WO2007060660A1

WO2007060660A1 - Homopolymer pvc resin formulation

Info

Publication number: WO2007060660A1
Application number: PCT/IL2006/001346
Authority: WO
Inventors: Moshe Lipper; Eyal Edry
Original assignee: E.M.A.T Ltd
Priority date: 2005-11-22
Filing date: 2006-11-22
Publication date: 2007-05-31

Abstract

The invention relates to a PVC formulation and uses thereof in the preparation of PVC-based sheets and packaging enclosures. The invention additionally relates to PVC-based multilayer sheet assemblies having barrier qualities, preventing penetration of, e.g. humidity, UV rays and solid particulates of any size.

Description

HOMOPOLYMER PVC RESIN FORMULATION

FIELD OF THE INVENTION

This invention relates to a multipurpose homopolymer PVC (polyvinyl chloride) resin formulation and a method for its manufacture.

BACKGROUND OF THE INVENTION

As a hard plastic, PVC has been used in a great variety of applications and products such as vinyl siding, magnetic stripe cards, window profiles, gramophone records (which is the source of the name for vinyl records), pipe, plumbing and conduit fixtures. It can be made softer and more flexible by the addition of plasticizers, the most widely used being phthalates. In this form, it is used in clothing and upholstery, and to make flexible hoses and tubing, flooring, roofing membranes, and electrical cable insulation.

The dissolving of polyvinyl chloride (PVC) resin in various solvents and the production of uniform PVC solutions (from which the PVC does not precipitate or gel out) has been extensively studied by the PVC industry. Successful dissolution has thus far been achieved by the introduction of various "assisting" plasticizers such as softening agents that allowed complete or partial PVC dissolution.

PCT application number PCT/KR2004/001179 also to the inventors of the present application discloses an improved process for dissolving PVC resin, which comprises adding a plasticizer into an organic solvent followed by the addition of the homopolymer PVC resin. This process results in a transparent PVC solution that may be made into sheets, films and other structures. The use of a softening or dissolving agent such as a phthalate, adipate, phosphate agent or a combination thereof was needed in order to achieve a highly transparent and non-gellous PVC solution. US Patent No. 4,529,768 to Achard et al, discloses a homogenous solution based on PVC which can be shaped and a process for its preparation. The solution is prepared, in line with the exemplified processes, at high temperatures necessary for the dissolution of the PVC. The resulting PVC solutions, while being homogenous, are highly viscous (having viscosity between 15 and 2,000 poises). Japanese Patent Application number 60-15433 discloses a process for the manufacture of a PVC composition which comprises dissolving waste PVC in THF in the presence of plasticizers such as a phthalate.

Numerous other publications have reported the use of solvents such as THF for the dissolving of PVC or PVC waste and the production of PVC solutions of low transparency and high viscosity. All of these solutions have employed in the process at least one plasticizer. The dissolution of a PVC resin in an organic solvent, in the absence of a plasticizer was not disclosed or suggested.

SUMMARY OF THE INVENTION It has now been surprisingly found by the inventors of the present invention that a solution comprising only homopolymer PVC (polyvinyl chloride) resin in an organic solvent such as ketone or ester solvent or a solvent mixture comprising thereof may be prepared and used for various purposes without necessitating the use of any one or more plasticizer, e.g., softening or dissolving agents such as those used in the art or in the invention disclosed in PCT/KR2004/001179.

The primer formulation of the present invention comprises pure homopolymer PVC resin and a ketone solvent, with no other active components. This formulation, as will be described, was found to have the following characteristics: 1. it is stable at room temperature, 2. it is transparent, non-gellous in nature,

3. it has a viscosity at a narrow range of between 5 and 50 poises,

4. it comprises at least 5% dissolved PVC resin,

5. it may be applied onto a great variety of surfaces based on the specific application, 6. it may be used as a basic formulation for many applications and may be treated with a great variety of additives, all of which not being stabilizers or softeners, to impart thereto a desired physical characteristic or a plurality of such characteristics.

Thus, in a first aspect of the present invention, there is provided a formulation consisting a pure homopolymer PVC (polyvinyl chloride) resin and at least one ketone solvent. This formulation preferably consists PVC in an amount raging from 5 and 40% of total weight of the formulation. In one embodiment of the invention, the primer formulation consists between 5 and 20% PVC resin, preferably between 5 and 15% PVC resin and more preferably between 5 and 12% PVC resin.

In another embodiment, the primer formulation has a viscosity between 5 and 50 poises. In another embodiment, the formulation exhibits pseudo-plastic properties, namely exhibits a reduction in the solution viscosity with an increase in the shear rate. In another embodiment, the primer formulation is transparent.

Herein, the expressions "homopolymer PVC (polyvinyl chloride) resin", homopolymer PVC resin", "PVC resin", "resin" or any lingual variation thereof are used interchangeably and unless otherwise specifically stated, refer to a resin of PVC homopolymer composed of identical monomeric units, each such unit being vinylchloride. The homopolymer PVC resin used in the method of the invention is commercially available and may also be prepared in accordance with known organic synthetic methods. Its properties may vary depending on the polymerization method and temperature employed during synthesis. Typically, the higher the polymerization temperature, the lower the molecular weight of the homopolymer PVC resin produced.

The homopolymer PVC resin may be of any molecular weight.

The term "pure homopolymer resin" refers to a commercially available or synthesized homopolymer PVC resin being substantially free of any major impurities, such as additives or contaminants. Thus, pure excludes recyclable or waste PVC material or any additive which is not by definition a homopolymer PVC resin.

Typical PVC resins, and among them homopolymer PVC resin, have an average molecular weight in the range of about 20,000 to about 100,000 Daltons and a Fikentscher K- value ranging from about 41 to about 98. Certain PVC resins show optimum physical properties and process performance for particular applications. Depending on the polymerization method and manufacturing conditions, the PVC resin may vary in resin particle size and porosity.

