FOAM MATERIAL PARTICLES BASED ON LONG-CHAIN POLYAMIDES

Abstract

Foam particles that have a bulk density below 300 kg/m.sup.3 and are based on polyamides, including 85% to 100% by weight of at least one copolyamide obtainable by polymerizing the following components: (A) 15% to 84% by weight of at least one lactam, (B) 16% to 85% by weight of a monomer mixture (M) including the following components: (B1) at least one C.sub.32-C.sub.40 dimer acid and (B2) at least one C.sub.4-C.sub.12 diamine, wherein the monomer mixture (M) includes in the range from 45 to 55 mol % of component (B1) and in the range from 45 to 55 mol % of component (B2), based on the total molar amount of the monomer mixture (M), and the sum total of the components of (A) and (B) is 100% by weight, and processes for production thereof.

Claims

1. Foam particles that have a bulk density below 300 kg/m.sup.3 and are based on polyamides, comprising 85% to 100% by weight of at least one copolyamide obtainable by polymerizing the following components: (A) 15% to 84% by weight of at least one lactam, and (B) 16% to 85% by weight of a monomer mixture (M) comprising the following components: (B1) at least one C.sub.32-C.sub.40 dimer acid, and (B2) at least one C.sub.4-C.sub.12 diamine, wherein the monomer mixture (M) comprises in the range from 45 to 55 mol % of component (B1) and in the range from 45 to 55 mol % of component (B2), based on the total molar amount of the monomer mixture (M), and the sum total of the components of (A) and (B) is 100% by weight.

2. Foam particles according to claim 1, which consist of 85% to 100% by weight of the copolyamide and 0% to 15% by weight of additives.

3. Foam particles according to claim 1, which have a bulk density in the range of 30-250 kg/m.sup.3.

4. Foam particles according to claim 1, wherein component (A) is selected from the group consisting of 3-aminopropanolactam, 4-aminobutanolactam, 5-aminopentanolactam, 6-aminohexanolactam, 7-aminoheptanolactam, 8-aminooctanolactam, 9-aminononanolactam, 10-aminodecanolactam, 11-aminoundecanolactam, and 12-aminododecanolactam.

5. Foam particles according to claim 1, wherein component (B2) is selected from the group consisting of tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, decamethylenediamine, and dodecamethylenediamine.

6. Foam particles according to claim 1, wherein the copolyamide has a glass transition temperature (T.sub.g) in the range from 20 to 50° C., determined according to ISO 11357-2:2014.

7. Foam particles according to claim 1, wherein the copolyamide has a melting temperature (T.sub.m) in the range from 150 to 210° C., determined according to ISO 11357-2:2014.

8. A process for producing foam particles according to claim 1, the process comprising the stages of: (a) providing a polymer or polymer mixture comprising 85% to 100% by weight of at least one copolyamide, obtainable by polymerizing the following components: (A) 15% to 84% by weight of at least one lactam, and (B) 16% to 85% by weight of a monomer mixture (M) comprising the following components: (B1) at least one C.sub.32.sup.-C.sub.40 dimer acid, and (B2) at least one C.sub.4-C.sub.12 diamine, wherein the monomer mixture (M) comprises in the range from 45 to 55 mol % of component (B1) and in the range from 45 to 55 mol % of component (B2), based on the total molar amount of the monomer mixture (M), and the sum total of the components of (A) and (B) is 100% by weight; (b) impregnating the polymer or polymer mixture with carbon dioxide, nitrogen or mixtures thereof as blowing agent; and (c) expanding the blowing agent-containing polymer or polymer mixture under foaming to give foam particles.

9. The process according to claim 8, wherein, in stage (b), pellets of the polymer or polymer mixture are impregnated with gaseous carbon dioxide, nitrogen or mixtures thereof in an autoclave at a pressure in the range of 18 to 25 MPa at a temperature in the range from 180 to 250° C. for 1 to 5 hours.

10. The process according to claim 8, wherein, in stage (b), the polymer or polymer mixture is melted and the polymer melt is impregnated with carbon dioxide, nitrogen or mixtures thereof.

11. A process for producing foam particles according to claim 1, the process comprising the steps of: (a) providing a polymer or polymer mixture comprising 85% to 100% by weight of at least one copolyamide, obtainable by polymerizing the following components: (A) 15% to 84% by weight of at least one lactam, and (B) 16% to 85% by weight of a monomer mixture (M) comprising the following components: (B1) at least one C.sub.32.sup.-C.sub.40 dimer acid, and (B2) at least one C.sub.4-C.sub.12 diamine, wherein the monomer mixture (M) comprises in the range from 45 to 55 mol % of component (B1) and in the range from 45 to 55 mol % of component (B2), based on the total molar amount of the monomer mixture (M), and the sum total of the components of (A) and (B) is 100% by weight; (b) melting the polymer or polymer mixture together with 0% to 1% by weight of a nucleating agent and impregnating by addition of 1% to 3.5% by weight of carbon dioxide, nitrogen or mixtures thereof as blowing agent, based in each case on the polymer or polymer mixture; (c) extruding the blowing agent-containing polymer melt through a perforated plate at a temperature between 200° C. and 280° C. into a pelletizing chamber; and (d) discharging the expanded foam particles from the pelletizing chamber, wherein water at a temperature of 5 to 90° C. flows through the pelletizing chamber at a pressure of 0.1 bar to 20 bar above ambient pressure.

