Reactive polyurethane hot melt adhesive for bonding cover plate of household appliance and preparation method of reactive polyurethane hot melt adhesive

Abstract

The invention discloses a household appliance cover plate bonding reaction type polyurethane hot melt adhesive and a preparation method thereof, and belongs to the field of polyurethane hot melt adhesives, the polyurethane hot melt adhesive is prepared from the following raw materials by weight: 5-25 parts of thermoplastic acrylic resin, 10-60 parts of aliphatic polyester polyol, 8-20 parts of polyether glycol, 10-30 parts of isocyanate, 15-40 parts of a filler, 0.01-0.1 part of a stabilizer and 0.05-0.5 part of a catalyst; the content of NCO in the adhesive reaction type polyurethane hot melt adhesive for the household appliance cover plate is 1.0%-3.5%. The adhesive has the advantages of being short in opening time and high in adhesive strength, the production efficiency is improved, and the use requirement for adhesion of household appliance cover plates can be met.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane hot melt adhesives, and in particular to a reactive polyurethane hot melt adhesive for bonding home appliance cover plates and a preparation method thereof. Background Art

[0002] The base material for bonding home appliance covers is mainly the bonding of glass panels and ABS frames. Traditional pressure-sensitive tapes have unsatisfactory load-bearing capacity and chemical resistance, and require manual transfer, which is inefficient. Using PUR products to bond home appliance covers is not only a replacement for adhesives, but also an advancement in production technology. It satisfies consumers' preference for glass panels while achieving automation and reducing production costs. The current industry pain points of reactive polyurethane hot melt adhesives for bonding washing machine covers are slow surface drying, poor bonding strength, and strong odor. The long open time is not conducive to the continuous production operation of home appliance cover bonding, which will increase production costs.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The purpose of the present invention is to provide a reactive polyurethane hot melt adhesive for bonding household appliance cover plates and a preparation method thereof, which has the characteristics of short open time and strong bonding force, can reduce the production cost of household appliance cover plates, improve production efficiency, meet the use requirements of household appliance cover plates, and thus solve the above-mentioned technical problems existing in the prior art.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] A reactive polyurethane hot melt adhesive for bonding home appliance covers is used for bonding a glass panel of a washing machine to an ABS frame. The polyurethane hot melt adhesive has an NCO% content of 1.0% to 3.5%, and is mainly made of the following raw materials in parts by weight: 5 to 25 parts of thermoplastic acrylic resin, 10 to 60 parts of aliphatic polyester polyol, 8 to 20 parts of polyether diol, 10 to 30 parts of isocyanate, 15 to 40 parts of filler, 0.01 to 0.1 parts of stabilizer and 0.05 to 0.5 parts of catalyst.

[0008] Preferably, in the above hot melt adhesive, the glass transition temperature of the thermoplastic acrylic resin is 30° C. to 80° C., the number average molecular weight is 20,000 to 80,000, and the synthetic monomer of the thermoplastic acrylic resin includes at least one of methyl methacrylate and n-butyl methacrylate.

[0009] Preferably, in the above hot melt adhesive, the aliphatic polyester polyol is synthesized from a hexavalent carbon chain diol and a polyvalent carbon chain dibasic acid.

[0010] Preferably, in the above hot melt adhesive, the hydroxyl value of the aliphatic polyester polyol is 10 to 50 mgKOH / g, and the number average molecular weight is 2000 to 10000.

[0011] Preferably, in the above hot melt adhesive, the aliphatic polyester polyol is at least one of poly(neopentyl adipate diol), poly(1,6-hexanediol adipate diol), poly(1,4-butanediol adipate diol) and poly(1,6-dodecanediol adipate diol).

[0012] Preferably, in the above hot melt adhesive, the polyether diol has a propylene oxide structure as the main chain, a hydroxyl value of 30 to 120 mgKOH / g, and a number average molecular weight of 1000 to 4000.

[0013] Preferably, in the above hot melt adhesive, the isocyanate is at least one of 4,4'-diphenylmethane diisocyanate, diphenylmethane-2,4-diisocyanate, 1,5-naphthalene diisocyanate, p-toluenesulfonyl isocyanate, and 4,4-dicyclohexylmethane diisocyanate.

