JP2021195411A - Curable composition - Google Patents

Abstract

To provide a curable composition capable of imparting a sufficient breakdown strength to a cured product after curing.SOLUTION: A curable composition includes: a block copolymer having a polyolefin block structure and a polystyrene block structure in a molecule and a hydroxy group at one end of a molecular chain; and an urethanization reaction product of a polyisocyanate compound having a plurality of isocyanate groups in a molecule, a polyol compound having a plurality of hydroxy groups in a molecule, and a hydroxy (meth)acrylate having one (meth)acryloyl group, a hydroxy group and a C1 to C4 saturated alkyl in a molecule.SELECTED DRAWING: None

Description

The present invention relates to a curable composition that is cured by, for example, light irradiation.

Conventionally, curable compositions that are cured by light irradiation include, for example, urethane acrylate (A) synthesized from hydrogenated polybutadiene diol or hydrogenated polyisoprene diol and having a number average molecular weight of 1,000 to 20,000. A curable composition comprising a monofunctional (meth) acrylate monomer (B) and an initiator (C) having an absorption band at a wavelength of 380 nm or more, wherein the content of the component (C) is the component (A). A curable composition having an amount of 10 to 15 parts by weight based on 100 parts by weight of the components (B) is known (for example, Patent Document 1).

The curable composition described in Patent Document 1 is applied onto an electronic circuit and then cured by irradiation with light, and is used in electronic circuit coating applications.
The curable composition described in Patent Document 1 can be cured even with light from an LED light source, and can have good moisture resistance, electrical insulation, and the like.

Japanese Unexamined Patent Publication No. 2018-024761

However, the cured product obtained by curing the curable composition described in Patent Document 1 may not necessarily have sufficient dielectric breakdown strength. Therefore, there is a demand for a curable composition in which the cured product after curing has sufficient dielectric breakdown strength.

In view of the above problems and the like, it is an object of the present invention to provide a curable composition capable of the cured product after curing having sufficient dielectric breakdown strength.

In order to solve the above problems, the curable composition according to the present invention is
A block copolymer having a polyolefin block structure and a polystyrene block structure in the molecule and having a hydroxy group at one end of the molecular chain,
Polyisocyanate compounds having multiple isocyanate groups in the molecule,
A polyol compound having multiple hydroxy groups in the molecule, and
A hydroxy (meth) acrylate having one (meth) acryloyl groups and one hydroxyl group and C ₁ -C ₄ saturated alkyl in the molecule,
It is characterized by containing the urethanization reaction product of.
Since the above curable composition contains a urethanization reaction product having a (meth) acryloyl group in the molecule, these reaction products can be polymerized and polymerized, so that the curable composition is cured by light irradiation or the like. obtain.
Further, the cured product after curing can have sufficient dielectric breakdown strength.

The curable composition according to the present invention contains the urethanization reaction product having both the (meth) acryloyl group derived from the hydroxy (meth) acrylate and the isocyanate group derived from the polyisocyanate compound in the molecule. But it may be.
Urethane reaction products that also have an isocyanate group in the molecule can be polymerized by binding to each other due to moisture (moisture), and thus are sufficiently cured by moisture. Therefore, the above-mentioned curable composition can be sufficiently cured even by moisture.

In the curable composition according to the present invention, the urethanization reaction product may not have reactivity with the isocyanate group derived from the polyisocyanate compound.

The polyolefin block structure of the block copolymer may include a random sequence structure of ethylene units and propylene units.

The polyisocyanate compound may have 2 or more and 4 or less of the isocyanate groups in the molecule.

The polyol compound may have 2 or more and 4 or less of the hydroxy groups in the molecule.

The curable composition according to the present invention is
A saturated cycloalkyl (meth) acrylate monomer having a saturated cyclic hydrocarbon structure and a (meth) acryloyl group in the molecule, and
A saturated chain alkyl (meth) acrylate monomer having a saturated chain hydrocarbon structure and a (meth) acryloyl group in the molecule, and
May be further included.
Since the curable composition contains a saturated chain alkyl (meth) acrylate monomer, the urethanization reaction product containing the structure of the block copolymer can be satisfactorily dissolved in the curable composition. can.
Further, since the above-mentioned curable composition contains a saturated cycloalkyl (meth) acrylate monomer, the cured product after curing can have sufficient moisture resistance.

According to the curable composition according to the present invention, the cured product after curing can have sufficient dielectric breakdown strength.

FIG. 1 is a schematic diagram schematically showing an example of a urethanization reaction product. FIG. 2 is a schematic diagram schematically showing another example of the urethanization reaction product.

Hereinafter, an embodiment of the curable composition according to the present invention will be described.

The curable composition of the present embodiment comprises a block copolymer having a polyolefin block structure and a polystyrene block structure in the molecule and having a hydroxy group at one end of the molecular chain.
Polyisocyanate compounds having multiple isocyanate groups in the molecule,
A polyol compound having multiple hydroxy groups in the molecule, and
A hydroxy (meth) acrylate having one (meth) acryloyl groups and one hydroxyl group and C ₁ -C ₄ saturated alkyl in the molecule,
Contains the urethanization reaction product of.

The curable composition of the present embodiment contains the above-mentioned urethanization reaction product, and such a urethanization reaction product has a block copolymer structure having a polyolefin block structure and a polystyrene block structure, and the above-mentioned polyisocyanate compound. A urethanization reaction product having a structure derived from the above, a structure derived from the polyol compound, and at least one (meth) acryloyl group in the molecule (hereinafter, may be simply referred to as “main reaction product”). include.
The above-mentioned urethanization reaction product has neither a benzene ring structure (aromatic hydrocarbon composed of 6 cyclic carbon atoms) nor a saturated cycloalkyl structure (saturated cyclic hydrocarbon structure) in the molecule. Is preferable.

