WO2022014484A1 - Foam paper laminate - Google Patents

Abstract

Provided is a foam paper laminate comprising: a foam paper composed of a base paper, a thermoplastic resin layer (A) disposed on one surface of the base paper, and a foamed thermoplastic resin layer (B) disposed on the other surface of the base paper; and a printing layer disposed on the foamed thermoplastic resin layer (B), wherein the printing layer contains at least a binder resin, and the binder resin contains a urethane resin having a structural unit derived from castor oil polyol.

Description

Foam paper laminate

The embodiment of the present invention relates to a foamed paper laminate.

Effervescent containers are widely used as containers for storing foods containing high-temperature or low-temperature liquids because they have excellent heat insulating properties. In particular, foam containers are lacking in products generally called "cup noodles" that can be eaten in a few minutes by simply pouring an appropriate amount of boiling water into instant noodles such as ramen, udon, and soba noodles contained in a container. I can't. Styrofoam containers and foamed paper containers are known as foaming containers for cup noodles, but in recent years, foamed paper containers have been attracting attention from the viewpoint of environmental load and safety.

The foamed paper container is manufactured using a foamed paper material having a paper base material and a thermoplastic resin layer that foams by heating at the time of manufacturing the container to form a heat insulating layer. Usually, a printing layer including a printing pattern such as a decorative pattern, a company name, and a barcode is formed on the surface of a foamed paper container (foamed paper material). Therefore, it is desirable that the printing layer has excellent foaming followability without hindering foaming when the thermoplastic resin layer of the foamed paper material foams by heating to form a heat insulating layer. Further, the surface (printing surface) of the printed layer in the foamed paper laminate after the thermoplastic resin layer is foamed is smooth, has no cracks or swelling, and has an excellent appearance (hereinafter referred to as “foamed appearance”). It is desirable to have. Further, it is desirable that the printed surface is excellent in various resistances such as friction resistance and heat resistance required for manufacturing the container. Further, in the food field, since a solvent such as ethanol is widely used for disinfection, the printed layer is also required to have solvent resistance such as ethanol resistance.

Conventionally, gravure ink or flexo ink has been used to form a printing layer of a foamed paper container. For example, Patent Document 1 and Patent Document 2 include an ink for a foamed paper container (foam cup) containing a binder resin and a pigment as the ink forming the print layer of the foamed paper container, and the binder resin contains a urethane resin. It is disclosed.

On the other hand, in recent years, biomass resin has been attracting attention in order to build a sound material-cycle society. For example, as the film-shaped biomass resin, polylactic acid (PLA), polyethylene resin derived from a biomass raw material, or the like has been commercialized. Further, Patent Documents 3 to 5 disclose environment-friendly inks using biomass resin and laminates using the inks.

International Publication No. 2009/11800 Japanese Unexamined Patent Publication No. 2018-109131 Japanese Unexamined Patent Publication No. 2018-058955 Japanese Unexamined Patent Publication No. 2014-004799 Japanese Unexamined Patent Publication No. 2014-005414

As mentioned above, from the viewpoint of building a sound material-cycle society, it is desirable to use biomass resin using animal and plant-derived raw materials instead of the resin obtained from conventional fossil fuels in the field of foamed paper containers as well. On the other hand, the printing layer in a foamed paper container is required to have various properties such as abrasion resistance and ethanol resistance, as well as special performance such as heat resistance, foam followability, and foam appearance. Above all, the heat resistance of the printed layer during heat processing is important.

In the use of foamed paper containers, in the manufacturing of containers, the base material expands due to heat processing in the process of forming the foamed layer. Therefore, when the heat resistance of the printed layer is insufficient, troubles such as the printed layer peeling from the base material and depositing on the apparatus are likely to occur in the manufacturing process of the container. Therefore, the printed layer in the foamed paper container is required to have heat resistance that does not peel off from the base material even under the conditions of being heated and the base material expanding.

As mentioned above, in the use of foamed paper containers, the base material expands with the heat processing that forms the foamed layer. On the other hand, in general applications such as packaging, the base material is hardly deformed because the heat treatment is not performed after the print layer is formed. Due to these differences, it is desirable to simply replace the ink component for forming the print layer of the foamed paper container with the environment-friendly ink used for general purposes, such as heat resistance. It is difficult to obtain various characteristics at a sufficiently satisfactory level. Therefore, the development of a foamed paper container using a biomass resin is desired, but as described above, the adoption of a biomass resin has not progressed because the foamed paper container is required to have special performance. Therefore, in view of the above situation, the embodiment of the present invention has a printing layer containing a biomass resin, and excellent heat resistance, foaming followability, foaming appearance, and ethanol resistance can be obtained, and a foamed paper container can be obtained. Provided is a foamed paper laminate that can be suitably used as a member.

In order to solve the above problems, the present inventors have diligently studied the resin components constituting the print layer of the foamed paper laminate, and formed a print layer containing a specific biomass resin to achieve heat resistance and foaming. We have found that good results can be obtained in terms of characteristics of the printed layer such as followability, foamed appearance, and ethanol resistance, and have completed the present invention. That is, the present invention relates to the following embodiments, but includes various embodiments without limitation.

One embodiment is a foamed paper composed of a base paper, a thermoplastic resin layer (A) provided on one side of the base paper, and a foamed thermoplastic resin layer (B) provided on the other side of the base paper. , And a foamed paper laminate provided with a printing layer provided on the foamed thermoplastic resin layer (B).
The print layer contains at least a binder resin and contains
The binder resin relates to a foamed paper laminate containing a urethane resin having a structural unit derived from castor oil polyol.

In one embodiment, the urethane resin preferably further has a structural unit derived from a polyester polyol which is a condensate of a dibasic acid and a diol. The mass ratio (a1) / (a2) of the structural unit (a1) derived from castor oil polyol and the structural unit (a2) derived from polyester polyol is preferably 75/25 to 10/90.

In one embodiment, the content of the structural unit derived from the polyether polyol is preferably 8% by mass or less based on the total mass of the urethane resin.

In one embodiment, the weight average molecular weight of the castor oil polyol is preferably 1,000 to 5,000.

In one embodiment, the binder resin further contains a vinyl chloride / vinyl acetate copolymer, and the content of the vinyl chloride / vinyl acetate copolymer is 5% by mass or more and 50% by mass or less based on the total mass of the binder resin. Is preferable.

In one embodiment, the elongation rate of the binder resin is preferably 400% to 3,000%.
The disclosures of this application relate to the subject matter described in Japanese Patent Application No. 2020-12307 filed on July 17, 2020, the entire disclosure of which is incorporated herein by reference.

According to the present invention, a foamed paper laminate having a printing layer containing a biomass resin, excellent heat resistance, foaming followability, foaming appearance, and ethanol resistance can be obtained, and can be suitably used as a member of a foamed paper container. Can provide a body.

FIG. 1 is a perspective view showing a structural example of a foamed paper container provided with a foamed paper laminate according to an embodiment. FIG. 2 is a schematic cross-sectional view showing a part (reference numeral I portion) of the foamed paper container shown in FIG. 1 in an enlarged manner.

Hereinafter, embodiments of the present invention will be specifically described. However, the present invention is not limited to the embodiments described below, and includes various embodiments.

<1> Foamed Paper Laminated Material One embodiment relates to a foamed paper laminated body. The foamed paper laminate is formed on a foamed paper having a thermoplastic resin layer (A), a paper base material, and a foamed thermoplastic resin layer (B) in that order, and on the surface of the foamed thermoplastic resin layer (B) of the foamed paper. It has a formed printed layer. The printed layer preferably contains at least a biomass resin as a binder resin, and the biomass resin preferably contains at least a biomass-derived urethane resin. In one embodiment, the binder resin comprises a urethane resin having a structural unit derived from castor oil polyol. The urethane resin is a biomass-derived urethane resin obtained by using at least castor oil polyol as a polyol component as a raw material. Details of such a biomass-derived urethane resin will be described later.

In one embodiment, the foamed thermoplastic resin layer (B) has a number of foamed cells of 1000 cells / 1 cm ² or more per unit surface area, and is a printed layer after being immersed in ethanol at 25 ° C. for 30 minutes. The residual ratio is preferably 50% by mass or more.

As for the number of foamed cells per unit surface surface of the foamed thermoplastic resin layer (B) (hereinafter, also referred to as foamed layer (B)), the larger the number, the smaller the bubbles existing in the foamed layer (B), and the smaller the number. It means that the bubbles existing in the foam layer (B) are large. When the bubbles existing in the foam layer (B) become large, appearance defects such as cracks and swelling of the printed surface are likely to occur.

In one embodiment, the number of foamed cells per unit surface area of the foamed layer (B) ^{is preferably 1000 cells / 1 cm 2} or more, and more preferably 1250 cells / 1 cm ² or more. When the number of foamed cells is in the above range, an excellent foamed appearance without cracks and swelling can be easily obtained in the printed layer formed on the foamed layer (B). On the other hand, the upper limit of the number of foamed cells is not particularly limited. In one embodiment, the number of foamed cells may be 1600 cells / cm ² or less from the viewpoint of manufacturing conditions and the like.

Here, the "number of foamed cells per unit area" is an independent cell (air bubble) existing in a range partitioned by a certain length in the vertical and horizontal (XY) directions on the surface of the foamed layer (B). It means a value calculated as the number of independent cells per ^{1 cm 2} by counting the number of. The number of independent cells is determined by removing the printed layer of the foamed paper laminate with a solvent, exposing the surface of the foamed layer (B), and then observing the surface of the foamed layer (B) using an optical microscope. To.

