the present invention is characterized in that a metal foil is laminated on one side or both sides of the prepreg of the present invention.

The low dielectric resin composition object of the present invention contains a (meth) acrylate ester copolymer obtained by polymerizing a specific monomer component and having a low dielectric constant and excellent compatibility with an epoxy resin. When used in equipment, propagation delay is shortened and transmission loss is reduced.

<< Low dielectric resin composition >>
The low dielectric resin composition of the present invention is
Low dielectric resin containing (A) epoxy resin and (B) glycidyl (meth) acrylate, alkyl (meth) acrylate and (meth) acrylic acid ester copolymer obtained by copolymerizing aromatic vinyl compound A composition comprising:
The (B) (meth) acrylic acid ester copolymer has a weight average molecular weight of 5,000 to 1,000,000 and a dielectric constant of 3.0 or less.

<(A) Epoxy resin>
(A) The epoxy resin is not particularly limited. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin, cresol novolak type epoxy resin. , Alicyclic epoxy resin, aliphatic chain epoxy resin, biphenyl type epoxy resin, biphenol type epoxy resin, aralkyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, trishydroxyphenylmethane type epoxy compound, bisphenol Diglycidyl etherified product, naphthalenediol diglycidyl etherified product, phenolic diglycidyl etherified product, alcohol diglycidyl etherified product, Li triglycidyl isocyanurate, various glycidyl ether type epoxy resin, glycidyl amine type epoxy resin, glycidyl ester type epoxy resin, oxidized epoxy resins, such as phosphorus-modified epoxy resin. These may be used alone or in combination of two or more. Among these epoxy resins, from the viewpoint of heat resistance, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, and dicyclo It is preferable to use at least one selected from the group consisting of pentadiene type epoxy resins.

<(B) (Meth) acrylic acid ester copolymer>
(B) (meth) acrylic acid ester copolymer is a (meth) acrylic acid ester copolymer obtained by copolymerizing glycidyl (meth) acrylate, alkyl (meth) acrylate and aromatic vinyl compound, The weight average molecular weight is 5,000 to 1,000,000, and the dielectric constant is 3.0 or less.
In this specification, acrylic acid and methacrylic acid may be combined and described as (meth) acrylic acid, or acrylate and methacrylate may be combined and described as (meth) acrylate.

First, the monomer component will be described.
As glycidyl (meth) acrylate, glycidyl acrylate or glycidyl methacrylate can be used. These may be used alone or in combination of two or more.

The alkyl group of the alkyl (meth) acrylate may be linear or branched. Although it does not specifically limit as alkyl (meth) acrylate, For example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) ) Acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like. . These alkyl (meth) acrylates may be used alone or in combination of two or more.

Although carbon number of the alkyl group of alkyl (meth) acrylate is not specifically limited, It is preferable that it is 2-18, and it is more preferable that it is 5-18. When the carbon number of the alkyl group is less than 2, the dielectric constant may increase, and when it exceeds 18, the solvent may become insoluble in the solvent.

(B) Since the (meth) acrylic acid ester copolymer is obtained by copolymerizing an aromatic vinyl compound as a monomer component, it has a low dielectric constant and is excellent in compatibility with (A) an epoxy resin. . The aromatic vinyl compound is not particularly limited. For example, styrene, α-methylstyrene, α-ethylstyrene, α-propylstyrene, α-isopropylstyrene, α-t-butylstyrene, 2-methylstyrene, 3-methylstyrene, Examples include methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, vinyltoluene and the like. These may be used alone or in combination of two or more.

