JP2920925B2 - Method for producing water-dispersible resin-laminated paper - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excellent method for producing a resin-laminated paper which easily disperses when put into water, and has an ink penetration preventing property and a barrier property.

B. Conventional Techniques A technique for controlling the barrier properties and permeability of paper by applying a water-soluble resin such as polyvinyl alcohol to paper in the form of an aqueous solution has been conventionally performed.

In addition, in sizing paper, the production of water-dispersible paper having the property of disintegrating and dispersing due to the stirring action of a water flow after water absorption and swelling is achieved by significantly reducing the amount of hydrophobic sizing and making a paper using a hydrophilic sizing agent. Has also been practiced in the past.

However, no method has been found for efficiently producing a product having the above-mentioned water-dispersible paper provided with barrier properties and anti-penetration properties.

For example, a conventional method of applying a water-soluble resin to paper in the form of an aqueous solution, when performed on water-dispersible paper, has a large porosity and remarkable permeability, so that a barrier film is formed. The water-dispersible paper used in the present invention is difficult to be treated and the other paper needs to have a certain wet strength, and the strength is significantly reduced when wet. I can not say.

Also, after spraying ultrafine water on one surface of the water-dispersible paper (for example, vibration spraying by ultrasonic waves) or applying a small amount of a hydroalcoholic solution to wet the surface without damaging the shape of the paper, A method of crimping a water-soluble polymer film and heating it as necessary has also been proposed (utility model announcement, 57-52089), but it is complicated by the technique, and when the film is crimped, it tends to wrinkle. Further, since the paper is still wetted to some extent by water, the strength of the water-dispersible paper is reduced, which is not an effective method.

C. Problems to be Solved by the Invention The present invention imparts a barrier property and an anti-penetration property to a water-dispersible paper whose strength is greatly reduced when wet, without impairing its characteristic water-dispersibility. The present invention provides a method for efficiently manufacturing a manufactured product.

D. Means for Solving the Problems The present inventors have conducted intensive studies, and as a result, a polyvinyl alcohol-based resin having both water-soluble or water-dispersible properties and hot-melt properties as a water-dispersible paper. By using a melt extrusion lamination method, it is possible to efficiently produce a laminate of a water-dispersible paper and a water-soluble or water-dispersible polyvinyl alcohol-based resin without causing a decrease in the strength of the water-dispersible paper due to wetting. It was found that the laminate had good water dispersibility, barrier properties, and anti-permeation properties, and the present invention was completed.

That is, the present invention is easily dispersed when put into water,
The present invention relates to an efficient method for producing a resin-laminated paper having an ink penetration-preventing property and a barrier property. Specifically, a polyvinyl alcohol-based resin having both heat melting property and water solubility or water dispersibility is dispersed in water. The present invention relates to a method for producing a laminate by melt-extrusion coating on a non-woven paper. In the extrusion lamination method, for example, taking non-polar polyethylene as an example, `` To extrude such non-polar polyethylene and adhere it to the substrate, the surface is oxidized by air during processing and the A necessary condition is to have an adhesive force, for which the temperature of the molten web exiting the die must be at least 300 ° C. Therefore, polyethylene is naturally heated to at least 300 ° C. in an extruder. , It is necessary to melt-knead. "In contrast, the polyvinyl alcohol resin used in the present invention originally contains a large amount of a hydroxyl group which is a polar group. There is no need to introduce a polar group into the surface by air oxidation, and good adhesive strength can be obtained even when extruded at a relatively low temperature.

From the above, in the resin lamination method of the present invention, a polyvinyl alcohol-based resin is charged into an extruder having a T die, and the resin temperature is 100 to 300 ° C., more preferably
A good resin-laminated paper can be obtained by extruding a web from a T-die at a temperature of 150 to 250 ° C., pressing the water-dispersible paper between a nip roll and a cooling roll, and simultaneously cooling the paper.

If the resin temperature is lower than 100 ° C., the adhesion between the polyvinyl alcohol-based resin and the paper decreases, and if the resin temperature is higher than 300 ° C., the decomposition and gelation of the polyvinyl alcohol-based resin become remarkable, which is not preferable in operation.