The thickness of the foam layer (B) is preferably 500 μm or more, more preferably 630 μm or more, from the viewpoint of heat insulating properties. If the thickness of the foamed layer (B) is 500 μm or more, the foamed paper laminate is formed into a cup-shaped container, and even when hot water of about 100 ° C. is poured into the container, the container is continuously held with bare hands. It becomes easy to hold in. On the other hand, from the viewpoint of resource saving, it is preferable that the amount of resin used is as small as possible. Further, from the viewpoint of heat insulating properties, the heat insulating layer does not need to be thick enough to have excessive quality. Therefore, the thickness of the foamed layer (B) is preferably 950 μm or less, more preferably 900 μm or less, and extremely preferably 800 μm or less.

From the above viewpoint, in one embodiment, the thickness of the foam layer (B) is preferably 500 to 950 μm, more preferably 500 to 900 μm, and even more preferably 500 to 800 μm. The thickness of the foamed layer (B) is determined by observing the cross section of the foamed paper laminate with an optical micrograph and measuring the height from the upper surface of the paper substrate to the lower surface of the printed layer.

In the foamed paper laminate of the above embodiment, the foamed layer (B) of the foamed paper means a state after the thermoplastic resin layer is foamed by heating. That is, the foamed layer (B) is formed by heating and foaming an unexpanded thermoplastic resin layer (foamed thermoplastic resin layer forming layer (B _{0)) as a precursor.} In one embodiment, in order to form the foamed paper laminate, it has a thermoplastic resin layer (A), a paper substrate, and a melting point lower than that of the thermoplastic resin layer (A), and is foamed by heat treatment. A foamed paper material (foamed paper before heating) having a foamed thermoplastic resin layer forming layer (B _{0) in sequence can be used.} The foamed paper material can be made of a material known in the art. Hereinafter, the constituent materials of the foamed paper laminate will be specifically described.

(Paper base material)
The paper base material constituting the foamed paper laminate is not particularly limited. For example, kraft paper or woodfree paper can be used. From the viewpoint of achieving sufficient toughness when used as a container, the basis weight of the paper substrate ^{is preferably 150 to 450 g / m 2} , and more preferably 250 to 400 g / m ² . Further, from the viewpoint of obtaining suitable foamability of a thermoplastic resin such as polyethylene, the water content contained in the paper substrate is preferably 4 to 10% by mass, more preferably 5 to 8% by mass.

(Thermoplastic resin layer, foam layer forming layer)
In one embodiment, the thermoplastic resin layer (A) and the foamed thermoplastic resin layer forming layer (B ₀ ) (hereinafter, also referred to as the foamed layer forming layer (B ₀ )) are conventionally known as container materials. It may be a film made of a resin material. For example, a film (thermoplastic resin film) made of at least one thermoplastic resin selected from the group consisting of stretched and unstretched polyolefins such as polyethylene and polypropylene, polyester, nylon, cellophane, and vinylon can be used. can. In one embodiment, a polyethylene film can be preferably used because it is excellent in laminating suitability and foamability. Further, from the viewpoint of reducing the environmental load, it is preferable that at least one of the thermoplastic resin layer (A) and the foamed layer forming layer (B ₀ ) is a film composed of a polyethylene resin derived from biomass.

The foamed paper material can be constructed by laminating thermoplastic resin films having different melting points on a paper base material. Here, the melting point of the thermoplastic resin film provided on the other surface of the paper substrate as _{the foam layer forming layer (B 0} ) rather than the thermoplastic resin film provided on one surface of the paper substrate as the thermoplastic resin layer (A). Select the material so that (Mp) is low. In the foamed paper material, the water content in the paper substrate evaporates during the heat treatment, and the evaporated water content is _{extruded to the softened foam layer forming layer (B 0} ) (low Mp resin film) side. Then, with such extrusion, the low Mp resin film swells (foams) toward the outside, and a foamed layer (B) is formed. The foam layer (B) thus formed functions as a heat insulating layer in the container. On the other hand, for the thermoplastic resin layer (A) (high Mp resin film), a material that does not melt or soften when the low Mp resin film foams by heat treatment is selected.

From the viewpoint of producing a foam paper container using a foam paper laminate, the foam paper material is, for example, a high Mp polyethylene film having a melting point of about 125 ° C. to 140 ° C. on one surface (inside of the container) of a paper base material. _{(Thermoplastic resin layer (A)) and a low Mp polyethylene film (foam layer forming layer (B 0} )) having a melting point of about 105 ° C. to 120 ° C. on the other surface (outside of the container) of the paper substrate, respectively. It may have a laminated structure. The low Mp polyethylene film foams to form a foamed layer by heating during the production of a foamed paper container or the like. On the other hand, the high Mp polyethylene film preferably functions as a coating layer. That is, the coating layer can suppress the evaporation of the water content in the paper base material to the outside during the foaming of the low Mp polyethylene film, and can efficiently contribute the water content in the paper base material to the foaming.

In one embodiment, the material of the foam layer forming layer (B ₀ ) preferably contains a low density polyethylene resin (density 910 to 925 kg / m ³ , melting point 105 to 120 ° C.) among the polyethylene resins. The density of the low-density polyethylene resin is more preferably 910 to 922 kg / m ³ , and even more preferably 910 to 918 kg / m ³ . As the material of the foam layer forming layer (B ₀ ), a medium density polyethylene resin (density 925 to 940 kg / m ³ , melting point 115 to 130 ° C.) and a high density polyethylene resin (density 940 to 970 kg / m ³ , melting point 125 to 140). When ° C) is used, the melting point is high and it tends to be difficult to obtain sufficient foamability. Further, from the viewpoint of obtaining a uniformly foamed layer, the melt flow rate of the polyethylene resin (hereinafter referred to as “MFR”) is preferably 8 to 28 g / 10 minutes, and preferably 10 to 20 g / 10 minutes. More preferred.
In one embodiment, it is preferable to combine a polyethylene film derived from biomass. ^{For example, "SHE150 (density 948 kg / m 3} , MFR 1 g / 10 minutes)" manufactured by Braskem Co., Ltd. is used as the thermoplastic resin layer (A), and Braskem Co., Ltd. _{is used as the material for the foam layer forming layer (B 0).} "SBC818 (density 918 kg / m ³ , MFR 8.1 g / 10 minutes)" can be used.

Although not particularly limited, in one embodiment, _{the film thickness of the foamed layer forming layer (B 0} ) is preferably 40 μm or more, and more preferably 60 μm or more. By adjusting the film thickness to 40 μm or more, sufficient heat insulating properties can be obtained after the heat treatment.

On the other hand, from the viewpoint of resource saving, it is preferable that the amount of resin used is as small as possible. Also, from the viewpoint of heat insulating properties, it is not necessary to have a thickness sufficient for excessive quality. Therefore, the film thickness of the foam layer forming layer (B ₀ ) is preferably 150 μm or less, more preferably 100 μm or less, and extremely preferably 80 μm or less.

(Print layer)
In the foamed paper laminate of the above embodiment, the printing layer is a coating film obtained by applying an ink composition to the surface of _{the foamed layer forming layer (B 0) of the foamed paper material.} The main component of the coating film constituting the printing layer (that is, the ink composition) is a binder resin, and the binder resin is characterized by containing at least a urethane resin having a structural unit derived from castor oil polyol. By using such a biomass-derived urethane resin, it is excellent in heat resistance and foaming followability during heat processing, as well as foaming appearance and ethanol resistance, and can be suitably used as a member of a foamed paper container. The body can be realized.

In one embodiment, the thickness of the printed layer (coating film after drying) is preferably 0.5 to 5.0 μm from the viewpoint of foaming suppressing power by the printed layer and abrasion resistance. The thickness of the printed layer may be more preferably 0.5 to 4.0 μm, still more preferably 0.5 to 3.5 μm.

In the above embodiment, since the urethane resin derived from biomass is used as the binder resin constituting the print layer, the environmental load can be reduced as compared with the case where the conventional resin derived from petroleum is used. From such a viewpoint, the biomass degree based on the total mass of the binder resin is preferably 10% by mass or more. In other embodiments, the print layer may contain a colorant and a binder resin. In this case, the biomass content of the colorant and the binder resin in a total of 100 parts by mass is preferably 10% by mass or more. From the viewpoint of building a sound material-cycle society, the higher the biomass level, the more preferable. Specifically, the biomass degree is more preferably 15% by mass or more.

As used herein, the term "biomass degree" means the proportion of biomass-derived raw materials in all the components used as raw materials. For example, it means the ratio of the components derived from biomass in the compound obtained after the synthesis of the binder resin. That is, among the components derived from biomass, if the raw materials are all derived from biomass such as vegetable oil, the degree of biomass is 100%. On the other hand, in the case of a compound obtained by reacting a raw material derived from biomass with a raw material not derived from biomass (for example, derived from petroleum) at a constant ratio, the ratio of the raw material derived from biomass in the compound is the degree of biomass. In this case, the biomass degree can be calculated by converting it into the raw material mass before the reaction, and is a value represented by the following formula (1).
Formula (1): Biomass degree = 100 × total mass of biomass-derived components in the compound / total mass of the compound

More specifically, for example, in the case of a urethane resin which is a reaction product of a biomass-derived polyol (biomass degree A%) and petroleum-derived diisocyanate, the biomass degree is expressed by the following formula.
Degree of biomass = 100 x (mass of polyol derived from biomass x A%) / mass of urethane resin In the above formula, "mass of urethane resin" is the sum of polyol derived from biomass and diisocyanate derived from petroleum, and is ". The "polyol derived from biomass" is the total of all the polyols derived from biomass used in the urethane resin.

