Active cationic epoxy flexibilizer and synthesis method thereof

Abstract

According to the active cationic epoxy flexibilizer and the synthesis method thereof, flexible hydrophobic groups are grafted to oxetane molecules to form the active flexibilizer, the active flexibilizer can react with matrix cationic epoxy resin groups, and the initiation reaction speed is not reduced. The active cationic epoxy flexibilizer prepared by the invention can significantly improve the bonding strength, high temperature and high humidity resistance and high and low temperature impact resistance, and a product prepared from the active cationic epoxy flexibilizer has excellent flexibility, high and low temperature impact resistance and high and high temperature and high humidity resistance while maintaining high strength.

Description

Technical Field

[0001] The invention relates to an active cationic epoxy toughening agent and a synthesis method thereof, and belongs to the field of polymer adhesives. Background Art

[0002] Cationic epoxy adhesives, as an important class of thermosetting polymer adhesive materials, have the characteristics of low curing shrinkage, low residual stress, high bulk strength and modulus, and delayed curing. They are widely used in composite materials, electronic packaging, automobiles, and architectural coatings. However, due to the high hardness, poor toughness, poor high temperature and humidity resistance, and poor high and low temperature impact performance of conventional cationic epoxy adhesives after curing, they are limited in practical applications. Conventional toughening methods include adding polyether sulfone, liquid carboxyl-terminated nitrile rubber, polysulfide rubber, liquid hydroxyl-terminated polybutadiene and other rubbers, acrylate core-shell polymers, silicone core-shell polymers, polyurethane acrylates, polyols and other inert toughening agents, but the defects of these inert toughening agents are that while increasing toughness, the bulk strength, bonding strength, high temperature and humidity resistance, and high and low temperature impact resistance are greatly reduced, and the groups of some toughening agents and the catalysts used in the synthesis process will cause the cationic initiator to be poisoned, resulting in a significant reduction in the initiation rate, affecting production efficiency. The active cationic epoxy toughening agent of the present invention can solve the above problems well. Summary of the invention

[0003] In order to solve the deficiencies of the prior art, the present invention provides an active cationic epoxy toughening agent and a synthesis method thereof, wherein the product prepared by the active cationic epoxy toughening agent has excellent flexibility, high and low temperature impact resistance and high temperature and humidity resistance while maintaining high strength.

[0004] The technical solution of the present invention to solve the above problems is as follows: A method for synthesizing an active cationic epoxy toughening agent comprises the following steps: the first step: adding terminal hydroxyl oxetane and fatty acid into a reaction kettle at a molar ratio of hydroxyl to carboxyl of 1-1.2:1, then adding 0.005%-1% of the total weight of a catalyst, reacting at 120-230° C. for 2-4 hours, and then decompressing and dehydrating to react to an acid value of ≤0.1 mgKOH / g to obtain a product.

[0005] Furthermore, the terminal hydroxyl oxetane refers to a substance containing at least one cyclobutyloxy group and one hydroxyl group in its molecular structure, preferably an oxetane containing a primary hydroxyl group in its molecular structure.

[0006] Furthermore, the fatty acid includes castor oil fatty acid, palmitoleic acid, linoleic acid, and aliphatic dimer acid.

[0007] Furthermore, the catalyst includes titanates, such as tetrabutyl titanate.

[0008] Furthermore, the use of the active cationic epoxy toughening agent in the epoxy system formulation includes, by weight, 1%-80% of the active cationic epoxy toughening agent, 20-99% of oxetane and / or alicyclic epoxy, and 0.5-5% of the cationic photoinitiator or cationic thermal initiator.

[0009] The beneficial effect of adopting this technical solution is that the flexible hydrophobic group is grafted onto the oxetane molecule to form an active toughening agent, which can react with the matrix cationic epoxy resin group without reducing the initiation reaction rate. At the same time, we found that the active toughening agent can significantly improve the bonding strength, high temperature and high humidity resistance, and high and low temperature impact resistance. DETAILED DESCRIPTION

[0010] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0011] Example 1 198g of 3-ethyl-3-(4-hydroxybutoxymethyl)oxetane (HBOX) from UBE, Japan, 280g of dehydrated castor oil fatty acid (DCO-FA-K) from Ito Oil, Japan, and 0.1g of tetrabutyl titanate were added to the reactor in sequence, and reacted at 140°C for 2h, and then vacuum dehydrated at 180°C to continue the reaction until the acid value was ≤0.1mgKOH / g, to obtain an active cationic epoxy toughening agent. After cooling to room temperature, 1115g of alicyclic epoxy CELLOXIDE2021P from Daicel, Japan was added to the above active toughening agent, and 16g of photocationic initiator CPI200K from SAN-APRO, Japan was added in a light-proof environment, and stirred evenly in a light-proof environment, degassed, and the material was discharged for use.

