JPH07133600A - Readily disintegrable and heat-sealing moisture-proof paper - Google Patents

Abstract

PURPOSE:To obtain moistureproof paper extremely excellent in moistureproof, waterproof and heat-sealing properties and disintegration property as a waste paper-recovering property. CONSTITUTION:This moistureproof paper is produced from a process for subjecting waste paper to surface treatment with a mixed solution of an acrylic emulsion having 90-100% get fraction (crosslinking ratio in emulsion panicles) and a wax-based emulsion [mixed ratio of the acryl to the wax is 100:(1-10)] and a process for applying the mixed solution onto the surface of paper and drying the paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture-proof paper, and more particularly to a moisture-proof paper which has a very excellent disintegration property for recovering waste paper and has heat sealability.

[0002]

2. Description of the Related Art Tarpaulin paper and wax paper have long been known as moisture-proof paper, but at present, high-molecular compounds such as polyethylene, polypropylene, and vinyl chloride are coated on paper or laminated. Those that have been given moisture-proof and waterproof properties are generally used. However, although the above-mentioned moisture-proof paper can sufficiently exhibit the moisture-proof property, the disintegration property at the time of collecting and using it as waste paper is extremely poor and it is difficult to reuse it. Therefore, a big problem remains from the viewpoint of environmental problems such as resource saving and effective use.

A paper excellent in moisture-proofing / water-proofing property and excellent disintegration property for recovering used paper and a method for producing the same by using the wax emulsion alone or a mixed solution with a synthetic rubber latex is used. (Tokuhei 3-
No. 10759) and those using a mixed liquid of an acrylic emulsion and a wax emulsion (Japanese Patent Publication No. 2-1671, JP-A-6-200498) and the like are known. However,
Moisture-proof and waterproof paper produced by each method,
Almost all of them are used for packaging, and they have the same performance as existing moisture-proof paper in terms of the amount of moisture and waterproof, but they are not enough to obtain other required qualities. It was

For example, a moisture-proof paper obtained by coating a wax-based emulsion has a drawback that it causes a reduction in the friction coefficient, and further, the moisture-proof property when a crease is made and the disintegration property as recovered paper property are very poor. It was Moisture-proof paper coated with a mixture of synthetic rubber-based latex and wax-based emulsion according to Japanese Examined Patent Publication No. 3-10759 has very poor heat-sealing performance, which is one of the sealing methods, and also has disintegration property when recycled used paper. It wasn't enough. In addition, the poor heat-sealing performance means that an adhesive such as vinyl acetate or gum tape is used to seal the wrapping paper. Therefore, the moisture-proof paper sealed by that method has adhesives, tapes, etc. attached, which adversely affects the disaggregation property at the time of reproduction, which is a major obstacle to practical use when reusing. .

Moisture-proof paper coated with a mixture of an acrylic emulsion and a wax emulsion according to Japanese Patent Publication No. 2-1671 and Japanese Patent Application No. 3-69050 has the following drawbacks. In Japanese Examined Patent Publication No. 2-1671, heat sealability and disintegration property are not mentioned at all, and the mixing ratio is acrylic: wax = 90 to 50:10 to 50 (preferably 70 to 60:
30-40) and a large amount of wax-based emulsion were used, which caused a reduction in the friction coefficient of the moisture-proof paper and was not practical. Also in JP-A-6-200498, similarly, the mixing ratio is acrylic: wax = 100 to 30:30 to 60, the amount of the wax-based emulsion used is large, and the gel fraction is 90% or less. The reduction of the friction coefficient and the disaggregation were insufficient.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is moisture-proof / water-proof and reusable as described above while maintaining the disintegration property as the recoverability of used paper. It is to provide a moisture-proof paper having a heat-sealing property which would cause troubles without it.

[0007]

As a means for solving the above-mentioned problems, the present invention provides an acrylic emulsion and a wax-based emulsion having a gel fraction (crosslinking ratio in emulsion particles) of 90 to 100%. It is preferable to have a surface treatment with a liquid mixture having a mixing ratio of acrylic: wax = 100: 1 to 10), and a step of applying the liquid mixture on a paper surface and drying it. Is obtained.

As the acrylic emulsion that can be used in the present invention, an acrylic copolymer, an acrylic-styrene copolymer copolymer emulsion, a self-crosslinking acrylic copolymer emulsion, or the like can be used. In addition, specifically, acrylic acid esters such as styrene and styrene derivatives, acrylic acid (methacrylic acid) and methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, It is an acrylic copolymer obtained by copolymerizing methacrylic acid ester such as butyl methacrylate.

