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

Abstract

The invention discloses a reaction type polyurethane hot melt adhesive for edge sealing, and the reaction type polyurethane hot melt adhesive for edge sealing comprises the following raw material components in parts by weight: 100-110 parts of polyester polyol; 20 to 25 parts of diisocyanate; 0.1 to 0.3 part of a catalyst; 35 to 50 parts of tackifying resin; 20 to 30 parts of filler; 0.2 to 0.3 part of an auxiliary agent; the filler comprises barium sulfate and hollow glass beads, and the mass ratio of the barium sulfate to the hollow glass beads is (9-11): 1. According to the reaction type polyurethane hot melt adhesive for edge sealing, the barium sulfate and the hollow glass beads are adopted as filler, the barium sulfate can improve the initial bonding strength, meanwhile, the melt viscosity of the barium sulfate is smaller than that of calcium carbonate, and the barium sulfate is greatly helpful to the bonding strength at low temperature; the hollow glass beads can improve the fluidity of the glue, the opening time is long, so that the glue can be better wetted in winter, and the prepared reactive polyurethane hot melt adhesive for edge sealing does not rebound in summer, still has better bonding strength in winter and can be universal in winter and summer.

Description

Technical Field

[0001] The invention belongs to the technical field of reactive polyurethane hot melt adhesives, and in particular relates to a reactive polyurethane hot melt adhesive for edge banding in the woodworking industry and a preparation method of the reactive polyurethane hot melt adhesive. Background Art

[0002] Edge banding is an important process in furniture manufacturing. This process involves using specific materials, such as PVC, ABS or other materials, to seal the edges of the board by gluing and pressing. The purpose of edge banding is mainly to enhance the aesthetics of the board or furniture, and it can also play a protective role, such as moisture-proof, moth-proof, and extend the service life of the product. In addition, edge banding can effectively block the release of harmful gases that may exist inside the board, such as formaldehyde, thus having an environmentally friendly effect.

[0003] Commonly used edge banding adhesives are divided into EVA hot melt adhesive and reactive polyurethane hot melt adhesive (PUR). Compared with PUR, EVA hot melt adhesive uses a large amount of adhesive, is easy to overflow, has obvious glue lines, and has poor temperature and water resistance. Therefore, PUR hot melt adhesive is gradually replacing EVA hot melt adhesive to become the mainstream of edge banding adhesive.

[0004] The active -NCO groups in reactive polyurethane hot melt adhesive (PUR) will undergo cross-linking and curing reactions with moisture in the environment, polar groups on the surface of the adherend, and adsorbed moisture. It has a 100% solid content and is solvent-free, making it a green and environmentally friendly adhesive. Patent 201810309379.2 discloses a method for preparing a thermoplastic polyurethane furniture edge-sealing hot melt adhesive, and Patent 201910396158.8 discloses a reactive polyurethane hot melt adhesive for edge sealing, which has excellent initial adhesion and final strength, a low melting temperature, and an extremely short curing time.

[0005] However, existing reactive polyurethane hot melt adhesives, including the above-mentioned patented solution, have the following problems when used for woodworking edge banding: they are prone to rebound when the temperature is high in summer, and the edge banding strips are prone to fall off due to insufficient bonding strength when the temperature is low in winter, and cannot be used in all seasons.

[0006] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed before the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0007] In view of this, in order to overcome the defects of the prior art, the object of the present invention is to provide an improved reactive polyurethane hot melt adhesive for edge sealing.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A reactive polyurethane hot melt adhesive for edge sealing, wherein the reactive polyurethane hot melt adhesive for edge sealing comprises the following raw material components in parts by weight:

[0010]

[0011] The filler includes barium sulfate and hollow glass microspheres, and the mass ratio of the barium sulfate to the hollow glass microspheres is 9-11: 1, preferably 10: 1. Existing adhesive fillers are basically calcium carbonate powder and fumed silica. Using barium sulfate and hollow glass microspheres can reduce melt viscosity and increase fluidity.

[0012] According to some preferred implementation aspects of the present invention, the mesh number of the barium sulfate is 1000-1500 mesh, the water content is <0.1%, the oil absorption is <10mL / 100g, and the whiteness is 90-95. Preferably, the mesh number of the barium sulfate is 1250 mesh, the water content is <0.1%, the oil absorption is <10mL / 100g, and the whiteness is 92.

