Patent Application
20240166794
The present invention relates to a photocurable composition, a photocurable foam composition including bubbles of a gas in the photocurable composition, a urethane (meth)acrylate compound suitably used as a component of the photocurable composition and a method for manufacturing a foam using the photocurable composition.
When in the manufacturing of parts of various electrical and mechanical products and automobile parts, for example, a plurality of parts are assembled or parts having gaps are used, the mating surfaces or gaps of the parts are often sealed. As such a sealing method, a method is known in which a liquid material for forming a gasket called a FIPG (Formed In Place Gasket) is applied to the mating surfaces or the gaps while being foamed by gas, and is cured. According to this method, a sealant formed by foaming and curing the FIPG is used o seal the mating surfaces and the gaps of the parts.
As a curable composition which can be used as the FIPG, a photocurable sealing material is known which includes, in a specific ratio, (A) an oligomer including a (meth)acryloyl group having a weight average molecular weight, of 10,000 to 30,000, (B) a (meth)acrylate monomer and (C) a polythiol compound (see Patent Document)
However, when the conventionally known curable composition as disclosed in Patent Document 1 is applied to the manufacturing of a foam to manufacture the foam, it is difficult to form a sealant of a foam which has both satisfactory elongation and satisfactory tensile strength.
The present invention is made in view of the problem described above, and an object of the present invention is to provide a photocurable composition which can form a sealant of a foam having both satisfactory elongation and satisfactory tensile strength by being cured while being foamed, a photocurable foam composition including bubbles of a gas in the photocurable composition, a urethane (meth)acrylate compound suitably used as a component of the photocurable composition and a method for manufacturing a foam using the photocurable composition.
The present inventors have found that by using a photocurable composition including a urethane (meth)acrylate (A) an a photopolymerization initiator (C), in which as the urethane (meth)acrylate (A), a urethane (meth)acrylate compound having a specific structure is used, which includes a urethane bond, a polyether chain having a molecular weight in a specific range in the center, and (meth)acryloyloxy groups at both ends of a linear polyether chain, it is possible to solve the problem described above, with the result that the present inventors have completed the present invention. Specifically, the present invention provides (1) to (22) below.
(1) A photocurable composition including: a urethane (meth)acrylate (A); and a photopolymerization initiator (C), the urethane (meth)acrylate (A) including a urethane (meth)acrylate compound represented by a formula (A1) below:
(CH2═CR5—CO—O—R4—O—CO—NH)a-R2—NH—CO—(O—R1)n—O—CO-NH-R3—(NH—CO—O—R4—O—CO—CR5═CH2)b (A1)
in which, in the formula (A1), R1 is an alkylene group having 2 or more and 4 or less carbon atoms, R2 is a group in which isocyanate groups are removed from an a+1-valent aliphatic isocyanate compound, R3 is a group in which isocyanate groups are removed from a b+1-valent aliphatic isocyanate compound, a and b are each independently 1 or 2, R4 is an alkylene group having 1 or more and 8 or less carbon atoms, R5 is a hydrogen atom or a methyl group, a molecular weight of a unit represented by —(O-R1)n—O— in the formula (A1) is 3000 or more and 30000 or less and n is a repetition number of oxyalkylene groups represented by —O—R1—.
(2) The photocurable composition as described in aspect (1), in which a and b are each 1.
(3) The photocurable composition as described in aspect (1) or (2), in which the ratio of the mass of the urethane (meth)acrylate compound represented by the formula (A1) to the mass of the urethane (meth)acrylate (A) is equal to or greater than 60% by mass.
(4) The photocurable composition as described in aspect (3), in which R1 is a propane-1,2-diyl group.
(5) The photocurable composition as described in any one of aspects (1) to (4) further including: a photopolymerizable monomer (B), in which the photopolymerizable monomer (B) is one or more selected from the group consisting of a tri(meth)acrylate (B1), a di(meth)acrylate (B2) and a mono(meth)acrylate (3).
(6) The photocurable composition as described in any one of aspects (1) to (5), in which the photopolymerizable monomer (B) is at least one selected from the group consisting of a chain aliphatic tri(meth)acrylate (B1-1), a chain aliphatic di(meth)acry ilate (B2-1), a chain aliphatic mono(meth)acrylate (B3-1) and an alicyclic mono(meth)acrylate (B3-2).
(7) The photocurable composition as described in any one of aspects (1) to (6), in which the photopolymerization initiator (C) includes at least one selected f-rom the group consisting of an alkylphenone photopolymerization initiator, an acylphosphine oxide photopolymerization initiator and an oxime ester photopolymerization initiator.
(8) The photocurable composition as described in any one of aspects (1) to (10), in which the photocurable composition is used for manufacturing a foam through mixing with a gas and photocuring.
(9) A photocurable foam composition including: the photocurable composition as described in any one of aspects (1) to (8); and bubbles (E) of a gas dispersed in the photocurable composition.
(10) The photocurable foam composition as described in aspect (9), in which the gas is one or more selected from the group consisting of nitrogen, argon, xenon, krypton and carbon dioxide.
(11) The photocurable foam composition as described in aspect (9) or (10), in which the size of each of the bubbles (E) of the gas in a cured material which has been cured under atmospheric pressure is equal to or greater than 5 μm and equal to or less than 200 μm.
(12) A urethane (meth)acrylate compound represented by a formula (A1) below:
(CH2═CR5—CO—O—R4—O—CO—NH)a-R2—NH—CO—(O—R1)n—O—CO—NH—R3—(NH—CO—O—R4—O—CO—CR5═CH2)b (A1)
in which, in the formula (A1), R1 is an alkylene group having 2 or more and 4 or less carbon atoms, R2 is a group in which isocyanate groups are removed from an a+1-valent aliphatic isocyanate compound, R3 is a group in which isocyanate groups are removed from a b+1-valent aliphatic isocyanate compound, a and b are each independently 1 or 2, R4 is an alkylene group having 1 or more and 8 or less carbon atoms, R5 is a hydrogen atom or a methyl group, a molecular weight of a unit represented by —(O—R1)n—O— in the formula (A1) is 3000 or more and 30000 or less and n is a repetition number of oxyalkylene groups represented by —O—R1—.
