Sealant Sheet

Abstract

Provided is a polysulfide-based sealant in which the generation and growth of bubbles are inhibited and which can give shaped objects (cured objects) having high reliability. This sealant is a sealant sheet having a sheet shape and comprising a polysulfide polymer (A), a thiol compound (B) having two or more thiol groups in the molecule, an allyl compound (C) having two or more allyl groups in the molecule, and a photo-radical generator (D).

Description

[Technical Field]

[0001] The present invention relates to a sheet-shaped sealant, i.e., a sealant sheet. This application claims priority to Japanese Patent Application No. 2021-56892, filed on March 30, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Liquid polysulfide polymers contain -SS- bonds in their molecules, and by curing them, they can form rubber-like cured products that have excellent resistance (oil resistance) to oils such as jet fuel and hydraulic oil. For this reason, liquid polysulfide polymers are used as raw materials for sealants used in, for example, aircraft. Patent documents 1 to 3 are cited as technical documents related to liquid polysulfide polymers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2015-517012 [Patent Document 2] Japanese Patent Publication No. 2018-506543 [Patent Document 3] Japanese Patent Publication No. 2019-521223 Summary of the Invention [Problem to be solved by the invention]

[0004] The application of a sealant using a liquid polysulfide polymer is generally carried out by mixing a liquid A containing the liquid polysulfide polymer with a liquid B containing a curing agent for the polysulfide polymer just before application to prepare a liquid sealant, applying the liquid sealant to an object, and then curing the liquid sealant on the object. A strong oxidizing agent such as dichromic acid is often used as the curing agent because it allows the curing reaction to proceed easily at room temperature.

[0005] During the curing reaction of such liquid sealants, bubbles may form inside the sealant due to outgassing caused by the curing reaction. These bubbles grow inside the sealant and, in some cases, the curing reaction continues as they are, resulting in bubbles remaining in the cured product. The presence of bubbles remaining inside the sealant may reduce the reliability of the cured sealant, and is a concern from the perspective of reducing sealing quality, etc.

[0006] In view of the above circumstances, an object of the present invention is to provide a polysulfide sealant that can suppress the generation and growth of bubbles and thereby produce a highly reliable molded product (cured product). [Means for solving the problem]

[0007] To achieve the above object, this specification provides a sealant sheet molded into a sheet shape. The sealant sheet has a degree of viscoelasticity (i.e., a hardness and significantly lower fluidity than a liquid) that allows it to stably maintain its sheet shape, making it easy to suppress the generation and growth of bubbles within the sealant sheet. In one embodiment, the sealant sheet disclosed herein comprises a polysulfide polymer (A), a thiol compound (B) having two or more thiol groups in one molecule, an allyl compound (C) having two or more allyl groups in one molecule, and a photoradical generator (D).

[0008] The sealant sheet having the above configuration can be cured at the desired location through a radical addition reaction (thiol-ene reaction) between thiol groups and allyl groups to improve its strength. The sealant sheet before curing has a suitable elasticity sufficient to stably maintain its sheet shape. Therefore, even if outgassing occurs due to the radical addition reaction, the generation and growth of bubbles within the sealant sheet can be suppressed. Therefore, the resulting cured sealant product tends to contain no bubbles, or if it does contain bubbles, the bubble size is suppressed. In particular, since the photoradical generator (D) is thought to be a potential source of outgassing, applying the technology of the present invention to systems containing the photoradical generator (D) is meaningful.

[0009] Furthermore, the resulting cured sealant can exhibit excellent oil resistance due to the polysulfide structure. Furthermore, since the thickness of the cured product can be controlled by the thickness of the sealant sheet used, there is no need to adjust the coating thickness during application, as is the case with liquid sealants. Therefore, the sealant sheet allows for easy and accurate application of polysulfide sealants. Furthermore, since the sealant sheet is configured to promote the addition reaction by generating radicals from the photoradical generator (D) upon light irradiation, it can exhibit good storage stability by being stored in an environment that suppresses radical generation from the photoradical generator (D).

[0010] As the thiol compound (B), one having a thiol equivalent of 45 g / eq or more and 450 g / eq or less can be preferably used, taking into consideration the balance between storage stability before use and curing property during use.

[0011] In a preferred embodiment disclosed herein, the sealant sheet contains at least one allyl compound (C) selected from the group consisting of bifunctional allyl compounds and trifunctional allyl compounds. The inclusion of such an allyl compound (C) facilitates a well-balanced improvement in shelf life before use and curability during use.

[0012] As the photoradical generator (D), for example, at least one selected from the group consisting of alkylphenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, and titanocene compound-based photopolymerization initiators can be preferably used. By using such a photoradical generator (D), a sealant sheet can be suitably realized that has a good balance between good storage stability before use and good curing properties (photoradical curing properties) during use.

[0013] The sealant sheet disclosed herein may contain a filler, which may improve one or both of the strength and elongation of the cured sealant.

[0014] The sealant sheet preferably has a storage modulus of 0.005 MPa or more and 0.8 MPa or less at 25° C. A sealant sheet having a storage modulus in this range easily achieves a good balance between adhesion to an object and sheet shape retention.

[0015] In another embodiment, the sealant sheet disclosed herein is a sealant sheet formed into a sheet shape, comprising a thiol group-containing polysulfide polymer (AB) having two or more thiol groups per molecule, an allyl compound (C) having two or more allyl groups per molecule, and a photoradical generator (D). A sealant sheet of this configuration can also be cured in a desired location through a radical addition reaction between the thiol group and the allyl group, thereby improving its strength. The sealant sheet before curing has a suitable elasticity that allows it to stably maintain its sheet shape, thereby suppressing the generation and growth of bubbles within the sealant sheet, even if outgassing occurs due to the radical addition reaction. Therefore, the resulting cured sealant product tends to be bubble-free, or if it does contain bubbles, the bubble size is suppressed.

[0016] The sealant sheet before use (i.e., before placement at a desired location) may be in the form of a sealant sheet with a release liner, comprising the sealant sheet and a release liner having a release surface abutting at least one surface of the sealant sheet. A sealant sheet in this form is preferred from the viewpoints of the shelf life of the sealant sheet and ease of handling during transportation, processing, placement at a desired location, etc.

[0017] This specification also provides a sealant cured product that is a cured product of a polysulfide-based sealant. The cured product includes a disulfide structure, a structure derived from a radical addition reaction between a thiol group and an allyl group, and a compound derived from a photoradical generator. Such a sealant cured product is preferable because it can be formed by promoting the radical addition reaction between a thiol group and an allyl group (thiol-ene reaction) using radicals generated from the photoradical generator as a trigger.

[0018] In addition, any suitable combination of the above elements may also be included in the scope of the invention for which patent protection is sought through this patent application. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an example of the configuration of a sealant sheet. [Figure 2] FIG. 10 is a cross-sectional view schematically showing another example of the configuration of the sealant sheet. DETAILED DESCRIPTION OF THE INVENTION

[0020] Preferred embodiments of the present invention are described below. Matters necessary for carrying out the present invention other than those specifically mentioned in this specification can be understood by those skilled in the art based on the teachings for carrying out the invention described in this specification and the common general technical knowledge at the time of filing. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. Furthermore, in the following drawings, components and parts that perform the same function may be denoted by the same reference numerals, and redundant explanations may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic for the purpose of clearly explaining the present invention, and do not necessarily accurately represent the size or scale of the actual product provided.

[0021] <Sealant sheet> The sealant sheet disclosed herein is preformed into a sheet shape and can be placed in the area to be sealed in this sheet form. In this respect, the sealant sheet is clearly distinguished from liquid sealants that are applied to the area to be sealed in liquid form (for example, a liquid sealant prepared by mixing Liquid A containing a liquid polysulfide polymer with Liquid B containing a curing agent for the polysulfide polymer immediately before application). Furthermore, the sealant sheet disclosed herein can be cured using an addition reaction between a thiol group and an allyl group (thiol-ene reaction). In terms of having such curability, the sealant sheet disclosed herein is clearly distinguished from a cured sealant (cured sealant). The sealant sheet disclosed herein can be understood as a semi-cured sealant sheet that can be further cured after being placed in the area to be sealed.

[0022] An example of the configuration of the sealant sheet disclosed herein is shown in FIGS. 1, one surface (first surface) 21A and the other surface (second surface) 21B are protected by release liners 31 and 32, respectively, with the release surface facing at least the sealant sheet 21. The sealant sheet 21 in this form can be understood as a component of a sealant sheet with release liner 100, which includes the sealant sheet 21 and the release liners 31 and 32. 2 has one surface 21A protected by a release liner 31 having release surfaces on both sides, and when rolled up, the other surface 21B of the sealant sheet 21 abuts against the back surface of the release liner 31, so that surface 21B is also protected by the release liner 31. A sealant sheet 21 of this type can be understood as a component of a sealant sheet with a release liner 200 that includes the sealant sheet 21 and the release liner 31.

[0023] The sealant sheet disclosed herein preferably has a shape retention sufficient to stably maintain the sheet shape at room temperature (e.g., about 25°C). Shape retention can also be understood as resistance to plastic deformation such as flow. The storage modulus of the sealant sheet at 25°C (hereinafter simply referred to as "storage modulus") may be, for example, 0.005 MPa or more (e.g., greater than 0.005 MPa), preferably greater than 0.01 MPa. A higher storage modulus of the sealant sheet tends to improve the handleability and processability (e.g., cuttability, anti-blocking properties, reworkability, etc.) of the sealant sheet. In some embodiments, the storage modulus of the sealant sheet may be, for example, 0.05 MPa or more, 0.1 MPa or more, or 0.2 MPa or more. The upper limit of the storage modulus is not particularly limited. In some embodiments, the storage modulus of the sealant sheet may be, for example, 2 MPa or less, 1 MPa or less, 0.8 MPa or less, 0.6 MPa or less, 0.5 MPa or less, 0.4 MPa or less, or 0.3 MPa or less. A lower storage modulus of the sealant sheet tends to improve its ability to conform to the surface shape of the area to be sealed.

[0024] The storage modulus is measured using a viscoelasticity tester under conditions of a frequency of 1 Hz and a strain of 0.5%. The viscoelasticity tester may be an "ARES G2" model manufactured by TA Instruments Japan or an equivalent. More specifically, the storage modulus is measured by the method described in the Examples below. Furthermore, in this specification, unless otherwise specified, the storage modulus of a sealant sheet refers to the storage modulus of the sealant sheet before curing, and is to be distinguished from the storage modulus of the sealant sheet after curing (cured sealant). In this specification, the storage modulus of a sealant sheet typically refers to the storage modulus of the sealant sheet before use, i.e., before placement at the location to be sealed by application or the like.

