POLYAMIDE COMPOSITIONS COMPRISING REINFORCING FIBERS AND HAVING HIGH MODULUS STABILITY, AND USES THEREOF

Abstract

The present invention relates to the use of a mixture of at least one semi-crystalline aliphatic polyamide and at least one amorphous polyamide, wherein the at least one semi-crystalline aliphatic polyamide is obtained by polycondensation: of at least one C.sub.6 to C.sub.18, preferentially C.sub.10 to C.sub.18, more preferentially C.sub.10 to C.sub.12 amino acid, or at least one C.sub.6 to C.sub.18, preferentially C.sub.10 to C.sub.18, more preferentially C.sub.10 to C.sub.12 lactam, or at least one C.sub.4-C.sub.36, preferentially C.sub.5-C.sub.18, preferentially C.sub.5-C.sub.12, more preferentially C.sub.10-C.sub.12 diamine Ca, with at least one C.sub.4-C.sub.36, preferentially C.sub.6-C.sub.18, preferentially C.sub.6-C.sub.12, more preferentially C.sub.10-C.sub.12 dicarboxylic acid Cb; in order to prepare a semi-crystalline composition, the modulus of which does not vary by more than 25% within the temperature range from 10° C. to 40° C.

Claims

1. A use of a mixture of at least one semi-crystalline aliphatic polyamide and at least one amorphous polyamide wherein said at least one semi-crystalline aliphatic polyamide is obtained by polycondensation: of at least one C.sub.6 to C.sub.18, or of at least one C.sub.6 to C.sub.18, or of at least one C.sub.4-C.sub.36 aliphatic diamine Ca with at least one C.sub.4-C.sub.36 aliphatic dicarboxylic acid Cb; for preparing a semi-crystalline composition whose tensile or flexural modulus does not vary by more than 25% in the temperature range from 10° C. to 40° C.

2. The use according to claim 1, wherein the modulus does not vary by more than 35% in the temperature range of −10° C. to 50° C.

3. The use according to claim 1, wherein the Tg of said semi-crystalline composition, determined by DMA according to ISO 6721-11:2019, shows an increase greater than or equal to 5° C. with respect to the initial Tg of said semi-crystalline polyamide before mixing.

4. The use according to claim 1, wherein said at least one amorphous polyamide is a homopolyamide of formula XY or a copolyamide of formula A/XY, XY being a repeating unit obtained by polycondensation of at least one cycloaliphatic diamine (X) and at least one C.sub.4-C.sub.36 aliphatic dicarboxylic acid (Y) or of at least one aromatic dicarboxylic acid (Y) and A is a repeating unit obtained by polycondensation of at least one C.sub.6 to C.sub.18 amino acid, or of at least one C.sub.6 to C.sub.18 lactam, or of at least one C.sub.4-C.sub.36 Ca diamine with at least one C.sub.4-C.sub.36 dicarboxylic acid Cb.

5. The use according to claim 4, wherein said at least one amorphous polyamide is a copolyamide of formula A/XY, A being obtained by polycondensation of at least one amino acid or obtained by polycondensation of at least one lactam, X being selected from bis-(3-methyl-4-aminocyclohexyl)-methane (B) or bis(p-aminocyclohexyl)-methane (P) or bis(aminomethyl)cyclohexane (BAC) and Y being terepthalic and/or isophthalic acid.

6. The use according to claim 4, wherein A/XY is selected from the units 11/BI/BT, 12/BI/BT, 11/BACI/BACT, 12/BACI/BACT, 11/BACI, 12/BACI, 11/PI/PT, 12/PI/PT and a mixture thereof.

7. The use according to claim 4, wherein said at least one amorphous polyamide is a copolyamide of formula A/XY, A being obtained by polycondensation of at least one amino acid or obtained by polycondensation of at least one lactam, X being selected from bis-(3-methyl-4-aminocyclohexyl)-methane (B) or bis(p-aminocyclohexyl)-methane (P) and Y being sebacic acid or dodecanedioic acid.

8. The use according to claim 4, wherein A/XY is selected from 11/B10, 11/B12, 11/P10, 11/P12, 12/B10, 12/B12, 12/P10, 12/P12, and a mixture thereof.

9. The use according to claim 4, wherein said at least one amorphous polyamide is a copolyamide of formula A/XY, A being obtained by polycondensation of at least one diamine Ca with at least one dicarboxylic acid Cb, X being selected from bis-(3-methyl-4-aminocyclohexyl)-methane (B) or bis(p-aminocyclohexyl)-methane (P) and Y being sebacic acid or dodecanedioic acid.

10. The use according to claim 4, wherein A/XY is selected from 1010/B10, 1010/B12, 1010/P10, 1010/P12, 1012/B10, 1012/B12, 1012/P10, 1012/P12, 1210/B10, 1210/B12, 1210/P10, 1210/P12, 1212/B10, 1212/B12, 1212/P10, 1212/P12, and a mixture thereof.