The water-dispersible paper used in the present invention has a property of significantly reducing the hydrophobic sizing agent, absorbing water and swelling with paper made using the hydrophilic sizing agent, and then disintegrating and dispersing by the stirring action of the water flow. .

This paper has an air permeability of 10 seconds or less measured in accordance with JIS P-8117 "Test method for paper and paperboard air permeability",
Preferably, it should be 5 seconds or less.

The polyvinyl alcohol-based resin used in the present invention is a polyvinyl alcohol having a reduced saponification degree and a reduced melting point in order to impart a melt extrusion laminating property,
20 mol% or more and 80 mol% or less of the vinyl ester portion are saponified, and more preferably 40 mol% or more and 70 mol% or more of the vinyl ester portion are saponified.

If more than 80 mol% of the vinyl ester moiety is saponified, its melting point becomes high and approaches the thermal decomposition onset temperature, which is not preferable for use.

If less than 20 mol% of the vinyl ester portion is saponified, the hydrophilicity of the polyvinyl alcohol resin is reduced and it is not easily dispersed in water, so that water dispersibility as in this application is required. Can not be used for things.

Further, the polymerization degree of the polyvinyl alcohol-based resin in the present invention is 100 or more, 2000 or less, more preferably 300 or less.
More than 1,000.

If the degree of polymerization is less than 100, the polyvinyl alcohol-based resin becomes a highly sticky trimoty, and cannot be used in the present invention because blocking occurs when it is laminated on paper and then wound up on a roll. If the degree of polymerization is greater than 2,000, the melt viscosity of the polyvinyl alcohol-based resin increases, and the moldability deteriorates, making it difficult to use.

Further, the polyvinyl alcohol-based resin used in the present invention can further draw out its properties, or, for the purpose of imparting another property, by copolymerizing a monomer other than vinyl acetate, or by using a chain transfer agent. It is possible to modify the polymer end. For example, a method of introducing an ionic group into a polyvinyl alcohol-based resin in order to increase the water solubility of the polyvinyl alcohol-based resin is suitable for the purpose of the present invention.

Examples of the ionic group to be introduced include, but are not limited to, a carboxyl group and a sulfone scattering group as an anionic group, and a quaternary ammonium group as a cationic group.

Among them, sulfonic acid-modified PVA and carboxyl group-modified P
VA is often used.

Sulfonic acid-modified PVA is obtained by copolymerizing a monomer containing sulfonic acid or its salt such as allyl sulfonic acid, vinyl sulfonic acid, methacrylate propyl sulfonic acid, N-sulfoalkyl (meth) acrylamide with vinyl acetate and then saponifying. In particular, sodium allyl sulfonate and salts of N-sulfoalkylacrylamide are preferably used.

For example, when sodium allyl sulfonate is copolymerized, the degree of modification is 0.1 to 5 mol%, the degree of polymerization is 200 to 1000, and the degree of saponification is 50.
~ 70 mol% PVA is used.

The carboxyl group-modified PVA may be similarly modified with a carboxyl group or a salt-containing monomer thereof such as (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, and itaconic acid. In particular, modification with itaconic acid or maleic anhydride is preferable. In this case, a modification degree is 0.5 to 5 mol%, a polymerization degree is 200 to 1000, and a saponification degree is 50 to 50.
70 mol% can be used.

Further, the polyvinyl alcohol-based resin, if necessary, further an antioxidant, an ultraviolet absorber, glycerin, a plasticizer such as ethylene glycol, a lubricant, a coloring agent, a filler,
Heat stabilizers and the like can be added. Many other high molecular compounds can also be blended to such an extent that the effects of the present invention are not impaired.

E. Effects and Effects of the Invention According to the production method of the present invention, the water-dispersible paper, whose strength is greatly reduced when wet, has a barrier property and an anti-penetration property without impairing its characteristic water-dispersibility. Can be efficiently manufactured.

Examples of applications of the water-dispersible laminated paper manufactured according to the present invention include, but are not limited to, water-dispersible printed paper, water-dispersible paper structures, and water-dispersible wrapping paper. Not something.

Next, the present invention will be described in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

In each of the following examples, what is simply written as the degree of polymerization was obtained by completely saponifying the used polyvinyl alcohol and measuring the intrinsic viscosity from the aqueous solution.
It is a viscosity average degree of polymerization.

