KR102152264B1 - Recyclable dampproof kraft paper and preparation of sugar sack by using it - Google Patents

Abstract

The present invention relates to recyclable damp-proof kraft paper and a sugar sack preparation method using the same. More specifically, one surface or both surfaces of kraft raw paper is coated with a damp-proof layer formed of a coating agent composition having a glass transition temperature (Tg) of -40 to -30°C and containing: 40 to 50 wt% of styrene acrylic emulsion; 35 to 45 wt% of water; 5 to 10 wt% of physical property supplement; 3 to 10 wt% of humectant; 1 to 3 wt% of a leveling agent; and 0.5 to 1 wt% of an antifoaming agent.

Description

Recyclable dampproof kraft paper and preparation of sugar sack by using it}

The present invention relates to an easily recyclable kraft moisture-proof paper and a method of manufacturing a sugar bag using the same, and to describe in more detail, on one or both sides of the kraft base paper, 40 to 50% by weight of styrene acrylic emulsion; 35 to 45% by weight of water; 5 to 10% by weight of a physical property supplement; 3 to 10% by weight of a wetting agent; 1 to 3% by weight of a leveling agent; It relates to a kraft moisture-proof paper coated with a moisture-proof layer made of a coating composition comprising 0.5 to 1% by weight of an antifoaming agent and a glass transition temperature (Tg) of -40°C to -30°C, and a method of manufacturing a sugar bag using the same.

Kraft paper is a yellowish brown paper made mainly of unbleached kraft pulp, a kind of chemical pulp, and has the advantage of being tough and strong, not slippery, and eco-friendly, so it has long been used for cement, fertilizer, feed, grain, etc. It is widely used as a packaging area for sugar and milling. However, since such kraft paper is vulnerable to moisture due to its material characteristics, in order to use it as a zone for food materials such as sugar or milling, it must be subjected to moisture-proof treatment to block moisture.

Conventionally, the most common method of moisture-proofing kraft paper is a method of manufacturing a moisture-proof paper by laminating a polyolefin-based film such as polyethylene (PE), polypropylene (PP), and polyvinylidene chloride (PVDC) on the kraft base paper. However, although the laminated kraft moisture-proof paper produced in this way can obtain sufficient moisture-proof effect, it is difficult to separate and recycle the polymer material and pulp material because it is not easily dissociated by water. Therefore, waste is incinerated. There was a problem of causing various environmental pollution in the process of landfill or landfill treatment.

In order to solve this problem, efforts have been made to improve the dissociation property of kraft moisture-proof paper by using acrylic emulsion. For example, Patent No. 10-168974 (October 08, 1998) describes 90 to 50 parts by weight of an acrylic emulsion with a glass transition temperature (Tg) in the range of 25 to 70°C, and a rosin with a softening point in the range of 90 to 110°C. Moisture-proof paper coated with a coating liquid composition containing 10 to 50 parts by weight of a modified wax-based emulsion and 5 to 20 parts by weight of an inorganic powder to prevent slipping and blocking is introduced.

The moisture-proof paper has the effect of improving dissociation for recycling, but when it is used as a sugar zone, there is a risk that the inorganic powder may be incorporated into the sugar component, and the surface of the zone is too slippery due to the wax-based emulsion, so handling is difficult. It is not suitable for use as a food zone because it is not easy to use.

In addition, in Patent No. 10-537733 (December 13, 2005), an undercoat layer and a top coat layer are sequentially applied to the upper surface of the kraft paper, but the undercoat layer is a mixture of inorganic pigments and acrylic emulsion with a coating amount of 5 to 15 g/m². Renewable kraft moisture-proof paper, which is coated with a mixture of acrylic emulsion and wax emulsion, is applied in a coating amount of 5 to 15 g/m2 is introduced as the top coating layer.

However, this kraft moisture-proof paper is complicated because the top coating layer has to be applied again after the under coating layer is applied, and when it is used as a sugar zone, the wax component contained in the top coating layer melts at high temperatures and contaminates sugar particles. It is not preferable because there is a risk of discoloration.

