JPS5978241A - Plastic substrate and method and apparatus for coating substrate with high polymer - Google Patents

Abstract

(57) [Summary] 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 coating substrates, particularly preformed plastic substrates, and barrier coatings for plastic containers. For example, a polyethylene terephthalate bottle is coated with a polyvinylidene chloride copolymer and the bottle is covered with a gas barrier coating. That is, conventional airless spray equipment is used to form a high quality, uniformly transparent barrier coating on the surface of a polyethylene terephthalate container to substantially reduce or prevent gas passage through the container wall.

Plastic beverage containers (usually called PIB T bottles) made of polyethylene terephthalate are
They have become popular for a number of reasons, including light weight, strength and ability to hold beverages including carbonated beverages such as soft drinks and colas, non-toxicity, and inexpensive materials and container manufacturing methods. Typically, these containers are formed by a "blow molding" process in which a preform, or parison, is heated, placed in a mold, and pneumatically stretched axially and radially into the desired container shape. This kind of biaxially distracted PE
T-containers are durable and have excellent creep resistance. In other words, even if the internal pressure increases due to the gas in the liquid inside the bottle, it maintains its original dimensions. Additionally, the relatively thin wall thickness allows it to withstand the internal pressures exerted by carbonated beverages such as soft drinks and colas without undue distortion over the desired shelf life, despite its light weight.

However, a major problem with this type of thin-walled P1gq゛9 container is the permeation of gases such as carbon dioxide and oxygen. That is, when using a PET container, these scum are not allowed to enter the container. The pressure difference between the scum and the outside pressure causes it to move or pass through the container wall. Thus, when you fill a bottle with carbonated water, the pressurized carbon dioxide (usually 60 to 75 pounds per square inch cage (psig)) in the liquid pressure) is released through the vessel wall.

As the carbon dioxide migrates over a period of time, the carbon dioxide in the carbonated water gradually decreases, and when the bottle is opened, the carbonation of the drink has diminished, leaving it in what is known as a ``drunk'' state.

Conversely, PET containers allow oxygen to easily pass through them, so oxygen from the indoor air can enter the container through the walls, damaging food items inside the container that are susceptible to deterioration when exposed to oxygen, and reducing the flavor and quality of the contents. spoil.

Currently, one carbonated soft drink manufacturer is offering
Reduce the pressure loss inside the T-bottle to 15% or less (for example, if the initial pressure is 6%)
If it is 0 psig, it is necessary to keep it below 9 psig). This is referred to as "shelf life" (i.e., the ability of the bottle and contents to be kept for a long time before sale without reducing the quality of the product below acceptable limits). With uncoated PET bottles, delivery time to the point of sale can exceed the shelf life in up to half of the United States.

The problem of air permeability in PBT bottles or containers is particularly acute when the relatively small size of the container results in a higher ratio of container surface area to volume of contents than larger containers. One example is a half liter size container, which is the desired size for soft drinks and carbonated beverages such as colas.

For the reasons stated above, 1. Due to the low vapor and gas permeability, it has been found desirable to coat PET containers with a layer of material that forms a barrier to prevent ventilation on the surface of the container.

A material that has traditionally been used to form barrier coatings is a copolymer of salt 1-hibinylidene (commonly known as PVDO). This is a latex, a polymer that is coated as an aqueous polymer dispersion and dries to form the desired barrier coating. In the past, various techniques have been used to apply barrier coatings of PV]) C Rags, including PgT preform coatings, to the surface of blow-molded PET containers prior to blow molding and roller coating. ing.

PVDC! has been successfully applied to PET container surfaces by methods such as roller coating, but this type of processing method is not particularly effective or economical because it does not lend itself to high production rates. That is, since PET bottles are produced at a rate of 700 to 1800 bottles per minute, it is necessary to form P V DO coatings at a rate of 600 bottles or more per minute using an effective and economical coating method. Currently, equipment for achieving this level of productivity or higher with roller coating is prohibitively expensive.

Many polymer latex coating methods have been disclosed to date, including roller coating, brush coating, gutter coating, spray coating, electrostatic coating, centrifugal coating, casting coating, and the like. U.S. Pat. No. 4,370,368 is one example, and employs the "Leek method" as a suitable method for depositing latex on preformed plastic surfaces with a pretreatment to improve wetting properties such as a bonding layer. Among the experimental examples in the above patent, please refer in particular to the "spray coating" of latex. However, in Examples '10 and 16, for example, before spray painting with P V DO latex, the plastic bottles were first smeared to form a bonding agent. Still, for example, US Pat. No. 3,696,987 1. -g-'6,804,
No. 66, No. 4,004,049 and British Patent No. 2
．． No. 014,160 is for spray painting latex on plastic bottles. There are patents other than those mentioned above that form the background of the present invention, but although the above patents do not completely develop the prior art, they are intended to fully explain the present invention and to help clarify the differences between them. This is quoted in.

For example, U.S. Patent No. 5,804,665 discloses latex coating by rotating the coating during spraying, using centrifugal force to evenly distribute and hold the dispersant on the wall surface, and heating and melting it while continuing to rotate it. Painting issues are being addressed. U.S. Patent No. 4,004, O49 destroys the emulsion during spraying, that is, atomizes the latex and reduces its stability (destabilization), resulting in only slight drying or no need for drying yet. A sprayable latex adhesive is disclosed for the purpose of forming a bumpy grain pattern. The other patents mentioned above are related to "blow-up" coatings, but do not seem to focus on the problem in particular.

Although spray coating is said to be an effective and fast method of applying liquid coating materials to substrates, special arrangements are required when spraying polymer latex, as shown in the above patents. . Latex P using conventional equipment
It would be highly desirable if there was a method that could be applied to plastic bottles such as ET, but when spray painting pPET bottles with an aqueous PV 1) 0 polymer dispersant using the conventional spray coating method, the resulting coating is slightly homogeneous. It was found that when it dries, it does not become uniformly transparent, and the surface of the bottle becomes distorted, making it completely unmarketable. Furthermore, the pressure drop in the spray coating container is above the permissible limit. That is, as a commercial product, PVDO or other polymeric barrier coatings covering PET containers are very homogeneous, smooth, clear, uniformly transparent, shiny, and resistant to delamination and do not crack or split into small pieces. and must be substantially impermeable to gas migration.

Coated containers that do not meet the above requirements are not suitable for practical use.

Until now, there has been no way to process PET containers with PVDO that can be applied with conventional spray equipment and formed into a barrier coating that meets the above requirements.

