JP2005139461A - Photocurable sealant composition and member with sealing layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocurable sealant which suppresses generation of volatile gas from the material cured by UV irradiation; gives low water absorptivity and low hygroscopicity; has high shape retaining properties when applied to an adherend; has an appropriate coating speed so as to maintain mass productivity; realizes cost reduction and high degree of freedom in designing; and ensures stability (shape retaining properties, surface smoothness, etc.) of a cured sealing layer regardless of how the photocurable sealant applied on an adherend is photo-irradiated. <P>SOLUTION: Each component comprises (A) 10-80 wt.% of a urethane (meth)acrylate, (B) 20-90 wt.% of a (meth)acrylate monomer, (C) 0.3-10 wt.% of a photopolymerization initiator, and (D) 1-30 wt.% of a filler. The photocurable sealant composition contains (A)-(D) as the main components and has a yield value in a range of 5-100 Pa (Pascall) of shear stress. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photocurable sealant composition or a method for forming a seal layer using the composition, and more particularly to a sealant for sealing an electronic component case containing an electronic circuit element or electronic component, or a seal therefor The present invention relates to a method for forming a layer.

  Conventionally known photocurable resin compositions include photopolymers such as unsaturated polyester resins, epoxy (meth) acrylates, urethane (meth) acrylates, acrylate resins represented by (meth) acrylate monomers, and the like. What added the polymerization initiator and what added the photoinitiator to the epoxy resin are used. In particular, those using urethane (meth) acrylate are known to be able to be used in various applications because they tend to impart flexibility to the cured product (Japanese Patent No. 2600563).

  These photocurable resin compositions cure rapidly by irradiating with light such as ultraviolet rays, but these cured products have low molecular weight compounds in the cured product even when the light irradiation is complete, for example. There remains a problem that the low molecular weight compound remains and volatilizes from the cured product. This may be due to a low molecular weight unreacted substance or non-reacted substance, an unreacted photopolymerization initiator, a product derived from a photopolymerization initiator decomposed or isomerized by light, or the like.

  On the other hand, there is a great demand and demand for photo-curing resins in the electrical and electronic fields, but in the fields of advanced technology such as high-precision parts and recording media, the generation of low molecular weight compounds from the cured products is corrosive. Cause malfunction. In addition, when using a photo-curing resin as a sealing material or adhesive for magnetic hard disk drives, dust or contaminants due to defective sealing materials may intrude or corrosive substances or contaminants generated from the cured product. A malfunction occurs when recording or reading a signal (Japanese Patent Laid-Open No. 6-105502, Japanese Patent Laid-Open No. 8-72189, Japanese Patent Laid-Open No. 8-74863, etc.). In addition to this, there is a concern that impurities used in the synthesis of the photo-curing resin bleed out impurities (for example, an organic tin compound) to adversely affect the magnetic hard disk drive. Furthermore, in order to use such a photocurable resin as a sealing material, it is also required that the cured product has low water absorption and hygroscopicity and excellent water resistance.

  Therefore, in order to solve such problems, the applicant of the present application previously suppressed generation of volatile gas and bleed out of impurities by Japanese Patent Application Laid-Open No. 6-16749, Japanese Patent Application Laid-Open No. 7-33837, and Japanese Patent Application No. 10-91080. A photocurable resin composition is proposed. Although these inventions are excellent in terms of suppressing volatile gases from cured products and bleeding out impurities, the cured products have high water absorption and hygroscopicity, and are inferior in water resistance. There existed a subject that the thickness as a sealing material was not securable by the shape retention property at the time of apply | coating a composition, ie, the flow with time after application | coating.

