A polyurethane honeycomb paper core composite board and a preparation method thereof

Abstract

The application relates to the field of paperboard, in particular to a polyurethane honeycomb paper core composite board and a preparation method thereof, wherein a glass fiber layer is arranged on the upper and lower surfaces of a corrugated paper core to prepare pretreated paperboard; foaming slurry is prepared by using modified polyurethane foaming emulsion and composite hybrid lignin, and then the foaming slurry is sprayed on the upper and lower surfaces of the pretreated paperboard to be molded; hybrid lignin is prepared by in-situ generation of nano zinc oxide on micron lignin; a benzisothiazolinone derivative containing a carboxyl group is esterified and grafted; the modified polyurethane foaming emulsion is prepared by using phthalic anhydride polyester polyol, polyneopentyl glycol adipate, epoxy resin E20 and isophorone diisocyanate as raw materials, dimethylol propionic acid and 1,4-butanediol as chain extenders, trimethylol phosphate as a crosslinking agent, a benzisothiazolinone derivative containing a carboxyl group as an end-capping agent, and triethylamine as a neutralizing agent; and the composite emulsion is emulsified by adding ammonium stearate as a foaming agent.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of paperboard, in particular to a polyurethane honeycomb paper core composite board and a preparation method thereof. BACKGROUND

[0002] With the development of industry, the emergence of a large number of energy-saving and new energy vehicles, people's demand for lightweight, low energy consumption, high safety of the car is growing, the production of lightweight automotive interior parts is the current industry hotspot. For example, the sun visor, trunk cover, hat rack and other common automotive interior parts are mostly made of honeycomb paper core composite board as the base material, and the surface is hot-pressed with fabric to prepare.

[0003] However, the existing honeycomb paper core composite board on the market has the advantages of environmental protection, light weight, etc., but also has the problems of poor impact resistance, poor moisture resistance and poor antibacterial property, which seriously affects the use effect. SUMMARY

[0004] The purpose of the present application is to provide a polyurethane honeycomb paper core composite board and a preparation method thereof to solve the problems in the prior art.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme:

[0006] A preparation method of a polyurethane honeycomb paper core composite board, comprising the following steps:

[0007] S1: glass fiber layers are arranged on the upper and lower surfaces of the corrugated paper core, and hot pressing is performed to obtain a pretreated paperboard;

[0008] S2: a foaming slurry is prepared using modified polyurethane foaming emulsion and composite hybrid lignin;

[0009] S3: the foaming slurry is sprayed on the upper and lower surfaces of the pretreated paperboard, and mold forming is performed to obtain a polyurethane honeycomb paper core composite board.

[0010] Further, the working conditions of mold forming are as follows: the temperature is 110-120 DEG C, and the pressure is 30-35 bar.

[0011] Further, in the foaming slurry, the mass ratio of the composite hybrid lignin to the modified polyurethane foaming emulsion is 8-12%.

[0012] Further, the preparation of the modified polyurethane foaming emulsion comprises the following steps:

[0013] The benzene anhydride polyester polyol, polyhexanedioic acid neopentyl glycol ester, and epoxy resin E20 are mixed, heated to 110°C for 1 h, cooled to 88-92°C, and then isophorone diisocyanate and dibutyltin dilaurate are added and kept for 1-2 h to obtain a prepolymer; the prepolymer is cooled to 78-82°C, and then dimethylolpropionic acid is added and stirred for 1-2 h, 1,4-butanediol and trimethylol phosphate are added, and stirred for 2-3 h, and then the mixture is cooled to 55-60°C, and the carboxyl-containing benzisothiazolinone derivative is added and stirred for 1-2 h, and then triethylamine and deionized water are added, emulsified, and then ammonium stearate is added and stirred to obtain a modified polyurethane foaming emulsion.

