A method for preparing a polylactic acid fiber hollow filter rod

Abstract

The application provides a preparation method of a polylactic acid fiber hollow filter rod, and relates to the technical field of hollow filter rods, and comprises the following steps: after polylactic acid fiber tows are loosened, the polylactic acid fiber tows are sent into a forming cavity, and the polylactic acid fiber tows are heated and solidified by using heated air to form a polylactic acid fiber hollow filter rod. The polylactic acid fiber tows are heated by using the hot air heating mode, and the polylactic acid fiber hollow filter rod is obtained after solidification forming, and the forming effect is good, the regularity is good, and the pollution is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hollow filter rods, in particular, the present application relates to a preparation method of polylactic acid fiber hollow filter rod. BACKGROUND

[0002] With the development of cigarette production technology, the types and appearance of cigarettes are more diversified, and cigarettes with unique shapes are more likely to be loved by people, thereby giving birth to a new type of filter rod, hollow filter rod.

[0003] The production of hollow (hollow) filter rods with acetate fiber tows is a mature process technology, mostly using high-temperature steam heating to quickly solidify into filter rods. For example, Chinese patent invention patent CN111436650A discloses a preparation method of a hollow cooling filter rod, which is composed of a tow, a cooling material and a curing agent. On the wire drawing hollow filter rod forming machine, the corresponding mold is used, and the production process of high-temperature steam accelerated curing is used to prepare it. The external solid part of the filter rod is a smooth cylindrical structure, which has a certain elasticity and hardness, and is suitable for cigarette tipping; the internal hollow part is a straight-through cavity structure with a shape similar to a corrugated pipe, which has good heat transfer and cooling effect when the smoke passes through it; because the filter rod is a straight-through structure, it also has very low resistance, which is used for new tobacco. When cooling, the atomization amount of the cigarette is doubled, which meets the experience of the smoker and provides a new solution for improving the quality of cigarettes and developing new tobacco products.

[0004] Because polylactic acid has the advantages of low price, easy degradation and no pollution compared with acetate fiber, the preparation and research of polylactic acid filter rod are very important now; but the current process technology for producing hollow (hollow) filter rods with polylactic acid tows is indeed very lacking.

[0005] Moreover, polylactic acid PLA is a thermoplastic aliphatic polyester with a low glass transition temperature, which will appear rigidification and thermal collapse under high temperature conditions. In the initial stage of producing hollow (hollow) filter rods with polylactic acid tows, steam heating method is also used to trial-produce filter rods, but the steam temperature is too high, the effect is not good, the shape of the filter rod is irregular, and normal production is impossible.

[0006] Therefore, it is necessary for us to design a reasonable and efficient preparation method of polylactic acid fiber hollow filter rod to solve the above problems. SUMMARY

[0007] The purpose of the present application is to provide a preparation method of polylactic acid fiber hollow filter rod, which heats the polylactic acid fiber tow by hot air heating, and obtains the polylactic acid fiber hollow filter rod after solidification and molding, which has good molding effect, good regularity and low pollution.

[0008] To achieve the above object, the present application adopts the following technical solutions to achieve the above object:

[0009] A preparation method of a polylactic acid fiber hollow filter rod, the method comprising the following steps:

[0010] After the polylactic acid fiber tows are opened, they are sent into a forming cavity, and the polylactic acid fiber tows are heated and solidified by the heated air to obtain a polylactic acid fiber hollow filter rod.

[0011] As a preferred embodiment of the present application, the temperature of the heated air ranges from 65 DEG C to 85 DEG C.

[0012] As a preferred embodiment of the present application, when the heated air enters the forming cavity, the air pump is pressurized, and the air pump is electrically connected to the temperature sensor in the forming cavity, so that the real-time temperature in the forming cavity is obtained to adjust the output power of the air pump, so that the temperature in the forming cavity ranges from 65 DEG C to 85 DEG C.