(B) The (meth) acrylic acid ester copolymer may be obtained by arbitrarily copolymerizing other monomer components in addition to glycidyl (meth) acrylate, alkyl (meth) acrylate and aromatic vinyl compound. good. Although it does not specifically limit as another monomer component, For example, carboxyl group containing monomers, such as (meth) acrylic acid, (beta) -carboxyethyl acrylate, itaconic acid, crotonic acid, maleic acid, fumaric acid, maleic anhydride; cyclohexyl ( Aliphatic ester group-containing monomers other than alkyl groups such as meth) acrylate and isobornyl (meth) acrylate; Aromatic ester group-containing monomers such as phenyl (meth) acrylate and benzyl (meth) acrylate; 2-hydroxyethyl (meth) acrylate , 4-hydroxybutyl (meth) acrylate, chloro-2-hydroxypropyl acrylate, diethylene glycol mono (meth) acrylate, hydroxyl group-containing monomers such as allyl alcohol; aminomethyl (meth) acrylate Amino group-containing monomers such as dimethylaminoethyl (meth) acrylate; amide group-containing monomers such as acrylamide, methylol (meth) acrylamide, methoxyethyl (meth) acrylamide; alkoxy group-containing monomers such as methacryloxypropylmethoxysilane; acetoacetoxyethyl Examples include acetoacetyl group-containing monomers such as (meth) acrylate; vinyl monomers other than styrene such as vinyl acetate and vinyl chloride; (meth) acrylonitrile and the like. These may be used alone or in combination of two or more.

(B) Although the weight ratio of the monomer component in the (meth) acrylic acid ester copolymer is not particularly limited, glycidyl (meth) acrylate: alkyl (meth) acrylate: aromatic vinyl compound = 1-15%: 25-98 %: 1 to 60% is preferable, and 1 to 10%: 30 to 50%: 40 to 60% is more preferable.
If the weight ratio of glycidyl (meth) acrylate is less than 1%, the adhesion may not be sufficiently improved, and if it exceeds 15%, the flexibility may be lost, resulting in a decrease in adhesion. When the weight ratio of the alkyl (meth) acrylate is less than 25%, flexibility may be lost, and when it exceeds 98%, the adhesion may be lowered. If the weight ratio of the aromatic vinyl compound is less than 1%, the low dielectric property may not be sufficiently maintained, and if it exceeds 60%, flexibility may be lost.

The epoxy value of the (B) (meth) acrylic acid ester copolymer is not particularly limited, but is preferably 0.06 to 1.2 eq / kg, and more preferably 0.1 to 0.8 eq / kg. More preferably, it is more preferably 0.2 to 0.7 eq / kg. If the epoxy value is less than 0.06 eq / kg, the adhesion may not be sufficiently improved, and if it exceeds 1.2 eq / kg, the flexibility may be lost, resulting in a decrease in adhesion.

The weight average molecular weight (Mw) of the (B) (meth) acrylic acid ester copolymer is not particularly limited as long as it is 5,000 to 1,000,000, but is preferably 5,000 to 500,000. More preferably, it is 5,000-100,000. When the weight average molecular weight is less than 5,000, the heat-resistant adhesion property may be deteriorated, and when it exceeds 1,000,000, it may become insoluble in a solvent and may be difficult to handle. In this invention, a weight average molecular weight means the weight average molecular weight of styrene conversion measured by gel permeation chromatography (GPC).

(B) The ratio (Mw / Mn) (dispersion degree) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the (meth) acrylic acid ester copolymer is not particularly limited, but is 4 or less. Is preferable, and 3 or less is more preferable. When the ratio of the weight average molecular weight to the number average molecular weight exceeds 4, the heat resistant adhesion may be lowered.

The dielectric constant of (B) (meth) acrylic acid ester copolymer is not particularly limited as long as it is 3.0 or less. If the dielectric constant exceeds 3.0, the dielectric constant of the cured product cannot be lowered sufficiently.

(B) Although the glass transition temperature (Tg) of a (meth) acrylic acid ester copolymer is not specifically limited, It is preferable that it is -40-40 degreeC, and it is more preferable that it is -20-20 degreeC. If the glass transition temperature is less than −40 ° C., tack may appear or handling properties may be significantly reduced, and if it exceeds 40 ° C., flexibility may be lost, resulting in lower adhesion. .

(B) The polymerization method of the (meth) acrylic acid ester copolymer is not particularly limited, and a conventionally known polymerization method can be adopted, but from the viewpoint of lowering the ratio between the weight average molecular weight and the number average molecular weight. Is preferably suspension polymerization.

When dispersing the monomer component in the dispersion medium, a dispersant may be added as necessary. The dispersant is not particularly limited, but water-soluble polymers such as polyvinylpyrrolidone, polyvinyl alcohol, (meth) acrylate, polyacrylamide, partially saponified polyacrylamide, carboxymethylcellulose, methylcellulose, ethylcellulose, calcium phosphates, calcium carbonate And inorganic salt powders. These may be used alone or in combination of two or more.

