CA2155317A1 - A layered article prepared by spraying a thermoset resin to form each layer - Google Patents
A layered article prepared by spraying a thermoset resin to form each layerInfo
- Publication number
- CA2155317A1 CA2155317A1 CA 2155317 CA2155317A CA2155317A1 CA 2155317 A1 CA2155317 A1 CA 2155317A1 CA 2155317 CA2155317 CA 2155317 CA 2155317 A CA2155317 A CA 2155317A CA 2155317 A1 CA2155317 A1 CA 2155317A1
- Authority
- CA
- Canada
- Prior art keywords
- layer
- layers
- solid
- spraying
- layered
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B5/00—Hulls characterised by their construction of non-metallic material
- B63B5/24—Hulls characterised by their construction of non-metallic material made predominantly of plastics
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
- B29C41/08—Coating a former, core or other substrate by spraying or fluidisation, e.g. spraying powder
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
- B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
- B29C41/22—Making multilayered or multicoloured articles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C67/00—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00
- B29C67/24—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00 characterised by the choice of material
- B29C67/246—Moulding high reactive monomers or prepolymers, e.g. by reaction injection moulding [RIM], liquid injection moulding [LIM]
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2075/00—Use of PU, i.e. polyureas or polyurethanes or derivatives thereof, as moulding material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/30—Vehicles, e.g. ships or aircraft, or body parts thereof
- B29L2031/3067—Ships
- B29L2031/307—Hulls
Abstract
A layered structure has superior properties because it is prepared by spraying two part liquid resin polymers that chemically react very quickly to become solid, to form each layer. A novelty is preparing all layers from a thermoset resin, which is possible because all layers are added by a spraying means. Structures are formed into articles such as boat hulls, truck liners, bathtubs, and automobile parts, using suitable molds. The articles have desirable properties such as durability, and relatively light weights. Moreover, they are produced more rapidly and inexpensively than similar layered articles produced by other methods.
Description
A LAYERED ARTICLE PREPARED BY SPRAYING A
THERMOSET RESIN TO FORM EACH LAYER
Background of the Invention A layered structure has superior properties because it is prepared by spraying two part liquid resin polymers that chemically react very quickly to become solid, to form each layer. A novelty is preparing all layers from a thermoset resin, which is possible because all layers are added by a spraying means. Structures are formedinto articles such as boat hulls (canoes), truck liners, bathtubs, and automobile parts, 10 using suitable molds. The articles have desirable properties such as durability, and relatively light weights. Moreover, they are produced more rapidly and inexpensively than layered articles produced by other methods.
Layered articles have been prepared by a variety of methods using a variety of materials. The choice of materials and methods is dictated by the specifications of 15 the structure of the specific article to be produced and by the availability of the compositions and apparatus available at a particular point in time. For a multilayered, performed, deformable plastics part, a layering method requiring a heated mold for a first layer, and adding subsequent layers by moving the model through a curtain of flowing plastic is suggested in GB,A, 1, 374 829.
Layered structures have been produced using thermoplastics, for example, which do not have as desirable properties as thermoset resins. In EP A, 0 401 150 a layer of thermoplastic is covered with a "sprayed on layer of a preferably glass fiber-reinforced curable plastic." This is proposed for construction of bath tubs. Thestructures are less resilient, and the method of producing thermoplastic structures is 25 lengthier and more costly than a method for producing layered structures fromthermoset resins. Thermoplastics are polymers which soften under heat and are therefore amenable to molding by being injected or poured into cavities.
Thermoplastics are not amenable to application by spraying.
Gel coat layers have been sprayed on inner cores prepared by methods other than spraying, but this tends to produce relatively heavy structures. A spray gun was used to create a bath tub with a multicolored design and a polyester gel coat. (JP, A 59 103 716) Multilayered structures used for insulation have been described, for 5 example, in JP 60,201,934, that have a foam core and thermoplastic resin outersheets, but the design of this type of structure does not have to take into account damage to structural integrity, an important consideration for articles such as boat hulls and automobile parts.
Multilayered sheets have been formed by extruding plastic polypropylene and polystyrene followed by thermoforming using a vacuum. See W0 8,302,747.
Laminated structures have also been produced by injectional molding (EP 419829) 5 and rotational molding as described in U.S. Pat. No. 5,096,652. In rotational molding, the laminate is made while the molded structure is being formed. Rotational molding has been used to produce boat hulls having three layers of polyethylene, with the middle or intermediate layer containing a foaming agent. U.S. Pat. No.
4,913,944. The layers are formed by particulate plastic being released into the mold 10 cavity while the mold "rocks and rolls" in an oven, or at least goes in an oven at some point in the process. This process generally takes several hours, and requires a metal mold.
Fast-curing thermoset resins are relatively new compositions that form permanent and durable structures after being formed by heat or chemical reaction.
15 Reactive injection molding (RIM) can be used with thermoset resins by injecting the mold cavity with the resins, but the result is not layered. (See, e.g., "Le RIM par projection" 818 Plastiques Modernes et Elastomeres 36, 9, Nov. 1984 p. 68).
Layered compositions have advantages of incorporating desirable characteristics of different materials into one structure, and even creating synergistic improvements 20 over characteristics of the combined individual materials.
Thermoset polyesters, epoxys, polyurethanes, phenolics and other thermoset resins may be hand-layered, but this is time consuming and difficult due to the hand labor and the fact that some resins are slow setting. To increase tensile strength and stiffness, chopped glass fibres and foam may be added to layers. DE 3206468.
CA 2 1 553 ~ 7 A method of applying a composition to a structure is spraying. Generally spraying will result in one layer of CA2~ 553 17 a composition. However, spraying has been used to apply multilayers of polymers to wire strands, where the wire strands are layered within the layers of polymer. U.S.
4,891,086. A news report alludes to a resin spray gun for spraying "Rimspray" a urethane elastomer ("Reaction molding by spray gun," European Plastics News 10:45 (May, 1983). Spraying has not been applied to produce layers of two part thermoset resins .
There are problems in production of multilayered structures and in the nature of the articles produced by the methods in the art. Problems include costs due to expense of preparation of molds suitable for the methods and compositions in the art, 10 the length of time needed to prepare the structure, which increases cost and limits output, and difficulties in adapting to robotic manufacturing methods.
Therefore, there is a need to improve methods of preparing layered structures which could be quickly and inexpensively formed into articles such as boat hulls, (canoes), automobile and furniture parts, bathtubs, truck liners to protect against 15 abrasion and the weather, and the like. The improvements needed are to more quickly and efficiently accomplish the production of a more durable layered structure which is versatile in its applications. A goal of the present invention is to disclose and claim a method distinct from rotational molding, injection molding, blow molding, reactive injection molding, resin transfer molding (RTM), and extrusion molding, none 20 of which have achieved the goals stated herein. It is another aspect of the present invention to teach how to produce a structure resulting from the method that is distinct from laminated plastic sheets, including those with foam cores, and from structures that were not bound to each other by chemical reactions between the layers. The structure of the present invention has layers that do not dissociate. A
25 particular goal not addressed by the art is to produce canoes and liners for truck receptacles with layered two-part thermoset resin.
