Two-component bio-based artificial board adhesive as well as preparation method and application thereof

Abstract

The invention discloses a two-component bio-based artificial board adhesive as well as a preparation method and application thereof, and the two-component bio-based artificial board adhesive is prepared from the following components in parts by mass: 40-70 parts of polyacrylate emulsion, 5-15 parts of full bio-based lignin powder, 5-15 parts of filler, 0.1-1 part of emulsifier and 3-5 parts of polyisocyanate. The prepared two-component bio-based artificial board adhesive does not contain formaldehyde, has strong adhesive strength and excellent heat resistance, has an active period as long as 40-90 minutes and a pot life of 20-50 minutes, and has good initial adhesion. In addition, the artificial board manufactured by using the adhesive shows excellent surface adhesive strength and water resistance. The method is suitable for the actual conditions that the automation level of artificial board production is uneven and the procedure arrangement is not compact enough in China, sufficient operation time is provided for manufacturers, and waste of adhesives can be effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to a two-component bio-based artificial board adhesive and a preparation method and application thereof. Background Art

[0002] In 2016, the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China conducted a quality spot check on wood-based panel products, and inspected three items including moisture content, bonding strength and formaldehyde emission of wood-based panel products. The main problems found were excessive formaldehyde emission and unqualified bonding strength. With economic development and social progress, people's awareness of green environmental protection and health and safety has significantly improved, and they are paying close attention to the formaldehyde emission problem in wood-based panels. The adhesives used in the production of wood-based panels are mainly urea-formaldehyde resins and phenolic resins, and free formaldehyde is produced during the synthesis process. These free formaldehydes may not only release harmful gases during use, but also affect the chemical stability and physical properties of the adhesive. In addition, its storage stability is affected by multiple conditions such as pH value and temperature. If the pH value decreases or the temperature is too high during storage, it may cause the resin to solidify early or its performance to deteriorate.

[0003] Isocyanate belongs to non-aldehyde adhesives. The new polyisocyanate PMDI itself does not contain formaldehyde. There is no artificial formaldehyde release in the manufactured board. It is green and environmentally friendly. It has high reactivity and can produce covalent bonds with many adhered materials with active hydrogen atoms on the surface. After curing, it contains bonds and groups with strong polarity such as carbamate and urea bonds, which are easy to produce secondary bonds with the substrate, so that the adhered substrates have higher bonding strength. Generally, the molecular weight of polyisocyanate compounds is small, which makes it easier to diffuse to the surface of the substrate and penetrate into the porous adhered substrate, thereby further improving the bonding performance. Common finishing adhesives on the market usually use emulsions with active hydrogen-containing water-based polymers, such as polyvinyl alcohol aqueous solution, polyvinyl acetate emulsion, acrylic emulsion and other water-based vinyl resins as the main agent, and add isocyanate as a curing agent to form a water-based polymer-isocyanate adhesive (API). However, the disadvantage of this type of adhesive is that the market price of isocyanate is usually high, generally 8 to 10 times that of urea-formaldehyde resin. Although the unit amount of isocyanate glue used is lower than that of urea-formaldehyde resin, the final cost of wood-based panel products is still high due to its high price. In some cases, the investment in glue even accounts for more than 50% of the product cost. In addition, the free isocyanate produced during the production process is a toxic waste gas, which not only affects the health of production workers, but also poses potential harm to the environment and consumers. It also requires additional protective measures and harmless treatment equipment, which also increases production costs.

