Liquid crystal sealing agent and liquid crystalline display cell using the same Number:7,521,100 from the United States Patent and Trademark Office (PTO) owispatent The present invention relates to a sealant for liquid crystals having extremely low contamination nature to a liquid crystal, excellent coatability and bondability to a substrate, long service life and pot life and high adhesive strength. A sealant for liquid crystals of the present invention is characterized by comprising (a) an epoxy resin represented by general formula (1): ##STR00001## (wherein a represents an integer of 2 to 4; n represents 0 to 3 (average value); R represents a divalent hydrocarbon group of 2 to 6 carbon atoms; A represents a polyvalent aromatic group; and G represents a glycidyl group, provided that when n is 0, (a) an epoxy resin represented by general formula (1) is a bisphenol S-type.), (b) a thermo-curing agent, (c) and a filler having average particle diameter of not larger than 3 .mu.m.<H crystalline, display, Liquid, crystal, , 7521100.html, Patent, pto, 7521100

Title: Liquid crystal sealing agent and liquid crystalline display cell using the same

Abstract: The present invention relates to a sealant for liquid crystals having extremely low contamination nature to a liquid crystal, excellent coatability and bondability to a substrate, long service life and pot life and high adhesive strength. A sealant for liquid crystals of the present invention is characterized by comprising (a) an epoxy resin represented by general formula (1): ##STR00001## (wherein a represents an integer of 2 to 4; n represents 0 to 3 (average value); R represents a divalent hydrocarbon group of 2 to 6 carbon atoms; A represents a polyvalent aromatic group; and G represents a glycidyl group, provided that when n is 0, (a) an epoxy resin represented by general formula (1) is a bisphenol S-type.), (b) a thermo-curing agent, (c) and a filler having average particle diameter of not larger than 3 .mu.m.

Patent Number: 7,521,100 Issued on 04/21/2009 to Imaizumi, et al.

Inventors: Imaizumi; Masahiro (Kita-ku, JP), Asano; Toyofumi (Saitama, JP), Ochi; Naoyuki (Saitama, JP), Hirano; Masahiro (Ageo, JP), Ichimura; Sumio (Kita-ku, JP), Kudo; Masaru (Saitama, JP), Oshimi; Katsuhiko (Saitama, JP), Nakanishi; Masataka (Saitama, JP), Akatsuka; Yasumasa (Saitama, JP), Nishihara; Eiichi (Kita-ku, JP), Itai; Masayuki (Sanyoonoda, JP)
Assignee: Nippon Kayaku Kabushiki Kaisha (Tokyo, JP)

Appl. No.: 10/552,183

Filed: April 6, 2004

PCT Filed: April 06, 2004

PCT No.: PCT/JP2004/004972

371(c)(1),(2),(4) Date: October 06, 2005

PCT Pub. No.: WO2004/090621

PCT Pub. Date: October 21, 2004

Foreign Application Priority Data


Apr 08, 2003 [JP]			2003-103566
Apr 08, 2003 [JP]			2003-103590

Current U.S. Class: 428/1.53 ; 156/275.3; 156/275.5; 349/153; 349/190; 428/1.5; 522/100; 525/150; 525/31; 525/396; 525/487; 528/87; 528/90

Current International Class: C09K 3/10 (20060101); C08G 59/04 (20060101); G02F 1/1339 (20060101); C08L 63/02 (20060101)

Field of Search: 428/1.5,1.53,1.55 349/153,190 525/31,330.4,150,396,487 524/502 522/100 156/275.5,275.3 528/87,90

References Cited [Referenced By]

U.S. Patent Documents


4284574	August 1981	Bagga
4845172	July 1989	Brytus et al.
5150239	September 1992	Watanabe et al.
5596023	January 1997	Tsubota et al.
6010824	January 2000	Komano et al.
6120858	September 2000	Hirano et al.
6287745	September 2001	Yamamura et al.
2002/0176046	November 2002	Kitamura et al.
2003/0147034	August 2003	Kojima
2005/0222300	October 2005	Ikezawa et al.
2006/0004140	January 2006	Asano et al.
2006/0014873	January 2006	Ikezawa et al.

Foreign Patent Documents


0 632 080	Jan., 1995	EP
1 061 402	Dec., 2000	EP
61-186376	Aug., 1986	JP
63-179323	Jul., 1988	JP
2-223954	Sep., 1990	JP
5-295087	Nov., 1993	JP
6-073164	Mar., 1994	JP
6-73164	Mar., 1994	JP
07-013135	Jan., 1995	JP
08-033357	Feb., 1996	JP
9-005759	Jan., 1997	JP
10-239694	Sep., 1998	JP
11-109388	Apr., 1999	JP
2001-75109	Mar., 2001	JP
2001-133794	May., 2001	JP
2001-172475	Jun., 2001	JP
2002-182188	Jun., 2002	JP
2002-256058	Sep., 2002	JP
2002-317172	Oct., 2002	JP
2003-176332	Jun., 2003	JP
2003-321532	Nov., 2003	JP
2004-137425	May., 2004	JP
2004-198464	Jul., 2004	JP

Other References

The Supplemental European Search Report dated Feb. 15, 2007. cited by other .
The International Search Report dated Jul. 27, 2004. cited by other .
Database WPI Week 200144, Derwent Publications Ltd, London, XP-002417512 (2001-414008) May 18, 2001. cited by other .
European communication dated Feb. 9, 2007. cited by other .
The International Search Report dated Feb. 24, 2004. cited by other .
Office Actions in U.S. Appl. No. 10/532,705 dated Aug. 1, 2007, Oct. 26, 2007 and May 7, 2008. cited by other.

Primary Examiner: Wu; Shean C
Attorney, Agent or Firm: Nields, Lemack & Frame, LLC

Claims

The invention claimed is:

1. A sealant for liquid crystals characterized by comprising an epoxy resin (a) represented by general formula (1): ##STR00012## (wherein a represents an integer of 2 to 4; n represents 1 to 1.5 (average value); R represents --CH.sub.2--CH.sub.2--; A represents a polyvalent aromatic group selected from a di- or trivalent phenol or naphthol residue; a di- to tetravalent aromatic group formed by bonding 2 to 4 benzene rings or naphthalene rings (aliphatic group(s) of 1 to 6 carbon atoms may be present as a substituent on the benzene ring or naphthalene ring, and the total number of bonding arms on the ring is 2 to 4) through single bond, divalent aliphatic hydrocarbon residue(s) (which may be substituted with a phenyl group) of 1 to 3 carbon atoms, oxygen atom(s) or a sulfur atom(s) (which may be in a sulfonyl form); or a residue obtained by removing a hydroxyl group from a novolac resin; and G represents a glycidyl group, (b) a thermo-curing agent, and (c) a filler having average particle diameter of not larger than 3 .mu.m.

