Epoxy group-containing organopolysiloxane, ultraviolet curable silicone composition, and method of forming a cured film

Abstract

An epoxy group-containing organopolysiloxane shows the following average composition formula (1) and has an epoxy equivalent of 500 g/mol or more. The epoxy group-containing organopolysiloxane has excellent ultraviolet curability even when the content of epoxy group is small (when the epoxy equivalent is large), an ultraviolet curable silicone composition uses the same, and a method forms a cured film. ##STR00001## In the formula, each R.sup.1 represents the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms (except for a group containing an epoxy group); R.sup.2 represents a group containing an epoxy group; R.sup.3 represents a hydrogen atom or a saturated monovalent hydrocarbon group having 1 to 4 carbon atoms; a, b, and c are positive numbers, d is 0 or a positive number, satisfying (a+b)/(c+d)=0.5 to 1.0.

Claims

1. An ultraviolet curable silicone composition, comprising an onium salt photoinitiator that is configured to produce a cation species upon ultraviolet irradiation, and an epoxy group-containing organopolysiloxane that is a solid at 25 C. and that has an epoxy equivalent of 500 g/mol or more, and a weight average molecular weight of 8000 or more, wherein the epoxy group-containing organopolysiloxane is shown by the following average composition formula (1): ##STR00009## where each R.sup.1 represents the same or different unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms (except for a group containing an epoxy group); R.sup.2 represents a group containing an epoxy group; R.sup.3 represents a hydrogen atom or a saturated monovalent hydrocarbon group having 1 to 4 carbon atoms; a, b, c, and d are positive numbers, satisfying (a+b)/(c+d)=0.5 to 1.0.

2. The ultraviolet curable silicone composition according to claim 1, wherein the epoxy group-containing organopolysiloxane is an addition reaction product of (A) an organohydrogenpolysiloxane composed of an R.sup.1.sub.3SiO.sub.1/2 unit, an R.sup.1.sub.2HSiO.sub.1/2 unit, an SiO.sub.4/2 unit, and an R.sup.3OSiO.sub.3/2 unit, shown by the following average composition formula (2) and having an Si-H group content in a range of from 0.01 to 0.3 mol/100 g, ##STR00010## wherein R.sup.1, R.sup.3, a, b, c, and d have the same meanings as defined above; and (B) a compound having both of an alkenyl group and an epoxy group.

3. The ultraviolet curable silicone composition according to claim 2, wherein (A) the organohydrogenpolysiloxane has a weight average molecular weight of 6000 or more and a form of solid at 25 C.

4. A method of forming a cured film, comprising applying the ultraviolet curable silicone composition according to claim 1 onto a substrate, and performing ultraviolet irradiation to form a cured film.

5. A method of forming a cured film, comprising applying the ultraviolet curable silicone composition according to claim 2 onto a substrate, and performing ultraviolet irradiation to form a cured film.

6. A method of forming a cured film, comprising applying the ultraviolet curable silicone composition according to claim 3 onto a substrate, and performing ultraviolet irradiation to form a cured film.

7. The ultraviolet curable silicone composition according to claim 1, further comprising another epoxy group-containing organopolysiloxane in addition to the epoxy group-containing organopolysiloxane represented by formula (1).

8. The ultraviolet curable silicone composition according to claim 1, wherein the onium salt photoinitiator is selected from the group consisting of a diaryl iodonium salt, a triarylsulfonium salt, a triarylselenonium salt, a tetraarylphosphonium salt, and an aryldiazonium salt.

9. The ultraviolet curable silicone composition according to claim 8, wherein an anion in the onium salt photoinitiator is selected from the group consisting of SbF.sub.6.sup., AsF.sub.6.sup., PF.sub.6.sup., BF.sub.4.sup., HSO.sub.4.sup., and ClO.sub.4.sup..

10. The ultraviolet curable silicone composition according to claim 1, wherein an amount of the onium salt photoinitiator is in a range of from 0.1 to 20 parts by mass relative to 100 parts by mass of the ultraviolet curable silicone composition.

