Preparation method of bamboo fiber mixed with phenolic resin molded composite material

Abstract

The invention discloses a preparation method of a bamboo fiber mixed with phenolic resin molded composite material, comprising the following steps: S1, removing lignin and hemicellulose from a plurality of bamboo fibers; S2, mixing brown oligosaccharide and salt particles and evenly distributing them on the bamboo fibers; S3, spraying water on the surface of the bamboo fibers to obtain a bamboo fiber coated structure and subjecting the bamboo fibers to microwave radiation treatment, so that the generated oxygen functional groups and salt particles generate attraction, and the salt particles and brown oligosaccharide are attracted to the pores of the bamboo fibers to obtain a reinforced bamboo fiber structure; S4, soaking the reinforced bamboo fiber structure in a phenolic resin solution; S5, weaving a plurality of reinforced bamboo fiber structures into a bamboo fiber braided structure; S6, subjecting the composite material to molded curing treatment. The above preparation method subjects the bamboo fiber membrane structure to microwave radiation treatment with brown oligosaccharide and salt particles, activates the oxygen functional groups in the fibers and generates attraction with the salt particles, and further enhances the degree of fixation of the phenolic resin on the bamboo fibers.

Description

Technical Field

[0001] The invention relates to the field of bamboo composite materials, in particular to a method for preparing a bamboo fiber mixed with phenolic resin molded composite material. Background Art

[0002] Phenolic resin is a commonly used synthetic resin with high strength, excellent heat resistance and chemical resistance, so it is widely used in plastics, adhesives and coatings. Bamboo fiber is cellulose fiber extracted from naturally grown bamboo. Bamboo fiber has good air permeability, instant water absorption, strong wear resistance and good dyeability. It has natural antibacterial, antibacterial, mite removal, deodorization and UV resistance.

[0003] In recent years, the compounding of phenolic resin and fiber can give full play to the advantages of both and obtain new materials with higher performance and wider application fields; it can also reduce the cost of materials and environmental pollution. Therefore, in future material research, this composite material will be more widely used and developed.

[0004] The strength of fiber mixed with phenolic resin molding is usually anisotropic, that is, the strength in different directions is different; this may limit some applications, especially where uniform strength distribution is required; and bamboo fibers usually adopt a woven structure. The use of woven bamboo fiber materials can increase the strength directionality of the material and achieve a more uniform strength distribution; at the same time, the woven structure can provide more bamboo fiber cross points, increasing the strength and stiffness of the material; but the gaps in the weaving cannot be combined with the resin, resulting in the inability to guarantee the strength of the gaps.

[0005] Therefore, there is an urgent need to develop a bamboo fiber mixed phenolic resin composite material with uniform strength distribution and enhanced strength at the gap. Summary of the invention

[0006] The invention overcomes the shortcomings of the prior art and provides a method for preparing a bamboo fiber mixed with phenolic resin molded composite material.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a bamboo fiber mixed with phenolic resin molded composite material, comprising:

[0008] S1, removing lignin and hemicellulose from a plurality of bamboo fibers to obtain treated bamboo fibers;

[0009] S2, mixing brown oligosaccharide and salt particles, and evenly distributing the mixture on the bamboo fiber;

[0010] S3, spraying water onto the surface of the bamboo fiber in S2 to obtain a bamboo fiber coating structure, and subjecting the bamboo fiber coating structure to microwave radiation treatment, so that the generated oxygen functional groups and salt particles generate attraction, and the salt particles and brown oligosaccharides are attracted to the pores of the bamboo fiber to obtain a reinforced bamboo fiber structure;

[0011] S4, preparing a phenolic resin solution, and immersing the reinforced bamboo fiber structure into the phenolic resin solution;

[0012] S5, weaving the plurality of reinforced bamboo fiber structures in S4 to form a bamboo fiber woven structure;

[0013] S6, performing molding and curing treatment on the bamboo fiber woven structure, and obtaining a bamboo fiber mixed with phenolic resin molding composite material after cooling.

[0014] In a preferred embodiment of the present invention, in S2, the salt particles are magnesium sulfate particles, and the mass ratio of brown oligosaccharide to magnesium sulfate is 1:1.

[0015] In a preferred embodiment of the present invention, in said S3, when water is sprayed onto the surface of the bamboo fiber in S2, the spraying temperature is controlled between 50-70°C.

