A fiber-reinforced vinyl ester resin composite material and its preparation method

Abstract

The present invention relates to the technical field of composite materials, and discloses a fiber-reinforced vinyl ester resin composite material and a preparation method thereof. This composite material uses vinyl ester resin as the main raw material and modified sepiolite fiber reinforcing additives as auxiliary materials, and is prepared by mixing. The modified sepiolite fiber reinforcing additive is sepiolite fiber surface-modified with a multi-polymeric phosphorus-containing flame retardant. The multi-polymeric phosphorus-containing flame retardant is equivalent to generating a "transition" structure between the sepiolite fiber and the vinyl ester resin, enabling the sepiolite fiber to efficiently exert its own enhancement and modification advantages, improving the load-bearing capacity of the composite material. Moreover, the structure of the multi-polymeric phosphorus-containing flame retardant contains a large number of triazine rings and phosphorus-containing flame retardant mechanisms, which can rapidly form an expanded carbon layer during the combustion of the composite material, isolating oxygen and heat, and preventing the combustion from continuing, thereby effectively improving the flame retardant performance of the composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and particularly relates to a fiber-reinforced vinyl ester resin composite material and a preparation method thereof. Background Art

[0002] Vinyl ester resin is a kind of resin prepared by the ring-opening esterification reaction of epoxy resin with methacrylic acid or acrylic acid. The two ends of its molecular structure contain vinyl groups, and the middle backbone is epoxy resin. Common raw materials include bisphenol A epoxy (MFE series) or phenolic epoxy (W series) reacting with methacrylic acid or acrylic acid. During the reaction, the epoxy groups of the epoxy resin react with unsaturated organic monocarboxylic acids (usually acrylic acid and methacrylic acid) to form unsaturated ester compounds with vinyl groups. The molecular main chain structure of vinyl ester resin determines its unique properties. The matrix of the molecular structure is the epoxy backbone, which enables it to inherit the advantages of epoxy resin, such as excellent chemical resistance, suitable for making various corrosion-resistant integral fiberglass products, corrosion-resistant fiberglass protective layers on the surfaces of metal structures and concrete structures, and various fiberglass pipes, storage tanks or equipment linings resistant to acids, alkalis, and salts.

[0003] However, in the continuous application process, it is found that the mechanical and mechanical strength of vinyl ester resin gradually fails to meet the requirements of some industries, and it is itself a flammable material, there are certain usage risks. Therefore, the modification of vinyl ester resin is of great significance for its further development and application. Among them, fiber reinforcement is one of the effective means to improve the performance of vinyl ester resin. Fiber reinforcement can improve the comprehensive properties such as the mechanical properties of the composite material by adding fibers to vinyl ester resin. However, there is a problem of interfacial incompatibility between the inorganic fiber reinforcement and vinyl ester resin, and phase separation is likely to occur between them, which will have a greater negative impact on the performance of the resin. In addition, adding inorganic fibers alone cannot significantly improve the flame retardant performance of vinyl ester resin. Therefore, the present invention provides a fiber-reinforced vinyl ester resin composite material, which can solve the problems existing in the prior art. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] Aiming at the deficiencies of the prior art, the present invention provides a fiber-reinforced vinyl ester resin composite material and a preparation method thereof.

[0006] (2) Technical Solutions

[0007] A preparation method of a fiber-reinforced vinyl ester resin composite material, the composite material is made of the following raw materials by weight:

[0008]

[0009] The preparation method includes the following steps:

[0010] Step 1: Weigh and mix each raw material according to parts by weight;

[0011] Step 2: Add bisphenol A vinyl ester resin and modified sepiolite fiber reinforcing additive into a mixer, start stirring, after mechanical stirring, then add antioxidant, accelerator and initiator into the mixer, and stir and mix evenly to form a premixed material;

[0012] Step 3: Pour the premixed material into a mold, after vacuum defoaming for 3 - 5 min, raise the temperature to 80 - 100 °C, and maintain at this temperature for 12 - 24 h, then take out to obtain the composite material.

