GB2157296A - Latex compositions for impregnating non-woven webs - Google Patents

Abstract

Non-woven webs are impregnated with 15-60wt% of a composition comprising a latex containing 30-65wt% of one of three defined types of copolymer each containing units of a carboxylic acid or anhydride monomer, the latex being neutralised to pH5-9 by an alkali metal base. A copolymer of styrene/butadiene/acrylic acid is used in examples. The composition may also contain a latent acid, e.g. NH4Cl.

Description

SPECIFICATION Non-woven webs The present invention pertains to non-woven products of natural or synthetic fibers having good heat stability, good wet strength and a low amount of crosslinking agents such as urea-formaldehyde or N-methylolacrylamide.

Such non-woven webs include a large number of products from papers of natural orsyntheticfibers to loose webs of cellulose or synthetic fibers including synthetic organic fibers such as rayon, polyesters, or nylon and synthetic inorganic fibers such as glass. Non-woven webs may be wet laid, carded or air laid. The fibers are boundtogetherwith a bonding agent which may be a naturally occurring binder such as starch or protein our a synthetic polymer.

There has been an increasing use of non-woven products in our society. Non-wovens of natural or synthetic organic fibers are used for wiping cloths, disposable table cloths, disposable clothing such as lab coats, diapers, surgical drapes and disposable bedding. In these applications there is a growing trend to reduce or eliminate crosslinking agents which may irritate the skin. Such crosslinking agents tend to enhance the wet tensile strength ofthe web when it is being impregnated with the binder. Non-wovens of inorganic fibers such as glass are used to produce webs which may be used to make shingles or road underlay material.

In the past one of the major synthetic binders for non-wovens has been acrylate latices. These latices contained polymers which have a low level of unsaturation and are more stable to heat and light degradation than binders containing conjugated diolefins. Acrylic binders tend to be relatively expensive and this contributesto the cost ofthe finished web. In some instances antioxidants when used may be incompatible with inks and dyes intended to be used on the web as the antioxidant may interfere with the curing of the ink. It would be desirable to find a low cost method of providing a non-woven web having good heat and light stability.The heat aging properties of the compounds of the present invention, particularly those based on carboxylated SBR latices, or vinyl acetate type latices suggest that such compounds could be utilized as low cost paints.

Typical of the current state of the art of non-woven webs are: United States Patent4,356,229 issued Oct.26, 1982, assigned to Rohm and Haas Company; European Patent Application 0071 932 published 16.02.83 in the name ofthe B.F. Goodrich Company; European Patent Application 0012032 published 11.06.78 in the name of Rohm and Haas Company; and United States Patent 4,268,546 issued May 19, 1981, assigned to The Dow Chemical Company. These patents illustrate the current trend in the art to use acrylate polymers in manufacturing non-woven webs.

Much of the work done with the heat stability of polymers has been based on polyvinyl chloride. A very good discussion ofthe current state oftechnology of heat stabilizers appears in Chapters 8 and 9 of Encyclopedia of PVC, Vol. 1, edited by Leonard I. Nass, Marcel Dekker Inc. 1976. This text shows at page 298 that sodium and potassium oxides or hydroxides are not considered heat and light stabilizers.

British Patent Specification 848,808 teaches the use of latex in manufacturing paper. The British patent disclosesthatthe latex may be neutralized with a fixed alkali such as NaOH subsequent to polymerization. The patent teaches that during the curing operation the alkali ion must be replaced with a polyvalent ion to crosslink the polymer, This is not required nor desirable in the present case.

