JP2013091687A - Epoxy resin having specific polyglycerol structure and epoxy resin composition including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin having a specific polyglycerol structure and exhibiting excellent heat resistance and curability, and an epoxy resin composition using the epoxy resin and giving a cured product less colored after curing and excellent in flexibility when cured.SOLUTION: The epoxy resin is obtained by reacting polyglycerol, wherein a total concentration of triglycerol and tetraglycerol is ≥60 wt.%, with epihalohydrin. The epoxy resin composition includes the epoxy resin.

Description

  The present invention relates to an epoxy resin having a specific polyglycerin structure and an epoxy resin composition obtained by using the epoxy resin.

  Conventionally, epoxy resins have excellent adhesiveness, mechanical properties, heat resistance, chemical resistance, electrical properties, etc., so various types of materials such as adhesives, paints, civil engineering and building materials, electrical / electronic component materials, insulating materials, etc. Used in various fields. Epoxy resin curing systems generally use room temperature curing or heat curing with curing agents such as amines, carboxylic acids, acid anhydrides, alcohols, etc., but in recent years, productivity, miniaturization, energy savings and higher performance have been achieved. Accompanying this, attention has been paid to a light curing or thermosetting system by cationic polymerization.

  When the epoxy resin is cured by cationic polymerization, the glycidyl ether type epoxy resins tend to be poor in curability unless they are multifunctional, although they are abundant. On the other hand, although the alicyclic epoxy resin has good curability, there is a problem that the cured product is brittle and easily cracks (Patent Document 1). Conventionally, epoxy resins having a polyglycerin structure have been commercially available for these problems. However, because of the polyfunctionality, the curability is relatively high, but the conventional product has a wide molecular weight distribution of polyglycerin. The heat resistance was poor and there was a problem with coloring after curing.

JP 59-54277 A

  An object of the present invention is to obtain an epoxy resin having a specific polyglycerin structure excellent in heat resistance and curability, and a cured product having a small color after curing and excellent in flexibility when cured using the epoxy resin. The object is to provide an epoxy resin composition.

  As a result of intensive studies to solve the above problems, the present inventors have obtained an epoxy resin obtained by a reaction of polyglycerin and epihalohydrin in which the total of triglycerin concentration and tetraglycerin concentration is 60% by weight or more, and The epoxy resin composition characterized by containing a compound has led to the solution of the above problems.

  The epoxy resin having a specific polyglycerin structure of the present invention has high heat resistance and excellent curability, and the epoxy resin composition containing the compound has small color after curing and excellent flexibility. A cured product is obtained.

  In the present invention, an epoxy resin having a specific polyglycerin structure is used, but polyglycerin as a raw material will be described.

  The polyglycerin used in the epoxy resin having a specific polyglycerin structure of the present invention is synthesized by using a dehydration condensation reaction of glycerin, a glycerin related substance such as glycidol, epichlorohydrin, glycerin halohydrin, or glycerin of synthetic glycerin. Although it can be obtained by recovery from the distillation residue, etc., it is generally obtained by adding a small amount of an alkali catalyst to glycerin and heating it to a high temperature of 200 ° C. or higher, and polycondensating it while removing the generated water. In the reaction, high polymers are sequentially formed by sequential intermolecular dehydration reaction, but the reaction composition is not uniform, and it becomes a complex mixed product such as unreacted glycerin, diglycerin, triglycerin, tetraglycerin. The higher the reaction temperature or the longer the reaction time, the more the reaction shifts to the higher molecular weight side. In addition, since unreacted glycerin can be distilled by vacuum distillation and diglycerin can be distilled by molecular distillation, diglycerin is generally used as a high-purity product and has a degree of polymerization higher than that. As the glycerin, a complex mixture of other components and a residue obtained by distilling glycerin and diglycerin are used.

  As an example, the polyglycerin composition is analyzed by weighing about 0.5 g of a polyglycerin sample and about 0.05 g of methyl palmitate (first grade reagent; Kishida Chemical) as an internal standard substance, and pyridine (special grade reagent; Chemistry) Dissolve these in about 1.8 ml, and then inject 0.2 ml of TMS-HT (reagent; Tokyo Chemical Industry) into 20 μl of this solution. It is determined by using it.

