WO2013139810A1

WO2013139810A1 - Device and method for spray coating an object with a hot-melt adhesive

Info

Publication number: WO2013139810A1
Application number: PCT/EP2013/055731
Authority: WO
Inventors: Yu Han; Fabian Kempe; Wilhelm Istemaas; Thomas Walther
Original assignee: Fmp Technology Gmbh Fluid Measurements & Projects; Baumer Hhs Gmbh
Priority date: 2012-03-20
Filing date: 2013-03-19
Publication date: 2013-09-26
Also published as: EP2827999B1; EP2827999A1; DE102012204426A1

Abstract

The invention relates to a device for spray coating an object (13) with a hot-melt adhesive (S), comprising a first nozzle (10) and a second nozzle (11), said first (10) and second nozzle (11) being arranged such that a first melt jet (St1) exiting the first nozzle (10) and a second melt jet (St2) exiting the second nozzle (11) meet each other at an acute angle (α) in such a manner that a spray fan (SF) is formed. A temperature maintaining device (8, 12, 14) is provided for maintaining the first and second nozzle (10, 11) at a specified target temperature ranging from 120 °C to 250 °C.

Description

Apparatus and method for spray coating an article with a hot melt adhesive

The invention relates to an apparatus and a method for spray coating an article with a hot melt adhesive.

From US 5,020,723 a device for spray coating an article with a hot melt adhesive is known. The device comprises a nozzle through which a melt jet is ejected under pressure. The nozzle is surrounded by an annular nozzle in the region of its nozzle opening, through which compressed air is ejected. The effect of the compressed air creates a ring or spiral spray. - For many applications, a ring or spiral spray is unsuitable. By the action of compressed air, although the finest hot melt adhesive droplets are formed. Investigations have shown, however, that the droplets thus produced have on their surface a solid skin, whereby the strength of an adhesive bond produced therewith is reduced. Abgese ^¬ hen which has the spray no particularly precise geomet ^¬ generic form. Ie. a portion of the spray, the ^so-¬ called "overspray" does not reach to be coated portion of the article, but undesirably into the environment. As a result, the environment becomes polluted. Apart from that, hot glue is lost.

The object of the invention is to eliminate the disadvantages of the prior art. It should in particular a forward direction and a method are provided which allow precise application of a hot melt adhesive to an object having ^¬ means of spraying. According to another object of the invention The intention is to improve the strength of an adhesive bond.

This object is solved by the features of claims 1 and 10. Advantageous embodiments of the invention will become apparent from the features of claims 2 to 9 and 11 to 17.

According to the invention, a device for spray-coating an article with a hot-melt adhesive is proposed with a first nozzle and a second nozzle, wherein the first and second nozzles are arranged such that a first melt jet emerging from the first nozzle and one out of the first nozzle second nozzle emerging second melt jet at an acute angle meet in a meeting point, so that forms a spray fan downstream of the meeting point, and wherein a temperature holding device for holding the first and the second nozzle at a predetermined target temperature in the range of 80 ° C to 250 ° C. is provided. With the proposed device it is now possible, in contrast to the prior art to apply a hot melt adhesive are arranged in the form of a flat spray fan at a point downstream of the fail ^¬ object. This creates new freedom when applying a hot melt adhesive by means of spray coating. It is possible, for example, to apply the hot-melt adhesive in a linear manner. Furthermore, relatively well-defined coating areas can be produced on the article. The Sprühfächer is inventively by a meeting of two ejected under pressure from the nozzles

Melt jets produced. In contrast to the prior art, no compressed air or compressed gas is used to produce the spray fan. An adhesive joint produced using the pre-chosen ^¬ device comprises egg ne improved strength. - Apart from that can be minimized with the invention of the "overspray". The proposed ^¬ ne device thus enables a particularly efficient spray coating of an article with a hot melt adhesive.

According to an advantageous embodiment of the invention, the acute angle is 10 ° to 80 °, preferably 20 ° to 60 °. The first and second melt jet are still advantageous way ^¬ enough, with respect to a meeting point of the two-melting, zestrahlen arranged symmetrically, ie the first and the second melt jet have up to the meeting point in Wesentli ^¬ chen the same length. They meet as a result, with et ^¬ wa same temperature each other, resulting in a particularly homogeneous spray pattern is formed.

