KR100371272B1 - Moisture proof paper - Google Patents

Abstract

It is intended to provide a moisture-proof paper which does not contain wax and which can be recycled as old paper.

A moisture proof paper 1 having a matrix 2 and a moisture barrier layer 3, wherein the moisture barrier layer 3 is formed of a resin composition containing a synthetic rubber latex and an acrylic emulsion.

Description

Moisture-proof paper {MOISTURE PROOF PAPER}

The present invention relates to a moisture-proof paper that can be recycled into recycled paper.

As a moisture proof paper, the thing which provided the moisture proof layer and water-proof property by forming a moisture proof layer on a base by extrusion lamination | stacking and bonding together synthetic resins, such as polyethylene, a polypropylene, and a vinyl chloride, is generally used now. have. Such moisture-proof paper can exhibit sufficient function with respect to moisture-proof property, but when it is collected and used as old paper, water decomposability is bad and it is difficult to reuse. Therefore, there was a big problem in terms of resource saving and effective use.

On the other hand, as a recyclable moisture-proof paper, a method of forming a moisture-proof layer on a base by applying a mixture of wax alone or a synthetic rubber-based latex (Spec. And a method for forming a film (Japanese Patent Application Laid-Open No. 2-1671, Japanese Patent Application No. 3-69050) and the like are disclosed. These moisture-proof papers can be reused as used paper because the moisture-proof layer has water degradability.

The recyclable moisture barrier paper may bleed out of the composition wax from the moisture barrier layer, so that when the roll is wound in a roll form, the wax on the surface of the moisture barrier layer contacts the back side of the moisture barrier paper. ) Is attached. As a result, the back side of the moisture proof paper is very slippery, and when the packaging of the moisture proof paper is aligned side by side, it becomes uneven or slips off. Serious problems arise. As described above, there is also a drawback that the package is contaminated by wax bleed out from the surface of the moisture barrier layer.

This invention was developed in view of such a problem, and it aims at providing the moisture proof paper which does not contain the wax which is the cause of the said problem, and is recyclable as old paper.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic sectional drawing which shows the moisture proof paper which concerns on one Embodiment of this invention.

* Explanation of symbols for the main parts of the drawings *

1 dampproof base 2 base 3 dampproof floor

As a means for solving the said subject, this invention is a moisture proof paper which has a base and a moisture proof layer, Comprising: The said moisture proof layer is formed from the resin composition containing a synthetic rubber latex and an acrylic emulsion.

According to such means, by blending a soft synthetic rubber latex having a relatively low glass transition temperature and a hard acrylic emulsion having a relatively high glass transition temperature, the glass transition temperature of the resin composition constituting the moisture barrier layer is moisture-proof and degradable. It is possible to set it as 15 degreeC or more and 40 degrees C or less harmonized in high dimension. As a result, recycling as an old paper can be made easy, maintaining the moisture proof property which is a basic performance of a moisture proof paper.

In addition, since wax is not blended as in the conventional moisture-proof paper, the problem caused by the bleeding out of the wax on the surface of the moisture-proof layer, that is, the slipping of the package or contamination can be prevented.

Moreover, the resin composition which forms the said moisture proof layer can also contain a granular filler further. The term "granular" here means literally granular state, specifically, a pillar shape, a candy shape (金 平 糖 狀, confeito [Portuguese]), a sphere shape (球狀), a barrel shape (樽 狀) ), But it does not include flat plates, flaky plates, or Jangbong statues. By mix | blending such a filler, the permeation area of the water vapor in a moisture proof layer can be made small, and as a result, moisture resistance can be improved. Moreover, since the filler to mix | blend in a moisture proof layer is granular, when the said moisture proof paper is sheared into small pieces at the time of recycling, the problem which damages a blade by a filler can be reduced.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail with reference to drawings. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows the moisture proof paper which concerns on one Embodiment of this invention. The moisture proof paper 1 of FIG. 1 is comprised from the base 2 and the moisture proof layer 3.

The branch material constituting the matrix 2 is not particularly limited, and various branch materials can be used. However, in consideration of recyclability, it is preferable to disperse in water by mechanical decomposition, for example, chemical pulp such as hardwood kraft pulp, softwood kraft pulp, or mechanical pulp Examples thereof include upper-quality paper, heavy paper, single-kraft kraft paper, biplane kraft paper, and kraft paper. The weight of the base 2 is not particularly limited, and may be appropriately selected depending on the purpose of about 30 to 300 g / m 2.

The moisture proof layer 3 is formed from the resin composition of a specific composition. The resin composition which comprises the moisture proof layer 3 mainly contains a synthetic rubber latex and an acrylic emulsion. The mixing ratio of the synthetic rubber latex and the acrylic emulsion is preferably set to 50: 100 to 100: 50 by weight. It is soft when the blending ratio of the acrylic emulsion is smaller than the above range, and the water decomposability and blocking are poor. On the contrary, when the blending ratio of the acrylic emulsion exceeds the above range, it is hard and moistureproof. Because it falls out.

