An oxacycle-capped resin and an adhesive using the same

Abstract

The present invention provides an oxacycle-capped resin and an adhesive using the same. The preparation method of the oxacycle-capped resin comprises the following steps: S1. A polymerization reaction is carried out between a low molecular weight diol and a diisocyanate at 70-75 °C until the low molecular weight diol reacts completely, thereby obtaining an isocyanate-capped prepolymer. Among them, the molecular weight of the low molecular weight diol is 500-3000, and the feeding ratio of the low molecular weight diol and the diisocyanate is determined according to the molar ratio of the isocyanate groups of the diisocyanate to the hydroxyl groups of the low molecular weight diol being 1.02-1.1; S2. Subsequently, oxetane alcohol ester is added to the prepolymer, and the reaction is carried out at 80-85 °C for 1-4 h to obtain the oxacycle-capped resin. Among them, the feeding ratio of the prepolymer and the oxetane alcohol ester is determined according to the molar ratio of the hydroxyl groups of the oxetane alcohol ester to the isocyanate groups of the prepolymer being 1.02-1.1.

Description

Technical Field

[0001] The present invention belongs to the field of thermosetting materials, and particularly relates to an oxacycle-capped resin and an adhesive using the same. Background Art

[0002] Currently, the commonly used adhesives include one-component adhesives and two-component adhesives. Among them, one-component adhesives refer to the mixing and piping of main agents, curing agents and other additives, and no glue mixing is required during use; while two-component adhesives need to separately package and pipe the main agent and curing agents and other additives, and need to be mixed in a special ratio before use. Generally, the curing speed of one-component adhesives on the market is slower than that of two-component adhesives. However, the convenience of one-component adhesives in the processing technology cannot be ignored.

[0003] Epoxy resins have excellent properties and are often used as the base materials of adhesives. However, due to the existence of a large number of benzene ring structures, epoxy resins have defects such as poor flexibility and high modulus after curing, and are prone to cracking during use due to mechanical stress or temperature changes, resulting in limited applications of epoxy adhesives.

[0004] In recent years, higher and higher requirements have been put forward for the performance of epoxy adhesives in practical applications. For example, in addition to meeting the necessary mechanical strength, epoxy adhesives also need to have good toughness and simple processability. In the prior art, rubber particle toughened modified epoxy resins are used for chemical toughening. However, such modified epoxy resins have a high viscosity and a limited addition ratio, so the improvement of the flexible performance of epoxy adhesives is also limited. In addition, the flexible performance of epoxy adhesives is improved by adding polyols. However, this method will reduce the heat resistance of the adhesives. Therefore, in the existing epoxy resin adhesive technology, adding a toughening agent to the epoxy resin adhesive to improve the flexibility of the epoxy resin adhesive will reduce the processing performance and heat resistance of the epoxy resin adhesive. Summary of the Invention

[0005] In order to improve the problems such as high modulus, poor flexibility after curing of epoxy resin adhesives, and the reduction of the processing performance and heat resistance of epoxy resin adhesives after adding a toughening agent, the present invention provides an oxacycle-capped resin and an adhesive using the same.

[0006] According to one aspect of the present invention, an oxacyclic-capped resin is provided. The preparation method of the oxacyclic-capped resin comprises the following steps: S1. A polymerization reaction is carried out between an oligomeric diol and a diisocyanate at 70 - 75 °C until the oligomeric diol reacts completely, thereby obtaining an isocyanate-capped prepolymer. Herein, the molecular weight of the oligomeric diol is 500 - 3000, and the feeding ratio of the oligomeric diol and the diisocyanate is determined according to the molar ratio of the isocyanate functional groups of the diisocyanate to the hydroxyl functional groups of the oligomeric diol being 1.02 - 1.1; S2. Subsequently, oxetane alcohol is added to the prepolymer, and a reaction is carried out at 80 - 85 °C for 1 - 4 h to obtain the oxacyclic-capped resin. Herein, the feeding ratio of the prepolymer and the oxetane alcohol is determined according to the molar ratio of the hydroxyl functional groups of the oxetane alcohol to the isocyanate functional groups of the prepolymer being 1.02 - 1.1.

[0007] Compared with the rubber particle toughened modified epoxy resin or rigid epoxy resin in the prior art, the oxacyclic-capped resin obtained by using the preparation method provided by the present invention has a lower viscosity. Therefore, the content of the oxacyclic-capped resin in the epoxy resin adhesive can be increased, and good flexibility and a lower modulus can be provided for the epoxy resin adhesive, and the simple processing performance and heat resistance of the epoxy resin adhesive will not be reduced. The structural formula of the oxacyclic-capped resin is as follows:

[0008]

[0009] wherein, R 1 is the part in the molecular structure of the oligomeric diol that does not contain hydroxyl functional groups, and R 2 is the part in the molecular structure of the diisocyanate that does not contain isocyanate functional groups.