[0013] As a further scheme of the present invention, the specific preparation method of the modified sepiolite fiber reinforcing additive includes the following steps:

[0014] Step S1: Use toluene diisocyanate to modify the surface of acidified sepiolite fiber to obtain functionalized modified sepiolite fiber;

[0015] Step S2: Use an organotin metal catalyst for catalysis, in a toluene medium, use a poly - high - molecular phosphorus - containing flame retardant as a modifier, and further react with the modified sepiolite fiber to obtain the modified sepiolite fiber reinforcing additive.

[0016] As a further scheme of the present invention, in step S1, the preparation method of the acidified sepiolite fiber is specifically as follows: Immerse sepiolite fiber in a hydrochloric acid solution with a concentration of 1 - 3 mol / L, stir at room temperature for 2 - 4 h, then separate the fiber material, and after washing and drying, it is ready.

[0017] As a further scheme of the present invention, in step S2, the organotin metal catalyst is any one of dibutyltin diacetate, dibutyltin dilaurate or stannous octoate.

[0018] In the above technical scheme, first, acidification treatment is carried out on sepiolite fiber to create favorable conditions for the next step of organic modification. Then, use toluene diisocyanate to modify the surface of sepiolite fiber, so that highly active isocyanate substituents are generated on the surface of sepiolite fiber to obtain functionalized modified sepiolite fiber. Then, under the catalytic action of an organotin metal catalyst, the isocyanate group can further carry out an aminosterification reaction with the active hydroxyl substituents in the structure of the poly - high - molecular phosphorus - containing flame retardant, so as to coat a large number of poly - high - molecular phosphorus - containing flame retardant molecular chains on the surface of sepiolite fiber to obtain the modified sepiolite fiber reinforcing additive.

[0019] As a further solution of the present invention, in step S2, the specific preparation method of the multi-polymer phosphorus-containing flame retardant includes the following steps:

[0020] Step SS1: Stir and mix L-malic acid, phosphorus oxychloride-containing phosphorus derivatives and tetrahydrofuran to form a homogeneous reaction solution. After that, introduce nitrogen gas, and add triethylamine to the reaction solution. After adding, control the heating rate at 2-4 °C / min, raise the temperature to 60-70 °C, keep warm for 3-6 h, then remove the nitrogen gas, discharge the material, and obtain a phosphorus-containing chain extender.

[0021] Step SS2: Sequentially add N,N-dimethylformamide and 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione to a polymerization kettle filled with nitrogen gas, start stirring. After forming a homogeneous reaction solution, add the phosphorus-containing chain extender to the polymerization kettle, and add a phase transfer catalyst. Then raise the temperature to 70-80 °C, carry out chain extension polymerization for 12-18 h, evaporate and remove the solvent, collect the material, and obtain the multi-polymer phosphorus-containing flame retardant.

[0022] As a further solution of the present invention, in step SS1, the phosphorus oxychloride-containing phosphorus derivative is any one of dibenzylphosphoryl chloride, 2-chloro-2-oxo-1,3,2-dioxaphospholane, or dimethyl chlorophosphate.

[0023] As a further solution of the present invention, in step SS2, the molar ratio of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione to the phosphorus-containing chain extender is 1:1-1.2.

[0024] As a further solution of the present invention, in step SS2, the phase transfer catalyst is any one of tetrabutylammonium hydrogensulfate, tetramethylammonium chloride, or tetrabutylammonium bromide.

[0025] Specifically, in step SS1, by using triethylamine to catalyze the reaction of the active hydroxyl group in the L-malic acid structure with P-Cl in the phosphorus oxychloride-containing phosphorus derivative structure, a phosphorus-containing chain extender containing two equivalents of carboxyl substituents is obtained. In step SS2, by using a phase transfer catalyst, the epoxy group in the 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione structure is continuously subjected to ring-opening esterification reaction with the phosphorus-containing chain extender to form a polymeric multi-polymer phosphorus-containing flame retardant.