[0013] According to some preferred implementation aspects of the present invention, the hollow glass microspheres have a true density of 0.4-0.44, a bulk density of 0.21-0.24, and a particle size of 20-30 μm, preferably 25 μm.

[0014] According to some preferred implementation aspects of the present invention, the diisocyanate is one or a mixture of MDI-100 and MDI-50, and the mass ratio of MDI-100 to MDI-50 is 2-4:1, preferably 3:1. MDI has higher activity and lower toxicity, and MDI strength is higher than TDI. At the same time, the mixed use of MDI-100 and MDI-50, on the one hand, ensures the reaction activity and the final bonding strength, and on the other hand, the wet curing reaction will not be too fast to cause colloid skinning.

[0015] According to some preferred implementation aspects of the present invention, the polyester polyol includes crystalline polyester polyol, amorphous polyester polyol or special polyester polyol, and the special polyester polyol is a liquid polyester polyol with two or more components.

[0016] According to some preferred implementation aspects of the present invention, the auxiliary agent is an antioxidant and / or a defoamer, wherein the antioxidant is selected from one or more of 1010, 126 and AO-80, and most preferably AO-80 and 126 are added in a mass ratio of 1:1; the defoamer is preferably one or two of BYK-A535 and BYK-1790 of BYK Chemical. Antioxidants are divided into primary and secondary antioxidants, and the mixed use is more effective than the single use of the primary antioxidant or the secondary antioxidant.

[0017] According to some preferred embodiments of the present invention, the catalyst is bismorpholinyl diethyl ether.

[0018] According to some preferred implementation aspects of the present invention, the tackifying resin is one or more of ethylene-vinyl acetate copolymer, rosin resin, terpene resin, and thermoplastic polyurethane resin, preferably a mixture of terpene resin and thermoplastic polyurethane resin, with a mass ratio of 1.5-2.5: 1, preferably 2: 1. The mixture of terpene resin and thermoplastic polyurethane resin can increase the final bonding strength of the glue.

[0019] According to some preferred implementation aspects of the present invention, the viscosity of the reactive polyurethane hot melt adhesive for edge sealing at 140°C is 32000-46000mpa.s, the open time is 15-60S, the initial adhesive strength is 3.0-4.5MPa, the final strength after curing at 35°C is 6.3-7.2MPa, the final strength after curing at 0°C is 5.8-6.8MPa, and the final strength decrease ratio from curing at 35°C to curing at 0°C is 5.5%-14.5%. For the definition of initial adhesive strength and final strength, please refer to GB / T 7124-2008. Initial adhesive strength is the adhesive strength five minutes after application, and final strength is the adhesive strength after curing for 48h after application. The difference in final strength under curing conditions of 35°C and 0°C is not much, which proves that it can be used in winter. Initial adhesive strength can ensure no rebound, and final adhesive strength at 0°C can indicate good winter bonding.

[0020] Preferably, the reactive polyurethane hot melt adhesive for edge sealing has a viscosity of 45600 mpa.s at 140°C, an open time of 45 seconds, an initial adhesive strength of 3.9 MPa, a final strength of 7.2 MPa at 35°C, a final strength of 6.8 MPa at 0°C, and a final strength drop ratio of 5.56% from 35°C to 0°C. For the definition of initial adhesive strength and final strength, refer to GB / T7124-2008.

[0021] The present invention also provides a method for preparing the reactive polyurethane hot melt adhesive for edge sealing as described above, comprising the following steps:

[0022] The polyester polyol is heated until dissolved;

[0023] Raise the temperature to 145-155℃, add filler and tackifying resin, mix well, and evacuate;

[0024] Cool down to 100-110℃, turn off the vacuum, add diisocyanate, continue to evacuate, and maintain the temperature at 105-115℃;

[0025] Add a catalyst, raise the temperature to 130-140° C., maintain the vacuum degree below -0.098 MPa for 15-30 minutes, and obtain the reactive polyurethane hot melt adhesive for edge sealing.

