Active cationic epoxy flexibilizer and method for its synthesis

Abstract

The application provides an active cationic epoxy toughening agent and a synthesis method thereof, a flexible hydrophobic group is grafted to an oxetane molecule to form the active toughening agent, the active toughening agent can react with a matrix cationic epoxy resin group, and the initiation reaction speed is not reduced. The active cationic epoxy toughening agent prepared by the application can significantly improve bonding strength, high-temperature and high-humidity resistance and high-temperature and low-temperature impact resistance. Products prepared by using the active cationic epoxy toughening agent have excellent flexibility, high-temperature and low-temperature impact resistance and high-temperature and high-humidity resistance while maintaining high strength.

Description

TECHNICAL FIELD

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

[0002] As an important thermosetting polymer adhesive material, the cationic epoxy adhesive has the characteristics of low curing shrinkage, low residual stress, high body strength and modulus, and delayed curing, and is widely applied to the fields of composite materials, electronic packaging, automobile and building coatings. However, the conventional cationic epoxy adhesive is limited in practical application due to the defects of high hardness, poor toughness, poor high-temperature and high-humidity resistance and poor high-temperature and low-temperature impact resistance after curing. The conventional toughening methods include adding inert toughening agents such as polyether sulfone, liquid carboxyl-terminated nitrile rubber, polythio rubber, liquid hydroxyl-terminated polybutadiene, acrylate core-shell polymer, silicone core-shell polymer, polyurethane acrylate and polyol. However, the defects of these inert toughening agents are that the body strength, bonding strength, high-temperature and high-humidity resistance and high-temperature and low-temperature impact resistance are greatly reduced while the toughness is increased, and the groups of some toughening agents and the catalysts used in the synthesis process cause the poisoning of the cationic initiator, thereby greatly reducing the initiation rate and affecting the production efficiency. The active cationic epoxy toughening agent can well solve the above problems. SUMMARY

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

[0004] The technical scheme for solving the above problems is as follows:

[0005] The synthesis method of the active cationic epoxy toughening agent comprises the following steps: in the first step, hydroxyl-terminated oxetane and oil fatty acid are added into a reaction kettle according to a hydroxyl-carboxyl molar ratio of 1-1.2:1, then 0.005%-1% of a total weight of a catalyst is added, and reaction is carried out at 120-230 DEG C for 2-4 h, then dehydration reaction is carried out under reduced pressure until the acid value is less than or equal to 0.1 mgKOH / g, and the product is obtained.

[0006] Further, the hydroxyl-terminated oxetane refers to a substance containing at least one cyclobutoxy group and one hydroxyl group in the molecular structure, and preferably a primary hydroxyl group-containing oxetane.

[0007] Further, the oil fatty acid includes castor oil fatty acid, palm oil oleic acid, linoleic acid and aliphatic dimer acid.

[0008] Further, the catalyst includes titanium esters, such as tetrabutyl titanate.

[0009] Further, the application of the active cationic epoxy toughening agent in the epoxy system formula includes 1%-80% of the active cationic epoxy toughening agent, 20-99% of the oxetane and / or alicyclic epoxy, and 0.5-5% of the cationic photoinitiator or cationic thermal initiator by weight.

[0010] The beneficial effects of the technical solution are that the flexible hydrophobic group is grafted onto the oxetane molecule to form an active toughening agent, which can react with the cationic epoxy resin group of the matrix and does not reduce the initiation reaction speed. At the same time, it is found that the active toughening agent can significantly improve the bonding strength, high temperature and humidity resistance, and high and low temperature impact resistance. DETAILED DESCRIPTION

[0011] The principles and features of the application are described below, and the examples are only used to explain the application and not to limit the scope of the application.

[0012] Example 1

[0013] 198g of 3-ethyl-3-(4-hydroxybutoxymethyl)oxetane (HBOX) from Japan UBE Co., Ltd., 280g of dehydrated castor oil fatty acid (DCO-FA-K) from Japan Itoh Oil Co., Ltd., and 0.1g of tetrabutyl titanate were sequentially added to a reactor, reacted at 140℃ for 2h, and then dehydrated at 180℃ to continue the reaction until the acid value was ≤0.1mgKOH / g. After cooling to room temperature, 1115g of alicyclic epoxy CELLOXIDE 2021P from Japan Daicel Co., Ltd. was added to the above active toughening agent, 16g of photo-cationic initiator CPI200K from Japan SAN-APRO Co., Ltd. was added in a light-proof environment, and the mixture was stirred uniformly, defoamed, and discharged for standby.