Further, in the present invention, in order to obtain good disintegration property from the viewpoint of disintegration property of recovered waste paper, it is essential that the gel fraction of the polymer used is in the range of 90 to 100%. It is a condition. If the gel fraction is less than 90%, the polymer layer forming the coating layer will be flexible and stretch at the time of defibration, and this extension will be resistant to the shearing force received during defibration, making it difficult to finely separate and disperse. , The disaggregation becomes very poor. When the gel fraction is 90% or more,
Since the elongation of the polymer layer is small, it is easy to separate and disperse due to the shearing force applied during disaggregation, and a polymer having good disaggregation is obtained. Further, since the gel fraction is increased to reduce the elongation of the polymer, it becomes possible to improve the disintegration property without being influenced by the Tg (glass transition temperature) of the polymer.

Further, in the present invention, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,
Film-forming aid for 2,2,4-trimethylpentadiol-1,3-monoisobutyrate, diethylene glycol mono-tert-butyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monoisobutyl ether acetate, troll, xylol, terpene, etc. It is possible to use agents or plasticizers such as DPO, DBP. Incidentally, these are particularly preferably used in the range of 1 to 10 parts by weight, based on 100 parts by weight of the solid content of the acrylic polymerization / copolymer, and do not adversely affect the quality such as disintegration and form a film. Can be improved. Therefore, it becomes possible to reduce the amount of the wax to be used, which is advantageous for the reduction of the friction coefficient (slippery), and the characteristics as a wrapping paper are easily obtained.

The gel fraction of the polymer used in the present invention (crosslinking ratio within the particle) is determined by using a cross-linking agent such as divinylbenzene, diallyl phthalate, allyl methacrylate, ethylene glycol dimethacrylate, N-methylol acrylamide, etc. It is possible to use those prepared by adjusting the reaction aid, the reaction conditions and the like, and the use is not particularly limited by the production method and the like. The Tg of the polymer is
If it is too high, the film-forming property is poor, and if it is too low, the polymer layer becomes tacky and causes blocking and the like. Considering these, it is preferable to use the one in the range of 0 to 70 ° C.

As the wax emulsion used in the present invention, known wax emulsions such as paraffin wax emulsion and polyethylene wax emulsion can be used. In particular, the paraffin wax emulsion has large water repellency and can be adjusted in moisture permeability. Is preferred and preferred. It is also possible to adjust using two or more kinds of wax emulsions. The composition of the acrylic emulsion and the wax emulsion is
The weight ratio is 100 parts by weight of the acrylic emulsion,
The wax-based emulsion is 1 to 10 parts by weight. If it is less than 1 part by weight, good moisture resistance cannot be obtained, and if it is more than 10 parts by weight, the coating layer becomes very brittle and the moisture resistance at the time of bending is poor, and the friction coefficient extremely decreases, causing trouble. There is a problem that occurs.

The coating amount of the above-mentioned coating liquid on paper is preferably ³ to 25 g / m ² by a conventional method, and particularly 5 to 20 g / m ²
It is preferable that When the coating amount is less than 3 g / m ^2, the quality such as moisture resistance and heat sealability is poor, and when it is more than 25 g / m ² , the cost such as drying ability is high, which is disadvantageous in manufacturing. In addition, the coated base paper to be used has a lower coating amount when the coated surface has a dense surface with high smoothness and air permeability or a base paper with a high size is used. Good moisture resistance can be obtained. For example, paper or coated paper having a glossy surface is particularly preferable. Further, the drying temperature is not particularly limited, but it is preferable to set the melting point of the wax to be used or a temperature higher than that, and from the viewpoint of the drying time, empirically drying at 70 ° C. to 150 ° C. In this case, the above-mentioned effects are exhibited.

Further, in the present invention, a PVA containing an anti-slip agent or an anti-slip agent on the surface of the base paper opposite to the coated surface of the above-mentioned mixed solution for the purpose of preventing slipperiness and curling.
A known material such as starch and starch may be used for coating.
The moisture-proof paper of the present invention comprises a mixture of an acrylic emulsion and a wax emulsion having a gel fraction in the range of 90 to 100%, which is applied to the surface of the paper to form an incompatible wax in the coating layer. In addition, the polymer coating in the coating layer has a gel fraction of 90% or more and uses a polymer film with a small elongation.
Easy to separate and disperse, can be disintegrated within 15 minutes with Tappi standard disintegrator, and can have disintegration property comparable to uncoated paper such as PPC paper, recovering waste paper compared to conventional polyethylene laminated paper etc. Very good and practical.

