KR20010100018A - Water-dispersible Nonwoven Fabrics Containing Temperature-sensitive Or Ion-sensitive Polymeric Binder Materials And Process For Making Such Fabrics - Google Patents

Abstract

The present invention relates to a temperature-sensitive or ion-sensitive binder composition containing at least one temperature-sensitive or ion-sensitive polymeric material. The binder composition is (1) water insoluble in water containing more than about 0.5 weight percent monovalent ions or water having a polyvalent ion concentration in excess of about 200 ppm and containing less than about 0.5 weight percent monovalent ions or Soluble in water with a polyvalent ion concentration of less than about 200 ppm; Or (2) the binder composition is insoluble in water having a temperature above about 30 ° C. and soluble in water having a temperature below about 25 ° C. The present invention additionally relates to water-dispersible nonwovens containing ion-sensitive or temperature-sensitive binder materials, which are useful for the preparation of washable personal care products. Also provided is a method of making a water dispersible nonwoven.

Description

Water-dispersible Nonwoven Fabrics Containing Temperature-sensitive Or Ion-sensitive Polymeric Binder Materials And Process For Making Such Fabrics}

Personal care products (e.g., ear muffs, sanitary napkins, wipes, wound dressings, bandages, nursing pads, and adult incontinence) are generally made of many different elements and materials. The main materials of personal care products are cover materials (ie liners) and absorbent (ie surge) materials, which typically include nonwovens. In these applications, the terms "nonwoven", "nonwoven fibrous web", "fabric", "fabric web", and "fabric substrates" may be used interchangeably and are melt blown. methods of making such fabrics and webs, such as meltblowing, meltspinning, airlaying and wet laying methods.

Surge materials should be made to receive and absorb various liquids, and liner materials should be made to prevent or minimize the leakage of such liquids.

Although personal care products are relatively inexpensive, hygienic and easy to use, there is a problem with proper disposal of contaminated products. Today's growing interest in environmental protection requires the development of materials that are more compatible with existing water disposal technologies and developing water treatment technologies, while delivering the performance consumers expect and demand. . An ideal alternative treatment is to use municipal sewage treatment and private resident purification systems. Products suitable for treatment with sewage systems can be washed down in a flush toilet and are referred to as "flushable". To function effectively as a liner and surge material, a nonwoven must maintain its structural integrity and exhibit satisfactory tensile strength when wet or wet. However, if the nonwovens are exposed to water and substantially lose their tensile strength and become dispersible in such water, treatment problems can be substantially eliminated. Thus, these materials can be conveniently washed off in conventional toilet systems.

Preferably, the nonwoven has a number of properties such as flexibility and flexibility. Such fabrics are formed by wet or dry laying any of a number of fibers and then bonding together to form a coherent web. Unfortunately, in attempts to provide nonwovens with properties in certain uses, conventional methods have made the fabric non-dispersible in water. For example, nonwovens have been bonded using fluid insoluble resins that impart strength in use. However, these resins have made the fabric substantially water insoluble and prevented it from being washed away.

In the case of pre-wet handkerchiefs, special problems arise. Handkerchiefs used for skin cleanness and commercially known as towels, wet wipes or fem-wipe are formed from nonwoven fibrous webs or paper treated with a polymeric binder. The binder imparts a wet strength to the web that is sufficient to maintain tensile strength while the web is preserved in a suitable liquid medium. However, after the handkerchief is used, the binder should be easily weakened without blocking the toilet and sewer pipes when exposed to an aqueous environment such as the toilet.

Various binders have been used in the manufacture of handkerchiefs. For example, towels have included, as binders, acid-insoluble, alkali-soluble polymer polycarboxylic acids and functional derivatives thereof (wherein the acid is placed in water and all acid groups are applied before the binder is applied to the web). Sufficient alkali is added to substantially neutralize). The binder-saturated web is dried and then immersed in a low pH medium (where the web maintains its structural integrity, but will still be compromised if the handkerchief is immersed in a sufficiently high pH liquid medium).

Another binder used in the pre-wet handkerchief was polyvinyl alcohol mixed with an insolubilizer or gelling agent such as borax. Borax crosslinks at least the surface of the polymeric binder prior to drying the web to provide a water resistant web. Such crosslinking is reversible such that the degree of crosslinking is low enough that the binder becomes water soluble when the concentration of borax is reduced below a certain level. However, boron-containing solutions are not acceptable for personal care products due to safety concerns.

Another water-dispersible nonwoven has used water soluble binders that include partially neutralized unsaturated carboxylic acid / unsaturated carboxylic acid ester copolymers. The problem with the use of such a binder is that the handkerchief must be maintained in a solution having a certain pH to prevent the nonwoven fibrous web from breaking down prior to disposal, which can irritate the skin when using the handkerchief.

Binders containing carboxylate groups work well in the production of water dispersible fibrous webs that are water soluble, water dispersible or water degradable to a limited extent, when water generally does not contain divalent ions. However, where water is "moderately hard", handkerchiefs are not easily dispersed because water contains divalent ions such as calcium ions or magnesium ions. The water soluble polymer binder becomes substantially insoluble due to the presence of divalent ions. It is believed that divalent ions crosslink the binder to inhibit the binder from dispersing in water. The adverse effect of the divalent ions present in the aqueous environment on the water solubility of the polymeric binder was not recognized.

