CN111635722B - Low-temperature curing ultralow-aldehyde water-resistant composite adhesive and preparation method thereof - Google Patents
Low-temperature curing ultralow-aldehyde water-resistant composite adhesive and preparation method thereof Download PDFInfo
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- CN111635722B CN111635722B CN202010552489.9A CN202010552489A CN111635722B CN 111635722 B CN111635722 B CN 111635722B CN 202010552489 A CN202010552489 A CN 202010552489A CN 111635722 B CN111635722 B CN 111635722B
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J161/00—Adhesives based on condensation polymers of aldehydes or ketones; Adhesives based on derivatives of such polymers
- C09J161/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C09J161/22—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds
- C09J161/24—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds with urea or thiourea
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27D—WORKING VENEER OR PLYWOOD
- B27D1/00—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring
- B27D1/04—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring to produce plywood or articles made therefrom; Plywood sheets
- B27D1/08—Manufacture of shaped articles; Presses specially designed therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27D—WORKING VENEER OR PLYWOOD
- B27D1/00—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring
- B27D1/10—Butting blanks of veneer; Joining same along edges; Preparatory processing of edges, e.g. cutting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
- B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
- B27N3/002—Manufacture of substantially flat articles, e.g. boards, from particles or fibres characterised by the type of binder
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
- C09J11/02—Non-macromolecular additives
- C09J11/06—Non-macromolecular additives organic
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
Abstract
The invention discloses a preparation method of a low-temperature curing ultralow-aldehyde waterproof composite adhesive, which is prepared from the following raw materials in parts by weight: 800 parts of isocyanate, 200 parts of linear phenolic resin, 1000 parts of urea-formaldehyde resin, 10-15 parts of a catalyst promoter and 3-6 parts of a defoaming agent. According to the invention, a new resin structure is obtained through an accurate formula design, and the resin structure simultaneously contains the characteristic structures of urea-formaldehyde resin, isocyanate and linear phenolic resin, and can have the performance advantages of three resins. The low-temperature curing ultralow-formaldehyde waterproof composite adhesive prepared by the invention has the characteristics of high curing speed, low curing temperature, simple process for bonding plates, high strength, good water resistance and ultralow formaldehyde release amount.
Description
Technical Field
The invention relates to the technical field of wood adhesives, in particular to a low-temperature curing ultralow-aldehyde water-resistant composite adhesive and a preparation method thereof.
Background
The yield of the artificial board in 2018 is 2.99 billion cubic meters, and the artificial board is usually bonded into a board by an additional adhesive and a certain processing technology when produced. The adhesive directly determines the performance of the board and is the core of the manufacture of the artificial board.
The common adhesives for the artificial board include urea-formaldehyde resin adhesives, phenol-formaldehyde resin adhesives, isocyanate adhesives and the like. Wherein the consumption of the urea-formaldehyde resin and the modified urea-formaldehyde resin (calculated by the solid content of 100%) is 1492 ten thousand tons, and accounts for more than 80% of the total consumption of the wood adhesive. It is mainly used for glued plywood, shaving board and fibre board. The urea-formaldehyde resin has the advantages of low cost, high curing speed, high dry bonding strength and the like, but the cured glue layer has poor boiling water resistance, high brittleness and easy aging, and the glued artificial board has the problem of formaldehyde release and is one of the main sources of formaldehyde pollution of indoor decorative materials.
The thermosetting phenolic resin adhesive has the advantages of high bonding strength, good chemical stability, water resistance, heat resistance, wear resistance and the like, but after the adhesive liquid is cured, a network structure is formed due to intermolecular crosslinking, so that the brittleness is high. In the curing process, thermal stress and shrinkage stress are easily generated when the temperature changes, so that the glue layer is cracked, and when the plate is subjected to external force, stress concentration is easily caused, so that the plate is broken.
The isocyanate adhesive has good water resistance and high bonding strength, is mainly used for bonding fiber boards and particle boards, but contains a large amount of micromolecule isocyanate which excessively permeates veneers to cause surface glue shortage when the veneers are bonded, so the isocyanate is not generally used for bonding the artificial boards of the veneers.
