JP2019218496A - Epoxy resin composition - Google Patents

Abstract

To provide an epoxy resin composition having excellent strength and durability even at high temperature.SOLUTION: An epoxy resin composition contains at least one epoxy resin, and a block urethane resin containing a polyol, a polyisocyanate, and a hindered phenolic compound having a tertiary butyl group.SELECTED DRAWING: None

Description

  The present invention relates to an epoxy resin composition.

  Conventionally, epoxy resin compositions have been widely used, for example, as adhesives for structural members of automobiles. For example, Patent Literature 1 and Patent Literature 2 describe an adhesive for a structural member of an automobile, including a resin composition containing an epoxy resin and a butyral resin.

JP-A-2-4887 JP-A-3-212474

  However, the adhesives described in Patent Literature 1 and Patent Literature 2 have insufficient adhesiveness. In particular, a cured product of a resin composition containing an epoxy resin is oxidatively decomposed by heat and oxygen at a high temperature, and thus has a problem that strength and durability are reduced.

  The present invention has been made in view of such conventional problems, and has as its object to provide an epoxy resin composition having excellent strength and durability even at high temperatures.

In order to achieve the above object, the epoxy resin composition of the present invention,
At least one epoxy resin;
Polyol, polyisocyanate, and a block urethane resin containing a hindered phenol compound having a tertiary butyl group,
It is characterized by including.

  An epoxy resin composition having excellent strength and durability even at high temperatures can be provided.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. However, the components described in the following embodiments are exemplifications, and are not intended to limit the technical scope of the present invention thereto.

  The present invention is an epoxy resin composition containing at least one kind of epoxy resin and block urethane resin as main components (hereinafter, referred to as a resin composition according to the present embodiment).

  Hereinafter, each component will be described in detail.

≪Epoxy resin≫
The epoxy resin which is one of the main components in the resin composition according to the present embodiment includes, for example, bisphenol A type, bisphenol F type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AF type, Bifunctional glycidyl ether type epoxy resins such as an epoxy compound having a bisphenyl group such as a biphenyl type, a polyalkylene glycol type, an alkylene glycol type epoxy compound, an epoxy compound having a naphthalene ring, and an epoxy compound having a fluorene group; Polyfunctional glycidyl ether type epoxy resins such as phenol novolak type, orthocresol novolak type, trishydroxyphenylmethane type and tetraphenylolethane type; glycidyl esters of synthetic fatty acids such as dimer acid Epoxy resin; glycidylamino such as N, N, N ', N'-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyl-m-xylylenediamine, triglycidyl-p-aminophenol, N, N-diglycidylaniline Aromatic epoxy resin having a group; epoxy compound having a tricyclodecane ring;

  The epoxy resin in the resin composition according to the present embodiment preferably contains a bisphenol A type epoxy resin and a carboxyl group-containing nitrile butadiene rubber-modified epoxy resin. Hereinafter, these epoxy resins will be described in detail.

<Bisphenol A type epoxy resin>
The bisphenol A type epoxy resin, which is one of the main components in the resin composition according to the present embodiment, will be described.

  The epoxy resin contained in the resin composition according to the present embodiment is a bisphenol A type epoxy resin having a bisphenol skeleton. By containing the bisphenol A type epoxy resin, a resin composition having sufficient strength as an adhesive can be obtained.

  The bisphenol A type epoxy resin according to the present embodiment preferably has an epoxy equivalent of 150 or more and 260 or less. Further, the amount of the bisphenol A type epoxy resin in the resin composition according to the present embodiment is preferably 20 to 80% by mass. When the content is in the above range, a resin composition having more excellent impact resistance can be obtained.

<Carboxyl group-containing nitrile butadiene rubber modified epoxy resin>
The carboxyl group-containing nitrile-butadiene rubber-modified epoxy resin, which is one of the main components in the resin composition according to the present embodiment, will be described.

  The resin composition according to the present embodiment includes an epoxy resin whose skeleton is rubber, and specifically includes an NBR (nitrile butadiene rubber) -modified epoxy resin containing a carboxyl group. By containing the NBR-modified epoxy resin, a resin composition having excellent heat resistance, impact resistance, and flexibility can be obtained.

