WO2021038427A1

WO2021038427A1 - Uv protection agent, and laminate having uv protection layer using same

Info

Publication number: WO2021038427A1
Application number: PCT/IB2020/057906
Authority: WO
Inventors: Taiki IHARA; Naota SUGIYAMA; Yoshihiro Kashihara
Original assignee: 3M Innovative Properties Company
Priority date: 2019-08-29
Filing date: 2020-08-24
Publication date: 2021-03-04
Also published as: JP2021030691A

Abstract

The present disclosure relates to a UV protection agent containing a combination of core-shell type inorganic nanoparticles and an organic UV absorbing agent, and a laminate having a UV protection layer using the UV protection agent. The core-shell type inorganic nanoparticle has a core part containing zinc oxide or titanium oxide and a shell part containing silicon dioxide (silica).

Description

UV PROTECTION AGENT, AND LAMINATE HAVING UV PROTECTION LAYER USING SAME

Technical Field

The present disclosure relates to a UV protection agent containing a combination of core shell type inorganic nanoparticles and an organic UV absorbing agent, and a laminate having a UV protection layer using the UV protection agent.

Background Art

Nanoparticles of inorganic materials, such as metal oxides, include nanoparticles having various functionalities. For example, nanoparticles of zinc oxide (ZnO) and titanium dioxide (T1O2) have been known as being useful for protection against ultraviolet radiation having a wavelength up to approximately 360 nm. For example, patent document JP 2010-261012 A proposes a UV-shielding coating composition containing composite zinc oxide fine particles obtained by coating surfaces of zinc oxide fine particles with at least one selected from the group consisting of oxides and hydroxides of Al, Si, Zr, and Sn. Furthermore, among organic UV absorbing agents exemplified by hydroxyphenyltriazine, organic UV absorbing agents that can absorb ultraviolet radiation having a relatively long wavelength (up to approximately 400 nm) have been known.

Summary of Invention

In an aspect, the present disclosure relates to a UV protection agent containing a combination of core-shell type inorganic nanoparticles and an organic UV absorbing agent. The core -shell type inorganic nanoparticle has a core part containing zinc oxide or titanium oxide and a shell part containing silicon dioxide (silica). In another aspect, the present disclosure relates to a laminate having a substrate and a UV protection layer. The UV protection layer contains core-shell type inorganic nanoparticles, an organic UV absorbing agent, and a binder. The core-shell type inorganic nanoparticle has a core part containing zinc oxide or titanium oxide and a shell part containing silicon dioxide.

The present disclosure provides a UV protection agent that achieves protection against ultraviolet radiation having a relatively long wavelength while an object to which the UV protection agent is added does not turn yellow. By using the UV protection agent, a UV protection layer that can achieve protection against ultraviolet radiation having a relatively long wavelength can be provided. Brief Description of Drawings

FIG. 1 is light transmittance spectra of Example 3, Comparative Example 1-2, and Comparative Example 2-3 using TINUVIN 477, and Comparative Example 3-1 using only silica- coated ZnO.

FIG. 2 is light transmittance spectra of Example 7, Comparative Example 1-5, and Comparative Example 2-6 using UVINUL 3050, and Comparative Example 3-1 using only silica- coated ZnO.

FIG. 3 is a graph showing transition of b^* in the case where an organic UV absorbing agent was used alone and where uncoated ZnO or silica-coated ZnO was added to the organic UV absorbing agent.

Description of Embodiments

Technical background of the present disclosure

Nanoparticles of zinc oxide (ZnO) and titanium dioxide (T1O2) have been known as being useful for protection against ultraviolet radiation having a wavelength up to approximately 360 nm. Unfortunately, such nanoparticles have a disadvantage of reducing weather resistance of coatings due to its photocatalytic activity in the case where being blended as UV protection agents in the coatings. On the other hand, in the field of UV protection agents, materials that can deal with the ultraviolet radiation having a relatively long wavelength (up to approximately 400 nm), which is close to the visible radiation region, have been required.

Among organic UV absorbing agents including hydroxyphenyltriazine, organic UV absorbing agents that can absorb ultraviolet radiation having a relatively long wavelength exist; however, such organic UV absorbing agents often turn coatings into yellow in the case where such organic UV absorbing agents are added to the coatings. The present disclosure provides solutions to such problems.

UV protection agent

The core-shell type inorganic nanoparticle contained in the UV protection agent of the present disclosure is a nanoparticle that has at least a core part and a shell part covering the core part and that is substantially formed from inorganic materials. Note that “substantially” in the present specification means, for example, making up 85 wt.% or greater, 90 wt.% or greater, 95 wt.% or greater, or 98 wt.% or greater, of the whole. In an embodiment, the average particle diameter of the core-shell type inorganic nanoparticles is 400 nm or less, 350 nm or less, 300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less, but 10 nm or greater, 20 nm or greater, 30 nm or greater, 40 nm or greater, or 50 nm or greater, and examples of the average particle diameter include a range from 10 nm to 400 nm, from 10 nm to 350 nm, from 10 nm to 300 nm, from 10 nm to 250 nm, from 10 nm to 200 nm, from 10 nm to 150 nm, or from 10 nm to 100 nm. The average particle diameter of the core-shell type inorganic nanoparticles can be identified by, for example, measuring from 500 to 1000 particles by using a transmission electron microscope (TEM) and determining the average thereof.

