Polyurethane hot melt adhesive for edge sealing as well as preparation method and application of polyurethane hot melt adhesive

Abstract

The invention relates to a polyurethane hot melt adhesive for edge sealing and a preparation method and application thereof. The polyurethane hot melt adhesive for edge sealing is prepared from the following components in parts by weight: 100 parts of crystalline polyester polyol, 140 to 300 parts of liquid polyester polyol, 20 to 120 parts of amorphous polyester polyol, 10 to 100 parts of polyolefin, 10 to 40 parts of copolyester, 50 to 200 parts of filler, 20 to 80 parts of isocyanate A and 1 to 10 parts of isocyanate B, the molar ratio of the total number of isocyanate groups contained in the preparation raw materials to the total number of hydroxyl contained in the preparation raw materials is 1.3-1.6. The polyurethane hot melt adhesive for edge sealing provided by the invention has the characteristics of long opening time and good adhesive property.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyurethane materials, in particular to a polyurethane hot melt adhesive for edge sealing and a preparation method and application thereof. BACKGROUND

[0002] In the field of building and home decoration, the edge parts of some furniture and decorative components often need to be edge sealed and decorated, such as the edges of materials such as solid wood, particle board and wood-plastic board. Through edge sealing and decoration, the erosion of the material by moisture, acid, alkali, microorganisms and pests in the environment can be prevented, and the furniture or decorative components can be made more beautiful. Generally, edge sealing and decoration processes require edge sealing glue, which is applied and pressed by a device that matches the profile of the edge sealing, and the most important requirement in the decoration aspect is to ensure rapid curing between the base material and the decorative film, and the adhesion is compact and firm.

[0003] The edge sealing glue currently used on the market is mainly high-temperature resistant hot melt glue. Its adhesion is achieved by melting the hot melt glue into a liquid using a hot melt machine, and then sending it to the surface of the adherend through spraying, tank conveying or extrusion. After the hot melt glue cools down, the bonding is completed. It has a certain bonding strength for general materials, but due to its high-temperature reversible characteristics, there is a risk of rebounding at high temperatures on the bonded surface. On the other hand, the base materials for edge sealing are becoming more and more diverse, including wood-plastic, solid wood, particle board, etc. The application of traditional hot melt glue is increasingly limited, and it cannot achieve good bonding for different base materials.

[0004] Reaction-type polyurethane hot melt adhesive (PUR hot melt adhesive for short) has developed rapidly in recent years due to its advantages of both polyurethane adhesive and thermoplastic adhesive. For example, CN113388359A discloses a reaction-type wet-curable polyurethane hot melt adhesive for furniture and a preparation method thereof. The adhesive is made of polyester polyol, polyether polyol, EVA resin, polyisocyanate, high-molecular-weight copolyester and chain extender. The prepared polyurethane hot melt adhesive has good initial adhesion strength and excellent wet heat resistance, and good adhesion to different base materials. However, the open time is short, and the surface drying speed is too fast at low temperatures (<0℃) in winter, resulting in insufficient wetting of the base material and a decrease in adhesion strength.

[0005] Therefore, there is an urgent need for a polyurethane hot melt adhesive for edge sealing that can extend the open time at low temperatures and has high adhesion strength. SUMMARY

[0006] To solve the above technical problems, the present application provides a polyurethane hot melt adhesive for edge sealing and a preparation method and application thereof. The polyurethane hot melt adhesive for edge sealing has the characteristics of long open time, good adhesion performance and high peel strength.

