KR101392867B1 - The base paper for foraming and a method manufacturing for the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foaming raw paper used for manufacturing disposable containers requiring heat insulation, cold keeping and heat insulation. Since the foaming agent according to the present invention has an optimum water content, smoothness and air permeability (porosity) so that the foamable composition can be uniformly foamed, a uniform foamed layer (air layer) is formed when the foamable composition is foamed by coating .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base paper for foaming and a method for manufacturing the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foaming raw paper used for manufacturing disposable containers requiring heat insulation, cold keeping and heat insulation.

A typical paper cup, which is a disposable container, is generally manufactured by cutting a sheet of paper, rolling it into a circular shape, adhering it to the lower end of the paper cup, and then fixing the upper and lower ends thereof in a circular shape. Since the paper cup thus formed is composed of a piece of paper, heat or cool air is easily transmitted to the user when it resembles a hot tea, water, or ice cream.

Therefore, in order to enhance the warmth, coldness and thermal insulation of the paper cup, a method of manufacturing a paper cup with a double or triple structure or using a cup holder outside the paper cup has been proposed.

However, the paper cups having a double or triple structure are complicated in manufacturing process and cause a waste of paper. In addition, the method of using a separate cup holder also causes a waste of paper, and when the cup holder is broken, the function itself can not be performed.

On the other hand, there has been proposed a technique of improving the warmth, coldness and thermal insulation of a paper cup by preparing a paper by coating a foamable composition and then cutting the paper into a paper cup. The foamed composition is foamed by applying heat to a paper cup coated with the foamable composition to form an air layer, thereby achieving a warmth, cold holding, and heat insulating effect. However, such a paper cup has a problem in that it is difficult to obtain a desired effect of warmth, cold storage and heat insulation because it has a limitation in uniformly foaming the foamable composition.

In order to solve the above problems, it is an object of the present invention to provide a foamable foaming agent capable of uniformly foaming a foamable composition and a method for producing the same.

In order to achieve the above object, the present invention provides a raw paper for foaming, which is obtained by mixing monofilament pulp with long fiber pulp and having a water content of 7% or more.

At this time, the mixing ratio of the short fiber pulp to the long fiber pulp may be 7: 3 to 9: 1.

In addition, the foaming raw material of the present invention may have a structure in which a single sheet mixed with the short-fiber pulp and the long-fiber pulp is laminated.

On the other hand, the present invention relates to a method for producing a pulp fiber, comprising the steps of: a) mixing monofilament pulp and long fiber pulp; And b) a papermaking step of drying and pressurizing the mixed pulp to form a pulp sheet, wherein in step b), the pulp sheet is pressurized and overweighted over a reference basis weight when forming the pulp sheet. A method for producing a paper sheet is provided.

Here, the basis weight (g / m 2) means the weight per square meter of paper.

Since the foaming agent according to the present invention has an optimum water content, smoothness and air permeability (porosity) so that the foamable composition can be uniformly foamed, a uniform foamed layer (air layer) is formed when the foamable composition is foamed by coating .

Accordingly, when the disposable container is manufactured from the foaming paper of the present invention, the warmth, cold storage and heat insulating properties of the disposable container can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a reference diagram for explaining the foaming paper of the present invention. Fig.
Fig. 2 is an image showing that the foamable composition is foamed in the foaming paper of the present invention.
Fig. 3 is an image showing that the foaming composition is foamed on a conventional foaming paper.

Hereinafter, the present invention will be described.

1. Originals for foaming

In general, disposable containers (for example, paper cups) requiring cold keeping, warmth and heat insulating properties are prepared by applying a foamable composition to the surface of raw paper, shaping the same into a container shape, and then foaming the foamable composition at a certain temperature. At this time, the foamable composition should be uniformly foamed on the surface of the raw paper, so that the container manufactured can have excellent cold storage, warmth, and heat insulation.

However, if the smoothness of the raw paper is low, the foamable composition can not be uniformly applied, resulting in non-uniform foaming or a case where the foaming is severe. Also, when the foaming composition is foamed at a certain temperature, when the water content (moisture content) in the paper is not appropriate, the foaming efficiency is lowered, and the strength of the prepared container is lowered. In addition, if the porosity in the raw paper is not proper, the air can not smoothly move during foaming, resulting in non-uniform foaming.