[0012] Example 2 386g of 3-ethyl-3-(4-hydroxybutoxymethyl)oxetane (HBOX) from UBE, Japan, 561g of dimer acid (UNIDYME 14) from Kraton, USA, and 0.2g of tetrabutyl titanate were added to the reactor in sequence, and reacted at 140°C for 2h, and then vacuum dehydrated at 180°C to continue the reaction until the acid value was ≤0.1mgKOH / g, to obtain an active cationic epoxy toughening agent. After cooling to room temperature, 2210g of alicyclic epoxy CELLOXIDE 2021P from Daicel, Japan was added to the above active toughening agent, and 32g of photocationic initiator CPI200K from SAN-APRO, Japan was added in a light-proof environment, and stirred evenly in a light-proof environment, degassed, and discharged for use.

[0013] Comparative Example 1 240g of 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane (OXT-212) from Nagase, 280g of dehydrated castor oil fatty acid (DCO-FA-K) from Ito Oil Co., Ltd., and 0.1g of tetrabutyl titanate were added to the reactor in sequence, and stirred evenly at room temperature to obtain the product. 1213g of alicyclic epoxy CELLOXIDE2021P from Daicel Corporation of Japan was added to the above product, and 18g of photocationic initiator CPI200K from SAN-APRO Corporation of Japan was added in a light-proof environment, and stirred evenly in a light-proof environment, degassed, and the material was discharged for use.

[0014] The performance of the active cationic epoxy toughening agent of the present invention was tested by the following test.

[0015] Ontology performance Bending strength and bending elongation. The sample preparation and curing method is high-pressure mercury lamp ultraviolet light initiation curing (the same below).

[0016] 2. Adhesive properties The bonding substrate is PC / PC, the bonding area is 12.5mm×25mm, and the thickness of the adhesive layer is 0.1mm.

[0017] 1. Initial shear strength test (SS, the same below).

[0018] 2. High and low temperature impact test (TC): The sample is placed in (-40℃ / 30min-85℃ / 30min) for 200 cycles, and then placed at room temperature for 24h to test the shear strength.

[0019] 3. High temperature and high humidity test (HTHH): Place the sample at 85℃, 85%RH for 1000h, then place it at room temperature for 24h to test the shear strength.

[0020] Table 1 Comparative test results of the embodiments and comparative examples.

[0021]

[0022] It can be seen from the above results that the active cationic epoxy toughening agent of the present invention has higher flexural strength, flexural elongation and bonding strength than the inert toughening agent, has less attenuation of bonding strength after high and low temperature impact and high temperature and high humidity aging, and has higher reliability.

[0023] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An active cationic epoxy toughening agent, the synthesis method of which comprises the following steps: adding terminal hydroxyl oxetane and fatty acid into a reaction kettle at a hydroxyl group to carboxyl group molar ratio of 1-1.2:1, then adding 0.005%-1% of the total weight of a catalyst, reacting at 120-230° C. for 2-4 hours, and then decompressing and dehydrating to react to an acid value of ≤0.1 mgKOH / g to obtain an active cationic epoxy toughening agent.

2. An active cationic epoxy toughening agent according to claim 1, characterized in that: The terminal hydroxyl oxetane refers to a substance containing at least one cyclobutyloxy group and one hydroxyl group in its molecular structure, and preferably an oxetane containing a primary hydroxyl group in its molecular structure.

3. An active cationic epoxy toughening agent according to claim 1, characterized in that: The oily acid includes castor oil fatty acid, palmitoleic acid, linoleic acid, and aliphatic dimer acid; and the catalyst is tetrabutyl titanate.

4. Use of the active cationic epoxy toughening agent as claimed in claim 1 in the preparation of epoxy system adhesives.

5. The use according to claim 4, characterized in that: The epoxy system adhesive comprises the following components in parts by weight: 1%-80% of active cationic epoxy toughener, 20-99% of oxetane and / or alicyclic epoxy, and 0.5-5% of cationic photoinitiator or cationic thermal initiator.

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