The core part of the core -shell type inorganic nanoparticle contains zinc oxide (ZnO) or titanium oxide (T1O2). The core part may be substantially formed from zinc oxide or titanium oxide, or may be formed only from zinc oxide or titanium oxide. The core part may be a mixture of zinc oxide and titanium oxide, or a composite metal oxide containing zinc and titanium. In an embodiment, the average diameter of the core parts is 10 nm or greater, 20 nm or greater, 30 nm or greater, 40 nm or greater, or 50 nm or greater, but 400 nm or less, 350 nm or less, 300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less. Specific examples of the average diameter include a range from 25 nm to 100 nm, from 25 nm to 80 nm, from 50 nm to 80 nm, or from 60 nm to 80 nm. The average diameter of the core parts is thought to be substantially the same as the average diameter of the nanoparticles before formation of the shell parts.

The shell part of the core-shell type inorganic nanoparticle contains silicon dioxide (silica, S1O2). The shell part may be substantially formed from silicon dioxide or may be formed only from silicon dioxide. The shell part does not necessarily cover the entire surface of the core part and, for example, has only to cover 50% or greater, 55% or greater, 60% or greater, 65% or greater, 70% or greater, 75% or greater, 80% or greater, 85% or greater, 90% or greater, or 95% or greater, of the surface area of the core part. In an embodiment, the average thickness of the shell parts is 3 nm or greater, 4 nm or greater, 5 nm or greater, 10 nm or greater, 15 nm or greater, 20 nm or greater, 25 nm or greater, or 50 nm or greater. Specific examples of the average thickness include a range from 2 nm to 50 nm, from 2 nm to 25 nm, or from 2 nm to 10 nm. The thickness of the shell part and the like can be measured by using, for example, a transmission electron microscope (TEM).

The core-shell type inorganic nanoparticle can be prepared by, for example, forming the shell part by treating a metal oxide nanoparticle containing zinc oxide or titanium oxide with a silicic acid compound. In an aspect, the present disclosure relates to a production method of the core-shell type inorganic nanoparticles that are combined with an organic UV absorbing agent for use in a UV protection agent. Examples of the silicic acid compound include orthosilicates, such as tetraethyl orthosilicate (TEOS) and tetramethyl orthosilicate (TMOS). The shell part can be formed by preparing an aqueous solvent containing, for example, water, methanol, or ethanol, adding and dispersing metal oxide nanoparticles therein, further adding a silicic acid compound therein, and allowing the mixture to react at a high temperature and a high pressure (e.g., 140°C or higher and 30 atm or higher) for 2 to 3 hours or longer.

It is preferable to modify the metal oxide nanoparticles with amino acids in advance because the shell part can be formed efficiently. As the amino acids used for the modification, an amino acid having an aminoalkyl group is preferred. The aminoalkyl group preferably has a primary amino group at a terminal. In the aminoalkyl group, the number of carbons contained in the alkyl chain is preferably 3 or greater, or 4 or greater. Examples of the preferable aminoalkyl group include an aminopropyl group, an aminobutyl group, an aminopentyl group, and an aminohexyl group. Examples of the preferable amino acids include lysine (L-lysine or D-lysine). The metal oxide nanoparticles can be modified by adding amino acids in a solution obtained by dispersing nanoparticles in an aqueous solvent containing, for example, water, methanol, or ethanol, and agitating at an atmospheric pressure (1 atm) and at 50 to 60°C for 12 hours or longer. Thus, in an embodiment, the core-shell type inorganic nanoparticle contains amino acid, such as lysine, or a derivative or a decomposition product thereof at least in between the core part and the shell part or in the shell part.

The core-shell type inorganic nanoparticle may be further modified with a silane coupling agent after the formation of the shell part. By further modifying the surface of the shell part with a silane coupling agent, for example, in the case of blending in a coating composition, affinity with other components, such as binders (e.g., acrylic resins, urethane resins, epoxy resins, phenol resins, and (poly)vinyl alcohols), is enhanced, and the haze of the formed coating may be reduced. The amount of the silane coupling agent to be used in the modification is preferably an amount that covers the surface of a nanoparticle by substantially a single layer. Such amount of the silane coupling agent can be calculated based on the specific surface area of the nanoparticles and the area that can be covered by a unit amount of the silane coupling agent. The amount of the silane coupling agent is, for example, in a range from 0.5 to 40 wt.%, from 0.5 to 20 wt.%, from 0.5 to 10 wt.%, from 0.5 to 5 wt.%, or from 0.5 to 2 wt.%, relative to the weight of the nanoparticles. Examples of the silane coupling agent include 3 -methacryloxypropyltrimethoxy silane (available under the trade name “SILQUEST A-174”), isooctyltrimethoxysilane, N-(3- triethoxysilylpropyl)methoxyethoxyethoxyethyl carbamate, polyalkyleneoxide alkoxysilane (available under the trade name “SILQUEST A1230”), N-(3- triethoxysilylpropyl)methoxyethoxyethoxyethyl carbamate, 3- (methacryloyloxy)propyltrimethoxysilane, 3-(acryloxypropyl)trimethoxysilane, 3- (methacryloyloxy)propyltriethoxysilane, 3-(methacryloyloxy)propylmethyldimethoxysilane, 3- (acryloyloxypropyl)methyldimethoxysilane, 3-(methacryloyloxy)propyldimethylethoxysilane, 3- (methacryloyloxy)propyldimethylethoxysilane, vinyldimethylethoxysilane, phenyltrimethoxysilane, n-octyltrimethoxysilane, dodecyltrimethoxysilane, octadecyltrimethoxysilane, propyltrimethoxy silane, hexyltrimethoxysilane, vinylmethyldiacetoxysilane, vinylmethyldiethoxysilane, vinyltriacetoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltrimethoxysilane, vinyltriphenoxy silane, vinyltri-t-butoxysilane, vinyltris-isobutoxysilane, vinyltriisopropenoxysilane, vinyltris(2- methoxyethoxy)silane, styrylethyltrimethoxysilane, mercaptopropyltrimethoxysilane, and 3- glycidoxypropyltrimethoxysilane .

