In some embodiments, the filler can include inorganic and/or metal oxide particles, glass fibers, carbon blacks, carbon nanotubes and/or metallic fillers. The inorganic oxides and/or metal oxides can include, for example, silicon oxides, aluminum oxides, titanium oxides, zinc oxides, germanium oxides, indium oxides, tin oxides, zirconium oxides, antimony oxides and/or combinations thereof.

In some embodiments, the coating composition can be mixed and applied from alcoholic solvents, such as methanol, ethanol, propanol, isopropanol, butanol and its isomers to clear or optically transparent plastic films, sheets, or substrates via flow coating, dip coating, roll coating, spray coating, knife coating, or flooding. Printing processes, dipping, transfer processes and brushing can also be used.

In some embodiments, the clear or optically transparent plastic film, sheet, or substrate can include a thermoplastic polymer, such as ABS, AMMA, ASA, CA, CAB, EP, UF, CF, MF, MPF, PF, PAN, PA, PE, HDPE, LDPE, LLDPE, PC, PET, PMMA, PP, PS, SB, PUR, PVC, RF, SAN, PBT, PPE, POM, PP-EPDM and UP (abbreviations in accordance with DIN 7728 part 1) and mixtures thereof, as well as laminated films constructed from two or more layers of these plastics. In general, films, sheets, or substrates to be used according to the invention may also contain reinforcing fibers or fabrics, provided that these do not impair the desired thermoplastic deformation.

Particularly suitable are thermoplastic polyurethanes, polymethyl methacrylate (PMMA) and modified variants of PMMA, as well as polycarbonate (PC), ASA, PET, PP, PP-EPDM and ABS.

The composition described herein can be coated on one or both sides of the film, sheet, or substrate. In the case of single-sided coating, a thermally deformable adhesive layer may optionally be applied to the reverse of the film, i.e., to the surface on which the coating composition has not been applied. Depending on the method, hot-melt adhesives or radiation-curing adhesives are suitable for this purpose. In addition, a protective film which is likewise thermally deformable may also be applied on to the surface of the adhesive layer. It is further possible to provide the reverse of the film with support materials such as fabrics, but these should be deformable to the desired extent.

Before or after applying the composition, the sheet, film, or substrate may optionally be lacquered or printed with one or more layers. This may take place on the coated or on the uncoated side of the film. The layers may be colored or functional, and applied over the entire surface or only part thereof, e.g., as a printed image. The lacquers used should be thermoplastic so that they do not crack during subsequent deformation. Printing inks as commercially available for so-called “in-mold decoration” processes can be used.

Once the coating composition is applied to the film, sheet, or substrate the solvent can be evaporated and the coating dried. For this purpose, drying can be carried out particularly at elevated temperatures in ovens, e.g., convection ovens, jet dryers, as well as heat radiation (IR, NIR). It is possible and advantageous to combine several of these drying processes. The conditions for drying are advantageously selected such that no unblocking and polymerization (crosslinking) of the isocyanate groups is triggered by the elevated temperature and/or heat radiation, since this can have a negative effect on thermoformation. Furthermore, the maximum temperature reached should usefully be selected to be sufficiently low that the film does not deform in an uncontrolled manner.

The applied coating can be initially cured via actinic radiation, e.g., UV radiation, to form a tack free coating that remains pliable yet resists damage due to handling of the coated article. Curing with actinic radiation is understood to be the free-radical polymerization of ethylenically unsaturated carbon-carbon double bonds of the acrylate and/or methacrylate by means of initiator radicals which are released by irradiating with actinic radiation, e.g., from the photoinitiators described above.

The radiation curing can take place through the impact of high-energy radiation, i.e., UV radiation or daylight, e.g., light at a wavelength of about 200 nm to about 750 nm, or by irradiating with high-energy electrons (electron beam, e.g., of about 90 keV to about 300 keV). Examples of radiation sources for light or UV light are medium- or high-pressure mercury vapor lamps, wherein the mercury vapor may be modified by doping with other elements such as gallium or iron. Lasers, pulsed lamps (known as UV flash lamps), halogen lamps or excimer lamps may also be used. The lamps may be installed in a fixed position so that the coating to be irradiated is moved past the radiation source using a mechanical device, or the lamps may be movable and the coating to be irradiated does not change its position during the curing. The radiation dose generally sufficient for crosslinking with UV curing is in the range of about 80 mJ/cm²to about 5000 mJ/cm².