[0004] In the modern papermaking industry, lignin is a by-product of the pulp and paper industry. If it is not fully utilized, it will become one of the main sources of pollution in the papermaking industry, causing serious environmental pollution and waste of resources. Treating these wastewaters is an important task in the field of environmental protection. Effectively treating lignin in paper production wastewater not only helps to improve the level of environmental protection, but also reduces the operating costs of enterprises. Therefore, the method of treating lignin is particularly critical. For this reason, we turn waste into treasure and extract lignin from it for use in wood-based panel adhesives. Lignin, as a complex organic polymer, forms an important structural material in plant cell walls, especially in wood and bark. It is a natural polymer compound widely present in nature. It has the characteristics of rigidity and non-rottenness, thanks to its unique chemical structure-cross-linked phenol polymers. It is precisely because of this structure that lignin can maintain remarkable stability at high temperatures. Studies have shown that lignin has excellent high temperature resistance and can usually remain stable at temperatures up to 250°C. Its decomposition temperature range is roughly between 230°C and 270°C, but the specific temperature will be affected by the type of wood and many other factors. This stability makes lignin an ideal choice for high temperature resistant applications, such as material manufacturing in high temperature environments, thermal insulation materials, and fields that need to withstand high temperature processes. The production cost of lignin is relatively low, and during the extraction and application process, lignin produces less pollution, which is beneficial to environmental protection. With the global emphasis on environmental protection and sustainable development, lignin, as a renewable and sustainable natural polymer compound, will receive more attention and favor from more industries, and the demand for lignin in the field of industrial materials will show a trend of diversified expansion.

[0005] Therefore, developing a two-component bio-based artificial board adhesive that can improve the existing shortcomings of existing artificial board adhesives such as high cost, high petroleum-based content, and formaldehyde, and achieving low preparation cost, good high temperature resistance, green environmental protection, and excellent storage stability has a very broad application market. Summary of the invention

[0006] The purpose of the present invention is to provide a two-component bio-based artificial board adhesive and a preparation method and application thereof in view of the deficiencies of the prior art.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a two-component bio-based wood-based panel adhesive, which is made of the following raw materials in parts by weight:

[0009]

[0010] Furthermore, the polyacrylate emulsion is a copolymer of methacrylic acid, methyl methacrylate, n-butyl acrylate and Solvay phosphate polymer emulsifier.

[0011] Furthermore, the polyacrylate emulsion has a solid content of 52-55%, a pH value of 7-8, and an average particle size of 250-450 nm.

[0012] Furthermore, the polyacrylate emulsion is prepared by the following method, in parts by mass:

[0013] (a.1) under a nitrogen atmosphere, 10 to 15 parts of methacrylic acid, 5 to 15 parts of methyl methacrylate, 5 to 15 parts of n-butyl acrylate, 0.1 to 1 part of methyl acetoacetate phosphate polymeric emulsifier, 0.1 to 3 parts of a persulfate initiator aqueous solution and 0.1 to 3 parts of a sodium bicarbonate buffer solution are mixed and reacted at 75 to 82° C. for 25 to 40 minutes to obtain a seed emulsion;

[0014] (a.2) 5 to 10 parts of methyl methacrylate, 5 to 15 parts of n-butyl acrylate, 3 to 15 parts of ethylene glycol acetoacetate, 0.1 to 1 part of silane coupling agent, 0.1 to 1 part of photoinitiator, 0.1 to 1 part of persulfate initiator aqueous solution, 0.1 to 1 part of Solvay phosphate polymer emulsifier and 1 to 3 parts of emulsifier aqueous solution are then mixed and added dropwise to the seed emulsion in 3 to 5 portions, followed by reaction at 75 to 82° C. for 3 to 4 hours, and then the pH value of the emulsion is adjusted to 7 to 8 to obtain a polyacrylate emulsion.

[0015] Furthermore, the fully biobased lignin powder is paper industry lignin, with a solid content of 40-45%, a pH value of 3-4, and is crushed into 800-1250 meshes by a grinder.

[0016] Furthermore, the filler is one or more of quartz powder, titanium dioxide, chromium oxide powder, talcum powder, kaolin, calcium carbonate, flour, and mica powder mixed in any proportion.

[0017] Furthermore, the polyisocyanate is a mixture of one or more of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate in any proportion.

[0018] Furthermore, the emulsifier is one or more of X-405, BCH40, and OP-40 with narrow EO addition number distribution and narrow molecular weight distribution, mixed in any proportion.

