A kind of low melting point ultra short fiber and preparation method thereof

Abstract

This case involves a low-melting point ultra-short fiber and its preparation method, which is an ES composite fiber, including a skin layer and a core layer. The material of the skin layer includes: PE, modified masterbatch; the material of the core layer is PE; the modified masterbatch first modifies the mesoporous silica by amino; the hyperbranched polymer chain containing ester groups and carboxyl groups is prepared by active free radical polymerization; the two are grafted to form an organic whole; and then grafted with PE and maleic anhydride in a reactive twin-screw extruder under the initiation of an initiator. This application uses polyolefin as the main raw material to produce low-melting point ultra-short fibers. Compared with polyester, the cost is effectively controlled and the softness is effectively improved; modified masterbatch is added to the skin structure to weaken the interaction between PE molecular chains, weaken the interaction between crystals, and effectively reduce the melting point of the skin; the production process is smooth, and the phenomena of sizing, floating, and winding are all within a controllable range.

Description

Technical Field

[0001] The invention relates to the field of composite fibers, in particular to a low-melting-point ultra-short fiber and a preparation method thereof. Background Art

[0002] The variety of fiber forms and cut lengths of ultra-short fibers enable them to be widely used in many fields, such as sanitary products, non-woven fabrics, papermaking, etc. Different types of ultra-short fibers are used for different application scenarios, and there are many varieties, including polyester ultra-short fibers, polypropylene ultra-short fibers, aramid ultra-short fibers, glass fibers, ES composite fibers, etc.

[0003] In the production of some non-woven fabrics and dust-free papers, fibers are required to have a low melting point. Usually, polyester composite fibers are used as the main fibers. Polyester with a low melting point, such as PET, is used as the skin structure. The melting point of the skin is lower than that of the core layer, and it has the characteristics of low hot-melt bonding temperature and rapid bonding. However, this type of low-melting-point polyester composite fiber contains isophthalic acid, which is high in cost and has high rigidity, poor spinnability, and poor fiber forming, which leads to relatively poor softness and is limited in its application in non-woven fabrics. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention adopts polyolefin as the main raw material to prepare an ultra-short composite fiber with a low melting point.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A low melting point ultra-short fiber, which is an ES composite fiber, comprises a skin layer and a core layer, wherein the material of the skin layer comprises: PE and modified masterbatch; the material of the core layer is PE;

[0007] Wherein, the preparation process of the modified masterbatch is as follows:

[0008] S1, mesoporous silica was dispersed in a methanesulfonic acid aqueous solution, heated to 90 °C, stirred and refluxed overnight, cooled, washed and filtered, then mixed evenly with γ-aminopropyltrimethoxysilane in water, heated to 50 °C, stirred for 24 h, cooled to room temperature, filtered, rinsed with ethanol, and dried to obtain amino mesoporous silica;

[0009] S2, synthesizing hyperbranched polymers through RAFT system using vinyl acetate, ethyl acrylate and acrylic acid as monomers, AIBN as initiator and xanthate containing terminal double bonds as chain transfer agent;

[0010] S3, dispersing and dissolving the products of step S1 and step S2 in tetrahydrofuran respectively, then mixing the two, stirring and refluxing overnight under a nitrogen atmosphere, then centrifuging, washing the obtained product with ethanol and water, and vacuum drying to obtain hyperbranched polymer mesoporous silica;

[0011] S4, dissolving maleic anhydride and initiator in tetrahydrofuran, then adding hyperbranched polymer mesoporous silica and PE and mixing evenly, extruding through a reactive twin-screw extruder, cutting into pellets and drying to obtain the product.

[0012] In the above-mentioned process of preparing the modified masterbatch, firstly, the mesoporous silica is amino-modified to form amino active sites on its surface, which can be subjected to amidation reaction, etc.; secondly, the hyperbranched polymer chain containing ester and carboxyl groups is prepared by active free radical polymerization, and the amino-modified mesoporous silica is used as a template to form an organic whole by grafting reaction on its surface; then, the organic whole is grafted with PE in a reactive twin-screw extruder under the initiation of an initiator with maleic anhydride, forming a modified masterbatch with PE as a carrier, which has a mesoporous and three-dimensional network structure. It can reduce the intermolecular force of PE, reduce the interaction force between crystals, reduce the crystallinity, and thus reduce the melting point. The modified masterbatch mixed with PE has good dispersibility and compositeness, avoiding the occurrence of floating silk and broken silk in the production process caused by uneven mixing, as well as the occurrence of slurry in the post-spinning process.

[0013] Furthermore, the mass ratio of the skin layer to the core layer is 40-45:60-55; the modified masterbatch accounts for 10-20 wt% in the skin layer.

[0014] Furthermore, the mesoporous silica is prepared by a sol-gel method using tetraethyl orthosilicate as a silicon source and P123 as a template.