2. The sealant for liquid crystals according to claim 1, wherein the polyvalent aromatic group is a divalent aromatic group represented by the formula: -ph-X-ph- {wherein, ph represents a phenylene group (which may have an aliphatic group of 1 to 6 carbon atoms as a substituent); X represents a cross-linking group represented by --O--, --S--, --S(O).sub.2-- or the formula: --C(R.sub.3)(R.sub.4)-- (wherein R.sub.3 and R.sub.4 are bondned to form a fluorene ring of C(R.sub.3)(R.sub.4))}.

3. The sealant for liquid crystals according to claim 1, wherein the epoxy resin (a) represented by general formula (1) is a bisphenol S-type; and n represents 1 to 1.5 (average value).

4. The sealant for liquid crystals according to claim 3, wherein the epoxy resin (a) is an epoxy resin represented by general formula (2): ##STR00013## (wherein n.sub.1 and n.sub.2 represent each independently 1 to 1.5; R represents --CH.sub.2--CH.sub.2--; R.sub.1 and R.sub.2 represent each independently a hydrogen atom or a monovalent hydrocarbon group of 1 to 6 carbon atoms; and G represents a glycidyl group).

5. The sealant for liquid crystals according to claim 4, wherein the epoxy resin (a) is an epoxy resin represented by general formula (3): ##STR00014## (wherein n.sub.1 and n.sub.2 represent each independently 1 to 1.5; R represents --CH.sub.2--CH.sub.2--; and G represents a glycidyl group).

6. The sealant for liquid crystals according to claim 1, wherein the epoxy resin (a) is an epoxy resin represented by general formula (4): ##STR00015## (wherein n.sub.1 and n.sub.2 represent each independently a positive number of 1 to 1.5; R represents --CH.sub.2--CH.sub.2--; and G represents a glycidyl group).

7. The sealant for liquid crystals according to claim 1, wherein the thermo-curing agent (b) is polyfunctional dihydrazides or a polyvalent phenol compound.

8. The sealant for liquid crystals according to claim 7, wherein the polyfunctional dihydrazides are isophthalic acid hydrazide, dihydrazides having valine hydantoin skeleton, or adipic acid dihydrazide.

9. The sealant for liquid crystals according to claim 1, wherein mixing ratio of the epoxy resin (a) and the thermo-curing agent (b) is 0.8 to 3 equivalent of the active hydrogen of the thermo-curing agent (b)based on 1 equivalent of the epoxy group of the epoxy resin (a); and the content of the filler (c) having average particle diameter of not larger than 3 .mu.m in the sealant for liquid crystals is from 5 to 40% by weight.

10. The sealant for liquid crystals according to claim 1, further comprising, as a component, a curable resin (d) having a (meth)acrylic group and a radical-forming type photopolymerization initiator (e).

11. The sealant for liquid crystals according to claim 10, wherein the curing resin (d) having a (meth)acrylic group is a (meth)acrylate of an aromatic epoxy resin.

12. The sealant for liquid crystals according to claim 11, wherein the (meth)acrylate of an aromatic epoxy resin is a (meth)acrylate of a bisphenol-type epoxy resin.

13. The sealant for liquid crystals according to claim 10, wherein the curing resin (d) having a (meth)acrylic group is a (meth)acrylate of (a) an epoxy resin represented by the general formula (1).

14. The sealant for liquid crystals according to claim 10, wherein the radical-forming photopolymerization initiator (e) is a carbazole-series photopolymerization initiator or an acridine-series photopolymerization initiator.

15. The sealant for liquid crystals according to claim 10, further comprising a silane coupling agent (f).

16. The sealant for liquid crystals according to claim 15, further comprising an ion scavenger (g).

17. The sealant for liquid crystals according to claim 16, wherein the ion scavenger is at least one kind selected from a group consisting of a bismuth oxide-series ion scavenger, an antimony oxide-series ion scavenger, a titanium phosphate-series ion scavenger, a zirconium phosphate-series ion scavenger and a hydrotalcite-series ion scavenger.

18. The sealant for liquid crystals according to claim 16, wherein the contents in the sealant for liquid crystals fall in the ranges of 5 to 80% of the epoxy resin (a) component, 2 to 20% of the thermo-curing agent (b) component, 5 to 50% of the filler (c) component having average particle diameter of not larger than 3 .mu.m, 5 to 80% of the curable resin (d) component having a (meth)acrylic group, 0.1 to 3% of the radical-forming photopolymerization initiator (e) component, 0.2 to 2% of the silane coupling agent (f) component and 0.2 to 20% of the ion scavenger (g) component.

19. A liquid crystal display cell sealed by a cured product of the sealant for liquid crystals according to claim 1.

20. A method for manufacturing a liquid crystal display cell characterized, in the liquid crystal display cell composed of two substrates, by dropping a liquid crystal inside a bank of the sealant for liquid crystals according to claim 1, that is formed on one substrate, thereafter bonding the other substrate thereto and then curing the sealant for liquid crystals.

21. A composition characterized by comprising (a) an epoxy resin represented by general formula (1): ##STR00016## (wherein a represents an integer of 2 to 4; n represents 1 to 1.5 (average value); R represents --CH.sub.2--CH.sub.2--; A represents a polyvalent aromatic group selected from a di- or trivalent phenol or naphthol residue; a di- to tetravalent aromatic group formed by bonding 2 to 4 benzene rings or naphthalene rings (aliphatic group(s) of 1 to 6 carbon atoms may be present as a substituent on the benzene ring or naphthalene ring, and the total number of bonding arms on the ring is 2 to 4) through single bond, divalent aliphatic hydrocarbon residue(s) (which may be substituted with a phenyl group) of 1 to 3 carbon atoms, oxygen atom(s) or a sulfur atom(s) (which may be in a sulfonyl form); or a residue obtained by removing a hydroxyl group from a novolac resin; and G represents a glycidyl group, (b) a thermo-curing agent, and (c) a filler having average particle diameter of not larger than 3 .mu.m.

22. The composition according to claim 21, characterized by further comprising the curable resin (d) having a (meth)acryl group, the radical-forming photopolymerization initiator (e), the silane coupling agent (f) and the ion scavenger (g).

Description

TECHNICAL FIELD

The present invention relates to a sealing agent (sealant) for liquid crystals, a liquid crystalline display cell using the sealant and a composition suitable for the sealant for liquid crystals. More specifically, the present invention relates to a sealant for liquid crystals suitable for manufacturing a liquid crystal display cell by a liquid-crystal dropping technique (liquid-crystal One Drop Filling; ODF), a liquid crystal display cell manufactured using the sealant and a composition suitable for the sealant for liquid crystals.

