RU2769396C1 - Method of producing finishing agent, finished polyester-ether-ketone composite and method for production thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be used to produce polymer composite materials. Method of obtaining a finishing agent for producing polyetheretherketone carbon-fiber polymer composite materials involves extraction of soluble amorphous polyetheretherketone from industrial polyetheretherketone PEEK 450. Extraction is carried out while boiling in dichloroacetic acid for 30–120 minutes. Invention also discloses a finished polyester-ether-ketone composite and a method for production thereof.

EFFECT: improvement of impact strength, modulus of elasticity, breaking stress and tensile yield strength of polymer composite materials.

3 cl, 1 tbl, 9 ex

Description

The development of many advanced technologies, such as additive technologies, requires the use of composite materials with improved thermal and physical and mechanical characteristics. The low strength properties of many polymer composites (PC) are due to low interboundary interactions at the filler-polymer interface. It is possible to increase the adhesion between the polymer matrix and the filler using various coupling agents.

Known polymer composite materials (PCM) 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 polyetherketone, (non-polyetherketone) aromatic polysulfone, and fillers, including carbon fiber.

EP 0316681 A2 also describes fibrous composites of polyethersulfone, polyetherketone (not polyetherketone) and carbon fiber. Both patents present 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 performance properties.

It was not possible to find works devoted to composites consisting of "pure" polyether ether ketones and finished carbon fibers (CF) in the literature.

From the prior art, various types of sizing additives used in the creation of polymer composite materials are known. 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.

Known polyesterimide composites according to US patent No. 4049613. To increase the wettability of carbon fiber polymer matrix, the authors propose to withstand the filler in hot nitric acid for three days, which is technologically and economically unfavorable.

The closest analogue is the method of sizing carbon fiber according to the patent of the Russian Federation 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.

In the work of Mikhailin Yu.A. "Heat-resistant polymers and polymeric materials", St. Petersburg, ed. "Profession", 2006, p. 139. Victrex PEEK polyether ether ketones (derived from hydroquinone and 4,4'-difluorodiphenyl ketone) may have a crystallinity of 25-75%, depending on the heat treatment conditions. Therefore, the content of the amorphous phase can be 75-25%.

The objective of the present invention is to obtain a polymer composite material with higher values of physical and mechanical properties based on a matrix polymer of polyetheretherketone (PEEK) reinforced with sized carbon fiber (CF) and to develop a method for its production.

The task is achieved by the fact that composite materials are obtained from the matrix industrial polyetheretherketone PEEK 450, which is a polycondensation product of 1,4-dioxibenzene (hydroquinone, HQN) and 4,4'-difluorodiphenyl ketone of the formula:

reinforced with finished carbon fibers. Amorphous polyether ether ketone (APEEK) soluble in 2,2-dichloroacetic acid (DCCA) isolated from the above polyether ether ketone PEEK 450 is used as a carbon fiber sizing.

In this case, the following ratios (wt. %) of the components in the filler (HC + APEEK) are taken:

carbon fiber 95 ÷ 99; APEEK 5 ÷ 1;

The amount of finished carbon fiber in the composite material corresponds to 10 wt. %. Such treatment of carbon fiber with a sizing composition increases the wettability of the filler with oligoetheretherketone, makes it possible to repeatedly heat treat the resulting product, if necessary, without changing the properties of the sizing agent.

The carbon filler is coated with a sizing composition by treatment in 2,2-dichloroacetic acid, then dried to constant weight.

Composite materials of the present invention are obtained by pre-mixing the polymer matrix and sized CF 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. The carbon fiber used was RK-306 (IFI Technical Production) and industrial grade PEEK 450, with a reduced viscosity of 0.32 dl/g, measured from a 1% solution in concentrated sulfuric acid.

Below are examples illustrating the method of obtaining finished carbon fibers, with the ranges: 30-120 minutes, with a yield of 25.3-29.3% of the product and with a mass fraction of 0.16-0.79%.

Example 1Isolation of soluble in 2,2-dichloroacetic acid APEEK from PEEK 450

In a two-necked round-bottom flask equipped with a reflux condenser, a mechanical stirrer and a heater, 44 g of polyetheretherketone PEEK 450 are placed and 250 ml of DCUK are added. Turn on the stirrer, heater, and within 30 min (heating rate - 5-6°C/min) bring the temperature of the reaction flask to a boil with DCA. Maintained at the boil for 30 minutes. The contents of the flask are cooled to room temperature, filtered through a Schott filter with a Bunsen flask. The filtrate is a solution of the amorphous phase of PEEK in DCCA. The insoluble part is the crystalline phase of PEEK with the remains of the amorphous phase.

The filtrate is poured into distilled water, precipitated, and the white precipitate of amorphous PEEK is washed until the wash water is neutral.

Polyetheretherketone is dried in an oven according to the regime: 50°C - 30 min.; 70°С - 30 min.; 85°С - 30 min.; 100°C - 30 min. Then, drying is carried out under vacuum at 120-130°C for 2 hours. 10.1 g (25.3%) of an amorphous polyetheretherketone soluble in DCCA is obtained.

