CN104531002B - A kind of magnetic PUR and its preparation and application - Google Patents

Abstract

Aiming at the current lack of related technology that magnetic nano powder can promote the melting of hot-melt adhesive, the present invention provides a magnetic hot-melt adhesive and its preparation and use methods, which belong to the field of adhesives. The magnetic hot melt adhesive raw material is composed of parts by weight: 10-60 parts of thermoplastic polymer, 25-55 parts of tackifier, 2-20 parts of plasticizer, 3-15 parts of viscosity regulator, 0.1-4.5 parts of antioxidant , 5‑30 parts magnetic ferrite powder. The magnetothermal melt adhesive disperses nano-magnetic ferrite powder with magnetocaloric properties evenly in the hot-melt adhesive. In the alternating magnetic field, the heat generated by the nano-ferrite particles spreads rapidly to the surroundings in a radial manner, prompting the neighboring hot-melt adhesive to Molecules are heated quickly and can be quickly bonded within a few seconds, so it has the advantages of uniform coating and high bonding strength. It does not need to be equipped with heating equipment, nor does it need to preheat the melt glue. It only needs a small alternating magnetic field generator. It is easy to operate and suitable for continuous, automated and high-speed operations. The cured hot melt adhesive can be easily re-separated by heating in an alternating magnetic field.

Description

A kind of magnetic hot melt adhesive and its preparation and use method

technical field

The invention belongs to the field of adhesives, and in particular relates to a magnetothermal melt adhesive and a preparation and use method thereof.

Background technique

Hot melt adhesives have the advantages of fast curing, no pollution, and convenient preparation, and are widely used in mechanized packaging, furniture making, shoemaking, automobiles, perfect binding, electronic components and daily necessities bonding. At present, hot melt adhesives with fillers occupy the vast majority of the market due to their low price, but due to their long melting time and high viscosity after melting, they have poor wettability and are difficult to coat evenly, so they are not suitable for large areas. Coating and bonding, and the heat resistance of hot melt adhesive is not high, so it can only be used for products with low process requirements. Although there are many studies on the effect of adding fillers on the properties of hot melt adhesives in China, most of the research on fillers is still in the reinforcement stage of fillers, and the special properties of some fillers and the resulting adhesive properties Variations have not been studied extensively. At present, there is no related technology of magnetic nano powder to promote the melting of hot melt adhesive at home and abroad.

When using hot-melt adhesive, it needs to be equipped with special equipment for melting and sizing, such as hot-melt adhesive machine, hot-melt adhesive heating tube, hot-melt adhesive gun, etc., which is inconvenient to use, thus limiting the use and promotion of hot-melt adhesive . For the separation of the cured hot melt adhesive layer, there are two separation methods: heating method and solvent dissolution method. The solvent dissolution method can cause environmental pollution, and heating separation is not allowed or even impossible in many occasions, such as civil engineering and construction. Therefore, there is an urgent demand in the market to develop hot melt adhesives with low cost, fast melting, uniform coating, high bonding strength and easy separation.

Contents of the invention

The purpose of the present invention is to overcome the defects in the prior art, and provide a magnetic hot melt adhesive and its preparation and use method. The magnetic hot-melt adhesive proposed by the present invention uses ferrite nanoparticles prepared by polyol method as filler, and its surface is modified with a coupling agent so that it is evenly dispersed in the hot-melt adhesive, and the magnetic particles have magnetic properties. The thermal effect makes it convert magnetic energy into thermal energy in an alternating magnetic field, and the heat generated by nano-ferrite particles spreads rapidly to the surroundings in a radial manner, which promotes uniform heating of adjacent molecules of the hot melt adhesive, shortens the melting time, and improves the bonding strength. The product has the advantages of low cost, no pollution, fast and simple operation, uniform coating, high bonding strength and easy re-separation. The preparation and use method is simple, convenient and easy to implement.

