Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1998-08-20
2001-04-03
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S530000, C525S532000, C008S115520, C008S115530, C008S115620, C008S636000, C008SDIG001, C442S154000, C442S156000, C442S168000, C442S170000, C442S164000, C526S075000, C526S321000, C522S078000, C522S103000, C427S513000
Reexamination Certificate
active
06211308
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for coating or printing on a textile by applying thereto a water-free, energy-curable, polymer-forming composition, especially useful as or in a coating or ink, the composition containing an epoxy oligomer, and an alkoxylated polyol monomer.
2. Background of the Art
Printing inks generally are composed of coloring matter such as pigment or dye dispersed or dissolved in a vehicle. The ink can be a fluid or paste that can be printed onto a substrate such as paper, plastic, metal, or ceramic and then dried.
Inks can be classified according to the substrate onto which the ink is intended to be applied or the method of application. For example, inks can be applied by raised type (e.g. letter press, flexographic), from a planar surface (lithographic), from a recessed surface (intaglio) or through a stencil (silk screen). Different methods of application and different substrates require different properties in the ink.
In silk screen printing, the ink is forced onto a substrate through a stencil, or “mask”, having a porous screen area configured in the shape of the indicia to be printed such as letters or graphics. The substrate can be paper, textile, metal, ceramic, polymer film, and the like. The screen can be a gauze or mesh fabricated from metal, silk, or various polymer materials.
The mask is generally prepared by coating a screen with a curable composition, curing the composition, and then engraving indicia on the screen. The engraved areas are porous, thereby permitting ink to be forced through the screen onto the substrate to print the indicia.
After printing, the ink on the substrate is cured or hardened by any of several methods such as, for example, exposure of the ink to heat or radiation (e.g. ultraviolet, electron beam, and the like), evaporation of a solvent in the ink composition, or oxidation hardening of drying oil components (e.g linseed oil, tung oil), and the like.
Apart from printing, coatings can also be applied to substrates for purposes of surface modification. For example, coatings can be applied to textiles to improve color fastness, water repellency, or other properties.
The three main technologies being practiced today which make up the bulk of the coatings and inks include solvent borne, water borne, and zero volatile organic compounds (VOC). Solvent borne and water borne systems produce inks and coatings which, in their uncured state, are washable. Water washability is a desired feature of the coating composition since the coating application equipment needs to be cleaned for reuse. However, there has been a technological push to eliminate organic solvents and water as components in the ink or coating composition. Organic solvents present environmental health concerns. And both solvent based and water based systems are energy intensive, requiring drying ovens to remove the solvent or water. For example, thermally induced drying and curing of coated screen fabric typically requires about 7,000 to 12,000 kilojoules of energy per kilogram of fabric as well as a long curing time, typically several hours.
The use of textiles as a substrate for printing and coating presents additional problems. For the past two decades considerable efforts have been made to develop energy polymerizable screen printing inks for fabrics. One desired property of an ink or coating applied to textiles is that the ink or coating adheres firmly to the textile. For example, a poorly adherent ink will not have the requisite color fastness or abrasion resistance and may degrade under normal wearing and washing conditions. A high degree of crosslinking enhances abrasion resistance and color fastness, and facilitates the grafting of the ink onto the fabric. However, another desired property is that the ink or coating be flexible. With a stiff ink or coating the textile loses the tactile properties, or “feel,” of the original fabric. Low crosslinking produces soft, flexible films. Consequently, what is desired is a method for printing or coating a textile with a waterless, zero VOC composition wherein the treated textile retains its original feel while exhibiting good color fastness and durability of the ink or coating.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method for coating a textile is provided herein which comprises:
a) providing a substantially water-free, energy-curable, polymer-forming composition containing
i. an acrylate oligomer having at least two ethylenically unsaturated moieties, and
ii. at least one alkoxylated polyol monomer having at least two ethylenically unsaturated moieties and capable of being copolymerized with epoxy oligomer (a) to provide a solid cured polymer when exposed to energy-polymerizing conditions, and said solid cured polymer being capable of chemically bonding to active sites on the textile;
b) applying said polymer-forming composition to the textile; and
c) exposing the textile to a source of energy under such conditions as to generate chemically active sites on the textile, curing the polymer-forming composition to provide a polymer, and forming chemical bonds between the textile and the cured polymer.
The method advantageously produces a soft, adherent coating on the textile such that the textile retains its feel as well as color fastness. Moreover, the composition contains no VOCs and is readily dispersible in water.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
While the present invention is particularly applicable to coatings and inks applied by silk screen methods, it should be understood that any coating application, for printing or non-printing purposes, is within its scope. The term “coating” as used herein shall be understood as including, inter alia, printing indicia onto the textile with an ink, as well as coating the textile overall with a colored or non-colored composition. Percentages of materials are by weight unless stated otherwise. Note that all quantities appearing hereinafter shall be understood to be modified by the term “about” except in the Examples and unless indicated otherwise.
The substantially water-free, energy-curable, polymer-forming composition herein includes an acrylate oligomer having at least two polymerizable ethylenically unsaturated moieties, and an alkoxylated polyol monomer having at least two ethylenically unsaturated moieties. Preferably, a surface active agent which is capable of being integrated into the molecular structure of the polymer resulting from the copolymerization of the acrylate oligomer and the alkoxylated polyol monomer is also included as a component of the composition. As mentioned below, the integration of the surface active agent can be by covalent bonding or hydrogen bonding. The surface active agent renders the composition water-dispersible.
The acrylate oligomer can be selected from epoxy acrylate oligomer, polyester acrylate oligomer, and polyurethane acrylate oligomer. Suitable acrylate oligomers are discussed in greater detail below.
Generally, the energy-polymerizable composition of the present invention includes the following component weight percentages:
Oligomers
30%-70%
Monomers
30%-70%
Surfactants
0 to about 20%
Photoinitiators
0-10%
The epoxy acrylate oligomer can be prepared by reacting an epoxide with an unsaturated acid such as acrylic or methacrylic acid, optionally in the presence of a polyamide derived from a polymerized fatty acid.
In one embodiment the epoxy acrylate oligomer is derived from a compound having the formula:
R
1
—[—CH
2
—CHOH—CH
2
—O(O)C—CH═CH
2
]
n
wherein R
1
is an aliphatic, aromatic or arene moiety having at least two carbon atoms and at least two oxido residues, and n is an integer of from 2 to 6.
Useful epoxides include the glycidyl ethers of both polyhydric phenols and polyhydric alcohols, epoxidized fatty acids or drying oil acids, epoxidized diolefins, epoxidized di-unsaturated acid esters, as well as epoxidized unsaturated polyesters, preferably containing an average of more than one epoxide group per
Calderone Adrian T.
Dilworth Peter G.
Drach John E.
Henkel Corporation
Moore Margaret G.
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