[0026] Specifically, in some embodiments of the present invention, the method for preparing the reactive polyurethane hot melt adhesive for edge sealing comprises the following steps:

[0027] 1. Add polyester polyol to the reactor, turn on the heating, heat to 125-135°C, start stirring, and set the speed to 80 rpm;

[0028] 2. After the raw materials in the reactor are dissolved, the reactor is heated to 150°C, fillers and tackifying resins are added, the speed is set to 200 rpm, and the materials are observed to be uniform and free of particles. The vacuum pump is turned on to make the vacuum degree in the reactor below -0.098Mpa and maintained for 1.5-2.5h;

[0029] 3. Cool down to 100-110℃, turn off the vacuum, fill with nitrogen to equalize the pressure, and set the speed to 250 rpm. Add diisocyanate under nitrogen protection, continue to evacuate, maintain the temperature at 110±3℃, and maintain for 1.0-2.0h.

[0030] 4. Stop vacuuming, keep nitrogen pressure constant, keep the speed unchanged, add catalyst, and continue stirring under vacuum for 0.3-0.7h.

[0031] 5. Raise the temperature to 130-140℃, keep the vacuum degree below -0.098Mpa, set the speed to 100 rpm, 15-30min;

[0032] 6. Stop vacuuming, level out the nitrogen pressure, discharge the material, and obtain the reactive polyurethane hot melt adhesive for edge sealing.

[0033] The present invention also provides a use of the reactive polyurethane hot melt adhesive for edge sealing as described above in woodworking edge sealing.

[0034] Due to the adoption of the above technical scheme, compared with the prior art, the present invention is beneficial in that: the reactive polyurethane hot melt adhesive for edge sealing of the present invention adopts barium sulfate and hollow glass microspheres as fillers, and barium sulfate can improve the initial bonding strength while the melt viscosity is lower than that of calcium carbonate, and has low viscosity and better permeability, which is of great help to the bonding strength at low temperatures; and the hollow glass microspheres can improve the fluidity of the glue, prolong the open time, so that it can be better wetted in winter, so that the prepared reactive polyurethane hot melt adhesive for edge sealing does not rebound in summer, and still has good bonding strength in winter, and can be used in both winter and summer. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0036] In this embodiment, the preparation method of the reactive polyurethane hot melt adhesive for edge sealing specifically includes the following steps:

[0037] Step 1: Confirm that the vacuum pump can operate normally and the vacuum degree is below -0.098Mpa. The reactor is clean and free of impurities.

[0038] Step 2: Add polyester polyol, assemble the reactor, and confirm that the thermometer has been inserted into the material.

[0039] Step 3: Turn on the heating, raise the temperature to 130°C, start stirring and set the speed to 80 rpm to confirm that the raw materials in the reactor are dissolved.

[0040] Step 4: Keep the reactor temperature at 150°C, add filler and tackifying resin, set the speed to 200 rpm, observe that the material is uniform and free of particles (the appearance of the material can be transparent, milky white, or yellow), turn on the vacuum pump, and keep the vacuum degree in the reactor below -0.098 MPa for 2 hours.

[0041] Step 5: When the temperature drops to 105°C, turn off the vacuum, fill with nitrogen to equalize the pressure, and set the speed to 250 rpm.

[0042] Mix solid MDI-100 and liquid MDI-50 and heat them in an oven to melt. Make sure that the diisocyanate in the oven is clear and transparent without any white foreign matter. Melt the diisocyanate in advance, and the melted isocyanate will be more convenient for feeding; the melted isocyanate can be dispersed faster to avoid local agglomeration.

[0043] Step 6: Add diisocyanate under nitrogen protection, continue to evacuate, and maintain the temperature at 110±3°C. This process takes 1.5 hours.

[0044] Step 7: Stop vacuuming, keep nitrogen pressure constant, keep the rotation speed unchanged, add catalyst, and continue vacuum stirring for 0.5 h.

[0045] Step 8: Raise the temperature to 135°C while maintaining the vacuum degree below -0.098 MPa, set the rotation speed to 100 rpm, and maintain for 20 min.

[0046] Step 9: Stop vacuuming, balance the nitrogen pressure, and discharge the material.

