JPS6362574A - Fluid spray application method - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for applying adhesives and surface coatings, particularly reactive adhesives and reactive surface coatings, by electrostatic spraying, and to a production line using the coating method.

In electrostatic spraying of known non-reactive materials, a fluid introduced into a relatively strong electric field through an electrically charged spray nozzle creates charged filaments or sluices that move towards the ground, and which are exposed to the electric field. It is collected on a suitable substrate which may be an electrode or something other than a field electrode.

British Patent No. 1,569,707 describes a "field intensifying electrode" which is grounded adjacent to the spray head.
ctrodes); this can advantageously reduce the required operating potential and reduce current losses due to corona discharge from the spray head. Spraying using this type of equipment is described below as “
"electrodynamics spray"
"praying").

As disclosed in GB 1,569,707, a typical "adjacent" electrode using a typical 20 kV spray head operating voltage is about 2.
0 mm and thus this electrode is very different from the usual auxiliary electrodes used in electrostatic spraying.

For example, in the industrial application of adhesives and surface coatings in packaging materials, component assemblies (e.g. shoes, aircraft and boat frames), or surgical dressing and lifting production lines, accuracy and economy of application are generally important. Because of the requirements, a contact application method is required.

Furthermore, known manufacturing lines require relatively high productivity for economical operation and fast-set/cure adhesives or coatings. ing. Contact application generally does not provide the desired speeds.

Reactive adhesives or coatings are often multicomponent systems;
These components are therefore not conveniently mixed by contact coating methods, or special and expensive curing methods are required. Rapidly reactive room temperature multi-component system
ctingroom termperature mu
lti-component 5ystea+) cannot be applied by contact because the reaction is too fast. Hot melt (quick drying) adhesives have been used as a solution to this problem in packaging adhesives, but this method requires unnecessary heat treatment.

Surprisingly, the inventors have discovered a method for spray application of adhesives and surface coatings that combines the accuracy of contact application methods with the rapidity of spray application methods. This method is particularly useful for rapidly reacting, room temperature, multi-component systems in which proper mixing of the components and favorable application can be achieved.

Thus, in accordance with the present invention, there is provided a method for electrodynamic spraying of fluids, preferably reactive fluids, which are adhesives or surface coatings or their precursors. Namely, one aspect of the present invention is to supply the fluid to a spray head and place the fluid in a strong electric field.

The fluid is thereby moved out of the spray head under the influence of the electric field to form a spray, and is characterized in that the electric field is intensified by means of charged electrodes arranged adjacent to the spray head.

The fluid may be an adhesive or a surface coating or a precursor thereof, or a solution, dispersion or! It may be a suspension or, less preferably, a melt.

The fluid may also be a single fluid or a reactive precursor thereof, or it may be one of the multicomponent precursor components of a multicomponent adhesive or surface coating in which all components are sprayable.

In the case of a single fluid precursor, the precursor typically undergoes external activation after being ejected from the spray head before reacting on its own to form an adhesive layer or surface coating. The multicomponent precursors react with each other or continue to react after being ejected from the spray head.

Preferred fluids are described in more detail below.

When atomizing a single fluid according to the invention, only one spray head is required. Multiple fluids (e.g. 2
In the case of spraying (species), this spray is applied to a) separate substrate surfaces, for example, where the two fluids come into contact with each other in flight or at the substrate surface, or in the case of adhesives, on separate substrate surfaces which are later brought into contact with each other. or b) using a single spray head with multiple feed ports for a single outlet or multiple outlets, A method of adhering before, during, or during flight.

This can be done either by:

In use, of course, the single spray head or each spray head is charged to a different potential than the substrate potential and the field enhancing electrode; the substrate potential is usually at ground potential.

An electric field is thus formed between the spray head and the grounded substrate and the field-enhancing electrode, and the fluid atomized from the spray head picks up a charge on the spray head, either at a lower earth potential of the same sign or of the opposite sign. It is attracted toward adjacent surfaces that are at electrical potential. An electric field enhancing electrode, typically located adjacent to the spray head, does not affect the electric field enough to target it. The substrate is usually
``Trajectory'' of the spray (``1ine offfire'')
the closest grounded surface, and most (if not all) of the spray is attracted and impinges on the substrate; in fact, the spray parameters are The object can be controlled to impact only a portion of the substrate as desired. Indeed, even when using non-conductive or semi-conductive substrates (eg cellulosic plastics or siliceous substrates).

The use of regular target (field) electrodes behind these substrates may not necessarily be strictly necessary if tight control of the spray pattern is not desired (see "Auxiliary Electrodes" below). .

In one embodiment, the invention provides a device for spraying a fluid, in particular an adhesive or a surface coating or a precursor thereof, comprising a spray head having a channel for the fluid communicating with an outlet and a device for spraying the fluid in a strong electric field. a device for displacing the fluid from the spray head and forming a spray under the action of an electric field; the latter device applying a first electrical potential to the fluid;
An electrode provided adjacent to the spray head and this W1
The device includes a device for applying a second potential to the battery.

A single fluid, which reacts on its own after being sprayed from a spray head, is typically sprayed from a single spray hole (outlet). However, (although not necessarily) multiple mutually reactive fluids may be mixed within a spray head (e.g., within a mixing chamber) to form a single fluid, which is then delivered to a single spray hole. You can also spray it from there.

When spraying onto a substrate having an earth potential, the first potential is ±1 to 20 kV and the second potential is equal to or less than the earth potential, as disclosed in British Patent No. 1,569,707. The potential is close to that.

