CN113386233B

CN113386233B - Cellulose-based section bar and processing technology

Info

Publication number: CN113386233B
Application number: CN202010179204.1A
Authority: CN
Inventors: 尹应武; 任毅华; 赵升云; 师雪琴; 蔡成伟; 尹政清; 黄仁兵; 张海双; 赵玉芬
Original assignee: Th Unis Insight Co ltd; Xiamen University; Wuyi University
Current assignee: Th Unis Insight Co ltd; Xiamen University; Wuyi University
Priority date: 2020-03-13
Filing date: 2020-03-13
Publication date: 2022-08-09
Anticipated expiration: 2040-03-13
Also published as: CN113386233A

Abstract

The invention relates to a cellulose-based profile and a processing technology, wherein the profile comprises cellulose and a viscous polymer, the static bending strength of the profile is 40-150MPa, the elastic modulus is 4000-15000MPa, and the mass ratio of the cellulose to the viscous polymer is 1: (0.01-100). The paper pulp is used as a one-dimensional basic structure unit, lignin or synthetic material powder or common binder solution can be added for dispersion or impregnation, and a novel composite section or a special-shaped section can be produced by conventional operations such as drying, paving, hot pressing and the like. The invention takes biomacromolecule aggregation with one-dimensional fibrous structure characteristics in a plant tissue structure as a framework, expands the use of synthetic resin or acidified lignin as an adhesive, and can produce novel plates, pipes and profiled bars with high cost performance biobased materials as main components in large scale and at low cost by the processes of uniformly mixing a fiber material and the adhesive, drying to evaporate a large amount of water and hot press molding.

Description

Cellulose-based section bar and processing technology

Technical Field

The invention relates to the field of bio-based composite materials, in particular to a cellulose-based section bar and a processing technology thereof.

Background

The biomass material is the fundamental direction of future development of human beings, and can meet the requirements of environmental friendliness, ecological health, safe use and sustainable development. The biomass raw material is rich, and wood or bamboo buildings and furniture have thousands of years of use history. The biomass such as bamboo, straw and the like has the defects of bonding materials and low utilization rate due to different sizes, poor uniformity of structure and density and anisotropy. The papermaking technology of one of four ancient inventions in China realizes a major technical breakthrough of splitting plant raw materials into millimeter-grade unbleached pulp with uniform specification by an alkaline process, and provides a technical and industrial foundation for biomass recombination molding. However, the strength loss of the produced paper products and fiber products is serious, and the strength loss is difficult to greatly improve; the artificial fiber board produced by adding adhesives such as urea-formaldehyde resin or phenolic resin and the like into the fiber material and hot-pressing also has the problems of low strength, poor performance, formaldehyde hazard and the like. The strength of the composite polymer material can be greatly improved by taking the nanocellulose crystal obtained by completely removing lignin and hemicellulose in the plant raw material as a structural 'module', but the problems of complex production process, high production cost, high material consumption and energy consumption, difficulty in industrial application and the like still exist. The mechanical method developed in recent years breaks bamboo wood, and a recombined plate or a square timber with mechanical property 2-3 times higher than that of the original bamboo can be obtained through the processes of drying, impregnating urea-formaldehyde resin or phenolic resin, drying and hot pressing, thereby being a technical breakthrough of bamboo/wood processing. However, since the cell membrane is not completely destroyed, small molecules and ions which affect the adhesive force exist in the plant cell tissue only with water evaporated, the adhesive is difficult to fill the cells, the strength is improved limitedly, the bending stress is large, and the adhesive is easy to deform and anisotropic. More importantly, the production and processing mode for manually processing the single bamboo slices has the series of bottleneck problems of low production efficiency, high energy consumption, high material consumption, high labor intensity, high processing cost, low automation level, difficulty in large-scale production and the like, which restrict the industrial development. Therefore, the existing biomass processing recombination technology needs to be broken through.