Since the curable composition of the present embodiment contains a urethanization reaction product having a (meth) acryloyl group in the molecule, these products undergo a polymerization reaction with each other when irradiated with light such as ultraviolet rays. By polymerizing these products with each other, polymerization (curing reaction) proceeds and curing occurs.
The cured product can have sufficient dielectric breakdown strength.

The curable composition of the present embodiment may contain a urethanization reaction product (main reaction product) further having at least one isocyanate group in the molecule, if necessary.
In this case, since the main reaction product has −NCO (isocyanate group) in the molecule, the −NCOs of these products react with each other even with the humidity in the air, and these products bind to each other. Since polymerization (curing reaction) also proceeds by this bond, curing can be sufficiently promoted.

The curable composition of the present embodiment contains, for example, monool (hereinafter, also simply referred to as <A component>), which is a block copolymer having a polyolefin block structure and a polystyrene block structure in the molecule, and a plurality of isocyanate groups. A polyisocyanate compound (hereinafter, also simply referred to as <B component>) contained in the molecule, a polyol compound having a plurality of hydroxy groups in the molecule (hereinafter, also simply referred to as <C component>), and one (meth) acryloyl. It contains a hydroxy (meth) acrylate having a group, one hydroxy group and a C _{1 to} C ₄ saturated alkyl in the molecule (hereinafter, also simply referred to as <D component>) and a urethanization reaction product.
In other words, the curable composition of the present embodiment contains, for example, a urethanization reaction product obtained by subjecting at least <A component>, <B component>, <C component> and <D component> to a urethanization reaction.
Preferably, the curable composition of the present embodiment has a saturated cycloalkyl (meth) acrylate monomer having a saturated cyclic hydrocarbon structure and a (meth) acryloyl group in the molecule, a saturated chain hydrocarbon structure and (meth). It further comprises a saturated chain alkyl (meth) acrylate monomer having an acryloyl group in the molecule.

The above curable composition is obtained, for example, by subjecting at least <A component>, <B component>, <C component>, and <D component> to a urethanization reaction.
Therefore, the curable composition of the present embodiment contains the main reaction product described above, and also contains products other than the main reaction product produced by the urethanization reaction.
The curable composition of the present embodiment also contains a trace amount of the urethanization reaction catalyst used for the urethanization reaction.

<Component A>
The component A is a block copolymer having a polyolefin block structure and a polystyrene block structure in the molecule and having a hydroxy group at one end of the molecular chain. In other words, component A is a block copolymer monool having a polyolefin block structure and a polystyrene block structure.
Specifically, the block copolymer described above has a polystyrene block structure at both ends of the molecular chain, and has a polyolefin block structure between these polystyrene block structures. In addition, the above block copolymer has a hydroxy group at one end of the molecular chain.

The polyolefin block structure does not contain polar groups such as ether groups and ester groups, and is composed only of hydrocarbon groups. Such a hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. Such hydrocarbon groups may contain both saturated and unsaturated hydrocarbon groups. Most of the polyolefin block structures are preferably composed of saturated hydrocarbons.
The polyolefin block structure may contain unsaturated hydrocarbon groups in terms of further curing the curable composition of the present embodiment, while the cured product of the curable composition of the present embodiment has better heat resistance. It is preferable that the proportion of unsaturated hydrocarbon groups in the polyolefin block structure is small in that it can have properties and weather resistance. For example, the ratio of unsaturated hydrocarbon groups in the polyolefin block structure to the total mass of the curable composition may be 10% by mass or less, or 5% by mass or less.

The polyolefin block structure has a structural unit such as ethylene, propylene, 1,3-butadiene (and its hydrogenated body), and isoprene (and its hydrogenated body) as a structural unit. The polyolefin block structure is usually composed of saturated bonds, but may have unsaturated bonds in part. As the structural unit, ethylene, propylene, butylene (-CH ₂ CH (CH ₂ CH ₃ )-) is preferable. In other words, the polyolefin block structure preferably contains at least one of ethylene, propylene, and butylene as a constituent unit.

In the polyolefin block structure, each structural unit may be randomly arranged. In other words, each structural unit may be one in which a plurality of different types of monomers are incorporated into the molecular chain by random polymerization.
For example, the polyolefin block structure may include a random sequence structure of ethylene constituent units and propylene constituent units.

The degree of polymerization in the polyolefin block structure is, for example, 100 or more and 1,000 or less.

Each polystyrene block structure in the component A has styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, t-butylstyrene, 2,4-dimethylstyrene, 2,4 as constituent units. -Has a structural unit such as diethylstyrene. The constituent unit includes one or more of these. As the structural unit, a structural unit of styrene or α-methylstyrene is preferable. In other words, each polystyrene block structure preferably has at least one of styrene or α-methylstyrene as a constituent unit.

The degree of polymerization of each polystyrene block structure is, for example, 50 or more and 100 or less.

Examples of the block copolymer include a styrene-butadiene-styrene block copolymer (SBS), a styrene-isoprene-styrene block copolymer (SIS), and a styrene-ethylene / butene-styrene block copolymer (SEBS). ), A styrene-ethylene / propylene-styrene block copolymer (SEPS), a styrene-ethylene / ethylene / propylene-styrene block copolymer (SEEPS), and the like having a hydroxy group at one end. The block copolymer described above is preferably a styrene-ethylene / ethylene / propylene-styrene block copolymer (SEEPS) having a hydroxy group at one end.

