Acrylic resin polyol composition, moisture-curing hot melt adhesive and preparation method

Abstract

The invention relates to an acrylic resin polyol composition, a moisture-curing hot melt adhesive and a preparation method. The acrylic resin polyol composition comprises the following raw materials: 1-40 parts of first acrylic resin; 2 to 50 parts of second acrylic resin; 50 to 100 parts of polyol; the first acrylic resin and the second acrylic resin are prepared by continuously performing free radical polymerization in polyhydric alcohol in a segmented manner; the raw materials of the first acrylic resin comprise methyl methacrylate and first alkyl (meth) acrylate; the raw materials of the second acrylic resin comprise second alkyl (meth) acrylate and silicon-containing (meth) acrylate; the glass transition temperature of the first acrylic resin is 60-90 DEG C, and the glass transition temperature of the second acrylic resin is 20-45 DEG C. The acrylic resin polyol composition is suitable for a moisture-curing hot melt adhesive, can realize dynamic balance of relatively good initial adhesion strength and relatively long opening time, and has good low temperature resistance.

Description

Technical Field

[0001] The present invention relates to the field of adhesives, and in particular to an acrylic resin polyol composition, a moisture-curing hot melt adhesive and a preparation method thereof. Background Art

[0002] Moisture-curing hot melt adhesive is an adhesive with a urethane prepolymer containing an isocyanate group at the end as the main component. It is widely used in various fields such as textile materials, woodworking materials, construction materials and electronic materials. Moisture-curing hot melt adhesive is solid or semi-solid at room temperature. It melts when heated to a certain temperature and becomes fluid and is coated on a substrate. It is then attached to another adherend and cooled and solidified for initial bonding. It then absorbs moisture from the atmosphere to cross-link the isocyanate groups for moisture-curing, thereby increasing the molecular weight of the urethane prepolymer, thereby improving the cohesive strength, heat resistance and final bonding strength of the hot melt adhesive. An ideal moisture-curing hot melt adhesive should have high initial bonding strength, high final bonding strength and a long open time. By adding thermoplastic acrylic resin and utilizing the physical cooling effect of the thermoplastic acrylic resin, the initial cohesive strength of the moisture-curing hot melt adhesive can be improved and the initial bonding strength can be increased.

[0003] U.S. Patent No. 5,021,507 discloses improving the initial cohesive strength and thus the initial bonding strength of a moisture-curing hot melt adhesive by adding an acrylic resin. However, the open time of the hot melt adhesive is less than ideal. Chinese Patent No. CN100547009C discloses a moisture-curing hot melt adhesive prepared by adding a mixed acrylic resin powder containing high and low molecular weight, exhibiting good initial bonding strength and a long open time. However, the acrylic resin powder is mainly prepared by emulsion polymerization or suspension polymerization, and inevitably contains emulsifier and dispersant residues that migrate to the product surface, potentially adversely affecting the final product performance. Chinese Patent No. CN111286294A discloses preparing an acrylic resin in a polyether polyol, directly applying it to the synthesis of a urethane prepolymer without separation and purification, to prepare a moisture-curing hot melt adhesive with good initial tack and sustained tack. However, the acrylic resin prepared in this manner has a single glass transition temperature, making it difficult to achieve a dynamic balance between the initial bonding strength and open time of the moisture-curing hot melt adhesive. Furthermore, the acrylic resin lacks good temperature adaptability, making it difficult to meet the bonding requirements under different seasonal temperature conditions. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the first object of the present invention is to provide an acrylic resin polyol composition suitable for moisture-curing hot melt adhesives, which can achieve a dynamic balance between good initial adhesion strength and long open time and has good low-temperature resistance.

[0005] The second object of the present invention is to provide a method for preparing the acrylic resin polyol composition.

[0006] A third object of the present invention is to provide a moisture-curable hot melt adhesive comprising the acrylic resin polyol composition, wherein the moisture-curable hot melt adhesive has good initial tack strength, long open time and good temperature adaptability.

[0007] A fourth object of the present invention is to provide a method for preparing the moisture-curing hot melt adhesive.

[0008] To achieve the first object of the present invention, the present invention provides an acrylic resin polyol composition, comprising the following raw materials, in parts by weight: 1 to 40 parts of a first acrylic resin; 2 to 50 parts of a second acrylic resin; and 50 to 100 parts of a polyol. The first acrylic resin and the second acrylic resin are prepared by continuous and segmented free radical polymerization in the polyol. The first acrylic resin is obtained by polymerizing a first monomer mixture comprising methyl methacrylate and a first alkyl (meth)acrylate in the polyol. The second acrylic resin is obtained by polymerizing a second monomer mixture comprising a second alkyl (meth)acrylate and a silicon-containing (meth)acrylate in a polyol solution comprising the first acrylic resin. The number of carbon atoms of the alkyl group in the first alkyl (meth)acrylate is 2 to 12; the number of carbon atoms of the alkyl group in the second alkyl (meth)acrylate is 1 to 8. The first acrylic resin has a glass transition temperature of 60 to 90° C. and a weight-average molecular weight of 30,000 to 70,000. The second acrylic resin has a glass transition temperature of 20 to 45° C. and a weight-average molecular weight of 20,000 to 60,000.

