Group-processed polylactic acid fiber filter rods and their manufacturing method

Abstract

The present invention provides a polylactic acid fiber filter rod processed by group processing and its manufacturing method, which relates to the technical field of cigarette manufacturing. The polylactic acid fiber filter rod includes an inner core and an outer skin, the inner core and the outer skin are each composed of a plurality of polylactic acid fiber tows, the polylactic acid fiber tows in the inner core are made of a first component raw material, the polylactic acid fiber tows in the outer skin are made of a second component raw material, the content of L-lactic acid monomer in the first component raw material is higher than that in the second component raw material, a dispersant is added to the first component raw material, and glycerol triacetate is added to the second component raw material. The present invention is easy to install, and by strictly controlling the properties of the polylactic acid raw materials, all the outer layer skins have a uniform crystallinity, and all the inner layer cores also have a uniform crystallinity. When the tow crystallizes, the nodes are evenly distributed, and the inside and outside of the produced polylactic acid fiber filter rod have gradually changing crystallinity, so the processing process is more stable and the adsorption performance of the filter rod is ensured.

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of tobacco manufacturing, and in particular, the present invention relates to a polylactic acid fiber filter rod processed in groups and a method for manufacturing the same. BACKGROUND ART

[0002] Polylactic acid (PLA) is a polymer material produced by chemical synthesis after obtaining lactic acid through fermenting starch from renewable plant resources, which has excellent recyclability and biodegradability, and has the following characteristics. 1. Using renewable plant resources (such as corn, wheat, sugar beet, rice, potato, taro, etc.) and organic waste (such as corn cobs or roots, stems, leaves and husks of other crops) as raw materials, it is free from dependence on wood and petroleum resources and meets the requirements of sustainable development. 2. It is completely biodegradable, and can naturally decompose into water and carbon dioxide after a certain period of time in the natural environment without causing environmental pollution; the generated carbon dioxide is reused through photosynthesis of plants, forming an eternal closed carbon cycle system, so it is a real "green material". 3. Compared with the three synthetic fibers of polyester, nylon and acrylic, the energy consumption for producing polylactic acid fiber is relatively low, so it is a polymer material with relatively low impact on resources and the environment. 4. It has good processing performance, and tows can be produced by using common melt spinning methods for thermoplastic resins.

[0003] Currently, polylactic acid fibers are being developed for applications such as cigarette tows, but the performance requirements for polylactic acid fibers used in cigarette tows differ significantly from those for conventional clothing. For example, clothing polylactic acid fibers must meet the requirements for fiber spinning, weaving, printing and dyeing of fabrics, washing, and ironing. They must possess very high crystallinity, orientation, and mechanical strength, withstand temperatures of 80-100°C, not dissolve or swell in detergent solutions or dry cleaning solvents, have a certain degree of hygroscopicity, and at the same time, the less adsorption of other gaseous substances from the surrounding environment, the better. However, as cigarette tows, they must meet the following requirements: (1) The wound filter rod is non-toxic, odorless, and safe. (2) The tow has good stability and can meet the filter rod molding device and process requirements. (3) Due to its appropriate rigidity and curling properties, it has good elasticity and opening properties, and when the tow filling amount is relatively small, the filter rod can meet certain requirements for hardness, suction resistance and appearance quality by adding a plasticizer or adhesive, and has a relatively high rod production rate. (4) It has sufficient heat resistance, and the filter tip does not collapse or deform during smoking of a rolled cigarette. (5) It has relatively high filtering efficiency against harmful components of smoke. (6) It does not affect the sensory quality of the rolled cigarette. Therefore, in order to meet the requirements for tobacco, it is necessary to develop dedicated spinning and post-processing technology.

[0004] For example, Chinese patent invention patent CN103074716A relates to a skin-core structured tow and filter rod for polylactic acid tobacco, and a method for manufacturing the same. The single fiber in the tow has a skin-core structure composed of an inner core and an outer skin, where both the resin of the skin layer and the core layer are polylactic acid, the weight ratio of the skin layer resin to the core layer resin is 20:80 to 40:60, the crystallinity of the skin layer and core layer of the tow is 3 to 25% and 25 to 60%, respectively, and the melting points of the skin layer and core layer are 120 to 150°C and 150 to 175°C, respectively. The above invention combines the advantages of both the core layer and the skin layer, with the core layer providing relatively high physical and mechanical performance and heat resistance, and the skin layer providing good adhesiveness. The filter rod can be easily molded using common plasticizers (such as glycerol triacetic acid). Furthermore, the polylactic acid tow with a skin core structure provided by the above invention has good biodegradability in both its core layer and skin layer, making it an environmentally friendly tow for tobacco.

