A bio-based solvent-free polyurethane aluminum plastic retort adhesive as well as a preparation method and application thereof

Abstract

The application provides a kind of bio-based solvent-free polyurethane aluminum plastic retort glue and its preparation method and application, the bio-based solvent-free polyurethane aluminum plastic retort glue includes component A and component B, the terminal isocyanate prepolymer obtained by the reaction of bio-based polyol A and polyisocyanate as component A, the combination of bio-based polyol B, chain extender, crosslinking agent and adhesion promoter as component B, so that the bio-based solvent-free polyurethane aluminum plastic retort glue prepared has excellent mechanical properties, higher bonding strength and excellent heat resistance, can be used in aluminum plastic retort structure, and also has the characteristics of green environmental protection, reduces carbon footprint, has good application prospect and market potential.

Description

Technical Field

[0001] This invention belongs to the field of retort technology, specifically relating to a bio-based solvent-free polyurethane aluminum-plastic retort, its preparation method, and its application. Background Technology

[0002] In flexible packaging lamination, solvent-free polyurethane adhesives are gradually becoming a new favorite in the field of flexible packaging as a substitute for solvent-based laminating adhesives. At the same time, due to the advantages of solvent-free polyurethane adhesives such as low lamination cost, fast lamination speed, energy saving, high degree of automation, safety and hygiene, they are gradually becoming the future development direction of green flexible packaging lamination.

[0003] However, the raw materials for current solvent-free polyurethane adhesives are all derived from fossil resources. With the continuous depletion of petroleum resources, finding new renewable raw materials is imperative. Bio-based raw materials have advantages over petroleum-based raw materials, such as lower cost and abundant sources. CN113105855A discloses a bio-based solvent-free two-component polyurethane-plastic composite adhesive and its preparation method. This adhesive consists of component A and component B. Component A is prepared by modifying cashew nut shell oil polyol with liquefied MDI, and component B is prepared by mixing castor oil and palm oil polyol. The ratio of component A to component B is 100:50 to 100:60. The average molecular weight of cashew nut shell oil polyol is 1000–3000, and the average molecular weight of palm oil polyol is 300–500. Furthermore, using cashew nut shell oil diol and 4,4-diphenylmethane diisocyanate (MDI), castor oil and palm oil triol as raw materials, the preparation conditions are conventional temperature, require no pressure addition, have low reaction requirements, and a high safety factor. The production process achieves zero emissions and low by-products. The resulting plastic-plastic composite adhesive has superior technical indicators compared to existing similar products. This invention is greener, lower in carbon, more environmentally friendly, and safer than existing similar products. However, this adhesive has poor heat resistance and can only be used for plastic-plastic composite structures boiled in water at 100°C.

[0004] Therefore, there is a need to develop a bio-based solvent-free polyurethane aluminum-plastic retorting adhesive with excellent heat resistance that can be used in aluminum-plastic retorting structures that can withstand 125°C. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a bio-based solvent-free polyurethane aluminum-plastic retort adhesive, its preparation method, and its application. The bio-based solvent-free polyurethane aluminum-plastic retort adhesive has high retort resistance and can be used in aluminum-plastic retort structures that can withstand 125℃. It also has green and environmentally friendly characteristics, further broadening the application range of bio-based solvent-free adhesives.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a bio-based solvent-free polyurethane aluminum-plastic retorting adhesive, wherein the bio-based solvent-free polyurethane aluminum-plastic retorting adhesive comprises component A and component B;

[0008] Component A includes a terminal isocyanate prepolymer, and the raw materials for preparing the terminal isocyanate prepolymer include bio-based polyol A and polyisocyanate.

[0009] Component B includes bio-based polyol B, chain extender, crosslinking agent, and adhesion promoter.

[0010] This invention uses a terminal isocyanate prepolymer obtained by reacting bio-based polyol A with polyisocyanate as component A, and a combination of bio-based polyol B, chain extender, crosslinking agent and adhesion promoter as component B. By selecting the above specific components A and B, the prepared bio-based solvent-free polyurethane aluminum-plastic retorting adhesive has excellent mechanical properties, bonding strength and excellent heat resistance. It can be used in aluminum-plastic retorting structures that can withstand 125℃ for 30 minutes. At the same time, it has green and environmentally friendly characteristics, reduces carbon footprint, and has good application prospects and market potential.