[0014] Example 2

[0015] 386g of 3-ethyl-3-(4-hydroxybutoxymethyl)oxetane (HBOX) from Japan UBE Co., Ltd., 561g of dimer acid (UNIDYME 14) from the United States Cortec Co., Ltd., and 0.2g of tetrabutyl titanate were sequentially added to a reactor, reacted at 140℃ for 2h, and then dehydrated at 180℃ to continue the reaction until the acid value was ≤0.1mgKOH / g. After cooling to room temperature, 2210g of alicyclic epoxy CELLOXIDE 2021P from Japan Daicel Co., Ltd. was added to the above active toughening agent, 32g of photo-cationic initiator CPI200K from Japan SAN-APRO Co., Ltd. was added in a light-proof environment, and the mixture was stirred uniformly, defoamed, and discharged for standby.

[0016] Comparative Example 1

[0017] Into the reactor, 240 g of 3-ethyl-3-[ (2-ethylhexyloxy) methyl] oxetane (OXT-212) from Nagase Co. Ltd., 280 g of Japan Itoh Oil, Inc. dehydrated castor oil fatty acid (DCO-FA-K), 0.1 g of tetrabutyl titanate were added in sequence, stirred uniformly at room temperature, and the product was obtained. Into the above product, 1213 g of Japan Daicel Co. Ltd. cycloaliphatic epoxy CELLOXIDE 2021P, 18 g of Japan SAN-APRO Co. Ltd. photocationic initiator CPI 200K were added in a light-proof environment, stirred uniformly in a light-proof environment, defoamed, and discharged for standby.

[0018] The performance of the active cationic epoxy toughening agent of the present application was tested by the following tests.

[0019] Bulk properties

[0020] Flexural strength and flexural elongation. The sample preparation and curing mode were high-pressure mercury lamp ultraviolet light-induced curing (same below).

[0021] II. Adhesion properties

[0022] The adhesion substrate was PC / PC, the bonding area was 12.5 mm x 25 mm, and the adhesive layer thickness was 0.1 mm.

[0023] 1. Initial shear strength test (SS, same below).

[0024] 2. High-low temperature impact test (TC): the sample was placed in (-40℃ / 30min- 85℃ / 30min) 200 cycles, and then the shear strength was tested after constant temperature at room temperature for 24 h.

[0025] 3. High temperature and high humidity test (HTHH): the sample was placed in 85℃, 85% RH for 1000 h, and then the shear strength was tested after constant temperature at room temperature for 24 h.

[0026] Table 1. Comparative test results of examples and comparative examples.

[0027]

[0028] As can be seen from the above results, the active cationic epoxy toughening agent of the present application has higher flexural strength, flexural elongation and adhesion strength than the inert toughening agent, and has smaller adhesion strength attenuation after high-low temperature impact and high temperature and high humidity aging, and higher reliability.

[0029] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An active cationic epoxy toughening agent, a synthesis method comprising the following steps: adding hydroxyl-terminated oxetane and oil fatty acid in a hydroxyl and carboxyl molar ratio of 1-1.2:1 into a reaction kettle, then adding a total weight of 0.005%-1% of a catalyst, reacting at 120-230℃ for 2-4h, then dehydrating the reaction under reduced pressure to an acid value of ≤0.1mgKOH / g, to obtain the active cationic epoxy toughening agent. The hydroxyl-terminated oxetane is oxetane containing primary hydroxyl groups in the molecular structure. The oil fatty acid is selected from castor oil fatty acid, palm oil oleic acid, linoleic acid, aliphatic dimer acid; and the catalyst is tetrabutyl titanate.

2. Use of the active cationic epoxy toughening agent of claim 1 in preparing an epoxy system adhesive.

3. Use according to claim 2, characterized in that, The epoxy system adhesive comprises the following components by weight: 1%-80% of the active cationic epoxy toughening agent, 20-99% of oxetane and / or alicyclic epoxy, and 0.5-5% of a cationic photoinitiator or a cationic thermal initiator.

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