[0025] The thickness of the sealant sheet is not particularly limited and can be selected depending on the desired thickness of the cured sealant. From the viewpoint of sealing reliability, etc., in some embodiments, the thickness of the sealant sheet may be, for example, 0.01 mm or more, 0.03 mm or more, 0.05 mm or more, 0.1 mm or more, or 0.15 mm or more. The sealant sheet disclosed herein may also be suitably implemented in an embodiment having a thickness of, for example, more than 0.3 mm, more than 0.5 mm, more than 1 mm, or more than 1.5 mm. Furthermore, in some embodiments, the thickness of the sealant sheet may be, for example, 10 mm or less, 5 mm or less, 3 mm or less, 2 mm or less, 1 mm or less, 0.5 mm or less, or 0.3 mm or less. As the thickness of the sealant sheet decreases, the photocurability tends to improve. Reducing the thickness of the sealant sheet can be advantageous from the viewpoint of its ability to conform to the surface shape of the area to be sealed and its weight reduction.

[0026] <Polysulfide polymer (A)> The sealant sheet disclosed herein contains a polysulfide polymer (A). The polysulfide polymer (A) is a polymer having a repeating unit containing a disulfide structure represented by -SS-, and contributes to improving the oil resistance of a cured product formed from the sealant sheet.

[0027] The number of disulfide structures contained in one molecule of the polysulfide polymer (A) may be one or two or more. From the viewpoint of the oil resistance of the cured product, a polysulfide polymer (A) containing an average of three or more disulfide structures per molecule can be preferably used. The average number of disulfide structures per molecule of the polysulfide polymer (A) (hereinafter also referred to as the average number of disulfide groups) may be, for example, 5 or more, 10 or more, 15 or more, or 20 or more. There is no particular upper limit to the average number of disulfide groups, but from the viewpoint of ease of production of the sealant sheet (e.g., ease of forming into a sheet shape), it may be, for example, 100 or less, 70 or less, or 50 or less.

[0028] The disulfide structure is preferably contained in the main chain of the polysulfide polymer (A), since the main chain contains a disulfide structure, a cured product with good elongation tends to be formed.

[0029] In some embodiments, the polysulfide polymer (A) preferably contains a repeating unit represented by the following general formula (1): -R 1 -OR 2 -OR 3 -SS- (1) Here, in general formula (1), R 1 , R 2 , R 3are each independently an alkylene group having 1 to 4 carbon atoms, preferably an alkylene group having 1 to 3 carbon atoms, and more preferably an alkylene group having 1 to 2 carbon atoms. The repeating unit (1) has a structure in which an ether structure and a disulfide structure are linked together. A polysulfide polymer (A) having such a repeating unit (1) tends to form a cured product having excellent oil resistance and flexibility. The average number of the repeating units (1) contained in one molecule of the polysulfide polymer (A) may be, for example, 5 or more, 10 or more, 15 or more, or 20 or more. The average number may be, for example, 100 or less, 70 or less, or 50 or less. The polysulfide polymer (A) may have only one region in which the repeating units (1) are continuous, or two or more regions in one molecule.

[0030] In some embodiments, the polysulfide polymer (A) may include at least one of a structure represented by the following general formula (2a) and a structure represented by the following general formula (2b). -CH2-S-CH2CHOH-R' (2a) -CH2-S-CH(CH2OH)-R' (2b) Here, R' in general formulas (2a) and (2b) represents an organic group having at least one epoxy group (e.g., about 1 to 5). The structures of general formulas (2a) and (2b) can be formed, for example, by an addition reaction between a thiol having a structural moiety represented by -CH2-SH and an epoxy compound having a substituent R' on the epoxy ring. The number of structures represented by general formula (2a) or (2b) (when both structures represented by general formula (2a) and general formula (2b) are included, the total number) may be, for example, 1.1 or more, 1.3 or more, 1.5 or more, 1.8 or more, 2.0 or more, or even more than 2.0, as an average value per molecule of polysulfide polymer (A). Furthermore, the average value may be, for example, 15 or less, 10 or less, 7.0 or less, or 5.0 or less.

[0031] The structure represented by the general formula (2a) or (2b) can be formed by an addition reaction between a thiol group and an epoxy group. The polysulfide polymer (A) containing the structure represented by the general formula (2a) or (2b) can be, for example, a reaction product or a modified product of a thiol-containing polysulfide having a disulfide structure and a thiol group in one molecule with an epoxy compound having two or more epoxy groups in one molecule.

[0032] The weight-average molecular weight (Mw) of the thiol group-containing polysulfide used as a precursor of the polysulfide polymer (A) is not particularly limited and may be, for example, 500 or more, 800 or more, 1000 or more, more than 1000, or more than 2000. Thiol group-containing polysulfides with a higher Mw tend to produce sealant sheets that provide cured products with better elongation. In some embodiments, the Mw of the thiol group-containing polysulfide may be, for example, more than 2500, more than 3000, or more than 3500. Furthermore, the Mw of the thiol group-containing polysulfide may be, for example, 30,000 or less, or 10,000 or less. From the viewpoint of handleability and reactivity with the epoxy compound, in some embodiments, the Mw of the thiol group-containing polysulfide may be, for example, less than 9,000, less than 8,000, less than 7,500, less than 7,000, or less than 6,500.

[0033] In this specification, the Mw of polymers such as thiol group-containing polysulfide, epoxy group-containing polysulfide, and polysulfide polymer (A) described below can be determined in terms of polyethylene glycol by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the mobile phase. Alternatively, nominal values ​​listed in catalogs, literature, etc. may be used.

[0034] The thiol group-containing polysulfide preferably contains the disulfide structure in its main chain. A sealant sheet containing a polysulfide polymer (A), which is a reaction product or modified product of a thiol group-containing polysulfide containing a disulfide structure in its main chain with an epoxy compound having two or more epoxy groups per molecule, tends to form a cured product with good elongation. The number of disulfide structures contained in one molecule of the thiol group-containing polysulfide, expressed as the average value (average number of disulfide groups) of the entire thiol group-containing polysulfide used, may be, for example, 3 or more, 5 or more, 10 or more, 15 or more, or 20 or more. The upper limit of the average number of disulfide groups is not particularly limited, but may be, for example, 100 or less, 70 or less, or 50 or less, from the viewpoint of ease of production of the sealant sheet (e.g., ease of forming into a sheet shape).

[0035] The number of thiol groups contained in the thiol group-containing polysulfide as a precursor of the polysulfide polymer (A) may be one or two or more per molecule of the thiol group-containing polysulfide. From the viewpoint of easily realizing a sealant sheet suitable for improving the strength of the cured product and shortening the curing time, a thiol group-containing polysulfide having an average number of thiol groups per molecule greater than one is preferred. The average number of thiol groups per molecule of the thiol group-containing polysulfide used (average number of thiol groups) may be, for example, 1.1 or more, 1.3 or more, 1.5 or more, 1.8 or more, 2 or more, or even more than 2. The upper limit of the average number of thiol groups is not particularly limited, but from the viewpoint of flexibility of the cured product, it may be, for example, 15 or less, 10 or less, 7 or less, or 5 or less. A polysulfide having an average number of thiol groups of two or more may also be considered as a thiol compound (B) having two or more thiol groups per molecule.

[0036] The thiol group is preferably located at the end of the thiol group-containing polysulfide. By reacting such a thiol group-containing polysulfide with an epoxy compound having two or more epoxy groups per molecule, an epoxy group-containing polysulfide polymer having epoxy groups at its terminals can be suitably formed. The thiol group-containing polysulfide used may have a thiol group at one end of the main chain, at both ends of the main chain, or at a site other than the end of the main chain, or may be a mixture of any combination thereof. The use of a thiol group-containing polysulfide having thiol groups at both ends of the main chain, i.e., a double-ended thiol polysulfide, is particularly preferred. A sealant sheet containing a polysulfide polymer (A) synthesized using a double-ended thiol polysulfide tends to form a cured product that exhibits a good balance between strength and elongation. In some embodiments, the proportion of both-terminated thiol polysulfides in the total thiol group-containing polysulfides used may be, for example, greater than 50%, greater than 70%, greater than 90%, greater than 95%, greater than 98%, or even substantially 100% by weight.

[0037] The both-end thiol polysulfide is preferably represented by the following general formula (3). HS-(R 1 -OR 2 -OR 3 -SS) n -R 1 -OR 2 -OR 3 -SH (3)

[0038] In general formula (3), R 1 , R 2 , R 3are each independently an alkylene group having 1 to 4 carbon atoms, preferably an alkylene group having 1 to 3 carbon atoms, and more preferably an alkylene group having 1 to 2 carbon atoms. n in general formula (3) can be an integer selected so that the formula weight of the compound of general formula (3) is, for example, from 500 to 10,000, or from 800 to less than 9,000, or from 1,000 to less than 8,000, or from more than 1,000 to less than 8,000, or more than 2,000 to less than 7,500.

[0039] In some embodiments, the compound represented by general formula (3) is, for example, R 1 is C2H4 and R 2 is CH2 and R 3 In this embodiment, n in the general formula (3) may be, for example, 3 to 70, 5 to 60, 7 to 50, or 10 to 50.

[0040] (Epoxy group-containing polysulfide polymer (AA)) In a preferred embodiment of the technology disclosed herein, the sealant sheet comprises an epoxy group-containing polysulfide polymer (AA) having two or more epoxy groups per molecule as the polysulfide polymer (A), a thiol compound (B) having two or more thiol groups per molecule, an allyl compound (C) having two or more allyl groups per molecule, and a photoradical generator (D). The sealant sheet of this embodiment may or may not further comprise a polysulfide polymer (A) that does not fall under the category of the epoxy group-containing polysulfide polymer (AA).

[0041] The average number of epoxy groups per molecule of the epoxy group-containing polysulfide polymer (AA) (hereinafter also referred to as the average number of epoxy groups) can be, for example, about 2 or more and 20 or less. From the viewpoint of flexibility of the cured product, the average number of epoxy groups may be, for example, 15 or less, 10 or less, 7 or less, or 5 or less. In some embodiments, the average number of epoxy groups may be 4 or less, or 3 or less. Furthermore, the average number of epoxy groups is typically 2 or more, and from the viewpoint of curability and strength of the cured product, it may be more than 2 or 2.5 or more. In some embodiments, the average number of epoxy groups may be, for example, 3 or more, or 4 or more.

