Adhesive composition and its application in preparing reconstituted wood

Abstract

The present invention provides an adhesive composition, comprising a resin material modifier and a wood adhesive; the resin material modifier uses 3-chloro-2-hydroxy-propyl as a capping group, has a sulfur content of 5% to 60%, and a hydroxyl content of 1% to 10%. In the adhesive composition system of the present invention, a polythiol compound is used as a substrate, and 3-chloro-2-hydroxy-propyl is used as an end-capping group. By controlling the mutual restraint of sulfur content and hydroxyl content, the resin material modifier can achieve stable compatibility in a conventional wood glue system, while achieving a good level of dimensional stability for reconstituted wood substrates, excellent anti-aging performance, a thickness expansion rate of ≤3.5%, and a width expansion rate of less than or equal to 3%. The present invention also provides an application of the adhesive composition.

Description

Technical Field

[0001] The present invention belongs to the technical field of wood-based composite materials, and in particular relates to an adhesive composition and application thereof in the preparation of reconstituted wood. Background Art

[0002] High-performance reconstituted wood is a new type of high-performance natural polymer composite material made from plantation wood as raw material and cells as basic units, through directional reorganization and resin compounding. It can overcome the defects of plantation wood such as small diameter, soft material, low strength and uneven material. It has the characteristics of controllable performance, designable structure and adjustable specifications. It is one of the effective ways to make good use of small materials and inferior materials, and is one of the frontiers and hot spots of research in the field of natural polymer materials.

[0003] The huge challenges faced by reconstructed wood come from the bonding strength and the deterioration of dimensional stability and even expansion and cracking when exposed to water after reconstructing.

[0004] In response to this challenge, many solutions have been reported in the literature. For example, CN101357470 improves the bonding strength by loosening the veneer, improving the crack uniformity of the wood bundles and improving the uniformity of the impregnation. Although it has a certain effect in comparison, the internal bonding strength is still relatively low, less than 2 MPa, and a good effect is not achieved. CN111171770 uses a synergistic silicon-modified phenolic resin to effectively improve the internal bonding strength and saturated water absorption rate of the reconstituted wood (internal bonding strength 3.0-5.0 MPa, saturated water absorption rate 12.5-14.9%). This existing technology uses the addition of organic salts for modification, which has the defects of poor compatibility or even incompatibility with the phenolic adhesive system, seriously undermining the stability of the phenolic adhesive system, causing great passivity in large-scale production and use, and difficult to apply. Summary of the Invention

[0005] The purpose of the present invention is to provide an adhesive composition and its use in the preparation of reconstituted wood. The resin material modifier in the present invention can achieve stable compatibility in conventional wood glue systems and at the same time make the dimensional stability of the reconstituted wood substrate reach a good level.

[0006] The present invention provides an adhesive composition comprising a resin material modifier and a wood adhesive;

[0007] The resin material modifier uses 3-chloro-2-hydroxy-propyl as the end-capping group, has a sulfur content of 5 to 60 wt%, and a hydroxyl content of 1 to 10 wt%.

[0008] Preferably, the resin material modifier has a structure shown in Formula I:

[0009]

[0010] R is a polythiol compound, 1≤n≤4.

[0011] Preferably, the R has a structure represented by any one of R-1 to R-22:

[0012]

[0013]

[0014] Preferably, the resin material modifier contains 14-40% sulfur and 5-10% hydroxyl groups.

[0015] Preferably, the adhesive composition contains 15 to 30% glue.

[0016] Preferably, the wood adhesive is phenolic resin.

[0017] Preferably, the mass ratio of the resin material modifier to the wood adhesive is (0.05-50):100.

[0018] The present invention provides a use of the resin material modifier as described above in preparing reconstituted wood. The resin material modifier is mixed with a wood adhesive and used as an adhesive to prepare the reconstituted wood.

[0019] Preferably, the preparation of the recombinant wood comprises the following steps:

[0020] The veneer is sequentially impregnated with glue, pressed and cured at high temperature to obtain reconstituted wood.

[0021] Preferably, the high temperature curing adopts the following temperature raising program: 90-110° C. for 0.5-1.5 hours; 110-130° C. for 1.5-2.5 hours; and 130-150° C. for 3-5 hours.