In order to achieve the above object, one of the technical solutions of the present invention is as follows:

A magnetic hot-melt adhesive, according to the number of parts by weight: 10-60 parts of thermoplastic polymer, 25-55 parts of tackifier, 2-20 parts of plasticizer, 3-15 parts of viscosity regulator, anti- The oxygen agent is 0.1-4.5 parts, and the nano-magnetic ferrite is 5-30 parts;

A good number of parts by mass is: 25-45 parts for thermoplastic polymers, 25-45 parts for tackifiers, 2-10 parts for plasticizers, 6-14 parts for viscosity modifiers, and 0.3-45 parts for antioxidants. 2.5 parts, nano-magnetic ferrite is 6-25 parts;

The best mass parts are: 27-35 parts for thermoplastic polymers, 26-40 parts for tackifiers, 3-6 parts for plasticizers, 9-13 parts for viscosity modifiers, and 0.5-30 parts for antioxidants. 1.8 parts, nano-magnetic ferrite is 8-20 parts;

Wherein, the thermoplastic polymer is ethylene-vinyl acetate copolymer (EVA), polyamide resin, polyester resin, polyurethane resin, polypropylene resin, polyvinyl acetate resin, styrene-diene-styrene ternary Block copolymer SDS (styrene-butadiene-styrene triblock copolymer SBS, styrene-isoprene-styrene triblock copolymer SIS), polyvinyl alcohol, polyethylene, polyvinyl alcohol One or a mixture of vinyl chloride, ethylene-ethyl acrylate copolymer (EEA), ethylene-acrylic acid copolymer (EAA), and diallyl phthalate (DAP);

The tackifier is one or a mixture of rosin and derivatives thereof, terpene resins, petroleum resins, phenolic resins, and coumarone resins;

The plasticizer is one or a mixture of dioctyl phthalate, dibutyl phthalate, tricresyl phosphate, naphthenic oil, polybutadiene;

The viscosity regulator is one or a mixture of paraffin wax, Sasol synthetic wax, microcrystalline wax, ozokerite wax, and low molecular polyethylene wax;

The antioxidant is 2,6-tert-butyl p-cresol (BHT), antioxidant 1010, 4,4-mercaptobis(6-tert-butylxylenol) (RC), thiodipropionic acid One or a mixture of esters;

The nano-magnetic ferrite is nickel-zinc, manganese-zinc, cobalt-zinc ferrite magnetic nanoparticles prepared by the polyol method, and the preferred nano-magnetic ferrite is manganese-zinc ferrite; the magnetic content of the ferrite is It is 30-70wt%, and the average particle diameter of ferrite is 6nm-80nm.

The second technical scheme of the present invention is as follows:

A preparation method of magnetic hot melt adhesive, comprising the following steps:

1) Put the tackifier, antioxidant, and viscosity modifier into the container according to the dosage of the above formula, heat it to above 60°C, stir evenly, and melt the mixture;

2) After the mixture prepared in step 1) is completely melted, add the thermoplastic polymer and plasticizer in the formulated amount respectively, and stir evenly at 150-180°C;

3) After the mixture prepared in step 2) is completely melted and mixed, add the surface-modified magnetic nano-ferrite powder of the formula amount, and stir evenly;

Among them, the method for surface modification of magnetic nano-ferrite powder is as follows: Weigh an appropriate amount of nano-powder, add silane coupling agent KH-550 for ultrasonic treatment for 2 hours, and then vacuum dry to obtain surface-modified magnetic nano-ferrite powder. body powder;

4) Stop heating the mixture prepared in step 3), make its temperature drop to ≤130°C, and filter through a 200-300 mesh filter screen;

5) Put the filtered compound in step 4) in an extruder, extrude it at 100-160°C, and then undergo cooling, pelletizing, drying and other processes to obtain the magnetic hot-melt adhesive.

The third technical scheme of the present invention is as follows:

A kind of using method of magnetothermal melt adhesive, can choose following method 1) or 2):

1) When the magnetic hot melt adhesive is used for pasting, spread the magnetic hot melt adhesive on the surface to be bonded, add an alternating magnetic field to melt it, stick the two bonding surfaces together, and wait for the magnetic hot melt to melt. After the gel is solidified;

2) When the solidified magnetothermal melt adhesive layer is separated, an alternating magnetic field is added on the bonding surface to remelt the magnetothermal melt adhesive to achieve re-separation;

The preferable alternating magnetic field intensity is 5-15kA/m, the alternating heating current is 10-100A, and the magnetic field frequency is 100-180kHz.