[0047] Example 1

[0048] The method for preparing the reactive polyurethane hot melt adhesive for edge sealing of this embodiment specifically comprises the following steps:

[0049] Weigh 50 parts of hexamethylene adipate diol with a number average molecular weight of 8500, 15 parts of polyester polyol FA-2817 with a number average molecular weight of 2000, 40 parts of polyester polyol LH-9130 with a number average molecular weight of 3500, 0.06 parts of antioxidant 1010, 0.06 parts of antioxidant 126, and 0.08 parts of defoaming agent.

[0050] After the reactor was assembled, the temperature was raised to 130°C and stirring was started, with the speed set to 80 rpm.

[0051] After the material is dissolved, the temperature is raised to 150°C, the speed is 200 rpm, 35 parts of ethylene-vinyl acetate copolymer, 20 parts of 1250 mesh barium sulfate powder, and 2 parts of hollow glass microspheres are added, the vacuum pump is turned on to maintain the vacuum degree below -0.098 MPa, and the air is evacuated for 2 hours.

[0052] Cool down to 105°C, stop vacuuming, add 18 parts of MDI-100 and 6 parts of MDI-50 under nitrogen protection, set the speed to 250 rpm, maintain the temperature at 110±3°C, stir for 1.5 hours, add 0.1 parts of catalyst dimorpholinyl diethyl ether, and start vacuuming for 30 minutes.

[0053] Heat to 135 degrees, adjust the speed to 100 rpm, and maintain for 20 minutes. Stop vacuuming, seal the material and store it.

[0054] The product has a viscosity of 33500mpa.s at 140°C, a test open time of approximately 1min, an initial adhesive strength of approximately 3.7MPa, a final strength of 6.4MPa after curing at 35°C, and a final strength of 5.5MPa after curing at 0°C.

[0055] Example 2

[0056] The method for preparing the reactive polyurethane hot melt adhesive for edge sealing of this embodiment specifically comprises the following steps:

[0057] 50 parts of hexamethylene adipate diol with a weighed number average molecular weight of 8500, 18 parts of polyester polyol Dynacoll 7250 with a weighed number average molecular weight of 5500, 40 parts of polyester polyol LH-9130 with a weighed number average molecular weight of 3500, 0.14 parts of antioxidant 1010, and 0.08 parts of defoaming agent were weighed.

[0058] After the reactor was assembled, the temperature was raised to 130°C and stirring was started, with the speed set to 80 rpm.

[0059] After the material is dissolved, the temperature is raised to 150°C and the speed is 200 rpm. 40 parts of rosin pentaerythritol ester, 10 parts of thermoplastic polyurethane elastomer, 22 parts of 1250 mesh barium sulfate powder, and 2.2 parts of hollow glass microspheres are added. The vacuum pump is turned on to maintain the vacuum degree below -0.098 MPa and evacuate for 2 hours.

[0060] Cool down to 105°C, stop vacuuming, add 18 parts of MDI-100 and 6 parts of MDI-50 under nitrogen protection, set the speed to 250 rpm, maintain the temperature at 110±3°C, stir for 1.5 hours, add 0.1 parts of catalyst dimorpholinyl diethyl ether, and start vacuuming for 30 minutes.

[0061] Heat to 135 degrees, adjust the speed to 100 rpm, and maintain for 20 minutes. Stop vacuuming, seal the material and store it.

[0062] The product has a viscosity of 32800mpa.s at 140°C, a test open time of approximately 1min, an initial adhesive strength of approximately 3.1MPa, a final strength after curing at 35°C of 6.8MPa, and a final strength after curing at 0°C of 5.9MPa.

[0063] Example 3

[0064] The method for preparing the reactive polyurethane hot melt adhesive for edge sealing of this embodiment specifically comprises the following steps:

[0065] 45 parts of hexamethylene adipate diol with a weighed number average molecular weight of 3500, 15 parts of Dynacoll 7250 with a weighed number average molecular weight of 5500, 45 parts of polyester polyol LH-9150 with a weighed number average molecular weight of 2600, 0.06 parts of antioxidant AO-80, 0.06 parts of 126, and 0.08 parts of defoaming agent were weighed.

[0066] After the reactor was assembled, the temperature was raised to 130°C and stirring was started, with the speed set to 80 rpm.

