Polyurethane adhesive with high weather resistance and yellowing resistance as well as preparation method and application of polyurethane adhesive

Abstract

The invention discloses a polyurethane adhesive with high weather resistance and yellowing resistance as well as a preparation method and application of the polyurethane adhesive. The polyurethane adhesive is prepared from the following components in parts by weight on the basis of 10 parts of isocyanate: 72 to 457 parts of polymer polyol, 36 to 111 parts of isocyanate oligomer, 30 to 385 parts of polyacrylate polyol, 15 to 191 parts of plasticizer and 0.8 to 9.5 parts of catalyst. The isocyanate adopted by the invention is aliphatic and / or alicyclic isocyanate and oligomer thereof, and no anti-yellowing agent or light stabilizer is added, so that the problem of yellowing of polyurethane can be thoroughly solved. The preparation method comprises the following steps: reacting aliphatic / alicyclic isocyanate with excessive polymer polyol under the assistance of a small amount of a catalyst, so that the low-activity aliphatic / alicyclic isocyanate is completely reacted to obtain a hydroxyl-terminated polyurethane prepolymer; then reacting with an isocyanate oligomer to completely react a terminal hydroxyl group to obtain a polyurethane prepolymer; and then carrying out chain extension by using polypropylene ester polyol to obtain the polyurethane adhesive with a certain structure and excellent weather resistance and yellowing resistance, and the polyurethane adhesive is widely applied to outdoor sports field materials.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane adhesives, and in particular to a highly weather-resistant and yellowing-resistant polyurethane adhesive and a preparation method and application thereof. Background Art

[0002] With the development of social economy and the improvement of people's living standards, various sidewalks, road tracks and sports venues are becoming increasingly popular in many outdoor places such as squares, parks, children's playgrounds, communities, schools, etc. The polyurethane adhesive macromolecule contains a highly polar urethane group, which has excellent mechanical properties, low temperature resistance, aging resistance, oil resistance, corrosion resistance, wear resistance and other advantages. It can be mixed with rubber particles, sand and gravel to pave sports venues; through the cross-linking and curing of polyurethane adhesives, various sports venues with different properties can be obtained to meet people's different sports or leisure needs.

[0003] At present, polyurethane adhesives used for sports venues are mainly synthesized from aromatic isocyanates such as toluene diisocyanate (TDI) or diphenylmethane diisocyanate (MDI). However, the isocyanate groups in TDI and MDI are directly connected to the benzene ring, and they change color and turn yellow in a short period of time after natural aging in environments such as light, humidity and heat. Therefore, for some light-colored or colorful (such as white, green, etc.) sports venues, aromatic polyurethane adhesives cannot meet their yellowing resistance requirements.

[0004] There are two main methods to improve the yellowing resistance of polyurethane adhesives. One is to add a large amount of anti-yellowing agents, light stabilizers, brighteners, etc. This method can only temporarily delay the yellowing time and has limited practical effect; moreover, the large amount of anti-yellowing agents and other additives affect the physical and chemical properties of polyurethane adhesives; the other is to use aliphatic or alicyclic isocyanates instead of aromatic isocyanates, such as isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI) or hexamethylene diisocyanate (HDI). Aliphatic or alicyclic isocyanates do not contain aromatic rings in their molecular structures, which fundamentally solves the yellowing problem of polyurethane materials. However, aliphatic or alicyclic isocyanates do not have the conjugation effect of benzene rings, and their reactivity is lower than that of aromatic isocyanates. Moreover, the mechanical properties, wear resistance, and solvent resistance of the prepared polyurethane adhesives are poor, especially their weather resistance is much lower than that of polyurethane adhesives prepared from aromatic isocyanates. Outdoor sports venues paved with polyurethane adhesives based on aliphatic or alicyclic isocyanates are prone to aging and stickiness. Therefore, it is urgent to develop polyurethane adhesives for outdoor sports venues that are both weather-resistant and yellowing-resistant, so as to fundamentally solve the problem of yellowing resistance. Summary of the invention

[0005] The main purpose of the present invention is to provide a highly weather-resistant and yellowing-resistant polyurethane adhesive and a preparation method and application thereof, which overcomes the problem of insufficient weather resistance of polyurethane adhesives prepared using aliphatic and / or alicyclic isocyanates.

[0006] To achieve the above-mentioned object, the present invention provides a highly weather-resistant and yellowing-resistant polyurethane adhesive, comprising the following raw materials in parts by weight: based on 10 parts of isocyanate, 72 to 457 parts of polymer polyol, 36 to 111 parts of isocyanate oligomer, 30 to 385 parts of polyacrylate polyol, 15 to 191 parts of plasticizer and 0.8 to 9.5 parts of catalyst, wherein the isocyanate comprises at least one of aliphatic isocyanate and alicyclic isocyanate; the polymer polyol comprises polycarbonate diol, and the molecular weight of the polycarbonate diol is 1000 to 4000; the isocyanate oligomer comprises an addition product of aliphatic isocyanate and / or alicyclic isocyanate and trimethylolpropane; the molecular weight of the polyacrylate polyol is 4000 to 8000, and the hydroxyl value of the polyacrylate polyol is 28 to 56 mg KOH / g.

