A plant fiber kneading treatment technology

Abstract

The present invention provides a plant fiber kneading treatment technology, comprising the following steps: (1) cutting and dispersing the plant fiber; (2) continuing to add powdered additives as ingredients to the plant fiber cut in step (1); wherein the powdered additives include surfactants, carbon nanotubes and nanocellulose; (3) adding 5% sodium carbonate to the mixture I obtained in step (2) and kneading and stirring; (4) drying the mixture II obtained in step (3) to obtain a plant fiber composite material. The present invention selects a variety of plant fibers for compounding, and improves the surface roughness and mechanical properties of the plant fibers by adding powdered additives and sodium carbonate, thereby improving the bonding strength of the plant fibers. Through a series of processes, the present invention can make natural plant fibers more resilient and improve the affinity for bonding with materials such as cement, gypsum, and lime.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a plant fiber kneading treatment technology. Background Art

[0002] Sustainable development involves the use of sustainable materials as substitutes for traditional materials to avoid excessive consumption of natural resources. Plant fiber, as a natural green material, is gradually being used in the production of architectural coatings and slurries such as tile adhesives, mortars, mortars, and wall paints due to its potential application value in composite materials. By introducing an appropriate amount of plant fiber, the toughness and strength of building materials can be improved. Plant fiber has many advantages, such as low price, abundant sources, flexible processing and use, low density, high strength-to-weight ratio, etc. Patent CN 111534173A discloses a plant fiber antibacterial coating and a preparation method, comprising the following components in parts by weight: 80-120 parts of acrylic emulsion, 100-120 parts of water, 2-5 parts of dispersant, 2-4 parts of defoamer, 20-40 parts of titanium dioxide, 5-8 parts of calcined kaolin, 24-32 parts of plant fiber, and 5-10 parts of plant extract; the plant fiber is a mixture of bamboo fiber, wormwood fiber or citronella fiber; the plant extract is an extract of aloe, mint, valerian or mulberry branch. The invention realizes an environmentally friendly coating with a long-lasting antibacterial effect. Patent CN 107629604A discloses a quick-drying architectural coating and a preparation method thereof, which is composed of the following components in parts by weight: 10-20 parts of plant ash extract, 1-3 parts of gypsum, 1-2 parts of coke powder, 5-8 parts of water-based acrylic emulsion, 7-12 parts of film-forming agent, 1-2 parts of plant fiber, 30-90 parts of water, 3-5 parts of thickener, and 2-5 parts of quick-drying agent. The coating prepared by the above formula of the present invention has the characteristics of rapid curing. The coating formed by brushing on the surface of the building wall can be quickly dried within 30-90 seconds, and the thickness is uniform, which solves the problem of slow curing of existing water-based coatings, and also reduces costs and simplifies the preparation method.

[0003] However, the low durability, poor adhesion and poor mechanical properties of plant fibers have greatly limited the practical application of plant fibers in the field of building materials. The affinity of natural plant fibers for combining with materials such as cement, gypsum and lime is not ideal. Summary of the invention

[0004] The purpose of the present invention is to provide a plant fiber kneading treatment technology, which applies natural plant fibers that have undergone a series of treatments to the production of building coatings and slurries such as tile adhesives, mortars, plasters, and wall paints, thereby improving the toughness and strength of building materials and improving affinity.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A plant fiber kneading treatment technology comprises the following steps:

[0007] (1) Cutting and dispersing the plant fibers;

[0008] (2) adding powdered additives as ingredients to the cut plant fiber in step (1); wherein:

[0009] The powdered additives include surfactants, carbon nanotubes and nanocellulose;

[0010] (3) adding 5% soda ash to the mixture I obtained in step (2), kneading and stirring;

[0011] (4) Drying the mixture II obtained in step (3) to obtain a plant fiber composite material.

[0012] In a preferred embodiment, the plant fibers include coconut shell fibers with a length of 1 mm, rice straw fibers with a length of 0.5 mm, wheat straw or rice straw fibers with a length of 0.2 mm, and wood waste pulp fibers with a length of 0.05 mm.