[0022] The present invention provides an adhesive composition comprising a resin material modifier and a wood adhesive. The resin material modifier uses 3-chloro-2-hydroxy-propyl as an end-capping group, has a sulfur content of 5% to 60%, and a hydroxyl content of 1% to 10%. In the adhesive composition system of the present invention, a polythiol compound is used as a base, and 3-chloro-2-hydroxy-propyl is used as an end-capping group. By controlling the sulfur content and the hydroxyl content, the resin material modifier can achieve stable compatibility in conventional wood glue systems, while also achieving good dimensional stability with reconstituted wood substrates, excellent aging resistance, a thickness expansion ratio of ≤3.5%, and a width expansion ratio of ≤3%.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The substrate has strong applicability and the resin modifier has good compatibility when added to conventional wood adhesive systems;

[0025] (2) The composition containing the modifier has excellent mechanical properties and dimensional stability in the application of reconstituted wood. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0027] Figure 1 Fluorescence microscope pictures of the dipped veneers in Example 1, Example 2, Example 5 and Comparative Example 1 of the present invention;

[0028] Figure 2 This is the liquid phase spectrum of the resin material modifier with 3-chloro-2-hydroxy-propyl as the end-capping group in Example 1;

[0029] Figure 3 The Raman spectrum of the raw material 2,3-bis(2-mercaptoethylthio)-3-propane-1-thiol;

[0030] Figure 4 This is the Raman spectrum of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane. DETAILED DESCRIPTION

[0031] The present invention provides an adhesive composition comprising a resin material modifier and a wood adhesive;

[0032] The resin material modifier adopts 3-chloro-2-hydroxy-propyl as the end-capping group, has a sulfur content of 5% to 60%, and a hydroxyl content of 1% to 10%.

[0033] In the present invention, the resin material modifier has a structure shown in Formula I:

[0034]

[0035] R is a polythiol compound, 1≤n≤4, such as n is 1, 2, 3 or 4. Preferably, R has a structure represented by any one of R-1 to R-22:

[0036]

[0037]

[0038] In the present invention, the sulfur content in the resin material modifier is preferably 5-60%, more preferably 10-55%, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, preferably a range value with any of the above values ​​as the upper or lower limit; the hydroxyl content in the resin material modifier is preferably 1-10%, more preferably 3-8%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0039] In the present invention, the resin material modifier is preferably prepared according to the following steps:

[0040] After the polythiol monomer and methanol are stirred evenly, epichlorohydrin is added, and after stirring evenly, an alkaline catalyst is added dropwise to react. The reaction end point is determined by high performance liquid chromatography content. When the content of the polythiol monomer is less than 3%, it is the end point. The solvent is removed by a rotary evaporator to obtain a resin material modifier.

[0041] In the present invention, the molar ratio of the polythiol monomer to epichlorohydrin is preferably 1:(1-4), such as 1:1, 1:2, 1:3, 1:4, preferably a range value with any of the above values ​​as the upper or lower limit.

[0042] In the present invention, the reaction temperature is preferably -15 to 65°C, more preferably 0 to 45°C, such as -15°C, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, preferably a range value with any of the above numerical values ​​as the upper or lower limit; the reaction time is preferably 2 to 24 hours, more preferably 6 to 20 hours, and most preferably 10 to 15 hours.

[0043] In the present invention, the wood adhesive is a common wood adhesive in the art. The resin material modifier substrate in the present invention has strong applicability and good compatibility when added to a conventional wood adhesive system. Therefore, the present invention does not impose any special restrictions on the type of wood adhesive. Specifically, in an embodiment of the present invention, a phenolic resin adhesive can be used.

[0044] In the present invention, the mass ratio of the resin material modifier to the wood adhesive is preferably (0.05-50):100, more preferably (1-40):100, such as 0..05:100, 1:100, 5:100, 10:100, 15:100, 20:100, 25:100, 30:100, 35:100, 40:100, 45:100, 50:100, preferably a range value with any of the above values ​​as the upper or lower limit. When the content of the resin material modifier is low, the grid structure formed in the system is small, and the effect on the stability of the reconstituted wood substrate is not obvious. When the content of the resin material modifier is too high, there is a risk of poor stability of the adhesive system, which causes passivity in large-scale production and has no obvious effect on improving dimensional stability.

