JP2000169552A - Cationically curable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cationically curable resin composition which is a cationically curable epoxy resin composition excellent in workability at a low viscosity, and simultaneously excellent in the water resistance and flexibility of cured products compared to those of the conventional epoxy resin cured products. SOLUTION: A cationically curable resin composition comprises 5-95 wt.% epoxy resin and 95-5 wt.% oxetane, and as one component of the epoxy resin, 1-90 wt.%, based on the total amount of the epoxy resin, polyfunctional epoxy compound obtained by reacting a polyether polyol represented by the formula: HO-(XO)m-ZO-(YO)n-OH (wherein Z is a dimer diol residue; X and Y are the same or different 2-4C alkylene groups; and m and n are the same or different integers of 0 or more and, at the same time, 2<=m+n<=40) with epichlorohydrin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cationically curable epoxy resin composition having low viscosity, excellent workability, and excellent curability and low shrinkage. The cured product of the composition of the present invention has excellent water resistance, heat resistance and flexibility as compared with the conventional epoxy resin cured product, and has a coating material, a film / sheet-like material, a molding material, a sealing material and an adhesive. It is suitable for use as an agent.

[0002]

2. Description of the Related Art In the field of active energy ray-curable resins which are cured by ultraviolet rays or electron beams, recently cation-curable oxetane compounds, that is, oxetane rings (four-membered rings comprising three carbon atoms and one oxygen atom) Cyclic ether)
(Hereinafter, a group of compounds belonging to this group will be simply referred to as oxetane). Oxetane is less susceptible to oxygen inhibition and excellent in thin film curability than polyfunctional acrylate, and also has properties such as toughness of the cured product and low skin irritation. Furthermore, since it is excellent in copolymerizability with a general-purpose epoxy resin, a cured product having good mechanical strength and adhesiveness can be easily obtained by using it in combination with oxetane (for example, JP-A-8-85775). And JP-A-8-134405).

[0003] However, cured products obtained from oxetane and general-purpose epoxy resins have high elastic modulus and high strength, but are poor in flexibility and brittle, so that they are difficult to use in applications requiring flexibility such as films. there were. Hitherto, as a technical means for improving the water resistance, heat resistance and flexibility of an epoxy resin, it has been known to add diglycidyl ether of dimer diol (JP-A-2-25578, JP-A-3-275711). No.). However,
Since diglycidyl ether of dimer diol is excessively hydrophobic, it has poor compatibility with an epoxy resin having hydrogenated bisphenol A as a skeleton, and has a problem that separation is likely to occur at the time of compounding or curing.

An object of the present invention is to improve the water resistance, heat resistance and flexibility of a cured product of a resin composition comprising an epoxy resin and oxetane without causing the above-mentioned problems. did.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, converted the hydroxyl groups of polyether polyol obtained by adding alkylene oxide to dimer diol to glycidyl groups. The present inventors have found that the compound has excellent compatibility with other epoxy resins, and that a cured mixture thereof is excellent in water resistance, heat resistance and flexibility, thereby completing the present invention. That is, the present invention relates to a cationically curable resin composition comprising 5 to 95% by weight of an epoxy resin and 95 to 5% by weight of oxetane, wherein a polyether represented by the following chemical formula (1) is included as one component of the epoxy resin. A cationically curable resin composition containing a polyfunctional epoxy compound obtained by reacting a polyol with epichlorohydrin in an amount of 1 to 90% by weight based on the total amount of the epoxy resin. Chemical formula: HO- (XO) _m- ZO- (YO) _n- OH (1) (wherein, Z is a dimer diol residue, X and Y are the same or different alkylene groups having 2 to 4 carbon atoms, and m
And n are the same or different integers each being 0 or more, and 2 ≦ m + n ≦ 40. Hereinafter, the present invention will be described in more detail.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin in the present invention comprises:
It is composed of the polyfunctional epoxy compound (hereinafter referred to as polyether-modified epoxy compound) and another epoxy resin, and the ratio of the polyether-modified epoxy compound is 1 to 90 based on the total amount of all the epoxy compounds constituting the same. % By weight. A more preferable ratio of the polyether-modified epoxy compound is 5 to 60% by weight.
When the proportion of the polyether-modified epoxy compound is less than 1% by weight, the flexibility and water resistance of the cured product are poor, while
If it exceeds 0% by weight, the mechanical strength of the cured product will decrease.

