Epoxy Additives for Soy Protein Gum, Their Preparation Methods and Applications

Abstract

This invention provides an epoxy additive for soybean protein adhesive, its preparation method, and its application. The epoxy additive is mainly prepared by polymerization of the following raw materials in the specified molar proportions: 100 parts of trifunctional isocyanate and 295-305 parts of S-glycidyl ether. The soybean protein adhesive comprises the following raw materials in the specified weight proportions: 100 parts of polyamide polyamine-epoxychloropropane solution, 3-10 parts of glass microspheres, 5-10 parts of the epoxy additive according to any one of claims 1-3, and 30-38 parts of defatted soybean flour. The solid content of the polyamide polyamine-epoxychloropropane solution is 10-15%. The epoxy additive improves the crosslinking degree of the soybean protein adhesive by reacting its three epoxy functional groups with the amino and carboxyl groups in soybean protein, effectively increasing the bonding strength of the soybean protein adhesive and compensating for the reduction in bonding strength caused by the addition of glass microspheres. The addition of glass microspheres also effectively improves the sound insulation effect of plywood.

Description

Technical Field

[0001] This invention relates to the field of plywood, and more particularly to an epoxy additive for soybean protein adhesive, its preparation method, and its application. Background Technology

[0002] Plywood is an important branch of engineered wood products and the largest producer and seller among the three major types of wood products in the timber industry (plywood, particleboard, and fiberboard). The structural units of plywood are all rotary-cut veneers, which better preserve the physical and mechanical properties of the original wood. Plywood, made with adhesives, has a very wide range of applications, including decorative plywood, furniture plywood, decorative substrate plywood, structural plywood, shaped (irregular surface) plywood, shipbuilding plywood, aviation plywood, railway passenger car plywood, packaging box plywood, engineered wood flooring plywood, container flooring plywood, concrete formwork plywood, and even ping-pong paddle plywood, covering many industrial sectors including construction and transportation.

[0003] Most existing technologies use urea-formaldehyde resin and its modified products as adhesives, but urea-formaldehyde resin adhesives release formaldehyde, polluting the environment. While using biomass adhesives to prepare engineered wood products can solve the problem of free formaldehyde release, most biomass adhesives suffer from low bonding strength, poor water resistance, and high brittleness, limiting their industrial application. Furthermore, plywood preparation mainly includes processes such as veneer gluing, plywood assembly, pre-pressing (cold pressing), plywood repair, and hot pressing (gluing). If the cold pressing is ineffective, the plywood may crack, making repair and hot pressing impossible, requiring repeated cold pressing, resulting in low yield or reduced efficiency. Therefore, between veneer cold pressing and gluing, the cold-pressed plywood is left to stand for several hours to observe the cold pressing effect, reducing production costs.

[0004] To address this, Chinese invention patent application CN 113355049A discloses a tough soybean protein-based adhesive, comprising the following components by weight: 10-20 parts of a main agent, 2-4 parts of a crosslinking agent, and 2-3 parts of an epoxidized natural rubber hybrid material; wherein the main agent is soybean protein isolate; and the crosslinking agent is glycidyl amine. This soybean protein-based adhesive exhibits high bonding strength, good water resistance, low brittleness, and good toughness, meeting the water resistance and processing requirements of plywood adhesives. Furthermore, the soybean protein-based adhesive has a low cost, ensuring its practical performance. However, the soybean protein-based adhesive disclosed in the patent application is prone to blank breakage during cold pressing, especially for plywood used in bus floors, resulting in low yield or reduced efficiency. In addition, long-distance passenger buses travel at high speeds, and the use of plywood as the floorboard, coupled with the poor sound insulation of wood plywood, leads to significant noise inside the bus. Especially when the chassis is impacted by stones or other objects during operation, it generates considerable noise, which can affect passengers' mood and reduce their comfort. Summary of the Invention

[0005] In view of this, one objective of the present invention is to provide an epoxy additive for soybean protein adhesive and a method for preparing the same, so as to improve the initial tack performance of soybean protein adhesive and thereby improve the cold pressing performance of plywood.

