Preparation method and application of high-performance high-flexibility formaldehyde-free impregnated film paper

Abstract

The application relates to a preparation method of high-performance high-flexibility formaldehyde-free impregnated film paper and application thereof, and belongs to the technical field of impregnated film paper. The application aims to solve the problems that the existing impregnated film paper cannot simultaneously have high strength, high toughness, crack resistance, scratch resistance, wear resistance and formaldehyde-free release, and the low adhesive transparency influences the paper texture. Preparation: 1, adjusting the pH of polyamide epoxy chloropropane resin; 2, preparing polyvinyl alcohol / melamine adhesive; 3, impregnating the decorative base paper in the polyamide epoxy chloropropane resin after the pH is adjusted, then drying to obtain primary impregnated paper, and then impregnating the primary impregnated paper in the polyvinyl alcohol / melamine adhesive at room temperature, and then drying to obtain high-performance high-flexibility formaldehyde-free impregnated film paper. Application: the high-performance high-flexibility formaldehyde-free impregnated film paper is used as a veneer material of artificial board.

Description

Technical Field

[0001] This invention belongs to the field of impregnated paper technology. Background Technology

[0002] Impregnated paper is widely used as a veneer material for engineered wood products (fiberboard, particleboard, blockboard, etc.) due to its aesthetic appeal and its decorative and protective properties. Among all engineered wood veneer materials, impregnated paper is simple to produce, inexpensive, and highly efficient, resulting in the largest market share, approximately 60%.

[0003] Because urea-formaldehyde resin and melamine-formaldehyde resin are relatively inexpensive and of good quality, and are aqueous solutions of low-molecular-weight condensation resins, they can easily penetrate into decorative paper, giving the surface of engineered wood panels added value. Furthermore, the resulting impregnated paper exhibits good wear and scratch resistance. Therefore, urea-formaldehyde resin and melamine-formaldehyde impregnated paper are currently the dominant types on the market. However, melamine-impregnated paper releases free formaldehyde during production and use, posing a significant health hazard. In addition, melamine-impregnated paper is brittle and unsuitable for use on irregularly shaped curved surfaces. Moreover, when laminated with engineered wood panels, changes in temperature and humidity can lead to cracking. With the improvement of living standards and the implementation of relevant national policies, the formaldehyde-free and toughened impregnated paper is of great significance.

[0004] Currently, the main approach to achieving formaldehyde-free decorative paper is through the use of formaldehyde-free impregnating adhesives. These formaldehyde-free adhesives primarily include inorganic adhesives, soybean protein adhesives, waterborne polyurethane resin adhesives, and polyacrylic acid resin adhesives. However, inorganic adhesives used in decorative paper impregnation suffer from poor paper flexibility and low adhesive transparency, affecting paper texture. Soybean protein adhesives result in weak adhesion and low bonding strength. While waterborne polyurethane resin adhesives offer strong bonding, their scratch resistance needs improvement. Modified polyacrylic acid resin adhesives, while improving scratch resistance, suffer from lower physical and mechanical properties, low abrasion resistance, and lower pattern clarity. Therefore, existing formaldehyde-free impregnated decorative paper is still insufficient to replace melamine-impregnated paper. Summary of the Invention

[0005] This invention aims to solve the problems that existing impregnated paper cannot simultaneously possess high strength, high toughness, crack resistance, scratch resistance, abrasion resistance, and formaldehyde-free properties, and that the low transparency of the adhesive affects the paper texture. Therefore, it provides a method for preparing high-performance, highly flexible, formaldehyde-free impregnated paper and its application.

[0006] A method for preparing a high-performance, highly flexible, formaldehyde-free impregnated paper comprises the following steps:

[0007] 1. Adjust the pH value of the polyamide epichlorohydrin resin to 7-11 to obtain the pH-adjusted polyamide epichlorohydrin resin;

[0008] 2. Dissolve polyvinyl alcohol in distilled water, then add melamine, and react for 1 to 7 hours at a temperature of 90℃ to 100℃ and a stirring speed of 300 rpm to 600 rpm. Finally, cool to room temperature to obtain polyvinyl alcohol / melamine adhesive.

[0009] 3. At room temperature, the decorative base paper is first impregnated in a pH-adjusted polyamide epichlorohydrin resin and then dried to obtain a first-impregnated paper. At room temperature, the first-impregnated paper is then impregnated in a polyvinyl alcohol / melamine adhesive and then dried to obtain a high-performance, highly flexible, formaldehyde-free impregnated film paper.

[0010] An application of a high-performance, highly flexible, formaldehyde-free impregnated paper, used as a finishing material for engineered wood panels.