BACKGROUND ART

In recent years, along with demands for large-size liquid crystal display cells, a so-called liquid-crystal dropping technique (liquid-crystal One Drop Filling; ODF), which has higher productivity, has been proposed as a manufacturing method of a liquid-crystal display cell (see Japanese Patent Application Laid-Open Nos. 63-179323 and 10-239694). In these methods, a liquid crystal display cell in which a liquid crystal is sealed is manufactured by dropping the liquid crystal inside a bank of a sealant for liquid crystals formed on one substrate, thereafter bonding the other substrate thereto.

In the liquid-crystal dropping technique, however, the sealant for liquid crystals in uncured state is made in contact with the liquid crystal, with the result that there is a problem that, upon manufacturing a liquid crystal display cell, some components of the sealant for liquid crystals are dissolved in the liquid crystal to cause reduction in the specific resistance of the liquid crystal; consequently, this technique has not spread as a mass-producing method for liquid crystal display cells.

With respect to a curing method after the bonding process of the sealant for liquid crystals in the liquid-crystal dropping technique, three methods including a thermo-curing method, a photo-curing method and a photo-thermo-curing method, have been proposed. The thermo-curing method has problems in that liquid crystal tends to leak from the sealant for liquid crystals that is being cured with reduced viscosity due to expansion of the heated liquid crystal, and in that some components of the sealant for liquid crystals with the reduced viscosity tend to be dissolved in the liquid crystal, and these problems are difficult to be resolved with the result that this technique has not been practically used.

Here, with respect to the sealant for liquid crystals to be used in the photo-curing method, two kinds of photopolymerization initiators, that is, a cation polymerizable type and a radical polymerizable type, have been proposed. With respect to the sealant for liquid crystals of the cation polymerizable type, since ions are generated upon photo-curing, the ion components are eluted in the liquid crystal in a contact state when the sealant of this type is used in the liquid-crystal dropping technique, resulting in a problem of a reduced specific resistance in the liquid crystal. Another problem with both of the photo-curing methods of the cation polymerizable type and the radical polymerizable type is that since a light-shield portion in which the sealant for liquid crystals is not exposed to light is left due to a metal wiring portion of an alley substrate of the liquid crystal display cell and a black matrix portion of a color filter substrate, the corresponding light-shield portion is uncured.

As described above, the thermo-curing and photo-curing methods have various problems, and in actual operation, the photo-thermo curing method is considered to be the most practical technique. The photo-thermo curing method is characterized by that the sealant for liquid crystals sandwiched by substrates is irradiated by light for primary curing, and thereafter heated for secondary curing. With respect to properties required for the sealant for liquid crystals to be used for the photo-thermo curing method, it is important to prevent the sealant for liquid crystals from contaminating the liquid crystal in respective processes before and after the light irradiation as well as before and after the heat-curing processes, and it is necessary to properly address the problem with the above-mentioned light-shield portion, that is, the problem of elution of the sealant components into the liquid crystal when the portion uncured by light irradiation is thermally cured. The following solutions to the problems are proposed: (1) a low-temperature fast curing process is carried out prior to the elution of the sealant components; and (2) the sealant is made from components that hardly elute into the liquid crystal compositions. Of course, the low-temperature fast curing process simultaneously causes degradation in the pot life during use, resulting in a serious problem in practical use. For this reason, in order to achieve a sealant for liquid crystals that provides longer pot life, and hardly contaminates liquid crystals, it is necessary to comprise components that are hardly eluted into the liquid crystal composition. However, commonly well known epoxy resins, such as a bisphenol A type epoxy resin and a bisphenol F type epoxy resin, have a good compatibility with liquid crystals with the result that these resins are not suitable for the constituent component for the sealant from the viewpoint of contamination-preventive property.

Japanese Patent Application Laid-Open No. 2001-133794 has proposed that a partially (meth)acrylated-bisphenol A-type epoxy resin disclosed in Japanese Patent Application Laid-Open No. 5-295087 should be used as a main resin component for the sealant for liquid crystals for use in the liquid-crystal dropping technique. In this case, however, although the (meth)acrylated resin has reduced solubility to liquid crystals, the degree of the reduction is not sufficient, and it is also difficult to solve a problem of the un-reacted remaining raw epoxy resin that contaminates liquid crystals.

As described above, the conventionally proposed photo-thermo curing type sealant for liquid crystals used in the liquid-crystal dropping technique is far from satisfying all the properties such as liquid crystal contamination-preventive property, adhesive strength, workable time at room temperature and low-temperature curing property.

The objective of the present invention is to develop a sealant for liquid crystals to be used for a liquid crystal display device to be manufactured by a liquid-crystal dropping technique, and more specifically, to develop a sealant for liquid crystals to be used for a liquid crystal display device to be manufactured by the liquid-crystal dropping technique comprising dropping a liquid crystal inside a bank of a sealant for liquid crystals formed on one substrate, thereafter bonding the other substrate thereto, irradiating a liquid-crystal sealed portion with light, and then heat-curing it. In other words, the objective of the present invention is to provide a sealant for liquid crystals which hardly contaminates liquid crystals throughout the manufacturing processes, shows excellent coatability, bondability and adhesive strength when applied to a substrate, and has long workable time (pot life) at room temperature and excellent low-temperature curing property.

DISCLOSURE OF THE INVENTION

As the result of extensive investigations a way to solve the above-mentioned problems, the present inventors have found that a sealant for liquid crystals comprising: (a) an epoxy resin represented by general formula (1) (that is, a bisphenol S-type epoxy resin or an epoxy resin having an alkylene oxide unit in the structure); (b) a thermo-curing agent; and (c) a filler having average particle diameter of not larger than 3 .mu.m can attain the above objectives, and thus completed the present invention.

The present invention relates to the following aspects:

1. A sealant for liquid crystals characterized by comprising (a) an epoxy resin represented by general formula (1):

##STR00002## (wherein a represents an integer of 2 to 4; n represents 0 to 3 (average value); R represents a divalent hydrocarbon group of 2 to 6 carbon atoms; A represents a polyvalent aromatic group; and G represents a glycidyl group, provided that when n is 0, (a) an epoxy resin represented by general formula (1) is a bisphenol S-type.), a thermo-curing agent (b), and a filler (c) having average particle diameter of not larger than 3 .mu.m.