[0042] The epoxy group contained in the epoxy group-containing polysulfide polymer (AA) is preferably located at the terminal of the epoxy group-containing polysulfide polymer (AA). Such an epoxy group-containing polysulfide polymer (AA) tends to form a cured product with good elongation. The sealant sheet disclosed herein may contain, as the polysulfide polymer (A), an epoxy group-containing polysulfide polymer (AA) having two or more epoxy groups at one end of the main chain, an epoxy group-containing polysulfide polymer (AA) having one or two or more epoxy groups at each end of the main chain, or both. The epoxy group-containing polysulfide polymer (AA) having an epoxy group at one end of the main chain may have a functional group other than the epoxy group at an end other than the end having the epoxy group. The functional group other than the epoxy group may be, for example, a thiol group, an amino group, a hydroxyl group, etc. The sealant sheet disclosed herein preferably contains at least an epoxy group-containing polysulfide polymer (AA) having epoxy groups at both ends of the main chain. By including an epoxy group-containing polysulfide polymer (AA) having such a structure, a cured product tends to be formed that has a good balance between strength and elongation. For example, an epoxy group-containing polysulfide polymer (AA) having one epoxy group at each end of the main chain can be preferably used.

[0043] The epoxy group-containing polysulfide polymer (AA) can be obtained, for example, by reacting the above-mentioned thiol group-containing polysulfide with an epoxy compound having two or more epoxy groups per molecule so that the amount of epoxy groups is in excess. The epoxy compound may be a bifunctional epoxy compound having two epoxy groups per molecule, or a multifunctional epoxy compound having three or more epoxy groups per molecule. The epoxy compounds may be used alone or in combination of two or more. In view of operability during reaction with the thiol group-containing polysulfide, in some embodiments, an epoxy compound that is liquid at room temperature may be preferably used.

[0044] Examples of bifunctional epoxy compounds include, but are not limited to, bisphenol A epoxy resins, bisphenol F epoxy resins, hydrogenated bisphenol A epoxy resins (i.e., epoxy compounds corresponding to a structure in which the aromatic rings of bisphenol A epoxy resins are converted to cycloalkyl rings by hydrogenation), hydrogenated bisphenol F epoxy resins, biphenyl epoxy resins, aliphatic epoxy resins (e.g., polypropylene glycol epoxy resins), 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and the like.

[0045] Examples of polyfunctional epoxy compounds include, but are not limited to, novolac-type epoxy resins, glycidylamine-type epoxy resins, biphenyl-type epoxy resins, triphenylmethane-type epoxy resins, dicyclopentadiene-type epoxy resins, glycerin-type epoxy resins, trimethylolpropane-type epoxy resins, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and polyglycerol polyglycidyl ether. The number of epoxy groups contained in one molecule of the polyfunctional epoxy compound is at least 3 or more, and may be 4 or more, or 5 or more. The number of epoxy groups contained in one molecule of the polyfunctional epoxy compound is typically 10 or less, and may be 8 or less, or 6 or less.

[0046] In some embodiments, a bifunctional epoxy compound can be preferably used as the epoxy compound. The use of a bifunctional epoxy compound can be advantageous for obtaining a sealant sheet that provides a cured product exhibiting suitable elongation. The bifunctional epoxy compounds can be used alone or in combination of two or more.

[0047] In some embodiments, the bifunctional epoxy compound may preferably be an epoxy compound containing a five- or higher-membered carbon ring structure in the molecule. A sealant sheet containing a bifunctional epoxy compound with such a structure tends to form a cured product with high strength and good elongation. The five- or higher-membered carbon ring structure may be, for example, a benzene ring, a naphthalene ring, or a cyclohexyl ring. Examples of epoxy compounds containing such a carbon ring structure include bisphenol A epoxy resins, bisphenol F epoxy resins, hydrogenated bisphenol A epoxy resins, hydrogenated bisphenol F epoxy resins, and biphenyl epoxy resins. In a preferred embodiment, a bisphenol F epoxy resin may be used as the bifunctional epoxy compound.

[0048] As the epoxy compound, one or more polyfunctional epoxy compounds can be used in combination with a difunctional epoxy compound or in place of a difunctional epoxy resin. The use of a polyfunctional epoxy compound can improve the strength of the cured product. The use of a bifunctional epoxy compound and a polyfunctional epoxy compound in combination can realize a sealant sheet that gives a cured product that exhibits both high levels of strength and elongation.

[0049] In some embodiments, the polyfunctional epoxy compound may be a polyfunctional epoxy compound having a repeating unit containing an epoxy group (i.e., a polymer type), and for example, a novolac epoxy resin may be preferably used. Examples of the novolac epoxy resin include phenol novolac epoxy resin and o-cresol novolac epoxy resin. The use of a novolac epoxy resin may be advantageous for obtaining a sealant sheet that provides a cured product with high strength and good elongation. The use of a novolac epoxy resin with a lower molecular weight tends to improve the elongation of the cured product. For example, a phenol novolac epoxy resin that is liquid at room temperature may be preferably used.

[0050] In the reaction between the thiol group-containing polysulfide and the epoxy compound having two or more epoxy groups per molecule, any suitable catalyst may be used as long as it does not significantly impair the effects obtained by the technology disclosed herein. For example, known basic catalysts such as 2,4,6-triaminomethylphenol, triethylamine, and 1,8-diazabicyclo[5.4.0]undec-7-ene may be appropriately selected and used.

[0051] When a basic catalyst is used in the reaction between a thiol group-containing polysulfide and an epoxy compound having two or more epoxy groups per molecule, the amount used is not particularly limited and can be set so that the catalytic function is properly exhibited. In some embodiments, the amount of the basic catalyst used can be, for example, 1 part by weight or less, typically 0.5 parts by weight or less, per 100 parts by weight of the total amount of the thiol group-containing polysulfide and the epoxy compound having two or more epoxy groups per molecule, and may be 0.2 parts by weight or less, 0.1 parts by weight or less, or even 0.08 parts by weight or less. From the viewpoint of improving the shelf life of the sealant sheet, it is advantageous not to use too much of the basic catalyst. From this viewpoint, the amount of the basic catalyst used per 100 parts by weight of the total amount can be, for example, 0.07 parts by weight or less, 0.05 parts by weight or less, 0.03 parts by weight or less, or 0.02 parts by weight or less. The lower limit of the amount of the basic catalyst used relative to 100 parts by weight of the total amount is not particularly limited, and can be, for example, 0.001 part by weight or more, or may be 0.005 part by weight or more.

[0052] The reaction can be carried out by mixing a thiol group-containing polysulfide, an epoxy compound having two or more epoxy groups per molecule, and an optional catalyst in a suitable reaction vessel. In some preferred embodiments, the thiol group-containing polysulfide, a bifunctional epoxy compound, a polyfunctional epoxy compound, and a catalyst (e.g., a basic catalyst) are mixed in a suitable reaction vessel. The method of supplying each material to the reaction vessel and the order of mixing are not particularly limited and can be selected so as to form an appropriate reaction product. The reaction conditions can be appropriately set as long as they do not significantly impair the effects obtained by the technology disclosed herein. In some embodiments, the reaction can be carried out at a reaction temperature of, for example, 0°C to 120°C, preferably 5°C to 120°C, and more preferably 10°C to 120°C. In consideration of reaction controllability and reaction efficiency, in some embodiments, the reaction temperature can be, for example, 20°C to 100°C, 30°C to 100°C, 40°C to 100°C, or 60°C to 100°C. The reaction time is not particularly limited and can be selected within the range of, for example, 10 minutes to 720 hours (preferably 1 hour to 240 hours).

[0053] In some embodiments, the reaction can be carried out by sequentially performing a first heating step at a temperature of, for example, 60°C to 120°C (preferably 70°C to 110°C) and a second heating step at a temperature of 40°C to 80°C (preferably 50°C to 70°C). By performing the heating steps stepwise in this manner, the elastic modulus of the polysulfide reaction product can be prevented from becoming too high, and the mixing (e.g., kneading) step of the reaction product with additional components such as a filler can be carried out efficiently. The second heating step is preferably carried out at a temperature lower than that of the first heating step. The heating time in the first heating step can be, for example, 10 minutes or more, and is usually suitably 30 minutes or more, and may be 1 hour or more. In a preferred embodiment, the heating time in the first heating step can be selected within a range of, for example, 10 minutes to 24 hours (preferably 30 minutes to 12 hours, more preferably 1 hour to 6 hours). The heating time in the second heating step can be, for example, 3 hours or more, and is usually suitably 6 hours or more, and may be 24 hours or more. In a preferred embodiment, the heating time in the second heating step can be selected, for example, from the range of 3 hours to 720 hours (preferably 48 hours to 500 hours, more preferably 72 hours to 300 hours). The heating time in the second heating step is preferably longer than the heating time in the first heating step. The heating step may be carried out stepwise in three or more stages.

[0054] In synthesizing the epoxy group-containing polysulfide polymer (AA) by the above reaction, the ratio of the thiol group-containing polysulfide to the epoxy compound used can be set so that the ratio of the total number of epoxy groups contained in the epoxy compound to the total number of thiol groups contained in the thiol group-containing polysulfide, i.e., the epoxy group / thiol group equivalent ratio (hereinafter also referred to as the epoxy / thiol ratio), is greater than 1. In some embodiments, the epoxy / thiol ratio can be, for example, 1.05 or greater, or even 1.1 or greater. From the viewpoint of improving the strength of the cured product, in some embodiments, the epoxy / thiol ratio can be, for example, greater than 1.2, greater than 1.4, greater than 1.5, or greater than 1.7. Furthermore, the epoxy / thiol ratio can be, for example, less than 7.0, less than 5.0, less than 4.5, or less than 4.0. In some embodiments, from the viewpoint of improving the elongation of the cured product, the epoxy / thiol ratio may be, for example, less than 3.5, less than 3.2, less than 3.0, less than 2.5, less than 2.0, or less than 1.8.

[0055] In the synthesis of the epoxy group-containing polysulfide polymer (AA) by the above reaction, the amount of the epoxy compound having two or more epoxy groups per molecule used is not particularly limited. The amount of the epoxy compound used can be set, for example, so as to achieve any of the above-mentioned epoxy / thiol ratios. In some embodiments, the amount of the epoxy compound used can be, for example, 1 part by weight or more, typically 3 parts by weight or more, or even 5 parts by weight or more, or even 7 parts by weight or more, per 100 parts by weight of the thiol group-containing polysulfide. Furthermore, the amount of the epoxy compound used can be, for example, 50 parts by weight or less, typically 30 parts by weight or less, or even 20 parts by weight or less, or even 15 parts by weight or less, per 100 parts by weight of the thiol group-containing polysulfide.