[0011] The beneficial effects of this invention are:

[0012] (1) The raw material of this impregnating adhesive is water-based, making it green and environmentally friendly; (2) The preparation process of this impregnating resin is simple, suitable for large-scale production, and the preparation process is pollution-free; (3) The adhesive releases no formaldehyde and is highly transparent; (4) The formaldehyde-free flexible impregnating film paper is formaldehyde-free and highly flexible; (5) After water activation, the formaldehyde-free flexible impregnating film paper exhibits excellent surface bonding strength, wear resistance, scratch resistance, and crack resistance in the finished artificial board; (6) The formaldehyde-free flexible impregnating film paper is prepared using a layer-by-layer self-assembly process, which is simple and easy to control, and is expected to replace melamine impregnating film paper. Attached Figure Description

[0013] Figure 1 The images show the flexibility of the high-performance, high-flexibility formaldehyde-free impregnated paper, decorative base paper, and melamine impregnated paper prepared in Example 4. a is the decorative base paper, b is the melamine impregnated paper, and c is the high-performance, high-flexibility formaldehyde-free impregnated paper.

[0014] Figure 2 The image shows an infrared spectrum; a is the decorative base paper, b is the primary impregnated paper prepared in step three of Example 4, and c is the high-performance, highly flexible, formaldehyde-free impregnated film paper prepared in step three of Example 4.

[0015] Figure 3 A photograph of the polyvinyl alcohol / melamine adhesive prepared in Example 2;

[0016] Figure 4 The images show actual pictures of the decorative base paper and the impregnated film paper. a is the decorative base paper, and b is the high-performance, highly flexible, formaldehyde-free impregnated film paper prepared in Example 2. Detailed Implementation

[0017] Specific Implementation Method 1: This implementation method is a method for preparing high-performance, highly flexible, formaldehyde-free impregnated adhesive film paper, which is carried out according to the following steps:

[0018] 1. Adjust the pH value of the polyamide epichlorohydrin resin to 7-11 to obtain the pH-adjusted polyamide epichlorohydrin resin;

[0019] 2. Dissolve polyvinyl alcohol in distilled water, then add melamine, and react for 1 to 7 hours at a temperature of 90℃ to 100℃ and a stirring speed of 300 rpm to 600 rpm. Finally, cool to room temperature to obtain polyvinyl alcohol / melamine adhesive.

[0020] 3. At room temperature, the decorative base paper is first impregnated in a pH-adjusted polyamide epichlorohydrin resin and then dried to obtain a first-impregnated paper. At room temperature, the first-impregnated paper is then impregnated in a polyvinyl alcohol / melamine adhesive and then dried to obtain a high-performance, highly flexible, formaldehyde-free impregnated film paper.

[0021] The polyvinyl alcohol / melamine adhesive prepared in step two of this specific embodiment is a flexible long-chain adhesive with high flexibility and good transparency.

[0022] In this specific embodiment, step three involves two-step impregnation with polyamide epichlorohydrin resin (PAE resin, wet strength agent) and polyvinyl alcohol / melamine adhesive to achieve a layer-by-layer self-assembly strategy.

[0023] The superior performance of the impregnated paper in this specific embodiment depends on two factors: the effect of pH on the activity of the polyamide epichlorohydrin resin and the effect of controlling the solid content of the polyvinyl alcohol / melamine adhesive. By utilizing the impregnation of these two resins for layer-by-layer self-assembly and synergistic control, the performance of the prepared impregnated paper is optimized. Finally, after water activation, it is applied to the surface of engineered wood panels, ensuring that the surface bonding performance, surface abrasion resistance, surface scratch resistance, and surface crack resistance all meet national standards.

[0024] Principle: Traditionally, PAE / PVA / MA blends are highly reactive, have high viscosity, and are prone to gelation. To achieve synergy between the wet strength of PAE resin and the toughening properties of PVA / MA, an innovative layer-by-layer self-assembly strategy is employed. The impregnated paper uses decorative paper as the base paper. The first layer is impregnated with PAE resin, which undergoes a self-crosslinking reaction within the base paper, forming a first-layer network structure through ester bonds. After drying, some active molecules are sealed, resulting in impregnated paper with improved water resistance. The second layer is loaded with PVA / MA adhesive, which forms a second-layer network structure through hydrogen bond supramolecular crosslinking. After drying, a formaldehyde-free flexible impregnated paper is obtained. Polyamide epichlorohydrin resin and polyvinyl alcohol / melamine adhesive synergistically combine within the paper network structure to form covalent and hydrogen bonds. Through layer-by-layer self-assembly on the base paper, a chemically and physically combined double-crosslinked network is formed, giving the impregnated paper formaldehyde-free properties, flexibility, and bonding strength. After coating the surface of formaldehyde-free flexible impregnated paper with tap water (water activation), the active groups (hydrogen bonds) of the formaldehyde-free flexible impregnated paper are highly activated. This paper is then hot-pressed with a particleboard under specific temperature and pressure on one side for a period of time. During hot pressing, hydrogen bonds, chemical bonds, and mechanical interlocking forces are generated, forming excellent adhesive strength. This yields a formaldehyde-free flexible impregnated paper-faced particleboard.