[0005] However, the above-described filter rod manufacturing structure still suffers from the problem that the processing process of the polylactic acid tow in the above-described skin-core structure becomes unstable because both the skin layer resin and core layer resin are spun from a composite of various raw materials, and the properties of the polylactic acid raw materials are not controlled, resulting in relatively large differences in the degree of crystallinity, position and number of tow nodes among the various raw materials.

[0006] To solve the above problems, it is necessary to design a polylactic acid fiber filter rod processed in a rational and efficient group. [Overview of the Initiative]

[0007] The object of the present invention is to provide a polylactic acid fiber filter rod processed in a group that is easy to install, wherein by strictly controlling the properties of the polylactic acid raw material, all outer layer skins have a uniform degree of crystallinity, all inner layer cores also have a uniform degree of crystallinity, and when the tow crystallizes, the nodes are uniformly distributed, and the inside and outside of the manufactured polylactic acid fiber filter rod have a gradually changing degree of crystallinity, and the processing process is more stable.

[0008] To achieve the above objective, the present invention is realized using the following technical solutions. A polylactic acid fiber filter rod processed in a group, comprising an inner core and an outer skin installed outside the inner core, wherein both the inner core and the outer skin are composited with a plurality of polylactic acid fiber tows, the polylactic acid fiber tows of the inner core are manufactured from a first component raw material, and the polylactic acid fiber tows of the outer skin are manufactured from a second component raw material, the L-lactic acid monomer content in the first component raw material is higher than the L-lactic acid monomer content in the second component raw material, a dispersant is added to the first component raw material, and glycerol triacetic acid is added to the second component raw material, and the polylactic acid fiber tows of the inner core are subjected to draft stress to induce crystal formation in order to improve the crystallinity of the polylactic acid fiber tows of the inner core.

[0009] In a preferred embodiment of the present invention, the ratio range of the number of polylactic acid fibers in the inner core and outer skin is between 30:70 and 35:65.

[0010] In a preferred embodiment of the present invention, a nucleating agent is added to both the first component raw material and the second component raw material, and the content of the nucleating agent in the first component raw material is equal to or greater than the content of the nucleating agent in the second component raw material.

[0011] In a preferred embodiment of the present invention, a transition layer is provided between the inner core and the outer skin, the transition layer is composed of a plurality of polylactic acid fiber tows, and the content of L-lactic acid monomer in the component raw materials used for the polylactic acid fiber tows of the transition layer is less than or equal to the content of L-lactic acid monomer in the first component raw material, and greater than or equal to the content of L-lactic acid monomer in the second component raw material.

[0012] In a preferred embodiment of the present invention, the number of transition layers is at least two, and the content of L-lactic acid monomer in the raw material component used for the polylactic acid fiber tow of the transition layer closest to the inner core is equal to or greater than the content of L-lactic acid monomer in the raw material component used for the polylactic acid fiber tow of the transition layer closest to the outer skin.

[0013] In a preferred embodiment of the present invention, a nucleating agent is also added to the component raw material used in the polylactic acid fiber tow of the transition layer, and the content of the nucleating agent in the component raw material is less than or equal to the content of the nucleating agent in the first component raw material, and greater than or equal to the content of the nucleating agent in the second component raw material.

[0014] In a preferred embodiment of the present invention, an acetate fiber tow layer is provided on the outside of the outer skin layer.

[0015] The present invention relates to a method for manufacturing polylactic acid fiber filter rods processed in groups, S1: A step of obtaining polylactic acid having a first predetermined content of L-racemic mixture, adding a dispersant to obtain a first component raw material, inducing crystallization by draft stress during spinning of the first component raw material to obtain a first polylactic acid fiber tow, The steps include obtaining polylactic acid having a second predetermined value lower than the first predetermined value for S2:L-racemic content, adding glycerol triacetic acid to obtain a second component raw material, and spinning the second component raw material into a second polylactic acid fiber tow, The present invention further provides a manufacturing method comprising the steps of: S3: forming an inner core by compounding a plurality of first polylactic acid fiber tows; forming an outer skin by compounding a plurality of second polylactic acid fiber tows; and covering the outside of the inner core with the outer skin to form a polylactic acid fiber filter rod having a skin core structure.

[0016] In a preferred embodiment of the present invention, before performing step S3, polylactic acid having a third predetermined L-racemic content is obtained, a third polylactic acid fiber tow is obtained, and a plurality of third polylactic acid fiber tows are compounded to form a transition layer. When step S3 is executed, the transition layer covers the outside of the inner core, and the outer skin further covers the outside of the transition layer.