[0007] To achieve this purpose, the present application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a polyurethane hot melt adhesive for edge sealing, the raw materials for preparing the polyurethane hot melt adhesive for edge sealing include the following components in parts by weight: crystalline polyester polyol 100 parts, liquid polyester polyol 140-300 parts (for example, 160 parts, 180 parts, 200 parts, 220 parts, 240 parts, 260 parts, or 280 parts, etc.), amorphous polyester polyol 20-120 parts (30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, or 110 parts, etc.), polyolefin 10-100 parts (20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, or 90 parts, etc.), copolyester 10-40 parts (for example, 13 parts, 16 parts, 19 parts, 22 parts, 25 parts, 28 parts, 31 parts, 34 parts, or 37 parts, etc.), filler 50-200 parts (for example, 70 parts, 90 parts, 110 parts, 130 parts, 150 parts, 170 parts, or 190 parts, etc.), isocyanate A 20-80 parts (for example, 30 parts, 40 parts, 50 parts, 60 parts, or 70 parts, etc.), and isocyanate B 1-10 parts (for example, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, or 9 parts, etc.); the molar ratio of the total number of isocyanate groups contained in the raw materials to the total number of hydroxyl groups is 1.3-1.6 (for example, 1.35, 1.4, 1.45, 1.5, or 1.55, etc.).

[0009] The molar ratio of isocyanate groups (-NCO) to hydroxyl groups (-OH) is the isocyanate index (R value), that is, the isocyanate index in the present application is 1.3-1.6 (for example, 1.35, 1.4, 1.45, 1.5, or 1.55, etc.).

[0010] In the present application, the isocyanate groups in the raw materials for preparing the polyurethane hot melt adhesive for edge sealing come from isocyanate A and isocyanate B, and the hydroxyl groups come from crystalline polyester polyol, liquid polyester polyol, amorphous polyester polyol, and copolyester.

[0011] In the present application, by compounding crystalline polyester polyol, liquid polyester polyol, amorphous polyester polyol, polyolefin, copolyester, filler, isocyanate A, and isocyanate B, and controlling the isocyanate index in the range of 1.3-1.6, the polyurethane hot melt adhesive for edge sealing prepared has the characteristics of long open time, good bonding performance, and high peel strength.

[0012] Preferably, the hydroxyl value of the crystalline polyester polyol is 10 mgKOH / g-120 mgKOH / g, for example, 30 mgKOH / g, 50 mgKOH / g, 70 mgKOH / g, 90 mgKOH / g, or 110 mgKOH / g, etc.

[0013] Preferably, the crystalline polyester polyol has a melting point of 56°C to 100°C, such as 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C, etc.

[0014] Preferably, the crystalline polyester polyol comprises Evonik Dynacoll 7381 and / or Evonik Dynacoll 7380.

[0015] Preferably, the liquid polyester polyol has a hydroxyl value of 15 mg KOH / g to 50 mg KOH / g, such as 20 mg KOH / g, 25 mg KOH / g, 30 mg KOH / g, 35 mg KOH / g, 40 mg KOH / g, or 45 mg KOH / g, etc.

[0016] Preferably, the liquid polyester polyol comprises Evonik Dynacoll 7230 and / or Evonik Dynacoll 7250.

[0017] Preferably, the amorphous polyester polyol has a hydroxyl value of 20 mg KOH / g to 70 mg KOH / g, such as 25 mg KOH / g, 30 mg KOH / g, 35 mg KOH / g, 40 mg KOH / g, 45 mg KOH / g, 50 mg KOH / g, 55 mg KOH / g, 60 mg KOH / g, or 65 mg KOH / g, etc.

[0018] Preferably, the amorphous polyester polyol has a glass transition temperature of 20°C to 50°C, such as 25°C, 30°C, 35°C, 40°C, or 45°C, etc.

[0019] Preferably, the amorphous polyester polyol comprises Evonik Dynacoll 7130 and / or Evonik Dynacoll 7150.

[0020] Preferably, the polyolefin comprises an alpha-olefin polymer.

[0021] Preferably, the alpha-olefin polymer is prepared from a raw material comprising any one or a combination of at least two of ethylene, propylene, 1-butene, isobutylene, 1-pentene, 1-hexene, 1-octene, or 4-methyl-1-pentene.

