Fiber molding composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of degradable materials, in particular to a fiber molding composite material and a preparation method and application thereof. The fiber molding composite material comprises a biological primary membrane and plant fibers, the biological primary membrane and the plant fibers are combined through physical interlocking, and the biological primary membrane comprises a plant primary waterproof covering membrane. According to the chemical-additive-free fiber molding composite material based on the natural plant protogenetic membrane, plant protogenetic membranes such as a bamboo cavity inner wall protogenetic membrane or fusu and the like are used as film covering materials, traditional plastic or chemical modified bio-based membrane materials can be replaced, and meanwhile the chemical-additive-free waterproof function is achieved.

Description

Technical Field

[0001] This invention relates to the field of biodegradable materials technology, and in particular to a fiber-molded composite material, its preparation method, and its application. Background Technology

[0002] The surge in demand for plastic alternatives has driven rapid growth in the biodegradable materials market. However, current mainstream alternatives such as polylactic acid (PLA) and starch-based materials have significant drawbacks. PLA requires stringent degradation conditions, with a degradation rate of less than 10% in natural environments; starch-based materials have high water absorption and poor mechanical strength, necessitating the addition of chemical plasticizers to improve their performance.

[0003] Fiber molding, using plant fibers such as bagasse, bamboo pulp, and wood pulp as raw materials, has become a mainstream alternative for food packaging and tableware due to its biodegradability and renewable raw materials. However, virgin fiber molded products are highly hydrophilic, requiring surface treatment to achieve waterproof and oil-repellent properties, and current technologies struggle to balance environmental friendliness and functionality. Existing waterproof and oil-repellent treatment technologies for molded products mainly fall into two categories: surface coating and adding waterproof and oil-repellent agents to the pulp. Plastic coating materials are primarily polyethylene (PE) and polypropylene (PP) films, bonded to the pulp matrix via adhesives or hot-pressing. These coatings present challenges such as non-degradability (PE degradation takes over 100 years), difficulty in recycling (high cost of separating the coating from the pulp), and food safety risks (adhesives may contain bisphenol A and other migrating substances). Chemical coatings, such as fluorinated compounds, paraffin emulsions, and acrylic resins, are also used to achieve waterproofing. However, fluorides exhibit bioaccumulative toxicity, paraffin coatings have poor temperature resistance (melting above 60℃), and emulsifiers are required to reduce surface tension. Some studies have shown that starch films can be wet-laminated or hot-pressed, but chemical crosslinking agents (such as glutaraldehyde) need to be added to enhance water resistance, which leads to excessive total migration.

[0004] However, existing coating technologies rely on non-degradable materials (PE / PP) or pseudo-environmentally friendly materials (PLA / starch-based): PE / PP plastic coatings provide waterproofing and oil resistance, but are non-degradable, difficult to recycle, and pose food safety risks; PLA / PHA-based biopolymer coatings, while touted as "degradable," contain hidden non-environmentally friendly factors, such as the difficulty in PLA degradation (industrial composting requires harsh conditions, and it hardly degrades in the natural environment), the release of microplastics, and the addition of chemical additives leading to excessive total migration; chemical coatings such as fluorides and paraffin emulsions have bioaccumulative toxicity, and paraffin emulsions have poor temperature resistance, requiring the addition of emulsifiers and other chemical additives, resulting in insufficient environmental friendliness and safety. Existing fluorinated waterproofing agents are effective, but pose health risks and have a half-life in the environment of up to decades, making them difficult to decompose. Paraffin / mineral oil-based coatings only provide short-term hydrophobic effects, are easily dissolved by oils, and mineral oil components (MOSH / MOAH) can migrate into food, raising safety concerns. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a fiber-molded composite material, its preparation method, and its application. This invention provides a chemical-free fiber-molded composite material based on natural plant membranes. By utilizing native plant membranes such as the inner wall membrane of bamboo or aloe vera as a coating material, it can replace traditional plastics or chemically modified bio-based membranes, while simultaneously achieving a chemical-free waterproof function.

