A bio-based fluorine-free water repellent for synthetic leather and preparation method thereof

Abstract

The present invention provides a method for preparing a bio-based fluorine-free water repellent for synthetic leather, which includes the following steps: 1) reacting a bio-based polyol with a special isocyanate to obtain a multi-functional end-capped intermediate; 2) subjecting the multi-functional end-capped intermediate to an ester exchange to obtain an outwardly extending bio-based long carbon chain end to obtain a bio-based fluorine-free water repellent. The present invention also creatively proposes a bio-based fluorine-free water repellent for synthetic leather, which is prepared by any of the above methods. The present invention selects bio-based raw materials and effectively regulates the functionality in the reaction process in the structure, designs the outwardly extending water-repellent chain segments, and makes the water repellent have good performance. The water repellent prepared by the present invention is fluorine-free and easier to degrade, low-carbon and environmentally friendly, and conforms to the concepts of green chemical industry and renewable.

Description

Technical Field

[0001] The invention belongs to the field of chemical technology, and in particular relates to a bio-based fluorine-free water repellent for synthetic leather and a preparation method thereof. Background Art

[0002] Water repellent can give leather, upper leather and other materials excellent waterproof effect and lasting waterproof, oil-proof and anti-fouling properties. At the same time, the color, feel and air permeability of the substrate itself will not change. Polyurethane resin has good film-forming properties. When coated with polyurethane resin containing water repellent, the surface of synthetic leather can obtain excellent water impact resistance, water penetration resistance, water repellency and hydrostatic pressure resistance. Therefore, water repellent is widely used in the field of synthetic leather.

[0003] Currently, fluorinated water repellents are mostly used in the market. Due to the characteristics of fluorine atoms, fluorinated water repellents have excellent water repellency. The production process of these high-performance fluorinated derivatives inevitably brings about perfluorooctanoic acid (PFOA) or perfluorooctane sulfonic acid (PFOS) residues, which are one of the most difficult to degrade organic pollutants found in the world. They are persistent, bioaccumulative and biotoxic. They are difficult to continue to degrade in the natural environment and pose a great threat to human health and the living environment. In the face of the global trend of banning PFOA, it is particularly urgent to develop their substitutes.

[0004] The Chinese invention patent application with publication number CN112646118A provides a method for preparing a fluorine-free water repellent for polyurethane. By using a polymerized silicone oil polyol with two functional groups as the main material, the technical solution avoids using fluoropolymer as the raw material for the reaction. However, as the main material, the polymerized silicone oil polyol is still not easy to degrade and is prone to produce harmful substances or residues. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a bio-based fluorine-free water repellent for synthetic leather in view of the above problems.

[0006] Another object of the present invention is to provide a bio-based fluorine-free water repellent for synthetic leather in view of the above problems.

[0007] The present invention creatively proposes a method for preparing a bio-based fluorine-free water repellent for synthetic leather, comprising the following steps:

[0008] 1) Reaction of bio-based polyols with special isocyanates to obtain multi-functional capped intermediates;

[0009] 2) The multifunctional capped intermediate is then subjected to ester exchange to obtain a bio-based long carbon chain end extending outward, thereby obtaining a bio-based fluorine-free water repellent.

[0010] In the above-mentioned method for preparing a bio-based fluorine-free water repellent for synthetic leather, the specific method of step 1) includes:

[0011] First, the bio-based polyol is heated to above 100°C for vacuum dehydration, then cooled to 50-60°C and special isocyanate is added. Under the protection of an inert gas atmosphere, an organic bismuth catalyst is added and the temperature is raised to 75-80°C for reaction.

[0012] In the above-mentioned method for preparing a bio-based fluorine-free water-repellent for synthetic leather, the dehydration time is 0.5-1.5 hours, and the reaction time is 2-3 hours.

[0013] In the above-mentioned method for preparing a bio-based fluorine-free water-repellent for synthetic leather, the molar ratio of the bio-based polyol to the special isocyanate is 0.95-1.0:3.05-3.15; and the added amount of the organic bismuth catalyst is 0.05-0.4% of the mass of the bio-based polyol.

[0014] In the above-mentioned method for preparing a bio-based fluorine-free water repellent for synthetic leather, it is characterized in that the bio-based polyol includes at least one of castor oil and hydrogenated castor oil.

