JP2002294596A - Base paper for paper container and paper cup using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet of base paper for a paper container for foods having good printability or suitability for forming into a cup without lowering the strength of a paper cup with dew condensation water produced on a container wall when a cold beverage is placed in the paper container. SOLUTION: This sheet of base paper for the paper container has >=0.25 kgf nipping pressure strength measured by using a compression tester specified by JIS P 7733. The paper cup uses the sheet of base paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper container base paper.
The present invention relates to base paper suitable for paper containers such as containers for cold drinks such as beer and juice, as well as containers for cold food packaging such as yogurt and ice cream, and a paper cup using the same.

[0002]

2. Description of the Related Art Heretofore, as a base paper for a cold drink paper container, a paper base material having a water resistance imparted by impregnating and coating a paper base with wax has been used. However, since such base paper has low heat resistance, it cannot be used for paper containers in a field that is required to be used in common with hot beverages. Therefore, polyethylene laminated paper that can be used for both is widely used. In such polyethylene laminated paper, polyethylene is laminated on one side of the base paper, and the other side is usually decorated by printing.

[0003] A paper cup is formed by punching polyethylene laminated paper into a fan shape in which a cup is developed, and bonding both ends of a straight portion of the fan shape with the laminated surface inside to form a cup. Is inserted and crimped, and then subjected to a series of operations of performing a top curling process (a process of forming a portion serving as a mouth of a cup) in which a circumferential portion at an upper end is rolled out.

Accordingly, the inside of the paper cup is laminated with polyethylene, so that the water resistance is very high. However, the demand for cold drinks is high in summer when the outside temperature is high, and in the case of paper cups for cold drinks, the difference between the contents and the outside temperature causes dew condensation to occur outside the cup, and the paper base absorbs this water. This reduces the paper strength. As a result, the side of the paper cup held by the hand is softened, so that it becomes extremely difficult to hold the paper cup, and the function as the paper cup deteriorates.

In order to prevent such a decrease in strength due to condensation, water resistance is also required for the outer surface of the paper cup. Therefore, for example, when printing, a printing machine is used to impart a water resistance and a water repellency by printing a hydrophobic substance such as a varnish on the entire outer surface. However,
In this method, the printing color has to be reduced by one color, so the decorativeness of the outer surface of the paper container to differentiate it from other products is reduced and the operability is deteriorated, such as the need to adjust the drying conditions There were drawbacks. A method of laminating polyethylene on both sides of a paper substrate is also known, but this increases the manufacturing cost.

[0006] In order to solve such a problem, a method of providing a barrier layer containing polyvinyl alcohol, acrylic resin, or the like on a side other than the laminating side of the paper container base paper is also known. However, in this case, although water repellency is exhibited with a relatively low coating amount, it is necessary to apply a large amount of resin in order to impart water resistance in order to prevent a decrease in paper strength at the time of absorbing water, so that cost increases. Not only that, depending on the material used, there were drawbacks such as a decrease in printability and moldability due to a high coating amount.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present inventors have
As a result of intensive studies to solve the above-mentioned drawbacks, the present inventors have found that good results can be obtained by using a certain level of narrow pressure strength as the base paper, and have reached the present invention.
Accordingly, a first object of the present invention is to provide an inexpensive paper container base paper which has printability and molding suitability, and is hardly reduced in strength even when absorbing dew water. A second object of the present invention is to provide an inexpensive paper cup suitable for cold beverages.

