High foaming rate hot melt adhesive and preparation and use thereof

Abstract

The present application relates to the field of hot melt adhesive, and provides a high-foaming hot melt adhesive as well as preparation and application thereof.The hot melt adhesive comprises polyolefin elastomer and functional polymer in a mass ratio of 40-90:1-10;the functional polymer is a copolymer of a first monomer and a second monomer;the first monomer is selected from one or more than two combinations of ethylene monomer, propylene monomer, butene monomer, hexene monomer and octene monomer;the second monomer is selected from one or more than two combinations of maleic anhydride, acrylic acid and acrylic acid derivative;and the content of the second monomer in the functional polymer is 1-30%.By adding the functional polymer with specific structure and content, the cohesive strength of the material is improved, the air bubbles in the foaming process can be supported, so that the foaming rate is improved, and the cohesive strength of the material is also improved.Meanwhile, the functional groups of the functional polymer can also increase the adhesion of the hot melt adhesive material to metal.

Description

Technical Field

[0001] This invention relates to the field of hot melt adhesive technology, and in particular to a high foaming rate hot melt adhesive and its preparation and application. Background Technology

[0002] Currently, three types of materials are mainly used for sealing the corner seams of air conditioner evaporators: silicone-based sealing damping strips, EVA-based hot melt adhesives, and polyolefin elastomer hot melt adhesives.

[0003] Silicone-based sealing damping strips suffer from drawbacks such as poor sealing performance, inconvenient operation, and low efficiency. EVA-based hot melt adhesives, made from ethylene-vinyl acetate copolymer, have poor thermal stability and decompose to release low-molecular-weight acidic substances, while also requiring large amounts of adhesive. Both of these types of hot melt adhesives are gradually being replaced by polyolefin elastomer hot melt adhesives in the market. Currently, polyolefin elastomer hot melt adhesives also have certain problems. Because polyolefin elastomer materials are relatively expensive, foaming and application are used to reduce costs. However, the foaming degree of currently used polyolefin elastomer hot melt adhesives is relatively low, generally around 40-50%. Summary of the Invention

[0004] As mentioned above, the sealant used for sealing the corner seams of air conditioner evaporators must meet the requirements of good sealing performance, good thermal stability, and low cost. Although foaming and applying polyolefin elastomer hot melt adhesive can solve some of the above problems, such as effectively avoiding the disadvantages of poor sealing performance, inconvenient operation, and low efficiency of silicone-based sealing damping strips, and the disadvantages of EVA-based hot melt adhesives such as large adhesive consumption and the precipitation of acidic substances that corrode evaporator components, the foaming process of polyolefin elastomer hot melt adhesive makes it a technical challenge that urgently needs to be overcome in this field.

[0005] This invention provides a high foaming rate hot melt adhesive, its preparation, and its application. By introducing specific types of functional polymers into the existing polyolefin elastomer hot melt adhesive system, an improved hot melt adhesive is obtained, achieving the preparation of a high foaming rate polyolefin elastomer hot melt adhesive. At the same time, this high foaming rate polyolefin elastomer hot melt adhesive also exhibits the technical characteristic of high adhesion, improving the sealing performance of the hot melt adhesive. It has a greater technical advantage in applications with high requirements for foaming and sealing performance, such as sealing materials for air conditioner evaporators.

[0006] Specifically, in a first aspect, the present invention provides a high foaming rate hot melt adhesive, comprising: a polyolefin elastomer and a functional polymer in a mass ratio of 40~90:1~10;

[0007] The functional polymer is a copolymer of a first monomer and a second monomer; the content of the second monomer in the functional polymer is 1-30%.

[0008] The first monomer is selected from one or more of ethylene monomers, propylene monomers, butene monomers, hexene monomers, and octene monomers;

[0009] The second monomer is selected from one or more of maleic anhydride, acrylic acid, and acrylic acid derivatives.

[0010] According to the high foaming rate hot melt adhesive provided by the present invention, the acrylic derivative is selected from one or more combinations of methyl methacrylate, ethyl methacrylate, butyl methacrylate and glycidyl methacrylate.

