Spraying process for improving color stability of impregnated paper

Abstract

The invention relates to the technical field of impregnated paper, in particular to a spraying process for improving color stability of impregnated paper, which comprises the following steps: step (1) pretreatment of melamine impregnated paper; (2) spraying the surface of the pretreated melamine impregnated paper with a spraying liquid; and (3) the sprayed impregnated paper is cured in a stepped curing mode, an interpenetrating network structure of a nano-cellulose skeleton and beta-cyclodextrin filling holes can be formed on the surface of the melamine impregnated paper through spraying liquid, a stable film layer structure is formed on the surface of the melamine impregnated paper, a color layer is protected and stabilized, and the surface of the melamine impregnated paper is protected. The color stability is greatly improved due to double protection of chemical removal of the antioxidant modified beta-cyclodextrin and physical shielding of the nano-zinc oxide.

Description

Technical Field

[0001] The present invention relates to the technical field of impregnated paper, and particularly to a spraying process for improving the color stability of impregnated paper. Background Art

[0002] Melamine impregnated paper is a special treated decorative material, which is widely used in the fields of furniture manufacturing, interior decoration, etc. At present, it is mainly obtained by impregnating the paper printed with colors or imitation wood grains in melamine solution and then drying. Since melamine impregnated paper is mainly used as a decorative material, such as the veneer on the surface of furniture, the color stability is very important. Otherwise, fading or discoloration over time will affect the appearance of the product. The main reason is that the degradation of organic pigments caused by ultraviolet rays and humid and hot environments results in fading or discoloration. Summary of the Invention

[0003] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, the abstract of the specification and the title of the invention of this application to avoid obscuring the purpose of this part, the abstract of the specification and the title of the invention, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0004] To achieve the above object, the present invention provides the following technical solution: A spraying process for improving the color stability of impregnated paper, which comprises the following steps: Step (1) Pretreatment of melamine impregnated paper; Step (2) Spraying the surface of the pretreated melamine impregnated paper with a spraying liquid; Step (3) Curing the sprayed impregnated paper by a stepwise curing method; Among them, the spraying liquid is composed of the following raw materials in parts by weight: Waterborne polyurethane resin 60 - 80 parts Aqueous solution of nanocellulose 15 - 20 parts Nano ZnO 1 - 3 parts Antioxidant modified β - cyclodextrin 1 - 2 parts Aminosilane coupling agent 0.1 - 0.5 part Aziridine crosslinking agent 0.3 - 0.8 part Defoaming agent 0.2 - 0.3 part Deionized water 20 - 50 parts.

[0005] Among them, the aminosilane coupling agent adopts KH - 550, the aziridine crosslinking agent adopts CARBODILITE V - 02, and the defoaming agent adopts TEGO 810.

[0006] Among them, the waterborne polyurethane resin is an aliphatic waterborne polyurethane with a solid content of 45-55%, and the waterborne polyurethane resin of model AH-1618 produced by Anhui Dawei Huatai New Material Technology Co., Ltd. can be used.

[0007] Preferably, the preparation method of the spraying liquid in step (1) is as follows: Step (1.1): Mix 60-80 parts of the waterborne polyurethane resin with 10-20 parts of deionized water and stir evenly to obtain a diluted waterborne polyurethane resin solution; add 1-3 parts of nano-ZnO to 7-9 parts by weight of deionized water and stir evenly, then add 0.1-0.5 part of amino silane coupling agent to obtain a nano-ZnO dispersion; add the above nano-ZnO dispersion, 1-2 parts of antioxidant-modified β-cyclodextrin, and 15-20 parts of nano-cellulose aqueous solution to the above diluted waterborne polyurethane resin solution and stir evenly to obtain a base liquid; Step (1.2): Add 0.3-0.8 part of aziridine crosslinking agent to the base liquid in step (1) and stir slowly; Step (1.3): Add deionized water to make the viscosity stable at 50-80 mPa·s, and then add 0.2-0.3 part of defoaming agent to defoam to obtain the spraying liquid.

[0008] Preferably, the preparation method of the antioxidant-modified β-cyclodextrin in step (1) is: dissolve 1-3 parts by weight of β-cyclodextrin, 0.3-0.5 part by weight of lipophilic antioxidant, and 0.5-0.8 part by weight of epoxy group silane coupling agent in a mixed solution of ethanol / water, stir at 60-65 °C for 8-10 hours, adjust the pH to 5 with acetic acid, and freeze-dry to obtain the antioxidant-modified β-cyclodextrin.

