NORMAL TEMPERATURE-CURABLE HARD COAT COMPOSITION

Abstract

The present invention is a normal temperature-curable hard coat composition containing at least (A) a polysilazane compound having structures shown by the following formula (1) and (B) an alkoxysilane compound. The ratio of [a] the number of Si—H bonds in the polysilazane compound and [b] the number of alkoxy groups in the alkoxysilane compound is in a range of [b]/[a]=1.5 to 3. The present invention provides the normal temperature-curable hard coat composition which has excellent workability on outdoors, cures at normal temperature, improves surface hardness of plastic materials, and is used as an alternative material to glass.

##STR00001##

Claims

1. A normal temperature-curable hard coat composition comprising at least: (A) a polysilazane compound having structures shown by the following formula (1) ##STR00006## wherein R.sub.1 represents a hydrogen atom, or a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms, each R.sub.1 is identical to or different from one another, the polysilazane compound contains at least one Si—H bond in one molecule, R.sub.2 represents a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms, and each R.sub.2 is identical to or different from one another; and (B) an alkoxysilane compound, wherein a ratio of [a] the number of Si—H bonds in the polysilazane compound and [b] the number of alkoxy groups in the alkoxysilane compound is in a range of [b]/[a]=1.5 to 3.

2. The normal temperature-curable hard coat composition according to claim 1, wherein, in the normal temperature-curable hard coat composition, the polysilazane compound is a methyl polysilazane.

3. The normal temperature-curable hard coat composition according to claim 1, wherein, in the normal temperature-curable hard coat composition, an alkoxy group of the alkoxysilane compound is a methoxy group.

4. The normal temperature-curable hard coat composition according to claim 2, wherein, in the normal temperature-curable hard coat composition, an alkoxy group of the alkoxysilane compound is a methoxy group.

5. The normal temperature-curable hard coat composition according to claim 1, wherein, in the normal temperature-curable hard coat composition, the alkoxysilane compound is aminopropyltrimethoxysilane.

6. The normal temperature-curable hard coat composition according to claim 2, wherein, in the normal temperature-curable hard coat composition, the alkoxysilane compound is aminopropyltrimethoxysilane.

7. The normal temperature-curable hard coat composition according to claim 3, wherein, in the normal temperature-curable hard coat composition, the alkoxysilane compound is aminopropyltrimethoxysilane.

8. The normal temperature-curable hard coat composition according to claim 4, wherein, in the normal temperature-curable hard coat composition, the alkoxysilane compound is aminopropyltrimethoxysilane.

9. The normal temperature-curable hard coat composition according to claim 1, wherein the normal temperature-curable hard coat composition further comprises a condensation curing catalyst selected from compounds containing a titanium or aluminum atom.

10. The normal temperature-curable hard coat composition according to claim 2, wherein the normal temperature-curable hard coat composition further comprises a condensation curing catalyst selected from compounds containing a titanium or aluminum atom.

11. The normal temperature-curable hard coat composition according to claim 3, wherein the normal temperature-curable hard coat composition further comprises a condensation curing catalyst selected from compounds containing a titanium or aluminum atom.

12. The normal temperature-curable hard coat composition according to claim 4, wherein the normal temperature-curable hard coat composition further comprises a condensation curing catalyst selected from compounds containing a titanium or aluminum atom.

13. The normal temperature-curable hard coat composition according to claim 5, wherein the normal temperature-curable hard coat composition further comprises a condensation curing catalyst selected from compounds containing a titanium or aluminum atom.

14. The normal temperature-curable hard coat composition according to claim 6, wherein the normal temperature-curable hard coat composition further comprises a condensation curing catalyst selected from compounds containing a titanium or aluminum atom.

15. The normal temperature-curable hard coat composition according to claim 7, wherein the normal temperature-curable hard coat composition further comprises a condensation curing catalyst selected from compounds containing a titanium or aluminum atom.

16. The normal temperature-curable hard coat composition according to claim 8, wherein the normal temperature-curable hard coat composition further comprises a condensation curing catalyst selected from compounds containing a titanium or aluminum atom.

Description

EXAMPLE

[0063] Hereinafter, the present invention will be specifically described by showing Examples and Comparative Examples, but this invention is not limited to the following Examples. Incidentally, in the following examples, part(s) represent part(s) by mass. In addition, normal temperature means that the temperature condition is in the range of 5 to 35° C. as described in JIS Z 8703:1993.

[0064] The following evaluations were carried out on each composition obtained in Examples 1 to 6 and Comparative Examples 1 to 7.

[Appearance]

[0065] The appearance of each coating film was visually evaluated.

[Pencil Hardness]

[0066] The pencil hardness was measured using a pencil hardness tester (manufactured by Pepaless Co., Ltd.) under a load of 750 g according to JIS K 5600-5-4:1999.