(13) A method for manufacturing a foam, including: mixing the photocurable composition as described in any one of aspects (1) to (8) with a gas to generate a photocurable foam composition including bubbles; and
(14) The method for manufacturing a foam as described in aspect (13), where the generating of the photocurable foam composition includes:
(15) The method for manufacturing a foam as described in aspect (13) or (14), in which the exposing is LED exposure.
(16) The method for manufacturing a foam as described in any one of aspects (13) to (15), in which the oxygen concentration on a surface of the photocurable foam composition when the photocurable foam composition is exposed is equal to or less than 3% by volume.
(17) The method for manufacturing a foam as described in any one of aspects (13) to (16), in which among (I) the generating of the photocurable foam composition, (II) setting the oxygen concentration on the surface of the photocurable foam composition to equal to or less than 1% by volume and (III) the curing of the photocurable foam composition by the exposing, (I) and (III) or all of (I) to (III) are achieved with a manipulator simultaneously or continuously.
(18) The method for manufacturing a foam as described in any one of aspects (13) to (17), in which the setting of the oxygen concentration on the surface of the photocurable foam composition to equal to or less than 3% by volume is performed by a method of spraying a gas other than oxygen to the surface of the photocurable foam composition.
(19) The method for manufacturing a foam as described in any one or aspects (13) to (18), in which the setting of the oxygen concentration on the surface of the photocurable foam composition equal to or less than 3% by volume is performed by discharging a the gas other than oxygen from the photocurable foam composition when the photocurable foam composition is generated.
According to the present invention, it is possible to provide a photocurable composition which can form a sealant of a foam having both satisfactory elongation and satisfactory tensile strength by being cured while being foamed, a photocurable foam composition including bubbles of a gas in the photocurable composition, a urethane (meth)acrylate compound suitably used as a component of the photocurable composition and a method for manufacturing a foam using the photocurable composition.
A photocurable composition includes a urethane (meth)acrylate (A) and a photopolymerization initiator (C) The urethane (meth)acrylate (A) includes a urethane (meth)acrylate compound represented by a formula (A1) below:
(CH2═CR5—CO—O—R4—O—CO—NH)a—R2—NH—CO—(O—R1)n—O—CO—NH—R3—(NH—CO—O—R4—O—CO—CR5═CH2)b (A1).
In the formula (A1), R1 is an alkyl ene group having 2 or more and 4 or less carbon atoms, R2 is a group in which isocyanate groups are removed from an a+1-valent aliphatic isocyanate compound, R3 is a group in which isocyanate groups are removed from a b+1-valent aliphatic isocyanate compound, a and b are each independently 1 or 2, R4 is an alkylene group having 1 or more and 8 or less carbon atoms, R5 is a hydrogen atom or a methyl group, a molecular weight of a unit represented by —(O—R1)n—O— in the formula (A1) is 3000 or more and 30000 or less and n is a repetition number of oxyalkylene groups represented by —O—R1—.
The photocurable composition includes the urethane (meth)acrylate compound represented by the formula (A1) above, and thus it is possible to form a sealant of a foam having both satisfactory elongation and satisfactory tensile strength by curing the photocurable composition while foaming the photocurable composition.
Hence, the photocurable composition is suitably used for manufacturing a foam through mixing with a gas and photocuring.
The viscosity of the photocurable composition which is a viscosity measured by a BH type viscometer using a No. 7 rotor at 20° C. at a rotation speed of 20 rpm is equal to or greater than 10000 mPa·s and equal to or less than 300000 mPa·s, more preferably equal to or greater than 20000 mPa·s and equal to or less than 250000 mPa·s and further preferably equal to or greater than 50000 mPa·s and equal to or less than 150000 mPa·s. When the viscosity of the photocurable composition is excessively high, it may be difficult to apply the photocurable composition at room temperature. When the viscosity of the photocurable composition is excessively low, if the photocurable composition is used to form beads, it may be difficult to hold the desired shape of the beads. A method for adjusting the viscosity of the photocurable composition is not particularly limited. The viscosity of the photocurable composition is typically adjusted by adjusting the viscosity of the urethane (meth)acrylate (A). The viscosity of the photocurable composition can be adjusted, for example, by mixing a low-viscosity monomer component with the photocurable composition or adjusting the amount of filler mixed.
The essential or optional components of the photocurable composition will be described below.
<Urethane (meth)acrylate (A)>
The photocurable composition includes the urethane (meth) acrylate (A) as a curable component. The urethane (meth)acrylate (A) includes, as an essential component, the urethane (meth)acrylate compound represented by the formula (A1) below:
(CH2═CR5—CO—O—R4—O—CO—NH)a—R2—NH—CO—(O—R1)n—O—NH—R3—(NH—CO—O—R4—O—CO—CR5═CH2)b (A1).
In the formula (A1), R1 is an alkyl ene group having 2 or more and 4 or less carbon atoms, R2 is a group in which isocyanate groups are removed from an a+1-valent aliphatic isocyanate compound, R3 is a group in which isocyanate groups are removed from a b+1-valent aliphatic isocyanate compound, a and b are each independently 1 or 2, R4 is an alkylene group having 1 or more and 8 or less carbon atoms, R5 is a hydrogen atom or a methyl group, a molecular weight of a unit represented by —(O—R1)n—O— in the formula (A1) is 3000 or more and 30000 or less and n is a repetition number of oxyalkylene groups represented by —O—R—.
The photocurable composition includes, as the urethane (meth)acrylate (A), the urethane (meth)acrylate compound represented by the formula (A1) above, and thus it is possible to form a sealant of a foam having both satisfactory elongation and satisfactory tensile strength by curing the photocurable composition while foaming the photocurable composition. As long as the object of the present invention is not interfered with, in addition to the urethane (meth)acrylate compound represented by the formula (A1) above, the photocurable composition may include a urethane (meth) acrylate compound having a structure which is not applicable to the formula (A1).
In the specification and claims of the present application, “(meth)acrylate” means both “acrylate” and “methacrylate”, “(meth)acryloyl” means both “acryloyl” and “methacryloyl” and “(meth)acrylic acid” means both “acrylic acid” and “methacrylic acid”.
In the formula (A1), R1 is an alkylene group having 2 or more and 4 or less carbon atoms. As described above, in the formula (A1), the molecular weight of a unit represented by —(O—R1)n—O— is 3000 or more and 30000 or less. Hence, the urethane (meth)acrylate compound represented by the formula (A1) includes a plurality of oxyalkylene groups represented by —O—R1—. In other words, in the formula (A1), a plurality of R1 s are present. A plurality of R1 s in the formula (A1) may be only one type of alkylene group or two or more types of alkylene groups.