[0014] Preferably, in the above hot melt adhesive, the filler is at least one of talcum powder and calcium carbonate;

[0015] Preferably, in the above hot melt adhesive, the stabilizer is a compound formed by mixing phosphoric acid and polyphosphoric acid in a mass ratio of 1 to 10:1;

[0016] The catalyst is at least one of dibutyltin dilaurate, stannous octoate, triethylenediamine and dimorpholine diethyl ether.

[0017] A method for preparing a reactive polyurethane hot melt adhesive for bonding household appliance covers according to the present invention comprises the following steps:

[0018] Step 1, according to the above-mentioned formula of reactive polyurethane hot melt adhesive for bonding home appliance cover plates, weigh thermoplastic acrylic resin, aliphatic polyester polyol, polyether diol, isocyanate, filler, stabilizer and catalyst;

[0019] Step 2, adding the thermoplastic acrylic resin and polyether diol into a reaction kettle, controlling the temperature to 100-140° C., maintaining the pressure to -0.06-0.095 MPa, stirring to melt and dehydrating for 1-2 hours;

[0020] Step 3, adding the aliphatic polyester polyol into the reactor, controlling the temperature to 100-120° C., maintaining the pressure to -0.06-0.095 MPa, stirring to melt and dehydrating for 1-2 hours;

[0021] Step 4, placing the filler in a vacuum oven at 100-120° C., vacuuming and dehydrating for 1-3 hours, adding it to the reactor, controlling the temperature to 100-120° C., maintaining the pressure at -0.06-0.095 MPa, stirring to melt and dehydrating for 1-2 hours, then cooling to 60-85° C., adding isocyanate, stabilizer and catalyst to the reactor, maintaining the temperature at 80-100° C., maintaining the vacuum degree at -0.06-0.095 MPa, and stirring to react for 0.5-1 hour;

[0022] Step 5, stop stirring, degas for 10 to 20 minutes, filter, and discharge the material to obtain the reactive polyurethane hot melt adhesive for bonding home appliance cover plates as described in any one of claims 1 to 9.

[0023] Compared with the prior art, the present invention provides

[0024] The one-component moisture-curing reactive polyurethane hot melt adhesive for bonding home appliance covers is prepared by using a special preparation method with a specific ratio of isocyanate, aliphatic polyester polyol, polyether diol, thermoplastic acrylic resin and filler, in combination with a specific amount of stabilizer and catalyst; the one-component moisture-curing reactive polyurethane hot melt adhesive for bonding home appliance covers not only has excellent initial adhesion and good lasting adhesion, and has extremely low odor, but also can be quickly cured, and its water resistance and chemical resistance meet the requirements of washing machine cover bonding applications.

[0025] Compared with the prior art, the reactive polyurethane hot melt adhesive for bonding home appliance cover plates and the preparation method thereof provided by the present invention have the following beneficial effects:

[0026] Thermoplastic acrylic resin, aliphatic polyester polyol, polyether diol, isocyanate and filler are used in a specific ratio, in combination with a specific amount of stabilizer and catalyst, and in a specific preparation method; this fast-drying and high-initial-tack polyurethane hot melt adhesive can form a rapid bond to the substrate, and can quickly transfer the assembly to the next processing step to improve work efficiency. In addition, the moisture-curing polyurethane hot melt adhesive contains terminal NCO polyurethane prepolymers. Under high temperature conditions, the active functional groups react with moisture or active hydrogen substances in the air or on the adherend to form a partially cross-linked network structure, which further improves the bonding strength, chemical resistance, heat resistance, hydrolysis resistance and other properties. The hot melt adhesive not only has excellent initial adhesion and good holding force, but also has extremely low odor, and can be quickly cured. The water resistance and chemical resistance meet the requirements of washing machine cover bonding applications. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in combination with the specific content of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0028] First, the terms that may be used in this article are explained as follows:

[0029] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0030] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0031] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0032] The term "parts by mass" refers to the mass ratio relationship between multiple components. For example, if it is described that component X is x parts by mass and component Y is y parts by mass, then the mass ratio of component X to component Y is x:y. 1 part by mass can represent any mass, for example, 1 part by mass can be represented as 1 kg or 3.1415926 kg. The sum of the parts by mass of all components is not necessarily 100 parts, but can be greater than 100 parts, less than 100 parts or equal to 100 parts. Unless otherwise specified, the parts, proportions and percentages described herein are all measured by mass.