[0007] Optionally, the isocyanate includes at least one of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, methylcyclohexyl diisocyanate and cyclohexyl diisocyanate.

[0008] Optionally, the isocyanate oligomer includes at least one of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and an addition product of isophorone diisocyanate and trimethylolpropane.

[0009] Optionally, the plasticizer includes at least one of dibutyl phthalate and dioctyl phthalate; and / or,

[0010] The catalyst comprises an organic metal compound, and the organic metal compound comprises at least one of stannous isooctanoate, stannous octoate, dibutyltin dilaurate and dibutyltin dichloride.

[0011] The present invention also provides a method for preparing the highly weather-resistant and yellowing-resistant polyurethane adhesive as described above, which is used to prepare the highly weather-resistant and yellowing-resistant polyurethane adhesive as described above, comprising the following steps:

[0012] S10, dehydrating 72 to 457 parts of polymer polyol under reduced pressure at 95 to 115° C., mixing with 10 parts of isocyanate and 0.4 to 4.8 parts of catalyst, reacting at 70 to 90° C. for 3 to 6 hours, and cooling to obtain hydroxyl-terminated polyurethane prepolymer A;

[0013] S20, mixing the hydroxyl-terminated polyurethane prepolymer A with 36 to 111 parts of isocyanate oligomer, reacting at 60 to 85° C. for 2 to 5 hours, and cooling to obtain a polyurethane prepolymer B;

[0014] S30, dehydrating 30 to 385 parts of polyacrylate polyol under reduced pressure at 95 to 115° C., reacting with polyurethane prepolymer B at 55 to 80° C. for 2 to 4 hours, and cooling to obtain polyurethane prepolymer C;

[0015] S40, dehydrating 15 to 191 parts of plasticizer under reduced pressure at 95 to 105° C., mixing with the polyurethane prepolymer C at room temperature, and adding the remaining catalyst; stirring and mixing evenly, and degassing to obtain a highly weather-resistant and yellowing-resistant polyurethane adhesive.

[0016] The present invention also proposes a composite material for sports fields, which includes a highly weather-resistant and yellowing-resistant polyurethane adhesive. The highly weather-resistant and yellowing-resistant polyurethane adhesive is such as any one of the highly weather-resistant and yellowing-resistant polyurethane adhesives described above or a highly weather-resistant and yellowing-resistant polyurethane adhesive prepared by the method for preparing the highly weather-resistant and yellowing-resistant polyurethane adhesive described above.

[0017] The technical solution provided by the present invention comprises the following raw materials in parts by mass: based on 10 parts of isocyanate, 72 to 457 parts of polymer polyol, 36 to 111 parts of isocyanate oligomer, 30 to 385 parts of polyacrylate polyol, 15 to 191 parts of plasticizer and 0.8 to 9.5 parts of catalyst. The isocyanate used in the present invention is aliphatic and / or alicyclic isocyanate and its addition product, and no anti-yellowing agent or light stabilizer is added, which can completely solve the problem of yellowing of polyurethane.

[0018] In the embodiment of the present invention, an excess of polycarbonate polyol is used to react with aliphatic / alicyclic isocyanate, assisted by a small amount of catalyst, so that the isocyanate of the low-activity aliphatic / alicyclic isocyanate is completely reacted to obtain a terminal hydroxyl polyurethane prepolymer, which solves the problem of low activity and incomplete reaction of aliphatic and / or alicyclic isocyanate; then an excess of isocyanate oligomer is used to react with the terminal hydroxyl polyurethane prepolymer to obtain a terminal isocyanate polyurethane prepolymer; finally, polyacrylate polyol is used for chain extension to obtain a polyurethane adhesive. The yellowing-resistant polyurethane adhesive prepared by the present invention has excellent weather resistance, which overcomes the problem of insufficient weather resistance of the polyurethane adhesive prepared by using aliphatic and / or alicyclic isocyanate. On the one hand, the polymerization process and raw materials are adjusted to make the aliphatic and / or alicyclic isocyanate react completely, thereby improving the aging performance of the polyurethane. On the other hand, the introduction of polyacrylate chain segments through the chain extension reaction of polyacrylate polyols helps to improve the weather resistance of polyurethane adhesives; and the prepared polyurethane adhesive prepolymer presents a comb-shaped structure, and after curing and cross-linking, it presents a stable cross-linked network structure, which further improves its weather resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The present invention is a process flow chart of an embodiment of a method for preparing a highly weather-resistant and yellowing-resistant polyurethane adhesive.

[0021] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0022] To make the purpose, technical scheme and advantages of the embodiment of the present invention clearer, the technical scheme in the embodiment of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiment, it is carried out according to the normal conditions or the conditions recommended by the manufacturer. If the reagents or instruments used do not specify the manufacturer, they are all conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes, taking "A and / or B" as an example, including scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that the combination of such technical solutions does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present invention.