In the foamed paper laminate of the above embodiment, at least castor oil polyol is used as the polyol component, so that it is easy to increase the degree of biomass. The degree of biomass can also be determined by measuring the concentration ^{of radioactive carbon (14} C) in the compound using accelerator mass spectrometry or the like. Since no radioactive carbon is present in petroleum-derived compounds, biomass-derived compounds can also be distinguished from petroleum-derived compounds by the degree of biomass.

<2> Ink Composition One embodiment relates to an ink composition that can be suitably used for forming a print layer of the foamed paper laminate of the above embodiment. The ink composition contains a binder resin containing a urethane resin having a structural unit derived from castor oil polyol, and a solvent. In other embodiments, the ink composition may further comprise a colorant such as a pigment. The ink composition may further contain various additives in addition to the above components, if necessary. Hereinafter, the composition of the ink composition will be described.

(Binder resin)
At the time of heat processing for forming the foam layer (B), it is preferable that the printed layer does not inhibit the foaming of the _{foam layer forming layer (B 0) and has excellent foam followability.} On the other hand, in order to suppress foaming appearance defects such as cracks and fire swelling on the printed surface, _{it is preferable that the foaming of the foam layer forming layer (B 0} ) can be appropriately controlled by the printed layer. On the other hand, since the binder resin is the main component of the printing layer (coating film), it is possible to satisfactorily adjust the foaming followability and foaming suppressing power of the printed layer by selecting an appropriate binder resin form. can.

The binder resin preferably has an elongation rate of 50 to 4,000%, and more preferably 400 to 3,000%, from the viewpoint of foaming followability. On the other hand, if the stress is too small even if the elongation rate of the binder resin is 50 to 4,000%, the printed layer follows the foaming, but the foaming cannot be properly controlled, and cracks and swelling occur. It occurs and the foaming appearance tends to deteriorate. Therefore, from the viewpoint of achieving both foaming followability and foaming appearance on the printed surface, the binder resin preferably has an elongation rate of 50 to 4,000% and a stress of 0.1 mPa or more.

The term "elongation rate" described in the present specification refers to a sample having dimensions of 0.3 mm in thickness and 15 mm in width, using a small tensile tester manufactured by Intesco, with a tensile speed of 100 mm / min and a room temperature of 25. It means the value obtained by measuring at ° C.

In one embodiment, the binder resin preferably has a stress of 0.1 mPa or more, more preferably 1 mPa or more, and even more preferably 5 mPa or more at an elongation rate of 50 to 4,000%. On the other hand, the stress at an elongation rate of 50 to 4,000% is preferably 50 mPa or less, more preferably 40 mPa or less, and even more preferably 30 mPa or less. The stress at an elongation rate of 50 to 4,000% of the binder resin containing the urethane resin may be 0.1 mPa to 50 mPa.

When the binder resin has an elongation rate and stress in the above range, it becomes easy to obtain good results in terms of foaming appearance in addition to foaming followability. Further, a binder resin having an elongation rate and stress in the above range is preferable from the viewpoint of enhancing ethanol resistance because it is easy to obtain a desired residual rate of the printed layer.

(Urethane resin)
As described above, the binder resin preferably contains at least a urethane resin from the viewpoint of foaming followability of the printed layer during foaming. Specific embodiments include urethane resins obtained by reacting a polyol with diisocyanate. Further, a urethane urea resin obtained by extending a chain of a urethane prepolymer obtained by reacting a polyisocyanate with a polyol with an amine compound can be mentioned. That is, the urethane resin is a resin having a urethane bond, but even if it has a urea bond or the like, it is included in the concept.

When a urethane resin is used, it is excellent in various resistances such as light resistance, heat resistance, abrasion resistance, and blocking resistance, and is resistant to a low Mp resin film (foam layer forming layer (B ₀ )) which is a base material at the time of printing. An ink composition capable of forming a print layer having excellent adhesiveness can be easily formed. Further, by using the urethane resin, even when the ink composition is stored for a long period of time in an environment where heat or light is applied, the friction resistance and blocking resistance of the print layer and the low Mp resin film as a base material are used. Good results can also be obtained in various properties such as adhesiveness to the resin.

The urethane resin preferably has a weight average molecular weight in the range of 10,000 to 100,000. More preferably, it is 30,000 to 80,000. When the weight average molecular weight is within the above range, the blocking resistance of the printed layer, the solubility in an organic solvent, and the dispersibility of the pigment can be easily improved.

The urethane resin preferably has an amine value. The amine value is preferably 0.5 to 40 mgKOH / g, more preferably 1 to 30 mgKOH / g, and even more preferably 3 to 20 mgKOH / g. When the amine value is within the above range, it becomes easy to improve the adhesion.

In one embodiment, the urethane resin preferably has a glass transition temperature (Tg) of −100 ° C. to 0 ° C. The Tg of the urethane resin may be more preferably −10 ° C. or lower, still more preferably −25 ° C. or lower. When the Tg of the binder resin is within the above range, excellent foaming followability can be obtained during the heat treatment of the foamed paper material, and deterioration of the heat insulating property can be suppressed. In addition, it is possible to suppress foaming appearance defects such as cracks and swelling on the printed surface. The Tg may be −100 ° C. or higher, preferably −90 ° C. or higher, more preferably −80 ° C. or higher, and even more preferably −60 ° C. or higher. A binder resin having a Tg in the above range is preferable from the viewpoint of ethanol resistance because it is easy to obtain a desired residual ratio of the printed layer.

(Urethane resin having a structural unit (a1) derived from castor oil polyol)
In the embodiment of the present invention, the urethane resin is characterized by using a urethane resin derived from biomass, and includes a urethane resin having at least a structural unit (a1) derived from castor oil polyol. Specific embodiments include urethane resins obtained by reacting a polyol containing a castor oil polyol with a diisocyanate. Further, a preferred embodiment is a urethane urea resin obtained by extending a chain of a urethane prepolymer obtained by reacting a polyisocyanate with a polyol containing a castor oil polyol with an amine compound.

As the diisocyanate, known aromatic, aliphatic or alicyclic diisocyanates can be used. For example, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzylisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3- Phenylene diisocyanate, 1,4-phenylenedi isocyanate, 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 (isocyanatemethyl) cyclohexane, methylcyclohexane diisocyanate, norbornan diisocyanate, m-tetramethylxylylene diisocyanate and dimer acid Isocyanate diisocyanate obtained by converting the carboxyl group of the above into an isocyanate group. In one embodiment, isophorone diisocyanate is preferred.

As the polyol, it is essential to use castor oil polyol, but other than that, polyester polyol, polyether polyol, low molecular weight polyhydric alcohol, polycarbonate polyol and the like can be used. However, all polyols do not correspond to castor oil polyols. Hereinafter, the polyol component will be described more specifically.
(Castor oil polyol)
The castor oil polyol may have a structural unit derived from ricinoleic acid (hereinafter, castor oil fatty acid) which is a component of castor oil. A form in which the structural unit derived from ricinoleic acid is the main component in the total amount of castor oil polyol (50% by mass or more in the total amount of castor oil polyol) is preferable. The structure is not particularly limited as long as the average number of functional groups of the hydroxyl group is 1 to 3, and examples thereof include castor oil and dehydrated castor oil. In addition, castor oil fatty acid condensate obtained by condensing castor oil fatty acid with a polyol such as diol as an initiator, and hydrides thereof and the like can be mentioned. These castor oil polyols can be used alone or in admixture of two or more.

The urethane resin preferably contains a structural unit derived from castor oil polyol in an amount of 10 to 80% by mass, more preferably 15 to 60% by mass, and more preferably 15 to 40% by mass, based on the resin solid content of the urethane resin. It is more preferable to contain it. When the content of the structural unit derived from the castor oil polyol is within the above range, it is easy to maintain or improve the dispersion stability of the colorant, the heat resistance of the printed layer, and the blocking resistance.

The molecular weight of the castor oil polyol is preferably 500 to 6,000, more preferably 1,000 to 5,000, still more preferably 1,500 to 4,000, and 1,500 to 3,500. The range of is particularly preferable. When the weight average molecular weight is within the above range, it is easy to obtain excellent _{film strength and excellent adhesion to the foam layer forming layer (B 0) when the foamed paper laminate is formed.} Become.

(Polyester polyol)
The urethane resin preferably contains a structural unit derived from a polyester polyol in addition to a structural unit derived from a castor oil polyol. In the study by the present inventors, when the urethane resin obtained by using the castor oil polyol and the polyester polyol in combination is used as the binder resin of the printing layer, it is more than the case where the urethane resin obtained by using only the castor oil polyol is used alone. It was found that excellent foamed appearance and heat resistance tend to be obtained.

The polyester polyol is not limited to the following examples, but for example, adipic acid, phthalic anhydride, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, pimelic acid, and azelaic acid. , Sevacinic acid, suberic acid, glutaric acid, 1,4-cyclohexyldicarboxylic acid, etc., and ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol. , 1,3-Butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-1, 3-Propanediol, 3,3,5-trimethylpentanediol, 2,4-diethyl-15-pentanediol, 1,12-octadecandiol, 1,2-alkanediol, 1,3-alkanediol, 1-monoglyceride , 2-Monoglyceride, 1-monoglycerin ether, 2-monoglycerin ether, etc., a condensate obtained by esterification reaction with a diol, a caprolactone polymer obtained by using the diol of the present invention as an initiator, a valerolactone polymer, Examples thereof include polyesterdiols such as methylvalerolactone polymers and lactic acid polymers. These polyester polyols can be used alone or in admixture of two or more.