The processing method of the fiber plastic composite material using the fiber powder as the filler also has the problems of large reduction range of plastic strength, poor product toughness, small addition amount and the like. Although the technologies of hot-press molding and blending extrusion molding of wood-plastic materials with fibers and plastics as main components have simple production process, short period, high efficiency, stable product quality and lower production cost, cellulose, hemicellulose macromolecules and lignin macromolecules in natural fibers contain a large amount of strongly polar hydroxyl groups and ether bonds, are easy to agglomerate, have poor miscibility with thermoplastic nonpolar or weakly polar polymers such as Polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and the like, are difficult to disperse, have poor fluidity, are difficult to process, and have the technical problems of influencing the development of the wood-plastic materials, particularly series of low toughness and the like, which need to be solved.

Patent document CN1168591C discloses a composite material prepared from a composite of polymer, fiber and pulp fiber, wherein the final composite material contains 30-40% of fiber, wherein the polymer is PP, LDPE, HDPE, PS, and the cellulose fiber is annual plant fiber or bast fiber, such as flax, hemp, jute, kenaf, etc., but the strength of the profile prepared by the method and the paper fiber used is low, and the purpose of replacing high-density fiberboard cannot be achieved.

Therefore, the composite material which has wide source, environmental protection and low cost and is made of plant raw materials and processing residues and synthetic resin with excellent production performance and low cost has great significance.

The black liquor-free pulping process (ZL201210209351.4) invented in the earlier stage of the research and development team can be used for separating alkali generated by various plant raw materials through a double decomposition method and carrying out acidification and precipitation, and can be used for producing unbleached pulp and high-strength unbleached paper which have one-dimensional structure characteristic, micron-level length and are rich in natural binder components such as lignin and the like at low cost, so that the energy consumption and material consumption are greatly reduced, pulping pollution is eliminated, a natural lignin macromolecular structure is reserved to the greatest extent, and a good technical and raw material basis is laid for the invention.

Disclosure of Invention

The invention aims to give full play to the high-strength mechanical property of unbleached pulp separated from bamboo/wood materials, solve the series problems of low strength of artificial fiber boards, difficult mixing of wood-plastic materials, low addition of fiber materials, difficult uniform mixing of resin and fiber materials, influence on strength due to loss of water in high-temperature hot pressing and the like, solve the problems of low strength of urea-formaldehyde resin, phenolic resin and soybean protein resin binders, use of a series of bio-based composite materials such as formaldehyde toxicity and the like, and develop a novel technology for developing adhesives, bio-based materials and recombination molding, wherein the adhesives have high strength, are environment-friendly and good in flame retardant property.

In order to solve the technical problems and realize the technical problems, the invention provides a profile which is characterized by comprising cellulose and a viscous polymer, wherein the static bending strength of the profile is 40-150MPa, the elastic modulus is 4000-15000MPa, and the mass ratio of the cellulose to the viscous polymer is 1: 0.01-100.

Preferably, in the above-mentioned shaped material, the mass ratio of the cellulose to the adhesive polymer is 1: (0.1-10). It is particularly preferable that the mass ratio of the cellulose to the viscous polymer is 1: (0.1-5.0), it is particularly preferable that the mass ratio of the cellulose to the viscous polymer is 1: (0.2-4.0), and it is further preferable that the mass ratio of the cellulose to the viscous polymer is 1: (0.5-3.1).

Preferably, in the profile, the static bending strength of the profile is 45-120MPa, and the elastic modulus is 5000-12000 MPa. Particularly preferably, the strength of the section bar is 45-100MPa, and the elastic modulus is 5000-12000 MPa.

Preferably, in the above-mentioned profile, the thickness of the profile is in a range of 3.5mm or less when the strength and elastic modulus of the profile are measured.

Preferably, in the above-mentioned profile, the adhesive polymer contains acid-insoluble lignin, the acid-insoluble lignin accounts for 1 to 60% by mass of the profile, preferably, the acid-insoluble lignin accounts for 5 to 55% by mass of the profile, and particularly preferably, the acid-insoluble lignin accounts for 9.0 to 53.0% by mass of the profile.