[0013] The plant fiber of the present invention is selected from coconut shell fiber with a length of 1mm, rice straw fiber with a length of 0.5mm, wheat straw or rice straw fiber with a length of 0.2mm, and wood waste paper pulp fiber with a length of 0.05mm. The inventor found that the plant fiber of the present invention can significantly increase the dynamic mechanical properties of the material, has a good improvement and strengthening effect on the mechanical strength, and significantly improves and optimizes the performance of building mortar materials, etc. The length of the fiber of the present invention is more conducive to the enhancement of tensile strength, toughness and bonding force. The inventor believes that the aspect ratio of the fiber is one of the main factors affecting mechanical properties. Different types of fibers have different structural characteristics. When the fiber length is too small, the existence of gaps and the weak bonding between the fiber and the rest of the material reduce the tensile strength and toughness. When the fiber length is too long, the specific surface area of ​​the fiber is small, which reduces the hydroxyl groups on the fiber surface, thereby weakening the bonding force between the fibers.

[0014] In a preferred embodiment, the steps are specifically:

[0015] (1) cutting and dispersing the grass fiber using a double-row plowshare dispersing device;

[0016] (2) adding powdered additives as ingredients to the cut plant fiber in step (1); wherein:

[0017] The powdered additives include surfactants, carbon nanotubes and nanocellulose;

[0018] (3) adding 5% soda ash to the mixture I obtained in step (2) and kneading and stirring in a double-row spiral kneading mixing device;

[0019] (4) Drying the mixture II obtained in step (3) using a belt-type electric heating baking device to obtain a plant fiber composite material.

[0020] In a preferred embodiment, in step (1), the plant fiber is sequentially impregnated with a coupling agent, cured and dried, and then cut and dispersed using a double-row plowshare dispersing device.

[0021] Preferably, the coupling agent comprises a silane coupling agent and a titanate coupling agent in a mass ratio of (2-3):1. Further preferably, the coupling agent comprises a silane coupling agent and a titanate coupling agent in a mass ratio of 2.4:1. Further preferably, the coupling agent comprises a silane coupling agent kh550 and a titanate coupling agent 201. The silane coupling agent kh550 was purchased from Yunsheng Chemical, and the titanate coupling agent HY201 was purchased from Kenrich Petrochemicals in the United States.

[0022] The present invention uses a coupling agent for pre-treatment to improve the compatibility between plant fibers and materials, improve the interfacial compatibility between plant fibers and polymers, increase tensile strength and toughness, and enhance the interfacial bonding force between plant fibers and polymers in building materials. The coupling agent can improve the mechanical strength of the plant fiber composite material of the present invention. Plant fibers contain a large number of cellulose molecules, and a large number of hydroxyl groups make the plant fibers hydrophilic. Through the coupling agent treatment, the compatibility with the organic interface is improved, the surface structure and characteristics of the treated plant fibers are changed, the bound water inside the fibers is reduced or the roughness of the fiber surface is improved, and the chemical bonding and mechanical bonding capabilities of the fibers are enhanced.

[0023] In a preferred embodiment, the powdery additive comprises the following components in parts by weight: 6 to 14 parts of a surfactant, 5 to 10 parts of carbon nanotubes and 4 to 8 parts of nanocellulose.

[0024] Preferably, the powdery additive comprises the following components in parts by weight: 10 parts of surfactant, 7 parts of carbon nanotubes and 6 parts of nanocellulose.

[0025] The present invention makes the composite material have excellent mechanical properties by adding powdery additives. Because the structure of the plant fiber is porous, the additives can fill the surface grooves of the plant fiber and improve the interface bonding between the plant fiber and the matrix of other components in the building material without damaging the strength and toughness of the plant fiber itself. At the same time, the nanomaterials are attached to the surface of the plant fiber to improve its surface roughness and mechanical properties, so that the bonding strength of the plant fiber is better. The inventors found that the carbon nanotubes and nanocellulose of the present invention can further improve the mechanical properties and bonding strength of the material.

[0026] Preferably, the carbon nanotubes have an inner diameter of 2-5 nm, a purity of >95%, a length of 10-30 um, a bulk density of 0.27 g / cm3, and a true density of 2.1 g / cm3. They were purchased from Xianfeng Nano, item number: 100228. The nanocellulose carboxyl content is 1.2-3.0 mmol / g, pH value is 7-8, and ash content is 17%; it is a white to off-white powder; its diameter is 4-10 nm, and its length is 200 nm. It was purchased from Western Iodine Laboratory, item number: SD-C916412.

[0027] The inner diameter and length of the carbon nanotubes affect the mechanical strength of the composite material. At the same time, the nanocellulose in the present invention is also used as a dispersant and a thixotropic agent, so that the carbon nanotubes and nanocellulose of the present invention have a greater chance of contacting with the plant fibers and are more closely combined.