[0026] As a further solution of the present invention, the antioxidant is antioxidant 1010 or antioxidant 168; the promoter is cobalt isooctanoate; the initiator is a peroxide initiator.

[0027] A fiber-reinforced vinyl ester resin composite material is prepared by the above preparation method.

[0028] (III) Beneficial technical effects

[0029] In the present invention, a multi-component polymer phosphorus-containing flame retardant is prepared to modify the surface of sepiolite fibers. On the one hand, the multi-component polymer phosphorus-containing flame retardant is equivalent to generating a "transition" structure between the sepiolite fibers and the vinyl ester resin, promoting good interfacial bonding force between them, improving their compatibility, and further enabling the sepiolite fibers to efficiently exert their own reinforcement and modification advantages and bear most of the external force, thereby improving the load-bearing capacity of the composite material. On the other hand, the structure of the multi-component polymer phosphorus-containing flame retardant contains a large number of triazine rings and phosphorus-containing flame retardant mechanisms, which can rapidly form an expanded carbon layer during the combustion of the composite material. This dense expanded carbon layer can effectively isolate oxygen and heat, preventing the combustion from continuing into the interior of the composite material, thereby effectively improving the flame retardant performance of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 It is an infrared analysis test chart of the multi-component polymer phosphorus-containing flame retardant. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below. Preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0033] Preparation Example 1

[0034] Preparation of modified sepiolite fiber-reinforced additive:

[0035] Step S1: Immerse sepiolite fibers in a hydrochloric acid solution with a concentration of 2 mol / L, stir at room temperature for 3 h, then separate the fiber material, and perform washing and drying treatments.

[0036] Step S2: Disperse 2.4 g of sepiolite fiber in 1,4-dioxane, and ultrasonically treat it until a homogeneous dispersion is formed. Then, add 6 g of toluene-2,4-diisocyanate to the dispersion, and then raise the temperature to 80 °C and keep it warm for 5 h to obtain functionalized modified sepiolite fiber;

[0037] Take 0.3 g of the functionalized modified sepiolite fiber as a test sample, and perform a titration test on the sample according to the hydrochloric acid-dibutylamine titration test method. The test results show that the percentage content of isocyanate groups in the sample is 7.59%;

[0038] Step S3: Ultrasonically disperse 1.6 g of the modified sepiolite fiber in toluene, then add 5 g of a multi-polymer phosphorus-containing flame retardant and 0.1 g of dibutyltin dilaurate. After adding, raise the temperature to 65 °C and keep stirring under nitrogen protection for 8 h to obtain a modified sepiolite fiber reinforced additive.

[0039] Same as Step S2, weigh the same weight of the modified sepiolite fiber reinforced additive for hydrochloric acid-dibutylamine titration test. The results show that the percentage content of isocyanate groups in the sample is 1.44%, indicating that the isocyanate groups of the modified sepiolite fiber are consumed during the reaction with the multi-polymer phosphorus-containing flame retardant.

[0040] The preparation method of the multi-polymer phosphorus-containing flame retardant includes the following steps:

[0041] Step SS1: Stir and mix 0.6 g of L-malic acid, 0.64 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane and tetrahydrofuran to form a homogeneous reaction solution. Then, introduce nitrogen, and add 0.1 g of triethylamine to the reaction solution. After adding, control the heating rate at 2 °C / min, raise the temperature to 70 °C, keep it warm for 4 h, then remove nitrogen and discharge to obtain a phosphorus-containing chain extender;

[0042] Step SS2: Sequentially add N,N-dimethylformamide and 0.4 g of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione to a polymerization kettle filled with nitrogen, start stirring. After a homogeneous reaction solution is formed, add 0.35 g of the phosphorus-containing chain extender to the polymerization kettle, and add 0.02 g of tetrabutylammonium bromide. Then, raise the temperature to 75 °C and carry out chain extension polymerization for 16 h. After that, evaporate and remove the solvent, collect the material to obtain a multi-polymer phosphorus-containing flame retardant.