In addition, Patent No. 10-1329259 (2013.11.07.) states that a coating composition obtained by gelling starch on unbleached kraft paper, a coating composition obtained by mixing a paraffin wax emulsion in an alcohol solution, or a polyethylene emulsion mixed with an alcohol solution. There is proposed an unbleached kraft packaging paper in which a first coating layer is formed using a coating composition selected from among coating compositions, and a second coating layer is formed on the first coating layer with a coating composition in which a cellulose derivative is mixed with an acetate-based solvent. .

However, since the unbleached kraft packaging paper has to be coated with a second coating layer on the first coating layer again, the overall manufacturing process is complicated, there is a high risk of product defects and manufacturing costs are high.

Patent No. 10-168974 (1998.10.08.) Patent No. 10-537733 (2005.12.13.) Patent No. 10-1329259 (2013.11.07.)

Accordingly, an object of the present invention is to provide a kraft moisture-proof paper suitable for packaging and storage of sugar because it is excellent in dissociation properties and is easy to recycle, and does not change the color or particle state of sugar even if sugar is stored for a long time in severe climatic conditions. will be.

Another object of the present invention is to provide a method of manufacturing a sugar bag that is easy to recycle with a simple manufacturing process and low manufacturing cost using the kraft moisture-proof paper.

Easy to recycle kraft moisture-proof paper according to the present invention, on one or both sides of the kraft base paper, and 40 to 50% by weight of styrene acrylic emulsion; 35 to 45% by weight of water; 5 to 10% by weight of a physical property supplement; 3 to 10% by weight of a wetting agent; 1 to 3% by weight of a leveling agent; It is characterized in that a moisture-proof layer made of a coating composition containing 0.5 to 1% by weight of an antifoaming agent and having a glass transition temperature (Tg) of -40°C to -30°C is coated.

The manufacturing method of the sugar band using the kraft moisture-proof paper according to the present invention comprises the steps of: A) preparing a kraft base paper having a basis weight of 50 to 140 g/m ² ; B) 40 to 50% by weight of styrene acrylic emulsion, 35 to 45% by weight of water, 5 to 10% by weight of a physical property supplement, 3 to 10% by weight of a wetting agent, 1 to 3% by weight of a leveling agent, and 0.5 to a defoaming agent Preparing a coating composition consisting of 1% by weight, a glass transition temperature (Tg) of -40 ℃ ~ -30 ℃; C) coating the coating composition on one side of the kraft paper at an application amount of 5 to 20 g/m ² , and drying it to prepare a kraft moisture-proof paper; D) cutting the kraft moisture-proof paper according to a preset standard and joining the necessary parts to produce a seoldang zone; It characterized in that it comprises a.

The kraft moisture-proof paper according to the present invention and the sugar band manufactured using the same have the effect of not changing the color or particle state of sugar even if the sugar is stored for a long time under severe climatic conditions, and furthermore, it is excellent in dissociation by water and is recycled. This has an easy effect.

Hereinafter, the technical configuration of the present invention will be described in detail using a preferred embodiment of the present invention. However, even if the configuration is essential for carrying out the present invention, detailed descriptions of matters that are introduced in the prior art or that can be easily implemented by a person of ordinary skill in the art will be omitted.

The easy-to-recyclable kraft moisture-proof paper according to the present invention has a structure in which a moisture-proof layer made of the coating composition according to the present invention is coated on one or both sides of the kraft base paper that becomes a base sheet.

The coating composition constituting the moisture-proof layer includes 40 to 50% by weight of styrene acrylic emulsion, 35 to 45% by weight of water, 5 to 10% by weight of a physical property supplement, 3 to 10% by weight of alcohol, and 1 to 3% by weight of a leveling agent. % And 0.5 to 1% by weight of an antifoaming agent.

The styrene acrylic emulsion is a base resin constituting the moisture-proof layer, and a glass transition temperature (Tg) of 10 to 20% by weight of a styrene resin having a 100°C, preferably 15% by weight, and a glass transition temperature (Tg) of -50°C Phosphorus 2-ethylhexyl acrylate 80 to 90% by weight, preferably 85% by weight.