The amount of the polyester polyol used is such that the structural unit derived from the polyester polyol is contained in an amount of 15 to 80% by mass with respect to the resin solid content of the urethane resin from the viewpoint of heat resistance, film strength, and blocking resistance in the laminated body. It is preferable, more preferably 25 to 75% by mass.

In one embodiment, the urethane resin preferably has a structural unit derived from a polyester polyol in addition to a structural unit derived from a castor oil polyol. The polyester polyol is a condensate of the dibasic acid and the diol, and the mass ratio (a1) / (a2) of the structural unit (a1) derived from the castor oil polyol and the structural unit (a2) derived from the polyester polyol is , 75/25 to 10/90, more preferably 60/40 to 25/75, and even more preferably 50/50 to 25/75. By adjusting the mass ratio in this way, foaming followability, heat resistance, and ethanol resistance can be easily improved.

In one embodiment, the binder resin contains a urethane resin obtained by using only castor oil polyol as a polyol component. In another embodiment, the binder resin contains a urethane resin obtained by using a castor oil polyol and a polyester polyol in combination as a polyol component. In still another embodiment, the binder component may contain the urethane resin of the above embodiment and the urethane resin obtained by using only the polyester polyol as the polyol component. However, when a polyester polyol is used as the polyol component, it is more preferable that the structural unit derived from castor oil polyol and the structural unit derived from polyester polyol coexist in one polymer chain from the viewpoint of ink stability and the like. ..

(Polyether polyol)
In one embodiment, the urethane resin may have a structural unit derived from a polyether polyol. The polyether polyol is not particularly limited, and examples thereof include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene glycol, and copolymerized polyetherdiols thereof. These polyether polyols can be used alone or in admixture of two or more.

By introducing a structural unit derived from a polyether polyol into a urethane resin, it is possible to adjust various physical properties required for a resin for printing ink, such as pigment dispersibility, resin viscosity, and solubility in an organic solvent. On the other hand, in the study by the present inventors, it has been found that if the number of structural units derived from the polyether polyol is too large, the heat resistance, which is an essential property for the printed layer of the foamed paper laminate, is lowered. From such a viewpoint, in one embodiment, the content of the structural unit derived from the polyether polyol is preferably 8% by mass or less, preferably 5% by mass or less, based on the total mass of the urethane resin. It is more preferably 2% by mass or less, and may be 0% by mass. From the viewpoint of improving the heat resistance of the printed layer, it is extremely preferable that the urethane resin does not contain structural units derived from the polyether polyol.

(Small molecule polyhydric alcohol)
In one embodiment, the urethane resin may have a structural unit derived from a small molecule polyhydric alcohol. By introducing a structural unit derived from a low molecular weight polyhydric alcohol, various physical properties required for a resin for printing ink such as pigment dispersibility, resin viscosity, solubility in an organic solvent, and blocking resistance can be adjusted.

The low molecular weight polyhydric alcohol is not limited to the following examples, and examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, and cyclohexanedimethanol. Glycerin, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, hydrogenated bisphenol A, tri Examples thereof include methylolpropane, glycerin, pentaerythritol, and sorbitol. These small molecule polyhydric alcohols are used for the purpose of adjusting the molecular weight of the ink composition of the present invention and the distribution of hard segments and soft segments. These small molecule polyhydric alcohols can be used alone or in admixture of two or more.

(Amine compound)
The amine compound functions as a chain extender for the urethane prepolymer and imparts a urea bond to the urethane resin. Examples of the amine compound include polyamines and amino alcohols. The chain extender can be used alone or in combination of two or more.

Examples of polyamines include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, and dimerdiamine obtained by converting the carboxyl group of dimer acid into an amino group. In addition, N- (2-hydroxyethyl) ethylenediamine, N- (2-hydroxyethyl) propylenediamine, N- (2-hydroxypropyl) ethylenediamine, N- (2-hydroxypropyl) propylenediamine, N, N'-bis (2-Hydroxyethyl ethylenediamine, N, N'-bis (2-hydroxyethyl) propylene diamine, N, N'-bis (2-hydroxypropyl) ethylenediamine, N, N'-bis (2-hydroxypropyl) propylene diamine Examples thereof include amines having a hydroxyl group in the molecule, methyliminobispropylamine, lauryliminobispropylamine and the like having a tertiary amino group in the molecule.

Examples of amino alcohols include N, N-dimethylethanolamine, N, N-dimethylethanolamine, N, N-dibutylethanolamine, N- (β-aminoethyl) ethanolamine, N-methylethanolamine, and N-methyl. Diethanolamine, N-ethylethanolamine, N-ethyldiethanolamine, Nn-butylethanolamine, Nt-butyldiethanolamine, Nt-butyldiethanolamine, N- (β-aminoethyl) isopropanolamine, N, N- Examples thereof include diethylisopropanolamine.

(Reaction solvent)
For the production of the urethane resin, an organic solvent having no alcohol and / or a hydroxyl group, which is a medium described later, can be used.

Examples of alcohols include aliphatic alcohols having 1 to 7 carbon atoms such as methanol, ethanol, normal propanol, isopropanol, normal butanol, isobutanol, tertiary butanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol mono. Examples thereof include glycol monoethers such as propyl ether, propylene glycol monoisopropyl ether and propylene glycol monobutyl ether.
When producing a prepolymer solution containing an isocyanate group, a tertiary alcohol having low reactivity is preferable from the viewpoint of reactivity with the isocyanate group, and examples thereof include tertiary butanol.

Examples of the organic solvent having no hydroxyl group include esters such as ethyl acetate, butyl acetate and cellosolve acetate, ketones such as acetone, methyl ethyl ketone, isobutyl ketone and cyclohexanone, cyclic ethers such as tetrahydrofuran and dioxane, toluene and xylene and the like. Examples thereof include aromatic hydrocarbons, halogenated hydrocarbons such as methylene chloride and ethylene chloride, dimethylsulfoxide and dimethylsulfamide. Two or more kinds of these reaction solvents may be mixed and used.

(Manufacturing of urethane resin)
The method for producing the urethane resin is not particularly limited, and the urethane resin can be produced by a general chain extension reaction.
For example, a castor oil polyol, a polyol other than castor oil polyol, and a diisocyanate are reacted under a solvent-free environment or an organic solvent having no hydroxyl group to produce an isocyanate group-containing prepolymer. Here, the above reaction is carried out at an equivalent ratio in which the isocyanate group of the diisocyanate is excessive with respect to the hydroxyl groups of the castor oil polyol and the polyol other than the castor oil polyol. The isocyanate group-containing prepolymer obtained as described above is dissolved in an organic solvent having no hydroxyl group and / or a tertiary alcohol having low reactivity with the isocyanate group to obtain a prepolymer solution. Next, there is a method in which the previously prepared isocyanate group-containing prepolymer solution is added to the chain extender dissolved in a solvent to cause a chain extension reaction.

The solvent used to dissolve the chain extender may be the same as the organic solvent used in the production of the prepolymer. When alcohol is used as the solvent, diamines and amino alcohols are preferably used as the chain extender from the viewpoint of reactivity with the isocyanate group-containing prepolymer.

In the production of urethane resin, the ratio of sardine oil polyol, polyol other than sardine oil polyol, and diisocyanate is the ratio of the number of moles of isocyanate groups of diisocyanate to the number of moles of hydroxyl groups of sardine oil polyols and polyols other than sardine oil polyols. It is preferable to adjust the NCO / OH ratio so as to be in the range of 1.1 to 3.0. When the NCO / OH ratio is within the above range, it is easy to maintain or improve the blocking resistance and the adhesion to the substrate.

The above embodiment is characterized by containing a urethane resin as a constituent component of the print layer, but does not exclude the combined use of a binder resin other than the urethane resin. Specific examples thereof are acrylic resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride / vinyl acetate copolymer, nitrocellulose and the like.

Among them, the combined use of urethane resin and vinyl chloride / vinyl acetate copolymer and / or nitrocellulose is preferable. As described above, when the binder resin further contains a vinyl chloride / vinyl acetate copolymer, it is preferable to contain 50% by mass or more of the urethane resin based on the total mass of the binder resin. The content is more preferably 70% by mass or more, further preferably 85% by mass or more. The mass ratio of the urethane resin containing the urethane resin to the vinyl chloride / vinyl acetate copolymer is preferably 40:60 to 95: 5, and more preferably 55:45 to 90:10. , 70:30 to 90:10 is extremely preferable. By adjusting the mass ratio of both within the above range, the foam paper followability and heat resistance can be easily improved.

(Colorant)
In one embodiment, the ink composition may further comprise a colorant. As the colorant, for example, those used in ordinary ink compositions such as organic pigments, inorganic pigments, and dyes may be used. C.I. I. Pigments can be preferably used.

Examples of organic pigments include azo-based, phthalocyanine-based, anthraquinone-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethine-azo-based, dictopyrrolopyrrole-based, and isoindoline-based. Etc. are preferably mentioned.

