JP5415309B2 - Moisture-proof paper - Google Patents

Description

The present invention relates to a recyclable moisture-proof paper having excellent disaggregation and moisture resistance.

In general, a moisture-proof paper used for a newspaper base paper or a wrapping paper for a copy paper is widely used in which paper is coated with an olefin polymer such as polyethylene or polypropylene. The moisture-proof paper coated with this olefin polymer has the advantages of being excellent in moisture resistance and processability and being low in cost. However, when trying to reuse this as a recycled material, the film strength of the moisture-proof layer is too strong, so the pulping process does not sufficiently disaggregate with a disintegrator, and the olefin resin layer detached from the paper becomes a film. The remaining recycled paper has bleeding and irregularities, making it impossible to recycle used paper.

In recent years, as a recyclable moisture-proof paper, a moisture-proof paper coated with an emulsion composed of a synthetic rubber latex and a wax emulsion, or a synthetic rubber latex, a wax emulsion, and a resin emulsion has been proposed. These moisture-proof papers have excellent moisture resistance and recyclability. However, since the coating liquid is an emulsion, a long drying facility is required and productivity is poor.

In recent years, a moisture-proof paper coated with a moisture-proof thermoplastic resin composition mainly composed of amorphous polyalphaolefin (hereinafter abbreviated as APAO), a tackifier resin, and a wax has been proposed (Japanese Patent Laid-Open No. 9-316252). And JP-A-11-158330). This moisture-proof paper is excellent in moisture-proof property and disaggregation, and has an advantage that it can be produced at a low cost because it mainly comprises inexpensive APAO. However, since APAO used as a main component is non-crystalline and soft, the moisture-proof paper is easy to tack, and if the tack is suppressed, the moisture-proof layer is easily broken when bent, and it is difficult to balance various physical properties.

JP-A-9-316252 JP 11-158330 A

The present invention has been made against the background of the above-described prior art, and provides a moisture-proof paper that is excellent in disaggregation, moisture resistance, and recyclability, inexpensive and excellent in productivity.

As a result of intensive studies to solve the above problems, the inventors of the present invention have an ethylene-acetic acid having a melt flow rate (MFR) of 1 to 100 g / 10 min and a vinyl acetate content of 1 to 15% by weight. 20 to 70% by weight of vinyl copolymer (A), 20 to 40% by weight of adhesive resin (B) made of terpene resin, and wax (C) 10 to 10 selected from paraffin wax, polyethylene wax, and polypropylene wax Use recyclable moisture-proof paper obtained by applying 40% by weight [however (A) + (B) + (C) = 100% by weight] as an essential component to a paper coated with a thermoplastic resin composition. It was found that the above problems can be solved.
Moisture-proof paper having a melting point of the wax (C) of 100 to 170 ° C. is preferred.

Proof paper of the present invention has a conventional olefin-based resin composition superior moistureproof paper was coated with moisture barrier properties, also recyclability moisture emulsion coating type or hot melt Coated down Gutaipu proposed recently Excellent disaggregation equivalent to paper. Furthermore, since inexpensive EVA is used as the base polymer, recyclable moisture-proof paper can be supplied at low cost.

In the thermoplastic resin composition used for the moisture-proof paper of the present invention , a low MFR and low vinyl acetate content ethylene-vinyl acetate copolymer (hereinafter abbreviated as “EVA”) ( A ) is used as a base polymer. . These polymers have lower mechanical strength than olefin polymers used in conventional moisture-proof paper. For this reason, the film strength of the thermoplastic resin composition containing this polymer as a base polymer can be kept low, and disaggregation by a disaggregator is enabled in the pulping process during recycling. Moreover, since this polymer has appropriate hardness and flexibility, it is easy to balance various physical properties required for the thermoplastic resin composition for moisture-proof paper.

Here, the MFR will be described in detail. MFR is generally used when expressing the fluidity of a resin. The method for obtaining MFR is to place the material in a cylinder with an orifice of 2.1 mm in diameter and 8 mm in length, extrude the molten material under a load of 2,160 g at 190 ° C., and calculate the weight of the material that flowed out in 3 minutes. It is measured and converted to the number of grams per 10 minutes to obtain the MFR value. That is, the larger the MFR, the better the fluidity (see JIS K6760).

For thermoplastic compositions;
The MFR of EVA (A) used for the thermoplastic resin composition of the moisture-proof paper of the present invention is 1 to 100 g / 10 minutes, and the vinyl acetate content is 1 to 15% by weight. Here, the MFR is preferably 1 to 50 g / 10 min.

