Polyamide composition

Abstract

A polyamide composition comprising, based on the total weight of the composition: A) from 30 to 94.87 wt.% of one or more polyamide materials, B) from 5 to 20 wt.% of one or more inorganic white pigment materials, C) from 0.03 to 1.5 wt.% of one or more carbon nanotube materials, and D) from 0.1 to 2.0 wt.% of one or more a metal-free organic dyes.

Description

POLYAMIDE COMPOSITIONFIELD OF THE INVENTION

[0001] The present disclosure relates to a polyamide composition comprising carbon nanotubes and non-metallic dye and showing excellent antistatic properties.BACKGROUND OF THE INVENTION

[0002] A build-up of static electricity may occur when there is a sliding, rubbing or separating of material. In a material having low electric conductivity, such as plastic, the charge may remain within a localized area and may be discharged via an arc or spark when the material comes into contact with a body having a sufficiently different electrical potential, such as a person or microcircuit.

[0003] Known as electrostatic discharge, this sudden flow of electricity between two differently electrically charged objects can have catastrophic effects. If electrostatic discharge occurs to a person, they may experience anything from a mild to a painful shock, or, in extreme cases, loss of life. An electrical spark is especially dangerous in environments that contain flammable liquids, solids or gasses, such as a hospital operating room. But the most common casualties of electrostatic discharge are sensitive electronic components. Some micro-electronic parts can be destroyed or damaged by electrostatic discharge as low as 20 V. The consequences of electrostatic discharge damage to an electrical component may range from faulty readings to permanent damage, all of which result in equipment downtime and costly repairs. Antistatic and static dissipative plastics are used to minimize the risk of electrostatic discharge and reduce breakdowns.

[0004] Problems with static electricity in the plastics processing industries are also numerous. Processes where static charge can be an issue include injection molding, blow molding, thermoforming, rotational molding, parts conveying and collection and assembly processes. The primary problems resulting from high levels of static charge are dust attraction and contamination, process control and quality problems, and operator shocks.1FR7744-WO-01

[0005] Plastics, by nature, are normally insulators. Parts made from non-conductive plastics tend to accumulate and retain a static charge very easily. In contrast, parts made from conductive plastics maintain a zero potential and do not accumulate static charges. This property is valuable for reducing the risk of an unwanted electrostatic discharge. Consequently, conductive plastic parts are the right choice for applications where the presence of static electricity may increase the risk of a fire, explosion, or malfunction of other electrical components and devices.

[0006] Conductive plastic parts offer a number of advantages over parts made from metals or other materials coated or painted with surfactants. Finished conductive plastic parts are lighter in weight, easier to handle and generally less costly to transport and ship than their metal counterparts.

[0007] Conductive plastics can also be used to produce parts which shield and protect electronic components from the effects of electromagnetic interference (EMI). These parts form a conductive path for electromagnetic waves, diverting them away from sensitive electronic components which could be easily damaged.

[0008] There are various ways to produce plastics that have the desired conductive properties. The basic approach is to combine conductive polymers, particles or fibers with a base polymer, to form a conductive plastic. This can then be compounded and used to produce plastic materials from which parts can be either machined or molded.

[0009] It is known in the art that carbonaceous additives, especially carbon black, may improve the conductivity of plastics, such as polyamide, and provide antistatic properties.

[0010] WO2018 / 138256A1 teaches a black-colored polyamide composition which comprises a chromium-containing azo dye in the form of a chromium complex and carbon black and glass fibers, and the use of the composition for producing polyamide molded bodies which are laser-writable and dyed in black. Because these compositions and injection molded items made thereof are black, their final application is limited.

[0011] EP 3 312 224 A1 discloses a polyamide molding composition having excellent adhesion to metal surfaces and structural parts with a metal component directly bonded to a thermoplastic component. These compositions and products made thereof are likewise limited to being black.2FR7744-WO-01

[0012] Conductive or anti-static items made from plastics, such as polyamide, are generally too dark to be made distinguishable using different colors. It was therefore an object of the disclosure to provide a conductive polyamide composition that is colored differently from black.SUMMARY OF THE INVENTION

[0013] In a first aspect the present disclosure concerns a polyamide composition that comprises, based on the total weight of the composition,A) from 30 to 94.87 wt.% of one or more polyamide materials, B) from 5 to 20 wt.% of one or more inorganic white pigment materials, C) from 0.03 to 1.5 wt.% of one or more carbon nanotube materials, and D) from 0.1 to 2.0 wt.% of one or more metal-free organic dyes.

