CN118906562A - Composite paper pulp material and preparation method and application thereof - Google Patents

Abstract

The invention provides a composite paper pulp material, a preparation method and application thereof, and belongs to the technical field of paper pulp materials. The starch is gelatinized, reacted with vinyl acetate, reacted with 4-chloro-1, 1-trifluoro butane to prepare hydrophobic modified starch, then blended with microcrystalline cellulose and modified nanospheres to react, hot pressed to form a film, and hot pressed with handsheet to prepare the composite paper pulp material. The composite paper pulp material prepared by the invention has better mechanical property, reduced hydrophilic sensibility, low price, light weight, easy package, biodegradability, higher folding endurance, tensile strength and bonding strength, environmental protection and no pollution, and has wide application prospect.

Description

A composite pulp material and its preparation method and application

Technical Field

The invention relates to the technical field of pulp materials, and in particular to a composite pulp material and a preparation method and application thereof.

Background Art

The potential advantages of plant fiber as a reinforcing material are attracting more and more attention. It is rich in resources, low in price, and has a lower density than all inorganic fibers, while its modulus is similar to that of inorganic fibers. Its good mechanical and physical properties and environmental coordination characteristics are valued by the material science discipline. It has been applied to the automotive and aerospace industries. Plant fiber is widely valued because of its renewable, recyclable and biodegradable advantages. The application of pulp fiber composed of plant fibers in polymer composites is a relatively new field. The difference between pulp fiber and wood powder and rice straw used to fill ordinary plastics is that after pulping, the pulp has been treated to remove substances such as lignin that are harmful to polymer/plant fiber composites, leaving only the purer plant cellulose components.

The composite of waste paper and polymer generally adopts dry fiber crushing to crush the paper fiber into paper powder, and then mix and plasticize it with resin in a mixer or screw. In this process, the fibers of the waste paper raw material are severely damaged, and the pulp fibers are inevitably crushed. Therefore, this composite material is nothing more than simply using fiber powder as a filler. At the same time, due to the poor compatibility of the interface between the two, the function of the fiber cannot be fully exerted. From the perspective of papermaking technology, the fiber morphology or its strength is the main factor that constitutes the strength of the product. The strength of a single cellulose fiber is higher than that of aluminum, especially when the pulp fiber exists in a resin matrix in an absolutely dry state. As a reinforcing fiber, it is hoped that it can be in an ideal state of being absolutely dry and compatible with the polymer matrix interface. To effectively utilize the large aspect ratio of pulp fiber and its strength characteristics when absolutely dry, it is necessary to improve its surface properties and increase the compatibility of pulp fiber with polymer.

From the structural point of view, the pulp fiber structure is very different from other inorganic fibers. Pulp cellulose is a polysaccharide formed by many D-pyranose glucoses connected by 1,4-β glycosidic bonds. Among them, each base ring of the repeating unit of the cellulose macromolecule contains 3 hydroxyl groups (-OH). These hydroxyl groups form intramolecular hydrogen bonds or intermolecular hydrogen bonds, which make the fiber water-absorbent and the moisture absorption rate reaches 8-30%. Most of the thermoplastics are non-polar, hydrophobic, and have poor degradability and high cost. In addition, the compatibility between polymer and plant cellulose is very poor, the interfacial adhesion is very small, and the cellulose performance of water absorption is very poor. In the composite process of polymer/plant fiber material, the matrix resin must be able to well infiltrate the fiber, but due to the poor compatibility of the two, it is difficult to form a combination of physical or chemical bonds, the interface layer is very thin, and the interfacial tension is large. These problems all need to be improved.

Summary of the invention

The purpose of the present invention is to propose a composite pulp material and a preparation method and application thereof, which has good mechanical properties, reduced hydrophilic sensitivity, is cheap, light, easy to package, biodegradable, has high folding resistance, tensile strength and bonding strength, is environmentally friendly and pollution-free, and has broad application prospects.

The technical solution of the present invention is achieved in this way:

The invention provides a method for preparing a composite pulp material. The method comprises the following steps: gelatinizing starch, reacting the starch with vinyl acetate, and then reacting the starch with 4-chloro-1,1,1-trifluorobutane to obtain hydrophobically modified starch; then mixing the starch with microcrystalline cellulose and modified nanospheres for reaction, hot pressing the starch to form a film, and hot pressing the composite pulp material with hand-sheeted paper.