According to aspects of the present invention, a unique method of coating aqueous polymeric latex sweeteners or dispersants on substrates 14, particularly on plastic substrates, is provided. This is accomplished by impinging an aqueous polymer dispersion onto the substrate surface, destabilizing and converting any dispersant deposited on the surface to form a gel layer with the polymer in the continuous phase. Above the gel layer is a polymer dispersed layer. Thus, the method first forms a wet, homogeneous coating of a substrate with a gel layer that adheres the dispersant to the substrate; this physicochemical state of the coating is achieved by bombarding the substrate with a stream of aqueous polymer dispersion.

The homogeneous coating is then dried and gelled through its entire thickness to fully coalesce the coating into a polymeric film.

It has been found that the desired results can be achieved using conventional airless spray equipment. However, this method is very innovative in that it uses the above device to form a polymer latex flow that does not become unstable until it hits the substrate surface, and then forms a wet film of dispersant with a lower gel layer. achieved in a way. It has been found that this definitive method provides barrier coatings with superior properties.

Additionally, the present invention provides a PVDO barrier coating having a highly glossy, virtually impermeable, crystal clear, smooth and uniformly transparent PVDO barrier coating with no cracks or cracks.
By providing a coating method for forming an ET container, 1.
) Overcomes the problem of applying PVDO barrier coatings to ET containers. The process is preferably carried out in an airless spray system that coats the T)ET container with the aqueous P V D 0 dispersant, making it easy to incorporate into high speed production processes with high coating efficiency.

According to the method of the present invention, a PET container at room temperature is closely placed in one or more airless spray nozzles, and the aqueous P V DC dispersant passes through the nozzles and impinges on the outer surface of the container, causing the A PVD c wet film is formed with an interfacial gel layer and an aqueous dispersion top layer that adheres uniformly as a film.

In a preferred bottle coating method, the gel layer is first completely adhered to all surfaces of the bottle. The gel layer then acts as a buffer or cushion against further gelation because the impact force is weakened, and the gel acts as a wet surface for the polymer dispersion upper layer. The coating is then dried and dehydrated to remove PV from the base of the interfacial layer on the PET surface. Completely gelatinize the outermost surface of the coating. Heating is then continued to film or fully coalesce the P V J) O polymer coating. Preferably, radiant heat is used to rapidly warm the wet coating to complete gelation of the coating triggered by dispersant bombardment. For details on the heating time and furnace temperature, see P.
ET Short and low enough to prevent distortion of the T-bottle. Thereafter, it is dehydrated, preferably by subsequent drying with radiant heat, to completely crush or coalesce the keel into a coating. The above steps are essential to obtain excellent barrier coating properties.

Another method of drying the film is to control the temperature and humidity to avoid dehydration too quickly.

For example, the preferred environment for drying the film is a relative humidity of 20 to 90.
% rise temperature is approximately 767C to 79.4C (1700C)
F to 175°F). About the holding time P.
Short enough to keep the ET vessel temperature below the strain temperature of about 1400 F'' and long enough to dry the coating to a substantially non-stick condition. The resulting coating is very It has a homogeneous, smooth, clear texture, uniform transparency and shine, is resistant to delamination, has no cracks or microcracks, is virtually air-free, and can withstand pressure for up to 16 weeks. It meets the "shelf life" standard of keeping the water content below 15%.

When the present invention is practiced, a stable dispersion of polymer particles in water impinges on the container surface and becomes unstable on the container surface. This stale dispersion converts into a thin gel layer at the interface with the surface.

This gel layer has a polymer in the continuous phase and water in the continuous layer. The thin gel layer flows out and serves as a base for evenly adhering the polymer dispersant to the surface without sagging or interruption. In this way, the water (1) raw polymer dispersant adheres to the surface of the container (=J) through a sticky gel layer, adheres closely to the gel layer, and forms a non-converted dispersed layer (2) of polymer particles. The thicknesses of these layers vary, but for example, if the total wet film thickness is 4 to 24 microns, the gel layer is 2 to 12 microns, with the unconverted dispersion layer accounting for the difference. It is believed that there is a gradual exchange of material between the gel layer and the aqueous dispersion top layer.Although the invention is not limited to the precise physical relationship of these layers, selective destabilization of the dispersant at the surface may result in substantial It has been found that it is important to impinge the dispersion stream on the surface so as to form a gel layer, and that the gel layer performs several important functions that differentiate the method of the invention from conventional methods. First, the polymer dispersion is quickly and effectively applied using conventional spray equipment to provide sufficient adhesion to the substrate for uniform wet coating, and at the interface with the surface, the dispersion is applied as the coating dries. Continuous conversion of the agent into a complete gel layer allows coalescence into a homogeneous polymeric film with excellent adhesion and barrier properties.

It has been demonstrated that a critical gel layer can be obtained by bringing the bottle surface into close contact with an airless spray nozzle in cooperation with the pressure of the liquid stream to impact the PVDO coated latex onto the container surface with a sufficiently strong impact force. However, it has also been demonstrated that complete atomization or spraying in the traditional or industrial sense does not achieve the same results as the present invention. It has been found that even complete atomization over the distance required for spraying (=J) using an airless spray nozzle is insufficient to achieve the objectives of the present invention. In such circumstances, the atomized particles The particles reach the substrate with insufficient energy to collide and form a gel layer, collect on the surface and form a bumpy film, resulting in poor barrier properties when drying. If the dispersant is applied without bumping using the above method, not only will the dispersant not be properly wet, but the viscosity will be 1! (because of this, it will flow out and be deposited unevenly on the surface. Once the desired result has been achieved, the latex stream from the airless nozzle spray will either attempt to break up the airless nozzle or break up so much that it will not be completely atomized. They form threads or droplets and reach the substrate surface with a force that causes a phase inversion at the surface.Therefore, one stream of an aqueous polymer dispersion is defined as a gel layer in which the impact force causes the dispersant to develop as described above and forms the interfacial layer. means continuous liquid broken threads, fibrils or droplets, provided that they are sufficient to convert into

If the phase is inverted away from the nozzle and before reaching the surface, the coating will be rough or mottled, will not coalesce uniformly when wet, and will not provide a good barrier customization after drying. Similarly, if there is no phase inversion during spraying, the result will be similar. Conversely, good results are obtained when the stabilizing polymer dispersion impinges on the surface with sufficient force to selectively destabilize it. That is, a gel layer is formed which becomes an interfacial layer between the substrate and the polymer-dispersed upper layer. It has been found that this type of coating construction results in a high quality coating that wet-adheres and, when dry, provides a continuous film that coalesces and binds to the substrate.