[0010] Preferably, in S1, the oligomeric diol needs to be pre-dehydrated in a vacuum drying oven at 105 - 120 °C first, and then the dehydrated oligomeric diol is mixed with a catalyst under an inert gas atmosphere, and then the diisocyanate is added, and a polymerization reaction is carried out at 70 - 75 °C until the oligomeric diol reacts completely, thereby obtaining the isocyanate-capped prepolymer.

[0011] Preferably, the catalyst includes at least one of dibutyltin dilaurate (DBTDL), bis(dimethylaminoethyl) ether, pentamethyldiethylenetriamine, dimethylcyclohexylamine, organobismuth, and organozinc.

[0012] Preferably, the oligomeric diol includes at least one of polyester diol, polyether diol, polyolefin diol, vegetable oil diol, and epoxy resin diol.

[0013] Preferably, the polyester diol includes at least one of an aliphatic polyester diol, an adipic acid-based polyester diol, an unsaturated aliphatic polyester diol, a caprolactone-based polyester diol, and an aromatic polyester diol.

[0014] Preferably, the polyether diol includes at least one of polytetrahydrofuran diol, polypropylene glycol, and polyethylene glycol.

[0015] Preferably, the polyolefin diol includes at least one of polyethylene diol, polybutene diol, polyisoprene diol, polyethylene-butene diol, polystyrene-polyethylene diol, hydroxyl-terminated polybutadiene, hydroxyl-terminated polybutadiene-acrylonitrile, hydroxyl-terminated polyisoprene, hydroxyl-terminated ethylene-ethylene, and hydroxyl-terminated hydrogenated polyisoprene.

[0016] Preferably, the vegetable oil diol includes a diol prepared or modified with castor oil, palm oil, linseed oil, soybean oil, sunflower oil, or corn oil.

[0017] Preferably, the epoxy resin diol includes polypropylene oxide diol.

[0018] Preferably, the oligomer diol has a functionality of 2 to 3 and a hydroxyl value of 200 to 500 mgKOH / g. Herein, the functionality is the average number of specific functional group types located on the molecule. For example, an oligomer diol with a functionality of 2 means a molecule that contains two hydroxyl groups on average per molecule.

[0019] Preferably, the diisocyanate includes at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate.

[0020] Preferably, the oxetane alcohol includes at least one of 3-oxetanol, 3-ethyl-3-oxetanemethanol, 3-ethynyloxetan-3-ol, [3-(propan-2-yl)oxetan-3-yl]methanol, and 3-isopropyloxetan-3-ol.

[0021] In the second aspect of the present invention, an adhesive is provided. The raw materials for preparing the adhesive include any one of the above-mentioned oxacycle-capped resins. Among them, calculated by mass parts, the raw materials for preparing the adhesive include 50-100 parts of epoxy resin, 10-100 parts of oxetane monomer, 20-100 parts of oxacycle-capped resin, and 0.1-2 parts of heat-initiated cationic curing agent. For the adhesive provided by the present invention, the oxacycle-capped resin as a toughening agent can significantly reduce the modulus of the adhesive, enhance the toughness of the adhesive, improve the phenomenon that the epoxy resin adhesive is prone to cracking after curing, and will not reduce the processing performance and heat resistance of the adhesive. Moreover, the epoxy resin and oxetane monomer combined with the adhesive can synergistically enhance the bonding performance, heat resistance and anti-aging performance of the adhesive. In addition, by adjusting the ratio among the epoxy resin, oxetane monomer and oxacycle-capped resin, the viscosity of the adhesive can be adjusted, thereby reducing the modulus of the adhesive and enhancing the flexibility of the adhesive. And by combining with the heat-initiated cationic curing agent, the curing speed of the adhesive can be effectively increased. Thus, the adhesive provided by the present invention can have good bonding performance, heat resistance, flexibility, processing performance, as well as low viscosity and fast curing speed.

[0022] Preferably, the epoxy resin includes alicyclic epoxy resin, among which the alicyclic epoxy resin includes at least one of 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate, poly[(2-epoxyethyl)-1,2-cyclohexanediol] 2-ethyl-2-(hydroxymethyl)-1,3-propanediol ether, bis((3,4-epoxycyclohexyl)methyl) adipate, tetrahydroindene dioxide, 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexylmethyl methacrylate, 3,4-epoxycyclohexyl methacrylate, divinylcyclohexene dioxide.

