Modification of low temperature water soluble PVA masterbatch and its application on sea-island fiber

Abstract

The application discloses a modification of low-temperature water-soluble PVA master batch and application thereof on island fibers, and belongs to the field of textiles. In the application, PVA is grafted with phthalic anhydride, and then the grafted modified PVA is mixed with lubricant and antioxidant, so that the thermoplastic melt processing of PVA is realized, and the melting point of the obtained modified PVA master batch is 185-210 DEG C, and the initial thermal decomposition temperature is not lower than 270 DEG C. The island fibers are produced by using the melt processing method, and the production process is free of high-temperature and high-pressure processes and equipment, and free of the discharge of 'three wastes' of waste water, waste gas and waste residue, and has no influence on the environment, and meets the requirements of clean production. The modified PVA is used as the sea component of the island fibers, and can be quickly dissolved in water of 20-40 DEG C, and there is no problem of waste alkali liquor treatment, and the energy consumption and production cost are greatly reduced, and the pollution to the environment is reduced.

Description

Technical Field

[0001] The invention discloses the modification of low-temperature water-soluble PVA masterbatch and the application of the masterbatch to sea-island fibers, belonging to the field of textiles. Background Art

[0002] Sea-island fibers are bicomponent fibers with a sea-island structure, produced by blending or conjugating two thermodynamically incompatible polymers in a specific ratio. Dissolving the sea component produces ultrafine fibers, often achieved through alkali reduction. This requires not only large amounts of caustic soda but also very high temperatures (above 95°C), increasing energy consumption and significantly polluting the environment. Polyvinyl alcohol (PVA) is a green, non-toxic, water-soluble polymer with broad application prospects in the textile fiber, food, pharmaceutical, and papermaking industries. Using PVA as the water-soluble sea phase in sea-island fibers could potentially address the environmental pollution and high energy consumption associated with traditional alkali reduction of sea-island fibers.

[0003] However, PVA's molecular chains contain numerous hydroxyl groups, which readily form intramolecular and intermolecular hydrogen bonds. This abundance of hydrogen bonding results in a close proximity between PVA's melting point and thermal decomposition temperature, making thermoplastic melt spinning difficult. Furthermore, the strong hydrogen bonding results in a regular arrangement of macromolecules and high crystallinity, significantly hindering its water solubility. Furthermore, if the sea component is not stable, it can decompose at high temperatures, making spinning impossible.

[0004] Therefore, it is necessary to prepare a modified PVA that is water-soluble at low temperature and has a high thermal decomposition temperature and can be melt-spun. Summary of the Invention

[0005] [Technical Issues]

[0006] The alkali reduction commonly used in traditional sea-island fibers can cause environmental pollution problems; moreover, the melting point and thermal decomposition temperature of PVA are very close, making it difficult to perform thermoplastic melt spinning processing.

[0007] [Technical solution]

[0008] In order to solve at least one of the above problems, the present invention provides a method for preparing low-temperature water-soluble PVA masterbatch, which effectively solves the pollution problem caused by the use of alkali reduction treatment to prepare sea island fibers in traditional PVA slices, achieves the purpose of composite melt spinning with island phase PET, and at the same time achieves the purpose of dissolving and removing the sea component at a lower water temperature, thereby reducing production costs.

[0009] The first object of the present invention is to provide a method for preparing a low-temperature water-soluble PVA masterbatch, wherein the low-temperature water-soluble PVA masterbatch is a PVA masterbatch that is water-soluble at 20°C to 40°C, and the method comprises the following steps:

[0010] (1) PVA was added to DMSO (dimethyl sulfoxide), and the PVA was dissolved by heating and stirring to obtain a homogeneous PVA solution;

[0011] (2) adding phthalic anhydride solution to the above PVA solution and stirring evenly, and adding triethylamine after the reaction to continue the reaction to obtain a reaction solution with uniform hue;

[0012] (3) The reaction solution obtained in step (2) is cooled to room temperature, and then poured into anhydrous ethanol for sedimentation to obtain a grafted product, and the grafted product is further washed with anhydrous ethanol for 3 to 5 times, and then dried and crushed to obtain a powdered grafted product with a particle size of 300 to 500 mesh, and then mixed with a lubricant and an antioxidant, melt-extruded and pelletized to obtain a modified PVA masterbatch.

[0013] In one embodiment of the present invention, the temperature of the heating, stirring and dissolving in step (1) is 85-95°C.

