TW201813819A - Raw material sheet used for foamed resin coated paper products and foamed resin coated paper container - Google Patents

Abstract

The present invention relates to the raw material sheet used for foamed resin coated paper products and foamed resin coated paper container, painted the environment-friendly inks, provides excellent appearance due to its smooth foamed surface, wherein the foamed resin layer is formed by heating a thermoplastic resin layer on at least one side, having one or more layer of water-based ink painted portion, wherein the thickness of the foamed resin layer in case of the unpainted is assumed X, and the thickness of the foamed resin layer with one layer of water-based ink painted portion is assumed Y, the foaming inhibition rate represented by the formula [1] is 40% or less. "the foaming inhibition rate (%)"=(1-X/Y)*100 [1] The foamed resin coated paper container is made of the raw material sheet.

Description

Raw material sheet for foaming paper products and foaming paper container

FIELD OF THE INVENTION The present invention relates to a raw material sheet for a foamable paper product and a foamable paper container.

BACKGROUND ART In general, a foamable paper sheet and a foamable paper container are formed by laminating low-density polyethylene on one side of a base paper, and high-density or medium-density on one side of the opposite side. Polyethylene is formed by heating in an oven. The surface of the low-density polyethylene has a printed layer including a decorative pattern, a product name, a company name, a barcode, and the like.

For example, the method of forming the printing layer may be, for example, gravure printing, flexographic printing or the like. Among the inks for gravure printing, it has heretofore been known that a binder component contains a polyamide resin or the like and a cellulose derivative. The ink for gravure printing significantly suppresses foaming of the low-density polyethylene, in the printing portion and the non-printing portion of the printing layer, or in the printing portion and the overprinting portion which is printed on the printing portion, after foaming The thickness of the low density polyethylene will vary. Thereby, the printing portion or the overprinting portion constitutes a concave portion, and a drop occurs, which causes a problem that printing is not clear.

As an ink for improving the unevenness on the surface of the printing layer, Patent Document 1 discloses an oil-based ink containing a coloring agent, a binder resin, and a solvent, and the binder resin contains an urethane resin and a vinyl chloride/vinyl acetate. The copolymer has a mixing ratio of urethane resin:vinyl chloride/vinyl acetate copolymer of 50:50 to 99:1 based on the total weight of the urethane resin and the vinyl chloride/vinyl acetate copolymer. The elongation of the aforementioned binder resin is 400% to 3,000%.

Advance Technical Literature Patent Literature Patent Document 1: Japanese Patent No. 4619445

SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION In the oil-based ink described in Patent Document 1, the surface of the low-density polyethylene after foaming can be kept in a state in which the unevenness is extremely small, and a foam having a smooth printed surface and excellent appearance can be obtained. Paper products. However, since the oil-based ink uses an organic solvent, it is worried about the environment and the operator. Specifically, there are problems such as a residual solvent of the printed matter and a large amount of solvent (VOC) discharged.

The present invention has been made in view of the above circumstances, and provides a raw material sheet comprising a foaming paper container composed of the above-mentioned raw material sheet, and the raw material sheet containing an ink having a small influence on the environment, and a printed layer surface can be obtained. A foaming paper product that is smooth and has an excellent appearance.

In order to achieve the above object, the inventors have found that by using an aqueous ink containing a binder resin and having a urethane resin in a specific ratio, the inventors have made it possible to achieve the above object. The present invention has been completed in a foamed paper product having a smooth printed surface and excellent appearance.

The present invention encompasses the following aspects. [1] A raw material sheet for a foamable paper product, characterized in that it is composed of a paper substrate having a foamed layer which has at least one layer of aqueous ink coating portion on at least one side The thermoplastic resin layer is heated, and the foaming thickness of the foamed layer when the aqueous ink is not applied is X, and when the foaming thickness of the aqueous ink coating portion is Y, the following formula [ The foaming inhibition ratio shown in 1] is 40% or less. [Formula 1] Foaming inhibition rate (%) = (1 - Y / X) × 100 [1] [2] The raw material sheet of [1], wherein the aqueous ink contains a colorant and a binder resin, and The resin solid content of the above-mentioned binder resin contains 30% by mass or more of the urethane-based resin having a glass transition point of -20 ° C or more and 30 ° C or less. [3] The raw material sheet of [1] or [2], wherein the aqueous ink further contains an extender pigment. [4] The raw material sheet of [3], wherein the aforementioned extender pigment is cerium oxide. [5] The raw material sheet according to any one of [1] to [4] wherein the foamed layer further comprises a foaming suppressing portion. [6] The raw material sheet according to [5], wherein the foaming suppressing portion is formed by heating a thermoplastic resin layer having a foaming-inhibiting ink coating portion, and the foaming inhibiting ink contains a glass transition point of 60 ° C In the above resin of 120 ° C or less, the resin accounts for 70% by weight or more of the resin solid content of the binder resin. [7] The raw material sheet according to [6], wherein the resin having a glass transition point of 60 ° C or more and 120 ° C or less is an acrylic resin. [8] A foamable paper container comprising the raw material sheet of any one of [1] to [7].

According to the present invention, it is possible to provide a raw material sheet having a foaming paper container composed of the above-mentioned raw material sheet, and the raw material sheet containing an ink having a small influence on the environment, and a smooth surface and appearance of the printed layer can be obtained. Excellent foaming paper products.

In the embodiment, the present invention provides a raw material sheet for a foamable paper product, which is composed of a paper substrate having a foamed layer, the hair The foam layer is formed by heating at least one layer of the thermoplastic resin layer having one or more aqueous ink coating portions on one surface, and the foaming layer of the foamed layer when the aqueous ink is not coated is set to X, and a layer of aqueous ink is used. When the foaming thickness of the coating portion is Y, the foaming inhibition ratio shown by the following formula [1] is 40% or less.

[Formula 2] Foaming inhibition rate (%) = (1-Y/X) × 100 [1]

According to the raw material sheet of the present embodiment, a foamable paper product having a smooth printed surface and excellent appearance can be obtained. In addition, since an organic solvent other than alcohol is not used, and the alcohol ratio in the solvent is 30% or less, water is used in addition to this, and the environmental load is small compared to the conventional oil-based ink. Further, the aqueous ink used in the raw material sheet of the present embodiment can be colored in the same manner as the aqueous gravure printing method even in the low-coating aqueous flexographic printing method, and vivid printing can be obtained.

<Structure> Figs. 1A and 1B are cross-sectional views schematically showing an embodiment of a raw material sheet of the present invention. Fig. 1A is a view showing a raw material sheet before heat foaming, and Fig. 1B is a sheet showing a raw material after heat foaming. The raw material sheet 10 before foaming according to the present embodiment has the aqueous ink non-coating area A and the aqueous ink coating area B which are disposed adjacent to each other in plan view, and is in accordance with the non-foamed thermoplastic resin layer 2a and the paper substrate 3, The foamed thermoplastic resin layer 2b and the printed layer 1 (the first aqueous ink coating portion 1a and the second aqueous ink coating portion 1b) are laminated in this order. Further, in the foamed raw material sheet 20 of the present embodiment, the foamed layer 2b' is foamed with the printed layer 1 (the first aqueous ink coating portion 1a and the second aqueous ink coating portion 1b). The thermoplastic resin 2b is heated, and is composed of a general foaming portion 4 existing in the aqueous ink non-coating region A and a printing foam portion 5 existing in the aqueous ink coating region B. By the application of the aqueous ink, the printing foam portion 5 can be somewhat suppressed from foaming as compared with the general foam portion 4. In addition, the printing foaming portion 5 is composed of the first printing foaming portion 5a and the second printing foaming portion 5b, and the first printing foaming portion 5a is a region where the first aqueous ink coating portion is exposed on the surface. That is, it is formed in one layer of the aqueous ink coating portion, and the second printing foam portion 5b is formed in a region where the second aqueous ink coating portion is exposed on the surface, that is, in the two-layer aqueous ink coating portion.

