Aqueous semi-finished and primary non-stick coating compositions comprising aromatic polymers

Abstract

Provided is an aqueous amine-free coating composition including at least one aromatic polymer, wherein the aromatic polymer is in the form of powder having a d.sub.90 less than or equal to 20 μm and in that the aqueous coating composition further includes polar aprotic solvent at a content greater than 0% by weight and less than or equal to 25% by weight. Also provided is an aqueous amine-free non-stick coating composition including such an aqueous composition for a coating, and the respective methods for producing same. Further provided is a method for producing an item on one of the faces of a metal substrate, from at least one layer of the coating composition or one layer of the non-stick coating composition.

Claims

1. An aqueous, amine-free, non-stick coating composition formed over at least one side of a metal substrate, the non-stick coating composition comprising: an aqueous coating composition; at least one fluorocarbon resin; and a non-toxic polar aprotic solvent, wherein a content of the non-toxic polar aprotic solvent in the non-stick coating composition is greater than 0% and less than or equal to 15% by weight, with respect to a total weight of the non-stick coating composition, wherein the aqueous coating composition comprises: at least one aromatic polymer, selected from the group consisting of polyethersulfones (PES), polyether ether sulfones (PEES), polyphenylsulfones (PPSU), polyphenylene sulfides (PPS), polyether ether ketones (PEEK), polyether ketones (PEK), polyether ketone ketones (PEKK), polyether ether ketone ketones (PEEKK), and polyether ketone ether ketone ketones (PEKEKK), and being in powder form with a d.sub.90 of more than or equal to 10 μm and less than or equal to 20 μm; and a polar aprotic solvent, wherein a content of the polar aprotic solvent in the aqueous coating composition is between 0 and 25% by weight, with respect to a total weight of the aqueous coating composition, wherein the non-toxic polar aprotic solvent is N-formylmorpholine (NFM), N-acetylmorpholine (NAM), N-ethylpyrrolidone (NEP) or dimethyl sulfoxide (DMSO).

2. The non-stick coating composition according to claim 1, comprising a maximum of 1% toxic polar aprotic solvent by weight, with respect to the total weight of the non-stick coating composition.

3. The non-stick coating composition according to claim 1, wherein the aqueous coating composition further comprises at least one heterocyclic polymer, which is in powder form with a d.sub.90 diameter of less than or equal to 20 μm, and a relative content of the aromatic polymer, with respect to the heterocyclic polymer in the coating composition, is greater than or equal to 50:50 and less than 100:0.

4. The non-stick coating composition according to claim 3, wherein the at least one heterocyclic polymer is selected from the group consisting of polyimides (PI), polyamide-imides (PAI), polyetherimides (PEI), polyamide-amic acids and mixtures thereof.

5. The non-stick coating composition according to claim 3, wherein a total relative content by weight of the at least one aromatic polymer and the at least one heterocyclic polymer, with respect to the at least one fluorocarbon resin is between 20:80 to 25:75.

6. The non-stick coating composition according to claim 1, wherein a content of the at least one fluorocarbon resin is 30 to 80% by weight, of the total dry weight of the non-stick coating composition.

7. The non-stick coating composition according to claim 1, wherein the non-toxic polar aprotic solvent is NFM or DMSO.

Description

DETAILED DESCRIPTION OF THE INVENTION

Examples

(1) Products

(2) Media Simply degreased, smooth aluminum media

(3) Aqueous Semi-Finished Compositions Polymer resins: Polyphenylene sulfide (PPS) resin, with a degree of polymerization of 100; Polyethersulfone (PES) resin, micronized grade, with a degree of polymerization of greater than 50; Heterocyclic polymer resin: Polyamide-amic acid in aqueous moist powder form with 35.5% dry matter, containing less than 5% N-methylpyrrolidone (NMP) by weight, being of food grade and having a degree of polymerization on the order of 8; Acrylic resin: 30% acrylic polymer solution in aqueous phase; Non-labeled (or in other words, non-toxic, as the term is defined in this invention) polar aprotic solvents: N-formylmorpholine (NFM) Ammonium hydroxide NH.sub.4OH (d=0.9)

(4) Aqueous Primary Compositions Non-labeled (or in other words, non-toxic, as the term is defined in this invention) polar aprotic solvents: N-formylmorpholine (NFM) Labeled (or in other words, toxic, as the term is defined in this invention) polar aprotic solvents: N-ethylpyrrolidone (NEP) Filler: Colloidal silica without surface modification, which has a specific surface of approximately 220 m.sup.2/g, and which is in the form of an aqueous dispersion of nanoparticles with 30% dry matter Carbon black dispersion at 25% dry matter PTFE dispersion at 60% dry matter Alkylphenol ethoxylate-based non-ionic surfactant system at 13% dry matter

(5) Tests

(6) Determining the Dry Matter of an Aqueous Semi-Finished or Primary Composition

(7) Principle

(8) The dry matter of a product is the residual solid portion remaining after evaporation of the volatile materials it contains. The temperature and duration of drying play a major role, as solvents with a high boiling point, monomer fractions, reactive thinners and reaction byproducts (depending on their degree of retention) are very slow to leave the film being formed. It is therefore very important to define, in a very conventional manner, standardized drying conditions that are as close as possible to actual conditions in practice.

