Moisture-proof, fibrous substrate having adjustable moisture and wet strength, and method for production thereof

Abstract

The present invention relates to a wet strength, fibre-containing substrate having adjustable wet strength and wetness strength, wherein the substrate comprises fibres, at least one binder, at least one amphoteric amine and at least one moistening agent, wherein the at least one binder comprises or consists of at least one polysaccharide having at least one acid group-containing residue, and wherein the at least 1 moistening agent comprises at least 1 organic component selected from the group consisting of aliphatic alcohols, aliphatic ethers, aliphatic esters, monosaccharides, oligosaccharides and mixtures thereof, preferably aliphatic alcohols, aliphatic ethers and mixtures thereof, and also, furthermore, to a method for producing the wet strength, fibre-containing substrate, and to use thereof.

Claims

1. Wet strength, fibre-containing substrate, wherein the substrate comprises fibres, at least 1 binder, a salt or complex of polyvalent metal cation with at least 1 amphoteric amine, which is a compound which may react both as Brønsted acid and as Brønsted base, and at least 1 moistening agent, wherein the at least 1 binder comprises at least 1 polysaccharide having at least 1 acid group-containing residue and wherein the at least 1 moistening agent comprises at least 1 organic component selected from the group consisting of aliphatic alcohols, aliphatic ethers, aliphatic esters, monosaccharides, oligosaccharides and mixtures thereof.

2. Wet strength, fibre-containing substrate according to claim 1, wherein the at least 1 polysaccharide of the at least 1 binder is selected from the group consisting of cellulose, starch, agarose, algin, alginate, chitin, pectin, gum arabic, xanthan gum, guaran and a mixture thereof.

3. Wet strength, fibre-containing substrate according to claim 1, wherein the at least 1 binder is selected from the group consisting of carboxyalkyl celluloses, carboxyalkyl alkyl celluloses, carboxyalkyl hydroxyalkyl celluloses and mixtures thereof, wherein the alkyl residue may be straight-chain or branched, each having 1 to 4 carbon atoms.

4. Wet strength, fibre-containing substrate according to claim 1, wherein the at least one binder comprises an alkali metal salt of carboxymethyl cellulose (CMC) having an average degree of substitution (DS) by carboxymethyl groups, determined in accordance with ASTM D 1439-03/method B, in a range of more than 0.4 to 1.5.

5. Wet strength, fibre-containing substrate according to claim 1, wherein the substrate comprises the at least 1 binder in a proportion in a range of 1% by weight to 35% by weight, based on the total weight of the dry substrate.

6. Wet strength, fibre-containing substrate according to claim 1, wherein the at least 1 amphoteric amine is selected from the group consisting of aminocarboxylic acids having preferably 2 to 36 carbon atoms, which may be unsubstituted or substituted, salts thereof, complexes thereof and mixtures thereof.

7. Wet strength, fibre-containing substrate according to claim 1, wherein the at least 1 amphoteric amine is selected from the group consisting of alanine, arginine, asparagine, aspartic acid, citrulline, cysteine, S-methylcysteine, cystine, creatine, homocysteine, homoserine, norleucine, 2-aminobutanoic acid, 2-amino-3-mercapto-3-methylbutanoic acid, 3-aminobutanoic acid, 2-amino-3,3-dimethylbutanoic acid, 4-aminobutanoic acid, 2-amino-2-methylpropanoic acid, 2-amino-3-cyclohexylpropanoic acid, 3-aminopropanoic acid, 2,3-diaminopropanoic acid, 3-aminohexanoic acid, gamma-carboxyglutamic acid (3-aminopropane-1,1,3-tricarboxylic acid), glutamine, glutamic acid, glycine, histidine, hydroxyproline, p-hydroxyphenylglycine, isoleucine, isovaline, leucine, lysine, methionine, ornithine ((S)-(+)-2,5-diaminopentanoic acid), phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, salts thereof, complexes thereof and mixtures thereof.

8. Wet strength, fibre-containing substrate according to claim 1, wherein the substrate comprises the at least 1 amphoteric amine in a proportion in a range of 0.1% by weight to 30% by weight, based on the total weight of the dry substrate.

9. Wet strength, fibre-containing substrate according to claim 1, wherein the at least 1 moistening agent comprises the at least one organic component in a proportion of at least 5.0% by weight, based on the total weight of the at least 1 moistening agent.

