JPWO2018066031A1 - Raw material sheet and foamable paper container used for foamable paper products - Google Patents

Abstract

The present invention provides a raw material sheet from which a foamable paper product having a smooth print layer surface and an excellent appearance can be obtained, containing an ink having little influence on the environment, and a foamable paper container made of the raw material sheet. The present invention is a raw material sheet for use in a foamable paper product, comprising a paper base having a foam layer formed by heating a thermoplastic resin layer having at least one surface of a water-based ink coating portion on one side, When the foamed thickness in the foamed layer when not coated is X and the foamed thickness in the aqueous ink coated portion of one layer is Y, the foaming suppression rate represented by the following formula [1] is 40% or less. The foamable paper container of the present invention comprises the above-mentioned raw material sheet. [Equation 1]

Description

  The present invention relates to a raw material sheet used for foamable paper products and a foamable paper container.

  Generally, foamable paper sheets and foamable paper containers are made by laminating low density polyethylene on one side of base paper and high density or medium density polyethylene on the other side and heating in an oven. The surface of the low density polyethylene has a print layer including a print pattern such as a decorative pattern, a trade name, a company name, and a bar code.

  Examples of the method for forming the printing layer include gravure printing and flexographic printing. In the ink for gravure printing, it is known conventionally that a polyamide resin etc. and a cellulose derivative are included as a binder component. The ink for gravure printing significantly suppresses foaming of low density polyethylene, and in the printed portion and the non-printed portion of the printing layer, or in the printed portion and the overprinting portion further printed on this printed portion. There is a difference in the thickness of low density polyethylene after foaming. As a result, there is a problem that the printed portion or the recoating portion becomes a concave portion, a step is generated, and the printing becomes unclear.

  As an ink for improving the unevenness of the surface of the print layer, Patent Document 1 includes a colorant, a binder resin and a solvent, and the binder resin contains a urethane resin and a vinyl chloride / vinyl acetate copolymer. Based on the total weight of the urethane resin and the vinyl chloride / vinyl acetate copolymer, the mixing ratio of the urethane resin: vinyl chloride / vinyl acetate copolymer is 50:50 to 99: 1, and the elongation of the binder resin The oil-based ink which is 400%-3,000% is disclosed.

Patent No. 4619455 gazette

  According to the oil-based ink described in Patent Document 1, it is possible to obtain a foamable paper product in which the surface of the print layer is smooth and the appearance is excellent, with the unevenness kept as small as possible on the surface of the low density polyethylene after foaming. However, since the oil-based ink uses an organic solvent, there are concerns about environmental and workers' influence. Specifically, there are problems such as residual solvent in printed matter and large amount of solvent (VOC) emissions.

  The present invention has been made in view of the above circumstances, and contains an ink having little influence on the environment, a raw material sheet from which a foamable paper product having a smooth print layer surface and excellent appearance can be obtained, and the raw material sheet Providing a foamable paper container comprising

  As a result of intensive studies to achieve the above object, the present inventors have used an aqueous ink containing a binder resin having a urethane resin in a specific ratio to make the print layer surface smooth and foam excellent in appearance. It has been found that a basic paper product can be obtained, and the present invention has been completed.

［２］前記水性インキが、着色剤、及びバインダー樹脂を含み、前記バインダー樹脂の樹脂固形分中、ガラス転移点が−２０℃以上３０℃以下のウレタン系樹脂を３０質量％以上含有する［１］に記載の原材料シート。
［３］前記水性インキがさらに体質顔料を含む［１］又は［２］に記載の原材料シート。
［４］前記体質顔料が二酸化ケイ素である［３］に記載の原材料シート。
［５］さらに、前記発泡層が発泡抑制部を備える［１］〜［４］のいずれか一つに記載の原材料シート。
［６］前記発泡抑制部は発泡抑制インキ塗装部を有する熱可塑性樹脂層を加熱してなり、
前記発泡抑制インキは、ガラス転移点が６０℃以上１２０℃以下の樹脂を、前記バインダー樹脂の樹脂固形分中、７０重量％以上含有する［５］に記載の原材料シート。
［７］前記ガラス転移点が６０℃以上１２０℃以下の樹脂が、アクリル系樹脂である［６］に記載の原材料シート。
［８］［１］〜［７］のいずれか一つに記載の原材料シートからなることを特徴とする発泡性紙製容器。The present invention includes the following aspects.
[1] A raw material sheet used for foamable paper products,
It consists of a paper base material provided with a foaming layer which heats a thermoplastic resin layer which has one or more water-based ink painting parts on at least one side,
Assuming that the foamed thickness in the foamed layer in the case where the aqueous ink is not applied is X and the foamed thickness in the aqueous ink-coated portion of one layer is Y, the foaming suppression ratio represented by the following formula [1] is 40% or less Raw material sheet characterized by that.

[2] The aqueous ink contains a colorant and a binder resin, and contains 30% by mass or more of a urethane resin having a glass transition temperature of −20 ° C. or more and 30 ° C. or less in the resin solid content of the binder resin ] The raw material sheet as described in.
[3] The raw material sheet according to [1] or [2], wherein the water-based ink further contains an extender pigment.
[4] The raw material sheet according to [3], wherein the extender pigment is silicon dioxide.
[5] The raw material sheet according to any one of [1] to [4], wherein the foam layer further includes a foam suppression portion.
[6] The foam suppression portion is formed by heating a thermoplastic resin layer having a foam suppression ink-coated portion,
The raw material sheet according to [5], wherein the foam suppression ink contains a resin having a glass transition temperature of 60 ° C. or more and 120 ° C. or less in the resin solid content of the binder resin.
[7] The raw material sheet according to [6], wherein the resin having a glass transition temperature of 60 ° C. or more and 120 ° C. or less is an acrylic resin.
[8] A foamable paper container comprising the raw material sheet according to any one of [1] to [7].

  According to the present invention, there is provided a raw material sheet from which a foamable paper product is obtained which contains an ink with little influence on the environment and the printing layer surface is smooth and the appearance is excellent, and a foamable paper container made of the raw material sheet. be able to.

It is a sectional view showing typically one embodiment of a raw material sheet (before foaming) of the present invention. It is a sectional view showing typically one embodiment of a raw material sheet (after foaming) of the present invention. It is sectional drawing which shows typically another embodiment of the raw material sheet (before foaming) of this invention. It is sectional drawing which shows typically another embodiment of the raw material sheet (after foaming) of this invention.

<< Raw Material Sheet >>
In one embodiment, the present invention is a raw material sheet used for foamable paper products, comprising a foam layer formed by heating a thermoplastic resin layer having at least one surface of a water-based ink-coated portion on at least one side. And the foaming thickness in the foaming layer in the case where the aqueous ink is not coated is X, and the foaming thickness in the aqueous ink-coated portion of one layer is Y, the foaming inhibition rate represented by the following formula [1] is 40% Provide the following raw material sheet.

  According to the raw material sheet of the present embodiment, a foamable paper product having a smooth print layer surface and an excellent appearance can be obtained. In addition, since the proportion of alcohol in the solvent is 30% or less and the rest is water without using an organic solvent other than alcohol, the environmental impact is small compared to the conventional oil-based ink. Moreover, even if it is an aqueous | water-based flexographic printing method of a low coating amount, the water-based ink used for the raw material sheet of this embodiment is colored similarly to the water-based gravure printing method, and clear printing is obtained.

