A DOPO finishing liquid and its preparation method and application

Abstract

The present invention relates to a DOPO finishing liquid and a preparation method and application thereof. The DOPO finishing liquid is composed of DOPO, an alcohol solvent and water, wherein the content of DOPO is 0.5-2.5wt%, the volume ratio of the alcohol solvent to water is 1:4-6, and the boiling point of the alcohol solvent is not less than 70°C; the method is as follows: after dissolving DOPO in an alcohol solvent under stirring conditions, water is added thereto to obtain the DOPO finishing liquid; the application is as follows: after adjusting the pH value of the DOPO finishing liquid to 3-5, a polyamide 6 fabric is immersed therein, taken out and baked, and a flame-retardant polyamide 6 fabric is obtained. The DOPO finishing liquid of the present invention has the characteristics of low concentration and high efficiency, and the solvent used is mainly water, which is green and environmentally friendly; the method of the present invention is simple, and the DOPO finishing liquid of the present invention is applied to polyamide 6 fabric, and has good flame retardant effect and anti-melting droplet effect.

Description

Technical Field

[0001] The invention belongs to the technical field of flame retardant finishing and relates to a DOPO finishing liquid and a preparation method and application thereof. Background Art

[0002] DOPO has been proven to be a green and environmentally friendly phosphorus-containing flame retardant. Therefore, DOPO flame retardant has attracted the interest of many researchers. However, DOPO has poor water solubility and cannot be used to prepare flame-retardant textiles through traditional finishing methods. In addition, DOPO has poor thermal stability, with a decomposition temperature of 200°C, while the blending temperature of polyamide 6 is generally around 260°C. DOPO will decompose and lose its activity before reaching the blending temperature. Therefore, DOPO cannot be directly used for blending modification of polyamide 6 fabrics.

[0003] At present, researchers mainly modify DOPO to improve its thermal stability for the preparation of blended modified polyamide textiles.

[0004] Patent CN106675007A proposes a method for preparing durable flame-retardant polyamide 6 fiber. First, a DOPO-based reactive flame retardant is prepared, and then the polyamide 6 fiber is synthesized through a condensation reaction with caprolactam. However, a variety of synergists need to be added during the preparation process, such as methylphenyl aluminum phosphinate, antimony trioxide, magnesium hydroxide, etc., which has a high economic cost and is not suitable for mass production.

[0005] Document 1 (Insitu prepared polyamide 6 / DOPO-derivative nanocomposite formelt-spinning of flame retardant textile filaments [J]. Polymer Degradation and Stability, 2019, 166: 50-59.) and Document 2 (News sustainable flame retardant DOPO-NH-functionalized polyamide 6 and filament yarn [J]. Chemical Engineering Journal, 2021, 426: 130760.) both use the method of co-spinning to add DOPO derivatives into the polyamide 6 substrate, and the prepared polyamide fibers have reached the UL94V-1 level. The introduction of DOPO derivatives effectively inhibits the dripping of molten droplets and reduces the fire hazard, but does not completely inhibit the dripping of molten droplets. In addition, the addition amount of DOPO derivatives is more than 10%, which has an adverse effect on the strength and spinnability of the fiber.

[0006] In addition, the researchers also used other process methods to utilize the flame retardant properties of DOPO to obtain flame retardant materials.

[0007] Reference 3 (Preparation and properties of flexible flame-retardant polyamide wet-coated fabrics [J]. Journal of Textile Research, 2021, 42(11): 110-116.) uses polyamide 6 waste silk, DOPO, MCA, and methanol / calcium chloride system to prepare slurry, and forms a uniform polyamide film on the fabric surface through a wet coating process. However, the flame-retardant fabric prepared by this system is not a polyamide fabric, and two flame retardants are used. When the dosage of DOPO reaches 8.5%, a good flame retardant effect can be achieved, and the limiting oxygen index reaches 26.4%, but it does not meet the requirements of flame-retardant fabrics (LOI>27%).