[0009] In some embodiments of the present invention, in the first monomer mixture, the content of methyl methacrylate is 40-80 wt % and the content of the first alkyl (meth)acrylate is 20-60 wt % relative to the total weight of the first monomer mixture.

[0010] In some embodiments of the present invention, in the second monomer mixture, the content of the second alkyl (meth)acrylate is 70-95 wt %, and the content of the silicon-containing (meth)acrylate is 5-30 wt %, relative to the total weight of the second monomer mixture.

[0011] In some embodiments of the present invention, the first monomer mixture or the second monomer mixture further comprises a functional monomer, wherein the functional monomer is one or both of (meth)acrylic acid and hydroxyalkyl (meth)acrylate, and the content of the functional monomer is 0.5 to 10 wt % relative to the total weight of the first monomer mixture or the second monomer mixture.

[0012] In some embodiments of the present invention, the silicon-containing (meth)acrylate comprises one or more of trimethylsilyl methacrylate, acryloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxydimethylmethoxysilane, and acryloxytriisopropylsilane.

[0013] In some embodiments of the present invention, the polyol comprises one or more of polyether polyol, polycarbonate polyol, polycaprolactone polyol and polyetherester polyol; the polyether polyol comprises polyethylene glycol, polypropylene glycol, polytetramethylene glycol or random or block copolymers of these polyethers or mixtures thereof; and the number average molecular weight of the polyol is 400 to 4000.

[0014] In some embodiments of the present invention, the polymeric raw material of the first acrylic resin and the polymeric raw material of the second acrylic resin both contain a chain transfer agent and an initiator.

[0015] In some embodiments of the present invention, the chain transfer agent comprises one or more of n-octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan, terpinolene, isooctyl thioglycolate, isooctyl mercaptopropionate, and α-methylstyrene dimer.

[0016] In some embodiments of the present invention, the initiator comprises one or more of lauroyl peroxide, 1,1'-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-amyl peroxy-2-ethylhexanoate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, and 1,1'-bis(tert-butylperoxy)cyclohexane.

[0017] In some embodiments of the present invention, relative to 100 parts by weight of the total weight of the first monomer mixture or the second monomer mixture, the amount of the chain transfer agent used is 0.1 to 3 parts by weight; the amount of the initiator used is 0.5 to 5 parts by weight.

[0018] To achieve the second object of the present invention, the present invention provides a method for preparing the acrylic resin polyol composition described in any of the above schemes, comprising the following steps:

[0019] Step 1: Weigh the first part of the first monomer mixture, the first part of the chain transfer agent, the first part of the initiator and the first part of the polyol, mix them evenly as the first dropwise addition part;

[0020] Step 2: Weigh the second portion of the first monomer mixture, the second portion of the chain transfer agent, and the second portion of the polyol, mix them evenly, add them to the reactor, and heat to 84-88° C. under a nitrogen atmosphere;

[0021] Step 3: Add the first portion obtained in step 1 dropwise to the reactor in step 2, and add the mixture dropwise for 3 to 4 hours at a constant temperature of 84 to 88° C. under a nitrogen atmosphere;

[0022] Step 4: Weigh the second monomer mixture, the third part of the chain transfer agent, the second part of the initiator and the third part of the polyol, mix them evenly and prepare the second dropwise addition part;

[0023] Step 5: After the addition in step 3 is completed, the reaction is maintained at a constant temperature of 84-88°C for 1-2 hours, then the temperature is raised to 112-116°C, and the second portion obtained in step 4 is continued to be added dropwise, and the temperature is maintained at 112-116°C for 2-3 hours;

[0024] Step 6: After the step 5 is completed, add the third part of the initiator to the reactor every 0.5 to 2 hours, and add 1 to 3 times in total. Then, react at a constant temperature of 122 to 126° C. for 1 to 3 hours, and discharge the material while hot to obtain an acrylic resin polyol composition.

[0025] In some embodiments of the present invention, the weight ratio of the first part of the first monomer mixture to the second part of the first monomer mixture is 8:(1-3).

[0026] In some embodiments of the present invention, the weight ratio of the first portion of chain transfer agent, the second portion of chain transfer agent, and the third portion of chain transfer agent is 12:(2-3):(3-10).

[0027] In some embodiments of the present invention, the weight ratio of the first part of the initiator, the second part of the initiator and the third part of the initiator is 9:(5-18):(0.1-4).

[0028] In some embodiments of the present invention, the weight ratio of the first part of polyol, the second part of polyol and the third part of polyol is (2-3):(7-10):(3-5).

[0029] To achieve the third object of the present invention, the present invention also provides a moisture-curing hot melt adhesive comprising an acrylic resin polyol composition and a polyester polyol as described in any of the above schemes, wherein the weight ratio of the acrylic resin polyol composition to the polyester polyol is (0.6-5):1.

[0030] In some embodiments of the present invention, the polyester polyol comprises one or more of an amorphous polyester polyol, a crystalline polyester polyol, and a liquid polyester polyol.

[0031] In some embodiments of the present invention, the number average molecular weight of the polyester polyol is 1000-8000.

