GB1594587A

GB1594587A - Waterproof textile laminates

Info

Publication number: GB1594587A
Application number: GB42816/76A
Authority: GB
Original assignee: Rohm and Haas Co
Current assignee: Rohm and Haas Co
Priority date: 1976-10-15
Filing date: 1976-10-15
Publication date: 1981-07-30
Also published as: DE2745950A1; BE859742A; FR2367608A1

Description

(54) WATERPROOF TEXTILE LAMINATES (71) We, ROHM AND HAAS ACCOMPANY, a corporation organized under the laws of the State of Delaware, United States of America, of Independence Mall West, Philadelphia, Pennsylvania 19105, United States of America, do hereby declare this invention to be described in the following statement:- This invention is concerned with waterproof laminates of fabric and crushed foam. The laminates of the invention are useful as materials for tents, raincoats, ground sheets, awnings, umbrellas and the like. In our copending U.K. application 25323/75, Serial No. 1514224, we have disclosed and claimed multiple crushed foam coated laminates coated with a finish coat. These laminates, which may be waterproof yet "breathable", are useful as simulated leather materials.The leather-like appearance depends upon the appearance surface being of coated crushed foam. It was hitherto believed that waterproof properties of such laminates were also predominantly provided by this exposed crushed foam layer since this, during the crushing process, is exposed to the crushing surface which, as a consequence, causes cell collapse, flow and fusion of the uncrushed cellular polymer. It was to be expected that the internal layers of foam, being protected from the crushing surfaces by relatively resilient and heat insulating fabric, would survive the crushing process with insufficient cell collapse, flow and fusion to give waterproof properties to the laminate.

We have now unexpectedly found, however, that a modification of the laminate of our earlier patent application wherein the exposed crushed foam/film is omitted retains sufficient resistancei i to water transmission to be useful as a tenting, ground sheet, rainwear, awning or umbrella material. Thus, the outer surface layers of the laminates of this invention are fabric layers rather than crushed foam or a finish film such as may be provided by a preformed film or finish coating composition.

By "waterproof" in this specification and claims we do not intend to be limited to total water impermeability but simply to indicate resistance to liquid water transmission sufficient for these purposes.

Accordingly, there is provided by our invention a waterproof (as hereinbefore defined) laminate of alternate fabric (as hereinafter defined) and crushed, collapsed foam layers made by crushing and curing a laminate of alternate layers of fabric and stable uncured foam formed on the fabric layer(s) and in which the outer layers are layers of fabric.

The fact that acrylic polymer may be used in the laminates of the invention, as will be described hereinafter, yields the outstanding advantage that relatively soft polymers of attractive cold flex properties may be used. Furtherniore, the waterproofing can be achieved without the necessity for multiple coats of waterproofing polymer being applied, as has been necessary in many conventional fabrics, in order to lay sufficient polymer onto the fabric. Any of the fabrics and polymers and of the coating, foaming and crushing techniques of our earlier patent specification can be used in the formation of the laminates of this invention so long as the heat and pressure applied is sufficient to collapse the cells of the uncrushed, dry foam and to cause flow and fusion of the polymer thereof.

Various natural and/or synthetic fabrics may be used in the laminates of this invention, such as the textile fabrics cotton, acetate, polyester, rayon, nylon and broadcloth. In addition to fabrics imitation leathers (poromerics) can be used and references to fabrics herein should also be regarded as referring to these materials.

The outer fabrics layers of the laminates of this invention may be the same as or different than, each other. For example, in one preferred embodiment one outer layer is of an abrasion-resistant hydrophobic textile, such as a woven nylon or poly(ethylene-terephthalate) fabric and the other layer is of cotton or another hydrophilic material. When the latter layer is placed on the inside of a tent or raincoat it provides an absorbent layer which counters "sweating" of the fabric. For awnings and tent fabrics we prefer to use plain weave fabrics of cotton, nylon or other synthetic fabrics. Light weight fabrics may be used to advantage.

The fabrics may of course be treated to give them other desirable properties, such as dye acceptance, resistance to ultra-violet light, water repellency, for example treatment with silicones and waxes, flame retardancy and for other special effects.