(9) Procedure

(10) The procedure to measure this dry matter is as follows: An aluminum dish is weighed: m.sub.0=mass of the dish; 0.5 g to 3 g of the test product is placed in that dish; The filled dish is weighed: m.sub.1=mass of the filled dish; The dish is placed in an oven at 210° C. for two hours; After baking and cooling, the dish is weighed: m.sub.2=mass of the filled dish after baking and cooling; The dry matter is determined by the formula below:
Dry matter=100*[m.sub.2−m.sub.0)/(m.sub.1−m.sub.0)]

(11) Measurement of the Size and Size Distribution of the Particles by Light Diffraction for Powders in Sizes of Between Approximately 100 nm and Approximately 5 mm

(12) After grinding the products in this invention, the ground powder is collected and its particle size is characterized using a laser diffraction particle size analyzer sold under the commercial name Mastersizer by the company Malvern.

(13) Evaluation of the Adhesion of a Semi-Finished or Primary Layer on a Smooth Aluminum Substrate

(14) A cross-cut test is performed in accordance with ISO standard 2409, followed by an immersion of the coated item for 18 hours (consisting of an alternation of three 3-hour cycles in boiling water and three 3-hour cycles in oil at 200° C.). Then, the non-stick coating is observed for signs of detachment.

(15) The rating is as follows: No square must be detached to obtain a rating of 100 (excellent adhesion); In case of detachment, the rating value is equal to the rating of 100 minus the number of detached squares.

(16) Yellowing Evaluation

(17) After baking, the coated plates are evaluated visually for yellowing by comparison between the plates.

(18) Evaluation of the Viscosity Stability of the Semi-Finished and Primary Compositions

(19) This is an evaluation of the stability of the viscosity of the semi-finished and primary compositions applied by spray, in which the flow time is measured according to standard DIN EN ISO 2433/ASTM D5125 using a 2.5-mm flow cup or a 4-mm flow cup.

(20) Viscosity is measured as the continuous flow time, expressed in seconds, of the volume of the flow cup through the calibrated orifice. The flow cup is chosen based on the presumed viscosity of the product.

(21) Change in viscosity is monitored by measuring the continuous flow time of the standardized volume at room temperature directly after the compositions are prepared, and by monitoring the change in this viscosity over time at room temperature.

(22) Once formulated, the compositions are placed in an oven at 40° C.; the change in flow time, and therefore in the viscosity (evaluation of the stability of the emulsion after aging at 40° C.), is then monitored over time.

(23) The semi-finished and primary compositions are evaluated as compliant when they show no signs of settling and have a stable viscosity, or in other words, a viscosity that does not increase by more 20% over two months of storage at room temperature.

(24) Evaluation of the Film Formation Properties of the Semi-Finished and Primary Compositions

(25) The film formation properties of the compositions are related to the corrosion resistance of the layer obtained from said composition. Thus, a composition with good film formation properties will coat the medium perfectly during application and thus provide a layer offering good performance in terms of corrosion.

(26) The corrosion resistance of a coating on a sandblasted aluminum substrate is evaluated by measuring its resistance to the diffusion of salt toward the metal substrate, which corrodes.

(27) The procedure for this is as follows: The substrate is coated with a layer of semi-finished and primary composition according to the examples and comparative examples below; The substrate, thus coated, is immersed for 20 hours in an aqueous saline solution brought to the boiling point (this saline solution comprises 10% sodium chloride by weight. The protocol for this test is the one defined in AFNOR standard NF D21-511 $3.3.5.); After each immersion, a visual inspection is performed of the final appearance of the coating, which consists of noting the presence or absence of signs of corrosion (by a visual observation with the naked eye or with a binocular loupe). In practice, it is a matter of detecting any signs such as blisters with extended areas, or white marks beneath the coating; This observation is followed by a cross-cut test in accordance with ISO standard 2409.

(28) The rating for the cross-cut test is as follows: No square must be detached to obtain a rating of 100 (excellent adhesion); In case of detachment, the rating value is equal to the rating of 100 minus the number of detached squares.

(29) Operating Principle of the Jar Mill (Mechanical Grinding)

(30) Principle

(31) Bead grinding consisting of loading a jar with the sample to be ground and “grinding” beads, and rotating the jar around its axis at a certain speed. The jar is generally rotated by means of a roller machine. The sample can be ground in dry form or dispersed in an appropriate solvent (e.g. in water or alcohol). The dispersion may also contain certain adjuvants (like a dispersing agent or an anti-foaming agent).

(32) Definition of the Main Grinding Parameters

(33) Selection of Grinding Beads (Volume and Diameter(s))

(34) The average diameter of the grinding beads must be appropriate for the size of the particles being ground. The finer the particles, the smaller the diameter of the beads that must be used. The total volume of beads, including the spaces between the beads, will account for approximately 50-60% of the interior volume of the jar. The beads of different sizes are advantageously distributed according to the following proportion by weight, with respect to the total weight of the beads: 25% small beads, 50% medium beads and 25% large beads. The size of the smallest beads is between 2 and 10 mm. Alumina and stabilized zirconia are commonly used as material for the beads.

