METHOD FOR PRODUCING A COMPRESSED-GAS CONTAINER

Abstract

The invention relates to a method for producing a compressed-gas container, particularly a compressed-gas container for transporting and for storing liquid gases or natural gas.

Claims

1. Method for producing a compressed-gas container which has a storage volume for a pressurised gas and a sleeve enclosing the storage volume, the sleeve comprising a liner in contact with the storage volume and, at least in regions, at least one second layer deposited on the liner, the method comprising the following method steps: a) providing i) a liner, ii) a curable epoxy resin matrix, and iii) reinforcing fibres, b) applying the curable epoxy resin matrix to the reinforcing fibres, the curable epoxy resin matrix having a temperature in the range of from 15 to 50° C., c) winding, laying or depositing the reinforcing fibres on the liner to form the second layer, d) curing the second layer at a temperature in the range of from 70 to 140° C., wherein the curable epoxy resin matrix has a viscosity in the range of from 200 to 1000 mPa.Math.s at a temperature in the range of from 40 to 50° C. over a period of at least 48 hours.

2. Method according to claim 1, wherein the curable epoxy resin matrix in method step b) has a temperature in the range of from 20 to 50° C.

3. Method according to claim 1, wherein the epoxy resin matrix is applied to the reinforcing fibres in such a way that the second layer has a weight ratio of reinforcing fibre to epoxy resin matrix in the range of from 50:50 to 80:20.

4. Method according to claim 1, wherein the epoxy resin matrix has a viscosity of from 300 to 900 mPa.Math.s at a temperature in the range of from 40 to 50° C.

5. Method according to claim 1, wherein the second layer is cured at a temperature in the range of from 70 to 120° C.

6. Method according to claim 1, wherein the epoxy resin matrix comprises: i) at least one epoxy resin having at least one epoxy group, ii) at least one reactive diluent from the group of glycidyl ethers, iii) at least one curing agent.

7. Method according to claim 1, wherein the epoxy resin matrix has an average EEW value in the range of from 100 to 250 g/eq before being cured.

8. Method according to claim 6, wherein the epoxy resin is selected from the group of bi-functional epoxy resins and/or in that the epoxy resin has an average EEW value of from 150 to 200 g/eq.

9. Method according to claim 7, wherein the reactive diluent is selected from the group of bi-functional glycidyl ethers and/or in that the glycidyl ether has an average EEW value of from 100 to 200 g/eq.

10. Method according to claim 1, wherein the reinforcing fibres are selected from the group consisting of carbon fibres, glass fibres, aramid fibres and basalt fibres.

11. Method according to claim 1, wherein the reinforcing fibres are provided in the form of filaments, threads, yarns, woven fabrics, braided fabrics or knitted fabrics.

12. Method according to claim 1, wherein the liner is a thermoplastics liner or a metal liner.

13. Method according to claim 1, wherein the curable epoxy resin matrix in method step b) has a temperature in the range of from 25 to 50° C.

14. Method according to claim 1, wherein the curable epoxy resin matrix in method step b) has a temperature in the range of from 30 to 50° C.

15. Method according to claim 1, wherein the curable epoxy resin matrix in method step b) has a temperature in the range of from 40 to 50° C.

16. Method according to claim 6, wherein the at least one curing agent is a liquid curing agent.

17. Method according to claim 16, wherein at least one curing agent is a cyanamide-containing curing agent.

18. Method according to claim 1, wherein the epoxy resin matrix has a viscosity of from 400 to 800 mPa.Math.s at a temperature in the range of from 40 to 50° C.

19. Method according to claim 1, wherein the epoxy resin matrix has a viscosity of from 400 to 700 mPa.Math.s at a temperature in the range of from 40 to 50° C.

Description

[0084] The present invention is explained in more detail below with reference to drawings and associated examples. In the drawings:

[0085] FIG. 1: is a simple schematic view of the fibre winding process for producing a compressed-gas container according to the present invention.