As the radical polymerization initiator, those in which the polymerization initiation radical species after decomposition are oil-soluble are preferred. Examples of such radical polymerization initiators include 2,2′-azobispropane, 2,2′-dichloro-2,2′-azobispropane, 1,1′-azo (methylethyl) diacetate, 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2′-azobis (2-aminopropane) nitrate, 2,2′-azobisisobutane, 2,2′-azobisisobutyramide, 2, 2′-azobisisobutyronitrile, methyl 2,2′-azobis-2-methylpropionate, 2,2′-dichloro-2,2′-azobisbutane, 2,2′-azobis-2-methylbutyro Nitrile, dimethyl 2,2′-azobisisobutyrate, 1,1′-azobis (sodium 1-methylbutyronitrile-3-sulfonate), 2- (4-methylphenylazo) -2-methylmalo Dinitrile 4,4′-azobis-4-cyanovaleric acid, 3,5-dihydroxymethylphenylazo-2-allylmalonodinitrile, 2,2′-azobis-2-methylvaleronitrile, 4,4′-azobis- Dimethyl 4-cyanovalerate, 2,2′-azobis-2,4-dimethylvaleronitrile, 1,1′-azobiscyclohexanenitrile, 2,2′-azobis-2-propylbutyronitrile, 1,1 ′ -Azobiscyclohexanenitrile, 2,2'-azobis-2-propylbutyronitrile, 1,1'-azobis-1-chlorophenylethane, 1,1'-azobis-1-cyclohexanecarbonitrile, 1,1'- Azobis-1-cycloheptanenitrile, 1,1′-azobis-1-phenylethane, 1,1′-azobiscumene, 4-nitro Ethyl azobenzyl cyanoacetate, phenylazodiphenylmethane, phenylazotriphenylmethane, 4-nitrophenylazotriphenylmethane, 1,1'-azobis-1,2-diphenylethane, poly (bisphenol A-4,4'- Azo radical polymerization initiators such as azobis-4-cyanopentanoate) and poly (tetraethylene glycol-2,2′-azobisisobutyrate), acetyl peroxide, cumyl peroxide, tert-butyl peroxide, Propionyl peroxide, benzoyl peroxide, 2-chlorobenzoyl peroxide, 3-chlorobenzoyl peroxide, 4-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, 4-bromomethylbenzoyl peroxide, lauroyl peroxide, Potassium persulfate, diisopropyl peroxycarbonate, tet Larin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, tert-butyl perphenylacetate, tert-butyl hydroperoxide, tert-butyl performate, tert-butyl peracetate, tert-butyl benzoate Tert-butyl perphenyl acetate, tert-butyl permethoxyacetate, tert-butyl per-N- (3-toluyl) carbamate and the like. Examples of the polymerization initiator include peroxide radical polymerization initiators such as benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, and methyl ethyl ketone peroxide. These may be used alone or in combination of two or more.

Moreover, a mercapto compound can be added as a chain transfer agent. For example, chain transfer agents having hydroxyl groups such as mercaptoethanol, mercaptopropanol, mercaptobutanol, mercaptopropanediol, mercaptobutanediol, hydroxybenzenethiol and derivatives thereof; 1-butanethiol, butyl-3-mercaptopropionate, methyl- 3-mercaptopropionate, 2,2- (ethylenedioxy) diethanethiol, ethanethiol, 4-methylbenzenethiol, dodecyl mercaptan, propanethiol, butanethiol, pentanethiol, 1-octanethiol, cyclopentanethiol, Examples include cyclohexanethiol, thioglycerol, and 4,4-thiobisbenzenethiol. These may be used alone or in combination of two or more.

In the low dielectric resin composition of the present invention, the weight ratio between the (A) epoxy resin and the (B) (meth) acrylic acid ester copolymer is not particularly limited, but is 99 to 50%: 1 to 50%. It is preferably 90 to 70%: more preferably 10 to 30%. (A) When the weight ratio of the epoxy resin is less than 50%, the sea portion containing (A) the epoxy resin and the island portion containing (B) (meth) acrylic acid ester copolymer are reversed, resulting in a predetermined hardness such as hardness. The cured product characteristics may be deteriorated, and if it exceeds 99%, the sea-island structure may not be formed. (B) When the weight ratio of the (meth) acrylic acid ester copolymer is less than 1%, a sea-island structure may not be formed. When it exceeds 50%, (A) a sea part containing an epoxy resin and (B ) As a result of the reversal of the island portion containing the (meth) acrylic acid ester copolymer, a predetermined cured product characteristic such as hardness may be deteriorated.