[0008]

SUMMARY OF THE INVENTION The above objects of the present invention.
Is a compression strength measuring instrument specified in JIS B 7733
The narrow pressure strength measured by using
Paper container base paper, and a paper container using the same.
Achieved by In addition, it has such a pinching strength.
Paper container base paper is 0.05 g / m2 on at least one side of the paper base material.
²0.5g / m or more ²Less than the water repellent is applied
And 0.1 weight per pulp
Preferably, it is contained in an amount of at least 0.5% by weight.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a food paper container base paper according to the present invention will be specifically described. It is essential that the paper container base paper in the present invention has a pinching strength of 0.25 kgf or more, preferably 0.30 kgf or more. The method of measuring the narrow pressure strength in this case is as follows. A high-density polyethylene having a thickness of 20 μm is laminated on one side of the paper container base paper, and heat-sealed with the polyethylene laminated side facing inward to produce a cylinder having a diameter of 6 cm and a length of 15 cm. And add 250 ml of 4 ° C. water. Next, after leaving it for 15 minutes in an atmosphere of 23 ° C. and a relative humidity of 50%, the water was discarded and the stopper was removed. The side surface of the cylinder was immediately compressed 10 mm in a diameter direction by a compression tester specified in JIS B 7733. To measure the pinching strength.

[0010] In order to satisfy the pinching strength of the present invention, JI
The water repellency specified in SP 8137, the Cobb water absorption specified in JIS 8140, and the wet tensile strength specified in JIS P 8135 are important factors. If the water repellency is low, the water of the dew condensation water permeates the entire paper container, and the strength cannot be maintained unless the wet paper strength improver is added in an appropriate amount or more. Also, if the Cobb's water absorption is high, the penetration of moisture that cannot be prevented only by improving the water repellency causes a decrease in the pinching strength, so to prevent this, add a wet paper strength improver that is over the appropriate range. Is required. On the other hand, when the wet tensile strength is small, the water repellency and Cobb water absorbency need to be extremely increased, so that the water repellent is excessively applied, thereby adversely affecting printability and the like. .

As for the paper container base paper of the present invention, it is preferable to apply a water repellent to the paper substrate in order to prevent water absorption when dew condensation occurs as described above. As the water repellent, wax emulsions such as paraffin wax emulsions and polyethylene wax emulsions having good printability and suitability for forming into paper containers are preferable. However, depending on the material used, fluororesin, silicone, polyvinyl alcohol, acrylic resin, styrene / acrylic resin, styrene / butadiene resin, vinyl acetate resin, etc., which have relatively good printability and moldability, are also used. These may be used in combination with a wax-based emulsion. Further, it may be applied not only on one side but also on both sides as needed.

The appropriate amount of the water repellent applied is not limited by the properties of the water repellent and the base paper of the paper container of the present invention.
It is preferable to apply in a range of from 05 g / m ^{2 to} 0.5 g / m ² . If the coating amount is less than 0.05 g / m ² , sufficient water repellency cannot be obtained, and condensed water is easily absorbed, so that the paper strength may be reduced. Further, if the coating amount exceeds 0.5 g / m ² , the water repellency is not further improved, and the printing suitability and the molding suitability for a paper container are undesirably reduced. Examples of the method of applying the water repellent include a method using a known coating machine such as a size press coater, a gate roll coater, a blade coater, an air knife coater, and a curtain coater.

In the paper container base paper of the present invention, as described above, the pinching strength is 0.25 kgf in order to prevent the paper strength from being reduced when moisture in the paper is dewed due to a decrease in temperature or when dew is absorbed from the surface layer. That is essential. In order to impart such pinching strength, it is preferable to add a wet strength agent, and the addition method is to add a wet strength agent to the stock to make paper and fix it in paper. The addition method is preferred.

The wet paper strength improver used in the present invention can be appropriately selected and used from commonly used known ones. In particular, polyamide-polyamine resins, polyacrylamide resins, melamine Examples include a base resin. An appropriate amount of such a wet paper strength improver is 0.1 to 0.5 parts by weight based on 100 parts by weight of pulp. If the amount exceeds 0.5 parts by weight, it is difficult to obtain the effect corresponding to the amount added, which leads to an increase in cost and a decrease in disintegration, making it difficult to reuse as used paper. If the amount is less than 0.1 parts by weight, sufficient wet paper strength cannot be obtained.

