Flame-retardant unsaturated polyester resin and preparation method thereof

Abstract

The invention provides flame-retardant unsaturated polyester resin and a preparation method thereof.The flame-retardant unsaturated polyester resin is obtained by sequentially adding diol, maleic anhydride, a DOPO modified dicarboxylic acid comonomer and an auxiliary into a reaction kettle and reacting in an inert environment for a preset time, and the flame-retardant unsaturated polyester resin can be obtained by adding the DOPO modified dicarboxylic acid comonomer, so that the flame-retardant unsaturated polyester resin is obtained. A DOPO flame-retardant unit can be embedded into unsaturated polyester resin in a chain extension reaction process, compared with filler type flame-retardant unsaturated polyester resin, the stability and the curing performance of a resin matrix are remarkably improved, the DOPO flame-retardant unit is embedded into the resin matrix in a chemical bond form, the conditions of migration and agglomeration of a flame retardant can be completely avoided, and the flame-retardant performance of the flame-retardant unsaturated polyester resin is improved. The flame-retardant unsaturated polyester has the advantages that the service life of the flame-retardant unsaturated polyester can be effectively prolonged, the performance of the resin cannot be reduced along with time in the actual use process, the implementation cost is low, the stability of a resin product is remarkably improved, the use experience is improved, and popularization and implementation are convenient.

Description

Technical Field

[0001] The present application belongs to the technical field of chemical raw material production, and specifically relates to a flame retardant unsaturated polyester resin and a preparation method thereof. Background Art

[0002] In the prior art, the flame retardant components in the flame retardant unsaturated polyester are mostly physically mixed with the base in the form of fillers, that is, by adding specific inorganic or organic fillers to the unsaturated polyester resin base to improve the flame retardant properties of the unsaturated polyester resin itself.

[0003] In the prior art, in the existing filler-type flame-retardant unsaturated polyester resin, the flame-retardant component is mostly mixed with the base resin in the form of filler. During long-term use, filler migration and agglomeration will occur, which will cause the flame-retardant component to fail and significantly reduce the flame retardant properties of the resin. Although the use of coupling fillers can solve the problem of filler migration or agglomeration to a certain extent, in the actual mass production process, on the one hand, it will lead to a substantial increase in production costs. On the other hand, if small molecule organic flame retardants are directly used, there will be a problem of filler escape during the production process, which will cause the flame retardancy, mechanical properties and curing properties to deteriorate over time. Therefore, improvements are urgently needed. Summary of the invention

[0004] In order to solve the problem that in the prior art, the flame retardant components in the flame retardant unsaturated polyester are mostly physically mixed with the base in the form of fillers, and in the long-term actual use process, filler migration and agglomeration will occur, which will cause the flame retardant component to fail and significantly reduce the flame retardant performance of the resin. Although replacing the halogen flame retardant with a coupled flame retardant can solve the problems of filler migration and agglomeration, it will significantly increase the production cost. A flame retardant unsaturated polyester resin is proposed;

[0005] In order to solve the technical problem raised in the present application, the present application also provides a method for preparing a flame retardant unsaturated polyester resin.

[0006] The present application adopts the following scheme, a method for preparing a flame-retardant unsaturated polyester resin, comprising the following steps: adding diol, maleic anhydride, DOPO-modified dicarboxylic acid comonomer and additives into a reactor in sequence, reacting for 15h-20h under an inert environment and cooling to obtain the flame-retardant unsaturated polyester resin.

[0007] In one embodiment, a method for preparing a flame retardant unsaturated polyester resin comprises the following steps:

[0008] Step 101. Add diol, maleic anhydride, and DOPO-modified dicarboxylic acid comonomer into a reaction kettle in a mass ratio of (3.3-5): (2.5-4.5): 1, react for 15h-20h under N2 atmosphere at 150°C-220°C, and cool to obtain a high-purity flame-retardant unsaturated polyester resin;

[0009] Step 102. The high-purity flame-retardant unsaturated polyester resin prepared in step 101 is conveyed to a dilution kettle, and the high-purity flame-retardant unsaturated polyester resin is diluted with styrene to a preset concentration, and then filtered, tested and packaged in sequence to obtain a finished flame-retardant unsaturated polyester resin.