[0006] Another objective of this invention is to provide a soybean protein adhesive using the aforementioned epoxy additive, its preparation method, and its application in plywood. The soybean protein adhesive contains hollow glass microspheres, which gives it higher initial bonding strength, improves the yield and production efficiency of plywood, and also significantly enhances the sound insulation effect of the plywood.

[0007] Therefore, the technical solution provided by the present invention is as follows:

[0008] An epoxy additive for soybean protein gum is mainly prepared by polymerization reaction of the following raw materials in the specified molar proportions: 100 parts of trifunctional isocyanate and 295-305 parts of S-glycidyl ether. In this way, the isocyanate groups in the trifunctional isocyanate and the OH groups in the S-glycidyl ether react almost completely to obtain a small-molecule epoxy additive containing three epoxy functional groups.

[0009] The trifunctional isocyanate is HDI biuret, HDI trimer, TDI trimer, or IPDI trimer.

[0010] Based on the above, the raw materials further include a solvent, which is 50% to 100% of the total mass of the trifunctional isocyanate and s-glycidyl. Preferably, the solvent is one or two of butyl acetate, butanone, toluene, and xylene.

[0011] Based on the above, the raw materials further include a catalyst, which is 0.003% to 0.01% of the total mass of the trifunctional isocyanate and s-glycidyl ether. Preferably, the catalyst is dibutyltin dilaurate or dibutyltin dichloro.

[0012] A method for preparing the above-mentioned epoxy auxiliary agent for soybean protein gum includes the following steps: a trifunctional isocyanate and s-glycidyl undergo a polymerization reaction in a nitrogen protective atmosphere.

[0013] The preparation method described above includes the following steps: in a nitrogen protective atmosphere, first reacting S-glycidyl ether and trifunctional isocyanate in a solvent; then, under stirring, adding a catalyst to continue the reaction, thereby obtaining the epoxy auxiliary agent.

[0014] Specifically, the preparation method of the epoxy additive for soybean protein gum includes the following steps: first, dissolve the small molecule S-glycidyl in a solvent and heat it to 55℃~65℃, then add isocyanate and react for 1~2h; then, under nitrogen protection and stirring at 40~60r / min, add a catalyst and continue the reaction for 3~5h to obtain the treatment agent.

[0015] A soybean protein gum comprises the following raw materials in parts by weight: 100 parts of polyamide polyamine-epoxychloropropane solution, 3-10 parts of glass microspheres, 5-10 parts of epoxy additives, and 30-38 parts of defatted soybean flour, wherein the solid content of the polyamide polyamine-epoxychloropropane solution is 10-15%.

[0016] Based on the above, the polyamide polyamine-epoxychloropropane solution is mainly prepared by reacting adipic acid, diethylenetriamine and epichlorohydrin in a molar ratio of 100:101-103:95-105.

[0017] Based on the above, the polyamide polyamine-epoxychloropropane solution is mainly prepared from the following raw materials: adipic acid, diethylenetriamine, epichlorohydrin, deionized water, and the above-mentioned epoxy additives. The mass of the deionized water is 7 times the total mass of adipic acid, diethylenetriamine, and epichlorohydrin to control the solid content of the polyamide polyamine-epoxychloropropane solution. The mass of the epoxy additives is 3-6% of the total mass of adipic acid, diethylenetriamine, and epichlorohydrin to improve the degree of crosslinking of the molecular chains and prevent non-crosslinking.

[0018] The polyamide polyamine-epoxychloropropane solution is mainly prepared by first reacting adipic acid with diethylenetriamine to synthesize polyamide polyamine, and then adjusting with deionized water to obtain a polyamide polyamine mixture with a solid content of 30%; then adding epoxy additives for reaction, adjusting the solid content with deionized water, and finally adding epichlorohydrin and adjusting the pH to 3.5.

[0019] Specifically, the polyamide polyamine-epoxychloropropane solution is prepared by the following method: adipic acid and diethylenetriamine are reacted at 180°C for 3 hours, then the temperature is lowered to 80°C and deionized water is added to adjust the solid content to 30%, then epoxy additives are added and reacted at 80°C for 1 hour, then the remaining deionized water is added, the temperature is lowered to room temperature, epichlorohydrin is added dropwise over 20 minutes, then the temperature is raised to 60°C and held for 60 minutes, and the pH is adjusted to 3.5 with hydrochloric acid.

