Polylactic acid tow for cigarette filter as well as preparation method and application of polylactic acid tow

Abstract

The invention discloses a polylactic acid tow for a cigarette filter as well as a preparation method and application of the polylactic acid tow. The polylactic acid tow comprises the following raw materials: polylactic acid, a cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate and an antioxidant. The cellulose diacetate grafted hyperbranched polymer is prepared from cellulose diacetate and an amino-terminated hyperbranched polymer through a reaction. According to the invention, the cellulose diacetate grafted hyperbranched polymer and the polypropylene carbonate are added into the polylactic acid, and the introduction of the cellulose acetate can solve the problem of adhesion of the filter stick; the grafting of the hyperbranched polymer can improve the interfacial compatibility of the cellulose acetate and the polylactic acid, increase the plasticization of the cellulose diacetate and widen the processing window temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a polylactic acid tow for cigarette filter, and a preparation method and application thereof. BACKGROUND

[0002] An excellent cigarette filter can have a good adsorption and retention effect on harmful components in cigarette smoke, while retaining the flavor of tobacco. For the raw material of cigarette filter, acetate fiber tow and polypropylene tow are the most common cigarette filter raw materials in the domestic market. Acetate fiber filter is a mechanical filter widely accepted by low tar and high tar cigarette consumers today. It is non-toxic, odorless, impact-resistant, oil-resistant, non-static, has small suction resistance, strong adsorption, and has good elasticity and thermal stability. However, the price of acetate fiber is high, which is 3-8 times that of ordinary fiber, which limits its application range. Polypropylene fiber is inexpensive, but polypropylene filter rod needs to be formed and dried by special water-based adhesive, and its inertness makes the filter resistance unstable, which greatly affects the filtering effect and aroma of cigarettes, and cannot be applied to high-end market, hindering its further development.

[0003] Polylactic acid is derived from natural plants, is inexpensive and easy to obtain, can be naturally degraded by the human body, and can be completely degraded into carbon dioxide and water in the environment in a few months, without potential harm to the environment. Polylactic acid is manufactured into tow by melt spinning process, which has low processing cost and almost no environmental pollution. In particular, polylactic acid fiber tow has strong adsorption and elimination force on harmful components in smoke. Therefore, polylactic acid fiber tow is the most promising new environment-friendly cigarette filter material, which has been widely studied. For example, a pure polylactic acid tow and a preparation method and a cigarette filter disclosed in patent CN103088458A are prepared by mixing L-polylactic acid and D-polylactic acid (dextro-polylactic acid), wherein the content of L-polylactic acid is 90% to 98% of the total weight, and the content of D-polylactic acid is 2% to 8%.

[0004] However, polylactic acid tow has the following problems in actual production and use: 1) poor heat resistance of the tow; 2) poor adhesion and hardness of the filter rod. Low-crystalline PLA tow will cause the cutting knife to be unable to cut due to the gradual heating of the cutting knife during cutting. The filter rod is prone to shrinkage during storage and transportation, resulting in unstable appearance and quality of the product. High-crystalline PLA tow does not have the problems of difficult cutting and heat shrinkage, but the plasticizer glyceryl triacetate cannot penetrate, and the adhesion between the tows is poor. SUMMARY

[0005] The present application is to overcome the above-mentioned problems of the prior art polylactic acid tow, and provides a polylactic acid tow for a cigarette filter, a preparation method and application thereof, wherein diacetate cellulose grafted hyperbranched polymer and polypropylene carbonate are added in polylactic acid, the introduction of acetate cellulose can solve the problem of filter stick bonding, the grafting of hyperbranched polymer can improve the interfacial compatibility of acetate cellulose and polylactic acid, increase the plasticity of diacetate cellulose, and expand the processing window temperature.

[0006] In order to achieve the above-mentioned purposes, the present application adopts the following technical solutions: In a first aspect, the present application provides a polylactic acid tow for a cigarette filter, raw materials including polylactic acid, diacetate cellulose grafted hyperbranched polymer, polypropylene carbonate, and antioxidant. The diacetate cellulose grafted hyperbranched polymer is prepared by reaction of diacetate cellulose and amino-terminated hyperbranched polymer.

