WO1997033749A1

WO1997033749A1 - Composite structure having a porous surface and a multilayer film laminated thereto

Info

Publication number: WO1997033749A1
Application number: PCT/US1997/003582
Authority: WO
Inventors: William Dale Maag; Joey Carico Carico; James Carl Williams
Original assignee: Eastman Chemical Company
Priority date: 1996-03-11
Filing date: 1997-03-07
Publication date: 1997-09-18
Also published as: ID16220A

Abstract

This invention relates to a composite structure having a porous surface and a multilayer film laminated to the porous surface. The multilayer film comprises a copolyester layer and a polymer layer wherein the copolyester layer is positioned between the substrate and the polymer layer. The polymer layer has a Rockwell Hardness value as determined by ASTM Method D785 of greater than or equal to R90. The composite structure is useful for interior or exterior applications, particularly as a re-usable concrete form board.

Description

COMPOSITE STRUCTURE HAVING A POROUS SURFACE AND A MULTILAYER FILM LAMINATED THERETO

This is an ORIGINAL application based on the PROVISIONAL Serial No. 60/013,124 filed March 11, 1996.

Field of the Invention

This invention relates to a composite structure having a porous surface and a multilayer film laminated to the porous surface. The composite structure is particularly useful as a re—usable concrete form board.

Background of the Invention

Concrete form boards are used in the construction industry for setting and curing of concrete into specific shapes and dimensions. Uncoated concrete form boards cannot be re—used or only re—used once or twice because of an appreciable amount of concrete remains on the form, while leaving a rough concrete surface. There are different methods in the art on how to provide improved, re—usable concrete form boards. However, ordinary plywood, usually treated on the surface with a mold release agent such as mineral oil, motor oil, or paraffin oil, is still being used most frequently. While these concrete form boards provide ease of release of cement from the boards without damaging the finish of the cement surface, the form boards can only be re—used once or twice.

More sophisticated concrete form boards may be made by treating fir plywood with a penetrating coating of an epoxy resin followed by a polyurethane coating. These two coatings are fused and cured under thermosetting conditions. The epoxy/urethane resin coatings are, however, difficult to apply and still require the application of a release agent. Alternatively, a phenolic resin impregnated paper overlay may be bonded to one side of a plywood panel. This overlay allegedly tends to bridge the gaps and cracks which would normally occur and have reasonably low water penetration.

Canadian Patent No. 931,486 discloses concrete form boards which have a layer of polyethylene laminated to a wood panel. Canadian Patent No. 918,896 discloses a method for forming concrete form boards comprising erecting and securing a form for said structure, pouring concrete into the form, allowing the concrete to cure and thereafter removing the form from the cured concrete. The form consists of wooden panels coated with a layer of polyethylene on the side adjacent the concrete to be poured. A disadvantage associated with the use of such polyolefins, however, is poor adhesion of the polyolefin to the wood panel. Therefore, it is necessary to apply a primer to the wood panel before laminating the polyolefin to the primed surface to increase the adhesion properties.

U.S. Patent No. 5,510,198 discloses a re—usable cement form consisting of a film laminated to a wooden substrate. The film contains a polyolefin layer which contacts the cement and a copolyester layer, between the polyolefin layer and wood, which acts as an adhesive. The copolyester is prepared from terephthalic acid, ethylene glycol and diethylene glycol. This film displays good adhesion and alkaline resistance, however, it lacks sufficient durability for many applications.

Summary of the Invention

Accordingly, it is an object of this invention to provide a composite structure which exhibits good barrier properties for use in construction and building applications. It is another object of this invention to provide a composite structure having a substrate with a porous surface wherein the porous surface is rendered nonporous by a durable coating or film which adheres to the substrate without the necessity of applying a primer to the porous surface of the substrate before applying the film.

