ACID-RESISTANT AND ALKALI-RESISTANT COMPOSITION

Abstract

The present invention relates to an acid-resistant and alkali-resistant composition, a preparation process thereof and use thereof in producing an article, and an article comprising a substrate coated or impregnated with the same and the preparation method and use of the article. The composition contains: at least one aqueous polyurethane dispersion having a carboxyl group; at least one crosslinking agent having an isocyanate reactive group; at least one crosslinking agent having a carboxyl reactive group; and optionally an additive; wherein, the amount of the carboxyl groups in said aqueous polyurethane dispersion is more than 0.05 wt %, based on the amount of said aqueous polyurethane dispersion being 100 wt %; the amount of said crosslinking agent having an isocyanate reactive group is 0.2 wt %-10 wt %, based on the amount of said composition being 100 wt %; the molar ratio of the carboxyl reactive groups to the carboxyl groups of said composition is more than 0.5. The film formed with the composition of the present invention has good acid-resistance and alkali-resistance. The product obtained by treating with the composition of the present invention has flat appearance and good handfed.

Claims

1. A composition, comprising: at least one aqueous polyurethane dispersion having a carboxyl group; at least one crosslinking agent having an isocyanate reactive group; at least one crosslinking agent having a carboxyl reactive group; and optionally an additive; wherein, an amount of the carboxyl groups in said aqueous polyurethane dispersion is more than 0.05 wt %, based on a total amount of said aqueous polyurethane dispersion; an amount of said crosslinking agent having an isocyanate reactive group is 0.2 wt %-10 wt %, based on a total amount of said composition; a molar ratio of the carboxyl reactive groups to the carboxyl groups of said composition is more than 0.5.

2. The composition according to claim 1, wherein said aqueous polyurethane dispersion comprises a polyurethane obtained by the reaction of a system comprising an isocyanate and a polymer polyol, said polymer polyol comprising a polyether polyol a polycarbonate polyol, or a combination thereof.

3. The composition according to claim 1, wherein said aqueous polyurethane dispersion comprises a polyurethane obtained by the reaction of a system comprising the following components: A1) at least one polyisocyanate having an isocyanate functionality of not less than 2; A2) at least two different polytetramethylene ether glycols A2a) and A2b), said A2a) having a number average molecular weight of not more than 1500 g/mol, said A2b) having a number average molecular weight of more than 1500 g/mol; and A3) at least one anionic or potentially anionic hydrophilic agent having a number average molecular weight of 32 g/mol-400 g/mol and having hydroxyl and carboxyl groups; B) at least one anionic or potentially anionic hydrophilic agent having an amino functionality; C) at least one amino functional compound having no hydrophilic group and having a number-average molecular weight of 32 g/mol-400 g/mol; and D) optionally a neutralizer; wherein a ratio of the number average molecular weight of said A2a) to the number average molecular weight of said A2b) is 1:9-4:1, and wherein a weight of said A3) is 20%-70% of a total weight of hydrophilic agent of said system.

4. The composition according to claim 3, wherein said A1) polyisocyanate comprises an aliphatic polyisocyanate, a cycloaliphatic polyisocyanate, or a combination thereof, optionally wherein said A1) polyisocyanate comprises hexamethylene diisocyanate, isophorone diisocyanate, or a combination thereof.

5. (canceled)

6. The composition according to claim 3, wherein said A2a) has a number average molecular weight of 400 g/mol-1500 g/mol, said A2b) has a number average molecular weight of more than 1500 g/mol and less than equal to 8000 g/mol, or both.

7. (canceled)

8. The composition according to claim 3, wherein said A3) anionic or potentially anionic hydrophilic agent having a number average molecular weight of 32 g/mol-400 g/mol and having hydroxyl and carboxyl groups is dimethylolpropionic acid.

9. The composition according to claim 3, wherein the ratio of the number average molecular weight of said A2a) to the number average molecular weight of said A2b) is 1:4-7:3.

10. The composition according to claim 3, wherein the weight of said A3) is 20%-60%, based on the total weight of hydrophilic agent of said system.