[0028] In order to improve the performance of the plant composite material, in a preferred embodiment, the powdery additive is added in an amount of 5 to 20 wt % of the plant fiber.

[0029] Preferably, the powdered additive is added in an amount of 15 wt % of the plant fiber.

[0030] In a preferred embodiment, the surfactant is an anionic surfactant.

[0031] Preferably, the anionic surfactant is selected from sodium dodecyl sulfate and / or sodium dodecylbenzene sulfonate.

[0032] Further preferably, the anionic surfactant is selected from sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

[0033] Preferably, the anionic surfactant is selected from sodium dodecyl sulfate and sodium dodecylbenzene sulfonate, with a weight ratio of 1: 1. Sodium dodecyl sulfate was purchased from Merck 71725. Sodium dodecylbenzene sulfonate was purchased from Merck 289957.

[0034] The inventors found that the micelle structure formed by using the surfactant of the present invention has good stability and foaming performance, and at the same time plays the role of a dispersant, which can promote the full filling of nanomaterials into plant fibers. There are strong hydrogen bonds and electrostatic attraction between the nanomaterials added by the present invention, the surface energy is high, and the energy is in an unstable state, which easily causes the agglomeration of the nanomaterials in the polymer matrix. By adding a surfactant, the surface energy can be reduced, agglomeration can be avoided, and fluidity can be increased. The inventors found that the surfactant selected by the present invention has the best effect.

[0035] In a preferred embodiment, the time for cutting and dispersing in step (1) is 5 to 20 minutes; the time for stirring in step (2) is 10 to 30 minutes; and the time for kneading and stirring in step (3) is 10 to 40 minutes.

[0036] Preferably, the time for cutting and dispersing in step (1) is 15 minutes; the time for stirring in step (2) is 20 minutes; and the time for kneading and stirring in step (3) is 25 minutes.

[0037] In order to obtain a suitable moisture content of the plant fiber composite material and make the structure more stable, in a preferred embodiment, the baking temperature in step (4) is 50-100°C, the baking time is 20-80 minutes, and the moisture content of the plant fiber composite material is ≤2%. Preferably, the baking temperature in step (4) is 95°C, and the baking time is 50 minutes.

[0038] The inventors found that the cutting and dispersion time and stirring time have an impact on plant fibers. Appropriate process conditions reduce the porosity of the prepared composite material, enhance the interweaving force and hydrogen bond force between fibers, and make the composite material denser, forming a network structure interwoven in three-dimensional space.

[0039] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0040] 1. The present invention provides a plant fiber kneading treatment technology, which selects a variety of plant fibers for compounding, and treats them by adding powder additives and soda ash. After a series of processes, the natural plant fibers can be made more resilient, and the affinity for combining with materials such as cement, gypsum, and lime can be improved. The plant fibers of the present invention are selected from coconut shell fibers with a length of 1 mm, rice straw fibers with a length of 0.5 mm, wheat straw or rice straw fibers with a length of 0.2 mm, and wood waste paper pulp fibers with a length of 0.05 mm. The present invention pre-treats the plant fibers with a coupling agent to improve the compatibility between the plant fibers and the materials, improve the interface compatibility between the plant fibers and the polymer, and increase the tensile strength and toughness. At the same time, plant fibers contain a large number of cellulose molecules, and a large number of hydroxyl groups make plant fibers hydrophilic. Through coupling agent treatment, the compatibility with organic interfaces is improved, and the surface structure and properties of the treated plant fibers are changed. The inventors found that the pre-treated grass fibers are mixed and stirred with the specific powdered additives and soda ash of the present invention to produce unexpectedly excellent synergistic effects. The treated grass fibers can significantly increase the dynamic mechanical properties of the material, have a good improvement and strengthening effect on the mechanical strength, and significantly improve and optimize the performance of building mortar materials, etc.

[0041] 2. The present invention makes the composite material have excellent mechanical properties by adding powdery additives, and the carbon nanotubes and nanocellulose of the present invention can improve the mechanical properties and bonding strength of the material. By matching suitable surfactants, the micellar structure formed has good stability and foaming performance, and plays the role of dispersant at the same time, which can promote the nanomaterial to be fully filled into the plant fiber. There are strong hydrogen bonds and electrostatic attraction between the nanomaterials added by the present invention, the surface energy is high, and the energy is in an unstable state, which can easily cause the agglomeration of nanomaterials in the polymer matrix. The specific surfactant of the present invention can reduce the surface energy, avoid agglomeration, increase fluidity, and find that the surfactant selected by the present invention has the best addition effect through a large number of experiments by the inventors, and the composite effect with carbon nanotubes and nanocellulose is the best.