It is a further object of this invention to provide a re—usable concrete form board having a coating which firmly adheres to the board, which readily releases from cement poured in contact with the coating and which is sufficiently durable to withstand repeated uses without significant deterioration or degradation.

With regard to the foregoing, the present invention provides a composite structure which comprises:

(A) a substrate having a porous surface;

(B) a multilayer film laminated on said porous surface of said substrate comprising:

(1) a copolyester layer wherein the copolyester comprises a dicarboxylic acid component containing at least 90 mole % terephthalic acid and 0 to 10 mole % isophthalic acid, and a diol component containing 20 to 40 mole % diethylene glycol and 60 to 80 mole % ethylene glycol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol; and

(2) a polymer layer wherein the polymer has a Rockwell Hardness value as determined by ASTM Method D785 of greater than or equal to R90 and is selected from the group consisting of acrylonitrile—butadiene—styrene, polyvinyl chloride, polyamide, cellulose acetate, acrylic, polystyrene, semicrystalline or crystallized polyesters, urethane, and combinations thereof, wherein the copolyester layer is positioned between the substrate and the polymer. According to another aspect of the present invention, a method is provided for preparing a composite structure which comprises:

(I) coextruding a multilayer film comprising:

(1) a copolyester layer wherein the copolyester comprises a dicarboxylic acid component containing at least 90 mole % terephthalic acid and 0 to 10 mole % isophthalic acid, and a diol component containing 20 to 40 mole % diethylene glycol and 60 to 80 mole % ethylene glycol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol; and (2) a polymer layer wherein the polymer has a

Rockwell Hardness value as determined by ASTM Method D785 of greater than or equal to R90 and is selected from the group consisting of crystallized polyesters, acrylics, polystyrenes, cellulosics, poly(vinyl chloride) , polyamide, silicone, urethane, and combinations thereof, and

(II) laminating the multilayer film to a substrate having a porous surface wherein the copolyester layer is positioned between the substrate and the polymer.

The invention provides a composite structure especially well suited for making concrete forms which exhibits improved properties over prior structures. In particular, the multilayer film adheres well to the porous surface of most woods used in making forms, and the outer polymer layer of the film performs better than previously used materials when subjected to repeat uses the abrasive/deforming forces imposed by concrete compositions applied against the surface. Detailed Description of the Invention

The present invention relates to a composite structure. The composite structure comprises a substrate having a porous surface and a multilayer film laminated to the porous surface of the substrate. The multilayer film comprises a copolyester layer and a polymer layer wherein the copolyester layer is positioned between the substrate and the polymer layer. The substrate of the present invention may be made of any material provided that the substrate has at least one porous surface. Suitable substrates include, for example, natural and synthetic wood, particle board, fiberboard, hardwood plywood, softwood plywood, chipboard, ceramic, and laminates including those containing a layer of metal such as aluminum foil having a surface ply or veneer of wood. The porous substrate is preferably wood, more preferably plywood.

The multilayer film is prepared from a copolyester layer and a polymer layer. The copolyester has a dicarboxylic acid component containing at least 90 mole % terephthalic acid and 0 to 10 mole % isophthalic acid, and a diol component containing 20 to 40 mole % diethylene glycol and 60 to 80 mole % ethylene glycol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol. Preferably, the diol component of the copolyester contains 32 to 40 mole % diethylene glycol and 60 to 68 mole % ethylene glycol.

The present inventors have determined that if the diethylene glycol content of the diol component is less than 20 mole percent, the melting point of the copolyester is too high to be reactivated by thermocompressing at 400°F. If the diethylene glycol content of the diol component is greater than 40 mole percent, the glass transition temperature is too low, making the copolyesters difficult to handle in bulk and coated form.