[0017] In a preferred embodiment of the present invention, after performing step S3, the outside of the outer layer skin is covered with an acetate fiber tow layer.

[0018] The beneficial effects of the polylactic acid fiber filter rods and their manufacturing methods processed by the group of the present invention are that they are easy to install, and by strictly controlling the properties of the polylactic acid raw material, all outer layer skins have a uniform degree of crystallinity, all inner layer cores also have a uniform degree of crystallinity, and when the tow crystallizes, the nodes are uniformly distributed, and the inside and outside of the manufactured polylactic acid fiber filter rod have a gradually changing degree of crystallinity, and the processing process is more stable. [Brief explanation of the drawing]

[0019] In the diagram: 1. Inner core, 2. Outer skin, 3. Transition layer, 4. Acetate fiber tow layer. [Figure 1] This is a cross-sectional view of one embodiment of a polylactic acid fiber filter rod processed by the group according to the present invention. [Figure 2] This is a flowchart of the method for manufacturing a polylactic acid fiber filter rod processed by the group according to the present invention. [Modes for carrying out the invention]

[0020] The following are specific examples of the present invention, which further illustrate the technical solutions of the present invention, but the present invention is not limited to these examples.

[0021] Various exemplary embodiments of the present invention will now be described in detail with reference to the drawings. It should be noted that, unless otherwise specified, the relative arrangement of modules and steps described in these examples does not limit the scope of the present invention.

[0022] Meanwhile, for the convenience of description, it should be understood that the processes shown in the drawings are not performed independently, and multiple steps are performed interleaved with each other.

[0023] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", and "outer" are either the directions or positional relationships shown in the drawings, or the conventionally arranged directions or positional relationships when the product of the present invention is used. These terms are only used to facilitate and simplify the description of the present invention, and do not indicate or imply that the mentioned device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions, and are not to be construed as indicating or implying relative importance.

[0024] The following description of at least one exemplary embodiment is substantially intended for illustrative purposes only, and is not intended to limit the present invention, its application, or its uses in any way.

[0025] Techniques, methods, and systems known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and systems should be considered part of the present specification.

[0026] Example 1: As shown in Figure 1, a polylactic acid fiber filter rod processed in a group comprises an inner core 1 and an outer skin 2 installed outside the inner core 1, both of which are composites of multiple polylactic acid fiber tows, the polylactic acid fiber tows of the inner core 1 being manufactured from a first component raw material, and the polylactic acid fiber tows of the outer skin 2 being manufactured from a second component raw material, wherein the L-lactic acid monomer content in the first component raw material is higher than the L-lactic acid monomer content in the second component raw material, a dispersant is added to the first component raw material, and glycerol triacetic acid is added to the second component raw material, and the polylactic acid fiber tows of the inner core 1 are subjected to draft stress to induce crystal formation in order to improve the crystallinity of the polylactic acid fiber tows of the inner core 1.

[0027] In this invention, polylactic acid having a first predetermined L-racemic content is obtained, a dispersant is added to obtain a first component raw material, crystallization is induced by draft stress during spinning of the first component raw material to obtain a first polylactic acid fiber tow, which has a higher degree of crystallinity and provides relatively high physical and mechanical properties and heat resistance, and by adding a dispersant, large nodes are less likely to form in the highly crystallinity first polylactic acid fiber tow, making slitting easier.

[0028] Generally, the range of the first predetermined value is 95% to 98%, meaning that the first component raw material contains 95% to 98% L-racemic mixture (i.e., L-lactic acid monomer). With such a high content of L-racemic mixture, the melting point of the first polylactic acid fiber tow also increases. In the spinning and post-processing processes, low-temperature crystallization is induced by draft stress, improving the degree of tow crystallization after drafting, improving the thermal stability of the tow size, making curling and shaping easier, and ensuring that the tow has appropriate rigidity and curling performance, as well as good elasticity and openness, and relatively low thermal shrinkage performance.

[0029] Similarly, polylactic acid having a second predetermined value lower than the first predetermined value is obtained, glycerol triacetic acid is added to obtain a second component raw material, and the second component raw material is spun into a second polylactic acid fiber tow. Although the second polylactic acid fiber tow has a slightly lower degree of crystallinity compared to the first polylactic acid fiber tow, the addition of glycerol triacetic acid provides greater swelling and adhesion performance.