11. The ultraviolet curable silicone composition according to claim 1, wherein a, b, c, and d satisfy (a+b)/(c+d)=0.6 to 0.9.

12. The ultraviolet curable silicone composition according to claim 1, wherein R.sup.1 is a methyl group.

13. The ultraviolet curable silicone composition according to claim 12, wherein R.sup.3 is a hydrogen atom.

14. The ultraviolet curable silicone composition according to claim 2, wherein the SiH group content is in a range of from 0.131 to 0.3 mol/100 g.

Description

EXAMPLE

(1) Hereinafter, the present invention will be described specifically by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Example 1

(2) Into a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel, 100 parts by mass of 50% solution of organohydrogenpolysiloxane in isododecane was introduced, together with 0.1 parts by mass of 0.5 mass % solution of platinum catalyst in toluene, with the organohydrogenpolysiloxane having the average composition formula (2) in which R.sup.1 was a methyl group, R.sup.3 was a hydrogen atom, the SiH group content was 0.233 mol/100 g, and (a+b)/(c+d)=0.7, and having a weight average molecular weight of 13000. This mixture was heated to 80 C., and then 16.9 parts by mass of 1,2-epoxy-4-vinylcyclohexane was introduced into the dropping funnel and dropped to the mixture over 10 minutes. After finishing the dropping, this was stirred for 7 hours at 80 C. At this time, the progress of reaction was confirmed by .sup.1H-NMR in which the peak of hydrosilyl group (4.6 to 4.8 ppm) almost disappeared and a new peak of silethylene (0.5 to 0.7 ppm) occurred. The reaction solution was cooled to room temperature and treated with activated charcoal, followed by filtration. Then, the volatile components were removed by stripping to give 60.3 parts by mass of Silicone-A, which corresponds to the epoxy group-containing organopolysiloxane of the present invention. This was a white solid and had an epoxy equivalent of 650 g/mol and a weight average molecular weight of 18000.

Example 2

(3) Into a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel, 100 parts by mass of 50% solution of organohydrogenpolysiloxane in isododecane was introduced, together with 0.1 parts by mass of 0.5 mass % solution of platinum catalyst in toluene, with the organohydrogenpolysiloxane having the average composition formula (2) in which R.sup.1 was a methyl group, R.sup.3 was a hydrogen atom, the SiH group content was 0.131 mol/100 g, and (a+b)/(c+d)=0.7, and having a weight average molecular weight of 13000. This mixture was heated to 80 C., and then 9.8 parts by mass of 1,2-epoxy-4-vinylcyclohexane was introduced into the dropping funnel and dropped to the mixture over 10 minutes. After finishing the dropping, this was stirred for 7 hours at 80 C. At this time, the progress of reaction was confirmed by .sup.1H-NMR in which the peak of hydrosilyl group (4.6 to 4.8 ppm) almost disappeared and a new peak of silethylene (0.5 to 0.7 ppm) occurred. The reaction solution was cooled to room temperature and treated with activated charcoal, followed by filtration. Then, the volatile components were removed by stripping to give 55.2 parts by mass of Silicone-B, which corresponds to the epoxy group-containing organopolysiloxane of the present invention. This was a white solid and had an epoxy equivalent of 3300 g/mol and a weight average molecular weight of 15500.

Example 3

(4) Into a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel, 100 parts by mass of 50% solution of organohydrogenpolysiloxane in isododecane was introduced, together with 0.1 parts by mass of 0.5 mass % solution of platinum catalyst in toluene, with the organohydrogenpolysiloxane having the average composition formula (2) in which R.sup.1 was a methyl group, R.sup.3 was a hydrogen atom, the SiH group content was 0.233 mol/100 g, and (a+b)/(c+d)=0.7, and having a weight average molecular weight of 13000. This mixture was heated to 80 C., and then 2.6 parts by mass of 1,2-epoxy-4-vinylcyclohexane was introduced into the dropping funnel and dropped to the mixture over 10 minutes. After finishing the dropping, this was stirred for 7 hours at 80 C. At this time, the progress of reaction was confirmed by .sup.1H-NMR in which the peak of hydrosilyl group (4.6 to 4.8 ppm) almost disappeared and a new peak of silethylene (0.5 to 0.7 ppm) occurred. The reaction solution was cooled to room temperature and treated with activated charcoal, followed by filtration. Then, the volatile components were removed by stripping to give 47.7 parts by mass of Silicone-C, which corresponds to the epoxy group-containing organopolysiloxane of the present invention. This was a white solid and had an epoxy equivalent of 6100 g/mol and a weight average molecular weight of 13500.