In order to solve the problems of the adhesives, researchers use the phenol modified urea-formaldehyde resin to reduce formaldehyde emission and improve water resistance and heat resistance, but the obtained modified urea-formaldehyde resin has the defects of shortened storage period, increased curing temperature and reduced curing speed, and the hot pressing efficiency is influenced. Research reports that isocyanate and urea-formaldehyde resin are mixed for use to improve the water resistance and the bonding strength of the urea-formaldehyde resin and reduce the formaldehyde emission, but actually, the two adhesives have the problems of poor component compatibility and use process. The urea-formaldehyde resin contains 45-55% of water, and isocyanate and water are easy to react during blending, so that the adhesive is cured in advance and cannot be coated. The urea-formaldehyde resin is a polar water-based resin, and the isocyanate does not contain moisture and hydrophilic groups, so that the two resins are incompatible when mixed together, and the artificial board has uneven performance. Although the problems of short opening time and compatibility can be solved to a certain extent by using blocked isocyanate or water-based isocyanate, the prepared adhesive has low reactivity, high cost and complex process, so that the energy consumption and the hot pressing efficiency are high, and the common adhesive is not applied at present.
Disclosure of Invention
Aiming at the prior art, the invention aims to provide a low-temperature curing ultralow-aldehyde waterproof composite adhesive and a preparation method thereof. According to the invention, the linear phenolic resin, the isocyanate and the urea-formaldehyde resin are mixed and blended according to a certain proportion and sequence, so that the composite adhesive which has the advantages of proper pot life, low curing temperature and high curing speed, has the structural characteristics and the performance advantages of the urea-formaldehyde resin, the linear phenolic resin and the isocyanate is prepared, and the problems of poor compatibility, high hot-pressing temperature, short pot life and low curing speed of the conventional mixed resin adhesive are solved.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a low-temperature curing ultralow-aldehyde waterproof composite adhesive, which is prepared from the following raw materials in parts by weight:
800 parts of isocyanate, 200 parts of linear phenolic resin, 1000 parts of urea-formaldehyde resin, 10-15 parts of a catalyst promoter and 3-6 parts of a defoaming agent.
Preferably, the linear phenolic resin is liquid phenolic resin, the solid content is between 85% and 90%, and the linear phenolic resin is prepared by the following method:
adding a catalyst into the phenol solution, stirring and heating to 90-95 ℃, and adjusting the pH value to 4.0-4.5 to obtain a first solution;
adding a formaldehyde solution into the first solution to enable the ratio of the aldehyde group to the phenolic hydroxyl substance to be 0.9-0.95, and preserving the heat for 90-120min to obtain a second solution;
and distilling the second solution at normal pressure to remove water, then distilling at reduced pressure to remove water, and cooling to obtain the liquid linear phenolic resin.
More preferably, the phenolic solution is phenol, a phenol derivative and/or a phenol derivative; the phenol derivative is one or a combination of resorcinol, cresol and xylenol; the phenolic derivative is one or a combination of more of a natural substance containing phenols, a biomass thermal cracking substance and a biomass liquefaction substance; wherein the natural substance containing phenols is one or two of lignin and tannin.
More preferably, the catalyst is a divalent metal oxide, a divalent metal salt or/and a divalent metal hydroxide; the divalent metal is one or more of beryllium, magnesium, calcium, strontium, barium, chromium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, mercury, lead, platinum, tin and palladium.
More preferably, the formaldehyde solution is added in two times, the amount of the first formaldehyde solution added accounts for 50-60% of the total amount of the formaldehyde solution, and the temperature is kept for 45-60min after each formaldehyde solution is added.
More preferably, the temperature for removing water by atmospheric distillation is 100-110 ℃; the temperature for removing water by reduced pressure distillation is 50-60 ℃, and the vacuum degree is 10-25 mmHg; the time for removing water by atmospheric distillation and reduced pressure distillation is 1-2 h.
