1C system, products to be manufactured from the system, and a method for manufacturing semifinished, fiber-reinforced products and components with the 1C system

Abstract

The invention relates to a 1C system and a method for manufacturing semifinished products (prepregs) and components with the 1C system. The problem is solved by a 1C system comprised of an epoxy resin and a secondary amine; the secondary amine is imidazole, an imidazole derivative or a complex of the general formula MeL.sub.4X.sub.2, wherein Me is a bivalent metal cation selected from copper, cobalt, nickel and zinc, L is a ligand selected from imidazole and an imidazole derivative, and X is an anion selected from fluoride, chloride, bromide, iodide and nitrate. Furthermore, the invention includes a method for manufacturing impregnated semifinished products for the production of duroplastic fiber-reinforced components using a 1C system.

Claims

1. 1C system comprised of an epoxy resin and a secondary amine as a curing agent, characterized in that the secondary amine is a complex of the general formula MeL4X2, wherein Me is a bivalent metal cation selected from copper, cobalt, nickel and zinc, L is a ligand selected from imidazole and an imidazole derivative, and X is an anion selected from fluoride, chloride, bromide, iodide and nitrate.

2. 1C system according to claim 1, characterized in that the epoxy resin is based on bisphenol A.

3. 1C system according to claim 1, characterized in that the epoxy resin has an epoxy value of 0.05 to 0.28 mol/100 g.

4. 1C system according to claim 1, characterized in that the epoxy resin has a softening temperature in the range of 50 to 130 C.

5. 1C system according to claim 1, characterized in that the 1C system includes 86 to 99% by weight of the epoxy resin, measured with regard to the total mass of the 1C system.

6. 1C system according to claim 1, characterized in that the imidazole derivative is an imidazole with an alkyl substituent in at least one of the positions 2, 4 or 5 of the imidazole molecule.

7. 1C system according to claim 1, characterized in that the imidazole or the imidazole derivative is a complex.

8. 1C system according to claim 1, characterized in that the 1C system includes 1 to 14% by weight of the imidazole or imidazole derivative, measured with regard to the total mass of the 1C system.

9. 1C system according to claim 1, characterized in that the 1C system has a cross-linking temperature of over 100 C.

10. 1C system according to claim 1, characterized in that the IC system is a matrix material for a fiber-reinforced component.

11. Method for manufacturing impregnated semifinished products for the production of duroplastic fiber-reinforced components using a 1C system according to claim 1 characterized by the following process steps: a) Application of the powdered 1C system according to claim 1 to a textile reinforcement structure; b) Melting the 1C system via an increase in temperature up to a temperature below the cross-linking temperature; c) Cooling of the impregnated semifinished product.

12. Method according to claim 11, characterized in that the powdered 1C system in step a) is applied via spraying or screening.

13. Method according to claim 11, characterized in that the 1C system is applied over the entire area or on a local basis and either directly onto the reinforcement structure or onto the mold before the insertion of the reinforcement structure.

14. Method according to claim 11, characterized in that the reinforcement structure is made up of several layers and the 1C system is also applied between the layers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is to be explained in more detail, without limiting it, with the aid of the descriptions and examples that are provided. The figures show the following here:

(2) FIG. 1 shows the layer-type structure of a prepreg as per the invention,

(3) FIG. 2 shows the prepreg according to FIG. 1 after the impregnation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(4) a) Production of a 1C Epoxy Resin

Example 1

(5) To manufacture a 1C system as per the invention, 98% by weight of BPA epoxy resin with an epoxy value of 0.26 mol/100 g and a softening temperature of 55 C. is mixed in a double-cone mixer for 20 min. with 2% by weight of 2-methylimidazole at room temperature.

(6) A quantity of the 10 system as per the invention was prepared by mixing 98 parts by weight of BPA epoxy resin (E2) having an epoxy value of 0.26 mol/100 g and a softening temperature of 55 C. with 2 parts by weight of 2-methylimidazole (2MI) at room temperature for 20 minutes in a double-cone mixer. The mixture that was prepared was ascertained in a DSC analysis by determining the enthalpy of the cross-linking process, which is approx. 180 J/g, and the maximum cross-linking temperature, which is approx. 85 C.

Example 2

(7) A quantity of the 1C system as per the invention was prepared by mixing 92 parts by weight of BPA epoxy resin (E1) having an epoxy value of 0.20 mol/100 g and a softening temperature of 63 C. with 8 parts by weight of a latent curing agent based on 2-methylimidazole with a general formula of (Cu(2MI).sub.4Cl.sub.2) at a temperature of 80 C. for 10 minutes with an anchor agitator. The 1C system that was produced was formed into a band shape, cooled down to 25 C. and ground down in blade granulator.

(8) The mixture that was prepared was ascertained in a DSC analysis by determining the enthalpy of the cross-linking process, which is approx. 260 J/g, and the maximum cross-linking temperature, which is approx. 150 C.