[0011] The high foaming rate hot melt adhesive provided by the present invention further includes: a tackifying resin; the mass ratio of the polyolefin elastomer to the tackifying resin is 40~90:5~40;

[0012] Preferably, the tackifying resin is selected from one or more of rosin resin, petroleum resin and terpene resin.

[0013] According to the high foaming rate hot melt adhesive provided by the present invention, the petroleum resin is selected from one or more of C5 petroleum resin, hydrogenated C5 petroleum resin, C9 petroleum resin and hydrogenated C9 petroleum resin.

[0014] The high foaming rate hot melt adhesive provided by the present invention further includes polyisobutylene; the mass ratio of the polyolefin elastomer to the polyisobutylene is 40~90:1~20.

[0015] The high foaming rate hot melt adhesive provided by the present invention further includes a heat-oxygen stabilizer; the mass ratio of the polyolefin elastomer to the heat-oxygen stabilizer is 40~90:0.1~1;

[0016] Preferably, the thermo-oxidative stabilizer is a hindered phenolic antioxidant and / or a phosphite antioxidant.

[0017] According to the high foaming rate hot melt adhesive provided by the present invention, the basic monomer constituting the polyolefin elastomer is ethylene.

[0018] According to the high foaming rate hot melt adhesive provided by the present invention, the raw materials of the high foaming rate hot melt adhesive, by weight, include: 40-90 parts of polyolefin elastomer, 1-20 parts of polyisobutylene, 5-40 parts of tackifying resin, 1-10 parts of functional polymer, and 0.1-1 parts of heat and oxygen stabilizer. Experiments have shown that the hot melt adhesive prepared using this formulation has better performance.

[0019] Secondly, the present invention also provides a method for preparing the high foaming rate hot melt adhesive as described above, wherein the raw materials are melted and mixed and then molded to obtain the high foaming rate hot melt adhesive.

[0020] According to the preparation method of the high foaming rate hot melt adhesive provided by the present invention, the melting and mixing temperature is 140~200℃.

[0021] Thirdly, the present invention also provides the application of the high foaming rate hot melt adhesive as described above or the high foaming rate hot melt adhesive prepared by the preparation method as described above in corner seam sealing.

[0022] Fourthly, the present invention also provides a sheet metal part with a corner joint, wherein the corner joint is sealed using a high-foaming-rate hot melt adhesive as described above or a high-foaming-rate hot melt adhesive prepared by the preparation method described above.

[0023] The high-expansion hot melt adhesive, its preparation, and its application provided by this invention improve the cohesive strength of the material by adding functional polymers with specific structures and contents. This allows the hollow cells to be supported during the foaming process, thereby increasing the foaming rate and improving the cohesive strength of the material. Simultaneously, the functional groups on the functional polymers also increase the adhesion of the hot melt adhesive material to metals. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] In an embodiment of the present invention, a high foaming rate hot melt adhesive is first provided, comprising: a polyolefin elastomer and a functional polymer in a mass ratio of 40~90:1~10;

[0026] The functional polymer is a copolymer of a first monomer and a second monomer; the content of the second monomer in the functional polymer is 1-30%.

[0027] The first monomer is selected from one or more of ethylene monomers, propylene monomers, butene monomers, hexene monomers, and octene monomers;

[0028] The second monomer is selected from one or more of maleic anhydride, acrylic acid, and acrylic acid derivatives.

[0029] In this invention, the first monomer constituting the functional polymer is the basic monomer of the functional polymer, exhibiting good compatibility with polyolefin elastomers. The second monomer, in addition to containing groups that copolymerize with the first monomer, also contains other reactive groups, such as carbonyl or epoxy groups, which endow the functional polymer with a certain degree of reactivity. When this functional polymer is added to a hot melt adhesive, firstly, the functional polymer can increase the intermolecular forces of the polymer chains constituting the hot melt adhesive, thereby increasing the cohesive strength of the hot melt adhesive. This cohesive strength can support the hollow cell structure when the hot melt adhesive is applied, achieving a higher foaming ratio, and the foamed structure exhibits good stability and high strength. Secondly, when the hot melt adhesive is applied, the functional polymer can also react with the materials it contacts, thereby increasing the adhesion of the hot melt adhesive to materials such as metals.