[0014] In a second aspect, the present disclosure concerns a process for preparing a polyamide composition comprising a step a) of simultaneously or sequentially adding to a polyamide material A):B) from 5 to 20 wt.% of one or more inorganic white pigment materials, C) from 0.03 to 1.5 wt.% of one or more carbon nanotube materials, and D) from 0.1 to 2.0 wt.% of one or more metal-free organic dyes,

[0015] wherein the amounts of components B), C) and D) are based on the total weight of the composition.

[0016] In a third aspect the present disclosure concerns polyamide products comprising the polyamide composition.

[0017] It has been found that the polyamide composition of the present disclosure is static dissipative, but is not black, despite the content in carbon nanotube material. Instead, the claimed composition is colored and allow the production of articles for a diverse range of uses, such as in housing, shielding, packaging films, fabric and sensors.

[0018] Advantageously, carbon nanotube (CNT) material C) forms a conductive network in the polyamide composition. This provides permanent antistatic, static dissipative or conductive properties to the polyamide composition, with low required amounts of the CNT material. Furthermore, the combination with metal-free dye and white pigment allows to obtain polyamide compositions and products that are3FR7744-WO-01permanently colored, without any loss or lowering of the electrical conductive properties.

[0019] While multiple embodiments are disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description. As will be apparent, certain embodiments, as disclosed herein, are capable of modifications in various obvious aspects, all without departing from the spirit and scope of the claims as presented herein. Accordingly, the following detailed description is to be regarded as illustrative in nature and not restrictive.DETAILED DESCRIPTION OF THE INVENTION

[0020] In the context of the present disclosure:

[0021] - the percentages are expressed by weight, unless otherwise specified;

[0022] - the total weight of a composition sums up to 100% by weight, unless otherwise specified;

[0023] - the term “insulating" refers to materials with a surface resistivity of more than 1012Ohm / sq;

[0024] - the terminology “static dissipative” refers to materials with a surface resistivity of 105to 1012Ohm / sq;

[0025] - the term “antistatic" refers to materials with a surface resistivity of 109to 1012Ohm / sq;

[0026] - the term “conductive" refers to materials with a surface resistivity of less than 105Ohm / sq;

[0027] - the terminology “non-permanent antistatic” refers to polymer material with externally applied antistatic agents or migrating types of bulk additives;

[0028] - the term “permanent antistatic” refers to polymer material with nonmigrating bulk additives;

[0029] - the terminology “metal-free” as used in the context of organic dye refers to dyes that do not comprise metal atoms; and

[0030] - the terminology “metal-comprising” refers to dyes with a metal-containing chromophore. Dyes that merely comprise metal impurities, e.g. from the synthesis of the dye molecule, should not be understood as “metal-comprising”.

[0031] According to the present disclosure, the polyamide composition comprises, based on the total weight of the composition:4FR7744-WO-01A) from 30 to 94.87 wt.% of one or more polyamide materials,B) from 5 to 20 wt.% of one or more inorganic white pigment materials, C) from 0.03 to 1.5 wt.% of one or more carbon nanotube materials, and D) from 0.1 to 2.0 wt.% of one or more a metal-free organic dyes.

[0032] Preferably, the polyamide composition has(i) a lightness L* of 30 or more in the CIE L*a*b* system, determined according to the method described in the experimental section.

[0033] More preferably, the polyamide composition has a lightness L* in a range of from 35 to 60 in the CIE L*a*b system, determined according to the method described in the experimental section. With Lightness L* in this range, differently colored polyamide compositions may be easily distinguishable.

[0034] Preferably, the polyamide composition has(ii) a surface resistivity of 1.0x1012Ohm / sq or less, determined according to IEC 62631-3-2.

[0035] With this surface resistivity polyamide compositions are not insulating but have satisfactory antistatic behavior and will show a charge decay over time, e.g. within less than one minute.