[0023] Preferably, the oxetane monomer includes at least one of 3-ethyl-3-hydroxymethyloxetane (OXT-101), 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane (OXT-212), 3,3'-(oxybis(methylene))bis(3-ethyl)oxetane (OXT-221), 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene (OXT-121).

[0024] Preferably, the heat-initiated cationic curing agent includes at least one of aryl diazonium salt curing agents, aryl iodonium salt curing agents, aryl sulfonium salt curing agents, and allene-ion complex curing agents.

[0025] Preferably, the aryl iodonium salt curing agent includes at least one of diaryl iodonium salts and triaryl iodonium salts.

[0026] Preferably, the arylsulfonium salt curing agent includes at least one of triarylsulfonium hexafluoroantimonate, 4-hydroxyphenyl-methyl(2-methylbenzyl)sulfonium hexafluoroantimonate, and benzyl(4-hydroxyphenyl)-methylsulfonium hexafluoroantimonate.

[0027] Preferably, the allene-ion complex curing agent includes dimethyldiallylammonium chloride.

[0028] Preferably, the adhesive further includes a filler, and the filler includes at least one of silica powder, talc powder, calcium carbonate, and mica powder.

[0029] Preferably, the adhesive further includes an additive, and the additive includes at least one of a coupling agent, an antifoaming agent, and a leveling agent.

[0030] Preferably, the antifoaming agent includes at least one of BYK A535 and BYK066N.

[0031] Preferably, the coupling agent includes at least one of KH560, KH570, and KH792.

[0032] Preferably, the leveling agent includes at least one of BYK-397 and BYK354.

[0033] In the third aspect of the present invention, there is provided an adhesive layer, which is a cured product of any one of the above adhesives. The adhesive layer can have good bonding properties to metals, films, fibers, etc., and can provide good heat resistance, anti-aging properties, and anti-cracking properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a chemical equation for preparing an oxirane-terminated resin using the catalyst DBTDL. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the drawings in the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0036] Example 1

[0037] 1. Preparation of Oxirane-Terminated Resin

[0038] S1. Pretreat 10 mmol of castor oil-modified diol (URIC AC009 from Ito, Japan) by dehydration in a vacuum drying oven at 110 °C. Subsequently, add 0.1 g of dibutyltin dilaurate (DBTDL), and then, under an inert gas atmosphere, add 10.1 mmol of diphenylmethane diisocyanate and react at 70 °C for 2 h to obtain an isocyanate-terminated prepolymer;

[0039] S2. Subsequently, add 20.4 mmol of 3-ethyl-3-oxetanemethanol and react at 80 °C for 3 h to obtain an oxacyclic ring-terminated resin.

[0040] 2. Preparation of the adhesive

[0041] The materials used for preparing the adhesive and their mass fractions are shown in Table 1. Weigh the above materials according to the mass fractions, stir them evenly, and then perform vacuum degassing to obtain the adhesive.

[0042] Table 1. Composition for preparing the adhesive in this example

[0043]

[0044] Comparative Example 1

[0045] This comparative example prepares an oxacyclic ring-modified resin with reference to the formula provided in Example 1. The difference from Example 1 is that in this comparative example, the method of first mixing oligomeric diol and 3-ethyl-3-oxetanemethanol and then adding diisocyanate is used to prepare the oxacyclic ring-modified resin. Except for the above difference, the operating steps for preparing the adhesive in this comparative example are strictly the same as those in Example 1. Specifically, the method for preparing the oxacyclic ring-modified resin is as follows:

[0046] Weigh the materials according to the formula provided in Example 1. Subsequently, mix URIC AC009, DBTDL, and 3-ethyl-3-oxetanemethanol, raise the temperature to 70 °C, and then start dropping diphenylmethane diisocyanate while reacting for 2 h. Subsequently, control the temperature at 80 °C and react for 3 h, then stop heating the reaction to obtain the oxacyclic ring-modified resin.

[0047] Comparative Example 2

[0048] This comparative example prepares an oxacyclic ring-modified resin with reference to the formula provided in Example 1. The difference from Example 1 is that in this comparative example, the method of first mixing diisocyanate and 3-ethyl-3-oxetanemethanol for reaction and then adding oligomeric diol is used to prepare the oxacyclic ring-modified resin. Except for the above difference, the operating steps for preparing the adhesive in this comparative example are strictly the same as those in Example 1. Specifically, the method for preparing the oxacyclic ring-modified resin is as follows:

[0049] Weigh the materials according to the formula provided in Example 1. Subsequently, mix diphenylmethane diisocyanate, DBTDL, and 3-ethyl-3-oxetanemethanol, control the temperature at 70 °C and react for 2 h. Then add URIC AC009, continue to control the temperature at 80 °C and react for 3 h. Stop heating the reaction to obtain the oxacyclic modified resin.