Any commercially available organic UV absorbing agent can be used as the organic UV absorbing agent to be combined with the core-shell type inorganic nanoparticles. Examples of the organic UV absorbing agent include hydroxyphenyl triazine (HPT)-based substances (e.g., commercially available from BASF under the trade names TINUVIN 400, TINUVIN 405, TINUVIN 460, TINUVIN 477, and TINUVIN 479), benzotriazole (BTZ)-based substances (e.g., commercially available from BASF under the trade names TINUVIN PS, TINUVIN 99-2, TINUVIN 326, TINUVIN 384-2, TINUVIN 900, TINUVIN 928, TINUVIN 970, and TINUVIN 1130), cyanoacrylate -based substances (e.g., commercially available from BASF under the trade names UVINUF 3035, UVINUF 3039, and UVINUF 3030), and benzophenone -based substances (e.g., commercially available from BASF under the trade names UVINUF 3049, UVINUF 3050, and CHIMAS SORB 81).

In an embodiment, the organic UV absorbing agent preferably has an absorption maximum wavelength in a range from 340 nm to 360 nm from the perspective of sufficiently achieving synergistic effect when the organic UV absorbing agent is combined with the core-shell type inorganic nanoparticles. In another embodiment, the organic UV absorbing agent is preferably a compound having two or more, or three or more, phenolic hydroxyl groups, which is a hydroxyl group bonded to an aromatic hydrocarbon, in one molecule. Examples of such an organic UV absorbing agent include TINUVIN 477, TINUVIN 384-2, TINUVIN 571, and UVINUF 3050. The core-shell type inorganic nanoparticles and the organic UV absorbing agent can be simply combined by mixing the both at ordinary temperature and pressure.

The organic UV absorbing agent may be seen yellow by unaided eye, depending on its absorption characteristics. Furthermore, yellowness is further increased when the organic UV absorbing agent and untreated metal oxide nanoparticles (such as ZnO or T1O2) are mixed to expand the band of the ultraviolet radiation that can be targeted by the protection. However, when the core-shell type inorganic nanoparticles of the present disclosure are used in place of the untreated metal oxide nanoparticles, a UV protection agent that can achieve protection against a wider band of ultraviolet radiation while the yellowness is suppressed can be provided. Laminate

The laminate of the present disclosure has at least a substrate and a UV protection layer. The UV protection layer contains at least core-shell type inorganic nanoparticles, an organic UV absorbing agent, and a binder. The UV protection layer may further contain publicly known additives, including agents that facilitate washing, such as antifog agents, antistatic agents, anti- fingerprint agents, anti-oil agents, anti-lint agents, and antifouling agents, other chemicals that impart functions that facilitate washing, and a combination thereof. The UV protection layer may be in contact with the substrate surface, but a functional layer, such as a primer layer, may be present in between the substrate and the UV protection layer. The UV protection layer is provided on at least one of main surface sides of the substrate, and depending on the situation, the UV protection layers may be provided on the both sides of the two main surfaces, which are opposing each other, of the substrate. Alternatively, an adhesive layer may be provided on a UV protection layer, or provided on a main surface, which is on the opposite side of the UV protection layer, of the substrate. The adhesive layer may contain any publicly known adhesive agents, such as acryl- based adhesive agents, urethane-based adhesive agents, silicone-based adhesive agents, polyester- based adhesive agents, and rubber-based adhesive agents. The thickness of the UV protection layer is, for example, 0.08 pm or greater, 0.2 pm or greater, or 1 pm or greater, but 30 pm or less, 20 pm or less, or 10 pm or less, and may be, for example, in a range of 0.08 pm to 30 pm, 0.08 pm to 20 pm, or 0.08 to 10 pm. Because the UV protection layer contains the core-shell type inorganic nanoparticles, a higher hardness is achieved compared to the case of a UV protection layer that does not contain the core-shell type inorganic nanoparticles. The hardness can be evaluated by, for example, performing an abrasion test using steel wool and measuring the change in haze before and after the test.