[0022] Preferably, the polyolefin has a softening point of < 150°C, such as 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or 140°C, etc.

[0023] Preferably, the copolymerized polyester has a hydroxyl value of 3 mg KOH / g to 10 mg KOH / g, such as 3 mg KOH / g, 4 mg KOH / g, 5 mg KOH / g, 6 mg KOH / g, 7 mg KOH / g, 8 mg KOH / g, or 9 mg KOH / g, etc.

[0024] Preferably, the softening point of the copolyester is 80°C to 120°C, for example, 95°C, 100°C, 105°C, 110°C or 115°C.

[0025] Preferably, the copolyester comprises Evonik Dynacoll S1401 and / or Evonik Dynacoll S1402.

[0026] Preferably, the filler comprises any one or a combination of at least two of the following: hydrophobic fumed silica, talc, montmorillonite, calcium carbonate, carbon black, or silica powder.

[0027] Preferably, the D90 particle size of the filler is ≤20μm, such as 2μm, 4μm, 6μm, 8μm, 10μm, 12μm, 14μm, 16μm or 18μm.

[0028] Preferably, the isocyanate A includes any one or a combination of at least two of MDI-50, 4,4'-MDI, or MDI-100L.

[0029] Preferably, the isocyanate B comprises MDI-50.

[0030] In this invention, MDI-50 is a mixture of 2,4-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, including but not limited to WanNATE MDI-50 and / or Covestro Desmodur 2460; 4,4'-MDI is 4,4'-diphenylmethane diisocyanate; MDI-100L is a modified diphenylmethane diisocyanate, including but not limited to WanNATE MDI-50. MDI-100L and / or BASF Suprasec 5005.

[0031] In a second aspect, the present invention provides a method for preparing polyurethane hot melt adhesive for edge sealing as described in the first aspect, the method comprising the following steps: mixing and reacting crystalline polyester polyol, liquid polyester polyol, amorphous polyester polyol, polyolefin, copolyester, filler, isocyanate A and isocyanate B to obtain the polyurethane hot melt adhesive for edge sealing.

[0032] Preferably, the preparation method includes the following steps: mixing crystalline polyester polyol, liquid polyester polyol, amorphous polyester polyol, polyolefin, copolyester and filler, vacuum dehydrating, adding isocyanate A for a first reaction, adding isocyanate B for a second reaction, to obtain the polyurethane hot melt adhesive for sealing edges.

[0033] Preferably, the vacuum dehydration temperature is 110-130°C, such as 112°C, 114°C, 116°C, 118°C, 120°C, 122°C, 124°C, 126°C, or 128°C.

[0034] Preferably, the vacuum dehydration time is 1 to 3 hours, such as 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, or 2.8 hours.

[0035] Preferably, the temperature of the first reaction is 100-120°C (e.g., 102°C, 104°C, 106°C, 108°C, 110°C, 112°C, 114°C, 116°C, or 118°C, etc.), and the time is 1-3 hours (e.g., 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, or 2.8 hours, etc.).

[0036] Preferably, the temperature of the second reaction is 100-120°C (e.g., 102°C, 104°C, 106°C, 108°C, 110°C, 112°C, 114°C, 116°C, or 118°C, etc.), and the time is 20-60 min (e.g., 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, etc.).

[0037] Thirdly, the present invention provides an application of the polyurethane hot melt adhesive for edge sealing as described in the first aspect in edge sealing of furniture or decorative components.

[0038] Compared with the prior art, the present invention has at least the following beneficial effects:

[0039] This invention relates to a polyurethane hot melt adhesive for edge sealing, prepared by compounding crystalline polyester polyol, liquid polyester polyol, amorphous polyester polyol, polyolefin, copolyester, filler, isocyanate A, and isocyanate B. This adhesive features a long open time, good adhesion, and high peel strength. The open time of the polyurethane hot melt adhesive for edge sealing is ≥15s, the peel strength when bonded to particleboard is ≥3.5N / mm, and the peel strength when bonded to solid wood board is ≥3.0N / mm. Detailed Implementation

[0040] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0041] The sources of some of the raw materials in the following examples and comparative examples are as follows:

[0042] MDI-50: Covestro Desmodur 2460.