[0032] In some embodiments of the present invention, the moisture-curing hot melt adhesive further comprises polyisocyanate.

[0033] In some embodiments of the present invention, the polyisocyanate comprises one or more of isophthalic acid diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, and 1,4-cyclohexane diisocyanate.

[0034] In some embodiments of the present invention, the R value of the polyisocyanate and the polyol is 1.6 to 2.4.

[0035] To achieve the fourth object of the present invention, the present invention further provides a method for preparing the moisture-curing hot melt adhesive, comprising the following steps:

[0036] Step 1: Mix the acrylic resin polyol composition and the polyester polyol and stir them evenly, and dehydrate them under vacuum at 110° C. to 130° C. for 2 to 3 hours, maintaining the vacuum degree below -0.095 MPa;

[0037] Step 2: Cool to 90-100°C, break the vacuum with nitrogen, add the measured polyisocyanate, and react at 100-110°C for 2-3 hours. Keep the vacuum degree below -0.095MPa during the reaction process. After the reaction is completed, discharge the material while hot under nitrogen atmosphere to obtain moisture-curing hot melt adhesive.

[0038] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0039] The present invention designs two acrylic resins with different glass transition temperatures, and prepares an acrylic resin polyol composition by continuously performing free radical polymerization in a polyol medium in sections. It does not require separation and purification and can be directly used in the synthesis of urethane prepolymers. The moisture-curing hot melt adhesive prepared by this technical solution can achieve a dynamic balance between good initial adhesion strength and long open time by adjusting the ratio of the two acrylic resins, and by introducing silicon-containing (meth)acrylate monomers into the acrylic resin, the acrylic resin is given excellent low-temperature resistance. The moisture-curing hot melt adhesive prepared by this solution can maintain good bonding strength even in a -10°C environment, and also has good bonding performance at 30°C. It can meet the bonding requirements at temperatures in different seasons and can be widely used in industries such as woodworking, textiles, construction, and electronics. DETAILED DESCRIPTION

[0040] An embodiment of the present invention provides an acrylic resin composition, which can be used to prepare a urethane prepolymer and is suitable for use as a moisture-curing hot melt adhesive.

[0041] Specifically, the acrylic resin composition comprises, by weight, 1 to 40 parts of a first acrylic resin (A), 2 to 50 parts of a second acrylic resin (B), and 50 to 100 parts of a polyol.

[0042] The polyol is not only a raw material for preparing the urethane prepolymer, but also a medium for polymerization and dispersion of the first acrylic resin (A) and the second acrylic resin (B).

[0043] The first acrylic resin (A) and the second acrylic resin (B) are prepared by continuous free radical polymerization in a polyol medium, that is, the first acrylic resin (A) and the second acrylic resin (B) are prepared successively by free radical polymerization in a polyol medium. The obtained acrylic resin polyol composition does not require separation and purification and can be directly used in the synthesis of urethane prepolymers.

[0044] The first acrylic resin (A) is obtained by polymerizing a first monomer mixture (a) comprising methyl methacrylate and a first alkyl (meth)acrylate (ma) in a polyol medium. The alkyl group in the first alkyl (meth)acrylate (ma) has 2 to 12 carbon atoms. Methyl methacrylate imparts a high glass transition temperature to the first acrylic resin (A). The first acrylic resin (A) has a glass transition temperature of 60 to 90°C and a weight-average molecular weight of 30,000 to 70,000.

[0045] The second acrylic resin (B) is obtained by polymerizing a monomer mixture (b) comprising a second alkyl (meth)acrylate (mb) and a silicon-containing (meth)acrylate in the presence of a polyol solution containing the first acrylic resin (A). The alkyl group in the second alkyl (meth)acrylate (mb) has 1 to 8 carbon atoms, and the silicon-containing (meth)acrylate imparts excellent low-temperature resistance to the second acrylic resin (B). The second acrylic resin (B) has a glass transition temperature of 20 to 45°C and a weight-average molecular weight of 20,000 to 60,000.

[0046] This embodiment uses two acrylic resins with different glass transition temperatures. By adjusting the ratio of the two acrylic resins, the moisture-curing hot melt adhesive can have a dynamic balance between good initial adhesion strength and a long open time. It also has good low-temperature resistance. Even in an environment of -10°C, it can still maintain good bonding strength and has good bonding performance at 30°C. It can meet the bonding requirements under different seasonal temperatures and can be widely used in industries such as woodworking, textiles, construction, and electronics.

[0047] In some examples, the acrylic resin composition is mainly composed of a first acrylic resin (A), a second acrylic resin (B) and a polyol. Other additives or other raw materials may also be added to the acrylic resin composition.

[0048] In some examples, the acrylic resin composition is composed of a first acrylic resin (A), a second acrylic resin (B) and a polyol. The acrylic resin composition does not contain other additives or other raw materials except for necessary impurities and a small amount of residual raw materials such as monomers.