In another embodiment of the invention, the homopolymer PVC resin employed has a K- value of between 50 and 58. Despite the fact that the primer formulation of the invention necessitates no plasticizer, e.g., softening or dissolving agents such as those selected from dialkyl phthalates (such as dimethyl, dibutyl, dioctyl, diiso-octyl, didecyl), alcohol derivates of phthalates (such as butyl-benzyl phthalates), trialkyl phosphates (such as tri-(2- ethylhexy)phosphate, tributyl, triaryl phosphates such as triphenyl phosphate), dialkyl adipates (such as dimethyl, dibutyl, dioctyl, didecyl adipate), or dialkyl azelates (such as dioctyl azelate), the primer formulation is stable and may be used in various applications as will be disclosed and exemplified hereinnext. The stability of the formulation may be evident from the following:

(i) its consistency remains substantially unchanged over a period of several years,

(ii) it is stable under various temperatures with no substantial change in the concentration of the dissolved PVC, and (iii) it may be used as "fresh" after prolonged periods of storage.

The primer formulation may be used to coat any surface, as will be exemplified. Preferably, the surfaces are metal surfaces.

The ketone solvent employed in the primer formulation is an organic compound being preferably a liquid at room temperature or a liquid at the temperature at which the dissolution of the PVC resin is carried out, and having at least one ketone functional group. A ketone functional group, as known to a person skilled in the art is a carbonyl

(C=O) group substituted by two independent carbon groups. A person skilled in the art will be able to determine a suitable ketone solvent for a specific use or application without undue experimentation based on parameters such as viscosity of the final solution, the temperature at which the dissolution is carried out, the volatility of the solvent, etc.

The ketone solvents may be linear, branched, cyclic, macrocyclic, complexed, or additionally substituted organic compounds, having each at least one ketone group. Non-limiting examples of such ketone solvents are dimethyl ketone (acetone), methylethyl ketone (MEK), diethyl ketone (DEK), and methyl-zso-butyl ketone (MIBK). The term "ketone formulation" refers to a formulation based on the at least one ketone solvent as defined hereinabove.

The primer formulation of the invention may comprise either a single ketone solvent or any combination of ketone solvents, at any ratio. For example, the formulation may comprise MEK and MIBK at any such ratio as 1:100, 1 :2, 1:1, 1:0.5,

1 : 0.01 and the like. In cases where two or more ketone solvents are employed, they may be added together or sequentially into the reaction mixture in order to impart the solution the desired physical attributes needed for the dissolution of the PVC resin or for the specific target application.

In yet another aspect of the present invention, there is provided a method for the manufacture of the primer formulation of the present invention, said method comprising adding into at least one ketone solvent an amount of a homopolymer PVC resin and mixing the mixture until a transparent solution is obtained.

The mixing of the initial mixture may last as long as it is needed in order to achieve the desired transparency. Such mixing may be at room temperature or at any other temperature, i.e. higher or lower than room temperature and typically below the boiling point of the solvent or solvent mixture used. The time required to achieve the desired transparency may depend on various factors such as the temperature employed, or the absence of any external temperature, the PVC resin concentration, the rate of mixing, the rate of PVC resin addition into the ketone solvent, and other factors.

Preferably, the dissolution process is carried out in the absence of any applied external heat and is thus said to be carried out at the ambient. Heat evolution, namely an increase in the solution temperature without a corresponding increase in the temperature of the environment and which may be a result of the mixing exothermicity may assist in the dissolution of the PVC resin. However, such heat evolution may not at all be observed. The appropriate amount of the homopolymer PVC resin added into the ketone solvent depends on the concentration of the PVC solution needed. The concentration of the homopolymer PVC resin solution and the amount of homopolymer PVC resin per a specific volume or weight of the solvent may be determined by simple mathematics as would be known to a person skilled in the art. The primer formulation of the invention may be treated with various other additives and solvents (or solutions), none of which being a plasticizer, in order to achieve physical characteristics suitable for a specific application. Such characteristics may be viscosity, concentration, resistance to damage caused by humidity, chemicals, erosive or corrosive atmospheres, heat, marine or acidic atmospheres, physical damage caused by sand, dust, penetrating objects and so on. Such additives may for example be organic or non-organic solvents such as aromatic solvents (e.g., toluene, xylene), antioxidants, biocides, antifoaming agents, antifog additives, viscosity modulators, adhesion promoters, antiblocking agents, antitack agents, slip agents, flame retardant agents, fillers, anti-static agents such as ATMAR 129, copolymers such as Copolymer of PVC, homopolymers, metal powders such as silver, aluminum and graphite, agents reducing flammability such as antimony oxide, heat stabilizers, UV stabilizers, light blockers, anti-corrosive and anti-erosive agents, glass fibers, pigments, and others. In all embodiments, the additive is not a plasticizer such as a softening or dissolving agent.

Thus, in a further aspect of the present invention, there is provided a formulation comprising pure homopolymer PVC (polyvinyl chloride) resin, at least one ketone solvent and at least one additive as disclosed hereinabove. In another aspect, there is provided a formulation comprising a pure homopolymer PVC (polyvinyl chloride) resin and at least one ketone solvent, provided that said formulation does not comprise one or more plasticizers, e.g., softening or dissolving agents.

In one embodiment of this aspect, said one or more plasticizer is selected from dialkyl phthalates, alcohol derivates of phthalates, trialkyl phosphates, dialkyl adipates, and dialkyl azelates.

In another embodiment of this aspect, the formulation further comprises at least one additive as disclosed hereinabove.

In still another aspect of the invention, there is provided a formulation comprising pure homopolymer PVC (polyvinyl chloride) resin, at least one ketone solvent and at least one additive as disclosed hereinabove, provided that said at least one additive is not a plasticizer.

In some embodiments, the ketone formulation comprises at least one additional solvent selected from aromatic (e.g., toluene, xylene, etc) and non-aromatic solvents (e.g., esters, ethers, etc).

The present invention further provides PVC formulations comprising pure homopolymer PVC resin and at least one ester solvent. In some embodiments, the formulation also comprises at least one additive as disclosed hereinabove. In other embodiments, the formulation comprises at least one additional organic solvent such as a ketone solvent.

The ester solvent employed in the formulation of this aspect of the invention is an organic compound being preferably a liquid at room temperature or a liquid at the temperature at which the dissolution of the PVC resin is carried out, and having at least one ester functional group. An ester functional group, as known to a person skilled in the art is a carbonyl (-C(=O)O-) group substituted by two independent carbon groups. A person skilled in the art will be able to determine a suitable ester solvent for a specific use or application without undue experimentation based on parameters such as viscosity of the final solution; the temperature at which the dissolution is carried out, the volatility of the solvent, etc. The ester solvents may be linear, branched, cyclic, macrocyclic, complexed, or additionally substituted organic compounds, having each at least one ester group. Non-limiting examples of such ester solvents are methyl acetate, ethyl acetate, butyl acetate, and cellosolve acetate. The ester formulation of the invention may comprise either a single ester solvent or any combination of ester solvents, at any ratio, or may comprise a combination of at least one ester and at least one ketone solvent.