(35) Volume of Material in the Mill

(36) To limit wear and tear on the grinding beads, the load being ground must cover the load of beads entirely. In general, it will be a volume corresponding to approximately 25% of the volume of the jar.

(37) If the load being ground is a dry powder, the volume of beads will be adjusted after a few minutes of grinding. Because grinding reduces the size of the particles as well as the volume of the spaces between particles, it is necessary to periodically check whether the volume of load being ground is sufficient to cover all of the beads. If this is no longer the case, it is necessary to remove the excess beads to limit contamination of the powder as much as possible.

(38) The duration of the grinding depends on the nature of the polymer resin being ground and on the desired final particle size.

(39) Operating Principle of the Discontimill® Grinding Mill

(40) This grinding is a mechanical grinding that consists of reducing the size of the particles and grains of different types of materials, during which the suspension of the particles and grains is maintained under refrigeration.

(41) The grinding operations are performed with a planetary mill, which consists of a disc, attached to which are two grinding jars, each having a volume of 45 mL and being able to hold up to 7 grinding beads that are 15 mm in diameter. The jars and the grinding beads are made of zirconium oxide, a material known for its very high resistance to impact and wear, enabling grinding for extended durations.

(42) The grinding system operates by rotating the disc holding the jars around their own axes. The rotation speed is the same for the tray and the jars, varying from 100 rev/min to 800 rev/min. However, the directions of rotation are opposite, so as to generate opposing centrifugal forces.

Example 1 of an Aqueous Semi-Finished Composition (SF1)

(43) Preparation of an Aqueous, Amine-Free, Semi-Finished Composition According to the Invention (SF1) with Polar Aprotic Solvent.

(44) An aqueous semi-finished composition (SF1) is produced with the following components, the respective quantities of which are listed below:

(45) TABLE-US-00001 Polyethersulfone (100% dry matter): 119.1 g NFM: 136.0 g Demineralized water: 402.0 g Ammonia: 4.7 g Acrylic resin: 9.0 g TOTAL 670.8 g

(46) To make the aqueous semi-finished composition (SF1), an initial polyethersulfone powder is used, the particle size of which ranges from 20 μm to 10 mm, and more specifically a d.sub.90 of between 40 and 60 μm and a d.sub.50 of between 20 and 40 μm.

(47) Placing the PES in suspension comprises a grinding step, the grinding being done in a Discontimill® brand bead mill at room temperature for a duration ranging from 15 to 30 hours, and preferably 12 to 24 hours, to reduce the size of the PES particles.

(48) The process is as follows: The polyethersulfone powder is placed into the jar; then, The demineralized water and the polar aprotic solvent are added to the mill; Next, the acrylic resin, and then the ammonia are added to the mill; and finally; The grinding step is performed.

(49) The properties of the aqueous composition (SF1) thus obtained are as follows: Theoretical dry matter: 18.2% Dry matter measured in the composition: 18.1% This is a suspension that is opaque white in color. The pH of this composition is between 6 and 7. Viscosity (in a 4-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125) >30 sec: after ageing at 40° C., the composition (SF1) is still stable after 60 days of storage, and the change in viscosity over time is less than 20%. A light diffraction particle sizing measurement using the Mastersizer laser particle size analyzer shows that a main peak is reached at d.sub.50, centered on an average diameter of between 5 and 10 μm and a d.sub.90 of 19 μm, which confirms that all of the powder has been placed in suspension.

Example 2 of an Aqueous Semi-Finished Composition (SF2)

(50) Preparation of an Aqueous, Amine-Free, Semi-Finished Composition (SF2) with Polar Aprotic Solvent.

(51) An aqueous semi-finished composition (SF2) is produced with the following components, the respective quantities of which are listed below:

(52) TABLE-US-00002 Polyethersulfone (100% dry matter): 119.1 g NFM: 100.0 g Demineralized water: 438.0 g Ammonia: 4.7 g Acrylic resin: 9.0 g TOTAL 670.8 g

(53) To produce the aqueous semi-finished composition (SF2), an initial polyethersulfone powder is used, having a particle size ranging from 20 μm to 10 mm, and more specifically, a d.sub.90 of between 40 and 60 μm and a d.sub.50 of between 20 and 40 μm.

(54) Placing the PES in suspension comprises a grinding step, the grinding being done in a Discontimill® brand bead mill at room temperature for a duration ranging from 15 to 30 hours, and preferably 12 to 24 hours, to reduce the size of the PES particles.

(55) The process is as follows: The polyethersulfone powder is placed into the mill; then, The demineralized water and the polar aprotic solvent are added to the mill; Next, the acrylic resin, and then the ammonia are added to the mill; and finally, The grinding step is performed.

