Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
  • C09D175/04—Polyurethanes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2290/00—Compositions for creating anti-fogging

Definitions

• This invention relates to polymer compositions and more particularly to compositions for use in the manufacture of transparent or reflective articles.
• the surface characteristics of products formed by this process are stated to include scratch resistance. However, such coatings do not confer antimist properties to the surface.
• the invention seeks to provide a polymer composition which not only has the good antimist properties of the known hydrophilic polyurethane materials but also has good scratch and abrasion resistance and is capable of being formed into free standing structures sucn as films or sheets as well as being useful for coating substrates such as those of glass or plastic material.
• the present invention therefore provides a composition of matter naving antifog properties comprising a hydrophilic polyurethane in admixture with a compatible polymer.
• 'compatible' is meant that the polymers will co-exist with the polyurethane component without anv ohase seDaration when the oolvurethane and polymer components are admixed.
• such polyurethane polymer mixtures will exhibit good light transmitting properties.
• the compatible polymers may be homopoly ers or copolymers or mixtures of such polymers. Aptly such polymers are derived from monomers or oligomers having ethylenic unsaturation.
• composition of the invention may be formed by, for example, drying mixtures of the polyurethane - and other polymer components from a solution thereof or by polymerising the precursors for compatible polymer in the presence of the hydrophilic polyurethane component, optionally in the presence of suitable catalysts and/or polymerisation initiators.
• suitable precursors include monomers or oligomers which contain ethylenic saturation.
• a curable composition comprising a hydrophilic polyurethane and a polymerisable compound containing acrylic unsaturation.
• the polymerisable compound containing acrylic unsaturation (hereinafter called 'acrylic component') mav be oli ⁇ omeric in nature.
• the component mav contain aerylate or methacrylate groups.
• the acrylic component is a poiyfunctionai compound.
• iore aptly the acrylic component contains at least three acrylicaily unsaturated groups.
• Favoured acrylic components are poiyfunctionai ether acrylates, preferably containing at least three acrvloioxv groups. More favoured ether acrylates are penta or hexacrylates.
• Preferred acrylic components for use in the present invention are dipentaerithrytol penta- and hexacrylates pentaerithrytol triacrylate and 1,6 hexane diol - diacrylate.
• Suitable hardness and antimist properties may be achieved by the use of less than 50% by weight of the acrylic component.
• compositions of the invention contain acrylic unsaturation and are cured by cross-linking through the ethylenic bonds. Accordingly, the compositions of the invention may desiraoiy contain initiators to promote cross-linking.
• the compositions may be cured by radiation including thermal radiation, actinic, infra-red and ultra-violet radiation and electron beam.
• Favoured compositions may contain a photo-initiator reactive to U.V. light.
• Such initiators may be present in the compositions of the invention or solutions thereof in conventional amounts.
• the polyurethane component may also contain ethylenic unsaturation which may be cross-linkable.
• the polyurethane may be a urethane-acrylate block copolymer.
• Oligomeric materials which contain unsaturation and which are suitable for use in the present invention include hexafunctional aliphatic or aromatic urethane acrylates, difunctional aliphatic or aromatic urethane acrylates, epoxy Novalac acrylates, polyester tetra-acrylates and siloxane di-or hexa acrylates.
• a less preferred but still useful component is methyl methacrylate.
• the composition will comprise a mixture of a hydrophilic polyurethane and at least one other compatible polymer containing residues of a monomer having vinyl unsaturation.
• Precursors for compositions of this type may comprise a mixture of the polyurethane and the compatible polymer in a single or mixture of co-solvents.
• the compositions of the invention are formed upon drying precursor mixture and evaporatin ⁇ the solvent therefrom.
• Apt polymer materials derived from vinyl or ethylenically unsaturated precursors herein after referred to as the 'vinyl component' include vinyl chloride-vinyl acetate copolymers, hydroxy modified vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate copolymers modified with alpha-beta unsaturated carboxylic acids or epoxy compounds, polyacrvlates and methacrylates, for example polymethyl methacrylates and styrene polymers and polymer blends such as styrene-acrylonitrile and styrene-maleic acid anhydrid polymers.
• Suitable vinyl components are available under the trade name UCAR from Union Carbide.
• compositions of the present invention based on hydrophilic polyurethanes and vinyl components will contain at least 5% by weight of the total composition of vinyl component.
• the composition will contain at least 50% by weight of hydrophilic polyurethane.
• the compositions of the present invention will contain at least 10% by weight of the vinyl component and typically will contain about 15% be weight of vinyl component.
• the hydrophilic polyurethane contributes properties of water-absorption to the compositions of the invention.
• the compositions of the invention, when cured, will contain at least 30% by weight water when hydrated.
• the hydropnilic polyurethanes for use in the composition of the invention will contain at least 35% by weight water when hydrated.
• the hydrophilic polyurethane will contain at least 40% by weight when hydrated and more favourably may contain up to 60% or up to 90% water when hydrated.
