KR20170093013A - Resin composition for producing high temperature heat resistingprepreg and method for producing the same - Google Patents

Abstract

The present invention relates to a resin composition for producing a high-temperature heat resistant prepreg and a method for producing the same. The present invention relates to a process for preparing a monomer mixture by mixing an aromatic diamine, an aromatic dianhydride and an anhydride in a solvent in a molar ratio of n + 1: n: 2 to prepare a monomer mixture, And a step of imidizing the monomer mixture impregnated in the fiber sheet. The present invention also provides a process for producing a high-temperature heat resistant prepreg comprising the steps of: The thermosetting resin included in the prepreg according to the present invention has a glass transition temperature of 370 DEG C or higher and maintains stable physical properties at a high temperature. As a result, the prepreg according to the present invention has better heat resistance than other thermosetting resin prepregs.

Description

Technical Field [0001] The present invention relates to a resin composition for preparing a high-temperature heat resistant prepreg,

The present invention relates to a resin composition for producing a high-temperature heat resistant prepreg and a method for producing the same.

When designing aircraft, rockets, etc., one of the important things is the total weight. This has a direct impact on the machine's range, performance, maneuverability, and operating costs. As a result, the aerospace industry continues to strive to find lighter, stronger materials. In the aerospace industry, the most widely used composite material classification is a polymer matrix composite containing a polymer matrix, which may vary in properties depending on the strength of the fiber. When high physical properties are required, the structure of the fiber transmits the load, which directly affects the strength and stiffness of the composite material. While the fiber prevents deformation from the external force, the polymer matrix is subjected to a load It plays a secondary role as a forwarder.

A composite material refers to a material having two or more materials having different compositions or shapes and having an effective function by being combined so as to have macroscopically separated interfaces therebetween. However, alloys with microscopic homogeneity of more than two kinds of materials are not called composites, and composites differ from alloys in that they have macroscopically boundaries between constituent materials. Composite materials can be broadly classified into reinforcement and matrix. Composite materials composed of these elements can be generally classified into layered composite materials, particle reinforced composite materials, and fiber reinforced composite materials. have. Properties that can be improved as composite materials include strength and stiffness, corrosion resistance, fatigue life, abrasion resistance, impact properties, heat resistance, electrical insulation, heat insulation, light weight and appearance.

The raw materials of composite materials are divided into reinforcing fibers and matrix materials. The reinforcing material of the composite material mainly uses continuous fibers. Historically, fiberglass is the oldest reinforcing fiber, but the frequency and importance of its use is high for carbon fiber (graphite fiber or carbon fiber). Aramid fibers typified by Kevlar are widely used. Ceramic fibers such as boron fiber and silicon carbide, which are less frequently used, are also used.

If the reinforcing fiber is a load-bearing element, the need for a matrix material is imperative to achieve a structural shape by fixing each of these fibers in place. In addition, when the shear stress is applied, since the matrix material mainly supports the load, its mechanical properties are very important and it has a decisive influence on the progress of the fracture. Also, since most of the fibers are stable to external elements (heat, chemicals, etc.), resistance of the matrix to such external elements is often important. Unsaturated polyester resin is a major part of general composites. Epoxy resins are used for advanced composites. Unsaturated polyester resins are also used for composites. For high temperature applications, phenol, polyimide resin and aluminum are used. Recently, thermoplastic resins have been widely used.

On the other hand, thermosetting polymers are most commonly used in the aerospace industry. These thermosetting polymers are characterized by a high crosslinking structure during the curing process and can not be reprocessed after initial change and are decomposed at high temperatures. The most commonly used types of thermosetting are unsaturated polyesters, epoxies, vinyl esters and polyimides. Epoxies are frequently used in aircraft and missile structures because they have suitable mechanical properties in thermosetting polymers, but polyimides are suitable for high temperature applications in the aerospace industry. Because of these properties, polyimides are emerging as the base material for high performance composite materials in today's industries, and continuous research has led to a new field of polyimide, polymerisation of monomeric reactants (PMR). In the mid-1970s, the NASA Lewis Research Center developed the PMR-15 (Mw 1500), which is stable at high temperatures with low cost and simple process. Compared with other polymer resins, PMR-15 has excellent stability of oxidation and mechanical properties at high temperatures and was used for engine parts. However, as the aerospace industry develops, polymer resins that can be used at higher temperatures are required to be developed and suitable resins must be developed.

It is an object of the present invention to provide a method for producing a prepreg, a prepreg, and a prepreg for producing a prepreg having a high glass transition temperature and being usable even in a high temperature environment.