[0030] In the aforementioned functional polymers, the content of the second monomer should be appropriate. To ensure the effectiveness of the two aspects mentioned above, the content of the second monomer should be above 1%. If the content of the second monomer is too high, the hot melt adhesive will lose its fluidity and cannot be processed. Therefore, the content of the second monomer in the functional polymer should be controlled within 30%.

[0031] In a specific embodiment of the present invention, the content of the second monomer in the functional polymer is 1-30%, for example, it can be any value or a range of any values ​​among 1%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25%, 27%, 29% and 30%.

[0032] Preferably, the molecular weight of the functional polymer of the present invention is Mn=10000~200000.

[0033] Preferably, when the functional polymer uses a mixture of two or more monomers as the second monomer, it is more beneficial to improve the cohesive strength of the hot melt adhesive of the present invention; more preferably, the second monomer is a mixture of maleic anhydride and acrylic acid derivative, and more preferably, the mass ratio of maleic anhydride and acrylic acid derivative is 1:5 to 1:1.

[0034] Experiments have shown that the closer the molecular chain structure of the first monomer used in the functional polymer is to that of the basic monomer used in the polyolefin elastomer, the better the compatibility between the components and the more conducive it is to forming intermolecular forces between the components. Therefore, it is preferable that the first monomer is the same as the monomer constituting the polyolefin elastomer; more preferably, the first monomer is the same as the basic monomer constituting the polyolefin elastomer.

[0035] In a specific embodiment of the present invention, the acrylic derivative is selected from one or more combinations of methyl methacrylate, ethyl methacrylate, butyl methacrylate and glycidyl methacrylate.

[0036] In a specific embodiment of the present invention, it further includes: a tackifying resin; the mass ratio of the polyolefin elastomer to the tackifying resin is 40~90:5~40; preferably 50~80:10~30; more preferably 60~70:15~20.

[0037] In the hot melt adhesive of this invention, the role of the tackifying resin includes adjusting the adhesion of the hot melt adhesive to the substrate and adjusting the stability of the cell structure formed during the foaming process. Cell stability is closely related to the crystallization and shrinkage properties of the hot melt adhesive. Experiments have shown that if the content of the tackifying resin is too high, the viscosity of the formulation system will be too low and the fluidity will be too good, making it difficult to apply and causing it to flow between the metal fins of the evaporator; at the same time, the cohesive strength of the hot melt adhesive system will decrease, and the foaming will be unstable. If the content of the tackifying resin is too low, the viscosity of the formulation system will be too high, the wetting performance will be poor, and the surface will not adhere well to the evaporator, resulting in low adhesion.

[0038] Preferably, the tackifying resin is selected from one or more of rosin resin, petroleum resin and terpene resin.

[0039] Compared to other substances, the tackifying resin selected in this invention is more suitable for this invention in terms of better compatibility with the matrix resin polyolefin elastomer and better wettability with the metal surface of the evaporator.

[0040] In a specific embodiment of the present invention, the petroleum resin is selected from one or more of C5 petroleum resin, hydrogenated C5 petroleum resin, C9 petroleum resin and hydrogenated C9 petroleum resin.

[0041] In a specific embodiment of the present invention, polyisobutylene is also included; the mass ratio of the polyolefin elastomer to the polyisobutylene is 40~90:1~20.

[0042] Preferably, the kinematic viscosity (100°C) of the polyisobutylene is 300~3000 mmHg. 2 / s.

[0043] In a specific embodiment of the present invention, a heat-oxygen stabilizer is also included; the mass ratio of the polyolefin elastomer to the heat-oxygen stabilizer is 40~90:0.1~1;

[0044] Preferably, the thermo-oxidative stabilizer is a hindered phenolic antioxidant and / or a phosphite antioxidant.