[0014] In one embodiment of the present invention, the time for heating, stirring and dissolving in step (1) is 5 to 6 hours.

[0015] In one embodiment of the present invention, the concentration of the PVA solution in step (2) is 60-80 mg / mL.

[0016] In one embodiment of the present invention, the phthalic anhydride solution in step (2) is a DMSO solution of phthalic anhydride with a concentration of 0.1 to 0.2 g / mL.

[0017] In one embodiment of the present invention, the volume ratio of the PVA solution to the phthalic anhydride solution in step (2) is 75-80:5-15.

[0018] In one embodiment of the present invention, the reaction time of adding the phthalic anhydride solution to the PVA solution in step (2) is 30 to 40 minutes.

[0019] In one embodiment of the present invention, the mass ratio of triethylamine to PVA in step (2) is 0.1 to 0.9:5.

[0020] In one embodiment of the present invention, triethylamine is added in step (2) and the reaction is carried out for 5 to 6 hours.

[0021] In one embodiment of the present invention, the volume ratio of the mixed solution in step (3) to anhydrous ethanol is 1:5.

[0022] In one embodiment of the present invention, the lubricant in step (3) is calcium stearate.

[0023] In one embodiment of the present invention, the antioxidant in step (3) is antioxidant B225.

[0024] In one embodiment of the present invention, the drying in step (3) is vacuum drying at 60-80° C. for 20-30 hours.

[0025] In one embodiment of the present invention, the mass ratio of the powdered graft product in step (3) to the lubricant and antioxidant is 100:3-4:1-2.

[0026] The present invention also uses a low-temperature water-soluble PVA masterbatch prepared by the above method.

[0027] In one embodiment of the present invention, the low-temperature water-soluble PVA masterbatch can be dissolved in water at 20°C to 40°C.

[0028] A second object of the present invention is to provide a method for preparing sea-island fibers from a low-temperature water-soluble PVA masterbatch, comprising the following steps:

[0029] The low-temperature water-soluble PVA masterbatch of the present invention is used as the sea component, and PET is used as the island component; the sea component and the island component are added to the hopper of a twin-screw extruder in a mass ratio of 20-40:60-80 for composite spinning to prepare low-temperature water-soluble sea island fibers.

[0030] In one embodiment of the present invention, the composite spinning specifically includes: melt spinning, side blowing cooling, oiling, winding, online stretching, and heat setting; wherein the temperature of the modified PVA masterbatch melt spinning is 165-195°C, and the temperature of the PET melt spinning is 280-300°C; the side blowing temperature is 18-20°C, the side blowing speed is 0.4-0.7 m / s, and the relative humidity of the cooling air is 55-70%; the winding speed of the spun yarn in the winding step is 30-100 m / min; the spinning speed is 3000-4000 m / min; the heat setting temperature is 75-125°C, and the online stretching multiple is 8-20 times.

[0031] In one embodiment of the present invention, the number of holes of the spinneret used in the composite spinning is 24 to 96, and each hole has 24 to 37 islands.

[0032] The present invention provides a method for preparing sea-island fibers from the low-temperature water-soluble PVA masterbatch, wherein the method prepares a low-temperature water-soluble sea-island fiber.

[0033] The third object of the present invention is to provide a method for preparing PET ultrafine fibers, wherein the method comprises placing the above-mentioned low-temperature water-soluble sea island fibers in warm water for treatment, dissolving PVA, and obtaining PET ultrafine fibers; wherein the specific parameters for the treatment in warm water are: a bath ratio of 25 to 35:1, a water temperature of 20 to 40°C, and a dissolution time of 30 to 75s.

[0034] The PET ultrafine fiber prepared by the preparation method of the PET ultrafine fiber.

[0035] [Advantages]

[0036] The application grafts PVA with phthalic anhydride, then mixes the modified PVA with lubricant and antioxidant, realizes the thermoplastic melt processing of PVA, and the melting point of the modified PVA master batch is 185-210 DEG C, and the initial thermal decomposition temperature is not less than 270 DEG C. The sea-island fiber is produced by melt processing, and the production process is free of high-temperature and high-pressure processes and equipment, and free of "three wastes" discharge of waste water, waste gas and waste residue, and has no influence on the environment, and meets the requirements of clean production. The modified PVA is used as the sea component of the sea-island fiber, and can be quickly dissolved in water of 20-40 DEG C, and there is no problem of waste lye treatment, greatly reduces the energy consumption and production cost, and reduces the pollution to the environment. DETAILED DESCRIPTION

[0037] The preferred embodiments of the application are described below, and it should be understood that the embodiments are used to better explain the application, and are not used to limit the application.