The tackifying resin ( B ) in the thermoplastic resin composition only needs to have an effect of increasing the disaggregation property of the thermoplastic resin composition. For example, a terpene resin, an aliphatic resin, an alicyclic resin Resin, aromatic resin, coumarone-indene resin, rosin and its derivatives. Examples of terpene resins include terpene resins, aromatic modified terpene resins, terpene phenol resins, and hydrides thereof. As the tackifier resin ( B ), any of the above may be used, and among these, terpene resins and alicyclic resins are preferable because of their excellent moisture resistance. The tackifying resin ( B ) can be used alone or in admixture of two or more. The terpene-based resin is, for example, polymerization of terpene monomers such as α-pinene, β-pinene, dipentene or the like and aromatic monomers in an organic solvent in the presence of a Friedel-Craft type catalyst, or It is a (co) polymer obtained by further hydrogenation after polymerization. Specifically, trade names “YS Resin PX”, “YS Resin TO”, “Clearon”, “YS Polystar”, “Mighty Ace”, etc., manufactured by Yasuhara Chemical Co., Ltd. may be mentioned. In addition, examples of the alicyclic resin include a product name “Escollet 1202” manufactured by Tonex Co., Ltd.

The preferable softening point of tackifying resin ( B ) is 70-180 degreeC, More preferably, it is 100-160 degreeC. When the softening point is less than 70 ° C., tackiness is likely to occur, and when the processed moisture-proof paper is recycled, the dryer tends to have a pitch in the drying process. On the other hand, when the temperature exceeds 180 ° C., the moisture-proof layer is easily broken when the moisture-proof paper is folded.

The blending ratio of the tackifier resin ( B ) in the thermoplastic resin composition is 5 to 70% by weight, preferably 10 to 70% by weight, and more preferably 20 to 50% by weight. When the blending ratio of the tackifying resin in the composition is less than 5% by weight, the disaggregation property is deteriorated. On the other hand, when the blending ratio exceeds 70% by weight, the moisture-proof layer is easily cracked when bent.

As the wax (C) of the present invention, those having the effect of lowering the melt viscosity and increasing the softening point of the thermoplastic resin composition of the present invention are used. Examples of such wax (C) include paraffin wax, microcrystalline wax, carnauba wax, polyethylene wax, and polypropylene wax. Among these, paraffin wax, polyethylene wax, and polypropylene wax are preferable. The said wax (C) can be used individually or in mixture of 2 or more types. The melting point of the wax (C) is preferably 100 to 170 ° C, more preferably 110 to 160 ° C. When a wax having a melting point of less than 100 ° C. is used, it becomes easy for the dryer to be pitched in the recycling drying process. On the other hand, if it exceeds 170 ° C., handling becomes difficult.

The blending ratio of the wax ( C ) in the thermoplastic resin composition is 5 to 50% by weight, preferably 10 to 30% by weight. When the processed moisture-proof paper is recycled when the blending ratio of the wax ( C ) is less than 5% by weight, the dryer tends to have a pitch in the drying process. On the other hand, if it exceeds 50% by weight, the moisture-proof layer tends to break when the moisture-proof paper is folded.

The softening point of the thermoplastic resin composition is preferably 100 to 200 ° C, more preferably 120 to 180 ° C. When the softening point of the composition is less than 100 ° C., the dryer tends to have a pitch in the drying process of recycling the moisture-proof paper. On the other hand, when it exceeds 200 ° C., the coating property on paper is deteriorated.

The thermoplastic resin composition can be obtained by mixing EVA ( A ), adhesive resin ( B ) and wax ( C ) having the above specific physical properties, but within a range not inhibiting the effects of the present invention. In order to prevent pitch adhesion, polyolefin such as polypropylene, polystyrene, AS resin (styrene-acrylonitrile copolymer), thermoplastic elastomer and the like may be added. Further, within the scope of the purpose of the present invention, if necessary, fillers such as calcium carbonate, titanium oxide, barium sulfate, talc, clay, carbon black, anti-aging agent, antioxidant, ultraviolet absorber, flame retardant, Additives such as colorants, plasticizers or oils can be blended. These additives are not particularly limited, and conventionally known additives used for thermoplastic resin compositions are usually used.

In preparing the thermoplastic resin composition, the method of mixing the components is not particularly limited, and all the components may be added together and mixed, or each component may be added stepwise.

About moisture-proof paper; The kind of paper which coats the said thermoplastic resin composition is not specifically limited. The basis weight of the paper is not particularly limited, but is preferably 50 to 200 g / m ² .

For example, a roll coater, a slot orifice coater, a head coater, an extrusion coater or the like that uses the resin composition by heating and melting (hot melt) can be used as a method for coating the thermoplastic resin composition on paper. However, it is not limited to these, and any method may be used. The coating amount is not particularly limited, but is preferably 10 to 50 g / m ² . The adjustment of the coating amount is performed by a generally used method such as a Mayer bar.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Hereinafter, parts and% are based on weight unless otherwise specified. Moreover, physical property evaluation was measured by the following method.

(1) Melt flow rate (MFR): described in the text.
(2) Tensile breaking strength: measured in accordance with JIS K6760.
(3) Softening point: Measured according to JIS K6714.
(4) Melting point: The usual method was followed.
(5) Tack: The tack of the moisture-proof paper sample surface was evaluated by a finger touch test.