[0025] The beneficial effects of this embodiment are:

[0026] (1) The raw material of this impregnating adhesive is water-based, making it green and environmentally friendly; (2) The preparation process of this impregnating resin is simple, suitable for large-scale production, and the preparation process is pollution-free; (3) The adhesive releases no formaldehyde and is highly transparent; (4) The formaldehyde-free flexible impregnating film paper is formaldehyde-free and highly flexible; (5) After water activation, the formaldehyde-free flexible impregnating film paper exhibits excellent surface bonding strength, wear resistance, scratch resistance, and crack resistance in the finished artificial board; (6) The formaldehyde-free flexible impregnating film paper is prepared using a layer-by-layer self-assembly process, which is simple and easy to control, and is expected to replace melamine impregnating film paper.

[0027] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that, in step one, a NaOH solution with a concentration of 1 mol / L to 3 mol / L is added dropwise to the polyamide epichlorohydrin resin at a rotation speed of 500 rpm to 1000 rpm until the pH value reaches 7 to 11. Everything else is the same as in Specific Implementation Method One.

[0028] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the solid content of the polyamide epichlorohydrin resin mentioned in step one is 5% to 20%. Everything else is the same as in Specific Implementation Method One or Two.

[0029] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: the mass percentage of polyvinyl alcohol in the polyvinyl alcohol / melamine adhesive described in step two is 5% to 20%; the mass percentage of melamine in the polyvinyl alcohol / melamine adhesive described in step two is 0.1% to 2%. Everything else is the same as in Specific Implementation Methods One to Three.

[0030] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that, in step three, the decorative base paper is first immersed in a pH-adjusted polyamide epichlorohydrin resin at room temperature for 2 to 10 minutes. Everything else is the same as in Specific Implementation Methods One to Four.

[0031] Specific embodiment six differs from specific embodiments one to five in that: in step three, the impregnated paper is further impregnated in polyvinyl alcohol / melamine adhesive for 2 to 5 minutes at room temperature. Everything else is the same as specific embodiments one to five.

[0032] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the drying process in step three is specifically carried out at a temperature of 50℃ to 90℃ for 10 to 15 minutes. Everything else is the same as in Specific Implementation Methods One to Six.

[0033] Specific Implementation Method 8: This implementation method describes the application of a high-performance, highly flexible, formaldehyde-free impregnated paper, which is used as a finishing material for engineered wood panels.

[0034] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that, when used as a surface material for engineered wood panels, it is carried out according to the following steps:

[0035] High-performance, highly flexible, formaldehyde-free impregnated paper is water-activated to obtain activated impregnated paper. The activated impregnated paper is then applied to the surface of the engineered wood panel, and finally hot-pressed to obtain the decorative engineered wood panel. Other aspects are the same as in specific embodiment eight.

[0036] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Eight or Nine in that the water activation treatment is specifically carried out according to the following steps: at room temperature, with a coating amount of 0.1 g / cm³... 2 ~1g / cm 2 Water is applied to the surface of the high-performance, highly flexible, formaldehyde-free impregnated adhesive film to be pasted, and left to stand for 1 to 3 minutes. The hot pressing is specifically carried out at a hot pressing temperature of 170°C to 230°C and a hot pressing pressure of 1 MPa to 3 MPa for 10 seconds to 3 minutes. Other aspects are the same as in specific embodiments eight or nine.

[0037] The beneficial effects of the present invention are verified using the following embodiments:

[0038] Example 1:

[0039] A method for preparing a high-performance, highly flexible, formaldehyde-free impregnated paper comprises the following steps:

[0040] 1. Under the condition of 800 rpm, a 2 mol / L NaOH solution was added dropwise to the polyamide epichlorohydrin resin until the pH value was 7, thus obtaining the pH-adjusted polyamide epichlorohydrin resin.

[0041] The solid content of the polyamide epichlorohydrin resin is 12.5%.

[0042] 2. Dissolve polyvinyl alcohol in distilled water, then add melamine, and react for 6 hours at a temperature of 95℃ and a stirring speed of 500 rpm. Finally, cool to room temperature to obtain polyvinyl alcohol / melamine adhesive.

[0043] The polyvinyl alcohol / melamine adhesive contains 7% polyvinyl alcohol by mass; the polyvinyl alcohol / melamine adhesive contains 0.75% melamine by mass.

[0044] 3. At room temperature, the decorative base paper is first impregnated in the pH-adjusted polyamide epichlorohydrin resin for 5 minutes, and then dried to obtain a first-impregnated paper. At room temperature, the first-impregnated paper is then impregnated in polyvinyl alcohol / melamine adhesive for 2 minutes, and then dried to obtain a high-performance, high-flexibility, formaldehyde-free impregnated film paper.

