JP2016120948A - Paper-made container and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper-made container capable of preventing bubbles from remaining on the liquid surface or the like of a content (1).SOLUTION: A paper-made container 10 includes a container main body 3 including a trunk part 1 having a trunk part joining part 4 and a bottom plate part 2, and a resin layer provided in at least the inner surface side of the trunk part 1 and the bottom plate part 2, and is characterized in that the surface roughness Ra of the resin layer provided in the inner surface side of the trunk part is 0.4 μm or more to 1.5 μ or less. 2) When the fuzz part of the end surface of the trunk joining part 4 is a part where a line connecting the valley of the end surface is set as a base line, a straight line parallel to the base line is drawn at a position away from the baseline by 15 μm, and the straight line and the fuzz intersect each other, a fuzz rate which is a rate of the fuzz part at the end surface of the trunk joining part 4 is equal to or less than 30%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a paper container and a method for manufacturing the paper container.

Paper containers are widely used as containers for food. Paper containers are also used as containers for packaging foods such as jelly and yogurt containing a thickener, gelling agent or coagulant. These foods are usually filled with a thickener, gelling agent or coagulant at a temperature of room temperature or higher, and then sealed with a lid and refrigerated to increase viscosity, gelation, It is solidified. At this time, bubbles may rise to the liquid level of the contents, and the appearance may deteriorate due to the bubbles not solidifying. Moreover, about transparent foodstuffs, such as jelly, an external appearance will deteriorate by seeing the bubble which stays in the contents.
Patent Document 1 discloses a yogurt in which the surface roughness of the low density polyethylene resin layer that comes into contact with yogurt during filling is 1.5 to 2.0 μm in average roughness (Ra), and no bubbles or cracks are generated on the yogurt surface. A paper cup is disclosed.

JP 2003-192083 A

However, even when the surface roughness (Ra) of the thermoplastic resin laminate surface of the paper material is 1.5 to 2.0 μm, as in the paper material used in the manufacture of the paper cup described in Patent Document 1, the content The problem that the foam does not disappear on the liquid surface of the object and solidifies and deteriorates the appearance is not completely solved, and there is room for further study.
The present invention has been made in view of the above circumstances, and is a paper container in which bubbles are prevented from solidifying without disappearing after filling with a content containing a thickener, a gelling agent or a coagulant, and It is an object to provide a method for manufacturing a paper container.

  As a result of diligent research to solve the above problems, the present inventors set the surface roughness of the resin layer provided on the inner surface side of the paper material within a predetermined range, thereby reducing the liquid level of the contents, etc. The inventors have found that the remaining of bubbles is further prevented and completed the present invention.

That is, this invention provides the paper container which has the following characteristics, and the manufacturing method of this paper container.
(1) A paper container having a container body composed of a body part having a body part joint part and a bottom plate part, and a resin layer provided on at least the inner surface side of the body part and the bottom plate part,
The paper container, wherein the resin layer provided on the inner surface side of the body portion has a surface roughness Ra of 0.4 μm or more and less than 1.5 μm.
(2) The fluffed portion of the end face of the trunk joint is defined as a line connecting the valleys of the end face, and a straight line parallel to the base line is drawn at a position 15 μm away from the base line. The paper container as described in said (1) whose fluffing rate which is a ratio of the said fluffing part in the end surface of a trunk | drum junction part is 30% or less when it is set as a part.
(3) In the state in which the body joint portion on the inner surface side of the paper container is vertically arranged in water, it adheres adjacent to the end surface of the body joint portion on the inner surface side of the paper container. The paper container according to (1) or (2), wherein the time required for the bubbles to rise 30 mm along the resin layer is 40 seconds or less when the rising speed of the 18 mL bubbles is measured.
(4) The paper container according to any one of (1) to (3), wherein a contact angle between the resin layer on the inner surface side of the trunk portion and water is 60 degrees or greater and 98 degrees or less.
(5) In the method for measuring the sealing property of the joint portion of the container, which is measured by sealing the lid on the paper container and then submerging in water and sending air in an amount of 5 mL / min into the paper container. The paper container according to any one of (1) to (4), wherein the volume of air leaking from the paper container is 3.0 mL or less.
(6) The lubricant according to (1), wherein a lubricant is attached to at least a part of the outer surface side of the body part or at least a part of the inner surface side of the body part, and the lubricant is a liquid paraffin or a silicone-based lubricant. The paper container as described in any one of-(5).
(7) The paper container according to any one of (1) to (6), wherein a food additive adheres to at least a part of the inner surface side of the body portion.
(8) The paper container according to (6) or (7), wherein the lubricant attached to at least a part of the inner surface side of the body portion contains the food additive.
(9) The paper container according to any one of (7) and (8), wherein the food additive has an HLB of 1 to 17.
(10) The food additive is any one or more selected from the group consisting of glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, propylene glycol fatty acid ester, and lecithin. The paper container according to any one of (7) to (9).
(11) The paper container according to any one of (7) to (10), wherein a food additive adheres to the inner surface side of the body part at 0.005 μg / cm ² or more and 17 μg / cm ² or less.
(12) Lubricant adheres to the lower outer peripheral surface which is within 2 cm from the lowermost part on the outer surface side of the body part, the lubricant contains food additive, and the food additive is 0 on the lower outer peripheral surface. The paper container according to any one of (1) to (11), attached at 0.005 μg / cm ² or more and 17 μg / cm ² or less.
(13) In the paper container, a lubricant adheres to an upper inner peripheral surface which is within a range of 2 cm from the uppermost portion on the inner surface side of the body portion, the lubricant contains a food additive, and the upper inner peripheral surface The paper container according to any one of (1) to (12), wherein the food additive adheres to the surface at 0.005 μg / cm ² or more and 17 μg / cm ² or less.
(14) The method for manufacturing a paper container according to any one of (1) to (13), wherein the body portion and the bottom plate portion are bonded together by an expansion sealing method.

  ADVANTAGE OF THE INVENTION According to this invention, after filling the content containing a thickener, a gelling agent, or a coagulant | flocculant, the paper container which prevented the foam from solidifying without disappearing, and the manufacturing method of a paper container are provided. it can.

It is a half section front view showing an example of an embodiment of a paper container concerning the present invention. It is an expanded sectional view showing an example of processed paper which forms a paper container concerning the present invention. It is an expanded sectional view which shows an example of the shape of the trunk | drum junction part of the paper container which concerns on this invention. In the paper container which concerns on invention, it is a schematic diagram explaining the mode of the bubble adhering adjacent to the end surface of the trunk | drum junction part by the side of an inner surface. It is the figure which represented typically the mode of the fluff of the end surface of a trunk | drum junction part. It is a figure explaining the joining method of a trunk | drum and a baseplate part. (A) Expander roll method. (B), (c) Expansion sealing method. It is a figure explaining an example of the mode of joining of a body part and a baseplate part. It is the photograph which copied the state of the fluff of the end surface of a trunk | drum junction part. It is a figure explaining the part stopped in the measurement of the airtightness of the paper container of an Example.

<Paper container>
[Configuration of paper container]
A paper container according to the present invention is a paper container having a container main body composed of a body part having a body part joint part and a bottom plate part, and a resin layer provided on at least the inner surface side of the body part and the bottom plate part. And the surface roughness Ra of the said resin layer provided in the inner surface side of the said trunk | drum is 0.4 micrometer or more and less than 1.5 micrometers.
Hereinafter, an example of an embodiment of a paper container according to the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, a paper container 10 according to the present embodiment is a paper container having a container body 3 composed of a trunk portion 1 having a trunk joint portion 4 and a bottom plate portion 2.
In the paper container 10 of the present embodiment, resin layers are provided on the inner surface side and the outer surface side of the body portion 1 and the bottom plate portion 2. FIG. 2 is an enlarged cross-sectional view illustrating an example of processed paper forming a paper container. On the processed paper 5, an inner surface side resin layer 7 is laminated on the container inner surface side of the paper base material 6, and an outer surface side resin layer 8 is laminated on the outer surface side of the paper base material 6. By laminating the inner surface side resin layer 7 on the inner surface side of the container, water resistance is imparted to the inner surface of the paper container, and the body portions at the body joint portion (to form the body portion into a cylindrical shape) Can be joined by heat sealing between the body portion and the bottom portion. The outer surface side resin layer 8 on the outer surface side of the container is not an indispensable structure in the paper container of the present invention, but the outer surface side resin layer 8 is provided on the outer surface side of the container to fill the contents that need to be refrigerated and frozen. When it does, the rigidity fall by dew condensation can be suppressed.