[0016] In a preferred embodiment of the present invention, in S3, when water is sprayed onto the surface of the bamboo fiber in S2, the spraying time is 15-25 minutes.

[0017] In a preferred embodiment of the present invention, in said S3, the microwave radiation treatment comprises the following steps:

[0018] S31, placing the bamboo fiber film-coated structure on a tray and placing it in a microwave device;

[0019] S32, setting the microwave power to 300-1000 W, the microwave duration to 1-10 min, and the microwave temperature to 50-100° C., and starting the microwave radiation treatment;

[0020] S33, cooling after the treatment is completed to obtain the reinforced bamboo fiber structure.

[0021] In a preferred embodiment of the present invention, in S4, the volume ratio of phenolic resin to solvent in the phenolic resin solution is 1:2-5, and the solvent is one of methanol, ethanol, ethylene glycol, butanol, acetone, dimethyl sulfoxide and dichloromethane, or a mixture of several of them in any proportion.

[0022] In a preferred embodiment of the present invention, in S4, the soaking time of the reinforced bamboo fiber structure in the phenolic resin solution is 1-2.5 hours.

[0023] In a preferred embodiment of the present invention, in S5, the bamboo fiber woven structure is formed by a needle punching method, and the needle punching density is 10-25 needles / cm 2 .

[0024] In a preferred embodiment of the present invention, in S6, the molding curing process comprises the following steps:

[0025] S61, removing bubbles from the bamboo fiber woven structure using a vacuum forming process, and placing the structure into a curing mold;

[0026] S62, adjusting the pressure of the hot press machine to 2-10 MPa, and hot pressing the bamboo fiber woven structure at a curing temperature of 150-180° C. for 5-20 minutes;

[0027] S63. After the bamboo fiber woven structure is naturally cooled, a bamboo fiber mixed with phenolic resin molded composite material is obtained.

[0028] In a preferred embodiment of the present invention, in S1, microwave treatment is used to remove lignin and hemicellulose.

[0029] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0030] (1) The present invention provides a method for preparing a bamboo fiber mixed with a phenolic resin molded composite material, wherein more pores are exposed by removing lignin and hemicellulose, and then a mixture of brown oligosaccharides and salt particles is applied to the outer wall of the bamboo fiber to form a membrane structure and subjected to microwave radiation treatment, followed by soaking in a phenolic resin solution and weaving, and finally subjected to a mold curing treatment, thereby ensuring the strength of the weaving gaps and improving the uniform distribution of the composite material's strength.

[0031] (2) The present invention removes part of the lignin and hemicellulose in the bamboo fiber by removing lignin and hemicellulose, thereby exposing more pores that can accommodate more of the mixture, so that the two form an integrated structure during the film-forming process, thereby improving the void capacity of the bamboo fiber, ensuring the integrity of the phenolic resin coating, and ensuring the effect and surface strength of the bamboo fiber composite material.

[0032] (3) The present invention treats the bamboo fiber coating structure through microwave radiation, thereby increasing the roughness and surface area of ​​the bamboo fiber surface, and at the same time greatly increasing the area that the phenolic resin can contact with it, which is beneficial to the mechanical anchoring effect of the surface; and the microwave radiation treatment can activate the oxygen functional groups in the fiber, generate attraction with the salt particles, and further enhance the fixation firmness of the phenolic resin on the bamboo fiber.

[0033] (4) The present invention uses brown oligosaccharide mixed with salt particles to fill the pores of bamboo fiber. When the brown oligosaccharide contacts a certain amount of water, it can form a viscose film on the outer wall of the bamboo fiber, thereby improving fluidity and playing a connecting role between the salt particles, bamboo fiber and resin. The salt particles used are magnesium sulfate particles, and the magnesium ions therein can further promote the film formation of brown oligosaccharide, thereby increasing the film formation speed and ensuring the effectiveness of the film formation.

[0034] (5) The present invention solves the problem in the prior art that the molded strength of fiber mixed with phenolic resin is usually anisotropic by connecting a plurality of reinforced bamboo fiber structures together through needle-punching and weaving. The strength of the bamboo fiber weaving gaps is also ensured through the treatment of the previous process, thereby greatly improving the strength of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 It is a specific flow chart of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0038] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0039] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, "multiple" means two or more.