The unit represented by —(O—R1)n—O— is typically introduced into the urethane (meth)acrylate compound represented by the formula (A1) using a polyoxyalkylene glycol represented by H—(O—R1)n—OH. Hence, the molecular weight of the polyoxyalkylene glycol is selected as necessary, and thus the molecular weight of the urethane (meth)acrylate compound represented by the formula (A1) can be adjusted.
In order to set the viscosity of the photocurable composition to a viscosity In the preferred range described above, the viscosity of the urethane (meth)acrylate (A) which is a viscosity measured by the BH type viscometer using the No. 7 rotor at 20° C. at a rotation speed of 20 rpm is preferably equal to or greater than 30000 mPa·s and equal to or less than 300000 mPa·s, and more preferably equal to or greater than 35000 mPa·s and equal to or less than 200000 mPa·s. As a method for adjusting the viscosity of the urethane (meth)acrylate (A), a method for adjusting, as necessary, the molecular weight of a urethane (meth)acrylate compound contained in a urethane (meth)acrylate compound such as the urethane (meth)acrylate compound represented by the formula (A1) is mentioned.
Specific examples of R1 in the formula (A1) include an ethane-1,2-diyl group (ethylene group), a propane-1,3-diyl group, a propane-1,2-diyl group and a butane-1,4-diyl group. Among them, since synthesis urethane (meth)acrylate compound represented by the formula (A1) is easy and it is easy to obtain the photocurable composition which provides a cured product exhibiting desired physical properties, one or more selected from the group consisting of the ethane-1,2-diyl group (ethylene group), the propane-1,3-diyl group and the propane-1,2-diyl group is preferable, and the propane-1,2-diyl group is more preferable. When the number of carbon atoms in R1 is excessively small, the number of ether bonds included in the polyoxyalkylene structure is increased, and thus the water resistance of the cured product is impaired or the water absorption of the cured product is high, with the result that the sealing property when the cured product is used as a sealant tends to decrease. When the number of carbon atoms in R1 is excessively large, the viscosity of the photocurable composition is high, with the result that processability such as coatability tends to decrease. Therefore, the number of carbon atoms in R1 is most preferably 3.
In the formula (A1), R2 is a group in which isocyanate groups are removed from an a+1-valent aliphatic isocyanate compound. R3 is a group in which isocyanate groups are removed from a b+1-valent aliphatic isocyanate compound. a and b are each independently 1 or 2. In other words, R2 and R3 are respectively residues derived from divalent or trivalent aliphatic isocyanate compounds. The divalent or trivalent aliphatic isocyanate compounds which can provide R2 and R3 are not particularly limited as long as the object of the present invention is not interfered with. Preferred specific examples of the divalent or trivalent aliphatic isocyanate compound include: aliphatic diisocyanates such as 1,6-hexane diisocyanate (1,6-hexamethylene diisocyanate), an oligomer of 1,6-hexane diisocyanate, isophorone diisocyanate (3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate), methylene bis(4-cyclohexyl isocyanate), 2,2,4-trimethylhexamethyleone diisocyanate, 1,4-hexamethylene isocyanate, bis(2-isocyanatoethyl) fumarate and lysine diisocyanate (hexanoic acid-2,6-diisocyanate); and aliphatic triisocyanates such as 1,6,11-undecane triisocyanate, -i, diisocyanate-4-isocyanatomethyloctane, 1,3,6-hexamethylene triisocyanate and bicycloheptane triisocyanate. Trimers of the diisocyanates described above are also preferable as the trivalent aliphatic isocyanate. Examples of the trimer include isocyanurate, adduct, burette and the like.
Among these aliphatic isocyanates, since it is easy to obtain the photocurable composition which provides a cured product exhibiting desired physical properties, 1,6-hexane diisocynate (1,6-hexamethylene diisocyanate) an oligomer of 1,6-hexane diisocyanate and isophorone diisocyanate are preferable, and isophorone diisocyanate is more preferable. In particular, when isophorone diisocyanate is used, it is possible to lower the viscosity of the composition, it is possible to select a long-chain polyol and when the cured product is a foam, the cured product tends to have satisfactory elongation.
The polyoxyalkylene glycol represented by H—(O—R1)n—OH is reacted with the divalent or trivalent aliphatic isocyanate described above according to a conventional method, and thus a polyisocyanate compound represented by a formula (A1-1) below is obtained. R1, R2, R3, a, b and n in the formula (A1-1) are the same as those in the formula (A1)
(OCN)a—R2—NH—CO—(O—R1)n—O—CO—NH—R3—(NCO)b (A1-1)
The polyisocyanate compound represented by the formula (A1-1) is reacted with a hydroxyalkyl (meth)acrylate represented by a formula (A1-2) below, and thus the urethane (meth)acrylate compound represented by the formula (A1) is obtained. R4 and R5 in the formula (A1-2) are the same as those in the formula (A1).
HO—R4—O—CO—CR5═CH2 (A1-2)
R4 in the formula (A1) is an akylene group having 1 or more and 8 or less carbon atoms. The alkylene group serving as R4 may be a linear alkylene group or a branched alkylene group. The alkylene group serving as R4 is preferably a linear alkylene group. Preferred specific examples of the alkylene group serving as R4 include a methylene group, an ethane-1,2-diyl group (ethylene group), a propane-1,3-diyl group, a propane-1,2-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group and an octane-1,8-diyl group. Among these groups, the ethane-1,2-di group (ethylene group) and the propane-1,3-diyl group are preferable, and the ethane-1,2-diyl group (ethylene group) is more preferable.
The hydroxyalkyl (meth)acrylate represented by the formula (A1-2) is reacted with the divalent or trivalent aliphatic isocyanate compounds which can provide R2 and R3, an isocyanate compound represented by a formula (A1-3) below and an isocyanate compound represented by a formula (A1-4) below are adjusted and the isocyanate compound represented by the formula (A1-3) and the isocyanate compound represented by the formula (A1-4) which are obtained are reacted with the polyoxyalkylene glycol represented by H—(O—R1)n—OH, with the result that itis also possible to obtain the urethane (meth acryilate compound represented by the formula (A1). R2, R3, R4, R5, a and b in the formula (A1-3) and the formula (A1-4) are the same as those in the formula (A1).
