JPWO2020054774A1 - Heat-resistant paper materials and heat-resistant paper containers - Google Patents

Abstract

Provided are a heat-resistant paper material having excellent adhesion between polyester and paper as a base material and having excellent shape retention when molded, and a heat-resistant paper container using the same. The heat-resistant paper material is a microwave oven in which a polybutylene terephthalate resin is laminated on the heat-resistant paper, and a laminate is formed so that the crystallization ratio of the polybutylene terephthalate resin after lamination is 10 to 30%. A heat-resistant paper container that can be used for heat treatment of 160 to 220 ° C., the heat-resistant paper has a smoothness of less than 50 seconds and a weighing of 100 g / m2 or more as defined in JIS P8119 of the laminated surface.

Description

The present invention relates to a heat-resistant paper material and a heat-resistant paper container.

In recent years, foods that can be cooked as they are using a cooking machine such as a microwave oven or an oven have become common. Paper, pottery, plastic, heat-resistant glass, aluminum, etc. are used as the container, and each of them is used properly according to the purpose.

Among them, containers using paper are widely used because they have advantages such as low cost and easy disposal. Here, as the container using paper, a container in which a heat-resistant synthetic resin film is laminated on one side or both sides of the paper to form a composite material is used. As the heat-resistant synthetic resin, polyethylene terephthalate resin, polymethylpentene resin, polypropylene resin and the like are used. In addition, containers using such paper are widely used for purposes other than holding food.

However, paper containers laminated with polyethylene terephthalate resin are required to improve the peelability from the contents of foods and the like when heat-treated such as cooking, and reduce the adhesion of bread and cakes. Was sought. Further, especially in the use of holding food, it has been required to reduce the change in the taste and smell of the food caused by the paper container.

In addition, paper containers laminated with polymethylpentene resin are required to have improved heat-sealing properties and gas barrier properties. Especially in applications for holding foods, it is difficult to transfer the paper odor to foods, and the contents of foods. It was required to prevent the odor from leaking to the outside. Further, it is also required to increase the impact strength at low temperature, and it is required that the container is not easily damaged even if it is dropped during transportation (for example, when it is taken out from a freezer or the like).

In addition, paper containers laminated with polypropylene resin are required to have high heat resistance and can be used for high-temperature heat treatment. Especially for food-holding applications, containers suitable for high-temperature cooking of foods containing a large amount of oil. Was sought. Further, it is required to enhance the gas barrier property, and it is also required to make it difficult for the paper odor to be transferred to the food and to make it difficult for the food odor of the contents to leak to the outside, especially in the use of holding food.

In order to solve such a problem, Patent Document 1 discloses a paper container in which a polybutylene terephthalate resin is laminated. This paper container has a great advantage that the flavor of the food after cooking is not impaired, especially when used for holding food, and is suitable as a paper container for cooking food. However, although the paper container for cooking proposed in Patent Document 1 is suitable for cooking in a microwave oven, it can sufficiently withstand high-temperature heat treatment and has high moldability into a container. Was sought.

Further, in Patent Document 2, polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, polyethylene terephthalate-isophthalate copolymer or 1,4-dicyclohexanedimethylene terephthalate-isophthalate copolymer is applied to a substrate film or sheet such as paper. A polyester-coated laminated film provided with a low crystallinity polyester layer formed by extruding and laminating while maintaining the ratio of the ultimate viscosity of the resin after extrusion to the ultimate viscosity of the resin before extrusion at 85% or more. Proposed. It is described that this laminate is excellent in chemical resistance, oil resistance, gas blocking property, and immersion resistance of polyester, and exhibits appropriate heat sealing property. However, what is specifically described in the examples is polyethylene terephthalate or a copolymer thereof, and polybutylene terephthalate resin is not described. Further, the polyester-coated laminated film of Patent Document 2 is not suitable for use in heat treatment at a high temperature as assumed by the paper container of the present invention in terms of deformation, discoloration, and the like.

Further, Patent Document 3 proposes a molded product comprising a resin composition composed of a polybutylene terephthalate resin having a terminal carboxyl group content of 35 mm equivalent / kg or less and an antioxidant. This molded product has solvent extraction resistance, but the container made of this molded product is not intended for heat treatment at high temperatures, and is a laminate laminated on heat-resistant paper and heat resistance formed by molding it. Nothing is suggested about the usefulness of the sex paper container.