Thus, practice of the present invention results in a clear, uniformly transparent PVDo barrier coating on a P'ET container. P V I) O coating material fills a vessel with an initial pressure of 60 psig to about 23 tll? (73F) and 50
The coating is applied at a thickness sufficient to meet the requirement of a pressure drop of less than 9 psig when stored for 16 weeks or longer at a relative humidity of 1.5% relative humidity. Dow Chemical Company (
1) Philip Tee Truss of ow Ollemical Co., Midland, Michigan.
Pb1llip 'I', I)eLassus),
Donald O.L. Clark (1) onald L, C
1arke) and Ted Kos (1,'cd Co5
5e) Co-authored “PET Bottle Nosaran Coating (5ara
n Coatings of PET Bottles
): Applications, Durable Dust and Recycling (Applicat
ion.

1'ermanence and I also cycle
) J for a paper with approximately 0.01 to 0.02 mils (approx.
It has been reported that PVI) O coatings having a thickness of 5 to 5 microns) satisfactorily meet the above specifications. Currently employed coating thicknesses are about 2.5 to 12 microns, preferably about 8 to 9 microns.

The present invention is amenable to coating containers in batch or continuous methods (coating and drying containers in continuous motion). Alternatively, alternative means of exposing the outer surface of the container to be coated to an airless spray stream of P V DO coating material can also be used. In one method, the container is exposed to Rotate to completely coat the outer surface to be coated.

An alternative method, instead of rotating the container, is to orient a number of nozzles so that the entire outer surface of the container is exposed to the material.

Among the many advantages of the present invention, among other things, passing a series of P g i'' containers through a continuous coater at coverage rates of 600 lines per millisecond or more allows for very efficient and significantly high throughput. The great advantage is that PvDc coatings can be applied to PE'r bottles by collecting the overspray and pumping it back into the spray nozzle.
It is carried out in an enclosure which makes it possible to achieve a transport efficiency of 10%. The resulting coating is virtually impermeable and transparent;
It is smooth and has uniform transparency, and is resistant to cracks, small cracks, and delamination. In short, the present invention
Plastic substrates, especially PET bottles, are PVD
Although a method is provided for coating with an O-barrier coated IN to form a coating with vague physical properties, the method can be carried out at a production rate suitable for practical use.

The present invention will now be described in detail with reference to the accompanying drawings.

According to one aspect of the invention, the method uses an airless spray nozzle to coat a room temperature JET container or bottle with an aqueous dispersion of polyvinylidene chloride compound. As mentioned above, the term "dispersant" includes emulsions, solutions, and latex, and refers to fine polymer dispersants with a size of, for example, i ooo to 2000 angstroms, dispersed in a continuous phase mainly composed of water. ing. Typically, the proportion of polymer solids in the dispersant ranges from 4o to 60ff.
i, t percent. As a copolymer emulsion suitable for the present invention, W.R. Brace Co., Ltd. (戊1b).

Dalashi (DA
ILAN) 820, Dow Chemical/L, Inc. (I)o
wCbemical Company) (Mishikanz, Mitstrand), commercially available from Dow (DEW)
) X D30563.2. Morton Chemical Company (M
Orton Obe+i+icalCompany)
Morton 5erfene (Crystal Lake, IL), commercially available from
) 2011. and Union Oil Co.
Union Chemical Division of Oil Company
) (Anaheim, Calif.), both latexes are vinylidene chloride copolymers containing trace amounts of lower alkyl (methyl or ethyl) acrylate and acrylonitrile comonomers. is the main component. These polymers usually have a molecular weight of 99 to 70
Preferably from 69 to 75 weight percent of vinylidene chloride, from 1 to 60 weight percent, preferably from 4 to 25 weight percent of at least one acrylic or methacrylic monomer and optionally of the total amount of vinylidene and acrylic monomers. 1 [].

Each part by weight contains up to 100 parts by weight, preferably 50 parts by weight, of the ethylenically unsaturated monomer. The above-mentioned polymers include vinylidene chloride acrylonitrile copolymer, vinylidene chloride acrylonitrile methacrylonitrile copolymer, vinylidene chloride methacrylonitrile copolymer, vinylidene chloride acrylonitrile glycycyl acrylate copolymer, vinylidene chloride acrylonitrile glycycyl methacrylate copolymer, Viniridene Acrylonitrile Acrylonrille Acrylic Monogla Coalescing, Viniriden ethyl Acrylate Glythyl Acrylate Coalition, Vinyl Denyl Metacrylate Stayrene Coalition, Viniriden Acrylonitrillstylene Coalition, Viniridene Acrylonito chloride Liltrolololoethylene coalition, vinyl chloride vinyl chloride There are vinylidene chloride acrylonitrile methacrylic monoglyceride trichloroethylene copolymers, and vinylidene chloride methox-diethyl acrylate methyl acrylate trichloroethylene copolymers. Other coating polymer latexes or dispersants with high styrene content, preferably 60 percent or more styrene units, alkyl or aryl esters of unsaturated carboxylic acids such as acrylates and methacrylates, acrylonitrile and methacrylate trile, etc. styrene-butadiene or styrene-alcohol acrylate copolymers consisting of unsaturated nitriles, vinyl halides such as vinyl chloride and vinyl bromide, and vinylidene chloride;
There are latexes based on vinyl acetate. Polyvinylidene chloride latex is particularly valuable because it contributes significantly to air resistance, has excellent adhesion, and looks good. The proportion of vinylidene chloride in the copolymer is preferably about 70% or more, and other monomers such as vinyl chloride,
It can be composed of acrylates or methacrylates or unsaturated organic acids such as acrylic acid, methacrylic acid, itaconic acid and fumaric acid.

Plastics which serve as carriers or substrates for the coating composition include, for example, polyolefins such as high-density and low-density polyethylene and polypropylene, polystyrene and styrene-acrylonitrile copolymers, polyvinyl chloride, vinyl chloride copolymers, polycarbonates, polyacetals, polyamides and polyamides. It is made of polyester such as glycol terephthalate.