<Structure>
1A and 1B are cross-sectional views schematically showing an embodiment of a raw material sheet of the present invention. FIG. 1A shows the raw material sheet before heating and foaming, and FIG. 1B shows the raw material sheet after heating and foaming.
The raw material sheet 10 before foaming of this embodiment has a water-based ink non-coated area A and a water-based ink coated area B which are disposed adjacent to each other in plan view, and has a non-foamed thermoplastic resin layer 2a, a paper base The material 3, the foamed thermoplastic resin layer 2b, and the printing layer 1 (the first water-based ink coated portion 1a and the second water-based ink coated portion 1b) are laminated in this order.
Moreover, in the raw material sheet 20 after foaming of this embodiment, foaming layer 2b 'is foaming thermoplastic resin 2b which has printing layer 1 (1st water-based ink coating part 1a, and 2nd water-based ink coating part 1b) And a normal foam portion 4 present in the water-based ink non-coated area A and a print foam portion 5 present in the water-based ink coated area B. By the application of the water-based ink, the printing foam portion 5 is somewhat suppressed from foaming as compared with the foam portion 4 in general. Furthermore, the printing foam portion 5 is a region where the first water-based ink coated portion is exposed to the surface, that is, the first printing foam portion 5 a formed in one water-based ink coated portion, and the second water-based ink It consists of the area | region where the ink coating part is exposed to the surface, ie, the 2nd printing foam part 5b formed in the two-layer water-based ink coating part.

In the raw material sheet 20 after foaming of this embodiment, when the foaming thickness in the aqueous ink non-painting portion (usually the foaming portion 4) is X and the foaming thickness in the aqueous ink coating portion of the one layer is Y, the following formula [ The foaming suppression ratio represented by 1] is 40% or less, preferably 39% or less, and more preferably 38% or less.
When the foaming suppression rate is in the above range, the boundary between the water-based ink non-coating part and the printing layer becomes a smooth printed matter, and the printing can be clearly viewed.
Moreover, in the raw material sheet 20 after foaming of this embodiment, when a water-based ink coating part is formed by flexographic printing method (namely, the water-based ink application quantity per unit area in a water-based ink coating part is 0.1 g / m ² or more If it is 6.0 g / m ² or less), the foam thickness in the aqueous ink uncoated portion (usually foam section 4) X, when the foaming thickness in the aqueous ink coating portion of the first layer was set to Y, the following equation [ The foaming suppression ratio represented by 1] is 30% or less, preferably 29% or less, and more preferably 28% or less. When the water-based ink coated portion is formed by flexographic printing, the water-based ink coated portion is formed by gravure printing (that is, the amount of water-based ink applied per unit area in the water-based ink coated portion is, for example, 7.0 g / m ^{Since the} amount of use of the ink is smaller than in the case where it is ² or more and 15.0 g / m ² or less, the foaming suppression rate can be further reduced.

As X and Y, an average value of the measurement values of the foam thickness in the water-based ink-coated portion of each layer may be used.
Moreover, although the raw material sheet | seat provided with two-layer water-based ink coating part was illustrated in FIG. 1A and 1B, also about the foam thickness in water-based ink coating parts, such as two or more layers, for example, three layers and four layers, The foam thickness in the water-based ink-coated portion may be measured, and the average value may be used to calculate the antifoaming rate by applying a numerical value to the above-mentioned formula [1].
For example, in FIG. 1B, assuming that the foamed thickness in the two-layer water-based ink-coated portion is Y ′, the foaming suppression ratio may be calculated using Y ′ instead of Y in the above formula [1].

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

Moreover, in the raw material sheet 20 after foaming of this embodiment, when the foaming thickness in the aqueous ink coating part of said 1 layer is Y and the foaming thickness in the aqueous ink coating part of said 2 layer is Y ', the following formula [2 The foaming suppression ratio represented by the formula is 20% or less, preferably 19% or less, and more preferably 18% or less.
By the foam suppression ratio being in the above range, the surface of the print layer is smooth, and the print can be clearly viewed.

  2A and 2B are cross sectional views schematically showing another embodiment of the raw material sheet of the present invention. FIG. 2A shows the raw material sheet before heating and foaming, and FIG. 2B shows the raw material sheet after heating and foaming. In FIGS. 2A and 2B, the same components as those shown in the already described drawings are denoted by the same reference numerals as those in the already explained drawings, 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 foam suppression ink-coated portion 1c is provided. That is, in the raw material sheet 30 before foaming, the non-foamed thermoplastic resin layer 2a, the paper base material has the water-based ink non-coating area A and the water-based ink coating area B disposed adjacent to each other in plan view. 3, foam layer (foamed thermoplastic resin layer) 2b, and printing layer 1 (first water-based ink coated portion 1a, second water-based ink coated portion 1b, and foam suppression ink coated portion 1c) are laminated in this order ing.
Moreover, the raw material sheet 40 after foaming shown here is the same as the raw material sheet 20 after foaming shown to FIG. 1B except the point provided with the foaming suppression part 5c. That is, in the raw material sheet 40 after foaming, the print foam portion 5 is the first print foam formed in the area where the first water-based ink coated portion is exposed on the surface (that is, one water ink-coated portion). The second print foam portion 5b formed in the portion 5a and the area where the second water-based ink coated portion is exposed on the surface (that is, the two-layer water-based ink coated portion) It consists of the foaming suppression part 5c formed in the exposed area | region.

In the raw material sheet 40 after foaming of this embodiment, when the foamed thickness in the aqueous ink-coated portion of the two layers is Y ′ and the foamed thickness in the anti-foaming ink-coated portion is Z, it is represented by the following formula [3] Rate is 40% or more, preferably 50% or more, more preferably 60% or more, and still more preferably 65% or more.
When the foaming suppression rate is in the above range, it is possible to obtain a raw material sheet to which a smooth printed surface and excellent designability due to asperities are imparted.

As the Y 'and Z, an average value of the measurement values of the foam thickness in the second water-based ink coated portion or the foam suppression ink coated portion may be used.
Moreover, although the raw material sheet | seat provided with two-layer water-based ink coating part was illustrated in FIG. 2A and 2B, also about the foam thickness in water-based ink coating parts, such as two or more layers, for example, three layers, four layers, The foam thickness in the water-based ink coating portion or the foam suppression ink coating portion provided thereon is measured, and using the average value thereof, a numerical value may be applied to the above-mentioned formula [3] to calculate the foaming suppression rate.

  The raw material sheet of the present invention is not limited to those shown in FIGS. 1A to 2B, but some of the configurations of those shown in FIGS. 1A to 2B are changed or deleted within the scope not impairing the effects of the present invention. Or, other configurations may be added to those described above.

For example, in the raw material sheet shown to FIG. 1A-FIG. 2B, you may be equipped with two or more layers, for example, three layers and four-layer water-based ink coating part. Among them, it is preferable that the water-based ink coated portion is 2 or more and 8 or less.
Moreover, in the raw material sheet | seat shown to FIG. 1A-FIG. 2B, what coated the water-based ink on the whole single side | surface and was covered with the printing layer, ie, a sheet which does not have a water-based ink non-coating part may be sufficient.
Moreover, in the raw material sheet | seat shown to FIG. 1A-FIG. 2B, you may provide a foaming thermoplastic resin layer on both surfaces.

Moreover, in the raw material sheet | seat shown to FIG. 2A and FIG. 2B, you may equip the 1st water-based ink coating part with the foam suppression ink coating part. In this case, in the raw material sheet, when the foamed thickness in the aqueous ink-coated portion of the first layer is Y and the foamed thickness in the expansion-suppressed ink coated portion is Z, the foaming suppression rate represented by the following formula [4] is It is 40% or more, preferably 50% or more, more preferably 60% or more, and still more preferably 65% or more.
When the foaming suppression rate is in the above range, it is possible to obtain a raw material sheet to which a smooth printed surface and excellent designability due to asperities are imparted.

Moreover, in the raw material sheet | seat shown to FIG. 2A and FIG. 2B, you may each be equipped with a foam suppression ink coating part on a 1st water-based ink coating part and a 2nd water-based ink coating part. The foaming suppression rate at this time may be calculated using the above-mentioned equation [3] and equation [4].
Moreover, in the raw material sheet | seat shown to FIG. 2A and FIG. 2B, you may provide the bubble suppression ink coating part on the water-based ink non-coating part. In this case, in the raw material sheet, assuming that the foamed thickness in the aqueous ink non-coated portion is X and the foamed thickness in the anti-foaming ink coated portion is Z, the foaming suppression rate represented by the following formula [5] is 40% It is the above, 50% or more is preferable, 60% or more is more preferable, and 65% or more is more preferable.

<Material of composition>
The material which comprises the raw material sheet | seat of this embodiment is demonstrated below.