2. The sealant for liquid crystals according to the above aspect 1, wherein the polyvalent aromatic group is a di- or trivalent phenol or naphthol residue; a di- to tetravalent aromatic group formed by bonding 2 to 4 benzene rings or naphthalene rings (the benzene ring or naphthalene ring may have an aliphatic group of 1 to 6 carbon atoms as a substituent, and the total bonding arms on the ring is 2 to 4) through single bond, a divalent aliphatic hydrocarbon residue (which may be substituted with a phenyl group) of 1 to 3 carbon atoms, an oxygen atom or a sulfur atom (which may be in a form of a sulfonyl); or a residue obtained by removing a hydroxyl group from a novolac resin.

3. The sealant for liquid crystals according to the above aspect 2, wherein the polyvalent aromatic group is a divalent aromatic group represented by the formula: -ph-X-ph- {wherein ph represents a phenylene group (which may have an aliphatic group of 1 to 6 carbon atoms as a substituent); X represents a cross-linking group represented by --O--, --S--, --S(O).sub.2-- or the formula: --C(R.sub.3)(R.sub.4)-- (wherein R.sub.3 and R.sub.4 represent each independently a hydrogen atom or a methyl group, or R.sub.3 and R.sub.4 are bonded to form a fluorene ring of C(R.sub.3)(R.sub.4))}.

4. The sealant for liquid crystals according to the above aspect 1, wherein (a) epoxy resin represented by general formula (1) is a bisphenol S-type; and n represents 0 to 3 (average value).

5. The sealant for liquid crystals according to the above aspect 4, wherein (a) epoxy resin is an epoxy resin represented by general formula (2):

##STR00003## (wherein n.sub.1 and n.sub.2 represent each independently 0.5 to 3; R represents a divalent hydrocarbon group of 2 to 6 carbon atoms; R.sub.1 and R.sub.2 represent each independently a hydrogen atom or a monovalent hydrocarbon group of 1 to 6 carbon atoms; and G represents a glycidyl group).

6. The sealant for liquid crystals according to the above aspect 5, wherein (a) epoxy resin is an epoxy resin represented by general formula (3):

##STR00004## (wherein n.sub.1 and n.sub.2 represent each independently 0.5 to 3; R represents a divalent hydrocarbon group of 2 to 6 carbon atoms; and G represents a glycidyl group).

7. The sealant for liquid crystals according to the above aspect 1, wherein (a) epoxy resin is an epoxy resin represented by general formula (4):

##STR00005## (wherein n.sub.1 and n.sub.2 represent each independently a positive number of 0.5 to 3; R represents a divalent hydrocarbon group of 2 to 6 carbon atoms; and G represents a glycidyl group).

8. The sealant for liquid crystals according to any one of the above aspects 1 to 7, wherein --O--R-- is --O--CH.sub.2CH.sub.2--.

9. The sealant for liquid crystals according to above aspects 1 and 4, wherein n represents 1 to 1.5.

10. The sealant for liquid crystals according to any one of the above aspects 1 to 7, wherein the thermo-curing agent (b) is polyfunctional dihydrazides or a polyvalent phenol compound.

11. The sealant for liquid crystals according to the above aspect 10, wherein the polyfunctional dihydrazides are isophthalic acid hydrazide, dihydrazides having valine hydantoin skeleton, or adipic acid dihydrazide.

12. The sealant for liquid crystals according to any one of the above aspects 1 to 11, wherein mixing ratio of the epoxy resin (a) and the thermo-curing agent (b) is 0.8 to 3 equivalent of the active hydrogen of the thermo-curing agent (b)based on 1 equivalent of the epoxy group of the epoxy resin (a); and the content of (c) filler having average particle diameter of not larger than 3 .mu.m in the sealant for liquid crystals is from 5 to 40% by weight.

13. The sealant for liquid crystals according to any one of the above aspects 1 to 12, further comprising, as a component, (d) a curable resin having a (meth)acrylic group and (e) a radical-forming type photopolymerization initiator.

14. The sealant for liquid crystals according to the above aspect 13, wherein the curing resin (d) having a (meth)acrylic group is a (meth)acrylate of an aromatic epoxy resin.

15. The sealant for liquid crystals according to the above aspect 14, wherein the (meth)acrylate of an aromatic epoxy resin is a (meth)acrylate of a bisphenol-type epoxy resin.

16. The sealant for liquid crystals according to the above aspect 13, wherein the curing resin (d) having a (meth)acrylic group is a (meth)acrylate of (a) epoxy resin represented by the general formula (1) wherein n is not 0.

17. The sealant for liquid crystals according to any one of the above aspects 13 to 16, wherein the radical-forming photopolymerization initiator (e) is a carbazole-series photopolymerization initiator or an acridine-series photopolymerization initiator.

18. The sealant for liquid crystals according to any one of the above aspects 1 to 17, further comprising (f) a silane coupling agent.

19. The sealant for liquid crystals according to any one of the above aspects 1 to 18, further comprising (g) an ion scavenger.

20. The sealant for liquid crystals according to the above aspect 19, wherein the ion scavenger is at least one kind selected from a group consisting of a bismuth oxide-series ion scavenger, an antimony oxide-series ion scavenger, a titanium phosphate-series ion scavenger, a zirconium phosphate-series ion scavenger and a hydrotalcite-series ion scavenger.

21. The sealant for liquid crystals according to the above aspect 19 or 20, wherein the contents in the sealant for liquid crystals fall in the ranges of 5 to 80% of the epoxy resin (a) component, 2 to 20% of the thermo-curing agent (b) component, 5 to 50% of the filler (c) component having average particle diameter of not larger than 3 .mu.m, 5 to 80% of the curable resin (d) component having a (meth)acrylic group, 0.1 to 3% of the radical-forming photopolymerization initiator (e) component, 0.2 to 2% of the silane coupling agent (f) component and 0.2 to 20% of the ion scavenger (g) component.

22. A liquid crystal display cell sealed by a cured product of the sealant for liquid crystals according to any one of the above aspects 1 to 21.

23. A method for manufacturing a liquid crystal display cell characterized, in the liquid crystal display cell composed of two substrates, by dropping a liquid crystal inside a bank of the sealant for liquid crystals according to any one of the above aspects 1 to 22, that is formed on one substrate, thereafter bonding the other substrate thereto and then curing the sealant for liquid crystals.

24. A composition characterized by comprising (a) an epoxy resin represented by general formula (1):

##STR00006## (wherein a represents an integer of 2 to 4; n represents 0 to 3 (average value); R represents a divalent hydrocarbon group of 2 to 6 carbon atoms; A represents a polyvalent aromatic group; and G represents a glycidyl group, provided that when n is 0, (a) the epoxy resin represented by general formula (1) is a bisphenol S-type.), (b) a thermo-curing agent, and (c) a filler having average particle diameter of not larger than 3 .mu.m.

