Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-03-26
2001-04-17
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S032000, C524S033000, C524S037000, C524S038000, C524S039000, C524S040000, C524S041000
Reexamination Certificate
active
06218448
ABSTRACT:
The invention pertains to viscous mixtures or pastes of a cellulose ester, a binder resin, and water, and optionally a plasticiser, an organic solvent, an emulsifier, and/or a thickener, and to coating compositions incorporating such mixtures or pastes.
BACKGROUND OF THE INVENTION
Mixtures or pastes based on cellulose esters have earlier been proposed in EP-B-076 443 and EP-B-184 127.
The products described in these documents are used to a large extent for varnishing wood, metal, synthetic material, paper, leather, glass, and plastic films, all surfaces where great value is placed on solventless coating compositions.
A drawback to the coats obtained using the known coating compositions is their poor hardness and comparatively low resistance to various liquids such as alcohol, red wine, coffee, and the like.
The invention now provides a coating composition with markedly enhanced properties such as greater hardness and improved resistance to chemicals. The invention consists in that in the mixtures or pastes of the known type mentioned in the opening paragraph wherein at least a portion of the binder resin is functionalized with an amino-functional acetal. “Amino-functional” means an amino group is present.
It should be noted that it is known in itself from EP-B-255 608 that a thermosetting coating composition can be obtained by mixing hydroxyl group-containing compounds with a non-volatile acetal-functional cross-linking agent which can be obtained by converting a compound having a free isocyanate group with a hydroxyl-functional acetal. A possible drawback to the coating compositions described in this document is that when they are applied as coats, they have to be cured at a comparatively high temperature. A further drawback is the limited availability in industrial quantities of the hydroxyacetal used in these coating compositions.
EP-A-744 449 also describes mixtures or pastes based on cellulose esters and a binder resin in coating compositions. The use of a polysiloxane compound is required to achieve enhanced stability in water, while the use of an aqueous polyisocyanate dispersion as cross-linking is necessary to obtain a coating with markedly enhanced properties.
For that reason it must be considered extremely surprising that the now proposed coating compositions can be cured in a comparatively short time even at ambient temperature. This is of major significance for industrial coating processes of heat sensitive substrates like, e.g., wood which is used in the furniture industry. The use of coatings curable only at high temperatures would not only require unacceptably high investments in that branch of industry, but also result in higher costs (e.g. energy).
SUMMARY OF THE INVENTION
The invention is, in one embodiment, a mixture comprising cellulose ester, binder resin, and water, wherein at least a portion of the binder resin is functionalized with an amino-functional acetal.
In other embodiments, the mixture further comprises a plasticizer, an organic solvent, an emulsifier and/or a thickener.
In another embodiment, the mixture is in the form of a paste.
The mixture or paste is preferably used in coating compositions.
DETAILED DESCRIPTION OF THE INVENTION
Among the cellulose esters eligible for use according to the invention are the known nitrate esters, as well as esters based on acetobutyrate and acetopropionate.
According to the invention, it was found that very favorable results can be obtained when at least a portion of the resin is functionalized by converting the amino group of the amino-functional acetal with a free isocyariate, (meth)acrylate, ester or epoxy group present in the binder resin, or with an at least difunctional compound having at least one free isocyariate, (meth)acrylate, ester or epoxy group and a group which is reactive towards one or more of the groups present in the resin to be functionalized. Usually, this means hydroxyl groups, which exhibit a high reactivity towards, e.g., isocyanate or epoxy groups.