12. The process according to claim 8, wherein the copolyamide used has a water content in the range from 0.05% to 1.0% by weight, determined according to DIN EN ISO 15512:2017-03.

13. A method of using of the foam particles according to claim 1, the method comprising using the foam particles for production of foam moldings for the automotive industry, wind power industry, building industry, packaging industry, sports and leisure industry, in transport, and/or in construction.

14. The process according to claim 11, wherein the copolyamide used has a water content in the range from 0.05% to 1.0% by weight, determined according to DIN EN ISO 15512:2017-03.

Description

EXAMPLES

[0106] Raw Materials Used: [0107] PA6.6/36 Ultramid RX2240, high-viscosity copolyamide from BASF SE, melting point 199° C. to ISO 3146, density to ISO 1183 of 1.1 g/cm.sup.3 [0108] PA6 Ultramid® B27, nylon-6 from BASF SE [0109] Talc IT Extra microscale talc, Mondo Minerals

[0110] Test Methods:

[0111] Bulk density was determined in accordance with DIN ISO 697:1984-01 by filling a 500 ml vessel with the expanded particles and determining the weight by means of a balance.

[0112] The water content of the polyamide used was determined to DIN EN ISO 15512:2017-03.

Example 1: Melt Extrusion

[0113] 99.5 parts by weight of PA6.6/36 polyamide having a water content of 0.134% by weight was melted in a twin-screw extruder (screw diameter 18 mm, length/diameter (L/D) ratio=40) at 250° C. and mixed with 0.5 part by weight of talc. Subsequently, CO.sub.2 or a mixture of CO.sub.2/N.sub.2 as blowing agent was metered into the melt, mixed homogeneously and extruded through a perforated plate (hole diameter 1 mm). The perforated plate was electrically heated by means of heating cartridges and kept at a temperature of 280° C. or 240° C. The extruded strand was pelletized by underwater pelletization (UWP) at a pressure of 1 MPa to give foam particles having an average diameter of 2 mm and an average weight of 2 mg by means of 10 blades secured to a rotating blade ring.

[0114] The amounts of the blowing agent added to the polymer melt (based on 100 parts polyamide/talc melt), the temperature of the blowing agent-laden melt and of the perforated plate, and the bulk density of the resulting foam particles are collated in table 1.

TABLE-US-00001 TABLE 1 Temperature Temperature CO.sub.2 N.sub.2 [C.] of the [C.] of the Bulk [% by [% by melt before the perforated density Example wt.] wt.] perforated plate plate [kg/m.sup.3] 1.1 1.96 — 251 280 348 1.2 1.96 0.29 251 280 170 1.3 1.96 0.29 222 240 170 1.4 2.90 0.29 223 240 124

Example 2 and Comparative Experiments: Autoclave Method

[0115] 20 PA6.6/36 pellets were introduced into a conventional stainless steel tea strainer and placed in a high-pressure autoclave. The autoclave was closed, CO.sub.2 or N.sub.2 was injected at a pressure 20 MPa, and impregnation was effected at a temperature in the range from 180 to 235° C. for 3 hours. Subsequently, the autoclave was decompressed abruptly by opening a ball valve. After the autoclave had been cooled to room temperature, the foamed polyamide particles were removed.

[0116] The impregnation conditions and foaming characteristics are collated in table 2.

TABLE-US-00002 TABLE 2 Impreg- Impreg- nation Foaming Bulk Poly- nation temperature charac- density Example amide medium [C.] teristics [kg/m.sup.3] 2.1 PA6/6.36 CO.sub.2 180 Not foamed 1100 2.2 PA6/6.36 CO.sub.2 205 Well foamed  200 2.3 PA6/6.36 CO.sub.2 210 Overfoamed, — many cavities V1 PA6 N.sub.2 180 Not foamed 1140 V2 PA6 N.sub.2 205 Very lightly  700 foamed, opaque V3 PA6 N.sub.2 210 Overfoamed, — hollow structure no particle retention

[0117] In the temperature range of 210-250° C., in which the PA 6/6.36 is processed in the extruder, viscosity is virtually constant. This leads to a more stable particle foam. In the case of PA 6, by contrast, viscosity falls significantly within the temperature range mentioned.