Summarv of the Invention - A layered structure with superior properties is prepared by spraying a two part thermoset resin to form layers. The structure is moldable into various articles (~A21 5531 7 such as boat hulls, automobile and furniture parts, bathtubs, and truck liners. The articles formed from the layered structure of the present invention are more durable, resilient, lightweight, and inexpensive, than are comparable articles produced by other methods and compositions.
The present invention is directed to a method for making a layered structure, where there may be from 1 to n layers. A structure that has two or more layers is called a "multilayered" structure. In particular, the invention relates a method of making a canoe and a liner for a truck receptacle. Another aspect is the canoe and the liner made in accordance with the invention.
The method includes the following steps:
a. Selecting a comPosition for a first laver.
The composition of the first layer is selected depending on criteria dictated by the type of article to be produced. The composition and structure of the first layer of a structure is determined by the specification for a particular application. In various 15 illustrative embodiments, the first layer may be composed of a resin, for example a two-part thermoset resin. Thermoset resins that are suitable for use in the present invention include resins that are characterized by elongation of at least 10%, and that are suitable for spraying. In a preferred embodiment, the resin is an elastomer, that is, a composition with a very high elongation, for example, 100%. Thermoset 20 polymers (resins) when molded to a specific shape cannot be subsequently softened.
Compositions that are suitable for the purposes of the present invention includepolyurea and a mixture of polyurethane and polyester.
An advantage of fast-curing thermoset resins for the present invention is that the two-part resins harden or set very quickly after they are mixed and form very 25 durable structures. By quickly is meant within, for example, seconds or minutes as compared with hours needed for some compositions in the art used for pour molding, resin transfer molding, and injection molding to set.
For example, a thermoset resin formed of polyurea hardens or sets to form an article, within about 3-40 seconds, as compared with polyethylene used in rotational molding, which may require at least one hour to form an article, and some other compositions that take 8 hours to set, especially if the goal is to produce a multilayered article.
In a multilayered structure of the present invention, the layers may all be of different compositions, or may be of the same composition, or any combination thereof. In an illustrative embodiment, the composition of at least one of the layers other than the first layer, that is, a layer which forms an inner (intermediate, middle) layer of a multilayered structure, may be a foam layer. In an illustrative embodiment, 10 the foam layer is made by mixing a blowing agent such as water with the resin layer.
The water reacts with isocyanide to form carbon dioxide which introduces bubblesinto the resin, to form a foam. An advantage of using the same basic compositionin all layers, is to minimize delamination (undesirable separation of the layers) caused by differential response of layers of different compositions to the environment.There may be any number of layers in the layered article, from 1 to n. The upper limit is dependent on the applications for which the structures are to be used.
In a preferred embodiment, there are three layers composed of an outer and an inner resin layer (or substrate), and an intermediate foam layer. This type of structure, which may be referred to as a "sandwich", is useful for forming into an article such 20 as a canoe. Where there are layers beyond three, generally at least the inner and outer layers are solid resins, rather than foam. Generally, foam and solid layers will alternate. However, any combination of semi-solid or solid resins are within thescope of the present invention.
b. Spraving the composition onto a suitable supPort to form a laver.
, The first layer is designated as the layer that is emitted from a spraying apparatus first during the process of making the layered article. Generally, the first layer will constitute the outer layer (substrate) of the finished article. The first layer is sprayed onto a solid support. The solid support is generally a mold, but may be 5 any solid support that allows the first layer to harden in a manner suitable for a particular application. The solid support in the form of a mold, form or other suitable type, need not be prepared to a specific temperature, as are such supports used for other methods in the art. A suitable ambient air temperature is in the range of 15.5-65.5 C (60-150 F.) If pigments are to be added to a molded product, they are usually added to the mold prior to the first layer as paint, or are added to the first layer, or both. If the article is to be exposed to ultraviolet light, the first sprayed layer may contain an ultraviolet resistant paint, generally in a layer of about .0254 to .1016 mm (1 to 4 mil) thick. This procedure is referred to as (in mold painting.) The spraying of the resin to form layers is accomplished by any apparatus that is capable of distributing a thermoset resin, or a comparable composition, into a layer.
Examples of spraying apparatus include manually operated spray guns, a plurality of spray guns operated sequentially, a spray gun with multiple nozzles, a single spray gun used repeatedly, or a robotic spraying apparatus. The robotic method is likely to 20 produce more desirable thickness in layers than a manually controlled spraying apparatus.
c. Repeating steP a and b as manv times as required to form the multilavered structure .
As mentioned in parts a and b, the first layer is generaily sprayed onto a solid25 support that is provided initially, for example, a mold. An advantage of the present invention is that the mold does not have to be heavy, resistant to extreme temperatures, or have complex 094/14587 PCT~S93/12303 2~5~3~7 and tight closing means. In fact, a mold may be made of the same resins used for the layers of the structure produced by methods of the present invention.
Subsequent layers use as their solid support, a previously sprayed layer. The second layer may be sprayed after the first layer sets up, although spraying of subsequent layers could wait for a long time, as long as no cont~in~nts, such as oil or silicone-laden air, affect the surface.
The second sprayed layer is sprayed onto the first layer, wherein the second layer adheres to the first layer. The third sprayed layer is sprayed onto the second layer, and so forth. This process is repeated until all layers required for a particular article are sprayed. Other materials, such as metal reinforcements or ribs, may be incorporated into the layers.
An article is defined as any structure which is formed from a layered structure, wherein the layers have been formed by the methods of the present invention. The term "article~' includes both formed and unformed structures wherein "formed" includes structures shaped into recognizable shapes and "unformed" includes structures that are not useful without further processing.
The methods of the present invention are suitable to make any multilayered article including a boat hull, such as a canoe hull, a liner for a truck receptacle, automobile parts such as fenders, and furniture.
Advantages of the present invention include quick, therefore, more efficient means of producing multilayered articles. Cost is reduced because production time is dramatically reduced, and the only apparatus required is a spraying apparatus. The mold does not have to be heated prior to spraying, and may be comparatively inexpensively and simply constructed.
~n important advantagc for thc cn~ironmcnt rc~ulting fro... u_ing f~st ~-ctting rc~in~ i~ that 1~E 60nt-~nant~
An important advantage for the environment resulting from using fast-setting resins is that less contaminants escape, e.g., isocyanate, due to a reduced timeduring which compositions are volatile.