The linear phenolic resin prepared by the method is light yellow in color, the average polymerization degree is 5-6, the viscosity is more than or equal to 4000 MPa.s, and the solid content is between 85 and 90 percent. The difference from the commercial phenol-formaldehyde linear resin is that the commercial phenol-formaldehyde linear resin almost contains no moisture and is solid at normal temperature, while the phenol-formaldehyde linear resin prepared by the invention contains 10-15% of moisture and is viscous liquid at normal temperature, and the subsequent composite adhesive preparation reaction can be carried out only in the liquid state, so the liquid phenol-formaldehyde linear resin is an essential raw material for synthesizing the composite adhesive in the invention.
Preferably, the isocyanate is one or more of toluene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, isophorone diisocyanate or polymethylene polyphenyl isocyanate.
Preferably, the urea-formaldehyde resin is a urea-formaldehyde resin which is commercially available or prepared by self, wherein the amount ratio of formaldehyde to urea is 0.95-1.25, the solid content is 50% -60%, and the viscosity is 500-1500 MPa.s.
Preferably, the catalyst promoter is N, N-dimethylcyclohexylamine, bis (2-dimethylaminoethyl) ether, triethylenediamine, N, N, N ', N' -tetramethylalkylenediamine, N, N, N ', N', N '-pentamethyldiethylenetriamine, triethylamine, N, N-dimethylbenzylamine, N, N-dimethylhexadecylamine, N, N-dimethylbutylamine, triethylenediamine, N-ethylmorpholine, N-methylmorpholine, N, N' -diethylpiperazine, N, N '-diethyl-2-methylpiperazine, N, N' -bis- (alpha-hydroxypropyl) -2-methylpiperazine, N-2-hydroxypropyldimethylmorpholine, triethanolamine, N, N-dimethylethanolamine, N, N-dimethylaminoethanol-amine, N, N-dimethylethanolamine, N-dimethylhexylamine, N, pyridine, N' -dimethylpyridine, stannous octoate, dibutyltin dilaurate, bismuth isooctanoate, bismuth laurate, bismuth neodecanoate and bismuth naphthenate.
The catalyst accelerator of the present invention selectively catalyzes the reaction between the isocyanate group of the isocyanate and the phenolic hydroxyl group of the phenol novolac resin in the reaction liquid, and suppresses the reaction between the isocyanate group and the moisture in the phenol novolac resin.
Preferably, the defoaming agent is one or more of organic polyether ester, dimethyl silicone oil, diethyl silicone oil and silicone oil emulsion.
The second aspect of the invention provides a preparation method of the low-temperature curing ultralow-aldehyde water-resistant composite adhesive, which comprises the following steps:
(1) adding a catalytic promoter and a defoaming agent into isocyanate, heating to 45-55 ℃, then gradually adding the linear phenolic resin within 0.5-1h, and continuously stirring for 0.5-1h to obtain mixed resin;
(2) adding urea-formaldehyde resin into the mixed resin obtained in the step (1), stirring for 0.5-1h, and cooling to room temperature to obtain the low-temperature cured ultralow-aldehyde water-resistant composite adhesive.
The third aspect of the invention provides an application of the low-temperature cured ultralow-aldehyde waterproof composite adhesive in producing artificial boards.
In the application, the artificial board comprises plywood, laminated veneer lumber, a multi-layer solid wood composite floor, a laminated wood board, finger joint material, laminated wood and the like.
The fourth aspect of the invention provides a method for producing artificial boards, comprising the following steps:
coating the low-temperature cured ultralow-aldehyde water-resistant composite adhesive on a wood single plate, assembling, and performing compression molding after the assembly is finished to obtain an artificial board;
the pressure of the compression molding is 0.5-4.5MPa, the temperature is more than or equal to 80 ℃, and the heat seal time is 3-4 min.
Preferably, the assembly mode is one or more of the vertical texture of the adjacent single plates, the parallel texture of the adjacent single plates or the arrangement of the adjacent single plates at any other angle.