[0023] At present, there are two main methods to improve the yellowing resistance of polyurethane. One is to add anti-yellowing agents, light stabilizers, etc. Although this method can achieve a certain anti-yellowing effect, it can only temporarily delay the yellowing time, and the actual effect is limited; moreover, the large amount of anti-yellowing additives will affect the mechanical properties of polyurethane materials. The second is to use aliphatic / alicyclic isocyanates to replace aromatic isocyanates, such as isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI) or hexamethylene diisocyanate (HDI). Aliphatic or alicyclic isocyanates do not contain aromatic rings in their molecular structure, which fundamentally solves the problem of yellowing of polyurethane materials; however, aliphatic or alicyclic isocyanates do not have the conjugation effect of benzene rings, have low reaction activity, extremely slow reaction rate, and high toxicity during the production process; moreover, the mechanical properties, water resistance, and solvent resistance of the prepared polyurethane materials are poor, especially its light aging performance is much lower than that of polyurethane materials prepared with aromatic isocyanates. Therefore, sports fields paved with polyurethane adhesives based on aliphatic or alicyclic isocyanates are prone to aging and becoming sticky.

[0024] In view of this, the present invention proposes a highly weather-resistant and yellowing-resistant polyurethane adhesive and a preparation method and application thereof, in order to solve the problem that the existing yellowing-resistant polyurethane adhesive cannot fundamentally solve the weathering problem, which either requires the addition of an anti-yellowing agent, but the anti-yellowing time is short and the effect is average; or an aliphatic / alicyclic isocyanate is used, but the reaction activity is low, the toxicity is still high during the production process, and the resulting polyurethane material has poor weather resistance. The invention provides a highly weather-resistant and yellowing-resistant polyurethane adhesive, which comprises the following raw materials in parts by weight: based on 10 parts of isocyanate, 72-457 parts of polymer polyol, 36-111 parts of isocyanate oligomer, 30-385 parts of polyacrylate polyol, 15-191 parts of plasticizer and 0.8-9.5 parts of catalyst, wherein the isocyanate comprises at least one of aliphatic isocyanate and alicyclic isocyanate; the polymer polyol comprises polycarbonate diol, and the molecular weight of the polycarbonate diol is 1000-4000; the isocyanate oligomer comprises an addition product of aliphatic isocyanate and / or alicyclic isocyanate and trimethylolpropane; the molecular weight of the polyacrylate polyol is 4000-8000, and the hydroxyl value of the polyacrylate polyol is 28-56 mg KOH / g.

[0025] The isocyanate used in the present invention is an aliphatic and / or alicyclic isocyanate and its adduct, and no anti-yellowing agent or light stabilizer is added, which can completely solve the yellowing problem of polyurethane. In the embodiment of the present invention, an excess of polycarbonate polyol is reacted with aliphatic / alicyclic isocyanate, assisted by a small amount of catalyst, so that the isocyanate of the low-activity aliphatic / alicyclic isocyanate is completely reacted to obtain a hydroxyl-terminated polyurethane prepolymer, which solves the problem of low activity and incomplete reaction of aliphatic and / or alicyclic isocyanate; then, an excess of isocyanate oligomer is reacted with the hydroxyl-terminated polyurethane prepolymer to obtain an isocyanate-terminated polyurethane prepolymer; and finally, polyacrylate polyol is used for chain extension to obtain a polyurethane adhesive.

[0026] It should be noted that, by adopting the above technical solution, on the one hand, the polymerization process and raw materials are adjusted to make the aliphatic or alicyclic isocyanate react completely, thereby improving the aging performance of the polyurethane. On the other hand, the polyacrylate chain segment is introduced through the chain extension reaction of the polyacrylate polyol, which helps to improve the weather resistance of the polyurethane adhesive; and the prepared polyurethane adhesive prepolymer presents a comb-shaped structure, and after curing and cross-linking, it presents a stable cross-linked network structure, which further improves its weather resistance.

[0027] Furthermore, the isocyanate includes at least one of aliphatic isocyanate and alicyclic isocyanate.

[0028] It should be noted that compared with aromatic isocyanates, the aliphatic and / or alicyclic isocyanates used this time do not contain aromatic rings or the conjugation effect of benzene rings in their molecular structures, and do not have yellowing properties, which completely solves the yellowing property of aromatic polyurethanes.

[0029] Specifically, the isocyanate can be hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, methylcyclohexyl diisocyanate or cyclohexyl diisocyanate. The selected isocyanate is mainly alicyclic isocyanate, which is beneficial to improve the reactivity of isocyanate and also helps to improve the mechanical properties of polyurethane adhesive. At the same time, in order to improve the flexibility of polyurethane adhesive, aliphatic isocyanate hexamethylene diisocyanate can also be used in whole or in part.

[0030] Furthermore, the polymer polyol includes polycarbonate diol, and the molecular weight of the polycarbonate diol is 1000-4000.

[0031] Specifically, the molecular weight of the polycarbonate diol may be 1000, 2000, or 4000. Although the low molecular weight polycarbonate diol has high activity of hydroxyl groups, the flexibility of the polyurethane adhesive is poor; if the molecular weight of the polycarbonate diol is too high (greater than 4000), the reactivity of the hydroxyl groups is low, which is not conducive to the reaction with low-activity aliphatic / alicyclic isocyanates, and the mechanical strength of the obtained polyurethane adhesive is reduced, so the molecular weight of the polycarbonate diol is preferably in the range of 1000 to 4000.

