Preparation Method and Application of an Epoxy Resin-Based Prepreg

Abstract

The present invention discloses a method for preparing prepreg and its application. The raw materials for preparing the prepreg contain the following components: (A) epoxy resin component, (B) isocyanate component, (C) isocyanate-reactive component, and (D) reinforcing material component. An addition reaction occurs between the isocyanate component (B) and the isocyanate-reactive component (C) in the reinforcing material component (D) containing the epoxy resin component (A) to generate a prepolymer, thereby preparing the prepreg. In the later stage, the epoxy resin component (A) in the prepreg undergoes ring-opening polymerization or other reactions to form a crosslinked network structure, thus completing the curing process and obtaining the corresponding composite material.

Description

Technical Field

[0001] The present invention relates to a preparation method and application of an epoxy resin-based prepreg, belonging to the field of composite materials. Technical Background

[0002] Due to its excellent mechanical properties and the ability to precisely control the fiber volume content, epoxy resin-based prepregs are increasingly widely used in the manufacture of large composite components, such as wind turbine blades and automotive composite components.

[0003] Currently, in epoxy resin prepregs, due to the specific physical properties of epoxy resin itself, the epoxy-based prepregs are relatively brittle and have low toughness. To overcome this defect, high-toughness resins such as polyurethane and polyurea are often used to modify epoxy, thereby improving the resin toughness. In addition, during the production process, the wettability between the resin and the reinforcing fiber material plays a crucial role in the physical properties of the composite material. Poor wettability between the resin liquid and the reinforcing fiber will result in defects at the composite interface between the resin and the fiber, leading to obvious changes in the physical properties of the composite material.

[0004] CN 103524703A discloses a preparation method of a polyurethane / epoxy resin composite material, which is mainly obtained by mixing component A and component B. Component A is a terminal isocyanate group polyurethane prepolymer, and component B is a binary aromatic amine-terminated epoxy resin. After component A and component B are mixed in a certain proportion, they are cured and formed. It mainly utilizes the reaction activity of the isocyanate group and the amino group to graft the epoxy resin onto the polyurethane prepolymer during the curing process, thereby modifying the epoxy resin.

[0005] CN 106397706A discloses a high-strength epoxy-modified polyurethane composite material and its preparation method. It mainly uses the prepolymer method to prepare component A and component B in a closed environment. Component A is a mixture of a terminal isocyanate prepolymer and an epoxy resin, and component B is a mixture of a chain extender and a catalyst. During the prepolymerization process, it mainly grafts the epoxy resin onto the polyurethane prepolymer by using the reaction of the epoxy group, the hydroxyl group and the isocyanate group, thereby carrying out modification.

[0006] CN 103113604B discloses a preparation method for a polyurethane prepolymer to improve the interlaminar shear strength of a prepreg cured at medium and low temperatures. First, a terminal isocyanate polyurethane prepolymer obtained by reacting isocyanate and polyether polyol in a controllable ratio is reacted and grafted onto bisphenol-type epoxy resin, and an epoxy resin composition is added to obtain a toughened and modified epoxy resin matrix. Then, it is mixed evenly with a curing agent and a promoter component to be used as a prepreg matrix material.

[0007] From the above epoxy resin-based prepreg preparation process and the disclosed prior art, the current epoxy resin-based prepregs have the following problems: In the process of toughening epoxy resin, high-toughness resin prepolymers (such as polyurethane, polyurea resin, etc.) are required to react with epoxy resin to graft the toughened part into the epoxy resin, which adds an additional resin synthesis process, increases the complexity of synthesis and the corresponding cost, and is not conducive to the preparation process of epoxy resin-based prepregs. Summary of the Invention

[0008] The technical problems to be solved by the present invention are: To overcome the deficiencies and defects mentioned in the above technical background, to provide an epoxy resin for high-toughness prepregs, and to provide a preparation method for epoxy resin-based prepregs.