25. The composition according to the above aspect 24, characterized by further comprising (d) a curable resin having a (meth)acryl group, (e) a radical-forming photopolymerization initiator, (f) a silane coupling agent and (g) an ion scavenger.

BEST MODE FOR CARRYING OUT THE INVENTION

A sealant for liquid crystals and a composition of the present invention are characterized by comprising (a) an epoxy resin represented by general formula (1), (b) a thermo-curing agent and (c) a filler having average particle diameter of not larger than 3 .mu.m.

The divalent hydrocarbon group of 2 to 6 carbon atoms represented by R in general formula (1) may be any of saturated, unsaturated, chain, cyclic or a combination thereof, and usually an alkylene group of 2 to 6 carbon atoms is preferable.

The polyaromatic group represented by A in general formula (1) is not particularly limited, as long as it is an aromatic residue obtained by removing a hydroxyl group from an aromatic polyvalent alcohol having not less than two phenolic hydroxyl groups. For example, it includes a di- or trivalent phenol or naphthol residue; a di- to tetravalent aromatic group formed by bonding 2 to 4 benzene rings or naphthalene rings (aliphatic group(s) of 1 to 6 carbon atoms may be present as a substituent on the benzene ring or naphthalene ring, and the total number of bonding arms on the ring is 2 to 4) through single bond, divalent aliphatic hydrocarbon residue(s) (which may be substituted with a phenyl group) of 1 to 3 carbon atoms, oxygen atom(s) or a sulfur atom(s) (which may be in a sulfonyl form); or a residue obtained by removing a hydroxyl group from a novolac resin. More preferably, the polyvalent aromatic group includes a divalent aromatic group represented by the formula: -ph-X-ph- {wherein ph represents a phenylene group (which may have an aliphatic group of 1 to 6 carbon atoms as a substituent); X represents --O--, --S--, --S(O).sub.2-- or a cross-linking group represented by the formula: --C(R.sub.3)(R.sub.4)-- (wherein R.sub.3 and R.sub.4 represent each independently a hydrogen atom or a methyl group, or R.sub.3 and R.sub.4 are bonded to form a fluorene ring with C(R.sub.3)(R.sub.4)).

An epoxy resin (a) to be used for the present invention is obtained, when n in general formula (1) is 0 (that is, when the epoxy resin (a) is a bisphenol S-type epoxy resin), by subjecting a raw material bisphenol Ss such as bisphenol S and bis-C1-C6 hydrocarbon group-substituted phenol S (bisphenol S having a hydrocarbon substituent of 1 to 6 carbon atoms on the benzene ring); bis(hydroxyl-alkoxyphenyl)sulfones obtained by reacting the bisphenol Ss with an alkylene oxide, and the like; or a novolac containing bisphenol Ss in the backbone molecule such as bisphenol S novolac, to react with an epihalohydrin. On the other hand, an epoxy resin (a) is obtained, when n is not 0, by subjecting a raw material aromatic polyvalent alcohol, preferably an aromatic polyvalent alcohol corresponding to the above mentioned group as an example of A, more preferably a phenol compound (a polyvalent phenol or an aromatic polyvalent alcohol obtained by bonding mono- or polyvalent phenols through a cross-linking group), to addition reaction with an alkylene oxide and then reacting a hydroxyl group of thus obtained compound with epihalohydrin.

The aromatic polyvalent alcohol to be used as a raw material is not particularly limited as long as it is an aromatic polyvalent alcohol and preferably includes a polyvalent phenol compound, for example, bisphenols such as bisphenol A, bisphenol F, bisphenol E, bisphenol S, bisphenolfluorene, biscresolfluorene, oxydicresol and thiodiphenol; novolacs such as phenol novolac, cresol novolac, bisphenol A novalac, bisphenol F novalac and phenol novolac having triphenolmethane skelton; polyhydric phenols having two to three hydroxyl groups such as catechol, resorcin, hydroquinone and pyrogallol; and biphenols, preferably bisphenol type (including biphenols) dihydric alcohols such as bisphenol A, bisphenol F, bisphenol E, bisphenol S, bisphenolfluorene, oxydiphenol, thiodiphenol and biphenol, and more preferably bisphenol S and bisphenolfluorene. Epihalohydrins are not limited especially, however, include epichlorohydrin, .beta.-methyl epichlorohydrin, epibromohydrin and .beta.-methylepibromohydrin, and epichlorohydrin is preferable.

Alkylene oxides which can be added to a phenol are not limited especially, as long as they are compounds corresponding to R of the general formula (I), including usual alkylene oxides compounds having two to six carbon atoms, such as ethylene oxide, propylene oxide, tetramethylene oxide, methylethylene oxide and hexamethylene oxide, and ethylene oxide is preferable from the standpoints of heat resistance and mechanical strength. Similarly, the amount of an alkylene oxide to be added is preferably 0.5 to 3 equivalent, more preferably 1.0 to 1.5 equivalent of the alkylene oxidebased on 1 equivalent of a phenol.

A sealant for liquid crystals of the present invention contains the thermo-curing agent (b). The thermo-curing agent is not particularly limited as long as it reacts with an epoxy resin by heating, usually heating to not lower than 50.degree. C. to form a cured product. It is usually important that the reaction is initiated uniformly and quickly without contamination to a liquid crystal upon heating and that time lapse-change in viscosity is less at room temperature during use. A thermo-curing agent that meets such conditions is preferable. With respect to curing condition in a liquid-crystal dropping technique, it is required for a thermo-curing agent to have low temperature curing ability under curing conditions of generally not higher than 120.degree. C. in about one hour so as to keep degradation of characteristics of a sealed liquid crystal at the minimum. Considering the above conditions, use of polyfunctional dihydrazides and polyvalent phenols is especially preferable as a thermo-curing component of a sealant for liquid crystals of the present invention.

The polyfunctional dihydrazides mean compounds having not less than 2 hydrazide groups in the molecule and any of these compounds can be used. Generally, the polyfunctional dihydrazides include an acid hydrazide having not less than 2, usually 2 to 4 acid hydrazide groups on the skeleton of an aliphatic or aromatic hydrocarbon of 2 to 20 carbon atoms. The above acid hydrazide group may be bonded to the hydantoin skeleton formed on the above hydrocarbon skeleton through an alkylene of 1 to 3 carbon atoms. In the case of the skeleton of an aromatic hydrocarbon, 1 or 2 nitrogen atoms may be contained in the skeleton.