[0040] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0041] like Figure 1 As shown, a flow chart of a method for preparing a bamboo fiber mixed with a phenolic resin molded composite material comprises:

[0042] S1, removing lignin and hemicellulose from a plurality of bamboo fibers to obtain treated bamboo fibers;

[0043] S2, mixing brown oligosaccharide and salt particles, and evenly distributing them on the bamboo fiber;

[0044] S3, spraying water onto the surface of the bamboo fiber in S2 to obtain a bamboo fiber coating structure, and subjecting the bamboo fiber coating structure to microwave radiation treatment, so that the generated oxygen functional groups and salt particles generate attraction, and the salt particles and brown oligosaccharides are attracted to the pores of the bamboo fiber to obtain a reinforced bamboo fiber structure;

[0045] S4, preparing a phenolic resin solution, and immersing the reinforced bamboo fiber structure in the phenolic resin solution;

[0046] S5, weaving the plurality of reinforced bamboo fiber structures in S4 to form a bamboo fiber woven structure;

[0047] S6. Performing molding and curing treatment on the bamboo fiber woven structure, and obtaining a bamboo fiber mixed with phenolic resin molding composite material after cooling.

[0048] The present invention provides a preparation method of a bamboo fiber mixed with phenolic resin molded composite material, which comprises the following steps: removing lignin and hemicellulose to expose more pores, applying a mixture of brown oligosaccharides and salt particles to the outer wall of the bamboo fiber to form a membrane structure and subjecting the fiber to microwave radiation treatment, then soaking the fiber in a phenolic resin solution and weaving the fiber, and finally subjecting the fiber to molded curing treatment, thereby ensuring the strength of the weaving gaps and improving the uniform distribution of the composite material's strength.

[0049] It should be noted that the use of microwave treatment to remove lignin and hemicellulose removes part of the lignin and hemicellulose in the bamboo fiber, exposing more pores that can accommodate more of the mixture, so that the two form an integrated structure during the film-forming process, thereby increasing the void capacity of the bamboo fiber, ensuring the integrity of the phenolic resin coating, and ensuring the effect and surface strength of the bamboo fiber composite material.

[0050] Among them, the salt particles are magnesium sulfate particles, which can further promote the film formation of brown oligosaccharide, increase the film formation speed, and ensure the effectiveness of film formation.

[0051] In S2, the mass ratio of the mixed brown oligosaccharide to magnesium sulfate is 1:1; and it should be noted that when spraying water onto the surface of the bamboo fiber, the spraying temperature is controlled between 50-70°C and the spraying time is 15-25min.

[0052] Brown oligosaccharide mixed with salt particles is used to fill the pores of bamboo fiber. When brown oligosaccharide comes into contact with a certain amount of water, it can form a viscose film on the outer wall of bamboo fiber, improve fluidity, and at the same time play a connecting role between salt particles, bamboo fiber and resin.

[0053] In S3, the microwave radiation treatment comprises the following steps:

[0054] S31, placing the bamboo fiber film-coated structure in a tray and placing the tray in a microwave device;

[0055] S32, setting the microwave power to 300-1000 W, the microwave duration to 1-10 min, and the microwave temperature to 50-100° C., and starting the microwave radiation treatment;

[0056] S33, cooling after the treatment is completed to obtain a reinforced bamboo fiber structure.

[0057] Treating the bamboo fiber coating structure with microwave radiation increases the roughness and surface area of ​​the bamboo fiber surface, while greatly increasing the area with which the phenolic resin can come into contact, which is beneficial to the mechanical anchoring effect of the surface; and microwave radiation treatment can activate the oxygen functional groups in the fiber, generating attraction with the salt particles, further enhancing the firmness of the fixation of the phenolic resin on the bamboo fiber.

[0058] In S4, the volume ratio of phenolic resin to solvent in the phenolic resin solution is 1:2-5, and the solvent is one of methanol, ethanol, ethylene glycol, butanol, acetone, dimethyl sulfoxide and dichloromethane, or a mixture of several of them in any proportion. It should be noted that the soaking time of the reinforced bamboo fiber structure in the phenolic resin solution is 1-2.5 hours.

[0059] In S5, the bamboo fiber woven structure is formed by needle punching with a needle punching density of 10-25 needles / cm 2 The problem that the fiber mixed phenolic resin molding strength is usually anisotropic in the prior art is solved, and the strength of the bamboo fiber weaving gaps is also guaranteed through the previous process, greatly improving the strength of the composite material.