[0008] Literature 4 (Supercritical fluid flame-retardant processing of polyethylene terephthalate (PET) fiber treated with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO): Changes in physical properties and flame-retardant performance [J]. Journal of CO2 Utilization, 2021, 54: 101761.) proposes to use supercritical dyeing to allow DOPO to enter the interior of PET fiber to prepare flame-retardant and durable PET fiber. When the addition amount reaches 9%, the limiting oxygen index reaches 30.7%, but the supercritical dyeing conditions are harsh and energy-intensive, which is not suitable for industrial production.

[0009] Therefore, it is of great significance to study a DOPO finishing liquid and its preparation method and application in order to solve the problems of complex process and poor flame retardant effect when DOPO is applied to polyamide 6 fabric in the prior art. Summary of the invention

[0010] The purpose of the present invention is to solve the problems existing in the prior art and to provide a DOPO finishing liquid and a preparation method and application thereof.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A DOPO finishing liquid consists of DOPO, alcohol solvent and water, wherein the content of DOPO is 0.5-2.5wt%, the volume ratio of the alcohol solvent to water is 1:4-6, and the boiling point of the alcohol solvent is not less than 70°C.

[0013] In the DOPO finishing liquid of the present invention, DOPO is in a dissolved state, because DOPO can be well dissolved in alcohol solvents, and water can be miscible with alcohol solvents in any proportion, but water is a poor solvent for DOPO, DOPO will precipitate first, and then DOPO will be in a dissolved state because DOPO produces hydration with water in the presence of alcohol;

[0014] The azeotropic point of the DOPO finishing liquid of the present invention is higher than the temperature of polyamide 6 immersion dyeing (approximately 70-90° C.). Since the volume ratio of alcohol solvent to water is 1:4-6 and the boiling point of alcohol solvent is not lower than 70° C., the azeotropic point of the mixed solvent is higher than 86° C., which can meet the immersion temperature requirement of polyamide 6.

[0015] As the preferred technical solution:

[0016] The DOPO finishing liquid as described above has a solvent with an azeotropic point of 86-90°C.

[0017] In the DOPO finishing solution as described above, the alcohol solvent is ethanol or isopropanol.

[0018] The present invention also provides a method for preparing a DOPO finishing liquid as described in any one of the above items, wherein DOPO is dissolved in an alcohol solvent under stirring conditions, and water is added thereto to obtain the DOPO finishing liquid.

[0019] As the preferred technical solution:

[0020] In the method described above, the stirring temperature is 60-80° C., the stirring time is 15-30 min, and the stirring speed is 800-1000 r / min.

[0021] The present invention also provides an application of a DOPO finishing liquid as described in any of the above items, wherein the pH value of the DOPO finishing liquid is adjusted to 3-5 (DOPO is an acid, referring to acid dyes for dyeing polyamide, so the pH value is within this range), polyamide 6 fabric is immersed in it, taken out and baked to obtain flame-retardant polyamide 6 fabric, wherein the immersion temperature is not higher than the azeotropic point of the DOPO finishing liquid.

[0022] As the preferred technical solution:

[0023] For the application as described above, the immersion temperature is 70-90°C, the immersion time is 50-70min, and the immersion bath ratio is 1:30-50.

[0024] For the application described above, the baking temperature is 130-150° C. and the baking time is 30-60 min.

[0025] In the application described above, the LOI of the flame retardant polyamide 6 fabric is above 27.1%, the damaged length does not exceed 14.8 cm, and the number of droplets is 0; after 20 washes, the LOI of the flame retardant polyamide 6 fabric is above 25.8%, the damaged length does not exceed 16.2 cm, and the number of droplets is 0-1.

[0026] Principle of the Invention

[0027] The present invention first dissolves DOPO with a small amount of alcohol, and then quickly adds a large amount of water. At this time, DOPO will precipitate first and then dissolve again. This method meets the relevant dyeing and finishing requirements, and finally obtains a water / organic solvent system of DOPO. The azeotropic point of this system is higher than the temperature of polyamide 6 immersion dyeing, so polyamide 6 fabric can be prepared by immersion method.

