JPH04351653A - Epoxy resin composition and its cured product - Google Patents

Abstract

PURPOSE:To provide an epoxy resin composition which can be desirably used as a liquid crystal sealing material and excels in dimensional accuracy when used as a sealing material, can prevent bleeding and void formation as much as possible and can produce a liquid crystal device of stable quality without fail. CONSTITUTION:An epoxy resin composition comprising an epoxy resin, a curing agent, a silicon-modified epoxy resin prepared by effecting an addition reaction of the alkenyl group of an alkenylated epoxy resin with the SSiH group of an organosilicon compound of the formula: HaRbSiO4-(a+b)/z (wherein R is a substituted or unsubstituted monovalent hydrocarbon or alkoxy group, a is a number of 0.01-1, b is a number of 1-3, the number of the silicon atoms in the molecule is an integer of 1-300, and the number of the hydrogen atoms directly bonded to the silicon atom in the molecule is an integer of 1 or greater), a gap filler comprising an inorganic or organic filler of a minor diameter of 3-10mum, and a fine silica powder of a mean particle size of 0.2-3mum.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention provides an epoxy resin composition that does not cause bleeding or elute components during curing, and can obtain accurate dimensional accuracy, and can therefore be suitably used as a liquid crystal sealing material. It relates to a product and its cured product.

0002

[Prior Art] Conventionally, epoxy resin or epoxy resin has been used as a sealing material for liquid crystal devices because it has superior moldability, adhesiveness, electrical properties, mechanical properties, moisture resistance, etc. compared to other thermosetting resins. It is common to use an epoxy resin composition containing an inorganic filler and the like.

0003

However, epoxy resins and epoxy resin compositions have problems such as bleeding during curing and insufficient dimensional accuracy due to thermal changes during curing. Therefore, in order to improve the dimensional stability, a method of mixing liquid rubber into the composition has been implemented, but this method has the problem of producing components that dissolve into the liquid crystal.

The present invention was developed in view of the above circumstances, and it is possible to obtain accurate dimensional accuracy without causing bleeding or elution components during curing, and is therefore suitable for use as a liquid crystal sealing material. An object of the present invention is to provide an epoxy resin composition and a cured product thereof.

[0005]

[Means and Effects for Solving the Problems] In order to achieve the above object, the present inventors have conducted intensive studies and found that an epoxy resin composition containing an epoxy resin and a curing agent has an alkenyl group-containing epoxy resin. The following formula (
A silicone-modified epoxy resin obtained by adding a ≡SiH group to an organosilicon compound represented by 1), and a short diameter of 3 to 10 μm.
By blending a gap agent consisting of an inorganic or organic filler with a fine powder of silica having an average particle size of 0.2 to 3 μm, the linear expansion coefficient of the composition can be lowered, the shape controllability can be improved, and the resin component can be reduced. It is possible to obtain an epoxy resin composition that achieves prevention of bleeding and has excellent performance as a liquid crystal sealing material; to c<e≦3/
The content of coarse particles having a particle size of e or more expressed by 5d is 0.
．． The present invention has been completed based on the discovery that it is preferable to adjust the content to 5% by weight or less, whereby the above-mentioned reduction in linear expansion coefficient, improvement in shape controllability, and prevention of bleed can be more effectively achieved.

[0006]

embedded image (However, in the formula, R represents a substituted or unsubstituted monovalent hydrocarbon group or an alkoxy group, a is a number from 0.01 to 1, and b is a number from 1 to 3. The number of silicon atoms in one molecule is
It is an integer of 1 to 400, and the number of hydrogen atoms directly bonded to silicon atoms in one molecule is an integer of 1 or more. )

0007
Therefore, the present invention provides (A) an epoxy resin, (B) a curing agent, and (C) an alkenyl group of the alkenyl group-containing epoxy resin containing an organosilicon compound represented by the above formula (1), ≡S.
A silicone-modified epoxy resin to which an iH group has been added, (D) a gap agent made of an inorganic or organic filler with a short diameter of 3 to 10 μm, and (E) an average particle size of 0.2 to 3 μm.
The present invention provides a liquid crystal sealing material characterized by containing fine powder silica, and a cured product thereof.

The present invention will be explained in more detail below. The liquid crystal sealing material of the present invention is mainly composed of an epoxy resin as a component (A) and a curing agent as a component (B). An epoxy resin composition containing component (B), (C) silicone-modified epoxy resin, and (D)
It is a mixture of a gap agent and (E) finely powdered silica.

