Treatment methods for textile fibers of different lengths
By separating recycled textile fibers through grading and refining steps in a liquid medium, the problem of long fibers interfering with sizing processing is solved, and the effective separation and uniform distribution of short fibers are achieved, improving fiber separation efficiency and processing convenience.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- VALMET TECH OY
- Filing Date
- 2022-11-24
- Publication Date
- 2026-05-26
AI Technical Summary
Long fibers in recycled textile fiber sizing interfere with further processing of the sizing and make it difficult to separate synthetic fibers from natural fibers.
Fibers are classified in a liquid medium at a predetermined concentration using specific types of sieves and flotation steps, including slotted or perforated sieves, to separate short and long fibers and refine the long fibers into short fibers.
It achieves effective separation of short fibers, ensures uniform fiber length distribution, facilitates further processing, reduces energy consumption, and improves fiber separation efficiency.
Smart Images
Figure CN118076778B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for processing textile fibers of different lengths. Background of the Invention
[0003] Recycled textile fibers typically have a wide length distribution. The sizing agent for recycled textile fibers comprises fibers of varying lengths and from different raw materials. Long fibers in the sizing agent interfere with further processing. Furthermore, it is difficult to separate synthetic fibers from the sizing agent.
[0004] Invention Summary
[0005] One object of the present invention is to provide a method for overcoming the aforementioned problems. This object is achieved by a method comprising classifying fibers in a liquid medium at predetermined concentrations according to fiber length. Preferred embodiments of the invention include, but are not limited to, classifying within a specific concentration range, using a specific type of sieve basket, and including a flotation step.
[0006] The term "short fiber" is used in this document. Short fiber refers to fibers whose length is determined to belong to a short fiber fraction. The fiber length in a short fiber fraction can vary depending on the intended end use. Furthermore, more than one short fiber fraction may exist, each with its own fiber length distribution. Short fiber fractions can be used for the same or different end uses. The short fiber fraction may alternatively be referred to as the first good pulp (accept).
[0007] The average fiber length of the short fiber fraction can be 30% to 80% of the initial average fiber length of the feed, preferably 40% to 70%, and more preferably 50% to 60%.
[0008] The term "long fiber" is used in this article. Long fibers refer to fibers whose length is determined to belong to the long fiber fraction, and which are longer than short fibers. Furthermore, there may be more than one long fiber fraction, each with its own fiber length distribution. The long fiber fraction may alternatively be referred to as the second good pulp.
[0009] The term "refine" or "refining" is used in this article. This term refers to cutting fibers or fiberizing their surface in order to obtain shorter fibers.
[0010] The term "flotation" is used in this article. This term refers to a method used to separate certain fibers from each other, that is, to separate short fibers from long fibers, or to separate man-made fibers, such as synthetic fibers, from natural fibers.
[0011] The term "dispersion" is used in this article. When fibers are dispersed, it means that they are spread out in a liquid medium. In addition, any clumps that may be present may disperse.
[0012] The average fiber length of the long fiber fraction can be higher than 105% of the initial average fiber length of the feed, preferably higher than 110%, and more preferably higher than 120%.
[0013] The fiber lengths of the feed, short fiber, and long fiber fractions can be analyzed and measured using the Valmet FS5 fiber analyzer or other similar equipment. The Valmet FS5 fiber analyzer is based on optical measurement, meaning the device scans the fiber material and uses a specific algorithm to calculate the fiber length.
[0014] This invention is based on the idea of using short fibers obtained from recycled textile sizing to manufacture high-quality new products.
[0015] The advantages of this method are its ability to effectively separate short fiber fractions and achieve the desired fiber length with low energy consumption. It also allows for the attainment of a desired fiber length distribution. In addition to these advantages, the uniform propagation of the fiber mass during the process ensures smooth operation for further processing steps, such as flotation. The uniform fiber length distribution of the fiber mass makes it easier to separate fibers into specific fractions.