[0033] When concentration, temperature, pressure, size or other parameters are expressed in the form of a numerical range, the numerical range should be understood to specifically disclose all ranges formed by the pairing of any upper limit, lower limit, and preferred value in the numerical range, regardless of whether the range is explicitly stated; for example, if a numerical range of "2 to 8" is stated, the numerical range should be interpreted as including ranges such as "2 to 7", "2 to 6", "5 to 7", "3 to 4 and 6 to 7", "3 to 5 and 7", "2 and 5 to 7", etc. Unless otherwise specified, the numerical ranges stated herein include both their end values ​​and all integers and fractions within the numerical range.

[0034] The scheme provided by the present invention is described in detail below. The contents not described in detail in the embodiments of the present invention belong to the prior art known to professionals in the field. If the specific conditions are not specified in the embodiments of the present invention, they are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturers are not specified in the reagents or instruments used in the embodiments of the present invention, they are all conventional products that can be purchased commercially.

[0035] The embodiment of the present invention provides a reactive polyurethane hot melt for bonding home appliance cover plates, which is used for bonding washing machine cover plates. The hot melt is mainly made of the following raw materials in parts by weight: 10 to 30 parts of isocyanate, 10 to 60 parts of aliphatic polyester polyol, 8 to 20 parts of polyether diol, 5 to 25 parts of thermoplastic acrylic resin, 15 to 40 parts of filler, 0.01 to 0.1 parts of stabilizer and 0.05 to 0.5 parts of catalyst; wherein the thermoplastic acrylic resin has a Tg point of 30°C to 80°C and a number average molecular weight of 20,000 to 80,000.

[0036] Specifically, the above-mentioned household appliance cover bonding reactive polyurethane hot melt adhesive may include the following embodiments:

[0037] (1) The isocyanate is at least one of 4,4'-diphenylmethane diisocyanate, diphenylmethane-2,4-diisocyanate, 1,5-naphthalene diisocyanate, p-toluenesulfonyl isocyanate, and 4,4-dicyclohexylmethane diisocyanate. The above isocyanates have high reactivity, and the polyurethane material synthesized from alicyclic isocyanates and aromatic isocyanates has higher strength, wear resistance, and heat resistance.

[0038] (2) The hydroxyl value of the aliphatic polyester polyol is 10 to 50 mgKOH / g, and the number average molecular weight is in the range of 2000 to 10000. The polyester polyol synthesized by using hexavalent carbon chain diol and polyvalent carbon chain dibasic acid, such as polyhexanediol-1,6-adipate diol or polydodecanediol-1,6-hexanediol ester diol, are highly crystalline polyester diols, which can effectively shorten the open time while improving the initial adhesion of the polyurethane hot melt adhesive.

[0039] (3) The polyether diol is a polypropylene oxide ether diol with a propylene oxide structure as the main chain, a hydroxyl value of 30 to 120 mgKOH / g, and a number average molecular weight of 1000 to 4000. The polyether diol has good solubility for thermoplastic acrylic resin and can promote better fluidity of the colloid in a molten state.

[0040] (4) The thermoplastic acrylic resin is mainly an acrylic resin copolymerized from methyl methacrylate and n-butyl methacrylate.

[0041] (5) The filler is at least one of talc and calcium carbonate.

[0042] (6) The stabilizer is a compound of phosphoric acid and polyphosphoric acid in a mass ratio of 1 to 10: 1. The phosphoric acid in the stabilizer can effectively inhibit the violent reaction and prevent the occurrence of implosion.

[0043] (7) The catalyst is at least one of dibutyltin dilaurate, stannous octoate, triethylenediamine, and dimorpholine diethyl ether.

