JPS6012234B2 - Molded pulp product with plastic liner and method for manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to molded articles, such as food containers, which have a plastic liner on at least one side thereof, usually the food receiving side. When empty, it will not change even if exposed to temperatures of about 4000 F or higher for a short time, and if it is filled with food at room temperature or lower, it will not be damaged even if heated for about 48 minutes.

Prior to the present invention, various thermoplastic materials, such as polyester, have been bonded to molded, preformed bodies of fibrous material using heat and pressure.

This product is suitable as a moisture-proof container for food service such as plates and bowls.

However, it was known that such containers were not suitable for heating such as exposure to high temperatures for long periods of time. That is, when exposed to high temperatures, the plastic liner will melt or shrink and peel away from the molded pulp base, and the pulp itself will turn brown or turn black if exposed to such temperatures for an extended period of time. Typical conventional examples of such containers are as follows. U.S. Pat. No. 2,590,221 discloses applying polyethylene to a molded pulp body by heating the surface of the thermoplastic material to be bonded to the pulp at the melting point while maintaining the opposing surface at a temperature below the melting point. 1 shows a method of melting or gluing sheets of thermoplastic materials such as

U.S. Pat. No. 3,616,197 discloses a method for adhering a polypropylene membrane liner to a molded pulp board with an intermediate adhesive layer such as a polyamide ink or resin emulsion.

U.S. Pat. No. 3,657,044 describes a method of bonding a sheet of thermoplastic material such as polyester to a molded pulp body by pressing a thermoplastic material at a pressure higher than atmospheric pressure. It shows. US Pat. No. 3,697,36' discloses a method of melting or bonding a polyethylene membrane liner to a molded pulp plate with an intermediate layer of polyethylene that ensures adhesion to the molded pulp.

South Africa's Patent No. 73/2 describes a method of bonding a pre-extruded laminate film of polyethylene and polypropylene to a molded pulp body. A heatable container suitable for cooking food is by its own nature compressed or folded and glued from a piece of flat vapor board with a coating of amorphous polyethylene terephthalate glued to at least one side of the board. Molded.

However, such containers have a number of disadvantages, such as the expense of compressing and bending and gluing the container from a flat plate, and the coating tearing at the fold line.

Such containers are usually not as durable or desirable as molded containers. Also, compression-formed or folded containers naturally have creases or gaps in the corners, and these creases or gaps are completely undesirable in a container such as a pancake. Folds, etc. will damage the plastic seal. Typical examples of prior art patents for such containers are as follows. US Patent No. 3924013
The issue shows that it forms a food container that can be heated from the non -brown laminated laminated, which is directly pulled out as a heated resin that is adhered to the upper surface of almost non -crystal polyethylene telephate, which is adhered to the top surface. .

U.S. Pat. No. 4,147,836 discloses the application of a paperboard corona discharge to form a heatable food container from a polyethylene terephthalate coated laminate; No adhesive effect occurs.

Thus, the drawback that cannot be solved by the follow-up technology is that it is formed three-dimensionally without folds or curves, and the plastic liner may melt when exposed to high temperatures for a long time in a microwave oven, etc. It also does not provide an inexpensive, disposable container that can hold food products without shrinkage and peeling from the formed base, brown discoloration of the base, or any other deleterious effects on the container or food product. That's true. The present invention comprises a base having a preformed shape molded with fiber pulp having a liner directly adhered to at least one formed portion on at least one side of the base, the liner being exposed to a temperature of about 4000F. It is made of unlined polyethylene terephthalate that shrinks and peels from the base even when exposed to heat.

The method of the present invention involves incubating a base having a preformed shape molded with fiber pulp to rapidly preheat a thin film of mostly amorphous, non-oriented polyethylene terephthalate above the temperature at which crystallization begins; The heated thin film is rapidly pressed into contact with at least one feature on at least one side of the heated base, while the thin film spreads into direct contact with the base having the shaped portion, and the thin film is pressed onto the base. the base and liner are brought into direct contact to form a continuous, unitary liner, and finally the base and liner are cooled to room temperature. The present invention describes firstly a pre-molded pulp base, secondly a polyethylene terephthalate film, thirdly a method of adhering the film to a base, and fourthly a molded pulp product using the resulting polyester as a liner. It can be understood in detail depending on what you do.

First, the pre-molded pulp base is
The shape and dimensions of the product of the present invention are determined, and the shape and dimensions depend on the object for which the product is used.

