Preparation method and application of formaldehyde-free adhesive for artificial boards

Abstract

The present invention discloses a preparation method and application of formaldehyde-free glue for artificial boards, and relates to the technical field of adhesives. The method comprises the following steps: mixing a main monomer, a first initiator, and an emulsifier, and reacting at 20-40°C for 0.5-1h; adding a functional monomer and a second initiator to the above reaction system, and continuing to react at 40-75°C for 2-6h; adding a terminator to obtain a polymer emulsion after continuing to react the reaction system at 40-60°C for 0.5-1h; and uniformly mixing the polymer emulsion with a curing cross-linking agent to obtain formaldehyde-free glue. The method of the present invention adopts a three-stage polymerization reaction to prepare an olefin polymer emulsion, so that the residual monomer content in the polymer emulsion is as low as 5-100 PPM; the method of the present invention improves the properties of the polymer emulsion by introducing a functional monomer, so that it is more suitable as a wood adhesive; and then the polymer emulsion is compounded with a curing cross-linking agent and applied to an artificial board, so that an environmentally friendly and excellent performance board can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to a preparation method and application of formaldehyde-free adhesive for artificial boards. Background Art

[0002] Adhesives play a vital role in the wood industry. The amount of adhesives used has become an important indicator to measure the technical level of a country or region's wood industry. With the development of my country's national economy and the continuous improvement of people's living standards, the society's demand for wood and wood products will greatly increase. Therefore, the use of adhesives has also increased dramatically.

[0003] With the further implementation of my country's natural forest protection project, the number of small and medium-sized wood will increase. Therefore, the production of various wood-based panels using small and medium-sized wood, wood processing residues and forest felling residues will become the focus of my country's wood industry development. Therefore, my country's wood-based panel products must continuously improve quality and reduce costs in order to remain invincible in market competition. The quality level and market competitiveness of wood-based panel products depend to a large extent on the production level of adhesives. The quality of adhesives has an important impact on the product quality of wood-based panels. The cost of adhesives accounts for a large share of the entire production cost of wood-based panels. If the cost of adhesives cannot be reduced, the cost of wood-based panels cannot be reduced. Therefore, the development of wood-based panel adhesives is becoming more and more important.

[0004] At present, the main problems existing in my country's adhesive industry are manifested in the following aspects: (1) The high free formaldehyde content in adhesives leads to excessive formaldehyde release in wood-based panel products. Due to the widespread use of wood-based panel products in my country's interior decoration and furniture industries, this problem has directly become a social problem that affects human health and has created a very negative impression in all sectors of society. In addition, other harmful components in adhesives, such as phenol, have a significant impact on human health and the environment. If these problems are not properly resolved, they will have a serious impact on the sales of my country's wood-based panel products. (2) my country's adhesive production mostly depends on wood-based panel manufacturers, which produce and use them themselves. This small-scale agricultural production method is not conducive to the development of the adhesive industry. Most of my country's wood-based panel manufacturers are relatively small in scale and operate independently. Small factories rarely have the ability to seriously deal with adhesive production and quality issues. (3) The adhesive production process is backward, the quality is unstable, and the adaptability to raw materials and adhesive equipment is poor. Due to the inherent quality problems of the adhesive itself, in order to ensure the quality of wood-based panel products, it can only be solved by increasing the amount of adhesive. Excessive use of glue is the main reason why the production cost of wood-based panels cannot be reduced.

[0005] At present, my country's artificial board industry mainly uses urea-formaldehyde glue, phenol-formaldehyde glue, and melamine-formaldehyde glue because of their abundant raw material sources, simple synthesis process and low cost. From the name of the adhesive, it can be seen that these adhesives all contain "aldehyde-containing glue" with aldehyde structure, which will release "free formaldehyde" during the drying process. When artificial boards using these adhesives are used in interior decoration and furniture industries, the volatile aldehyde substances released will cause damage to the natural environment and human health, and directly become a social problem affecting human health.

