A moisture-curing polyurethane hot melt adhesive containing polycarbonate polyether polyol

Abstract

The invention discloses a moisture-curing polyurethane hot melt adhesive containing polycarbonate polyether polyol, and belongs to the technical field of adhesive synthesis. The moisture-curing polyurethane hot melt adhesive containing polycarbonate polyether polyol provided by the invention is mainly made of the following raw materials in parts by weight: 65-95 parts by weight of polyurethane prepolymer, 5-30 parts by weight of modifier, and 0.2-5 parts by weight of auxiliary agent. The invention discloses the preparation of a moisture-curing polyurethane hot melt adhesive containing polycarbonate polyether polyol, which has the properties of energy saving and environmental protection, wide material selection, good compatibility, high adhesion, etc., and is suitable for promotion and application.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesive synthesis, and in particular relates to a moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol. Background Art

[0002] Moisture-curing polyurethane hot melt adhesive is widely used in the bonding of metal, wood, paper, plastic and other materials due to its advantages of environmental protection, fast bonding speed, high bonding strength, wide range of substrate applications and high cost performance. With the continuous deepening of my country's industrialization process, this kind of moisture-curing polyurethane hot melt adhesive has become more and more widely used and its usage is increasing. According to incomplete statistics, the usage of polyurethane hot melt adhesive in 2018 increased by more than 40% compared with 2017, which is much higher than other types of hot melt adhesive or adhesive products. It can be seen that high-grade moisture-curing polyurethane hot melt adhesive will play an important role in my country's industrialization process.

[0003] At present, moisture-curing polyurethane hot melt adhesives are mostly prepared by mixing polyester polyols and polyether polyols, and the performance of each hot melt adhesive is adjusted by different ratios of the two. However, during the research and development process, we found that polyester polyols and polyether polyols are incompatible, and the mixture of the two is milky white and non-transparent, especially when mixed with polyether polyols with trifunctionality or above, the incompatibility of the two is very obvious. As a result, the color of the hot melt adhesive is non-transparent. Although the color of the hot melt adhesive has little correlation with the performance of the hot melt adhesive, in actual use, the transparency of the hot melt adhesive directly affects the user experience, especially the visual requirements of the appearance. Summary of the invention

[0004] In response to the problems of poor solubility and poor mechanical properties of existing moisture-curing polyurethane hot melt adhesives, we found that polycarbonate polyether polyols have both polycarbonate and polyether functionalities, and the polycarbonate group has excellent solubility with polyester. Therefore, we took advantage of the good solubility of polycarbonate polyether polyols with polyester polyols and polyether polyols, and used them as "surfactants" to obtain moisture-curing polyurethane hot melt adhesives with good solubility and mechanical properties.

[0005] One of the purposes of the present invention is to provide a moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol, which has good environmental protection and fast curing, can be widely used in the bonding fields of furniture, woodworking, textiles, shoemaking, packaging, automobile transportation, etc., and is suitable for promotion and application.

[0006] One of the objects of the present invention is to provide a method for preparing a moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] In the first aspect, a moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol is provided, which comprises the following raw materials, in parts by weight: 65-95 parts by weight of a polyurethane prepolymer, for example, 65 parts by weight, 68 parts by weight, 69 parts by weight, 70 parts by weight, 72 parts by weight, 74 parts by weight, 76 parts by weight, 78 parts by weight, 80 parts by weight, 82 parts by weight, 84 parts by weight, 86 parts by weight, 88 parts by weight, 90 parts by weight, 95 parts by weight, preferably 75-90 parts by weight; 5-30 parts by weight of a modifier, for example, 5 parts by weight, 7 parts by weight, 9 parts by weight, 12 parts by weight, 14 parts by weight, 16 parts by weight, 18 parts by weight, 20 parts by weight, 22 parts by weight, 0.2-5 weight parts of auxiliary agent, for example 0.2 weight parts, 0.4 weight parts, 0.6 weight parts, 0.8 weight parts, 1.0 weight parts, 1.2 weight parts, 1.4 weight parts, 1.6 weight parts, 1.8 weight parts, 2.0 weight parts, 2.2 weight parts, 2.4 weight parts, 2.6 weight parts, 2.8 weight parts, 3.0 weight parts, 3.2 weight parts, 3.4 weight parts, 3.6 weight parts, 3.8 weight parts, 4.0 weight parts, 4.2 weight parts, 4.4 weight parts, 4.6 weight parts, 4.8 weight parts, 5.0 weight parts, preferably 3-4 weight parts.

