JPH0319992A - Water-repellent coating agent for paper container - Google Patents

Abstract

PURPOSE:To provide the subject coating agent having excellent water resistance, water repellency and heat sealability and suitable for imparting the water repellency to the outer surface of a paper container having the inner surface covered with PE by adding an ethylenic copolymer and a mold release agent to a wax water-repellent in specific ratios. CONSTITUTION:The objective coating agent contains as solid contents (B) 30-100 pts.wt., preferably 50-70 pts.wt., of an ethylenic copolymer (preferably a copolymer of ethylene/ethyl acrylate/maleic anhydride in a molar ratio of 95-68/4-30/1-5) and (C) 1-30 pts.wt. of a mold release agent (preferably a silicon compound) based on (A) 100 pts.wt. of a wax water-repellent (preferably an ozokerite water-repellent).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a water-based coating agent for paper containers, particularly for imparting water repellency to the outer surface of a paper container whose inner surface is coated with polyethylene. The present invention relates to a coating agent suitable for.

[Conventional technology] Paper food containers used in vending machines, so-called fast food restaurants, convenience stores, etc. can be roughly divided into cold types, which are used for cold drinks such as cola and juice, and cold types, which are used for hot coffee and hot cocoa. There is also the Bot I type, which is used for hot drinks such as black tea.

Most cold-type paper containers have wax coated on their inner and outer surfaces to make them water repellent. For example, a typical waxed cup is manufactured by first punching paper, then gluing it into the shape of the cup, and then applying wax to the inside and outside surfaces of the cup. The reason for this process of molding and applying wax is that if the paper is coated with wax from the beginning, gluing or heat sealing afterwards would be difficult. Furthermore, when hot beverages such as hot drinks and coffee are poured into paper containers coated with wax, the wax begins to melt, making the scale undesirable from a sanitary standpoint, and significantly deteriorating the strength of the container.

On the other hand, most hot-type paper containers are made from paper coated with water-resistant polyethylene film on one side, then punched out and then shaped using glue or heat sealing with this side facing inside. be. However, although the inner surface of such hot type paper containers has sufficient water repellency, when cold drinks such as cola and juice are used, especially in recent years ice is often used, condensation can form on the outer surface of the container. Since it lacks water repellency, the paper has the disadvantage that water is absorbed by the paper and the strength of the paper container deteriorates.

[Problems to be solved by the invention] As mentioned above, conventional paper containers were divided into cold types and hot types, making them difficult to use in so-called fast food restaurants and convenience stores, and in vending machines, etc. So what if you need to store both separately in a limited space? Therefore, there is a strong desire to provide a dual-use paper container that can be used for both cold and hot beverages.

As a dual-use type paper container, one manufactured using paper coated with polyethylene film on both sides is known, but there is a problem in that it is very expensive and its uses are limited in terms of cost. In addition, there are other problems such as static electricity is likely to be generated, dust adheres to the surface of the container, which is undesirable from a sanitary standpoint, and the containers become difficult to separate from each other. Furthermore, the heat seals the heat-sealed area, which clouds the area and deteriorates its appearance, making it difficult to heat the area sufficiently.

Another possibility is to cover the inner surface of the container with a polyethylene film and apply a water repellent such as wax to the outer surface. However, heat sealing is difficult with water repellent agents such as wax, and in order to maintain heat sealability, it is necessary to apply so-called pattern coating or partial coating in which no water agent is applied to the heat seal area called the side seam. Become. the result,
If the old liquid agent is transparent, F (1. It is difficult to detect the presence or absence of the liquid agent coating, and the registration during punching is difficult
This makes the equipment expensive, and at the same time, the manufacturing process is complicated, reducing productivity.

The present invention has been developed in consideration of such circumstances, and when manufacturing water-repellent paper containers that can be used for both cold and hot food and drink containers, the heat-sealability is not inhibited even if the coating is applied to the entire surface of the base paper in advance. The purpose of the present invention is to provide an aqueous Fa coating agent.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention uses an organic solvent suitable for coating one side of a base paper coated with a polyethylene film on the other side with ethylene copolymer. It provides a liquid coating agent containing a polymer, a wax-based F(a water agent, and a mold release agent).

