PHOTOCURABLE COMPOSITION, PHOTOCURABLE FOAM COMPOSITION, URETHANE (METH)ACRYLATE COMPOUND, AND METHOD FOR PRODUCING FOAM

Abstract

Provided are: a photocurable composition capable of forming a sealant composed of a foam endowed with excellent elongation and excellent tensile strength by being cured while foamed; a photocurable foam composition in which gas bubbles are included in the aforementioned photocurable composition; a urethane (meth)acrylate compound that is suitably used as a component of the aforementioned photocurable composition; and a method for producing a foam using the abovementioned photocurable composition. In this photocurable composition, which contains a urethane (meth)acrylate (A) and a photopolymerization initiator (C), a urethane (meth)acrylate compound having a specific structure that includes a urethane bond, has a polyether chain having a molecular weight within a specific range in the center, and has (meh) acryloyloxy groups at both ends of a linear polyether chain is used as the urethane (meth)acrylate (A).

Claims

1. A photocurable composition comprising: a urethane (meth)acrylate (A); and a photopolymerization initiator (C), wherein the urethane (meth)acrylate (A) comprises a urethane (meth)acrylate compound represented by a formula (A1) below:
(CH.sub.2?CR.sup.5COOR.sup.4OCONH).sub.aR.sup.2NHCO(OR.sup.1).sub.nOCONHR.sup.3(NHCOOR.sup.4OCOCR.sup.5?CH.sub.2).sub.b(A1) wherein, in the formula (A1), R.sup.1 is an alkylene group having 2 or more and 4 or less carbon atoms, R.sup.2 is a group in which isocyanate groups are removed from an a+1-valent aliphatic isocyanate compound, R.sup.3 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, R.sup.4 is an alkylene group having 1 or more and 8 or less carbon atoms, R.sup.5 is a hydrogen atom or a methyl group, a molecular weight of a unit represented by (OR.sup.1).sub.nO in the formula (A1) is 3000 or more and 30000 or less and n is a repetition number of oxyalkylene groups represented by OR.sup.1.

2. The photocurable composition according to claim 1, wherein a and b are each 1.

3. The photocurable composition according to claim 1, wherein a ratio of a mass of the urethane (meth)acrylate compound represented by the formula (A1) to a mass of the urethane (meth)acrylate (A) is equal to or greater than 60% by mass.

4. The photocurable composition according to claim 3, wherein R.sup.1 is a propane-1,2-diyl group.

5. The photocurable composition according to claim 1 further comprising: a photopolymerizable monomer (B), wherein 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 (B3).

6. The photocurable composition according to claim 1, wherein 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)acrylate (B2-1), a chain aliphatic mono(meth)acrylate (B3-1) and an alicyclic mono(meth)acrylate (B3-2).

7. The photocurable composition according to claim 1, wherein the photopolymerization initiator (C) comprises at least one selected from the group consisting of an alkylphenone photopolymerization initiator, an acylphosphine oxide photopolymerization initiator and an oxime ester photopolymerization initiator.

8. The photocurable composition according to claim 1, wherein the photocurable composition is used for manufacturing a foam through mixing with a gas and photocuring.

9. A photocurable foam composition comprising: the photocurable composition according to claim 1; and bubbles (E) of a gas dispersed in the photocurable composition.

10. The photocurable foam composition according to claim 9, wherein the gas is one or more selected from a group consisting of nitrogen, argon, xenon, krypton and carbon dioxide.

11. The photocurable foam composition according to claim 9, wherein a 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 ?m and equal to or less than 200 ?m.

12. A urethane (meth)acrylate compound represented by a formula (A1) below:
(CH.sub.2?CR.sup.5COOR.sup.4OCONH).sub.a-R.sup.2NHCO(OR.sup.1).sub.nOCONHR.sup.3(NHCOOR.sup.4OCOCR.sup.5?CH.sub.2).sub.b(A1) wherein, in the formula (A1), R.sup.1 is an alkylene group having 2 or more and 4 or less carbon atoms, R.sup.2 is a group in which isocyanate groups are removed from an a+1-valent aliphatic isocyanate compound, R.sup.3 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, R.sup.4 is an alkylene group having 1 or more and 8 or less carbon atoms, R.sup.3 is a hydrogen atom or a methyl group, a molecular weight of a unit represented by (OR.sup.1).sub.nO in the formula (A1) is 3000 or more and 30000 or less and n is a repetition number of oxyalkylene groups represented by OR.sup.1.

13. A method for manufacturing a foam, the method comprising: mixing the photocurable composition according to claim 1 with a gas to generate a photocurable foam composition comprising bubbles; and exposing the photocurable foam composition to photocure the photocurable foam composition.