Moreover, it is good to set the glass transition temperature of the resin composition which forms the moisture proof layer 3 to 15 degreeC or more and 40 degrees C or less. If the glass transition temperature is smaller than the above range, the stretching force is increased to increase the stretching force. The stretching force is a resistance to the shear force received during decomposition, and the density is high, so that it is difficult to separate and disperse, and the degradability is very poor. On the contrary, when the glass transition temperature exceeds the above range, it is very hard and brittle and the stretching force is small, so that the decomposability becomes very good, but the moisture resistance, in particular, the moisture resistance during bending becomes worse. Therefore, the glass transition temperature of the resin composition which comprises the moisture proof layer 3 needs to be in the said range, More preferably, it is 20 to 30 degreeC.

Specific examples of the synthetic rubber latex include styrene butadiene latex, methacrylate butadiene latex, acrylonitrile butadiene latex, and the like, but have good water resistance and good elongation, resulting in cracking caused by cutting. Styrene butadiene latex, which is hard to form (i), is suitable. Here, the polymerizable monomer mainly consists of styrene and 1,3-butadiene, but other monomers copolymerizable with styrene and 1,3-butadiene can be used within the scope of not impairing the object of the present invention. Do. Other monomers copolymerizable with styrene and 1,3-butadiene include (a) aromatic vinyl monomers such as α-methylstyrene, vinyltoluene, pt-butyltoluene, and chlorostyrene, (b) methyl (meth) acrylate, and (meth). Ethyl acrylate, propyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, ( (Meth) acrylic acid ester monomers such as 2-hydroxyethyl methacrylate and hydroxypropyl (meth) acrylate, cyanic group-containing ethylenically unsaturated monomers such as (c) (meth) acrylonitrile, and (d) glycine acrylate Glycidyl esters of ethylenically unsaturated acids such as dill and glycidyl methacrylate, (e) glycidyl ethers of unsaturated alcohols such as aryl glycidyl ethers, (f) (meth) acrylamides, and N-meth Tyrol (meth) acrylamide, N-methyrol (meth) acrylic (Meth) acrylamide type monomers, such as mead and N-butoxymethyl (meth) acrylamide, etc. are mentioned, These polymerizable monomers can be used individually or in combination of 2 or more types.

As said acrylic emulsion, the copolymer system, such as an acrylic copolymer and acrylic styrene copolymer which copolymerized styrene and a styrene derivative, acrylic acid (methacrylic acid), acrylic acid (methacrylic acid) ester, etc. can be used specifically ,. By mixing and using such an acrylic emulsion in synthetic rubber latex, glass transition temperature can be easily controlled in the said objective range.

It is possible to mix | blend a granular filler further with the resin composition which forms the said moisture proof layer 3. Specific examples of such fillers include: (a) inorganic fillers such as calcium carbonate, talc, barium sulfate, titanium oxide, kaolin, (b) acrylic resin beads, styrene resin beads It is possible to use one kind or two or more kinds of organic fillers such as polyethylene resin beads and urethane resin beads. As mentioned above, moisture-proofing property can be improved by mix | blending a filler.

As for the particle size of the said filler, 3 micrometers or more and 30 micrometers or less are suitable. If the particle size of the filler is smaller than the above range, the effect of improving moisture resistance is less. On the contrary, if the particle size exceeds the above range, irregularities occur on the surface of the moisture barrier layer 3, and the surface of the moisture barrier layer 3 This is because the convex portion may damage the contents and cause a problem such as damaging the blade during shearing.

Now, the manufacturing method of the moisture proof paper 1 is demonstrated. First, a filler is dispersed in a mixture of a synthetic rubber latex and an acrylic emulsion to form a resin composition constituting the moisture barrier layer 3. At this time, if necessary, water-soluble resins such as starch and polyvinyl alcohol may be used as the protective colloid, and dispersants such as polycarboxylic acid, antifoaming agents, surfactants, and color tone composition agents are added. It is possible to do The moisture proof layer 3 is formed by coating the resin composition thus formed on the substrate 2 and drying it. Since drying temperature is enough to give the amount of heat in which a resin composition is fully formed into a film, what is necessary is just the drying conditions equivalent to general coated paper. In addition, it is preferable to apply water to the surface on the opposite side to the moisture proof layer 3 of the base 2 in order to prevent curl.

As for the coating amount of the resin composition for forming the said moisture proof layer 3, the range of 5-50 g / m <2> is suitable for conversion of solid content, and the range of 10-30 g / m <2> is especially suitable. . If the coating amount is less than 5 g / m 2, the moisture-proof property is greatly deteriorated. If the coating amount is more than 50 g / m 2, the improvement of moisture permeability is a limit point, which is uneconomical.

