JPH0948830A - Ultraviolet-curable flexible potting composition and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject flexible and transparent composition excellent in touch feeling, capable of easily controlling its flexibility, and rapid in curing rate, by reaction between a specific polyurethane acrylate, a reactive diluent and a photopolymerization initiator. SOLUTION: This composition is obtained by reaction between (A) pref. 25-65wt.% of a polyurethane acrylate with an average functional group number (f) satisfying the relationship: 2<(f)<=2.5 (pref. 1000-5000 in number-average molecular weight and 1.4-3.6mmol/g in urethane group concentration), (B) pref. 40-75wt.% of a reactive diluent having polymerizable double bond (e.g. tetrahydrofurfuryl acrylate) and (C) pref. 0.5-5 pts.wt., based on a total of 100 pts.wt. of the components A and B, of a photopolymerization initiator (pref. 1-hydroxycyclohexyl phenyl ketone). It is preferable that the polyol component to be used for producing the component A be a combination of a polyether polyol 200-4000 in molecular weight with a polyol 62-200 in molecular weight.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ultraviolet-curable soft potting composition and a method for producing the same, and more particularly to an ultraviolet-curable soft potting composition used for potting decorative parts such as automobiles and a method for producing the same.

[0002]

2. Description of the Related Art Potting resins used for decorative insignia and the like are currently coated with a thick film on a base material to give a further volume feeling and depth due to a lens effect. It is applied to light electrical appliances, sundries, emblems for automobile interior and exterior parts, marks, stickers, touch switches, etc.

As these potting resins, two-component curing type polyurethane resins having excellent weather resistance and durability have been used conventionally.

However, the above-mentioned two-component curing type polyurethane resin has problems that it is not easy to handle and that it takes a long time to cure since the two components must be mixed at the time of use.

On the other hand, in recent years, energy saving, workability improvement,
Due to reasons such as improved productivity, UV-curable resin compositions have come to be widely used, and UV-curable resins have been proposed as potting agents (Japanese Patent Laid-Open Publication No. 6-68242).
3-86714).

In the invention described in the above publication, the potting composition is polyurethane acrylate,
It has been proposed to use a bisphenol-type epoxy acrylate, a hydroxyl group-containing (meth) acrylate, and an acrylamide-containing one. As effects of the invention, a high curing speed of the potting composition, and a thick film It is mentioned that it can be cured with, that the cured film is transparent, and that it has excellent bendability and toughness.

[0007]

However, since the polyurethane synthesized by the reaction of diol and diisocyanate is used as the raw material of the polyurethane acrylate contained in the potting composition, the number of functional groups is fixed to 2. It When such a polyurethane acrylate having 2 functional groups is used, the ultraviolet curability is not so good, and there is a problem that it is not easy to adjust the softness while maintaining the toughness of the cured product. .

Further, in the above-mentioned invention, since acrylamide is used as a polymerization initiation aid or a diluent, there is a problem that the weather resistance is not so good and yellowing easily occurs.

The present invention has been made in view of the above problems, and the cured product is soft (JIS-A hardness: 50 to 50).
80), its softness can be easily adjusted, its curability is fast, it is transparent and flexible, and it has heat resistance, water resistance, wet heat resistance, warm water resistance, detergent resistance, cold heat cycle and weather resistance, etc. It is an object of the present invention to provide an ultraviolet-curable soft potting composition excellent in various properties and its manufacturing method.

[0010]

In order to achieve the above object, the ultraviolet-curable soft potting composition according to the present invention has an average number of functional groups (f) in the molecule (A) of 2.0 <f ≦.
Polyurethane acrylate in the range of 2.5, (B)
It is characterized by reacting a reactive diluent having a polymerizable double bond and (C) a photopolymerization initiator (1).

The ultraviolet-curable soft potting composition according to the present invention has the hardness (JIS-A) of 5 in the ultraviolet-curable soft potting composition described in (1) above.
It is characterized by being 0 to 80 (2).

The ultraviolet-curable soft potting composition according to the present invention is the ultraviolet-curable soft potting composition as described in (1) or (2) above, wherein the concentration of urethane groups in the polyurethane acrylate is 1.4 to 3. 0.6 mm
It is characterized by being ol / g (3).

The ultraviolet-curable soft potting composition according to the present invention is the ultraviolet-curable soft potting composition according to the above (1) to (3), wherein the polyurethane acrylate has an ether group in the molecule, It is characterized in that a polyether polyol having a molecular weight of 200 to 4000 and a low molecular weight polyol having a molecular weight of 62 to 200 are used as raw materials (4).

The UV-curable soft potting composition according to the present invention is the same as the UV-curable soft potting composition described in (1) to (4) above, except that 25 to 60% by weight of a polyurethane acrylate and a polymerizable double layer are used. It is characterized in that 0.5 to 10 parts by weight of a photopolymerization initiator is added to 100 parts by weight of an ultraviolet curable component composed of 40 to 75% of a reactive diluent having a bond (5).

Further, the method for producing an ultraviolet-curable soft potting composition according to the present invention comprises (A) a polyurethane acrylate having an average number of functional groups (f) in the molecule of 2.0 <f ≦ 2.5, The viscosity at 25 ° C. containing the reactive diluent having a polymerizable double bond (B) and the photopolymerization initiator (C) is 300 to 5000 mPa.s. The uncured potting composition of No. s is characterized by being pre-cured by a near-ultraviolet lamp, low-ultraviolet fluorescent lamp, low-pressure mercury lamp or the like, and then finally cured by a high-pressure mercury lamp or a metal halide lamp.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION First, it is used as a raw material for an ultraviolet-curable soft potting composition according to the present invention (A).
A polyurethane acrylate having an average number of functional groups (f) in the range of 2.0 <f ≦ 2.5 will be described.

The polyurethane acrylate (A) used in the present invention is obtained, for example, by subjecting an organic polyisocyanate, a polyol and a hydroxyl group-containing acrylate to a urethanization reaction according to a conventional method.

The polyol used for producing the polyurethane acrylate has a molecular weight of, for example, 200 to
4000 polyether polyol, molecular weight 62-2
00 low molecular weight polyol, polyester polyol,
Examples thereof include polyether ester polyol, polyester amide polyol, polycarbonate polyol, polyhydroxyalkane, castor oil, and polyurethane polyol.

The polyether polyol has a molecular weight of 2
When it is less than 00, the molecular weight of the obtained polyurethane acrylate becomes too small, so that the cured product tends to be hard, while the polyether polyol has a molecular weight of 40.
On the other hand, if it exceeds 00, the molecular weight of the polyurethane acrylate obtained may become too large, and the cured product may become too soft. The low molecular weight polyol has a molecular weight of 2
If it exceeds 00, it tends to be difficult to adjust the molecular weight even if a low molecular weight polyol is added to the polyether polyol. Further, the average number of functional groups (f) is 2.0 <f
In order to adjust to ≦ 2.5, it is preferable to use the low molecular weight polyol having a valence of 3 or more.