• Suitable hydrophilic polyurethanes for use in the compositions of the invention include those described in US-A-4844983.
• Hydrophilic polyurethanes which may be used in the present invention will be any of those which have the water content as hereinbefore described.
• the saturation water content of the hydrophilic polyurethane will not however be such as to cause it to delaminate from a substrate.
• Favoured hydrophilic polyurethanes for use in the invention are those which are linear, that is are substantially free of cross links and which therefore are soluble in organic solvents.
• the hydrophilic polyurethanes suitable for use in the present invention may be polyether or polyester polyurethanes.
• Suitable polyesters which give rise to polyurethanes include polyesters of adipic acid such as butylene adipate.
• hydropnilic polyurethanes which are polyether polyurethanes It is particularly preferred therefore to use hydrophilic polyurethanes which are linear polyether polyurethanes.
• Apt linear polyether polyurethanes may be random polymers containing ether units derived from diolic compounds which have been reacted with dii ⁇ ocyanates.
• Suitable linear polyether polyurethanes include those described in European Patent Specification No.050035 at page 12 line 1 to page 14 line 10 and at page 32 line 7 to 33 line 12, which are incorporated herein by cross-reference and which have the required water content when hydrated.
• a linear polyether polyurethane which employs poly (ethylene glycol) derived blocks along together with a chain extender and a diisocyanate.
• the poly (ethylene glycol) may have a molecular weight of between 600 and 6000 and more suitably of between 800 and 2000.
• a particularly preferred poly (ethylene glycol) has a molecular weight of 1540.
• the chain extender will be an aliphatic diol or diamine or amineol containing up to 10 carbon atoms and most suitably up to 4 carbon atoms.
• the diisocyanate such as toluene diisocyanate, 1, 6-hexamethylene diisocyanate or
• 4 '-dicyclohexyl-methane diisocyanate A preferred diisocyanate is 4 , 4 '-dicyclohexylmethane diisocyanate.
• the ratio of hydrophilic polyurethane to acrylic vinyl component as well as the hydrophilic nature of the polyurethane will affect the physical properties of the cured composition of the invention.
• the concentration of hydrophilic polyurethane in the composition may range from 10% to 99.0% by weight of the total weight of the composition. Aptly the composition of the present invention may contain from 10 to 90% by weight of the hydrophilic polyurethane.
• composition of the invention may be cast, for example, from solution, to form self supporting sheets or film coatings.
• compositions may also contain other processing aids such as flow promoters.
• Suitable flow aids may include fully reacted materials such as silicone fluids or reactive materials such as di-and hexa-functional silicone acrylates.
• the composition of the invention may be in the form of a solution suitable for casting or moulding in which the solvents for each of the resin components are compatible with each other.
• the solvents for each of the resin components are compatible with each other.
• both the polyurethane and acrylic or vinyl components will be dissolved in a common solvent therefor.
• the solvent or solvents will be chosen to provide a solution having a viscosity suitable for- it to be cast into a sheet or formed into a film.
• Apt solvents for use in the present invention are ketones, esters and alcohols as well as mixtures thereof.
• suitable organic solvents include propyl acetate, halogenated hydrocarbons such as ethylene dichloride, alkanols such as methanol or ethanol (optionally containing small amounts of water) , ketones such as acetone or methyl ethyl ketone, methyl isobutylketone, 2-methoxyethanol 2-ethoxyethanol, diacetone alcohol or mixtures of these solvents.
• Preferred solvents are 2-ethyoxyethanol, industrial methylated spirits (IMS) or IMS together with 2 methoxyethanol in a ratio of 3:1. Normally and preferably the hydrophilic polyurethane component will be applied in its non-hydrated state.
• compositions or precursors of the invention which contain acrylic unsaturation are cured by cross-linking through the ethylenic bonds.
• the compositions of the invention may desirably contain initiators to promote cross-linking.
• the compositions may be cured by radiation including thermal radiation, actinic, infra-red and ultra-violet radiation and electron beam.
• Favoured compositions may contain a photo-iniator reactive to U.V. light. Such inhibitors may be present in the compositions of the invention or solutions thereof in conventional amounts.
• the polyurethane component may also contain ethylenic unsaturation which may be cross-linkable.
• the polyurethane may be a urethane-acrylate block copolymer.
• the compositions of the invention are dried to remove solvent prior to cross linking.
• the solids contents of solutions of compositions of the invention are chosen to provide a balance of good rheological, drying and film-forming properties.
• the solids content (polyurethane and acrylic or vinyl components) will be less than 50%, more aptly less than about 25%.
• Coatings in accordance with the invention may be prepared by conventional methods of coating surfaces such as dip coating, spraying, painting, knife-coating, on line coating or by printing.
• the composition of the invention is dissolved in a suitable organic solvent, for example having a solids content of up to 30% (by weight) or more favourably as a 5 to 15% solution for dip coating and 5 to 25% for spray coating.
• the coating is to be used in a high quality optical product, such as on a lens, it is preferred that the coating is applied as the result of dip coating.