[0006] Firstly, this invention provides a fiber-molded composite material comprising a bio-based membrane and plant fibers; the bio-based membrane and the plant fibers are physically interlocked, and the bio-based membrane includes a plant-based waterproof coating. This invention provides a solution that is environmentally friendly throughout its entire life cycle, free of chemical additives, and combines functionality and safety, overcoming the shortcomings of existing coating and waterproofing technologies. This invention replaces non-degradable / pseudo-environmentally friendly coating materials. Addressing the issues of non-degradability of existing PE / PP plastic coatings and low natural degradation rates of PLA coatings, neither of which can achieve true environmental friendliness, this invention develops a 100% naturally derived, chemically-free plant-based waterproof coating, such as bamboo film and reed film, etc., biomass films. These are achieved through a one-time hot-pressing process between the film and a wet plant fiber preform, resulting in glue-free composite material that is environmentally friendly and degradable, with non-toxic and harmless degradation products. Furthermore, this invention eliminates chemical waterproofing agents, addressing the risks of toxic migration associated with coatings such as fluorides and paraffin, and the reliance on exogenous chemical agents to achieve hydrophobic functionality. This invention utilizes the dense physical structure of plant native membranes to achieve long-lasting impermeability by blocking the migration path of water molecules rather than through chemical hydrophobic modification. Through the synergistic effect of biomass membranes such as bamboo membranes and aloe vera with the fiber structure of the substrate, waterproofing is achieved without adding any chemical reagents, thus eliminating health and ecological risks from the source.

[0007] In this invention, the physical interlocking combination is achieved by thermo-pressing the biological native membrane and plant fibers together.

[0008] Preferably, the biological native membrane includes a bamboo membrane on the inner wall of a bamboo cavity or a reed membrane on the inner wall of a reed stalk cavity.

[0009] Secondly, the present invention provides a method for preparing the above-mentioned fiber-molded composite material, comprising: 1) Extraction of plant protoplasm: The biomass raw material is mechanically peeled off and dried to obtain plant protoplasm.

[0010] 2) Preparation of wet preform: Plant fibers are uniformly dispersed in water to obtain fiber slurry, and the fiber slurry is vacuum filtered and shaped to obtain wet preform.

[0011] 3) Hot pressing composite: The plant native film is pre-placed on the surface of the wet blank and then hot-pressed.

[0012] The present invention provides a method for preparing fiber-molded composite materials based on native plant membranes such as bamboo membranes and reed membranes. The method involves a single-stage coating process. During the wet molding stage of fiber molding, the physical interlocking of the native plant membrane and plant fibers is directly achieved through a hot pressing process, without the need for adhesives or chemical coupling agents.

[0013] Preferably, in step 1), bamboo is used as the biomass raw material, and the inner wall of the bamboo cavity is mechanically peeled off to obtain a bamboo membrane. The bamboo membrane is then dried to obtain a plant-based membrane with a moisture content of 8% to 12%. Alternatively, reed is used as the biomass raw material, and the inner wall of the reed stalk cavity is mechanically peeled off to obtain a reed membrane. The reed membrane is then dried to obtain a plant-based membrane with a moisture content of 8% to 12%, for example, moisture contents of 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, etc. This invention obtains a plant-based waterproof membrane through mechanical peeling, and by controlling its moisture content, cracking can be effectively prevented, facilitating subsequent processing.

[0014] Further preferred, in step 1), the bamboo membrane is taken from the inner wall of the bamboo cavity of 2-3 year old bamboo; the reed membrane is taken from the inner wall of the reed stalk cavity.

[0015] Further preferred, in step 2), the fiber pulp is selected from one or more mixed pulps selected from pure bamboo pulp, pure wood pulp, pure straw pulp and pure bagasse pulp.

[0016] Further preferred, in step 2), the freeness is 5~45°SR, for example, freeness of 5°SR, 10°SR, 15°SR, 20°SR, 25°SR, 30°SR, 35°SR, 45°SR, etc. The pulp concentration is 3%~90%.

[0017] Further preferred, in step 3), the hot-pressing temperature is 80~250 ℃, for example 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 150 ℃, 180 ℃, 220 ℃, 250 ℃, etc. The hot-pressing time is 15~600 s, and the hot-pressing vacuum negative pressure is -0.08~-0.098 MPa.

[0018] Further preferred, in step 3), the hot pressing temperature is 120~210 ℃, the hot pressing time is 60~300 s, and the hot pressing vacuum negative pressure is -0.09~-0.095 MPa.

[0019] In this invention, by controlling the moisture content of the plant-based membrane, the selection of raw materials, the characteristics of the slurry, and the hot-pressing process parameters, a better physical interlocking bond without chemical additives can be achieved under optimized process conditions, thus optimizing the performance and processing efficiency of the final composite material. Controlling the moisture content of the plant-based membrane (8%~12%) effectively prevents membrane cracking, ensuring smooth processing. During hot pressing, the membrane material and the wet plant fibers form a strong and uniform mechanical bond through physical interlocking without adhesives, imparting waterproof properties to the composite material and completely eliminating the need for chemical waterproofing agents. This process enables rapid and efficient shaping and drying, significantly optimizing production efficiency and energy utilization. The resulting composite material product has a stable structure, good strength, a smooth surface, and excellent waterproofing function, maintaining the material's environmentally friendly nature and ensuring complete biodegradability and environmental safety after use.