[Print layer]
In the raw material sheet of the present embodiment, the thickness after drying of the water-based ink-coated area before heating is preferably 2 μm or less per layer. By being 2 micrometers or less, a smooth printing surface can be obtained without suppressing foaming.
When the water-based ink coated portion is, for example, two layers, the printed layer after drying is preferably 4 μm or less. For example, when the water-based ink coated portion is, for example, three layers, the printed layer after drying is 6 μm or less Is preferred.
Moreover, in the raw material sheet of the present embodiment, when the expansion suppression ink coating portion is provided, the thickness after drying of the expansion suppression ink coating portion before heating may be, for example, 0.1 μm or more and 2 μm or less. It may be 2 μm or more and 1 μm or less.
In the thickness after drying of the foaming suppression ink coating part before a heating, when it is more than the said lower limit, it has the outstanding foaming inhibitory effect. Moreover, in the thickness after drying of the expansion suppression ink coating part before a heating, by being below the said upper limit, even if it is gravure, it is not necessary to print twice or more, and can suppress the usage-amount of ink. it can. Further, since it is not necessary to use two printing units, it is possible to save time and effort for washing the used ink, and the number of usable colors of the water-based ink of this embodiment which is low in foam suppression Can be kept a lot.

(Water-based ink)
The water-based ink used for the printing layer of this embodiment adds a solvent to the structure of the water-based ink coating part of a dry state. That is, the aqueous ink contains a colorant, a binder resin, and a solvent.
In addition, water-based inks may also contain auxiliary agents (for example, polyolefin-based waxes such as polyethylene wax; fatty acids amide, fatty acid ester, paraffin wax, various known waxes such as polytetrafluoroethylene (PTFE) wax and carnauba wax) The ink composition may contain various ink additives such as leveling agents, antifoaming agents, pigment dispersants, and lubricants.

着色 Colorant The colorant may be an inorganic colorant or an organic colorant.
Examples of inorganic colorants include titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, aluminum hydroxide, talc, clay, kaolin, chromium oxide, silica, carbon black, aluminum, mica (mica), etc. It can be mentioned.
From the viewpoint of coloring power, hiding power, chemical resistance and weather resistance, titanium oxide is preferable as the white colorant, and titanium oxide in which the pigment surface is basic is more preferable. Aluminum is in the form of powder or paste, but is preferably used in the form of paste in terms of handleability and safety. Whether to use leafing or non-leafing is appropriately selected in terms of brightness and density.
Barium sulfate, calcium carbonate, aluminum hydroxide, talc, clay and kaolin are called extender pigments and are used as extenders to improve flowability, strength and optical properties.
On the other hand, organic colorants include organic pigments and dyes used in common inks, paints, recording agents and the like. For example, these include azo type, phthalocyanine type, anthraquinone type, perylene type, perinone type, quinacridone type, thioindigo type, dioxazine type, dioxazine type, isoindolinone type, quinophthalone type, azomethine azo type, dictopyrrolopyrrole type, isoindoline type etc. The content of the coloring agent can be appropriately selected in consideration of the desired color tone and the like of the ink, but generally it may be 50% by weight or less based on the total weight of the water-based ink, and the upper limit value By being the following, it becomes content of the coloring agent which can obtain the required inking density.

  When the water-based ink used in the present embodiment is white, the content of the white pigment may be generally 20% by weight or more and 50% by weight or less based on the total weight of the water-based ink. As a result, the pigment content is such that the required ink deposition concentration can be obtained. The white pigment is preferably titanium dioxide from the viewpoints of hiding power, pigment concentration and light resistance. When the water-based ink used in the present embodiment is colored, examples of colored pigments included include colored organic pigments and colored inorganic pigments such as bengal, bitumen, ultramarine, carbon black and graphite. Be From the viewpoint of color developability and light resistance, the colored pigment is preferably an organic pigment. The content of the colored pigment may generally be 10% by weight or more and 30% by weight or less based on the total weight of the aqueous ink, and by being within the above range, a pigment with which the required oncoming density can be obtained It becomes content.

  The aqueous ink used in the present embodiment preferably further contains an extender pigment. The aqueous ink used in the present embodiment contains a large amount of urethane resin as described later. Therefore, although the water-based ink coated part after foaming becomes sticky easily, in the present embodiment, by including the body pigment, the stickiness of the water-based ink coated part after foaming can be suppressed while maintaining a large content of the urethane resin. it can. Furthermore, it is possible to adjust the brightness, gloss and touch after processing of the foamable paper product.

  Examples of the extender pigment include silicon dioxide and the like. The silicon dioxide may be, for example, a compound known as "synthetic silica" which is produced by known methods. A typical preparation method of synthetic silica is a wet method of producing ultra-fine powder hydrous silicic acid by reacting sodium silicate and acid from high purity silica sand as raw materials, or combustion hydrolysis of silicon tetrachloride in the gas phase There is a dry method depending on the situation.

The silicon dioxide used in the present embodiment is not particularly limited by the synthesis method, and examples thereof include untreated silicon dioxide (untreated silica) and the like.
The particle diameter of silicon dioxide 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 silicon dioxide having a particle diameter equal to or more than the above lower limit value, it is possible to prevent the viscosity of the aqueous ink from increasing and to prevent the ink state from being reduced. Further, by using silicon dioxide having a particle diameter equal to or less than the above upper limit, it is possible to prevent the ink layer from following the foaming of the low melting point resin film which is used as a foaming thermoplastic resin at the time of heat treatment. be able to.

  The particle diameter of silicon dioxide is generally measured by the Coulter counter method using electrical resistance change, the laser method using light scattering, or the like. In this embodiment, it means an average particle size obtained by measurement using a laser method.

  When silicon dioxide is contained in the present embodiment, the content of silicon dioxide is preferably 0.2% by mass or more and 5% by mass or less, based on the total mass of the aqueous ink, and 0.5% by mass or more. It is more preferable that it is 5 mass% or less. When the content of silicon dioxide is in the above range, the viscosity can be adjusted to be easy to handle as an aqueous ink. Furthermore, it is possible to adjust the feeling of brightness and the feeling of touch after processing into a foamable paper product.

バ イ ン ダ ー Binder resin The binder resin contains a urethane resin having a glass transition temperature of −20 ° C. or more and 30 ° C. or less, preferably −15 ° C. or more and 0 ° C. or less, and in the resin solid of the binder resin, the urethane resin Is preferably contained 30% or more, more preferably 50% or more, still more preferably 70% or more, and particularly preferably 90% or more.
When the glass transition point of the urethane resin is −20 ° C. or higher, the occurrence of blocking can be suppressed, and when the temperature is 30 ° C. or lower, suppression of foaming can be suppressed.
In addition, "blocking" generally means that the surface which has a printing layer of a raw material sheet | seat, and the surface on the opposite side stick, when printing, drying of an ink, and winding up succeedingly.
When the amount of the urethane resin contained in the binder resin is in the above range, the foaming of the thermoplastic resin is hardly suppressed, and a raw material sheet with a smooth printing surface can be obtained.

○ Urethane-based resin As urethane-based resins such as polyurethane resin and polyurethane urea resin, urethane-based resins for printing ink commonly known can be selected and used. For example, urethane resins obtained by reacting a high molecular weight polyol with a polyisocyanate can be mentioned.

Polymer polyols As polymer polyols usable for urethane resins, polyether polyols such as PEG (polyethylene glycol), PPG (polypropylene glycol) and PTMG (polyoxytetramethylene glycol); ethylene glycol, 1 , 2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentadiol, methylpentadiol, hexadiol, octanediol, nonanediol, methylnonanediol And low molecular weight glycols such as diethylene glycol, triethylene glycol and dipropylene glycol, and adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid and ma Polyester polyols obtained by dehydrating condensation with an acid, glutaric acid, pimelic acid, azelaic acid, sebacic acid, dibasic acid such as dimer acid, or an anhydride thereof; other polycarbonate diols, polybutadiene glycols, bisphenol Various known polyols such as glycols and dimer diols obtained by adding ethylene oxide or propylene oxide to A can be mentioned.
These high molecular weight polyols may be used alone or in combination of two or more. Among them, as the high molecular weight polyol, it is preferable to contain a polyether polyol from the viewpoint of resolubility of aqueous ink, and it is more preferable to contain PEG (polyethylene glycol).