[0019] In a second aspect, the present invention further provides a method for preparing a two-component bio-based wood-based panel adhesive, comprising the following steps:

[0020] (1) adding 0.1 to 1 parts by weight of an emulsifier, 5 to 15 parts by weight of a filler and 5 to 15 parts by weight of fully biobased lignin powder to 40 to 70 parts by weight of a polyacrylate emulsion, and uniformly stirring until the surface of the emulsion is smooth and fine, to obtain an emulsion;

[0021] (2) Then, 3 to 5 parts by weight of polyisocyanate are added to the emulsion prepared in step (1), and the mixture is mixed to obtain a two-component bio-based wood-based panel adhesive.

[0022] In a third aspect, the present invention further provides an application of a two-component bio-based artificial board adhesive, wherein the two-component bio-based artificial board adhesive is applied to the production of artificial boards.

[0023] The beneficial effects of the present invention are as follows: the two-component bio-based artificial board adhesive prepared by the formula composition and process of the present invention has high bonding strength, an extended application period of 20 to 50 minutes, an active period of 40 to 90 minutes, and is suitable for the current situation in my country where the degree of production automation is low and the arrangement of various processes is not compact, and sufficient operation time can be reserved for artificial board manufacturers; it has excellent high temperature resistance, low preparation cost, and excellent storage stability, water resistance and environmental protection, and meets the China Environmental Labeling Ten-Ring Certification Standard. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention is further described in detail in combination with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than all 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.

[0025] The present invention provides a two-component bio-based artificial board adhesive, which is made of the following raw materials in parts by weight:

[0026]

[0027]

[0028] The present invention also provides a method for preparing a two-component bio-based artificial board adhesive, which comprises the following steps, calculated by weight:

[0029] (1) preparing a polyacrylate emulsion: under a protective nitrogen atmosphere, mixing 10 to 15 parts of methacrylic acid, 5 to 15 parts of methyl methacrylate, 5 to 15 parts of n-butyl acrylate, 0.1 to 1 part of methyl acetoacetate phosphate polymeric emulsifier, 0.1 to 3 parts of a persulfate initiator aqueous solution and 0.1 to 3 parts of a sodium bicarbonate buffer solution, and reacting the mixture at 75 to 82° C. for 25 to 40 minutes to obtain a seed emulsion; then mixing 5 to 10 parts of methyl methacrylate, 5 to 15 parts of n-butyl acrylate, 3 to 15 parts of ethylene glycol acetoacetate methacrylate, 0.1 to 1 part of silane coupling agent, 0.1 to 1 part of photoinitiator, 0.1 to 1 part of persulfate initiator aqueous solution, 0.1 to 1 part of Solvay phosphate polymer emulsifier and 1 to 3 parts of emulsifier aqueous solution are mixed, and then added dropwise to the seed emulsion in 3 to 5 parts, and then reacted at 75 to 82° C. for 3 to 4 hours, and then the pH value of the emulsion is adjusted to 7 to 8 to obtain a polyacrylate emulsion.

[0030] (2) adding 0.1 to 1 parts by weight of an emulsifier, 5 to 15 parts by weight of a filler and 5 to 15 parts by weight of fully biobased lignin powder to the polyacrylate emulsion prepared in step (1), and uniformly stirring until the surface of the emulsion is smooth and fine, to obtain an emulsion;

[0031] (3) Then, 3 to 5 parts by weight of polyisocyanate are added to the emulsion prepared in step (2), and the mixture is mixed to obtain a two-component bio-based wood-based panel adhesive.

[0032] The polyacrylate emulsion adopts Solvay phosphate as a polymerized emulsifier. The polymerized polyacrylate emulsion has excellent water resistance and light permeability of the coating film, has the effect of improving the adhesion of the substrate, is more efficient in the polymerization process, can form a large-particle emulsion, but is not prone to a gel-free system, and can react with isocyanate to achieve a longer active period, which is beneficial to the mixing and use of glue; and the phosphate emulsifier does not contain APEO, which meets international environmental protection requirements.