The dicarboxylic acid component of the copolyester may optionally be modified with up to 10 mole percent of one or more different dicarboxylic acids other than terephthalic acid and isophthalic acid. Such additional dicarboxylic acids include aromatic dicarboxylic acids preferably having 8 to 14 carbon atoms, aliphatic dicarboxylic acids preferably having 4 to 12 carbon atoms, or cycloaliphatic dicarboxylic acids preferably having 8 to 12 carbon atoms. Specific examples of dicarboxylic acids which may be included with terephthalic acid and isophthalic acid are: phthalic acid, naphthalene— ,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl—4,4'— icarboxylic acid, succinic, glutaric acid, adipic acid, azelaic acid, and sebacic acid. Copolyesters may be prepared from one or more of the above dicarboxylic acids. It should be understood that use of the corresponding acid anhydrides, esters, and acid chlorides of these acids is included in the term "dicarboxylic acid".

In addition, the copolyester may optionally be modified with up to 10 mole percent, of one or more different diols other than ethylene glycol and diethylene glycol. Such additional diols include cycloaliphatic diols preferably having 6 to 20 carbon atoms or aliphatic diols preferably having 3 to 20 carbon atoms. Specific examples of diols which may be included with ethylene glycol and diethylene glycol are: triethylene glycol, 1,4—cyclohexanedimethanol, propane— 1,3-diol, butane-l,4-diol, pentane-1,5—diol, hexane-1,6- diol, 3—methylpentanediol—(2,4) , 2—methylpentanediol— (1,4), 2,2,4—trimethylpentane—diol—(1,3) , 2—ethylhexane— diol-(1,3), 2,2-diethylpropane-diol-(1,3), hexanediol- (1,3), 1, -di-(hydroxyethoxy)-benzene, 2,2,-bis-(4- hydroxycyclohexy1)-propane, 2,4—dihydroxy—1,1,3,3- tetramethy1—cyclobutane, 2,2—bis-(3—hydroxyethoxy— phenyl)-propane, and 2,2—bis(4-hydroxypropoxyphenyl)- propane. Copolyesters may be prepared from two or more of the above diols.

The copolyester may also contain small amounts of trifunctional or tetrafunctional comonomers such as trimellitic anhydride, trimethylolpropane, and pentaerythritol.

The copolyester has an inherent viscosity of 0.4 to 1.5 dL/g, preferably 0.5 to 0.9 dL/g. Copolyesters containing substantially only terephthalic acid, diethylene glycol and ethylene glycol are preferred. The copolyesters of the present invention can be prepared by conventional polycondensation procedures well— nown in the art. Such processes include direct condensation of the dicarboxylic acid(s) with the diols or by ester interchange using a dialkyl dicarboxylate. For example, dimethyl terephthalate is ester interchanged with the diols at elevated temperatures in the presence of a catalyst. Typical catalysts which may be used include titanium alkoxides such as acetyl triisopropyl titanate, tetraisopropyl titante, and tetraisobutyl titanate; germanium; dibutyl tin dilaurate; and combinations of zinc, manganese or magnesium acetates or benzoates. Germanium and antimony may be in the form of oxides, organic salts, and glycolates such as antimony oxide or antimony triacetate. The copolyester may also be subjected to solid state polymerization methods.

Many other ingredients can be added to the copolyester to enhance the performance properties of the copolyester. For example, antioxidants, denesting agents, antiblocking agents, metal deactivators, colorants, phosphate stabilizers, mold release agents, fillers such as talc and formica, silica, glass beads, glass fibers, nucleating agents, ultraviolet light and heat stabilizers, lubricants, flame retardants and the like, can be included herein. All of these additives and the use thereof are well known in the art. Any of these compounds can be used as long as they do not deleteriously effect the physical, mechanical, or adhesive properties of the copolyester.