[0020] The glass microspheres are hollow glass microspheres with a true density of 0.25–0.40 g / cm³. 3 The particle size D90 is 70-100μm, preferably HL32, HL35, or HL38 produced by Zhengzhou Shenglait Hollow Microsphere New Material Co., Ltd.

[0021] A method for preparing the above-mentioned soybean protein gum includes the following steps: uniformly mixing the above-mentioned polyamide polyamine-epoxychloropropane solution, glass microspheres, epoxy additives and defatted soybean powder.

[0022] A plywood blank includes wood veneer and an adhesive applied between the wood veneer, the adhesive being the aforementioned soybean protein adhesive.

[0023] A type of plywood is obtained by cold pressing and hot pressing of the aforementioned plywood blank. Specifically, the plywood blank is cold-pressed at a pressure of 0.8–1.2 MPa for 1–2 hours, and then hot-pressed at 1.0–1.3 MPa and 110–120°C for 5–12 minutes.

[0024] The epoxy additive for soybean protein adhesive provided by the present invention is a small molecule epoxy additive containing three epoxy functional groups. By reacting the epoxy functional groups with the amino and carboxyl groups in soybean protein, the crosslinking degree of soybean protein adhesive is improved. Thus, the epoxy additive can effectively improve the bonding strength of soybean protein adhesive and compensate for the problem of reduced bonding strength caused by the addition of glass microspheres.

[0025] The glass microspheres in the soybean protein adhesive provided by this invention can effectively improve the sound insulation effect of plywood. At the same time, the addition of the epoxy additive can compensate for the problem of reduced bonding strength caused by the addition of glass microspheres, so that the soybean protein adhesive has high bonding strength.

[0026] The polyamide polyamine-epoxychloropropane solution in soybean protein adhesive, due to the introduction of small-molecule epoxy additives containing three epoxy functional groups, increases the cross-linking degree of the resin matrix in the solution and improves its bulk viscosity. Therefore, soybean protein adhesive has a higher initial bonding strength, improves the cold pressing performance of plywood using soybean protein adhesive, and reduces or avoids phenomena such as blanking after cold pressing of the plywood blank, thereby improving the yield and production efficiency of plywood. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0028] Epoxy Additives

[0029] Examples 1-4 each provide an epoxy additive for soybean protein gum, which is mainly prepared by polymerization reaction of trifunctional isocyanate, s-glycidyl alcohol, solvent and catalyst. The molar ratio of trifunctional isocyanate to s-glycidyl alcohol is 1:3, the mass of the solvent is 75% of the total mass of trifunctional isocyanate and s-glycidyl alcohol, and the mass of the catalyst is 0.007% of the total mass of trifunctional isocyanate and s-glycidyl alcohol. The specific components of the trifunctional isocyanate, solvent and catalyst provided in each example are shown in Table 1 below.

[0030] Table 1 Raw Material List for Epoxy Additives

[0031] project Isocyanates S-glycidyl solvent catalyst Example 1 HDI biuret S-glycidyl Ethyl acetate Dibutyltin dilaurate Example 2 HDI trimer S-glycidyl Butanone Dibutyltin dilaurate Example 3 TDI trimer S-glycidyl Toluene Dichlorodibutyltin Example 4 IPDI trimer S-glycidyl xylene Dichlorodibutyltin

[0032] The preparation method of the epoxy additives provided in each embodiment is as follows: dissolve the S-glycidyl ether small molecule in a solvent, heat to 55℃~65℃, then add isocyanate and react for about 1.5h. Under nitrogen protection and stirring at 50r / min, add catalyst and continue the reaction for about 4h to obtain the small molecule epoxy additive containing 3 epoxy functional groups.

[0033] Soy protein gum

[0034] Examples 5-10 each provide a soybean protein gel, which is prepared by uniformly mixing the raw materials shown in Table 2.