[0043] Make the multi-polymer phosphorus-containing flame retardant into a potassium bromide tablet and perform infrared analysis test. The results are shown in Figure 1 , where the characteristic absorption peak at 3272 cm -1 is the characteristic absorption peak of the hydroxyl group generated during the ring-opening esterification reaction, and the characteristic absorption peak at 3020 cm-1 The characteristic absorption peak appearing at [1700 cm⁻¹] is the C-H absorption peak in the unsaturated alkenyl substituent. -1 ~[1800 cm⁻¹] -1 The characteristic absorption peak appearing at [1676 cm⁻¹] is the C=O characteristic absorption peak of the ester group and the carboxyl group in the excessive phosphorus-containing chain extender structure. -1 The characteristic absorption peak appearing at [1203 cm⁻¹] is the C=O characteristic absorption peak in the triazine ring structure. -1 The characteristic absorption peak appearing at [X cm⁻¹] is the P=O characteristic absorption peak.

[0044] Example 1

[0045] A fiber-reinforced vinyl ester resin composite material is made of the following raw materials by weight:

[0046]

[0047]

[0048] The preparation method of the composite material includes the following steps:

[0049] First step, weigh and mix each raw material according to the weight parts;

[0050] Second step, add bisphenol A vinyl ester resin and modified sepiolite fiber reinforcing additive to a mixer, start stirring, after mechanical mixing, then add antioxidant 168, cobalt isooctanoate and methyl ethyl ketone peroxide to the mixer, and stir and mix evenly to form a premixed material;

[0051] Third step, pour the premixed material into a mold, defoam under vacuum for 3 min, then raise the temperature to 80 °C, and keep it at this temperature for 24 h, take out, and the composite material can be obtained.

[0052] The preparation method of the modified sepiolite fiber reinforcing additive refers to Preparation Example 1, and the same applies hereinafter.

[0053] Example 2

[0054] A fiber-reinforced vinyl ester resin composite material is made of the following raw materials by weight:

[0055]

[0056] The preparation method of the composite material includes the following steps:

[0057] First step, weigh and mix each raw material according to the weight parts;

[0058] Note: In the original text, the value of the P=O characteristic absorption peak is not given, so it is represented by [X cm⁻¹] in the translation. Also, the unit "cm" in the original text is assumed to be "cm⁻¹" for the purpose of translation to make it a more common unit for absorption peak representation in spectroscopy.Step 2: Add bisphenol A vinyl ester resin and modified sepiolite fiber reinforcing additive into a mixer, start stirring, after mechanical mixing, then add antioxidant 1010, cobalt isooctanoate and methyl ethyl ketone peroxide into the mixer, and stir and mix evenly to form a premix;

[0059] Step 3: Pour the premix into a mold, defoam under vacuum for 4 min, then raise the temperature to 90 °C, and maintain at this temperature for 18 h, take out, and then the composite material can be obtained.

[0060] Example 3

[0061] A fiber-reinforced vinyl ester resin composite material is made of the following raw materials by weight:

[0062]

[0063] The preparation method of the composite material includes the following steps:

[0064] Step 1: Weigh and prepare each raw material according to the weight parts;

[0065] Step 2: Add bisphenol A vinyl ester resin and modified sepiolite fiber reinforcing additive into a mixer, start stirring, after mechanical mixing, then add antioxidant 1010, cobalt isooctanoate and methyl ethyl ketone peroxide into the mixer, and stir and mix evenly to form a premix;

[0066] Step 3: Pour the premix into a mold, defoam under vacuum for 5 min, then raise the temperature to 100 °C, and maintain at this temperature for 12 h, take out, and then the composite material can be obtained.