An aspect of the present invention is the layered structure formed by the 5 method disclosed. The structure is composed of one or a plurality of layers, depending on the nature of the application o~ the structure. A suitable composition of the first layer of the structure includes a thermoset resin. A suitable composition of at least one of the inner layers of the suitable includes a foam, for example, a foam composed of water and resin. The resin is a thermoset resin. There is no size 10 limitation associated with an article produced by the methods of the present invention, although it is most suitable for relatively large articles, such are exemplified herein.
The advantages of the layered structure of the present invention include flexibility of construction and of composition of the layers. The layers may be thicker 15 or thinner in areas where a thicker or thinner thickness is advantageous, in contrast to what can be achieved using other methods, for example rotational molding or blow molding. If robotic spraying is used, layer thickness is controlled. Additives may be put in the layers such as pigment, and metal reinforcements. Another advantage is that when used for a molded article, the composition applied by the methods of the 20 present invention, has a "mold memory," rather than a sheet memory as in the methods of the art which heat sheets and mold them into forms. Thermoplastic type compositions are characterized by a tendency to revert to their original form from a subsequently imposed form, such as that imparted by the thermo-formed molding process. Therefore, articles of the present invention are more responsive to repairs 25 especially after being damaged, for example, by blows to the article.
.
The layers of the structure may be any thickness, but a preferred range is from .0508-1.016 mm (2-40 mil). Layers may be the same or different thicknesses when compared to each other. Layers of the same composition may be accumulated to increase the thickness of a particular composition layer, e.g., from to 1.016 mm to 5 50.8 mm (40 mil to 2 inches). The number of layers will be a function of the thickness of an individually sprayed layer, and the number of repetitions.
Detailed DescriPtion of the Preferred Embodiments Thermoset Resins Thermoset resins are suitable for the methods of the present invention if they 10 are capable of being applied to a solid support by spraying, and they have anelongation of at least 10 %. The resins are two-part liquid resins of polymers that chemically react very quickly to become solid. By a two part resin is meant a composition which is divided into two components which must be mixed in order for hardening to occur. By very quickly is meant in as little time as seconds. The exact 15 hardening time will vary with the specific composition.
In an illustrative embodiment, the resins comprise polyurea. In another embodiment, the resins comprise a hybrid polyurethane and polyester. A suitable composition is the EC Series 23, which is available from EniChem, Polyurethane Design Division,1448 V.F.W. Drive, Conyers, Georgia 30207. Characteristics of the 20 EC Series 23 are shown in Table 1. EC Resin System Series 23 is a 100% solid polyurea system. It has been used for reaction injection molding (RIM). For thatpurpose, key processing benefits are the adjustable gel time from 3 to 45 seconds, which was purported by the manufacturer to eliminate mold flowing problems.
"Fillers" are easy to process for enhanced properties; "optional internal molding 25 release" is available for optimizing cycle times.
The EC23 system enhances the quality of the molded part by minimizing sink marks and shrink. Also, paintability is said to be excellent using standard automotive paint and techniques.
TABLE 1: Characteristics of EC Series 23 PHYSICAL PROPERTIES:
EC EC
Specific Gravity 1.12 1.120 Thickness .125 .125 Tensile Strength atm 238.161 265.379 (3.5K) (3.9K) Elongation % 95 73 Flexural Modulus atm 5449.68 6804.6 (80K) (100K) Shore D 60D 65D
Notched Izod-lmpact 7 5 Linear Shrinkage 0.75 0.75 HeatSag-1 hr.@ 121.11C (250F) MOLDING CONDITIONS
ISO Temperature 32.22C 32.22C
(90F) (90F) Polyol Temperature 32.22C 32.22C
(90F) (90F) Mixing Pressure 136.092 atm 136.092 atm (2000 PSI) (2000PSI) Mix Ratio 1.14/1 PBW A/B 1 /1 PBW AB
Another resin suitable for use in the present invention is the EniChem series EC 242.
Characteristics of that series of resins are presented in Table 2. EC Resin Systems Series 242 is a high-modulus hybrid polyurea that was designed for high productivity RIM production. Gel times are adjustable from 5 to 45 seconds implemented by 30 catalyst changes. According to the manufacturer, EC 242 provides excellent green strength and good release characteristics from the mold. EC Series 242 has excellent impact strength with minimal heat sag up to 135C (275).
TABLE 2: Characteristics of EC Series 242 5PHYSICAL PROPERTIES:
EC EC
242-21 242-25 ASTM Method Density 68PCF 68PCF D 1622 Hardness, Shore D 72 75 D 2240 Tensile Strength 360.644 atm 401.471 atm D 412 (5300 PSI) (5900 PSI) Elongation @ Break 180% 140% D 412 Flexural Modulus @ 22C 10207 atm 15174.258 atm D 790 (150,000 PSI) (223,000 PSI) Heat Sag . 101.6mm "4" "overhang 1 hr. @ 121 C 3.3 mm 3.3 mm D 3769 1 hr. @ 121 C (.13 ins.) (.13 ins.) D 3759 Notched Izod Impact 10.36 Kg/M .8295 Kg/M
(75. ft./lbs.) (6 ft./lbs.) **Post Cured @ 121 C for one hour Spraying Means Any means for spraying a two-part thermoset resin on to a solid support so 25 that the resin forms a layer, is suitable for purposes of the present invention. A spray gun may be ordered from Tel 908 Gusmer, 1 Gusmer Drive, P.O. Box 110, Lakewood, New Jersey 08701 -0110. Apparatus for spraying include the gun claimedin FR 2520639; and the thermal spray gun of U.S. 4,999,225.
While the invention is susceptible to various modifications and alternative 30 forms, specific embodiments C~155~17 thereof are shown by way of examples. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
5 EXAMPLE 1: Preparation of a Three-Layered Structure The first layer was composed of thermoset resin EC 491. It was sprayed on to the solid support using a spray gun and allowed to harden for one minute. A solid support was a fiberglass canoe mold.
The second layer was a foam layer produced by adding water to the non-10 isocyanate part of the resin system Part B. When the two parts are mixed, the waterreacts with the isocyanate in Part A to form C02. The more water that is added, the more C02 that is produced, and the more foaming action, or less density, results.
The second layer was sprayed on to the first and allowed to harden for two minutes.
The third layer was composed of the same resin used in the first layer. It was 15 sprayed onto the second layer and allowed to harden for 45 seconds.
The thickness of the first and third layers was about 1.27 mm (50 mil or .050 inches) .
The temperature at which the spraying was done was 22.22C (72).
EXAMPLE 2: Producing a Canoe The three layered structure of Example 1 is used to form the structure of the canoe .