The proportion of the polystyrene block structure in the above block copolymer may be 10% by mass or more and 50% by mass or less, and preferably 20% by mass or more and 40% by mass or less.

The block copolymer (component A) does not contain a reactive group such as an isocyanate group or a glycidyl group in the molecule. Further, the main chain of the block copolymer does not contain either nitrogen (N) constituting a urethane bond or an amide bond, or sulfur (S) constituting a sulfonyl group or the like.
The block copolymers described above usually do not have a crosslinked structure and are not modified. The terminal portion of the molecular chain of the block copolymer may be a residue of a polymerization initiator or the like.

The preferred molecular structure of the block copolymer (component A) having a hydroxy group at one end of the molecular chain as described above is schematically represented by the following formula (1). Formula (1) represents a structure having a hydroxy group at one end of SEEPS. In the following formula (1), p is 50 or more and 100 or less, q is 100 or more and 500 or less, r is 400 or more and 1,000 or less, s is 50 or more and 100 or less, and m is 500 or more and 1, It may be 500 or less.

The block copolymer may have, for example, a number average molecular weight of 10,000 or more and 100,000 or less.

As the component A, a commercially available product can be used. For example, the product name "Septon HG252" (manufactured by Kuraray Co., Ltd.) can be used.

<B component>
The B component is a polyisocyanate compound having a plurality of isocyanate groups in the molecule. The polyisocyanate compound preferably has 2 or more and 4 or less isocyanate groups in the molecule, and more preferably 3 or more and 4 or less in the molecule.

Examples of the isocyanate compound of the component B include aromatic polyisocyanates such as toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthylene diisocyanate, and xylylene diisocyanate.
Examples of the isocyanate compound of the B component include hexamethylene diisocyanate (HDI), hydrogenated diphenylmethane diisocyanate (H-MDI), hydrogenated xylylene diisocyanate (H-XDI), isophorone diisocyanate (IPDI), and norbornan diisocyanate. Examples thereof include aliphatic polyisocyanates such as (NBDI), 1,3-bis (isocyanatemethyl) cyclohexane (H6XDI), L-lysine diisocyanate (LDI), and 1,6,11-undecantry isocyanate.
Further, the isocyanate compound of the B component may be, for example, a dimer-modified product, a trimer-modified product, an isocyanurate-type product, an adduct-modified product, a bullet-modified product, an allophanate-modified product, or the like of the above-mentioned polyisocyanate compound. .. Further, it may be a blocked isocyanate compound in which the isocyanate group of the above polyisocyanate compound is blocked.

The polyisocyanate compound of the component B is preferably at least one selected from isocyanurates, adduct-modified and biuret-modified compounds of aliphatic diisocyanates having 6 to 10 total carbon atoms. The polyisocyanate compound of component B preferably has 3 or 4 isocyanate groups in the molecule. The polyisocyanate compound of the component B preferably has neither a benzene ring structure (aromatic ring structure) nor a saturated cycloalkyl structure (saturated cyclic structure in which the ring is composed of only carbon atoms) in the molecule.

The isocyanurate form as the B component is, for example, the above-mentioned hexamethylene diisocyanate (HMDI) trimer and has three isocyanate groups in the molecule.

The modified adduct as the B component is, for example, a reaction product of trimethylolpropane and an aliphatic diisocyanate having a total carbon number of 6 to 10 (such as HMDI described above). Such an adduct modified product has three isocyanate groups in the molecule.

The component B does not contain a benzene ring and has good weather resistance after curing, and also has good solubility in the diluent when a diluent is allowed to coexist in the urethanization reaction. , Adduct-modified product obtained by reacting hexamethylene diisocyanate (HMDI) with trimethylolpropane, or isocyanurate (trimer) of hexamethylene diisocyanate (HMDI) is preferable.

<C component>
The C component is a polyol compound having a plurality of hydroxy groups in the molecule. As the polyol compound, a compound having 3 or more and 12 or less carbon atoms and 2 or more and 4 or less hydroxy groups is preferable.
The polyol compound may contain an ether bond, an ester bond, or the like in the molecule. Further, the polyol compound may contain N (nitrogen), P (phosphorus), or S (sulfur) in the molecule.

Examples of the polyol compound (diol compound) having two hydroxy groups include ethylene glycol (2 carbon atoms, -OH group number 2), propylene glycol (3 carbon atoms, -OH group number 2), and neopentyl glycol (5 carbon number carbon atoms). , -OH group number 2) and the like.
Examples of the polyol compound (triol compound) having three hydroxy groups include glycerin (3 carbon atoms, 3 −OH groups), trimethylolpropane (6 carbon atoms, 3 −OH groups) and the like.
Examples of the polyol compound having four hydroxy groups include ditrimethylolpropane (12 carbon atoms, -OH group number 4), diglycerin (6 carbon number, -OH group number 4), and erythritol (4 carbon number, -OH group number 4). ), Pentaerythritol (5 carbon atoms, 4 −OH groups), D-treitol (4 carbon atoms, 4 −OH groups) and the like.
Examples of the polyol compound having five hydroxy groups include L-arabitol (5 carbon atoms, 5 −OH groups), ribitol (5 carbon atoms, 5 −OH groups), and xylitol (5 carbon atoms, 5 −OH groups). , Ramnitol (6 carbon atoms, 5 −OH groups) and the like.
Examples of the polyol compound having 6 hydroxy groups include dipentaerythritol (10 carbon atoms, 6 −OH groups), sorbitol (6 carbon atoms, 6 −OH groups), and mannitol (6 carbon atoms, 6 −OH groups). , Galactitol (6 carbon atoms, 6 −OH groups) and the like.
Examples of the polyol compound include sugars such as arabinose, ribose, xylose, glucose, mannose, galactose, frucose, sorbose, rhamnose, fucose, ribodesource, trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, and melibiose. Be done.