  The NBR-modified epoxy resin according to the present embodiment preferably has an epoxy equivalent of 200 or more and 500 or less. Further, the amount of the NBR-modified epoxy resin in the resin composition according to the present embodiment is preferably 5 to 70% by mass. When the content is in the above range, a resin composition having more excellent impact resistance and flexibility can be obtained.

  The epoxy resin used when producing the NBR-modified epoxy resin is not particularly limited, and a conventionally known epoxy resin can be used. Further, one type of epoxy resin may be used alone, or two or more types may be used in combination.

  In the present invention, the epoxy equivalent and the addition amount of the NBR-modified epoxy resin are the epoxy equivalent and the addition amount in the NBR-modified epoxy resin containing an excess epoxy resin used in the production.

≪Block urethane resin≫
The resin composition according to the present embodiment contains a block urethane resin in which a urethane prepolymer obtained by reacting a polyhydroxy compound and a polyisocyanate compound is blocked with a hindered phenol compound having a tertiary butyl group. Since the hindered phenol compound having a tertiary butyl group has an antioxidant function, by containing a block urethane resin having the same, the cured product is suppressed from being oxidized and decomposed by heat and oxygen even at a high temperature. . Further, by containing the hindered phenol compound having a tertiary butyl group, the compatibility with other resin components to be blended is improved, and the toughness of the cured product is improved.

<Polyhydroxy compound>
The polyhydroxy compound is not particularly limited in molecular weight and skeleton as long as it is a compound having two or more hydroxyl groups, and relatively low-molecular-weight polyhydric alcohols, polyether polyols, polyester polyols, other polyols, and These mixed polyols are exemplified.

  Specific examples of polyhydric alcohols include ethylene glycol (EG), diethylene glycol, propylene glycol (PG), dipropylene glycol, (1,3- or 1,4-) butanediol, pentanediol, Low-molecular-weight polyols such as pentyl glycol, hexanediol, cyclohexanedimethanol, glycerin, trimethylolpropane (TMP), 1,2,5-hexanetriol and pentaerythritol; and saccharides such as sorbitol.

  As the polyether polyol and the polyester polyol, those derived from the above-mentioned polyhydric alcohols or those derived from the following aromatic diols and amines may be used.

  Specific examples of the aromatic diols include, for example, resorcinol (m-dihydroxybenzene), xylylene glycol, 1,4-benzenedimethanol, styrene glycol, 4,4'-dihydroxyethylphenol; Bisphenol A structure (4,4'-dihydroxyphenylpropane), bisphenol F structure (4,4'-dihydroxyphenylmethane), brominated bisphenol A structure, hydrogenated bisphenol A structure, bisphenol S structure, bisphenol AF structure bisphenol Those having a skeleton;

  Specific examples of the amines include ethylenediamine and hexamethylenediamine, and specific examples of the alkanolamines include ethanolamine and propanolamine.

  Examples of the polyether polyol include, for example, at least one selected from the polyhydric alcohols, the aromatic diols, and the compounds exemplified as the amines, ethylene oxide, propylene oxide, butylene oxide (tetramethylene oxide), and tetrahydrofuran. And polyols obtained by adding at least one selected from alkylene oxides and styrene oxides.

  Specific examples of such polyether polyols include polyethylene glycol, polypropylene glycol (PPG), polypropylene triol, ethylene oxide / propylene oxide copolymer, polytetramethylene glycol (PTMG), polytetraethylene glycol, sorbitol-based polyol, and the like. Is mentioned.

  Similarly, examples of the polyester polyol include a condensate of any of the above-mentioned polyhydric alcohols, the above-mentioned aromatic diols, and the above-mentioned amines with a polybasic carboxylic acid; a lactone-based polyol; a polycarbonate polyol; . As the lactone-based polyol, specifically, for example, those obtained by ring-opening polymerization of a lactone such as ε-caprolactone, α-methyl-ε-caprolactone, ε-methyl-ε-caprolactone with a suitable polymerization initiator. Those having a hydroxyl group at both terminals are exemplified.

  Specific examples of other polyols include acrylic polyols; polybutadiene polyols; and polymer polyols having a carbon-carbon bond in the main chain skeleton, such as hydrogenated polybutadiene polyol.

  One of these polyhydroxy compounds may be used alone, or two or more thereof may be used in combination.