When the low dielectric resin composition of the present invention contains a curing agent (C) described later, the content of (B) (meth) acrylic acid ester copolymer is not particularly limited, but (A) an epoxy resin and (C) It is preferable that it is 10-75 weight part with respect to a total of 100 weight part with a hardening | curing agent, and it is more preferable that it is 20-40 weight part. When the content is less than 10 parts by weight, flexibility may be deteriorated, and when it exceeds 75 parts by weight, predetermined cured product characteristics such as hardness may be deteriorated.

The low dielectric resin composition of the present invention may optionally contain other components in addition to (A) the epoxy resin and (B) (meth) acrylic acid ester copolymer. Examples of other components include, but are not limited to, (C) curing agent, (D) inorganic filler, (E) curing accelerator, (F) organic solvent, antioxidant, light stabilizer, flame retardant, Examples include an antifoaming agent, a coupling agent, an ion trapping agent, a pigment, and a leveling agent.

<(C) Curing agent>
(C) As the curing agent, those generally used as the curing agent for (A) epoxy resin can be used. For example, a diamine curing agent, a polyamide curing agent, an acid anhydride curing agent. And compounds having two or more phenolic hydroxyl groups in one molecule, various phenol resins, polyphenylene ether compounds (PPE), and the like. These may be used alone or in combination of two or more.

When the low dielectric resin composition of the present invention contains (C) a curing agent, the content is not particularly limited, but is preferably 10 to 100 parts by weight with respect to 100 parts by weight of (A) epoxy resin. More preferably, it is 20 to 80 parts by weight. If the content is less than 10 parts by weight, the glass transition temperature may decrease, resulting in a decrease in heat resistance. If the content exceeds 100 parts by weight, the glass transition temperature may decrease, resulting in a decrease in heat resistance. is there.

<(D) Inorganic filler>
By blending the inorganic filler (D) in the low dielectric resin composition of the present invention, the coefficient of thermal expansion (CTE) of the low dielectric cured product can be reduced. (D) Although it does not specifically limit as an inorganic filler, For example, metal oxides, such as a silica and an alumina, a metal hydrate etc. are mentioned. These may be used alone or in combination of two or more.

<(E) Curing accelerator>
(E) Although it does not specifically limit as a hardening accelerator, For example, imidazoles and its derivative (s), an organic phosphate type compound, secondary amines, tertiary amines, a quaternary ammonium salt etc. are mentioned. These may be used alone or in combination of two or more.

When the low dielectric resin composition of the present invention contains (E) a curing accelerator, its content is not particularly limited, but it is 1 to 10 parts by weight with respect to 100 parts by weight of (A) epoxy resin. The amount is preferably 3 to 8 parts by weight. If the content is less than 1 part by weight, curing failure may occur, and if it exceeds 10 parts by weight, the water resistance may decrease.

<(F) Organic solvent>
A varnish can be adjusted by mix | blending the organic solvent (F) with the low dielectric resin composition of this invention. (F) The organic solvent is not particularly limited, and examples thereof include ketone solvents such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone and cyclohexane, ester solvents such as ethyl acetate and butyl acetate, and aromatics such as toluene and xylene. And nitrogen-containing solvents such as dimethylformamide and dimethylformamide. These may be used alone or in combination of two or more.

When the low dielectric resin composition of the present invention contains (F) an organic solvent, the content is not particularly limited, but is preferably 20 to 80% by weight in the low dielectric resin composition, and 30 to 60 More preferably, it is% by weight. When the content is less than 20% by weight, the viscosity may increase and handling may be difficult. When the content exceeds 80% by weight, the viscosity may decrease and handling may be difficult.

Although it does not specifically limit as a use of the low dielectric resin composition of this invention, For example, a coverlay film, a bonding sheet, a prepreg, etc. are mentioned.

