Sheet and adhesive sheet

Abstract

A sheet is produced by curing an energy ray curable composition which includes a urethane acrylate oligomer and a compound having a thiol group in the molecule. The sheet has heat resistance to prevent outgassing.

Claims

1. A sheet produced by curing an energy ray curable composition which comprises: a urethane acrylate oligomer; a compound having a thiol group in the molecule; a photopolymerization initiator, and an energy ray polymerizable monomer, wherein said compound having a thiol group in the molecule comprises at least one selected from the group consisting of nonyl mercaptan, 1-dodecanethiol, 1,2-ethanedithiol, 1,3-propanedithiol, triazinethiol, triazinedithiol, triazinetrithiol, 1,2,3-propanetrithiol, tetraethylene glycol-bis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis thioglycolate, dipentaerythritol hexakis(3-mercaptopropionate), tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, 1,4-bis(3-mercaptobutyryloxy)butane, pentaerythritol tetrakis(3-mercaptobutyrate) and 1,3,5-tris(3-mercaptobutyloxyethyl) -1,3,5-triazine-2,4,6-(1H, 3H, 5H)-trione, wherein the sheet has a thermal weight reduction percentage of 2.1% or less when the sheet is allowed to stand in an air atmosphere at 180 C. for 60 minutes, wherein a weight average molecular weight of the urethane acrylate oligomer is 1,000 to 30,000 and wherein an amount of the energy ray polymerizable monomer is 30 to 300 parts by mass based on 100 parts by mass, in terms of solid, of the urethane acrylate oligomer.

2. The sheet according to claim 1, wherein the content of the compound having a thiol group is 2 mmol or more based on 100 g of the urethane acrylate oligomer.

3. The sheet according to claim 1, wherein the urethane acrylate oligomer comprises a structural unit derived from a polyether diol.

4. The sheet according to claim 1, wherein the sheet has a breaking elongation of 50% or more.

5. The sheet according to claim 1, wherein the sheet has a tensile elastic modulus in the range of 10 to 1000 MPa.

6. The sheet according to claim 1, wherein the sheet has a thickness of 80 to 500 m.

7. An adhesive sheet comprising: the sheet of claim 1; and an adhesive layer on at least one surface of the sheet.

8. The sheet according to claim 1, wherein the photopolymerization initiator comprises an alkylphenone photopolymerization initiator.

9. The sheet according to claim 1, wherein said compound having a thiol group in the molecule comprises tetraethylene glycol-bis(3-mercaptopropionate).

10. The sheet according to claim 1, wherein the sheet has a thermal weight reduction percentage of 1.5-2.1% when the sheet is allowed to stand in an air atmosphere at 180 C. for 60 minutes.

11. The sheet according to claim 1, wherein the energy ray polymerizable monomer comprises an aromatic(meth)acrylate selected from the group consisting of phenyl hydroxypropyl acrylate and benzyl acrylate.

12. The sheet according to claim 1, wherein the energy ray polymerizable monomer comprises a heterocyclic(meth)acrylate selected from the group consisting of tetrahydrofurfuryl(meth)acrylate, morpholine acrylate, N-vinylpyrrolidone and N-vinylcaprolactam.