In the foamed raw material sheet 20 of the present embodiment, the foaming thickness of the aqueous ink non-coating portion (generally the foaming portion 4) is X, and the water-based ink coating portion of the first layer is foamed. When the thickness is Y, the foaming inhibition ratio represented by the following formula [1] is 40% or less, preferably 39% or less, more preferably 38% or less. When the foaming inhibition rate is within the above range, a printed matter having a smooth boundary between the aqueous ink non-coating portion and the printing layer can be formed, and the printing can be clearly recognized. Further, in the case of the foamed raw material sheet 20 of the present embodiment, when the aqueous ink coating portion is formed by the flexographic printing method (that is, the aqueous ink coating per unit area in the aqueous ink coating portion) When the amount of the cloth is 0.1 g/m ² or more and 6.0 g/m ² or less, the foaming thickness of the aqueous ink non-coating portion (generally the foam portion 4) is set to X, and the layer of the aqueous ink is used. When the foaming thickness of the coating portion is Y, the foaming inhibition ratio represented by the following formula [1] is 30% or less, preferably 29% or less, more preferably 28% or less. In the case where the aqueous ink coating portion is formed by the flexographic printing method, the aqueous ink coating portion is formed by the gravure printing method (that is, the water per unit area in the aqueous ink coating portion). When the amount of ink applied is, for example, 7.0 g/m ² or more and 15.0 g/m ² or less, the amount of ink used is small, so that the foaming inhibition rate can be further reduced.

[Expression 3] Foaming inhibition rate (%) = (1-Y/X) × 100 [1]

As the X and Y, the average value of the measured values of the foamed thickness of each layer of the aqueous ink coating portion can be used. 1A and 1B, a raw material sheet having a two-layer aqueous ink coating portion is exemplified. However, for two or more layers, for example, the foaming thickness of an aqueous ink coating portion such as three or four layers is as long as The foaming thickness of each layer of the aqueous ink coating portion is measured, and the average value is used, and the numerical value is applied to the above formula [1] to calculate the foaming inhibition ratio. For example, in FIG. 1B, when the foaming thickness of the two-layer aqueous ink coating portion is Y', Y' is used instead of Y in the above formula [1], and the foaming inhibition ratio is calculated. can.

Further, the first aqueous ink and the second aqueous ink used in the printing layer may be the same color or different colors.

Further, in the foamed raw material sheet 20 of the present embodiment, the foaming thickness of the one layer of the aqueous ink coating portion is Y, and the foaming thickness of the two-layer aqueous ink coating portion is Y. In the case of the formula [2], the foaming inhibition ratio is 20% or less, preferably 19% or less, and more preferably 18% or less. By making the foaming inhibition rate within the above range, the surface of the printed layer is smooth and the printing can be clearly recognized.

[Formula 4] Foaming inhibition rate (%) = (1-Y'/Y) × 100 [2]

2A and 2B are cross-sectional views schematically showing another embodiment of the raw material sheet of the present invention. 2A is a view showing a raw material sheet before heat foaming, and FIG. 2B is a sheet showing a raw material after heat foaming. 2A and 2B, the same components as those shown in the above-described drawings are denoted by the same reference numerals, and the detailed description thereof will be omitted.

The raw material sheet 30 before foaming shown here is the same as the raw material sheet 10 before foaming shown in FIG. 1A except that the foaming-inhibiting ink coating portion 1c is provided. In other words, the raw material sheet 30 before foaming has the aqueous ink non-coating area A and the aqueous ink coating area B which are disposed adjacent to each other in plan view, and is in accordance with the non-foamed thermoplastic resin layer 2a and the paper substrate 3. The foam layer (foamed thermoplastic resin layer) 2b and the printed layer 1 (the first aqueous ink coating portion 1a, the second aqueous ink coating portion 1b, and the foaming suppression ink coating portion 1c) are laminated in this order. Moreover, the foamed raw material sheet 40 shown here is the same as the foamed raw material sheet 20 shown in FIG. 1B except that the foaming suppressing portion 5c is provided. In other words, in the raw material sheet 40 after foaming, the printing foam portion 5 is composed of the first printing foam portion 5a, the second printing foam portion 5b, and the foaming suppressing portion 5c, and the first printing sheet The bubble portion 5a is formed in a region where the first aqueous ink coating portion is exposed on the surface (that is, a layer of the aqueous ink coating portion), and the second printing foam portion 5b is a region where the second aqueous ink coating portion is exposed on the surface. (that is, the two-layer aqueous ink coating portion) is formed, and the foaming suppressing portion 5c is formed in a region where the foam-inhibiting ink coating portion 1c is exposed on the surface.

In the foamed raw material sheet 40 of the present embodiment, the foaming thickness of the two-layer aqueous ink coating portion is Y', and the foaming thickness of the foaming-inhibiting ink coating portion is Z. In the case of the formula [3], the foaming inhibition ratio is 40% or more, preferably 50% or more, more preferably 60% or more, and still more preferably 65% or more. By setting the foaming inhibition ratio within the above range, a raw material sheet capable of imparting a smooth design surface and excellent designability using irregularities can be obtained.

[Expression 5] Foaming inhibition rate (%) = (1-Z/Y') × 100 [3]

In the above Y' and Z, the average value of the foam thickness measurement values of the second aqueous ink coating portion or the foaming suppression ink coating portion can be used. 2A and 2B, the raw material sheet having the two-layer aqueous ink coating portion is exemplified. However, for the two or more layers, for example, the foaming thickness of the aqueous ink coating portion such as three or four layers is as long as The foaming thickness of the water-based ink coating portion of each layer or the foaming-inhibiting ink coating portion provided thereon may be measured, and the numerical value may be applied to the above formula [3] to calculate the foaming inhibition ratio.

The raw material sheet of the present invention is not limited to the raw material sheet shown in FIGS. 1A to 2B, and the partial structure of the raw material sheet shown in FIGS. 1A to 2B may be changed or deleted within the range in which the effects of the present invention are not impaired. Or, other structures may be further added to the raw material sheets described so far.

For example, the raw material sheet shown in FIGS. 1A to 2B may have two or more layers, for example, three or four layers of aqueous ink coating portions. Among them, the aqueous ink coating portion is preferably two or more layers and eight or less layers. Further, in the raw material sheet shown in FIGS. 1A to 2B, the aqueous ink may be applied to the entire surface of one side and covered with a printing layer, that is, the aqueous ink non-coating portion is not provided. Further, in the raw material sheet shown in FIGS. 1A to 2B, a foamed thermoplastic resin layer may be provided on both surfaces.

Moreover, in the raw material sheet shown in FIG. 2A and FIG. 2B, the foaming suppression ink coating part may be provided in the 1st aqueous ink application part. In this case, in the raw material sheet, when the foaming thickness of the aqueous ink coating portion is set to Y and the foaming thickness of the foaming ink coating portion is Z, The foaming inhibition ratio shown in the above formula [4] is 40% or more, preferably 50% or more, more preferably 60% or more, and still more preferably 65% or more. By setting the foaming inhibition ratio within the above range, a raw material sheet capable of imparting a smooth design surface and excellent designability using irregularities can be obtained.

[Equation 6] Foaming inhibition rate (%) = (1-Z/Y) × 100 [4]

Further, in the raw material sheet shown in FIG. 2A and FIG. 2B, a foaming-inhibiting ink coating portion may be provided in each of the first aqueous ink coating portion and the second aqueous ink coating portion. The foaming inhibition rate at this time can be calculated using the above formula [3] and formula [4], respectively. Further, in the raw material sheet shown in FIGS. 2A and 2B, a foaming-inhibiting ink coating portion may be provided on the aqueous ink non-coating portion. In this case, in the raw material sheet, when the foaming thickness of the aqueous ink non-coating portion is X and the foaming thickness of the foaming ink coating portion is Z, The foaming inhibition ratio shown in the above formula [5] is 40% or more, preferably 50% or more, more preferably 60% or more, and still more preferably 65% or more.

[Expression 7] Foaming inhibition rate (%) = (1-Z/X) × 100 [5]

<Constituent Material> The material constituting the raw material sheet of the present embodiment will be described below.

[Printing Layer] In the raw material sheet of the present embodiment, the thickness of the aqueous ink coating portion before heating is preferably 2 μm or less per layer. By being 2 μm or less, a smooth printing surface can be produced without suppressing foaming. When the aqueous ink coating portion is, for example, two layers, the printed layer after drying is preferably 4 μm or less. For example, when the aqueous ink coating portion is, for example, three layers, the printed layer after drying is preferably 6 μm or less. In addition, when the foam-inhibiting ink coating portion is provided in the raw material sheet of the present embodiment, the thickness of the foam-inhibiting ink coating portion before heating can be, for example, 0.1 μm or more and 2 μm or less, and for example, It is 0.2 μm or more and 1 μm or less. In the thickness after drying of the foaming-inhibiting ink coating portion before heating, the foaming suppressing effect is excellent in the thickness of at least the above lower limit. In addition, in the thickness after drying of the foaming-preventing ink-coating portion before the heating, it is not necessary to print twice or more even in the gravure printing, and the amount of ink used can be suppressed. Further, since it is not necessary to use two printing units, the time and labor required for ink cleaning after use can be saved, and the number of colors that can be used for the aqueous ink of the present embodiment which is low foaming suppression can be maintained in a large amount. .