The base can be obtained by any one of several known pulp forming techniques. For high quality products such as heatable containers for commercial food products according to embodiments of the present invention, molded pulp bases are obtained by a precision molding process known as die drying or closed drying process.

Precision molded pulp products are produced by molding the fiber pulp into approximately its final shape from an aqueous slurry using an open-face suction mold covered with a screen, and then transferring the moisture to a pair of heated molds. It is obtained by drying under the great pressure created by combining the two. This may be done, for example, by an apparatus or method such as that described in US Pat. No. 2,183,86. Precision molded pulp products are dense, strong sheets with extremely smooth iron-on surfaces. These precision molded pulp products were manufactured and sold in the form of disposable boards, balls, etc. under the trademark CmNET by Keith Fiber Company of Waterville Mine in the United States.
Molded pulp products based on pulp obtained by precision molding processes and other known free-drying, open-drying processes may likewise be used in the practice of this invention. The free-drying method involves molding the fiber pulp from an aqueous slurry into a roughly final mold in an open-face suction mold covered with a screen, and then moving it slowly on a conveyor into a heated drying oven to remove moisture. It has a drying process. Such molded pulp products are loose, firm, flexible, and have an irregular fiber feel and shape. When a free-dried molded pulp base is used in the practice of this invention, the flat fiber surface is pressed against the pulp base as the membrane is bonded at slightly lower temperatures and pressures, and the membrane is not pressed against the pulp base. It is necessary to have sufficient strength to prevent pinholes from forming on the fiber surface. Molded pulp bases obtained by other known pulp molding methods are similarly useful in the practice of this invention.

This includes molded pulp products that are first molded by a free-drying process and then pressed by the means described in U.S. Pat. The molded pulp product is placed in a shape that prevents open-face distortion on a moving conveyor and prevents it from deforming from distortion during the drying process as described in U.S. Pat. No. 3,185,37. According to an embodiment of the invention, the pulp is approximately 10
0% bleached craft wood fiber.

When this material is exposed to a temperature of approximately 4000F for 15 minutes,
It is preferable because it does not change color from desirable white to yellow to undesirable brown or dark brown. When food or other items at or below room temperature are placed in close proximity to provide a heat sink effect, this material will heat up to about 450 degrees Fahrenheit for 48 minutes.
It can be subjected to temperatures above 0F but will not turn brown. However, when the product is not exposed to the above-mentioned times and temperatures, other shapes and qualities of fiber pulp may be used without departing from the objectives of the present invention.

Regardless of the molding method, shape, and quality used to obtain the base, the base may be either a fluorocarbon oil waterproof sizing or a synthetic water-soluble water-repellent sizing (reactivesynth), which does not interfere in any way during the bonding process described below.
ticwa r sizing) or other known sizing.

The base is molded into a substantially completed three-dimensional shape, whether the molded pulp is precision molded or by one of several free drying methods.

Its shape can be shallow or deep, depending on the intended use, as seen in polyester-backed products. In either case, the shape has a horizontal wall part and a sloped wall part,
There are no vertical walls. A plurality of empty bases, and a final lining manufactured from these bases, as they have no vertical wall sections other than 4. small vertical shoulders or protrusions for stacking to avoid clutter. The product is easily
They can be stacked on top of each other for inexpensive shipping or storage. Furthermore, the molded pulp base and the lined product made from the base have a generally uniform thickness, such that any feature projecting outwardly from one side corresponds to a corresponding recess on the other side. . Second, the polyethylene terephthalate that forms the molded pulp-based liner is a thin film of non-crystalline, non-oriented polyethylene terephthalate that can be thermally deformed and has a relatively high molecular weight.

Although the polyethylene terephthalate described above can be used in plate form with a thickness of about 7.0 mils or more, thin films of about 7.0 mils or less are preferred in the present invention. This material is sold under the brand name PETRA by Allied Chemical Corporation, New Jersey, Morristown, USA, and many of its properties described below are described in German Patent No. 2,125,978. .

