JP2764147B2 - Heat resistant ink - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a heat-resistant printing ink for printing on an aluminum foil surface. More specifically, printing for the purpose of printing by a printing method such as gravure printing or flexographic printing on the surface of the aluminum foil for packaging material, especially the aluminum foil for PTP (Press Through Pack) packaging on which the heat-sealing resin layer is provided. The present invention relates to an ink which has excellent heat resistance in a printing ink film and does not easily flow due to heat and pressure.

(Prior art) The general form of PTP packaging consists of two parts: a processed molded article of a plastic sheet in which a pocket is formed as a container part for storing contents, and an aluminum foil as a lid part. Consists of As the plastic forming the container body, a vinyl chloride resin sheet has been used for a long time because of its excellent workability. In recent years, a polypropylene sheet has been used because of its excellent moisture-proof property and its low cost. ing. Some papers such as glassine paper are used as the base material of the lid material, but aluminum foil is mostly used.

Aluminum foil which is the base material of the lid material is printed with letters and designs on one or both sides, and on top of it, colorless or colored as necessary, a transparent heat-resistant overcoat or plastic film Subject to
On the opposite side, a plastic sheet is formed and coated with a heat-sealable resin composition or heat-sealable so that it can be adhered to the flange portion of the container provided with the pocket by heating and pressing. Is usually performed by fusing or adhering a thermoplastic resin film via an adhesive to form a heat-sealing resin layer.

In the packaging operation, the filling of the contents is performed by storing the contents in a pocket provided in a vinyl chloride resin sheet or a polypropylene sheet serving as the container and then heating the aluminum foil serving as the lid member on the opening side thereof. By laminating the sealing resin layer so that it contacts, heat the aluminum foil from the opposite side of the heat sealing resin layer with a heat sealing bar or drum and simultaneously pressurize and fuse it to the non-pocket portion of the plastic container. Will be performed.

The heating and pressing conditions vary depending on the type of the laminated material, but the heat sealing temperature is 100 ° C to 200 ° C, generally between 120 ° C and 180 ° C, and the heat sealing pressure is set to 1 to 3 kg / cm ^2. Often have.

Gravure printing is often used for printing letters and designs on the aluminum foil of the lid, and nitrocellulose, polyamide resin, vinyl chloride / acetic acid, etc. are used as the ink vehicle depending on the final use as a packaging material, post-processing conditions, etc. An organic solvent solution, an aqueous solution, or an aqueous dispersion of various resins such as a vinyl copolymer resin, an acrylic resin, a chlorinated rubber, an epoxy resin, a polyester resin, and a polyurethane resin are properly used.

(Problems to be Solved by the Invention) In recent years, however, the speed of the line in the filling process of contents has been increased in order to reduce the manufacturing cost. There is a tendency to set the temperature and pressure inevitably higher than usual, so that the characters and designs printed on the aluminum foil between the aluminum foil as the base material of the lid material and the heat sealing resin layer are There has been a problem that a color flow phenomenon occurs at the time of heat sealing.

In other words, the rise in heat sealing temperature increases the tendency of the printing ink vehicle to soften and flow, and also increases the pressure. It causes bleeding and uneven density to cause color flow phenomenon.

(Means for Solving the Problem) The present inventors have proposed aluminum foil for packaging materials, especially PTP (P
(Ress Through Pack) This is a printing ink for gravure printing on the surface of the aluminum foil for the lid material on which the heat-sealing resin layer is provided in the packaging, and the temperature and pressure at which the lid material is heat-sealed to the container are increased. As a result of repeated studies to develop a heat-resistant ink for aluminum foil which does not cause the above-mentioned color flow phenomenon, it has been found that a phenoxy resin (A) is 50 to 90% and an amino resin (B) is 10 to 50% as a main component. A film printed on an aluminum foil using an ink containing an organic solvent solution of a resin mixture ((A) + (B) = 100%) as a vehicle is provided with a heat-sealing resin layer thereon. ,
When heat sealing in a plastic container such as vinyl chloride resin or polypropylene resin, even if heat sealing at a high temperature of 200 ° C or higher, for example, a heat sealing temperature of 220 ° C, and a high pressure of 5 kg / cm ² , the color flow phenomenon occurs. The inventors have found that this does not occur and arrived at the present invention.