  The above shape retention can be solved to some extent by photocuring quickly after applying the photocurable resin composition, but if the coating distance of the sealant is long or the application takes time, the application start position and the application end The height of the seal layer differs depending on the position, resulting in a non-uniform seal layer. Further, when the surface to be coated is not horizontal, the tendency is more remarkable. Therefore, it is conceivable to operate the ultraviolet lamp so as to follow the trajectory of the applied photocurable resin, and to cure by irradiating with ultraviolet rays, but this will increase the cost of the coating irradiation device and increase the cost, Wrinkles are generated on the surface of the cured product of the photocurable resin, and it becomes difficult to obtain a smooth seal layer.

  Therefore, the object of the present invention is to solve the above-mentioned problems, that is, to suppress the generation of volatile gas from a cured product cured by ultraviolet irradiation, and has low water absorption and moisture absorption, and is applied to an adherend. It has high shape-retaining ability, maintains mass productivity by having an appropriate application speed, can reduce cost and give design freedom, and can be used for the photo-curable sealant applied to the adherend. It is an object of the present invention to provide a photocurable sealing agent that can ensure the stability (shape retention property, surface smoothness, etc.) of a cured seal layer even when light is irradiated by such a method, and a member to which the seal layer is attached. .

In order to solve the above-mentioned problems, (A) urethane (meth) acrylate 10 to 80% by weight
(B) (meth) acrylic acid ester monomer 20 to 90% by weight
(C) Photopolymerization initiator 0.3 to 10% by weight
(D) Filler 1-30% by weight
A composition comprising the above (A) to (D) as a main component, and the composition having a yield value in the range of shear stress 5 to 100 Pa (Pascal). It was a thing. Further, the sealing layer formed with this composition was cured by light irradiation so that the cross-sectional shape of the sealing layer was 0.5 to 0.9 with respect to the width 1, thereby obtaining a member with a sealing layer.

The photocurable sealant composition of the present invention generates little outgas and impurities from the cured product and has little influence on the surroundings. The effect is particularly remarkable in a system using polyether urethane (meth) acrylate and a system using a high molecular weight photopolymerization initiator.
In addition, when silica powder that has been subjected to hydrophobic treatment is used, a composition having higher shape retention can be obtained, and the height / width ratio of the sealing layer can be kept high, so that the effect as a sealing agent is greater. In particular, the effect of the silica powder treated with polydimethyl silicone oil is remarkable. Furthermore, because it has properties (viscoelasticity) suitable for application using an automatic application machine, it can be applied without being affected by the shape or size of the adherend, so the design of the adherend is free. The degree is increased.

Since the photocurable sealant composition of the present invention is applied to an adherend and does not easily shift or flow without being cured by light irradiation, it can be easily moved, and therefore the light irradiation process is summarized. It is excellent in productivity.
The present invention will be described in detail with reference to examples. The following examples show only one form of the present invention, and the present invention is not limited to them.

Examples of (A) urethane (meth) acrylate that can be used in the present invention include polycarbonate urethane (meth) acrylate as disclosed in JP-A-5-70535 and bisphenol A as disclosed in JP-A-6-301206. Urethane (meth) acrylate obtained by adding ethyl isocyanate (meth) acrylate or the like to alcohol chain-extended with polyethylene glycol or the like, or (meth) acrylate-modified perfluoropolyether urethane prepolymer as disclosed in JP-A-10-237392. Examples thereof include urethane (meth) acrylate obtained by adding a (meth) acrylate having an active hydrogen group to a polymer, a reaction product of a polyether polyol or polyether diol and an organic diisocyanate compound. Among these, a urethane prepolymer obtained by mixing and reacting a polyether polyol or polyether diol and an organic diisocyanate compound in a molar ratio of 1: 1 to 1: 2 in a diluent is further added to the urethane prepolymer. A compound obtained by reacting the remaining isocyanate group of the polymer with a (meth) acrylic acid ester monomer having a sufficient amount of active hydrogen groups to react with the isocyanate group is preferred.
Specific examples of the polyether polyol and polyether diol include a polyol compound or diol compound having a bisphenol A skeleton in the molecule as described in Japanese Patent No. 2568421 and having a hydroxyl group at the terminal or side chain. And a polyol compound or a diol compound having an ethylene oxide or propylene oxide structure in the molecule. These polyether polyols and polyether diols are used alone or in combination. Among these compounds, a polyether polyol compound or a polyether diol compound having a bisphenol A skeleton and an ethylene oxide structure in the molecule is particularly preferable from the viewpoint of photocurability, water absorption, and outgas.