[0020] Thirdly, the present invention provides the application of the above-mentioned fiber molding composite material or the fiber molding composite material obtained by the above-mentioned preparation method in the preparation of environmentally friendly, non-toxic, and fully biodegradable materials, including food packaging, trays, children's toys, pet supplies, or disposable tableware.

[0021] The beneficial effects of this invention are at least as follows: 1. Environmentally friendly throughout the entire life cycle: The molding materials covered with native plant membranes such as bamboo membranes and reed membranes have a full degradation rate in the natural environment, and the degradation products are water, CO2 and humus, with no microplastic residues.

[0022] 2. Zero chemical additives: No fluorides, paraffin emulsions, plasticizers or other chemical reagents are added. All components meet food contact safety standards and can directly replace disposable plastic packaging.

[0023] 3. Simplified process: The plant native film and wet embryo are simultaneously hot-pressed, eliminating the need for adhesive lamination or secondary coating steps. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a SEM image of the bamboo fiber molding material with a bamboo film coating provided in Embodiment 1 of the present invention.

[0026] Figure 2 This is a cross-sectional SEM image of the bamboo fiber molding material with a bamboo film coating provided in Embodiment 1 of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0028] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0029] Unless otherwise specified, the techniques or conditions described in the literature of this invention shall apply, or the product instructions shall be followed. Devices, instruments, reagents, etc., whose manufacturers are not specified, are all conventional products that can be purchased through legitimate channels. All experimental reagents and raw materials involved are commercially available products.

[0030] Example 1 This embodiment provides a bamboo membrane-based fiber molding composite material, wherein the bamboo membrane and plant fibers are physically interlocked. The preparation method of the bamboo membrane-based fiber molding composite material includes the following steps: 1) Extraction of plant native membrane: The bamboo material is peeled and dried to obtain the native membrane. The bamboo membrane is taken from the inner wall of the bamboo cavity of 3-year-old bamboo. The plant native membrane is obtained by mechanical peeling and then dried. The moisture content of the membrane after drying is 10%.

[0031] 2) Preparation of fiber molding wet preform: bamboo fiber pulp, beating degree 25°SR, pulp concentration 5%; wet preform is obtained by vacuum filtration molding of fiber pulp.

[0032] 3) Synchronous hot-pressing composite: Pre-placed virgin film (bamboo film) and hot-pressed. Hot-pressing parameters: temperature 120℃, time 300s, vacuum negative pressure -0.092 MPa. Figure 1-2 The images shown are SEM images of the surface and cross-section of the bamboo fiber molding material with bamboo film coating provided in Embodiment 1 of the present invention.

[0033] Example 2 This embodiment provides a fiber-molded composite material based on reed membrane (reed film), wherein reed film and bamboo pulp fiber are physically interlocked. The preparation method of the reed film-based fiber-molded composite material includes the following steps: 1) Extraction of plant protoplasmic membrane: The protoplasmic membrane is obtained by peeling and drying reeds. Reed extract is obtained from the inner wall of the lumbar cavity of mature reed stems, mechanically peeled to obtain the plant protoplasmic membrane, and then dried. The moisture content of the dried membrane is 10%.

[0034] 2) Preparation of fiber molding wet preform: bamboo fiber pulp, beating degree 25°SR, pulp concentration 5%; wet preform is obtained by vacuum filtration molding of fiber pulp.

[0035] 3) Synchronous hot-pressing composite: Pre-placed virgin membrane (reed membrane) and hot-pressed. Hot-pressing parameters: temperature 120℃, time 300s, vacuum negative pressure -0.092 MPa.

[0036] Example 3 This embodiment uses the same method as Embodiment 1, the only difference being that the moisture content of the bamboo membrane in step 1) is adjusted to 3%. The bamboo membrane is brittle and difficult to lay, and micro-cracks appear at the edges of the bamboo membrane during hot pressing.

[0037] Example 4 This embodiment uses the same method as Embodiment 1, the only difference being that the bamboo fiber beating degree in step 2) is adjusted to 60°SR. The bamboo fiber wet preform drains water slowly, prolonging the molding time. During the transfer from the molding mold to the hot pressing mold, it is extremely prone to breakage, tearing, and deformation, increasing the difficulty of operation.