10. Wet strength, fibre-containing substrate according to claim 1, wherein the at least 1 moistening agent comprises at least 1 organic component selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, 2,2-dimethyl-1-propanol, 1-hexanol, ethane-1,2-diol, propane-1,2-diol, propane-1,3-diol, butane-1,2-diol, butane-1,3-diol, butane-1,4-diol, butane-2,3-diol, 1,2,3-propanetriol, 1,2,3,4-butanetetraol, 1,2,6-hexanetriol, 1,2,3,4,5,6-hexanehexol, 2-(2-hydroxyethoxy)ethanol, 2-[2-(2-hydroxyethoxy)ethoxy]ethanol, PEG-4, PEG-6, PEG-7, PEG-8, PEG-9, PEG-10, PEG-12, PEG-14, PEG-16, PEG-18, PEG-20 and mixtures thereof.

11. Wet strength, fibre-containing substrate according to claim 1, wherein the substrate is a fabric.

12. Wet strength, fibre-containing substrate according to claim 1, wherein the at least 1 moistening agent further comprises at least 1 polyvalent metal cation selected from the group consisting of polyvalent ions of the transition metals, polyvalent ions of the metals of the 3rd and 4th main groups of the Periodic Table of the Elements, ions of the alkaline earth metals and mixtures thereof.

13. Wet strength, fibre-containing substrate according to claim 1, wherein the at least 1 moistening agent further comprises at least 1 metal cation selected from the group consisting of Ca.sub.2+, Zn.sub.2+ and mixtures thereof.

14. Method for producing a wet strength, fibre-containing substrate according to claim 1, wherein the method comprises the following step: (a) providing a fibre-containing substrate comprising fibres and the at least 1 binder, wherein furthermore, in and/or after step (a), the at least 1 amphoteric amine and the at least 1 moistening agent are added successively, together or simultaneously.

15. Use of a wet strength, fibre-containing substrate according to claim 1 as a hygiene article or as a wet wipe.

16. The wet strength, fibre containing substrate of claim 1, wherein the at least 1 acid group-containing residue is selected from the group consisting of carboxyl group-containing residues, phosphate-containing residues, phosphonic acid-containing residues and combinations thereof.

Description

INVENTIVE EXAMPLE 1: AIRLAID NONWOVEN WITH CONTROLLABLE DISINTEGRABILITY

(1) For the following experiments, a commercially available airlaid cellulose nonwoven with a total basis weight of around 50 g/m.sup.2 was used, with the designation W4 from ASCUTEC Airlaid-Produktion GmbH & Co KG (Nuremburg, Del.). The paper weights of the respective nonwoven webs were determined prior to use on cut samples measuring 10×10 cm.

(2) Commercially available carboxymethyl celluloses (CMC) were used as binders containing at least one polysaccharide with acid group-containing residue. Rheolon® 30, Rheolon® 300, Rheolon® 500G and Rheolon® 1000G were obtained from Ugur Seluloz Kimya A.S. (Aydin, TR). Calexis® HMB and Finnfix® 700 were obtained from CP Kelco Germany GmbH (Grossenbrode, Del.).

(3) The carboxymethyl celluloses used had different dynamic viscosities. Prior to application of the binder, samples of the particular binder used were taken, and a measurement was made of the dynamic viscosity of a 2% by weight solution of the binder in water at 20° C.

(4) The viscosity of a 2% by weight solution of the corresponding binder in water at 20° C. was determined by means of a Searle rotary viscometer of type Haake® Viscotester® 550 (Thermo Fisher Scientific Inc., Karlsruhe, Del.) with cylinder measuring facility, MV measuring cup, at a rotational speed of 2.55 s.sup.−1. The 2% by weight solution of the corresponding binder in water that was used was prepared by dissolving 2 g of the binder with stirring in 100 g of distilled water at 20° C. in accordance with manufacturer specifications.

(5) The nonwoven webs were each first sprayed on one side with a 5% by weight aqueous dispersion of one of the above-specified binders, containing at least one polysaccharide with acid group-containing residue, the stated percentage being based on the binder content of the dispersion used per 100 g of water. The 2% by weight solution of the corresponding binder in water that was used was prepared with stirring in distilled water in accordance with manufacturer specifications. The particular amount of the binder applied, based on the area of the nonwoven web after drying, is reported in Table 1 (“Amount applied”).

(6) After drying and removal of the binder by condensation at a temperature of 150° C. to 170° C., the nonwoven web produced was rolled up.