Preferably, in the above-mentioned shaped material, the raw materials for preparing the shaped material are a material mainly containing cellulose and a viscous polymer, and the mass ratio of the material mainly containing cellulose to the viscous polymer is 1: 0.01-100.

In the above-mentioned shaped material, the mass ratio of the cellulose-based material to the viscous polymer is preferably 1: 0.1 to 10, and particularly preferably 1: 0.3 to 2.0.

Preferably, in the above-mentioned profile, the adhesive polymer is one or more of a natural adhesive polymer material and/or a synthetic adhesive polymer material, the natural adhesive polymer material is acid-insoluble lignin or calcium biobased sulfonate, the synthetic adhesive polymer material is selected from one or more of polypropylene (PP), Polyethylene (PE), polyvinyl chloride (PVC), polylactic acid (PLA), Polyamide (PA), polyethylene terephthalate (PET), urea-formaldehyde resin, phenol-formaldehyde resin, epoxy resin, soy protein glue, polyester, polyurethane, styrene-acrylic emulsion and isocyanate, preferably, the adhesive polymer contains acid-insoluble lignin, optionally, the adhesive polymer also contains other adhesive polymers besides acid-insoluble lignin, preferably, the other adhesive polymers besides acid-insoluble lignin are polypropylene added with polyvinyl alcohol or calcium biobased sulfonate, Polyethylene or polyvinyl chloride; preferably, the sticky polymer comprises acid-insoluble lignin carried by or supplemented to the cellulose-based material, and optionally, the sticky polymer further comprises other sticky polymers in addition to the acid-insoluble lignin.

Polyvinyl alcohol and calcium bio-sulfonate have the function of enhancing hydrogen bonds, and high polymers rich in hydroxyl groups such as polyvinyl alcohol and calcium bio-sulfonate can be added to improve the strength, the internal binding force and the water resistance by forming the hydrogen bonds.

Preferably, in the above section bar, the bio-based calcium sulfonate is one or more of cellulose calcium sulfonate, hemicellulose calcium sulfonate, starch calcium sulfonate, humic acid calcium sulfonate or chitin calcium sulfonate.

Preferably, in the profile, the material mainly containing cellulose is paper pulp, and the paper pulp is unbleached pulp rich in cellulose, hemicellulose and lignin.

Preferably, in the profile, the addition amount of the natural viscous polymer material or the synthetic viscous polymer material is 10-80% of the mass of the profile (such as a composite profile or a profiled bar), and the optimal addition amount is that the gaps among the skeleton units in the pulp can be filled; preferably, the natural or synthetic viscous polymer material is added in an amount of 10-50% of the mass of the profile (e.g. composite profile or profile); preferably, the synthetic adhesive polymer material is PVC, added in an amount of 20-50% of the mass of the profile (e.g. composite profile or profiled bar) and at the same time 5-20% of polyvinyl alcohol is added.

Preferably, in the above section bar, the pulp further comprises acid-insoluble lignin, wherein the mass sum of cellulose and hemicellulose accounts for 50-90% of the mass of the pulp, and the mass of the acid-insoluble lignin accounts for 10-80% of the mass of the pulp.

Preferably, in the above section, the pulp is produced by chemical pulping, mechanical pulping, semi-mechanical pulping, biological pulping or waste paper recycling pulping. Preferably, in the case where the pulp is produced by a process other than chemical pulping, 5-60% acid insoluble lignin or calcium biobased sulfonate may be added to the pulp.

Preferably, in the profile, the chemical pulping is a pulping process for producing unbleached pulp by a clean process for precipitating lignin.

Preferably, in the above section bar, the paper pulp is natural color pulp, bleached pulp or recycled paper pulp of plant raw materials.

Preferably, in the section bar, the natural color pulp of the plant raw material is bamboo wood natural color pulp with the water content of 40-70%, the pH value of 9-10 and the content of acid-insoluble lignin of 1-50%.