Compared with the prior art, the present invention has the advantages of:

1. Uniform coating: due to the uniform distribution of magnetic nano-ferrite in the hot melt adhesive, the heat generated by the nano-ferrite particles in the alternating magnetic field rapidly extends to the surroundings in a radial manner, which promotes the uniform heating of the adjacent molecules of the hot melt adhesive. Magnetic hot melt adhesives can overcome the heating method of traditional hot melt adhesives from the surface to the inside, and realize uniform heating within the molecule, thus avoiding the generation of temperature gradients, thereby ensuring that the hot melt adhesives are heated equally in all directions, so that the hot melt adhesives can be evenly coated.

2. Fast bonding: the alternating magnetic field can directly heat the solid melt adhesive without preheating and heating the surface to be bonded, and can bond quickly within a few seconds, suitable for continuous, automated high-speed operations, and low cost.

3. Re-separation: If the hot melt adhesive coated on the adherend cannot be bonded due to cooling and solidification or the bonding effect is not satisfactory, it can be re-placed in an alternating magnetic field and heated for re-separation.

4. High bonding strength: Adding ferrite fillers to hot melt adhesives can reduce shrinkage and improve bonding strength and heat resistance.

5. Easy to operate: no heating equipment such as hot-melt glue machine, hot-melt glue heating tube, hand-held hot-melt glue gun and hot-melt glue coating machine are needed, and there is no need to preheat the melt glue, only a small alternating magnetic field is required The device can make it melt quickly.

Description of drawings

Fig. 1 is the transmission electron microscope figure of the manganese zinc ferrite that the present invention selects;

Fig. 2 is a hysteresis loop diagram of the manganese zinc ferrite selected in the present invention.

detailed description

The materials used in the present invention are commercially available unless otherwise specified.

The preparation method of nickel-zinc, manganese-zinc and cobalt-zinc ferrite: adding iron acetylacetonate, zinc acetylacetonate and nickel acetylacetonate or manganese acetylacetonate or cobalt acetylacetonate at a molar ratio of 4:1:1 to ethylene glycol , heated in an Ar protective atmosphere, and kept at 80-90°C for 10-30 minutes; then slowly raised to 170-200°C and held for 2-5 minutes, then rapidly raised to 255-265°C, refluxed for 50-90 minutes, and finally cooled naturally to room temperature Add absolute ethanol to the reaction solution to obtain a black reaction solution; centrifuge the solution, wash the precipitate repeatedly with absolute ethanol for 3 to 5 times, and finally dry the washed black precipitate in vacuum to obtain Ni _0.5 Zn _0.5 Fe ₂ O _4. Mn _0.5 Zn _0.5 Fe ₂ O ₄ or Co _0.5 Zn _0.5 Fe ₂ O ₄ nano ferrite powder.

The method for surface modification of magnetic nano-ferrite powder is as follows: Weighing an appropriate amount of nano-powder, adding silane coupling agent KH-550 for ultrasonic treatment for 2 hours, and then vacuum-drying to obtain surface-modified magnetic nano-ferrite powder.

Example 1

25 kg of EVA, 22.5 kg of rosin, 4.5 kg of polybutadiene, 5 kg of Sasol synthetic wax, 0.5 kg of antioxidant 1010, and surface-modified magnetic manganese zinc ferrite nano 8 kilograms of powder; the softening point of the Sasol synthetic wax is between 110° C. and 120° C.; the plasticizer is low-molecular polybutadiene with a molecular weight of 2300.

Put rosin, antioxidant 1010, and Sasol synthetic wax into the container according to the formula dosage, and heat it to above 60°C, stir evenly to melt the above mixture; after the materials are completely melted, add the formula amount of EVA and polybutane ene, stir evenly at 150-180°C; after complete melting and mixing, add the surface-modified magnetic manganese-zinc-ferrite nano-powder in the formula amount, and stir evenly; stop heating the mixed molten material to make the temperature Lower to no higher than 130°C, then filter the above molten material through a 200-mesh filter; take the filtered molten material and put it in an extruder, extrude at 100-160°C, and then cool, pelletize, and dry After drying and other processes, the magnetic hot-melt adhesive can be obtained.