The latex compositions employed to produce the foam may be prepared from at least two of the following monomers of which at least one is a monomer which contains functional groups capable of crosslinking: (a) a,-ethylenically unsaturated acid which includes acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, aconitic acid, crotonic acid, citraconic acid, maleic acid, fumaric acid, a-chloroacrylic acid, cinnamic acid and mesaconic acid;; (b) monomer of formula

wherein R is hydrogen or alkyl, for example, lower alkyl of from 14 carbon atoms and R' is a straight, branched or cyclic alkyl, alkoxyalkyl or alkylthioalkyl radical having from 1 to 20 carbon atoms, or cycloalkyl having from 5-6 carbon atoms, such as methyl, ethyl, propyl, n-butyl, 2-ethylhexyl, heptyl, hexyl, octyl, 2-methyl-butyl, 1methylbutyl, butoxybutyl, 2-methylpentyl, methoxymethyl, ethoxyethyl, cyclopentyl, cylcohexyl, isobutyl, ethylthioethyl, methylthioethyl, ethylthiopropyl, 6methylnonyl, decyl, dodecyl, tetradecyl and pentadecyl;R' is also ureido, hydroxy lower alkyl of from 1 to 5 carbon atoms such as hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, hydroxypentyl, and the like, 2,3epoxypropyl, amino lower alkyl, mono- or di- lower alkyl or hydroxy lower alkyl substituted amino lower alkyl; (c) monomer of the formula

wherein R2 is hydrogen or methyl and R3 is halo such as chloro; lower alkanoyloxy such as acetoxy, cyano, formyl, phenyl, carbamoyl, N-hydroxymethyl carbamoyl, tolyl, methoxymethyl, 2,4, - diamino - s triazinyl lower alkyl or epoxy and

wherein R4 is hydrogen or methyl; R5 and R6 are lower alkoxy such as methoxy and ethoxy or lower alkanoyloxy such as acetoxy.

Examples of the specific monomers (b), (c) and (d) which may be employed are: methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tertbutyl methacrylate, pentyl methacrylate, isopentyl methacrylate, tert-pentyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylbutyl methacrylate 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate, myristyl methacrylate, cetyl methacrylate, stearyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tertbutyl acrylate, amyl acrylate, isoamyl acrylate, tert-amyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, vinyl acetate, tetradecyl acrylate, acrylamide, pentadecyl acrylate, styrene, pentadecyl methacrylate, vinyl toluene, methacrylamide, N-methylolacrylamide and the like, glycidyl methacrylate, methylaminoethyl methacrylate, tertbutylaminoethyl methacrylate, 6 - (3- butenyl) - 2,4 - diamino - s - triazine, hydroxypropyl methacrylate, hydroxyethyl methacrylate, methacrylonitrile, methoxymethyl methacrylamide, Nmethylol methacrylamide, acrolein, methacrolein, 3,4 - epoxy - I - butene, acrolein diethyl acetal, acrolein dimethyl acetal, allyidene diacetate, methallylidene diacetate, the analogs of the above methacrylic acid derivatives with other unsaturated acids such as acrylic acids and itaconic acid, such acids themselves, dicarboxylic acids such as maleic acid and half esters and half amides thereof, vinyl ethers of glycols such as ethylene glycol are also included.

The crosslinkable addition polymerizable unsaturated monomers may have reactive polar groups selected from -OH, -SH, > NH,

-N=C=O, > CHCN, -CHO, -COOH and

Such groups may be included as are mutually or self-crosslinkable, or separate crosslinking compounds such as triazineformaldehyde resin may be added.

Of course, water-sensitive materials such as isocyanates should not be used in aqueous systems unless they are blocked by reaction with a phenol group which protects the isocyanate groups until subsequent heating or the use of other reaction mechanisms such as the use of calcium, zinc, or tin compound catalyst conventional in the art.