[0009] The polyurethane prepolymer is obtained by reacting a polyol with an excess of isocyanate;

[0010] The polyol is selected from a combination of a polyester polyol and a polycarbonate polyether polyol, or a combination of a polyether polyol and a polycarbonate polyether polyol, or a combination of a polyester polyol, a polyether polyol and a polycarbonate polyether polyol;

[0011] The mass ratio of the polycarbonate polyether polyol to the polyol in the mixture is not less than 3%.

[0012] The dosage of polyester polyol and polyether polyol can be adjusted according to actual needs, and the present invention does not impose any limitation thereto.

[0013] The following is a detailed description of each raw material:

[0014] Polyurethane prepolymer

[0015] Polyurethane prepolymers are obtained by reacting polyols with excess isocyanate.

[0016] The specific reaction of the polyol and the excess isocyanate is as follows: after removing water from the polyol and cooling it, isocyanate is added and stirred to obtain a polyurethane prepolymer;

[0017] Preferably, the stirring further includes a defoaming treatment.

[0018] Specifically, the polyol dehydration and cooling is to heat the polyol to 100-130° C. and vacuum dehydration, with a vacuum degree of -0.09 MPa to -0.1 MPa, and a vacuum holding time of more than 0.5 h; the dehydration requirement is to detect a moisture content of less than 500 ppm.

[0019] The cooling temperature is 40-100°C.

[0020] The stirring time is 0.5-1.2h, and the stirring rate is 100-500r / min.

[0021] It should be noted that the stirring time after adding isocyanate can also be determined according to the theoretical value of NCO%.

[0022] Specifically, NCO% is the content of isocyanate in 100g of sample. Theoretical value NCO% = (number of moles of isocyanate - number of moles of hydroxyl - number of moles of water x 2) x 42 / total mass.

[0023] Wherein, the defoaming is carried out in a vacuum at 60-150°C.

[0024] Specifically, the degassing treatment is performed by using a vacuum.

[0025] Among them, the vacuum degree of vacuum degassing is between -0.09MPa and -0.1MPa, and the vacuum time is more than 0.5h.

[0026] Polycarbonate Polyether Polyol

[0027] Polycarbonate polyether polyol is a block copolymer of polycarbonate and polyether, which can be represented by the following formula:

[0028] H-(-O-R1-O-CO-) m -(-O-R2-) n -OH.

[0029] Wherein: R1 and R2 are alkyl groups, m and n are the number of polycarbonate units and polyether units contained in each molecule, respectively. The values ​​of m and n can be used to determine a number of technical indicators such as the state of the polycarbonate polyether polyol (solid or liquid at room temperature), wherein the values ​​of m and n are both greater than 1, and the specific values ​​can be adjusted according to the actual requirements of the product, and the present invention does not impose any limitation thereto.

[0030] Preferably, the carbon raw material number of R1 or R2 in the polycarbonate polyether polyol does not exceed 5, preferably does not exceed 4. For example, it can be methylene, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl or isopentyl. R1 and R2 can be the same or different.

[0031] Polyester polyols

[0032] The polyester polyol can be a crystalline polyester polyol alone, or a mixture of a crystalline polyester polyol and a non-crystalline polyester polyol. The type and amount of the polyester polyol used are not limited, and all of them contain a large number of ester bonds, can form hydrogen bonds with water, and have a certain water absorption. The non-crystalline polyester polyol contains certain side groups (such as methyl, ethyl, etc.), which can theoretically lead to hydrophobicity, but under the premise that the content of amorphous polyester polyol generally does not exceed 10%, its hydrophobicity can be ignored.

[0033] Polyether polyols

[0034] The polyether polyol is an oligomer having an ether bond (—R—O—R—) in the main chain and more than two hydroxyl groups (—OH) in the terminal or side groups. Any one commonly used in the art can be used, and the type and amount of the polyester polyol used are not limited.

[0035] Isocyanate

[0036] Isocyanates are esters containing isocyanic acid.

[0037] Preferably, the isocyanate is one or more of diisocyanate or polyisocyanate.

[0038] Preferably, the isocyanate is a diisocyanate or a mixture of diisocyanates, such as one or more of diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), and lysine diisocyanate (LDI).