[0043] MDI-100L: Wanhua MDI-100L.

[0044] Example 1

[0045] This embodiment provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The raw materials for preparing the polyurethane hot melt adhesive for edge sealing include the following components: 100 kg of crystalline polyester polyol (Evonik Dynacoll 7380 polyester polyol, melting point 70℃), 200 kg of liquid polyester polyol (Evonik Dynacoll 7250 polyester polyol), 80 kg of amorphous polyester polyol (Evonik Dynacoll 7130 polyester polyol), 40 kg of polyolefin (Evonik VESTOPLAST 508 amorphous polyolefin, softening point 84℃), 20 kg of copolyester (Dynacoll S1402, softening point 100℃, hydroxyl value 7 mgKOH / g), 100 kg of filler (Omia 2JI heavy calcium carbonate), 30 kg of isocyanate A (4,4'-MDI), and 4 kg of isocyanate B (MDI-50); wherein, the isocyanate index is 1.50.

[0046] The preparation method includes the following steps: crystalline polyester polyol, liquid polyester polyol, amorphous polyester polyol, polyolefin, copolyester and filler are added to a planetary machine, melted at 130°C and vacuum dehydrated for 2 hours. After testing that the water content is ≤200ppm, the temperature is lowered to 100°C and isocyanate A is added. Vacuum is drawn and the reaction is carried out at 110°C for 1.5 hours. Then isocyanate B is added and the reaction is carried out at 120°C for 30 minutes. The product is discharged to obtain polyurethane hot melt adhesive.

[0047] Example 2

[0048] This embodiment provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The raw materials for preparing the polyurethane hot melt adhesive for edge sealing include the following components: 100 kg of crystalline polyester polyol (Evonik Dynacoll 7381 polyester polyol, melting point 70℃), 200 kg of liquid polyester polyol (Evonik Dynacoll 7250 polyester polyol), 80 kg of amorphous polyester polyol (Evonik Dynacoll 7130 polyester polyol), 40 kg of polyolefin (Evonik VESTOPLAST 508 amorphous polyolefin, softening point 84℃), 20 kg of copolyester (Dynacoll S1401, softening point 97℃, hydroxyl value 7 mgKOH / g), 100 kg of filler (Omia 2JI heavy calcium carbonate), 30 kg of isocyanate A (4,4'-MDI), and 4 kg of isocyanate B (MDI-50); wherein, the isocyanate index is 1.50.

[0049] The preparation method includes the following steps: crystalline polyester polyol, liquid polyester polyol, amorphous polyester polyol, polyolefin, copolyester and filler are added to a planetary machine, melted at 130°C and vacuum dehydrated for 2 hours. After testing that the water content is ≤200ppm, the temperature is lowered to 100°C and isocyanate A is added. Vacuum is drawn and the reaction is carried out at 110°C for 1.5 hours. Then isocyanate B is added and the reaction is carried out at 120°C for 30 minutes. The product is discharged to obtain polyurethane hot melt adhesive.

[0050] Example 3

[0051] This embodiment provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The raw materials for preparing the polyurethane hot melt adhesive for edge sealing include the following components: 100 kg of crystalline polyester polyol (Evonik Dynacoll 7381 polyester polyol, melting point 70℃), 150 kg of liquid polyester polyol (Evonik Dynacoll 7250 polyester polyol), 80 kg of amorphous polyester polyol (Evonik Dynacoll 7130 polyester polyol), 60 kg of polyolefin (Evonik VESTOPLAST 508 amorphous polyolefin, softening point 84℃), 20 kg of copolyester (Dynacoll S1401, softening point 97℃, hydroxyl value 7 mgKOH / g), 100 kg of filler (Omia 2JI heavy calcium carbonate), 25 kg of isocyanate A (4,4'-MDI), and 3 kg of isocyanate B (MDI-50); wherein, the isocyanate index is 1.37.