The UV protection layer is preferably colorless, transparent, or colorless and transparent. Optical aspects of the UV protection layer can be characterized by, for example, chromaticity b^* of the Lab color system or haze. In an embodiment, a colorless UV protection layer has the chromaticity b^* of the Lab color system of 4.0 or less, 3.9 or less, 3.8 or less, 3.7 or less, 3.6 or less, 3.5 or less, 3.0 or less, 2.5 or less, 2.0 or less, 1.5 or less, 1.0 or less, or 0.5 or less. Furthermore, the chromaticity b^* of the Lab color system of the UV protection layer is lower than chromaticity b^* of a layer formed in the same manner except for using nanoparticles of zinc oxide or titanium oxide in place of the core-shell type inorganic nanoparticles. Without wishing to be bound by theory, it is believed that this is due to the yellowing suppressing effect by the shell part of the core-shell type inorganic nanoparticles. In an embodiment, a transparent UV protection layer has the haze of 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, or 2.5% or less. The haze can be measured by using a haze meter in accordance with JIS K 7361-1 and JIS K 7136. When the surface of the shell part of the core-shell type inorganic nanoparticles is modified with the silane coupling agent, the haze of the UV protection layer using the core-shell type inorganic nanoparticles tends to be low.

In a preferred embodiment, the transmittance at a wavelength of 380 nm of the UV protection layer is 35% or less, 33% or less, 30% or less, 29% or less, 28% or less, 27% or less, 26% or less, 25% or less, or 20% or less. In another embodiment, the wavelength at which the transmittance of the UV protection layer is 20% is in a range from 370 nm to 400 nm, or from 380 nm to 400 nm. In another embodiment, the wavelength at which the transmittance of the UV protection layer is 10% is in a range from 370 nm to 400 nm, or from 380 nm to 400 nm. In another embodiment, the wavelength at which the transmittance of the UV protection layer is 5% is in a range from 370 nm to 400 nm, or from 380 nm to 400 nm. The UV protection layer having such characteristics can provide protection against the ultraviolet radiation having a relatively long wavelength, which is close to the visible radiation region. Note that the UV protection layer of the present disclosure does not allow substantially all light having wavelengths shorter than a certain range to be transmitted. Furthermore, in another embodiment, the transmittance at a wavelength of 430 nm of the UV protection layer is higher than a transmittance at the same wavelength of a layer formed in the same manner except for using nanoparticles of zinc oxide or titanium oxide in place of the core-shell type inorganic nanoparticles, and is 80% or higher. The UV protection layer having such characteristics suppresses yellowing. Note that the transmittance can be measured by using a UV/Vis spectrophotometer.

From the perspective of achieving sufficient UV protection effect, the UV protection layer preferably contains 1 wt.% or greater, 5 wt.% or greater, 10 wt.% or greater, 15 wt.% or greater, or 20 wt.% or greater, of the core-shell type nanoparticles relative to the total weight of the UV protection layer. In an embodiment, the amount of the core-shell type nanoparticles is 90 wt.% or less, 85 wt.% or less, 80 wt.% or less, 75 wt.% or less, 70 wt.% or less, 65 wt.% or less, 60 wt.% or less, 55 wt.% or less, 50 wt.% or less, 45 wt.% or less, 40 wt.% or less, 35 wt.% or less, or 30 wt.% or less, relative to the total weight of the UV protection layer. The range of the amount of the core-shell type nanoparticles is, for example, from 1 to 90 wt.%, from 1 to 50 wt.%, from 1 to 45 wt.%, from 1 to 40 wt.%, from 1 to 35 wt.%, or from 1 to 30 wt.%, relative to the total weight of the UV protection layer. A smaller amount of the core-shell type nanoparticles tends to result in a lower haze of the UV protection layer.

From the perspective of achieving sufficient UV protection effect, the UV protection layer may contain 0.1 wt.% or greater, 0.25 wt.% or greater, 0.5 wt.% or greater, 0.75 wt.% or greater, 1 wt.% or greater, 1.25 wt.% or greater, 1.5 wt.% or greater, 2 wt.% or greater, 2.5 wt.% or greater, 3 wt.% or greater, 3.5 wt.% or greater, 4 wt.% or greater, 4.5 wt.% or greater, or 5 wt.% or greater, of the organic UV absorbing agent relative to the total weight of the UV protection layer. In an embodiment, the amount of the organic UV absorbing agent is, for example, 25 wt.% or less, 20 wt.% or less, 15 wt.% or less, or 10 wt.% or less. The range of the amount of the organic UV absorbing agent is, for example, from 0.1 to 25 wt.%, from 0.1 to 20 wt.%, from 0.1 to 15 wt.%, or from 0.1 to 10 wt.%, relative to the total weight of the UV protection layer. A smaller amount of the organic UV absorbing agent tends to suppress yellowing of the UV protection layer. In an embodiment, the ratio of the organic UV absorbing agent to the core-shell type nanoparticles in the UV protection layer is, in terms of the weight ratio of organic UV absorbing agent/core -shell type nanoparticles, is preferably 0.01 or greater, 0.05 or greater, 0.1 or greater, 0.15 or greater, or 0.2 or greater, but 0.5 or less, 0.45 or less, 0.4 or less, 0.35 or less, or 0.3 or less, and for example, is in a range from 0.01 to 0.5, or from 0.01 to 0.4 from the perspective of balance between the UV protection function and optical characteristics of the UV protection layer.