Preferably, in the sectional material, the natural color pulp of the plant raw material is prepared by a black liquor-free pulping process, cell membranes can be effectively removed and cytoplasm can be dissolved and washed out by alkali resolution and acidification precipitation, and the natural color pulp which is rich in cellulose, hemicellulose and lignin and has the length of one-dimensional structure characteristic micron and is provided with the natural viscous polymer acid-insoluble lignin is obtained with high yield.

The preparation process of the plant raw material unbleached pulp can greatly reduce energy consumption and material consumption, effectively avoids environmental pollution, furthest retains the macromolecular structure of natural lignin, and provides a good original technology and a raw material basis for development of a bio-based material and extension of an industrial chain.

Preferably, in the sectional material, in the natural color paste of the plant raw material, the mass ratio of the acid-insoluble lignin to the sum of the mass of the cellulose and the hemicellulose is (4-17) to (73-89), and the sum of the mass of the acid-insoluble lignin, the mass of the cellulose and the hemicellulose accounts for 77-99% of the mass of the natural color paste of the plant raw material.

Preferably, in the profile, the preparation method of the plant raw material unbleached pulp comprises the following steps: treating the plant material by adopting alkali with the mass concentration of less than 15 percent and at the temperature of less than 130 ℃ to avoid the degradation of hemicellulose and lignin, and further kneading and grinding the plant material to obtain unbleached pulp with the cellulose content of 40-80 percent, the hemicellulose content of 10-30 percent and the lignin content of 10-80 percent. Preferably, the plant material is bamboo, wood or plant straw.

Preferably, in the above-mentioned profile, the method for preparing the profile by using the above-mentioned pulp is: fully mixing paper pulp and viscous polymer, prepressing, drying and hot-pressing to prepare a profile, preferably, adding acidified lignin or mixing a synthetic viscous polymer material into the paper pulp to enable the acidified lignin to be uniformly adsorbed and dispersed on the surface of the slurry, filtering, drying, paving, and hot-pressing to form the profile, wherein the product has flame retardance; preferably, the acidified lignin is a sodium lignin-rich black liquor and the synthetic sticky polymer material is a synthetic sticky polymer powder or a synthetic sticky polymer solution.

Preferably, in the section, the mass ratio of the paper pulp to the viscous polymer is 1: 9-9: 1, the temperature is increased, the porosity is reduced, the strength of the obtained section is obviously improved, and the water resistance is increased; preferably, 5-20% polyvinyl alcohol or bio-based calcium sulfonate is added to the pulp. The weakening effect of the loss of bound water on the binding force in the material can be compensated by adding polyvinyl alcohol or calcium biobased sulfonate.

In the following text and in the detailed description, the adhesive polymer is also generally described as "glue" or "glue", and the acidified lignin is also used as glue.

Preferably, in the above section bar, the preparation method of the section bar is: and fully mixing the paper pulp and the viscous polymer, and then prepressing, drying and hot-pressing to prepare the profile.

The invention also provides a preparation method of the section, which is characterized in that the section is prepared by fully mixing the material mainly containing cellulose and the viscous polymer, and then pre-pressing, drying and hot-pressing.

Preferably, in the above preparation method, the hot pressing conditions are as follows: the temperature is 100 ℃ and 250 ℃, the pressure is 1.5-20Mpa, and the time is 5-60 minutes.

The invention also provides the use of the above-mentioned profile, characterized in that the profile is used as a substitute for support structure materials, reconstituted bamboo/wood, metal steel, high-density fiberboard, wood-plastic materials or plastics.

Preferably, in the above application, the outer layer of the profile can be coated with functional materials such as flame retardant, waterproof, metal, and facing materials.

Preferably, in the above use, characterized in that the profile is used as a substitute for high density fiberboard, wood plastic or plastic.

