EP1985377B1 - Painted plastic material part and method for painting such a part - Google Patents

Abstract

The process for painting a part (10) of fiber-reinforced plastic material e.g. sheet molding compound, comprises coating a surface (14) of the part with a primer coat (16), coating the primer coat with a lacquer coat (18) for revealing defect, inspecting the lacquer coat for detecting any defects, and coating the lacquer coat with a paint coat (19) providing a final finish to the part if any defect is not detected. If any defect is detected, then the process further comprises repairing an area comprising the defect, and coating the defect area by a second primer coat. The process for painting a part (10) of fiber-reinforced plastic material e.g. sheet molding compound, comprises coating a surface (14) of the part with a primer coat (16), coating the primer coat with a lacquer coat (18) for revealing defect, inspecting the lacquer coat for detecting any defects, and coating the lacquer coat with a paint coat (19) providing a final finish to the part if any defect is not detected. If any defect is detected, then the process further comprises repairing an area comprising the defect, coating the defect area by a second primer coat and then coating the second primer coat of a second lacquer coat, and coating the second lacquer coat for revealing defect with the paint providing a finish to the part. The lacquer coat is either coated with a lacquer finish coat or a base coat and then with a varnish finish. The primer coat is coated with the lacquer coat after a desolvatation step of the primer coat and before hardening the primer coat. The primer coat and the lacquer coat are simultaneously hardened at a first hardening temperature (T 1). The part is heated at a second temperature (T 2) to harden the paint coat, where T 2is greater than T 1. The hardened lacquer coat has a luster of 55-65 units of brightness, and a thickness of 20-30 mm. An independent claim is included for a painted plastic part.

Description

The present invention relates to the painting of plastic parts.

It applies, in particular but not exclusively, to plastic parts reinforced with fibers, for example in SMC, BMC, AMC material coated or not with IMC, respectively acronyms for the English expressions "Sheet Molding Compound", " Bulk Molding Compound "," Advanced Molding Compound "and" InMold Coating ".

It is known to prime a surface of a part to be painted by coating it with one or more layers of a primer. This primer has the function of regularizing the surface of the part which generally comprises surface porosities, in the form of holes whose general dimensions vary from a few microns up to the millimeter. The primer allows on the one hand to fill these porosities and on the other hand, to create a layer of adhesion for the next layer, for example a layer of paint. This layer of paint is, for example, composed of one or more layers comprising a base and a varnish.

However, once the parts are painted, imperfections may occur, which forces the parts to be returned.

The document DE10156477 teaches application of a primer layer to a plastic part, a coating of defect lacquer, a layer of adhesion primer, and a final coat of paint.

The invention aims to reduce the rate of parts to resume.

• on revêt une surface de la pièce d'une couche d'un apprêt ;
• on revêt la couche d'apprêt d'une couche d'une laque de révélation de défauts ;
• on inspecte la couche de laque de révélation de défauts pour y détecter d'éventuels défauts révélés ;
• dans le cas où l'on ne détecte pas d'éventuels défauts, on revêt la couche de laque de révélation de défauts d'une couche de peinture conférant à la pièce son aspect final.

The invention relates to a method for painting a plastic part, characterized in that, during this process:

• one surface of the part is coated with a layer of a primer;
• the primer is coated with a layer of a defect lacquer;
• the defect lacquer layer is inspected for possible revealed defects;
• in the case where no defects are detected, the coating layer of defect lacquer is coated with a layer of paint giving the piece its final appearance.

It will include "lacquer" in the sense of the skilled person, that is to say in the sense of a chemical composition intended initially to be used as a topcoat, with or without pigments, these pigments being intended to form a visible outer shade of the room. Thus, generally, a lacquer has a high gloss unlike a primer that is generally dull. In addition, a primer generally has a low surface tension and forms a ductile layer. On the contrary, a lacquer has a higher surface tension and forms a film. In addition, a primer generally forms a porous layer while a lacquer forms a substantially watertight film.

The term "primer" will be understood to mean a chemical composition intended in particular to form a layer of porosity filling, of adhesion for the next layer and which does not form a visible outer layer of the part.