Examples of the inorganic pigment include carbon black, aluminum powder, bronze powder, chrome vermillion, chrome yellow, cadmium yellow, cadmium red, ultramarine, navy blue, red iron oxide, yellow iron oxide, iron black, titanium oxide, zinc oxide and the like. Be done.

Examples of the dye include tartradin lake, Rhodan 6G lake, Victoria pure blue lake, alkaline blue G toner, brilliant green lake, and the like, and coal tar and the like can also be used. Above all, it is preferable to use an organic pigment or an inorganic pigment from the viewpoint of water resistance and the like.

The colorant is not particularly limited, and may be an amount sufficient to secure the concentration and coloring power of the ink composition. For example, the content of the colorant is generally 0.5 to 50% by mass with respect to the total mass of the ink composition. In addition, the colorant can be used alone or in combination of two or more.

In one embodiment, when a white ink composition is prepared, the blending amount of the white pigment is preferably in the range of 20 to 50% by mass based on the total mass of the ink composition. From the viewpoint of hiding power, pigment concentration, and light resistance, it is preferable to use titanium dioxide as the white pigment. On the other hand, when preparing a colored ink composition, a colored organic pigment and a colored inorganic pigment such as red iron oxide, prussian blue, ultramarine, carbon black, and graphite can be appropriately selected and used. Organic pigments are preferable from the viewpoint of color development and light resistance. The blending amount of the colored pigment is preferably in the range of 5 to 30% by mass based on the total mass of the ink composition.

(Organic solvent as an ink medium)
In one embodiment, the ink composition comprises an organic solvent as a liquid medium. Examples of the organic solvent used include, but are not limited to, aromatic organic solvents such as toluene and xylene, ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone, ethyl acetate, n-propyl acetate and isopropyl acetate. Known organic solvents such as isobutyl acetate, ester organic solvent, methanol, ethanol, n-propanol, isopropanol, n-butanol and other alcohol-based organic solvents, ethylene glycol monopropyl ether and propylene glycol monotyl ether and other glycol ether-based solvents. Can be used, and may be mixed and used. Of these, an organic solvent (non-toluene-based organic solvent) that does not contain aromatic organic solvents such as toluene and xylene is more preferable. Further, the compatibility between the urethane resin and the vinyl chloride copolymer resin, the organic solvent containing the ester-based organic solvent and the alcohol-based organic solvent is preferable, and the mass ratio (ester-based organic solvent) / (alcohol-based organic solvent) of these is 90. It is preferably / 10 to 40/60. The gravure ink may contain water as a liquid medium, but the content thereof is preferably 0.1 to 5% by mass in 100% by mass of the liquid medium.

(Additive)
The ink layer and the ink composition may contain additives such as pigment derivatives, dispersants, wetting agents, adhesion aids, leveling agents, defoaming agents, antistatic agents, viscosity modifiers, chelate crosslinkers, as required. A trapping agent, an antiblocking agent, a wax component, an isocyanate-based curing agent, a silane coupling agent, or the like can be used.

<Manufacturing method of ink composition>
The ink composition can be produced by a known method, for example, the method described in International Publication No. 2009/11800 pamphlet can be used. More specifically, a urethane resin, a vinyl chloride / vinyl acetate copolymer, and an organic solvent having a mass ratio (ester-based organic solvent) / (alcohol-based organic solvent) of 90/10 to 40/60 are sand milled. Dispersion treatment is performed with another bead mill for about 5 to 60 minutes, and a urethane resin, the above-mentioned organic solvent, a leveling agent and other additives are further added to the obtained dispersion, and the mixture is uniformly stirred to obtain an ink composition. be able to.

<3> Method for manufacturing a foamed paper laminate One embodiment relates to a method for manufacturing a foamed paper laminate. That is, one embodiment includes a foam paper having a thermoplastic resin layer (A), a paper base material, and a foam layer (B) in that order, and a printing layer formed on the surface of the foam layer (B) of the foam paper. The present invention relates to a method for producing a foamed paper laminate having the above. More preferably, in the configuration of the foamed paper laminate, the number of foamed cells per unit surface area of the foamed layer (B) is 1000 cells / 1 cm ² or more, and printing is performed after immersion in ethanol at 25 ° C. for 30 minutes. The present invention relates to a method for producing a foamed paper laminate having a layer residual ratio of 50% by mass or more.

The method for producing the foamed paper laminate is described in the following steps (i) to (iv), that is, (i) the thermoplastic resin layer (A), the paper substrate, and the melting point lower than that of the thermoplastic resin layer (A). To prepare a foamed paper material having, sequentially having a foamed layer forming layer (B _{0), which foams by heating.}
(Ii) Preparing an ink composition containing a binder resin containing a urethane resin and a medium.
(iii) Applying the ink composition to the surface of the foam layer forming layer (B _{0) of the foam paper material to form a print layer.}
(iv) The foamed paper material having the printed layer is heated to foam the foamed layer forming layer (B ₀ ) of the foamed paper material to form the foamed layer (B).

In the above manufacturing method, each step relating to (i) preparation of foamed paper material, (ii) preparation of ink composition, (iii) formation of printing layer, and (iv) formation of foamed layer (B) by heating is the same. It can be carried out according to a method well known in the technical field. Hereinafter, each step will be described.

(Step (i): Preparation of foam paper material)
(I) The preparation of the foamed paper material can be carried out, for example, according to the extrusion laminating method. The constituent materials of the paper base material, the thermoplastic resin layer (A), and the foamed layer forming layer (B ₀ ) constituting the foamed paper material are as described above. As the extrusion laminating method, a well-known method such as a single laminating method, a tandem laminating method, a sandwich laminating method, and a coextrusion laminating method can be appropriately selected. In one embodiment, polyethylene resins having different melting points can be preferably used as the constituent materials of the thermoplastic resin layer (A) and the foamed layer forming layer (B _0).

The foam layer forming layer (B ₀ ) is formed by using a polyethylene resin (low Mp polyethylene resin) having an Mp lower than the melting point (Mp) of the polyethylene resin constituting the thermoplastic resin layer (A). For the foamed paper material, a low Mp polyethylene resin is extruded into a film on one side of the paper substrate and a high Mp polyethylene resin is extruded into a film on the other surface of the paper substrate through a T-die extruder. Can be manufactured by.

The temperature of the polyethylene resin at the time of laminating (the temperature immediately below the T die) is preferably 300 to 350 ° C, more preferably 320 ° C to 340 ° C. Within this temperature range, sufficient lamination strength can be realized between each polyethylene resin layer (A, B _{0) and the paper substrate.} It is preferable to control the surface temperature of the cooling roll that passes after laminating in the range of 10 to 50 ° C.

In one embodiment, the laminating speed is preferably 50 to 130 m / min, more preferably 60 to 110 m / min. If the laminating speed is too slow, the productivity will be low, while if the laminating speed is too fast, the neck-in tends to reduce the yield. Neck-in is a phenomenon in which the width of the extruded polyethylene resin film is smaller than the effective width of the T-die when the polyethylene resin is extruded into a film by a T-die extruder. At this time, both ends of the film are thicker than the central portion. When the thickness of both ends deviates from the standard, it is common to cut and remove both ends, but when the neck-in is severe, the area deviating from the standard increases and the yield decreases.

In one embodiment, the air gap is preferably 300 mm or less, more preferably 200 mm or less. If the air gap is widened too much, the polyethylene resin will neck in and the yield will tend to decrease. The air gap refers to the distance from the T-die extrusion port to the nip roll. It is preferable to surface-treat the polyethylene resin with ozone gas and / or oxygen gas while the polyethylene resin passes through the air gap. By performing the surface treatment using ozone gas and / or oxygen gas, the formation of an oxide film can be promoted and the adhesive force with the base material layer can be improved. The amount of ozone gas and / or oxygen gas to be treated is not particularly limited, but 0.5 mg / m ² or more is preferable from the viewpoint of promoting the oxidation of the polyethylene resin.

(Step (ii): Preparation of ink composition)
The specific composition, production, and the like of the ink composition are as described above in the embodiment of the ink composition.
In one embodiment, it is preferable to prepare an ink composition containing a binder resin containing a urethane resin and a medium as the ink composition. Here, the binder resin is characterized by being a urethane resin produced by using at least castor oil polyol as a polyol component. Such a biomass-derived urethane resin preferably has a stress of 0.1 mPa to 50 mPa at an elongation rate of 50 to 4,000%.

(Step (iii): Formation of print layer)
The formation of the print layer (iii) is not particularly limited, and a well-known technique can be applied. For example, when a white ink composition is printed on the entire surface of the foam layer forming layer (B ₀ ) (low Mp resin film) as the base layer, a coater such as a bar coater, a roll coater, or a reverse roll coater may be used. In addition, various printing methods can be applied.

Among various printing methods, it is preferable to apply a printing method by gravure printing or flexographic printing. When forming the print layer by these printing methods, the ink composition of the embodiment described above can be preferably used.

In one embodiment, the print layer preferably comprises a plurality of layers. The print layer may have a base layer that covers the entire surface of the foam layer forming layer (B ₀ ) and a print pattern provided on at least a part of the surface of the base layer. For example, the base layer is composed of a white ink composition and the print pattern is formed of a color ink composition.

In one embodiment, the thickness of the printed layer is preferably adjusted so that the film thickness of the dry coating film is 0.5 to 5 μm from the viewpoint of the foaming suppressing force of the printed layer and the friction resistance. .. The film thickness of the printed layer (dry coating film) may be more preferably 0.5 to 4 μm, still more preferably 0.5 to 3.5 μm. Here, when the print layer is composed of a plurality of layers, it is preferable to adjust the film thickness of the print layer so that the thickness of the entire print layer is within the above range.