• the solution of the polymer composition is placed in a suitable container which is raised mechanically in a controlled manner to immerse the substrate. Th.2 container is then lowered at an appropriate rate to give the desired coating thickness.
• the thickness of the coating depends upon both the solution strength, the viscosity of the solution and the rate of withdrawal of the substrate from the container. Favourably the process is carried out at between 15 and 30°C.
• the solvent is removed from the coating after withdrawal from the solution using a current of air and preferably a current of warm air at a temperature of 50 to 70°. Drying at this temperature imparts a gloss to the coating thereby presenting a better optical appearance to the coated substrate.
• the thin film of the hydrophilic polyurethane - polymer compositions of the invention may be adhered by means of a transparent adhesive which is inert to the film and the substrate.
• composition of the invention may be cast, for example, from solution, to form self supporting sheets or film coatings.
• compositions may also contain other processing aids such as flow promoters.
• compositions When cast into sheets the compositions may be used for glazing purposes such as for window panes. Alternatively, the compositions may be cast as films onto preformed substrates such as those formed from glass or plastics materials, e.g. polyacrylic or polycarbonate resins to maintain or improve light transmission or, if used as mirror, to improve or maintain reflective properties. When cast into films the compositions of the invention may be applied from solutions typically containing greater than 30% by weight solids e.g. 30-40% by weight solids.
• compositions of the present invention are light transmitting some sacrifice of the light transmitting properties compared with the base polyurethane in favour of scratch or abrasion resistance may occur when the compositions comprise an acrylic component.
• the light transmitting properties of the hydrophilic polurethane can be retained when vinyl component formations are utilised.
• Such compositions although not so scratch resistant as the urethane-acrylic components may be formulated into free-standing films for use in multilayer applications such as 'peel-off visors for helmets sucn as those for motor-cycling and sports activities without loss of optical clarity.
• composition of the present invention will greatly exceed the performance specification described in DIN 4646 part 8 (1986) for 'Lenses for eye protectors - Antifogging test'.
• Preferred compositions of the invention comprising 10% of the vinyl based resins when tested to DIN 4646/8 will transmit 80% of the original trans ittence for longer than 10 seconds.
• the present invention will be illustrated by the following example.
• the solution was sprayed onto a sheet of polymethyl methacrylate and cured under a UV lamp. A further sheet was left uncoated.
• Both sheets were then placed over a water bath containing water at 45°C. After two seconds the uncoated sheet began to mist over and was completely 'opaque' after about ten seconds. The coated sheet did not start misting over until two minutes had elapsed and then did not completely mist over. Further samples of both sheets were affixed to a mirror mounted within a shower cubicle. The shower unit was operated at maximum temperature. Inspection of the sheets showed that the uncoated sheet misted over whereas the reflective properties of the coated sheet remained intact.
• DAROCURE 1173 available from CIBA-GEIGY
• Example 3 The solution was then coated onto a sheet of perspex and passed through a drying tunnel maintained at 50°C for a period of 5 minutes and then under a UV lamp to cure the resin. After drying and curing, the coated sheet was subjected to testing according to DIN 4646 part 8. Under the test conditions fogging did not commence until 15 seconds had elapsed.
• Example 3 The solution was then coated onto a sheet of perspex and passed through a drying tunnel maintained at 50°C for a period of 5 minutes and then under a UV lamp to cure the resin. After drying and curing, the coated sheet was subjected to testing according to DIN 4646 part 8. Under the test conditions fogging did not commence until 15 seconds had elapsed. Example 3
• a 20% by weight solution was first formed by dissolving 85 parts by weight in ethoxyethanol.
• a hydroxyl modified vinyl chloride-vinyl acetate copolymer (14.9 parts by weight) was added slowly with agitation until the mixture was clear and free from striations.
• Liquid silicone acrylate (0.1 part by weight) was then added as a flow aid and the solids concentration adjusted to 15% by weight. The solution was then applied as an antimist coating to a motor cycle helmet visor.
• the coated visor was passed through a drying tunnel, maintained at 50°C for a period of 5 minutes.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Organic Chemistry (AREA)
• Macromonomer-Based Addition Polymer (AREA)
• Laminated Bodies (AREA)
• Processes Of Treating Macromolecular Substances (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

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Citations (7)

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• 1992
  • 1992-08-19 GB GB929217625A patent/GB9217625D0/en active Pending
• 1993
  • 1993-08-17 GB GB9502155A patent/GB2284821A/en not_active Withdrawn
  • 1993-08-17 WO PCT/GB1993/001744 patent/WO1994004587A1/en not_active Application Discontinuation
  • 1993-08-17 JP JP6506037A patent/JPH08500381A/ja active Pending
  • 1993-08-17 EP EP93918041A patent/EP0656022A1/de not_active Withdrawn
  • 1993-08-17 CA CA 2142373 patent/CA2142373A1/en not_active Abandoned
  • 1993-08-17 AU AU47274/93A patent/AU4727493A/en not_active Abandoned

Patent Citations (7)

Non-Patent Citations (1)

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