[0007] Triglyceride triacetate is a safe, non-toxic plasticizer, which is widely used in the production of cigarette filter rods. However, polylactic acid (PLA) lacks strong polar groups, and its molecular structure and solubility parameter are seriously mismatched with triglyceride triacetate, so that triglyceride triacetate cannot dissolve the surface of PLA nor build a network of intermolecular forces, thus resulting in poor adhesion of PLA filaments in the production of cigarette filter rods. The present application adds cellulose diacetate grafted hyperbranched polymer to polylactic acid. The molecular chain of cellulose acetate (CA) is rich in hydroxyl and acetyl groups, forming strong intermolecular hydrogen bonds and entanglement network, resulting in fluffy and difficult to shape fibers. As a solvent type plasticizer, triglyceride triacetate has good compatibility with the polar groups in the cellulose molecule. When triglyceride triacetate is sprayed on the surface of the fiber, it can penetrate into the interstitial space of the fiber, partially dissolve the surface layer of the fiber, and enhance the movement ability of the molecular chain segments, so that the fiber surface is softened and sticky. With the penetration of triglyceride triacetate in the fiber, the dissolved cellulose molecular chains in the fiber are reinterwoven at the fiber contact points, and a new hydrogen bond network is formed between the carbonyl groups in the triglyceride triacetate molecules and the hydroxyl groups in the cellulose. This process locally fuses adjacent fibers at the contact points, and after the solvent is volatilized, the molecular chains are re-solidified, and the fibers form a stable three-dimensional network structure, giving the filter rod the required hardness and shape stability. Therefore, by taking advantage of the compatibility of cellulose acetate and triglyceride triacetate, CA is introduced into PLA, which can solve the problem of filter rod adhesion. However, due to the high melting point of CA and the decomposition temperature before the melting point, and the agglomeration of CA caused by the remaining hydroxyl groups in triglyceride triacetate, the CA is not uniformly dispersed, resulting in unstable melt and easy degradation when CA is directly blended with PLA. Therefore, the present application grafts CA with hyperbranched polymer, which can improve the interfacial compatibility of CA and PLA, increase the plasticity of CA, and expand the processing window temperature. Meanwhile, the present application also adds polypropylene carbonate (PPC), a small amount of which can be dissolved in triglyceride triacetate. In the filter rod forming process, the PPC exposed on the surface adheres to the PPC on the surface of the adjacent filament under the action of triglyceride triacetate, so as to make the filter rod adhere, and further improve the adhesion of polylactic acid filaments.

[0008] Preferably, the mass ratio of cellulose diacetate and amino-terminated hyperbranched polymer is 1:0.05-0.2.

[0009] Preferably, the mass ratio of polylactic acid, cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate and antioxidant is 65-90:5-20:5-15:0.5.

[0010] As preferred, the antioxidant is two or more of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid n-octadecyl ester, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, n-octadecyl propionate, tetra[beta-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester, and tris(2,4-di-tert-butylphenyl) phosphite.

[0011] In a second aspect, the present application provides a preparation method of the above-mentioned polylactic acid tow for cigarette filters, comprising the following steps: (1) preparing cellulose diacetate grafted hyperbranched polymer; (2) preparing modified polylactic acid particles: mixing polylactic acid, cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate and antioxidant and melt extruding to obtain modified polylactic acid particles; (3) preparing polylactic acid tow: spinning the modified polylactic acid particles into Y-shaped tow through a spinning machine, and then performing drawing, crimping and heat setting processes to obtain polylactic acid tow.

[0012] As preferred, the preparation method of the cellulose diacetate grafted hyperbranched polymer in step (1) is as follows: dissolving cellulose diacetate and amino-terminated hyperbranched polymer in an organic solvent, heating the system to 40-80℃, reacting for 5-7h under nitrogen protection, and removing the solvent by vacuum drying to obtain the cellulose diacetate grafted hyperbranched polymer.

[0013] As preferred, the temperature during spinning in step (3) is 220-250℃.

[0014] As preferred, the temperature during drawing in step (3) is 80-100℃, and the drawing ratio is 5-7 times.

[0015] In a third aspect, the present application provides a use of the above-mentioned polylactic acid tow in preparing polylactic acid cigarette filter rods.

[0016] As preferred, the preparation method of the polylactic acid cigarette filter rod is as follows: opening and spreading the polylactic acid tow, spraying the plasticizer glyceryl triacetate on the polylactic acid tow in the form of mist through a filter rod forming machine glue tank, and then wrapping and forming the tow, cutting, to obtain the polylactic acid cigarette filter rod.

[0017] Therefore, the present application has the following beneficial effects: (1) The addition of cellulose diacetate grafted hyperbranched polymer to polylactic acid can expand the processing window temperature of cellulose acetate, improve the dispersion effect of cellulose acetate in PLA, increase the compatibility and toughness of cellulose acetate and PLA, and facilitate subsequent melt spinning; and the polylactic acid fiber can have adhesion without changing the plasticizer glyceryl triacetate; (2) The polylactic acid tow of the present application can be solidified with glyceryl triacetate, and the prepared cigarette filter has high hardness, excellent tensile property, air permeability, filtration efficiency and smoke cooling effect. DETAILED DESCRIPTION

[0018] The present application is further described below in conjunction with specific embodiments.