[0039] Modifier

[0040] The modifier may be any functional material known in the art that can improve the properties of the polyurethane prepolymer (such as melt viscosity, initial tack, etc.).

[0041] Preferably, the modifier is a mixture of one or more of vinyl acetate polymer, vinyl acetate and ethylene copolymer, acrylic polymer and its copolymer, and thermoplastic polyurethane polymer.

[0042] Additives

[0043] The auxiliary agent can be any material known in the art that can play a role in catalysis, leveling, anti-oxidation, curing, ultraviolet absorption, and deodorization.

[0044] Preferably, the auxiliary agent is a mixture of various auxiliary agents such as a catalyst, a leveling agent, an antioxidant, a latent curing agent, a UV absorber, and a deodorant.

[0045] Preferably, the catalyst is T12 and DMDEE, the leveling agent is BYK333, the antioxidant is 1010 and BHT, and the latent curing agent is an amino-terminated polyether type.

[0046] The term “comprising” as used in the present invention means that in addition to the aforementioned raw materials, other raw materials may also be included. In addition, the term “comprising” as used in the present invention may also be replaced by a closed form such as “for” or “consisting of…”, etc.

[0047] In a second aspect, a method for preparing a moisture-curable polyurethane hot melt adhesive containing a polycarbonate polyether polyol is provided, comprising the following steps:

[0048] S1. Add polyol into the container according to the raw material metering ratio, start heating, and start stirring after the material temperature reaches 100-130°C. The stirring speed is 200r / min, and the vacuum is more than 0.5h. The vacuum degree is between -0.09MPa and -0.1MPa. After the water content is detected to be less than 500ppm, stop the vacuum.

[0049] S2. Stop stirring, release the vacuum, cool to 80°C, add isocyanate, stir at 500r / min for 40min, and then test NCO%; then test NCO% every 30-60min until NCO% reaches the designed theoretical value ±0.2%;

[0050] S3. Add modifier and / or auxiliary agent according to the raw material metering ratio, and stir under vacuum for at least 30 minutes at a stirring speed of 100r / min and a vacuum degree between -0.09MPa and -0.1MPa. After the materials are mixed evenly without bubbles, they can be discharged, filled with nitrogen, and sealed for storage.

[0051] Preferably, in step S1, when adding polyol to the container according to the raw material metering ratio, a modifier and an auxiliary agent are added. It should be noted that the moisture-curing polyurethane hot melt adhesive provided by the present invention is obtained by adding a modifier and an auxiliary agent to a polyurethane prepolymer. The moisture-curing polyurethane hot melt adhesive of the present invention can be obtained by adding a modifier and an auxiliary agent while preparing the polyurethane prepolymer. For example, a modifier and an auxiliary agent are added when adding polyol, and for example, a modifier and an auxiliary agent are added after adding isocyanate and stirring, to obtain the moisture-curing polyurethane hot melt adhesive of the present invention.

[0052] The moisture-curable polyurethane hot melt adhesive provided by the present invention has at least the following beneficial effects:

[0053] Firstly, the moisture-curable polyurethane hot melt adhesive of the present invention is mainly composed of a polyurethane prepolymer, a modifier and an auxiliary agent. By using polycarbonate polyether polyol, the compatibility of polyester polyol and polyether polyol is increased. The most obvious benefit is that the appearance of the polyurethane hot melt adhesive is a transparent light yellow liquid. It is possible to identify the mixing of foreign matter, uneven stirring and other quality problems.

[0054] Secondly, by adopting polycarbonate polyether polyol, the moisture-curing polyurethane hot melt adhesive has a wider range of material selection, more flexible ratio, and a larger amount of trifunctional polyether polyol, and even the use of tetrafunctional and above polyether polyol becomes possible, thereby effectively improving the initial adhesion strength and the final adhesion strength. In particular, when trifunctional or above polyether polyol is used, the effect of improving the final adhesion strength is more obvious.