The formulations of the invention may be applied to or deposited onto various surfaces by different methods such as spraying, brushing, washing, dipping, etc, depending on the application and the thickness of PVC layer required.

Thus, the invention also discloses articles or surfaces made of or coated with the primer formulation of the invention or coated with a formulation which is based on the primer formulation of the invention. Such articles or surfaces which are made of or coated with the PVC resin formulation of the invention may be made of any material such as cement, metal, wood, plastic, alloys, etc. Such surfaces may be floors, walls, appliances, dishes, kitchen appliances, clean room appliances and articles contained therein, sanitary appliances, fabrics, clothing, military appliances and machinery or parts thereof, or any other article or surface.

The invention also discloses, in another aspect, a PVC formulation which comprises or is based on the primer formulation of the invention, or which is manufactured by addition of additives to said primer formulation, but which is absent of any plasticizers or softeners, as detailed hereinbefore.

Non-limiting examples of the formulations of the invention are shown in Tables 1 and 2: %w/w

PVC copolymer and homopolymer 10-30

MIBK 10-35

Cellosolve acetate 10-42

MEK 10-25

Titan dioxide 1-8

Antifoam 0.1-2

UV stabilizer 0.1-2

Heat stabilizer 0.1-2

Dispersant 0.1-2

Table 1: A formulation of the invention suitable for application on concrete walls

%w/w

PVC copolymer and homopolymer 10-30

MIBK 10-25

Cellosolve acetate 10-43

MEK 10-25

Titan dioxide 1-7

Antifoam 0.1-2

Iron oxide 0.1-2

UV stabilizer 0.1-2

Heat stabilizer 0.1-2

Dispersant 0.1-2

Table 2: A formulation of the invention suitable for application on metal surfaces

In another aspect of the invention, there is provided a multilayer sheet assembly.

The multilayer assembly is generally made by coating, one coat at a time, a base film made of a metal foil or a fiber film or sheet or a surface with any one formulation of the invention or any other formulation comprising PVC. The PVC formulation or a formulation based thereon may be applied, e.g., for forming a PVC film to reinforce the base film and endow it with increased resistance to physical and chemical attacks and/or decrease permeability of liquids and gases which would normally penetrate it. The multilayer sheet assemblies of the invention are suitable for installation between structural elements such as joists, rafters, and the like in buildings, thereby affording thermal insulation with a water vapor barrier capability. They may also be used for other insulating applications, such as for instance wrapping and insulating pipes, tanks, etc. The sheet assemblies according to the invention may be vapor barrier assemblies, or they may be thermal insulation products in which such vapor barrier assemblies are used in conjunction with a fibrous thermal insulation layer.

The "base film", as used herein, refers to a film positioned between and in contact with at least two other layers or films, at least one of which preferably being a PVC comprising layer. The expression "a formulation based thereon" refers to a composite PVC formulation that comprises PVC, such as the primer formulation of the invention, and at least one additive. Within the context of this aspect of the invention, the additive may be any additive known to a person skilled in the art.

Non-limiting examples of such additives are: antioxidants, biocides, antifoaming agents, antifog additives, viscosity modulators, adhesion promoters, antiblocking agents, antitack agents, slip agents, flame retardant agents, fillers, anti-static agents such as ATMAR 129, copolymers such as Copolymer of PVC, homopolymers, metal powders such as silver, aluminum and graphite, agents reducing flamniability such as antimony oxide, heat stabilizers, UV stabilizers, light blockers, anti-corrosive and anti- erosive agents, glass fibers, pigments, plasticizers and others.

Non-limiting examples of such composite PVC formulations are shown in Tables 3 to 8:

%w/w

PVC copolymer and homopolymer 10-30

MIBK 15-35

Cellosolve acetate 25-40

MEK 5-15

Flame retardant 1-4

Phthalate plasticizer 1-4

Phosphate plasticizer 2-4

Antifoam 0.1-3

UV stabilizer 0.1-2

Heat stabilizer 0.1-2 Antioxidant 1-3

Dispersant 0.1-3

Table 3: Wood coating (transparent coating)