According to an embodiment of the invention, such polyethylene terephthalate film is adhered to a smooth-sided base obtained by precision molding and has a thickness of between about 0.5 and 2.0 mils. is preferred and the most satisfactory thickness is 1.0 mil, or between 0.9 and 1.25 mil.

having a plurality of deep, closely spaced pockets or recesses;
Alternatively, if the invention is carried out to obtain vessels of rather complex and deep shape, such as baking dishes, with a molded pulp base obtained by a fried drying method on a relatively rough surface, it is well known that As such, thicker films are used to expand against or protect against undesirable pinholes. Polyethylene terephthalate membranes according to the present invention thermally deform and expand to conform to shallowly formed molded pulp bases at temperatures of about 17 degrees Fahrenheit and above.

This material becomes liquid at temperatures from about 48 degrees Fahrenheit to about 490 degrees Fahrenheit or higher. This film is mostly amorphous and is actually transparent, about 5%
It has the following crystallinity.

However, above the lowest thermoforming temperature or below the melting temperature the material crystallizes spontaneously. For example, a film about 1 mil thick will mostly crystallize when held at a temperature of about 25F to about 4000F for 2 to 15 seconds. When held in the crystallization temperature range for such a period of time, the film changes from almost transparent to white and translucent, clearly crystallizing and crumbling, and does not readily adhere to mold pulp at temperatures below about 4000F. It should be noted, however, that exposing the film to crystallization temperatures for less than a few seconds does not result in an undesirable increase in crystallization, which has an adverse effect on either film formation or adhesion properties. This is believed to be the result of many improvements made by the present invention, as detailed below. The polyethylene terephthalate membrane according to the invention is almost non-directional, meaning that the membrane does not expand metered during its manufacture.

The membrane is made of polyethylene terephthalate resin at approximately 5100F.
by extruding through a slit die at a temperature between about 60F and about 5400F and then cooling the flat thin film on polish rolls at a temperature between about 6F and about 2000F. Some longitudinal texture occurs during extrusion of the resin into a film, but the extent is minimal due to extrusion through a slit die and cooling on polish rolls. The use of polyethylene terephthalate having a relatively high molecular weight is believed to be important, although not a major feature of the invention.

Actually about 15,000 or more, i.e. 15 000 to 3
Materials with molecular weights in the range of 0.000 are useful;
I found it to be favorable. This is in contrast to polyethylene terephthalate, which has a relatively low molecular weight, such that the molecular weight does not exceed about 10,000. However, about 12,0
Molecular weights lower than 0.00 are quite shallow in shape and are suitable for the manufacture of containers or other products where minimal expansion of the membrane prior to adhesion is desired, and where the product is used for long periods of time where adhesion between liner and base is minimal.・It is still effective when mechanical adhesion is sufficient. Third, the method of adhering the membrane to the base involves incubating the preformed base obtained by the above-mentioned means, rapidly preheating the polyethylene terephthalate membrane with the above-mentioned properties, and then attaching the pre-heated membrane to the base. A liner is formed on the base by rapid heat pressing into contact with the heated surface of the base, and the heat pressing is applied at a predetermined temperature to ensure that the membrane extends into direct contact with the formed base. Depending on the nature of the katsumeji, it can be bonded directly to the base to form a uniform, integral liner on the base, and finally the base and liner are allowed to cool at room temperature. More specifically, with reference to FIG. 5, a preferred method of the present invention is carried out as follows.
A pulp base 10, which has been precisely molded in advance, is placed in a mold 12 with an open top. This mold is sized to support the entire base by supporting the lower surface not covered by the polyester liner. The mold 12 has a suction hole 14 connected to a vacuum source (not shown) so that vacuum is supplied through the base during the bonding process.

The preferred degree of vacuum is about 20 inches in mercury, with low vacuum being suitable for shallow shapes and thin films, and high vacuum being suitable for deep shapes and thick films. Type 12 is about 3000F and about 6000F
It is maintained in a heating device (not shown) in a temperature range between F and F. An appropriate temperature is selected within this range, and the molded pulp base is preheated for a suitable period of time before the deposition process so that the surface receiving the film is about 30 degrees F and about 37 degrees F'. Ru. As a result, the corresponding surface in contact with the heated mold reaches a high temperature in a short time. When the molded pulp base is relatively thick and has a relatively complex and deep shape, preheating to a high temperature is necessary, whereas when the base is thin and has a relatively simple and shallow shape, minimal adhesion is required. If it is OK,
Child heat should be at the lowest temperature of the range. In any case, the base is preheated so that the surface to which the membrane will adhere is at the desired temperature, which may be as simple as holding the base in a heated mold for a short time. A membrane 16 of polyethylene terephthalate is also preheated and placed in close contact with the exposed surface of the base 10.