[0016] The primary objective behind this method is to recover short fibers from recycled textile fiber slurry by classifying it into at least two fractions. The fractions containing long fibers are refined into short fibers to obtain short fibers for further processing. Furthermore, only those fractions that require refining are processed.
[0017] Recycled textile fiber sizing may include post-industrial waste, such as leftover fabric or clothing scraps, as well as other textiles returned from retailer inventory, or post-consumer textile waste. The main component may be recyclable clothing discarded by people. The raw materials in the recycled textile fiber sizing may be shredded and then processed using the methods of this invention.
[0018] Regenerated textile fibers can include fibers of different lengths and from different raw materials, but exclude natural wood fibers, such as mechanical pulp. Regenerated textile fibers can include natural fibers and / or man-made fibers. Natural fibers include, for example, cotton, flax, hemp, wool, and silk. Man-made fibers can include regenerated fibers and / or synthetic fibers. Regenerated fibers include, for example, viscose and acetate fibers. Synthetic fibers include, for example, polyester, polyamide, and elastane.
[0019] Regenerated textile fibers can include staple fibers and / or filaments. The length of recycled textile fibers may differ from their original length because they are shredded to form the recycled textile fiber sizing. The original length of cotton fibers can be 25 mm to 45 mm. The original length of man-made staple fibers in yarn can be 20 mm to 60 mm. Filaments are continuous, meaning their length is unlimited. For example, fibers that were originally continuous filaments can be fibers of a certain length in the recycled fiber sizing. However, the long fibers contained in the recycled textile fiber sizing can create difficulties for further processing.
[0020] Short fiber fractions can be used to manufacture, for example, nonwoven fabrics or dry-formed paper. Recycled short fiber fractions can be used in conjunction with virgin fibers. Furthermore, short fiber fractions can be used to manufacture dissolving pulp.
[0021] Long fiber fractions can be used in yarn. Recycled long fiber fractions can be used with virgin fibers.
[0022] In addition to the applications of short fiber grading described above, this method can also be used to form slurries with a desired fiber length distribution. This method can be used to grade natural fibers, such as cotton, to obtain the desired fiber length distribution. This material can be used as microfibrillated cellulose (MFC).
[0023] A method for grading textile fibers of different lengths involves grading the fibers in a liquid medium at a predetermined concentration. Concentration refers to the dry solids content of the sizing agent in the liquid medium, i.e., the presence of a suspension composed of the sizing agent and the liquid medium. Typically, the main component of the liquid medium is water. The predetermined grading concentration may range from 0.2% to 4.0%, preferably from 0.5% to 2.0%, and more preferably from 0.8% to 1.2%. The concentration is defined as C = 100x / (x + y), where C is the concentration expressed as a percentage, x is the mass of the sizing agent, and y is the mass of the residue in the suspension.
[0024] The method involves grading fibers into at least two fractions based on fiber length in a liquid medium. The fibers are sorted into at least short and long fibers, i.e., into two fractions, which may be referred to as the first and second good pulp, but the fibers may also be sorted into more fractions, each with its own fiber length distribution. It is important that the fibers are graded first, because some fibers are very short and do not require any further processing regarding fiber length.
[0025] Fibers are sorted into different grades using slotted or perforated screen baskets. Slotted screen baskets can have a slot width of 0.1 to 0.5 mm. Perforated screen baskets can have an aperture diameter of 0.1 to 3.0 mm.
[0026] The method involves guiding at least one fraction containing long fibers to a refining step. The long fibers are refined into short fibers in a refining machine. The refining machine can be an LC refining machine (low concentration 3.5% to 5%) or an HC refining machine (high concentration 25% to 40%).
[0027] This method involves classifying refined fibers. The refined fibers are sorted into at least two fractions, each with its own fiber length distribution. Long fibers may be repeatedly cycled through the refining and classification steps until the desired result is achieved. Fiber lengths in each fraction can be measured, and classification operating parameters, such as flow ratio, feed concentration, and / or rotation speed, can be adjusted as needed. Based on adjustments to the operating parameters, the fiber distribution of both short and long fiber fractions can be affected.