[0009] Among them, the volume ratio of ethanol to water is 8-7:2-3, the epoxy group silane coupling agent uses KH-560, and the lipophilic antioxidant uses butylated hydroxytoluene.

[0010] Preferably, the concentration of the carboxylated nano-cellulose aqueous solution in step (1) is 2-3%, the diameter is 10-50 nm, and the length is 0.5-2 μm.

[0011] Preferably, during the pretreatment in step (1), the melamine paper is treated by low-temperature plasma with a power of 50-55 W and a time of 30-40 s to increase the surface hydroxyl density by 40-50%.

[0012] Preferably, in step (2), the spraying is carried out at a speed of 1.5-2 m / min, a pressure of 0.5-0.7 MPa, the spraying distance is 20-30 cm, the film thickness is 8-12 μm, and the spraying is carried out by a high-pressure airless spraying machine with a nozzle diameter of 0.3 mm.

[0013] Preferably, in step (3) of curing: the first stage is cured at 60°C - 65°C for 5 - 10 minutes; the second stage: cured at 80 - 90°C for 10 - 15 minutes; the third stage: cured at 115 - 120°C for 20 - 25 minutes; to avoid the sudden drying of the glue solution resulting in the peeling or cracking of the color layer.

[0014] The synthetic fat-soluble antioxidant butylated hydroxytoluene in the antioxidant-modified β-cyclodextrin has strong hydrophobicity and is easily included by β-cyclodextrin, playing a slow-release role and being able to effectively exert antioxidant effects for a long time. The epoxy silane coupling agent undergoes chemical bonding with the hydroxyl groups (-OH) on the surface of the melamine paper, increasing the interfacial bonding force, reducing the risk of coating peeling, and stabilizing the color layer structure.

[0015] Nanocellulose can form a dense and highly transparent nanonetwork film (with a thickness of 100 - 500 nm), effectively blocking the penetration of oxygen and water vapor (the oxygen transmission rate is reduced by 30 - 50%), and slowing down the oxidation and deliquescence of pigments. The surface of CNF is rich in hydroxyl groups, and nanocellulose combines with melamine resin and paper fibers through hydrogen bonds, reducing the risk of coating peeling and stabilizing the color layer structure.

[0016] The silane coupling agent improves the interfacial bonding force, and the aziridine crosslinking agent improves the crosslinking degree of the bulk phase. The two work synergistically to optimize the adhesion and water resistance.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: A spraying process for improving the color stability of impregnated paper according to the present invention includes the following steps: step (1) pretreatment of the melamine impregnated paper; step (2) spraying the surface of the pretreated melamine impregnated paper with a spraying liquid; step (3) curing the sprayed impregnated paper by means of stepwise curing. The spraying liquid can form an interpenetrating network structure of a nanocellulose skeleton and β-cyclodextrin-filled pores on the surface of the melamine impregnated paper, forming a stable film layer structure on the surface of the melamine impregnated paper, protecting and stabilizing the color layer. The dual protection of the chemical scavenging of antioxidant-modified β-cyclodextrin and the physical shielding of nano-zinc oxide greatly improves the color stability. The slow-release effect of the antioxidant-modified β-cyclodextrin chemically extends the time of color stability. Detailed implementation manners

[0018] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following provides a detailed description of the specific implementation manners of the present invention.

[0019] Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0020] Secondly, the so-called "one embodiment" or "embodiment" herein refers to specific features, structures or characteristics that may be included in at least one implementation manner of the present invention. The "in one embodiment" that appears in different places in this specification does not all refer to the same embodiment, nor is it an individual or selectively mutually exclusive embodiment with other embodiments.

[0021] Embodiment 1

[0022] A spraying process for improving the color stability of impregnated paper, which comprises the following steps: Step (1) Pretreatment of melamine impregnated paper; Step (2) Spraying the surface of the pretreated melamine impregnated paper with a spraying liquid; Step (3) Curing the sprayed impregnated paper by means of stepwise curing; The preparation method of the spraying liquid in step (1) is as follows: Step (1.1) Mix 60 parts of waterborne polyurethane resin with 10 parts of deionized water and stir evenly to obtain a diluted waterborne polyurethane resin solution; add 1 nm ZnO to 7 parts by weight of deionized water and stir evenly, then add 0.1 part of amino silane coupling agent to obtain a nano ZnO dispersion; add the above nano ZnO dispersion, 1 part of antioxidant-modified β-cyclodextrin, and 15 parts of nano cellulose aqueous solution to the above diluted waterborne polyurethane resin solution, and stir evenly to obtain a base liquid; Step (1.2) Add 0.3 part of aziridine crosslinking agent to the base liquid in step (1) and stir slowly; Step (1.3) Add deionized water to make the viscosity stable at 50 mPa·s, and then add 0.2 part of defoaming agent to defoam to obtain a spraying liquid.