[0006] With the pursuit of improved living conditions and the improvement of environmental awareness, some polyurethane adhesives and soy protein adhesives with zero formaldehyde emission have appeared on the market from the perspective of environmental protection. Although polyurethane adhesives have a fast curing speed, they are expensive and are easily affected by ambient temperature and humidity. Moreover, the too fast curing speed makes the application time of the colloid very short, and it is easy to adhere to the template and conveyor belt, which places high requirements on the production line, makes it difficult to control the amount of colloid, and increases the production cost. Soy protein adhesive is an adhesive prepared from soybeans. Although it is relatively cheap, it contains organic components such as starch and protein. The presence of these components makes the artificial board easily eroded by bacteria and mold in the air, resulting in plaque and mold growth, and its bonding strength, water resistance and weather resistance are also poor.

[0007] In summary, the present invention provides a preparation method and application of formaldehyde-free glue for artificial boards. The adhesive prepared by the method of the present invention does not contain aldehyde groups, and the artificial boards using this adhesive can achieve the effect of zero formaldehyde release; the above-mentioned formaldehyde-free glue introduces functional monomers during the preparation process, so that the formaldehyde-free glue has certain antibacterial and flame retardant effects; in addition, a three-stage polymerization method is adopted in the preparation of the formaldehyde-free glue to control extremely low monomer residues, so that the formaldehyde-free glue has no odor, and is an environmentally friendly adhesive with excellent comprehensive performance. Summary of the invention

[0008] In view of the deficiencies in the above prior art, the purpose of the present invention is to develop a preparation method and application of formaldehyde-free glue for artificial boards. The adhesive prepared by the method of the present invention does not contain aldehyde groups, and the artificial boards using this adhesive can achieve the effect of zero formaldehyde release; the above-mentioned formaldehyde-free glue introduces functional monomers during the preparation process, so that the formaldehyde-free glue has certain antibacterial and flame retardant effects; in addition, a three-stage polymerization method is adopted in the preparation of the formaldehyde-free glue to control extremely low monomer residues, so that the formaldehyde-free glue has no odor, and is an environmentally friendly adhesive with excellent comprehensive performance.

[0009] To achieve the above purpose, the specific technical solutions of the present invention are as follows:

[0010] A method for preparing formaldehyde-free adhesive for artificial boards comprises the following steps:

[0011] (1) Mixing a main monomer, a first initiator, an emulsifier and a solvent, and reacting them at 20-40° C. for 0.5-1 h; the main monomer is selected from two or more of ethylene, vinyl chloride, vinyl acetate and vinylidene chloride;

[0012] (2) adding a functional monomer and a second initiator to the reaction system in step (1), and continuing the reaction at 40-75° C. for 2-6 hours; the functional monomer includes but is not limited to: one or more of a compound containing a double bond and a hydroxyl group, a compound containing a double bond and a carboxyl group, a compound containing a double bond and an epoxy group, a compound containing a double bond siloxane, vinyl isobutyl ether, isobutoxymethyl acrylamide, and diacetone acrylamide;

[0013] (3) The reaction system in step (2) is reacted at 40-60° C. for 0.5-1 h, a terminator is added to obtain a polymer emulsion, and the polymer emulsion is used to prepare a formaldehyde-free adhesive.

[0014] Preferably, the compound containing a double bond and a hydroxyl group has the following structure:

[0015] ;

[0016] Among them, R is an alkyl group containing an acid anhydride group, a carboxyl group, an amino group, an imino group, an amide group, an alkoxysilyl group, a silanol group, a silyl ether group, a hydroxyl group, an epoxy group, a halogen group, a mercapto group, an episulfide group, or an unsaturated bond functional group.

[0017] Preferably, the compound containing a double bond and a carboxyl group has the following structure:

[0018] ;

[0019] Among them, R is an acid anhydride group, a carboxyl group, an amino group, an imino group, an alkoxysilyl group, a silanol group, a silyl ether group, a hydroxyl group, an epoxy group, a halogen group, a mercapto group, an episulfide group, and an alkyl group containing an unsaturated bond functional group.

[0020] Preferably, the compound containing a double bond and an epoxy group has the following structure:

[0021] ;

[0022] Among them, R is an acid anhydride group, a carboxyl group, an amino group, an imino group, an alkoxysilyl group, a silanol group, a silyl ether group, a hydroxyl group, an epoxy group, a halogen group, a mercapto group, an episulfide group, and an alkyl group containing an unsaturated bond functional group.