[0038] Example 5 This embodiment uses the same method as Embodiment 1, the only difference being that the hot-pressing temperature in step 3) is adjusted to 50℃. The bamboo membrane and bamboo fiber have weak bonding, resulting in reduced mechanical strength and decreased waterproofing.

[0039] Comparative Example 1 The method is the same as in Example 1, except that a plant-based membrane is not used: 1) Preparation of fiber molding wet blank: bamboo fiber pulp (beating degree 25°SR, same as in Example 1) was vacuum filtered and molded to obtain a wet blank.

[0040] 2) Vacuum hot pressing molding: temperature 120℃, time 300 s, vacuum negative pressure -0.092 MPa.

[0041] Comparative Example 2 The wet preform of this comparative example is the same as that of Comparative Example 1 (bamboo fiber pulp, beating degree 25°SR). The surface is laminated with a polyethylene (PE) film (approximately 20 μm thick).

[0042] Comparative Example 3 The method is the same as in Example 1, except that a plant-based membrane is not used, and a waterproofing agent is applied to the slurry: 1) Preparation of fiber molding wet blank: bamboo fiber pulp (beating degree 25°SR, same as in Example 1), 1.5% perfluoroalkyl compound waterproofing agent is added to the bamboo fiber pulp and mixed and dispersed evenly; wet blank is obtained by vacuum filtration molding of fiber pulp.

[0043] 2) Vacuum hot pressing molding: temperature 120℃, time 300 s, vacuum negative pressure -0.092 MPa.

[0044] The above embodiments and comparative examples were subjected to the following performance tests, and the test results are shown in Table 1.

[0045] Table 1

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fiber-molded composite material, characterized in that, It includes a biological native membrane and plant fibers; the biological native membrane and the plant fibers are physically interlocked together, and the biological native membrane includes a plant native waterproof coating.

2. The fiber-molded composite material according to claim 1, characterized in that, The biological native membrane includes the bamboo membrane on the inner wall of the bamboo cavity or the reed membrane on the inner wall of the reed stalk cavity.

3. The method for preparing the fiber-molded composite material according to claim 1 or 2, characterized in that, include: 1) Extraction of plant protoplasm: The biomass raw material is mechanically peeled off and dried to obtain plant protoplasm; 2) Preparation of wet preform: Plant fiber is pulped to obtain fiber pulp, and the fiber pulp is vacuum filtered and shaped to obtain wet preform; 3) Hot pressing composite: The plant native film is pre-placed on the surface of the wet blank and then hot-pressed.

4. The method for preparing the fiber-molded composite material according to claim 3, characterized in that, In step 1), bamboo is used as a biomass raw material, and the inner wall of the bamboo cavity is mechanically peeled off to obtain a bamboo membrane. The bamboo membrane is then dried to obtain a plant native membrane with a moisture content of 8% to 12%. Alternatively, reed is used as a biomass raw material, and the inner wall of the reed stalk cavity is mechanically peeled off to obtain a reed membrane. The reed membrane is then dried to obtain a plant native membrane with a moisture content of 8% to 12%.

5. The method for preparing the fiber-molded composite material according to claim 4, characterized in that, In step 1), the bamboo membrane is taken from the inner wall of the bamboo cavity of 2-3 year old bamboo; the reed membrane is taken from the inner wall of the reed culm cavity.

6. The method for preparing fiber-molded composite material according to claim 5, characterized in that, In step 2), the fiber pulp is selected from one or more mixed pulps of pure bamboo pulp, pure wood pulp, pure straw pulp and pure bagasse pulp.

7. The method for preparing the fiber-molded composite material according to claim 6, characterized in that, In step 2), the beating degree is 5~45°SR and the pulp concentration is 3%~90%.

8. The method for preparing the fiber-molded composite material according to any one of claims 3-7, characterized in that, In step 3), the hot pressing temperature is 80~250 ℃, the hot pressing time is 15~600 s, and the hot pressing vacuum negative pressure is -0.08~-0.098 MPa.

9. The method for preparing the fiber-molded composite material according to claim 8, characterized in that, In step 3), the hot pressing temperature is 120~210 ℃, the hot pressing time is 60~300 s, and the hot pressing vacuum negative pressure is -0.09~-0.095MPa.

10. The application of the fiber-molded composite material according to claim 1 or 2 or the fiber-molded composite material obtained by the preparation method according to any one of claims 3-9 in the preparation of environmentally friendly, non-toxic, and fully biodegradable materials.

Images