Accordingly, there is a need for a water dispersible binder composition that can be used in personal care products such as handkerchiefs, can be used safely, and is substantially unaffected by the presence of divalent ions commonly found in mild hard water. .

The present invention relates to a water dispersible nonwoven fabric. In a more specific aspect, the present invention relates to a water dispersible nonwoven fabric containing a temperature-sensitive or ion-sensitive polymer binder material. The present invention also relates to a process for producing such water dispersible nonwovens.

Summary of the Invention

Briefly described, the present invention provides a water dispersible nonwoven fabric that can be used in washable personal care products. More specifically, the present invention provides a water dispersible nonwoven that contains a temperature-sensitive or ion-sensitive polymer binder material.

The present invention also provides a method of making a water dispersible nonwoven wherein the fibers used to form the nonwoven are bound together with a temperature-sensitive or ion-sensitive polymeric binder material.

The present invention further provides a washable personal hygiene product made from the water dispersible nonwoven provided by the present invention.

These and other objects, features and advantages of the present invention will become apparent from the following detailed description.

<Detailed Description of the Invention>

The present invention relates to a binder composition that can be used to prepare nonwovens for use in washable personal care products. The binder composition has the unique property of making a "water dispersible" product. The binder composition of the present invention may be "ion-sensitive" or "temperature-sensitive", or may be ion-sensitive and temperature-sensitive. In order to be "ion-sensitive" or "temperature-sensitive" effective for use in washable personal care products, the binder composition is preferably 1) functional (i.e., to maintain wet strength under controlled conditions and to wash or sink worldwide Rapidly dissolved or dispersed in soft or hard water as found in 2) safety (non-toxic); And 3) economics.

As used herein, the term "ion-sensitive" refers to the solubility and dispersion of the binder composition in which the monovalent and / or polyvalent ions present in the aqueous solution vary depending on the amount. As used herein, the term "monovalent" refers to ions having a charge of 1, such as Na ⁺ and Cl ^- ions. As used herein, the term "multivalent" refers to ions having a charge greater than 1, such as Ca ²⁺ and CO ₃ ^2- . In the present invention, the "ion-sensitive" binder composition remains insoluble in aqueous compositions having monovalent salt concentrations greater than about 0.5% by weight or polyvalent ion concentrations greater than about 200 ppm. However, “ion-sensitive” binder compositions are soluble in aqueous compositions having a monovalent salt concentration of less than about 0.5 weight percent or a polyvalent ion concentration of less than about 200 ppm.

In order to be effective as a binder material in washable products in the United States, the ion-sensitive binder compositions of the present invention remain stable and maintain their integrity upon drying or in high concentrations of monovalent and / or polyvalent ions, but at about 200 ppm Ca ^Soluble in water below ²⁺ ion concentration. Preferably, the ion-sensitive binder composition of the present invention is insoluble in a salt solution containing at least about 0.5% by weight of one or more inorganic and / or organic salts containing monovalent and / or polyvalent ions. More preferably, the ion-sensitive binder compositions of the present invention are insoluble in salt solutions containing about 0.5% to about 5.0% by weight of one or more inorganic and / or organic salts containing monovalent and / or polyvalent ions. to be. Even more preferably, the ion-sensitive binder composition of the present invention is in a salt solution containing about 0.5% to about 3.0% by weight of at least one inorganic and / or organic salt containing monovalent and / or polyvalent ions. Insoluble. Suitable, monovalent and / or polyvalent ions are Na ⁺ ions, K ⁺ ions, Li ⁺ ions, NH ₄ ⁺ ions, Cl ⁻ ions, Ca ²⁺ ions, Mg ²⁺ ions, Zn ²⁺ ions, CO ₃ ^2- Ions, SO ₄ ^2- ions and combinations thereof.

In the light of recent research conducted by the American Chemical Society, the hardness of the United States' water hardness is very variable, and for CaCO ₃ concentrations, about 500 ppm CaCO ₃ (about 200 ppm Ca ²⁺ ions) It is in the range of. To ensure polymer dispersibility throughout the United States, the ion-sensitive binder compositions of the present invention should preferably be soluble in water containing up to about 50 ppm Ca ²⁺ and / or Mg ²⁺ ions. More preferably, the ion-sensitive binder composition of the present invention should be soluble in water containing up to about 100 ppm Ca ²⁺ and / or Mg ²⁺ ions. Even more preferably, the ion-sensitive binder composition of the present invention should be soluble in water containing up to about 150 ppm Ca ²⁺ and / or Mg ²⁺ ions. Even more preferably, the ion-sensitive binder composition of the present invention should be soluble in water containing up to about 200 ppm Ca ²⁺ and / or Mg ²⁺ ions.

Furthermore, the term "temperature-sensitive" as used herein refers to the solubility and dispersion of the binder composition that varies with the temperature of the aqueous solution. In the present invention, the "temperature-sensitive" binder composition remains insoluble in aqueous compositions having temperatures above about 37 ° C. However, "temperature-sensitive" binder compositions become soluble in aqueous compositions having a temperature of less than about 20 ° C. Preferably, the “temperature-sensitive” binder composition remains insoluble in the aqueous composition having a temperature above about 32 ° C. and becomes soluble in an aqueous composition having a temperature below about 22 ° C. More preferably, the “temperature-sensitive” binder composition remains insoluble in the aqueous composition having a temperature above about 30 ° C. and becomes soluble in an aqueous composition having a temperature below about 25 ° C.