[0049] In some examples, the weight ratio of the first acrylic resin (A), the second acrylic resin (B) and the polyol in the acrylic resin composition is (19-46): (19-46): 100. When each component is within the above range, the acrylic resin composition can better improve the initial adhesion strength and open time of the moisture-curing hot melt adhesive. For example, in parts by weight, based on 100 parts by weight of the polyol, the amount of the first acrylic resin (A) or the second acrylic resin (B) can be 19 parts, 19.5 parts, 20 parts, 20.5 parts, 21 parts, 21.5 parts, 22 parts, 22.5 parts, 23 parts, 23.5 parts, 24 parts, 24.5 parts, 25 parts, 25.5 parts, 26 parts, 26.5 parts, 27 parts, 27.5 parts, 28 parts, 28.5 parts, 29 parts, 29.5 parts, 30 parts, 30.5 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 ​​parts, 49 parts, 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts, 61 parts, 62 parts, 63 parts, 64 parts, 65 parts, 66 parts, 67 parts, 68 parts, 69 parts, 70 parts, 71 parts, 72 parts, 73 parts, 74 parts, 75 parts, 76 parts, 77 parts, 78 parts, 1 part, 31.5 parts, 32 parts, 32.5 parts, 32.6 parts, 33 parts, 33.5 parts, 34 parts, 34.5 parts, 35 parts, 35.5 parts, 36 parts, 36.5 parts, 37 parts, 37.5 parts, 38 parts, 38.5 parts, 39 parts, 39.1 parts, 39.5 parts, 40 parts, 40.5 parts, 41 parts, 41.5 parts, 42 parts, 42.5 parts, 43 parts, 43.5 parts, 44 parts, 44.5 parts, 45 parts, 45.5 parts, 45.6 parts, 46 parts, etc.

[0050] In some examples, the weight ratio of the first acrylic resin (A), the second acrylic resin (B), and the polyol in the acrylic resin composition is (19-40):(25-46):100. When the weights of the components are within the above ranges, the acrylic resin polyol composition can further improve the initial tack strength and open time of the moisture-curing hot melt adhesive.

[0051] In some examples, the first monomer mixture (a) comprises 40-80% by weight of methyl methacrylate and 20-60% by weight of the first alkyl (meth)acrylate (MA) relative to the total weight of the first monomer mixture (a). When the amounts of methyl methacrylate and the first alkyl (meth)acrylate (MA) are within these ranges, the resulting moisture-curable hot melt adhesive can maintain good adhesion over a wide temperature range.

[0052] In some examples, the first monomer mixture (a) comprises 52 to 75% by mass of methyl methacrylate, for example, 52.5 to 75% by mass, and the first alkyl (meth)acrylate (MA) comprises 22 to 45% by mass, for example, 22.5 to 45% by mass, relative to the total weight of the first monomer mixture (a). When the amounts of methyl methacrylate and the first alkyl (meth)acrylate (MA) are within these ranges, the resulting moisture-curable hot melt adhesive can improve high-temperature adhesion.

[0053] In some examples, the second monomer mixture (b) comprises 70-95% by weight of the second alkyl (meth)acrylate (mb), and 5-30% by weight of the silicon-containing (meth)acrylate, relative to the total weight of the second monomer mixture (b). When the amounts of the second alkyl (meth)acrylate (mb) and the silicon-containing (meth)acrylate are within these ranges, the resulting moisture-curable hot melt adhesive can maintain good adhesion over a wide temperature range.

[0054] In some examples, the second monomer mixture (b) includes the second alkyl (meth)acrylate (mb) in an amount of 85-95% by weight, for example, 85-88.5% by weight, and the silicon-containing (meth)acrylate in an amount of 5-15% by weight, for example, 10-15% by weight, relative to the total weight of the second monomer mixture (b). When the amounts of the second alkyl (meth)acrylate (mb) and the silicon-containing (meth)acrylate are within these ranges, the resulting moisture-curable hot melt adhesive can improve low-temperature adhesion.

[0055] In some examples, the first alkyl (meth)acrylate (ma) is one or more of ethyl methacrylate, n-butyl methacrylate, ethyl acrylate, and lauryl acrylate.

[0056] In some examples, the second alkyl (meth)acrylate (mb) is one or more of methyl methacrylate, n-butyl methacrylate, ethyl acrylate, and lauryl acrylate.

[0057] In some examples, the silicon-containing (meth)acrylate includes one or more of trimethylsilyl methacrylate, acryloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxydimethylmethoxysilane, and acryloxytriisopropylsilane.

[0058] In some examples, the first monomer mixture (a) or the second monomer mixture (b) further includes a functional monomer, wherein the functional monomer is one or both of (meth)acrylic acid and hydroxyalkyl (meth)acrylate, and the functional monomer is present in an amount of 0.5 to 10 wt % relative to the total weight of the first monomer mixture or the second monomer mixture. The functional monomer can improve the adhesion of the adhesive. The functional monomer may be present in an amount of 0.7 to 5 wt %, for example, 2.5 to 5 wt %, relative to the total weight of the first monomer mixture or the second monomer mixture.

[0059] In some examples, the polymerization raw material composition of the first acrylic resin (A) and the second acrylic resin (B) further includes a chain transfer agent and an initiator. The chain transfer agent includes one or more of n-octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan, terpinolene, isooctyl thioglycolate, isooctyl thiopropionate, and α-methylstyrene dimer. The initiator includes one or more of lauroyl peroxide, 1,1'-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-amyl peroxy-2-ethylhexanoate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, and 1,1'-bis(tert-butylperoxy)cyclohexane. The chain transfer agent and initiator promote free radical polymerization and chain transfer between the first acrylic resin (A) and the second acrylic resin (B).