[0045] The decorative base paper is made of fibers, manufactured by Qifeng New Materials Co., Ltd., model number 9027-83g, with a thickness of 0.09mm and an area of ​​30×30cm. 2 The drying process specifically involves drying at 60°C for 12 minutes; the thickness of the high-performance, highly flexible, formaldehyde-free impregnated paper is 0.25 mm.

[0046] IV. The high-performance, high-flexibility, formaldehyde-free impregnated paper is water-activated to obtain activated impregnated paper. The activated impregnated paper is then applied to the surface of the engineered wood panel and finally hot-pressed to obtain the decorative engineered wood panel.

[0047] The aforementioned engineered wood product is fiberboard; the water activation treatment is specifically carried out according to the following steps: at room temperature, with a coating amount of 0.5 g / cm³. 2 Water is applied to the surface of the high-performance, highly flexible, formaldehyde-free impregnated adhesive film to be pasted, and left to stand for 1 to 3 minutes; the hot pressing is specifically carried out at a hot pressing temperature of 200°C and a hot pressing pressure of 2 MPa for 1 minute.

[0048] Example 2:

[0049] A method for preparing a high-performance, highly flexible, formaldehyde-free impregnated paper comprises the following steps:

[0050] 1. Under the condition of 800 rpm, a 2 mol / L NaOH solution was added dropwise to the polyamide epichlorohydrin resin until the pH value was 9, thus obtaining the pH-adjusted polyamide epichlorohydrin resin.

[0051] The solid content of the polyamide epichlorohydrin resin is 12.5%.

[0052] 2. Dissolve polyvinyl alcohol in distilled water, then add melamine, and react for 6 hours at a temperature of 95℃ and a stirring speed of 500 rpm. Finally, cool to room temperature to obtain polyvinyl alcohol / melamine adhesive.

[0053] The polyvinyl alcohol / melamine adhesive contains 8% polyvinyl alcohol by mass; the polyvinyl alcohol / melamine adhesive contains 0.75% melamine by mass.

[0054] 3. At room temperature, the decorative base paper is first impregnated in the pH-adjusted polyamide epichlorohydrin resin for 5 minutes, and then dried to obtain a first-impregnated paper. At room temperature, the first-impregnated paper is then impregnated in polyvinyl alcohol / melamine adhesive for 2 minutes, and then dried to obtain a high-performance, high-flexibility, formaldehyde-free impregnated film paper.

[0055] The decorative base paper is made of fibers, manufactured by Qifeng New Materials Co., Ltd., model number 9027-83g, with a thickness of 0.09mm and an area of ​​30×30cm. 2 The drying process specifically involves drying at 60°C for 12 minutes; the thickness of the high-performance, highly flexible, formaldehyde-free impregnated paper is 0.25 mm.

[0056] IV. The high-performance, high-flexibility, formaldehyde-free impregnated paper is water-activated to obtain activated impregnated paper. The activated impregnated paper is then applied to the surface of the engineered wood panel and finally hot-pressed to obtain the decorative engineered wood panel.

[0057] The aforementioned engineered wood product is fiberboard; the water activation treatment is specifically carried out according to the following steps: at room temperature, with a coating amount of 0.5 g / cm³. 2 Water is applied to the surface of the high-performance, highly flexible, formaldehyde-free impregnated adhesive film to be pasted, and left to stand for 1 to 3 minutes; the hot pressing is specifically carried out at a hot pressing temperature of 200°C and a hot pressing pressure of 2 MPa for 1 minute.

[0058] Example 3:

[0059] A method for preparing a high-performance, highly flexible, formaldehyde-free impregnated paper comprises the following steps:

[0060] 1. Under the condition of 800 rpm, a 2 mol / L NaOH solution was added dropwise to the polyamide epichlorohydrin resin until the pH value was 11, thus obtaining the pH-adjusted polyamide epichlorohydrin resin.

[0061] The solid content of the polyamide epichlorohydrin resin is 12.5%.

[0062] 2. Dissolve polyvinyl alcohol in distilled water, then add melamine, and react for 6 hours at a temperature of 95℃ and a stirring speed of 500 rpm. Finally, cool to room temperature to obtain polyvinyl alcohol / melamine adhesive.

[0063] The polyvinyl alcohol / melamine adhesive contains 9% polyvinyl alcohol by mass; the polyvinyl alcohol / melamine adhesive contains 0.75% melamine by mass.

[0064] 3. At room temperature, the decorative base paper is first impregnated in the pH-adjusted polyamide epichlorohydrin resin for 5 minutes, and then dried to obtain a first-impregnated paper. At room temperature, the first-impregnated paper is then impregnated in polyvinyl alcohol / melamine adhesive for 2 minutes, and then dried to obtain a high-performance, high-flexibility, formaldehyde-free impregnated film paper.