[0010] In the actual implementation process, the reaction equation of step 101 is as follows:

[0011]

[0012] In one embodiment, in step 101, during the reaction, samples are taken from the reactor every 30 minutes and the acid value of the samples is detected. When the acid value of the samples is ≤50 mg / L·KOH, the reaction is terminated.

[0013] In one embodiment, the structural formula of the high-purity flame-retardant unsaturated polyester resin prepared in step 101 is as follows:

[0014]

[0015] The value range of n is 310-1250.

[0016] In one embodiment, the method for preparing the DOPO-modified dicarboxylic acid comonomer in step 101 comprises the following steps:

[0017] Step 201. Dissolve glycine, terephthalaldehyde and acetic acid in tetrahydrofuran in sequence to obtain solution A, transfer solution A to a condensation reflux device, heat and reflux for 2h-6h, cool and drop ammonia water therein, adjust the pH value to 8-9, and obtain intermediate B;

[0018] Step 202. Add DOPO to the intermediate B prepared in step 201 to obtain solution C, transfer solution C to a condensation reflux device, heat and reflux for 2h-8h, evaporate the organic solvent, wash with water, and dry to obtain a DOPO-modified dicarboxyl copolymer monomer.

[0019] In the actual implementation process, the reaction equation of step 201 is as follows:

[0020]

[0021] In actual implementation, the reaction equation of step 202 is as follows:

[0022]

[0023] In one embodiment, in step 201, the molar ratio of glycine, terephthalaldehyde and acetic acid solution is 2:1:0.1, and in step 202, the molar ratio of DOPO to glycine is (1.05-1.1):1.

[0024] In one embodiment, in step 202, during the heating reflux process, the progress of the reaction is monitored by HPLC, and when the DOPO peak is close to disappearing, the reaction is terminated.

[0025] In one embodiment, in step 201, the structural formula of intermediate B is:

[0026]

[0027] In one embodiment, in step 202, the structural formula of the DOPO-modified dicarboxyl comonomer is:

[0028]

[0029] During the actual implementation process, when the flame-retardant unsaturated polyester provided by the present application is burned, the DOPO embedded in the resin matrix will first decompose and promote the polymer to form a carbon layer. Secondly, the hypophosphorous acid therein will be oxidized into phosphoric acid and its polymer, which will cover the polymer material to isolate oxygen. In this process, the hypophosphorous acid will also release PO· free radicals, which will capture the free radicals generated by the burning resin matrix and delay the combustion chain reaction. Finally, the high-temperature decomposition of DOPO produces non-flammable gas, which will dilute the concentration of combustible gas and significantly delay the spread of flame.

[0030] The novel flame-retardant unsaturated polyester resin prepared in the present application firmly connects the flame-retardant component DOPO to the chain segment through a stable carbon-phosphorus single bond, which can effectively solve the defects of poor stability and curing of filler-type flame-retardant unsaturated polyester resin. In addition, the synthesis process of this scheme is simple and the cost is low, which is suitable for industrial promotion and use.

[0031] In order to solve the technical problem raised in the present application, the present application also provides a flame retardant unsaturated polyester resin, which is prepared by the above-mentioned preparation method of the unsaturated polyester resin.

[0032] Compared with the prior art, this application has the following beneficial effects:

[0033] The present application provides a flame-retardant unsaturated polyester resin and a preparation method thereof. The flame-retardant unsaturated polyester resin is obtained by sequentially adding diol, maleic anhydride, DOPO-modified dicarboxylic acid comonomer and an auxiliary agent into a reactor, and reacting for a predetermined time under an inert environment. The DOPO-modified dicarboxylic acid comonomer is added to embed the DOPO flame-retardant unit into the unsaturated polyester resin during the chain extension reaction. Compared with the filler-type flame-retardant unsaturated polyester resin, the stability and curing performance of the resin matrix are significantly improved. The DOPO flame-retardant unit is embedded in the resin matrix in the form of a chemical bond, which can completely avoid the migration and agglomeration of the flame retardant, and can effectively extend the service life of the flame-retardant unsaturated polyester. In actual use, the performance of the resin will not decrease with the passage of time. The invention has the advantages of low implementation cost, significantly improved stability of the resin product, improved use experience, and easy promotion and implementation. DETAILED DESCRIPTION

[0034] The present technical solution is further illustrated in combination with Examples 1-3 and Comparative Example 1.