(9) b) Production of a Prepreg

Example 1

(10) In accordance with a first example of the implementation of the method for manufacturing products pre-impregnated with the 1C system, called prepregs, the reinforcement layer 2, comprising a fabric made of carbon fibers with a weight of 410 g/m.sup.2, is prepared in terms of its dimensions in the first step of the process. The upper surface of the reinforcement layer 2 is coated with a pulverized 1C system; the pulverized 1C system is applied as layer 3 with a uniform density of 170 g/m.sup.2 in the process.

(11) Layers of the reinforcement and of the 1C system that are prepared in this way are accommodated in a press most economically in the form of a sheet of silicone paper 1 on a continuous separation layer made up of non-impregnable and non-adhesive material; after that, the upper layer is laid on it in the form of a second sheet of silicone paper 4.

(12) The compulsory arrangement of the individual prepreg layers is shown pictorially in FIG. 1, in which a cross-section of the prepreg can be seen; the plane is perpendicular to all of the layers.

(13) A stack that is prepared in this way is accommodated in a press with heating plates and heated to 80 C. It is kept at this temperature for 10 minutes and a pressure of 2 bar is simultaneously exerted on the stack in the process.

(14) The prepreg cools down on its own after the completion of the heat and pressure phase. The arrangement of the individual layers after the cooling is shown in a cross-section in FIG. 2.

(15) As shown in FIG. 2 and as can be concluded from the drawing, the 1C system layer 3 from FIG. 1 is converted from a solid state into a semi-liquid state while being kept hot and while being subjected to pressure on the prepreg, and it penetrates and soaks the reinforcement layer 2. In the process, the outer protective layers 3a and 3b, which can be seen in FIG. 2, form on both sides from the 1C system.

(16) The material for prepregs that is created in this way has the characteristics shown in Table 1.

(17) TABLE-US-00001 TABLE 1 Change in reactivity Max. Storage Cross-linking capability (Enthalpy cross-linking time enthalpy difference) temperature [Month] [J/g] [%] [ C.] 0 120.6 88 1 118.3 1.9 90 2 117.8 2.3 91 3 117.2 2.8 91 6 114.9 4.7 93

Example 2

(18) In accordance with a second example of the implementation of the method for manufacturing prepregs, a reinforcement layer is prepared in the first step of this example that is a fabric band made of basalt fibers with a weight of 210 g/m.sup.2. The upper surface of the reinforcement layer is coated with a pulverized 1C system; the pulverized 1C system is applied as layer with a uniform density of 140 g/m2 in the process.

(19) Layers of the reinforcement and of the 1C system that are prepared in that way are accommodated between two band-shaped layers made of silicone paper; after that, the stack is put into a calender that has been heated up to 90 C. The conveyor speed of the bands is 0.5 m/minute in the calenders.

(20) The band-shaped prepreg that is produced cools down on its own and is then wound onto rollers.

(21) The characteristics of the prepreg that was manufactured in accordance with the second example of the method as per the invention and that were investigated within 12 months of storage time are shown in Table 2.

(22) TABLE-US-00002 TABLE 2 Change in reactivity Max. Storage Cross-linking capability (Enthalpy cross-linking time enthalpy difference) temperature [Month] [J/g] [%] [ C.] 0 200.2 162 1 199.3 0.5 162 2 198.7 0.7 163 3 198.1 1.0 163 6 197.3 1.4 164 12 192.8 4.0 167

Example 3

(23) The following example describes the production of a tub made of a prepreg. The prepreg is comprised of a glass cloth with a plain weave. The layer thickness is approx. 0.35 mm. Six layers are positioned one over the other in a mold and pre-heated in an infrared heater at a temperature of approx. 110 C. with a holding time of 30 s. After that, the layer stack is put into a mold tempered to 120 C., reshaped by closing the mold and consolidated at a pressure of 40 bar over a time period of 10 min.

(24) After cooling, the tub that is now consolidated is removed from the mold and the edges are reworked if necessary.

Example 4

(25) The following example describes the production of the tub from Example 3 using carbon-fiber fabric and the 1C system as per the invention.

(26) The starting point is a carbon-fiber fabric in a twill weave (2/2) with a layer thickness of 0.56 mm and a weight per unit area of 400 g/m.sup.2. The individual cut sections for the fiber layers have a size of 320210 mm.

(27) First, a quantity of approx. 15 g of the powdered 1C system are applied to a layer of the fabric and distributed with a spatula. A further layer is then put on this layer and 15 g of the 1C system are once again distributed on it. This is repeated until four layers are positioned one over the other; 15 g of the 1C system are applied between each of the layers.

(28) 25 g of the 1C system are likewise distributed with a spatula on top of the last (fourth) layer. Before the stack is put into the mold, 25 g of the 1C system are likewise distributed over the surface in the mold and the stack is then placed on top of it. After that, the mold, tempered to 120 C., is closed. The hardening takes place at a pressure of 40 bar over a time period of 10 min. After cooling, the workpiece is removed and reworked if necessary.

LIST OF REFERENCE NUMERALS

(29) 1 Silicone paper 2 Reinforcement layer/reinforcement structure 3 1C system 3a Outer protective layer of the 1C system 3b Outer protective layer of the 1C system 4 Silicone paper