RU2793760C1 - Dressed carbon fibre and polyetheretherketone composite material based on it - Google Patents

Abstract

FIELD: organic chemistry.

SUBSTANCE: dressed carbon fibres and polyetheretherketone composite materials based on them. Dressed carbon fibre of the composition is described: carbon fibre 99.4÷96.4 wt.%, 4,4'-diaminodiphenyl ketone (DADPK) 0.6÷3.6 wt.%, and 4,4'-diaminodiphenyl ketone is used as a dressing, deposited on carbon fibre from solutions with mass concentrations of 0.15 ÷ 0.9 wt.% in isopropanol, distillation of the solvent according to the regime: 20°С - 7 min, 45°С - 5 min, 55°С - 6 min, 65°С - 7 min, 75°С - 10 min, 83°С - 10 min. A polyetheretherketone composite material is also described, intended as a structural polymer material used in the manufacture of special products in additive technologies, containing a polymer matrix based on polyetheretherketone and dressed carbon fibre, and the dressed carbon fibre obtained by the above method is used, the quantitative ratio of components in the polyether ether ketone composite material corresponds to: polyetheretherketone 90 wt.%, dressed carbon fibre 10 wt.%.

EFFECT: improving the physical and mechanical properties of the polyether ether ketone composite material due to the introduction of 4,4'-diaminodiphenyl ketone, which increases the wettability of the filler and increases the boundary interactions between the filler and the polyetheretherketone matrix.

2 cl, 1 tbl, 6 ex

Description

The invention relates to the field of finished carbon fibers and polyetheretherketone composite materials based on them, and can be used for the production of structural products for special purposes in additive technology.

One of the ways to improve the performance of polyetheretherketone carbon fiber composites is to finish the carbon fiber surface, which makes it possible to modify the structure of the interfacial layer and increase intermolecular adhesive interactions at the polymer-filler interface.

Known polymer composite materials containing polyetherketones.

Patent EP 0224236 A2 is devoted to the creation of polymer compositions with improved chemical resistance and stable molding for injection molding, which contain polyether ketone (PEK), (not polyether ether ketone (PEEK)) aromatic polysulfone, and fillers, including carbon fiber.

EP 0316681 A2 also describes fibrous composites of polyethersulfone, polyetherketone (not polyetherketone) and carbon fiber. Both patents provide composites obtained from a mixture of two polymers - polyethersulfone, polytherketone, filled with fibers. They do not provide information on the finishing of carbon fibers to obtain PCM with enhanced mechanical properties.

In the patent RU 2278126, publ. 06/20/2006, bull. No. 17 shows the compositions used for crosslinking chains. This paper proposes to use a blend of amino-terminated polyetherketone (not PEEK) and anhydride-terminated polyethersulfone (PES) and copolyetherethersulfone (PEES) copolymers. The mixture is dissolved in a high-boiling solvent - N-methylpyrrolidone and carbon fibers are treated with it. The disadvantage of the solution is the use of a solvent with a high boiling point (203°C), which is difficult to remove from the composition, and its residues at high operating temperatures of the products will lead to the appearance of bubbles in the castings, and as a result, to a decrease in operational properties.

From the prior art, various types of sizing additives are known that are used in the creation of polymer composite materials. So, in the patent for invention RU 2057767, a polymer composite material is given, which includes a polysulfone polymer and carbon fibers. Carbon fibers contain on the surface as a sizing layer a copolymer consisting of units of methacrylic acid, diethylene glycol and benzosulfonic acid in a molar ratio of 49.5:49.5:1 to 49:49:2 in an amount of 0.52-5.0% of fiber mass in the following ratio of components, wt. %: carbon reinforcing fibers containing a copolymer, 25-75; polysulfone matrix rest. According to the inventors, the use of said copolymer as a sizing layer makes it possible to increase the interlaminar shear strength of polysulfone carbon plastics by a factor of 1.8-2.2. The main disadvantage of the proposed solution is the use of an aqueous medium for applying a mixture of monomers to a carbon tape. Since carbon fibers and tapes are hydrophobic, it is difficult to achieve a uniform distribution of an aqueous solution of a mixture of monomers. As a result of polymerization, incomplete conversion of monomers is also possible, which can lead to the formation and release of water at other stages of obtaining a polymer composite, which will lead to the formation of pores and a decrease in strength characteristics. The presence of benzenesulfonic acid in an aqueous medium will contribute to the accumulation of ions, which will worsen the dielectric properties of materials.