  FIG. 3 shows an example of the shape of the trunk joint 4 as an enlarged cross-sectional view of the trunk joint 4. The body joint portion 4 is a portion where the processed paper 5 forming the body portion is overlapped and joined. As shown in FIG. 3, the end surface of the processed paper 5 is exposed on the inner surface side and the outer surface side of the paper container. In FIG. 3, the end face on the inner surface side of the paper container 10 is shown as an end face 4a, and the end face on the outer face side of the paper container 10 is shown as an end face 4a '.

[resin]
The inner surface side resin layer 7 and the outer surface side resin layer 8 contain a resin. The types and configurations of the resins contained in the inner surface side resin layer 7 and the outer surface side resin layer 8 may be the same or different from each other.

An example of the resin contained in the inner surface side resin layer 7 is a thermoplastic resin. Examples of the thermoplastic resin include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene, high density polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, and polymethylpentene.
Among these, low density polyethylene (LDPE) or linear low density polyethylene (LLDPE) having a melting point of 100 to 120 ° C. is preferable. Since they are melted at a relatively low temperature by using them, it is easy to heat-seal the body part and the bottom part without gaps, and “unmelted part is not adhered” due to insufficient heating is unlikely to occur.
Further, as the resin contained in the inner surface side resin layer 7, low density polyethylene (LDPE) is more preferable. By using low-density polyethylene (LDPE), when the lid is heat-sealed to the top curl (flange) part of a paper container, the adhesive strength becomes too high to make it difficult to open. be able to.

As resin which the outer surface side resin layer 8 contains, a thermoplastic resin can be illustrated similarly to resin which said inner surface side resin layer 7 contains. Examples of the thermoplastic resin include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene, high density polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, and polymethylpentene.
Further, as shown in FIG. 3, since the inner surface side resin layer 7 and the outer surface side resin layer 8 are bonded to each other in the body portion bonding portion 4, heat sealing between the inner surface side resin layer 7 and the outer surface side resin layer 8 is performed. Since the property is enhanced, the joining can be performed by heat sealing. From such a viewpoint, the combination of resins contained in the inner surface side resin layer 7 and the outer surface side resin layer 8 is, for example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), or medium density polyethylene. May be selected as appropriate. As an example, when the resin contained in the inner surface side resin layer 7 is low density polyethylene (LDPE), the resin contained in the outer surface side resin layer 8 is low density polyethylene (LDPE), linear low density polyethylene (LLDPE). Or medium density polyethylene.

[Surface roughness]
In the paper container 10, the surface roughness Ra of the inner surface side resin layer 7 forming the body portion 1 is 0.4 μm or more and less than 1.5 μm, preferably 0.5 μm or more and 1.4 μm or less. More preferably, it is 5 μm or more and 1.0 μm or less.
The surface roughness Ra of the paper container is an arithmetic average roughness Ra measured in accordance with Japanese Industrial Standard JIS B0601-2013. The surface roughness Ra can be measured using a commercially available stylus type surface roughness measuring instrument.

By making the surface roughness Ra of the inner surface side resin layer 7 within the above range, particularly by making the surface roughness Ra of the inner surface side resin layer 7 smaller than 1.5 μm, the contact area between the bubbles and the thermoplastic resin laminate surface is reduced. Therefore, the hydrophobic bubbles are less likely to adhere to the hydrophobic thermoplastic resin laminate surface, and are easily detached, and bubbles are less likely to remain on the liquid surface of the contents. By setting the surface roughness Ra of the inner surface side resin layer 7 to 0.4 or more, the bubbles are less likely to adhere to the inner surface side resin layer and are easily detached. When the surface roughness Ra is 0.4 or more, the smoothness is lost even after the process of heating the body member and the process of winding the body member by applying hot air to the inner surface side resin layer 7 during heat sealing. Hateful. Further, as the surface roughness of the thermoplastic resin laminate surface is reduced, the paper materials tend to stick to each other when the paper materials are stacked or rolled up, and the paper materials may be difficult to handle. In the inner surface side resin layer 7, by setting the surface roughness Ra to 0.4 or more, it is possible to prevent the paper materials from sticking to each other when the paper materials are stacked or wound up.
When the surface roughness Ra of the inner surface side resin layer 7 is smaller than 0.4 μm, the smoothness of the resin layer is high, and when it is wound on the base paper after the resin is extruded and laminated, the opposite surface to be contacted is also smooth with the resin layer. If it is high, the contact area between the resin layers becomes large, so that it becomes easy to bond due to residual heat after processing (so-called blocking occurs). Further, when winding after printing, the contact area increases from the printing surface to the opposite surface (the inner surface side of the paper container), so that the ink is easily transferred.

[Fuzzing rate]
In many cases, bubbles remain in the contents, particularly in the vicinity of the body joint 4. For this reason, it is possible to further increase the effect of preventing bubbles from remaining in the contents by reducing the fluffing rate, which is the degree of fluffing of the end surface 4a on the inner surface side of the body joint portion 4.

As one of the reasons why the remaining bubbles are often generated in the vicinity of the body joint 4, when air flows into the container from the outside of the container due to decompression inside the container, the body joint 4 and the bottom plate 2 It is conceivable that air is likely to flow in from the vicinity of the joint portion. After the contents containing the thickener, gelling agent or coagulant are filled at a temperature of room temperature or higher, the lid is sealed and refrigerated, whereby the inside of the container is in a reduced pressure state.
The air that has flowed into the container becomes bubbles and first comes into contact with the end surface 4a on the inner surface side of the body joint 4. If the end face 4a on the inner surface side of the body joint part 4 is smooth and has less fuzz, the contact area with the bubbles is small, so that the bubbles are easily released and the bubbles are released before the contents are cooled and solidified. Since it escapes from the liquid surface, it becomes difficult for bubbles to be mixed into the liquid surface of the contents.
On the other hand, when the paperboard is punched, the cutting of the blade is not good, and if the end surface 4a on the inner surface side of the body joint portion 4 is uneven and fluffy, the contact area with the air bubbles is large, so that the air bubbles are difficult to separate, and the contents Since the air bubbles are released after the container is cooled and the inside of the container is decompressed, the air bubbles are solidified before they rise in the contents and escape from the liquid level of the contents. .

(Measurement of fluff rate)
In the present specification, the “fluff rate” of the end face of the body joint is defined by the following definition.
First, the definition of the fluff portion will be described with reference to FIG. FIG. 5 schematically shows the state of fluffing at the end face of the body joint portion. The line connecting the valleys of the end faces of the trunk joint portion is defined as the base line. It is considered that the baseline substantially coincides with the cut end face of the paper material constituting the body portion. A straight line is drawn parallel to the base line at a position 15 μm away from the base line, and the length Y at which the straight line intersects with the fluff is measured. As shown in FIG. 5, when the fluff is in a lump shape, the length Y may be measured for each lump. On the end face of the trunk joint shown in FIG. 5, the length Y is obtained as follows.

  When the length of the measured end face is X, the fluffing rate of the end face of the body joint is defined as follows. In addition, it is preferable that the length X of the measured end surface is 30 mm or more.

  The fuzzing rate at the end face of the trunk joint is preferably 30% or less, more preferably 20% or less, and even more preferably 10% or less.

[Bubble rise]
In the paper container 10 of the present embodiment, the end surface 4a of the body joint part 4 on the inner surface side of the paper container 10 in a state where the body joint part 4 on the inner surface side of the paper container 10 is vertically arranged in water. It is preferable that the time required for the bubbles to rise by 30 mm along the inner surface side resin layer 7 is 40 seconds or less, and 30 seconds or less It is more preferable that it is 20 seconds or less.
Further, the paper container 10 of the present embodiment is configured so that the inner surface side of the body joint portion 4 on the inner surface side of the paper container 10 is vertically arranged in water. When the rising speed of 0.18 mL bubbles adhering adjacent to the end face 4a is measured, the speed at which the bubbles rise along the inner surface side resin layer 7 is preferably 0.75 mm / second or more. / Second or more is more preferable, and 20 mm / second or more is further preferable.
FIG. 4 is a schematic diagram for explaining the state of the bubbles 9 adhering adjacent to the end surface 4 a of the body joint portion 4 on the inner surface side of the paper container 10.