[0038] The PVA in the following examples is PVA1788, which is purchased from Macklin; the antioxidant B225 is purchased from Macklin; and the remaining reagents can be obtained on the market.

[0039] Test method:

[0040] Melting point test: differential scanning calorimeter (DSC) is used for determination.

[0041] Initial thermal decomposition temperature test: thermogravimetric analyzer (TG) is used for determination.

[0042] Breaking strength and elongation at break test method: according to the national standard "GB / T14344-2008 Chemical Fiber Filament Tensile Property Test Method", the clamping distance is 500 mm, the tensile speed is 500 mm / min, and the pre-tension is 0.05 cN / dtex.

[0043] Fineness test method: according to the single method in the national standard "GB / T14343-2008 Chemical Fiber Filament Linear Density Test Method", the length and weight are tested, the linear density of the ultrafine fiber multifilament is calculated, and then the linear density of the single ultrafine fiber is obtained by dividing the linear density of the multifilament by the number of fibers in the multifilament.

[0044] Example 1

[0045] A method for preparing modified PVA master batch, comprising the following steps:

[0046] (1) 5 g of PVA was added to 80 mL of DMSO and dissolved by stirring at 60°C for 5 h to obtain a homogeneous PVA solution.

[0047] (2) Add 10 mL of 0.15 g / mL phthalic anhydride solution to the PVA solution of step (1), stir evenly, react for 30 min, then add 0.5 g of triethylamine and continue the reaction for 5 h to obtain a reaction solution with uniform hue;

[0048] (3) The reaction solution obtained in step (2) is cooled to room temperature, vacuum-dried at 80° C. for 24 h, and then poured into 500 ml of anhydrous ethanol for sedimentation to obtain a grafted product. The grafted product is further washed with anhydrous ethanol for 3 to 5 times, placed in a vacuum oven for drying, and then crushed to obtain a powdered grafted product with a particle size of 300 to 500 mesh. The powdered grafted product is then mixed with lubricant calcium stearate and antioxidant B225 in a mass ratio of 100:3:1, and then melt-extruded and pelletized through a twin-screw extruder to obtain a modified PVA masterbatch.

[0049] Example 2

[0050] This example investigates the effect of phthalic anhydride dosage on the melting point, thermal decomposition temperature, and water solubility of PVA. The amount of phthalic anhydride used in Example 1 was adjusted, while all other conditions remained the same. The modified PVA masterbatch shown in the table below was dissolved at 25°C, with a masterbatch mass of 0.2 g and 200 mL of water.

[0051] Table 1 Test results of Example 2

[0052] Amount of phthalic anhydride Melting point Tm Initial thermal decomposition temperature Td Td-Tm Dissolution time 4mL 208.7℃ 275.4℃ 66.7℃ >10min 6mL 205.4℃ 273.5℃ 68.1℃ 7-8 minutes 8mL 196.5℃ 270.7℃ 74.2℃ 4-5 minutes 10 mL (Example 1) 185.3℃ 276.2℃ 90.9℃ 3-4 minutes 12mL 188.8℃ 277.5℃ 88.7℃ 4-5 minutes 14mL 190.6℃ 278.2℃ 87.6℃ 5-6 minutes 16mL 185.0℃ 270.7℃ 85.7℃ 5-6 minutes 18mL 180.2℃ 263.2℃ 83.0℃ 7-8 minutes 20mL 175.3℃ 256.5℃ 81.2℃ Insoluble

[0053] As can be seen from the table, as the amount of phthalic anhydride increases, the melting point and thermal decomposition temperature first decrease, then increase, and then decrease again. This is mainly due to the crystallinity and thermal stability of the benzene ring. When phthalic anhydride is grafted onto PVA, the crystallinity of the PVA decreases, thereby reducing the melting point. However, since the grafting rate is low when the amount of phthalic anhydride is relatively low, the dominant factor at this time is the crystallinity. Therefore, when the phthalic anhydride content is low, the melting point decreases and the thermal stability decreases as the phthalic anhydride content increases. When the phthalic anhydride content exceeds a certain level, the grafting rate increases, and the thermal stability of the benzene ring begins to play a certain dominant role. As the phthalic anhydride content increases, both the melting point and thermal stability increase. When the content reaches a certain level, the grafting rate continues to increase until it stops. However, at this point, due to the large number of benzene rings and ester groups on the PVA molecular chain, the degree of reduction in the crystallinity of the PVA is greater than the thermal stability of the benzene rings. The presence of a large number of ester groups also reduces its water solubility. It can be seen from the table that when the amount of phthalic anhydride is 10 mL, the melt processing window of the modified PVA is the largest, and it is found that the masterbatch can be quickly dissolved within 3 to 4 minutes.