Examples of at least difunctional isocyanate compounds include aliphatic, cycloaliphatic or aromatic di-, tri- or tetraisocyanates which may be ethylenically unsaturated or not, such as: 1,2-propylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, 2,3-butylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, 2,2,4-trimethyl hexamethylene diisocyariate, 2,4,4-trimethyl hexamethylene diisocyanate, dodecamethylene diisocyariate, &ohgr;,&ohgr;′-dipropyl ether diisocyanate, 1,3-cyclopentane diisocyanate, 1,2-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, 4-methyl-1,3-diisocyanatocyclohexane, trans-vinylidene diisocyanate, dicyclohexyl methane-4,4′-diisocyanate, 3,3′-dimethyl dicyclohexyl methane-4,4′-diisocyanate, a toluene diisocyanate, 1,3-bis(isocyanatomethyl)benzene, a xylene diisocyanate, 1,5-dimethyl-2,4-bis(isocyanatomethyl)benzene, 1,5-dimethyl-2,4-bis(2-isocyanatoethyl)-benzene, 1,3,5-triethyl-2,4-bis(isocyanatomethyl)-benzene, 4,4′-diisocyanatodiphenyl, 3,3′-dichloro4,4′-diisocyanatodiphenyl, 3,3′-diphenyl-4,4′-diisocyanatodiphenyl, 3,3′-dimethoxy-4,4′-diisocyanatodiphenyl, 4,4′-diisocyanatodiphenyl methane, 3,3′-dimethyl-4,4′-diisocyanatodiphenyl methane, a diisocyanatonaphthalene, the adduct of 2 molecules of a diisocyanate, e.g. hexamethylene diisocyanate or isophorone diisocyanate, to a diol such as ethylene glycol, the adduct of 3 molecules of hexamethylene diisocyanate to 1 molecule of water (available under the trade designation Desmodur®N of Bayer®), the adduct of 1 molecule of trimethylol propane to 3 molecules of toluene diisocyanate (available under the trade designation Desmodur®L of Bayer®), the adduct of 1 molecule of trimethylol propane to 3 molecules of isophorone diisocyanate, compounds such as 1,3,5-triisocyanatobenzene and 2,4,6-triisocyanatotoluene, and the adduct of 1 molecule of pentaerythritol to 4 molecules of toluene diisocyanate. Preferably, an aliphatic or cycloaliphatic di- or triisocyariate having about 8 to about 36 carbon atoms is employed.
Typical examples of compounds containing at least 2 acryloyl or methacryloyl groups include the (meth)acrylic esters of di-, tri- or polyvalent polyols, including polyester polyols and polyether polyols; adducts of, on the one hand, a hydroxyl group-containing (meth)acrylic ester of a polyol to, on the other hand, an at least difunctional isocyanate compound; and adducts of (meth)acrylic acid to an at least difunctional epoxy compound.
Ester compounds suitable for use are esters of polycarboxylic acids and low-boiling alcohols. Examples of these are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl esters of di-, tri- or tetracarboxylic acids such as malonic acid, adipinic acid, dimeric fatty acids, maleic acid, fumaric acid, cyclohexane-1,2-dicarboxylic acid, phthalic acid, isophthalic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, thiophene-1,5-dicarboxylic acid, trimellitic acid, ethylene tetracarboxylic acid, acetylene dicarboxylic acid, and propane-1,1,2,3-tetracarboxylic acid.
Examples of suitable at least difunctional, solid or liquid epoxy compounds include the di- or polyglycidyl ethers of (cyclo)aliphatic or aromatic hydroxy compounds such as ethylene glycol, glycerol, cyclohexane diol, mononuclear di- or polyvalent phenols, bisphenols such as Bisphenol-A and Bisphenol-F, and polynuclear phenols; glycidyl ethers of fatty acids having about 6 to about 24 carbon atoms; glycidyl(meth)acrylate; isocyanurate group-containing epoxy compounds, an epoxydised polybutadiene; hydaritoin epoxy resins; epoxy resins obtained by epoxydising aliphatic and/or cycloaliphatic alkenes, such as dipentene dioxide, dicyclopentadiene dioxide, and vinylcyclohexene dioxide, and glycidyl groups-containing resins such as polyesters or polyurethanes containing one or more glycidyl groups per molecule, or mixtures of the aforesaid epoxy resins.
So far, optimum results have been o
Heicht Reinhold
Hoppe Lutz
Kraaijevanger Paulus T. F. M.
Kruithof Klaas J. H.
Raasing Jörgen E.
Akzo Nobel N.V.
Szekely Peter
Vickrey David H.
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