%w/w

PVC copolymer and homopolymer 10-20

MIBK 15-35

Cellosolve acetate 25-40

MEK 5-15

Flame retardant 1-4

Phthalate plasticizer 1-5

Phosphate plasticizer 1-4

Titan dioxide 0.1-2

Antimony trioxide 2-5

Antifoam 0.1-3

UV stabilizer 0.1-2

Heat stabilizer 0.1-2

Antioxidant 0.1-4

Dispersant 0.1-3

Table 4: Wood white coating

%w/w

PVC copolymer and homopolymer 10-25

MIBK 15-35

Toluene 15-25

MEK 10-25

Phthalate plasticizer 5-10

Antifoam 0.1-3

UV stabilizer 0.1-2

Heat stabilizer 0.1-2

Antioxidant 0.1-3

Table 5: Peelable coating. %w/w

PVC copolymer and homopolymer 10-35

MIBK 20-40

Cellosolve acetate 10-25

MEK 10-25

Flame retardant 1-4

Phthalate plasticizer 2-7

Phosphate plasticizer 1-5

Titan dioxide 1-4

Antimony trioxide 2-7

Black pigment 0.1-3

Antifoam 0.1-3

UV stabilizer 0.1-3

Heat stabilizer 0.1-3

Dispersant 0.1-3

Antistatic agent 0.1-3

Table 6: Flexible applications

%w/w

PVC copolymer and homopolymer 10-30

MIBK 10-35

Cellosolve acetate 10-42

MEK 10-25

Phthalate plasticizer 1-7

Titan dioxide 1-8

Antifoam 0.1-2

UV stabilizer 0.1-2

Heat stabilizer 0.1-2

Dispersant 0.1-2

Table 7: Concrete wall coating

%w/w PVC copolymer and homopolymer 10-30 MIBK 10-25

Cellosolve acetate 10-43

MEK 10-25

Phthalate plasticizer 1-6

Titan dioxide 1-7

Antifoam 0.1-2

Iron oxide 0.1-2

UV stabilizer 0.1-2

Heat stabilizer 0.1-2

Dispersant 0.1-2 Table 8: Metal surface coating

The manufacture of the multilayer sheet assembly may begin from the center of the sheet outwards, with the application of a suitable PVC formulation on one face of a base film, e.g. aluminum sheet, or on both of its faces. Alternatively, the base film may be coated with a primer formulation on one of its faces while the other may be coated with a different formulation comprising, for example, a flame-retardant agent. This affords a base film sandwiched between and in contact with a PVC layers on one face and a composite PVC layer containing a flame retardant agent on the other. The coated base film may next be treated with one or more additional coats of the PVC formulation or a formulation based thereon, thus forming a multilayered sheet assembly. In some embodiments, the first layer of PVC, on either face of the base film, may be coated with a layer of a formulation not containing PVC, e.g. an adhesive material or a fibrous sheet, as may be decided by the manufacturer and required of the final product.

The multilayered sheet assembly may also be manufacture in the order of the layers, namely from top to bottom or from one face to the other. In some embodiments, the manufacturing of the multilayer sheet may begin by applying a coat of a composite PVC formulation or another formulation to a surface, e.g., glass, Teflon, from which it may be peeled off. In such an example, the layer applied to the surface would be the exterior film or seal layer of the multilayer sheet. Once applied to the surface, the other layers are applied sequentially in order. After all layers have been formed, the multilayered sheet may be peeled off from said surface to afford the desired multilayer assembly.

Thus, the invention further provides a PVC-based multilayer sheet or film having at least one base film and at least one layer of PVC. In one embodiment, said at least one layer of PVC is a layer of the PVC primer formulation of the invention. In another embodiment, said at least one layer of PVC is a layer of composite PVC comprising PVC and at least one additive as disclosed herein.

In some embodiment, said at least one layer of PVC is coated on said at least one base film by treating said base film with a PVC formulation, which may or may not comprise any additive.

In other embodiment, the base film is coated with a single coat of PVC on each of its faces, thus affording a three-layer sheet assembly having a middle base film and two outer layers each of the same or different PVC composite. The coating of each layer is typically achieved by, for example, brushing, or spraying as may be required and/or as may be possible based on the consistency and viscosity of the formulation and based on the desired thickness of each of the layers.

In another embodiment, the multilayer sheet assembly may be further treated with a coat of a primer formulation comprising an adhesive in order to promote the adhesion of that layer to another surface, such as cement, wood, metal, plastic, etc. Preferably, the adhesive layers are positioned between two layers of the sheet to maintain the two layers in position relative to each other and prevent undesirable delamination.

In some embodiments a peelable adhesive layer may be used, which is designed to have neither cohesive failure nor delamination from one or both adjacent layers upon application of a suitable manual force to provide, e.g., an opening feature or for the lamination of a new peelable layer. Unless otherwise indicated, an adhesive layer may be based on PVC or can have any suitable composition that provides a desired level of adhesion with the one or more surfaces in contact with the adhesive layer material.

Preferably, an adhesive layer placed between a first layer and a second layer in a multilayer sheet may comprise components of both the first layer and the second layer to promote simultaneous adhesion of the adhesive layer to both the first layer and the second layer to opposite sides of the adhesive layer.

Thus, the multilayer sheet of the present invention may be a laminate. The adhesive layer may also be used as an exterior layer of a rrmltilayered or single-layer sheet and be used to laminate exterior surfaces such as walls, wood surfaces, metallic surfaces, plastic surfaces, cement surfaces, other PVC surfaces, alloy surfaces, polymeric surfaces, glass surfaces and others, of appliances, buildings, construction and industrial machinery, clean rooms, medical appliances and equipment, etc. In such embodiments, the adhesive layer is in contact with, e.g. a wall surface, and the other face of the multilayer sheet or single layer sheet may act as a seal layer to provide the sealing of the sheet or the surface to which it is attached.

As used herein, the "seal layer" is the exterior layer which is involved in the sealing of the inner layers or base film to itself; to another layer of the same sheet or another sheet; and/or to another article to which it is attached e.g. a wall surface. In general, the sealant layer is an exterior or an interior layer of any suitable thickness that provides for the sealing of the base layer to itself or another layer.

The multilayer assemblies may have 2, 3, 4, 5, 6, 7, 8, 9, 10 or more layers, of varying thickness, compositions and chemical and/or physical characteristics. AU layers are substantially coextensive.

Thus, in another embodiment, there is provided a multilayer sheet assembly comprising:

1. at least one base layer; 2. at least one layer of PVC; and

3. optionally, at least one layer of composite PVC containing at least one additive.

The multilayer sheet assembly may further comprise at least one layer of a reinforcing material. In another embodiment, the multilayer sheet assembly is a six-layer sheet comprising:

1. at least one first layer of PVC;

2. at least one first layer of composite PVC containing at least one additive; 3. at least one base layer; and

4. optionally at least one layer of reinforcing material.

In another embodiment, the six-layer sheet comprises a first layer of PVC; a first layer of composite PVC containing at least one additive; a layer of metallic material, e.g. metal sheet or foil; a second layer of composite PVC containing at least one additive; a layer of reinforcing material; and a second layer of PVC.

In still another embodiment, the first layer of composite PVC containing at least one additive is on top of said first layer of PVC; said layer of metallic material is on top of said first layer of composite PVC containing at least one additive; said second layer of composite PVC containing at least one additive is on top of said layer of metallic material; said layer of reinforcing material is on top of said second layer of composite PVC containing at least one additive; and said second layer of PVC is on top of said layer of reinforcing material. AU layers are essentially coextensive.

In another embodiment, the at least one additive is selected from heat and UV stabilizers, light blocker, pigments, fillers, flame retardants, anti-static agent, anti- corrosive agent, anti-erosive, modulator of chemical adhesiveness, homopolymers or copolymers, metal powders or solutions, salts, plasticizers, softening agents, dissolving agents, stabilizers or any combination thereof. Preferably, said at least one additive is vinyl acetate.

