Polyester and pre-oxidized filament mixed non-woven fabric, and preparation method and application thereof

Abstract

The present application belongs to the technical field of non-woven fabric preparation, and particularly relates to a polyester and pre-oxidized yarn mixed non-woven fabric, a preparation method thereof and application. According to the weight percentage, the mixed non-woven fabric comprises the following components: 15%-70% of polyester and 30%-85% of pre-oxidized yarn. The present application provides a polyester and pre-oxidized yarn mixed non-woven fabric, a preparation method thereof and application of the non-woven fabric in carbon fiber preparation. By reasonably selecting the proportion of polyester and pre-oxidized yarn (15%-70% of polyester and 30%-85% of pre-oxidized yarn) and adopting specific opening, carding, laying and needling processes, technical difficulties such as easy breaking, uneven distribution and poor entanglement of the mixed fibers in the processing process are successfully solved.

Description

Technical Field

[0001] This invention belongs to the field of nonwoven fabric preparation technology, specifically relating to a polyester and pre-oxidized yarn blended nonwoven fabric, its preparation method, and its application. Background Technology

[0002] Carbon fiber, as an advanced composite material with high strength, high modulus, and low density, has broad application prospects in aerospace, automotive manufacturing, sporting goods, and electronic equipment. With the increasing demand for lightweight and high-performance materials, the research and development of carbon fiber and its precursor materials has become one of the important directions in materials science.

[0003] Currently, the main precursor for carbon fiber is polyacrylonitrile (PAN)-based fiber, and its preparation process typically involves multiple steps such as precursor fiber preparation, pre-oxidation, and carbonization. Among these, nonwoven fabric structures are increasingly being used in carbon fiber precursor preparation due to their high structural design flexibility, high production efficiency, and relatively low cost. However, the single PAN fiber or its pre-oxidized filament used in traditional methods suffers from poor processing performance, insufficient strength, and complex processes during web formation, limiting their application in large-scale industrial production.

[0004] Polyester fiber is widely used in the textile industry due to its excellent mechanical properties, good thermal stability, and low cost. However, polyester itself is difficult to use directly in the preparation of carbon fiber. How to effectively combine polyester with pre-oxidized yarn, and achieve efficient molding of blended nonwoven fabrics through reasonable proportioning and process control, and further use them in the preparation of carbon fiber, is an important issue in current technological development.

[0005] Therefore, this invention is proposed. Summary of the Invention

[0006] To address the technical problems existing in the prior art, this invention provides a nonwoven fabric made of polyester and pre-oxidized yarn, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A polyester and pre-oxidized yarn blended nonwoven fabric, comprising, by weight percentage, 15%-70% polyester and 30%-85% pre-oxidized yarn.

[0009] Furthermore, by weight percentage, the blended nonwoven fabric comprises the following components: 15% polyester and 85% pre-oxidized yarn.

[0010] A method for preparing a nonwoven fabric blended with polyester and pre-oxidized yarn includes the following steps:

[0011] (1) Raw material preparation

[0012] Prepare polyester and pre-oxidized yarn according to the above component ratio and mix them together;

[0013] (2) Opening process

[0014] The above-mentioned mixed raw materials are fed into the opening machine. The speed of the opening machine beater is adjusted to 650-800 rpm. The opening gap of the opening machine is adjusted according to the fiber length, linear density and crimp to make the short fibers open gently.

[0015] (3) Combing process

[0016] After opening, the short fibers are fed into the carding machine. The conventional speed ratio of the carding machine is adjusted to 15-18, the cylinder speed is 650-800 rpm, the distance between the cylinder and the doffer is 0.25-0.35 mm, and the distance between the transfer rollers is 0.1 mm.

[0017] (4) Mesh laying process

[0018] The combed fiber web is fed into the web laying machine. The web laying speed of the web laying machine is controlled below 40m / min, and the stroke of the web laying machine trolley is adjusted to stretch to 100-120%.

[0019] (5) Needle Puncture Technique

[0020] After the fiber web is laid, a multi-stage needle punching process is used to gradually increase the degree of entanglement.