[0042] 3. The process parameters set by the present invention are more reasonable. The cutting and dispersion time and stirring time of a specific type of plant fiber are set so that the subsequent effect with powdered additives and soda ash is better matched. The state of the plant fiber after cutting has a better effect with the powdered additives and soda ash of the present invention. Suitable process conditions reduce the porosity of the prepared composite material, enhance the interweaving force and hydrogen bond force between the fibers, make the composite material denser, and form a network structure interwoven in three-dimensional space, which improves the mechanical strength and has better effects in subsequent practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The present invention is a flow chart of a plant fiber kneading processing technology.

[0044] Figure 2 This is a flow chart of a plant fiber kneading treatment technology according to Example 1.

[0045] In the figure, 1. plant fiber, 2. double-row plowshare type dispersing equipment, 3. powdered additives, 4. 5% concentration of soda ash, 5. double-row spiral kneading and mixing equipment, 6. belt-type electric heating baking equipment. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Example 1

[0048] This embodiment provides a plant fiber kneading treatment technology, comprising the following steps:

[0049] (1) The grass fiber is impregnated with a coupling agent at room temperature for 25 hours, cured at 140°C for 20 minutes, dried at 89°C for 4 hours, and then cut and dispersed for 15 minutes using a double-row plowshare dispersion device; wherein the grass fiber includes 1 mm coconut shell fiber, 0.5 mm rice straw fiber, 0.2 mm wheat straw and 0.05 mm wood waste paper pulp fiber. The coupling agent includes silane coupling agent KH550 and titanate coupling agent 201, with a mass ratio of 2.4:1.

[0050] (2) Continue to add powdered additives as ingredients and stir for 20 minutes; wherein the powdered additives include the following components in parts by weight: 10 parts of surfactant, 7 parts of carbon nanotubes and 6 parts of nanocellulose. The amount of the powdered additive added is 15wt% of the plant fiber. The surfactant is sodium dodecyl sulfate and sodium dodecylbenzene sulfonate, and the weight ratio is 1:1.

[0051] (3) adding 5% soda ash, kneading and stirring in a double-row spiral kneading and mixing device for 25 minutes;

[0052] (4) Drying is performed using a belt-type electric heating baking equipment at a baking temperature of 95° C. for 50 minutes to obtain a plant fiber composite material.

[0053] Example 2

[0054] The difference between this embodiment and embodiment 1 is that the powdery additive comprises the following components in parts by weight: 6 parts of surfactant, 10 parts of carbon nanotubes and 4 parts of nanocellulose. The amount of the powdery additive added is 5wt% of the plant fiber.

[0055] Example 3

[0056] The difference between this embodiment and embodiment 1 is that the anionic surfactant is selected from sodium dodecyl sulfate; the coupling agent includes a silane coupling agent and a titanate coupling agent, and the mass ratio is 3:1.

[0057] Example 4

[0058] The difference between this embodiment and embodiment 1 is that the powdery additive comprises the following components in parts by weight: 14 parts of surfactant, 10 parts of carbon nanotubes and 4 parts of nanocellulose. The coupling agent comprises a silane coupling agent and a titanate coupling agent, with a mass ratio of 2:1.

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 1 is that the plant fiber is not pre-treated with a coupling agent, but is directly cut and dispersed using a double-row plowshare dispersing device for 15 minutes.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is that no powdery additive is added.

[0063] Comparative Example 3

[0064] The difference between this comparative example and Example 1 is that the powdery additive comprises the following components in parts by weight: 20 parts of surfactant, 3 parts of carbon nanotubes and 12 parts of nanocellulose. The powdery additive is added in an amount of 3 wt% of the plant fiber.

[0065] Comparative Example 4

[0066] The difference between this comparative example and Example 1 is that the plant fiber includes 5 mm coconut shell fiber, 1 mm rice straw fiber, 0.5 mm rice straw fiber and 0.1 mm wood waste paper pulp fiber. The coupling agent includes silane coupling agent and titanate coupling agent, and the mass ratio is 0.5:1.

[0067] Performance Testing

[0068] The plant fiber composite material prepared in the embodiment and the comparative example is used to prepare a coating, wherein the coating comprises the following components by mass percentage: 50% waterborne epoxy resin, 7% curing agent, 5% ethylene glycol butyl ether, 10% plant fiber composite material, 12% zinc phosphate, 1% barium dinonylnaphthalenesulfonate, and the balance is silane coupling agent KH550. After the coating is formed, the coating is tested with reference to GB / T5210-2006, and the results are shown in Table 1.