[0014] Further, the preparation of the composite hybrid lignin comprises the following steps:

[0015] 1) The alkaline lignin is ground and passed through a 200-mesh sieve to obtain micron lignin powder; under a nitrogen atmosphere, the micron lignin powder is mixed with deionized water, ultrasonically stirred, and then a mixture of zinc acetate dihydrate and deionized water is added, and the pH is adjusted to 8.9-9.1 with sodium hydroxide solution, and then heated to 88-92°C in an oil bath for 10-12 h, washed with deionized water, dialyzed in deionized water for 3 d, freeze-dried, and ground to obtain hybrid lignin;

[0016] 2) Under a nitrogen atmosphere, the carboxyl-containing benzisothiazolinone derivative is mixed with N,N-dimethylformamide, and then a mixture of hybrid lignin, p-toluenesulfonic acid, and N,N-dimethylformamide is added, and then kept at 70-80°C for 5-6 h to obtain the composite hybrid lignin.

[0017] Further, the mass ratio of ammonium stearate to the composite emulsion is 3%.

[0018] Further, the mass ratio of the carboxyl-containing benzisothiazolinone derivative to the hybrid lignin is 7:15.

[0019] Further, the preparation of the carboxyl-containing benzisothiazolinone derivative comprises the following steps:

[0020] (1) Benzisothiazolinone, potassium carbonate, and N,N-dimethylformamide are mixed, and then 6-bromo-1-hexene is added, and then heated to 78-82°C for 4-5 h, and then cooled, and then deionized water is added, and then extracted with ethyl acetate, and then dried with anhydrous sodium sulfate, and then filtered and rotary evaporated, and then chromatography column purification is performed with petroleum ether and ethyl acetate in a volume ratio of 3:1 to obtain a double-bond-containing N-substituted benzisothiazolinone compound;

[0021] (2) mixing acryloxypropyl cage polysilsesquioxane, 2,5-dimercaptoterephthalic acid, double bond containing N-substituted benzisothiazolinone compound, tetrahydrofuran, adding 2,2-dimethoxy-2-phenylphenylethanone, ultraviolet light curing treatment, adding anhydrous sodium carbonate, incubating at 18-25 DEG C for 1-2h, rotary evaporation, washing, drying, to obtain a carboxyl-containing benzisothiazolinone derivative.

[0022] Further, the working conditions of the ultraviolet light curing treatment are: irradiation under 365nm ultraviolet light for 20-30min.

[0023] The present application has the following beneficial effects:

[0024] The present application provides a kind of polyurethane honeycomb paper core composite board and preparation method thereof, by optimizing composition and process, preparation obtains the polyurethane honeycomb paper core composite board of good mechanical strength, high flame retardancy, excellent antibacterial and water resistance.

[0025] In order to give the composite board excellent bending and compression strength, glass fiber layer is arranged on the upper and lower surfaces of the corrugated paper core to prepare pretreated paperboard;Foaming slurry is prepared by using modified polyurethane foaming emulsion and composite hybrid lignin, and then foaming slurry is sprayed on the upper and lower surfaces of the pretreated paperboard, and the composite board is formed by molding, so that the composite board has excellent flame retardancy, antibacterial property, water resistance, aging resistance.

[0026] In the foaming slurry, composite hybrid lignin is introduced as a filler, and in the present application, alkaline lignin, an environmentally friendly and renewable antibacterial agent, is used as a raw material. However, there are limitations in the antibacterial property when directly introduced. In the present application, nanometer zinc oxide is generated in situ on micron lignin by using a hydrothermal method to prepare hybrid lignin. The multi-size hybrid lignin is beneficial to improve the corrosion resistance and aging resistance of the composite board. In order to improve the uniformity of the dispersion of the hybrid lignin in the formed polyurethane, the hybrid lignin is modified. The hydroxyl groups on the surface of the hybrid lignin are esterified and grafted with carboxyl-containing benzisothiazolinone derivatives. The carboxyl-containing benzisothiazolinone derivatives are synthesized by using benzisothiazolinone, which has good bactericidal property and safety, as a raw material, and then through one-step nucleophilic substitution with bromoalkene. Then, through photo-click reaction of mercapto-double bond, 2,5-dimercaptoterephthalic acid and acryloxypropyl cage polysilsesquioxane are prepared together. The introduction of acryloxypropyl cage polysilsesquioxane improves the thermal stability and water resistance of the composite board. The introduction of multiple active sites improves the bonding strength of the composite board with the pretreated paperboard.