[0015] In the above-mentioned method for preparing a bio-based fluorine-free water-repellent for synthetic leather, the special isocyanate includes methyl-(3-isocyanatepropyl)dimethylsilane.

[0016] In the above-mentioned method for preparing a bio-based fluorine-free water repellent for synthetic leather, the specific method of step 2) includes:

[0017] After the reaction in step 1) is completed, the reaction system is cooled to 50-60°C, and then N,N-dimethylformamide, bio-based small molecule alcohol and catalyst are added under the protection of an inert gas atmosphere, and the temperature is raised to 90-100°C for reaction to obtain a bio-based fluorine-free water repellent.

[0018] In the above-mentioned method for preparing a bio-based fluorine-free water repellent for synthetic leather, the reaction time is 4 to 5 hours.

[0019] In the above-mentioned method for preparing a bio-based fluorine-free water repellent for synthetic leather, the molar ratio of the bio-based polyol to the bio-based small molecule alcohol is 0.95~1.0: 3.1~3.2.

[0020] In the above-mentioned method for preparing a bio-based fluorine-free water repellent for synthetic leather, the catalyst includes sodium citrate, and the added amount of the catalyst is 0.1-2% of the mass of N,N-dimethylformamide.

[0021] In the above-mentioned method for preparing a bio-based fluorine-free water repellent for synthetic leather, the bio-based small molecule alcohol includes at least one of lauryl alcohol, palmityl alcohol, and stearyl alcohol.

[0022] In the above-mentioned method for preparing a bio-based fluorine-free water repellent for synthetic leather, the inert gas includes nitrogen or other protective gases.

[0023] The present invention also creatively proposes a bio-based fluorine-free water repellent for synthetic leather, which is prepared by any of the above methods.

[0024] Compared with the prior art, the advantages of the present invention are:

[0025] The present invention selects bio-based raw materials and effectively regulates the functionality in the reaction process in terms of structure, designs an extended water-repellent segment, and makes the water repellent have good performance. The water repellent prepared by the present invention does not contain fluorine and is easier to degrade, is low-carbon and environmentally friendly, and conforms to the concept of green chemical industry and renewable.

[0026] The invention is used for polyurethane resin, especially for polyurethane resin for synthetic leather, without changing the original process flow, and can meet the requirements of waterproof and other properties.

[0027] The present invention uses castor oil and hydrogenated castor oil as raw materials for bio-based polyols. Compared with other bio-based alcohols, castor oil and hydrogenated castor oil have abundant hydroxyl groups, which is conducive to chemical modification. In addition, castor oil and hydrogenated castor oil have good degradability, which further improves the environmental protection performance of the fluorine-free water repellent. DETAILED DESCRIPTION

[0028] Further illustrated by the following specific examples;

[0029] The present invention will be further described below in conjunction with specific examples, and it should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the appended claims of the application.

[0030] Example 1

[0031] (1) 466.5 g of castor oil was heated to 100 ° C and vacuum dehydrated for 1 hour, then cooled to 50-60 ° C and added with 98.4 g of methyl-(3-isocyanatepropyl)dimethylsilane. Under continuous stirring and nitrogen atmosphere protection, 0.4 g of organic bismuth catalyst was added, and the temperature was raised to 75-80 ° C for reaction for 2-3 hours;

[0032] (2) cooling the mixture to 50-60° C., adding 50 g of N,N-dimethylformamide, 290.6 g of lauryl alcohol, and 0.5 g of sodium citrate to the reaction container under continuous stirring and nitrogen atmosphere protection, and heating the mixture to 90-100° C. for reaction for 4-5 hours to obtain the bio-based fluorine-free water repellent.

[0033] Example 2

[0034] (1) 466.5 g of castor oil was heated to 100 ° C and vacuum dehydrated for 1 hour, then cooled to 50-60 ° C and added with 98.4 g of methyl-(3-isocyanatepropyl)dimethylsilane. Under continuous stirring and nitrogen atmosphere protection, 0.4 g of organic bismuth catalyst was added, and the temperature was raised to 75-80 ° C for reaction for 2-3 hours;

[0035] (2) cooling the mixture to 50-60° C., adding 50 g of N,N-dimethylformamide, 378.1 g of palm alcohol, and 0.5 g of sodium citrate to the reaction container under continuous stirring and nitrogen atmosphere protection, and heating the mixture to 90-100° C. for reaction for 4-5 hours to obtain the bio-based fluorine-free water repellent.