[0023] Among them, the amino silane coupling agent uses KH-550, the aziridine crosslinking agent uses CARBODILITE V-02, and the defoaming agent uses TEGO 810.

[0024] Among them, the waterborne polyurethane resin uses the waterborne polyurethane resin with the model number AH-1618 produced by Anhui Dawei Huatai New Material Technology Co., Ltd.

[0025] Among them, the preparation method of the antioxidant-modified β-cyclodextrin in step (1) is: dissolve 1 part by weight of β-cyclodextrin, 0.3 part by weight of fat-soluble antioxidant, and 0.5 part by weight of epoxy group silane coupling agent in a mixed solution of ethanol / water, stir for 8 hours at 60, adjust the pH = 5 with acetic acid, and freeze-dry to obtain antioxidant-modified β-cyclodextrin.

[0026] Among them, the volume ratio of ethanol to water is 8:3, the epoxy group silane coupling agent uses KH-560, and the fat-soluble antioxidant uses butylated hydroxytoluene.

[0027] Among them, in step (1), the concentration of the carboxylated nanocellulose aqueous solution is 2%, the diameter is 10 - 50 nm, and the length is 0.5 - 2 μm.

[0028] Among them, in step (1) during pretreatment, the melamine paper is treated by low-temperature plasma, with a power of 50 W and a time of 30.

[0029] Among them, in step (2), spraying is carried out at a speed of 1.5 m / min, a pressure of 0.5 Pa, a spraying distance of 20 cm, and a film thickness of 8 μm.

[0030] Among them, in step (3) curing: the first stage is cured at 60 °C for 10 minutes; the second stage: cured at 80 °C for 15 minutes; the third stage: cured at 115 °C for 20 minutes.

[0031] Example 2

[0032] A spraying process for improving the color stability of impregnated paper, which comprises the following steps: Step (1) Pretreatment of melamine impregnated paper; Step (2) Spraying the surface of the pretreated melamine impregnated paper with a spraying liquid; Step (3) Curing the sprayed impregnated paper by means of stepwise curing; Among them, the preparation method of the spraying liquid in step (1) is as follows: Step (1.1) Mix 70 parts of waterborne polyurethane resin with 15 parts of deionized water and stir evenly to obtain a diluted waterborne polyurethane resin solution; add 2 parts of nano-ZnO to 8 parts by weight of deionized water and stir evenly, then add 0.3 part of amino silane coupling agent to obtain a nano-ZnO dispersion; add the above nano-ZnO dispersion, 2 parts of antioxidant-modified β-cyclodextrin, and 18 parts of carboxylated nanocellulose aqueous solution to the above diluted waterborne polyurethane resin solution, and stir evenly to obtain a base liquid; Step (1.2) Add 0.6 part of aziridine crosslinking agent to the base liquid in step (1) and stir slowly; Step (1.3) Add deionized water to make the viscosity stable at 60 mPa·s, and then add 0.3 part of defoaming agent to defoam to obtain the spraying liquid.

[0033] Among them, the amino silane coupling agent uses KH-550, the aziridine crosslinking agent uses CARBODILITE V-02, and the defoaming agent uses TEGO 810.

[0034] Among them, the waterborne polyurethane resin uses the waterborne polyurethane resin with the model AH-1618 produced by Anhui Dawei Huatai New Material Technology Co., Ltd.

[0035] Among them, the preparation method of the antioxidant-modified β-cyclodextrin in step (1) is as follows: 2 parts by weight of β-cyclodextrin, 0.4 parts by weight of a fat-soluble antioxidant, and 0.7 parts by weight of an epoxy group-containing silane coupling agent are dissolved in a mixed solution of ethanol / water, stirred at 63 °C for 9 hours, adjusted to pH = 5 with acetic acid, and freeze-dried to obtain the antioxidant-modified β-cyclodextrin.

[0036] Among them, the volume ratio of ethanol to water is 7:2, the epoxy group-containing silane coupling agent is KH-560, and the fat-soluble antioxidant is butylated hydroxytoluene.

[0037] Among them, the concentration of the carboxylated nanocellulose aqueous solution in step (1) is 3%, the diameter is 10 - 50 nm, and the length is 0.5 - 2 μm.

[0038] Among them, during the pretreatment in step (1), the melamine paper is treated with low-temperature plasma, with a power of 53 W and a time of 35 s.