(7) This was followed by measurement of the tensile values of the resulting nonwoven webs in the dry state. For this purpose, samples of the resultant nonwoven webs measuring 10×10 cm were measured at room temperature in a tensile test according to DIN 54540-8 by pulling in the machine direction. The tensile values reported below (“Tensile value, dry”) represent the arithmetic mean of 10 measurements in each case. The results are summarized in Table 1.

(8) TABLE-US-00001 TABLE 1 Comparison of the binders used and of the dry strengths achieved therewith Binder Tensile Nonwoven Viscosity Applied amount value, dry No. Type [mPa .Math. s] [g/m.sup.2] [N] 1a Rheolon 30 36 1.75 38.4 1b Rheolon 300 303 1.69 38.7 1c Calexis HMB 520 1.91 67.5 1d Finnfix 700 610 0.98 36.3 1e Finnfix 700 623 1.29 62.5 1f Rheolon 500 G 630 1.42 31.7 1g Rheolon 500 G 660 1.72 43.0 1h Rheolon 1000G 960 1.35 30.6 1i Rheolon 1000G 945 1.54 36.2 1j Rheolon 1000G 1100 1.78 46.5

(9) The tensile values of the resultant nonwoven web were also measured in the wet state. For this purpose, samples of the respectively resultant nonwoven webs measuring 10×10 cm were cut out, after drying and removal of the binder by condensation, and 11 ml of “Lotion 1” per sample were added. The composition of “Lotion 1” was as follows:

(10) TABLE-US-00002 Ingredient Final concentration L-Lysine 5.9% by weight CaCl.sub.2 × 2 H.sub.2O 4.2% by weight 1,2-Propanediol 31.9% by weight Ethanol 3.5% by weight Water 54.5% by weight

(11) The stated % by weight are based in each case on the total weight of the lotion.

(12) Following incubation at room temperature for 60 minutes, the tensile values of the moistened samples were measured at room temperature in a tensile test in analogy to DIN 54540-8 by pulling in machine direction. The tensile values reported below (“Tensile value, wet”) represent the arithmetic mean from 10 measurements in each case.

(13) Furthermore, the dissolution behaviour of the samples, wetted with lotion 1, in distilled water was ascertained. For this purpose, the premoistened samples measuring 10×10 cm were placed into vessels containing 100 ml of distilled water, and then incubated with stirring until the sample was dissolved. Here it was possible to remove only fibres from the vessel, using tweezers. The measurement was conducted in each case at intervals of 5 s. The disintegration times (“Dissolution in water”) reported in Table 2 represent the arithmetic mean from 10 measurements in each case.

(14) TABLE-US-00003 TABLE 2 Comparison of the wet strengths and wetness strengths achieved after wetting with lotion 1 Lotion 1 Nonwoven Tensile value Dissolution in water No. [N] [s] 1a 10 30 1b 15 35 1c 15 50 1d 7 10 1e 11 25 1f 13 20 1g 14 40 1h 11 10 1i 13 40 1j 15.4 45

(15) Increasing application of binder leads to increasing dry strength of the resultant nonwoven material after drying and removal of the binder by condensation. Even small increases in the viscosity and/or in the chain length of the binder used lead to superproportional increases in strength for a comparable applied amount, particularly in the case of low molecular mass carboxymethyl celluloses.

INVENTIVE EXAMPLE 2

(16) The nonwoven webs 1a, 1c, 1e and 1i produced in example 1 were further treated with different lotions having different water contents. For this purpose, samples of the respective nonwoven webs measuring 10×10 cm were cut out, after drying and removal of the binder by condensation, and 11 ml of various lotions 1 to 5 were added per sample. The composition of the lotions 1 to 5 used is shown in Table 3. The % by weight reported refer in each case to the total weight of the lotion.

(17) After incubation at room temperature for 60 minutes, the tensile values of the wetted samples were measured at room temperature in a tensile test in analogy to DIN 54540-8 by pulling in machine direction. The tensile values reported below (“Tensile value, wet”) represent the arithmetic mean from 10 measurements in each case.

(18) TABLE-US-00004 TABLE 3 Wet strengths achieved on reduction of the water content of the lotion Binder Rheolon 1000G Calexis HMB Finnfix 700 Rheolon 30 Applied amount [g/m.sup.2] 1.54 1.91 1.29 1.75 Lotion Composition [% by weight] No. L-Lysine CaCl.sub.2 × 2 H.sub.2O 1,2-Propanediol Ethanol Water Tensile value, wet [N] 5 3.9 2.8 21.3 2.3 69.7 2.5 3.4 2.2 1.2 1 5.9 4.2 31.9 3.5 54.5 13.0 15.7 11.0 10.0 2 5.9 4.7 35.4 3.9 50.1 17.4 16.1 9.8 15.2 3 6.5 5.2 39.0 4.3 45.0 19.0 19.6 14.0 11.0 4 7.1 5.7 42.6 4.7 39.9 18.8 19.1 15.9 15.0

(19) A reduction in the fraction of water in the lotion leads to an increase in the wet strength. The wet strength can be controlled over a wide range by measures including a change in the water content of the lotion.