In order to uniformly foam the foamable composition as described above, it is necessary to adjust the moisture content, smoothness and porosity of the foaming composition so that the foaming composition can be uniformly foamed by recognizing that water content, smoothness and porosity of the foam act as important factors Thereby providing a foil for foaming.

The foaming agent of the present invention is a mixture of monofilament pulp and long fiber pulp, and has a water content of 7% or more. When the moisture content of the foaming base paper is less than 7%, the water efficiency for maintaining the temperature at the time of foaming is insufficient and the foaming efficiency is lowered and the internal strength of the paper is lowered. Therefore, the moisture content of the base paper for foaming is preferably 7% or more, and more preferably 8% or more. At this time, even if moisture is excessively contained in the paper, it may be difficult to exhibit a desired strength. Therefore, the moisture content of the foaming paper is preferably 7 to 9%, preferably 7.5 to 8.5%, more preferably 8%.

The foaming raw material of the present invention is a mixture of monofilament pulp (LBKP) and long fiber pulp (NBKP). The monofilament pulp and the long fiber pulp (NBKP) are mixed so that a pore space may be uniformly distributed in the paper. The mixing ratio is preferably 7: 3 to 9: 1, more preferably 8: 2. The long fiber pulp is a pulp obtained mainly from softwood, and can be defined as having a length of 1 mm or more (specifically, 1 to 5 mm), and monofilament pulp is mainly pulp obtained from hardwood, and can be defined as having a length of 1 mm or less .

The flatness of the surface of the foaming agent of the present invention is 45 sec or more (specifically, 45 to 60 sec) and the flatness of the back surface is 30 sec or more (specifically, 30 to 60 sec) on the basis of the Bekk measurement method so that the foamable composition can be uniformly applied. 40 sec). The smoothness indicates the degree of smoothness of the surface. If the surface of the raw paper is smooth, the foamable composition can be applied with a uniform thickness to form a uniform foam layer (air layer) upon foaming. At this time, It may be different or the same.

The foaming agent of the present invention preferably has an air permeability of 150 to 250 seconds so that the foaming agent can be uniformly foamed when air is smoothly moved during foaming. The air permeability is a measure of the time it takes for air to pass from the surface to the backside of the paper, and is closely related to the porosity of the paper. That is, when the pores in the raw paper are large, the degree of air permeability is high and when the air gap is small, the air permeability is low. If the porosity is too high, the strength of the base paper is lowered. If the porosity is too low, the air can not smoothly move and the foaming efficiency is lowered. Therefore, the foaming agent of the present invention has an air permeability of 150 to 250 sec, which is related to the porosity, so that the foaming efficiency of the foamable composition is enhanced while maintaining the strength of the raw paper.

The foaming agent of the present invention may have a structure in which a single sheet in which short fiber pulp and short fiber pulp are mixed is stacked in a plurality of sheets. That is, as shown in FIG. 1, the first sheet 10, the second sheet 11, the third sheet 12, and the fourth sheet 13 may have a stacked structure of four sheets. At this time, each of the sheets has a moisture content of 7% or more, so that the moisture content is 7% or more even if a plurality of sheets are laminated.

The mixing ratio of the short fiber pulp to the long fiber pulp per sheet is preferably 7: 3 to 9: 1, more preferably 8: 2 Is more preferable. On the other hand, pulp (monofilament pulp and long fiber pulp) constituting each sheet is composed mainly of cellulose and / or hemicellulose.

