阅读说明：本技术 一种提高纤维素纤维强度的方法及其制备的纤维素纤维 (Method for improving strength of cellulose fiber and cellulose fiber prepared by method ) 是由 李昌垒 刘长军 马君志 颜晶 秦翠梅 刘乐 王东 吴亚红 于 2020-05-26 设计创作，主要内容包括：本发明提供一种提高纤维素纤维强度的方法,所述方法包括制备纺丝原液；所述制备纺丝原液,将改性聚酰胺环氧氯丙烷树脂和羧甲基纤维素(CMC)与粘胶原液共混；通过利用三聚氰胺或者苯代三聚氰胺对聚酰胺环氧氯丙烷进行改性,增加了分子链间的距离,降低了制备的高强度纤维素纤维的刚性,使得其断裂伸长率与常规纤维素纤维差别不大；通过在纺丝成型及后处理工序中添加改性聚酰胺环氧氯丙烷树脂和高取代度的CMC,避免了在纺丝成型和后处理过程中改性物质流失造成的影响,确保了后续在纤维中的交联效果；制备的纤维干断裂强度2.77~3.05cN/dtex,湿断裂强度1.69~1.95c/dtex。(The invention provides a method for improving the strength of cellulose fiber, which comprises the steps of preparing a spinning solution; preparing a spinning stock solution, namely blending modified polyamide epichlorohydrin resin and carboxymethyl cellulose (CMC) with a viscose stock solution; the polyamide epichlorohydrin is modified by using the melamine or the benzoguanamine, so that the distance between molecular chains is increased, the rigidity of the prepared high-strength cellulose fiber is reduced, and the breaking elongation of the high-strength cellulose fiber is not much different from that of the conventional cellulose fiber; by adding the modified polyamide epichlorohydrin resin and the CMC with high substitution degree in the spinning forming and post-treatment processes, the influence caused by loss of modified substances in the spinning forming and post-treatment processes is avoided, and the subsequent crosslinking effect in the fiber is ensured; the prepared fiber has dry breaking strength of 2.77-3.05 cN/dtex and wet breaking strength of 1.69-1.95 c/dtex.)

1. A method of increasing the strength of cellulosic fibers, characterized by: the method comprises preparing a spinning dope; the preparation of the spinning stock solution comprises the step of blending the modified polyamide epichlorohydrin resin, the CMC and the viscose stock solution.

2. A method of increasing the strength of cellulosic fibers according to claim 1, wherein: the mass ratio of the modified polyamide epichlorohydrin resin, the CMC and the alpha cellulose in the viscose stock solution is 3.5-7.0:1.0-2.5: 90.5-95.5.

3. A method of increasing the strength of cellulosic fibers according to claim 1, wherein: the method also comprises spinning and forming; and spinning and forming, wherein the coagulating bath comprises 0.5-1.5% of modified polyamide epichlorohydrin resin, and the second bath comprises 1.0-3.0% of modified polyamide epichlorohydrin resin.

4. A method of increasing the strength of cellulosic fibers according to claim 1, wherein: the method also comprises post-treatment, wherein the post-treatment comprises 0.5-1.0% of modified polyamide epichlorohydrin resin and 0.5-1.0% of CMC in an oil bath.

5. A method of increasing the strength of cellulosic fibers according to any of claims 1, 2 or 4, wherein: the degree of substitution of the CMC is 1.0 to 1.5.

6. A method of increasing the strength of cellulosic fibres, as claimed in any one of claims 1 to 4, in which: the modification method of the modified polyamide epichlorohydrin resin comprises the steps of adjusting the solid content of a polyamide prepolymer in a polyamide prepolymer solution to be 30% -50%, cooling to 90-120 ℃, adding melamine or benzoguanamine, wherein the amount of the melamine or benzoguanamine is 10% -30% of that of the polyamide prepolymer, reacting for 30-90min, cooling the product to 50-80 ℃, adding epichlorohydrin under the condition that the pH value is 7.5-9.5, the amount of the epichlorohydrin is 30% -50% of that of the polyamide prepolymer, reacting for 2.0-4.0 hours, adjusting the pH value to be 2.0-5.0, stopping the reaction, adjusting the pH value to be neutral, and enabling the solid content to be 10% -15%, thus obtaining the modified polyamide epichlorohydrin resin solution.

7. A method of increasing the strength of cellulosic fibers according to claim 1, wherein: the viscose stock solution comprises 8.2-9.0% of alpha cellulose, 4.5-5.1% of sodium hydroxide, 45-55 s of viscosity and 10% of NH₄The aging degree under Cl is 16-22 mL.

