CN104312480A - Lignin-based filler and preparation method and application of lignin-based filler - Google Patents

Abstract

The invention discloses a lignin-based filler and its preparation method and application, relates to the field of chemical industry, and aims to obtain a urea-formaldehyde resin adhesive filler with low production cost, ideal use effect, and capable of completely replacing flour. The main technical solutions are as follows: hydrolyzing agricultural and forestry biomass residues to obtain agricultural and forestry biomass residue powder; purifying industrial alkali lignin to obtain purified industrial alkali lignin powder; The residue powder is mixed with the industrial alkali lignin powder to obtain the lignin-based filler. The invention is mainly used as an additive of urea-formaldehyde resin adhesive.

Description

A kind of lignin-based filler and its preparation method and application

technical field

The invention relates to the field of chemical industry, in particular to a lignin-based filler and its preparation method and application.

Background technique

my country's wood-based panel industry is developing rapidly. At present, the output of wood-based panels ranks first in the world, and there is a steady growth trend. Wood-based panels are the industry with the largest amount of adhesives, and urea-formaldehyde resin has become the first choice for the wood-based panel industry due to its low price, and is currently the largest woodworking adhesive. In the production process of wood-based panels, some flour (20% to 30%) needs to be added to the urea-formaldehyde resin as a filler to improve the pre-compression performance of the adhesive, prevent glue penetration and glue shortage, and reduce the resin The internal stress of the adhesive layer after curing ensures the bonding strength. Therefore, the amount of flour consumed as a filler for wood-based panel adhesives is huge every year, and with the continuous rise of flour prices, the cost of wood-based panels will increase significantly. On the other hand, the use of flour as the filler of the adhesive not only causes a waste of food resources, but also is not conducive to the sustainable development of the wood-based panel industry.

At present, the substances used as flour substitutes for urea-formaldehyde resin adhesive fillers mainly include inorganic mineral powder fillers (such as gypsum, bentonite, calcium carbonate, etc.), organic powder fillers (such as shell powder, polyvinyl alcohol powder, methylol powder, etc.) Cellulose, etc.) or complexes of these two or more different substances. However, these fillers have some problems, such as using inorganic mineral powder as adhesive filler, which is prone to loose blanks after pre-pressing the adhesive, which affects the production efficiency of wood-based panels; using natural organic powder such as fruit shell powder as adhesive Not only the pre-pressing effect of the filler is not good, but also the strength of these powders is poor, resulting in poor mechanical properties of the adhesive layer after curing, and unsatisfactory bonding strength of wood-based panels; polyvinyl alcohol powder, hydroxymethyl cellulose and other synthetic organic matter are used as adhesives. Although the effect of additive filler is better, its cost is too high, be difficult to industrialization.

Contents of the invention

In view of this, the embodiment of the present invention provides a lignin-based filler and its preparation method and application, the main purpose of which is to obtain a urea-formaldehyde resin adhesive filler with low production cost, ideal use effect, and can completely replace flour.

According to the first aspect of the present invention, the present invention provides a kind of preparation method of lignin-based filler, comprising:

A, the agricultural and forestry biomass residues are hydrolyzed, including such steps as:

A1, mixing the agricultural and forestry biomass residues with an aqueous catalyst solution, the aqueous catalyst solution being any one or several acidic solutions of sulfuric acid solution, hydrochloric acid solution or acetic acid solution;

A2, hydrolyzing the mixed agricultural and forestry biomass residues and the aqueous catalyst solution;

A3, drying the agricultural and forestry biomass residue after hydrolysis treatment, and then pulverizing to obtain the agricultural and forestry biomass residue powder;

B, purifying industrial alkali lignin, including such steps as:

B1, dissolving the industrial alkali lignin in an alkaline solution;

B2, the pH value of the mixed solution obtained after dissolving is adjusted to acidity, and the industrial alkali lignin precipitate is precipitated;

B3, drying and pulverizing the precipitated industrial alkali lignin precipitate to obtain purified industrial alkali lignin powder;

C. Mixing the agricultural and forestry biomass residue powder and the industrial alkali lignin powder to prepare the lignin-based filler.

Optionally, the preparation method as described above, before A, also includes:

The agricultural and forestry biomass residues are pulverized to obtain the agricultural and forestry biomass residues with a particle diameter of 1-2 cm.

Optionally, the aforementioned preparation method, wherein the solid-to-liquid mass ratio when the agricultural and forestry biomass residues are mixed with the aqueous catalyst solution is 1:5-10.

Optionally, in the aforementioned preparation method, the temperature of the hydrolysis treatment in the step A2 is 120-200° C., the pressure is 0.5-2.0 MPa, and the duration is 0.5-4.0 h.

Optionally, in the aforementioned preparation method, in the step A1, the mass percent concentration of the aqueous catalyst solution is not greater than 9%.

Optionally, in the aforementioned preparation method, in the step B1, the alkaline solution is a NaOH solution with a pH>10.5.

Optionally, in the aforementioned preparation method, in the step B2, the pH value of the mixed solution is adjusted to pH=1.5-3.5.