2. Manufacturing method of foil for foaming

The present invention provides a method for manufacturing a foaming paper comprising a composition process and a papermaking process, which will be described in detail as follows.

a) composition process

The short-fiber pulp and the long-fiber pulp are mixed to produce a pulp raw material. Specifically, the pulp raw material is prepared by extracting monofilament pulp and long-fiber pulp from wood and / or plant by a mechanical or chemical method, respectively, and then subjecting to clear and beating to remove debris. At this time, a pulp raw material can be prepared by adding functional additives (filler, retention agent, etc.) known in the art in order to improve the performance of the pulp raw material. The mixing ratio of the short fiber pulp to the long fiber pulp is preferably 7: 3 to 9: 1 as described above, and more preferably 8: 2.

b) Grassland Process

The pulp raw material is dried and pressed to form a pulp sheet. In this papermaking process, the moisture content and smoothness of the pulp sheet to be formed are controlled, and the papermaking process is characterized in that the pressure is over-weighed when the pressure is applied to increase the smoothness. That is, in order to increase the smoothness, the pressure is higher than the reference pressure. If the pressure for pressurization is increased, the thickness of the pulp sheet is decreased and the workability is lowered, and it becomes difficult to produce the paper having the desired strength. Therefore, the present invention over-weighed more than the standard basis weight to compensate for the thickness that is lost while increasing smoothness. Here, the standard basis weight may vary depending on the manufacturing environment (facilities) and the size of the base paper. The ratio of the overweight basis weight is not particularly limited, but is preferably 10 g / m < 2 > or more, more preferably 10 to 20 g / m < 2 > By using such an overweight basis, the present invention can produce a foaming paper having a surface smoothness of 45 sec or more and a back surface smoothness of 30 sec or more based on the Bekk measurement method.

On the other hand, the mixed pulp is formed into a sheet and is dried by passing through a dryer (heat is generated in the dryer by irradiating steam) in which the drying degree is controlled by steam pressure. At this time, the steam pressure of the dryer is adjusted to be contained in the pulp sheet The moisture content can be controlled. Specifically, in a dryer line in which 1 to 6 dryers are arranged in a row, the steam pressure of the first and second dryers is set to a normal reference pressure (specifically, 3.5 kg / cm 2) The steam pressure is set to be about 0.5 to 1 kg / cm < 2 > At this time, it is possible to set all the steam pressures of the third to sixth dryers to the reduced pressure, or to set the reduced pressure to only a part (the fifth and the sixth dryer) when the moisture content in the pulp sheet is small. By adjusting the steam pressure of the dryer in this way, the present invention can produce a foaming paper having a water content (water content) of 7% or more, preferably 8% or more.

On the other hand, the pulp sheet formed as described above is further subjected to a process such as coating to prepare a foaming raw paper as a final product. Here, the prepared foaming raw paper is wrapped and exposed to the market. At this time, the water loss contained in the raw paper can be further prevented by double wrapping.

Hereinafter, the present invention will be described in detail with reference to examples. However, these examples are for illustrating the present invention specifically, and the scope of the present invention is not limited to these examples.

[ Example ] Manufacture of paper for foaming

A raw material which has undergone a composition process by a method known in the art is formed into a paper with a ratio of a mixture of short fiber pulp (LBKP) and long fiber pulp (NBKP) of 8: 2, Particles and press parts were used to adjust the surface smoothness and thickness in a calendar to prepare a foaming paper having physical properties as shown in Table 1 below. At this time, in the dryer part, the steam pressures of the first to sixth dryers were adjusted as follows. In the press part, the raw paper was prepared with a basis weight over 18 g / m 2 than the reference basis weight.

First dryer steam pressure: 3.5 kg / cm < 2 >

Second dryer steam pressure: 3.5 kg / cm < 2 >

Third dryer steam pressure: 3.0 kg / cm 2

Fourth dryer steam pressure: 2.9 kg / cm 2

Fifth dryer steam pressure: 2.9 kg / cm 2

Sixth dryer steam pressure: 2.6 kg / cm 2

[ Comparative Example ]

The raw paper having physical properties as shown in Table 1 below was prepared through the same procedure as in Example 1 except that the mixing ratio of the short fiber pulp to the long fiber pulp was 6: 4. At this time, in the dryer part, the steam pressure of the first drier to the sixth drier was set at a constant value of 3.5 kg / cm < 2 >

Properties Example Comparative Example Fiber mixing ratio LBKP NBKP LBKP NBKP 8 2 6 4 Basis weight (g / m ² ) 318 300 Thickness (mm) 0.34 0.35 Moisture content (%) 8 5.5 Smoothness (sec) 49 25 30 13 Internal bond strength (kg / cm) 1.8 1.2 Specification (Sec) 248 368 * How to measure physical properties
1. Basis weight: Take a sample of more than 1m in length from the paper roll. Three pieces of 400 mm × 250 mm are cut from the collected samples, and weights are measured with electronic scales, and the basis weight is calculated by the following formula.
@ Basis weight (g / ㎡) = weight / (length × length × number of sheets) (width and length are applied in m unit)

2. Thickness: The sample taken for the above weighing measurement is measured with a thickness gauge under a certain pressure.