[0060] In some examples, based on 100 parts by mass of the monomer mixture (a) or (b), the amount of the chain transfer agent used is 0.1 to 3 parts by mass; and the amount of the initiator used is 0.5 to 5 parts by mass.

[0061] In some examples, the polyol is a polyol, including one or more of polyether polyols, polycarbonate polyols, polycaprolactone polyols, and polyetherester polyols. Suitable polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or random or block copolymers of these polyethers, and mixtures thereof. The polyol has a number average molecular weight of 400 to 4000.

[0062] In some examples, the moisture-curable hot melt adhesive comprises a mixture obtained by uniformly mixing the acrylic resin polyol composition and a polyester polyol, and the resulting polyol-containing mixture is used to prepare a urethane prepolymer, wherein the weight ratio of the acrylic resin polyol composition to the polyester polyol is 0.6:1 to 5:1.

[0063] In some examples, the weight ratio of the acrylic resin polyol composition to the polyester polyol is (3.3-3.7):1, for example, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, etc. When the weight ratio of the acrylic resin polyol composition to the polyester polyol is within the above range, the adhesive strength and temperature resistance of the adhesive can be improved.

[0064] In some examples, the polyester polyol comprises one or more of an amorphous polyester polyol, a crystalline polyester polyol, and a liquid polyester polyol, and the polyester polyol has a number average molecular weight of 1,000 to 8,000.

[0065] In some examples, the moisture-curing hot melt adhesive further comprises a polyisocyanate. The polyisocyanate comprises one or more of isophthalic acid diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, and 1,4-cyclohexane diisocyanate. The R value of the polyisocyanate and the polyol is 1.6 to 2.4, where the R value is the ratio of the isocyanate group to the hydroxyl group. The polyisocyanate can react with an acrylic resin polyol composition or a polyester polyol to obtain a urethane prepolymer. The isocyanate groups in the urethane prepolymer can further cure and bond in moisture, such as air with a certain humidity, thereby achieving a bonding effect.

[0066] In some examples, the method for preparing the acrylic resin polyol composition comprises the following steps:

[0067] (1) Weighing the first portion of the first monomer mixture (a), the first portion of the chain transfer agent, the first portion of the initiator, and the first portion of the polyol, and mixing them uniformly as the first dropwise addition portion;

[0068] (2) Weighing the second portion of the first monomer mixture (a), the second portion of the chain transfer agent, and the second portion of the polyol, mixing them evenly, adding them to the reaction kettle, and heating them to 84-88° C. under a nitrogen atmosphere;

[0069] (3) adding the first portion of step (1) dropwise to the reaction vessel of step (2) and adding the solution dropwise for 3 to 4 hours at a constant temperature of 84 to 88° C. under a nitrogen atmosphere;

[0070] (4) Weighing the second monomer mixture (b), the third part of the chain transfer agent, the second part of the initiator, and the third part of the polyol, and mixing them evenly as the second dropwise addition part;

[0071] (5) After the addition of step (3) is completed, the reaction is maintained at a constant temperature of 84-88°C for 1-2 hours, and then the temperature is raised to 112-116°C, and the second portion of step (4) is continued to be added dropwise, and the constant temperature of 112-116°C is maintained for 2-3 hours;

[0072] (6) After the dropwise addition in step (5) is completed, the third portion of initiator is added to the reactor every 0.5 to 2 hours, for example, 1 hour, for a total of 1 to 3 times, for example, 2 times. The mixture is then kept at a constant temperature of 122 to 126° C. for 1 to 3 hours, for example, 2 hours. The mixture is then discharged while hot to obtain an acrylic resin polyol composition.

[0073] In some examples, the weight ratio of the first part of the first monomer mixture (a) to the second part of the first monomer mixture (a) is 8:(1-3), which is beneficial for reaction control.

[0074] In some examples, the weight ratio of the first portion of chain transfer agent, the second portion of chain transfer agent, and the third portion of chain transfer agent is 12:(2-3):(3-10).

[0075] In some examples, the weight ratio of the first part of the initiator, the second part of the initiator and the third part of the initiator is 9:(5-18):(0.1-4), which is conducive to initiating the polymerization reaction at different stages.

[0076] In some examples, the weight ratio of the first part of polyol, the second part of polyol and the third part of polyol is (2-3):(7-10):(3-5), which is beneficial for uniform dispersion of raw materials and control of reaction rate.

[0077] In some examples, a method for manufacturing a moisture-curing hot melt adhesive includes the following steps:

[0078] Step I: The acrylic resin polyol composition and the polyester polyol are mixed and stirred uniformly, and vacuum dehydrated at 110° C. to 130° C. for 2 to 3 hours, maintaining the vacuum degree below -0.095 MPa.

[0079] Step II: Cool to 90-100°C, break the vacuum with nitrogen, add the measured polyisocyanate, and react at 100-110°C for 2-3 hours. Keep the vacuum degree below -0.095 MPa during the reaction. After the reaction is completed, discharge the material while hot under a nitrogen atmosphere to obtain a urethane prepolymer, which is a moisture-curing hot melt adhesive.