As described above, the polyether-modified epoxy compound is a polyether polyol represented by the following chemical formula (1) (hereinafter simply referred to as polyether polyol).
And epichlorohydrin. In the chemical formula (1), HO- (XO) _m -ZO- (YO) _n -OH, X and Y are the same or different alkylene groups having 2 to 4 carbon atoms, and specifically, an ethylene group, Examples thereof include a methylethylene group, an n-propylene group, and an n-butylene group. Preferred is an ethylene group in terms of easy reaction with epichlorohydrin and excellent compatibility with other epoxy resins described below. Further, m and n are the same or different integers of 0 or more, and 2 ≦ m + n ≦ 40. When m + n is less than 2, the compatibility with other epoxy resins is poor, while when m + n is more than 40, the water resistance and flexibility due to the dimer diol residue are poor. Polyether polyols are those in which oxyalkylene groups are added to both ends of the dimer diol (ie, m and
Even when n is an integer of 1 or more, the dimer diol has an oxyalkylene group added to only one end (that is, one of m and n is 0).
And the other is an integer of 2 or more). Preferably, an oxyalkylene group is added to both ends of the dimer diol.

[0008] The method for synthesizing the polyether polyol is not particularly limited. For example, it can be produced by adding an alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide or tetrahydrofuran to a dimer diol. Such an addition reaction is described in, for example, “Experimental Method for Polymer Synthesis”, Nos.
This is described in detail in the description of the ring-opening polymerization method of an oxygen-containing cyclic compound on page 1979 (published by Kagaku Dojinsha). The dimer diol is sold, for example, by Toagosei Co., Ltd. as "Pespol HP-1000".

By subjecting the above polyether polyol and epichlorohydrin to a desalting reaction, the polyether-modified epoxy compound of the present invention can be obtained. The above reaction is carried out in the presence of a strong base such as sodium hydroxide at 40 to 80.
C. for 1 to several hours. A reaction solvent may or may not be used, and when used, for example, ethyl acetate, toluene or xylene is preferable. The reaction ratio between the polyether polyol and epichlorohydrin is preferably from 1.2 to 2.5 mol of epichlorohydrin to 1 mol of the polyether polyol. When the amount is less than 1.2 mol, the epoxy purity at the terminal becomes low, and the water resistance or strength when cured is likely to decrease. On the other hand, when the amount exceeds 2.5 mol, the reaction rate is not changed as compared with the case where the amount is less than 2.5 mol, and only a large amount of excess epichlorohydrin remains.
The amount of the base added was 1 mol of epichlorohydrin,
0.8-1.2 mol is preferred. The strong base may be added to the reaction system as a solid, or may be added as an aqueous solution. Further, in order to accelerate the reaction, a phase transfer catalyst such as tetrabutylammonium bromide or tetrabutylammonium chloride may be added. The addition amount is preferably 0.1 to 5 parts by weight based on the total amount of the reaction solution. The epoxy equivalent of the polyether-modified epoxy compound obtained by the above synthesis method is 1000 g /
eq or less. If it exceeds 1000 g / eq, the strength of the cured product tends to decrease. More preferably,
It is 700 g / eq or less.

As the other epoxy resin used together with the polyether-modified epoxy compound, bisphenol A glycidyl ether type epoxy resin, a novolak resin modified with epichlorohydrin, a cresol novolak resin modified with epichlorohydrin, and the like are preferable.
The preferred epoxy equivalent of these epoxy resins is 700
g / eq or less, more preferably 500 g / eq.
It is as follows. By using an epoxy resin having such an epoxy equivalent, a cured product having excellent heat resistance can be obtained.