The present invention provides a method of impregnating a non-woven web comprising natural fibers and/or synthetic fibers, said method comprising impregnating the web with about 15 to about 60 weight %.

based on the dry weight of the web, with a composition comprising a latex containing about 30 to about 65 weight % of a polymer formed by polymerizing a monomeric mixture selected from: (A)(i) about 30 to about 70 weight % of a Cs-12 vinyl aromatic monomer which may be unsubstituted or substituted by a CiA alkyl or alkanol radical or a chlorine or bromine atom; (ii) about 70 to about 30 weight % of a C4-s conjugated diolefin; (iii) about 0.Sto about8.Oweight% ofa C.ethyIenicaIly unsaturated carboxylicacid oran anhydrideofa Cs ethylenically unsaturated dicarboxylic acid; (B)(i) about 50.0 to about 99.5 weight % of a Ci-s alkyl or alkanol ester of acrylic or methacrylic acid or a mixture thereof;; (ii) about 30 to about 50 weight % of a C8-12 vinyl aromatic monomer, methyl methacrylate, a C2-4 alkenyl nitrile or a mixture thereof; (iii) about 0.5 to about 20.0 weight % of a C3-9 ethylenically unsaturated carboxylic acid, or an anhydride of a C49 ethylenically unsaturated dicarboxylic acid; and (C)(i) about 60.0 to about 99.5 weight % of a Ci-8 alkyl or alkanol ester of a Cos12 ethylenically unsaturated carboxylic acid or a C28 alkenyl or alkenol ester of a C1-12 saturated carboxylic acid; (ii) about 0.5to about 40.0 weight ofa C3-9 ethylenically unsaturated carboxylic acid or an anhydride of a C49 ethylenically unsaturated dicarboxylic acid; and wherein said latex contains sufficient alkali metal base to provide a pH ofabout 5to about 9; and wherein said method comprises curing the impregnated web.

The present invention also provides webs made by its said method, and said composition used therein to bind the web. The composition may be used as a basis for paint.

In some examples, the invention's said method is utilised with acrylic, acrylate, carboxylated styrene butadiene or vinyl acetate latices. The latices may comprise a polymer formed by polymerizing about 50.0 to about 99.5 weight% of a C1-salkyl or alkanol ester of acrylic or methacrylic acid or a mixture thereof, about 30to about 50 weight% of Cs-izvinyl aromatic monomer or methyl methacrylate, ora Cz4alkenyl nitrile, and about 0.5 to about 20.0 of a C3.9 ethylenically unsaturated carboxylic acid.

Some acrylate esters are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, pentyl acrylate, pentyl methacrylate, hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, octyl acrylate, octyl methacrylate, ethyl hexyl acrylate, ethyl hexyl methacrylate, hydroxylethyl acrylate, and hydroxylethyl methacrylate.

Some vinyl aromatic monomers are styrene, a-methyl styrene, p-methyl styrene, and di-vinyl benzene.

Some ethylenically unsaturated acids are ethylenically unsaturated mono- and di- carboxylic acids containing up to about 9 carbon atoms. Some acids are acrylic acid, methacrylic acid, fumaric acid, itaconic acid, butenoic acid, pentenoic acid, hexenoic acid, heptenoic acid and octenoic acid.

In another example, said method can use carboxylated styrene butadiene latices which are made by polymerizing: (i) about 42 to about 68, e.g. about 55 to about 65 weight % of a Cs-X2 vinyl aromatic monomer which may be unsubstituted or substituted by a CiA alkyl or alkanol radical or a chlorine or bromine atom; (ii) about 20 to about 58, e.g. about 35 to about 45, weight % of a C4-8 conjugated diolefin, preferably butadiene or isoprene; and (iii) about 0.5 to about 8.0 parts by weight, e.g. about 0.5 to about 5.0 weight %, of a C3-9 ethylenically unsaturated acid or an anhydride of a C4.9 ethylenically unsaturated dicarboxylic acid.

Some Cs-12 vinyl aromatic monomers are those referred to previously and chlorostyrene, bromostyrene, and p-t-butyl styrene.

Some C3-s ethylenically unsaturated monocarboxylic acids are acrylic acid, methacrylic acid, butenoic acid, pentenoic acid, hexenoic acid, heptenoic acid, octenoic acid, and cinnamic acid. Anhyxdrides of C49 ethylenically unsaturated acids can be fumaric anhydride and itaconic an hydride.

