JP6451281B2 - Heat-sealable resin composition - Google Patents

Description

The present invention relates to a heat-sealable resin composition for coating various plastic film substrates used as packaging materials for the purpose of imparting heat-sealability. More specifically, the present invention relates to a heat-sealable resin composition that is excellent in blocking resistance and exhibits good heat-seal strength even when the heat-seal temperature is low.

In the packaging field, packaging materials in which a heat seal layer is provided by coating a heat seal resin composition on various plastic film substrates such as polyolefin and polyester are widely used.

For example, Patent Document 1 proposes a resin composition comprising an ethylene-vinyl acetate copolymer, a styrene-butadiene-styrene copolymer, a petroleum resin, and a chlorinated polyolefin resin, with an object of heat seal strength under a low temperature environment. Has been.

However, in patent document 1, both heat seal strength and blocking resistance are insufficient, and further improvement is required.

JP 2013-213110 A

An object of the present invention is to provide a heat-sealable resin composition that is excellent in both heat-sealing strength and blocking resistance and that exhibits good heat-sealing strength even when the heat-sealing temperature is low.

Therefore, as a result of intensive studies to solve the above problems, the binder resin contains an ethylene-vinyl acetate copolymer, a styrene-butadiene-styrene copolymer, a petroleum resin having an acid value of 15 to 30 mgKOH / g, and an organic solvent. It was found that a heat-sealable resin composition characterized in that the heat-seal strength and blocking resistance are both good, and the present invention has been achieved.

That is, the present invention relates to a heat-sealable resin composition containing an ethylene-vinyl acetate copolymer (resin A), a styrene-butadiene-styrene copolymer (resin B), a petroleum resin (resin C), and an organic solvent. The petroleum resin (resin C) relates to a heat-sealable resin composition characterized by being a petroleum resin having an acid value of 15 to 30 mgKOH / g.

Moreover, this invention relates to the heat-sealable resin composition characterized by containing chlorinated polyolefin resin (resin D) further.

Furthermore, the present invention relates to a heat-sealable resin composition, wherein the organic solvent contains an alicyclic hydrocarbon solvent, an ester solvent and an alcohol solvent.

By using a petroleum resin having an acid value as the petroleum resin used in the heat-sealable resin composition, both blocking resistance and heat-seal strength can be achieved.

Hereinafter, the present invention will be described in detail.

The ethylene-vinyl acetate copolymer (resin A) used in the present invention may be a known one, but the vinyl acetate content measured according to JISK6924-1 (1997 edition) is 20 to 40% by weight. It is preferable that If it is 20% by weight or less, the low-temperature stability as the heat-sealable resin composition is inferior, and if it is 40% by weight or more, the heat seal strength is lowered. Moreover, it is preferable that the melt mass flow rate (henceforth, MFR) measured based on JISK6924-1 (1997 edition) is 2-500 g / 10min. When the MFR is 2 g / 10 min or less, the fluidity and solubility as the heat-sealable resin composition are inferior, and when the MFR is 500 g / 10 min or more, it is easily melted by heat and the heat seal strength is lowered.

The ethylene-vinyl acetate copolymer (resin A) may be modified with an unsaturated carboxylic acid and / or a derivative thereof. Examples of the unsaturated carboxylic acid include maleic acid, itaconic acid, fumaric acid, and acrylic acid. Examples of the unsaturated carboxylic acid derivative include maleic anhydride, maleic acid monoester, maleic acid diester, and itaconic acid monoester. Examples thereof include esters, itaconic acid diesters, itaconic anhydride, fumaric acid monoesters, and fumaric acid diesters. Among them, maleic anhydride is preferable because the heat resistance of the obtained ethylene-vinyl acetate copolymer (resin A) resin composition is improved.

The amount of the unsaturated carboxylic acid and / or derivative thereof in the ethylene-vinyl acetate copolymer (resin A) is preferably 0.01 to 2.0% by weight because heat resistance is improved. More preferred is 0.0% by weight.