  In consideration of the fact that bubbles often remain in the contents, particularly in the vicinity of the trunk joint 4, the measurement conditions for the rise of the above-mentioned bubbles are set adjacent to the end face 4 a of the trunk joint 4. The rise of the attached bubble 9 is determined. In the paper container satisfying the above-mentioned regulations relating to the rise of bubbles, the effect of preventing bubbles from remaining is further enhanced.

(Measurement of bubble rise time)
When the trunk joint is disposed vertically in water (parallel to the direction of gravity), the time required for the 0.18 mL bubbles adhering adjacent to the end face of the trunk joint to rise along the resin layer is It can be obtained as follows.
The measurement is performed in a room controlled at a room temperature of 23 ° C. and a humidity of 50%. By leaving a water bath containing distilled water in a room controlled at a room temperature of 23 ° C. and a relative humidity of 50% for 24 hours or more, the water temperature becomes 22.5 ° C. The trunk joint formed on the inner surface side of the paper container is submerged in water. Although the entire paper container may be submerged in water, the measurement is performed using the body joint formed on the inner surface side of the paper container, so that the body joint is included so that the measurement can be performed more easily. It is good to cut out a part of trunk | drum from a paper container, and use this for a measurement. In that case, it is good to cut off so that the length of a trunk | drum junction part may be set to 30 mm. If the length of the body joint part is not cut so as to be 30 mm, the upper end and the lower end should be perpendicular to the body joint part so that the distance between the upper end and the lower end of the body joint part is 30 mm. Draw a line.
0.18 mL of air is measured in a room with a room temperature of 23 ° C. and a relative humidity of 50%, and 0.18 mL of air bubbles are adhered adjacent to the inner end face of the trunk joint submerged in water. For example, a known device such as a micropipette capable of discharging a substance whose volume is quantified can be prepared. After the tip of the micropipette tip was placed in a portion adjacent to the end surface of the body joint portion, 0.19 mL of air bubbles quantified to 0.18 mL were ejected to adhere to the end surface of the body joint portion. 18 mL bubbles can be prepared. The water depth when adhering bubbles adjacent to the end face of the trunk joint is in the range of 100 to 110 mm, and then the bubbles rise 30 mm along the thermoplastic resin laminate surface from the position of the water depth 100 mm (water depth 70 mm). Measure the time it takes to complete. When the bubbles are discharged, the trunk joint portion does not necessarily have to be arranged vertically in water. After the bubble is attached adjacent to the end face of the body joint, the body joint is placed vertically, and the time for the bubble to rise along the resin layer is measured from when the body joint is placed vertically. The time required for the bubbles to rise may be used.
When measuring the time required for bubbles to rise, by making constant the temperature and humidity when measuring 0.18 mL of air, the water temperature in the water tank, and the water depth at which bubbles are attached and start rising, Since the volume of bubbles to be adhered can be made constant, measurement can be performed under constant conditions.
In addition, even if the speed at which the bubbles rise is not constant, it may be calculated as the time required for the bubbles to rise. The following two patterns are given as examples of patterns in which the rate at which bubbles rise is not constant.
1. Ascending and stopping repeatedly Example) If air bubbles adhere to the resin layer of the base material, it will not move for a while. Repeatedly "starts moving a little and stops immediately, then starts moving a little later and stops immediately".
2. Ascending while accelerating Example) After attaching a bubble, after moving for a short time, if it starts to move a little, it will rise while accelerating at once.

[Contact angle with water]
In the paper container 10 of the present embodiment, the contact angle between the inner surface side resin layer 7 on the inner surface side of the body and water is preferably 60 degrees or greater and 98 degrees or less, and more preferably 70 degrees or greater and 96 degrees or less. Preferably, it is 75 degrees or more and 93 degrees or less, and it is especially preferable that it is 80 degrees or more and 85 degrees or less.
The contact angle with water is an index representing the wettability of the inner surface side resin layer 7 to water. The higher the wettability of the inner surface side resin layer 7, the higher the effect of preventing the adhesion of bubbles to the inner surface side resin layer 7 and the early removal. On the other hand, if the wettability of the inner surface side resin layer 7 is too high, the contents easily permeate from the end surface of the body joint portion, leading to leakage and deterioration of the appearance. Therefore, the wettability of the inner surface side resin layer 7 is preferably in the above range. When the contact angle between the inner surface side resin layer 7 on the inner surface side of the trunk portion and water is in the above range, both the effect of preventing the adhesion of bubbles and the effect of early removal can be achieved, and the product quality can be improved.

(Measurement of contact angle with water)
The contact angle between the resin layer and water can be measured using, for example, an automatic contact angle meter DMs-400 (manufactured by Kyowa Interface Science Co., Ltd.). Even when other measurement devices are used, the contact angle can be measured using a device that can be measured by the same principle.
As test conditions, contact angles under the following conditions are obtained.
Measurement environment: 23 ° C, 50% RH
Measuring method: θ / 2 method, distilled water is dropped onto a 2 μL test piece, and the contact angle after 1 msec is measured.

[Sealing of paper containers]
As described in the above stage of [Fuzzing rate], it is considered that the air flowing into the container from the outside of the container due to the decompression of the inside of the container is the source of bubbles. From this, it is possible to further enhance the effect of preventing bubbles from remaining in the contents by increasing the sealing property of the paper container.

(Sealing method)
The sealing property of the paper container can be measured as follows. First, a lid is sealed on the paper container to seal the inside of the paper container. The paper container sealed with the lid is submerged in water at a water temperature of 22.5 ° C., and 5 mL / min of air is sent inside the paper container in a room controlled at a room temperature of 23 ° C. and a relative humidity of 50%. An air pump or the like to which an air injection needle is connected may be used to send in air. In 15 minutes, 25 mL of air is sent into the paper container, and the volume of air leaking from the paper container is measured.

The volume of air leaked from the paper container in 15 minutes, determined by the above-mentioned sealing property measurement method, is preferably 3.0 mL or less, more preferably 2.6 mL or less, and 2.3 mL or less. More preferably it is.
Because the airtightness of the joint of the paper container is at the above value, even if decompression occurs in the paper container after filling and cooling the contents, it is difficult for air to flow in from the outside of the paper container. It is possible to more effectively suppress the mixing of bubbles into the contents derived from the inflow of air from the outside of the container.

[lubricant]
In the paper container 10 of the present embodiment, even if the lubricant is attached to at least a part of the outer surface side of the body part, or the lubricant is attached to at least a part of the inner surface side of the body part. Good. The method for attaching the lubricant to the barrel is not particularly limited. However, in the manufacture of a general paper container, when joining the body and the bottom plate (the bottom edge of the body is folded inward, and the disk-shaped periphery is fixed so as to wrap the periphery of the bottom plate When a bottom curl is formed), a lubricant may be applied to the lower outer peripheral surface of the body portion. Also, when the top curl is formed outwardly by bending the top edge of the body of the paper container and the top curl is formed in the opening, a lubricant is applied to the upper inner peripheral surface of the body. Yes. Thus, the lubricant may be applied to the paper container when forming the bottom curl or the top curl as described above.

In the paper container with lubricant applied to the lower outer peripheral surface of the body part, the paper container is stacked when it is put into the case as a manufacturing process or product, and contacts the inner surface side of the paper container below it Then, the lubricant is transferred. Then, when the paper containers are pulled out from the stack, the transferred lubricant is rubbed and spreads wet on the inner surface side of the paper containers.
In a paper container with a lubricant coated on the upper inner peripheral surface of the body part, the paper container is stacked when it is put into a case as a manufacturing process or product, and on the outer surface side of the paper container above it The lubricant that comes into contact and adheres to the upper inner peripheral surface is rubbed and wetted and spread below the inner surface of the paper container.
In the inner surface side resin layer 7 provided in the paper container 10 of the present embodiment, the surface roughness is set to 0.4 μm or more and less than 1.5 μm, which is smaller than the conventional paper container. Since there are few irregularities and the specific surface area is small, even if a small amount of lubricant is applied to the paper container 10, it tends to rub against the inner surface of the container and spread.