Vinyl acetate and acrylate type latices can be from a monomeric mixture comprising: (i) from about 60 to about 99.5 weight per cent of a C1-s alkyl or alkanol ester of a C3-12 ethylenically unsaturated acid or a C2-8 alkenyl or alkenol ester of a C1-12 saturated carboxylic acid; (ii) from about 0.5 to about 40 weight per cent of a C3-s ethylenically unsaturated carboxylic acid or an an hydroxide of a C49 ethylenically unsaturated dicarboxylic acid; optionally such a monomeric mixture may include up to about 40 weight per cent of a C2-4 mono-olefin.

Some C2-s alkenyl or alkenol esters of C1-12 saturated acids are homologues of the alkyl or alkanol esters of acrylic or methacrylic acid described above. C2-s alkenyl esters of C1-12 carboxylic acids can be vinyl acetate and its higher homologues. When the alkenyl radical contains a hydroxyl group, the ester is a C2-8 alkenol ester of the saturated acid.

The process for polymerizing such acids is well known and does not form part of this invention. Such processes are well known to those skilled in the art and involve the use of conventional catalysts and initiators, surfactants, electrolytes and molecular weight control agents (chain transfer agents). Generally the latex will have about 30 to about 65% by weight of polymeric solids, preferably about 45 to about 60% by weight.

Generally, in the polymerization of polymers containing carboxylic acid monomers the latex is neutralized, usually after the polymerization reaction or after stripping the residual unpolymerized monomer from the latex. In the prior art the latex is neutralized with a fugitive orvolatile base such as ammonium hydroxide, or a lower alkyl amine. According to the present invention the carboxylic acid groups in the polymer must be neutralized with an alkali metal base, preferably a hydroxide of sodium or potassium.

To obtain the benefits of the present invention, it is important that the polymer in its end use by neutralized with a fixed alkali. It is bestto neutralizethe latex directly with a fixed alkali. However, in applications where the latex is heated, it is possible to initially neutralize the latex with a fugitive base, then add sufficient fixed alkali to neutralize the carboxyl group in the polymer after the fugitive base is driven off. As used in this specification, the phrase "containing sufficient alkali metal base to provide a pH from about 5 to 9" includes a latex which may have been originally neutralized with a fugitive base and then had sufficient alkali metal base added to itto keep the latex at the required pH as the fugitive base is driven off.

Preferably, the latex is adjusted to a pH of from about 5 to about 9 with the alkali metal base. Preferably the latex is neutralized to a pH of about 6.5to about 8.5, e.g.the pH is in the range from about 7 to about 8. The most preferred pH is about 7.5.

In accordance with a preferred embodiment of the present invention the latex is then compounded with latent acid(s) as about 0.25 to about 3.0 parts by weight per 100 parts by weight of polymer. As used in this specification the term latent acid means a chemical which when dissolved in an aqueous system and subjected to heat and drying conditions will generate an acid. Preferred latent acids are the salts of a volatile base and a strong acid. Preferred volatile bases are ammonium hydroxide and CiA alkyl or alkanol amines. Preferred strong acids are hydrochloric acid, nitric acid, sulphuric and sulphonic acids. Some latent acids are ammonium chloride, ammonium nitrate, ammonium sulphate, chlorides, nitrates and sulphates of CiA alkyl or alkanol amines, e.g. hydrochlorides or hydrobromides, or amine derivatives of p-toluene sulphonic acid.

The latent acid may be about0.5to about 1.5 orabout3.0 parts per100 parts of latex solids. There is littleto gain by using in excess of 3 parts by weight per 100 parts by weight of latex solids. In fact, excess latent acid may harm the non-woven web and be detrimental to the heat and ageing properties of the web. The latent acid is preferably about 0.5 to about 1.0 or about 1.5 part by weight per 100 parts by weight of latex solids, preferably about 1 part per 100 parts by weight of latex solids.

