JP2006257583A - Laminated paper and its laminated paper - Google Patents

Abstract

[Problem] To be used as a packaging material in the food field, medical field, and electronic material field 7, to improve the cosmetics and the like, and after appropriately printing on a laminating paper, laminating processing is excellent in moisture resistance and waterproofing. The present invention provides a paper and a laminated paper excellent in laminating suitability and printability provided thereto.
A laminated paper characterized in that a coating liquid mainly composed of a pigment is coated on one or both sides of a paper at an absolutely dry coating amount of 2.0 to 6.0 g / m ² per side. In addition, a laminated paper characterized in that one side or both sides are laminated after printing on one side or both sides of the laminated paper.
[Selection figure] None

Description

  The present invention relates to a laminated paper used as a packaging material in the food field, medical field, and electronic material field, and a laminated paper used therein, and more specifically, after appropriately printing on one side or both sides in order to improve cosmetics. Further, the present invention relates to a laminated paper excellent in moisture resistance and waterproof property obtained by laminating a laminated paper, and a laminated paper not requiring an anchor coating agent and excellent in laminating suitability and printability.

  Conventionally, packaging materials used in food fields such as snacks, frozen foods, liquid containers, medical fields, electronic materials, etc. have been processed with resin on one or both sides, that is, laminated, in order to improve strength and confidentiality. Many of them are processed, and those having excellent laminate adhesiveness are required so that there is no trouble of peeling the laminate when molding a package or cup.

  In addition, it has been demanded that the packaging material to be laminated is enhanced in cosmetics so as to inspire customers to purchase. For this reason, it is common for laminated paper to be surface treated to improve printability, but it has been well known that the surface treatment of laminated paper is closer to no treatment and the laminating adhesion is higher. (See, for example, Patent Document 1).

  Conventionally, application of a coating liquid mainly composed of a pigment to improve the cosmetics improves the printability, but the laminate adhesion is significantly reduced. For this reason, it is common to maintain laminating adhesion by applying a generally known imine-based or isocyanate-based anchor coating agent and then laminating, and there are many processing steps, including anchor coating agents. This is a cost factor.

As the surface treatment on one side or both sides of a conventional printing base paper, an absolute dry coating amount per side is 1.0 g / m ² or more, preferably 2.0 g / m ² or more. The coated paper is coated with an absolute dry coating amount of 10.0 g / m ² or more to improve printability, so-called cosmetics after printing.
Japanese Patent No. 2626949

  It is an object of the present invention to provide a laminate paper that does not use an anchor coating agent and that does not deteriorate the laminate adhesion during lamination, and that is suitable for printing. It is to be.

As a result of intensive studies on the above problems, the present inventor has arrived at the invention of a laminated paper of the present invention and a laminated paper obtained by laminating the laminated paper.
That is, in the surface-treated laminate paper of the present invention, in the surface treatment, the coating amount is controlled within a certain range for the coating liquid containing pigment as a main component. The pigment is controlled at 0 to 6.0 g / m ² , and the pigment is preferably at least one of various kaolins and various calcium carbonates.

  Further, the present invention is a laminated paper characterized in that one side or both sides are laminated after printing on one side or both sides of the laminated paper.

  The laminated paper according to the present invention is provided with a coating layer mainly composed of a pigment in a normal process in the surface treatment of the paper machine process, on one side or both sides as required, and in a range not accompanied by a decrease in laminate adhesiveness. By applying this surface treatment, it is possible to omit the anchor coating agent application step, and without reducing printability and without lowering the laminate adhesion during laminating. It improves workability and reduces the cost of eliminating the need for an anchor coat processing process, and improves process operability, such as not degrading laminate adhesion, and prevents deterioration in the quality of final packaging materials and suitability. There is a great economic effect on manufacturing.