(56) The properties of the aqueous composition (SF2) thus obtained are as follows: Theoretical dry matter: 18.2% Dry matter measured in the composition: 18.1% This is a suspension that is opaque white in color. The pH of this composition is between 6 and 7. Viscosity (in a 4-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125) >30 sec: after aging at 40° C., the composition (SF2) is still stable after 60 days of storage, and the change in viscosity over time is less than 20%. A light diffraction particle sizing measurement using the Mastersizer laser particle size analyzer shows that a main peak is reached at d.sub.50, centered on an average diameter of between 5 and 10 μm and a d.sub.90 of 19 μm, which confirms that all of the powder has been placed in suspension.

Example 3 of an Aqueous Semi-Finished Composition (SF3)

(57) Preparation of an Aqueous, Amine-Free, Semi-Finished Composition According to the Invention (SF3) with Polar Aprotic Solvent.

(58) An aqueous semi-finished composition (SF3) is produced with the following components, the respective quantities of which are listed below:

(59) TABLE-US-00003 Polyethersulfone (100% dry matter): 89.3 g Polyphenylene sulfide (100% dry matter): 29.8 g NFM: 100.0 g Demineralized water: 438.0 g Ammonia: 4.7 g Acrylic resin: 9.0 g TOTAL 670.8 g

(60) To produce the aqueous semi-finished composition (SF3), a mixture of polyethersulfone powder and polyphenylene sulfide is used.

(61) Placing this powder mixture in suspension comprises a grinding step, the grinding being done in a Discontimill® brand bead mill at room temperature for a duration ranging from 15 to 30 hours, and preferably 12 to 24 hours, to reduce the size of the particles in the resin mixture.

(62) The process is as follows: The polyethersulfone powder, and then the ammonia, are placed into the mill; then, The polyphenylene sulfide powder is placed into the mill; The demineralized water and the polar aprotic solvent are added to the mill; The acrylic resin is then added to the mill; and finally, The grinding step is performed.

(63) The properties of the aqueous composition (SF3) thus obtained are as follows: Theoretical dry matter: 18.2% Dry matter measured in the composition: 18.3% This is a suspension that is opaque white in color. The pH of this composition is between 6 and 7. Viscosity (in a 4-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125) >30 sec: after ageing at 40° C., the composition (SF3) is still stable after 60 days of storage, and the change in viscosity over time is less than 20%. A light diffraction particle sizing measurement using the Mastersizer laser particle size analyzer shows that a main peak is reached at d.sub.50, centered on an average diameter of 5 to 10 μm and a d.sub.90 of 19 μm, which confirms that all of the powder has been placed in suspension.

Comparative Example 1 of an Aqueous Semi-Finished Composition (SFC1)

(64) Preparation of an aqueous, amine-free, semi-finished composition (SFC1) without polar aprotic solvent, but with a d.sub.90 particle size of greater than 40 μm.

(65) An aqueous semi-finished composition (SFC1) is produced with the following components, the respective quantities of which are listed below:

(66) TABLE-US-00004 Polyethersulfone (100% dry matter): 119.1 g Demineralized water: 624.0 g TOTAL 743.1 g

(67) To produce the aqueous semi-finished composition (SFC1), an initial polyethersulfone powder is used, having a particle size ranging from 20 μm to 10 mm, and more specifically, a d.sub.90 of between 40 and 60 μm and a d.sub.50 of between 20 and 40 μm.

(68) The process is as follows: The polyethersulfone powder is placed into a mixer; then, The demineralized water is added to the mixer; and finally, The mixing step is performed.

(69) The properties of the aqueous composition (SFC1) thus obtained are as follows: Theoretical dry matter: 16.0% Dry matter measured in the composition: 16.3% This is a suspension that is opaque white in color. The pH of this composition is between 6 and 7. The composition obtained (SFC1) settles in less than one day. A light diffraction particle sizing measurement using the Mastersizer laser particle size analyzer shows that a main peak is reached at d.sub.50, centered on an average diameter of approximately 20 μm, as well as a main peak at d.sub.90 centered on an average diameter of approximately 48 μm.

Comparative Example 2 of an Aqueous Semi-Finished Composition (SFC2)

(70) Preparation of an Aqueous, Amine-Free, Semi-Finished Composition (SFC2) with Polar Aprotic Solvent.

(71) An aqueous semi-finished composition (SFC2) is produced with the following components, the respective quantities of which are listed below:

(72) TABLE-US-00005 Polyethersulf one (100% dry matter): 119.1 g NFM: 198.5 g Demineralized water: 344.5 g TOTAL: 662.1 g

(73) To produce the aqueous semi-finished composition (SFC2), an initial powder is used, having a particle size ranging from 20 μm to 10 mm, and more specifically, having a d.sub.90 diameter of between 40 and 60 μm and a d.sub.50 diameter of between 20 and 40 μm.

(74) Placing the PES in suspension comprises a grinding step, the grinding being done in a Discontimill® brand bead mill at room temperature for a duration ranging from 15 to 30 hours, and preferably 12 to 24 hours, to reduce the size of the PES particles.