As a further improvement of the present invention, the following steps are included:

S1. Mix starch, glycerol and water evenly, heat and gelatinize to obtain gelatinized starch;

S2. The gelatinized starch was added to water, sodium tripolyphosphate was added, the pH value of the solution was adjusted, vinyl acetate was added, the reaction was heated with stirring, neutralized, washed, filtered, and dried to obtain gelatinized starch acetate;

S3. The gelatinized starch acetate and triethylamine were added to dichloromethane, a dichloromethane solution of 4-chloro-1,1,1-trifluorobutane was added dropwise, the reaction was heated and stirred, ethanol was added to precipitate, filtered, washed, and dried to obtain a hydrophobically modified starch;

S4. The hydrophobically modified starch, microcrystalline cellulose and modified nanospheres were added to a grinder and ground and mixed evenly, an initiator was added, melt-mixed by a twin-screw extruder to obtain a linear plastic, cut into masterbatches with a diameter of 2-3 mm, and hot-pressed into a film to obtain a modified film;

S5. Composite hot pressing of the hand-sheet paper made by hand-sheeting cork pulp and the modified film to obtain a composite pulp material.

As a further improvement of the present invention, the mass ratio of starch, glycerol and water in step S1 is 10:2-4:1-2, the heating gelatinization temperature is 120-140°C, and the time is 10-20min.

As a further improvement of the present invention, the mass ratio of gelatinized starch, sodium tripolyphosphate and vinyl acetate in step S2 is 10:1.5-2:2.5-3.5, the pH value of the adjusted solution is 9.5-10.5, the temperature of the heated and stirred reaction is 45-55°C, and the time is 60-90 min.

As a further improvement of the present invention, in step S3, the mass ratio of gelatinized starch acetate, triethylamine and 4-chloro-1,1,1-trifluorobutane is 10-15:3-5:4-7, and the temperature of the heating and stirring reaction is 40-50° C. and the time is 2-4 hours.

As a further improvement of the present invention, in step S4, the mass ratio of the hydrophobically modified starch, microcrystalline cellulose, modified nanospheres and initiator is 100:4-6:7-10:0.1-0.2, the grinding and mixing time is 20-30 min, the initiator is selected from at least one of sodium persulfate, potassium persulfate and ammonium persulfate, the melt mixing temperature is 130-140°C, the rotation speed is 100-200 r/min, the time is 5-10 min, the hot pressing temperature is 130-140°C, the pressure is 4-6 MPa/m ² , and the time is 10-20 min.

As a further improvement of the present invention, the preparation method of the modified nanospheres is as follows: 10 parts by weight of nano-silica spheres are added to ethanol, 1-2 parts by weight of a silane coupling agent, 3-4 parts by weight of tannic acid and 0.1-0.2 parts by weight of a catalyst are added, heated to 40-50° C., stirred for reaction for 2-4 hours, centrifuged, washed, and dried to obtain modified nanospheres; the silane coupling agent is KH570, and the catalyst is a Tris-HCl solution with a pH of 8.5-9.5.

As a further improvement of the present invention, the temperature of the composite hot pressing in step S5 is 100-110° C., the pressure is 4-6 MPa/m ² , and the time is 2-4 min.

The present invention further protects a composite pulp material obtained by the above preparation method.

The present invention further protects the use of the composite pulp material in packaging materials.

The present invention has the following beneficial effects:

Starch is a widely used biodegradable polymer. It is heated and gelatinized with water, glycerol glycol/sorbitol and other additives, and modified to obtain thermoplastic starch. Compared with other common thermoplastic polymers, thermoplastic starch has the advantages of biodegradability and low cost, but it also has the disadvantages of poor mechanical properties and high hydrophilicity. The paper-plastic composite material prepared by mixing with plastic has a barrier layer to protect the paper from moisture (or oil resistance), so that the material can meet the food packaging requirements of water-containing or oil-containing foods. Paper-plastic composite materials are non-toxic, odorless, and highly durable. Compared with other packaging materials such as metal cans, glass, and ceramics, it has the advantages of being cheap, light, and easy to package. However, due to the strong water absorption of starch, the mechanical properties of the obtained material are significantly reduced.

In order to overcome this shortcoming, the present invention adopts small-size material reinforcement technology to provide uniform strength throughout the composite material and ensure the biodegradability of the starch-based composite material. At the same time, the present invention adopts hydrophobic modified starch to greatly reduce the hydrophilicity of starch and the absorption rate, thereby significantly improving the effect on mechanical properties.