Gas chromatograph: GC-14B (manufactured by Shimadzu Corporation)
Column: OV-1 (manufactured by GL Sciences, inner diameter 3 mm, length 1.5 m)
Column temperature: 100 ° C. to 350 ° C. (temperature increase rate 10 ° C./min)
Carrier gas: Nitrogen (50 ml / min)
Injection part temperature: 350 ° C
Detector temperature: 350 ° C
Detector: FID

  The polyglycerin used in the epoxy resin having a specific polyglycerin structure of the present invention has a total of triglycerin concentration and tetraglycerin concentration in the polyglycerin composition of 60% by weight or more, preferably 65% by weight or more. Preferably it is 70 weight% or more. When polyglycerin of less than 60% by weight is used, an epoxy resin having a polyglycerin structure with a wide molecular weight distribution is obtained, and it is difficult to satisfy all the performances such as heat resistance and curability.

  Furthermore, the polyglycerin used for the epoxy resin having a specific polyglycerin structure of the present invention is the concentration of each of triglycerin and tetraglycerin with respect to polyglycerin having a total of triglycerin concentration and tetraglycerin concentration of 60% by weight or more. Is preferably in the range of 10 wt% to 70 wt%, and more preferably in the range of 20 wt% to 70 wt%. When polyglycerin having a composition outside these lower limits is used, it becomes an epoxy resin having a polyglycerin structure with a wide molecular weight distribution as described above, and it is difficult to satisfy all the performances such as heat resistance and curability. . Further, when polyglycerin having a composition outside the upper limit range is used, a plurality of distillation steps are required to produce it, which is not preferable because it becomes very uneconomical.

  In addition, the polyglycerin used in the epoxy resin having a specific polyglycerin structure of the present invention has a diglycerin concentration of less than 10% by weight and a polyglycerin concentration of hexaglycerin or more of less than 15%. Is desirable. When polyglycerin having a diglycerin concentration outside the range is used, it is not preferable because the heat resistance of the resulting epoxy resin having a polyglycerin structure is lowered. Moreover, when the polyglycerin density | concentration beyond hexaglycerin remove | deviates from the range, the viscosity of the epoxy resin which has the polyglycerin structure obtained will raise, and workability | operativity will worsen.

  The epoxy resin having a specific polyglycerin structure of the present invention can be produced by a known method, and can be obtained by reacting a specific polyglycerin with an epihalohydrin. This is a two-stage reaction method in which an addition reaction is performed using an amine or a Lewis acid catalyst in an inert solvent such as toluene or xylene, and then a ring-closing reaction is performed using an alkali such as NaOH, It can be produced using a method of reacting directly in one step with an alkali in an epihalohydrin solvent. Examples of the epihalohydrin used in this reaction include epichlorohydrin, epibromohydrin, epiiodohydrin, and the like. Epichlorohydrin that is industrially available and inexpensive is preferable.

  The epoxy resin composition of the present invention is characterized by containing an epoxy resin having a specific polyglycerin structure, but the epoxy resin used in the present invention may be cured alone, or other known epoxy You may use resin individually or in combination of 2 or more types. As long as performance, such as heat resistance, sclerosis | hardenability, coloring after a hardening, and a softness | flexibility, is not impaired with respect to a resin composition, it can use together in arbitrary ratios.

  Examples of the curing agent contained in the epoxy resin composition of the present invention include a cationic polymerization initiator that can be cured by heating or irradiation with active energy rays after blending, and an acid anhydride curing that can be cured at room temperature or by heating after blending. Agents, amine-based curing agents, phenol-based curing agents, latent curing agents, and the like. Among these, a cationic polymerization initiator is preferable in consideration of workability in handling the compounded resin composition and characteristics after curing.

  As the cationic polymerization initiator, at least one cation selected from aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium and the like, and at least one anion selected from BF4-, PF6-, and SbF6- Onium salts composed of Such a cationic polymerization initiator may be used individually by 1 type, and may use 2 or more types together.

