A phenoxy resin containing side carbamate groups and its synthesis method

Abstract

The present invention belongs to the technical field of adhesives, and specifically relates to a phenoxy resin containing side carbamate groups and a synthesis method thereof. The phenoxy resin containing side carbamate groups is synthesized from phenoxy resin, five-membered cyclic carbonate, cysteamine, and isocyanate group-containing acrylate. Among them, the number-average molecular weight of the phenoxy resin is 8000-90000 g / mol, the five-membered cyclic carbonate is one or a mixture of ethylene carbonate, ethylene ethylene carbonate, propylene carbonate, and glycerol carbonate, and the isocyanate group-containing acrylate is one or a mixture of two of ethyl isocyanate acrylate and isocyanatoethyl methacrylate. The phenoxy resin containing side carbamate groups of the present invention has lap shear strengths greater than 21.5 MPa, 25.8 MPa, and 18.5 Mpa for aluminum alloy, steel plate, and epoxy substrate respectively, and a Vicat softening temperature higher than 95 °C. The improvement of heat resistance enables the phenoxy resin to cope with high-temperature service environments, and there are no by-products in the synthesis route, no purification is required, and the synthesis process is simple and efficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesives, and particularly relates to a phenoxy resin containing side carbamate groups and a synthesis method thereof. Background Art

[0002] Phenoxy resin is an amorphous high molecular polyhydroxy ether prepared by the condensation reaction of bisphenol A and epichlorohydrin. The molecular weight of phenoxy resin is much higher than that of liquid epoxy resin. Two epoxy groups are distributed at the ends of the main chain, and their reaction possibility can be ignored in terms of reaction kinetics. Even if a crosslinking agent is introduced into the blend system, it will not cure to form a crosslinked network structure like epoxy resin. Therefore, it is a tough thermoplastic material with high impact strength and can be used for toughening and modification of thermosetting materials.

[0003] The structure of phenoxy resin determines its unique performance characteristics. The amorphous aggregate state gives it excellent toughness, and it can be used as a toughening modifier for other thermosetting materials. In any application scenario where epoxy resin is used to improve toughness, and in applications where the adhesion strength needs to be improved in coatings, such as coil steel coatings, beverage can coatings, metal can wall coatings, credit card magnetic card coatings, enameled wire coatings, etc., and also in carbon fiber composites, fiberglass prepregs, textile fabric laminations, copper clad laminates and printed circuit boards, etc., phenoxy resin can be used for modification. However, the glass transition temperature of phenoxy resin is not high, generally between 70 and 100 °C, and the Vicat softening temperature is between 50 and 85 °C. The processing temperature of many carbon fiber composites is relatively high, and phenoxy resin needs to be modified to a certain extent in the high-temperature processing process of carbon fiber composites, and the process is relatively complex. Therefore, its application in high-end composites is restricted to a certain extent. Phenoxy resin has an active hydroxyl structure and is used as a hot-melt adhesive, acting on various substrates such as metals, glass, plastics, wood, textile fabrics, etc., with excellent adhesion strength, and the shear strength to aluminum alloy substrates is as high as 23 MPa. Considering the properties of low creep and low deformation required under long-term high-temperature service conditions, the performance of phenoxy resin is insufficient. Therefore, it is necessary to explore new ways to improve the Vicat softening temperature from the perspective of molecular design while maintaining a relatively high level of adhesion ability, and achieving this goal is challenging and has industrial application value. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a phenoxy resin containing side carbamate groups and a synthesis method thereof.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A phenoxy resin containing side carbamate groups is synthesized from phenoxy resin, five-membered ring carbonate, cysteamine, and isocyanate group-containing acrylate, and its chemical structural general formula is

[0007]

[0008] Among them, R1 is H or CH3, R2 is H, CH3, CH=CH2 or CH2OH, the value of n depends on the number-average molecular weight of the phenoxy resin, and the x / n ratio is 0.05 to 0.25.

[0009] Preferably, the number-average molecular weight of the phenoxy resin is 8000 to 90000 g / mol.

[0010] Preferably, the five-membered cyclic carbonate is one or a mixture of ethylene carbonate, ethylene ethylene carbonate, propylene carbonate, glycerol carbonate, etc.

[0011] Preferably, the isocyanate group-containing acrylate is one or a mixture of ethyl isocyanate acrylate and isocyanatoethyl methacrylate.

