Phenolic resin wood adhesive
By combining the aminolated phenolic resin with dialdehyde, a low-temperature fast curing phenolic resin adhesive is formed, which solves the high-temperature curing and low toughness problems of traditional phenolic resins, and realizes high-strength and high-toughness wood adhesives, which improves the production efficiency and application range of artificial boards.
Patent Information
- Application Number
- CN202510701385.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-28
- Publication Date
- 2025-08-15
AI Technical Summary
Traditional phenolic resins have problems such as high curing temperature, slow curing speed and poor impact toughness, resulting in large energy consumption, low efficiency and limited application range of artificial boards.
The combination of amino-dehyde resin and dialdehyde is adopted, and the molar ratio of amino-aldehyde groups is 1:(1-2). Cross-linking is made at low temperature to form an imine bond as a weak crosslinking point, connecting the long chain of linear phenolic resin to promote rapid curing and enhance toughness.
It realizes fast curing of phenolic resin at low temperature, improves bonding strength and impact toughness, solves the hard and brittle problems of traditional phenolic resins, reduces production energy consumption and improves production efficiency.
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Figure CN120484742A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of wood adhesives, in particular to a phenolic resin wood adhesive. Background Art
[0002] Traditional phenolic resins still face problems such as high curing temperature, slow curing speed and poor toughness, which results in high energy consumption, low efficiency and limited application range in the production of artificial boards.
[0003] The high strength and aging resistance of phenolic resin adhesives stem from their strong covalent crosslinking structure. If these covalent bonds are converted to dynamic covalent bonds, the resin's performance may deteriorate after curing. First, imine bonds are easily broken, which, while toughening the polymer, can also reduce its strength and water resistance. Second, exchange reactions of imine bonds under external stimuli can make the polymer network susceptible to creep, resulting in reduced dimensional stability. Summary of the Invention
[0004] The present invention provides a phenolic resin wood adhesive for solving the problems of high curing temperature, poor impact toughness and the like existing in traditional phenolic resins.
[0005] According to a first aspect of the present invention, a phenolic resin wood adhesive comprises an amino phenolic resin and a dialdehyde, wherein the molar ratio of primary amino groups in the amino phenolic resin to aldehyde groups in the dialdehyde is 1:(1-2).
[0006] Furthermore, the structural formula of the amino phenolic resin is as follows:
[0007]
[0008] In the above scheme, the phenolic resin wood adhesive of the present invention is compounded by amino-phenolic resin and dialdehyde. The primary amino groups and aldehyde groups in the amino-phenolic resin can cross-link at a temperature below 100°C, thereby effectively promoting the rapid curing of the phenolic resin at low temperature, solving the problems of high curing temperature and slow curing speed of traditional phenolic resin. In addition, the imine bonds formed by the cross-linking of the primary amino groups and aldehyde groups can serve as weak cross-linking points to connect the long chains of linear phenolic resin. During the stress-damage process of the resin, the imine bonds will preferentially break and dissipate energy, while redistributing stress in the phenolic resin chains and preventing crack growth, thereby achieving the strengthening and toughening of the phenolic resin.
[0009] Furthermore, the pH value is 3-6.
[0010] Alternatively, the molar ratio of the primary amino groups in the amino-phenolic resin to the aldehyde groups in the dialdehyde can be 1:1, 1:1.2, 1:1.4, or 1:2, or other values within the aforementioned range, without limitation. The pH of the compounded adhesive can be 3, 4, 5, or 6, or other values within the aforementioned range, without limitation.
[0011] In the above scheme, by limiting the molar ratio of the primary amino group in the amino-phenolic resin to the aldehyde group in the dialdehyde and the pH value of the compounded adhesive within a reasonable range, the components can achieve better synergistic effects and better improve the curing speed, toughness and strength of the phenolic resin.
[0012] Furthermore, the amino phenolic resin is prepared by a Mannich reaction between a thermoplastic phenolic resin and a polyamine.
[0013] In the above scheme, the polyamine and formaldehyde react with the active hydrogen of the benzene ring in the thermoplastic phenolic resin through the Mannich reaction to achieve the amino modification of the thermoplastic phenolic resin.
[0014] Furthermore, the polyamine is one or both of diethylenetriamine and triethylenetetramine.
[0015] Furthermore, the average molecular weight of the thermoplastic phenolic resin is 500 to 2000 Da.
[0016] By optimizing the type of polyamine and limiting the molecular weight of the thermoplastic phenolic resin within a reasonable range, the raw materials can play a better synergistic role, thereby improving the curing speed, strength and toughness of the modified phenolic resin.
[0017] Furthermore, the dialdehyde is one or more of glyoxal, terephthalaldehyde and 2,5-furandicarboxaldehyde.