In some embodiments, the base film is a metal foil of any metal or alloy. The metal foil is preferably an aluminum foil. In other embodiments, the base film is a net made of any material, e.g., plastic, polymers, metal, glass, etc. In some other embodiments, the base film is a fibrous sheet made of any type of fiber, e.g. aggregations of fibers not connected to one another, felts, unwoven or woven fabrics, vegetable fiber, jute and the like.

In another embodiment, the multilayer assembly has at least six layers, preferably between 6 and 13, more preferably between 6 and 11 and most preferably at most 10 layers.

It should be understood that the description and examples provided herein relate to multilayer sheet assemblies without indication as to their length or width, their final color, and/or shape. Such dimensions and other parameters are not critical to this invention, and the sheet assemblies may be of essentially any convenient shape or size. Typically, multilayer assemblies according to the invention can be made, shaped, colored and/or cut as may be required.

According to another embodiment, the multilayered sheet is used as a packaging material for bags, sleeves and other packaging enclosures. Such packaging enclosures may be prepared by overlapping several of the aforementioned multilayer sheets at their edges and subsequently bonding said sheets together by e.g. a PVC homopolymer formulation, as described in the Examples.

The sheet assemblies and packaging enclosures of the invention constitute barriers for water, UV, corrosive and/or erosive materials, fire and other agents which can cause the deterioration of the enclosed object which said sheet or packaging enclosure is set to protect, thus preserving the packaged object dried and potentially extending its storage life.

Preferably, an efficient sealed packaging is obtained by introducing nitrogen gas, via inlet tubing, into the package, vacuuming the package interior through an outlet tubing, and sealing the openings with PVC homopolymer formulation while removing the tubing.

The said film, sheet and packaging enclosure constitute a barrier for water and UV, thus preserving the packed items dried and unchanged with time.

BRIEF DISCRIPTION OF THE FIGURES

In order to understand the invention and to see how it may be carried out in practice, numerous examples are provided and should be considered as non-limiting of the invention as disclosed. In the figures:

Fig. 1 shows a cross sectional schematic of a first exemplary multilayer film. Fig. 2 shows a cross sectional schematic of a second exemplary multilayer film.

Fig. 3 shows a cross sectional schematic of a third exemplary multilayer film.

Fig. 4 shows a cross sectional schematic of a fourth exemplary multilayer film.

Fig. 5 is an illustration of a flow-chart of the process of multilayered sheet production. Figs. 6A and 6B are schematic representations of a packaging steps of a starter, wherein, A is a plan view of the sleeve illustrating the steps of nitrogen introduction, vacuuming and sealing, B is a cross section of the same sleeve, and C illustrates the package after it was sealed in a shrunk form.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In preferred embodiments of the invention, the PVC homopolymer resin is dissolved in a ketone solvent, without any additives, to form a primer formulation which may be used as is, or further formulated by adding other additives, none of which being softening or dissolving agents, to afford PVC based formulations having various chemical and physical characteristics.

The PVC primer formulation or any formulation based thereon, as disclosed herein, may be utilized for example for the manufacture of multilayered sheets having improved capabilities in sustaining high temperatures, high humidity conditions and thus may be used as barriers or packaging enclosures for objects of various sizes and structures. It should be understood, that while the present invention discloses PVC formulations which do not contain any one softening or dissolving agents, as disclosed hereinabove, the multilayer sheet assemblies or enclosures disclosed may comprise one or more layers of PVC with at least one plasticizer.

Referring now to the drawings, Fig. 1 exemplifies a three-layer film structure embodiment of the present invention generally designated with reference numeral 10. This embodiment is directed to a multilayer sheet comprising an outer layer 12 that is an exterior layer comprising a material such as PVC or a composite PVC comprising an additive, and an outer layer 16 that is a sealant layer, each joined to opposite sides of a base film 14 being a metal sheet such as an aluminum foil. The sealant layer 16 comprises for example a composite of PVC and an additive or may be a reinforcing layer made of metal or fiber. The thickness of each of the three layers may vary based on the number of coatings employed and the thickness of the base film.

Referring now to Fig. 2, a cross section of an example of a five-layer sheet assembly is depicted with sheet 20 having an exterior surface layer 22 that is a fire resistant layer joined by a first PVC layer 24 to a base film 26, the other side of base film 26 is joined by a second PVC layer 28 to an exterior layer 30 which is a reinforcing layer. In this embodiment, the base film 26 is a metal sheet, and the exterior layer 30 is a fibrous material made for example of jute.

Referring to Fig. 3, a cross-section of an example of a three-layer PVC film 40 mounted on a surface such as a concrete wall 42 is depicted having an exterior surface layer 44 being a composite of PVC and an acrylic base, in contact with a composite layer of PVC and a softening agent such as DOP 46, and an adhesive layer 48 of PVC and a PVC copolymer and maleic acid, allowing the fixation of the PVC sheet onto the concrete wall. Referring now to Fig. 4, a cross-section of an example of a six-layer film 50 is depicted. Sheet 50 may comprise an exterior layer 52 that is an abuse resistant layer of PVC, which is in direct contact with a first PVC composite layer 54 of PVC and at least one additive and connected to a base film 56. Base film 56 is in direct contact with a second composite layer of PVC 58 and an additive. On the other side of layer 58 there is a reinforcing fibrous layer 60 coated with an exterior layer 62 comprising PVC.

An exemplary PVC formulation was prepared according to the flow chart of Fig. 5. A PVC solution (A) is prepared by first adding dioctyl phthalate (DOP) into methylethyl ketone (MEK), at a constant rate of 1 L/min. Copolymer of PVC and vinyl acetate was added to the above solution at a rate of 2 Kg/min and stirred for 30 minutes, followed by the addition of heat stabilizer and UV absorber. The formed solution was brushed over the surface of both faces of aluminum foil (B) (10-micron thick) and dried completely to form a PVC coated base film (C). A formulation containing PVC homopolymer (D) was sprayed over one face of the resulting assembly, to obtain PVC- coated sheet (E) and further dried for 2 hours. A reinforcing fabric (140 gr/cm²) (F) was placed adjacently to the other face of the assembly affording (G). The PVC primer formulation (H) was next airlessly sprayed over both faces of the sheet and dried to form the desired six-layer sheet (I). The final sheet thickness was about 500 microns.

