JP5708001B2 - Cover varnish - Google Patents

Description

  In the present invention, when a thermoplastic resin such as a low-density polyethylene resin, a medium-density polyethylene resin, a polypropylene resin, or an ethylene-propylene copolymer is melt-extruded and laminated to a printed material coated with ink, the thermoplastic resin and the printed material The present invention also relates to a varnish set for instant food container lids with a hot water separator having excellent peelability.

  As a conventional instant food container lid with a hot-water cup, a surface sheet having a release surface formed by application of a release varnish mainly composed of thermoplastics such as nitrocellulose resin or polyurethane resin or polyamide resin, or a mixture thereof; and There is known a structure in which a hot-cut hole is exposed by laminating and pressing a composite sheet and peeling off a surface sheet at the time of use.

  However, the peelability is still insufficient with respect to the required performance of the lid-type lid material for the peelable instant food container.

  Therefore, as a result of repeated research to satisfy the peeling performance, as disclosed in JP-A-2000-203653, a varnish containing 5% by weight to 95% by weight of wax as a release agent in the coating film is obtained. However, since wax has a low melting point, there is a problem that the dependence on heat is large and the coating film causes cohesive failure.

  In order to satisfy the peeling performance, as disclosed in JP-A-2000-219278, a mixed varnish of a nitrocellulose resin, a urethane resin, an aminoalkyd resin, a polyamide resin, and a polyester resin is used as a sealing layer. A technique is known that prevents permeation (easily peelable deterioration) of the release layer and brings out release performance by applying.

  Furthermore, in order to satisfy the peeling performance in long-term warming / humidified storage, as disclosed in JP-A-2006-346993, a polyamide in the varnish that forms an easy peeling region that forms a release layer and a sealing layer. A technique is known in which the mixing weight ratio of the resin and the nitrocellulose resin is in the range of 30:70 to 90:10.

JP 2000-203653 A JP 2000-219278 A JP 2006-346993 A

  However, the above easy release layer formed from the conventional release layer and the sealing layer causes cohesive failure between the varnish layers in either the release layer or the sealing layer, and has an appropriate peeling property as a hot water lid material. It was not obtained, causing appearance deterioration after peeling.

  The problem to be solved by the present invention is the suitability in the case where a varnish is used when forming an easily peelable region formed from a sealing layer and a release layer in a hot water lid of an instant food container. The present invention provides an easily peelable varnish for a hot water lid of an instant food container that does not deteriorate even when stored for a long time under high temperature and high humidity.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a varnish set using a specific resin gives an appropriate peel strength and a good peel appearance, thereby completing the present invention. It came to do.

That is, the present invention
A top sheet (A) obtained by partitioning an easy-peeling region formed from the sealing layer and the release layer and an adhesive region;
A varnish set for an instant food container lid with hot water cut used for an instant food container lid with hot water cut composed of a composite sheet (B) laminated and adhered to the easily peelable region of the top sheet (A). And
Varnish (1) for forming a sealing layer for forming the easy peeling region
And a varnish (2) for forming a release layer for forming the easy release region
On the varnish set consisting of.
However, it is the following (a) to (e).
(A) The composite sheet (B) has a low density polyethylene layer (adhesive resin layer) obtained by extrusion laminating on the surface in contact with the easily peelable region of the top sheet (A).
(A) Varnish (1) and varnish (2) contain a polyamide resin and a nitrocellulose resin, respectively.
(C) The average degree of polymerization of the nitrocellulose resin is 50 to 150.
(D) The polyamide resin has a weight average molecular weight of 7000-30000.
(E) The content (a1) (weight%) of the polyamide resin in the varnish (1) defined by the general formula (1) is 30 <a1 <76.
And
The content (a2) (% by weight) of the polyamide resin in the varnish (2) defined by the general formula (1) is 76 ≦ a2 <99.
It is.
General formula (1)

Further, in the present invention, the content (a1) and (a2) of the polyamide resin in the varnish (1) and the varnish (2)
a2-a1 ≧ 4%
The present invention relates to a varnish set for an instant food container lid with a hot water cutout.

  The present invention also relates to an instant food container lid with hot water and an instant food container lid with hot water using the varnish set for instant food container lid with hot water.

  With the varnish set provided by the present invention, it is possible to obtain a hot-watered instant food container lid material having an appropriate peel strength and a good peel appearance, and its peelability does not deteriorate even under long-term storage at high temperature and high humidity. Excellent practical effect as an instant food container lid with hot water.

FIG. 2 is an explanatory view showing an embodiment of an instant food container with hot water cutaway in a side cross section according to the present invention. It is explanatory drawing which represented one Embodiment of the instant food container with a hot water dispenser of the present invention by the plane. It is an example of the side view which peeled the surface sheet of the instant food container with a hot water dispenser of this invention, and formed the hot water cut end.