-Polyisocyanate Moreover, as polyisocyanate which can be utilized for urethane type resin, various well-known diisocyanates, such as aromatic, an aliphatic, or an alicyclic, can be mentioned, for example. More specifically, 1,5-naphthyl diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, cyclohexane 1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate Dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethyl xylylene diisocyanate, and dimeric isocyanate obtained by converting the carboxy group of dimer acid into isocyanate group Etc.

· Introduction of Carboxy Group To introduce a carboxy group into the resin, a polyol having a carboxy group can be used. Examples of the polyol having a carboxy group include dimethylol alkanoic acids such as 2, 2-dimethylol propionic acid, 2, 2- dimethylol butyric acid and 2, 2- dimethylol valeric acid; glutamine, asparagine, lysine, diamino propionic acid, And diamine type amino acids such as ornithine, diaminobenzoic acid and diaminobenzenesulfonic acid. These may be used alone or in combination of two or more.

  In the production of a polyurethane urea resin, a polymer polyol, a polyisocyanate, and a polyol containing a carboxy group are reacted to form a polyurethane resin, and then a urea bond is introduced using a chain extender and a reaction terminator. , Can be synthesized. When the urethane resin used for the water-based ink of the present embodiment is a polyurethane urea resin, by having a urea bond, the coating film tends to be tougher and the coating film physical properties tend to be improved.

-Chain extender As a chain extender which can be utilized when introduce | transducing a urea bond, various well-known amines can be used. Examples of the amines include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropyl. Ethylenediamine, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, dimer diamine obtained by converting the carboxy group of dimer acid to amino group, and the like can be mentioned. 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 the resolubility tends to be good.

· Reaction terminator As the reaction terminator, for example, dialkylamines such as di-n-dibutylamine, monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, tri (hydroxymethyl) aminomethane Hydroxyl groups such as 2-amino-2-ethyl-1,3-propanediol, N-di-2-hydroxyethylethylenediamine, N-di-2-hydroxyethylpropylenediamine, N-di-2-hydroxypropylethylenediamine, etc. Aminoamines such as glycine, alanine, glutamic acid, taurine, aspartic acid, aminobutyric acid, valine, aminocaproic acid, aminobenzoic acid, aminoisophthalic acid, sulfamic acid and the like. The above reaction terminator may be used alone or in combination of two or more.

-Neutralizing agent In order to make polyurethane resin and polyurethane resin, such as polyurethane urea resin, water-solubilizing, it is preferable to neutralize a part or all of the carboxy group in resin with a basic compound. Examples of the basic compound include sodium hydroxide, potassium hydroxide, ammonia, methylamine, ethylamine, propylamine, butylamine, hexylamine, 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, morpholine and the like. These neutralizing agents may be used alone or in combination of two or more. Among them, ammonia is preferable as the neutralizing agent in the present embodiment from the viewpoint of water resistance of printed matter, residual odor and the like.

· Synthesis method As a synthesis method of urethane resin such as polyurethane resin and polyurethane urea resin, for example, acetone method using an organic solvent inert and hydrophilic to isocyanate, solvent-free synthesis method using no solvent, etc. Can be mentioned. Examples of organic solvents which are inert and hydrophilic to isocyanates include ethers such as tetrahydrofuran and dioxane, esters such as ethyl acetate, ketones such as acetone, methyl ethyl ketone and cyclohexanone, dimethylformamide, N-methylpyrrolidone And the like. It is preferable to use a solvent having a boiling point lower than that of water, because the organic solvent is usually removed by distillation under reduced pressure (solvent removal), and in order to accelerate the drying speed even when used without solvent removal. In the case of removing the solvent, for example, water and a basic compound may be added to the reaction solution.

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

Acrylic-based monomer The acrylic-based monomer is not particularly limited and, for example, methyl (meth) acrylate (here, methyl acrylate or methyl methacrylate) is shown. Alkyl group-containing (meth) acrylic units such as ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. Bodies; hydroxyl group-containing (meth) acrylic monomers such as 2-hydroxyethyl (meth) acrylate; ethylenically unsaturated carboxylic acids such as (meth) acrylic acid; dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate ) Amino group-containing (meth) acrylic single unit such as acrylate Amide-containing (meth) acrylic monomers such as (meth) acrylamide and ethyl (meth) acrylamide; nitrile group-containing (meth) acrylic monomers such as acrylonitrile; epoxy group-containing glycidyl (meth) acrylates ( Meta) acrylic monomer etc. are mentioned.

-Other monomer copolymerizable with acrylic monomer The other monomer copolymerizable with the acrylic monomer includes, for example, aromatics such as styrene, methylstyrene, chlorostyrene, vinyl toluene and the like Hydrocarbon-based vinyl monomers; α, β-ethylenically unsaturated carboxylic acids such as maleic acid, itaconic acid, crotonic acid, fumaric acid and citraconic acid; sulfonic acid-containing vinyl monomers such as styrene sulfonic acid and vinyl sulfonic acid Acid anhydride such as maleic anhydride and itaconic acid; chlorine-containing monomer such as vinyl chloride, vinylidene chloride and chloroprene; hydroxyl group-containing alkyl vinyl ether such as hydroxyethyl vinyl ether and hydroxypropyl vinyl ether; ethylene glycol monoallyl Ether, propylene glycol monoallyl ether diethylene glycol mono Alkylene glycol monoallyl ethers such as allyl ether; α-olefins such as ethylene, propylene and isobutylene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate and vinyl pivalate; methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether And vinyl ethers such as ethyl allyl ether and butyl allyl ether.

Synthetic Method An emulsion of these acrylic resins is obtained, for example, by an emulsion polymerization method. There is no particular limitation on the method of emulsion polymerization, and the above-mentioned various monomers, chain transfer agents, surfactants, radical polymerization initiators, and other additives used as needed are used in a conventionally known method in an aqueous medium. The monomer can be polymerized to produce an emulsion in a dispersion system in which the agent component is a basic composition component.

○ Other resin The binder resin may further contain a polyamide resin or a polyester resin.

-Polyamide resin The said polyamide resin has an amide bond in a principal chain, and can be obtained by the dehydration condensation reaction which used dicarboxylic acid and diamine, for example.
Examples of the dicarboxylic acid include dimers obtained by dimerizing unsaturated fatty acid having 18 carbon atoms such as adipic acid, azelaic acid, sebacic acid, pimelic acid, suberic acid, nonane dicarboxylic acid, fumaric acid, oleic acid and linoleic acid An acid etc. are mentioned.
These dicarboxylic acids may be used alone or in combination of two or more.
Examples of the diamine include ethylenediamine, hexamethylenediamine, tetramethylenediamine, pentamethylenediamine, m-xylenediamine, phenylenediamine, diethylenetriamine, piperazine and the like.
These diamines may be used alone or in combination of two or more.

-Polyester resin For example, the polyester resin is (1) a method of polycondensing a predetermined acid and alcohol, (2) a method of polycondensing a predetermined acid and alcohol and then depolymerizing with a polybasic acid, or (3) It can manufacture by well-known methods, such as the method of adding an acid anhydride, after polycondensing a predetermined | prescribed acid and alcohol.

As the acid constituting the polyester resin, at least a polybasic acid may be used, and if necessary, a monocarboxylic acid may be mixed and used.
As said polybasic acid, aromatic dicarboxylic acid, aliphatic dicarboxylic acid, alicyclic dicarboxylic acid etc. are mentioned, for example.
Specific examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, naphthalene dicarboxylic acid, biphenyl dicarboxylic acid and the like.
Specific examples of aliphatic dicarboxylic acids include, for example, oxalic acid, malonic acid, succinic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, hydrogenated dimer acid And unsaturated aliphatic dicarboxylic acids such as fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic acid, citraconic acid, citraconic acid, dimer acid and the like.
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-norbornene anhydride Dicarboxylic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride and the like can be mentioned.
Further, as the polybasic acid, a small amount of 5-sodium sulfoisophthalic acid or 5-hydroxyisophthalic acid may be used, if necessary.
Tribasic or higher polybasic acids can also be used, such as trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid, trimellitic anhydride, pyromellitic anhydride, benzozophenone tetracarboxylic acid anhydride, trimesic acid, ethylene Glycol bis (anhydrotrimellitate), glycerol tris (anhydrotrimellitate), 1,2,3,4-butanetetracarboxylic acid and the like can be mentioned.