[0030] The second predetermined value is less than or equal to the first predetermined value, and generally, the range of the second predetermined value is 92% to 95%. The second component raw material contains 92% to 95% L-racemic mixture, and it is necessary to add glycerol triacetic acid to the second component raw material. Under the action of glycerol triacetic acid, the second polylactic acid fiber tow swells and becomes adhesive, and finally, when combined with the first polylactic acid fiber tow obtained from the first component raw material, a polylactic acid tow with a skin core structure that has good adhesion can be obtained.

[0031] Finally, multiple first polylactic acid fiber tows are combined to form an inner core, multiple second polylactic acid fiber tows are combined to form an outer skin, and the outside of the inner core is covered with the outer skin to form a polylactic acid fiber filter rod having a skin core structure.

[0032] Here, the ratio range of the number of polylactic acid fiber tows in the inner core 1 and the outer skin 2 is between 30:70 and 35:65, meaning that the mass ratio of the core to the skin is within this range.

[0033] It should be noted that in polylactic acid fiber filter rods manufactured in the same batch, all primary raw materials are produced in the same location, batch, and undergo the same purification steps. In polylactic acid fiber filter rods manufactured in the same batch, all secondary raw materials are produced in the same location, batch, and undergo the same purification step.

[0034] It can be understood that in a single polylactic acid filter rod, or in a batch of polylactic acid filter rods manufactured simultaneously, all first polylactic acid fiber tows have the same properties, the degree of crystallinity of all manufactured first polylactic acid fiber tows is uniformly distributed, relatively large aggregates are less likely to form, and the alloy knife is less likely to be impacted or damaged during slitting, and that all second polylactic acid fiber tows also have the same properties.

[0035] In this way, by strictly controlling the properties of the polylactic acid raw material, all outer layer skins have a uniform degree of crystallinity, all inner layer cores also have a uniform degree of crystallinity, and when the tow crystallizes, the nodes are uniformly distributed, making the processing process more stable.

[0036] Furthermore, the crystallinity of the first polylactic acid fiber tow is higher than that of the second polylactic acid fiber tow, resulting in a gradually changing crystallinity on the inside and outside of the manufactured polylactic acid fiber filter rod, and the multilayer structure is processed in groups.

[0037] Here, the following meaning is extended: Since the raw materials for the polylactic acid fiber tou of the inner core and outer skin must be from the same production area, batch, and refining step, i.e., to guarantee uniqueness, the tobacco factory purchases two types of raw materials simultaneously. If they cannot be mixed and processed, they manufacture the two types of raw materials directly on two different production lines to obtain two different types of polylactic acid fiber tou. Based on a comparison of the L-lactic acid monomer content of the two types of raw materials, the raw material with a high L-lactic acid monomer content is manufactured according to the manufacturing method for the inner core, and the raw material with a low L-lactic acid monomer content is manufactured according to the manufacturing method for the outer skin. Finally, the inner and outer distributions of the two types of polylactic acid fiber tou are combined to achieve not only the uniqueness of the raw materials for a single layer, but also the gradual change in crystallinity between the inner and outer layers.

[0038] The polylactic acid fiber filter rods processed by the group according to the present invention are easy to install, and by strictly controlling the properties of the polylactic acid raw material, all outer layer skins have a uniform degree of crystallinity, all inner layer cores also have a uniform degree of crystallinity, and when the tow crystallizes, the nodes are uniformly distributed, and the inside and outside of the manufactured polylactic acid fiber filter rod have a gradually changing degree of crystallinity, and the processing process is more stable.

[0039] Example 2: Still as shown in Figure 1, this is still only one embodiment of the present invention, and in a polylactic acid fiber filter rod processed according to the group of the present invention based on Example 1, a nucleating agent is added to both the first component raw material and the second component raw material, and the content of the nucleating agent in the first component raw material is greater than or equal to the content of the nucleating agent in the second component raw material, further increasing the gradual change in the degree of crystallinity between the inside and outside of the polylactic acid fiber filter rod.

[0040] Furthermore, a transition layer 3 is provided between the inner core 1 and the outer skin 2, and the transition layer is made up of multiple polylactic acid fiber tows, and the content of L-lactic acid monomer in the component raw materials used for the polylactic acid fiber tows of the transition layer 3 is less than or equal to the content of L-lactic acid monomer in the first component raw material, and greater than or equal to the content of L-lactic acid monomer in the second component raw material.

[0041] In practice, there are at least two transition layers 3, and the L-lactic acid monomer content in the raw material components used for the polylactic acid fiber tow of the transition layer 3 closest to the inner core 1 is equal to or greater than the L-lactic acid monomer content in the raw material components used for the polylactic acid fiber tow of the transition layer 3 closest to the outer skin 2.