(Aqueous Ink) The aqueous ink used in the printing layer of the present embodiment is a solvent added to the structure of the aqueous ink coating portion in a dry state. That is, the aqueous ink contains a colorant, a binder resin, and a solvent. Further, in addition to the above, the aqueous ink may contain an auxiliary agent (for example, a polyolefin-based wax such as polyethylene wax; a fatty decylamine, a fatty acid ester, a paraffin wax, a polytetrafluoroethylene (PTFE) wax, a palm wax, or the like. Various ink additives such as various waxes, leveling agents, defoamers, pigment dispersants, and slip agents.

◎ Colorant The colorant may be an inorganic colorant or an organic colorant. For example, the inorganic coloring agent may be exemplified by titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, aluminum hydroxide, talc, clay, kaolin, chromium oxide, cerium oxide, carbon black, aluminum, mica. (mica) and so on. The white colorant is preferably titanium oxide from the viewpoints of coloring power, hiding power, chemical resistance, and weather resistance, and more preferably titanium oxide having a basic surface of the pigment. Aluminum is in the form of a powder or a paste. However, it is preferably used in the form of a paste in terms of handleability and safety, and is suitably selected from the viewpoint of brightness feeling and concentration in the case of using a float type or a non-floating type. Barium sulfate, calcium carbonate, aluminum hydroxide, talc, clay, and kaolin are called body pigments, and are used as extenders for improvement in fluidity, strength, and optical properties. On the other hand, examples of the organic coloring agent include organic pigments or dyes which are generally used in inks, paints, recording materials, and the like. For example, azo, phthalocyanine, anthraquinone, anthraquinone, anthrone, quinacridone, thioindole, dioxazine, isoindolinone, quinine A phthalocyanine, an azomethine azo, a pyrrolopyrroledione, an isoporphyrin or the like. The content of the coloring agent can be appropriately selected in consideration of a desired ink color tone or the like, and can be generally 50% by weight or less based on the total weight of the aqueous ink. The concentration of the colorant.

When the aqueous ink used in the present embodiment is white, the content of the white pigment can be generally 20% by weight or more and 50% by weight or less based on the total weight of the aqueous ink. The pigment content of the ink concentration. The white pigment is preferably titanium dioxide from the viewpoints of shielding properties, pigment concentration, and light resistance. Further, when the aqueous ink used in the present embodiment is colored, for example, the colored pigment contained may be, for example, a colored organic pigment, and a colored inorganic such as iron oxide red, Prussian blue, ultramarine blue, carbon black, or graphite. Pigments, etc. The color pigment is preferably an organic pigment from the viewpoint of color rendering properties and light resistance. The content of the colored pigment can be generally 10% by weight or more and 30% by weight or less based on the total weight of the aqueous ink, and the content of the pigment which can obtain the necessary ink concentration can be formed within the above range.

The aqueous ink used in the present embodiment preferably contains an extender pigment. As will be described later, the aqueous ink used in the present embodiment contains a large amount of urethane-based resin. Therefore, the water-based ink-coated portion after foaming tends to be sticky. However, in the present embodiment, by containing the extender pigment, the amount of the urethane-based resin can be maintained in a large amount, and the water after foaming can be suppressed. The ink coating part is sticky. Further, the brightness, gloss and texture of the foamed paper product after processing can be adjusted.

For example, the aforementioned extender pigment may, for example, be cerium oxide or the like. The cerium oxide can be, for example, a compound known as "synthetic cerium oxide" produced by a known method. A representative manufacturing method for synthesizing cerium oxide includes: a wet method in which an ultrafine powder aqueous citric acid is produced by reacting sodium citrate in which a raw material is high-purity cerium with an acid; or a dry method by using tetrachloro The hydrazine is carried out by combustion hydrolysis in the gas phase.

The cerium oxide used in the present embodiment is not particularly limited to the synthesis method, and examples thereof include untreated cerium oxide (untreated cerium oxide). The particle diameter of the cerium oxide used in the present embodiment is preferably 2 μm or more and 20 μm or less, and more preferably 3 μm or more and 10 μm or less. By using cerium oxide having a particle diameter of at least the above lower limit value, it is possible to prevent the viscosity of the aqueous ink from being improved and to prevent the ink state from being lowered. In addition, by using cerium oxide having a particle diameter of not more than the above upper limit, it is possible to prevent foaming of a low-melting resin film which is a foamed thermoplastic resin during heat treatment at the time of container production. The foam followability of the ink film is deteriorated.

Further, in general, the particle diameter of cerium oxide is measured by a Coulter counter method using a change in resistance, a laser method using light scattering, or the like. In the present embodiment, it means the average particle diameter obtained by the measurement by the laser method.

In the case where the cerium oxide is contained in the embodiment, the content of the cerium oxide is preferably 0.2% by mass or more and 5% by weight or less, more preferably 0.5% by mass or more and 3.5% by mass based on the total mass of the aqueous ink. the following. By setting the content of cerium oxide to the above range, it is possible to adjust the viscosity to be easily treated by the aqueous ink. Further, the brightness feeling and the feeling after processing of the foaming paper product can be adjusted.

◎Binder resin The above-mentioned binder resin contains a urethane resin having a glass transition point of -20 ° C or more and 30 ° C or less, preferably -15 ° C or more and 0 ° C or less, and a resin of the above-mentioned binder resin. The solid component preferably contains 30% or more of the urethane-based resin, more preferably 50% or more, more preferably 70% or more, and particularly preferably 90% or more. By setting the glass transition point of the urethane-based resin to -20 ° C or higher, the occurrence of adhesion can be suppressed, and suppression of foaming can be suppressed by being 30 ° C or lower. Further, "adhesive" generally means that when the ink is printed, dried, and then wound, the raw material sheet has a surface on which the printed layer is adhered to the opposite side. When the amount of the urethane-based resin contained in the binder resin is within the above range, foaming of the thermoplastic resin is hardly suppressed, and a raw material sheet having a smooth printing surface can be obtained.

○ urethane-based resin A urethane-based resin such as a polyurethane resin or a polyurethane urea resin can be selected, and a known urethane-based resin for printing ink can be used. For example, an urethane-based resin obtained by reacting a polymer polyol with a polyisocyanate may be mentioned.

. Polymer Polyol As an example, a polymer polyol which can be used for an urethane resin can be exemplified by PEG (polyethylene glycol), PPG (polypropylene glycol) or PTMG (polyoxytetramethylene glycol). Polyether polyols; ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, Low molecular diols such as methyl pentanediol, hexanediol, octanediol, decanediol, methyl decanediol, diethylene glycol, triethylene glycol, dipropylene glycol, etc. with adipic acid and phthalic acid Formic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, sebacic acid, sebacic acid, dimer acid, etc. Polyester polyols obtained by dehydration condensation of acid or such anhydrides; other polycarbonate diols, polybutadiene diols, addition of bisphenol A to ethylene oxide or propylene oxide Various known polyols such as glycols and dimers. These polymer polyols may be used singly or in combination of two or more. Among them, from the viewpoint of resolubility of the aqueous ink, the polymer polyol preferably contains a polyether polyol, and more preferably contains PEG (polyethylene glycol).

. Polyisocyanate Further, for example, various polyisocyanates which can be used for the urethane-based resin include various known diisocyanates of aromatic, aliphatic or alicyclic groups. More specifically, for example, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-di Benzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, methylphenyl diisocyanate , butane-1,4-diisocyanate, hexamethylene diisocyanate, iso-propyl diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, cyclohexane -1,4-diisocyanate, decyl diisocyanate, isophorone diisocyanate, diazonic acid diisocyanate, dicyclohexylmethane-4, 4'-diisocyanate, 1,3-bis(isocyanatomethyl ester) Cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethyl decyl diisocyanate or a diisocyanate dimer obtained by converting a carboxyl group of a dimer acid to an isocyanate group.

. Introduction of a carboxyl group When a carboxyl group is to be introduced into a resin, a polyol having a carboxyl group can be used. For example, a polyol having a carboxyl group may, for example, be a dimethylol group such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid or 2,2-dihydroxymethylpentanoic acid. Alkanic acid; diamine-type amino acid such as glutamic acid, aspartic acid, lysine, diaminopropionic acid, ornithine, diaminobenzoic acid, diaminobenzenesulfonic acid. These may be used alone or in combination of two or more.