The present invention heats and gelatinizes starch, thereby reducing the solubility of starch and making it difficult to be acted upon by enzymes. The molecules of amylose and amylopectin tend to be arranged in parallel, and are combined by hydrogen bonds, close to each other, and recombined into microcrystalline bundles, so that the starch has a rigid overall structure, and further reacts with vinyl acetate to form ester compounds, thereby reducing the hydroxyl content in the starch and reducing its hydrophilicity. At the same time, the solubility in organic solvents is increased. The introduced double bonds can also react with the modified nanospheres under the action of an initiator, thereby increasing the compatibility of the two, and further increasing the mechanical properties, folding resistance, tensile strength, bonding strength, and the like of the material.

The present invention further reacts the prepared gelatinized starch acetate with 4-chloro-1,1,1-trifluorobutane, and the prepared hydrophobic modified starch has good hydrophobic and oleophobic properties, and the prepared packaging material is not easy to be polluted, not easy to be dirty, and easy to clean. At the same time, the hydrophilicity of the starch is greatly reduced, and the water absorption rate is greatly reduced, thereby significantly improving the mechanical properties.

The microcrystalline cellulose added in the present invention is prepared by acid hydrolysis of cellulose, which can remove most of the amorphous regions, resulting in the formation of a crystalline part, and is therefore insoluble in water. Its high crystallinity can support the reinforcing ability generated by high modulus, thereby improving the mechanical properties of the composite material and reducing the high water sensitivity of the composite material.

The invention prepares a modified nanosphere, the surface of which is modified by a silane coupling agent KH570 with double bonds and tannic acid, so that the prepared modified nanosphere can form hydrogen bonds and can be well combined with starch particles, thereby strengthening the performance of starch materials, thereby improving the bonding strength and mechanical properties, and at the same time, the double bonds can also polymerize with the double bonds on the starch and be evenly dispersed on the starch molecular chain, thereby improving the compatibility and improving the modification effect.

The composite pulp material prepared by the invention has good mechanical properties, reduced hydrophilic sensitivity, is cheap, light, easy to package, biodegradable, has high folding resistance, tensile strength and bonding strength, is environmentally friendly and pollution-free, and has broad application prospects.

DETAILED DESCRIPTION

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.

Nano-silica spheres, with an average particle size of 100 nm, were purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.

Starch is corn starch with a water content of 14-15 wt %, purchased from Shanghai Quanwang Biotechnology Co., Ltd.

Microcrystalline cellulose, with an average molecular weight of 30,000-32,000 and a particle size of 20-100 μm, was purchased from Hebei Hengao Biotechnology Co., Ltd.

Preparation Example 1 Preparation of modified nanospheres

The method is as follows: 10 g of nano-silica spheres are added to 200 mL of ethanol, 1.5 g of silane coupling agent KH570, 3.5 g of tannic acid and 0.15 g of catalyst are added, heated to 45° C., stirred for reaction for 3 h, centrifuged, washed and dried to obtain modified nano-spheres;

The catalyst is a Tris-HCl solution with a pH of 8.5-9.5.

Example 1

This embodiment provides a method for preparing a composite pulp material, comprising the following steps:

S1. Mix 10 g starch, 2 g glycerol and 1 mL water, heat to 120 ° C, and stir for 10 min to obtain gelatinized starch;

S2. 10 g of gelatinized starch was added to 200 mL of water, 1.5 g of sodium tripolyphosphate was added, the pH value of the solution was adjusted to 9.5, 2.5 g of vinyl acetate was added, heated to 45 ° C, stirred for 60 min, neutralized, washed, filtered, and dried to obtain gelatinized starch acetate;

S3. 10 g of gelatinized starch acetate and 3 g of triethylamine were added to 200 mL of dichloromethane, 50 mL of a dichloromethane solution containing 4 g of 4-chloro-1,1,1-trifluorobutane was added dropwise, heated to 40 ° C, stirred for 2 h, an equal volume of ethanol was added for precipitation, filtered, washed, and dried to obtain a hydrophobically modified starch;

S4. 100 g of hydrophobically modified starch, 4 g of microcrystalline cellulose and 7 g of modified nanospheres prepared in Preparation Example 1 were added to a grinder and ground and mixed for 20 min, 0.1 g of sodium persulfate was added, and melt-mixed by a twin-screw extruder at a temperature of 130° C., a rotation speed of 100 r/min, and a time of 5 min to obtain a linear plastic, which was cut into masterbatches with a diameter of 2 mm, and hot-pressed into films at a temperature of 130° C., a pressure of 4 MPa/m ² , and a time of 10 min to obtain a modified film;

S5. The hand-made softwood pulp hand-made paper (1 mm thick) and the modified film (1 mm thick) were hot-pressed at a temperature of 100° C., a pressure of 4 MPa/m ² , and a time of 2 min to obtain a composite pulp material.