When using the magnetic hot melt adhesive, spread it on the surface to be bonded, add an alternating magnetic field to make it melt rapidly within 1 minute, then stick the two bonding surfaces together, and wait for the magnetic After the hot melt glue is solidified, the magnetic field strength is 8kA/m, the alternating heating current is 30A, and the magnetic field frequency is 130kHz.

If it is necessary to separate the solidified hot-melt adhesive layer, add an alternating magnetic field on the bonded surface to re-melt the magnetic hot-melt adhesive to achieve re-separation. The magnetic field strength is 10kA/m, and the alternating heating current is 35A with a magnetic field frequency of 140kHz.

The test results are shown in Table 1.

Example 2

52 kg of EEA, 41.2 kg of coumarone resin, 3.6 kg of dibutyl phthalate, 11 kg of microcrystalline wax, 1.2 kg of thiodipropionate, and surface-modified 20 kg of magnetic nickel-zinc ferrite nanopowder; the softening point of the microcrystalline wax is between 60°C and 90°C.

Put the coumarone resin, thiodipropionate, and microcrystalline wax into the container according to the amount of the formula, and heat it to above 60°C, stir evenly to melt the above mixture; after the materials are completely melted, add the amount of the formula respectively EEA, dibutyl phthalate, stir evenly at 150-180°C; after complete melting and mixing, add the surface-modified magnetic nickel-zinc ferrite nano-powder in the formulated amount, and stir evenly; mix the Stop heating the molten material to lower its temperature to no higher than 130°C, and then filter the above molten material through a 300-mesh filter; take the filtered molten material and place it in an extruder, and extrude it at 100-160°C. After cooling, pelletizing, drying and other processes, the magnetic hot melt adhesive is obtained.

When using the magnetic hot melt adhesive, spread it on the surface to be bonded, add an alternating magnetic field to make it melt rapidly within 1 minute, then stick the two bonding surfaces together, and wait for the magnetic After the hot melt glue is solidified, the magnetic field strength is 12kA/m, the alternating heating current is 40A, and the magnetic field frequency is 160kHz.

If it is necessary to separate the solidified hot-melt adhesive layer, add an alternating magnetic field on the bonded surface to re-melt the magnetic hot-melt adhesive to achieve re-separation. The magnetic field strength is 14kA/m, and the alternating heating current is 45A with a magnetic field frequency of 170kHz.

The test results are shown in Table 1.

Example 3

26.5 kg of EVA, 20.3 kg of rosin, 1.9 kg of dibutyl phthalate, 5 kg of paraffin, 0.8 kg of thiodipropionate, and surface-modified magnetic cobalt zinc iron oxide are required to make 69.5 kg of magnetic hot melt adhesive 15 kg of body nano powder; the softening point of the paraffin wax is between 55°C and 85°C.

Put rosin, thiodipropionate, and paraffin into the container according to the formula dosage, and heat it to above 60°C, stir evenly to melt the above mixture; after the materials are completely melted, add the formula amount of EVA, phthalate For dibutyl formate, stir evenly at 150-180°C; after complete melting and mixing, add the surface-modified magnetic cobalt-zinc ferrite nano-powder in the formulated amount, and stir evenly; stop heating the mixed molten material, Lower the temperature to no higher than 130°C, and then filter the above molten material through a 200-mesh filter; take the filtered molten material and place it in an extruder, extrude it at 100-160°C, and then cool and cut Granulation, drying and other processes to obtain magnetic hot melt adhesive.

When using the magnetic hot melt adhesive, spread it on the surface to be bonded, add an alternating magnetic field to make it melt rapidly within 1 minute, then stick the two bonding surfaces together, and wait for the magnetic After the hot melt glue is solidified, the magnetic field strength is 5kA/m, the alternating heating current is 10A, and the magnetic field frequency is 100kHz.

If it is necessary to separate the solidified hot-melt adhesive layer, add an alternating magnetic field on the bonded surface to re-melt the magnetic hot-melt adhesive to achieve re-separation. The magnetic field strength is 12kA/m, and the alternating heating current is 40A, the magnetic field frequency is 160kHz.

