JP2001316451A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems of conventional one-pack thermosetting epoxy resin compositions such as a high curing temperature and a long curing time when a latent curing agent is employed, difficulty in obtaining a microcapsule excellent in rupture characteristics, necessity of homogeneous pressurization for a pressure-rupture type microcapsure, unsharpness of temperature sensitivity characteristics for a temperature-rupture type microcapsule when a microcapsulated curing agent is employed, and the like. SOLUTION: The low-temperature fast curable epoxy resin composition which can be compounded into one-pack composition comprises an epoxy resin and, incorporated therewith, a thiopropionate and/or a thioglycolate as a curing agent, a tertiary amine adduct-based latent curing accelerator as a curing accelerator and a borate and a phenolic resin as preservation stabilizers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting epoxy resin composition which can be applied to various electronic parts and industrial equipment at a low temperature and has a rapid curing property and can be formed into one liquid.

[0002]

2. Description of the Related Art Conventionally, epoxy resins have been widely used as coating agents, adhesives, casting agents, etc. due to their excellent cured physical properties. Conventional epoxy resin composition,
A so-called two-pack type in which two components consisting of a main agent and a curing agent are mixed at the time of use is often used. The two-pack type epoxy resin composition can be a composition that can be cured even near room temperature by a combination of an epoxy resin as a main component and a curing agent, or can be cured by heating and can control the curing temperature and time, Since the main agent and the curing agent are separated from each other, they have advantages such as good storage stability (shelf life). On the other hand, precise work such as measurement and mixing of the main agent and the curing agent is necessary, and generally the work time (pot life) of the mixture of the main agent and the curing agent is short, so the operation must be performed promptly, There are disadvantages such as the workability changes due to the increase in viscosity over time, and in some cases, it becomes gelled and unusable.

[0003] Therefore, a one-pack type thermosetting epoxy resin composition in which a curing agent and an epoxy resin which do not have these disadvantages are mixed in advance has been developed. For example, a latent curing agent such as dicyandiamide, melamine, or imidazole as a curing agent, or a highly reactive curing agent contained in microcapsules that are physically destroyed by pressure, heat, etc. are used. ing.

[0004]

However, when a latent curing agent is used in the conventional one-pack type thermosetting epoxy resin composition, there is a disadvantage that the curing temperature is high and the curing time is long. Also, when using a microencapsulated hardener, it is difficult to obtain a microcapsule having excellent destruction characteristics. There were problems such as the characteristics being not sharp.

The present invention has been made to solve the above-mentioned problems of the prior art, and is intended to be performed at a temperature of 100.degree.
Provide a low-temperature fast-curing one-pack type thermosetting epoxy resin composition that cures at a temperature of 0 to 80 ° C. for several seconds to several minutes and has a storage stability of one month at room temperature or one week or more at 40 ° C. The purpose is to:

[0006]

Means for Solving the Problems The present inventors have found that the problem can be solved by combining a specific curing agent, a curing accelerator and a storage stabilizer with a specific epoxy resin, and complete the present invention. Reached. The specific epoxy resin used in the present invention is one or two or more liquid epoxy resins selected from bisphenol F diglycidyl ether, bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, and glycidylamine. . As liquid epoxy resins, propylene glycol diglycidyl ether, cyclohexyl diglycidyl ether, hydrogenated dicyclopentadiene diglycidyl ether, and the like are also commercially available, but these gel to a short time after mixing or have extremely poor storage stability. It is not preferable to apply to the present invention.

[0007] Specific curing agents used in the present invention include liquid polymercaptans such as thiopropionate (mercaptopropionate) and thioglycolate (mercaptoglycolate).
As polymercaptans having SH (thiol) groups, there are liquid polymercaptans and polysulfide resins, and when used as a curing agent for epoxy resins, these alone do not have a very high curing speed, but use a Lewis base as a promoter. Then, low-temperature curing is possible even at 0 to -20 ° C. At room temperature, the pot life is only about 2 to 10 minutes, but it shows a fast curing property that a practical cured state can be obtained in 10 to 30 minutes. Etc. are known.
In the present invention, not all polymercaptans can be used, and a polymercaptan having a specific structure is preferred. These are thiopropionic acid (mercaptopropionic acid) or thioglycolic acid (mercaptoglycolic acid) and bifunctional alcohol butanediol, trifunctional trimethylolpropane, tris- (2-hydroxyethyl) isocyanurate or tetrafunctional pentane. It is an esterified product with a polyhydric alcohol such as erythritol. These may be used alone or as a mixture. still,
Generally, the more polyfunctional, the better the curability, and the lower the functional, the lower the viscosity.
The functional one is used alone, and the bifunctional one is used by blending it with the trifunctional one. In addition to the above, as a substance having an SH (thiol) group, there are a compound obtained by reacting H ₂ S at both terminals of a bisphenol A epoxy resin and thiochol which is a polysulfide. It is not preferred because it is gelled or has extremely poor storage stability or has a very slow curing reaction. In the present invention, for 100 parts by weight of a specific epoxy resin,
The amount of the specific curing agent to be added can be determined stoichiometrically based on the epoxy equivalent of the epoxy resin and the mercaptan equivalent of the curing agent. The value can be adopted, generally in the range of 30 to 100 parts by weight of the reactivity,
It is preferable from the viewpoint of physical properties.