[0027] The modified polyurethane foaming emulsion is prepared by using phthalic anhydride polyester polyol, polyhexanedioic acid neopentyl glycol ester, epoxy resin E20 and isophorone diisocyanate as raw materials, a prepolymer is obtained under the catalysis of dibutyltin dilaurate, then dimethylol propionic acid and 1,4-butanediol are used as chain extenders, trimethylol phosphate is used as a crosslinking agent, a benzisothiazolinone derivative containing a carboxyl group is used as a capping agent, and triethylamine is used as a neutralizing agent, a composite emulsion is prepared by emulsification, and ammonium stearate is added as a foaming agent in the composite emulsion, so that the modified polyurethane foaming emulsion as a foaming slurry base material is environmentally friendly, flame-retardant, antibacterial and water-resistant, so as to improve the flame-retardant, antibacterial and water-resistant properties of the composite board, thereby prolonging the service life of the composite board. DETAILED DESCRIPTION

[0028] The technical solutions in the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0029] It should be noted that if the present application involves directional indications such as up, down, left, right, front, back in the embodiments, the directional indications are only used to explain the relative position relationship, movement condition and the like between components in a certain posture, and if the certain posture changes, the directional indications also change accordingly. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that the technical solutions can be realized by those skilled in the art, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0030] The technical solutions of the present application will be further described in detail below in combination with specific embodiments. It should be understood that the following embodiments are only used to explain the present application and not to limit the present application.

[0031] Embodiment 1: A preparation method of a polyurethane honeycomb paper core composite board, comprising the following steps:

[0032] S1: Glass fiber layers are arranged on the upper and lower surfaces of the corrugated paper core, and hot pressing is performed to obtain a pretreated paper board;

[0033] S2: Foaming slurry is prepared by using modified polyurethane foaming emulsion and composite hybrid lignin;

[0034] The mass ratio of the composite hybrid lignin to the modified polyurethane foaming emulsion is 8%;

[0035] The preparation of the modified polyurethane foaming emulsion comprises the following steps:

[0036] Mixing 15 g of phthalic anhydride polyester polyol, 7.5 g of polyhexanedioic acid neopentyl glycol ester, 1.6 g of epoxy resin E20, heating to 110°C for 1 h, cooling to 88°C, adding 12 g of isophorone diisocyanate, 2 drops of dibutyltin dilaurate, and keeping for 1 h to obtain a prepolymer; cooling the prepolymer to 78°C, adding 1.1 g of dimethylolpropionic acid and stirring for 1 h, adding 1.4 g of 1,4-butanediol, 0.3 g of trimethylol phosphate, and stirring for 2 h, cooling to 55°C, adding 1.8 g of carboxyl-containing benzisothiazolinone derivative and stirring for 1 h, cooling to 38°C, adding 0.4 g of triethylamine, adding deionized water, and emulsifying for 1 h to obtain a composite emulsion with a solid content of 38%, adding ammonium stearate, and stirring to obtain a modified polyurethane foaming emulsion;

[0037] In the preparation of the modified polyurethane foaming emulsion, the mass ratio of ammonium stearate to the composite emulsion is 3%;

[0038] The preparation of the composite hybrid lignin comprises the following steps:

[0039] 1) Grinding the alkaline lignin through a 200-mesh sieve to obtain micron lignin powder; mixing 1 g of micron lignin powder and 99 mL of deionized water under a nitrogen atmosphere, stirring by ultrasonic, adding a mixture of 0.3 g of zinc acetate dihydrate and 20 mL of deionized water, adjusting the pH to 8.9 with sodium hydroxide solution, heating to 88°C in an oil bath for 12 h, washing with deionized water, dialyzing in deionized water for 3 d, freeze-drying, and grinding to obtain hybrid lignin;

[0040] 2) Mixing 14 g of carboxyl-containing benzisothiazolinone derivative and 20 mL of N,N-dimethylformamide under a nitrogen atmosphere, adding a mixture of 30 g of hybrid lignin, 0.8 g of p-toluenesulfonic acid, and 30 mL of N,N-dimethylformamide, keeping at 70°C for 6 h to obtain a composite hybrid lignin;