  Among the lubricants, liquid paraffin or silicone lubricant is preferably used from the viewpoints of operability, cost, quality, and the like. As the lubricant, it is preferable to use substances described in a table (positive list) of substances that can be used for containers and packaging of “voluntary standards for food packaging made of synthetic resin such as polyolefin”. Listed in the positive list and can be used as lubricants include food grades of food paraffin that have passed the standards for food additives (for example, High Call K series manufactured by Kaneda Corporation), grades for food packaging containers Silicone-based lubricants (for example, Shin-Etsu Silicone KF, KM series manufactured by Shin-Etsu Chemical Co., Ltd., TPR series manufactured by Momentive Performance Materials Japan GK).

  The liquid paraffin is not particularly limited as long as the above is satisfied, but the average molecular weight is preferably 198 (carbon number 14) or more and 618 (carbon number 44) or less. Since the average molecular weight is 198 or more, the deterioration of the lubrication performance due to the viscosity becoming too low does not occur, and the risk of deterioration of the working environment, ignition, ignition, etc. due to the too high volatility is kept low. it can. Since the viscosity does not become too high because the average molecular weight is 618 or less, the handling at the operation is easy, and the shine on the coated portion can be kept low.

Examples of silicone-based lubricants include methylhydrodiene polysiloxane (viscosity at 20 ° C. of at least 100 cSt is preferred), dimethyl polysiloxane (viscosity at 20 ° C. of at least 100 cSt, application amount of 600 mg / m ² or less is preferred), methylphenyl polysiloxane ( Viscosity at 20 ° C. Minimum of 100 cSt, coating amount of 600 mg / m ² or less is preferable, polyoxyalkylene (2 to 4 carbon atoms) dimethylpolysiloxane (addition amount of 0.3% by mass or less is preferable), polyoxyethylene grafted poly Dimethylpolysiloxane (addition amount 0.3 mass% or less, preferably used at 100 ° C. or less), linear or branched organopolysiloxane having an alkyl group (C1-C32) on a silicon atom (addition amount) 0.75% by mass or less, preferably 70 ° C. or less) Or more than one type.

[Food additive]
The paper container is preferably formed by attaching a food additive to at least a part of the inner surface side of the body portion. By adhering the food additive, even when food is filled in the paper container 10, the hydrophilicity on the inner side of the paper container can be increased while maintaining high safety.
When a lubricant adheres to at least a part of the inner surface side of the trunk part, the lubricant contains a food additive, so that a food additive is present on at least a part of the inner surface side of the trunk part. It may be attached. By including the food additive in the lubricant, it becomes more efficient than applying the food additive and the lubricant to the paper container in a separate process, and even when the food is filled inside the paper container 10, it is high. The hydrophilicity of the inner side of the paper container can be increased while maintaining safety. The lubricant can be transferred to the inner side of the paper container by stacking the paper containers, and can be spread out.
Since the air bubbles are hydrophobic, the air bubbles are easily attached to the surface of the hydrophobic inner surface side resin layer 7 and are not easily detached. If the state in which bubbles are attached to the inner surface side resin layer 7 is likely to occur, the state in which the content filled in the paper container is solidifying or the bubbles attached to the inner surface side resin layer 7 gradually become liquid of the content. It tends to float to the surface and bubbles remain on the liquid surface of the contents. Therefore, by attaching the food additive together with the lubricant to the inner surface side, the hydrophilicity on the inner surface side can be increased, and the risk that bubbles remain in the contents filled in the paper container can be reduced.

  When a lubricant is attached to at least a part of the inner surface side of the trunk part, the inner surface side resin layer contains a food additive, whereby a food additive is added to at least a part of the inner surface side of the trunk part. An object may be attached.

  In the inner surface side resin layer 7 provided in the paper container 10 of the present embodiment, the surface roughness is set to 0.4 μm or more and less than 1.5 μm, which is smaller than the conventional paper container. There are few irregularities and the specific surface area is small. Therefore, even if the amount of the lubricant and the food additive applied to the paper container 10 is small, the mixture tends to rub against the inner surface of the container and spread.

  The food additive to be mixed with the lubricant is not particularly limited as long as it is a component that does not cause a safety problem even when directly in contact with food. More specifically, it is preferably a compound listed in a food additive official document issued by the Ministry of Health, Labor and Welfare. Furthermore, among food additives, the standard for use (foods that can be used and used in the food additive official document) It is preferable that the substance does not have restrictions on the maximum amount and limit of use. Examples of food additives that are not regulated by the above usage standards include glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, propylene glycol fatty acid ester, and lecithin. Since there is no safety problem even when the food additive is transferred to food, the paper container 10 coated with the lubricant containing the food additive has high safety and is suitable as a food packaging container. .

The HLB value is used as a value representing the degree of affinity between water and oil (an organic compound insoluble in water). The HLB value ranges from 0 to 20, but the closer to 0, the higher the lipophilicity and the closer to 20, the higher the hydrophilicity. Several calculation methods have been proposed. In the present specification, values calculated by the atlas method are adopted.
Atlas method: The saponification value is S, the acid value of the fatty acid is A, and the HLB value is defined as 20 × (1-S / A).
The acid value is one of the numerical values that are used as an index for refining and altering fats and oils, and is defined as “the number of mg of potassium hydroxide necessary to neutralize free fatty acids present in 1 g of fats and oils”. Is adopted.
When a mixture of a plurality of types of food additives having different HLB values is used, the HLB value of the mixture is calculated as a weighted average value thereof.

Regarding the stability after mixing the lubricant and the food additive, it is preferable that the HLB value of the food additive is within a predetermined range. From the viewpoint of further improving the hydrophilicity of the inner side of the paper container, the HLB value of the food additive is preferably 1 or more, and more preferably 5 or more. When the food additive is contained in the thermoplastic resin, the HLB value of the food additive is preferably 1 or more and 10 or less. When the food additive is contained in the lubricant and liquid paraffin or a silicone-based lubricant is used as the lubricant, if the food additive has an HLB value of 3 or more and 17 or less, the miscibility is good and separation does not occur. Here, “good miscibility” refers to a state in which the mixture is cloudy but does not separate. If the HLB value is too high or too low than the above range, separation may occur without mixing with the lubricant. From the viewpoint of further improving the hydrophilicity on the inner side of the paper container, the HLB value of the food additive is more preferably 5 or more.
From the above viewpoint, the food additive preferably has an HLB value of 1 or more and 17 or less. When the food additive is contained in the lubricant, the HLB value of the food additive is preferably 3 or more and 17 or less, more preferably 5 or more and 17 or less, and 6 or more and 16 or less. Further preferred.

  As food additives having an HLB of 5 to 17, glycerol monocaprylate, glycerol monocaprate, glycerol monolaurate, diglycerol laurate, diglycerol stearate, diglycerol oleate, diglycerol laurate, diglycerol myristate, Tetraglycerin stearate, decaglycerin laurate, decaglycerin stearate, decaglycerin oleate, sorbitan laurate, sorbitan palmitate, sorbitan stearate, sorbitan caprylate, sucrose stearate (monoester content 30% to 80% Sucrose palmitate (monoester content 30% to 80%), sucrose myristylate (monoester content 30% to 80%), sucrose ole Phosphate ester (80 percent monoester content of 30% or more), such as sucrose laurate ester (monoester content of 80% or less than 30%) can be mentioned. As lecithin, any of plant lecithin, fractionated lecithin, egg yolk lecithin, enzyme-treated lecithin, and enzyme-decomposed lecithin can be used.

In the paper container of the present invention, it is preferable that 0.0005 mg / piece or more and 1.5 mg / piece or less of the food additive is attached to the inner surface side of the body portion, and 0.001 mg / piece or more and 1 mg / piece or less is attached. More preferably, it is more preferably 0.01 mg / piece or more and 0.5 mg / piece or less.
The paper container, it is preferable that the food additive is attached at 0.005 / cm ² or more 17μg / cm ² or less on the inner surface of the barrel, 0.01 [mu] g / cm ² or more 10 [mu] g / cm ² or less is more preferably formed by adhering in, it is more preferably formed by adhering at 0.1 [mu] g / cm ² or more 5.5μg / cm ² or less. By adhering the food additive in the above range, the effect of enhancing the hydrophilicity more effectively is exhibited, and the content hardly permeates from the end face of the trunk joint portion. In addition, when a trunk | drum has a top curl part, the inner surface side of a trunk | drum shall contain the part originating in the trunk | drum part among top curl parts. Moreover, the adhesion amount of the food additive per unit area on the inner surface side of the body portion is obtained as an average value in the area on the inner surface side of the body portion.
In the paper container of the present invention, it is preferable that 0.0005 mg / piece or more and 1.5 mg / piece or less of the food additive is adhered to the outer surface side of the body portion.

