A paper-plastic composite fiber and its preparation method and application, and pulp molded product

Abstract

The present invention discloses a paper-plastic composite fiber, a preparation method and application thereof, and a pulp molded product. The preparation method of the paper-plastic composite fiber comprises the following steps: S1, crushing: crushing the paper-plastic composite material into fragments; S2, fiberizing: fiberizing the fragments of step S1 with a fiberizing device to obtain a cotton-like material; S3, screening: screening the cotton-like material obtained in step S2 through a screen, and the screened fibers are the paper-plastic composite fibers. The present invention not only prepares a biodegradable paper-plastic composite fiber that can be used in pulp molding, but also the fiber prepared by the present invention can effectively solve the problem of dispersion of synthetic fibers in pulp during pulp molding, thereby greatly improving the strength of pulp molded products and reducing powder and hair loss defects.

Description

Technical Field

[0001] The invention belongs to the field of resource recycling and reuse, and particularly relates to a paper-plastic composite fiber and a preparation method and application thereof, and a pulp molded product. Background Art

[0002] Among the four pillars of modern packaging - paper, plastic, metal and glass materials, glass is fragile, metal packaging has a large total mass and is not easy to carry, etc. Plastic packaging materials occupy an important proportion of packaging materials due to their excellent performance and low price. However, in recent decades, with the improvement of living standards and the popularization of environmental protection concepts, the disadvantages of plastic packaging products have become increasingly prominent. They are discarded at will after use and are difficult to degrade in the natural environment, causing great pollution to the environment. It is a general trend for traditional non-biodegradable plastic products to be replaced by environmentally friendly packaging materials, and pulp molding packaging materials with good environmental characteristics have come into being.

[0003] Pulp molding is a three-dimensional papermaking technology. It uses waste paper, bamboo pulp, sugarcane pulp, wood pulp and other plant fibers as raw materials. A special mold is used on a molding machine to shape a paper product of a certain shape. Specifically, pulp molded products are made of waste paper, bamboo pulp, sugarcane pulp, wood pulp and other plant primary fibers or secondary fibers. According to performance requirements, a variety of chemical additives are mixed to form a certain concentration of pulp suspension. A wet paper mold is formed by a special mold forming machine. After demolding, dehydration and drying, a paper product with a specific geometric cavity structure and certain buffering performance is formed through a finishing process. Pulp molding packaging materials have become the best alternative to disposable plastic products due to their wide range of raw materials, excellent packaging material application performance, simple production and processing, easy molding, renewable and easy recycling and biodegradability. In the Life Cycle Assessment (LCA), it is recognized as the most promising green sustainable packaging material. In recent years, related application research and development have been the fastest. Pulp molded products can be completely degraded after use and have many advantages such as renewable resources, recyclable and environmental protection. However, compared with plastic packaging materials, the strength and surface properties are still insufficient, such as low hardness, insufficient stiffness, low surface strength, easy to fall off powder and chips, etc. How to improve the strength performance of pulp molded products without affecting the green and environmentally friendly characteristics of pulp molded products is an urgent problem to be solved.

[0004] There are many methods for strengthening pulp molded products in the prior art, such as using better raw materials, modifying the raw materials (such as acid treatment, bio-enzyme treatment), or adding suitable reinforcing materials (such as using pure PLA fibers as reinforcing materials), but the effects are different, and almost all of them have defects such as low strength, powder and chipping. Among these prior arts, the best strengthening effect is to use pure PLA fibers as reinforcing materials, such as the "A method for strengthening pulp molded products by adding PLA" disclosed in CN109137599A, but the PLA fibers in the invention are single-component fiber structures, and the manufacturing process is complicated and the cost is relatively high. In particular, during the pulping process, paper fiber is a hydrophilic material with strong hygroscopicity and a density of 0.5-0.9g / cm 3 , suspended in water, while single-organized PLA fiber is a hydrophobic material that does not absorb water and has a density of 1.25g / cm 3 It is easy to settle in water, which causes the PLA fiber and paper fiber to separate easily. It is not easy to disperse evenly in the pulp, resulting in the products produced to lose powder and hair easily and uneven performance (strength). In actual production, PLA fiber is also difficult to be directly used in pulp molding process. Summary of the invention