[0041] The preparation of the carboxyl-containing benzisothiazolinone derivative comprises the following steps:

[0042] (1) Mixing 1.51 g of benzisothiazolinone, 1.38 g of potassium carbonate, and 20 mL of N,N-dimethylformamide, adding 1.96 g of 6-bromo-1-hexene, heating to 78°C for 5 h, cooling, adding 50 mL of deionized water, extracting with ethyl acetate, drying with anhydrous sodium sulfate, filtering, rotary evaporating, and purifying by chromatography column with petroleum ether and ethyl acetate in a volume ratio of 3:1 to obtain a double-bond-containing N-substituted benzisothiazolinone compound;

[0043] (2) 3.6 g of acryloxypropyl cage polysilsesquioxane, 2.4 g of 2,5-dimercaptoterephthalic acid, 3.2 g of a double-bond-containing N-substituted benzisothiazolinone compound, 30 mL of tetrahydrofuran were mixed, 0.2 g of 2,2-dimethoxy-2-phenylphenylacetophenone was added, and irradiation was performed under 365 nm ultraviolet light for 20 min, 0.5 g of anhydrous sodium carbonate was added, and incubation was performed at 18°C for 2 h, and rotary evaporation, washing, and drying were performed to obtain a benzisothiazolinone derivative containing a carboxyl group;

[0044] S3: Spraying foaming slurry on the upper and lower surfaces of the pretreated paperboard, and molding to obtain a polyurethane honeycomb paper core composite board; the working conditions of molding are as follows: temperature is 110°C, and pressure is 35 bar.

[0045] Embodiment 2: A preparation method of a polyurethane honeycomb paper core composite board, comprising the following steps:

[0046] S1: Glass fiber layers were arranged on the upper and lower surfaces of the corrugated paper core, and hot pressing was performed to obtain a pretreated paperboard;

[0047] S2: Foaming slurry was prepared by using modified polyurethane foaming emulsion and composite hybrid lignin;

[0048] The mass ratio of the composite hybrid lignin to the modified polyurethane foaming emulsion is 10%;

[0049] The preparation of the modified polyurethane foaming emulsion comprises the following steps:

[0050] 15 g of phthalic anhydride polyester polyol, 7.5 g of polyhexanedioic acid neopentyl glycol ester, and 1.6 g of epoxy resin E20 were mixed, the temperature was increased to 110°C and incubated for 1 h, the temperature was decreased to 90°C, 12 g of isophorone diisocyanate, 2 drops of dibutyltin dilaurate were added, and incubation was performed for 1.5 h to obtain a prepolymer; the prepolymer was cooled to 80°C, 1.1 g of dimethylolpropionic acid was added and stirred for 1.5 h, 1.4 g of 1,4-butanediol and 0.3 g of trimethylol phosphate were added, and stirring was performed for 2.5 h, the temperature was decreased to 58°C, 1.8 g of benzisothiazolinone derivative containing a carboxyl group was added and stirred for 1.5 h, the temperature was decreased to 40°C, 0.4 g of triethylamine was added, deionized water was added, and emulsification was performed for 1 h to obtain a composite emulsion with a solid content of 38%, and then ammonium stearate was added and stirred to obtain a modified polyurethane foaming emulsion;

[0051] In the preparation of the modified polyurethane foaming emulsion, the mass ratio of ammonium stearate to the composite emulsion is 3%;

[0052] The preparation of the composite hybrid lignin comprises the following steps:

[0053] 1) grinding the alkaline lignin, passing through a 200 mesh sieve to obtain micron lignin powder; mixing 1 g of micron lignin powder, 99 mL of deionized water under a nitrogen atmosphere, ultrasonic stirring, adding a mixture of 0.3 g of zinc acetate dihydrate, 20 mL of deionized water, adjusting the pH to 9 with sodium hydroxide solution, warming to 90°C oil bath for 11 h, washing with deionized water, dialysis in deionized water for 3 d, freeze-drying, grinding to obtain hybrid lignin;