CH2═CR5—CO—R4—O—CO—NH)a—R2—NCO (A1-3)
(CH2═CR5—CO—O—R4—O—CO—NH)b—R3—NCO (A1-4)
R5 in the formula (A1) is a hydrogen atom or a methyl group. R5 is preferably a hydrogen atom in that the cured product of the photocurable composition has satisfactory flexibility such as low hardness and high elongation.
Since it is easy to form a cured product exhibiting desired physical properties using the photocurable composition, in the formula (A1) described above, a and b are each preferably 1. In particular, a and b are each preferably 1 in that the photocurable composition of a viscosity suitable for the application is easily obtained and the cured product of the photocurable composition has satisfactory flexibility such as low hardness and high elongation.
The ratio of the mass of the urethane (meth)acrylate compound represented by the formula (A1) to the mass of the urethane (meth)acrylate (A) is not particularly limited as long as the object of the present invention is not interfered with. Since it is easy to form a cured product exhibiting desired physical properties, the ratio of the mass of the urethane (meth)acrylate compound represented by the formula (A1) to the mass of the urethane (meth)acrylate (A) is preferably equal to or greater than 60% by mass, more preferably equal to or greater than 80% by mass, further preferably equal to or greater than. 90% by mass and most preferably equal to or greater than. 100% by mass.
When the urethane (meth)acrylate (A) includes a urethane (meth)acrylate compound other than the urethane (meth)acrylate compound represented by the formula (A1), the other urethane (meth)acrylate compound is not particularly limited as long as the object of the present invention is not interfered with. As the other urethane (meth)acrylate compound, for example, a urethane (meth)acrylate compound capable of being manufactured by the reaction of polyols such as a polyester polyol and a carbonate diol, a known polyisocyanate compound and the hydroxyalkyl (meth)acrylate represented by the formula (A1-2) can be used.
The ratio of the mass of the urethane (meth)acrylate (A) to the mass of the photocurable composition is preferably equal to or greater than 50% by mass and equal to or less than 95% by mass, more preferably equal to or greater than 60% by mass and equal to or less than 94% by mass and further preferably equal to or greater than 70% by mass and equal to or less than 93% by mass. When the ratio of the mass of the urethane (meth)acrylate (A) is in the range described above, a photocurable composition is easily obtained which provides a cured product having satisfactory flexibility and elongation and has a viscosity suitable for the application.
The photocurable composition may include a photopolymerizable monomer (B) which is a compound having an ethylenically unsaturated double bond, and preferably includes the photopolymerizable monomer (B). The photopolymerizable monomer (B) is not particularly limited as long as a compound includes one or more ethylenically unsaturated double bonds and is not applicable to the urethane (meth)acrylate (A). As the photopolymerizable monomer (B), one compound may be used singly or two or more compounds may be combined to be used.
Examples of the preferred photopolymerizable monomer (B) include a (meth)acrylate compound which is not applicable to the urethane (meth)acrylate (A) and a compound, such as a (meth)acrylamide compound, which includes a (meth)acryloyl group. As the photopolymerizable monomer (B), the (meth)acrylate compound is preferable.
The number of (meth)acryloyl groups included in the photopolymerizable monomer (B) including the (meth)acryloyl group is not particularly limited. The number of (meth)acryloyl groups included in the photopolymerizable monomer (B) including the (meth)acryloyl group may be any one of 1, 2, 3 and 4 or more, and is preferably 1, 2 or 3. When the number of (meth)acryloyl groups included in the photopolymerizable monomer (B) is the number described above, a photocurable composition is easily obtained which has satisfactory photocurability and has a low viscosity suitable for the application.
For ease of availability and synthesis and ease of formation of a cured product exhibiting desired physical properties, the photopolymerizable monomer (B) is preferably one or more selected from the group consisting of a tri(meth)acrylate compound (B1), a di(meth)acrylate compound (B2) and a mono(meth)acrylate compound (B3).
Preferred specific examples of the tri(meth)acrylate compound (B3) includes trimethylolpropane tri(meth)acrylate, entaerythritol tri(meth)acrylate, tris((meth)acryloyloxyethyl) isocyanurate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated glycerol tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate and the like.
Preferred specific examples of the di(meth)acrylate compound (B2) includes: di(meth)acrylates of aliphatic glycols such as ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 2-methyl-1,3-propanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexane diol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate and 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate; di(meth)acrylates of oligo or polyalkylene glycols such as diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate and polytetramethylene glycol di(meth)acrylate; di(meth)acrylates of ethoxylated aliphatic glycols such as ethoxylated dipropylene glycol di(meth)acrylate, ethoxylated 2-methyl-1,3-propanediol di(meth) acrylate, ethoxylated 1,6-hexanediol di(meth)acrylate and propoxylated neopentyl glycol di(meth)acrylate; ethoxylated bisphenol A di(meth)acrylate; isocyurate di(meth)acrylate; and tricyclodecanedimethanol di(meth)acrylate.
Preferred specific examples of the mono(meth)acrylate compound (B3) includes: C1-C20 alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate and stearyl (meth)acrylate; alicyclic (meth)acrylates such as menthyl (meth)acrylate, norbornyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecanyl (meth)acrylate, tetracyclodecanyl (meth)acrylate and cyclic trimethylolpropane formal (meth)acrylate; 2-hydroxyethyl (meth)acrylate; ethoxylated 2-hydroxyethyl (meth)acrylate; 2-phenoxyethyl (meth)acrylate; 2-(2-ethoxyethoxy) ethyl acrylate; benzyl (meth)acrylate; and phosphoric acid (2-(meth)acryloyloxyethyl).
The photopolymerizable monomer (B) is preferably at least one selected from the group consisting of a chain aliphatic tri(meth)acrylate (B1-1), a chain aliphatic di(meth)acrylate (B2-1), a chain aliphatic mono(meth)acrylate (B3-1) and an alicyclic mono(meth)acrylate (B3-2).
When the chain aliphatic tri(meth)acrylate (B1-1) is used, the surface curability of the photocurable composition and the heat resistance of the cured product are enhanced. Examples of the chain aliphatic tri(meth)acrylate (B1-1) include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated-glycerol tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate and the like.
