Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/30—Low-molecular-weight compounds
  • C08G18/38—Low-molecular-weight compounds having heteroatoms other than oxygen
  • C08G18/3855—Low-molecular-weight compounds having heteroatoms other than oxygen having sulfur
  • C08G18/3876—Low-molecular-weight compounds having heteroatoms other than oxygen having sulfur containing mercapto groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/08—Processes
  • C08G18/16—Catalysts
  • C08G18/22—Catalysts containing metal compounds
  • C08G18/24—Catalysts containing metal compounds of tin
  • C08G18/244—Catalysts containing metal compounds of tin tin salts of carboxylic acids
  • C08G18/246—Catalysts containing metal compounds of tin tin salts of carboxylic acids containing also tin-carbon bonds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
  • C08G18/72—Polyisocyanates or polyisothiocyanates
  • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
  • C08G18/76—Polyisocyanates or polyisothiocyanates cyclic aromatic
  • C08G18/7614—Polyisocyanates or polyisothiocyanates cyclic aromatic containing only one aromatic ring
  • C08G18/7628—Polyisocyanates or polyisothiocyanates cyclic aromatic containing only one aromatic ring containing at least one isocyanate or isothiocyanate group linked to the aromatic ring by means of an aliphatic group
  • C08G18/7642—Polyisocyanates or polyisothiocyanates cyclic aromatic containing only one aromatic ring containing at least one isocyanate or isothiocyanate group linked to the aromatic ring by means of an aliphatic group containing at least two isocyanate or isothiocyanate groups linked to the aromatic ring by means of an aliphatic group having a primary carbon atom next to the isocyanate or isothiocyanate groups, e.g. xylylene diisocyanate or homologues substituted on the aromatic ring
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
  • C09J175/04—Polyurethanes

Definitions

• the present invention relates to a curable composition suitable as an optical adhesive used for producing a composite optical element.
• Photocurable compositions such as acrylate compounds are widely used as adhesives when producing optical elements.
• Adhesives, photocurability, mechanical strength, durability, and optical properties are basic performances for adhesives, but in recent years, the refractive index has become an important performance as optical elements become more sophisticated. . In particular, increasing the refractive index of the adhesive is highly desired because the degree of freedom in optical design is expanded.
• Examples of applications in which an adhesive having a high refractive index is used include an achromatic lens (achromatic lens) composed of two lenses bonded together, a hybrid aspherical lens composed of a composite of glass and resin, and dichroic Examples include prisms having complicated shapes such as prisms.
• Adhesives used for these applications naturally require not only a high refractive index but also performance such as adhesion, photocurability, colorless transparency, and viscosity suitable for work.
• the refractive index of a cured product of bis (2,3-epithiopropyl) sulfide is 1.70. Since the episulfide compound has a low viscosity and can be easily injected into a mold, it is suitable for producing a molded article such as a spectacle lens. However, assuming use as an adhesive, if the viscosity is too low, the adhesive may sag or flow, and the adherend may be displaced during pasting, which causes problems in workability. Moreover, since the episulfide compound generally has a large shrinkage due to curing, when used as an adhesive, it causes a decrease in adhesion.
• Japanese Patent Laid-Open No. 9-71580 Japanese Patent Laid-Open No. 9-110979 Japanese Patent Laid-Open No. 9-255781 JP 2001-163874 A
• an object of the present invention is to provide a curable composition having a high refractive index and also having performances required as an optical adhesive such as photocurability, low shrinkage, colorless transparency, and viscosity suitable for work. Is to provide.
• the present inventors have found that a polythiourethane oligomer (component A), an episulfide compound (component B) and a photobase generator (C) obtained by reacting polythiol and polyisocyanate. It has been found that the curable composition containing the component) is suitable as an optical adhesive because it has a viscosity suitable for workability as an adhesive and has little shrinkage due to curing. Based on the above findings, the present invention has been achieved.
• a curable composition having a high refractive index and also having performance as an optical adhesive such as photocurability, low shrinkage, colorless transparency and viscosity suitable for work. be able to.
• the curable composition of the present invention comprises a polythiourethane oligomer (A component) obtained by reacting polythiol and polyisocyanate, an episulfide compound (B component), and a photobase generator (C component). .
• a component polythiourethane oligomer obtained by reacting polythiol and polyisocyanate, an episulfide compound (B component), and a photobase generator (C component).
• the polythiol used as a raw material for the polythiourethane oligomer is a compound having two or more thiol groups in one molecule, and may be any of linear, branched, and cyclic.
• compounds represented by the following general formulas (1) to (3) are preferable.
• p1 and p2 each independently represents an integer of 0 to 1
• X 1 to X 8 each independently represents a hydrogen atom or a methylthiol group.