In the production of the polyurethane urea resin, a polymer polyol, a polyisocyanate, and a carboxyl group-containing polyol can be reacted to form a polyurethane resin, and then a urea chain bond can be introduced and synthesized using a chain extender and a reaction stopper. When the urethane-based resin used in the aqueous ink of the present embodiment is a polyurethane urea resin, the coating film is more toughened by having a urea bond, and the coating film property tends to be improved.

. Chain extender Various known amines can be used as the chain extender which can be used for introducing a urea bond. For example, the aforementioned amines may, for example, be 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine , 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-di An amine, a dimer diamine which converts a carboxyl group of a dimer acid to an amine group, or the like. These may be used alone or in combination of two or more. Among them, the chain extender in the present embodiment is preferably an amine having a hydroxyl group, and has a tendency to have good resolubility.

. The reaction stopping agent is exemplified, and examples of the reaction stopping agent include dialkylamines such as di-n-dibutylamine, monoethanolamine, diethanolamine, and 2-amino-2-methyl-1-propanol. Tris(hydroxymethyl)aminomethane, 2-amino-2-ethyl-1,3-propanediol, N-di-2-hydroxyethylethylenediamine, N-di-2-hydroxyethylpropane An amine having a hydroxyl group such as an amine or N-di-2-hydroxypropyl ethylenediamine, glycine, alanine, glutamic acid, taurine, aspartic acid, aminobutyric acid, proline, Monoamine type amino acids such as aminocaproic acid, aminobenzoic acid, aminoisophthalic acid, and aminesulfonic acid. These reaction stoppers may be used singly or in combination of two or more.

. Neutralizing agent In order to make the urethane-based resin such as a polyurethane resin and a polyurethane urea resin soluble in water, it is preferred to neutralize part or all of the carboxyl group in the resin by a basic compound. For example, the aforementioned basic compound may, for example, be sodium hydroxide, potassium hydroxide, ammonia, methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, ethanolamine, propanolamine, diethanolamine, N- Methyldiethanolamine, dimethylamine, diethylamine, triethylamine, N,N-dimethylethanolamine, 2-dimethylamino-2-methyl-1-propanol, 2-amino-2- Methyl-1-propanol, ifolin, and the like. These neutralizing agents may be used singly or in combination of two or more. Among them, the neutralizing agent in the present embodiment is preferably ammonia from the viewpoints of water repellency and residual odor of the printed matter.

. The synthesis method is exemplified by a method for synthesizing an urethane resin such as a polyurethane resin or a polyurethane urea resin, such as an acetone method using an organic solvent which is inert to a isocyanate and a hydrophilic solvent, and a solventless synthesis method in which a solvent is not used at all. Wait. For example, examples of the organic solvent which is inert to the isocyanate and hydrophilic are, for example, ethers such as tetrahydrofuran and dioxane, esters such as ethyl acetate, ketones such as acetone, methyl ethyl ketone and cyclohexanone, and A guanamine such as methylformamide or N-methylpyrrolidone. The organic solvent is usually removed by distillation under reduced pressure (desolvation), and even when it is used without a solvent, in order to accelerate the drying rate, it is preferred to use a solvent having a boiling point lower than that of water. When the solvent is removed, for example, water and a basic compound may be added to the reaction solution.

○ Acrylic resin The above-mentioned binder resin may further contain an acrylic resin. As the acrylic resin, an acrylic resin which can be obtained by radical copolymerization of an acrylic monomer and another monomer copolymerizable with the acrylic monomer can be used.

. The acrylic monomer The acrylic monomer is not particularly limited, and examples thereof include methyl (meth) acrylate (others, either methacrylate or methyl methacrylate). The same applies to the following.), ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, a (meth)acrylic monomer containing an alkyl group such as a cyclohexyl (meth) acrylate; a (meth)acrylic monomer having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate; (methyl) An ethylenically unsaturated carboxylic acid such as acrylic acid; an amino group-containing (meth)acrylic monomer such as dimethylamine ethyl (meth) acrylate or dimethylaminopropyl (meth) acrylate; (methyl) a (meth)acrylic monomer containing decylamine such as acrylamide or ethyl (meth) acrylamide; a (meth)acrylic monomer containing a nitrile group such as acrylonitrile; and a glycidyl group (methyl group) An epoxy group-containing (meth)acrylic monomer or the like such as an acrylate.

. Other monomers copolymerizable with the acrylic monomer, for example, other monomers copolymerizable with the acrylic monomer may be exemplified by aromatics such as styrene, methylstyrene, chlorostyrene, and vinyltoluene. Hydrocarbon-based vinyl monomer; α,β-ethylenically unsaturated carboxylic acid such as maleic acid, itaconic acid, crotonic acid, fumaric acid, citraconic acid; styrene sulfonic acid, vinyl sulfonic acid, etc. Monomer; acid anhydride such as maleic anhydride or itaconic acid; chlorine-containing monomer such as vinyl chloride, dichloroethylene or chloroprene; alkyl group having hydroxyl group such as hydroxyethyl vinyl ether or hydroxypropyl vinyl ether Vinyl ether; ethylene glycol monoallyl ether, propylene glycol monoallyl ether diethylene glycol monoallyl ether and other alkanediol monoallyl ether; ethylene, propylene, isobutylene and other α-olefin; vinyl acetate a vinyl ester such as ester, vinyl propionate, vinyl butyrate or trimethyl vinyl acetate; a vinyl ether such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether or cyclohexyl vinyl ether; An allyl ether such as ethyl allyl ether or butyl allyl ether.

. Synthetic method The emulsion of the acrylic resin can be obtained, for example, by an emulsion polymerization method. There is no particular limitation on the method of the emulsion polymerization, and the various monomers, chain transfer agents, surfactants, radical polymerization initiators, and the like may be used in an aqueous medium by a conventionally known method. In the dispersion system in which the other additive component is a basic component, the monomer is polymerized to produce an emulsion.

○ Other Resin The above-mentioned binder resin may further contain a polyamide resin or a polyester resin.

. Polyamine resin The aforementioned polyamide resin has a guanamine bond in the main chain, and can be obtained, for example, by a dehydration condensation reaction of a dicarboxylic acid and a diamine. For example, the aforementioned dicarboxylic acid may, for example, be adipic acid, sebacic acid, sebacic acid, pimelic acid, suberic acid, decane dicarboxylic acid, fumaric acid, oleic acid or linoleic acid, etc. Dimer acid dimerized by unsaturated fatty acids, and the like. These dicarboxylic acids may be used singly or in combination of two or more. For example, the aforementioned diamine may, for example, be ethylenediamine, hexamethylenediamine, butanediamine, pentanediamine, m-xylenediamine, phenylenediamine, diethylenetriamine, piperazine or the like. These diamines may be used singly or in combination of two or more.

. Polyester Resin The above polyester resin can be produced, for example, by the following known methods: (1) a method of polycondensing a predetermined acid with an alcohol; (2) a polycondensation of a predetermined acid with an alcohol and then depolymerized by a polybasic acid. Method; or (3) a method of adding a predetermined acid to a polycondensation of an alcohol, and then adding an acid anhydride.

The acid constituting the polyester resin may be at least a polybasic acid, and a monocarboxylic acid may be used in combination as needed. For example, the polybasic acid may, for example, be an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an alicyclic dicarboxylic acid. Specific examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, naphthalene dicarboxylic acid, and diphenyl phthalic acid. For example, specific examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, and cerium. a saturated aliphatic dicarboxylic acid such as an acid, dodecanedioic acid or a hydrogenated dimer acid; and fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, and An unsaturated aliphatic dicarboxylic acid such as a polymer acid. Specific examples of the alicyclic dicarboxylic acid include, for example, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5. - norbornene dicarboxylic acid, 2,5-nordecene dicarboxylic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride or the like. Further, a small amount of sodium 5-sulfoisophthalate or 5-hydroxyisophthalic acid may be used as the polybasic acid. A trifunctional or higher polybasic acid can also be used, and, for example, trimellitic acid, pyroghuric acid, diphenyl ketone tetracarboxylic acid, trimellitic anhydride, pyrogallic anhydride, diphenyl ketone tetracarboxylic anhydride, Trimellitic acid, ethylene glycol bis(hydrogen trimellitate), glycerol ginseng (dehydrated trimellitate), 1,2,3,4-butanetetracarboxylic acid, and the like.

For example, specific examples of the aforementioned monocarboxylic acid include, for example, fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and linoleic acid, benzoic acid, and p-tert- Butylbenzoic acid, cyclohexane acid, 4-hydroxyphenyl stearic acid, and the like.

The alcohol constituting the polyester resin may be at least a polyhydric alcohol, and a monohydric alcohol may be used in combination as needed.