[0060] In S6, the molding curing process includes the following steps:

[0061] S61, removing air bubbles from the bamboo fiber woven structure using a vacuum forming process, and placing the structure into a curing mold;

[0062] S62, adjusting the pressure of the hot press machine to 2-10 MPa, and hot pressing the bamboo fiber woven structure at a curing temperature of 150-180° C. for 5-20 minutes;

[0063] S63. After the bamboo fiber woven structure is naturally cooled, a bamboo fiber mixed with phenolic resin molded composite material is obtained.

[0064] Example 1

[0065] S1. Using a microwave treatment method to remove lignin and hemicellulose from a plurality of bamboo fibers to obtain treated bamboo fibers;

[0066] S2, weighing 50 g of brown oligosaccharide and 50 g of salt particles, mixing and evenly distributing the mixture on the bamboo fiber;

[0067] S3, controlling the spraying temperature at 65° C., spraying water onto the surface of the bamboo fiber in S2, and continuously spraying water for 20 minutes to obtain a bamboo fiber coating structure;

[0068] The microwave power was set to 550 W, the microwave duration was set to 6 min, and the microwave temperature was set to 85° C. The bamboo fiber coated structure was subjected to microwave radiation treatment, and after the treatment was completed, the structure was cooled to obtain a reinforced bamboo fiber structure. The oxygen functional groups generated during the microwave radiation process generated an attractive force with the salt particles, and the salt particles and brown oligosaccharides were attracted to the pores of the bamboo fiber to obtain a reinforced bamboo fiber structure.

[0069] S4, preparing a phenolic resin solution, fully stirring the liquid phenolic resin and ethanol in a volume ratio of 1:4, and immersing the reinforced bamboo fiber structure in the phenolic resin solution for 1.5 hours;

[0070] S5, performing needle punching and weaving on the several reinforced bamboo fiber structures in S4, with a needle punching density of 20 needles / cm 2 , a laminated bamboo fiber woven structure was obtained, wherein the density of the laminated three-dimensional bamboo fiber woven body was 0.36 g / cm 3 , length and width are both 45mm, thickness is 15mm;

[0071] S6. Use a vacuum forming process to remove bubbles from the bamboo fiber woven structure and place it in a curing mold, which is a flat mold. Adjust the hot pressure to 6 MPa and the curing temperature to 160°C to perform mold-curing treatment on the bamboo fiber woven structure. Continue hot pressing for 15 minutes, and obtain a bamboo fiber mixed phenolic resin molded composite material after cooling.

[0072] Firstly, the density of the bamboo fiber mixed with phenolic resin molded composite material was determined by density gradient column method, and the material density was measured to be 0.28 g / cm 3 ; Then use XQ-2 fiber strength and elongation tester to test the tensile strength. After calibrating the device, use pre-tension clamps to fix the fiber and stretch it after the upper and lower clamp jaws are closed; the tensile strength is measured to be 14.52MPa.

[0073] The fiber was installed in a compression test fixture using a micro-compression testing machine, and compression testing was carried out at a loading rate of 3 mm / min until the sample broke. The longitudinal compressive strengths were measured to be 2.67 MPa (10% strain stroke), 6.39 MPa (30% strain stroke), and 20.39 MPa (50% strain stroke).

[0074] Comparative Example 1

[0075] S1, preparing a phenolic resin solution, fully stirring the liquid phenolic resin and ethanol in a volume ratio of 1:4, and soaking the reinforced bamboo fiber structure in the phenolic resin solution for 1.5 hours;

[0076] S2. Needle punching and weaving the reinforced bamboo fiber structure, with a needle punching density of 20 needles / cm 2, a laminated bamboo fiber woven structure was obtained, wherein the density of the laminated three-dimensional bamboo fiber woven body was 0.36 g / cm 3 , length and width are both 45mm, thickness is 15mm;

[0077] S3. Use a vacuum forming process to remove bubbles from the bamboo fiber woven structure and put it into a curing mold, which is a flat mold; adjust the hot pressure to 6Mpa and the curing temperature to 160°C to perform mold curing on the bamboo fiber woven structure, continue hot pressing for 15 minutes, and obtain a bamboo fiber mixed phenolic resin molded composite material after cooling.

