A high-strength membrane paper material and preparation method thereof

Abstract

The present invention belongs to the technical field of packaging materials, and specifically relates to a high-strength film paper material and a preparation method thereof. The high-strength film paper material comprises, from bottom to top, a kraft paper layer, a polyurethane adhesive layer, and a polylactic acid-polybutylene terephthalate adipate composite film layer. The polyurethane adhesive is prepared by scientifically proportioning the present invention, which can improve the peel strength and tensile properties of the kraft paper layer and the polylactic acid-polybutylene terephthalate adipate composite film layer after bonding, thereby improving the mechanical properties of the composite film paper. The polyurethane adhesive can also improve the antibacterial properties of the polyurethane adhesive itself, thereby expanding the application range of paper-plastic composite films.

Description

Technical Field

[0001] The present invention belongs to the technical field of packaging materials, and in particular relates to a high-strength film paper material and a preparation method thereof. Background Art

[0002] Composite film is a polymer material widely used in packaging, printing, electronics, and other fields. As consumers demand increasingly higher quality and packaging, the market demand for composite films continues to grow, and their application prospects are very promising. In the packaging field, composite films can be used to package a variety of products, including food, medicine, and daily chemicals. With the continuous improvement of environmental awareness, biodegradable composite films will become a key trend in the future packaging industry. These new composite films can reduce the pollution caused by plastic waste, protect the environment, and promote sustainable development.

[0003] CN103538317A discloses a method for preparing a high-strength paper-plastic composite film. The technical solution uses an adhesive to compound a polyethylene film layer, an aluminum foil layer, a polyester film layer, and a kraft paper film layer, thereby significantly improving the tensile strength and heat-sealing performance of the composite film. However, the polyethylene film layer, the polyester film layer, and the adhesive are all non-degradable materials, which will have a lasting negative impact on the environment after use, thereby limiting the application prospects of the composite film. CN107902258A discloses a fully degradable paper-plastic composite film paper and its preparation process. The composite film paper is composed of a polylactic acid film layer, a bonding layer, and a paper layer. By carefully mixing an adhesive, preparing a polylactic acid film, carrying out a machine-made paper-plastic composite, and winding and aging, while ensuring that the composite film paper has environmental protection characteristics, its mechanical properties are also enhanced. However, the technical solution does not further study the peel strength of the composite film, thereby limiting the scope of application of the composite film.

[0004] Therefore, there is an urgent need for a high-strength composite membrane with good mechanical properties and environmental performance, so as to further expand the application range of the composite membrane. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, one of the objectives of the present invention is to provide a high-strength membrane paper material with good peel strength and mechanical properties.

[0006] One of the purposes of the present invention is achieved by the following technical solution:

[0007] A high-strength film paper material, comprising, from bottom to top, a kraft paper layer, a polyurethane adhesive layer, and a polylactic acid-polybutylene terephthalate adipate composite film layer;

[0008] The polylactic acid-polybutylene terephthalate adipate composite film layer is made of the following raw materials in parts by weight: 50-70 parts of polylactic acid, 30-50 parts of polybutylene terephthalate adipate, 0.8-1.5 parts of titanate coupling agent, 0.2-0.5 parts of 9,10-dihydroxyoctadecanoic acid, and 0.2-0.5 parts of epoxy soybean oil;

[0009] The polyurethane adhesive layer is made of the following raw materials in parts by weight: 50-80 parts of linolenic acid-linalool, 15-20 parts of polyisocyanate, 11-23 parts of hydrophilic agent, 2.5-3.5 parts of chain extender, 1-2 parts of catalyst, 2.5-3.0 parts of triethylamine, and 2.5-3.5 parts of silane coupling agent;

[0010] The structure of the linolenic acid-linalool is:

[0011]

[0012] Furthermore, the preparation process of linolenic acid-linalool comprises the following steps:

[0013] (1) Add α-linolenic acid, linalool, and p-toluenesulfonic acid to toluene, react at 110-125° C. for 12-16 hours, and treat to obtain intermediate 1; the structure of intermediate 1 is:

[0014]

[0015] (2) Add intermediate 1 to dichloromethane, cool to 0°C, then add m-chloroperbenzoic acid in batches. After the addition is complete, react at 0-10°C for 36-48 hours, and then treat to obtain intermediate 2; the structure of intermediate 2 is:

[0016]

[0017] (3) Add intermediate 2, betaine hydrochloride, and tert-butyl perbenzoate to toluene, react at 110-125° C. for 5-7 h, and obtain linolenic acid-linalool after treatment.