Further, Patent Document 4 proposes a heat-resistant paper container for cooking, which is formed by molding a laminate obtained by laminating a polybutylene terephthalate resin having a terminal carboxyl group content of less than 60 mm equivalent / kg on heat-resistant paper. ing. On the other hand, the adhesion between the polyester and the paper as the base material is further improved, and the shape of the heat-resistant paper material is maintained when it is molded into the heat-resistant paper container even when thick paper is used. There was a need for a method to increase the amount of heat.

Japanese Unexamined Patent Publication No. 01-070620 JP-A-55-166247 Japanese Unexamined Patent Publication No. 10-025404 Japanese Unexamined Patent Publication No. 2000-093296

The present invention has been made in order to solve the above problems, and is a heat-resistant paper material having excellent adhesion between polyester and paper as a base material and excellent in maintaining shape when molded. , An object of the present invention is to provide a heat-resistant paper container using the same.

The present inventors have conducted intensive studies to solve the above problems. As a result, they have found that the above problems can be solved by laminating a polybutylene terephthalate resin on a surface of heat-resistant paper having a low smoothness, and have completed the present invention.
More specifically, the present invention provides the following.

(1) In the heat-resistant paper container of the present invention, a polybutylene terephthalate resin is laminated on heat-resistant paper, and a laminate is formed so that the crystallization ratio of the laminated polybutylene terephthalate resin is 10 to 30%. A heat-resistant paper container that can be used in a microwave oven and a heat treatment process of 160 to 220 ° C., the heat-resistant paper has a smoothness of less than 50 seconds specified in JIS P8119 on the laminated surface and is weighed. It is a heat-resistant paper container having a value of 100 g / m ² or more.

(2) Further, in the heat-resistant paper container of the present invention, the polybutylene terephthalate resin has a terminal carboxyl group content of less than 60 mm equivalent / kg, and the heat-resistant paper container is used for cooking (1). ) Is the heat-resistant paper container.

(3) Further, in the heat-resistant paper container of the present invention, the heat-resistant paper according to (1) or (2), wherein the heat-resistant paper has a smoothness of less than 30 seconds specified in JIS P8119 on the laminated surface. It is a container.

(4) Further, the heat-resistant paper container of the present invention is used for applications in which [content weight (g) ÷ volume (cm ³ )] ÷ [weighing (g / m ² )] is 0.001 or more. The heat-resistant paper container according to any one of (1) to (3).

(5) The heat-resistant paper material of the present invention comprises a laminated body in which a polybutylene terephthalate resin is laminated on heat-resistant paper so that the crystallization ratio of the polybutylene terephthalate resin after lamination is 10 to 30%. A heat-resistant paper material that can be used in a microwave oven and a heat treatment process of 160 to 220 ° C., the heat-resistant paper has a smoothness of less than 50 seconds specified in JIS P8119 on the laminated surface, and weighs 100 g / g. It is a heat-resistant paper material having m ² or more.

(6) Further, in the heat-resistant paper material of the present invention, the polybutylene terephthalate resin has a terminal carboxyl group content of less than 60 mm equivalent / kg, and the heat-resistant paper material is used for cooking (5). ) Is the heat-resistant paper material described in.

(7) The heat-resistant paper according to (5) or (6), wherein the heat-resistant paper of the present invention has a smoothness of the laminated surface of less than 30 seconds specified in JIS P8119. It is a material.

(8) Further, the heat-resistant paper material of the present invention is used for a container in which [content weight (g) ÷ volume (cm ³ )] ÷ [weighing (g / m ² )] is 0.001 or more. The heat-resistant paper material according to any one of (5) to (7).

(9) The method for producing a heat-resistant paper material of the present invention is a microwave oven in which a polybutylene terephthalate resin is laminated on heat-resistant paper so that the crystallization ratio of the laminated polybutylene terephthalate resin is 10 to 30%. A method for producing a heat-resistant paper material for heat treatment that can be used in heat treatment reaching 160 to 220 ° C., the heat-resistant paper has a smoothness of less than 50 seconds specified in JIS P8119 on the laminated surface, and is weighed. This is a method for producing a heat-resistant paper material, which uses a material having a value of 100 g / m ² or more.

(10) Further, in the method for producing a heat-resistant paper container of the present invention, the polybutylene terephthalate resin having a terminal carboxyl group content of less than 60 mm equivalent / kg is used, and the heat-resistant paper material is cooked by heating. This is the method for producing a heat-resistant paper material according to (9), which is used in.

(11) Further, in the method for producing a heat-resistant paper container of the present invention, the heat-resistant paper having a smoothness of less than 30 seconds specified in JIS P8119 of the laminated surface is used (9) or (10). The method for producing a heat-resistant paper material according to.

