Non-grain grease-based formaldehyde-free adhesive as well as preparation method and application thereof

Abstract

The invention provides a non-grain oil-based formaldehyde-free adhesive as well as a preparation method and application thereof. The non-grain oil-based formaldehyde-free adhesive comprises the following components in parts by weight: 48-55 parts of an oil refining byproduct, 25-32 parts of a modifier, 0.8-1.8 parts of a catalyst, 10-20 parts of a cross-linking agent, 2 parts of butanone peroxide and 3-8 parts of isocyanate. According to the preparation method, vegetable fat refining by-products are used as raw materials and activated through transesterification, and the cross-linking agent and isocyanate are introduced for modification, so that the bonding strength and water resistance of the adhesive are remarkably improved. The obtained product can be used for preparing poplar plywood, and has the characteristics of no formaldehyde release, excellent environment friendliness and the like. According to the invention, a new way is provided for high-value utilization of grease byproducts, and the prepared adhesive also meets the use requirements of artificial board production in the aspect of performance.

Description

Technical Field

[0001] This invention relates to the field of adhesive preparation technology, and in particular to a non-grain oil-based formaldehyde-free adhesive, its preparation method, and its application. Background Technology

[0002] Plywood is a multi-layered sheet material made by rotary cutting logs into veneers or slicing timber into thin sheets, and then gluing them together with adhesives. Plywood possesses excellent characteristics such as high dimensional stability, uniform physical and mechanical properties, and low deformation rate. The industrial production of this material can be traced back to the early 20th century, and its development has been closely dependent on the invention of the rotary cutting machine and the application of phenolic resin adhesives. These key technological innovations not only solved the problem of efficient veneer preparation but also significantly improved the product's water resistance and structural strength, expanding its application from indoor furniture to construction formwork, shipbuilding, and even aerospace engineering fields.

[0003] However, traditional plywood technology still has significant limitations: its interlayer bonding reliability is easily degraded in humid, dry, or drastically temperature-sensitive environments due to uneven adhesive application or environmental stress, leading to delamination or separation, making it difficult to meet the stringent long-term service requirements of high-end applications. Furthermore, environmental and process issues are also limiting factors; traditional urea-formaldehyde resin plywood releases formaldehyde, posing a potential threat to the indoor environment and human health. Although there has been progress in the development of environmentally friendly adhesives, these adhesives generally face the challenge of balancing high cost and poor weather resistance, while energy consumption and waste utilization in the production process also need optimization. Therefore, given the increasingly stringent requirements for material performance and the growing acceptance of green manufacturing concepts, breaking through existing technological bottlenecks through material innovation and structural design improvements has become an urgent need for the development of this field.

[0004] On the other hand, the oil refining industry generates a large number of complex byproducts. These byproducts contain valuable active ingredients such as free fatty acids, phospholipids, and sterols, but also impurities, moisture, and pollutants. Improper disposal of these byproducts not only wastes resources but also poses environmental pollution risks. Currently, the resource utilization of oil refining byproducts has attracted attention. Vitamin E and sterols can be extracted for use in pharmaceutical raw material production, or converted into products such as biodiesel and surfactants, potentially achieving a balance between economic and environmental benefits. However, this field also faces significant technological bottlenecks: the composition of byproducts fluctuates greatly, leading to complex extraction processes, high production costs, and difficulty in effectively controlling product quality; furthermore, secondary pollution such as wastewater and exhaust gas may be generated during processing, hindering the progress of high-value and green utilization of oil refining byproducts. In summary, the current plywood industry urgently needs to address the problems of poor environmental performance, insufficient bonding reliability, and non-green and environmentally friendly production processes of traditional adhesives. At the same time, the high-value utilization of oil refining byproducts also faces technical obstacles. Therefore, developing a technical solution that can both meet the performance requirements of adhesives in plywood production and achieve the green and high-value utilization of oil refining byproducts has become a pressing technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies by proposing a non-grain oil-based formaldehyde-free adhesive, its preparation method, and its application. The plywood made with this adhesive releases no formaldehyde, and the plywood produced exhibits excellent bonding strength and water resistance. To achieve the above objectives, the present invention adopts the following technical solution: A non-grain oil-based formaldehyde-free adhesive comprises the following components by weight: 48-55 parts of oil refining byproducts, 25-32 parts of modifier, 0.8-1.8 parts of catalyst, 10-20 parts of crosslinking agent, 2 parts of butanone peroxide, and 3-8 parts of isocyanate.