[0050] Comparative Example 3

[0051] In this comparative example, the oxacyclic modified resin was prepared with reference to the formula provided in Example 1. The difference from Example 1 is that in this comparative example, the oxacyclic modified resin was prepared by a one-step method. Except for the above difference, the operating steps for preparing the adhesive in this comparative example were strictly the same as those in Example 1. Specifically, the method for preparing the oxacyclic modified resin is as follows:

[0052] Weigh the materials according to the formula provided in Example 1. Subsequently, mix URIC AC009, DBTDL, diphenylmethane diisocyanate, and 3-ethyl-3-oxetanemethanol, control the temperature at 75 °C and react for 5 h. Stop heating the reaction to obtain the oxacyclic modified resin.

[0053] Comparative Example 4

[0054] In this comparative example, the modified resin was prepared with reference to the formula and method provided in Example 1. The difference from Example 1 is that in this comparative example, an equal mass fraction of n-hexanol was used to replace 3-ethyl-3-oxetanemethanol to prepare the modified resin. Except for the above difference, the operating steps for preparing the adhesive in this comparative example were strictly the same as those in Example 1.

[0055] Test Example 1

[0056] 1. Test objects

[0057] The adhesives prepared in Example 1 and Comparative Examples 1 to 3, and the cured products formed by the corresponding adhesives.

[0058] 2. Test methods

[0059] (1) Viscosity: Test using an American BROOKFIELD viscometer, with rotor No. 52.

[0060] (2) Dynamic modulus: Test using a German HAAKE MARS rheometer, at a constant frequency f = 1 Hz and a constant strain = 1%. It represents the flexibility of the adhesive.

[0061] (3) Shear strength: Test using a German HAAKE MARS rheometer, at a constant frequency f = 1 Hz and a constant strain = 1%.

[0062] (4) Glass transition temperature: The glass transition temperature (T g ) of the sample was measured using a DSC 200F3 (NETZSCH, Germany). Weighed 6 - 10 mg of the sample and placed it in an aluminum crucible. Under nitrogen protection, the sample was heated from 10°C to 300°C at a rate of 10°C / min.

[0063] (5) Test of the flexibility of the cured product: The prepared adhesive was cured on a 5 cm * 5 cm * 30 μm polypropylene film (150°C, 10 min) to obtain a cured product of 5 cm * 5 cm * 10 μm. Subsequently, using a cylindrical shaft bending tester, the polypropylene film containing the cured product was wound around a 2 mm diameter metal cylinder and pulled uniformly at 180°. Observe whether there are breaks and cracks in the cured product. The flexibility of the cured product from excellent to poor is manifested as intact without cracks, with cracks, slight material loss, material loss, large piece of material loss, and breakage in turn.

[0064] (6) Aging resistance performance test: ① Test the shear strength of the adhesive after aging treatment at 85°C / 85% RH for 1000 h; ② Test the flexibility of the cured product after aging treatment at 85°C / 85% RH for 1000 h to reflect the limits that the prepared adhesive sample and the corresponding cured product can withstand in a harsh environment of high temperature and high humidity.

[0065] 3. Test results and analysis

[0066] The test results of Test Example 1 are shown in Table 2. This test example mainly explores the influence of changes in the preparation method of the oxacyclic modified resin on the adhesive and the cured product of the adhesive using it.

[0067] In Comparative Example 1, the oxacyclic modified resin was prepared by first mixing the oligomeric diol and 3 - ethyl - 3 - oxetane methanol, and then adding the diisocyanate. The adhesive prepared using this oxacyclic modified resin has a lower cross - link density compared to that of Example 1, resulting in a decrease in the modulus of the adhesive, and further the long - term aging performance of the adhesive and its cured product becomes worse.

[0068] In Comparative Example 2, the oxacyclic modified resin was prepared by first mixing the diisocyanate and 3 - ethyl - 3 - oxetane methanol for reaction, and then adding the oligomeric diol. The adhesive prepared using this oxacyclic modified resin has a decrease in both the cross - link density and the dynamic modulus compared to that of Example 1, and the long - term aging performance of the adhesive and its cured product also becomes worse.