British patent issued! As disclosed in the patent publication for which priority was claimed based on No. 1iNo. 8432274, the first potential is 25 to 50 kV, and the second potential is ±10 to 40 kV.
But, tl.

The electrode consists of a core of conductive or semiconductive material and a sheath material sheathing the core, the sheath material having a dielectric strength sufficient to prevent sparking between the electrode and the spray head. A material having a volume resistivity and a volume resistivity low enough to conduct charge collected on the surface of the seed material through the seed material to the conductive or conductive core. The volume resistivity of the seed material is 5X1011 ~
5×103ohllI-cm, the dielectric strength of the sheath material is greater than 15 kV/mm, and the thickness of the sheath material is 0.75-5 mm, preferably 1
．． It is 5-3+nm. A sheathed electrode of this type is also disclosed in the applicant's co-pending application which has been filed claiming priority from GB Pat. No. 8,432,274.

A sheathed electrode (sh
Eathed electrons are particularly used for spraying at high flow rates (e.g. spraying insecticides on the ground) as disclosed in the reference specification. However, in general, when applying adhesives to relatively small objects such as packaging materials, or when applying surface coatings, for example, practical or preferred production line speeds do not require such high flow rates. is required and therefore the use of this particular device is not believed to be required.

Preferably, the electrode is adjustable so that the relative position of the spray head and electrode can be easily changed.

The spray can be diffused by placing an electrode upstream of the effluent spray, and it can be focused by placing an electrode downstream of the effluent spray.

In the above device having one or more single spray heads, the one or each spray head may be of any type commonly used for atomization of fluids in the field of electrostatic spraying. . However.

At the end of the supply conduit, the spray head has a nozzle orifice (usually annular), an annular slot (for example formed by an annular core with concentric cores) or a rectangular slot. These slots may be convexly or concavely curved along their length. All these openings are preferably of near-capillary size 1, eg 0.05 to 0.5 square meters, to aid atomization. Similarly, the openings are preferably delimited by sharp edges (and may also be interlocking) to enhance the field strength at the spray head surface and thus its atomization.

Because of the proximity of the electrode to the spray head, it is often the case that the electrode has the shape of the fluid orifice, e.g. two parallel bars with slots, or a ring or torus with a circular or annular nozzle. Preferably, it conforms to the shape.

Atomization and/or effective deposition of the spray, in some cases,
This can be facilitated by introducing a gas stream with (or less commonly across) the exiting spray, as in JK 1569707. In some cases, this gas stream is heated.

For certain free-radical curable adhesives and surface coatings, there is an additional advantage in having them act as thermal initiators or dispersing catalysts or catalytic initiators and/or promoters.

In another aspect, the invention uses a device for spraying multiple fluids, particularly precursor components of multi-component adhesives or surface coatings. The device includes a spray head having a plurality of fluid flow paths communicating with a spray hole, and means for applying a strong electric field to the fluid at the spray hole and spraying the fluid from the spray head under the action of the electric field to form a spray. and
The spray holes are arranged so that the fluids mix on or in flight from the spray head.

The means in the apparatus include means for applying a first voltage to at least one of the fluids, an electrode disposed adjacent the spray head, and means for applying a second voltage to the electrode.

When multiple fluids are sprayed from a single spray head having multiple feed channels, these feed channels may be formed by closely adjacent orifices or slots (e.g. parallel rectangular slots) or closely spaced spray heads. Preferably, it ends in adjacent coaxial circular orifices and annular slots or likewise coaxial annular slots. Mixing of each component as an eruption product occurs at the point of flight or during flight.

For single spray heads, sharp toothed edges and forced gas flow are advantageous.

When the feed channels terminate in closely adjacent parallel slots, they are preferably in the form of grooves between parallel plates.

Good mixing of the two components is achieved if the spray head consists of four such plates, ie two inner plates and two outer plates defining three grooves. The plate is symmetrical about the central groove, the edges of the plate with the spray hole slots are grooved towards the central spray hole, and the central spray hole is located downstream of the two outer spray holes. A wide wedge-shaped (i.e., sharp-edged) spray hole edge of the spray head is suitable.

The included angle of the groove or slope on the inner plate is smaller than the included angle of the slope of the outer plate, 10° to 60° and 80° to 150°, respectively.
A range of 50° is preferred.

In use, one component flows down the central channel and the other components flow down the two outer channels.

A three plate and two groove spray head may also be used, with the central plate having two opposing slopes relative to the two inner plates as described above. This spray head is also generally sphenoidal.
It is.

The edges of the plates may be convexly or concavely curved along their length.

Similarly, for a binary system, the three feed passages terminate in closely adjacent circular orifices and coaxial annular slots;
e) and a groove delimited by these tubes and a coaxial outer tube interior. Again, good mixing is achieved when the outlet ends of the tubes are symmetrical about a common tube axis, grooved towards the central outlet, and the central outlet is downstream of the outer outlets; The spray head can be given a wide conical exit surface.

Suitable and preferred angles of inclusion of the beveled ends of the tubes are as described for similar plates above.

In use, one type of fluid component flows down from the central groove,
Other components flow down from the outer channels.

This type of spray head and field-enhancing electrode are available in the UK
No. 8,504,253, which is a pending application claiming priority.

Matters regarding the operating voltage and its nature, electrode shape and use are also as for the single spray head described above.

The arrangement of any of the above spray heads in use is generally not critical.

In all the above spray heads (single and plural), suitable means for applying an electric field to the fluid at the outlet or outlets include at least one (
(preferably both or all) in the spray head or outlet (e.g. the outlet surface of a conductive or semi-conductive spray head) or a short distance upstream thereof (e.g. an embedded electrode in a non-conductive spray head) eg, metal electrodes capable of being charged.