[0052] The preparation method includes the following steps: crystalline polyester polyol, liquid polyester polyol, amorphous polyester polyol, polyolefin, copolyester and filler are added to a planetary machine, melted at 130°C and vacuum dehydrated for 2 hours. After testing that the water content is ≤200ppm, the temperature is lowered to 100°C and isocyanate A is added. Vacuum is drawn and the reaction is carried out at 110°C for 1.5 hours. Then isocyanate B is added and the reaction is carried out at 120°C for 30 minutes. The product is discharged to obtain polyurethane hot melt adhesive.

[0053] Example 4

[0054] This embodiment provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The raw materials for preparing the polyurethane hot melt adhesive for edge sealing include the following components: 100 kg of crystalline polyester polyol (Evonik Dynacoll 7381 polyester polyol, melting point 70℃), 250 kg of liquid polyester polyol (Evonik Dynacoll 7250 polyester polyol), 80 kg of amorphous polyester polyol (Evonik Dynacoll 7130 polyester polyol), 80 kg of polyolefin (Evonik VESTOPLAST 508 amorphous polyolefin, softening point 84℃), 20 kg of copolyester (Dynacoll S1401, softening point 97℃, hydroxyl value 7 mgKOH / g), 100 kg of filler (Omia 2JI heavy calcium carbonate), 33 kg of isocyanate A (4,4'-MDI), and 6 kg of isocyanate B (MDI-50); wherein, the isocyanate index is 1.55.

[0055] The preparation method includes the following steps: crystalline polyester polyol, liquid polyester polyol, amorphous polyester polyol, polyolefin, copolyester and filler are added to a planetary machine, melted at 130°C and vacuum dehydrated for 2 hours. After testing that the water content is ≤200ppm, the temperature is lowered to 100°C and isocyanate A is added. Vacuum is drawn and the reaction is carried out at 110°C for 1.5 hours. Then isocyanate B is added and the reaction is carried out at 120°C for 30 minutes. The product is discharged to obtain polyurethane hot melt adhesive.

[0056] Example 5

[0057] This embodiment provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this embodiment and Example 4 is that isocyanate A (4,4'-MDI) is replaced with isocyanate A (MDI-50), and the addition mass of isocyanate A (MDI-50) is adjusted accordingly to make the isocyanate index 1.55. Other conditions are the same as in Example 4.

[0058] Example 6

[0059] This embodiment provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this embodiment and Example 4 is that isocyanate A (4,4'-MDI) is replaced with isocyanate A (MDI-100L), and the amount of isocyanate A (MDI-100L) added is adjusted to make the isocyanate index 1.55. Other conditions are the same as in Example 4.

[0060] Example 7

[0061] This embodiment provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this embodiment and Embodiment 4 is that the polyolefin (Evonik VESTOPLAST 508 amorphous polyolefin, softening point 84°C) is replaced with the same mass of polyolefin (Evonik VESTOPLAST 408 amorphous polyolefin, softening point 114°C), while other conditions are the same as in Embodiment 4.

[0062] Example 8

[0063] This embodiment provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this embodiment and Example 4 is that the mass of the copolyester (Dynacoll S1401, softening point 97℃, hydroxyl value 7mgKOH / g) is adjusted to 10kg, and the mass of isocyanate A (4,4'-MDI) is adjusted accordingly to make the isocyanate index 1.55. Other conditions are the same as in Example 4.