[0036] Example 3

[0037] (1) 466.5 g of castor oil was heated to 100 ° C and vacuum dehydrated for 1 hour, then cooled to 50-60 ° C and added with 98.4 g of methyl-(3-isocyanatepropyl)dimethylsilane. Under continuous stirring and nitrogen atmosphere protection, 0.4 g of organic bismuth catalyst was added, and the temperature was raised to 75-80 ° C for reaction for 2-3 hours;

[0038] (2) cooling the mixture to 50-60° C., adding 50 g of N,N-dimethylformamide, 422 g of stearyl alcohol, and 0.5 g of sodium citrate to the reaction container under continuous stirring and nitrogen atmosphere protection, and heating the mixture to 90-100° C. for reaction for 4-5 hours to obtain the bio-based fluorine-free water repellent.

[0039] Application Examples

[0040] The bio-based fluorine-free water repellent prepared in Examples 1 to 3 was added to the polyurethane resin in an amount of 1 wt % of the polyurethane resin. The performance parameters of the obtained polyurethane resin all met the requirements shown in the following table (the test method refers to QB∕T 4197-2011).

[0041] index Specific requirements Elastic modulus The elastic modulus of the polyurethane resin added with the bio-based fluorine-free water repellent obtained by the present invention is reduced by 0-10% compared with the polyurethane resin without the addition. Surface waterproof level Level 4 and above Hydrolysis resistance More than two weeks Solid content 35~40% Viscosity (cps / 25℃) 5000~10000 color Colorless to light yellow

[0042] The results show that the bio-based fluorine-free water-repellent prepared by the method of the present invention has no obvious effect on the process flow, waterproof performance, etc. of the polyurethane resin. Compared with the fluorine-containing water-repellent and the water-repellent using polymerized silicone oil polyol as raw materials, the bio-based fluorine-free water-repellent of the present invention is more environmentally friendly, in line with the concepts of green chemical industry and renewable energy, and actively promotes the sustainable development of synthetic leather processing technology.

[0043] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0044] Although the terms such as bio-based fluorine-free water repellent, bio-based polyol, special isocyanate, bio-based fluorine-free water repellent are frequently used in this article, these terms are used only to more conveniently describe and explain the essence of the present invention, and interpreting them as any additional limitations is contrary to the spirit of the present invention.

Claims

1. A method for preparing a bio-based fluorine-free water repellent for synthetic leather, characterized in that: The following steps are involved: 1) First, the bio-based polyol is heated to above 100° C. for vacuum dehydration, then cooled to 50-60° C., a special isocyanate is added, and under the protection of an inert gas atmosphere, an organic bismuth catalyst is added, and the temperature is raised to 75-80° C. for reaction to obtain a multi-functional capped intermediate, wherein the special isocyanate includes methyl-(3-isocyanatopropyl)dimethylsilane; the molar ratio of the bio-based polyol to the special isocyanate is 0.95-1.0:3.05-3.15; the amount of the organic bismuth catalyst added is 0.05-0.4% of the mass of the bio-based polyol; 2) After the reaction in step 1) is completed, the reaction system is cooled to 50-60° C., and then N,N-dimethylformamide, bio-based small molecule alcohol and a catalyst are added under the protection of an inert gas atmosphere, and the temperature is raised to 90-100° C. for reaction, and the multi-functional end-capped intermediate is subjected to ester exchange with N,N-dimethylformamide, bio-based small molecule alcohol and a catalyst to obtain an outwardly extending bio-based long carbon chain end, thereby obtaining a bio-based fluorine-free water repellent; the molar ratio of the bio-based polyol to the bio-based small molecule alcohol is 0.95-1.0: 3.1-3.2; the catalyst includes sodium citrate, and the amount of the catalyst added is 0.1-2% of the mass of N,N-dimethylformamide.

2. The method for preparing a bio-based fluorine-free water repellent for synthetic leather according to claim 1, characterized in that: The bio-based polyol includes at least one of castor oil and hydrogenated castor oil.

3. The method for preparing a bio-based fluorine-free water repellent for synthetic leather according to claim 1, characterized in that: The bio-based small molecule alcohol includes at least one of lauryl alcohol, palmityl alcohol and stearyl alcohol.