Any suitable method of producing the desired voltage can be used; for example, a transformer and rectifier mains supply or a Van der Graaf generator can be used.

The electric field enhancement electrode can be turned off, the inductive or resistive tap turned off and the transformed spray head 5upply, for example.

Conventional insulation precautions must of course be installed at all points other than earth voltage.

The atomized droplets of adhesives and surface coatings produced according to the invention under the action of an electrostatic field tend to produce a layer on the substrate that is very uniform, essentially free of pinholes, and without closing air pockets. . This results in the formation of a desirable uniform adhesive layer with good adhesion and no scratches to a maximum of the substrate surface area and, for example, a thick, pinhole-free barrier coating.
For example, it is useful in forming corrosion-resistant coatings.

The average particle size of the atomized droplets can generally be controlled by the position of the electric field enhancement electrode relative to the spray head surface. For example, for a fluid with a specific flow rate, f
Moving the fi pole closer to the spray head surface generally produces smaller sized droplets.

By controlling the position of the electrodes, droplets of a certain size can be produced to suit a particular application. For example, large numbers of small particles (eg, 20-30 micron diameter) are preferred for maximally thin coatings of substrates, while large particles are preferred for thick films.

The method of the present invention is versatile in that it can apply adhesive films as thin as about 1 micron as well as thick surface coatings (eg thick coats ff) as thick as 1 mm or more.

It becomes possible to use a rapid reaction system, making it easy to produce thick coatings without bending.

The method of the invention can be used to coat a wide range of substrates (including those treated by contact coating or conventional spraying methods) as long as it is compatible with the adhesive or surface coating used. It is particularly useful for continuous production on either strip or continuous substrates. Examples of substrates are monolithic and/or continuous; suitable substrates include:

As packaging, e.g. paper, board, wood and plastic films and sheets, as sheets (for processing into packaging, laminates, shoe soles, aircraft skins and boat hulls and such processed items), e.g. paper, board, plastic metal.

Textiles (pieces or webs), e.g. adhesive finishes, structural members (including shoe uppers, aircraft and board frames)
, for example, textile fibers such as plastic and metal fibers, silicon-based or plastic optical fibers, tensile fibers such as fibers for reinforced metal and reinforced plastic composites, and thermoplastic fibers.

Of course, the spray head and the substrate may be stationary relative to each other during spraying, or they may be moving relative to each other during spraying. Such movement may be continuous or discontinuous, and may occur during part or all of the spraying process.

Particularly when the substrate is a continuous object, the substrate is often moved relative to a stationary spray head, but it is also possible, for example, to move the spray head across a long continuous substrate on a programmable robot arm or gantry. is also useful.

Similarly, if the substrate is in the form of flakes, it is often preferable to move each flake into a spray position on the production line and then move the spray head to coat different parts of the flake. .

When applying a single fluid with a single spray head or several fluids with a spray head having multiple feed channels, such several fluids should be separated to avoid electrostatic interference with each other. Spray heads can be stored and used simultaneously on different parts of the same substrate or on different substrates.

When mixing two liquids in-flight or on a substrate using a single spray head, in-flight mixing requires simultaneous spraying of the components, while on-substrate mixing requires spraying of the components simultaneously. This can be done by spraying the same area at the same time, or by spraying the same area sequentially and mixing sequentially, or by moving a given area from one sprayer to another and spraying at the same time. In some cases, this can be carried out by separately spraying two substrate surfaces and then bringing them into contact.

However, the inventors have found that in-flight mixing generally allows for a more satisfactory mixing of the components, resulting in a more uniform cure and therefore better quality adhesion and surface coverage.

The device used may also have one or more auxiliary electrodes that apply sufficient atomizing voltage without being close enough to the spray head to further influence the spray pattern. be able to.

In a further aspect, the invention provides a method according to the invention, characterized in that the distribution of the electrostatic field is controlled and modified by said at least one auxiliary electrode.

The shape and position of the auxiliary electrode and the relative voltages all affect the spray pattern. A large number of patterns are possible with this method, and therefore these parameters may vary if they are the same parameters, in particular electric field voltage and spray distance (q, V,)
can vary within a wide range as it acts. And appropriate values can be easily determined by routine trials as well.

The simplest form of auxiliary electrode is one conventional conductive target (electric field) electrode, for example at ground voltage and behind the target substrate. Such electrodes tend to focus the spray into a pattern on the substrate, and this pattern tends to match the shape of the electrode.

Relatively complex deposition patterns can be achieved in this way.

On the other hand, any auxiliary electrode may have any suitable shape, such as a straight, curved or annular metal rod, or a similar rod that is flat, curved, dish-shaped, cylindrical, partially or completely in the form of an annular grid. . Such electrodes can be connected in a network at different locations, but can be held at the same or different voltages. Regarding the atomization parameters mentioned above, the length or ring diameter is 5 mm with a diameter of 1 to 10 mm.
A planar, curved or cylindrical lattice made of straight rods, a curved or dish-shaped lattice made of curved rods, using straight, curved or annular steel rods of 0 to 500 nl11, singly or in an array. , formed into a cylindrical or partially or entirely donut-shaped lattice of annular rods, in each case with a spacing of 10 to 100 mm between the rods.

Each auxiliary electrode may be at the same potential or at an intermediate potential between the spray head and substrate potentials.

For example, a substrate with a voltage of ±1 to ±20 kV relative to the spray head, an electric field enhancing electrode with the same voltage as the substrate, and a voltage of ±0.25 to +
±20 for 1okV auxiliary electrode or spray head
~50kV substrate, ±10-40kV field enhancing electrodes. This can be achieved, for example, by activating an auxiliary electrode, turning off an inductive or resistive tap, turning off the supply to the spray head or turning off a separate supply.