[0028] The polyamide 6 fabric is placed in the prepared flame retardant solution and dyed by imitating acid dyes. The pH value of the flame retardant solution is adjusted to 3-5. The immersion temperature is 70-90°C and the immersion time is 50-70 minutes. DOPO is adsorbed onto the polyamide 6 fabric through hydrogen bonds, and then further baked at 130-150°C for 30-60 minutes. Since the melting point of DOPO is 117°C, high-temperature baking will melt it and adhere to the surface of the fabric to form a film, thereby obtaining a flame-retardant polyamide 6 fabric with a certain durability.

[0029] The PH bond in DOPO can form a hydrogen bond with the amide group, giving the flame-retardant polyamide 6 a certain water-washing resistance. In addition, the dense film can effectively isolate water from entering, and because DOPO has a certain water repellency, it is difficult to remove DOPO by washing. After film formation, it can form a water-repellent film on the fiber surface, further improving the flame-retardant and water-washing resistance.

[0030] Beneficial Effects

[0031] (1) The DOPO finishing liquid of the present invention has the characteristics of low concentration and high efficiency, and the solvent used is mainly water, which meets the production requirements of enterprises and the trend of green environmental protection;

[0032] (2) The preparation method of a DOPO finishing liquid of the present invention is simple and convenient;

[0033] (3) The flame-retardant polyamide 6 fabric prepared by using the DOPO finishing liquid of the present invention has high fire safety, and the prepared polyamide 6 fabric is a flame-retardant fabric. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is the surface morphology of polyamide 6 fabric after impregnation;

[0035] Figure 2 This is the surface morphology of polyamide 6 fabric after baking. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with specific embodiments. 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 fall within the scope limited by the appended claims of the application equally.

[0037] The detection methods of the relevant properties in the following embodiments are as follows:

[0038] LOI is tested according to ASTMD2863-17;

[0039] The damage length is tested according to ASTMD6413-15;

[0040] The number of droplets is tested according to ASTM D2863-17;

[0041] Water washing was carried out according to AATCC61-2013.

[0042] The manufacturers and brands of the relevant substances in the following examples are as follows:

[0043] DOPO: The manufacturer is Shanghai Dibo Biotechnology Co., Ltd., CAS number is 35948-25-5;

[0044] Polyamide 6 fabric: Manufacturer: Wujiang Fuhua Weaving Co., Ltd., brand name: CNO015003S, weight: 113g / m 2 ; The LOI of the polyamide 6 fabric was 23.0%, the damaged length was 16.0 cm, the number of droplets was 3, and the absorbent cotton was ignited.

[0045] Example 1

[0046] A method for preparing a DOPO finishing liquid comprises the following specific steps: dissolving DOPO in ethanol at a temperature of 60° C., and then adding water thereto to obtain the DOPO finishing liquid; wherein the whole process is assisted by stirring, the stirring speed is 850 r / min, and the stirring time is 25 min.

[0047] The content of DOPO in the finally prepared DOPO finishing liquid is 1 wt %, and the volume ratio of ethanol to water is 1:4; the azeotropic point of the solvent of the DOPO finishing liquid is 86° C.

[0048] An application of a DOPO finishing solution, wherein the pH value of the DOPO finishing solution prepared above is adjusted to 4, a polyamide 6 fabric is immersed in the DOPO finishing solution, and then taken out (the surface morphology of the polyamide 6 fabric after immersion is as follows Figure 1The polyamide 6 fabric was baked at 135°C for 30 min (the surface morphology of the baked polyamide 6 fabric is shown in FIG. Figure 2 As shown), flame retardant polyamide 6 fabric is obtained; wherein, the immersion temperature is 75° C., the immersion time is 55 min, and the immersion bath ratio is 1:30.

[0049] The LOI of the flame retardant polyamide 6 fabric finally obtained was 28%, the damaged length was 14 cm, and the number of droplets was 0; after 20 times of water washing, the LOI of the flame retardant polyamide 6 fabric was 26.4%, the damaged length was 14.9 cm, and the number of droplets was 1.

[0050] Example 2

[0051] A method for preparing a DOPO finishing liquid comprises the following specific steps: dissolving DOPO in isopropanol at a temperature of 80° C., and then adding water thereto to obtain the DOPO finishing liquid; wherein the whole process is assisted by stirring, the stirring speed is 900 r / min, and the stirring time is 20 min.