[0032] Further, in some embodiments of the present application, the isocyanate oligomer is an addition product of aliphatic isocyanate and / or alicyclic isocyanate and trimethylolpropane. In some embodiments of the present application, the isocyanate oligomer may also contain a mixture of addition products of different isocyanates and trimethylolpropane, wherein the different isocyanates include at least one of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and isophorone diisocyanate. Aliphatic isocyanate and / or alicyclic isocyanate and trimethylolpropane are reacted by polyaddition to obtain a trifunctional isocyanate oligomer product, which is beneficial to the reaction of isocyanate with terminal hydroxyl polyurethane prepolymer to obtain a multifunctional terminal isocyanate polyurethane prepolymer. Moreover, the isocyanate oligomer of the present invention does not contain a benzene ring, and the obtained polyurethane adhesive does not yellow. The structural formula of the isocyanate oligomer is as follows, wherein R is a molecular group of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate, respectively:

[0033]

[0034] Furthermore, the molecular weight of the polyacrylate polyol is 4000-8000, and the hydroxyl value of the polyacrylate polyol is 28-56 mg KOH / g. The functionality can be calculated by the molecular weight and the hydroxyl value, for example: 4000 molecular weight, hydroxyl value of 28 mg KOH / g, with 2 functionality; hydroxyl value of 56 mg KOH / g, with 4 functionality; 8000 molecular weight, hydroxyl value of 28 mg KOH / g, with 4 functionality; hydroxyl value of 56 mg KOH / g, with 8 functionality. Through the chain extension effect of polyacrylate polyol, the introduction of polyacrylate chain segments into the polyurethane molecular chain helps to improve the weather resistance of the polyurethane adhesive. At the same time, the flexibility of the polyurethane adhesive is adjusted by adjusting the molecular weight of the polyacrylate polyol. If the molecular weight is too low, the flexibility of the polyurethane adhesive is poor; if the molecular weight is too high, the reactivity of the polyacrylate polyol is low. In addition, the polyurethane adhesive obtained by chain extension of polyacrylate polyol has a comb-shaped structure. The functionality of polyacrylate polyol mainly affects the cross-linking degree of polyurethane adhesive, thereby affecting its mechanical properties and weather resistance. If the functionality is too low, its cross-linking degree and cross-linking density are low, and its mechanical properties and weather resistance are poor; if the functionality is too high, its cross-linking degree is high, which is beneficial to improve the mechanical properties and weather resistance of polyurethane adhesive, but its flexibility is poor.

[0035] Further, the plasticizer includes at least one of dibutyl phthalate and dioctyl phthalate; and / or, the catalyst includes an organic metal compound, and the organic metal compound includes at least one of stannous isooctanoate, stannous octoate, dibutyltin dilaurate and dibutyltin dichloride.

[0036] Specifically, the plasticizer in the present invention can be dibutyl phthalate, dioctyl phthalate, or a mixture of the two. Adding a plasticizer can increase the plasticity of the polyurethane adhesive, reduce viscosity, and increase fluidity; and the catalyst in the present invention uses an organic metal compound, which helps to increase the reactivity of aliphatic / alicyclic isocyanates with hydroxyl groups and promote the reaction of isocyanates; when the polyurethane adhesive is cured, it helps to increase its wet curing reaction rate, so that the isocyanate groups in the comb-shaped polyurethane prepolymer finally obtained react with water in the air to cure and form.

[0037] The present invention also provides a method for preparing the highly weather-resistant and yellowing-resistant polyurethane adhesive as described above, which is used to prepare the highly weather-resistant and yellowing-resistant polyurethane adhesive as described above. Figure 1 , Figure 1 The process flow chart of an embodiment of a method for preparing a highly weather-resistant and yellowing-resistant polyurethane adhesive of the present invention comprises the following steps:

[0038] S10, dehydrating 72 to 457 parts of polymer polyol under reduced pressure at 95 to 115° C., mixing with 10 parts of isocyanate and 0.4 to 4.8 parts of catalyst, reacting at 70 to 90° C. for 3 to 6 hours, and cooling to obtain hydroxyl-terminated polyurethane prepolymer A;

[0039] S20, mixing the hydroxyl-terminated polyurethane prepolymer A with 36 to 111 parts of isocyanate oligomer, reacting at 60 to 85° C. for 2 to 5 hours, and cooling to obtain a polyurethane prepolymer B;

[0040] S30, dehydrating 30 to 385 parts of polyacrylate polyol under reduced pressure at 95 to 115° C., reacting with polyurethane prepolymer B at 55 to 80° C. for 2 to 4 hours, and cooling to obtain polyurethane prepolymer C;

[0041] S40, dehydrating 15 to 191 parts of plasticizer under reduced pressure at 95 to 105° C., mixing with the polyurethane prepolymer C at room temperature, and adding the remaining catalyst; stirring and mixing evenly, and degassing to obtain a highly weather-resistant and yellowing-resistant polyurethane adhesive.