  The laminated paper of the present invention may be single-layer paper or multi-layer paper, but a paper layer is formed on the felt of a paper machine, and in the case of multi-layer paper, a paper layer is further laminated, and this is repeated. To produce two or more layers of laminated paper. The laminated paper is squeezed with a press part, dried with a pre-dryer part, subjected to the surface treatment according to the present invention with a coater part, re-dried with an after-dryer part, and laminated through a machine calendar. Manufacture paper.

  In the paper making of the present invention, the pulp used as a raw material is not particularly limited. For example, chemical pulp such as NUKP, LUKP, NBKP, LBKP, mechanical pulp such as TMP, CTMP, CGP, RGP, GP, SCP, newspaper Well-known materials such as used paper pulp such as magazines, office paper, information paper, cardboard and paper box can be used alone or in combination of two or more as desired. In the case of multilayer papermaking, each layer may have the same composition or a different composition.

  Like the conventional paper, the base paper is made by adding a filler such as clay, white carbon, amorphous silica, talc, titanium oxide, and calcium carbonate to the paper as appropriate. Also, general publicly known papermaking chemicals such as yield improvers, rosin sizing agents, internal sizing agents such as emulsion sizing agents, paper strength enhancing agents, water-proofing agents, and UV protection agents are added, and publicly known papermaking machines Made in The basis weight of the base paper should be a basis weight appropriately adapted to the purpose of use, and is not limited.

  Examples of the coating apparatus for coating the surface treating agent in the present invention include a blade metalling size press, a rod metalling size press, a gate roll size press, a gate roll coater, a shim sizer, a blade coater, a rod coater, and a bar coater. A coating apparatus usually used in the field of coated paper production, such as a rod blade coater and an air knife coater, can be used as appropriate and is not limited.

  The pigment used in the coating solution to be surface-treated in the present invention is not particularly limited. For example, purified natural mineral pigments such as various kaolins, talc and pulverized calcium carbonate, and composite synthetic pigments such as satin white. And synthetic pigments such as plastic pigments. Among these pigments, at least one of various kaolins or various calcium carbonates is preferable in the present invention.

  Examples of the starch used in the coating liquid include ordinary starch, oxidized starch, etherified starch, esterified starch, enzyme-modified starch, and cold water-soluble starch obtained by flash drying them.

  Further, as a thickener used as a coating solution, water-soluble polymers such as carboxymethylcellulose, sodium alginate, methylcellulose, hydroxyethylcellulose, casein, sodium polyacrylate, polyacrylate, styrene maleic anhydride copolymer And inorganic polymers such as silicates.

  As binders other than starch used in the coating solution, various copolymer latexes such as styrene-butadiene, acrylic, and vinyl acetate, polyvinyl alcohol, sodium polyacrylate, polyethylene oxide, polyacrylamide, urea, melamine / Examples thereof include water-soluble synthetic products such as formalin resin, polyethylenimine, polyamidepolyamine / epichlorohydrin, natural products such as wax, casein, and soybean protein, and those obtained by cationizing these.

  In addition, various commonly used auxiliary agents such as known and publicly used dispersants, antifoaming agents, water-proofing agents, colorants, etc., and those obtained by cationizing these various auxiliary agents may be used as needed. Well, not limiting.

In the present invention, the coating amount of the coating solution to be surface-treated is preferably 2.0 to 6.0 g / m ² absolutely dry per one side. If the coating amount is less than 2.0 g / m ² which is absolutely dry per side, the laminating adhesiveness at the time of laminating is good, but the ink deposition property at the time of printing is inferior. In addition, if the coating amount exceeds 6.0 g / m ² per side, the adhesion of the laminate during laminating will be significantly reduced, resulting in poor laminating adhesion, resulting in poor operability during laminating and laminating. Product rate is significantly reduced and uneconomical.

  In the present invention, it is needless to say that the surface treatment may be single-sided or double-sided as required, and printing and laminating may be single-sided or double-sided as necessary. In addition, it is needless to say that the laminated paper of the present invention can be printed after being subjected to the surface treatment according to the present invention and before laminating, and further after being laminated on one or both sides of the laminated paper. However, there is no limitation to methods such as offset printing, gravure printing, flexographic printing, and the like.