In order to accomplish the above object, the present invention provides a process for producing a polyamic acid by mixing an aromatic diamine, an aromatic dianhydride and an anhydride in a molar ratio of n + 1: n: 2, wherein the aromatic diamine is 3,4- oxydianiline, 4,4'-oxydianiline, p-Phenylene diamine, 4,4 '- (9-fluorenylidene) 4 '- (9-Fluorenylidene) dianiline, and 1,3-bis (4-aminophenoxy) benzene. The aromatic dianhydride The rides were 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride (3,3', 4,4'-benzophenonetetracarboxylic dianhydride), 3,3 ', 4,4'-biphenyltetracar (3,3 ', 4,4'-biphenyltetra carboxylic dianhydride), 3,3', 4,4'-oxydiphtalic dianhydride ), 4,4'-bisphenol A dianhydride (4,4'-Bisphe nol A dianhydride, and pyro mellitic dianhydride. The present invention also provides a mixture for preparing a prepreg.

The present invention also relates to a process for preparing a monomer mixture comprising mixing an aromatic diamine, an aromatic dianhydride and an anhydride in a solvent at a molar ratio of n + 1: n: 2 to prepare a monomer mixture, And a step of imidizing the monomer mixture impregnated in the fiber sheet. The present invention also provides a method for producing a prepreg for high temperature heat resistance.

In one embodiment, the aromatic diamine is 3,4-oxydianiline, 4,4'-oxydianiline, para-phenylenediamine (p- Phenylene diamine, 4,4 '- (9-fluorenylidene) dianiline, 1,3-bis (4-aminophenoxy) benzene -bis (4-aminophenoxy) benzene).

In one embodiment, the aromatic dianhydride is 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic dianhydride, , 4,4'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-oxydiphthalic dianhydride (3,3', 4,4'- 3 ', 4,4'-oxydiphtalic dianhydride, 4,4'-Bisphenol A dianhydride, and pyro mellitic dianhydride. .

In one embodiment, the anhydride may be a nadic anhydride.

In one embodiment, the step of preparing the monomer mixture comprises: esterifying the aromatic dianhydride and the anhydride, respectively, and reacting the aromatic diamine, the esterified aromatic dianhydride, and the esterified anhydride, And mixing the rye with a solvent in a molar ratio of n + 1: n: 2.

In one embodiment, the step of imidizing the monomer mixture may be carried out at 200 to 350 ° C.

The thermosetting resin contained in the prepreg according to the present invention maintains stable physical properties at high temperatures. As a result, the prepreg according to the present invention has better heat resistance than other thermosetting resin prepregs.

1 is a flowchart showing a method of manufacturing a prepreg according to the present invention.

Hereinafter, an embodiment of the present invention will be described in detail. In the present specification, different embodiments are given the same or similar reference numerals, and the description thereof is replaced with the first explanation. As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

The present invention provides a method for producing a high temperature heat resistant prepreg. The thermosetting resin included in the prepreg of the present invention is made of polyimide (PI). Before describing the method for producing the prepreg according to the present invention, the polyimide will be described.

Polyimide (PI) is a polymer synthesized from an aromatic diamine and an aromatic dianhydride. It is an amorphous polymer with excellent insulation properties, heat resistance and weatherability. It is much lighter than metal and has high thermal mechanical properties and low thermal expansion. . Since polyimide is mainly developed for the purpose of high strength and high heat resistance, aromatic polyimide including a benzene ring is a predominant form. The substituents introduced into these aromatic rings are amide (-CONH-), fluorine (-CF3), ether (-O-), sulfone (-SO2-), and have different properties depending on the structure and substituent introduced . In general, the advantages of polyimide include high glass transition temperature, high heat resistance, insulation resistance, weather resistance, dimensional stability, and drawbacks are optical properties due to low workability and specific dark brown.

The polyimide is usually prepared by a two-step process. In the first step, the amine and anhydride are reacted with N, N-imethylacetamide (DMAc), N-methyl-1-2-pyrollidone (PAA), which is a precursor of polyimide, is synthesized through polymerization in an organic solvent such as -cresol. In the second step, the final polyimide is obtained through dehydration and ring-closing reaction of polyamic acid. The following four methods are typical polyimide synthesis methods.