  Hereinafter, the varnish set for instant food container lid material with hot water cutting according to the present invention will be described in more detail. The varnish set for instant food container lid material with hot water cutting according to the present invention has a back surface of a top sheet (A) having a pull tab (30) at the peripheral edge made of, for example, fine paper (20) as shown in the side cross section of FIG. The sealing layer (L1) and the release layer (L2) are sequentially applied.

  Moreover, the surface sheet (A) having the easily peelable layer (LA) obtained above is a composite formed by laminating an adhesive resin layer (10), a metal foil layer (12), and a sealant layer (11) in this order. It is laminated and adhered to the adhesive resin layer (10) of the sheet (B) to form an instant food container lid with a hot water dispenser.

  As shown in the plan view of FIG. 2, the above-mentioned instant food container lid material with a hot water cut is formed with a hot water cut shape in one or a plurality of places on the composite sheet (B) on the pull tab (30) side. A half-cut (40) is formed, and the adhesive resin layer (10) surface and the sealing layer (L1) surface of the composite sheet (B) in the half-cut region for hot water cut-off formation are within the half-cut region. An instant food container lid with hot-water cups with an adhesive portion formed thereon, as shown in FIG. 3, pulling up the pull tab (30) and partially removing the top sheet (B) on the surface of the easy peeling region (L1) The hot water cut opening (50) can be opened by peeling from the lid.

  Further, the sealing layer (L1) forming the above easy-release region (LA) is composed of varnish (1) and the release layer (L2) is composed of varnish (2), both of which contain polyamide resin and nitrocellulose resin as binders. And the weight average molecular weight of this polyamide resin is the range of 7000-30000, and the range of 9000-25000 is preferable. When the weight average molecular weight of the polyamide resin is less than 7000, the easily peeled area to be formed has poor surface tack and does not peel off. On the other hand, when it exceeds 30000, the film of the easily peeled area becomes hard and adhesive. It is not preferable because it is not laminated and adhered to the resin layer, and the content protection suitability deteriorates.

Also,
The content (a1) (weight%) of the polyamide resin in the varnish (1) defined by the general formula (1) is 30 <a1 <76.
And the content (a2) (weight%) of the polyamide resin in the varnish (2) defined by the general formula (1) is 76 ≦ a2 <99.
It is preferable that
General formula (1)

  When the content a1 of the polyamide resin in the varnish (1) is a1 ≦ 30, it is not preferable because the peelability of the easily peelable region is reduced. Moreover, when the content a1 of the polyamide resin of the varnish (1) is 76 <a1, the peelability is too good and the content protection suitability is deteriorated, which is not preferable. When the content a2 of the polyamide resin in the varnish (2) is a2 <76, it is not preferable because the peelability of the easily peelable region is reduced. Further, when the content a2 of the polyamide resin of the varnish (2) is 99 ≦ a2, the peelability is too good and the content protection suitability is deteriorated, which is not preferable.

  Furthermore, it is preferable that the content a1 and a2 of the polyamide resin in the varnish (1) and the varnish (2) are in the range of a2−a1 ≧ 4%. When the content a1 and a2 of the polyamide resin in the varnish (1) and the varnish (2) are a2-a1 <4%, the content of the polyamide resin is approximate, so the varnish (1) and the varnish (1) When the compatibility of the varnish (2) is too good and the product is stored under high temperature and high humidity conditions for a long time, the integration of the sealing layer (L1) and the release layer (L2) is promoted, and the release layer (L2) This does not bring out sufficient performance, and causes poor appearance and poor peeling after peeling.

  The polyamide resin used in the present invention is a thermoplastic polyamide that can be produced by a conventionally known method obtained by polycondensation of a polybasic acid and a polyvalent amine, and the production method is not particularly limited. Absent. Moreover, it is preferable that the softening point of a polyamide resin is the range of 80-150 degreeC. When the softening point is less than 80 ° C., the easily peeled area to be formed suffers from a problem that the surface tack is cut poorly and does not peel. Conversely, when it exceeds 150 ° C., the film in the easily peeled area becomes hard and appearance such as cohesive failure Since it causes a defect, it is not preferable.

  The nitrocellulose resin used in the present invention is obtained as a nitrate ester obtained by reacting natural cellulose with nitric acid to replace the three hydroxyl groups in the 6-membered ring of anhydrous glucopyranose groups in the natural cellulose with nitrate groups. And those having an average degree of polymerization in the range of 50 to 150 are preferably used. When the average degree of polymerization is less than 50, the easily peeled area to be formed suffers from a problem that the surface tack is cut badly and does not peel. Conversely, when it exceeds 150, the solubility in the solvent and the compatibility with the polyamide resin decrease. This is not preferable.