8. A method of increasing the strength of cellulosic fibers according to claim 3, wherein: the coagulating bath also comprises 7.5-8.5% of sulfuric acid, 1.2-1.6% of zinc sulfate and 22.5-26.0% of sodium sulfate; the two baths also comprise 10-20 g/L sulfuric acid.

9. A method of increasing the strength of cellulosic fibers according to claim 4, wherein:

in the post-treatment, sodium hydroxide is adopted in a desulfurization bath, and the concentration is 4.0-8.0 g/L; the upper oil bath also comprises 3.0-6.0 g/L of oil solution; the method further comprises drying, wherein the drying temperature is 125-140 ℃, and the drying time is 30-90 min.

10. The cellulosic fiber produced by the method of increasing the strength of cellulosic fiber of claim 1, wherein: the fiber contains 3.25 to 6.67 percent of modified polyamide epichlorohydrin resin and 0.89 to 2.26 percent of CMC; the dry breaking strength is 2.77-3.05 cN/dtex, the fiber shrinkage is 1.1-1.6%, and the fuzzing and pilling grade of the made fabric is 4-5.

Technical Field

The invention relates to a method for improving the strength of cellulose fibers and cellulose fibers prepared by the method, in particular to a method for preparing high-strength cellulose fibers by using cellulose pulp, wet strength agent modified polyamide epichlorohydrin resin (PAE resin) and sodium carboxymethylcellulose (CMC) as main raw materials and fibers thereof, belonging to the technical field of textile.

Background

Due to good hygroscopicity, comfortable wearing and excellent spinnability, the cellulose fiber has wide application, is often blended and interwoven with cotton, wool or various synthetic fibers, and is used for various clothes and decorative textiles. However, the common cellulose fiber has relatively low strength, is swollen by water in a wet state, has obvious strength reduction, poor dimensional stability and abrasion resistance and influences the wearability of the fabric. Therefore, the method for improving the performance of the cellulose fiber by process modification and other methods is an important direction for the development of the cellulose fiber, and a new variety of the cellulose fiber with high strength, high modulus, good size stability and excellent wear resistance is prepared.

Chinese patent CN201811436865.7 discloses a preparation method of high-orientation high-toughness regenerated cellulose fiber and the high-orientation high-toughness regenerated cellulose fiber. The patent technology firstly mixes regenerated cellulose solution with cross-linking agent to obtain mixed solution of regenerated cellulose and cross-linking agent; the cross-linking agent is selected from epoxy compound and/or aldehyde compound, including epichlorohydrin and epoxy chlorobutane or glutaraldehyde and succinaldehyde. The aldehyde substance is used, which easily causes environmental pollution, worsens the working environment and limits the production.

The polyamide epichlorohydrin resin (PAE) is the most common wet strength agent in the papermaking field, and has the characteristics of high efficiency, wide application range and the like. In addition to increasing the wet strength properties of paper, PAE can also increase the dry strength to various degrees. Sodium carboxymethylcellulose (CMC) is a water-soluble cellulose derivative which is used more at present, is often used as a water retention agent in coating, and can also be used for improving the dry strength of paper. The contents of the above-mentioned systems are disclosed in the published papers "PAE/CMC two-dimensional enhancement system research" (Li Jian et al), "CS/CMC two-dimensional enhancement system preparation and application" (Cao Xiao Yao et al), "CMC/CTAB two-dimensional paper enhancement system action and mechanism research" (Chenlin et al), "PAE/CMC two-dimensional enhancement system application research in old corrugated paper pulp" (Pailajuan et al), patent CN201210445338.9 (a paper-making enhancement method), CN201510668362.2 (a production method of medical packaging paper with high antibacterial property), and so on.

By analysis, the application is limited to papermaking and has not been studied in other aspects. Because of the great difference between papermaking and fiber forming, the main points are as follows:

1. different characteristics of the final product

The fiber obtained by papermaking is a two-dimensional sheet structure substance, while the cellulose fiber is a substance with a thin and long structure with a certain length-diameter ratio, which determines the difference of the cellulose fiber and the cellulose fiber in the forming process, so that the cellulose fiber is more refined in the forming process, and the auxiliary agent has higher requirements in the application process.