Example 4

(5) Into a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel, 100 parts by mass of 50% solution of organohydrogenpolysiloxane in isododecane was introduced, together with 0.1 parts by mass of 0.5 mass % solution of platinum catalyst in toluene, with the organohydrogenpolysiloxane having the average composition formula (2) in which R.sup.1 was a methyl group, R.sup.3 was a hydrogen atom, the SiH group content was 0.233 mol/100 g, and (a+b)/(c+d)=0.7, and having a weight average molecular weight of 13000. This mixture was heated to 80 C., and then 15.5 parts by mass of allyl glycidyl ether was introduced into the dropping funnel and dropped to the mixture over 10 minutes. After finishing the dropping, this was stirred for 7 hours at 80 C. At this time, the progress of reaction was confirmed by .sup.1H-NMR in which the peak of hydrosilyl group (4.6 to 4.8 ppm) almost disappeared and a new peak of silethylene (0.5 to 0.7 ppm) occurred. The reaction solution was cooled to room temperature and treated with activated charcoal, followed by filtration. Then, the volatile components were removed by stripping to give 56.2 parts by mass of Silicone-D, which corresponds to the epoxy group-containing organopolysiloxane of the present invention. This was a white solid and had an epoxy equivalent of 650 g/mol and a weight average molecular weight of 17500.

Example 5

(6) Into a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a dropping funnel, 100 parts by mass of 50% solution of organohydrogenpolysiloxane in isododecane was introduced, together with 0.1 parts by mass of 0.5 mass % solution of platinum catalyst in toluene, with the organohydrogenpolysiloxane having the average composition formula (2) in which R.sup.1 was a methyl group, R.sup.3 was a hydrogen atom, the SiH group content was 0.242 mol/100 g, and (a+b)/(c+d)=0.7, and having a weight average molecular weight of 4000. This mixture was heated to 80 C., and then 18.1 parts by mass of 1,2-epoxy-4-vinylcyclohexane was introduced into the dropping funnel and dropped to the mixture over 10 minutes. After finishing the dropping, this was stirred for 7 hours at 80 C. At this time, the progress of reaction was confirmed by .sup.1H-NMR in which the peak of hydrosilyl group (4.6 to 4.8 ppm) almost disappeared and a new peak of silethylene (0.5 to 0.7 ppm) occurred. The reaction solution was cooled to room temperature and treated with activated charcoal, followed by filtration. Then, the volatile components were removed by stripping to give 61.2 parts by mass of Silicone-E, which corresponds to the epoxy group-containing organopolysiloxane of the present invention. This was viscous liquid and had an epoxy equivalent of 650 g/mol and a weight average molecular weight of 6000.

Example 6

(7) To 200 parts by mass of 50% solution of Silicone-A (synthesized in Example 1) in isododecane, 1 part by mass of bis[4-n-alkyl (C.sub.10 to C.sub.13)-phenyl]iodonium hexafluoroantimonate was added. This was well stirred to give a coating material, which corresponds to the ultraviolet curable silicone composition of the present invention. This coating material was applied to a glass plate so as to form a cured film with a thickness of 20 m, and the isododecane was volatilized in a drier at 60 C. Then, this was introduced into a high-pressure mercury-vapor lamp (UV irradiation apparatus manufactured by EYE GRAPHICS CO. LTD.) with irradiation energy of 400 mJ/cm.sup.2 (the irradiation energy at the region of 365 nm measured with a UV meter UVPF-Al manufactured by EYE GRAPHICS CO. LTD.) and cured thereby to prepare a test piece. The obtained coating was transparent and free from tackiness.