[0018] Furthermore, the molar ratio of α-linolenic acid, linalool and p-toluenesulfonic acid in step (1) is 1: (1.1-1.5): (0.6-0.75).

[0019] Furthermore, in step (2), the molar ratio of the intermediate 1 to m-chloroperbenzoic acid is 1:(5-6).

[0020] Furthermore, in step (3), the molar ratio of the intermediate 2, betaine hydrochloride, and tert-butyl perbenzoate is 1:(5-6):(15-20).

[0021] Furthermore, the polyisocyanate is one of trimethylhexamethylene diisocyanate (TMDI) and isophorone diisocyanate (IPDI); the hydrophilic agent is one of dimethylolpropionic acid, dimethylolbutyric acid, and 2-hydroxyethyl acrylate; the chain extender is glycerol; the catalyst is dibutyltin dilaurate; and the silane coupling agent is one of (3-glycidoxypropyl)methyldiethoxysilane and (3-glycidoxypropyl)triethoxysilane.

[0022] A second object of the present invention is to provide a method for preparing a high-strength membrane paper material.

[0023] The second object of the present invention is achieved by adopting the following technical solution:

[0024] The method for preparing the above-mentioned high-strength membrane paper material comprises the following steps:

[0025] S1: adding a polylactic acid-polybutylene terephthalate adipate blend into a casting machine to prepare the polylactic acid-polybutylene terephthalate adipate composite film layer through a casting process;

[0026] The preparation method of the polylactic acid-polybutylene terephthalate adipate blend comprises: mixing lactic acid, polybutylene terephthalate adipate, a titanate coupling agent, 9,10-dihydroxyoctadecanoic acid, and epoxy soybean oil, and then performing melt extrusion and granulation to obtain the blend;

[0027] S2: adding polyurethane adhesive into a glue tank, applying glue on the corona surface of the polylactic acid-polybutylene terephthalate adipate composite film layer, and drying to form a polyurethane adhesive layer;

[0028] The preparation method of the polyurethane adhesive comprises: mixing linolenic acid-linalool and a hydrophilic agent and stirring them uniformly, then adding a polyisocyanate and a catalyst to carry out a heating reaction, cooling the reaction system to 25-30° C. and adding a neutralizer, and after a period of neutralization reaction, adding a silane coupling agent to continue the reaction, and concentrating the reaction system to obtain the polyurethane adhesive;

[0029] S3: Using a composite roller to press the kraft paper onto the polyurethane adhesive layer, and after aging, obtain the high-strength film paper material.

[0030] Furthermore, in step S2, the drying temperature is 60-90° C. and the time is 1-3 min; the heating reaction temperature is 75-85° C. and the time is 3-4 h; the neutralization reaction time is 25-30 min; and the continued reaction time is 20-30 min.

[0031] Furthermore, the heating temperature of the casting machine in step S1 is 170-180°C.

[0032] Furthermore, in step S3, the temperature of the composite roller is 65-80° C.; the aging temperature is 40-50° C., and the aging time is 60-72 hours.

[0033] Furthermore, the thickness of the polylactic acid-polybutylene terephthalate adipate plastic 1 is 18 μm; the thickness of the polyurethane adhesive 2 is 3 μm; the basis weight of the kraft paper 3 is 65 g / m 2 .

[0034] Furthermore, the corona value is ≥ 45 dynes.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention provides a high-strength film paper material, which is formed by pressing a kraft paper layer and a PLA / PBAT composite film layer using a special polyurethane adhesive. The polyurethane adhesive has excellent adhesion, which helps to improve the strength of the film paper material. The main raw materials of the polyurethane adhesive are linolenic acid-linalool and polyisocyanate. The linolenic acid-linalool structure has a quaternary ammonium salt group, an alcohol hydroxyl group, an ester group and a regular fatty chain. The quaternary ammonium salt group is introduced into the polyurethane adhesive prepared by reacting with the polyisocyanate. The quaternary ammonium salt group can enhance the interaction between polyurethane molecules, improve the viscosity of the polyurethane adhesive, and thus help to improve the peel strength of the composite film; secondly, the ester group introduced into the polyurethane adhesive has a high cohesive energy, which is also beneficial to improve its peel strength and tensile strength. In addition, the polyurethane adhesive of the present invention also has a relatively obvious antibacterial effect, thereby improving the service life of the film paper material.