[0023] Preferably, the double bond siloxane-containing compound has the following structure:

[0024] ;

[0025] Among them, R1, R2, and R3 are respectively an alkyl group containing anhydride group, carboxyl group, amino group, imino group, alkoxysilyl group, silanol group, silyl ether group, hydroxyl group, epoxy group, halogen group, mercapto group, episulfide group, and unsaturated bond functional group.

[0026] Preferably, the mass ratio of the main monomer to the functional monomer is 1:(0.05-0.5).

[0027] Preferably, the polymer emulsion and the curing cross-linking agent are uniformly mixed to prepare the formaldehyde-free adhesive.

[0028] Preferably, the curing cross-linking agent is composed of one or more of the following: isocyanate containing isocyanate, adipic acid dihydrazide, melamine, trimethylol melamine, hexamethoxymethyl melamine, polyol compounds, organic amine compounds, organosilicon compounds containing double bonds, hydroxypropyl methylcellulose, and peroxide compounds.

[0029] More preferably, the polyol compound includes one of ethylene glycol, propylene glycol, butylene glycol and pentanediol.

[0030] Further preferably, the organic amine compound includes one of o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, o-chloroaniline, m-chloroaniline, p-chloroaniline, N,N-dimethylethanolamine, N,N-diethylethanolamine, triethylenediamine, diethylenetriamine, cyclohexyleneimine and polyethyleneimine.

[0031] Further preferably, the double bond-containing organosilicon compound includes one of vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, styryltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, glycidoxypropylvinyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane.

[0032] Preferably, the first initiator and the second initiator are azo initiators and / or peroxide initiators.

[0033] Preferably, the first initiator and the second initiator are used in an amount of 0.1% to 0.6% of the total monomer amount.

[0034] The total monomer amount is the sum of the masses of the main monomer and the functional monomer.

[0035] Preferably, the emulsifier is an anionic emulsifier and / or a nonionic emulsifier.

[0036] Preferably, the amount of the emulsifier used is 1%-8% of the total monomer amount.

[0037] Preferably, the terminator is sorbic acid.

[0038] Preferably, the amount of the terminator is 0.01%-0.03% of the total monomer amount.

[0039] The present invention also provides an application of the formaldehyde-free adhesive in artificial boards.

[0040] The weight average molecular weight of the polymer emulsion prepared by the method of the present invention is 1000-500000 Dalton, the viscosity is 500-20000 mPa·s, the glass transition temperature (Tg) is -50-70°C, and the solid content of the emulsion is controlled at 20-65%. The present invention adopts a three-stage polymerization reaction to prepare the olefin polymer emulsion, so that the polymer emulsion has excellent performance, and the content of the residual monomer of the polymer emulsion is as low as 5-100 PPM, and the extremely low monomer residue is controlled, so that the formaldehyde-free glue prepared by the present invention has no odor; the properties of the polymer emulsion are further improved by introducing functional monomers, making it more suitable as a wood adhesive; wherein, different monomer combinations and different proportions can be used to obtain emulsions with different properties. The present invention adopts emulsion polymerization to prepare polymer emulsion, the process is simple and mature, and the polymerization conditions are easy to control; the introduced functional monomer can adjust the performance of the adhesive to obtain an adhesive that meets the design requirements; the curing cross-linking agent of the present invention selects a compound with a reactive group, which can achieve self-crosslinking and / or intermolecular crosslinking, thereby achieving the purpose of drying and curing; different ratios between the polymer emulsion and the curing cross-linking agent can achieve different curing speeds, so the curing speed can be controlled by changing the ratio of the curing cross-linking agent to the emulsion, so that the adhesive meets the requirements of on-site production. The present invention uses the polymer emulsion and the curing cross-linking agent to compound and apply them to the artificial board to obtain a board with excellent performance.

