Reactive polyurethane hot melt adhesive for laminating and compounding low-surface-energy material and preparation method of reactive polyurethane hot melt adhesive

Abstract

The invention provides a reactive polyurethane hot melt adhesive for laminating and compounding a low-surface-energy material and a preparation method of the reactive polyurethane hot melt adhesive, and relates to the technical field of polyurethane hot melt adhesives. Polyhydroxyl groups of the alkyl glycoside enable the alkyl glycoside to have good compatibility with polyether polyol and polyester polyol, and the polyhydroxyl groups react with isocyanate to form a certain degree of crosslinking, so that polyurethane molecules have higher cohesion strength; meanwhile, a long alkyl chain of alkyl glycoside is suspended beside a polyurethane main chain, and the polarity of the long alkyl chain is very low, so that the long alkyl chain has very good wettability on a low-surface-energy base material. Therefore, the polyurethane hot melt adhesive prepared by the invention can effectively infiltrate a base material in the actual use curing process of lamination and compounding of a low-surface-energy material, the bonding strength is not influenced by the low surface energy of the base material, and the polyurethane hot melt adhesive has relatively high initial bonding strength and relatively high final bonding strength.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane hot melt adhesives, and in particular relates to a reactive polyurethane hot melt adhesive for laminating and compounding low surface energy materials and a preparation method thereof. Background Art

[0002] As the degree of global industrialization continues to deepen, environmental problems are becoming increasingly prominent; solvent-based adhesives commonly used in the manufacturing industry are a common source of volatile pollutants, so their environmentally friendly alternative - hot melt adhesives - has received increasing attention in recent years.

[0003] Hot melt polyurethane reactive adhesive (hereinafter referred to as HMPUR) is usually composed of polyurethane prepolymers with isocyanate as the terminal group. This adhesive is generally made by reacting polyols and excess isocyanate. It is usually solid at room temperature and softens to liquid when heated. After application, it can be quickly cooled to form a high initial bonding strength, and then the isocyanate reacts with the moisture in the environment or the substrate to form the final bonding strength. Due to the diversity of HMPUR raw materials, different types of substrates can be bonded, such as metals, plastics, glass and ceramics.

[0004] Among them, low surface energy materials (such as PE\PP\POE\PVC with high plasticizer content, etc.) are also common laminated substrates. Such substrates are widely used in the fields of automobiles, new energy, consumer electronics, textiles and clothing, and packaging. However, due to their low surface energy, the surface of such materials is difficult to be wetted, and many adhesives are difficult to achieve good bonding effects.

[0005] At present, the industry often uses solvent adhesives with solvent as the main component to achieve wetting and achieve better bonding effect; however, solvent adhesives contain volatile organic solvents, have poor environmental performance, and may cause pollution to the environment during use. Hot melt adhesives are non-toxic and odorless, and are environmentally friendly chemical products; however, due to the high surface energy of hot melt adhesive melt, the interface is not well wetted and the adhesion is insufficient, which ultimately results in a decrease in the overall bonding strength, affecting the application effect in the field. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention proposes a reactive polyurethane hot melt adhesive for laminating and compounding low surface energy materials and a preparation method thereof, the purpose of which is to introduce an alkyl glycoside with a carbon chain length of ≥6 into a single-component moisture-curing polyurethane hot melt adhesive system, so that the alkyl glycoside has good compatibility with polyether polyols and polyester polyols, and the polyhydroxyl groups of the alkyl glycoside react with isocyanate to improve the crosslinking degree of the system itself, so that the polyurethane molecules have a higher cohesive strength; at the same time, the long alkyl chain with very low polarity in the alkyl glycoside is suspended next to the polyurethane main chain, and has good wettability to low surface energy substrates, greatly improving the bonding strength of the hot melt adhesive product. The problem that the surface energy of the existing hot melt adhesive melt is high, resulting in poor interface wetting and insufficient adhesion is solved.