[0019] In the present application, all the equipment and raw materials can be purchased from the market or commonly used in the industry, and the methods in the following examples are conventional methods in the art unless otherwise specified.

[0020] General examples: A preparation method of a polylactic acid cigarette filter rod comprises the following steps: (1) preparing cellulose diacetate grafted hyperbranched polymer; (2) preparing modified polylactic acid particles: mixing polylactic acid, cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate and antioxidant and melt extruding to obtain modified polylactic acid particles; (3) preparing polylactic acid tow: spinning the modified polylactic acid particles into Y-shaped tow through a spinning machine, and performing drawing, crimping and heat setting processes to prepare polylactic acid tow; (4) opening and spreading the polylactic acid tow, spraying plasticizer glyceryl triacetate in the form of atomization on the polylactic acid tow through a filter rod forming machine glue tank, and then wrapping and forming the tow, cutting to obtain the polylactic acid cigarette filter rod.

[0021] As a specific embodiment, the preparation method of the cellulose diacetate grafted hyperbranched polymer in step (1) is as follows: dissolving cellulose diacetate and amino-terminated hyperbranched polymer in an organic solvent, heating the system to 50-70℃, reacting for 5-7h under nitrogen protection, and removing the solvent by vacuum drying to obtain the cellulose diacetate grafted hyperbranched polymer; preferably, the organic solvent is dichloromethane.

[0022] As a specific embodiment, the preparation method of the amino-terminated hyperbranched polymer is as follows: using diethylenetriamine and methyl acrylate as raw materials, preparing AB2 and AB3 type mixed monomers through the reaction between the two, and then preparing the amino-terminated hyperbranched polymer through the polycondensation reaction between the monomers.

[0023] As a specific embodiment, the mass ratio of the cellulose diacetate and the amino-terminated hyperbranched polymer is 1:0.05-0.2; preferably, the mass ratio of the cellulose diacetate and the amino-terminated hyperbranched polymer is 1:0.1.

[0024] In one specific implementation, the mass ratio of polylactic acid, cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate, and antioxidant in step (2) is 65-90:5-20:5-15:0.5.

[0025] In one specific embodiment, the antioxidant is two or more of the following: β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite, β-octadecyl propionate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and tris(2,4-di-tert-butylphenyl)phosphite.

[0026] In one specific implementation, the spinning temperature in step (3) is 220℃~250℃.

[0027] In one specific implementation, the temperature during stretching in step (3) is 80-100°C, and the stretching ratio is 5-7 times.

[0028] In one specific implementation, the heat setting temperature in step (3) is 90 to 120°C.

[0029] In one specific implementation, the amount of triacetin sprayed in step (4) is 6 to 8% of the mass of polylactic acid filament bundle.

[0030] Example 1: A method for preparing a polylactic acid cigarette filter rod includes the following steps: (1) Preparation of terminal amino hyperbranched polymer: 52 mL of diethylenetriamine was added to a flask and the flask was placed in an ice-water bath. Methyl acrylate-methanol solution (43 mL of methyl acrylate-methanol solution dissolved in 100 mL of methanol) was added dropwise. After the addition was completed, the reaction was carried out for 30 h. The methanol in the system was removed by vacuum. Then the system was transferred to an oil bath and heated to 120 °C in N2 environment for 5 h. The product was thoroughly washed with tetrahydrofuran and finally dried under vacuum to obtain a yellow viscous terminal amino hyperbranched polymer. (2) Preparation of cellulose diacetate grafted hyperbranched polymer: At room temperature, 100g of cellulose diacetate, 5g of terminal amino hyperbranched polymer and 200mL of dichloromethane solvent were added to a flask, the system was heated to 60℃, and reacted for 6h under nitrogen protection. The solvent was removed by vacuum drying to obtain the cellulose diacetate grafted hyperbranched polymer. (3) Preparation of modified polylactic acid particles: Polylactic acid (weight average molecular weight 150,000), cellulose diacetate grafted with hyperbranched polymer, and polypropylene carbonate (Mw = 9.84 × 10⁻⁶) were mixed. 4) and antioxidant in a mass ratio of 75:15:10:0.5 to obtain a premix, and the premix is melt-extruded through a double-screw extruder to obtain modified polylactic acid particles; the antioxidant is pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 2:3; (4) Preparation of polylactic acid filament: the modified polylactic acid particles are spun into Y-shaped filaments through a spinning machine, and are subjected to a drawing, crimping and heat setting process to prepare polylactic acid filaments; the temperature of the spinning box is 230°C, the drawing temperature is 90°C, and the drawing ratio is 6 times; (5) The polylactic acid filaments are opened and spread, and then pass through the glue box of a filter rod forming machine, and the plasticizer glyceryl triacetate is sprayed on the polylactic acid filaments in the form of atomization, with a spraying amount of 6% of the mass of the polylactic acid filaments; then the filaments are wrapped and formed, cut and obtained into the polylactic acid cigarette filter rod.