[0036] More preferably, the polyamide composition has(ii) a surface resistivity of 1.0x101° Ohm / sq or less, determined according to IEC 62631-3-2.

[0037] With this surface resistivity polyamide compositions have very good antistatic behavior show a charge decay over time within a few seconds.

[0038] In some embodiments, the polyamide composition has

[0039] (ii) a surface resistivity of 1.0x105Ohm / sq or more, determined according to IEC 62631-3-2.

[0040] At a low surface resistivity, polyamide compositions become conductive and unsuitable for some applications.

[0041] Preferably, the polyamide composition comprises, based on the total weight of the composition, A) from 40 to 87.55 wt.% of one or more polyamide materials.

[0042] Preferably, component A) comprises a polyamide selected from Polyamide 6 (PA6), Polyamide 66 (PA66), Polyamide 12 (PA12) and combinations thereof.5FR7744-WO-01

[0043] Preferably, the polyamide composition comprises, based on the total weight of the composition, B) from 7 to 15 wt.% of one or more inorganic white pigment materials.

[0044] Inorganic white pigments are preferably selected from oxides, carbonates, sulfates, sulfides, and silicates (as anions) of Zinc, Titanium, Aluminum, Calcium, Antimony, Lead and Barium (as cations), and combinations thereof. More preferably the white pigments are selected from zinc oxide, zinc sulfide, titanium dioxide and combinations thereof.

[0045] Preferably, zinc sulfide constitutes at least 20 wt.% of component B), based on the total weight of component B). More preferably, zinc sulfide constitutes at least 50 wt.% of component B), based on the total weight of component B), most preferably zinc sulfide constitutes at least 80 wt.% of component B), based on the total weight of component B). In a particularly preferred embodiment, component B) consists of zinc sulfide.

[0046] Preferably, the polyamide composition comprises, based on the total weight of the composition, C)from 0.05 to 1.0wt.% of one or more carbon nanotube materials.

[0047] Preferably, the polyamide composition comprises, based on the total weight of the composition, D) from 0.3 to 1.5 wt.% of one or more a metal-free organic dyes.

[0048] Preferably, the polyamide composition comprises, based on the total weight of the composition, E) from 0.1 to 5.0 wt.%, more preferably from 0.3 to 3 wt.%, of one or more additives selected from lubricants, antioxidants, UV- and light-stabilizers, heat stabilizers, IR absorbers, antiblocking agents, crystal-growth inhibitors, nucleating agents, chain extenders, defoamers, mold-release agents, separating agents, anti-dripping-agents.

[0049] Preferably, the polyamide composition comprises, based on the total weight of the composition, F) from 5 to 50 wt.%, more preferably from 15 to 35 wt.%, of one or more filler materials, preferably fibers.

[0050] Filler material, particularly fibers, is beneficial to reinforce the polyamide material compositions.

[0051] More preferably, component F) comprises glass fiber material. Still more preferably the component F) consists of glass fiber material.6FR7744-WO-01

[0052] Optionally, the polyamide composition comprises, based on the total weight of the composition, G) from 2 to 40 wt.%, preferably from 5 to 30 wt.%, of one or more impact modifiers and / or flame retardant materials.

[0053] Preferably, component C) comprises or consists of single-walled carbon nanotubes.

[0054] In a preferred embodiment the polyamide composition comprises, based on the total weight of the composition,A) from 40 to 87.55 wt.% of one or more polyamide materials, B) from 7 to 15 wt.% of one or more inorganic white pigment materials, C) from 0.05 to 1.0 wt.% of one or more carbon nanotube materials, D) from 0.3 to 1.5 wt.% of one or more a metal-free organic dyes, E) from 0.1 to 5 wt.% of one or more additives selected from lubricants, antioxidants, UV- and light-stabilizers, heat stabilizers, IR absorbers, antiblocking agents, crystal-growth inhibitors, nucleating agents, chain extenders, defoamers, mold-release agents, separating agents, anti- dripping-agents, andF) from 5 to 50 wt.% of one or more fiber filler materials.