In an aspect, the present disclosure relates to a formation method of the UV protection layer including application of a coating precursor containing at least the core-shell type inorganic nanoparticles, the organic UV absorbing agent, and the binder.

The UV protection layer can be formed by applying the coating precursor containing at least the core-shell type inorganic nanoparticles, the organic UV absorbing agent, and the binder to a substrate. The coating precursor may contain no organic solvent or may contain an organic solvent depending on the constituents. The coating precursor can be applied by a publicly known coating method, such as bar coating, dip coating, spin coating, capillary coating, spray coating, gravure coating, screen printing, or a combination thereof. The applied coating precursor can be cured by a publicly known polymerization method such as ultraviolet (UV) polymerization or heat polymerization.

For example, as the binder, a UV curable acrylate resin or a thermosetting acrylate resin can be used. Specific examples of the binder include an acrylic resin, a urethane resin, an epoxy resin, a phenol resin, and (poly)vinyl alcohol. More specific examples of the binder include dipentaerythritol pentaacrylate (“SR399”, Sartomer), pentaerythritol triacrylate isophorone diisocyanate (IPDI, “UX5000”, Nippon Kayaku Co., Utd.), urethane acrylate (e.g., “UV1700B” and “UB6300B”, The Nippon Synthetic Chemical Industry Co., Utd., or “EBECRYU8301” and “KRM8528”, Allnex), trimethylhydroxyl diisocyanate/hydroxyethylacrylate (TMHDI/HEA, “EB4858”, Daicel-Cytec Co., Ltd.), polyethylene oxide (PEO)-modified bis-A diacrylate (“R551”, Nippon Kayaku Co., Ltd.), PEO-modified bis-A epoxyacrylate (“3002M”, Kyoeisha Chemical Co., Ltd.), a silane-based UV curable resin (“SK501M”, Nagase ChemteX Corporation), and 2- phenoxyethylmethacrylate (“SR340”, Sartomer); and mixtures thereof. The UV protection layer after the curing may contain 5 wt.% or greater, 10 wt.% or greater, 15 wt.% or greater, or 20 wt.% or greater, but 99 wt.% or less, 95 wt.% or less, 90 wt.% or less, 75 wt.% or less, 60 wt.% or less, 50 wt.% or less, or 40 wt.% or less, of the binder relative to the total weight, and for example, may contain in a range of 95 wt.% to 5 wt.%, 90 wt.% to 10 wt.%, 75 wt.% to 10 wt.%, 60 wt.% to 10 wt.%, 50 wt.% to 10 wt.%, or 40 wt.% to 20 wt.%, of the binder.

In some embodiments, the coating precursor to form the UV protection layer may further contain a crosslinking agent as an optional component. Examples of the crosslinking agent include:

(а) di(meth)acryl -containing compounds, such as 1,3 -butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol monoacrylate monomethacrylate, ethylene glycol diacrylate, alkoxylated aliphatic diacrylate, alkoxylated cyclohexanedimethanol diacrylate, alkoxylated hexanediol diacrylate, alkoxylated neopentyl glycol diacrylate, caprolactone -modified neopentyl glycol hydroxypivalate diacrylate, caprolactone-modified neopentyl glycol hydroxypivalate diacrylate, cyclohexane dimethanol diacrylate, diethylene glycol diacrylate, dipropylene glycol diacrylate, ethoxylated (10) bisphenol A diacrylate, ethoxylated (3) bisphenol A diacrylate, ethoxylated (30) bisphenol A diacrylate, ethoxylated (4) bisphenol A diacrylate, hydroxypivalaldehyde-modified trimethylolpropane diacrylate, neopentyl diacrylate, polyethylene glycol (200) diacrylate, polyethylene glycol (400) diacrylate, polyethylene glycol (600) diacrylate, propoxylated neopentyl glycol diacrylate, tetraethylene glycol diacrylate, tricyclodecane dimethanol diacrylate, triethylene glycol diacrylate, and tripropylene glycol diacrylate; (b) tri(meth)acryl-containing compounds, such as glycerol triacrylate, trimethylolpropane triacrylate, ethoxylated triacrylate (for example, ethoxylated (3) trimethylolpropane triacrylate, ethoxylated