  As specific examples of the monocarboxylic acid, for example, fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, p-tert-butylbenzoic acid, cyclohexane acid, 4 -Hydroxyphenyl stearic acid etc. are mentioned.

  As the alcohol constituting the polyester resin, at least a polyhydric alcohol may be used, and if necessary, a monoalcohol may be mixed and used.

Examples of the polyhydric alcohol include aliphatic glycol, alicyclic glycol, glycol containing ether bond and the like.
Specific examples of aliphatic glycols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5- Pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol and the like can be mentioned.
As a specific example of alicyclic glycol, a 1, 4- cyclohexane dimethanol etc. are mentioned, for example.
Specific examples of the ether bond-containing glycol include, for example, diethylene glycol, triethylene glycol, dipropylene glycol; ethylene oxide adducts of bisphenols such as 2,2-bis [4- (hydroxyethoxy) phenyl] propane (bisphenol A); Ethylene oxide adducts of bisphenols (bisphenol S) such as bis [4- (hydroxyethoxy) phenyl] sulfone; polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like.
Trihydric or higher polyhydric alcohols can also be used, and examples thereof include glycerin, trimethylol ethane, trimethylol propane, pentaerythritol and the like.

As a specific example of monoalcohol, stearyl alcohol, 2-phenoxy ethanol etc. are mentioned, for example.

In order to make the polyester resin water soluble, it is preferable to neutralize some or all of the carboxy groups in the resin with a basic compound. As said basic compound, the thing similar to what was illustrated in the above-mentioned ". Neutralizing agent" is mentioned.

In the present embodiment, the binder resin preferably contains a resin other than a urethane resin in total at 70% or less, more preferably 50% or less, still more preferably 30% or less. It is particularly preferable to contain the following.
Since the amount of the resin other than the urethane resin in the binder resin is within the above range, the urethane resin is sufficiently contained, so that the foaming of the thermoplastic resin is not suppressed, and the raw material sheet on the smooth printing surface is You can get

  In the present embodiment, the content of the binder resin is preferably 15% by mass or more and 25% by mass or less based on the total mass of the aqueous ink. When the content of the binder resin is not less than the above lower limit value, an appropriate ink viscosity can be obtained, and by being not more than the above upper limit value, the flowability of the ink is prevented from being lowered, and at the time of ink production and printing Work efficiency can be improved.

溶 剤 Solvent In the present embodiment, the solvent may be a known compound which can be generally used as a solvent for aqueous ink. For example, water; alcohol solvents such as methanol, ethanol, isopropanol, n-propanol, n-butanol and the like, and the like, can be mentioned without limitation. These solvents may be contained alone, or a mixture of two or more may be contained.

(Foaming suppression ink)
The anti-foaming ink used for the printing layer of the present embodiment is a composition in which a solvent is added to the configuration of the anti-foaming ink coating portion in a dry state. That is, the foam suppression ink contains a binder resin and a solvent.
Furthermore, if necessary, the antifoaming ink may contain various ink additives such as auxiliaries, pigment dispersants, leveling agents, surfactants, and antifoaming agents.
Moreover, the foam suppression ink may contain a colorant and may not contain a colorant. In order to make it easy to see the unevenness on the appearance, it is preferable that the color does not differ greatly between the foam part and the foam suppression part. For that purpose, the foam suppression ink does not contain a colorant or The content is preferably at most 20% by weight, more preferably at most 10% by weight.
Therefore, the foam suppression ink coating part 1c may be colored or colorless. In the case of colorless or pale color, it is preferable from the viewpoint that the unevenness of the foam portion 4, the first print foam portion 5a, and the second print foam portion 5b and the foam suppression ink coating portion 1c is easily visible. Moreover, even if it is colored, when setting it as pale blue or green of a cold color type | system | group, it is preferable from the point which an unevenness | corrugation is emphasized deeply and it becomes easy to see.

  As said coloring agent, adjuvant, and a solvent, the thing similar to what was illustrated by the above-mentioned (water-based ink) is mentioned.

The binder resin contains a resin having a glass transition temperature of 60 ° C. or more and 120 ° C. or less, and preferably 70% by mass or more, and 80% by mass or more of the resin solid content of the binder resin. Is more preferable, and containing 90% by mass or more is more preferable. By containing 70% by mass or more of a resin having a glass transition point in the above range, a high foam suppression 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 higher than 120 ° C. in the foam suppression ink coating portion 1 c is preferably less than 30% by mass, and 20% by mass It is more preferably less than 10% by mass.

Moreover, it is preferable that the glass transition point of the said resin is 60 to 120 degreeC.
By using a foam suppression ink containing a glass transition point in the above range, even in the case of an aqueous flexographic printing method having a small ink coating amount, the foam can be sufficiently suppressed in one printing, and the unevenness is obtained. By controlling, it is possible to impart excellent design to the printing surface.
As a resin of the said glass transition point 60 to 120 degreeC, acrylic resin, a polyester resin, etc. are mentioned, for example, It is not limited to these.

The acrylic resin has a glass transition point of 60 ° C. among the acrylic monomers exemplified in the above-mentioned “○ acrylic resin” and other monomers copolymerizable with the acrylic monomer. It may be synthesized by appropriately selecting and polymerizing so as to be 120 ° C. or lower.
Further, as the polyester resin, for example, after polycondensing various acids and various alcohols using various acids and various alcohols exemplified in the above-mentioned “polyester resin”, depolymerization is performed with various polybasic acids. In the synthesis method, the kind of the acid and the alcohol may be appropriately selected so that the glass transition temperature is 60 ° C. or more and 120 ° C. or less, and the synthesis may be performed by controlling the ratio of depolymerization.

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

[Foamed thermoplastic resin layer]
In the raw material sheet of the present embodiment, the foam layer is formed by heating the thermoplastic resin layer. That is, the foam layer is a foamed thermoplastic resin layer (foamed thermoplastic resin layer). The thermoplastic resin used for the foamed thermoplastic resin layer is not particularly limited as long as extrusion lamination is possible and foaming is possible, and any thermoplastic resin of crystalline resin and non-crystalline resin can be used. . Examples of crystalline resins include polyolefin resins such as polyethylene, polypropylene and polymethylpentene; polyester resins, polyamides, polyacetals and PPS resins. Examples of the non-crystalline resin include polystyrene, polyvinyl chloride, ABS resin, acrylic resin, modified PPE, polycarbonate, polyurethane, polyvinyl acetate, non-crystalline polyethylene terephthalate (PET) and the like. As melting | fusing point of these thermoplastic resins, about 80-120 degreeC is preferable. The thermoplastic resin may be a single resin in a single layer or a plurality of resins in a double layer, but is preferably a single layer from the viewpoint of foamability.

Among them, as a thermoplastic resin used for the foamed thermoplastic resin layer, polyethylene is preferable because it is excellent in laminate suitability and foamability. Polyethylene is roughly divided into linear low density polyethylene, low density polyethylene, medium density polyethylene, and high density polyethylene.
As the density, linear low density polyethylene is 888 to 910 kg / m ³ , low density polyethylene is 910 kg / m ^{3 to} 925 kg / m ³ , and medium density polyethylene is 925 kg / m ^{3 to} 940 kg / m ³ or more. Density polyethylene is 940 kg / m ³ or more and 970 kg / m ³ or less.
The melting point of linear low density polyethylene is 55 ° C. to 120 ° C., low density polyethylene is 105 ° C. to 120 ° C., medium density polyethylene is 120 ° C. to 125 ° C., and high density polyethylene is 125 ° C. to 135 ° C. It is below.