Any plastic bottle formed of a melt-formable thermoplastic resin by injection molding, blow molding, biaxial stretch blow molding or draw forming may be made of, for example, low density polyethylene, medium density polyethylene, high density polyethylene,
Olefin type copolymers such as polypropylene, ethylene propylene copolymer, ethylene butene copolymer, ionomer, ethylene vinyl acetate copolymer and ethylene vinyl alcohol copolymer, polyester such as polyethylene terephthalate (I' E 'l' ) , polybutylene terephthalate and polyethylene terephthalate isophthalate, polyamides such as nylon 6, nylon 6.6, and nylon 6.10, polystyrene, styrene-butadiene block copolymers, styrene-acrylic [conitrile copolymers, styrene-butadiene-acrylonitrile copolymers] Styrene-type copolymers such as polymers (ABS resins), vinyl chloride-type copolymers such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, polymethyl methacrylates such as methyl methacrylate, ethyl acrylate, and -t copolymers and can be used as plastic bottle substrates made of acrylic copolymers and polycarbonates.

Certain material compositions have a surface tension that makes it difficult to wet the substrate. In such cases, pretreatment by well-known methods including flame treatment and corona exposure may be used to wet the area. By closely positioning the container to one or more airless spray nozzles and directing the dispersed stream emitted from the nozzles onto the surface of the container,
Apply a coating to the outside of the PET container. It is desirable to maintain the relative humidity in the coated area of the container at 90% or higher. This is achieved, for example, by spraying water onto the walls of the coating chamber or by injecting steam into the coating area through a nozzle, whereas continuous coating equipment collects the overspray and pumps it back into the nozzle. If the substance is to be diluted with water, the emulsion can be sprayed onto the coating chamber walls or onto the coating area during the coating process, as well as onto the bottle (pvl).
It is desirable to maintain the desired relative humidity within the enclosure without diluting the O coating material. By maintaining the relative humidity in this manner, the nozzle can be kept at a minimum. By keeping the relative humidity above 90%, the coating within the enclosure will not dry out quickly, thereby minimizing microcracks in the coating. If microcracks are formed, gas will escape from the coating through the cracks, impairing the transparency of the coating and must be avoided.

During the coating operation, the bottle is rotated, for example at a speed of 500 to 15001' pln, so that the outer surface of the bottle is completely covered with the liquid coating material that is impacted from one or more stationary spray nozzles. By attaching the nozzle to a movable arm, the nozzle can be moved to cover a series of bottle surfaces. Furthermore, using many fixed nozzles pointing in different directions,
It is also possible to expose the bottle surface to be coated to a liquid stream or impact spray.

Regardless of the equipment used, to form a high-quality, uniformly transparent PVDo coating on the PEi" bottle, the PVDO stream or impact spray uniformly coalesces the polymer, i.e., the gel layer. It is important to ensure that the bottle is struck with sufficient force to form a uniform coating with the desired properties.

In an airless spray applicator, the impinging force of the liquid spray stream hitting the bottle surface is a function of water pressure, nozzle dimensions, bottle rotation speed (if rotating), and distance between the bottle surface to be coated and the nozzle surface. It turned out that.

It has also been found that when all variables of the song are equal, placing the bottle close to the nozzle produces better results.

The validity of the above discovery is demonstrated in the following experimental example.

Example As shown in FIG.
4 and the open end was held by screwing the gap end into an end cap 16 attached to the end of the spindle 12. Two airless spray nozzles 18 and 2o were installed on the wall of the painting room 14. Regarding the nozzle, please use Nordong Co., Ltd.
A 6/12 nozzle (iτIS part number 710244) manufactured by dson Corporation (Amherst, Ohio) was used. These nozzles are 0 per second
．． 06 gallons (0,2271Jtutle) (water flow rate 5
00 psig) and approximately 25.4 cm (10 cm) away from the nozzle.
o. Form a 12 inch wide fan.

Operate the nozzle without the aperture, still tilt the upper nozzle 10 degrees downward horizontally so that the nozzle openings are vertically separated from each other by approximately 1146 α (approximately 45 inches), and lower nozzle 2.
Tilt 0 8 degrees horizontally and make A2.

By arranging it in this way, the distance from the bottle surface and the top to the bottom of the bottle is approximately 2.54 cm (approximately 1.
/H) wide band-shaped coating area (approximately 1Z7scm (approximately 7
The dispersion flow was approximately perpendicular to the bottle height (1 inch) and overlapped by about 1 inch in the middle of the bottle.

Spindle 12 was turned to rotate bottle 1o at 500 rpm and nozzles 18 and 20 were activated for 200 milliseconds to apply the spray coating material.

To demonstrate the effectiveness of placing the bottle close to the nozzle, tests were conducted with the bottle separated from the nozzle by a considerable distance. FIG. 1 shows the state in which the emulsion stream is impact sprayed onto the bottle. In this case, the bottle is approximately 6.551 mm from the nozzle (
(approximately 25 inches) apart (within the scope of the present invention) and W.R.Brace No.

820 PVDO emulsion is used and the pressure is 650 psi.
g, exposure time 200 ms, and rotation speed 50
0 rpm.

Figure 2 shows the bottle 15 times after coating and before drying, at which stage it has a nearly uniformly applied wet emulsion layer (usually 4 to 24 microns thick). There is.

The structure of this layer has been found to be important in explaining the invention. It consists of a thin gel-like polymer film at the interface between the coating and the bottle. This gel film is characterized by a nearly continuous polymer film rather than individual particles.

As the emulsion layer develops outward from the bottle surface, the gel layer emulsifies -! or dispersed polymer, - transformed into an upper layer consisting of particles. It has been determined that this thin gel layer serves at least two important functions. The gel layer at the bottle interface provides the basis for adhering the coating film to the bottle surface to form a barrier coating with substantially superior properties. Upon controlled drying (preferably using radiant heat) the gelation of the top layer is completed/ζ, the polymer film base created at the interface - the entire top of the coating has the same properties as the underlying interfacial layer. It builds up to the next o until it becomes a gel state. The exact mechanism by which the entire coating turns into a gel is not fully understood, but it occurs when the coating dries rapidly.

However, it has been determined that a gel layer is essential for the coating to adhere to the bottle surface without run-off or undesirable sagging and for complete gelling as water is continuously dehydrated from the wet coating layer. At the end of the drying cycle, when nearly all of the water is removed from the gel-state coating, the polymer particles coalesce and the coating composition becomes a film. FIG. 5 is a graph representing the drying process for a wet film consisting of two layers of impact gel and emulsion according to the invention.

FIG. 6d1 shows the second hotlet 22 spaced approximately 1146 cTrL (45 inches) from nozzle +8; Th and 20 during the coating process, but all other conditions are the same as in FIG. Comparing FIG. 1 with the Oro diagram, the impact force of the emulsion flow hitting the surface of the bottle 10 in FIG. 1 is considerably stronger than in the Fang 6 diagram. In other words, in Fig. 1, the water 1 raw dispersion flow emitted from the spray nozzle strongly [washes
In Figure 6, the bottle surface is exposed to a light mist, which can be characterized as being washed. That is, FIG. 3(t) shows the conventional technique of blowing through and atomizing emulsion latex or dispersant, and this type of method cannot achieve the advantages provided by the present invention.