The phenoxy resin (A), which is the first main component of the resin mixture used in the vehicle of the heat-resistant ink for aluminum foil of the present invention, is generally obtained from the reaction of a polyglycidyl ether compound with an organic or inorganic polybasic acid. It is a thermoplastic resin having a polymer structure. For example, typical examples include epichlorohydrin and bisphenol A
There are many products produced by reacting a bisphenol compound such as bisphenol A with a bisphenol-type epoxy resin, which are commercially available, but are not particularly limited, and those having a specific composition can be arbitrarily used. Any of synthesized ones and those appropriately selected from commercial products can be used.

The amino resin as the second main component is not particularly limited, but a urea resin, a melamine resin, a guanamine resin or a co-condensation resin thereof is suitable.

As the melamine resin, an alkyl etherified melamine resin such as a methyl etherified melamine resin, a butyl etherified melamine resin or an isobutyl etherified melamine resin is preferable.

As the urea resin, an alkyl etherified urea resin such as a butyl etherified urea resin and an isobutyl etherified urea resin is preferable.

As the guanamine resin, an alkyletherified guanamine resin of guanamines having various substituents such as acetoguanamine and benzoguanamine can be used, and a methyletherified benzoguanamine resin and a butyletherified or isobutyletherified enzaguanamine resin are particularly preferable.

The vehicle of the heat-resistant ink for aluminum foil of the present invention contains a phenoxy resin (A) as a main component as a resin component.
The use of a film-forming agent other than the amino resin (B) and the amino resin (B) may be used in combination. In particular, the use of an acrylic resin, an epoxy resin, a cellulose derivative, or the like is suitable in terms of compatibility and physical property modification.

The solvent for the vehicle of the heat-resistant ink for aluminum foil of the present invention is not particularly limited, and aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, esters, ethers, ketones, alcohols, etc. Any of those generally used for blending gravure inks of the organic solvent type can be used, so that the resin mixture of the phenoxy resin (A) and the amino resin (B) is dissolved and the printability is satisfied. Can be arbitrarily compounded.

The coloring agent, which is another main component of the printing ink, is not particularly problematic in use as long as it is a pigment, dye or extender used in a normal gravure ink for aluminum foil, and is optional according to the purpose. And can be blended.

Further, addition of additives usually used in paints and inks, for example, pigment dispersants, leveling agents, lubricants, plasticizers and the like does not cause any problem.

The heat-resistant ink for aluminum foil of the present invention is intended to be mainly printed by a gravure plate,
There are no particular conditions in the printing step, and it is generally appropriate to perform drying at 200 ± 50 ° C. for 2 to 15 seconds.

(Function and Effect) As described above, the ink of the present invention is an ink for printing on aluminum foil mainly by a gravure method, and the printing ink film obtained by printing using the ink has heat resistance. It is characterized by the following.

The vehicle of the above ink is phenoxy resin (A) 50 ~
Resin mixture containing 90% and amino resin (B) 10 to 50% as main components (provided that (A) + (B) = 100%)
Wherein the proportion of the phenoxy resin (A) in the main component exceeds 90% and the amino resin (B)
If the ratio is less than 10%, the heat resistance of the printing ink film is reduced and a color flow phenomenon occurs at the time of heat sealing. When the ratio of the phenoxy resin (A) is lower than 50% and the ratio of the amino resin (B) exceeds 50%, the heat resistance of the printing ink film is good, but the adhesion to aluminum foil is reduced. I can not use it.

 Hereinafter, a further example will be described.

Example 1 Based on the composition shown in Table 1, a phenoxy resin and a butyl etherified melamine resin were mixed and stirred to prepare a vehicle. To the obtained vehicle, a blue pigment Fastgen Blue GNPT was added, mixed and wetted, and diluted by adding 80% of the additive solvent shown in Table 1 to a volume of 50%.
2 at 1700 rpm using a batch type tabletop sand mill of 0CC
The mixture was treated for 0 minutes to be dispersed, and the remaining solvent was added to prepare an ink.