Researches show that the decomposition of hemicellulose and lignin can be well avoided by adopting the low-alkali-content plant raw materials which are split below 120 ℃, the high-strength natural color pulp with the cellulose, the hemicellulose and the lignin as main components can be obtained at high yield by kneading and grinding, the lignin can be uniformly adsorbed, precipitated and dispersed on the surface of the pulp by a simple method of supplementing pulping black liquor rich in lignin salt and then acidifying, the filtration is convenient, and the novel material with better performance than a high-density board can be obtained by drying the one-dimensional pulp framework raw material, paving and hot press molding. Therefore, the problem of difficult later-stage dispersion can be well solved by mixing resin or solution in the earlier stage of raw material filtration or drying, the powder of synthetic plastics such as PVC and the like is added into the water-dispersed slurry solution, uniform dispersion can be realized, the filtration is convenient, the high-performance composite section can be obtained by paving and hot-press molding after drying, and the good dispersion effect can be also achieved by spraying the synthetic resin powder or solution on the surface of the filtered fiber or in the air flow drying state.

The new composite material with performance superior to that of artificial board and wood plastic may be obtained through the material synthesis and post-treatment process and the plastic consumption may be reduced to below 40%.

The invention opens up a new way for utilizing biomass with high added value, such as straws, bamboo, wood processing residues and the like, solves the problems of difficult dispersion of fibers, incapability of adding a large amount of fibers, low product strength, poor toughness, large bending stress of recombined bamboo, easy deformation, serious anisotropy and the like in the existing various composite materials, develops natural high polymers and synthetic high polymer materials into safe and clean adhesives, develops a novel composite material series which mainly adopts bio-based raw materials and has obvious cost performance advantage, can better prepare pulp and paper and produce platforms and industrial chain advantages in the plastic industry, develops a new process for large-scale, low-cost, continuously and cleanly producing large-size, large-dosage and safe and green plates, sectional materials, pipes and special-shaped products, and can open up a circular economy industrial chain taking a new bio-based material with huge market potential as a leading factor.

The reason why the strength and the internal bonding force of the novel profile system are remarkably increased is that the nonpolar high-molecular viscous polymer powder is tightly bonded with the fiber unit through hot-pressing melting, pores are filled to the maximum extent, the lipophilicity and the strength of the fiber material can be increased by covering lignin on the surface of the fiber, the mutual solubility between the lignin and the viscous polymer is promoted, the polyhydroxy in fiber crystals, hemicellulose and lignin macromolecules can mutually form a hydrogen bond network, free polyhydroxy macromolecules such as water molecules, polyvinyl alcohol and the like are favorable for increasing the intra-molecular bonding force, and the strength of the profile is improved.

Researches show that the flowability of the synthesized viscous polymer and lignin is increased along with the increase of the hot pressing temperature, the moisture or air in the synthesized viscous polymer and the lignin further escapes, and the porosity is reduced, so that the strength of the section is improved along with the increase of the hot pressing temperature within the decomposition temperature of the viscous polymer, but the strength is reduced due to the excessively low water content, the addition of polyvinyl alcohol and the like can be compensated by the increase of the hydrogen bond effect, the performance can be further improved by surface paving resin or performing waterproof treatment on the surface after hot pressing, and the preferable water content is 0.01-5%.

The invention has the advantages of

The invention solves the series of difficult problems of difficult cellulose dispersion, small addition amount, low strength, large bending stress, easy deformation, anisotropy, formaldehyde pollution, poor flame retardance and the like in the composite fiber material, achieves the purposes of obviously reducing the production cost, greatly improving the strength and toughness of the composite material and can produce the safe and environment-friendly high-density fiberboard with the strength greatly higher than that of natural materials such as plastics, wood-plastic materials and the like.

Drawings

FIG. 1 is a schematic perspective view of a pulp-skeletal substrate of an example PVC-fiber composite;

the components in figure 1 are labeled: 1. unbleached pulp fibers; 2. a resin material;

FIG. 2 is a diagram of a PVC-unbleached pulp composite material.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the invention can be more readily understood by those skilled in the art. It should be noted that the present embodiment is illustrative, not restrictive, and the scope of the invention should not be limited thereby.