11. The composition according to claim 3, wherein said B) anionic or potentially anionic hydrophilic agent having an amino functionality is sodium 2-[(2-aminoethyl)amino]ethanesulfonate.

12. The composition according to claim 3, wherein a molar amount of said D) neutralizer is less than equal to 50 mol %, based on a molar amount of said A3).

13. The composition according to claim 1, wherein said crosslinking agent having an isocyanate reactive group is a hydrophilically modified aliphatic isocyanate crosslinking agent.

14. The composition according to claim 1, wherein said crosslinking agent having a carboxyl reactive group is a hydrophilically modified carbodiimide.

15. A process for preparing the composition according to claim 1, comprising: mixing said aqueous polyurethane dispersion having a carboxyl group, said crosslinking agent having an isocyanate reactive group, said crosslinking agent having a carboxyl reactive group and optionally said additive in any manner.

16. The process according to claim 15, wherein the process for preparing said aqueous polyurethane dispersion further comprises the following steps: I) mixing and reacting A1) at least one polyisocyanate having an isocyanate functionality of not less than 2; A2) at least two different polytetramethylene ether glycols A2a) and A2b), said A2a) having a number average molecular weight of not more than 1500 g/mol, said A2b) as having a number average molecular weight of more than 1500 g/mol; and A3) at least one anionic or potentially anionic hydrophilic agent having a number average molecular weight of 32 g/mol-400 g/mol and having hydroxyl and carboxyl groups to obtain an isocyanate functional pre-polymer; II) reacting said isocyanate functional pre-polymer, B) at least one anionic or potentially anionic hydrophilic agent having an amino functionality, C) at least one amino functional compound having no hydrophilic group and having a number-average molecular weight of 32 g/mol-400 g/mol, and optionally D) a neutralizer to obtain a polyurethane; and III) introducing water before, during or after step II) to obtain said aqueous polyurethane dispersion; wherein a ratio of the number average molecular weight of said A2a) to the number average molecular weight of said A2b) is 1:9-4:1, and wherein a weight of said A3) is 20%-70% of a total weight of hydrophilic agent of said system.

17. A method of producing an article, comprising utilizing the composition according to claim 1 to produce the article.

18. An article comprising a substrate coated or impregnated with the composition according to claim 1, optionally wherein the substrate is a superfine fiber.

19. (canceled)

20. (canceled)

21. A process for producing an article, comprising the following steps: i) impregnating sea-island type bicomponent superfine fibers into the composition according to claim 1; ii) taking out and drying sea-island type bicomponent superfine fibers treated in step i), and then impregnating the sea-island type bicomponent superfine fibers into hot alkali or hot water to remove the sea component in the fibers to obtain superfine fibers; and iii) taking out and drying the superfine fibers to obtain said article.

22. The process according to claim 21, further comprising a step iv) between said step ii) and said step iii) of taking out and drying the superfine fiber treated in the step ii), and then impregnating the superfine fiber in a dye.

23. A process for producing an article, comprising the following steps: a) impregnating sea-island type bicomponent superfine fibers into hot alkali or hot water to remove the sea component in the fibers to obtain superfine fibers; b) taking out and drying the superfine fibers treated in step a), and then impregnating the superfine fibers into the composition according to claim 1; and c) taking out and drying the superfine fibers to obtain said article.

24. The process according to claim 23, further comprising a step d) between said step b) and said step c) of taking out and drying the superfine fiber treated in the step b), and then impregnating the superfine fiber in a dye.

Description

DESCRIPTION OF THE DRAWINGS

[0141] The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0142] FIG. 1 is an external view of a superfine fiber nonwoven fabric sample obtained by the impregnation with the composition of Example 6, wherein the superfine fiber nonwoven fabric sample has a flat appearance and few wrinkles.

[0143] FIG. 2 is an external view of a superfine fiber nonwoven fabric sample obtained by the impregnation with the comparative composition of Comparative Example 12, wherein the superfine fiber nonwoven fabric sample has an uneven appearance and many wrinkles.