The irradiation may optionally also take place with the exclusion of oxygen, e.g., under an inert gas atmosphere or oxygen-reduced atmosphere. Suitable as inert gases are preferably nitrogen, carbon dioxide, noble gases or combustion gases. Furthermore, the irradiation can take place by covering the coating with media which are transparent to radiation. Examples of these are e.g., polymer films, glass, or liquids.

The actinic radiation cured coating can be deformable and/or flexible and tack-free. In some embodiments, the tack-free, deformable coating has a glass transition temperature (Tg) of about 38° C. to about 115° C., about 60° C. to about 100° C., or about 80° C. to about 100° C. and a tanδ of about 1.7 to about 3.30, 1.8 to about 3.0, or about 1.9 to about 2.6.

Following actinic radiation curing the coated substrate can be dried to remove water absorbed by the coated substrate at temperatures and times sufficient to remove the absorbed water. The coated substrate can then be heated at an elevated temperature effective to unblock the isocyanate groups and thereby start the second cross linking reaction while also heating the article to a temperature that allows successful forming of the article to the desired shape. By way of example, the coated substrate can be exposed to elevated temperatures greater than 115° C. for 5 to 120 minutes to unblock the isocyanate groups and initiate a urethane exothermic condensation reaction, which further crosslinks the coating.

In some embodiments, the coated substrate can exposed to elevated temperatures during thermoforming, vacuum forming, or compression molding the coated substrate into a desired three dimensional shape.

The resulting dual cured coating exhibits good resistances to solvents and staining liquids as found in the household, as well as high hardness, good scratch resistance and good abrasion resistance with high optical transparency. For example, the rigid, abrasion resistant coating can be substantially crack-free and have a total light transmittance of at least about 80%, at least about 81%, at least about 82%, at least about 83%, at least about 84%, at least about 85%, at least about 86%, at least about 87%, at least about 88%, at least about 89%, at least about 90%, or more as measured at a wavelength of 400 to 700 nm in accordance with ASTM D1003, a delta haze in accordance with ASTM D1003 of about 8.0% or less, a yellow index in accordance with ASTM E313 of 3 or less and an adhesion of at least 3B, 4B, or 5B in accordance with ASTMD3359. In some embodiments the dual cured, rigid, abrasion resistant coating has a temperature (Tg) of about 80° C. to about 130° C., about 90° C. to about 125° C., or about 115° C. to about 125° C. and a tanδ of about 0.50 to about 2.50, about 0.7 to about 2.45, or about 1.48 to about 2.45.

In some embodiments, a film, sheet, or substrate coated with the composition can be used for the production of shaped articles, such as for the production of consumer articles including vehicle add-on parts, plastics parts, such as panels for vehicle (interior) construction and/or aircraft (interior) construction, furniture construction, electronic devices, communication devices, housings, and decorative articles.

Other embodiments described herein relate to an article coated with a coating composition described herein that is processed in flat sheet form, film or sheet, using actinic radiation to cure to a tack free and easily handleable state; that is subsequently dried, heated and formed to a 3D geometry using drape or thermoforming techniques.

In some embodiments, the article is formed into a protective visor that has abrasion and chemical resistant properties.

In some embodiments, the article is formed into a windshield for a motorcycle, side by side or ATV that has abrasion and chemical resistant properties.

In some embodiments, the article is formed into a roof or door system that exhibits abrasion and chemical resistant properties.

In some embodiments, the article is formed into a window or multi-layer laminate system for construction or substantially equivalent applications.

In some embodiments, the article is formed using an in mold decoration process to produces lenses, decorative automotive trim or substantially similar item.

In some embodiments, the article is formed into a protective visor or lens faceplate that exhibits abrasion and chemical resistant properties.

Other embodiments described herein relate to a thermoformable coating that can be cast from non-toxic solvents, which are not likely to attack plastic materials used for clear glazing materials and which can be cured to a tack free state using actinic radiation and formed into complex parts.

The following examples are included to demonstrate various aspects of the invention. Those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific aspects which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

EXAMPLES

Standard Sheet Drying Procedure

Samples of 0.220″ thickness polycarbonate sheet were placed into a convection oven at 115° C. for 12 hours to lower the moisture content of the sheet such that bubbles will not form in the sheet during forming operations.

Standard Thermo-Forming Procedure:

Samples of 0.220″ thickness polycarbonate sheet, which had already been dried, were placed in a convection oven heated to 175° C. for 20 minutes, or until pliable, then formed around 10-inch diameter mold to evaluate for cracks, delamination or other undesirable optical effects.