[0080] The present invention will be described below by way of Examples and Comparative Examples. However, the present invention is not limited to these Examples as long as the present invention does not depart from the scope of the present invention.

[0081] Here, the glass transition temperature (hereinafter also referred to as "Tg") is a value calculated based on the following FOX equation. In this specification, the unit of Tg is (°C). Specifically, the Tg of an acrylic resin obtained by copolymerizing n monomers can be regarded as a value calculated based on the Tg of the homopolymer of each monomer.

[0082] 1 / (273+Tg)=∑(Wn / (273+Tgn))

[0083] In the formula, Wn represents the mass fraction of monomer n, and Tgn represents the glass transition temperature (° C.) of the homopolymer of monomer n. Here, the mass fraction is the ratio of the charge amount of monomer n to the total charge amount of all monomers.

[0084] The following raw material numbers are used to illustrate the examples:

[0085] (m-1) methyl methacrylate, Tg = 105 ° C;

[0086] (m-2) ethyl methacrylate, Tg = 66°C;

[0087] (m-3) n-butyl methacrylate, Tg = 20°C;

[0088] (m-4) hydroxyethyl methacrylate, Tg = 55°C;

[0089] (m-5) methacrylic acid, Tg = 130°C;

[0090] (m-6) ethyl acrylate, Tg = -22°C;

[0091] (m-7) lauryl acrylate, Tg = -60°C;

[0092] (m-8) acryloyloxytriisopropylsilane, Tg = -15°C;

[0093] (m-9) acryloyloxypropyltrimethoxysilane, Tg = -25 ° C;

[0094] PPG-1000: polypropylene glycol (number average molecular weight 1000);

[0095] PCD-2000; polycarbonate diol (number average molecular weight 2000);

[0096] PCL-3000: polycaprolactone diol (number average molecular weight 3000);

[0097] PH-3500: poly(1,6-hexanediol adipate) (number average molecular weight 3500);

[0098] MDI-100: 4,4-diphenylmethane diisocyanate.

[0099] The preparation of the acrylic resin polyol composition (P-1) will be described in detail below.

[0100] Preparation of (P-1)

[0101] The first monomer mixture (a-1) of the first acrylic resin (A-1) is composed of:

[0102] (m-1) methyl methacrylate 63 g;

[0103] (m-3) n-butyl methacrylate 54 g;

[0104] (m-4) hydroxyethyl methacrylate 3g;

[0105] The second monomer mixture (b-1) of the second acrylic resin (B-1) is composed of:

[0106] (m-2) ethyl methacrylate 56 g;

[0107] (m-5) methacrylic acid 0.8 g;

[0108] (m-6) ethyl acrylate 12 g;

[0109] (m-9) 8 g of acryloxypropyltrimethoxysilane;

[0110] Weigh 90g of monomer mixture (a-1), 3.0g of n-octyl mercaptan, 0.81g of lauroyl peroxide, and 38.375g of PPG-1000, mix them evenly, and add them to the first dropwise addition portion. Weigh 30g of monomer mixture (a-1), 0.6g of n-octyl mercaptan, and 191.875g of PPG-1000, mix them evenly, and add them to the reactor. Install a stirring paddle, condenser reflux tube, and thermometer on the reactor, introduce nitrogen, and raise the temperature to 86°C. Then, begin the dropwise addition of the first dropwise addition portion. Control the dropwise addition rate and maintain a constant temperature of 86°C under a nitrogen atmosphere for 3.5 hours.

[0111] Weigh 80g of monomer mixture (b-1), 0.8g of n-dodecyl mercaptan, 1.6g of 1,1'-bis(tert-butylperoxy)cyclohexane, and 76.75g of PTMG-2000, mix thoroughly, and prepare the second portion for dropwise addition. After the first portion is added, maintain the reaction at 86°C for 1.5 hours. Then, raise the temperature to 115°C and continue adding the second portion, maintaining the temperature at 115°C for 2.5 hours. After the additions are complete, add 0.15g of tert-butyl peroxybenzoate to the reactor every hour for a total of two additions. Then, raise the temperature to 125°C and continue the reaction at this temperature for 2 hours. Discharge the mixture while hot to obtain acrylic resin polyol composition P-1.

[0112] Preparation of acrylic resin polyol compositions (P-2) to (P-4)

[0113] Acrylic resin polyol compositions (P-2) to (P-4) were prepared in the same manner as for (P-1) using the first monomer mixture (a), the second monomer mixture (b), and the polyol according to the compositions shown in Table 1. The glass transition temperatures (Tg) of the acrylic resins (A-1) to (A-4) and (B-1) to (B-4) are values ​​calculated from the compositions of the raw material monomers.

[0114] Table 1

[0115]

[0116]

[0117] Preparation of moisture-curing hot melt adhesives

[0118] Examples 1 to 4 and Comparative Examples 1 to 3

[0119] Moisture-curing hot melt adhesives were prepared by mixing polyol, polyisocyanate, and acrylic resin polyol composition (P) or powdered acrylic resin according to the composition shown in Table 2. Powdered acrylic resins BR106 (Tg=58°C) and BR113 (Tg=75°C) used in the comparative examples were commercially available products.