[0045] In the present invention, the adhesive composition preferably contains 10-30% glue, more preferably 20%.

[0046] The present invention also provides a use of the resin material modifier described above in preparing reconstituted wood. The resin material modifier described above is mixed with a wood adhesive and used as an adhesive to prepare the reconstituted wood.

[0047] Specifically, the veneer is dipped in adhesive, and then pressed and cured at high temperature in sequence to obtain reconstituted wood.

[0048] In the present invention, the types and amounts of the resin material modifier and the wood adhesive are consistent with those described above, and the present invention will not elaborate on them here.

[0049] In the present invention, the impregnation and pressing are both commonly used processes for preparing reconstituted wood in the art, and the present invention will not elaborate on them here.

[0050] In the present invention, the high temperature curing is preferably carried out by programmed temperature rise, specifically, first maintaining the temperature at 90-110°C for 0.5-1.5 hours; then maintaining the temperature at 110-130°C for 1.5-2.5 hours, and finally maintaining the temperature at 130-150°C for 3-5 hours, more preferably, maintaining the temperature at 100°C for 1 hour; then maintaining the temperature at 120°C for 2 hours, and finally maintaining the temperature at 140°C for 4 hours, so as to achieve a core layer temperature of 120°C for 2 hours, and then cooling and opening the mold to obtain the reconstituted wood.

[0051] The present invention provides an adhesive composition comprising a resin material modifier and a wood adhesive. The resin material modifier uses 3-chloro-2-hydroxy-propyl as an end-capping group, has a sulfur content of 5% to 60%, and a hydroxyl content of 1% to 10%. In the adhesive composition system of the present invention, a polythiol compound is used as a base, and 3-chloro-2-hydroxy-propyl is used as an end-capping group. By controlling the sulfur content and the hydroxyl content, the resin material modifier can achieve stable compatibility in conventional wood glue systems, while also achieving good dimensional stability with reconstituted wood substrates, excellent aging resistance, a thickness expansion ratio of ≤3.5%, and a width expansion ratio of ≤3%.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) The substrate has strong applicability and the resin modifier has good compatibility when added to conventional wood adhesive systems;

[0054] (2) The composition containing the modifier has excellent mechanical properties and dimensional stability in the application of reconstituted wood.

[0055] To further illustrate the present invention, an adhesive composition provided by the present invention and its application in the preparation of reconstituted wood are described in detail below with reference to examples, but these examples should not be construed as limiting the scope of protection of the present invention.

[0056] The phenolic adhesives for the wood industry used in the following examples and comparative examples are all from the same batch of the same manufacturer.

[0057] Example 1

[0058] Preparation of biomass recombinant 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane:

[0059] Weigh 130.5 g of 2,3-bis(2-mercaptoethylthio)-3-propane-1-thiol and 460 g of methanol solvent, stir evenly, add 166.7 g of epichlorohydrin, continue stirring evenly, add 6 g of 2% aqueous sodium hydroxide solution while stirring, control the reaction system to 0° C., the reaction time is 20 hours, and the reaction end point is determined by high performance liquid chromatography content. The end point is when the content of 2,3-bis(2-mercaptoethylthio)-3-propane-1-thiol is less than 3%. The solvent is removed by rotary evaporator to obtain 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane.

[0060] The preparation steps of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive are as follows:

[0061] (a) 6 g of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane and 36 g of ethanol were added to a reaction vessel and mixed for 30 min;

[0062] (b) adding 40g of phenolic adhesive for wood industry and mixing for 30min in step (a);

[0063] (c) adding 18 g of water to step (b) and diluting the mixture to a glue content of 26.4% to obtain 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive.

[0064] The steps for preparing recombinant wood are as follows:

[0065] (a) 1.2 kg of veneer was placed in a 10 L reactor and vacuumed to -0.4 MPa for 0.5 h.