• q represents an integer of 0 to 3
• R 1 represents a simple bond or an alkylene group having 1 to 3 carbon atoms.
• r represents an integer of 0 to 3
• R 2 represents an alkylene group having 1 to 3 carbon atoms.
• Examples of the compound represented by the general formula (1) include 1,5-dimercapto-3-thiapentane, 2-mercaptomethyl-1,5-dimercapto-3-thiapentane, 2,4-bis (mercaptomethyl) -1 , 5-dimercapto-3-thiapentane, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 4,8-bis (mercaptomethyl) -1,11-dimercapto-3,6,9-trithia Undecane, 4,7-bis (mercaptomethyl) -1,11-dimercapto-3,6,9-trithiaundecane, 5,7-bis (mercaptomethyl) -1,11-dimercapto-3,6,9- Examples of the compound represented by the general formula (2) include 2,5-dimercapto-1,4-dithiane and 2,5-dithiane.
• polythiol compounds other than the compounds represented by the general formulas (1) to (3) include ethylene glycol bis (3-mercaptopropionate), trimethiolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (3 -Mercaptopropionate), benzenedithiol, tolylenedithiol and the like.
• the polyisocyanate used as a raw material for the polythiourethane oligomer is a compound having two or more isocyanate groups in one molecule, and may be any of linear, branched, and cyclic.
• polyisocyanates include m-xylylene diisocyanate, 1,3-bis (2-isocyanato-2-propyl) benzene, tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, 1,3-bis (2-isocyanato-2-propyl) cyclohexane, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tris (6-isocyanatohexyl) isocyanurate and the like.
• preferred polyisocyanates are m-xylylene diisocyanate, 1,3-bis (2-isocyanato-2-propyl) benzene, 1,3 -Bis (2-isocyanato-2-propyl) cyclohexane, isophorone diisocyanate.
• the reaction of polythiol and polyisocyanate is, for example, when the product is a dimer, the following reaction formula (In the formula, R and R ′ represent an organic group, and a and b represent an integer of 1 or more.) Proceed according to. Since the thiol group and the isocyanate group react with each other at a ratio of 1: 1, a polythiourethane oligomer having a larger molecular weight is generated as the molar ratio of the thiol group to the isocyanate group is closer to 1.
• the mixing ratio of polythiol and polyisocyanate is preferably in the range of 0.2 to 0.95 mol of isocyanate group, more preferably in the range of 0.4 to 0.95 mol with respect to 1 mol of thiol group. If it is less than 0.2 mol, the conversion rate of the thiol group is too low to be practical, and if it exceeds 0.95 mol, an unreacted isocyanate group remains, which is not preferable.
• the reaction between polythiol and polyisocyanate proceeds by heating in the presence or absence of a catalyst, but a method using a catalyst is preferred.
• a catalyst include tin compounds such as dibutyltin dilaurate and dibutyldichlorotin, and basic compounds such as amine and phosphine.
• the amount of the catalyst used is preferably in the range of 0.01 to 10 parts by weight and more preferably in the range of 0.1 to 1.0 parts by weight with respect to 100 parts by weight of the raw polythiol.
• the reaction between polythiol and polyisocyanate may be performed in the presence of an episulfide compound (component B).
• a solvent may be used as necessary.
• a post-process for distilling off the solvent is required.
• the reaction temperature is not particularly limited, but it is preferably in the range of 0 to 100 ° C. The temperature may be gradually raised while checking the progress of the reaction.
• the reaction time depends on various conditions such as the type of raw material, the mixing ratio of polythiol and polyisocyanate, and the reaction temperature, but cannot be defined unconditionally, but the reaction is continued until no unreacted polyisocyanate remains.
• the curable composition of the present invention includes the polythiourethane oligomer (A component), the episulfide compound (B component), and the photobase generator (C component) described above.
• An episulfide compound (component B) is a compound having one or more episulfide groups in one molecule.
• the following general formula (4) (Wherein, m is an integer from 0 to 6, n is an integer from 0 to 4, each R 3 and R 4 are independently hydrogen atom or an alkyl group having 1 to 10 carbon atoms, R 5 and R 6 is each independently an alkylene group having 1 to 10 carbon atoms.)
• the compound represented by these is preferable.
• Examples of the episulfide compound represented by the general formula (4) include bis (2,3-epithiopropyl) sulfide.
• the episulfide compound represented by the general formula (4) has a large shrinkage due to curing, the shrinkage due to the curing can be suppressed by copolymerizing with the polythiourethane oligomer.
• the episulfide compound represented by the general formula (4) generally has a low viscosity, but is adjusted to a viscosity excellent in workability by mixing with the polythiourethane oligomer.
• the curable composition is used as an adhesive with respect to the viscosity of the curable composition
• the adhesive may sag or flow, or the substrate may be displaced during bonding.