For example, the above polyol may, for example, be an aliphatic diol, an alicyclic diol, an ether bond-containing diol or the like. For example, specific examples of the aliphatic diol include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, and 2-methyl-1,3-propanediol. 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butyl Propylene glycol and the like. Specific examples of the alicyclic diol include, for example, 1,4-cyclohexanedimethanol. Specific examples of the ether-containing diol include, for example, diethylene glycol, triethylene glycol, dipropylene glycol, and bisphenol such as 2,2-bis[4-(hydroxyethoxy)phenyl]propane. Ethylene oxide adducts of the class (bisphenol A); ethylene oxide adducts of bisphenols (bisphenol S) such as bis[4-(hydroxyethoxy)phenyl]anthracene; polyethylene glycol, Polypropylene glycol, polybutane diol and the like. A trifunctional or higher polyhydric alcohol can also be used, and examples thereof include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

For example, specific examples of the monohydric alcohol include stearyl alcohol, 2-phenoxyethanol, and the like.

In order to make the polyester resin soluble in water, it is preferred to neutralize part or all of the carboxyl group in the resin by a basic compound. The basic compound may be, for example, the same basic compound as the basic compound exemplified in the above ". Neutralizer".

In the present embodiment, the binder resin preferably contains 70% or less of the resin other than the urethane resin, and more preferably 50% or less, more preferably 30% or less, and particularly preferably contains the resin. 10% or less. When the amount of the resin other than the urethane-based resin contained in the binder resin is within the above range, since the urethane-based resin is sufficiently contained, foaming of the thermoplastic resin is not inhibited, and the resin can be obtained. A sheet of raw material that smoothes the printed surface.

In the present embodiment, the content of the binder resin is preferably 15% by mass or more and 25% by weight or less based on the total mass of the aqueous ink. When the content of the binder resin is at least the above lower limit value, an appropriate ink viscosity can be obtained, and if it is at most the above upper limit value, ink flowability can be prevented from being lowered, and work efficiency in ink production and printing can be improved. .

◎ Solvent In the present embodiment, the solvent may be a known compound which can be usually used as a solvent for aqueous ink. For example, water, alcoholic solvents such as methanol, ethanol, isopropanol, n-propanol, and n-butanol are exemplified, and are not limited thereto. These solvents may be contained alone or in a mixture of two or more kinds.

(Foaming Inhibiting Ink) The foaming suppressing ink used in the printing layer of the present embodiment is a solvent added to the structure of the foaming suppressing ink coating portion in a dry state. That is, the foaming suppressing ink contains a binder resin and a solvent. Further, the foaming suppressing ink may contain various additives for inks such as an auxiliary agent, a pigment dispersing agent, a leveling agent, a surfactant, and an antifoaming agent, as needed. Further, the foaming suppressing ink may contain a coloring agent or may not contain a coloring agent. In order to easily see the unevenness in appearance, it is desirable that the color of the foamed portion and the foaming suppressing portion are not greatly different. Therefore, it is preferable that the foaming suppressing ink does not contain a coloring agent, or contains a coloring agent in the solid content of the ink. 30% by weight or less is preferably 20% by weight or less, and more preferably 10% by weight or less. Accordingly, the foaming suppression ink coating portion 1c can be colored or colorless. When it is colorless or light, it is easy to see the unevenness of the general foaming portion 4, the first printing foam portion 5a, the second printing foam portion 5b, and the foaming suppression ink coating portion 1c. of. Further, even if it is colored, it is preferable because it is light blue or green which is a cool color, since the unevenness is easily emphasized and is easily seen.

Examples of the coloring agent, the auxiliary agent, and the solvent include a coloring agent, an auxiliary agent, and a solvent which are the same as the coloring agent, the auxiliary agent, and the solvent exemplified above (aqueous ink).

The binder resin contains a resin having a glass transition point of 60° C. or more and 120° C. or less, and preferably 70% by mass or more of the resin solid content of the resin resin, and preferably 80% by mass or more. More preferably, it is contained in an amount of 90% by mass or more. When the glass transition point is 70% by mass or more of the resin in the above range, a high foaming suppressing effect can be obtained. That is, the content of the resin, the colorant, and the auxiliary agent having a glass transition point of less than 30 ° C or more than 120 ° C in the foaming-inhibiting ink coating portion 1c is preferably less than 30% by mass, preferably less than 20% by mass, more preferably It is less than 10% by mass.

Further, the glass transition point of the resin is preferably 60 ° C or more and 120 ° C or less. By using a foaming suppressing ink containing a resin having a glass transition point within the above range, even in an aqueous flexographic printing method in which the amount of ink applied is small, foaming can be sufficiently suppressed by one printing, and by controlling Concavities and convexities give the printed surface excellent design. For example, the resin having a glass transition point of 60 ° C or more and 120 ° C or less may be, for example, an acrylic resin or a polyester resin, and is not limited thereto.

The acrylic resin can be suitably selected from the acrylic monomers exemplified in the above "○ acrylic resin" and other monomers copolymerizable with the acrylic monomer so that the glass transition point is 60 ° C or higher. Further, it was synthesized by polymerization at 120 ° C or lower. In addition, as the polyester resin, various acids and various alcohols exemplified in the above "polyester resin" can be used, for example, in a synthesis method in which various acids and various alcohols are polycondensed and polymerized by various polybasic acids, suitably The type of the acid and the alcohol are selected such that the glass transition point constitutes 60 ° C or more and 120 ° C or less, and is synthesized by controlling the ratio of depolymerization.

Among them, the resin having a glass transition point of 60 ° C or more and 120 ° C or less is preferably an acrylic resin.

[Foaming Thermoplastic Resin Layer] In the raw material sheet of the present embodiment, the foamed layer is obtained by heating a thermoplastic resin layer. That is, the foamed layer is a foamed thermoplastic resin layer (foamed thermoplastic resin layer). The thermoplastic resin to be used in the foamed thermoplastic resin layer is not particularly limited as long as it can be laminated and foamable, and any thermoplastic resin such as a crystalline resin or an amorphous resin can be used. . For example, examples of the crystalline resin include polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyester resins, polyamines, polyacetals, and PPS resins. For example, examples of the amorphous resin include polystyrene, polyvinyl chloride, ABS resin, acrylic resin, denatured PPE, polycarbonate, polyurethane, polyvinyl acetate, and amorphous polyethylene terephthalate. Ester (PET) and the like. The thermoplastic resin preferably has a melting point of 80 to 120 °C. Further, the thermoplastic resin may be a single resin in a single layer or a plurality of resins may be used in a plurality of layers. However, from the viewpoint of foamability, it is preferably a single layer.

Among them, the thermoplastic resin used in the foamed thermoplastic resin layer is preferably polyethylene because it has excellent build-up suitability and foamability. Polyethylene can be roughly classified into linear low density polyethylene, low density polyethylene, medium density polyethylene, and high density polyethylene. In terms of density, the linear low-density polyethylene is 888 to 910 kg/m ³ , the low-density polyethylene is 910 kg/m ³ or more and 925 kg/m ³ or less, and the medium-density polyethylene is 925 kg/m ³ or more and 940 kg/ Further, m ³ or less, further, the high-density polyethylene is 940 kg/m ³ or more and 970 kg/m ³ or less. In terms of melting point, the linear low-density polyethylene is 55° C. or higher and 120° C. or lower, the low-density polyethylene is 105° C. or higher and 120° C. or lower, and the medium-density polyethylene is 120° C. or higher and 125° C. or lower. The high density polyethylene is 125 ° C or more and 135 ° C or less.

The thickness of the foamed layer (foamed thermoplastic resin layer) is not particularly limited as long as it is sufficient to impart at least one of desired heat insulating properties and design properties, and is, for example, generally The bubble portion, the first printing foam portion, and the second printing foam portion may be 0.01 mm or more and 4 mm or less, and may be 0 mm or more and 1 mm or less in the foam suppressing portion.

[Non-foamed thermoplastic resin layer] In the raw material sheet of the present embodiment, in order to improve the foaming efficiency, it is preferable to use a thermoplastic resin having a melting point higher than that of the foamed thermoplastic resin layer, and the heat treatment is not performed at the same time. The foamed thermoplastic resin layer (non-foamed thermoplastic resin layer) or aluminum foil or the like covers the opposite wall side of the wall surface of the trunk member having the foamed thermoplastic resin layer. When the single side of the paper substrate is maintained in a base state (in a state where it is not covered by the coating layer or the coating layer), moisture in the paper is evaporated from the uncovered surface to the atmosphere during the heat treatment, and it is difficult to sufficiently and reliably foam. Therefore, by providing such a cover layer, the moisture in the paper can be effectively assisted in foaming. When the raw material sheet is used as the foaming paper container, if the non-foamed thermoplastic resin layer or the aluminum foil or the like is present on the inner wall surface side of the trunk member, it is possible to prevent the filling liquid or the like from penetrating into the paper. ideal.