[0041] Compared with the prior art, the present invention is beneficial in that:

[0042] (1) The formaldehyde-free adhesive prepared by the method of the present invention does not contain formaldehyde, has an extremely low residual content and is biodegradable, is environmentally friendly, and can be widely used;

[0043] (2) The method provided by the present invention is to first react the main monomer at low temperature for 0.5-1h, then introduce the functional monomer to react at a high temperature for 2-6h, and then cool down and continue to react for 0.5-1h to prepare a polymer emulsion. Compared with starch glue and protein glue that are easily corroded by bacteria and mold, the polymer emulsion prepared by the present invention has certain antibacterial and flame retardancy;

[0044] (3) Compared with the existing formaldehyde-free MDI (diphenylmethane diisocyanate) rigid adhesive, the formaldehyde-free adhesive of the present invention can change the properties and curing time of the adhesive by adjusting the monomer combination and the addition ratio of the curing cross-linking agent, so that the board has good flexibility and bendability, avoiding the problem of the board being prone to cracking during processing;

[0045] (4) The formaldehyde-free adhesive provided by the method of the present invention has the advantage of low cost while improving the machinability of the board, and has broad application prospects. DETAILED DESCRIPTION

[0046] The following is a clear and complete description of the technical solution of the present invention in combination with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. Any equivalent transformation or substitution made by those skilled in the art based on the following implementation methods belongs to the protection scope of the present invention.

[0047] The present invention provides a method for preparing formaldehyde-free adhesive for artificial boards, comprising the following steps:

[0048] (1) Mixing a main monomer, a first initiator, an emulsifier and a solvent, and reacting them at 20-40° C. for 0.5-1 h; the main monomer is selected from two or more of ethylene, vinyl chloride, vinyl acetate and vinylidene chloride;

[0049] (2) adding a functional monomer and a second initiator to the reaction system in step (1), and continuing the reaction at 40-75° C. for 2-6 hours; the functional monomer includes but is not limited to: one or more of a compound containing a double bond and a hydroxyl group, a compound containing a double bond and a carboxyl group, a compound containing a double bond and an epoxy group, a compound containing a double bond siloxane, vinyl isobutyl ether, isobutoxymethyl acrylamide, and diacetone acrylamide;

[0050] (3) The reaction system in step (2) is reacted at 40-60° C. for 0.5-1 h, a terminator is added to obtain a polymer emulsion, and the polymer emulsion is used to prepare a formaldehyde-free adhesive.

[0051] In some examples, the polymer emulsion and the curing cross-linking agent are uniformly mixed to obtain a formaldehyde-free adhesive.

[0052] In some examples, the first initiator and the second initiator are azo initiators and / or peroxide initiators.

[0053] In some examples, the first initiator and the second initiator are used in an amount of 0.1% to 0.6% of the total monomer amount.

[0054] In some examples, the emulsifier is an anionic emulsifier and / or a nonionic emulsifier.

[0055] In some examples, the amount of the emulsifier used is 1%-8% of the total monomer amount.

[0056] In some examples, the amount of the terminator is 0.01%-0.03% of the total monomer amount.

[0057] In the following examples, unless otherwise specified, the terminator used is sorbic acid; the curing crosslinking agent used is diphenylmethane diisocyanate; the viscosity of the polymer emulsion is measured using a BROOKFIELD viscometer at room temperature, the glass transition temperature is measured by DSC, and the solid content is measured according to GB / T 27573-2011.

[0058] Example 1

[0059] This embodiment provides a method for preparing formaldehyde-free glue, and the steps are as follows:

[0060] (1) Add 250g ethylene and 700g vinyl acetate into 2000g water, add 3g potassium persulfate, 10g sodium stearate and 30g OP-10 emulsifier during stirring, and react at 30℃ for 0.5h;

[0061] (2) Add 50 g of vinyl isobutyl ether and 3 g of azobisisobutylamidine hydrochloride to the reaction system in step (1), and continue the reaction at 65° C. for 6 h;

[0062] (3) The reaction system in step (2) was reacted at 45°C for 1 hour, and 0.2 g of sorbic acid was added to obtain a polymer emulsion having a solid content of 52%, a viscosity of 2000 mPa·s, a Tg of 5°C, and a residual monomer content of 20;

[0063] (4) Mix the polymer emulsion and the curing cross-linking agent evenly to obtain formaldehyde-free glue.