(75) The process is as follows: The polyethersulfone powder is placed into the mill; then, The demineralized water is added to the mill; The solvent is then added to the mill; and finally, The grinding step is performed.

(76) The properties of the aqueous composition (SFC2) thus obtained are as follows: Theoretical dry matter: 18.0% Dry matter measured in the composition: 18.1% This is a suspension that is opaque white in color. The pH of this composition is between 6 and 7. The composition (SFC2) settles in less than one day. After returning the particles to suspension under mechanical agitation, we observe an apparent increase in viscosity of greater than 20% in less than one week.

Example 4 of an Aqueous Primary Composition According to the Invention (P1)

(77) Preparation of an Aqueous Primary Composition (P1) Made from an Aromatic Polymer-Based, Amine-Free, Semi-Finished Composition without Polar Aprotic Solvent.

(78) An aqueous semi-finished composition is produced with the following components, the respective quantities of which are listed below:

(79) TABLE-US-00006 Polyethersulf one (100% dry matter): 119.1 g Demineralized water: 624.0 g TOTAL: 743.1 g

(80) To produce this aqueous semi-finished composition, an initial polyethersulfone powder is used, having a particle size ranging from 20 μm to 10 mm, and more specifically, a d.sub.90 of between 40 and 60 μm and a d.sub.50 of between 20 and 40 μm.

(81) Placing the PES in suspension comprises a grinding step, the grinding being done in a Discontimill® brand bead mill at room temperature for a duration ranging from 15 to 30 hours, and preferably 12 to 24 hours, to reduce the size of the PES particles.

(82) The process is as follows: The polyethersulfone powder is placed into the mill; then, The demineralized water is added to the mill; and finally, The grinding step is performed.

(83) The properties of this aqueous composition thus obtained are as follows: Theoretical dry matter: 16.0% Dry matter measured in the composition: 16.2% This is a suspension that is opaque white in color. A light diffraction particle sizing measurement using the Mastersizer laser particle size analyzer shows that a main peak is reached at d.sub.50, centered on an average diameter of 5 to 10 μm and a d.sub.90 of 19 μm, which confirms that all of the powder has been placed in suspension.

(84) An aqueous primary composition (P1) for adhesion is produced with the following components, the respective quantities of which are listed below:

(85) TABLE-US-00007 PTFE dispersion:  30.6 g Carbon black dispersion:   5.7 g Semi-finished composition:  33.3 g NFM:  10.0 g Non-ionic surfactant system:   4.8 g Colloidal silica:  12.3 g Demineralized water:   3.3 g TOTAL: 100.0 g

(86) Regarding the non-labeled polar aprotic solvent in the composition (P1), the NFM content is 10.0% by weight, with respect to the total weight of the composition (P1).

(87) The proportion of fluorinated resin in the dry primary composition (P1) in on the order of 63%.

(88) The properties of the primary composition (P1) thus obtained are as follows: Theoretical dry matter in the composition: 29.4% Viscosity (in a 2.5-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125): 45 sec.

Example 5 of an Aqueous Primary Composition According to the Invention (P2)

(89) Preparation of an Aqueous Primary Composition (P2) Based on the Semi-Finished Composition (SF1) in Example 1.

(90) An aqueous primary composition (P2) for adhesion is produced with the following components, the respective quantities of which are listed below:

(91) TABLE-US-00008 PTFE dispersion:  34.1 g Carbon black dispersion:   6.3 g Semi-finished composition SF1  33.4 g (18.2% dry matter):   NFM:   3.3 g Non-ionic surfactant system:   5.3 g Colloidal silica:  13.7 g Demineralized water:   3.9 g TOTAL: 100.0 g

(92) Regarding the non-labeled polar aprotic solvent in the composition (P2), the NFM content is 10.1% by weight, with respect to the total weight of the composition (P2).

(93) The proportion of fluorinated resin in the dry primary composition (P2) is on the order of 63%.

(94) The properties of the primary composition (P2) thus obtained are as follows: Theoretical dry matter in the composition: 32.9% Viscosity (in a 2.5-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125): 51 sec.

Example 6 of an Aqueous Primary Composition According to the Invention (P3)

(95) Preparation of an Aqueous Primary Composition (P3) Based on the Semi-Finished Composition (SF2) in Example 2.

(96) An aqueous primary composition (P3) for adhesion is produced with the following components, the respective quantities of which are listed below:

(97) TABLE-US-00009 PTFE dispersion:  34.1 g Carbon black dispersion:   6.3 g Semi-finished composition SF2  33.4 g (18.2% dry matter):   Non-ionic surfactant system:   5.3 g Colloidal silica:  13.7 g Demineralized water:   7.2 g TOTAL: 100.0 g

(98) Regarding the non-labeled polar aprotic solvent in the composition (P3), the NFM content is 5.0% by weight, with respect to the total weight of the composition (P3).

(99) The proportion of fluorinated resin in the dry primary composition (P3) is on the order of 63%.

(100) The properties of the primary composition (P3) thus obtained are as follows: Theoretical dry matter in the composition: 32.9% Viscosity (in a 2.5-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125): 52 sec.