[0066] (b) 10 kg of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive was added to the reactor and impregnated at a positive pressure of 0.6 MPa for 1 h;

[0067] (c) The wood in the reactor was removed and subjected to a process of extrusion-leach-extrusion for a total of 4-5 minutes, followed by air-drying for 24 hours;

[0068] (d) The impregnated veneer was cured by cold pressing to prepare reconstituted wood. The temperature was programmed to cure at 100°C for 1 hour, 120°C for 2 hours, and 140°C. The core temperature was tested to be 120°C and maintained for 2 hours.

[0069] Example 2

[0070] The preparation method of the biomass recombinant 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane is the same as that in Example 1.

[0071] The preparation steps of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive are as follows:

[0072] (a) 2 g of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane and 36 g of ethanol were added to a reaction vessel and mixed for 30 min;

[0073] (b) adding 40g of phenolic adhesive for wood industry and mixing for 30min in step (a);

[0074] (c) adding 22 g of water to step (b) and diluting the mixture to a glue content of 22.4% to obtain 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive.

[0075] The steps for preparing recombinant wood are as follows:

[0076] (a) Add 1.2 kg of veneer to a 10 L reactor;

[0077] (b) adding 10 kg of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive to the reactor, keeping the veneer completely below the liquid level, and maintaining immersion for 24 hours until the veneer is completely soaked;

[0078] (c) The wood in the reactor was removed and subjected to a process of extrusion-leach-extrusion for a total of 4-5 minutes, followed by air-drying for 24 hours;

[0079] (d) The impregnated veneer was cured by cold pressing to prepare reconstituted wood. The temperature was programmed to cure at 100°C for 1 hour, 120°C for 2 hours, and 140°C. The core temperature was tested to be 120°C and maintained for 2 hours.

[0080] Example 3

[0081] The preparation method of the biomass recombinant 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane is the same as that in Example 1.

[0082] The preparation steps of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive are as follows:

[0083] (a) 1 g of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane and 36 g of ethanol were added to a reaction vessel and mixed for 30 min;

[0084] (b) adding 40g of phenolic adhesive for wood industry and mixing for 30min in step (a);

[0085] (c) adding 23 g of water to step (b) and diluting the mixture to a glue content of 21.4% to obtain 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive.

[0086] The steps for preparing recombinant wood are as follows:

[0087] (a) 1.2 kg of veneer was placed in a 10 L reactor and vacuumed to -0.4 MPa for 0.5 h.

[0088] (b) 10 kg of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive was added to the reactor and impregnated at a positive pressure of 0.6 MPa for 1 h;

[0089] (c) The wood in the reactor was removed and subjected to a process of extrusion-leach-extrusion for a total of 4-5 minutes, followed by air-drying for 24 hours;

[0090] (d) The impregnated veneer is cured by hot pressing to prepare reconstituted wood. The temperature is programmed to cure at 100°C for 1 hour, 120°C for 2 hours, and 140°C. The core temperature is tested to be 120°C and maintained for 2 hours.

[0091] Example 4

[0092] The preparation method of the biomass recombinant 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane is the same as that in Example 1.

[0093] The preparation steps of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive are as follows:

[0094] (a) 0.5 g of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane and 36 g of ethanol were added to a reaction vessel and mixed for 30 min;

[0095] (b) adding 40g of phenolic adhesive for wood industry and mixing for 30min in step (a);

[0096] (c) adding 23.5 g of water to step (b) and diluting the mixture to a glue content of 20.9% to obtain 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive.

[0097] The steps for preparing recombinant wood are as follows:

[0098] (a) 1.2 kg of veneer was placed in a 10 L reactor and vacuumed to -0.4 MPa for 0.5 h.

[0099] (b) 10 kg of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive was added to the reactor and impregnated at a positive pressure of 0.6 MPa for 1 h;

[0100] (c) The wood in the reactor was removed and subjected to a process of extrusion-leach-extrusion for a total of 4-5 minutes, followed by air-drying for 24 hours;

[0101] (d) The impregnated veneer was cured by cold pressing to prepare reconstituted wood. The temperature was programmed to cure at 100°C for 1 hour, 120°C for 2 hours, and 140°C. The core temperature was tested to be 120°C and maintained for 2 hours.