The non-woven web is then impregnated with a compound based on the latex. It is not necessary to add conventional heat stabilizers to this compound unless exceptional heat stability is required. It should also be recognized that in some cases, heat and light stabilizers colour the web and lower the tensile strength of the web. Takeup is e.g. about 15 to about 60% by weight of the solids in the latex based on the weight of the dry web. A preferred takeup is from about 30 to about 50% by weight.

Compounding and impregnation techniques are well known and do not form part ofthis invention. The web may pass through an impregnation bath and then through squeeze rollers to control the pickup of latex from the web. The web may be contacted with a roller coater or may be sprayed with the compound.

Webs which may be used in the present invention may be made of natural or synthetic fiber or a mixture thereof. If a mixture is used it comprises e.g. about 70 to about 30 weight % of natural fibers and about 30 to about 70 weight % synthetic fibres. Entirely synthetic web is e.g. fiber such as a polyester or polyamide (e.g.

nylon), or synthetic inorganic fiber e.g. glass. The non-woven web may be carded or wet or air laid. The web may weigh about 5to about 130 (e.g. about 10to about 25) g/yd2, about 5.9 to about 155.5 (e.g. about 11 .96 to about 29.9) git2.

The following examples illustrate and do not limit the present invention. In the examples, unless otherwise stated, units are in parts by weight.

A latex was prepared by polymerizing a monomeric mixture comprising about 50 weight % styrene, about 47weight% butadiene, and about3weight% acrylic acid. Subsequentto polymerization, a portion ofthe latex was neutralized with KOH and a portion neutralized with NH40H. A polyester web about 12 g/yd2 (about 14.3 g/m2) impregnated with the compound and dried at about 82.2"then cured for a shorttime at about 176.7"C.

The resulting web was subjected to heat aging at about 176.7"C for a time upto 10 min. and measurements of wettensile strength and elongation at breakweretaken. The heat discolouration oftheweb will increase with prolonged heating, and thus, the results at over 10 minutes, at about 176.7"C, were not measured. Reflectance ofthe samples multiplied by 1000 was also recorded. The results are recorded in Table I (metric in Table IA).

In Table I CMD means cross machine direction. Clearly best protection against heat aging occurs with KOH at pH's from 6 to 9. The best heat aging results are in the pH range of 7 to 8. The data also show that the tensile strength of the web is below the control, neutralized with NH40H.

The experiment was repeated with the following changes. The latex was neutralized to a pH of 7.75 with KOH. To the latex various amounts of NH4CI were added. The results are recorded in Table II (metric in Table IIA).

In Table II phls is parts by weight per 100 parts by weight latex solids. Table II clearly showsthat an improved balance of wet tensile strength, elongation at break, and resistance to heat ageing is obtained by using as a binder a latex containing both a fixed alkali and a latent acid.

A commercially available acrylate (Rhoplex 1715 - trademark of Rohm & Haas Company) was tested for heat stability when neutralized with KOH or NH40H. Aweb about 12 g/yd2 (about 14.3g/m2) was used. Results are set forth in Table III (metric in Table IIIA).

In the experiments, the lower the reflectance reading, the less discoloration in the sample.