The ethylene copolymer used in the MA composition of the present invention is mainly used to impart heat-sealability to the paper with polyethylene film, and includes ethylene/acrylic acid copolymer, ethylene/acrylic acid ester copolymer, ethylene/
Even if it is a binary copolymer such as a vinyl acetate copolymer, or a ternary copolymer such as an ethylene/acrylic acid/maleic acid copolymer or an ethylene/acrylic acid ester/maleic acid copolymer, Alternatively, chlorinated products of these binary copolymers and tertiary copolymers may be used.

The ethylene copolymer must be soluble in an organic solvent, and in this respect, a molar ratio of comonomer to ethylene of about 10-30 is preferable, and chlorinated ethylene copolymers have a relatively high solubility. is also preferable. In terms of solubility and odor, terpolymers are more preferred.

The ethylene copolymer used in the coating agent of the present invention can be one or more of the above, and two or more of the same type but with different specifications may be used to improve heat sealability. , it is also possible to improve solubility. Note that copolymers other than ethylene copolymer such as vinyl chloride vinyl acetate copolymer are not suitable for use in the coating agent of the present invention since they are heat-sealed with polyethylene.

Such an ethylene copolymer is used as the wax-based water repellent 100 described below.
If it is less than 30 parts by weight, heat-sealing properties with the polyethylene film cannot be obtained, and if it exceeds 100 parts by weight, blocking to the mold tends to occur during heat sealing, and it becomes difficult to dissolve in a solvent. It's coming. Therefore, the wax-based water repellent 100 made of ethylene copolymer
The proportion by weight is preferably 30 to 100 parts by weight, more preferably 50 to 70 parts by weight.

Wax-based water-drying agents used to impart water repellency to paper include paraffin wax, a mixture of paraffin wax and ethylene/vinyl acetate copolymer, and acid value 70-70.
140 maleated paraffin wax, microcrystalline wax, ozokerite wax, ceresin wax, Fischatrobus polyethylene wax, and polyethylene wax with a degree of polymerization of 3000 or less. In particular, in terms of solubility in organic solvents, fractional properties, and odor, ozokerite wax is preferred, and ceresin wax is more preferred.

In addition, vegetable waxes such as rice wax and carnauba wax, and animal waxes such as beeswax and lanolin,
It is unsuitable as a water repellent for the coating agent of the present invention because it has poor affinity with the ethylene copolymer for imparting heat-sealing properties and inhibits heat-sealing properties. The wax-based water drying agent preferably accounts for 1 to 50% by weight, and 3 to 30% by weight of the entire liquid string composition.
% by weight is more preferred. In particular, if the wax-based water repellent exceeds 50% by weight, the ratio of the ethylene copolymer decreases from the viewpoint of solubility, which deteriorates the heat sealability with the polyethylene film, which is undesirable.

The melting point of the wax-based water repellent is preferably 60 to 120°C, more preferably 80 to 100°C. When the melting point exceeds 120°C, the solubility in solvents decreases, making it impossible to achieve high agricultural yields, and when the melting point falls below 60°C, hot beverages cannot be placed in paper containers. The problem arises that it melts at times. For example, the temperature of hot coffee in a vending machine is about 92 degrees Celsius, so
A wax-based water repellent having a melting point of 80°C to 100°C is suitable.

It goes without saying that two or more of the above wax-based water repellents may be used in the present invention. For example, it is also possible to use a combination of Ceresinwa nkusu and Balafinwa nkusu. Generally called ceresin waxζ
This is 10 to 30% by weight, and in some cases 50 to 80% by weight of paraffin wax. There are also H-combined products, and there are also cases where it is not necessary to mix baraffin wanx.

As mold release agents, silicon compounds, phosphate esters, pendant resins, fluorine activators, secondary amine activators,
Usual waxes such as fatty acid amide waxes can be used, and silicone compounds are particularly preferred from the viewpoint of safety as a food container. The mold release agent is necessary to prevent blocking or picking during heat sealing, and the amount thereof is preferably 1 to 30 parts by weight per 100 parts by weight of the wax-based water solution. If the amount of the mold release agent exceeds 30 parts by weight, the heat-sealability will deteriorate, so care must be taken.