14. The method for manufacturing a foam according to claim 13, wherein the generating of the photocurable foam composition comprises: supplying the photocurable composition which is pressure fed in a first conduit and the gas which is pressure fed via a second conduit using a first pump, and mixing the photocurable composition and the gas to generate a mixture; dispersing the gas into the photocurable composition in a dispersion conduit in a state where the mixture is pressurized; and foaming the mixture by discharging the mixture which has passed through the dispersion conduit so as to generate the photocurable foam composition.

15. The method for manufacturing a foam according to claim 13, wherein the exposing is LED exposure.

16. The method for manufacturing a foam according to claim 13, wherein an 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 according to claim 13, wherein 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 of (I) to (III) are achieved with a manipulator simultaneously or continuously.

18. The method for manufacturing a foam according to claim 13, wherein 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 according to claim 13, wherein 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 discharging the gas other than oxygen from the photocurable foam composition when the photocurable foam composition is generated.

Description

EXAMPLES

[0110] Although the present invention will be further specifically described below using Examples, the scope of the present invention is not limited to these Examples.

Examples 1 to 7, Comparative Example 1, and Comparative Example 2

[0111] In Examples 1 to 7, Comparative Example 1 and Comparative Example 2, the following PO1 to PO6 were used as glycols or triols. [0112] PO1: polypropylene glycol (molecular weight of 2000, number of hydroxyl groups of 2) [0113] PO2: polyropylene glycol (molecular weight of 3000, number or hydroxyl groups of 2) [0114] PO3: polypropylene triol (molecular weight of 5100, number of hydroxyl groups of 3, branched triol obtained by adding propylene oxide to glycerin) [0115] PO4: polypropylene glycol (molecular weight of 10000, number of hydroxyl groups of 2) [0116] PO5: polypropylene glycol (molecular weight of 15000, number of hydroxyl groups of 2) [0117] PO6: polypropylene glycol (molecular weight of 8000, number of hydroxyl groups of: 2)

[0118] 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) [0119] I2: isophorone diisocyanate

[0120] In Examples 1 to 7, Comparative Example 1 and Comparative Example 2, 2-hydroxyethyl acrylate (HEA) was used as hydroxyalkyl (meth)acrylate.

[0121] In Examples 1 to 7, Comparative Example 1 and Comparative Example 2, the following CA1 or CA2 was used as a catalyst. [0122] CA1: tin octoate [0123] CA2: dibutyl tin laurate

[0124] 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.

[0125] 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.

TABLE-US-00001 TABLE 1 Comparative Example Example 1 2 3 4 5 6 7 1 2 Glycol or triol PO1 58.80 74.70 (Parts by mass) PO2 66.02 54.39 33.85 4.99 PO3 2.31 4.20 PO4 32.63 56.43 89.87 95.66 PO5 93.61 PO6 92.21 Polyisocyanate I1 21.17 29.90 (Parts by mass) I2 8.51 6.36 3.37 2.84 4.19 5.12 16.60 HEA 5.54 4.45 3.34 1.77 1.49 2.19 2.66 7.10 8.70 (Parts by mass) Catalyst CA1 0.01 (Parts by mass) CA2 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Viscosity (mPa .Math. s) 40000 60000 85000 90000 143000 100000 95000 40000 35000 Molecular weight of 10000 10000 10000 10000 15000 10000 8000 2000 2000 polyoxyalkylene unit

Examples 8 to 23, and Comparative Examples 3 to 5

[0126] 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).

[0127] In Examples 8 to 23 and Comparative Examples 3 to 5, the following M1 to M5 were used as photopolymerizable monomers (B) [0128] M1: isobornyl acrylate [0129] M2: trimethylolpropane triacrylate [0130] M3: pol tetramethylene glycol diacrylate [0131] M4: 1,9-nonanediol diacrylate [0132] M5: lauryl acrylate

[0133] In Examples 8 to 23 and Comparative Examples 3 to 5, the following PI1 to PI3 were used. [0134] PI1: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (made by IGM Resins B.V., Omnirad TPO-H) [0135] PI2: 1-hydroxycyclohexyl phenyl ketone (made by IGM Resins B.V., Omnirad 184) [0136] PI3: 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(O-benzoyloxime) (made by BASF Japan, OXE01)

[0137] 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.

[0138] 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 (N.sub.2 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.

<Measurement of Asker C Hardness>

[0139] 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/cm.sup.2, 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).

<Measurements of M50, M1.00 and Tb>

[0140] 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/cm.sup.2 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 N.sub.2 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.

<Heat Resistance Evaluation>

[0141] 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. [0142] Very good: no change in appearance [0143] Good: no change in appearance but stickiness was observed on surface [0144] Satisfactory: ends of cured product melted [0145] Poor: cured product melted

<Deep Curability Evaluation>

[0146] 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'.sup.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.