The polyether polyol is a compound having an ether group in the molecule and two or more OH groups at the terminal. Specific examples of the polyether polyol include polyethylene glycol and polyoxy. Examples thereof include propylene glycol, polytetramethylene ether glycol, a copolymer of propylene oxide and ethylene oxide, a copolymer of tetrahydrofuran and propylene oxide, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A. In the present specification, the polyol means an alcohol having two or more OH groups.

Commercially available products of these polyether polyols include polyethylene glycols such as "PEG 600" and "PEG 100" manufactured by Sanyo Kasei Co., Ltd.
0 "," PEG 2000 "and the like. Examples of polypropylene glycol include" PPG diol 1000 "and" PPG diol 2 "manufactured by Mitsui Toatsu Chemicals, Inc.
000 ”,“ PPG diol 3000 ”,“ EXCENOL 1020 ”,“ EXCENOL 20 ”manufactured by Asahi Glass Co., Ltd.
20 "," Exenol 3020 "and the like,
Examples of the polytetramethylene ether glycol include “PTG 650” and “PTG 85” manufactured by Hodogaya Chemical Co., Ltd.
0 "," PTG 1000 "," PTG 2000 ",
Examples of the copolymer of propylene oxide and ethylene oxide include "ED-28" manufactured by Mitsui Toatsu Chemical Co., Inc., "EXCENOL 510" manufactured by Asahi Glass Co., Ltd., and tetrahydrofuran and propylene. Examples of oxide copolymers include "PPTG1000" and "PPTG" manufactured by Hodogaya Chemical Co., Ltd.
2000 "," PPTG 4000 "," Unisafe DCB-1100 "manufactured by NOF Corporation," Unisafe D "
CB-1800 "and the like, and examples of copolymers of tetrahydrofuran and ethylene oxide include" Unisafe DC-1100 "and" Unisafe DC-1800 "manufactured by NOF Corporation, and ethylene oxide adducts of bisphenol A. For example, "UNIOR DA-400", "UNIOR" manufactured by NOF CORPORATION
DA-700 "and the like, and examples of the propylene oxide adduct of bisphenol A include" UNIOL DB-400 "manufactured by NOF CORPORATION.

Of these, polytetramethylene ether glycol is preferable because it can provide a potting composition having excellent adhesion to a substrate and excellent physical properties such as water resistance. The average molecular weight of polytetramethylene ether glycol is preferably 250 to 4000,
Those of 0 to 2000 are more preferable.

Specific examples of the above-mentioned low molecular weight polyol having a molecular weight of 62 to 200 include, for example, glycols such as ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, dipropylene glycol, hexylene glycol, neopentyl glycol and cyclohexanedimethanol. Kinds; glycerin, trimethylolpropane, pentaerythritol and the like can be mentioned.

Specific examples of the polyester polyol include dibasic acids such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid and sebacic acid, dialkyl esters of the dibasic acids or mixtures thereof, and ethylene glycol, for example. Propylene glycol, butylene glycol, diethylene glycol, neopentyl glycol, 1,6-hexane glycol, 3-methyl-
Polyester polyols obtained by reacting with glycols such as 1,5-pentanediol, 3,3′-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol or mixtures thereof; poly Caprolactone, polyvalerolactone, poly (β-methyl-γ
-Valerolactone) and other polyester polyols obtained by ring-opening polymerization of lactones.

Specific examples of the polyether ester polyol include dibasic acids such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid and sebacic acid, dialkyl esters of the dibasic acids or a mixture thereof, and the polyester. Examples thereof include polyether ester polyols obtained by reacting with a polyol.

Specific examples of the polyesteramide polyol include, for example, a fat having an amino group such as ethylenediamine, propylenediamine and hexamethylenediamine in the polyesterification reaction for obtaining the above-mentioned polyesterpolyol or the polyetheresterpolyol. Examples thereof include those obtained by reacting a group diamine with the above raw materials.

Specific examples of the polycarbonate polyol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and 3-methyl. -1,5-pentanediol,
1,9-nonanediol, 1,8-nonanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol,
1,4-cyclohexanedimethanol, bisphenol A, and one or more glycols selected from hydrogenated bisphenol A, for example, dimethyl carbonate, diphenyl carbonate, ethylene carbonate,
Examples thereof include those obtained by the reaction with phosgene and the like.

Examples of the polyhydroxyalkane include butadiene and liquid rubber obtained by copolymerizing butadiene and acrylamide.

The polyurethane polyol is a polyol having a urethane bond in one molecule, and the polyurethane polyol has, for example, the above-mentioned molecular weight of 2
00-5000 polyether polyol, the polyester polyol, the polyether ester polyol, etc., and an organic polyisocyanate described later (NCO
/ OH) and the like, which are obtained by reacting at a molar ratio of less than 1, preferably 0.9 or less.

These polyols can be used alone or in combination of two or more.

Of these, polyether polyols having a molecular weight of 200 to 4000 are preferable from the viewpoints of lowering the viscosity of urethane acrylate and adhering to a substrate, and controlling the molecular weight of urethane acrylate to increase the crosslinking density. A low molecular weight polyol having a molecular weight of 62 to 200 is preferable because the hardness can be adjusted by increasing the hardness. Also,
In order to adjust the number of functional groups in the molecule, it is more preferable to use the above polyether polyol in combination with a trivalent low molecular weight polyol.

Preferred specific examples of the polyether polyol include polytetramethylene ether glycol, polypropylene glycol, polyethylene glycol and the like, and preferred specific examples of the low molecular weight polyol include trimethylolpropane, glycerin and the like. .

Examples of the organic polyisocyanate used for producing the polyurethane acrylate include aliphatic diisocyanates, alicyclic diisocyanates, araliphatic diisocyanates, aromatic diisocyanates, trivalent or higher polyisocyanates (hereinafter simply referred to as polyisocyanates). ) And the like.

Examples of the aliphatic diisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate,
2,3-diisocyanate, butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4-
Alternatively, 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methylcaproate and the like can be mentioned.

Examples of the alicyclic diisocyanate include 1,3-cyclopentane diisocyanate and 1,4
-Cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-
3,5,5-Trimethylcyclohexyl isocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis ( Isocyanate methyl) cyclohexane and the like can be mentioned.

Examples of the araliphatic diisocyanate include 1,3- or 1,4-xylene diisocyanate or a mixture thereof, ω, ω'-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-. Examples thereof include bis (1-isocyanate-1-methylethyl) benzene or a mixture thereof.

Examples of the aromatic diisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4 '.
-Diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate and the like can be mentioned.

Examples of the polyisocyanate include triphenylmethane-4,4 ', 4''-triisocyanate, 1,3,5-triisocyanatebenzene,
2,4,6-triisocyanate Organic triisocyanates such as toluene; Polyisocyanate monomers such as organic tetraisocyanates such as 4,4′-diphenyldimethylmethane-2,2′-5,5′-tetraisocyanate;
Dimers, trimers, biurets, and allophanates derived from the polyisocyanate monomer; 2,4,6-obtained from carbon dioxide and the polyisocyanate
Polyisocyanate having oxadiazinetrione ring; the above polyisocyanate monomer and ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1,6-
Hexane glycol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin,
Adducts of trimethylolpropane, pentaerythritol, sorbitol and other low molecular weight polyols having a molecular weight of less than 200; the polyisocyanate monomer and the above-mentioned polyether polyols, polyester polyols, polyether ester polyols and polyesters having a molecular weight of 200 to 5000. Examples thereof include amide polyols, polycarbonate polyols, polyhydroxyalkanes, castor oil, adducts with polyurethane polyols, and the like.