[0054] Example 3

[0055] Referring to Example 1, the amount of triethylamine was adjusted according to Table 1, and the other conditions were the same as in Example 1 to obtain modified PVA masterbatch. The properties of the modified PVA masterbatch obtained are shown in Table 1.

[0056] Table 1: Comparison of triethylamine addition amount and properties of modified PVA masterbatch

[0057] The amount of triethylamine Melting point Tm Initial thermal decomposition temperature Td Td-Tm Dissolution time 0 201.2℃ 272.2℃ 71℃ 7-8 minutes 0.1g 194.5℃ 271.6℃ 76.2℃ 6-7 minutes 0.2g 193.1℃ 270.3℃ 77.2 6-7 minutes 0.3g 190.2℃ 268.2℃ 78.0 5-6 minutes 0.4g 188.3℃ 274.3℃ 79.9 4-5 minutes 0.5g (Example 1) 185.3℃ 276.2℃ 90.9℃ 3-4 minutes 0.6g 185.4℃ 274.2℃ 88.8 3-4 minutes 0.7g 184.7℃ 270.3℃ 85.6 6-7 minutes 0.8g 182.6℃ 266.2℃ 83.6 Insoluble 0.9g 182.4℃ 267.1℃ 84.7 Insoluble

[0058] It was found through testing that the melting point of the modified PVA obtained when the system did not contain triethylamine did not decrease much, and the water solubility was not good, indicating that the grafting rate was low at this time, and triethylamine played the role of a catalyst. Initially, as the content of triethylamine increased, the melting point of the system gradually decreased, the thermal stability decreased, and the dissolution time gradually decreased, indicating that the grafting rate was increasing and the crystallinity was decreasing. When the content of triethylamine reached 0.4 g, the melting point of the system continued to decrease and eventually stabilized, the thermal stability first increased and then decreased, and the dissolution time increased. This indicates that when the catalyst content reaches 0.4 g, the grafting rate of the system is still increasing, and at this time the thermal stability of the benzene ring begins to play a role. When the catalyst is 0.5 g, the thermal stability of the system reaches a maximum, and then as the grafting rate increases, the degree of decrease in the crystallinity of PVA is greater than the thermal stability of the benzene ring, and the thermal stability becomes worse. However, when the amount of catalyst reaches a certain degree, the grafting rate reaches a maximum, and further increasing the amount of catalyst does not increase the grafting rate, so the melting point and thermal stability tend to be stable. After reaching the maximum grafting rate, a large number of benzene rings and ester groups exist in the system, making the water solubility of the system worse.

[0059] Comparative Example 1

[0060] In Example 1, phthalic anhydride was replaced by succinic anhydride, and the other conditions were the same as in Example 1 to obtain modified PVA masterbatch.

[0061] Comparative Example 2

[0062] In Example 1, phthalic anhydride was replaced by diphenyl tetracarboxylic dianhydride, and the other conditions were the same as in Example 1 to obtain modified PVA masterbatch.

[0063] The modified PVA obtained in Example 1 and Comparative Examples 1-2 was tested for performance, and the test results are shown in Table 1 below.

[0064] Table 2: Test results of Example 1 and Comparative Examples 1 and 2

[0065] example Melting point Tm Initial thermal decomposition temperature Td Td-Tm Dissolution time Example 1 185.3℃ 276.2℃ 90.9℃ 3-4 minutes Comparative Example 1 195.4℃ 264.1℃ 68.7℃ 4-5 minutes Comparative Example 2 189.1℃ 265.2℃ 76.1℃ 6-7 minutes

[0066] After testing, the thermal decomposition temperature of the modified PVA masterbatch obtained in Control Example 1 is lower, indicating that the grafting of succinic anhydride onto PVA does not increase the thermal stability of PVA, which is not conducive to the melt spinning processing of PVA; the thermal decomposition temperature of the modified PVA masterbatch obtained in Control Example 2 is low, which can be explained by the fact that the molecules of biphenyltetracarboxylic dianhydride are larger and have greater steric hindrance, making it difficult to undergo grafting reaction with PVA. Some biphenyltetracarboxylic dianhydride molecules are dispersed in the system, which reduces the crystallinity of the system, and reduces the melting point and thermal decomposition temperature. In addition, biphenyltetracarboxylic dianhydride has more benzene rings than phthalic anhydride, which makes the water solubility of the system worse.