Examples of the chain aliphatic di(meth)acrylate (B2-1) include: di(meth)acrylates of aliphatic glycols such as ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 2-methyl-1,3-propanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexane diol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate and 2-butyl 2-ethyl-1,3-propanediol di(meth)acrylate; di(meth)acrylates of oligo or polyalkylene glycols such as diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate and polytetramethylene glycol di(meth)acrylate; di(meth)acrylates of ethoxylated aliphatic glycols such as ethoxylated dipropylene glycol di(meth)acrylate, ethoxylated 2-methyl-1,3-propanediol di(me th) acrylate, ethoxylated 1,6-hexanediol di(meth)acrylate and propoxylated neopentyl glycol di(meth)acrylate; ethoxylated bisphenol A di(meth)acrylate; isocyanurate di(meth)acrylate; and tricyclodecanedimethanol di(meth)acrylate.
Examples or the chain aliphatic mono(meth)acrylate (B3-1) include: C1-C20 alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth) acrylate, n-pentyl (meth)acrylate, n-hexyl (meth) acrylate, n-heptyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate and stearyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate; ethoxylated 2-hydroxyethyl (meth)acrylate; 2-phenoxyethyl (meth)acrylate; 2-(2-ethoxyethoxy) ethyl acrylate; and phosphoric acid (2-(meth)acryoyloxyethyl).
When the alicyclic mono(meth)acrylate (B3-2) is used, it is possible to lower the viscosity of the photocurable composition while improving the curability without lowering the flexibility (elongation) of the cured product. Examples of the alicyclic mono(meth)acrylate (B3-2) include: alicyclic (meth)acrylates such as menthyl (meth)acrylate, norbornyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecanyl (meth)acrylate, tetracyclodecanyl (meth) acrylate and cyclic trimethylolpropane formal (meth)acrylate and the like.
The ratio of the mass of the photopolymerizable monomer (B) to the mass of the photocurable composition is preferably equal to or greater than 1% by mass and equal to or less than 20% by mass, more preferably equal to or greater than 2% by mass and equal to or less than 18% by mass and further preferably equal to or greater than 5% by mass and equal to or less than 15% by mass. When the ratio of the mass of the photopolymerizable monomer (B) to the mass of the photocurable composition is in the range described above, a photocurable composition is easily obtained which has both satisfactory curability and a low viscosity, and a flexible cured product is easily formed.
The photocurable composition includes the photopolymerization initiator (C) as a component for reacting the urethane acrylate (A) with the photopolymerizable monomer (B) to cure the photocurable composition. The type of photopolymerization initiator (C) is not particularly limited as long as the object of the present invention is not interfered with. The photocurable composition may include one photopolymerization initiator (C) singly or may combine and include two or more photopolymerization initiators (C).
In order to achieve both the deep curability of the photocurable composition and the suppression of surface tack of the cured product, the photocurable composition preferably includes, as the photopolymerization initiator (C), at leas one selected from the group consisting of an alkylphenone photopolymerization initiator, an acylphosphine oxide photopolymerization initiator and an oxime ester photopolymerization initiator.
Examples of the alkylphenone photopolymerization initiator include an α-hydroxyalkylphenone compound, an α-aminoalkylphenone compound, an α-benzylketal compound and the like. The α-hydroxyalkylphenone compound is a compound having an alkylphenone skeleton in which a hydroxy group is bonded at an α-position relative to a carbonyl group. The α-aminoalkylphenone compound is a compound having an alkylphenone skeleton in which an optionally substituted amino group is bonded at an α-position relative to a carbonyl group.
Specific examples of the α-hydroxyalkylphenone compound include: 1-hydroxycyclohexyl phenyl ketone (made by IGM Resins B.V., Omnirad 184); 2-hydroxy-2-methyl-1-phenylpropanone (made by IGM Resins B.V., Omnirad 1173); 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxymethylpropanone (made by IGM Resins B.V., Omnirad 2959); 2-hydroxy-1-(4-(4-(2-hydroxypropionyl)benzyl)phenyl)-2-methylpropane-1-one (made by IGM Resins B.V., Omnirad 127); and the like. Specific examples of the α-aminoalkylphenone compound include: 2-methyl-1-[4-(methylthio)phenyl-2-morpholinopropane-1-one (made by IGM Resins B.V., Omnirad 907); 2-benzyl-2-(dimethylamino)-4′-morpholinobtyrophenone (made by IGM Resins B.V., Omnirad 369); and the like. Specific examples or the α-benzylketal compound include: 2,2-di methoxy-2-phenylacetophenone (made by IGM Resins B.V., Omnirad 651).
The acylphosphine oxide photopolymerization initiator is a pentavalent phosphorus compound which has a P═O bond and at least one acyl group bonded to the phosphorus atom of the P═O bond. As the acylphosphine oxide photopolymerization initiator, a pentavalent phosphorus compound which is conventionally used as a photopolymerization initiator and has a P═O bond and au least one acyl group bonded to the phosphorus atom of the P═O bond can be used without particular limitation.
Preferred specific examples of the acylphosphine oxide photopolymerization initiator include: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide mace by IGM Resins B.V., Omnirad TPO-H); bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (made by IGM Resins B.V., Omnirad 819); ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (made by IGM Resins B.V., Omnirad TPO-L); bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide (made by Ciba, CGI403); and the like.
In addition to the alkylphenone photopolymerizations initiator and the acylphosphine oxide photopolymerization initiator, photopolymerization initiators which can be suitably used include: benzoin photopolymerization initiators such as benzoin, benzoin methyl ether and benzoin ethyl ether; anthraquinone photopolymerization initiators such as 2-methylanthraquinone, 2-amylanthraquinone, 2-tert-butylanthraquinone and 1-chloroanthraquinone; thioxanthone photopolymerization initiators such as 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone and 2-chlorothioxanthone; benzophenone photopolymerization initiators such as benzophenone, 4-(1-tert-butyldioxy-1-methylethyl)benzophenone and 3,3′,4,4′-tetrakis(tert-butydioxycarbonyl)benzophenone; phenylglyoxylate photopolymerization initiators such as alkylphenylglyoxylate; oxime ester photopolymerization Initiators such as 1,2-octanedione, 1-[4-(phenylthio)phenyl 1,2-(O-benzoyloxime) (made by BASF Japan, OXE01), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime) (made by BASF Japan, OXE02), OXE03 (made by BASE Japan) and OXE04 (made by BASF Japan); and titanocene compound photopolymerization initiators such as bis(5,2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl) titanium.