[0012] The present invention also provides a method for synthesizing the phenoxy resin containing side carbamate groups, comprising the following steps:

[0013] (1) Put 1.0 molar equivalent of five-membered cyclic carbonate into the reaction kettle, dissolve 1.0 molar equivalent of cysteamine in solvents such as tetrahydrofuran, chloroform or N,N-dimethylformamide, and put it into the reaction kettle. Stir at 25-80 °C for at least 4 hours until the characteristic peak of the five-membered cyclic carbonate at 1800 cm -1 disappears in the Fourier transform infrared spectrum, and stop stirring for standby;

[0014] (2) Dissolve 1.0 molar equivalent of phenoxy resin in the redistilled solvents of tetrahydrofuran, chloroform or N,N-dimethylformamide, put it into the reaction kettle, heat up to 90-100 °C, and put a certain amount of isocyanate group-containing acrylate according to the x / n ratio. Add 5-10 ppm of the catalyst dibutyltin dilaurate based on the total mass of the two reactants, introduce high-purity nitrogen and cool backflow, and react for at least 6 hours until the NCO characteristic peak at 2260 cm -1 disappears in the Fourier transform infrared spectrum;

[0015] (3) According to the x / n ratio, add a certain amount of the product of step (1) to the product of step (2), add 100-500 ppm of the catalyst diazabicyclo based on the total mass of the reactants, control the temperature at 60-90 °C, introduce high-purity nitrogen for protection, and react for 12-24 hours to remove the solvent to obtain the phenoxy resin containing side carbamate groups.

[0016] Preferably, as measured according to GB / T7214-2008, the lap shear strength of the phenoxy resin containing side carbamate groups with respect to aluminum alloy, steel plate, and epoxy substrate is greater than 21.5 MPa, 25.8 MPa, and 18.5 Mpa respectively. As measured according to GB / T1633, the Vicat softening temperature of the phenoxy resin containing side carbamate groups is higher than 95 °C.

[0017] The beneficial effects of the present invention are as follows:

[0018] (1) The synthesis route has typical atom - economic characteristics, without by - products, no need for purification, and the synthesis process is simple and efficient.

[0019] (2) Each side group contains two carbamate groups, one hydroxyl group, and one ester group. Abundant hydrogen bonds are formed between molecular chains, associating at room temperature and dissociating at high temperature, which can effectively improve the adhesion ability of the modified phenoxy resin hot - melt adhesive. The carbamate groups undergo microphase separation to form hard - segment domains, significantly increasing the Vicat softening temperature. The improvement in heat resistance enables the phenoxy resin to cope with high - temperature service environments.

[0020] Specific implementation examples

[0021] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0022] The raw materials used in the experiments of the examples and comparative examples of the present invention are as follows, but are not limited to the following raw materials. The present invention only uses the following raw materials as specific examples to further specifically illustrate the effects of the phenoxy resin containing side carbamate groups described in the present invention.

[0023] Phenoxy resin: PKHB, number - average molecular weight is 9500 g / mol, Tg(DSC) 84 °C, PKHJ, number - average molecular weight is 16000 g / mol, from InChem, USA.

[0024] Five - membered ring carbonate: ethylene carbonate EC, from Shandong Taixi Chemical Industry.

[0025] Cysteamine, from Shanghai Macklin.

[0026] Isocyanate - group - containing acrylate: ethyl isocyanate acrylate AOI, from Zhangjiagang Top Chemical Industry.

[0027] The present invention sets Examples 1 - 6 and Comparative Examples 1 - 6, and their formulations are shown in Table 1:

[0028] Table 1

[0029]

[0030] Examples 1 - 6, Comparative Examples 2 - 3, and Comparative Examples 5 - 6 are synthesized according to the following process:

[0031] (1) Charge the five-membered cyclic carbonate EC into the reaction kettle. Dissolve cysteamine in the redistilled solvent of N,N-dimethylformamide and charge it into the reaction kettle. Stir at 60 °C for 6 hours. When the characteristic peak of the five-membered cyclic carbonate at 1800 cm -1 disappears in the Fourier transform infrared spectrum, stop stirring and set aside;

[0032] (2) Dissolve the phenoxy resin in the redistilled solvent of N,N-dimethylformamide, charge it into the reaction kettle, heat up to 95 °C, charge a certain amount of isocyanate ethyl acrylate AOI according to the x / n ratio, add 10 ppm of the catalyst dibutyltin dilaurate based on the total mass of the two reactants, introduce high-purity nitrogen and carry out water-cooled reflux, and react for 8 hours. When the NCO characteristic peak at 2260 cm -1 disappears in the Fourier transform infrared spectrum;

[0033] (3) According to the x / n ratio, add a certain amount of the product of step (1) to the product of step (2), add 300 ppm of the catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene based on the total mass of the reactants, control the temperature at 80 °C, introduce high-purity nitrogen for protection, and react for 12 hours. Remove the solvent to obtain the phenoxy resin containing side carbamate groups.