(12) The method for producing a heat-resistant paper container of the present invention is a step of molding the heat-resistant paper material using the heat-resistant paper material obtained by the production method according to any one of (9) to (11). It is a method of manufacturing a heat-resistant paper container having.

(13) Further, in the method for producing a heat-resistant paper container of the present invention, [content weight (g) ÷ volume (cm ³ )] ÷ [weighing (g / m ² )] is 0.001 or more by the molding. The method for manufacturing a heat-resistant paper container according to (12), wherein the container is formed.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a heat-resistant paper material having excellent adhesion between polyester and paper as a base material and excellent in retaining shape when molded, and a heat-resistant paper container using the same. it can.

Further, according to the present invention, it is possible to provide a heat-resistant paper material having excellent handleability and moldability, and also to maintain the surface texture of the container after heat treatment at a high temperature, and to the contents. It is also possible to provide a heat-resistant paper container suitable as a heat-resistant container for heat treatment at a high temperature without the transfer of the polymer odor. Therefore, even when holding food, it has excellent storage stability, can be cooked as it is in a cooking machine such as a microwave oven or a microwave oven, is tasteless and odorless, and has the taste and odor of food in a container. It is also possible to provide a heat-resistant paper material that does not change to and a heat-resistant paper container using the same.

Hereinafter, specific embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within the scope of the object of the present invention.

<About heat-resistant paper materials and their manufacturing methods>
In the heat-resistant paper material according to the present invention, polybutylene terephthalate resin is laminated on the laminated surface of heat-resistant paper having a smoothness of the laminated surface in JIS P8119 of less than 50 seconds and a weighing of 100 g / m ² or more. It is made of a laminated body in which the crystallization ratio of the polybutylene terephthalate resin after lamination is 10 to 30% in order to prevent tearing during molding and to prevent deformation during heat treatment.

Further, as the method for producing a heat-resistant paper material according to the present invention, a heat-resistant paper having a smoothness of less than 50 seconds and a weighing of 100 g / m ² or more specified in JIS P8119 on the laminated surface is used. , Polybutylene terephthalate resin is laminated on this heat-resistant paper so that the crystallization rate of the laminated polybutylene terephthalate resin is 10 to 30%, and reaches 160 to 220 ° C. in a microwave oven. A heat-resistant paper material that can be used by heat treatment is obtained.

[Polybutylene terephthalate resin]
The polybutylene terephthalate resin used for heat-resistant paper materials contains a diol component containing 1,4-butanediol, which is a polyvalent alcohol component, as a main component, and a dicarboxylic acid containing terephthalic acid, which is a polyvalent carboxylic acid component, as a main component. It is a polyester having a butylene terephthalate unit as a main repeating unit obtained by condensing a component or an alcohol ester component thereof, and may be a copolymer mainly composed of polybutylene terephthalate as long as the effect of the present invention is not impaired. .. Here, the polybutylene terephthalate resin may contain 60 mol% or more of the butylene terephthalate unit among the ester units of the polyvalent carboxylic acid-polyhydric alcohol.

This polybutylene terephthalate resin has a carboxyl group content at the end of the polymer chain (a value obtained by dissolving in benzyl alcohol at 215 ° C. and titrating with sodium hydroxide) at 60 milliequivalent / kg (hereinafter, "m equivalent"). It is abbreviated as "/ kg"), and more preferably less than 50 m equivalent / kg.

By setting the carboxyl group content to 60 m equivalent / kg or less, hydrolysis of the resin is suppressed even when heat treatment is performed at a high temperature, so that the polybutylene terephthalate resin on the surface of the heat-resistant paper material loses its luster. Problems such as poor tactile sensation can be reduced. Further, since the polymer odor from the heat-resistant paper material is reduced, the transfer of the polymer odor to the contents can be reduced. On the other hand, when the heat-resistant paper material is used for holding other than food, or when the heat-resistant paper material does not require an excellent appearance, the carboxyl group content may be more than 60 m equivalent / kg.

Examples of the method for obtaining such a polybutylene terephthalate resin include a method of reducing the amount of oligomers of the eluted component by solid-phase polymerization of the polybutylene terephthalate resin obtained by a known synthetic method, and a carboxyl group (-OH). There is a method of reducing the amount by reacting with a reactive monomer containing (group).