[0064] Example 2

[0065] This embodiment provides a method for preparing formaldehyde-free glue, and the steps are as follows:

[0066] (1) Add 200g ethylene, 600g vinyl acetate and 120g vinyl chloride into 2000g water, add 3g potassium persulfate, 10g sodium stearate and 30g OP-10 emulsifier during stirring, and react at 35℃ for 1h;

[0067] (2) adding 80 g of 4-hydroxybutyl acrylate and 3 g of azobisisobutylamidine hydrochloride to the reaction system in step (1), and continuing the reaction at 60° C. for 5 h;

[0068] (3) The reaction system in step (2) was reacted at 50° C. for 0.5 h, and 0.2 g of sorbic acid was added to obtain a polymer emulsion having a solid content of 53%, a viscosity of 600 mPa·s, Tg=12° C., and a residual monomer content of 10;

[0069] (4) Mix the polymer emulsion and the curing cross-linking agent evenly to obtain formaldehyde-free glue.

[0070] Example 3

[0071] This embodiment provides a method for preparing formaldehyde-free glue, and the steps are as follows:

[0072] (1) Add 200g ethylene and 700g vinyl acetate into 2000g water, add 3g potassium persulfate, 10g sodium stearate and 30g OP-10 emulsifier during stirring, and react at 40℃ for 0.5h;

[0073] (2) adding 100 g of N-hydroxymethyl acrylamide and 3 g of azobisisobutylamidine hydrochloride to the reaction system in step (1), and continuing the reaction at 70° C. for 3 h;

[0074] (3) The reaction system in step (2) was reacted at 40°C for 1 hour, and 0.2 g of sorbic acid was added to obtain a polymer emulsion having a solid content of 54%, a viscosity of 3500 mPa·s, Tg=5°C, and a residual monomer content of 10;

[0075] (4) Mix the polymer emulsion and the curing cross-linking agent evenly to obtain formaldehyde-free glue.

[0076] Comparative Example 1

[0077] The preparation method of the formaldehyde-free glue in this comparative example comprises the following steps:

[0078] (1) 280 g of ethylene, 700 g of vinyl acetate, and 20 g of vinyl isobutyl ether were added to 2000 g of water, and 3 g of potassium persulfate, 3 g of azobisisobutylamidine hydrochloride, 10 g of sodium stearate, and 30 g of OP-10 emulsifier were added during stirring. The mixture was reacted at 65°C for 7.5 h, and 0.2 g of sorbic acid was added to obtain a polymer emulsion having a solid content of 52%, a viscosity of 2300 mPa·s, Tg=8°C, and a residual monomer content of 1500.

[0079] (2) Mix the polymer emulsion and the curing cross-linking agent evenly to obtain formaldehyde-free glue.

[0080] Comparative Example 2

[0081] The preparation method of the formaldehyde-free glue in this comparative example comprises the following steps:

[0082] (1) Add 280g ethylene, 700g vinyl acetate, and 20g vinyl isobutyl ether to 2000g water, add 3g potassium persulfate, 3g azobisisobutylamidine hydrochloride, 10g sodium stearate, and 30g OP-10 emulsifier during stirring, and react at 65°C for 6.5h;

[0083] (2) The above reaction system was continued to react at 40°C for 1 hour, and 0.2 g of sorbic acid was added to obtain a polymer emulsion with a solid content of 52%, a viscosity of 2800 mPa·s, Tg = 9°C, and a residual monomer content of 1200;

[0084] (3) Evenly mix the polymer emulsion and the curing cross-linking agent to obtain formaldehyde-free adhesive.

[0085] Comparative Example 3

[0086] The preparation method of the formaldehyde-free glue in this comparative example comprises the following steps:

[0087] (1) Add 280g ethylene and 700g vinyl acetate into 2000g water, add 3g potassium persulfate, 10g sodium stearate and 30g OP-10 emulsifier during stirring, and react at 65℃ for 0.5h;

[0088] (2) adding 20 g of vinyl isobutyl ether and 3 g of azobisisobutylamidine hydrochloride to the reaction system in step (1), and continuing the reaction at 65° C. for 6 h;

[0089] (3) The reaction system in step (2) was reacted at 65°C for 1 h, and 0.2 g of sorbic acid was added to obtain a polymer emulsion having a solid content of 52%, a viscosity of 2000 mPa·s, a Tg of 8°C, and a residual monomer content of 300;

[0090] (4) Evenly mix the polymer emulsion and the curing cross-linking agent to obtain formaldehyde-free adhesive.