(б) trimethylolpropane triacrylate, ethoxylated (9) trimethylolpropane triacrylate, and ethoxylated (20) trimethylolpropane triacrylate), pentaerythritol triacrylate, propoxylated triacrylate (for example, propoxylated (3) glyceryl triacrylate, propoxylated (5.5) glyceryl triacrylate, propoxylated (3) trimethylolpropane triacrylate, and propoxylated (6) trimethylolpropane triacrylate), trimethylolpropane triacrylate, and tris(2-hydroxyethyl) isocyanurate triacrylate; (c) highly functional (meth)acryl-containing compounds, such as ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, ethoxylated (4) pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, and caprolactone-modified dipentaerythritol hexaacrylate; (d) oligomeric (meth)acrylic compounds, such as urethane acrylate, polyester acrylate, and epoxy acrylate; polyacrylamide analogue of those described above; and poly(meth)acrylic monomers selected from the group consisting of combinations thereof. Examples of the commercially available crosslinking agent include trimethylolpropane triacrylate (TMPTA, “SR351”, Sartomer), pentaerythritol tri/tetraacrylate (PETA, “SR444” or “SR295”, Sartomer), and pentaerythritol pentaacrylate (“SR399”, Sartomer). Furthermore, a mixture of polyfunctional and low functional acrylates, such as a mixture of PETA and phenoxyethyl acrylate (PEA), may be used. The substrate included in the laminate of the present disclosure is not particularly limited, and examples of the substrate include fdms, polymer plates, sheet glass, and metal sheets. A design layer may be provided on a surface of the substrate, or the substrate may be transparent. Examples of the fdm include fdms produced from polycarbonates, poly (meth)acry late s (e.g., polymethylmethacrylates (PMMA)), polyolefins (e.g., polypropylenes (PP)), polyurethanes, polyesters (e.g., polyethylene terephthalates (PET)), polyamides, polyimides, phenolic resins, cellulose diacetates, cellulose triacetates, polystyrenes, styrene-acrylonitrile copolymers, acrylonitrile-butadiene-styrene copolymers (ABS), epoxies, polyethylenes, polyacetates, vinyl chloride, or glass. Examples of the polymer plate include those produced from polycarbonate (PC), polymethylmethacrylate (PMMA), styrene-acrylonitrile copolymers, acrylonitrile-butadiene- styrene copolymers (ABS), blends of PC and PMMA, or laminates of PC and PMMA. The metal sheet may be flexible or rigid. When used in this specification, “flexible metal sheet” indicates a metal sheet that can withstand mechanical stress such as bending or elongation without remarkable irreversible changes, and “hard metal sheet” indicates a metal sheet that cannot withstand mechanical stress such as bending or elongation without remarkable irreversible changes.

Examples of the flexible metal sheet include sheets formed from aluminum. Examples of the hard metal sheet include sheets formed from aluminum, nickel, nickel-chromium, and stainless steel. The typical thickness of the film substrate is in a range of approximately 5 pm to approximately 500 pm. The typical thickness of the polymer plate substrate is from approximately 0.5 mm to approximately 10 mm, approximately 0.5 mm to approximately 5 mm, or approximately 0.5 mm to approximately 3 mm. The typical thickness of the sheet glass or metal sheet substrate is from approximately 5 pm to approximately 500 pm, approximately 5 pm to approximately 100 pm, 5 pm to approximately 50 pm, or approximately 5 pm to approximately 30 pm.

The UV protection layer containing a combination of the core-shell type inorganic nanoparticles and the organic UV absorbing agent according to the present disclosure is useful as a coating for various products for which protection against ultraviolet radiation is desirable. Examples of such a product include home electrical appliances such as vacuum cleaners and laundry machines, furniture, interior materials such as wallpaper, exterior materials such as paint replacement films, optical displays, lenses, mirrors, cellphones, window films, solar panels, and goggles. In particular, the UV protection layer of the present disclosure is useful for the use where colorless and transparent UV protection coating is required, such as optical displays and window films.

The present disclosure encompasses the following embodiments.

(1) A laminate including a substrate and a UV protection layer; the UV protection layer containing a core-shell type inorganic nanoparticle, an organic UV absorbing agent, and a binder; and the core-shell type inorganic nanoparticle having a core part containing zinc oxide or titanium oxide and a shell part containing silicon dioxide.

(2) The laminate according to (1), where chromaticity b^* of Lab color system of the UV protection layer is lower than chromaticity b^* of a layer formed in the same manner except for using a nanoparticle of zinc oxide or titanium oxide in place of the core-shell type inorganic nanoparticle.

(3) The laminate according to (1) or (2), where the organic UV absorbing agent contains a compound having two or more phenolic hydroxyl groups in one molecule.

(4) The laminate according to any one of (1) to (3), where the core-shell type inorganic nanoparticle containing lysine, or a derivative or a decomposition product thereof at least in between the core part and the shell part.

(5) The laminate according to any one of (1) to (4), where a weight ratio of the organic UV absorbing agent to the core-shell type inorganic nanoparticle in the UV protection layer is in a range from 0.01 to 0.5.

(6) The laminate according to any one of (1) to (5), where a transmittance at a wavelength of 380 nm of the UV protection layer is lower than a layer formed in the same manner except for not using the core -shell type inorganic nanoparticle.

(7) The laminate according to any one of (1) to (6), where a wavelength at which the transmittance of the UV protection layer is 20% is in a range from 370 nm to 400 nm.

(8) The laminate according to any one of (1) to (7), where a surface of the shell part of the core-shell type inorganic nanoparticle is modified with a silane coupling agent.

(9) A coating precursor for forming a UV protection coating, including a core-shell type inorganic nanoparticle, an organic UV absorbing agent, and a binder, and the core-shell type inorganic nanoparticle having a core part containing zinc oxide or titanium oxide and a shell part containing silicon dioxide.