According to an advantageous embodiment, the temperature maintaining means comprises a nozzle surrounding the thermal Iso ^{¬-regulation.} It has been found that even a thermal insulation of the nozzles can be sufficient for holding the nozzles at the predetermined setpoint temperature. For thermal insulation conventional temperature-resistant Isoliermateria ^¬ lien can be used, whose thermal diffusivity is less than the thermal conductivity of a material used for producing the first and / or second nozzle. The insulating material may be, for example, mineral wool, ceramic fiber mats or the like. act.

The temperature retaining device may further comprise a heating device, e.g. As heating bands or the like., Which surround the nozzles at least in sections. Thus, the nozzles are maintained at a temperature necessary for applying the hot melt adhesive. According to a further embodiment, the first and the second nozzle are each connected at their upstream end with a valve. The valve makes it possible, for example, to generate the spray fan intermittently. Thus, a variety of objects can be successively coated with hot melt at high speed.

According to a particularly advantageous embodiment of the invention, a further heating device for heating the valve is provided tils. The valve provided on the further Heizvor ^¬ direction can z. B. for heating, preferably provided with a thermal insulation, nozzles are used. In this case, the heater for heating the nozzles may also be omitted. This simplifies the structure of the device.

Furthermore, the temperature-retaining device may comprise a control device connected to the heating devices and / or the further heating device for holding the nozzles at the desired temperature. Thus, the device can be kept ready for use at any time. If the spray coating is interrupted, the hot glue will not freeze in the nozzle channels. By means of the proposed regulation, moreover, overheating of the nozzles is avoided.

Upstream of the nozzle having a melt ^¬ device is provided for melting a solid terials Heißkleberausgangsma- advantageously. Further, upstream of the nozzles, a pressure generating device may be provided for generating a predetermined pressure on the melt. It may be a suitable for promoting thermoplastic melts conventional Act pump. The pressure generating device is expediently connected between the valve and the melting device. By means of the pressure generating device, a pressure of 2 to 10 bar, preferably 3 to 6 bar, is applied to the melt.

In accordance with another aspect of the invention, a method is provided for spray coating an article with a hot melt adhesive, comprising the steps of:

Melting a hot melt starting material,

Ejecting the molten hot-melt adhesive through a first nozzle and a second nozzle such that a first melt jet emerging from the first nozzle and a second melt jet emerging from the second nozzle meet at an acute angle at a meeting point such that downstream of the meeting point Sprühfächer forms, the nozzles are maintained at a predetermined set temperature in the range of 80 ° C to 250 ° C. For the purposes of the present invention, at the "hot-melt adhesive starting material" is a set physically ^¬ the adhesive. Such an adhesive is usually at room temperature in solid, one-component form. It usually contains no or only small proportions of solvent. Preferably, the hot melt starting material is a thermoplastic, for example polyamide, saturated polyester or ethylene-vinyl acetate copolymers. The hot glue versions ^¬ starting material may contain additives such as tackifying resins, Plasticizers, stabilizers, antioxidants, fillers, extenders or waxes included. Furthermore, the term "hot melt starting material" also includes reactive

Melt adhesives understood that bind physically and chemically. These are Einkomponentensys ^{¬ systems} in which the hot melt z. B. cures under the action of UV light, moisture or water vapor, which is present in the article to be coated or in the environment. As a reactive hot melt adhesive, for example, polyurethane (PUR) hot melt adhesive can be used, which cures chemically under the action of moisture.

Because of the advantageous design features of the method, reference is made to the features described for the device, which can equally form embodiments of the method.

Embodiments of the invention will be explained in more detail with reference to the drawings. Show it:

Fig. 1 is a schematic representation of an inventive device ^¬ SEN,

Fig. 2 shows an embodiment of the device according to FIGS. 1 and

Fig. 3, the melt jets and the Sprühfächer according to

Fig. 1 or 2.

