JPS6228363A - Heat-resistant paper vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat-resistant paper container. Or related to heat-resistant containers that can be rolled up 0 Prior Art and Technical Problems of the Invention Tray-shaped paper containers are used as containers that can be easily filled with contents such as food, but in recent years, they have been used in ovens, electronic With the spread of microwave ovens, open toasters, etc., cooked or uncooked foods are sold in tray-shaped containers, and when eaten, the containers are placed in the heating device mentioned above.
It is desired to develop a container that can be heated or packed. Although paper containers are cheap, they lack heat resistance.
It easily ignites or carbonizes, but even if it does not, its strength is significantly reduced by heating.

As this tray-shaped container, a tray-shaped container made of a laminate made of paper and a film of polyethylene terephthalate or poly-4-methylpentene-1 is already known, but in the open toaster mentioned above, etc.
Since the temperature reaches as high as 0 DC, the resin film melts and cannot function as a container at all.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a heat-resistant paper container that eliminates the drawbacks of the conventional paper containers described above.

Another object of the present invention is to provide a heat-resistant paper container that can be filled with contents and placed in a heater such as an oven, a microwave oven, or a toaster oven for heating or cooking. It is on offer.

Still another object of the present invention is to provide a heat-resistant paper container that stably maintains a predetermined container shape and required strength not only before heating but also after heating to a high temperature.

Structure of the Invention According to the present invention, a paper substrate having an elongation of 1.8 inches or more in the longitudinal and lateral directions, fibers provided on both sides of the paper substrate via an adhesive layer, and an inorganic filler that also serves as a flame retardant are provided. Provided is a heat-resistant paper container characterized in that it is formed by press-molding a laminate made of heat-resistant synthetic paper and a heat-resistant synthetic paper into the shape of a seamless container with a bottom.

Effects of the Invention The present invention consists of a paper substrate having an elongation of 1.8 inches or more in the longitudinal and lateral directions, and a heat-resistant synthetic paper containing fibers and an inorganic filler that also serves as a flame retardant, which are laminated together with an adhesive. By forming the container into a body shape, it is possible to press-form it into a tray or cup without causing breakage. This is based on the knowledge that it is maintained stably.

Synthetic paper containing fibers and flame retardants is known as so-called flame-retardant paper or non-combustible paper, but this paper has extremely low elongation and is difficult to use for containers. When press-molded into the shape of a tray or the like, there is a drawback that breakage occurs during molding. According to the present invention, by making this synthetic paper and paper with high elongation into a structure in which the paper substrate is sandwiched with the synthetic paper, it is possible to press-form into a container shape, and even after heating, the desired shape can be achieved. The shape and strength of the container can be obtained.

Press forming is performed by causing plastic flow in the sheet between a male mold called a punch and a female mold called a die, but in this case, stress is concentrated in a part of the sheet, and in the synthetic paper making process, this stress This causes rupture. The paper substrate used in the present invention effectively acts as a stress carrier during this molding. Furthermore, when the cross section of the laminate used in the present invention was observed after heating, it was found that the central paper substrate was carbonized. From this, in the container after heating,
It will be appreciated that the shape retention and mechanical strength of the container is due to the synthetic papermaking present on both sides of the paper substrate.

Furthermore, even after being heated in an oven, etc., flame-retardant or non-combustible synthetic paper is present on both sides of the paper substrate, so the carbonized layer is hidden by these synthetic papers, resulting in good appearance characteristics and commercial value. is maintained.

Preferred Embodiment of the Invention In FIG. 1 showing the cross-sectional structure of the laminate used in the present invention, synthetic papers 4 and 5 are bonded to both surfaces of a paper substrate 1 via an adhesive layer 2.6. ing.

In FIG. 2, which shows an example of the container of the present invention, this container consists of a flat bottom part 6, a body part 7 seamlessly connected to the bottom part, and a flat seven-rank part 8 connected to the upper end of the body part.