[0078] The density, tensile strength and longitudinal compressive strength were measured in the same manner as in Example 1. The material density of the bamboo fiber mixed with phenolic resin molded composite material was 0.25 g / cm 3 , tensile strength 8.73MPa, 1.37MPa (10% strain stroke), 2.23MPa (30% strain stroke), 5.68MPa (50% strain stroke). Therefore, it is shown that the preparation method of the present invention can not only improve the overall strength of the material, but also improve the strength of the fiber gap.

[0079] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A method for preparing a bamboo fiber mixed with phenolic resin molded composite material, characterized in that: The following steps are involved: S1, removing lignin and hemicellulose from a plurality of bamboo fibers to obtain treated bamboo fibers; S2, mixing brown oligosaccharide and salt particles, and evenly distributing them on the bamboo fiber, wherein the salt particles are magnesium sulfate particles, and the mass ratio of brown oligosaccharide to magnesium sulfate is 1:1; S3, spraying water onto the surface of the bamboo fiber in S2 to obtain a bamboo fiber coating structure, and subjecting the bamboo fiber coating structure to microwave radiation treatment, so that the generated oxygen functional groups and salt particles generate attraction, and the salt particles and brown oligosaccharides are attracted to the pores of the bamboo fiber to obtain a reinforced bamboo fiber structure; S4, preparing a phenolic resin solution, and immersing the reinforced bamboo fiber structure into the phenolic resin solution; S5, weaving the plurality of reinforced bamboo fiber structures in S4 to form a bamboo fiber woven structure; S6, performing molding and curing treatment on the bamboo fiber woven structure, and obtaining a bamboo fiber mixed with phenolic resin molding composite material after cooling.

2. The method for preparing a bamboo fiber mixed with phenolic resin molded composite material according to claim 1, characterized in that: In S3, when water is sprayed onto the surface of the bamboo fiber in S2, the spraying temperature is controlled between 50-70°C.

3. The method for preparing a bamboo fiber mixed with phenolic resin molded composite material according to claim 2, characterized in that: In S3, when water is sprayed onto the surface of the bamboo fiber in S2, the spraying time is 15-25 minutes.

4. The method for preparing a bamboo fiber mixed with phenolic resin molded composite material according to claim 1, characterized in that: In said S3, the microwave radiation treatment comprises the following steps: S31, placing the bamboo fiber film-coated structure on a tray and placing it in a microwave device; S32, setting the microwave power to 300-1000 W, the microwave duration to 1-10 min, and the microwave temperature to 50-100° C., and starting the microwave radiation treatment; S33, cooling after the treatment is completed to obtain the reinforced bamboo fiber structure.

5. The method for preparing a bamboo fiber mixed with phenolic resin molded composite material according to claim 1, characterized in that: In S4, the volume ratio of phenolic resin to solvent in the phenolic resin solution is 1:2-5, and the solvent is one of methanol, ethanol, ethylene glycol, butanol, acetone, dimethyl sulfoxide and dichloromethane, or a mixture of several of them in any proportion.

6. The method for preparing a bamboo fiber mixed with phenolic resin molded composite material according to claim 1, characterized in that: In S4, the reinforced bamboo fiber structure is immersed in the phenolic resin solution for 1-2.5 hours.

7. The method for preparing a bamboo fiber mixed with phenolic resin molded composite material according to claim 1, characterized in that: In S5, the bamboo fiber woven structure is formed by a needle punching method, and the needle punching density is 10-25 needles / cm 2 .

8. The method for preparing a bamboo fiber mixed with phenolic resin molded composite material according to claim 1, characterized in that: In said S6, the molding curing process comprises the following steps: S61, removing bubbles from the bamboo fiber woven structure using a vacuum forming process, and placing the structure into a curing mold; S62, adjusting the pressure of the hot press machine to 2-10 MPa, and hot pressing the bamboo fiber woven structure at a curing temperature of 150-180° C. for 5-20 minutes; S63. After the bamboo fiber woven structure is naturally cooled, a bamboo fiber mixed with phenolic resin molded composite material is obtained.

9. The method for preparing a bamboo fiber mixed with phenolic resin molded composite material according to claim 1, characterized in that: In S1, microwave treatment is used to remove lignin and hemicellulose.

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