[0006] Oil refining byproducts are industrial waste; using them as raw materials can avoid resource waste, reduce adhesive production costs, and decrease environmental pollution. This achieves resource recycling and improves the environmental friendliness of adhesives. Oil refining byproducts contain components such as long fatty acid chains, which can impart good bonding strength and durability to adhesives.

[0007] Furthermore, the modifier includes any one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxyethyl acrylate. The main components of oil refining byproducts are free fatty acids and glycerides. The modifier "links" oil molecules with modifier molecules to form more stable macromolecular chains, preventing "glue flow" in the adhesive before curing due to weak intermolecular forces. It also introduces active groups, enhancing the adhesion between the adhesive and wood, and improving bonding strength and water resistance. All modifiers are low-toxicity, low-volatility chemical raw materials, and no formaldehyde or benzene is released during the curing process, avoiding the formaldehyde exceeding standards problem of traditional urea-formaldehyde resins, and meeting the environmental protection requirements for indoor furniture, children's products, and other applications.

[0008] The catalyst is any one of triethylamine, sodium hydroxide, and tetrabutylammonium bromide. Catalysts such as triethylamine, sodium hydroxide, and tetrabutylammonium bromide effectively promote the transesterification reaction and other modification reactions of oil refining by-products, accelerate the reaction rate, reduce reaction time and energy consumption, shorten the production cycle, improve production efficiency, and at the same time ensure a more complete reaction, ensure stable adhesive quality, and enable the adhesive to achieve the expected performance.

[0009] The crosslinking agent is any one of ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, and 1,6-hexanediol dimethacrylate. This ensures that when the unsaturated double bonds of the modifier react with the crosslinking agent (such as ethylene glycol dimethacrylate) and the initiator (butanone peroxide), a three-dimensional network structure is formed between the molecular chains. This structure acts like a "molecular skeleton," locking the active groups in the adhesive and reducing the damage to the molecular chains caused by moisture and temperature. This improves the cohesive strength and adhesion of the adhesive, enhances the interlayer bonding strength of the plywood, and makes it less prone to delamination or separation in humid, dry, or drastically temperature-sensitive environments. It also improves the weather resistance and water resistance of the adhesive, enhancing its durability and meeting the requirements for long-term service of the adhesive in plywood.

[0010] The isocyanate is either polyhexamethylene diisocyanate or polydiphenylmethane diisocyanate. The isocyanate reacts with other hydrogen-containing groups in the adhesive to form strong chemical bonds, such as urethane bonds. This not only improves the adhesion strength between the adhesive and the surface of the bonded object, but also enhances the adhesive's water resistance and weather resistance, resulting in better overall performance of the plywood.

[0011] A method for preparing a non-grain oil-based formaldehyde-free adhesive includes the following steps: S1: Collect by-products of oil refining; collect waste oil mixtures generated during the refining process of vegetable oil industry to avoid resource waste, and use these by-products of oil refining to make adhesives, avoiding the problem of difficulty in extracting and utilizing by-products of oil refining by existing methods.

[0012] S2: Mix the oil refining by-products and the modifier at 90℃~95℃ for 45~60min to obtain a mixture; the mild initial temperature can make the oil refining by-products and the modifier initially uniformly mixed, which is beneficial to the subsequent reaction.

[0013] S3: Raise the reaction temperature to 105℃~110℃, add the catalyst to the mixture, and mechanically stir for 180 min to obtain an oil mixture; prolonged stirring after heating allows the catalyst to fully exert its effect, promotes reactions such as transesterification, improves adhesive performance, and ensures stable product quality.

[0014] S4: After cooling to room temperature, mix the oil mixture, methyl ethyl ketone peroxide, crosslinking agent and isocyanate and stir for 10-20 minutes to obtain an oil-based formaldehyde-free adhesive.