These organic polyisocyanates can be used alone or in combination of two or more.

Of these, aliphatic diisocyanates, alicyclic diisocyanates, and aromatic alicyclic diisocyanates are preferable. Among the aliphatic diisocyanates, alicyclic diisocyanates, and aromatic alicyclic diisocyanates, specific examples of preferable compounds include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3- or 1, 4-bis (isocyanatomethyl) cyclohexane, 1,3-bis (1
-Isocyanate-1-methylethyl) benzene, hexamethylene diisocyanate and the like are preferable. When the isocyanate is used, the uncured product of the obtained potting composition is easy to use because the viscosity does not become so high.
The cured product has excellent weather resistance.

As the hydroxyl group-containing acrylate used in the production of the above-mentioned polyurethane acrylate, any conventionally known one can be used. Specific examples of the hydroxyl group-containing acrylate include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 4-hydroxycyclohexyl acrylate,
Examples thereof include caprolactone-modified hydroxyethyl acrylate.

The above-mentioned hydroxyl group-containing acrylate can be used alone or in combination of two or more kinds.

In producing the polyurethane acrylate, first, the polyol and the organic polyisocyanate are mixed at an (NCO / OH) equivalent ratio of 1.3 to 3.5,
Preferably, the reaction is carried out at 1.6 to 2.8 to produce an isocyanate having a urethane bond in one molecule and an NCO group at the terminal, and then reacted with a hydroxyl group-containing acrylate.

The above reaction can be carried out by using a known catalyst such as dibutyltin laurate, stannas octoate, dibutyltin acetate, etc. under the conditions of the usual urethanization reaction. At this time, if necessary, a solvent such as ethyl acetate, butyl acetate, acetone, toluene, methyl isobutyl ketone may be used.

The polyurethane acrylate obtained by the above reaction has an average number of functional groups (f) in the molecule of 2.0.
<F ≦ 2.5 and number average molecular weight of 1000 to 50
00, the concentration of urethane groups is 1.4 to 3.6 mmol /
g is preferable. The number of functional groups in the molecule refers to the number of unreacted NCO groups and OH groups per molecule.

When the number average molecular weight of the polyurethane acrylate is less than 1000, the ultraviolet curability is good, but the hardness (JIS-A) may be too high in some cases, and the bending property of the product is deteriorated. On the other hand, when the number average molecular weight exceeds 5,000, the hardness (JIS-A) tends to be too soft with a hardness of less than about 50, and residual tack occurs, and the viscosity of the potting composition before curing increases. It tends to be too high. Further, when the average number of functional groups (f) is 2 or less, the ultraviolet curability is lowered and properties such as water resistance tend to be deteriorated, while when the average number of functional groups (f) exceeds 2.5, ultraviolet curing is performed. Although the property is good, it becomes hard and the bending property tends to deteriorate. Further, the urethane group concentration is 1.4 mmol / g
If it is less than 5,000, it becomes soft as in the case where the molecular weight exceeds 5,000 and residual tackiness is likely to occur. On the other hand, if the urethane group concentration exceeds 3.6 mmol / g, the molecular weight becomes 1
Similar to the case of less than 000, the ultraviolet curability and the like are good, but the tendency is to become too hard.

Next, the reactive diluent (B) having a polymerizable double bond used as a raw material of the ultraviolet-curable soft potting composition according to the present invention will be described.

One of the purposes of use of these reactive diluents having a double bond is to adjust the viscosity of the uncured potting composition, but the reactivity and weather resistance of the cured product of the potting composition. , Those which do not adversely affect the chemical resistance and other properties are preferable.

As the reactive diluent having a polymerizable double bond, a conventionally known one can be used,
Examples of these compounds include compounds having a structure in which (meth) acrylic acid is bonded to a compound containing an amino group, a hydroxyl group, an alkoxy group and the like by an esterification reaction and an amidation reaction. These compounds are divided into monofunctional, bifunctional, and polyfunctional compounds.

Specific examples of the monofunctional polymerizable diluent include, for example, methoxyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, nonylphenoxyethyl (meth) acrylate, 3-chloro-2-hydroxypropyl. (Meth) acrylate, phenoxyethyl (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, methoxy polyethylene (meth) acrylate, butoxy polyethylene glycol (meth) acrylate, alkyl (meth) acrylate, cyclohexyl (meth)
Acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxyethyl (meth)
Acrylate, 2-hydroxypropyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentadiene (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth ) Acryloyloxyethyl-2-hydroxyethylphthalic acid, 3-acryloyloxyglycerin mono (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-1- (meth) acryloxy-3-
(Meth) acryloxypropane, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, polyε-caprolactone mono (meth) acrylate, dialkylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, mono [2 -(Meth) acryloyloxyethyl] acid phosphate, trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, 2,2,3,4,4,4-hexafluorobutyl (Meth) acrylate, perfluorooctylethyl (meth) acrylate, dicyclopentenyloxyalkyl (meth) acrylate, dicyclopentenyl (meth) acrylate, tricyclodecanyl (meth) acrylate, trisic Decanyl oxyethyl (meth)
Examples thereof include acrylate, isobornyloxyethyl (meth) acrylate, morpholine (meth) acrylate, N-vinylpyrrolidone, N-vinylpyridine and N-vinylcaprolactone. In addition to the above compounds, as a monofunctional polymerizable diluent,

[0051]

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Mainly composed of neopentyl glycol acrylic acid benzoate represented by (Kyoeisha Chemical Co., Ltd.
Light acrylate BA-104 manufactured by Co., Ltd.,

[0053]

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Ethoxydiethylene glycol acrylic acid multimeric ester represented by (Osaka Organic Chemical Industry Co., Ltd. Viscoat # 190D),

[0055]

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Tetrahydrofurfuryl alcohol acrylic acid multimeric ester represented by (Osaka Organic Chemical Industry)
(Viscoat # 150D manufactured by Co., Ltd.),

[0057]

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C _{2 to} C _{4 of} C _{6 to} C ₁₄ (having 6 to ₁₄ carbon atoms, the same applies hereinafter) represented by
Acrylic ester of alkylene oxide adduct of Aronix TO-1 manufactured by Toagosei Chemical Industry Co., Ltd.
210),

[0059]

Embedded image

2-hydroxy-acrylic acid represented by
3-phenyloxypropyl (Toagosei Chemical Industry Co., Ltd.)
Manufactured by Aronix M-5710) and the like.