[0065] The decorative base paper is made of fibers, manufactured by Qifeng New Materials Co., Ltd., model number 9027-83g, with a thickness of 0.09mm and an area of ​​30×30cm. 2 The drying process specifically involves drying at 60°C for 12 minutes; the thickness of the high-performance, highly flexible, formaldehyde-free impregnated paper is 0.25 mm.

[0066] IV. The high-performance, high-flexibility, formaldehyde-free impregnated paper is water-activated to obtain activated impregnated paper. The activated impregnated paper is then applied to the surface of the engineered wood panel and finally hot-pressed to obtain the decorative engineered wood panel.

[0067] The aforementioned engineered wood product is fiberboard; the water activation treatment is specifically carried out according to the following steps: at room temperature, with a coating amount of 0.5 g / cm³. 2 Water is applied to the surface of the high-performance, highly flexible, formaldehyde-free impregnated adhesive film to be pasted, and left to stand for 1 to 3 minutes; the hot pressing is specifically carried out at a hot pressing temperature of 200°C and a hot pressing pressure of 2 MPa for 1 minute.

[0068] Example 4:

[0069] A method for preparing a high-performance, highly flexible, formaldehyde-free impregnated paper comprises the following steps:

[0070] 1. Under the condition of 800 rpm, a 2 mol / L NaOH solution was added dropwise to the polyamide epichlorohydrin resin until the pH value was 7, thus obtaining the pH-adjusted polyamide epichlorohydrin resin.

[0071] The solid content of the polyamide epichlorohydrin resin is 12.5%.

[0072] 2. Dissolve polyvinyl alcohol in distilled water, then add melamine, and react for 6 hours at a temperature of 95℃ and a stirring speed of 500 rpm. Finally, cool to room temperature to obtain polyvinyl alcohol / melamine adhesive.

[0073] The polyvinyl alcohol / melamine adhesive contains 8% polyvinyl alcohol by mass; the polyvinyl alcohol / melamine adhesive contains 0.75% melamine by mass.

[0074] 3. At room temperature, the decorative base paper is first impregnated in the pH-adjusted polyamide epichlorohydrin resin for 5 minutes, and then dried to obtain a first-impregnated paper. At room temperature, the first-impregnated paper is then impregnated in polyvinyl alcohol / melamine adhesive for 2 minutes, and then dried to obtain a high-performance, high-flexibility, formaldehyde-free impregnated film paper.

[0075] The decorative base paper is made of fibers, manufactured by Qifeng New Materials Co., Ltd., model number 9027-83g, with a thickness of 0.09mm and an area of ​​30×30cm. 2 The drying process specifically involves drying at 60°C for 12 minutes; the thickness of the high-performance, highly flexible, formaldehyde-free impregnated paper is 0.25 mm.

[0076] IV. The high-performance, high-flexibility, formaldehyde-free impregnated paper is water-activated to obtain activated impregnated paper. The activated impregnated paper is then applied to the surface of the engineered wood panel and finally hot-pressed to obtain the decorative engineered wood panel.

[0077] The aforementioned engineered wood product is fiberboard; the water activation treatment is specifically carried out according to the following steps: at room temperature, with a coating amount of 0.5 g / cm³. 2 Water is applied to the surface of the high-performance, highly flexible, formaldehyde-free impregnated adhesive film to be pasted, and left to stand for 1 to 3 minutes; the hot pressing is specifically carried out at a hot pressing temperature of 200°C and a hot pressing pressure of 2 MPa for 1 minute.

[0078] Example 5:

[0079] A method for preparing a high-performance, highly flexible, formaldehyde-free impregnated paper comprises the following steps:

[0080] 1. Under the condition of 800 rpm, a 2 mol / L NaOH solution was added dropwise to the polyamide epichlorohydrin resin until the pH value was 9, thus obtaining the pH-adjusted polyamide epichlorohydrin resin.

[0081] The solid content of the polyamide epichlorohydrin resin is 12.5%.

[0082] 2. Dissolve polyvinyl alcohol in distilled water, then add melamine, and react for 6 hours at a temperature of 95℃ and a stirring speed of 500 rpm. Finally, cool to room temperature to obtain polyvinyl alcohol / melamine adhesive.

[0083] The polyvinyl alcohol / melamine adhesive contains 9% polyvinyl alcohol by mass; the polyvinyl alcohol / melamine adhesive contains 0.75% melamine by mass.

[0084] 3. At room temperature, the decorative base paper is first impregnated in the pH-adjusted polyamide epichlorohydrin resin for 5 minutes, and then dried to obtain a first-impregnated paper. At room temperature, the first-impregnated paper is then impregnated in polyvinyl alcohol / melamine adhesive for 2 minutes, and then dried to obtain a high-performance, high-flexibility, formaldehyde-free impregnated film paper.