[0018] In the above scheme, the modified phenolic resin has better curing speed, toughness and strength through the reasonable selection of dialdehyde.
[0019] Furthermore, the dialdehyde is stirred and mixed with an amino phenolic resin solution to obtain a modified phenolic resin.
[0020] Furthermore, the structural formula of the modified phenolic resin is as follows:
[0021]
[0022] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-mentioned phenolic resin wood adhesive, comprising the following steps:
[0023] Step (1): dissolving an amino phenolic resin in water, and then adjusting the pH value to obtain an amino phenolic resin solution;
[0024] Step (2): adding dialdehyde to the amino phenolic resin solution, stirring and mixing to obtain a modified phenolic resin wood adhesive.
[0025] In the above scheme, the preparation method of the present invention compounds amino phenolic resin and dialdehyde to prepare modified phenolic resin, and after the resin is cured, the long chains of linear phenolic resin are connected using imine bonds as cross-linking points. Based on the easy bonding characteristics of the imine bond and the weak covalent bond toughening strategy, the modified phenolic resin is made strong, tough and fast-curing.
[0026] The technical solution provided by the present invention has the following beneficial effects:
[0027] The present invention provides a phenolic resin wood adhesive that simultaneously exhibits fast curing speed, high bonding strength, and impact toughness, resolving issues such as high curing temperature, slow curing speed, and a hard and brittle cured adhesive layer associated with conventional phenolic resins. The tough, fast-curing phenolic resin wood adhesive comprises an amino-modified phenolic resin and a dialdehyde, effectively avoiding the significant shortening of the resin's pot life caused by modification methods such as curing agents and the high cost of resorcinol modification, while also overcoming the hard and brittle cured adhesive layer associated with the modified resin. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0029] Figure 1 These are the infrared, XPS and NMR spectra of the thermoplastic phenolic resin, amino phenolic resin and modified phenolic resin in Example 1 of the present invention.
[0030] Figure 2 1. The infrared and XPS spectra of terephthalaldehyde, amino phenolic resin and modified phenolic resin in Example 1 of the present invention, as well as the possible cross-linking reaction principle of the modified resin.
[0031] Figure 3 It is the structural formula of modified phenolic resin.
[0032] Figure 4 It is the structural formula of amino phenolic resin. DETAILED DESCRIPTION
[0033] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.
[0034] The beneficial effects of the present invention will be described below with reference to specific embodiments and comparative examples.
[0035] Example 1
[0036] This embodiment provides a phenolic resin wood adhesive, and its preparation method is as follows:
[0037] (1) Dissolve 25 parts of a thermoplastic phenolic resin with a molecular weight of 500 Da in an ethanol / water solution, adjust the pH value of the solution to 9, then add 33 parts of diethylenetriamine, raise the temperature to 75°C, dropwise add 39.6 parts of formaldehyde solution, keep the temperature at 75°C for 4 hours after the addition, and freeze-dry to obtain an amino-phenolic resin. The structural formula of the amino-phenolic resin is as follows: Figure 4 shown.
[0038] The infrared, XPS and NMR spectra of thermoplastic phenolic resin, amino phenolic resin and modified phenolic resin are as follows: Figure 1 As shown, the amino phenolic resin is at 3306 cm -1 There is an NH stretching vibration peak near 1655cm -1 and 1465cm -1 The characteristic peaks corresponding to NH and CN were observed at Figure 1 a), confirming that diethylenetriamine was successfully grafted into thermoplastic phenolic resin. XPS spectrum showed that the nitrogen element in the amino phenolic resin accounted for 10.54% ( Figure 1 b). The relative content of CO peak in thermoplastic phenolic resin is 10.04% ( Figure 1 c), while the relative content of CO / CN peak in amino phenolic resin increased sharply, reaching 48.54% ( Figure 1 d). The N1s spectrum of amino-phenolic resin can be deconvoluted into two peaks corresponding to CN (399.4eV) and NH (401.4eV) groups ( Figure 1 e). For the NMR spectrum of the aminophenolic resin, the chemical shifts at 2.72 and 2.57 ppm (labeled as d and e) are attributed to the protons of the methylene group (-N-CH2-CH2-NH2) in diethylenetriamine ( Figure 1 f). These changes confirmed the successful synthesis of the amino-phenolic resin.
[0039] (2) Dissolve 22 parts of amino phenolic resin in 43 parts of water, adjust the pH value to 5, then add 13 parts of terephthalaldehyde, and stir evenly at 20-25 degrees to obtain modified phenolic resin, i.e., modified phenolic resin adhesive. The structural formula of the modified phenolic resin is as follows: Figure 3 shown.