According to the patent of the Russian Federation No. 2201423, polymer compositions were obtained from a polymer binder (sizing) and fiberglass or carbon filler. First, a binder is obtained - an oligomer by the reaction of tetranitrile aromatic tetracarboxylic acid and aromatic bis-o-cyanamine at temperatures of 170-180°C. The binder is obtained in the form of a powder. The main disadvantage of this solution is the complexity of the process of obtaining a binder. With incomplete conversion of monomers during synthesis, low molecular weight by-products of the reaction may be released during the combination of the binder with the filler at an elevated temperature, resulting in the formation of voids in the composite material. This will lead to a deterioration in the strength characteristics of the material. In addition, powdered finishes may not cover the surface of the filler evenly enough.

Polyetheretherketone composites are known according to US patent No. 4049613. To increase the wettability of carbon fiber by a polymer matrix, the authors propose to keep the filler in hot nitric acid for three days, which is technologically and economically disadvantageous.

A known method of sizing carbon fiber according to RF patent No. 2054015 "Method of sizing carbon fiber for the production of polysulfone carbon fiber." According to the proposed method, the block copolymer is mixed with a solvent. A block copolymer consisting of units of bismethacryloyloxydiethylene glycol phthalate and bismethacryloyloxy triethylene glycol phthalate is used to impregnate the carbon filler, followed by drying to remove the solvent and polymerize the sizing film on the fiber, characterized in that the mixing is carried out in water with simultaneous exposure to ultrasonic radiation at a frequency of 15 to 44 kHz and duration exposure from 5 to 14 minutes. The disadvantages of this method are the use of aqueous solutions of block copolymers for wetting hydrophobic surfaces of carbon fiber and the need for further polymerization on the surface of the filler. The result may be uneven wetting of the filler, and, consequently, a decrease in the properties of the resulting carbon fiber.

The closest analogue is the method of sizing carbon fiber according to RF patent No. 2744893. "Polymeric carbon fiber composition and method for its production." The patent proposes to use hydroquinone as a sizing component of carbon fiber (carbon fiber, CF). The disadvantages of the proposed solution is the low stability of the coupling agent at elevated temperatures, which will lead to a decrease in the performance characteristics of the compositions.

The objective of the present invention is to develop new sized carbon fibers and polyester ether ketone composite materials based on them with higher values of physical and mechanical properties, based on a polyether ether ketone (PEEK) matrix polymer filled with sized carbon fiber (carbon fiber, CF).

This task is achieved in that the sized fibers are obtained by treating carbon fiber with a sizing agent - 4,4'-diaminodiphenyl ketone (DADPK), in isopropanol.

Matrix polyetheretherketone is an industrial polymer PEEK 450, which is a polycondensation product of 1,4-dioxybenzene and 4,4'-difluorodiphenylketone of the formula:

In this case, the following ratios of components in the filler are taken, wt. %:

carbon fiber 99.4 ÷ 96.4 DADFC 0.6 ÷ 3.6

The amount of finished carbon fiber in the composite material corresponds to 10 wt. %. Processing with such a sizing composition increases the wettability of the carbon fiber with polyetheretherketone, allows you to repeatedly carry out, if necessary, heat treatment of the resulting product without changing the properties of the sizing composition.