[0085] The decorative base paper is made of fibers, manufactured by Qifeng New Materials Co., Ltd., model number 9027-83g, with a thickness of 0.09mm and an area of ​​30×30cm. 2 The drying process specifically involves drying at 60°C for 12 minutes; the thickness of the high-performance, highly flexible, formaldehyde-free impregnated paper is 0.25 mm.

[0086] IV. The high-performance, high-flexibility, formaldehyde-free impregnated paper is water-activated to obtain activated impregnated paper. The activated impregnated paper is then applied to the surface of the engineered wood panel and finally hot-pressed to obtain the decorative engineered wood panel.

[0087] The aforementioned engineered wood product is fiberboard; the water activation treatment is specifically carried out according to the following steps: at room temperature, with a coating amount of 0.5 g / cm³. 2 Water is applied to the surface of the high-performance, highly flexible, formaldehyde-free impregnated adhesive film to be pasted, and left to stand for 1 to 3 minutes; the hot pressing is specifically carried out at a hot pressing temperature of 200°C and a hot pressing pressure of 2 MPa for 1 minute.

[0088] Comparative Experiment 1:

[0089] A method for preparing a high-performance, highly flexible, formaldehyde-free impregnated paper comprises the following steps:

[0090] 1. Under the condition of 800 rpm, a 2 mol / L NaOH solution was added dropwise to the polyamide epichlorohydrin resin until the pH value was 13, thus obtaining the pH-adjusted polyamide epichlorohydrin resin.

[0091] The solid content of the polyamide epichlorohydrin resin is 12.5%.

[0092] 2. Dissolve polyvinyl alcohol in distilled water, then add melamine, and react for 6 hours at a temperature of 95℃ and a stirring speed of 500 rpm. Finally, cool to room temperature to obtain polyvinyl alcohol / melamine adhesive.

[0093] The polyvinyl alcohol / melamine adhesive contains 7% polyvinyl alcohol by mass; the polyvinyl alcohol / melamine adhesive contains 0.75% melamine by mass.

[0094] 3. At room temperature, the decorative base paper is first impregnated in the pH-adjusted polyamide epichlorohydrin resin for 5 minutes, and then dried to obtain a first-impregnated paper. At room temperature, the first-impregnated paper is then impregnated in polyvinyl alcohol / melamine adhesive for 2 minutes, and then dried to obtain a high-performance, high-flexibility, formaldehyde-free impregnated film paper.

[0095] The decorative base paper is made of fibers, manufactured by Qifeng New Materials Co., Ltd., model number 9027-83g, with a thickness of 0.09mm and an area of ​​30×30cm. 2 The drying process specifically involves drying at 60°C for 12 minutes; the thickness of the high-performance, highly flexible, formaldehyde-free impregnated paper is 0.25 mm.

[0096] IV. The high-performance, high-flexibility, formaldehyde-free impregnated paper is water-activated to obtain activated impregnated paper. The activated impregnated paper is then applied to the surface of the engineered wood panel and finally hot-pressed to obtain the decorative engineered wood panel.

[0097] The aforementioned engineered wood product is fiberboard; the water activation treatment is specifically carried out according to the following steps: at room temperature, with a coating amount of 0.5 g / cm³. 2 Water is applied to the surface of the high-performance, highly flexible, formaldehyde-free impregnated adhesive film to be pasted, and left to stand for 1 to 3 minutes; the hot pressing is specifically carried out at a hot pressing temperature of 200°C and a hot pressing pressure of 2 MPa for 1 minute.

[0098] Comparative Experiment 2: This comparative experiment differs from Example 2 in that the water activation treatment in step four of Example 2 is omitted. Everything else is the same as Example 2.

[0099] To verify the performance characteristics of high-performance, highly flexible, formaldehyde-free impregnated paper, decorative base paper and melamine impregnated paper were used as comparative experiments (the decorative base paper is composed of fibers, manufactured by Qifeng New Materials Co., Ltd., model 9027-83g, thickness 0.09mm, and area 30×30cm). 2 The melamine-impregnated paper mentioned is manufactured by Shandong Kaide Wood Industry Co., Ltd., and is warm white in color, 0.2mm thick, and 30×30cm in size. 2 And perform the following tests:

[0100] Tensile strength was tested according to the national standard GB / T453-2002 "Determination of tensile strength of paper and paperboard" and the elongation at break was calculated. Formaldehyde emission was tested according to the national standard GB / T 28995-2022 "Artificial boards and decorative paper".

[0101] The surface physical and mechanical properties of the decorative wood-based panels were tested in accordance with the national standard GB / T 17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels". The main tests included the surface bonding strength, surface abrasion resistance, surface scratch resistance and surface cracking resistance of the decorative wood-based panels.