[0040] The infrared and XPS spectra of terephthalaldehyde, amino phenolic resin and modified phenolic resin are as follows: Figure 2 The FTIR spectrum of the modified phenolic resin showed that the C=N bond corresponding to 1701 cm -1 The peak at ( Figure 2 a). XPS spectrum of modified phenolic resin at 285.6eV ( Figure 2 b) and 398.6eV( Figure 2 c) produces characteristic peaks of C=O / C=N and -N=. The modified phenolic resin shows a characteristic π-π* interaction peak at 291.3 eV ( Figure 2 b), which is due to the π-π conjugated structure between the imine bond and the adjacent benzene ring. These results indicate that the amino phenolic resin reacts with terephthalaldehyde to form an imine bond, constructing a phenolic resin cross-linked structure in which the linear phenolic resin long chains are connected with weak imine bonds as cross-linking points ( Figure 2 d).
[0041] Example 2
[0042] This embodiment provides a phenolic resin wood adhesive, and its preparation method is as follows:
[0043] (1) 25 parts of a 1000 Da thermoplastic phenolic resin were dissolved in an ethanol / water solution, the pH of the solution was adjusted to 9, 37 parts of diethylenetriamine were added, the temperature was raised to 75°C, 36 parts of a 37% formaldehyde solution was added dropwise, and the mixture was kept at 75°C for 4 h. The amino-phenolic resin was obtained after freeze-drying.
[0044] (2) Dissolve 22 parts of amino phenolic resin in 43 parts of water, adjust the pH value to 5, then add 13 parts of glyoxal, and stir evenly to obtain a modified phenolic resin adhesive.
[0045] Example 3
[0046] This embodiment provides a phenolic resin wood adhesive, and its preparation method is as follows:
[0047] (1) 25 parts of a 1000 Da thermoplastic phenolic resin were dissolved in an ethanol / water solution, and the pH of the solution was adjusted to 9. Then, 41 parts of triethylenetetramine were added, and the temperature was raised to 75°C. 27.6 parts of a 37% formaldehyde solution was added dropwise. After the addition was complete, the mixture was kept at 75°C for 4 hours and freeze-dried to obtain an amino-phenolic resin.
[0048] (2) Dissolve 22 parts of amino phenolic resin in 43 parts of water, adjust the pH value to 5, then add 13 parts of terephthalaldehyde, and stir evenly to obtain a modified phenolic resin adhesive.
[0049] Example 4
[0050] This embodiment provides a phenolic resin wood adhesive, and its preparation method is as follows:
[0051] (1) 25 parts of a thermoplastic phenolic resin with a molecular weight of 1500 Da were dissolved in an ethanol / water solution, the pH value of the solution was adjusted to 9, 45 parts of triethylenetetramine was added, the temperature was raised to 75°C, 30.3 parts of formaldehyde solution (37%) was added dropwise, and the mixture was kept at 75°C for 4 hours. After freeze-drying, an amino-phenolic resin was obtained.
[0052] (2) Dissolve 22 parts of amino phenolic resin in 43 parts of water, adjust the pH value to 5, then add 13 parts of glyoxal, and stir evenly to obtain a modified phenolic resin adhesive.
[0053] Example 5
[0054] This embodiment provides a phenolic resin wood adhesive, and its preparation method is as follows:
[0055] (1) 25 parts of a 2000 Da thermoplastic phenolic resin were dissolved in an ethanol / water solution, the pH of the solution was adjusted to 9, 37 parts of diethylenetriamine were added, the temperature was raised to 75°C, 36 parts of a 37% formaldehyde solution was added dropwise, and the mixture was kept at 75°C for 4 hours. The amino-phenolic resin was obtained after freeze-drying.
[0056] (2) Dissolve 22 parts of amino phenolic resin in 43 parts of water, adjust the pH value to 4, then add 13 parts of terephthalaldehyde, and stir evenly to obtain a modified phenolic resin adhesive.
[0057] Example 6
[0058] This embodiment provides a phenolic resin wood adhesive, and its preparation method is as follows:
[0059] (1) 25 parts of a 1000 Da thermoplastic phenolic resin were dissolved in an ethanol / water solution, the pH of the solution was adjusted to 9, 37 parts of diethylenetriamine were added, the temperature was raised to 75°C, 36 parts of a 37% formaldehyde solution was added dropwise, and the mixture was kept at 75°C for 4 h. The amino-phenolic resin was obtained after freeze-drying.
[0060] (2) Dissolve 22 parts of amino phenolic resin in 43 parts of water, adjust the pH value to 3, then add 13 parts of glyoxal, and stir evenly to obtain a modified phenolic resin adhesive.