Example 7 of an Aqueous Primary Composition According to the Invention (P4)

(101) Preparation of an Aqueous Primary Composition (P4) Based on the Aromatic Polymer-Based, Amine-Free, Semi-Finished Composition without Polar Aprotic Solvent, and a Heterocyclic Polymer-Based, Amine-Free, Semi-Finished Composition without Polar Aprotic Solvent.

(102) An aqueous, aromatic polymer-based, semi-finished composition is produced with the following components, the respective quantities of which are listed below:

(103) TABLE-US-00010 Polyethersulf one (100% dry matter): 119.1 g Demineralized water: 624.0 g TOTAL: 743.1 g

(104) This aqueous semi-finished composition is produced using an initial polyethersulfone powder, which has a particle size ranging from 20 μm to 10 mm, and more specifically, a d.sub.90 of between 40 and 60 μm and a d.sub.50 of between 20 and 40 μm.

(105) Placing the PES in suspension comprises a grinding step, the grinding being done in a Discontimill® brand bead mill at room temperature for a duration ranging from 15 to 30 hours, and preferably from 12 to 24 hours, to reduce the size of the PES particles.

(106) The process is as follows: The polyethersulfone powder is placed into the mill; then, The demineralized water is added to the mill; and finally, The grinding step is performed.

(107) The properties of the aqueous composition thus obtained are as follows: Theoretical dry matter: 16.0% Dry matter measured in the composition: 16.2% This is a suspension that is opaque white in color. A light diffraction particle sizing measurement using the Mastersizer laser particle size analyzer shows that a main peak is reached at d.sub.50, centered on an average diameter of 5 to 10 μm and a d.sub.90 of 19 μm, which confirms that all of the powder has been placed in suspension.

(108) An aqueous, heterocyclic polymer-based, semi-finished composition is produced with the following components, the respective quantities of which are listed below:

(109) TABLE-US-00011 Polyamide-amic acid:  616.0 g Demineralized water:  726.3 g TOTAL: 1342.3 g

(110) To make this aqueous semi-finished composition, a 3-liter jar mill system is used to obtain a paste consisting of a stable suspension of polyamide-amic acid particles in water, the final particle size of which is significant for spray coating and obtaining adhesion properties in the resulting coating.

(111) The process is as follows: The polyamide-amic acid powder, the initial particle size of which varies from a few hundred microns to mm, is placed into the jar; then, The demineralized water is added; The jar is kept at room temperature with the mixture thus obtained and the beads on rollers for the duration necessary and sufficient to reduce the size of the polyamide-amic acid particles.

(112) The proportion of toxic polar aprotic solvent in this semi-finished composition, which is NMP, is less than 2.3% by weight, with respect to the total weight of the composition.

(113) The properties of this semi-finished aqueous composition thus obtained are as follows: Theoretical dry matter: 16.3% Dry matter measured in the composition: 16.2% This is a suspension that is creamy white in color. A light diffraction particle sizing measurement using the Mastersizer laser particle size analyzer shows that a main peak is reached at d.sub.50, centered on an average diameter of between 5 and 6 μm and a d.sub.90 of 19 μm, which confirms that all of the powder has been placed in suspension.

(114) Next, an aqueous primary composition (P4) for adhesion is produced with the following components, the respective quantities of which are listed below:

(115) TABLE-US-00012 PTFE dispersion:  30.8 g Carbon black dispersion:   5.7 g Aromatic polymer-based  29.7 g semi-finished composition:   Heterocyclic polymer-based   3.6 g semi-finished composition:   NFM:  10.1 g Non-ionic surfactant system:   4.8 g Colloidal silica:  12.3 g Demineralized water:   3.0 g TOTAL: 100.0 g

(116) Regarding the non-labeled polar aprotic solvent in the composition (P4), the NFM content is 10.1% by weight, with respect to the total weight of the composition (P4).

(117) Regarding the toxic polar aprotic solvents in the composition (P4), the NMP is contained in trace amounts with respect to the total composition (P4) (<0.1%); the NMP comes from the heterocyclic polymer-based semi-finished composition.

(118) The proportion of fluorinated resin in the dry primary composition (P4) is on the order of 63%.

(119) The properties of the primary composition (P4) thus obtained are as follows: Theoretical dry matter in the composition: 29.6% Viscosity (in a 2.5-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125): 51 sec.

Example 8 of an Aqueous Primary Composition According to the Invention (P5)

(120) Preparation of an Aqueous Primary Composition (P5) Based on the Semi-Finished Composition (SF3) in Example 3.

(121) An aqueous primary composition (P5) for adhesion is produced with the following components, the respective quantities of which are listed below:

(122) TABLE-US-00013 PTFE dispersion:  34.1 g Carbon black dispersion:   6.3 g Semi-finished composition  33.4 g SF3 (18.2% dry matter):   Non-ionic surfactant system:   5.3 g Colloidal silica:  13.7 g Demineralized water:   7.2 g TOTAL: 100.0 g

(123) Regarding the non-labeled polar aprotic solvent in the composition (P5), the NFM content is 5.0% by weight, with respect to the total weight of the composition (P5).