The epoxy resin as the component (A) is as follows:
It has two or more epoxy groups in one molecule and will be described later (B
) There are no particular restrictions on the molecular structure, molecular weight, etc., as long as it can be cured with the curing agent of the component, and conventionally known epoxy resins can be used.

Specific examples of this epoxy resin include epoxy resins synthesized from epichlorohydrin and various novolac resins such as bisphenol, alicyclic epoxy resins, and epoxy resins into which halogen atoms such as chlorine and bromine atoms are introduced. be able to. Among these,
Glycidyl ether derivatives of bisphenol A or bisphenol F, which can provide a stable liquid composition at room temperature, are preferably used. In addition, these epoxy resins are 1
It is not limited to the types used, and two or more types can be used in combination.

The curing agent for component (B) includes those commonly used as curing agents for epoxy resins, such as amine curing agents such as diaminodiphenylmethane, diaminodiphenylsulfone, and metaphenylenediamine, phthalic anhydride, and pyromellitic anhydride. , acid anhydride curing agents such as benzophenone tetracarboxylic anhydride, and phenol novolac curing agents having two or more hydroxyl groups in one molecule such as phenol novolak and cresol novolak.

The epoxy resin composition of the present invention has the above-mentioned (A
) The main material is an epoxy resin composition containing an epoxy resin and the curing agent (B) above, but a monoepoxy compound and various curing accelerators are blended into this epoxy resin composition as necessary. be able to. Specific examples of monoepoxy compounds include styrene oxide, cyclohexene oxide, propylene oxide, methyl glycidyl ether, ethyl glycidyl ether, phenyl glycidyl ether, allyl glycidyl ether, octylene oxide, and dodecene oxide. Specific examples include imidazole or its derivatives, tertiary amine derivatives, phosphine derivatives, cycloamidine derivatives, and the like. In addition, the blending ratio of each component can be a normal blending ratio.

(C) added to this epoxy resin composition
As mentioned above, the component silicone-modified epoxy resin is one in which a ≡SiH group of an organosilicon compound represented by the following formula (1) is added to an alkenyl group of an alkenyl group-containing epoxy resin.

[0014]

embedded image (However, in the formula, R represents a substituted or unsubstituted monovalent hydrocarbon group or an alkoxy group, a is a number from 0.01 to 1, and b is a number from 1 to 3. The number of silicon atoms in one molecule is
The hydrogen atoms are an integer of 1 to 400, and the number of hydrogen atoms directly bonded to silicon atoms in one molecule is an integer of 1 or more. )

00
[15] Here, the alkenyl group-containing epoxy resin can be obtained by epoxidizing an alkenyl group-containing phenol resin with epichlorohydrin, or by partially reacting a suitable epoxy resin with 2-allylphenol or the like. Specific examples of this alkenyl group-containing epoxy resin include the following compounds. Note that p and q in the following formula are not particularly limited, but are usually integers in the range of 1<p<10 and 1<q<3.

[0016]

[C4]

Further, the organosilicon compound represented by the above formula (1) may be any compound having at least one ≡SiH group in one molecule, and specifically hydrogen methyl polysiloxane at both ends. , hydrogen-terminated hydrogen methyl phenyl polysiloxane, both-terminated hydrogen methyl (2-trimethoxysilylethyl) polysiloxane, and the like are preferably used. More specifically, those represented by the following structural formula can be exemplified. In addition, n in the following structural formula is a number from 20 to 200.

[0018]

[C5]

[0019] Generally, organopolysiloxane is
In the case of the same silicone content, as the degree of polymerization increases, crack resistance and high glass transition point improve, but dispersibility and adhesion to elements tend to decrease. For this reason, it is preferable to introduce a side chain as shown by the following structural formula into the organopolysiloxane to improve the adhesion to the device.

[0020]

[C6]

This organopolysiloxane has a polymerization degree of 1
-400, particularly preferably about 30-200; if the degree of polymerization is less than 1, it may be difficult to impart flexibility and a high glass transition point; if it exceeds 400, the copolymerization degree Obtaining such a combination becomes extremely difficult in terms of synthesis technology, and even if it is obtained, it becomes difficult to easily disperse it, and the object of the present invention may not be achieved.

[0022] The silicone-modified epoxy resin as component (C) is composed of the above alkenyl group-containing epoxy resin and the above formula (1).
It can be obtained by a known method such as heating and reacting an organopolysiloxane having ≡SiH represented by ≡SiH in the presence of a platinum-based catalyst such as chloroplatinic acid.