  Examples of the resin to be laminated on the laminated paper of the present invention include those based on polyethylene resin, polypropylene resin, polyester resin, polycarbonate resin, or a mixture thereof, particularly melt extrusion coating properties and films. From the viewpoint of formability, those mainly composed of a polyethylene resin, a polypropylene resin or a mixture thereof are preferred.

Examples of polyethylene resins preferably used in the present invention include low density polyethylene resins, high density polyethylene resins, linear low density polyethylene resins, copolymers of ethylene with α-olefins such as propylene and butylene, ethylene Is a copolymer of acrylic acid, methacrylic acid, acrylic acid methyl ester, methacrylic acid methyl ester, etc., and a mixture thereof, and has various densities and melt flow rates (hereinafter referred to as JIS K 6760 melt flow). Although the rate is simply abbreviated as MFR), those having a molecular weight and molecular weight distribution can be used. Usually, the density is 0.90 to 0.97 g / cm ³ and the MFR is 0.1 to 50 g / 10 minutes, preferably the density is 0.90 to 0. .94 g / cm ³ , MFR 0.3-35 g / 10 min, molecular weight in the range of 20,000-250,000 These can be used alone or in admixture of two or more.

The polypropylene resin preferably used in the present invention is a polypropylene resin, a random polypropylene resin, a random polypropylene resin obtained by copolymerizing 1 to 10 mol% of an ethylene component with propylene as a main component, and a mixture thereof. Density, melt flow rate (hereinafter, melt flow rate defined in JIS K 6758 is simply abbreviated as MFR), molecular weight, and molecular weight distribution can be used. Usually, a density of 0.88 to 0.91 g / cm ³ , Those having a MFR of 10 to 45 g / 10 min, preferably MFR of 15 to 25 g / 10 min can be used alone or in admixture of two or more. Moreover, the compound resin which has a polyethylene-type resin and a polypropylene resin as a main component is preferable in order to improve the extrusion coating property of a polypropylene-type resin. As the compound resin, those having a mass ratio of polyethylene resin: polypropylene resin in the range of 1:99 to 35:65 are particularly preferable.

Examples of the polyester resin used in the present invention include polyethylene terephthalate resin, polybutylene terephthalate resin, polyester biodegradable resin, and mixtures thereof, and those having various densities and melt flow rates can be used. Specific examples include polyester resin (trade name: AP-270L, density 0.91 g / cm ³ , melt flow rate = 4 g / 10 min) manufactured by Mitsubishi Chemical Corporation. Moreover, as a polycarbonate-type resin used for this invention, the thing of various grades can be used, However, As a concrete representative example, the polycarbonate resin (brand name: NOVAREX 7022A, low-viscosity type) by Mitsubishi Chemical Corporation is used. Can be mentioned.

  When two or more different grades or types of resins used in the laminate according to the present invention are used in combination, specifically, for example, a combination of two or more polyethylene resins having different densities and melt flow rates, a polyethylene resin and In the case of combined use of polypropylene resin, combined use of polyethylene resin and polyethylene terephthalate resin, etc., those resins are preferably used as a resin composition comprising a compound resin prepared by melting and mixing in advance. As a method for preparing a compound resin by previously melting and mixing two or more different grades or types of resins, a simple melt mixing method, a multistage melt mixing method, or the like can be used. For example, using a extruder, a twin screw extruder, a heated roll kneader, a Banbury mixer, a pressure kneader, etc., a predetermined amount of a resin to be used in combination, and optionally various additives such as an antioxidant and a lubricant. In addition, the method of pelletizing the mixture after melting and mixing is advantageously used. When the resin to be used in combination is not directly used as a compound resin but is directly added to the melt extruder in the state of simple mixing and melt extrusion coating is applied, the adhesion between the base paper and the resin layer, the mutual mixing of the resin, molding Problems often occur in terms of workability.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Further, “parts” and “%” shown in the examples represent parts by mass and mass% unless otherwise specified.