• the viscosity is too high, it is not preferable because it becomes difficult to discharge or apply the adhesive, or bubbles are bitten during the bonding.
• the viscosity suitable for workability as referred to in the present invention depends on the use form of the adhesive such as the coating method and the laminating method, and cannot be defined unconditionally, but is preferably in the range of 500 to 20,000 mPa ⁇ s, more The range is preferably 500 to 10,000 mPa ⁇ s.
• the content of the polythiourethane oligomer is preferably in the range of 10 to 70 parts by weight, more preferably in the range of 20 to 60 parts by weight with respect to 100 parts by weight of the curable composition. If the content of the polythiourethane oligomer is less than 10 parts by weight, the effect of increasing the viscosity or reducing the shrinkage is reduced, and if it exceeds 70 parts by weight, the toughness of the cured product is lowered, which is not preferable.
• the photobase generator (component C) is a compound that generates a base by photolysis with actinic rays.
• amidine such as DBN (diazabicyclononene) and DBU (diazabicycloundecene)
• photobase generators that generate these bases are preferred.
• the amidinium ketone (the left side of the following formula (5)) forming the tetraarylborate salt described in JP-T-2001-513765 and the aryl described in JP-T-2005-511536 1,3-diamine substituted with an alkyl group left side of the following formula (6)
• the addition amount of the photobase generator is preferably in the range of 0.01 to 10 parts by weight, more preferably in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the curable composition.
• Ar 1 is phenyl, biphenyl, naphthyl, phenanthryl, anthracyl, pyrenyl, 5,6,7,8-tetrahydro-2-naphthyl, 5,6,7,8-tetrahydro-1-naphthyl, thienyl, Benzo [b] thienyl, naphtho [2,3-b] thienyl, thiatrenyl, dibenzofuryl, chromenyl, xanthenyl, thioxanthyl, phenoxathiinyl, terphenyl, stilbenyl or fluorenyl, these groups being unsubstituted Or C1-C18
• a photosensitizer may be included. By adding the photosensitizer, the photodecomposition of the photobase generator is accelerated, and the curing time of the photocurable composition can be shortened.
• Specific examples of the photosensitizer include benzophenones, thioxanthones, anthraquinones, camphorquinones, benzyls, Michler ketones, and anthracenes. These may be used alone or in combination of two or more.
• the addition amount of the photosensitizer is preferably in the range of 0.01 to 10 parts by weight and more preferably in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the curable composition.
• a polymerization inhibitor a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a silane coupling agent, a release agent, a pigment, a dye, and the like can be added to the curable composition. . Moreover, you may perform filtration, defoaming, etc. as needed.
• the cure shrinkage rate in an Example was computed from the refractive index before and behind hardening according to the following formula.
• X (1 ⁇ d1 / d2) ⁇ 100 [%]
• the refractive index of M and M represents the molecular weight.
• the viscosity of the curable composition was measured at a temperature of 25 ° C. using a cone / plate viscometer DV-II + (manufactured by Brookfield).
• the refractive indexes of the curable composition and the cured film were measured using an Abbe refractometer NAR-3T (manufactured by Atago Co., Ltd.).
• the transmittance of the cured film was measured using a spectrophotometer U-3500 (manufactured by Hitachi High-Tech) at a thickness of 0.25 mm and a wavelength of 400 nm.
• Example 1 In a 300 ml flask, 25 g of 2,5-dimercaptomethyl-1,4-dithiane, 15 g of m-xylylene diisocyanate and 0.1 g of dibutyltin dilaurate were placed, and stirring was continued at 60 ° C. for 24 hours.
• the curable composition was sandwiched between two release-treated glass plates, irradiated with light from a metal halide lamp (120 W / cm) for 3 minutes from a distance of 30 cm, and then the cured film was peeled from the glass plate.
• a cured film having a thickness of 0.25 mm was produced by the above procedure.
• the physical properties of the curable composition and the cured film were as shown in Table 1.
• Examples 2-5 A curable composition and a cured film were prepared in the same manner as in Example 1 except that the types and amounts of polythiol, polyisocyanate, and episulfide compound were changed to those shown in Table 1.
• the physical properties of the curable composition and the cured film were as shown in Table 1.
• Comparative Example 1 100 g of bis (2,3-epithiopropyl) sulfide, 0.5 g of photobase generator represented by the structural formula (7) (C component), and 4-benzoyl-4′-methyldiphenyl sulfide as a sensitizer 1 g was added and stirred until uniform.
• the curable composition was produced in the above procedure.
• a cured film was produced in the same manner as in Example 1.
• the physical properties of the curable composition and the cured film were as shown in Table 2. In addition, physical properties that are inferior to those of the examples are underlined.

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• Chemical Kinetics & Catalysis (AREA)
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• Polyurethanes Or Polyureas (AREA)
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