In another embodiment, the print layer may include a plurality of layers and may have a transparent layer as the outermost layer thereof. The lucidum can be configured using a pigment-free clear ink composition.

(Step (iv): Formation of foam layer (B))
In the formation of the foamed layer (B) by the above (iv) heating, the appropriate heating temperature and heating time vary depending on the characteristics of the paper substrate used and the thermoplastic resin film. A person skilled in the art can determine the combination conditions of the optimum heating temperature and heating time according to the material such as the thermoplastic resin film used. Although not particularly limited, the heat treatment is generally carried out in the molding process of the container. If the heating temperature during the heat treatment is too low, sufficient foamability cannot be obtained, and if the heating temperature is too high, the foaming cells are combined and swelling is likely to occur.

Although not particularly limited, when the foamed layer forming layer is composed of a low-density polyethylene film, the heating temperature may be preferably 100 to 125 ° C, more preferably 110 to 120 ° C. The heating time can be appropriately adjusted according to the heating temperature, but is preferably 3 to 10 minutes, more preferably 5 to 7 minutes. In one embodiment, when the foam layer forming layer is composed of a low density polyethylene film and the printing layer is formed on the foam composition using the ink composition (ii) described above, the heating temperature is 110 to 123 ° C. It is preferable to adjust the heating time to 5 to 7 minutes. It is more preferable to adjust the heating temperature to 115 to 121 ° C. and the heating time to 5 to 7 minutes. When heating is performed under the above conditions, it becomes easy to appropriately control the foaming of the foam cambium during heat processing by the print layer.

Any means such as hot air, electric heat, and electron beam can be used as the heating means. A large amount of heat treatment can be carried out inexpensively by heating with hot air, electric heat, or the like in a tunnel provided with a transport means by a conveyor.

<4> Foam Paper Container One embodiment relates to a foam paper container provided with the foam paper laminate of the above embodiment. The foamed paper container is composed of a container body member and a bottom plate member, and the container body member is formed from the foamed paper laminate of the above embodiment. FIG. 1 is a perspective view showing the structure of a foamed paper container 10A obtained by performing a heat treatment after assembling and molding the container. As shown in FIG. 1, the foamed paper container 10A is composed of a container body member 10 made of a foamed paper laminate and a bottom plate member 12. In the container body member (foamed paper laminate) 10, the high Mp resin film forms the inner wall surface 10a of the container, and the printing layer on the low Mp resin film (foamed layer) forms the outer wall surface 10b of the container.

FIG. 2 is a schematic cross-sectional view showing an enlarged reference numeral I portion of the container body member of the foam paper container shown in FIG. The container body member (foamed paper laminate) 10 includes a high Mp resin film 20, a paper base material 30, and a low Mp resin film (foamed layer) 40 after foaming, in order from the inner wall surface 10a side (see FIG. 1) of the container. And a print layer 50, and the print layer 50 has a base layer 50a and a print pattern 50b.

Molding of foamed paper containers can be carried out by applying well-known technology. For example, a foamed paper laminate (foamed paper laminate before heating) on which a print layer is first formed is punched into a predetermined shape along a mold to obtain a container body member. Similarly, the bottom plate material is punched into a predetermined shape to obtain a bottom plate member. Next, the container body member and the bottom plate member are assembled and molded into the shape of the container by using a conventional container manufacturing apparatus. In the assembly and molding of the container by the container manufacturing apparatus, the high Mp resin film of the container body member forms the inner wall surface, the low Mp resin film forms the outer wall surface, and the laminated surface of the bottom plate member is on the inside. To carry out. By assembling and molding the container with the container manufacturing apparatus in this way and then performing heat treatment, the low Mp resin film can be foamed to form a foamed layer (heat insulating layer), and a foamed paper container having heat insulating properties can be obtained. can.

In one embodiment, when the inner wall surface of the body and the outer wall surface of the body of the foamed paper container are each made of polyethylene film, one surface of the paper base material (inner wall surface of the container) is made of medium-density or high-density polyethylene film. It is preferable to laminate the other surface (outer wall surface of the container) with a low-density polyethylene film. The thickness of each film laminated on the paper substrate is not particularly limited. However, the thickness of the low Mp resin film constituting the outer wall surface of the container body is appropriately set so that the foamed film has a sufficient thickness to function as a heat insulating layer when the film is foamed. Is preferable.

For example, when the outer wall surface of the container body is made of a low-density polyethylene film, the thickness of the film laminated on the paper substrate may be 40 to 150 μm. On the other hand, when the inner wall surface of the container body is made of a medium-density or high-density polyethylene film, the thickness of the film laminated on the paper substrate is not particularly limited. However, it is preferable to appropriately set the thickness of the film so that the permeability resistance of the contents is ensured when used as a heat-insulating foamed paper container. Since the thickness of the film to be laminated on the paper substrate varies depending on the resin material of the film used, it is desirable to be appropriately set by those skilled in the art in consideration of the characteristics of the resin material.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. The "parts" and "%" described below represent "parts by mass" and "% by mass" unless otherwise specified.

<1> Binder resin (1) Raw material for urethane resin (castor oil polyol and other raw materials)
The castor oil polyols used in the synthesis of the following urethane resins are various commercially available polyols and polyols obtained by synthesizing according to a known method shown in JP-A-2005-320437. The raw materials not described as "biomass-derived" in the raw materials described below are raw materials not derived from biomass.

(Castor oil polyol 1)
"URIC HF-2009" manufactured by Itoh Oil Chemicals (a biomass-derived polyol containing a ricinoleic acid-derived structure having a weight average molecular weight of 2,600 as a main component and having 2 functional groups) was used as it was.

(Castor oil polyol 2)
"URIC H-57" manufactured by Itoh Oil Chemicals (a biomass-derived polyol containing a ricinoleic acid-derived structure having a weight average molecular weight of 1,700 as a main component and having 3 functional groups) was used as it was.

(Castor oil polyol 3)
After putting 100 parts of refined castor oil and 0.57 g of potassium hydroxide (KOH) in a pressure vessel, the temperature was raised to 110 ° C. by dehydration under reduced pressure. 200 parts of propylene oxide was added thereto while maintaining the reaction pressure of 4 kg / cm ^2, and the reaction was carried out until the pressure effect was no longer observed. 0.91 g of phosphoric acid was added to this reaction product to neutralize the catalyst, and dehydration and filtration were carried out to obtain a polyol having a hydroxyl value of 58 mgKOH / g (biomass-derived castor oil polyol 3). The weight average molecular weight measured by GPC was 3,400.

(Castor oil polyol 4)
"URIC H-73X" manufactured by Itoh Oil Chemicals (a biomass-derived polyol having a weight average molecular weight of 600 and having a ricinoleic acid-derived structure as a main component, having 3 functional groups) was used as it was.

(Castor oil polyol 5)
After putting 100 parts of refined castor oil and 0.85 g of KOH in a pressure vessel, the temperature was raised to 110 ° C. by vacuum dehydration. 284 parts of propylene oxide was added thereto while maintaining the reaction pressure of 4 kg / cm ^2, and the reaction was carried out until the pressure effect was no longer observed. 1.36 g of phosphoric acid was added to this reaction product to neutralize the catalyst, and dehydration and filtration were carried out to obtain a polyol having a hydroxyl value of 45 mgKOH / g (biomass-derived castor oil polyol 5). The weight average molecular weight measured by GPC was 5,000.

(MPD / AA)
A polyester polyol having a weight average molecular weight of 2,000 composed of 3-methyl 1,5-pentanediol and adipic acid manufactured by Kuraray Co., Ltd. was used.

(MPD / SA)
A polyester polyol having a weight average molecular weight of 2,000 composed of 3-methyl 1,5-pentanediol and sebacic acid (derived from biomass) manufactured by Kuraray Co., Ltd. was used.

(2) Synthesis example of binder resin (urethane resin) (Synthesis example 1)
[Urethane resin PU1]
30 parts of castor oil polyol 1, 70 parts of polyester polyol (hereinafter "MPD / SA") having a weight average molecular weight of 2,000 consisting of 3-methyl 1,5-pentanediol and sebacic acid (derived from biomass), 1,3- 2.0 parts of propanediol (derived from biomass) and 27.4 parts of isophorone diisocyanate (hereinafter referred to as "IPDI") were reacted at 80 ° C. for 5 hours under a nitrogen stream to obtain a resin solution of a urethane prepolymer containing a terminal isocyanate group. ..
Next, 6.2 parts of isophoronediamine (hereinafter "IPDA"), 2.0 parts of iminobispropylamine (hereinafter "IBPA"), 1.0 part of N- (2-hydroxyethyl) ethylenediamine (hereinafter "AEA"), acetic acid. A resin solution of the terminal isocyanate urethane prepolymer prepared above was gradually added to a mixture of 323.4 parts of a mixed solvent of ethyl / 2-propanol (hereinafter “IPA”) = 60/40 (mass ratio) at 40 ° C. The mixture was added and then reacted at 80 ° C. for 1 hour to obtain a urethane resin solution PU1 (solid content 30%) having a weight average molecular weight of 65,000.