[0044] (8) The NCO% content of the reactive polyurethane hot melt adhesive for bonding household appliance covers provided by the present invention is 1.0% to 3.5%. This specific NCO% content can avoid the generation of excessive CO2 during the curing process of the adhesive layer due to excessively high NCO% and the resulting presence of more bubbles in the adhesive layer. The lower limit value of NCO% can ensure that the adhesive layer has sufficient NCO groups to react and cross-link with moisture in the air and hydroxyl groups on the surface of the substrate, thereby achieving a higher final adhesive layer body strength and forming sufficient chemical bonds with the substrate, that is, achieving a higher final bonding strength.

[0045] The embodiment of the present invention also provides a method for preparing a reactive polyurethane hot melt adhesive for bonding household appliance covers, which is used to prepare the reactive polyurethane hot melt adhesive for bonding household appliance covers, and the method may include the following steps:

[0046] Step 1, according to the formula of the above-mentioned reactive polyurethane hot melt adhesive for bonding home appliance cover plates, weigh isocyanate, aliphatic polyester polyol, polyether diol, thermoplastic acrylic resin, filler, stabilizer and catalyst;

[0047] Step 2, adding the polyether diol and thermoplastic acrylic resin into a reaction kettle, controlling the temperature between 100 and 140° C., maintaining the pressure between -0.06 and -0.095 MPa, stirring to melt and dehydrating for 1 to 2 hours;

[0048] Step 3, adding the aliphatic polyester polyol into the reactor, controlling the temperature between 100 and 120° C., maintaining the pressure between -0.06 and -0.095 MPa, stirring to melt and dehydrating for 1 to 2 hours;

[0049] Step 4, placing the filler in a vacuum oven at 100-120° C., vacuuming and dehydrating for 1-3 hours, adding it to the reactor, controlling the temperature between 100-120° C., maintaining the pressure between -0.06 and -0.095 MPa, stirring to melt and dehydrating for 1-2 hours, then cooling to 60-85° C., adding the catalyst, the stabilizer and the isocyanate to the reactor, maintaining the temperature at 80-100° C., maintaining the vacuum degree at -0.06 to -0.095 MPa, and stirring to react for 0.5-1 hour;

[0050] Step 5, stop stirring, degas for 10 to 20 minutes, filter, and discharge the material, thereby obtaining the above-mentioned reactive polyurethane hot melt adhesive for bonding home appliance cover plates.

[0051] Compared with the prior art, the reactive polyurethane hot melt adhesive for bonding home appliance covers and the preparation method thereof provided in the embodiments of the present invention have at least the following advantages:

[0052] (1) The polyurethane hot melt adhesive uses a prepolymer method to adjust the molecular weight distribution of the synthesized polyurethane resin, which can greatly improve the initial viscosity and wettability of the polyurethane hot melt adhesive to the bonding surface.

[0053] (2) The polyurethane hot melt adhesive does not use thickening resin, can meet the initial bonding requirements, reduce the odor of PUR during the high-temperature melting process, and will not release irritating odor during long-term use, thus meeting quality control requirements and reducing harm to the environment and human health.

[0054] (3) The acrylic resin structure used in the polyurethane hot melt adhesive has excellent heat resistance and hydrolysis resistance, which also improves the overall heat resistance and hydrolysis resistance of the polyurethane hot melt adhesive;

[0055] (4) The aliphatic polyester polyol selected in the present invention is synthesized from a hexavalent carbon chain diol and a polyvalent carbon chain dibasic acid, and has a special hydroxyl value and a special number average molecular weight. Due to its regular structure of a carbon chain with more than six members, the prepared polyurethane hot melt adhesive has a fast crystallization speed and good hydrolysis resistance, and can meet the requirement of a short open time for bonding the washing machine cover.

[0056] (5) Compared with the prior art, the reactive polyurethane hot melt adhesive for bonding home appliance cover plates provided by the present invention has the characteristics of short open time, high bonding strength, strong crack resistance and low cost.

[0057] In summary, the reactive polyurethane hot melt adhesive for bonding household appliance covers in the embodiment of the present invention has the characteristics of short open time and strong later bonding force, and has strong resistance to cracking, which can reduce the production cost of household appliance covers and improve production efficiency.