It has been found that it is important to direct the aqueous dispersion stream onto the substrate and impact it with sufficient force to destabilize the emulsion coating at the interface and form a gel film solid of the emulsion at the interface as described above.

Blowing is understood as atomizing. Conventional atomizing or coating does not generate sufficient impact forces to form a significant interfacial gel layer. Therefore, an airless spray nozzle was used, but conventional atomization or spraying, as demonstrated in the diagram, promotes destabilization of the emulsion, and then during limited drying, complete coverage of the entire coating. There is not enough impact force to form an interfacial gel layer that forms the basis of the gel ratio and ultimately coalesces the polymeric film solids completely.

Rule 1, especially when looking at the flow of the polymer emulsion as it exits the nozzle, this is essentially continuous for a short period of time;
It can be applied as a strip of liquid about 1.271 to 254 centimeters (about 0.5 inch to 254 centimeters) long. The fluid is not discrete when it first leaves the nozzle, but after that it is approximately 6
．． The small fibers M:脣/ζ are discrete in length from 81 to 5.08α (approximately 1.5 to 2 inches), and as the flow protrudes farther from the nozzle, the small fibers M:脣/ζ are broken into fine filaments, and as they move further away, Atomizes into small droplets. It was found that the results obtained in the present invention could be achieved by using the nozzle of Experimental Example 1 under similar conditions with the nozzle and the bottle base separated by about 25·1 t,'m (about 1 inch). That is, about 2.
s 4 cn> (approximately 1 inch) away, the liquid stream begins to disperse and continues for the next approximately 3.81 cm as shown in Figure 1.
~6.35 cm (approximately 1.5 to 2.5 inches) with mostly small fibers='? (1: Or become filamentous but not atomized particles. The effect of the present invention is achieved at a point of about 635 crn (about 25 inches). Sixth
As shown in the figure, if the substrate is further away from the nozzle, the particles will not atomize and collide with the target, but they will also not be able to wash the bottle surface with water pressure and form an interfacial gel film. The present invention does not limit the specific point at which the flow emitted from the nozzle becomes continuous fibrils or disperses into particles; what is important is that the flow impinges on the bottle surface and It is the formation of an interfacial gel layer that plays a major role in achieving the benefits. Although this may be associated with emulsion condensation using conventional techniques, as the present invention demonstrates, spraying to the extent that atomization is achieved does not generate the impact or hydraulic cleaning forces necessary to destabilize the emulsion. Therefore, I think that a gel-like polymer film layer is not formed at the interface of the bottle. From this point of view, the present invention can be said to be a novel method for forming a barrier film by bombarding the bottle surface with a water-based polymer dispersion stream.

Looking at Figures 1 through 5, it can be seen that when the bottle is placed away from the nozzle (the spray contacts the bottle surface, but there is insufficient impact or shear force to cause uniform coalescence of the polymer coating). It can be seen that there is a difference in the effect when the bottle is placed close to the nozzle so that the airless spray stream hits the surface. "Causing uniform coalescence" means that a gel film is formed at the bottle interface upon collision of the aqueous polymer dispersion stream. In other words, this is Experimental Example 10
This is a description of the procedure and the same phenomenon that occurs when carried out in the manner shown in FIG.

The following table shows the results of various tests comparing the appearance of half-turtles coated at different distances. (”
In both cases, the bottle was continuously rotated around a hot plate (by heating with radiant heat for 11 minutes, the coating was dried and made non-sticky).

Regarding the hot plate, it is approximately 315.6” at room temperature.
G (600°F) and hold the bottle on the plate surface at the ladle 889~IO,16C side (approximately 6.5 inches to 4 inches) until approximately 1
It was rotated between 0 and 6 Orpm. Thermocouples centered at points approximately 262C1r and 10.16F (6 inches and 4 inches) above the plate surface will produce temperatures of approximately 70C (70C), respectively.
158°F) and approximately 65°C (149°F).

As shown in Table 1, the arrangement is relatively close to the spray nozzle [
Samples A and B, which were coated to approximately 6.65 degrees (approximately 2.5 inches), were coated with a PVI C coating of good quality and uniform transparency with excellent appearance and uniformity. Ta. Similarly, approximately 6.35 CIIL (2,
The appearance of Sample C at a distance of 5 inches (5 inches) was slightly inferior due to the substantially lower nozzle pressure than Samples A and B, resulting in weaker spray or stream impingement forces.

) The amount of mold exchanged was all good. For a half-rifle bottle, the covered area is approximately 55 square inches. Since the density of the P V DC material is approximately 1.6, a uniformly applied 400 milligram coating would be approximately 8 microns thick (within the scope of the present invention).

When the bottle is removed from the nozzle as in Sample I]-1,
The quality of the coating deteriorates to the following level.

For example, comparing Samples A and O, the nozzle pressure and exposure time are the same, but approximately 6.356 m from the nozzle (
The coating quality of Sample A at a distance of 2.5 inches is high, while the coating quality of Sample O at a distance of about 6.5 inches from the nozzle is below acceptable limits. It should be understood that products with an appearance rating of 9 or less have no commercial value.

Therefore, nozzle D, approximately 4.5 inches away from the nozzle (location shown in Figure 6), was coated with the same nozzle pressure and exposure time as sample A, and had a relatively good coating weight. However, it has no commercial value.

Looking at the above table as a whole, it is approximately 665.2 (
Bottles operating at pressures between 650 and 750 psig (2.5 inches) apart have shown good results, with approximately 114
It can be seen that the coating on the bottles at a distance of 5.alpha.

Explaining these results, it appears that placing the bottle closely to the nozzle maximizes the force of the airless spray material impinging on the bottle surface.

This force forms a shear zone in the polymer coating material when it collides with the bottle surface, and this acts greatly to uniformly coalesce the polymer particles. It is thought that a film will form. The spraying action on the bottle is called ``hydraulic cleaning''.
Scrubbing of the coating onto the bottle surface, which can variously be described as a "scrubbing" or "shearing" action, has been found to be important in achieving the desired result.

When the above method is carried out, the emulsion stream impinges on the bottle surface, resulting in the formation of a gel layer or film at the interface between the coating and the bottle. Accordingly, those skilled in the art will be able to determine the parameters necessary to implement the principles according to a particular embodiment of the invention.