Specific examples of the bifunctional polymerizable diluent include, for example, di (meth) acrylate of 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate and ethylene glycol. Di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth)
Acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,6-hexanediol acrylic acid Multimeric ester, glycerin di (meth) acrylate, neopentyl glycol di (meth) acrylate, neopentyl glycol acrylic acid multimeric ester, hydroxypivalic acid neopentyl glycol di (meth) acrylate,
Di (meth) acrylate of 2,2 '-(hydroxyethoxyphenyl) propane, di (meth) acrylate of tricyclodecane dimethylol, addition of (meth) acrylic acid to 2,2'-di (glycyloxyphenyl) propane Things etc. are mentioned.

Specific examples of the trifunctional or higher polyfunctional polymerizable diluent include, for example, trimethylolpropane tri (meth) acrylate, trimethylolpropane trioxyethyl acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra ( (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tris (acryloxy) isocyanate, tri (meth) acrylate of tris (hydroxyethyl) isocyanurate, tris Tri (meth) acrylate of (hydroxypropyl) isocyanurate, triallyl trimellitic acid, triallyl isocyanurate and the like can be mentioned.

The reactive diluent having a polymerizable double bond may be used alone or in combination of two or more kinds.

Next, the (C) photopolymerization initiator used as a raw material of the ultraviolet-curable soft potting composition according to the present invention will be described.

As the photopolymerization initiator, those conventionally known can be used. As the photopolymerization initiator,
For example, 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid ester, 2,2-dimethoxy-2-phenylacetophenone, acetophenone diethyl ketal,
Alkoxy acetophenone, benzophenone, 3,3-
Benzophenone derivatives such as dimethyl-4-methoxybenzophenone, 4,4-dimethoxybenzophenone and 4,4-diaminobenzophenone; alkyl benzoylbenzoate, bis (4-dialkylaminophenyl) ketone,
Benzyl derivatives such as benzyl and benzylmethyl ketal; benzoin derivatives such as benzoin and benzoin isobutyl ether; benzoin isopropyl ether, 2
-Hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, methylbenzoyl formate, xanthone, thioxanthone, thioxanthone derivative, fluorene, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,2
6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2-methyl-1- [4-
(Methylthio) phenyl] -2-morpholinopropane-
1,2-benzyl-2-dimethylamino-1- (morpholinophenyl) -butanone-1 and the like can be mentioned.

Among these, from the standpoint that the cured potting composition has excellent curability (the curing speed is high), 1-
Hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and methylbenzoylformate are preferred. The photopolymerization initiator may be used alone or in combination of two or more kinds.

In the ultraviolet-curable soft potting composition comprising the above-mentioned (A) polyurethane acrylate, (B) reactive diluent and (C) photopolymerization initiator, the polyurethane acrylate and the reactive diluent are usually used. The ratio of polyurethane acrylate is preferably 25 to 60% by weight, and the reactive diluent is preferably 40 to 75%.

The ratio of the polyurethane acrylate is 2
If it is less than 5% by weight, various physical properties such as flexibility and chemical resistance tend to deteriorate, while if the proportion of the polyurethane acrylate exceeds 60% by weight, the viscosity tends to be high and handling tends to be difficult. Occurs.

The content of the photopolymerization initiator is preferably 0.5 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the ultraviolet curable component consisting of polyurethane acrylate and a reactive diluent. Parts are more preferred.

If the content of the photopolymerization initiator is less than 0.5 parts by weight per 100 parts by weight of the ultraviolet-curable component, the curing tends to be insufficient, while the content of the photopolymerization initiator is When the amount exceeds 10 parts by weight per 100 parts by weight of the ultraviolet curable component, the excess photoinitiator acts as a plasticizer, and the cured product becomes soft and brittle, or the photoinitiator bleeds out on the surface of the cured product over time. A tendency arises.

If necessary, in order to accelerate the photopolymerization reaction by the above-mentioned photopolymerization initiator, for example, tertiary amines such as triethylamine and triethanolamine; alkylphosphine-based photopolymerization promotion such as triphenylphosphine Agents, thioether-based photopolymerization accelerators such as p-thiodiglycol, and the like may be added. The addition amount of these compounds is usually 0. 0 per 100 parts by weight of the ultraviolet curable component.
A range of 5 to 10 parts by weight is preferred.

Further, in the ultraviolet-curable soft potting composition according to the present invention, in addition to the components described above, for example, a polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, t-butyl hydroxytoluene,
3,5-di-t-butyl-4-hydroxytoluene, pentaerythrityl-tetrakis-3- (3,5-di-t
-Butyl-4-hydroxyphenyl) propionate,
Antioxidants such as octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, tris (tridecyl) phosphite, tetraphenyldipropylene glycol diphosphite, triphenylphosphite, 2- (5-Methyl-2-hydroxyphenyl) benzotriazole, 2- (3-t-butyl-5-
UV absorbers such as methyl-2-hydroxyphenyl) -5-chlorobenzotriazole and 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2,6,2 ', 6'- Hydrolysis inhibitors such as tetraisopropyldiphenylcarbodiimide, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, butylbenzyl phthalate, diisodecyl phthalate, dibutyl sebacate, tricresyl phosphate, diphenylcresol phosphate, phosphorus Plasticizers such as triphenyl acid, slip agents such as methylphenyl silicone, polyoxyethylene alkyl, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkylphenyl ether sulfate ester salt, alkyldipheny Ether disulfonates, additives such as a surfactant such as polyoxyethylene alkyl ether sulfate or the like can be used as needed.

To produce the ultraviolet-curable soft potting composition, first, the above-mentioned (A) polyurethane acrylate, (B) reactive diluent and (C) photopolymerization initiator are mixed in the above-mentioned proportions, Mix thoroughly. From the viewpoint of workability, the viscosity of the compound before curing is usually 300 to 5000 mPa.s at 25 ° C. s is preferable and 500 to 2000 mPa.s. The range of s is more preferable.

As a method for potting the composition having the above-mentioned viscosity, for example, a method of potting through a metering valve with a pump can be mentioned. Specifically, a dispenser is preferable.

Further, the potting target is, as described above, household appliances, light electric appliances, miscellaneous goods, emblems of automobile interior and exterior parts, marks, stickers, touch switches and the like.

The thickness of the coating film at the time of potting is not particularly limited, but is usually preferably 0.5 to 10 mm, more preferably 0.5 to 5 mm.

When the thickness of the coating film is less than 0.5 mm, the coating film is too thin, so that scratches are likely to occur. On the other hand, when the thickness of the coating film exceeds 10 mm, the curability tends to decrease. Occurs.

In order to cure the above composition, after potting the composition on an emblem or the like, it is immediately pre-cured by a near-ultraviolet lamp, a low-ultraviolet fluorescent lamp, a low-pressure mercury lamp or the like, and then a high-pressure mercury lamp or a metal halide lamp Finally cure.

In this way, the pre-curing and final curing
Curing shrinkage can be prevented by curing at the stage. Therefore, even if potting is applied to a soft resin emblem or the like, warping does not occur.

The near-ultraviolet lamp has a main wavelength of 35.
It is possible to use one having an output of 2 nm and an output of 0.2-6 W. Examples of the near-ultraviolet lamp include chemical lamps (complement device fluorescent lamps) 4 to 40 W. Also,
At the time of pre-curing, it is possible to use a high pressure mercury lamp, a metahalide lamp, or the like. In this case, a low light amount (5
It is also possible to prevent curing shrinkage by slowly curing under (about 50 mJ / cm ² ) (that is, irradiation for a short time).