<Polyisocyanate compound>
The polyisocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups, and examples thereof include aliphatic polyisocyanate, aromatic polyisocyanate, and alicyclic polyisocyanate.

  Specific examples of the polyisocyanate compound include aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, and norbornane diisocyanate (NBDI); Tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI)), MDI (for example, 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4 '-Diphenylmethane diisocyanate (2,4'-MDI)), 1,4-phenylene diisocyanate, polymethylene polyphenylene polyisocyanate, xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate Aromatic polyisocyanates such as thiol (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalenediisocyanate (NDI) and triphenylmethane triisocyanate; transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI); Alicyclic polyisocyanates such as bis (isocyanatemethyl) cyclohexane (H6XDI) and dicyclohexylmethane diisocyanate (H12MDI) are exemplified. One of these polyisocyanate compounds may be used alone, or two or more thereof may be used in combination.

<Hindered phenol compound having tertiary butyl group>
By the reaction of the polyhydroxy compound with the polyisocyanate, a urethane prepolymer containing a free isocyanate group at a terminal can be obtained. By reacting the urethane prepolymer with a hindered phenol compound having a tertiary butyl group described below, a blocked urethane resin blocked by the hindered phenol can be obtained.

  Conventionally, as a blocking agent for urethane prepolymers, there was a block urethane resin using an amine monomer as a blocking agent, but the amine monomer promotes self-polymerization of an epoxy group, and thus has a problem of poor storage stability. Had a point. In this embodiment, a hindered phenol having a tertiary butyl group is used as a blocking agent. Since a hindered phenol having a tertiary butyl group has an antioxidant function, an epoxy resin composition having excellent strength and durability even at a high temperature can be obtained by containing a block urethane resin having the hindered phenol.

  Examples of the hindered phenol having a tertiary butyl group include 2-tert-butyl-p-cresol, 2,6-di-tert-butyl-4-methylphenol (dibutylhydroxytoluene), and 2,6-di-tert. -Butyl-4-ethylphenol, 2,2'-methylenebis (4ethyl-6-tert-butylphenol), 2,2'-methylenebis (4methyl-6-tert-butylphenol), 4,4'-butylidenebis (3 -Methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 2,5-di-tert-butylhydroquinone, triethylene glycol-bis- [3- (3 -T-butyl-5-methyl-4hydroxyphenyl) propionate], 1,6 Hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di -T-butylanilino) -1,3,5-triazine, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [ 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylene Bis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 3,5-di-t-butyl-4-hydroxy-benzylphosphonate-die Ester, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, bis (3,5-di-tert-butyl-4-hydroxy) Ethyl benzylphosphonate) calcium, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, N, N'-bis [3- (3,5-di-tert-butyl-4-) Hydroxyphenyl) propionyl] hydrazine, tris (2,4-di-t-butylphenyl) phosphite, 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-t -Butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole Sol, 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, bis (2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate (1,2,2,6,6-pentamethyl-4-piperidyl), 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate and the like. One of these hindered phenol compounds may be used alone, or two or more thereof may be used in combination.

  The amount of the hindered phenol compound to be added is preferably 5 to 30% by mass based on the total amount of the polyhydroxy compound and the polyisocyanate compound.

<Catalyst>
Catalysts suitable for the reaction to synthesize the block urethane resins are commercially available, for example, metal- or transition metal compounds based on aluminum, tin, zinc, titanium, manganese, bismuth or zirconium, such as dibutyltin dilaurate, zinc Octoate, titanium tetrabutyrate or zirconium octoate may, for example, be mentioned.

  Further, the amount of the block urethane resin in the resin composition according to the present embodiment is preferably 3 to 50% by mass. When the content is in the above range, a resin composition having excellent strength and durability even at a high temperature can be obtained.

≪Other ingredients≫
The resin composition according to the present embodiment contains, as components other than the main components described above, other components such as a curing agent and a curing accelerator described below. Each component is described in detail below.

<Curing agent>
As the curing agent according to the present embodiment, those usually used as curing agents for epoxy resins can be used as they are.