The paper substrate 1 has the following characteristics to enable press forming of the laminate:
Both longitudinal and axial elongation must be 1.8% or more. Such paper can be obtained by manufacturing paper by increasing the amount of long-fiber pulp, such as softwood pulp, among various pulps. The basis weight of the paper substrate is generally 100 to 5
005'/i, preferably in the range of 150 to 35 (1/m').

As the heat-resistant synthetic paper 4, 5, any material can be used as long as it contains fibers and a flame retardant and an inorganic filler. Wood bulbs are common as fibers, but
Inorganic fibers are also used to increase strength and heat resistance. As the inorganic fiber, glass R#, rock wool, slag wool, asbestos, ceramic fiber, etc. are used, but glass fiber is preferred. As a flame retardant and filler,
Aluminum hydroxide is most suitable, but magnesium hydroxide, calcium aluminate, dawsonite, etc. are also used. These flame retardant-cum-fillers contain water of crystallization and impart flame retardancy by releasing crystal water near the combustion start temperature of paper, etc. It imparts texture, etc. Of course, in the present invention, it is equally possible to use inorganic additives which themselves have a flame retardant effect (-2), such as silica, talc, clay, calcium carbonate, etc.

An inorganic binder, an organic resin binder, or the like may be added in order to improve paper formability or to bond or fix fibers to each other. Furthermore, an inorganic or organic sizing agent may be included for the purpose of adjusting (reducing) the water permeability of the synthetic paper.

In the present invention, the inorganic fiber is D to 50 per synthetic paper making.
It is desirable that the flame retardant/filler contains 1 to 60% by weight, especially 5 to 50% by weight.
It is particularly desirable that the content be 20 to 50% by weight.

Suitable examples of synthetic papermaking compositions include, but are not limited to, the following:

Inorganic fiber D to 50% Flame retardant/filler 10 to 60% Pulp fiber 10 to 60% Organic resin binder 0 to 10% Sizing agent O to 5% The above-mentioned papermaking composition is charged into a beating machine to obtain an aqueous The dispersion is made into paper using a known paper machine or the like.

Synthetic papermaking tsubo thso to 600y/d, especially 100y/d
~20C1/rr? The synthetic papers provided on both sides of the paper substrate may be the same or different. For example, the synthetic paper that forms the inner surface of the container can be provided with a coating layer or an impregnated layer that prevents liquid from permeating. Such a layer may be a paint coat layer or a film layer of a heat resistant resin such as polyimide, polyimide imidasovirolone, wholly aromatic polyamide, wholly aromatic polyester, epoxy-phenolic resin, etc. It may also be a water-repellent layer made of organosiloxanes, organic titanates, etc. Furthermore, it may be an inorganic coating layer made of silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, etc. alone or in combination. Good too.

Adhesives for bonding the paper substrate and synthetic paper include urethane adhesives, epoxy adhesives) a, acetic acid, emulsion adhesives such as vinyl resin, acrylic resin, vinyl chloride mIIW, and synthetic rubber. Agent 1, l-' IJ vinyl alcohol, carboxymethyl cellulose MTYW! 1
*'fB adhesive can be used.

The laminate can be easily formed into a container by a press molding method known per se, for example, using a combination of a punch and a die. According to the present invention, by using the above-mentioned laminate, it is a remarkable advantage that press molding from a tray with a shallow draw to a cup-shaped container with a deep draw can be easily performed.

The invention is illustrated by the following example.

Example 1゜Elongation 6.0% in length, 7.0% in width, tsubo t22o3/rr?
So, the fibers stretch on both sides of the paper substrate made only of wood pulp, have a length of 14%, a width of 1.4%, and a basis weight of 12OS'/rr?
The composition is 10% glass fiber, 48% wood pulp fiber,
Noncombustible paper containing 40% aluminum hydroxide and 2% binder was laminated using a styrene-acrylate copolymer adhesive.

