CN104098935A - Silicon dioxide coating for improving hydrophilcity/transmissivity - Google Patents

Abstract

The invention relates to a silicon dioxide coating for improving hydrophilcity/transmissivity, and particularly provides a product coated with the silicon dioxide coating. The product comprises a base body coated with a silicon dioxide nanometer particle layer. The silicon dioxide coating is uniform in thickness substantially, can be bonded to the base body permanently, and provides an anti-reflection and/or hydrophilic surface quality for the base body.

Description

For improving the silica dioxide coating of hydrophilicity/transmittivity

Present patent application is to be on May 16th, 2008 applying date, and what denomination of invention was the Chinese patent application 200810099062.7 of " for improving the silica dioxide coating of hydrophilicity/transmittivity " divides an application.

Technical field

The present invention relates to Nano particles of silicon dioxide coating, thereon with the goods of nanoparticle silica dioxide coating, for example Optical devices or figure media, and for the preparation of the method for such goods.

Background technology

Multiple application all needs to have can sprawl the surperficial goods of water and therefore prevent from forming water droplet on the surface of these goods.For example, the transparent plastics using in having mist or wet environment, for example the window in greenhouse, should avoid forming catoptrical water droplet, and it can reduce light transmission.Water on these materials is sprawled surface and is contributed to keep its transparency and undesirable speckle is formed to minimize.

Traffic sign for using tapetum lucidum, also needs water to sprawl character.Tapetum lucidum has the ability that a large amount of incident lights turn back to light source.Adhesion raindrop and/or dew can damage light transmission and enters tapetum lucidum and reflected by it.

The principal mode that water affects optical transmittance is to form dew.Because night when dew mainly appears at tapetum lucidum work, it is especially a problem.When the form of the water droplet with little pearl is present on traffic sign, dew can destroy incident and reflected light light path.This can make the driving person who passes by be very difficult to identify the information on this sign.On the contrary, while steadily sprawling into transparent layer on the surface of this dew at Reflecting traffic marking, the information on sign is just more easy to identify, because the thin level and smooth water layer forming can obviously not mislead very strong degree incident and reflected light path.

Water is sprawled the high complexity that top coat, the particularly problem of silicon dioxide base coating are surface chemistry, reactive chemistry and the solution chemistry of colloid silica and colloid silica film.For example, although conduct in-depth research, the interaction of ion and silica sphere can't be understood (referring to Iler, " The Chemistry of Silica completely, " John Wiley, 1979p.656).Although there is such difficulty, according to following the present invention, the silicon dioxide base water spread film that provides a kind of weather resistance to improve.

Summary of the invention

The disclosure relates to a kind of coating composition, it comprises that containing average primary particle size is 40 nanometers or the less dispersion of Nano particles of silicon dioxide and the acid of pKa<3.5, and a kind of method for coated substrates, it comprises by this coating composition coated substrates dry this coating.

The disclosure further provides a kind of coated products that comprises matrix, particularly polymer matrix, and described matrix has Nano particles of silicon dioxide coating thereon.This coating comprises Nano particles of silicon dioxide continuous coated of average primary particle size 40 nanometers or less cohesion.The thickness of this coating is uniform in fact, and durable adhesion is on this matrix.

This coating is bonding all very good to various matrixes, particularly to polymeric matrix, and can provide for such matrix outstanding average specular reflectance to reduce, and for example at least 2%.When this matrix is while being transparent, this coating can be provided as normal incidence light ratio transmission in 400～700nm wavelength region and improves by the transmissivity of the matrix of the same material of coating not.This transmission preferably improves at least 2%, and until reaches 10% or higher." transparent " used herein refers in the visible spectrum (approximately 400～700nm wavelength) of selected part, incident light transmission at least 85%.The transparency in He Jin IR district, DuiUV district also can improve.For the light of arbitrarily selected wavelength, corresponding antireflection layer also will have best thickness.

This coating can be further for matrix provides water-wetted surface, and being specially adapted to provides water-wetted surface for hydrophobic polymer matrix.This coating also can provide antifog character, and provides anti-static function for being subject to polymeric film and the sheet material of static accumulation.This coating can also be preferably polymer materials for example film and sheet material wearability is provided, improve thus its processing property.

The coating being produced by the nanoparticle compositions of these acidifyings can be further for surface for example glass and PET matrix waterproof and the durable water-wetted surface of machinery are provided, and under all temps and high humidity good antifog character.In addition, this coating can provide protective layer, and shows flushing removal organic pollutant, comprises food and machine oil, coating, dust and dirt, because the nano-pore structure of this coating tends to prevent oligomeric and infiltration polymerizable molecular.

Method of the present invention does not need solvent or the tensio-active agent for applying on matrix, and therefore harm is less, and can not increase volatile organic compounds (VOC) for air.Other advantage comprises that coating is more even, better to the weather resistance bonding better, coating of matrix, antireflective is higher and transmissivity improves, and surface easy to clean is provided in the situation that pollutent can rinse out.

Accompanying drawing explanation

Fig. 1 is the transmission electron microscope photo of the goods of preparation in embodiment 78;

Fig. 2 is the transmission electron microscope photo of the goods of comparative example 12.

Fig. 3～5th, the transmissivity figure of goods of the present invention.

Embodiment

The disclosure provides a kind of method for coated substrates, comprises with comprising pKa (H ₂o)≤3.5, preferably <2.5, be most preferably less than 1 acid peace all primary particle size be the solution coated substrates of 40 nanometers or less Nano particles of silicon dioxide, and dry this coating.

Unexpectedly, these silicon-dioxide coating compositions, when acidifying, can directly be coated in without organic solvent or tensio-active agent on hydrophobic organic and inorganic matrix.These inorganic nano-particle water dispersions hydrophobic surface for example the wetting property on polyethylene terephthalate (PET) or polycarbonate (PC) be the pH value of this dispersion and the function of this sour pKa.When being acidified to pH=2～3 with HCl, even in some embodiments until 5 o'clock, this coating composition can be coated on hydrophobic organic matrix.On the contrary, this coating composition can be rolled into a ball into pearl when neutrality or alkaline pH value on organic matrix.

Without wanting to be limited by theory, we think that the aggregate of Nano particles of silicon dioxide is by bonding in this nanoparticle surface forms by acid catalyzed siloxanes and protonated silanol group, these aggregates explained hydrophobic organic lip-deep can coating because these groups are easily adhered to enduringly by hydrophobic surface institute bonding, absorption or alternate manner.