13. The adhesive sheet according to claim 7, wherein the adhesive layer has a thickness of 10 to 120 m.

14. A method of producing a sheet comprising curing an energy ray curable composition comprising a urethane acrylate oligomer; a compound having a thiol group in the molecule; a photopolymerization initiator; and an energy ray polymerizable monomer, wherein said compound having a thiol group in the molecule comprises at least one selected from the group consisting of nonyl mercaptan, 1-dodecanethiol, 1,2-ethanedithiol, 1,3-propanedithiol, triazinethiol, triazinedithiol, triazinetrithiol, 1,2,3-propanetrithiol, tetraethylene glycol-bis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis thioglycolate, dipentaerythritol hexakis(3-mercaptopropionate), tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, 1,4-bis(3-mercaptobutyryloxy)butane, pentaerythritol tetrakis(3-mercaptobutyrate) and 1,3,5-tris(3-mercaptobutyloxyethyl) -1,3,5-triazine-2,4,6-(1H, 3H, 5H)-trione, wherein the sheet has a thermal weight reduction percentage of 2.1% or less when the sheet is allowed to stand in an air atmosphere at 180 C. for 60 minutes, wherein a weight average molecular weight of the urethane acrylate oligomer is 1000 to 30,000 and wherein an amount of the energy ray polymerizable monomer is 30 to 300 parts by mass based on 100 parts by mass, in terms of solid, of the urethane acrylate oligomer.

15. A method according to claim 14, wherein the sheet has a thermal weight reduction percentage of 6% or less when the sheet stands in an air atmosphere at 180 C. for 60 minutes.

Description

EXAMPLES

(1) The present invention will be described based on examples hereinbelow, but the scope of the invention is not limited to such examples. In examples and comparative examples below, the thermal weight reduction percentage, breaking elongation and tensile elastic modulus of the sheets were measured as follows.

(2) <Measurement of Thermal Weight Reduction Percentage of Sheet>

(3) A sheet was heated to 180 C. at a temperature increasing rate of 20 C./min using a thermogravimetry analyzer (DTG60 manufactured by Shimadzu Corporation), and was held at the temperature for 60 minutes. The consequent thermal weight reduction percentage was measured.

(4) <Measurement of Breaking Elongation and Tensile Elastic Modulus of Sheet>

(5) A test piece (width: 15 mm, length: 140 mm, thickness: 100 pm) was tested in accordance with JIS K7161: 1994 and JIS K7127: 1999 to determine the breaking elongation. In detail, when the test piece did not have a yield point, the tensile strain at break was measured, and the nominal tensile strain at break was measured when the test piece had a yield point. Prior to the measurement, labels for elongating the test piece were attached to edge portions that were 20 mm from each edge to prepare a dumbbell-shaped sample (width: 15 mm, length: 100 mm), and the sample was tensile tested at a stress rate of 200 mm/min with a universal tester (AUTOGRAPH AG-IS 500N manufactured by Shimadzu Corporation) to determine the tensile elastic modulus at the same time.

Example 1

(6) To an isocyanate-terminated urethane prepolymer obtained by polymerizing 33 g of polypropylene glycol having a weight average molecular weight of 4000 (hereinafter referred to as PPG 4000) and 5 g of isophorone diisocyanate (hereinafter referred to as IPDI), was reacted 10 g of pentaerythritol triacrylate (hereinafter referred to as PETA) to give a urethane acrylate oligomer having a weight average molecular weight of 17350.

(7) The urethane acrylate oligomer in an amount of 100 g (in terms of solid) was combined with 66.7 g of isobornyl acrylate as a diluting monomer, 0.83 g of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (DAROCUR 1173 manufactured by Ciba Specialty Chemicals, solid concentration: 100% by mass) as a photopolymerization initiator and 3.3 g (8.9 mmol) of tetraethylene glycol-bis(3-mercaptopropionate) (EGMP-4 manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., solid concentration: 100% by mass) as a compound having a thiol group to give an energy ray curable composition that was liquid at normal temperature (viscosity =3940 mPa.Math.s at 25 C.)