Optionally, the preparation method as described above, wherein the particle size of the agricultural and forestry biomass residue powder and the industrial alkali lignin powder is 90-350 mesh.

Optionally, in the aforementioned preparation method, in the C, the mass ratio of mixing the agricultural and forestry biomass residue powder and the industrial alkali lignin powder is 0-1:0-1.

Optionally, the preparation method as described above, wherein,

The agricultural and forestry biomass residues include: any one or more of corn stalks, rice straws, wheat straws, corn cobs or bagasse;

The industrial alkali lignin includes: any one or more of poplar alkaline kraft lignin, corn cob industrial alkali lignin or straw alkaline pulping lignin.

According to the second aspect of the present invention, the present invention provides a lignin-based filler prepared by the above-mentioned preparation method provided in the first aspect of the present invention.

According to a third aspect of the present invention, the present invention provides a urea-formaldehyde resin adhesive, comprising:

Urea-formaldehyde resin and filler;

The filler is the lignin-based filler provided in the second aspect of the present invention.

Optionally, the aforementioned urea-formaldehyde resin adhesive, wherein the mass ratio of the urea-formaldehyde resin to the filler is 100:20-30.

According to the fourth invention of the present invention, the present invention provides a wood-based panel containing the urea-formaldehyde resin adhesive provided in the third aspect of the present invention.

By means of the above-mentioned technical solution, a lignin-based filler and its preparation method and application provided by the embodiment of the present invention are mixed with the agricultural and forestry biomass residue powder obtained after hydrolysis treatment and the industrial alkali lignin powder obtained after purification treatment, The preparation method is simple, the preparation cost is low, and it can completely replace flour, the main food resource, as an additive for adhesives in wood-based panel production; at the same time, the presence of lignin in the filler can be used to supplement formaldehyde. Compared with the existing technology, The adhesive using the lignin-based filler provided by the embodiment of the present invention can greatly reduce the formaldehyde emission of the wood-based panel. The invention expands the application range of agricultural and forestry biomass residues and industrial alkali lignin, and has excellent industrial application prospects.

The above description is only an overview of the technical solutions of the present invention. In order to understand the technical means of the present invention more clearly and implement them according to the contents of the description, the preferred embodiments of the present invention will be described in detail below.

Detailed ways

In order to further illustrate the technical means and functions adopted by the present invention to achieve the intended invention purpose, the detailed description is as follows in conjunction with preferred embodiments.

my country is a large agricultural country. Every year, agricultural and forestry production will produce a large amount of agricultural and forestry biomass residues. The representative ones are corn straw, rice straw, wheat straw, corn cob and bagasse. The annual consumption is much smaller than that of the year A large part of the production amount is discarded or burned, resulting in a great waste of resources and environmental pollution. On the other hand, my country's biorefinery industry also produces a large amount of industrial alkali lignin every year, and its rational utilization is also a problem that hinders the development of the biorefinery industry.

Since agricultural and forestry biomass residues contain a large amount of cellulose, hemicellulose and lignin, lignin itself is a kind of natural adhesive, which binds the fibers in the plant body and gives the plant structural rigidity and prevents pests and diseases. ability, and studies have shown that lignin can form a cross-linked structure through condensation reaction with formaldehyde. The texture of agricultural and forestry biomass itself is relatively soft, which has a positive effect on relieving the internal stress of the adhesive layer after curing. Therefore, the present invention provides the following embodiments, using agricultural and forestry biomass residues and industrial alkali lignin as raw materials to prepare adhesive fillers that can reduce formaldehyde emission and increase bonding strength.

As mentioned above, Embodiment 1 of the present invention provides a method for preparing a lignin-based filler, including: hydrolyzing agricultural and forestry biomass residues; purifying industrial alkali lignin; hydrolyzing the obtained agricultural and forestry The biomass residue powder is mixed with the industrial alkali lignin powder obtained after purification treatment to obtain the lignin-based filler. Wherein, the steps of hydrolysis treatment are as follows: mixing the agricultural and forestry biomass residues with an aqueous catalyst solution, the aqueous catalyst solution being any one or several acidic solutions of sulfuric acid solution, hydrochloric acid solution or acetic acid solution; mixing the agricultural and forestry biomass residues performing hydrolysis treatment with an aqueous catalyst solution; drying and pulverizing the agricultural and forestry biomass residue after the hydrolysis treatment to obtain the agricultural and forestry biomass residue powder. The steps of the purification treatment are as follows: dissolving the industrial alkali lignin in the alkaline solution; adjusting the pH value of the mixed solution obtained after dissolving to acidic, and depositing industrial alkali lignin precipitate; separating the precipitated industrial alkali lignin precipitate After drying, it is pulverized to obtain purified industrial alkali lignin powder.

Furthermore, before hydrolyzing the agricultural and forestry biomass residues, the agricultural and forestry biomass residues can also be pulverized to obtain agricultural and forestry biomass residues with a particle size of 1-2 cm. After the agricultural and forestry biomass residues are crushed and then hydrolyzed, the efficiency of the hydrolysis treatment can be improved, and the agricultural and forestry biomass residues can be hydrolyzed more thoroughly.