EXAMPLES

[0144] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. When a definition of a term in the specification contradicts a meaning commonly understood by a person skilled in the art to which the present invention belongs, the definition described herein dominates.

[0145] Unless otherwise indicated, all numbers expressing the ingredient amount, the reaction condition and the like used in the specification and claims are to be understood as being modified with the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth herein are approximations that may vary depending upon the desired properties that need to be obtained.

[0146] The expression “and/or” as used herein refers to one or all of the mentioned elements.

[0147] As used herein, the expressions “ . . . or more” and “ . . . or less” include the recited values themselves, unless otherwise indicated.

[0148] As used herein, the terms “comprising” and “containing” encompass the situation where only the mentioned element is present as well as the situation where there are other unrecited elements in addition to the mentioned element.

[0149] The analytical measurement in the present invention is carried out at 23° C., unless otherwise stated.

[0150] The percentage used in the present invention is by weight, unless otherwise indicated.

[0151] The solid content of the aqueous polyurethane dispersion is determined using a HS153 moisture meter from the Mettler Toledo company in accordance with DIN-EN ISO 3251.

[0152] The number average molecular weight is determined with the gel permeation chromatography in tetrahydrofuran at 23° C. against the polystyrene standard.

[0153] The hydroxyl number is determined in accordance with ASTM D4274.

[0154] The isocyanate group (NCO) content is determined by volume in accordance with DIN-EN ISO 11909, and the determined data include the free and potentially free NCO contents.

[0155] The functionality of the isocyanate group is determined in accordance with GPC.

[0156] The particle size of the aqueous polyurethane dispersion is determined after dilution with deionized water using the laser spectroscopy (measured with the Zatasizer Nano ZS 3600 laser particle sizer from the Malvern instrument company).

[0157] The viscosity is measured at 23° C. in accordance with DIN 53019 using the DV-II+Pro. rotational viscometer from the Brookfield company.

[0158] The pH value of the aqueous polyurethane dispersion is measured at 23° C. using a PB-10 pH meter from the Sartorius company (Germany).

Raw Materials and Reagents

[0159] Impranil® 1701: an aqueous anionic aliphatic polycarbonate polyurethane dispersion, having a solid content of 40 wt %, and based on a polycarbonate polyol, a carboxylic acid group of 0.3 wt %, commercially available from Covestro Co., Ltd.

[0160] Impranil® DLU: an aqueous anionic/nonionic aliphatic polycarbonate-polyether polyurethane dispersion, having a solid content of 60 wt %, free of carboxyl group, based on the combined polyol of polyether polyol and polycarbonate polyol, commercially available from Covestro Co., Ltd.

[0161] Imprafix® 2794: a hydrophilically modified blocked aliphatic isocyanate crosslinking agent, having a solid content of 38 wt %, an isocyanate group (NCO) content of 12.7 wt % (based on the solid content), and a viscosity of <1500 mPa.Math.s, commercially available from Covestro Co., Ltd.

[0162] Imprafix® 3025: a hydrophilically modified unblocked aliphatic isocyanate crosslinking agent, having a solid content of 100 wt %, an isocyanate group content of 16.2 wt %, and a viscosity of 6500±1500 mPa.Math.s, commercially available from Covestro Co., Ltd.

[0163] Desmodur® 2802: a hydrophilically modified carbodiimide crosslinking agent, having a solid content of 40 wt %, and an NCN group content of 4.2 wt %, commercially available from Covestro Co., Ltd.

[0164] Desmodur®H: 1,6-hexamethylene diisocyanate, commercially available from Covestro Co., Ltd. (Germany).

[0165] Desmodur®I: isophorone diisocyanate, commercially available from Covestro Co., Ltd. (Germany).

[0166] polytetramethylene ether glycol 1000: having a hydroxyl number of 112 mg KOH/g, a hydroxyl functionality of 2, and a number-average molecular weight of 1000 g/mol, commercially available from BASF Corp. (Germany).

[0167] Polytetramethylene ether glycol 2000: having a hydroxyl number of 56 mg KOH/g, a hydroxyl functionality of 2, and a number-average molecular weight of 2000 g/mol, commercially available from BASF Corp. (Germany).