The gloss, surface tension and sealing properties of the lacquer make it possible to detect microporosity filling defects. By "filling", one will understand the capacity of a layer to fill a microporosity, but also its capacity to cover it without necessarily filling it. Indeed, it is surprising to see that the shiny and taut appearance of the lacquer layer discriminates between areas without defects and areas with defects. Thus, the defect areas have a different brightness and tension than the areas without defects, which reveals the microporosity imperfectly filled by the primer layer.

Lacquer revealing any microporosity imperfectly filled by the primer, it can detect a lack of filling microporosities before the application of the paint layer. It is then possible to remedy the nonconformity of the part. The rate of non-compliant parts is then reduced by detecting them before the application of the paint layer.

Moreover, the painting being expensive, the method according to the invention also makes it possible to reduce the cost generated by the use of paint, in particular by the use of colored pigments, on parts which, in the state of the art, it would have detected non-compliant only after application of the paint.

Another advantage of the process according to the invention is that the application of the revelatory lacquer makes it possible to fill in some of the microporosities imperfectly filled by the primer. Indeed, the lacquer has microporosity filling properties, which makes it unnecessary, in some cases, repair microporosity imperfectly filled by the primer.

Such a method is also advantageous because the coating layer has good adhesion properties so that the paint layer can be applied directly to the coating layer of revelation without the need to apply a layer of paint. intermediate primer which would be essential for the adhesion of the paint layer.

In addition, the surface tension of the revelation lacquer layer being high, the paint layer has an excellent tension. It will be understood by "stretched" the ability of the paint to spread over the layer of revelation lacquer so as to form a homogeneous surface.

The paint layer gives the final appearance of the piece, including its color and / or gloss.

Thus, the layer of revelation lacquer has a quadruple function. Firstly, the revelation lacquer layer makes it possible to detect the microporosities imperfectly filled by the primer layer. Then, the layer of revelation lacquer, by its microporosity filling properties allows, in some cases, to avoid a recovery of the room. In addition, the coating layer of revelation, because of its adhesion properties, forms a satisfactory adhesion layer so that one directly applies the paint layer on the lacquer layer. Finally, thanks to its high surface tension, the revelation lacquer layer allows a better tension of the paint layer than the tension allowed by the primer layer.

• on répare une zone comprenant le défaut ;
• on revêt la zone comprenant le défaut d'une seconde couche d'apprêt, puis on revêt la seconde couche d'apprêt d'une seconde couche de laque de révélation de défauts ;
• on revêt la seconde couche de laque de révélation de défauts de la couche de peinture conférant à la pièce son aspect final.

According to an optional characteristic of the method according to the invention, in the case where a possible defect is detected:

• an area including the defect is repaired;
• coating the defect area with a second primer layer, and coating the second primer layer with a second defect lacquer coating layer;
• the second layer of defect lacquer is coated with the paint layer giving the piece its final appearance.

In the case where the microporosity filling properties of the lacquer do not make it possible satisfactorily to fill this microporosity and where a microporosity is detected, the area comprising the defect is repaired, for example by filling this offending zone.

Then, the area is covered and thus the defect of a second layer of primer. This second primer is intended to fill the microporosity imperfectly filled by the first layers of primer and lacquer that we would not have repaired. The second coat of primer is then coated with the second coat of revelation lacquer. This second layer of revelation lacquer makes it possible to ensure that all the microporosities detected by the application of the first layer of revelation lacquer have been filled.

Another advantage of such a method is that it makes it possible to carry out two applications of the primer and the reveling lacquer in the same manufacturing facility, the primer and the revelation lacquer being able to be the same at the first time. and the second applications.

Advantageously, the revelation lacquer layer is coated with the layer of paint by coating the revelation lacquer layer with either a layer of an appearance lacquer or a base appearance layer and then a coating layer of varnish.

An "appearance lacquer layer" will be understood to mean a layer intended to be seen by an observer of the room. On a body part, such a layer of appearance lacquer is usually called "your body".

The layers of basic appearance and varnish also form a so-called "tone box" layer but generally give the painted part a final appearance aesthetically more advantageous than that conferred by the appearance of the lacquer, especially in terms of color, gloss and depth.

In one embodiment of the process according to the invention, the primer layer is coated with the defect-clearing lacquer layer after a step of desolvating the primer layer and prior to curing the primer layer.

The term "desolvation step" will be understood to mean a step during which solvent evaporation is carried out and, possibly, partial hardening of the primer layer.

It will be understood by "curing" the primer layer of substantially completely curing the primer layer.