  Specific examples of the aromatic sulfonium salt-based cationic polymerization initiator include bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluoroantimonate. Bis [4- (diphenylsulfonio) phenyl] sulfide bistetrafluoroborate, bis [4- (diphenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, (2-ethoxy-1-methyl-2-oxoethyl) ) Methyl-2-naphthalenylsulfonium hexafluorophosphate, (2-ethoxy-1-methyl-2-oxoethyl) methyl-2-naphthalenylsulfonium hexafluoroantimonate, (2-ethoxy-1-methyl) -2-oxoethyl) methyl-2-naphthalenylsulfonium tetrafluoroborate, (2-ethoxy-1-methyl-2-oxoethyl) methyl-2-naphthalenylsulfonium tetrakis (pentafluorophenyl) borate, diphenyl-4- (Phenylthio) phenylsulfonium hexafluorophosphate, diphenyl-4- (phenylthio) phenylsulfonium hexafluoroantimonate, diphenyl-4- (phenylthio) phenylsulfonium tetrafluoroborate, diphenyl-4- (phenylthio) phenylsulfonium tetrakis (pentafluorophenyl) ) Borate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, tripheny Sulfonium tetrafluoroborate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bishexafluoroantimonate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bistetrafluoroborate Bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate and the like.

  Specific examples of aromatic iodonium salt-based cationic polymerization initiators include diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis (pentafluorophenyl) borate, bis (dodecylphenyl) Iodonium hexafluorophosphate, bis (dodecylphenyl) iodonium hexafluoroantimonate, bis (dodecylphenyl) iodonium tetrafluoroborate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate, 4-methylphenyl-4- (1- Methylethyl) phenyliodonium hexafluorophosphate, 4-methylphenyl- -(1-methylethyl) phenyliodonium hexafluoroantimonate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium tetrafluoroborate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium tetrakis ( Pentafluorophenyl) borate and the like.

  Specific examples of the aromatic diazonium salt-based cationic polymerization initiator include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, phenyldiazonium tetrakis (pentafluorophenyl) borate and the like.

  Specific examples of the aromatic ammonium salt cationic polymerization initiator include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2-cyanopyridinium tetra Fluoroborate, 1-benzyl-2-cyanopyridinium tetrakis (pentafluorophenyl) borate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluorophosphate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluoroantimonate, Examples include 1- (naphthylmethyl) -2-cyanopyridinium tetrafluoroborate, 1- (naphthylmethyl) -2-cyanopyridinium tetrakis (pentafluorophenyl) borate, and the like.

  The content of the cationic polymerization initiator is preferably in the range of 0.1 to 15 parts by weight with respect to 100 parts by weight of the entire epoxy resin, and 0.3 to 7 weights in view of curability and physical properties of the cured product. More preferred is the range of parts.

  Specific examples of the acid anhydride curing agent in the present invention include tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic acid anhydride, hydrogenated methylnadic acid anhydride. , Trialkyltetrahydrophthalic anhydride, cyclohexanetricarboxylic anhydride, methylcyclohexenetetracarboxylic dianhydride, maleic anhydride, phthalic anhydride, succinic anhydride, dodecenyl succinic anhydride, pyromellitic anhydride, trimellitic anhydride Benzophenone tetracarboxylic acid, ethylene glycol bisanhydro trimellitate, glycerin bis (anhydro trimellitate) monoacetate and the like.

  The content of the acid anhydride-based curing agent is preferably in the range of 0.5 to 1.5 equivalents with respect to 1 equivalent of the epoxy group of the entire epoxy resin. A range of 8 to 1.2 equivalents is more preferable.

  Specific examples of the amine curing agent in the present invention include polyoxyethylene diamine, polyoxypropylene diamine, polyoxybutylene diamine, polyoxypentylene diamine, polyoxyethylene triamine, polyoxypropylene triamine, polyoxybutylene triamine, polyoxy Pentylenetriamine, diethylenetriamine <DETA>, triethylenetetramine <TETA>, tetraethylenepentamine <TEPA>, m-xylenediamine <MXDA>, trimethylhexamethylenediamine <TMD>, 2-methylpentamethylenediamine <2-MPMDA >, Diethylaminopropylamine <DEAPA>, isophoronediamine <IPDA>, 1,3-bisaminomethylcyclohexane <1,3-BAC>, bis ( -Aminocyclohexyl) methane <PACM>, norbornenediamine <NBDA>, 1,2-diaminocyclohexane <1,2-DCH>, laromine C-260, diaminodiphenylmethane <DDM>, metaphenylenediamine <MPDA>, diaminodiphenyl sulfone <DDS>, N-aminoethylpiperazine <N-AEP> and the like. These modified products, for example, MXDA modified products, IPDA modified products, etc. may be used.