Although described the water-containing organic solvent base coating of nanoparticle silica dispersion, it is different conventionally to there is vaporator rate in such water and the mixture of organic solvent, causes the composition of liquid phase to change continuously, and it can change the character of coating again; Cause the poor and defect of homogeneity.Although tensio-active agent can contribute to the wetting property of dispersion, it can disturb the matrix between particle and between interface bonding, often produces inhomogeneous and containing the coating of defect.

Determination of light scattering to these acidifying dispersion solutions shows, these Nano particles of silicon dioxide are easily cohesion really, the three-dimensional porous reticulated structure that (after applying and being dried) Nano particles of silicon dioxide is provided, each nanoparticle looks and firmly combines with the nanoparticle closing on therein.It is " neck connection " between adjacent silicon dioxide particle that Photomicrograph discloses this combination, its be do not have silica source for example tetraalkoxysilane under by acid, produced.Its formation ascribes strong acid in the katalysis that produces and rupture in siloxane bond.Surprisingly, in the time of in the scope of pH value 2～4, the dispersion of this acidifying presents stability.Determination of light scattering shows, the 5nm of the acidifying of these cohesions or 4nm Nano particles of silicon dioxide be during in pH=2～3 with in 10wt.% concentration, surpass one week or even over one month after still keep same size.The Nano particles of silicon dioxide dispersion of such acidifying is expected to even in the longer time, keeping stable under lower dispersion concentration.

In said composition, Nano particles of silicon dioxide used is that the Nano particles of silicon dioxide of submicron-scale is in water or the dispersion in water/ORGANIC SOLVENT MIXTURES, its average primary particle diameter is 40 nanometers or less, preferably 20 nanometers or less, more preferably 10 nanometers or less.This mean particle size can be used transmissioning electric mirror determining.This Nano particles of silicon dioxide does not preferably pass through the particle of surface modification.

Less nanoparticle, 20 nanometers or less those, when acidifying, for example tetraalkoxysilane, tensio-active agent or organic solvent just can provide better coating conventionally not need additive.In addition, this nanoparticle conventionally has and is greater than about 150m ²/ gram, be preferably greater than 200m ²/ gram, more preferably greater than 400m ²/ gram specific surface area.This particle preferably has narrow size-grade distribution, and polymolecularity is 2.0 or less, is preferably 1.5 or less.If needed, can add larger silicon dioxide granule, its content can not detract said composition on selected matrix can coating, and can not reduce transmissivity and/or wetting ability.

Inorganic silicon dioxide colloidal sol in water-bearing media is commonly known in the art, and can business obtain.Silicon dioxide gel in water or water-alcohol solution can be with trade(brand)name if LUDOX be (by E.I.duPont de Nemours and Co., Inc., Wilmington, Del.USA preparation), NYACOL (can be available from Nyacol Co., Ashland, MA) or NALCO (by Ondea Nalco Chemical Co., Oak Brook, Ill.USA preparation) business obtain.Useful silicon dioxide gel is a NALCO2326, and can be used as mean particle size is 5 nanometers, pH be 10.5 and solids content be 15wt.% silicon dioxide gel obtains.Other Nano particles of silicon dioxide can business obtaining comprise can purchased from NALCO Chemical Co. " NALCO1115 " and " NALCO1130 ", can be purchased from Remet Corp. " Remasol SP30 " and can be purchased from E.I.Du Pont de Nemours Co., " the LUDOX SM " of Inc..

Also can use water-free silicon dioxide gel (also referred to as silicon-dioxide organosol), it is silicon dioxide gel dispersion, and wherein liquid phase is organic solvent or water-containing organic solvent.In enforcement of the present invention, select silicon dioxide gel to make its liquid phase compatible with emulsion, and its liquid phase normally water or moisture organic solvent.Yet, observe stable sodium Nano particles of silicon dioxide should with organic solvent for example before alcohol dilution first by acidifying.Before acidifying, dilute and may produce poor or inhomogeneous coating.The stable Nano particles of silicon dioxide of ammonium conventionally can be with any serial dilution and acidifying.

If needed, can add larger silicon dioxide granule, its content can not reduce transmittance values and/or antifog character.These other silicon dioxide granules conventionally have and are greater than 40～100 nanometers, the preferred average primary particle size of 50～100 nanometers, and with respect to the weight that is less than the Nano particles of silicon dioxide of 40 nanometers, with the ratio of 0.2:99.8～99.8:0.2, use.Larger particle is preferably used with the ratio of 1:9～9:1.Conventionally the gross weight of silicon dioxide granule (being the summation of <40nm and larger silicon dioxide granule) in composition is 0.1～40wt.%, is preferably 1～10wt.%, most preferably is 2～7wt.%.

This coating composition comprises pKa (H ₂o)≤3.5, preferably <2.5, is most preferably less than 1 acid.Useful acid comprises organic acid and mineral acid, and the example can be oxalic acid, citric acid, H ₂sO ₃, H ₃pO ₄, CF ₃cO ₂h, HCl, HBr, HI, HBrO ₃, HNO ₃, HClO ₄, H ₂sO ₄, CH ₃sO ₃h, CF ₃sO ₃h, CF ₃cO ₂h and CH ₃sO ₂oH.Most preferred acid comprises HCl, HNO ₃, H ₂sO ₄and H ₃pO ₄.The mixture of organic acid and mineral acid need to be provided in some embodiments.In some embodiments, can use the acid that comprises pKa≤3.5 (preferably <2.5, be most preferably less than 1) and other sour acid mixture of a small amount of pKa>0.Have been found that the weak acid of pKa>4, acetic acid for example, can not provide there is required transmission, the uniform coating of cleanablity and/or weather resistance character.Especially, contain weak acid for example the coating composition of acetic acid conventionally on the surface of matrix, roll into a ball into pearl.

This coating composition comprises enough acid conventionally, to provide, is less than 5, is preferably less than 4, is most preferably less than 3 pH.In some embodiments, have been found that pH is being reduced to and is being less than after 5, can be by the pH regulator of coating composition to pH5～6.Can apply like this matrix more responsive to pH.