[0042] In some embodiments, S10, dehydrating 72 to 457 parts of polymer polyol under reduced pressure at 95 to 115° C., mixing with 10 parts of isocyanate and 0.4 to 4.8 parts of catalyst, reacting at 70 to 90° C. for 3 to 6 hours, and cooling to obtain a hydroxyl-terminated polyurethane prepolymer A;

[0043] It should be noted that aliphatic / alicyclic isocyanates have low activity, and a polymer polyol with a certain molecular weight and a certain activity is selected; an excess polymer polyol is reacted with a small amount of aliphatic / alicyclic isocyanate, assisted by a small amount of catalyst, and the reaction temperature is adjusted to allow the isocyanate to react completely to form a hydroxyl (-OH) terminated oligomer A; in some embodiments, the polyurethane oligomer A obtained after the reaction presents a linear structure, and the reaction formula is as follows:

[0044]

[0045] It should be noted that the polymer polyol reacts with the isocyanate group to form a polyurethane, which is a flexible segment of the polyurethane molecule, and the rigid segment is carbamate (-NHCOO-); the higher the molecular weight of the polymer polyol, the longer the flexible segment, and the better the flexibility of the polyurethane molecule. However, due to the low activity of the hydroxyl group of the polymer polyol molecule, the larger the molecular weight, the lower the activity, and the low activity of the aliphatic / alicyclic isocyanate group; (1) the mutual reaction rate between the two is low and it is difficult to react completely; (2) Increasing the temperature can increase the reaction rate, but an isomerization reaction will occur.

[0046] S20, mixing the hydroxyl-terminated polyurethane prepolymer A with 36 to 111 parts of isocyanate oligomer, reacting at 60 to 85° C. for 2 to 5 hours, and cooling to obtain a polyurethane prepolymer B;

[0047] In some embodiments, an excess of isocyanate oligomer is added to polyurethane oligomer A, supplemented with a small amount of catalyst, and the reaction temperature is adjusted to allow the hydroxyl groups in polyurethane oligomer A to react completely, thereby obtaining a polyurethane prepolymer B terminated with a multifunctional isocyanate group, and the chain segments after the reaction are extended. The specific reaction formula is as follows:

[0048]

[0049] S30, dehydrating 30 to 385 parts of polyacrylate polyol under reduced pressure at 95 to 115° C., reacting with polyurethane prepolymer B at 55 to 80° C. for 2 to 4 hours, and cooling to obtain polyurethane prepolymer C;

[0050] It should be noted that the excess isocyanate groups of the polyurethane prepolymer B react with a small amount of hydroxyl groups of the polyacrylate polyol to extend and branch the molecular chain to obtain a dendritic polyurethane prepolymer with isocyanate groups as the terminal groups.

[0051] In some embodiments, the reaction formula is as follows:

[0052]

[0053] S40, dehydrating 15 to 191 parts of plasticizer under reduced pressure at 95 to 105° C., mixing with the polyurethane prepolymer C at room temperature, and adding the remaining catalyst; stirring and mixing evenly, and degassing to obtain a highly weather-resistant and yellowing-resistant polyurethane adhesive.

[0054] It should be noted that the plasticizer increases plasticity, reduces viscosity, and increases fluidity; the catalyst catalyzes the wet curing reaction rate of the isocyanate group. Finally, when the adhesive is used, the isocyanate group in the obtained branched polyurethane prepolymer reacts with water in the air to cure (i.e., warm curing).

[0055] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0056] Example 1

[0057] A highly weather-resistant and yellowing-resistant polyurethane adhesive, comprising the following raw materials in parts by weight: 10 parts of dicyclohexylmethane diisocyanate, 72 parts of polycarbonate diol (molecular weight of 1000), 36 parts of hexamethylene diisocyanate oligomer, 30 parts of polyacrylate polyol (molecular weight of 6000, hydroxyl value of 56 mg KOH / g), 52 parts of dioctyl phthalate and 2.4 parts of stannous octoate;

[0058] A method for preparing a highly weather-resistant and yellowing-resistant polyurethane adhesive, using the components of Example 1, comprises the following steps:

[0059] S10, dehydrating 72 parts of polycarbonate diol at 105° C., mixing with 10 parts of dicyclohexylmethane diisocyanate and 1.2 parts of stannous octoate, reacting at 70° C. for 6 hours, and cooling to obtain a hydroxyl-terminated polyurethane prepolymer A;

[0060] S20, mixing the hydroxyl-terminated polyurethane prepolymer A with 36 parts of hexamethylene diisocyanate oligomer, reacting at 70° C. for 3 hours, and cooling to obtain a hydroxyl-terminated polyurethane prepolymer B;

[0061] S30, reacting 30 parts of polyacrylate polyol with the hydroxyl-terminated polyurethane prepolymer B at 65° C. for 4 hours after dehydration under reduced pressure at 95° C., and cooling to obtain polyurethane prepolymer C;

[0062] S40, dehydrating 52 parts of dibutyl phthalate under reduced pressure at 95° C., mixing the mixture with the polyurethane prepolymer C, adding the remaining stannous octoate, stirring and mixing, and degassing to obtain a highly weather-resistant and yellowing-resistant polyurethane adhesive.

[0063] Example 2-22

[0064] Example 2-22 is similar to Example 1, except that the ratio of the highly weather-resistant and yellowing-resistant polyurethane adhesive is different, please see Table 1 for details.