[0037] (2) When preparing the polyurethane adhesive, the present invention uses a silane coupling agent to introduce a silicon-oxygen bond into the polyurethane adhesive. During the preparation of the composite film, the silicon-oxygen bond will hydrolyze into active silicon hydroxyl groups, which will undergo a condensation reaction with the active group hydroxyl groups on the surface of the substrate to form a chemical bond, thereby further improving the peel strength of the composite film.

[0038] (3) The raw materials for preparing the polyurethane adhesive of the present invention are linolenic acid and linalool, both of which can be extracted from plants. No secondary pollution will be caused during the degradation process of the film paper material, so that the composite film has both excellent mechanical properties and environmental performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the synthesis of linolenic acid-linalool of the present invention; DETAILED DESCRIPTION

[0040] Below, in conjunction with the accompanying drawings and specific embodiments, the present invention is further described. It should be noted that, under the premise of no conflict, the various embodiments described below or the various technical features can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are conventional products obtained through commercial channels.

[0041] (1) Preparation Example

[0042] Preparation Example 1

[0043] A preparation method of linolenic acid-linalool, such as Figure 1 As shown, the following steps are included:

[0044] (1) α-linolenic acid (0.2 mol), linalool (0.22 mol), and p-toluenesulfonic acid monohydrate (0.12 mmol) were added to 500 mL of toluene, stirred evenly at room temperature, and then heated to 115°C for 14 h. The reaction solution was cooled to room temperature, diluted with ethyl acetate, and poured into a saturated sodium bicarbonate aqueous solution to adjust the pH to neutral. The organic phase was separated, and the aqueous phase was extracted twice with ethyl acetate. The organic phases were combined and dried over anhydrous sodium sulfate, concentrated, and purified by distillation to obtain intermediate 1. MS: m / z (%) [M+] calcd for C 28 H 46 O2:415.35;found:415.35.

[0045] (2) Intermediate 1 (0.2 mol) was added to 700 mL of dichloromethane, cooled to 0°C, and then m-chloroperbenzoic acid (1.1 mol) was added in batches. After the addition was completed, the reaction was carried out at 5°C for 40 h. The reaction solution was naturally warmed to room temperature and 150 mL of a saturated solution of sodium thiosulfate was added to quench the reaction. After separation, the organic phase was dried over anhydrous sodium sulfate, concentrated, and purified by distillation to obtain Intermediate 2. 1 H NMR (C 28 H 46 O7, 400MHz, CDCl3): δ2.93 (m, 1H), 2.60 (m, 1H), 2.35 (m, 9H), 1.66 (m, 1H), 1.66 (m, 2H), 1.51-1.33 (m, 23H), 1.20 (s, 6H), 0.89 (t, 3H).

[0046] (3) Intermediate 2 (0.1 mol) and betaine hydrochloride (0.55 mol) were added to 500 mL of toluene, followed by tert-butyl peroxybenzoate (TBPB, 1.7 mol), and the mixture was reacted at 115°C for 6 h. The reaction solution was cooled to room temperature and quenched by adding saturated sodium bicarbonate solution. The organic phase was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent, acetonitrile:water = 70:30) to obtain linolenic acid-linalool. 1 H NMR (C 53 H 106 C l5 N5O 17 ,400MHz, CDCl3): δ5.40 (s, 3H), 4.58-4.37 (m, 6H), 4.20 (s, 10H), 4.08-3.99 (m, 4H), 3.30 (s, 45H), 2.35 (t, 2H), 1.66-1.25 (m, 27H), 1.14 (s, 6H), 0.89 (t, 3H).MS: m / z (%) [M]calcd for C53H106Cl5N5O17:1084.75; found:1084.73.