[0102] Example 5

[0103] Preparation of biomass reconstituted agent 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-3-propane-1-thiol

[0104] Weigh 130.5 g of 2,3-bis(2-mercaptoethylthio)-3-propane-1-thiol and 460 g of methanol solvent, stir evenly, add 111.1 g of epichlorohydrin, continue stirring evenly, add 4.8 g of 2% aqueous sodium hydroxide solution while stirring, control the system to react at 15 ° C, the reaction time is 20 hours, and the reaction end point is determined by high performance liquid chromatography content. The end point is when the content of 2,3-bis(2-mercaptoethylthio)-3-propane-1-thiol is less than 3%. The solvent is removed by rotary evaporator to obtain 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane.

[0105] The preparation steps of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive are as follows:

[0106] (a) 2 g of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane and 36 g of ethanol were added to a reaction vessel and mixed for 30 min;

[0107] (b) adding 40g of phenolic adhesive for wood industry and mixing for 30min in step (a);

[0108] (c) adding 22 g of water to step (b) and diluting the mixture to a glue content of 22.4% to obtain 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive.

[0109] The steps for preparing recombinant wood are as follows:

[0110] (a) 1.2 kg of veneer was placed in a 10 L reactor and vacuumed to -0.4 MPa for 0.5 h.

[0111] (b) 10 kg of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive was added to the reactor and impregnated at a positive pressure of 0.6 MPa for 1 h;

[0112] (c) The wood in the reactor was removed and subjected to a process of extrusion-leach-extrusion for a total of 4-5 minutes, followed by air-drying for 24 hours;

[0113] (d) The impregnated veneer was cured by cold pressing to prepare reconstituted wood. The temperature was programmed to cure at 100°C for 1 hour, 120°C for 2 hours, and 140°C. The core temperature was tested to be 120°C and maintained for 2 hours.

[0114] Example 6

[0115] The preparation process of the biomass recombinant 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-3-propane-1-thiol is as shown in Example 3.

[0116] The preparation steps of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive are as follows:

[0117] (a) 1 g of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane and 36 g of ethanol were added to a reaction vessel and mixed for 30 min;

[0118] (b) adding 40g of phenolic adhesive for wood industry and mixing for 30min in step (a);

[0119] (c) adding 23 g of water to step (b) and diluting the mixture to a glue content of 21.4% to obtain 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive.

[0120] The steps for preparing recombinant wood are as follows:

[0121] (a) 1.2 kg of veneer was placed in a 10 L reactor and vacuumed to -0.4 MPa for 0.5 h.

[0122] (b) 10 kg of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive was added to the reactor and impregnated at a positive pressure of 0.6 MPa for 1 h;

[0123] (c) The wood in the reactor was removed and subjected to a process of extrusion-leach-extrusion for a total of 4-5 minutes, followed by air-drying for 24 hours;

[0124] (d) The impregnated veneer is cured by hot pressing to prepare reconstituted wood. The temperature is programmed to cure at 100°C for 1 hour, 120°C for 2 hours, and 140°C. The core temperature is tested to be 120°C and maintained for 2 hours.

[0125] Example 7

[0126] Preparation of biomass reconstituted agent 2,2'-bis(2-(3-chloro-2-hydroxy-propylthio)ethyl sulfide

[0127] Weigh 154.3 g of thiodiglycol mercaptan and 460 g of methanol solvent, stir evenly, add 203.5 g of epichlorohydrin, continue stirring evenly, add 7.2 g of 2% aqueous sodium hydroxide solution while stirring, control the reaction system to 0 ° C, the reaction time is 20 hours, and the reaction end point is determined by high performance liquid chromatography content. When the content of thiodiglycol mercaptan is less than 3%, it is the end point. The solvent is removed by rotary evaporator to obtain 2,2'-bis(2-(3-chloro-2-hydroxy-propylthio)ethyl sulfide.