[0055] In a more preferred embodiment the polyamide composition comprises, based on the total weight of the composition,A) from 45 to 76.35 wt.% of one or more polyamide materials, B) from 8 to 12 wt.% of one or more inorganic white pigment materials, C) from 0.05 to 1.0 wt.% of one or more carbon nanotube materials, D) from 0.5 to 1.0 wt.% of one or more a metal-free organic dyes, E) from 0.1 to 3 wt.% of one or more additives selected from lubricants, antioxidants, UV- and light-stabilizers, heat stabilizers, IR absorbers, antiblocking agents, crystal-growth inhibitors, nucleating agents, chain extenders, defoamers, mold-release agents, separating agents, anti- dripping-agents, andF) from 15 to 35 wt.% of one or more fiber filler materials.

[0056] Preferably, the polyamide composition has

[0057] - a Tensile Modulus in a range of from 6000 to 12000 MPa, preferably from 10000 to 11000 MPa (ISO 527-1 ,-2); and / or7FR7744-WO-01

[0058] - a Tensile Stress at Break in a range of from 150 to MPa 200 MPa, preferably from 160 to 180 MPa (ISO 527-1,-2); and / or

[0059] - a Tensile Strain at Break in a range of from 2.6 to 3.2 (ISO 527-1 ,-2); and / or

[0060] - a Charpy notched impact (23°C) in a range of from 5 to 15 kJ / m2, preferably 9 to 11 kJ / m2(ISO 179 / 1eA).

[0061] Table A. Compositions according to the disclosure and preferred embodiments

[0062] In a further aspect, the present disclosure refers to a process for preparing the polyamide composition described above comprising a step a) of adding to a polyamide material A)B) from 5 to 20 wt.% of one or more inorganic white pigment materials, C) from 0.03 to 1.5 wt.% of one or more carbon nanotube materials, and D) from 0.1 to 2.0 wt.% of one or more metal-free organic dyes,

[0063] wherein the amounts of components A), B), C) and D) are based on the total weight of the composition.

[0064] Also from 0.1 to 5 wt.% of component E) and / or from 5 to 50 wt.% of component F) and / or from 2 to 40 wt.% of component G) is optionally added to the polyamide A) in step a).

[0065] Step a) is preferably carried out according to methods known in the art, like by compounding the components in an extruder.8FR7744-WO-01

[0066] In one embodiment, components B), C) and D) are simultaneously added to the polyamide A). In this embodiment, the process preferably comprises:

[0067] aO) providing a masterbatch comprising components B), C) and D) and a polymeric carrier resin;

[0068] a1) adding the masterbatch composition to the polyamide A) in an amount to obtain a concentration, based on the total weight of the composition, of from 5 to 20 wt.% of component B), from 0.03 to 1.5 wt.% of component C) and from 0.1 to 2.0 wt.% of component D) in the polyamide composition.

[0069] The polymeric carrier resin comprised in the masterbatch is preferably a polyamide, more preferably selected from Polyamide 6 (PA6), Polyamide 66 (PA66), Polyamide 12 (PA12) and combinations thereof.

[0070] Alternatively, in step a) of the process the components B), C) and D), and optionally component E) and / or component F) and / or component G), are sequentially added to the polyamide A) by feeding the components in different zones of an extruder.

[0071] In one embodiment, the process for preparing the polyamide composition comprises the steps of:

[0072] aO) providing an intermediate colorable polyamide composition comprising:

[0073] A) from 30 to 94.97 wt.% of one or more polyamide materials;

[0074] B) from 5 to 20 wt.% of one or more inorganic white pigment materials,

[0075] C) from 0.03 to 1.5 wt.% of one or more carbon nanotube materials, and

[0076] a1) adding from 0.1 to 2.0 wt.% of one or more metal-free organic dyes D) to the colorable polyamide composition, thereby obtaining the polyamide composition.

[0077] Optionally, the colorable polyamide composition further comprises E) from 0.1 to 5 wt.% of one or more additives and / or F) from 5 to 50 wt.% of one or more filler materials and / or from 2 to 40 wt.% of one or more impact modifier and / or flame retardants.

[0078] Components from A) to G) are as described in the foregoing.