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

[Non-foamed thermoplastic resin layer]
In the raw material sheet of the present embodiment, in order to enhance the foaming efficiency, the wall surface opposite to the wall surface having the foamed thermoplastic resin layer of the body member is made of a thermoplastic resin having a melting point higher than that of the foamed thermoplastic resin layer It is preferable to coat with a thermoplastic resin layer (non-foamed thermoplastic resin layer) which does not foam at the time or an aluminum foil or the like. If one side of the paper base is bare (in a state where it is not covered with a laminate or a coated layer), the moisture in the paper will evaporate from the uncoated side into the air during heat treatment, which is sufficiently certain Foaming becomes difficult. Therefore, by providing such a covering layer, the moisture in the paper can be efficiently contributed to the foaming. When the raw material sheet is used as a foamable paper container, when the non-foamed thermoplastic resin layer, the aluminum foil, etc. are present on the inner wall surface side of the body member, the filling liquid etc. penetrates into the paper. Can be prevented.

The thermoplastic resin used for 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. If they are the same, the melting point can be made different by giving a difference in density. For example, when selecting polyethylene as a thermoplastic resin of both, let a foaming thermoplastic resin layer be low density polyethylene, and let a non-foaming thermoplastic resin layer be medium density or high density polyethylene. The difference between the melting points of the thermoplastic resin of the foamed thermoplastic resin layer and the non-foamed thermoplastic resin layer is preferably 5 ° C. or more, and the melting point of the thermoplastic resin of the non-foamed thermoplastic resin layer is melted when heated. It is not particularly limited as long as diffusion of evaporated water can be prevented, but it is preferably 125 ° C. or higher.

[Paper base material]
The paper base used for the raw material sheet of the present embodiment is mainly made of, for example, chemical pulp and mechanical pulp obtained from wood, to which non-wood pulp such as kenaf and bamboo is blended according to need, usually The paper base material obtained by making into a paper by the papermaking process of 4 is mentioned, It is not limited to this. Among them, the paper base used for the raw material sheet of the present embodiment preferably contains chemical pulp. Containing chemical pulp makes it easier to increase the density compared to using mechanical pulp, and suppresses yellowing when exposed to light for a long time or stored at high temperature for a long time In addition, the strength and rigidity of the container can be increased.
80 weight% or more is preferable, as for the compounding ratio of the chemical pulp with respect to the total raw material pulp used for a paper base material, 90 weight% or more is more preferable, and 95 weight% or more is further more preferable.
In addition, it is preferable that the chemical pulp contains a large amount of softwood-derived fibers because the foamability is high.
5% or more is preferable, as for the compounding ratio of the softwood origin chemical pulp with respect to all the raw material pulp used for a paper base material, 10% or more is more preferable, and 20% or more is more preferable.

The base paper basis weight of the paper base may be, for example, 25 g / m ² or more and 500 g / m ² or less. Also, when using a raw material sheet of the present embodiment to the container, the base paper grammage of the paper substrate may if considering the foaming example 30 g / m ² or more 400 g / m ² or less.
When the base paper basis weight of the raw material sheet of the present embodiment is not less than the above lower limit value, it is possible to sufficiently secure the heat insulation property by foaming and the water content necessary for providing the design. In addition, when the base paper basis weight of the raw material sheet of the present embodiment is not more than the above upper limit value, it is easy to process after foaming, and the cost of the paper substrate can be suppressed within an appropriate range.

  The freeness ("Canadian Standard" freeness; CSF) of the pulp used for the paper substrate is preferably 150 mL or more and 600 mL or less, and more preferably 200 mL or more and 580 mL or less. When the CSF of the pulp is 600 mL or less, water vapor is difficult to permeate through the inside of the paper base and it is difficult for the water vapor to escape from the end face of the paper base, so the foamed thickness becomes large. When the CSF of the pulp is 200 mL or more, the power consumption for refining the pulp to lower the freeness is not large and the cost is excellent. In addition, it is possible to ease the equipment response to enhance the pulp refining capacity.

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.

  Generally as a manufacturing method of a paper base material, the stock prepared by adding the above-mentioned pulp, water, and a filler, other medicines etc. if needed, is sprayed on the wire of a paper machine, Dewatering, press watering in the press part, drying in the dryer part, then make a paper with a size press that gives strength and water resistance to the paper if necessary, and calendering to adjust the unevenness of the paper surface, and finish the paper The paper is taken up and finished to a predetermined take-up dimension. Also, in order to impart paper strength and water resistance to paper, chemicals such as polyvinyl alcohol (PVA), starch, surface sizing agents, etc. may be used alone or in combination of two or more kinds as appropriate. In addition, manufacture of the paper base material in this embodiment is not limited to this.

<Method of manufacturing raw material sheet>
In one embodiment, the present invention is a method for producing a raw material sheet used for a foamable paper product, which comprises a thermoplastic resin layer forming step of forming a thermoplastic resin layer on at least one side of a paper substrate, and the thermoplastic resin An aqueous ink coated portion forming step of applying the above-mentioned aqueous ink to the surface on which the thermoplastic resin layer is formed among the paper base material after the layer forming step and drying to form an aqueous ink coated portion; A foaming method is provided, comprising the step of foaming the thermoplastic resin layer after the aqueous ink coated portion forming step to form a foamed layer consisting of a normal foaming portion and a printing foam portion.

According to the manufacturing method of this embodiment, it is a smooth printing surface and can obtain a raw material sheet excellent in thermal insulation.
Each step will be described in detail below.

[Thermoplastic resin layer forming process]
First, a thermoplastic resin layer is formed on at least one side of a paper substrate.
There is no particular limitation on the method for forming the thermoplastic resin layer, and for example, if laminating using a method of laminating with a film made in advance such as extrusion lamination method, wet lamination method, dry lamination method, etc., as appropriate, Good. Among them, as a method of forming a thermoplastic resin layer, an extrusion laminating method is preferable from the viewpoint of adhesion to a paper substrate, foamability, and the like. The extrusion laminate is, for example, extruding a thermoplastic resin layer in the form of a molten resin film from a T-die on the surface of a paper substrate to which a foam promoting agent is applied, and cooling between a cooling roll and an opposing nip roll. It is a method of pressing while doing. In extrusion lamination, the operating conditions such as the melting temperature of the resin and the lamination speed are not particularly limited as long as they are appropriately set depending on the type and apparatus of the resin used, but generally, for example, the melting temperature is 200 ° C or more and 350 ° C or less, the lamination speed Is 50 m / min or more and 200 m / min or less. Further, it is preferable to use a nip roll having a hardness of 70 degrees or more (JIS K-6253), and to perform pressing and pressure bonding at a linear pressure of 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.

  As a thickness of the thermoplastic resin layer (foamed thermoplastic resin layer before heating), when forming a foamed layer (foamed thermoplastic resin layer) after heating, it is thick enough to provide desired heat insulation. Although it is not particularly limited as long as it is long, for example, it may be 20 μm or more and 90 μm or less.

  Moreover, about the thickness of the non-foaming thermoplastic resin layer before a heating, it is sufficient if it is a thickness sufficient to prevent scattering of evaporation water, for example, is 20 micrometers or more and 50 micrometers or less.

[Water-based ink coating part formation process]
Next, an aqueous ink is applied on the formed thermoplastic resin layer to form an aqueous ink coated portion.
As the water-based ink, the same one as exemplified in the above (water-based ink) may be used.
The method for applying the aqueous ink on the thermoplastic resin layer is not particularly limited, and examples thereof include an aqueous gravure printing method, an aqueous flexographic printing method, and a screen printing method. Among them, as a method of applying an aqueous ink to a paper substrate, an aqueous flexographic printing method which can be applied at a low coating amount is preferable. The water-based ink used in the present embodiment is colored similarly to the water-based gravure printing method even if the water-based flexographic printing method has a low coating amount, and clear printing can be obtained.