[0069] In Comparative Example 3, the oxacyclic modified resin was prepared by a one - step method. The adhesive prepared using this oxacyclic modified resin generates gel during the synthesis of the resin and cannot be applied to the adhesive.

[0070] However, the modified resin prepared in Comparative Example 4 does not contain an oxacycle. Compared with the adhesive prepared in Example 1, the crosslinking density and dynamic modulus of the adhesive decrease, and the long-term aging performance of the adhesive and its cured product significantly decreases.

[0071] This shows that only the oxacycle-capped resin prepared by the preparation method of Example 1 has the best performance. This is because, although Comparative Examples 1 to 3 and Example 1 use the same materials to prepare the oxacycle-modified resin, due to the different addition sequences of the oligomeric diol, diisocyanate, and 3-ethyl-3-oxetane methanol, it is impossible to ensure that the oxacycle groups are at both ends of the main chain structure of the oxacycle-modified resin, resulting in different structures of the oxacycle-modified resin, thereby affecting the yield of the oxacycle-capped resin, and further affecting the viscosity of the oxacycle-modified resin, and further affecting the modulus and flexibility of the corresponding adhesive.

[0072] Table 2. Test results of Test Example 1

[0073]

[0074] Example 2

[0075] Based on the test results of Test Example 1, the oxacycle-capped resin prepared by the preparation method of Example 1 has the best performance for the corresponding adhesive and the cured product of the adhesive. Therefore, in this example, Treatment Group 1B is set according to Example 1. In addition, each treatment group and control group in this example refer to the formula and method for preparing the oxacycle-capped resin of Treatment Group 1B, and different treatment groups and control groups are set with the molar ratio of the isocyanate functional group of the diisocyanate to the hydroxyl functional group of the oligomeric diol in S1, or the molar ratio of the hydroxyl functional group of 3-ethyl-3-oxetane methanol to the isocyanate functional group of the isocyanate in S2 as variables. The variables of each treatment group and control group in this example are shown in Table 3. And, each treatment group and control group in this example refer to Example 1 to prepare the adhesive.

[0076] Table 3. Variables of each treatment group and control group in Example 2

[0077]

[0078] Test Example 2

[0079] 1. Test object

[0080] The adhesives prepared by each treatment group and control group in Example 2 and the cured products formed by the corresponding adhesives.

[0081] 2. Test method

[0082] The test is carried out with reference to the method of Test Example 1.

[0083] 3. Test Results and Analysis

[0084] The test results of Test Example 2 are shown in Table 4. This test example mainly explores the influence of the change in the molar ratio of isocyanate functional groups to hydroxyl functional groups on the corresponding adhesives and cured adhesives during the preparation of oxacyclic-capped resins.

[0085] When the content of diisocyanate is too low, as shown in Comparative Group 1B, it will lead to a decrease in the yield of isocyanate-capped prepolymers, thereby affecting the yield of the prepared oxacyclic-capped resin; moreover, the free oligomeric diol will reduce the heat resistance of the adhesive. In contrast, in Comparative Group 2B, due to the too high content of diisocyanate, the diisocyanate will undergo self-polymerization reaction, resulting in gelation of the modified resin and making it impossible to be applied to the adhesive. Therefore, whether it is Comparative Group 1B or Comparative Group 2B, judging from the test results of their corresponding adhesives and cured adhesives, when the content of diisocyanate is too low or too high, it will reduce the heat resistance of the corresponding cured adhesives.

[0086] Similarly, when the content of 3-ethyl-3-oxetane methanol is too low or too high, such as in Comparative Groups 3B - 4B, it will also lead to a decrease in the yield of the prepared oxacyclic-capped resin, thereby affecting the viscosity and dynamic modulus of the corresponding adhesive, and further affecting the flexibility and heat resistance of the cured adhesive.

[0087] From the test results of Treatment Groups 1B - 3B in Example 2, it can be found that in S1, the diisocyanate needs to maintain an appropriate content to obtain isocyanate-capped prepolymers. Similarly, in S2, 3-ethyl-3-oxetane methanol also needs to maintain an appropriate content to obtain oxacyclic-capped resins. Thus, although the viscosity and dynamic modulus of the corresponding adhesives prepared by Treatment Groups 1B - 3B fluctuate, they can still maintain a good level. Among them, the shear strength and heat resistance of the cured adhesive prepared by Treatment Group 1B are the best.