[0028] Brief description of the attached figures
[0029] The invention will now be described in more detail with reference to the accompanying drawings and preferred embodiments, wherein...
[0030] Figure 1 A flowchart of the method is shown;
[0031] Figure 2 The fiber distribution of one experiment is shown. Invention Details
[0033] Figure 1 A flowchart of a method for grading textile fibers of different lengths is shown. In stage 1, recycled textile sizing can be dispersed in water to a concentration between 0.2% and 4%. The fibers can then proceed to a refining or grading step. Alternatively, the recycled textile fiber sizing can be fed directly to the refining step.
[0034] In stage 2, the recycled textile fiber slurry is sent to a classification stage, where the fibers of the slurry are classified into at least two fractions. In stage 3, the fraction containing short fibers, i.e., the first good slurry, can be directed to further processing. Further processing steps may be, for example, flotation, to separate the remaining synthetic fibers from the fraction of interest. The short fiber fraction may have fibers less than two millimeters in length. However, if more than two fractions are present, more than one fraction may be directed to further processing.
[0035] In stage 4, the fraction with long fibers, i.e., the second good pulp, is guided to the refining stage. The long fiber fraction may have fibers with a length of at least two millimeters. The long fibers are shortened by refining. After the refining step, the fibers are returned to the grading step at a concentration of 0.2% to 4%. The long fibers can be repeatedly cycled through the refining and grading steps as needed until the desired fiber length is obtained.
[0036] Example
[0037] Table 1 shows the fiber distribution of the feedstock (i.e., recycled textile fiber slurry), which is fed into a grading process to produce short fiber fractions and long fiber fractions. Table 1 also shows the fiber distribution of the short fiber fraction and the fiber distribution of the long fiber fraction.
[0038] Table 1
[0039]
[0040] The fiber lengths of the feed, short fiber, and long fiber fractions can be analyzed and measured using a Valmet FS5 fiber analyzer or other similar equipment. Fractions with a fiber length of 3.20 or greater contain the longest fibers; that is, the fraction may contain textile fibers whose length corresponds to the original length of the textile fibers mentioned earlier herein. In this embodiment, the feed is derived from recycled clothing fibers, including cotton and synthetic fibers.
[0041] Figure 2 The results in Table 1 are illustrated graphically. It can be clearly seen that the recycled textile fiber sizing can be effectively sorted into short fiber fractions and long fiber fractions. In other words, compared to the initial feed, i.e., the recycled textile fiber sizing, the short fiber fraction has a higher proportion of shorter fibers, and the long fiber fraction has a higher proportion of longer fibers. Table 1 shows that the short fiber fraction contains only a very small amount of fibers longer than 3.20 mm.
[0042] Synthetic materials can also be effectively separated from the short fiber fraction. Note that the recycled textile fiber slurry initially contained 8.0% by weight of synthetic fibers. After grading and refining processes, the short fiber fraction contained 2.6% by weight of synthetic fibers, and the long fiber fraction contained 10.3% by weight of synthetic fibers.
[0043] It will be apparent to those skilled in the art that the inventive concept of this application can be implemented in various ways with advancements in technology. The invention and its embodiments are not limited to the above-described embodiments and may vary within the scope of the claims.
Claims
1. A method for processing textile fibers of different lengths, said textile fibers comprising natural fibers and man-made fibers, said man-made fibers comprising synthetic fibers, characterized in that, The method includes: - In a liquid medium with a concentration of 0.2% to 4%, the fibers are graded into at least two fractions according to fiber length, said two fractions being a first good pulp and a second good pulp. - A second pulp is guided to a refining step in a liquid medium, wherein the fibers of the second pulp are longer than those of the first pulp; and - The refined fibers are graded into at least two grades according to fiber length in a liquid medium with a concentration of 0.2% to 4%.
2. The method according to claim 1, characterized in that, The textile fibers are graded in a liquid medium with a concentration of 0.5% to 2%.
3. The method according to claim 1 or 2, characterized in that, The textile fibers are graded in a liquid medium with a concentration of 0.8% to 1.2%.