(8) The energy ray curable composition was applied on a casting carrier sheet that was a polyethylene terephthalate (PET) film (T-100 manufactured by Mitsubishi Chemical Polyester Film Corporation, thickness: 38 m) according to a fountain die technique such that the thickness would be 100 m, thereby forming a curable composition layer. UV rays were applied from the side of the curable composition layer. The UV irradiation apparatus was a belt conveyer type UV irradiation apparatus (ECS-401GX manufactured by EYE GRAPHICS Co., Ltd.), and the UV source was a high-pressure mercury lamp (H04-L4l manufactured by EYE GRAPHICS Co., Ltd. (conditions: lamp height 150 mm, lamp output 3 kW (reduced output 120 mW/cm), illumination intensity at light wavelength of 365 nm 271 mW/cm.sup.2, dose 177 mJ/cm.sup.2 (measured with UV actinometer UV-351 manufactured by ORC MANUFACTURING CO., LTD.)). Immediately after the irradiation, another identical PET film was laminated on the curable composition layer, and UV rays were applied through the newly laminated PET film two times to crosslink and cure the composition (conditions: lamp height 150 mm, lamp output 3 kW (reduced output 120 mW/cm), illumination intensity at light wavelength of 365 nm 271 mW/cm.sup.2, dose 600 mJ/cm.sup.2 (measured with UV actinometer UV-351 manufactured by ORC MANUFACTURING CO., LTD.)). Thereafter, the PET films were peeled and a UV-cured sheet having a thickness of 100 m was obtained. The sheet was tested to measure the thermal weight reduction percentage, the breaking elongation and the tensile elastic modulus. The results are set forth in Table 1.

Example 2

(9) A sheet was obtained and evaluated in the same manner as in Example 1, except that the compound having a thiol group used in Example 1 was replaced by 4.6 g (8.8 mmol) of tris [(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., solid concentration: 100% by mass) as a compound having a thiol group. The results are set forth in Table 1.

Example 3

(10) A sheet was obtained and evaluated in the same manner as in Example 1, except that the compound having a thiol group used in Example 1 was replaced by 4.3 g (8.8 mmol) of pentaerythritol tetrakis(3-mercaptopropionate) (PEMP manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., solid concentration: 100% by mass) as a compound having a thiol group. The results are set forth in Table 1.

Example 4

(11) A sheet was obtained and evaluated in the same manner as in Example 1, except that the compound having a thiol group used in Example 1 was replaced by 7.0 g (8.9 mmol) of dipentaerythritol hexakis (3-mercaptopropionate) (DPMP manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., solid concentration: 100% by mass) as a compound having a thiol group. The results are set forth in Table 1.

Example 5

(12) To an isocyanate-terminated urethane prepolymer obtained by polymerizing 33 g of polypropylene glycol having a weight average molecular weight of 1000 and 9 g of IPDI, was reacted 8 g of PETA to give a urethane acrylate oligomer having a weight average molecular weight of 20690.

(13) The urethane acrylate oligomer in an amount of 100 g (in terms of solid) was combined with 96 g of isobornyl acrylate as a diluting monomer, 1.0 g of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (DAROCUR TPO manufactured by Ciba Specialty Chemicals, solid concentration: 100% by mass) as a photopolymerization initiator and 4.0 g (10.0 mmol) of trimethylolpropane tris(3-mercaptopropionate) (TMMP manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., solid concentration: 100% by mass) as a compound having a thiol group to give an energy ray curable composition that was liquid at normal temperature (viscosity =4480 mPa.Math.s at 25 C.). A sheet was obtained and evaluated in the same manner as in Example 1, except that the above energy ray curable composition was used. The results are set forth in Table 1.

Example 6

(14) A sheet was obtained and evaluated in the same manner as in Example 1, except that the compound having a thiol group used in Example 1 was replaced by 2.2 g (10.8 mmol) of 1-dodecanethiol (manufactured by Sigma-Aldrich Co., solid concentration: 100% by mass) as a compound having a thiol group. The results are set forth in Table 1.

Example 7

(15) A sheet was obtained and evaluated in the same manner as in Example 1, except that the compound having a thiol group used in Example 1 was replaced by 4.2 g (5.4 mmol) of dipentaerythritol hexakis(3-mercaptopropionate) (DPMP manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., solid concentration: 100% by mass) as a compound having a thiol group. The results are set forth in Table 1.