[0009] The idea of the technical solution of the present invention is: Utilizing the high reactivity of isocyanate and organic amine compounds, a prepolymer is formed on the reinforcing material containing epoxy resin components by reacting the isocyanate component and the isocyanate-reactive component. This prepolymer acts as a resin adhesive to wrap the epoxy resin components and the reinforcing material components to form a prepreg. The excess amino groups in the prepreg act as curing agents to catalyze the polymerization reaction of epoxy resin at a certain temperature, thereby achieving curing and obtaining the corresponding composite material. In addition, the substance of formula (I) structure added in the isocyanate-reactive component can act as a promoter to promote the polymerization of epoxy resin and the participation of amino groups in the polyurea in the ring-opening polymerization reaction of epoxy resin, thereby grafting the polyurea onto the epoxy resin to achieve toughening of the epoxy resin. It was also found in the experiment that the promoter performance of the substance of formula (I) structure is significantly greater than the sum of tertiary amine and alcohol promoters, and the addition of the substance of formula (I) structure also significantly improves the wetting between the resin and the reinforcing fiber material.

[0010] The technical solution of the present invention is as follows:

[0011] An epoxy resin-based prepreg, the raw materials comprising the following components:

[0012] (A) Epoxy resin components, the epoxy resin components comprising one or more common epoxy resin components;

[0013] (B) Isocyanate component; the content is 10 - 60 wt.%, based on the weight of the epoxy resin components;

[0014] The isocyanate component comprises one or more organic isocyanates, the functionality of the isocyanate component is 2 - 5, and the NCO content of the isocyanate component is 12 - 48%;

[0015] (C) Isocyanate-reactive component, comprising:

[0016] (C1) Organic amine compound component, the content is 10 - 60 wt.%, based on the weight of the epoxy resin components;

[0017] The organic amine compound component contains one or more compounds containing primary or secondary amino groups with a functionality greater than or equal to 2;

[0018] (C2) One or more compounds of formula (I), the content of the compound of formula (I) being 0.1-5 wt.%, based on the weight of the epoxy resin component:

[0019]

[0020] wherein R1, R2, R3 are selected from alkyl groups having 1-16 carbon atoms, cycloalkyl groups having 3-16 carbon atoms, 2,2-bis(4-phenylene)-propane, 1,4-bis(methylene)benzene, 1,3-bis(methylene)benzene, 1,2-bis(methylene)benzene; n is 1; wherein, R1, R2, R3 can be independent of each other, and part or all of the structures of R1, R2, R3 can also be combined with each other to form a cyclic structure;

[0021] (D) A reinforcing material component, the content of the reinforcing material component being 0-90 wt.%, and its content being based on the total weight of the epoxy resin component (A), the isocyanate component (B), and the isocyanate-reactive component (C).

[0022] wherein,

[0023] Epoxy resin component (A)

[0024] The "epoxy resin component (A)" described herein refers to various epoxy resins commonly used in the art, which are high molecular weight oligomers containing two or more epoxy groups, having a skeleton of aliphatic, cycloaliphatic or aromatic organic compounds and capable of forming useful thermosetting or thermoplastic products through epoxy group reactions.

[0025] In the present invention, the epoxy resin component (A) includes, but is not limited to, one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, polyphenol glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester epoxy resin, unsaturated modified epoxy resin, polyurethane modified epoxy resin, special epoxy resin, or a composition of the above epoxy resins.

[0026] Isocyanate component (B)

[0027] The "isocyanate component (B)" described herein refers to common organic isocyanate monomers, isocyanate prepolymers, epoxy modified isocyanates, unsaturated modified isocyanates, phenolic modified isocyanates and mixtures thereof in the art,

[0028] The isocyanate component (B) includes, but is not limited to, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), 1,4-cyclohexane diisocyanate (CHDI), xylylene diisocyanate (XDI), cyclohexane dimethylene diisocyanate (HXDI), trimethyl-1,6-hexamethylene diisocyanate (TMHDI), tetramethylxylylene diisocyanate (TMXDI), norbornane diisocyanate (NBDI), dimethylbiphenyl diisocyanate (TODI), methylcyclohexyl diisocyanate (HTDI), tetramethylene diisocyanate, 2-methylpentamethylene diisocyanate, dodecamethylene diisocyanate, 4,4'-diisocyanato-3,3'-dimethyl dicyclohexylmethane, 4,4'-diisocyanato-2,2-dicyclohexylpropane, poly(hexamethylene diisocyanate), octamethylene diisocyanate, toluene-α,4-diisocyanate, 2,4,6-trimethyl-1,3-phenylene diisocyanate, 4-chloro-6-methyl-1,3-phenylene diisocyanate, poly[1,4-phenylene diisocyanate-co-poly(1,4-butylene glycol)] diisocyanate, poly(tetrafluoroethylene oxide-co-difluoromethyleneoxy)α,ω-diisocyanate, 1,4-butane diisocyanate, 1,8-octane diisocyanate, 1,3-bis(1-isocyanato-1-methylethyl)benzene, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, naphthalene-1,5-diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 4,4'-, 2,4'- or 2,2'-diphenylmethane diisocyanate or mixtures of these isomers, 4,4'-, 2,4'- or 2,2'-diisocyanato-2,At least one of 2-diphenylpropane, terephthalylidene diisocyanate, and the above-mentioned isocyanate prepolymers and modified products, preferably at least one of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), 1,4-cyclohexane diisocyanate (CHDI), xylylene diisocyanate (XDI), cyclohexylene dimethylene diisocyanate (HXDI), trimethyl-1,6-hexamethylene diisocyanate (TMHDI), tetramethyl-m-xylylene diisocyanate (TMXDI), norbornane diisocyanate (NBDI), dimethylbiphenyl diisocyanate (TODI), methylcyclohexyl diisocyanate (HTDI), and the above-mentioned isocyanate prepolymers and modified products, more preferably at least one of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), and the above-mentioned isocyanate prepolymers and modified products.,