[0088] Table 4. Test Results of Test Example 2

[0089]

[0090] Example 3

[0091] Based on the test results of Test Example 2, the oxacyclic-capped resin prepared using the formulation and method of Treatment Group 1B of Example 2 has the best performance for the corresponding adhesive and cured adhesive. Therefore, in this example, Treatment Group 1C is set according to Treatment Group 1B of Example 2. In addition, for each treatment group in this example, the formulation and method for preparing the oxacyclic-capped resin are referred to those of Treatment Group 1C, and different treatment groups are set with the oligomeric diol and diisocyanate materials used in the preparation of the oxacyclic-capped resin as variables. The variables of each treatment group in this example are shown in Table 5. And, each treatment group in this example refers to Treatment Group 1B of Example 2 to prepare the adhesive.

[0092] Table 5. Variables of Each Treatment Group in Example 3

[0093] Group Oligomeric diol Diisocyanate Treatment group 1C Castor oil modified diol (URIC AC009) Diphenylmethane diisocyanate Treatment group 2C Polypropylene glycol Diphenylmethane diisocyanate Treatment group 3C Polybutene diol Diphenylmethane diisocyanate Treatment group 4C Polypropylene oxide diol (molecular weight 3000) Diphenylmethane diisocyanate Treatment group 5C Polyethylene glycol adipate diol Diphenylmethane diisocyanate Treatment group 6C Castor oil modified diol (URIC AC009) Isophorone diisocyanate Treatment group 7C Castor oil modified diol (URIC AC009) Hexamethylene diisocyanate

[0094] Comparative Example 5

[0095] This comparative example prepares the oxacyclic-capped resin with reference to the formulation and method provided by Treatment Group 1C of Example 3. The difference from Treatment Group 1C of Example 3 is that in this comparative example, an oxacyclic-capped resin is prepared by substituting diphenylmethane diisocyanate with an equal mass of URIC AC009. Except for the above difference, the operating steps for preparing the oxacyclic-capped resin and the adhesive in this comparative example are strictly the same as those of Treatment Group 1C of Example 3.

[0096] Comparative Example 6

[0097] This comparative example prepares the oxacyclic-capped resin with reference to the formulation and method provided by Treatment Group 1C of Example 3. The difference from Treatment Group 1C of Example 3 is that in this comparative example, an oxacyclic-capped resin is prepared by substituting URIC AC009 with an equal mass of diphenylmethane diisocyanate. Except for the above difference, the operating steps for preparing the oxacyclic-capped resin and the adhesive in this comparative example are strictly the same as those of Treatment Group 1C of Example 3.

[0098] Comparative Example 7

[0099] This comparative example prepares the oxacyclic-capped resin with reference to the formulation and method provided by Treatment Group 1C of Example 3. The difference from Treatment Group 1C of Example 3 is that in this comparative example, an oxacyclic-capped resin is prepared by substituting URIC AC009 with an equal mass of poly(propylene oxide) glycol (molecular weight 7000). Except for the above difference, the operating steps for preparing the oxacyclic-capped resin and the adhesive in this comparative example are strictly the same as those of Treatment Group 1C of Example 3.

[0100] Test Example 3

[0101] 1. Test Object

[0102] The adhesives prepared by Treatment Groups 1C to 7C of Example 3 and Comparative Examples 5 to 7, and the cured products formed by the corresponding adhesives.

[0103] 2. Test method

[0104] The test was carried out according to the method of Reference Test Example 1.

[0105] 3. Test results and analysis

[0106] The test results of Test Example 3 are shown in Table 6. This test example mainly explores the influence of the changes in the materials for preparing the oxacyclic ring-terminated resin on the adhesive and the cured product of the adhesive. Among them, when preparing the oxacyclic ring-modified resin without using the oligomeric diol or diisocyanate, as shown in Comparative Examples 5 to 6, the performance of the corresponding adhesive drops rapidly. In particular, for the adhesive prepared in Comparative Example 5, since Comparative Example 5 contains an excessive amount of free oligomeric diol, the heat resistance of the adhesive is significantly reduced; while in Comparative Example 6, due to the self-polymerization reaction of the isocyanate, the resulting modified resin gels and cannot be applied to the adhesive. In addition, when using the polymeric diol to prepare the oxacyclic ring-modified resin, as shown in Comparative Example 7, adding the prepared oxacyclic ring-modified resin to the adhesive will cause the heat resistance and anti-aging performance of the adhesive to decline.

[0107] The oxacyclic ring-terminated resins prepared by Treatment Groups 1C to 5C of Example 3 from different oligomeric diols have fluctuations in the performance of the corresponding adhesives prepared. This is because the oligomeric diols containing different functional groups will form oxacyclic ring-terminated resins with different functional group main chains. However, the performance of the adhesives prepared by Treatment Groups 1C to 5C of Example 3 still remains at a good level. Similarly, Treatment Group 1CC and Treatment Groups 6C to 7C of Example 3 are oxacyclic ring-terminated resins prepared from the preferred different diisocyanates, and the corresponding adhesives can also maintain good bonding performance and flexibility. Among them, in Treatment Groups 1C to 7C of Example 3, Treatment Group 1C has the best overall performance.