  When the lubricant contains a food additive, the amount of the lubricant containing the food additive may be appropriately determined according to the preferred amount of the food additive adhering to the inner surface side of the trunk as described above. The content of the food additive with respect to the lubricant is not particularly limited, but it is preferable that the food additive is contained at a ratio of 0.01% by weight or more and 10% by weight or less per lubricant. More preferably, the food additive is contained at a ratio of 0.1 wt% to 10 wt% per agent, and the food additive is contained at a ratio of 0.3 wt% to 7 wt% per lubricant. More preferably. When the content of the food additive is 0.01% by weight or more, the effect of increasing hydrophilicity is effectively exhibited. When the content rate of the food additive is 10% by weight or less, the content hardly permeates from the end face of the trunk joint portion. Further, when the content of the food additive with respect to the lubricant is in the range of 0.01 wt% or more and 10 wt% or less, the lubricating performance is not hindered.

The paper container has a lubricant adhering to a lower outer peripheral surface which is within 2 cm from the lowermost part on the outer surface side of the body part, the lubricant contains a food additive, and the food additive is added to the lower outer peripheral surface. it is preferable that the object is attached at 0.005 / cm ² or more 17μg / cm ² or less, and more preferably formed by adhering at 0.01 [mu] g / cm ² or more 10 [mu] g / cm ² or less, 0.1 [mu] g / cm it is more preferably formed by adhering at least ^two 5.5μg / cm ² or less. The method of attaching the lubricant to the lower outer peripheral surface is not particularly limited, but when joining the trunk and the bottom plate, that is, by folding the lower end edge of the trunk inward and bending the disc-shaped periphery, the periphery of the bottom plate When forming the bottom curl to be fixed so as to include the lubricant, the lubricant may be applied to the lower outer peripheral surface of the body portion and adhered to the lower outer peripheral surface. When a trunk | drum has a bottom curl part, the outer surface side of a trunk | drum shall include the part originating in the trunk | drum outer part among bottom curl parts. Moreover, the amount of food additive attached per unit area of the lower outer peripheral surface of the trunk is determined as an average value on the upper and lower outer peripheral surfaces of the trunk.

The paper container has a lubricant adhering to an upper inner peripheral surface within a range of 2 cm from the uppermost part on the inner surface side of the body part, the lubricant contains a food additive, and the upper inner peripheral surface it is preferable that the food additive is attached at 0.005 / cm ² or more 17μg / cm ² or less, and more preferably formed by adhering at 0.01 [mu] g / cm ² or more 10 [mu] g / cm ² or less, 0.1 [mu] g More preferably, it adheres at / cm ² or more and 5.5 μg / cm ² or less. The method of attaching the lubricant to the upper inner peripheral surface is not particularly limited, but when the top curl is bent outward to form a top curl in the opening, the lubricant is applied to the upper inner periphery of the barrel. It can be exemplified by coating on the surface and adhering to the upper inner peripheral surface. When a trunk | drum has a top curl part, the inner surface side of a trunk | drum shall include the part originating in a trunk | drum part among top curl parts. Further, the amount of food additive attached per unit area of the upper inner peripheral surface of the trunk is obtained as an average value on the upper inner peripheral surface of the trunk.

<Contents to fill the paper container>
The content to be filled in the paper container is preferably a content containing a thickener, a gelling agent or a coagulant. Examples of such contents include yogurt, jelly, pudding, bavaria, mousse, agar, jam, ice cream, tofu, konjac and the like.
Examples of the gelling agent include gelatin, collagen, agar, carrageenan, and pectin, which have a property of solidifying when cooled.
Examples of the thickener include polysaccharides such as carboxymethylcellulose, xanthan gum, locust bean gum, guar gum, pectin, sodium alginate, glucomannan, cellulose, hemicellulose, and starches.
There are mainly coagulants for tofu and konjak. Coagulants for tofu include calcium chloride, magnesium chloride, crude seawater magnesium chloride (garlic), calcium sulfate, magnesium sulfate, glucono delta lactone. Etc. Examples of the coagulant for konjac include calcium hydroxide, calcined calcium, which is also called slaked lime.

Yogurt is obtained by fermenting raw milk such as cow milk with lactic acid bacteria, but the production method differs depending on the type. There are two types: a pre-fermentation type (such as drink yogurt or soft yogurt) in which the raw material is fermented in a tank and filled in a container, and a post-fermentation type (such as plain yogurt) in which the raw material is fermented after filling in the container.
In the post-fermentation type, raw materials are mixed, sterilized, a starter (lactic acid bacteria, etc.) is added, and then the container is filled immediately and fermented in the container. The pre-fermentation type is the same process as the post-fermentation type from mixing of raw materials to sterilization and addition of a starter (lactic acid bacteria, etc.), and then fermenting in a tank before filling the container.

The paper container of this embodiment is applicable to both pre-fermentation type yogurt and post-fermentation type yogurt, but is preferably applied to pre-fermentation type yogurt.
In the post-fermentation type, bubbles (carbon dioxide) are generated by fermentation, and the acidity increases, so the viscosity of yogurt increases.
On the other hand, in the pre-fermentation type, fermentation → cooling → filling (filling a mixture of yogurt fermented in a tank with sweeteners, fruit juice, and pulp and capping) or fermentation → filling → cooling. Therefore, almost no bubbles are generated by fermentation. If the air bubbles mixed at the time of filling are quickly removed before the viscosity rises due to solidification of gelatin, agar, etc. by cooling and standing after filling, no air bubbles or cracks are generated on the yogurt surface after cooling.

  In a paper container with a rising rate of bubbles adhering to the inner surface, it is possible for bubbles to quickly escape from the filling before the viscosity increases due to solidification of gelatin, agar, etc. due to cooling and standing after filling. For this reason, the risk of bubbles and cracks occurring on the surface of the filling after cooling is reduced.

<Method for manufacturing paper container>
[Formation of paper container body]
The paper container main body can be manufactured as follows, for example.
A resin for forming the inner surface side resin layer 7 is laminated on the inner surface side of the paper substrate 6 by a melt extrusion method (resin laminating process), and a resin for forming the outer surface side resin layer 8 on the outer surface side of the paper substrate 6 is melt extruded. The processed paper 5 is obtained by laminating (resin laminating) by the method.
If necessary, a thermoplastic resin may be laminated on the outer surface side by a melt extrusion method in order to prevent a decrease in rigidity due to condensation.
Immediately after the thermoplastic resin is laminated (resin laminating) on the paper substrate by the melt extrusion method, the thermoplastic resin layer is pressure-bonded to a metal cooling roll and rapidly cooled. At that time, it is applied to the surface of the cooling roll. The unevenness is transferred to the surface of the thermoplastic resin laminate layer, and the unevenness is imparted to the thermoplastic resin laminate layer. By adjusting the surface roughness of the metal cooling roll, the surface roughness (Ra) of the resin laminate layer can be set to 0.4 μm or more and less than 1.5 μm.
The obtained processed paper 5 is punched out to form a trunk blank (not shown). Similarly, the processed paper 5 is punched to form a bottom plate blank (not shown). By polishing the punching die and maintaining a sharp state, the fluffing rate, which is the degree of fluffing on the inner end face of the body joint portion, can be lowered. This also makes it possible to further enhance the effect of preventing bubbles from remaining in the contents.

  The body part blanks thus formed are overlapped and bonded together by heat sealing to form the body part 2, and the bottom plate part blank is joined to the bottom part of the body part 1 to form the bottom plate part 2. Thus, the container body 3 is formed.