[0031] Example 2: A method for preparing a polylactic acid cigarette filter rod, comprising the following steps: (1) Preparation of amino-terminated hyperbranched polymer: the method is the same as in Example 1; (2) Preparation of cellulose diacetate grafted hyperbranched polymer: 100 g of cellulose diacetate, 10 g of amino-terminated hyperbranched polymer and 200 mL of dichloromethane solvent are added into a flask at room temperature, the system is heated to 60°C, and the reaction is carried out under nitrogen protection for 6 h; the solvent is removed by vacuum drying to obtain the cellulose diacetate grafted hyperbranched polymer; (3) Preparation of modified polylactic acid particles: polylactic acid (weight average molecular weight 150000), cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate (Mw=9.84x10 4 ) and antioxidant in a mass ratio of 75:15:10:0.5 to obtain a premix, and the premix is melt-extruded through a double-screw extruder to obtain modified polylactic acid particles; the antioxidant is pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 2:3; (4) Preparation of polylactic acid filament: the modified polylactic acid particles are spun into Y-shaped filaments through a spinning machine, and are subjected to a drawing, crimping and heat setting process to prepare polylactic acid filaments; the temperature of the spinning box is 230°C, the drawing temperature is 90°C, and the drawing ratio is 6 times; (5) The polylactic acid filaments are opened and spread, and then pass through the glue box of a filter rod forming machine, and the plasticizer glyceryl triacetate is sprayed on the polylactic acid filaments in the form of atomization, with a spraying amount of 6% of the mass of the polylactic acid filaments; then the filaments are wrapped and formed, cut and obtained into the polylactic acid cigarette filter rod.

[0032] Example 3: A preparation method of a polylactic acid cigarette filter rod, comprising the following steps: (1) preparing an amino-terminated hyperbranched polymer: the method is the same as that in Example 1; (2) preparing a cellulose diacetate grafted hyperbranched polymer: at room temperature, 100 g of cellulose diacetate, 10 g of the amino-terminated hyperbranched polymer and 200 mL of dichloromethane solvent are added into a flask, the system is heated to 60°C, and the reaction is carried out under nitrogen protection for 6 h; vacuum drying is performed to remove the solvent, and the cellulose diacetate grafted hyperbranched polymer is obtained; (3) preparing modified polylactic acid particles: polylactic acid (weight average molecular weight 150000), cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate (Mw=9.84 x 10 4 ) and an antioxidant are uniformly mixed in a mass ratio of 80:10:10:0.5 to obtain a premix, and the premix is melt-extruded through a double-screw extruder to obtain the modified polylactic acid particles; the antioxidant is tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester and tris(2,4-di-tert-butylphenyl)phosphite in a mass ratio of 2:3; (4) preparing polylactic acid filaments: the modified polylactic acid particles are spun into Y-shaped filaments through a spinning machine, and are subjected to a drawing, crimping and heat setting process to prepare the polylactic acid filaments; the temperature of the spinning box is 230°C, the drawing temperature is 90°C, and the drawing ratio is 6 times; (5) the polylactic acid filaments are opened and spread, and then are sprayed with a plasticizer glyceryl triacetate in an atomized form through a filter rod forming machine glue tank; the spraying amount is 6% of the mass of the polylactic acid filaments; then the filaments are wrapped and formed, cut and obtained as the polylactic acid cigarette filter rod.