[0021] In step (1), after the polyester and pre-oxidized yarn are mixed, the humidity in the workshop is controlled at 40%-70%.

[0022] The specific process of step (2) is as follows: for long fibers with a fiber length of more than 51 mm, a large gap of 8-12 mm is used; for short fibers with a fiber length of less than 38 mm, a small gap of 5-8 mm is used; for coarse denier fibers with a linear density of more than 3D, a large gap of 8-12 mm is used; for fine denier fibers with a linear density of less than 3D, a small gap of 5-8 mm is used; for crimp numbers of 15-30, a large gap of 8-12 mm is used; and for crimp numbers of 30-50, a small gap of 5-8 mm is used.

[0023] In step (4), the travel of the web laying machine trolley is adjusted to be stretched to 100-110%.

[0024] The multi-level acupuncture process in step (5) includes three levels: pre-puncture, main puncture, and fine puncture. The pre-puncture needles are size 36-38, and the acupuncture density is 60-80 needles / m. 2 The needle depth is 6-8mm; the main piercing needle is size 40-42, and the needle density is 150-300 needles / m². 2The needle depth is 3-6mm; the needle used for precision puncture is size 42-45, and the needle density is 400-600 needles / m². 2 The needle depth is 0.5-1mm.

[0025] The needle angles for pre-puncture, main puncture, and fine puncture are all 15°-20°.

[0026] An application of preparing carbon fiber using a blend of polyester and pre-oxidized yarn nonwoven fabric includes the following steps in sequence: nonwoven needle punching, pre-shrinking of the fabric, polyurethane impregnation, alkali reduction, setting and drying, brushing, dyeing, drying, finishing and inspection and packaging.

[0027] The temperature for pre-shrinking the fabric is controlled at 90-150℃; the concentration of the alkali solution for alkali reduction is controlled at 1%-5%, and the temperature is controlled at 80-100℃; the setting temperature for setting and drying is controlled at 90-150℃; and the dyeing temperature is controlled at 100-130℃.

[0028] The beneficial effects of this invention are as follows:

[0029] (1) This application provides a nonwoven fabric made of polyester and pre-oxidized fiber and its preparation method, as well as the application of the nonwoven fabric in carbon fiber preparation; by reasonably selecting the ratio of polyester to pre-oxidized fiber (15%-70% polyester and 30%-85% pre-oxidized fiber) and adopting specific opening, carding, web laying and needle punching processes, the technical problems of easy breakage, uneven distribution and poor entanglement of mixed fibers during processing are successfully solved.

[0030] (2) The polyester and pre-oxidized yarn blended nonwoven fabric obtained in this application has good uniformity, mechanical properties and processability, which can meet the requirements of subsequent carbonization treatment, while significantly reducing the raw material cost. In addition, by optimizing the needle punching process parameters (such as staged needle punching, needle type selection, needle punching density and depth, etc.), the density and structural stability of the nonwoven fabric are further improved;

[0031] (3) At the application level, the hybrid nonwoven fabric can be used for the continuous production of carbon fiber. Compared with ordinary fiber, the carbon fiber produced can absorb odors, improve flame retardant effect, and is lightweight per unit area, which can achieve lightweighting and is suitable for shoe materials, automotive interiors, home textiles, electronic products and other scenarios. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] A polyester-pre-oxidized yarn blended nonwoven fabric, comprising, by weight percentage, 15%-70% polyester and 30%-85% pre-oxidized yarn. Further, by weight percentage, the blended nonwoven fabric comprises 15% polyester and 85% pre-oxidized yarn.

[0034] A method for preparing a nonwoven fabric blended with polyester and pre-oxidized yarn includes the following steps:

[0035] (1) Raw material preparation

[0036] Prepare polyester and pre-oxidized yarn according to the above component ratio and mix them together;

[0037] (2) Opening process

[0038] The above-mentioned mixed raw materials are fed into the opening machine. The speed of the opening machine beater is adjusted to 650-800 rpm. The opening gap of the opening machine is adjusted according to the fiber length, linear density and crimp to make the short fibers open gently.