The test results are shown in Table 1.

Example 4

15.3 kg of polypropylene resin, 14.1 kg of coumarone resin, 0.8 kg of naphthenic oil, 2.7 kg of low molecular weight polyethylene wax, 0.4 kg of 2,6-tert-butyl p-cresol, and 6.6 kg of modified magnetic manganese zinc ferrite nanopowder; the softening point of the low molecular weight polyethylene wax is between 90°C and 110°C.

Put coumarone resin, 2,6-tert-butyl-p-cresol, and low-molecular-weight polyethylene wax into a container according to the formula dosage, and heat to above 60°C, stir evenly to melt the above mixture; after the materials are completely melted , respectively add the polypropylene resin and naphthenic oil in the formulated amount, and stir evenly at 150-180° C.; after completely melting and mixing, add the surface-modified magnetic manganese zinc ferrite nano powder in the formulated amount, and stir evenly; Stop heating the mixed molten material to lower its temperature to no higher than 130°C, then filter the above molten material through a 200-mesh filter, put the filtered molten material in an extruder, and extrude at 100-160°C out of molding, and then through cooling, dicing, drying and other processes to obtain magnetic hot melt adhesive.

When using the magnetic hot melt adhesive, spread it on the surface to be bonded, add an alternating magnetic field to make it melt rapidly within 1 minute, then stick the two bonding surfaces together, and wait for the magnetic After the hot melt glue is solidified, the magnetic field strength is 7kA/m, the alternating heating current is 25A, and the magnetic field frequency is 120kHz.

If it is necessary to separate the solidified hot-melt adhesive layer, add an alternating magnetic field on the bonded surface to re-melt the magnetic hot-melt adhesive to achieve re-separation. The magnetic field strength is 15kA/m, and the alternating heating current is 100A, the magnetic field frequency is 180kHz.

The test results are shown in Table 1.

Table 1 Hot melt adhesive performance test data

Example 5

To make 184.5 kg of magnetic hot melt adhesive, 20 kg of SBS, 20 kg of SIS, 20 kg of DAP, 35 kg of terpene resin, 20 g of hydrogenated rosin, 14 kg of dioctyl phthalate, and dibutyl phthalate are required 6 kilograms, 15 kilograms of ceresine wax, 4.5 kilograms of 4,4-mercapto bis(6-tert-butylxylenol), 30 kilograms of magnetic manganese zinc ferrite nanopowder after surface modification; Described ceresine wax softening point Between 62°C and 75°C.

Example 6

To make 45.1 kg of magnetic hot-melt adhesive, 5 kg of polyethylene, 5 kg of EAA, 25 kg of petroleum resin, 2 kg of tricresyl phosphate, 3 kg of paraffin, 0.1 kg of antioxidant 1010, and surface-modified magnetic manganese-zinc-iron 5 kg of oxygen nano powder; the softening point of the paraffin is between 55°C and 85°C.

Example 7

To make magnetic hot melt adhesive, 27-35 kg of EVA, 26-40 kg of terpene resin, 3-6 kg of dioctyl phthalate, 9-13 kg of Sasol synthetic wax, 4,4-mercaptobis( 0.5-1.8 kg of 6-tert-butylbiscresol) and 8-20 kg of surface-modified magnetic manganese zinc ferrite nanopowder; the softening point of the Sasol synthetic wax is between 110°C and 120°C.

Example 8

To make magnetic hot melt adhesive, 27-35 kg of polyamide resin, 26-40 kg of rosin, 3-6 kg of dibutyl phthalate, 9-13 kg of paraffin wax, 0.5 kg of 2,6-tert-butyl p-cresol - 1.8 kg, 8-20 kg of surface-modified magnetic nickel zinc ferrite nanopowder; the softening point of the paraffin wax is between 55°C and 85°C.

Example 9

To make magnetic hot melt adhesive, polyester resin 27-35 kg, water white rosin 26-40 kg, polybutadiene 3-6 kg, microcrystalline wax 9-13 kg, antioxidant 1010 0.5-1.8 kg, surface 8-20 kg of modified magnetic cobalt-zinc ferrite nanopowder; the softening point of the microcrystalline wax is between 60°C and 90°C; the plasticizer is low-molecular polybutadiene with a molecular weight of 2300 .