[0015] This invention uses byproducts from vegetable oil refining as raw materials, activates them through transesterification, and introduces crosslinking agents and isocyanates for modification, which significantly improves the bonding strength and water resistance of the adhesive.

[0016] Furthermore, the specific ratio of oil refining by-products to modifiers in the mixture is 60-68 parts of oil refining by-products and 32-40 parts of modifiers; the amount of catalyst added is 1-2% of the total mass of the mixture; in step S4, the specific ratio of the oil mixture, methyl ethyl ketone peroxide, crosslinking agent, and isocyanate is 80-90 parts of oil mixture, 10-20 parts of crosslinking agent, 2 parts of methyl ethyl ketone peroxide, and 3-8 parts of isocyanate. This ensures the adhesive's bonding performance, prevents formaldehyde release during the preparation process, and achieves high-value utilization of waste resources while reducing the raw material cost of the adhesive through a high proportion of oil refining by-products.

[0017] Furthermore, byproducts of oil refining originate from waste oil mixtures obtained during the industrial refining of vegetable oils such as waste cooking oil, palm oil, soybean oil, castor oil, and corn oil. These sources are widespread, enabling resource reuse, reducing costs, and protecting the environment.

[0018] Application of the above-mentioned non-grain oil-based formaldehyde-free adhesive in plywood.

[0019] Furthermore, the non-grain oil-based formaldehyde-free adhesive is coated onto the upper and lower surfaces of the poplar veneer, with a single-layer adhesive application rate of 150 g / cm². 2 By combining the cross grain of the core layer with the vertical grain of the outer layer, and hot-pressing at 150℃ and 2 MPa for 3 minutes, a non-grain oil-based formaldehyde-free plywood is obtained. This ensures that the adhesive forms a continuous and sufficiently thick glue layer between the poplar veneers, allowing for full contact and interpenetration between the adhesive and the poplar veneers. After curing, a stable bond is formed. Hot pressing accelerates the curing of the adhesive and improves the bonding strength. The combination of cross grain in the core layer and vertical grain in the outer layer utilizes the characteristics of the wood grain direction, making the mechanical properties of the plywood more balanced in all directions. This effectively improves the overall strength and stability, reducing problems such as deformation and cracking caused by uneven stress. Poplar veneer itself is non-toxic and environmentally friendly. The plywood produced by combining these two materials has the characteristics of no formaldehyde release and excellent environmental performance during use.

[0020] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention activates oil refining byproducts through a simple transesterification reaction to prepare a formaldehyde-free adhesive suitable for plywood. It features renewable raw materials, a simple and efficient preparation process, and environmental friendliness. Plywood prepared using this method releases no formaldehyde during use and exhibits excellent bonding strength and water resistance. This invention not only provides a new approach for the high-value utilization of oil byproducts, but the prepared adhesive also meets the performance requirements for use in the production of engineered wood products. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the steps of preparing the non-grain oil-based formaldehyde-free adhesive of the present invention. Detailed Implementation

[0022] To provide a further understanding of the purpose, structure, features, and functions of the present invention, detailed descriptions are provided below with reference to specific embodiments.

[0023] like Figure 1 A method for preparing a non-grain oil-based formaldehyde-free adhesive includes the following steps: S1: Collect by-products from oil refining; S2: Mix the oil refining byproducts with the modifier at 90℃~95℃ for 45~60min to obtain a mixture; S3: Increase the reaction temperature to 105℃~110℃, add the catalyst to the mixture, and mechanically stir for 180 min to obtain the oil mixture; S4: After cooling to room temperature, mix the oil mixture, methyl ethyl ketone peroxide, crosslinking agent and isocyanate and stir for 10-20 minutes to obtain an oil-based formaldehyde-free adhesive.