[0056] (Thiol group-containing polysulfide polymer (AB)) In a preferred embodiment, the sealant sheet disclosed herein comprises a thiol group-containing polysulfide polymer (AB) having two or more thiol groups per molecule as the polysulfide polymer (A), an allyl compound (C) having two or more allyl groups per molecule, and a photoradical generator (D). The sealant sheet of this embodiment may or may not further comprise a polysulfide polymer (A) that does not fall under the category of the thiol group-containing polysulfide polymer (AB). Furthermore, the sealant sheet of the above embodiment may or may not further comprise a thiol compound (B) that does not fall under the category of the thiol group-containing polysulfide polymer (AB). When the thiol compound (B) is contained, the sealant sheet disclosed herein contains a thiol group-containing polysulfide polymer (AB) having two or more thiol groups in one molecule as the polysulfide polymer (A), a thiol compound (B) having two or more thiol groups in one molecule, an allyl compound (C) having two or more allyl groups in one molecule, and a photoradical generator (D).

[0057] The average number of thiol groups in the thiol group-containing polysulfide polymer (AB) is typically 2 or more, and may be more than 2. There is no particular upper limit on the average number of thiol groups, but from the viewpoint of flexibility of the cured product, it is usually appropriate that the number is 10 or less, and may also be 7 or less, 5 or less, 4 or less, 3 or less, 2.8 or less, or 2.4 or less. The thiol groups contained in the thiol group-containing polysulfide polymer (AB) are preferably located at the terminals of the thiol group-containing polysulfide polymer (AB). Such a thiol group-containing polysulfide polymer (AB) tends to form a cured product with good elongation. A thiol group-containing polysulfide polymer (AB) having one or more thiol groups at each end of the main chain is preferred, and a thiol group-containing polysulfide polymer (AB) having one thiol group at each end of the main chain is more preferred. By including a thiol group-containing polysulfide polymer (AB) with such a structure, a cured product tends to be formed that has a good balance between strength and elongation.

[0058] The thiol group-containing polysulfide polymer (AB) can be, for example, a product obtained by reacting the above-mentioned epoxy group-containing polysulfide polymer (AA) with a thiol compound having two or more thiol groups per molecule so that the amount of thiol groups is in excess. The thiol compound may be a bifunctional thiol compound having two thiol groups per molecule, or a polyfunctional thiol compound having three or more thiol groups per molecule. The thiol compounds can be used alone or in combination. From the viewpoint of obtaining a sealant sheet that gives a cured product exhibiting suitable elongation, bifunctional thiol compounds are preferably used. For example, of the thiol compounds reacted with the epoxy groups of the epoxy group-containing polysulfide polymer (AA), 50 wt % or more, 70 wt % or more, or 90 wt % or more can be bifunctional thiol compounds. The thiol compound may be used alone.

[0059] The thiol compound to be reacted with the epoxy group-containing polysulfide polymer (AA) can be, for example, one or more selected from materials that can be used as the thiol compound (B) described below. The reaction between the epoxy group-containing polysulfide polymer (AA) and the thiol compound can be carried out in the same manner as the reaction between the thiol group-containing polysulfide and the epoxy compound described above.

[0060] In synthesizing the thiol group-containing polysulfide polymer (AB) by the above reaction, the ratio of the epoxy group-containing polysulfide to the thiol compound used can be set so that the ratio of the total number of thiol groups contained in the thiol compound to the total number of epoxy groups contained in the epoxy group-containing polysulfide, i.e., the epoxy / thiol ratio, is less than 1. From the viewpoint of improving the strength of the cured product, in some embodiments, the epoxy / thiol ratio can be, for example, 0.95 or less, or may be 0.9 or less, or may be 0.85 or less. Furthermore, the epoxy / thiol ratio can be, for example, 0.1 or more, and is usually suitably 0.2 or more. In some embodiments, from the viewpoint of improving the elongation of the cured product, the epoxy / thiol ratio can be, for example, 0.3 or more, or 0.5 or more, or 0.6 or more, or 0.7 or more.

[0061] In the synthesis of the thiol group-containing polysulfide polymer (AB) by the above reaction, the amount of the thiol compound having two or more thiol groups per molecule used is not particularly limited. The amount of the thiol compound used can be set, for example, so as to achieve any of the above-mentioned epoxy / thiol ratios. In some embodiments, the amount of the thiol compound used can be, for example, 1 part by weight or more, typically 3 parts by weight or more, or even 5 parts by weight or more, or even 7 parts by weight or more, per 100 parts by weight of the epoxy group-containing polysulfide. Furthermore, the amount of the thiol compound used can be, for example, 50 parts by weight or less, typically 30 parts by weight or less, or even 20 parts by weight or less, or even 15 parts by weight or less, per 100 parts by weight of the epoxy group-containing polysulfide.

[0062] Furthermore, as the thiol group-containing polysulfide polymer (AB), for example, the thiol group-containing polysulfide (preferably, a polysulfide having thiols at both ends) described above as a material that can be used as a precursor of the polysulfide polymer (A) may be used.

[0063] <Thiol Compound (B)> The thiol compound (B) contained in the sealant sheet disclosed herein can be any compound having two or more thiol groups in one molecule, without any particular limitation. For example, trimethylolpropane tris(3-mercaptopropionate)), pentaerythritol tetrakis(thiopropionate), ethylene glycol bis(thioglycolate), 1,4-butanediol bis(thioglycolate), trimethylolpropane tris(thioglycolate), pentaerythritol tetrakis(thioglycolate), di(2-mercaptoethyl)ether, 1,4-butanedithiol, 1,5-dimercapto-3-thiapentane, 1,8-dimercapto-3,6 -dioxaoctane (also known as 3,6-dioxa-1,8-octanedithiol), 1,3,5-trimercaptomethylbenzene, 4,4'-thiodibenzenethiol, 1,3,5-trimercaptomethyl-2,4,6-trimethylbenzene, 2,4,6-trimercapto-s-triazine, 2-dibutylamino-4,6-dimercapto-s-triazine, pentaerythritol tetrakis(3-mercaptopropionate), dipentaerythritol hexa-3-mercaptopropionate, and the like, but are not limited to these.

[0064] Commercially available thiol compounds (B) include, but are not limited to, jER Mate QX11, QX12, jER Cure (registered trademark) QX30, QX40, QX60, QX900, and Capcure CP3-800 manufactured by Mitsubishi Chemical Corporation; OTG, EGTG, TMTG, PETG, 3-MPA, TMTP, and PETP manufactured by Yodo Chemical Co., Ltd.; TEMPIC, TMMP, PEMP, PEMP-II-20P, and DPMP manufactured by Sakai Chemical Co., Ltd.; KarenzMT (registered trademark) PE1, KarenzMT (registered trademark) BD1, KarenzMT (registered trademark) NR1, KarenzMT (registered trademark) TPMB, and TEMB manufactured by Showa Denko K.K. Each of these compounds may be used alone, or two or more may be used in combination.

[0065] The average number of thiol groups in the thiol compound (B) contained in the sealant sheet can be, for example, about 2 or more and 10 or less. From the viewpoint of flexibility of the cured product, the average number of thiol groups may be, for example, 7 or less, 5 or less, 4 or less, or even less than 4. In some embodiments, the average number of thiol groups may be 3 or less, 2.5 or less, or 2.2 or less. Only one or two or more bifunctional thiol compounds may be used as the thiol compound (B). This configuration makes it easier to obtain a sealant sheet that gives a cured product exhibiting suitable elongation.

[0066] As the thiol compound (B), any of compounds having a primary thiol group (hereinafter also referred to as a primary thiol compound), a compound having a secondary thiol group (secondary thiol compound), and a compound having a tertiary thiol group (tertiary thiol compound) can be used. From the viewpoint of curing property during use of the sealant sheet, a primary thiol compound can be preferably used. Furthermore, from the viewpoint of storage stability of the sealant sheet before use, a secondary or higher thiol compound (i.e., a secondary thiol compound and / or a tertiary thiol compound) can be preferably used. Note that, hereinafter, a thiol compound having two primary thiol groups in one molecule may be referred to as a primary bifunctional thiol compound, and a thiol compound having two secondary thiol groups in one molecule may be referred to as a secondary bifunctional thiol compound.

[0067] In some embodiments, a primary thiol compound and a secondary or higher thiol compound (e.g., a secondary thiol compound) can be used in combination as the thiol compound (B). According to such an embodiment, the shelf life of the sealant sheet before use and the curing property during use can be favorably achieved at the same time. The weight ratio of the primary thiol compound to the total weight of the primary thiol compound and the secondary or higher thiol compound is not particularly limited, and can be, for example, 5% by weight or more, preferably 15% by weight or more, more preferably 25% by weight or more, or even 35% by weight or more, and can be, for example, 95% by weight or less, preferably 75% by weight or less, or even 60% by weight or less, or even 45% by weight or less.

[0068] Considering the balance between the shelf life of the sealant sheet before use and its curing properties during use, the thiol compound (B) preferably has a thiol equivalent ranging from 45 g / eq to 450 g / eq. The thiol equivalent may be, for example, 60 g / eq or more, 70 g / eq or more, or 80 g / eq or more, or, for example, 350 g / eq or less, 250 g / eq or less, 200 g / eq or less, or 150 g / eq or less. As the thiol equivalent increases, shelf life before use improves, while curing properties during use tend to decrease. When two or more thiol compounds (B) are used, it is preferable that the sum of the products of the thiol equivalents and the weight fractions of the thiol compounds (B) be within the above range. The thiol equivalent refers to the number of grams of a compound containing one equivalent of a thiol group and can be measured by iodometric titration. Alternatively, nominal values ​​listed in catalogs or literature may be used.

[0069] <Allyl Compound (C)> The allyl compound (C) contained in the sealant sheet disclosed herein can be any compound having two or more allyl groups per molecule, without any particular limitation. Although not particularly limited, allyl ethers, allyl esters, and the like can be preferably used as the allyl compound (C) disclosed herein. Examples of the allyl compound (C) disclosed herein include, but are not limited to, bifunctional allyl compounds such as diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl fumarate, diallyl adipate, diallyl hexahydrophthalate, and 1,3-diallyloxy-2-propanol; trifunctional allyl compounds such as triallyl isocyanurate, triallyl cyanurate, triallyl citrate, and triallyl trimellitate; and tetrafunctional allyl compounds such as pentaerythritol tetraallyl ether.