Polybutylene terephthalate resins used for heat-resistant paper materials include colorants such as dyes and pigments, plasticizers, antioxidants, ultraviolet absorbers, antistatic agents, and surfactants, as long as the effects of the present invention are not impaired. Additives such as lubricants, crystallization accelerators and retarders can be included. A plurality of these may be contained depending on the purpose. Further, other thermoplastic resins and inorganic fillers can be contained according to the required performance as long as the effects of the present invention are not impaired. In particular, when heat-resistant paper materials are used for food retention, substances that are not extracted by food when heat-treated and do not contaminate food should be used as these additives, thermoplastic resins, and inorganic fillers. Is preferable.

[Heat-resistant paper]
The heat-resistant paper used for the heat-resistant paper material has a weighing capacity of 100 g / m ² or more, and the smoothness of the surface on which the polybutylene terephthalate resin is laminated (hereinafter referred to as "laminated surface") is 50 in JIS P8119. Use less than a second. Among them, the smoothness of the laminated surface of the heat-resistant paper in JIS P8119 is preferably less than 30 seconds, more preferably 28 seconds or less. The present inventors have found that even when the smoothness of the laminated surface is set to less than 50 seconds, necking does not occur in the film when the film of polybutylene terephthalate resin is laminated on the heat-resistant paper. Then, by using a heat-resistant paper having a low smoothness of the laminated surface (the number of seconds of smoothness is small), the laminated surface becomes a rough surface and the polybutylene terephthalate resin is easily held. Therefore, the polybutylene terephthalate resin is used. And heat-resistant paper can be improved. As a result, even when the heat-resistant paper is weighed and the thickness is increased, the strength of the joint when the heat-resistant paper material is molded is increased and the shape of the heat-resistant paper is maintained. It is possible to improve the shape retention of the heat-resistant paper container.

Here, the smoothness (Beck method smoothness) in JIS P8119 is that a certain amount of atmospheric pressure air flows between a test piece and a ring-shaped flat surface that are in contact with each other under specific conditions under a specific initial differential pressure. The required time (seconds). The smoothness test piece was placed on the test stand on a glass plane (diameter 37.4 mm ± 0.05 mm, circular effective plane area 10cm ² ± 0.05cm ^2), a rubber pressing plate (or diameter 45 mm) It is pressed down with a pressure of 1000 kPa using the above, and atmospheric pressure air is sucked in from the contact surface between the glass plane and the test piece vacuumed to 48.0 to 50.7 kPa, and it takes time (seconds) for 10 cc of air to enter. ) Is measured. For a sample having particularly high smoothness (smoothness of 300 seconds or more), the time (seconds) required for 10 cc of air to enter may be measured and the value may be multiplied by 10 to obtain a smoothness value (seconds). ..

Further, as the heat-resistant paper, one having a basis weight of 100 g / m ² or more is used. Here, the basis weight of the heat-resistant paper can be preferably 120 g / m ² or more, and more preferably 150 g / m ² or more. By using heat-resistant paper with a basis weight of 100 g / m ² or more, it is possible to create a heat-resistant paper container that does not easily deform even when the contents are heavy, without impairing the workability of the container shape. , A heat-resistant paper material as the material can be obtained. On the other hand, the upper limit of the basis weight of the heat-resistant paper is preferably 500 g / m ² , more preferably 400 g / m ² , and further preferably 300 g / m ² . By using a heat-resistant paper having a basis weight of 500 g / m ² or less, it is possible to reduce cracks and tears in the corners and edges of the obtained paper container when the heat-resistant paper container is obtained by heat molding. Can be done.

As the heat-resistant paper used in the present invention, either synthetic paper that does not use pulp fibers or pulp paper that uses pulp fibers such as wood pulp as a raw material can be used. Among them, it is more preferable to use pulp paper from the viewpoint of heat resistance. When heat-resistant paper is used for holding food, it is preferable to use a heat-resistant paper that can be used as a cooking paper container or wrapping paper for wrapping food or the like.

The heat-resistant paper used in the present invention includes stretched polyethylene terephthalate film, polyvinylidene chloride-coated stretched polyethylene terephthalate film, cellophane, low-density, medium-density or high-density polyethylene, ionomer, ponopropylene, etc., within an acceptable range of heat resistance. A laminate of a plastic film, a sheet, an aluminum foil, or the like and heat-resistant paper may be used, but it is not necessary to use such a laminate from the viewpoint of cost, polymer odor, disposal, and the like.

[Lamination of polybutylene terephthalate resin on heat-resistant paper]
The heat-resistant paper material of the present invention comprises a laminate in which polybutylene terephthalate resin is laminated on the laminated surface of heat-resistant paper. For laminating the polybutylene terephthalate resin on the heat-resistant paper, for example, a method is used in which the polybutylene terephthalate resin is heated and melted and this resin is supplied to the laminated surface of the heat-resistant paper to form a laminated layer. At this time, by controlling the conditions for heating and melting the polybutylene terephthalate resin and laminating it on heat-resistant paper, the crystallization rate (value measured by the X-ray diffraction method) of the laminated polybutylene terephthalate resin is set to 10. It is preferably in the range of ~ 30%.