[0029] Organic amine compound component (C1)

[0030] The organic amine compound component (C1) comprises one or more compounds, polymers, or mixtures thereof containing primary or secondary amino groups with a functionality greater than or equal to 2.

[0031] In the examples of the present invention, the organic amine compound component includes, but is not limited to, one or several of C2-C30 aliphatic amines, C4-C30 cycloaliphatic amines, C8-C30 aromatic amines, polyamide polyamines, and modified polyamines such as epoxy compound-added polyamines, Michael addition polyamines, Mannich addition polyamines, ketone-blocked polyamines, and eutectic mixed polyamines. For example, ethylenediamine, 3,3'-dimethyl-4,4-diaminodicyclohexylmethane, 3-azetidinamine, 4,4-bispiperidine, 1,3-bis(4-piperidyl)propane, p-phenylenediamine, N-phenylethylenediamine, 1,4-diazabicyclo[2.2.2]octane.

[0032] Component (C2) of formula (I) structure

[0033] The "component of formula (I) or formula structure (C2)" described in the text refers to one or more compounds conforming to the structural formula (I).

[0034] In an embodiment of the present invention, the component (C2) of the formula (I) structure includes, but is not limited to, one or more of dimethylaminobutanol, diethylaminobutanol, dimethylaminopentanol, diethylaminopentanol, 5-(diethylamino)pentylethanol, 6-dimethylamino-1-hexanol, 2-(1-methyl-3-piperidinyl)-1-ethanol, 1-benzyl-4-hydroxypiperidine, 8-dimethylamino-1-octanol, and (N,N-diethyl)-4-amino-1-butanol.

[0035] Reinforcing material component (D)

[0036] As used herein, " Reinforcing material component (D) " refers to common reinforcing materials in the art.

[0037] The reinforcing materials include, but are not limited to, glass fiber (fiberglass), carbon fiber (carbon fiber), polyester fiber, natural fiber, aromatic polyamide fiber, nylon fiber, basalt fiber, boron fiber, silicon carbide fiber, asbestos fiber, whisker, metal fiber, or a mixture of the above materials.

[0038] In the present invention, the amount of isocyanate groups in the isocyanate component (B) is denoted as N1, and the amount of amino groups in the organic amine compound component (C1) is denoted as N2, where N2:N1 is 1.1 - 3.

[0039] The present invention further relates to a method for preparing the above prepreg.

[0040] The prepreg preparation process can adopt common processes in the art, such as hand lay-up molding process: reacting the isocyanate component (B) and the isocyanate-reactive component (C) in the reinforcing material component (D) containing the epoxy resin component (A) to form a prepolymer, thereby preparing the prepreg.

[0041] The present invention further relates to a composite material.

[0042] The composite material completes the curing process through ring-opening polymerization reaction or other reactions to form a crosslinked network structure of the epoxy resin component (A) in the prepreg, and obtains the corresponding composite material; the curing temperature is 80°C - 270°C, and the curing duration is 0.1 - 4 h.

[0043] The composite material can be applied to fields including, but not limited to, aerospace, automotive industry, chemical textile and machinery manufacturing, medicine, biology, construction, pipelines, etc.