Example 8

(16) A sheet was obtained and evaluated in the same manner as in Example 1, except that the compound having a thiol group used in Example 1 was replaced by 14.6 g (29.8 mmol) of pentaerythritol tetrakis(3-mercaptopropionate) (PEMP manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., solid concentration: 100% by mass) as a compound having a thiol group. The results are set forth in Table 1.

Example 9

(17) A sheet was obtained and evaluated in the same manner as in Example 1, except that the compound having a thiol group used in Example 1 was replaced by 39.2 g (80.2 mmol) of pentaerythritol tetrakis(3-mercaptopropionate) (PEMP manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., solid concentration: 100% by mass) as a compound having a thiol group. The results are set forth in Table 1.

Example 10

(18) A sheet was obtained and evaluated in the same manner as in Example 1, except that the compound having a thiol group used in Example 1 was replaced by 43.2 g (88.3 mmol) of pentaerythritol tetrakis(3-mercaptopropionate) (PEMP manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD., solid concentration: 100% by mass) as a compound having a thiol group. The results are set forth in Table 1.

Comparative Example 1

(19) A sheet was obtained and evaluated in the same manner as in Example 1, except that the compound having a thiol group was not used. The results are set forth in Table 1.

Comparative Example 2

(20) To an isocyanate-terminated urethane prepolymer obtained by polymerizing 52 g of PPG 4000 and 6 g of IPDI, was reacted 12 g of PETA to give a urethane acrylate oligomer having a weight average molecular weight of 18920.

(21) The urethane acrylate oligomer in an amount of 100 g (in terms of solid) was combined with 28.4 g of isobornyl acrylate as a diluting monomer, 14.2 g of trimethylolpropane triacrylate (TMPTA manufactured by DAICEL CHEMICAL INDUSTRIES, LTD., solid concentration: 100% by mass) and 0.71 g of 2-hydroxy-2-methyl-1-phenyl-propan-1-one (DAROCUR 1173 manufactured by Ciba Specialty Chemicals, solid concentration: 100% by mass) as a photopolymerization initiator to give an energy ray curable resin composition (viscosity =8390 mPa.Math.s at 25 C.). A sheet was obtained and evaluated in the same manner as in Example 1, except that the above energy ray curable resin composition was used. The results are set forth in Table 1.

Comparative Example 3

(22) Instead of the cured sheets from the energy ray curable compositions, a polyethylene terephthalate (PET) film (COSMOSHINE A4300 manufactured by TOYOBO CO., LTD., thickness: 188 m) was evaluated.

Comparative Example 4

(23) Instead of the cured sheets from the energy ray curable compositions, a polyethylene naphthalate (PEN) film (TEONEX Q83 manufactured by Teijin DuPont Film Japan Limited, thickness: 25m) was evaluated.

(24) TABLE-US-00001 TABLE 1 Thermal weight reduction Breaking Tensile elastic percentage (%) elongation (%) modulus (MPa) Ex. 1 3.4 91 100 Ex. 2 1.5 101 120 Ex. 3 1.8 91 117 Ex. 4 1.7 81 111 Ex. 5 1.9 95 151 Ex. 6 3.3 77 119 Ex. 7 2.1 66 161 Ex. 8 1.5 102 39 Ex. 9 1.5 150 25 Ex. 10 1.9 142 1.1 Comp. Ex. 1 33.4 80 207 Comp. Ex. 2 29.4 19 193 Comp. Ex. 3 1.3 155 4794 Comp. Ex. 4 0.7 111 6567

(25) The results in Table 1 show that the sheets in Comparative Examples 1 to 4 were inferior in one or more of the thermal weight reduction percentage, the breaking elongation and the tensile elastic modulus to the sheets in Examples 1 to 10.

(26) The sheets according to the present invention have excellent heat resistance as demonstrated above. It is therefore apparent that the adhesive sheets of the invention using the sheets similarly have excellent heat resistance.