Examples of organic solvents for dissolving or dispersing each of the above components to obtain a liquid conversion product include toluene, xylene,
Hexane etc. can be used. Moreover, in addition to the above-mentioned components, ordinary antifoaming agents and the like can be added as necessary. It is better to keep the proportion of the organic solvent as low as possible; however, if the proportion is small, the viscosity increases, so the proportion should be selected appropriately in relation to the coating method. Since there are restrictions in terms of solubility, the proportion of solvent is usually 60 to 80% by weight of the total.
}There are no particular restrictions on the method of applying and drying the nocturnal string composition. However, when printing on paper using a gravure printing machine or the like, it is convenient for container manufacturing to apply and dry the liquid silk composition using the same gravure printing machine immediately after printing. It may be applied only once, but pinholes can be minimized by applying it multiple times.

[Function] One side of base paper for paper containers is coated with a laminated polyethylene film, and the other side is coated with the coating agent of the present invention containing an ethylene copolymer, a wax-based water repellent, a mold release agent, etc. Since it has a dry film, both sides have sufficient water resistance and water repellency as a food and drink container, and good heat sealability can be ensured between both sides.

Therefore, when a container manufactured by heat sealing using water-repellent paper whose outer surface is coated with the coating agent of the present invention is used as a cold type, even if dew condenses on the outer surface, water penetration into the paper can be suppressed. Furthermore, even when used as a hot type, wax etc. will not melt out, so it can be used as a dual-purpose paper container. Note that the surface coated with polyethylene film is usually the inside of the container, that is, the side into which the food/beverage product is placed.

In addition, since the water-repellent coating agent of the present invention has excellent heat-sealability, it is possible to apply the coating agent of the present invention containing a water-repellent agent to the entire surface of the area to be heat-sealed. At times, losses due to pattern matching are eliminated. Furthermore, in addition to its excellent heat-sealing properties, it also has excellent mold release properties, making it difficult to block or bump the mold during heat-sealing, and also has good sliding properties between containers in a penting machine. .

It should be noted that if printing is performed on the base paper for paper containers before applying the coating agent of the present invention as described above, the dried film will serve as an overcoat for printing, which is convenient in terms of the process.

[Example 1] One side of white paperboard was coated with a polyethylene film with a thickness of 20 Jim by lamination, and then the following coating agent of Asasei was coated on the other side at a rate of 10 g/TT1' using a roll coater. It was applied in the following proportions and thoroughly dried with hot air.

Coating agent: (1) Ethylene/vinyl acetate copolymer (comonomer content 25% by weight) NUC3195 (manufactured by Nippon Unica Co., Ltd.). ．． ．． ．． ．． ．． ．．
1 0wt% (2) Oxidized paraffin wax OX-WEISSEN 15 (manufactured by Nippon Seirosha) 5wt
% (3) Silicone mold release agent TSM620 (manufactured by Toshiba Silicone Corporation). ．． ．． ．． ．． ．． 1
wt% (4) Silicone antifoaming agent KF96 (manufactured by Shin-Etsu Chemical Co., Ltd.). ．． ．． ．． ．． ．． 0.1w
t%(5)}-Luene. ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．．
The water-repellent paper obtained at 83.9 wt% was punched out into the side and bottom parts of the cup, and the fan-shaped ends of the side parts were stacked one side against the other so that the laminated side of the polyethylene film was on the inside. , this part is 180
Heat sealed at °C. Thereafter, the bottom part was glued and molded, and the upper edge was molded to form a cup. This paper cup has sufficient strength, water resistance, and water-shedding properties, and can be used not only as a hot cup but also as a cold cup with no deterioration in strength due to condensation on the outer surface even when a cold drink is poured into the cup.

Example P7 Ri2 Water-repellent paper was produced in the same manner as in Example 1 above, except that the following coating agent silk composition was used.

Coating agent composition: (1) Ethylene/acrylic acid ester/maleic acid copolymer (comonomer content 25% by weight) NUC6570 (
Manufactured by Nippon Unica). ．． ．． ．． ．． 10wt% (2) Paraffin wax SP-0110 (manufactured by Nihon Seisei Co., Ltd.). ．． ．． ．． ．． ．． ．． ．． ．．
．． ．． 5wt% (3) Silicone mold release agent L-45 (manufactured by Nippon Unica Co., Ltd.). ．． ．． ．． ．． ．． 1wt%
(4) Silicone antifoaming agent KF-96 (manufactured by Shin-Etsu Chemical Co., Ltd.). ．． ．． ．． ．． O. lw
t% (5) Toluene. ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． 83
．． A paper cup manufactured in the same manner as in Example 1, Row 1 using the 9 wt % dehydrated paper has sufficient strength, water resistance, and water repellency, and can be used as both a hot type and a cold type. It was something.