The polymer layer of the multilayer film is prepared from a polymer having a Rockwell Hardness value as determined by ASTM Method D785 of greater than or equal to R90. Any polymer can be used provided it can be extruded into a film or applied to the surface of an extruded film directly following extrusion. The polymer must also be alkaline resistant. The polymer provides a hard, scratch resistant surface to the composite structure. The polymer is selected from acrylonitrile— butadiene—styrene, polyvinyl chloride, polyamide, cellulose acetate, acrylic, polystyrene, semicrystalline or crystallized polyesters, and urethane. Combinations of polymers may also be used. In addition, monomers used to prepare the above—named polymers may be reacted to prepare polymers that are within the scope of the present invention.

Acrylonitrile-butadiene—styrene resin (ABS resin) is a rigid thermoplastic resin prepared from acrylonitrile, butadiene and styrene monomers. ABS resins are graft polymers consisting of an elastomeric polybutadiene or rubber phase, grafted with styrene and acrylonitrile monomers for compatibility, dispersed in a rigid styrene—acrylonitrile matrix. ABS resins are characterized by the following properties: dimensional stability over a temperature range of — 0°C to +71°C, tensile strength of about 6500 psi, flexural strength of about 10,000 psi. Preferred ABS resins are CEVIAN 400T having a Rockwell Hardness value of R112, available from Hoerchst Celanese, and LUSTRAN ABS 860 having a Rockwell Hardness value of R110, available from Monsanto Chemical Company.

Polyvinyl chloride (PVC resin) is a thermoplastic polymer which is prepared by a free radical polymerization of vinyl chloride monomer. A preferred PVC resin is COMALLOY 310-3010 PVC containing 10% glass fiber and having a Rockwell Hardness value of R97, available from Comalloy International Corporation.

Polyamide resins are thermoplastic polymers which contain an amide group —CONH. Polyamide resins are characterized by a tensile strength up to 8 g/denier

(approximately 100,000 psi). Suitable polyamide resins, for example, include Nylon 66, Nylon 6, Nylon 4 and Nylon 610. Nylon 66 is a condensation product of adipic acid and hexamethylenediamine. Nylon 6 is a polymer of caprolactam. Nylon 4 is a polymer of butyrolactam (2— pyrrolidone) . Nylon 610 is a condensation product of sebacic acid and hexamethylenediamine. Preferred polyamide resins are Nylon 6 having a Rockwell Hardness value of R118, available from Custom Resins, Inc, and ZYTEL 330 which is an amorphous nylon having a Rockwell Hardness value of R128, available form Dupont Chemical Company.

Cellulose acetate is a thermoplastic resin. Cellulose acetate is a cellulose ester in which the cellulose is not completely esterified by acetic acid. The cellulose ester is prepared by reacting cellulose with acetic acid or acetic anhydride. A preferred cellulose acetate resin is TENITE 036—H5 having a Rockwell Hardness value of R110, available from Eastman Chemical Company. Acrylic resin is a thermoplastic polymer or copoly er of acrylic acid, methacrylic acid, esters of acrylic acid or methacrylic acid, or acrylonitrile. Examples of acrylate esters include: methyl acrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, isooctyl acrylate, isodecyl acrylate, lauryl acrylate, stearyl acrylate, phenoxethyl acrylate, methoxyethyl acrylate, benzyl acrylate, fur l acrylate, methylfuryl acrylate, butylfuryl acrylate, tetrahydrofurfuryl acrylate, ethoxyethyl acrylate, 2— thylhexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, isobornyl acrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate.

Examples of methacrylate esters include: methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, isodocyl methacrylate, lauryl methacrylate, stearyl methacrylate, isobornyl methacrylate, phenyl methacrylate, benzyl methacrylate, propylene glycol methacrylate, tetrahydrofurfuryl methacrylate, hydroxylethyl methacrylate, and hydroxypropyl methacrylate. A preferred acrylic resin is NSC A-101 having a Rockwell Hardness value of R120, available from Thermofil, Inc.

Polystyrene is a thermoplastic resin prepared by polymerizing styrene monomer. A preferred styrene resin is STYRON 421 having a Rockwell Hardness value of R110, available from Dow Chemical Company.