As the specific curing accelerator used in the present invention, a tertiary amine adduct type latent curing accelerator is preferable.
These use tertiary amines as adducts with epoxy resins, phenolic resins, isocyanate compounds and the like. These are latent curing agents for epoxy resins,
Alternatively, it is widely used as a curing accelerator for curing an epoxy resin with an acid anhydride curing agent, but has not been known as a curing accelerator for an epoxy resin and a polymercaptan curing agent. Commercially available products that can be used as the curing accelerator of the present invention include Ajinomoto Ajicure MY series, Asahi Denka Adeka Hardener EH-3849S,
EH-3670S, NOVACURE HX-374 manufactured by Asahi Kasei Corporation
1, HX-3742, HX-3748, HX-3088
and so on. These may be used alone or as a mixture. In the present invention, with respect to 100 parts by weight of the specific epoxy resin, the amount of the specific curing accelerator is different depending on the type of the curing accelerator used, but it is generally preferable to mix in the range of 5 to 50 parts by weight, It is preferable from the viewpoint of physical properties. In particular, if the amount is less than this, the storage stability becomes better, but the curing speed becomes slower.If the amount is more than this, the low-temperature fast curing becomes remarkable, but the storage stability decreases, so that more storage stability is obtained. Addition of an agent is required, which is not preferable.

As the specific storage stabilizer used in the present invention, an alkyl or aryl ester of boric acid is used alone or in combination with a phenol resin. The borate ester is an alkyl or aryl ester of boric acid, specifically, trimethyl borate, triethyl borate, tributyl borate, triphenyl borate and the like. These are available as reagents. In the present invention, it is preferable from the viewpoint of reactivity and physical properties that the amount of the boric acid ester is in the range of 0.1 to 3.0 parts by weight based on 100 parts by weight of the specific epoxy resin. In particular, if the compounding amount is less than this, the storage stability improving effect is not obtained, and if it exceeds this amount, the curing reactivity is extremely reduced,
Conversely, storage stability may be deteriorated, which is not preferable. The addition of a borate ester as a storage stabilizer to a system in which an epoxy resin is blended with an adduct-based curing agent or a curing accelerator is known as JP-A-06-172495. There was no indication that these were effective.

Japanese Patent Application Laid-Open No. 06-172495 discloses that a boric acid or borate compound and a phenol compound are allowed to coexist as a preservation stabilizer. it can. When coexisting, all phenolic compounds described in JP-A-06-172495 are not effective, and phenol resins are particularly preferred in the present invention.
An example is a Reptop PS29 manufactured by Gunei Chemical Industry Co., Ltd.
Phenolic resin such as 80, SN-1 manufactured by Nippon Steel Chemical Co., Ltd.
Resins having an aralkyl structure based on β-naphthol such as No. 70 or Nikanol HP- manufactured by Mitsubishi Gas Chemical Company, Inc.
An alkylphenol-modified xylene resin such as 100 can be used. These are all resins having a structure in which a hydroxyl group is directly attached to an aromatic ring, and are generally referred to as phenolic resins in the present invention. Among phenolic compounds, hydroquinone, methoquinone, methylhydroquinone, resorcinol, tertiary butyl phenol and the like are not preferred because they do not have the effect of improving storage stability. When a phenol resin is allowed to coexist, the amount thereof is preferably 3.0 parts by weight or less based on 100 parts by weight of the specific epoxy resin from the viewpoint of reactivity and physical properties. In particular, if the amount is more than this, the storage stability decreases, which is not preferable.