[0067] After the material is dissolved, the temperature is raised to 150°C, the speed is 200 rpm, 35 parts of terpene resin, 25 parts of thermoplastic polyurethane elastomer, 18 parts of 1250 mesh barium sulfate powder, and 1.8 parts of hollow glass microspheres are added, the vacuum pump is turned on to maintain the vacuum degree below -0.098 MPa, and the air is evacuated for 2 hours.

[0068] Cool down to 105°C, stop vacuuming, add 18 parts of MDI-100 and 6 parts of MDI-50 under nitrogen protection, set the speed to 250 rpm, maintain the temperature at 110±3°C, stir for 1.5 hours, add 0.1 parts of catalyst dimorpholinyl diethyl ether, and start vacuuming for 30 minutes.

[0069] Heat to 135 degrees, adjust the speed to 100 rpm, and maintain for 20 minutes. Stop vacuuming, seal the material and store it.

[0070] The product has a viscosity of 45600mpa.s at 140°C, a test open time of approximately 45s, an initial adhesive strength of approximately 4.5MPa, a final strength of 7.2MPa after curing at 35°C, and a final strength of 6.8MPa after curing at 0°C.

[0071] Example 4

[0072] The method for preparing the reactive polyurethane hot melt adhesive for edge sealing of this embodiment specifically comprises the following steps:

[0073] 30 parts of hexanediol dodecanedioate with a number average molecular weight of 3500, 35 parts of Dynacoll 7250 with a number average molecular weight of 5500, 40 parts of polyester polyol LH-9130 with a number average molecular weight of 3500, 0.14 parts of antioxidant AO-80, and 0.08 parts of defoaming agent were weighed.

[0074] After the reactor was assembled, the temperature was raised to 130°C and stirring was started, with the speed set to 80 rpm.

[0075] After the material is dissolved, the temperature is raised to 150°C, the speed is 200 rpm, 40 parts of ethylene-vinyl acetate copolymer, 19 parts of 1250 mesh barium sulfate powder, and 1.9 parts of hollow glass microspheres are added, and the vacuum pump is turned on to maintain the vacuum degree below -0.098 MPa, and the air is evacuated for 2 hours.

[0076] Cool down to 105°C, stop vacuuming, add 18 parts of MDI-100 and 6 parts of MDI-50 under nitrogen protection, set the speed to 250 rpm, maintain the temperature at 110±3°C, stir for 1.5 hours, add 0.1 parts of catalyst dimorpholinyl diethyl ether, and start vacuuming for 30 minutes.

[0077] Heat to 135 degrees, adjust the speed to 100 rpm, and maintain for 20 minutes. Stop vacuuming, seal the material and store it.

[0078] The product has a viscosity of 35500mpa.s at 140°C, a test open time of approximately 15s, an initial adhesive strength of approximately 4.0MPa, a final strength of 6.4MPa after curing at 35°C, and a final strength of 5.5MPa after curing at 0°C.

[0079] Example 5

[0080] The method for preparing the reactive polyurethane hot melt adhesive for edge sealing of this embodiment specifically comprises the following steps:

[0081] 45 parts of hexanediol dodecanedioate diol with a weighed number average molecular weight of 3500, 20 parts of polyester polyol CMB-54 with a weighed number average molecular weight of 2000, 45 parts of polyester polyol CMA-244 with a weighed number average molecular weight of 2000, 0.14 parts of antioxidant 626, and 0.08 parts of defoaming agent were weighed.

[0082] After the reactor was assembled, the temperature was raised to 130°C and stirring was started, with the speed set to 80 rpm.

[0083] After the material is dissolved, the temperature is raised to 150°C, the speed is 200 rpm, 40 parts of terpene resin, 25 parts of 1250 mesh barium sulfate powder, and 2.5 parts of hollow glass microspheres are added, and the vacuum pump is turned on to maintain the vacuum degree below -0.098 MPa, and the air is evacuated for 2 hours.

[0084] Cool down to 105°C, stop vacuuming, add 18 parts of MDI-100 and 6 parts of MDI-50 under nitrogen protection, set the speed to 250 rpm, maintain the temperature at 110±3°C, stir for 1.5 hours, add 0.1 parts of catalyst dimorpholinyl diethyl ether, and start vacuuming for 30 minutes.