[0128] The preparation steps of 2,2'-bis(2-(3-chloro-2-hydroxy-propylthio)ethyl sulfide modified wood industry adhesive are as follows:

[0129] (a) 4 g of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane and 36 g of ethanol were added to a reaction vessel and mixed for 30 min;

[0130] (b) adding 40g of phenolic adhesive for wood industry and mixing for 30min in step (a);

[0131] (c) adding 20 g of water to step (b) and diluting the mixture to a glue content of 24.4% to obtain 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive.

[0132] The steps for preparing recombinant wood are as follows:

[0133] (a) 1.2 kg of veneer was placed in a 10 L reactor and vacuumed to -0.4 MPa for 0.5 h.

[0134] (b) 10 kg of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive was added to the reactor and impregnated at a positive pressure of 0.6 MPa for 1 h;

[0135] (c) The wood in the reactor was removed and subjected to a process of extrusion-leach-extrusion for a total of 4-5 minutes, followed by air-drying for 24 hours;

[0136] (d) The impregnated veneer was cured by cold pressing to prepare reconstituted wood. The temperature was programmed to cure at 100°C for 1 hour, 120°C for 2 hours, and 140°C. The core temperature was tested to be 120°C and maintained for 2 hours.

[0137] Example 8

[0138] Preparation of biomass recombinant 3,3'-thiobis(1-(2-(3-chloro-2-hydroxy-propyl)thioethyl)-2,2'-bis(3-chloro-2-hydroxy-propyl)thiopropyl sulfide:

[0139] Weigh 183.4 g of 3,3'-thiobis(1-(2-mercaptoethyl)thiopropane)-2,2'-dimercaptan and 408 g of methanol as solvent, stir evenly, add 222.1 g of epichlorohydrin, continue stirring evenly, add 8.1 g of 2% aqueous sodium hydroxide solution while stirring, control the reaction system to 0° C., the reaction time is 20 hours, and the reaction end point is determined by high performance liquid chromatography content. The end point is when the content of 3,3'-thiobis(1-(2-mercaptoethyl)thiopropane)-2,2'-dimercaptan is less than 3%. The solvent is removed on a rotary evaporator to obtain 3,3'-thiobis(1-(2-(3-chloro-2-hydroxy-propyl)thioethyl)-2,2'-bis(3-chloro-2-hydroxy-propyl)thiopropyl sulfide.

[0140] The preparation steps of 3,3'-thiobis(1-(2-(3-chloro-2-hydroxy-propyl)thioethyl)-2,2'-bis(3-chloro-2-hydroxy-propyl)thiopropyl sulfide modified phenolic adhesive for wood industry are as follows:

[0141] (a) 2 g of 3,3'-thiobis(1-(2-(3-chloro-2-hydroxy-propyl)thioethyl)-2,2'-bis(3-chloro-2-hydroxy-propyl)thiopropyl sulfide was dissolved in 36 g of ethanol and uniformly dissolved, and the mixture was added to a reactor;

[0142] (b) adding 40g of phenolic adhesive for wood industry and mixing for 30min in step (a);

[0143] (c) adding 22 g of water to the mixture in step (b) to dilute the mixture to a glue content of 22.4% to obtain 3,3'-thiobis(1-(2-(3-chloro-2-hydroxy-propyl)thioethyl)-2,2'-bis(3-chloro-2-hydroxy-propyl)thiopropyl sulfide-modified phenolic adhesive for the wood industry.

[0144] The steps for preparing recombinant wood are as follows:

[0145] (a) 1.2 kg of veneer was placed in a 10 L reactor and vacuumed to -0.4 MPa for 0.5 h.

[0146] (b) 10 kg of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane modified wood industry adhesive was added to the reactor and impregnated at a positive pressure of 0.6 MPa for 1 h;

[0147] (c) The wood in the reactor was removed and subjected to a process of extrusion-leach-extrusion for a total of 4-5 minutes, followed by air-drying for 24 hours;

[0148] (d) The impregnated veneer is cured by hot pressing to prepare reconstituted wood. The temperature is programmed to cure at 100°C for 1 hour, 120°C for 2 hours, and 140°C. The core temperature is tested to be 120°C and maintained for 2 hours.

[0149] Comparative Example 1

[0150] The preparation steps of phenolic adhesive for wood industry are as follows:

[0151] 40 g of phenolic adhesive for wood industry and 60 g of water were added into a reaction kettle and mixed and diluted to a glue content of 22.4%, thereby obtaining phenolic adhesive for wood industry.