Adhesives and surface coatings sprayed according to the invention tend to exhibit the well-known electrostatic wrap-around effect, particularly when using auxiliary electrodes, forming at least one auxiliary electrode. and can be arranged to further enhance the above effects, for example to improve the coating of fibrous substrates, as will be discussed further below.

The auxiliary electrodes may be in a relatively complex pattern, portions of which can be controllably activated to alter the deposition pattern as desired or as the size or shape of the substrate changes. This can be done by switching the appropriate electrodes by bringing the sensor into contact with the template or the surface to be treated. Such methods are particularly useful for complex and varied deposition patterns, such as shoe bodies, aircraft or boat frames, or "printing" by spraying.

A wide range of adhesives and surface coatings can be applied with this invention (
(including application to the aforementioned substrates). These are usually sprayed as reactive polymers which are liquid at room temperature or preferably as prepolymers or solutions, dispersions or si-liquids thereof. The solution or vector may be inert or may react with reactive components of the atomized fluid.

In general, the fluid to be sprayed has a low shear rate viscosity at the spray temperature of 40 poise or less, for example 0.5 to 5 poise, but fluids with a viscosity of 5 poise or more (or 30 poise or more are also acceptable) are satisfactory. A surprising property of the present invention is that it allows for slow spraying and good coating.

The atomization temperature of the fluids can be matched to the fluids or their/their reaction rates. 0-80℃, e.g. 15-50℃
℃ temperature can be used.

Among the multi-component (usually two-component) systems applied from a single spray head or a single spray head with multiple delivery channels are adhesives and surface coatings, examples of which include barrier coatings ( For example, anti-corrosion paint for ferrous metals),
Thick coatings, paints and mold gel paints for injection molding or cold pressing, inks, paints for asphalt or cement substrates, for example for road matting.

One class of materials includes adhesives and surface coatings based on known polymers or polymeric precursors, which are typically treated during their delivery to the spray head after being atomized from the spray head. Reacts by free radical, ionic or group transfer polymerization. Surface paints of this type include the aforementioned barrier paints, thick coat paints and mold gel paints.

This class includes acrylic resins (which are typically preferred fast-reacting materials with drying, curing or gelling times of less than 30 seconds, and in some cases less than 10 seconds, at ambient temperature), unsaturated polyesters, etc. Petrocycles including olefin/acrylic copolymers, polyurethanes and polyureas, epoxies and lactams.

and thiosines.

Materials in the above classification include:

Acrylics: "Vinyls": ie, monomers and oligomers (including cooligomers) of unsaturated carboxylic acids, including acrylic acid, methacrylic acid, and itaconic acid.

Acrylic esters: monomers or oligomers (including co-oligomers) of mono- and polyols esterified with vinylic acid, such as esters of alkoxy- and allyloxy-alkanols, e.g. ethoxy-
mono- and poly-esters of diols, such as ethylene, propylene and hexylene glycol; mono- and poly-alkoxylated diols and triols, such as mono- and triols ethoxylated with 1 to 3 oxide residues; Polyester; Polyester acrylics: Polyesters with or without olefinically unsaturated groups in the polymer backbone, typically those having a molecular weight of 200 to 5000 with a terminal vinyl acid group reacted with a terminal water group.

These include the following polyester main chains. Linear alkanediol-alkanedibasic acid ester,
For example, adipic acid or terephthalic acid-ethylene/propylene/hexylene glycol/bisphenol A diol polyester; hydroxyalkanoic acid oligomer,
For example, caprolactone and hydroxyl butyric acid oligomers; and polycarbonates, such as biphenylene polycarbonate.

Urethane acrylics: Polymer backbones with terminal isocyanate groups capped with hydroxy-substituted vinyl acid ester units, e.g. hydroxy-ethyl/-propyl/-hexyl vinyl acid esters.

These include the following polymer backbones:

Di- or trifunctional aliphatic (including alicyclic)
and/or aromatic isocyanates, biurets or isocyanurates, or similar oligomers of these isocyanates, such as bi/tris-(incyanate-phenyl/cyclohexyl)methane.

Geoffres, for example polyurethanes obtained from those mentioned above with ethylene/propylene/hexylene glycol; polyalkoxylated derivatives thereof, and/or polyester diols such as those for polyester acrylics mentioned above.

Any of the above can be copolymerized with a hydroxyamine or amine to form a ureido substituted backbone.

Epoxy acrylics: Polyether backbones with terminal vinyl acid ester groups, such as those for polyester acrylic acids described above. These include at least bisalkoxylated (eg, ethoxylated) bisphenol A-based polymer backbones.

Functionalized acrylics: e.g. vinyl monomers, hydroxy-substituted vinyl acid ester groups (e.g. hydroxy-
(ethyl/propyl/-hexyl vinyl ester), a copolymer containing vinyl ester units capping hydroxyl groups or epoxy groups.

Suitable monomers include unsaturated esters in which the unsaturated group is in the acid or alcohol component, such as vinyl acid esters, and vinyl/alkyl esters such as crotonate and vinyl acetate, such as methyl/butyl acrylate/methacrylate. ; and vinylic acid itself.

The backbone can include other monomer species such as vinyl halides and vinylidene dihalides.