[0081]

EXAMPLES AND COMPARATIVE EXAMPLES Examples of the ultraviolet-curable soft potting composition according to the present invention will be described below, but the present invention is not limited to the following examples. The parts in the examples are parts by weight.

Example 1 Polytetramethylene ether glycol (number average molecular weight 2000) 100 was placed in a reaction vessel.
40 g of 0-5 and 1,3-bis (1-isocyanate-1-methylethyl) benzene 256.6 g were charged.
After heating to 0 ° C., 0.03 g of dibutyltin dilaurate was added, and the mixture was allowed to react for 3 hours while maintaining the temperature at 70 to 80 ° C. Next, after cooling the reaction solution to about 70 ° C., 4.5 g of trimethylolpropane was added,
The reaction was again performed at a temperature of 70 to 80 ° C. for 3 hours. To the reaction mixture having a urethane group thus obtained, 0.41 g of tert-butyl hydroxytoluene and 0.25 g of dibutyltin laurate were added, and 118.3 g of 2-hydroxyethyl acrylate was added dropwise over about 30 minutes to react. Then, the temperature of the reaction solution is increased to 55-
2250 showing an isocyanate group while maintaining at 65 ° C
The reaction was carried out until the infrared absorption spectrum at cm ^-1 disappeared (about 5 hours) to obtain a polyurethane acrylate having a number average molecular weight of 2800.

100 parts of this polyurethane acrylate,
90 parts of tetrahydrofurfuryl acrylate and 5.7 parts of 1-hydroxycyclohexyl phenyl ketone were mixed to prepare a UV-curable soft potting composition A (uncured product).

Example 2 Polytetramethylene ether glycol (number average molecular weight 650) 113.
8 g, polytetramethylene ether glycol (number average molecular weight 2000) 590 g, and 1,3-bis (1-isocyanate-1-methylethyl) benzene 265.2.
g, and after heating to 40 to 50 ° C., 0.03 g of dibutyltin dilaurate was added, and this mixed solution was added to 70 to 80
The reaction was carried out for 3 hours while maintaining the temperature of ° C. Next, this reaction liquid was cooled to 70 ° C., 10.3 g of trimethylolpropane was added, and the reaction was carried out again at a temperature of 70 to 80 ° C. for 3 hours. The reaction mixture having a urethane group thus obtained was cooled to about 40 ° C., 0.33 g of tert-butylhydroxytoluene and 0.21 g of dibutyltin laurate were added, and further 118.3 g of 2-hydroxyethyl acrylate was added. The reaction is carried out by dropping over 30 minutes, and then the reaction liquid temperature is 55 to 65 ° C.
2250 cm ^-1 showing an isocyanate group while maintaining
The reaction was carried out until the infrared absorption spectrum of (2) disappeared (about 5 hours) to obtain a polyurethane acrylate having a number average molecular weight of 2,300.

100 parts of this polyurethane acrylate,
90 parts of tetrahydrofurfuryl acrylate and 5.7 parts of 1-hydroxycyclohexyl phenyl ketone were mixed to prepare a UV-curable soft potting composition B (uncured product).

[Example 3] Polytetramethylene ether glycol (number average molecular weight 650) 217.
8 g, polytetramethylene ether glycol (number average molecular weight 2000) 220 g, and 1,3-bis (1-isocyanate-1-methylethyl) benzene 284.7.
g, and after raising the temperature to 40 to 50 ° C., 0.02 g of dibutyltin dilaurate was added, and this mixed solution was added to 70 to 80
The reaction was carried out for 30 minutes while maintaining the temperature of ° C. Next, after cooling the reaction liquid to 70 ° C., 19.7 g of trimethylolpropane was added, and the reaction was again performed at a temperature of 70 to 80 ° C. for 3 hours. The reaction mixture having a urethane group thus obtained was cooled to about 40 ° C., 0.26 g of tert-butylhydroxytoluene and 0.15 g of dibutyltin laurate were added, and 118.3 g of 2-hydroxyethyl acrylate was added to about 30%. The reaction is performed by dropwise addition over a period of time, and subsequently, while maintaining the reaction liquid temperature at 55 to 65 ° C., the reaction is performed until the infrared absorption spectrum at 2250 cm ⁻¹ indicating an isocyanate group disappears (about 5 hours), and the number average molecular weight 1900 polyurethane acrylates were obtained.

100 parts of this polyurethane acrylate,
85 parts of tetrahydrofurfuryl acrylate and 5.7 parts of 1-hydroxycyclohexyl phenyl ketone were mixed to prepare a UV-curable soft potting composition C (uncured product).

[Example 4] 28.5 parts of the polyurethane acrylate obtained in Example 3 and light acrylate B
A-104 11.5 parts, Viscoat # 190D 8.
5 parts, Aronix TO-1210 43.0 parts, Aronix M-5710 8.5 parts, and 1-hydroxycyclohexyl phenyl ketone 2.0 parts were mixed to prepare a UV-curable soft potting composition D (uncured product). did.

Example 5 Polytetramethylene ether glycol (number average molecular weight 650) 195 was placed in a reaction vessel.
g and 1,3-bis (1-isocyanate-1-methylethyl) benzene 207.7 g were charged, and 40 to 50
After the temperature was raised to 0 ° C, 0.02 g of dibutyltin dilaurate was added, and while maintaining this mixture at a temperature of 70 to 80 ° C, 3
The reaction was performed for 0 minutes. Next, the reaction solution was cooled to 70 ° C., 17.9 g of trimethylolpropane was added, and the reaction solution was added to 7
The reaction was carried out at a temperature of 0 to 80 ° C for 3 hours. The reaction mixture having a urethane group thus obtained was cooled to about 40 ° C., and then tertiary butyl hydroxytoluene 0.1 was added.
5 g and 0.08 g of dibutyltin laurate were added, and further 2-hydroxyethyl acrylate 82.8.
g for about 30 minutes to carry out the reaction, and then, while maintaining the reaction solution temperature at 55 to 65 ° C., carry out the reaction until the infrared absorption spectrum at 2250 cm ⁻¹ indicating an isocyanate group disappears (about 5 hours). , Number average molecular weight 16
00 polyurethane acrylate was obtained.

100 parts of this polyurethane acrylate,
90 parts of tetrahydrofurfuryl acrylate and 5.7 parts of 1-hydroxycyclohexyl phenyl ketone were mixed to prepare a UV-curable soft potting composition E (uncured product).