[0047] Preparation Example 2

[0048] The preparation process of the linolenic acid-linalool comprises the following steps:

[0049] (1) 0.2 mol of α-linolenic acid, 0.5 mol of linalool, and 0.13 mmol of p-toluenesulfonic acid monohydrate were added to 500 mL of toluene, stirred uniformly at room temperature, and then heated to 110° C. to react for 16 h. The reaction solution was cooled to room temperature, diluted with ethyl acetate, and poured into a saturated aqueous sodium bicarbonate solution to adjust the pH to neutral. The organic phase was separated, and the aqueous phase was extracted twice with ethyl acetate. The organic phases were combined, dried with sodium sulfate, concentrated, and purified by distillation to obtain Intermediate 1. MS results showed that they were consistent with those of Example 1.

[0050] (2) Intermediate 1 (0.2 mol) was added to 700 mL of dichloromethane, cooled to 0°C, and then (1 mol) of m-chloroperbenzoic acid was added in batches. After the addition was completed, the reaction was carried out at 0°C for 48 hours. The reaction solution was naturally warmed to room temperature and 150 mL of a saturated solution of sodium thiosulfate was added to quench the reaction. After separation, the organic phase was dried over anhydrous sodium sulfate, concentrated, and purified by distillation to obtain Intermediate 2. 1 The H NMR results were consistent with those of Example 1.

[0051] (3) Intermediate 2 (0.1 mol) and betaine hydrochloride (0.5 mol) were added to 500 mL of toluene, followed by tert-butyl peroxybenzoate (TBPB, 1.5 mol), and the mixture was reacted at 110°C for 7 h. The reaction solution was cooled to room temperature, and a saturated sodium bicarbonate solution was added to quench the reaction. The organic phase was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent, eluent, acetonitrile: water = 70:30) to obtain linolenic acid-linalool. 1 The results of H NMR and MS were consistent with those of Example 1.

[0052] Preparation Example 3

[0053] The preparation process of the linolenic acid-linalool comprises the following steps:

[0054] (1) α-linolenic acid (0.2 mol), linalool (0.30 mol), and p-toluenesulfonic acid monohydrate (0.15 mmol) were added to 500 mL of toluene, stirred evenly at room temperature, and then heated to 125°C for 12 h. The reaction solution was cooled to room temperature, diluted with ethyl acetate, and poured into a saturated sodium bicarbonate aqueous solution to adjust the pH to neutral. The organic phase was separated, and the aqueous phase was extracted twice with ethyl acetate. The organic phases were combined, dried with sodium sulfate, concentrated, and purified by distillation to obtain Intermediate 1. MS results showed that they were consistent with those of Example 1.

[0055] (2) Intermediate 1 (0.2 mol) was added to 700 mL of dichloromethane, cooled to 0°C, and then (1.2 mol) of m-chloroperbenzoic acid was added in batches. After the addition was completed, the reaction was carried out at 10°C for 36 hours. The reaction solution was naturally warmed to room temperature and 150 mL of a saturated solution of sodium thiosulfate was added to quench the reaction. After separation, the organic phase was dried over anhydrous sodium sulfate, concentrated, and purified by distillation to obtain Intermediate 2. 1 The H NMR results were consistent with those of Example 1.

[0056] (3) Intermediate 2 (0.1 mol) and betaine hydrochloride (0.6 mol) were added to 500 mL of toluene, followed by tert-butyl perbenzoate (2 mol), and the mixture was reacted at 125°C for 5 h. The reaction solution was cooled to room temperature, and a saturated sodium bicarbonate solution was added to quench the reaction. The organic phase was dried over anhydrous sodium sulfate, concentrated, and purified by column chromatography (eluent, eluent, acetonitrile: water = 70:30) to obtain linolenic acid-linalool. 1 The results of H NMR and MS were consistent with those of Example 1.