[0033] The fully biobased lignin powder is used as paper industry lignin, and the phenolic polymer structure of lignin cross-links enables lignin to maintain significant stability at high temperatures, and lignin is a three-dimensional network structure biopolymer formed by phenylpropane units interconnected by ether bonds and carbon-carbon bonds, and under high temperature conditions, the active functional groups (such as hydroxyl, carboxyl, etc.) in its molecules will undergo condensation, esterification and other reactions to form new chemical bonds, and the formation of these chemical bonds will connect the lignin molecules together to form a cross-linked structure, which not only gives lignin excellent mechanical strength, but also makes the lignin material have the characteristics of thermosetting resins, and after curing, it can withstand higher temperatures without deformation, and has excellent thermal stability. In addition, lignin contains abundant active groups such as aromatic ring structures, aliphatic and aromatic hydroxyl groups and quinone groups, and these groups also provide support for its chemical stability and high temperature resistance.

[0034] The emulsifier is one or more of X-405, BCH40, and OP-40 with narrow EO addition number distribution and narrow molecular weight distribution, mixed in any proportion. Dow water-soluble nonionic surfactant octylphenol polyoxyethylene ether X-405 is used, and its narrow distribution and high EO number can significantly reduce the surface tension of the adhesive to the substrate, making it easier for the adhesive to wet the surface of the substrate. It has excellent penetration properties that allow the adhesive to penetrate into the interior of the substrate, effectively improving the bonding strength of the adhesive; Solvay fatty alcohol polyoxyethylene ether surfactant BCH40 is selected, which has the characteristic of rapid migration to the interface, and the surface modification performance can be used to reduce surface tension, increase absorbency and permeability, and has excellent wetting, emulsification and penetration properties. The emulsifier molecules form a dense interfacial film at the oil-water interface, which has a protective effect on the dispersed phase droplets, preventing them from colliding with each other in Brownian motion and causing aggregation. The combination of ionic emulsifier and nonionic emulsifier can utilize the electrostatic repulsion of ionic emulsifier and the steric hindrance effect of nonionic emulsifier, thereby improving the stability of polymer emulsion while ensuring the polymerization speed. Through the combined action of multiple mechanisms such as reducing interfacial tension, forming interfacial film, generating electrostatic repulsion and steric hindrance, the emulsion can be effectively prevented from breaking and the stability of the emulsion can be maintained.

[0035] The polyisocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate or polymethylene polyphenyl polyisocyanate. It has high reactivity and can generate covalent bonds with the surface of the adhered material containing active hydrogen atoms. After curing, it contains bonds and groups with strong polarity such as carbamate and urea bonds, which can generate secondary bonds with the substrate, so that the adhered substrates have higher bonding strength. In addition, the molecular weight of this type of compound is usually small, which can better diffuse to the surface of the substrate and penetrate into the porous adhered substrate, thereby further improving the adhesive performance.

[0036] In the present invention: the applicable period of the adhesive specifically refers to the application of the adhesive on the veneer, placing it in a constant temperature and humidity oven (such as: 35°C, relative humidity 60%), taking it out after 5-30 minutes, covering the surface of the veneer with a thick layer of wood powder, gently pressing and pouring off the excess wood powder, observing whether the film on the veneer is covered with a layer of wood powder, and recording the time when the veneer is placed in the oven when there is no obvious wood powder on the film. The applicable period. The active period specifically refers to the increase in the viscosity of the system under the constant temperature and humidity conditions of 35°C and 60% relative humidity after the adhesive is prepared, and recording the time when the viscosity of the system increases rapidly at a certain moment and the glue loses fluidity. In some specific embodiments, the applicable period of the adhesive reaches 20 to 50 minutes, and the active period is 40 to 90 minutes.

[0037] The present invention also provides a two-component bio-based artificial board adhesive which can be applied to the production of artificial boards.

[0038] Example 1

[0039] A method for preparing a two-component bio-based wood-based panel adhesive comprises the following steps, measured in parts by weight:

[0040] (1) Add 0.2 parts of an emulsifier, 5 parts of calcium carbonate and 10 parts of fully biobased lignin powder to 70 parts of a polyacrylate emulsion, and stir evenly until the surface of the emulsion is smooth and fine to obtain an emulsion.

[0041] (2) Add 5 parts of polyisocyanate to the emulsion prepared in step (1), and mix to obtain a two-component bio-based wood-based panel adhesive.