[0067] Example 3

[0068] A method for preparing low-temperature water-soluble sea-island fibers comprises the following steps:

[0069] The modified PVA masterbatch prepared in Example 1 was used as the sea component, and PET was used as the island component; the sea component and the island component were added to the hopper of a screw extruder in a mass ratio of 30:70 for composite spinning to prepare low-temperature water-soluble sea island fibers.

[0070] The composite spinning process specifically includes melt spinning, side-blowing cooling, oiling, winding, online stretching, and heat setting. The melt spinning temperature for the modified PVA masterbatch is 186°C, and the melt spinning temperature for PET is 295°C. The side-blowing temperature is 20°C, the speed is 0.4 m / s, and the relative humidity of the cooling air is 68%. The winding speed of the spun yarn in the winding step is 50 m / min; the spinning speed is 3000 m / min; the heat setting temperature is 115°C, and the online stretching ratio is 10 times. The spinneret used in the composite spinning process has 56 holes, with 30 islands per hole.

[0071] The obtained sea-island fiber was subjected to a performance test, and the results showed that the fineness was 3.42 dtex, the breaking strength was 6.4 cN / dtex, and the breaking elongation was 10.8%.

[0072] Example 4

[0073] The sea-island fibers prepared in Example 3 were soaked in water at a bath ratio of 35:1 and a temperature of 25° C. for 45 to 60 seconds to completely dissolve the sea component PVA and obtain PET ultrafine fibers with a fineness of 0.45 dtex.

Claims

1. A method for preparing low-temperature water-soluble PVA masterbatch, characterized in that: The steps include: (1) Add PVA to DMSO, heat and stir to dissolve PVA to obtain a homogeneous PVA solution; (2) Add phthalic anhydride solution to the above PVA solution and stir evenly. After the reaction, add triethylamine and continue the reaction to obtain a reaction solution with a uniform color. The concentration of the PVA solution is 60-80 mg / mL. The phthalic anhydride solution is a DMSO solution of phthalic anhydride with a concentration of 0.1-0.2 g / mL; the volume ratio of the PVA solution to the phthalic anhydride solution is (75-80):(5-15); the mass ratio of triethylamine to PVA is 0.4-0.7:5; after adding triethylamine, the reaction is carried out for 5-6 hours; (3) The reaction solution obtained in step (2) is cooled to room temperature, and then poured into anhydrous ethanol for sedimentation to obtain a grafted product, and the grafted product is further washed with anhydrous ethanol for 3 to 5 times, and then dried and crushed to obtain a powdered grafted product with a particle size of 300 to 500 mesh, and then mixed with a lubricant and an antioxidant, melt-extruded and pelletized to obtain a modified PVA masterbatch with an initial thermal decomposition temperature of not less than 270°C; The low temperature is 20°C to 40°C.

2. The low-temperature water-soluble PVA masterbatch obtained according to the method of claim 1.

3. A method for preparing sea-island fibers using low-temperature water-soluble PVA masterbatch, characterized in that: The steps include: The low-temperature water-soluble PVA masterbatch described in claim 2 is used as the sea component, and PET is used as the island component; the sea component and the island component are added to the hopper of a twin-screw extruder in a mass ratio of (20~40): (60~80) for composite spinning to prepare low-temperature water-soluble sea island fibers; the number of holes in the spinneret used in the composite spinning is 24~96 holes, and 24~37 islands per hole.

4. The low-temperature water-soluble sea-island fiber prepared according to the method of claim 3.

5. A method for preparing PET ultrafine fibers, characterized in that: The method is to place the low-temperature water-soluble sea island fiber described in claim 4 in warm water for treatment, dissolve the PVA, and obtain PET ultrafine fibers; the specific parameters of the treatment in warm water are: bath ratio of 25~35:1, water temperature of 20~40℃, and dissolution time of 30~75s.

6. PET ultrafine fiber prepared by the method according to claim 5.