As the oxetane, any oxetane having at least one oxetane ring in the molecule can be used.
Specifically, JP-A-8-85775 and JP-A-8-1
Various oxetane compounds described in No. 34405 are exemplified. Those having one or two oxetane rings in one molecule are preferable in that they are suitable for lowering the viscosity of the curable composition. A typical monofunctional oxetane is 3-ethyl represented by the following formula (1). 3-[(phenoxy) methyl] oxetane, 3-ethyl-3- represented by the following formula
(Hexyloxymethyl) oxetane, 3-ethyl-3-
(Hydroxymethyl) oxetane and the like, and typical bifunctional oxetanes include 1,4-bis [(3
-Ethyl-3-oxetanylmethoxy) methyl] benzene, bis {[1-ethyl (3-oxetanyl)] methyl} ether and the like.

[0012]

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[0013]

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The cationically curable resin composition comprising the epoxy resin and oxetane is cured by cationic polymerization. In summary, the cationic polymerization initiator used together generates a cation upon irradiation with light, and the cation is added to an oxygen atom forming an epoxy ring and / or an oxetane ring to form an oxo group. A cation is generated, and this is a starting point of the growth reaction, and the polymerization proceeds. Examples of the cationic polymerization initiator include diaryliodonium salts and triarylsulfonium salts. In addition, for example, “UV / EB curable materials” issued by CMC Co., Ltd. (1992) 63-6.
The compounds described on page 5 can also be used.

The preferred amount of the cationic polymerization initiator used is
0.2 to 10 parts by weight, more preferably 0.2 to 10 parts by weight, per 100 parts by weight of the total amount of the epoxy resin and oxetane.
5 to 5 parts by weight. Further, a filler such as calcium carbonate, alumina, silica or quartz powder, a coupling agent, a flame retardant, and the like may be added to the cationically curable resin composition of the present invention. Hereinafter, the present invention will be described more specifically with reference to specific examples.

Synthesis Example 1 (Synthesis of polyether polyol) In a nitrogen-purged autoclave, 100 g (0.187 mol) of dimer diol ["Pespol HP-1000" manufactured by Toagosei Co., Ltd., hydroxyl value: 197 mgKOH / g] And 52.4 g of a 40% aqueous solution of potassium hydroxide
(0.374 mol) at a temperature of 100 ° C. and a pressure of 5
A reaction product having a water content of about 100 ppm was obtained by performing a dehydration reaction at mmHg for 3 hours. This reaction solution (114.2)
g) is heated to 110 to 120 ° C., and 5 kg /
ethylene oxide 4 over 4 hours under a pressure of ² cm ²
9.4 g (1.12 mol) was gradually added and reacted.
The reaction product obtained is cooled to 60 ° C. and then 10 mm
Unreacted ethylene oxide was removed under reduced pressure of Hg.
After neutralizing the reaction product with hydrochloric acid, dehydration and filtration were performed, and a polyether polyol obtained by adding ethylene oxide to dimer diol (having a hydroxyl value of 140.8 mg KOH)
/ G, number average molecular weight 800; hereinafter, abbreviated as DDE) is 1
43 g were obtained. As a result of ¹ H-NMR measurement, DDE was found to be a diol to which 6.0 mol of ethylene oxide was added per 1 mol of the dimer diol.

Synthesis Example 2 (Synthesis of polyether-modified epoxy compound) DDE (100 g), epichlorohydrin (25 g),
Place sodium hydroxide (11 g) and tetrabutylammonium bromide (1 g) in a flask and at 80 ° C.
After stirring for 4 hours, the mixture was cooled to room temperature and washed twice with 60 parts of water. After filtering this reaction solution, distillation was performed at 60 ° C. under reduced pressure to remove excess epichlorohydrin, thereby obtaining DDE diglycidyl ether (hereinafter referred to as DDE).
G) (102 g). When the epoxy equivalent of the obtained DDEG was measured according to the method of JIS K7236, it was 508 g / eq.