All of the above acrylics can be used with conventional peroxide (e.g. benzoyl peroxide) initiators and amine accelerators/acrylics.
Using accelerators, feed (acrylic + initiator) and (acrylic + accelerator) from two spray heads or thermally activate the spray (acrylic + initiator) during spraying or on the substrate. Free radical polymerization can be carried out appropriately by Conventional silicone-based catalysts (
Group transfer polymerization using eg Me2SiCN) and a fluoride ion activator can also be preferably used by supplying (acrylic+catalyst) and (acrylic+activator) separately.

Any of the solvents or vehicles for the oligomers or oligomers in all of the above acrylic acids may be inert or themselves contain vinyl or acrylic functional groups;
It may also react with dissolved, dispersed or suspended oligomers. Solvents of the latter type include "vinylic acid" esters of mono- and polyols such as N-vinylpyrrolidone, vinyl acetate, tetrahydrofuranol and ethylene glycol. Unsaturated polyester-olefinic/acrylic copolymer (2) Generally, a copolymer of a polyester having an olefinic unsaturated group in the acid residue and an olefin or vinyl acid or ester. Suitable polyester components include linear alkenediol-alkenedic acid esters. Suitable acids include maleic acid, fumaric acid, itaconic acid and mesaconic acid. Suitable glycols include ethylene/propylene/hexylene glycols and alkoxylated derivatives thereof and alkoxylated derivatives of bisphenol A. Such boss esters typically also include saturated monomers such as phthalic acid, sebacic acid and/or adipic acid and hydroxyalkenoic acid oligomers.

Suitable monomers include the monomers mentioned above for functionalized acrylics, as well as styrene and methylated styrene.

Polymerization is preferably carried out with any combination of comonomers as described above for acrylics by feeding the initiator and accelerator from separate spray heads or feed lines.

Polyurethane/Polyurea: As mentioned above in the section on urethane acrylics, polyisocyanates and polyols and/or (poly)olamines and polyamine analogs of these polyols, which react to form polyurethanes or their polyurea analogs. give rise to a body. Polymerization of the polyurethane precursor is carried out by feeding the polyisocyanate from one spray head or feed line and the polyol from another spray head or feed line. The required catalysts, such as tertiary amines and tin compounds such as dibutyltin dilaurate, may be supplied either from the spray head or from the feed line.

Polyurea precursor polymerization can be carried out in a similar manner, except that no catalyst is required.

Petrocycles (including epoxies): epoxy compounds such as epoxyalkylated bisphenol A derivatives (e.g. epoxyethylates), glycidyl esters and cycloalkene epoxides, thioepoxides such as the thio homologs mentioned above, lactones such as caprolactone, lactams , such as caprolactam and oxazolinic acid.

Ring-opening and polymerization of heterocycles fed from one spray head or feed line can be performed using, for example, amines, Lewis acids or Bronsted V (e.g. BF□, I(+) fed from another spray head, etc.). You can do it by doing this.

Thiolenic acid: Unsaturated (olefinic) materials such as those mentioned above under acrylics and unsaturated polyesters reacted with (poly)thiols. Virtually any sulfur species is suitable.

Free radical polymerization involves feeding a peroxide initiator from one spray head or feed line, an amine promoter from another spray head, etc., and simultaneously feeding olefins and/or thiols, etc. from each spray head or feed line. It is done by doing.

As a one-component system that can be applied from a single spray head,
Paints include adhesives, barrier paints, surface paints such as thick coat paints and mold gel paints, inks and paints for asphalt or cementitious substrates.

Examples of such single-component systems include the following materials (a) and (b).

(a) something that does not react during or after flight, such as a solution of a pressure-sensitive adhesive; or (b) something that reacts during or after flight, i.e. the reaction occurs externally at the spray head, during flight or on the substrate. A system started in

Pressure-sensitive adhesives belonging to category (a) above include conventional acrylic adhesives of the type based on polymers and copolymers of hydroxyalkyl vinylic acid esters.

External polymerization initiation that falls under (b) above is radiation curing, i.e., curing by irradiation such as microwaves, UV light, visible light, infrared light, electron beams, or sound waves, and anaerobic (anaerobic) curing.
erobic) adhesives and (e.g. nitrogen storage) paints, or dispersed catalysts, catalytic initiators and/or in e.g. gas masses or gases in contact with the spray.
or hardening by treating the in-flight fluid with an accelerator.

Radiation curing systems are essentially free radical curing systems in which polymerization is initiated during or after flight. All free radical adhesives mentioned in the multi-component system/
Paint materials: acrylics, unsaturated polyesters
Olefins/acrylics and thiosines can be used.

The radiation curing system also includes the above-mentioned acrylic heat-sensitive adhesives and oligomer precursors. These are usually cured on the substrate.

The single atomizing fluid described above can contain any desired hexamers and/or oligomers and conventional catalysts/initiators that are themselves polymerized by appropriate irradiation. For example, a benzene-amine type curing catalyst may be used as the U② curing catalyst.

Anaeropic adhesives and paints are typically cured on the substrate.

All the abovementioned adhesives (one-component or multi-component) may also contain customary thermoplastic components, such as tackifiers and surface-active slip agents which promote "wetting".

Figures 1 to 3 of the accompanying drawings show various embodiments of the apparatus used in the coating method of the present invention.

The apparatus shown in Figure 1 applies adhesive or surface paint to a flat substrate (
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A device for coating surfaces (for example boards) comprises a spray head 1, here comprising an electrically conductive circular capillary nozzle of the type described above. 15-2
An annular field-enhancing electrode 18 with a diameter of 5 mm+ is provided 20 mm below the nozzle 2 and coaxially with the nozzle 2. This electrode has a dielectric strength of 15kV/nn and a volume resistance of 5X10
11~5X1013ohm-an and knob size 0.75~
It consists of a core of conductive or semi-conductive material sheathed in 5 m of material.