INVENTIVE EXAMPLE 3

(20) The nonwoven webs 1a and 1e produced in example 1 were further treated with different lotions in which only the amphoteric amine was present in the lotion (Lotion 6) or the amphoteric amine was used as the calcium salt (Lotions 7 and 8). For this purpose, samples of the respective nonwoven webs measuring 10×10 cm were cut out, after drying and removal of the binder by condensation, and 11 ml of various lotions 6 to 8 were added per sample. The composition of the lotions 6 to 8 used is shown in Table 4. The % by weight reported refer in each case to the total weight of the lotion.

(21) Prior to use in lotions 7 and 8, the calcium salt of L-lysine was produced by reacting the amount of L-lysine reported in Table 4 with the amount of CaCl.sub.2×2×H.sub.2O reported in Table 4, in distilled water, and added to the corresponding lotion.

(22) After incubation at room temperature for 60 minutes, the tensile values of the wetted samples were measured at room temperature in a tensile test in analogy to DIN 54540-8 by pulling in machine direction. The tensile values reported below (“Tensile value, wet”) represent the arithmetic mean from 10 measurements in each case.

(23) TABLE-US-00005 TABLE 4 Wet strength values when using lotions 6 to 8 Binders Finnfix 700 Rheolon 30 Applied amount [g/m.sup.2] 1.29 1.75 Lotion Composition [% by weight] Tensile value, wet No. L-Lysine CaCl.sub.2 × 2 H.sub.2O 1,2-Propanediol Ethanol Water [N] 6 10.0 — 34.0 13.0 43.0 9.1 8.2 7 9.4 3.8 42.2 4.7 39.9 17.3 15.0 8 6.5 5.2 39.0 4.3 45.0 19.6 19.0

(24) With a lotion containing only an amphoteric amine and no further polyvalent metal cations, it was also possible to achieve sufficient wet strength. In place of the polyvalent ions, the pH is adjusted using organic or inorganic acids, with the pH used being in a range of 4.0 to 5.5.

(25) When a calcium salt of the corresponding amphoteric amine was used in the lotion (Lotions 7 and 8), very good wet strengths were achieved.

INVENTIVE EXAMPLE 4

(26) The lotions 1 to 8 used contained L-lysine as amphoteric amine. To investigate the effect of other amphoteric amines on the wet strength, further nonwoven webs were produced. For that purpose, a commercially available airlaid cellulosic nonwoven was likewise used, having a total basis weight of around 50 g/m.sup.2, with the designation W4 from ASCUTEC Airlaid-Produktion GmbH & Co KG (Nuremberg, Del.).

(27) The binder used was Rheolon 1000G, which was sprayed onto both sides of the nonwoven web, in the form of a 4% by weight aqueous dispersion of the binder, the stated percentage being based on the binder content of the dispersion used per 1000 g of water. 1.75 g/m.sup.2 of Rheolon 1000G was applied to each of the facing and reverse sides of the nonwoven web. The total application of binder to the nonwoven web was therefore 3.5 g/m.sup.2 of Rheolon 1000G. After drying and removal of the binder by condensation at a temperature of 150° C. to 170° C., the nonwoven produced was rolled up.

(28) This was followed by measurement of the tensile values of the resulting nonwoven webs in the dry state. For this purpose, samples of the resultant nonwoven webs measuring 10×10 cm were measured at room temperature in a tensile test according to DIN 54540-8 by pulling in the machine direction. The tensile values reported below (“Tensile value, dry”) represent the arithmetic mean of 10 measurements in each case.

(29) The tensile values of the resultant nonwoven web were also measured in the wet state. For this purpose, samples of the respectively resultant nonwoven webs measuring 10×10 cm were cut out, after drying and removal of the binder by condensation, the dry weight of the sample was determined and 11 ml of various lotions 9 to 30 were added per sample. The composition of lotions 9 to 30 used is shown in Table 5. The stated % by weight are based in each case on the total weight of the lotion.