Synthesis Example 3 (Synthesis of dimer diol / epoxidized product) Dimer diol (100 g), epichlorohydrin (30 g), sodium hydroxide (16 g) and tetrabutylammonium bromide (1 g) were placed in a flask, and placed at 80 ° C. Stirred for hours. Then, after cooling to room temperature,
Washing was performed twice with 60 parts of water. After filtering this reaction solution, excess epichlorohydrin was removed by distillation under reduced pressure,
Diglycidyl ether of dimer diol (hereinafter DDG)
104 g). The epoxy equivalent of this DDG was 469 g / eq.

[0019]

EXAMPLES AND COMPARATIVE EXAMPLES A cured composition containing each component at a ratio shown in Table 1 was poured into a mold (14 cm × 4 cm, thickness of about 0.5 mm) placed on a propylene film. After being covered with a propylene film, the film was cured by irradiating ultraviolet rays under the following conditions. That is, a conveyor type ultraviolet irradiation apparatus having a lamp of 120 W / cm (lamp height: 1
0 cm, conveyor speed; 10 m / min, irradiation intensity: 78
(0 W / cm ² ) and cured by irradiating it three times repeatedly. After leaving the cured film at room temperature for one day, the propylene film was peeled off and the width was 1.5 cm and the length was 14 cm.
cm, and a tensile test (tensile speed: 200 mm / mi
n, distance between marked lines; 100 mm). At the same time, film warpage (visual observation) and bendability (evaluated by breaking or not when the film is bent at 180 °)
Were also evaluated, and the results are shown in Table 1.

[0020]

[Table 1]

The meanings of the abbreviations used in Table 1 are as follows. POX: 3-ethyl-3-[(phenoxy) methyl] oxetane XDO: 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene YD128: bisphenol A epoxy resin CD1011 manufactured by Toto Kasei Co., Ltd. : Triarylsulfonium hexafluorophosphate manufactured by Satmer

As is evident from Table 1, the general-purpose epoxy resin / oxetane composition provides only a brittle and inextensible film. Further, diglycidyl ether (DDG) of dimer diol has poor compatibility and a uniform liquid cannot be obtained. On the other hand, according to the composition of the example to which the polyether-modified epoxy compound of the present invention was added, the composition was transparent,
A flexible and tough film is obtained.

[0023]

The cationically curable composition of the present invention has excellent curability and the cured product has excellent flexibility, transparency and water resistance. In view of having such properties, the cationically curable composition is suitably used for materials for optical films and sheets, coating agents, molding materials, adhesives, and electric insulating materials.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4H017 AA04 AB08 AB17 AC17 AD06 4J036 AB01 AB02 AB03 CA28 DC14 HA03 JA06 JA07 JA08 4J038 DB031 JA69 MA15 NA04 NA12 NA14 NA23 4J040 EC001 EC002 EC021 EC022 EC251 EC252 GA08 HB43 LA01 LA06 LA08 LA08

Claims (1)

[Claims] 1. A cationically curable resin composition comprising 5 to 95% by weight of an epoxy resin and 95 to 5% by weight of oxetane, wherein a polyether polyol represented by the following chemical formula (1) is included as one component of the epoxy resin. And a polyfunctional epoxy compound obtained by reacting epichlorohydrin with
A cationically curable resin composition containing 1 to 90% by weight based on the total amount of the epoxy resin. Chemical formula: HO- (XO) _m- ZO- (YO) _n- OH (1) (wherein, Z is a dimer diol residue, X and Y are the same or different alkylene groups having 2 to 4 carbon atoms, and m
And n are the same or different integers each being 0 or more, and 2 ≦ m + n ≦ 40. )