The coverlay film and the bonding sheet can be produced by applying the low dielectric resin composition of the present invention to at least one surface of a film such as an electrically insulating film or a release film to form an adhesive layer. Specific examples include a film-based coverlay film having a three-layer structure of an electrical insulating film / adhesive layer / release film, a three-layer structure of release film / adhesive layer / release film, or a mold release. Examples thereof include a dry film type coverlay film and a bonding sheet having a two-layer structure of film / adhesive layer. Also, by laminating like electrical insulating film / adhesive layer / metal foil, laminating like single side flexible printed wiring board or metal foil / adhesive layer / electrical insulating film / adhesive layer / metal foil By doing so, a double-sided flexible printed wiring board etc. can also be manufactured.

The material of the electrical insulating film is not particularly limited. For example, polyimide film, polyethylene terephthalate (PET) film, polyester film, polyparabanic acid film, polyetheretherketone film, polyphenylene sulfide film, aramid film, polycarbonate film, poly An arylate film etc. are mentioned. Although the thickness of an electrically insulating film is not specifically limited, It is preferable that it is 3-200 micrometers. Further, the electrical insulating film may be a laminate of a plurality of films, and may be subjected to surface treatment such as hydrolysis, corona discharge, low temperature plasma, physical roughening, and easy adhesion coating treatment as necessary. .

The release film is not particularly limited. For example, a polyolefin film, a polyester film, a TPX film, a film in which a release agent layer is provided on these films, and a paper obtained by laminating these films on a paper base material. Can be used.

Although it does not specifically limit as metal foil, For example, electrolytic copper foil, rolled copper foil, aluminum foil, tungsten foil, iron foil etc. are mentioned. Among these, electrolytic copper foil, rolled copper foil, and the like are preferable from the viewpoints of workability, flexibility, electrical conductivity, and the like.

In manufacturing a film-based coverlay film, first, a varnish of a low dielectric resin composition is applied to an electrically insulating film using a comma coater, a die coater, or the like. Next, this is passed through an in-line drier and heated to remove the solvent contained in the varnish to form an adhesive layer. Next, the surface of the adhesive layer of the electrically insulating film with the adhesive layer On the other hand, a film-based coverlay film can be obtained by pressure-bonding the release film with a hot roll or the like. At this time, it is also possible to obtain a flexible printed wiring board by using a metal foil instead of the release film and curing the adhesive layer by a heating process after pressure bonding the metal foil.

In producing a dry film type coverlay film or a bonding sheet, first, a varnish of a low dielectric resin composition is applied to a release film using a comma coater, a die coater or the like. Next, this is passed through an in-line dryer, and dried by heating to remove the solvent contained in the varnish to form an adhesive layer, and then if necessary, the adhesive layer of the release film with the adhesive layer. A dry film type coverlay film or a bonding sheet can be obtained by further pressing the release film on the surface with a hot roll or the like.

The prepreg is obtained by impregnating a varnish of a low dielectric resin composition into a base material such as a woven fabric or a non-woven fabric, and heating and drying the varnish through an in-line dryer to remove the solvent contained in the varnish. Is. Although it does not specifically limit as this base material, From a heat resistant and workable viewpoint, it is preferable to use a glass woven fabric, a glass nonwoven fabric, etc.

After laminating a metal foil on one side or both sides of the prepreg thus obtained, a laminate for a printed wiring board can be produced by heating and pressing it. In addition, the prepreg laminated | stacked with metal foil can use what laminated | stacked not only 1 sheet but multiple sheets.

<< Low dielectric hardened material >>
The low dielectric cured product of the present invention is a low dielectric cured product obtained by curing the low dielectric resin composition of the present invention,
(A) It has a sea-island structure consisting of a sea part containing an epoxy resin and an island part containing (B) a (meth) acrylic acid ester copolymer,
(B) The major axis of the island part containing the (meth) acrylic acid ester copolymer is 0.1 to 10 μm.

The low dielectric cured product of the present invention is, for example, a roll coating method, a bar coating method, a dip coating method, a blade coating method, a curtain coating method, a spray coating method, a doctor coating method, etc. It can manufacture by heat-processing for 10 to 200 minutes at 60-200 degreeC after apply | coating.