As the ethylene-vinyl acetate copolymer (resin A), for example, EVAFLEX EV150, EVAFLEX EV250, EVAFLEX EV260, EVAFLEX EV360, EVAFLEX EV460, EVAFLEX EV560 (all manufactured by Mitsui DuPont Polychemical Co., Ltd.) : Commercial name), Ultrasen 640, Ultrasen 680, Ultrasen 681, Ultrasen 710, Ultrasen 720, Ultrasen 722 (all are trade names manufactured by Tosoh Corporation), and the like.

The styrene-butadiene-styrene copolymer (resin B) used in the present invention is a copolymer of styrene and butadiene by anionic polymerization method, cationic polymerization method, coordination polymerization method, radical polymerization method, solution polymerization method, emulsion polymerization method, etc. A known block copolymer or a polymer obtained by hydrogenating these to remove unsaturated double bonds in the polymer chain can be used. For example, Clayton D-1101, Clayton D-1102, Clayton D-1155, Clayton D-KX405, Clayton D-KX408, Clayton D-KX410, Clayton D-KX414, Clayton D-KX65S, Clayton D-KX403P, Clayton D- KX139S, Clayton D-KX155P, Clayton D-1118, Clayton D-1116, Clayton D-1188X, Clayton D-1122X, Clayton D-1300X, Califlex TR-1101S, Califlex TR-1184, Califlex TR-1186, Califlex TR-4113P, Califlex TR-4122P, Califlex TR-4260P (both manufactured by Kraton Polymer Japan Co., Ltd .: trade name), TA Fuprene-A, Tufprene-125, Tufprene-126, Tufprene-315, Sorprene-T-411, Sorprene-T-414, Sorprene-T-416, Sorprene-T-406, Sorprene-T-475, Asaprene-T- 475, Asaprene-T-420, Asaprene-T-430, Asaprene-T-43, Asaprene-T-432, Asaprene-T-436, Tuftec H1002, Tuftec H1041, Tuftec P1500, Tuftec P2000 (all Asahi Kasei Chemicals shares Company name: product name).

The petroleum resin (resin C) used in the present invention is styrene, vinyltoluene, indene, indane, trimethylbenzene contained in the C9 fraction when naphtha is decomposed, and dicyclopentadiene and 1,3-pentadiene in the C5 fraction. Known compounds obtained by polymerizing unsaturated compound components such as cations, anions or radicals can be used. In addition, these petroleum resins may be modified with phenol or maleic acid modified with fluidity.

The acid value of the petroleum resin (resin C) needs to be 15 to 30 mgKOH / g. The acid value was measured according to JISK0070. Examples of commercially available products include Quinton D200 (manufactured by Zeon Corporation) and Neopolymer 160 (manufactured by JX Nippon Mining & Energy Corporation). When a petroleum resin having an acid value of 15 to 30 mg KOH / g is contained, the heat seal strength is good. In the present invention, a petroleum resin having an acid value of 15 to 30 mgKOH / g and a petroleum resin (other petroleum resin) having an acid value other than 15 to 30 mgKOH / g can be mixed and used. When mixing, it is preferable that the average acid value of a mixture is 5-30 mgKOH / g from a viewpoint of heat seal intensity ensuring.

Moreover, it is preferable that the softening point of petroleum resin (resin C) is 100-170 degreeC. When it is 100 ° C. or lower, the blocking resistance is inferior, and when it is 170 ° C. or higher, the blocking property is good, but the activation temperature is increased, so that the heat seal strength is lowered. More preferably, a softening point is 150-170 degreeC.

In the present invention, it is preferable to further contain a chlorinated polyolefin resin (resin D). Examples of chlorinated polyolefin resins include acid-modified chlorinated polyolefin resins such as chlorinated polyethylene resins, chlorinated polypropylene resins, and chlorinated ethylene-propylene copolymers, and acid-modified chlorinated polyolefin resins such as maleic anhydride. Acid-modified chlorinated polyethylene resin, maleic anhydride-modified chlorinated polypropylene resin, and the like can be used.