The means for positioning the membrane within the mold is not an essential feature of the invention, as a variety of methods may be used. Since the membrane should heat up quickly and be pressed quickly against the base,
Preferably, the membrane is placed on the base prior to or at least during preheating. The membrane is preheated by any means to above room temperature, above both the temperature at which thermal distortion occurs and the temperature at which crystallization begins in a relatively short period of time.

According to a preferred method, the membrane 6 is in contact with a plate 18 coated with a material such as Teflon and the membrane 16 is in contact with a plate 18 coated with a material such as Teflon.
is made so that it does not stick to the plate 18. Plate 18 is maintained at a temperature of about 3250F to about 4000F by suitable heating equipment (not shown), with temperatures within this range being selected depending on the thickness of the membrane and its molecular weight. about 7
．． Thick membranes, greater than 0 mil, require the plate 18 to be maintained at elevated temperatures within the aforementioned range, or the membrane is in contact with the plate for a relatively long period of time, whereas thinner membranes, approximately 1 mil thick, have lower temperatures. By contacting the plate at a temperature maintained, the required bonding temperature is rapidly established. The membrane undergoes rapid incubation during which at least the polyethylene terephthalate crystallizes.

For example, for a membrane having a thickness of about 0.5 to 2.0 mils, the membrane is preheated from room temperature to bonding temperature in no more than about 2 seconds. Once the membrane has been preheated to the desired temperature, a suitably preheated base is heated, and a vacuum is rapidly applied to the base, suctioning the membrane and bringing it into contact with the surface of the base to be coated. The membrane spreads out and becomes thinner in direct contact with the base, extending according to the shape and depth of the base.

Upon continuous application of vacuum, the pus by its nature adheres directly to the exposed surface of the pulp base molded to form an integral liner with the base. If desired, and completely optionally, a membrane may be applied to either side of the base, such as the edge or underside of the molded pulp base by the means described in the aforementioned U.S. Pat. No. 3,657,044. It gets sucked in.

Similarly, the pressing process that brings the membrane into contact with the base may not be a new feature based on the above, but it is possible to use a vacuum to press the membrane with a movable die against the edge or collar of the base or other parts. In place of or in addition to pressure, it includes pressure above atmospheric pressure or mechanical pressure. Similarly, the membrane only needs to be pressed against a portion of one side of the base. For example, if the base includes a formed bottom container with a pivotally connected closable cover part, only the inside of the bottom container need be lined with plastic. Also, either the base or the membrane, or both, may be printed for decorative, informational, and other purposes.
The concept of the invention is not disturbed if the printing is intermediate between the base and the membrane or if the medium of printing has adhesive properties. The pressing stroke of the present invention is held for a few seconds or less to physically bond the membrane and base.

When the base and membrane are preheated as described above and the membrane is pressed very firmly against the base in a vacuum to within about 20 inches of mercury, "the mechanical adhesion between the plastic and the pulp is approximately A membrane of polyethylene terephthalate approximately 1.0 mil thick is rapidly preheated and pressed onto the preheated base in less than approximately 1 second. If a pressure greater than atmospheric pressure is applied, the time required for proper bonding will be shorter, which is extremely important for mass production techniques.

The base and liner are then cooled to room temperature.

A preferred method of cooling the base and liner is to remove the lined base from the heated vacuum mold 12 and then allow the product to cool slowly to room temperature. After removal from the heated mold 12, residual heat in the molded pulp base portion of the product dissipates slowly over at least a few minutes, depending on the size of the article, and the product is immediately stacked for cooling and bonded. temperature to room temperature. Excess film or molded pulp, such as at the edges of the product or around the holes in the product, is scraped off by known means during or after the gluing or cooling process.

Finally, a final thermal annealing step is performed to crystallize the liner and improve its intended use properties. This may be done, for example, by exposing the finished product to a temperature within the range of about 2500F to about 4000F for several minutes or more. Fourth, as shown in FIG. 4, the polyester-backed molded pulp article 20 of the present invention has a preformed shaped base 10 of fibrous pulp.