A pulp slurry containing the following pulp and internally added chemicals was prepared, and a base paper having a basis weight of 350 g / m ² was made into a base material. The paper machine used was a long net paper machine with a surface layer, a five-layer paper machine with a core layer, and a two-layer paper machine with a back layer, and was made at a speed of 128 m / min. Each layer was sprayed with 0.9 g / m ² of commercially available acetylated potato starch by spraying.

<Surface>
LBKP (Drainage 380 mlcsf) 80 parts NBKP (Drainage 400 mlcsf) 20 parts Commercial talc 5 parts Commercial rosin sizing agent 0.05 parts Commercial sulfuric acid band 0.4 parts Basis weight 50 g / m ²

<Core layer>
LBKP (freeness 390 ml csf) 100 parts commercial rosin sizing agent 0.05 parts commercial sulfuric acid band 0.4 parts basis weight 250 g / m ²

<Back layer>
LBKP (freeness 380 mlcsf) 80 parts NBKP (freeness 400 mlcsf) 20 parts Commercial rosin sizing agent 0.05 parts Commercial sulfuric acid band 0.8 parts Basis weight 50 g / m ²

Subsequently, a surface-treatment coating liquid having the following composition is prepared on the base material prepared as described above to a B-type viscosity of 1750 mPa · s, and an absolutely dry coating amount of 6.0 g / m per side with a rod-on coater. After coating so as to be ² , it was calendered after drying to obtain a single-side coated laminated paper.

<Surface treatment coating solution>
Commercially available high white fine kaolin 20 parts Commercially available high white primary kaolin 40 parts Commercially available heavy calcium carbonate 10 parts Commercially available light calcium carbonate 30 parts Commercially available polyacrylic acid-based dispersant 0.25 parts Commercially available latex binder 15 parts Commercially available phosphate esterified starch 2 .5 parts commercially available carboxymethylcellulose thickener (CMC) 0.2 parts commercially available calcium stearate 0.2 parts commercially available printing suitability agent 0.3 parts sodium hydroxide adjusted to pH 9.8

  Subsequently, the single-sided coated laminated paper obtained above was solid-printed with red ink on the coated surface using a RI printing suitability printing machine.

Further, on the solid printing surface of the single-side coated laminated paper obtained as described above, a low density of 22 μm thickness at a set temperature of 290 ° C. after corona discharge treatment (56 W · min / m ² ) by extrusion laminating method. Polyethylene was laminated to obtain a single-side coated laminated paper of Example 1.

The single-sided coating of Example 2 was carried out in the same manner as in Example 1 except that the surface treatment coating solution prepared in Example 1 was coated so that the dry coating amount per side was 5.6 g / m ^2. A laminated paper was produced, and a single-side coated laminated paper of Example 2 was produced in the same manner as in Example 1.

Single-sided coating of Example 3 in the same manner as in Example 1 except that the surface treatment coating solution prepared in Example 1 was applied so that the dry coating amount per side was 4.3 g / m ^2. A laminated paper was produced, and a single-side coated laminated paper of Example 3 was produced in the same manner as in Example 1.

Single-sided coating of Example 4 in the same manner as in Example 1 except that the surface treatment coating solution prepared in Example 1 was applied so that the dry coating amount per side was 3.1 g / m ^2. A laminated paper was produced, and a single-side coated laminated paper of Example 4 was produced in the same manner as in Example 1 using the laminated paper.

Single-sided coating of Example 5 in the same manner as in Example 1 except that the surface treatment coating solution prepared in Example 1 was applied so that the dry coating amount per side was 2.0 g / m ^2. A laminated paper was produced, and a single-side coated laminated paper of Example 5 was produced in the same manner as in Example 1 using the laminated paper.