[0108] Therefore, it can be confirmed through this test example that the oxacyclic ring-terminated resin prepared by using the oligomeric diol with a molecular weight of 500 to 3000 and the preferred diisocyanate can provide a lower modulus and good flexibility for the adhesive, can improve the phenomenon that the epoxy adhesive is prone to cracking after curing, and can achieve simultaneous enhancement of toughness and heat resistance.

[0109] Table 6. Test results of Test Example 3

[0110]

[0111]

[0112] Example 4

[0113] Treatment Group 1D

[0114] Treatment Group 1D of Example 4 prepared oxacyclic-capped resin and adhesive according to the formula and method provided in Example 1.

[0115] Treatment Groups 2D - 5D of Example 4 prepared oxacyclic-capped resin and adhesive with reference to the formula and method provided by Treatment Group 1D. Different from Treatment Group 1D of Example 4, Treatment Groups 2D - 5D of Example 4 used the mass fraction of the oxacyclic-capped resin used in preparing the adhesive as a variable, and the variables are shown in Table 7. Except for the above differences, the operating steps for Treatment Groups 2D - 5D of Example 4 to prepare oxacyclic-capped resin and adhesive were strictly the same as those of Treatment Group 1D.

[0116] Table 7. Variables of Treatment Groups 1D - 5D of Example 4

[0117] Group Oxacyclic end-capped resin / parts Treatment group 1D 50 Treatment group 2D 20 Treatment group 3D 80 Treatment group 4D 100 Treatment group 5D 120

[0118] Comparative Example 8

[0119] This comparative example prepared adhesive with reference to the formula and method provided by Treatment Group 1D of Example 4. Different from Treatment Group 1D of Example 4, this comparative example replaced the oxacyclic-capped resin with 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate: bis((3,4-epoxycyclohexyl)methyl) adipate: OXT-101 = 5:3:1 by mass fraction to prepare the adhesive. Except for the above differences, the operating steps for this comparative example to prepare oxacyclic-capped resin and adhesive were strictly the same as those of Treatment Group 1D of Example 4.

[0120] Comparative Example 9

[0121] This comparative example prepared adhesive with reference to the formula and method provided by Treatment Group 1D of Example 4. Different from Treatment Group 1D of Example 4, this comparative example replaced the oxacyclic-capped resin with rubber toughened epoxy resin (grade MX553) by equal mass fraction to prepare the adhesive. Except for the above differences, the operating steps for this comparative example to prepare oxacyclic-capped resin and adhesive were strictly the same as those of Treatment Group 1D of Example 4.

[0122] Test Example 4

[0123] 1. Test Objects

[0124] The adhesives prepared by Treatment Groups 1D - 5D of Example 4 and Comparative Examples 8 - 9, and the cured products formed by the corresponding adhesives.

[0125] 2. Test Methods

[0126] Conduct the test according to the method of Reference Test Example 1.

[0127] 3. Test Results and Analysis

[0128] The test results of Test Example 4 are shown in Table 8. This test example mainly explores the influence of the change in the material content during the preparation of the adhesive on the adhesive itself and the cured product of the adhesive. As the mass fraction of the oxetane-capped resin used in the adhesive gradually increases, as shown in Treatment Groups 1D to 5D, the viscosity and dynamic modulus of the adhesives corresponding to Treatment Groups 1D to 5D show a trend of first decreasing and then increasing. Their heat resistance and anti-aging performance remain in a relatively good state, while the toughness of the cured product shows a trend of first increasing and then decreasing. This is because by regulating the content of the oxetane-capped resin, it is possible to affect the viscosity, dynamic modulus, and toughness of the adhesive, but it has little effect on the heat resistance and anti-aging performance of the adhesive. This is because the alicyclic epoxy resin and oxetane monomer provided by the present invention can maintain the good heat resistance and anti-aging performance of the adhesive, and the oxetane-capped resin provided by the present invention has little effect on the heat resistance and anti-aging performance of the adhesive. Through the test results of Treatment Groups 1D to 5D, it can be found that the adhesive and the cured product of the adhesive prepared in Treatment Group 1D have the best performance.