The solid support used was a canoe-shaped mold. The moid that was used is a hand layed-up polyester fiberglass mold, the same type of mold that is used for a hand layed-up boat, such as a canoe or other fiberglass structure.
A mold is made using the same equipment and the same basic material as described in Example 1. This means a W094/14587 215 ~ 3 ~ 7 PCT~S93/1~03 ~ ,~ ,~ ,q Thc fir~t laycr w~s composcd of thcr~Ect rc~in Er 491. It was sprayed on to the solid support using a spray gun and allowed to harden for one minute. A solid support was a fiberglass canoe mold.
The second layer was a foam layer produced by add~ g water to the non-isocyanate part of the resin syste ~Part B. When the two parts are mixed, the water re ~ s with the isocyanate in Part A to form CO2. The ~ore water that is added, the more CO2 that is prod~ ed, and the more foaming action, or less density/ results. The second layer was sprayed on to the f~ st and allowed to harden for two minutes.
The third layer was compos ~ of the same resin used in the first layer. It was s ~ayed onto the second layer and allowed to harden for ~5 seconds.
The thicknecs of th~first and third layers was about 50 mil or .050 inche~
The temperatu~ at which the spraying was done was EXAMPLE 2: P~ ducing a Canoe The t~ ee layered structure of Example 1 is used to form t ~ structure of the canoe.
~ he solid support used was a canoe-shaped mold. The m~ d that was used is a hand layed-up polyester / iberglass mold, the same type of mold that is used for / a hand layed-up boat, such as a canoe or other fiberglass / structure.
/ A mold is made using the same equipment and the same ba~ic ~-t~rial aE dcscribcd in ~Y~rlc 1. Thie ~can~ a part can be duplicated by waxing the part, spraying the support as described in Example 1 (to create a mold), pulling the part from the mold, waxing the mold, spraying the mold again as in Example 1, to duplicate the part.
EXAMPLE 3: Manufacturing a Liner for a Truck Cavity A liner that fits snugly into the cavity of a truck is desirable to protect the basic truck finish from abrasion, for example, due to articles transported in the W094114587 215 ~ 31~ PCT~S93/1~03 cavity of a pick-up truck, and from the weather. Liners available in the art generally are composed of polyethylene, and must be attached to the truck with bolts and rivets. The attaching process itself, violates the integrity of the truck finish. Another disadvantage of the liners currently available, is that they are not readily removed.
Using the methods and compositions of the present invention, superior truck liners are produced that are resistant to weather and abrasion because of the strength and resistant surface properties that characterize thermoset polymers. In addition, because the polymer layers are sprayed directly on the truck cavity, no extra mold is needed. This reduces cost and improves fit of the liner to the truck cavity. If the interior of thetruck is waxed prior to spraying the first polymer layer, the liner may be readily removed by simply lifting it out.
Although the number and composition of the layers may vary depending on the nature of protection desired, the three layered structure of example 2 is a suitable structure for this purpose.
THERMOSET RESIN TO FORM EACH LAYER
Background of the Invention A layered structure has superior properties because it is prepared by spraying two part liquid resin polymers that chemically react very quickly to become solid, to form each layer. A novelty is preparing all layers from a thermoset resin, which is possible because all layers are added by a spraying means. Structures are formedinto articles such as boat hulls (canoes), truck liners, bathtubs, and automobile parts, 10 using suitable molds. The articles have desirable properties such as durability, and relatively light weights. Moreover, they are produced more rapidly and inexpensively than layered articles produced by other methods.
Layered articles have been prepared by a variety of methods using a variety of materials. The choice of materials and methods is dictated by the specifications of 15 the structure of the specific article to be produced and by the availability of the compositions and apparatus available at a particular point in time. For a multilayered, performed, deformable plastics part, a layering method requiring a heated mold for a first layer, and adding subsequent layers by moving the model through a curtain of flowing plastic is suggested in GB,A, 1, 374 829.
Layered structures have been produced using thermoplastics, for example, which do not have as desirable properties as thermoset resins. In EP A, 0 401 150 a layer of thermoplastic is covered with a "sprayed on layer of a preferably glass fiber-reinforced curable plastic." This is proposed for construction of bath tubs. Thestructures are less resilient, and the method of producing thermoplastic structures is 25 lengthier and more costly than a method for producing layered structures fromthermoset resins. Thermoplastics are polymers which soften under heat and are therefore amenable to molding by being injected or poured into cavities.
Thermoplastics are not amenable to application by spraying.
Gel coat layers have been sprayed on inner cores prepared by methods other than spraying, but this tends to produce relatively heavy structures. A spray gun was used to create a bath tub with a multicolored design and a polyester gel coat. (JP, A 59 103 716) Multilayered structures used for insulation have been described, for 5 example, in JP 60,201,934, that have a foam core and thermoplastic resin outersheets, but the design of this type of structure does not have to take into account damage to structural integrity, an important consideration for articles such as boat hulls and automobile parts.
Multilayered sheets have been formed by extruding plastic polypropylene and polystyrene followed by thermoforming using a vacuum. See W0 8,302,747.
Laminated structures have also been produced by injectional molding (EP 419829) 5 and rotational molding as described in U.S. Pat. No. 5,096,652. In rotational molding, the laminate is made while the molded structure is being formed. Rotational molding has been used to produce boat hulls having three layers of polyethylene, with the middle or intermediate layer containing a foaming agent. U.S. Pat. No.
4,913,944. The layers are formed by particulate plastic being released into the mold 10 cavity while the mold "rocks and rolls" in an oven, or at least goes in an oven at some point in the process. This process generally takes several hours, and requires a metal mold.
Fast-curing thermoset resins are relatively new compositions that form permanent and durable structures after being formed by heat or chemical reaction.
15 Reactive injection molding (RIM) can be used with thermoset resins by injecting the mold cavity with the resins, but the result is not layered. (See, e.g., "Le RIM par projection" 818 Plastiques Modernes et Elastomeres 36, 9, Nov. 1984 p. 68).
Layered compositions have advantages of incorporating desirable characteristics of different materials into one structure, and even creating synergistic improvements 20 over characteristics of the combined individual materials.
Thermoset polyesters, epoxys, polyurethanes, phenolics and other thermoset resins may be hand-layered, but this is time consuming and difficult due to the hand labor and the fact that some resins are slow setting. To increase tensile strength and stiffness, chopped glass fibres and foam may be added to layers. DE 3206468.
CA 2 1 553 ~ 7 A method of applying a composition to a structure is spraying. Generally spraying will result in one layer of CA2~ 553 17 a composition. However, spraying has been used to apply multilayers of polymers to wire strands, where the wire strands are layered within the layers of polymer. U.S.