Typical examples of polyfunctional dihydrazides include, for example, dibasic acid dihydrazides having aliphatic acid skeltone, such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, hexadecanedioic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, diglycolic acid dihydrazide, tartaric acid dihydrazide and malic acid dihydrazide; aromatic dihydrazides such as isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 1,4-benzene dihydrazide, 1,4-naphthoic acid dihydrazide, 2,6-pyridine dihydrazide, 1,2,4-benzene trihydrazide, pyromellitic acid tetrahydrazide, 1,4,5,8-naphthoic acid tetrahydrazide; dihydrazides having valine hydantoin skeltone such as 1,3-bis(hydrazinecarbonoethyl)-5-isopropylhydantoin, but are not limited thereto. When polyfunctional hydrazides are used as a curing agent, they are preferably pulverized to fine particles and dispersed uniformly. Among the polyfunctional hydrazides, isophthalic dihydrazide and dihydrazides having valine hydantoin skeleton are particularly preferable. Too large average particle diameter of the above polyfunctional hydrazides causes a problem of defective gap formation upon bonding of upper and lower glass substrates each other when a liquid crystal cell with a narrow gap is manufactured, therefore, the average particle diameter is preferably not larger than 3 .mu.m, more preferably not larger than 2 .mu.m. Moreover, for the same reason, the maximum particle diameter is preferably not larger than 8 .mu.m, more preferably not larger than 5 .mu.m. Here, particle diameter of a curing agent was measured using a laser diffraction-scattering type measuring device of particle diameter distribution (dry type) (LMS-30, manufactured by Seishin Enterprise Co., Ltd.).

When the polyvalent phenol compound is used as a curing agent it is preferably used in a homogeneous system. Examples of preferable polyhydric phenols include polyfunctional novolacs such as phenol-formaldehyde polycondensates, cresol-formaldehyde polycondensates, hydroxybenzaldehyde-phenol polycondensates, cresol-naphthol-formaldehyde polycondensates, resorcin-formalin polycondensates and furfural-phenol polycondensates, a-hydroxyphenyl-.omega.-hydropoly(biphenyldimethylene-hyroxyphenylene); bisphenol A, bisphenol F, bisphenol S, thiodiphenol, 4,4'-biphenylphenol and dihydroxynaphthalene, but are not limited thereto.

Mixing ratio of the thermo-curing agent (b) is preferably 0.8 to 3.0 equivalent, more preferably 0.9 to 2.0 equivalent of active hydrogenbased on the epoxy resin (a) in a sealant for liquid crystals of the present invention. The sealant having such amount of the thermo-curing agent (b) is preferable because of having high adhesive strength, high glass transition temperature and sufficient pot life.

The filler (c) to be used in the present invention is not particularly limited as long as it functions as a filler and includes, for example, fused silica, crystalline silica, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, magnesium oxide, zirconium oxide, aluminum hydroxide, magnesium hydroxide, calcium silicate, aluminum silicate, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, asbestos, preferably, fused silica, crystalline silica, silicon nitride, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, aluminum hydroxide, calcium silicate and aluminum silicate, and fused silica, crystalline silica, alumina and talc are more preferable. The above fillers may be used as a mixture of 2 kinds or more. Considering easy formation of a suitable gap upon bonding upper and lower glass substrates each other in manufacturing a liquid crystal cell, average particle diameter of these fillers is preferably not larger than 3 .mu.m.

Considering easiness of gap formation of a liquid crystal cell, adhesive strength to a glass substrate, moisture-resistant reliability and keeping adhesive strength after moisture absorption, the content of the filler (c) to be used in the present invention in a sealant for liquid crystals is usually 5 to 40% by weight, preferably 15 to 25% by weight.

A sealant for liquid crystals of the present invention can contain, as an additional component, a photo-curable resin, a radical-forming photopolymerization initiator, an ion scavenger, an organic solvent and other additives, which will be described below. Therefore, one of preferable compositions of a sealant of the present invention is 5% to 85%, preferably 10% to 50% of the epoxy resin (a) represented by general formula (1)based on the whole sealant, 0.8 to 3.0, preferably 0.9 to 2.0 equivalent of active hydrogen of the thermo-curing agent (b) based on the epoxy resin (a), 5 to 40% by weight, preferably 15 to 25% by weight of the filler (c) based on the whole sealant, and the balance is other components, which is about 0 to 88%.

To apply a sealant for liquid crystals of the present invention to a liquid-crystal dropping technique, a photo-thermo curing system is preferable. The photo-thermo curing system is characterized by that the sealant for liquid crystals sandwiched by substrates is irradiated by light for primary curing, and subsequent heated for secondary curing. Intending to realize a photo-thermo curing system, the sealant for liquid crystals of the present invention may contain (d) a curable resin having (meth)acrylic group(s) and (e) a radical-forming photopolymerization initiator (here, (meth)acrylic means acrylic and/or methacrylic, and the same hereinafter).

The curable resin (d) having a (meth)acrylic group is not particularly limited, and is preferably a (meth)acrylated resin of an epoxy resin having not less than 2 functions. Epoxy resins with not less than two functional groups include, for example, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a thiodiphenol type epoxy resin, a phenol-novolac type epoxy resin, a cresol-novolac type epoxy resin, a bisphenol A-novolac type epoxy resin, a bisphenol F-novolac type epoxy resin, an alicyclic type epoxy resin, an alkyl chain type epoxy resin, a glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin, a hydantoin type epoxy resin, an isocyanurate type epoxy resin, a phenol-novolac type epoxy resin having triphenolmethane skelton, and further diglycidyletherfied compounds of two functional phenols, diglycidyletherfied compounds of two functional alcohols and halogenides or hydrogenated compounds thereof. Among these, a compound having low solubility to liquid crystals, specifically a (meth)acrylate of an aromatic epoxy resin having not less than 2 functions is preferable. The aromatic epoxy is an epoxy resin obtained by reacting an aromatic compound having a reactive hydroxyl group and an epihalohydrin, wherein the aromatic compound having a reactive hydroxyl group is not particularly limited, and includes the aromatic polyvalent alcohol described in the above item on the epoxy resins (a), for example, bisphenols such as bisphenol A, bisphenol F, bisphenol E, bisphenol S, bisphenolfluorene, biscresolfluorene, oxydidiphenol and thiodiphenol; novolacs such as phenol novolac, cresol novolac, bisphenol A novalac, bisphenol F novalac and phenol novolac having triphenolmethane skelton; polyhydric phenols such as catechol, resorcin, hydroquinone and pyrogallol, biphenol and the like. A (meth)acrylate of an aromatic epoxy resin having 2 functions specifically, a (meth)acrylate of a bisphenol-type epoxy resin and a (meth)acrylate of resorcin are more preferable. A (meth)acrylate of (a) an epoxy resin having an alkylene oxide unit is also preferable. The bisphenol-type epoxy resin is preferably an epoxy resin obtained by subjecting a bisphenol-type divalent alcohol (including bisphenol) explained at the item of the above epoxy resin (a) or a divalent alcohol having an aromatic group obtained by reacting the above bisphenol-type divalent alcohol with an alkylene oxide, and the like, to reaction with epichlorohydrin. Specifically, an epoxy resin represented by the following formula (5): G--O--(--R--O--)n-ph-X-ph-(--O--R--)n-O--G (5) (wherein G, R, n, ph and X have each the same meaning as described above) is preferable.