The preferred emulsion copolymers have a molecular weight of from 70,000 and 2,000,000 and preferably 250,000 to 1,000,000 and are made by emulsion copolymerization of the several monomers in the proper proportions. Conventional emulsion polymerization techniques are described in U.S. Pat. Nos. 2,754,280 and 2,795,654. Thus, the monomers may be emulsified with an anionic, a cationic, or a nonionic dispersing agent, about 0.05 to 10 percent thereof ordinarily being used on the weight of the total monomers. The acid monomer and many of the other functional or polar monomers may be soluble in water so that the dispersing agent serves to emulsify the other monomer or monomers.

A polymerization initiator of the free radical type, such as ammonium or potassium persulfate, may be used alone or in conjunction with an accelerator, such as potassium metabisulfite or sodium thiosulfate. Organic peroxides, such as benzoyl peroxide and tert-butyl hydroperoxide are also useful initiators. The initiator and accelerator, commonly referred to as catalyst, may be used in proportions of 0.1 percent to 10 percent each based on the weight of monomers to be copolymerized. The amount, as indicated above, may be adjusted to control the intrinsic viscosity -of the polymer. The temperature may be from room temperature to about 260"C.

The following is a list of some of the copolymers which may be employed in this invention. The copolymers have the following monomer compositions: 96EA/3.5AM/0.5AA; 96EA/4MOA; 94EA/5.5ALACAC/0.5AA; 94.5EA/5HEMA/0.SAA 66EA/32.7MMA; l.3MAA; 83EA/l5MMA/2AA; 83BA/l5AN/lAC/lAA; 65EA/25.5BA/4.5AN/3.5AM/l .51A; 86EA/10AN/4MOA; 83BA/14AN/1Ac/2AA: 96EA/1 Ac/2AA; 68BA/28MMA/2Ac/2AN; 30BA/55EA/l0MMA/3.5AN/0.5Ac/l AA and 45BA/10AN/40EA/4HEMA/1AA.

The definitions of the abbreviations are: EA=ethyl acrylate; BA=butyl acrylate; MMA=methyl methacrylate; AA=acrylic acid; MMA=methacrylic acid; IA=itaconic acid; HEMA=hydroxyethyl methacrylate; AN=acrylonitrile; Ac=acrolein; ALACAC=allyl acetoacetate; MOA=acrylamide N - methylol acrylamide (1:1) and AM=acrylamide.

The use of a water soluble surfactant or a combination of surfactants increases the dispersion of the latex emulsion and acts as a foaming aid and foam stabilizer.

These surfactants include the alkali metal, ammonium or amine salts such as the mono-,di- or triethanol amines of the aliphatic carboxylic acids having from 16 to 20 carbon atoms including oleic acid and stearic acid; for example, sodium potassium or ammonium stearate; sodium, potassium and ammonium oleate.Other surfactants which may be employed together with those described above include the alkali metal salts of aliphatic or alkylaryl sulfonic acids, such as sodium lauryl sulfate and sodium dodecylbenzene sulfonate as well as nonionic surfactants such at the polyethylene oxide condensates of the alkyl phenols or higher fatty alcohols, for example, tert-octylphenol condensed with from 5 to about 40 ethylene oxide units, lauryl alcohol condensed with from 5 to 50 ethylene oxide units or similarly ethylene oxide condensates of long chain mercaptans, fatty acids and amines.

To crosslink the acrolein or methacrolein containing resins, a dibasic amine, for example, diethylene triamine, and hydrazine are employed. The melamine type resins are used to crosslink the polymers containing hydroxy and amino functions. Other crosslinking agents may be employed and said agents are well-known to those skilled in the art.

The latex, when formulated with the foam stabilizer and optionally, suitable pigments, is readily convertible into foamed state. The polymer composition is preferably such that excessive thickening of the formulation is not encountered under the acid or alkaline conditions employed to assure the most efficient operation of the foam stabilizing agent. In addition, the copolymer is preferably such that the crushed foam retains its softness and its flexibility at low temperatures, for example, to a temperature as low as -20"C., and after curing is nontacky. In addition, the foam is resistant to washing in normal detergents used for cleaning of textiles in general and drapery fabrics in particular and is resistant to drycleaning.By providing a foam that is durable to dry-cleaning and to washing the foam is quite useful for textiles which are frequently subjected to dry-cleaning and washing operations.