The amount of component (C) to be blended is not particularly limited, but should be 0.5 to 60 parts by weight, particularly 2 to 50 parts by weight, based on 100 parts by weight of the above-mentioned curable epoxy resin. is preferred. If the amount of component (C) is less than 0.5 parts by weight, satisfactory dimensional stability may not be obtained, while if it exceeds 60 parts by weight, mechanical strength tends to decrease.

Next, as the gap agent of component (D),
It is sufficient that the short diameter is 3 to 10 μm, and inorganic or organic fillers conventionally used as gap agents in liquid crystal sealing materials can be used, and any filler that can be set to a predetermined dimension can be used. Although any shape can be used, it is particularly preferable to use a spherical or rod-like shape. In this case, if a rod-shaped rod is used, the length is preferably 5 to 40 times the short axis (diameter). Specifically, this gap agent is
Examples include inorganic fillers such as glass fibers, glass beads, and alumina, and organic fillers such as phenol resins with three-dimensional structures and polystyrene resins.

This gap agent (D) is used to set the thickness of the liquid crystal sealing material, and its blending amount is 0% of all components.
．． The content is preferably 1 to 5% by weight. The blending amount is 0.1
If it is less than 5% by weight, it may not be possible to ensure the desired thickness when used as a liquid crystal sealing material, etc.
If the amount exceeds % by weight, only the cost will increase and no significant effect will be seen.

The fine powder silica of component (E) has an average particle diameter of 0.2 to 3 μm, preferably when the average particle diameter is c and the short axis of the gap agent of component (D) is d. c<e
The content of coarse particles having a particle size of e or more expressed as ≦3/5d is 0.5% by weight or less. This (E) component is
It is blended to control the shape of the sealing material, reduce the coefficient of linear expansion, and prevent the bleeding of the resin component, and if the average particle size is outside the above range, these effects will not be sufficiently achieved. It is something that cannot be obtained.

[0027] The blending amount of component (E) is 10 to 10% of the total components.
The content is preferably 60% by weight, more preferably 20 to 60% by weight; if it is less than 10% by weight, the above-mentioned effects will not be sufficiently exhibited, while if it exceeds 60% by weight, the viscosity of the composition will increase. , workability may be poor.

The epoxy resin composition of the present invention has the above-mentioned (A
) to (E), but various additives may be added in addition to the above components as necessary. For example, carbon-functional silane for improving adhesion, pigments such as carbon black, dyes, antioxidants, surface treatment agents such as γ-glycidoxypropyltrimethoxysilane, etc. can be added as appropriate. .

The epoxy resin composition of the present invention has the above-mentioned (A
) to (E) and various additives, and in this case, there is no particular restriction on the mixing order of each component, but
First, an epoxy resin containing components (A) and (B), which are the main ingredients of the composition of the present invention, and a silicone-modified epoxy resin as a component (C) are mixed, and this mixture is added to (C) to (E).
) components and various additives are preferably blended. In this case, the viscosity of the mixture containing component (A), component (B), and component (C) was determined using a BH viscometer at 25°C.
rpm (hereinafter the same) is preferably 10,000 poise or less, especially in the case of a liquid composition, 500 poise or less, especially 200 poise or less, and finally components (C) to (E) are added to this. In addition, the composition preferably has a viscosity of 10,000 poise or less.

The epoxy resin composition of the present invention can be suitably used as a liquid crystal sealing material, thereby making it possible to obtain a liquid crystal device with excellent dimensional accuracy and without bleeding or elution of sealing material components. .

[0031]

EXAMPLES The present invention will be specifically explained below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. Incidentally, before the Examples and Comparative Examples, a manufacturing example of a silicone-modified epoxy resin is shown as a reference example.

[Reference Example] 300 g of an epoxidized phenol novolac resin (epoxy equivalent: 195) with a softening point of 80° C. is placed in a 1-liter four-necked flask equipped with a reflux condenser, thermometer, stirrer, and dropping funnel. Then, a mixture of 32 g of 2-allylphenol and 1 g of tributylamine was added dropwise to the mixture over 10 minutes while stirring at 110°C, and the mixture was further stirred at 110°C for 2 hours. Unreacted 2-allylphenol and tributylamine were distilled off from the resulting contents under reduced pressure to obtain an allyl group-containing epoxy resin (allyl equivalent: 1490, epoxy: 235).