Further, the solid-to-liquid mass ratio when the agricultural and forestry biomass residues are mixed with the aqueous catalyst solution can be 1:5-10. Mixing in such a ratio can make the hydrolysis of the agricultural and forestry biomass residues more thorough and improve the efficiency of hydrolysis treatment. For example, a solid-to-liquid mass ratio of 1:10 can be used for mixing, and of course other mixing ratios can also be used, which is not limited in this specific embodiment.

Further, during the hydrolysis treatment, the temperature can be set to 120-200°C, the pressure can be set to 0.5-2.0 MPa, and the duration can be set to 0.5-4.0h. Using such hydrolysis treatment conditions can improve the hydrolysis efficiency of agricultural and forestry biomass residues. Efficiency, making it hydrolyzed more thoroughly. For example, the temperature can be set at 180° C., the pressure at 1.5 MPa, and the duration of 2 hours for hydrolysis treatment. Of course, other hydrolysis treatment conditions may also be used, which is not limited in this specific embodiment.

Further, the aqueous catalyst solution used in the hydrolysis treatment may be any one or more of sulfuric acid solution, hydrochloric acid solution or acetic acid solution, for example, sulfuric acid solution may be selected as the aqueous catalyst solution for the hydrolysis treatment. Of course, other acidic aqueous solutions can also be selected as the catalyst aqueous solution. The specific embodiment does not limit this.

Wherein, these acidic aqueous solutions are used as catalyst aqueous solutions, and their mass percent concentration is usually not greater than 9%. For example, a sulfuric acid solution with a mass percent concentration of 9% or 5% can be used as the aqueous catalyst solution. Of course, catalyst aqueous solutions with other mass percentage concentrations may also be used, which is not limited in this embodiment. In the specific implementation process, the mass percent concentration of the aqueous catalyst solution varies according to the catalyst used and the hydrolysis requirements. If acetic acid solution is used as the catalyst aqueous solution, its mass percent concentration can be increased compared with sulfuric acid solution. Usually, the mass percent concentration of the catalyst aqueous solution is within the range of 9%, the higher the concentration, the higher the catalytic efficiency, and when the mass percent concentration exceeds 9%, the catalytic efficiency decreases with the increase of the concentration.

Further, the alkaline solution used when industrial alkali lignin is dissolved in the alkaline solution can be NaOH solution with pH>10.5, of course, KOH solution or other alkaline solutions can also be used, and the use of NaOH solution relative to other alkaline solutions low cost. Wherein, the pH value of the alkaline solution may be greater than 10.5, of course, may also be greater than 10 or greater than 9, as long as the industrial alkali lignin can be dissolved in the alkaline solution. The use of alkaline solution with pH>10.5 can make industrial alkali lignin dissolve more fully. In this embodiment, the pH value of the alkaline solution and the type of alkali are not limited. In a specific implementation process, NaOH solution with pH=11 can be used as the alkaline solution for dissolving industrial alkali lignin.

Further, after the industrial alkali lignin is dissolved in the alkaline solution to form a mixed solution, the pH value of the mixed solution can be adjusted to pH=1.5-3.5, and adjusted to such an acidic range, the industrial alkali lignin can be removed from the mixed solution fully precipitated. For example, the pH of the mixed liquid can be adjusted to 2.5. Of course, the pH value of the mixture can also be adjusted to other acidities. The specific embodiment is not limited thereto, as long as the industrial alkali lignin precipitate can be obtained.

Furthermore, when the agricultural and forestry biomass residues obtained after the hydrolysis treatment and the industrial alkali lignin obtained after the purification treatment are dried and pulverized, they can be pulverized into powders with a particle size of 90-350 mesh. For example, the agricultural and forestry biomass residues obtained after hydrolysis treatment and the industrial alkali lignin obtained after purification treatment can be pulverized into 300-mesh powder. Of course, it can also be pulverized into powders in other particle size ranges. The specific embodiment does not limit this. The powder with a particle size ranging from 90 to 350 meshes is used. Adding it to the adhesive can improve the pre-compression performance of the adhesive, reduce the internal stress of the adhesive layer after the adhesive is cured, and improve the bonding strength.

Further, the mass ratio of agricultural and forestry biomass residue powder and industrial alkali lignin powder can be 0-1:0-1, that is, these two powders can be mixed in any proportion, or these two powders and flour three Mixing between them in any proportion, or mixing one of the powders with the flour in any proportion, which is not limited in this specific embodiment. For example, the mass ratio of agricultural and forestry biomass residue powder and industrial alkali lignin powder can be 1:9, also can be 7:3 or 5:5, also can use agricultural and forestry biomass residue powder or industrial alkali lignin powder separately as As filler, agricultural and forestry biomass residue powder or industrial alkali lignin powder can also be mixed with flour as filler. Of course, when the agricultural and forestry biomass residue powder is mixed with industrial alkali lignin powder as filler, better use effect and lower cost can be achieved.