[0065] Table 1 Components and proportions of highly weather-resistant and yellowing-resistant polyurethane adhesives in Example 2-22

[0066]

[0067]

[0068] Comparative Example 1

[0069] The difference from Example 5 is that in step S10, the polycarbonate diol with a molecular weight of 2000 is replaced with a polyether diol with a molecular weight of 2000.

[0070] Comparative Example 2

[0071] Different from Example 5, in step S10, the molecular weight of the polycarbonate diol is 800 and the amount used is 58 parts.

[0072] Comparative Example 3

[0073] Different from Example 5, in step S10, the molecular weight of the polycarbonate diol is 4500 and the amount used is 326 parts.

[0074] Comparative Example 4

[0075] The difference from Example 5 is that in step S10, the amount of polycarbonate diol with a molecular weight of 2000 is 70 parts.

[0076] Comparative Example 5

[0077] Different from Example 5, in step S10, the amount of polycarbonate diol with a molecular weight of 2000 is 460 parts.

[0078] Comparative Example 6

[0079] The difference from Example 5 is that in step S10, 10 parts of dicyclohexylmethane diisocyanate are replaced by 9.5 parts of diphenylmethane diisocyanate.

[0080] Comparative Example 7

[0081] The difference from Example 5 is that in step S20, the amount of hexamethylene diisocyanate oligomer is 34 parts.

[0082] Comparative Example 8

[0083] The difference from Example 5 is that in step S20, the amount of hexamethylene diisocyanate oligomer is 115 parts.

[0084] Comparative Example 9

[0085] Different from Example 5, in step S30, the molecular weight of the polyacrylate polyol is 8500, and the hydroxyl value is 28 mgKOH / g.

[0086] Comparative Example 10

[0087] Different from Example 5, in step S30, the molecular weight of the polyacrylate polyol is 3500, and the hydroxyl value is 28 mgKOH / g.

[0088] Comparative Example 11

[0089] Different from Example 5, in step S30, the molecular weight of the polyacrylate polyol is 6000, and the hydroxyl value is 25 mgKOH / g.

[0090] Comparative Example 12

[0091] The difference from Example 5 is that in step S30, the molecular weight of the polyacrylate polyol is 6000, and the hydroxyl value is 60 mgKOH / g.

[0092] Comparative Example 13

[0093] The difference from Example 5 is that in step S30, the amount of polyacrylate polyol used is 28 parts.

[0094] Comparative Example 14

[0095] The difference from Example 5 is that in step S30, the amount of polyacrylate polyol used is 388 parts.

[0096] The polyurethane adhesive prepared by the present invention is applied to sports venue composite materials, and its tensile strength (non-permeable surface layer), elongation at break, impact absorption (track and field venue), vertical deformation, and aging resistance are analyzed according to the standard of GB 36246-2018 "Synthetic material surface layer sports venues for primary and secondary schools"; wherein, its aging resistance is subjected to a xenon lamp irradiation test according to the provisions of GB / T 16422.2-2013, and the test conditions are method A, cycle number 1, and after 500 hours of testing, the tensile strength and elongation at break are measured, and its yellowing performance is determined according to the determination of discoloration (yellowing) performance of adhesives in GB / T 39294-2020. The test results of the polyurethane adhesives obtained in the embodiments and comparative examples are shown in Tables 2 and 3.

[0097] Table 2 Test results of highly weather-resistant and yellowing-resistant polyurethane adhesive (Example)

[0098]

[0099] From the test results of the embodiment in Table 2, it can be seen that:

[0100] (1) In the comparison of Example 1, Example 2 and Example 3, as the molecular weight of the polycarbonate diol increases, the flexibility of the adhesive increases, and its tensile strength decreases before and after aging, the elongation at break increases first and then decreases, and the impact absorption and vertical deformation increase;

[0101] (2) Compared with Example 2, the molecular weight of the polyacrylate polyol in Examples 4 and 5 remains unchanged, but its hydroxyl value is reduced, the functionality of the polyacrylate polyol is reduced, the degree of crosslinking of the obtained polyurethane adhesive is reduced, and its tensile strength, elongation at break and impact absorption before and after aging are reduced, and the vertical deformation is increased;

[0102] (3) In the comparison of Example 6, Example 4 and Example 7, the hydroxyl value of the polyacrylate polyol remains unchanged, its molecular weight increases, the functionality increases, the crosslinking degree of the obtained polyurethane adhesive increases, and its tensile strength increases before and after aging, but the elongation at break, impact absorption and vertical deformation all decrease;

[0103] (4) Compared with Example 4, the molecular weight and hydroxyl value of the polyacrylate polyol in Examples 8 and 9 remain unchanged, but the amount thereof is gradually increased, the crosslinking degree of the obtained polyurethane adhesive increases, the tensile strength and elongation at break of the adhesive increase before and after aging, the vertical deformation decreases, but the impact absorption increases;

[0104] (5) Compared with Example 8, in Examples 10 and 11, different isocyanate oligomers have a certain influence on the polyurethane adhesive. Among them, the polyurethane adhesive based on dicyclohexylmethane diisocyanate oligomer has better performance in all aspects before and after aging, while the polyurethane adhesive based on hexamethylene diisocyanate oligomer has poorer performance before and after aging;