4. The method according to claim 1 or 2, characterized in that, The method includes grading using slotted or perforated sieve baskets.
5. The method according to claim 3, characterized in that, The method includes grading using slotted or perforated sieve baskets.
6. The method according to claim 1 or 2, characterized in that, The method includes guiding the first good pulp to further processing.
7. The method according to claim 3, characterized in that, The method includes guiding the first good pulp to further processing.
8. The method according to claim 4, characterized in that, The method includes guiding the first good pulp to further processing.
9. The method according to claim 5, characterized in that, The method includes guiding the first good pulp to further processing.
10. The method according to claim 6, characterized in that, The method includes a flotation step for separating synthetic fibers.
11. The method according to any one of claims 7 to 9, characterized in that, The method includes a flotation step for separating synthetic fibers.
12. The method according to claim 1 or 2, characterized in that, The textile fibers are derived from recycled textile fiber slurry.
13. The method according to claim 3, characterized in that, The textile fibers are derived from recycled textile fiber slurry.
14. The method according to claim 4, characterized in that, The textile fibers are derived from recycled textile fiber slurry.
15. The method according to claim 5, characterized in that, The textile fibers are derived from recycled textile fiber slurry.
16. The method according to claim 6, characterized in that, The textile fibers are derived from recycled textile fiber slurry.
17. The method according to any one of claims 7 to 10, characterized in that, The textile fibers are derived from recycled textile fiber slurry.
18. The method according to claim 11, characterized in that, The textile fibers are derived from recycled textile fiber slurry.
19. The method according to claim 1 or 2, characterized in that, Prior to the grading step, the method includes dispersing the fibers in a liquid medium.
20. The method according to claim 3, characterized in that, Prior to the grading step, the method includes dispersing the fibers in a liquid medium.
21. The method according to claim 4, characterized in that, Prior to the grading step, the method includes dispersing the fibers in a liquid medium.
22. The method according to claim 5, characterized in that, Prior to the grading step, the method includes dispersing the fibers in a liquid medium.
23. The method according to claim 6, characterized in that, Prior to the grading step, the method includes dispersing the fibers in a liquid medium.
24. The method according to any one of claims 7 to 10, characterized in that, Prior to the grading step, the method includes dispersing the fibers in a liquid medium.
25. The method according to claim 11, characterized in that, Prior to the grading step, the method includes dispersing the fibers in a liquid medium.
26. The method according to claim 12, characterized in that, Prior to the grading step, the method includes dispersing the fibers in a liquid medium.
27. The method according to any one of claims 13 to 16, characterized in that, Prior to the grading step, the method includes dispersing the fibers in a liquid medium.
28. The method according to claim 17, characterized in that, Prior to the grading step, the method includes dispersing the fibers in a liquid medium.
29. The method according to claim 18, characterized in that, Prior to the grading step, the method includes dispersing the fibers in a liquid medium.
30. The method according to claim 1 or 2, characterized in that, Before any refining step, it is graded into first and second good pulp.
31. The method according to claim 3, characterized in that, Before any refining step, it is graded into first and second good pulp.
32. The method according to claim 4, characterized in that, Before any refining step, it is graded into first and second good pulp.
33. The method according to claim 5, characterized in that, Before any refining step, it is graded into first and second good pulp.
34. The method according to claim 6, characterized in that, Before any refining step, it is graded into first and second good pulp.
35. The method according to any one of claims 7 to 10, characterized in that, Before any refining step, it is graded into first and second good pulp.
36. The method according to claim 11, characterized in that, Before any refining step, it is graded into first and second good pulp.
37. The method according to claim 12, characterized in that, Before any refining step, it is graded into first and second good pulp.
38. The method according to any one of claims 13 to 16, characterized in that, Before any refining step, it is graded into first and second good pulp.
39. The method according to claim 17, characterized in that, Before any refining step, it is graded into first and second good pulp.
40. The method according to claim 18, characterized in that, Before any refining step, it is graded into first and second good pulp.