Example 1

[0067] 50 parts of methyl polysilazane as the polysilazane compound, 100 parts of aminopropyltrimethoxysilane as the alkoxysilane compound, and 0.15 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition A. The normal temperature-curable hard coat composition A was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 μm thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found colorless and transparent. Further, the pencil hardness measured on the coating film was 8H.

Example 2

[0068] 50 parts of methyl polysilazane as the polysilazane compound, 125 parts of aminopropyltriethoxysilane as the alkoxysilane compound, and 0.15 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition B. The normal temperature-curable hard coat composition B was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 82 m thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found colorless and transparent. Further, the pencil hardness measured on the coating film was 8H.

Example 3

[0069] 50 parts of methyl polysilazane as the polysilazane compound, 75 parts of aminopropyltrimethoxysilane as the alkoxysilane compound, and 0.13 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition C. The normal temperature-curable hard coat composition C was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 μm thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found colorless and transparent. Further, the pencil hardness measured on the coating film was 8H.

Example 4

[0070] 50 parts of methyl polysilazane as the polysilazane compound, 150 parts of aminopropyltrimethoxysilane as the alkoxysilane compound, and 0.2 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition D. The normal temperature-curable hard coat composition D was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 82 m thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found colorless and transparent. Further, the pencil hardness measured on the coating film was 8H.

Example 5

[0071] 50 parts of methyl/dimethyl polysilazane copolymer (copolymerization ratio 50:50) as the polysilazane compound, 50 parts of aminopropyltrimethoxysilane as the alkoxysilane compound, and 0.07 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition E. The normal temperature-curable hard coat composition E was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 μm thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found colorless and transparent. Further, the pencil hardness measured on the coating film was 8H.

Example 6

[0072] 50 parts of methyl polysilazane as the polysilazane compound and 100 parts of aminopropyltrimethoxysilane as the alkoxysilane compound were mixed without adding the condensation curing catalyst to obtain a normal temperature-curable hard coat composition F. The normal temperature-curable hard coat composition F was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 82 m thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found colorless and transparent. Further, the pencil hardness measured on the coating film was 6H.

Comparative Example 1

[0073] 50 parts of methyl polysilazane as the polysilazane compound, 100 parts of aminopropyltrimethylsilane, and 0.15 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition G. The normal temperature-curable hard coat composition G was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 μm thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found colorless and transparent, but the coating film did not cure.

Comparative Example 2

[0074] 50 parts of methyl polysilazane as the polysilazane compound, 50 parts of aminopropyltrimethoxysilane as the alkoxysilane compound, and 0.1 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition H. The normal temperature-curable hard coat composition H was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 82 m thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found colorless and transparent. In addition, the pencil hardness measured on the coating film was H.

Comparative Example 3

[0075] 50 parts of methyl polysilazane as the polysilazane compound, 200 parts of aminopropyltrimethoxysilane as the alkoxysilane compound, and 0.25 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition I. The normal temperature-curable hard coat composition I was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 82 m thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found cloudy, and the film was uneven depending on locations. In addition, the pencil hardness measured on the coating film was 2H.

Comparative Example 4

[0076] 50 parts of perhydropolysilazane, 200 parts of aminopropyltrimethoxysilane as the alkoxysilane compound, and 0.25 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition J. The normal temperature-curable hard coat composition J was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 82 m thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found cloudy. In addition, the pencil hardness measured on the coating film was H.

Comparative Example 5

[0077] 50 parts of dimethyl polysilazane as the polysilazane compound, 100 parts of aminopropyltrimethoxysilane as the alkoxysilane compound, and 0.15 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition K. The normal temperature-curable hard coat composition K was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 82 m thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found colorless and transparent, but the coating film did not cure.

Comparative Example 6

[0078] 50 parts of dimethyl polysilazane as the polysilazane compound and 0.15 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition L. The normal temperature-curable hard coat composition L was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 82 m thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found colorless and transparent, but the coating film did not cure.

Comparative Example 7

[0079] 100 parts of aminopropyltrimethoxysilane as the alkoxysilane compound and 0.15 parts of dibutoxy(2-oxo-5-oxa-3-heptene-4-yloxy)aluminum (Chelope EB-2, manufactured by Hope Chemical Co., LTD) as the condensation curing catalyst were mixed to obtain a normal temperature-curable hard coat composition M. The normal temperature-curable hard coat composition M was applied to a polycarbonate plate having a thickness of 2 mm such that the composition had a thickness of 50 82 m thereon, and left standing at 25° C. (normal temperature) and 40% RH for 12 hours. After that, the appearance of the coating film was found cloudy, and the coating film was peeled off, which hindered the measurement of the pencil hardness.

[0080] The results of Examples and Comparative Examples are shown in Table 1.