[0007] The components of a reactive polyurethane hot melt adhesive for laminating and compounding low surface energy materials of the present invention include: alkyl polyglycoside, polyether polyol, amorphous polyester polyol, liquid polyester polyol, tackifying resin, isocyanate as main ingredients, and stabilizer, antioxidant and catalyst as auxiliary ingredients; wherein the mass fractions of each component are: 1-5 parts of alkyl polyglycoside, 10-30 parts of polyether polyol, 10-20 parts of amorphous polyester polyol, 10-20 parts of liquid polyester polyol, 0-20 parts of tackifying resin, 20-30 parts of isocyanate, 0.01-0.1 parts of stabilizer, 0.1-0.5 parts of antioxidant, and 0.1-0.3 parts of catalyst;

[0008] The alkyl glucoside is one of hexyl glucoside, octyl glucoside, decyl glucoside and dodecyl glucoside, and the carbon chain length is ≥6;

[0009] The amorphous polyester polyol is an aromatic polyester polyol; its glass transition temperature is greater than 15°C, and its hydroxyl value is 30mgKOH / g-120mgKOH / g;

[0010] The liquid polyester polyol is an aromatic polyester polyol or an aliphatic polyester polyol; its glass transition temperature is less than -25°C, and its hydroxyl value is 18 mgKOH / g-34 mgKOH / g.

[0011] Preferably, the polyether polyol is one of polyoxypropylene glycol, polyoxyethylene glycol, polyoxypropylene-ethylene glycol, polyoxypropylene triol, and polytetramethylene ether glycol, and its hydroxyl value is 18 mgKOH / g-120 mgKOH / g;

[0012] Preferably, the polyacid of the amorphous polyester polyol is selected from one or more of terephthalic acid, phthalic anhydride, and isophthalic acid; the polyol is selected from one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 1,4-cyclohexanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol;

[0013] Preferably, the polyacid of the liquid polyester polyol is selected from one or more of terephthalic acid, phthalic anhydride, isophthalic acid, adipic acid, and sebacic acid; the polyol is selected from one or more of diethylene glycol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 1,4-cyclohexanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol;

[0014] Preferably, the tackifying resin is selected from one or more of acrylic resin, petroleum resin, rosin resin and terpene resin;

[0015] Preferably, the isocyanate is one of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, isophorone diisocyanate toluene diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate;

[0016] Preferably, the stabilizer is one of phosphoric acid, polyphosphoric acid, p-toluenesulfonyl isocyanate, sebacic acid, benzoyl chloride, and azelaic acid;

[0017] Preferably, the antioxidant is one of antioxidant 1010, antioxidant 168, antioxidant 1035, antioxidant 1076, antioxidant 1135, antioxidant 5057, and triphenyl phosphite;

[0018] Preferably, the catalyst is one of dibutyltin dilaurate, stannous octoate, tetrabutyl titanate, triethylenediamine, 1,4-dimethylpiperazine, bismorpholinyl diethyl ether, bismorpholinyl triethyl ether, and dimorpholine polyoxyethylene ether.

[0019] The present invention also provides a method for preparing a reactive polyurethane hot melt adhesive for laminating low surface energy materials, comprising the following steps:

[0020] (1) Put the stabilizer, antioxidant and tackifying resin into a vacuum reactor, heat it to 130° C.-140° C., mix and stir to melt for 1 h-2 h;

[0021] (2) adding alkyl polyglycoside, polyether polyol, amorphous polyester polyol and liquid polyester polyol, stirring and melting at 130° C.-140° C., and dehydrating under vacuum ≤-0.098 MPa for 1 h-2 h, wherein the water content after dehydration is ≤500 ppm;

[0022] (3) Cooling to 95°C-105°C, adding isocyanate, mixing and stirring evenly, heating to 115°C-125°C, and reacting for 1h-1.5h;

[0023] (4) adding a catalyst and performing a vacuum degassing reaction at 115° C. to 125° C. for 0.5 h to 1 h;

[0024] (5) After discharging, sealing and packaging, the reactive polyurethane hot melt adhesive is obtained.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention introduces an alkyl glycoside with a carbon chain length of ≥6 into a reactive polyurethane hot melt adhesive system, and improves the adhesion to a low surface energy substrate by designing a specific ratio of the alkyl glycoside in the main material (a too high addition ratio will cause the reaction system to gel easily, and a too low addition ratio will cause the product to have a poor bonding effect on a low surface energy substrate). Alkyl glycoside is a biodegradable polyhydroxy compound, and has a long alkyl chain with an affinity low polarity structure; wherein the polyhydroxy group makes the alkyl glycoside have good compatibility with polyether polyols and polyester polyols, and the polyhydroxy group reacts with isocyanate to form a certain degree of crosslinking, so that the polyurethane molecule has a higher cohesive strength; at the same time, the long alkyl chain of the alkyl glycoside is suspended next to the polyurethane main chain, and the polarity of the long alkyl chain is very low, and it has good wettability to the low surface energy substrate.