[0055] Finally, by using polycarbonate polyether polyol, according to different ratios, with the large amount of carbon-oxygen double bonds in polycarbonate, it has excellent water resistance, UV resistance, aging resistance and other properties. The polycarbonate polyether polyol used in the moisture-curing polyurethane hot melt adhesive of the present invention is also environmentally friendly and has a high curing speed. The synthesized hot melt adhesive can be used in the bonding fields of furniture, woodworking, textiles, shoemaking, packaging, automobile transportation, etc., and is suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 is a photograph of the hot melt adhesive prepared in Example 1 of the present invention;

[0057] Figure 2 This is a photo of the hot melt adhesive prepared in Comparative Example 1;

[0058] Figure 3 This is a photo of the hot melt adhesive prepared in Comparative Example 2. DETAILED DESCRIPTION

[0059] The present invention is further described below in conjunction with specific examples, but the present invention is not limited to the following examples. The methods are conventional methods unless otherwise specified. The raw materials can be obtained from public commercial channels unless otherwise specified. Obviously, the embodiments described are only part of the embodiments of the invention, not all of them. Unless otherwise specified, the materials in the embodiments are prepared according to existing methods or directly purchased from the market.

[0060] Examples 1-3 and Comparative Examples 1-2

[0061] A method for preparing a moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol, the proportions of Examples 1-3 and Comparative Examples 1-2 are shown in Table 1;

[0062] Table 1. Ingredients data sheet

[0063]

[0064] The latent curing agent can be prepared according to the method disclosed in Chinese patent document CN110698622A, entitled ketimine latent curing agent and reactive polyurethane hot melt adhesive having the same and application thereof.

[0065] Production method and process:

[0066] 1. Add raw materials No. 1, 2, 3, 5, 8, 9, 10 and 11 to the container in order according to the raw material metering ratio, start heating, and start stirring after the material temperature reaches 100-130℃. The stirring speed is 200r / min, and the vacuum is more than 0.5h. The vacuum degree is between -0.09MPa and -0.1MPa. After the moisture content is less than 500ppm, stop the vacuum.

[0067] 2. Stop stirring, release the vacuum, cool down to 80°C, add raw material No. 4, stir at 500r / min for 40min, then check NCO%; then check NCO% every 30-60min until NCO% reaches the designed theoretical value ±0.2%;

[0068] 3. Add raw materials No. 6 and 7 according to the raw material measurement ratio, and stir under vacuum for at least 30 minutes at a stirring speed of 100r / min and a vacuum degree between -0.09MPa and -0.1MPa. After the materials are mixed evenly without bubbles, they can be discharged, filled with nitrogen, and sealed for storage.

[0069] Table 2, Experimental data of Examples 1-3 and Comparative Examples 1-2

[0070]

[0071] Wherein, the hot melt adhesive prepared in Example 1 is as follows Figure 1 As shown, the hot melt adhesive prepared in Comparative Example 1 is as follows Figure 2 As shown, the hot melt adhesive prepared in Comparative Example 2 is as follows Figure 3 shown.

[0072] according to Figure 1-3 As can be seen from the results in Table 2:

[0073] 1. Examples 1-3 are methods for preparing hot melt adhesives provided by the present invention. Comparative Example 1 does not use polycarbonate polyether polyol and polyether polyol, and Comparative Example 2 does not use polycarbonate polyether polyol and latent curing agent. Except for the different amounts of polyester polyol, polycarbonate polyether polyol, polyether polyol and latent curing agent used in the above examples and comparative examples, the other components and amounts are the same. The colloid in Comparative Example 1 has an overall grayish white color and is translucent (such as Figure 2 As shown in the figure, it can be seen that the compatibility is poor; Comparative Example 2 uses polyether polyol, and its colloid is white as a whole, opaque, and its white concentration is significantly higher than that of Comparative Example 2, and the compatibility is extremely poor. The hot melt adhesives prepared in Examples 1-3 provided by the present invention can all present a transparent light yellow appearance, such as Figure 1As shown, the hot melt adhesive prepared in Example 1 is transparent, the bottom of the cup can almost be seen, and the compatibility is good. It can not only solve the miscibility problem of polyether polyols, but also solve the compatibility problem of latent curing agents composed of polyether polyamines as the main body. Compared with Comparative Examples 1 and 2, it has very significant effects.

[0074] 2. In addition, when only the dosage of polyester polyol, polycarbonate polyether polyol, polyether polyol and latent curing agent is adjusted, the final bonding shear strength of Example 2 reaches 5.8, and the final bonding shear strength of Example 3 can reach 7.4. It can be seen that the present invention increases the final bonding strength of the hot melt adhesive to varying degrees, with significant effects.