[0054] 2) mixing 14 g of carboxyl-containing benzisothiazolinone derivative, 20 mL of N,N-dimethylformamide under a nitrogen atmosphere, adding a mixture of 30 g of hybrid lignin, 0.8 g of p-toluenesulfonic acid, 30 mL of N,N-dimethylformamide, incubating at 75°C for 5.5 h to obtain a composite hybrid lignin;

[0055] The preparation of the carboxyl-containing benzisothiazolinone derivative includes the following steps:

[0056] (1) mixing 1.51 g of benzisothiazolinone, 1.38 g of potassium carbonate, 20 mL of N,N-dimethylformamide, adding 1.96 g of 6-bromo-1-hexene, warming to 80°C for 4.5 h, cooling, adding 50 mL of deionized water, extracting with ethyl acetate, drying with anhydrous sodium sulfate, filtering, rotary evaporation, and purifying with a chromatography column with a volume ratio of 3:1 petroleum ether to ethyl acetate to obtain a double bond-containing N-substituted benzisothiazolinone compound;

[0057] (2) mixing 3.6 g of acryloyloxypropyl cage polysilsesquioxane, 2.4 g of 2,5-dimercaptoterephthalic acid, 3.2 g of double bond-containing N-substituted benzisothiazolinone compound, 30 mL of tetrahydrofuran, adding 0.2 g of 2,2-dimethoxy-2-phenylacetophenone, irradiating under 365 nm ultraviolet light for 25 min, adding 0.5 g of anhydrous sodium carbonate, incubating at 20°C for 1.5 h, rotary evaporation, washing, and drying to obtain a carboxyl-containing benzisothiazolinone derivative;

[0058] S3: spraying foaming slurry on the upper and lower surfaces of the pretreated paperboard, and molding to obtain a polyurethane honeycomb paper core composite board; the working conditions of molding are: temperature is 115°C, and pressure is 32 bar.

[0059] Example 3: a preparation method of a polyurethane honeycomb paper core composite board, including the following steps:

[0060] S1: arranging a glass fiber layer on the upper and lower surfaces of the corrugated paper core, and hot pressing to obtain a pretreated paperboard;

[0061] S2: preparing foaming slurry with modified polyurethane foaming emulsion and composite hybrid lignin;

[0062] The mass ratio of the composite hybrid lignin to the modified polyurethane foaming emulsion is 12%;

[0063] The preparation of the modified polyurethane foaming emulsion comprises the following steps:

[0064] 15 g phthalic anhydride polyester polyol, 7.5 g polyhexanedioic acid neopentyl glycol ester, 1.6 g epoxy resin E20 are mixed, heated to 110°C for 1 h, cooled to 92°C, 12 g isophorone diisocyanate, 2 drops of dibutyltin dilaurate are added, and the temperature is kept for 2 h to obtain a prepolymer; the prepolymer is cooled to 82°C, 1.1 g of dimethylol propionic acid is added and stirred for 2 h, 1.4 g of 1,4-butanediol, 0.3 g of trimethylol phosphate is added and stirred for 3 h, cooled to 60°C, 1.8 g of carboxyl-containing benzisothiazolinone derivative is added and stirred for 2 h, cooled to 42°C, 0.4 g of triethylamine is added, deionized water is added, and emulsified for 1 h to obtain a composite emulsion with a solid content of 38%, then ammonium stearate is added and stirred to obtain a modified polyurethane foaming emulsion;

[0065] In the preparation of the modified polyurethane foaming emulsion, the mass ratio of ammonium stearate to the composite emulsion is 3%;

[0066] The preparation of the composite hybrid lignin comprises the following steps:

[0067] 1) The alkaline lignin is ground and passed through a 200-mesh sieve to obtain micron lignin powder; 1 g of micron lignin powder and 99 mL of deionized water are mixed under a nitrogen atmosphere, ultrasonic stirring is performed, a mixture of 0.3 g of zinc acetate dihydrate and 20 mL of deionized water is added, the pH is adjusted to 9.1 with sodium hydroxide solution, the temperature is raised to 92°C in an oil bath and kept for 10 h, washed with deionized water, dialyzed in deionized water for 3 d, and freeze-dried and ground to obtain hybrid lignin;