[0044] In the present invention, one or more accelerators or inhibitors, such as amines, phenols, substituted ureas, imidazoles and their salts, boron trifluoride complexes, metal organic salts, phosphines, acyl halides, organic acids, inorganic acids, etc., may also be present during the preparation process of the epoxy resin-based prepreg or during the curing process of the epoxy resin-based prepreg to control the reaction rate and optimize the reaction process.

[0045] In the present invention, the epoxy resin may also contain some functional aids or additives. The functional aids and additives include, but are not limited to, chain extenders, small molecule raw materials, internal mold release agents, flame retardants, fillers, pigments, antioxidants, foaming agent stabilizers, light stabilizers, auxiliary antioxidants, hydrolysis stabilizers, bactericidal and mildew-proof agents, defoamers, rheology modifiers, leveling agents, wetting agents, reactive diluents, coupling agents, color pastes, catalysts, water scavengers, molecular sieves, or mixtures of the above aids and additives. The above components can be stored independently outside the epoxy resin system, can be added thereto after preparing the polyurethane polymer, or can be added thereto during the preparation process of the epoxy resin.

[0046] The beneficial effects of the present invention are as follows:

[0047] By utilizing the high reactivity of isocyanates and organic amine compounds, it is possible to prepare an epoxy resin-based prepreg at room temperature. By introducing an accelerator having the structure of formula (I) into the reaction system, toughening and strengthening of the epoxy resin can be achieved, and the performance of the accelerator of the structure of formula (I) is significantly greater than the sum of the performance of the same type of tertiary amine and alcohol accelerators. In addition, the substances of the structure of formula (I) also help to improve the wetting effect between the fiber and the resin and reduce the internal defects of the composite material. Detailed implementation manners

[0048] The present invention will be further described below in conjunction with specific embodiments. However, it should be understood that these embodiments are only used to illustrate the present invention and do not constitute a limitation to the scope.

[0049] In the following embodiments, the specific experimental methods are not specified and are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Unless otherwise specified, all percentages and parts are calculated by weight.

[0050] In the following examples and comparative examples, the temperature during the prepreg preparation process is 25°C; the curing temperature during the process of curing the prepreg into a composite material is about 140°C, the time is 1 - 3 hours, and after cooling, the physical properties are tested according to the following standards:

[0051] The test standard for the flexural modulus is: DIN ISO 527;

[0052] The test standard for the flexural strength is: DIN ISO 527;

[0053] The tensile strength test standard is: DIN ISO 527;

[0054] The elongation at break test standard is: DIN ISO 527;

[0055] Impact strength test standard: GB 1451-2005.

[0056] The raw materials used in the examples are as follows:

[0057] Epoxy resin component (A):

[0058] E51 epoxy resin, purchased from McLean;

[0059] Isocyanate component (B):

[0060] WANNATE PM200, NCO content 31.2wt%, viscosity 200mPa.s at 25°C, Wanhua Chemical;

[0061] WANNATE MDI50, NCO content 33.5wt%, viscosity 10mPa.s at 25°C, Wanhua Chemical;

[0062] Organic amine compound component (C1):

[0063] 3,3'-Dimethyl-4,4-diaminodicyclohexylmethane was purchased from Sigma-Aldrich;

[0064] Formula (I) structural substance (C2):

[0065] 6-Dimethylamino-1-hexanol, purchased from Aladdin;

[0066] 2-(1-methyl-3-piperidinyl)-1-ethanol, purchased from Aladdin;

[0067] 3-Dimethylamino-3-phenylpropanol, purchased from Maclean

[0068] 1-Benzyl-4-hydroxypiperidine was purchased from Sigma-Aldrich;

[0069] Reinforcement component (D):

[0070] Fiberglass cloth EWR400, purchased from China Jushi Co., Ltd.;

[0071] Materials used in comparison ratio:

[0072] n-Hexanol, purchased from Aladdin

[0073] N,N-Dimethyloctylamine was purchased from Sigma-Aldrich.

[0074] Examples 1-4 and Comparative Examples 1-4

[0075] The prepreg preparation process is as follows: an addition reaction occurs between the isocyanate component (B) and the isocyanate-reactive component (C) in the reinforcing material component (D) containing the epoxy resin component (A) to generate a prepolymer, and the prepreg is prepared. Among them, the amounts of each component in each example and comparative example are shown in Table 1 and Table 2 respectively, and the amounts in the table represent parts by mass.