[0075] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the method disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0076] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol, which is made of the following raw materials in the following weight ratios: 65-95 weight parts of polyurethane prepolymer, 5-30 weight parts of modifier and 0.2-5 weight parts of auxiliary agent; The polyurethane prepolymer is obtained by reacting a polyol with an excess of isocyanate; The modifier is selected from at least one of vinyl acetate polymers, copolymers of vinyl acetate and ethylene, acrylic polymers and copolymers thereof, and thermoplastic polyurethane polymers; The auxiliary agent is selected from at least one of a catalyst, a leveling agent, an antioxidant, a latent curing agent, an ultraviolet absorber and a deodorant; The polyol is selected from a combination of polyester polyol and polycarbonate polyether polyol, a combination of polyether polyol and polycarbonate polyether polyol, or a combination of polyester polyol, polyether polyol and polycarbonate polyether polyol, and the proportion of the polycarbonate polyether polyol in the total mass of the polyol is not less than 3%.

2. The moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol according to claim 1, characterized in that: The isocyanate is selected from any one of MDI, TDI, NDI, IPDI and HDI; The reaction R value of the polyol and isocyanate is between 1.4-5.0%; The R value is the ratio of the molar number of isocyanate to the molar number of hydroxyl, that is, R=NCO / OH.

3. The moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol according to claim 2, characterized in that: The structural formula of the polycarbonate polyether polyol is shown in Formula I: H-(-O-R1-O-CO-)m-(-O-R2-)n-OH Formula I In the formula I, R1 and R2 are both selected from any one of C1-C5 alkyl groups; m is the polycarbonate unit contained in each molecule; m≥1; n is the number of polyether units contained in each molecule; n≥1.

4. The moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol according to claim 2, characterized in that: R1 and R2 are both selected from any one of C1-C4 alkyl groups.

5. The moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol according to claim 2, characterized in that: R1 and R2 are both selected from any one of methylene, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl and isopentyl.

6. The moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol according to claim 1, characterized in that: The polyurethane prepolymer is obtained by reacting a polyol with an excess of isocyanate: after removing water from the polyol and cooling it, isocyanate is added and stirred to obtain the polyurethane prepolymer.

7. The moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol according to claim 6, characterized in that: After adding isocyanate and stirring, defoaming treatment is also included.

8. The moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol according to claim 6, characterized in that: The polyol dehydration and cooling is to heat the polyol to 100-130°C and remove water in vacuum, the vacuum degree is -0.09MPa to -0.1MPa, and the vacuum holding time is more than 0.5h; The cooling temperature is 40-100°C; The stirring time is at least 30 minutes, and the stirring rate is 100-500 r / min.

9. The moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol according to claim 1, characterized in that: The modifier is selected from at least one of vinyl acetate polymer, acrylic polymer and thermoplastic polyurethane polymer.

10. A method for preparing the moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol according to any one of claims 1 to 9, which is obtained by adding a modifier and an auxiliary agent when preparing a polyurethane prepolymer, specifically comprising: S1. Add polyol into the container according to the raw material metering ratio, start heating, start stirring after the material temperature reaches 100-130°C, the stirring speed is 200r / min, the vacuum is more than 0.5h, the vacuum degree is between -0.09MPa and -0.1MPa, and the vacuum is stopped after the water content is detected to be less than 500ppm; S2. Stop stirring, release the vacuum, cool to 80°C, add isocyanate, stir at 500r / min for 40min, and then test NCO%; then test NCO% every 30-60min until NCO% reaches the designed theoretical value ±0.2%; S3. Add modifier and / or auxiliary agent according to the raw material metering ratio, and stir under vacuum for at least 30 minutes at a stirring speed of 100r / min and a vacuum degree between -0.09MPa and -0.1MPa. After the materials are mixed evenly without bubbles, they can be discharged, filled with nitrogen, and sealed for storage.

11. The method according to claim 10, characterized in that: Step S1: When adding polyol into the container according to the raw material metering ratio, add a modifier and / or an auxiliary agent.

12. Use of the moisture-curable polyurethane hot melt adhesive containing polycarbonate polyether polyol according to any one of claims 1 to 9 in bonding.

13. A bonding product comprising the moisture-curing polyurethane hot melt adhesive containing polycarbonate polyether polyol according to any one of claims 1 to 9.

Images