Preferably, the wood veneer is a needle-leaf or broad-leaf veneer with various thicknesses and water contents, which is processed by rotary cutting, slicing, sawing and the like.
Preferably, the coating mode is one of curtain coating, spraying, roller coating and brush coating.
Preferably, the coating amount of the low-temperature curing ultralow-aldehyde water-resistant composite adhesive is 220-250g/m on both sides2。
The invention has the beneficial effects that:
the low-temperature curing ultralow-aldehyde water-resistant composite adhesive prepared by the invention has the following characteristics:
(1) the low-temperature curing ultralow-aldehyde water-resistant composite adhesive prepared by the invention has the advantages of urea-formaldehyde resin, linear phenolic resin and isocyanate, and the defects of the urea-formaldehyde resin, the linear phenolic resin and the isocyanate are eliminated. Through the accurate component proportion design, the composite adhesive has the structural characteristics of the three adhesives (shown in figure 1), has proper molecular weight and viscosity, high curing speed and low curing temperature, is suitable for the glue joint of single-plate artificial boards, and has the advantages of simple process operation, boiling water resistance and ultralow formaldehyde release amount.
(2) In the composite adhesive, the urea-formaldehyde resin mainly provides the cohesion and hardness of the adhesive and reduces the cost, and a small amount of free formaldehyde can assist in curing the linear phenolic resin; the linear phenolic resin is used for expanding molecular chains of isocyanate, combining phenolic hydroxyl with the isocyanate, changing the molecular chain structure, increasing the toughness, simultaneously improving the compatibility of the urea-formaldehyde resin and the isocyanate, prolonging the service life, reacting with free formaldehyde of the urea-formaldehyde resin and reducing the formaldehyde content; the isocyanate is mainly used for simultaneously connecting the linear phenolic resin and the urea-formaldehyde resin and increasing the network structure density of the adhesive, and the residual isocyanate in the composite adhesive can be combined with wood to generate a chemical bond so as to improve the adhesive force between the composite adhesive and the wood.
(3) The composite adhesive prepared by the invention can effectively reduce energy consumption and improve hot-pressing efficiency; the hot-pressing temperature of the common urea-formaldehyde resin is more than or equal to 120 ℃, the hot-pressing time is more than or equal to 4min, the hot-pressing temperature of the isocyanate is more than or equal to 140 ℃, the hot-pressing time is more than or equal to 6min, the hot-pressing temperature required by the composite adhesive is low (more than or equal to 80 ℃), the hot-pressing time is short (3-4min), and the energy consumption is effectively reduced.
(4) The plywood glued by the common urea-formaldehyde resin generally reaches the national standard GB17657-2013 physical and chemical properties of artificial boards and decorative artificial boardsTest method for the requirement of type II plywood (water resistance), the formaldehyde emission is more than or equal to 0.12mg/m3. The plywood glued by the composite adhesive prepared by the invention can meet the requirements of I-type plywood (boiling water resistance), and the formaldehyde emission is less than or equal to 0.04mg/m3。
(5) The composite adhesive prepared by the invention can be used for manufacturing medium-high grade plywood, laminated wood boards, multi-layer solid wood composite floors, laminated veneer lumber and other wood composite boards, and is applied to the fields of carriage manufacturing, indoor building materials, high-grade furniture, waterproof floors and the like. Besides, the adhesive is also suitable for bonding various biomass fiber materials such as bamboo, straw, cotton stalk, hemp stalk and the like.
Drawings
FIG. 1: the structure schematic diagram of the low-temperature curing ultralow-aldehyde water-resistant composite adhesive curing bonded wood is shown.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
Description of terms:
the term "room temperature" as used herein means a temperature of 15 to 25 ℃.