The low dielectric cured product of the present invention is also laminated by heating and drying the low dielectric resin composition of the present invention until it is in a semi-cured state (B stage), and this is laminated at 140 to 200 ° C. for 10 to 200 minutes. It can also be manufactured by heat-curing and transferring to the C stage.

In producing the low dielectric cured product of the present invention, after impregnating the fiber base material with the low dielectric resin composition of the present invention, the semi-cured state (B stage) is applied to the C stage by the method described above. May be migrated. Although it does not specifically limit as a fiber base material, For example, a glass cloth, an aramid cloth, a polyester cloth etc. can be used. These may be used alone or in combination of two or more.

The low dielectric hardened | cured material of this invention has the sea island structure which consists of the sea part containing (A) epoxy resin, and the island part containing (B) (meth) acrylic acid ester copolymer. (B) The long diameter of the island part containing a (meth) acrylic acid ester copolymer is 0.1-10 micrometers. (B) If the major axis of the island part containing the (meth) acrylic acid ester copolymer is less than 0.1 μm, the stress relaxation characteristics may be reduced, and if it exceeds 10 μm, the predetermined cured product characteristics such as hardness will be reduced. Sometimes.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to a following example. Hereinafter, “part” or “%” means “part by weight” or “% by weight”, respectively, unless otherwise specified.

(Comparative Synthesis Examples 1-4, Synthesis Examples 1-6) (B) (Meth) acrylic acid ester copolymer production 1300 parts by weight of water was placed in a four-necked flask equipped with a stirrer, and polyvinyl as a dispersion stabilizer. While dissolving 3 parts by weight of alcohol and stirring, 430 parts by weight of a mixture in which the monomer components were mixed at a weight ratio shown in Table 1 and 4 parts by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator were collectively used. The suspension was prepared. The suspension was heated to 68 ° C. with continued stirring and reacted for 4 hours. Then, it cooled to room temperature (about 25 degreeC). Next, the reaction product was separated into solid and liquid, sufficiently washed with water, and then dried using a dryer to obtain a (B) (meth) acrylic acid ester copolymer.

Carboxy-terminated butyl nitrile rubber (CTBN) (manufactured by Nippon Zeon Co., Ltd., 1072J), and (B) (meth) acrylic acid ester copolymer obtained in Comparative Synthesis Examples 1-4 and Synthesis Examples 1-6, The weight average molecular weight, the ratio of the weight average molecular weight to the number average molecular weight (dispersion degree), solvent solubility, dielectric constant and dispersibility were evaluated by the following methods. The results are shown in Table 1.

(Weight average molecular weight and number average molecular weight)
It calculated | required in standard polystyrene conversion by the gel permeation chromatography (GPC) method.

(Solvent solubility)
(B) 5 parts by weight of (meth) acrylic acid ester copolymer or CTBN is mixed with 95 parts by weight of methyl ethyl ketone (MEK) and kept at 60 ° C., and (B) (meth) acrylic acid ester copolymer or CTBN is completely The time required for dissolution was measured and evaluated according to the following criteria.
○: Completely dissolved in less than 24 hours.
(Triangle | delta): It melt | dissolved completely in 24 hours or more and less than 72 hours.
X: Insoluble at 72 hours (not completely dissolved).

(Dielectric constant)
(B) A sample was prepared by molding a (meth) acrylic acid ester copolymer or CTBN into a size of 50 mm × 50 mm × 1 mm. This sample was measured by a parallel plate capacitor method, and the subsequent dielectric constant and dielectric loss tangent were calculated by the following equations.
εr = (ta × Cp) / (A × ε0)
= (Ta × Cp) / (π × (d / 2) 2 × ε0)
Dt = D
εr: dielectric constant of sample ta: average thickness of sample [m]
Cp: equivalent parallel capacitance [F]
A: Area of main electrode [m ² ]
ε0: Dielectric constant of vacuum (= 8.854 × 10 ⁻¹² )
d: Diameter of main electrode [m]
Dt: Dielectric loss tangent of sample D: Dielectric loss tangent

(Dispersibility)
(A) Epoxy resin and (B) (meth) acrylic acid ester copolymer were mixed with methyl ethyl ketone (MEK), and the separated state after the lapse of 2 hours was visually observed and evaluated according to the following criteria.
○: Not separated after 2 hours.
×: Separated after 2 hours.