[0152] The steps to reconstruct wood are as follows:

[0153] (a) 1.2 kg of veneer was placed in a 10 L reactor and vacuumed to -0.4 MPa for 0.5 h.

[0154] (b) adding 10 kg of industrial phenolic glue having a solid content of 22.4% into the reaction kettle and subjecting it to positive pressure immersion at 0.6 MPa for 1 hour;

[0155] (c) The wood in the reactor was removed and subjected to a process of extrusion-leach-extrusion for a total of 4-5 minutes, followed by air-drying for 24 hours;

[0156] (d) The impregnated veneer was cured by cold pressing to prepare reconstituted wood. The temperature was programmed to cure at 100°C for 1 hour, 120°C for 2 hours, and 140°C. The core temperature was tested to be 120°C and maintained for 2 hours.

[0157] Comparative Example 2

[0158] The preparation steps of phenolic adhesive for wood industry are as follows:

[0159] 40 g of phenolic adhesive for wood industry and 60 g of water were added into a reaction kettle and mixed and diluted to a glue content of 22.4%, thereby obtaining phenolic adhesive for wood industry.

[0160] The steps to reconstruct wood are as follows:

[0161] (a) Add 1.2 kg of veneer to a 10 L reactor;

[0162] (b) adding 10 kg of industrial phenolic glue with a solid content of 22.4% into the reaction kettle and maintaining complete immersion for 24 hours until the veneer is completely soaked;

[0163] (c) The wood in the reactor was removed and subjected to a process of extrusion-leach-extrusion for a total of 4-5 minutes, followed by air-drying for 24 hours;

[0164] (d) The impregnated veneer is cured by hot pressing to prepare reconstituted wood. The temperature is programmed to cure at 100°C for 1 hour, 120°C for 2 hours, and 140°C. The core temperature is tested to be 120°C and maintained for 2 hours.

[0165] Comparative Example 3

[0166] Preparation of biomass reconstituted tris(3-chloro-2-hydroxy-propyl) trifunctional polyether polysulfide:

[0167] Weigh 130.5 g of trifunctional polyether polythiol and 460 g of methanol solvent, stir evenly, add 59.12 g of epichlorohydrin, continue stirring evenly, add 3.8 g of 2% sodium hydroxide aqueous solution while stirring, control the system to react at 0°C, the reaction time is 20 hours, and the reaction end point is determined by gas chromatography content. When the epichlorohydrin content is less than 3.5%, it is the end point. The solvent is removed by rotary evaporator to obtain tri(3-chloro-2-hydroxy-propyl) trifunctional polyether polysulfide (hydroxyl content is 10.7%, sulfur content is 9.48%).

[0168] The preparation steps of tris(3-chloro-2-hydroxy-propyl) trifunctional polyether polysulfide modified wood industry adhesive are as follows:

[0169] (a) 6 g of tris(3-chloro-2-hydroxy-propyl) trifunctional polyether polysulfide and 36 g of ethanol were added to a reaction kettle and mixed for 30 min;

[0170] (b) adding 40 g of wood industry adhesive to step (a) and mixing for 30 min;

[0171] (c) adding 18 g of water to the mixture in step (b) to dilute the mixture to obtain a tris(3-chloro-2-hydroxy-propyl) trifunctional polyether polysulfide-modified wood industry adhesive.

[0172] The steps for preparing recombinant wood are as follows:

[0173] (a) 1.2 kg of veneer was placed in a 10 L reactor and vacuumed to -0.4 MPa for 0.5 h.

[0174] (b) adding 10 kg of tris(3-chloro-2-hydroxy-propyl) trifunctional polyether polysulfide modified wood industry adhesive into the reactor and performing positive pressure impregnation at 0.6 MPa for 1 h;

[0175] (c) The wood in the reactor was removed and subjected to a process of extrusion-leach-extrusion for a total of 4-5 minutes, followed by air-drying for 24 hours;

[0176] (d) The impregnated veneer was cured by cold pressing to prepare reconstituted wood. The temperature was programmed to cure at 100°C for 1 hour, 120°C for 2 hours, and 140°C. The core temperature was tested to be 120°C and maintained for 2 hours.