Comparative Example 1

25 grams of a commercial UV curable abrasion resistant coating was diluted to 20 wt % solids with 1-methoxy-2-propanol and stirred until a uniform solution resulted. This coating was applied to both sides of a 0.220″ thickness polycarbonate plaque, allowed to flash at 25° C. for 5 minutes, heated at 55° C. for 60 seconds and cured with a 600 Watt per Inch H-type lamp. This coated panel exhibited excellent adhesion (5B ASTM D3359) good scratch and abrasion resistance (2 to 3% delta haze after 100 cycles with CS10F taber abrader wheel per ASTM D1003). This coated plaque was heated at 115° C. for 10 hours to remove moisture from the polycarbonate sheet, then heated to 175° C. for 20 minutes or until the sheet was pliable. This sheet was then dried, formed and evaluated for damage to the coating. There were multiple longitudinal cracks apparent in the coating and the formed part was not judged to be useful for any optical applications.

Comparative Example 2

25 grams of a commercial UV curable abrasion resistant coating, more flexible than in Comparative Example 1, was diluted to 20 wt % solids with 1-methoxy-2-propanol and stirred until a uniform solution resulted. This coating was applied to both sides of a 0.220″ thickness polycarbonate plaque, allowed to flash at 25° C. for 5 minutes, heated at 125° C. for 90 seconds and cured with a 600 Watt per Inch H-type lamp. This coated panel exhibited excellent adhesion (5B ASTM D3359) good scratch and abrasion resistance (6 to 8% delta haze after 100 cycles with CS10F taber abrader wheel per ASTM D1003). This sheet was then dried, formed and evaluated for damage to the coating. There were multiple longitudinal cracks apparent in the coating and the formed part was not judged to be useful for any optical applications.

The coating was applied to both sides of a thin substrate (0.005″) using a 16 mayer rod, cured using UV radiation. A sample measuring approximately 13 mm wide, by 30 mm long and 0.15 mm thickness was mounted in a single cantilever attachment for a Hitachi DMA7100 and subjected to a ramp from −85° C. to 150° C. at 10° C./min and subjected to a sinusoidal force at 1 Hz. The measured Tg (peak Tanδ) for the UV cured sample was 105° C. and Tanδ was 1.77. The same sample was subjected to a second cycle to measure the change in thermal properties of the sample. The second Tg (peak tanδ) was 112° C. with a corresponding tanδ of 1.45.

Inventive Example 1

While stirring 24.86 grams of hexafunctional urethane acrylate with pendant hydroxyl groups (hydroxyl equivalent weight 660 grams per mole), 10.07 grams of blocked hexamethylene diisocyanate biuret (isocyanate equivalent weight 410 grams per mole) and 1-methoxy-2-propanol were added, along with 24.80 grams of a urethane diacrylate with pendant hydroxyl groups (hydroxyl equivalent weight ~2100 grams per mole), 5.27 grams of a tetrafunctional polyol derived from caprolactone (hydroxyl equivalent weight 257 grams/mole), 2.50 grams of an amine acrylate synergist, 1.59 grams of a benzophenone derived photoinitiator and 0.12 grams of dibutyl tin dilaurate catalyst. This mixture was diluted to 20 wt % solids with 1-methoxy-2-propanol and stirred until a clear low viscosity solution resulted. A 0.220″ thickness polycarbonate plaque was coated and dried at 25° C. for 5 minutes, then placed into an oven at 75° C. for 60 seconds, subjected to actinic radiation (approximately 800 to 1500 mJ/cm2 UVA, 1000 mJ/cm²UVB and 600 mJ/cm2 UVC) to effect cure. The coated panel was dry and tack free and exhibited moderate abrasion resistance when handled. This part was dried, formed and evaluated for damage to the coating. This coated part showed resistance to scratching with #0000 steel wool, no cracks developed and exhibited 5B adhesion according to ASTM D3359

Inventive Example 2

While stirring 9.48 grams of urethane diacrylate with pendant hydroxyl groups (hydroxyl equivalent weight 2100 grams per mole), 7.76 grams of blocked hexamethylene diisocyanate biuret and 3.64 grams of tetrafunctional polyol were added (hydroxyl equivalent weight 257 grams/mol), photoinitiators and DBTDL were added. This solution was diluted to 20 wt % solids with 1-methoxy-2-propanol, stirred until clear and applied to 0.220″ thickness polycarbonate panel and dried for 5 minutes at 25° C. This part was subjected to actinic radiation. Upon evaluation, the coating was very soft and appeared to have no wet film strength, in that mud cracks had developed in the coating during the UV curing process.