[0015] Furthermore, in step S1, the mass volume ratio of mesoporous silica to γ-aminopropyltrimethoxysilane is 1:1.

[0016] Furthermore, in step S2, the xanthate containing a terminal double bond is (2-ethoxydithioate) vinyl acetate; the molar ratio of vinyl acetate, butyl acrylate, acrylic acid, AIBN and the xanthate containing a terminal double bond is 100:10~50:50~90:0.5:1.

[0017] Furthermore, in step S3, the dosage ratio of the products of step S1 and step S2 is 0.05-0.1:1.

[0018] Furthermore, in step S4, the mass ratio of maleic anhydride, initiator, hyperbranched polymer mesoporous silica and PE is 5-10:0.5-1:1-5:90.

[0019] The present invention further provides a method for preparing the above low melting point ultrashort fibers, comprising the following steps:

[0020] Pre-spinning process: the raw materials of the skin layer and the core layer are respectively fed into two screw extruders through two feeding hoppers to be melted and extruded into melts. After filtering, they are precisely metered by metering pumps and enter the spinning box, and then come to the spinning assembly to form raw silk with skin-core structure;

[0021] Post-spinning process: The raw silk from the front spinning is bundled and passed through an oil immersion tank, a steam preheating box, a water bath, three drafting, an oiling roller, a crimping machine, a relaxation heat setting machine, and cut into ultra-short fibers of the required size.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: the present application adopts polyolefin as the main raw material to produce low-melting-point ultra-short fibers, and the cost is effectively controlled and the softness is effectively improved compared with polyester; a modified masterbatch is added to the cortical structure, which contains mesoporous silica and hyperbranched polymer chains, and has a mesoporous and three-dimensional network structure, which reduces the entanglement of intermolecular chains, weakens the interaction force between PE molecular chains, weakens the interaction force between crystals, and effectively reduces the melting point of the cortex; the production process is smooth, and there are fewer slurry, floating filaments, and roller winding phenomena. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Embodiment: A low melting point ultrashort fiber is an ES composite fiber, comprising a skin layer and a core layer, wherein the material of the skin layer comprises: PE and modified masterbatch; the material of the core layer is PE; the mass ratio of the skin layer to the core layer is 40~45:60~55; the modified masterbatch accounts for 10~20wt% in the skin layer.

[0026] Wherein, the preparation process of the modified masterbatch is as follows:

[0027] S1. Dissolve 2g of template P123 in hydrochloric acid solution, and finally add 4.5g of ethyl orthosilicate dropwise, stir at 40°C to form an organosilicon sol, and then stand at 90°C for 24h, centrifuge and vacuum dry to obtain mesoporous silica;

[0028] 2g of mesoporous silica was dispersed in 10ml of 5% methanesulfonic acid aqueous solution, heated to 90℃, stirred and refluxed overnight, cooled, washed and filtered, then mixed evenly with 2ml of γ-aminopropyltrimethoxysilane in water, heated to 50℃, stirred for 24h, cooled to room temperature, filtered, rinsed with ethanol, and dried to obtain amino-modified mesoporous silica;

[0029] S2, synthesizing a hyperbranched polymer through a RAFT system using 1 mol of vinyl acetate, 200 mmol of ethyl acrylate and 800 mmol of acrylic acid as monomers, 5 mmol of AIBN as an initiator, and 10 mmol of xanthate containing a terminal double bond ((2-ethoxydithioate) vinyl acetate, prepared by referring to patent 201010223709.X) as a chain transfer agent;

[0030] S3, dispersing and dissolving the products of step S1 and step S2 in tetrahydrofuran respectively, then mixing the two, stirring and refluxing overnight under a nitrogen atmosphere, then centrifuging, washing the obtained product with ethanol and water, and vacuum drying to obtain hyperbranched polymer mesoporous silica;

[0031] S4, dissolve maleic anhydride and initiator in tetrahydrofuran, then add hyperbranched polymer mesoporous silica and PE and mix evenly, extrude through a reactive twin-screw extruder, cut into pellets and dry. (The mass ratio of maleic anhydride, initiator, hyperbranched polymer mesoporous silica and PE is 5~10:0.5~1:1~5:90)

[0032] When the other conditions remain unchanged, the mass ratio in step S4 is adjusted to obtain the following modified masterbatch.

[0033] Sample 1: The mass ratio of maleic anhydride, initiator, hyperbranched polymer mesoporous silica and PE is 5:0.5:2:90;

[0034] Sample 2: The mass ratio of maleic anhydride, initiator, hyperbranched polymer mesoporous silica and PE is 7:0.6:3:90;

[0035] Sample 3: The mass ratio of maleic anhydride, initiator, hyperbranched polymer mesoporous silica and PE is 8:0.8:5:90;

[0036] Sample 4: The mass ratio of maleic anhydride, initiator, hyperbranched polymer mesoporous silica and PE is 8:0.6:0:90.