In the apparatus for airless spraying shown in Fig. 1, a container 1 is provided with a feeding device 2 for supplying hot melt starting material. The hot glue starting material may ^¬ example be present as granules. Reference numeral 3 denotes a ne first heater for heating the container 1 is called. The container 1 contains a melt S formed from the hot-melt starting material. The melt S can be formed, for example, from a thermoplastic polymer. A leading away from the container 1 first line 4 is connected to a, preferably heatable, pump 5. It may be, for example, a gear, diaphragm or piston pump. By means of the pump 5, the melt S is brought to a pressure in the range of 2 to 10 bar in a second line 6 provided downstream of the pump 5. The first 4 and the second line 6 are expediently heated. Reference numeral 7 denotes a valve which is provided with a second heating device 8. From the valve 7 branch off two third lines 9, which open into a first nozzle 10 and a second nozzle 11. The first 10 and second nozzles 11 are each provided with a third heater 12. Although not shown in the figures, it may also be that the first 10 and second nozzles 11 are each provided with a valve. In this case, the first 10 and the second nozzle 11 may each form a structural unit with the respective valve. The Bauein ^{¬ unit} may in this case also include the second 8 and / or third heater and / or thermal insulation. The first 10 and the second nozzles 11 are arranged so that ejected melt jets Stl, St2 meet at an angle of about 60 °. The nozzles 10, 11 expediently have straight cylindrical nozzle channels whose axes intersect or almost intersect. A meeting point of the melt jets Stl, St2 is designated by the reference symbol T. By the meeting of the melt jets Stl, St2 forms downstream of the meeting point T a Spray fan SF, which impinges on an object to be coated 13.

Fig. 2 shows a further embodiment of the invention. As far as the components used therein correspond to the components mentioned in Fig. 1, like reference numerals have been chosen. In a departure from FIG. 1, here the first 10 and the second nozzle 11 are not provided with third heating devices 12. The reference numeral 14 designates a thermal insulation, which substantially surrounds both the valve 7 and the first 10 and the second nozzle 11. In this case, the second heater 8 for heating the valve 7 is also used for heating the first 10 and second nozzles 11. The thermal insulation 14 can also advantageously be used to keep the third Lei ^¬ lines 9 at a predetermined temperature.

The function of the devices will now be explained in more detail with additional reference to FIG.

By means of the first heating device 3, hot adhesive starting material supplied to the container 1 is melted. The Tempe ^¬ temperature of the melt S is 120 ° to 250 ° C depending on the hot-melt adhesive starting materials ^¬ rial. Conveniently, the temperature of the melt S is kept constant by means of a (not shown here) control. By means of the downstream downstream pump 5, the supplied melt S is brought to a pressure of, for example, 3 to 6 bar. With the valve 7, it is possible to interrupt a connection to the third lines 9. The valve 7 is also maintained at a suitable temperature in the range of 120 to 250 ° C by means of the second heater 8. With the second heating device 8, a temperature can be set, which expediently 10 ° C to 20 ° C higher than the tempera ^¬ temperature of the melt S in the container. 1

The melt S passes downstream of the valve 7, preferably heated, third lines 9 to the first 10 and the second nozzle 11. From the first nozzle 10 exits under the pressure generated by the pump 5, a first melt jet Stl; from the second nozzle 11, a second melt jet St2 exits under pressure. The melt jets St1, St2 have expediently at the outlet opening of the nozzles

10, 11 - depending on the application - a diameter in Be ^¬ rich from 0.5 to 3.0 mm. The sharply defined melt jets St1, St2 meet at the meeting point T at the angle to each other. The angle is chosen so that a spray fan SF is formed. The Sprühfächer SF hits with a predetermined Auftreffbreite B on the downstream of the Treff ^¬ point T arranged object 13. A distance between the meeting point T and a surface of the object to be coated is z. B. 1 cm to 20 cm.

The spray fan SF generated with the device according to the invention is "flat", d. H. a thickness extending perpendicular to the impact width B is advantageously 1 to 10 times, preferably 2 to 6 times the diameter of the melt jets St1, St2 at the exit of the nozzles 10,

11. The thickness of the Sprühfächers SF ver ^¬ not shown here runs perpendicular to the paper plane.

The reference character Z denotes a plane of symmetry. In the embodiment shown in Fig. 3, the nozzles 10, 11 are arranged symmetrically to each other. A first length LI of the first melt stream Stl and a second length L2 of the second melt melt stream St2 are the same. In this case, a symmetrical spray fan SF is formed.