[0068] 2) Under a nitrogen atmosphere, 14 g of carboxyl-containing benzisothiazolinone derivative and 20 mL of N,N-dimethylformamide are mixed, a mixture of 30 g of hybrid lignin, 0.8 g of p-toluenesulfonic acid, and 30 mL of N,N-dimethylformamide is added, and the temperature is kept at 80°C for 5 h to obtain composite hybrid lignin;

[0069] The preparation of the carboxyl-containing benzisothiazolinone derivative comprises the following steps:

[0070] (1) 1.51 g of benzisothiazolinone, 1.38 g of potassium carbonate, and 20 mL of N,N-dimethylformamide are mixed, 1.96 g of 6-bromo-1-hexene is added, the temperature is raised to 82°C and kept for 4 h, cooled, 50 mL of deionized water is added, extracted with ethyl acetate, dried with anhydrous sodium sulfate, filtered, rotary evaporated, and purified by chromatography column with petroleum ether and ethyl acetate in a volume ratio of 3:1 to obtain N-substituted benzisothiazolinone compound containing a double bond;

[0071] (2) 3.6 g of acryloxypropyl cage polysilsesquioxane, 2.4 g of 2,5-dimercaptoterephthalic acid, 3.2 g of a double bond-containing N-substituted benzisothiazolinone compound, 30 mL of tetrahydrofuran were mixed, 0.2 g of 2,2-dimethoxy-2-phenylphenylacetophenone was added, and irradiation was performed under 365 nm ultraviolet light for 30 min. 0.5 g of anhydrous sodium carbonate was added, and incubation was performed at 25°C for 1 h. After rotary evaporation, washing, and drying, a benzisothiazolinone derivative containing a carboxyl group was obtained;

[0072] S3: A polyurethane honeycomb paper core composite board was obtained by spraying foaming slurry on the upper and lower surfaces of the pretreated paper board and molding. The working conditions of the molding were as follows: temperature was 120°C, and pressure was 30 bar.

[0073] Comparative Example 1: Example 3 was used as a control group. In the preparation of the modified polyurethane foaming emulsion, the benzisothiazolinone derivative containing a carboxyl group was not added, and other procedures were normal.

[0074] Comparative Example 2: Example 3 was used as a control group. Alkaline lignin was used to replace the composite hybrid lignin, and other procedures were normal.

[0075] Comparative Example 3: Example 3 was used as a control group. The benzisothiazolinone derivative containing a carboxyl group was not prepared, and other procedures were normal.

[0076] In the above examples and comparative examples, the thickness of the foaming slurry sprayed on the upper and lower surfaces of the pretreated paper board was 0.2 mm.

[0077] The sources of the raw materials used in the above examples and comparative examples are as follows (only as an exemplary example):

[0078] Epoxy resin E20 CYD-011: Balin Petrochemical; Glass fiber layer (04 glass fiber cloth): Hubei Chengfeng Chemical Co., Ltd.; Corrugated paper core (3 layers of B corrugated, thickness of 3mm): Dongguan Jingfu Paper Product Co., Ltd.; Phthalic anhydride polyester polyol JS1364: Hubei Jusheng Technology Co., Ltd.; Ammonium stearate 1002-89-7, polyneopentyl glycol adipate (99%): Hubei Shixing Chemical Co., Ltd.; Trimethylol phosphate 1067-12-5: (Alpha) Zhengzhou Alpha Chemical Co., Ltd.; p-Toluenesulfonic acid 104-15-4: Wuhan Jixingyibang Biological Technology Co., Ltd.; Acryloxypropyl cage polysilsesquioxane MA0735: Changsha Baxi Instrument Co., Ltd.; Isophorone diisocyanate I109582, dibutyltin dilaurate D100274, dimethylol propionic acid B104539, 1,4-butanediol B110391, triethylamine T103285, alkaline lignin L330880, zinc dihydroxide Z110777, N,N-dimethylformamide D111999, benzisothiazolinone B107479, 6-bromo-1-hexene B122541, 2,5-dimercaptoterephthalic acid B300649, tetrahydrofuran T431413, 2,2-dimethoxy-2-phenylacetophenone B105178: Aladdin Reagent; Sodium hydroxide, potassium carbonate, ethyl acetate, anhydrous sodium sulfate, petroleum ether, anhydrous sodium carbonate, analytical pure: National Pharmaceutical Group Reagent.