[0035] Example 1

[0036] (1) The method for preparing the DOPO-modified dicarboxylic acid comonomer comprises the following steps:

[0037] Step 201. Glycine, terephthalaldehyde and acetic acid are dissolved in tetrahydrofuran in a molar ratio of 2:1:0.1 to obtain solution A, and solution A is transferred to a condensation reflux device, heated to reflux for 2.5 hours, cooled and ammonia water is added dropwise thereto, and the pH value is adjusted to 8 to obtain intermediate B;

[0038] Step 202. Add DOPO to the intermediate B prepared in step 201 to obtain solution C, in which the molar ratio of DOPO to glycine is 1.05:1. Transfer solution C to a condensing reflux device and heat to reflux for 3.5 hours. During the heating and reflux process, monitor the progress of the reaction by HPLC. When the DOPO peak is close to disappearing, the reaction is terminated. After evaporating the organic solvent, washing with water, and drying, the DOPO-modified dicarboxyl copolymer monomer is obtained.

[0039] (2) A method for preparing a flame retardant unsaturated polyester resin, comprising the following steps:

[0040] Step 101. Add diol, maleic anhydride, and DOPO-modified dicarboxylic acid comonomer into a reactor in a mass ratio of 3.5:3:1, and react for 16.5 hours at 177° C. in a N2 atmosphere. During the reaction, take a sample from the reactor every 30 minutes and detect the acid value of the sample. When the acid value of the sample is ≤50 mg / L·KOH, the reaction is terminated, and the high-purity flame-retardant unsaturated polyester resin is obtained by cooling. The acid value of the high-purity flame-retardant unsaturated polyester resin is 49 mg / L·KOH.

[0041] Step 102. The high-purity flame-retardant unsaturated polyester resin prepared in step 101 is conveyed to a dilution kettle, and the high-purity flame-retardant unsaturated polyester resin is diluted with styrene to a preset concentration, and then filtered, tested and packaged in sequence to obtain a finished flame-retardant unsaturated polyester resin.

[0042] Example 2

[0043] (1) The method for preparing the DOPO-modified dicarboxylic acid comonomer comprises the following steps:

[0044] Step 201. Glycine, terephthalaldehyde and acetic acid are dissolved in tetrahydrofuran in a molar ratio of 2:1:0.1 to obtain solution A, and solution A is transferred to a condensation reflux device, heated to reflux for 4.5 hours, cooled and ammonia water is added dropwise thereto, and the pH value is adjusted to 9 to obtain intermediate B;

[0045] Step 202. Add DOPO to the intermediate B prepared in step 201 to obtain solution C. In solution C, the molar ratio of DOPO to glycine is 1.07:1. Transfer solution C to a condensing reflux device and heat to reflux for 4.5 hours. During the heating and reflux process, monitor the progress of the reaction by HPLC. When the DOPO peak is close to disappearing, the reaction is terminated. After evaporating the organic solvent, washing with water, and drying, the DOPO-modified dicarboxyl copolymer monomer is obtained.

[0046] (2) A method for preparing a flame retardant unsaturated polyester resin, comprising the following steps:

[0047] Step 101. Add diol, maleic anhydride, and DOPO-modified dicarboxylic acid comonomer into a reactor in a mass ratio of 4.1:3.8:1, and react for 18.5 hours at 188° C. in a N2 atmosphere. During the reaction, take a sample from the reactor every 30 minutes and detect the acid value of the sample. When the acid value of the sample is ≤50 mg / L·KOH, the reaction is terminated, and the temperature is lowered to obtain a high-purity flame-retardant unsaturated polyester resin. The acid value of the high-purity flame-retardant unsaturated polyester resin is 49.2 mg / L·KOH.

[0048] Step 102. The high-purity flame-retardant unsaturated polyester resin prepared in step 101 is conveyed to a dilution kettle, and the high-purity flame-retardant unsaturated polyester resin is diluted with styrene to a preset concentration, and then filtered, tested and packaged in sequence to obtain a finished flame-retardant unsaturated polyester resin.