[0102] 1. Surface adhesive strength test

[0103] Surface bond strength was tested using a universal testing machine (AGS-X, Shimadzu) according to Chinese national standard GB / T 17657-2022. The sample dimensions were 50mm × 50mm × 2mm (thickness). A 1000mm diameter section was cut from the surface. 2 A circular groove was used for the test area, and the clip was glued to the circular surface of the specimen using hot melt adhesive. A steel pad on the back of the specimen was also glued with hot melt adhesive to enhance its strength. The tensile speed was 1 mm / min. Each sample was tested six times, and the average value was taken.

[0104] 2. Surface abrasion resistance test

[0105] Abrasion resistance was tested using an abrasion testing machine (JM-IV, Pushen Testing Instruments Co., Ltd.) according to national standard GB / T 17657-2022. Before testing, all specimens and abrasive cloth were placed at a temperature of 23℃ and a relative humidity of 50% for at least 72 hours. 100mm × 100mm samples were fixed on the abrasion testing machine and loaded with two (4.9±0.2) N grinding wheels. The test was stopped after grinding for 350 revolutions, the surface condition of the specimens was observed, and the weight loss of the samples was recorded. Three samples per group were used for standard testing.

[0106] 3. Surface scratch resistance test

[0107] Scratch resistance was tested using a scratch tester (HY-V, Shanghai Tianchen Modern Environmental Technology Co., Ltd.) according to national standard GB / T 17657-2022. Before testing, all specimens and abrasive cloth were placed at 23℃ and 50% relative humidity for at least 72 hours. A 100mm × 100mm sample was fixed on the scratch tester, and a diamond needle was used to scratch the surface of the specimen under a load of 2N. After scratching, the specimen was placed at 23℃ and 50% relative humidity for 24 hours. The scratched areas on the specimen surface were observed.

[0108] 4. Surface crack resistance test

[0109] Surface crack resistance was tested according to GB / T 17657-2022 to evaluate the specimen's adaptability to rapid changes in environment such as temperature and humidity. A 250mm × 250mm sample was placed in a 70℃ forced-air drying oven for 24 hours. The specimen was then removed and placed in an environment of 23℃ and 50% relative humidity for 24 hours, after which surface changes were observed.

[0110] Table 1 Mechanical properties and formaldehyde emission of paper

[0111]

[0112] As shown in the table, it can be seen that the tensile strength of the impregnated paper prepared in the examples is higher than that of the decorative base paper (11.87 MPa) and comparable to that of the melamine impregnated paper. Furthermore, the elongation at break of the impregnated paper is more than 5 times that of the decorative base paper (0.81%) and more than 9 times that of the melamine impregnated paper (0.47%), indicating that the impregnated paper has good flexibility.

[0113] Figure 1 The figures show the actual images of the high-performance, high-flexibility formaldehyde-free impregnated paper, decorative base paper, and melamine impregnated paper prepared in Example 4, where a is the decorative base paper, b is the melamine impregnated paper, and c is the high-performance, high-flexibility formaldehyde-free impregnated paper. As can be seen from the figures, the formaldehyde-free flexible impregnated paper has good flexibility.

[0114] Table 2 Physical and chemical properties of decorative engineered wood panels

[0115]

[0116]

[0117] Based on the failure of other performance parameters in comparative experiments 1 and 2, no further performance tests were conducted; " / " in the table indicates that no relevant tests were performed.

[0118] As shown in the table, the surface bonding strength test of the decorative engineered wood panel in Comparative Experiment 1 did not meet the national standard (≥0.6MPa). The surface bonding strength and surface abrasion resistance of the decorative engineered wood panels in Examples 1, 2, 3, 4, and 5 met the national standard (<80mg / 100r), the surface scratch resistance met the national standard (>1.5N, no more than 90% of the surface has continuous scratches), and the surface crack resistance met the national standard (no cracks, blistering, discoloration, or wrinkling).

[0119] According to GB / T15102-2017 "Impregnated Paper-Faced Fiberboard and Particleboard", the surface bonding strength, surface abrasion resistance, and surface scratch resistance of the manufactured veneer artificial board are qualified if the surface bonding strength is ≥0.60MPa, the surface abrasion resistance is <80mg / 100r, the surface scratch resistance is >1.5N, there are no continuous scratches exceeding 90% on the surface, and the surface crack resistance is free from cracks, blistering, discoloration, and wrinkling. It can be seen that the embodiment effectively controls the pH of the impregnated polyamide-chloropropane resin and the content of polyvinyl alcohol / melamine adhesive, thereby improving the performance of the environmentally friendly formaldehyde-free flexible impregnated paper.