(6) Disintegration property 10 g of moisture-proof paper sample was cut into 1.5 cm × 1.5 cm, put into a disaggregator with 500 mL of warm water at 40 ° C., stirred for 30 minutes, re-papered, and visually observed on the surface of the recycled paper. The presence of the resin was confirmed, and the disaggregation property of the resin in the moisture-proof paper sample was evaluated. The evaluation criteria are as follows. ◎: Very good, ○: Good, ×: Impossible (7) Bleeding resistance temperature Similar to the above-mentioned disaggregation test, after re-making the moisture-proof paper sample, the recycled paper is put in a dryer at a temperature of 100 to 160 ° C. (10 (10 ° C increments) for 10 minutes and dried, and the presence or absence of bleeding due to resin residue was confirmed. The upper limit temperature at which bleeding did not occur was defined as the bleeding resistance temperature. (8) Moisture permeability Moisture permeability was measured by the cup method (based on JIS Z0208). The moisture permeability was measured for flat plate and cross fold. Cross-folding was measured after folding the sample from the center to a cross and making a crease by reciprocating a 2 kg roll twice. The unit of moisture permeability is g / m ² after 24 hours.

Reference Example 1 The following were prepared as the component ( A ). ( A-1 ); EVA, manufactured by Mitsui DuPont Co., Ltd., trade name “P-1207” (MFR: 12 g / 10 min, vinyl acetate content 12%) ( A-2 ); EVA, prototype (MFR: 200g / 10min, vinyl acetate content 10%)

Reference Example 2 The following were prepared as the component ( B ). ( B-1 ); aromatic modified terpene resin [manufactured by Yasuhara Chemical Co., Ltd., trade name “YS Resin TO-125”, softening point 125 ° C.] ( B-2 ); terpene resin [manufactured by Yashara Chemical Co., Ltd., trade name] “Clearon P-148”, softening point 148 ° C.] ( B-3 ); alicyclic resin [manufactured by Tonex Co., Ltd., trade name “Escollet 1202”, softening point 100 ° C.]

Reference Example 3 The following were prepared as the component ( C ). ( C-1 ): Polyethylene wax [Yasuhara Chemical Co., Ltd., trade name “Neowax L”, melting point 110 ° C.] (C-2) ; Polypropylene wax [Mitsui Chemicals, trade name “Mitsui High Wax NP” −055 ”, melting point 136/145 ° C. (DSC method measurement)] (C-3) ; paraffin wax [manufactured by Nippon Seiwa Co., Ltd., trade name“ paraffin 145 ° F., melting point 64 ° C.]

Example 1 35 parts of EVA ( A- 1), 40 parts of terpene resin ( B- 2) and 25 parts of polypropylene wax ( C- 2) were melt-mixed at 180 ° C. while being manually mixed in a laboratory. Using a head coater manufactured by Meltex Co., Ltd., coating was performed on 100 g / m ² of kraft paper at a coating amount of 22 g / m ² to obtain a moisture-proof paper sample.

Example 2 EVA (A -1) 70 parts to use the terpene resin (B -2) 20 parts of polypropylene wax (C -2) 10 parts was applied to kraft paper of 120 g / m ² Example 1 was performed to obtain a moisture-proof paper sample.

Example 3 A moisture-proof paper sample was obtained in the same manner as in Example 1 except that 20 parts of EVA ( A- 1), 40 parts of terpene resin ( B- 2) and 40 parts of paraffin wax ( C- 3) were used. .

Comparative Example 1 A moisture-proof paper sample was obtained in the same manner as in Example 1 except that 80 parts of EVA ( A- 1) and 20 parts of aromatic-modified terpene resin ( B- 1) were used.

Comparative Example 2 A moisture-proof paper sample was obtained in the same manner as in Example 1 except that 90 parts of EVA ( A- 2) and 10 parts of aromatic-modified terpene resin ( B- 1) were used.

Comparative Example 3 10 parts of EVA (A- 2 ), 20 parts of aromatic modified terpene resin ( B- 1), 30 parts of alicyclic resin (B-3) and 40 parts of paraffin wax ( C- 3) were used. Except that, the same procedure as in Example 1 was performed to obtain a moisture-proof paper sample.

Comparative Example 4 Another moisture-proof paper made by applying APAO thermoplastic resin composition to 75 g / m ² of kraft paper at a coating amount of 20 g / m ² [trade name “New G Y "] was used for the evaluation. The evaluation results of the moisture-proof paper samples of Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Tables 1 and 2.

The moisture-proof paper of the present invention can be supplied inexpensively as a moisture-proof paper for various uses that can be recycled.

Claims (2)

An ethylene-vinyl acetate copolymer (A) having a melt flow rate (MFR) of 1 to 100 g / 10 min and a vinyl acetate content of 1 to 15% by weight, 20 to 70 % by weight, and comprising a terpene resin Adhesive resin (B) 20 to 40 % by weight, and wax (C) 10 to 40 % by weight selected from paraffin wax, polyethylene wax and polypropylene wax [However, (A) + (B) + (C) = 100% by weight] is a recyclable moisture-proof paper obtained by coating a paper with a thermoplastic resin composition. The moisture-proof paper according to claim 1 , wherein the wax (C) has a melting point of 100 to 170 ° C.