11. The use according to claim 4, wherein said at least one amorphous polyamide is a homopolyamide of formula XY, X being selected from bis-(3-methyl-4-aminocyclohexyl)-methane (B) or bis(p-aminocyclohexyl)-methane (P) and Y being sebacic acid or dodecanedioic acid.

12. The use according to claim 4, wherein XY is selected from units B10, B12, P10, P12, and a mixture thereof.

13. The use according to claim 1, wherein said semi-crystalline copolyamide, has an enthalpy of crystallization greater than 30 J/g.

14. The use according to claim 1, wherein the proportion by weight of said amorphous polyamide is from 10 to 45% by weight with respect to the sum by weight of said at least one semi-crystalline polyamide and of said at least one amorphous polyamide.

15. The use according to claim 1, wherein the composition comprises 35 to 75% by weight of reinforcing fibers.

16. The use according to claim 15, wherein the reinforcing fibers are selected from glass fibers and carbon fibers, or a mixture thereof.

17. The use according to claim 16, wherein the glass fibers are selected from glass fibers with a non-circular cross-section and glass fibers with a circular cross-section, carbon fibers, and a mixture thereof.

18. A composition, particularly useful for injection molding, comprising: from 25 to 65% by weight of a mixture of at least one semi-crystalline aliphatic polyamide and of at least one amorphous polyamide according to claim 1, from 35 to 75% by weight of reinforcing fibers; from 0 to 10% by weight of at least one impact modifier; from 0 to 30% by weight of at least one filler; and from 0 to 10% by weight of at least one fluidifying agent; and from 0 to less than 2% by weight of additives; the sum of the proportions of each constituent of said composition being equal to 100%.

19. A method of manufacturing the composition as defined in claim 18, wherein the constituents of the said composition are mixed by compounding a co-mixer or an internal mixer.

20. A molded article obtainable from the composition according to claim 18, by injection molding.

21. The molded article according to claim 20 for electrical applications and electronics selected from the group consisting of televisions, digital cameras, digital games, telephone parts, digital tablets, drones, printers or computer parts.

22. The molded article according to claim 20, for sport applications, a ski boot or a ski boot part or a rigid shoe with cleats, or a running shoe, a golf ball or a part of a golf ball, or a lacrosse stick or also a hockey article.

Description

EXAMPLES

[0278] The invention will be explained in more detail in the following examples.

Example 1: Synthesis of the (Co)Polyamides of the Invention

[0279] The various polyamides and copolyamides of the invention were prepared according to the usual techniques for polyamide and copolyamide synthesis.

[0280] Synthesis of PA B10, representative of the various homopolyamides:

the monomers bis-(3-methyl-4-aminocyclohexyl)-methane (B) and sebacic acid are loaded together into the reactor. The medium is first inerted to remove the oxygen that can generate yellowing or secondary reactions. Water can also be loaded to improve heat exchange and encourage the monomers to melt. Two temperature rise and pressure plateaus are conducted. The temperature (T°) and pressure conditions are chosen to allow the medium to melt. After having reached the maintenance conditions, degassing takes place to allow the polycondensation reaction. The medium becomes viscous little by little and the reaction water formed is caused the nitrogen purge or applying a vacuum. When the stoppage conditions are reached, related to the desired viscosity, stirring is stopped and the extrusion and granulation can start. The granules obtained will then be compounded with the glass fibers.

[0281] Synthesis of PA 11/B10, representative of the various copolyamides:

the monomers aminoundecanoic acid, bis-(3-methyl-4-aminocyclohexyl)-methane (B) and sebacic acid are loaded together into the reactor according in the desired mass ratio. The medium is first inerted to remove the oxygen that can generate yellowing or secondary reactions. Water can also be loaded to improve heat exchange and encourage the monomers to melt. Two temperature rise and pressure plateaus are conducted. The temperature (T°) and pressure conditions are chosen to allow the medium to melt. After having reached the maintenance conditions, degassing takes place to allow the polycondensation reaction. The medium becomes viscous little by little and the reaction water formed is caused the nitrogen purge or applying a vacuum. When the stoppage conditions are reached, related to the desired viscosity, stirring is stopped and the extrusion and granulation can start. The granules obtained will then be compounded with the glass fibers.

Compounding

[0282] The compositions were prepared by mixing the polymer granules with the short fibers when melted. This mixing was carried out by compounding on a co-rotating twin-screw extruder with a screw diameter of 26 mm with a flat temperature profile (T°) at 290° C. for compositions CE1 to CE3 and I1 to I8 and at 230° C. for compositions I9 and I10 and CE4. The screw speed is 250 rpm and the flow rate is 20 kg/h.

[0283] The introduction of the glass fibers is achieved by side feeding.