An important property of the polymer for the foam is the glass transition temperature (Tg) thereof, and consequently the selection of monomers and proportions thereof depends upon their influence on the Tg. The Tg. of the polymer for the foam is suitably between -60"C. and 35"C. and 35"C. "Tg" is a conventional criterion of polymer hardness and is described by Flory, "Principles of Polymer Chemistry" pp. 56 and 57 (1953), Cornell University Press.

While actual measurement of the Tg is preferred, it may be calculated as described by Fox, Bull. Am. Physics Soc.l. 3 p. 123 (1956). Examples of the Tg of homopolymers and the inherent Tg thereof which permits such calculations are as follows: Homopolymer of Tg n-octyl acrylate -80"C.

n-decyl methacrylate -60"C.

2-ethylhexyl acrylate -70"C.

octyl methacrylate -20"C.

.n-tetradecyl methacrylate 90 C.

methyl acrylate 9"C.

.n-tetradecyl acrylate 200C methyl methacrylate 105"C.

acrylic acid 106"C.

These or other monomers should be blended to give the desired Tg of the copolymer. As is known, for a given number of carbon atoms in the alcohol moiety, the extent and type of branching markedly influences the Tg, the straight chain products giving the lower Tg. Most of the esters of acrylic acid or methacrylic acid having a low Tg are well known in the art.

Any of the standard or other useful techniques for applying foam may be employed in this invention.

The latex which is to form the foam is preferably initially foamed to a wet foam density of about .5 to .05 grams per cubic centimeter, and is then applied to the substrate in a thickness of from 10 to 300 mils. The density, of course, will vary with the presence or absence of pigments and fillers and their identity. The foam may then be dried without causing thermosetting, crosslinking or vulcanization for example by heating the foam-coated fabric at a temperature below that which causes thermosetting, crosslinking or vulcanization, for example for from 1 to 10 minutes at a temperature of from 200 to 350 F., followed, preferably after having placed the desired number of foam and fabric layers together, by crushing the layers to a thickness of between 5 percent and 25 percent of the original dry thickness.This will give an approximate crushed foam density of from 0.2 to 3 g./cc.3, and is then followed by curing of the crushed foam. In general, the thickness of the dried foam prior to crushing may be substantially less than that of the wet foam, there at times being some shrinkage. This shrinkage may result in up to 30 percent of the thickness of the wet foam being lost during drying. When we talk about dry or substantially dry we mean that the moisture content of the foam will be from 5 percent to 15 or 20 percent. In some cases, crosslinking may be accomplished by catalysis rather than by the application of heat.

When pigmented compositions are contemplated, examples of the pigments that may be employed include clays, especially of the kaolin type, calcium carbonate, blanc fixe, talc, titanium dioxide colored lakes and toners, ochre, carbon black, graphite,.aluminum powder or flakes, chrome yellow, molybdate orange, toluidine red, copper phthalocyanines, such as the "Monastral" blue and green lakes. If dyed compositions are required, examples of dyes for acrylic film and foam include basic and dispersed dyes. Other composites could be made dyeable, if they are not already inherently so, through the use of additives such as methyl cellulose, hydroxyl ethyl cellulose, and the like. Other dyes which could be used include acid dyes, vat dyes, direct dyes and fiber reactive dyes.

In one embodiment of the invention there is provided a process for the production of a laminate according to the invention which comprises forming, on a fabric, a layer of foam of polymer latex, drying the foam to such a moisture content as at least to stabilize the foam, laying a fabric on the foam and subjecting the superimposed layers to heat and pressure to crush and cure the foam.

The laminates may be prepared by applying pressures up to 300 psi. Preferred ranges are 10 to 300 psi, preferably 50 to 150 psi. Temperatures may be from 150 to 300"C. and most preferably 200 to 2500 C.

For a description of suitable conventional foaming procedures and foam stabilizers and foaming agents, reference may be made to Madge, E. W., "Latex Foam Rubber", John Wiley and Sons, New York (1962) and Rogers, T. H. "Plastic Foams", Paper, Reg.