[0033] Example 4: A preparation method of a polylactic acid cigarette filter rod, comprising the following steps: (1) preparing an amino-terminated hyperbranched polymer: the method is the same as that in Example 1; (2) preparing a cellulose diacetate grafted hyperbranched polymer: at room temperature, 100 g of cellulose diacetate, 10 g of the amino-terminated hyperbranched polymer and 200 mL of dichloromethane solvent are added into a flask, the system is heated to 60°C, and the reaction is carried out under nitrogen protection for 6 h; vacuum drying is performed to remove the solvent, and the cellulose diacetate grafted hyperbranched polymer is obtained; (3) preparing modified polylactic acid particles: polylactic acid (weight average molecular weight 150000), cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate (Mw=9.84 x 10 4) and antioxidant were mixed uniformly to obtain a premix, the premix was melt-extruded through a twin-screw extruder to obtain modified polylactic acid particles; the antioxidant was pentaerythritol tetrakis [beta-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and tris(2,4-di-tert-butylphenyl) phosphite at a mass ratio of 2:3; (4) Preparation of polylactic acid filament: the modified polylactic acid particles were spun into Y-shaped filaments through a spinning machine, and were subjected to a drawing, crimping and heat setting process to prepare polylactic acid filaments; the temperature of the spinning box was 230°C, the drawing temperature was 90°C, and the drawing ratio was 6 times; (5) The polylactic acid filaments were opened and spread, and then passed through the glue box of a filter rod forming machine, the plasticizer glyceryl triacetate was sprayed on the polylactic acid filaments in the form of atomization, the spraying amount was 6% of the mass of the polylactic acid filaments; then the filaments were wrapped and formed, cut and obtained the polylactic acid cigarette filter rod.

[0034] Example 5: A method for preparing a polylactic acid cigarette filter rod, comprising the following steps: (1) Preparation of amino-terminated hyperbranched polymer: the method is the same as that in Example 1; (2) Preparation of cellulose diacetate grafted hyperbranched polymer: 100 g of cellulose diacetate, 10 g of amino-terminated hyperbranched polymer and 200 mL of dichloromethane solvent were added into a flask at room temperature, the system was heated to 60°C, and reacted for 6 h under nitrogen protection, and then vacuum drying was performed to remove the solvent to obtain the cellulose diacetate grafted hyperbranched polymer; (3) Preparation of modified polylactic acid particles: polylactic acid (weight average molecular weight 150000), cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate (Mw = 9.84 x 10 4 ) and antioxidant were mixed uniformly to obtain a premix, the premix was melt-extruded through a twin-screw extruder to obtain modified polylactic acid particles; the antioxidant was pentaerythritol tetrakis [beta-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and tris(2,4-di-tert-butylphenyl) phosphite at a mass ratio of 2:3; (4) Preparation of polylactic acid filament: the modified polylactic acid particles were spun into Y-shaped filaments through a spinning machine, and were subjected to a drawing, crimping and heat setting process to prepare polylactic acid filaments; the temperature of the spinning box was 230°C, the drawing temperature was 90°C, and the drawing ratio was 6 times; (5) The polylactic acid filaments were opened and spread, and then passed through the glue box of a filter rod forming machine, the plasticizer glyceryl triacetate was sprayed on the polylactic acid filaments in the form of atomization, the spraying amount was 6% of the mass of the polylactic acid filaments; then the filaments were wrapped and formed, cut and obtained the polylactic acid cigarette filter rod.

[0035] Example 6: A preparation method of a polylactic acid cigarette filter rod, comprising the following steps: (1) preparing an amino-terminated hyperbranched polymer: the method is the same as that in Example 1; (2) preparing a cellulose diacetate grafted hyperbranched polymer: at room temperature, 100 g of cellulose diacetate, 10 g of the amino-terminated hyperbranched polymer and 200 mL of dichloromethane solvent are added into a flask, the system is heated to 60°C, and reaction is carried out under nitrogen protection for 6 h; vacuum drying is performed to remove the solvent, and the cellulose diacetate grafted hyperbranched polymer is obtained; (3) preparing modified polylactic acid particles: polylactic acid (weight average molecular weight 150000), cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate (Mw=9.84 x 10 4 ) and an antioxidant are uniformly mixed in a mass ratio of 70:15:15:0.5 to obtain a premix, and the premix is melt-extruded through a double-screw extruder to obtain the modified polylactic acid particles; the antioxidant is tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester and tris(2,4-di-tert-butylphenyl)phosphite in a mass ratio of 2:3; (4) preparing polylactic acid filaments: the modified polylactic acid particles are spun into Y-shaped filaments through a spinning machine, and are subjected to a drawing, crimping and heat setting process to prepare the polylactic acid filaments; the temperature of the spinning box is 230°C, the drawing temperature is 90°C, and the drawing ratio is 6 times; (5) the polylactic acid filaments are opened and spread, and then are sprayed with a plasticizer glyceryl triacetate in an atomized form through a filter rod forming machine glue tank; the spraying amount is 6% of the mass of the polylactic acid filaments; then the filaments are wrapped and formed, cut and obtained as the polylactic acid cigarette filter rod.