Example 10

To make magnetic hot melt adhesive, 27-35 kg of polyurethane resin, 26-40 kg of coumarone resin, 3-6 kg of naphthenic oil, 9-13 kg of low molecular weight polyethylene wax, and 0.5-1.8 kg of thiodipropionate are required 8-20 kg of surface-modified magnetic manganese-zinc-ferrite nanopowder; the softening point of the low-molecular polyethylene wax is between 90°C and 110°C.

Example 11

To make magnetic hot melt adhesive, 27-35 kg of polypropylene resin, 26-40 kg of phenolic resin, 3-6 kg of polybutadiene, 9-13 kg of Sasol synthetic wax, 0.5-1.8 kg of antioxidant 1010, surface 8-20 kg of modified magnetic manganese zinc ferrite nanopowder; the softening point of the Sasol synthetic wax is between 110°C and 120°C; alkene.

Example 12

To make magnetic hot melt adhesive, 27-35 kg of polyvinyl acetate resin, 26-40 kg of petroleum resin, 3-6 kg of tricresyl phosphate, 9-13 kg of ozokerite, 0.5-1.8 kg of antioxidant 1010, surface 8-20 kg of modified magnetic cobalt-zinc ferrite nanopowder; the softening point of the ozokerite is between 62°C and 75°C.

Example 13

To make magnetic hot melt adhesive, 27-35 kg of SDS, 26-40 kg of rosin, 3-6 kg of polybutadiene, 9-13 kg of Sasol synthetic wax, 10100.5-1.8 kg of antioxidant, and surface modified 8-20 kg of magnetic manganese zinc ferrite nano powder; the softening point of the Sasol synthetic wax is between 110 DEG C and 120 DEG C; the plasticizer is low-molecular polybutadiene with a molecular weight of 2300.

Example 14

To make magnetic hot melt adhesive, 27-35 kg of polyvinyl alcohol, 26-40 kg of hydrogenated rosin, 3-6 kg of polybutadiene, 9-13 kg of microcrystalline wax, 0.5-1.8 kg of BHT, and surface modified 8-20 kg of magnetic manganese zinc ferrite nano powder; the softening point of the microcrystalline wax is between 60 DEG C and 90 DEG C; the plasticizer is low-molecular polybutadiene with a molecular weight of 2300.

Example 15

To make magnetic hot melt adhesive, 27-35 kg of polyethylene, 26-40 kg of coumarone resin, 3-6 kg of polybutadiene, 9-13 kg of Sasol synthetic wax, 0.5-1.8 kg of BHT, surface modification The final magnetic nickel zinc ferrite nanopowder is 8-20 kg; the softening point of the Sasol synthetic wax is between 110°C and 120°C; the plasticizer is low-molecular polybutadiene with a molecular weight of 2300.

Example 16

To make magnetic hot melt adhesive, 27-35 kg of polyvinyl chloride, 26-40 kg of rosin, 3-6 kg of dibutyl phthalate, 9-13 kg of microcrystalline wax, 0.5-1.8 kg of RC, surface modification The final magnetic manganese zinc ferrite nano powder is 8-20 kg; the softening point of the microcrystalline wax is between 60°C-90°C.

Example 17

To make magnetic hot melt adhesive, 27-35 kg of EEA, 26-40 kg of coumarone resin, 3-6 kg of dioctyl phthalate, 9-13 kg of microcrystalline wax, 0.5-1.8 kg of RC, surface modification 8-20 kg of magnetic manganese-zinc-ferrite nano-powder after curing; the softening point of the microcrystalline wax is between 60°C and 90°C.

Example 18

To make magnetic hot melt adhesive, 27-35 kg of EAA, 26-40 kg of coumarone resin, 3-6 kg of dioctyl phthalate, 9-13 kg of Sasol synthetic wax, 0.5-1.8 kg of RC, surface The modified magnetic manganese zinc ferrite nano powder weighs 10-20 kg; the softening point of the Sasol synthetic wax is between 110 DEG C and 120 DEG C.