[0011] Preferably, the raw materials for preparing the terminal isocyanate prepolymer include, by weight, 40-45 parts of bio-based polyol A and 55-60 parts of polyisocyanate.

[0012] The amount of bio-based polyol A added can be 40.5 parts by weight, 41 parts by weight, 41.5 parts by weight, 42 parts by weight, 42.5 parts by weight, 43 parts by weight, 43.5 parts by weight, 44 parts by weight, or 44.5 parts by weight, etc.

[0013] The polyisocyanate may be in quantities of 55.5 parts by weight, 56 parts by weight, 56.5 parts by weight, 57 parts by weight, 57.5 parts by weight, 58 parts by weight, 58.5 parts by weight, 59 parts by weight, or 59.5 parts by weight, etc.

[0014] Preferably, component B comprises the following components in parts by weight:

[0015]

[0016] The bio-based polyol B can be 91 parts by weight, 92 parts by weight, 93 parts by weight, 94 parts by weight, 95 parts by weight, or 96 parts by weight, etc.

[0017] The chain extender can be 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, or 4.5 parts by weight, etc.

[0018] The crosslinking agent can be 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, or 4.5 parts by weight, etc.

[0019] The adhesion promoter can be 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, or 0.45 parts by weight, etc.

[0020] Preferably, the polyisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), or isophorone diisocyanate (IPDI).

[0021] Preferably, both bio-based polyol A and bio-based polyol B include polypropylene carbonate polyol.

[0022] Preferably, the number average molecular weight of the bio-based polypropylene carbonate polyol is 500 to 3000, such as 1000, 1500, 2000 or 2500.

[0023] Preferably, the mass percentage of polycarbonate groups in the bio-based polypropylene carbonate polyol is 5% to 45%, such as 10%, 15%, 20%, 25%, 30%, 35%, or 40%.

[0024] Preferably, the bio-based polyol A and bio-based polyol B further include other bio-based polyester polyols besides bio-based polypropylene carbonate polyols, and the raw materials for preparing the other bio-based polyester polyols include bio-based acids and bio-based alcohols.

[0025] Preferably, the bio-based acid includes any one or a combination of at least two of bio-based succinic acid, bio-based sebacic acid, bio-based polylactic acid, or bio-based furanyl dicarboxylic acid.

[0026] Preferably, the bio-based alcohol comprises any one or a combination of at least two of bio-based 1,3-propanediol, bio-based 1,2-propanediol, bio-based ethylene glycol, bio-based 1,4-butanediol, or bio-based isosorbide.

[0027] Preferably, the number average molecular weight of the other bio-based polyester polyols is 500 to 3000, such as 1000, 1500, 2000 or 2500, and more preferably 500 to 2000.

[0028] Preferably, the bio-based polyol A includes other bio-based polyester polyols and bio-based polypropylene carbonate polyols in a mass ratio of (1-5):(5-1) (e.g., 2:5, 3:5, 4:5, 5:2, 5:3, or 5:4, etc.).

[0029] Preferably, the bio-based polyol B includes other bio-based polyester polyols and bio-based polypropylene carbonate polyols in a mass ratio of (2-6):1 (e.g., 2.5:1, 3:1, 3.5:1, 4:1 or 4.5:1, etc.).

[0030] As a preferred technical solution of the present invention, the bio-based polyol A is defined to include other bio-based polyester polyols and bio-based polypropylene carbonate polyols, and the bio-based polyol B is defined to include other bio-based polyester polyols and bio-based polypropylene carbonate polyols in combination. The advantage of this combination is that the specific bio-based polyester polyols selected in the present invention have good heat resistance, and the bio-based polypropylene carbonate has good ink compatibility and will not cause ink dissolution. The combination of the two can achieve the best overall performance.

[0031] Preferably, the chain extender comprises any one or a combination of at least two of ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol (BD), neopentyl glycol, 1,6-hexanediol (HD), glycerol, diethylene glycol (DEG), diethanolamine, dihydroxyethylaniline, or diaminodicyclohexylmethane.

[0032] Preferably, the crosslinking agent comprises any one or a combination of at least two of trimethylolpropane, glycerol, or triethanolamine.