[Foaming process]
Next, the thermoplastic resin layer is heat-treated to foam the thermoplastic resin layer, thereby forming a foam layer comprising a usual foam portion and a print foam portion.

  The heating temperature and heating time vary depending on the type of paper substrate and thermoplastic resin used, and the optimum combination of heating temperature and heating time for the thermoplastic resin used can be appropriately determined, but the heating temperature is A temperature slightly higher than the melting point of the thermoplastic resin that foams (melting point + 5 ° C to 30 ° C) is suitable, and generally the heating temperature is 110 ° C to 200 ° C, and the heating time is 1 minute to 6 minutes. is there. A heating means is not specifically limited, For example, arbitrary means, such as a hot air, an electric heat, an electron beam, can be used. If it heats with a hot air or an electric heat etc. in the tunnel provided with the conveyance means by a conveyor, it can mass-produce inexpensively.

[Step of forming anti-foaming ink coating portion]
In the manufacturing method of this embodiment, it is after an aqueous | water-based ink coating part formation process, Comprising: Before a foaming process, you may provide the bubble suppression ink coating part formation process.
After the solvent of the water-based ink is dried and the water-based ink coated portion is formed, the anti-foaming ink is applied to form the anti-foaming ink coated portion.
As the foam suppression ink, the same one as exemplified in the above-mentioned (foam suppression ink) may be used.
There is no particular limitation on the method for applying the antifoaming ink on the thermoplastic resin layer, and an aqueous gravure printing method, an aqueous flexographic printing method, a screen printing method and the like can be mentioned. Among them, as a method of applying the antifoaming ink to a paper substrate, an aqueous flexographic printing method which can be applied at a low coating amount is preferable.

  The obtained raw material sheet may be further processed using a known method so as to be in a desired form according to the application as exemplified in <Application> described later.

<Use>
The raw material sheet of the present embodiment is used for a paper product having a heat insulating property and a smooth printing surface, and specifically, for example, a foamable paper cup, a foamable paper container, a brochure, a fancy paper , Wrapping paper, wallpaper etc.

[Foamable paper container]
In one embodiment, the present invention provides a foamable paper container comprising the above-mentioned raw material sheet.

  The foamable paper container of the present embodiment has a smooth printing surface, it is difficult for heat to be transmitted to the hand, and it has excellent heat insulation in practical use.

The foamable paper container of the present embodiment can be manufactured, for example, by the following method.
First, the raw material sheet is unrolled from the winding roll. Subsequently, the blank for the body member and the blank for the bottom plate member are punched from the raw material sheet, and assembled into a container shape by a common cup forming machine. Here, the foamed thermoplastic resin layer may be present on either or both of the outer wall surface side and the inner wall surface side of the trunk member, as long as heat insulation, touch, appearance aesthetics, etc. are appropriately determined as desired. Although it is preferable, when the inside of the container is a foamed surface, the foamed resin may be damaged by a bag, a fork or the like at the time of eating and drinking and may enter the mouth, so it is preferable to be on the outer wall side. Thus, for example, the body 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, one provided with a non-foamed thermoplastic resin layer is preferably used on at least one side of the inner surface of the paper base of the paper substrate. This is to prevent the penetration of liquid or the like into the paper. The thermoplastic resin used for the bottom plate member may be the same as or different from that of the body member, and the laminating method is also the same as that of the film made in advance by wet laminating method, dry laminating method, etc. besides extrusion laminating method. Any suitable method can be used.

  In order to prevent heat radiation from the bottom of the container, it is effective to provide a foamed thermoplastic resin layer on the bottom member as well, such as cup noodles, which are left for a while after pouring hot water. In particular, it is preferable for outdoor use and in winter and cold regions. Moreover, you may use the thing which also has a foaming thermoplastic resin layer similarly.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Example 1
Low density polyethylene (made by Nippon Polyethylene Co., Ltd.) Brand name: LC 701 on one side of a paper base of 300 g / m ² (thickness 330 μm, density 0.91 g / cm ³ , chemical pulp 100%, moisture content 7.8%) A density of 0.918 g / cm ³ , melting point 106 ° C.) was extrusion laminated at a thickness of 70 μm. On the opposite side of the paper substrate, medium density polyethylene (manufactured by Tosoh Corporation, Brand Name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) was extrusion laminated with a thickness of 40 μm. On the surface of this low density polyethylene laminate film, water-based ink A (solid component content is 60% by mass of urethane resin (glass transition point 10 ° C.), 40% by mass of colorant. Solvent (ethanol: water = 10: 90) The total content of resin and colorant in the dispersed state is 40 mass%.) According to each printing pattern shown in Table 1 and using flexoproof 100 (manufactured by Matsuo Sangyo Co., Ltd.) I printed it. After printing, it was placed in an oven and heated at 120 ° C. for 120 seconds. The foam thickness in each ink coated portion is shown in Table 1. Moreover, about the foaming suppression rate in each ink coating part, it summarized in Table 3 and 5.

Example 2
Low density polyethylene low density polyethylene (made by Japan Polyethylene Corporation) on one side of a paper base of 300 g / m ² (thickness 330 μm, density 0.91 g / cm ³ , chemical pulp 100%, moisture content 7.8%) : LC 701, density 0.918 g / cm ³ , melting point 106 ° C.) were extrusion laminated at a thickness of 70 μm. On the opposite side of the paper substrate, medium density polyethylene (manufactured by Tosoh Corporation, Brand Name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) was extrusion laminated with a thickness of 40 μm. On the surface of this low density polyethylene laminate film, water-based ink B (solid component content is 60% by mass of urethane resin (glass transition point 10 ° C.), 40% by mass of colorant. Solvent (ethanol: water = 20: 80) The total content of resin and colorant in the dispersed state is 40% by mass.) According to each printing pattern shown in Table 1 using each color of printing test machine (gravure auto puller, manufactured by Matsuo Sangyo Co., Ltd.) It gravure-printed using. After printing, it was placed in an oven and heated at 120 ° C. for 120 seconds. The foam thickness in each ink coated portion is shown in Table 1. Moreover, about the foaming suppression rate in each ink coating part, it summarized in Table 3 and 5.

[Example 3]
Low-density polyethylene low-density polyethylene (made by Japan Polyethylene Corporation) on one side of a paper base of 260 g / m ² (thickness 280 μm, density 0.93 g / cm ³ , chemical pulp 100%, moisture content 7.6%) : LC 701, density 0.918 g / cm ³ , melting point 106 ° C.) were extrusion laminated at a thickness of 70 μm. On the opposite side of the paper substrate, medium density polyethylene (manufactured by Tosoh Corporation, Brand Name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) was extrusion laminated with a thickness of 40 μm. On the surface of this low density polyethylene laminate film, water-based ink A (solid component content is 60% by mass of urethane resin (glass transition point 10 ° C.), 40% by mass of colorant. Solvent (ethanol: water = 10: 90) The total content of the resin and colorant in the dispersed state is 40% by mass, and 20% by mass of the foam suppressing ink F (acrylic resin (glass transition point 90 ° C.), solvent (ethanol: water) Flexo printing was performed using a printer according to each printing pattern shown in Table 1 using (= 10: 90) 80% by mass). After printing, it was placed in an oven and heated at 120 ° C. for 120 seconds. The foam thickness in each ink coated portion is shown in Table 1. Moreover, about the foaming suppression rate in each ink coating part, it summarized in Table 3 and 6.

Example 4
Low density polyethylene (made by Nippon Polyethylene Co., Ltd.) Brand name: LC 701 on one side of a paper base of 135 g / m ² (thickness 201 μm, density 0.67 g / cm ³ , chemical pulp 100%, moisture content 7.0%) A density of 0.918 g / cm ³ , melting point 106 ° C.) was extrusion laminated at a thickness of 15 μm. A medium density polyethylene (trade name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) manufactured by Tosoh Corp. was extrusion laminated on the opposite side of the paper substrate to a thickness of 45 μm. On the surface of this low density polyethylene laminate film, water-based ink A (solid component content is 60% by mass of urethane resin (glass transition point 10 ° C.), 40% by mass of colorant. Solvent (ethanol: water = 10: 90) The total content of the resin and colorant in the dispersed state is 40% by mass, and 20% by mass of the foam suppressing ink F (acrylic resin (glass transition point 90 ° C.), solvent (ethanol: water) Flexo printing was performed using a printer according to each printing pattern shown in Table 1 using (= 10: 90) 80% by mass). After printing, it was placed in an oven and heated at 130 ° C. for 180 seconds. The foam thickness in each ink coated portion is shown in Table 1. Moreover, about the foaming suppression rate in each ink coating part, it summarized in Table 3 and 6.