[0070] In the sealant sheet disclosed herein, the ratio of the equivalent weight of allyl groups to the equivalent weight of thiol groups contained in the sealant sheet, i.e., the allyl / thiol ratio of the sealant sheet, is not particularly limited. The allyl / thiol ratio of the sealant sheet may be, for example, approximately 0.1 to 10, 0.2 to 5, 0.3 to 3, or 0.5 to 2. When the allyl / thiol ratio is equal to or greater than any of the lower and upper limits described above, a cured product tends to be formed that exhibits a good balance between strength and elongation. In some embodiments, the allyl / thiol ratio may be, for example, 0.6 or greater, 0.7 or greater, or 0.8 or greater, and may be 1.7 or less, 1.5 or less, or 1.2 or less.

[0071] In the sealant sheet disclosed herein, the amount of thiol compound (B) contained in the sealant sheet is not particularly limited. The amount of thiol compound (B) contained in the sealant sheet can be set, for example, so as to achieve any of the allyl / thiol ratios described above. In some embodiments, the amount of thiol compound (B) that does not correspond to the thiol group-containing polysulfide polymer (AB) relative to 100 parts by weight of polysulfide polymer (A) can be, for example, 0.05 parts by weight or more, or 0.1 parts by weight or more, or 0.3 parts by weight or more, or 0.5 parts by weight or more, or, for example, 10 parts by weight or less, or 5 parts by weight or less, or 3 parts by weight or less, or 2 parts by weight or less.

[0072] In the sealant sheet disclosed herein, the amount of the allyl compound (C) contained in the sealant sheet is not particularly limited. The amount of the allyl compound (C) contained in the sealant sheet can be set, for example, so as to achieve any of the allyl / thiol ratios described above. In some embodiments, the amount of the allyl compound (C) relative to 100 parts by weight of the polysulfide polymer (A) can be, for example, 0.05 parts by weight or more, 0.1 parts by weight or more, 0.3 parts by weight or more, or 0.5 parts by weight or more, or, for example, 10 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, or 2 parts by weight or less.

[0073] <Photoradical generator (D)> The photoradical generator (D) used is one that generates radicals upon irradiation with light. In some preferred embodiments, the photoradical generator (D) is an intramolecular cleavage-type photoinitiator. Examples of the photoradical generator (D) include alkylphenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, titanocene compound-based photopolymerization initiators, acetophenone-based photopolymerization initiators, and benzoin ether-based photopolymerization initiators. The photoradical generators can be used alone or in combination of two or more.

[0074] Specific examples of alkylphenone-based photopolymerization initiators include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (e.g., trade name "Omnirad 907" manufactured by IGM Resins), 2,2-dimethoxy-2-phenylacetophenone (e.g., trade name "Omnirad 651" manufactured by IGM Resins), and the like. Specific examples of the acylphosphine oxide photopolymerization initiator include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (for example, trade name "Irgacure 819" manufactured by BASF), bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (for example, trade name "Lucirin TPO" manufactured by BASF), bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and the like. Specific examples of titanocene compound-based photopolymerization initiators include bis(2,4-cyclopentadienyl)bis[2,6-difluoro-3-(1-pyrryl)phenyl]titanium(IV) (for example, trade name "Irgacure 784" manufactured by BASF). Specific examples of acetophenone-based photopolymerization initiators include 1-hydroxycyclohexyl-phenyl-ketone (e.g., BASF's trade name "Irgacure 184"), 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (e.g., BASF's trade name "Irgacure 2959"), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (e.g., BASF's trade name "Darocur 1173"), methoxyacetophenone, and the like. Specific examples of the benzoin ether-based photopolymerization initiator include benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether, and substituted benzoin ethers such as anisole methyl ether.

[0075] Among these, alkylphenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, and titanocene compound-based photopolymerization initiators are preferred because they can effectively promote the radical addition reaction between a thiol group and an allyl group by radicals generated by light irradiation.

[0076] The amount of the photoradical generator (D) used can be set so as to obtain the desired effect. In some embodiments, the amount of the photoradical generator (D) used can be, for example, 0.01 parts by weight or more relative to 100 parts by weight of the total amount of the polysulfide polymer (A), the thiol compound (B), and the allyl compound (C). From the viewpoint of improving the curing property of the sealant sheet, it is preferably 0.1 parts by weight or more, and may be 0.5 parts by weight or more, 1 part by weight or more, or 1.5 parts by weight or more. Furthermore, from the viewpoint of raw material costs, etc., the amount of the photoradical generator (D) used is usually preferably 10 parts by weight or less relative to 100 parts by weight of the total amount, more preferably 7 parts by weight or less, and may be 5 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, or 2.5 parts by weight or less.

[0077] <Photosensitizer> The sealant sheet disclosed herein may contain a sensitizer. The use of a sensitizer can increase the utilization efficiency of irradiated light and improve the sensitivity of the photoradical generator (D). The photosensitizer can be appropriately selected from known materials.Non-limiting examples of photosensitizers include benzophenone, 4-methylbenzophenone, 3-benzoylbiphenyl, 4-(4-methylphenylthio)benzophenone, methyl 2-benzoylbenzoate, 4-phenylbenzophenone, 4,4'-bis(dimethoxy)benzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 2-benzoylbenzoic acid methyl ester, 2-methylbenzophenone, 3-methylbenzophenone, 3,3'-dimethyl-4-methyl ... benzophenone derivatives such as thoxybenzophenone and 2,4,6-trimethylbenzophenone; thioxanthone derivatives such as thioxanthone, xanthone, 2-chlorothioxanthone, 4-chlorothioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 1-chloro-4-propoxythioxanthone, and 2,4-diethylthioxanthen-9-one; fluorene compounds such as 2-hydroxy-9-fluorenone; anthraquinone anthrone derivatives such as anthraquinone, 2-ethylanthraquinone, 2-hydroxyanthraquinone, and 2-aminoanthraquinone; anthraquinone derivatives such as anthraquinone, 2-ethylanthraquinone, 2-hydroxyanthraquinone, and 2-aminoanthraquinone; 1-methylnaphthalene, 2-methylnaphthalene, 1-fluoronaphthalene, 1-chloronaphthalene, 2-chloronaphthalene, 1-bromonaphthalene, 2-bromonaphthalene, 1-iodonaphthalene, 2-iodonaphthalene, 1-naphthol, 2-naphthol, 1-methoxynaphthalene, and 2-methoxynaphthalene; Examples of suitable compounds include, but are not limited to, naphthalene derivatives such as sinaphthalene, 1,4-dicyanonaphthalene, and methyl 3-hydroxy-2-naphthoate; anthracene derivatives such as anthracene, 1,2-benzanthracene, 9,10-dichloroanthracene, 9,10-dibromoanthracene, 9,10-diphenylanthracene, 9-cyanoanthracene, 9,10-dicyanoanthracene, and 2,6,9,10-tetracyanoanthracene; nitro compounds such as nitrobenzoic acid and nitroaniline; and various dyes.

[0078] When a photosensitizer is used, its amount can be set so as to obtain the desired sensitizing effect. When the sealant sheet contains a thiol compound (B) and an allyl compound (C), the amount of the photosensitizer may be, for example, 0.001 parts by weight or more, 0.005 parts by weight or more, 0.01 parts by weight or more, or 0.05 parts by weight or more, relative to 100 parts by weight of the total amount of the thiol compound (B) and the allyl compound (C). When the sealant sheet does not contain a thiol compound that does not fall under the thiol group-containing polysulfide polymer (AB), the amount of the photosensitizer may be, for example, 0.002 parts by weight or more, 0.01 parts by weight or more, 0.02 parts by weight or more, or 0.1 parts by weight or more, relative to 100 parts by weight of the allyl compound (C). The upper limit of the amount of photosensitizer used is not particularly limited, but from the viewpoint of shelf life of the sealant sheet, when the sealant sheet contains a thiol compound (B) and an allyl compound (C), the amount is typically 10 parts by weight or less, or may be 5 parts by weight or less, 1 part by weight or less, 0.5 parts by weight or less, or 0.3 parts by weight or less, per 100 parts by weight of the total amount of the thiol compound (B) and the allyl compound (C). When the sealant sheet does not contain a thiol compound that does not fall under the thiol group-containing polysulfide polymer (AB), the amount of photosensitizer used is typically 20 parts by weight or less, or may be 10 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or 0.6 parts by weight or less, per 100 parts by weight of the allyl compound (C). In a preferred embodiment, the sealant sheet disclosed herein does not contain a photosensitizer.

[0079] <Storage stabilizer> The sealant sheet disclosed herein may further contain any compound that can help inhibit the radical addition reaction between thiol groups and allyl groups, provided that other properties are not significantly impaired. The use of such a compound can improve the shelf life of the sealant sheet before use. The storage stabilizer may be, for example, an organic acid or inorganic acid that is liquid or solid at room temperature, or an oligomer, polymer, borate ester, or phosphate ester containing an acidic group in its molecule, and may also have a functional group other than the acidic group. Examples of storage stabilizers include, but are not limited to, sulfuric acid, acetic acid, adipic acid, tartaric acid, fumaric acid, barbituric acid, boric acid, pyrogallol, phenolic resin, and carboxylic acid anhydride. The storage stabilizer may be used alone or in combination with two or more suitable compounds. The amount of storage stabilizer used is not particularly limited and can be determined to achieve the desired effect.

[0080] Suitable examples of the storage stabilizer include boric acid esters and phosphoric acid esters. The borate esters are liquid or solid at room temperature, and examples thereof include, but are not limited to, trimethyl borate, triethyl borate, tri-n-propyl borate, triisopropyl borate, tri-n-butyl borate, tripentyl borate, triallyl borate, trihexyl borate, tricyclohexyl borate, trioctyl borate, trinonyl borate, tridecyl borate, tridodecyl borate, trihexadecyl borate, trioctadecyl borate, tris(2-ethylhexyloxy)borane, bis(1,4,7,10-tetraoxaundecyl)(1,4,7,10,13-pentaoxatetradecyl)(1,4,7-trioxaundecyl)borane, tribenzyl borate, triphenyl borate, tri-o-tolyl borate, tri-m-tolyl borate, and triethanolamine borate. Examples of phosphate esters include, but are not limited to, ethyl phosphate, butyl phosphate, propyl phosphate, 2-ethylhexyl phosphate, dibutyl phosphate, di(2-ethylhexyl) phosphate, oleyl phosphate, ethyl diethyl phosphate, etc. In one preferred embodiment, the sealant sheet disclosed herein does not contain a storage stabilizer.