In order to make the thermosetting epoxy resin composition of the present invention comprising an epoxy resin, a curing agent, a curing accelerator and a storage stabilizer into one liquid, the order of addition of each component is very important. . Generally, (1) a method in which a storage stabilizer is uniformly dissolved in an epoxy resin, a curing agent is added and uniformly mixed, and finally, a curing accelerator is added. (2) A curing agent is added to the epoxy resin. After adding and mixing uniformly, a storage stabilizer is uniformly dissolved in this, and finally a curing accelerator is added,
(3) Epoxy resin with hardener uniformly dissolved (A
Solution), a solution in which a curing accelerator is uniformly dissolved in an epoxy resin (solution B), and a solution in which a storage stabilizer is uniformly dissolved in an epoxy resin (solution C). (4) a mixture of an epoxy resin and a curing accelerator (solution D) and a mixture of a curing agent and a storage stabilizer (solution E). A one-pack type thermosetting epoxy resin composition having excellent storage stability is prepared by adding or the like.

However, for example, in a method of mixing a curing agent and a curing accelerator in an epoxy resin and finally adding a storage stabilizer, sometimes the curing agent and the curing accelerator are rapidly mixed in the epoxy resin at the time of mixing. It is not preferable because excessive thickening and gelation occur. It is needless to say that the thermosetting epoxy resin composition of the present invention can be separated into two or three liquids and stored, and can be mixed and used at the time of use. In that case,
It is necessary to store the above solution A, solution B, and solution C as three solutions, mix solution A and solution C, and then add solution B. In addition, a liquid mixture of liquid A and liquid C is prepared and stored in advance,
It is also possible to use two liquids in which liquid B is added at the time of use, or two liquids of liquid D and liquid E.

The epoxy resin composition of the present invention may contain calcium carbonate, talc, barium sulfate, silica,
Alumina, metal powder, glass, inorganic fillers such as ceramics or silicone resin, phenolic resin, melamine resin, benzoguanamine resin, urethane resin, organic fillers such as polyolefin resin, thixotropic agent such as Aerosil and organic bentonite, Adhesion imparting agents such as silane-based, aluminum-based or titanium-based coupling agents, nonionic surfactants for silicone oil or acrylic resin-based defoamers, dispersants, and antistatic agents, for coloring May be appropriately blended.

[0014]

According to the present invention, it is possible to achieve a low-temperature rapid curing property which cannot be achieved by the conventional one-pack type epoxy resin composition which has heretofore generally been composed mainly of dicyandiamide. Specifically, 100 ° C or less, preferably 70 to 80 ° C
Curing is possible at a temperature of several seconds to several minutes. In addition, the storage stability is not less than 1 month at room temperature or 1 year at 40 ° C.
A one-pack type epoxy resin composition having storage stability of not less than one week and significantly improved workability can be obtained.

[0015]

The present invention will be described in more detail with reference to the following examples. Examples 1 to 8 Epoxy resin Epicoat 807 (bisphenol F type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.) was added with TPB (triphenyl borate ester) as a storage stabilizer and resin top PS2980 of phenol resin (Gunei Chemical Industry Co., Ltd.) Made)
And mixed uniformly with three rolls. The curing agent Cup Cure QX-40 (polymercaptan curing agent,
Pentaerythritol tristhiopropionate, presumably made by Yuka Shell Epoxy), BDTP
(Butanediol bisthiopropionate), T
MTP (trimethylolpropane tristhiopropionate), PETP (pentaerythritol tetrakisthiopropionate), THEIC-BMP
A (tris- (2-hydroxyethyl) isocyanurate tristhiopropionate), TMTG (trimethylolpropane tristhioglycolate)
Was added in a predetermined amount as shown in the formulation of Table 1, followed by uniform mixing. Finally, Acucur MY-H (tertiary amine adduct type latent curing accelerator, manufactured by Ajinomoto Fine Techno Co.) as a curing accelerator and fine powder silica (Aerosil #) as a thixotropic agent
200) and stirred well to form a uniform epoxy resin composition. The composition is shown in Table 1. For these epoxy resin compositions, a gelation tester GT-D-JI
The gelation time at 100 ° C. and 80 ° C. was measured using S (Nissin Kagaku). The initial viscosity at 25 ° C. was measured with a Brookfield EHD viscometer (3 degree cone).
In addition, these are stored in a constant temperature room at 25 ° C and 40 ° C,
Take it out at any time, measure its viscosity at 25 ° C,
The storage stability was evaluated in comparison with the initial viscosity. Table 1 shows the results
It was shown to.