[0064] Example 9

[0065] This embodiment provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this embodiment and Example 4 is that the mass of the copolyester (Dynacoll S1401, softening point 97℃, hydroxyl value 7mgKOH / g) is adjusted to 40kg, and the mass of isocyanate A (4,4'-MDI) is adjusted accordingly to make the isocyanate index 1.55. Other conditions are the same as in Example 4.

[0066] Example 10

[0067] This embodiment provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this embodiment and Embodiment 4 is that the mass of the filler (Omia 2JI heavy calcium carbonate) is adjusted from 100 kg to 50 kg, while other conditions are the same as in Embodiment 4.

[0068] Example 11

[0069] This embodiment provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this embodiment and Embodiment 4 is that the mass of the filler (Omia 2JI heavy calcium carbonate) is adjusted from 100 kg to 200 kg, while other conditions are the same as in Embodiment 4.

[0070] Comparative Example 1

[0071] This comparative example provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this example and Example 1 is that the mass of crystalline polyester polyol (Evonik Dynacoll 7380 polyester polyol) is adjusted to 380 kg, liquid polyester polyol (Evonik Dynacoll 7250 polyester polyol) and amorphous polyester polyol (Evonik Dynacoll 7130 polyester polyol) are not added, and the mass of isocyanate A (4,4'-MDI) is adjusted accordingly to make the isocyanate index 1.50. Other conditions are the same as in Example 1.

[0072] Comparative Example 2

[0073] This comparative example provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this example and Example 1 is that the mass of liquid polyester polyol (Evonik Dynacoll 7250 polyester polyol) is adjusted to 380 kg, crystalline polyester polyol (Evonik Dynacoll 7380 polyester polyol) and amorphous polyester polyol (Evonik Dynacoll 7130 polyester polyol) are not added, and the mass of isocyanate A (4,4'-MDI) is adjusted accordingly to make the isocyanate index 1.50. Other conditions are the same as in Example 1.

[0074] Comparative Example 3

[0075] This comparative example provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this example and Example 1 is that the mass of amorphous polyester polyol (Evonik Dynacoll 7130 polyester polyol) is adjusted to 380 kg, and crystalline polyester polyol (Evonik Dynacoll 7380 polyester polyol) and liquid polyester polyol (Evonik Dynacoll 7250 polyester polyol) are not added. The mass of isocyanate A (4,4'-MDI) is also adjusted accordingly to make the isocyanate index 1.50. Other conditions are the same as in Example 1.

[0076] Comparative Example 4

[0077] This comparative example provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this and Example 1 is that no polyolefin (Evonik VESTOPLAST 508 amorphous polyolefin, softening point 84°C) is added, while other conditions are the same as in Example 1.

[0078] Comparative Example 5

[0079] This comparative example provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this and Example 1 is that no copolyester (Dynacoll S1402, softening point 100℃, hydroxyl value 7mgKOH / g) is added, and the addition mass of isocyanate A (4,4'-MDI) is adjusted accordingly to make the isocyanate index 1.50. Other conditions are the same as in Example 1.

[0080] Comparative Example 6

[0081] This comparative example provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this example and Example 1 is that the mass of liquid polyester polyol (Evonik Dynacoll 7250 polyester polyol) is adjusted to 100 kg, the mass of amorphous polyester polyol (Evonik Dynacoll 7130 polyester polyol) is adjusted to 140 kg, and the mass of added isocyanate A (4,4'-MDI) is adjusted accordingly to make the isocyanate index 1.50. Other conditions are the same as in Example 1.

[0082] Comparative Example 7

[0083] This comparative example provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this example and Example 1 is that the mass of isocyanate A (4,4'-MDI) is adjusted so that the isocyanate index in the raw materials for preparing the polyurethane hot melt adhesive for edge sealing is 1.71. Other conditions are the same as in Example 1.