[0045] In a specific embodiment of the present invention, the basic monomer constituting the polyolefin elastomer is ethylene.

[0046] Preferably, the other monomers constituting the polyolefin elastomer are one or more of propylene, butene, hexene and octene.

[0047] The polyolefin elastomer includes atactic and / or atactic polyolefins.

[0048] In embodiments of the present invention, when the other monomers constituting the polyolefin elastomer are propylene monomers, the material itself has higher cohesive strength and better foaming performance.

[0049] In a specific embodiment of the present invention, the raw materials of the high foaming rate hot melt adhesive, by weight, include: 40-90 parts of polyolefin elastomer, 1-20 parts of polyisobutylene, 5-40 parts of tackifying resin, 1-10 parts of functional polymer, and 0.1-1 parts of thermo-oxidative stabilizer.

[0050] In a specific embodiment of the present invention, the polyolefin elastomer is 40 to 90 parts, for example, it can be any value or a range of any values ​​among 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts and 90 parts.

[0051] In a specific embodiment of the present invention, the polyisobutylene is 1 to 20 parts, for example, any value or range of any value among 1 part, 3 parts, 5 parts, 7 parts, 9 parts, 11 parts, 13 parts, 15 parts, 17 parts, 19 parts and 20 parts.

[0052] In a specific embodiment of the present invention, the tackifying resin is 5 to 40 parts, for example, any value or range of any value among 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts and 40 parts.

[0053] In a specific embodiment of the present invention, the functional polymer is 1 to 10 parts, for example, any value or range of any value among 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts and 10 parts.

[0054] In a specific embodiment of the present invention, the thermo-oxidative stabilizer is 0.1 to 1 part, for example, it can be any value or a range of any values ​​among 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts and 1.0 parts.

[0055] In embodiments of the present invention, a method for preparing the high foaming rate hot melt adhesive as described above is also provided, wherein the raw materials are melted and mixed and then molded to obtain the high foaming rate hot melt adhesive.

[0056] In a specific embodiment of the present invention, the melting and mixing temperature is 140~200℃.

[0057] In a specific embodiment of the present invention, the preparation method includes the following steps:

[0058] The tackifying resin, polyisobutylene, and thermo-oxidative stabilizer are melt-mixed at a temperature of 140~200℃ for 20~60min to obtain the first mixture;

[0059] The functional polymer, polyolefin elastomer and the first mixture are melt-mixed at a temperature of 140~200℃ for 50~80min to obtain the second mixture;

[0060] After the temperature of the second mixture is reduced to 140~160℃, it is evacuated until there are no bubbles, and then it is molded.

[0061] The molding process of this invention can be carried out using molding equipment such as underwater pelletizers and steel strip pelletizers. After molding, cooling, drying, and packaging steps can be optionally performed.

[0062] In the processing of the hot melt adhesive of this invention, the order of adding each raw material needs to be controlled. Specifically, the tackifying resin, polyisobutylene, and thermo-oxidative stabilizer are mixed first, primarily to premix the non-matrix resin and additives. Then, the functional polymer and polyolefin elastomer are mixed with the aforementioned materials, which allows for better dispersion and mixing of the matrix resin, non-matrix resin, and additives. Furthermore, controlling the temperature within the range of 140~200°C during the mixing process helps all materials melt, while maintaining a suitable viscosity for the dispersion and mixing of the non-matrix resin and additives.

[0063] In embodiments of the present invention, the application of the high foaming rate hot melt adhesive as described above or the high foaming rate hot melt adhesive prepared by the method described above in corner seam sealing is also provided.

[0064] In a specific embodiment of the present invention, the application includes: sealing the corner seams of an air conditioner evaporator.

[0065] In an embodiment of the present invention, a sheet metal part with a corner seam is also provided, wherein the corner seam is sealed using a high foaming rate hot melt adhesive as described above and a high foaming rate hot melt adhesive prepared by the preparation method described above.