  The content of the amine curing agent is preferably in the range of 0.5 to 1.5 equivalents with respect to 1 equivalent of the epoxy group of the entire epoxy resin, and 0.8 to 0.8 in view of curability and physical properties of the cured product. A range of 1.2 equivalents is more preferable.

  Specific examples of the phenol-based curing agent in the present invention include phenol novolac resins using various phenols as raw materials, xylylene skeleton-containing phenol novolac resins, dicyclopentadiene skeleton-containing phenol novolac resins, biphenyl skeleton-containing phenol novolac resins, and fluorene skeleton-containing phenols. Examples thereof include novolak resins and terpene skeleton-containing phenol novolac resins. The various phenols used above include bisphenol A, bisphenol F, bisphenol S, bisphenol AP, bisphenol C, bisphenol E, bisphenol Z, biphenol, tetramethylbisphenol A, dimethyl bisphenol A, tetramethyl bisphenol F, dimethyl bisphenol F, Fluorene skeletons such as tetramethylbisphenol S, dimethylbisphenol S, tetramethyl-4,4′-biphenol, trishydroxyphenylmethane, resorcinol, hydroquinone, pyrogallol, diisopropylidene, 1,1-di-4-hydroxyphenylfluorene, etc. Phenols, phenolic polybutadienes, phenols, cresols, ethylphenols, butylphenols, octets Le phenols, naphthols, and the like.

  The content of the phenolic curing agent is preferably in the range of 0.5 to 1.5 equivalents with respect to 1 equivalent of the epoxy group of the entire epoxy resin, and considering the curability and physical properties of the cured product, 0.8 to A range of 1.2 equivalents is more preferable.

  Specific examples of the latent curing agent include dicyandiamide, imidazole compound, dihydrazide compound, amine adduct-based latent curing agent, ketimine compound and the like. These latent curing agents are preferable because they can be stored for a long time in a state of being mixed with an epoxy resin in advance, and are easy to handle.

  The content of the latent curing agent is preferably in the range of 1 to 30 parts by weight with respect to 100 parts by weight of the entire epoxy resin, and in the range of 5 to 20 parts by weight in view of curability and physical properties of the cured product. More preferably.

  In the epoxy resin composition of the present invention, if necessary, a colorant, an antioxidant, a leveling agent, a surfactant, an ultraviolet absorber, a silane coupling agent, an inorganic filler, resin particles, a wettability improver, Additives such as antifoaming agents, light stabilizers and heat stabilizers; inorganic fillers such as calcium carbonate, talc, silica and barium sulfate can be used in combination.

  The epoxy resin composition of the present invention can be cured by normal temperature or heating, but can also be cured by irradiation with active energy rays. An active energy ray is a general term for electron beams, X-rays, ultraviolet rays, electron beams with high energy such as visible light in a low wavelength region, or electromagnetic waves, and ultraviolet rays are preferable because of the simplicity and spread of ordinary devices. There are many types of devices that can irradiate ultraviolet rays, but they can be arbitrarily selected. Moreover, it is also possible to use a blue LED as energy such as visible light on the low wavelength region side.

  Hereinafter, the present invention will be specifically described by way of examples. In addition, this invention is not limited to a following example. In addition, the polyglycerol used this time used the polyglycerol AH shown to the following synthesis example. However,% is based on weight.

<Synthesis example of polyglycerin A to H>
Purified glycerin (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) and sodium hydroxide as a catalyst were added to a reaction vessel equipped with a thermometer and a stirrer, and reacted at 250 ° C. under a nitrogen stream to obtain a polyglycerin composition. . Subsequently, this composition was distilled under reduced pressure to obtain polyglycerin compositions A to F shown in Table 1. In addition, polyglycerol G and H were obtained as what does not implement a vacuum distillation process.