Using a gravure plate having a mesh density of 120 lines and a cell depth of 25μ, the resulting ink was used to print characters and lines on the matte surface of a semi-rigid single-gloss aluminum foil with a thickness of 20μ. Was applied so that the dry film thickness was 6 μm to provide a heat-sealing resin layer.

(Heat sealable coating agent) Byron 300 50 parts (Toyobo Co., Ltd. polyester resin) Vinylite VMCH 50 parts (U.S.A. U.S.A. vinyl chloride copolymer) Toluene 150 parts Methyl ethyl ketone 150 parts Total 400 parts After performing a grid test (JIS K-5400) on an aluminum foil sample provided with a heat-sealing resin layer, a cellophane tape was stuck on the test surface and peeled off. The peeling state of the printing ink film was observed to observe the adhesion. Examined.

Next, another aluminum foil sample was placed on a 250μ thick rigid vinyl chloride resin sheet (VS120 manufactured by Sumitomo Bakelite Co., Ltd.).
2) Laminate so that the heat-sealing resin layer is in contact with the heat-sealing resin layer.
° C., subjected to heat sealing under conditions of a heat sealing pressure of 5.5 kg / cm ² and pressing time 1 sec, were examined color flow resistance by observing the heat sealing surface.

The test results are shown in Table 1 together with the composition of the printing ink, but no peeling of the printing ink film was observed, no flow of the printing ink film on the heat-sealed surface was observed, and sufficient adhesion and heat resistance were exhibited. .

Example 2 In Example 1, when the vehicle was prepared, the ratio of the phenoxy resin was within the range of the present invention and was close to the upper limit, and therefore, the ratio of the amino resin was close to the lower limit. The production test of the printing ink and the performance test of the printing ink film were performed in the same manner as in Example 1.

The composition and the performance evaluation are shown in Table 1 in the same manner as in Example 1, but the adhesion and color flow of the printing ink film were all good.

Example 3 In Example 1, when the vehicle was prepared, the ratio of the phenoxy resin was within the range of the present invention and was close to the lower limit, and therefore, the ratio of the amino resin was close to the upper limit. The production test of the printing ink and the performance test of the printing ink film were performed in the same manner as in Example 1.

The composition and performance evaluation are shown in Table 1 as in Example 1.

The adhesion and color flow of the printing ink film were all good.

[Comparative Example 1] In Example 1, when the vehicle was prepared, the ratio of the phenoxy resin was lower than the lower limit of the range of the present invention, and therefore, the case where the value of the amino resin exceeded the upper limit was used. The other conditions and operations were the same as in Example 1.

The composition and the performance evaluation are shown in Table 1 in the same manner as in Example 1.

Although the color flow property of the printing ink film was good, 80% or more of the printing ink film was peeled off by the cellophane tape in the adhesion test, and it was recognized that the adhesion was significantly reduced.

[Comparative Example 2] In the case of preparing a vehicle in Example 1, a value exceeding the upper limit of the range of the present invention was used as the ratio of the phenoxy resin, and therefore, the case where the ratio of the amino resin was lower than the lower limit was used. The conditions and operations are completely the same as those in the first embodiment.
Was performed in the same manner as described above.

The composition and performance evaluation are shown in Table 1 as in Example 1. Regarding the adhesion of the printing ink film, no damage such as peeling was observed at all, and the printing ink film was good. However, in the color flow test, the printing ink film such as characters and lines in the heat-sealed portion caused flow by heat and pressure. It was recognized that the profile became indistinct, the density was reduced, and unevenness occurred, and there was no heat resistance.

Claims (1)

(57) [Claims] 1. A heat-resistant ink to be printed on an aluminum foil in a heat-sealing lid material based on an aluminum foil, wherein the phenoxy resin (A) is 50 to 90% by weight (the same applies hereinafter). ) And a resin mixture containing amino resin (B) 10 to 50% as a main component (provided that (A) + (B) = 10)
0%) is a heat-resistant ink for aluminum foil using an organic solvent solution as a vehicle.