[0168] Dimethylolpropionic acid, commercially available from Aldrich Chemical Co. Inc. (Germany).

[0169] Sodium 2-[(2-aminoethyl)amino]ethanesulfonate solution: NH.sub.2—CH.sub.2CH.sub.2—NH—CH.sub.2CH.sub.2—SO.sub.3Na, having a concentration of 45% in water, commercially available from Covestro Co., Ltd. (Germany).

[0170] Ethylene diamine, commercially available from Jiaxing Jinyan chemical Co., Ltd., China.

[0171] Sodium hydroxide: analytically pure, commercially available from Sinopharm Chemical Reagent Co. Ltd.

[0172] Acetic acid: analytically pure, commercially available from Kelin Reagent Co. Ltd.

[0173] Borchi Gel®ALA: a polyacrylic acid-type thickener, having a non-volatile component's content of 9 wt %-11 wt %, commercially available from Borchers GmbH.

[0174] LYOPRINT®PTF: a polyacrylic acid-type thickener, having an active ingredient content of <60 wt %, commercially available from Xianhua (Shanghai) Bio Chemical Co., Ltd.

[0175] BYK® 333: polyether modified silicone, available from BYK Additives & Instruments.

[0176] Superfine fiber nonwoven fabric, commercially available.

Preparation of the Aqueous Polyurethane Dispersion A

[0177] 1015 g of polytetramethylene ether glycol 2000, 217.5 g of polytetramethylene ether glycol 1000, 15.6 g of dimethylolpropionic acid, 144.4 g of Desmodur®I and 109.3 g of Desmodur®H were mixed at 70° C., heated to 110° C. and stirred at this temperature until the actual value of the isocyanate groups (NCO) of the pre-polymer was the theoretical value of NCO or less. The pre-polymer was dissolved in 2669.7 g of acetone at 90° C., stirred for 20 minutes and then cooled to 40° C. Then, 12.4 g of ethylene diamine, 50.2 g of a sodium 2-[(2-aminoethyl)amino] ethanesulfonate solution and 310.1 g of water were metered in, and stirred for 20 minutes. Then 1967.3 g of water was added for dispersion, and the solvent was removed by the distillation in vaccum to obtain an aqueous polyurethane aqueous dispersion A, having a solid content of 41.8 wt %, a viscosity of 159 mPa.Math.s (23° C.), a pH of 6.7, a carboxyl group content of 0.13 wt % and a particle size of 163.5 nm.

The Compositions of Examples 1-5 and Comparative Examples 1-11

[0178] Table 1 lists the components of the compositions of Examples 1-5 and Comparative Examples 1-11.

TABLE-US-00001 TABLE 1 Components of the compositions of Examples and Comparative Examples Molar ratio of carboxyl Components of the composition reactive group Crosslinking Crosslinking Example/ to carboxyl Aqueous agent having an agent having a Comparative group of the polyurethane isocyanate carboxyl reactive Example composition dispersion reactive group group Example 1 1 100 parts of 5 parts of 3 parts of aqueous Imprafix ®2794 Desmodur ®2802 polyurethane dispersion A Example 2 1 100 parts of 3 parts of 3 parts of aqueous Imprafix ®2794 Desmodur ®2802 polyurethane dispersion A Example 3 2 100 parts of 5 parts of 6 parts of aqueous Imprafix ®2794 Desmodur ®2802 polyurethane dispersion A Comparative 0.5 100 parts of 5 parts of 1.5 parts of Example 1 aqueous Imprafix ®2794 Desmodur ®2802 polyurethane dispersion A Comparative 0 100 parts of 3 parts of Example 2 aqueous Imprafix ®3025 polyurethane dispersion A Comparative 1 100 parts of 3 parts of Example 3 aqueous Desmodur ®2802 polyurethane dispersion A Comparative 0 100 parts of Example 4 aqueous polyurethane dispersion A Example 4 0.85 100 parts of 5 parts of 6 parts of Impranil ®1701 Imprafix ®2794 Desmodur ®2802 Comparative 0.14 100 parts of 5 parts of 1 part of Example 5 Impranil ®1701 Imprafix ®2794 Desmodur ®2802 Comparative 0 100 parts of 5 parts of Example 6 Impranil ®1701 Imprafix ®2794 Comparative 0 100 parts of Example 7 Impranil ®1701 Example 5 1.2 50 parts of 3 parts of 6 parts of aqueous Imprafix ®3025 Desmodur ®2802 polymethane dispersion A, 50 parts of Impranil ®1701 Comparative 0 50 parts of 3 parts of Example 8 aqueous Imprafix ®3025 polymethane dispersion A, 50 parts of Impranil ®1701 Comparative 0.2 50 parts of 3 parts of 1 part of Example 9 aqueous Imprafix ®3025 Desmodur ®2802 polymethane dispersion A, 50 parts of Impranil ®1701 Comparative 0 50 parts of Example 10 aqueous polymethane dispersion A, 50 parts of Impranil ®1701 Comparative / 100 parts of 5 parts of 3 parts of Example 11 Impranil ®DLU Imprafix ®2794 Desmodur ®2802 Note: parts in Table 1 are parts by weight