By setting the crystallization rate of the polybutylene terephthalate resin to 10% or more, it is possible to reduce the crystallization of the polybutylene terephthalate resin during the heat treatment and suppress the deformation of the container caused by the shrinkage due to the crystallization during the heat treatment. it can. Further, by reducing the crystallization rate of the polybutylene terephthalate resin to 30% or less, the flexibility, stretchability, and toughness when the laminated laminate is formed into a container or the like by a hot press or the like is enhanced, and the laminate layer is torn. Can be reduced. Therefore, by controlling the crystallization ratio in the range of 10 to 30%, it is possible to suppress container moldability, shape deformation and deformation during heat treatment, and changes in appearance.

When laminating on heat-resistant paper, as a means for obtaining a polybutylene terephthalate resin laminate having such a crystallization ratio, control the temperature of the resin when laminating the polybutylene terephthalate resin on the heat-resistant paper, or after laminating. The temperature of the chill roll that cools and pressurizes the laminate of the above can be controlled, and the desired crystallization rate can be controlled by these.

Here, the temperature of the resin when laminating the polybutylene terephthalate resin can be, for example, 260 ° C. or higher, preferably 280 ° C. or higher. On the other hand, the upper limit of the resin temperature can be, for example, 300 ° C. or lower.

Further, when cooling and pressurizing the laminate after laminating the polybutylene terephthalate resin, the temperature of the chill roll is preferably adjusted to 40 to 70 ° C, more preferably 50 to 70 ° C.

As a method for laminating the polybutylene terephthalate resin on heat-resistant paper, conventional methods such as extrusion molding, injection molding, vacuum forming, compression molding, press molding and the like can be used. Further, the laminated product may be subjected to secondary processing such as cutting.

The thickness of the polybutylene terephthalate resin layer in the laminate obtained by laminating can be appropriately set according to the characteristics of the polybutylene terephthalate resin and the like, and can be set, for example, in the range of 5 μm or more and 60 μm or less. By setting this thickness to 5 μm or more, it is possible to reduce the occurrence of pinholes and uneven thickness due to surging, so that a laminated layer can be stably obtained. The upper limit of the thickness of the polybutylene terephthalate resin layer is preferably 60 μm or less because of the ease of forming the laminate layer, the ease of container molding, and economic reasons.

Here, the laminate laminated with the polybutylene terephthalate resin may be composed of two layers of the polybutylene terephthalate resin and heat-resistant paper, or may be composed of three or more layers including other layers. At this time, it is preferable that the polybutylene terephthalate resin layer is provided on at least one surface of the laminate.

As an example of the laminating method, in addition to the examples described in the examples, a molten polybutyl terephthalate resin at 290 to 300 ° C. is used by a T-die having a slit width of 1.0 mm using an extruder having a diameter of 115 mm. An example is given in which laminating is performed on a paperboard weighing 150 to 350 g / m ² at a laminating speed of 35 m / min so as to have a thickness of 10 to 50 μm. The laminate obtained by laminating using this method and winding while cooling and pressurizing with a chill roll whose temperature is adjusted to 40 to 60 ° C. is controlled to a crystallization rate in the above range. ..

[Characteristics and applications of heat-resistant paper materials]
The heat-resistant paper material of the present invention has excellent heat resistance and moldability, does not lose or deform the shape of the container when filled with the contents, and does not change the appearance after the heat treatment, and has appropriate adhesion and peeling to the contents. Has sex. At the same time, it is excellent in maintaining the shape and surface texture of the container after heat treatment at high temperature, and there is no transfer of polymer odor to the contents. Therefore, the heat-resistant paper material of the present invention is used for heat treatment in a microwave oven, or for heat treatment at a high temperature where the temperature of the heat-resistant paper material reaches about 160 to 190 ° C, or more severely 190 to 220 ° C. For example, it can be preferably used for cooking in a microwave oven or an oven.

However, heat treatment of the heat-resistant paper material at a temperature equal to or higher than the melting point of the polybutylene terephthalate resin is not preferable because the polybutylene terephthalate resin melts. From this point of view, taking heat treatment when food is used as an example, baking of tarts, sponge cakes, fruit cakes, pound cakes, shoes, madeleines, etc., which are generally said to be in the low to medium temperature range. It is most suitable for cooking gratin, doria, etc. Of course, as long as it does not exceed the melting point of the polybutylene terephthalate resin, it is also suitable for heat treatment of other foods and contents other than foods.