Example 2

This embodiment provides a method for preparing a composite pulp material, comprising the following steps:

S1. 10 g starch, 4 g glycerol and 2 mL water were mixed evenly, heated to 140 ° C, and stirred for 20 min to obtain gelatinized starch;

S2. 10 g of gelatinized starch was added to 200 mL of water, 2 g of sodium tripolyphosphate was added, the pH value of the solution was adjusted to 10.5, 3.5 g of vinyl acetate was added, heated to 55 ° C, stirred for 90 min, neutralized, washed, filtered, and dried to obtain gelatinized starch acetate;

S3. 15 g of gelatinized starch acetate and 5 g of triethylamine were added to 200 mL of dichloromethane, 50 mL of a dichloromethane solution containing 7 g of 4-chloro-1,1,1-trifluorobutane was added dropwise, heated to 50 ° C, stirred for 4 h, an equal volume of ethanol was added for precipitation, filtered, washed, and dried to obtain a hydrophobically modified starch;

S4. 100 g of hydrophobically modified starch, 6 g of microcrystalline cellulose and 10 g of the modified nanospheres prepared in Preparation Example 1 were added to a grinder and ground and mixed for 30 min, 0.2 g of potassium persulfate was added, and melt-mixed by a twin-screw extruder at a temperature of 140° C., a rotation speed of 200 r/min, and a time of 10 min to obtain a linear plastic, which was cut into masterbatches with a diameter of 3 mm, and hot-pressed into films at a temperature of 140° C., a pressure of 6 MPa/m ² , and a time of 20 min to obtain a modified film;

S5. The hand-made softwood pulp hand-made paper (thickness 1 mm) and the modified film (thickness 1 mm) were hot-pressed at a temperature of 110° C., a pressure of 6 MPa/m ² , and a time of 4 min to obtain a composite pulp material.

Example 3

This embodiment provides a method for preparing a composite pulp material, comprising the following steps:

S1. Mix 10 g starch, 3 g glycerol and 1.5 mL water, heat to 130 ° C, and stir for 15 min to obtain gelatinized starch;

S2. 10 g of gelatinized starch was added to 200 mL of water, 1.7 g of sodium tripolyphosphate was added, the pH value of the solution was adjusted to 10, 3 g of vinyl acetate was added, heated to 50 ° C, stirred for 75 min, neutralized, washed, filtered, and dried to obtain gelatinized starch acetate;

S3. 12 g of gelatinized starch acetate and 4 g of triethylamine were added to 200 mL of dichloromethane, 50 mL of a dichloromethane solution containing 5.5 g of 4-chloro-1,1,1-trifluorobutane was added dropwise, heated to 45 ° C, stirred for 3 h, an equal volume of ethanol was added for precipitation, filtered, washed, and dried to obtain a hydrophobically modified starch;

S4. 100 g of hydrophobically modified starch, 5 g of microcrystalline cellulose and 8.5 g of the modified nanospheres prepared in Preparation Example 1 were added to a grinder and ground and mixed for 25 min, 0.15 g of ammonium persulfate was added, and melt-mixed by a twin-screw extruder at a temperature of 135° C., a rotation speed of 150 r/min, and a time of 7 min to obtain a linear plastic, which was cut into masterbatches with a diameter of 2.5 mm, and hot-pressed into films at a temperature of 135° C., a pressure of 5 MPa/m ² , and a time of 15 min to obtain a modified film;

S5. The hand-made softwood pulp hand-made paper (1 mm thick) and the modified film (1 mm thick) were hot-pressed at a temperature of 105° C., a pressure of 5 MPa/m ² , and a time of 3 min to obtain a composite pulp material.

Comparative Example 1

Compared with Example 3, the difference is that step S1 is not performed.