[0034] The finished products prepared in the examples and comparative examples of the present invention are melt-sized to make samples at 180 °C, and the lap shear strength is measured according to the method specified in GB / T7124-2008.

[0035] The performance evaluation results of Examples 1-6 and Comparative Examples 1-6 of the present invention are shown in Table 2:

[0036] Table 2

[0037]

[0038] It can be seen from Examples 1-6, Comparative Examples 1-2 and Comparative Examples 4-5 that by introducing the side carbamate group, the Vicat softening temperature is significantly increased and the bonding strength is significantly improved. However, when the introduction amount is too much, that is, when the x / n ratio exceeds 0.25, the shear strength of Comparative Examples 3 and 6 does not continue to increase, indicating that the introduction amount of the side carbamate group should be within a reasonable range to effectively improve the bonding strength.

[0039] Finally, it should be noted that the above examples 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. A phenoxy resin containing side carbamate groups, characterized in that, Synthesized from phenoxy resin, five-membered cyclic carbonate, cysteamine, and isocyanate group-containing acrylate; The general chemical structural formula thereof is wherein, R1 is H or CH3, R2 is H, CH3, CH=CH2 or CH2OH, the value of n depends on the number-average molecular weight of the phenoxy resin, and the x / n ratio is 0.05 to 0.

25.

2. The phenoxy resin containing a side carbamate group as described in claim 1, wherein The number-average molecular weight of the said phenoxy resin is 8000 to 90000 g / mol.

3. The phenoxy resin containing a side carbamate group as described in claim 1, wherein The said five-membered cyclic carbonate is one or a mixture of more than one of ethylene carbonate, ethylene ethylenecarbonate, propylene carbonate, and glycerol carbonate.

4. The phenoxy resin containing side carbamate groups as described in claim 1, characterized in that, The said isocyanate group-containing acrylate is one or a mixture of two of ethyl isocyanate acrylate and isocyanatoethyl methacrylate.

5. A method for synthesizing a phenoxy resin containing a side carbamate group as described in any one of claims 1 to 4, characterized in that, It includes the following steps: (1) Charge 1.0 molar equivalent portion of the five-membered cyclic carbonate into a reaction kettle. Dissolve 1.0 molar equivalent portion of cysteamine in a solvent such as tetrahydrofuran, chloroform or N,N-dimethylformamide, and charge it into the reaction kettle. Stir at 25-80 °C for at least 4 hours until the characteristic peak of the five-membered cyclic carbonate at 1800 cm -1 disappears in the Fourier transform infrared spectrum, and then stop stirring for standby; (2) Dissolve 1.0 molar equivalent of phenoxy resin in a solvent of freshly distilled tetrahydrofuran, chloroform or N,N-dimethylformamide, put it into a reaction kettle, heat up to 90 - 100 °C, add a certain amount of isocyanate group-containing acrylate according to the x / n ratio, add 5 - 10 ppm of dibutyltin dilaurate as the catalyst based on the total mass of the two reactants, introduce high-purity nitrogen and cool it with water for reflux, and react for at least 6 hours until the NCO characteristic peak at 2260 cm -1 disappears in the Fourier transform infrared spectrum; (3) According to the x / n ratio, add a certain amount of the product of step (1) to the product of step (2), add 100 to 500 ppm of the catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene based on the total mass of the reactants, control the temperature at 60 to 90 °C, introduce high-purity nitrogen for protection, react for 12 to 24 hours, and remove the solvent to obtain the phenoxy resin containing side carbamate groups.

6. The phenoxy resin containing a side carbamate group according to any one of claims 1 to 4, characterized in that Determined according to GB / T 7214-2008, the lap shear strength of the said phenoxy resin containing side carbamate groups for aluminum alloy, steel plate, and epoxy substrate is respectively greater than 21.5 MPa, 25.8 MPa, and 18.5 Mpa.

7. The phenoxy resin containing a side carbamate group according to any one of claims 1 to 4, characterized in that, Determined according to GB / T 1633, the Vicat softening temperature of the said phenoxy resin containing side carbamate groups is higher than 95 °C.

Images