Comparative Example 1
Low density polyethylene (made by Nippon Polyethylene Co., Ltd.) Brand name: LC 701 on one side of a paper base of 300 g / m ² (thickness 330 μm, density 0.91 g / cm ³ , chemical pulp 100%, moisture content 7.8%) A density of 0.918 g / cm ³ , melting point 106 ° C.) was extrusion laminated at a thickness of 70 μm. On the opposite side of the paper substrate, medium density polyethylene (manufactured by Tosoh Corporation, Brand Name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) was extrusion laminated with a thickness of 40 μm. On the surface of this low density polyethylene laminate film, water-based ink C (content of solid component is 60% by mass of acrylic resin, 40% by mass of colorant) resin in a state of being dispersed in solvent (ethanol: water = 5: 95) And the total content of colorants is 40% by mass, and 20% by mass of foam suppressing ink G (acrylic resin (glass transition temperature 45 ° C.) 20% by mass, solvent (ethanol: water = 10: 90) 80% %, And flexo printing was performed using Flexoproof 100 (manufactured by Matsuo Sangyo Co., Ltd.) according to each printing pattern shown in Table 2. After printing, it was placed in an oven and heated at 120 ° C. for 120 seconds. The foamed thickness in each ink-coated portion is shown in Table 2. In addition, the foaming inhibition rate in each ink-coated portion is summarized in Tables 4, 5, and 6.

Comparative Example 2
Low density polyethylene (made by Nippon Polyethylene Co., Ltd.) Brand name: LC 701 on one side of a paper base of 300 g / m ² (thickness 330 μm, density 0.91 g / cm ³ , chemical pulp 100%, moisture content 7.8%) A density of 0.918 g / cm ³ , melting point 106 ° C.) was extrusion laminated at a thickness of 70 μm. On the opposite side of the paper substrate, medium density polyethylene (manufactured by Tosoh Corporation, Brand Name: LW04, density 0.940 g / cm ³ , melting point 131 ° C.) was extrusion laminated with a thickness of 40 μm. On the surface of this low density polyethylene laminate film, an oil-based ink D (solid component content is 30% by mass of urethane resin, 20% by mass of nitrifying cotton, 50% by mass of colorant), resin content in the state of ink is 10% The total of resin, nitrifying cotton, and coloring agent in the state of being dispersed in solvent (mixed solvent consisting of isopropyl alcohol (10%) / ethyl acetate (40%) / toluene (30%) / methyl ethyl ketone (20%)) The content rate was gravure printed using a printing tester (gravure auto puller, manufactured by Matsuo Sangyo Co., Ltd.) according to each printing pattern shown in Table 2 using each color of 20% by mass. After printing, it was placed in an oven and heated at 120 ° C. for 120 seconds. The foamed thickness in each ink-coated portion is shown in Table 2. In addition, Table 4 summarizes the foaming suppression rate in each ink coated portion.

From Table 3, in Example 1, Example 2, Example 3, and Example 4, the foam suppression ratio (1) is 19.0%, 38.3%, 21.1%, and 26.3%, respectively. From Table 4, Comparative Examples 1 and 2 showed 43.8% and 49.9%, which is higher than 40%.
Furthermore, from Table 3, in Example 1, Example 2, and Example 3, the foam inhibition ratio (2) is 26.0%, 46.7%, and 34.9%, respectively, which is 50% or less. On the other hand, according to Table 4, Comparative Examples 1 and 2 were 61.1% and 62.0%, which were higher than 50%.

  Moreover, from Table 5, in Example 1 and Example 3 which performed aqueous | water-based flexographic printing, foaming suppression ratio (3) is 10.3% and 17.5%, and was 20% or less, respectively. In Comparative Example 1 in which aqueous flexographic printing was also performed, it was 36.8% and was higher than 20%.

Further, from Table 6, in Examples 3 and 4 in which the foam suppression ink F was applied, the foam suppression rates were 45.9%, 44.8%, and 52.9%, and were 40% or more. On the other hand, in Comparative Example 1 where the antifoaming ink G was applied, it was 36.9% and 30.3%, which was lower than 40%.
From this, it became clear that, even in flexo printing having a low coating amount, by using the foam suppressing ink F, a sufficient foam suppressing effect can be obtained.

From the above, by using a water-based ink containing a urethane resin, the foam suppression ratio calculated from the foam thickness in the aqueous ink-coated portion of one layer to the foam thickness in the foam layer when the water-based ink is not applied is 40% The low density polyethylene can be suppressed to 20% or less, which can be suppressed to the following, and the expansion suppression ratio calculated from the expansion thickness in the two-layer water-based ink coated area to the expansion thickness in the one-layer water-based ink application area It was confirmed that a foamable paper product having a smooth film surface was obtained.
Moreover, even if it is flexo printing which is a low coating amount, unevenness is formed on the printing surface of the low density polyethylene film by using a foam suppression ink containing a resin having a glass transition point of 60 ° C. or more and 120 ° C. or less It was confirmed that a foamable paper product having excellent design was obtained.

  According to the present invention, there is provided a raw material sheet from which a foamable paper product is obtained which contains an ink with little influence on the environment and the printing layer surface is smooth and the appearance is excellent, and a foamable paper container made of the raw material sheet. be able to.

  A: Water-based ink non-coating area, B: Water-based ink coating area, X: Foaming thickness in the water-based ink non-coating portion (usually the foaming portion 4) Y: Foaming thickness in the 1 layer water-based ink coating portion, Y ': 2 layer Foam thickness in the water-based ink coated portion, Z: foam thickness in the anti-foaming ink coating portion, 1: print layer, 1a: first water-based ink coated portion, 1b: second water-based ink coated portion, 1c: foam suppression ink 2a: non-foamed thermoplastic resin layer, 2b: foamed thermoplastic resin layer, 2b ': foamed layer (foamed thermoplastic resin layer after heating), 3: paper base, 4: ordinary foamed portion, 5: Printing foam part, 5a: first printing foam part, 5b: second printing foam part, 5c: foam suppression part, 10, 30: raw material sheet before foaming, 20, 40: raw material sheet after foaming.

Claims (8)

Raw material sheet used for foamable paper products,
It consists of a paper base material provided with a foaming layer which heats a thermoplastic resin layer which has one or more water-based ink painting parts on at least one side,
Assuming that the foamed thickness in the foamed layer in the case where the aqueous ink is not applied is X and the foamed thickness in the aqueous ink-coated portion of one layer is Y, the foaming suppression ratio represented by the following formula [1] is 40% or less Raw material sheet characterized by that.

  The water-based ink contains a colorant and a binder resin, and the resin solid content of the binder resin contains 30% by mass or more of a urethane resin having a glass transition point of -20 ° C or more and 30 ° C or less. Raw material sheet.   The raw material sheet according to claim 1, wherein the water-based ink further contains an extender pigment.   The raw material sheet according to claim 3, wherein the extender pigment is silicon dioxide.   Furthermore, the raw material sheet as described in any one of Claims 1-4 in which the said foam layer is equipped with a foaming suppression part. The foam suppression portion is formed by heating a thermoplastic resin layer having a foam suppression ink-coated portion,
The raw material sheet according to claim 5, wherein the expansion suppression ink contains a resin having a glass transition temperature of 60 ° C to 120 ° C in an amount of 70% by weight or more in the resin solid content of the binder resin.   The raw material sheet according to claim 6, wherein the resin having a glass transition temperature of 60 ° C to 120 ° C is an acrylic resin.   A foamable paper container comprising the raw material sheet according to any one of claims 1 to 7.

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