[0284] The (co)polyamides, fibers, additives and possibly fillers are added during the compounding process in the main hopper for compositions CE1 to CE3 and I1 to I8.

[0285] For the compositions I8 and I9 and CE4, the resins and additives are introduced in the main hopper and the addition of the fillers is done by a first lateral gutter and the glass fibers in a second lateral gutter.

[0286] The following compositions were prepared (E=Example of the invention CE=Comparative example, the values correspond to percentages by weight):

TABLE-US-00001 TABLE 1 Composition CE1 CE2 CE3 I1 I2 I3 I4 I5 I6 I7 I8 B10 7.89 7.89 PA1010 39.46 31.57 11/B10 7.90 9.90 11.80 9.90 9.90 12/B10 9.90 PA11 39.46 31.56 29.56 27.66 29.56 24.56 31.57 PA12 39.46 29.56 PA11 5.00 prepolymer monoNH2 Antioxidant 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.24 0.24 Calcium 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 stearate Glass fibers 60.00 60.00 60.00 60.00 60.00 60.00 60.00 60.00 60.00 60.00 60.00 CSX3J- 451

TABLE-US-00002 TABLE 2 Composition I9 I10 CE4 11/B10 9.00 7.40 PA11 35.40 29.50 47.46 Flame retardant 15 22.5 20 PA11 prepolymer monoNH2 Antioxidant 0.30 0.30 0.24 Calcium stearate 0.30 0.30 0.30 Glass fibers CSX3J- 451 40.00 40.00 30.00 MB BMNO Bk TL (Black 2.00 masterbatch based on PA11) The values are percentages by weight.

[0287] BMNO: Rilsan® BMNO marketed by Arkema

[0288] Flame retardant: OP1312 (Clariant)

[0289] CSX3J-451 circular cross-section fibers marketed by Nittobo

[0290] Injection

[0291] 100*100*1 mm.sup.3 plates were prepared by injecting the different compositions: [0292] Injection temperature: 260° C. [0293] Mold temperature: 80° C.

[0294] The cycle time is adjusted according to the compositions to allow injection of the compositions and is less than 50 seconds.

[0295] Compositions I1 to I10 all have a Tg relative to the comparative compositions CE1 to CE3 greater than 5° C.

[0296] The polyamide blends of compositions I1-I8 in Table 1 and I9-I10 in Table 2 all have crystallization enthalpies greater than 30 J/g.

Example 2: Change in Flexural Modulus with Temperature and Humidity

[0297] In order to evaluate the impact of humidity and temperature on the flexural modulus, the flexural modulus of specimens of the compositions obtained was measured on an Instron 5966 machine manufactured by the Instron company. The compositions are dried compositions and compositions saturated in water at 65° C. beforehand.

[0298] The tests were carried out at different temperatures, from −10° C. to 60° C.

[0299] In the injection-molded plates, specimens with dimensions according to ISO 178 but with a thickness of 1 mm were cut out in the direction of injection.

[0300] The results are shown in Tables 3 to 4 below:

TABLE-US-00003 TABLE 3 modulus loss in saturated state (%) (M-10 − MT/M-10) × 100 CE1 CE2 CE3 CE4 I1 I2 I3 I4 I5 I6 I7 I8 I9 I10 −10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 3 3 5 1 1 1 1 1 1 2 3 3 6 10 11 9 10 12 3 3 3 3 3 3 5 6 6 9 20 22 20 21 22 6 5 4 5 5 4 9 10 9 12 30 32 31 33 32 10 8 8 9 8 8 15 17 15 17 40 40 39 39 39 17 13 11 14 14 12 24 25 21 23 50 45 43 45 43 23 20 17 21 21 18 30 31 28 30 60 47 45 48 45 30 28 24 28 28 24 37 38 34 35

TABLE-US-00004 TABLE 4 Change in modulus between dry and saturated state (%) CE1 CE2 CE3 CE4 I1 I2 I3 I4 I5 I6 I7 I8 I9 I10 20° C. 33 30 34 24 4 −2 −9 7 3 −1 15 15 15 12

[0301] Table 4 shows that the compositions of the invention have a higher flexural modulus stability than the comparison compositions CE1 and CE4.

Example 3: Change in Tensile Modulus with Temperature and Humidity

[0302] In order to evaluate the impact of humidity and temperature on the tensile modulus, the tensile modulus of specimens of the compositions obtained was measured on an Instron 5966 machine manufactured by the Instron company. The compositions are dried compositions and compositions saturated in water at 65° C. beforehand.

[0303] The tests were carried out at different temperatures, from −10° C. to 60° C.

[0304] In the injection-molded plates, specimens with dimensions according to ISO 527 but with a thickness of 1 mm were cut out in the direction of injection.

[0305] The same trends as those observed for flexural modulus are found for tensile modulus.