Air-drying styrene-free vinyl ester resin and preparation method thereof

Abstract

The invention relates to the technical field of polymer composite materials, in particular to air-drying styrene-free vinyl ester resin and a preparation method thereof. Comprising the following steps: S1, adding epoxy resin, methacrylic acid and a polymerization inhibitor into a reaction kettle, stirring, raising the temperature for the first time, adding a catalyst in batches, raising the temperature for the second time after adding, keeping the temperature, and continuing the reaction until the reaction is finished; s2, adding binary anhydride, and carrying out heat-preservation reaction until the reaction is finished; s3, adding allyl ether until the reaction is finished; and S4, adding the reactant into the acrylate monomer, continuously stirring until the mixture is uniformly mixed, and finally cooling to 35 DEG C or below to obtain the product. According to the invention, dicarboxylic anhydride reacts with hydroxyl on a vinyl resin chain under a low temperature condition to introduce carboxyl, and an air-drying group allyl ether is introduced under a mild condition, so that the air-drying property of the resin is improved, reactants are prevented from gelling due to high temperature, the reaction process is simple and easy to control, and the preparation method is suitable for industrial production. The air-drying styrene-free vinyl resin with good comprehensive performance is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of polymer composite materials, in particular to an air-drying styrene-free vinyl ester resin and a preparation method thereof. Background Art

[0002] Vinyl ester resin is usually made by the ring-opening addition chemical reaction of epoxy resin and unsaturated monocarboxylic acid and diluted with styrene. Its process performance is similar to that of unsaturated polyester resin, and its chemical structure is similar to that of epoxy resin, so it has excellent chemical resistance and solvent resistance. It combines the advantages of unsaturated polyester resin and epoxy resin and is an excellent corrosion-resistant resin. However, with people's increasing attention to environmental safety and the increasingly stringent national policies on the resin industry, the development of low-styrene or styrene-free vinyl resins has become a hot topic of research and development at home and abroad. At present, there are literature reports on styrene-free vinyl ester resin technology, which usually uses low-odor, high-flash point, and high-boiling point acrylic monomers instead of styrene, which has a relatively high cost-effectiveness.

[0003] However, both styrene-free vinyl resin and ordinary vinyl ester resin have a defect, that is, the surface layer in contact with air during resin curing is easy to become sticky, which makes construction more difficult and affects the further use of the resin. The commonly used solutions are: 1) Add a film-forming material (such as paraffin) to form a mechanical shield against the air, which can be dissolved in the resin and diffused to the surface after construction. However, paraffin is difficult to dissolve in acrylic monomers, so this method is not suitable for styrene-free vinyl resin. 2) Modify the resin with polyol allyl ether and cellulose acetate butyrate, but the half-esterification method and end-capping method are not suitable for use in the synthesis of vinyl resin. The initial method modification puts allyl ether and other diols and dibasic acids into the reactor at the same time, and performs esterification reaction at 185°C, but a large amount of inhibitor must be added during the esterification process to prevent the material from gelling in the reactor, which complicates the resin production. Therefore, the air-drying problem of styrene-free vinyl resin has become a difficult problem to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide an air-drying styrene-free vinyl ester resin and a preparation method thereof.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing an air-drying styrene-free vinyl ester resin, the preparation method comprising the following steps:

[0007] S1: adding epoxy resin, methacrylic acid and polymerization inhibitor into a reaction kettle, stirring, heating for the first time, adding catalyst in batches, adding materials each time after the end of heat release, heating for the second time after the addition is completed and keeping the temperature to continue the reaction, testing the acid value intermittently during the reaction, and reacting until the acid value AV is less than 10mgKOH / g;

[0008] S2 adds dibasic acid anhydride, keeps warm for a period of time and then tests the acid value, and reacts until the difference between the two acid values ​​△AV≤5mgKOH / g;

[0009] S3: Add allyl ether, test the acid value intermittently, and react until the acid value AV is less than 10 mgKOH / g;

[0010] S4: adding the reactants to the acrylic ester monomers, stirring continuously until the mixture is uniform, and finally cooling to below 35° C. to obtain an air-drying styrene-free vinyl ester resin.

[0011] Furthermore, the polymerization inhibitor in step S1 is selected from one of hydroquinone HQ, methyl hydroquinone THQ and p-benzoquinone PBQ.

[0012] Furthermore, in step S1, the temperature is raised to 90° C. for the first time and to 110-120° C. for the second time, and the time interval for testing the acid value is once every 1 hour.

[0013] Furthermore, the allyl ether in step S3 is allyl glycidyl ether.

[0014] Furthermore, the molar ratio of the dibasic acid anhydride in step S2 to the allyl glycidyl ether in step S3 is (1.0-1.05):1.

[0015] Furthermore, the dibasic acid anhydride in step S2 is selected from maleic anhydride, phthalic anhydride, and tetrahydrophthalic anhydride.