  Specific examples of the curing agent include, for example, dicyandiamide, 4,4′-diaminodiphenylsulfone, imidazole derivatives such as 2-n-heptadecyl imidazole, isophthalic dihydrazide, N, N-dialkyl urea derivatives, Examples thereof include alkylthiourea derivatives, acid anhydrides such as tetrahydrophthalic anhydride, isophoronediamine, m-phenylenediamine, N-aminoethylpiperazine, melamine, guanamine, boron trifluoride complex compound, and trisdimethylaminomethylphenol. One of these may be used alone, or two or more may be used in combination.

  Among the above curing agents, dicyandiamide can be suitably used. Dicyandiamide is a latent curing agent that can be stably stored at room temperature, and has a function of being rapidly cured by being melted and activated by heating. Therefore, by using dicyandiamide, a resin composition having excellent strength and durability even at high temperatures can be obtained.

  The content of the curing agent in the resin composition according to the present embodiment is not particularly limited, and an optimal amount for each curing agent can be preferably used.

<Curing accelerator>
The curing accelerator according to the present embodiment has an effect of accelerating the curing reaction of dicyandiamide suitably used as a curing agent. The curing accelerator used in the composition of the present embodiment is not particularly limited as long as it has an effect of accelerating the curing reaction of dicyandiamide, and a conventionally known curing accelerator can be used. Specific examples of the curing accelerator include aliphatic dimethyl urea and aromatic dimethyl urea. One of these curing accelerators may be used alone, or two or more thereof may be used in combination.

<Further components>
The resin composition according to the present embodiment may further contain an inorganic filler, an organic or polymer filler, a flame retardant, an antistatic agent, a conductivity-imparting agent, a lubricant, a slidability-imparting agent, and a surface activity, depending on its use. Agents, coloring agents and the like. These may be used alone or in combination of two or more. Specific examples of other components include calcium carbonate, talc, wallest night, fumed silica, aluminum hydroxide, calcium oxide, bentonite, kaolin, carbon black, and the like.

<< Production method of epoxy resin composition >>
The method for producing the resin composition according to the present embodiment is not particularly limited, and can be produced by a conventionally known method. For example, it can be obtained by kneading a bisphenol A-type epoxy resin, an NBR-modified epoxy resin, a block urethane resin, and other components as necessary at room temperature.

<< Example >>
Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

(Synthesis of block urethane resin of Example 1)
1000 parts by weight of a glycerin-based polyether polyol (hydroxyl equivalent: 1000) was charged, and 221 parts by weight of isophorone diisocyanate was charged by replacing the atmosphere with nitrogen. The mixture was heated to 80 ° C., 0.01 part by weight of dibutyltin dilaurate was charged as a catalyst, and reacted at a temperature of 80 to 90 ° C. for 3 hours.

  Next, 220 parts by weight of dibutylhydroxytoluene was charged and reacted at a temperature of 80 to 90 ° C. for 3 hours. The disappearance of NCO absorption was confirmed by an infrared spectrophotometer (IR), and a block urethane resin (BUR-1) of Example 1 was obtained.

(Synthesis of block urethane resin of Example 2)
As a polyether polyol, 1,000 parts by weight of polytetramethylene glycol (hydroxyl equivalent: 1000) was charged, and the upper part of nitrogen was replaced, and 221 parts by weight of isophorone diisocyanate was charged. The mixture was heated to 80 ° C., 0.01 part by weight of dibutyltin dilaurate was charged as a catalyst, and reacted at a temperature of 80 to 90 ° C. for 3 hours.

  Next, 164 parts by weight of 2-tert-butyl-p-cresol was charged and reacted at a temperature of 80 to 90 ° C. for 3 hours. The disappearance of NCO absorption was confirmed by an infrared spectrophotometer (IR), and a block urethane resin (BUR-2) of Example 2 was obtained.

(Synthesis of Block Urethane Resin of Comparative Example 1)
1000 parts by weight of a glycerin-based polyether polyol (hydroxyl equivalent: 1000) was charged, and the upper part of nitrogen was replaced, and 221 parts by weight of isophorone diisocyanate was charged. The mixture was heated to 80 ° C., 0.01 part by weight of dibutyltin dilaurate was charged as a catalyst, and reacted at a temperature of 80 to 90 ° C. for 3 hours.

  Next, 94 parts by weight of phenol was charged and reacted at a temperature of 80 to 90 ° C. for 3 hours. It was confirmed with an infrared spectrophotometer (IR) that the absorption of NCO had disappeared, and a block urethane resin (BURX-1) of Comparative Example 1 was obtained.