As will be described later, such a heat-resistant paper material can be suitably used for producing a heat-resistant paper container such as a food container. Further, it can be used as it is as a thick wrapping paper or the like for wrapping food or the like, and can be formed into a bag or the like.

<About heat-resistant paper containers and their manufacturing methods>
In the heat-resistant paper container according to the present invention, polybutylene terephthalate resin is laminated on the laminated surface of heat-resistant paper having a smoothness of the laminated surface in JIS P8119 of less than 50 seconds and a weighing of 100 g / m ² or more. It is made of a laminated body in which the crystallization ratio of the polybutylene terephthalate resin after lamination is 10 to 30% in order to prevent tearing during molding and to prevent deformation during heat treatment.

Further, the method for manufacturing a heat-resistant paper container according to the present invention is obtained by molding this heat-resistant paper material using the above-mentioned heat-resistant paper material.

The means for molding the heat-resistant paper material is not particularly limited as long as the laminated structure of the heat-resistant paper material is maintained, and various known methods can be adopted. As an example, a heat-resistant paper container can be obtained by cutting a heat-resistant paper material into an appropriate size using a heat-press molding machine and heat-molding it by a heat press or the like.

The heat-resistant paper container according to the present invention is manufactured using heat-resistant paper having a specific weighing capacity, and is excellent in maintaining its shape when the contents are filled in the container. The weight of the contents relative to the volume can be increased. In addition, it can withstand contents having a large specific gravity. Specifically, it is preferably used in applications where the value of [content weight (g) ÷ volume (cm ³ )] ÷ [weighing (g / m ² )] is 0.001 or more, and the value of the above formula is It is more preferably used for applications having a value of 0.003 or more, and further preferably used for applications having a value of 0.005 or more. The upper limit of this value is not particularly limited, but in applications where this value is extremely large, there is a concern that the container may not be able to withstand the weight of the contents and may be deformed. Therefore, for example, it may be 0.05 or less. , 0.01 or less.

This heat-resistant paper container may be configured to have a polybutylene terephthalate resin layer on one or both of the innermost layer (the surface layer on the side in contact with the contents) and the outermost layer (the surface layer on the side not in contact with the contents). preferable. Among them, when it is preferable that the contents and the container are in proper contact with each other, it is preferable to form polybutylene terephthalate resin as the innermost layer, but when it is preferable that the contents and the container are in strong contact with each other. The heat-resistant paper may be formed as the innermost layer. By using a polybutylene terephthalate resin layer for one or both of the innermost layer and the outermost layer depending on the type of contents and the process after filling the contents, a container corresponding to each request can be obtained. ..

Further, the outermost layer of the laminate may be configured to be heat-resistant paper, but by configuring the polybutylene terephthalate resin to be the outermost layer, the paper is soaked or stained with water due to moisture adhering to the outside of the container. It is possible to further improve the commercial value because the appearance is glossy and glossy.

In particular, by using the polybutylene terephthalate resin layer as the innermost layer of the heat-resistant paper container and combining it with a known appropriate lid material, the polybutylene terephthalate resin has heat-sealing properties, gas barrier properties, low-temperature impact resistance, and easy peeling properties. It is possible to obtain a container that takes advantage of features such as heat resistance. As an example, after filling a container with gratin, doria, etc., it can be completely sealed by heat sealing and stored frozen. Further, when cooking this, after taking it out of the freezer, the lid can be easily peeled off due to its easy peeling property, so that it can be immediately cooked in an oven or the like.

Hereinafter, the present invention will be specifically described with reference to Examples, Comparative Examples and Reference Examples, but the present invention is not limited to these Examples.

Various paperboards made of pulp paper having smoothness and weighing values in JIS P8119 shown in Examples, Comparative Examples and Reference Examples in Table 1 were used as heat-resistant papers, and had an intrinsic viscosity of 0.88 dL / g and a terminal. Polybutylene terephthalate resin having a carboxyl group content of 15 m equivalent / kg was laminated on each heat-resistant paper. Here, the polybutylene terephthalate resin is laminated by using a 90 mmφ extruder and using a T-die having a slit width of 0.8 mm so that the molten polybutylene terephthalate resin at 290 to 300 ° C. has a thickness of 25 μm. Laminating was performed at a laminating speed of 35 m / min. Next, a heat-resistant paper material was obtained by winding up the obtained laminate while cooling and pressurizing with a chill roll whose temperature was adjusted to 60 ° C.