The foregoing amounts of the components and the other parameter values are given for purposes of example and should not be considered limiting.

A large multilayered sheet (J) may be prepared by juxtaposing several sheets at their edges and by overlapping adjacent sheets by 5 cm. The linkage between sheets may be done by brushing the PVC solution such as the primer formulation over the overlapping areas. The following examples illustrate the invention and are not intended to limit it in any way.

Example 1: Preparation of the Primer Formulation of the Invention

A 200-liter barrel was pre-filled with 60 kg MEK and 37.5 kg acetone. A dissolver positioned in the barrel was turned on and allowed to stir at room temperature at a rate of 700-900 rpm, while 25 kg PVC homopolymer resin having a K value of 57- 59 were poured into the barrel at a rate of 1 kg per minute. As the resin was being added, the rate of the stirring was increased to 1,200-1,400 rpm. After a period of 20 to 30 minutes, the temperature of the solution was measured at between 47° and 50⁰C. No external heat was added. Stirring was continued until a completely transparent solution was obtained.

Transparency and other physical parameters used to determine dissolution of the PVC resin in the ketone solvent(s), may be determined by using any one or more methods known to a person skilled in the art of material science, polymers, surface chemistry and/or other fields.

The primer solution of the invention may be stored at room temperatures for long periods of time (over 24 months) without noticeable deterioration, precipitation or any physical change in the viscosity or any other parameters, and may be used after prolonged storage to prepare the various application formulations disclosed herein.

Example 2: Protective Coating for Wood products

A pre-made solution comprising 15 kg MIBK, 5 kg of a heat retardant such as antimony oxide, 4 kg of a heat stabilizer such as Baerostab UBZ 786 or Baerostab M64, and 4 kg of a UV stabilizer such as Tinovin 81 or Chimassorb 320 was prepared by mixing the ingredients to complete dissolution. This solution was added into the primer formulation of Example 1, while stirring. After completing the addition, 20 kg of a desired dye or microlit were added at a rate of 1 kg per minute while stirring at 1,200- 1,400 rpm.

The resulting PVC formulation was oil free, having a solid content of at least 32% and ready for use as coating for wood products. Application of the formulation onto the wood products was achieved by spraying or brushing and showed no effective dependency on the mode of application. The dry coating was tested under various conditions and was found to comply with Israeli Standard No. 127-11, regarding the following standards which the novel wood coating prepared as disclosed herein was found to comply with:

1. high resistivity to friction, heat and humidity at temperatures as high as

70⁰C; 2. high adhesiveness to wood products;

3. high permeability into the wood;

4. finish stability at dry temperatures as high as 100°C;

5. does not peal under humidity or dryness; and 6. inflammability.

The inflammability of the product was in compliance with US Standard UL-94, Classification V-O for "Test for Flammability of Plastic Material for Parts in Devices and Appliances".

Example 3: Application of wood coating formulation to fiberboards

The formulation prepared and described in Example 2 above was also used to manufacture porous fiberboards having increased stability under extreme conditions such as high humidity, high salt concentration, etching contaminants and chemicals. The coating formulation disclosed in Example 2, as any other formulation of the invention, may be diluted with a 1:1 mixture of MEK and acetone. The degree of dilution may be determined based on the porosity of the fiberboard, its thickness and other physical parameters related thereto.

In a typical application, a fiberboard was placed in the diluted coating formulation for a period of time, depending on the thickness of the fiberboard, allowing penetration of the PVC formulation into a depth of one-third of the board thickness, from each side. After penetration was achieved, the board was taken out, wiped of excess formulation and was dried at 40°C for one hour. Immediately thereafter, the board was allowed to cool at room temperature for a period of about 4 hours. Each fiberboard was next sprayed with the formulation, providing an external coating of 40 microns in thickness, and was allowed to dry.

For the production of multilayered fiberboards, a plurality of such fiberboards was layered one on top of the other in any desirable fashion, pressed from both sides and fixed at temperatures ranging from 134° to 152⁰C, thus allowing a sandwiched fiberboard of the desired thickness and having the characteristics detailed hereinbefore.

Example 4: Coating formulation for cement and concrete structures

Into a primer formulation of the invention, a pre-made solution comprising PVC copolymer and about 2% maleic acid was added at a rate of 1 kg per minute, and the mixture was maintained stirring for about 20 minutes. Thereafter, 6 kg of Talc, and 8 kg of calcium carbonate were added at the same rate while stirring. Next, 8 kg of titan dioxide and 3 kg of a heat stabilizer such as Baerostab UBZ 786 were added and stirring was continued at a rate of 1,200-1,400 rpm for a period of 30 additional minutes, at room temperature.

The resulting formulation was tested and was found to contain at least 28% solids, namely, PVC resin and other additives which have been added, and to have the following characteristics:

1. resistance to erosion (ASTM Gl 54 standard- Standard Practice for Operating Fluorescent Light Apparatus for UV Exposure Nonmetalic Materials);

2. resistance to corrosion as tested in a salt chamber (ASTM B 117 standard- Standard Method of Salt Spray (Fog) Testing); 3. high permeability into porous cement or concrete surfaces;

4. high adhesiveness to external PVC coatings;

5. high adhesiveness to metallic surfaces such as aluminum surfaces.

The formulation was used to coat cement or concrete structures situated in various outdoor locations and exposed to chemical or natural erosive and corrosive conditions.

The application of the formulation to such surfaces involved the following four steps:

Step A: initial treatment of the surface with a 5-10% HCl solution to remove contaminants and dirt from the pores of the surface and allow better penetration of the PVC formulation. Upon washing, the surface was treated with a dilute, fast-drying PVC formulation which was prepared by diluting the formulation of this Example in a 1 : 1 mixture of MEK and Acetone. The purpose of this dilution was to allow better penetration and filling of the pores of the treated surface.

Step B: A formulation as prepared in this Example, to which at least one softening agent such as DOP was added, was applied onto the now-dry PVC covered surface of step A. This DOP-containing formulation was applied onto the first layer in order to increase the already excellent adhesiveness of the next-to-be-applied PVC formulation to the surfaces.