Example 19

To make magnetic hot melt adhesive, DAP 27-35 kg, rosin 26-40 kg, dibutyl phthalate 3-6 kg, Sasol synthetic wax 9-13 kg, RC 0.5-1.8 kg, after surface modification The magnetic manganese zinc ferrite nano powder is 10-20 kg; the softening point of the Sasol synthetic wax is between 110°C and 120°C.

Claims (9)

1. A magnetic hot-melt adhesive, characterized in that, according to the number of parts by weight: thermoplastic polymer is 10-60 parts, tackifier is 25-55 parts, plasticizer is 2-20 parts, viscosity regulator is 3-15 parts, 0.1-4.5 parts of antioxidant, 5-30 parts of nano-magnetic ferrite after surface modification; The nano-magnetic ferrite is nickel-zinc, manganese-zinc or cobalt-zinc ferrite magnetic nanoparticles prepared by polyol method; the magnetic content of the ferrite is 30-70wt%, and the average particle diameter of the ferrite is 6nm-80nm. 2. A kind of magnetothermal melt adhesive according to claim 1, is characterized in that, described thermoplastic polymer is ethylene-vinyl acetate copolymer, polyamide resin, polyester resin, polyurethane resin, polypropylene resin, polypropylene resin Vinyl acetate resin, styrene-diene-styrene ternary block copolymer, polyvinyl alcohol, polyethylene, polyvinyl chloride, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, polyphthalic acid One or more mixtures of diallyl esters. 3. a kind of magnetothermal melt adhesive according to claim 1, is characterized in that, described tackifier is rosin and derivative thereof, terpene resin, petroleum resin, phenolic resin, coumarone resin species or a mixture of several species. 4. A kind of magnetic hot melt adhesive according to claim 1, is characterized in that, described plasticizer is dioctyl phthalate, dibutyl phthalate, tricresyl phosphate, naphthenic oil , Polybutadiene or a mixture of several. 5. A kind of magnetothermal melt adhesive according to claim 1, is characterized in that, described viscosity modifier is one or in paraffin wax, sasol synthetic wax, microcrystalline wax, ozokerite, low molecular polyethylene wax A mixture of several. 6. A kind of magnetothermal melt adhesive according to claim 1, is characterized in that, described antioxidant is 2,6-tert-butyl p-cresol, antioxidant 1010, 4,4-mercaptobis(6 - tert-butyl xylenol), one or more mixtures of thiodipropionate. 7. the preparation method of a kind of magnetothermal melt adhesive according to claim 1, is characterized in that, comprises the following steps: 1) Put the tackifier, antioxidant, and viscosity regulator into the container, and heat it to above 60°C, stir evenly to melt the mixture; 2) After the mixture prepared in step 1) is completely melted, add thermoplastic polymer and plasticizer respectively, and stir evenly at 150-180°C; 3) After the mixture prepared in step 2) is completely melted and mixed, add the surface-modified magnetic nano-ferrite powder and stir evenly; 4) Stop heating the mixture prepared in step 3), make its temperature drop to ≤130°C, and filter through a 200-300 mesh filter screen; 5) Put the filtered compound in step 4) in an extruder, extrude it at 100-160°C, and then undergo cooling, pelletizing and drying to obtain the magnetic hot-melt adhesive. 8. The using method of a kind of magnetothermal melt adhesive according to claim 1, characterized in that, the following method 1) or 2) can be selected: 1) When the magnetic hot melt adhesive is used for pasting, spread the magnetic hot melt adhesive on the surface to be bonded, add an alternating magnetic field to melt it, stick the two bonding surfaces together, and wait for the magnetic hot melt to melt. After the gel is solidified; 2) When the solidified magnetothermal melt adhesive layer is separated, an alternating magnetic field is applied on the bonding surface to remelt the magnetothermal melt adhesive to achieve re-separation. 9. The using method of a kind of magnetothermal melt adhesive according to claim 8, characterized in that, the alternating magnetic field strength is 5-15kA/m, the alternating heating current is 10-100A, and the magnetic field frequency is 100- 180kHz.