Four alkoxyl group coupling agents are tetraethyl orthosilicate ester (TEOS) for example, and oligomeric form alkyl polysilicates (for example poly-(diethoxy siloxanes)) for example, also can effectively improve the combination between Nano particles of silicon dioxide.The coupling agent content that coating composition comprises should limit, to prevent from destroying antireflective or the antifog character of this coating.The optimum content of coupling agent is definite in test, and it depends on characteristic, molecular weight and the specific refractory power of this coupling agent.Coupling agent, if existed, with the level of 0.1～20wt.% of Nano particles of silicon dioxide concentration, more preferably the approximately 1～15wt.% with Nano particles of silicon dioxide adds in composition conventionally.

Goods in the disclosure are the matrixes with the continuous net-shaped structure of Nano particles of silicon dioxide aggregate.This particle preferably has 40 nanometers and less average primary particle size.This mean particle size can be used transmissioning electric mirror determining.Term used herein " continuously " refers in the region applying at colloid reticulated structure almost there is no to interrupt and cover with gap the surface of matrix.Term " reticulated structure " refers to aggregate and the aggregate that is joined together to form the cancellated nanoparticle of porous three-dimensional.Term " primary particle size " refers to the mean diameter of uncongealed silicon-dioxide single particle.

Fig. 1 has shown the coated products of the present invention from embodiment 78.From it, monomer Nano particles of silicon dioxide is connected with adjacent Nano particles of silicon dioxide.This coating is uniform.On the contrary, Fig. 2 has shown the coating that contains ethanol under alkaline pH value.This coating is inhomogeneous, and monomer particle is not connected with adjacent particles.

Term " porous " refers to that this nanoparticle forms when continuous coated, the space existing between Nano particles of silicon dioxide.For single-layer coating, known to make to see through light transmission maximization and the matrix reflection minimized of optically transparent matrix in air, the specific refractory power of this coating should approach the square root of the specific refractory power that equals this matrix as far as possible, the thickness of this coating should be incident light optical wavelength 1/4th (1/4).Space in coating provides the gap of a plurality of sub-wavelengths between Nano particles of silicon dioxide, and wherein specific refractory power (RI) is changed into suddenly the specific refractory power (for example, for silicon-dioxide RI=1.44) of metal oxide particle from the specific refractory power (RI=1) of air.By regulating voidage, can produce the coating (as U.S. Patent number 4,816, shown in 333 (Lange etc.), incorporated herein by reference) of the subduplicate calculating specific refractory power with the specific refractory power that approaches very much this matrix.The coating by use with best specific refractory power, when approximating 1/4th the coat-thickness of optical wavelength of incident light, the optical transmission percentage by this coated substrate is maximized, and reflection is minimized.

Preferably, when dry, reticulated structure has approximately 25～45 volume %, the more preferably from about porosity of 30～40 volume %.In some embodiments, this porosity may be higher.Porosity can be calculated by the specific refractory power of this coating according to the method for having announced, W.L.Bragg for example, and A.B.Pippard, Acta Crystallographica, the 6th volume, the 865th page (1953), incorporated herein by reference.Use Nano particles of silicon dioxide, this porosity provides has 1.2～1.4, and the preferred coating of 1.25～1.36 specific refractory power approximates the square root of the specific refractory power of polyester, polycarbonate and polymethyl methacrylate base body.For example, the porous silicon dioxide nano particle coating that specific refractory power is 1.25～1.36 when with thickness be coated in polyethylene terephthalate matrix (RI=1.64) when upper, highly antireflecting surface can be provided.Coat-thickness can be higher, and high to several microns or mil thick, this depends on application, for example, for ease of clean remove unwanted particulate rather than antireflective.When coat-thickness improves, can predict its mechanical properties and may improve.

In some embodiments, goods of the present invention comprise matrix, it can be in fact arbitrary structures, transparent arriving is opaque, polymkeric substance, glass, pottery or metal, there is smooth, crooked or complicated shape, and form the continuous net-shaped structure of the Nano particles of silicon dioxide of aggegation thereon.When this coating is applied on transparent base when realizing optical transmittance and improve, on the range of the wavelength region between at least 400～700nm, the matrix that depends on coating, the transmissivity overall average that this coated products preferably produces normal incident light improves at least 2%, and until up to 10% or higher.Also can observe the raising of transmissivity entering under the ultraviolet of spectrum and/or the wavelength of infrared part.When 550nm measures, the preferred coatings composition being applied at least one side of light transmission matrix improves at least 5% by the percent transmission of this matrix, and preferably 10%.

Except the matrix to its coating provides antireflective, coating composition of the present invention, also for matrix provides wetting ability, is conducive to introduce antifog character.Contact on these goods directly repeating after artificial air blowing with/after these goods being remained on " steam " nozzle, if the matrix of coating is resisted the formation of little condensing drip, its density is enough to significantly reduce this coated substrate transparency, it can not fully be understood thoroughly, and thinks that so this coating is antifog.Even if form uniform water film or a small amount of large water droplet on coated substrate, but as long as the transparency of this coated substrate does not significantly reduce and makes it be difficult for understanding thoroughly, still can think that this coating composition is antifog.Under many circumstances, after this substrate contact " steam " nozzle, the moisture film that can significantly not reduce the transparency of this matrix still can retain.

In a variety of situations, if this goods produce scattering of light or dazzle or form mist and cause its fuzzy trend to reduce on this product surface, the value of these optically transparent goods will improve so.For example, protective glasses (eye-protection glasses, face shield, the helmet etc.), eyeglass, building glass window, decorative bezel, Motor vehicles window and windshield all can be to cause the mode scattered light of interference and destructive dazzle.Use such goods also can be subject to forming the harmful effect of water vapor mist on this product surface.It is desirable to, in a preferred embodiment, coated products of the present invention has outstanding antifog character, also has in addition the 550nm optical transmittance that is greater than 90% simultaneously.

This polymer matrix can comprise polymeric sheet, film or moulding material.In some embodiments, wherein need to improve transmissivity, this matrix is transparent.The transparent incident light seeing through at least 85% visible spectrum (approximately 400～700nm wavelength) that refers to of term.Transparent base can be colored or colourless.