(10) A UV protection agent comprising a combination of a core-shell type inorganic nanoparticle and an organic UV absorbing agent, the core-shell type inorganic nanoparticle having a core part containing zinc oxide or titanium oxide and a shell part containing silicon dioxide, and lysine, or a derivative or a decomposition product thereof being contained at least in between the core part and the shell part. Examples

The present invention will be described more specifically below using examples, but the present invention is not intended to be limited to the examples.

Preparation Example 1

(1) Preparation of L-lysine-modified ZnO sol (sol-1)

0.0365 g of L-lysine (FUJIFILM Wako Pure Chemical Corporation) was added to a mixture of 10 g of ZnO sol (AQ-E3913; diameter: 100 nm; Resino Color Industry Co., Ftd.), 25.2 g of methanol, and 4.8 g of distilled water. After agitation was performed at room temperature for 10 minutes, the mixture was agitated for 16 hours in an oil bath at 60°C to obtain an F-lysine- modified ZnO sol (sol-1).

(2) Preparation of silica-coated ZnO sol (sol-3)

To the sol-1, 5.2 g of tetraethyl orthosilicate (TEOS, Wako Pure Chemical Industries, Ltd.) was added. After agitation was performed at room temperature for 10 minutes, the mixture was transferred to an autoclave and heated at 140°C for 5 hours to obtain a sol-2.

Thereafter, using a rotary evaporator, water and methanol of the sol-2 were removed to adjust the solid content to approximately 20 wt.%. l-Methoxy-2 -propanol was added, and a procedure to further remove the remaining water and methanol was repeated twice. By this, a silica-coated ZnO sol (sol-3), in which the silica-coated ZnO particle content in the l-methoxy-2 - propanol was 20 wt.%, was obtained.

(3) Preparation of silane coupling agent-modified silica-coated ZnO sol (sol-4)

To 90.4 g of the sol-2, 0.2235 g of silane coupling agent (“SILQUEST A-174”, 3- methacryloxypropyltrimethoxysilane, Momentive) and 0.0125 g of 4-hydroxy-2, 2,6,6- tetramethylpiperidine-l-oxyl (“PROSTAB”, 5 wt.%, Aldrich) were added and agitated at room temperature for 10 minutes, and then heated in an oven at 60°C for 16 hours. Thereafter, water and methanol were removed by using a rotary evaporator to adjust the solid content to approximately 20 wt.%. 20 g of l-methoxy-2-propanol was added, and a procedure to further remove the remaining water and ethanol was repeated twice. By this, a silane coupling agent-modified silica- coated ZnO sol (sol-4), in which the ZnO nanoparticle content in the l-methoxy-2 -propanol was 20 wt.%, was obtained.

(4) Preparation of uncoated ZnO sol (sol-5)

20 g of ZnO sol (AQ-E3913; diameter: 96 nm; Resino Color Industry Co., Ltd.) and 22.5 g of l-methoxy-2 -propanol were mixed at room temperature for 10 minutes. Using a rotary evaporator, 20 g of l-methoxy-2-propanol was added, and a procedure to remove water was repeated twice. By this, an uncoated ZnO sol (sol-5), in which the ZnO nanoparticle content in the l-methoxy-2 -propanol was 20 wt.%, was obtained.

(5) Preparation of hybrid UV absorbing agent

Various organic UV absorbing agents were mixed with any of the sol-3, the sol-4, or the sol-5 and agitated at room temperature for 1 hour to obtain hybrid UV absorbing agents. The used organic UV absorbing agents were as follows.

“TINUVIN 477”: hydroxyphenyltriazine-based UV absorbing agent; absorption maximum wavelength: 356 nm; BASF

“TINUVIN 384-2”: benzotriazole -based UV absorbing agent; absorption maximum wavelength: 345 nm; BASF

“TINUVIN 571”: benzotriazole-based UV absorbing agent; absorption maximum wavelength: 343 nm; BASF

“UVINUU 3050”: cyanoacrylate -based UV absorbing agent; absorption maximum wavelength: approximately 345 nm; BASF

(6) Preparation of coating precursor

Any of the organic UV absorbing agent, the sol-3 or the sol-5, or the hybrid UV absorbing agent and a binder (aliphatic urethane acrylate) were mixed and adjusted to make the solid content in the l-methoxy-2 -propanol 40 wt.%. Then, 0.002 g of silicone polyether acrylate (TEGO Rad 2250, Evonik) and 0.06 g of ESACURE ONE (photoinitiator, Lamberti) were added to obtain a coating precursor.

(7) Application of coating

The coating precursor was applied onto a PET substrate (A4100, Toyobo Co., Ltd.) having a thickness of 50 pm by using a Meyer rod #20 and dried in an oven at 60°C for 10 minutes. The thickness of the coating was 9 pm in the dried condition. Then, UV irradiation was performed to cure the coating to obtain a sample.