[Join the body and bottom plate]
In the method for manufacturing a paper container of the present invention, the body portion and the bottom plate portion are bonded by an expansion sealing method. There are two methods for joining the body portion and the bottom plate portion: an expander roll method and an expansion sealing method. A diagram for explaining these methods is shown in FIG.
In the expander roll method, a disk-shaped mold (roller) is eccentrically rotated and pressed (FIG. 6a). However, if the pressure of the crimping is increased in order to improve the sealing property of the container, the bottom paper is instantaneously strongly pulled in one direction by the roller, wrinkles are likely to occur near the circumference of the bottom, and the appearance deteriorates. The problem that occurs easily.
In the expansion sealing method, four locations are simultaneously crimped on the surface (FIGS. 6b to 6c). FIG. 6c shows a state in which the entire bottom portion is pressure-bonded by shifting the second station by shifting by 45 °. In the expansion sealing method, it is possible to obtain the same hermeticity of the container as the expander roll method without generating wrinkles in the vicinity of the circumferential portion of the bottom.

(Paper substrate)
The paper base used in the body and bottom plate that make up the container body consists of chemical pulp or mechanical pulp obtained from non-wood such as wood, kenaf, bamboo, etc., and must be made by normal paper making processes. However, it is not limited to this.
Among them, it is preferable to use chemical pulp. By using chemical pulp, the rigidity is increased even with the same basis weight compared to when mechanical pulp is used, and yellowing is suppressed when exposed to light for a long time or stored at a high temperature for a long time. In addition, since the strength and elongation at break are further increased, it is difficult to break when a top curl is applied during cup molding. The blending ratio of the chemical pulp in the paper substrate is preferably 80% by weight or more, more preferably 90% by weight or more, and most preferably 95% by weight or more.
The basis weight of the paper base material (base paper) before the resin laminating process is preferably 150 g / m ² or more. If the basis weight is 150 g / m ² or more, the strength and rigidity of the paper container will increase, so there is a risk of destruction or deformation due to factors such as dropping, stacking, vibration during transportation, acceleration, etc. when the contents are filled. There is no. There is also an advantage that the container filled with the contents is easy to hold because the deformation is small when the container is held by hand.
In addition, as for the basic weight of the paper base material (base paper) before performing a resin lamination process, 350 g / m < ² > or less is preferable. By setting the basis weight to 350 g / m ² or less, the strength and rigidity of the container do not become excessive (overspec), and the manufacturing cost does not increase and it does not become uneconomical.

  Since the paper substrate needs to be stretched without being broken in a direction perpendicular to the paper making direction by top curl processing, the elongation at break in the direction perpendicular to the paper making direction is preferably 3% or more, preferably 4% or more. It is more preferable that it is 5% or more. For this purpose, the water content is preferably 5 to 9% by weight, more preferably 6 to 8% by weight. When the water content is 9% by weight or less, the rigidity of the paper container is not too low, and when it is 5% by weight or more, the elongation at break increases.

The density of the paper substrate is preferably 0.7 g / cm ³ or more and 1.0 g / cm ³ or less. When the density of the paper base material is 0.7 g / cm ³ or more, the strength and elongation at break increase, so that the top curl is difficult to break during cup molding. If the density of the paper substrate exceeds 1.0 g / cm ³ , the thickness per certain basis weight becomes thin, so that the rigidity becomes low, which is not preferable.

  The freeness (CSF) of the pulp for producing the paper substrate is preferably 200 to 500 mL, and more preferably 300 to 450 mL. In the case of 500 mL or less, the strength and breaking elongation of the paper base material are not too low, which is preferable. A freeness of 200 mL or more is preferable because the density of the paper substrate does not become too low.

(Resin layer thickness)
The thickness of the resin layer is preferably 20 μm or more. When the thickness of the resin layer is 20 μm or more, the base paper is more reliably covered with the resin layer, there is no possibility of occurrence of a defective coating portion (so-called pinhole), and the sealing property and airtightness of the heat-sealed joint portion And the adhesion between the base paper and the resin layer can be further improved.
The thickness of the resin layer is preferably 60 μm or less. If the thickness of the resin layer exceeds 60 μm, the coverage of the base paper by the resin layer, the sealing and airtightness of the heat-sealed joint, and the adhesiveness between the base paper and the resin layer are not improved any more, and the manufacturing cost Is expensive.

EXAMPLES Next, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited to a following example.
<Example 1>
Low-density polyethylene (on the inner surface side of the container) on one side (container inner side) of a paper substrate having a basis weight of 280 g / m ² (thickness 290 μm, chemical pulp 100%, pulp drainage (CSF) 400 ml, moisture content 7.0%). Tosoh Corporation brand name: Petrocene P204, density 0.922 g / cm ³ ) was extruded and laminated at a thickness of 40 μm by melt extrusion. The surface roughness (Ra) of the low density polyethylene laminate surface was 0.60 μm.
Low density polyethylene (brand name: Petrocene P204 manufactured by Tosoh Corporation, density 0.922 g / cm ³ ) is extruded and laminated at a thickness of 20 μm by melt extrusion on the opposite side (outer side of the container) of the paper substrate. The processed paper A for members was obtained. The surface roughness (Ra) was 0.40 μm.
In the winding after laminating, no sticking (blocking) of the paper material occurred.
When oil-based gravure printing was performed on the base paper after lamination, no ink was transferred inside the winding.
After the punching die was polished to a sharp state, the container barrel member blank was punched from the barrel member processed paper A.
Next, low-density polyethylene (brand name: Petrocene P204, density 0.922 g / cm ³ manufactured by Tosoh Corporation) on one side (inner side of the container) of the same paper base material used for the body member having a basis weight of 300 g / m ² Was extruded and laminated to a thickness of 40 μm. The surface roughness (Ra) of the low density polyethylene laminate surface was 0.60 μm.
Low-density polyethylene (brand name: Petrocene P204, density 0.922 g / cm ³ ) manufactured by Tosoh Corporation is extruded and laminated at a thickness of 20 μm on the opposite side (outer side of the container) of the paper substrate by the melt extrusion method, and the bottom part The processed paper B for materials was obtained.
A container bottom member blank was punched from the bottom member processed paper B.
The container body member blank and the container bottom member blank were integrated by a cup molding machine to assemble a paper container. A specific method is shown below.
(1) One end edge and the other end edge of the body member blank were overlapped and joined. When one edge of the body member blank and the other edge were overlapped and joined, at least the edge of the inner surface side resin layer was heated by applying hot air and then the edges were overlapped and pressure bonded.
(2) A tray-shaped bottom member having a circular plate-shaped peripheral edge bent was attached to the inner surface of the lower part of the truncated cone-shaped cylinder tapering downward.
(3) The lower end edge of the cylindrical body was bent inward to form a bottom curl that was fixed so as to wrap around the periphery of the tray-like bottom member. When forming the bottom curl, 2.5 mg / piece of liquid paraffin (product name: High Coal K290, manufactured by Kaneda Corporation) was applied as a lubricant to the lower outer peripheral surface of the cylinder.
(4) The container body member blank and the container bottom member blank were heat-bonded by applying a pressure of 12 kgf / cm ² to the crimping of the body member and the bottom member by an expansion sealing method (see FIG. 7).
(5) The end edge of the cylindrical body was bent outward to form a top curl in the opening, thereby completing a paper container. At the time of forming the top curl, 2.5 mg / piece of liquid paraffin (product name: High Coal K290, manufactured by Kaneda Corporation) was applied as a lubricant to the upper inner peripheral surface of the cylindrical body.
The dimensions of the paper container obtained in Example 1 were a brim outer diameter of 71 mm, a cup height of 45 mm, a full capacity of 106 ml, and an area of the inner surface of the paper container body of 92.7 cm ² .