[0039] (3) Combing process

[0040] After opening, the short fibers are fed into the carding machine. The conventional speed ratio of the carding machine is adjusted to 15-18, the cylinder speed is 650-800 rpm, the distance between the cylinder and the doffer is 0.25-0.35 mm, and the distance between the transfer rollers is 0.1 mm.

[0041] (4) Mesh laying process

[0042] The combed fiber web is fed into the web laying machine. The web laying speed of the web laying machine is controlled below 40m / min, and the stroke of the web laying machine trolley is adjusted to stretch to 100-120%.

[0043] (5) Needle Puncture Technique

[0044] After the fiber web is laid, a multi-stage needle punching process is used to gradually increase the degree of entanglement.

[0045] In step (1), after mixing polyester and pre-oxidized yarn, the humidity in the workshop is controlled at 40%-70%. If the humidity of the production environment is too high: humidity > 70% will cause the fibers to absorb moisture, resulting in opening and sticking, and the breakage rate during opening will exceed 30%, resulting in poor uniformity of the web and easy growth of microorganisms in the finished product; if the humidity of the production environment is too low: humidity < 40% will cause static electricity to accumulate during production, resulting in fiber dispersion, uneven web laying, and large fluctuations in basis weight. In addition, the humidity of the raw material storage environment should be ≤ 50%; the temperature in the production environment should be controlled at 25±5℃; and the humidity should be controlled at 40-60%RH, with priority given to controlling ≤ 50%RH to reduce moisture absorption.

[0046] The specific process of step (2) is as follows: For long fibers with a length of 51 mm or more, a large opening spacing of 8-12 mm is used; for short fibers with a length of less than 38 mm, a small opening spacing of 5-8 mm is used; for coarse denier fibers with a linear density of 3D or more, a large opening spacing of 8-12 mm is used; for fine denier fibers with a linear density of less than 3D, a small opening spacing of 5-8 mm is used; for a crimp count of 15-30, a large opening spacing of 8-12 mm is used; for a crimp count of 30-50, a small opening spacing of 5-8 mm is used. If the spacing is too large, it will lead to insufficient fiber opening, resulting in a web with more impurities and poor uniformity; if the spacing is too small, it will lead to fiber breakage and an increased short fiber rate; if the spacing is uneven, it will lead to excessive opening or clumping of local fibers.

[0047] In step (3), if the cylinder operates at a high speed (>1000 rpm), it will have the following positive effects: enhanced combing effect, high single fiber rate, improved web uniformity, and enhanced fiber orientation (increased longitudinal strength); negative effects: increased fiber damage (short fiber rate >12%), static electricity accumulation, increased fly waste, and increased energy consumption (up to 30%). If the cylinder operates at a low speed (<800 rpm), it will have the following positive effects: reduced fiber breakage (short fiber rate ≤8%), reduced static electricity, and low energy consumption; negative effects: insufficient combing and poor fiber orientation (decreased transverse strength). If the gap between the cylinder and the doffer is <0.2 mm, it will have the following positive effects: high web transfer efficiency (stable basis weight) and enhanced fiber orientation (increased longitudinal strength); negative effects: excessive fiber stretching (increased breakage rate). If the gap between the cylinder and the doffer is >0.3 mm, it will have the following positive effects: reduced fiber damage (decreased short fiber rate); negative effects: insufficient fiber transfer (decreased web bulkiness) and large basis weight fluctuations.

[0048] In step (4), the travel of the web laying machine trolley is adjusted to stretch to 100-110%. High-speed web laying (>100m / min): uneven fiber distribution (longitudinal stripes), increased web basis weight fluctuation; low-speed web laying (<50m / min): fibers tend to accumulate (excessively thick lateral edges). Excessively long trolley travel (over-coverage): excessive fiber dispersion (low basis weight in the middle area), increased equipment load, and higher energy consumption; excessively short trolley travel (insufficient coverage): the web is too thin on both sides and too thick in the middle, with a lateral basis weight gradient >15%.