[0120] Figure 2 Infrared spectra are shown; a is the decorative base paper, b is the first-impregnated paper prepared in step three of Example 4, and c is the high-performance, highly flexible, formaldehyde-free impregnated film paper prepared in step three of Example 4. Infrared analysis was used to analyze the structural changes of the impregnated decorative paper. Compared to the decorative base paper (a), the first-impregnated PAE resin impregnated paper (b) showed a change in structure at 1639 cm⁻¹. -1 The C=O absorption peak becomes stronger at 1550 cm⁻¹. -1 The absorption peak of amide II (NH) becomes stronger at 1727 cm⁻¹. -1 The peaks at the points represent characteristic ester bonds formed between the nitrogen-butyl groups of PAE resin and the carboxyl groups of cellulose, as well as the tensile vibrations of ester bonds formed between the carboxyl groups at the ends of the polyamide chains and the nitrogen-butyl groups in PAE. This demonstrates that the PAE resin was successfully impregnated into the base paper, forming the first network structure. The impregnated paper after secondary impregnation with PVA / MA adhesive, at 3000 cm⁻¹... -1 ~3650cm -1 The broadening of the OH peak is due to the hydrogen bonding between the impregnated PAE decorative paper and PVA / MA. (1550 cm⁻¹) -1 The peak value of the NH bond becomes stronger; 800cm -1 ~847cm -1 The peak at this location is the triazine ring absorption peak of MA. This indicates that the PVA / MA adhesive was successfully coated onto the decorative paper impregnated with PAE resin, forming a chemically and physically combined double cross-linked network structure through hydrogen bond supramolecular cross-linking, thus forming the impregnated film paper (c).

[0121] Figure 3The image shows a physical picture of the polyvinyl alcohol / melamine adhesive prepared in Example 2; as can be seen from the picture, the adhesive is highly transparent.

[0122] Figure 4 The figures show actual images of the decorative base paper and the impregnated film paper. a is the decorative base paper, and b is the high-performance, highly flexible, formaldehyde-free impregnated film paper prepared in Example 2. As can be seen from the figures, the adhesive prepared in the example has high transparency and does not affect the paper texture.

Claims

1. A method for preparing a high-performance, highly flexible, formaldehyde-free impregnated adhesive film paper, characterized in that... It is done in the following steps:

1. Under conditions of 500 rpm to 1000 rpm, a NaOH solution with a concentration of 1 mol / L to 3 mol / L is added dropwise to the polyamide epichlorohydrin resin until the pH value is 7 to 11, thereby obtaining the pH-adjusted polyamide epichlorohydrin resin; the solid content of the polyamide epichlorohydrin resin is 5% to 20%.

2. Dissolve polyvinyl alcohol in distilled water, then add melamine, and react for 1 to 7 hours at a temperature of 90℃~100℃ and a stirring speed of 300rpm~600rpm. Finally, cool to room temperature to obtain polyvinyl alcohol / melamine adhesive. The polyvinyl alcohol / melamine adhesive contains 5% to 20% polyvinyl alcohol by mass; the polyvinyl alcohol / melamine adhesive contains 0.1% to 2% melamine by mass.

3. At room temperature, the decorative base paper is first impregnated in the pH-adjusted polyamide epichlorohydrin resin for 2 min to 10 min, and then dried to obtain a first-impregnated paper. At room temperature, the first-impregnated paper is then impregnated in polyvinyl alcohol / melamine adhesive for 2 min to 5 min, and then dried to obtain a high-performance, high-flexibility, formaldehyde-free impregnated film paper. The drying process specifically involves drying at a temperature of 50℃ to 90℃ for 10 to 15 minutes.

2. The application of the high-performance, highly flexible, formaldehyde-free impregnated paper prepared according to claim 1, characterized in that... It is used as a finishing material for engineered wood panels.

3. The application of the high-performance, high-flexibility, formaldehyde-free impregnated film paper according to claim 2, characterized in that... When used as a veneer material for engineered wood panels, it is specifically carried out in the following steps: High-performance, high-flexibility, formaldehyde-free impregnated paper is water-activated to obtain activated impregnated paper. The activated impregnated paper is then applied to the surface of the engineered wood panel, and finally hot-pressed to obtain the decorative engineered wood panel.

4. The application of the high-performance, high-flexibility, formaldehyde-free impregnated film paper according to claim 3, characterized in that... The water activation treatment is specifically carried out according to the following steps: at room temperature, with a coating amount of 0.1 g / cm³. 2 ~1g / cm 2 Water is applied to the surface of the high-performance, highly flexible, formaldehyde-free impregnated adhesive film to be pasted, and left to stand for 1 to 3 minutes; the hot pressing is specifically carried out at a hot pressing temperature of 170℃ to 230℃ and a hot pressing pressure of 1MPa to 3MPa for 10 seconds to 3 minutes.

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