[0016] Furthermore, the temperature of the heat preservation reaction in step S2 is 90-120° C., the heat preservation reaction time is 30 minutes, and the time interval for testing the acid value in step S3 is to perform an acid value test once every 1 hour.

[0017] Furthermore, the catalyst in step S1 is selected from benzyltriethylammonium chloride and triphenylphosphine.

[0018] Furthermore, in step S4, the acrylic acid ester monomer includes one or two of hydroxyethyl methacrylate, 1,6-hexanediol diacrylate, and 1,4-butanediol diacrylate.

[0019] An air-drying styrene-free vinyl ester resin, which has the following composition by weight:

[0020]

[0021] The beneficial effects of the technical solution of the present invention are:

[0022] In the present invention, carboxyl groups are introduced by reacting dibasic acid anhydride with hydroxyl groups on vinyl resin chains under low temperature conditions, and air-drying group allyl ether is introduced under mild conditions, thereby improving the air-drying property of the resin, avoiding gelation of reactants due to high temperature, making the reaction process simple and easy to control, and obtaining an air-drying styrene-free vinyl resin with good comprehensive performance. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with specific implementation methods and description.

[0024] Example 1

[0025] A method for preparing an air-drying styrene-free vinyl ester resin, comprising the following weight ratios:

[0026]

[0027] The following steps are involved:

[0028] a) Add epoxy resin, methacrylic acid and polymerization inhibitor into a reactor, stir, heat the reactor to 90°C, add catalyst in batches, wait until the exotherm ends before adding, raise the temperature to 120°C and keep the reaction, test the acid value every 1 hour, and react until the acid value AV is less than 10mgKOH / g.

[0029] b) Add MA, keep the temperature at 120℃ for 30 minutes, then test the acid value, and react until the difference between the two acid values ​​△AV≤5mgKOH / g.

[0030] c) Add allyl glycidyl ether, test the acid value every 1 hour, and react until the acid value AV is less than 10 mgKOH / g.

[0031] d) adding the reactants to hydroxyethyl methacrylate, stirring continuously until the mixture is uniformly mixed, and finally cooling the mixture to below 35° C. to obtain an air-drying styrene-free vinyl ester resin.

[0032] Example 2

[0033] A method for preparing an air-drying styrene-free vinyl ester resin, comprising the following weight ratios:

[0034]

[0035] The following steps are involved:

[0036] a) Add epoxy resin, methacrylic acid and polymerization inhibitor into a reactor, stir, heat the reactor to 90°C, add catalyst in batches, wait until the exotherm ends before adding, raise the temperature to 110°C and keep the reaction, test the acid value every 1 hour, and react until the acid value AV is less than 10mgKOH / g.

[0037] b) Add MA, keep the temperature at 110℃ for 30 minutes, then test the acid value. React until the difference between the two acid values ​​△AV≤5mgKOH / g.

[0038] c) Add allyl glycidyl ether, test the acid value every 1 hour, and react until the acid value AV is less than 10 mgKOH / g.

[0039] d) adding the reactants to the acrylic ester monomer, stirring continuously until the mixture is uniformly mixed, and finally cooling the mixture to below 35° C. to obtain an air-drying styrene-free vinyl ester resin.

[0040] Example 3

[0041] A method for preparing an air-drying styrene-free vinyl ester resin, comprising the following weight ratios:

[0042]

[0043] The following steps are involved:

[0044] a) Add epoxy resin, methacrylic acid and polymerization inhibitor into a reactor, stir, heat the reactor to 90°C, add catalyst in batches, wait until the exotherm ends before adding, raise the temperature to 110°C and keep the reaction, test the acid value every 1 hour, and react until the acid value AV is less than 10mgKOH / g.

[0045] b) Add tetrahydrophthalic anhydride, keep the temperature at 90°C for 30 minutes, then test the acid value, and react until the difference between the two acid values ​​△AV ≤ 5 mgKOH / g.

[0046] c) Add allyl glycidyl ether, test the acid value every 1 hour, and react until the acid value AV is less than 10 mgKOH / g.

[0047] d) adding the reactants to hydroxyethyl methacrylate, stirring continuously until the mixture is uniformly mixed, and finally cooling the mixture to below 35° C. to obtain an air-drying styrene-free vinyl ester resin.

[0048] Comparative Example 1

[0049] The preparation method of the styrene-free vinyl ester resin in this comparative example is substantially the same as that in Example 1, except that the air-drying group allyl ether is not introduced in this comparative example.