  Examples of the organic diisocyanate compound include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), xylene diisocyanate (XDI), isophorone diisocyanate (IPDI), naphthylene diisocyanate (NDI), tolidine diisocyanate (TPDI), Hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), trimethylhexamethylene diisocyanate (TMHDI) and the like can be mentioned, and these are used alone or in combination. Among these, hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), and trimethylhexamethylene diisocyanate (TMHDI) are preferable from the viewpoints of photocurability, water absorption, and outgas.

  Examples of the (meth) acrylate monomer having an active hydrogen group include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol. Mono (meth) acrylates of divalent alcohols, mono (meth) acrylates or di (meth) acrylates of trivalent alcohols such as trimethylol ethane, trimethylol propane, glycerin, etc. Can be used.

  The average molecular weight of the (A) urethane (meth) acrylate obtained as described above is preferably 1,000 to 100,000, and more preferably 5,000 to 50,000. If the average molecular weight exceeds 100,000 in terms of MW, the viscosity is too high, so that application by a coating machine becomes difficult and workability deteriorates. If it is less than 1,000, the cured product becomes hard and lacks flexibility.

  In addition, the polymerization catalyst used in the synthesis of (A) urethane (meth) acrylate is not particularly limited as long as it is a conventionally known catalyst, but the generation of outgas from the cured product of the photocurable sealing agent composition In view of impurity bleed-out, organic zinc or an amine compound is preferable. Specific examples of organic zinc include zinc salt compounds of carboxylic acids such as zinc octenoate and zinc 2-ethylcaproate, triethylamine, dimethylcyclohexylamine, tetramethylethylenediamine, pentamethyldiethylenetriamine, pentamethyldipropylenediamine, and tetramethylguanidine. , Triethylenediamine, N-methylmorpholine, 1,2-dimethylimidazole, dimethylaminoethanol, dimethylaminoethoxyethanol, trimethylaminoethylethanolamine, (2-hydroxyethyl) morpholine etheramine, N-methylpiperazine, N, N ' -Amine compounds such as dimethylpiperazine and N-endoethylenepiperazine.

  The (B) (meth) acrylic acid ester monomer that can be used in the present invention is a (meth) acrylic acid ester monomer having at least one cyclic structure in the molecule, specifically, for example, isobornyl (meth) acrylate, Cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, phenoxy (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, dicyclopentadiene Di (meth) acrylates and the like can be mentioned, but phenoxy (meth) acrylate and tetrahydrofurfuryl (meth) acrylate are preferable, and the glass transition point has low water absorption, high reactivity, or a cyclic structure. (T ) From phenoxy (meth) acrylate such as a low point are particularly preferred. The molecular weight of these (meth) acrylic acid ester monomers is preferably 1,000 or less.

  Examples of the (C) photopolymerization initiator that can be used in the present invention include acetophenone, diethoxyacetophenone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1, benzoin, benzoin ethyl ether, Examples include, but are not limited to, benzyl dimethyl ketal, benzophenone, benzyl, methyl benzoyl formate, thioxanthone, diethyl thioxanthone, and conventionally known photopolymerization initiators can be used. In particular, 2-hydroxy-2-methyl-1-phenylpropan-1-one (trade name DAROCURE 1173 manufactured by Ciba Geigy) as exemplified in JP-A-7-33837, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone (trade name IRGACURE 2959 Ciba Geigy), 4- (2-acryloyloxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl-phenylketone (Product name: IRGACURE 184, manufactured by Ciba Geigy), 1- (4-Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropane -1-one, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one (trade name, IRGACURE 907 manufactured by Ciba Geigy), 2-benzyl-2-dimethylamino-1- (4-morpholino) Phenyl) -butanone (trade name IRGACURE 369 Ciba Geigy ), 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propane oligomer (trade name, manufactured by ESACURE KIP 150 Lamberti), etc. Generation of gas can be suppressed, and an oligomer of 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propane is particularly preferable because of its large effect.