(8) Sample evaluation

The b^*, the haze, and the transmittance were measured for a coated sample. The b* was measured by using a spectrophotometer (CM-3600d, Konica Minolta, Inc.). The haze was measured by using a haze meter (NDH5000W, Nippon Denshoku Industries Co., Ltd.) in accordance with IIS K 7361-1 and IIS K 7136. The transmittance was measured by using a UV/Vis spectrophotometer (U-4100, Hitachi High-Technologies Corporation). The results are shown in Table 1 and Table 2. The light transmittance spectra of Example 3, Comparative Examples 1 and 2, and Comparative Examples 2 and 3 using TINUVIN 477, and Comparative Examples 3 to 1 using only silica-coated ZnO were shown in FIG. 1. The light transmittance spectra of Example 7, Comparative Examples 1 to 5, and Comparative Examples 2 to 6 using UVINUL 3050, and Comparative Examples 3 to 1 using only silica-coated ZnO were shown in FIG. 2. A graph showing transition of b^* in the case where an organic UV absorbing agent was used alone and in the case where uncoated ZnO or silica-coated ZnO was added to the organic UV absorbing agent was shown in FIG. 3. Table 1

Table 2

Preparation Example 2

(1) Preparation of L-lysine-modified T1O2 sol (sol-1)

0.0475 g of L-lysine (FUJIFILM Wako Pure Chemical Corporation) was added to 10 g of T1O2 sol (Resino Color Industry Co., Ltd.), 25.48 g of methanol, and 4.52 g of the mixture. After agitation was performed at room temperature for 10 minutes, the mixture was agitated for 16 hours in an oil bath at 60°C to obtain an L-lysine-modified T1O2 sol (sol-1).

(2) Preparation of silica-coated T1O2 sol (sol-2)

To the sol-1, 5.98 g of tetraethyl orthosilicate (TEOS, Wako Pure Chemical Industries, Ltd.) was added. After agitation was performed at room temperature for 10 minutes, the mixture was transferred to an autoclave and heated at 150°C for 6 hours to obtain a sol-2. Thereafter, using a rotary evaporator, water and methanol of the sol-2 were removed to adjust the solid content to approximately 20 wt.%. l-Methoxy-2-propanol was added, and a procedure to further remove the remaining water and methanol was repeated twice. By this, a silica-coated T1O2 sol (sol-3), in which the silica-coated T1O2 particle content in the l-methoxy-2 -propanol was 20 wt.%, was obtained.

(3) Preparation of uncoated T1O2 sol (sol-3)

20 g of T1O2 sol (Resino Color Industry Co., Ltd.) and 22.5 g of l-methoxy-2 -propanol were mixed at room temperature for 10 minutes. Using a rotary evaporator, 20 g of l-methoxy-2 - propanol was added, and a procedure to remove water was repeated twice. By this, an uncoated T1O2 sol (sol-3), in which the T1O2 nanoparticle content in the l-methoxy-2 -propanol was 20 wt.%, was obtained. (4) Preparation of hybrid UV absorbing agent

The organic UV absorbing agent (TINUVIN 477) was mixed with any of the sol-2 or the sol-3 and agitated at room temperature for 1 hour to obtain a hybrid UV absorbing agent. (5) Sample production and evaluation

A coated sample was produced by the same procedures as those of (6) to (8) of Preparation Example 1, and the b^*, the haze, and the transmittance were measured for the coated sample. The results are shown in Table 3. Table 3

Claims

What is claimed is:

1. A laminate comprising a substrate and a UV protection layer; the UV protection layer containing a core-shell type inorganic nanoparticle, an organic UV absorbing agent, and a binder; and the core-shell type inorganic nanoparticle having a core part containing zinc oxide or titanium oxide and a shell part containing silicon dioxide.

2. The laminate according to claim 1, wherein chromaticity b^* of Uab color system of the UV protection layer is lower than chromaticity b^* of a layer formed in the same manner except for using a nanoparticle of zinc oxide or titanium oxide in place of the core-shell type inorganic nanoparticle.

3. The laminate according to claim 1 or 2, wherein the organic UV absorbing agent contains a compound having two or more phenolic hydroxyl groups in one molecule.

4. The laminate according to any one of claims 1 to 3, wherein the core-shell type inorganic nanoparticle contains lysine, or a derivative or a decomposition product thereof at least in between the core part and the shell part.

5. The laminate according to any one of claims 1 to 4, wherein a weight ratio of the organic UV absorbing agent to the core-shell type inorganic nanoparticle in the UV protection layer is in a range from 0.01 to 0.5.

6. The laminate according to any one of claims 1 to 5, wherein a transmittance at a wavelength of 380 nm of the UV protection layer is lower than a layer formed in the same manner except for not using the core -shell type inorganic nanoparticle.

7. The laminate according to any one of claims 1 to 6, wherein a wavelength at which the transmittance of the UV protection layer is 20% is in a range from 370 nm to 400 nm.

8. The laminate according to any one of claims 1 to 7, wherein a surface of the shell part of the core-shell type inorganic nanoparticle is modified with a silane coupling agent.

9. A coating precursor for forming a UV protection coating, comprising a core-shell type inorganic nanoparticle, an organic UV absorbing agent, and a binder, and the core-shell type inorganic nanoparticle having a core part containing zinc oxide or titanium oxide and a shell part containing silicon dioxide.

10. A UV protection agent comprising a combination of a core-shell type inorganic nanoparticle and an organic UV absorbing agent; the core-shell type inorganic nanoparticle having a core part containing zinc oxide or titanium oxide and a shell part containing silicon dioxide; and the core-shell type inorganic nanoparticle containing lysine, or a derivative or a decomposition product thereof at least in between the core part and the shell part.