[0085] Heat to 135 degrees, adjust the speed to 100 rpm, and maintain for 20 minutes. Stop vacuuming, seal the material and store it.

[0086] The product has a viscosity of 32900mpa.s at 140°C, a test open time of approximately 50s, an initial adhesive strength of approximately 3.0MPa, a final strength of 6.3MPa after curing at 35°C, and a final strength of 5.7MPa after curing at 0°C.

[0087] Comparative Example 1

[0088] The difference between this comparative example and Example 3 is that the filler in this comparative example is entirely 1250 mesh barium sulfate powder, and does not contain hollow glass microspheres. The remaining steps and parameters are basically the same as those in Example 3.

[0089] The product has a viscosity of 37000mpa.s at 140°C, a test open time of approximately 30s, an initial adhesive strength of approximately 3.5MPa, a final strength of 6.0MPa after curing at 35°C, and a final strength of 5.3MPa after curing at 0°C.

[0090] Since the product does not contain hollow glass microspheres, its melt viscosity becomes smaller, and its initial adhesion strength and final strength become weaker.

[0091] Comparative Example 2

[0092] The difference between this comparative example and Example 3 is that the diisocyanate in this comparative example is entirely MDI-100 and does not contain MDI-50. The remaining steps and parameters are basically the same as those in Example 3.

[0093] The product has a viscosity of 49000mpa.s at 140°C, a test open time of approximately 40s, an initial adhesive strength of approximately 4.4MPa, a final strength of 7.1MPa at 35°C, and a final strength of 5.1MPa at 0°C.

[0094] Since it does not contain MDI-50, the product's melt viscosity increases, the open time is shortened, and the bonding strength becomes weaker at low temperatures.

[0095] Comparative Example 3

[0096] The difference between this comparative example and Example 3 is that the mass ratio of barium sulfate to hollow glass microspheres in the filler of this comparative example is 5:1. The remaining steps and parameters are basically the same as those in Example 3.

[0097] The product has a viscosity of 63000mpa.s at 140°C, a test open time of about 55s, an initial adhesive strength of about 4.1MPa, a final strength of 5.2MPa at 35°C, and a final strength of 3.5MPa at 0°C.

[0098] Due to the excessive addition of hollow glass microspheres, the melt viscosity of the product increases, the final bonding strength decreases and the curing performance at low temperatures deteriorates.

[0099] Comparative Example 4

[0100] The difference between this comparative example and Example 3 is that the filler in this comparative example is 1250 mesh calcium carbonate. The remaining steps and parameters are basically the same as those in Example 3.

[0101] The product has a viscosity of 45000mpa.s at 140°C, a test open time of approximately 38s, an initial adhesive strength of approximately 3.4MPa, a final strength of 6.5MPa after curing at 35°C, and a final strength of 5.0MPa after curing at 0°C.

[0102] Due to the absence of barium sulfate and hollow glass microspheres, the product's initial bonding strength becomes weaker, the final bonding strength decreases, and the curing performance at low temperatures becomes worse.

[0103] Comparative Example 5

[0104] The difference between this comparative example and Example 3 is that the mass ratio of MDI-100 to MDI-50 in this comparative example is 1:1. The remaining steps and parameters are basically the same as those in Example 3.

[0105] The product has a viscosity of 45000mpa.s at 140°C, a test open time of about 65s, an initial adhesive strength of about 3.6MPa, a final strength of 5.9MPa at 35°C, and a final strength of 5.5MPa at 0°C.

[0106] Comparative Example 6

[0107] The difference between this comparative example and Example 3 is that the mass ratio of MDI-100 to MDI-50 in this comparative example is 5:1. The remaining steps and parameters are basically the same as those in Example 3.

[0108] The product has a viscosity of 49000mpa.s at 140°C, a test open time of approximately 45s, an initial adhesive strength of approximately 4.1MPa, a final strength of 6.5MPa at 35°C, and a final strength of 4.8MPa at 0°C.

[0109] Tests and Results

[0110] Referring to GB / T 7124-2008, the hot melt adhesive products prepared in the examples and comparative examples were subjected to relevant tests, and the test results are shown in Table 1:

[0111] Table 1 Test results

[0112]

[0113]

[0114] The final strength difference ratio in Table 1 is the ratio of the absolute value of the difference between the final strength cured at 35°C and the final strength cured at 0°C to the final strength cured at 35°C.