A gel film or layer of solid coating material can be seen under a microscope of 50C1 to 1000 degrees.

The gel layer adheres the emulsion to the bottle substrate and acts as a base for complete coalescence following complete coalescence, allowing the homogeneity and transparency required for excellent barrier properties to be achieved. do.

The importance of coating quality can be seen in Figures 3 and 4 by comparing two half-liter bottles side by side. The bottle on the left is coated approximately 6.35 x 2.5 inches from the nozzle, and the bottle on the right is coated approximately 11.43 cm, 4.
, 5 inches) apart. letter rAJ
is written on the back of the valley bottle so that it can be seen through the bottle. As can be seen, the bottle on the left has a coating of very uniform transparency, while the coating on the bottle on the right is mottled and uneven, making it unsuitable for commercial use.

As mentioned above, the hotlet installation distance range is a function of nozzle size, spray flow pressure, coating time, and bottle rotation speed. However, it has been found that it is critical that the relationship of these variables to the bottle separation distance be such that the emulsion stream impinges on the bottles with sufficient force to uniformly coalesce the polymeric coating material. For example, 500 to 1500 bottles
It can be rotated with rp;n. Since the gel was completely formed on the bottle by gradually increasing the weight of the -C membrane rupture under the conditions shown in the above experimental example, it was found that the coating restricted the dispersion flow around the bottle. This is because the gel layer acts as a cushion against further gel formation.
It is shown that a stabilizing dispersion layer is formed on top of it.

Good results have also been obtained by applying the emulsion method to the arched bottle surface at right angles rather than tangentially.

EXAMPLE To further illustrate the principles of the invention, a vinylidene chloride lower alkyl acrylate and acrylonitrile latex (Uniono P4 Ro-153) was coated using the apparatus shown in FIG. The specific gravity of the latex was 1190, and the proportion of solids was about 40%. The main polymer content of the copolymer was qualitatively confirmed by infrared spectroscopy, and the monomer proportions were the same as the representative amounts listed above. Using the airless nozzle device shown in Figure 1, 12 Pl
U'1゛I published it in Hottle. Nozzle pressure 650psi
g for 200 milliseconds at a rotational speed of 60 orpm, blowing approximately perpendicular to the arched bottle surface (= J ke). Under the conditions of this experiment, the coating weight of the 12 bottles was approximately 400p to 470mg. A 400 milligram coating would be approximately 8 microns thick as described above. After coating, the wet coating was dried by passing it over a radiant heat plate for about 15 minutes with a surface temperature of about 60 (10 F), leaving about 9 CnL (
The bottle was horizontally rotated about a horizontal axis at a speed of 10 to 6 Orpm at points approximately 35 inches apart.

Approximately 7.621 and 10.16 cu above the plate surface
(6 inches and 4 inches) points are about 70tC (158°F) and about 65C, respectively.
(149°F) of heat.

Bottles coated under these conditions were rated 10, which indicates that these bottles form a uniformly clear coating with the characteristics and high quality exhibited by bottles meeting the specifications in Figure 4. It qualitatively indicates that it has commercial value. A thin polymer gel film was coated on the interface between the broken membrane and the bottle. As the gel layer structure develops outward from the bottle surface, a layer of dispersed polymer particles forms on top. The appearance of the wet bottle at this stage is identical to the wet bottle shown in Figure 2, approximately 75 seconds after coating. Barrier coatings with uniform clarity upon controlled drying with radiant heat were superior because the thin gel layer performed the essential function of uniformly adhering the dispersant to the wet coating. The outer surface of the polyethylene terephthalate hole is smooth, homogeneous, and uniform. ! A polymeric coating was formed having a temperature of 74°C with virtually no cracks or cracks, but the coating was 9°C in 16 weeks at 26°C at an internal bottle pressure of 60 psig.
It has an air-tightness that ensures that less than psig is lost.

EXAMPLE Another group of bottles was treated in the same manner as in Example H. However, in this case, the relative humidity is approximately 71℃ (16
It was dried in an oven for about 6 minutes at a temperature of 0° ■ Pa). Comparing the bottles of Experimental Examples ① and ①, it was found that the longest shelf life was obtained with the radiation heating method, which dries in a relatively short time compared to convection heating. Therefore, the radiant heating l& is
This is a preferred method for completely breaking down the gelation of a wet film by 1°, resulting in a barrier rupture having uniform transparency.

EXAMPLE To further illustrate the principles of the invention, a latex of vinylidene chloride, aluminum acrylate and acrylonitrile (Morton Self-Environment 20+1) was impact coated using the apparatus shown in FIG. The latex had a specific gravity of t 195 and contained approximately 40% solids. The main chemical macromolecular composition of the copolymer was qualitatively confirmed by infrared spectroscopy, and the proportion of monomers is similar to the representative amounts mentioned above. Using the airless nozzle apparatus shown in FIG. 1, twelve PET bottles were sprayed approximately 2.5 inches from the nozzle. Nozzle pressure 650
The coating weight of the 12 bottles was approximately 400 to 470 milligrams. The coating is about 8 microns thick, like that of chives.

After application, the wet coating was dried for approximately 15 minutes over a radiant heat plate having a surface temperature of approximately 6000F, approximately q cm on the side of the plate.
The bottle was horizontally rotated about the horizontal axis at a point (3.5 inches) with a rotational speed of 10-60 rp+n.

Approximately 7.62 Cnl and io, i6 on the plate surface
Thermocouples placed 3 inches and 4 inches apart give out heat of about 70p (158°F) and about 65C (149°F), respectively. The bottles coated under these conditions were rated at 1G, which indicates that these bottles had a uniformly transparent coating with the characteristics and high quality exhibited by bottles meeting the specifications in Figure 4. A coating treatment was carried out to form a polymer gel thin film at the interface between the film and the bottle, which qualitatively indicates that the product has commercial value. As the gel j4 structure develops outward from the bottle surface, a layer of remaining dispersed polymeric particles forms on top. The appearance of the wet bottle at this stage is the same as the wet bottle shown in Figure 2 about 15 seconds after painting. Because the thin gel layer performed its essential function of uniformly adhering the dispersant to the wet coating, a barrier coating of uniform transparency was obtained upon controlled drying with radiant heat. A polyethylene terephthalate bottle similar to that in Experimental Example (2) was obtained.

A group of bottles in each example was treated in the same manner as in Experimental Example ■, except that in this case, the relative humidity was 1% and the temperature was approximately 54.3 C~6.
Dry in oven convection heat at 81 C (1300F-1550F) for 3 minutes.