The thickness of the profiles prepared in the following examples was within 3.5mm during the measurement of properties.

Example 1:

1. boiling bamboo chips for 10-12h at 75 ℃ by using NaOH solution with the concentration of 13%, rubbing, softening and grinding to obtain bamboo unbleached pulp with the water content of 60% and the pH of 9-10, acidifying until the pH is 2-3, washing with clear water, screening pulp, defibering by using a fiber defiberizer, and preparing pulp with the pulp concentration of 1% for later use. The acidified natural bamboo pulp (dry weight basis) had a cellulose (hemicellulose-containing) content of 58.98% by mass and an acid-insoluble wood content of 23.96% by mass.

2. Adding PVC granules or PLA granules with the grain diameter of less than 300 meshes according to the proportion, uniformly mixing, aging, prepressing for 20min to obtain a pulp framework base material with the thickness of 15 +/-1 mm, drying at the temperature of less than 100 ℃, and referring to the attached figure 1 for a schematic diagram of the three-dimensional structure of the pulp framework base material of the PVC-fiber composite material.

3. The slurry framework base material is subjected to hot pressing, pressure maintaining and cooling to obtain a product, and the specific properties are shown in tables 1 and 2.

TABLE 1 preparation conditions and product Properties of PLA-Natural color paste materials

The results in table 1 show that: in the profile, when the amount of PLA added was about 15% and the mass ratio of the sum of the masses of PLA and acid-insoluble lignin to cellulose was about 0.72 (the mass ratio of cellulose to viscous polymer was 1.39), the static bending strength was 57MPa and the elastic modulus was 7100MPa, which were superior to the requirements for the static bending strength (42.0MPa) and the elastic modulus (3800MPa) of the high-humidity high-density fiberboard described in GB/T31765-2015.

TABLE 2 preparation conditions and product Properties of PVC-Natural color pastes

The results of table 2 show: under the condition that the PVC addition amount is about 30-60 percent and the mass ratio of the mass sum of the viscous polymer PVC and the acid-insoluble wood to the cellulose is about 1.14-3.05 (the mass ratio of the cellulose to the viscous polymer is 0.33-0.88), the hot pressing condition is 180-185 ℃, 5-10MPa, the static bending strength of the PVC-pulp composite material of hot pressing for 9-15min is up to 62.15MPa, the lowest is up to 43.41MPa, the elastic modulus is up to 5235MPa and the lowest is 3994MPa, the static bending strength (42.0MPa) and the elastic modulus (3800MPa) of the high-humidity high-density fiber board are better than the requirements of 24h water absorption thickness expansion rate (12.0 percent) required in GB/T31765 2015 for 24h water absorption thickness expansion rates of 3, 4, 5, 6, 7 and 9, even the lowest water absorption thickness expansion rate of 24h can reach the index of 1.91 percent.

Example 2:

1. the pulping process was the same as in step 1 of example 1 above.

2. Adding superfine CaCO in proportion ₄ Or/and CaSO ₄ The powder is mixed evenly, aged, pre-pressed for 20min and dried at the temperature of less than 100 ℃.

3. Adding PVA solution in certain proportion and drying at below 100 deg.c.

4. The slurry framework base material is subjected to hot pressing, pressure maintaining and cooling to obtain a product, and the specific properties are shown in Table 3.

TABLE 3 preparation conditions and product Properties of PVA-unbleached pastes

The results in table 3 show that: the PVA-fiber-based composite material with the addition amount of less than 15 percent, and under the condition that no nano calcium material is added, the static bending strength and the elastic modulus of the PVA-fiber-based composite material are far better than the requirements of the static bending strength (38.0MPa) and the elastic modulus (3900MPa) of a common high-density fiberboard described in GB/T31765-2015 when the mass ratio of the mass sum of the PVA of the viscous polymer and the acid-insoluble lignin to the cellulose is 0.69 (the mass ratio of the cellulose to the viscous polymer is 1.45).