4,891,086. A news report alludes to a resin spray gun for spraying "Rimspray" a urethane elastomer ("Reaction molding by spray gun," European Plastics News 10:45 (May, 1983). Spraying has not been applied to produce layers of two part thermoset resins .
There are problems in production of multilayered structures and in the nature of the articles produced by the methods in the art. Problems include costs due to expense of preparation of molds suitable for the methods and compositions in the art, 10 the length of time needed to prepare the structure, which increases cost and limits output, and difficulties in adapting to robotic manufacturing methods.
Therefore, there is a need to improve methods of preparing layered structures which could be quickly and inexpensively formed into articles such as boat hulls, (canoes), automobile and furniture parts, bathtubs, truck liners to protect against 15 abrasion and the weather, and the like. The improvements needed are to more quickly and efficiently accomplish the production of a more durable layered structure which is versatile in its applications. A goal of the present invention is to disclose and claim a method distinct from rotational molding, injection molding, blow molding, reactive injection molding, resin transfer molding (RTM), and extrusion molding, none 20 of which have achieved the goals stated herein. It is another aspect of the present invention to teach how to produce a structure resulting from the method that is distinct from laminated plastic sheets, including those with foam cores, and from structures that were not bound to each other by chemical reactions between the layers. The structure of the present invention has layers that do not dissociate. A
25 particular goal not addressed by the art is to produce canoes and liners for truck receptacles with layered two-part thermoset resin.
Summarv of the Invention - A layered structure with superior properties is prepared by spraying a two part thermoset resin to form layers. The structure is moldable into various articles (~A21 5531 7 such as boat hulls, automobile and furniture parts, bathtubs, and truck liners. The articles formed from the layered structure of the present invention are more durable, resilient, lightweight, and inexpensive, than are comparable articles produced by other methods and compositions.
The present invention is directed to a method for making a layered structure, where there may be from 1 to n layers. A structure that has two or more layers is called a "multilayered" structure. In particular, the invention relates a method of making a canoe and a liner for a truck receptacle. Another aspect is the canoe and the liner made in accordance with the invention.
The method includes the following steps:
a. Selecting a comPosition for a first laver.
The composition of the first layer is selected depending on criteria dictated by the type of article to be produced. The composition and structure of the first layer of a structure is determined by the specification for a particular application. In various 15 illustrative embodiments, the first layer may be composed of a resin, for example a two-part thermoset resin. Thermoset resins that are suitable for use in the present invention include resins that are characterized by elongation of at least 10%, and that are suitable for spraying. In a preferred embodiment, the resin is an elastomer, that is, a composition with a very high elongation, for example, 100%. Thermoset 20 polymers (resins) when molded to a specific shape cannot be subsequently softened.
Compositions that are suitable for the purposes of the present invention includepolyurea and a mixture of polyurethane and polyester.
An advantage of fast-curing thermoset resins for the present invention is that the two-part resins harden or set very quickly after they are mixed and form very 25 durable structures. By quickly is meant within, for example, seconds or minutes as compared with hours needed for some compositions in the art used for pour molding, resin transfer molding, and injection molding to set.
For example, a thermoset resin formed of polyurea hardens or sets to form an article, within about 3-40 seconds, as compared with polyethylene used in rotational molding, which may require at least one hour to form an article, and some other compositions that take 8 hours to set, especially if the goal is to produce a multilayered article.
In a multilayered structure of the present invention, the layers may all be of different compositions, or may be of the same composition, or any combination thereof. In an illustrative embodiment, the composition of at least one of the layers other than the first layer, that is, a layer which forms an inner (intermediate, middle) layer of a multilayered structure, may be a foam layer. In an illustrative embodiment, 10 the foam layer is made by mixing a blowing agent such as water with the resin layer.
The water reacts with isocyanide to form carbon dioxide which introduces bubblesinto the resin, to form a foam. An advantage of using the same basic compositionin all layers, is to minimize delamination (undesirable separation of the layers) caused by differential response of layers of different compositions to the environment.There may be any number of layers in the layered article, from 1 to n. The upper limit is dependent on the applications for which the structures are to be used.
In a preferred embodiment, there are three layers composed of an outer and an inner resin layer (or substrate), and an intermediate foam layer. This type of structure, which may be referred to as a "sandwich", is useful for forming into an article such 20 as a canoe. Where there are layers beyond three, generally at least the inner and outer layers are solid resins, rather than foam. Generally, foam and solid layers will alternate. However, any combination of semi-solid or solid resins are within thescope of the present invention.
b. Spraving the composition onto a suitable supPort to form a laver.
, The first layer is designated as the layer that is emitted from a spraying apparatus first during the process of making the layered article. Generally, the first layer will constitute the outer layer (substrate) of the finished article. The first layer is sprayed onto a solid support. The solid support is generally a mold, but may be 5 any solid support that allows the first layer to harden in a manner suitable for a particular application. The solid support in the form of a mold, form or other suitable type, need not be prepared to a specific temperature, as are such supports used for other methods in the art. A suitable ambient air temperature is in the range of 15.5-65.5 C (60-150 F.) If pigments are to be added to a molded product, they are usually added to the mold prior to the first layer as paint, or are added to the first layer, or both. If the article is to be exposed to ultraviolet light, the first sprayed layer may contain an ultraviolet resistant paint, generally in a layer of about .0254 to .1016 mm (1 to 4 mil) thick. This procedure is referred to as (in mold painting.) The spraying of the resin to form layers is accomplished by any apparatus that is capable of distributing a thermoset resin, or a comparable composition, into a layer.
Examples of spraying apparatus include manually operated spray guns, a plurality of spray guns operated sequentially, a spray gun with multiple nozzles, a single spray gun used repeatedly, or a robotic spraying apparatus. The robotic method is likely to 20 produce more desirable thickness in layers than a manually controlled spraying apparatus.
c. Repeating steP a and b as manv times as required to form the multilavered structure .
As mentioned in parts a and b, the first layer is generaily sprayed onto a solid25 support that is provided initially, for example, a mold. An advantage of the present invention is that the mold does not have to be heavy, resistant to extreme temperatures, or have complex 094/14587 PCT~S93/12303 2~5~3~7 and tight closing means. In fact, a mold may be made of the same resins used for the layers of the structure produced by methods of the present invention.
Subsequent layers use as their solid support, a previously sprayed layer. The second layer may be sprayed after the first layer sets up, although spraying of subsequent layers could wait for a long time, as long as no cont~in~nts, such as oil or silicone-laden air, affect the surface.
The second sprayed layer is sprayed onto the first layer, wherein the second layer adheres to the first layer. The third sprayed layer is sprayed onto the second layer, and so forth. This process is repeated until all layers required for a particular article are sprayed. Other materials, such as metal reinforcements or ribs, may be incorporated into the layers.