The ratio of the mass of the photopolymerization initiator (C) to the mass of the photocurable composition is preferably equal to or greater than 0.01% by mass and equal to or less than 10% by mass, more preferably equal to or greater than 0.05% by mass and equal to or less than 5% by mass and further preferably equal to or greater than 0.1% by mass and equal to or less than 2% by mass.
The photocurable composition preferably includes a wax (D) in that the surface tack of the cured product is suppressed. Since the effect of suppressing the tack is high, as the wax (D), a wax formed of a hydrocarbon having a melting point of 60° C. or more and 75° C. or less is preferable. Examples of the wax formed of the hydrocarbon having a melting point of 60° C. or more and 75° C. or less include a paraffin wax and a microcrystalline wax.
The ratio of the mass of the wax (D) to the mass of the photocurable composition is preferably equal to or greater than 0.1% by mass and equal to or less than 8% by mass, more preferably equal to or greater than a 0.5% by mass and equal to or less than 5% by mass and further preferably equal to or greater than 1% by mass and equal to or less than 3% by mass.
As long as the object of the present invention is not interfered with, the photocurable composition may or may not include, as other components, various additives which are conventionally mixed with a photocurable composition. Examples of the other components include a polythiol compound, a carbodiimide compound, a viscosity modifier, a sensitizer, a thickener, a polymerization inhibitor, a pigment, an adhesion improver, an air oxidant, a curing accelerator, a filler, a foam stabilizer, a plasticizer, a surfactant, a lubricant, an antistatic agent and the like. The amounts of the other components used are determined as necessary with consideration given to the amounts of other components which are normally used.
As will be described later, the photocurable composition is preferably used for adjusting a photocurable foaming agent which includes bubbles of a gas. Hence, the photocurable composition preferably includes a foam stabilizer. As the foam stabilizer, a silicone foam stabilizer is preferable because it has a satisfactory foam-stabilizing effect on the photocurable composition. As the silicone foam stabilizer, a polyorganosiloxane having a siloxane structure and an ester structure or a polyorganosiloxane having a siloxane structure and an ether structure is preferable. The polyorganosiloxane which is preferable as the foam stabilizer may have two or more ester structures per molecule or may have two or more ether structures per molecule. As the ester structure, an aliphatic polyester structure is preferable. As the ether structure, a polyoxyalkylene structure is preferable. The structure of the polyorganosiloxane may have a chain structure or may have a structure including a cyclic structure. The structure of the polyorganosiloxane may be a combination of one or more chain structures and one or more cyclic structures or may be a structure in which one or more cyclic polyorganosiloxanes are linked by siloxane bonds (Si—O—Si) Regarding the molecular weight of the silicone foam stabilizer, the silicone foam stabilizer preferably includes, as a main component, polyorganosiloxane which has a number average molecular weight equal to or greater than 800 and equal to or less than 3000 and preferably equal to or greater than 1000 or equal to or less than 2000. The silicone foam stabilizer preferably includes, together with the main component describe above, high molecular weight polyorganosiloxane which has a number average molecular weight equal to or greater than 5000 and equal to or less than 20000.
The photocurable composition can be manufactured by uniformly mixing the desired amounts of components described above with a well-known mixer.
As described above, the photocurable composition described above is suitably used for mixing it with a gas and then curing it to form a foam. Hence, the photocurable composition and the photocurable foam composition including bubbles (E) of a gas dispersed in the photocurable composition are preferably used for forming a foam. A method for manufacturing the photocurable foam composition will described later as a method for manufacturing a foam.
In terms or suppressing the inhibition of curing caused by oxygen in the photocurable composition, as the gas included in the photocurable foam composition, an inert gas is preferable.
As the inert gas, one or more selected from the group consisting of nitrogen, argon, xenon, krypton and carbon dioxide are preferable.
The content of the bubbles (E) in the photocurable foam composition is not particularly limited, and is determined as necessary according to a foaming magnification for a foam obtained by curing the photocurable foam composition. The foaming magnification is, for example, preferably equal to or greater than 1.5 times and equal to or less than 5 times, and more preferably equal to or greater than 2.5 times and equal to or less than 4 times. The foaming magnification is defined by a formula below.
foaming magnification A=V1/V0
The size of each of the bubbles (E) in the photocurable composition is measured as the size of each of the bubbles (E) in the cured product of the photocurable composition which has been cured under atmospheric pressure. Typically, the photocurable composition is discharged from a nozzle under an atmospheric pressure atmosphere to form beads, thereafter a cured product obtained by exposing and curing the formed beads is used and thus the size of each of the bubbles (E) is measured. The size of each of the bubbles (E) of the gas is not particularly limited as long as the object of the present invention is not interfered with. The size of each of the bubbles (E) of the gas is, for example, preferably equal to or greater than 5 μm and equal to or less than 200 μm, and more preferably equal to or greater than 20 μm and equal to or less than 100 μm. The size of each of the bubbles of the gas can be adjusted by adjusting the strength of a shear force applied to the mixture of the photocurable composition and the gas, the amount of gas mixed with the photocurable composition, a pressure applied to the photocurable composition within the nozzle before the photocurable composition is discharged from the nozzle when the cured product is formed and the like. The magnitude of the shear force can be adjusted by adjusting the cross-sectional area of a flow path for transferring the mixture, the velocity of flow of the mixture in the flow path and the like. The size of each of the bubbles (E) of the gas ca be measured by observing, with a microscope, the cross section of the cured product of the photocurable composition which has been cured under atmospheric pressure.
A method for manufacturing a foam is not particularly limited as long as the photocurable composition described above is used. Typically, the foam can be manufactured by a method which includes: mixing the photocurable composition with a gas to generate a photocurable foam composition including bubbles; and
In the typical method for manufacturing the foam described above, the generating of the photocurable foam composition includes:
Preferably, in the first step, a piston pump which is connected to the first conduit and the second conduit is used as the first pump. First, the movement of the piston of the piston pump creates a vacuum in a space within the cylinder storing the piston. The compressed gas is filled from the second conduit into the space within the cylinder under the vacuum. Although the pressure of the gas at this time is not particularly limited, for example, the pressure is preferably equal to or greater than 0.05 MPa and equal to or less than 0.3 MPa and more preferably equal to or greater than 0.1 MPa and equal to or less than 0.2 MPa. Then, the photocurable composition is supplied by the first conduit to generate, within the cylinder, the mixture in which the photocurable composition and the gas are mixed. The pressure of the mixture generated within the cylinder is not particularly limited. For example, the pressure of the mixture generated within the cylinder is preferably equal to or greater than 5 MPa and equal to or less than. 25 MPa and more preferably equal to or greater than 15 MPa and equal to or less than 20 MPa. 0 066]
In the second step, the mixture generated in the first step as described above is pushed out into the dispersion conduit connected to the cylinder by the movement of the cylinder. At that time, a shear force is applied to the mixture within the dispersion conduit, and thus the dispersion of the bubbles of the gas into the photocurable composition progresses.