[0005] In order to make up for the deficiencies of the prior art, the present invention provides a paper-plastic composite fiber and a preparation method and application thereof, and a pulp molded product.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a paper-plastic composite fiber, comprising the following steps:

[0008] S1. Crushing: crushing the paper-plastic composite material into pieces;

[0009] S2, fiberization: fiberizing the fragments in step S1 using a fiberizing device to obtain a cotton-like material;

[0010] S3, screening: the cotton-like material obtained in step S2 is screened through a sieve, and the screened fibers are the paper-plastic composite fibers.

[0011] Preferably, the paper-plastic composite material in step S1 refers to laminated paper or coated paper, which contains 10-40 wt % of resin.

[0012] Preferably, the resin is at least one of PLA, PHA, PBS, PBAT, PCL, and PPC.

[0013] Preferably, the paper-plastic composite material in step S1 is PLA coated paper.

[0014] Preferably, the size of the fragments after crushing in step S1 is controlled to be less than 12 mm.

[0015] Preferably, in step S2, the fiber-forming equipment is a plastic grinder or a wood crusher, and the operating temperature is controlled below 45°C.

[0016] Preferably, in step S3, a sieve with a mesh size of 10 or larger is used for screening.

[0017] In a second aspect, the present invention provides a paper-plastic composite fiber, which is prepared by the method described in the first aspect.

[0018] In a third aspect, the present invention further provides a use of the paper-plastic composite fiber described in the second aspect in pulp molding, wherein the paper-plastic composite fiber is used as a reinforcing agent in the pulp molding process.

[0019] In a fourth aspect, the present invention further provides a pulp molded product, which is produced by using the paper-plastic composite fiber described in the second aspect as a reinforcing agent and plant fibers through a pulp molding process.

[0020] The beneficial effects of the present invention include:

[0021] The present invention not only prepares a biodegradable paper-plastic composite fiber that can be used in pulp molding, but also the fiber prepared by the invention can effectively solve the problem of dispersion of synthetic fibers in pulp during pulp molding, thereby greatly improving the strength of pulp molded products and reducing powder and hair loss defects.

[0022] Specifically, it has the following advantages:

[0023] 1. The present invention prepares a paper-plastic composite fiber by simple processing means, and the paper and the polymer are evenly pasted together by a coating or laminating method, and then the paper-plastic composite fibers prepared by the above method are also bonded together. When applied to pulp molding, the paper-plastic composite fiber completely becomes a hygroscopic material, forming a flocculent, which can be suspended in water together with the pulp, and is evenly dispersed in the pulp by stirring, which better solves the problem of phase separation caused by simply adding synthetic fibers and paper fibers, thereby improving the strength of pulp molded products.

[0024] 2. The paper-plastic composite fiber prepared by the present invention is used as a reinforcing agent in pulp molding and can be further plasticized during molding so that the paper fibers can adhere to each other, thereby reducing the phenomenon of powder and hair loss.

[0025] 3. The raw materials of the paper-plastic composite fiber of the present invention are widely available, the preparation method is simple, and the cost is lower.

[0026] 4. The paper-plastic composite fiber of the present invention is completely biodegradable, effectively reducing pollution to the environment. DETAILED DESCRIPTION

[0027] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention. In the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0028] An embodiment of the present invention provides a method for preparing a paper-plastic composite fiber, which comprises the following steps:

[0029] S1. Crushing: crushing the paper-plastic composite material into pieces;

[0030] S2, fiberization: fiberizing the fragments in step S1 using a fiberizing device to obtain a cotton-like material;

[0031] S3, screening: the cotton-like material obtained in step S2 is screened through a sieve, and the screened fibers are the paper-plastic composite fibers.

[0032] When the obtained paper-plastic composite fiber is used as a reinforcing agent in pulp molding, it can be evenly dispersed in the pulp, thereby improving the strength of the pulp molded product and reducing the defects of powder and hair loss.

[0033] In a preferred embodiment, the paper-plastic composite material in step S1 refers to laminated paper or coated paper, which contains 10-40 wt % of resin.