Example 2

The process is carried out as in example 1, only kept at a boil for 60 minutes. 12.2 g (27.7%) of amorphous polyetheretherketone soluble in DCCA are obtained.

Example 3

The process is carried out according to example 1, only kept at a boil for 90 minutes. 12.5 g (28.4%) of amorphous polyetheretherketone soluble in DCCA are obtained.

Example 4

The process is carried out according to example 1, only kept at a boil for 120 minutes. 12.9 g (29.3%) of an amorphous polyether ether ketone soluble in DCCA are obtained.

Example 5Finishing discrete carbon fiber.

24.75 g (99 wt. %) of discrete HC with a fiber length of 0.2 mm is placed in a three-necked round-bottom flask equipped with a reflux condenser, a device for supplying gaseous nitrogen, a heater and a mechanical stirrer and a solution obtained by dissolving 0.25 g (1.0 wt.%) APEEK, obtained according to example 1, in 100 ml DCUK (0.16% solution). Turn on the stirrer, nitrogen supply and stir for 30 minutes at room temperature. Next, the contents of the flask are heated according to the regime: 60°C - 30 min.; 80°C - 30 min; 100°C - 30 min; 110°С - 30 min. The contents of the flask are cooled to room temperature, filtered through a Schott filter with a Bunsen flask. The filtrate is removed for regeneration of DHUK, the residue on the filter is washed with distilled water until the wash water is neutral.

The dressed fiber is dried in an oven under vacuum at 130-135°C for 2 hours.

Example 6. According to example 5, only load into the flask: 24.5 g (98 wt.%) HC and pour in a solution obtained by dissolving 0.5 g (2.0 wt.%) APEEK in 100 ml DCUA (0.32 % solution).

Example 7. According to example 5, only load into the flask: 24.25 g (97 wt.%) HC and pour in a solution obtained by dissolving 0.75 g (3.0 wt.%) APEEK in 100 ml DCUA (0.48 % solution).

Example 8. According to example 5, only load into the flask: 24.0 g (96 wt.%) HC and pour in a solution obtained by dissolving 1.0 g (4.0 wt.%) APEEK in 100 ml DCUA (0.63 % solution).

Example 9. According to example 5, only load into the flask: 23.75 g (95 wt.%) HC and pour in a solution obtained by dissolving 1.25 g (5.0 wt.%) APEEK in 100 ml DCUA (0.79 % solution).

From finished hydrocarbons (according to examples 5-9) and PEEK (PEEK 450) obtained PCM containing 10 wt. % HC (Table 1).

Table 1

Properties of Polyether Ether Ketone Composites Based on PEEK 450 Containing APEEK Finished Carbon Fibers

Compound А _r , kJ/m²
11 J s/n
E _growth, GPa σ _grow,
MPa σ _current,
MPa PEEK 450 + 10% HC 0.2 mm 8.65 4.74 105 110.3 According to example 5 8.86 4.81 107.4 110.8 According to example 6 9.78 4.92 110.7 111.4 According to example 7 eleven 5.07 112.5 112 According to example 8 eleven 5.03 112.1 112 According to example 9 eleven 5.01 111.8 111.5

where, And _p - impact strength, E _rast - tensile modulus; σ _rast - tensile strength, σ _flow - tensile yield strength.

The data in the table show that composite materials containing sized HC (examples No. 5-9) have higher values of impact strength, tensile moduli, breaking tensile stress, tensile yield strength compared to an untreated sample (first line ).

The technical result of the invention is to increase the impact strength, tensile modulus of elasticity, tensile stress at failure, tensile yield strength of the created polyetheretherketone carbon fiber composite by introducing a sizing component - amorphous polyetheretherketone soluble in 2,2-dichloroacetic acid, isolated industrial polyetheretherketone PEEK 450, which increases the wettability of the carbon fiber and increases the intermolecular interactions between the filler and the polyether ether ketone matrix.

Claims (6)

1. A method for producing a coupling agent for creating polyether ether ketone carbon fiber polymer composite materials (PCM), characterized in that soluble amorphous poly ether ether ketone is isolated from industrial poly ether ether ketone PEEK 450 by boiling in dichloroacetic acid for 30-120 minutes with a yield of 25.3-29.3 %. 2. Finished polyether ether ketone composite intended for use as a superstructural polymeric material, characterized in that polyether ether ketone based on 1,4-dioxybenzene and 4,4'-difluorodiphenyl ketone is used as a polymer matrix, and a composition including components ( wt.%): carbon fiber 95 - 99 sizing obtained by the method according to claim 1, which is amorphous polyetheretherketone (APEEK), 5-1, moreover, the sized polyether ether ketone composite contains 10 wt.% filler. 3. A method for producing a sizing polyether ether ketone composite according to claim 2, intended as a superstructural polymeric material, including sizing carbon fiber by applying a sizing component from a solution followed by drying, characterized in that the sizing composition is applied from a solution with a mass fraction of 0.16-0 ,79% in dichloroacetic acid and carry out a stepwise rise in temperature according to the regime: 60 ° C - 30 min; 80°C - 30 min; 100°C - 30 min; 110°С - 30 min.