The laminate obtained by smelting is press-molded into a vertical 18Cr
A rectangular tray with r1, width 10 rrn, and i 2 crn was molded. Store in the refrigerator in this square tray 1. Add 6 skewers of salted yakitori and heat in a gas oven over medium heat for 6 minutes. After heating, the yakitori was taken out of the oven and when tasted, it had an appropriate temperature and a medium flavor. At this time, the surface of the square tray was not burnt and no discoloration was observed. Furthermore, the surface temperature of the square tray during heating was measured and found to be 250C.

Example 2 A polyimide film with a thickness of 10 μm was laminated on one surface of the six-layer laminate of noncombustible paper/paper substrate/noncombustible paper of Example 1 using a urethane adhesive. A square tray of the same size as in Example 1 was molded from the obtained four-layer laminate by press molding so that the polyimide film was on the inner surface. Three skewers of yakitori with sauce that had been stored in the refrigerator on this square tray.
I put it in a toaster oven and heated it for 4 minutes. After heating, remove the yakitori from the oven (2.
When I tasted the yakitori, it was the right temperature and delicious. At this time, no discoloration of the surface of the square tray was observed. Also,
During heating, measure the surface temperature of the square tray (at 7:27
It was 0″C.

Example 6゜41 whose inner surface was coated with a 20 μm polyethylene terephthalate film instead of the three-layer laminated layer in Example 1.
When a similar test was conducted using the if laminate, no discoloration V'i was observed on the surface of the square tray.

Example 4 The inner surface of the rectangular tray obtained in Example 1 was coated with a coating agent based on silicon oxide and titanium oxide by spraying. Put macaroni gratin in this square tray,
Heat in a gas oven over medium heat for 10 minutes. After heating, the tray was taken out of the oven and the macaroni gratin was tasted. The center of the macaroni gratin had been sufficiently heated and was delicious, and no discoloration was observed on the surface of the square tray.

-J, When the same square tray containing macaroni gratin was placed in a microwave oven and heated, heating was completed in 5 minutes.

In this way, this square container has good microwave penetration,
It was possible to heat efficiently in a microwave oven.

Comparative Example 1゜A paper with the same composition as the paper used as the substrate of the laminate instead of the 6-layer laminate in Example 1, but with a basis weight of 400 r/rr? When a similar test was conducted using a low phosphorescent material, the surface of the square tray turned brown after heating (7).Also, a decrease in paper strength was observed, and it was easily removed by applying force by hand. The wall of the square tray broke.

Example 5: Elongation length: 6.5%, width: 75%, basis weight: 2509/rrl,
On both sides of the paper substrate, which consists only of wood pulp as the fiber,
Elongation 1.2%, width 1.2 inches, basis weight 10C1/yr? Noncombustible paper with a composition of 50% glass fiber, 62% aluminum hydroxide, 15% colloidal silica, and 3% organic binder was laminated using a styrene-acrylic copolymer adhesive.

The obtained laminate is press-molded into a diameter of 15 m.
, mold a master tray with a depth of 2 cm 1. Ta.

Next, a silicon oxide film was coated on the inner surface of this master tray by an ion blating method (7).

This prototype tray was filled with beef stew and heated in a gas oven over medium heat for 10 minutes. After heating, the beef stew was at an appropriate temperature and delicious. The surface was not burnt and no discoloration was observed.

Example 6゜The same test as in Example 3 was conducted using a noncombustible paper with a composition of 58% wood-kolp fiber, 40% aluminum hydroxide, and 20% binder as the nonflammable paper in Example 3. No discoloration was observed on the surface of the mold tray.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a laminate used in the present invention, and FIG. and 5 is synthetic papermaking, 6
7 indicates a flat bottom portion of the container, 7 a body portion, and 8 a flat range portion.

Claims (1)

[Claims] (1) Heat-resistant synthetic paper containing a paper substrate with an elongation of 1.8% or more in the longitudinal and transverse directions, fibers provided on both sides of the paper substrate via an adhesive layer, and an inorganic filler that also serves as a flame retardant. A heat-resistant paper container characterized in that it is formed by press-molding a laminate consisting of the following into the shape of a seamless container with a bottom.