[0066] The preferred embodiments of the present invention will be described in detail below. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased from legitimate channels.

[0067] The APAO grades used in this invention include, but are not limited to, one or more combinations selected from examples such as 308, 408, 508, 520, 608, EPV2103, EP V2094, 703, 704, 708, 750, 751, 792, 828 and 888, RT2115, RT 2180, RT2215, RT3460, and RT2732. All currently commercially available APAO resin grades can also achieve the objectives of this invention.

[0068] Example 1

[0069] A high foaming rate hot melt adhesive, the raw material composition by weight is shown in the table below:

[0070]

[0071] A method for preparing a high foaming rate hot melt adhesive, comprising preparing materials according to the above-mentioned raw material composition, and the specific preparation steps are as follows:

[0072] (1) Heat the reactor to 180°C.

[0073] (2) The above-mentioned tackifying resin, polyisobutylene and thermo-oxidative stabilizer are added to the reactor heated in step (1) in sequence, the temperature is kept at 180°C, and the mixture is stirred for 40 minutes until all raw materials are completely melted and mixed.

[0074] (3) Add the above functional polymer and polyolefin elastomer into the reactor of step (2), keep the temperature at 180°C, stir for 70 minutes, and all materials are completely melted and mixed evenly.

[0075] (4) Reduce the temperature of the material after mixing in step (3) to 140°C, seal the reactor, and stir the reactor until there are no bubbles.

[0076] (5) Put the material obtained in step (4) into the storage tank, open the valve, and discharge the material to the underwater pelletizer to form a high foaming rate hot melt adhesive.

[0077] Example 2

[0078] A high foaming rate hot melt adhesive, the raw material composition by weight is shown in the table below:

[0079]

[0080] A method for preparing a high foaming rate hot melt adhesive, comprising preparing materials according to the above-mentioned raw material composition, and the specific preparation steps are as follows:

[0081] (1) Heat the reactor to 170°C.

[0082] (2) The above-mentioned tackifying resin, polyisobutylene and thermo-oxidative stabilizer are added to the reactor heated in step (1) in sequence, the temperature is kept at 170°C, and the mixture is stirred for 60 minutes until all raw materials are completely melted and mixed.

[0083] (3) Add the above functional polymer and polyolefin elastomer into the reactor of step (2), keep the temperature at 170°C, stir for 60 minutes, and all materials are completely melted and mixed evenly.

[0084] (4) Reduce the temperature of the material after mixing in step (3) to 140°C, seal the reactor, and stir the reactor until there are no bubbles.

[0085] (5) Put the material obtained in step (4) into the storage tank, open the valve, and discharge the material to the underwater pelletizer to form a high foaming rate hot melt adhesive.

[0086] Example 3

[0087] A high foaming rate hot melt adhesive, the raw material composition by weight is shown in the table below:

[0088]

[0089] A method for preparing a high foaming rate hot melt adhesive, comprising preparing materials according to the above-mentioned raw material composition, and the specific preparation steps are as follows:

[0090] (1) Heat the reactor to 180°C.

[0091] (2) The above-mentioned tackifying resin, polyisobutylene and thermo-oxidative stabilizer are added to the reactor heated in step (1) in sequence, the temperature is kept at 180°C, and the mixture is stirred for 40 minutes until all raw materials are completely melted and mixed.

[0092] (3) Add the above functional polymer and polyolefin elastomer into the reactor of step (2), keep the temperature at 180°C, stir for 70 minutes, and all materials are completely melted and mixed evenly.

[0093] (4) Reduce the temperature of the material after mixing in step (3) to 140°C, seal the reactor, and stir the reactor until there are no bubbles.

[0094] (5) Put the material obtained in step (4) into the storage tank, open the valve, and discharge the material to the underwater pelletizer to form a high foaming rate hot melt adhesive.

[0095] Example 4

[0096] It is basically the same as Example 1, except that the functional polymer is replaced by an equal mass of a copolymer of acrylic acid and ethylene, brand name NUCREL 30907.