Nawamizu paper was produced in the same manner as in Example 1 above, except that the following coating agent composition was used.

Coating agent composition: (1) Ethylene/ethyl acrylate/maleic anhydride copolymer (comonomer content 15% by weight) Bondine IX
8030 (manufactured by Sumika CDF Chemical Co., Ltd.). ．． 、． ．．
．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． 3 parts by weight (2) Ethylene/ethyl acrylate/maleic anhydride copolymer (comonomer content 31% by weight) Bondine HX
8060 (manufactured by Sumika CDF Chemical Co., Ltd.). ,,,,
．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． 3 parts by weight (3) Ceresin wax 11.683 (manufactured by JONK, Netherlands) 10 parts by weight (4) Silicone mold release agent ST 105PA (manufactured by Toshi Silicone) 1 part by weight (5) L-luene. ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． 、．
8 A paper cup manufactured in the same manner as in Example 1 using the obtained 3 parts by weight free water paper has sufficient strength, water resistance, and water repellency, and can be used as both a hot type and a cold type. It was something.

Comparative Example 1 A paper towel was produced in the same manner as in Example 1, except that the following coating composition was used.

Coating agent composition (1) Vinyl chloride vinyl acetate copolymer Luron QA431 (manufactured by Tosoh Corporation) 20 parts by weight (2) Mold release agent Tosvar 120 (manufactured by Toshiba Silicone Corporation) 1 part by weight (3) Toluene. ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．．
．． 7. Approximately 3 cm x 5 pieces of the obtained 9 parts by weight paper
The heat-sealing property was tested by cutting the paper into pieces of am paper and stacking the two pieces of paper so that the surface coated with the polyethylene film and the surface coated with the coating agent were in contact with each other. Judgment was made based on the peel strength of the paper piece using a heat seal tester manufactured by Nippon T.M.C. Heat sealing conditions are 14
The test was conducted at 0° C. x 1.5 kg/square mark x 1.7 seconds, and the acceptance criteria were those in which delamination, that is, picking occurred when the heat-sealed portion was pulled and peeled off by hand. However, the heat sealability of this comparative example was unacceptable.

Comparative example 2 The following coating agent paste was produced.

Coating agent composition; (1) Ethylene/ethyl acrylate/maleic anhydride copolymer Bondine HX8030 (manufactured by Sumika CF Co., Ltd.) 5
Parts by weight (2) Carnauba wax. ．． ．． ．． ．． ．． ．． ．． ．． ．． 1
0 parts by weight (3) Mold release agent GAFAC-RS710 (manufactured by Toho Chemical Co., Ltd.)
．． i parts by weight (4) toluene. ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．． ．．
．． ．． ．． ．． ．． ．． ．． 84 parts by weight However, the subject composition had poor affinity between the wax and the ethylene copolymer and separated into two layers, making it impossible to coat.

[Effects of the Invention] According to the present invention, a paper container that has sufficient water resistance and Fa water resistance on both sides and has good heat sealability between both sides can be manufactured using almost the same equipment as before. We can provide water-repellent paper at low cost.

Therefore, paper containers manufactured using this water-repellent paper in almost the same way as before were clearly divided into cold types and hot types; It is extremely useful as it can be used as a dual-purpose type that can be shared with other people, and can eliminate mixed use at automatic vending machines, Firth 1, food stores, etc.

Claims (5)

[Claims] (1) For a paper container characterized by having 30 to 100 parts by weight of an ethylene copolymer and 1 to 30 parts by weight of a mold release agent per 100 parts by weight of a wax-based water repellent as a solid content. Water-repellent coating agent. (2) The water-repellent coating agent for paper containers according to claim 1, wherein the wax-based water repellent is an ozokerite-based wax. (3) The wax-based water repellent has a melting point of 60 to 120°C.
The water-repellent coating agent for paper containers according to any one of claims (1) and (2). (4) The above-mentioned claim (1) wherein the ethylene copolymer is an ethylene/ethyl acrylate/maleic anhydride copolymer.
The water-repellent coating agent for paper containers according to any one of 1) to (3). (5) Claims (1) to (1) above, wherein the molar ratio of each component of the ethylene/ethyl acrylate/maleic anhydride copolymer is ethylene 95 to 68, ethyl acrylate 4 to 30, and maleic anhydride 1 to 5. The water-repellent coating agent for paper containers according to any one of (4).