A comparison of the bottles obtained in Experimental Examples 1 and V shows that heating with radiant heat for a relatively short period of time provides the longest shelf life. Therefore, radiant heating is the preferred method to completely gel and collapse the wet film into a uniformly transparent i<rear coating.

Although the present invention has been described in detail above, it should be understood that the present invention is not limited to the specific embodiments described above, and may be modified in various ways without departing from the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is an experimental setup showing I) JD T-bottle coating according to the present invention. Figure 2 shows 1) E T before drying, 15 seconds after coating.
12 is a view similar to FIG. 11 but without the bottle; FIG. FIG. 6 is a view similar to FIGS. 1 and 2 showing the coating on the ET bottle separated from the spray nozzle. FIG. 4 is a diagram showing the difference in appearance between a bottle coated by the method shown in FIGS. 1 and 2 and a bottle coated by the method shown in FIG. 6. and FIG, 2 FIG, 3 FIG, 4 FIG, 5 Time (seconds) Appearance: 1--1 +2-Publication-3-14 To1 Procedural Amendment August 60, 1981 By Mr. Kazuo Wakasugi, Commissioner of the Patent Office Covering method and device 3, relationship with the case of the person making the amendment Patent applicant 4, agent 5 Subject of amendment ``Description'' (1) As shown in the attached sheet, we will submit one printable full-text specification. . Report: At the time of application, I submitted a handwritten statement, but I will now replace it with a typed statement. Procedural amendment (method) % formula % method and device 3, relationship with the person making the amendment Patent applicant name Nordson Corporation (name) 48 Agent (1) 1st to 4th clearly drawn as shown in the attached sheet We will submit one copy of Figure 5 with the figures and explanatory text removed.

Claims (1)