[0058] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the solution provided by the embodiment of the present invention is described in detail with specific embodiments below.

[0059] First, the raw materials used in the following examples and comparative examples are described:

[0060] MDI-100 refers to 4,4'-diphenylmethane diisocyanate.

[0061] PAA-4000 refers to poly(1,6-hexanediol adipate) and has a number average molecular weight of 4,000.

[0062] PE-3500 refers to poly (1,6-hexanediol dodecanoate) with a number average molecular weight of 3500.

[0063] PPG-400 refers to a polyether diol with propylene oxide as the main chain and a number average molecular weight of 400.

[0064] The stabilizer refers to a compound prepared by mixing phosphoric acid and polyphosphoric acid in a mass ratio of 1 to 10:1.

[0065] The catalyst is at least one of dibutyltin dilaurate, stannous octoate, triethylenediamine and dimorpholine diethyl ether.

[0066] Example 1

[0067] This embodiment provides a reactive polyurethane hot melt adhesive for bonding home appliance cover plates, and a preparation method thereof comprises the following steps:

[0068] Step 1A, weighing various raw materials according to the formula of reactive polyurethane hot melt adhesive for bonding home appliance cover plates;

[0069] Step 2A, add 140 kg of PPG-400 and 160 kg of acrylic resin BR113 in the raw materials into the reactor, open the vacuum to -0.06 to -0.095 MPa, control the temperature between 100 and 140° C., stir to melt and dehydrate for 1 to 2 hours;

[0070] Step 3A, adding 100 kg of PAA-4000 and 140 kg of PE-3500 in the raw materials into the reactor, controlling the temperature between 100 and 120° C., maintaining the pressure between -0.06 and -0.095 MPa, stirring to melt and dehydrating for 1 to 2 hours;

[0071] Step 4A, adding 20 kg of nano calcium carbonate filler that has been heated and dehydrated in a vacuum oven at 100 to 120° C. for 1 to 3 hours into the reactor, controlling the temperature between 100 and 120° C., maintaining the pressure between -0.06 and -0.095 MPa, stirring to melt and dehydrate for 1 to 2 hours, then cooling to 60 to 85° C., adding 0.2 kg of catalyst and 2 kg of stabilizer into the reactor and stirring evenly, adding 20 kg of MDI-100 into the reactor, maintaining the temperature at 80 to 100° C., maintaining the vacuum degree at -0.06 to -0.095 MPa, and stirring to react for 0.5 to 1 hour;

[0072] Step 5A, stop stirring, degas for 10 to 20 minutes, filter, and discharge the material to obtain the reactive polyurethane hot melt adhesive for bonding home appliance cover plates.

[0073] Example 2

[0074] This embodiment provides a reactive polyurethane hot melt adhesive for bonding home appliance cover plates, and a preparation method thereof comprises the following steps:

[0075] Step 1B, weigh the raw materials according to the formula of reactive polyurethane hot melt adhesive for bonding home appliance cover plates;

[0076] Step 2B, add 150 kg of PPG-400 and 150 kg of acrylic resin BR113 in the raw materials into the reactor, open the vacuum to -0.06 to -0.095 MPa, control the temperature between 100 and 140° C., stir to melt and dehydrate for 1 to 2 hours;

[0077] Step 3B, adding 100 kg of PAA-4000 and 150 kg of PE-3500 in the raw materials into the reactor, controlling the temperature between 100 and 120° C., maintaining the pressure between -0.06 and -0.095 MPa, stirring to melt and dehydrating for 1 to 2 hours;

[0078] Step 4B, adding 25 kg of nano calcium carbonate filler that has been heated and dehydrated in a vacuum oven at 100 to 120° C. for 1 to 3 hours to the reactor, controlling the temperature between 100 and 120° C., maintaining the pressure between -0.06 and -0.095 MPa, stirring to melt and dehydrate for 1 to 2 hours, and then cooling to 60 to 85° C.; adding 0.2 kg of catalyst and 2 kg of stabilizer to the reactor and stirring evenly, adding 21 kg of MDI-100 to the reactor, maintaining the temperature at 80 to 100° C., maintaining the vacuum degree at -0.06 to -0.095 MPa, and stirring to react for 0.5 to 1 hour;

[0079] Step 5B, stop stirring, degas for 10 to 20 minutes, filter, and discharge the material to obtain the reactive polyurethane hot melt adhesive for bonding home appliance cover plates.