The binder composition of the present invention comprises at least one polymer material that is ion-sensitive or temperature-sensitive, or ion-sensitive and temperature-sensitive. Suitable ion-sensitive and / or temperature-sensitive polymer materials include poly (vinyl alcohol), poly (vinyl methyl ether), hydroxypropyl cellulose, alkyl hydroxypropyl cellulose (eg methyl hydroxypropyl cellulose) and their Combinations include, but are not limited to. The binder composition of the present invention comprises at least 100% by weight of at least one ion-sensitive and / or temperature-sensitive polymer material. Preferably, the binder composition of the present invention comprises about 25 to about 99 weight percent of at least one ion-sensitive and / or temperature-sensitive polymer material and about 75 to about 1 weight percent of at least one "other polymer". Include. As used herein, the term “other polymers” refers to polymers that do not have ion-sensitivity and temperature-sensitivity as described above. More preferably, the binder composition of the present invention comprises about 40 to about 95 weight percent of at least one ion-sensitive and / or temperature-sensitive polymer material and about 60 to about 5 weight of at least one "other polymer". Contains% Even more preferably, the binder composition of the present invention comprises about 40 to about 75 weight percent of at least one ion-sensitive and / or temperature-sensitive polymer material and about 60 to about 25 of at least one "other polymer". It contains by weight.

Suitable other polymers include aqueous dispersions of water-soluble binders such as polyvinyl alcohols such as polyvinyl chloride, polyacrylates and copolymers of acrylates and methacrylates; Polyolefins, polyacrylates grafted with polar functional groups such as polystyrene, styrene-acrylonitrile copolymers, acrylonitrile-butadiene-styrene terpolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, hydroxyl groups , Polymethacrylate, polyvinyl butyral, polyurethane, polyester, polyamide, polyvinyl acetate, polyethylene vinyl acetate, ethylene vinyl alcohol copolymers, and combinations thereof. It should be noted that all grades of polyvinyl alcohol, including water-insoluble grades, can be used as other polymers. Preferably, the other polymer comprises at least one water soluble binder, such as polyvinyl alcohol, polyvinyl acetate, polyvinyl chloride, polyacrylate, and a copolymer of acrylate and methacrylate. Ion-sensitive / or temperature so long as the resulting binder composition blend has desirable characteristics suitable for use in water-dispersible articles (ie, ion-sensitive and / or temperature-sensitive solubility, dispersibility in cold water, etc.). The choice and number of sensitive polymer materials is not limited.

According to one embodiment of the invention, the binder composition comprises about 25% to about 99% by weight of at least one polymeric material selected from poly (vinyl alcohol), poly (vinyl methyl ether) and methyl hydroxypropyl cellulose and about polyvinyl acetate 75 to about 1 weight percent.

In some embodiments, it may be desirable to use one or more additives in the binder composition of the present invention. Suitable additives are, but are not limited to, antioxidants, antistatic agents, blowing agents, compatibilizers, flame retardants, heat stabilizers, impact modifiers, lubricants, depending on the specific properties required in the binder composition and the products made therefrom. , Plasticizers, ultraviolet stabilizers, processing aids, dispersants, slip formulations, perfumes, colorants, antifoams, fungicides, bacteriostatic agents, surface active agents, thickeners, fillers and the like. Typically, such additives are included in the binder composition of the present invention in an amount up to about 10% by weight of the total weight of the binder composition.

In one embodiment of the invention, a plasticizer is included in the binder composition described above. Suitable plasticizers include, but are not limited to, glycerol; Sorbitol; Emulsified mineral oil; Dipropylene glycol dibenzoate; Polyglycols such as polyethylene glycol, polypropylene glycol and copolymers thereof; Decanoyl-N-methylglucamide; Tributyl citrate; And tributoxyethyl phosphate, and may be added to a solution containing the binder composition.

One advantage of the polymer binder compositions of the present invention is that they are relatively insensitive to divalent cations found in hard water because of the lack of crosslinking sites along the ion-sensitive and / or temperature-sensitive polymer compositions of the composition. Unlike other binder compositions, the binder compositions of the present invention have flexible applicability for various end application applications due to the unique properties of the binder materials.

The binder composition of the present invention is particularly useful for making "water-dispersible" nonwovens. As used herein, the term "water-dispersible" is used in cold water (about 25) or in water with low ionic content (water having a monovalent salt concentration of less than about 0.5% by weight or polyvalent ion concentration containing less than about 200 ppm). Refers to the ability of the fabric to degrade and / or disperse into several pieces of fabric when stirred at &lt; RTI ID = 0.0 &gt; Preferably, the water-dispersible fabrics are each less than about 50%, preferably less than about 20%, compared to the size predispersed within about 20 minutes, preferably within about 10 minutes and more preferably within about 2 minutes in an aqueous environment. Is separated into several pieces having an average size of less than about 40%, and more preferably less than about 30%. The term "nonwoven" as used herein refers to a fabric having a structure of individual fibers or filaments, optionally arranged in a mat-like form. Nonwoven fabrics include, but are not limited to, air-laid processes, wet-laid processes, hydroentangling processes, staple fiber carding, and bonding. , And solution spining.