This desolvation step is then sufficient to allow the application of the defect coating layer to the uncured primer layer. The so-called "wet wet" defect lacquer layer is then applied, which refers to the fact that the non-fully cured primer layer is directly coated with the developer lacquer layer. .

This embodiment makes it possible to avoid completely hardening the primer layer before applying the revelation lacquer layer. It also makes it possible to simultaneously harden the layers of primer and revealing lacquer during a single step of cooking the piece to be painted.

Advantageously, the uncoated primer layer and the developer lacquer layer are simultaneously cured at a first curing temperature and the workpiece is heated to a second temperature to cure the paint layer, the second temperature being generally greater than the first temperature. .

It is common practice to use a second temperature for curing the paint which is higher than the first temperature used for the curing of the primer and developer layers. The coating layer of lacquer forming, once cured, a substantially impermeable film, it is possible to harden the paint layer regardless of its curing temperature while ensuring that the piece will not include any surface defects. It will be noted that the curing temperature of the paint remains within the thermal stability limits of the material constituting the part, the primer and the lacquer.

According to another embodiment, the primer is cured and then the lacquer layer is cured and then the paint layer is cured.

According to another optional feature of the process according to the invention, the brightness of the hardened coating layer is between 50 and 90 gloss units, or even between 50 and 70 gloss units and preferably between 55 and 65 gloss units.

Such gloss is advantageous for revealing microporosity filling defects. Thus, too low gloss will not easily discriminate areas of defects and areas with no defects. On the contrary, too high gloss will reveal other surface irregularities that will not easily discriminate microporosity filling defects.

According to another optional feature of the process according to the invention, the revelatory lacquer is of the polyurethane type.

Such a lacquer is easy to implement and cheap.

• (A) un composé comprenant au moins deux atomes donneurs d'hydrogène par molécule de ce composé;
• (B) un composé comprenant au moins deux fonctions isocyanates par molécule de ce composé.
• (C) des éventuels additifs.

By way of example, a polyurethane lacquer is obtained from a mixture of the following three constituents:

• (A) a compound comprising at least two hydrogen donor atoms per molecule of this compound;
• (B) a compound comprising at least two isocyanate functional groups per molecule of this compound.
• (C) possible additives.

The compound (A) is, for example, chosen from the group comprising polyols, polyamines, ureas, polyamides, polyesterols, polyetherols, their salts or their mixtures.

Advantageously, the compound (A) comprises trialkyls and / or triamines. Such compounds (A) generally make it possible to obtain a thermosetting polyurethane lacquer.

Advantageously, the compound (B) is chosen from aliphatic polyisocyanates so that the polyurethane lacquer is a copolymer of one or more aliphatic polyisocyanates.

Additives (C) include, for example, glycols, aminoalcohols, aromatic amines or even carboxylic acids.

According to another optional feature of the process according to the invention, the thickness of the coating layer of revelation is between 15 and 35 microns, or even 15 and 30 microns and preferably between 20 and 30 microns.

Thus, thanks to such a method, it is possible to reduce the amount of primer used for each piece. Indeed, the layer of revelation lacquer allowing the direct application of the paint layer on itself, it is possible to use a smaller amount of primer so that a thickness of the bilayer primer and lacquer revelation according to the invention is substantially equal to a thickness of a primer layer applied according to a method of the state of the art.

• une couche d'un apprêt revêtant une surface de la pièce ;
• une couche d'une laque de révélation de défauts revêtant la couche d'apprêt ;
• une couche de peinture revêtant la couche de laque de révélation de défauts.

The subject of the invention is also a painted plastic part characterized in that it comprises:

• a layer of a primer coating a surface of the room;
• a layer of a defect coating lacquer coating the primer;
• a layer of paint coating the lacquer coating of defects.

The paint layer gives the final appearance of the piece, including its color and / or gloss.

Advantageously, the part comprises a plastic material reinforced with fibers, for example SMC, BMC, AMC coated or not with IMC.

A molded sheet generally has a high rigidity but also a rough surface comprising many microporosities. The coating layer of revelation is therefore particularly suitable and advantageous in the case of the detection of microporosity filling defects of such a part.