[0079] Performance test: the composite boards prepared in the examples and the comparative examples are subjected to performance test;

[0080] Flame retardancy: the sample is cut into a length of 10mm and a width of 2mm, and subjected to UL-94 vertical combustion flame retardant grade test; antibacterial property: the test strain is staphylococcus aureus, and the plate colony counting method is used for testing; water resistance: the sample size is 15mm in length and 5mm in width, the sample is irradiated with 365nm ultraviolet light for 72h, and then immersed in a 5% sodium chloride aqueous solution for 24h, and whether delamination, blistering and other defects occur is observed, and no any phenomenon is qualified; the results are shown in Table 1;

[0081] Table 1

[0082]

[0083] The application provides a polyurethane honeycomb paper core composite board and a preparation method thereof, and the polyurethane honeycomb paper core composite board with good mechanical strength, high flame retardancy, excellent antibacterial property and water resistance is prepared by optimizing components and processes.

[0084] Comparing example 3 with comparative example 1, the modified polyurethane foaming emulsion is prepared by using phthalic anhydride polyester polyol, polyhexanedioic acid neopentyl glycol ester, epoxy resin E20 and isophorone diisocyanate as raw materials, under the catalysis of dibutyltin dilaurate, to obtain a prepolymer, then using dimethylol propionic acid and 1,4-butanediol as chain extenders, using trimethylol phosphate as a crosslinking agent, using a carboxyl-containing benzisothiazolinone derivative as a blocking agent, wherein the carboxyl-containing benzisothiazolinone derivative is synthesized by using benzisothiazolinone with good bactericidal property and safety as raw material, and bromoalkene through one-step nucleophilic substitution to obtain N-substituted benzisothiazolinone compound containing double bond, and then using the thiol-double bond photo-click reaction to prepare 2,5-dimercapto terephthalic acid and acryloxypropyl cage polysilsesquioxane; using triethylamine as a neutralizing agent, emulsifying to prepare a composite emulsion, adding ammonium stearate as a foaming agent in the composite emulsion to obtain an environmentally friendly, flame-retardant, antibacterial and water-resistant modified polyurethane foaming emulsion as a foaming slurry base, so as to improve the flame retardance, antibacterial property and water resistance of the composite board, thereby prolonging the service life of the composite board.

[0085] Comparing example 3 with comparative example 2 and comparative example 3, the composite hybrid lignin is introduced as a filler in the foaming slurry, and in the present application, the environmentally friendly and renewable antibacterial agent alkali lignin is used as raw material, but direct introduction has limited antibacterial property, and the hybrid lignin is prepared by using hydrothermal method to generate in-situ nano zinc oxide on micron lignin, and the multi-size hybrid lignin is beneficial to improve the corrosion resistance of the composite board, in order to improve the uniformity of the hybrid lignin in the polyurethane after forming, the hybrid lignin is modified by using the hydroxyl group on the surface of the hybrid lignin to esterify grafting the carboxyl-containing benzisothiazolinone derivative; the introduction of acryloxypropyl cage polysilsesquioxane improves the thermal stability and water resistance of the composite board, and the introduction of multiple active sites improves the bonding strength with the pretreated paperboard.