The polybutylene terephthalate resin laminated on the obtained heat-resistant paper material was peeled off from the heat-resistant paper, and the crystallization rate was measured by an X-ray diffraction method and found to be 20%.

Further, the obtained heat-resistant paper material is cut to a predetermined size by punching using a hot press molding machine, and heat-molded at 140 ° C. so that the polybutylene terephthalate resin layer is on the inside. By setting, a heat-resistant paper container having a volume of 400 cm ³ was obtained.

[Evaluation]
The performance of the obtained heat-resistant paper material and the heat-resistant paper container obtained by baking a cake dough having a weight of 150 g inside was evaluated for the following items. The evaluation results are shown in Table 1.

Regarding the adhesion of the laminated layer, the obtained heat-resistant paper material was laminated with the obtained heat-resistant paper material at a test piece width of 25 mm and a crosshead speed of 100 mm / min according to the 180 ° peeling test specified in JIS K6854-2. The butylene terephthalate resin was peeled off from the heat-resistant paper, and the state of the peeled surface was visually observed. At this time, the cases where the heat-resistant paper and the polybutylene phthalate resin are firmly bonded and the laminated surface of the heat-resistant paper adheres to the polybutylene terephthalate resin side as a whole are marked with "◎" and "○". The case where the heat-resistant paper layer, which is the base material, is torn is marked with "⊚", and the case where the heat-resistant paper layer is not torn but the inside of the heat-resistant paper layer is peeled off is marked with "○". In addition, when the heat-resistant paper is partially attached to the polybutylene terephthalate resin side and the heat-resistant paper is partially peeled off at the interface, "△" indicates that almost the entire surface is peeled off at the interface between the polybutylene terephthalate resin laminate layer and the heat-resistant paper (polybutylene terephthalate resin side). The case where heat-resistant paper does not adhere to the surface is marked with "x". The results are shown in Table 1.

Regarding the handleability of the heat-resistant paper material, a roll of the heat-resistant paper material is set in the heat-resistant paper material when the obtained heat-resistant paper material is punched using the heat-press molding machine. Judgment based on handleability and productivity (refers to the number of discarded shots in punching and the required amount of edge rails and feed rails, and the smaller the loss due to these, the better the productivity). did. In terms of handleability and productivity, those excellent in both were marked with "○", those inferior in any of these were designated as "Δ", and those inferior in both were marked with "x". In addition, the ones that are particularly excellent in handleability and require only a few discarded shots until the start of continuous molding are marked with "◎". The results are shown in Table 1.

Regarding moldability, when heat-resistant paper material is molded and heat-set, cracks or tears occur in the corners and edges as "x", and whitening occurs as "△". Those that could be molded without problems were marked with "○". The results are shown in Table 1.

Regarding the shape retention of the container, a commercially available home-use cake dough (cake mix M520 manufactured by Nippon Flour Milling Co., Ltd.) cooked according to the cooking instructions of the cake dough is filled in the obtained heat-resistant paper container, and the container is filled. The deformed state of was visually confirmed. The shape stability is evaluated as "○" if the container is not deformed even after filling the cake dough, and "x" if the container is deformed due to the weight of the filled cake dough. did. The results are shown in Table 1.

As shown in Table 1, the heat-resistant paper materials and heat-resistant paper containers obtained in Examples 1 and 2 have all of the adhesion of the laminated layer to the heat-resistant paper, the moldability, and the shape retention of the container. It became "○", and all of them were excellent results. Further, in the heat-resistant paper material and the heat-resistant paper container obtained in Examples 1 and 2, the handleability of the heat-resistant paper material was "⊚", which was a particularly excellent result in terms of handleability. On the other hand, regarding the heat-resistant paper material and the heat-resistant paper container obtained in Reference Example 1, the adhesiveness and the shape retention of the container were "○", which was an excellent result, but the moldability was "△". The result was slightly inferior in terms of moldability. Further, in the heat-resistant paper material obtained in Comparative Example 1, the adhesion of the laminated layer to the heat-resistant paper was "x", which resulted in inferior adhesion to the heat-resistant paper. Further, with respect to the heat-resistant paper material and the heat-resistant paper container obtained in Comparative Examples 1 to 3, one or both of the adhesiveness and the shape retention of the container became "Δ" or "×", and one or both of them. The result was inferior in terms of. Further, the heat-resistant paper materials obtained in Reference Examples 1 and Comparative Examples 1 to 3 have a handleability of "○", which is excellent in terms of handleability, but is compared with Examples 1 and 2. The result was inferior.