<Example 2>
A paper container of Example 2 was manufactured in the same manner as in Example 1 except that the surface roughness (Ra) of the low density polyethylene laminate surface on the inner surface side of the processed paper A for trunk members was 1.30 μm.
<Example 3>
Example 1 except that the container body member blank is punched from the body member processed paper A with the blade of the punching die slightly worn, and the fluffing rate of the inner surface side end surface of the body member joint is 23%. Similarly, the paper container of Example 3 was manufactured.
<Example 4>
The paper of Example 4 was used in the same manner as in Example 1 except that the container body member blank and the container bottom member blank were heat-bonded by applying a pressure of 9 kgf / cm ² to the crimping of the body member and the bottom member by an expansion sealing method. A container was made.
<Example 5>
The paper container of Example 5 was changed in the same manner as in Example 1 except that the type of lubricant was changed to a silicone-based lubricant (product name: DOW CORNING TORAY SH 200 C FLUID 100 CS manufactured by Toray Dow Corning Co., Ltd.). Manufactured.
<Example 6>
The same as in Example 1 except that the concentration of the food additive (product name: Poem J-0381V, manufactured by Riken Vitamin Co., Ltd., ingredient: decaglycerin oleate, HLB value 12.0) in the lubricant was 1% by weight. The paper container of Example 6 was manufactured.
<Example 7>
Example as in Example 1 except that the concentration of the food additive (product name: Richemal L250A, manufactured by Riken Vitamin Co., Ltd., ingredient: sorbitan laurate, HLB value 7.4) in the lubricant was 1% by weight. Seven paper containers were produced.
<Example 8>
The same as in Example 1 except that the concentration of the food additive in the lubricant (Riken Vitamin Co., Ltd., product name: Poem J-0021, component: decaglycerin laurate, HLB value 15.5) was 1% by weight. Thus, a paper container of Example 8 was produced.
<Example 9>
The same as in Example 1 except that the concentration of the food additive (product name: Poem J-0381V, manufactured by Riken Vitamin Co., Ltd., ingredient: decaglycerin oleate, HLB value 12.0) in the lubricant was 5% by weight. The paper container of Example 9 was manufactured.
<Example 10>
Example 1 except that the concentration of the food additive in the lubricant (product name: Poem J-0381V, manufactured by Riken Vitamin Co., Ltd., component: decaglycerin oleate, HLB value 12.0) was 0.5% by weight. Thus, a paper container of Example 10 was produced.
<Example 11>
The container body member blank and the container bottom member blank were made of the paper of Example 11 in the same manner as in Example 1 except that the body member and the bottom member were bonded to each other by applying a load of 450 kgf to the expander roller. A container was manufactured.

<Comparative Example 1>
A paper container of Comparative Example 1 was produced in the same manner as Example 1 except that the surface roughness (Ra) of the low density polyethylene laminate surface on the inner surface side of the processed paper A for trunk members was 0.30 μm.
<Comparative example 2>
A paper container of Comparative Example 2 was manufactured in the same manner as in Example 1 except that the surface roughness (Ra) of the low density polyethylene laminate surface on the inner surface side of the processed paper A for trunk members was 3.1 μm.

<Evaluation of paper containers>
[Measurement of surface roughness]
The surface roughness of the inner surface side resin layer was measured under the following conditions using the following equipment.
Measuring instrument: Surfcoder SE4000 (stylus type surface roughness measuring instrument) manufactured by Kosaka Laboratory Ltd.
Measurement length: 2.5 mm, measurement speed: 0.5 mm / s

[Measurement of time required for bubble rise]
By leaving a water bath containing distilled water in a room controlled at a room temperature of 23 ° C. and a relative humidity of 50% for 24 hours or more, the water temperature becomes 22.5 ° C. The measurement was performed in a room controlled at a room temperature of 23 ° C. and a humidity of 50%. Cut out the body of the paper container, attach the outer surface of the body to a smooth plastic plate, collect 0.18 mL of air with a micropipette in a room at 23 ° C and 50% relative humidity, and submerge it in water. Air bubbles were allowed to adhere within a range of water depth of 100 to 110 mm adjacent to the end surface of the body portion joining portion inner surface of the thermoplastic resin laminated surface of the body portion. After submerging in the water tank, the plastic plate was erected vertically, and the time required for the bubbles to rise 30 mm along the thermoplastic resin laminate surface from the position where the water depth was 100 mm (water depth 70 mm) was measured.

[Measurement of contact angle with water]
The measurement of the contact angle between the inner resin layer and water was performed as described above (Measurement of contact angle with water). In addition, in order to measure the influence on the value of the contact angle by the lubricant (silicone oil) used at the time of molding the paper container on the inner surface side resin layer after the paper container molding, For the container, the measurement was performed with the lubricant containing the food additive adhered to the inner surface side resin layer.

[Measurement of fluff rate]
The degree of fluffing per 30 mm length of the end face was quantified with a microscope. The end face of the cut was photographed from the position where the liner paper and the microscope were perpendicular. A photograph is shown in FIG. The line connecting the valleys of the cut end face is taken as the base line, a straight line with a length of 30 mm is drawn parallel to the base line at a position away from the end face of 15 μm from the base line, and the length Y at which the straight line and the fluff intersect is measured. The fluff rate (%) per 30 mm length was determined.

[Measurement of sealing properties of paper containers]
(Pump condition output)
(1) Water was stored in the water tank, the graduated cylinder was turned upside down and placed in the water tank, and all the air in the graduated cylinder was removed and filled with water.
(2) Insert the needle for air injection of the pump (manufacturer: Sun Science, product name: SEAL TESTER FKT-100) into the graduated cylinder and inject air for 3 minutes so that the amount of air is about 5 mL. It was adjusted.

(Measuring method)
(1) An aluminum lid was heat sealed (sealing temperature: 160 ° C., sealing pressure: 5 kgf, sealing time: 2 s) on an empty paper container sample.
(2) Sealed paper container sample with silylated urethane resin adhesive (Konishi Co., Ltd., Ultra Versatile SU Premium Software), the joint part on the outer surface of the container other than the bottom joint part (joint part of body part, top curl) The bottom part of the top curl in contact with (see Fig. 9) was spotted (see Fig. 9), and the adhesive was left to dry for more than one day.
(3) Water was stored in the water tank (the height at which the 1 L beaker came out 1 cm), and the 1 L beaker was turned upside down and placed in the water tank, and all the air in the beaker was drained and filled with water.
(4) After the adhesive of the paper container sealed in (2) was cured, a seal-type septum was affixed on the aluminum lid member, and a needle for air injection of the pump was inserted from above. By using a septum, even after the needle has been stabbed, the hole is blocked by the elasticity of the septum rubber, and the inside of the container can be shielded from outside air and water.
(5) The paper container sample was placed in a beaker in the water tank so that air did not enter together.
(6) 25 mL of air was sent to the paper container sample in 15 minutes with a pump, and the air leaked from the bottom joint was stored in a beaker.
(7) After 15 minutes, a paper container sample was taken out, the remaining air was collected with a dropper, transferred to a graduated cylinder filled with water, and the amount of leaked air was measured.

[Evaluation method of end face penetration]
Sample: Processed paper with a resin layer laminated (base paper) or paper container penetrant: Yogurt (Manufacturer: Meiji, Product name: Bulgarian yogurt)
* 0.04g of a coloring agent (edible red No. 102) was added to 100g of each penetrant.

(Evaluation method)
(1) In the case of double-sided laminated paper, the double-sided laminated paper or paper container was cut into 25 × 50 mm as it was to obtain a test piece.
(2) In the case of single-sided laminated paper, an OPP adhesive tape (manufacturer: Nichiban, product name: carton tape 660N transparent -50) is applied to the non-laminated surface, and is sandwiched between rollers and crimped to prevent bubbles from entering. After preventing permeation from the non-laminated surface, a double-sided laminated paper or paper container was cut to 25 × 50 mm to obtain a test piece.
(3) The test piece was cut so as to be 25 mm in the paper making direction of the base paper and 50 mm in the direction perpendicular to the paper making direction of the base paper.
(4) The weight of the test piece was measured before being immersed in the permeation solution.
(5) The immersion liquid was put into the oven, and the oven temperature was set to 40 ° C. The temperature of the immersion liquid was 39.5 ° C.
(6) The test piece was immersed in the permeation solution for 24 hours.
(7) After 24 hours, the test piece was taken out, the liquid adhering to the base paper surface was wiped off, and the weight was measured.
(8) The end face penetration value was calculated by the following formula.
End face penetration (g / m) = (weight after immersion−weight before immersion) (g) / length of end face (0.15 m)

Furthermore, the following criteria evaluated the influence which it has on the container external appearance which is one of the commercial value of the paper container by the degree of edge surface penetration increasing.
○: Deterioration of the appearance of the container due to permeation of the end face of the contents does not occur or only slight deterioration.
X: Appearance of the container is clearly impaired by penetration of the contents into the end face.