[0039] Among them, in step (2), spraying is carried out at a speed of 1.8 m / min, a pressure of 0.6 MPa, a spraying distance of 25 cm, and a film thickness of 10 μm.

[0040] Among them, in step (3), curing: the first stage is cured at 62 °C for 8 minutes; the second stage: cured at 85 °C for 12 minutes; the third stage: cured at 118 °C for 22 minutes.

[0041] Example 3

[0042] A spraying process for improving the color stability of impregnated paper, which includes the following steps: Step (1) Pretreatment of melamine impregnated paper; Step (2) Spraying the surface of the pretreated melamine impregnated paper with a spraying liquid; Step (3) Curing the sprayed impregnated paper by means of stepwise curing; Among them, the preparation method of the spraying liquid in step (1) is as follows: Step (1.1) Mix 80 parts of waterborne polyurethane resin with 20 parts of deionized water and stir evenly to obtain a diluted waterborne polyurethane resin solution; add 3 parts of nano-ZnO to 9 parts by weight of deionized water and stir evenly, then add 0.5 part of an amino group-containing silane coupling agent to obtain a nano-ZnO dispersion; add the above nano-ZnO dispersion, 2 parts of antioxidant-modified β-cyclodextrin, and 20 parts of nanocellulose aqueous solution to the above diluted waterborne polyurethane resin solution, and stir evenly to obtain a base liquid; Step (1.2) Add 0.8 part of an aziridine crosslinking agent to the base liquid in step (1) and stir slowly; Step (1.3) After adding deionized water to make the viscosity stable at 70 mPa·s, then add 0.3 part of an antifoaming agent to defoam and obtain the spraying liquid.

[0043] Among them, KH-550 is used as the amino silane coupling agent, CARBODILITE V-02 is used as the aziridine crosslinking agent, and TEGO 810 is used as the defoaming agent.

[0044] Among them, the waterborne polyurethane resin used is the waterborne polyurethane resin with the model AH-1618 produced by Anhui Dawei Huatai New Material Technology Co., Ltd.

[0045] Among them, the preparation method of the antioxidant-modified β-cyclodextrin in step (1) is as follows: Dissolve 3 parts by weight of β-cyclodextrin, 0.5 parts by weight of the fat-soluble antioxidant, and 0.8 parts by weight of the epoxy group-containing silane coupling agent in a mixed solution of ethanol / water, stir at 65 °C for 8 hours, adjust the pH to 5 with acetic acid, and freeze-dry to obtain the antioxidant-modified β-cyclodextrin.

[0046] Among them, the volume ratio of ethanol to water is 7:3, the epoxy group-containing silane coupling agent used is KH-560, and the fat-soluble antioxidant used is butylated hydroxytoluene.

[0047] Among them, the concentration of the carboxylated nanocellulose aqueous solution in step (1) is 3%, the diameter is 10 - 50 nm, and the length is 0.5 - 2 μm.

[0048] Among them, during the pretreatment in step (1), the melamine paper is treated by low-temperature plasma with a power of 55 W and a time of 40 s.

[0049] Among them, in step (2), spraying is carried out at a speed of 2 m / min, a pressure of 0.7 MPa, a spraying distance of 30 cm, and a film thickness of 12 μm.

[0050] Among them, in step (3), curing: The first stage is cured at 65 °C for [X] minutes; the second stage: cured at 90 °C for 10 minutes; the third stage: cured at 120 °C for 20 minutes.

[0051] Comparative Example 1

[0052] The difference between this example and Example 2 is that: Antioxidant-modified β-cyclodextrin is not used, that is, β-cyclodextrin is not modified with a fat-soluble antioxidant and an epoxy group-containing silane coupling agent, but ordinary β-cyclodextrin is used.

[0053] Comparative Example 2

[0054] The difference between this example and Example 2 is that: Antioxidant-modified β-cyclodextrin is directly deleted from the formula and process, that is, neither antioxidant-modified β-cyclodextrin nor ordinary β-cyclodextrin is used.

[0055] Comparative Example 3

[0056] The difference between this example and Example 2 is that: The carboxylated nanocellulose aqueous solution is not used.

[0057] The ultraviolet ray blocking rate at 400 nm is measured by UV-Vis spectroscopy (ASTM E308). For the weather resistance test c, the color change after UV irradiation is measured according to ASTM D4329 for 1000 h by QUV. After damp heat cycling (85 °C / 85% RH, 30 days), for chemical resistance, it is wiped 50 times with 10% NaOH solution and 100 times with ethanol.