Further, the heat-resistant paper containers of each Example, Comparative Example, and Reference Example were filled with the cake dough used for the evaluation of shape retention, and baked at 200 ° C. for 18 minutes according to the cooking instructions of the cake dough. Luster on the surface of the container (loss of gloss on the surface of the polybutylene terephthalate resin layer compared to before firing), smoothness on the surface of the container (roughness compared to before firing when the surface of the polybutylene terephthalate resin layer is patted with a fingertip) When the polymer odor (increased) and the polymer odor (the odor of tetrahydrofuran on the container itself and the surface of the cake) were evaluated, the gloss and smoothness of the surface of the container did not change, and the odor of tetrahydrofuran on the container itself and the surface of the cake did not occur. It was a good result.

Therefore, according to the present invention, it is possible to obtain a heat-resistant paper material having excellent adhesion between polyester and paper as a base material, and also having excellent handleability and moldability, and the shape retention and surface properties of the container. It is presumed that a heat-resistant paper container suitable as a heat-resistant container for heat treatment at a high temperature can be obtained because it has excellent retention and does not transfer the polymer odor to the contents.

Claims (13)

Polybutylene terephthalate resin is laminated on heat-resistant paper, and a laminate is formed so that the crystallization rate of the polybutylene terephthalate resin after lamination is 10 to 30%, in a microwave oven and at 160 to 220 ° C. A heat-resistant paper container that can be used in the heat treatment that reaches
The heat-resistant paper is a heat-resistant paper container having a smoothness of the laminated surface specified in JIS P8119 for less than 50 seconds and a weighing of 100 g / m ² or more. The polybutylene terephthalate resin has a terminal carboxyl group content of less than 60 mm equivalent / kg.
The heat-resistant paper container according to claim 1, wherein the heat-resistant paper container is used for cooking. The heat-resistant paper container according to claim 1 or 2, wherein the heat-resistant paper has a smoothness of a laminated surface of less than 30 seconds as defined in JIS P8119. The heat-resistant paper according to any one of claims 1 to 3, which is used in an application in which [content weight (g) ÷ volume (cm ³ )] ÷ [weighing (g / m ² )] is 0.001 or more. container. Polybutylene terephthalate resin is laminated on heat-resistant paper, and the polybutylene terephthalate resin after lamination is composed of a laminated body in which the crystallization ratio is 10 to 30%, in a microwave oven and heat treatment reaching 160 to 220 ° C. A heat-resistant paper material that can be used
The heat-resistant paper is a heat-resistant paper material having a smoothness of less than 50 seconds and a weighing of 100 g / m ² or more specified in JIS P8119 on the laminated surface. The polybutylene terephthalate resin has a terminal carboxyl group content of less than 60 mm equivalent / kg.
The heat-resistant paper material according to claim 5, wherein the heat-resistant paper material is used for cooking. The heat-resistant paper material according to claim 5 or 6, wherein the heat-resistant paper has a smoothness of a laminated surface of less than 30 seconds specified in JIS P8119. The heat resistance according to any one of claims 5 to 7, which is used for a container in which [content weight (g) ÷ volume (cm ³ )] ÷ [weighing (g / m ² )] is 0.001 or more. Sex paper material. A heat-resistant paper that can be used in a microwave oven and a heat treatment process of 160 to 220 ° C., in which polybutylene terephthalate resin is laminated on heat-resistant paper so that the crystallization rate of the polybutylene terephthalate resin after lamination is 10 to 30%. It is a method of manufacturing wood,
A method for producing a heat-resistant paper material, which uses a heat-resistant paper having a smoothness of less than 50 seconds and a weighing of 100 g / m ² or more as defined by JIS P8119 on the laminated surface. As the polybutylene terephthalate resin, a resin having a terminal carboxyl group content of less than 60 mm equivalent / kg was used.
The method for producing a heat-resistant paper material according to claim 9, wherein the heat-resistant paper material is used for cooking. The method for producing a heat-resistant paper material according to claim 9 or 10, wherein the heat-resistant paper has a smoothness of less than 30 seconds specified in JIS P8119 on the laminated surface. A method for producing a heat-resistant paper container, which comprises a step of molding the heat-resistant paper material using the heat-resistant paper material obtained by the production method according to any one of claims 9 to 11. The heat-resistant paper container according to claim 12, wherein a container having [content weight (g) ÷ volume (cm ³ )] ÷ [weighing (g / m ² )] of 0.001 or more is formed by the molding. Manufacturing method.