[0035] Table 2. Proportioning of Soy Protein Gum Raw Material by Mass Component

[0036]

[0037] The polyamide polyamine-epoxychloropropane solutions A1 to A4 shown in Table 2 have a solid content of 12%, which are prepared by the following methods: 100 moles of adipic acid and 102 moles of diethylenetriamine are reacted at 180°C for 3 hours, then cooled to 80°C and deionized water is added to adjust the solid content to 30%. Then, the epoxy additives corresponding to each example are added and reacted at 80°C for 1 hour. Then, the remaining deionized water is added, the temperature is lowered to room temperature, and 100 moles of epichlorohydrin are added dropwise within 20 minutes. Then, the temperature is raised to 60°C and held for 60 minutes. The pH is adjusted to 3.5 with hydrochloric acid. The total mass of deionized water is 7 times the total mass of adipic acid, diethylenetriamine, and epichlorohydrin, and the corresponding mass of epoxy additives is 5% of the total mass of adipic acid, diethylenetriamine, and epichlorohydrin.

[0038] plywood blank

[0039] Each of the embodiments provides a plywood blank B1 to B6, comprising 5 poplar veneers and an adhesive applied between the poplar veneers. The adhesive is a soybean protein glue prepared from the raw materials shown in Table 2. Among them, B1 corresponds to Embodiment 5, B2 to Embodiment 6, B3 to Embodiment 7, B4 to Embodiment 8, B5 to Embodiment 9, and B6 to Embodiment 10.

[0040] The preparation method for each plywood blank is as follows: Soybean protein adhesive corresponding to each embodiment is evenly applied to one side of four poplar veneers (200g / m²). 2 Then, the plywood blank is made by assembling a veneer without soybean protein glue perpendicular to each other to form a 5-layer plywood blank, that is, there is a layer of soybean protein glue between every two layers of veneer.

[0041] plywood

[0042] Each embodiment provides a plywood C1 to C6, which is obtained by first cold pressing the plywood blanks provided in embodiments B1 to B6 at a pressure of about 1 MPa for about 1.5 hours, and then hot pressing at about 1.2 MPa and 110°C to 120°C for about 8 minutes; wherein, C1 corresponds to B1, C2 to B2, C3 to B3, C4 to B4, C5 to B5, and C6 to B6.

[0043] Comparative Example

[0044] The soybean protein adhesives D1-3 provided in the comparative examples are basically the same as those provided in Examples 5-7. The main difference is that the raw materials of soybean protein adhesives D1-3 do not contain glass microspheres or corresponding epoxy additives. The solid content of the polyamide polyamine-epoxychloropropane solution remains unchanged, and no corresponding epoxy additives are added during the preparation of the polyamide polyamine-epoxychloropropane solution. Everything else is the same.

[0045] The soybean protein adhesives D4-6 provided in the comparative examples are basically the same as those provided in Examples 5-7. The main difference is that the raw materials of soybean protein adhesives D4-6 do not contain the corresponding epoxy additives, the solid content of the polyamide polyamine-epoxychloropropane solution remains unchanged, and the corresponding epoxy additives are not added during the preparation of the polyamide polyamine-epoxychloropropane solution. Everything else is the same.

[0046] The soybean protein adhesives D7-9 provided in the comparative examples are basically the same as those provided in Examples 5-7. The main difference is that the solid content of the polyamide polyamine-epoxychloropropane solution in the raw materials of soybean protein adhesives D7-9 remains unchanged. At the same time, the total mass of epoxy additives in the raw materials is the same as that in the corresponding Examples 5-7. That is, no epoxy additives are added during the preparation of the polyamide polyamine-epoxychloropropane solution. The total mass of epoxy additives in Examples 5-7 also includes the epoxy additives added during the preparation of the polyamide polyamine-epoxychloropropane solution. Everything else is the same.

[0047] Comparative Examples 1 to 9 each provide a type of plywood, the main difference of which is that Comparative Examples 1 to 9 use soybean protein glue D7 to 9 instead of soybean protein glue in plywood C1 to C3.

[0048] Performance testing

[0049] The following performance verification tests were conducted on the soybean protein glue, plywood C1-C6, soybean protein glue D1-9 provided in Examples 5-10 and the plywood provided in Comparative Examples 1-9, and the results are shown in Table 3.