The details are as follows:

S1. Add 10 g of starch to 200 mL of water, add 1.7 g of sodium tripolyphosphate, adjust the pH value of the solution to 10, add 3 g of vinyl acetate, heat to 50 ° C, stir and react for 75 minutes, neutralize, wash, filter, and dry to obtain starch acetate;

S2. 12 g starch acetate and 4 g triethylamine were added to 200 mL dichloromethane, 50 mL of dichloromethane solution containing 5.5 g 4-chloro-1,1,1-trifluorobutane was added dropwise, heated to 45 ° C, stirred for 3 h, an equal volume of ethanol was added for precipitation, filtered, washed, and dried to obtain a hydrophobically modified starch;

S3. 100 g of hydrophobically modified starch, 5 g of microcrystalline cellulose and 8.5 g of the modified nanospheres prepared in Preparation Example 1 were added to a grinder and ground and mixed for 25 min, 0.15 g of ammonium persulfate was added, and melt-mixed by a twin-screw extruder at a temperature of 135° C., a rotation speed of 150 r/min, and a time of 7 min to obtain a linear plastic, which was cut into masterbatches with a diameter of 2.5 mm, and hot-pressed into films at a temperature of 135° C., a pressure of 5 MPa/m ² , and a time of 15 min to obtain a modified film;

S4. The hand-made softwood pulp hand-made paper (1 mm thick) and the modified film (1 mm thick) were hot-pressed at a temperature of 105° C., a pressure of 5 MPa/m ² , and a time of 3 min to obtain a composite pulp material.

Comparative Example 2

Compared with Example 3, the difference is that step S2 is not performed.

The details are as follows:

S1. Mix 10 g starch, 3 g glycerol and 1.5 mL water, heat to 130 ° C, and stir for 15 min to obtain gelatinized starch;

S2. 12 g of gelatinized starch and 4 g of triethylamine were added to 200 mL of dichloromethane, 50 mL of a dichloromethane solution containing 5.5 g of 4-chloro-1,1,1-trifluorobutane was added dropwise, heated to 45 ° C, stirred for 3 h, an equal volume of ethanol was added for precipitation, filtered, washed, and dried to obtain a hydrophobically modified starch;

S3. 100 g of hydrophobically modified starch, 5 g of microcrystalline cellulose and 8.5 g of the modified nanospheres prepared in Preparation Example 1 were added to a grinder and ground and mixed for 25 min, 0.15 g of ammonium persulfate was added, and melt-mixed by a twin-screw extruder at a temperature of 135° C., a rotation speed of 150 r/min, and a time of 7 min to obtain a linear plastic, which was cut into masterbatches with a diameter of 2.5 mm, and hot-pressed into films at a temperature of 135° C., a pressure of 5 MPa/m ² , and a time of 15 min to obtain a modified film;

S4. The hand-made softwood pulp hand-made paper (1 mm thick) and the modified film (1 mm thick) were hot-pressed at a temperature of 105° C., a pressure of 5 MPa/m ² , and a time of 3 min to obtain a composite pulp material.

Comparative Example 3

Compared with Example 3, the difference is that step S3 is not performed.

The details are as follows:

S1. Mix 10 g starch, 3 g glycerol and 1.5 mL water, heat to 130 ° C, and stir for 15 min to obtain gelatinized starch;

S2. 10 g of gelatinized starch was added to 200 mL of water, 1.7 g of sodium tripolyphosphate was added, the pH value of the solution was adjusted to 10, 3 g of vinyl acetate was added, heated to 50 ° C, stirred for 75 min, neutralized, washed, filtered, and dried to obtain gelatinized starch acetate;

S3. 100 g of gelatinized starch acetate, 5 g of microcrystalline cellulose and 8.5 g of the modified nanospheres prepared in Preparation Example 1 were added to a grinder and ground and mixed for 25 min, 0.15 g of ammonium persulfate was added, and melt-mixed by a twin-screw extruder at a temperature of 135° C., a rotation speed of 150 r/min, and a time of 7 min to obtain a linear plastic, which was cut into masterbatches with a diameter of 2.5 mm, and hot-pressed into films at a temperature of 135° C., a pressure of 5 MPa/m ² , and a time of 15 min to obtain a modified film;

S5. The hand-made softwood pulp hand-made paper (1 mm thick) and the modified film (1 mm thick) were hot-pressed at a temperature of 105° C., a pressure of 5 MPa/m ² , and a time of 3 min to obtain a composite pulp material.