<D component>
Component D, at one (meth) acryloyl groups and one hydroxyl group and, C ₁ -C ₄ saturated alkyl hydroxy (meth) acrylate having a (having 1 to 4 saturated hydrocarbon carbon), the in the molecule be.
In other words, D component has a (meth) C ₁ -C ₄ saturated alkyl esters of acrylic acid, one hydroxy group bonded to any carbon of the alkyl moiety. D component is preferably a hydroxy saturated _C 2 -C ₃ alkyl (meth) acrylate.

Examples of the D component include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth). Examples include acrylate. The component D is preferably 2-hydroxyethyl (meth) acrylate in that the polymerizability by light irradiation is better.

When producing the urethanization reaction product of the present embodiment, the ratio of the number of moles of the component B to the number of moles of the component A in the urethanization reaction is preferably 0.5 or more and 15.0 or less, preferably 3 or more. It is more preferably 7 or less.

The ratio of the number of moles of the C component to the number of moles of the A component in the urethanization reaction is preferably 0.1 or more and 14.0 or less, and more preferably 1 or more and 6 or less.

The ratio of the number of moles of the D component to the number of moles of the A component in the urethanization reaction is preferably 0.5 or more and 16.0 or less, and more preferably 2 or more and 8 or less.

The ratio of the number of moles of the isocyanate group of the component B to the number of moles of the hydroxy group of the component A in the urethanization reaction is preferably 1 or more and 60 or less, and more preferably 6 or more and 30 or less.

The ratio of the number of moles of the isocyanate group of the B component to the number of moles of the hydroxy group of the C component in the urethanization reaction is preferably 1 or more and 3 or less, and more preferably 1.5 or more and 2.5 or less. ..

The ratio of the number of moles of the isocyanate group of the component B to the number of moles of the hydroxy group of the component D in the urethanization reaction is preferably 1 or more and 60 or less, and more preferably 6 or more and 30 or less.

When the urethanization reaction is carried out so that the urethanization reaction product (main reaction product) does not have the reactivity due to the isocyanate group derived from the polyisocyanate compound, the A component and the C component are used in the urethanization reaction. The ratio of the number of moles of the isocyanate group of the component B to the total number of moles of the hydroxy group of the component D (ratio of the total number of moles) is preferably 0.5 or more and 1.0 or less, and 0.8 or more and 1. It is more preferably 0 or less.

On the other hand, when the urethanization reaction is carried out so that the urethanization reaction product (main reaction product) has reactivity with the isocyanate group derived from the polyisocyanate compound, the ratio of the total number of moles is the above. It is preferably 1.0 or more and 1.5 or less, and more preferably 1.1 or more and 1.3 or less.
By carrying out the urethanization reaction in this manner, the curable composition is a reaction product having both a (meth) acryloyl group derived from hydroxy (meth) acrylate and an isocyanate group derived from a polyisocyanate compound in the molecule. Will be included.
Since the above reaction product also has an isocyanate group in the molecule, the reaction products can be bonded to each other and polymerized by moisture (moisture), so that the curable composition can be sufficiently cured by moisture. Therefore, the above-mentioned curable composition can be cured not only by light irradiation or the like, but also by moisture.

<Urethane reaction catalyst>
As the urethanization reaction catalyst, a metal-based catalyst such as an organic tin catalyst such as dibutyltin dilaurate or stanas octoate, or an acetylacetonate complex catalyst can be used. Further, as the urethanization reaction catalyst, a tertiary amine catalyst can be used.

The curable composition (curing composition) of the present embodiment contains A component, B component, C component, D component, and a urethanization reaction product produced by a urethanization reaction in the presence of a urethanization reaction catalyst. include.

As the above-mentioned urethanization reaction product, a reaction product represented as shown in FIG. 1 is exemplified. FIG. 1 shows an example of a reaction product obtained by using a trifunctional cisyanate compound as the B component and a tetrafunctional polyol compound as the C component. In FIG. 1, m is usually 1 or more and 30 or less.
By relatively reducing the amount of the D component in the urethanization reaction, more reaction products having an isocyanate group can be produced.

Further, as the above-mentioned urethanization reaction product, a reaction product represented as shown in FIG. 2 is exemplified. FIG. 2 shows an example of a reaction product obtained by using a trifunctional cisyanate compound as the B component and a bifunctional polyol compound as the C component. In FIG. 2, n is usually 1 or more and 100 or less.

The curable composition may contain, for example, a reaction product having only an isocyanate group as a reactive group, a reaction product having only a (meth) acryloyl group as a reactive group, and the like.
From another viewpoint, in the above curable composition, for example, any two components of the A component, the C component, and the D component undergo a urethanization reaction with the B component, and the remaining one component undergoes a urethanization reaction with the B component. It may contain reaction products that did not.

The curable composition of the present embodiment further contains a photopolymerizable monomer that does not undergo a urethanization reaction. Such a photopolymerizable monomer may be blended as a diluent before the urethanization reaction in order to reduce the viscosity in the urethanization reaction system, or may be blended after the urethanization reaction.

Specifically, the curable composition of the present embodiment has a saturated cycloalkyl (meth) acrylate monomer having a saturated cyclic hydrocarbon structure and a (meth) acryloyl group in the molecule, or a saturated chain hydrocarbon structure. At least one of the saturated chain alkyl (meth) acrylate monomers having a (meth) acryloyl group in the molecule may be contained as a photopolymerizable monomer that does not undergo a urethanization reaction. These (meth) acrylate monomers are compounds that give rise to polymerization reaction products upon irradiation with light.