[0027] Therefore, the polyurethane hot melt adhesive prepared by the present invention can effectively achieve the infiltration of the substrate during the actual curing process of laminating and compounding low surface energy materials, and the bonding strength will not be affected by the low surface energy of the substrate, and has both high initial bonding strength and high final bonding strength. At the same time, the preparation method provided by the present invention is simple, easy to control, mild conditions, and suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The schematic diagram is a structural formula of the reaction between the polyhydroxyl groups of the alkyl polyglycoside of the present invention and isocyanate. DETAILED DESCRIPTION

[0029] In order to better understand the content of the present invention, the present invention will be further described below in conjunction with specific examples. The following examples are based on the technology of the present invention and provide detailed implementation methods and operating steps, but the protection scope of the present invention is not limited to the following examples, that is, based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0030] Meanwhile, in each embodiment of the present invention, there is no special restriction on the source of each material, and commercially available products known to those skilled in the art and meeting the relevant property requirements may be used.

[0031] Example 1

[0032] Table 1: Composition and mass ratio of raw materials used in Example 1

[0033]

[0034]

[0035] Table 1 shows the raw material composition and mass fraction ratio of the reactive polyurethane hot melt adhesive for laminating low surface energy materials prepared in this embodiment; the specific preparation method is as follows:

[0036] (1) Add stabilizer, antioxidant and tackifying resin into a vacuum reactor, heat to 140° C., mix and stir to melt for 1 h;

[0037] (2) adding alkyl polyglycoside, polyether polyol, amorphous polyester polyol and liquid polyester polyol, stirring and melting at 140° C., and dehydrating under vacuum conditions of ≤-0.098 MPa for 1 h, wherein the water content after dehydration is ≤500 ppm;

[0038] (3) Cooling to 100°C, then adding isocyanate, stirring and mixing evenly, heating to 120°C, and reacting for 1 hour;

[0039] (4) adding a catalyst and performing a vacuum degassing reaction at 120° C. for 0.5 h (viscosity and NCO% reach the preset targets);

[0040] (5) After discharging, sealing and packaging, the reactive polyurethane hot melt adhesive is obtained.

[0041] Example 2

[0042] Compared with Example 1, the raw material composition and mass fraction ratio of this example are shown in Table 2;

[0043] Table 2: Composition and mass fraction ratio of raw materials used in Example 2

[0044] Raw material type raw material Mass fraction Alkyl glycoside Octyl Glucoside 5 Polyether polyols Polyoxyethylene glycol 10 Amorphous polyester polyol HDPOL-320P 20 Liquid polyester polyol HDPOL-322 20 Tackifying resin Petroleum resin 20 Isocyanate Hexamethylene diisocyanate 25 Stabilizer p-Toluenesulfonyl isocyanate 0.01 Antioxidants 1035 0.2 catalyst Tetrabutyl titanate 0.2

[0045] Example 3

[0046] Compared with Example 1, the raw material composition and mass fraction ratio of this example are shown in Table 3;

[0047] Table 3: Composition and mass fraction ratio of raw materials used in Example 3

[0048]

[0049] Example 4

[0050] Compared with Example 1, the raw material composition and mass fraction ratio of this example are shown in Table 4;

[0051] Table 4: Composition and mass fraction ratio of raw materials used in Example 4

[0052] Raw material type raw material Mass fraction Alkyl glycoside Dodecyl Glucoside 5 Polyether polyols Polyoxypropylene triol 20 Amorphous polyester polyol FLP-PA1000N 15 Liquid polyester polyol 7230 15 Tackifying resin Terpene resin 20 Isocyanate Polymethylene polyphenyl polyisocyanate 25 Stabilizer Polyphosphoric acid 0.1 Antioxidants 1135 0.3 catalyst Bismorpholinyl triethyl ether 0.3

[0053] Example 5

[0054] Compared with Example 1, the raw material composition and mass fraction ratio of this example are shown in Table 5;