TABLE I Sample 1 2 3 4 5 6 7 KOH, pH = 5.0 6.0 7.0 8.0 9.0 10.0 Control NH40H, pH = - - - - - - 9.0 Web o Polyester 12.5 g/yd2 Pick-up, % 47.5 56.5 63.5 59.4 55.2 63.9 58.3 Weight - g/yd2 18.4 19.6 20.4 19.9 19.4 20.5 19.8 Tensile Strength CMD-Wet Ib./in. 0.64 0.68 0.48 0.36 0.29 0.27 0.63 Elongation - % 52.6 78.6 75.3 34.5 23.2 26.0 69.2 Heat Aging (z 350"F (Reflectance) Minutes-0 25 25 13 6 13 13 6 3 82 25 12 12 6 12 100 6 167 51 25 19 19 37 268 10 301 164 25 25 31 43 369 TABLE II Sample 1 2 3 4 5 6 KOH pH = 7.75 NH40H pH = - - - - - 9.0 NH4CI phls 0 0.25 0.5 1.0 1.5 Nil Web Polyester q, 12.5 g/yd2 Pick-up % 49.7 53.4 61.2 57.8 55.1 63.0 Weight g/yd2 18.7 19.2 20.2 19.7 19.4 20.4 CMD-Wet Ib./in. 0.34 0.45 0.57 0.65 0.51 0.64 Elongation - % 39.1 37.7 75.6 88.8 80.9 65.6 Heat Aging " 350 F (Reflectance) atMinutes-10 44 50 50 62 75 328 TABLE Ill Sample 10 11 12 13 14 15 16 NH3 KOH pH 6.7 8.5 10.0 11.0 8.5 10.0 11.0 Web - (B) Pick-up % 52.0 52.4 50.3 50.4 50.6 55.1 55.6 CMD-lb/in - Dry 1.29 1.12 1.12 1.04 1.02 1.20 1.37 Wet 0.81 0.72 0.71 0.67 0.44 0.09 0.07 Elongation %- Dry 48.9 50.5 43.8 43.4 39.9 36.5 46.7 Wet 41.0 40.9 38.2 33.0 19.2 15.5 18.5 Heat Aging f o 350 F (Reflectance) Minutes 0 18 24 18 18 12 18 24 1 24 24 30 24 24 24 36 3 109 108 88 81 18 24 30 4 189 158 185 157 18 6* 24 6 221 275 270 221 18 30 26 UV-Aging " 140 F (Reflectance) Hours 24 19 19 25 18 12 12 12 48 19 25 18 18 31 24 25 72 25 25 19 19 12 12 18 Anomalous result A sample of latex was prepared as described in Example 1 exceptthatthe latex was neutralized to a pH of 8.1 with NH4OH. Two samples ofthis latex were then adjusted to a pH of 10with NH40H in one case and KOH in the other case. NH4CI was added to a portion of the latex containing KOH in an amount of 1.5 parts by weight per 100 parts of polymers An Owens/Corning 670M (Trademark) 1.27cm glass web weight about 83.7g/m2) was impregnated with binder and the sampie dried and cured. The dried sheets were then subjected to a heat ageing test and the reflectance multiplied by 1000 was recorded. The results are shown in Table IV.

TABLE IV Minutes at 204.4 C 1.5 1.5 3.0 5.0 7.0 10.0 A- NH40H 57 63 83 117 185 200 B-KOH 51 44 57 50 57 63 C - KOH + NH4CI 51 50 57 76 76 83 The wet and dry tensile strength of the webs were then measured at various cure times at 204.4*C. Results are recorded in Table V (metric in Table VA).

TABLE V Tensile Strength Ib./in.