The paper base material of the paper container base paper of the present invention is produced using wood pulp as a main raw material. As pulp, softwood kraft pulp, hardwood kraft pulp, groundwood pulp, thermomechanical pulp, chemithermomechanical pulp,
Deinked pulp or the like is used alone or mixed at an arbitrary mixing ratio. If necessary, fillers, sizing agents, paper strength improvers, yield improvers, dyes, and the like may be added. The basis weight of the paper substrate is not particularly limited,
For cold beverage paper instrument applications, 180 g / ^{m 2} or more 240 g / ^{m 2}
The following is preferred.

To manufacture the paper cup of the present invention, first, the wet paper strength improver is contained in an amount of 0.1 to 0.5% by weight based on pulp, and the narrow pressure strength is 0.25 kgf or more. the paper containers stencil paper making as the basis weight is ^{180g / m 2 ~240g / m 2} , 0.05g at least one surface thereof
/ M ^{2 to} 0.5 g / m ² of a water-repellent agent and a laminated paper in which polyethylene is laminated on the surface to be the inside of the cup as is known. Next, the obtained laminated paper is punched into a fan shape, which is a shape in which a cup is developed, and both ends of the linear portion of the fan are laminated with the lamination surface inside, thereby forming a cup shape. Insert the bottom paper prepared by punching it into a circular shape, insert it so that the laminated surface is on the inside, press it down, and then apply top curl processing (forming the part that becomes the mouth of the cup) by rolling the circumference of the upper end outward. It is easily manufactured by applying.

[0017]

The paper container base paper having the pinching strength of the present invention is
It is characterized by simultaneously satisfying the water repellency on the base paper surface and the water resistance by improving the wet paper strength of the base paper.Even if only one of them is satisfied, the desired performance as a target cold drink paper container base paper is obtained. I can't. For example, if only the water repellency of the paper container base paper is improved, when a cold drink is put into a cup and the outside temperature and humidity are high, it is possible to prevent water absorption due to condensation of moisture in the outside air, It is difficult to prevent a decrease in strength due to the cooling of the moisture in the paper voids and the attachment of water droplets in the paper layer. Further, even if only the wet strength is improved, the initial decrease in paper strength can be suppressed, but the effect on decorativeness and the decrease in strength over time cannot be avoided. The present invention has a synergistic effect with a small amount of chemical addition by having both of the above properties at the same time.

[0018]

EXAMPLES The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto. Parts and% in Examples and Comparative Examples
Represents parts by weight and% by weight, respectively, unless otherwise specified. In addition, for the paper container base paper manufactured in Examples and Comparative Examples,
The narrow pressure strength, water repellency, cup water absorption, wet tensile strength and moldability were evaluated as described below.

Nipping pressure strength: The obtained paper base material has a thickness of 20 μm.
m high-density polyethylene laminate is applied and heat-sealed to produce a 6 cm diameter cylinder. This one side is plugged and cold water of 4 ° C. is put in, and left for 15 minutes in an atmosphere of 23 ° C. and 50% relative humidity. Next, discard the water and remove the stopper.
B The side surface of the cylinder was compressed 10 mm in the diameter direction using a compression strength measuring device specified by B 7733, and the strength at that time was measured as the pinching strength.

Water repellency: JIS P
It was measured according to 8137.・ Cobb water absorption: JIS P
It was measured according to 8140. -Wet tensile strength: JIS P
It was measured according to 8135. -Moldability: The obtained base paper was laminated with polyethylene laminated paper, heated and bonded at 150 ° C with a heat sealer, and the moldability was evaluated by the time required for fusing (1 second or less:
○, 1-2 seconds: △, 2 seconds or more: ×).

Embodiment 1 Hardwood bleached kraft pulp (LB
KP) 90 parts and softwood bleached kraft pulp (NBKP) 10
Parts of a pulp suspension composed of 0.3 parts of a polyamide-polyamine resin (trade name: WS-57) as a wet strength agent.
0, manufactured by Nippon PMC Co., Ltd.) and several other papermaking chemicals such as sizing agents, and a sulfuric acid band as a fixing agent to prepare a slurry.
/ M ² was prepared.