An article is defined as any structure which is formed from a layered structure, wherein the layers have been formed by the methods of the present invention. The term "article~' includes both formed and unformed structures wherein "formed" includes structures shaped into recognizable shapes and "unformed" includes structures that are not useful without further processing.
The methods of the present invention are suitable to make any multilayered article including a boat hull, such as a canoe hull, a liner for a truck receptacle, automobile parts such as fenders, and furniture.
Advantages of the present invention include quick, therefore, more efficient means of producing multilayered articles. Cost is reduced because production time is dramatically reduced, and the only apparatus required is a spraying apparatus. The mold does not have to be heated prior to spraying, and may be comparatively inexpensively and simply constructed.
~n important advantagc for thc cn~ironmcnt rc~ulting fro... u_ing f~st ~-ctting rc~in~ i~ that 1~E 60nt-~nant~
An important advantage for the environment resulting from using fast-setting resins is that less contaminants escape, e.g., isocyanate, due to a reduced timeduring which compositions are volatile.
An aspect of the present invention is the layered structure formed by the 5 method disclosed. The structure is composed of one or a plurality of layers, depending on the nature of the application o~ the structure. A suitable composition of the first layer of the structure includes a thermoset resin. A suitable composition of at least one of the inner layers of the suitable includes a foam, for example, a foam composed of water and resin. The resin is a thermoset resin. There is no size 10 limitation associated with an article produced by the methods of the present invention, although it is most suitable for relatively large articles, such are exemplified herein.
The advantages of the layered structure of the present invention include flexibility of construction and of composition of the layers. The layers may be thicker 15 or thinner in areas where a thicker or thinner thickness is advantageous, in contrast to what can be achieved using other methods, for example rotational molding or blow molding. If robotic spraying is used, layer thickness is controlled. Additives may be put in the layers such as pigment, and metal reinforcements. Another advantage is that when used for a molded article, the composition applied by the methods of the 20 present invention, has a "mold memory," rather than a sheet memory as in the methods of the art which heat sheets and mold them into forms. Thermoplastic type compositions are characterized by a tendency to revert to their original form from a subsequently imposed form, such as that imparted by the thermo-formed molding process. Therefore, articles of the present invention are more responsive to repairs 25 especially after being damaged, for example, by blows to the article.
.
The layers of the structure may be any thickness, but a preferred range is from .0508-1.016 mm (2-40 mil). Layers may be the same or different thicknesses when compared to each other. Layers of the same composition may be accumulated to increase the thickness of a particular composition layer, e.g., from to 1.016 mm to 5 50.8 mm (40 mil to 2 inches). The number of layers will be a function of the thickness of an individually sprayed layer, and the number of repetitions.
Detailed DescriPtion of the Preferred Embodiments Thermoset Resins Thermoset resins are suitable for the methods of the present invention if they 10 are capable of being applied to a solid support by spraying, and they have anelongation of at least 10 %. The resins are two-part liquid resins of polymers that chemically react very quickly to become solid. By a two part resin is meant a composition which is divided into two components which must be mixed in order for hardening to occur. By very quickly is meant in as little time as seconds. The exact 15 hardening time will vary with the specific composition.
In an illustrative embodiment, the resins comprise polyurea. In another embodiment, the resins comprise a hybrid polyurethane and polyester. A suitable composition is the EC Series 23, which is available from EniChem, Polyurethane Design Division,1448 V.F.W. Drive, Conyers, Georgia 30207. Characteristics of the 20 EC Series 23 are shown in Table 1. EC Resin System Series 23 is a 100% solid polyurea system. It has been used for reaction injection molding (RIM). For thatpurpose, key processing benefits are the adjustable gel time from 3 to 45 seconds, which was purported by the manufacturer to eliminate mold flowing problems.
"Fillers" are easy to process for enhanced properties; "optional internal molding 25 release" is available for optimizing cycle times.
The EC23 system enhances the quality of the molded part by minimizing sink marks and shrink. Also, paintability is said to be excellent using standard automotive paint and techniques.
TABLE 1: Characteristics of EC Series 23 PHYSICAL PROPERTIES:
EC EC
Specific Gravity 1.12 1.120 Thickness .125 .125 Tensile Strength atm 238.161 265.379 (3.5K) (3.9K) Elongation % 95 73 Flexural Modulus atm 5449.68 6804.6 (80K) (100K) Shore D 60D 65D
Notched Izod-lmpact 7 5 Linear Shrinkage 0.75 0.75 HeatSag-1 hr.@ 121.11C (250F) MOLDING CONDITIONS
ISO Temperature 32.22C 32.22C
(90F) (90F) Polyol Temperature 32.22C 32.22C
(90F) (90F) Mixing Pressure 136.092 atm 136.092 atm (2000 PSI) (2000PSI) Mix Ratio 1.14/1 PBW A/B 1 /1 PBW AB
Another resin suitable for use in the present invention is the EniChem series EC 242.
Characteristics of that series of resins are presented in Table 2. EC Resin Systems Series 242 is a high-modulus hybrid polyurea that was designed for high productivity RIM production. Gel times are adjustable from 5 to 45 seconds implemented by 30 catalyst changes. According to the manufacturer, EC 242 provides excellent green strength and good release characteristics from the mold. EC Series 242 has excellent impact strength with minimal heat sag up to 135C (275).
TABLE 2: Characteristics of EC Series 242 5PHYSICAL PROPERTIES:
EC EC
242-21 242-25 ASTM Method Density 68PCF 68PCF D 1622 Hardness, Shore D 72 75 D 2240 Tensile Strength 360.644 atm 401.471 atm D 412 (5300 PSI) (5900 PSI) Elongation @ Break 180% 140% D 412 Flexural Modulus @ 22C 10207 atm 15174.258 atm D 790 (150,000 PSI) (223,000 PSI) Heat Sag . 101.6mm "4" "overhang 1 hr. @ 121 C 3.3 mm 3.3 mm D 3769 1 hr. @ 121 C (.13 ins.) (.13 ins.) D 3759 Notched Izod Impact 10.36 Kg/M .8295 Kg/M
(75. ft./lbs.) (6 ft./lbs.) **Post Cured @ 121 C for one hour Spraying Means Any means for spraying a two-part thermoset resin on to a solid support so 25 that the resin forms a layer, is suitable for purposes of the present invention. A spray gun may be ordered from Tel 908 Gusmer, 1 Gusmer Drive, P.O. Box 110, Lakewood, New Jersey 08701 -0110. Apparatus for spraying include the gun claimedin FR 2520639; and the thermal spray gun of U.S. 4,999,225.