(30) TABLE-US-00006 TABLE 5 Composition of lotions 9 to 30 Lotion composition [% by weight] Lotion No. Amphoteric amine used Amine CaCl.sub.2 × 2H.sub.2O 1,2-Propanediol Ethanol Water 9 Ca-L-Lysine 4.9  0.25 45 8.6 41.25 10 L-Proline 5.3 — 45 8.5 41.2 11 Ca-L-Proline 5.1 1.8 34.3 5.1 53.7 12 Ca-L-Ornithine 5.0 1.8 34.4 5.1 53.7 13 Ca-L-Arginine 5.2 1.8 34.2 5.1 53.7 14 Ca-L-Glycine 5.1 1.8 31.9 7.5 53.7 15 Ca-L-Alanine 6.4 1.7 17.0 21.2 53.7 16 Ca-L-Leucine 7.5 2.0 21.7 15.1 53.7 17 Ca-L-Histidine 5.2 1.8 30.8 8.5 53.7 18 Ca-L-Asparagine × H2O 5.1 1.6 25.4 14.2 53.7 19 Ca-L-Glutamine 5.4 2.2 24.5 14.2 53.7 20 Ca-L-Phenylalanine 6.4 1.7 26.2 12.0 53.7 21 Ca-L-Threonine, tech. 5.0 1.9 29.4 10.0 53.7 22 Ca-L-Methionine, tech. 5.1 1.7 29.3 10.2 53.7 23 Ca-L-Tryptophan, tech. 5.4 1.8 29.6 9.5 53.7 24 Ca-L-Valine 6.4 1.8 25.1 13.0 53.7 25 Ca-L-Aspartic acid 7.5 2.5 27.3 9.0 53.7 26 Ca-L-Glutamic acid 6.4 2.5 27.9 9.5 53.7 27 Ca-L-Cysteine 5.0 1.9 28.4 11.0 53.7 28 Ca-L-Dihydroxyphenylalanine 5.4 1.9 26.0 13.0 53.7 29 Ca-L-Isoleucine 5.2 1.7 27.4 12.0 53.7 30 Ca-L-Serine 5.1 1.8 31.9 7.5 53.7

(31) The amphoteric amines labelled with “Ca-” in Table 5 were used in the form of the calcium salt of the corresponding L-amino acid. Prior to use in the corresponding lotion, the amount of the amphoteric amine reported in Table 5 was first dissolved in distilled water together with the amount of CaCl.sub.2×2×H.sub.2O reported in Table 5, and this solution was added to the corresponding lotion.

(32) The tensile values of the nonwoven webs produced, in the dry state and after wetting with lotions 9 to 30, are summarized in Table 6.

(33) Additionally, a determination was made of the disintegration time in water in analogy to the EDANA Test FG502 (“Slosh Box Disintegration Test”) (EDANA=European Disposables and Nonwovens Association) at 20° C. on 10 samples in each case.

(34) For this purpose, the wetted samples were each placed in a test vessel containing 2 l of mains water (temperature: 20° C., total hardness: 13.5° dH [German hardness], conductivity at 20° C.: 412 μS/cm, pH: 7.5) and incubated without stirring. The disintegration time was determined by visual inspection. The disintegration times reported in Table 6 represent the arithmetic mean from 10 measurements in each case.

(35) Following their disintegration, the samples were incubated in the test vessel at 20° C. without stirring for a total of 3 hours in each case, after which they were passed through a perforated sieve (mesh size: 12.5 mm). The material remaining on the sieve was collected, dried and weighed.

(36) Since less than 10% by weight, based on the dry weight of the sample as determined beforehand in each case, remained on the sieve for each of the samples tested, the EDANA test was rated as a pass for each of the solutions investigated.

(37) The results of the disintegration test in water are likewise summarized in Table 6.

(38) TABLE-US-00007 TABLE 6 Dry strength values and wet strength values of nonwoven webs impregnated with lotions 9 to 30 Lotion Tensile value, dry Tensile value, wet Disintegration in water No. [N] [N] [s] 9 48 8.6 20 10 50 8.5 <10 11 54 14.6 35 12 54 12 25 13 54 12 25 14 54 8.5 <10 15 54 13.2 25 16 48 11 35 17 51 9 40 18 54 12 20 19 55 12 20 20 48 13 40 21 48 8 30 22 55 9.5 35 23 49 9 25 24 54 11 30 25 49 8.5 15 26 47 8.1 <10 27 54 10.5 25 28 52 11 40 29 55 11.5 35 30 48 9.6 30

(39) The wet strengths achieved for the samples impregnated with lotions 10 to 30 are analogous, with fluctuations, to those of lysine (Lotion 9).

