KR20160007551A - Spray-coating method - Google Patents

Abstract

The present invention relates to a spray coating method of a substrate surface, by which a variety of thermoplastic processable materials can be applied to a wide variety of types of surfaces.

Description

Spray coating method {SPRAY-COATING METHOD}

The present invention relates to a method of spray coating a substrate surface on which a variety of thermoplastic processable materials can be applied to a wide variety of surfaces by spray techniques.

[0003] A wide variety of types of methods are known for the provision of thin sheet-like components or insulation on, for example, fabrics. Depending on the application, these methods are different in shape quality, material, thickness distribution, and technology itself on the substrate (component).

Known methods include deep-drawing, vacuum-deep-drawing, pressing, and the like, for sheet processing for forming parts or individual layers.

In the production of sheet-shaped components by these methods, the local mass distribution is determined by deformation of the sheet and can not be set in a defined manner. For this reason, for example, the insulation thus produced becomes thicker than necessary in view of the sound absorption function. This prevents lightweight construction, especially in automobiles.

For material sealing, the sheets are attached to a wide variety of types of substrates by adhesive or hot-melt bonding.

For partial soundproofing, from the viewpoint of sound absorption, a so-called heavy layer sheet is placed in the carpet or partition zone, and is adhered by adhesive or hot-melt bonding.

As an alternative, it is known to manufacture automotive thin sheet shaped components, such as heavy layer components, for soundproof components comprising a partition made by injection molding of thermoplastic and thermoset materials.

Injection molding (thermoplastic injection molding or reaction injection molding (RIM)) enables the manufacture of components having masses that are defined differently per unit area. Due to the high investment in the plant and mold, it has to be mass produced by this method.

In the RIM process, there is an additional problem that the material employed, for example polyurethane, is expensive and can not be recycled. In particular, in the insulation component of a vehicle, the mass distribution for all superstructures is determined by the geometry of the mold. This also can hinder the sound absorption optimization of the intended series of individual vehicle types (engine version) in terms of sound absorption.

Also known are methods of making such sheet-like components by sintering of the powders. The powder is applied to a heated mold where a plastic layer is formed by sintering followed by cooling and component recovery. This technology is time, tool and energy intensive. Thus, this method is limited to the manufacture of high-quality components such as slush-molded skins.

Methods for coating and manufacturing sheet-like components by spraying are known. The spraying of the thermoplastic material consists of a melt by one or more nozzles, or a "cold" plastic powder by direct thermal environment during the scattering step or by heating on the flame in the carrier gas or during the scattering step. However, these methods are only conditionally suitable for what is very low throughput and coating of the substrate, i.e., heat resistance. In the coating of the fabric, the high temperature destroys the fabric material before application is complete.

The spray method is applicable to the regeneration of powders. DE 10 2005 050 890 A1 describes a process and an apparatus for producing nanocomposites in which the separating agent and the dispersant, if any, are present in the polymer melt by high-pressure spraying. In this way, polymer droplets rapidly solidify as a result of rapid cooling resulting from relaxation from high pressure levels to ambient pressure. This results in nanocomposites.

As a heavy layer for spraying, a bridged PUR system is employed. The details are described in DE 101 61 600 A1 and DE 10 2005 058 292 A1. These materials are very expensive and can not be reused.

Also known are methods and apparatuses in which plastic beads are placed on the surface of a substrate to be predominantly pretreated. EP 0 524 092 B2 describes a method and apparatus for making products with profiled cords. The profiled cord is produced by an extrusion die which is connected to the extruder through a heated flexible pressure tube and which is placed underneath.

DE 30 47 727 C2 describes a method for producing a thin protective film by spraying a liquefied thermoplastic material onto a substrate. It is contemplated that the method described herein is capable of using a conventional hot spraying apparatus wherein the injection material is melted and liquefied and can be applied directly to the surface to be protected. In addition, although the tendency of these materials to form beads at the time of surface collisions has prevented the formation of sufficiently uniform films to date, according to the description, this problem is overcome in a simple manner by a simultaneous or subsequent sintering process ≪ / RTI > Thus, it has been found that for sintering of thermoplastic materials there is an advantage when sintering is performed by heating the thermoplastic material to be sprayed to achieve uniform, smooth and pore-free application. Heat required for sintering may be supplied to the thermoplastic material from the outside by radiation heat, supply of heated air, or the like. It may be desirable to spray a thermoplastic material onto a preheated surface so that the sintering process and the spraying occur simultaneously, thereby resulting in a time optimization process of the process. However, the sintering process that takes place after the material collision to the surface is very complex and again places the substrate material under heat load.