[0086] In FIG. 1, a winding system for producing a compressed-gas container is shown schematically. Starting from the spool stand system (1), the reinforcing fibres (2) are drawn via a reinforcing fibre guide (3) to the heatable impregnation bath (4) using an impregnation roller, resin scraper and reinforcing fibre guide. The tension of the reinforcing fibres through the impregnation bath (4) is generated by the rotation of the clamping device together with the liner (6), to which the reinforcing fibre bundles were fixed at the beginning of the process. As a result of the tension, the reinforcing fibres on the impregnation roller are wetted with the curable epoxy resin matrix, excess resin is wiped off using the resin scraper and a reinforcing fibre guide is pulled in the direction of the outlet head (5). The outlet head (5) controls the placement of the reinforcing fibres on the liner (6).

[0087] The following examples of the method were carried out using a system corresponding to this basic arrangement.

EXAMPLES

1) Curable Epoxy Resin Matrices

[0088] a) Raw Materials Used [0089] Component (A) Product name: DYHARD® RF2100 (AlzChem Trostberg GmbH) Modified, bi-functional bisphenol A epoxy resin (EEW=170-190 g/eq) (viscosity at 25° C.=4000-6000 mPa.Math.s) [0090] Component (B) Product name: DYHARD® Fluid 212 (AlzChem Trostberg GmbH) Cyanamide-based liquid curing agent (viscosity at 25° C.=80-160 mPa.Math.s) [0091] Component (C) Product name: EPON RESIN 828 (Hexion Inc.) Unmodified bisphenol A epoxy resin (EEW=185-192 g/eq) (viscosity at 25° C.=11-16 Pa.Math.s) [0092] Component (D) Product name: Jeffamine® T-403 (Huntsman Cooperation) Amine liquid curing agent (viscosity at 25° C.=72 mPa.Math.s) [0093] Component (E) Product name: Araldite® LY 1564 SP (Huntsman Cooperation) Formulated, bisphenol A-based epoxy resin (epoxy content=5.8-6.05 eq/kg) (viscosity at 25° C.=1200-1400 mPa.Math.s) [0094] Component (F) Product name: Aradur® 917 (Huntsman Cooperation) Anhydride liquid curing agent (viscosity at 25° C.=50-100 mPa.Math.s) [0095] Component (G) Product name: DMP-30™ (Sigma-Aldrich Chemie GmbH) Accelerator: 2,4,6-tris(dimethylaminomethyl)phenol [0096] Component (H) Product name: Araldite® LY 1556 SP (Huntsman Cooperation) Bisphenol A-based epoxy resin (epoxy content=5.30-5.45 eq/kg) (viscosity at 25° C.=10-12 Pa.Math.s) [0097] Component (I) Product name: 1-methylmidazole (Carl Roth GmbH & Co KG) Accelerator

[0098] b) Production of the Matrices

[0099] The liquid curing agents (components B, D, F) are added to the particular epoxy resins (components A, C, E, H) and, in the case of anhydride liquid curing agents (component F), the particular accelerators (component G or I) are added, and stirred until homogeneous. In each case, 100 g of the formulation is then removed for gel time measurements. At the same time, the isothermal viscosity is measured on the viscometer. A small proportion of the mixture is removed for the measurements on the DSC. For the winding process, the curable epoxy resin matrix produced in each case is heated to 40° C. and placed in the temperature-controlled impregnation bath. The fibre winding process begins when the temperature remains constant.

TABLE-US-00001 TABLE 1 Composition of curable epoxy resin matrix 1 according to the invention and comparison matrices 2, 3 and 4 Composition Matrix 1 Matrix 2 Matrix 3 Matrix 4 Component A 100 — — — Component B  10 — — — Component C — 100 — — Component D —  43 — — Component E — — 100 — Component F — —  98  90 Component G — —   3 — Component H — — — 100 Component I   1

[0100] c) Test Regulations for Checking the Material Properties

[0101] DSC:

[0102] Mettler Toledo DSC 1

[0103] Dynamic DSC:

[0104] A sample of the formulation is heated from 30 to 250° C. at a heating rate of 10 K/min. The exothermic reaction peak is evaluated by determining the onset temperature (T.sub.Onset), the temperature at the peak maximum (T.sub.Max) and the peak area as a measure of the heat of reaction released (Δ.sub.RH).