[0033] Preferably, the adhesion promoter comprises any one or a combination of at least two of vinyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-glycidoxypropyltriethoxysilane.

[0034] Preferably, the molar ratio of component A to component B is (1.5 to 2.5):1, such as 1.7:1, 1.9:1, 2.1:1 or 2.3:1.

[0035] In a second aspect, the present invention provides a method for preparing a bio-based solvent-free polyurethane aluminum-plastic retort as described in the first aspect, the method comprising the following steps:

[0036] (1) React bio-based polyol A with polyisocyanate to obtain component A;

[0037] Component B is obtained by mixing bio-based polyol B, chain extender, crosslinking agent and adhesion promoter;

[0038] (2) Mix component A and component B to obtain the bio-based solvent-free polyurethane aluminum-plastic retort.

[0039] Preferably, the reaction temperature in step (1) is 70 to 90°C, for example, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C or 88°C.

[0040] Preferably, the reaction time in step (1) is 2 to 4 hours, such as 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, 3.2 hours, 3.4 hours, 3.6 hours or 3.8 hours.

[0041] Preferably, the reaction in step (1) is carried out under nitrogen protection.

[0042] Preferably, the mixing temperature in step (1) is 30 to 60°C, such as 35°C, 40°C, 45°C, 50°C or 55°C.

[0043] Preferably, the mixing time in step (1) is 1 to 4 hours, such as 1.5 hours, 2 hours, 2.5 hours, 3 hours or 3.5 hours.

[0044] Thirdly, the present invention provides an application of the bio-based solvent-free polyurethane aluminum-plastic retort as described in the first aspect in the bonding of flexible packaging composite materials.

[0045] Preferably, the flexible packaging composite material includes CPP, BOPP, PA, PET, PE, aluminum foil, or aluminized film.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The bio-based solvent-free polyurethane aluminum-plastic retort apparatus provided by this invention has advantages such as excellent mechanical properties, high bonding strength and excellent heat resistance. It can be used in aluminum-plastic retort apparatus structures that can withstand 125℃ for 30 minutes. At the same time, this bio-based solvent-free polyurethane aluminum-plastic retort apparatus is more green and environmentally friendly, reduces carbon footprint, and has good application prospects and market potential. Detailed Implementation

[0048] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0049] The following is some information about the raw materials involved in the specific embodiments of this invention:

[0050] Bio-based polypropylene sebacic acid polyol: hydroxyl value is 112 mg KOH / g, number average molecular weight is 1000, and its raw materials include bio-based sebacic acid and bio-based 1,2-propanediol;

[0051] Bio-based polypropylene furanate polyol: hydroxyl value is 112 mg KOH / g, number average molecular weight is 1000, and its raw materials include bio-based furanate and bio-based propylene glycol.

[0052] Bio-based polypropylene sebacic acid isosorbide ester polyol: hydroxyl value is 56 mg KOH / g, number average molecular weight is 2000, and its raw materials include bio-based sebacic acid and bio-based isosorbide;

[0053] Bio-based polypropylene carbonate polyol PPC-2202P: hydroxyl value is 56 mg KOH / g, number average molecular weight is 2000, and the mass percentage of polycarbonate groups is 30%.

[0054] Bio-based polypropylene carbonate polyol PPC-3202H: hydroxyl value of 40 mg KOH / g, number average molecular weight of 2800, and polycarbonate group mass percentage of 30%;

[0055] MDI-50 polyisocyanate: purchased from Wanhua Chemical;

[0056] Diethylene glycol: Mn = 106;

[0057] Adhesion promoters: γ-glycidoxypropyltrimethoxysilane (KH560), purchased from Chenguang Chemical; vinyltrimethoxysilane (A-171), purchased from Momentive Chemical.