  As the filler (D) that can be used in the present invention, an inorganic filler such as silica powder can be preferably used. The fine powder silica is fine powder silica having an average primary particle diameter of 1 to 100 nm, preferably 5 to 50 nm. Specifically, when hydrolyzing silicon tetrachloride in an acid hydrogen bath, titanium chloride is used. In addition, fine powdered silica such as alumina-containing silica, titanium oxide-containing silica, iron oxide-containing silica can be mentioned by coexisting chlorides such as aluminum chloride and iron chloride. Particularly, the surface of hydrophilic fine powder silica is treated with hydrophobic treatment. Are preferably used.

Hydrophobic fine-powdered silica is a surface of normal hydrophilic fine-powdered silica such as n-octyltrialkoxysilane and other alkyl, aryl, aralkyl silane coupling agents, dimethyldichlorosilane, hexamethyldisilazane and other silyls. It can be obtained by treating with a hydrating agent, polydimethylsiloxane having a hydroxyl group at the end, higher alcohol such as stearyl alcohol, higher fatty acid such as stearic acid. Can be used.
1) AEROSIL-R972, R974, R976 (made by Nippon Aerosil Co., Ltd.) as treated with dimethyldichlorosilane
2) AEROSIL-RX50, NAX50, NX90, RX200, RX300 (made by Nippon Aerosil Co., Ltd.) as treated with hexamethyldisilazane
3) AEROSIL-R805 (manufactured by Nippon Aerosil Co., Ltd.) as treated with octylsilane
4) AEROSIL-RY50, NY50, RY200S, R202, RY200, RY300 (above Nippon Aerosil Co., Ltd.), CAB ASIL TS-720 (CABOT Co., Ltd.) treated with dimethyl silicone oil
In addition to this, hydrophobic fine powder silica subjected to the same treatment is commercially available from several companies. The fine powder silica may be used alone or in combination of two or more. Among these, silica powder surface-treated with polydimethylsiloxane is particularly preferable because it can impart moderate thixotropy and viscosity, that is, ease of application and shape retention, to the photocurable sealant composition of the present invention.

  The blending ratio of each component (A) to (D) described above is (A) urethane (meth) acrylate 10 to 80% by weight, preferably 20 to 60% by weight, (B) (meth) acrylic acid ester monomer 20 to 20%. 90% by weight, preferably 40 to 80% by weight, (C) a photopolymerization initiator 0.3 to 10% by weight, and (D) a filler 1 to 30% by weight, preferably 3 to 20% by weight.

  (A) If the added amount of urethane (meth) acrylate is more than 80% by weight, the composition becomes too viscous and application by a coating machine becomes difficult and workability is reduced, and if it is less than 10% by weight, the composition is cured. Things become hard and lack flexibility. (B) If the added amount of (meth) acrylic acid ester monomer is more than 90% by weight, the cured product becomes hard and lacks flexibility, and if it is less than 20% by weight, the composition becomes too viscous to be applied by a coating machine. It becomes difficult and workability deteriorates. (C) When the amount of the photopolymerization initiator is more than 10% by weight, the storage stability of the composition is lowered, the physical properties of the cured product are lowered, or the generation of outgas is increased. On the other hand, if it is less than 0.3% by weight, the photocurability is lowered. (D) When the added amount of the filler exceeds 30 parts by weight, the composition may become too viscous to be applied by an applicator or the surface smoothness of the applied sealant may be lost. When the amount is less than 1 part by weight, the shape retention of the sealing agent when applied is lowered and the fluid tends to flow. Therefore, it becomes difficult to form a thick seal layer.