Combined use of a conventionally known epoxy resin other than the above described resins is not also limited in the present invention. For example, a bisphenol F type epoxy resin, an alicyclic epoxy resin, triglycidyl isocyanate, a heterocycle-containing epoxy resin, and a hydrogenated bisphenol A type epoxy resin are included and these epoxy resins may be used together as long as they do not impair characteristics of the present invention. The amount of the above epoxy resin (a) falls in the range of usually 50 to 100% by weight (the same hereinafter), preferably 80 to 100%, more preferably 90 to 100% based on the total amount of epoxy resins in a sealant.

A sealant for liquid crystals of the present invention including a photo-thermo curing agent is preferably such one as contains hydrolyzable chlorine derived from epoxy resins of not higher than 600 ppm, preferably not higher than 300 ppm. The preferable lower limit is as low as possible, for example, not higher than 100 ppm, but usually not higher than about 300 ppm is low enough from the standpoints of technical problems or cost. Such a level of the hydrolyzable chlorine content provides little risk of liquid crystal contamination with chlorine derived from a sealant. The amount of hydrolyzable chlorine can be quantitatively determined, for example, as follows: About 0.5 g of the epoxy resin is first dissolved in 20 ml of dioxane, and after this mixture is refluxed for 30 minutes using 5 ml of 1-N KOH/ethanol solution, the resulting solution is titrated with a 0.01-N silver nitrate solution. The hydrolyzable chlorine derived from epoxy resins comprises above chlorine derived from the epoxy resin (a) and chlorine derived from an epoxy resin used in producing the (meth) acrylate and chlorine derived from other epoxy resins, if used together. The amount of hydrolyzable chlorine here derived from epoxy resins means the total amount of these chlorines.

An epoxy (meth)acrylate used in the present invention is obtained by esterification of the above epoxy resin with (meth)acrylic acid in the presence of a catalyst and a polymerization inhibitor. In the reaction, one kind or not less than 2 kinds of solvents may be added as diluents, including aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; ethers such as 1,4-dioxane and tetrahydrofuran; ketones such as methylethyl ketone and methylisobutyl ketone; glycol derivatives such as butylcellosolve acetate, carbitol acetate, diethyleneglycol dimethylether and propyleneglycol monomethylether acetate; alicyclic hydrocarbons such as cyclohexanone and cyclohexanol; petroleum solvents such as petroleum ether and petroleum naphtha. These dilution solvents, if used, are required to be removed by evaporation under reduced pressure after completion of the reaction, therefore, a solvent having low boiling point and high volatility is preferable, specifically use of such as toluene, methyl ethyl ketone, methyl isobutyl ketone and carbitol acetate is preferable. Use of a catalyst is preferable to promote reaction. The catalyst to be used includes, for example, benzyldimethylamine, triethylamine, benzyltrimethylammonium chloride, triphenylphosphine and triphenylstibine. The use amount thereof is preferably from 0.1 to 10% by weight, particularly preferably from 0.3 to 5% by weight based on the mixture of the reaction raw materials. To prevent polymerization of (meth)acrylic groups themselves during the reaction, use of a polymerization inhibitor is preferable. Polymerization inhibitors include, for example, methoquinone, hydroquinone, methylhydroquinone, phenothiazine and dibutylhydroxytoluene. The use amount thereof is preferably from 0.01 to 1% by weight, particularly preferably from 0.05 to 0.5% by weight based on the mixture of the reaction raw materials. The reaction temperature is usually from 60 to 150.degree. C., particularly preferably from 80 to 120.degree. C. The reaction time is preferably from 5 to 60 hours.

To control reactivity and viscosity, a monomer and/or an oligomer of a (meth)acrylic ester may be used together as a curable resin having a (meth)acrylic group. Such a monomer and an oligomer include, for example, reaction products of dipentaerythritol with (metha)acrylic acid and reaction products of dipentaerythritol caprolactone with (metha)acrylic acid, but are not particularly limited as long as they have low contamination to a liquid crystal.

The radical-forming photopolymerization initiator (e) to be used for a sealant for liquid crystals of the present invention preferably has sensitivity at the vicinity of i-ray (365 nm) that gives comparatively small effects on characteristics of liquid crystals, and is an initiator of low contamination to liquid crystals. The radical-forming photopolymerization initiators which may be used include, for example, benzyldimethyl ketal, 1-hydroxycyclohexylphenyl ketone, diethylthioxanthone, benzophenone, 2-ethylanthraquinone, 2-hydroxy-2-methylpropiophenone, 2-methyl-[4-(methylthio)-phenyl]2-morpholino-1-propane, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 3,6-bis(2-methyl-2-morpholinopropionyl)-9-n-octylcarbazole and 1,7-bis(9-acrydyl)heptane and preferable ones include carbazole type photopolymerization initiators such as 3,6-bis(2-methyl-2-morpholinopropionyl)-9-n-octylcarbazole and acridine type photopolymerization initiators such as 1,7-bis(9-acrydyl)heptane.

Mixing ratio of the radical-forming photopolymerization initiator (e) to the curable resin (d) having a (meth)acrylic group in a sealant for liquid crystals of the present invention is usually from 0.1 to 10 parts by weight, preferably from 0.5 to 3 parts by weight based on 100 parts by weight of the component (d). The radical-forming photopolymerization initiator of less than 0.1 parts by weight gives insufficient photo-curing reaction, while the concentration over 10 parts by weight, such problems tend to arise as contamination to liquid crystals by the initiator and degradation of cured-resin characteristics.

A sealant for liquid crystals of the present invention preferably contains a silane coupling agent (f) to improve adhesive strength thereof. Coupling agents which may be used include, for example, silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-phenyl-.gamma.-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyl-dimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N-(2-(vinylbenzylamino)ethyl)-3-aminopropyltrimethoxysilane hydrochloride, 3-methacryloyloxypropyltrimehoxysilane, 3-chloropropylmethyldimethoxysilane and 3-chloropropyltrimethoxysilane. Two kinds or more of these silane coupling agents may be mixed, and used. Among these, to obtain superior adhesive strength, a silane coupling agent containing an amino group is preferably used. Using a silane coupling agent, a sealant for liquid crystals having improved adhesive strength and superior moisture-resistant reliability is obtained.