Moreover, it is preferable that the chlorine content rate of the chlorinated polyolefin resin (resin D) used for this invention is 20 to 40 weight%. If it is 20% by weight or less, the solubility in a solvent is lowered, and printing troubles such as defective transfer are likely to occur.

The solid content weight ratio of the binder resin according to the present invention is as follows: ethylene-vinyl acetate copolymer (resin A) / styrene-butadiene-styrene copolymer (resin B) / petroleum resin (resin C) / chlorinated polyolefin resin ( Resin D) = 20-50 / 10 / 10-30 / 10-40 / 0-50 (total 100%) is preferable. When deviating from this range, the heat seal strength decreases.

Next, organic solvents that can be used in the present invention are mainly cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, cyclooctane and other alicyclic hydrocarbon solvents, n-hexane, n-heptane, n -Aliphatic hydrocarbon solvents such as octane, alcohol organic solvents such as methanol, ethanol, 1-propanol, isopropanol, butanol, ester organic solvents such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, n-hexane And aliphatic hydrocarbon solvents such as n-heptane, n-octane, cyclohexane, methylcyclohexane and ethylcyclohexane, and aromatic hydrocarbon solvents such as toluene and xylene.

However, it is preferable not to use an aromatic hydrocarbon solvent because of the restriction of toluene emission in the working environment. Examples of the organic solvent used in the heat-sealable resin composition in the present invention include alicyclic hydrocarbon solvents, ester solvents. It is preferable to use the solvent or alcohol solvent alone or in combination of two or more.

In the present invention, waxes can be blended as necessary for the purpose of imparting slipperiness when the heat-sealable resin composition is applied to a film and then processed. The type of the wax is not particularly limited, and examples include montan wax, outeraromidoethyl stearate, saturated fatty acid amide, silicon wax and the like. These may be used alone or in combination of two or more.

The heat-sealable resin composition of the present invention is produced by a known method using the above materials. For example, a method of mixing with a tank mixer, a high-speed mixer or the like is common.

The heat-sealable resin composition of the present invention can be printed on various plastic film substrates such as polyolefin and polyester using known gravure printing and coater methods.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to each of these examples. Moreover, the material used for the Example and the comparative example is as follows. In the present invention, “part” means “part by weight” and “%” means “% by weight” unless otherwise specified.

First, the following resin was used for preparation of a heat-sealable resin composition.

Ethylene-vinyl acetate copolymer (resin A)
Resin A1: Ultrasen 720 (manufactured by Tosoh Corporation)

Styrene-butadiene-styrene copolymer (Resin B)
Resin B1: Kraton D-1101 (manufactured by Kraton Polymer Japan Co., Ltd.)

Petroleum resin (Resin C)
Resin C1: Nippon Oil Neopolymer 160 (manufactured by Nippon Mining & Energy Corporation): softening point 165 ° C., acid value 30 mgKOH / g
Resin C2: Quintone D200 (manufactured by Zeon Corporation): softening point 102 ° C., acid value 17 mgKOH / g
Other petroleum resin resins X1: Nisseki Neopolymer 130 (manufactured by Nippon Mining & Energy Corporation): softening point 130 ° C., acid value 0 mgKOH / g
Resin X2: Nisseki Neopolymer 170S (manufactured by Nippon Mining & Energy Corporation): Softening point 160 ° C., acid value 0 mgKOH / g

Chlorinated polyolefin resin (Resin D)
Resin D1: Super Clone 822 (manufactured by Nippon Paper Industries Co., Ltd.): Chlorine content 24.5%, maleic anhydride modified chlorinated polyolefin resin

[Example 1]
4.9 parts of ethylene-vinyl acetate copolymer (resin A1), 2.1 parts of styrene-butadiene-styrene copolymer (resin B1), 4.9 parts of petroleum resin (resin C1), 67.4 parts of methylcyclohexane , 18.0 parts of n-propyl acetate and 2.0 parts of isopropyl alcohol were heated to 50 ° C. and dissolved with stirring, and then 0.4 parts of paraffin wax (trade name: HNP-9 (Nippon Seiwa Co., Ltd.)). Are further mixed so that the resin A, the resin B, the resin C, and the resin D have a solid weight ratio of resin A / resin B / resin C / resin D = 40/20/40/0. A product (H1) was produced.