While the invention is susceptible to various modifications and alternative 30 forms, specific embodiments C~155~17 thereof are shown by way of examples. It should be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
5 EXAMPLE 1: Preparation of a Three-Layered Structure The first layer was composed of thermoset resin EC 491. It was sprayed on to the solid support using a spray gun and allowed to harden for one minute. A solid support was a fiberglass canoe mold.
The second layer was a foam layer produced by adding water to the non-10 isocyanate part of the resin system Part B. When the two parts are mixed, the waterreacts with the isocyanate in Part A to form C02. The more water that is added, the more C02 that is produced, and the more foaming action, or less density, results.
The second layer was sprayed on to the first and allowed to harden for two minutes.
The third layer was composed of the same resin used in the first layer. It was 15 sprayed onto the second layer and allowed to harden for 45 seconds.
The thickness of the first and third layers was about 1.27 mm (50 mil or .050 inches) .
The temperature at which the spraying was done was 22.22C (72).
EXAMPLE 2: Producing a Canoe The three layered structure of Example 1 is used to form the structure of the canoe .
The solid support used was a canoe-shaped mold. The moid that was used is a hand layed-up polyester fiberglass mold, the same type of mold that is used for a hand layed-up boat, such as a canoe or other fiberglass structure.
A mold is made using the same equipment and the same basic material as described in Example 1. This means a W094/14587 215 ~ 3 ~ 7 PCT~S93/1~03 ~ ,~ ,~ ,q Thc fir~t laycr w~s composcd of thcr~Ect rc~in Er 491. It was sprayed on to the solid support using a spray gun and allowed to harden for one minute. A solid support was a fiberglass canoe mold.
The second layer was a foam layer produced by add~ g water to the non-isocyanate part of the resin syste ~Part B. When the two parts are mixed, the water re ~ s with the isocyanate in Part A to form CO2. The ~ore water that is added, the more CO2 that is prod~ ed, and the more foaming action, or less density/ results. The second layer was sprayed on to the f~ st and allowed to harden for two minutes.
The third layer was compos ~ of the same resin used in the first layer. It was s ~ayed onto the second layer and allowed to harden for ~5 seconds.
The thicknecs of th~first and third layers was about 50 mil or .050 inche~
The temperatu~ at which the spraying was done was EXAMPLE 2: P~ ducing a Canoe The t~ ee layered structure of Example 1 is used to form t ~ structure of the canoe.
~ he solid support used was a canoe-shaped mold. The m~ d that was used is a hand layed-up polyester / iberglass mold, the same type of mold that is used for / a hand layed-up boat, such as a canoe or other fiberglass / structure.
/ A mold is made using the same equipment and the same ba~ic ~-t~rial aE dcscribcd in ~Y~rlc 1. Thie ~can~ a part can be duplicated by waxing the part, spraying the support as described in Example 1 (to create a mold), pulling the part from the mold, waxing the mold, spraying the mold again as in Example 1, to duplicate the part.
EXAMPLE 3: Manufacturing a Liner for a Truck Cavity A liner that fits snugly into the cavity of a truck is desirable to protect the basic truck finish from abrasion, for example, due to articles transported in the W094114587 215 ~ 31~ PCT~S93/1~03 cavity of a pick-up truck, and from the weather. Liners available in the art generally are composed of polyethylene, and must be attached to the truck with bolts and rivets. The attaching process itself, violates the integrity of the truck finish. Another disadvantage of the liners currently available, is that they are not readily removed.
Using the methods and compositions of the present invention, superior truck liners are produced that are resistant to weather and abrasion because of the strength and resistant surface properties that characterize thermoset polymers. In addition, because the polymer layers are sprayed directly on the truck cavity, no extra mold is needed. This reduces cost and improves fit of the liner to the truck cavity. If the interior of thetruck is waxed prior to spraying the first polymer layer, the liner may be readily removed by simply lifting it out.
Although the number and composition of the layers may vary depending on the nature of protection desired, the three layered structure of example 2 is a suitable structure for this purpose.
Claims (10)
1. A method for making a layered canoe, said method comprising:
(a) spraying a composition onto a solid support to form a layer, said composition a two-part thermoset resin comprising polyurea having an elongation of at least 10%; and (b) repeating step (a) as many times as required to form the layered canoe, wherein the solid support after a first solid support is the previously formed layer.
(a) spraying a composition onto a solid support to form a layer, said composition a two-part thermoset resin comprising polyurea having an elongation of at least 10%; and (b) repeating step (a) as many times as required to form the layered canoe, wherein the solid support after a first solid support is the previously formed layer.
2. A method for making a liner for a receptacle in a truck, said method comprising:
(a) spraying a composition onto a solid support to form a layer, said composition a two-part thermoset resin comprising polyurea having an elongation of at least 10%; and (b) repeating step a as many times as required to form the layered liner, wherein the solid support after a first solid support is the previously formed layer.
(a) spraying a composition onto a solid support to form a layer, said composition a two-part thermoset resin comprising polyurea having an elongation of at least 10%; and (b) repeating step a as many times as required to form the layered liner, wherein the solid support after a first solid support is the previously formed layer.
3. A layered canoe comprising a plurality of layers formed by spraying successive layers of a two-part thermoset resin having an elongation of at least 10% and comprising polyurea, onto a previously formed layer until all layers required for the structure are present.
4. A liner for a truck comprising a plurality of layers formed by spraying successive layers of a two-part thermoset resin having an elongation of at least 10% and comprising polyurea, onto a previously formed layer until all layers required for the structure are present.
5. A method for making a layered canoe, said method comprising:
(a) spraying a composition onto a first support to form a first layer, said composition a two-part thermoset resin comprising polyurea having an elongation of at least 10%, said layer being solid, and having a thickness in the range of 1 mil to 2 inches;
(b) repeating step (a) to form a second layer wherein the support after the first solid support is the layer formed in (a) and water is bubbled through the resin to form a foam layer having a thickness in the range of 1 mil to 2 inches;
(c) repeating step (a) to form a third, inner layer, wherein the support is the layer formed in step (b) said layer being solid and having a thickness in the range of 1 mil to 2 inches.
(a) spraying a composition onto a first support to form a first layer, said composition a two-part thermoset resin comprising polyurea having an elongation of at least 10%, said layer being solid, and having a thickness in the range of 1 mil to 2 inches;
(b) repeating step (a) to form a second layer wherein the support after the first solid support is the layer formed in (a) and water is bubbled through the resin to form a foam layer having a thickness in the range of 1 mil to 2 inches;
(c) repeating step (a) to form a third, inner layer, wherein the support is the layer formed in step (b) said layer being solid and having a thickness in the range of 1 mil to 2 inches.