[0081] <Filler> The sealant sheet disclosed herein can be blended with a filler as needed. This can improve one or both of the breaking strength and elongation at break of the cured product. The filler can also be useful for adjusting the storage modulus of the sealant sheet. Furthermore, appropriate use of a filler can improve the shape retention and processability of the sealant sheet. There are no particular restrictions on the filler used, and any appropriate filler can be used as long as it does not significantly impair the effects obtained by the technology disclosed herein. The fillers can be used alone or in combination of two or more.

[0082] Examples of materials constituting the filler include, but are not limited to, talc, silica, glass, carbon black, alumina, clay, mica, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, barium sulfate, titanium dioxide, barium titanate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, boron nitride, aluminum borate, barium zirconate, calcium zirconate, etc. Among these, preferred examples include talc, silica, glass, and calcium carbonate.

[0083] The filler content is not particularly limited and can be selected to obtain suitable properties. The filler content may be, for example, 1% by weight or more, or 5% by weight or more, based on the total sealant sheet. From the viewpoint of obtaining a higher usage effect, it may be 10% by weight or more, 15% by weight or more, 20% by weight or more, or 25% by weight or more. The filler content may be, for example, less than 50% by weight based on the total sealant sheet. From the viewpoint of improving formability into a sheet shape and elongation of the cured product, it is usually appropriate to set it to less than 40% by weight, and it may even be less than 35% by weight. In some embodiments, the filler content may be less than 30% by weight or less than 25% by weight.

[0084] The average particle size of the filler is not particularly limited. The average particle size is usually suitably 100 μm or less, preferably 50 μm or less. A smaller average particle size tends to improve the effect of improving one or both of the breaking strength and elongation at break of the cured product. In some embodiments, the average particle size of the filler may be, for example, 30 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, or 5 μm or less. Furthermore, the average particle size of the filler may be, for example, 0.1 μm or more, 0.2 μm or more, 0.5 μm or more, or 1 μm or more. A not-too-small average particle size can be advantageous in terms of the handleability and dispersibility of the filler.

[0085] In this specification, the average particle size of the filler refers to the particle size at which the cumulative particle size on a volume basis is 50% in the particle size distribution obtained by measurement based on the laser diffraction / scattering method, i.e., the 50% volume average particle size (50% median diameter).

[0086] In some embodiments, a filler made of a material having a refractive index in the range of 1.56 or more to less than 1.62 can be preferably used. For example, a glass filler having a refractive index in the above range can be used. The above refractive index range is equal to or close to the refractive index of the polysulfide polymer (A) (typically about 1.60). Therefore, fillers having a refractive index in the above range tend to suppress the decrease in the transmittance of the sealant sheet caused by the incorporation of the filler compared to fillers having a refractive index outside the above range. When a sealant sheet has a certain degree of transmittance, it becomes easier to observe the area to be sealed through the sealant sheet. This can be advantageous from the viewpoint of, for example, the positioning ease when placing the sealant sheet in a predetermined location. The transmittance of the sealant sheet disclosed herein may be, for example, greater than 5%, greater than 10%, greater than 15%, or greater than 20%. The upper limit of the transmittance is not particularly limited. The transmittance of the sealant sheet disclosed herein may be 100%, or from a practical viewpoint, may be 80% or less, 60% or less, or 40% or less. The sealant sheet disclosed herein can also be preferably implemented in an embodiment in which the transmittance is 30% or less, 20% or less, or 15% or less. The transmittance of the sealant sheet can be determined by measuring the spectrum of a 0.2 mm thick sealant sheet using a UV-vis spectrum measuring device (Shimadzu Corporation, UV-2550) or its equivalent. The transmittance can be, for example, the transmittance at a wavelength of 365 nm.

[0087] The sealant sheet disclosed herein may use a combination of a filler (e.g., glass filler) having a refractive index in the range of 1.56 to less than 1.62 and a filler (e.g., talc) having a refractive index outside this range. In this case, the proportion of fillers having a refractive index in the above range relative to the total amount of fillers contained in the sealant sheet may be, for example, 10% by weight or more, 25% by weight or more, preferably 45% by weight or more, 60% by weight or more, 85% by weight or more, or even 100%. In some embodiments, fillers made of materials having a refractive index in the range of 1.56 to 1.61 or 1.57 to 1.60 may be more preferably used. The refractive index can be measured using commonly known techniques such as the minimum deviation method, critical angle method, and V-block method. Measurement can be performed using, for example, a multi-wavelength Abbe refractometer DR-M4 (manufactured by ATAGO). Alternatively, nominal values ​​listed in catalogs or literature may be used.

[0088] The sealant sheet disclosed herein may contain other optional components to the extent that the effects obtained by the technology disclosed herein are not significantly impaired. Examples of such optional components include, but are not limited to, colorants such as dyes and pigments, dispersants, plasticizers, softeners, flame retardants, antioxidants, UV absorbers, antioxidants, light stabilizers, etc.

[0089] The sealant sheet disclosed herein may further contain a polymer or oligomer (hereinafter also referred to as an optional polymer) other than those described above, for example, to improve adhesion to the area to be sealed. From the viewpoint of the oil resistance of the cured product, the content of the optional polymer is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and even more preferably 1 part by weight or less, per 100 parts by weight of the polysulfide polymer (A). The sealant sheet may be substantially free of such optional polymer. In this specification, "substantially free of a certain component" means that, unless otherwise specified, the component is not, at least intentionally, included.

[0090] The sealant sheet disclosed herein may contain, for example, 5% or less, 2% or less, 1% or less, or 0.5% or less of an organic solvent by weight of the sealant sheet, or may be substantially free of an organic solvent. The organic solvent content may be 0%. Here, organic solvent refers to a component such as toluene, cyclohexanone, or trichloroethane that is not intended to react with other components in the sealant sheet (particularly the epoxy group-containing polysulfide and the curing agent that may be used as needed).

[0091] The sealant sheet disclosed herein may contain a thiol compound (B) (hereinafter also referred to as a low-molecular-weight thiol compound) having an Mw of 1000 or less, preferably 600 or less, and more preferably 400 or less. The content of the low-molecular-weight thiol compound may be, for example, 0.1 wt % or more, 0.3 wt % or more, or 0.5 wt % or more of the total amount of the thiol compound (B) and the polysulfide polymer (A) by weight. The low-molecular-weight thiol compound may enhance the tackiness of the sealant sheet disclosed herein. Increasing the tackiness of the sealant sheet may improve the temporary fixation of the sealant sheet placed at the target sealing location to the target sealing location. The temporary fixation refers to the property of preventing the sealant sheet from lifting or shifting from the target sealing location until the sealant sheet placed at the target sealing location cures. The low-molecular-weight thiol compound reacts with light irradiation and is incorporated into the cured product. In some embodiments, the content of the low-molecular-weight thiol compound may be less than 0.1 wt % or less than 0.05 wt % of the total amount of the thiol compound (B) and the polysulfide polymer (A), or may be substantially absent. Even in such an embodiment, the sealant sheet disclosed herein may have tack on its surface and be capable of being temporarily fixed to the area to be sealed.

[0092] <Release liner> A release liner can be used during the preparation of the sealant sheet disclosed herein (e.g., forming into a sheet), storage of the sealant sheet before use, distribution, shaping, and placement at the sealing target location. The release liner is not particularly limited, and examples include release liners having a release treatment layer on the surface of a liner substrate such as a resin film or paper, and release liners made of low-adhesion materials such as fluorine-based polymers (e.g., polytetrafluoroethylene) and polyolefin-based resins (e.g., polyethylene and polypropylene). The release treatment layer can be formed by surface-treating the liner substrate with a release treatment agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide.

[0093] <Method of manufacturing sealant sheet> Below, several embodiments of the method for producing a sealant sheet disclosed herein are described. However, the following description is for illustrative purposes only and does not limit the method for producing a sealant sheet disclosed herein. For example, for the sake of convenience, the following description mainly focuses on embodiments that use a filler, but this does not mean that the sealant sheet disclosed herein is limited to embodiments that include a filler.

[0094] In a preferred embodiment, the sealant sheet disclosed herein comprises a combination of a polysulfide polymer (A), a thiol compound (B) (e.g., the low-molecular-weight thiol compound described above), and an allyl compound (C). A sealant sheet having such a composition can be produced, for example, by a method comprising: preparing a polysulfide polymer (A); adding and mixing the thiol compound (B), the allyl compound (C), the photoradical generator (D), and a filler to the polysulfide polymer (A); and molding the resulting mixture into a sheet. When the polysulfide polymer (A) is a reaction product of a thiol-containing polysulfide, a bifunctional epoxy compound, and a multifunctional epoxy compound, preparing the mixture may comprise, in this order, preparing a reaction product of the thiol-containing polysulfide, the bifunctional epoxy compound, and the multifunctional epoxy compound; and adding and mixing the thiol compound (B), the allyl compound (C), the photoradical generator (D), and a filler to the reaction product. Alternatively, the filler may be mixed together when preparing the reaction product.

[0095] The above-mentioned explanation regarding the reaction between the thiol group-containing polysulfide and the epoxy compound having two or more epoxy groups per molecule can be applied to the preparation of the reaction product, so a redundant explanation will be omitted. Examples of devices that can be used to mix the reaction product with the additive components (in the above example, the thiol compound (B), the allyl compound (C), the photoradical generator (D), and the filler) include, but are not limited to, internal mixers or batch mixers such as a Banbury mixer, a kneader, a two-roll mill, or a three-roll mill; and continuous mixers such as a single-screw extruder or a twin-screw extruder.

[0096] The mixture can be formed into a sheet by known sheet forming methods such as press molding, calendar molding, and melt extrusion molding, either alone or in appropriate combination. The press molding may be atmospheric press or vacuum press. From the viewpoint of preventing air bubbles from being trapped in the sheet and suppressing thermal denaturation of the mixture, vacuum press molding or calendar molding may be preferably used in some embodiments. The obtained sealant sheet can be stored, processed (for example, slit to a predetermined width, processed from a roll into sheets, punched into a predetermined shape, etc.), transported, etc., in the form of a sealant sheet with a release liner, for example, as shown in FIG. 1 or FIG. 2.