The weight average molecular weight of the urethane resin was measured as follows. (Weight average molecular weight)
As a pretreatment, all the amino groups at both ends of the urethane resin are reacted with α, α-dimethyl-3-isopropenylbenzyl isocyanate. Then, for the pretreated urethane resin, Polystyrene GPC LF-604 (manufactured by Shodex) was used as a column, and gel permeation chromatography equipped with an RI detector (manufactured by GPC Shodex, GPC-104) was used as a developing solvent in tetrahydrofuran (GPC-104). The polystyrene-equivalent molecular weight when using THF) was obtained.

(Synthesis Examples 2 to 12)
[Urethane resin PU2 to PU12]
Urethane resins PU2 to PU12 were obtained by the same method as in Synthesis Example 1 except that the materials shown in Table 1 were used. Details of the synthesis are shown in Table 1.

(Synthesis Example 13)
[Urethane resin PU13]
100 parts of MPD / SA (derived from biomass), 2.0 parts of 1,3-propanediol (derived from biomass), and 25.5 parts of IPDI were reacted at 80 ° C. for 5 hours under a nitrogen stream to make a resin of a terminal isocyanate urethane prepolymer. A solution was obtained. A resin solution of the obtained terminal isocyanate urethane prepolymer was gradually added to a mixture of 6.6 parts of IPDA and 317.6 parts of a mixed solvent of ethyl acetate / IPA = 60/40 (mass ratio) at 40 ° C. Next, the reaction was carried out at 80 ° C. for 1 hour to obtain a urethane resin solution PU13 (solid content 30%). The weight average molecular weight of the urethane resin was 68,000.

(Synthesis Example 14)
[Urethane resin PU14]
A urethane resin solution PU14 (solid content 30%) was obtained in the same manner as in Synthesis Example 13, except that 100 parts of a polyether polyol was used instead of MPD / SA (derived from biomass) as the polyol component. The weight average molecular weight of the urethane resin was 62,000.

 

(3) Elongation rate of binder resin Each urethane resin, vinyl chloride / vinyl acetate copolymer (vinyl acetate resin), and nitrocellulose obtained in the above synthetic example are mixed at the ratios shown in Table 2 and then applied and applied. The mixture was dried to prepare coating test samples 1 to 22 (thickness 0.30 mm, width 5.0 mm, length 20.0 mm). For each sample, the elongation rate was measured using a small tensile tester manufactured by Intesco. The measurement was carried out under the conditions of a tensile speed of 100 mm / min and a room temperature of 25 ° C. The results are shown in Table 2.

 

<2> Production example of ink composition (ink example 1)
[Making gravure ink W1]
30 parts of urethane resin solution PU1 (solid content 30%), vinyl chloride-vinyl acetate copolymer resin (solvine TAO: Nissin Chemical Industry Co., Ltd. vinyl chloride / vinyl acetate / vinyl alcohol = 91/2/7 (mass ratio)) (Copolymer resin, solid content 30% ethyl acetate solution)), 30 parts of titanium oxide (Titanics JR-805 manufactured by Teika Co., Ltd.), 20.0 parts of n-propyl acetate, and 15 parts of IPA, which are white pigments, are mixed. , Dispersed in an Eiger mill for 30 minutes to obtain gravure ink W1.

(Ink Examples 2 to 21, Comparative Ink Example 1)
[Making gravure inks W2-W20 and Blue1 and T1]
Gravure inks W2 to W20, Blue1 and T1 were obtained by the same method as in Example 1 except that the raw materials and formulations shown in Table 3 were changed. The abbreviations in the table indicate the following. In the table, the numerical values without the unit notation indicate the part, and the blanks indicate that they are not mixed.
Solvine TA3: Vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group (vinyl chloride / vinyl acetate / hydroxyalkyl acrylate = 83/4/13 (mass ratio) manufactured by Nissin Chemical Industry Co., Ltd.) Solid content 30% Ethyl acetate solution Nitrocellulose (Hereinafter "NC"): Nitrocellulose 1 / 8H (manufactured by Asahi Kasei Co., Ltd.) 30% solid content nitrocellulose solution (derived from biomass) mixed and dissolved in 30 parts of ethyl acetate / 40 parts of IPA.
C. I. Pigment Blue 15: 3: Lionol Blue FG7330 (manufactured by Toyo Color Co., Ltd.)

When the gravure ink W1 and the gravure ink W20 were allowed to stand for one week under the condition of 40 ° C., it was confirmed that the gravure ink W1 was better in terms of ink stability (layer separation) and the like. The gravure ink W1 is an ink using PU1 (a urethane resin having a structural unit derived from castor oil polyol and a structural unit derived from polyester polyol in one polymer chain). On the other hand, the gravure ink 20 is an ink in which PU8 (urethane resin having a structural unit derived from castor oil polyol) and PU14 (urethane resin having a structural unit derived from polyester polyol) are used in combination. Therefore, from the viewpoint of ink stability, it can be seen that the urethane resin in which the structural unit derived from castor oil polyol and the structural unit derived from polyester polyol coexist in the polymer chain is preferable.

 

<4> Production example of foamed paper laminate (1) Production example of foamed paper material The foamed paper material is (step 1) a water vapor blocking layer obtained by extruding and laminating a medium density polyethylene resin (M) on one side of a paper base material. Then, the low-density polyethylene resin (L) was extruded and laminated on the other surface (non-laminated surface) of the paper substrate (step 2).

Various conditions in step 1 and step 2 are as follows.
(Step 1)
Paper substrate: Moisture content 23 kg / m ³ , Basis weight 300 kg / m ³
Medium density polyethylene resin (M): Tosoh's "Petrosen LW04-1", MFR 4.3 g / 10 minutes, density 940 kg / m ³
Extrusion temperature (T die outlet temperature): 320 ° C
Pick-up speed (lamination speed): 50 m / min Air gap: 130 mm
Thickness: 40 μm (thickness of the central part of the polyethylene resin layer)

(Step 2)
Low density polyethylene resin (L); Extrusion temperature (T die outlet temperature) described later: 310 ° C.
Pick-up speed (lamination speed): 60 m / min Air gap: 130 mm
Thickness: 50 μm

The low-density polyethylene resin (L) used in the above step 2 is a foam layer forming layer (B ₀ ). As the low-density polyethylene resin (L), low-density polyethylene resins (L2) and (L3) are used in Examples 23 and 24 and Comparative Example 2, and low-density polyethylene resin (L1) is used in other cases for foaming. Manufactured paper material. Details of the low-density polyethylene resins (L1), (L2) and (L3) are as follows.
Low-density polyethylene resin (L1): Toso Co., Ltd. "Petrosen 07C03C", density 918 kg / m ³ , MFR 15 g / 10 minutes Low-density polyethylene resin (L2): Nippon Polyethylene Co., Ltd. "Novatec LDLC720", density 922 kg / m ³ , MFR 9 g / 10 min Low density polyethylene resin (L3): "SBC818" manufactured by Brasschem, density 918 kg / m ³ , melting point 106 ° C, MFR 8.1 g / 10 min

(2) Production example of forming a print layer on a foam paper material (foam paper laminate before foaming) Using the gravure ink prepared above, a print layer is formed on the foam paper material as described below. did.

(Example 1)
The gravure ink W1 obtained above has a viscosity of 16 seconds with a mixed solvent consisting of methyl ethyl ketone (hereinafter “MEK”): n-propyl acetate (hereinafter “NPAC”): IPA = 40: 40: 20 (mass ratio). Dilute to (25 ° C., Zahn cup No. 3), and use a gravure printing machine with a corrosion of 30 μm on a low-density polyethylene resin (L1) as a foam paper material at a printing speed of 100 m / min to achieve a film thickness of 1. A 5 μm print layer was formed. The thickness of the printed layer was determined from a scanning electron microscope (SEM) photograph (magnification of 5000) of the cross section of the foamed paper laminate. The print layer was measured at any five points, and the average value thereof was taken as the film thickness of the print layer.

(Examples 2 to 25, Comparative Examples 1 to 3)
As shown in Table 4, printing was performed in the same manner as in Example 1 except that each printing ink was used, and a printing layer having a film thickness of 1.5 μm was formed. However, in Example 22, the film thickness of the print layer was 2.5 μm because the overprinting was performed. In Example 23, the low-density polyethylene resin (L2) was used instead of the low-density polyethylene resin (L1), and in Example 24, the low-density polyethylene resin (L1) was replaced with the low-density polyethylene resin (L1). L3) was used.

(3) Example of Production of Foam Paper Laminate A foam paper material (foam paper laminate before foaming) having a print layer manufactured as described above is heat-treated under the following conditions to obtain a low-density polyethylene resin layer (a low-density polyethylene resin layer). L) was foamed to form a foamed layer, and a foamed paper laminate (post-foam laminate) was produced.
Standard condition (A): Heating in an oven at 120 ° C. for 6 minutes (Examples 1 to 24, Comparative Examples 1 to 3)
Condition (B): Heating in an oven at 122 ° C. for 6 minutes (Example 25)

<5> Evaluation of Foam Paper Laminates Various characteristics of the foam paper laminates of Examples 1 to 25 and Comparative Examples 1 to 3 produced as described above were evaluated according to the methods described below. The results of each are shown in Table 4.

<Foamability>
On each surface of the foamed paper laminates of Examples 1 to 25 and Comparative Examples 1 to 3, the step between the ink printed portion and the non-printed portion after the heat treatment (after foaming of the low Mp film) was touched to touch the ink printing portion. The degree of dent was evaluated according to the following criteria. The higher the evaluation value, the better the foam followability and the flatter the printed surface.
(Evaluation criteria)
5: Almost no step with the non-printed part is felt.
4: I feel a slight step with the non-printed part.
3: I feel a considerable difference in level with the non-printed part.
2: I feel that the step with the non-printed part is quite large.
1: I feel the step with the non-printed part is very large.