[Evaluation method of mixing rate of bubbles in contents]
(material)
Tap water 10363g
137 g of potato starch (Hokuren Agricultural Cooperative Federation HRI, trade name: “Hokkaido potato starch”, ingredient: 100% potato starch)
Coagulant 72.5g (Ina Food Industry Co., Ltd., trade name: Inagel N-65P, ingredients: gelatin, agar, powdered candy)

(How to make contents for evaluation)
(1) Potato starch (137 g) and coagulant (Inagel N-65P, 72.5 g) were added to tap water (10363 g) to prepare a mixed solution.
(2) While stirring the prepared mixed solution well with a spoon (or spatula), the mixture was heated to 85 ° C. to completely dissolve the starch and the coagulant.
(3) The heated mixture was cooled with water and cooled to 40 ° C.
(4) After cooling, each paper container was filled with 80 g. The number of samples was 100 per standard.
(5) An aluminum lid material was sealed in the filled paper container (sealing temperature: 160 ° C., sealing pressure: 4 kgf, sealing time: 1 s).
(6) After sealing, the paper container was turned upside down for 1 minute, returned to its original position, and air-cooled at 23 ° C. for about 1 hour.
(7) After air cooling, 20 paper containers were packed in a corrugated cardboard box (length 40 cm × width 30 cm × height 8 cm) in one step, and cooled in a constant temperature and humidity machine at 4 ° C. for 8 hours.

(Evaluation method)
100 samples per level were opened, and it was visually confirmed whether or not bubbles were generated on the surface of the contents, particularly in the vicinity of the trunk joint. The bubble mixing rate was calculated as follows.
Bubble mixing rate = number of samples mixed with bubbles / total number of samples (100)

  Table 1 shows the evaluation results of the paper containers of Examples 1 to 11 and Comparative Examples 1 and 2.

  According to the comparison between the paper container of Examples 1-11 and the paper container of Comparative Examples 1-2, the paper of Comparative Example 1 in which the roughness (Ra) of the laminate surface on the container inner surface side is 0.3. In the paper container and the paper container of Comparative Example 2 where the roughness (Ra) is 3.1, bubbles are mixed into the contents, but the roughness (Ra) is 0.6 or 1.3. It can be seen that in the paper containers of Examples 1 to 11, no bubbles are mixed into the contents.

In the paper container of Comparative Example 1 having a surface roughness (Ra) of 0.3, fine wrinkles were generated on the inner surface side resin layer surface near the joint. This wrinkle is considered to be a factor causing the mixing of bubbles. When one edge of the body member blank and the other edge are overlapped and joined, at least the edge of the inner surface side resin layer is heated by applying hot air and then overlapped and pressure bonded. When the surface roughness Ra of the inner surface side resin layer is smaller than 0.4 μm by applying hot air to the edge of the layer and heating, fine wrinkles are generated on the inner surface side resin layer surface near the joint, Is easy to be devastated. It is considered that this makes it easier for bubbles to adhere and to separate.
The reason is unknown, but if the surface roughness Ra of the inner surface side resin layer is small, the surface of the smooth resin layer is melted uniformly by applying hot air and then pushed by the flow velocity of hot air It is thought that fine wrinkles were generated on the inner surface side resin layer surface in the vicinity of the joint portion because it flowed and cooled and fixed in a waved state.
On the other hand, if the surface roughness Ra of the inner surface-side resin layer is large, there are fine irregularities on the surface, so when hot air is applied to the surface of the resin layer, the convex portions are first melted and flow into the concave portions. It is thought that undulations due to the flow velocity of are less likely to occur. Actually, when a resin layer having a large surface roughness Ra was bonded, the inner surface side resin layer surface in the vicinity of the bonded portion was smoothed, and fine wrinkles were not observed.

The bubble generation rate is reflected in the time required for the bubbles to rise, and the time required for the bubbles to rise is significantly reduced in the paper containers of Examples 1 to 11 compared to the paper containers of Comparative Examples 1 and 2. It was.
Based on this, the paper containers of Examples 6 to 10 in which the food additive adheres to at least a part of the inner surface side of the trunk, and Examples 1 to 5 and Example 11 in which no food additive adheres The paper containers of Examples 6 to 10 in which the food additive adheres to at least a part of the inner surface side of the body portion are compared with the paper containers of Examples 1 to 5 and Example 11. Compared with the container, the time required for the bubbles to rise is shortened, and it can be seen that the effect of preventing the bubbles from remaining is excellent.

  Moreover, according to the comparison between Example 3 and Example 1, it can be seen that the effect of preventing bubbles from remaining in the contents can be further enhanced by reducing the fluffing rate of the end surface on the inner surface side of the container.

  In the paper container of Example 11 using the expander roller method, generation of wrinkles during bottom molding was confirmed near the circumference of the bottom. On the other hand, in the paper containers of Examples 1 to 10 and Comparative Examples 1 and 2 using the expansion sealing method, generation of wrinkles was not confirmed near the circumference.

  As a result of the evaluation of the container appearance, the container appearance was determined to be good in any of the paper containers of Examples 1-11.

  The configurations and combinations thereof in the embodiments described above are examples, and the addition, omission, replacement, and other modifications of the configurations can be made without departing from the spirit of the present invention. Further, the present invention is not limited by each embodiment, and is limited only by the scope of the claims.

DESCRIPTION OF SYMBOLS 1 ... Body part, 2 ... Bottom plate part, 3 ... Container main body, 4 ... Body part joint part, 4a, 4a '... End surface, 5 ... Processed paper, 6 ... Paper base material, 7 ... Inner surface side resin layer, 8 ... Outer surface Side resin layer, 9 ... bubbles, 10 ... paper container

Claims (14)

A paper container having a container body composed of a body part and a bottom plate part having a body joint part, and a resin layer provided on at least the inner surface side of the body part and the bottom plate part,
The paper container, wherein the resin layer provided on the inner surface side of the body portion has a surface roughness Ra of 0.4 μm or more and less than 1.5 μm.   The fluffed portion of the end surface of the body joint portion is defined as a portion where the line connecting the valleys of the end surface is a base line, a straight line parallel to the base line is drawn at a position 15 μm away from the base line, and the straight line and the fluff intersect 2. The paper container according to claim 1, wherein a fuzzing rate, which is a ratio of the fuzzy portion on the end face of the trunk joint portion, is 30% or less.   0.18 mL bubbles adhering adjacent to the end face of the body joint part on the inner surface side of the paper container in a state where the body joint part on the inner surface side of the paper container is vertically arranged in water The paper container according to claim 1 or 2, wherein the time required for the bubbles to rise by 30 mm along the resin layer is 40 seconds or less when the ascent rate is measured.   The paper container as described in any one of Claims 1-3 whose contact angle of the said resin layer of the said trunk | drum inner surface side and water is 60 to 98 degree | times.   In the method for measuring the sealing property of a joint portion of a container, which is measured by sealing the lid on the paper container and then submerging in water and sending air in an amount of 5 mL / min to the inside of the paper container. The volume of the air which leaks from a container is 3.0 mL or less, The paper container as described in any one of Claims 1-4.   The lubricant is attached to at least a part of the outer surface side of the body part or at least a part of the inner surface side of the body part, and the lubricant is a liquid paraffin or a silicone-based lubricant. A paper container according to claim 1.   The paper container as described in any one of Claims 1-6 in which a food additive adheres to at least one part of the inner surface side of the said trunk | drum.   The paper container according to claim 6 or 7, wherein the lubricant attached to at least a part of the inner surface side of the body portion contains the food additive.   The paper container according to any one of claims 7 and 8, wherein the food additive has an HLB of 1 or more and 17 or less.   8. The food additive is any one or more selected from the group consisting of glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, propylene glycol fatty acid ester, and lecithin. The paper container as described in any one of -9. Paper container according to any one of claims 7 to 10 food additive is attached by 0.005 / cm ² or more 17μg / cm ² or less on the inner surface of the barrel. Lubricant adheres to the lower outer peripheral surface which is within 2 cm from the lowermost part on the outer surface side of the body part, the lubricant contains a food additive, and the food additive is 0.005 μg / paper container according to any one of cm ² or more 17Myug / cm ² according to claim 1 to 11 attached below. In the paper container, a lubricant adheres to an upper inner peripheral surface that is within a range of 2 cm from the uppermost portion on the inner surface side of the body portion, the lubricant contains a food additive, and the upper inner peripheral surface paper container according to any one of claims 1 to 12, the food additive being adhered thereto at 0.005 / cm ² or more 17μg / cm ² or less.   The method for manufacturing a paper container according to any one of claims 1 to 13, wherein the body portion and the bottom plate portion are bonded together by an expansion sealing method.