[0049] Example 3

[0050] (1) The method for preparing the DOPO-modified dicarboxylic acid comonomer comprises the following steps:

[0051] Step 201. Dissolve glycine, terephthalaldehyde and acetic acid in tetrahydrofuran in a molar ratio of 2:1:0.1 to obtain solution A, transfer solution A to a condensation reflux device, heat and reflux for 6 hours, cool and drop ammonia water therein, adjust the pH value to 9, and obtain intermediate B;

[0052] Step 202. Add DOPO to the intermediate B prepared in step 201 to obtain solution C, in which the molar ratio of DOPO to glycine is 1.1:1. Transfer solution C to a condensing reflux device and heat to reflux for 8 hours. During the heating and reflux process, monitor the progress of the reaction by HPLC. When the DOPO peak is close to disappearing, the reaction is terminated. After evaporating the organic solvent, washing with water, and drying, the DOPO-modified dicarboxyl copolymer monomer is obtained.

[0053] (2) A method for preparing a flame retardant unsaturated polyester resin, comprising the following steps:

[0054] Step 101. Add diol, maleic anhydride, and DOPO-modified dicarboxylic acid comonomer into a reactor in a mass ratio of 5:4.5:1, and react for 19.5 hours under a N2 atmosphere at 210°C. During the reaction, take a sample from the reactor every 30 minutes and detect the acid value of the sample. When the acid value of the sample is ≤50 mg / L·KOH, the reaction is terminated, and the temperature is lowered to obtain a high-purity flame-retardant unsaturated polyester resin. The acid value of the high-purity flame-retardant unsaturated polyester resin is 49.5 mg / L·KOH.

[0055] Step 102. The high-purity flame-retardant unsaturated polyester resin prepared in step 101 is conveyed to a dilution kettle, and the high-purity flame-retardant unsaturated polyester resin is diluted with styrene to a preset concentration, and then filtered, tested and packaged in sequence to obtain a finished flame-retardant unsaturated polyester resin.

[0056] Comparative Example 1

[0057] The common filler-type flame-retardant unsaturated polyester resin available on the market has a supply grade of ZRT907, and the content of halogen flame retardant therein is 3%-8% by weight.

[0058] The flame-retardant unsaturated polyester resins prepared in Examples 1-3 and Comparative Example 1 were first subjected to a resin casting performance test according to the standard of GB / T 2567, and then to a resin service life test;

[0059] The resin service life test method is as follows: 50g of samples are taken from Examples 1-3 and Comparative Example 1 respectively, and the corresponding samples are left to stand in a natural state for 24h, 48h, and 168h, and then the appearance, flame retardancy and curing properties of the resin are observed. The curing performance is measured by mixing the sample with toluene in a mass ratio of 1:1 to make a varnish, and the varnish is sprayed on a 30cm*30cm wood composite board with a spray gun. The curing performance of the resin is evaluated by the surface drying time of the varnish. The test results are shown in Table 1 below.

[0060] Table 1 Test results of Examples 1-3 and Comparative Example 1

[0061]

[0062] From the test results in Table 1, it can be seen that Comparative Example 1 is a common filler-type polyester resin available on the market. The flame retardant modifies the unsaturated polyester resin matrix in the form of physical dispersion. As the use time increases, the resin will show obvious stratification, the resin segment structure stability is low, and the filler in the resin system will migrate or agglomerate, thereby significantly reducing its own flame retardant properties and curing properties, and reducing the service life of the resin.

[0063] In Examples 1-3, the active hydrogen in the flame retardant component DOPO can be added to the C=N double bond generated by terephthalaldehyde and glycine, and the carboxyl group of glycine can replace part of the phthalic acid monomer to react with the polyol component, so that the flame retardant component can be embedded in the chain segment of the unsaturated polyester resin, thereby effectively solving the technical problems of poor stability and curing properties of the filler-type flame retardant unsaturated polyester resin.