(Comparative Examples 1-5, Examples 1-14) Production of Low Dielectric Resin Composition (A) 100 parts by weight of cresol novolac type epoxy resin (DIC Corporation, N-680) as epoxy resin, (C) curing 50 parts by weight of phenol novolak (manufactured by DIC Corporation, TD-2093) as an agent, (E) 1 part by weight of 2-methylimidazole (manufactured by Shikoku Kasei Co., Ltd., 2MZ), (B) (meth) acrylic acid CTBN as an ester copolymer or (B) (meth) acrylic acid ester copolymer prepared in Comparative Synthesis Examples 1 to 4 and Synthesis Examples 1 to 6 are mixed at a weight ratio shown in Table 2, and a low dielectric resin composition I got a thing.

Using the low dielectric resin compositions obtained in Comparative Examples 1 to 5 and Examples 1 to 14, the phase separation state (sea-island structure) was evaluated by the following method. The results are shown in Table 2.
The low dielectric resin composition of Comparative Example 4 was separated because the dispersibility of the (B) (meth) acrylic acid ester copolymer prepared in Comparative Synthesis Example 3 was poor, and the phase separation state (Kaijima Structure) could not be evaluated. Moreover, since the (B) (meth) acrylic acid ester copolymer produced in Comparative Synthesis Example 4 was hardly soluble in the solvent, the low dielectric resin composition of Comparative Example 5 had a phase separation state (sea-island structure). Could not be evaluated.

(Phase separation state (sea island structure))
The resin composition was molded into a film having a film thickness of 50 μm or less and cured by heating and curing at 180 ° C. for 120 minutes to obtain a cured product. The appearance of the surface of the obtained cured product was observed with an electron microscope, the major axis of the island was measured, and evaluated according to the following criteria.
○: The major axis of the island is 0.1 to 10 μm.
X: The long diameter of an island part is less than 0.1 micrometer or exceeds 10 micrometers.

Claims (11)

Low dielectric resin containing (A) epoxy resin and (B) glycidyl (meth) acrylate, alkyl (meth) acrylate and (meth) acrylic acid ester copolymer obtained by copolymerizing aromatic vinyl compound A composition comprising:
(B) The (meth) acrylic acid ester copolymer has a weight average molecular weight of 5,000 to 1,000,000 and a dielectric constant of 3.0 or less. The low dielectric resin composition according to claim 1, wherein the alkyl group of the alkyl (meth) acrylate has 2 to 18 carbon atoms. (B) The weight ratio of the monomer component in the (meth) acrylic acid ester copolymer is glycidyl (meth) acrylate: alkyl (meth) acrylate: aromatic vinyl compound = 1-15%: 25-98%: 1-60. The low dielectric resin composition according to claim 1 or 2, wherein the composition is%. The low dielectric resin composition according to any one of claims 1 to 3, wherein the (B) (meth) acrylic acid ester copolymer has a ratio of the weight average molecular weight to the number average molecular weight of 4 or less. (A) The epoxy resin is a group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin and dicyclopentadiene type epoxy resin. The low dielectric resin composition according to claim 1, wherein the low dielectric resin composition is at least one selected from the group. (C) a curing agent is further included, and (A) 10 to 75 parts by weight of (meth) acrylic acid ester copolymer is included with respect to 100 parts by weight of the total of (A) epoxy resin and (C) curing agent, The low dielectric resin composition of any one of Claims 1-5. A low dielectric cured product obtained by curing the low dielectric resin composition according to any one of claims 1 to 6,
(A) It has a sea-island structure consisting of a sea part containing an epoxy resin and an island part containing (B) a (meth) acrylic acid ester copolymer,
(B) The low dielectric hardened | cured material characterized by the long diameter of the island part containing a (meth) acrylic acid ester copolymer being 0.1-10 micrometers. A coverlay film, wherein the low dielectric resin composition according to any one of claims 1 to 6 is applied to at least one surface of the film. A bonding sheet, wherein the low dielectric resin composition according to claim 1 is applied to at least one surface of a film. A prepreg, wherein the low dielectric resin composition according to any one of claims 1 to 6 is impregnated in a woven fabric or a non-woven fabric. A laminate for a printed wiring board, wherein a metal foil is laminated on one side or both sides of the prepreg according to claim 10.