(124) The proportion of fluorinated resin in the dry primary composition (P5) is on the order of 63%.

(125) The properties of the primary composition (P5) thus obtained are as follows: Theoretical dry matter in the composition: 33.0% Viscosity (in a 2.5-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125): 51 sec.

Example 9 of an Aqueous Primary Composition According to the Invention (P6)

(126) Preparation of an Aqueous Primary Composition (P6) Based on the Semi-Finished Composition (SF3) in Example 3 and a Heterocyclic Polymer-Based Semi-Finished Composition.

(127) An aqueous, heterocyclic polymer-based, semi-finished composition is produced with the following components, the respective quantities of which are listed below:

(128) TABLE-US-00014 Polyamide-amic acid:  616.0 g Demineralized water:  726.3 g TOTAL: 1342.3 g

(129) To make this aqueous semi-finished composition, a 3-liter jar mill system is used to obtain a paste consisting of a stable suspension of polyamide-amic acid particles in water, the final particle size of which is significant for spray coating and obtaining adhesion properties in the resulting coating.

(130) The process is as follows: The polyamide-amic acid powder, the initial particle size of which varies from a few hundred microns to mm, is placed into the jar; then, The demineralized water is added; The jar is kept at room temperature with the mixture thus obtained and the beads on rollers for the duration necessary and sufficient to reduce the size of the polyamide-amic acid particles.

(131) The proportion of toxic polar aprotic solvent in this semi-finished composition, which is NMP, is less than 2.3% by weight, with respect to the total weight of the composition.

(132) The properties of this semi-finished aqueous composition thus obtained are as follows: Theoretical dry matter: 16.3% Dry matter measured in the composition: 16.2% This is a suspension that is creamy white in color. A light diffraction particle sizing measurement using the Mastersizer laser particle size analyzer shows that a main peak is reached at d.sub.50, centered on an average diameter of between 5 and 6 μm and a d.sub.90 of 19 μm, which confirms that all of the powder has been placed in suspension.

(133) Next, an aqueous primary composition (P6) for adhesion is produced with the following components, the respective quantities of which are listed below:

(134) TABLE-US-00015 PTFE dispersion:  34.1 g Carbon black dispersion:   6.3 g Semi-finished composition SF3  30.0 g (18.2% dry matter): Heterocyclic polymer-based   4.1 g semi-finished composition: NFM:   1.0 g Non-ionic surfactant system:   5.3 g Colloidal silica:  13.7 g Demineralized water:   5.5 g TOTAL: 100.0 g

(135) Regarding the non-labeled polar aprotic solvent in the composition (P6), the NFM content is 5.5% by weight, with respect to the total weight of the composition (P6).

(136) Regarding the toxic polar aprotic solvent in the composition (P6), the NMP is contained in trace amounts with respect to the total composition (P6) (<0.1%); the NMP comes from the heterocyclic polymer-based semi-finished composition.

(137) The proportion of fluorinated resin in the dry primary composition (P6) is on the order of 62%.

(138) The properties of the primary composition (P6) thus obtained are as follows: Theoretical dry matter in the composition: 32.9% Viscosity (in a 2.5-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125): 50 sec.

Comparative Example 3 of an Aqueous Primary Composition (PC1)

(139) Preparation of an Aqueous Primary Composition (PC1) Based on an Aromatic Polymer-Based, Amine-Free, Semi-Finished Composition without Polar Aprotic Solvent.

(140) An aqueous primary composition (PC1) for adhesion is produced with the following components, the respective quantities of which are listed below:

(141) TABLE-US-00016 PTFE dispersion:  30.6 g Carbon black dispersion:   5.7 g Semi-finished composition:  33.3 g Non-ionic surfactant system:   4.8 g Colloidal silica:  12.3 g Demineralized water:  13.3 g TOTAL: 100.0 g

(142) The proportion of fluorinated resin in the dry primary composition (PC1) is on the order of 63%.

(143) The properties of the primary composition (PC1) thus obtained are as follows: Theoretical dry matter in the composition: 29.4% Viscosity (in a 2.5-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125): 48 sec.

Comparative Example 4 of an Aqueous Primary Composition (PC2)

(144) Preparation of an Aqueous Primary Composition (PC2) Based on the Semi-Finished Composition (SFC1) in Comparative Example 1.

(145) An aqueous primary composition (PC2) for adhesion is produced with the following components, the respective quantities of which are listed below:

(146) TABLE-US-00017 PTFE dispersion:  30.6 g Carbon black dispersion:   5.7 g Semi-finished composition SFC1  33.3 g (16.0% dry matter):   NFM:  11.0 g Non-ionic surfactant system:   4.8 g Colloidal silica:  12.3 g Demineralized water:   2.3 g TOTAL: 100.0 g

(147) Regarding the non-labeled polar aprotic solvent in the composition (PC2), the NFM content is 11.0% by weight, with respect to the total weight of the composition (PC2).