[0061] Comparative Example 1
[0062] This comparative example provides a resol phenolic resin adhesive, and its preparation method is as follows:
[0063] 50 parts of phenol, 40 parts of water, 75 parts of formaldehyde solution, and 25 parts of sodium hydroxide solution (40%) are mixed, and then reacted at 90°C for 50 minutes; after adding 22 parts of formaldehyde solution (37%) and 5 parts of sodium hydroxide solution (40%), the mixture is kept warm and reacted at 90°C for 30 to 50 minutes. When the viscosity of the reaction system is measured by a grid tube and is 1.5 to 2 seconds, the mixture is cooled to room temperature to obtain a phenolic resin adhesive.
[0064] Comparative Example 2
[0065] This comparative example provides a condensed tannin modified phenolic resin, and its preparation method is as follows:
[0066] 50 parts of phenol, 100 parts of water, 150 parts of formaldehyde solution, 62 parts of sodium hydroxide solution (40%) and 80 parts of condensed tannin are mixed, and then reacted at 90°C for 80 minutes; after adding 55 parts of formaldehyde solution (37%) and 13 parts of sodium hydroxide solution (40%), the mixture is kept warm and reacted at 90°C for 30-40 minutes. When the viscosity of the reaction system is measured by a grid tube and is 1.5-2s, the mixture is cooled to room temperature to obtain a condensed tannin-modified phenolic resin.
[0067] Test example
[0068] The phenolic resin adhesives prepared in the Examples and Comparative Examples were tested according to the national standard GB / T17657-2013. The results, shown in Table 1, demonstrate that the prepared modified phenolic resins exhibited fast curing speed, high water-resistant adhesive strength, and high toughness. Examples 1 to 6 varied the ratio of different materials to alter the amino content in the amino-containing phenolic resins, thereby regulating the molar ratio of the amino groups in the amino-containing phenolic resins to the aldehyde groups in the dialdehyde.
[0069] Table 1. Gel time, boiling water resistance bonding strength and adhesion function of different phenolic resin adhesives
[0070]
[0071] It can be seen from the experimental data in Table 1 that the modified phenolic resin of the present invention has a fast curing speed, excellent boiling water resistant bonding strength and bonding toughness. Compared with pure phenolic resin and condensed tannin modified phenolic resin, the gel time of the modified phenolic resin of the present invention is significantly shortened, with the maximum value reduced from 453s to 69s, and the improvement of boiling water resistant bonding performance and adhesion work under low temperature (110°C) hot pressing conditions is also significant, with the maximum improvement of 7.76 times and 1.08 times respectively. Importantly, the boiling water resistant bonding strength of the 110°C hot-pressed artificial board is as high as 1.84MPa, meeting the production requirements of Class I plywood (≥0.7MPa), showing excellent low-temperature fast curing characteristics.
[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.
Claims
1. A phenolic resin wood adhesive, characterized in that The invention comprises an amino phenolic resin and a dialdehyde, wherein the molar ratio of the primary amino group in the amino phenolic resin to the aldehyde group in the dialdehyde is 1:(1-2).
2. A phenolic resin wood adhesive according to claim 1, characterized in that: The structural formula of the amino phenolic resin is as follows:
3. The phenolic resin wood adhesive according to claim 1, characterized in that: The pH value is 3-6.
4. The phenolic resin wood adhesive according to claim 1, characterized in that: The amino phenolic resin is prepared by reacting thermoplastic phenolic resin with polyamine and formaldehyde through Mannich reaction.
5. A phenolic resin wood adhesive according to claim 4, characterized in that: The polyamine is one or both of diethylenetriamine and triethylenetetramine.
6. The phenolic resin wood adhesive according to claim 4, characterized in that: The average molecular weight of the thermoplastic phenolic resin is 500-2000 Da.
7. The phenolic resin wood adhesive according to claim 1, characterized in that: The dialdehyde is one or more of glyoxal, terephthalaldehyde and 2,5-furandicarboxaldehyde.
8. The phenolic resin wood adhesive according to claim 1, characterized in that: The dialdehyde and the amino phenolic resin solution are stirred and mixed to obtain a modified phenolic resin.
9. The phenolic resin wood adhesive according to claim 8, characterized in that: The structural formula of the modified phenolic resin is as follows:
10. The method for preparing a phenolic resin wood adhesive according to any one of claims 1 to 9, characterized in that: The steps include: Step (1): dissolving an amino phenolic resin in water, and then adjusting the pH value to obtain an amino phenolic resin solution; Step (2): adding dialdehyde to the amino phenolic resin solution, stirring and mixing to obtain a modified phenolic resin wood adhesive.