Even if the PVA-fiber-based composite material is added with the amount of less than 15 percent, and the mass ratio of the mass sum of the viscous polymer PVA and the acid-insoluble lignin to the cellulose is about 0.85 (the mass ratio of the cellulose to the viscous polymer is about 1.18), the static bending strength and the elastic modulus of the composite material are far superior to the requirements of the static bending strength (38.0MPa) and the elastic modulus (3900MPa) of the common high-density fiberboard described in GB/T31765 2015 even if 10 percent of nano calcium-based material is added.

Example 3:

1. boiling wood chips for 10-12h at 75 ℃ by using 13% NaOH solution, kneading, softening and grinding the wood chips into pulp to obtain the woody color paste with the water content of 60% and the pH value of 9-10, and measuring the mass content of cellulose (containing hemicellulose) in the woody color paste (by dry weight) to be 83.07% and the content of acid-insoluble wood to be 6.02%. Supplementing byproduct sodium lignin solution, mixing uniformly according to proportion, acidifying, washing and drying.

2. Polyvinyl alcohol with the concentration of 2% is added according to a certain proportion, kraft paper with the thickness of 0.4mm is pasted on the upper layer and the lower layer, and 4g of styrene-acrylic emulsion is used as an adhesive layer.

3. The product is obtained by hot pressing, pressure maintaining and cooling, and the specific properties are shown in Table 4.

TABLE 4 preparation conditions and product Properties of the unbleached pulp Material

The results in table 4 show that: the sodium lignin, PVA, styrene-acrylic emulsion and acid-insoluble lignin contained in the unbleached pulp are taken as adhesive polymers together, so that the mass ratio of the adhesive polymers to cellulose is 0.77-1.46 (the mass ratio of the cellulose to the adhesive polymers is 0.69-1.30), the static bending strength and the elastic modulus of a hot-pressed product containing the woody pulp and the adhesive mainly containing the sodium lignin are far superior to the requirements of the static bending strength (38.0MPa) and the elastic modulus (3900MPa) of a common high-density fiberboard, and the hot-pressed product cannot be ignited and has excellent flame retardant property. The addition of polar PVA can further enhance performance.

Example 4:

1. boiling bamboo chips for 10-12h at 75 ℃ by using 13% Na0H solution, rubbing, softening and grinding the bamboo chips into bamboo unbleached pulp with the water content of 60% and the pH value of 9-10, acidifying the bamboo unbleached pulp until the pH value is 2-3, washing the bamboo unbleached pulp by using clear water, screening the pulp, taking 50g of unbleached pulp, adding styrene-acrylic emulsion with the solid content of 50%, adding cellulose calcium sulfonate solution with the solid content of 50% according to the mass proportion of the bamboo fiber pulp, uniformly mixing and drying the mixture to obtain a profile raw material mixture. Wherein the contents of cellulose and acid-insoluble lignin in the bamboo unbleached pulp are the same as those in example 1, and the addition amount of the styrene-acrylic emulsion and the addition amount of the calcium cellulose sulfonate are calculated by solid contents.

2. The section bar raw materials are mixed, hot-pressed, pressure-maintaining and cooled to obtain the product, and the specific process and the performance are shown in table 5.

TABLE 5 preparation conditions and product Properties of unbleached pulp materials

In table 5, the percentage content of the emulsion is the percentage content of the unbleached pulp, and the percentage content of the calcium cellulose sulfonate is the percentage content of the total mass of the dry matter of the raw material of the profile, by calculation, the profile prepared by table 5 has a mass ratio of the total mass of the emulsion, the calcium cellulose sulfonate and the acid-insoluble lignin in the unbleached pulp to the cellulose in the viscous polymer of 0.59 to 1.25 (the mass ratio of the cellulose to the viscous polymer is 0.80 to 1.71). That is, after the styrene-acrylic emulsion is added to the product and then the calcium cellulose sulfonate is added, the mass ratio of the cellulose to the viscous polymer in the section bar is 0.80-1.71, and the static bending strength and the elastic modulus of the material are far superior to the requirements of the static bending strength (38.0MPa) and the elastic modulus (3900MPa) of a common high-density fiberboard.