[0058] Example 1

[0059] A bio-based solvent-free polyurethane aluminum-plastic retort comprises component A and component B in a molar ratio of 1.8:1;

[0060] Component A is a terminal isocyanate prepolymer, and the raw materials for its preparation include the following components by weight:

[0061] 30 parts by weight of bio-based polypropylene sebacate polyol

[0062] Bio-based polypropylene carbonate polyol PPC-2202P 15 parts by weight

[0063] 55 parts by weight of polyisocyanate MDI-50;

[0064] Component B comprises the following components by weight:

[0065]

[0066] The preparation method of the bio-based solvent-free polyurethane aluminum-plastic retort provided in this embodiment includes the following steps:

[0067] (1) Bio-based polypropylene sebacate polyol, bio-based polypropylene carbonate polyol PPC-2202P and polyisocyanate MDI-50 were reacted at 70℃ for 4h to obtain component A.

[0068] Component B is obtained by mixing bio-based polypropylene sebacate polyol, bio-based polypropylene carbonate polyol PPC-2202P, diethylene glycol, triethanolamine and adhesion promoter KH560.

[0069] (2) Mix component A and component B to obtain the bio-based solvent-free polyurethane aluminum-plastic retort.

[0070] Example 2

[0071] A bio-based solvent-free polyurethane aluminum-plastic retort comprises component A and component B in a molar ratio of 2:1;

[0072] Component A is a terminal isocyanate prepolymer, and the raw materials for its preparation include the following components by weight:

[0073] 30 parts by weight of bio-based polypropylene sebacate polyol

[0074] Bio-based polypropylene carbonate polyol PPC-2202P 15 parts by weight

[0075] 55 parts by weight of polyisocyanate MDI-50;

[0076] Component B comprises the following components by weight:

[0077]

[0078] The preparation method of the bio-based solvent-free polyurethane aluminum-plastic retort provided in this embodiment includes the following steps:

[0079] (1) Bio-based polypropylene sebacate polyol, bio-based polypropylene carbonate polyol PPC-2202P and polyisocyanate MDI-50 were reacted at 70℃ for 4h to obtain component A.

[0080] Component B is obtained by mixing bio-based polypropylene glycol difuranate polyol, bio-based polypropylene carbonate polyol PPC-2202P, diethylene glycol, triethanolamine and adhesion promoter KH560.

[0081] (2) Mix component A and component B to obtain the bio-based solvent-free polyurethane aluminum-plastic retort.

[0082] Example 3

[0083] A bio-based solvent-free polyurethane aluminum-plastic retort comprises component A and component B in a molar ratio of 1.75:1;

[0084] Component A is a terminal isocyanate prepolymer, and the raw materials for its preparation include the following components by weight:

[0085] 30 parts by weight of bio-based polypropylene sebacate polyol

[0086] Bio-based polypropylene carbonate polyol PPC-2202P 15 parts by weight

[0087] 55 parts by weight of polyisocyanate MDI-50;

[0088] Component B comprises the following components by weight:

[0089]

[0090] The preparation method of the bio-based solvent-free polyurethane aluminum-plastic retort provided in this embodiment includes the following steps:

[0091] (1) Bio-based polypropylene sebacate polyol, bio-based polypropylene carbonate polyol PPC-2202P and polyisocyanate MDI-50 were reacted at 70℃ for 4h to obtain component A.

[0092] Component B is obtained by mixing bio-based polypropylene sebacate isosorbide ester polyol, bio-based polypropylene carbonate polyol PPC-3202H, diethylene glycol, triethanolamine and adhesion promoter A-171.

[0093] (2) Mix component A and component B to obtain the bio-based solvent-free polyurethane aluminum-plastic retort.

[0094] Example 4

[0095] A bio-based solvent-free polyurethane aluminum-plastic retort comprises component A and component B in a molar ratio of 1.9:1;

[0096] Component A is a terminal isocyanate prepolymer, and the raw materials for its preparation include the following components by weight:

[0097] 10 parts by weight of bio-based polypropylene glycol difuranate polyol

[0098] Bio-based polypropylene carbonate polyol PPC-3202H 30 parts by weight

[0099] 60 parts by weight of polyisocyanate MDI-50;

[0100] Component B comprises the following components by weight:

[0101]

[0102] The preparation method of the bio-based solvent-free polyurethane aluminum-plastic retort provided in this embodiment includes the following steps:

[0103] (1) Bio-based polypropylene glycol furanate polyol, bio-based polypropylene carbonate polyol PPC-3202H and polyisocyanate MDI-50 were reacted at 75℃ for 3h to obtain component A.