[0115] The results in Table 1 show that the hot melt adhesive prepared in the embodiment has high final strength when cured at 35°C and 0°C with little change, can achieve no rebound in summer, and still has good bonding strength in winter, and can be used in both winter and summer.

[0116] The existing edge sealing adhesive is prone to rebound in high temperatures in summer, and the edge sealing strip bonding strength is not high in low temperatures in winter. The present application improves the rebound problem in summer by increasing the initial bonding strength of PUR, and improves the bonding strength in winter by improving the wettability of PUR. Specifically, the present invention uses barium sulfate and hollow glass microspheres as fillers. The advantage of barium sulfate is that it improves the initial bonding strength while the melt viscosity is lower than that of calcium carbonate, and the hollow glass microspheres can improve the fluidity of the glue, so that it can be better wetted in winter; so that the final reactive polyurethane hot melt adhesive for edge sealing has improved open time, increased initial bonding strength, and enhanced final bonding strength.

[0117] The above embodiments prepared by the method of the present invention are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A reactive polyurethane hot melt adhesive for edge sealing, characterized in that: The reactive polyurethane hot melt adhesive for edge sealing comprises the following raw material components by weight: The filler comprises barium sulfate and hollow glass microspheres, and the mass ratio of the barium sulfate to the hollow glass microspheres is 9-11:

1.

2. The reactive polyurethane hot melt adhesive for edge sealing according to claim 1, characterized in that: The barium sulfate has a mesh size of 1000-1500 meshes, a water content of less than 0.1%, an oil absorption of less than 10 mL / 100 g, and a whiteness of 90-95.

3. The reactive polyurethane hot melt adhesive for edge sealing according to claim 1, characterized in that: The true density of the hollow glass microspheres is 0.4-0.44, the bulk density is 0.21-0.24, and the particle size is 20-30 μm.

4. The reactive polyurethane hot melt adhesive for edge sealing according to claim 1, characterized in that: The diisocyanate includes MDI-100 and MDI-50, and the mass ratio of the two is 2-4:

1.

5. The reactive polyurethane hot melt adhesive for edge sealing according to claim 1, characterized in that: The auxiliary agent is an antioxidant and / or a defoaming agent, wherein the antioxidant is one or more selected from 1010, 126 and AO-80; the defoaming agent is BYK-A535 and / or BYK-1790.

6. The reactive polyurethane hot melt adhesive for edge sealing according to claim 1, characterized in that: The catalyst is bismorpholinyl diethyl ether.

7. The reactive polyurethane hot melt adhesive for edge sealing according to claim 1, characterized in that: The tackifying resin is one or more of ethylene-vinyl acetate copolymer, rosin resin, terpene resin, and thermoplastic polyurethane resin.

8. The reactive polyurethane hot melt adhesive for edge sealing according to any one of claims 1 to 7, characterized in that: The reactive polyurethane hot melt adhesive for edge sealing has a viscosity of 32000-46000 mpa.s at 140°C, an open time of 15-60s, an initial adhesive strength of 3.0-4.5 MPa, a final strength of 6.3-7.2 MPa after curing at 35°C, a final strength of 5.8-6.8 MPa after curing at 0°C, and a final strength reduction ratio of 5.5%-14.5% from curing at 35°C to curing at 0°C.

9. A method for preparing the reactive polyurethane hot melt adhesive for edge sealing according to any one of claims 1 to 8, characterized in that: The steps include: The polyester polyol is heated until dissolved; Raise the temperature to 145-155℃, add filler and tackifying resin, mix well, and evacuate; Cool down to 100-110℃, turn off the vacuum, add diisocyanate, continue to evacuate, and maintain the temperature at 105-115℃; Add a catalyst, raise the temperature to 130-140° C., maintain the vacuum degree below -0.098 MPa for 15-30 minutes, and obtain the reactive polyurethane hot melt adhesive for edge sealing.

10. Use of the reactive polyurethane hot melt adhesive for edge banding as claimed in any one of claims 1 to 8 in woodworking edge banding.

Images