Nonwoven fabrics made according to the invention have good tensile strength on drying, but are easily dispersed at low ionic content or at low temperatures. Nonwovens are friction durable and maintain significant tensile strength in aqueous solutions containing high concentrations of salts or having temperatures higher than the "trigger temperature" of the polymeric material. As used herein, the term “trigger temperature” means the turbidity temperature or lower critical solution temperature (LCST) of the temperature-sensitive polymer material. In one embodiment of the invention, the polymeric material may be further insolubilized by adding a suitable organic solvent to water to form a "non-cosolvency effect". As used herein, the term "non-colytic effect" refers to a "poor solvent" (ie, a given polymeric material) from two or more "good solvents" (ie, solvents in which each of the independent solvents may have a good solubility). Means a mixture of two or more solvents having a very low solubility thereof. Suitable organic solvents for forming the non-colytic effect include, but are not limited to, methanol and ethanol.

Preferably, the nonwovens of the present invention can be readily dispersed in soft or mild hard water. As used herein, the term "soft water" means water having a divalent ion content of less than about 10 ppm. As used herein, the term “warm hard water” is water having a divalent ion content of about 10 to about 50 ppm. The term "hard water" as used herein is water having an ionic content of greater than about 50 ppm. Because of this latter property, the nonwovens of the present invention are suitable for disposable personal care products that can be disposed of in used flush toilets, such as sanitary napkins, diapers, dry handkerchiefs and pre-wet handkerchiefs.

Binder materials are particularly useful for bonding fibers of air-laid nonwovens. These air-laid materials are particularly useful for, but not limited to, a variety of products, including: body-side liners, fluid distribution materials, fluid absorber materials (eg, surge materials) and absorbent wraps wrap sheets and cover stock for various water dispersible personal care products. Air-laid materials are particularly useful for use as pre-wet handkerchiefs. The basis weight of these air-laid nonwovens is preferably in the range of about 20 to about 200 grams (about 20 to about 200 gsm) per square meter. Surge materials or absorbent materials that require good resilience and high loft are preferably staple fibers having at least about 6 denier for making these products. Preferred final densities for the surge material or absorber material are from about 0.025 to about 0.050 g / cc (grams per cubic centimeter). The fluid distributing material will have a greater density and is preferably about 0.10 to about 0.20 g / cc with fibers having a low denier.

The nonwovens of the present invention may be formed from natural fibers, synthetic fibers and combinations thereof. The choice of fiber depends, for example, on the cost of the fiber and the intended use of the finished fabric. Examples of suitable fibrous substrates that may be used alone or in combination include cotton, relene, hemp, jute, wool, wood pulp, recycled cellulosic fibers (eg viscose rayon), modified cellulosic fibers (Cellulose acetate), or synthetic fibers derived from polyvinyl alcohol, polyester, polyamide, polyacryl, and the like. Blends of one or more of the fibers may also be used. In one embodiment of the present invention, a combination of wood pulp and synthetic artificial fibers is used to form a nonwoven fabric. Preferably, synthetic artificial fibers have a fiber denier of less than about 1.5.

In an additional embodiment of the present invention, the nonwoven is formed from relatively short fibers (eg wood pulp fibers). The minimum length of the fiber depends on the method chosen to form the nonwoven. For example, when the fibrous substrate is formed by carding, the length of the fiber should typically be at least about 42 mm to ensure homogeneity. When the fibrous substrate is formed by an air-laid or wet-rate process, the fiber length may preferably be about 0.1 to about 15 millimeters. Although fibers having a length greater than 50 mm are within the scope of the present invention, if a substantial amount of fibers having a length greater than about 15 mm is included in the washable fabric, the lengths of the fibers, even if they are dispersed and degraded in water, It has been determined that water washing in domestic toilets tends to form undesirable "ropes". Thus, for these products, it is desirable that the fiber length is about 15 mm or less so that the fibers do not have a tendency to form "ropes" when washed through the toilet bowl. Fibers of various lengths are applicable to the present invention, but preferably the lengths of the fibers should be less than about 15 mm so that the fibers should readily disperse with each other when they come in contact with water, Most preferred. Preferably, the nonwovens of the present invention should have a relatively low cohesive force in tap water and sewage so that the fabric can be readily decomposed from the agitation provided by flush and movement through the sewer pipe.

The nonwoven fabric of the present invention may be formed in a single layer or multiple layers. In the case of multiple layers, the layers generally overlap in a parallel or surface-to-surface manner, and all or part of the layers can be joined to adjacent layers. The nonwoven may be formed from a plurality of separate nonwovens, where the separated nonwovens may be formed in a single layer or multiple layers. The binder may be distributed as a single application on the nonwoven, or in the case of multiple layers, the binder may be applied to each layer individually and then combined in parallel fashion with the other layers to form the finished nonwoven.

Another embodiment of the invention is a method of making a water dispersible nonwoven. The method comprises contacting a fibrous substrate with an effective amount of the binder composition of the present invention to bind a substantial amount of fibers, and then drying the fabric to form a water dispersible fibrous fabric. In order to easily apply the binder to the nonwovens, the dispersant may be emulsified, dispersed and / or dissolved in water or other solvents such as methanol and ethanol and the like (water is the preferred solvent). The binder preferably has about 1 to about 50 weight percent solids, more preferably about 2.5 to about 20 weight percent solids.