[0084] Comparative Example 8

[0085] This comparative example provides a polyurethane hot melt adhesive for edge sealing and its preparation method. The difference between this and Example 1 is that isocyanate B (MDI-50) is not added, and the addition mass of isocyanate A (4,4'-MDI) is adjusted accordingly to make the isocyanate index 1.50. The preparation method does not include the step of adding isocyanate B (MDI-50) for reaction. Other conditions are the same as in Example 1.

[0086] The following performance tests were conducted on the polyurethane hot melt adhesives for edge sealing provided in Examples 1-11 and Comparative Examples 1-8.

[0087] (1) Open time: The test was conducted in accordance with HG / T 3716-2003 "Determination of open time of hot melt adhesive", with an adhesive application temperature of 150℃.

[0088] (2) Melt viscosity: The test was conducted in accordance with HG / T 3660-1999 "Determination of melt viscosity of hot melt adhesives" at a test temperature of 150℃.

[0089] (3) Evaluation of bonding performance: The bonding performance of the PVC edge banding strip with a surface dyne value of 37 was verified by bonding it to the particleboard or solid wood board using polyurethane hot melt adhesive for edge banding. The peel force test method was carried out in accordance with GB / T2792-2014 "Test method for peel strength of adhesive tape".

[0090] Preparation of standard peel-off parts: Using an edge banding machine, PVC edge banding strips are bonded to particleboard or solid wood board using polyurethane hot melt adhesive. The adhesive application rate is 250g / m². 2 Then, the samples were cut into lengths of 400±10mm. Three samples were prepared according to the above requirements, placed for 10 minutes, and then tested on a tensile testing machine at a test speed of 5mm / s. The peel force test data and failure modes were recorded.

[0091] The test results are shown in Table 1 below.

[0092] Table 1

[0093]

[0094]

[0095] As can be seen from the test results in Table 1, the polyurethane hot melt adhesives for edge sealing provided in Examples 1 to 11 have an open time ≥15s, a peel force ≥3.5N / mm when bonded to particleboard, and a peel force ≥3.0N / mm when bonded to solid wood board. They have the characteristics of long open time and good bonding performance to particleboard and solid wood board.

[0096] Compared with Example 4, if isocyanate A (4,4'-MDI) is replaced with isocyanate A (MDI-50) (Example 5), the open time of the prepared polyurethane hot melt adhesive for edge sealing increases, but the bonding performance to particleboard and solid wood board decreases.

[0097] As can be seen from the comparison of Examples 1 and Comparative Examples 1-3, the combined use of crystalline polyester polyol, liquid polyester polyol, and amorphous polyester polyol plays an important role in the technical effect of this invention. The absence of any component will significantly reduce the initial adhesive strength and peel strength of the resulting polyurethane hot melt adhesive for edge sealing. Examples 1 and Comparative Example 4 show that the adhesive performance of the resulting polyurethane hot melt adhesive for edge sealing decreases without the addition of polyolefin. Examples 1 and Comparative Example 5 show that the adhesive performance of the resulting polyurethane hot melt adhesive for edge sealing decreases without the addition of copolyester. In summary, the technical effect of the polyurethane hot melt adhesive for edge sealing described in this invention is due to the synergistic effect of its components; none can be omitted.

[0098] As can be seen from Example 1 and Comparative Example 6, if the mass of liquid polyester polyol decreases and the mass of amorphous polyester polyol increases, the bonding performance of the polyurethane hot melt adhesive for edge sealing decreases and the open time is significantly shortened. Therefore, it can be seen that if the weight proportions of each component in the raw materials for preparing the polyurethane hot melt adhesive for edge sealing are controlled within a specific range, the performance of the prepared polyurethane hot melt adhesive for edge sealing will be better.

[0099] As can be seen from Example 1 and Comparative Example 7, if the isocyanate index in the raw materials for preparing polyurethane hot melt adhesive for edge sealing is too high, the bonding performance of the polyurethane hot melt adhesive for edge sealing will be low.