The photocurable sealing agent composition of the present invention can be produced by mixing the above-described components (A) to (D) by an ordinary method, but at this time, the composition is mixed and stirred in a state where it is shielded from light. In addition, it is desirable that the stirring be performed in a vacuum so as not to entrap bubbles.
The photocurable sealing agent composition of the present invention is applied to a flange portion of an adherend such as an electronic component, and then cured by irradiation with light, whereby the cured product forms a seal layer having rubber elasticity. Functions as a material. In this case, since it adheres firmly to the flange portion of the adherend, it can be used as an adhesive or a surface coating agent in addition to being used as a sealing material. In particular, it can be bonded to many materials such as metal, plastic, glass, or an adherend on which these are coated, and among them, adhesion to a metal or a metal-plated material is good.

  In addition, the photocurable sealant composition of the present invention is particularly used for a member having a sealing layer having rubber elasticity by being applied to a flange surface of a member requiring sealing and being photocured. Although suitable, this is because of the moderate viscosity and thixotropy of the photocurable sealant composition of the present invention, that is, the application stability (quantitative and shape) of the sealant when applied to the flange portion, It is because it is excellent in the shape maintenance property which maintains the shape as apply | coated until photocuring. In addition, after apply | coating a photocurable sealing agent composition to a to-be-adhered body, a small amount of light can be irradiated and it can be made to harden | cure to a semi-gelled state, and shape retention property can also be improved. Furthermore, the photocurable sealant composition of the present invention is most effective for light including an ultraviolet range emitted from a conventionally known light source such as a mercury lamp or a xenon lamp, but has an absorption wavelength for visible light, for example. If a photopolymerization initiator is used, curing with visible light is also possible.

  Examples of the coating apparatus that can be used in the present invention include conventionally known automatic coating apparatuses. These automatic coating apparatuses include a robot unit having an arm unit that can move three-dimensionally, a nozzle unit that discharges material fixed to the arm unit, a material supply unit that supplies material to the nozzle unit, and these Generally, it is comprised from the control part which controls. In order to apply the photocurable sealant composition of the present invention using such an automatic application device, the inner diameter of the nozzle portion for discharging the material should be set to 0.1 to 2.0 mm (preferably 0.5 to 1.2 mm). The discharge pressure is preferably in the range of 0.001 to 0.05 MPa (preferably 0.005 to 0.02 MPa), and the coating speed is preferably 1 to 100 mm / sec (preferably 10 to 30 mm / sec). At this time, the height / width ratio of the seal layer applied and formed on the adherend is preferably 0.5 or more with respect to the width 1. By using such a coating device, for example, a sealing layer having a coating width of about 2.0 mm or less suitable for hermetic sealing of a magnetic recording device (hard disk) can be easily formed.

  Furthermore, the photocurable sealant composition of the present invention desirably has a yield value (yield stress) in the range of shear stress (Shear stress) of 1 to 100 Pa (Pascal). By performing such a limitation, the photocurable sealing agent composition of the present invention starts to flow (apply) at a relatively low discharge pressure (shear stress), and immediately after the discharge pressure is removed, the original state It means to recover to (specific viscosity and thixotropy) and lose fluidity. If this characteristic (viscoelasticity) is expressed by another expression, it can be shown in Tables 4-8.

  The shear stress and the yield value of the stress are measured using a stress control type rheometer DAR-100 (manufactured by REOLOGICA). This measuring apparatus sandwiches a sample (photocurable sealing agent composition) between two plates (A, B) using a measuring jig as shown in FIG. The viscoelastic properties (rheology) of the sample are measured by applying an external force. The measurement condition at this time is a gap of 1.0 mm between the movable plate A (diameter 25 mm) and the fixed plate B shown in FIG. After the sample was filled, the external force in the rotational direction was varied with respect to the axis of the movable plate A (variable angular velocity, temperature 25 ° C., frequency 0.0016 Hz to 16.0 Hz).