[0097] In a preferred embodiment, the sealant sheet disclosed herein comprises a combination of a thiol group-containing polysulfide polymer (AB) and an allyl compound (C). A sealant sheet having such a composition can be produced, for example, by a method comprising: preparing a thiol group-containing polysulfide polymer (AB); adding and mixing the allyl compound (C), a photoradical generator (D), and a filler to the thiol group-containing polysulfide polymer (AB); and molding the resulting mixture into a sheet. When the thiol group-containing polysulfide polymer (AB) is a thiol-modified epoxy group-containing polysulfide polymer, preparing the mixture may comprise, in this order, preparing the thiol group-containing polysulfide polymer (AB) by reacting the thiol groups of a compound having two or more thiol groups per molecule with the epoxy groups of the epoxy group-containing polysulfide polymer; and adding and mixing the allyl compound (C), the photoradical generator (D), and a filler to the thiol group-containing polysulfide polymer (AB). Alternatively, the filler may be mixed together when preparing the reaction product.

[0098] <Application (How to use)> The material of the portion to be sealed using the sealant sheet disclosed herein is not particularly limited. The material may be, for example, a metal, a resin, a composite material thereof, or the like. More specifically, the material may be a metal or semi-metallic material such as iron, iron alloys (carbon steel, stainless steel, chromium steel, nickel steel, etc.), aluminum, aluminum alloys, nickel, tungsten, copper, copper alloys, titanium, titanium alloys, or silicon; a resin material such as polyolefin resin, polycarbonate resin, acrylic resin, or acrylonitrile resin (PAN); a ceramic material such as alumina, silica, sapphire, silicon nitride, tantalum nitride, titanium carbide, silicon carbide, gallium nitride, or gypsum; a glass material such as aluminosilicate glass, soda-lime glass, soda-aluminosilicate glass, or quartz glass; or a laminate or composite thereof. Suitable examples of the metal or semi-metallic material include light metals such as aluminum and titanium, or alloys primarily composed of such light metals. An example of an aluminum alloy is duralumin (e.g., duralumin A2024, duralumin A2017, etc.). Examples of the composite material include carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (FRP).

[0099] The sealant sheet disclosed herein is in the form of a non-liquid (i.e., solid) sheet at temperatures around 25°C. Therefore, unlike liquid sealants, there is no need for the operator to control the thickness when placing it on the sealing target area. Furthermore, unlike liquid sealants, the sealant sheet can be pre-cut to the desired shape and then placed on the sealing target area (typically, by utilizing the tack of the sealant sheet). Alternatively, a roll-shaped sealing sheet can be unwound and applied to the target area, with the excess sealing sheet then cut off. Use of the sealant sheet disclosed herein can fundamentally solve problems such as dripping, uneven application, and spillage that occur when applying liquid sealants, thereby significantly reducing work time.

[0100] In the sealant sheet disclosed herein, light irradiation is performed to generate radicals from the photoradical generator (D), which promotes a radical addition reaction between the thiol and allyl groups contained in the sealant sheet, thereby promoting the curing of the sheet. Light irradiation can be performed using a known appropriate light source, such as a chemical lamp, a black light (e.g., a black light manufactured by Toshiba Lighting & Technology Corporation), or a metal halide lamp. In some embodiments, a light source having a spectral distribution in the wavelength range of 250 nm to 450 nm can be preferably used. The use of a sensitizer in the sealant sheet can improve the utilization efficiency of light emitted from the light source. For example, when using a light source having a spectral distribution in the wavelength range of 350 nm to 450 nm, the use of a sensitizer is particularly effective.

[0101] The sealant sheet disclosed herein can be used in a form in which it is irradiated with light while placed at the location to be sealed. Because the radical addition reaction (thiol-ene addition reaction) between thiol groups and allyl groups proceeds more quickly than anionic polymerization, etc., the sealant sheet disclosed herein tends to cure quickly after light irradiation. According to the technology disclosed herein, even in a sealant sheet that cures in a time shorter than the time it takes for air bubbles to fully escape to the outside of the sealant after light irradiation, the generation and growth of air bubbles is suppressed, making it suitable for use in applications requiring a shorter sealing time and high sealing quality.

[0102] The cured product formed from the sealant sheet disclosed herein or the cured sealant product suitably has a tensile break strength of 0.7 MPa or more, preferably 0.9 MPa or more, more preferably greater than 1.0 MPa, and may be 1.1 MPa or more or 1.15 MPa or more. In some embodiments, the tensile break strength may be 1.2 MPa or more, or may be 1.3 MPa or more. There is no particular upper limit to the tensile break strength, but from the viewpoint of easily achieving compatibility with other physical properties, it may be, for example, 3 MPa or less. Furthermore, the cured product formed from the sealant sheet disclosed herein or the cured sealant product suitably has an elongation at break of 100% or more, preferably 120% or more, or may be 150% or more, 200% or more, or 250% or more. There is no particular upper limit to the elongation at break, but from the viewpoint of easily achieving compatibility with other physical properties, it may be, for example, 600% or less, or even 400% or less.

[0103] The tensile strength at break and elongation at break are measured by the following methods. (Measurement of tensile strength and elongation at break) One side of a 0.2 mm thick sealant sheet was exposed to 2000 mJ / cm using a black light manufactured by Toshiba Lighting & Technology Corporation. 2 The irradiated sealant sheet is then kept in a 25°C environment for 14 days, and the resulting cured product (sealant cured product) is then cut into a rectangular shape 10 mm wide and 50 mm long to prepare a sample piece. This sample piece is clamped between the chucks of a tensile tester with a 20 mm gap between the chucks and pulled at a rate of 50 mm / min in accordance with JIS K6767. The maximum strength observed before the sample breaks is taken as the tensile breaking strength. Furthermore, the chuck distance L1 when the sample breaks and the chuck distance L0 when pulling begins are used to calculate the tensile breaking strength using the following formula: Elongation at break (%) = ((L1-L0) / L0) × 100; The elongation at break is calculated by the following.

[0104] The matters disclosed by this specification include the following: (1) A sealant sheet formed into a sheet shape, Ingredients: Polysulfide polymer (A); a thiol compound (B) having two or more thiol groups in one molecule; An allyl compound (C) having two or more allyl groups in one molecule; and Photoradical generator (D); Includes sealant sheets. (2) The sealant sheet according to (1) above, wherein the polysulfide polymer (A) is an epoxy group-containing polysulfide polymer (AA) having two or more epoxy groups. (3) The sealant sheet according to (2) above, wherein the epoxy group-containing polysulfide polymer (AA) is a polysulfide polymer having epoxy groups at both ends. (4) The sealant sheet according to (2) or (3) above, wherein the epoxy group-containing polysulfide polymer (AA) is a reaction product of a thiol polysulfide having a Mw of 500 to 10,000 and a disulfide structure in the main chain, and an epoxy compound having two or more epoxy groups in one molecule. (5) The sealant sheet according to (4) above, wherein the epoxy compound includes a difunctional epoxy compound. (6) The sealant sheet according to (5) above, wherein the bifunctional epoxy compound contains an epoxy compound containing a five- or more-membered carbon ring structure in the molecule. (7) The sealant sheet according to any one of (4) to (6) above, wherein the epoxy compound contains a polyfunctional epoxy compound having three or more functionalities. (8) The sealant sheet according to (7) above, wherein the polyfunctional epoxy compound contains a novolac epoxy resin. (9) The sealant sheet according to any one of (1) to (8) above, wherein the polysulfide polymer (A) is a thiol group-containing polysulfide polymer (AB) having two or more thiol groups. (10) The sealant sheet according to (9) above, wherein the thiol group-containing polysulfide polymer (AB) is a polysulfide polymer having thiols at both ends. (11) The sealant sheet according to (9) or (10) above, wherein the thiol group-containing polysulfide polymer (AB) is a reaction product between a both-terminal epoxy polysulfide having a Mw of 500 to 10,000 and a disulfide structure in the main chain, and a thiol compound having two or more thiol groups in one molecule. (12) The sealant sheet according to any one of (1) to (11) above, wherein the thiol compound (B) has a thiol equivalent of 45 g / eq or more and 450 g / eq or less. (13) The sealant sheet according to any one of (1) to (12) above, wherein the allyl compound (C) is at least one selected from the group consisting of bifunctional allyl compounds and trifunctional allyl compounds.

[0105] (14) The sealant sheet according to any one of (1) to (13), wherein the photoradical generator (D) is at least one selected from the group consisting of alkylphenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, and titanocene compound-based photopolymerization initiators. (15) The sealant sheet according to any one of (1) to (14) above, further comprising a filler. (16) The sealant sheet according to (15) above, wherein the content of the filler is 1% by weight or more and less than 40% by weight of the entire sealant sheet. (17) The sealant sheet according to (15) or (16) above, wherein the filler has an average particle size of 0.1 μm or more and 30 μm or less. (18) The sealant sheet according to any one of (1) to (17) above, having a storage modulus at 25°C of 0.005 MPa or more and 0.8 MPa or less. (19) The sealant sheet according to any one of (1) to (18) above, having a thickness of 0.01 mm or more and 10 mm or less. (20) A sealant sheet formed into a sheet shape, Ingredients: a thiol group-containing polysulfide polymer (AB) having two or more thiol groups; An allyl compound (C) having two or more allyl groups in one molecule; and Photoradical generator (D); Includes sealant sheets.

[0106] (21) A sealant sheet according to any one of (1) to (20) above, a release liner having a release surface that contacts at least one surface of the sealant sheet; A sealant sheet with a release liner, comprising: (22) Providing a polysulfide polymer (A); adding and mixing a thiol compound (B) having two or more thiol groups in one molecule, an allyl compound (C) having two or more allyl groups in one molecule, a photoradical generator (D), and a filler to the polysulfide polymer (A); and forming the resulting mixture into a sheet shape; A method for manufacturing a sealant sheet, comprising: (23) preparing a thiol group-containing polysulfide polymer (AB) having two or more thiol groups in one molecule; adding and mixing an allyl compound (C) having two or more allyl groups in one molecule, a photoradical generator (D), and a filler to the thiol group-containing polysulfide polymer (AB); and forming the resulting mixture into a sheet shape; A method for manufacturing a sealant sheet, comprising: (24) Preparing the sealant sheet according to any one of (1) to (20) above, Affixing the sealant sheet to an object to be sealed; curing the sealant sheet on the object to be sealed to form a cured sealant; Including, Here, the sealing method comprises irradiating the sealant sheet with light immediately before and / or after the sealant sheet is attached to the object to be sealed. [Example]

[0107] Hereinafter, several examples of the present invention will be described, but it is not intended that the present invention be limited to those shown in these examples. In the following description, "parts" are by weight unless otherwise specified.