In other embodiments, wherein need to improve wetting ability, originally this matrix can be hydrophobic.Can composition be applied on various matrixes by multiple coating method." wetting ability " used herein is only for representing this thermoplastic polymer layer's surface properties, and it is soaked by the aqueous solution, does not represent whether this layer absorbs the aqueous solution.Therefore, no matter this layer is impermeable or permeable to the aqueous solution, and thermoplastic polymer layer can be expressed as hydrophilic.The surface that the drip gauge of water or aqueous solution reveals the Static Water contact angle that is less than 50 ° thereon b referred to as " hydrophilic ".Hydrophobic matrix has 50 ° or larger water contact angle.Coating described herein can improve at least 10 ° by the wetting ability of matrix, preferably at least 20 °.

The matrix that coating composition of the present invention can apply is preferably transparent or semitransparent to visible ray.Preferred matrix is by making below: polyester (such as polyethylene terephthalate, polybutylene terephthalate), polycarbonate, poly-allyl diglycol carbonate, polyacrylic ester such as polymethylmethacrylate, polystyrene, polysulfones, polyethersulfone, homopolymerization epoxy polymer, the epoxy adduct with poly-diamines, poly-dithiol, polyethylene and ethylene copolymers, fluorinated surface, cellulose ester such as acetic ester and butyric ester, glass, pottery, organic and inorganic compounding are surperficial etc., comprise its blend and laminate.

Conventionally this matrix is the form of film, sheet, plate or the pane of material, it can be a part for goods, described goods are eyeglass, building glass window, decorative bezel, Motor vehicles window and windshield for example, and protective glasses, for example Operation mask and face screen.If optional, need, this coating can only cover a part for these goods, for example, only apply in face shield the part with eyes direct neighbor.This matrix can be smooth, bending or have shape.The goods for the treatment of coating can be by blowing, cast, extrude or prepared by injection moulding.

The goods that apply with antireflective of the present invention, antifog composition, for example disposable surgical face shield and face shield, be preferably stored in and reduce environmental exposure and antipollution independent use in packing, to prevent that antifog character from reducing.Reusable goods in used time preferably with protection with seal the package combination that this product can not be exposed to environment completely and use.For forming the material of this packing, should be formed by nonpollution material.Have been found that some material can cause the partially or completely forfeiture of antifog character.Although without any theory restriction, once think that at present the material that comprises softening agent, catalyzer and other aging low molecular weight substance that can volatilization can be absorbed in coating and cause the reduction of antifog character.

Therefore, the invention provides protective glasses, for example Operation mask and face screen, and eyeglass, window and the windshield with antireflective and antifog character.

In other embodiments, this matrix must not be transparent.Have been found that said composition is for matrix is for example for drawing and the fexible film of label provides the surface of easy cleaning.Fexible film can by polyester for example PET or polyolefine for example PP (polypropylene) make, PE (polyethylene) and PVC (polyvinyl chloride)) be particularly preferred.Can use conventional film technique, for example, by matrix resin film extrusion and optional film single shaft or the diaxial orientation that this is extruded, matrix be formed to film.Use for example chemical treatment, corona treatment for example air or nitrogen corona, plasma body, flame or actinic radiation, can process this matrix to improve the binding property between matrix and hard coat.If needed, also can between matrix and coating composition, apply optional articulamentum to improve interlaminar adhesion.Also can use the opposite side of above-mentioned disposal methods matrix, to improve the binding property between matrix and tackiness agent.As known in the art, this matrix can be with pattern, for example word or symbol.

In some embodiments, this coating composition provides improved cleanablity and solid wearing layer is provided, and protection matrix and figure below show the infringement that not caused by reasons such as cut, wearing and tearing and solvent." can clean " and refer to that coating composition, after solidifying, provides oil resistant and resistance to soiling, to help this coated products not to be exposed to for example pollution of oily or external dirt of pollutent.If easy cleaning more when this coating composition also can make this hard coat be made dirty therefore only need to simply rinse with removal pollutent in water.

For said composition being evenly coated to from aqueous system on hydrophobic matrix, the surface tension that the surface of increase matrix can and/or reduce coating composition can be to be applicable to.By used corona discharge or flame-treating process oxidation base surface before applying, can carry high surface energy.These methods can also be improved the bonding of this coating and matrix.Other method that can improve the surface energy of goods comprises use undercoat, for example polyvinylidene dichloride (the shallow layer of PVDC.Or, can be by adding lower alcohol (C ₁～C ₈) reduce the surface tension of coating composition.Yet in some cases, for the uniform coating that required character is improved this coating hydrophilic and obtained by the aqueous solution or water-alcohol solution in order to ensure goods, adding wetting agent may be useful, it is tensio-active agent normally.

Term used herein " tensio-active agent " refers to the molecule that comprises hydrophilic (polarity) and hydrophobic (nonpolar) region in same a part, and it can reduce the surface tension of coating solution.Useful tensio-active agent can comprise US6, and 040,053 (Scholz etc.) those disclosed, by reference to introducing herein.

For example, for the common concentration of Nano particles of silicon dioxide (being about 0.2～15wt.% with respect to total coating composition), most of surfactant content are less than the approximately 0.1wt.% of this coating composition, preferred approximately 0.003～0.05wt.%, to keep its antireflective properties of this coating.Should be understood that for some tensio-active agents, surpassing under the concentration that realizes antifog character needs, can obtain spotty coating.

When adding in order to improve the homogeneity of formed coating, the anion surfactant in coating composition is preferred.Useful anion surfactant includes but not limited to have those that comprise following molecular structure: (1) at least one hydrophobic part, for example about C ₆～about C ₂₀alkyl, alkaryl and/or thiazolinyl, (2) at least one anionic group, such as sulfate radical, sulfonate radical, phosphate radical, polyoxyethylene sulfate radical, polyoxyethylene sulfonate radical, polyoxyethylene phosphate radical etc., and/or the salt of (3) such anionic group, wherein said salt comprises an alkali metal salt, ammonium salt, tertiary amide etc.The representative goodss example of useful anion surfactant comprises Sodium Lauryl Sulphate BP/USP, with commodity TEXAPON L-100 available from Henkel Inc., Wilmington, Del., or with commodity POLYSTEP B-3 available from Stepan Chemical Co., Northfield, Ill.; Bay ether sodium sulfate, with commodity POLYSTEP B-12 available from Stepan Chemical Co., Northfield, Ill.; Texapon Special, with commodity STANDAPOL A available from Henkel Inc., Wilmington, Del.; And Sodium dodecylbenzene sulfonate, with commodity SIPONATE DS-10 available from Rhone-Poulenc, Inc., Cranberry, N.J..