The saturated cycloalkyl (meth) acrylate monomer is preferably a saturated alicyclic monomer having 8 or more and 15 or less carbon atoms in the molecule. The saturated cycloalkyl (meth) acrylate monomer shall _{contain neither a benzene ring nor a polar group such as an ether bond (-CH 2-} O-CH _2- ), -OH group, and -COOH group in the molecule. Is preferable. The saturated cycloalkyl (meth) acrylate monomer is preferably a monofunctional monomer having one (meth) acryloyl group in the molecule. In the saturated cycloalkyl (meth) acrylate monomer, the saturated cycloalkyl structure may be a saturated hydrocarbon structure containing no heteroatom and composed of 4 to 8 carbon atoms. The saturated cycloalkyl (meth) acrylate monomer may be monocyclic, bicyclic or polycyclic. Bicyclic or polycyclic saturated cycloalkyl structures may share two or more carbon atoms. In the bicyclic or polycyclic saturated cycloalkyl (meth) acrylate monomer, at least one ring structure may be a saturated alkyl structure, and for example, all ring structures may be a saturated alkyl structure. In the saturated cycloalkyl (meth) acrylate monomer, a methyl group or an ethyl group may be further bonded to the carbon having a saturated cyclic hydrocarbon structure.

Specifically, the saturated cycloalkyl (meth) acrylate monomer includes isobornyl (meth) acrylate (containing a norbornane structure), dicyclopentadieneoxyethyl (meth) acrylate (containing a norbornane structure), and dicyclopentanyl (meth). ) Acrylate (containing a norbornane structure), dicyclopentenyloxyethyl (meth) acrylate (containing a norbornane structure), adamantyl (meth) acrylate and the like, and among them, those containing a norbornane structure are preferable.
When the above-mentioned curable composition contains a saturated cycloalkyl (meth) acrylate monomer, the moisture resistance of the cured product after curing can be improved.

The saturated chain alkyl (meth) acrylate monomer is preferably a (meth) acrylate monomer having a saturated chain hydrocarbon having 8 or more and 15 or less carbon atoms in the molecule. The saturated chain alkyl (meth) acrylate monomer _{contains neither a benzene ring nor a polar group such as an ether bond (-CH 2-} O-CH _2- ), -OH group, and -COOH group in the molecule. Is preferable. The saturated chain alkyl (meth) acrylate monomer is preferably a monofunctional monomer having one (meth) acrylate group in the molecule. In the saturated chain alkyl (meth) acrylate monomer, the saturated chain hydrocarbon structure may be a saturated chain hydrocarbon structure containing 7 to 11 carbon atoms without containing atoms other than C and H. ..
When the above curable composition contains a saturated chain alkyl (meth) acrylate monomer, the flexibility of the cured product obtained by the curable composition can be further improved.

In the saturated chain alkyl (meth) acrylate monomer, the saturated chain hydrocarbon structure may be linear or branched. In other words, the saturated chain hydrocarbon structure may be a saturated linear hydrocarbon structure or a saturated branched chain hydrocarbon structure. In other words, the saturated chain alkyl (meth) acrylate monomer may be a saturated linear alkyl (meth) acrylate monomer or a saturated branched chain alkyl (meth) acrylate monomer.
As the saturated chain alkyl (meth) acrylate monomer, a saturated branched alkyl (meth) acrylate monomer is preferable in that the above-mentioned urethanization reaction product can be more sufficiently dissolved in the curable composition. As a result, a more uniform cured product film can be obtained without being affected by the substrate on which the cured product is supported, the thickness of the cured product, or the curing reaction conditions.

In the curable composition of the present embodiment, the ratio of the saturated cycloalkyl (meth) acrylate monomer to 100 parts by mass of the total mass of the saturated cycloalkyl (meth) acrylate monomer and the saturated chain-like alkyl (meth) acrylate monomer is determined. It is preferably 90 parts by mass or less.
As a result, it is possible to obtain a cured product having a better balance between electrical insulation performance and elongation performance.

The hydrocarbon structure of the saturated linear alkyl (meth) acrylate monomer may be any saturated linear alkyl structure.
Specifically, examples of the saturated linear alkyl (meth) acrylate monomer include n-heptyl (meth) acrylate, n-octyl (meth) acrylate, n-nonyl (meth) acrylate, and n-decyl (meth) acrylate. Examples thereof include tridecyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate.

The hydrocarbon structure of the saturated branched chain alkyl (meth) acrylate monomer may be a saturated branched chain alkyl structure, and may be an iso structure, a sec structure, a neo structure, or a tert structure.
Specifically, examples of the saturated branched chain alkyl (meth) acrylate monomer include isoheptyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Can be mentioned.
The saturated branched chain-like alkyl (meth) acrylate monomer has better solubility with the urethanization reaction product, and is easy to obtain a more uniform cured film. At least one of a meta) acrylate or an isodecyl (meth) acrylate is preferred.

The curable composition of the present embodiment may contain unreacted A component, B component, C component, and D component that have not undergone urethanization reaction. In addition, the curable composition of the present embodiment may contain a urethanization reaction catalyst formulated to promote the urethanization reaction.
As described above, the curable composition of the present embodiment contains various reaction products and unreacted substances. Therefore, it can be said that it is not practical to specify the molecular structure of all the contained compounds. In other words, it can be said that it is almost impractical to directly specify the structure or property of all the compounds contained in the curable composition of the present embodiment. However, since the molecular structure of the compound before the urethanization reaction has been specified and the product due to the urethanization reaction can be sufficiently predicted, it is not possible to predict the molecular structure of the reaction product (main reaction product, etc.). It is possible enough.