Next, a wax emulsion (trade name: Size Pine W-116H, manufactured by Arakawa Chemical Industry Co., Ltd.) and a surface sizing agent (trade name: Polymaron 351) were added to the base paper.
s, Arakawa Chemical Industry Co., Ltd.) and polyvinyl alcohol (trade name: PVA-7100, Nippon Synthetic Chemical Industry Co., Ltd.)
Is adjusted to be 3: 2: 1 in terms of solid content weight ratio,
The obtained mixed solution was applied by a size press so as to have a dry weight of 0.5 g / m ² to prepare a paper container base paper. Table 1 shows the evaluation results of the obtained paper container base paper.

Embodiment 2 FIG. Same as Example 1 except that the amount of the wet strength agent used in Example 1 was changed to 0.1 part and the size press solution was subjected to size press so as to have a dry weight of 1.0 g / m ^2. To produce a paper container base paper. Table 1 shows the evaluation results of the obtained paper container base paper.

Embodiment 3 FIG. A paper container base paper was produced in the same manner as in Example 1 except that the amount of the wet strength agent used in Example 1 was changed to 0.5 part, and no wax was added to the size press solution. Comparative Example 1 A paper container base paper was prepared in the same manner as in Example 1, except that the wet paper strength enhancer was not added as a papermaking chemical. Table 1 shows the evaluation results of the obtained paper container base paper. Comparative Example 2. A paper container base paper was produced in the same manner as in Example 1 except that the amount of the wet strength agent was set to 0.05 part. Table 1 shows the evaluation results of the obtained paper container base paper. Comparative Example 3 An OP varnish of 10 g / m ^{2 was} applied to high-quality paper having a basis weight of 200 g / m ² using a gravure printing machine to prepare a paper container base paper. Table 1 shows the evaluation results of the obtained paper container base paper.

[0025]

[Table 1]

From the results in Table 1, it can be seen that the food paper container base paper of the present invention has water repellency on its surface, so that it can prevent water absorption at the time of dew condensation. As a result, the paper strength can be suppressed, and the printability and moldability are good, and it has been proved that the paperboard base paper has extremely excellent properties.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B65D 65/42 B65D 65/42 C D21H 21/16 D21H 21/16 21/20 21/20 F term (reference) 3E075 BA33 BA35 BA38 BB22 CA01 DD12 DD42 DD43 GA04 3E086 AB01 AD06 BA04 BA14 BA15 BA24 BB62 BB71 CA11 DA01 DA08 4L055 AA02 AA03 AC06 AG51 AG64 AG84 AH13 AH17 AH23 BE08 BE13 EA07 EA08 EA14 EA32 FA13 FA15 FA23 GA05

Claims (4)

[Claims] 1. A paper container base paper characterized in that a pinching strength measured by using a compression tester specified in JIS B 7733 is 0.25 kgf or more. 2. A water-repellent agent is provided on at least one surface of the paper base material.
0.05 g / m coated with are less than ² or more 0.5 g / m ^2, paper containers according to claim 1 containing less than 0.1 wt% to 0.5 wt% per pulp and wet strength enhancing agent in the paper substrate Base paper. 3. A paper cup manufactured using the paperboard base paper according to claim 2, wherein the basis weight is 180 g / m ² or more and less than 240 g / m ² , wherein a water repellent is applied to an outer surface of the cup. A paper cup characterized in that polyethylene is laminated on the inner surface of the cup. 4. The paperboard base paper according to claim 2, wherein the basis weight is 180 g / m ² or more and 240 g / m ² or less. A cylinder was prepared by heat sealing with the polyethylene laminate side of the base material obtained by punching out the laminated paper into a fan shape inside, and then a circular polyethylene laminated paper container base paper separately prepared for the bottom surface, the polyethylene laminated surface A method for producing a paper cup, comprising: performing top curling on an upper portion after insertion and pressure bonding so that the inside of the paper cup is inward.