[0037] Pre-spinning process: the raw materials of the skin layer and the core layer are respectively fed into two screw extruders through two feeding hoppers to be melted and extruded into a melt. After filtering, they are precisely metered into the spinning box by a metering pump and come to the spinning assembly to form a raw fiber with a skin-core structure; the mass ratio of the skin layer and the core layer is 40:60; the modified masterbatch accounts for 10 wt% in the skin layer.

[0038] Post-spinning process: The raw silk from the front spinning is bundled and passed through an oil immersion tank, a steam preheating box, a water bath, three drafting, an oiling roller, a crimping machine, a relaxation heat setting machine, and cut into ultra-short fibers of the required size.

[0039] Short fibers were prepared using different masterbatch bases and different ratios, and the undesirable phenomena such as roller winding that occurred during the preparation process were recorded and recorded in Table 1.

[0040] Table 1

[0041]

[0042] It can be seen from Table 1 that with the increase of the proportion of masterbatch added, the number of rollers increases, and the number of floating filaments and sizing filaments also increases, but the overall production situation is within an acceptable range. The performance of the short fibers prepared with 15% masterbatch addition is tested, and the results are recorded in Table 2.

[0043] Table 2

[0044]

[0045] As can be seen from Table 2, the melting point of the cortex can be effectively reduced by adding the modified masterbatch. Compared with the cortex melting point of 127°C of traditional fibers, the cortex melting point of the present application can be reduced to 109°C, which can meet higher test requirements.

[0046] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A low melting point ultra short fiber, characterized in that: It is an ES composite fiber, including a skin layer and a core layer, wherein the material of the skin layer includes: PE and modified masterbatch; the material of the core layer is PE; Wherein, the preparation process of the modified masterbatch is as follows: S1, mesoporous silica is dispersed in a methanesulfonic acid aqueous solution, heated to 90°C, stirred and refluxed overnight, cooled, washed and filtered, then mixed evenly with γ-aminopropyltrimethoxysilane in water, heated to 50°C, stirred for 24h, cooled to room temperature, filtered, rinsed with ethanol, and dried to obtain amino mesoporous silica; S2, synthesizing hyperbranched polymers through RAFT system using vinyl acetate, ethyl acrylate and acrylic acid as monomers, AIBN as initiator and xanthate containing terminal double bonds as chain transfer agent; S3, dispersing and dissolving the products of step S1 and step S2 in tetrahydrofuran respectively, then mixing the two, stirring and refluxing overnight under a nitrogen atmosphere, then centrifuging, washing the obtained product with ethanol and water, and vacuum drying to obtain hyperbranched polymer mesoporous silica; S4, dissolving maleic anhydride and initiator in tetrahydrofuran, then adding hyperbranched polymer mesoporous silica and PE and mixing evenly, extruding through a reactive twin-screw extruder, cutting into pellets and drying to obtain the product.

2. The low melting point ultra short fiber according to claim 1, characterized in that: The mass ratio of the skin layer to the core layer is 40-45:60-55; the modified masterbatch accounts for 10-20wt% in the skin layer.

3. The low melting point ultra short fiber according to claim 1, characterized in that: The mesoporous silica is prepared by a sol-gel method using tetraethyl orthosilicate as a silicon source and P123 as a template.

4. The low melting point ultra short fiber according to claim 1, characterized in that: In the step S1, the mass volume ratio of mesoporous silica to γ-aminopropyltrimethoxysilane is 1:

1.

5. The low melting point ultra short fiber according to claim 1, characterized in that: In the step S2, the xanthate containing a terminal double bond is (2-ethoxydithioate) vinyl acetate; the molar ratio of vinyl acetate, butyl acrylate, acrylic acid, AIBN and the xanthate containing a terminal double bond is 100:10-50:50-90:0.5:

1.

6. The low melting point ultra short fiber according to claim 1, characterized in that: In the step S3, the dosage ratio of the product of step S1 to that of the product of step S2 is 0.05-0.1:

1.

7. The low melting point ultra short fiber according to claim 1, characterized in that: In the step S4, the mass ratio of maleic anhydride, initiator, hyperbranched polymer mesoporous silica and PE is 5-10:0.5-1:1-5:

90.

8. The method for preparing low-melting-point ultra-short fibers according to any one of claims 1 to 7, characterized in that: The steps include: Pre-spinning process: the raw materials of the skin layer and the core layer are respectively fed into two screw extruders through two feeding hoppers to be melted and extruded into melts. After filtering, they are precisely metered by metering pumps and enter the spinning box, and then come to the spinning assembly to form raw silk with skin-core structure; Post-spinning process: The raw silk from the front spinning is bundled and passed through an oil immersion tank, a steam preheating box, a water bath, three drafting, an oiling roller, a crimping machine, a relaxation heat setting machine, and cut into ultra-short fibers of the required size.

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