[0057] (2) Example

[0058] Example 1

[0059] A high-strength film paper material, comprising, from bottom to top, a kraft paper layer, a polyurethane adhesive layer, and a polylactic acid-polybutylene terephthalate adipate composite film layer;

[0060] The polylactic acid-polybutylene terephthalate adipate composite film layer is made of the following raw materials in parts by weight: 60 parts of polylactic acid, 40 parts of polybutylene terephthalate adipate, 1 part of titanate coupling agent, 0.3 parts of 9,10-dihydroxyoctadecanoic acid, and 0.3 parts of epoxy soybean oil;

[0061] The polyurethane adhesive layer is made of the following raw materials in parts by weight: 70 parts of linolenic acid-linalool of Preparation Example 1, 18 parts of isophorone diisocyanate, 17 parts of 2-hydroxyethyl acrylate, 3 parts of glycerol, 1.5 parts of dibutyltin dilaurate, 2.8 parts of triethylamine, and 2.8 parts of (3-glycidoxypropyl)triethoxysilane;

[0062] This embodiment also provides a method for preparing the above-mentioned high-strength membrane paper material, comprising the following steps:

[0063] S1: According to the above ratio, polylactic acid, polybutylene terephthalate adipate, titanate coupling agent, 9,10-dihydroxyoctadecanoic acid and epoxy soybean oil are mixed, melted in a twin-screw extruder (the temperatures in the temperature control zone are 40°C, 60°C, 120°C, 140°C, 150°C, 160°C, 165°C and 170°C respectively) and extruded, and then the obtained material is plasticized and granulated to obtain a polylactic acid-polybutylene terephthalate adipate blend; the polylactic acid-polybutylene terephthalate adipate blend is added to a casting machine and prepared by a casting process at 175°C to obtain the polylactic acid-polybutylene terephthalate adipate composite film layer.

[0064] S2: According to the above ratio, linolenic acid-linalool and 2-hydroxyethyl acrylate were mixed and stirred at room temperature for 0.5 h, and then isophorone diisocyanate was added in batches for reaction for 0.5 h, and then dibutyltin dilaurate was added and reacted at 78°C for 3.5 h; the reaction system was cooled to 30°C, and triethylamine was added for neutralization and reaction for 30 min. During this period, an appropriate amount of acetone was added to reduce the viscosity of the reaction system; then, the shear rate was set to 800 rpm, and deionized water was slowly added to the prepolymer. After the system phase inversion was stable, (3-glycidoxypropyl)triethoxysilane was added and reacted for 25 min. Finally, the acetone was removed using a rotary evaporator to obtain a polyurethane adhesive. The polyurethane adhesive is added to the adhesive tank, and the corona surface (corona value ≥ 45 dynes) of the polylactic acid-polybutylene terephthalate adipate composite film layer obtained in step (1) is glued and dried at 75°C for 2 minutes and 95°C for 2 minutes to form a polyurethane adhesive layer.

[0065] S3: Using a composite roller (temperature of 72° C.), press the kraft paper onto the polyurethane adhesive layer formed in step (2), and age it at 45° C. for 65 h to obtain a composite high-strength film-paper material.

[0066] Example 2

[0067] A high-strength film paper material, comprising, from bottom to top, a kraft paper layer, a polyurethane adhesive layer, and a polylactic acid-polybutylene terephthalate adipate composite film layer;

[0068] The polylactic acid-polybutylene terephthalate adipate composite film layer is made of the following raw materials in parts by weight: 50 parts of polylactic acid, 30 parts of polybutylene terephthalate adipate, 0.8 parts of titanate coupling agent, 0.2 parts of 9,10-dihydroxyoctadecanoic acid, and 0.2 parts of epoxy soybean oil;

[0069] The polyurethane adhesive layer is made of the following raw materials in parts by weight: 50 parts of linolenic acid-linalool, 15 parts of trimethyl hexamethylene diisocyanate, 11 parts of dimethylol butyric acid, 2.5 parts of glycerin, 1 part of dibutyltin dilaurate, 2.5 parts of triethylamine, and 2.5 parts of (3-glycidoxypropyl)methyldiethoxysilane;

[0070] This embodiment also provides a method for preparing the above-mentioned high-strength membrane paper material, comprising the following steps:

[0071] S1: According to the above ratio, polylactic acid, polybutylene terephthalate adipate, titanate coupling agent, 9,10-dihydroxyoctadecanoic acid and epoxy soybean oil are mixed, melted in a twin-screw extruder (the temperatures in the temperature control zone are 40°C, 60°C, 120°C, 140°C, 150°C, 160°C, 165°C and 170°C respectively) and extruded, and then the obtained material is plasticized and granulated to obtain a polylactic acid-polybutylene terephthalate adipate blend; the polylactic acid-polybutylene terephthalate adipate blend is added to a casting machine and prepared by a casting process at 170°C to obtain the polylactic acid-polybutylene terephthalate adipate composite film layer.