The curable composition of the present embodiment may further contain a photopolymerizable monomer, a photopolymerization initiator, etc. added after the urethanization reaction. Examples of the photopolymerizable monomer include the saturated cycloalkyl (meth) acrylate monomer described above and a photopolymerizable monomer that does not undergo a urethanization reaction other than the saturated chain alkyl (meth) acrylate monomer.

Examples of the above-mentioned photopolymerizable monomer that does not undergo a urethanization reaction include monofunctional (meth) acrylate monomers and polyfunctional (meth) acrylate monomers as described below.
Examples of the monofunctional (meth) acrylate monomer include phenyloxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, benzyl (meth) acrylate, and ethoxydiethylene glycol (meth) acrylate.
Examples of the polyfunctional (meth) acrylate monomer include neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polypropylene glycol di (meth) acrylate, and ethylene oxide. Modified Bisphenol A Di (Meta) Acrylate, Ethylene Oxide Modified Trimethylol Propantri (Meta) Acrylate, Ethylene Oxide Modified Pentaerythritol Tetra (Meta) Acrylate, Tris [(Meta) Acryloxyethyl] Isocyanurate, Ethylene Oxide Modified Dipentaerythritol Hexa (Meta) ) Acrylate, epoxy (meth) acrylate and the like can be mentioned.
These monomers may be used alone or in combination of two or more.
_{As the photopolymerizable monomer, a benzene ring and an ether bond (-CH 2-} O-CH _2- ), -OH group and -COOH group are used in that the weather resistance of the cured product after curing is improved. Monomers that do not contain any of the polar groups such as are preferred.

The photopolymerization initiator is not particularly limited as long as it is a compound that generates radicals by irradiated light (ultraviolet rays or the like). Examples of the photopolymerization initiator include an acetophenone-based photoinitiator, a benzoin-based photoinitiator, a benzophenone-based photoinitiator, a thioxanthone-based photoinitiator, and an acylphosphine oxide-based photoinitiator.
As the photopolymerization initiator, a commercially available product can be used.

When the curable composition of the present embodiment is cured not only by light irradiation but also by moisture (humidity) in the air, the curable composition of the present embodiment contains an isocyanate monomer further added after the urethanization reaction. But it may be.
Examples of the isocyanate monomer added after the urethanization reaction include aromatic diisocyanate monomers, alicyclic diisocyanate monomers, and aliphatic diisocyanate monomers. These monomers may have 2-4 isocyanate groups in the molecule.
Examples of the aromatic diisocyanate monomer include each monomer such as tolylene diisocyanate, diphenylmethane diisocyanate, diphenylpropane diisocyanate, triphenylmethane diisocyanate, phenylenedi isocyanate, xylylene diisocyanate, naphthalenedi isocyanate and trizine diisocyanate.
Examples of the alicyclic diisocyanate monomer include hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, cyclohexylylene diisocyanate, 3-isocyanatemethyl-3,5,5-trimethylcyclohexylisocyanate (isophorone diisocyanate), and the like. Examples of the aliphatic diisocyanate monomer include each monomer such as 3-isocyanate ethyl-3,5,5-trimethylcyclohexyl isocyanate and 3-isocyanate ethyl-3,5,5-triethylcyclohexylisocyanate, for example, hexamethylene diisocyanate monomer and the like. Can be mentioned.
The isocyanate monomer may be an adduct-modified product, a biuret-modified product, an isocyanurate-type product, or a polypeptide product of at least one of the above-mentioned monomers.
These monomers may be used alone or in combination of two or more.
As the isocyanate monomer, a monomer that does not contain a benzene ring and does not contain an unsaturated bond is preferable in that the weather resistance of the cured product after curing becomes better.

The curable composition of the present embodiment contains a compound having a benzene ring (aromatic hydrocarbon composed of 6 cyclic carbon atoms) in the molecule as a urethanization reaction product, a photopolymerizable monomer, and an isocyanate monomer. It is preferable not to include it.

The curable composition of the present embodiment may contain a photosensitizer, a polymerization inhibitor, an antioxidant, a dye, a pigment, a phosphor and the like, if necessary.
The curable composition of the present embodiment preferably does not contain a powder such as an inorganic powder or a resin powder.

The curable composition of the present embodiment preferably contains 10% by mass or more of the above-mentioned urethanization reaction product (compound group produced by the urethanization reaction). This allows it to be more fully cured by light irradiation and, in some cases, by moisture.
The curable composition of the present embodiment may contain 90% by mass or less of the above-mentioned urethanization reaction product.
The curable composition of the present embodiment may contain 10% by mass or more of the above-mentioned photopolymerizable monomer that does not undergo a urethanization reaction, or may contain 85% by mass or less.
When the curable composition of the present embodiment is designed to be cured by moisture, it may contain 2% by mass or more of isocyanate monomers further added after the urethanization reaction, or 20% by mass or less.

Subsequently, an embodiment of the method for producing a curable composition according to the present invention will be described.

In the method for producing a curable composition of the present embodiment, for example, a block having a poly (ethylene / ethylene / propylene) block structure and a polystyrene block structure in the molecule and having a hydroxy group at one end of the molecular chain is used. At least one selected from a polymer (the above A component), an isocyanurate form of an aliphatic diisocyanate having 6 to 10 total carbon atoms, an adduct modified form, and a biuret modified form (the above B component), and 2 or more and 4 or less. polyol compounds having a hydroxyl group in the molecule and (component (C)), and hydroxy saturated C ₁ -C ₄ alkyl (meth) acrylate (the D component), the urethanization reaction in the presence of the above urethane reaction A curable composition containing the product is produced.