Then, in the third step, the mixture which has passed through the dispersion conduit is discharged. The mixture is generally discharged from a nozzle connected to the dispersion conduit. For example, a pressure applied to the mixture within the nozzle is preferably equal to or greater than 5 MPa and equal to or less than 20 MPa and more preferably equal to or greater than 8 MPa and equal to or less than 15 MPa. The mixture pressurized in this way is discharged under an atmospheric pressure environment, and thus the bubbles compressed in the mixture are expanded, with the result that the photocurable foam composition is generated. The pressurized mixture from the nozzle is typically discharged such that beads made of the photocurable foam composition are formed in an area to which a sealant of the foam is applied.
The photocurable foam composition formed in this way is exposed to form the cured foam. The type of light source used in the exposure is not particularly limited, and is selected as necessary with consideration given to the absorption wavelength of the photopolymerization initiator (C) and the like. As the light source used in the exposure, an LED is preferable in terms of various advantages such as a long life of the light source, energy saving, space saving, output stability and low maintenance cos.
The oxygen concentration on the surface of the photocurable foam composition when the photocurable foam composition is exposed is preferably equal to or less than 3% by volume. In this case, the inhibition of curing caused by oxygen in the surface of the photocurable foam composition is suppressed, and the tack of the foam which is formed is easily suppressed.
The oxygen concentration on the surface of the photocurable foam composition when the photocurable foam composition is exposed is measured, for example, by the following method. First, the gas in a space 1 cm to 3 cm away from the surface of the photocurable foam composition immediately before or at the start of the exposure is sampled. Then, the concentration of the sampled gas is measured using an oxygen detector tube or an oxygen concentration measuring device. For the measurement of the oxygen concentration, a detector tube 31B made by GASTEC CORPORATION, a digital oxygen concentration meter made by NEW COSMOS ELECTRIC CO., LTD., an oxygen concentration meter made by Iijima Electronics Corp. or the like can be used.
A method for setting the oxygen concentration on the surface of the photocurable foam composition to equal to or less than 3% by volume when the photocurable foam composition is exposed is not particularly limited. For example, gas other than oxygen may be sprayed to the surface of the photocurable foam composition so as to lower the oxygen concentration on the surface of the photocurable foam composition. Alternatively, when the photocurable foam composition is generated, a gas other than oxygen may be discharged from the photocurable foam composition to lower the oxygen concentration on the surface of the photocurable foam composition. As the gas other than oxygen, an inert gas such as nitrogen, argon, xenon, krypton or carbon dioxide is preferably used.
Among (I) the generating of the photocurable foam composition, (II) setting the oxygen concentration on the surface of the photocurable foam composition to equal to or less than 3% by volume and (III) the curing of the photocurable foam composition by the exposing, (I) and (III) or all (I) to (III) are preferably achieved with one or a plurality of manipulators simultaneously or continuously.
When the operations of (I) to (III) are continuously performed, for example, the interval between the operations is preferably equal to or less than 1 minute, more preferably equal to or less than 30 seconds, further preferably equal to or less than 10 seconds and particularly preferably equal to or less than 5 seconds.
For example, a single manipulator including a nozzle which discharges the mixture for generating the photocurable foam composition and a light source for exposing the photocurable foam composition is used, and thus (I) and (III) can be performed simultaneously or continuously. Even when a manipulator including a nozzle which discharges the mixture for generating the photocurable foam composition and a manipulator including a light source for exposing the photocurable foam composition are used, (I) and (III) can be performed simultaneously or continuously.
A single manipulator including: a nozzle which discharges the mixture for generating the photocurable foam composition; a gas supply device which supplies a gas other than oxygen to the surface of the photocurable foam composition; and a light source for exposing the photocurable foam composition is used, and thus (I) to (III) can be performed simultaneously or continuously.
Even when a method using a combination of a manipulator capable of performing (I) and (II) and a manipulator capable of performing (III), a method using a combination of a manipulator capable of performing (I) and (III) and a manipulator capable of performing (II), a method using a combination of a manipulator capable of performing (II) and (III) and a manipulator capable of performing (I) or a method using a combination of a manipulator capable of performing (I) a manipulator capable of performing (II) and a manipulator capable of performing (III) is used, (I) to (III) can be performed simultaneously or continuously.
When (I) and (III) are performed with a manipulator, (II) the setting of the oxygen concentration on the surface of the photocurable foam composition to equal to or less than 3% by volume may be per formed with the manipulator or may be performed with another means without use of the manipulator. For example, it is possible to enclose the vicinity of a position to which the photocurable roam composition discharged from the manipulator is exposed, to supply an inert gas to the enclosed space and to reduce the oxygen concentration.
Although the present invention will be further specifically described below using Examples, the scope of the present invention is not limited to these Examples.
In Examples 1 to 7, Comparative Example 1 and Comparative Example 2, the following PO1 to PO6 were used as glycols or triols.
In Examples 1 to 7, Comparative Example 1 and Comparative Example 2, the following I1 or I2 was used as polyisocyanate. I1: hexamethylene diisocyanate oligomer (number of isocyanate functional groups of 2, NCO content of 17.2% by mass, Duranate A201H made by Asahi Kasei Corporation)
In Examples 1 to 7, Comparative Example 1 and Comparative Example 2, 2-hydroxyethyl acrylate (HEA) was used as hydroxyalkyl (meth)acrylate.
In Examples 1 to 7, Comparative Example 1 and Comparative Example 2, the following CA1 or CA2 was used as a catalyst.
Using raw materials in the amounts shown in Table 1 urethane (meth)acrylate compounds for Examples and Comparative examples were synthesized according to the following method. Table 1 shows the viscosities of the obtained urethane (meth)acrylate compounds and the molecular weight of a polyoxyalkylene unit in the urethane (meth)acrylate compounds The viscosities were measured by a BH type viscometer using a No. 7 rotor at 20° C. at a rotation speed of 20 rpm.