[0067] Comparative Example 1

[0068] A fiber-reinforced vinyl ester resin composite material is made of the following raw materials by weight:

[0069]

[0070] The preparation method of the composite material includes the following steps:

[0071] Step 1: Weigh and prepare each raw material according to the weight parts;

[0072] Step 2: Add bisphenol A vinyl ester resin and sepiolite fiber into a mixer, start stirring, after mechanical mixing, then add antioxidant 1010, cobalt isooctanoate and methyl ethyl ketone peroxide into the mixer, and stir and mix evenly to form a premix;

[0073] Step 3: Pour the premix into a mold. After vacuum defoaming for 4 min, raise the temperature to 90 °C and hold at this temperature for 18 h. Then take it out to obtain the composite material.

[0074] Comparative Example 2

[0075] A fiber-reinforced vinyl ester resin composite material is made from the following raw materials by weight:

[0076]

[0077] The preparation method of the composite material includes the following steps:

[0078] Step 1: Weigh and prepare each raw material according to the weight parts.

[0079] Step 2: Add bisphenol A vinyl ester resin and polyfunctional high molecular phosphorus flame retardant into a mixer, start stirring, and after mechanical mixing, add antioxidant 1010, cobalt isooctanoate and methyl ethyl ketone peroxide into the mixer and stir evenly to form a premix.

[0080] Step 3: Pour the premix into a mold. After vacuum defoaming for 4 min, raise the temperature to 90 °C and hold at this temperature for 18 h. Then take it out to obtain the composite material.

[0081] Comparative Example 3

[0082] A fiber-reinforced vinyl ester resin composite material is made from the following raw materials by weight:

[0083]

[0084]

[0085] The preparation method of the composite material includes the following steps:

[0086] Step 1: Weigh and prepare each raw material according to the weight parts.

[0087] Step 2: Add bisphenol A vinyl ester resin, antioxidant 1010, cobalt isooctanoate and methyl ethyl ketone peroxide into a mixer and stir evenly to form a premix.

[0088] Step 3: Pour the premix into a mold. After vacuum defoaming for 4 min, raise the temperature to 90 °C and hold at this temperature for 18 h. Then take it out to obtain the composite material.

[0089] Test Example

[0090] The composite materials in the examples and comparative examples were cut into test samples that met the specifications, and the following tests were carried out. The results are recorded in Table 1:

[0091] Table 1 - Test Results

[0092] Tensile strength / MPa <![CDATA[Impact strength / kJ / m 2 > Flexural strength / MPa Limiting oxygen index / % Example 1 83.4 23.4 119.1 32.1 Example 2 84.1 23.8 119.7 32.3 Example 3 83.5 23.3 119.6 31.9 Comparative example 1 77.9 17.9 108.2 19.8 Comparative example 2 68.2 14.1 99.7 31.5 Comparative example 3 60.7 12.6 86.9 19.0

[0093] The reference standard for tensile strength test is GB / T 1040.3 - 2006; the reference standard for impact strength test is GB / T 9341 - 2008; the reference standard for flexural strength test is GB / T 1843 - 2008; the reference standard for limiting oxygen index test is GB / T 2406.2 - 2009.