As described in the background art, because the existing urea-formaldehyde resin adhesives and isocyanate adhesives have certain defects, the phenolic resins are divided into two types, one is a thermosetting phenolic resin, i.e., a common ordinary phenolic resin, and the other is a thermoplastic phenolic resin, i.e., a linear phenolic resin. The two phenolic resins are similar in reaction raw materials (both are formaldehyde and phenol), but different in catalysts for reaction (basic catalyst for common phenolic resin and acidic catalyst for linear phenolic resin) and different in proportion of the reaction raw materials, wherein the molar ratio of the formaldehyde to the phenol in the common phenolic resin is generally between 1.8 and 2.2, and the molar ratio of the formaldehyde to the phenol in the linear phenolic resin is generally between 0.75 and 0.95. Ordinary phenolic resin can be directly solidified into solid resin at high temperature, and linear phenolic resin has the hot melting property, can be only melted at high temperature, can be changed into solid state when being cooled, and can be converted into thermosetting resin for final solidification only by adding other substances, so that the linear phenolic resin is less applied to the wood processing industry. When the urea-formaldehyde resin and the isocyanate are blended for use, the isocyanate groups can react with water and hydroxyl groups immediately after contacting with the water, so that the opening time of the adhesive is too short, the assembly of the adhesive cannot be normally glued, and the compatibility of the two adhesives is poor. Although the problem of short open time can be solved to a certain extent by using blocked isocyanate or water-based isocyanate, the prepared composite adhesive has low reactivity and can be cured only by hot pressing at a high temperature, so that the energy consumption is high and the hot pressing efficiency is low. Based on the above, the invention aims to provide a novel low-temperature curing ultralow-aldehyde water-resistant composite adhesive and a preparation method thereof, so as to solve the problems of the existing adhesive.
The low-temperature curing ultralow-aldehyde water-resistant composite adhesive disclosed by the invention obtains a new resin structure through accurate formula design, simultaneously contains the characteristic structures (shown in figure 1) of urea-formaldehyde resin, isocyanate and linear phenolic resin, and can have the performance advantages of the three resins. The urea-formaldehyde resin mainly provides a main body structure of the composite adhesive and endows the adhesive with cohesive strength and hardness. Free formaldehyde existing in the urea-formaldehyde resin can play a role in assisting in curing the linear phenolic resin, so that the formaldehyde content is greatly reduced; the degree of polymerization of the synthesized linear phenolic resin is 5-6, so that the flexibility of the adhesive can be increased, the brittleness can be improved, the linear phenolic resin can react with a small molecular isocyanate monomer, the molecular weight of isocyanate is increased, and the permeation into a single plate is reduced. The linear phenolic resin can react with isocyanate on one hand, and has similar polarity with urea-formaldehyde resin on the other hand, so that the compatibility between the urea-formaldehyde resin and the isocyanate can be improved; the isocyanate can respectively cross-link the linear phenolic resin and the urea-formaldehyde resin, so that the structural density of the cured adhesive is improved, and meanwhile, through the formula design, a certain amount of isocyanate groups in the composite adhesive are abundant, so that the composite adhesive is reacted with hydroxyl and water in wood, and is used for adhering and curing the wood, so that the bonding force between the wood and the wood is improved. The low-temperature curing ultralow-aldehyde waterproof composite adhesive designed by the accurate components has the advantages of three resins, high curing speed, low curing temperature, simple process of cementing artificial boards, boiling water resistance, high strength and ultralow formaldehyde release amount.
In the preparation process of the multi-component high-strength waterproof composite adhesive, the adding sequence of the raw materials is very critical, and the linear phenolic resin plays a role of a compatible agent or a coupling agent in the adhesive, so that the linear phenolic resin reacts with isocyanate on one hand and urea-formaldehyde resin on the other hand. The linear phenolic resin and the urea-formaldehyde resin belong to polar resins, and the linear phenolic resin and the urea-formaldehyde resin have good compatibility, while the isocyanate belongs to nonpolar resins and is not compatible with the polar resins. The linear phenolic resin is firstly chemically reacted with isocyanate, so that partial isocyanate is connected with phenolic resin molecular chains and has certain polarity, and therefore, the compatibility is improved when the linear phenolic resin is mixed with urea-formaldehyde resin. Therefore, the adding sequence of the raw materials is very critical, and the composite adhesive with the effect of the invention cannot be obtained by changing the sequence.