[0036] Example 7: A preparation method of a polylactic acid cigarette filter rod, comprising the following steps: (1) preparing an amino-terminated hyperbranched polymer: the method is the same as that in Example 1; (2) preparing a cellulose diacetate grafted hyperbranched polymer: at room temperature, 100 g of cellulose diacetate, 10 g of the amino-terminated hyperbranched polymer and 200 mL of dichloromethane solvent are added into a flask, the system is heated to 60°C, and reaction is carried out under nitrogen protection for 6 h; vacuum drying is performed to remove the solvent, and the cellulose diacetate grafted hyperbranched polymer is obtained; (3) preparing modified polylactic acid particles: polylactic acid (weight average molecular weight 150000), cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate (Mw=9.84 x 10 4) and antioxidant were mixed uniformly to obtain a premix, the premix was melt-extruded through a twin-screw extruder to obtain modified polylactic acid particles; the antioxidant was pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and tris(2,4-di-tert-butylphenyl) phosphite at a mass ratio of 2:3; (4) Preparation of polylactic acid filament: the modified polylactic acid particles were spun into Y-shaped filaments through a spinning machine, and were subjected to a drawing, crimping and heat setting process to prepare polylactic acid filaments; the temperature of the spinning box was 230°C, the drawing temperature was 90°C, and the drawing ratio was 6 times; (5) The polylactic acid filaments were opened and spread, and then passed through the glue tank of a filter rod forming machine, the plasticizer glyceryl triacetate was sprayed on the polylactic acid filaments in the form of atomization, the spraying amount was 6% of the mass of the polylactic acid filaments; then the filaments were wrapped and formed, cut and obtained the polylactic acid cigarette filter rod.

[0037] Example 8: A method for preparing a polylactic acid cigarette filter rod, comprising the following steps: (1) Preparation of amino-terminated hyperbranched polymer: the method is the same as that in Example 1; (2) Preparation of cellulose diacetate grafted hyperbranched polymer: 100 g of cellulose diacetate, 15 g of amino-terminated hyperbranched polymer and 200 mL of dichloromethane solvent were added into a flask at room temperature, the system was heated to 60°C, and reacted for 6 h under nitrogen protection, and then vacuum drying was performed to remove the solvent to obtain the cellulose diacetate grafted hyperbranched polymer; (3) Preparation of modified polylactic acid particles: polylactic acid (weight average molecular weight 150000), cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate (Mw = 9.84 x 10 4 ) and antioxidant were mixed uniformly to obtain a premix, the premix was melt-extruded through a twin-screw extruder to obtain modified polylactic acid particles; the antioxidant was pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and tris(2,4-di-tert-butylphenyl) phosphite at a mass ratio of 2:3; (4) Preparation of polylactic acid filament: the modified polylactic acid particles were spun into Y-shaped filaments through a spinning machine, and were subjected to a drawing, crimping and heat setting process to prepare polylactic acid filaments; the temperature of the spinning box was 230°C, the drawing temperature was 90°C, and the drawing ratio was 6 times; (5) The polylactic acid filaments were opened and spread, and then passed through the glue tank of a filter rod forming machine, the plasticizer glyceryl triacetate was sprayed on the polylactic acid filaments in the form of atomization, the spraying amount was 6% of the mass of the polylactic acid filaments; then the filaments were wrapped and formed, cut and obtained the polylactic acid cigarette filter rod.

[0038] Example 9: A preparation method of a polylactic acid cigarette filter rod, comprising the following steps: (1) preparing an amino-terminated hyperbranched polymer: the method is the same as that in Example 1; (2) preparing cellulose diacetate grafted hyperbranched polymer: 100 g of cellulose diacetate, 20 g of amino-terminated hyperbranched polymer and 200 mL of dichloromethane solvent are added into a flask at room temperature, the system is heated to 60°C, and the reaction is carried out for 6 h under nitrogen protection, and then vacuum drying is performed to remove the solvent to obtain the cellulose diacetate grafted hyperbranched polymer; (3) preparing modified polylactic acid particles: polylactic acid (weight average molecular weight 150000), cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate (Mw=9.84×10 4 ) and antioxidant are uniformly mixed at a mass ratio of 75:15:10:0.5 to obtain a premix, and the premix is melt-extruded through a double-screw extruder to obtain the modified polylactic acid particles; the antioxidant is tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester and tris(2,4-di-tert-butylphenyl)phosphite at a mass ratio of 2:3; (4) preparing polylactic acid tow: the modified polylactic acid particles are spun into Y-shaped tow through a spinning machine, and then subjected to a drawing, crimping and heat setting process to obtain the polylactic acid tow; the spinning box temperature is 230°C, the drawing temperature is 90°C, and the drawing ratio is 6 times; (5) the polylactic acid tow is opened and spread, and then passed through a filter rod forming machine glue box, and a plasticizer glycerol triacetate is sprayed on the polylactic acid tow in an atomized form, and the spraying amount is 6% of the mass of the polylactic acid tow; then the tow is wrapped and formed, cut and obtained to obtain the polylactic acid cigarette filter rod.