6. A method for making a liner for a receptacle in a truck, said method comprising:
(a) spraying a composition onto a first support to form a first layer, said composition a two-part thermoset resin comprising polyurea having an elongation of at least 10%, said layer being solid, and having a thickness in the range of 1 mil to 2 inches;
(b) repeating step (a) to form a second layer wherein the support after the first solid support is the layer formed in (a) and water is bubbled through the resin to form a foam layer having a thickness in the range of 1 mil to 2 inches;
(c) repeating step (a) to form a third, inner layer, wherein the support is the layer formed in step (b) said layer being solid and having a thickness in the range of 1 mil to 2 inches.
(a) spraying a composition onto a first support to form a first layer, said composition a two-part thermoset resin comprising polyurea having an elongation of at least 10%, said layer being solid, and having a thickness in the range of 1 mil to 2 inches;
(b) repeating step (a) to form a second layer wherein the support after the first solid support is the layer formed in (a) and water is bubbled through the resin to form a foam layer having a thickness in the range of 1 mil to 2 inches;
(c) repeating step (a) to form a third, inner layer, wherein the support is the layer formed in step (b) said layer being solid and having a thickness in the range of 1 mil to 2 inches.
7. A layered canoe comprising a plurality of layers formed by spraying successive layers of a two-part thermoset resin having an elongation of at least 10% and comprising polyurea, onto a previously formed layer until all layers required for the structure are present, wherein the composition of the first and last layer is solid, and for layers intermediate between the first and last layers, foam layers alternate with solid layers.
8. The layered canoe of claim 7, wherein there are three layers, an inner, middle and outer layer, and wherein the inner and outer layer are solid, and the middle layer is a foam layer.
9. A liner for a truck comprising a plurality of layers formed by spraying successive layers of a two-part thermoset resin having an elongation of at least 10% and comprising polyurea, onto a previously formed layer until all layers required for the structure are present, wherein the composition of the first and last layer is solid, and for layers intermediate between the first and last layers, foam layers alternate with solid layers.
10. A canoe constructed from a resin, wherein the improvement comprises spraying multiple layers of a two part thermoset resin having an elongation of at least 10% and comprising polyurea, wherein the first layer is a solid layer sprayed on a solid support, a second layer is a foam layer sprayed on the first layer, and successive layers alternate between solid and foam layers, the final layer being a solid layer, and wherein all layers have a thickness of 1 mil to 2 inches.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US99551092A | 1992-12-21 | 1992-12-21 | |
| US07/995,510 | 1992-12-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2155317A1 true CA2155317A1 (en) | 1994-07-07 |
Family
ID=25541911
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2155317 Abandoned CA2155317A1 (en) | 1992-12-21 | 1993-12-21 | A layered article prepared by spraying a thermoset resin to form each layer |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0675791A1 (en) |
| CA (1) | CA2155317A1 (en) |
| WO (1) | WO1994014587A2 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19506255A1 (en) * | 1995-02-23 | 1996-08-29 | Bayer Ag | Sandwich structural element made of polyurethane and process for its production |
| US5595701A (en) * | 1995-05-12 | 1997-01-21 | The Goodyear Tire & Rubber Company | Process for making a polyurea backed product with a polyurethane skin |
| GB2342654A (en) * | 1998-07-29 | 2000-04-19 | Basf Corp | Sprayable polyurethane elastomer composition |
| DE10033260A1 (en) * | 2000-07-10 | 2002-02-21 | Bayer Ag | Impact-resistant sandwich structure element |
| CZ297138B6 (en) * | 2003-11-20 | 2006-09-13 | Interior accessory, particularly furniture or part thereof, and process of its manufacture | |
| US8158249B2 (en) | 2007-05-21 | 2012-04-17 | Featherlyte, Llc | Multi-layered foam furniture method and apparatus |
| US9460029B2 (en) | 2012-03-02 | 2016-10-04 | Microsoft Technology Licensing, Llc | Pressure sensitive keys |
| US9064654B2 (en) | 2012-03-02 | 2015-06-23 | Microsoft Technology Licensing, Llc | Method of manufacturing an input device |
| US20130300590A1 (en) | 2012-05-14 | 2013-11-14 | Paul Henry Dietz | Audio Feedback |
| US9759854B2 (en) | 2014-02-17 | 2017-09-12 | Microsoft Technology Licensing, Llc | Input device outer layer and backlighting |
| WO2016042028A1 (en) | 2014-09-19 | 2016-03-24 | Basf Se | Component which is at least partly made of a layer structure, and method for producing same |
| FR3026049B1 (en) | 2014-09-24 | 2018-01-05 | Societe Francaise D'assainissement - Sfa | STRUCTURE OF MULTILAYER COMPOSITE MATERIAL, ITS IMPLEMENTATION METHOD AND SANITARY ARTICLE PRODUCED THEREFOR |
| FR3026048B1 (en) * | 2014-09-24 | 2016-10-28 | Soc Francaise D'assainissement - Sfa | STRUCTURE OF MULTILAYER COMPOSITE MATERIAL, ITS IMPLEMENTATION METHOD AND SANITARY ARTICLE PRODUCED THEREFOR |
| NL2018902B1 (en) * | 2017-05-11 | 2018-11-15 | Cleopatra B V | Method for manufacturing a self-supporting product |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1374829A (en) * | 1972-07-14 | 1974-11-20 | Matec Holding | Manufacture of plastics parts |
| DE2240698A1 (en) * | 1972-08-18 | 1974-02-28 | Joachim Ruhnau | Pressure-less moulding foamed polyurethane - with glass fibre reinforce-ment |
| JPS59103716A (en) * | 1982-12-04 | 1984-06-15 | Toto Ltd | Manufacture of bath tub with pattern |
| US4891086A (en) * | 1987-04-16 | 1990-01-02 | Texaco Inc. | Strand coating method |
| DK260789D0 (en) * | 1989-05-29 | 1989-05-29 | Thermoform As | PROCEDURE FOR MANUFACTURING A LAMINATED ARTICLE WITH A COAT OF VACUUM-TERMOPLASTIC PLASTIC AND A PREPARED COAT OF CASTLE PLASTIC, AND BATCHES MADE IN EXERCISE OF THE PROCEDURE |
| US5266671A (en) * | 1989-09-25 | 1993-11-30 | Texaco Chemical Co. | Spray polyurea elastomers with abrasion resistance |
-
1993
- 1993-12-21 CA CA 2155317 patent/CA2155317A1/en not_active Abandoned
- 1993-12-21 EP EP94904856A patent/EP0675791A1/en not_active Withdrawn
- 1993-12-21 WO PCT/US1993/012303 patent/WO1994014587A2/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| WO1994014587A3 (en) | 1994-09-29 |
| EP0675791A1 (en) | 1995-10-11 |
| WO1994014587A2 (en) | 1994-07-07 |
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