The binder material may be applied to the nonwoven by any known method such as spraying, dipping, printing, coating or any other technique. When the binder is applied to the nonwoven to maintain the integrity of the fabric, the binder is preferably dispersed substantially throughout the fabric to form substantially all of the fiber bonds. Based on the total weight of the nonwovens, the binder is preferably from about 1 to about 50 weight percent, more preferably from about 5 to about 30 weight percent, even more preferably from about 8 to about 25 weight percent and most preferably It may be distributed or "added on" to the nonwoven in an amount of about 12 to about 18 weight percent.

Once the binder is applied to the fabric, the fabric can be dried by conventional methods. Once dried, the coherent fibrous fabric exhibits improved tensile strength compared to the tensile strength of similar but untreated wet-laid or dry-laid fabrics. For example, the tensile strength of the fabric can be increased by at least 25% relative to the untreated fabric. More specifically, the tensile strength of the fabric may be increased by at least about 100% relative to the untreated fabric, and even more specifically, the tensile strength of the fabric may be increased by at least about 500% relative to the untreated fabric. However, more advantageously, the fabric is one that can decompose or decompose when placed and stirred in soft or mild hard or cold water.

The water dispersible nonwoven of the present invention is particularly suitable for use in water dispersible products. Suitable products include, but are not limited to, handkerchiefs, sanitary napkins, diapers, surgical dressings, tissues, and the like. In many products (particularly personal care products), nonwovens are preferred because of their fluid absorption, such as their blood, menstrual blood and urine. The nonwovens of the present invention may be incorporated into a variety of body fluid absorbent products, including, but not limited to, sanitary napkins, diapers, surgical dressings, tissues, and the like. The binder composition of the present invention can keep the resulting nonwovens intact when in contact with the body fluid because the concentration of divalent ions in the body fluid is higher than the level at which it can dissolve it. Nonwovens retain their structure and flexibility and meet strength requirements for practical use. However, the binder dissolves and the fabric disperses when contacted with water having either a low salt concentration (ie, about 0.5% by weight or less) or a temperature near room temperature. In one embodiment of the invention, the nonwoven is in the form of a handkerchief. The finished handkerchief may be individually packaged in a folded bag, individually in a waterproof bag or package in a container having any desired number of prefolded sheets, and loaded into the waterproof package with a humectant applied to the handkerchief. Can be. The wetting agent may be about 10 to about 400 weight percent of the dry weight of the handkerchief itself. Handkerchiefs must maintain their intended characteristics for periods involving packaging, transportation, retail display and consumer storage. Thus, the retention period may range from two months to two years.

Various forms of impermeable bags for containing wet-packed materials, such as handkerchiefs and towels, are well known in the art. Any of these can be used to wrap the pre-wet handkerchief of the present invention.

Those skilled in the art will readily appreciate that the binder compositions and fibrous substrates of the present invention can be advantageously used in the manufacture of absorbent personal hygiene products designed to be in contact with the body fluid. Such articles may comprise only a single layer of fibrous substrate or may comprise a combination of elements as described above. Although the binder compositions and fibrous substrates of the present invention are particularly suitable for personal care products, the binder compositions and fibrous substrates can be advantageously used in a wide range of consumer products. Furthermore, although the binder composition is particularly useful for the formation of nonwovens, the binder product may also be used for the formation of woven or knitted fabrics, where the binder composition is used as a fiber sizing material or a fiber coating material.

The invention is further illustrated by the following examples, which should not be construed as in any way limiting the scope of the invention. Conversely, various readings, modifications, and equivalents of the invention may be given to those skilled in the art without departing from the spirit of the invention and / or the scope of the claims after reading the description herein. It is clearly recognized.

Preparation of binder material

Binder No. One

The binder is based on polyvinyl alcohol and includes the following ingredients given in parts by weight:

157.2 parts of 15% by weight polyvinyl alcohol (15% by weight PVOH and 85% by weight water) sold under the name KP-6 from Nippon Gohsei Company;

42.8 parts by weight 55% polyvinyl acetate emulsion (55% by weight PVA and 45% by weight water), available under the trade name VINAC from Air Products, Inc .;

192 parts of water; And

Anhydrous sodium sulfate 3.93 parts.

Total solids content: 12.0% by weight.

In order to dissolve the polyvinyl alcohol in water, the desired amount of poly (vinyl alcohol) powder was added slowly to a well stirred 80-90 ° C. hot water. The hot slurry was cooled to room temperature with continued stirring. Stirring was continued until all particles had dissolved and the gel was gone from solution. High shear agitation was required to fully disperse the polyvinyl alcohol when added to water, but does not require a subsequent dissolution step.

Alternatively, to dissolve the polyvinyl alcohol in water, the desired amount of polyvinyl alcohol was added to water at room temperature with stirring. Stirring was continued until the polyvinyl alcohol dissolved. In this method, the time factor was more important than the high shear to ensure complete dissolution of the gel particles.

To prepare the binder solution, the desired amount of sodium sulfate was dissolved in water, then this solution was added to the polyvinyl alcohol solution with stirring, followed by addition of the polyvinyl acetate emulsion. The viscosity of the final binder composition was about 68 centipoise, but the composition was not stable, indicating phase separation upon standing. However, the stirring regenerated the homogeneous composition.