Further, the agricultural and forestry biomass residues may include: any one or more of corn stalks, rice straws, wheat straws, corncobs or bagasse. The industrial alkali lignin may include: any one or more of poplar alkaline kraft lignin, corn cob industrial alkali lignin or straw alkaline pulping lignin. Specifically, this embodiment does not limit the types of agricultural and forestry biomass residues and industrial alkali lignin selected.

By virtue of the above-mentioned technical scheme, the preparation method of a lignin-based filler provided in Example 1 of the present invention is to mix the agricultural and forestry biomass residue powder obtained after hydrolysis treatment with the industrial alkali lignin powder obtained after purification treatment, and prepare The method is simple and the preparation cost is low, and it can completely replace flour, the main food resource, as an additive for adhesives in the production of wood-based panels; at the same time, the presence of lignin in the filler can be used to supplement formaldehyde. The preparation method of the lignin-based filler provided by the embodiment of the invention can greatly reduce the formaldehyde emission of the wood-based panel. The invention expands the application range of agricultural and forestry biomass residues and industrial alkali lignin, and has excellent industrial application prospects.

As an application of the preparation method of a lignin-based filler provided in the above-mentioned embodiment 1, embodiment 2 of the present invention provides a lignin-based filler, which is prepared by the preparation method provided in the above-mentioned embodiment 1 .

By means of the above-mentioned technical solution, a lignin-based filler provided in Embodiment 2 of the present invention is mixed with the agricultural and forestry biomass residue powder obtained after hydrolysis treatment and the industrial alkali lignin powder obtained after purification treatment. The preparation method is simple and convenient. The preparation cost is low, and it can completely replace the main food resource of flour as an additive for the adhesive in the production of wood-based panels; at the same time, the presence of lignin in the filler can be used to supplement formaldehyde. Compared with the prior art, using the embodiment of the present invention The provided lignin-based filler can significantly reduce the formaldehyde emission of wood-based panels. The invention expands the application range of agricultural and forestry biomass residues and industrial alkali lignin, and has excellent industrial application prospects.

As an application of the lignin-based filler provided in the second embodiment above, the third embodiment of the present invention provides a urea-formaldehyde resin adhesive, including: urea-formaldehyde resin and filler. Wherein, the filler is the lignin-based filler provided in the second embodiment above.

Further, the mass ratio of the urea-formaldehyde resin and the filler in the urea-formaldehyde resin adhesive can be 100:20-30, for example, it can be prepared by adding 20 parts of filler or 30 parts of filler to 100 parts by mass of urea-formaldehyde resin Urea-formaldehyde resin adhesive. The specific embodiment does not limit this.

By means of the above-mentioned technical scheme, a urea-formaldehyde resin adhesive provided in Example 3 of the present invention mixes the agricultural and forestry biomass residue powder obtained after hydrolysis treatment with the industrial alkali lignin powder obtained after purification treatment, and its preparation method is simple 1. The preparation cost is low, and it can completely replace flour, the main food resource, as an additive for adhesives in wood-based panel production; at the same time, the presence of lignin in fillers can be used to supplement formaldehyde. Compared with the prior art, using the present invention The urea-formaldehyde resin adhesive provided by the example can greatly reduce the formaldehyde emission of wood-based panels. The invention expands the application range of agricultural and forestry biomass residues and industrial alkali lignin, and has excellent industrial application prospects.

As an application of the urea-formaldehyde resin adhesive provided in the above-mentioned embodiment three, embodiment four of the present invention provides a wood-based panel, which contains the urea-formaldehyde resin adhesive provided in the above-mentioned embodiment three.

By virtue of the above-mentioned technical scheme, a urea-formaldehyde resin adhesive provided in Example 4 of the present invention mixes the agricultural and forestry biomass residue powder obtained after hydrolysis treatment with the industrial alkali lignin powder obtained after purification treatment, and its preparation method is simple 1. The preparation cost is low, and it can completely replace flour, the main food resource, as an additive for adhesives in wood-based panel production; at the same time, the presence of lignin in fillers can be used to supplement formaldehyde. Compared with the prior art, using the present invention The wood-based panels provided by the example can greatly reduce the amount of formaldehyde released. The invention expands the application range of agricultural and forestry biomass residues and industrial alkali lignin, and has excellent industrial application prospects.

In order to more clearly show the effect of the lignin-based filler provided by the examples of the present invention, two comparative examples (comparative example one and comparative example two) and five examples (embodiment five, example six, example two) are provided below Seven, embodiment eight and embodiment nine) compare.

The urea-formaldehyde resins adopted in the above-mentioned comparative examples and examples are commercially available E1 grade common urea-formaldehyde resins, and the performance of the urea-formaldehyde resins is as follows:

All comparative examples and examples adopt 40*40*0.17cm eucalyptus veneer (moisture content 10-15%), veneer glue amount is 316g/m ² (both sides), after forming the billet, put it aside Time closed and aged for 1 hour, pre-pressed for 1 hour, pre-pressed pressure 2-3 MPa, hot-pressed temperature 120°C, hot-pressed pressure 1 MPa, hot-pressed time 1.5 min/mm. Bonding strength (Class II) and formaldehyde emission are tested according to the relevant standards in GB/T 17657-2013.