[0039] Comparative Example 1 (without adding cellulose diacetate grafted hyperbranched polymer and PPC): A preparation method of a polylactic acid cigarette filter rod, comprising the following steps: (1) preparing polylactic acid particles: polylactic acid (weight average molecular weight 150000) and antioxidant are uniformly mixed at a mass ratio of 75:0.5 to obtain a premix, and the premix is melt-extruded through a double-screw extruder to obtain the polylactic acid particles; the antioxidant is tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester and tris(2,4-di-tert-butylphenyl)phosphite at a mass ratio of 2:3; (2) preparing polylactic acid tow: the polylactic acid particles are spun into Y-shaped tow through a spinning machine, and then subjected to a drawing, crimping and heat setting process to obtain the polylactic acid tow; the spinning box temperature is 230°C, the drawing temperature is 90°C, and the drawing ratio is 6 times; (3) The poly-lactic-acid tow is opened and spread, and then passed through the glue box of a filter rod forming machine. A plasticizer, triacetin, is sprayed on the poly-lactic-acid tow in the form of atomized mist, and the spraying amount is 6% of the mass of the poly-lactic-acid tow. Then the tow is wrapped and formed, cut, and the poly-lactic-acid cigarette filter rod is obtained.

[0040] Comparative Example 2 (without grafting hyperbranched polymer): A method for preparing a poly-lactic-acid cigarette filter rod comprises the following steps: (1) Preparation of modified poly-lactic-acid particles: poly-lactic-acid (weight average molecular weight 150000), cellulose diacetate, polypropylene carbonate (Mw = 9.84 x 10 4 ) and antioxidant are mixed in a mass ratio of 75:15:10:0.5 to obtain a premix, and the premix is melt-extruded through a double-screw extruder to obtain modified poly-lactic-acid particles; the antioxidant is a mixture of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester and tri(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 2:3; (2) Preparation of poly-lactic-acid tow: the modified poly-lactic-acid particles are spun into Y-shaped tow through a spinning machine, and then subjected to drawing, crimping and heat setting processes to obtain poly-lactic-acid tow; the spinning box temperature is 230°C, the drawing temperature is 90°C, and the drawing ratio is 6 times; (3) The poly-lactic-acid tow is opened and spread, and then passed through the glue box of a filter rod forming machine. A plasticizer, triacetin, is sprayed on the poly-lactic-acid tow in the form of atomized mist, and the spraying amount is 6% of the mass of the poly-lactic-acid tow. Then the tow is wrapped and formed, cut, and the poly-lactic-acid cigarette filter rod is obtained.

[0041] Comparative Example 3 (without adding PPC): A method for preparing a poly-lactic-acid cigarette filter rod comprises the following steps: (1) Preparation of amino-terminated hyperbranched polymer: the method is the same as that in Example 1; (2) Preparation of cellulose diacetate-grafted hyperbranched polymer: the method is the same as that in Example 2; (3) Preparation of modified poly-lactic-acid particles: poly-lactic-acid (weight average molecular weight 150000), cellulose diacetate-grafted hyperbranched polymer and antioxidant are mixed in a mass ratio of 85:15:0.5 to obtain a premix, and the premix is melt-extruded through a double-screw extruder to obtain modified poly-lactic-acid particles; the antioxidant is a mixture of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester and tri(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 2:3; (4) Preparation of poly-lactic-acid tow: the modified poly-lactic-acid particles are spun into Y-shaped tow through a spinning machine, and then subjected to drawing, crimping and heat setting processes to obtain poly-lactic-acid tow; the spinning box temperature is 230°C, the drawing temperature is 90°C, and the drawing ratio is 6 times; (5) the PLA filaments are opened and spread, then passed through the glue box of a filter rod forming machine, and glyceryl triacetate is sprayed on the PLA filaments in an atomized form, with a spraying amount of 6% of the mass of the PLA filaments; then the filaments are wrapped and formed, cut, and the PLA cigarette filter rod is obtained.