[0080] Example 3

[0081] This embodiment provides a reactive polyurethane hot melt adhesive for bonding home appliance cover plates, and a preparation method thereof comprises the following steps:

[0082] Step 1C, weighing various raw materials according to the formula of reactive polyurethane hot melt adhesive for bonding home appliance cover plates;

[0083] Step 2C, add 150 kg of PPG-400 and 150 kg of acrylic resin BR113 in the raw materials into the reactor, open the vacuum to -0.06 to -0.095 MPa, control the temperature between 100 and 140° C., stir to melt and dehydrate for 1 to 2 hours;

[0084] Step 3C, adding 150 kg of PAA-4000 and 100 kg of PE-3500 in the raw materials into the reactor, controlling the temperature between 100 and 120° C., maintaining the pressure between -0.06 and -0.095 MPa, stirring to melt and dehydrating for 1 to 2 hours;

[0085] Step 4C, adding 25 kg of nano calcium carbonate filler that has been heated and dehydrated in a vacuum oven at 100 to 120° C. for 1 to 3 hours to the reactor, controlling the temperature between 100 and 120° C., maintaining the pressure between -0.06 and -0.095 MPa, stirring to melt and dehydrate for 1 to 2 hours, and then cooling to 60 to 85° C.; adding 0.2 kg of catalyst and 2 kg of stabilizer to the reactor and stirring evenly, adding 21 kg of MDI-100 to the reactor, maintaining the temperature at 80 to 100° C., maintaining the vacuum degree at -0.06 to -0.095 MPa, and stirring to react for 0.5 to 1 hour;

[0086] Step 5C, stop stirring, degas for 10 to 20 minutes, filter, and discharge the material to obtain the reactive polyurethane hot melt adhesive for bonding home appliance cover plates.

[0087] Comparative Example 1

[0088] A commercially available reactive polyurethane hot melt adhesive for bonding home appliance cover plates was selected as a comparative example.

[0089] Performance Testing

[0090] The reactive polyurethane hot melt adhesives for bonding home appliance covers prepared in Examples 1, 2 and 3 of the present invention and the reactive polyurethane hot melt adhesives for bonding home appliance covers available on the market were subjected to the following parallel comparative performance tests under the same conditions:

[0091] (1) Rotational viscosity: The rotational viscosity at 120°C was measured using a CAP2000 cone-plate viscometer to characterize fluidity.

[0092] (2) Open time: Tested by the sticker method, characterized by the time it takes for the kraft paper to not stick.

[0093] (3) Shear force: In an environment of (RT: 23°C, RH: 50%), the prepared hot melt adhesive ABS substrates were bonded to each other. The shear force was tested after 10 min, 30 min, 1 h, 2 h, 5 h and 24 h. Five samples were tested for each condition and the average value was taken after the test.

[0094] Table 1 is a summary of the test results

[0095]

[0096]

[0097] It can be seen from Table 1 above that: compared with the comparative example, the household appliance cover bonding reactive polyurethane hot melt adhesive of each embodiment of the present invention has a short open time, moderate viscosity, good hot melt fluidity, good initial bonding strength and final bonding strength, and can be well used for the bonding and compounding of the washing machine glass panel and the ABS frame, and can meet the use requirements of household appliance cover bonding.

[0098] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A reactive polyurethane hot melt adhesive for bonding home appliance cover plates, used for bonding washing machine glass panels and ABS frames, characterized in that: The polyurethane hot melt adhesive has an NCO% content of 1.0% to 3.5%, and is mainly made of the following raw materials in parts by weight: 5 to 25 parts of thermoplastic acrylic resin, 10 to 60 parts of aliphatic polyester polyol, 8 to 20 parts of polyether diol, 10 to 30 parts of isocyanate, 15 to 40 parts of filler, 0.01 to 0.1 parts of stabilizer and 0.05 to 0.5 parts of catalyst.