[0120] Specifically, the acrylic resin polyol composition (P) and the polyester polyol were mixed and stirred uniformly, then vacuum-dehydrated at 120°C for 2 hours, maintaining a vacuum degree below -0.095 MPa. The temperature was then lowered to 95°C, the vacuum was broken with nitrogen, and the measured polyisocyanate was added. The mixture was reacted at 100°C for 3 hours, maintaining a vacuum degree below -0.095 MPa during the reaction. After the reaction was completed, the mixture was discharged while hot under a nitrogen atmosphere to obtain a moisture-curing hot melt adhesive.

[0121] Table 2

[0122]

[0123]

[0124] In order to evaluate the adhesive properties of the moisture-curing hot melt adhesives in the examples and comparative examples, the initial tack strength and the final tack strength at different temperatures were tested; in order to evaluate the coating performance, the viscosity and open time were measured.

[0125] The test procedures and evaluation criteria are shown below.

[0126] (Initial adhesion strength and final adhesion strength)

[0127] Base material: co-extruded board; membrane material: PVC film, thickness 320μm, dyne value 32~34;

[0128] Test conditions: The initial adhesive strength of the comparative example of the embodiment of the present invention was tested for 10 minutes at a temperature of 20°C and a humidity of 45%. The prepared samples were placed in an environment of 5°C and 30°C and a humidity of 45% for 24 hours, respectively, for final adhesive strength testing.

[0129] Test method:

[0130] Heat the moisture-curing hot melt adhesive to 120-130°C and melt it into a fluid state. Roller-coat it on the substrate at a rate of 30g / m2, adhere to the prepared film material, and press the veneer with the same pressure. Cut a 25mm wide PVC film on the veneer and use a handheld tensile gauge to measure the initial adhesion strength at 180° for 10 minutes. Place the prepared samples in an environment of 5°C and 30°C and 45% humidity for 24 hours, cut a 25mm wide PVC film, and use a handheld tensile gauge to measure the final adhesion strength at 5°C and 30°C at 180°.

[0131] (Opening Hours)

[0132] Heat the moisture-curing hot melt adhesive to 120-130°C to melt it into a fluid state. Apply 30g / m² of adhesive to the substrate with a roller. Then, at an ambient temperature of 20°C, press the PVC film onto the substrate with your fingers and quickly peel it off. The open time is the time from the time the hot melt adhesive is applied to the substrate to the time the PVC film is peeled off without any adhesive residue.

[0133] (Viscosity)

[0134] The viscosity was measured using a viscometer (manufactured by Brookfield Engineering Labs).

[0135] The melted moisture-curable hot melt adhesive (10.5 g) was placed in a viscosity tube, a spindle (No. 27) was inserted into the viscometer, and the viscometer was allowed to stand for 30 minutes at 125°C. After rotating the spindle at 10 rpm for 1 minute, the melt viscosity was measured at 125°C.

[0136] As can be seen from Table 2 above, the moisture-curing hot melt adhesives prepared in Examples 1 to 4 of the present invention have better initial adhesion strength and longer open time than those in Comparative Examples 1 to 3, and exhibit better temperature adaptability, with good adhesion at both -10°C and 30°C, which can meet the bonding requirements under different seasonal temperatures.

[0137] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. An acrylic resin polyol composition, characterized in that By weight, it contains the following raw materials: 1 to 40 parts of a first acrylic resin; 2 to 50 parts of a second acrylic resin; 50-100 parts of polyol; The first acrylic resin and the second acrylic resin are prepared by continuous free radical polymerization in the polyol in stages; the first acrylic resin is obtained by polymerizing a first monomer mixture comprising methyl methacrylate and a first alkyl (meth)acrylate in the polyol; and the second acrylic resin is obtained by polymerizing a second monomer mixture comprising a second alkyl (meth)acrylate and a silicon-containing (meth)acrylate in the polyol solution comprising the first acrylic resin. The number of carbon atoms of the alkyl group in the first alkyl (meth)acrylate is 2 to 12; The number of carbon atoms of the alkyl group in the second alkyl (meth)acrylate is 1 to 8; The first acrylic resin has a glass transition temperature of 60 to 90° C. and a weight average molecular weight of 30,000 to 70,000; The second acrylic resin has a glass transition temperature of 20 to 45° C. and a weight average molecular weight of 20,000 to 60,000.

2. An acrylic resin polyol composition according to claim 1, characterized in that In the first monomer mixture, the content of methyl methacrylate is 40 to 80 wt % and the content of the first alkyl (meth)acrylate is 20 to 60 wt % relative to the total weight of the first monomer mixture; and / or, in the second monomer mixture, the content of the second alkyl (meth)acrylate is 70 to 95 wt % and the content of the silicon-containing (meth)acrylate is 5 to 30 wt % relative to the total weight of the second monomer mixture; And / or, the first monomer mixture or the second monomer mixture further contains a functional monomer, wherein the functional monomer is one or both of (meth)acrylic acid and hydroxyalkyl (meth)acrylate, and the content of the functional monomer is 0.5 to 10 wt % relative to the total weight of the first monomer mixture or the second monomer mixture.