Binder No.2

The binder is based on polyvinyl methyl ether and includes the following components given in parts by weight:

7.50 parts of a polyvinyl methyl ether solution obtained as a 50% by weight solid solution registered by BASF Corporation under the trademark LUTANOL M-40;

72.05 parts of demineralized water; And

20.45 parts of a polyvinyl acetate emulsion as in binder No. 1.

Total solids content: 15.0% by weight.

Polyvinyl methyl ether solution was added to demineralized water at room temperature. After complete mixing, the polyvinyl acetate emulsion was added with vigorous stirring to obtain a homogeneous mixture. The composition was phase separated upon standing, but a vigorous stirring regenerated the homogeneous mixture. The viscosity of the final binder composition was about 41 centipoise.

Binder No. 3:

The binder is based on methyl hydroxypropyl cellulose and includes the following components given in parts by weight:

83.0 parts of methyl hydroxypropyl cellulose; And

17.0 parts of a polyvinyl acetate emulsion as in binder No. 1.

Total solids content: 12.0% by weight.

The desired amount of methyl hydroxypropyl cellulose powder (purchased under the trademark BENECEL MP-943 from Aqualon Chemical Company) was added to demineralized water at 70-75 ° C. Under vigorous stirring, the water temperature was lowered to room temperature. Stirring was continued until all powder had dissolved.

Polyvinyl acetate was added to this solution with vigorous stirring. Stirring was continued until a homogeneous mixture was obtained. The composition was phase separated upon standing, but a vigorous stirring regenerated the homogeneous mixture. The viscosity of the final binder composition was about 50 to about 200 centipoise.

Binder No. 4:

The binder is based on poly (vinyl methyl ethyr) and includes the following components given in parts by weight:

15.0 parts of a polyvinyl methyl ether solution as in binder No. 2;

71.4 parts of demineralized water; And

13.6 parts of vinyl acetate-ethylene emulsion sold by Air Products, Inc. under the trademark AIRFLEX 300.

Total solids content: 15.0% by weight.

Polyvinyl methyl ether solution was added to demineralized water at room temperature. After complete mixing, the vinyl acetate-ethylene emulsion was added with vigorous stirring to obtain a homogeneous mixture. The composition was phase separated upon standing, but a vigorous stirring regenerated the homogeneous mixture. The viscosity of the final mixture was about 40 to about 60 centipoise.

<Example 1>

Southern softwood Kraft fluff (SSWK) pulp from Rayonier (Jesup, GA) and 6 mm / 6 d / f (denier per filament) from KoSa; Charlotte, NC Binder No. 2 in a web containing 75 gsm (grams per square meter) of a mixture of polyesters (50: 50% by weight blend). 25 gsm sprayed 1 gave a web having a total basis weight of 100 gsm. This material was found to have some weak areas due to the high viscosity of the binder composition (which prevents it from covering the web with good spray). However, this material was found to have immediate wetting ability and to disperse in cold tap water.

Another web containing 90 gsm of the same fiber mixture was sprayed with a dilute solution of binder No. 1 at a level of 10 gsm. Observing the low spray cone angle (about 25 degrees) it was evident that the spray of binder was poorly covered. Good bulk (about 3 mm thickness) and low density (0.03 g / cm ³ ) were obtained, which is important for designing good fluid in-take materials.

<Example 2>

Binder No. was added to a web containing 95 gsm of the trademark CEMFIBER (Varde, Denmark) polypropylene (6 mm / 2 d / f) and Rayonierre SSWK pulp (50:50 wt% blend). 5 gsm spray of 1 gave a web having a total basis weight of 100 gsm. Again, it was observed that the spray was poorly covered because of the low cone spray angle. This material was found to be dispersed in cold water in the case of tap water.

<Example 3>

Binder No. 2 was applied to a web containing 23 gsm trademarked CEMFIBER propylene (6 mm / 2 d / f) formed on a tissue carrier web. 2 gsm sprayed 1 gave a web having a total basis weight of 25 gsm. Poor web formation was observed with straight polypropylene fibers and binder was found to migrate mostly to the tissue carrier web, which produced a weakly bound material.

A second web was formed using 80% by weight of trademark CEMFIBER polypropylene (6 mm / 2 d / f) and 20% by weight of Rayonier SSWK pulp. The web had improved fiber formation, but the high viscosity of binder No. 1 caused one side of the web to bond and the other side to only weakly bond due to poor permeability.

<Example 4>

Rayon fibers (6 mm / 3d / f) and Rayonier SSWK pulp (75:25 wt% blend), available under the trademark TENCEL from Accordis Cellulosic Fibers, Inc. (Mobile, AL). One side of the web containing 28 gsm was sprayed with 8 gsm of binder No. 2 to provide a web with a total basis weight of 36 gsm. Although the web is a "harsher" feel than the web containing polypropylene, the wettability was significantly improved immediately when using binder No. 2. The web remained intact when hot water (greater than 40 ° C.) was poured into the web, but the web was easily dispersed when immersed in cold tap water.

Similar fabrics were made, but the basis weight of the fiber blend was lowered to 24 gsm and binder no. 2 was applied at a level of 3 gsm per side. Rayon / pulp fiber formations with binders applied on both sides were “rough” to the polypropylene based web.