[0079] The polyamide composition according to the present disclosure is particularly useful in producing molded and / or extruded articles, by employing of conventional injection molding, blow molding and / or extrusion techniques. Preferably, these articles are selected from tubing, housing products, shielding products, packaging, films, fabric and sensors. The application of injection molded, blow molded or extruded articles includes the following:9FR7744-WO-01

[0080] - Electrical equipment and devices,

[0081] - Electronic devices and components,

[0082] - Industrial machinery and equipment,

[0083] - Medical devices,

[0084] - Applications governed by ATEX directives requiring the use of plastic materials in hazardous areas (ATEX zones) and the equipment used in those areas,

[0085] - Antistatic environment like clothing, tools, furniture, climate control units, electric boxes,

[0086] - paint system parts,

[0087] - EMI shielding and signal management,

[0088] - Fuel cell components.

[0089] The following examples are given for illustrative purposes and do not intend to limit the scope of the disclosure. All the above preferred embodiments and features are disclosed alone or in any combination with just some or all of the afore and below mentioned embodiments.EXPERIMENTAL PART

[0090] Density was determined according to ISO 1183-1 / A:2019 at 23°C.

[0091] Tensile properties were determined according to ISO 527-1,-2 on 1 A tensile bar test specimens injection molded according to DIN ISO 294-1.

[0092] The Charpy impact test at 23°C was conducted according to ISO 179-1 / 1 ell and ISO 179-1 / 1eA on test specimens injection molded according to DIN ISO 294-1.

[0093] L*a*b* values were measured in the CIELAB color space according to ASTM E308 with a d / 8° geometry sphere spectrophotometer Datacolor 850; illuminating source: pulsed xenon, filtered to approximate D65.

[0094] Surface resistivity was determined according to IEC 62631 -3-2.

[0095] Volume resistivity was determined according to IEC 62631-3-1.RAW MATERIALS

[0096] Component A / Polyamide 6 (PA6): Alphalon 27, a polyamide 6 of medium viscosity (relative viscosity 2.7), a melting point of 220 °C and density of 1.13 g / cm3.

[0097] Component B / White pigment material: Sachtolith HD-S, marketed by Huntsman, a synthetic zinc sulfide with a crystal size of about 0.3 pm, a 45 pm residue of <0.004 % and a brightness L* of about 97.10FR7744-WO-01

[0098] Component C / carbon nanotube material (CNT): Tuball Matrix 822, marketed by OCSiAl, a pelletized concentrate of single wall carbon nanotubes in a carrier of fatty acid ester of polyol with a mass concentration of metal particles of no more than 0.04 %.

[0099] Component D / metal-free organic dye (Dye 1): Solvaperm Green GSB, marketed by Clariant, an anthraquinone dyestuff powder with Color Index Solvent Green 7.

[0100] Component D / metal-free organic dye (Dye 2): Macrolex Red EG Gran, marketed by Lanxess, a perinone dyestuff microgranulate with Color Index Solvent Red 135.

[0101] Component D / metal-free organic dye (Dye 3): Macrolex Blue RR Gran, marketed by Lanxess, an anthraquinone dyestuff microgranulate with Color Index Solvent Blue 97.

[0102] Metal-based dye (not according to the disclosure): Heliogen Green K 8730, marketed by SunChemical, a chlorinated Cu phtalocyanine powder with Color Index Pigment Green.

[0103] Component E1 / Additive 1: Ligastar Zn 101 / 6, marketed by Peter Greven, a zinc stearate powder with a sieve residue >45 pm of no more than 2 %, a melting point of about 120 °C and a metal content of 10.5-11.3 % acting as a lubricant.

[0104] Component E2 / Additive 2: saturated polyol ester acting as lubricant and release agent.

[0105] Component E3 / Additive 3: Irganox 1098 ED, a sterically hindered phenolic antioxidant marketed by BASF.

[0106] Component F / fiber filler materials: ECS 03 T-249H, marketed by Nippon Electric Glass, chopped strands of E-Glass with nominal fiber diameter of 10.5 pm and chop length of 3.0 mm.