For the convenience of comparison, two flours are used as comparative examples of fillers, wherein the first comparative example adds a curing agent ammonium chloride, and the second comparative example does not add a curing agent. All do not add solidifying agent in embodiment five, embodiment six, embodiment seven, embodiment eight and embodiment nine, and add the example that the filler that the present invention is prepared is mixed with flour in the implementation example.

Comparative example one

Mix 100 parts by mass of urea-formaldehyde resin, 1 part of ammonium chloride and 25 parts of flour evenly, apply glue to the core board by roller coating, assemble the blank and leave it for 1 hour before hot pressing.

Comparative example two

Mix 100 parts by mass of urea-formaldehyde resin and 25 parts of flour evenly, apply glue to the core board by roller coating, and heat press after closing and placing the blank.

Embodiment five

1. Preparation of filler

(1) After crushing corn stalks to 1cm-sized particles, mix them with sulfuric acid solution with a mass percent concentration of 0.5% at a solid-to-liquid ratio of 1:5, react at 140°C and 0.5MPa pressure for 1.5h, and then hydrolyze the The corn stover hydrolyzed solids were dried and crushed to 200 mesh.

(2) After the corncob industrial alkali lignin is dissolved in a system with pH=10.5, the pH thereof is adjusted to 2, and the obtained acid-analyzed corncob industrial alkali lignin solid is dried and crushed to 200 mesh.

(3) Fully mix 50 parts by mass of hydrolyzed corn stalk powder and 50 parts of purified corncob industrial alkali lignin powder to obtain a lignin-based natural polymer urea-formaldehyde resin filler.

2. Adhesive preparation and plywood preparation

Set up three glue mixing schemes: (1) mix 100 parts by mass of urea-formaldehyde resin with 30 parts of lignin-based natural polymer urea-formaldehyde resin filler; (2) mix 100 parts by mass of urea-formaldehyde resin, 25 parts by mass lignin-based natural polymer urea-formaldehyde resin filler, and 5 parts of flour are uniformly mixed; (3) 100 parts by mass of urea-formaldehyde resin, 15 parts of lignin-based natural polymer urea-formaldehyde resin filler and 15 parts of flour are mixed uniformly. After the glue is adjusted, the glue is applied to the core board by roller coating, and it is pre-pressed according to the predetermined conditions and then hot-pressed. The test results of the bonding strength and formaldehyde emission of plywood are shown in Table 1 and Table 2.

Embodiment six

1. Preparation of filler

(1) Wheat straw is crushed to 2 cm in size, mixed with hydrochloric acid solution with a mass percentage concentration of 2% at a solid-to-liquid ratio of 1:10, reacted for 3 hours at 140°C and 0.7 MPa pressure, and then the hydrolyzed wheat Straw solids were dried and crushed to 350 mesh.

(2) After dissolving poplar basic kraft lignin in a system with pH=11.5, adjust its pH to 2.5, and dry and pulverize the obtained acid-analyzed poplar basic kraft lignin solid to 350 mesh.

(3) Fully mix 75 parts by mass of hydrolyzed wheat straw powder and 25 parts of purified poplar alkaline sulfate lignin powder to obtain a lignin-based natural polymer urea-formaldehyde resin filler.

2. Adhesive preparation and plywood preparation

Set up three glue mixing schemes: (1) mix 100 parts by mass of urea-formaldehyde resin with 30 parts of lignin-based natural polymer urea-formaldehyde resin filler; (2) mix 100 parts by mass of urea-formaldehyde resin, 25 parts by mass lignin-based natural polymer urea-formaldehyde resin filler, and 5 parts of flour are uniformly mixed; (3) 100 parts by mass of urea-formaldehyde resin, 15 parts of lignin-based natural polymer urea-formaldehyde resin filler and 15 parts of flour are mixed uniformly. After the glue is adjusted, the glue is applied to the core board by roller coating, and it is pre-pressed according to the predetermined conditions and then hot-pressed. The test results of the bonding strength and formaldehyde emission of plywood are shown in Table 1 and Table 2.

Embodiment seven

1. Preparation of filler

(1) Bagasse is pulverized to particles of 2 cm in size and mixed with water with a catalyst mass percentage concentration of 0% at a solid-to-liquid ratio of 1:10, reacted for 2.5 hours at 180° C. and 1.8 MPa pressure, and then hydrolyzed the Bagasse solids were dried and crushed to 350 mesh.

(2) After dissolving lignin from straw alkaline pulping in a system with pH=11, adjust its pH to 3.5, and dry and pulverize the obtained acid-analyzed straw alkaline pulping lignin solid to 150 mesh.