Further, depending on the blending amount of wax and the coating amount,
It is possible to adjust the moisture vapor transmission rate and the friction coefficient, and it is easy to make the quality equivalent to that of polyethylene laminated paper. In addition, this moisture-proof paper has been given a heat-sealing performance, which is one of the sealing methods, and can be heat-sealed at a lower temperature than polyethylene-laminated paper that is commonly used, which reduces the packaging cost. It is also advantageous in terms of aspects.
Therefore, it is not necessary to perform sealing using a conventional adhesive such as vinyl acetate or tape such as gum tape, and therefore, practical reuse can be smoothly performed.

[0016]

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.
Incidentally, the Tg (glass transition temperature) of the polymer of the emulsion in Examples and Comparative Examples described later is the catalog value (theoretical value) of each chemical company. Table 1 shows the results of the moisture resistance (moisture permeability), disintegration property, heat sealability, and coefficient of static friction of Examples and Comparative Examples.

Example 1 Cybinol X-59 (trade name) having a gel fraction of polymer of 98%
1-607E-17 (made by Saiden Chemical Co., Ltd .: styrene-acrylic emulsion, Tg: 20 ° C.) and trade name Cybinol X-591-607E-18 (made by Saiden Chemical Co., Ltd .: wax emulsion) at a solid content ratio. Mix to 100: 7 (= acrylic: wax), solid content 40%
The coating liquid was adjusted so that The obtained coating liquid was added to 75
Coated on g / m ² single-sided kraft paper with a Meyer bar, 130 ℃
And dried for 30 seconds to obtain a moisture-proof paper having a coating amount of 12.1 g / m ² . As shown in Table 1, the moisture-proof paper obtained as described above had very good moisture-proof property and heat-sealing property. In addition, the disintegration property was evaluated using a Tappi standard disintegrator.
It became a single fiber state completely in a minute and was very good. The elongation at break of the polymer coating, which is greatly related to the disintegration property, was measured and found to be 62%. This result shows that the time required for disaggregation of kraft paper, which is a coated base paper, is 8 minutes, and the time required for disaggregation of PPC paper, which is a representative of non-coated paper, is 10 minutes. This result is comparable to the disintegration property of coated paper, demonstrating that the recycling of waste paper is extremely practical.

[0018] except that the coating amount of Example 1 was from 12.1 g / m ² and 15.1 g / m ² in the same manner as in Example 1 to prepare a moisture-proof paper. As shown in Table 1, the obtained moistureproof paper has moistureproofness, heat sealability,
The disaggregation was good. It was also possible to obtain a lower moisture permeability by increasing the coating amount as compared with Example 1.

Example 3 In exactly the same manner as in Example 1 except that the emulsion obtained in Example 1 and the paraffin wax emulsion were mixed so that the solid content ratio was 100: 4 (= acrylic: wax). A moisture-proof paper having a coating amount of 12.1 g / m ² was prepared. As shown in Table 1, the obtained moisture-proof paper was excellent in moisture-proof property, heat-sealing property and disintegration property. In addition, by reducing the amount of wax compared to Example 1,
It was also possible to increase the coefficient of static friction.

Comparative Example 1 Newcoat S-33 (trade name) having a polymer gel fraction of 13%
Using 00 (Shin-Nakamura Chemical Co., Ltd .: styrene-acrylic emulsion, Tg: 10 ° C.) and trade name WEL-2 (Konishi Co., Ltd .: wax emulsion), under the same conditions as in Example 1. , Coated and dried to prepare a moisture-proof paper. The moisture-proof property (moisture permeability) and heat-sealing property of the obtained moisture-proof paper were good as shown in Table 1. However,
The disintegration property required a disintegration time of 60 minutes to completely become a single fiber state, and the disintegration property was very poor. Further, when the elongation at break of the polymer coating relating to the disintegration property was measured, the elongation was 504%, and the elongation at break of the polymer film having good disaggregation was, for example, 62% in Example 1. That is, it is considered that the large elongation becomes resistance to the shearing force at the time of disaggregation, which makes it difficult to separate and disperse, resulting in poor disaggregation.