1. Chemical imidization method ( Chemical imidization): pyridine (Pyridine) dehydration catalyst to the polyamic acid in solution, using a solvent easy to hydrate formation, such as acetic anhydride (Acetic anhydride) is terminating the imidation reaction in a solution state. This method uses an additional solvent such as pyridine and acetic anhydride in addition to the thermal imidization method, and terminates the imidization reaction in a solution state in which the molecular chain has fluidity. Therefore, in order to induce CTC (Charge Transfer Complex) Are arranged and have a disadvantage of showing a unique color.

2. The thermal imidation method (Thermal Imidization : This is the simplest method for thermally imidizing a polyamic acid solution by heating at 150 to 200 ° C. The disadvantage of this process is that when the amide-based solvent is used, the decomposition of the polymer can be induced by an amide exchange reaction.

3. Reprecipitation : A method of adding a polyamic acid solution to an excessive amount of a re-precipitation solvent to obtain a solid polyamic acid, which uses an ether system and an alcohol system, but mainly uses water. In this process, a polyamic acid having a high molecular weight can be obtained, but there is a disadvantage that some monomers are lost as compared with the initial amount of the polyamic acid.

4. Method isocyanate (Isocyanate): with a diamine in place of diisocyanate monomer, and a monomer mixture to remove the carbon dioxide gas through more than 120 ℃ heat treatment to manufacture a polyimide.

On the other hand, the reaction mechanism of the polyimide can be represented by the following formula (1).

Hereinafter, a method of manufacturing a prepreg according to the present invention will be described.

First, in the present invention, a step (S110) of preparing a mixture for preparing a prepreg (monomer mixture) is carried out by mixing an aromatic diamine, an aromatic dianhydride and an anhydride.

The aromatic diamine, the aromatic dianhydride and the anhydride may be mixed in a molar ratio of n + 1: n: 2, and n may be an integer of more than 0 and an integer of 10 or less.

Specifically, the amount of the anhydride, which is a crosslinking agent, is relatively increased to become brittle as the value of n is closer to 0, and the amount of the crosslinking agent decreases as the value of n increases. Thus, the glass transition temperature (TG) And low temperature stability is deteriorated. Therefore, in the present invention, the value of n is preferably 1 to 5.

On the other hand, the solvent of the mixture may be methanol.

Meanwhile, the aromatic diamine may be 3,4-oxydianiline (3,4-ODA), 4,4'-oxydianiline (4,4 ' -ODA), para-phenylenediamine (p-PDA), 4,4 '- (9,4-fluorenylidene) dianiline FDA), 1,3-bis (4-aminophenoxy) benzene, (TPE-R)).

The aromatic diamines may be represented by the following formulas (2) to (6).

3,4'-oxydianiline

4,4'-oxydianiline

Para-phenylenediamine

4,4 '- (9-fluorenylidene) dianiline

1,3-bis (4-aminophenoxy) benzene

The aromatic dianhydride may be 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3', 4,4'-benzophenonetetracarboxylic dianhydride , 4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3 ', 4,4'-oxydiphthalic dianhydride (3,3 ', 4,4'-oxydiphtalic dianhydride, (ODPA)), 4,4'-bisphenol A dianhydride (BPADA), pyrrollylricidianhydride (Pyromellitic Dianhydride, < RTI ID = 0.0 > (PMDA)). ≪ / RTI >

The aromatic dianhydrides may be represented by the following formulas (7) to (11).

3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride

3,3 ', 4,4'-biphenyltetracarboxylic dianhydride

3,3 ', 4,4'-oxydiphthalic dianhydride

4,4'-Bisphenol A dianhydride

Pyrrole Merrylic dianhydride

On the other hand, the anhydride may be Nadic anhydride (NA). The nadic anhydride may be represented by the following formula (12).

Meanwhile, the step of preparing the monomer mixture may further include esterifying the aromatic dianhydride and the anhydride, respectively.

Specifically, each of the dianhydride and nadic anhydride is mixed in a flask at a molar ratio of 1: 2m with methanol. Thereafter, a reflux condenser is attached to the flask, and heating is continued to reflux for 4 hours from the time when the powder is melted and the solution becomes transparent.

In this case, the value of m is an integer of 1 or more. When the value of m is less than 1, unreacted anhydride is present. When the value of m is higher, the nonvolatile content of the monomer mixture is lowered. desirable.

The carbonyl (C = O) peak of the anhydride at 1851 cm -1 disappears via Fourier transform infrared spectroscopy (FT-IR) while refluxing and the carbonyl peak of the ester at 1732 cm -1, 1712cm-1, which is the carbonyl peak of the carboxylic acid, is generated. When the anhydride peak disappears, the reflux is terminated.