Specifically, nitrogen was first caused to flow into a reaction vessel to eliminate water in the vessel. Thereafter, the dehydrated HEA was fed into the reaction vessel, and polyisocyanate was further fed thereinto. Then, the contents or the reaction vessel were stirred. Half of a catalyst was fed into the reaction vessel to start the react-ion, and the reaction was carried out by stirring the contents of the reaction vessel for 2 hours at room temperature (the reaction started at about 20° C.). After confirming that the residual amount of isocyanate group was a predetermined amount, a polyol was further added and then the contents of the reaction vessel were stirred while being heated to 80° C. When the temperature within the reaction vessel reached 80° C., the half of the catalyst was added, and the contents of the reaction vessel were stirred for 6 hours to carry out the reaction, with the result that the urethane (meth)acrylate compound was obtained.
In Examples 8 to 23 and Comparative Examples 3 to 5, the urethane (meth)acrylate compounds obtained in Examples 1 to 7, Comparative Example 1 and Comparative Example 2 were used as urethane (meth)acrylates (A).
In Examples 8 to 23 and Comparative Examples 3 to 5, the following M1 to M5 were used as photopolymerizable monomers (B)
In Examples 8 to 23 and Comparative Examples 3 to 5, the following PI1 to PI3 were used.
The types and amounts of urethane (meth)acrylates (A), photopolymerizable monomers (B) and photopolymerization initiators (C) shown in Tables 2 to 4 and 1.4 parts by mass of a foam stabilizer (0.7 parts by mass of SP-8427 and 0.7 parts by mass of SZ-1923 both of which were made by the Dow Chemical Company) were uniformly mixed using a planetary mixer, with the result that the photocurable compositions of Examples 8 to 23 and Comparative Examples 3 to 5 were obtained.
The viscosities of the photocurable compositions obtained were measured. The viscosities were measured by the BH type viscometer using the No. 7 rotor at 20° C. at a rotation speed of 20 rpm. Asker C hardness, elongation, M450 (tensile stress at 50% elongation), MIO (tensile stress at 100% elongation) and Tb (stress at break) of the cured products serving as foams were measured according to the following methods. Furthermore, the heat resistance, the deep curability and the surface tack (N2 spraying) of the photocurable compositions were evaluated according to the following methods. The results of these evaluations and measurements are shown in Tables 2 to 4.
A cylindrical polypropylene cup with a circular opening of 50 mm inside diameter (diameter), an inside depth of 12 mm and one bottom closed was filled with a photocurable foam composition using a mechanical foaming device (FOAMPLY-ST (made by Sunstar Engineering Inc.)) The photocurable foam composition was prepared by adjusting a supply gas pressure using the mechanical foaming device described above such that the foaming magnification was 4 times. The photocurable foam composition filled in the cup was then exposed for 2 seconds from a distance of 10 mm away from the surface of the photocurable foam composition using an exposure device (firejet240 (wavelength of 395 nm, made by Phoseon Technology) with an LED at an Output of 12 W/cm2, with the result that the photocured foam was formed. After the photocured foam was left at room temperature for 24 hours hardness of the foam was measured using an Asker C hardness, tester according to JIS K 6253 (ASTM D2240).
While the photocurable foam composition was being discharged from the nozzle of the mechanical foaming device onto a Teflon (registered trademark) sheet at a discharge rate of 30 cc/minute, the nozzle was moved at a robot speed of 100 mm/second, with the result that strip-shaped beads of the photocurable foam composition having a semicircular cross section with a radius of 4 mm were formed. The photocurable foam composition was prepared by adjusting the supply gas pressure using the mechanical foaming device described above such that the foaming magnification was 4 times. The strip-shaped beads were was then exposed from a distance of 15 am away from the strip-shaped beads using the exposure device firejet240 (wavelength of 395 nm, made by Phoseon Technology) with an LED at an output of 12 W/cm2 while a manipulator was being moved at a speed of 50 mm/second, with the result that the photocured strip-shaped foam was formed. While N2 gas was being sprayed toward the forward direction of movement of the nozzle at a flow rate of 20 L/second, the strip-shaped beads were was exposed. Using the resulting strip-shaped foam as a test piece, M50, M100 and Tb were measured according to JIS K 6251 (ASTM D1412) under conditions of a test speed of 200 mi/minute and a distance between chucks of 20 mm.
The cured product of the strip-shaped beads formed by the same method as in the measurements of M50, M100 and Tb was placed in an atmosphere of 140° C. for 24 hours. The appearance of the cured product of the beads after 24 hours was observed, and the heat resistance was evaluated according to the following criteria.
The curable composition was filled in a cup with a circular opening having a side surface formed of aluminum, a bottom surface formed of glass, a diameter of 15 mm and a depth of 23 mm. The curable composition filled in the cup was exposed from a height of 10 mm away from the curable composition using the exposure device (firejet240 (wavelength of 395 nm, made by Phoseon Technology) with an LED at an output of 12 W/cm'2 while a manipulator was being moved at a speed of 150 mm/second, and thereafter the cured depth from a position on the opening side of the cup was measured with a scale.
A cylindrical polypropylene cup with a circular opening of 50 mm inside diameter (diameter), an inside depth of 12 mm and one bottom closed was filled with the photocurable composition. The photocurable foam composition filled in the cup was then exposed from a height of 10 mm away from the photocurable foam composition using the exposure device (firejet240 (wavelength of 395 nm, made by Phoseon Technology) with an LED at an output of 12 W/cm2 while a manipulator was being moved at a speed of 150 mm/second, with the result that the cured product of the photocurable composition was formed. A test in which the photocurable composition in the cup was exposed while N2 gas was being sprayed at a flow rate of 20 L/second and a test in which the photocurable composition in the cup was exposed without N2 gas being sprayed were carried out. The surface tack was evaluated according to the following criteria by touching the surface of the cured product with a finger and visually observing the cured product after touching with the finger.
It is found from tables 2 to 4 that the urethane (meth)acrylate compound represented by the formula (A1) satisfying the configuration requirements described above and the photocurable composition including the photopolymerization initiator (C) are cured while being foamed, and thus it is possible to form a foam which has both satisfactory elongation and satisfactory tensile strength.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-049020 | Mar 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/013450 | 3/23/2022 | WO |