(3) Fully mix 95 parts by mass of hydrolyzed bagasse powder and 5 parts of purified rice straw alkaline pulping soda lignin powder to obtain a lignin-based natural polymer urea-formaldehyde resin filler.

2. Adhesive preparation and plywood preparation

Set up three glue mixing schemes: (1) mix 100 parts by mass of urea-formaldehyde resin with 30 parts of lignin-based natural polymer urea-formaldehyde resin filler; (2) mix 100 parts by mass of urea-formaldehyde resin, 25 parts by mass lignin-based natural polymer urea-formaldehyde resin filler, and 5 parts of flour are uniformly mixed; (3) 100 parts by mass of urea-formaldehyde resin, 15 parts of lignin-based natural polymer urea-formaldehyde resin filler and 15 parts of flour are mixed uniformly. After the glue is adjusted, the glue is applied to the core board by roller coating, and it is pre-pressed according to the predetermined conditions and then hot-pressed. The test results of the bonding strength and formaldehyde emission of plywood are shown in Table 1 and Table 2.

Embodiment eight

1. Preparation of filler

(1) Rice straw is crushed to 1 cm in size and mixed with 6% acetic acid solution at a solid-to-liquid ratio of 1:5, reacted at 170°C and 0.8 MPa for 1 hour, and then hydrolyzed the treated rice straw Straw solids were dried and crushed to 90 mesh.

(2) After the corncob industrial alkali lignin is dissolved in a system with pH=11, the pH thereof is adjusted to 2, and the obtained acid-analyzed corncob industrial alkali lignin solid is dried and crushed to 350 mesh.

(3) Fully mix 25 parts by mass of hydrolyzed rice straw powder and 75 parts of purified corncob alkali lignin powder to obtain a lignin-based natural polymer urea-formaldehyde resin filler.

2. Adhesive preparation and plywood preparation

Set up three glue mixing schemes: (1) mix 100 parts by mass of urea-formaldehyde resin with 30 parts of lignin-based natural polymer urea-formaldehyde resin filler; (2) mix 100 parts by mass of urea-formaldehyde resin, 25 parts by mass lignin-based natural polymer urea-formaldehyde resin filler, and 5 parts of flour are uniformly mixed; (3) 100 parts by mass of urea-formaldehyde resin, 15 parts of lignin-based natural polymer urea-formaldehyde resin filler and 15 parts of flour are mixed uniformly. After the glue is adjusted, the glue is applied to the core board by roller coating, and it is pre-pressed according to the predetermined conditions and then hot-pressed. The test results of the bonding strength and formaldehyde emission of plywood are shown in Table 1 and Table 2.

Embodiment nine

1. Preparation of filler

(1) After corncobs are crushed to 1cm-sized particles, they are mixed with a sulfuric acid solution with a mass percentage concentration of 1% at a solid-to-liquid ratio of 1:5, and reacted for 1.5h at 140°C under a pressure of 0.5MPa, and then the processed agricultural and forestry The biomass residue solid matter was dried and crushed to 90 mesh.

(2) After the corncob industrial alkali lignin is dissolved in a system with pH=10.5, the pH thereof is adjusted to 2, and the obtained acid-analyzed corncob industrial alkali lignin solid is dried and crushed to 350 mesh.

(3) Fully mix 5 parts by mass of hydrolyzed corncob powder and 95 parts of purified corncob alkali lignin powder to obtain a lignin-based natural polymer urea-formaldehyde resin filler.

2. Adhesive preparation and plywood preparation

Set up two glue mixing schemes: (1) mix 100 parts by mass of urea-formaldehyde resin with 30 parts of lignin-based natural polymer urea-formaldehyde resin filler; (2) mix 100 parts by mass of urea-formaldehyde resin, 25 parts by mass The lignin-based natural polymer urea-formaldehyde resin filler is mixed evenly. After the glue is adjusted, the glue is applied to the core board by roller coating, and it is pre-pressed according to the predetermined conditions and then hot-pressed. The test results of the bonding strength and formaldehyde emission of plywood are shown in Table 1 and Table 2.

Table 1 Plywood bonding strength

Table 2 Formaldehyde emission of plywood

From the above, it can be seen that Comparative Example 1 provides a mixture of flour and a curing agent as a filler; Comparative Example 2 provides only flour as a filler.

According to the preparation method of a lignin-based filler provided in Example 1,

Example 5 provides a lignin-based natural polymer urea-formaldehyde resin filler formed by mixing 50 parts by mass of hydrolyzed corn stalk powder and 50 parts of purified corncob industrial alkali lignin powder;

Example 6 provides a lignin-based natural polymer urea-formaldehyde resin filler formed by mixing 75 parts by mass of hydrolyzed wheat straw powder and 25 parts of purified poplar alkaline kraft lignin powder;

Example 7 provides a lignin-based natural high molecular weight urea-formaldehyde resin filler formed by mixing 95 parts by mass of hydrolyzed bagasse powder and 5 parts of purified straw alkaline pulping alkali lignin powder;

Embodiment 8 provides a lignin-based natural polymer urea-formaldehyde resin filler formed by mixing 25 parts by mass of hydrolyzed rice straw powder and 75 parts of purified corncob alkali lignin powder;

Example 9 provides a lignin-based natural polymer urea-formaldehyde resin filler formed by mixing 5 parts by mass of hydrolyzed corncob powder and 95 parts by mass of purified corncob alkali lignin powder.