In order to make the technical solutions of the present application more clearly understood by those skilled in the art, the technical solutions of the present application will be described in detail below with reference to specific embodiments.
The test materials used in the examples of the present invention are all conventional in the art and commercially available. Wherein: the isocyanate is diphenylmethane diisocyanate available from BASF corporation under the trade name Lupranate M20; urea-formaldehyde resin is commercially available, the solid content is 50%, the mass ratio of formaldehyde to urea is 1.05, and the viscosity is 600 MPa.s.
The preparation method of the linear phenolic resin in the embodiment of the invention comprises the following steps:
(1) 200 parts of a 37 mass% formaldehyde solution and 260 parts of a 99 mass% phenol solution were taken.
Adding a phenol solution into a reaction kettle at one time, adding 3 parts of zinc oxide, stirring and heating to 95 ℃, and adjusting the pH value to 4.0 by using a 20% nitric acid solution to obtain a first solution;
(2) adding 120 parts of formaldehyde solution into the first solution obtained in the step (1), preserving heat for 45min, then adding 80 parts of formaldehyde solution, and preserving heat for 60min to obtain a second solution;
(3) and distilling the second solution at the temperature of 110 ℃ under normal pressure for removing water for 1.5h, then carrying out reduced pressure distillation for removing water for 1h under the conditions of the temperature of 60 ℃ and the vacuum degree of 10-25mmHg, relieving the vacuum, and cooling the temperature to room temperature to obtain light yellow liquid linear phenolic resin, wherein the average polymerization degree is 5-6, the viscosity is not less than 4000MPa s, and the solid content is 85-90%.
Example 1:
adding 10 parts of triethylamine and 3 parts of methylene silicon oil into 600 parts of isocyanate, heating to 50 ℃, gradually adding 200 parts of linear phenolic resin within 0.5h, and stirring for 0.5h to obtain mixed resin of the linear phenolic resin and the isocyanate; adding 800 parts of urea-formaldehyde resin into the mixed resin of the linear phenolic resin and the isocyanate, stirring for 0.5h, and cooling to room temperature to prepare the low-temperature cured ultralow-aldehyde water-resistant composite adhesive.
The performance indexes of the low-temperature curing ultralow-aldehyde water-resistant composite adhesive prepared in the embodiment are shown in table 1.
Example 2:
adding 12 parts of triethylamine and 5 parts of methylene silicon oil into 700 parts of isocyanate, heating to 50 ℃, gradually adding 250 parts of linear phenolic resin within 0.5h, and stirring for 0.5h to obtain mixed resin of the linear phenolic resin and the isocyanate; adding 900 parts of urea-formaldehyde resin into the mixed resin of the linear phenolic resin and the isocyanate, stirring for 0.5h, and cooling to room temperature to obtain the low-temperature cured ultralow-aldehyde water-resistant composite adhesive.
The performance indexes of the low-temperature curing ultralow-aldehyde water-resistant composite adhesive prepared in the embodiment are shown in table 1.
Example 3:
adding 750 parts of isocyanate, 15 parts of triethylamine and 6 parts of methylene silicon oil, heating to 50 ℃, then gradually adding 300 parts of linear phenolic resin within 1 hour, and stirring for 0.5 hour to obtain mixed resin of the linear phenolic resin and the isocyanate; and taking 1000 parts of urea-formaldehyde resin, adding the urea-formaldehyde resin into the mixed resin of the linear phenolic resin and the isocyanate, stirring for 0.5h, and cooling to room temperature to obtain the low-temperature cured ultralow-aldehyde water-resistant composite adhesive.
The performance indexes of the low-temperature curing ultralow-aldehyde water-resistant composite adhesive prepared in the embodiment are shown in table 1.
Comparative example 1: the urea-formaldehyde resin is directly used as the adhesive.
Comparative example 2: isocyanate is directly used as an adhesive.
Comparative example 3: the linear phenolic resin is directly used as an adhesive.
Comparative example 4:
and (3) taking 600 parts of isocyanate and 800 parts of urea-formaldehyde resin, uniformly mixing, and stirring for 0.5h to obtain the adhesive A.