DT 16 46 051 B2 describes a method for applying a polymer coating to a solid surface by spraying a molten thermoplastic polymer. Thereafter, the polymer is melted and the melt is supplied to the pressurized gas stream by emptying, and the sprayed gas / polymer jet is subjected to a heated jet treatment on the surface to be coated. A thermoplastic polymer of any particle size is converted to a molten state in the extruder or piston cylinder means and the surface to be coated previously heated by a compressed gas using an air injection nozzle compressed in the form of a gas / polymer jet heated by a thermal jet stream Is sprayed onto the surface of the substrate.

DE 32 25 844 A1 describes a method and apparatus for applying layers of a thermoplastic material or a hot-melt adhesive. As a method for applying thermoplastic materials or layers of hot-melt adhesives, it is described to melt and then spray spray the employed plastic or hot-melt adhesive. Preferably, the temperature of the molten plastic or hot-melt adhesive remains constant until the moment of spraying. The apparatus for carrying out the method may comprise a melting means capable of heating for a plastic or hot-melt adhesive, a heatable spraying means having a nozzle, a heatable device for feeding the molten material into the spraying apparatus, A loop control system, and a closed loop control system for feeding and dispensing molten material and heated spraying gas, if any. By this method, any kind and type of two-dimensional or three-dimensional object can be provided with a layer of any thickness, uniformity or pattern inside and / or outside.

DE 42 31 074 A1 describes the use of plastic powders as fillers in sprayable coating compositions, paints and sealing compositions. A sealant composition of one or two component polyurethane binder system, sprayable paint and coating, optionally with additional filler, as well as a mineral filler which may contain mineral filler as a filler, The use of powders in the density range of 0.1 g / cm < 3 > to 2.0 g / cm < 3 > with an average particle size is described.

DE 101 61 600 A1 describes a method of spraying onto a plastic layer. A method and apparatus are disclosed for applying a plastic layer containing a filler to a surface to be formed wherein a mixture containing a mixture of a binder, a solid conveyor and a filler is first sprayed with a mixture comprising a mixture of a binder and a solid conveyor The filler is sprayed onto the surface formed by creating a prejet for application and then metering the filler to the prejet for the incompletely polymerized mixture of the binder. This method is particularly suitable for spray application of heavy layers employed in conventional mass-spring systems.

DE 10 2005 058 292 A1 describes a method and apparatus for producing a coated formed part. A shot operation in which reactive components are mixed by a cylindrical mixing chamber and a subsequent reaction mixture flows through a flow path to be sprayed onto the surface of a substrate and the flow path is cleaned by a gas stream following curing, There is provided a method and apparatus for making a part to be formed that includes a layer.

Accordingly, it is an object of the present invention to provide a process that can apply a wide variety of thermoplastic processable materials in a desired and desired manner to a variety of substrate surfaces in film form.

According to the present invention, this object is achieved by the spray coating method of the following substrate surface.

(a) melting and liquefying a thermoplastic material in an extruder as a first step;

(b) pressurizing the molten material with a carrier gas or vapor;

(c) pressurizing the molten material and the mixture formed by the carrier gas or vapor through one or more nozzles and, optionally, applying a spraying jet to the spraying jet in the region of the discharge opening of the nozzle, Supplying a spraying gas having a high temperature; And

(d) directing the resulting spray jet with the molten material to a surface of the substrate, the material colliding with a droplet of flowable material on the surface of the substrate to form a continuous coating on the surface of the substrate, being.

The essence of the present invention is essentially that the thermoplastic processable material in the extruder is melted alone or as a compound of a mixture with other thermoplastic processable materials with or without a filler and the inorganic carrier gas Or pressurized with steam, pressurized as a mixture through one or more orifice nozzles, discharged at atmospheric pressure, and cooled only on the substrate surface.

In certain embodiments, the compounds are directly mixed in a twin screw extruder. In another embodiment, this biaxial screw extruder is followed, for example, by a single screw extruder or a melt pump.