[0013] As a preferred embodiment of the present application, a forming inner core is arranged in the forming cavity, and the cross-sectional shape of the forming inner core includes peach heart, pentagram, circle and plum blossom, so that the polylactic acid fiber hollow filter rod formed has a corresponding shape of the middle hole.

[0014] As a preferred embodiment of the present application, the air is filtered before being heated.

[0015] As a preferred embodiment of the present application, the specification of the polylactic acid tows ranges from 60000 d to 66000 d.

[0016] As a preferred embodiment of the present application, two polylactic acid tows are opened at the same time, and the specification of each polylactic acid tow ranges from 30000 d to 33000 d.

[0017] As a preferred embodiment of the present application, the amount of triacetin applied when the polylactic acid fiber tows are formed ranges from 12% to 16%.

[0018] The preparation method of the polylactic acid fiber hollow filter rod has the advantages that the polylactic acid fiber tows are heated by the heated air, and the polylactic acid fiber hollow filter rod is obtained after solidification and forming, so that the forming effect is good, the regularity is good, and the pollution is low. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1The preparation process schematic diagram of one embodiment of the preparation method of the polylactic acid fiber hollow filter rod. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the accompanying drawings in the embodiments of the present application.

[0022] In the following description, the terms "first", "second", etc. are used only for the purpose of description, and cannot be understood as indicating or implying relative importance. The following description provides a plurality of embodiments of the present application, and different embodiments can be replaced or combined, so the present application can also be considered to include all possible combinations of the same and / or different embodiments described. Therefore, if one embodiment includes features A, B and C, and another embodiment includes features B and D, the present application should also be considered to include an embodiment including one or more all other possible combinations of A, B, C and D, although the embodiment may not be explicitly described in the following content.

[0023] The following description provides examples and does not limit the scope, applicability or examples set forth in the claims. Changes can be made to the functions and arrangements of described elements without departing from the scope of the present application. Various examples can appropriately omit, replace or add various processes or components. For example, the described methods can be performed in different order from the described order, and various steps can be added, omitted or combined. In addition, features described with respect to some examples can be combined into other examples.

[0024] Embodiment: please refer to Figure 1 The preparation method of the polylactic acid fiber hollow filter rod, the method comprises the following steps:

[0025] After the polylactic acid fiber tows are opened, they are sent into the forming cavity, and the polylactic acid fiber tows are heated and cured by the heated air to obtain the polylactic acid fiber hollow filter rod.

[0026] In the present application, the heating forming process of the acetate filter rod is relatively perfect, but the heating forming process of polylactic acid is very lacking. Since polylactic acid has the advantages of low price, easy degradation and no pollution compared with acetate, the preparation and research of polylactic acid filter rod are very important. The focus of the present application is to heat and prepare the polylactic acid fiber hollow filter rod.

[0027] Further, since the acetate hollow filter rod mostly uses steam heating, the steam temperature can reach above 170 DEG C. Since polylactic acid is a thermoplastic aliphatic polyester, the glass transition temperature is low, and under high temperature conditions, the conditions of stiffening and thermal collapse will occur, so the use of high temperature steam heating for polylactic acid hollow filter rod preparation and forming effect is very poor.

[0028] After many experiments and summary, it is found that the heating preparation of polylactic acid hollow filter rod requires a temperature less than 100℃, and the steam will condense into water, which cannot be used for steam heating method.

[0029] Therefore, we creatively propose to directly use air heating to prepare polylactic acid hollow filter rod, and the experimental verification has high feasibility, as follows:

[0030] The pure air is heated to a predetermined temperature, and then contacted with the opened polylactic acid fiber tows sent to the forming unit to heat and solidify the polylactic acid fiber tows to form polylactic acid filter rods.

[0031] Specifically, the polylactic acid fiber tows are opened and then reach the forming cavity, and the heated air is also input into the forming cavity, so that the polylactic fiber tows are contacted with the hot air, and the polylactic fiber tows are heated and solidified, and finally the polylactic acid filter rods are formed.