Tech, Conf., Palisades Sect., Soc, Plastics Engrs., New York, November 1964. Most commonly used stabilizers and foaming agents are the alkali metal, ammonia, and amine soaps of saturated or unsaturated acids having, for example, from about 12 to about 22 carbon atoms. Examples of suitable soaps include tallow soaps and coconut oil soaps, preferably the volatile amine or ammonia soaps, so that the volatile portion is vaporized from the foam. Other useful foaming/foam-stabilizing agents include lauryl sulfate-lauryl alcohol, lauryl sulfate-lauric acid, sodium lauryl sulfate.

Some preferred embodiments of the invention will now be described in the following Examples, which are given for the purposes of illustration only and in which all - parts and percentages are by weight unless otherwise specified.

EXAMPLE I An emulsion copolymer dispersion prepared from 25.5 parts of butyl acrylate, 65 parts of ethyl acrylate, 4.5 parts of acrylonitrile and 3.5 parts of acrylamide is formulated in-a ratio of 100 to 7.5 with 5.25 parts of water, 5 parts of 25% ammonium hydroxide, 10 parts of 33% ammonium stearate and 5.62 parts of Aerotex M-3 melamine-formaldehyde resin. The ingredients are mixed and foamed in a kitchen aid mixer (Model C) to a wet density of about 0.2 grams per c.c. The foam is then applied to a cotton fabric at a thickness of 30 mil. (wet) and then dried for three minutes at 1200C. The dried foam coated cotton is then covered by another layer of cotton. The laminate is then subjected to a pressure of about 100 p.s.i.

for three seconds at 1500C. The composite is then given a final cure at 1500C. for five minutes. The product obtained has a soft hand with textile feel and is impermeable to water under 1 metre hydrostatic pressure.

EXAMPLE II Example I is repeated except that the composition of the copolymer is 48.25% ethyl acrylate, 48.25% butyl acrylate, 3% methylolacrylamide/ - methacrylamide solution and 0.5% itaconic acid and a polyester fabric is used instead of the cotton fabric. An excellent abrasion resistant waterproof laminate is obtained.

EXAMPLE III Example I is repeated except that 30 parts of clay are added to the foam-forming formulation and one of the fabric layers is a layer of nylon fabric. An excellent result is obtained, the laminate being waterproof and having one abrasion resistant nylon face and a "sweat resistant" cotton face of textile hand.

EXAMPLE IV Example I is repeated except that the copolymer used is a copolymer of 86 parts ethyl acrylate, 10 parts acrylamide and 4 parts methylolacrylamide/acrylamide solution and the fabric layers are layers of rayon fabric. An excellent waterproof laminate of textile-like hand is obtained.

WHAT WE CLAIM IS: 1. A waterproof (as hereinbefore defined) laminate of alternate fabric (as hereinbefore defined) and crushed, collapsed foam layers made by crushing and curing a laminate of alternate layers of fabric and stable uncured foam foamed on the fabric layer(s) and in which the outer layers are layers of fabric.

2. A laminate as claimed in Claim 1 wherein the fabric is of at least one of cotton, polyester, nylon and rayon.

3. A laminate as claimed in Claim 1 or 2 wherein one outer layer is of an abrasionresistant hydrophobic textile and the other outer layer is of a hydrophilic material.

4. A laminate as claimed in any of Claims 1 to 3 wherein the foam comprises polymer of a mixture of at least two of the following monomers, of which at least one is a monomer which contains functional groups capable of crosslinking (a) ct,-ethylenically unsaturated acid, (b) monomer of the formula

wherein R is hydrogen or alkyl and R' is a straight, branched or cyclic alkyl, alkoxyalkyl or alkyl thioalkyl radical and (c) monomer of the formula

wherein R2 is hydrogen or methyl. and R3 is halo, alkanoyloxy, cyano, phenyl, formyl, carbamoyl, epoxy, N-hydroxy methylcarbamoyl, tolyl, methoxy methyl, 2,4 - diamino - s - triazinyl lower alkyl or (d) monomer of the formula