Example 6 Polytetramethylene ether glycol (number average molecular weight 650) 195 was placed in a reaction vessel.
g and 1,3-bis (1-isocyanate-1-methylethyl) benzene 317.7 g were charged, and 40 to 50
After the temperature was raised to 0 ° C, 0.04 g of dibutyltin dilaurate was added, and while maintaining this mixed solution at a temperature of 70 to 80 ° C, 3
The reaction was performed for 0 minutes. Next, after cooling the reaction solution to 70 ° C., 17.9 g of trimethylolpropane was added,
The reaction was again performed at a temperature of 70 to 80 ° C. for 3 hours. The reaction mixture having urethane groups thus obtained was cooled to about 40 ° C., 0.21 g of tertiary butyl hydroxytoluene and 0.12 g of dibutyl tin laurate were added, and further 2-hydroxyethyl acrylate 18 was added.
9.3 g was added dropwise over about 30 minutes to carry out the reaction, and subsequently, while maintaining the reaction solution temperature at 55 to 65 ° C., the reaction was continued until the infrared absorption spectrum at 2250 cm ⁻¹ indicating an isocyanate group disappeared (about 5 hours). Then, a polyurethane acrylate having a number average molecular weight of 1030 was obtained.

100 parts of this polyurethane acrylate,
70 parts of tetrahydrofurfuryl acrylate and 5.7 parts of 1-hydroxycyclohexyl phenyl ketone were mixed to prepare a UV-curable soft potting composition F (uncured product).

[Example 7] Polytetramethylene ether glycol (number average molecular weight 650) 217.
8 g, polytetramethylene ether glycol (number average molecular weight 2000) 220 g, 2,4-tolylene diisocyanate (Coronate T manufactured by Nippon Polyurethane Industry Co., Ltd.)
-100) 202.9 g, and benzoyl chloride 0.04
g, and after heating to 40 to 50 ° C., 0.01 g of dibutyltin dilaurate was added, and this mixed solution was added to 60 to 75
The reaction was carried out for 30 minutes while maintaining the temperature of ° C. Next, after cooling the reaction solution to 70 ° C., 19.7 g of trimethylolpropane was added, and the reaction was carried out at a temperature of 70 to 80 ° C. for 3 hours. The reaction mixture having a urethane group thus obtained was cooled to about 40 ° C., 0.23 g of tert-butylhydroxytoluene and 0.15 g of dibutyltin laurate were added, and further 118.3 g of 2-hydroxyethyl acrylate was added. The reaction was carried out by dropping over 30 minutes, and subsequently, while maintaining the reaction solution temperature at 55 to 65 ° C., the reaction was carried out until the infrared absorption spectrum at 2250 cm ⁻¹ indicating an isocyanate group disappeared (about 5 hours), and the number average A polyurethane acrylate having a molecular weight of 1750 was obtained.

100 parts of this polyurethane acrylate,
85 parts of tetrahydrofurfuryl acrylate, 2.8 parts of 1-hydroxycyclohexyl phenyl ketone, and 2.8 parts of methylbenzoyl formate were mixed to prepare a UV-curable soft potting composition G (uncured product).

[Example 8] 100 parts of the polyurethane acrylate of Example 3, 85 parts of tetrahydrofurfuryl acrylate, 2.8 parts of 1-hydroxycyclohexyl phenyl ketone and 2.8 parts of methylbenzoyl formate were mixed to obtain an ultraviolet curing type. A soft potting composition H (uncured product) was prepared.

[Example 9] Polytetramethylene ether glycol (number average molecular weight 650) 217.
8 g, polytetramethylene ether glycol (number average molecular weight 2000) 220 g, and 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate 258.9 g were charged, and the temperature was raised to 40 to 50 ° C.,
0.02 g of dibutyltin dilaurate was added, and the mixture was reacted for 30 minutes while maintaining the temperature at 70 to 80 ° C. Next, after the reaction solution was cooled to 70 ° C., 19.7 g of trimethylolpropane was added, and 70 to 8 again.
The reaction was performed at a temperature of 0 ° C. for 3 hours. After cooling the reaction mixture having urethane groups thus obtained to about 40 ° C.,
Tert-butyl hydroxytoluene 0.25 g,
And 0.15 g of dibutyltin laurate were added, and 118.3 g of 2-hydroxyethyl acrylate was further added dropwise over about 30 minutes to carry out the reaction. Subsequently, while maintaining the reaction solution temperature at 55 to 65 ° C., the isocyanate group was removed. The reaction was carried out until the infrared absorption spectrum at 2250 cm ^-1 indicated disappeared (about 5 hours) to obtain a polyurethane acrylate having a number average molecular weight of 1850.

100 parts of this polyurethane acrylate,
85 parts of tetrahydrofurfuryl acrylate, 2.8 parts of 1-hydroxycyclohexyl phenyl ketone, and 2.8 parts of methylbenzoyl formate were mixed to prepare a UV-curable soft potting composition I (uncured product).

Example 10 Polytetramethylene ether glycol (number average molecular weight 650) 21 was placed in a reaction vessel.
7.8 g, polytetramethylene ether glycol (number average molecular weight 2000) 220 g, and 4,4′-methylenebis (cyclohexyl isocyanate) 305.7 g
Was charged, and after heating to 40 to 50 ° C., 0.02 g of dibutyltin dilaurate was added, and this mixed solution was heated to 70 to 80 ° C.
The reaction was carried out for 30 minutes while maintaining the temperature. Next, after cooling the reaction liquid to 70 ° C., 19.7 g of trimethylolpropane was added, and the reaction was again performed at a temperature of 70 to 80 ° C. for 3 hours. The reaction mixture having a urethane group thus obtained was cooled to about 40 ° C., 0.26 g of tert-butylhydroxytoluene and 0.16 g of dibutyltin laurate were added, and further 118.3 g of 2-hydroxyethyl acrylate was added. The reaction is carried out by dropping over 30 minutes, and then the reaction liquid temperature is 55 to 65 ° C.
2250 cm ^-1 showing an isocyanate group while maintaining
The reaction was carried out until the infrared absorption spectrum of (1) disappeared (about 5 hours) to obtain a polyurethane acrylate having a number average molecular weight of 1950.

100 parts of this polyurethane acrylate,
85 parts of tetrahydrofurfuryl acrylate, 2.8 parts of 1-hydroxycyclohexyl phenyl ketone and 2.8 parts of methylbenzoyl formate were mixed to prepare a UV-curable soft potting composition J (uncured product).

[Comparative Example 1] Polytetramethylene ether glycol (number average molecular weight 2000) 120 was placed in a reaction vessel.
0 g and 24,4 g of 1,3-bis (1-isocyanate-1-methylethyl) benzene were charged, and 40 to 5
After heating to 0 ° C., 0.03 g of dibutyltin dilaurate was added, and the mixture was allowed to react for 3 hours while maintaining the temperature at 70 to 80 ° C. The reaction mixture having a urethane group thus obtained was cooled to about 40 ° C., 0.4 g of tert-butylhydroxytoluene and 0.26 g of dibutyltin laurate were added, and 81.2 g of 2-hydroxyethyl acrylate was further added. The reaction was carried out by dropping over 30 minutes, and then the reaction solution temperature was adjusted to 55-65.
The reaction was carried out for about 5 hours while maintaining the temperature at ℃. Next, 4.69 g of ethyl alcohol was added to the reaction liquid, and then the reaction liquid was kept at 55 to 65 ° C until the infrared absorption spectrum at 2250 cm ^-1 showing an isocyanate group disappeared (about 2 hours). A polyurethane acrylate having a number average molecular weight of 4050 was obtained.