Here, when the content of the styrene resin exceeds 20% by weight or the content of 2-ethylhexyl acrylate is less than 80% by weight, the glass transition temperature (Tg) of the coating composition is increased, and the properties of the moisture-proof layer are cured and moisture-proof. There is a problem that the function is deteriorated. Conversely, when the content of the styrene resin is less than 10% by weight or the content of 2-ethylhexyl acrylate exceeds 90% by weight, the moisture-proof function of the moisture-proof layer increases, but the so-called blocking that the same components are aggregated during the coating process. ) As the phenomenon occurs, it is difficult to form a uniform moisture-proof layer.

Next, water, as a solvent for the styrene acrylic emulsion, functions to improve fluidity and dispersibility. If the content of the water is less than 35% by weight, the viscosity of the coating composition is too high, so that uniform coating is difficult, and if it exceeds 45% by weight, there is a problem that drying of the applied moisture-proof layer is delayed.

The physical property supplement has a function of improving the water resistance of the moisture-proof layer, and it is preferable to use silicone. If the content of the physical property supplement is less than 5% by weight, there is a problem that the water resistance of the moisture-proof layer is insufficient. On the contrary, if it exceeds 10% by weight, the slip property of the moisture-proof layer is excessively improved, resulting in product defects in the process of manufacturing a sugar band. There is a problem that the likelihood of this occurrence increases.

The wetting agent has a function of easily penetrating into the kraft base paper by reducing the surface tension of the coating composition, and it is preferable to use ethanol. If the content of the wetting agent is less than 3% by weight, there is a problem that the coating composition does not easily penetrate into the kraft paper, and if it exceeds 10% by weight, the coating composition is dried too quickly, so an anilox roller during coating operation There is a concern that a so-called panmeim phenomenon may occur in the (anilox roller).

The leveling agent has a function of maintaining good transferability to the kraft base paper and the surface state of the moisture-proof layer when coating the coating composition, and is preferably a polyether siloxane copolymer. If the content of the leveling agent is less than 1% by weight, there is a problem that the transferability of the coating composition is poor, and if it exceeds 3% by weight, bubbles are generated a lot when applying the moisture-proof layer, resulting in poor surface condition of the moisture-proof layer. there is a problem.

Finally, the antifoaming agent functions to remove air bubbles generated when the coating composition of the present invention is coated on the kraft base paper, and is preferably a polyether siloxane copolymer and a hydrophobic silica. If the content of the antifoaming agent is less than 0.5% by weight, bubbles are generated when the moisture-proof layer is applied and the surface condition of the moisture-proof layer is poor. On the contrary, if it exceeds 1% by weight, pores such as craters are generated in the moisture-proof layer, thereby preventing moisture. There is a problem that is not effective.

Meanwhile, the coating composition preferably has a glass transition temperature (Tg) of -40°C to -30°C. If the glass transition temperature (Tg) of the coating composition is less than -40°C, the formation of a coating film is insufficient when applying the coating composition, and as a result, the water resistance of the moisture-proof layer is weakened. There is a problem that a blocking shape occurs because the physical properties become soft.

In addition, the coating amount of the coating composition is preferably 5 ~ 20g / m ² . If the coating amount is less than 5g/m ^{2, the} desired moisture-proof effect cannot be obtained, and if it exceeds 20 g/m ² , the increase in the accompanying effect is insignificant compared to the increase in manufacturing cost, resulting in poor cost performance.

Hereinafter, a method of manufacturing a sugar band according to the present invention will be described by dividing it into steps A) to D).

First, in step A), kraft paper is prepared. It is preferable to use the kraft base paper having a basis weight of 50 to 140 g/m ² . Here, the basis weight means the weight of paper corresponding to a certain area, for example, means the weight of paper corresponding to an area of 1 m ² .

If the basis weight of the kraft paper is less than 50g/m ² , the tear strength (mN) and tensile strength (N/15mm) are too weak, so if used as a sugar bag, the bag may be damaged during transportation or handling, and vice versa. If it exceeds g/m ² , the thickness becomes too thick, making handling inconvenient during the manufacturing process as well as increasing manufacturing cost, which is not preferable.