COMPARATIVE EXAMPLE 5

(40) In analogy to the cleaning sheet described in EP 0 372 388 A2, the nonwoven webs 1a and 1e produced in examples 1 were treated with lotions containing no amphoteric amine. For this purpose, samples of the respective nonwoven webs measuring 10×10 cm were cut out, after drying and removal of the binder by condensation, and 11 ml of different lotions 31 and 32 were added per sample. The composition of the lotions 31 and 32 used is shown in Table 7. The reported % by weight are based in each case on the total weight of the lotion.

(41) After incubation at room temperature for 60 minutes, the tensile values of the wetted samples were measured at room temperature in a tensile test in analogy to DIN 54540-8 by pulling in machine direction. The tensile values reported below (“Tensile value, wet”) represent the arithmetic mean from 10 measurements in each case.

(42) TABLE-US-00008 TABLE 7 Wet strength values when using lotions 31 and 32 Binders Finnfix 700 Rheolon 30 Applied amount [g/m.sup.2] 1.29 1.75 Lotion Composition [% by weight] Tensile value, wet No. Amphoteric amine CaCl.sub.2 × 2 H.sub.2O 1,2-Propanediol Ethanol Water [N] 31 — 2.2 — 22.8 75.0 5.2 6.3 32 — 2.2 — 10.0 87.8 3.7 0.8

(43) The wet strengths achieved without use of an amphoteric amine, such as of an L-amino acid, for example, were significantly lower.

INVENTIVE EXAMPLE 6 AND COMPARATIVE EXAMPLE 7

(44) To test the storage stability of the wetted samples in the presence and absence, respectively, of an amphoteric amine, the nonwoven webs 1a and 1e produced in examples 1 were treated with different lotions and then stored in the corresponding lotion for 30 days before the wet strength was measured.

(45) For this purpose, samples of the respective non woven webs measuring 10×10 cm were cut out, after drying and removal of the binder by condensation, and 11 ml of the corresponding lotions 31 and 32 from comparative example 5 and also lotions 6, 7 and 8 from inventive example 3 were added per sample. The composition of the lotions used is shown in Table 8. The reported % by weight are based in each case on the total weight of the lotion.

(46) After incubation at room temperature for 60 minutes, the tensile values of the wetted samples were measured at room temperature (“after 60 min”) in a tensile test in analogy to DIN 54540-8 by pulling in the machine direction. Further samples were stored in the corresponding lotion for 30 days in closed vessels at room temperature (25° C.), before the tensile values of the wetted samples were measured at room temperature (“after 30 days”) in a tensile test in analogy to DIN 54540-8 by pulling in machine direction. The tensile values reported below (“Tensile value, wet”) represent the arithmetic mean from 10 measurements in each case.

(47) TABLE-US-00009 TABLE 8 Comparison of the wet strengths after 30-day storage at room temperature Binder Finnfix 700 Rheolon 30 Finnfix 700 Rheolon 30 Applied amount [g/m.sup.2] 1.29 1.75 1.29 1.75 Lotion after 60 min after 30 days Composition [% by weight] Tensile value, wet Tensile value, wet No. Lysine CaCl.sub.2 × 2 H.sub.2O 1,2-Propanediol Ethanol Water [N] [N] 31 — 2.2 — 22.8 75.0 5.2 6.3 1.5 1.1 32 — 2.2 — 10.7 87.8 3.7 0.8 <1 <1 6 10.0 — 34.0 13.0 43.0 9.1 8.2 9.0 8.8 7 9.4 3.8 42.2 4.7 39.9 17.3 15.0 18 16.2 8 6.5 5.2 39.0 4.3 45.0 19.6 19.0 19.5 19.2

(48) The stability of the wet strength under the respective storage conditions was achieved only by lotions containing the amphoteric amine.

(49) The systems without amphoteric amine, amino acid for example, were unsuitable for producing marketable products in this regard. Storage for just 30 days in each of the lotions 31 and 32 used resulted in a significant reduction in the wet strength, which made further use as moist toilet paper, for example, impossible.

(50) In contrast to this, when using one of the lotions 6 to 8, no significant reduction in the wet strength after 30 days was found. As a result, when wet wipes are stored in the corresponding lotion, in a bulk pack, for example, by the end user for at least 30 days, there is no substantial decrease in the mechanical robustness of a wet wipe or moist toilet paper when used by the end user.