CS272342B1 - Means for carbon fibres surface treatment - Google Patents

Abstract

To allow carbon handling fibers, their protection against damage and securing adhesion to binders are applied surface layers on carbon fibers. Subject of the invention is a topical composition carbon fiber treatment that consists of of the following substances A, B, C, D, E, F, G where substance A is distilled or deionized water, substance B is organic, water soluble solvent - acetone or methyl ethyl ketone or ethylene glycol monomethyl ether or ethylene glycol monoethyl ether or methanol or ethyl alcohol, substances C, D, E are chemical epoxy resins formulas: HO - ΟΗ2ΟΗ2 - O CH. CH2 - O +. R - <o> - n ”CH2CT2OH” m where m = 30 to 120, G is alkyl polyglycol ether sulfate sodium, range of final concentrations of individual substances in the mixture is k ... basic medium - up to 100% wt. B ... 10 to 45 wt. C ... 0.05 to 4% " D ... 0.05 to 4 V E ... 0.01 to 2% " F ... 0.1 to 10% " G ... 0.01 to 1% " - O - taking ? ”3 - (0) -0- (0) -0-0¾. CH-, CH-CH, I CS 272 342 B1 - O - and for substance C is n = 0 or 1, substance D is n = 2 or 3, substance E is n = 5 to 10, substance F is polyethylene glycol

Description

Carbon fibers for plastic reinforcement are characterized by high mechanical properties - tensile strength and modulus of elasticity in tension. It follows from the structure of carbon fibers that the maximum mechanical properties are in a direction parallel to the axis of the fibers, perpendicular to this direction these properties are 10 to 30 times lower. Conventional carbon fibers have a diameter of 5 to 8 .mu.m and are easily damaged due to this fineness and lower transverse properties. To allow the fibers to be handled, to protect them from damage and, last but not least, to ensure adhesion to the binders, surface layers are applied to the carbon fibers. In the English literature, this modification is referred to as sizing. The initial coating of Union Carbide was based on a solution of polyvinyl alcohol. Gradually, various methods were developed and various substances were tested for this type of surface treatment. Substances forming protective coatings on carbon fibers must have film-forming properties, ie the ability to form a homogeneous continuous layer on all monofilaments of the fiber bundle, must bond monofilaments together so that the bundle acts practically as a whole into composite materials and must not reduce the resulting values of shear strength of composites.

Solutions of modified epoxy resins commonly used in laboratories in organic solvents have a disadvantage in the flammability of the mixture. This system is unsuitable for industrial production. The dispersion prepared by mixing epoxy resins and a nonionic emulsifier with very efficient mixing (DB 3436211) has a limited variability in the composition possibilities of the mixtures suitable for achieving different degrees of adhesion behavior of C-fibers with respect to processing technologies.

The use of oleic acid or oleyl alcohol esters according to U.S. Pat. No. 4,751,258 gives a mixture with a limited range of the polar component of the surface energy of the fiber, and thus lower adhesion for more polar binders. .

We propose a means for surface treatment of carbon fibers applied immediately after the preparation of fibers and their surface electrolytic treatment. The mixture is sufficiently emissive for carbon fibers with any range of electrolytic surface treatment, has sufficient film-forming properties, sufficiently connects the monofilaments in the cable and is permeable to conventional laminating resins. Its surface energy allows good adhesion in composite materials formed from an epoxy matrix and carbon fibers treated with this mixture.

Example 1

The carbon fiber cable prepared by thermal stabilization and carbonization of Wolpryl polyacrylonitrile fiber (3k, 1.1dtex) is, after carbonization and electrolytic surface treatment, led to a bath with water dispersion containing 20% acetone, 0.16 ® low molecular weight diane epoxy resin (n = 0 to 1 ), 0.18% of medium molecular weight diane epoxy resin (n = 2 to 3), 0.06% polyethylene glycol (n = 34) and 0.02% sodium alkyl polyglycol ether sulfate.

The fiber after drying was tested for wettability and mechanical properties in a composite plate. The cosine of the wetting angle for water was measured to be 0.64. The amount of extractables on the fiber (extraction with a Soxhlet apparatus in acetone) was found to be 1.1 microns. bismurea hardener was measured at 72 MPa.