[0105] Isothermal DSC:

[0106] A sample of the formulation is kept constant at the specified temperature for the specified to time (isothermal curing of the formulation). The evaluation is carried out by determining the time of the peak maximum (as a measure for the start of the curing process) and of 90% conversion (as a measure for the end of the curing process) of the exothermic reaction peak.

[0107] Rheometer:

[0108] Anton Paar MCR 302 with CTD 450

[0109] Isothermal Viscosity:

[0110] The isothermal viscosity curve of a sample at 40° C. and 50° C. is determined on the Anton Paar viscometer MCR302 with the measuring system D-PP25 (1° measuring cone) at a measuring gap of 0.052 mm. When the preset temperature is reached in the measuring chamber of the viscometer, the measuring sample is applied to the measuring plate. The default setting for recording measuring points was set to continuous recording of 1 or 0.5 measuring points per minute.

[0111] It is measured in rotation at a shear rate of 5 l/s. The measuring cone is moved to the preset measuring gap height of 0.052 mm and the measurement is started.

[0112] After completion of the measurement, the measurement curve is evaluated using the data recording in the Rheoplus software, version 3.62, and the time taken to reach the viscosity of 1000 mPa.Math.s is taken from the data recording.

[0113] Gel Time Test:

[0114] Exactly 100 g of each formulation were produced in one go and then immediately placed in a drying cabinet at 40° C. and 50° C. The formulation was stirred and checked every hour. If the mixture could no longer be stirred homogeneously, the time was documented as gel time and the sample was classified as no longer liquid.

Example 1 (According to the Invention)

[0115] 10 parts by weight of component (B) are added to 100 parts by weight of component (A) and the mixture is stirred until homogeneous. In each case, 100 g of the formulation is then removed for gel time measurements. At the same time, the isothermal viscosity is measured on the viscometer. A small proportion of the mixture is removed for the measurements on the DSC.

TABLE-US-00002 TABLE 2 Epoxy resin compositions including test results (material parameters) Parameters Matrix 1 Matrix 2 Matrix 3 Matrix 4 Dynamic DSC-onset [° C.] 144 88 113 120 Dynamic DSC-peak [° C.] 152 132 138 152 Dynamic DSC-enthalpy [J/g] 243 548 319 420 Isothermal DSC at 100° C. 237 50 35 62 Time to 90% conversion [min] Gel time manually at 40° C. [h] >240 3.0 22 40 (100 g formulation) Gel time manually at 50° C. [h] 144 1.5 7.5 14 (100 g formulation) Isothermal viscosity at 40° C. [h] * 59 1.0 6.4 8.2 Isothermal viscosity at 50° C. [h] * 95 0.9 3.4 6.2 Starting viscosity at 40° C. [mPa*s] 585 443 150 204 Starting viscosity at 45° C. [mPa*s] 388 314 100 150 Starting viscosity at 50° C. [mPa*s] 242 202 90 106 * Pot life measurement via rheometer; time to reach viscosity of 1000 mPa*s.

[0116] Table 2 shows that, from the isothermal viscosity measurements and the determination of the initial viscosities from the isothermal measurement series of matrices 1-4, matrix 1 achieves high pot life values, at both 40° C. and 50° C., of 59 h at 40° C. and 95 h at 50° C. and thus has a viscosity range of from 200 to 1000 mPa.Math.s over 48 h. The manual gel time test of matrices 1-4 also shows that matrix 1 is liquid for well over 48 h at both temperatures and thus hardens from 144 h at 50° C. and over 240 h at 40° C. These comparisons therefore show a longer pot life and therefore also a higher latency of matrix 1 compared to the comparison matrices 2-4.

[0117] This means that the matrix system 1, due to the high latency, advantageously meets the requirements for compressed-gas cylinders, including those with larger volumes. Longer processing times with reduced cleaning stops and disposal residues are possible and the constant, low viscosity over the winding time can lead to constant wetting of the reinforcing fibres.