[0076] Table 1 Examples

[0077]

[0078] Note: The amount of glass fiber in the above prepregs is 65 parts by mass.

[0079] Table 2. Comparative Examples

[0080]

[0081] Note: (1) To ensure the consistency of the promotion effect, the amount of substance of the tertiary amino group and / or hydroxyl group in the substance of formula (1) in Example 1 and Comparative Examples 2-4 is kept the same. The amount of glass fiber in the prepregs is 65 parts by mass.

[0082] Perform performance tests on the composites prepared from the prepregs of the examples and comparative examples, and the test results are listed in Tables 3 and 4:

[0083] Table 3 Performance of Composites Prepared from Example Prepregs

[0084]

[0085]

[0086] Table 4 Performance of Composites Prepared from Comparative Example Prepregs

[0087]

[0088] It can be seen from the physical properties of the composite materials in the examples that by adjusting the usage amounts of isocyanate and organic amine compounds in the resin, the toughness of the prepreg-based composite materials can be effectively improved, indicating that this method can obtain high-performance composite materials.

[0089] By comparing the physical properties of the composite materials in Example 4 and Comparative Examples 1-4, it can be found that introducing substances of Structural Formula (I) into the epoxy prepreg can achieve toughening and strengthening of epoxy resin, and the performance of the accelerator of the Structural Formula (I) type is significantly greater than the sum of the same type of tertiary amine and alcohol accelerators. Moreover, during the preparation process, after adding the substance structure of the Structural Formula (I) type, the porosity between the composite materials is significantly reduced, indicating that the interfacial combination between the resin and the fiber is good, and no defects occur during the infiltration process as in the case without the substance structure of the Structural Formula (I) type.

Claims

1. An epoxy resin-based prepreg, the raw materials comprising the following components: (A) An epoxy resin component; (B) An isocyanate component; the content is 10-60 wt.%, based on the weight of the epoxy resin component; (C) An isocyanate-reactive component, comprising: (C1) An organic amine compound component, the content is 10-60 wt.%, based on the weight of the epoxy resin component; (C2) One or more compounds, the content of the compounds is 0.1-5 wt.%, based on the weight of the epoxy resin component: The compounds are selected from one or more of dimethylamine butanol, diethylamine butanol, dimethylamine pentanol, diethylamine pentanol, 6-dimethylamino-1-hexanol, 2-(1-methyl-3-piperidinyl)-1-ethanol, 1-benzyl-4-hydroxypiperidine, 8-dimethylamino-1-octanol, 3-dimethylamino-3-phenylpropanol; (D) A reinforcing material component, the content of the reinforcing material component is 0-90 wt.%, based on the total weight of the epoxy resin component (A), the isocyanate component (B), and the isocyanate-reactive component (C).

2. The prepreg according to claim 1, characterized in that, The molar ratio of the isocyanate group in the isocyanate component (B) to the amino group in the organic amine compound component (C1) is 1:1.1-3.

3. The prepreg according to claim 1 or 2, characterized in that, The epoxy resin component (A) includes at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, polyphenol glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester epoxy resin, unsaturated modified epoxy resin, polyurethane modified epoxy resin, special epoxy resin.

4. The prepreg according to any one of claims 1-2, characterized in that, The functionality of the isocyanate component is 2-5, and the NCO content is 12-48%.

5. The prepreg according to any one of claims 1-2, characterized in that The organic amine compound component (C1) contains one or more compounds and polymers containing primary or secondary amino groups with a functionality greater than or equal to 2.

6. The prepreg according to claim 5, characterized in that, The organic amine compound component (C1) is selected from at least one of ethylenediamine, 3,3'-dimethyl-4,4-diaminodicyclohexylmethane, 3-aminoazetidine, 4,4-bispiperidine, 1,3-bis(4-piperidyl)propane, p-phenylenediamine, N-phenylethylenediamine, 1,4-diazabicyclo[2.2.2]octane.

7. The prepreg according to claim 1, characterized in that, The reinforcing material includes at least one of glass fiber, carbon fiber, polyester fiber, natural fiber, nylon fiber, basalt fiber, boron fiber, silicon carbide fiber, asbestos fiber, whisker, metal fiber.

8. A composite material cured from the prepreg according to any one of claims 1-7.

9. Use of the composite material according to claim 8, the composite material is applied to fields including aerospace, automotive industry, chemical textile and machinery manufacturing, medicine, biology, construction, pipelines.

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