• la figure 1 est une vue partielle en coupe d'une pièce peinte selon un mode de réalisation de l'invention comprenant une microporosité, cette microporosité étant recouverte par des couches d'apprêt, de laque de révélation et de peinture;
• la figure 2 est une vue partielle en coupe de la pièce peinte de la figure 1 avant application de la couche de peinture;
• la figure 3 est une variante de la pièce à peindre de la figure 2 dans laquelle la microporosité est recouverte uniquement par la couche de laque ;
• la figure 4 est une vue de la pièce apprêtée de la figure 3 non revêtue de la couche de laque;
• la figure 5 est une vue de la pièce apprêtée de la figure 4 revêtue de la couche de laque et dans laquelle la microporosité n'est pas recouverte par la couche de laque;
• la figure 6 est une vue de la pièce de la figure 5 après réparation d'un défaut.

The invention will be better understood on reading the description which will follow, given solely by way of nonlimiting example and with reference to the drawings in which:

• the figure 1 is a partial sectional view of a painted part according to an embodiment of the invention comprising a microporosity, this microporosity being covered by layers of primer, revelation lacquer and paint;
• the figure 2 is a partial sectional view of the painted piece of the figure 1 before application of the paint layer;
• the figure 3 is a variant of the piece to paint the figure 2 in which the microporosity is covered only by the lacquer layer;
• the figure 4 is a view of the primed piece of the figure 3 not coated with the lacquer layer;
• the figure 5 is a view of the primed piece of the figure 4 coated with the lacquer layer and in which the microporosity is not covered by the lacquer layer;
• the figure 6 is a view of the room from the figure 5 after repairing a defect.

We have shown on the figure 1 a part of a painted plastic part and designated by the general reference 10.

The painted part 10 is made of a plastic material M reinforced with fibers, for example SMC coated with IMC. This material may in particular be obtained by crosslinking a thermosetting resin filled with glass fibers, for example a resin comprising an unsaturated polyester. Part 10 is, for example, an automobile bodywork part such as a hood, a front grille, a roof or a bumper.

The part 10 comprises a porosity 12 present on a surface 14 of the part 10. The average overall size of the porosity varies from a few microns to a millimeter. In the example shown on the Figures 1 to 6 porosity 12 has an average overall size of about 50 microns.

The part 10 comprises a layer 16 of a primer coating the surface 14 of the part 10. The part also comprises a layer 18 of a defect-revealing lacquer coating the primer layer 16.

The part 10 also comprises a layer of paint 19 coating the layer of lacquer 18 of revelation.

For example, the primer used is of the polyurethane type. The primer is applied to the surface 14 in the form of a composition comprising a base, a hardener and a diluent. This composition comprises about 10 mass units of the hardener, 10 to 20 mass units of the diluent per 100 mass units of the base. The base comprises a resin, fillers, pigments of the additives and solvents respectively in proportions varying between 30 and 35%, 25 and 30%, 10 and 15%, 2 and 5%, 25 and 30%. The hardener is, for example, an aliphatic polyisocyanate.

In the embodiment described, the lacquer used is of the polyurethane type. The lacquer is applied to the primed surface in the form of a composition comprising a base, a hardener and a diluent. This composition comprises about 22 hardener mass units, 16 mass units of the diluent per 100 mass units of the base. The base comprises a resin, fillers, pigments, additives and solvents respectively in proportions varying between 45 and 50%, 0 and 5%, 25 and 30%, 2 and 5%, 20 and 25%. The hardener is, for example, a mixture of one or more aliphatic polyisocyanates so that once cured, the lacquer forms a copolymer of one or more aliphatic polyisocyanates.

In the example shown on the Figures 1, 2 and 3 the primer and lacquer have beige and gray-white satin shades respectively.

The main aspects of the process for preparing the workpiece 10 will now be described.

First, the surface 14 of the primer layer 16 is coated as shown in FIG. figure 4 . According to a first embodiment, the hardening of the primer layer 16 is caused, for example, by heating the workpiece.

On the figure 4 the microporosity 12 is neither filled with the primer nor covered by the primer 16 coating the surface 14. The microporosity 12 contains no solvent, the solvents of the composition intended to form the primer being evaporated during the curing of the primer layer 16 under the effect of temperature.

After having coated the surface 14 of the primer layer 16, the primer layer 16 is coated with the lacquer layer 18, as shown in FIGS. figures 3 and 5 .