(148) The proportion of fluorinated resin in the dry primary composition (PC2) is on the order of 63%.

(149) The properties of the primary composition (PC2) thus obtained are as follows: Theoretical dry matter in the composition: 29.5% Viscosity (in a 2.5-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125): 48 sec.

Comparative Example 5 of an Aqueous Primary Composition (PC3)

(150) Preparation of an Aqueous Primary Composition (PC3) Based on the Semi-Finished Composition (SFC2) in Comparative Example 2.

(151) An aqueous primary composition (PC3) for adhesion is produced with the following components, the respective quantities of which are listed below:

(152) TABLE-US-00018 PTFE dispersion:  29.7 g Carbon black dispersion:  5.5 g Semi-finished composition SFC2  28.6 g.sup.1 (18.0% dry matter):   NFM:  17.7 g Non-ionic surfactant system:  4.6 g Colloidal silica:  11.9 g Dem ineralized water:  2.0 g TOTAL: 100.0 g

(153) Regarding the non-labeled polar aprotic solvent in the composition (PC3), the NFM content is 26.3% by weight, with respect to the total weight of the composition (PC3).

(154) The proportion of fluorinated resin in the dry primary composition (PC3) is on the order of 63%.

(155) The properties of the primary composition (PC3) thus obtained are as follows: Theoretical dry matter in the composition: 28.5% Viscosity (in a 2.5-mm flow cup according to standard DIN EN ISO 2433/ASTM D5125): 47 sec.

(156) Results of the Tests Performed

(157) The semi-finished and primary compositions described above are listed in Tables 1 and 2 below.

(158) The primary compositions are evaluated for their stability in terms of viscosity.

(159) The coatings obtained from these various compositions are subject to adhesion testing of the primary composition on the substrate, to the coloration test and to the corrosion resistance test. The primary compositions according to the invention have been observed to be stable over time and make it possible to obtain corrosion-resistant coatings; therefore, these primary compositions offer good film formation properties.

(160) The coloration of the coating, evaluated visually, makes it possible to verify that the formulas produced according to the invention show acceptably little to no yellowing in comparison to the traditional formulations that include Lewis bases.

(161) Coating adhesion is ensured when the size of the powder is compliant with the invention.

(162) TABLE-US-00019 TABLE 1 SEMI-FINISHED Semi-finished composition SF3 and PAA — SF1 SF2 — SF3 powder — Ex. 1 Ex. 2 — Ex. 3 Ex. 3 Resin type PES powder PES powder PES powder PAI + PES PES and PPS PES, PPS and powder powder PAI powder Amine type 0 0 0 0 0 0 Resin particle size d.sub.90 < 20 μm d.sub.90 < 20 μm d.sub.90 < 20 μm d.sub.90 < 20 μm d.sub.90 < 20 μm d.sub.90 < 20 μm d.sub.50 < 10 μm d.sub.50 < 10 μm d.sub.50 < 10 μm d.sub.50 < 10 μm d.sub.50 < 10 μm d.sub.50 < 10 μm Polar aprotic solvent 0 NFM = 20.3% NFM = 14.9% NMP < 2.3% NFM = 14.9% NFM = 14.9% in PAI in SF5 and NMP < 2.3% PRIMARY Primary composition P1 P2 P3 P4 P5 P6 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Labeled polar aprotic 0 0 0 NMP < 0.1% 0 NMP < 0.1% solvent Non-labeled polar NFM = 10.0% NFM = 10.1% NFM = 5.0% NFM = 10.1% NFM = 5.0% NFM = 5.5% aprotic solvent Primary labeling NO NO NO NO NO NO TESTS Coating coloration None None None Very slight Very slight Very slight yellowing yellowing yellowing Adhesion test on Excellent Excellent Excellent Excellent Excellent Excellent smooth Al substrate Stability Compliant Compliant Compliant Compliant Compliant Compliant Corrosion resistance Compliant Compliant Compliant Compliant Compliant Compliant (rated 100) (rated 100) (rated 100) (rated 100) (rated 100) (rated 100)

(163) TABLE-US-00020 TABLE 2 Semi-finished SEMI-FINISHED composition — SFC1 SFC2 — Comp. Ex. 1 Comp. Ex. 2 Resin type PES powder PES powder PES powder Amine type 0 0 0 Resin particle size d.sub.90 < 20 μm d.sub.90 < 20 μm d.sub.90 < 20 μm d.sub.50 < 10 μm d.sub.50 < 10 μm Polar aprotic solvent 0 0 NFM = 30.0% PRIMARY Primary composition PC1 PC2 PC3 Comp. Ex. 3 Comp. Ex. 4 Comp. Ex. 5 Labeled polar aprotic 0 0 0 solvent Non-labeled polar 0 NFM = 11.0% NFM = 26.3 aprotic solvent Primary labeling NO NO NO TESTS Coating coloration None None None Adhesion test on Poor Poor Poor smooth Al substrate Stability Non- Non- Non- compliant compliant compliant Corrosion resistance Very poor Compliant Very poor (rated 0) (rated 100) (rated 0)