[0105] (6) Compared with Example 11, the increase in the content of dicyclohexylmethane isocyanate oligomers in Examples 12 and 13 increased the tensile strength of the polyurethane adhesive, but the elongation at break and the impact absorption first increased and then decreased, and the vertical deformation decreased; however, the excessively high content of dicyclohexylmethane isocyanate oligomers caused the tensile strength to decrease after aging, and the vertical deformation to increase;

[0106] (7) Compared with Example 12, the diisocyanate in Examples 14, 15, 16, and 17 was changed, and the properties of the obtained polyurethane adhesives were different. The polyurethane adhesive based on dicyclohexylmethane diisocyanate had better performance before and after aging, and the polyurethane adhesive based on hexamethylene diisocyanate had a deviation in performance;

[0107] (8) Compared with Example 17, the increase in the content of dicyclohexylmethane diisocyanate oligomers in Example 18 increased the tensile strength of the polyurethane adhesive before and after aging, while the elongation at break, vertical deformation, and impact absorption decreased;

[0108] (9) Compared with Example 18, the molecular weight of the polycarbonate diol in Example 19 is increased, the flexibility of the adhesive is enhanced, the tensile strength decreases and the elongation at break increases before and after aging, and the impact absorption and vertical deformation also increase;

[0109] (10) Compared with Example 19, the molecular weight and hydroxyl value of the polyacrylate polyol in Example 20 remain unchanged, but its dosage increases, and the tensile strength of the adhesive increases before and after aging, while the elongation at break, vertical deformation and impact absorption decrease;

[0110] (11) Compared with Example 20, the molecular weight of polyacrylate polyol in Example 21 remains unchanged, the hydroxyl value decreases, and the functionality of polyacrylate polyol decreases; however, its dosage increases, and the hydroxyl number of polyacrylate polyol does not change. The crosslinking density of the obtained polyurethane adhesive decreases, and the tensile strength of the adhesive before and after aging decreases, while the elongation at break, impact absorption, and vertical deformation increase;

[0111] (12) Compared with Example 21, the amount of plasticizer and catalyst used in Example 22 is increased. The catalyst mainly affects the reaction and curing rate, and the plasticizer is mainly used to adjust the viscosity and has the effect of increasing flexibility. As the content of plasticizer increases, the mechanical properties and impact absorption of the polyurethane adhesive before and after aging decrease, and the vertical deformation increases.

[0112] The performance of the polyurethane adhesive obtained in Examples 1-22 before and after aging meets the national standards, the color difference is within 0.15, and it has excellent weather resistance and yellowing resistance.

[0113] The test results of the polyurethane adhesive obtained in the comparative example are shown in Table 3.

[0114] Table 3 Test results of highly weather-resistant and yellowing-resistant polyurethane adhesive (Comparative Example)

[0115]

[0116] From Table 3, we can see that:

[0117] In Comparative Example 1, the polycarbonate diol with a molecular weight of 2000 was replaced with a polyether diol with a molecular weight of 2000. The mechanical strength of the adhesive decreased, the elongation at break increased, and the impact absorption and vertical deformation increased. After aging, the impact absorption and vertical deformation did not meet the standards, and the color difference ΔE increased, showing a certain yellowing property.

[0118] In Comparative Examples 2 and 3, the molecular weight of the polycarbonate diol is too low, the flexibility of the adhesive is poor, and its impact absorption after aging does not meet the standard; the molecular weight of the polycarbonate diol is too high, although the flexibility of the adhesive is good, its vertical deformation is high, especially after aging, the mechanical strength and vertical deformation of the adhesive do not meet the standard;

[0119] In Comparative Examples 4 and 5, the amount of polycarbonate diol used is too low, the rigidity of the adhesive is enhanced, but the toughness is poor, and the elongation at break and impact absorption of the adhesive after aging do not meet the standards; the amount of polycarbonate diol used is too high, and the curing and cross-linking of the adhesive is insufficient, resulting in reduced tensile strength and impact absorption and increased vertical deformation. After aging, the tensile strength, impact absorption and vertical deformation of the adhesive do not meet the standards;

[0120] In Comparative Example 6, the aliphatic dicyclohexylmethane diisocyanate was replaced with aromatic diphenylmethane diisocyanate, and its mechanical properties, impact absorption, and vertical deformation were better than those of the adhesive prepared by the aliphatic dicyclohexylmethane diisocyanate, but it was prone to yellowing and had a high color difference ΔE after aging;

[0121] In Comparative Examples 7 and 8, the dosage of hexamethylene diisocyanate oligomer is too low, and the curing and crosslinking of the adhesive is insufficient, resulting in reduced mechanical properties and impact absorption, increased vertical deformation, and after aging, its tensile strength, impact absorption, and vertical deformation do not meet the standards; the dosage of hexamethylene diisocyanate oligomer is too high, the rigidity of the adhesive is enhanced, but the toughness is poor, and after aging, its elongation at break and impact absorption do not meet the standards;

[0122] In Comparative Examples 9 and 10, the molecular weight of the polyacrylate polyol is too high, the crosslinking density is reduced, and the mechanical properties are reduced, but its impact absorption and vertical deformation are increased, and its vertical deformation does not meet the standards after aging; the molecular weight of the polyacrylate polyol is too low, the crosslinking density is increased, the mechanical properties of the adhesive are increased, but its impact absorption and vertical deformation are reduced, and its impact absorption does not meet the standards after aging.