Semicrystalline or crystalline polyesters are selected from polyethylene terephthalate, bis(ethoxylated) Bisphenol A, bis(propoxylated)

Bisphenol A, polyethylene oxide diol, and polypropylene oxide diol. A preferred polyester AMOCO 1046 having a Rockwell Hardness value of R94, available from Amoco Chemical Corporation. Combinations of monomers used for preparing the above—described resins may also be polymerized to form polymers.

Adhesion between the polymer layer and the copolyester layer may be enhanced by a "tie layer" between the polymer layer and copolyester layer. In other words, a three layer coextrusion may be used where the layers are: polymer layer, tie layer, and copolyester layer, respectively. The tie layer includes any material that exhibits adhesive properties that is extrudable into a film. For example, the tie layer may be prepared from functionalized polyolefins such as ionomer/e hylene copolymer, vinyl acetate/ethylene copolymer, methacrylic acid/ethylene copolymer, methyl acrylate/ethylene copolymer, anhydride/acrylate/ethylene terpolymer, and hydrocarbon tacifying resins.

The copolyester layer and polymer layer, and optional tie layer, are coextruded either by simultaneous coextrusion of the respective film—forming layers through independent orifices of a ulti—orifice die, and thereafter uniting the still molten layers, or by single—channel coextrusion in which molten streams of the respective film—forming layers are first united within a channel leading to a die manifold, and thereafter extruded together from the die orifice under conditions of streamline flow without intermixing, to form a multilayer film. The multilayer film has a thickness of 0.1 to 15 millimeters, preferably, 2 to 15 millimeters, more preferably about 3 millimeters.

Optionally, a coating of primer may be applied to the porous surface of the substrate prior to applying the copolyester layer and polymer layer, respectively. The addition of a primer may improve the hardness characteristics of the substrate and also the adhesion between the substrate and the copolyester layer. Suitable primers, for example, include urethanes and epoxides.

The multilayer film of the present invention is laminated to the substrate, as described above, under heat and pressure or optionally by radio frequency energy. Higher temperatures and pressures and longer periods of time tend to increase the penetration of the multilayer film into the porous surface of the substrate. Preferably, lamination is conducted at a pressure of 0 psig to 1,000 psig at a temperature of 200°F to 500°F. More preferably, lamination is conducted at a temperature of about 300°F and a pressure of about 200 psi for about one minute.

The composite structure of the present invention is useful for interior or exterior applications. For example, the composite structures may be used as bench tops, re—usable concrete form boards, boxes, walls and floors for trailers, and signs.

The following nonli iting examples illustrate further the practice of the invention:

Example 1

An overlay consisting of acrylonitrile—butadiene— styrene polymer and a copolyester containing 100 mole % terephthalic acid, 63 mole % ethylene glycol and 37 mole % diethylene glycol was extruded into a multilayer film. The copolyester had a starting inherent viscosity of 0.77 dL/g. The copolyester layer was 0.75 millimeters thick and the acrylonitrile—butadiene—styrene polymer layer was 0.75 millimeters thick. The multilayer film was pressed onto a sanded yellow poplar plywood core at 250 psi and 250°F for 3 minutes to form a composite structure.

The composite structure was made into a box with the multilayer film overlay facing the interior of the box. Cement was poured into the box, settled, and allowed to cure. The hardened cement did not adhere to the sides of the box and was easily removed from the box. The composite structure remained in excellent condition.

Example 2

An overlay consisting of acrylonitrile—butadiene— styrene polymer, ethylene—based terpolymer tie layer commercially available as MITSUI ADMER AT—469 from Mitsui & Co. , and copolyester containing 100 mole % terephthalic acid, 63 mole % ethylene glycol and 37 mole % diethylene glycol, respectively, was extruded into a multilayer film. The copolyester had a starting inherent viscosity of 0.77 dL/g. The copolyester layer was 0.75 millimeters thick, the tie layer was 0.25 millimeters thick, and the acrylonitrile—butadiene— styrene polymer layer was 0.75 millimeters thick. The multilayer film was pressed onto a sanded yellow poplar plywood core at 250 psi and 250°F for 3 minutes to form a composite structure.