<Synthesis Examples A1 to H1 of Epoxy Resin>
A reactor equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, and a nitrogen introduction tube was charged with 200 g of polyglycerin A and 400 g of toluene, and 1 g of boron trifluoride ether complex was added with stirring. While maintaining the internal temperature at about 60 ° C., 300 g of epichlorohydrin was dropped over about 3 hours with a dropping funnel, and the mixture was further stirred for 30 minutes. Next, 90 g of solid sodium hydroxide is added over 2 hours at the same temperature, and further aging is carried out for 1 hour at the same temperature. After the formed salt is removed by a water separation operation, the water separation operation is repeated several times. It was. Thereafter, toluene was distilled off under reduced pressure to obtain a polyglycerol epoxy resin A1. Similarly, polyglycerol epoxy resins (B1 to H1) were synthesized by changing the types of polyglycerol (B to H). However, for the synthesis using polyglycerol F and H, the amount of epichlorohydrin was changed to 400 g and 250 g, respectively.

  Examples 1 to 5 and Comparative Examples 1 to 4 were prepared in such a manner as shown in Table 2 (numbers indicate parts by weight) and the components were mixed so that the cationic polymerization initiator dissolved and became uniform. Various evaluations were made. The measurement of the thermogravimetric temperature as an index of heat resistance was evaluated before the cationic polymerization initiator was blended. Evaluation in the examples was performed by the following method.

  Thermal weight reduction temperature (heat resistance): Td1 (1% weight reduction temperature) and Td5 (5% weight reduction temperature) were measured using TG-DTA8120 (manufactured by Rigaku Corporation) as the thermal weight reduction temperature of various epoxy resins. .

Curability: The prepared composition was poured into a mold (50 mm × 50 mm × depth 5 mm) and heated over 90 ° C. × 3 hours + 120 ° C. × 3 hours to evaluate curability.
○: Completely cured under the above curing conditions.
X: Not completely cured under the above curing conditions.

Flexibility: 90 ° C. × 3 hours + 150 ° C. × 3 hours was heat-cured, and the flexibility was evaluated by the presence or absence of cracks in the cured product and the presence or absence of cracks when removed from the mold.
○: No cracks were observed in the cured product, and no cracks occurred when removed from the mold.
Δ: No cracks are observed in the cured product, but there are cracks when removed from the mold.
X: Cracks are observed in the cured product.

  Coloring after curing: The yellowness (YI: yellow index) of the cured product cured in the same manner as for flexibility was measured with a colorimetric color difference meter (ZE6000; manufactured by Nippon Denshoku Industries Co., Ltd.).

  From the evaluation results of Table 2, the epoxy resin having a specific polyglycerin structure of the present invention has high heat resistance, and the epoxy resin composition containing the compound has a high curing speed. When cured using the epoxy resin composition, It was found that a cured product with small color after curing and excellent flexibility was obtained.

  The epoxy resin having a specific polyglycerin structure of the present invention has high heat resistance, and the epoxy resin composition containing the compound has a high curing speed, and when cured using it, the color after curing is small and flexible. A cured product having excellent properties can be obtained. Therefore, it can be applied to various fields such as coating agents, adhesives, electrical / electronic components, sealing agents, optical materials, and the like, and its industrial utility value is extremely high.

Claims (5)

  An epoxy resin obtained by a reaction of polyglycerin and epihalohydrin, wherein the total of triglycerin concentration and tetraglycerin concentration is 60% by weight or more.   2. The epoxy resin according to claim 1, wherein the concentration of each of triglycerin and tetraglycerin constituting polyglycerin is in the range of 10% by weight to 70% by weight.   The epoxy resin according to claim 1 or 2, wherein the concentration of diglycerin constituting the polyglycerin is less than 10% by weight.   An epoxy resin composition comprising the epoxy resin according to claim 1 and a curing agent.   The epoxy resin composition according to claim 4, wherein the curing agent is a cationic polymerization initiator.