POLYURETHANE-BASED POLYMER MATERIAL HAVING EXCELLENT RESISTANCE TO HEAT DISTORTION AND ELONGATION AT TEAR

Abstract

The present disclosure relates to processes for the production of a polyurethane material, where (a) di- and/or polyisocyanates, (b) compounds which have hydrogen atoms reactive toward isocyanate groups and which do not include compounds having carbon-carbon double bonds, (c) compounds including at least one carbon-carbon double bond, (d) optionally catalyst that accelerates the urethane reaction, and (e) optionally other auxiliaries and additives are mixed to give a reaction mixture and the mixture is hardened at temperatures above 120 C. The present disclosure further relates to a polyurethane material obtainable by this process, and also to the use of the polyurethane material, in particular of a polyurethane fiber-composite material as structural components.

Claims

1. A process for the production of a polyurethane material with a heat-deflection temperature of at least 130 C. in three-point bending with 0.45 MPa outer fiber stress in accordance with DIN EN ISO 75, the process comprising: mixing components comprising: a. di- and/or polyisocyanates, b. compounds having hydrogen atoms reactive toward isocyanate groups, where the compounds having hydrogen atoms reactive toward isocyanate groups comprise no compounds having carbon-carbon double bonds, c. compounds comprising at least one carbon-carbon double bond, d. optionally a catalyst that accelerates a urethane reaction, and e. optionally other auxiliaries and additives, to give a reaction mixture, and hardening the reaction mixture at temperatures above 120 C., where: the compounds b) having hydrogen atoms reactive toward isocyanate groups have, per molecule, an average of at least 1.5 hydrogen groups reactive toward isocyanate and the compounds (c) comprising at least one carbon-carbon double bond comprise compounds (c1) comprising at least one carbon-carbon double bond and at least one group selected from groups reactive toward isocyanate and isocyanate groups and/or compounds (c2) comprising at least two carbon-carbon double bonds, and where the reaction mixture has been stabilized by addition of a free-radical inhibitor such that when the components are mixed at room temperature and the reaction mixture is injected into a metal mold with dimensions of 20 cm30 cm0.4 cm controlled to a temperature of 80 C. and is demolded after 60 minutes and cooled to room temperature, the heat-deflection temperature of the polyurethane material in three-point bending with 0.45 MPa outer fiber stress in accordance with DIN EN ISO 75 is at least 25 C. lower than the heat-deflection temperature of an identically produced polyurethane material which is heat-conditioned for a further 120 minutes at 150 C. in an oven after the production process and then is cooled to room temperature.

2. The process according to claim 1, wherein an impact resistance of the polyurethane material in accordance with DIN EN ISO 179-1/1fU is above 25 kJ/m.sup.2.

3. The process according to claim 1, wherein an equivalence ratio of isocyanate groups of the di- and/or polyisocyanates (a) to the hydrogen atoms reactive toward isocyanate is 0.7 to 1.4.

4. The process according to claim 1, wherein a proportion of an entirety of the compounds (c1) and (c2), based on a total quantity of compounds (c), is 5 to 100 mol %.

5. The process according to claim 1, wherein a molar mass of the compound (c) is below 1000 g/mol.

6. The process according to claim 1, wherein the compounds (c1) and (c2) have, based on the carbon-carbon double bonds, 60 to 100% of terminal carbon-carbon double bonds.

7. The process according to claim 1, wherein the di- and/or polyisocyanates (a) comprise at least 50 mol % of isocyanates with functionality of 2.

8. The process according to claim 1, wherein the di- and/or polyisocyanates (a) comprise 2,4-MDI, 4,4-MDI or a mixture of these components, optionally also with MDI homologs having a larger number of rings.

9. The process according to claim 1, wherein the reaction mixture comprises 0.001 to 1.0% by weight of the free-radical inhibitor.

10. The process according to claim 1, wherein the reaction mixture further comprises basic catalysts.

11. The process according to claim 1, wherein a proportion of the compounds (c) having carbon-carbon double bond, based on a total weight of components (a) to (e), is 10 to 70% by weight.