[0049] The multi-stage acupuncture process in step (5) includes three levels: pre-puncture, main puncture, and fine puncture. The pre-puncture needles are size 36-38, and the acupuncture density is 60-80 needles / m. 2 The needle depth is 6-8mm, the main puncture needle is size 40-42, and the needle density is 150-300 needles / m². 2The needle depth is 3-6mm; the needle used for precision puncture is size 42-45, and the needle density is 400-600 needles / m². 2 The needle depth is 0.5-1mm. The needle angles for pre-needling, main needleling, and fine needleling are all 15°-20°. The influence of needle size: If the needle is too coarse, the piercing force is strong, the risk of fiber damage is high (increased short fiber content), the entanglement effect is tight but the surface is rough; if the needle is too fine, the piercing force is weak, the risk of fiber damage is low (preserving fiber integrity), the entanglement effect is uniform and the surface is smooth. The influence of needle density: If the needle density is too high: the fiber entanglement is too tight, air permeability decreases, fiber damage is aggravated, and the finished product lacks softness; if the needle density is too low: fiber integrity, finished product softness and air permeability are good, but strength is low, structure is loose, and it is easy to delaminate. The influence of needle depth: If the depth is too deep, longitudinal strength and interlayer bonding are good, but fiber breakage rate is high, air permeability is poor, and the finished product surface is rough. If the depth is too shallow, fiber integrity, finished product air permeability are good, and the surface is smooth, but at the same time, entanglement is insufficient and transverse strength is low.

[0050] An application of preparing carbon fiber using a blend of polyester and pre-oxidized yarn nonwoven fabric includes the following steps in sequence: nonwoven needle punching, pre-shrinking of the fabric, polyurethane impregnation, alkali reduction, setting and drying, brushing, dyeing, drying, finishing and inspection and packaging.

[0051] The purpose of pre-shrinking the fabric is to allow the nonwoven fabric to shrink fully, thereby improving its texture, reducing the width from 175cm to 150cm, increasing the density by 25% ± 5, and controlling the temperature at 90-150℃.

[0052] The purpose of polyurethane impregnation is to give the nonwoven fabric a leather-like feel. The pre-shrunken nonwoven fabric is impregnated in liquid polyurethane, with the addition of penetrants and other additives to ensure complete penetration of the entire base fabric. The liquid retention rate is controlled using extrusion rollers to achieve the optimal polyurethane content for the desired texture within the nonwoven fabric. Then, it is cured for the next process.

[0053] The purpose of alkali reduction is to react away 15%-70% of the COPET in polyester, making its fuzzy edges delicate and its hand feel softer. The temperature is controlled at 80-100℃, and the concentration of liquid alkali is controlled at 1%-5% to ensure that there is no COPET residue so as not to affect subsequent dyeing and the final texture.

[0054] The purpose of shaping and drying is to dry the base after reducing the amount of alkali, and at the same time to unify the overall width. The temperature is controlled at 90-150℃ and the time is controlled at 5-10 minutes.

[0055] The purpose of sanding is to comb and smooth out the coarse, long, and messy hairs on the bass surface. The sandpaper used in the sanding process should be 100-600 grit (the higher the grit, the finer the hairs), and the speed of the sanding roller should be controlled at 600-1200 r / min.

[0056] The purpose of dyeing is to dye the brushed base to the desired color using a water bath method at a temperature of 100-130℃. The dyeing process requires careful control of the amount of dye used and the compatibility between different colors of dye to achieve high fastness.

[0057] The purpose of post-treatment: functional treatment (waterproof, antibacterial, antistatic, etc.).

[0058] Specifically, the nonwoven needle punching process ensures uniform density, consistent thickness, and minimal needle punch marks; the pre-shrinking process involves an increased temperature gradient, resulting in uniform and repeated shrinkage of the carbon fiber nonwoven fabric; the resin impregnation environment incorporates an appropriate amount of environmentally friendly flame retardant in the polyurethane resin to guarantee the final material achieves the required flame retardant effect; during alkali reduction, the concentration of liquid alkali is generally controlled below 2% to avoid performance damage to the carbon fiber material; the setting and drying process controls the setting temperature between 90-150℃; the sanding process controls the sanding amount and rotation speed to achieve a certain granular texture and fine finish; and the dyeing process controls the dyeing temperature (generally between 100-130℃) to ensure uniform dyeing without any visible traces of the base material.