[0055] Table 5: Composition and mass fraction ratio of raw materials used in Example 5

[0056] Raw material type raw material Mass fraction Alkyl glycoside Octyl Glucoside 3 Polyether polyols Polytetramethylene glycol 28 Amorphous polyester polyol 7130 12 Liquid polyester polyol 7250 13 Tackifying resin Terpene resin 16 Isocyanate Methylene diphenyl diisocyanate 28 Stabilizer Sebacic acid 0.1 Antioxidants 1076 0.5 catalyst Bismorpholinyl diethyl ether 0.2

[0057] Example 6

[0058] Compared with Example 1, the raw material composition and mass fraction ratio of this example are shown in Table 6;

[0059] Table 6: Composition and mass fraction ratio of raw materials used in Example 6

[0060] Raw material type raw material Mass fraction Alkyl glycoside Dodecyl Glucoside 5 Polyether polyols Polyoxypropylene glycol 30 Amorphous polyester polyol 7130 15 Liquid polyester polyol 7250 20 Tackifying resin / 0 Isocyanate Methylene diphenyl diisocyanate 30 Stabilizer Azelaic acid 0.1 Antioxidants 168 0.4 catalyst Dimorpholine polyoxyethylene ether 0.1

[0061] Example 7

[0062] Compared with Example 1, the raw material composition and mass fraction ratio of this example are shown in Table 7;

[0063] Table 7: Composition and mass fraction ratio of raw materials used in Example 7

[0064] Raw material type raw material Mass fraction Alkyl glycoside Dodecyl Glucoside 1 Polyether polyols Polyoxypropylene glycol 34 Amorphous polyester polyol 7130 15 Liquid polyester polyol 7250 20 Tackifying resin / 0 Isocyanate Methylene diphenyl diisocyanate 30 Stabilizer Azelaic acid 0.1 Antioxidants 168 0.4 catalyst Dimorpholine polyoxyethylene ether 0.1

[0065] Performance Testing

[0066] In summary, the products obtained in the above-mentioned Examples 1-7: reactive polyurethane hot melt adhesive, and similar commercially available reactive polyurethane hot melt adhesive products were laminated and applied to the same batch of PP and PE low surface energy material films (the dyne value of the low surface energy material film used in the actual experiment was 28-30), and the specific test results are shown in Table 8.

[0067]

[0068]

[0069] It can be seen that the reactive polyurethane hot melt adhesives prepared in Examples 1-7 have excellent bonding strength when applied to low surface energy materials rich in plasticizers, and their final peel strength generally exceeds 30N / 25mm. Among them, Examples 6 and 7 illustrate that in the same formulation system, increasing the amount of alkyl polyglycoside within a certain range can effectively improve the initial bonding strength and final bonding strength of the reactive polyurethane hot melt adhesive prepared to the low surface energy substrate.

[0070] Specifically, after the reactive polyurethane hot melt adhesive prepared by the present invention is applied to the low surface energy material for 1 minute, its initial peel strength is significantly higher than similar products on the market, among which the initial peel strength for PP material can reach up to 8.2N / 25mm, and the initial peel strength for PE material can reach up to 5.1N / 25mm.

[0071] In addition, the reactive polyurethane hot melt adhesive prepared by the present invention also maintains an excellent final bonding effect on low surface energy materials. Specifically, after the reactive polyurethane hot melt adhesive of the present invention is applied to low surface energy materials for 24 hours, its final peel strength is significantly higher than similar products on the market, among which the final peel strength for PP materials can reach up to 45.7N / 25mm, and the final peel strength for PE materials can reach up to 40.0N / 25mm.

[0072] Based on this, the reactive polyurethane hot melt adhesive of the present invention can also achieve good bonding effect at low surface energy interfaces. In contrast, the initial peel strength of similar HMPUR products on the market is poor, and the final peel strength is not high. Insufficient interface wetting will lead to interface damage, and the bonded low surface energy material film can be easily torn off.