(Synthesis Example 1) Synthesis of urethane (meth) acrylate:
Polyethylene diol represented by the structural formula (1) 1.9 mol, hexamethylene diisocyanate (HDI) 2.0 mol, and butylhydroxytoluene as a polymerization inhibitor (0.4 wt% based on the total weight of the mixture of BHT polyether diol and HDI) And tetrahydrofurfuryl acrylate as a diluent (added by 20% by weight in the total weight ratio of the mixture of polyether diol and HDI), and 0.01% by weight of octyl zinc is used as a catalyst for this mixture. The resulting mixture was reacted at 80 ° C. for 2 hours to obtain a prepolymer having an isocyanate group at the terminal.
Next, 4.0 mol of 2-hydroxyacrylate (2-HEA) was added and stirred at 80 ° C. for 2 hours to synthesize a urethane (meth) acrylate having an acryloyl group at the terminal. As a result of measurement by GPC, the average molecular weight of this urethane prepolymer was about MW 50,000 and the degree of dispersion was 3.0.

nは１〜５の整数を、Phはベンゼン環をそれぞれ表す。

n represents an integer of 1 to 5, and Ph represents a benzene ring.

(Synthesis Example 2)
4.0 mol of hexamethylene diisocyanate (HDI) is added to 3.0 mol of the polyether diol used in Synthesis Example 1, butylhydroxytoluene (0.4 wt% based on the total weight of the mixture of BHT polyether diol and HDI) as a polymerization inhibitor, and dilution In the presence of tetrahydrofurfuryl acrylate as an agent (20% by weight in the total weight ratio of the mixture of polyether diol and HDI), 0.01% by weight of octyl zinc is added to the mixture as a catalyst, The mixture was reacted at 80 ° C. for 2 hours to obtain a prepolymer having an isocyanate group at the terminal. Next, 4.0 mol of 2-hydroxyacrylate (2-HEA) was added and stirred at 80 ° C. for 2 hours to synthesize a urethane (meth) acrylate having an acryloyl group at the terminal. As a result of measurement by GPC, the average molecular weight of this urethane prepolymer was about MW 8,000, and the degree of dispersion was 1.7.

(Examples 1-8)
A photocurable sealing agent composition was produced at the blending ratio shown in Table 1, and each produced composition was evaluated based on the following evaluation test methods. The results are shown in Table 1.
In addition, each evaluation test was implemented with the following method.
1. Outgas test: 1 g of the cured product was stored in a high-temperature bath at 80 ° C. for 24 hours, and the change in weight was measured.
2. Water absorption test: 1 g of the cured product was immersed in boiling water at 100 ° C. for 2 hours, and the water absorption was measured.
3. Applicability test: Using TSR-50 type automatic applicator (manufactured by ThreeBond Co., Ltd.), the applicability when the nozzle inner diameter is 1.0 mm, the pressure is 0.01 to 0.015 MPa, and the nozzle moving speed is 20 mm / sec. Confirmed.
4). Shape retention: The photocurable sealant composition applied to the adherend by the applicator described in 3 above is allowed to stand at 25 ° C. for 2 hours and then photocured to measure the height / width of the cured product (seal layer). did.
5). Surface smoothness after curing: The surface smoothness after photocuring the photocurable sealing agent composition (25 ° C. × 1 h standing) applied to the adherend in the above 4 was visually confirmed.
6). Rubber properties of cured product: The rubber elasticity of the cured product of 5 above was confirmed by finger touch.
7). Preservability test: The state after storing the compounded photocurable sealing agent composition at room temperature for 1 week was observed.