[0069] Table 1 Performance test results

[0070] project Impact resistance / kg.m Adhesion / MPa Example 1 65 7.9 Example 2 61 7.5 Example 3 60 7.3 Example 4 62 7.6 Comparative Example 1 55 7.1 Comparative Example 2 52 6.5 Comparative Example 3 56 6.4 Comparative Example 4 53 6.7

[0071] As shown in Table 1, the coating prepared by the plant fiber composite material prepared by Examples 1 to 3 has high impact resistance and strong adhesion. In particular, the treatment technology of Example 1 has a significant improvement effect on the mechanical properties of the coating through the reasonable optimization of the treatment technology, as well as the combination of plant fiber, powdered additive and alkali solution. It can be seen from Example 1 and Comparative Example 1 that the treated plant fiber obtained by the special pre-treatment and cutting process of the plant fiber improves the compatibility between the plant fiber and the material, increases the tensile strength and enhances the toughness. At the same time, the coupling agent treatment improves the compatibility with the organic interface, and the surface structure and characteristics of the treated plant fiber are changed, and then mixed and stirred with the specific powdered additive and soda ash of the present invention to produce a synergistic effect. It can be seen from Example 1 and Comparative Example 2 that the use of powdered additives has an influence on impact resistance and adhesion, so that the composite material has excellent mechanical properties. It can be seen from Example 1 and Comparative Example 3 that the present invention promotes the full filling of nanomaterials into plant fibers through the composition and ratio of specific powder additives and the matching of suitable surfactants. Carbon nanotubes and nanocellulose can further improve the mechanical properties and bonding strength of the materials. Through the appropriate addition amount of powder additives, the three compounding plays the best role in improving quality and efficiency, and can avoid the waste of raw materials. It can be seen from Example 1 and Comparative Example 4 that the plant fibers selected by the present invention are of specific types and lengths. The inventor believes that the type of plant fiber itself will affect the overall mechanical properties of the plant fiber, and the amount of coupling agent is closely related to the special internal structure of different types of plant fiber. In order to ensure the excellent usability of plant fiber, the present invention has selected specific types of plant fibers and their lengths through a large number of creative experiments, and has been treated with coupling agents and dosages adapted thereto. It can be found from the results that the mechanical properties of the product of Example 1 of the present invention are significantly increased compared with Comparative Example 4. The present invention provides a plant fiber kneading treatment technology, which selects a variety of plant fibers for compounding, adds powder additives, and undergoes a series of processes to make the natural plant fibers more resilient and improve their affinity with materials such as cement, gypsum, and lime.

[0072] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for kneading plant fibers, characterized in that: The following steps are involved: (1) Cut and disperse the plant fibers; (2) adding powdered additives as ingredients to the cut grass fiber in step (1); wherein the powdered additives include surfactants, carbon nanotubes and nanocellulose; (3) Add 5% soda ash to the mixture I obtained in step (2), and knead and stir; (4) drying the mixture II obtained in step (3) to obtain a plant fiber composite material; The plant fibers include coconut shell fibers with a length of 1 mm, rice straw fibers with a length of 0.5 mm, wheat straw or rice straw fibers with a length of 0.2 mm, and wood waste paper pulp fibers with a length of 0.05 mm; In the step (1), the plant fiber is sequentially impregnated with a coupling agent, cured and then dried, and then cut and dispersed using a double-row plowshare dispersing device; the coupling agent includes a silane coupling agent and a titanate coupling agent, and the mass ratio is (2-3):1; The powdery additive comprises the following components in parts by weight: 6 to 14 parts of a surfactant, 5 to 10 parts of carbon nanotubes and 4 to 8 parts of nanocellulose; the added amount of the powdery additive is 5 to 20 wt % of the plant fiber.

2. A method for kneading plant fibers according to claim 1, characterized in that: The surfactant is an anionic surfactant.

3. A method for kneading plant fibers according to claim 1, characterized in that: The time for cutting and dispersing in step (1) is 5 to 20 minutes; the time for kneading and stirring in step (3) is 10 to 40 minutes.

4. A method for kneading plant fibers according to claim 3, characterized in that: In the step (4), the drying temperature is 50-100° C., the drying time is 20-80 minutes, and the moisture content of the plant fiber composite material is ≤2%.

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