(Synthesis of Block Urethane Resin of Comparative Example 2)
1000 parts by weight of a glycerin-based polyether polyol (hydroxyl equivalent: 1000) was charged, and the upper part of nitrogen was replaced, and 221 parts by weight of isophorone diisocyanate was charged. The mixture was heated to 80 ° C., 0.01 part by weight of dibutyltin dilaurate was charged as a catalyst, and reacted at a temperature of 80 to 90 ° C. for 3 hours.

  Next, 181 parts by weight of dicyclohexylamine was charged and reacted at a temperature of 80 to 90 ° C. for 3 hours. It was confirmed by an infrared spectrophotometer (IR) that the absorption of NCO had disappeared, and a block urethane resin (BURX-2) of Comparative Example 2 was obtained.

(Production of epoxy resin composition in each example and each comparative example)
Using a predetermined amount of bisphenol A type epoxy resin, NBR modified epoxy resin, block urethane resin, dicyandiamide, 1-phenyl-3,3-dimethylurea and fumed silica, these are uniformly kneaded, and An epoxy resin composition of each comparative example was obtained. In addition, in Comparative Examples 3 and 4, the addition amount of the block urethane resin (BUR-1) was set to 2% by mass and 60% by mass, respectively, based on the epoxy resin composition. The amount (parts by weight) of each component is as shown in Table 1.

(Evaluation)
The composition obtained in each of Examples and Comparative Examples was applied to the surface of a mild steel sheet and cured at a predetermined temperature (180 ° C. or 210 ° C.) for a predetermined time (30 minutes). It was subjected to a T-type peel strength test. The test was performed under the following conditions.

Tensile shear strength test: According to JIS K-6850 Test speed 5 mm / min
Coating thickness 0.2mm
Coating area 12.5 × 25mm
T-type peel strength test: in accordance with JIS K-6854 Test speed 100 mm / min
Coating thickness 0.2mm
Coating area 25 × 100mm
Table 1 shows other conditions.

  Table 1 shows the results of each evaluation.

In each of the examples, the tensile shear strength and the T-peel strength were good at both the curing temperatures of 180 ° C. and 210 ° C. On the other hand, in Comparative Examples 1 and 2, which did not contain a block urethane resin containing a hindered phenol compound having a tertiary butyl group, the strength was lower than that of the Examples at a high curing temperature of 210 ° C. Therefore, it was found that the epoxy resin compositions in Examples have excellent strength even at high temperatures.
In addition, Comparative Example 3 in which the content of the block urethane resin was below the lower limit of 3 to 50% by mass of the epoxy resin composition and Comparative Example 4 in which the content was higher than the upper limit were regarded as examples in all the strength tests performed. On the other hand, the strength was low.

  Further, the initial viscosities of the epoxy resin compositions of the examples and comparative examples were measured. Next, the epoxy resin composition was stored in a constant temperature bath at 40 ° C. for 2 weeks. The viscosity of the epoxy resin composition after storage was measured, and the viscosity increase was calculated.

  Table 1 shows the results of each evaluation.

  All of the epoxy resin compositions of the examples have excellent storage stability. Comparative Examples 1, 3 and 4 have the same storage stability as the present invention, but Comparative Example 2 is inferior in storage stability.

Claims (6)

At least one epoxy resin;
Polyol, polyisocyanate, and a block urethane resin containing a hindered phenol compound having a tertiary butyl group,
An epoxy resin composition comprising:
However, the content of the block urethane resin is 3 to 50% by mass based on the epoxy resin composition. The epoxy resin includes a bisphenol A type epoxy resin,
The epoxy resin composition according to claim 1. The epoxy resin includes a carboxyl group-containing nitrile butadiene rubber-modified epoxy resin,
The epoxy resin composition according to claim 1. The epoxy resin composition further comprises dicyandiamide,
The epoxy resin composition according to claim 1. The epoxy resin composition further contains a urea-based catalyst as a curing accelerator for the dicyandiamide,
The epoxy resin composition according to claim 4. The epoxy resin composition further comprises one or more compounds selected from calcium carbonate, talc, wallestonite, fumed silica, aluminum hydroxide, calcium oxide, bentonite, kaolin, carbon black,
The epoxy resin composition according to claim 1.