Example 2

The carbon fiber prepared under the conditions of Example 1 was introduced into a bath containing an aqueous dispersion of 32 95 methyl ethyl ketone, 0.8% CHS Epoxy 15 (n = 0 to 1), 0.34 CHS Epoxy 1/33 (n = 2 to 3). , 0.07% CHS Epoxy 1/16 (n = 5 to 10), 0.7% polyethylene glycol (n = 34),

CS 272 342 Bl 2

0.1% sodium alkyl polyglycol ether sulfate.

The fiber after drying was tested and evaluated as suitable for processing into textile structures. It contained 1.7% of extractables in acetone. The cosine of the wetting angle for water was measured to be 0.81. The interlaminar shear strength of a unidirectionally arranged composite was found to be 74 MPa.

Example 3

The carbon fiber prepared under the conditions of Example 1 was passed to a bath containing an aqueous dispersion with 10% ethyl alcohol, 0.06% CHS Epoxy 15 (n = 0 to 1), 0.06% CHS Epoxy 1/33 (n = 2 to 3) , 0.02% CHS Epoxy 1/16 (n = 5 to 10), 0.1% polyethylene glycol (n = 34) and 0.01% sodium alkyl polyglycol ether sulfate.

After drying, the fiber was tested and evaluated as suitable for the preparation of prepregs. The content of acetone-extractable substances was 0.4%, the cosine of the water wetting angle was 0.61 and the interlaminar shear strength was 72 MPa.

Example 4

The carbon fiber prepared under the conditions of Example 1 was passed to a bath containing an aqueous dispersion with 45% methanol, 2.0% CHS Epoxy 15 (n = 0 to 1), 2.0% CHS Epoxy 1/33 (n = 2 to 3) , · - - - -,, .. _

0.05% CHS Epoxy 1/16 (n = 5 to 10), .......... .....

1.0% polyethylene glycol (n = 34) and 0.3% sodium alkyl polyglycol ether sulfate.

After drying, the fiber was evaluated as suitable for textile processing and for chopping into a material for reinforcing thermoplastics. The content of acetone-extractable substances was 3.4%, the cosine of the water wetting angle was 0.82, the interlaminar shear strength was 71 MPa.

Example 5

The carbon fiber prepared under the conditions of Example 1 was passed to a bath containing an aqueous dispersion with 20% ethylene glycol monomethyl ether, 0.16% CHS Epoxy 15 (n = 0 to 1), 0.18% CHS Epoxy 1/33 (n = 2 to 3) , 0.06% CHS Epoxy 1/16 (n = 5 to 10), 10.0% polyethylene glycol (n = 63) and 0.04% sodium alkyl polyglycol ether sulfate.

After drying, the fiber was tested and evaluated as suitable for textile processing and manual lamination. The content of acetone-extractable substances was 1.3% »cosine of the water wetting angle 0.96, interlaminar shear strength 71 MPa. .

Claims (2)

A composition for the surface treatment of carbon fibers, characterized in that it consists of the following substances A, B, 0, D, E, F, G, wherein substance A is distilled or deionized water, substance B is an organic, water-soluble solvent - acetone or methyl ethyl ketone or ethylene glycol monomethyl ether or ethylene glycol monoethyl ether or methyl alcohol or ethyl alcohol, substances C, D, E, are epoxy resins of the chemical formula: 3 OS 272 342 Bl whereas H means OH and for substance O is n ® 0 or 1, substance D is n «2 or 3, substance E is n« 5 to 10, substance P is polyethylene glycol HO 0H ₂ CH ₂ 0 · m CH ₂ CH ₂ OH < where m = 30 to 120, substance G is sodium alkyl polyglycol ether sulphate, the range of the resulting concentrations of the individual substances in And ... basic medium - addition to 100 95 wt. B ... 10 to 45 wt. Emes is O ... 0.05 to 4% D ... 0.05 to 4% E ... 0.01 to 2% F ... 0.1 to 10 95 · G ... 0.01 to 1% *