Example 1 A polyvinyl alcohol-based resin having a degree of polymerization of 340 and a degree of saponification of 61 mol% was supplied to a feed port of a single-screw extruder having a screw diameter of 40 mm equipped with a T-die having a die width of 360 mm. Zone 160 ℃, 3rd zone 200 ℃, Die 2
It was extruded under a temperature condition of 00 ° C. and melt-extruded to a thickness of 20 μm on a water-dispersible paper prepared in advance.

The operating conditions during extrusion lamination were good, and the adhesion between the paper and the polyvinyl alcohol-based resin layer was also good.

Further, the obtained laminate (10 cm × 10 cm) was put into 1 piece of water and stirred at room temperature, and dispersed within a few minutes, confirming that it had good water dispersibility.

Further, as a method for evaluating the barrier property and the permeation prevention property of the obtained laminated product, a line was drawn with a commercially available magic ink, and no permeation of the ink was observed, indicating a good permeation prevention property.

Example 2 A polyvinyl alcohol-based resin having a polymerization degree of 590 and a saponification degree of 62 mol% was melt-extruded on a water-dispersible paper with a thickness of 20 μm under the same apparatus and conditions as in Example 1.

Mobility, adhesion, water dispersibility of the obtained laminated paper,
The anti-permeation property was as good as in Example 1.

Example 3 At the time of vinyl acetate polymerization, sodium alisulfonic acid was copolymerized as an ionic copolymer in an amount of 0.4 mol%, and then saponified to obtain a polyvinyl alcohol resin having a polymerization degree of 340 and a saponification degree of 60 mol%. Under the same apparatus and conditions as in Example 1, a 20 μm thick melt-extruded laminate was formed on water-dispersible paper.

Drivability, adhesion, water dispersibility of the obtained laminated paper,
The anti-permeation property was as good as in Example 1.

Comparative Example 1 A commercially available 5% aqueous solution of polyvinyl alcohol having a polymerization degree of 1700 and a saponification degree of 98.5 mol% was applied to water-dispersible paper using a size press, and then dried. During operation, the strength of the paper was reduced, and troubles such as partial adhesion to the roll occurred, resulting in poor operability. Further, when the obtained paper was checked for permeation preventing properties, it was found that ink bleeding was remarkable and the permeation preventing properties could not be imparted very much.

Comparative Example 2 Extrusion lamination was performed using commercially available polyvinyl alcohol having a degree of polymerization of 500 and a saponification degree of 88 mol% under the same apparatus and conditions as in Example 1. However, the thermal fusibility of polyvinyl alcohol was poor, and the apparatus could not be operated. Did not.

Comparative Example 3 Polyvinyl acetate (non-saponified) having a polymerization degree of 500 was extrusion-laminated on water-dispersible paper under the same apparatus and conditions as in Example 1.

The water dispersibility of the obtained laminated paper was poor because polyvinyl acetate had no water dispersibility.

Comparative Example 4 An ethylene-vinyl acetate copolymer (Mitsubishi Yuka, Mitsubishi Polyethylene EVA V40) generally used for paper lamination
1S) was extruded under the same apparatus and conditions as in Example 1, and was melt-extruded and laminated on water-dispersible paper.

The water dispersibility of the obtained laminated paper was poor due to the lack of water dispersibility of the ethylene-vinyl acetate copolymer.

Comparative Example 5 An aqueous solution containing 10% glycerin with respect to polyvinyl alcohol having a polymerization degree of 1700 and a saponification degree of 99.5 mol% was prepared, and a film having a thickness of 20 μm and a water content of 12% was obtained. This film was laminated on a water-dispersible paper and dried. During the drying treatment, the strength of the paper decreased, and troubles such as a part of the laminated paper adhering to the drying roll occurred, and the operability was extremely poor.

Further, when the obtained paper was checked for permeation prevention properties, it was found that ink bleeding was remarkable and the permeation prevention properties were poor.

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Claims (1)

(57) [Claims] 1. A water-dispersible paper having a saponification degree of at least 20 mol% and at most 80 mol% on at least one surface, and an average degree of polymerization of
A method for producing a water-dispersible resin-laminated paper, comprising melt-extruding and laminating 100 to 2,000 polyvinyl alcohol-based resins.