[0073] The present invention can have other forms of embodiments according to the above preparation method, which are not listed one by one. Therefore, any simple modification, equivalent change and modification made to the above embodiments by any technician familiar with the profession according to the technical essence of the present invention without departing from the scope of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A reactive polyurethane hot melt adhesive for laminating low surface energy materials, characterized in that: The invention comprises the following components in parts by weight: 1-5 parts of alkyl polyglycoside, 10-30 parts of polyether polyol, 10-20 parts of amorphous polyester polyol, 10-20 parts of liquid polyester polyol, 0-20 parts of tackifying resin, 20-30 parts of isocyanate, 0.01-0.1 parts of stabilizer, 0.1-0.5 parts of antioxidant and 0.1-0.3 parts of catalyst; The carbon chain length of the alkyl glycoside is ≥6; The amorphous polyester polyol is an aromatic polyester polyol; its glass transition temperature is greater than 15°C, and its hydroxyl value is 30mgKOH / g-120mgKOH / g; The liquid polyester polyol is an aromatic polyester polyol or an aliphatic polyester polyol; its glass transition temperature is less than -25°C, and its hydroxyl value is 18 mgKOH / g-34 mgKOH / g.

2. A reactive polyurethane hot melt adhesive for laminating low surface energy materials as claimed in claim 1, characterized in that: The polyether polyol is one of polyoxypropylene glycol, polyoxyethylene glycol, polyoxypropylene-ethylene glycol, polyoxypropylene triol and polytetramethylene ether glycol, and has a hydroxyl value of 18 mgKOH / g-120 mgKOH / g.

3. The reactive polyurethane hot melt adhesive for laminating low surface energy materials according to claim 1, characterized in that: The polyacid of the amorphous polyester polyol is selected from one or more of terephthalic acid, phthalic anhydride, and isophthalic acid; the polyol is selected from one or more of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 1,4-cyclohexanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol.

4. A reactive polyurethane hot melt adhesive for laminating low surface energy materials as claimed in claim 1, characterized in that: The polyacid of the liquid polyester polyol is selected from one or more of terephthalic acid, phthalic anhydride, isophthalic acid, adipic acid, and sebacic acid; the polyol is selected from one or more of diethylene glycol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,3-propanediol, 1,4-cyclohexanediol, neopentyl glycol, and 3-methyl-1,5-pentanediol.

5. The reactive polyurethane hot melt adhesive for laminating low surface energy materials according to claim 1, characterized in that: The tackifying resin is selected from one or more of acrylic resin, petroleum resin, rosin resin and terpene resin.

6. The reactive polyurethane hot melt adhesive for laminating low surface energy materials according to claim 1, characterized in that: The isocyanate is one of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, isophorone diisocyanate toluene diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate.

7. The reactive polyurethane hot melt adhesive for laminating low surface energy materials according to claim 1, characterized in that: The stabilizer is one of phosphoric acid, polyphosphoric acid, p-toluenesulfonyl isocyanate, sebacic acid, benzoyl chloride, and azelaic acid.

8. The reactive polyurethane hot melt adhesive for laminating low surface energy materials according to claim 1, characterized in that: The antioxidant is one of antioxidant 1010, antioxidant 168, antioxidant 1035, antioxidant 1076, antioxidant 1135, antioxidant 5057 and triphenyl phosphite.

9. The reactive polyurethane hot melt adhesive for laminating low surface energy materials according to claim 1, characterized in that: The catalyst is one of dibutyltin dilaurate, stannous octoate, tetrabutyl titanate, triethylenediamine, 1,4-dimethylpiperazine, bismorpholinyl diethyl ether, bismorpholinyl triethyl ether and dimorpholine polyoxyethylene ether.

10. A method for preparing a reactive polyurethane hot melt adhesive for laminating low surface energy materials according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Put the stabilizer, antioxidant and tackifying resin into a vacuum reactor, heat it to 130° C.-140° C., mix and stir to melt for 1 h-2 h; (2) adding alkyl polyglycoside, polyether polyol, amorphous polyester polyol and liquid polyester polyol, stirring and melting at 130° C.-140° C., and dehydrating under vacuum ≤-0.098 MPa for 1 h-2 h, wherein the water content after dehydration is ≤500 ppm; (3) Cooling to 95°C-105°C, adding isocyanate, mixing and stirring evenly, heating to 115°C-125°C, and reacting for 1h-1.5h; (4) adding a catalyst and performing a vacuum degassing reaction at 115° C. to 125° C. for 0.5 h to 1 h; (5) After discharging, sealing and packaging, the reactive polyurethane hot melt adhesive is obtained.

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