Next, in the present invention, the monomer mixture is impregnated into a fiber sheet (S120).

The fibrous sheet can be made of quartz and, through a reduced pressure process, the monomer mixture can evenly spread over the fibrous sheet.

Finally, a step S130 of imidizing the monomer mixture impregnated in the fiber sheet proceeds.

The imidization reaction of the monomer mixture may be performed by a hot press at a temperature of 200 to 350 ° C. Further, the imidization reaction can be performed at a pressure of 250 psi.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. However, the scope and contents of the present invention are not construed to be limited or limited by the following Examples and Experimental Examples.

Example 1. Preparation of polyimide Cured goods  Produce

Pyrrol Merrylic dianhydride and nadic anhydride were each placed in a flask at a molar ratio of 1: 1 with methanol, and the mixture was heated with stirring with a reflux condenser. After refluxing, the solution was further refluxed for 4 hours from the time when the solution became transparent and reflux was terminated after confirming disappearance of the anhydride peak by FT-IR.

3,4-oxydianiline, esterified pyrrolylmethanilide dianhydride and nadic anhydride were added in a molar ratio of 2: 1: 2, methanol was added so that the nonvolatile content became 70%, and the mixture was stirred at room temperature for 2 hours to obtain a monomer A mixture was prepared.

The imidization of the monomer mixture was carried out in a convection oven at a rate of 2 ° C / minute from room temperature (25 ° C) to 200 ° C ± 10 ° C and maintained for 1 hour and then increased to 230 ° C ± 10 ° C at a rate of 1 ° C / And maintained for 30 minutes. Then, the temperature was raised to 320 ± 10 ° C at a heating rate of 1 ° C / minute and maintained for 1 hour.

Example 2. Preparation of polyimide Cured goods  Produce

A polyimide cured product was prepared in the same manner as in Example 1 except that 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride was used instead of pyrrole merrylic dianhydride.

Example 3. Polyimide Cured goods  Produce

3,3 ', 4,4 ' -benzophenone tetracarboxylic dianhydride was used instead of the pyrrole merrylic dianhydride and 3,4-oxydianiline, 3,3 ', 4,4'- Benzophenone tetracarboxylic dianhydride and nadic anhydride at a molar ratio of 4: 3: 2 to prepare a polyimide cured product.

Example 4. Polyimide Cured goods  Produce

3,3 ', 4,4 ' -benzophenone tetracarboxylic dianhydride was used instead of the pyrrole merrylic dianhydride and 3,4-oxydianiline, 3,3 ', 4,4'- A polyimide cured product was prepared in the same manner as in Example 1, except that the benzophenone tetracarboxylic dianhydride and nadic anhydride were used in a molar ratio of 5: 4: 2.

Example 5 Prepreg  Produce

The monomer mixture of Example 1 was poured into an inorganic fiber sheet, 10 sheets were laminated, packed in a vacuum pack, and reduced in pressure to impregnate the quartz fiber sheet with the monomer mixture. The mixture was heated to a temperature of 200 占 폚 / min from a room temperature (25 占 폚) to a hot press at a heating rate of 2 占 폚 / min and maintained at a heating rate of 1 占 폚 / To a temperature of 320 占 폚 to 10 占 폚 at a heating rate of 1 占 폚 / min and maintained for 1 hour to prepare a prepreg.

Example 6: Prepreg  Produce

A prepreg was prepared in the same manner as in Example 5 using the monomer mixture of Example 2.

Example 7: Prepreg  Produce

A prepreg was prepared in the same manner as in Example 5 using the monomer mixture of Example 3.

Example 8: Prepreg  Produce

A prepreg was prepared in the same manner as in Example 5 using the monomer mixture of Example 4.

Comparative Example 1

3,3 ', 4,4 ' -benzophenone tetracarboxylic dianhydride was used instead of the pyrrole merrylic dianhydride and 3,4-oxydianiline, 3,3 ', 4,4'- A polyimide cured product was prepared in the same manner as in Example 1, except that the molar ratio of benzophenone tetracarboxylic dianhydride to nadic anhydride was 3: 2: 2.

Comparative Example 2

Using the monomer mixture of Comparative Example 1, a prepreg was prepared in the same manner as in Example 5.

Experimental Example 1. Measurement of Viscosity and Specific Gravity of Monomer Mixture

Viscosity and specific gravity of the monomer mixture obtained in Examples 1 to 4 and Comparative Example 1 were measured at 25 占 폚.