wherein R4 is hydrogen or methyl; R5 and R6 are lower alkoxy or lower alkanoyloxy.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Tech, Conf., Palisades Sect., Soc, Plastics Engrs., New York, November 1964. Most commonly used stabilizers and foaming agents are the alkali metal, ammonia, and amine soaps of saturated or unsaturated acids having, for example, from about 12 to about 22 carbon atoms. Examples of suitable soaps include tallow soaps and coconut oil soaps, preferably the volatile amine or ammonia soaps, so that the volatile portion is vaporized from the foam. Other useful foaming/foam-stabilizing agents include lauryl sulfate-lauryl alcohol, lauryl sulfate-lauric acid, sodium lauryl sulfate. Some preferred embodiments of the invention will now be described in the following Examples, which are given for the purposes of illustration only and in which all - parts and percentages are by weight unless otherwise specified. EXAMPLE I An emulsion copolymer dispersion prepared from 25.5 parts of butyl acrylate, 65 parts of ethyl acrylate, 4.5 parts of acrylonitrile and 3.5 parts of acrylamide is formulated in-a ratio of 100 to 7.5 with 5.25 parts of water, 5 parts of 25% ammonium hydroxide, 10 parts of 33% ammonium stearate and 5.62 parts of Aerotex M-3 melamine-formaldehyde resin. The ingredients are mixed and foamed in a kitchen aid mixer (Model C) to a wet density of about 0.2 grams per c.c. The foam is then applied to a cotton fabric at a thickness of 30 mil. (wet) and then dried for three minutes at 1200C. The dried foam coated cotton is then covered by another layer of cotton. The laminate is then subjected to a pressure of about 100 p.s.i. for three seconds at 1500C. The composite is then given a final cure at 1500C. for five minutes. The product obtained has a soft hand with textile feel and is impermeable to water under 1 metre hydrostatic pressure. EXAMPLE II Example I is repeated except that the composition of the copolymer is 48.25% ethyl acrylate, 48.25% butyl acrylate, 3% methylolacrylamide/ - methacrylamide solution and 0.5% itaconic acid and a polyester fabric is used instead of the cotton fabric. An excellent abrasion resistant waterproof laminate is obtained. EXAMPLE III Example I is repeated except that 30 parts of clay are added to the foam-forming formulation and one of the fabric layers is a layer of nylon fabric. An excellent result is obtained, the laminate being waterproof and having one abrasion resistant nylon face and a "sweat resistant" cotton face of textile hand. EXAMPLE IV Example I is repeated except that the copolymer used is a copolymer of 86 parts ethyl acrylate, 10 parts acrylamide and 4 parts methylolacrylamide/acrylamide solution and the fabric layers are layers of rayon fabric. An excellent waterproof laminate of textile-like hand is obtained. WHAT WE CLAIM IS:

1. A waterproof (as hereinbefore defined) laminate of alternate fabric (as hereinbefore defined) and crushed, collapsed foam layers made by crushing and curing a laminate of alternate layers of fabric and stable uncured foam foamed on the fabric layer(s) and in which the outer layers are layers of fabric.

5. A laminate as claimed in Claim 4

wherein the foam comprises polymer of a mixture of (a) at least one C1-C4 alkyl acrylate; (b) at least one of: acrylamide, methacrylamide, N-methylol acrylamide and N-methylol methacrylamide; and optionally, (c) at least one of: acylic acid, methacrylic acid, itaconic acid, acrylonitrile and methacrylonitrile.

6. A laminate as claimed in Claim 1 substantially as described in any of the foregoing examples.

7. A process for the production of a laminate according to claim 1 which comprises forming, on a fabric, a layer of foam of polymer latex, drying the foam to such a moisture content as at least to stabilize the foam, laying a fabric on the foam and subjecting the superimposed layers to heat and pressure to crush and cure the foam.

8. A process as claimed in Claim 7 in which the superimposed layers are subjected to a pressure of from 10 to 300 p.s.i. at a temperature of from 150 to 3000C.