[0091] The polymer emulsions of Examples 1-3 and Comparative Examples 1-3 and the formaldehyde-free adhesive were made into films (25 mm*25 mm*1 mm) at 110° C., and the tensile strength and elongation at break of the films were tested. The test results are shown in Table 1.

[0092] Table 1: Film properties of polymer emulsions and formaldehyde-free adhesives of Examples 1-3 and Comparative Examples 1-3

[0093]

[0094] Application Example 1

[0095] This application example is the application of the formaldehyde-free glue prepared in Example 1 in P2 particleboard, and the steps are as follows:

[0096] S1 38g of polymer emulsion and 5g of curing crosslinking agent mixed, and 1080g of surface fine sawdust grams fully stirred and set aside;

[0097] S2 84g of polymer emulsion and 10g of curing cross-linking agent were mixed, and 1616g of core coarse sawdust grams fully stirred and set aside;

[0098] S3. Use the vertical automatic hydraulic molding machine produced by Jiangsu Wuxi Yangming Rubber Machinery Co., Ltd. to press the mixed wood chips into boards with a width of 520*520*18mm according to proportion, and maintain for 72 hours.

[0099] Application Example 2

[0100] This application example is the application of the formaldehyde-free glue prepared in Example 2 in P6 particleboard, and the steps are as follows:

[0101] S1 76g of polymer emulsion and 7g of curing cross-linking agent mixed, and 1080g of surface fine sawdust grams fully stirred and set aside;

[0102] S2 129g of the polymer emulsion and 10g of curing cross-linking agent were mixed, and 1616g of coarse sawdust core grams were fully stirred and set aside;

[0103] S3. Use the vertical automatic hydraulic molding machine produced by Jiangsu Wuxi Yangming Rubber Machinery Co., Ltd. to press the mixed wood chips into boards with a width of 520*520*18mm according to proportion, and maintain for 72 hours.

[0104] Application Example 3

[0105] This application example is the application of the formaldehyde-free glue prepared in Example 3 in P10 particle board, and the steps are as follows:

[0106] S1 216g of polymer emulsion and 21g of curing crosslinking agent mixed, and 1080g of surface fine sawdust grams fully stirred and set aside;

[0107] S2 281g of polymer emulsion and 14g of curing cross-linking agent were mixed, and 1616g of core coarse sawdust grams were fully stirred and set aside;

[0108] S3. Use the vertical automatic hydraulic molding machine produced by Jiangsu Wuxi Yangming Rubber Machinery Co., Ltd. to press the mixed wood chips into boards with a width of 520*520*18mm according to proportion, and maintain for 72 hours.

[0109] Application Example 4

[0110] This application example is the application of the formaldehyde-free glue prepared in Example 1 in plywood, and the steps are as follows:

[0111] Stir 40 g of the polymer emulsion and 4 g of the curing cross-linking agent thoroughly and evenly for later use.

[0112] On two pieces of wood (25×80mm), draw a line (15×25mm) at one end, and then apply glue (glue amount 150g / m 2 ), after gluing, the two pieces of wood are pressed together with woodworking clamps and placed in a standard curing room with a temperature of 20°C and a relative humidity of 60% for 7 days.

[0113] Application Example 5

[0114] This application example is the application of the formaldehyde-free glue prepared in Example 2 in plywood, and its steps are basically the same as those in Application Example 4.

[0115] Application Example 6

[0116] This application example is the application of the formaldehyde-free glue prepared in Example 3 in plywood, and its steps are basically the same as those of Application Example 4.

[0117] Comparative application example 1

[0118] The application steps of the formaldehyde-free glue in this comparative application example in P2 particle board are basically the same as those in Application Example 1, except that the polymer emulsion used in this comparative application example is the polymer emulsion prepared in Comparative Example 1.

[0119] Three boards were pressed with the same formula as in Application Examples 1-3 and Comparative Application Example 1, and various properties were measured according to GB / T 4897-2015 "Particleboard". Each board was divided into three samples for 9 tests, and the best and worst values ​​were removed, and the average of the remaining 7 values ​​was taken. The results are shown in Table 2. The plywood of Application Examples 4-6 was tested for various properties according to the D4 standard in "EN204-Classification of Thermoplastic Wood Adhesives for Non-Structural Use", and the results are shown in Table 3.