<Appearance of foam: Fire swelling>
With respect to the foamed paper laminates of Examples 1 to 25 and Comparative Examples 1 to 3, the printed surface of the foamed paper laminate was visually observed. The evaluation criteria are as follows. The results shown in Table 4 are the most frequent values in the results of randomly preparing 10 samples of the foamed paper laminate and observing and evaluating each sample. When there are multiple modes, the value with the lower evaluation is adopted.
(Evaluation criteria)
5: No swelling (no swelling can be confirmed).
4: There is one swelling with a major axis of less than 5 mm ^{per 100 cm 2.
3: There are two} swellings with a major axis of less than 5 mm per 100 cm 2.
2: There are 3 to 5 swellings with a major axis of less than 5 mm ^{per 100 cm 2.} Alternatively, there is one swelling with a major axis of 5 to 20 mm ^{per 100 cm 2.}
1: There are 6 swellings with a major axis of less than 5 mm ^{per 100 cm 2.} Alternatively, there are two or more swellings with a major axis of 5 to 20 mm ^{per 100 cm 2.} Alternatively, there is one or more swellings with a major axis of more than 20 mm ^{per 100 cm 2.}
If multiple swells with different major axes are mixed, a lower evaluation is adopted. Specifically, if there are ^two swellings with a major axis of less than 5 mm and one swelling with a major axis of 5 to 20 mm per 100 cm 2, the evaluation is "2".

<Foam appearance: cracks>
With respect to the foamed paper laminates of Examples 1 to 25 and Comparative Examples 1 to 3, the printed surface of the foamed paper laminate was visually observed in the same manner as in the evaluation of fire swelling. The evaluation criteria are as follows. The results shown in Table 4 are the most frequent values in the results of randomly preparing 10 samples of the foamed paper laminate and observing and evaluating each sample. When there are multiple modes, the value with the lower evaluation is adopted.
(Evaluation criteria)
5: No cracks (no cracks can be confirmed).
4: There is one crack with a length of less than 2 mm ^{per 100 cm 2.}
3: There are 2 to 4 cracks with a length of less than 2 mm ^{per 100 cm 2.}
2: There are 5 to 10 cracks with a length of less than 2 mm ^{per 100 cm 2.} Alternatively, there is one crack with a length of 2 to 5 mm ^{per 100 cm 2.}
1: There are 11 or more cracks with a length of less than 2 mm ^{per 100 cm 2.} Alternatively, there are two or more cracks having a length of 2 to 5 mm ^{per 100 cm 2.} Alternatively, there is one or more cracks having a length of more than 5 mm ^{per 100 cm 2.}
If a plurality of cracks having different lengths are mixed, a lower evaluation is adopted. Specifically, if there is one crack having a length of 1 mm and one crack having a length of 4 mm per ^{100 cm 2, the evaluation is “2”.}

<Heat resistance>
Since it is difficult to directly evaluate the heat resistance of the printed layer during the heat treatment for forming the foam layer, as an alternative test, the foam paper laminate (after foaming) is reheated to improve the heat resistance. evaluated. Specifically, first, with respect to the foam paper laminates of Examples 1 to 25 and Comparative Examples 1 to 3, an aluminum foil cut to the same size as the print layer was superposed on the surface of the print layer (coating film). Next, using a heat seal tester heated to 140 ° C., the aluminum foil portion was pressed at a pressure of ^{2 kg / cm 2 for 1 second.} Next, the aluminum foil was peeled off, the ink area adhering to the aluminum foil was obtained, the ratio of the ink area based on the print layer was calculated, and the heat resistance was evaluated. The evaluation criteria are as follows.
(Evaluation criteria)
5: No ink adhesion to the aluminum foil (ink adhesion cannot be confirmed).
4: Ink adhesion to the aluminum foil is confirmed, but it is less than 3%.
3: Ink adhesion to the aluminum foil is 3% or more and less than 10%.
2: Ink adhesion to aluminum foil is 10% or more and less than 30%.
1: Ink adhesion to aluminum foil is 30% or more.

<Ethanol resistance>
For the foamed paper laminates of Examples 1 to 25 and Comparative Examples 1 to 3, 70% ethanol (ethanol: water = 70) was added to the friction element against the surface of the printed layer (coating film) on the low melting point film foamed by the heat treatment. : 30) was loaded and reciprocated once while loading the kanakin (JIS L 0803). When going back and forth between Kanakin, a load of 200 g was applied by a Gakushin tester (manufactured by Tester Sangyo Co., Ltd.). Then, the coating film was visually observed, the ratio of the area where the coating film (ink) was peeled off was calculated based on the total area of the coating film before the test, and the ethanol resistance was evaluated. The evaluation criteria are as follows.
(Evaluation criteria)
5: Ink peeling is less than 30%.
4: Ink peeling is 30% or more and less than 40%.
3: Ink peeling is 40% or more and less than 60%.
2: Ink peeling is 60% or more and less than 70%.
1: Ink peeling is 70% or more.

Although not shown in Table 4, as other characteristics, the thickness of the foam layer and the number of foam cells of the foam paper laminate were measured according to the method described below. As a result, for the foamed paper laminates other than Comparative Example 3, the thickness of the foamed layer is 500 μm or more, and the number of foamed cells is 1250 cells / 1 cm ² or more, so that sufficient heat insulating properties are obtained in practical use. I was able to confirm that it was possible. On the other hand, the foam sheet laminate of Comparative Example 3, although the thickness of the foamed layer was greater than 500 [mu] m, a number of foamed cells is less than 1000/1 cm ^2, not possible to obtain sufficient heat insulating property in a practical rice field.

(Number of foam cells)
The printed layer of the foamed paper laminate was removed with methyl ethyl ketone (MEK) to expose the surface of the foamed thermoplastic resin layer (foamed layer). Next, the surface of the foam layer was observed using an optical microscope (AZ100M manufactured by Nikon Corporation) (magnification 25 times), and an independent cell existing within a range partitioned by a certain length in the vertical and horizontal (XY) directions. The number of independent cells was obtained, and the value calculated as the number of independent cells per ^{1 cm 2 was obtained.} Observation was performed at any 5 points, and the average value of these was taken as the number of foamed cells.

(Film thickness of foam layer)
The film thickness of the foam layer was determined by observing the cross section of the foam paper laminate with an optical micrograph and measuring the height from the upper surface of the paper substrate to the lower surface of the print layer. Further, the film thickness before foaming corresponds to the film thickness of the foamed layer forming layer. Therefore, the value obtained by measuring the film thickness of the low-density polyethylene resin formed as the foam layer forming layer was used.

 

From the results shown in Table 4, according to the embodiment (Example) of the present invention, by using a urethane resin containing a structural unit derived from castor oil polyol as a binder resin, excellent heat resistance, foaming followability, and foaming are obtained. It can be seen that the appearance and ethanol resistance can be obtained. In particular, it can be seen that the heat resistance can be easily improved when the castor oil polyol and the polyester polyol are used in combination as the polyol component. On the other hand, in the comparative example using the urethane resin containing no structural unit derived from castor oil polyol, the desired properties could not be obtained, and in particular, the heat resistance and alcohol resistance were significantly reduced. ..
From the above, according to the present invention, the present invention has a printed layer containing a biomass resin, excellent heat resistance, foaming followability, foaming appearance, and ethanol resistance are obtained, and is suitable as a member of a foamed paper container. It can be seen that a usable foamed paper laminate can be provided.

(Explanation of code)
10 Foamed paper laminate (container body member)
10A Foamed paper container 10a Outer wall surface of container 10b Inner wall surface of container 12 Bottom plate member 12
20 High Mp resin film (thermoplastic resin layer (A))
30 Paper base material 40 Low Mp resin film after foaming (foamed thermoplastic resin layer (B), foamed layer (B))
50 print layer 50a base layer 50b print pattern

Claims (6)

1. A foam paper composed of a base paper, a thermoplastic resin layer (A) provided on one side of the base paper, and a foamed thermoplastic resin layer (B) provided on the other side of the base paper, and the foaming heat. A foamed paper laminate provided with a printing layer provided on the thermoplastic resin layer (B).
   The printed layer contains at least a binder resin and contains
   The binder resin is a foamed paper laminate containing a urethane resin having a structural unit derived from castor oil polyol.
2. The urethane resin further has a structural unit derived from a polyester polyol which is a condensate of a dibasic acid and a diol, and has a structural unit derived from the castor oil polyol (a1) and a structural unit derived from the polyester polyol (a2). The foamed paper laminate according to claim 1, wherein the mass ratio (a1) / (a2) is 75/25 to 10/90.
3. The foamed paper laminate according to claim 1 or 2, wherein the content of the structural unit derived from the polyether polyol is 8% by mass or less based on the total mass of the urethane resin.
4. The foamed paper laminate according to any one of claims 1 to 3, wherein the castor oil polyol has a weight average molecular weight of 1,000 to 5,000.
5. The binder resin further contains a vinyl chloride / vinyl acetate copolymer, and the content of the vinyl chloride / vinyl acetate copolymer is 5% by mass or more and 50% by mass or less based on the total mass of the binder resin. , The foamed paper laminate according to any one of claims 1 to 4. The
6. The foamed paper laminate according to any one of claims 1 to 5, wherein the elongation rate of the binder resin is 400% to 3,000%.

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