[0042] The performance of the cigarette filter rods prepared in the above examples and comparative examples is tested, and the results are shown in Table 1.

[0043] wherein the suction resistance effect of the filter rod is determined according to GB / T 22838.5-2009; The filter rod hardness is tested according to GB / T 22838.6-2009; The strength of the filaments is tested according to YC / T 169.5-2009; The moisture regain of the filter rod is tested according to YC / T 169.7-2009.

[0044] Table 1: Performance test results of the cigarette filter rod.

[0045] It can be seen from the data in Table 1 that the PLA filter rods prepared by the method of the present application in Examples 1-9 meet the standard of cigarette filter rods, and the suction resistance and hardness both meet the requirements, and the comprehensive performance of Example 5 is the best.

[0046] The pure PLA filter rod in Comparative Example 1 without adding cellulose diacetate grafted hyperbranched polymer and PPC has insufficient hardness of the filter rod due to poor reactivity of PLA and glyceryl triacetate. In Comparative Example 2, cellulose diacetate is not grafted with hyperbranched polymer, and the dispersion effect of cellulose acetate in PLA is poor, and the decomposition temperature is low, so the suction resistance of the filter rod increases and the hardness decreases. In Comparative Example 3, no PPC is added, and the hardness of the filter rod also decreases.

[0047] The PLA filter rod prepared by the present application has the following advantages: 1. The glyceryl triacetate can solidify the PLA fibers, and the PLA filter rod has a certain hardness; 2. The filtration effect of the PLA filter rod on smoke is not much different from that of the cellulose acetate filter rod, and the cost is lower.

[0048] The examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A polylactic acid filament tow for use in cigarette filters, characterized in that, The raw materials include polylactic acid, cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate, and antioxidants; The cellulose diacetate grafted hyperbranched polymer is prepared by reacting cellulose diacetate with an amino-terminated hyperbranched polymer.

2. The polylactic acid filament tow for cigarette filters according to claim 1, characterized in that, The mass ratio of cellulose diacetate to the amino-terminated hyperbranched polymer is 1:0.05~0.

2.

3. The polylactic acid filament tow for cigarette filters according to claim 1 or 2, characterized in that, The mass ratio of polylactic acid, cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate, and antioxidant is 65~90:5~20:5~15:0.

5.

4. The polylactic acid filament tow for cigarette filters according to claim 1, characterized in that, The antioxidant is two or more of the following: β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite, β-octadecyl propionate, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and tris(2,4-di-tert-butylphenyl)phosphite.

5. A method for preparing polylactic acid filament tow for cigarette filters as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Preparation of cellulose diacetate grafted hyperbranched polymer; (2) Preparation of modified polylactic acid particles: Polylactic acid, cellulose diacetate grafted hyperbranched polymer, polypropylene carbonate and antioxidant are mixed and melt-extruded to obtain modified polylactic acid particles; (3) Preparation of polylactic acid filament bundles: Modified polylactic acid particles are spun into Y-shaped filament bundles by a spinning machine, and then subjected to stretching, crimping and heat setting processes to produce polylactic acid filament bundles.

6. The method for preparing polylactic acid filament tow for cigarette filters according to claim 5, characterized in that, The preparation method of cellulose diacetate grafted hyperbranched polymer in step (1) is as follows: cellulose diacetate and amino-terminated hyperbranched polymer are dissolved in an organic solvent, the system is heated to 40~80℃, reacted under nitrogen protection for 5~7h, and the solvent is removed by vacuum drying to obtain the cellulose diacetate grafted hyperbranched polymer.

7. The method for preparing polylactic acid filament tow for cigarette filters according to claim 5, characterized in that, The spinning temperature in step (3) is 220℃~250℃.

8. The method for preparing polylactic acid filament tow for cigarette filters according to claim 5 or 7, characterized in that, The temperature during stretching in step (3) is 80~100℃, and the stretching ratio is 5~7 times.

9. An application of polylactic acid tow for cigarette filters as described in any one of claims 1 to 4, characterized in that, Used to prepare polylactic acid cigarette filter rods.

10. The application of the polylactic acid tow for cigarette filters according to claim 9, characterized in that, The preparation method of polylactic acid cigarette filter rod is as follows: after the polylactic acid filament tow is opened and spread, it is passed through the glue box of the filter rod forming machine. The plasticizer triacetin is sprayed onto the polylactic acid filament tow in an atomized form. Then the filament tow is rolled into shape, cut, and the polylactic acid cigarette filter rod is obtained.

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