[0016]

[Table 1]

Polymercaptan curing agents studied in Table 1
In addition, Epo available from Yuka Shell Epoxy
Mate QX-10, Epomate QX-11, Epomate
QX-20, Cup Cure WR-6, Cup Cure 38
00 and Toray Thiokol LP-3
The same evaluation was carried out for
The compound does not cure even at 150 ° C for 600 seconds.
It hardens with rapid heat generation within hours
Could not be used. Of these, Epomate QX-1
0, Epomate QX-20, Cup Cure WR-6
Is the above result because the curing accelerator has already been added.
It is estimated that In addition, a curing accelerator is compounded.
Uncured Cup Cure 3800, Epomate QX-1
1. Due to its chemical structure, Thiokol LP-3 is
It is presumed that it cannot be used for In addition, Cup Cure 3
800 is R- [O (C₃H₆O) _nCH₂CH (O
H) CH₂SH]_m, Epomate QX-11 is HS-
CH₂CH (OH) O-Ph-C (CH₃)₂-Ph-
O-CH (OH) CH₂SH (Ph is a phenyl group),
Ochol LP-3 is HS- (C₂H₄OCH₂OC₂H
₄-SS)_n-C₂H₄OCH₂OC₂H₄-SH and
Presumed. From the above results, it was found that epoxy
Thiopropionic acid ester and / or
Or thioglycolic acid ester, tertiary as a curing accelerator
Amine adduct latent curing accelerator, storage stabilizer
Combining borate ester and phenolic resin
Has excellent curability and good storage stability
Is.

Comparative Examples 1 to 8 Epoxy resin Epicoat 806L (bisphenol F type epoxy resin, manufactured by Yuka Shell Epoxy Co.) was added with a hardening agent Adeka Hardener EH317 (polymercaptan type hardening agent, pentaerythritol tristhiopropionate). (Asahi Denka Co., Ltd.) alone to obtain an epoxy resin composition (Comparative Example 1). The gelation time was measured in the same manner as in Example 1. As a result, the gelation did not occur at 100 ° C. for 5 minutes, but the storage stability was good and the fluidity was exhibited even after 30 days at room temperature. Table 2 summarizes the results of attempting to add various curing accelerators to Comparative Example 1. DMP-30 commercially available as an epoxy resin curing accelerator as a curing accelerator
(2- (dimethylaminomethyl) phenol), EpiCure D (DMP-30 tris-2-ethylhexanoate, manufactured by Yuka Shell Epoxy), DBU (1,8-diazabicycloundecene, manufactured by San Apro) , SA102
(DBU octylate, manufactured by San Apro), SA810
(DBU orthophthalate, manufactured by San Apro) was used. As is clear from the results shown in Table 2, remarkable curing acceleration was achieved by adding a curing accelerator to the composition of Comparative Example 1, but the storage stability at room temperature was extremely reduced.

[0019]

[Table 2]

Examples 9-12, Comparative Examples 9-12 Epoxy resin epicoat 806L or epicoat 82
8 (bisphenol A type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.), a hardening agent ADEKA HARDNER EH317, and a storage stabilizer TBB (tributyl borate ester) and P
The epoxy resin composition of Table 3 was prepared in the same manner as in Example 1 by changing the type of the curing accelerator in the epoxy resin composition obtained by combining S2980, and the gelation time and the time until gelation at room temperature were measured. The results are shown in Table 3. As the curing accelerators, tertiary amine adduct-type latent curing accelerators, Ajicure MY-H and MY-D (all manufactured by Ajinomoto Fine-Techno Co., Ltd.), Adeka Hardener EH3670S
(Asahi Denka Co., Ltd.) has good curability and storage stability. On the other hand, Aicure PN-H containing a secondary amine even with a latent curing accelerator has insufficient storage stability at 40 ° C.
DICY (dicyandiamide), Curesol 2MA-
It is clear that OK (2,4-diamino-6 [2'-methylimidazolyl- (1) '] ethyl-s-triazine / isocyanuric acid adduct) has poor curability.

[0021]

[Table 3]

Examples 13 to 15, Comparative Examples 13 to 16 Epoxy resin epicoat 807, curing agent cup cure Q
X-40, a curing accelerator AMICURE MY-H, an epoxy resin composition of Table 4 in which TBB and various phenols were combined as a storage stabilizer were prepared in the same manner as in Example 1, and the gelation time, 25 ° C. and 40 ° C. The viscosity at ° C was measured. The results are shown in Table 4, and among the phenols examined, SN-170
(A resin having an aralkyl structure based on β-naphthol, manufactured by Nippon Steel Chemical Co., Ltd.) or Nicanol HP-100
Only when a phenol resin such as (alkylphenol-modified xylene resin, manufactured by Mitsubishi Gas Chemical Company) was used, good curability and storage stability were exhibited. However, it was found that when hydroquinone, methoquinone, pyrogallol, and p-tert-butylphenol were used, the storage stability at 40 ° C was extremely poor.