  The varnish set for instant food container lid material with hot water cutting of the present invention can use various organic solvents for viscosity adjustment, and is not particularly limited, but examples thereof include ethanol, n-propanol. Alcohols such as i-propanol, n-butanol, i-butanol, t-butanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-i-propyl ether, (Poly) alkylene glycol monoalkyl ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-i-propyl ether; (Poly) alkylene glycol monoalkyl ether acetates such as dimethyl ether ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate and diethylene glycol monoethyl ether acetate; other ethers such as diethylene glycol dimethyl ether and diethylene glycol diethyl ether; Ketones such as cyclohexanone, 2-heptanone, 3-heptanone; esters such as ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate; 3-methoxybutyl acetate, 3-methyl Esters such as -3-methoxybutyl acetate; aromatic hydrocarbons such as toluene and xylene; N-methylpyrrolidone, N N- dimethylformamide, N, N- amides dimethylacetamide; can be mentioned petroleum-based solvents such as aroma-free.

  Among these solvents, those containing a solvent having a boiling point of preferably 40 to 120 ° C., particularly preferably 60 to 100 ° C., such as aromatic hydrocarbons, ketones, alcohols and esters are desirable. .

In this invention, a solvent can be used individually or in mixture of 2 or more types.
The varnish set for instant food container lid material with hot water cutting according to the present invention includes fine powder silica such as gas phase method silica, wet method silica, organic treatment silica, alumina treatment silica, etc. Additives such as polyethylene wax, fatty acid amide wax, antifoaming agent and leveling agent can also be blended.

  As a base material (surface sheet) that constitutes the lid for a hot water container of the instant food container having the varnish set for the instant food container lid material of the present invention, the surface needs to be excellent in printability. By applying the above varnish set twice with a sealing layer and a release layer, an easily peelable gravure printed material for an instant food container lid with hot water can be obtained.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these Examples. In the present invention, unless otherwise specified, “part” and “%” represent “part by weight” and “% by weight”, respectively.

<Adjustment of polyamide varnish>
30 parts of a polyamide resin having a weight average molecular weight of 6000 (Rheamide S-8200 manufactured by Kao Co., Ltd.) is mixed and dissolved in 50 parts of toluene and 20 parts of isopropyl alcohol to obtain a polyamide varnish for testing having a solid content of 30% (resin A). Got.

<Adjustment of polyamide varnish>
30 parts of a polyamide resin having a weight average molecular weight of 9000 (Rheamide S-2110PL manufactured by Kao Co., Ltd.) is mixed and dissolved in 50 parts of toluene and 20 parts of isopropyl alcohol to obtain a polyamide varnish for test having a solid content of 30% (resin B). Got.

<Adjustment of polyamide varnish>
30 parts of a polyamide resin having a weight average molecular weight of 25000 (Rheamide S-2800 manufactured by Kao Co., Ltd.) is mixed and dissolved in 50 parts of toluene and 20 parts of isopropyl alcohol to obtain a polyamide varnish for test having a solid content of 30% (resin C). Got.

<Adjustment of polyamide varnish>
30 parts of a polyamide resin having a weight average molecular weight of 31000 (Rheamide SP-40N manufactured by Kao Co., Ltd.) is mixed and dissolved in 50 parts of toluene and 20 parts of isopropyl alcohol, and a test polyamide varnish having a solid content of 30% (resin D) Got.

<Preparation of acrylic varnish>
30 parts of acrylic resin (JONCRYL611, manufactured by BASF Corp.) having a weight average molecular weight of 8100 was mixed and dissolved in 70 parts of ethyl acetate to obtain a test acrylic varnish (resin E) having a solid content of 30%.

<Adjustment of polyurethane varnish>
In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas introduction tube, 240.6 parts of polyester diol having a number average molecular weight of 2000 obtained from adipic acid and 3-methyl-1,5-pentanediol 39.8 parts of isophorone diisocyanate and 60.0 parts of ethyl acetate were charged and reacted at 90 ° C. for 6 hours under a nitrogen stream. Next, 20.12 parts of isophoronediamine, 0.75 part of acetamide, 430.0 parts of ethyl acetate, and 210.4 parts of isopropyl alcohol were added to obtain a polyurethane resin varnish (resin F) having a solid content of 30% and a weight average molecular weight of 10,000. It was.

<Adjustment of nitrocellulose varnish>
30 parts of nitrocellulose (1 / 8H, manufactured by Asahi Kasei Co., Ltd.) having an average degree of polymerization of 50 are mixed and dissolved in 30 parts of ethyl acetate and 40 parts of isopropyl alcohol to give a test nitrocellulose varnish having a solid content of 30% ( Resin G) was obtained.