[0064] During the actual implementation process, when the flame-retardant unsaturated polyester provided by the present application is burned, the DOPO embedded in the resin matrix will first decompose and promote the polymer to form a carbon layer. Secondly, the hypophosphorous acid therein will be oxidized into phosphoric acid and its polymer, which will cover the polymer material to isolate oxygen. In this process, the hypophosphorous acid will also release PO· free radicals, which will capture the free radicals generated by the burning resin matrix and delay the combustion chain reaction. Finally, the high-temperature decomposition of DOPO produces non-flammable gas, which will dilute the concentration of combustible gas and significantly delay the spread of flame.

[0065] The novel flame-retardant unsaturated polyester resin prepared in the present application firmly connects the flame-retardant component DOPO to the chain segment through a stable carbon-phosphorus single bond, which can effectively solve the defects of poor stability and curing of filler-type flame-retardant unsaturated polyester resin. In addition, the synthesis process of this scheme is simple and the cost is low, which is suitable for industrial promotion and use.

[0066] The above are only embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a flame retardant unsaturated polyester resin, characterized in that: The following steps are involved: The diol, maleic anhydride, DOPO-modified dicarboxylic acid comonomer and auxiliary agent are sequentially added into a reaction kettle, reacted for 15h-20h under an inert environment and cooled to obtain the flame-retardant unsaturated polyester resin.

2. The method for preparing a flame retardant unsaturated polyester resin according to claim 1, characterized in that: The following steps are involved: Step 101. Add diol, maleic anhydride, and DOPO-modified dicarboxylic acid comonomer into a reaction kettle in a mass ratio of (3.3-5): (2.5-4.5): 1, react for 15h-20h under N2 atmosphere at 150°C-220°C, and then cool to obtain a high-purity flame-retardant unsaturated polyester resin; Step 102. The high-purity flame-retardant unsaturated polyester resin prepared in step 101 is conveyed to a dilution kettle, and the high-purity flame-retardant unsaturated polyester resin is diluted with styrene to a preset concentration, and then filtered, tested and packaged in sequence to obtain a finished flame-retardant unsaturated polyester resin.

3. The method for preparing a flame retardant unsaturated polyester resin according to claim 2, characterized in that: In step 101, during the reaction process, samples are taken from the reactor every 30 minutes and the acid value of the samples is detected. When the acid value of the samples is ≤50 mg / L·KOH, the reaction is terminated.

4. The method for preparing a flame retardant unsaturated polyester resin according to claim 2, characterized in that: The structural formula of the high-purity flame-retardant unsaturated polyester resin prepared in step 101 is as follows: The value range of n is 310-1250.

5. The method for preparing a flame retardant unsaturated polyester resin according to claim 2, characterized in that: The method for preparing the DOPO-modified dicarboxylic acid comonomer in step 101 comprises the following steps: Step 201. Dissolve glycine, terephthalaldehyde and acetic acid in tetrahydrofuran in sequence to obtain solution A, transfer solution A to a condensation reflux device, heat and reflux for 2h-6h, cool and drop ammonia water therein, adjust the pH value to 8-9, and obtain intermediate B; Step 202. Add DOPO to the intermediate B prepared in step 201 to obtain solution C, transfer solution C to a condensation reflux device, heat and reflux for 2h-8h, evaporate the organic solvent, wash with water, and dry to obtain a DOPO-modified dicarboxyl copolymer monomer.

6. The method for preparing a flame retardant unsaturated polyester resin according to claim 5, characterized in that: In step 201, the molar ratio of glycine, terephthalaldehyde and acetic acid solution is 2:1:0.

1. In step 202, the molar ratio of DOPO to glycine is (1.05-1.1):

1.

7. The method for preparing a flame retardant unsaturated polyester resin according to claim 5, characterized in that: In step 202, during the heating and reflux process, the progress of the reaction is monitored by HPLC, and when the DOPO peak is close to disappearing, the reaction is terminated.

8. The method for preparing a flame retardant unsaturated polyester resin according to claim 5, characterized in that: In step 201, the structural formula of intermediate B is:

9. The method for preparing a flame retardant unsaturated polyester resin according to claim 5, characterized in that: In step 202, the structural formula of the DOPO-modified dicarboxyl comonomer is:

10. A flame retardant unsaturated polyester resin, characterized in that: The unsaturated polyester resin is prepared by the method for preparing the unsaturated polyester resin according to claims 1 to 9.

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