[0104] Component B is obtained by mixing bio-based polypropylene sebacate polyol, bio-based polypropylene carbonate polyol PPC-2202P, diethylene glycol, triethanolamine and adhesion promoter KH560.

[0105] (2) Mix component A and component B to obtain the bio-based solvent-free polyurethane aluminum-plastic retort.

[0106] Example 5

[0107] A bio-based solvent-free polyurethane aluminum-plastic retort comprises component A and component B in a molar ratio of 1.8:1;

[0108] Component A is a terminal isocyanate prepolymer, and the raw materials for its preparation include the following components by weight:

[0109] 10 parts by weight of bio-based polypropylene glycol difuranate polyol

[0110] Bio-based polypropylene carbonate polyol PPC-3202H 30 parts by weight

[0111] 60 parts by weight of polyisocyanate MDI-50;

[0112] Component B comprises the following components by weight:

[0113]

[0114] The preparation method of the bio-based solvent-free polyurethane aluminum-plastic retort provided in this embodiment includes the following steps:

[0115] (1) Bio-based polypropylene glycol furanate polyol, bio-based polypropylene carbonate polyol PPC-3202H and polyisocyanate MDI-50 were reacted at 75℃ for 3h to obtain component A.

[0116] Component B is obtained by mixing bio-based polypropylene glycol difuranate polyol, bio-based polypropylene carbonate polyol PPC-2202P, diethylene glycol, triethanolamine and adhesion promoter KH560.

[0117] (2) Mix component A and component B to obtain the bio-based solvent-free polyurethane aluminum-plastic retort.

[0118] Example 6

[0119] A bio-based solvent-free polyurethane aluminum-plastic retort comprises component A and component B in a molar ratio of 1.8:1;

[0120] Component A is a terminal isocyanate prepolymer, and the raw materials for its preparation include the following components by weight:

[0121] 10 parts by weight of bio-based polypropylene glycol difuranate polyol

[0122] Bio-based polypropylene carbonate polyol PPC-3202H 30 parts by weight

[0123] 60 parts by weight of polyisocyanate MDI-50;

[0124] Component B comprises the following components by weight:

[0125]

[0126] The preparation method of the bio-based solvent-free polyurethane aluminum-plastic retort provided in this embodiment includes the following steps:

[0127] (1) Bio-based polypropylene glycol furanate polyol, bio-based polypropylene carbonate polyol PPC-3202H and polyisocyanate MDI-50 were reacted at 75℃ for 3h to obtain component A.

[0128] Component B is obtained by mixing bio-based polypropylene sebacate isosorbide ester polyol, bio-based polypropylene carbonate polyol PPC-3202H, diethylene glycol, triethanolamine and adhesion promoter A-171.

[0129] (2) Mix component A and component B to obtain the bio-based solvent-free polyurethane aluminum-plastic retort.

[0130] Example 7

[0131] A bio-based solvent-free polyurethane aluminum-plastic retort comprises component A and component B in a molar ratio of 1.8:1;

[0132] Component A is a terminal isocyanate prepolymer, and the raw materials for its preparation include the following components by weight:

[0133] 35 parts by weight of bio-based polypropylene sebacate isosorbide polyol

[0134] Bio-based polypropylene carbonate polyol PPC-2202P 10 parts by weight

[0135] 55 parts by weight of polyisocyanate MDI-50;

[0136] Component B comprises the following components by weight:

[0137]

[0138] The preparation method of the bio-based solvent-free polyurethane aluminum-plastic retort provided in this embodiment includes the following steps:

[0139] (1) Bio-based polypropylene sebacate isosorbide polyol, bio-based polypropylene carbonate polyol PPC-2202P and polyisocyanate MDI-50 were reacted at 90℃ for 2h to obtain component A.

[0140] Component B is obtained by mixing bio-based polypropylene sebacate isosorbide ester polyol, bio-based polypropylene carbonate polyol PPC-3202H, diethylene glycol, triethanolamine and adhesion promoter A-171.

[0141] (2) Mix component A and component B to obtain the bio-based solvent-free polyurethane aluminum-plastic retort.