Time NH40H KOH KOH + NH4CI Dry Wet Dry Wet Dry Wet 0.5 18.8 5.0 18.4 5.0 14.8 2.8 5.0 15.2 6.2 20.0 9.2 14.0 6.8 10.0 18.8 7.8 19.6 9.0 20.8 7.8 TABLE IA Sample 1 2 3 4 5 6 7 KOH, pH = 5.0 6.0 7.0 8.0 9.0 10.0 Control NH4OH, pH = - - - - - - 9.0 Web qt Polyester 14.9g/m2 Pick-up, % 47.5 56.5 63.5 59.4 55.2 63.9 58.3 Weight - g/m2 22.0 23.4 24.4 23.8 23.2 24.5 23.7 Tensile Strength CMD-Wet Kg/cm 0.11 0.12 0.09 0.06 0.05 0.05 0.11 Elongation - % 52.6 78.6 75.3 34.5 23.2 26.0 69.2 Heat Aging (, 176.7"C (Reflectance) Minutes - 0 25 25 13 6 13 13 6 3 82 25 12 12 6 12 100 6 167 51 25 19 19 37 268 10 301 164 25 25 31 43 369 TABLE 11A Sample 1 2 3 4 5 6 KOH pH = 7.75 NH40H pH = - - - - - 9.0 NH4CI phls 0 0.25 0.5 1.0 1.5 Nil Web Polyester rte 14.9g/m2 Pick-up % 49.7 53.4 61.2 57.8 55.1 63.0 Weight g/m2 23.4 23.0 24.2 23.6 23.2 24.4 CMD-Wet Kg/cm 0.06 0.08 0.10 0.12 0.09 0.11 Elongation - % 39.1 37.7 75.6 88.8 80.9 65.6 Heat aging rce 176.6 C at Minutes - 10 44 50 50 62 75 328 TABLE I1IA Sample 10 11 12 13 14 15 16 NHa KOH pH 6.7 8.5 10.0 11.0 8.5 10.0 11.0 Web - (B) Pick-up % 52.0 52.4 50.3 50.4 50.6 55.1 55.6 CMD-Kg/cm Dry 0.23 0.20 0.20 0.19 0.18 0.21 0.25 -Wet 0.14 0.13 0.13 0.12 0.08 0.02 0.12 Elongation %-Dry 48.9 50.5 43.8 43.4 39.9 36.5 46.7 -Wet 41.0 40.9 38.2 33.0 19.2 15.5 18.5 Heat Aging t(l 176.7"C (Reflectance) Minutes 0 18 24 18 18 12 18 24 1 24 24 30 24 24 24 36 3 109 108 88 81 18 24 30 4 189 158 185 157 18 6- 24 6 221 275 270 221 18 30 26 UV-Aging ', 60.0"C (Reflectance) Hours 24 19 19 25 18 12 12 12 48 19 25 18 18 31 24 25 72 25 25 19 19 12 12 18 Anomalous result TABLE VA Tensile Strength Kg/cm Time NH40H KOH KOH + NH4CI Dry Wet Dry Wet Dry Wet 0.5 3.4 0.90 3.3 0.9 2.6 0.5 5.0 2.7 1.1 3.6 1.6 2.5 1.2 10.0 3.4 1.4 3.5 1.6 3.7 1.4 The resistance to heat and light aging of webs of natural or synthetic fibers is improved by using as a binder a composition comprising a latex of a polymer containing a carboxylic acid functional group, which has been neutralized with a fixed alkali, preferably in conjunction with a latent acid.

Various conversions have been made above to give metric equivalents, e.g. an Owens/Corning 670M glass web of 70 g/yd2 corresponds to 83.7 g/m2.

The expression "parts by weight" includes e.g. "weight %".

Claims (17)

1. A method of impregnating a non-woven web comprising natural fibers and/or synthetic fibers, said method comprising impregnating the web with about 15 to about 60 weight %, based on the dry weight ofthe web, with a composition comprising a latex containing about 30 to about 65 weight % of a polymer formed by polymerizing a monomeric mixture selected from:: (A)(i) about 30 to about 70 weight % of a C8-12 vinyl aromatic monomer which may be unsubstituted or substituted by a CiA alkyl or alkanol radical or a chlorine or bromine atom; (ii) about 70 to about 30 weight % of a C4.s conjugated diolefin; (iii) about 0.5to about 8.0 weight % of a C3 9 ethylenically unsaturated carboxylic acid or an an hydroxide of a C4-9 ethylenically unsaturated dica rboxylic acid; (B)(i) about 50.0 to about 99.5 weight % of a C1-8 alkyl or alkanol ester of acrylic or methacrylic acid or a mixture thereof; (ii) about 30 to about 50 weight % of a C8-12 vinyl aromatic monomer, methyl methacrylate, a C2A alkenyl nitrile or a mixture thereof;; (iii) about 0.5 to about 20.0 weight % of a C3-9 ethylenically unsaturated caboxylic acid, or an anhydride of a Cs ethylenically unsaturated dicarboxylic acid; and (C)(i) about 60.0 to about 99.5 weight % of a C1-8 alkyl or alkanol ester of a C3-12 ethylenically unsaturated carboxylic acid or a C2-8 alkenyl or alkenol ester of a C1-12 saturated carboxylic acid; (ii) about 0.5 to about 40.0 weight % of a C3-9 ethylenically unsaturated carboxylic acid or an an hydride of a C4-9 ethylenically unsaturated dicarboxylic acid; and wherein said latex contains sufficient alkali metal base to provide a pH of about 5 to about 9; and wherein said method comprises curing the impregnated web.