This may be done with or without one or more sizings, and at least a liner 22 is bonded directly to the molded portion on at least one side of the base, as shown in FIG. Liner 22 is substantially moisture impermeable and is comprised of polyethylene terephthalate which does not shrink or peel from molded base 10 when exposed to temperatures of about 4000F. As mentioned initially in connection with the detailed description of the preformed base, the base of the preferred embodiment of the present invention involves molding the fibrous pulp into substantially its final shape and then placing the pulp in a pair of heated molds. It is obtained by drying under pressure applied by

The pulp is approximately 100% bleached kraft wood fibers, and exposure to temperatures of about 40 pF for 18 minutes eliminates the undesirable brown color. Also, as mentioned above, it has been found that the polyester phthalates of the present invention, if peeled from the base, do not readily adhere to molded pulp at temperatures below about 4000F.

This is because the liner has a crystallinity of at least about 8% and therefore does not have the adhesion to mold pulp that the initial membrane has. However, the strong bond initially obtained by the method described above is adhesive 1.
It is not affected by the Representative products according to the invention are shown in FIGS. 1 and 2.

FIG. 1 is a relatively simple perspective view of a shallow food service container with a horizontal base portion 32, a horizontal rim portion 34, a slanted side wall portion 36, and a mirror. It has an oblique section lip portion 38, but has almost no vertical portion. FIG. 2 is a perspective view of a relatively complex, deep-shaped, lightly toasted bread container 40, with a horizontal base portion 42;
It is formed by a horizontal upper connecting portion 44, a relatively deep portion with large slopes forming a set of closely spaced pockets 46, and almost no vertical portions.

In either case, the container according to the invention has a three-dimensional shape without vertical walls, as shown schematically in FIG. can be stacked concisely for this purpose.

Vertical walls 52 are provided to form a shoulder for easy removal of empty containers from the stack. There are approximately 40 products such as bakeable food containers according to embodiments of the present invention.
It can be exposed to temperatures of 00F and the liner will not melt or shrink away from the base. Such products can be held at temperatures of about 4000F for 15 minutes without the base turning brown. However, if the base is exposed to such high temperatures for a long time of 15 minutes or more, it will turn brown and eventually burn to black. In practical use, the product according to the invention can withstand high temperatures for long periods of time when food products etc. are heated within the container.

For example, the bread baking container shown in Figure 2, which has butter for baking in its pocket, has 4 strips of bread, 4
There is no delamination of the liner or brown discoloration of the pulp when exposed to temperatures of 1,000F. This is because the cold butter is first warmed and then heated, so the container itself has a heat lowering effect, so the container itself does not reach a high temperature of about 4000F in about 15 minutes. However, at the end of the fourth batch, the edge of the container farthest from the pocket turns yellow. The food service container shown in Figure 1 containing frozen meat was installed in the same machine for the purpose of warming the meat without further processing and without peeling of the liner or browning of the pulp. About 45 minutes
Exposure to high temperatures of 00F.

The temperature and time will depend on the size of the container, particularly the size and shape of the food being heated within the container, as well as the initial temperature of the container and its contents when exposed to such high temperatures. Additionally, the parameters of the intended use will depend on the conditions in which the heat is applied to the container and its contents. Conventional household electric ovens and commercial ovens are heated differently. Both ovens heat the container and the contents, but microwave ovens directly heat only the contents, while the container heats the contents. Therefore, it is a length that is heated and is not heated by microwaves. As discussed below, the heatable food container product according to the invention has many advantages over, for example, aluminum.

The containers of the present invention, which are not made of aluminum, are microwave safe, so the containers can be used in both microwaves and heating ovens. The products of the present invention require significantly less energy to manufacture than aluminum containers and can be used repeatedly. - When the product according to the invention is heated in actual use, the crystallinity of the polyethylene terephthalate liner increases and the pulp base is exposed to high temperatures for a long time and loses some of its original properties, resulting in shrinkage and exfoliation. There's nothing to do.

If this is true, then the properties of the product of the invention change when heated during use, but the heat rather changes the properties of both the pulp and the polyester to meet the requirements of food containers that can be heated. obtain.