[0120] Table 2: Particleboard performance results of application examples 1-3 and comparative application example 1

[0121]

[0122] Table 3: Performance results of plywood in application examples 4-6

[0123]

[0124] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing formaldehyde-free adhesive for artificial panels, characterized in that: The following steps are involved: (1) mixing a main monomer, a first initiator, an emulsifier and a solvent, and reacting them at 20-40° C. for 0.5-1 h; the main monomer is selected from two or more of ethylene, vinyl chloride, vinyl acetate and vinylidene chloride; (2) adding a functional monomer and a second initiator to the reaction system in step (1), and continuing the reaction at 40-75° C. for 2-6 hours; the functional monomer includes but is not limited to: one or more of a compound containing a double bond and a hydroxyl group, a compound containing a double bond and a carboxyl group, a compound containing a double bond and an epoxy group, a compound containing a double bond siloxane, vinyl isobutyl ether, isobutoxymethyl acrylamide, and diacetone acrylamide; (3) reacting the reaction system in step (2) at 40-60° C. for 0.5-1 h, adding a terminator to obtain a polymer emulsion, and using the polymer emulsion to prepare a formaldehyde-free adhesive; The compound containing double bonds and hydroxyl groups has the following structure: Wherein, R is an alkyl group containing anhydride group, carboxyl group, amino group, imino group, amide group, alkoxysilyl group, silanol group, silyl ether group, hydroxyl group, epoxy group, halogen group, mercapto group, episulfide group, or unsaturated bond functional group; The compound containing a double bond and a carboxyl group has the following structure: Wherein, R is an alkyl group containing anhydride group, carboxyl group, amino group, imino group, alkoxysilyl group, silanol group, silyl ether group, hydroxyl group, epoxy group, halogen group, mercapto group, episulfide group, or unsaturated bond functional group; The compound containing double bonds and epoxy groups has the following structure: Wherein, R is an alkyl group containing anhydride group, carboxyl group, amino group, imino group, alkoxysilyl group, silanol group, silyl ether group, hydroxyl group, epoxy group, halogen group, mercapto group, episulfide group, or unsaturated bond functional group; The double bond siloxane-containing compound has the following structure: Among them, R1, R2, and R3 are respectively an alkyl group containing anhydride group, carboxyl group, amino group, imino group, alkoxysilyl group, silanol group, silyl ether group, hydroxyl group, epoxy group, halogen group, mercapto group, episulfide group, and unsaturated bond functional group.

2. The method for preparing formaldehyde-free adhesive for artificial boards according to claim 1, characterized in that: The polymer emulsion and the curing cross-linking agent are evenly mixed to obtain the formaldehyde-free adhesive.

3. The method for preparing formaldehyde-free adhesive for artificial boards according to claim 2, characterized in that: The curing cross-linking agent is composed of one or more of the following: isocyanate containing isocyanate, adipic acid dihydrazide, melamine, trimethylol melamine, hexamethoxymethyl melamine, polyol compounds, organic amine compounds, organosilicon compounds containing double bonds, hydroxypropyl methylcellulose, and peroxide compounds.

4. The method for preparing formaldehyde-free adhesive for artificial boards according to claim 1, characterized in that: The mass ratio of the main monomer to the functional monomer is 1:(0.05-0.5).

5. The method for preparing formaldehyde-free adhesive for artificial boards according to claim 1, characterized in that: The first initiator and the second initiator are both azo initiators and / or peroxide initiators.

6. The method for preparing formaldehyde-free adhesive for artificial boards according to claim 1, characterized in that: The usage of the first initiator and the second initiator is 0.1%-0.6% of the total monomer amount.

7. The method for preparing formaldehyde-free adhesive for artificial boards according to claim 1, characterized in that: The emulsifier is an anionic emulsifier and / or a nonionic emulsifier.

8. The method for preparing formaldehyde-free adhesive for artificial boards according to claim 1, characterized in that: The amount of the emulsifier used is 1%-8% of the total monomer amount.

9. Use of the formaldehyde-free adhesive prepared by the method according to any one of claims 1 to 8 in artificial boards.

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