Polyurethane modified epoxy resin as well as preparation method and application thereof

Abstract

The invention provides polyurethane modified epoxy resin as well as a preparation method and application thereof. The resin comprises NCO-terminated polyurethane, an amine curing agent and epoxy resin, and the NCO-terminated polyurethane has a specific structure and is prepared by reacting dihydric phenol and / or alcohol with isocyanate with NCO functional groups larger than or equal to 2. The invention also provides a preparation method and application of the resin. According to the resin, on the premise that the mechanical property of epoxy resin is not reduced, the flexibility is improved, meanwhile, the reaction speed and the final curing degree of the resin are increased, the use of a catalyst is reduced, and the production cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and specifically relates to a polyurethane modified epoxy resin and a preparation method and application thereof. Background Art

[0002] Epoxy resin (EP) has the advantages of good bonding performance, high chemical stability, strong high and low temperature resistance and low curing shrinkage. It is a type of thermosetting resin with excellent comprehensive performance. Since it was introduced into the domestic market in the late 1950s, it has been widely used in adhesives, coatings and other fields. After curing, epoxy resin forms a highly cross-linked network structure, which leads to increased internal stress, brittleness and poor impact resistance. It needs to be toughened to improve its comprehensive application performance.

[0003] There are many methods for toughening and modifying epoxy resins, but there is a problem of incomplete compatibility between PU and EP in polyurethane (PU) modified epoxy resin (EP) materials. The amount of PU added cannot be too high, and the toughening effect is not ideal. There are two main methods for traditional polyurethane toughening and modifying epoxy resins: one is to add terminal hydroxyl polyurethane to epoxy resin for blending, and use the flexibility of polyurethane molecular chain to toughen epoxy resin; the other is to use the isocyanate group in the polyurethane structure to react with the hydroxyl group in the epoxy resin structure to achieve a significant improvement in the bonding and mechanical properties of the toughening system. Among them, the first method is physically blended, so its compatibility is not very good and cannot have high compatibility; the second method, because it uses the reaction of hydroxyl and NCO, because the hydroxyl content is small and the steric hindrance effect is obvious in macromolecular epoxy, the reaction is not sufficient, resulting in poor compatibility.

[0004] In summary, the current problem of polyurethane-modified toughened epoxy resins is still the poor compatibility between polyurethane and epoxy resin, which leads to a decrease in the mechanical strength of the toughened resin and needs to be solved urgently. Summary of the invention

[0005] In order to solve the above technical problems, one of the objects of the present invention is to provide a polyurethane modified epoxy resin, which can increase flexibility without reducing the mechanical properties of the epoxy resin, while improving the reaction speed and final curing degree of the resin, reducing the use of catalysts and reducing production costs.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0007] A polyurethane-modified epoxy resin, the resin comprising the following components: NCO-terminated polyurethane; an amine curing agent; an epoxy resin; wherein the NCO-terminated polyurethane has the following structure:

[0008]

[0009] One or more of , wherein n is an integer greater than or equal to 1.

[0010] In the present invention, due to the special structure of the dihydric phenol or alcohol and the isocyanate selected corresponding to the amine, the -NCO-terminated polyurethane has a structure completely similar to that of the epoxy resin, making it completely compatible with the epoxy resin, and can improve its toughness and impact resistance without losing the strength of the epoxy resin itself. At the same time, the NCO-terminated polyurethane preferentially reacts with the amine curing agent to release a large amount of heat, further promoting the reaction of the amine curing agent and the epoxy resin, and can achieve segmented reaction, segmented heat release and final complete curing without adding a catalyst, thereby obtaining a polymer material with excellent performance.

[0011] In one embodiment of the present invention, the NCO-terminated polyurethane is prepared by reacting a dihydric phenol and / or alcohol with an isocyanate having an NCO functional group ≥ 2; preferably, the dihydric phenol and / or alcohol contains 2,2-diphenylpropane in its structure, preferably

[0012]

[0013] One or more; preferably, the isocyanate is selected from aromatic and / or aliphatic isocyanates, preferably one or more of 4,4'-diisocyanate diphenylmethane MDI, 4,4'-diisocyanate dicyclohexylmethane HMDI, toluene diisocyanate TDI, and isophorone diisocyanate IPDI; preferably, the molar ratio of the NCO group of the isocyanate to the OH group of the diphenol and / or alcohol is (1.2-2):1.