100 parts of this polyurethane acrylate,
90 parts of tetrahydrofurfuryl acrylate and 5.7 parts of 1-hydroxycyclohexyl phenyl ketone were mixed to prepare a UV-curable soft potting composition K (uncured product).

Comparative Example 2 Polytetramethylene ether glycol (number average molecular weight 650) 195 was placed in a reaction vessel.
g and 1,3-bis (1-isocyanate-1-methylethyl) benzene 488.8 g were charged, and 40 to 50
After the temperature was raised to 0 ° C, 0.02 g of dibutyltin dilaurate was added, and while maintaining this mixture at a temperature of 70 to 80 ° C, 3
The reaction was performed for 0 minutes. Next, after cooling the reaction solution to about 70 ° C., 44.7 g of trimethylolpropane was added, and the reaction was again performed at a temperature of 70 to 80 ° C. for 3 hours. The reaction mixture having a urethane group thus obtained was cooled to 40 ° C., 0.3 g of tertiary butyl hydroxytoluene and 0.2 g of dibutyl tin laurate were added, and further 2-hydroxyethyl acrylate 284 was added.
g for about 30 minutes to carry out the reaction, and then, while maintaining the reaction solution temperature at 55 to 65 ° C., carry out the reaction until the infrared absorption spectrum at 2250 cm ⁻¹ indicating an isocyanate group disappears (about 5 hours). , Number average molecular weight 10
50 polyurethane acrylates were obtained.

100 parts of this polyurethane acrylate,
80 parts of tetrahydrofurfuryl acrylate and 5.4 parts of 1-hydroxycyclohexyl phenyl ketone were mixed to prepare a UV-curable soft potting composition L (uncured product).

<Evaluation Method> The viscosity of the uncured UV-curable soft potting compositions prepared in the above Examples and Comparative Examples was evaluated by the method described below, and then cured by the following method to obtain the curability. Further, the characteristics of the ultraviolet-curable soft potting composition after curing were evaluated by the methods described below.

(1) Viscosity: Measured at 25 ° C. with a B-type rotational viscometer manufactured by Shibaura System Co., Ltd.

(2) Curability: Compositions A to F prepared according to the above examples were potted on a glass plate to a thickness of 2 mm, and the ultraviolet intensity was 190 mW using a high pressure mercury lamp with an output of 80 W / cm. / Cm ² UV irradiation energy amount (mJ / c) until the surface and inside are fully cured
m ² ) was used as the measured value.

(3) Transparency: Using the test pieces whose curability was measured, the appearance was visually evaluated, and those judged to be transparent were judged to be slightly opaque, and those judged to be opaque. Was designated as x.

(4) Bendability: PET with a thickness of 50 μm
An uncured UV-curable soft potting composition according to each of Examples and Comparative Examples was potted on a pressure-sensitive adhesive sheet obtained by coating a film (polyethylene terephthalate) with white weather-resistant ink so that the thickness was 2 mm, and the potted P
After irradiating the ET film with a near-ultraviolet lamp (hereinafter referred to as a chemical lamp) 20W for 2 minutes, a high-pressure mercury lamp with an output of 80W / cm is used to irradiate the surface and the inside with a UV intensity of 190mW / cm ² until the surface and inside are sufficiently cured. (UV irradiation energy amount 860 mJ / cm ² ) to obtain a PET film on which a cured UV-curable soft potting composition was formed. Next, use these PET films for external folding 1
The bending property was evaluated by bending the product at 80 ° and 1
A sample that did not crack even when bent at 80 ° was marked with ◯, and a sample that bent when bent at 180 ° was marked with x.

(5) Hardness: Two cured products having a thickness of 7 mm produced by the following method were stacked, and the hardness was measured according to JIS K6301.

Method for producing cured product: The composition was weighed in a polyethylene container so as to have a thickness of 7 mm and irradiated with a chemical lamp of 20 W for 2 minutes, and then a high pressure mercury lamp with an output of 80 W / cm was used to obtain an ultraviolet intensity of 190 mW. / cm ² irradiation for about 6 seconds UV on its surface (ultraviolet radiation energy: 1290mJ / cm ^2), and the cured product thus obtained was taken out from the polyethylene vessel, further irradiated for about 4 seconds UV from the back surface of the cured product (Ultraviolet irradiation energy amount: 8
60 mJ / cm ² ) for hardness measurement.

(6) Heat resistance: After potting on a glass plate with a thickness of 2 mm, a coating film cured under the same conditions as in the evaluation of bendability in (4) was held at 80 ° C. for 72 hours. The film was allowed to stand for 1 hour to observe the appearance, adhesion and dimensional changes of the coating film, and those with no change were rated as "no abnormality", and those with a change were rated as x.

(7) Water resistance: A coating film prepared under the same conditions as in the evaluation of heat resistance in (6) was immersed in tap water at 25 ° C. for 240 hours and then left to stand for 1 hour to give an appearance of the coating film. Those that were observed and judged to have no change were classified as "no abnormality", and those in which a change was recognized were marked as x.

(8) Moisture and heat resistance: A coating film prepared under the same conditions as the evaluation of heat resistance in (6) was left under the conditions of 60 ° C. and 97% relative humidity for 168 hours, and then left to stand for 1 hour. The appearance of the coating film was observed, and when there was no change, it was judged as "no abnormality", and when there was a change, it was marked as x.

(9) Hot water resistance: The coating film prepared under the same conditions as the heat resistance evaluation in (6) was immersed in warm water at 40 ° C. for 24 hours, and then allowed to stand for 1 hour to observe the appearance of the coating film. When there was no change, it was judged as "no abnormality", and when there was a change, it was marked as x.

(10) Detergent resistance: A coating film prepared under the same conditions as the heat resistance evaluation in (6) was treated with a household detergent (Mama Lemon) at room temperature for 2 times.
Drop it, let it stand for 24 hours, rinse off the detergent with water, wipe off the water, observe the appearance of the coating film, and judge that there is no change, "no abnormality", and if there is a change, mark x. did.

(11) Cooling / heating cycle: A coating film prepared under the same conditions as the bending property of (4) (80 ° C. × 4 hours → 25 ° C. × 1 hour → -20 ° C. × 4 hours → 25 ° C. × 1 hour) The cooling and heating cycle according to the temperature condition of 10) was repeated 10 times, the appearance of the coating film was then observed, and the adhesion was measured. Was designated as x.

(12) Weather resistance: A coating film prepared under the same conditions as the heat resistance evaluation in (6) was put in a sunshine weather meter weather tester (black panel 62 ± 3 ° C., with rain), and 2
The color difference after the lapse of 00 hours was measured by the transmission method and is shown as ΔE.

<Evaluation Results> The UV-curable soft potting compositions (A to J) prepared in Examples 1 to 10 and the potting compositions (K to L) prepared in Comparative Examples 1 and 2 were used. The number average molecular weight of urethane acrylate, the number of functional groups, the concentration of urethane groups, and the measurement results of the above-mentioned properties are shown in Tables 1 and 2 below.