Finished carbon fibers according to the present invention are obtained by treating carbon fibers with a sizing component - a solution of 4,4'-diaminodiphenyl ketone in isopropanol, followed by distillation of the solvent. Composite materials are obtained by pre-mixing the polymer matrix - polyether ether ketone of the formula below and sized carbon fiber using a high-speed homogenizer Multi function disintegrator VLM-40B. Then the polymer mixture is extruded using a laboratory twin-screw extruder with three heating zones at processing temperatures of 200°C, 315°C, 355°C. We used carbon fiber brand RK-306 (IFI Technical Production), isopropanol brand "HCh" and matrix polyetheretherketone, which is an industrial polymer PEEK 450, which is a polycondensation product of 1,4-dioxibenzene and 4,4'-difluorobenzophenone of the formula:

Below are examples illustrating the method of obtaining sizing carbon fibers using sizing component.

Example 1. Preparation of finished HC with 0.6 wt. % DADFC.

In a three-necked reaction flask equipped with a stirrer, a nitrogen gas supply system and a direct condenser, 24.85 g (99.4 wt.%) of HC with a fiber length of 0.2 mm are placed and a solution obtained by dissolving 0.15 g (0. 6 wt.%) DADPA in 125 ml of isopropanol (0.15 wt.% solution). Include a stirrer, nitrogen supply, and incubated for 7 minutes at a temperature of 20°C. After that, the contents of the flask are heated and isopropanol is distilled off according to the regime: 45°C - 5 min; 55°C - 6 min; 65°C - 7 min; 75°С - 10 min, 83°С - 10 min.

The finished fiber is dried in an oven under vacuum at 79-80°C for 65 min.

Example 2. Preparation of finished HC with 1.2 wt. % DADFC.

In a three-necked reaction flask equipped with a stirrer, a nitrogen gas supply system and a direct condenser, 24.7 g (98.8 wt.%) of HC with a fiber length of 0.2 mm are placed and a solution obtained by dissolving 0.3 g (1. 2 wt.%) DADPA in 125 ml of isopropanol (0.3 wt.% solution). Include a stirrer, nitrogen supply, and incubated for 7 minutes at a temperature of 20°C. After that, the contents of the flask are heated and isopropanol is distilled off according to the regime: 45°C - 5 min; 55°C - 6 min; 65°C - 7 min; 75°С - 10 min, 83°С - 10 min.

The finished fiber is dried in an oven under vacuum at 79-80°C for 65 min.

Example 3. Preparation of finished HC with 1.8 wt. % DADFC.

In a three-necked reaction flask equipped with a stirrer, a nitrogen gas supply system and a direct condenser, 24.55 g (98.2 wt.%) of HC with a fiber length of 0.2 mm are placed and a solution obtained by dissolving 0.45 g (1. 8 wt.%) DADPA in 125 ml of isopropanol (0.45 wt.% solution). Include a stirrer, nitrogen supply, and incubated for 7 minutes at a temperature of 20°C. After that, the contents of the flask are heated and isopropanol is distilled off according to the regime: 45°C - 5 min; 55°C - 6 min; 65°C - 7 min; 75°С - 10 min, 83°С - 10 min.

The finished fiber is dried in an oven under vacuum at 79-80°C for 65 min.

Example 4. Preparation of finished HC with 2.4 wt. % DADFC.

24.4 g (97.6 wt.%) of HC with a fiber length of 0.2 mm is placed in a three-necked reaction flask equipped with a stirrer, a nitrogen gas supply system and a direct condenser, and a solution obtained by dissolving 0.6 g (2. 4 wt.%) DADPA in 125 ml of isopropanol (0.6 wt.% solution). Include a stirrer, nitrogen supply, and incubated for 7 minutes at a temperature of 20°C. After that, the contents of the flask are heated and isopropanol is distilled off according to the regime: 45°C - 5 min; 55°C - 6 min; 65°C - 7 min; 75°С - 10 min, 83°С - 10 min.

The finished fiber is dried in an oven under vacuum at 79-80°C for 65 min.

Example 5. Preparation of finished HC with 3.0 wt. % DADFC.