[0050] The styrene-free vinyl ester resin of this comparative example is made from the following weight ratio:

[0051]

[0052]

[0053] The preparation method of the styrene-free vinyl ester resin of this comparative example comprises the following steps:

[0054] a) Add methacrylic acid, catalyst and polymerization inhibitor into a reaction kettle, ventilate and stir, raise the temperature to 110-120°C, add epoxy resin three times, wait for the end of heat release each time before adding, test the acid value every 1 hour after the addition is completed, and react until the acid value AV is less than 10mgKOH / g.

[0055] b) adding the reactants to the acrylic ester monomers, stirring continuously until the mixture is uniformly mixed, and finally cooling the mixture to below 35° C. to obtain a styrene-free vinyl ester resin.

[0056] Some properties of the styrene-free unsaturated polyester resins prepared in Examples 1 to 3 and Comparative Example 1 are shown in the following table:

[0057] Test items Test Standards Example 1 Example 2 Example 3 Comparative Example 1 Brookfield Viscosity ISO2555 540 488 460 499 Solid GB / T7193 55 60 58 60 Tensile strength / Mpa GB / T2567 83 70 77 90 Tensile modulus / Mpa GB / T2567 3900 3300 3900 3900 Elongation at break / % GB / T2567 3.1 2.7 2.9 3.5 Bending strength / Mpa GB / T2567 135 110 138 150 Flexural modulus / Mpa GB / T2567 3700 3300 3700 3800 Barcol hardness GB / T3854 50 45 48 55 HDT / ℃ GB / T1634 103 108 110 115 Dry time --- 5 8 6 ＞48h Working time --- 8 12 9 ＞3d

[0058] In addition, it should be understood that although this specification is described according to implementation methods, not every implementation method contains only one independent claim scheme. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing an air-drying styrene-free vinyl ester resin, characterized in that: The preparation method comprises the following steps: S1: adding epoxy resin, methacrylic acid and polymerization inhibitor into a reaction kettle, stirring, heating for the first time, adding catalyst in batches, adding materials each time after the end of heat release, heating for the second time after the addition is completed and keeping the temperature to continue the reaction, testing the acid value intermittently during the reaction, and reacting until the acid value AV is less than 10mgKOH / g; S2: Add dibasic acid anhydride, keep warm for a period of time, then test the acid value, and react until the difference between two acid values ​​△AV ≤5mgKOH / g; S3: Add allyl ether, test the acid value intermittently, and react until the acid value AV is less than 10 mgKOH / g; S4: adding the reactants to the acrylic ester monomers, stirring continuously until the mixture is uniformly mixed, and finally cooling to below 35° C. to obtain an air-drying styrene-free vinyl ester resin.

2. The method for preparing an air-drying styrene-free vinyl ester resin according to claim 1, characterized in that: The polymerization inhibitor in step S1 is selected from one of hydroquinone HQ, methyl hydroquinone THQ and p-benzoquinone PBQ.

3. The method for preparing an air-drying styrene-free vinyl ester resin according to claim 1, characterized in that: In the step S1, the temperature is raised to 90° C. for the first time and to 110-120° C. for the second time, and the time interval for testing the acid value is once every 1 hour.

4. The method for preparing an air-drying styrene-free vinyl ester resin according to claim 1, characterized in that: The allyl ether in step S3 is allyl glycidyl ether.

5. The method for preparing an air-drying styrene-free vinyl ester resin according to claim 1, characterized in that: The molar ratio of the dibasic acid anhydride in step S2 to the allyl glycidyl ether in step S3 is (1.0-1.05):

1.

6. The method for preparing an air-drying styrene-free vinyl ester resin according to claim 1, characterized in that: The dibasic acid anhydride in step S2 is selected from maleic anhydride, phthalic anhydride, and tetrahydrophthalic anhydride.

7. The method for preparing an air-drying styrene-free vinyl ester resin according to claim 1, characterized in that: The temperature of the heat preservation reaction in step S2 is 90-120° C., the time of the heat preservation reaction is 30 minutes, and the time interval for testing the acid value in step S3 is to perform an acid value test once every 1 hour.

8. The method for preparing an air-drying styrene-free vinyl ester resin according to claim 1, characterized in that: The catalyst in step S1 is selected from benzyltriethylammonium chloride and triphenylphosphine.

9. The method for preparing an air-drying styrene-free vinyl ester resin according to claim 1, characterized in that: In the step S4, the acrylic acid ester monomer includes one or two of hydroxyethyl methacrylate, 1,6-hexanediol diacrylate, and 1,4-butanediol diacrylate.

10. The air-drying styrene-free vinyl ester resin prepared by the method according to any one of claims 1 to 9, characterized in that: The mass parts of the air-drying styrene-free vinyl ester resin are as follows: Epoxy resin 27-34wt%, Methacrylic acid 13-16 wt%, Dibasic acid anhydride 4-8wt%, Allyl ether 5-8wt%, Acrylate monomer 40-45 wt%, Inhibitor 0.05-0.1wt‰, Catalyst 4-5wt‰.

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