[Claims] 1. A method of coating a substrate with a homogeneous polymer film, comprising:
1. Installing a substrate with a surface to be coated. a step of bombarding the surface with an aqueous stabilizing polymer dispersion flow; a step of initially forming on the surface a gel-covering layer that is adhered to the surface and obtained by destabilizing the dispersion flow upon impact; A monolithic wet coating comprising a polymer dispersion coating layer that completely covers said gel layer and is adhered to the substrate via said gel layer, which serves as an interfacial layer, by continuous exposure of said coating layer to a stabilizing polymer dispersion stream. heating the integral liquid film to form a substantially completely gelled coating over its entire thickness on the substrate; and further heating the gelled coating to , coalescing the polymer into a substantially homogeneous coating over a substrate. 2. A method according to claim 1, characterized in that the substrate is a preformed plastic. 2. The method of claim 2, wherein the preformed plastic is polyethylene terephthalate and the stabilizing dispersion polymer is a vinylidene chloride copolymer. 4. The method according to claim 6, wherein the copolymer contains a copolymerizable acid monomer selected from the group consisting of low alkyl acrylate, acrylonitrile and acrylic acid, and mixtures thereof. 5. The method of claim 1, wherein the substrate is a preformed plastic container. 6. The method of claim 5, wherein the preformed plastic container is comprised of polyethylene terephthalate, and the stabilizing dispersion polymer is a vinylidene chloride copolymer. . 7. A method according to claim 5, characterized in that the plastic container has an arched outer surface and that the dispersed flow impinges at an angle substantially perpendicular to the front (■). 8. The method according to claim 1, characterized in that the bottle is rotated during the impact formation of the one-body heat coating. 9. The method according to claim 1, 10. A method according to claim 9, characterized in that heating is performed by radiant heating means to form a substantially completely gelled coating.
A method comprising applying the one-body temperature coating at a thickness of about 4 to 24 microns. 11. A method according to claim 10, characterized in that the one-thermal coating is allowed to dry for about 1 to 2 minutes. 12. The method according to claim 9, characterized in that the bottle is rotated about a horizontal axis while being held over the radiant heating means. 10. A method according to claim 1, characterized in that the dispersed stream is impinged on the surface by means of an airless spray nozzle. 14. The method of claim 13, wherein the nozzle directs the dispersed stream at an angle substantially perpendicular to the substrate surface. 15. The method of claim 16, wherein the substrate is a plastic bottle and the nozzle delivers a stream of vinyl chloride copolymer. 16. The method of claim 15, wherein the substrate is polyethylene terephthalate and the vinylidene chloride copolymer contains at least one acrylic or methacrylated monomer. How to characterize it. 1Z The method of claim 16, wherein the copolymer consists primarily of 99 to 70 weight percent vinylidene chloride and 1 to 40 weight percent of at least one acrylic or methacrylated monomer, and , 1o of the total amount of the two monomers. A process characterized in that it contains, per part by weight, at least a portion of up to ioo parts by weight selected from other ethylenically unsaturated monomers. 18 In the method according to claim 1,
A method characterized in that the one-body temperature coating is applied to a thickness of about 4 to 24 microns. 19 In the method according to claim 1,
A method characterized in that the coating is dried by heating with hot air in an atmosphere having a relative humidity of 20 to 90%. 20. A method for coating a substrate with a homogeneous polymeric coating, comprising: installing a polyethylene terephthalate container having an arch-shaped coating surface; bombarding said surface with a stabilized dispersion stream of vinylidene chloride copolymer; initial formation on the surface of a gel layer of the polymer coating that is adhered to the surface and that results from destabilization of the dispersant upon impact; continuing to expose the gelled coating layer to a stabilizing polymer dispersion stream; forming a monolithic wet coating comprising a polymer dispersion coating layer that completely covers the gel layer and is adhered to the substrate via the gel layer, which acts as an interfacial layer; heating the one-body temperature coating; forming a substantially completely gelled coating over its entire thickness on the surface, and further heating the gelled coating to coalesce the polymer into a substantially homogeneous coating covering the substrate; A method characterized by comprising the steps of: 21. The method of claim 20, wherein the coating is applied to a thickness of about 25 to 12 microns. 2. The method according to claim 20, characterized in that heating is performed by radiant heat means. 26. A method according to claim 2o, characterized in that the container is continuously rotated while being impinged by the flow from an airless spray nozzle. 24. A method according to claim 26, characterized in that the container is rotated and the flow impinges on the surface at an angle substantially perpendicular to the surface. 25. A method of coating a substrate with a homogeneous polymeric coating, comprising: placing a bottle with an arched external surface, stabilizing the vinylidene chloride copolymer at an angle substantially perpendicular to said surface; a step of initially forming a gel coating layer on the bottle surface that is adhered to the bottle surface and obtained by destabilization of the dispersant upon collision; then, continuing the gel coating layer and applying the gel coating layer to the bottle surface; forming a monolithic wet film comprising a polymeric coating layer that completely covers the gel layer and is adhered to the bottle via the gel layer as an interfacial layer upon exposure to a stabilizing polymer dispersion; heating the one-body temperature coating with radiant heating means to form a substantially completely gelled coating over the entire thickness of the surface; and further heating the gelled coating; A method comprising the steps of: coalescing the polymer into a substantially homogeneous coating covering the bottle. 26. A method according to claim 25, characterized in that the series of bottles is moved in succession at a rate of 600 bottles per second or more. 2Z The method according to claim 25, characterized in that the bottle is heated with radiant heat while being rotated on one side. 28. A method according to claim 25, characterized in that the bottle is continuously rotated to impinge on the flow and heated. 2′? , providing a substrate having a surface to be coated;
Impacting the surface with an aqueous stabilizing polymer dispersion stream to initially form a gel coating layer that is adhered to the surface and obtained by destabilization of the dispersion stream upon impact, and then continuing the gel coating layer. to form an integral wet film comprising a polymer dispersion coating layer that completely covers the gel layer and is adhered to the substrate through the gel layer as an interfacial layer; Heating the integral coating to form a substantially completely gelled coating over the entire thickness on the substrate, and further heating the coating causes the polymer to coalesce and substantially cover the substrate. A plastic substrate having a smooth, homogeneous, and uniformly transparent vinylidene chloride copolymer gas barrier coating formed by a coating method that forms a homogeneous coating. 30. In the substrate according to claim 29,
A substrate characterized in that it is made of plastic polyethylene terephthalate. 31. A bottle having an arched outer surface is provided, and a stabilized dispersion stream of vinylidene chloride copolymer is impinged on the bottle at an angle substantially perpendicular to the surface, and the bottle is adhered to the surface of the bottle.
A gel coating layer obtained by destabilization of the dispersant upon collision is initially formed on the surface, and then the gel layer is completely formed by exposing the gelled coating layer to the stabilizing polymer dispersion flow. forming an integral wet film comprising a polymer coating layer adhered to the bottle via the gel layer serving as an interfacial layer; Forms a thick, substantially completely gelled coating. and a coating method in which the gelled coating is further heated to coalesce the polymer into a substantially homogeneous coating covering the bottle, and at 60 psi.
g bottle internal pressure is 1 at a temperature of 23 G and a relative humidity of 50%.
Polyethylene having a smooth, homogeneous, uniformly transparent, substantially crazed or non-cracking coating on its exterior surface with gas barrier properties that provide a loss of 9 psig or less over a period of 6 weeks. Terephthalatehotol. 62. An apparatus for coating a substrate with a polymeric coating, comprising spray nozzle means for dispensing an aqueous polymer stabilized dispersion stream, means for actuating said nozzle means to dispense said stream, and upon actuation of said nozzle means said The flow impinges on the substrate surface to initially form a gel coating layer that adheres to said surface and is obtained by unstabilization of said dispersant upon impact;
Continued operation of the spray nozzle means exposes the gel coating layer to the stabilizing polymer dispersion stream, thereby completely covering the gel layer and adhering the polymer dispersion coating layer to the substrate via the gel layer, which serves as an interfacial layer. means for positioning a substrate proximate a nozzle means to form an integral wet coating comprising: and heating said one-body temperature coating to form a substantially completely gelled coating and coalescing said polymer. Apparatus comprising means for forming a substantially homogeneous coating over a substrate. 66. The apparatus according to claim 62, further comprising means for rotating said base body upon actuation of said nozzle means. 34. The device according to claim 62, characterized in that the nozzle means is a hydraulic nozzle A means. 55. Apparatus for coating a polyethylene terephthalate substrate with a polymer coating, comprising spray nozzle means for dispensing a stream of vinylidene chloride copolymer; means for actuating said nozzle means, said stream impinging on said substrate surface upon actuation of said nozzle means and adhering to said surface, resulting in a gel coating resulting from destabilization of said dispersant upon force/impingement; The layer is initially formed and then exposed to a stream of the stabilized polymer dispersion by continuous operation of the nozzle means to completely cover the gel layer and to form the gel layer which will become an interfacial layer. means for positioning the substrate proximate the nozzle means to form an integral wet coating comprising a polymer-dispersed coating layer adhered to the substrate through the nozzle means, and heating the one-body temperature coating to substantially completely gelatinize the coating. and means for coalescing said polymer into a substantially homogeneous coating over a substrate. 36. The apparatus according to claim 65, further comprising means for rotating said substrate upon actuation of the nozzle means. 37. The device according to claim 35, characterized in that the nozzle means is a hydraulic nozzle means. 38 Polyethylene terephthalate bottles were continuously coated with vinylidene chloride copolymer so that the internal pressure of the 6 Q psig bottle was lost no more than 9 psig ”i over a 16 week period at a temperature of 23C and 53% relative humidity. Apparatus δ for forming a polymer coating on the outer surface of a bottle that is smooth, homogeneous, has uniform transparency, and is substantially free from cracks, cracks, and small cracks.
an enclosure for receiving a series of continuously moving bottles to be coated and open at both ends to allow entry and exit of the bottles, disposed within the enclosure and containing vinylidene chloride copolymer a spray nozzle means for dispensing the flow; when the nozzle means is actuated, the flow collides with the bottle surface and is adhered to the surface, and initially forms a Kel coating layer that cannot be obtained due to destabilization of the dispersant at the time of collision; Thereafter, the nozzle means is continuously operated, and the gel coating layer C is exposed to the stabilizing polymer dispersion flow to completely cover the gel layer and adhere to the bottle via the gel layer which becomes an interfacial layer. sequentially transporting the bottle into and out of the enclosure to form an integral wet coating comprising a polymer dispersion coating layer;
Apparatus characterized in that it comprises conveying means for accessing said nozzle means and radiant heating means for drying the coating on the bottle to a substantially tacky state so that the bottle does not become distorted. 69. The apparatus of claim 38, further comprising means for rotating the bottle within the enclosure relative to the heating means. 40. The apparatus of claim 58, further comprising means for collecting overspray within said enclosure and returning it to the nozzle means. 41. The device according to claim 68, characterized in that the enclosure is provided with relative humidity adjusting means. 42. In the device according to claim 40,
An apparatus characterized in that the means described above can achieve a material transport efficiency of about 95% W. 46. Apparatus according to claim 38, characterized in that the nozzle means is a hydraulic nozzle means.