[0024] Raw materials: Byproducts of oil refining are derived from waste oil mixtures obtained from the refining of vegetable oils such as waste cooking oil, palm oil, soybean oil, castor oil, and corn oil; these byproducts are collected. Hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, triethylamine, sodium hydroxide, tetrabutylammonium bromide, ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, methyl ethyl ketone peroxide, polyhexamethylene diisocyanate, and polydiphenylmethane diisocyanate were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0025] Example 1

[0026] The preparation process of the non-grain oil-based formaldehyde-free adhesive is as follows: 52 g of oil refining byproducts and 28 g of hydroxyethyl methacrylate are mixed and stirred at 90℃ for 45 min, then heated to 105℃, and 1% triethylamine is added and stirred for 180 min. After cooling to room temperature, 20 g of 1,4-butanediol dimethacrylate, 2 g of butanone peroxide, and 3 g of polydiphenylmethane diisocyanate are added and stirred for 10 min.

[0027] The plywood preparation process is as follows: the non-grain oil-based formaldehyde-free adhesive is coated onto the upper and lower surfaces of poplar veneer, with a single-layer adhesive application rate of 150 g / cm³. 2 By combining the horizontal stripes of the core layer and the vertical stripes of the outer layer, hot pressing is performed at 150℃ and 2 MPa pressure for 3 minutes to obtain a non-grain oil-based formaldehyde-free plywood.

[0028] Example 2

[0029] Replace 1% triethylamine in Example 1 with 2% triethylamine, and follow the same steps as in Example 1.

[0030] Example 3

[0031] Replace 1% triethylamine in Example 1 with 1% sodium hydroxide, and follow the same steps as in Example 1.

[0032] Example 4

[0033] Replace 1% triethylamine in Example 1 with 1% tetrabutylammonium bromide, and follow the same steps as in Example 1.

[0034] Example 5

[0035] Replace 52 g of oil refining byproducts and 28 g of hydroxyethyl methacrylate in Example 1 with 48 g of oil refining byproducts and 32 g of hydroxypropyl methacrylate, and follow the same steps as in Example 1.

[0036] Example 6

[0037] Replace 52 g of oil refining byproducts and 28 g of hydroxyethyl methacrylate in Example 1 with 55 g of oil refining byproducts and 25 g of hydroxyethyl acrylate, and follow the same steps as in Example 1.

[0038] Example 7

[0039] Replace 20 g of 1,4-butanediol dimethacrylate in Example 1 with 20 g of ethylene glycol dimethacrylate, and follow the same steps as in Example 1.

[0040] Example 8

[0041] Replace 20 g of 1,4-butanediol dimethacrylate in Example 1 with 20 g of 1,6-hexanediol dimethacrylate, and follow the same steps as in Example 1.

[0042] Example 9

[0043] Replace 3 g of polydiphenylmethane diisocyanate in Example 1 with 3 g of polyhexamethylene diisocyanate, and follow the same steps as in Example 1.

[0044] Example 10

[0045] Replace 3 g of polydiphenylmethane diisocyanate in Example 1 with 5 g of polydiphenylmethane diisocyanate, and follow the same steps as in Example 1.

[0046] Example 11

[0047] Replace 3 g of polydiphenylmethane diisocyanate in Example 1 with 8 g of polydiphenylmethane diisocyanate, and follow the same steps as in Example 1.

[0048] Example 12

[0049] Replace 3 g of polydiphenylmethane diisocyanate in Example 1 with 5 g of polyhexamethylene diisocyanate, and follow the same steps as in Example 1.

[0050] Example 13

[0051] Replace 3 g of polydiphenylmethane diisocyanate in Example 1 with 8 g of polyhexamethylene diisocyanate, and follow the same steps as in Example 1.

[0052] Adhesion strength test: According to the national standard testing specification GB / T 17657-2013, the bonding strength of plywood was tested. Specifically, the prepared plywood was cut into specimens with a length of 100 ± 1 mm and a width of 25 ± 1 mm. The specimens were soaked in constant temperature water at 63℃ for 3 hours. After being removed, the surface water stains were wiped dry. The specimens were then grooved and their bonding strength was tested on a computer-controlled electronic universal testing machine. Each group of samples was tested 12 times.