(Comparative Example 1)
Single-sided coating of Comparative Example 1 in the same manner as in Example 1 except that the surface treatment coating solution prepared in Example 1 was coated so that the dry coating amount per side was 12.8 g / m ^2. A laminated paper was produced, and a single-side coated laminated paper of Comparative Example 1 was produced in the same manner as in Example 1.

(Comparative Example 2)
The single-sided coating of Comparative Example 2 was carried out in the same manner as in Example 1 except that the surface treatment coating solution prepared in Example 1 was applied so that the dry coating amount was 8.2 g / m ² per side. A laminated paper sheet was prepared, and a single-side coated laminated paper sheet of Comparative Example 2 was prepared in the same manner as in Example 1.

(Comparative Example 3)
Single-sided coating of Comparative Example 3 in the same manner as in Example 1 except that the surface treatment coating solution prepared in Example 1 was coated so that the dry coating amount per surface was 1.7 g / m ^2. A laminated paper was produced, and a single-side coated laminated paper of Comparative Example 3 was produced using the laminated paper in the same manner as in Example 1.

(Comparative Example 4)
The surface-treated coating solution prepared in Example 1 was not applied, and the base material made in Example 1 was directly extruded and laminated in the same manner as in Example 1 to produce a laminated paper of Comparative Example 4. A laminated paper of Comparative Example 4 was produced in the same manner as in Example 1.

  The laminated paper and laminated paper produced in Examples 1 to 5 and Comparative Examples 1 to 4 were evaluated by the following evaluation method, and the results are shown in Table 1.

(Printing inking property)
Using a RI printing aptitude printing machine, solid ink was printed with red ink (DIC soybean oil ink, 0.15 cc) on the laminated paper prepared in Examples 1 to 5 and Comparative Examples 1 to 4, and printing was performed. The sensory evaluation was performed on the sex. ○ indicates a good state with good ink transfer and no ink unevenness. X indicates that ink transferability is poor and ink unevenness is remarkable. Δ indicates an intermediate state between ○ and ×. Further, ◯ △ or △ × indicates intermediate states of ◯, Δ, and ×.

(Laminate adhesion)
The laminated paper was torn by hand, and the laminate film was peeled off, and the behavior of the laminate film was observed for sensory evaluation. ○ is a state in which the laminate film at the tearing part has little thread pulling or no interfacial peeling, and is difficult to peel off and is accompanied by destruction of the paper substrate. Δ indicates that the laminate film at the tearing part has a lot of stringing and elongation or peeling at the interface, and if it is carefully peeled off, it can be partially peeled without breaking the paper substrate. X indicates a state in which the laminate film of the peeled portion is well stretched or peeled off at the interface, and can be peeled off relatively easily without breaking the paper substrate. ○ △ or Δ × indicates an intermediate state of each of ○, Δ, and ×. In the state of Δ to ×, there is a risk that the laminate film may be peeled off when the laminated paper is used as a packaging material. The result must be ○ or ○ △.

Rating:
From Table 1, Comparative Examples 1 and ^{2 in} which the absolute dry coating amount exceeds 6.0 g / m ² is a result that the laminate adhesion is remarkably inferior although the printing inking property is good. Further, Comparative Examples 3 to 4 in which the absolute dry coating amount was less than 2.0 g / m ² or the surface treatment coating solution was not applied were printed on the surface even though the laminate adhesiveness was very good. The result is inferior.

On the other hand, Examples 1-5 which are in the range of the coating amount absolutely dry 2.0-6.0 g / m < ² > turned out to be a result with favorable printing inking property and good lamination adhesiveness. did.

  INDUSTRIAL APPLICABILITY The present invention can be used for a laminated paper having good printability and excellent laminating adhesion, no need for an anchor coating agent before laminating, and excellent processing operability and economy.

Claims (2)

A laminated paper characterized in that a coating liquid mainly composed of a pigment is provided on one or both sides of a paper on a dry coating amount of 2.0 to 6.0 g / m ² per side.   A laminated paper characterized in that after printing on one or both sides of the laminated paper according to claim 1, one or both sides are laminated.