[0059] Example 1

[0060] A blended nonwoven fabric was prepared by selecting 15% polyester and 85% pre-oxidized yarn by weight and using the above method.

[0061] Example 2

[0062] The other steps are the same as in Example 1, except that 35% polyester and 65% pre-oxidized yarn are selected by weight percentage.

[0063] Example 3

[0064] The other steps are the same as in Example 1, except that 50% polyester and 50% pre-oxidized yarn are selected by weight percentage.

[0065] Example 4

[0066] The other steps are the same as in Example 1, except that 70% polyester and 30% pre-oxidized yarn are selected by weight percentage.

[0067] Comparative Example 1

[0068] The other steps are the same as in Example 1, except that the raw material used is 100% polyester.

[0069] Comparative Example 2

[0070] The other steps are the same as in Example 1, except that the raw material used is 100% pre-oxidized fiber.

[0071] The nonwoven fabrics prepared in Examples 1-4, Comparative Examples 1 and 2 were tested for basis weight (GB / T 4669-2008), thickness (GB / T 3820), tensile strength (GB / T 1040.3), elongation at break (GB / T 1040.3), tear strength (GB / T 3917.3), pilling properties (GB / T 4802.2-2008), and flammability (GB 8410). The specific results are shown in the table below:

[0072]

[0073] As shown in the table above, Examples 1 to 4 respectively demonstrate the performance of blended nonwoven fabrics containing different proportions of polyester and pre-oxidized yarn in terms of basis weight, thickness, breaking strength, elongation at break, tear strength, flammability, and pilling properties. For example, when the ratio of polyester to pre-oxidized yarn is 15%:85% (Example 1), its basis weight is 334 g / m². 2 The thickness is 3.36 mm, and when the ratio is adjusted to 70%:30% (Experimental Example 4), the basis weight increases to 355.67 g / m³. 2 The thickness is 3.29mm.

[0074] The data on breaking strength and elongation at break show that with the increase of polyester content, the breaking strength of the material in both the warp and weft directions significantly improves. For example, the warp breaking strength of Experiment 4 reaches 651.9 N, far exceeding the 212.77 N of Experiment 1. Simultaneously, the elongation at break shows a similar trend, indicating an increase in the material's toughness. However, in terms of tear strength and flammability, all experimental examples performed excellently, with tear strength exceeding 100 N in all directions and flammability ratings of A-0, demonstrating good fire resistance. As for pilling performance, with the increase of pre-oxidized fiber content, the pilling phenomenon of the fabric gradually improved, resulting in better fabric appearance and hand feel.

[0075] Furthermore, Comparative Examples 1 and 2 demonstrate the performance of 100% polyester and 100% pre-oxidized fiber materials, respectively, as benchmarks for comparison. The results show that while pure polyester material has higher breaking strength and tear strength, its flammability is poor; while pure pre-oxidized fiber material is slightly inferior in all performance aspects.

[0076] In summary, this application provides a polyester / pre-oxidized fiber blended nonwoven fabric and its preparation method, as well as its application in carbon fiber preparation. By rationally selecting the ratio of polyester to pre-oxidized fiber (15%-70% polyester and 30%-85% pre-oxidized fiber) and employing specific opening, carding, web-laying, and needle-punching processes, the technical challenges of easy breakage, uneven distribution, and poor entanglement of blended fibers during processing are successfully solved. Furthermore, the polyester / pre-oxidized fiber blended nonwoven fabric obtained in this application exhibits good uniformity, mechanical properties, and processability, meeting the requirements of subsequent carbonization treatment while significantly reducing raw material costs. In addition, by optimizing needle-punching process parameters (such as staged needle-punching, needle type selection, needle density, and depth), the density and structural stability of the nonwoven fabric are further improved.

[0077] At the application level, the hybrid nonwoven fabric disclosed in this application can be used for the continuous production of carbon fiber. Compared with ordinary fibers, the carbon fiber produced can absorb odors (the test was conducted according to the Q / BYDQ-A1901.404 specification, and the produced carbon fiber was placed in an 80℃ electric constant temperature drying oven and baked for 2 hours, and then rated by human evaluation), improve the flame retardant effect (the combustion characteristics of both the warp and weft directions are A-0), and is lightweight per unit area, which can achieve weight reduction. It is suitable for shoe materials, automotive interiors, home textiles, electronic products and other scenarios.