[0034] In a preferred embodiment, the resin is at least one of PLA, PHA, PBS, PBAT, PCL, and PPC.

[0035] In a preferred embodiment, the paper-plastic composite material in step S1 is PLA coated paper.

[0036] In a preferred embodiment, the size of the fragments after the crushing in step S1 is controlled to be less than 12 mm. Experiments have shown that the size of the fragments after the crushing (whether the length or width of the fragments) is controlled to be less than 12 mm, which is more conducive to the fiberization (i.e., grinding) in step S2. If the size exceeds 12 mm, it is easy to agglomerate in the fiberization equipment and is not conducive to grinding.

[0037] In a preferred embodiment, in step S2, the fiber-forming equipment is a plastic grinder or a wood crusher, and the operating temperature is controlled below 45°C to prevent the polymer from agglomerating.

[0038] In a preferred embodiment, in step S3, the screening uses a sieve with a mesh size of 10 or more.

[0039] The specific embodiment of the present invention also provides a paper-plastic composite fiber, which is prepared by the preparation method.

[0040] A specific embodiment of the present invention further provides an application of the paper-plastic composite fiber in pulp molding, wherein the paper-plastic composite fiber is used as a reinforcing agent in the pulp molding process.

[0041] The specific embodiment of the present invention also provides a pulp molded product, which is made by using the paper-plastic composite fiber as a reinforcing agent and plant fiber (such as waste paper, bamboo pulp, sugarcane pulp, wood pulp and other plant primary fibers or secondary fibers) through a pulp molding process.

[0042] The present invention is further described below through examples and comparative examples.

[0043] Example 1

[0044] The preparation method of the paper-plastic composite fiber comprises the following steps:

[0045] S1. Crushing: Crushing the paper-plastic composite material (PLA coated paper with a PLA content of 15 wt%) into pieces using a plastic crusher with a sieve hole of less than or equal to 12 mm;

[0046] S2, fiber formation: the fragments from step S1 are put into a plastic grinding machine for reciprocating grinding, and the equipment is cooled by cooling water to ensure that the operating temperature of the equipment does not exceed 45° C. to prevent the PLA from heating up and agglomerating, thereby obtaining a cotton-like material;

[0047] S3, screening: the cotton-like material obtained in step S2 is screened through a vibrating screen with a mesh size of 10 meshes, and the screened fibers are the paper-plastic composite fibers of Example 1.

[0048] Example 2

[0049] The difference from Example 1 is that step S3 uses a vibrating screen with a mesh size of 20 for screening, and the rest of the method is the same.

[0050] Example 3

[0051] The difference from Example 1 is that step S3 uses a vibrating screen with a mesh size of 30 meshes for screening, and the rest of the method is the same.

[0052] Example 4

[0053] The difference from Example 1 is that step S3 uses a vibrating screen with a mesh size of 60 mesh for screening, and the rest of the method is the same.

[0054] The paper-plastic composite fibers of Examples 1-4 were mixed with sugarcane pulp to make pulp (in the pulp, the content of the paper-plastic composite fibers was 10wt%, and the content of sugarcane paper was 90wt%). Test samples were made through a pulp molding process and performance tests were performed. The test results are shown in Table 1.

[0055] Comparative Example 1

[0056] 100% sugarcane pulp was used to make test samples through pulp molding process, and performance tests were performed. The test results are shown in Table 1.

[0057] Comparative Example 2

[0058] 1.5D, 3mm PLA fiber was selected as a reinforcing agent and mixed with sugarcane pulp to make pulp (in the pulp, the content of PLA fiber was 10wt%, and the content of sugarcane paper was 90wt%). Test samples were made through pulp molding process and performance tests were performed. The test results are shown in Table 1.

[0059] Table 1 Properties of paper-plastic composite fibers with different fineness added to sugarcane paper

[0060]

[0061] In Table 1, the tensile strength was tested using the GB / T 1040 method, the flexural strength was tested using the GB / T 9341 method, and the powder loss and hair loss rate were tested as follows: a 25mm*25mm test specimen was applied with a 500g weight, and rubbed back and forth 30 times on an 80-mesh corundum emery cloth at a distance of 50mm to determine the powder loss and hair loss weight loss rate of the sample.