2) Examples of Liners—Manufacturer Certificates

[0118] An HDPE (PE-HD; high density polyethylene) liner having a capacity of 51 litres, a total length of 882 mm, a diameter of 314.5 mm and a weight of 8.9 kg (including boss parts) was used to for the experiment.

3) Examples of Reinforcing Fibres—Manufacturer Certificates

[0119] Carbon fibre: Mitsubishi Rayon MRC_37_800 WD_30 K Manufacturer: Mitsubishi Chemical Carbon Fiber and Composite, Inc.

4) Examples of Methods for Producing Compressed-Gas Containers

[0120] a) General Procedural Regulation—Possibly with Reference to the Drawings

[0121] Using the Composicad software, a winding structure of the carbon fibre was calculated, which is designed for a theoretical burst pressure of 460 bar. Our series of experiments is based on a cylinder designed for 200 bar. The standard requires a safety factor of 2.3 of the operating pressure for this type of pressure container, so therefore a minimum burst pressure of 460 bar. At the beginning, the HDPE liner is fastened in the clamping device to the winding machine at both ends, cleaned with acetone and activated using a Bunsen burner on the outside with a small flame. For the formulation, 100 parts of component A are stirred together with 10 parts of component B until homogeneous and heated to 40° C. Then the formulation is put into the temperature-controlled impregnation bath.

[0122] The impregnation bath is heated to 40° C. to set the optimum impregnation viscosity. The outside temperature during winding was 15.9° C. The scraper blade was set to a gap of 0.6 mm. The reinforcing fibres from the 8 spools are pulled through the bath to the liner and brought together on the component to form a strip approximately 2.7 cm wide. The winding process takes 35 minutes. The winding takes place axially and radially around the liner according to the calculations and adjustments in the program. In order to fix the end of the reinforcing fibre, it is placed under the penultimate winding as a loop and protruding fibres are cut off. The curing took place at 95° C. for 8 hours. The cylinder was hung horizontally in the furnace and rotated while being cured.

[0123] b) Test Regulations

[0124] Burst test according to ISO11439

[0125] Pressure cycle test according to ISO11439 and NGV02

[0126] c) Test Results

[0127] The cured cylinder has a weight of 17.70 kg. The diameter is 330 mm. A total of 5.494 kg of carbon fibre was used for the winding. Thus, the amount of formulation is 3.306 kg.

[0128] Burst test: Maximator Manometer analog 0-2500 bar (serial number 247298001), GS 4200 USB pressure transducer (serial number 510305)

TABLE-US-00003 TABLE 3 Achieved burst pressure and fibre tension and performances calculated therefrom Burst pressure [bar] 519 Achieved fibre tension [MPa] 3000 Container performance 1495.4 Laminate performance 3007.8

[00001]$\mathrm{Container}\mathrm{performance}:\frac{\left(\mathrm{burst}\mathrm{pressure}\times \mathrm{cylinder}\mathrm{volume}\right)}{\mathrm{Cured}\mathrm{cylinder}\mathrm{weight}}\times 1000$$\mathrm{Laminate}\mathrm{performance}:\frac{\left(\mathrm{burst}\mathrm{pressure}\times \mathrm{cylinder}\mathrm{volume}\right)}{\mathrm{Cured}\mathrm{laminate}\mathrm{weight}}\times 1000$

[0129] Pressure cycle test: Galiso Manometer analog 0-11,000 PSI (serial number 508130013)

TABLE-US-00004 TABLE 4 Results obtained from the pressure cycle test at room temperature. Number of cycles (cycles) 61432 Number of valid cycles (cycles) 61372 Max. temperature [° C.] 39.4 Average cycle rate (cycles/min) 9.1 Average pressure min. [bar] 2.7

[0130] After the test, the cylinder was inspected and showed no external defects. When cut in half, a small crack could only be found in the HDPE liner after 61432 cycles. The laminate remained undamaged.