[0177] The properties of the reconstituted wood prepared with the thiol-modified wood industrial adhesive provided in Examples 1 to 8 and Comparative Examples 1 to 3 were tested respectively; the internal bond strength was tested using a 3365 universal tensile testing machine from Instron, USA; 28h cyclic cracking evaluation: using the American Association's performance evaluation standard for Class I plywood, the sample was boiled in water at 100°C for 4h, oven-dried at 63°C for 20h, and boiled in water at 100°C for 4h, and the cracking of the sample was observed; no cracking was considered acceptable; anti-aging performance was tested using a BD / ZN-P ultraviolet lamp from Zhongkeboda Technology Co., Ltd.; the results of the various performance tests are shown in Table 1.

[0178] Table 1 Performance data of reconstituted wood prepared with the thiol-modified wood industrial adhesive provided in Examples 1-8 and Comparative Example 1

[0179]

[0180]

[0181] As can be seen from Table 1, the reconstituted wood prepared by the reconstituted agent-modified wood industrial adhesive provided in Examples 1 to 8 of the present invention has excellent mechanical properties and also better anti-aging properties.

[0182] In order to further analyze the excellent performance of reconstituted wood glue prepared by reconstituted wood glue, the distribution of phenolic glue in the veneer of different embodiments was detected and tracked using a Zeiss Axio Scope A1 fluorescence microscope. The results are as follows: Figure 1 .

[0183] Figure 1 In the figure, a, b, c and d are fluorescence analysis comparisons of the dipped veneer of Example 1, Example 2, Example 5 and Comparative Example 1 respectively. Figure 1 It can be seen that after modification with the resin material modifier, the phenolic adhesive is more evenly distributed in the veneer (the bright fluorescent spots are phenolic adhesive).

[0184] Figure 2 This is the liquid column chromatography analysis spectrum of the resin material modifier in Example 1. Through liquid column chromatography analysis and methanol-acid water 32:68 gradient separation, it was determined that the peak of the resin material modifier product with 3-chloro-2-hydroxy-propyl as the end group was concentrated at 14.4~15.13min, and the normalized content was 72-78%.

[0185] Figure 3 The Raman spectrum of the raw material 2,3-bis(2-mercaptoethylthio)-3-propane-1-thiol is Figure 4 The Raman spectrum of 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane. Figure 3、 Figure 4 Raman spectrum analysis showed that the thiol peak at 2556.74 cm-1 of the resin material modifier 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane completely disappeared, indicating that the thiol reaction in the product was complete.

[0186] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An adhesive composition comprising a resin material modifier and a wood adhesive; The resin material modifier is 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-1-(3-chloro-2-hydroxy-propyl)thiopropane, 2,3-bis(2-(3-chloro-2-hydroxy-propylthio)ethylthio)-3-propane-1-thiol, 2,2'-bis(2-(3-chloro-2-hydroxy-propylthio)ethyl sulfide or 3,3'-thiobis(1-(2-(3-chloro-2-hydroxy-propyl)thioethyl)-2,2'-bis(3-chloro-2-hydroxy-propyl)thiopropyl sulfide; The wood adhesive is phenolic resin.

2. The adhesive composition according to claim 1, characterized in that The adhesive composition contains 15-30% glue.

3. The adhesive composition according to claim 1, characterized in that The mass ratio of the resin material modifier to the wood adhesive is (0.05-50):

100.

4. A use of the resin material modifier as claimed in claim 1 in the preparation of reconstituted wood, wherein the resin material modifier is mixed with a wood adhesive and used as an adhesive to prepare the reconstituted wood.

5. The use according to claim 4, characterized in that The preparation of the recombinant wood comprises the following steps: The veneer is sequentially impregnated with glue, pressed and cured at high temperature to obtain reconstituted wood.

6. The use according to claim 5, characterized in that The high temperature curing adopts the following program heating: 90-110° C. for 0.5-1.5 hours; 110-130° C. for 1.5-2.5 hours; and 130-150° C. for 3-5 hours.

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