[0014] In one embodiment of the present invention, the amine curing agent is selected from diprimary amines, and preferably the residue structure of the diprimary amine after removing the amino functional group is the same as the residue structure of the isocyanate after removing the NCO functional group.

[0015] In one embodiment of the present invention, the epoxy resin is selected from bisphenol A epoxy resin, preferably one or more of E44, E51, and E54.

[0016] In one embodiment of the present invention, -NH2 in the amine curing agent reacts with -NCO in the NCO-terminated polyurethane, The molar ratio is 1:(0.1-0.3):(0.9-0.7).

[0017] Another object of the present invention is to provide a method for preparing polyurethane-modified epoxy resin.

[0018] A method for preparing the above-mentioned polyurethane-modified epoxy resin comprises the following steps: reacting dihydric phenol and / or alcohol with isocyanate having NCO functional group ≥ 2, and then mixing with epoxy resin to prepare component A, and an amine curing agent as component B.

[0019] In one embodiment of the present invention, the reaction temperature is 60-120° C., and the reaction time is 2-3 hours.

[0020] Another object of the present invention is to provide a use of polyurethane modified epoxy resin.

[0021] A use of a polyurethane modified epoxy resin, wherein the resin is the above resin, or is a resin prepared by the above method, and the polyurethane modified epoxy resin is used for composite materials.

[0022] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0023] The -NCO-terminated polyurethane used for modification has a similar structure to the epoxy resin and good compatibility, and can improve its toughness and impact resistance without losing the strength of the epoxy resin itself. DETAILED DESCRIPTION

[0024] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0025] The isocyanates and amine curing agents with at least two NCO functional groups in the following examples and comparative examples are all products sold by Wanhua Chemical, with the content of the main component being greater than or equal to 97%. Other raw materials are purchased through commercial channels and are chemically pure.

[0026] The main test methods of the present invention are as follows:

[0027] Glass transition temperature: DSC test, Discovery DSC2500 / 250 / 25, temperature range 25-200°C, heating rate 10°C / min, two scans.

[0028] Impact strength: GB / T 1843-2008 Determination of cantilever beam impact strength of plastics;

[0029] Tensile strength, elongation at break: GB / T1040.1-2006 Determination of tensile properties of plastics, tensile rate is 5mm / min.

[0030] Example 1

[0031] 1 mol of bisphenol A and 1.2 mol of HMDI were added into a reaction kettle, nitrogen was introduced, the temperature was raised to 60°C, stirred for 3 hours, cooled and discharged to obtain -NCO terminated polyurethane, which was evenly mixed with 3.6 mol of E51 to obtain component A.

[0032] HMDA was used as the B component.

[0033] 2 mol of component B and the above component A were mixed and stirred evenly, degassed at a centrifuge speed of 5000 r / min for 3 min, poured into a PTFE mold, cured at 80°C for 2 h, and taken out for performance testing.

[0034] Example 2

[0035] 1 mol of bisphenol A bis(2-hydroxypropyl) ether and 2 mol of IPDI were added into a reaction kettle, nitrogen was introduced, the temperature was raised to 100°C, stirred for 2.5 hours, cooled and discharged to obtain -NCO terminated polyurethane, which was evenly mixed with 4.7 mol of E51 to obtain component A.

[0036] IPDA was used as the B component.

[0037] 3.35 mol of component B and the above component A were mixed and stirred evenly, degassed at a centrifuge speed of 5000 r / min for 3 min, poured into a PTFE mold, cured at 80° C. for 2 h, and taken out for performance testing.

[0038] Example 3

[0039] 1 mol of bisphenol A bis(hydroxypropyl) ether and 1.5 mol of MDI were added into a reaction kettle, nitrogen was introduced, the temperature was raised to 120°C, stirred for 2 hours, cooled and discharged to obtain -NCO terminated polyurethane, which was evenly mixed with 4 mol of E44 to obtain component A.

[0040] MDA was used as the B component.

[0041] 2.5 mol of component B and the above component A were mixed and stirred evenly, degassed at a centrifuge speed of 5000 r / min for 3 min, poured into a PTFE mold, cured at 80° C. for 2 h, and taken out for performance testing.