Example 7

(8) To 200 parts by mass of 50% solution of Silicone-B (synthesized in Example 2) in isododecane, 1 part by mass of bis[4-n-alkyl (C.sub.10 to C.sub.13)-phenyl]iodonium hexafluoroantimonate was added. This was well stirred to give a coating material, which corresponds to the ultraviolet curable silicone composition of the present invention. This coating material was applied to a glass plate so as to form a cured film with a thickness of 20 m, and the isododecane was volatilized in a drier at 60 C. Then, this was introduced into a high-pressure mercury-vapor lamp (UV irradiation apparatus manufactured by EYE GRAPHICS CO. LTD.) with irradiation energy of 400 mJ/cm.sup.2 (the irradiation energy at the region of 365 nm measured with a UV meter UVPF-A1 manufactured by EYE GRAPHICS CO. LTD.) and cured thereby. The obtained coating was transparent and free from tackiness.

Example 8

(9) To 200 parts by mass of 50% solution of Silicone-C (synthesized in Example 3) in isododecane, 1 part by mass of bis[4-n-alkyl (C.sub.10 to C.sub.13)-phenyl]iodonium hexafluoroantimonate was added. This was well stirred to give a coating material, which corresponds to the ultraviolet curable silicone composition of the present invention. This coating material was applied to a glass plate so as to form a cured film with a thickness of 20 m, and the isododecane was volatilized in a drier at 60 C. Then, this was introduced into a high-pressure mercury-vapor lamp (UV irradiation apparatus manufactured by EYE GRAPHICS CO. LTD.) with irradiation energy of 400 mJ/cm.sup.2 (the irradiation energy at the region of 365 nm measured with a UV meter UVPF-A1 manufactured by EYE GRAPHICS CO. LTD.) and cured thereby. The obtained coating was transparent and free from tackiness.

Example 9

(10) To 200 parts by mass of 50% solution of Silicone-D (synthesized in Example 4) in isododecane, 1 part by mass of bis[4-n-alkyl (C.sub.10 to C.sub.13)-phenyl]iodonium hexafluoroantimonate was added. This was well stirred to give a coating material, which corresponds to the ultraviolet curable silicone composition of the present invention. This coating material was applied to a glass plate so as to form a cured film with a thickness of 20 m, and the isododecane was volatilized in a drier at 60 C. Then, this was introduced into a high-pressure mercury-vapor lamp (UV irradiation apparatus manufactured by EYE GRAPHICS CO. LTD.) with irradiation energy of 400 mJ/cm.sup.2 (the irradiation energy at the region of 365 nm measured with a UV meter UVPF-Al manufactured by EYE GRAPHICS CO. LTD.) and cured thereby to prepare a test piece. The obtained coating was transparent and free from tackiness.

Example 10

(11) To 100 parts by mass of 50% solution of Silicone-A (synthesized in Example 1) in isododecane as well as 50 parts by mass of a mixture of 2,4,6,8-tetramethyl-2,4-bis[2-(7-oxabicyclo[4.1.0]heptane-3-yl)ethyl]-6,8-dipropylcyclotetrasiloxane and 2,4,6,8-tetramethyl-2,6-bis[2-(7-oxabicyclo[4.1.0]heptane-3-yl)ethyl]-4,8-dipropylcyclotetrasiloxane, 1 part by mass of bis[4-n-alkyl (C.sub.10 to C.sub.13)-phenyl]iodonium hexafluoroantimonate was added. This was well stirred to give a coating material, which corresponds to the ultraviolet curable silicone composition of the present invention. This coating material was applied to a glass plate so as to form a cured film with a thickness of 20 m, and the isododecane was volatilized in a drier at 60 C. Then, this was introduced into a high-pressure mercury-vapor lamp (UV irradiation apparatus manufactured by EYE GRAPHICS CO. LTD.) with irradiation energy of 400 mJ/cm.sup.2 (the irradiation energy at the region of 365 nm measured with a UV meter UVPF-Al manufactured by EYE GRAPHICS CO. LTD.) and cured thereby to prepare a test piece. The obtained coating was transparent and free from tackiness.