The thermoplastic resin used in the non-foamed thermoplastic resin layer of the raw material sheet of the present embodiment may be the same as or different from the foamed thermoplastic resin layer. In the same case, a difference in melting point can be caused by making the difference in density. For example, when polyethylene is selected as the thermoplastic resin of both, the foamed thermoplastic resin layer is made of low density polyethylene, and the non-foamed thermoplastic resin layer is made of medium density or high density polyethylene. The difference in melting point between the foamed thermoplastic resin layer and the non-foamed thermoplastic resin layer in the thermoplastic resin is preferably 5° C. or more, and the melting point of the thermoplastic resin of the non-foamed thermoplastic resin layer is not dissolved as long as it is heated. The diffusion of the evaporated water is not particularly limited, but it is preferably 125 ° C or more.

[Paper base material] For example, the paper base material used in the raw material sheet of the present embodiment may be, for example, a chemical pulp obtained from wood and mechanical pulp as a main body, and marijuana may be blended therein as needed. The non-wood pulp such as bamboo is used, and the paper substrate obtained by papermaking by a general papermaking step is not limited thereto. Among them, the paper base material used in the raw material sheet of the present embodiment preferably contains chemical pulp. By containing chemical pulp, the density can be easily increased compared to the case of using mechanical pulp, and yellowing can be suppressed when stored for a long period of time or at a high temperature for a long time, and further, the strength of the container is assumed, The rigidity will increase. The blending ratio of the chemical pulp used in the paper base material to the total raw material pulp is preferably 80% by weight or more, more preferably 90% by weight or more, and still more preferably 95% by weight or more. Further, since the chemical pulp contains a large amount of fibers derived from conifers, the foaming property is high, which is preferable. The blending ratio of the chemical pulp derived from the coniferous tree to the total raw material pulp used in the paper base material is preferably 5% or more, more preferably 10% or more, and still more preferably 20% or more.

The basis weight of the base paper of the paper substrate may be, for example, 25 g/m ² or more and 500 g/m ² or less. In addition, when the raw material sheet of the present embodiment is used for a container, the basis weight of the paper base material may be, for example, 30 g/m ² or more and 400 g/m ² or less in consideration of foaming property. By setting the basis weight of the base paper of the raw material sheet of the present embodiment to the above lower limit value, it is possible to sufficiently secure the moisture content necessary for imparting heat insulating properties and design properties by foaming. Further, by setting the basis weight of the base paper of the raw material sheet of the present embodiment to be equal to or less than the above upper limit value, the processing can be easily performed after foaming, and the cost of the paper base material can be suppressed within a suitable range.

The degree of filtration of the pulp used in the paper substrate ("Canadian Standard" freeness; CSF) is preferably 150 mL or more and 600 mL or less, more preferably 200 mL or more and 580 mL or less. When the CSF of the pulp is 600 mL or less, the water vapor does not easily pass through the inside of the paper substrate, and the water vapor is less likely to be detached from the end surface of the paper substrate, so that the foaming thickness is increased. When the CSF of the pulp is 200 mL or more, the power consumption for lowering the degree of filtration without beating is not increased, and it is excellent on the cost side. Moreover, the equipment for enhancing the beating ability can be alleviated.

The density of the paper substrate is preferably 0.6 g/cm ³ or more, more preferably 0.7 g/cm ³ or more, and still more preferably 0.8 g/cm ³ or more. The thickness of the paper substrate may be, for example, 20 μm or more and 500 μm or less.

As a method of producing a paper substrate, a paper material prepared by adding the above-mentioned pulp, water, and, if necessary, a filler or other medicine, is sprayed onto a wire of a paper machine, and is dehydrated in the wire portion and water is pressed in the press section. After drying in the drying section, if necessary, a size press to impart strength or water repellency to the paper, or a calendering process to adjust the unevenness of the surface of the paper to perform papermaking, wind the finished paper, and finish it into a predetermined winding size. carry out. Further, in order to impart paper strength or water repellency to the paper, two or more kinds of drugs such as polyvinyl alcohol (PVA), starch, and a surface sizing agent may be used alone or in combination. Further, the production of the paper substrate in the present embodiment is not limited thereto.

<Manufacturing Method of Raw Material Sheet> In one embodiment, the present invention provides a method for producing a raw material sheet for a foamable paper product, comprising the steps of: forming a thermoplastic resin layer on a paper base a thermoplastic resin layer formed on at least one side of the material; and an aqueous ink coating portion forming step of coating the surface of the paper substrate on which the thermoplastic resin layer has been formed on the surface of the paper substrate after the thermoplastic resin layer forming step a water-based ink which is dried to form an aqueous ink coating portion, and a foaming step of foaming the thermoplastic resin layer after the aqueous ink-coating portion forming step, and forming a general foaming portion and A foam layer composed of a foamed portion is printed.

According to the production method of the present embodiment, a raw material sheet having a smooth printing surface and excellent heat insulating properties can be obtained. Hereinafter, each step will be described in detail.

[The Step of Forming Thermoplastic Resin Layer] First, a thermoplastic resin layer is formed on at least one side of the paper substrate. The method of forming the thermoplastic resin layer is not particularly limited. For example, it can be laminated by a method such as extrusion lamination, wet lamination, or dry lamination, which is bonded to a film which has been previously formed into a film. Among them, the method of forming the thermoplastic resin layer is preferably an extrusion lamination method from the viewpoints of adhesion to a paper substrate, foaming property, and the like. For example, the laminate is a method in which a thermoplastic resin layer is extruded from a T-shape in a state of a molten resin film on a surface on which a foaming accelerator has been coated on a paper substrate, and is pressed against a cooling roll and a pressure thereof. The rolls are cooled and crimped. In the extrusion laminate, the operating conditions such as the melting temperature and the lamination speed of the resin can be appropriately set depending on the type of resin or the device to be used, and are not particularly limited. Generally, the melting temperature is 200° C. or higher and 350° C. or lower. The lamination speed is 50 m/min or more and 200 m/min or less. Further, the nip roll is a nip roll using a hardness of 70 degrees or more (JIS K-6253), and the line pressure is preferably pressed and pressure-bonded by 15 kgf/cm or more.

If necessary, in order to improve the adhesion of the paper substrate or the thermoplastic resin, corona treatment, ozone treatment, or the like may be performed.

The thickness of the thermoplastic resin layer (the foamed thermoplastic resin layer before heating) may be a thickness sufficient to impart a desired heat insulating property when a foamed layer (foamed thermoplastic resin layer) is formed after heating, and There is no particular limitation, and for example, it may be 20 μm or more and 90 μm or less.

In addition, the thickness of the non-foamed thermoplastic resin layer before heating may be a thickness sufficient to prevent scattering of evaporated water, and is, for example, 20 μm or more and 50 μm or less.

[Aqueous Ink Coating Portion Forming Step] Next, an aqueous ink is applied onto the formed thermoplastic resin layer to form an aqueous ink coating portion. As the aqueous ink, the same aqueous ink as the aqueous ink exemplified above (aqueous ink) can be used. The method of applying the aqueous ink to the thermoplastic resin layer is not particularly limited, and examples thereof include a water-based gravure printing method, a water-based flexographic printing method, and a screen printing method. Among them, the method of applying the aqueous ink to the paper substrate is preferably an aqueous flexographic printing method which can be applied by a low coating amount. Further, the aqueous ink used in the present embodiment can be colored in the same manner as the aqueous gravure printing method even in a low-coating aqueous flexographic printing method, and a clear printing can be obtained.

[Foaming Step] Next, the thermoplastic resin layer is subjected to heat treatment, and the thermoplastic resin layer is foamed to form a foamed layer composed of a general foamed portion and a printed foamed portion.

The heating temperature and the heating time vary depending on the type of the paper base material and the thermoplastic resin to be used, and the most suitable combination of the heating temperature and the heating time for the thermoplastic resin to be used can be appropriately determined. However, the heating temperature is suitably a little a temperature higher than the melting point of the foamed thermoplastic resin (melting point + 5 ° C or more and 30 ° C or less), generally, the heating temperature is 110 ° C or more and 200 ° C or less, and the heating time is 1 minute or more and 6 minutes or less. . There is no particular limitation on the heating method. For example, any method such as hot air, electric heat, or electron beam can be used. In the passage provided with the conveying mechanism using the conveyor belt, if heated by hot air or electric heating, it can be mass-produced at low cost.