[0108] Example 1 <Preparation of Dual-Terminated Epoxy Polysulfide Polymer> In a reaction vessel equipped with a stirrer, 90 parts of a liquid polysulfide polymer (double-ended thiol polysulfide polymer), 7.5 parts of a bifunctional epoxy compound, 2 parts of a multifunctional epoxy compound, and 0.08 parts of a basic catalyst were heated at 90°C for 3 hours with stirring, thereby synthesizing a double-ended epoxy polysulfide polymer. Here, the liquid polysulfide polymer (double-ended thiol polysulfide polymer) used was Thiokol LP-55 (product name: MW 4000, thiol equivalent: 2000 g / eq) manufactured by Toray Fine Chemical Co., Ltd., the bifunctional epoxy compound used was bisphenol F type epoxy resin (product name: jER806, epoxy equivalent: 169 g / eq) manufactured by Mitsubishi Chemical Corporation, the multifunctional epoxy compound used was phenol volac type epoxy resin (product name: jER152, epoxy equivalent: 177 g / eq) manufactured by Mitsubishi Chemical Corporation, and the basic catalyst used was 2,4,6-triaminomethylphenol manufactured by Tokyo Chemical Industry Co., Ltd.

[0109] <Preparation of sealant sheet> The contents of the reaction vessel were removed and allowed to cool to room temperature. Then, 50 parts of the epoxy-terminated polysulfide polymer were mixed with 0.5 parts of a secondary difunctional thiol compound (see Table 1), 0.6 parts of a trifunctional allyl compound, 1.0 parts of photoradical generator A, and 20 parts of talc filler, and the mixture was kneaded uniformly using a two-roll mill. The resulting mixture was formed into a sheet using a vacuum press to obtain the sealant sheet of this example. Two types of sheets, 0.2 mm thick and 1 mm thick, were produced.

[0110] The allyl / thiol ratio of the sealant sheet according to this example is 1.0. That is, the total number of thiol groups (unreacted) contained in the double-terminated epoxy polysulfide polymer used to prepare the sealant sheet according to this example and the thiol groups (unreacted) contained in the secondary difunctional thiol compound added to this polymer is almost equal to the number of allyl groups (unreacted) contained in the trifunctional allyl compound added to the polymer. The number of thiol groups contained in the double-terminated epoxy polysulfide polymer is calculated from the thiol equivalent and the amount used of the liquid polysulfide polymer used to synthesize the polymer, N T The number of epoxy groups N calculated from the epoxy equivalent and the amount of each of the bifunctional epoxy compound and polyfunctional epoxy compound used E It can be found by subtracting

[0111] Example 2 <Preparation of Polysulfide Polymer with Thiol Ends> Using a reaction vessel equipped with a stirrer, 90 parts of a liquid polysulfide polymer (a dual-terminated thiol polysulfide polymer), 10 parts of a bifunctional epoxy compound, 2 parts of a multifunctional epoxy compound, and 0.08 parts of a basic catalyst were heated at 90°C for 3 hours with stirring. Next, 4 parts of a bifunctional thiol compound were added, and the mixture was heated at 90°C for 1.5 hours with stirring. This synthesized a dual-terminated thiol polysulfide polymer. The liquid polysulfide polymer (double-ended thiol polysulfide polymer) used was Toray Fine Chemical Co., Ltd.'s Thiokol LP-55 (Mw 4000, thiol equivalent 2000 g / eq), the bifunctional epoxy compound was Mitsubishi Chemical Corporation's bisphenol F epoxy resin (product name jER806, epoxy equivalent 169 g / eq), the multifunctional epoxy compound was Mitsubishi Chemical Corporation's phenol borac epoxy resin (product name jER152, epoxy equivalent 177 g / eq), the basic catalyst was Tokyo Chemical Industry Co., Ltd.'s 2,4,6-triaminomethylphenol, and the bifunctional thiol compound was Tokyo Chemical Industry Co., Ltd.'s 3,6-dioxa-1,8-octanedithiol (thiol equivalent 91 g / eq).

[0112] <Preparation of sealant sheet> The contents of the reaction vessel were removed and allowed to cool to room temperature. Then, 50 parts of the epoxy-terminated polysulfide polymer were mixed with 0.5 parts of a secondary difunctional thiol (see Table 1), 0.6 parts of a trifunctional allyl compound, 1.0 parts of photoradical generator A, and 20 parts of talc filler, and the resulting mixture was kneaded uniformly using a two-roll mill. The resulting mixture was formed into a sheet using a vacuum press to obtain the sealant sheet of this example. Two types of sheets, 0.2 mm thick and 1 mm thick, were produced.

[0113] (Comparative Example 1) Using a reaction vessel equipped with a stirrer, 46 parts of a liquid polysulfide polymer (a polysulfide polymer having thiol groups at both ends) shown in Table 1, 8.82 parts of a secondary difunctional thiol, 5.46 parts of a primary difunctional thiol, 9.96 parts of a trifunctional allyl compound, 0.4 parts of a photoradical generator A, and 20 parts of talc as a filler were added and mixed. The resulting mixture was in a liquid state at room temperature. The above mixture was used as the sealant of this example.

[0114] (Comparative Examples 2 to 4) The sealants of each example were prepared in the same manner as in Comparative Example 1, except that the type of photoradical generator used was as shown in Table 1. All of the sealants of Comparative Examples 2 to 4 were in a liquid state at room temperature.

[0115] The sealant sheets of Examples 1 and 2 were subjected to the following measurements and evaluations. (Measurement of storage modulus) A 1 mm thick sealant sheet was punched out into an 8 mm diameter disk, sandwiched between parallel plates, and the storage modulus G' was measured using a viscoelasticity tester (TA Instruments Japan, model name "ARES G2") at a measurement temperature of 25°C, a frequency of 1 Hz, and a strain of 0.5%. As a result, the storage modulus G' of the sealant sheets of Examples 1 and 2 was in the range of 0.005 MPa to 0.8 MPa.

[0116] (Appearance and curing evaluation) A 38 μm thick transparent PET film (Mitsubishi Polyester, Diafoil MRF38) was attached to both sides of a 0.2 mm thick sealant sheet, and then a black light manufactured by Toshiba Lighting & Technology Corporation was used to irradiate the sealant sheet from one side with 2000 mJ / cm. 2 The sealant sheet was then irradiated with light for 10 seconds. The tester then visually inspected the appearance of the sealant sheet through the transparent PET film to determine whether or not any air bubbles were present inside the sealant sheet. If any air bubbles were observed visually, the sealant sheet was rated as "present," and if no air bubbles were observed visually, the sealant sheet was rated as "absent." After the light irradiation, the tester touched the surface of the sealant sheet with his or her hand through the transparent PET film to determine whether or not the sealant sheet had cured. If the sealant sheet had cured, the curing was rated as "good," and if it had not cured, the curing was rated as "poor." The results are shown in the relevant sections of Table 1.

[0117] The sealants of Comparative Examples 1 to 4 were evaluated as follows. Approximately 1 g of sealant was sampled and dropped onto a 38 μm thick transparent PET film (Diafoil MRF38, manufactured by Mitsubishi Polyester), and another 38 μm thick transparent PET film (Diafoil MRF38, manufactured by Mitsubishi Polyester) was placed on top of it to sandwich the sealant. Next, a black light manufactured by Toshiba Lighting & Technology Corporation was used to illuminate the sealant from one side at 2000 mJ / cm. 2 After the light irradiation, the tester visually inspected the appearance of the sealant through the transparent PET film to determine whether or not any air bubbles were present inside the sealant. If air bubbles were observed visually, the sealant was rated as "present," and if no air bubbles were observed visually, the sealant was rated as "absent." After the light irradiation, the tester touched the surface of the sealant through the transparent PET film with his or her hand to determine whether or not the sealant had cured. If the sealant had cured, the sealant was rated as "good" in terms of curability, and if it had not cured, the sealant was rated as "poor." The results are shown in the relevant sections of Table 1.

[0118] [Table 1]

[0119] The sealant sheets of Examples 1 and 2 were both formed into flexible sheets before light irradiation and stably maintained the sheet shape. The sealant sheets of Examples 1 and 2 exhibited good curing properties upon light irradiation, and no air bubbles were observed inside the sheets after curing. When sealant sheets were prepared in the same manner as in Examples 1 and 2, except that photoradical generator A was replaced with photoradical generator B, C, or D, they all exhibited good curing properties equivalent to those of Examples 1 and 2, and it was confirmed that no air bubbles were observed inside the sheets after curing.

[0120] The sealants according to Comparative Examples 1 to 4 exhibited good curing properties when irradiated with light, but air bubbles were observed in all of the sealants after curing.

[0121] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. [Explanation of symbols]

[0122] 21 Sealant Sheet 21A One surface 21B Other surface 31,32 Release liner 100,200 Sealant sheet with release liner

Claims

1. A sealant sheet formed into a sheet shape, Ingredients: Polysulfide polymer (A); a thiol compound (B) having two or more thiol groups in one molecule; An allyl compound (C) having two or more allyl groups in one molecule; and Photoradical generator (D); Includes sealant sheets.

2. The sealant sheet according to claim 1, wherein the thiol compound (B) has a thiol equivalent of 45 g / eq or more and 450 g / eq or less.

3. The sealant sheet according to claim 1 or 2, wherein the allyl compound (C) comprises at least one selected from the group consisting of bifunctional allyl compounds and trifunctional allyl compounds.

4. 4. The sealant sheet according to claim 1, wherein the photoradical generator (D) is at least one selected from the group consisting of alkylphenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, and titanocene compound-based photopolymerization initiators.

5. The sealant sheet according to claim 1 , further comprising a filler.

6. The sealant sheet according to claim 1 , wherein the storage modulus at 25° C. is 0.005 MPa or more and 0.8 MPa or less.

7. A sealant sheet formed into a sheet shape, Ingredients: a thiol group-containing polysulfide polymer (AB) having two or more thiol groups in one molecule; An allyl compound (C) having two or more allyl groups in one molecule; and Photoradical generator (D); Includes sealant sheets.

8. The sealant sheet according to any one of claims 1 to 7, a release liner having a release surface that contacts at least one surface of the sealant sheet; A sealant sheet with a release liner, comprising:

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