[0119]

[Table 1]

[0120]

[Table 2]

The UV-curable soft potting compositions A to F according to the examples shown in Table 1 above had a functional group number of 2.0.
Although the hardness was changed to 6 to 2.31, the hardness can be changed to 53 to 78 according to the change in the number of functional groups, and the various properties shown in Table 1 are good. That is, the ultraviolet-curable soft potting composition according to the example has a soft cured product (JIS-A: 50-
80) is excellent in touch feeling, its softness can be easily adjusted, its curing speed is fast, it is transparent and flexible, and it has heat resistance, water resistance, wet heat resistance, warm water resistance, detergent resistance,
Excellent in various characteristics such as cooling / heating cycle.

On the other hand, the potting composition K according to the comparative example shown in Table 2 above has a small number of functional groups of 1.86, so that it is inferior in curability and has poor water resistance.
Further, since the potting composition L according to the comparative example had a too large number of functional groups of 2.53, the hardness of the cured product was too large and the bending property was poor, and the coating film changed even in the cooling / heating cycle.

Further, the UV-curable soft potting compositions G to J according to the examples shown in Table 2 above were prepared under the same conditions as in Example 3, except that the diisocyanate component was changed. An ultraviolet-curable soft potting composition was prepared by mixing 100 parts of the obtained polyurethane acrylate, 85 parts of tetrahydrofurfuryl acrylate, 2.8 parts of 1-hydroxycyclohexyl phenyl ketone, and 2.8 parts of methylbenzoyl formate. In this case, the weather resistance is also measured.

Also in this case, the ultraviolet-curable soft potting compositions G to H according to the examples had soft cured products (JIS-A: 50 to 80) and excellent feel, and the softness thereof was easily adjusted. Can be cured quickly, transparent and flexible, heat resistance, water resistance, moist heat resistance,
Excellent in various properties such as hot water resistance, detergent resistance, thermal cycle and weather resistance. However, since the ultraviolet-curable soft potting composition G uses 2,4-tolylene diisocyanate, the weather resistance is slightly lowered.

[0125]

In the ultraviolet-curable soft potting composition (1) according to the present invention, the average number of functional groups (f) in the molecule (A) is in the range of 2.0 <f ≦ 2.5. Since it is made by reacting a polyurethane acrylate, (B) a reactive diluent having a polymerizable double bond, and (C) a photopolymerization initiator, it is soft and has excellent feel, and its softness can be easily adjusted. A UV-curable soft potting composition that can be cured, has a fast curing rate, is transparent, has flexibility, and has excellent properties such as heat resistance, water resistance, moist heat resistance, warm water resistance, detergent resistance, heat cycle, and weather resistance. Can be provided.

Further, the ultraviolet-curable soft potting composition (2) according to the present invention has the same hardness (J
Since IS-A) is 50 to 80, in addition to the effect described in (1) above, the softness of the cured product is appropriately adjusted, and an ultraviolet-curable soft potting composition having particularly excellent feel and the like is provided. You can

The ultraviolet-curable soft potting composition (3) according to the present invention has a urethane group concentration of 1.4 in the ultraviolet-curable soft potting composition described in (1) or (2) above. Since it is ~ 3.6 mmol / g, in addition to the effect described in (1) above, the viscosity of the potting composition before curing becomes an appropriate value, and a thick film can be easily formed during potting. The cured potting composition also has a hardness (JIS-A) of 50 to 8
Can hold 0.

Further, in the ultraviolet-curable soft potting composition (4) according to the present invention, the above (1) to (3) are used.
In the ultraviolet curable soft potting composition described,
Since the polyurethane acrylate has an ether group in the molecule and uses a polyether polyol having a molecular weight of 200 to 4000 and a low molecular weight polyol having a molecular weight of 62 to 200 as raw materials, the effect described in (1) above. In addition, by adjusting the amounts of the two types of polyols, the characteristics such as hardness can be easily adjusted.

Further, the ultraviolet-curable soft potting composition (5) according to the present invention has the above-mentioned (1) to (4).
In the ultraviolet curable soft potting composition described,
0.5 to 10 parts by weight of a photopolymerization initiator is added to 100 parts by weight of an ultraviolet curable component consisting of 25 to 60% by weight of a polyurethane acrylate and 40 to 75% of a reactive diluent having a polymerizable double bond. Therefore, in addition to the effect described in (1) above, it is possible to provide the potting composition which has a faster curing rate and is excellent in various properties.

Further, in the method for producing an ultraviolet-curable soft potting composition according to the present invention, the average number of functional groups (f) in the molecule (A) is in the range of 2.0 <N ≦ 2.5. 2 containing a polyurethane acrylate, (B) a reactive diluent having a polymerizable double bond, and (C) a photopolymerization initiator
Viscosity at 5 ° C. is 300 to 5000 mPa.s. The uncured potting composition of s is pre-cured with a near-ultraviolet lamp, a low-ultraviolet fluorescent lamp, a low-pressure mercury lamp or the like, and then finally cured with a high-pressure mercury lamp or a metal halide lamp, so that there is little curing shrinkage and it is soft (JIS-A: 50-
80) and excellent in touch feeling, fast curing speed, transparent and flexible, and UV curing excellent in various properties such as heat resistance, water resistance, moist heat resistance, warm water resistance, detergent resistance, thermal cycle and weather resistance. Mold soft potting compositions can be produced.

Claims (6)

[Claims] 1. A polyurethane acrylate having (A) an average number of functional groups (f) in the molecule in the range of 2.0 <f ≦ 2.5, (B) a reactive diluent having a polymerizable double bond, and ( C) A UV-curable soft potting composition obtained by reacting a photopolymerization initiator. 2. The ultraviolet-curable soft potting composition according to claim 1, which has a hardness (JIS-A) of 50-80. 3. The ultraviolet-curable soft potting composition according to claim 1, wherein the concentration of urethane groups in the polyurethane acrylate is 1.4 to 3.6 mmol / g. 4. The polyurethane acrylate is produced from a polyether polyol having an ether group in the molecule and having a molecular weight of 200 to 4000 and a low molecular weight polyol having a molecular weight of 62 to 200 as raw materials.
The ultraviolet-curable soft potting composition according to any one of 3 above. 5. Polyurethane acrylate 25 to 60% by weight, and reactive diluent 40 to 7 having a polymerizable double bond.
Per 100 parts by weight of the UV curable component consisting of 5%,
The ultraviolet-curable soft potting composition according to claim 1, which comprises 0.5 to 10 parts by weight of a photopolymerization initiator. 6. A polyurethane acrylate having (A) an average number of functional groups (f) in the molecule in the range of 2.0 <f ≦ 2.5, (B) a reactive diluent having a polymerizable double bond, and ( C) The viscosity at 25 ° C containing the photopolymerization initiator is 3
00-5000 mPa.s. An ultraviolet-curable soft potting composition, characterized in that the uncured potting composition of s is pre-cured with a near-ultraviolet lamp, low-ultraviolet fluorescent lamp, low-pressure mercury lamp or the like, and then finally cured with a high-pressure mercury lamp or a metal halide lamp. Production method.