In the next step B), 40 to 50% by weight of a styrene acrylic emulsion, 35 to 45% by weight of water, 5 to 10% by weight of a property supplement, 3 to 10% by weight of a wetting agent, 1 to 3% by weight of a leveling agent, and To prepare a coating composition consisting of 0.5 to 1% by weight of the antifoaming agent and having a glass transition temperature (Tg) of -40°C to -30°C. A detailed description of the components and contents of the coating composition is as described above.

In the next step C), the coating composition is coated on one side of the kraft paper at an application amount of 5 to 20 g/m ² and dried to prepare a kraft moisture-proof paper with a moisture-proof layer on one side. If the moisture-proof layer is coated on both sides of the kraft paper in step C), the moisture-proof effect will naturally increase, but even if the moisture-proof layer is coated on only one side, the moisture-proof effect required for the sugar band can be sufficiently secured.

Therefore, if the moisture-proof layer is coated on both sides of the kraft paper, the so-called cost-effectiveness is deteriorated due to the so-called increase in manufacturing cost, and it takes more cost and more time to dissociate the waste paper. There is a disadvantage that the manufacturing and transporting operation becomes inconvenient.

So, in the present invention, by making the surface coated with the moisture-proof layer as the inner surface of the sugar bag and the surface not coated with the moisture-proof layer as the outer surface of the sugar bag, sufficient moisture resistance, excellent dissociation property, and easy workability can be secured. I can.

Meanwhile, the coating operation of step C) may be performed using a FLEXO printing machine. Among them, it is preferable to carry out a roller coating method using a rubber roller of a CI FLEXO printing machine. The CI (Central Impression) printing machine is a rotary press of a central pressure type, and is usually used for high-precision printing. It is preferable to operate the CI printer at an operating speed of 33 to 100 m/min, a coating temperature of 19 to 110° C., and a working tension of 35 kg of unwind, 45 kg of outfeed, and 35 kg of rewind.

In step C), the drying of the coating composition applied to the kraft base paper is performed while the kraft base paper coated with the coating composition passes through the deck and tunnel of the CI printing machine. At this time, the temperature of the deck and the tunnel is 100 ℃, the distance between the deck and the tunnel is about 15 ~ 20m, it is preferable that the time for the kraft paper to pass through the deck and the tunnel is about 10 ~ 15 seconds.

Finally, in step D), the kraft moisture-proof paper produced in step C) is inserted into a conventional umbilical machine for manufacturing a belt, cut according to a preset standard, and then printed and sealed to the required part. To prepare a sugar belt according to the invention.

[Example]

A coating composition consisting of 46% by weight of styrene acrylic emulsion, 37% by weight of water, 7.7% by weight of silicone, 7% by weight of methanol, 1.6% by weight of polyether siloxane copolymer, and 0.7% by weight of polyether siloxane copolymer and hydrophobic silica Was prepared.

At this time, the styrene acrylic emulsion was used as consisting of 15% by weight of a styrene resin having a glass transition temperature (Tg) of 100 ℃ and 85% by weight of 2-ethylhexyl acrylate having a glass transition temperature (Tg) of -50 ℃. It was confirmed that the glass transition temperature of the coating composition was -34°C.

Prepare a kraft paper with a basis weight of 80 g/m ² , apply the coating composition to one side of the kraft paper with a coating amount of 10 to 12 g/m ² using a rubber roller of a CI printing machine, and then dry it to prepare a kraft moisture-proof paper. I did. At this time, the operating conditions of the CI printer were set to a maximum operating speed of 100 m/min and a coating temperature of 100° C., and the work tension was operated at 35 kg of unwind, 45 kg of outfeed, and 35 kg of rewind.

The kraft moisture-proof paper was folded and pasted according to a preset standard, and cut into 35.5 cm in width, 61 cm in length, and 7.5 cm in side width, respectively, to prepare a seoldang zone.

[Performance test]

Each of the sugar strips was filled with 15 Kg of white sugar to prepare 10 samples whose inlet was sealed, and the samples were stored for 15 days under severe conditions of 60% humidity and 40°C, and then the internal condition was checked. As a result, in all samples, no change in sugar formation or discoloration was observed.

In addition, as a result of performing a dissociation test by randomly selecting three of the above samples to discharge all the sugar, and immersing the empty sugar ground in water for a day, it was confirmed that the pulp, which is the material of the kraft paper, can be reproduced by more than 90%.