[0100] As can be seen from Example 1 and Comparative Example 8, if isocyanate B is not added to the raw materials for preparing polyurethane hot melt adhesive for edge sealing, the open time of the polyurethane hot melt adhesive for edge sealing is short and the bonding performance is low.

[0101] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A polyurethane hot melt adhesive for edge sealing, characterized in that, The raw materials for preparing the polyurethane hot melt adhesive for edge sealing include the following components by weight: 100 parts of crystalline polyester polyol, 140-300 parts of liquid polyester polyol, 20-120 parts of amorphous polyester polyol, 10-100 parts of polyolefin, 10-40 parts of copolyester, 50-200 parts of filler, 20-80 parts of isocyanate A and 1-10 parts of isocyanate B; the molar ratio of the total number of isocyanate groups to the total number of hydroxyl groups in the raw materials is 1.3-1.

6.

2. The polyurethane hot melt adhesive for edge sealing according to claim 1, characterized in that, The hydroxyl value of the crystalline polyester polyol is 10 mg KOH / g to 120 mg KOH / g; Preferably, the melting point of the crystalline polyester polyol is 56°C to 100°C; Preferably, the hydroxyl value of the liquid polyester polyol is 15 mg KOH / g to 50 mg KOH / g; Preferably, the hydroxyl value of the amorphous polyester polyol is 20 mg KOH / g to 70 mg KOH / g; Preferably, the glass transition temperature of the amorphous polyester polyol is 20°C to 50°C.

3. The polyurethane hot melt adhesive for edge sealing according to claim 1 or 2, characterized in that, The polyolefin includes α-olefin polymers; Preferably, the raw materials for preparing the α-olefin polymer include any one or a combination of at least two of ethylene, propylene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-octene or 4-methyl-1-pentene. Preferably, the softening point of the polyolefin is <150°C.

4. The polyurethane hot melt adhesive for edge sealing according to any one of claims 1 to 3, characterized in that, The hydroxyl value of the copolyester is 3 mg KOH / g to 10 mg KOH / g; Preferably, the softening point of the copolyester is 80°C to 120°C.

5. The polyurethane hot melt adhesive for edge sealing according to any one of claims 1 to 4, characterized in that, The filler includes any one or a combination of at least two of the following: hydrophobic fumed silica, talc, montmorillonite, calcium carbonate, carbon black, or silica powder. Preferably, the D90 particle size of the filler is ≤20μm.

6. The polyurethane hot melt adhesive for edge sealing according to any one of claims 1 to 5, characterized in that, The isocyanate A includes any one or a combination of at least two of MDI-50, 4,4'-MDI, or MDI-100L.

7. The polyurethane hot melt adhesive for edge sealing according to claims 1 to 6, characterized in that, The isocyanate B includes MDI-50.

8. A method for preparing a polyurethane hot melt adhesive for edge sealing as described in any one of claims 1 to 7, characterized in that, The preparation method includes the following steps: mixing and reacting crystalline polyester polyol, liquid polyester polyol, amorphous polyester polyol, polyolefin, copolyester, filler, isocyanate A and isocyanate B to obtain the polyurethane hot melt adhesive for sealing edges.

9. The preparation method according to claim 8, characterized in that, The preparation method includes the following steps: mixing crystalline polyester polyol, liquid polyester polyol, amorphous polyester polyol, polyolefin, copolyester and filler, vacuum dehydrating, adding isocyanate A for a first reaction, adding isocyanate B for a second reaction, to obtain the polyurethane hot melt adhesive for sealing edges. Preferably, the temperature for vacuum dehydration is 110–130°C; Preferably, the vacuum dehydration time is 1 to 3 hours; Preferably, the temperature of the first reaction is 100–120°C, and the time is 1–3 hours; Preferably, the temperature of the second reaction is 100–120°C and the time is 20–60 min.

10. The application of a polyurethane hot melt adhesive for edge sealing as described in any one of claims 1 to 7 in sealing the edges of furniture or decorative components.

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