A sealant for liquid crystals of the present invention may further contain an ion scavenger (g) if needed. The ion scavenger added adsorbs and fixes inorganic impurity ions in the sealant for liquid crystals and thus reduces elution of inorganic ions to liquid crystals, resulting in effect of preventing specific resistance of the liquid crystals from lowering. The ion scavenger is preferably an inorganic compound with ion capturing capability. Ion-capturing capability here is ability to reduce ionic impurities by capturing phosphate anions, phosphate anions, organic carboxylate anions, halogen anions, alkaline metal cations, alkaline earth metal cations, etc. The ion scavenger which can be used includes, for example, a bismuth oxide-series ion scavenger represented by the general formula: BiO.sub.X(OH).sub.Y(NO.sub.3).sub.Z (wherein X represents a positive number from 0.9 to 1.1; Y represents a positive number from 0.6 to 0.8; and Z represents a positive number from 0.2 to 0.4), an antimony oxide-series ion scavenger, a titanium phosphate-series ion scavenger, a zirconium phosphate-series ion scavenger and a hydrotalcite-series ion scavenger represented by the general formula: Mg.sub.XAl.sub.Y(OH).sub.2X+3Y-2Z(CO.sub.3).sub.Z.mH.sub.2O (wherein, X, Y and Z represent positive numbers satisfying 2X+3Y-2Z.gtoreq.0; and m represents a positive number). These ion scavengers are available on the market by the trade names such as IXE-100 (zirconium phosphate-series ion scavenger, manufactured by Toa Gosei Co., Ltd.), IXE-300 (antimony oxide-series ion scavenger, manufactured by Toa Gosei Co., Ltd.), IXE-400 (titanium phosphate-series ion scavenger, manufactured by Toa Gosei Co., Ltd.), IXE-500 (bismuth oxide-series ion scavenger, manufactured by Toa Gosei Co., Ltd.), IXE-600 (antimony oxide.cndot. bismuth oxide-series ion scavenger, manufactured by Toa Gosei Co., Ltd.), DHT-4A (hydrotalcite-series ion scavenger, manufactured by Kyowa Chemical Industry Co., Ltd.) and Kyoward KW-2000 (hydrotalcite-series ion scavenger, manufactured by Kyowa Chemical Industry Co., Ltd.). These ion scavengers may be used alone or as a mixture of 2 or more kinds thereof. Usually, the ion scavenger is preferably used in ratio of from 0.2 to 20% by weight in a sealant composition for liquid crystals.

A sealant for liquid crystals of the present invention can further be added, as needed, with such additives as an organic solvent, an organic filler, a stress relaxation material, a pigment, a leveling agent and an antifoaming agent.

Ratio of each component of a sealant for liquid crystals of the present invention is not particularly limited, however, the content of each component based on the total amount of the sealant (composition) is preferably from 5 to 80% of the epoxy resin (a) where n in general formula (1) is not 0 (which has an alkylene oxide unit in the structure), from 2 to 20% of the thermo-curing agent (b), from 5 to 50% of the filler (c) having average particle diameter of not larger than 3 .mu.m, from 5 to 80% of the curable resin (d) having a (meth)acrylic group, from 0.1 to 3% of the radical-forming photopolymerization initiator (e), from 0.2 to 20% of the silane coupling agent (f) and from 0.2 to 2% of the ion scavenger (g). A sealant for liquid crystals of the present invention can be produced by dissolving and mixing, for example, the components (a), (d) and (e) at the above ratio, then adding into thus obtained mixture predetermined amounts of the components (b), (c), (f) and (g), and mixing uniformly using a known mixer such as a three-roll mill, a sand mill and a ball mill. To remove impurities after mixing, the mixture may be subjected to filtration treatment, as needed.

A liquid crystal cell of the present invention has the following structure: a pair of substrates, each having predetermined electrodes formed thereon, are placed in opposing positions each other at a predetermined gap, and the peripheral portion thereof is sealed with a sealant for liquid crystals of the present invention, with a liquid crystal being enclosed in the gap. The kind of the liquid crystal to be enclosed is not particularly limited. Here, the substrates are composed of a combination of substrate made of such as glass, quartz, plastic or silicone wherein at least one has light transmitting property. The manufacturing process is, for example, as follows: After spacers (gap-controlling materials) such as glass fibers have been added to the sealant for liquid crystals of the present invention, the sealant for liquid crystals is applied onto one of the pair substrates in bank form using such as a dispenser, and liquid crystal is then dropped inside the bank of the sealant for liquid crystals, and the other glass substrate is superposed thereon under vacuum to adjust the gap. After the gap formation, ultraviolet rays are irradiated to the liquid-crystal sealed portion using an ultraviolet-ray irradiation device so that the corresponding portion is photo-cured. The dose of ultraviolet-ray irradiation is usually from 500 to 6000 mJ/cm.sup.2, preferably, from 1000 to 4000 mJ/cm.sup.2. Thereafter, the cell is cured at temperature of 90 to 130.degree. C. for one to two hours to obtain a liquid crystal display cell of the present invention. With respect to the spacers, for example, glass fiber, silica beads, polymer beads and the like are used. Diameter of the spacers is different depending on the purposes, but usually from 2 to 8 .mu.m, preferably from 4 to 7 .mu.m. The approximate use amount thereof is usually from 0.1 to 4 parts by weight, preferably, from 0.5 to 2 parts by weight, more preferably, from 0.9 to 1.5 parts by weight, based on 100 parts by weight of the sealant for liquid crystals of the present invention.

A sealant for liquid crystals of the present invention shows significantly low contamination to liquid crystals throughout the manufacturing processes, excellent coating workability and bonding property to a substrate, and high adhesive strength, long workable time (pot life) at room temperature and low-temperature curing property. A liquid crystal cell of the present invention, thus obtained, is free from display defect caused by liquid crystal contamination, and exhibits high adhesive property and superior moisture-resistant reliability.

EXAMPLES

The present invention will be explained in further detail by means of the following Examples, however, the present invention should not be limited thereto.

Synthesis Example 1

Synthesis of an 4,4'-Substituted EO-Added Bis-S-Epoxy Resin (Epoxy Resin A)

Into a flask equipped with a thermometer, a dropping funnel, a condenser and a stirrer, 169 parts of 4,4'-bis(2-hydroxyethyloxy)diphenyl sulfone (trade name: SEO-2; manufactured by Nicca Chemical CO., Ltd., melting point: 183.degree.