[0107] Examples Ex. 1-3 and comparative examples CE 1- 4

[0108] The polymer compositions were prepared by compounding the components shown in table 1 on a continuous twin screw extruder ZSK 26 from Coperion at a melt temperature of 260°C, a throughput of 45 kg / h, and a speed of 400 rpm, and strand pelletized. Glass fibers were dosed via side feeder.11FR7744-WO-01Table 1. Compositions of the examplesTable 2. Properties of the examples12FR7744-WO-01

[0109] As shown in Table 2, the compositions of the disclosure, Examples E1-E3, are in particular characterized by advantageous surface resistivity and volume resistivity, together with high values of lightness L*

[0110] Other features, advantages and embodiments of the subject matter of the present disclosure disclosed herein will be readily apparent to those exercising ordinary skill after reading the foregoing disclosure. In this regard, while specific embodiments of the subject matter of the present disclosure have been described in considerable detail, variations and modifications of these embodiments can be effected without departing from the spirit and scope of the disclosure as described and claimed.13FR7744-WO-01

Claims

CLAIMSWhat is claimed is:

1. Polyamide composition comprising, based on the total weight of the composition:A) from 30 to 94.87 wt.% of one or more polyamide materials,B) from 5 to 20 wt.% of one or more inorganic white pigment materials, C) from 0.03 to 1.5 wt.% of one or more carbon nanotube materials, and D) from 0.1 to 2.0 wt.% of one or more metal-free organic dyes.

2. The polyamide composition of claim 1 , having(i) a lightness L* of 30 or more in the CIE L*a*b system, determined according to the method described in the experimental section.

3. The polyamide composition of one of the claims 1 or 2, further having(ii) a surface resistivity of 1.0 x 1012Ohm / sq or less, determined according to IEC 62631-3-2.

4. The polyamide composition of claim 3, having(ii) a surface resistivity of 1.0 x 1010Ohm / sq or less, determined according to IEC 62631-3-2.

5. The polyamide composition of one of the claims 3 or 4, having(ii) a surface resistivity of 1.0 x 105Ohm / sq or more, determined according to IEC 62631-3-2.

6. The polyamide composition of one of the previous claims comprising, based on the total weight of the composition, A) from 40 to 87.55 wt.% of one or more polyamide materials.

7. The polyamide composition of one of the previous claims comprising, based on the total weight of the composition, B) from 7 to 15 wt.% of one or more inorganic white pigment materials.14FR7744-WO-018. The polyamide composition of one of the previous claims wherein zinc sulfide constitutes at least 20 wt.% of component B), based on the total weight of component B).

9. The polyamide composition of one of the previous claims comprising, based on the total weight of the composition, C) from 0.05 to 1.0 wt.% of one or more carbon nanotube materials.

10. The polyamide composition of one of the previous claims comprising, based on the total weight of the composition, D) from 0.3 to 1.5 wt.% of one or more a metal-free organic dyes.

11. The polyamide composition of one of the previous claims further comprising, based on the total weight of the composition, F) from 5 to 50 wt.% of one or more filler materials, preferably fibers.

12. The polyamide composition of one of the previous claims wherein component C) comprises single-walled carbon nanotubes.

13. Process for preparing the polyamide composition of one of the previous claims comprising a step a) of simultaneously or sequentially adding to a polyamide material A)B) from 5 to 20 wt.% of one or more inorganic white pigment materials, C) from 0.03 to 1.5 wt.% of one or more carbon nanotube materials, and D) from 0.1 to 2.0 wt.% of one or more metal-free organic dyes, wherein the amounts of components A), B), C) and D) are based on the total weight of the composition.

14. The process of claim 13 comprising:aO) providing an intermediate colorable polyamide composition comprising: A) from 30 to 94.97 wt.% of one or more polyamide materials;B) from 5 to 20 wt.% of one or more inorganic white pigment materials, C) from 0.03 to 1.5 wt.% of one or more carbon nanotube materials, and 15FR7744-WO-01a1) adding from 0.1 to 2.0 wt.% of one or more metal-free organic dyes D) to the colorable polyamide composition, thereby obtaining the polyamide composition.

15. Polyamide product comprising the polyamide composition according to one of the claims 1 to 12, wherein the product is preferably selected from tubing, housing products, shielding products, packaging, films, fabric and sensors.16FR7744-WO-01

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