It should be emphasized that the embodiments described herein are illustrative and not restrictive, and thus the present invention is not limited to the embodiments shown in the description, but is intended to cover all modifications, equivalents, flow charts, and other technical fields using the technical equivalents of the present disclosure and the accompanying drawings.

Claims

1. A profile, characterized in that the profile comprises cellulose and an adhesive polymer, the static bending strength of the profile is 40-150MPa, the elastic modulus is 4000-15000MPa, and the mass ratio of the cellulose to the adhesive polymer with adhesive or film-forming properties is 1: (0.01-100), wherein the viscous polymer contains acid-insoluble lignin, and the acid-insoluble lignin accounts for 5-60% of the mass of the profile.

2. The profile as claimed in claim 1, wherein the static bending strength of the profile is 45-120MPa, the elastic modulus is 12000MPa and 5000-: (0.1-5.0).

3. The profile according to claim 1, wherein the preparation raw materials of the profile comprise a cellulose-based material and an adhesive polymer, and the mass ratio of the cellulose-based material to the adhesive polymer is 1 (0.01-100).

4. Profile according to any one of claims 1-3, characterized in that the adhesive polymer is one or more of a natural adhesive polymer material which is an acid insoluble lignin or a bio-based calcium sulfonate and/or a synthetic adhesive polymer material selected from one or more of polypropylene, polyethylene, polyvinyl chloride, polylactic acid, polyamide, polyethylene terephthalate, urea formaldehyde resin, phenol formaldehyde resin, epoxy resin, soy protein glue, polyester, polyurethane, styrene acrylic emulsion and isocyanate; the sticky polymer comprises acid-insoluble lignin and the sticky polymer comprises other sticky polymers besides acid-insoluble lignin.

5. The profile according to claim 4, characterized in that the other viscous polymer than the acid-insoluble lignin is polypropylene, polyethylene or polyvinyl chloride to which polyvinyl alcohol or bio-based calcium sulfonate is added; the viscous polymer comprises acid-insoluble lignin carried by or supplemented to the cellulose-based material.

6. The profile according to claim 3, characterized in that the cellulose based material is a pulp, which is a unbleached pulp rich in cellulose, hemicellulose and lignin.

7. The profile according to claim 6, wherein the unbleached pulp is plant raw material unbleached pulp, the plant raw material unbleached pulp is prepared by a pulping process without black liquor, cell membranes can be effectively removed and cytoplasm can be washed out by dissolution through alkali separation and acidification precipitation, and the unbleached pulp which has micron length and is rich in cellulose and hemicellulose and self-contained with natural viscous polymer acid-insoluble lignin and has one-dimensional fibrous structure characteristic is obtained with high yield.

8. The section bar according to claim 7, characterized in that the preparation method of the plant raw material unbleached pulp comprises the following steps: treating plant materials with alkali with the mass concentration of less than 15% at the temperature of less than 130 ℃ to avoid degradation of hemicellulose and lignin, and further kneading and grinding the plant materials into pulp to obtain unbleached pulp with the cellulose content of 40-80%, the hemicellulose content of 10-30% and the lignin content of 10-80%, wherein the plant materials are bamboo, wood or plant straws.

9. Profile according to any one of claims 6-8, characterized in that the profile is prepared by a method comprising: fully mixing paper pulp and viscous polymer, prepressing, drying and hot-pressing to prepare a profile, adding acidified lignin or mixing synthetic viscous polymer material into the paper pulp to enable the acidified lignin to be uniformly adsorbed and dispersed on the surface of the slurry, filtering, drying, paving, and hot-pressing to form the profile, wherein the product has flame retardance; the acidified lignin is a black liquor rich in sodium lignin, and the synthetic sticky polymer material is synthetic sticky polymer powder or synthetic sticky polymer solution.