[0072] S2: According to the above ratio, linolenic acid-linalool and 2-hydroxyethyl acrylate were mixed and stirred at room temperature for 0.5 h, and then trimethylhexamethylene diisocyanate was added in batches to react for 0.5 h, and then dibutyltin dilaurate was added and reacted at 75°C for 4 h; the reaction system was cooled to 30°C, and triethylamine was added to neutralize the reaction for 30 min. During this period, an appropriate amount of acetone was added to reduce the viscosity of the reaction system; then, the shear rate was set to 900 rpm, and deionized water was slowly added to the prepolymer. After the system phase inversion was stable, (3-glycidoxypropyl)methyldiethoxysilane was added and reacted for 30 min. Finally, the acetone was removed using a rotary evaporator to obtain a polyurethane adhesive. The polyurethane adhesive is added to the adhesive tank, and the corona surface (corona value ≥ 45 dynes) of the polylactic acid-polybutylene terephthalate adipate composite film layer obtained in step (1) is glued and dried at 85°C for 2 minutes and 95°C for 2 minutes to form a polyurethane adhesive layer.

[0073] S3: Using a composite roller (temperature of 65° C.), press the kraft paper onto the polyurethane adhesive layer formed in step (2), and age it at 40° C. for 72 h to obtain a composite high-strength film-paper material.

[0074] Example 3

[0075] A high-strength film paper material, comprising, from bottom to top, a kraft paper layer, a polyurethane adhesive layer, and a polylactic acid-polybutylene terephthalate adipate composite film layer;

[0076] The polylactic acid-polybutylene terephthalate adipate composite film layer is made of the following raw materials in parts by weight: 70 parts of polylactic acid, 50 parts of polybutylene terephthalate adipate, 1.5 parts of titanate coupling agent, 0.5 parts of 9,10-dihydroxyoctadecanoic acid, and 0.5 parts of epoxy soybean oil;

[0077] The polyurethane adhesive layer is made of the following raw materials in parts by weight: 80 parts of linolenic acid-linalool, 20 parts of isophorone diisocyanate, 23 parts of dimethylol propionic acid, 3.5 parts of glycerin, 2 parts of dibutyltin dilaurate, 3 parts of triethylamine, and 3 parts of (3-glycidoxypropyl)triethoxysilane;

[0078] This embodiment also provides a method for preparing the above-mentioned high-strength membrane paper material, comprising the following steps:

[0079] S1: According to the above ratio, polylactic acid, polybutylene terephthalate adipate, titanate coupling agent, 9,10-dihydroxyoctadecanoic acid and epoxy soybean oil are mixed, melted in a twin-screw extruder (the temperatures in the temperature control zone are 40°C, 60°C, 120°C, 140°C, 150°C, 160°C, 165°C and 170°C respectively) and extruded, and then the obtained material is plasticized and granulated to obtain a polylactic acid-polybutylene terephthalate adipate blend; the polylactic acid-polybutylene terephthalate adipate blend is added to a casting machine and prepared by a casting process at 180°C to obtain the polylactic acid-polybutylene terephthalate adipate composite film layer.

[0080] S2: According to the above ratio, linolenic acid-linalool and 2-hydroxyethyl acrylate were mixed and stirred at room temperature for 0.5h, and then isophorone diisocyanate was added in batches to react for 0.5h, and then dibutyltin dilaurate was added and reacted at 85℃ for 3h; the reaction system was cooled to 30℃, and triethylamine was added for neutralization reaction for 30min, during which an appropriate amount of acetone was added to reduce the viscosity of the reaction system; then, the shear speed was set to 800rpm, and deionized water was slowly added to the prepolymer. After the system phase inversion was stable, (3-glycidoxypropyl) triethoxysilane was added and reacted for 20min. Finally, the acetone was removed by rotary evaporation to obtain a polyurethane adhesive. The polyurethane adhesive was added to the adhesive tank, and the corona surface (corona value ≥45 dynes) of the polylactic acid-polybutylene terephthalate adipate composite film layer obtained in step (1) was glued and dried at 65℃ for 2min and 95℃ for 2min to form a polyurethane adhesive layer.