[0129] In Comparative Example 8, since no oxetane-capped resin is added to the adhesive, the dynamic modulus of the adhesive increases significantly, indicating that the flexibility of the adhesive drops severely, and its cured product is prone to cracking after aging. In Comparative Example 9, when using an equal mass fraction of rubber-toughened epoxy resin to replace the oxetane-capped resin to prepare the adhesive, the viscosity and dynamic modulus of the adhesive increase significantly, indicating that the processing performance of the adhesive is greatly affected, and the flexibility of the adhesive decreases significantly.

[0130] Therefore, through this test, it can be confirmed that the adhesive provided by the present invention can significantly reduce the modulus of the adhesive and enhance the toughness of the adhesive by combining the oxetane-capped resin, alicyclic epoxy resin, and oxetane monomer. Moreover, after the oxetane-capped resin provided by the present invention is added to the epoxy resin adhesive, it will not reduce the processing performance and heat resistance of the adhesive.

[0131] In addition, compared with a high-toughness and high-heat-resistant alicyclic epoxy resin disclosed in the prior art CN 113897027 A, whose curing conditions are: 100°C × 2h + 140°C × 2h + 180°C × 2h, the adhesive provided by the present invention only needs to be cured at 150°C for 10 minutes. Therefore, the adhesive provided by the present invention has the characteristics of high heat resistance, high flexibility, and rapid curing.

[0132] Table 8. Test Results of Test Example 4

[0133]

[0134] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An oxygen heterocycle terminated resin, It is characterized in that The preparation method of the oxygen heterocycle terminated resin comprises the following steps: S1. polymerizing an oligomer diol and a diisocyanate at 70-75° C. until the oligomer diol is completely reacted, thereby obtaining an isocyanate-terminated prepolymer, wherein the molecular weight of the oligomer diol is 500-3000, and the feeding ratio of the oligomer diol and the diisocyanate is determined according to the molar ratio of the isocyanate functional group of the isocyanate to the hydroxyl functional group of the oligomer diol being 1.02-1.1; S2. Then, oxetane alcohol is added to the prepolymer, and the mixture is reacted at 80-85° C. for 1-4 hours to obtain the oxetane-terminated resin, wherein the feed ratio of the prepolymer to the oxetane alcohol is determined according to a molar ratio of the hydroxyl functional group of the oxetane alcohol to the isocyanate functional group of the prepolymer of 1.02-1.1; The oxetanol includes at least one of 3-oxetanol, 3-ethyl-3-oxetanol, [3-(propan-2-yl)oxetan-3-yl]methanol, and 3-isopropyloxetan-3-ol.

2. The oxygen heterocycle terminated resin according to claim 1, It is characterized in that The oligomer diol includes at least one of polyester diol, polyether diol, polyolefin diol, vegetable oil diol and epoxy resin diol.

3. The oxygen heterocycle terminated resin according to claim 2, It is characterized in that The functionality of the oligomer diol is 2-3, and the hydroxyl value is 200-500 mgKOH / g.

4. The oxygen heterocycle terminated resin according to claim 1, It is characterized in that The diisocyanate includes at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate and hexamethylene diisocyanate.

5. An adhesive, It is characterized in that The raw materials for preparing the adhesive include the oxygen heterocycle terminated resin as described in any one of claims 1 to 4; wherein, calculated by weight, the raw materials for preparing the adhesive include 50 to 100 parts of epoxy resin, 10 to 100 parts of oxetane monomer, 20 to 100 parts of the oxygen heterocycle terminated resin, and 0.1 to 2 parts of a thermally initiated cationic curing agent.

6. The adhesive according to claim 5, It is characterized in that The epoxy resin includes an alicyclic epoxy resin, wherein the alicyclic epoxy resin includes at least one of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexyl methyl ester, poly[(2-epoxyethylene)-1,2-cyclohexanediol] 2-ethyl-2-(hydroxymethyl)-1,3-propylene glycol ether, bis((3,4-epoxycyclohexyl)methyl)adipate, tetrahydroindene diepoxide, 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexyl methyl methacrylate, 3,4-epoxycyclohexyl methacrylate, and vinylcyclohexene dioxide.

7. The adhesive according to claim 6, It is characterized in that The oxetane monomer includes at least one of 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane, 3,3'-(oxybis(methylene))bis(3-ethyl)oxetane, and 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene.

8. The adhesive according to claim 6, wherein, the thermal cationic curing agent includes at least one of aryl diazonium salt curing agents, aryl iodonium salt curing agents, aryl sulfonium salt curing agents, and allene-ion complex curing agents.

9. An adhesive layer, wherein, the adhesive layer is a cured product of the adhesive according to any one of claims 5 to 8.

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