Described each comparative example and embodiment are under the same condition, promptly used urea formaldehyde resin is identical, all adopts the eucalyptus veneer (moisture content 10～15%) of 40*40*0.17cm, veneer glue amount is uniform It is 316g/m2 (double-sided), after billet assembly, the aging time is closed and aging for 1h, pre-pressing for 1h, pre-pressing pressure 2-3MPa, hot-pressing temperature 120°C, hot-pressing pressure 1MPa, hot-pressing time 1.5min/mm. Through the adhesives formed by the fillers provided in each example and the urea-formaldehyde resin used, boards were made with these adhesives, and the bonding strength (Class II) and formaldehyde emission were tested according to the relevant standards in GB/T 17657-2013.

It can be seen from Table 1 and Table 2 that

The plywood made of flour and curing agent as filler provided in Comparative Example 1 has a bonding strength of 0.91 MPa and a formaldehyde emission of 0.84 mg/L.

The bonding strength of the plywood made of flour as a filler adhesive provided in Comparative Example 2 was 0.62 MPa, and the formaldehyde emission was 1.81 mg/L.

Example 5 provides the adhesive formed with urea-formaldehyde resin, filler and flour in three different proportions. The bonding strength of the plywood formed by it is respectively: 1.11MPa, 1.05MPa, 0.94MPa, and the formaldehyde emission is respectively: 0.52 mg/L, 0.52mg/L, 0.77mg/L.

As can be seen from the above, the bonding strength 1.11MPa, 1.05MPa, and 0.94MPa of plywood in embodiment five are all greater than the bonding strength 0.91MPa of plywood in comparative example one and the bonding strength 0.62MPa of plywood in comparative example two; The formaldehyde emission of 0.52mg/L, 0.52mg/L, and 0.77mg/L is less than the formaldehyde emission of 0.84mg/L of plywood in comparative example 1 and 1.81mg/L of formaldehyde emission of plywood in comparative example 2.

Example 6 provides the adhesive formed with urea-formaldehyde resin, filler and flour in three different proportions, the bonding strength of the plywood formed by it is respectively: 1.08MPa, 1.11MPa, 1.01MPa, and the formaldehyde emission is respectively: 0.36 mg/L, 0.44mg/L, 0.61mg/L.

As can be seen from above, the bonding strength 1.08MPa, 1.11MPa, and 1.01MPa of plywood in embodiment six are all greater than the bonding strength 0.91MPa of plywood in comparative example one and the bonding strength 0.62MPa of plywood in comparative example two; The formaldehyde emission of 0.36mg/L, 0.44mg/L, and 0.61mg/L is less than the formaldehyde emission of 0.84mg/L of plywood in comparative example 1 and the formaldehyde emission of 1.81mg/L of plywood in comparative example 2.

Example 7 provides the adhesive formed with urea-formaldehyde resin, filler and flour in three different proportions. The bonding strength of the plywood formed by it is respectively: 1.01MPa, 0.99MPa, 0.97MPa, and the formaldehyde emission is respectively: 0.47 mg/L, 0.51mg/L, 0.54mg/L.

As can be seen from above, the bonding strength 1.01MPa, 0.99MPa, and 0.97MPa of plywood in embodiment seven are all greater than the bonding strength 0.91MPa of plywood in comparative example one and the bonding strength 0.62MPa of plywood in comparative example two; The formaldehyde emission of 0.47mg/L, 0.51mg/L, and 0.54mg/L is less than the formaldehyde emission of 0.84mg/L of plywood in comparative example 1 and the formaldehyde emission of 1.81mg/L of plywood in comparative example 2.

Example 8 provides the adhesive formed with urea-formaldehyde resin, filler and flour in three different proportions. The bonding strength of the plywood formed by it is respectively: 0.99MPa, 0.96MPa, 0.97MPa, and the formaldehyde emission is respectively: 0.65 mg/L, 0.72mg/L, 0.84mg/L.

As can be seen from above, the bonding strength 0.99MPa, 0.96MPa, and 0.97MPa of plywood in embodiment eight are all greater than the bonding strength 0.91MPa of plywood in comparative example one and the bonding strength 0.62MPa of plywood in comparative example two; Formaldehyde emission 0.65mg/L, 0.72mg/L, 0.84mg/L are all less than (one example is equal to) the formaldehyde emission 0.84mg/L of plywood in comparative example one and the formaldehyde emission 1.81mg/L of plywood in comparative example two L.

Example 9 provides an adhesive formed of urea-formaldehyde resin, filler and flour in two different proportions. The bonding strength of the plywood formed by it is: 1.02MPa and 1.13MPa respectively, and the formaldehyde emission is respectively: 0.40mg/L , 0.78mg/L.