Comparative example 5:
adding 10 parts of triethylamine and 3 parts of silicone oil emulsion into 600 parts of isocyanate, heating to 50 ℃, then gradually adding 200 parts of linear phenolic resin within 1 hour, stirring for 0.5 hour, and cooling to room temperature to obtain the adhesive B.
Comparative example 6:
and (3) uniformly mixing 200 parts of linear phenolic resin and 800 parts of urea-formaldehyde resin, and stirring for 0.5h to obtain the adhesive C.
Verification example:
the low-temperature curing ultralow-formaldehyde waterproof composite adhesive prepared in the above examples 1-3 is respectively used for pressing three-layer plywood. The specific operation is as follows: coating the composite adhesive on a birch veneer, wherein the adhesive coating amount is as follows: 250g/m2. The birch veneer has a thickness of 1.6-1.7mm, a breadth of 300 × 300mm, and a water content of 10-12%. After gluing, closing and aging for 16min, and then hot pressing for 4.0min under the pressure of 1.1MPa, wherein the hot pressing temperature is 90 ℃.
Three-ply plywood was pressed as described above with the adhesives prepared in comparative examples 1-6 as a control.
The three-layer plywood prepared by the method is tested for boiling water resistant bonding strength according to the requirements of class I plywood in national standard GB17657 plus 2013 physicochemical property experimental method for artificial boards and decorative artificial boards (a test piece is soaked in boiling water for 4 hours, then dried in a forced air drying oven at 63 ℃ for 16-20 hours, soaked in boiling water for 4 hours, and then placed in cold water at the temperature lower than 30 ℃ for 1 hour). The performance test results of the plywood prepared using the low-temperature curing ultra-low formaldehyde water-resistant composite adhesives of examples 1 to 3 and the plywood prepared using the adhesives of comparative examples 1 to 6 are shown in table 2.
Table 1: performance index of adhesive
Reference standard: the national standard GB14074-2017 Wood adhesive and resin inspection method thereof.
Table 1 illustrates: the low-temperature curing ultralow-aldehyde water-resistant composite adhesive disclosed by the invention is proper in viscosity, short in curing time and suitable for the production requirements of plywood.
Table 2: plywood bonding strength test results
Reference standard: the national standard GB17657-2013 physicochemical property experimental method for artificial boards and veneer artificial boards and GB/T35601-2017 green product evaluation artificial boards and wood floors.
Table 2 illustrates: the plywood prepared by the low-temperature curing ultralow-formaldehyde water-resistant composite adhesive meets the requirements of national standard I-type plywood, while the plywood prepared by the adhesives in comparative examples 1-6 has obviously reduced boiling water resistant bonding strength, and part of the plywood cannot be pressed. The result shows that the raw materials of the components of the low-temperature curing ultralow-aldehyde water-resistant composite adhesive are an organic whole, and the performance of the prepared adhesive is obviously reduced by reducing or changing the composition of the raw materials.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. The low-temperature curing ultralow-aldehyde waterproof composite adhesive is characterized by being prepared from the following raw materials in parts by weight:
800 parts of isocyanate 600-containing material, 300 parts of linear phenolic resin 200-containing material, 1000 parts of urea-formaldehyde resin 800-containing material, 10-15 parts of catalytic promoter and 3-6 parts of defoaming agent;
the catalyst promoter is N, N-dimethylcyclohexylamine, bis (2-dimethylaminoethyl) ether, triethylenediamine, N, N, N ', N ' -tetramethylalkylenediamine, N, N, N ', N ' ', N ' ' -pentamethyldiethylenetriamine, triethylamine, N, N-dimethylbenzylamine, N, N-dimethylhexadecylamine, N, N-dimethylbutylamine, triethylenediamine, N-ethylmorpholine, N-methylmorpholine, N, N ' -diethylpiperazine, N, N ' -diethyl-2-methylpiperazine, N, N ' -bis- (alpha-hydroxypropyl) -2-methylpiperazine, N-2-hydroxypropyldimethylmorpholine, triethanolamine, N, N-dimethylethanolamine, N, N ' -dimethylethanolamine, N, N ' -dimethyldiethanolamine, N, N ' -dimethyldiethylenetriamine, N, N, N-dimethylhexamethylenediamine, one or more of pyridine, N' -dimethylpyridine, stannous octoate, dibutyltin dilaurate, bismuth isooctanoate, bismuth laurate, bismuth neodecanoate and bismuth naphthenate;