Substantially all of the thermoplastic processable material may be employed as the material for spraying regardless of whether the non-fusing material is unfilled or filled homopolymer or compound. Within the meaning of the present invention, the thermoplastic processable material is a homopolymer, a copolymer and a terpolymer, as well as a thermoplastic processable elastomer and the like, and in particular an ABS resin comprising a copolymer and a compound which may optionally contain further components, such as acrylonitrile-butadiene-styrene, polyamide, polylactate, polymethyl methacrylate, polycarbonate, polyethylene terephthalate, polyethylene, polypropylene, polystyrene, Polyether ether ketone (PEEK) and polyvinyl chloride (PVC). In certain embodiments, high performance materials, such as PEEK, may also be sprayed with a high proportion of gas and reduced relative viscosity. The amount of filler can vary widely, wherein the amount of filler should preferably not exceed 80% by weight, depending on the material, because otherwise the coagulation of the coating can not be ensured.

The filler itself may be a polymer whose properties are inorganic or that are not melted at a processing temperature such as rubber, where the filler does not have the desired orientation. In addition, short fibers, polymer fibers, as well as natural fibers having a melting temperature higher than the treatment temperature of the material or compound can be employed as fillers.

By varying the ratio of the thermoplastic processable material to the filler in the course of the spraying process and by changing the mixture, the thermoplastic processable material and / or the filler itself, different material structures in the layers can be made.

The vapor itself, as well as an inert, especially a mixture of inorganic gases or gases, is presented as a carrier gas. In particular, according to the present invention, it is preferable to use, for example, nitrogen, carbon dioxide, air or water which is a gas at this temperature.

The carrier gas or the vapor is preferably employed in a weight ratio of 100: 0.1 to 100: 30 parts by weight, particularly 100: 0.3 to 100: 15 parts by weight, of the thermoplastic processable material to the carrier gas or vapor Do. It is preferred that spraying jets having a pressure of 10 bar to 500 bar, especially 20 bar to 400 bar, are sprayed.

With increasing pressure, the droplet size is reduced, thereby making the application of the material more uniform. However, with increasing pressure, the material is cooled more rapidly at the time of expansion and relaxation. Depending on the material, this results in no further bonding with the substrate surface. In this case, the heated gas (spray gas) to be pressurized, preferably air, should be supplied and prepared for further spraying if it is smooth.

The nozzle is provided, for example, in a flexible pressure tube and is moved by the robot over the surface of the substrate to enable full application of the material. The nozzle (s) themselves may be, for example, 1 to 50 orifices, preferably 5 to 20 orifices, with a diameter of 0.1 mm to 10 mm, preferably 0.5 mm to 2 mm, (S) having an orifice having an equivalent cross-sectional area to a defined orifice geometry of the diameter. Hot air (spray gas) can be introduced for additional heating.

In addition, a slot-type nozzle having a dimension of 0.1 mm to 3.0 mm x 3 mm to 30 mm, preferably 0.5 mm to 2.0 mm x 5 mm to 10 mm may be employed, Can be provided on the head.

The term "carrier gas" in the sense of the present invention, in addition to the above-mentioned materials and elements which are gaseous at room temperature (normal pressure) or at a treatment temperature, refers to a substance which forms a gaseous substance by chemical or thermal reaction, Also included. In this respect, hot air is particularly preferable.

Preferably, the chemical composition of the spray gas guided around the discharge opening of the thermoplast in the form of an annular nozzle may be the same as, or different from, the carrier gas. Especially hot air is preferred as the spray gas, which causes additional expansion of the carrier gas and heating of the particle surface in the thermoplast.

In the following, the present invention is illustrated by two embodiments.

Examples

Example  One :

Commercially available Krauss Maffei Berstorff extruders ZE40 Ax29D and KE90x30D were used in the series, each with specially designed screws. The die was a single casing head with 24 orifice nozzles arranged in two rows and with an orifice diameter of 1.1 mm each.

A commercially available 25 wt% plastic mixture of a 75 wt% inorganic filler (barite), a granular temperature stabilizer, a PE / EVA, a white oil, and a flow additive was used as the thermoplastic processable material.

The output capacity was 90 kg / h, and the amount of gas (carrier gas) was 1.1 kg / h CO ₂ . A commercially available pressurized mixed fiber nonwoven fabric was used as the substrate surface.