[0052] The DOPO content in the finally prepared DOPO finishing liquid is 1.5 wt %, and the volume ratio of isopropanol to water is 1:5; the azeotropic point of the solvent of the DOPO finishing liquid is 90°C.

[0053] An application of a DOPO finishing liquid, wherein the pH value of the prepared DOPO finishing liquid is adjusted to 4.2, a polyamide 6 fabric is immersed in the DOPO finishing liquid, and the fabric is baked at 145° C. for 60 minutes to obtain a flame retardant polyamide 6 fabric; wherein the immersion temperature is 80° C., the immersion time is 60 minutes, and the immersion bath ratio is 1:50.

[0054] The LOI of the flame retardant polyamide 6 fabric finally obtained was 28.7%, the damaged length was 13.4 cm, and the number of droplets was 0; after 20 times of water washing, the LOI of the flame retardant polyamide 6 fabric was 27.3%, the damaged length was 14.2 cm, and the number of droplets was 0.

[0055] Example 3

[0056] A method for preparing a DOPO finishing liquid comprises the following specific steps: dissolving DOPO in ethanol at a temperature of 70° C., and then adding water thereto to obtain the DOPO finishing liquid; wherein the whole process is assisted by stirring, the stirring speed is 800 r / min, and the stirring time is 27 min.

[0057] The DOPO content in the finally prepared DOPO finishing liquid is 0.5 wt %, and the volume ratio of ethanol to water is 1:6; the azeotropic point of the solvent of the DOPO finishing liquid is 94° C.

[0058] An application of a DOPO finishing liquid, wherein the pH value of the prepared DOPO finishing liquid is adjusted to 3, a polyamide 6 fabric is immersed in the DOPO finishing liquid, and after being taken out, the fabric is baked at 140° C. for 40 minutes to obtain a flame retardant polyamide 6 fabric; wherein the immersion temperature is 70° C., the immersion time is 65 minutes, and the immersion bath ratio is 1:35.

[0059] The LOI of the flame retardant polyamide 6 fabric finally obtained was 27.1%, the damaged length was 14.8 cm, and the number of droplets was 0; after 20 times of water washing, the LOI of the flame retardant polyamide 6 fabric was 25.8%, the damaged length was 16.2 cm, and the number of droplets was 1.

[0060] Example 4

[0061] A method for preparing a DOPO finishing liquid comprises the following specific steps: dissolving DOPO in isopropanol at 75°C, and then adding water thereto to obtain the DOPO finishing liquid; wherein the whole process is assisted by stirring, the stirring speed is 1000 r / min, and the stirring time is 18 min.

[0062] The DOPO content in the finally prepared DOPO finishing liquid is 2.5 wt %, and the volume ratio of isopropanol to water is 1:5; the azeotropic point of the solvent of the DOPO finishing liquid is 90°C.

[0063] An application of a DOPO finishing liquid, wherein the pH value of the prepared DOPO finishing liquid is adjusted to 5, a polyamide 6 fabric is immersed in the DOPO finishing liquid, and then the fabric is taken out and baked at 150° C. for 45 minutes to obtain a flame retardant polyamide 6 fabric; wherein the immersion temperature is 90° C., the immersion time is 58 minutes, and the immersion bath ratio is 1:40.

[0064] The LOI of the flame retardant polyamide 6 fabric finally obtained was 29.2%, the damaged length was 12.1 cm, and the number of droplets was 0; after 20 times of water washing, the LOI of the flame retardant polyamide 6 fabric was 27.7%, the damaged length was 13.5 cm, and the number of droplets was 1.

[0065] Example 5

[0066] A method for preparing a DOPO finishing liquid comprises the following specific steps: dissolving DOPO in ethanol at a temperature of 65° C., and then adding water thereto to obtain the DOPO finishing liquid; wherein the whole process is assisted by stirring, the stirring speed is 880 r / min, and the stirring time is 15 min.

[0067] The DOPO content in the finally prepared DOPO finishing liquid is 1.8 wt %, and the volume ratio of ethanol to water is 1:4; the azeotropic point of the solvent of the DOPO finishing liquid is 86°C.