Inventive Example 3

While stirring 692.4 grams of a hexafunctional urethane acrylate with pendant hydroxyl groups (hydroxyl equivalent weight 660 gr/mol), 907.2 of a blocked hexamethylene diisocyanate biuret and 405 grams of a caprolactone derived tetrafunctional polyols were added. Once this was thoroughly mixed, 180 grams of photoinitiator were added followed by 10 grams of dibutyl tin dilaurate catalyst. This mixture was stirred until a clear solution resulted then diluted to approximately 20 wt % solids in 1-methoxy-2-propanol and coated onto 0.220″ polycarbonate panels. The resulted parts were exposed to actinic radiation to effect cure and allow handling of the parts in a tack free state. These parts where then dried at 115° C. for 12 hours in a recirculation air oven to dry to polycarbonate, then heated to 170° C. for 5 minutes wherein the polycarbonate became flexible and was formed to a 3″ plastic core (1.5″ radius). The coated part remained clear and exhibited no cracking or loss of adhesion of the coating to the polycarbonate panels.

Inventive Example 4

To a container containing 21.46 grams of a commercially available urethane acrylate oligomer isocyanate functional resin (NCO equivalent weight 344 grams per mol) 5.9652 grams of 3,5 dimethyl pyrazole were added with stirring. The container was heated at 65° C. for 3 hours with the extent of reaction of the isocyanate with the active amine compound monitored by FTIR spectroscopy. Upon disappearance of the isocyanate peak in the IR spectrum, the isocyanate was considered blocked and was used in our tests. This new blocked isocyanate 4.88 grams (equivalent weight 525 grams per mol) was added to 6.64 grams of an hexa-acrylated polyol (equivalent weight 660 grams per mole) and 0.85 grams of a catalyst mixture to allow photo and thermal curing. This mixture was added to 46 grams of methoxy propanol, mixed thoroughly and coated onto a polycarbonate panel, allowed to flash off for 5 minutes at room temperature, heated at 90° C. for 60 seconds and cured with actinic radiation. The part was tack free and clear. This part was then heated at 165° C. for 10 minutes and formed around a 3″ plastic mandrel. The part remained clear, had good adhesion and good abrasion resistance without any loss of adhesion or cracking observed in the part. (Example 22 Table 1).

The coating was applied to both sides of a thin substrate (0.005″) using a 16 mayer rod, cured using UV radiation. A sample measuring approximately 14 mm wide, by 30 mm long and 0.15 mm thickness was mounted in a single cantilever attachment for a Hitachi DMA7100 and subjected to a ramp from −85° C. to 150° C. at 10° C./min and subjected to a sinusoidal force at 1 Hz. The measured Tg (peak Tanδ) for the UV cured sample was 63.3° C. and Tanδ was 3.30. The same sample was subjected to a second cycle to measure the change in thermal properties of the sample. The second Tg (peak tanδ) was 89.7° C. with a corresponding tanδ of 2.37.

The following Table lists examples of varying formulations of dual curable coating compositions provided on substrates prepared in accordance with the Examples and the properties of the coatings following actinic radiation curing and thermoforming. Notably, experiments 1-6 and 8-14 were performed using variations of the formulation of the coating composition of Inventive Example 1; experiments 7, 15, and 16 were performed using variations of the formulation of the coating composition of Inventive Example 3, and experiments 17-24 were performed using variations of the formulation of the coating composition of Inventive Example 4. Experiment 25 provides the properties of a coating prepared using coating composition of Comparative Example 2. Experiment 26 lists the Light transmission, haze, and yellowness index of an uncoated substrate.

TABLE

Dual Cure formable coating experiments

4x
HFUA
DFUA

Blocked
polyol
polyol
polyol

Experiment
isocyanate
(257
(660 gr
(2100 gr

#
(NCO eq wt)
OH eq wt)
OH eq wt)
OH eq wt)
Results after forming

1
15 grams
2.2
2.87
43.56
Forming excellent, clear

haze free, 5B, soft

2
15 grams
1.77
2.27
34.40

3
15 grams
4.47
2.87
26.14

4
15 grams
3.39
2.18
19.83
Excellent forming good

abrasion resistance clear

haze free Adhesion 5B

5
15 grams
2.23
11.48
17.43

6
15 grams
1.70
8.75
13.27

7
15 grams
6.70
11.48
0.00
Excellent forming good

abrasion resistance (15)

clear haze free Adhesion

5B UV Tg = 39.6 C.

tanδ = 2.26 Heat

Tg = 111 C.

tanδ = 0.88

8
15 grams
5.10
8.71
4.42

9
15 grams
2.24
2.87
43.56

10
15 grams
1.70
2.17
33.05

11
15 grams
6.70
2.87
8.78
Developed mud cracks

during drying, soft, clear