In a three-necked reaction flask equipped with a stirrer, a nitrogen gas supply system and a direct condenser, 24.25 g (97.0 wt.%) of HC with a fiber length of 0.2 mm is placed and a solution obtained by dissolving 0.75 g (3. 0 wt.%) DADPA in 125 ml of isopropanol (0.75 wt.% solution). Include a stirrer, nitrogen supply, and incubated for 7 minutes at a temperature of 20°C. After that, the contents of the flask are heated and isopropanol is distilled off according to the regime: 45°C - 5 min; 55°C - 6 min; 65°C - 7 min; 75°С - 10 min, 83°С - 10 min.

The finished fiber is dried in an oven under vacuum at 79-80°C for 65 min.

Example 6. Preparation of finished HC with 3.6 wt. % DADFC.

In a three-necked reaction flask equipped with a stirrer, a nitrogen gas supply system and a direct condenser, 24.1 g (96.4 wt.%) of HC with a fiber length of 0.2 mm is placed and a solution obtained by dissolving 0.9 g (3. 6 wt.%) DADPA in 125 ml of isopropanol (0.9 wt.% solution). Include a stirrer, nitrogen supply, and incubated for 7 minutes at a temperature of 20°C. After that, the contents of the flask are heated and isopropanol is distilled off according to the regime: 45°C - 5 min; 55°C - 6 min; 65°C - 7 min; 75°С - 10 min, 83°С - 10 min.

The finished fiber is dried in an oven under vacuum at 79-80°C for 65 min.

Composite materials containing 10 wt. % finished with 4,4'-diaminodiphenyl ketone carbon fibers.

Table 1 presents the compositions and properties of composite materials according to examples 1-6, treated with various amounts of 4,4'-diaminodiphenylketone.

Table 1
Properties of Polyether Ether Ketone Composite Materials Compound А _r , kJ/m²
11 J
s/n E _growth , GPa σ _rast ,
MPa σ _current ,
MPa PEEK 450 + 10% HC 0.2 mm 8.65 4.74 105 110.3 According to example 1 9.53 5.35 118.5 117.2 According to example 2 10.75 5.54 122.7 121.4 According to example 3 11.38 5.57 123.3 123.7 According to example 4 11.96 5.67 125.5 124.6 According to example 5 12.24 5.72 126.8 125.9 According to example 6 11.87 5.72 126.6 125.6

where And _p - notched impact strength, E rast - tensile modulus, σ rast - tensile strength, σ _tech - tensile yield strength.

As can be seen from the above data, polyetheretherketone composite materials with finished carbon fibers (Nos. 1-6) exhibit higher physical and mechanical properties compared to a material containing untreated carbon fiber.

The technical result of the invention is to improve the physical and mechanical properties of the created polyether ether ketone composite material by introducing a sizing agent - 4,4'-diaminodiphenyl ketone, which increases the wettability of the filler and increases the boundary interactions between the filler and the polyether ether ketone matrix.

Claims (5)

1. Finished carbon fiber composition, wt.%: carbon fiber 99.4÷96.4 4,4'-diaminodiphenyl ketone (DADPK) 0.6÷3.6 characterized in that 4,4'-diaminodiphenyl ketone is used as a coupling agent applied to carbon fiber from solutions with mass concentrations of 0.15÷0.9 wt.% in isopropanol, distillation of the solvent according to the regime: 20 ° C - 7 min, 45 ° С - 5 min, 55 °С - 6 min, 65 °С - 7 min, 75 °С - 10 min, 83 °С - 10 min. 2. Polyetheretherketone composite material intended as a structural polymeric material used in the manufacture of special products in additive technologies, containing a polymer matrix based on polyetheretherketone and finished carbon fiber, characterized in that it uses a finished carbon fiber obtained by the method according to claim 1, and the quantitative ratio of the components in the polyetheretherketone composite material corresponds, wt.%: polyetheretherketone 90 finished carbon fiber 10