[0086] The above is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made in the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A method for producing a polyurethane honeycomb paper core composite panel, characterized by, It comprises the following steps: S1: set the glass fiber layer on the upper and lower surfaces of the corrugated paper core, hot-press to obtain a pretreated paperboard; S2: prepare a foaming slurry by using modified polyurethane foaming emulsion and composite hybrid lignin; S3: spray the foaming slurry on the upper and lower surfaces of the pretreated paperboard, and mold to obtain a polyurethane honeycomb paper core composite board; The preparation of the modified polyurethane foaming emulsion comprises the following steps: Mix phthalic anhydride polyester polyol, polyhexanediol adipate, and epoxy resin E20, heat to 110°C for 1h, cool to 88-92°C, add isophorone diisocyanate and dibutyl tin dilaurate, and keep warm for 1-2h to obtain a prepolymer; cool the prepolymer to 78-82°C, add dimethylolpropionic acid and stir for 1-2h, add 1,4-butanediol and trimethylol phosphate and stir for 2-3h, cool to 55-60°C, add carboxyl-containing benzisothiazolinone derivative and stir for 1-2h, cool to 38-42°C, add triethylamine, add deionized water, emulsify, add ammonium stearate, and stir to obtain the modified polyurethane foaming emulsion; The preparation of the composite hybrid lignin comprises the following steps: 1) Grind the alkaline lignin and pass it through a 200-mesh sieve to obtain micron lignin powder; mix the micron lignin powder and deionized water under a nitrogen atmosphere, ultrasonic stir, add a mixture of zinc dihydroxyacetate and deionized water, adjust the pH to 8.9-9.1 with sodium hydroxide solution, heat to 88-92°C in an oil bath for 10-12h, wash with deionized water, dialyze in deionized water for 3d, freeze-dry, and grind to obtain hybrid lignin; 2) Mix carboxyl-containing benzisothiazolinone derivative and N,N-dimethylformamide under a nitrogen atmosphere, add a mixture of hybrid lignin, p-toluenesulfonic acid, and N,N-dimethylformamide, and keep warm at 70-80°C for 5-6h to obtain the composite hybrid lignin; The preparation of the carboxyl-containing benzisothiazolinone derivative comprises the following steps: (1) Mix benzisothiazolinone, potassium carbonate, and N,N-dimethylformamide, add 6-bromo-1-hexene, heat to 78-82°C and keep warm for 4-5h, cool, add deionized water, extract with ethyl acetate, dry with anhydrous sodium sulfate, filter, rotary evaporate, and purify with a chromatography column using petroleum ether and ethyl acetate in a volume ratio of 3:1 to obtain N-substituted benzisothiazolinone compound containing double bonds; (2) Mix acryloyloxypropyl cage polysilsesquioxane, 2,5-dimercaptoterephthalic acid, N-substituted benzisothiazolinone compound containing double bonds, and tetrahydrofuran, add 2,2-dimethoxy-2-phenylphenylethanone, ultraviolet light curing treatment, add anhydrous sodium carbonate, keep warm at 18-25°C for 1-2h, rotary evaporate, wash, and dry to obtain the carboxyl-containing benzisothiazolinone derivative.

2. The method for preparing a polyurethane honeycomb paper core composite board according to claim 1, characterized in that, The working conditions for mold forming are: temperature of 110-120°C and pressure of 30-35bar.

3. The method for preparing a polyurethane honeycomb paper core composite board according to claim 1, characterized in that, In the foaming slurry, the mass ratio of the composite hybrid lignin to the modified polyurethane foaming emulsion is 8-12%.

4. The method for preparing a polyurethane honeycomb paper core composite board according to claim 1, characterized in that, In the preparation of the modified polyurethane foaming emulsion, the mass ratio of ammonium stearate to the composite emulsion is 3%.

5. The method for preparing a polyurethane honeycomb paper core composite board according to claim 1, characterized in that, In the preparation of the composite hybrid lignin, the mass ratio of the carboxyl-containing benzisothiazolinone derivative to the hybrid lignin is 7:

15.

6. The method for preparing a polyurethane honeycomb paper core composite board according to claim 1, characterized in that, In the preparation of the carboxyl-containing benzisothiazolinone derivative, the working conditions of the ultraviolet light curing treatment are: irradiation under 365nm ultraviolet light for 20-30min.

7. A polyurethane honeycomb paper core composite panel, characterized by, Prepared according to the preparation method in any one of claims 1-6.

Images