2. The reactive polyurethane hot melt adhesive for bonding home appliance cover plates according to claim 1, characterized in that: The glass transition temperature of the thermoplastic acrylic resin is 30° C. to 80° C., and the number average molecular weight is 20,000 to 80,000. The synthetic monomer of the thermoplastic acrylic resin includes at least one of methyl methacrylate and n-butyl methacrylate.

3. The reactive polyurethane hot melt adhesive for bonding household appliance covers according to claim 1 or 2, characterized in that: The aliphatic polyester polyol is synthesized from hexavalent carbon chain diol and polyvalent carbon chain dibasic acid.

4. The reactive polyurethane hot melt adhesive for bonding home appliance cover plates according to claim 3, characterized in that: The aliphatic polyester polyol is at least one of poly(neopentyl adipate diol), poly(1,6-hexanediol adipate diol), poly(1,4-butanediol adipate diol) and poly(1,6-dodecanediol adipate diol).

5. The reactive polyurethane hot melt adhesive for bonding household appliance covers according to claim 1 or 2, characterized in that: The aliphatic polyester polyol has a hydroxyl value of 10 to 50 mgKOH / g and a number average molecular weight of 2,000 to 10,000.

6. The reactive polyurethane hot melt adhesive for bonding household appliance covers according to claim 1 or 2, characterized in that: The polyether diol has a propylene oxide structure as the main chain, a hydroxyl value of 30 to 120 mgKOH / g, and a number average molecular weight of 1000 to 4000.

7. The reactive polyurethane hot melt adhesive for bonding home appliance covers according to claim 1 or 2, characterized in that: The isocyanate is at least one of 4,4'-diphenylmethane diisocyanate, diphenylmethane-2,4-diisocyanate, 1,5-naphthalene diisocyanate, p-toluenesulfonyl isocyanate, and 4,4-dicyclohexylmethane diisocyanate.

8. The reactive polyurethane hot melt adhesive for bonding home appliance cover plates according to claim 1 or 2, characterized in that: The filler is at least one of talc and calcium carbonate.

9. The reactive polyurethane hot melt adhesive for bonding home appliance cover plates according to claim 1 or 2, characterized in that: The stabilizer is a compound formed by mixing phosphoric acid and polyphosphoric acid in a mass ratio of 1 to 10:1; The catalyst is at least one of dibutyltin dilaurate, stannous octoate, triethylenediamine and dimorpholine diethyl ether.

10. A method for preparing a reactive polyurethane hot melt adhesive for bonding home appliance covers according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1, weighing thermoplastic acrylic resin, aliphatic polyester polyol, polyether diol, isocyanate, filler, stabilizer and catalyst according to the formula of reactive polyurethane hot melt adhesive for bonding home appliance cover plates according to any one of claims 1 to 9; Step 2, adding the thermoplastic acrylic resin and polyether diol into a reaction kettle, controlling the temperature to 100-140° C., maintaining the pressure to -0.06-0.095 MPa, stirring to melt and dehydrating for 1-2 hours; Step 3, adding the aliphatic polyester polyol into the reactor, controlling the temperature to 100-120° C., maintaining the pressure to -0.06-0.095 MPa, stirring to melt and dehydrating for 1-2 hours; Step 4, placing the filler in a vacuum oven at 100-120° C., vacuuming and dehydrating for 1-3 hours, adding it to the reactor, controlling the temperature to 100-120° C., maintaining the pressure at -0.06-0.095 MPa, stirring to melt and dehydrating for 1-2 hours, then cooling to 60-85° C., adding isocyanate, stabilizer and catalyst to the reactor, maintaining the temperature at 80-100° C., maintaining the vacuum degree at -0.06-0.095 MPa, and stirring to react for 0.5-1 hour; Step 5, stop stirring, degas for 10 to 20 minutes, filter, and discharge the material to obtain the reactive polyurethane hot melt adhesive for bonding home appliance cover plates as described in any one of claims 1 to 9.

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