＊１ 合成例１及び２のウレタンアクリレートはテトラヒドロフルフリルアクリレートを20重量％含有する。
＊２ ポリエステルウレタンアクリレート 根上工業社製
＊３ Lamberti社製光重合開始剤
＊４ Ciba Geigy社製光重合開始剤

* 1 The urethane acrylates of Synthesis Examples 1 and 2 contain 20% by weight of tetrahydrofurfuryl acrylate.
* 2 Polyester urethane acrylate manufactured by Negami Kogyo Co., Ltd. * 3 Photopolymerization initiator manufactured by Lamberti * 4 Photopolymerization initiator manufactured by Ciba Geigy

  According to the results in Table 1, polyether urethane acrylate can suppress outgassing more than polyester urethane acrylate. Further, when a high molecular weight photopolymerization initiator is used, outgas can be further reduced. Since the average molecular weight 50,000 polyether urethane acrylate has a higher viscosity than that of an average molecular weight of 8,000, a decrease in the coating amount is observed under the same coating conditions. In other words, the coating speed becomes slow, and it is necessary to increase the discharge pressure in order to ensure the same coating amount.

(Examples 9 to 14, Comparative Examples 1 and 2)
A photocurable sealing agent composition was produced at the blending ratio shown in Table 2, and each produced composition was evaluated based on the following evaluation test methods. The results are shown in Table 2.

−は未測定を表す。

-Represents unmeasured.

According to the results in Table 2, it can be seen that when a (meth) acrylic acid ester monomer having at least one cyclic structure in the molecule is used, favorable results are exhibited in outgassing properties and water absorption.
(Examples 15 to 19, Comparative Examples 3 and 4)
Photocurable sealant compositions were produced at the blending ratios shown in Table 3, and the produced compositions were evaluated based on the following evaluation test methods. The results are shown in Table 3.

＊１ ノズル先端より液ダレ発生。
＊２ 粘度が高すぎて塗布不能。
＊３ 初期の３倍以上に増粘した。
−は、未測定を表す。

* 1 Liquid dripping occurs from the nozzle tip.
* 2 The viscosity is too high to be applied.
* 3 Thickened more than three times the initial.
-Represents unmeasured.

According to the results in Table 3, the silica powder subjected to hydrophobic treatment has both good shape retention and storage stability, and among them, those treated with polydimethylsiloxane are particularly excellent in shape retention.
Moreover, the result of having measured the viscoelasticity of the composition of Example 15 and 16 was shown to FIGS. At the time of measurement, the compositions of Examples 15 and 16 were set in the stress-controlled rheometer DAR-100 (manufactured by REOLOGICA) and stirred for 10 seconds at 10 (1 / s). Measurements were taken immediately after standing for 100 seconds. Detailed conditions are as follows.
Stree: 13 points were measured at 0.0016-16 Hz.
Continuous on Strain 1.00E-3 Time1179.3s

FIG. 2 is a graph showing the relationship between the shear stress (Shear stress Pa) and the storage elastic modulus (G′k Pa). It can be seen from the graph of FIG. 2 that the composition of Example 16 has a stable storage modulus over a wider range of shear stress.
FIG. 3 is a graph showing the relationship between shear stress (Shear stress Pa) and viscosity. From the graph of FIG. 3, the composition of Example 15 is around 12 Pa, and the composition of Example 16 is around 50 Pa. It can be seen that it has a yield value (yield stress).

FIG. 4 is a graph showing the relationship between the angular velocity (Omega rad / s) and the storage elastic modulus (G′k Pa). In particular, the composition of Example 16 is stable when the value of the storage elastic modulus is around 1. From this, it can be seen that the stability during application is excellent.
FIG. 5 is a graph showing the relationship between the angular velocity (Omega rad / s) and the loss tangent (Tan phase). In the composition of Example 16, the loss tangent is in the range of 0.01 to 10 (rad / s). It can be seen that it is closer to a non-fluid because it is lower than that of the composition of FIG.
FIG. 6 is a graph showing the relationship between the angular velocity (Omega rad / s) and the viscosity. It can be seen that the viscosity decreases as the angular velocity increases.