<Surface Tack Evaluation>

[0147] 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/cm.sup.2 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 N.sub.2 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 N.sub.2 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. [0148] Very good: no sticky feeling when touched [0149] Good: sticky feeling was produced but no fingerprint was adhered [0150] Satisfactory: fingerprint was adhered on surface [0151] Poor: liquid was adhered

TABLE-US-00002 TABLE 2 Example 8 9 10 11 12 13 14 Urethane Type Ex. 5 Ex. 5 Ex. 5 Ex. 5 Ex. 5 Ex. 5 Ex 5 (meth) Parts 97.6 88.0 88.0 88.0 88.0 88.0 91.0 acrylate by (A) mass Photo- Type M2 M2 M2 M2 M2 M2 polymerizable Parts 9.6 9.6 9.6 9.6 9.6 9.6 monomer (B) by mass Photo- Type PI1/PI2 PI1/PI2 PI2 PI2 PI1 PI3 PI3 polymerization Parts 0.5/0.5 0.5/0.5 1.0 0.5 0.5/0.5 0.5 1 initiator (C) by mass Viscosity (mPa .Math. s) 130000 60000 60000 60000 60000 60000 50000 Asker C hardness 15 20 20 20 20 20 20 Elongation (%) 120 100 100 100 100 100 100 M50 (kPa) 350 400 400 400 400 400 400 M100 (kPa) 800 950 950 950 950 950 950 Tb (kPa) 950 950 950 950 950 950 950 Heat resistance Poor Very Very Very Very Very Very (140? C. for good good good good good good 24 hours) Deep curability 12 mm 12 mm >23 mm >23 mm 12 mm 17 mm 6 mm Surface tack Satis- Satis- Poor Satis- Satis- Satis- Good (Without N.sub.2 factory factory factory factory factory spraying) Surface tack Very Good Good Good Very Very Very (With N.sub.2 spraying) good good good good

TABLE-US-00003 TABLE 3 Example 15 16 17 18 19 20 21 Urethane Type Ex. 5 Ex. 5 Ex. 5 Ex. 1 Ex. 2 Ex. 2 Ex. 3 (meth) Parts 91.0 91.0 91.0 88.0 88.0 88.0 88.0 acrylate by (A) mass Photo- Type M3 M4 M5 M1 M2 M2 M2 polymerizable Parts 6.6 6.6 6.6 9.6 9.6 9.6 9.6 monomer (B) by mass Photo- Type PI1/PI2 PI1/PI2 PI1/PI2 PI1/PI2 PI1/PI2 PI2 PI2 polymerization Parts 1 1 1 1 1 1 1 initiator (C) by mass Viscosity (mPa .Math. s) 50000 50000 50000 80000 40000 45000 50000 Asker C hardness 15 15 14 14 28 26 25 Elongation (%) 120 120 120 120 90 100 100 M50 (kPa) 350 400 350 4050 650 550 450 M100 (kPa) 900 950 950 950 1000 950 Tb (kPa) 1000 1050 1050 1050 1150 1000 950 Heat resistance Good Good Satis- Very Very Very Very (140? C. for factory good good good good 24 hours) Deep curability >23 mm >23 mm >23 mm >23 mm >23 mm >23 mm >23 mm Surface tack Satis- Satis- Satis- Satis- Satis- Satis- Satis- (Without N.sub.2 factory factory factory factory factory factory factory spraying) Surface tack Very Very Good Very Very Very Very (With N.sub.2 spraying) good good good good good good

TABLE-US-00004 TABLE 4 Examples Comparative Examples 22 23 24 3 4 5 Urethane Type Ex. 4 Ex. 6 Ex. 7 Comp. Comp. Comp. (meth) Ex. 1 Ex. 2 Ex. 2 acrylate Parts 88.0 88.0 88.0 91.0 91.0 97.6 (A) by mass Photo- Type M2 M2 M2 M2 M2 polymer- Parts 9.6 9.6 9.6 6.6 6.6 izable by monomer mass (B) Photo- Type PI2 PI2 PI2 PI2 PI2 PI2 polymer- Parts 1 1 1 1 1 1 ization by initiator mass (C) Viscosity 55000 60000 55000 30000 30000 40000 (mPa .Math. s) Asker C 22 22 25 32 35 30 hardness Elongation (%) 120 100 100 60 60 80 M50 (kPa) 350 450 500 850 800 700 M100 (kPa) 800 950 950 900 Tb (kPa) 1000 950 950 900 800 900 Heat resistance Very Very Very Very Very Poor (140? C. for good good good good good 24 hours) Deep >23 >23 >23 >23 >23 >23 curability mm mm mm mm mm mm Surface tack Satis- Satis- Satis- Satis- Satis- Satis- (Without N.sub.2 factory factory factory factory factory factory spraying) Surface tack Very Very Very Very Very Very (With N.sub.2 good good good good good good spraying)

[0152] 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.