the linear phenolic resin is prepared by the following method:
adding a catalyst into the phenol solution, stirring and heating to 90-95 ℃, and adjusting the pH value to 4.0-4.5 to obtain a first solution;
adding formaldehyde solution into the first solution to enable the ratio of the aldehyde group to the phenolic hydroxyl substance to be 0.9-0.95, and preserving heat for 80-120min to obtain a second solution;
distilling the second solution at normal pressure to remove water, then distilling at reduced pressure to remove water, and cooling to obtain linear phenolic resin;
the catalyst is a divalent metal oxide, a divalent metal salt or/and a divalent metal hydroxide; the divalent metal is one or more of beryllium, magnesium, calcium, strontium, barium, chromium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, mercury, lead, platinum, tin and palladium;
adding formaldehyde solution twice, wherein the amount of the first added formaldehyde solution accounts for 50-60% of the total amount of the formaldehyde solution, and keeping the temperature for 45-60min after adding the formaldehyde solution every time;
the temperature for removing water by normal pressure distillation is 100-110 ℃; the temperature for removing water by reduced pressure distillation is 50-60 ℃, and the vacuum degree is 10-25 mmHg; the time for removing water by atmospheric distillation and reduced pressure distillation is 1-2 h.
2. The low-temperature-curing ultralow-aldehyde water-resistant composite adhesive according to claim 1, wherein the phenolic solution is phenol or a phenolic derivative.
3. The low-temperature-curing ultralow-aldehyde water-resistant composite adhesive as claimed in claim 1, wherein the isocyanate is one or more of toluene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, isophorone diisocyanate or polymethylene polyphenyl isocyanate.
4. The preparation method of the low-temperature curing ultralow-aldehyde water-resistant composite adhesive as claimed in any one of claims 1 to 3, comprising the following steps:
(1) adding a catalytic promoter and a defoaming agent into isocyanate, heating to 45-55 ℃, then gradually adding the linear phenolic resin within 0.5-1h, and continuously stirring for 0.5-1h to obtain mixed resin;
(2) adding urea-formaldehyde resin into the mixed resin obtained in the step (1), stirring for 0.5-1h, and cooling to room temperature to obtain the low-temperature cured ultralow-aldehyde water-resistant composite adhesive.
5. Use of the low temperature curing ultra-low aldehyde water-resistant composite adhesive of any one of claims 1 to 3 in the production of artificial boards.
6. Use according to claim 5, wherein the artificial board comprises: plywood, laminated veneer lumber, multi-layer solid wood composite flooring, core-board, finger-jointed lumber, and/or laminated lumber.
7. The production method of the artificial board is characterized by comprising the following steps:
coating the low-temperature curing ultralow-aldehyde water-resistant composite adhesive as defined in any one of claims 1 to 3 on a wood veneer, assembling, and performing compression molding after the assembly to obtain an artificial board;
the pressure of the compression molding is 0.5-4.5MPa, the temperature is more than or equal to 80 ℃, and the heat seal time is 3-4 min.
8. The method for producing the laminated veneer, according to claim 7, is characterized in that the assembling mode is one or more of vertical grain of adjacent veneers, parallel grain of adjacent veneers, or arrangement of adjacent veneers at any other angle.
9. The production method according to claim 7, wherein the coating manner is one of curtain coating, spray coating, roll coating and brush coating.
10. The production method as claimed in claim 7, wherein the coating amount of the low-temperature curing ultralow-formaldehyde water-resistant composite adhesive is 220-two-sided adhesive at 250g/m2。
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