Next, 120 g of the allyl group-containing epoxy resin obtained, 100 g of methyl isobutyl ketone, 200 g of toluene, and 0.0 g of a 2-ethylhexanol-modified chloroplatinic acid solution having a platinum concentration of 2% were placed in a four-necked flask similar to the above.
After 1 hour of azeotropic dehydration, 80 g of organopolysiloxane (compounds A and B) represented by the following structural formula was added dropwise over 30 minutes at reflux temperature, and the mixture was further stirred at the same temperature for 4 hours to react. After that, the obtained reaction product was washed with water, and the solvent was distilled off under reduced pressure to obtain a crude reaction product.

[0034]

[C7]

100 g of this crude reaction product was mixed with 38 g of acetone.
0 g, add 140 g of water, and leave to stand to obtain a solution that separates into two layers. After discarding the upper layer of this solution, 200 g of acetone is added again and mixed, and 50 g of water is added to this. I left it alone. The lower layer was collected from the resulting two-layer separated solution, and acetone and water were distilled off under reduced pressure to obtain silicone-modified epoxy resins I and II shown in Table 1 below.

[0036]

[Table 1]

[Example, Comparative Example] Epoxidized phenol A (manufactured by Yuka Shell Co., Ltd., Epicoat 282) (Table 3 shows
(simply referred to as epoxy resin), 4-methylhexahydrophthalic anhydride (Rikacid MH700, manufactured by Shin Nihon Rika Co., Ltd.)
(simply referred to as acid anhydride in Table 3), silicone-modified epoxy resins I and II produced in the above reference examples, and silica powders A to C shown in Table 2 were mixed in the proportions shown in Table 3.

[0038]

[Table 2]

[0039] 2 parts by weight of glass fiber (short side 5 μm, long side 50 to 100 μm) was added as a gap agent to the obtained mixture;
0.5 parts by weight of 3-glycidoxypropyltrimethoxysilane, 1,8-diazabicycloundecene-7 (DBU
) was mixed uniformly to obtain six types of epoxy resin compositions.

The viscosity at 25° C. (BH viscometer, 4 rpm) of each of the obtained liquid crystal sealing materials was measured, and the following tests were also conducted. The results are shown in Table 3.

[0041] Two glass plates are pasted together to form a seal part.
The above liquid crystal sealing material was applied to a 0x18 mm square with a line width of 0.3 mm and a thickness of 5 μm, and cured at 120° C. for 4 hours. After cooling this to 25℃,
．． The presence or absence of voids of 1 mm or more was examined, and the maximum thickness of the seal portion and the maximum length of the bleed portion were measured. The results are shown in Table 3.

[0042]

[Table 3]

As is clear from the results in Table 3, when the epoxy resin composition of the present invention is used as a liquid crystal sealing material, it has excellent dimensional accuracy and can prevent the occurrence of bleeding and voids as much as possible. It was confirmed that it is possible to reliably manufacture a liquid crystal device with stable quality.

[0044]

[Effects of the Invention] As explained above, according to the epoxy resin composition of the present invention, when used as a liquid crystal sealing material, it has excellent dimensional accuracy and can prevent the occurrence of bleeding and voids as much as possible. Therefore, it is suitably used as a liquid crystal sealing material, and a liquid crystal device sealed with this composition has excellent dimensional accuracy and stability in use.

Claims (3)

[Claims] Claim 1: (A) an epoxy resin, (B) a curing agent, and (C) an organosilicon compound represented by the following formula (1) in the alkenyl group of the alkenyl group-containing epoxy resin, ≡SiH.
A silicone-modified epoxy resin with added groups, and
Chemical formula 1] (However, in the formula, R represents a substituted or unsubstituted monovalent hydrocarbon group or an alkoxy group, a is a number from 0.01 to 1, and b is a number from 1 to 3. The number of silicon atoms in the molecule is
It is an integer of 1 to 400, and the number of hydrogen atoms directly bonded to silicon atoms in one molecule is an integer of 1 or more. ) (D) A gap agent consisting of an inorganic or organic filler having a short diameter of 3 to 10 μm; and (E) Finely powdered silica having an average particle size of 0.2 to 3 μm. Resin composition. [Claim 2] The viscosity at 25°C is BH type viscometer 4.
The epoxy resin composition according to claim 1, which has a rotational speed of 10,000 poise or less at rpm. 3. A cured product of the epoxy resin composition according to claim 1 or 2.