12. The process according to claim 1, wherein the compounds (b) having hydrogen atoms reactive toward isocyanate groups comprising no compounds having carbon-carbon double bonds, comprise higher-molecular-weight compounds having hydrogen atoms reactive toward isocyanate and molar mass of 300 g/mol and above, and the higher-molecular-weight compounds having hydrogen atoms reactive toward isocyanate comprise at least one hydroxy-functional compound having hydrophobic groups.

13. The process according to claim 1, wherein a reaction of the reaction mixture is conducted in a first stage for at least 10 minutes at temperatures below 120 C. and then the reaction mixture is hardened at temperatures above 150 C.

14. The process according to claim 1, wherein the polyurethane material is a polyurethane fiber-composite material, where the reaction mixture is used to wet a fiber material and then the reaction mixture is hardened to give the polyurethane fiber-composite material.

15. A polyurethane material obtainable by a process according to claim 1.

Description

[0062] The invention is illustrated below with the aid of examples.

[0063] <img class=EMIRef id=598068494-imgf000017_0001/>

Table 1: Manufacture of Thermally Stable Resins

[0064] The starting materials (data in all tables in percent by weight. Usual batch size: 300 g polyol component) are mixed at room temperature, then adding the isocyanate and mixing for 60 s in a speed mixer (FA Hauschild), then pouring the reaction mixture into a 20300.4 cm metal mold or 20300.2 cm, wipe off the excess resin with a doctor blade and harden at 80 C. for 1 h, then for 2 h at 120 C. and 2 h at 170 C. The material is then stored at room temperature for 1 week

[0065] Test specimen milled. The results in Table 1 show that, in the absence of radical starters, a significantly higher heat resistance is found in the examples according to the invention. The heat resistance (three-point bending at 0.45 MPa edge fiber tension according to DIN EN ISO 75) of over 150 C. is remarkable for polyurethane materials. According to this example, the production of fiber-reinforced pipes is possible in particular, for example in the fiber winding process

Comparative Example

[0066] 2:

[0067] There will be 99.5 TI. TMPTA and 0.5 TI. Radical starter 1 mixed at room temperature and at 80 C. for 10 min. hardened. An inhomogeneous, brittle polymer with an irregular surface is obtained, from which no test specimens can be removed. The Tg (determined by DSC) is 122 C. The person skilled in the art is aware that the Tg of a polymer is usually above the heat distortion temperature. The comparative example 2 with radically produced homopolymer of the olefin thus has a significantly lower heat resistance than the examples according to the invention.

Table 2

[0068] <img class=EMIRef id=598068494-imgf000018_0001/>

Table 2

[0069] The feed materials of Example 2 or Comparative example 1 are mixed at room temperature, adding the isocyanate and mixing for 60 s in a speed mixer (FA Hauschild), then pouring the reaction mixture into a 20300.4 cm metal mold or 20300.2 cm, wipe off the excess resin with a squeegee. The reaction mixture is cured at 40 C. for 1 hour. Then test specimens measuring 4 mm80 mm10 mm are punched out for the measurement of the heat resistance. Some of these test specimens are annealed in accordance with the information in Table 2 and then the heat resistance is measured. The results illustrate the course of the reaction. In the presence of a radical inhibitor, the reaction at temperatures below 80 C. was only partial. The reaction product is storable and sticky in this state. Due to higher temperatures >120 C., the heat resistance of the example according to the invention increases significantly by more than 100 C. and only then reaches the final properties.

[0070] The heat resistance of the example according to the invention with complete curing is (160 C.) clearly above the comparison example. 1 with radical starter (120 C.).

Table 3

[0071] <img class=EMIRef id=598068494-imgf000019_0001/>

[0072] Table 3: Example 3 (with catalyst) shows better heat resistance and at the same time significantly better impact resistance than Example 4 (without catalysts).

