Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Coated or impregnated woven – knit – or nonwoven fabric which... – Coating or impregnation improves soil repellency – soil...
Reexamination Certificate
1999-01-11
2001-03-27
Copenheaver, Blaine (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Coated or impregnated woven, knit, or nonwoven fabric which...
Coating or impregnation improves soil repellency, soil...
C442S168000, C442S414000
Reexamination Certificate
active
06207594
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a fibrous polyamide substrate having durable resistance to staining by acid colorants and to a method of rendering a fibrous polyamide substrate durably resistant to staining by acid colorants.
2. Description of Prior Art
Fibrous polyamide substrates, such as nylon carpeting are susceptible to staining by both naturally occurring and commercial acid colorants found in many common foods and beverages. The demand for reduced staining from such acid colorants has by and large been met previously by treatment with compositions comprising sulfonated napthol and or phenol or sulfonated phenol-formaldehyde condensation products as disclosed for example in the following patents: U.S. Pat. No. 4,501,591, Ucci and Blyth; U.S. Pat. No. 4,592,940, Blyth and Ucci; U.S. Pat. No. 4,680,212, Blyth and Ucci; U.S. Pat. No. 4,780,099, Creshler, Malone and Zinnato; and U.S. Pat. No. 4,865,885, Herlant and Al, or by treatment with compositions comprising sulfonated novalak resins together with polymethacrylic acid as disclosed in U.S. Pat. No. 4,822,373 (Olson, Chang and Muggli). The use of polymers or copolymers of methacrylic acid of low weight average molecular weight and low number average molecular weight is described in U.S. Pat. No. 4,937,123 (Chang, Olson and Muggli).
The initial stain resistance properties imparted to polyamide substrates, such as carpeting, that have been treated using the above mentioned compositions degenerate significantly with each wet cleaning the substrate receives. Improved stain resistance after wet cleaning can be achieved by increasing the amount of the phenolic resin in the stain resist product or by increasing the amount of stain-resist product initially applied to the substrate, however, this generally leads to discoloration caused by yellowing of the substrate initially and further discoloration upon exposure to oxides of nitrogen and/or light. This discoloration in most cases is attributed to dihydroxydiphenol sulfone and its associated SO
2
group.
Stain resist products currently available in the market place are generally novalak—type resins based on dihydroxydiphenyl sulfone and phenol sulfonic acid condensed with aldehyde in acid media, or dihydroxy diphenyl sulfone and naphthalene sulfonic acid condensed with aldehyde at low pH.
It is generally known that increasing the ratio of dihydroxydiphenyl sulfone to the phenol sulfonic acid or napththalene sulfonic acid increases the stain resistance properties of the resin and subsequently causes a higher degree of yellowing or discoloration initially and further discoloration upon exposure to oxides of nitrogen and/or light.
It is also evident that when the ratio of phenol sulfonic acid or naphthalene sulfonic acid to dihydroxydiphenyl sulfone increases, the result is lower stain-resist properties and less discoloration.
The addition of acrylic polymers and/or copolymers to the previously mentioned novalak resin condensation products as disclosed in U.S. Pat. No. 4,822,373 (Olson, Chang and Muggli) allows the use of a novalak resin in small quantities and larger quantities of the acrylic resin. With this combination of novalak resin and acrylic resin, big improvement in the light fastness or less discoloration is achieved due to the dramatically reduced percentage of novalak resin in the product mentioned above which is adjusted to obtain a desired minimum level of discoloration while maintaining a maximum level of durability to wash. The high level of initial stain resistance is supplied primarily by the methylacrylic polymer and/or copolymer and after wet cleaning the stain resistance is supposedly maintained by the novalak resin, the acrylic having largely been removed during the wet cleaning process.
SUMMARY OF THE INVENTION
It is an object of this invention to provide fibrous polyamide substrates having durable resistance to staining by acid colorants.
It is a further object of this invention to provide a method of rendering a fibrous polyamide substrate durably resistant to staining by acid colorants.
It is a particular object of this invention to provide such a substrate or method in which a treating solution is employed which contains a combination of semi-soluble or insoluble and insoluble acrylic resins particularly of high weight average and number average molecular weight, to produce high stain resistance and durability to wet cleaning process to reduce the need for phenolic resin or to eliminate it completely, and to provide an optimum light fastness and minimum discoloration of the polyamide substrate due to nitrogen oxides or light.
In accordance with one aspect of the invention there is provided a fibrous polyamide substrate having resistance to staining by acid colorants, said fibrous polyamide substrate having applied thereto a combination of:
a) a semi-soluble or insoluble ethyl methacrylate polymer; and
b) a soluble or semi-soluble methacrylic acid polymer.
In accordance with another aspect of the invention there is provided an aqueous formulation for providing resistance to staining by acid colorants in fibrous polyamide substrates comprising:
a) a semi-soluble or insoluble ethyl methacrylate polymer, and
b) a soluble or semi-soluble methacrylic acid polymer, and
c) an aqueous vehicle for said polymer.
In accordance with still another aspect of the invention there is provided a method of imparting stain resistance to acid colorants, to a fibrous polyamide substrate comprising contacting said fibrous polyamide substrate with an aqueous formulation comprising in an aqueous vehicle
a) a semi-soluble or insoluble ethylmethylacrylate polymer, and
b) a soluble or semi-soluble methacrylic acid polymer.
Preferably polymers a) and b) are both of high molecular weight.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the invention, it has been found that completely soluble acrylic and methacrylic homopolymers and copolymers do not have durability to wet cleaning, so that their stain resist effect diminishes with wet cleaning; whereas completely insoluble acrylic resins have very little or no stain resist effect on polyamide fibers.
The present invention employs a combination of two or more acrylic resins, one of which has sufficient solubility and the other sufficient insolubility, so that in combination there is a synergetic effect between the resins and polyamide fibers of a polyamide substrate and the resins are resistant to wet cleaning processes, thereby providing durable stain resistance, the combination also provides initial stain resistance, prior to wet cleaning of the polyamide fiber substrate as well as a soil release effect.
The combination improves the light fastness and reduces the discoloration or yellowing caused by heat nitrogen oxides or light.
Suitably the semi-soluble or insoluble ethyl methacrylate polymer component a) is a homopolymer of ethylmethacrylate or a copolymer of ethylmethacrylate and at least one comonomer, for example, ethylacrylate, methylacrylate, methylmethacrylate, methacrylic acid, butylmethacrylate, isobutyl methacrylate or 2-ethylhexylmethacrylate. An especially preferred comonomer is methacrylic acid.
The ethyl methylacrylate polymer a) suitably has a high weight average molecular weight of at least 100,000 to 500,000, and preferably 100,000 to 250,000, and more preferably 100,000 to 170,000, and a high number average molecular weight of at least 25,000 to 100,000, preferably 35,000 to 75,000, and more preferably 30,000 to 60,000.
The soluble or semi-soluble methacrylic acid polymer component b), is suitably a homopolymer of methacrylic acid or a copolymer of methacrylic acid and at least one comonomer, for example, ethylacrylate, 2-ethylhexylmethacrylate, ethylmethacrylate, methylmethacrylate, butyl methacrylate or isobutyl methacrylate.
The methacrylic acid polymer b) suitably has a high weight average molecular weight of at least 100,000, typically 100,000 to 500,000, and preferably 150,000 to 250,000, more preferably over 200,000; and a high number average molecula
Copenheaver Blaine
Pratt Christopher C.
Swabey Ogilvy Renault
Trichromatic Carpet Inc.
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