[Varnish A to V]
The said adjustment varnish and polyethylene-type wax were mixed by the mixing | blending shown in Table 1, and the varnish A to V for lid | cover materials was obtained.

[Examples 1-17, Comparative Examples 1-4]
Next, using the varnish for instant food container lid material with hot water cut obtained above, using a gravure proofing machine on the back side of a single-sided art paper with a basis weight of 127.9 / m ^2, a 30 micron solid version for gravure In the order shown in Table 2, the sealing layer and the release layer were printed in this order to obtain an easily peelable gravure print for the lid.

Furthermore, the melted low density polyethylene resin was extruded on the easily peelable gravure printing surface for hot water lid material obtained above to obtain a laminate.
Immediately after laminating the above laminate and after 10 days and 60 days in an atmosphere at a temperature of 50 ° C. and a humidity of 80%, the peel strength of the polyethylene and the degree of varnish transfer to the peeled polyethylene (degree of cohesive failure) were evaluated. The results are shown in Table 2, and easy peelability was evaluated.
(Peel strength) The laminate was cut into a width of 15 mm, and the strength when the polyethylene was peeled at an angle of 90 ° with respect to the pull direction at a pull speed of 300 mm / min was defined as the peel strength.
(Peel appearance) The amount of ink transferred to the polyethylene side of the sample used in the peel strength measurement was visually determined.
-Evaluation criteria-
○: Ink is not removed and appearance is good
Δ: Ink is slightly removed, but there is no practical problem.
X: Many inks are taken.

From the results in Table 2,
Acrylic resin / nitrocellulose resin mixed varnish (Comparative Example 3)
And polyurethane resin / nitrocellulose resin mixed varnish (Comparative Example 4)
The peelability of the release varnish and the sealing varnish used was poor.

  Further, in the polyamide resin / nitrocellulose resin mixed varnish, the varnish set (Comparative Example 1) having a weight average molecular weight of 6000 of the polyamide resin was not satisfactory because the peeling performance deteriorated with time.

  Furthermore, the varnish set (comparative example 2) whose weight average molecular weight of a polyamide resin is 31000 caused the adhesive defect, and the defect of the content protection aptitude was confirmed.

On the other hand, Examples 1 to 9 and Reference Examples 10 to 17 in which varnishes B, C, H, I, and M to V were applied in the peeling region formed from the peeling layer and the sealing layer are peel appearances. Moreover, the deterioration with time was good and the film was sufficiently peelable.

  Therefore, according to the present invention, it is possible to obtain an instant food container lid with a hot water cut which has an appropriate peel strength in production and a good peel appearance, and the peelability does not deteriorate even under high temperature and high humidity storage for a long time. Demonstrates excellent practical effects as an instant food container lid.

DESCRIPTION OF SYMBOLS 10 ... Adhesive resin layer 11 ... Sealant layer 12 ... Metal foil layer 20 ... Fine paper 30 ... Pull tab 40 ... Half cut 50 for hot water cut formation ... Hot water cut
LA ・ ・ ・ Easy peeling area
L1 ・ ・ ・ Sealing layer
L2 ・ ・ ・ Peeling layer
A ... Surface sheet
B ... Composite sheet

Claims (3)

A top sheet (A) obtained by partitioning an easy-peeling region formed from the sealing layer and the release layer and an adhesive region;
A varnish set for an instant food container lid with hot water cut used for an instant food container lid with hot water cut composed of a composite sheet (B) laminated and adhered to the easily peelable region of the top sheet (A). And
Varnish (1) for forming a sealing layer for forming the easy peeling region
And a varnish (2) for forming a release layer for forming the easy release region
Varnish set consisting of.
However, it is the following (a) to (e).
(A) The composite sheet (B) has a low density polyethylene layer (adhesive resin layer) obtained by extrusion laminating on the surface in contact with the easily peelable region of the top sheet (A).
(A) Varnish (1) and varnish (2) contain a polyamide resin and a nitrocellulose resin, respectively.
(C) The average degree of polymerization of the nitrocellulose resin is 50 to 150.
(D) The polyamide resin has a weight average molecular weight of 7000-30000.
(E) The content (a1) (weight%) of the polyamide resin in the varnish (1) defined by the general formula (1) is 30 <a1 <76.
And
The content (a2) (% by weight) of the polyamide resin in the varnish (2) defined by the general formula (1) is 76 ≦ a2 <99.
It is.
General formula (1)

The polyamide resin contents (a1) and (a2) in the varnish (1) and the varnish (2) are:
a2-a1 ≧ 4%
Claim 1 Symbol placement Yu Setsuzuke instant food containers lid varnishes set, characterized in that it. An instant food container lid with hot water cut using the varnish set for an instant food container lid with hot water cut according to claim 1 or 2 .

Images