Comparative Example 4

Compared with Example 3, the difference is that no modified nanospheres are added in step S4.

The details are as follows:

S1. Mix 10 g starch, 3 g glycerol and 1.5 mL water, heat to 130 ° C, and stir for 15 min to obtain gelatinized starch;

S2. 10 g of gelatinized starch was added to 200 mL of water, 1.7 g of sodium tripolyphosphate was added, the pH value of the solution was adjusted to 10, 3 g of vinyl acetate was added, heated to 50 ° C, stirred for 75 min, neutralized, washed, filtered, and dried to obtain gelatinized starch acetate;

S3. 12 g of gelatinized starch acetate and 4 g of triethylamine were added to 200 mL of dichloromethane, 50 mL of a dichloromethane solution containing 5.5 g of 4-chloro-1,1,1-trifluorobutane was added dropwise, heated to 45 ° C, stirred for 3 h, an equal volume of ethanol was added for precipitation, filtered, washed, and dried to obtain a hydrophobically modified starch;

S4. 100 g of hydrophobically modified starch and 13.5 g of microcrystalline cellulose were added to a grinder and ground and mixed for 25 min, 0.15 g of ammonium persulfate was added, and melt-mixed by a twin-screw extruder at a temperature of 135° C., a rotation speed of 150 r/min, and a time of 7 min to obtain a linear plastic, which was cut into masterbatches with a diameter of 2.5 mm, and hot-pressed into films at a temperature of 135° C., a pressure of 5 MPa/m ² , and a time of 15 min to obtain a modified film;

S5. The hand-made softwood pulp hand-made paper (1 mm thick) and the modified film (1 mm thick) were hot-pressed at a temperature of 105° C., a pressure of 5 MPa/m ² , and a time of 3 min to obtain a composite pulp material.

Comparative Example 5

Compared with Example 3, the difference is that no microcrystalline cellulose is added in step S4.

The details are as follows:

S1. Mix 10 g starch, 3 g glycerol and 1.5 mL water, heat to 130 ° C, and stir for 15 min to obtain gelatinized starch;

S2. 10 g of gelatinized starch was added to 200 mL of water, 1.7 g of sodium tripolyphosphate was added, the pH value of the solution was adjusted to 10, 3 g of vinyl acetate was added, heated to 50 ° C, stirred for 75 min, neutralized, washed, filtered, and dried to obtain gelatinized starch acetate;

S3. 12 g of gelatinized starch acetate and 4 g of triethylamine were added to 200 mL of dichloromethane, 50 mL of a dichloromethane solution containing 5.5 g of 4-chloro-1,1,1-trifluorobutane was added dropwise, heated to 45 ° C, stirred for 3 h, an equal volume of ethanol was added for precipitation, filtered, washed, and dried to obtain a hydrophobically modified starch;

S4. 100 g of hydrophobically modified starch and 13.5 g of modified nanospheres prepared in Preparation Example 1 were added to a grinder and ground and mixed for 25 min, 0.15 g of ammonium persulfate was added, and melt-mixed by a twin-screw extruder at a temperature of 135° C., a rotation speed of 150 r/min, and a time of 7 min to obtain a linear plastic, which was cut into masterbatches with a diameter of 2.5 mm, and hot-pressed into films at a temperature of 135° C., a pressure of 5 MPa/m ² , and a time of 15 min to obtain a modified film;

S5. The hand-made softwood pulp hand-made paper (1 mm thick) and the modified film (1 mm thick) were hot-pressed at a temperature of 105° C., a pressure of 5 MPa/m ² , and a time of 3 min to obtain a composite pulp material.

Test Example 1

The composite pulp materials prepared in Examples 1-3 and Comparative Examples 1-5 were tested for performance, and the hand-made paper made of softwood pulp was used as the base paper control. The test was conducted using a universal testing machine, and the sample (15 mm wide × 100 mm long) was mounted on a 50 mm composite material extension fixture. The tensile test was conducted at a speed of 10 mm/min. The results are shown in Table 1.

Table 1

It can be seen from the above table that the composite pulp materials prepared in Examples 1-3 of the present invention have good tensile strength, elongation at break, flatness and folding endurance.