[0097] Example 5

[0098] It is basically the same as Example 1, except that hydrogenated C5 petroleum resin is replaced by terpene resin.

[0099] Comparative Example 1

[0100] It is basically the same as Example 1, except that the functional polymer is replaced by the polyolefin elastomer in Example 1 by the same mass, that is, no functional polymer is added.

[0101] Comparative Example 2

[0102] It is basically the same as Example 1, except that the functional polymer is replaced by an ionomer, Salin resin 1601.

[0103] Comparative Example 3

[0104] It is basically the same as Example 1, except that the functional polymer is replaced by polyethylene graft (grafted monomer MAH), grade CMG5805.

[0105] Test case

[0106] In this invention, the foaming rate is tested as follows: Using a disposable paper cup, the weight of the paper cup is removed from the tare (by removing the paper cup's weight). A full cup of glue (unfoamed) is then added, with a weight capacity of V. The foaming process is then adjusted, and a full cup of foamed glue is added, with a weight of W (again, the paper cup's weight is removed). Therefore, the foaming rate = (1 - W / v) × 100%.

[0107] Other performance indicators shall be implemented in accordance with the national standards commonly used in this field.

[0108] The test results of the above embodiments and comparative examples are as follows:

[0109]

[0110] As can be seen from the above results, the hot melt adhesive containing a functional polymer with a specific structure provided by the present invention has a high foaming rate, tensile strength and metal peeling force. Compared with other commonly used polymers as additives, it is more suitable for use in corner seam sealing.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high foaming rate hot melt adhesive, characterized in that, By weight, the raw materials of the high foaming rate hot melt adhesive consist of 40-90 parts of polyolefin elastomer, 1-20 parts of polyisobutylene, 5-40 parts of tackifying resin, and 1-10 parts of functional polymer. The tackifying resin is selected from one or more of rosin resin, petroleum resin and terpene resin; The polyisobutylene has a kinematic viscosity of 300~3000 mm at 100°C. 2 / s; The functional polymer is a copolymer of a first monomer and a second monomer; the content of the second monomer in the functional polymer is 1-30%. The first monomer is selected from one or more of ethylene monomers, propylene monomers, butene monomers, hexene monomers, and octene monomers; The second monomer is a mixture of maleic anhydride and an acrylic acid derivative; the mass ratio of maleic anhydride to acrylic acid derivative is 1:5 to 1:1; the acrylic acid derivative is selected from one or more of methyl methacrylate, ethyl methacrylate, butyl methacrylate and glycidyl methacrylate.

2. The high foaming rate hot melt adhesive according to claim 1, characterized in that, The petroleum resin is selected from one or more of C5 petroleum resin, hydrogenated C5 petroleum resin, C9 petroleum resin and hydrogenated C9 petroleum resin.

3. The high foaming rate hot melt adhesive according to claim 1, characterized in that, It also includes a heat-oxygen stabilizer; the mass ratio of the polyolefin elastomer to the heat-oxygen stabilizer is 40~90:0.1~1; The thermo-oxidative stabilizer is a hindered phenolic antioxidant and / or a phosphite antioxidant.

4. The high foaming rate hot melt adhesive according to any one of claims 1 to 3, characterized in that, The basic monomer constituting the polyolefin elastomer is ethylene.

5. A method for preparing the high foaming rate hot melt adhesive according to any one of claims 1 to 4, characterized in that, The high foaming rate hot melt adhesive is obtained by melting and mixing the raw materials and then molding them; the melting and mixing temperature is 140~200℃.

6. The application of the high foaming rate hot melt adhesive according to any one of claims 1 to 4 or the high foaming rate hot melt adhesive prepared by the preparation method according to claim 5 in corner seam sealing.

7. A sheet metal component with a corner seam, characterized in that, The corner seam seal uses a high-foaming-rate hot melt adhesive as described in any one of claims 1 to 4 or a high-foaming-rate hot melt adhesive prepared by the preparation method described in claim 5.

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