[0142] Example 8

[0143] A bio-based solvent-free polyurethane aluminum-plastic retort differs from Example 1 only in that bio-based polypropylene sebacate polyol is not added to component A, and the amount of bio-based polypropylene carbonate polyol PPC-2202P added is 45 parts by weight. Other components, dosages, and preparation methods are the same as in Example 1.

[0144] Example 9

[0145] A bio-based solvent-free polyurethane aluminum-plastic retort differs from Example 1 only in that bio-based polypropylene carbonate polyol PPC-2202P is not added to component A, and the amount of bio-based polypropylene sebacate polyol added is 45 parts by weight. Other components, amounts, and preparation methods are the same as in Example 1.

[0146] Example 10

[0147] A bio-based solvent-free polyurethane aluminum-plastic retort differs from Example 1 only in that bio-based polypropylene sebacate polyol is not added to component B, and the amount of bio-based polypropylene carbonate polyol PPC-2202P added is 90 parts by weight. Other components, dosages, and preparation methods are the same as in Example 1.

[0148] Example 11

[0149] A bio-based solvent-free polyurethane aluminum-plastic retort differs from Example 1 only in that bio-based polypropylene carbonate polyol PPC-2202P is not added to component B, and the amount of bio-based polypropylene sebacate polyol added is 90 parts by weight. Other components, dosages, and preparation methods are the same as in Example 1.

[0150] Comparative Example 1

[0151] A bio-based solvent-free polyurethane aluminum-plastic retort differs from Example 1 only in that ordinary polyester polyol (Huafeng, PE-33) is used to replace the bio-based polypropylene sebacate polyol in components A and B. The other components, dosages, and preparation methods are the same as in Example 1.

[0152] Comparative Example 2

[0153] A bio-based solvent-free polyurethane aluminum-plastic retort differs from Example 1 only in that a common polyether polyol (Jiahua Chemical, D220) is used to replace the bio-based polypropylene carbonate polyol PPC-2202P in components A and B. The other components, dosages, and preparation methods are the same as in Example 1.

[0154] Performance testing:

[0155] (1) Peel strength: Bio-based solvent-free polyurethane aluminum-plastic retort was used to laminate PET / AL / RCPP structures at 50°C using a solvent-free laminating machine, with an adhesive application rate of 1.8–2.0 g / m³. 2 The T-type peel strength was measured after aging in an oven at 50℃ for 50 hours and after steaming at 125℃ for 30 minutes. The test speed was 300 mm / min.

[0156] (2) Compatibility of adhesive and ink: Apply ink to PET film with a scraper, dry it with a hair dryer and set aside. Apply the adhesive to be evaluated to ink with a scraper, cover it with an aluminized PET film, press it with a roller, place the coated sample in a 50℃ oven and cure it for 1 day. After taking it out, observe whether the aluminized PET film is dissolved by the ink. If it does not dissolve, the compatibility is good. If it dissolves completely, the compatibility is poor. If it is between the two, the compatibility is moderate.

[0157] The tests were conducted on Examples 1-11 and Comparative Examples 1-2 according to the above test plan, and the test results are shown in Table 1:

[0158] Table 1

[0159]

[0160] According to the data in Table 1:

[0161] The bio-based solvent-free polyurethane aluminum-plastic retorts obtained in Examples 1-7, after curing at 50°C, showed no peel strength against PET / AL, with the PET film breaking, indicating excellent adhesion. The peel strength against AL / RCPP was as high as 6.2-7.7 N / 15 mm. After retorting at 125°C, the peel strength test for PET / AL still showed no peel strength, with the PET film breaking, while the peel strength against AL / RCPP was as high as 5.2-6.1 N / 15 mm, indicating good heat resistance and good compatibility with inks.

[0162] Comparing the data from Examples 1, 8-11 and Comparative Examples 1-2, it can be seen that using bio-based polyester polyol alone, using bio-based polypropylene carbonate polyol alone, or using ordinary polyether polyol or ordinary polyester polyol will all lead to defects in certain aspects of the prepared bio-based solvent-free polyurethane aluminum-plastic retort.

[0163] In summary, the present invention utilizes both bio-based polyester polyols and bio-based polypropylene carbonate polyols to produce solvent-free polyurethane aluminum-plastic retorts with good ink compatibility and heat resistance.