3. Moisture content: Measure the weight by cutting 250 mm in length and 200 mm in width in the sample taken for the above-mentioned basis weight measurement. Next, put it in a dryer (temperature: 145 ± 5 ° C), leave it for 15 minutes or longer, remove it from the dryer, transfer it to a desiccator, and allow it to cool down for 15 minutes or more until it reaches room temperature. After measuring the weight of the sample, the water content is calculated by the following formula (KSM ISO 287).
@ Moisture content = (sample weight before drying - sample weight after drying) / sample weight before drying × 100

4. Smoothness: Measure the time required for 10 ml of air to pass between the glass surface and the sample surface using the sample taken for the above weighing measurement (KSM ISO 5627 - Bekk measurement method).

5. Internal bond strength: Measured by applying KST 1329.

6. Air permeability: Measured according to KSM ISO 5636-1.

[ Experimental Example  One]

The foamable composition known in the art was applied to the surface of the raw paper prepared in the above Examples and Comparative Examples, and heat was applied for a predetermined time to form a foam layer (air layer). FIGS. 2 and 3 are photographs of a foam layer formed on the raw paper of Examples and Comparative Examples, and it was confirmed that a uniform foam layer was formed in the raw foaming paper of the present invention (Example) without popping phenomenon (see FIG. 2). On the other hand, the base paper of the comparative example showed a popping phenomenon and the foaming did not occur properly, and it was confirmed that a non-uniform foam layer was formed (see Fig. 3).

[ Experimental Example  2]

After the foaming composition known in the art was applied to the surface of the raw paper prepared in the above Examples and Comparative Examples, the cup was molded. Heat was applied to the molded cup for a certain period of time to form a foamed layer to prepare an article cup. The prepared cup was poured with water at 96 ° C and the surface temperature of the cup was measured with time. The results are shown in Table 2 below.

Elapsed time 1 minute 3 minutes 5 minutes 5 minutes surface temperature difference Example 71.0 DEG C 68.1 DEG C 65.0 DEG C -6.0 DEG C Comparative Example 77.7 ° C 73.1 DEG C 67.3 DEG C -10.4 ° C

Referring to Table 2, it can be seen that the cup prepared in the example of the foaming paper of the present invention has better heat insulation than the cup prepared in the comparative example, and the initial (1 minute) surface temperature is lowered. In addition, it was confirmed that the cup prepared in the Example was superior to the cup made in Comparative Example, and the surface temperature difference was small with time.

10: first sheet
11: second sheet
12: Third sheet
13: fourth sheet

Claims (7)

Wherein the monofilament pulp and the long fiber pulp are mixed, the water content is 7% or more,
Wherein the surface smoothness is 45 sec or more and the back surface smoothness is 30 sec or more based on the Bekk measurement method. Wherein the monofilament pulp and the long fiber pulp are mixed, the water content is 7% or more,
And an air permeability of 150-250 sec. 3. The method according to claim 1 or 2,
Wherein the mixing ratio of the short fiber pulp to the long fiber pulp is 7: 3 - 9: 1. 3. The method according to claim 1 or 2,
Wherein one sheet in which the short fiber pulp and the long fiber pulp are mixed is laminated in a plurality of sheets. a) a step of mixing short fiber pulp with short fiber pulp; And
b) a papermaking step of drying and pressurizing the pulp mixed in step a) to form a pulp sheet,
In the step b), when the pulp sheet is formed by pressurization, it is more than 10-20 g / m < 2 > over the standard basis weight of 170-350 g /
Wherein in step b), the mixed pulp is sheeted and dried through a dryer, and the steam pressure of the dryer is reduced to 2.5-3 kg / cm < 2 >. delete delete

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