At coating composition, do not comprise tensio-active agent or in the situation that needs improve coating uniformity, it may be useful adding another kind of wetting agent, comprise those that can not give durable antifog character, to guarantee the uniform coating from water or water-alcohol solution of these goods.The example of useful wetting agent comprise polyethoxylated alkyl alcohol (for example can be from ICI Americas, " the Brjj that Inc business obtains ^tM30 " and " Brjj ^tM35 ", and " the Tergitol that can obtain from Union Carbide Chemical and Plastics Co. business ^tMtMN-6 ^tMspecialty Surfactant "), polyethoxylated alkylphenol is (for example, from " the Triton of Union Carbide Chemicals and Plastics Co. ^tMx-100 " and from " the Iconol of BASF Corp. ^tMnP-70 ") and polyethylene/polypropylene glycol segmented copolymer (can be used as " Testronic ^tM1502 block copolymer surfactants ", " Testronic ^tM908 block copolymer surfactants " and " Pluronic ^tMf38 block copolymer surfactant " business is available from BASF, Corp.).Certainly, the wetting agent of any interpolation must comprise and can not damage the antireflective of coating and the level of antifog character.Conventionally the consumption of wetting agent is less than the approximately 0.1wt.% of coating composition, preferably according to the content of Nano particles of silicon dioxide, at approximately between 0.003～0.05wt.% of coating composition.This coated products can be rinsed in water or soak and remove excessive tensio-active agent or wetting agent.

Said composition is preferably used routine techniques to be coated on goods, for example excellent painting, roller coat, curtain painting, rotogravure coating, spraying or dip-coating technology.Preferred mode comprises that rod is coated with and roller coat, or air knife is coated with regulating thickness.In order to ensure the even coating of film and wetting, can before applying, use corona discharge or flame-treating process oxidation base surface.Other method that can improve product surface energy comprises use undercoat, for example polyvinylidene dichloride (PVDC).

Coating of the present invention preferably applies with uniform mean thickness, and its variation is less than approximately , be more preferably less than , to avoid visible interference color in coating to change.The suitableeest average dry coating thickness depends on concrete coating composition, but according to use elliptic polarization spectrometer for example Gaertner Scientific Corp Model No.L115C measure, the mean thickness of this coating is conventionally , preferably , more preferably .On this scope and under, its antireflective properties of this coating can obviously weaken.Yet although it should be pointed out that average coat-thickness is preferably uniform, the specified point of actual coat-thickness this coating can noticeable change to another.The variation of this thickness, when the region with vision sensitivity is associated, the wide band antireflective character to coating, is actually useful.

Coating of the present invention is preferably coated on the two sides of matrix.Or coating of the present invention can be coated in the one side of matrix.The opposing face of this matrix can not apply, or with conventional surfactants or the antifog composition of polymerization U.S. Patent number 2 for example, 803, 552, 3, 075, 228, 3, 819, 522, 4, 467, 073 or 4, 944, disclosed those (all by reference to introducing herein) coatings in 294, or with antireflective composition U.S. Patent number 4 for example, 816, in 333, disclosed antireflective composition or J.D.Masso are at " Evaluation of Scratch Resistant and Anti-reflective Coatings for Plastic Lenses, " laminated coating described in (the same) applies, both by reference to introducing herein.Preferably, this antifogging coating surface should be towards the direction of higher levels of humidity, and the one side for example on face shield with antifogging coating should be towards wearer.Opposing face can have transparent elastic and/or tough and tensile coating is worn and torn with antagonism particle, and/or wind is cracked.

Once coating, goods are conventionally dry in circulation stove at the temperature of 20～150 ℃.Can circulated inert gas.Can further improve temperature to accelerate drying process, but must be in addition carefully to avoid the infringement to matrix.Coating composition is being applied on matrix and after dry, this coating preferably comprises the about Nano particles of silicon dioxide of 60～95wt.% (more preferably from about 70～92wt.%) (being generally cohesion), the approximately tensio-active agent of the tetraalkoxysilane of 0.1～20wt.% (more preferably from about 10～25wt.%) and optional approximately 0～5wt.% (more preferably from about 0.5～2wt.%), and the wetting agent of maximum about 5wt.% (preferably 0.1～2wt.%).

When coating composition of the present invention being applied on matrix so that its antireflective properties to be provided, by improving the optical transmittance of this coated substrate, reduced dazzle.Preferably, when the matrix phase with coating not than time, this coated substrate shows at 550mm place (for example, at the peak response of this wavelength place human eye display light-vision), normal incidence optical transmittance is increased to few 3 percentage points and nearly 10 percentage points or higher.Percentage transmission depends on input angle and light wavelength, uses the ASTM testing method D1003-92 that is entitled as " Haze and Luminous Transmittance of Transparent Plastics " to determine, it is by reference to introducing herein.Preferably, use 550nm light, when the matrix with coating is not relatively time, this coated substrate shows percentage transmission and improves and be greater than 3%, more preferably greater than 5%, is most preferably greater than 8%.When required purposes relates to significantly " from axle " (being nonnormal incidence), watch or undesirable reflex time, particularly, in the situation that reflection approaches or surpasses the object brightness in observation, can obtain larger visuality.

Coating composition of the present invention as discussed above provides antifog and its antireflective properties for the surface with its coating.The proneness of resisting the water droplet that forms the transparency that easily obviously reduces this coated substrate by coating, has proved antifog character.Water vapor from for example human body respiration easily condenses on coated substrate with the form of thin uniform water film, rather than as water droplet.This uniform films can significantly not reduce sharpness or the transparency of matrix.

In a lot of embodiments, coating composition of the present invention is all resistance to storage, and for example it can gel, becomes opaque, or significantly deteriorated.In addition, in a lot of embodiments, use testing method described herein, coated products is durable with anti abrasive.

embodiment

material

Nano particles of silicon dioxide dispersion is Nalco1115 ^tM(4nm), 2326 ^tM(5nm), 1030 ^tM(13nm), 1050 ^tM(20nm), 2327 ^tM(20nm), 45nm and 93nm, available from Nalco Company, Naperville, IL.

Tetraethoxysilane (TEOS, 99.9%) is available from Alfa Aesar, Ward Hill, MA.