[0078] It should be noted that all weight coefficients, thresholds, threshold ranges, and target values ​​in this invention are empirical values ​​and can be modified based on the characteristics of the data to be evaluated.

[0079] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for manufacturing a polyester and pre-oxidized yarn mixed nonwoven fabric, characterized by comprising the steps of: It comprises the following steps: ​ (1) Raw material preparation According to the weight percentage, the mixed non-woven fabric comprises the following components: 15%-70% polyester and 30%-85% pre-oxidized yarn, and the polyester and pre-oxidized yarn are prepared according to the above component ratio for mixing; (2) Opening process The mixed raw material is input into the opening machine, the beater speed of the opening machine is adjusted to 650-800 rpm, and the opening distance of the opening machine is adjusted according to the fiber length, linear density and crimp degree, so that the short fibers are gently opened; (3) Carding process The opened short fibers are input into the carding machine, the conventional speed ratio of the carding machine is adjusted to 15-18, the speed of the cylinder is 650-800 rpm, the distance between the cylinder and the doffer is 0.25-0.35 mm, and the distance between the transfer roller is 0.1 mm; (4) Laying process The fiber web after carding is input into the laying machine, the laying speed of the laying machine is controlled below 40 m / min, and the laying machine trolley stroke adjustment is stretched to 100-120%; (5) Needle punching process The fiber web after laying is further subjected to multi-stage needle punching process to gradually improve the entanglement degree; The specific process of step (2) is as follows: long fibers with a fiber length of more than 51 mm use a large opening distance of 8-12 mm; short fibers with a fiber length of less than 38 mm use a small opening distance of 5-8 mm; thick fibers with a linear density of more than 3D use a large opening distance of 8-12 mm; thin fibers with a linear density of less than 3D use a small opening distance of 5-8 mm; fibers with a crimp number of 15-30 use a large opening distance of 8-12 mm, and fibers with a crimp number of 30-50 use a small opening distance of 5-8 mm; The multi-stage needle punching process in step (5) includes pre-punching, main punching and fine punching, the pre-punching needle has a size of 36-38, the needle punching density is 60-80 needles / m², and the needle depth is 6-8 mm; the main punching needle has a size of 40-42, the needle punching density is 150-300 needles / m², and the needle depth is 3-6 mm; the fine punching needle has a size of 42-45, the needle punching density is 400-600 needles / m², and the needle depth is 0.5-1 mm.

2. The method for preparing a nonwoven fabric blended with polyester and pre-oxidized yarn as described in claim 1, characterized in that, According to the weight percentage, the mixed non-woven fabric comprises the following components: 15% polyester and 85% pre-oxidized yarn.

3. The method for preparing a nonwoven fabric blended with polyester and pre-oxidized yarn as described in claim 1, characterized in that: In step (1), the humidity in the workshop is controlled at 40%-70% after mixing the polyester and pre-oxidized yarn.

4. The method for preparing a nonwoven fabric blended with polyester and pre-oxidized yarn as described in claim 1, characterized in that: In step (4), the laying machine trolley stroke adjustment is stretched to 100-110%.

5. The method for preparing a nonwoven fabric blended with polyester and pre-oxidized yarn as described in claim 1, characterized in that: The needle leaf angle of the pre-punching, main punching and fine punching is 15°-20°.

6. Use of the nonwoven fabric obtained using the production method according to claim 1 for the production of carbon fibers, characterized in that, It comprises the following steps in sequence: non-woven needle punching, gray cloth pre-shrinking, polyurethane impregnation, alkali reduction, setting drying, sanding, dyeing, drying, finishing and inspection packaging.

7. Use according to claim 6, wherein: The temperature of the gray cloth pre-shrinking is controlled at 90-150℃; the concentration of the liquid alkali for the alkali reduction is controlled at 1%-5%, and the temperature is controlled at 80-100℃; the setting temperature of the setting drying is controlled at 90-150℃; the dyeing temperature is controlled at 100-130℃.

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