As can be seen from the above, the bonding strength 1.02MPa and 1.13MPa of plywood in embodiment nine are all greater than the bonding strength 0.91MPa of plywood in comparative example one and the bonding strength 0.62MPa of plywood in comparative example two; the formaldehyde emission of plywood in embodiment nine Both 0.40mg/L and 0.78mg/L are less than the formaldehyde emission of 0.84mg/L of plywood in comparative example 1 and 1.81mg/L of formaldehyde emission of plywood in comparative example 2.

From the data provided in Table 1 and Table 2, it can be seen that whether the filler provided by the embodiment of the present invention is used alone or mixed with flour as a filler, the adhesive formed by mixing with flour as a filler or flour and a curing agent as a filler Compared with the formed adhesive, the plywood made of it has stronger bonding strength and lower formaldehyde emission.

It can be seen from this that a lignin-based filler provided by the embodiment of the present invention can be used to replace flour as an adhesive filler. formaldehyde emission. The filler obtained in the embodiment of the present invention can completely replace flour as a high-performance urea-formaldehyde resin adhesive filler, and can also be mixed with flour in any proportion.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this professional technology Personnel, without departing from the scope of the technical solution of the present invention, when the above-mentioned technical content can be used to make some changes or be modified into equivalent embodiments of equivalent changes, but if it does not depart from the content of the technical solution of the present invention, according to the technical essence of the present invention Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solution of the present invention.

Claims (14)

1. a preparation method for lignin-base filler, is characterized in that, comprising:

A, be hydrolyzed agricultural-forestry biomass residuum process, comprises as step:

A1, described agricultural-forestry biomass residuum and aqueous catalyst solution are mixed, described aqueous catalyst solution is any one or several acidic solutions of sulphuric acid soln, hydrochloric acid soln or acetum;

A2, the agricultural-forestry biomass residuum after mixed and aqueous catalyst solution being hydrolyzed processes;

A3, to pulverize after the described agricultural-forestry biomass residuum drying after hydrolysis treatment, obtain agricultural-forestry biomass residuum powder;

B, industrial soda xylogen is carried out purification process, comprises as step:

B1, described industrial soda xylogen to be dissolved in basic solution;

B2, the pH value of mixed solution obtained after dissolving is adjusted to acidity, separates out industrial soda lignin deposit thing;

B3, to pulverize after the industrial soda lignin deposit thing drying of precipitation, obtain the industrial soda xylogen powder after purifying;

C, described agricultural-forestry biomass residuum powder and described industrial soda xylogen powder to be mixed, obtained described lignin-base filler.

2. preparation method according to claim 1, is characterized in that, before A, also comprises:

Described agricultural-forestry biomass residuum is pulverized, obtains the agricultural-forestry biomass residuum that particle diameter is 1 ~ 2cm.

3. preparation method according to claim 1, is characterized in that, solid-liquid mass ratio when described agricultural-forestry biomass residuum and described aqueous catalyst solution carry out mixed is 1:5 ~ 10.

4. preparation method according to claim 1, is characterized in that,

In described steps A 2, the temperature of hydrolysis treatment is 120 ~ 200 DEG C, and pressure is 0.5 ~ 2.0MPa, and duration is 0.5 ~ 4.0h.

5. preparation method according to claim 1, is characterized in that, in described steps A 1,

The mass percent concentration of described aqueous catalyst solution is not more than 9%.

6. preparation method according to claim 1, is characterized in that, in described step B1,

Described basic solution is the NaOH solution of pH>10.5.

7. preparation method according to claim 1, is characterized in that, in described step B2,

The pH value of described mixed solution is adjusted to pH=1.5 ~ 3.5.

8. preparation method according to claim 1, is characterized in that, the particle diameter of described agricultural-forestry biomass residuum powder and described industrial soda xylogen powder is 90 ~ 350 orders.

9. preparation method according to claim 1, is characterized in that, in described C, the mass ratio described agricultural-forestry biomass residuum powder and described industrial soda xylogen powder mixed is 0 ~ 1:0 ~ 1.

10. preparation method according to claim 1, is characterized in that,

Described agricultural-forestry biomass residuum comprises: any one or several of maize straw, rice straw, wheat stalk, corn cob or bagasse;

Described industrial soda xylogen comprises: any one or several of poplar basic sulfatase method xylogen, corn cob industrial soda xylogen or straw alkaline process xylogen.

11. 1 kinds of lignin-base fillers, is characterized in that, the described lignin-base filler obtained by the preparation method described in any one claim of claim 1-10.

12. 1 kinds of urea-formaldehyde resin adhesives, is characterized in that, comprising:

Urea-formaldehyde resin and filler;

Described filler is lignin-base filler according to claim 11.

13. urea-formaldehyde resin adhesives according to claim 12, is characterized in that, the mass ratio of described urea-formaldehyde resin and described filler is 100:20 ~ 30.

14. 1 kinds of wood-based plates, is characterized in that, containing the urea-formaldehyde resin adhesive described in claim 12 or 13 in wood-based plate.