On the figure 3 , the lacquer layer 18 covers the microporosity 12, while on the figure 5 the lacquer layer 18 does not cover the microporosity 12.

This layer of lacquer 18 is applied so that the thickness of this layer 18 is between 15 and 35 microns. The thickness may also be between 15 and 30 microns and preferably between 20 and 30 microns. In this case, the primer 16 and lacquer 18 are applied using automated painting means, such as a robotic arm equipped with a paint sprayer.

Then, in this first embodiment, the part is heated so as to cause the hardening of the lacquer layer 18.

In order to detect a possible lack of filling of the microporosity 12, the lacquer layer 18 is inspected.

By exposing the part coated with the lacquer layer 18 to a light, for example a substantially white artificial light, it is easy to detect the lack of filling of the microporosity 12.

By way of example, the detection is carried out with the human eye. It is also possible to use automated detection means such as, for example, an automaton sweeping the lacquer layer 18 of the part 10. This automaton is, in particular, provided with means for measuring the gloss of the lacquered surface, for example a glossmeter. The brightness measured on the hardened lacquer layer 18 is then between 50 and 90 gloss units. This gloss may optionally be between 50 and 70 gloss units and preferably between 55 and 65 gloss units. In the example, the brightness is measured at an angle of 20 degrees.

This detection is made possible by the lacquer layer 18 which makes it possible to discriminate a zone 24 of the lacquer layer 18, located at the right of the imperfectly filled microporosity 12, with respect to another zone 26 of the lacquer layer 18 which does not exhibit no microporosity to his right, as shown on the figure 5 .

Thus, for example, the reflection of an incident ray 28 on the zone 24 generates a reflected ray 30 of a different nature from that of a reflected ray 32 generated by the reflection of an incident ray 34 on the zone 26.

In the case shown in figure 2 , in which the primer layer 16 covers the microporosity 12, no filling defect is detected. Indeed, all the incident rays 28 are reflected in the same way by the revelation lacquer layer 18.

In the case shown in figure 3 , although the primer layer 16 does not cover the microporosity 12, it is not detected, either, lack of filling. In fact, in this case, the filling property of the lacquer layer 18 is used. In a similar manner to the case shown in FIG. figure 2 all the incident rays 28 are reflected in the same way by the revelation lacquer layer 18.

On the figure 6 after detection of the defect, the zone 24 comprising the microporosity 12 is repaired. In this case, the layers 16 and 18 are removed using conventional means, for example using a sander.

Then, the defect is correctly filled with a conventional composition, for example a coating or a putty E.

Areas 24 and 26 are then coated with a second primer layer 36. Next, this second primer layer 36 is coated with a second layer of revelation lacquer 38 to ensure that the microporosity has been removed. correctly filled with the coating E.

When the lacquer layer 38 is inspected and any defect is not detected, the lacquer layer 38 is coated with the paint layer 19 giving the part 10 its final appearance, in particular its final color.

This paint layer 19 comprises, in the example described, a lacquer appearance.

Alternatively, the lacquer layer 38 is coated with a base appearance layer, followed by a lacquer coating layer. This bilayer then forms the layer of paint 19.

In the case of a thermosetting paint, the part is then heated to harden the paint.

It should be noted that in the event that any defects are not detected after inspection of the first layer of revelation lacquer 18 as is shown in FIGS. Figures 2 and 3 , after curing of the primer layers 16 and lacquer 18, the paint layer 19 imparts to the part 10 its final appearance without performing any repair.

In a second embodiment, the primer layer 16 is coated with the defect-proofing lacquer layer 18 after a step of desolvating the primer layer 16 and prior to the hardening of the primer layer 16.

Thus, after having coated the part 10 with the lacquer layer, the solvents of the primer layer 16 are evaporated during the stage of desolvation. In this step, it causes only a partial hardening of the primer layer 16, unlike the previous embodiment where it cures the entire primer layer.

Then, the primer coat 16 is coated with the lacquer layer 18.

Finally, the uncoated primer layer 16 and the developer coating layer 18 are simultaneously cured at a first cure temperature T ₁ .

After application of the paint layer 19 to coat the layer of revelation lacquer 18, the piece 10 is heated to a second temperature T ₂ to harden the paint layer 19. This second temperature T ₂ is then generally greater than the first temperature T ₁ .