[0042] Example 2

[0043] A method for preparing a two-component bio-based wood-based panel adhesive comprises the following steps, measured in parts by weight:

[0044] (1) Add 0.4 parts of an emulsifier, 5 parts of calcium carbonate and 10 parts of fully biobased lignin powder to 50 parts of a polyacrylate emulsion, and stir evenly until the surface of the emulsion is smooth and fine to obtain an emulsion.

[0045] (2) Add 3 parts of polyisocyanate to the emulsion prepared in step (1), and mix to obtain a two-component bio-based wood-based panel adhesive.

[0046] Example 3

[0047] A method for preparing a two-component bio-based wood-based panel adhesive comprises the following steps, measured in parts by weight:

[0048] (1) Add 0.6 parts of an emulsifier, 10 parts of calcium carbonate and 15 parts of fully biobased lignin powder to 50 parts of a polyacrylate emulsion, and stir evenly until the surface of the emulsion is smooth and fine to obtain an emulsion.

[0049] (2) Add 3 parts of polyisocyanate to the emulsion prepared in step (1), and mix to obtain a two-component bio-based wood-based panel adhesive.

[0050] Example 4

[0051] A method for preparing a two-component bio-based wood-based panel adhesive comprises the following steps, measured in parts by weight:

[0052] (1) adding 0.8 parts of an emulsifier, 10 parts of calcium carbonate and 15 parts of fully biobased lignin powder to 70 parts of a polyacrylate emulsion, and uniformly stirring until the surface of the emulsion is smooth and fine, to obtain an emulsion;

[0053] (2) Add 5 parts of polyisocyanate to the emulsion prepared in step (1), and mix to obtain a two-component bio-based wood-based panel adhesive.

[0054] Comparative Example 5

[0055] Commercially available urea-formaldehyde resin adhesive for artificial boards.

[0056] Comparative Example 6

[0057] Commercially available phenolic resin artificial board adhesive.

[0058] The two-component bio-based artificial board adhesive prepared in the above embodiments 1-4, the commercially available urea-formaldehyde resin artificial board adhesive, and the commercially available urea-formaldehyde resin artificial board adhesive were respectively infiltrated on single boards, and then placed under constant temperature and humidity conditions of 35°C and relative humidity of 60% for applicability test, and the glue activity period was tested under these conditions; the two-component bio-based artificial board adhesive prepared in the above embodiments 1-4, the commercially available urea-formaldehyde resin artificial board adhesive, and the commercially available urea-formaldehyde resin artificial board adhesive were respectively infiltrated on artificial boards, and the bonding strength and formaldehyde emission were tested.

[0059] The embodiments and comparative examples of the present invention were tested according to relevant test methods, and the heat resistance, bonding strength and formaldehyde emission were measured according to GBT 17657-2013 Test Methods for Physical and Chemical Properties of Artificial Boards and Facing Artificial Boards and GB / T 32368-2015 Test Methods for High Temperature and High Humidity Aging of Adhesive Tapes, and the viscosity was measured according to GB / T2794-2013 Determination of Adhesive Viscosity Single Cylinder Rotational Viscometer Method. The test results of the performance of the two-component bio-based artificial board adhesive are shown in Table 1. The test results of the high temperature resistance of the two-component bio-based artificial board adhesive are shown in Table 2.

[0060] Table 1: Performance test results of two-component bio-based wood-based panel adhesive

[0061]

[0062]

[0063] Table 2: Test results of high temperature resistance of two-component bio-based wood-based panel adhesive

[0064]

[0065] It can be seen from the test data in Table 1 and Table 2 that the two-component bio-based wood-based panel adhesive prepared by the present invention does not contain formaldehyde, has strong bonding strength and excellent heat resistance, and has a long active period. It is suitable for the actual situation in my country where the automation level of wood-based panel production is uneven and the process arrangement is not compact enough. It provides manufacturers with sufficient operation time and can effectively reduce the waste of adhesives. It also has excellent storage stability, water resistance and environmental protection, and meets the China Environmental Labeling Ten-Ring Certification Standard.