Example 5

A web containing a total weight of 37 gsm by spraying 4 gsm of binder No.2 per side onto a web containing 29 gsm of the trademark CEMFIBER polypropylene (6 mm / 2 d / f) and Layonier SSWK pulp (75:25 wt% blend) Provided. The second fabric was made while maintaining the fiber blend basis weight at 29 gsm, but binder no. 2 was sprayed to a level of 7 gsm on only one side to form a web with a total basis weight of 36 gsm. Polypropylene fibers were added to the fiber blend, but the web appeared to be somewhat rough to the touch. The added "harshness" was the result of the poly (vinylacetate) additive in binder No. 2. Both webs remained intact as the warm water passed through, but were easily broken down in cold tap water.

<Example 6>

Binder No. was added to the web containing 31 gsm of the trademark CEMFIBER polypropylene (6 mm / 2d / f) and Layonier SSWK pulp (75:25 wt% blend). 7 gsm sprayed on one side gave a web with a total basis weight of 38 gsm. As in the case of binder No. 1, the high viscosity of binder No. 3 interfered with a good spray pattern (about 45 degrees), causing the binder to be poorly covered on the web. This material had good instant wetting ability but was no better than the binder No. 2 based web.

<Example 7>

A web containing 31 gsm of the trademark CEMFIBER polypropylene (6 mm / 2 d / f) and Layonnier SSWK pulp (75:25 wt. Got it. A second fabric was prepared by reducing the fiber blend basis weight to 27 gsm and spraying binder No. 4 on both sides of the web at a level of 3 gsm per side, from which a web with a total basis weight of 33 gsm was provided. This binder showed a good spray pattern (90 degree cone angle) and was well covered in the web. The web is also very soft in touch, due to the polyvinylacetate-co-ethylene component in binder No. 4 (this component is less coarse than the polyvinylacetate component in binder No. 2). Like the web made from binder No. 2, the web made from binder No. 4 allows hot water to pass through without impairing the integrity of the web, but the web quickly decomposed when immersed in cold tap water. These webs were soft to the touch but did not have adequate integrity. The polyvinyl methyl ether component in binder No. 4 played a role in maintaining the integrity in hot water, but caused the web to decompose in cold tap water.

<Example 8>

A web containing 90 gsm of polyester (6 mm / 6 d / f) and Rayonier SSWK pulp (50:50 wt% blend) was sprayed with 5 gsm of binder No. 2 on both sides to provide a web with a total basis weight of 100 gsm. Binder No. 2 provided a web with good elasticity, high loft (3-4 mm thickness) and low density (0.03 g / cm ³ ) with rigid polyester fibers, which in-take surge) The intended initial requirements for the material were met. Upon contact with hot water, the web retained its elasticity and integrity, but degraded slowly in cold tap water. While the polyvinylacetate component in binder No. 2 is involved in good web integrity, polyvinyl methyl ether triggers a mechanism that allows the degradation of the web in cold water.

Example 9

Binder on both sides of the web containing 90 gsm of polyester (6 mm / 6 d / f) and Weihauser NB420 fluff pulp (50:50 wt% blend), available from Weyerhauser (Federal Way, WA) No. 2 was sprayed with 5 gsm to provide a web with a total basis weight of 100 gsm. As in Example 8, Weihauser pulp with the same combination of polyester fibers and binder No. 2 met the intended initial requirements for the in-take (surge) material. The purpose of making webs using two types of fibers is to later investigate the washability / dispersibility of the composite material and ultimately the effect of the fiber type on personal care products.

Although the invention has been described in detail with particular reference to particular embodiments, various modifications may be made without departing from the scope and spirit of the invention as defined in the following claims.

Claims (30)