[0058] Table 1

[0059] As can be seen from Table 1, for the products of the present invention, the ΔE values of color change after ultraviolet irradiation are all less than 1.5, and the ultraviolet ray blocking rates are all above 97%. This shows that the spraying process of the present invention greatly improves the anti-ultraviolet performance of the products and can maintain long-term color vividness.

[0060] In Comparative Example 1, only ordinary β-cyclodextrin is used without modification, resulting in a decrease in the ultraviolet ray blocking rate and a deterioration in the weather resistance test, and no significant changes are observed in other properties.

[0061] In Comparative Example 2, antioxidant-modified β-cyclodextrin is not used, and all properties decline significantly. Especially when observing the pattern appearance after 12 months, it can be clearly seen that this is due to the disappearance of the antioxidant effect of the antioxidant, the stable film layer of β-cyclodextrin, and the slow-release effect.

[0062] In Comparative Example 3, nano-cellulose aqueous solution is not used, and a stable film layer structure cannot be formed on the surface of the melamine impregnated paper, resulting in a decrease in the resistance to damp heat cycling and chemical resistance, and further an increase in the ΔE value of color change and a decrease in the ultraviolet ray blocking rate.

[0063] 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 the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A spraying process for improving the color stability of impregnated paper, characterized in that: It includes the following steps: Step (1) pretreatment of melamine impregnated paper; Step (2) spraying the spray liquid onto the surface of the pretreated melamine impregnated paper; Step (3) curing the sprayed impregnated paper by a step curing method; Wherein, the spraying liquid is composed of the following raw materials in parts by weight: 60-80 parts of waterborne polyurethane resin 15-20 parts of nanocellulose aqueous solution Nano ZnO 1-3 parts Antioxidant modified β-cyclodextrin 1-2 parts Aminosilane coupling agent 0.1-0.5 parts 0.3-0.8 parts of aziridine crosslinking agent Defoamer 0.2-0.3 parts 20-50 parts of deionized water.

2. A spraying process for improving the color stability of impregnated paper according to claim 1, characterized in that: The preparation method of the spraying liquid in step (1) is: Step (1.1) 60-80 parts of an aqueous polyurethane resin and 10-20 parts of deionized water are mixed and stirred uniformly to obtain a diluted aqueous polyurethane resin solution; 1-3 parts of nano ZnO are added to 7-9 parts by weight of deionized water and stirred uniformly, and then 0.1-0.5 parts of an aminosilane coupling agent are added to obtain a nano ZnO dispersion; the nano ZnO dispersion, 1-2 parts of an antioxidant-modified β-cyclodextrin, and 15-20 parts of a nano cellulose aqueous solution are added to the diluted aqueous polyurethane resin solution and stirred uniformly to obtain a base liquid; Step (1.2) Add 0.3-0.8 parts of aziridine crosslinking agent to the base liquid of step (1) and stir slowly; In step (1.3), deionized water is added to stabilize the viscosity at 50-80 mPa·s, and then 0.2-0.3 parts of a defoaming agent is added to defoam to obtain a spray liquid.

3. A spraying process for improving the color stability of impregnated paper according to claim 1, characterized in that: The preparation method of the antioxidant modified β-cyclodextrin in step (1) is as follows: 1-3 parts by weight of β-cyclodextrin, 0.3-0.5 parts by weight of a fat-soluble antioxidant, and 0.5-0.8 parts by weight of an epoxysilane coupling agent are dissolved in an ethanol / water mixture, stirred at 60-65° C. for 8-10 hours, adjusted to pH=5 with acetic acid, and freeze-dried to obtain the antioxidant modified β-cyclodextrin.

4. A spraying process for improving the color stability of impregnated paper according to claim 1, characterized in that: Step (1) The concentration of the carboxylated nanocellulose aqueous solution is 2-3%, the diameter is 10-50 nm, and the length is 0.5-2 μm.

5. The spraying process for improving the color stability of impregnated paper according to claim 1, characterized in that: In step (1), the melamine paper is treated with low-temperature plasma at a power of 50-55 W for 30-40 seconds during pretreatment.

6. The spraying process for improving the color stability of impregnated paper according to claim 1, characterized in that: Step (2) spraying is performed at a speed of 1.5-2 m / min, a pressure of 0.5-0.7 MPa, a spraying distance of 20-30 cm, and a film thickness of 8-12 μm.

7. The spraying process for improving the color stability of impregnated paper according to claim 1, characterized in that: Step (3) Curing: First step: curing at 60°C-65°C for 5-10 minutes; second step: curing at 80-90°C for 10-15 minutes; third step: curing at 115-120°C for 20-25 minutes.

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