Polyethylene terephthalate (PET) film is available from E.I.DuPont de Nemours, Wilmington, and DE, trade(brand)name " Melinex618 ", has the thickness of 5.0 mils and the surface of primary coat.

Polycarbonate (PC) film with commodity LEXAN8010 (0.381-mm), 8010SHC (1.0-mm) and QQ92 available from GE Advanced Materials Specialty Film and Sheet, Pittsfield, MA.

Bynel-3101 ^tMpolyethylene and ethylene copolymers, available from E.I.DuPont de Nemours & Co., Wilmington, Del.

Pellathene2363 ^tMpolyether based polyurethanes, available from Dow Chemical, Midland, MI.

Polyvinyl chloride (PVC) film is 3M (TM) Scotchcal ^tMluster Overlaminate8519,1.25 mils, available from 3M Company, St.Paul, MN.

PC (embodiment 84) with PFPE coating refers to the polycarbonate matrix with PFPE coating thereon, according to 11/828566 (Klun etc., embodiment 1 preparation by reference to introducing herein), use comprises 0.5wt.% and is coated with as face by the solution of preparing the SHC-1200 of 2 PFPE that obtain.

Sample preparation:

With deionized water, Nano particles of silicon dioxide dispersion (size shown in embodiment) is diluted to 5wt.%, with dense HCL acidified aqueous solution to described pH value (being generally 2-3).For some embodiment, with TEOS or organic solvent, with the ratio described in table, mix mutually with the Nano particles of silicon dioxide dispersion (5wt.%) of this acidifying.

Use continuous coating machine (blocked coater) or Meyer rod, with 1 mil gap and 5wt.% silica dispersion (total silica weight), apply described matrix,, the dry coating of thickness within the scope of 100～200nm is provided.By this coated sample be heated to 80～100 ℃ 5 minutes～10 minutes, dry to realize.

Transmissivity

Use Varian Cary5E spectrophotometer, under 20% relative humidity, carry out transmission and reflection measurement.Use range is the Nanoscope IIIa of 500nm～5um, and Dimension5000AFM microscope (Digital Instruments, Santa Barbara) is collected atomic force microscope (AFM) highly picture and phase place picture.PET or coating on glass are carried out to multi-angle elliptic polarization spectrometer (M2000) measurement.At the input angle place of 70 °, carry out the measurement of 300～900nm.Within the scope of this, measure film thickness, at 555nm place, measure refractive index value.

Contact angle is measured

Use and pass through available from Millipore Corporation (Billerica, MA) the former state deionized water that filtration system filters, deriving from AST Products (Billerica, MA), on the video contact angle analyser of production code member VCA-2500XE, dry coating sample is carried out to the measurement of Static Water contact angle.The numerical value of report is the average value measured of at least three drops measuring on the right side of drop and left side, is shown in table.For static measurement, droplet size is 1 μ L.

Antifog test

The instant appearance of the coated side of blowing by the breathing to towards nonalcoholic evaluator changes to assess antifog character.Antifog character grading is as follows:

5=is outstanding

4=is good

3=is poor

Durability test

By as shown in embodiment, with dry and wet Kimwipe ^tMthe paper handkerchief wiping coatingsurface of exerting oneself is assessed mechanical endurance.The numeric representation of reporting in form is the required wiping number of times of decoating visibly.Make to determine with light transmission whether coating retains or remove.

Easy cleaning test

Dirty diesel oil, vegetables oil or soap are applied to coatingsurface the preceding paragraph time (2 minutes to spending the night).Then, Polluted area is carried out to water flushing until dirty oil or vegetables oil are removed completely.When the flow velocity of application is set as 750mL/min, the time that record consumes.Conventionally, this washing time is in 1 minute.Then repeat 4～5 clean cycle.By cleaning speed (time) and irreducible oil from the teeth outwards, assess cleanablity.By the use Kimwipe that wets ^tMpaper handkerchief this coatingsurface of wiping of exerting oneself is evaluated the mechanical endurance on surface easy to clean.

In following comparative example and embodiment 1-5, with shown in 5wt.% nanoparticle silicon dioxide compositions at the coat-thickness of pH2～3 and 1 mil (～25 microns), apply polyethylene terephthalate (PET) matrix through corona treatment, 80～100 ℃ dry 5～10 minutes.Mechanical endurance and the transmissivity of using aforementioned testing method to test this coating sample improve.The results are shown in table 1.For comparison purposes, also tested the sample that uses 93nm silicon-dioxide.From test result, sum up: less granularity shows the weather resistance of raising.

Table 1

In following examples 6～8, apply as previously mentioned and test undressed polyethylene terephthalate matrix.On this matrix, be difficult for to apply 45nm or the moisture acidifying dispersion of volume particle size more.

Table 2

In following examples 9～20, with shown in 5wt.% nanoparticle silicon dioxide compositions under the coat-thickness of pH2～3 and 1 mil (～25 microns), coating, through the polyethylene terephthalate matrix of corona treatment, is dried 5～10 minutes at 110～120 ℃.The tetraethoxysilane (TEOS) of ratio shown in some embodiment further comprise.Test as previously mentioned this coating sample.From test result, sum up: add the weather resistance that tetraethoxysilane has improved this coating.

Table 3

In following examples 21～28, with shown in 5wt.% mix nanoparticles silicon dioxide compositions, under the coat-thickness of pH2～3 and 1 mil (～25 microns), apply the polyethylene terephthalate matrix through corona treatment, at 110～120 ℃, be dried 5～10 minutes.The tetraethoxysilane (TEOS) of ratio shown in some embodiment further comprise.Test as previously mentioned this coating sample.From test result, sum up: TEOS has improved the weather resistance of stuff and other stuff system.

Table 4

In following examples 29～32, with shown in 5wt.% nanoparticle silicon dioxide compositions, under the coat-thickness of pH2～3 and 1 mil (～25 microns), apply undressed polyethylene terephthalate matrix, at 110～120 ℃, be dried 5～10 minutes.The tetraethoxysilane (TEOS) of ratio shown in said composition further comprises.Test as previously mentioned this coating sample.From test knot, sum up: tetraethoxysilane has improved the weather resistance of coating on undressed PET.