Step C: The top, most exposed layer was made of the primer PVC resin formulation into which an acrylic base resin such as Dagalan 820 was added. Such acrylic resin prevented leakage of the softening agents from the middle layer and provided protection to the surface from outside contaminants, erosion and corrosion elements, UV radiation and other physical damages. - 9? -

Example 5: Application of the coating formulation to manufacture of peelable surfaces

The PVC formulation of the invention was also used as an efficient glue to append metallic surfaces such as aluminum sheets to other surfaces. With the high adhesiveness of the PVC formulations to cement and concrete surfaces, on one hand, and to metallic surfaces, on the other, the use of the PVC formulation as a means to glue such metallic surfaces to cement surfaces was explored.

A cement wall was treated with the PVC formulation of Example 4 as disclosed therein. An aluminum sheet, 1.5 mm in thickness also covered with the formulation on one of its faces (60 micron thick layer of the PVC) was brought into contact with the treated cement wall, and the two were allowed to remain untouched for a period of 24 hours.

The result was an aluminum covered wall which was next treated on its exposed side with a PVC primer formulation and was again allowed to dry. The resulting PVC layer was peeled off without causing damage to the aluminum surface and without causing delamination thereof from the cement wall. Upon peeling, the aluminum surface was re-treated with a new layer of said PVC primer formulation.

It should be understood that the aluminum surface exemplified herein is provided as a non-limiting example only. Other metal sheets may be used. Additionally the metal surfaces may not of any size appliance or object such as metal boxes or containers, of any shape and size.

Applications of such methods may be suitable to clean rooms, laboratories, hospitals and other areas, surfaces or objects which require sterilization. Normal and lengthy sterilization processes may be avoided by using such peelable PVC sheets made of the primer formulation of the invention, as they may be discarded off after peeling from said surface, leaving a sterile surface on which a new layer of the PVC primer formulation may be applied.

Example 6: PVC formulations of various colors

The primer formulation of the invention, or any other formulation based thereon, may be treated with a variety of dyes in order to obtain a colored formulation. For example, to obtain a red or orange colored formulation, iron oxide may be added. Example 7: Manufacture of a Six-Layer Sheet

The six-layer sheet is schematically illustrated in Fig. 4, comprising a base film, a foil, internal primer layers consisting of copolymer PVC/vinyl acetate,_, a reinforcing fabric layer and external layers made of PVC homopolymer resin formulation of the invention.

A flow-chart of the process for the manufacture of a six-layer sheet assembly is shown schematically in Fig. 5 and discussed hereinabove.

A large multilayer sheet is prepared by juxtaposing several films at their edges and by overlapping adjacent films by 5 cm. The linkage between films is done by brushing PVC homopolymer formulation of the invention over the overlapping areas.

A preferred example of packaging of large items, such as a tank starter is schematically shown in Figs. 6A₃ B, C wherein Fig. 6A is a plan view of a sleeve containing a starter 70, which is placed at the center bottom of a sleeve 72. This sleeve is made by connecting the edges of two multilayered sheets, and bonding the sheets with PVC homopolymer resin formulation. This sleeve also contains several inlets with gas tubing 74, 76, 78 and vacuum outlet with tubing 80.

Fig. 6B illustrates a cross-section of the sleeve on plane I of Fig. 6A. Nitrogen gas is introduced into the sleeve through the tubing 74, 76 and/or 78, in order to displace the oxygen, and then the sleeve interior is partially vacuumed through the tubing 80. Finally, all the sleeve openings (including inlets, outlet) are sealed with PVC homopolymer resin formulation of the invention, while removing the tubing.

At this stage, as shown in Fig. 6C, the sealed package 82 is collapsed by the suction, and it is in close contact with the starter body 31, thus forming and hermetically sealed package.

The formed package was refreshed periodically, by cutting open a small window in the package sleeve, checking for any signs of corrosion in the starter, covering the window with a patch of multilayer film, re-introducing nitrogen via inlet tubing, into the package, vacuuming the package interior through an outlet tubing, and finally sealing the whole package with a fresh 50 microns thick layer of PVC copolymer.

The six-layer sheet produced according to this Example had the following properties: The water-vapor penetration rate through the sheet was less than 0.05 gr/m²/day. The resistance to the sheet piercing was 9.3 kg. Tensile strength of the sheet was 104 kg/cm².

Example 8: Preparation of large Al sheets A sheet (10 x 1.6 meter) was manufactured from the above six-layer sheet assembly by juxtaposing ten such sheets and superimposing the edges of the juxtaposed films. These films had a 5-cm width band of overlapping zone. The above sheets were bound together by brushing the above PVC homopolymer resin formulation over the overlapping area. After complete drying, the sheet was ready for packaging applications.

Claims

CLAIMS:

1. A formulation consisting a pure homopolymer PVC (polyvinyl chloride) resin and at least one ketone solvent.

2. The formulation according to claim 1, wherein said PVC is in an amount ranging between about 5 and 40% of total weight of the formulation.

3. The formulation according to claim 2, wherein said PVC is in an amount ranging between 5 and 20% of the total weight of the formulation.

4. The formulation according to claim 2, wherein said PVC is in an amount ranging between 5 and 12% of the total weight of the formulation.

5. The formulation according to claim 1 having a viscosity between 5 and 50 poises.

6. The formulation according to claim 1 being transparent.

7. The formulation according to claim 1, wherein said at least one ketone solvent is selected from dimethyl ketone (acetone), methylethyl ketone (MEK), diethyl ketone (DEK), methyl- wø-butyl ketone (MIBK) and a combination thereof.

8. The formulation according to claim 7 wherein said at least one ketone solvent is a combination of two ketone solvents.

9. The formulation according to claim 1, wherein said PVC resin has a k- value between 50 and 58.

10. A formulation comprising pure homopolymer PVC (polyvinyl chloride) resin, at least one ketone solvent and at least one additive selected from antioxidants, biocides, antifoaming agents, antifog additives, viscosity modulators, adhesion promoters, antiblocking agents, antitack agents, slip agents, flame retardant agents, fillers, antistatic agents, copolymers, homopolymers, metal powders, agents reducing flammability, heat stabilizers, UV stabilizers, light blockers, anti-corrosive and anti-erosive agents, glass fibers, pigments, and any combination thereof.

11. The formulation according to claim 10, wherein said additive is not a plasticizer.

12. A formulation comprising a pure homopolymer PVC (polyvinyl chloride) resin and at least one ketone solvent, provided that said formulation does not comprise one or more plasticizer.