It is a partial enlarged view of the apparatus used for the measurement of the shear stress. FIG. 2 is a graph showing the relationship between shear stress (Shear stress Pa) and storage elastic modulus (G′k Pa) from the results of measuring the viscoelasticity of the compositions of Examples 15 and 16. In the figure, the point ● represents the composition of Example 15, and the point ◯ represents the composition of Example 16. FIG. 3 is a graph showing the relationship between shear stress (Shear stress Pa) and viscosity from the results of measuring the viscoelasticity of the compositions of Examples 15 and 16. In the figure, a ■ point represents the composition of Example 15, and a □ point represents the composition of Example 16.

FIG. 4 is a graph showing the relationship between the angular velocity (Omega rad / s) and the storage elastic modulus (G′k Pa) from the results of measuring the viscoelasticity of the compositions of Examples 15 and 16. The dot represents the composition of Example 15, and the dot represents the composition of Example 16. FIG. 5 is a graph showing the relationship between the angular velocity (Omega rad / s) and the loss tangent (Tan phase) from the results of measuring the viscoelasticity of the compositions of Examples 15 and 16. The dot represents the composition of Example 15, and the dot represents the composition of Example 16. FIG. 6 is a graph showing the relationship between the angular velocity (Omega rad / s) and the viscosity based on the results of measuring the viscoelasticity of the compositions of Examples 15 and 16. The dot represents the composition of Example 15, and the dot represents the composition of Example 16.

Explanation of symbols

1 Photo-curable sealant composition (uncured)
A Movable plate B Fixed plate

Claims (9)

(A) Urethane (meth) acrylate 10-80% by weight
(B) (meth) acrylic acid ester monomer 20 to 90% by weight
(C) Photopolymerization initiator 0.3 to 10% by weight
(D) Filler 1-30% by weight
It is a composition having the above (A) to (D) as main components, and the composition has a yield value (yield stress) in the range of shear stress (Shear stress) 5 to 100 Pa (Pascal). A photocurable sealant composition characterized by the above.   The (A) urethane (meth) acrylate is a reaction product of a polyether diol, a polyether polyol or a mixture thereof and an organic diisocyanate compound, and a (meth) acrylic acid ester monomer having a hydroxyl group in the molecule. The photocurable sealing agent composition according to claim 1, which is a polyether urethane (meth) acrylate compound obtained by polymerization.   The photocurable sealing agent composition according to claim 2, wherein the polyether diol or polyether polyol or a mixture thereof has a bisphenol skeleton in the molecule.   The photocurable sealing agent composition according to claim 1, wherein the (A) urethane (meth) acrylate has an average molecular weight of 1,000 to 100,000.   The photocurable sealant composition according to claim 1, wherein the (B) (meth) acrylic acid ester monomer has at least one cyclic structure in its molecular structure.   The photocurable sealing agent according to claim 1, wherein the (B) (meth) acrylic acid ester monomer has a molecular weight of less than 1,000.   The photocurable sealing agent according to claim 1, wherein the photopolymerization initiator (C) is an oligomer of 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propane.   The photocurable sealing agent according to claim 1, wherein the filler (D) is obtained by subjecting the surface of silica powder to a hydrophobic treatment. (A) Urethane (meth) acrylate 10-80% by weight
(B) (meth) acrylic acid ester monomer 20 to 90% by weight
(C) Photopolymerization initiator 0.3 to 10% by weight
(D) Filler 1-30% by weight
A photocurable sealant comprising the above (A) to (D) as a main component, wherein the composition has a yield value in the range of shear stress 5 to 100 Pa (Pascal). It is applied to an adherend, and cured by light irradiation so that the cross-sectional shape of the applied photocurable sealing agent cured product (seal layer) is 0.5 to 0.9 with respect to a width of 1. A member with a sealing layer.

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