[0042] Each of the multiple transition layers 3 is processed in a group, and various raw materials are processed on multiple production lines to form polylactic acid fiber tow, and finally each layer can be coated based on the relationship of L-lactic acid monomer content.

[0043] Furthermore, a nucleating agent is also added to the raw material components used for the polylactic acid fiber tow of the transition layer 3. The amount of nucleating agent in these raw material components is less than or equal to the amount of nucleating agent in the first raw material component, and greater than or equal to the amount of nucleating agent in the second raw material component. In the case of multiple transition layers, the amount of nucleating agent added to the raw material components used for the polylactic acid fiber tow of the transition layer 3 increases as you move closer to the inside.

[0044] Finally, an acetate fiber tow layer is placed on the outside of the outer skin 2, that is, the outside of the polylactic acid fiber tow filter rod is covered with an acetate fiber tow outer layer. By utilizing the adhesive effect and adsorption performance of the acetate fiber tow layer, the stability of the filter rod structure is further improved and the adsorption performance of the filter rod is ensured.

[0045] Example 3: As shown in Figure 2, the present invention relates to a method for manufacturing polylactic acid fiber filter rods processed in the group of all the above examples, S1: A step of obtaining polylactic acid having a first predetermined content of L-racemic mixture, adding a dispersant to obtain a first component raw material, inducing crystallization by draft stress during spinning of the first component raw material to obtain a first polylactic acid fiber tow, The steps include obtaining polylactic acid having a second predetermined value lower than the first predetermined value for S2:L-racemic content, adding glycerol triacetic acid to obtain a second component raw material, and spinning the second component raw material into a second polylactic acid fiber tow, The present invention further provides a manufacturing method comprising the steps of: S3: forming an inner core by compounding a plurality of first polylactic acid fiber tows; forming an outer skin by compounding a plurality of second polylactic acid fiber tows; and covering the outside of the inner core with the outer skin to form a polylactic acid fiber filter rod having a skin core structure.

[0046] Before performing step S3, obtain polylactic acid having a third predetermined L-racemic content, obtain a third polylactic acid fiber tow, and combine multiple third polylactic acid fiber tows to form a transition layer. When step S3 is executed, the transition layer covers the outside of the inner core, and the outer skin further covers the outside of the transition layer.

[0047] After step S3 is performed, the outside of the outer layer skin is covered with an acetate fiber tow layer.

[0048] The polylactic acid fiber filter rods and their manufacturing methods processed by the group according to the present invention are easy to install, and by strictly controlling the properties of the polylactic acid raw material, all outer layer skins have a uniform degree of crystallinity, all inner layer cores also have a uniform degree of crystallinity, and when the tow crystallizes, the nodes are uniformly distributed, and the inside and outside of the manufactured polylactic acid fiber filter rod have a gradually changing degree of crystallinity, the processing process is more stable, and the adsorption performance of the filter rod is ensured.

[0049] The present invention is not limited to the specific embodiments described above, and various modifications and changes are possible. Any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical substance of the present invention should all be included within the scope of the claims of the present invention.

Claims

1. A method for manufacturing a polylactic acid fiber filter rod processed in a group, S1: A step of obtaining polylactic acid having a first predetermined L-racemic content, adding a dispersant to obtain a first component raw material, inducing crystallization by draft stress during spinning of the first component raw material to obtain a first polylactic acid fiber tow, S2: A step of obtaining polylactic acid having a second predetermined value lower than the first predetermined value, adding glycerol triacetic acid to obtain a second component raw material, and spinning the second component raw material into a second polylactic acid fiber tow, A manufacturing method characterized by comprising the steps of: S3: forming an inner core by compounding a plurality of first polylactic acid fiber tows; forming an outer skin by compounding a plurality of second polylactic acid fiber tows; and covering the outside of the inner core with the outer skin to form a polylactic acid fiber filter rod having a skin core structure.

2. Before performing step S3, obtain polylactic acid having a third predetermined L-racemic content, obtain a third polylactic acid fiber tow, and combine multiple third polylactic acid fiber tows to form a transition layer. A method for manufacturing a polylactic acid fiber filter rod processed by the group according to claim 1, characterized in that when step S3 is performed, the outside of the inner core is covered with the transition layer, and the outside of the transition layer is further covered with the outer skin.

3. A method for producing a polylactic acid fiber filter rod processed in the group according to claim 1, characterized in that, after performing step S3, the outside of the outer layer skin is covered with an acetate fiber tow layer.

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