It will be noted that this second embodiment also applies to the second layers of primer and lacquer in the case of detecting a possible defect, after the application of the first layers of primer and lacquer, and where the the area containing the defect must be repaired.

Among the advantages of the method according to the invention, it will be noted that it makes it possible to detect defects in the cases where the manufacturing method of the part generates a large number of porosities. Thus, the method according to the invention is particularly relevant in the case where the part is manufactured at low temperature and low pressure.

The invention is not limited to the embodiments described.

Thus, the surface 14 of the plastic part 10 may have undergone various prior chemical or physicochemical surface treatments prior to the application of the primer layer 16.

In addition, the invention may also be applied to a BMC-type part of the English wording "Bulk Molding Compound" or any other type of plastic part, reinforced or not by fibers.

In addition, as in the case shown in figure 4 where the primer layer 16 does not cover the microporosity 12 imperfectly filled, the lacquer layer 18 can penetrate the microporosity 12 and thus fill it.

Note also that the primer used may not be thermosetting. This type of non-thermosetting primer will be used, in particular, for preparing thermoplastic material parts.

Finally, it will be noted that, in accordance with the method according to the invention, it is possible to coat a surface 14 of the part 10 already treated or already coated with any layer, without departing from the scope of the invention.

Claims (12)

1. A method of painting a plastics-material part (10), the method being characterized by:

   · coating a surface (14) of the part in a primer layer (16);

   · directly coating the primer layer (16) in a layer of a fault-revealing lacquer (18);

   · inspecting the layer of fault-revealing lacquer (18) in order to detect any faults therein; and

   · in the event that no faults are detected, directly coating the layer of fault-revealing lacquer (18) in a layer of paint (19) conferring its final appearance to the part (10).
2. A method according to claim 1, wherein, in the event of detecting a fault, the following steps are performed:

   · repairing a zone (24) including the fault;

   · coating the zone (24) including the fault in a second layer of primer (36) and then directly coating the second layer of primer (36) in a second layer of fault-revealing lacquer (38); and

   · directly coating the second layer of fault-revealing lacquer (38) in the layer of paint (19) conferring its final appearance to the part (10).
3. A method according to claim 1 or claim 2, in which the layer of fault-revealing lacquer (18, 38) is coated directly with the layer of paint (19) by coating the layer of fault-revealing lacquer (18, 38) either directly with a layer of an appearance lacquer, or directly with an appearance base layer followed by a layer of appearance varnish.
4. A method according to any one of claims 1 to 3, wherein the primer layer (16, 36) is coated in the layer of fault-revealing lacquer (18, 38) after a step of extracting solvent from the primer layer (16, 36) and before hardening of the primer layer (16, 36).
5. A method according to claim 4, wherein the solvent-extracted primer layer (16, 36) and the layer of fault-revealing lacquer (18, 38) are hardened simultaneously at a first hardening temperature (T₁), and the part (10) is heated to a second temperature (T₂) to harden the layer of paint (19), the second temperature (T₂) generally being higher than the first temperature (T₁).
6. A method according to any one of claims 1 to 3, wherein the primer layer (16, 36) is hardened, and then the layer of lacquer (18, 38) is hardened, and then the layer of paint (19) is hardened.
7. A method according to any preceding claim, wherein the gloss of the layer of hardened lacquer (18, 38) lies in the range 50 to 90 gloss units, or in the range 50 to 70 gloss units, and preferably in the range 55 to 65 gloss units.
8. A method according to any preceding claim, wherein the fault-revealing lacquer is of the polyurethane type.
9. A method according to claim 8, wherein the polyurethane lacquer is a copolymer of one or more aliphatic polyisocyanates.
10. A method according to any preceding claim, wherein the thickness of the layer of fault-revealing lacquer lies in the range 15 µm to 35 µm, or in the range 15 µm to 30 µm, and preferably in the range 20 µm to 30 µm.
11. A painted part (10) of plastics material, the part being characterized in that it includes:

    · a primer layer (16, 36) coating a surface (14) of the part (10);

    · a layer of fault-revealing lacquer (18, 38) directly coating the primer layer (16, 36); and

    · a layer of paint (19) directly coating the layer of fault-revealing lacquer (18, 38).
12. A part (10) according to claim 11, wherein the part (10) comprises a fiber-reinforced plastics material, e.g. SMC, BMC, or AMC, optionally coated in IMC.

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