Example 3

The composite structure in the form of a box which was prepared in Example 1 was refilled with cement which was allowed to cure. The hardened cement was removed from the box. The inside of the box was wiped clean with a damp cloth and was refilled with cement. This process was repeated six times. The hardened cement did not adhere to the sides of the box and was easily removed from the box each time. In addition, the composite structure remained in excellent condition even after being re—used six times.

While the invention has been described with particular reference to certain embodiments thereof, it will be understood that changes and modifications may be made which are within the skill of the art. The present invention is limited only by the claims that follow.

Claims

WHAT IS CLAIMED IS: l. A composite structure which comprises:

(A) a substrate having a porous surface;

(2) a polymer layer wherein the polymer has a Rockwell Hardness value as determined by ASTM Method D785 of greater than or equal to R90 and is selected from the group consisting of acrylonitrile—butadiene— styrene, polyvinyl chloride, polyamide, cellulose acetate, acrylic, polystyrene, semicrystalline or crystallized polyesters, urethane, and combinations thereof, wherein the copolyester layer is positioned between the substrate and the polymer.

2. The composite structure of Claim 1 wherein the dicarboxylic acid component of the copolyester is modified with up to 10 percent of one or more different dicarboxylic acids other than terephthalic acid.

3. The composite structure of Claim 2 wherein the dicarboxylic acid used to modify the copolyester is selected from the group consisting of phthalic acid, isophthalic acid, naphthalene-2,6— dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, dipheny1—4,4'— dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, and sebacic acid.

4. The composite structure of Claim 1 wherein the diol component of the copolyester is modified with up to 10 mole percent of one or more different diols other than ethylene glycol and diethylene glycol.

5. The composite structure of Claim 4 wherein the diol used to modify the copolyester is selected from the group consisting of triethylene glycol, 1,4— cyclohexanedimethanol, propane—l,3— iol, butane— 1,4-diol, pentane—1,5-diol, hexane—1,6—diol, 3- methylpentanediol—(2,4) , 2-methylpentanediol—(1,4) ,

2,2,4—trimethylpentane—diol—(1,3) , 2—ethylhexane— diol—(1,3), 2,2— iethylpropane—diol—(1,3) , hexanediol—(1,3) , 1,4—di—(hydroxyethoxy)—benzene, 2,2—bis—(4—hydroxycyclohexyl)—propane, 2,4— dihydroxy—1,1,3,3—tetramethyl—cyclobutane, 2,2—bis— (3—hydroxyethoxy—pheny1)—propane, and 2,2—bis—(4— hydroxypropoxypheny1)—propane.

6. The composite structure of Claim 1 wherein the substrate is wood.

7. The composite structure of Claim 1 wherein the multilayer film comprises an additional layer of an adhesive material between the polymer layer and the copolyester layer.

8. The composite structure of Claim 1 wherein the multilayer film has a thickness of 0.1 to 15 millimeters.

9. The composite structure of Claim 1 wherein the multilayer film additionally contains a dispersion of carbon black particles in at least one of the layers.

10. The composite structure of Claim 1 which is useful as a re—usable concrete form board.

11. A method for preparing a composite structure which comprises: (I) coextruding a multilayer film comprising:

(2) a polymer layer wherein the polymer has a Rockwell Hardness value as determined by ASTM method D785 of greater than or equal to R90 and is selected from the group consisting of crystallized polyesters, acrylics, polystyrenes, cellulosics, poly(vinyl chloride), polyamide, silicone, urethane, and combinations thereof, and (II) laminating the multilayer film to a substrate having a porous surface wherein the copolyester layer is positioned between the substrate and the polymer.