2. Different technological process and technological conditions

The main flow in the papermaking process comprises the working procedures of cooking, washing, bleaching and the like, and most of the working procedures are carried out under the alkaline condition; the process flow of the cellulose fiber comprises the working procedures of dipping, squeezing, crushing, sulfonating, dissolving, spinning and the like, wherein the former phase is mainly carried out under alkaline conditions, and the spinning is carried out in acid bath acidity, so that the prior polyamide epichlorohydrin resin and CMC can be greatly different when used for papermaking and the cellulose fiber.

In the early stage test, the applicant finds that the polyamide epichlorohydrin resin can increase the rigidity of the fiber and reduce the elongation at break while improving the strength of the cellulose in the preparation process of the cellulose fiber; the polyamide epichlorohydrin resin and the CMC are easy to run off in the spinning forming and post-treatment processes, so that the crosslinking effect of the polyamide epichlorohydrin resin and the CMC in fibers is poor, and the strength of cellulose fibers is difficult to improve.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method for improving the strength of cellulose fibers, which takes cellulose pulp, modified polyamide epichlorohydrin resin and high-substitution-degree CMC as raw materials, and improves the processes of shaping such as preliminary and simultaneous preforming of three components in a coagulating bath, further shaping in a second bath, oil bath treatment and the like by adjusting the composition of the coagulating bath and the post-treatment process, so that the retention amount of the modified polyamide epichlorohydrin resin is increased, high-temperature curing is performed in the drying process, and the bonding effect of the CMC is combined to further play a role in enhancing, so that the high-strength cellulose fibers are obtained, and the following technical problems are solved:

(1) the crosslinking and bonding effects of the modified polyamide epichlorohydrin resin and the CMC in the fiber are ensured, and the strength of the cellulose fiber is improved;

(2) the strength of the fiber is improved, the density of cross-linking points in the fiber is reduced, the rigidity of the fiber is reduced, and the influence on the elongation at break is small.

Another technical problem to be solved by the present invention is to provide a high-strength cellulose fiber prepared by the method.

In order to solve the technical problems, the invention adopts the following technical scheme:

a method of increasing the strength of cellulosic fibers, the method comprising preparing a dope; the preparation of the spinning stock solution comprises the step of blending the modified polyamide epichlorohydrin resin, the CMC and the viscose stock solution.

The following is a further improvement of the above technical solution:

the preparation method comprises the following steps:

(1) cellulose pulp is used as raw material and is soaked, squeezed, crushed, aged and yellowThe step of dissolving and dissolving is carried out to prepare a viscose stock solution, wherein the alpha cellulose accounts for 8.2-9.0%, the sodium hydroxide accounts for 4.5-5.1%, the viscosity accounts for 45-55 s, and the ripening degree is 16-22 mL (10% NH)₄Cl）；

(2) Adding the prepared modified polyamide epichlorohydrin resin and CMC into a viscose stock solution, blending, and fully mixing to obtain a spinning stock solution, or adding the modified polyamide epichlorohydrin resin and CMC into the viscose stock solution according to a proportion by using a pre-spinning injection device to obtain the spinning stock solution;

preferably, the ratio of the modified polyamide epichlorohydrin resin, the CMC and the alpha cellulose in the viscose stoste in the step (2) is 3.5-7.0:1.0-2.5: 90.5-95.5.

Preferably, the preparation and modification method of the modified polyamide epichlorohydrin resin in the step (2) comprises the following steps: preparing an intermediate polyamide prepolymer solution according to known knowledge, adjusting the solid content of the polyamide prepolymer to be 30-50%, cooling to 90-120 ℃, adding melamine or benzoguanamine, wherein the amount of melamine or benzoguanamine is 10-30% of that of the polyamide prepolymer, reacting for 30-90min, cooling the product to 50-80 ℃, and adjusting the pH value to 2.0-5.0 after reacting for 2.0-4.0 h under the condition that the pH value is 7.5-9.5 (the pH value of the system is ensured in the reaction process), adding epichlorohydrin into the system, wherein the amount of epichlorohydrin is 30-50% of that of the polyamide prepolymer, stopping the reaction to obtain a modified polyamide epichlorohydrin resin solution, adjusting the pH value of the modified polyamide epichlorohydrin resin solution to be neutral, and enabling the solid content of the modified polyamide epichlorohydrin resin solution to be 10-15%.

Preferably, the carboxymethyl cellulose (CMC) in the step (2) has a substitution degree of 1.0 to 1.5, and is added to the modified polyamide-epichlorohydrin resin solution prepared above during use.