Test Example 2: Hygroscopicity Test

The composite pulp materials prepared in Examples 1-3 and Comparative Examples 1-5 were cut into square sections (30×30 mm) and vacuum dried to constant weight. According to the determination of dry mass (M _d ), the samples were placed in saturated sodium bromide and calcium chloride at relative humidity (RH) of 75% and 95%, respectively. The mass (M _w ) of the sample was measured once every 24h and 48h. The water absorption rate was used as an indicator of hygroscopic performance and the water absorption rate (%) was calculated.

Water absorption (%) = ( _Mw - _Md )/ _Md × 100%

The results are shown in Table 2.

Table 2

It can be seen from the above table that the composite pulp materials prepared in Examples 1-3 of the present invention have a lower water absorption rate.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A process for preparing the composite paper pulp material includes such steps as gelatinizing starch, reaction with vinyl acetate, reaction with 4-chloro-1, 1-trifluorobutane to obtain hydrophobic modified starch, mixing with microcrystalline cellulose and modified nanospheres, reaction, hot pressing to become film, and hot pressing.

2. The method of manufacturing according to claim 1, comprising the steps of:

s1, uniformly mixing starch, glycerol and water, and heating for gelatinization to obtain gelatinized starch;

S2, adding gelatinized starch into water, adding sodium tripolyphosphate, adjusting the pH value of the solution, adding vinyl acetate, heating and stirring for reaction, neutralizing, washing, filtering and drying to obtain gelatinized starch acetate;

S3, adding gelatinized starch acetate and triethylamine into dichloromethane, dropwise adding a dichloromethane solution of 4-chloro-1, 1-trifluorobutane, heating and stirring for reaction, adding ethanol for precipitation, filtering, washing and drying to obtain hydrophobically modified starch;

S4, adding the hydrophobic modified starch and microcrystalline cellulose into a pulverizer, grinding and mixing uniformly, adding an initiator, carrying out melt mixing through a double-screw extruder to obtain linear plastic, cutting into master batches with the diameter of 2-3mm, and carrying out hot pressing to form a film to obtain a modified film;

s5, carrying out composite hot pressing on handsheets and modified films which are prepared by cork paper pulp handsheets to prepare a composite paper pulp material.

3. The preparation method according to claim 2, wherein the mass ratio of starch, glycerol and water in step S1 is 10:2-4:1-2, wherein the temperature of the heating gelatinization is 120-140 ℃ and the time is 10-20min.

4. The preparation method according to claim 2, wherein the mass ratio of the gelatinized starch, the sodium tripolyphosphate, and the vinyl acetate in the step S2 is 10:1.5-2:2.5-3.5, wherein the pH value of the solution is adjusted to 9.5-10.5, the temperature of the heating and stirring reaction is 45-55 ℃, and the time is 60-90min.

5. The preparation method according to claim 2, wherein the mass ratio of the gelatinized starch acetate, the triethylamine and the 4-chloro-1, 1-trifluorobutane in the step S3 is 10-15:3-5:4-7, the temperature of the heating and stirring reaction is 40-50 ℃ and the time is 2-4h.

6. The preparation method according to claim 2, wherein the mass ratio of the hydrophobically modified starch, the microcrystalline cellulose, the modified nanospheres, and the initiator in step S4 is 100:4-6:7-10:0.1-0.2, wherein the grinding and mixing time is 20-30min, the initiator is at least one selected from sodium persulfate, potassium persulfate and ammonium persulfate, the melting and mixing temperature is 130-140 ℃, the rotating speed is 100-200r/min, the time is 5-10min, the hot pressing temperature is 130-140 ℃, the pressure is 4-6MPa/m ², and the time is 10-20min.

7. The preparation method of the modified nanospheres according to claim 2, wherein the preparation method of the modified nanospheres comprises the following steps: adding 10 parts by weight of nano silicon dioxide balls into ethanol, adding 1-2 parts by weight of silane coupling agent, 3-4 parts by weight of tannic acid and 0.1-0.2 part by weight of catalyst, heating to 40-50 ℃, stirring and reacting for 2-4 hours, centrifuging, washing and drying to obtain modified nano balls; the silane coupling agent is KH570, and the catalyst is Tris-HCl solution with pH value of 8.5-9.5.

8. The method according to claim 2, wherein the composite hot press in step S5 is performed at a temperature of 100-110 ℃, a pressure of 4-6MPa/m ², and a time of 2-4min.

9. A composite pulp material produced by the production method according to any one of claims 1 to 8.

10. Use of the composite pulp material of claim 9 in packaging materials.