[0081] S3: Using a composite roller (temperature of 80° C.), press the kraft paper onto the polyurethane adhesive layer formed in step (2), and age it at 50° C. for 60 h to obtain a composite high-strength film-paper material.

[0082] (3) Comparative Example

[0083] Comparative Example 1

[0084] A film paper material, which differs from Example 1 in that linolenic acid-linalool is replaced by an equal amount of polyether polyol 2000.

[0085] (IV) Test Examples

[0086] Test Example 1

[0087] The film and paper materials prepared in Examples 1 to 3 and Comparative Example 1 were subjected to peel force tests, mechanical property tests, and barrier property tests. The test methods are as follows: peel force was tested in accordance with GB / T 36392-2018 "Laminated paper and paperboard for food packaging"; tensile strength was tested in accordance with GB / T1040.3-2006 standard, with a test rate of 250 mm / min; oxygen permeability of each group of film and paper materials was measured in accordance with GB / T1038-2000 "Plastic film and sheeting - Test method for gas permeability - pressure difference method", and the test conditions were 23°C and 0% RH; water vapor permeability of each group of film and paper materials was measured in accordance with the national standard GB / T1037-88 "Plastic film and sheeting - Test method for water vapor permeability - cup method", and the test conditions were 38°C and 90% RH, as shown in Table 1.

[0088] Table 1 Performance results of the membrane paper materials of Examples 1 to 3 and Comparative Example 1

[0089]

[0090] As shown in Table 1, compared with Comparative Example 1, the film paper materials prepared in Examples 1 to 3 of the present invention have excellent peel strength and tensile properties. The main raw materials of the polyurethane adhesive of the present invention are linolenic acid-linalool and polyisocyanate. The linolenic acid-linalool structure has a quaternary ammonium salt group, an alcoholic hydroxyl group, an ester group, and a regular fatty chain. The quaternary ammonium salt group is introduced into the polyurethane adhesive prepared by reacting with the polyisocyanate. The quaternary ammonium salt group can enhance the interaction between polyurethane molecules, increase the viscosity of the polyurethane adhesive, and thus help improve the peel strength of the composite film; secondly, the ester group introduced into the polyurethane adhesive has a high cohesive energy, which is also beneficial to improve its peel strength and tensile strength.

[0091] Test Example 2

[0092] The polyurethane adhesive layers prepared in Examples 1 to 3 and Comparative Example 1 were tested for antibacterial properties. The test method was as follows: the quaternary ammonium salt aqueous polyurethane adhesive prepared above was slowly cast into a clean polytetrafluoroethylene mold, and the bubbles in the dispersion were removed in a vacuum oven. After being placed at room temperature for 1 day, the dispersion was placed in a 45°C oven for 65 hours and then cured under ultraviolet light for 30 seconds to obtain a polyurethane adhesive film sample. The antibacterial properties of the polyurethane adhesive film samples were tested according to QB / T2591-2003, as shown in Table 2.

[0093] Table 2 Antibacterial performance test results of polyurethane adhesives of Examples 1 to 3 and Comparative Example 1

[0094] category Antibacterial grade Example 1 Level 0 Example 2 Level 0 Example 3 Level 0 Comparative Example 1 >Level 2

[0095] As shown in Table 2, the polyurethane adhesive of the present invention has a significant antibacterial effect. Compared with the plastic layer and the paper base layer, the adhesive layer is more susceptible to bacterial growth, which can affect the service life of the paper-plastic composite film. The present invention improves the antibacterial properties of the adhesive, thereby extending the life of the composite film.

[0096] The above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. A high-strength film paper material, characterized in that: The high-strength film paper material comprises, from bottom to top, a kraft paper layer, a polyurethane adhesive layer, and a polylactic acid-polybutylene terephthalate adipate composite film layer; The polylactic acid-polybutylene terephthalate adipate composite film layer is made of the following raw materials in parts by weight: 50-70 parts of polylactic acid, 30-50 parts of polybutylene terephthalate adipate, 0.8-1.5 parts of titanate coupling agent, 0.2-0.5 parts of 9,10-dihydroxyoctadecanoic acid, and 0.2-0.5 parts of epoxy soybean oil; The polyurethane adhesive layer is made of the following raw materials in parts by weight: 50-80 parts of linolenic acid-linalool, 15-20 parts of polyisocyanate, 11-23 parts of hydrophilic agent, 2.5-3.5 parts of chain extender, 1-2 parts of catalyst, 2.5-3.0 parts of triethylamine, and 2.5-3.5 parts of silane coupling agent; The structure of the linolenic acid-linalool is:

2. The high-strength membrane paper material according to claim 1, characterized in that: The preparation process of the linolenic acid-linalool comprises the following steps: (1) Add α-linolenic acid, linalool, and p-toluenesulfonic acid to toluene, react at 110-125° C. for 12-16 hours, and treat to obtain intermediate 1; the structure of intermediate 1 is: (2) Add intermediate 1 to dichloromethane, cool to 0°C, then add m-chloroperbenzoic acid in batches, react at 0-10°C for 36-48 hours, and then treat to obtain intermediate 2; the structure of intermediate 2 is: (3) Add intermediate 2, betaine hydrochloride, and tert-butyl perbenzoate to toluene, react at 110-125° C. for 5-7 h, and obtain linolenic acid-linalool after treatment.

3. The high-strength membrane paper material according to claim 2, characterized in that: The molar ratio of α-linolenic acid, linalool and p-toluenesulfonic acid in step (1) is 1: (1.1-1.5): (0.6-0.75).

4. The high-strength membrane paper material according to claim 2, characterized in that: In step (2), the molar ratio of the intermediate 1 to m-chloroperbenzoic acid is 1:(5-6).

5. The high-strength membrane paper material according to claim 2, characterized in that: In step (3), the molar ratio of the intermediate 2, betaine hydrochloride, and tert-butyl perbenzoate is 1:(5-6):(15-20).

6. The high-strength membrane paper material according to claim 1, characterized in that: The polyisocyanate is one of trimethylhexamethylene diisocyanate and isophorone diisocyanate; the hydrophilic agent is one of dimethylolpropionic acid, dimethylolbutyric acid, and 2-hydroxyethyl acrylate; the chain extender is glycerol; the catalyst is dibutyltin dilaurate; and the silane coupling agent is one of (3-glycidoxypropyl)methyldiethoxysilane and (3-glycidoxypropyl)triethoxysilane.

7. The method for preparing a high-strength membrane paper material according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: adding a polylactic acid-polybutylene terephthalate adipate blend into a casting machine to prepare the polylactic acid-polybutylene terephthalate adipate composite film layer through a casting process; The preparation method of the polylactic acid-polybutylene terephthalate adipate blend comprises: mixing lactic acid, polybutylene terephthalate adipate, a titanate coupling agent, 9,10-dihydroxyoctadecanoic acid, and epoxy soybean oil, and then performing melt extrusion and granulation to obtain the blend; S2: adding polyurethane adhesive into a glue tank, applying glue on the corona surface of the polylactic acid-polybutylene terephthalate adipate composite film layer, and drying to form a polyurethane adhesive layer; The preparation method of the polyurethane adhesive comprises: mixing linolenic acid-linalool and a hydrophilic agent and stirring them uniformly, then adding a polyisocyanate and a catalyst to carry out a heating reaction, cooling the reaction system to 25-30° C. and adding a neutralizer, and after a period of neutralization reaction, adding a silane coupling agent to continue the reaction, and concentrating the reaction system to obtain the polyurethane adhesive; S3: Using a composite roller to press the kraft paper onto the polyurethane adhesive layer, and after aging, obtain the high-strength film paper material.

8. The method for preparing a high-strength membrane paper material according to claim 7, characterized in that: The drying temperature in step S2 is 60-90° C. and the time is 1-3 minutes; the heating reaction temperature is 75-85° C. and the time is 3-4 hours; the neutralization reaction time is 25-30 minutes; and the continued reaction time is 45-60 minutes.

9. The method for preparing a high-strength membrane paper material according to claim 7, characterized in that: The heating temperature of the casting machine in step S1 is 170-180°C.

10. The method for preparing a high-strength membrane paper material according to claim 7, characterized in that: In step S3, the temperature of the composite roller is 65-80° C.; the aging temperature is 40-50° C., and the aging time is 60-72 hours.

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