Finally, a moisture permeability experiment (Cobb Size) was conducted to confirm the moisture-proof effect on the samples. Three of the samples prepared according to the embodiment of the present invention were randomly selected, and each sample was cut into a size of 13 cm×13 cm and used as samples. In addition, as a comparative example, three kraft papers not coated with the desiccant composition were cut into the same size to prepare a sample.

In the moisture permeability test method, the samples of the above examples and comparative examples were respectively added to the moisture permeability test apparatus, and then 100 ml of water was added to the test apparatus, and immersed for about 2 minutes. After taking the sample out of the test apparatus, each weight was measured and the moisture permeability (g/m ² ) was calculated.

As a result, it was found that the sample of Example prepared according to the present invention had an average moisture permeability of 27.9 g/m ² , and that of the comparative example had an average of 32.7 g/m ² . Therefore, it was confirmed that the sugar band prepared according to the present invention has an excellent moisture-proof effect.

Claims (7)

On one or both sides of the kraft paper, 40 to 50% by weight of styrene acrylic emulsion; 35 to 45% by weight of water; 5 to 10% by weight of a physical property supplement; 3 to 10% by weight of a wetting agent; 1 to 3% by weight of a leveling agent; Easy-to-recyclable kraft moisture-proof paper, characterized in that it contains 0.5 to 1% by weight of a defoaming agent and is coated with a moisture-proof layer made of a coating composition having a glass transition temperature (Tg) of -40°C to -30°C.
The method of claim 1, wherein the styrene acrylic emulsion comprises 10 to 20% by weight of a styrene resin having a glass transition temperature (Tg) of 100°C, and 2-ethylhexyl acrylate 80 to 90 having a glass transition temperature (Tg) of -50°C. Kraft moisture proof paper that is easy to recycle, characterized in that it consists of weight percent.
The method according to claim 1 or 2, wherein the physical property supplement is silicone, the wetting agent is ethanol, the leveling agent is a polyether siloxane copolymer, and the antifoaming agent is a polyether siloxane copolymer and hydrophobic silica. Kraft moisture-proof paper that is easy to recycle.
The kraft moisture-proof paper according to claim 1 or 2, wherein the coating composition is applied in an amount of 5 to 20 g/m ² .
On one side of kraft paper having a basis weight of 50 to 140 g/m ² , 15 wt% of styrene resin having a glass transition temperature (Tg) of 100°C and 85 wt% of 2-ethylhexyl acrylate having a glass transition temperature (Tg) of -50°C 46% by weight of a styrene acrylic emulsion consisting of; 37% by weight of water; 7.7% by weight of silicone; 7% by weight of methanol; 1.6% by weight of polyether siloxane copolymer; Easy to recycle kraft moisture-proof paper, characterized in that a moisture-proof layer made of a coating composition comprising a polyether siloxane copolymer and 0.7% by weight of hydrophobic silica is coated with a coating amount of 5 to 20 g/m ² .
A) preparing a kraft base paper having a basis weight of 50 to 140 g/m ² ;
B) 40 to 50% by weight of styrene acrylic emulsion, 35 to 45% by weight of water, 5 to 10% by weight of a physical property supplement, 3 to 10% by weight of a wetting agent, 1 to 3% by weight of a leveling agent, and 0.5 to a defoaming agent Preparing a coating composition consisting of 1% by weight, a glass transition temperature (Tg) of -40 ℃ ~ -30 ℃;
C) coating the coating composition on one side of the kraft paper at an application amount of 5 to 20 g/m ² , and drying it to prepare a kraft moisture-proof paper;
D) cutting the kraft moisture-proof paper according to a preset standard and joining the necessary parts to produce a seoldang zone;
Manufacturing method of a sugar band using a kraft moisture-proof paper, characterized in that it comprises a.
The method of claim 6, wherein the coating of the coating composition in step C) comprises coating at a coating temperature of 90 to 110°C at a rate of 33 to 100 m/min using a rubber roller of a CI (Central Impression) printing machine. A method of manufacturing a sugar band using kraft moisture-proof paper, characterized in that.