Specifically, in the method for producing a curable composition of the present embodiment, the above-mentioned urethanization reaction is generated by the urethanization reaction in the presence of the above-mentioned A component, B component, C component, D component and a urethanization reaction catalyst. It is equipped with a reaction step for synthesizing a substance.
The method for producing a curable composition of the present embodiment further comprises an addition step of further adding a photopolymerizable monomer and a photopolymerization initiator (adding an isocyanate monomer further if necessary) after the reaction step.

The components A, B, C, D, and the urethanization reaction catalyst used in the reaction step are as described above.

In the above production method, in order to prevent a reaction with moisture, the reaction step is usually carried out after replacing the air in the reaction vessel with nitrogen.

In the reaction step, general reaction conditions suitable for the urethanization reaction can be adopted. Preferably, in the reaction step, the urethanization reaction is carried out by maintaining the temperature of 50 ° C. to 90 ° C. for 0.5 to 3 hours.

In the reaction step, the ratio (molar ratio) of the amounts of the preferable A component, B component, C component, and D component is as described above.

In the reaction step, a compound that is not involved in the urethanization reaction and that produces a polymerization reaction product by light irradiation may be further coexisted. Examples of such compounds include the above-mentioned photopolymerizable monomers.

In the addition step, after the urethanization reaction, the above-mentioned photopolymerizable monomer, photopolymerization initiator, and if necessary, isocyanate monomer may be further added. Further, since the photopolymerizable monomer and the isocyanate monomer to be added have a low viscosity, they play a role like a solvent for diluting the above-mentioned urethanization reaction product, but on the other hand, they themselves are cured by light or moisture. It also plays a role in curing the cured product more sufficiently. As the photopolymerizable monomer and the isocyanate monomer are further blended, the viscosity of the curable composition for curing is lowered, and the step of applying the curable composition can be simplified.

In the addition step, a photosensitizer, a polymerization inhibitor, an antioxidant, a dye, a pigment, a phosphor and the like may be further added, if necessary.

The curable composition of the present embodiment is used as a cured product cured by irradiation with light such as ultraviolet rays. For example, after applying the above-mentioned curable composition to an electronic circuit to be coated, the composition is cured by irradiating it with light such as ultraviolet rays to form a coating film of the cured product.
Depending on the case, the curing reaction due to the humidity in the air is further promoted by leaving it in the air for several hours to several days.

Ultraviolet rays can be used as the light to be irradiated to proceed with the curing reaction. As the light source, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp, an LED lamp and the like can be used. As the irradiation intensity, for example, 10 to 10,000 mW / cm ² can be adopted.

When further advancing the curing reaction by humidity, the temperature of the air to be left is preferably 20 to 40 ° C., and the humidity of the air is preferably 40 to 90 RH%.

Objects to which the above curable composition is coated and coated include, for example, electronic circuits and terminals on a mounting substrate used for precision equipment, and mounting for mounting on automobiles, bicycles, railways, aircraft, ships, and the like. Electronic circuits and terminals on the board, electronic circuits and terminals on the mounting board used for mobile devices (mobile phones, digital cameras, digital video cameras, etc.), boards used for outdoor devices (water heaters, air conditioner outdoor units, etc.) Examples thereof include electronic circuits and terminals of the above, electronic circuits and terminals on a mounting board used for water-related equipment such as washing machines, hot water washing toilet seats, and dishwashing dryers.

The curable composition of the present embodiment and the method for producing the composition are as illustrated above, but the present invention is not limited to the above-exemplified curable composition and the method for producing the composition.
That is, a general curable composition and various forms used in the method for producing the composition can be adopted as long as the effects of the present invention are not impaired.

Next, the present invention will be described in more detail by means of experimental examples, but the present invention is not limited thereto.

As described below, (A) to (D) were mixed to carry out a urethanization reaction to produce a curable composition containing a urethanization reaction product.

<Raw materials in the reaction process>
(A) Monool (denoted as SEEPS-OH), which is a branched polyolefin diol / styrene-ethylene / ethylene / propylene-styrene block copolymer.
Product name "Septon HG252" (manufactured by Kuraray)
(Contains 28% by mass of styrene, number average molecular weight 55,000)
: Isocyanurate derivative of hexamethylene diisocyanate (HMDI), a trifunctional polyisocyanate compound having three (B) isocyanate groups in the molecule, which has a -OH group at one end of the molecular chain Product name "DURANATE TPA-100: Isocyanate" Group content 23% by mass "manufactured by Asahi Kasei Co., Ltd. (C) A tetrafunctional polyol compound (polyhydric alcohol) having four -OH groups in the molecule.
・ Ditrimethylolpropane (commercially available)
(D) Hydroxy Saturated C _{1 to} C ₄ Alkyl (meth) Acrylate / 2-Hydroxyethyl Acrylate (Commercially available)
(others)
-Photopolymerizable Monomer A (Reaction Solvent / Diluent See below)
・ Urethane reaction catalyst (commercially available dibutyltin dilaurate)

<Raw materials in the addition process>
-Photopolymerizable monomer A
Saturated cycloalkyl (meth) acrylate monomer (isobornyl acrylate commercial product)
-Photopolymerizable monomer B (diluent)
Saturated chain alkyl (meth) acrylate monomer (Isononyl acrylate commercial product)
-Photopolymerization initiator Product name "IRGACURE 907" manufactured by IGMResins-Photosensitizer (2,4-diethylthioxanthone)
Product name "KAYACURE DETX-S" manufactured by Nippon Kayaku Co., Ltd.