[Examples 2-8, Comparative Examples 1-2]
A heat-sealable resin composition (H2 to H10) was produced in the same manner as in Example 1 according to the formulation in Table 1.

[Evaluation]
About the heat-sealable resin compositions (H1 to H10) obtained in Examples 1 to 8 and Comparative Examples 1 and 2, a PET film (ester film E5100 thickness 25 μm) was obtained using a gravure proofing machine equipped with a plate depth of 60 μm. Toyobo Co., Ltd.) was overprinted so that the mass after drying was 10 g / m ² or more, and dried at 60 ° C. to obtain a test print. The obtained test prints were evaluated for blocking resistance and heat seal strength (sealing temperatures 100 ° C. and 130 ° C.). The results are shown in Table 2. The evaluation was performed by the following test method.

[Blocking resistance]
The printed matter is cut into a size of 4 cm × 4 cm and overlapped with a plain PET film (Ester film E5100 thickness 25 μm, manufactured by Toyobo Co., Ltd.) cut into the same size. A load of 0.5 kg / cm ² was applied and left for 15 hours in an atmosphere of 50 ° C. and 80% RH, and then the printed surface and the PET film were peeled off, and the degree of removal of the printed film was visually determined.
The judgment criteria were as follows.
◎ ・ ・ ・ No peeling resistance when peeling, very excellent ○ ・ ・ ・ Slightly peeling resistance, but excellent △ ・ ・ ・ There is peeling resistance, but peeling on the printed surface There are no scratches, and there is no problem in practical use .... The printed surface and PET film surface do not peel off, and there is a problem in practical use.

[Heat seal strength]
The heat-seal printed surface of the test print and the plain PET film surface (Ester film E5100 thickness 25 μm, manufactured by Toyobo Co., Ltd.) are overlaid, and a thermal gradient heat sealer (manufactured by Tester Sangyo Co., Ltd.) is used. After heat sealing at 130 ° C. with a pressure of 0.2 MPa and a time of 1 second, a test piece was prepared by cutting to a width of 15 mm. After this test piece was cured for 24 hours in an environment of a temperature of 23 ° C. and a humidity of 50% RH in accordance with JISK6848, it was pulled with a T-type peel tester at a measurement environment temperature condition of 20 ° C. at a peeling speed of 300 mm / min. The strength at which the film peeled was measured as the heat seal strength. (Conforms to JISK6854-3) The measurement was performed on 10 test specimens, the measured value was the average value, and the determination criteria were as follows.
◎ ... 1.5N / 15mm or more ○ ... 1.0N / 15mm or more, less than 1.5N / 15mm △ ... 0.5N / 15mm or more, less than 1.0N / 15mm And)
× ・ ・ ・ less than 0.5N / 15mm

As shown in the results of Table 2, the heat seal resin compositions of Examples 1 to 8 containing a petroleum resin (resin C) having an acid value of 15 to 30 mg KOH / g were compared with those of Comparative Examples 1 and 2. Even when the seal temperature was as low as 100 ° C., good heat seal strength was exhibited. Further, when the chlorinated polyolefin resin (resin D) was included, the blocking resistance and the heat seal strength were further improved.

Claims (3)

Ethylene - vinyl acetate copolymer (resin A), a styrene - butadiene - styrene copolymer (resin B), a petroleum resin (resin C), and heat-sealing resin composition containing the organic solvent, ethylene - The vinyl acetate copolymer (resin A) has a vinyl acetate content of 20 to 40% by weight, a melt mass flow rate of 2 to 500 g / min, and a petroleum resin (resin C) has an acid value of 15 to 30 mgKOH / g. A heat-sealable resin composition, which is a petroleum resin. The heat-sealable resin composition according to claim 1, further comprising a chlorinated polyolefin resin (resin D). The heat-sealable resin composition according to claim 1 or 2, wherein the organic solvent comprises an alicyclic hydrocarbon solvent, an ester solvent, and an alcohol solvent.