With this setting, good spray performance was achieved and a flexible plastic layer was created on the fabric surface.

Example  2 :

In principle, essentially the same settings as in Example 1 were used for the second application of this example. The nozzle has been changed. Here, a round jet nozzle from BETE was used, where hot air as a spray gas in the outer ring around the discharge nozzle heated the carrier gas and the mixture of compounds. The amount of the carrier gas was reduced to 400 g / h. For the material employed, the filler was reduced to 25 wt.% And thus the amount of compound increased.

The output capacity was 60 kg / h. The amount of air (spray gas) employed was 30 standard cubic meters per hour heated to 300 ° C. The spraying results were improved over that of Example 1.

Claims (17)

(a) melting and liquefying a thermoplastic material in an extruder as a first step;
(b) pressurizing the molten material with a carrier gas or vapor;
(c) pressurizing the molten material and the mixture formed by the carrier gas or vapor through one or more nozzles and, optionally, applying a spraying jet to the spraying jet in the region of the discharge opening of the nozzle, Supplying a spraying gas having a high temperature; And
(d) directing the resulting spraying jet with the molten thermoplastic processable material to a substrate surface, wherein the material impinges on the surface of the substrate in a flowable state to form a continuous coating , And then orienting the material to be solidified
Spray coating on substrate surface. The method according to claim 1,
The thermoplastic material is selected from a homopolymer or a copolymer and a terpolymer or a thermoplastic processable elastomer and in particular a copolymer which may optionally contain further components, (Acrylonitrile-butadiene-styrene), PA (polyamide), PLA (polylactate), PMMA (polymethyl methacrylate), PC (polycarbonate), PET (polyethylene terephthalate), PE (polyethylene) , PS (polystyrene), PEEK (polyether ether ketone) and PVC (polyvinyl chloride). 3. The method according to claim 1 or 2,
Characterized in that an amount of filler from 0% to 80% by weight is employed, depending on the thermoplastic processable material. The method of claim 3,
Characterized in that the filler is inorganic in nature. The method according to claim 3 or 4,
Wherein the filler is in the form of an inorganic short fiber. 6. The method according to any one of claims 3 to 5,
Wherein the filler has polymer fibers having a melting temperature higher than the treatment temperature of the compound. 7. The method according to any one of claims 3 to 6,
Characterized in that the filler comprises natural fibers. 8. The method according to any one of claims 1 to 7,
Wherein the weight ratio of the thermoplastic processable material to the filler as well as the mixture, the thermoplastic processable material and / or the filler itself varies in the course of the spraying process. 9. The method according to any one of claims 1 to 8,
Characterized in that nitrogen, carbon dioxide or air is employed as the carrier gas and / or the spraying gas. 10. The method according to any one of claims 1 to 9,
Characterized in that a spraying jet having a weight ratio of the thermoplastic processable material to the carrier gas of 100: 0.1 to 100: 30, in particular 100: 0.3 to 100: 15 is employed. Coating method. 11. The method according to any one of claims 1 to 10,
Characterized in that a spraying jet having a pressure of from 10 bar to 500 bar, in particular from 20 bar to 400 bar, is employed. 12. The method according to any one of claims 1 to 11,
Characterized in that 1 to 50 nozzles, in particular 5 to 20 nozzles, with different output cross-sections are employed. 13. The method according to any one of claims 1 to 12,
Wherein the mixture is forced through an orifice and / or a slotted nozzle. 14. The method according to any one of claims 1 to 13,
Characterized in that an orifice nozzle having the same or different diameters in the range of 0.1 mm to 10 mm, preferably 0.5 mm to 2 mm, or a discharge opening having a cross sectional area corresponding thereto is employed. 15. The method according to any one of claims 1 to 14,
Characterized in that a slot-like nozzle having the same or a different cross-sectional area of 0.1 mm to 3 mm x 3 mm to 30 mm, in particular 0.5 mm to 2 mm x 5 mm to 10 mm is employed. 16. The method according to any one of claims 1 to 15,
Characterized in that a continuous coating is provided which itself is porous or coherent. 17. The method according to any one of claims 1 to 16,
Characterized in that a substrate selected from mold cavities or fabrics with or without a surface structure is employed.