[0032] Since we need to prepare polylactic acid hollow filter rods, a forming inner core should be provided in the forming cavity, and the polylactic acid fiber tows can reach the space between the outside of the forming inner core and the inside of the forming cavity, and contact with the heated air to form polylactic acid hollow filter rods with hollow holes (the shape depends on the structure of the forming inner core).

[0033] Of course, the cross-sectional shape of the forming inner core includes peach heart, pentagram, circle and plum blossom, so that the polylactic acid fiber hollow filter rods formed have corresponding shaped middle holes.

[0034] In addition, the air reaching the forming cavity needs to be pure and the temperature reaches a predetermined temperature, so the air is filtered before heating, that is, the air needs to be filtered by a filter bin first to ensure that it meets the standard of pure air, and then the pure air is heated and input into the forming cavity.

[0035] Of course, the above-mentioned predetermined temperature, that is, the heating temperature of polylactic acid, that is, the temperature range of the air reaching the forming cavity after heating, is 65℃ to 85℃.

[0036] The experiment investigated the influence of different hot air temperatures on filter rod forming production and filter rod physical indicators and appearance, and the results are as follows:

[0037] Table 1.1 Influence of different hot air temperatures on polylactic acid forming (24.0mm x 120mm)

[0038]

[0039] That is, the production of hollow tube (hollow) filter rod with polylactic acid filament, when the hot air temperature is below 60℃, due to the filter rod in the molding process can not be quickly solidified, production is not good, the filter rod deformation, poor roundness, low hardness; hot air temperature is 65~85℃, production is normal, filter rod index and appearance are in line with the requirements; when the hot air temperature is more than 90℃, the production is poor, the roundness and concentricity of the filter rod are poor. Therefore, the production of hollow tube (hollow) filter rod, the hot air temperature is 65~85℃, which is far lower than the high temperature steam temperature used in the preparation of acetate filter rod.

[0040] Of course, the inner side wall of the heating bin is provided with electric heating wire and temperature sensor electrically connected with the electric heating wire, and once the temperature deviates from the interval of 65~85℃, an alarm is sent in time.

[0041] When the heated air enters the molding cavity, the air pump is pressurized, and the air pump is electrically connected with the temperature sensor in the molding cavity. By acquiring the real-time temperature in the molding cavity, the output power of the air pump is adjusted, so that the temperature in the molding cavity is located between 65℃ and 85℃.

[0042] For example, when the temperature sensor senses that the temperature in the molding cavity decreases, the air pump power is increased to increase the input flow of hot air to increase the temperature in the cavity; if the temperature continues to decrease below 65℃, an alarm is sent.

[0043] In summary, the pure air filtered through the filter bin under the drive of the air pump is heated in the heating bin, and the heated air finally reaches the polylactic acid fiber filament in the molding cavity to achieve the molding effect of the polylactic acid fiber hollow filter rod.

[0044] In addition, during the preparation of polylactic acid hollow filter rod, a camera and a sensor are arranged at the molding cavity to timely check the polylactic acid fiber filament supply condition and timely send an alarm when abnormal.

[0045] It should be noted that the specification of the polylactic acid fiber filament supply at the molding cavity is preferably 30000d×2~33000d×2 (equivalent to 60000~66000d).

[0046] The experiment investigated the influence of different hot air temperatures on filter rod molding production and filter rod physical index and appearance, and the results are as follows:

[0047] Table 1.2 Different total denier polylactic acid filament molding conditions (24.0mm×120mm)

[0048]

[0049]

[0050] That is, the production of conventional hollow (hollow) filter rods using polylactic acid filament is poor when the total denier of the filament is below 26000d x 2 (i.e. 52,000 denier), the filter rod roundness is poor, and the hardness is low; the production is normal when the total denier of the filament is between 30000d x 2 and 33000d x 2 (equivalent to 60000-66000d), the filter rod indexes and appearance meet the requirements; the production becomes poor when the total denier of the filament exceeds 35000d x 2 (i.e. 70,000 denier), and the filter rod index fluctuation becomes large. Therefore, for the production of conventional hollow (hollow) filter rods, the specification of polylactic acid filament is preferably between 30000d x 2 and 33000d x 2 (equivalent to 60000-66000d).