[0094] Enlightened by the ideal embodiments of the present invention, through the above description, relevant personnel can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A method for preparing a fiber-reinforced vinyl ester resin composite material, characterized in that: The composite material is made of the following raw materials in parts by weight: The preparation method comprises the following steps: The first step is to weigh and prepare all the raw materials according to the weight proportions; The second step is to add bisphenol A vinyl ester resin and modified sepiolite fiber reinforcement additive into a mixer, start stirring, and after mechanical mixing, add antioxidant, accelerator and initiator into the mixer, stir and mix to form a premix; Step 3: Pour the premix into the mold, vacuum defoam for 3-5 minutes, raise the temperature to 80-100°C, and keep it at this temperature for 12-24 hours, then take it out to obtain the composite material; The specific preparation method of the modified sepiolite fiber reinforcement additive comprises the following steps: Step S1, using toluene diisocyanate to perform surface modification on the acidified sepiolite fiber to obtain functionalized modified sepiolite fiber; Step S2, using an organic metal tin catalyst for catalysis, in a toluene medium, using a multi-polymer phosphorus-containing flame retardant as a modifier, and further reacting with the modified sepiolite fiber to obtain a modified sepiolite fiber reinforcement additive; The multi-polymer phosphorus-containing flame retardant is firstly prepared by using L-malic acid and phosphorus-containing derivatives of phosphorus oxychloride as reactants to prepare a phosphorus-containing chain extender, and then using the phosphorus-containing chain extender and 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione to carry out continuous ring-opening esterification reaction to prepare the flame retardant.

2. The method for preparing a fiber-reinforced vinyl ester resin composite material according to claim 1, characterized in that: In step S1, the preparation method of the acidified sepiolite fiber is specifically as follows: immersing the sepiolite fiber in a hydrochloric acid solution with a concentration of 1-3 mol / L, stirring at room temperature for 2-4 hours, separating the fiber material, and washing and drying the fiber material.

3. The method for preparing a fiber-reinforced vinyl ester resin composite material according to claim 1, characterized in that: In step S2, the organic metal tin catalyst is any one of dibutyltin diacetate, dibutyltin dilaurate or stannous octoate.

4. The method for preparing a fiber-reinforced vinyl ester resin composite material according to claim 1, characterized in that: In step S2, the specific preparation method of the multi-polymer phosphorus-containing flame retardant comprises the following steps: Step SS1, L-malic acid, phosphorus oxychloride-type phosphorus-containing derivatives and tetrahydrofuran are stirred and mixed to form a uniform reaction solution, nitrogen is introduced, and triethylamine is added to the reaction solution. After the addition is completed, the heating rate is controlled to be 2-4°C / min, and the temperature is raised to 60-70°C. After keeping the temperature for 3-6 hours, the nitrogen is removed, and the material is discharged to obtain a phosphorus-containing chain extender; Step SS2, add N,N-dimethylformamide and 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione in sequence to a polymerization kettle filled with nitrogen, start stirring, and after a homogeneous reaction liquid is formed, add the phosphorus-containing chain extender to the polymerization kettle, and add a phase transfer catalyst, then increase the temperature to 70-80°C, after chain extension polymerization for 12-18 hours, evaporate and remove the solvent, collect the material, and obtain a multi-polymer phosphorus-containing flame retardant.

5. The method for preparing a fiber-reinforced vinyl ester resin composite material according to claim 4, characterized in that: In step SS1, the phosphorus oxychloride-based phosphorus-containing derivative is any one of dibenzyl phosphorus oxychloride, 2-chloro-2-oxo-1,3,2-dioxaphospholane or dimethyl chlorophosphate.

6. The method for preparing a fiber-reinforced vinyl ester resin composite material according to claim 4, characterized in that: In step SS2, the molar ratio of the 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione to the phosphorus-containing chain extender is 1:1-1.

2.

7. The method for preparing a fiber-reinforced vinyl ester resin composite material according to claim 4, characterized in that: In step SS2, the phase transfer catalyst is any one of tetrabutylammonium hydrogen sulfate, tetramethylammonium chloride or tetrabutylammonium bromide.

8. The method for preparing a fiber-reinforced vinyl ester resin composite material according to claim 1, characterized in that: The antioxidant is antioxidant 1010 or antioxidant 168; the accelerator is cobalt isooctanoate; and the initiator is a peroxide initiator.

9. A fiber-reinforced vinyl ester resin composite material, characterized in that: The method is prepared according to any one of claims 1 to 8.

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