(12) Incidentally, the epoxy equivalent of the mixture of Silicone-A, 2,4,6,8-tetramethyl-2,4-bis[2-(7-oxabicyclo[4.1.0]heptane-3-yl)ethyl]-6,8-dipropylcyclotetrasiloxane, and 2,4,6,8-tetramethyl-2,6-bis[2-(7-oxabicyclo[4.1.0]heptane-3-yl)ethyl]-4,8-dipropylcyclotetrasiloxane was 475 g/mol at the mixing.

Example 11

(13) To 50 parts by mass of 50% solution of Silicone-A (synthesized in Example 1) in isododecane as well as 75 parts by mass of a mixture of 2,4,6,8-tetramethyl-2,4-bis[2-(7-oxabicyclo[4.1.0]heptane-3-yl)ethyl]-6,8-dipropylcyclotetrasiloxane and 2,4,6,8-tetramethyl-2,6-bis[2-(7-oxabicyclo[4.1.0]heptane-3-yl)ethyl]-4,8-dipropylcyclotetrasiloxane, 1 part by mass of bis[4-n-alkyl (C.sub.10 to C.sub.13)-phenyl]iodonium hexafluoroantimonate was added. This was well stirred to give a coating material, which corresponds to the ultraviolet curable silicone composition of the present invention. This coating material was applied to a glass plate so as to form a cured film with a thickness of 20 m, and the isododecane was volatilized in a drier at 60 C. Then, this was introduced into a high-pressure mercury-vapor lamp (UV irradiation apparatus manufactured by EYE GRAPHICS CO. LTD.) with irradiation energy of 400 mJ/cm.sup.2 (the irradiation energy at the region of 365 nm measured with a UV meter UVPF-Al manufactured by EYE GRAPHICS CO. LTD.) and cured thereby to prepare a test piece. The obtained coating was transparent and free from tackiness.

(14) Incidentally, the epoxy equivalent of the mixture of Silicone-A, 2,4,6,8-tetramethyl-2,4-bis[2-(7-oxabicyclo[4.1.0]heptane-3-yl)ethyl]-6,8-dipropylcyclotetrasiloxane, and 2,4,6,8-tetramethyl-2,6-bis[2-(7-oxabicyclo[4.1.0]heptane-3-yl)ethyl]-4,8-dipropylcyclotetrasiloxane was 388 g/mol at the mixing.

Comparative Example 1

(15) To 100 parts by mass of a mixture of 2,4,6,8-tetramethyl-2,4-bis[2-(7-oxabicyclo[4.1.0]heptane-3-yl)ethyl]-6,8-dipropylcyclotetrasiloxane and 2,4,6,8-tetramethyl-2,6-bis[2-(7-oxabicyclo[4.1.0]heptane-3-yl)ethyl]-4,8-dipropylcyclotetrasiloxane (epoxy equivalent: 300 g/mol), 1 part by mass of bis[4-n-alkyl (C.sub.10 to C.sub.13)-phenyl]iodonium hexafluoroantimonate was added, and this mixture was well stirred. This coating material was applied to a glass plate so as to form a cured film with a thickness of 20 Then, this was introduced into a high-pressure mercury-vapor lamp (UV irradiation apparatus manufactured by EYE GRAPHICS CO. LTD.) with irradiation energy of 400 mJ/cm.sup.2 (the irradiation energy at the region of 365 nm measured with a UV meter UVPF-A1 manufactured by EYE GRAPHICS CO. LTD.) and cured thereby to prepare a test piece. The obtained coating was transparent and free from tackiness.

Comparative Example 2

(16) To 100 parts by mass of epoxy group-containing organopolysiloxane shown by the following formula (3) (epoxy equivalent: 1500 g/mol), 1 part by mass of bis[4-n-alkyl (C.sub.10 to C.sub.13)-phenyl]iodonium hexafluoroantimonate was added, and this mixture was well stirred. This coating material was applied to a glass plate so as to form a cured film with a thickness of 20 This was introduced into a high-pressure mercury-vapor lamp (UV irradiation apparatus manufactured by EYE GRAPHICS CO. LTD.) with irradiation energy of 400 mJ/cm.sup.2 (the irradiation energy at the region of 365 nm measured with a UV meter UVPF-A1 manufactured by EYE GRAPHICS CO. LTD.), but was cured insufficiently to give coating partly having tackiness.