[0042] Example 4

[0043] 1 mol of bisphenol A and 1.2 mol of HMDI were added into a reaction kettle, nitrogen was introduced, the temperature was raised to 80°C, stirred for 3 hours, cooled and discharged to obtain -NCO terminated polyurethane, which was evenly mixed with 3.6 mol of E51 to obtain component A.

[0044] IPDA was used as the B component.

[0045] 2 mol of component B and the above component A were mixed and stirred evenly, degassed at a centrifuge speed of 5000 r / min for 3 minutes, then poured into a polytetrafluoroethylene mold, cured at 100°C for 2.5 hours, and taken out for performance testing.

[0046] Comparative Example 1

[0047] Compared with Example 1, the difference is that component A of this comparative example is E51 resin, which does not contain -NCO-terminated polyurethane.

[0048] 1 mol HMDA and 2 mol of the above component A were mixed evenly, degassed at a centrifuge speed of 5000 r / min for 3 min, poured into a PTFE mold, cured at 80°C for 2 h, and taken out for performance testing.

[0049] Comparative Example 2

[0050] Compared with Example 3, the difference is that the -NCO terminated polyurethane is prepared from common diols, and no diprimary amine whose residue structure after removing the functional groups is the same as the isocyanate residue structure is used.

[0051] 1 mol of ethylene glycol and 1.5 mol of MDI were added into the reactor, nitrogen was introduced, the temperature was raised to 120°C, stirred for 2 hours, cooled and discharged to obtain -NCO terminated polyurethane, which was evenly mixed with 4 mol of E44 to obtain component A.

[0052] MDA was used as the B component.

[0053] 2.5 mol of component B and the above component A were mixed and stirred evenly, degassed at a centrifuge speed of 5000 r / min for 3 min, poured into a PTFE mold, cured at 80°C for 2 h, and taken out for performance testing.

[0054] The test results are shown in the table below:

[0055]

[0056] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A polyurethane modified epoxy resin, characterized in that: The resin comprises the following components: NCO terminated polyurethane; Amine curing agent; Epoxy resin; Among them, NCO-terminated polyurethane has the following structure: One or more of , wherein n is an integer greater than or equal to 1.

2. The resin according to claim 1, characterized in that NCO-terminated polyurethanes are prepared by reacting dihydric phenols and / or alcohols with isocyanates having an NCO functional group ≥ 2; Preferably, the dihydric phenol and / or alcohol contains 2,2-diphenylpropane in its structure, preferably One or more of; Preferably, the isocyanate is selected from aromatic and / or aliphatic isocyanates, preferably one or more of 4,4'-diisocyanate diphenylmethane MDI, 4,4'-diisocyanate dicyclohexylmethane HMDI, toluene diisocyanate TDI, and isophorone diisocyanate IPDI; Preferably, the molar ratio of the NCO groups of the isocyanate to the OH groups of the dihydric phenol and / or alcohol is (1.2-2):

1.

3. The resin according to claim 1 or 2, characterized in that The amine curing agent is selected from diprimary amines, and preferably the residue structure after the amino functional group is removed from the diprimary amine is the same as the residue structure after the NCO functional group is removed from the isocyanate.

4. The resin according to any one of claims 1 to 3, characterized in that The epoxy resin is selected from bisphenol A epoxy resin, preferably one or more of E44, E51, and E54.

5. The resin according to any one of claims 1 to 4, characterized in that -NH2 in amine curing agents and -NCO in NCO-terminated polyurethanes and epoxy resins The molar ratio is 1:(0.1-0.3): (0.9-0.7)。 6. A method for preparing the polyurethane-modified epoxy resin according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: reacting dihydric phenol and / or alcohol with isocyanate having NCO functional group ≥ 2, and then mixing with epoxy resin to prepare component A, and using amine curing agent as component B.

7. The method according to claim 6, characterized in that The reaction temperature is 60-120° C., and the reaction time is 2-3 hours.

8. Use of a polyurethane-modified epoxy resin, wherein the resin is the resin according to any one of claims 1 to 5, or is a resin prepared by the method according to claim 6 or 7, and the polyurethane-modified epoxy resin is used for composite materials.

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