In the context of the present invention, however, it may also be that the first 10 and the second nozzle 11 are not arranged symmetrically to each other. Further, it may be that the first length LI is different from the second length L2. This makes it possible to produce asymmetric Sprühfächer SF.

The method proposed or "airless spraying" is particularly suitable for applying a hot-melt adhesive to non-woven or woven items 13. With the pre-chosen process ^¬ hot melt adhesive compounds can be achieved excellently gender strength. Further, it is possible with the beaten before ^¬ device to apply hot glue defined line-shaped or in the form of rectangular coating surfaces on objects. 13 In the case of a rotation of the article 13 during the spray application surfaces, circular or circular-sector-shaped supporting surfaces on ^¬ can be generated.

Reference sign list

1 container

2 feeder

3 first heating device

4 first line

5 pump

6 second line

7 valve

8 second heater

9 third line

10 first nozzle

11 second nozzle

12 third heater

13 subject

14 thermal insulation

S melt

SF spray fans

Stl first melt jet

St2 second melt jet

T meeting point

angle

Claims

claims

A device for spray-coating an article (13) with a hot-melt adhesive (S), with a first nozzle (10) and a second nozzle (11), wherein the first (10) and the second nozzle (11) are arranged such that a from the first nozzle (10) exiting the first melt stream (Stl) and one from the second nozzle (11) from ^¬ kicking second melt jet (Stl) meet at an acute angle (), so that a spray fan (SF) is formed, and wherein a temperature hold means (8, 12, 14) for holding the first (10) and the second nozzle (11) on a specified ^differently surrounded target temperature in the range of 120 ° C to 250 ° C is provided.

2. Device according to claim 1, wherein the acute angle () is 10 to 80 °, preferably 20 to 60 °.

3. Device according to one of the preceding claims, wherein the temperature-retaining device comprises a nozzle (10, 11) surrounding the thermal insulation (14).

4. Device according to one of the preceding claims, wherein the temperature-retaining device comprises a heating device (12) surrounding the nozzles (10, 11) at least in sections.

5. Device according to one of the preceding claims, wherein the first (10) and the second nozzle (11) are each connected at its upstream end with a valve (7).

6. Device according to one of the preceding claims, wherein a further heating device (8) for heating the valve (7) is provided.

7. Device according to one of the preceding claims, wherein the temperature-retaining device comprises a control device connected to the heating devices (12) and / or the further heating device (8) for holding the nozzles (10, 11) at the desired temperature.

An apparatus according to any one of the preceding claims, wherein upstream of the nozzles (10, 11) is provided a melting device (3) for melting a solid hot-melt starting material.

9. Device according to one of the preceding claims, wherein upstream of the nozzles (10, 11) a Druckzeugungsvor ^¬ direction (5) for generating a predetermined pressure on the melt (S) is provided.

10. A method of spray coating an article with a hot melt adhesive, comprising the steps of:

Melting a hot melt starting material, ejecting the molten heating adhesive (S) through a first nozzle (10) and a second nozzle (11), so that from the first nozzle (10) exiting the first melt stream (Stl) and one from the second nozzle (11) from ^¬ kicking second melt stream (ST2) (at an acute angle) meet each other such that a spray fan (SF) forms wherein the nozzles (10, 11) are maintained at a predetermined desired temperature ^¬ ture in the range of 120 ° C to 250 ° C.

A method according to claim 10, wherein the acute angle (θ) is 10 to 80 °, preferably 20 to 60 °.

The method of claim 10 or 11, wherein the nozzle channels are maintained at the desired temperature using thermal insulation (14).

13. The method according to any one of claims 10 to 12, wherein the nozzles (10, 11) by means of a heater (12) are maintained at the desired temperature.

14. The method according to any one of claims 10 to 14, wherein for heating the nozzles (10, 11), a further heating device (8) is used, which is part of an upstream of the nozzles (10, 11) provided valve (7).

15. The method according to any one of claims 10 to 13, wherein the nozzles (10, 11) are held using a control at the target temperature.

16. The method according to any one of claims 10 to 15, wherein the solid hot melt starting material is melted by means of a melting device (3) provided upstream of the nozzles (10, 11).

17. The method according to any one of claims 10 to 16, wherein on the melt (S) a predetermined pressure by means of an upstream of the nozzles (10, 11) provided for pressure generating device (5) is applied.