3. An acrylic resin polyol composition according to claim 1 or 2, characterized in that The silicon-containing (meth)acrylate comprises one or more of trimethylsilyl methacrylate, acryloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxydimethylmethoxysilane, and acryloxytriisopropylsilane; And / or, the polyol comprises one or more of polyether polyol, polycarbonate polyol, polycaprolactone polyol and polyether ester polyol; the polyether polyol comprises polyethylene glycol, polypropylene glycol, polytetramethylene glycol or random or block copolymers of these polyethers or mixtures thereof; the number average molecular weight of the polyol is 400 to 4000.

4. An acrylic resin polyol composition according to claim 1 or 2, characterized in that The polymerization raw material of the first acrylic resin and the polymerization raw material of the second acrylic resin both contain a chain transfer agent and an initiator; The chain transfer agent comprises one or more of n-octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan, terpinolene, isooctyl thioglycolate, isooctyl mercaptopropionate, and α-methylstyrene dimer; The initiator comprises one or more of lauroyl peroxide, 1,1'-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-amyl peroxy-2-ethylhexanoate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, and 1,1'-bis(tert-butylperoxy)cyclohexane; With respect to 100 parts by weight of the total weight of the first monomer mixture or the second monomer mixture, the amount of the chain transfer agent used is 0.1 to 3 parts by weight; and the amount of the initiator used is 0.5 to 5 parts by weight.

5. The method for preparing an acrylic resin polyol composition according to any one of claims 1 to 4, characterized in that The following steps are involved: Step 1: Weigh the first part of the first monomer mixture, the first part of the chain transfer agent, the first part of the initiator and the first part of the polyol, mix them evenly as the first dropwise addition part; Step 2: Weigh the second part of the first monomer mixture, the second part of the chain transfer agent, and the second part of the polyol, mix them evenly, add them to the reaction kettle, and heat to 84-88° C. under a nitrogen atmosphere; Step 3: Add the first portion obtained in step 1 dropwise to the reactor in step 2, and add the mixture dropwise for 3 to 4 hours at a constant temperature of 84 to 88° C. under a nitrogen atmosphere; Step 4: Weigh the second monomer mixture, the third part of the chain transfer agent, the second part of the initiator and the third part of the polyol, mix them evenly and prepare the second dropwise addition part; Step 5: After the addition in step 3 is completed, the reaction is maintained at a constant temperature of 84-88°C for 1-2 hours, then the temperature is raised to 112-116°C, and the second portion obtained in step 4 is continued to be added dropwise, and the temperature is maintained at 112-116°C for 2-3 hours; Step 6: After the step 5 is completed, add the third part of the initiator to the reactor every 0.5 to 2 hours, and add 1 to 3 times in total. Then, react at a constant temperature of 122 to 126° C. for 1 to 3 hours, and discharge the material while hot to obtain an acrylic resin polyol composition.

6. The preparation method according to claim 5, characterized in that The weight ratio of the first part of the first monomer mixture to the second part of the first monomer mixture is 8:(1-3); and / or, the weight ratio of the first part of the chain transfer agent, the second part of the chain transfer agent and the third part of the chain transfer agent is 12:(2-3):(3-10); and / or, the weight ratio of the first part of initiator, the second part of initiator and the third part of initiator is 9:(5-18):(0.1-4); And / or, the weight ratio of the first part of polyol, the second part of polyol and the third part of polyol is (2-3):(7-10):(3-5).

7. A moisture curing hot melt adhesive, characterized in that The invention comprises an acrylic resin polyol composition and a polyester polyol, wherein the acrylic resin polyol composition is an acrylic resin polyol composition according to any one of claims 1 to 4 or an acrylic resin polyol composition prepared by the preparation method according to claim 5 or 6, and the weight ratio of the acrylic resin polyol composition to the polyester polyol is (0.6-5):

1.

8. The moisture-curing hot melt adhesive according to claim 7, characterized in that The polyester polyol comprises one or more of amorphous polyester polyol, crystalline polyester polyol and liquid polyester polyol; The number average molecular weight of the polyester polyol is 1000-8000.

9. A moisture curing hot melt adhesive according to claim 7 or 8, characterized in that Also contains polyisocyanates; The polyisocyanate comprises one or more of isophthalic acid diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, and 1,4-cyclohexane diisocyanate; The R value of the polyisocyanate and the polyol is 1.6 to 2.

4.

10. The method for preparing a moisture-curing hot melt adhesive according to claim 9, characterized in that The following steps are involved: Step 1: mixing the acrylic resin polyol composition and the polyester polyol uniformly, and dehydrating under vacuum at 110° C. to 130° C. for 2 to 3 hours, maintaining the vacuum degree below -0.095 MPa; Step 2: Cool to 90-100°C, break the vacuum with nitrogen, add the measured polyisocyanate, and react at 100-110°C for 2-3 hours. Keep the vacuum degree below -0.095 MPa during the reaction. After the reaction is completed, discharge the material while hot under a nitrogen atmosphere to obtain a moisture-curing hot melt adhesive.

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