[0123] In Comparative Examples 11 and 12, the hydroxyl value of the polyacrylate polyol is too low, the crosslinking degree of the polyurethane is too low, the tensile strength of the obtained polyurethane adhesive decreases, and although the elongation at break, impact absorption, and vertical deformation increase, the performance indicators of the adhesive after aging do not meet the standards; the hydroxyl value of the polyacrylate polyol is too high, and the crosslinking degree of the polyurethane is high. Although the mechanical strength of the adhesive is high and the vertical deformation is small, its elongation at break and impact absorption are still low, and after aging, its elongation at break and impact absorption do not meet the standards.

[0124] In Comparative Examples 13 and 14, the amount of polyacrylate polyol used is too low, the crosslinking degree of the polyurethane is too low, the tensile strength of the obtained polyurethane adhesive has dropped below the standard, the elongation at break has also decreased, the vertical deformation has increased, and especially after aging, all of its indicators do not meet the standards; the amount of polyacrylate polyol used is too high, the crosslinking degree of the polyurethane is high, the mechanical strength of the adhesive is improved, the vertical deformation is small, but the impact absorption is lower than the standard; after aging, its elongation at break and impact absorption do not meet the standards.

[0125] It can be seen that among comparative examples 1-14, the polyurethane adhesive prepared by using aromatic isocyanate in comparative example 6 has a large color difference ΔE and is prone to yellowing; some or all of the performance indicators of the polyurethane adhesives obtained in other comparative examples before and after aging do not meet the standards.

[0126] The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the patent protection scope of the present invention.

Claims

1. A highly weather-resistant and yellowing-resistant polyurethane adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: based on 10 parts of isocyanate, 72 to 457 parts of polymer polyol, 36 to 111 parts of isocyanate oligomer, 30 to 385 parts of polyacrylate polyol, 15 to 191 parts of plasticizer and 0.8 to 9.5 parts of catalyst, wherein: The isocyanate includes at least one of an aliphatic isocyanate and an alicyclic isocyanate; The polymer polyol includes polycarbonate diol, and the molecular weight of the polycarbonate diol is 1000 to 4000; The isocyanate oligomer includes an addition product of aliphatic isocyanate and / or alicyclic isocyanate and trimethylolpropane; The molecular weight of the polyacrylate polyol is 4000-8000, and the hydroxyl value of the polyacrylate polyol is 28-56 mg KOH / g.

2. The highly weather-resistant and yellowing-resistant polyurethane adhesive according to claim 1, characterized in that: The isocyanate includes at least one of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, methylcyclohexyl diisocyanate and cyclohexyl diisocyanate.

3. The highly weather-resistant and yellowing-resistant polyurethane adhesive according to claim 1, characterized in that: The isocyanate oligomer includes at least one of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and an addition product of isophorone diisocyanate and trimethylolpropane.

4. The highly weather-resistant and yellowing-resistant polyurethane adhesive according to claim 1, characterized in that: The plasticizer includes at least one of dibutyl phthalate and dioctyl phthalate; and / or, The catalyst comprises an organic metal compound, and the organic metal compound comprises at least one of stannous isooctanoate, stannous octoate, dibutyltin dilaurate and dibutyltin dichloride.

5. A method for preparing a highly weather-resistant and yellowing-resistant polyurethane adhesive, for preparing the highly weather-resistant and yellowing-resistant polyurethane adhesive as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: S10, dehydrating 72 to 457 parts of polymer polyol under reduced pressure at 95 to 115° C., mixing with 10 parts of isocyanate and 0.4 to 4.8 parts of catalyst, reacting at 70 to 90° C. for 3 to 6 hours, and cooling to obtain hydroxyl-terminated polyurethane prepolymer A; S20, mixing the hydroxyl-terminated polyurethane prepolymer A with 36 to 111 parts of isocyanate oligomer, reacting at 60 to 85° C. for 2 to 5 hours, and cooling to obtain a polyurethane prepolymer B; S30, dehydrating 30 to 385 parts of polyacrylate polyol under reduced pressure at 95 to 115° C., reacting with polyurethane prepolymer B at 55 to 80° C. for 2 to 4 hours, and cooling to obtain polyurethane prepolymer C; S40, dehydrating 15 to 191 parts of plasticizer under reduced pressure at 95 to 105° C., mixing with the polyurethane prepolymer C at room temperature, and adding the remaining catalyst; stirring and mixing evenly, and degassing to obtain a highly weather-resistant and yellowing-resistant polyurethane adhesive.

6. A composite material for sports fields, characterized in that: The composite material comprises a highly weather-resistant and yellowing-resistant polyurethane adhesive, wherein the highly weather-resistant and yellowing-resistant polyurethane adhesive is the highly weather-resistant and yellowing-resistant polyurethane adhesive as described in any one of claims 1 to 4 or the highly weather-resistant and yellowing-resistant polyurethane adhesive prepared by the preparation method of the highly weather-resistant and yellowing-resistant polyurethane adhesive as claimed in claim 5.

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