The spray head 1 is mounted directly above a flat substrate 3, which can be, for example, a generally rectangular piece of cardboard perforated in the knock-down format of a box, a conveyor belt, a movable textile web or on a length of paper wrapped between a drum or mandrel 4.4 (not shown).

When it is required to form a pattern of adhesive on a substrate, the spray head 1 is moved by a robotic arm or gantry (
gantry).

A field electrode 5 behind the substrate 3 allows full control of the spray pattern to be applied to the nozzle 2. This is not necessary if this can be accomplished by adjusting the electrodes 18 and their relative positions and, if necessary, using (other) auxiliary electrodes. If used, the field electrode 5 should be of the same shape as the desired spray deposit 9, e.g. a rectangular metal plate for strip deposits on a web, or a patterned metal plate for adhesive patterns on a box. Preferably, it is a metal plate as described above.

The nozzle 2 is connected via a line 7 with a pump 8 to a reservoir 9 of the material to be sprayed.

The device of FIG. 1 can be used as a single nozzle device for the aforementioned one-component systems, such as pressure-sensitive adhesives or radiation-curable adhesives or surface coatings.

When used in this manner, the spray head 1 and electrode 18 are charged to the aforementioned operating voltage. If the substrate 3 is a mobile web, it is set to move.

The spray liquid, for example a polymer solution, is passed from the reservoir 9 to the nozzle 2.
is pumped there into atomized droplets 10 charged to the same polarity voltage as the nozzle 1 with respect to the substrate 3, and is atomized into an annular field-enhanced IX! 18 and is absorbed in the direction of the substrate. These droplets impinge on the upper surface 11 of the substrate 3 in the strip 12.

If the substrate 3 is to be sprayed with surface paint, the strip 12
is preferably adjusted so that it covers the entire surface 11. In the case of a moving web substrate 3, the strip 12 is continuous. When the substrate is a knock-down box, the spray head 1 is preferably moved so as to apply the desired pattern of strips of coating adhesive. The use of electrodes 18 to control the spray pattern has been described above, and the use of auxiliary electrodes to control the spray pattern will also be explained below.

If the applied fluid is a radiation curable material.

The apparatus is also suitably provided with an irradiation source 13, such as a UV clamp infrared heater or a hot gas stream. If the fluid is a surface coating, the radiation source 13 is arranged to irradiate the substrate 3 at the point of contact of the spray 10 or at the point of movement of the coated substrate 3.
It is often preferable to place If the fluid is an adhesive, the position of the spray head 1 or the sprayed material 10
It is clearly preferred to initiate the reaction in the radiation source 13.

The entire area of atomization, i.e. spray head 1 electrode 18
, the spray 10 and the substrate 3 can be enclosed by a container 14 if necessary. By enclosing it, unwanted spray streams can be eliminated, and also.

Inert atmosphere required for some reactive fluids.

For example, a nitrogen atmosphere can be created. If necessary, the container 14 is supplied by a duct 15 to the container 14;
A gas flow within the container that is evacuated through port 17 can be purged and can assist in the transfer of spray 10 to strip 12 on substrate 3.

The gas stream can effectively reduce the loss of inert solvent from the spray 10, especially if the gas stream is hot, such a warm or hot gas stream can be used as a thermal initiator for adhesives, for example. Can be done.

If necessary, an auxiliary electrode 6 used to control the spray pattern is placed at a suitable location 1, for example on the side of the spray area comprising the spray head 1 and the substrate 3 and/or behind the substrate 3, generally can be provided at a location 80 mm or more from the spray head 1.

For example, by suitably selecting the voltage and using auxiliary electrodes, it is possible to focus or diffuse the spray 0 onto the substrate 3. (If a container 14 is present, it can also be wrapped in the container, and part of the container itself can be used in its entirety as an auxiliary electrode.) Once sprayed with surface paint, the substrate 3 moves out of the spray area. hardened.

If the substrate 3 is a knock-down box that has been sprayed with adhesive, the box is typically transported to conventional packaging assembly equipment, assembled into a box, and the sprayed surface is bonded to the other sides of the box. The adhesive is cured upon contact.

When using the components listed below, the apparatus of FIG. 1 can be used to apply two-component spray head systems in the same manner. In this embodiment, however, the nozzle 2 is surrounded by a coaxial annular slot 22 as described above, and the slot 22 is connected to the pump 28 by a second line 27.
It is connected to a storage tank 29 (28 and 29 are not shown). Reservoirs 9 and 29 each separately contain two components, such as (acrylic + initiator) in 9 and (acrylic + accelerator) in 29. A 1:1 volume ratio of the discharges from the two nozzles is preferred, but any ratio that produces a suitable reaction can be used.

Of course, the irradiation source 13 is necessary in this case. The method of spraying in all other embodiments is essentially the same as described for single nozzle application.

FIG. 2 shows a modification of the spray area of the apparatus of FIG. 1 for applying a surface coating to a fiber substrate 1, such as a silicon-based optical fiber or a plastic-based optical fiber. The arrangement of the spray head 1 and the substrate 3 is not critical;
and FIG. 2 show a top view and a bottom view, a side view and a top view, or a side view and a bottom view, respectively, according to this arrangement.

The modification in FIG. 2 is that it is the same type of spray head as in FIG. The point is that it has the same type of annular electrode 18 provided as shown in FIG.

The spray head 1 is mounted above or to the side of a grounded fiber bundle 3, which itself is preferably supported essentially neither horizontally nor vertically.