[0179] In the present invention, the composition is used to prepare a film, and the weight/volume ratio of the film is tested to characterize the acid-resistance and the alkali-resistance, particularly the hot acid-resistance and the hot alkali-resistance of the film formed with the composition. An article is prepared by using a superfine fiber non-woven fabric impregnation process, and the appearance of the article is observed.

The Process for Preparing the Films with Compositions of Examples 1-5 and Comparative Examples 1-11 and the Test Method for the Weight/Volume Ratio of the Films [0180] 1. The compositions of Examples and Comparative examples were obtained by mixing the components of the compositions according to Table 1 uniformly, and the viscosity of the compositions was adjusted to about 5000 mPa.Math.s by using Borchi Gel®ALA.

[0181] The composition was scraped on a flat and smooth surface with a film scraper to prepare a wet film with the thickness of 500 μm, and a dry film sample was obtained by drying the wet film at 50° C. for 30 minutes and at 150° C. for 3 minutes in sequence; [0182] 2. A half of the dry film was taken and a piece of 5 cm*2 cm was cut therefrom. The thickness and the weight of said piece of the dry film were measured, wherein the thickness of the film sample was recorded as T.sub.0, and the weight of the film sample was recorded as S.sub.0; [0183] 3. After the weight of the dry film was measured, the dry film was put into a test dyeing cup. A NaOH solution with the concentration of 1.5% was added in an amount 15 times as large as the weight of the dry film. The test dyeing cup was put into a laboratory sample dyeing machine, and a high-temperature alkali treatment was carried out according to the following process conditions:

[0184] Heating from room temperature to 90° C. at a heating speed of 4° C./min, keeping at 90° C. for 15 minutes, and cooling from 90° C. to 50° C. at a cooling speed of 3° C./min. The laboratory sample dyeing machine was Model DYE-24 commercially available from Shanghai Qianli automation equipment Co., Ltd.; [0185] 4. After the treatment in the high-temperature alkali condition was completed, the film was taken out and cleaned (if the film was damaged, the subsequent steps were not needed). The film was dried by absorbing water with paper. The film was put into the test dyeing cup again, and an acetic acid solution with a pH of 4 was added in an amount 15 times as large as the weight of the film. The test dyeing cup was put into the laboratory sample dyeing machine, and a high-temperature acid treatment was carried out according to the following process conditions:

[0186] Heating from room temperature to 80° C. at a heating speed of 3° C./min, heating from 80° C. to 130° C. at a heating speed of 1° C./min, keeping at 130° C. for 40 minutes, then cooling from 130° C. to 80° C. at a cooling speed of 1° C./min, and cooling from 80° C. to 50° C. at a cooling speed of 3° C./min; [0187] 5. After the treatment in the high-temperature acid condition was completed, the film was taken out and cleaned, and the length, width and thickness of the film was measured, wherein the length of the treated film sample was recorded as L.sub.1, the width of the treated film sample was recorded as W.sub.1, the thickness of the treated film sample was recorded as T.sub.1, and the swelling ratio R was calculated according to the following calculation formula:

R=(L.sub.1*W.sub.1*T.sub.1/(5*2*T.sub.0))*100%−1 [0188] 6. The film obtained after the treatment through the above steps was dried by absorbing water with paper, and then dried for 10 minutes in a drying oven at 90° C. The dried film was placed in a constant temperature and humidity room for adjustment for 24 hours, and then the weight of the treated film sample was measured and recorded as S.sub.1. The weight loss rate Z of the sample was calculated according to the following calculation formula:

Z=((S.sub.0−S.sub.1)/S.sub.0)*100% [0189] 7. The weight/volume ratio of the film sample obtained after the treatment through the above steps was calculated according to the following calculation:

weight/volume ratio=((1−Z)/(1+R))*100

[0190] The greater the weight/volume ratio was, the better the acid and alkali resistances of the film formed with the composition under the above-described treatment conditions were. When the weight/volume ratio of the film formed with the composition was greater than 80, the acid and alkali resistances of the film were excellent, and the composition was particularly suitable for fiber impregnation applications.

Film Test Results

[0191] Table 2 lists the test results for the weight/volume ratios of the films formed with the compositions of Examples 1-5 and Comparative examples 1-11.

TABLE-US-00002 TABLE 2 Weight/volume ratio test result Example and Swelling Weight loss Weight/volume Comparative Example ratio R (%) rate Z (%) ratio Example 1 19 4.7 80.1 Example 2 19.9 3 80.9 Example 3 12.9 2.2 86.6 Comparative 22.2 5.0 77.8 Example 1 Comparative 30.8 4.6 72.9 Example 2 Comparative 30.9 3.33 73.9 Example 3 Comparative 80.5 film was / Example 4 damaged Example 4 4.2 1.4 94.6 Comparative 76.5 5.7 53.4 Example 5 Comparative 104.6 5 46.5 Example 6 Comparative film was film was / Example 7 damaged damaged Example 5 17.7 2.1 83.2 Comparative 25.7 3.1 77.1 Example 8 Comparative 41.6 2.82 68.6 Example 9 Comparative film was film was / Example 10 damaged damaged Comparative film was film was / Example 11 damaged damaged

[0192] It could be seen from the results of Examples 1-5 that the weight/volume ratios of the films formed with the compositions of the present invention comprising the aqueous polyurethane dispersion having a carboxyl group, the crosslinking agent having a blocked or unblocked isocyanate reactive group and the crosslinking agent having a carboxyl reactive group were more than 80, which indicated that the films formed with the compositions of the present invention had good acid and alkali resistances.

[0193] Although the comparative compositions of Comparative Examples 1, 5 and 9 contained the aqueous polyurethane dispersion having a carboxyl group, the crosslinking agent having a blocked or unblocked isocyanate reactive group and the crosslinking agent having a carboxyl reactive group, the molar ratios of the carboxyl reactive group to the carboxyl group of the comparative compositions were less than equal to 0.5, and the weight/volume ratios of the films formed with the comparative compositions were less than 80, indicating that the films formed with the comparative compositions had poor acid and alkali resistances.

[0194] The comparative compositions of Comparative Examples 2, 6 and 8 did not contain the crosslinking agent having a carboxyl reactive group, the comparative composition of Comparative Example 3 did not contain the crosslinking agent having an isocyanate reactive group, the comparative compositions of Comparative Examples 4, 7 and 10 neither contained the crosslinking agent having a carboxyl reactive group nor the crosslinking agent having an isocyanate reactive group, the weight/volume ratios of the films formed with the above comparative compositions were less than 80, or the films formed with the above compositions were damaged, that was to say, the films formed with the above comparative compositions had poor acid and alkali resistances.

[0195] The aqueous polyurethane dispersion in the comparative composition of Comparative Example 11 had no carboxyl group, and the film formed with the comparative composition was damaged, i.e., the film formed with the comparative composition had poor acid and alkali resistances.