(3) And (3) filtering, defoaming, spinning and forming and post-treating the spinning solution after post-dissolving and blending, or spinning and forming, post-treating and drying the spinning solution obtained by blending through a pre-spinning injection device to obtain the high-strength cellulose fibers.

Preferably, in the spinning forming process in the step (3), the coagulation bath composition is adjusted, and the coagulation bath composition contains 0.5-1.5% of modified polyamide epichlorohydrin resin in addition to 7.5-8.5% of sulfuric acid, 1.2-1.6% of zinc sulfate, and 22.5-26.0% of sodium sulfate.

Preferably, in the spinning forming process in the step (3), the two-bath composition is adjusted, and the modified polyamide epichlorohydrin resin contains 10-20 g/L of sulfuric acid and 1.0-3.0%.

Preferably, in the post-treatment process in the step (3), sodium hydroxide is adopted in a desulfurization bath with the concentration of 4.0-8.0 g/L except for the conventional viscose fiber post-treatment process, and the desulfurization bath not only achieves the purpose of removing sulfur elements in the fibers, but also can provide a proper pH value for the modified polyamide epichlorohydrin resin to promote the crosslinking and curing of the modified polyamide epichlorohydrin resin.

Preferably, in the post-treatment process in the step (3), the composition of the oil bath is adjusted, and the oil bath contains 3.0-6.0 g/L of oil agent, 0.5-1.0% of modified polyamide epichlorohydrin resin and 0.5-1.0% of CMC.

Preferably, in the drying step in the step (3), the drying temperature is 125-140 ℃, the drying time is 30-90min, and the wet strength agent is ensured to be crosslinked.

In the production process, the preparation process, the spinning process and the post-treatment process of the viscose dope can be properly adjusted according to the production requirement and the requirement on the product.

The main components of the fiber prepared by the invention comprise 3.25-6.67% of modified polyamide epichlorohydrin resin and 0.89-2.26% of carboxymethyl cellulose (CMC). The polyamide epichlorohydrin resin can form an interpenetrating copolymer network structure in a cellulose fiber matrix, so that the polyamide epichlorohydrin resin has a remarkable enhancing effect, the melamine or benzoguanamine is used for modifying the cellulose fiber matrix to further improve the performance of the cellulose fiber matrix, and the bonding effect of CMC is combined, so that the dry breaking strength of the fiber is 2.77-3.05 cN/dtex, the wet breaking strength is 1.69-1.95 c/dtex, the wet modulus is 0.40-0.65 cN/dtex, and the elongation at break is 15.1-18.3%.

The invention adopts the technical scheme with the beneficial effects that:

1. the polyamide epichlorohydrin is modified by using melamine or benzoguanamine, so that the distance between molecular chains is increased, the rigidity of the prepared high-strength cellulose fiber is reduced, and the breaking elongation of the high-strength cellulose fiber is not much different from that of the conventional cellulose fiber.

2. By adding the modified polyamide epichlorohydrin resin and the CMC with high substitution degree in the spinning forming and post-treatment processes, the influence caused by loss of modified substances in the spinning forming and post-treatment processes is avoided, and the subsequent crosslinking effect in the fiber is ensured.

3. The high-strength cellulose fiber not only has a series of advantages of the cellulose fiber, but also has the added modified polyamide epichlorohydrin resin, CMC and cellulose matrix existing in the form of interpenetrating copolymer network, and the modified substance is used as an organic matter, so that the compatibility with the polymer matrix can be improved, and the phenomenon of phase separation is avoided. Therefore, the wet strength and modulus of the fiber are remarkably improved compared with those of common cellulose fibers, the dry breaking strength of the prepared fiber is 2.77-3.05 cN/dtex, the wet breaking strength is 1.69-1.95 cN/dtex, the wet modulus is 0.40-0.65 cN/dtex, the elongation at break is 15.1-18.3%, the fiber shrinkage is 1.1-1.6%, and the fuzzing and pilling grade of the prepared fabric is 4-5, so that the fiber has good mechanical properties and textile processability.

4. The preparation method provided by the invention has a simple process, can be completed on the basis of the existing cellulose fiber production process and equipment, and the strength and modulus of the prepared fiber are greatly improved compared with those of common cellulose fibers, so that a new thought and method are provided for the functional development of regenerated cellulose fibers, and the preparation method has a good development prospect.

The present invention will be described in detail with reference to examples.

Detailed Description

The following description of the preferred embodiments of the present invention is provided for the purpose of illustration and description, and is in no way intended to limit the invention.