[0068] An application of a DOPO finishing liquid, wherein the pH value of the prepared DOPO finishing liquid is adjusted to 3.5, a polyamide 6 fabric is immersed in the DOPO finishing liquid, and then the fabric is taken out and baked at 130° C. for 55 minutes to obtain a flame retardant polyamide 6 fabric; wherein the immersion temperature is 85° C., the immersion time is 50 minutes, and the immersion bath ratio is 1:45.

[0069] The LOI of the flame retardant polyamide 6 fabric finally obtained was 28.5%, the damaged length was 13.7 cm, and the number of droplets was 0; after 20 times of water washing, the LOI of the flame retardant polyamide 6 fabric was 27%, the damaged length was 14.5 cm, and the number of droplets was 0.

[0070] Example 6

[0071] A method for preparing a DOPO finishing liquid comprises the following specific steps: dissolving DOPO in isopropanol at 70°C, and then adding water thereto to obtain the DOPO finishing liquid; wherein the whole process is assisted by stirring, the stirring speed is 950 r / min, and the stirring time is 30 min.

[0072] The DOPO content in the finally prepared DOPO finishing liquid is 2.2 wt %, and the volume ratio of isopropanol to water is 1:6; the azeotropic point of the solvent of the DOPO finishing liquid is 94°C.

[0073] An application of a DOPO finishing liquid, wherein the pH value of the prepared DOPO finishing liquid is adjusted to 3.8, polyamide 6 fabric is immersed in the DOPO finishing liquid, and then the fabric is taken out and baked at 150° C. for 50 minutes to obtain a flame retardant polyamide 6 fabric; wherein the immersion temperature is 88° C., the immersion time is 70 minutes, and the immersion bath ratio is 1:38.

[0074] The LOI of the flame retardant polyamide 6 fabric finally obtained was 29%, the damaged length was 12.6 cm, and the number of droplets was 0; after 20 times of water washing, the LOI of the flame retardant polyamide 6 fabric was 27.5%, the damaged length was 13.8 cm, and the number of droplets was 0.

Claims

1. A DOPO finishing liquid, characterized in that: The invention is composed of DOPO, an alcohol solvent and water, wherein the content of DOPO is 0.5-2.5wt%, the volume ratio of the alcohol solvent to water is 1:4-6, and the alcohol solvent is ethanol or isopropanol; DOPO is dissolved in the DOPO finishing liquid, and the preparation method of the DOPO finishing liquid is as follows: under stirring conditions, DOPO is dissolved in an alcohol solvent, and water is added thereto to obtain the DOPO finishing liquid.

2. A DOPO finishing liquid according to claim 1, characterized in that: The azeotropic point of the solvent of the DOPO finishing solution is 86-90°C.

3. A method for preparing a DOPO finishing liquid as claimed in claim 1 or 2, characterized in that: Under stirring conditions, DOPO is dissolved in an alcohol solvent, and then water is added thereto to obtain a DOPO finishing solution.

4. The method according to claim 3, characterized in that: The stirring temperature is 60-80°C, the stirring time is 15-30min, and the stirring speed is 800-1000r / min.

5. The use of a DOPO finishing liquid as claimed in claim 1 or 2, characterized in that: After the pH value of the DOPO finishing solution is adjusted to 3-5, the polyamide 6 fabric is immersed in it, taken out and baked to obtain the flame-retardant polyamide 6 fabric, wherein the immersion temperature is not higher than the azeotropic point of the DOPO finishing solution.

6. The use according to claim 5, characterized in that: The immersion temperature is 70-90°C, the immersion time is 50-70min, and the immersion bath ratio is 1:30-50.

7. The use according to claim 5, characterized in that: The baking temperature is 130-150°C, and the baking time is 30-60 minutes.

8. The use according to claim 5, characterized in that: The LOI of the flame retardant polyamide 6 fabric is above 27.1%, the damaged length does not exceed 14.8 cm, and the number of droplets is 0; after 20 washes, the LOI of the flame retardant polyamide 6 fabric is above 25.8%, the damaged length does not exceed 16.2 cm, and the number of droplets is 0-1.

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