Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2002-01-31
2004-04-20
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S413000, C428S423100, C428S446000, C428S480000, C428S908800, C428S913300, C427S402000, C427S407100, C427S385500
Reexamination Certificate
active
06723438
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to compositions useful for providing anti-soiling properties to laminates, especially flooring and decorative surfaces.
BACKGROUND OF THE INVENTION
Laminates are gaining increasing favor as materials of construction for flooring and decorative surfaces such as counter tops. Laminates provide some resistance to soiling, abrasion and spills at a very economical cost, as compared to, for example, hardwood flooring. Typically, laminates are made from papers by impregnating the papers with resins of various kinds, assembling several resin-impregnated paper layers and consolidating the paper layers to a cured state, usually by applying heat and pressure. One or more of the paper layers can be printed with patterns for decorative purpose. Typical resins used for impregnating paper are thermoset resins such as phenolics, epoxy resins, polyesters, polyurethanes, aminoplasts such as melamine-formaldehyde resins, and the like. Laminates derived from paper impregnated with thermoset resins such as melamine-formaldehyde resins have relatively high surface energy and thus are easily subjected to soiling. Soiled laminated floors or various surfaces require frequent cleaning thoroughly with detergent. Therefore a modified laminate surface with reduced soil attraction would require much less maintenance time.
Recently, fluorochemicals have been incorporated in the overlay layers of laminates to impart added anti-soiling or easy care performance. However only a limited quantity of fluorochemicals can be employed due to phase separation and potential haze problem with the typically used melamine-formaldehyde resins. Also, fluorochemicals are fairly expensive anti-soiling agents.
There remains a need for inexpensive, effective anti-soiling agents that can be incorporated into laminates to impart improved anti-soiling properties.
SUMMARY OF THE INVENTION
The present invention provides a protective overlay, a method for forming protective overlays on substrates to protect the substrates, and decorative laminates having such overlays.
In brief summary, protective overlays of the invention comprise an at least partially cured overlay thermosettable resin and a substituted polysiloxane as described below. In brief summary, a method for forming a protective overlay on a substrate to protect the substrate comprises (a) providing a substrate having at least one surface, (b) applying to at least part of the surface an overlay thermosettable resin, (c) applying to at least part of the surface a substituted polysiloxane, wherein at least a portion of the overlay thermosettable resin and at least a portion of the polysiloxane are applied to the same part of the surface and then (d) at least partially curing the overlay thermosettable resin. In brief summary, a decorative laminate of the invention comprises (a) a decorative inner layer having at least one decorative surface and (b) an overlay layer disposed on at least a portion of the decorative surface wherein the overlay layer comprises an at least partially cured overlay thermosettable resin and a substituted polysiloxane.
According to this invention, the anti-soiling properties of laminates is improved by using substituted polysiloxane materials to coat the top protective (thermoset resin-containing) layer of a laminate or by incorporating such materials into the top protective layer of a laminate. That highly cross-linked laminate surface can be used as a protective layer due to its high resistance to abrasion and wear. Laminates of the invention can have an higher degree of anti-soil resistance and are suitable for flooring panels, table and counter tops, wall panels, kitchen cabinet, tableware, furniture and the like. The substituted polysiloxane materials used in this invention can be used at relatively high add-on levels to the resins of the laminate without imparting undesirable haze problems to the laminate.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS OF THE INVENTION
Thermosettable resins useful as overlay resins in this invention include thermosettable resins such as phenolics, epoxy resins, polyesters, polyurethanes, aminoplast resins such as melamine-formaldehyde resins, and the like. Amino resins are preferred due to performance and cost; melamine-formaldehyde resins are particularly preferred amino resins. Aqueous dispersions of thermoset resins are preferred to solutions of thermoset resins in organic solvents in order to minimize VOC emissions during curing.
A suitable amino resin is any material in the broad class of materials based on the reaction of formaldehyde with urea, melamine, benzoguanamine, or acetylguanamine. Such compounds are well known and described in, for example, “Kirk-Othmer Encyclopedia of Chemical Technology”, 3
rd
Ed. Volume 2, pages 440-469, Wiley-Interscience, 1978. Representative examples of such compounds include methylolated melamines; benzoguanamines; acetylguanamines; methylolated ureas such as dimethylolurea, dimethylolethyleneurea, tetramethylolacetylene urea, and dimethylolpropyleneurea; dimethylol derivatives of tetrahydro-5-alkyl-S-triazone; glyoxal resins such as dimethyloldihydroxyethyleneurea (DMDHEU) and tetramethylolglycoluril; methylated derivatives of any of the foregoing; and uron resins such as N,N′-bis(methoxymethyl)uron. Methylolacrylamide and methylolmethacrylamide are also included within the class of amino resins. Structures of representative amino resin moieties are shown in Table A.
TABLE A
In the Table A structures, each A′ moiety can be independently selected and can be a hydrogen atom, a hydroxymethyl group, or methoxymethyl group, each B′ moiety can be independently selected and can be a hydrogen atom, hydroxyl group, or an alkyl group, each D′ can be independently selected from the group consisting of alkyl, hydroxyalkyl, or alkoxyalkyl groups, and n is an integer from 1 to about 4. Also suitable are structures in which any or all of the hydroxymethyl or methoxymethyl groups are replaced by methylene groups. If a water soluble or water dispersible coating composition is desired, the amino resin preferably includes a plurality of hydroxymethyl groups. One such useful water dispersible amino resin is AQ 7550™ melamine-formaldehyde resin from Solutia Inc., St. Louis, Mo.
The use of urethane polyols may also be used to promote stable dispersions or solutions of otherwise water-insoluble amino resins. Useful commercially available urethanes include those sold under the K-FLEX brand by King Industries of Norwalk, Conn. Useful commercially available urethane polyols include those sold under the UD-320 and UD-350W brand by King Industries of Norwalk, Conn.
The substituted polysiloxane materials used in this invention are non-tacky solids (at room temperature) and include those with organic groups having from one to seven carbon atoms such that the substituted polysiloxanes have lower alkyls that provide an average of 0.3 to 1.5, preferably 0.5 to 1.3, carbon atoms per silicon atom.
Illustrative examples of commercially available siloxanes suitable for use in the present invention include BAYGUARD™ from Bayer Corporation, Baytown, Tex., and EPS-1926 from Kelmar Industries, Duncan, S.C.
Aqueous dispersions of lower alkyl substituted polysiloxanes of this invention can be prepared by, for instance, hydrolysis of the corresponding alkyl substituted silanes, a process well described in the literature.
In some embodiments, the substituted polysiloxane material is a polysilsesquioxane. Useful silsesquioxanes include (a) compounds having repeating units of the formula (RSiO
3/2
) where R is a substituent comprising a single alkyl or aryl group or mixtures of alkyl or aryl groups of up to 7 carbon atoms, and/or (b) condensates of hydrolsylates of the formula R
x
Si(OR′)
y
where x+y is 4 and x is from 0 to 2 and y is from 2 to 4; R is a single alkyl or aryl group or mixture of alkyl or aryl groups comprising up to 7 carbon atoms, optionally substituted with halogen atoms, mercapto groups, and/or epoxy groups; an
Chang John C.
Dunsmore Irvin F.
3M Innovative Properties Company
Dawson Robert
Feely Michael J
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