[0164] The applicant declares that this invention illustrates the bio-based solvent-free polyurethane aluminum-plastic retort adhesive, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A bio-based solvent-free polyurethane aluminum-plastic retort, characterized in that, The bio-based solvent-free polyurethane aluminum-plastic retort comprises component A and component B; Component A includes a terminal isocyanate prepolymer, and the raw materials for preparing the terminal isocyanate prepolymer include, by weight, 40-45 parts of bio-based polyol A and 55-60 parts of polyisocyanate. The bio-based polyol A includes other bio-based polyester polyols and bio-based polypropylene carbonate polyols in a mass ratio of (1~5):(5~1); Component B comprises the following components in parts by weight: Bio-based polyol B 90~97 parts by weight 1-5 parts by weight of chain extender 1-5 parts by weight of crosslinking agent 1 part by weight or 1.5 parts by weight of adhesion promoter; The bio-based polyol B includes other bio-based polyester polyols and bio-based polypropylene carbonate polyols in a mass ratio of (2~6):1; In the bio-based polyols A and B, the raw materials for preparing the other bio-based polyester polyols include bio-based acids and bio-based alcohols. The bio-based acid is selected from any one or a combination of at least two of the following: bio-based succinic acid, bio-based sebacic acid, bio-based polylactic acid, or bio-based furanyl dicarboxylic acid. The bio-based alcohol is selected from any one or a combination of at least two of the following: bio-based 1,3-propanediol, bio-based 1,2-propanediol, bio-based ethylene glycol, bio-based 1,4-butanediol, or bio-based isosorbide. The molar ratio of component A to component B is (1.5~2.5):

1.

2. The bio-based solvent-free polyurethane aluminum-plastic retort according to claim 1, characterized in that, The polyisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, or isophorone diisocyanate.

3. The bio-based solvent-free polyurethane aluminum-plastic retort according to claim 1, characterized in that, The number-average molecular weight of the bio-based polypropylene carbonate polyol is 500-3000.

4. The bio-based solvent-free polyurethane aluminum-plastic retort according to claim 1, characterized in that, The bio-based polypropylene carbonate polyol has a polycarbonate group content of 5-45% by mass.

5. The bio-based solvent-free polyurethane aluminum-plastic retort according to claim 1, characterized in that, The number average molecular weight of the other bio-based polyester polyols is 500-3000.

6. The bio-based solvent-free polyurethane aluminum-plastic retort according to claim 1, characterized in that, The chain extender includes any one or a combination of at least two of the following: ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, glycerol, diethylene glycol, diethanolamine, dihydroxyethylaniline, or diaminodicyclohexylmethane.

7. The bio-based solvent-free polyurethane aluminum-plastic retort according to claim 1, characterized in that, The crosslinking agent includes any one or a combination of at least two of trimethylolpropane, glycerol, or triethanolamine.

8. The bio-based solvent-free polyurethane aluminum-plastic retort according to claim 1, characterized in that, The adhesion promoter includes any one or a combination of at least two of vinyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, or γ-glycidoxypropyltriethoxysilane.

9. A method for preparing a bio-based solvent-free polyurethane aluminum-plastic retort as described in any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: (1) React bio-based polyol A with polyisocyanate to obtain component A; Component B is obtained by mixing bio-based polyol B, chain extender, crosslinking agent and adhesion promoter; (2) Mix component A and component B to obtain the bio-based solvent-free polyurethane aluminum-plastic retort.

10. The preparation method according to claim 9, characterized in that, The reaction temperature in step (1) is 70~90℃.

11. The preparation method according to claim 9, characterized in that, The reaction time in step (1) is 2 to 4 hours.

12. The preparation method according to claim 9, characterized in that, The reaction described in step (1) is carried out under nitrogen protection.

13. The preparation method according to claim 9, characterized in that, The mixing temperature in step (1) is 30~60℃.

14. The preparation method according to claim 9, characterized in that, The mixing time in step (1) is 1 to 4 hours.

15. The application of a bio-based solvent-free polyurethane aluminum-plastic retort as described in any one of claims 1 to 8 in the bonding of flexible packaging composite materials.

16. The application according to claim 15, characterized in that, The flexible packaging composite materials include CPP, BOPP, PA, PET, PE, aluminum foil, or aluminized film.

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