Table 5

In following examples 33～40, with shown in 5wt.% mix nanoparticles silicon dioxide compositions (containing the mixture of different size), under the coat-thickness of pH2～3 and 1 mil (～25 microns), apply undressed polyethylene terephthalate matrix, at 80～100 ℃, be dried 5～10 minutes.The tetraethoxysilane (TEOS) of ratio shown in said composition further comprises.Test as previously mentioned this coating sample.From test result, sum up: tetraethoxysilane has improved the coating weather resistance of stuff and other stuff composition on undressed PET.

Table 6

In following examples 41～42, with shown in 5wt.% mix nanoparticles silicon dioxide compositions, under the coat-thickness of pH2～3 and 1 mil (～25 microns), apply undressed polyethylene terephthalate matrix, at 80～100 ℃, be dried 5～10 minutes.This embodiment has contrasted the performance of water dispersion and alcoholic dispersion.Only by wet Kimwipe test mechanical weather resistance.When ethanol is during without acidifying, this comparative example has shown poor performance.

Table 7

In the following Examples and Comparative Examples, studied the pH dependency of coating performance.In comparative example, nanoparticle applies as alkaline dispersion.Then by coating performance with wherein the dispersion of pH regulator to 2～3 is compared, the dispersion that was then again adjusted to pH5～6 with the pH value of this acid dispersion wherein before coating is compared.As shown in table 8, each dispersion has 5wt.% nanoparticle.This matrix is undressed PET.To provide the dispersion called after of vision uniform coating " can apply ".Roll into a ball into pearl and/or the coating called after " beading up " of the inhomogeneous coating of vision is provided.The embodiment of the nano particle emulsion with assorted size is also provided.These embodiment confirmed acidifying on can coating and through regulate again pH keep can coating impact.

Table 8

Embodiment	SiO 2Nanoparticle dispersion	Initial pH	Acidifying pH	Regulate again pH	Coating property
						Comparative example 3	4nm nanoparticle	10	n/a	n/a	Beading up
43	4nm	10	1-3	n/a	Can apply
						44	4nm	10	1-3	5-6	Can apply
Comparative example 4	5nm	10	/	/	Beading up
						45	5nm	10	1-3	n/a	Can apply
46	5nm	10	1-3	5-6	Can apply
						Comparative example 5	20nm	10	n/a	n/a	Beading up
47	20nm	10	1-3	n/a	Can apply
						48	20nm	10	1-3	5-6	Can apply
Comparative example 6	45nm	10	n/a	n/a	Beading up
						49	45nm	10	1-3	n/a	Beading up
50	The 4nm/45nm of 1:1	10	1-3	n/a	Can apply
						51	The 4nm/45nm of 1:9	10	1-3	n/a	Can apply
52	The 5nm/45nm of 1:1	10	1-3	n/a	Can apply
						53	The 5nm/45nm of 1:9	10	1-3	n/a	Can apply
54	The 4nm/93nm of 1:1	10	1-3	n/a	Can apply
						55	The 4nm/93nm of 1:9	10	1-3	n/a	Can apply
56	The 5nm/93nm of 1:1	10	1-3	n/a	Can apply
						57	The 5nm/93nm of 1:9	10	1-3	n/a	Can apply

In embodiment 58～63 and comparative example 7～8, with shown in 5wt.% nanoparticle silicon dioxide compositions, shown in the coat-thickness of pH, 1 mil (～25 microns) under, apply undressed polyethylene terephthalate matrix, 110～120 ℃ dry 5～10 minutes.Embodiment 59,60,62 and 63 silicon-dioxide with 98:2: the ratio of tensio-active agent, comprises Rhone-Poulenc, the tensio-active agent SIPONATE of Inc. ^tMdS-10.Static Water contact angle, transmissivity and anti-fog performance have been reported.These embodiment have shown that pH is on can coating and the impact on coating performance.

Table 9

In following examples 64～82 and comparative example 9～14, with shown in 5wt.% nanoparticle silicon dioxide compositions, shown in the coat-thickness of pH, 1 mil (～25 microns) under, apply undressed polyethylene terephthalate matrix, at 110～120 ℃, be dried 5～10 minutes.Reported the water contact angle that moves forward and backward.In embodiment 84, matrix is the polycarbonate with PFPE coating, according to embodiment 1 preparation of 11/828566 (Klum etc., by reference to introducing herein), the solution of the SHC-1200 of the PFPE that the preparation 2 that use comprises 0.5wt.% obtains is coated with as face.In embodiment 85, this matrix is with commodity Bynel ^tMthe anhydride modified polyethylene polymer of selling, can be purchased from E.I.DuPont de Nemours & Co., Wilmington, Del..Stably expressed did not have gel at least 2 months.These embodiment confirm, dispersion stability is with can coating relevant with pH and granularity.

Table 10

In following examples 86～89, with shown in 5wt.% nanoparticle silicon dioxide compositions, under the coat-thickness of pH2～3,1 mil (～25 microns), apply undressed polyethylene terephthalate matrix, at 110～120 ℃, be dried 5～10 minutes.Measure initial transmission, then make 100 wipings " wet rubbing " that this sample is subject to hygenic towelette to measure weather resistance, again measure transmissivity.Also tested in addition antifog character.In embodiment 87 and 89, added DS-10 tensio-active agent.Further by assess antifog property over aging at least 11 days under 50 ℃ and 95% humidity.Embodiment display surface promoting agent does not significantly damage and has improved anti-fog performance to coating performance.

Table 11

In following examples 90～93 and comparative example 15～16, with shown in 5wt.% nanoparticle silicon dioxide compositions, shown in pH value and the coat-thickness of 1 mil (～25 nanometer) under, apply ceramic tile, at 110～120 ℃, be dried 5～10 minutes.By immersing in soap foam (soap scum) and then successfully rinsing out soap foam with current to carry out the flushing that soap foam easily removes clean.By with hygenic towelette or alternately evaluate coating weather resistance with dry paper handkerchief wiping; With the transmission of measurement light, measuring this coating is retain or removed.If strong and inhomogeneous if there is pin hole or interference color, coating quality is poor.