[0050] 1) Noise reduction test: First, prepare a 50cm*50cm*50cm square box from the plywood sample; then place an 80dB sound source in the square box and seal the seams of the box; then use a decibel meter to measure the decibel level from 1 meter away and record the data.

[0051] 2) Bonding strength test: Mechanical properties were tested according to standard GBT 9846-2015.

[0052] 3) Cold pressing condition: After cold pressing, lay flat for 6 hours and observe its condition.

[0053] Table 3 Properties of Soybean Protein Gum

[0054]

[0055] From Table 3, we can conclude that:

[0056] 1) According to the noise reduction rate calculation formula: (comparative example noise reduction test data - example example noise reduction test data) / (80 - comparative example noise reduction test data), the noise reduction data of comparative example 1 to plywood C1 (example 5), comparative example 2 to plywood C2 (example 6), and comparative example 3 to plywood C3 (example 7) were calculated respectively. The noise reduction rates were found to be 41.7%, 54.5%, and 50% respectively. It can be seen that the noise reduction rate of plywood will be increased by more than 40% after adding glass microspheres, which can effectively improve the sound insulation effect of plywood and improve the comfort of bus passengers.

[0057] 2) As can be seen from the bonding strength data of soybean protein glues D4, D5, D6 and Examples 5, 6 and 7, the epoxy additive of the present invention is beneficial to improving the strength of plywood;

[0058] 3) Explanation of the bonding strength data of soybean protein glue D7, D8, D9 and Examples 5, 6 and 7: The epoxy additives provided by this invention are beneficial to improving the cold pressing effect of plywood and increasing the yield and production efficiency of plywood when added to the synthesis process of polyamide polyamine-epoxychloropropane solution.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A soybean protein gum, characterized in that, The raw materials include the following parts by weight: 100 parts of polyamide polyamine-epoxychloropropane solution, 3-10 parts of glass microspheres, 5-10 parts of epoxy additive, and 30-38 parts of defatted soybean flour. The epoxy additive is mainly obtained by polymerization reaction of the following raw materials in the following molar proportions, which are mainly composed of 100 parts of trifunctional isocyanate and 295-305 parts of S-glycidyl. The polyamide polyamine-epoxychloropropane solution has a solid content of 10-15%. It is mainly produced by first reacting adipic acid with diethylenetriamine to synthesize polyamide polyamine, and then adjusting the solid content with deionized water to obtain a polyamide polyamine mixture with a solid content of 30%. Then, the epoxy auxiliary agent is added for further reaction, and the solid content is adjusted with deionized water. Epichlorohydrin is then added, and the pH is adjusted to 3.

5. The molar ratio of adipic acid, diethylenetriamine, and epichlorohydrin is 100:101-103:95-105. The mass of the additional epoxy auxiliary agent is 3-6% of the total mass of adipic acid, diethylenetriamine, and epichlorohydrin.

2. The soybean protein gum according to claim 1, characterized in that, The preparation method of the epoxy additive includes: reacting S-glycidyl ether and the trifunctional isocyanate in a solvent under a nitrogen protective atmosphere; and then adding a catalyst to continue the reaction under stirring.

3. The soybean protein gum according to claim 2, characterized in that, The amount of solvent used is 50% to 100% of the total mass of the trifunctional isocyanate and s-glycidyl.

4. The soybean protein gum according to claim 2, characterized in that, The catalyst is used at a rate of 0.003% to 0.01% of the total mass of the trifunctional isocyanate and s-glycidyl.

5. The soybean protein gum according to any one of claims 1-4, characterized in that, The mass of deionized water used in the preparation of the polyamide polyamine-epoxychloropropane solution is 7 times the total mass of adipic acid, diethylenetriamine, and epichlorohydrin.

6. A plywood blank, comprising wood veneer and an adhesive applied between the wood veneer, characterized in that: The adhesive is the soybean protein adhesive according to any one of claims 1 to 5.

7. A type of plywood, characterized in that: It is mainly produced by cold pressing the plywood blank as described in claim 6 under a pressure of 0.8~1.2MPa for 1~2h, followed by hot pressing under a pressure of 1.0~1.3MPa and a temperature of 110℃~120℃ for 5~12min.

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