[0053] The bonding strength of non-grain oil-based formaldehyde-free plywood was obtained by summarizing the sample test results: The mechanical properties of the prepared formaldehyde-free plywood are shown in Table 1. The bond strength of three-layer plywood from 13 different examples was tested. The dry bond strength ranged from 0.91 to 1.62 MPa, with the highest value in Example 11 (1.62 ± 0.51 MPa) and the lowest in Example 9 (0.91 ± 0.11 MPa). The wet bond strength was measured after immersion in water at 63°C for 180 min, and the values ​​ranged from 0.54 to 1.16 MPa. Again, Example 11 had the highest value (1.16 ± 0.16 MPa), and Example 9 had the lowest value (0.54 ± 0.08 MPa). In summary, the plywood prepared using the adhesive exhibits excellent bond strength, maintains high bond strength even after immersion in constant-temperature water, has good water resistance, and reduces delamination or separation. This invention not only provides a new way to utilize oil by-products for high value, but also the adhesive prepared meets the performance requirements for use in the production of engineered wood products.

[0054]

[0055] The present invention has been described in the above-described embodiments; however, these embodiments are merely examples for implementing the present invention. It must be noted that the disclosed embodiments do not limit the scope of the present invention. Conversely, any modifications and refinements made without departing from the spirit and scope of the present invention are within the scope of patent protection of the present invention.

Claims

1. A non-grain oil-based formaldehyde-free adhesive, characterized in that: It includes the following components by weight: 48-55 parts of oil refining byproducts, 25-32 parts of modifier, 0.8-1.8 parts of catalyst, 10-20 parts of crosslinking agent, 2 parts of butanone peroxide and 3-8 parts of isocyanate.

2. The non-grain oil-based formaldehyde-free adhesive as described in claim 1, characterized in that: The modifier includes any one of hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxyethyl acrylate; the catalyst is any one of triethylamine, sodium hydroxide, and tetrabutylammonium bromide; the crosslinking agent is any one of ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, and 1,6-hexanediol dimethacrylate; and the isocyanate is any one of polyhexamethylene diisocyanate and polydiphenylmethane diisocyanate.

3. A method for preparing a non-grain oil-based formaldehyde-free adhesive as described in claim 1 or 2, characterized in that: Includes the following steps: S1: Collect by-products from oil refining; S2: Mix the oil refining byproducts with the modifier at 90℃~95℃ for 45~60min to obtain a mixture; S3: Increase the reaction temperature to 105℃~110℃, add the catalyst to the mixture, and mechanically stir for 180 min to obtain the oil mixture; S4: After cooling to room temperature, mix the oil mixture, methyl ethyl ketone peroxide, crosslinking agent and isocyanate and stir for 10-20 minutes to obtain an oil-based formaldehyde-free adhesive.

4. The preparation method of the non-grain oil-based formaldehyde-free adhesive as described in claim 3, characterized in that: The specific ratio of oil refining by-products to modifiers in the mixture is: 60-68 parts of oil refining by-products and 32-40 parts of modifiers; the amount of catalyst added is 1-2% of the total mass of the mixture; in step S4, the specific ratio of oil mixture, methyl ethyl ketone peroxide, crosslinking agent and isocyanate is: 80-90 parts of oil mixture, 10-20 parts of crosslinking agent, 2 parts of methyl ethyl ketone peroxide and 3-8 parts of isocyanate.

5. The method for preparing the non-grain oil-based formaldehyde-free adhesive as described in claim 3, characterized in that: Oil refining byproducts are waste oil mixtures obtained during the refining process of vegetable oil industry.

6. The application of a non-grain oil-based formaldehyde-free adhesive as described in claim 1 or 2, or a non-grain oil-based formaldehyde-free adhesive prepared by any of the preparation methods of claims 3-5, in plywood.

7. The application of the non-grain oil-based formaldehyde-free adhesive as described in claim 6 in plywood, characterized in that: The non-grain oil-based formaldehyde-free adhesive was applied to the upper and lower surfaces of poplar veneer, with a single-layer adhesive application rate of 150 g / cm². 2 By combining the horizontal stripes of the core layer and the vertical stripes of the outer layer, hot pressing is performed at 150℃ and 2 MPa pressure for 3 minutes to obtain a non-grain oil-based formaldehyde-free plywood.

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