Table 12

In following examples 94 and comparative example 17, with shown in 5wt.% nanoparticle silicon dioxide compositions, shown in the coat-thickness of pH, 1 mil (～25 microns) under, apply undressed polyphenyl dioctyl phthalate glycol ester matrix, 110～120 ℃ dry 5～10 minutes.By several oil droplets being applied on this coating sample and then successfully rinsing out with the narrow current of 750mL/min the flushing that oil droplet carries out easy oil removing, clean.By with hygenic towelette or alternately evaluate coating weather resistance with dry paper handkerchief wiping; With the transmission of measurement light, measuring this coating is retain or remove.

Table 13

In Fig. 3～5, tested the transmissivity of this coated products.These goods, mainly according to described in embodiment 1, are used the preparation of polyethylene terephthalate (PET) film matrix.

In Fig. 3, sample is as follows:

A polyethylene terephthalate (PET) film, in contrast

B pH is the 5wt.% water dispersion of 2 5nm silicon-dioxide

C pH is the 5wt.% alcoholic dispersion of 2 5nm silicon-dioxide

D pH is the 5wt.% alcoholic dispersion of 10 5nm silicon-dioxide

As shown in Figure 3, sample B and C compare with the PET sample A of coating not, show much higher transmissivity.Under alkaline pH value, the sample D of coating does not show sample B and any raising in 350～600 nanometer wave strong points of C.

In Fig. 4, sample is as follows:

A polyethylene terephthalate (PET) film, in contrast

E pH is the 5wt.% water dispersion of 2 5nm/45nm mixture (10:90)

F pH is the 5wt.% alcoholic dispersion of 2 5nm/45nm mixture (10:90)

G pH is the 5wt.% water dispersion of 2 5nm/90nm mixture (10:90)

H pH is the 5wt.% alcoholic dispersion of 2 5nm/90nm mixture (10:90)

I pH is the 5wt.% alcoholic dispersion of 10 5nm/90nm mixture (10:90)

J pH is the 5wt.% alcoholic dispersion of 2 90nm

K pH is the 5wt.% alcoholic dispersion of 10 90nm

L pH is the 5wt.% alcoholic dispersion of 2 45nm

In Fig. 5, sample is as follows:

A polyethylene terephthalate (PET) film, in contrast

M pH is the 5wt.% water dispersion of 2 4nm/45nm mixture (50/50 weight ratio), and one side applies

N pH is the 5wt.% water dispersion of 2 4nm, and one side applies

O pH is the 5wt.% water dispersion of 2 4nm/45nm mixture (50/50 weight ratio), dual coating

P pH is the 5wt.% water dispersion of 2 4nm, dual coating

Contrast by sample M and O or N and P can be found out, by this base film of dual coating, can greatly improve the transmissivity of this matrix.

Claims (20)

1. a method for coating is provided for matrix, and the method comprises makes matrix contact with coating composition, and described coating composition comprises:

A) water of 0.5～99wt.%;

B) median size of 0.1～20wt.% is 40nm or less Nano particles of silicon dioxide;

C) median size of 0～20wt.% is 50nm or larger Nano particles of silicon dioxide, wherein b) and summation c) be 0.1～20wt.%;

D) content is enough to pH to be reduced to the mineral acid of the pKa<3.5 that is less than 5;

E) with respect to the amount of Nano particles of silicon dioxide, the tetraalkoxysilane of 0.1～20wt.%,

And dry so that Nano particles of silicon dioxide coating to be provided.

2. method according to claim 1, the concentration of wherein said Nano particles of silicon dioxide in coating composition is 0.1～20wt.%.

3. method according to claim 1, wherein said matrix is the hydrophobic matrix that Static Water contact angle is greater than 50 °.

4. method according to claim 1, the water dispersion of wherein said Nano particles of silicon dioxide also comprises the Nano particles of silicon dioxide that median size is greater than 40 nanometers.

5. method according to claim 1, wherein said acid is selected from H ₃pO ₄, HCl, HBr, HI, HBrO ₃, HNO ₃, HClO ₄, H ₂sO ₄, CH ₃sO ₃h, CF ₃sO ₃h, CF ₃cO ₂h and CH ₃sO ₂oH.

6. a hydrophilic article of being prepared by method claimed in claim 1.

7. method according to claim 1, wherein said Nano particles of silicon dioxide has 20 nanometers or less median size.

8. method according to claim 1, wherein said Nano particles of silicon dioxide has 10 nanometers or less median size.

9. method according to claim 1, wherein said matrix has the Static Water contact angle that is less than 50 ° after coating.

10. method according to claim 1, the pH of wherein said coating composition is less than 3.

11. methods according to claim 1, comprise the following steps: add enough acid with by the pH regulator of described coating composition to being less than 5, then add enough alkali with by the scope of pH regulator to 5～6.

12. 1 kinds of coated goods, comprise the coating that method claimed in claim 1 obtains of passing through on matrix and its, described coating is that median size is the aggregate of 40 nanometers or less Nano particles of silicon dioxide, described aggregate comprises the three-dimensional porous reticulated structure of Nano particles of silicon dioxide, and described Nano particles of silicon dioxide is combined with adjacent Nano particles of silicon dioxide.

13. coated goods according to claim 12, have the water contact angle that is less than 50 °.

14. coated goods according to claim 12, the thickness of wherein said coating is

15. coated goods according to claim 12, wherein said matrix is transparent.

16. coated goods according to claim 15, wherein, with not coated matrix phase ratio, the normal incidence optical transmission in 400～700nm wavelength region is improved.

17. coated goods according to claim 16, wherein said average transmittance has improved at least 2%.

18. coated goods according to claim 12, the specific refractory power of wherein said coating is between 1.2～1.4 specific refractory power.

19. coated goods according to claim 12, wherein said coating comprises:

The Nano particles of silicon dioxide of the cohesion of a.60～95wt.%,

B.0.1 the tetraalkoxysilane of～20wt.%,

C. the tensio-active agent of 0～5wt.% alternatively, and

D.0 the wetting agent of～5wt.%.

20. 1 kinds of coating compositions, comprise:

A) water of 0.5～99wt.%,

B) median size of 0.1～20wt.% is 40nm or less Nano particles of silicon dioxide,

C) median size of 0～20wt.% is greater than the Nano particles of silicon dioxide of 50nm, wherein b) and summation c) be 0.1～20wt.%;

D) content is enough to pH to be reduced to the mineral acid of the pKa<3.5 that is less than 5;

E) with respect to the amount of Nano particles of silicon dioxide, the tetraalkoxysilane of 0.1～20wt.%.