In the spray head 1 in the spray area, the electrodes and the fiber bundle 3 are surrounded on three sides by a grid-shaped auxiliary electrode 36.

The remainder of the apparatus (not shown) is essentially the same as that described in FIG.

In use, fluid is pumped and atomized by the spray head 1. The poles 18 of the spray heads 1 and ' are charged to the aforementioned operating voltage and the fiber bundle 3 is drawn through the spray area.

Because of the "'wrap'" effect seen in electropower spraying, by adjusting the voltage, size and configuration of the nozzle 2 and electrode 18, their relative position, the rest of the device and the fiber 3, the surroundings of the fiber can be adjusted. It is possible to apply a suitable coating around a sufficient portion of the material. If a misalignment or a more uniform coating is required, the spray head 1 may have single or multiple slots (2 or 2.22.
221) may be used, or a concavely curved spray head may be used, or a spray head coaxial with the fiber bundle 3 (two-rod electrode 1 of a corresponding shape) may be used.
8), or an auxiliary electrode 36 may be used,
By adjusting the voltage, the spray 10 can be bent around the fibers to the point where it fans out and is not facing the spray head 1 as shown.

Besides the use of auxiliary electrodes 36, similar or identical spray heads 31 and electric field reinforcement? 1 further along the fiber bundle 3 on the opposite side of the fibers 3 and at a sufficient distance from the first electrode 1, it is possible to increase the coating where it is lacking or absent. can.

Figure 3 shows the components of a two-component system placed on a flat substrate (for example, a board).
1 shows an apparatus with two spray heads for separate application of The apparatus is generally similar to that of FIG. 1, and the type of substrate 3 and the method of supplying components to the substrate are the same.

However, the device of FIG. 3 has two separate spray heads 1 and 3I consisting of conductive capillary nozzles 2 and 32, respectively, and electrodes 18 and 48, respectively. These spray heads are spaced far enough apart that their electrostatic fields do not interact detrimentally with earth during use. As shown, these spray heads are mounted on and on either side of the conveyor belt for the textile web substrate or substrate 3 and are arranged over the preferred mixing area directly above the substrate 3. However, as mentioned above, the two components can be sprayed simultaneously or sequentially on the same part of the substrate, or in the case of adhesives, where they can be sprayed simultaneously on different parts of the same substrate moving from one spray to the other. The mixture can also be mixed on the substrate 3 by spraying the respective components onto separate surfaces of the substrate 3 to be bonded. A suitable arrangement of spray heads 1 and 31 for such purposes will be obvious to those skilled in the art. In general, undesirable electric field interactions tend to be minimized by maximizing the spatial separation of spray heads 1 and 31.

The method of sequentially spraying the same part of the substrate is advantageous because the electric fields of the two spray heads 2 and 32 can be switched alternately. The method of simultaneously spraying different parts of the substrate 3, also moving from one spray to the other, is advantageous since the electric fields of the spray heads 2 and 32 can be separated sufficiently spatially. Both methods have the advantage of avoiding the possibility of adverse electric field interactions.

The mixing of sprays 10 and 40 is completely unsatisfactory if they are charged with the same polarity. Therefore, in order to achieve good mixing, it is desirable that the spray heads 10 and 40 have different polarities with respect to ground in use, unless the application of the spray is adversely affected. Additionally, the polarity of the spray heads may be simultaneously reversed or alternated.

Programming means for moving the spray head 1, 31 with respect to the binary fluid, such as lines 7.37, pumps 8.38 and reservoirs 9, 39 and any auxiliary electrodes 6 and 36 (all not shown) therewith; Other properties of the device are essentially the same as in FIG. Of course, neither irradiation source 13 is necessary.

The method of use of the apparatus is essentially a twin nozzle application as described with respect to FIG. 1, except that the two components may be applied simultaneously or sequentially.

Thus, for example, n-tanks 9 and 39 can contain (acrylic + initiator) and (acrylic + accelerator) separately.

With reference to FIG. 2, from one spray lO to a second spray 40
The method of simultaneously spraying different parts of the fiber bundle 3 moving to the fiber bundle 3 has been described in connection with single nozzle single fluid and twin nozzle spraying. 2 clearly the same type of arrangement 2 nozzles 2
It can also be used for component spraying. It is obvious how to modify such an arrangement to achieve in-flight mixing, simultaneous application and sequential application to the same part of the fiber bundle 3.

Next, the present invention will be further explained with reference to Examples.

Typical spray rates in the following examples range from 1 to 3 aj/see per slot nozzle.

Using the apparatus shown in Figure 1, which has one slot nozzle, four Q-panel type S (polished surface) steel sheets were heated in two reactive solvents. urethane acrylate resin and further containing 2% w/li benzophenone-amine photoinitiator and 0.5% w/li surface active slip agent (Eberryl 350-acrylated siloxane). Coatings were done using different sprays. All coatings were greater than 100 microns thick and were removed from the spray area and U, V, cured. Cure time is approximately 4 minutes at room temperature.

All resins consist of aromatic urethane oligomer backbones (optional chain extension with polyethylene oxide chains) with terminal isocyanate groups capped with 2-hydroxyethyl methacrylate.
dar 804.805 and 806 (ICITM).

The reactive solvents used were ethylene glycol dimethacrylate (CGDMA) and triethylene glycol dimethacrylate (TEGDMA).

Spray solution viscosity (Bruchfield, 20°C) is 0.8
~7.2 voices. Surprisingly, using this device, TEGDl'1A8 with a viscosity of 7 poise
05 solution could be sprayed.

Using the equipment, solvent, solvent ratio and method of Example 1, the printed guide sheets were coated with a 5 micron thick U, V, cured coating based on ICI bisphenol-A epoxy acrylate resin. A smooth overprint varnish film was obtained.