2. A method as claimed in claim 1, wherein said impregnating comprises impregnating the web with about 30 to about 50 weight %, based on the dry weight of the web, of said composition.

3. A method as claimed in claim 1 or 2, wherein said latex contains per 100 parts by weight of polymer in said latex, about 0.25 to about 3.0 parts by weight of latent acid(s).

4. A method as claimed in claim 3, wherein said amount of latent acid(s) is about 0.5 to about 1.5 parts by weight per 100 parts by weight of polymer in said latex.

5. A method as claimed in claim 3 or 4. wherein said latent acid(s) is selected from ammonium chloride, ammonium nitrate, ammonium sulphate, chlorides, nitrates and sulphates of CiA alkyl or alkanol amines.

6. A method as claimed in claim 3 or 4, wherein said latent acid(s) is selected from ammonium chloride, ammonium nitrate, and ammonium sulphate.

7. A method as claimed in any one of claims 1 to 6, wherein said pH is about 6.5 to about 8.5.

8. A method as claimed in any one of claims 1 to 7, wherein said web is a polyester, polyamide or glass web, and weighs about 5.9 to about 155.5 g/m2.

9. A method as claimed in any one of claims 1 to 8, wherein said polymer has been formed by polymerizing a monomeric mixture comprising: (i) about 50.0 to about99.sweight% of a Cl-8 alkyl oralkanol ester of acrylic or methacrylic acid or a mixture thereof; (ii) about 30 to about 50 weight % of a Cs-12 vinyl aromatic monomer or methyl methacrylate, or a C2-4 alkenyl nitrile, or a mixture thereof; and (iii) about 0.5 to about 20.0 weight % of a C3-9 ethylenically unsaturated acid, or an anhydride of a C4-9 ethylenically unsaturated dicarboxylic acid.

10. A method as claimed in any one of claims 1 to 8, wherein said polymer has been formed by polymerizing a monomeric mixture comprising: (i) about 42 to about 68 weight % of a C8-12 vinyl aromatic monomer which may be unsubstituted or substituted by a CiA alkyl or alkanol radical or a chlorine or bromine atom; (ii) about 30 to about 58 weight % of a C4A conjugated diolefin; (iii) about 0.5 to about 8.0 weight% of a C3-sethylenically unsaturated carboxylic acid or an anhydride of a C4-9 ethylenically unsaturated dicarboxylic acid.

11. A method as claimed in claim 10, wherein said polymer has been formed by polymerizing a monomeric mixture comprising: (i) about 55 to about 65 weight % of styrene, (x - methyl styrene, or p-methyl styrene; (ii) about 35 to about 45 weight % of a butadiene or isoprene; (iii) about 0.5 to about 5.0 weight % of methacrylic or acrylic acid.

12. A method as claimed in any one of claims 1 to 8, wherein said polymer has been formed by polymerizing a monomeric mixture comprising: (i) about 60.0 to about 99.5 weight % of a Ci alkyl or alkanol ester of a C3-12 ethylenically unsaturated carboxylic acid or a C2-s alkenyl or alkenol ester of a C1-12 saturated carboxylic acid; (ii) about 0.5 to about40.0 weight % of a C3-9 ethylenically unsaturated carboxylic acid or an anhydride of a C4.9 ethylenically unsaturated dicarboxylic acid.

13. A method as claimed in claim 1, substantially as described in the examples.

14. An impregnated web, when made by a method as claimed in any one of claims 1 to 13.

15. A composition corresponding to said composition recited in claim 1.

16. A composition as claimed in claim 15, when intended for a method as claimed in any one of claims 1 to 13.

17. A composition as claimed in claim 15, when intended for use as a basis for paint.