(Example 1)
The urethanization reaction was carried out at 80 ° C. for 3 hours in the presence of the above (A), (B), (C), (D) and a catalyst at the blending amounts shown in Table 1, and the reaction step was carried out. ..
Next, the above raw materials were added to the composition after the reaction step at the blending amounts shown in Table 1 and mixed at 80 ° C. for 1 hour, and the addition step was carried out.
In this way, a curable composition was produced.

(Example 2)
A curable composition was produced in the same manner as in Example 1 except that the composition was changed to the composition shown in Table 1 in the addition step.

(Comparative example)
A curable composition was obtained in the same manner as in Example 1 except that the amount of component A shown in Table 1 was used without carrying out the reaction step.

Table 1 shows the compounding compositions for producing the curable compositions of Examples 1 and 2 and Comparative Examples.

As shown below, each curable composition produced in Examples and Comparative Examples was evaluated. Specifically, the viscosity of each curable composition produced, the tensile modulus, tensile elastic modulus, volume resistance, and dielectric breakdown strength of the cured product were investigated.
In general, the higher the volume resistance and the dielectric breakdown strength, the more sufficiently the curing progresses.

<Curing>
Each composition was applied to a tin plate having a size of 0.3 × 130 × 180 mm so that the thickness of the cured product after curing was 100 μm. Ultraviolet rays were irradiated with a 500 W UV lamp so that the integrated light intensity had ^{a light intensity of 3000 mJ / cm 2.}

<Tension elongation of cured product>
A cured product was formed on the release-treated PET film in the same manner as in the above-mentioned curing treatment. Next, the PET film was peeled off from the film-like cured product, and the cured product film was cut into a JIS dumbbell No. 2 shape. Then, the tensile elongation was measured under the measurement conditions of the distance between chucks: 20 mm and the crosshead speed: 300 mm / min.
The elongation rate (%) was calculated by the following formula.
Elongation rate (%) = (break elongation (mm) -20) / 20 × 100

<Tension elastic modulus of cured product>
For the cured product formed by the above-mentioned curing treatment, the slope S at which the tensile strength (N) / mutation elongation amount (mm) was maximized was determined, and the tensile elastic modulus was calculated by the following formula.
Tension modulus (MPa) =
S (tensile strength (N) / mutation elongation (mm)) / (thickness (mm) x width (mm) x 20

<Volume resistivity of cured product>
A paste-like silver conductive paint was applied in a circular shape (diameter 30 mm) on each cured product cured on the tin plate as described above. The upper electrode was formed by drying at 60 ° C. for 30 minutes. On the other hand, the tin plate used as the base material was used as the lower electrode. A voltage of 100 V DC was applied and the resistance value after 60 seconds was obtained. Then, the electrode area was multiplied by the resistance value and divided by the thickness of the cured product (cured film) to obtain the volume resistivity.

<Chemical breakdown voltage (BDV)>
The sphere of the sphere-plate electrode described in JIS C2110-1 was placed on a cured product formed on the tin plate to form an upper electrode. On the other hand, the tin plate was used as the lower electrode. An AC voltage of 60 Hz was applied, the voltage was increased so that dielectric breakdown occurred in 10 to 20 seconds, and the dielectric breakdown voltage value was measured. The measurements were carried out in oil. Further, the obtained value was divided by the thickness of the cured product (cured film) to obtain the dielectric breakdown value (kV / 0.1 mm) per 0.1 mm.

Table 2 shows the results of evaluating the cured product after curing as described above. The content ratio of the urethanization reaction product in Table 2 is a value calculated from the blending ratio after confirming that the yield of the urethanization reaction in the above reaction step is 100%.

As can be seen from the evaluation results shown in Table 2, the curable composition of the example was able to obtain a cured product having a higher dielectric breakdown strength than the curable composition of the comparative example. ..

The curable composition of the present invention is preferably used as a cured product, for example, in order to coat the electronic circuit with a cured product, after being applied to the electronic circuit and then irradiated with light to be cured. The curable composition of the present invention is suitably used, for example, as a curable composition for an insulating coating.

Claims (7)

A block copolymer having a polyolefin block structure and a polystyrene block structure in the molecule and having a hydroxy group at one end of the molecular chain,
Polyisocyanate compounds having multiple isocyanate groups in the molecule,
A polyol compound having multiple hydroxy groups in the molecule, and
A hydroxy (meth) acrylate having one (meth) acryloyl groups and one hydroxyl group and C ₁ -C ₄ saturated alkyl in the molecule,
A curable composition comprising the urethanization reaction product of. The curable composition according to claim 1, which comprises the urethanization reaction product having both the (meth) acryloyl group derived from the hydroxy (meth) acrylate and the isocyanate group derived from the polyisocyanate compound in the molecule. thing. The curable composition according to claim 1, wherein the urethanization reaction product does not have reactivity with the isocyanate group derived from the polyisocyanate compound. The curable composition according to any one of claims 1 to 3, wherein the polyolefin block structure of the block copolymer contains a random sequence structure of ethylene units and propylene units. The curable composition according to any one of claims 1 to 4, wherein the polyisocyanate compound has 2 or more and 4 or less of the isocyanate groups in the molecule. The curable composition according to any one of claims 1 to 5, wherein the polyol compound has 2 or more and 4 or less of the hydroxy groups in the molecule. A saturated cycloalkyl (meth) acrylate monomer having a saturated cyclic hydrocarbon structure and a (meth) acryloyl group in the molecule, and
A saturated chain alkyl (meth) acrylate monomer having a saturated chain hydrocarbon structure and a (meth) acryloyl group in the molecule, and
The curable composition according to any one of claims 1 to 6, further comprising.

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