The device described in Part A and Main Example 1 is similar to that in which the brown paper belt between the motor-driven roller and the feed roller is CGDed using the triple-slot twin nozzle type device described above.
Coated with a Modar 804 solution in MA (40% solution containing 100 ppmw benzoquinone, viscosity - Bruchfield 20°C - 2,3P). The same volumes of A and B containing the following additives A and B were placed in two storage tanks (first
9 and 29) in the figure.

A: 4% W/- benzoyl peroxide (BPO) B
: 1.2% Eber/N-dimethyl para-toluidine (DMPT) and 2% w/w surfactant (Eber
ryl 350).

The above two components were sprayed at equal flow rates.

The gel time for these coatings was approximately 45 seconds, and gelation was completed in 45 seconds.

Using the apparatus of Example 3 on steel and glass sheet substrates on brown paper belts, the still and glass sheets were treated with urethane acrylate (similar to 804 and aO5) and tetrahydrofuryl methacrylate using the method of Example 2. IC inside
I reference 835 (as chain extender) 3% V/- Dalt
(contains ocel F 2805 polyester thiol)
solution (viscosity - Bruchfield, 20°C - 4,0 boise). In this component system A: 3%-/w BPO B: 3% w/w DMPT and 3% ty/w Eber
Ryl 350.

The curing time of this paint was approximately 4 minutes.

Methacryloxyethyl phosphite (1-3% WOW,
Adhesion promoter) was added to B during further coating of the steel sheet in the above method with comparable effectiveness.

Lesson 1 a) Using the apparatus of Example 3 with two board substrates on a belt, the two substrates were treated with urethane acrylate resin in two different reactive solvents, i.e. , 2-hydroxyethyl acrylate (50% W/W) or a mixture of ethoxyethoxyethyl acrylate and 1.7.3-trimethylolpropane triacrylate (1:1-8)
aliphatic (isophorone) with a terminal isothiaphor l-group capped with 2-hydroxyethyl methacrylate
Diisocyanate-polypropylene diol (M, wt
, 1200) to a thickness of 30 microns.

A: 1% ty/w [1PO B: 1.5% ty/u DMPT (Respective gel times for the two systems were 14 seconds and 22 seconds.) The coated board in both cases was removed from the spray area. It was quickly removed and immediately overlapped with an identical but untreated board. The adhesion that developed after a suitable gelation time was such that when these boards were pulled apart, separation of the board fibers was observed rather than failure of the adhesive layer.

b) Repeat a) above using the above solution in 2-hydroxyethyl acrylate solvent, but with A:2
% w/w BPO and B: 1.5% w/w DMPT. Gelation time was 7-9 seconds.

When another board was laminated and peeled off after gelation, severe peeling of the board fibers was observed rather than destruction of the adhesive layer.

Using the apparatus of Figure 3 with two single slot nozzles set to spray in two spatially discontinuous areas, two board substrates were coated with the 2-hydroxy of Example 5a. Ethyl acrylate i8m A and B were spray applied separately to 30 micron thick coatings.

When the boards were laminated and peeled off after a 14 second gel time, significantly worse board peeling was observed than in Example 5a.

When the above method was repeated using other A and B solutions from Example 4a, the same effect on adhesive bond strength was observed.

[Brief explanation of the drawing]

1 to 3 show various embodiments of the apparatus used in the coating method of the present invention. 1 Spray head 2: Nozzle 3: Substrate 5: Field electrode 7: Line 8: Pump 9: Storage tank 10: Engraving of spray drawing (no change in content) Fig, 7° Fig, 2a, Fig, 2b. Procedural amendment (method) August 27, 1986

Claims (1)

[Claims] 1. A method of applying a fluid which is an adhesive or a surface coating or a precursor thereof by spraying, by supplying said fluid to a spray head and placing said fluid in a strong electric field, thereby: displacing the fluid from the spray head under the action of an electric field to form a spray;
A method of spray application of a fluid, characterized in that the electric field is enhanced by a charged electrode adjacent to the spray head. 2. The method of claim 1, wherein the fluid is a mixture of multiple fluid precursor components of a multicomponent adhesive or surface coating. 3. The method of claim 1, wherein the fluid comprises at least one, but not all, of the components of a multicomponent adhesive or surface coating. 4. A method according to claim 1, wherein the fluid reacts with itself or with another fluid during or after the flight. 5. Claim 1 in which the reaction is initiated by irradiation
The method described in section. 6. The method of claim 1, wherein the fluid comprises a polymer or polymer precursor containing unsaturated carboxylic acid monomer units. 7. A method for applying by spraying a plurality of fluid precursor components of a multi-component adhesive or a multi-component surface coating, the method comprising: supplying said fluid to the outlet of a spray head having a plurality of outlets; is placed in a strong electric field such that the fluid is moved from the spray head under the action of the electric field to form a spray and the fluid mixes as it moves on or from the spray head and the electric field 2. A method as claimed in claim 1, in which the step is enhanced by a charged electrode adjacent to the spray head. 8. The method according to claim 7, wherein the fluid reacts during or after flight. 9. Process according to claim 7, wherein the reaction is initiated by a catalyst or a catalytic initiator and/or promoter. 10. The electrode consists of a core of conductive or semiconductive material and a sheath material sheathing the core, the sheath material having sufficient insulation to prevent sparking between the electrode and the spray head. A material having a yield strength and a volume resistivity and a volume resistivity low enough to conduct charge collected on the surface of the seed material through the seed material to the conductive or conductive core. The method described in Section 1.