[Foaming Inhibition Ink Coating Portion Forming Step] In the manufacturing method of the present embodiment, after the aqueous ink coating portion forming step and before the foaming step, a foaming suppressing ink coating portion forming step may be provided. After the solvent of the aqueous ink is dried and the aqueous ink coating portion is formed, the foaming suppressing ink is applied to form a foaming-inhibiting ink coating portion. As the foaming suppressing ink, the same foaming suppressing ink as the foaming suppressing ink exemplified above (foaming suppressing ink) can be used. The method of applying the foaming suppressing ink to the thermoplastic resin layer is not particularly limited, and examples thereof include a water-based gravure printing method, an aqueous flexographic printing method, and a screen printing method. Among them, the method of applying the foaming inhibiting ink to the paper substrate is preferably an aqueous flexographic printing method which can be applied by a low coating amount.

As exemplified in <Application> described later, the obtained raw material sheet can be further processed by a known method to form a desired form.

<Application> The raw material sheet of the present embodiment is used in a paper product having a heat insulating property and a smooth printing surface, and specifically, for example, it can be used for a foaming paper cup, a foaming paper container, a specification, and a pattern. Paper, wrapping paper, wallpaper, etc.

[Expandable Paper Container] In one embodiment, the present invention provides a foamable paper container composed of the above-mentioned raw material sheet.

The foamable paper container of the present embodiment has a smooth printing surface, and heat is not easily transmitted to the hand, and has excellent heat insulating properties in practical use.

The foamable paper container of the present embodiment can be produced, for example, by the following method. First, a raw material sheet is spun from a winding roller. Next, the blank for the trunk member and the blank for the bottom plate member are pierced from the raw material sheet, and assembled into a container shape by a conventional cup forming machine. Here, the foamed thermoplastic resin layer may be present on either or both sides of the outer wall surface side and the inner wall surface side of the trunk member, and may be appropriately determined depending on the heat insulating property, the hand feeling, the aesthetic appearance, etc., however, When the foamed surface is formed inside the container, the foamed resin is damaged by the chopsticks, the fork, or the like during the eating and the like, and is likely to be present on the outer wall surface side. Therefore, for example, the trunk member is assembled such that the foamed thermoplastic resin layer faces the outside of the container, and the non-foamed thermoplastic resin layer faces the inside of the container. As the bottom plate member, a bottom plate member in which an unfoamed thermoplastic resin layer is provided on at least one side of the inner surface side of the container of the paper substrate is preferably used. This is to prevent liquids and the like from penetrating into the paper. The thermoplastic resin to be used for the bottom plate member may be the same as or different from the trunk member, and the method of laminating may be a method of bonding to a film which has been previously formed into a film, such as a wet laminate method or a dry laminate method, in addition to the laminate method.

In order to prevent the heat release from the bottom surface of the container after the hot water is poured into the cup surface or the like, it is effective to provide the foamed thermoplastic resin layer to the bottom member. Especially ideal for outdoor use, winter or cold. Further, as the cover material, a cover material which also has a foamed thermoplastic resin layer can be used.

EXAMPLES Hereinafter, the present invention will be described in further detail by way of examples, however, the present invention is not limited to the examples.

[Example 1] A laminated low-density polyethylene was extruded at a thickness of 70 μm on one side of a paper substrate of 300 g/m ² (thickness 330 μm, density 0.91 g/cm ³ , chemical pulp 100%, moisture content 7.8%). Japanese Polyethylene Co., Ltd. trade name: LC701, density 0.918g/cm ³ , melting point 106 ° C). On the opposite side of the paper substrate, a laminated medium density polyethylene (trade name: LW04, manufactured by Tosoh Corporation, density: 0.940 g/cm ³ , melting point: 131 ° C) was placed at a thickness of 40 μm. The aqueous ink A was used on the surface of the low-density polyethylene laminated film (the content of the solid component was 60% by mass of the urethane-based resin (glass transition point: 10 ° C), and 40% by mass of the colorant. Dispersion in a solvent (ethanol) : In the state of water = 10:90), the total content of the resin and the coloring agent is 40% by mass.) For each color, a flexo proofing machine (Flexo proof) 100 is used according to each printing pattern shown in Table 1. Industrial company system) performs flexographic printing. After printing, it was placed in an oven and heated by 120 ° C for 120 seconds. Table 1 shows the foaming thickness of each ink coating portion. Further, in Tables 3 and 5, the foaming inhibition ratio of each ink coating portion was summarized.

[Example 2] On a single side of a paper substrate of 300 g/m ² (thickness 330 μm, density 0.91 g/cm ³ , chemical pulp 100%, moisture content 7.8%), the laminated low-density polyethylene was extruded at a thickness of 70 μm. Density polyethylene (trade name: LC701, density: 0.918 g/cm ³ , melting point: 106 ° C, manufactured by Nippon Polyethylene Co., Ltd.). On the opposite side of the paper substrate, a laminated medium density polyethylene (trade name: LW04, manufactured by Tosoh Corporation, density: 0.940 g/cm ³ , melting point: 131 ° C) was placed at a thickness of 40 μm. The aqueous ink B was used on the surface of the low-density polyethylene laminated film (the content of the solid component was 60% by mass of the urethane-based resin (glass transition point: 10 ° C), and 40% by mass of the colorant. Dispersed in a solvent (ethanol) The total content of the resin and the coloring agent in the state of water = 20:80) was 40% by mass.) For each color of each of the printing patterns shown in Table 1, a printing tester (Gravure auto proofing machine (Gravure auto) was used. Proofer), manufactured by Matsuo Industries Co., Ltd.). After printing, it was placed in an oven and heated by 120 ° C for 120 seconds. Table 1 shows the foaming thickness of each ink coating portion. Further, in Tables 3 and 5, the foaming inhibition ratio of each ink coating portion was summarized.

[Example 3] On one side of a paper substrate of 260 g/m ² (thickness: 280 μm, density: 0.93 g/cm ³ , chemical pulp 100%, water content: 7.6%), the laminated low-density polyethylene was extruded at a thickness of 70 μm. Density polyethylene (trade name: LC701, density: 0.918 g/cm ³ , melting point: 106 ° C, manufactured by Nippon Polyethylene Co., Ltd.). On the opposite side of the paper substrate, a laminated medium density polyethylene (trade name: LW04, manufactured by Tosoh Corporation, density: 0.940 g/cm ³ , melting point: 131 ° C) was placed at a thickness of 40 μm. The aqueous ink A was used on the surface of the low-density polyethylene laminated film (the content of the solid component was 60% by mass of the urethane-based resin (glass transition point: 10 ° C), and 40% by mass of the colorant. Dispersion in a solvent (ethanol) In the state of water: 10:90), the total content of the resin and the coloring agent is 40% by mass.), and the foaming-inhibiting ink F (acrylic resin (glass transition point: 90 ° C): 20% by mass, solvent) (Ethanol: water = 10:90) 80% by mass), according to each of the printing patterns shown in Table 1, flexographic printing was performed using a printing machine. After printing, it was placed in an oven and heated by 120 ° C for 120 seconds. Table 1 shows the foaming thickness of each ink coating portion. Further, in Tables 3 and 6, the foaming inhibition ratio of each ink coating portion was summarized.

[Example 4] A laminated low-density polyethylene was extruded at a thickness of 15 μm on one side of a paper substrate of 135 g/m ² (thickness: 201 μm, density: 0.67 g/cm ³ , chemical pulp 100%, moisture content: 7.0%). Japanese Polyethylene Co., Ltd. trade name: LC701, density 0.918g/cm ³ , melting point 106 ° C). On the opposite side of the paper substrate, a laminated medium density polyethylene (trade name: LW04, manufactured by Tosoh Corporation, density: 0.940 g/cm ³ , melting point: 131 ° C) was placed at a thickness of 45 μm. The aqueous ink A was used on the surface of the low-density polyethylene laminated film (the content of the solid component was 60% by mass of the urethane-based resin (glass transition point: 10 ° C), and 40% by mass of the colorant. Dispersion in a solvent (ethanol) In the state of water: 10:90), the total content of the resin and the coloring agent is 40% by mass.), and the foaming-inhibiting ink F (acrylic resin (glass transition point: 90 ° C): 20% by mass, solvent) (Ethanol: water = 10:90) 80% by mass), according to each of the printing patterns shown in Table 1, flexographic printing was performed using a printing machine. After printing, it was placed in an oven and heated by 130 ° C for 180 seconds. Table 1 shows the foaming thickness of each ink coating portion. Further, in Tables 3 and 6, the foaming inhibition ratio of each ink coating portion was summarized.