TABLE-US-00001 TABLE 1 Number of alkoxy Polysilazane Alkoxysilane Condensation Curing groups/ After standing Examples & Compound Compound Catalyst Si—H for 12 h Comparative Addition Addition Addition bends Pencil Examples Type amount Type amount Type amount [b]/[a] Appearance Hardness Example 1 Methyl 50 Aminopropyl- 100 Chelope 0.15 2.0 Colorless 8H polysilazane trimethoxy- EB-2 and silane transparent Example 2 Methyl 50 Aminopropyl- 125 Chelope 0.15 2.5 Colorless 8H polysilazane triethoxy- EB-2 and silane transparent Example 3 Methyl 50 Aminopropyl- 75 Chelope 0.13 1.5 Colorless 8H polysilazane trimethoxy- EB-2 and silane transparent Example 4 Methyl 50 Aminopropyl- 150 Chelope 0.2 3.0 Colorless 8H polysilazane trimethoxy- EB-2 and silane transparent Example 5 Methyl/ 50 Aminopropyl- 50 Chelope 0.07 1.7 Colorless 8H dimethyl trimethoxy- EB-2 and Polysilazane silane transparent Copolymer (copolymerization ratio 50:50) Example 6 Methyl 50 Aminopropyl- 100 — — 2.0 Colorless 6H polysilazane trimethoxy- and silane transparent Comparative Methyl 50 Aminopropyl- 100 Chelope 0.15 — Colorless n/a Example 1 polysilazane trimethyl- EB-2 and silane transparent Comparative Methyl 50 Aminopropyl- 50 Chelope 0.1 1.0 Colorless  H Example 2 polysilazane trimethoxy- EB-2 and silane transparent Comparative Methyl 50 Aminopropyl- 200 Chelope 0.25 4.0 Cloudy 2H Example 3 polysilazane trimethoxy- EB-2 silane Comparative Perhydropoly 50 Aminopropyl- 200 Chelope 0.25 1.5 Cloudy  H Example 4 silazane trimethoxy- EB-2 silane Comparative Dimethyl 50 Aminopropyl- 100 Chelope 0.15 — Colorless n/a Example 5 polysilazane trimethoxy- EB-2 and silane transparent Comparative Methyl 50 — — Chelope 0.15 — Colorless n/a Example 6 polysilazane EB-2 and transparent Comparative — — Aminopropyl- 100 Chelope 0.15 — Cloudy n/a Example 7 trimethoxy- EB-2 silane

[0081] From the results of Table 1, in Examples 1 to 6 and Comparative Examples 1, 2, 5, 6, the appearance of the coating films was colorless and transparent after being left standing at normal temperature for 12 hours. However, in Comparative Examples 1, 5, and 6, the coating films did not cure, and finger marks were left on the touched coating films. Further, in Comparative Examples 3, 4, and 7, the appearance of the coating films was cloudy. The cause of the cloudiness is presumably as follows: in Comparative Examples 3 and 7, since the amount of the alkoxy groups is too large, self-condensation of the alkoxy groups themselves occurs; the molecules three-dimensionally grow; and uniformity of the coating films lowers. These cause the cloudiness. In contrast, in Comparative Example 4, since perhydropolysilazane without hydrocarbon groups has the too fast dehydrogenation reaction, the non-uniform coating film is presumably made.

[0082] Next, the pencil hardness in Examples 1 to 5 was 8H, and that in Example 6 was 6H. The film of Example 6 without film condensation curing catalyst cured at normal temperature as well, and exhibited sufficient hardness. Since the pencil hardness of the polycarbonate plate used as the substrate was 2B, it was confirmed that the application of the inventive normal temperature-curable hard coat compositions dramatically improved the surface hardness at normal temperature.

[0083] On the other hand, the pencil hardness was H in Comparative Examples 2 and 4 and 2H in Comparative Example 3. Slight improvement of the pencil hardness was observed, but the surface hardness was insufficient depending on the usage environment. Further, the appearance of the coating films in Comparative Examples 3 and 4 was cloudy, and the coating films cannot be used for transparent materials, such as polycarbonate or acrylic. Particularly, the coating films for use as an alternative material to glass exhibits inappropriate appearance. In Comparative Examples 1 and 5 to 7, the coating films were not cured or were peeled off from the substrate. Therefore, the pencil hardness was not evaluated.

[0084] From the above results, the normal temperature-curable hard coat compositions obtained in Examples 1 to 6 sufficiently cured at normal temperature in 12 hours, and the coating films had the colorless and transparent appearance. Further, the pencil hardness on the polycarbonate of the coating films was 6H or more.

[0085] It should be noted that the present invention is not limited to the above-described embodiments. The embodiments are just examples, and any embodiments that substantially have the same feature and demonstrate the same functions and effects as those in the technical concept disclosed in claims of the present invention are included in the technical scope of the present invention.