[Brief explanation of the drawing]

1 is a perspective view of a relatively simple and shallowly formed food service container according to the present invention; FIG. 2 is a perspective view of a relatively complex and deeply formed baking container according to the present invention; FIG. Partial cross-section showing a number of representative empty containers stacked one on top of the other for storage; FIG. 4 shows a molded pulp base with a polyester liner adhered to its top surface in its own right; FIG. 5 is a partially enlarged cross-sectional view for clarity, and FIG. FIG. 3 is a schematic cross-sectional view. 10...base, 12...mold, 22...liner, 32
...Horizontal wall, 36... Slanted wall. 3. ．．・ Washio Ku・

Claims (1)

[Claims] 1. A product formed in three dimensions so that it can be stacked on top of each other so that it has horizontal and inclined walls but no vertical walls, and the product is an open-face suction type and is made of aqueous slurry. a pre-formed base obtained by molding a fiber pulp into a finished shape; and a moisture-impermeable liner adhered directly to at least one formed portion of at least one side of the base. The liner is approximately 400°
A molded pulp product having a plastic liner made of polyethylene terephthalate formed from a substantially amorphous non-directional film that does not shrink and peel off from the formed base even when exposed to temperatures of F. 2. The preformed base is obtained by molding the fibrous pulp into substantially its final shape and then drying the pulp under pressure created by bringing together a pair of heated molds. A molded pulp product having a plastic liner as described in Section 1. 3 The fiber pulp into which the base is molded is approximately 400°F.
A molded pulp product having a plastic liner according to claim 1 which does not turn undesirably brown when exposed to temperatures of 15 minutes. 4. A molded pulp product having a plastic liner according to claim 1, wherein the pulp is substantially 100% bleached kraft wood fiber. 5 The pulp is either fluorocarbon oil waterproof sizing or artificial water-soluble water repellent (reactive synthetic
A molded pulp product having a plastic liner according to claim 1 which is treated with ticwater repellant sizing. 6 The polyethylene terephthalate liner is approximately 15,
A molded pulp product having a plastic liner according to claim 1 having a molecular weight of 0,000 or more. 7. A molded pulp product having a plastic liner according to claim 1, wherein the polyethylene terephthalate liner does not readily adhere to the molded pulp at temperatures below about 400°F. 8. A molded pulp product having a plastic liner according to claim 1, wherein the polyethylene terephthalate liner has a crystallinity of at least about 8%. 9. preheating the preformed base obtained by molding the fiber pulp from the aqueous slurry in an open-face suction mold to the final shape with horizontal and inclined walls but no vertical walls; Preheating the polyester membrane and forming the preheated base so that the membrane is stretched into direct contact with the formed base and bonded directly to the base to form a uniform and integral liner on the base. pressing a preheated membrane into contact with at least one formed portion of at least one surface, the polyester membrane being substantially amorphous and non-oriented polyethylene terephthalate; The polyester film is preheated to a thermal deformation temperature within the range of substantial crystallization, and then the polyester film contacts the base while still being substantially amorphous, i.e., before crystallizing and no longer adhering to the base. The liner is rapidly pressed to bond and is characterized by the fact that, after the bonded product has cooled to room temperature, the liner does not shrink away from the formed base even when exposed to temperatures of approximately 400 degrees Fahrenheit. A method of manufacturing a molded pulp product having a plastic liner. 10 The membrane has a thickness of about 2.0 mm or less and an angle of about 250°
The membrane is preheated to a heat deforming temperature within a thermal range of approximately 400°F, and when this temperature is reached, the film is rapidly contacted and adhered to the base within about 2 seconds before reaching the temperature that causes heat deformation. A method for manufacturing a molded pulp product having a plastic liner according to claim 9, characterized in that the molded pulp product is pressed. 11 The base is made by molding approximately 100% bleached kraft wood pulp fiber from an aqueous slurry in an open-face suction mold, and then drying it under pressure created by fitting a pair of heated molds. A method for manufacturing a molded pulp product having a plastic liner according to claim 10 obtained by the method. 12 The initial film of polyethylene terephthalate is approximately 5%
10. A method of making a molded pulp product having a plastic liner as claimed in claim 9, wherein the liner is amorphous and adhered to the molded pulp base, the crystallinity of the liner being increased by at least about 8%. 13 Polyethylene terephthalate liner is approximately 40
10. A method of making a molded pulp article having a plastic liner as claimed in claim 9 which does not readily adhere to molded pulp at temperatures below 0 DEG F. 14. A method of manufacturing a molded pulp product having a plastic liner according to claim 9, wherein the polyethylene terephthalate has a molecular weight of about 15,000 or more. 15 The initial film of polyethylene terephthalate was approximately 17
Heat deforms at temperatures of 0°F or above, approximately 250°
A mold having a plastic liner according to claim 9 which crystallizes when held at a temperature between about 400° F. and about 400° F. for more than a few seconds and melts at a temperature from about 480° F. to about 490° F. or more. Method of manufacturing pulp products.