(17) ##STR00008##

(18) In Examples and Comparative Examples described above, each property was measured and evaluated by the following methods. The results are shown in Table 1.

(19) (1) Method of Measuring Properties of Compounds

(20) (1.1) Weight Average Molecular Weight

(21) The weight average molecular weight was measured for a solution of a certain mass of each sample diluted with a solvent to concentration of 0.3 mass % using a liquid chromatography HLLC-8220GPC manufactured by TOSOH CORPORATION, which was corrected for molecular weight in terms of standard polystyrene. For epoxy group-containing organopolysiloxane shown by the average composition formula (1), THF was used as a solvent; and for organohydrogenpolysiloxane shown by the average composition formula (2), toluene was used as a solvent.

(22) (1.2) Epoxy Equivalent

(23) The epoxy equivalent was calculated by back titration of a certain mass of each sample dissolved in 1,4-dioxane using hydrochloric acid and sodium hydroxide. The titration was performed using an automatic titrator (COM-1750 manufactured by Hiranuma Sangyo Co., Ltd.). In each sample in a solid form, the epoxy equivalent was measured for a sample diluted with each solvent, and the intended value was determined by calculating from the concentration of dilution.

(24) (2) Method of Measuring Properties of Cured Film

(25) (2.1) Appearance of Coating (Transparency of Coating) and State of Curing

(26) The appearance of the cured film (transparency of coating) of each test piece was observed by visual inspection. The state of curing was examined by touching using a finger to evaluate the sample free from tackiness to be good and the sample with tackiness to be bad.

(27) (2.2) Pencil Hardness Test

(28) Onto each test piece placed in a horizontal state, pencils with different hardness was pressed to the coating at an angle of 451 under a loading of 50010 g to measure the hardness of coating.

(29) As shown in the results in Table 1, each silicone composition containing the inventive epoxy group-containing organopolysiloxane (Examples 6 to 11) was excellent in ultraviolet curability, and the cured film thereof was transparent.

(30) TABLE-US-00001 TABLE 1 Epoxy Transparency Pencil equivalent Curability of coating hardness Example 6 650 good transparent 4H Example 7 3300 good transparent unmeasurable Example 8 6100 good transparent unmeasurable Example 9 650 good transparent unmeasurable Example 10 650 (475 good transparent H at mixing) Example 11 650 (388 good transparent HB at mixing) Comparative 300 good transparent B Example 1 Comparative 1500 bad transparent unmeasurable Example 2

(31) The epoxy group-containing organopolysiloxane (3) used in Comparative Example 2 was cured insufficiently by ultraviolet irradiation, and the obtained film partly had tackiness. On the other hand, the inventive epoxy group-containing organopolysiloxane, as Silicone-B and Silicone-C used in Examples 7 and 8, underwent ultraviolet curing even when the epoxy equivalent was larger than that of the epoxy group-containing organopolysiloxane (3) to give transparent coating.

(32) When Comparative Example 1 and Example 6 are compared, Silicone-A used in Example 6 had an epoxy equivalent larger than that of the epoxy group-containing organopolysiloxane used in Comparative Example 1, but the cured film was harder in Example 6 compared to that of Comparative Example 1, showing that higher hardness could be obtained even when the epoxy equivalent was large.

(33) Moreover, addition of the inventive epoxy group-containing organopolysiloxane (Silicone-A) to the epoxy group-containing organopolysiloxane used in Comparative Example 1 (Examples 10 and 11) successfully heightened the hardness of each cured film than in Comparative Example 1 while the epoxy equivalent was larger at mixing compared to that of siloxane mixture in Comparative Example 1.

(34) It is to be noted that the present invention is not limited to the foregoing embodiment. The embodiment is just an exemplification, and any examples that have substantially the same feature and demonstrate the same functions and effects as those in the technical concept described in claims of the present invention are included in the technical scope of the present invention.