Viscosity was measured with brookfiled viscometer LV type # 2 spindle and specific gravity was measured using 100 ml specific gravity cup.

Experimental Example 2: Hardened  Glass transition temperature and pyrolysis temperature measurement

The glass transition temperature (Tg) of the polyimide cured product was measured by dynamic mechanical analysis (DMA) using Q400 from TA intruments and the temperature at which the tangent delta (Tan Delta) Respectively.

The thermal decomposition temperature was determined by the temperature at which pyrolysis started using TGA2950 manufactured by TA intruments.

Experimental Example 3. Prepreg  Strength measurement

The mechanical strengths of the prepregs obtained in Examples 5 to 8 and Comparative Example 2 were measured using a universal testing machine (UTM). The tensile strength was ASTM D 638, the compressive strength was ASTM D 695, The strength was measured according to ASTM D790.

The physical properties of the polyimide cured product and the prepreg are shown in Table 1.

Example  One Example  2 Example  3 Example  4 Comparative Example  One Viscosity
( cPs, at  25 ° C) 204 248 256 241 252 importance( at  25 ° C) 1.142 1.131 1.122 1.132 1.124 Pyrolysis temperature 420 405 386 383 400 Hardened
Glass transition temperature (캜) 378 341 305 303 315 Example  5 Example  6 Example  7 Example  8 Comparative Example  2 The tensile strength( Mpa ) 650 690 620 605 630 Compressive strength ( Mpa ) 620 610 560 550 570 Flexural Strength ( Mpa ) 905 900 872 865 880

As shown in Table 1, the high temperature heat resistant prepreg prepared according to the present invention has a glass transition temperature of 378 ° C, which is 20% higher than that of Comparative Example 1. Thus, the prepreg having an improved glass transition temperature maintains stable properties at high temperatures, which results in superior heat resistance to epoxy resins as well as other polyimide resins.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

In addition, the above detailed description should not be construed in all aspects as limiting and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

Claims (8)

Aromatic diamine, aromatic dianhydride and anhydride are mixed in a molar ratio of n + 1: n: 2,
The aromatic diamine may be 3,4-oxydianiline, 4,4'-oxydianiline, p-Phenylene diamine, 4, 4 '- (9-Fluorenylidene) dianiline, 1,3-bis (4-aminophenoxy) benzene, ) < / RTI > benzene,
The aromatic dianhydride may be 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic dianhydride, Biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-oxydiphthalic dianhydride (3,3', 4,4'-biphenyltetracarboxylic dianhydride) a mixture for preparing a prepreg, wherein the prepolymer is a mixture of at least one selected from the group consisting of 4,4'-bisphenol dianhydride, 4,4'-Bisphenol A dianhydride and Pyro mellitic dianhydride. . Mixing in a solvent mixture for preparing a prepreg to prepare a monomer mixture;
Impregnating the fiber mixture with the monomer mixture; And
And imidizing the monomer mixture impregnated in the fiber sheet.
n is an integer greater than 0 and less than or equal to 10. 3. The method of claim 2,
The aromatic diamine may be 3,4-oxydianiline, 4,4'-oxydianiline, p-Phenylene diamine, 4, 4 '- (9-Fluorenylidene) dianiline, 1,3-bis (4-aminophenoxy) benzene, ) benzene). < / RTI > 3. The method of claim 2,
The aromatic dianhydride may be 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic dianhydride, Biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-oxydiphthalic dianhydride (3,3', 4,4'-biphenyltetracarboxylic dianhydride) wherein the high-temperature heat resistant prepreg is at least one selected from the group consisting of 4,4'-bisphenol dianhydride, 4,4'-Bisphenol A dianhydride and Pyro mellitic dianhydride. A method of manufacturing a leg. 3. The method of claim 2,
Wherein the anhydride is a nadic anhydride. ≪ RTI ID = 0.0 > 11. < / RTI > 3. The method of claim 2, wherein preparing the monomer mixture comprises:
Esterifying the aromatic dianhydride and the anhydride, respectively; And
And mixing the aromatic diamine, the esterified aromatic dianhydride, and the esterified anhydride in a solvent at a molar ratio of n + 1: n: 2 to the solvent. Gt;
n is an integer greater than 0 and less than or equal to 10. The method of claim 1, wherein the imidization reaction of the monomer mixture comprises:
Wherein the heat treatment is performed at 200 to 350 占 폚. A high-temperature heat-resistant prepreg produced by the production method according to any one of claims 2 to 7.

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