Impregnation Treatment of Superfine Fiber Nonwoven Fabric

[0196] 1. The components of the compositions were uniformly mixed according to the compositions of Example 6 and Comparative Example 12, respectively. The viscosity of the compositions was adjusted with the LYOPRINT® PTF thickener to about 50 mPa.Math.s (viscosity measurement condition: Brookfield viscometer, 63# rotor, 100 rpm). The superfine fiber nonwoven fabric was completely immersed in the composition. The superfine fiber nonwoven fabric was taken out and the excess slurry was removed by rolling with a laboratory rolling mill. Then superfine fiber nonwoven fabric was dried in an oven at 70° C., and finally cured in an oven at 150° C. for 3 minutes to obtain a superfine fiber nonwoven fabric sample; [0197] 2. After the weight of the superfine fiber non-woven fabric sample obtained from the treatment in the previous step 1 was measured, the fabric sample was put into a test dyeing cup. A NaOH solution with the concentration of 1.5% was added in an amount 15 times as large as the weight of the fabric sample. The test dyeing cup was put into a laboratory sample dyeing machine, and a high-temperature alkali treatment was carried out according to the following process conditions:

[0198] Heating from room temperature to 90° C. at a heating speed of 4° C./min, keeping at 90° C. for 30 minutes, and cooling from 90° C. to 50° C. at a cooling speed of 3° C./min. The laboratory sample dyeing machine was Model DYE-24 commercially available from Shanghai Qianli automation equipment Co., Ltd.; [0199] 3. After the treatment in the high-temperature alkali condition was completed, the fabric sample was taken out and cleaned (if the film was damaged, the subsequent steps were not needed). The film was dried by absorbing water with paper. The film was put into the test dyeing cup again, and an acetic acid solution with a pH of 4 was added in an amount 15 times as large as the weight of the film. The test dyeing cup was put into the laboratory sample dyeing machine, and a high-temperature acid treatment was carried out according to the following process conditions:

[0200] Heating from room temperature to 80° C. at a heating speed of 3° C./min, heating from 80° C. to 130° C. at a heating speed of 1° C./min, keeping at 130° C. for 40 minutes, cooling from 130° C. to 80° C. at a cooling speed of 1° C./min, and cooling from 80° C. to 50° C. at a cooling speed of 3° C./min; [0201] 4. After the high-temperature acid treatment, the superfine fiber nonwoven fabric sample was taken out and cleaned, and then dried in a drying oven at 90° C. The superfine fiber nonwoven fabric sample was taken out from the drying oven, and its appearance was observed.

Example 6

[0202] The components of the composition was as follows: 100 parts by weight of aqueous polyurethane dispersion A, 5 parts by weight of Desmodur® 2802, 5 parts by weight of Imprafix® 2794, 205 parts by weight of deionized water and 0.7 part by weight of BYK®333. The solid content of the composition was about 13 wt %. The appearance of the superfine fiber nonwoven fabric sample obtained from the above superfine fiber nonwoven fabric impregnation treatment was shown in FIG. 1.

Comparative Example 12

[0203] The components of the comparative composition was as follows: 100 parts by weight of Impranil® DLU, 2 parts by weight of Desmodur® 2802, 5 parts by weight of Imprafix® 2794, about 345 parts by weight of deionized water and 0.7 part by weight of BYK 333. The solid content of the composition was about 13 wt %. The appearance of the superfine fiber nonwoven fabric sample obtained from the above superfine fiber nonwoven fabric impregnation treatment was shown in FIG. 2.

[0204] As can be seen from FIGS. 1 and 2, compared with Comparative Example 12, the superfine fiber nonwoven fabric sample prepared from the composition of Example 6 was smoother and crease-free, indicating that the composition of Example 6 was more suitable for the superfine fiber impregnation process than the comparative composition of Comparative example 12.

[0205] It will be apparent to those skilled in the art that the present invention is not limited to the specific details described above, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are therefore to be considered in all respects as illustrative and not restrictive. The scope of the invention is thus indicated by the appended claims rather than by the foregoing description. Therefore, any modification, as long as it falls within the meaning and scope of the claims equivalent, should be considered as belonging to the present invention.