As mentioned above, although it does not specifically limit as a facility for coating a resin composition, For example, an air knife coater, a bar coater, a roll coater, a blade coater, a gate roll coater, etc. can be used. In particular, coating methods for scraping coating surfaces such as blade coaters, bar coaters, and air knife coaters are suitable because they tend to promote smoothness of the surface of the moisture barrier layer 3.

In addition, the moisture proof paper of this invention is not limited to the said embodiment, For example, it is also possible to form the moisture proof layer 3 on both surfaces of the base 2.

Hereinafter, although this invention is demonstrated based on an Example, it cannot be overemphasized that this invention is limited based on description of this Example.

Example 1

A coating solution is prepared by mixing 100 parts by weight of SBR (Tg; -10 ° C) and 50 parts by weight of an acrylic emulsion (Tg; 65 ° C), and coating the coating solution with 20 g / m 2 on a known surface having a weight of 75 g / m 2. The moisture proof paper of Example 1 was obtained.

Example 2

The moisture-proof paper of Example 2 was obtained like Example 1 except having mixed 75 weight part of acrylic emulsion.

Example 3

The moisture-proof paper of Example 3 was obtained like Example 1 except having mixed 100 weight part of acrylic emulsion.

Example 4

The moisture-proof paper of Example 4 was obtained like Example 1 except having mixed 75 weight part of SBR and 100 weight part of acrylic emulsion.

Example 5

A moisture-proof paper of Example 5 was obtained in the same manner as in Example 4 except that 50 parts by weight of SBR was mixed.

Example 6

A moisture proof paper of Example 6 was obtained in the same manner as in Example 4 except that SBR 40 parts by weight were mixed.

Example 7

A moisture-proof paper of Example 7 was obtained in the same manner as in Example 1 except that 40 parts by weight of the acrylic emulsion was mixed.

Example 8

The moisture-proof paper of Example 8 was obtained like Example 1 except having mixed 20 weight part of acrylic emulsion.

Comparative Example 1

A moisture-proof paper of Comparative Example 1 was obtained in the same manner as in Example 1, except that a coating solution containing only SBR was used.

Comparative Example 2

A moisture-proof paper of Comparative Example 2 was obtained in the same manner as in Example 1 except that a coating solution containing only an acrylic emulsion was used.

[Evaluation of Characteristics]

Using the moisture-proof paper of Examples 1 to 8 and Comparative Examples 1 to 2, the glass transition temperature of the resin composition constituting the moisture-proof layer was measured, and the moisture permeability and degradability were evaluated by the method described below. Table 1 shows.

(1) How to measure the moisture permeability

The water vapor transmission rate was measured according to JIS-Z-0208 (B method). The unit of the numerical value shown in Table 1 is g / m <2> * 24h.

(2) Evaluation method of degradability

1.5 g (0.3% pulp concentration) of the sample was added to 500 ml of water, and the sample was dissociated at room temperature for 3 minutes (voltage 60V) using a domestic knife (MX-1200G manufactured by National). After scooping up the paper with a standard sieve (mesh 28 (590 μm)) and drying it with a printer heater (150 ° C. for about 10 minutes), the remaining resin on the surface was visually checked to obtain 1 mm or less. , 1 mm to 5 mm were evaluated in three steps with Δ and 5 mm or more.

Resin composition evaluation SBR Acrylic emulsion Tg Breathability Degradable Example 1 100 50 15 26 Example 2 100 75 22 28 Example 3 100 100 28 32 Example 4 75 100 33 36 Example 5 50 100 40 39 Example 6 40 100 44 43 Example 7 100 40 11 22 △ Example 8 100 20 3 19 △ Comparative Example 1 100 0 -10 15 × Comparative Example 2 0 100 65 73

Since moisture permeability is excellent at about 40 or less moisture permeability, as can be seen from Table 1, the moisture-proof paper of Examples 1 to 8 satisfies moisture permeability and degradability at the same time.

As explained above, according to the moisture proof paper of this invention, it is possible to make the glass transition temperature of the resin composition which comprises a moisture proof layer into 15 degreeC or more and 40 degrees C or less where moisture resistance and decomposability harmonize in high dimension, As a result, the basic performance of a moisture proof paper While retaining phosphorus moisture resistance, it becomes easy to recycle as old paper. In addition, since wax is not compounded as in the conventional moisture-proof paper, problems caused by the bleed-out of the wax, that is, slippage and contamination of the package can be prevented.

Claims (4)

In the moisture proof paper which has a base and a moisture proof layer, The moisture proof layer is formed of a resin composition containing a synthetic rubber latex and an acrylic emulsion. The moisture-proof paper of Claim 1 in which the compounding ratio of a synthetic rubber latex and an acrylic emulsion is 50: 100-100: 50 by weight ratio in the resin composition which forms the said moisture proof layer. The moisture-proof paper of Claim 1 or 2 whose glass transition temperature of the resin composition which forms the said moisture proof layer is 15 degreeC or more and 40 degrees C or less. The moistureproof paper of Claim 1 or 2 in which the resin composition which forms the said moisture proof layer contains a granular filler further.