Comparative Example 2 A commercially available polykraft paper laminated with 18 μm polyethylene (common name: Polycraft, manufactured by Lintec Co., Ltd.) was similarly measured. Water vapor transmission rate is 36.5g / m ² / 24h
The heat-sealing heating conditions required heating at 100 ° C. for 5 seconds for the moisture-proof layer surface and moisture-proof layer surface and at 120 ° C. for 3 seconds for the moisture-proof layer surface and non-moisture-proof layer surface. Also,
As for the disintegration property, lumps of polyethylene and fibers were observed even after 60 minutes of disintegration, and it was confirmed that the disintegration property was poor.

Comparative Example 3 A commercial product having a coating layer composed of a methyl methacrylate / butadiene copolymer and paraffin wax, which corresponds to the product of Japanese Examined Patent Publication No. 3-10759 (trade name: NEW moisture-proof paper, Oji Chemical Co., Ltd.) Studies on the Ltd.), processing that was subjected to various performance evaluation in the same manner as in example 1, the moisture permeability was 58.4g / m ² / 24hr. In addition, disaggregation requires 20 minutes to become a single fiber state, and about 60 minutes for the moisture-proof layer to separate and disperse.
I needed a minute. This is better than polyethylene laminated paper, etc.
It was far inferior to non-coated paper such as 3 and PPC paper. In addition, the heating conditions for heat sealability are
When the moisture-proof layer surface and the moisture-proof layer surface are at 100 ° C for 5 seconds, there are many variations in the sealing state between the moisture-proof layer surface and the non-moisture-proof layer surface.
Measurement at 5 ° C. for 5 seconds or less was impossible, and the heat sealing performance was very poor.

[0023]

[Table 1]

Moisture-proof / moisture-proof in the table (* 1) is the evaluation result of the moisture-proof layer surface and the moisture-proof layer surface, and moisture-proof / non-moisture-proof shows the evaluation result of the moisture-proof layer surface and the non-moisture-proof layer surface. (* 2) Polyethylene thickness (μm). (* 3) Heat sealing is not possible under conditions of 150 ° C and 5 seconds or less. (* 4) The fibers become monofilament after 20 minutes of disaggregation, but about 60 minutes of disaggregation time was required for the moisture-proof layer to separate and disperse.

The tests and evaluation methods used in the examples and comparative examples are as follows. (1) Moisture Permeability Measured according to JIS Z 0208 moisture vapor proof packaging material moisture permeability test (constant temperature and humidity conditions: 40 ° C., 90% RH). (2) Disintegration property (waste paper recoverability) Using a standard disintegrator (using Tappi standard disintegrator: 3000 rpm) indicated in JIS P 8209 Handmade paper adjustment method for pulp test, about 2.5 cm square in normal temperature tap water The disintegration was carried out by adding an amount of the used paper of 3 to a pulp concentration of 3%, and the disintegration time until the used paper completely became a pulp-like aggregate of single fibers was measured. As the evaluation method, the liquid state after disaggregation and the fiber state after the handmade sheet was prepared were visually determined.

(3) Heat-sealing property Using a sealer manufactured by Tester Sangyo Co., Ltd., press pressure is 1 kg.
In the case of / cm ² , the heating conditions (temperature and time) for complete sealing were measured. The heat-sealing surface of the sample was measured for two types, that is, a moisture-proof layer surface and a moisture-proof layer surface, and a moisture-proof layer surface and a non-moisture-proof layer surface. (4) Elongation of polymer coating A polymer coating (length 200 mm, width 12 mm) was pulled under the conditions of 20 ° C. and 65% RH using a tensile tester, and the elongation at break was measured. (5) Static friction coefficient According to JIS P 8147 Friction coefficient test method for paper and board,
It was measured. The moisture-proof layer surface and the moisture-proof layer surface were measured and evaluated.

(6) Gel Fraction (Intraparticle Crosslinking Ratio) The gel fraction was measured in the following order. The emulsion was dried at 80 ° C to produce a polymer coating. Pre-weighed polymer coating in toluene
It was soaked for one day and filtered using a filter. The insoluble portion after filtration was dried under reduced pressure and then dried at 80 ° C. to measure the weight. The gel fraction was calculated by the following calculation formula.

[0028]

EFFECTS OF THE INVENTION The moisture-proof paper obtained by the present invention is provided with moisture-proof / waterproof and heat-sealing performance while maintaining good disintegration performance, and can be reused by utilizing existing waste paper recycling equipment. It will be possible.

Claims (1)

[Claims] 1. An acrylic emulsion 1 having a gel fraction (crosslinking ratio in emulsion particles) of 90 to 100%.
Moisture-proof paper with easy disintegration and heat-sealability, which is surface-treated with a mixed liquid containing 1 to 10 parts by weight of a wax emulsion with respect to 00 parts by weight.