[0062] By comparing with the above embodiments, it can be found that the paper-plastic composite fibers in the embodiments of the present invention are added to pulp molded products, which improves the strength of the pulp molded products to varying degrees and reduces the powder and hair loss phenomena.

[0063] The material of Example 2 of the present invention was mixed with sugarcane paper at a ratio of 5wt%, 10wt%, 15wt% and 20wt% in the pulp to make pulp, and test samples were made through pulp molding process. Performance tests were performed. The test results are shown in Table 2. The test method is the same as above.

[0064] Table 2 Performance of different proportions of sugarcane pulp added to paper-plastic composite fiber of Example 2 of the present invention

[0065]

[0066] It can be seen from Table 2 that, when the paper-plastic composite fiber of Example 2 is used in different proportions, the various properties of the pulp molded products are significantly improved compared with those without the addition of the paper-plastic composite fiber of the present invention. When 10wt% is added, the strength reaches the maximum value, and when the content reaches 15wt%, the powder and hair loss rate reaches the minimum value.

[0067] Weigh 10 grams each of the paper-plastic composite fibers of Examples 1-4 and the PLA fibers of Comparative Example 2 (hereinafter referred to as samples), mix them with sugarcane paper at a mass ratio of 1:1, put them into a 2L pulper, add 500 ml of water, stir for 2 minutes to make a pulp liquid, and then pour it into a 1L beaker. After standing for 10 minutes, observe whether the sample settles in the water to characterize the dispersibility of the sample. The results are shown in Table 3 below.

[0068] Table 3: Dispersibility of paper-plastic composite fibers and PLA fibers with different fineness added to sugarcane paper

[0069] Test items Example 1 Example 2 Example 3 Example 4 Comparative Example 2 Dispersibility No settlement No settlement No settlement No settlement Obvious settlement

[0070] Through the above test, it is found that no sedimentation phenomenon is observed in the four embodiments of the present invention, while in Comparative Example 2, fiber stratification can be clearly observed after standing for 10 minutes, and most of the PLA fibers will settle to the bottom of the beaker, so that the dispersibility of the paper-plastic composite fiber of the present invention is better than that of the pure PLA fiber of Comparative Example 2.

[0071] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the absence of mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A method for preparing paper-plastic composite fiber, characterized in that: The steps include: S1. Crushing: Crushing the paper-plastic composite material into fragments, wherein the paper-plastic composite material refers to coated paper or film-coated paper, containing 10-40wt% of resin, and the size of the fragments after crushing is controlled to be less than 12mm; S2, fiberization: the fragments of step S1 are fiberized by a fiberizing device to obtain a cotton-like material, wherein the fiberizing device is a plastic mill or a wood crusher, and the operating temperature is controlled below 45°C; S3, screening: the cotton-like material obtained in step S2 is screened through a sieve with a mesh size of 10 or more, and the screened fibers are the paper-plastic composite fibers; the paper-plastic composite fibers are used as a reinforcing agent in pulp molding. When applied to pulp molding, the paper-plastic composite fibers completely become a hygroscopic material, forming a flocculent, which can be suspended in water together with the pulp and evenly dispersed in the pulp by stirring.

2. The method for preparing the paper-plastic composite fiber according to claim 1, characterized in that: The resin is at least one of PLA, PHA, PBS, PBAT, PCL, and PPC.

3. The method for preparing the paper-plastic composite fiber according to claim 1, characterized in that: The paper-plastic composite material in step S1 is PLA coated paper.

4. A paper-plastic composite fiber, characterized in that: Prepared by the preparation method according to any one of claims 1 to 3.

5. Use of the paper-plastic composite fiber according to claim 4 in pulp molding, characterized in that: The paper-plastic composite fiber is used as a reinforcing agent in the pulp molding process.

6. A pulp molded product, characterized in that: The paper-plastic composite fiber according to claim 4 is used as a reinforcing agent and plant fibers are prepared by a pulp molding process.

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