[0051] Preferably, two polylactic acid filaments are opened at the same time during opening, and the specification of each polylactic acid filament is between 30000d and 33000d.

[0052] In addition, during the preparation of the polylactic acid hollow filter rod, an application port for applying triacetin is arranged at the forming cavity, and triacetin needs to be applied to the polylactic acid fiber filament to improve the forming effect.

[0053] The amount of triacetin applied to the polylactic acid fiber filament during forming is between 12% and 16%.

[0054] The effects of different amounts of triacetin on the forming, production, physical indexes and appearance of the filter rod were investigated by experiments, and the results are as follows:

[0055] Table 1.3 Effects of different amounts of triacetin on forming (24.0mm x 120mm)

[0056]

[0057]

[0058] That is, the production of hollow (hollow) filter rods using polylactic acid filament is acceptable when the amount of triacetin applied is below 10%, but the formed filter rod is not formed, and the hardness is low; the production is normal when the amount of triacetin applied is between 12% and 16%, and the filter rod indexes and appearance meet the requirements; the production becomes poor when the amount of triacetin applied exceeds 18%, and the filter rod index fluctuation becomes large. Therefore, for the production of polylactic acid hollow (hollow) filter rods, the amount of triacetin applied is preferably between 12% and 16%.

[0059] The preparation method of the polylactic acid fiber hollow filter rod of the present application heats the polylactic acid fiber filament by hot air heating, and obtains the polylactic acid fiber hollow filter rod after solidification and forming, which has good forming effect, good regularity and low pollution.

[0060] The above descriptions are merely some example embodiments of the present disclosure, and cannot limit the scope of the present disclosure. That is, equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. Those skilled in the art will easily derive other embodiments of the present disclosure upon considering the specification and practicing the disclosure herein. The present application is intended to cover any variations, uses, or adaptive changes of the present disclosure following the general principles of the present disclosure and including common knowledge or conventional technical means in the art not described in the present disclosure. The specification and examples are merely considered as exemplary, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A method of producing a polylactic acid fiber hollow filter rod, characterized by: The method comprises the following steps: After the poly-lactic acid fiber tows are loosened, the poly-lactic acid fiber tows are sent into a forming cavity, the poly-lactic acid fiber tows are heated and solidified by the heated air to form poly-lactic acid fiber hollow filter rods; The temperature of the heated air ranges from 65℃ to 85℃; A forming inner core is arranged in the forming cavity, and the poly-lactic acid fiber tows contact the heated air in the space between the outside of the forming inner core and the inside of the inner wall of the forming cavity; The specification of the poly-lactic acid fiber tows ranges from 30000d×2 to 33000d×2; two poly-lactic acid fiber tows are loosened at the same time, and the specification of each poly-lactic acid fiber tow ranges from 30000d to 33000d; When the poly-lactic acid fiber tows are formed, the amount of triacetin applied ranges from 12% to 16%; The poly-lactic acid fiber hollow filter rods with good roundness, concentricity and normal hardness are obtained.

2. The preparation method of the poly-lactic acid fiber hollow filter rod according to claim 1, characterized in that: When the heated air enters the forming cavity, the air pump is pressurized, and the air pump is electrically connected with the temperature sensor in the forming cavity; the real-time temperature in the forming cavity is obtained to adjust the output power of the air pump, so that the temperature in the forming cavity ranges from 65℃ to 85℃.

3. The preparation method of the poly-lactic acid fiber hollow filter rod according to claim 1, characterized in that: The cross-sectional shape of the forming inner core includes peach heart, pentagram, circle and plum blossom, so that the poly-lactic acid fiber hollow filter rods formed have corresponding shapes of the middle holes.

4. The preparation method of the poly-lactic acid fiber hollow filter rod according to claim 1, characterized in that: Before the air is heated, the air is filtered.

Images