[0023]

[Table 4]

Examples 16-18, Comparative Examples 17-19 Epoxy resin epicoat 807, curing agent cup cure Q
X-40, constant with the curing accelerator AMICURE MY-H,
TBB and resin top PS2980 as storage stabilizer
In order to investigate the effect of the amount of the epoxy resin, an epoxy resin composition shown in Table 5 was prepared in the same manner as in Example 1, and the gelation time and the viscosities at 25 ° C. and 40 ° C. were measured. The results are shown in Table 5, and it is clear that the curability and the storage stability vary greatly depending on the amount of the storage stabilizer.

[0025]

[Table 5]

Examples 19 to 23 Epoxy resin epicoat 807, curing agent cup cure Q
X-40, constant with the curing accelerator AMICURE MY-H,
TPB as storage stabilizer and resin top PS2980
In order to examine the effect of the amount of the epoxy resin, an epoxy resin composition shown in Table 6 was prepared in the same manner as in Example 1, and the gelation time and the viscosities at 25 ° C. and 40 ° C. were measured. The results are shown in Table 6, and these compositions had a good balance between curability and storage stability. .

[0027]

[Table 6]

Example 24 100 g of Epicoat 807 as an epoxy resin, 1 g of TPB as a storage stabilizer, and a resin top PS298
0 and 0.5 g were mixed and roll-dispersed. To 10.15 g of this resin solution, 6 g of TMTP as a curing agent was added and mixed well, then 2 g of Amicure MY-H was added and mixed as a curing accelerator, and the mixture was further degassed by vacuum stirring to remove the foam of the present invention. An epoxy resin composition was prepared. To 10 g of this epoxy resin composition, 40 g of spherical silver powder having an average particle size of 9 μm and 15 g of flaky silver powder were mixed by a self-rotating stirrer to form a silver paste. This conductive adhesive was printed on a printed circuit board in place of the conventional cream solder, and after mounting a chip resistor (size 2125), it was heat-treated at 80 ° C. for 30 minutes and fixed. Connection resistance of chip resistor is 25m on average
In Ω, the adhesive strength was 3 kg or more, and this conductive adhesive could be used as a substitute for solder joining.

[0029]

According to the present invention, it is possible to achieve a low-temperature and fast-curing property which cannot be achieved by the conventional one-pack type epoxy resin composition which has generally been constituted mainly of dicyandiamide. Specifically, 100 ° C. or lower, preferably 70 to 8
Curing becomes possible at a temperature of 0 ° C. in a few seconds to a few minutes. In addition, regarding storage stability, at room temperature for 1 month or more, or at 40 ° C.
Thus, a one-pack type epoxy resin composition having storage stability of one week or more and significantly improved workability can be obtained.

Claims (5)

[Claims] 1. An epoxy resin comprising a thiopropionate and / or thioglycolate as a curing agent, a tertiary amine adduct-based latent curing accelerator as a curing accelerator, a boric acid ester and a phenolic resin as a storage stabilizer. A thermosetting epoxy resin composition comprising: 2. The epoxy resin according to claim 1, wherein the epoxy resin is bisphenol.
2. The thermosetting composition according to claim 1, wherein one or more liquid epoxy resins selected from F-diglycidyl ether, bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether and glycidylamine are used. Epoxy resin composition. 3. The epoxy resin curing agent according to claim 1, wherein the epoxy resin curing agent is an ester of thiopropionic acid or thioglycolic acid with a polyhydric alcohol such as butanediol, trimethylolpropane, pentaerythritol, and tris- (2-hydroxyethyl) isocyanurate. A thermosetting exci resin composition characterized by being a compound. 4. A thermosetting epoxy resin composition according to claim 1, wherein the curing accelerator is a latent curing accelerator which is an adduct of a tertiary amine and an epoxy resin, a phenol resin, an isocyanate compound or the like. . 5. A thermosetting epoxy resin composition according to claim 1, wherein the storage stabilizer is an alkyl or aryl ester of boric acid alone or in combination with a phenol resin.