[0066] The active period is as long as 40 to 90 minutes, the applicable period is 20 to 50 minutes, and it has good initial adhesion. In addition, the wood-based panels manufactured using this adhesive show excellent surface bonding strength and water resistance. It is suitable for the actual situation in my country where the automation level of wood-based panel production is uneven and the process arrangement is not compact enough, providing manufacturers with sufficient operating time and effectively reducing the waste of adhesives.

[0067] 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 principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A two-component bio-based wood-based panel adhesive, characterized in that: Made from the following raw materials in parts by weight:

2. A two-component bio-based wood-based panel adhesive according to claim 1, characterized in that: The polyacrylate emulsion is a copolymer of methacrylic acid, methyl methacrylate, n-butyl acrylate and Solvay phosphate polymer emulsifier.

3. A two-component bio-based wood-based panel adhesive according to claim 2, characterized in that: The polyacrylate emulsion has a solid content of 52-55%, a pH value of 7-8, and an average particle size of 250-450 nm.

4. A two-component bio-based wood-based panel adhesive according to claim 3, characterized in that: The polyacrylate emulsion is prepared by the following method, in parts by mass: (a.1) under a nitrogen atmosphere, 10 to 15 parts of methacrylic acid, 5 to 15 parts of methyl methacrylate, 5 to 15 parts of n-butyl acrylate, 0.1 to 1 part of methyl acetoacetate phosphate polymeric emulsifier, 0.1 to 3 parts of a persulfate initiator aqueous solution and 0.1 to 3 parts of a sodium bicarbonate buffer solution are mixed and reacted at 75 to 82° C. for 25 to 40 minutes to obtain a seed emulsion; (a.2) 5 to 10 parts of methyl methacrylate, 5 to 15 parts of n-butyl acrylate, 3 to 15 parts of ethylene glycol acetoacetate, 0.1 to 1 part of silane coupling agent, 0.1 to 1 part of photoinitiator, 0.1 to 1 part of persulfate initiator aqueous solution, 0.1 to 1 part of Solvay phosphate polymer emulsifier and 1 to 3 parts of emulsifier aqueous solution are mixed, and then added dropwise to the seed emulsion in 3 to 5 portions, followed by reaction at 75 to 82° C. for 3 to 4 hours, and then the pH value of the emulsion is adjusted to 7 to 8 to obtain a polyacrylate emulsion.

5. The two-component bio-based wood-based panel adhesive according to claim 1, characterized in that: The fully biobased lignin powder is lignin from the papermaking industry, has a solid content of 40-45%, a pH value of 3-4, and is crushed into 800-1250 meshes by a grinder.

6. The two-component bio-based wood-based panel adhesive according to claim 1, characterized in that: The filler is one or more of quartz powder, titanium dioxide, chromium oxide powder, talcum powder, kaolin, calcium carbonate, flour and mica powder mixed in any proportion.

7. The two-component bio-based wood-based panel adhesive according to claim 1, characterized in that: The polyisocyanate is a mixture of one or more of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate in any proportion.

8. The two-component bio-based wood-based panel adhesive according to claim 1, characterized in that: The emulsifier is one or more of X-405, BCH40 and OP-40 with narrow EO addition number distribution and narrow molecular weight distribution, mixed in any proportion.

9. A method for preparing a two-component bio-based wood-based panel adhesive according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) adding 0.1 to 1 parts by weight of an emulsifier, 5 to 15 parts by weight of a filler and 5 to 15 parts by weight of fully biobased lignin powder to 40 to 70 parts by weight of a polyacrylate emulsion, and uniformly stirring until the surface of the emulsion is smooth and fine, to obtain an emulsion; (2) Then, 3 to 5 parts by weight of polyisocyanate are added to the emulsion prepared in step (1), and the mixture is mixed to obtain a two-component bio-based wood-based panel adhesive.

10. The use of a two-component bio-based wood-based panel adhesive according to any one of claims 1 to 8, characterized in that: The two-component bio-based artificial board adhesive is used in the production of artificial boards.

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