Table 4

[0073] <img class=EMIRef id=598068494-imgf000020_0001/>

[0074] The Examples in Table 4 show formulations which are particularly suitable for the vacuum infusion process and, because of the lower viscosity of Example 5 according to the invention, allow the component to be filled quickly. A higher heat resistance is found than in the comparative example.

3.

Table 5

[0075] <img class=EMIRef id=598068494-imgf000021_0001/>

Table 5: Preparation of Prepreg

Production of a Laminate (Unidirectional Pre-Impregnated Semi-Finished Textile)

[0076] The starting materials (Table 5) are mixed at room temperature. The reaction mixture is then continuously filled into an open bath at room temperature using a metering system. The pre-treatment is carried out analogously to the wet winding process. A total of 42 rovings (external take-off, use of thread brakes for each roving) Tex 2400 are first fed through a perforated plate and then continuously through the impregnation bath. The excess resin is separated by means of the wipers integrated in the soaking device and can run back into the bathroom so that no resin drips from the impregnated rovings. The impregnated rovings are then passed through a metallic hole measuring 5.50.2 cm, placed between release paper and cured at 80 C. The 5.5 cm wide unidirectional prepreg produced in this way can be wound up on a spool after passing through the heating section.

[0077] The prepreg is a non-sticky, solid mass and can be deformed manually without the use of tools. The prepregs produced in this way are unwound and several 30 cm long pieces are cut off. Two layers of prepreg are placed in the mold, fiber orientation 0, 90. The mold is then closed and first heated to 120 C. for 1 hour and then to 150 C. for 1 hour. A hard, three-dimensional component that can no longer be manually deformed can then be removed. The fiber volume content is 60%.

[0078] Polyol 1: Propoxylated/ethoxylated mixture of sucrose and diethylene glycol, OHZ 400 and a functionality of 4.5, viscosity 3000 mPas [25 C.]

[0079] Polyol 2:: branched fatty acid ester, OHZ 173, viscosity 3400 mPas [25 C.] polyol 3: non-NCO reactive fatty acid ester, viscosity 7 mPas [25 C.]

[0080] Polyol 4:, propoxylated mixture of sucrose and glycerin, OHZ 490 and a functionality of 4.4, viscosity 8450 mPas [25 C.]

[0081] Polyol 5:, propoxylated glycerin OHZ 805, viscosity 1275 mPas [25 C.]

[0082] Polyol 6:, propoxylated glycerin, OHZ 400, viscosity 375 mPas [25 C.] Polyol 7:, propoxylated propylene glycol, OHZ 248, viscosity 75 mPas [25 C.]

[0083] Polyol 8: castor oil, OHZ 160, viscosity 1025 mPas [25 C.]

[0084] Polyol 9: cationically propoxyated glycerol, OHZ 555, viscosity 690 mPas [25 C.]

[0085] TMPTA: trimethylolpropane triacrylate catalyst 1: 40% solution of potassium acetate in DPG radical initiator 1: benzoyl peroxide radical inhibitor 1: phenothianzine defoamer 1: Efka SI 2008, BASF SE defoamer 2: Efka SI 2723, BASF SE

[0086] Isocyanate 1 1:1 mixture of a prepolymer based on 4,4-MDI, dipropylene glycol/polypropylene glycol and carbodiimide-modified 4,4-MDI with an NCO content of 26%.

[0087] Isocyanate 2: 1:1 mixture of polymer MDI and a 1:1 mixture of 2,4-MDi and 4,4-MDI with an NCO content of 32.5%. Tests:

[0088] Viscosity according to DIN 53019-1 to 3

[0089] Shore hardness test D according to DIN ISO 7619-1

[0090] 3-Point bending test according to DIN EN ISO 178

[0091] Tensile strength according to DIN EN ISO 527

[0092] Charpy impact resistance (flatwise) according to DIN En ISO 179-1/1fU

[0093] Heat resistance: HDT-B-f, flat three-point bending at 0.45 MPa edge fiber tension according to DIN EN ISO 75