[Table 1]

[Comparative Example 1] Laminated low-density polyethylene was extruded at a thickness of 70 μm on one side of a paper substrate of 300 g/m ² (thickness: 330 μm, density: 0.91 g/cm ³ , chemical pulp 100%, moisture content: 7.8%). Japanese Polyethylene Co., Ltd. trade name: LC701, density 0.918g/cm ³ , melting point 106 ° C). On the opposite side of the paper substrate, a laminated medium density polyethylene (trade name: LW04, manufactured by Tosoh Corporation, density: 0.940 g/cm ³ , melting point: 131 ° C) was placed at a thickness of 40 μm. The aqueous ink C was used on the surface of the low-density polyethylene laminated film (the content of the solid component was 60% by mass of the acrylic resin and 40% by mass of the colorant), and it was dispersed in a solvent (ethanol: water = 5:95). The total content of the resin and the coloring agent is 40% by mass.), and the foaming-inhibiting ink G (acrylic resin (glass transition point: 45 ° C) 20% by mass, solvent (ethanol: water = 10:90) 80 According to each of the printing patterns shown in Table 2, flexographic printing was performed using a Flexo proof 100 (manufactured by Matsuo Sangyo Co., Ltd.). After printing, it was placed in an oven and heated by 120 ° C for 120 seconds. Table 2 shows the foaming thickness of each ink coating portion. Moreover, the foaming suppression ratio of each ink coating part was summarized in Tables 4, 5, and 6.

[Comparative Example 2] Laminated low-density polyethylene was extruded at a thickness of 70 μm on one side of a paper substrate of 300 g/m ² (thickness: 330 μm, density: 0.91 g/cm ³ , chemical pulp 100%, moisture content: 7.8%). Japanese Polyethylene Co., Ltd. trade name: LC701, density 0.918g/cm ³ , melting point 106 ° C). On the opposite side of the paper substrate, a laminated medium density polyethylene (trade name: LW04, manufactured by Tosoh Corporation, density: 0.940 g/cm ³ , melting point: 131 ° C) was placed at a thickness of 40 μm. An oil-based ink D was used on the surface of the low-density polyethylene laminated film (the content of the solid component was 30% by mass of the urethane-based resin, 20% by mass of the nitrocellulose, and 50% by mass of the colorant. The resin in the ink state) The content is 10% by mass, and is dispersed in a solvent (a mixed solvent composed of isopropyl alcohol (10%) / ethyl acetate (40%) / toluene (30%) / methyl ethyl ketone (20%)) In the state in which the total content of the resin, nitrocellulose, and coloring agent is 20% by mass.), according to each printing pattern shown in Table 2, a printing tester (Gravure auto proofer), Matsuo Gravure printing is carried out by an industrial company. After printing, it was placed in an oven and heated by 120 ° C for 120 seconds. Table 2 shows the foaming thickness of each ink coating portion. Further, in Table 4, the foaming inhibition ratio of each ink coating portion was summarized.

[Table 2]

[table 3]

[Table 4]

[table 5]

[Table 6]

According to Table 3, in Example 1, Example 2, Example 3, and Example 4, the foaming inhibition ratio (1) was 19.0%, 38.3%, 21.1%, and 26.3%, respectively, and the composition was 40% or less. Here, according to Table 4, Comparative Examples 1 and 2 were 43.8% and 49.9%, and were higher than 40%. Further, according to Table 3, in Example 1, Example 2, and Example 3, the foaming inhibition ratio (2) was 26.0%, 46.7%, and 34.9%, respectively, and the composition was 50% or less. Table 4, Comparative Examples 1 and 2, were 61.1% and 62.0%, and were higher than 50%.

Further, according to Table 5, in Example 1 and Example 3 in which aqueous flexographic printing was carried out, the foaming inhibition ratio (3) was 10.3% and 17.5%, respectively, and the composition was 20% or less. Comparative Example 1 for flexographic printing was 36.8% and higher than 20%.

Further, according to Table 6, in Example 3 and Example 4 in which the foaming suppressing ink F was applied, the foaming inhibition ratio was 45.9%, 44.8%, and 52.9%, and the composition was 40% or more. Comparative Example 1 of the foaming suppressing ink G was 36.9% and 30.3%, and was less than 40%. From this, it is understood that even in the flexographic printing which is a low coating amount, a sufficient foaming suppressing effect can be obtained by using the foaming suppressing ink F.

From the above, it was confirmed that by using an aqueous ink containing an urethane-based resin, the foaming inhibition ratio calculated from the following can be suppressed to 40% or less: relative to the foamed layer when the aqueous ink is not applied The foaming thickness of the aqueous ink coating portion of the foaming thickness; in addition, the foaming inhibition rate calculated from the following can be suppressed to 20% or less: two layers of the foaming thickness of the aqueous ink coating portion The foaming thickness of the aqueous ink coating portion; and a foamed paper product having a smooth surface of the low-density polyethylene film can be obtained. Further, it was confirmed that even in the case of flexographic printing which is a low coating amount, printing of a low-density polyethylene film can be obtained by using a foaming suppressing ink containing a resin having a glass transition point of 60 ° C or more and 120 ° C or less. The surface is formed with irregularities and imparts excellent design properties to the foamed paper product.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a raw material sheet having a foaming paper container composed of the above-mentioned raw material sheet, and the raw material sheet containing an ink having a small influence on the environment, and a printing layer can be obtained. A foaming paper product having a smooth surface and excellent appearance.

A‧‧‧Water-based ink non-painting area

B‧‧‧Water-based ink coating area

Foaming thickness of X‧‧‧ water-based ink non-coating part (general foaming part 4)

Y‧‧‧ foaming thickness of a layer of aqueous ink coating

Foaming thickness of Y’‧‧‧ two-layer aqueous ink coating

Z‧‧‧Foaming Inhibition Foam Thickness of Ink Coating Section

1‧‧‧Printing layer

1a‧‧‧1st water-based ink coating department

1b‧‧‧2nd water-based ink coating department

1c‧‧‧Foaming Inhibition Coating Department

2a‧‧‧Non-foamed thermoplastic resin layer

2b‧‧‧Foaming thermoplastic resin layer

2b'‧‧‧Foam layer (foamed thermoplastic resin layer after heating)

3‧‧‧paper substrate

4‧‧‧General foaming department

5‧‧‧Printing Foam Department

5a‧‧‧1st printing foaming department

5b‧‧‧2nd printing foaming department

5c‧‧‧Foam suppression department

10, 30‧‧‧ Raw material sheets before foaming

20, 40‧‧‧Filled raw material sheet

Fig. 1A is a cross-sectional view schematically showing an embodiment of a raw material sheet (before foaming) of the present invention. Fig. 1B is a cross-sectional view schematically showing an embodiment of a raw material sheet (after foaming) of the present invention. Fig. 2A is a cross-sectional view schematically showing another embodiment of the raw material sheet of the present invention (before foaming). Fig. 2B is a cross-sectional view schematically showing another embodiment of the raw material sheet of the present invention (after foaming).

Claims (8)

A raw material sheet for a foaming paper product, characterized in that it consists of a paper substrate having a foamed layer which has thermoplasticity of at least one layer of aqueous ink coating on at least one side When the resin layer is heated, and the foaming thickness of the foamed layer when the aqueous ink is not applied is X, and the foaming thickness of the aqueous ink coating portion is Y, the following formula [1] The foaming inhibition rate is 40% or less: [Formula 1] The foaming inhibition ratio (%) = (1-Y/X) × 100 [1]. The raw material sheet of claim 1, wherein the aqueous ink contains a colorant and a binder resin, and the resin solid content of the binder resin contains an urethane system having a glass transition point of -20 ° C or more and 30 ° C or less. The resin is 30% by mass or more. The raw material sheet of claim 1 or 2, wherein the aqueous ink further contains an extender pigment. The raw material sheet of claim 3, wherein the aforementioned extender pigment is cerium oxide. The raw material sheet according to any one of claims 1 to 4, wherein the foamed layer further comprises a foaming suppressing portion. The raw material sheet of claim 5, wherein the foaming suppressing portion is formed by heating a thermoplastic resin layer having a foaming-inhibiting ink coating portion, and the foaming inhibiting ink contains a glass transition point of 60 ° C or more and 120 The resin is not more than 70 C%, and the resin accounts for 70% by weight or more of the resin solid content of the above-mentioned binder resin. The raw material sheet of claim 6, wherein the resin having a glass transition point of 60 ° C or more and 120 ° C or less is an acrylic resin. A foamable paper container comprising the raw material sheet of any one of claims 1 to 7.