13. The formulation according to claim 12, wherein said plasticizer is selected from dialkyl phthalates, alcohol derivates of phthalates, trialkyl phosphates, dialkyl adipates, and dialkyl azelates.

14. The formulation according to claim 13, wherein said formulation comprises at least one additive selected from antioxidants, biocides, antifoaming agents, antifog additives, viscosity modulators, adhesion promoters, antiblocking agents, antitack agents, slip agents, flame retardant agents, fillers, anti-static agents, copolymers, homopolymers, metal powders, agents reducing flammability, heat stabilizers, UV stabilizers, light blockers, anti-corrosive and anti-erosive agents, glass fibers, pigments, and any combination thereof.

15. A formulation comprising pure homopolymer PVC (polyvinyl chloride) resin, at least one ketone solvent and at least one additive selected from solvents, antioxidants, biocides, antifoaming agents, antifog additives, viscosity modulators, adhesion promoters, antiblocking agents, antitack agents, slip agents, flame retardant agents, fillers, anti-static agents, copolymers, homopolymers, metal powders, agents reducing flammability, heat stabilizers, UV stabilizers, light blockers, anti-corrosive and anti- erosive agents, glass fibers, pigments, and any combination thereof, provided that said at least one additive is not a plasticizer.

16. A formulation according to any one of claims 10 to 15, further comprising an aromatic solvent.

17. A formulation according to any one of claims 10 to 16, further comprising an aromatic solvent.

18. A method for the manufacture of a formulation according to claim 1, said method comprising adding into at least one ketone solvent an amount of a homopolymer PVC resin and mixing the resulting mixture until a transparent solution is obtained.

19. The method according to claim 18, wherein said mixing is performed at ambient temperature.

20. Use of a formulation according to any one of claims 1 to 17, or a formulation prepared according to claims 18 or 19, for coating at least one article or surface.

21. The use according to claim 20, wherein said coating is achieved by at least one method selected from spraying, brushing, washing, and dipping.

22. The use according to claim 20, wherein said at least one article or surface is selected from cement, metal articles or sheets, wood products, plastics, alloys made articles or sheets, floors, walls, appliances, dishes, kitchen appliances, clean room appliances and articles contained therein, sanitary appliances, fabrics, clothing, military appliances, and machinery or parts thereof.

23. A PVC-based multilayer sheet assembly having at least one base film and at least one layer of PVC.

24. The PVC-based multilayer sheet assembly according to claim 23, wherein said at least one layer of PVC is a composite of PVC comprising at least one additive.

25. The PVC-based multilayer sheet assembly according to claim 23, wherein said at least one layer of PVC is coated on said at least one base film.

26. The PVC-based multilayer sheet assembly according to claim 23, wherein said base film is coated with PVC on each of its faces.

27. The PVC-based multilayer sheet assembly according to claim 25, wherein said base film being coated with PVC on each of its faces is further treated with a coat of composite PVC comprising an adhesive.

28. The PVC-based multilayer sheet assembly according to claim 26, wherein said at least one surface is selected from cement, wood, metal, metal alloy and plastic.

29. The PVC-based multilayer sheet assembly according to claim 23 having at least one base layer and at least one PVC-based layers.

30. The PVC-based multilayer sheet assembly according to claim 29, comprising at least one base layer, at least one layer of PVC; and optionally, at least one layer of composite PVC containing at least one additive.

31. The PVC-based multilayer sheet assembly according to claim 30 further comprising at least one layer of a reinforcing material.

32. The PVC-based multilayer sheet assembly according to claim 31, comprising at least one first layer of PVC, at least one first layer of composite PVC containing at least one additive, at least one base layer; and optionally at least one layer of reinforcing material.

33. The PVC-based multilayer sheet assembly according to claim 32, comprising a first layer of PVC, a first layer of composite PVC containing at least one additive, a layer of metallic material, a second layer of composite PVC containing at least one additive, a layer of reinforcing material; and a second layer of PVC.

34. The PVC-based multilayer sheet assembly according to claim 33, wherein said first layer of composite PVC containing at least one additive is on top of said first layer of PVC, said layer of metallic material is on top of said first layer of composite PVC containing at least one additive, said second layer of composite PVC containing at least one additive is on top of said layer of metallic material, said layer of reinforcing material is on top of said second layer of composite PVC containing at least one additive, and said second layer of PVC is on top of said layer of reinforcing material.

35. The PVC-based multilayer sheet assembly according to any one of claims 23 to 34, wherein said layers are essentially coextensive.

36. The PVC-based multilayer sheet assembly according to any one of claims 23 to 34, wherein said additive is selected from heat and UV stabilizers, light blocker, pigments, fillers, flame retardants, anti-static agent, anti-corrosive agent, anti-erosive, modulator of chemical adhesiveness, homopolymers or copolymers, metal powders or solutions, salts, softening agents, dissolving agents, plasticizers, stabilizers or any combination thereof.

37. The PVC-based multilayer sheet assembly according to any one of claims 23 to 34, wherein said base film is a metal foil of any metal or alloy.

38. The PVC-based multilayer sheet assembly according to claim 37, wherein said metal foil is aluminum foil.

39. The PVC-based multilayer sheet assembly according to any one of claims 23 to 34, wherein said base film is a fibrous sheet made of any type of fiber.

40. The PVC-based multilayer sheet assembly according to any one of claims 23 to 34, wherein said reinforcing material is a metal foil of any metal or alloy.

41. The PVC-based multilayer sheet assembly according to any one of claims 23 to 34, wherein said reinforcing material is a fibrous sheet made of any type of fiber.

42. The PVC-based multilayer sheet assembly according to claim 23 being a three- layer sheet.

43. The PVC-based multilayer sheet assembly according to claim 23 being a four- layer sheet.

44. The PVC-based multilayer sheet assembly according to claim 23 being a five- layer sheet.

45. The PVC-based multilayer sheet assembly according to claim 23 being a six- layer sheet.

46. The PVC-based multilayer sheet assembly according to claim 23 having between 6 and 10 layers.

47. The PVC-based multilayer sheet assembly according to claim 23 having at least 6 layers.

48. A packaging enclosure made of a PVC-based multilayer sheet assembly according any one of claims 23 to 45.