(a) water insoluble in water containing more than about 0.5 weight percent monovalent ions or water having a polyvalent ion concentration in excess of about 200 ppm and less than about 0.5 weight percent monovalent ions or less than about 200 ppm Soluble in water having a polyvalent ion concentration of (b) insoluble in water having a temperature above about 30 ° C. and soluble in water having a temperature below about 25 ° C., A temperature-sensitive or ion-sensitive binder composition comprising at least one temperature-sensitive or ion-sensitive polymeric material. The binder composition of claim 1 insoluble in water having a polyvalent ion concentration of greater than about 200 ppm and soluble in water having a polyvalent ion concentration of about 50 to about 200 ppm. The binder composition of claim 1, wherein the binder composition is insoluble in water having a polyvalent ion concentration of greater than about 200 ppm and is soluble in water having a polyvalent ion concentration of about 100 to about 200 ppm. The binder composition of claim 1, wherein the binder composition is insoluble in water having a polyvalent ion concentration of greater than about 200 ppm and is soluble in water having a polyvalent ion concentration of about 150 to about 200 ppm. The binder composition of claim 1 which is insoluble in water having a monovalent ion concentration of greater than about 0.5% by weight and soluble in water having a monovalent ion concentration of less than about 0.3% by weight. The binder composition of claim 1, wherein the binder composition is insoluble in water having a temperature of about 30 to about 37 ° C. and is soluble in water having a temperature of about 25 to about 20 ° C. 7. The binder composition of claim 1 wherein the binder composition is insoluble in water having a temperature of about 32 to about 37 ° C. and is soluble in water having a temperature of about 25 to about 22 ° C. 7. The binder composition of claim 1 comprising from about 25 to about 99 weight percent of at least one ion-sensitive or temperature-sensitive polymer material and from about 75 to about 1 weight percent of at least one other polymer. The method of claim 1, wherein the at least one ion-sensitive or temperature-sensitive polymer material comprises poly (vinyl alcohol), poly (vinyl methyl ether), hydroxypropyl cellulose, methyl hydroxypropyl cellulose, or a combination thereof. Binder composition. A water-dispersible nonwoven comprising the fibers and the binder composition of claim 1. (a) water insoluble in water containing more than about 0.5 weight percent monovalent ions or water having a polyvalent ion concentration in excess of about 200 ppm and less than about 0.5 weight percent monovalent ions or less than about 200 ppm At least one temperature-sensitive or soluble in water having a polyvalent ion concentration of or (b) insoluble in water having a temperature above about 30 ° C. and soluble in water having a temperature below about 25 ° C. Temperature-sensitive or ion-sensitive binder compositions comprising ion-sensitive polymeric materials; And fiber Water-dispersible nonwoven comprising a. The nonwoven fabric of claim 11, wherein the binder composition is insoluble in water having a polyvalent ion concentration of greater than about 200 ppm and soluble in water having a polyvalent ion concentration of about 50 to about 200 ppm. The nonwoven fabric of claim 11, wherein the binder composition is insoluble in water having a polyvalent ion concentration of greater than about 200 ppm and soluble in water having a polyvalent ion concentration of about 100 to about 200 ppm. The nonwoven fabric of claim 11, wherein the binder composition is insoluble in water having a polyvalent ion concentration of greater than about 200 ppm and soluble in water having a polyvalent ion concentration of about 150 to about 200 ppm. The nonwoven fabric of claim 11, wherein the binder composition is insoluble in water having a monovalent ion concentration of greater than about 0.5 weight percent and soluble in water having a monovalent ion concentration of less than about 0.3 weight percent. The nonwoven fabric of claim 11, wherein the binder composition is insoluble in water having a temperature of about 30 to about 37 ° C. and soluble in water having a temperature of about 25 to about 20 ° C. 13. The nonwoven fabric of claim 11, wherein the binder composition is insoluble in water having a temperature of about 32 to about 37 ° C. and soluble in water having a temperature of about 25 to about 22 ° C. 13. The nonwoven fabric of claim 11, wherein the binder composition comprises from about 25 to about 99 weight percent of at least one ion-sensitive or temperature-sensitive polymer material and from about 75 to about 1 weight percent of at least one other polymer. The method of claim 11, wherein the binder composition comprises at least one ion-sensitive or temperature-sensitive polymer material comprising poly (vinyl alcohol), poly (vinyl methyl ether), hydroxypropyl cellulose, methyl hydroxypropyl cellulose or combinations thereof. Nonwoven fabric comprising a. A washable personal hygiene product comprising the water dispersible nonwoven of claim 11. (a) water insoluble in water containing more than about 0.5 weight percent monovalent ions or water having a polyvalent ion concentration in excess of about 200 ppm and less than about 0.5 weight percent monovalent ions or less than about 200 ppm At least one temperature-sensitive or soluble in water having a polyvalent ion concentration of or (b) insoluble in water having a temperature above about 30 ° C. and soluble in water having a temperature below about 25 ° C. Temperature-sensitive or ion-sensitive binder compositions comprising ion sensitive polymer materials; And fiber Washable personal care product comprising a water-dispersible nonwoven comprising a. The washable personal hygiene product of claim 21, wherein the binder composition is insoluble in water having a polyvalent ion concentration of greater than about 200 ppm and is soluble in water having a polyvalent ion concentration of about 50 to about 200 ppm. The washable personal hygiene product of claim 21, wherein the binder composition is insoluble in water having a polyvalent ion concentration of greater than about 200 ppm and is soluble in water having a polyvalent ion concentration of about 100 to about 200 ppm. The washable personal hygiene product of claim 21, wherein the binder composition is insoluble in water having a polyvalent ion concentration of greater than about 200 ppm and soluble in water having a polyvalent ion concentration of about 150 to about 200 ppm. The washable personal hygiene product of claim 21, wherein the binder composition is insoluble in water having a monovalent ion concentration of greater than about 0.5 weight percent and soluble in water having a monovalent ion concentration of less than about 0.3 weight percent. . The washable personal hygiene product of claim 21, wherein the binder composition is insoluble in water having a temperature of about 30 to about 37 ° C. and soluble in water having a temperature of about 25 to about 20 ° C. 23. The washable personal hygiene product of claim 21, wherein the binder composition is insoluble in water having a temperature of about 32 to about 37 ° C. and soluble in water having a temperature of about 25 to about 22 ° C. 23. The washable of claim 21 wherein the binder composition comprises from about 25 to about 99 weight percent of at least one ion-sensitive or temperature-sensitive polymer material and from about 75 to about 1 weight percent of at least one other polymer. Personal hygiene products. The method of claim 21, wherein the binder composition comprises at least one ion-sensitive or temperature-sensitive polymer material comprising poly (vinyl alcohol), poly (vinyl methyl ether), hydroxypropyl cellulose, methyl hydroxypropyl cellulose or combinations thereof. Washable personal hygiene products comprising a. The washable personal hygiene product of claim 21 comprising handkerchief, sanitary napkin, diaper, surgical dressing or tissue.