JP2005120257A - Sealing resin composition and laminate, lid material and blister pack each using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing material and a lid material enabling heat sealing at low temperatures on a polyester product such as a polyester plate or polyester container and excellent in easy peelability. <P>SOLUTION: The sealing resin composition comprises (A) a noncrystalline polyester with a glass transition temperature of ≥40°C but lower than 100°C and (B) at least one noncrystalline resin selected from the group consisting of a polyester, polyurethane, acrylic resin and epoxy resin. In this composition, the specific gravity difference at 30°C between the noncrystalline polyester A and the noncrystalline resin B is ≥0.05 but less than 0.40, and the mass ratio A/B is (99:1) to (50:50). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plastic plate or a plastic container, particularly a polyester plate or a polyester container called amorphous polyethylene terephthalate (hereinafter sometimes abbreviated as A-PET) or polyethylene naphthalate (sometimes abbreviated as PEN). The present invention relates to a sealing resin composition suitable as an easy peel sealing material that can be easily peeled off when being peeled off while being capable of heat sealing at low temperatures. The present invention also relates to a laminate of the resin composition and a substrate, and a lid for heat sealing with a polyester product such as a polyester plate or a polyester container.

  Tray-shaped or cup-shaped molded products obtained by thermoforming or injection-molding plastic sheets such as polypropylene, polyethylene terephthalate, polystyrene, polycarbonate, polyvinyl chloride, etc. are widely used as food and beverage containers. Yes. In general, when the contents are hermetically packaged in such a plastic container, the container is filled with the contents, and then the lid material and the plastic container are heat sealed. At that time, if the heat seal temperature is high, the plastic container may be deformed, or the heat seal portion may become thin and the contents may leak, so a seal material that can be heat sealed at a low temperature is required. Further, if the sealing strength is too strong, it is difficult to peel off the lid by hand, so that it is necessary to open the lid. That is, as a sealing material having an easy peel property, it is necessary to be able to seal at a low temperature and to maintain an appropriate sealing strength. Specifically, the seal strength is desirably 4 to 20 N / 10 mm.

  On the other hand, polyolefins such as polypropylene have been widely used as plastics for food containers. However, the taste and scent of food may change due to the adsorption of odor components of food, and the odor peculiar to polyolefins. There is a problem that the original flavor of food is lost. Therefore, recently, in order to improve this point, there is a movement to use a food container made of a plastic having a good flavor property such as polyethylene terephthalate.

  As a conventional invention as a sealing material for a lid for a polyester container, Patent Document 1 uses two types of polyester resins, and one is applied to the entire surface and the other is applied to a part such as a mesh. However, it was difficult to put into practical use from the viewpoint of cost. Further, Patent Document 2 proposes a lid material excellent in easy peelability by blending a polyethylene-based resin with polyester, but the flavor property is not good because a large amount of polyethylene resin is used. Further, Patent Document 3 proposes a lid material in which crystalline polyester and a high melting point resin are blended. However, since it is crystalline, it has no solvent solubility and can be used to produce a laminate with an inexpensive solution coat. It was difficult.

JP-A-4-18268 JP 59-59444 A JP 2000-1664 A

  The object of the present invention is to solve the problems of the conventional easy peel seal material, and at least selected from the group consisting of polyester, polyurethane, acrylic and epoxy having a specific difference in specific gravity to polyester having a specific glass transition temperature. By using a blend of one type of amorphous resin, it is possible to heat-seal polyester products such as polyester plates and polyester containers at a low temperature, and to provide a sealing material and a lid material excellent in easy peel properties. That is.

  That is, this invention is the following resin compositions for sealing, and a laminated body and lid | cover material using the same.

(1) A seal containing an amorphous polyester (A) having a glass transition temperature of 40 ° C. or higher and lower than 100 ° C., and at least one amorphous resin (B) selected from the group consisting of polyester, polyurethane, acrylic and epoxy. Difference in specific gravity at 30 ° C. between the amorphous polyester (A) and the amorphous resin (B) of 0.05 or more and less than 0.40, the amorphous polyester (A) / non-resin Crystalline resin (B) contains by 99/1-50/50 (mass ratio), The resin composition for sealing characterized by the above-mentioned.

(2) A laminate comprising the sealing resin composition according to (1) laminated on a substrate.

(3) A lid material using the laminate according to (2).

(4) The lid material according to (3), which is heat sealed to a polyester product.

(5) A blister pack using the laminate according to (2).

(6) The blister pack according to (5), which is heat sealed to a polyester product.

  The sealing resin composition of the present invention having the above constitution and the lid material using the same are excellent in both low-temperature heat sealing properties and easy peel properties and excellent in flavor properties, and are particularly useful as a sealing material for polyester products. It is. For example, it can be expected to be used as a blister pack for packaging toothbrushes, batteries, and the like, and as a lid for food packaging containers.

  Embodiments of the resin composition for sealing and the lid material of the present invention will be described in detail. The glass transition temperature of the amorphous polyester (A) used in the resin composition of the present invention is 40 ° C. or higher, preferably 50 ° C. or higher. When the glass transition temperature is less than 40 ° C., the flavor may be deteriorated, resulting in a problem that the flavor of the contents changes. The upper limit is desirably less than 100 ° C. If the temperature exceeds 100 ° C., the sealing temperature increases, which may cause deformation of the base material or the polyester product.

  Amorphous polyester (A) preferably does not show a clear melting point. Those having a melting point are poor in solvent solubility, so that the storage stability of the solution and the suitability for application to a substrate are deteriorated, which may impair workability. In addition, it does not show clear melting | fusing point, using a differential scanning calorimeter (DSC), it heated up at -20 degreeC / min from -100 degreeC to 300 degreeC, and then to -100 degreeC at 50 degreeC / min. It is assumed that no clear melting peak is shown in either temperature rising process in the two temperature rising processes in which the temperature is lowered and subsequently raised from −100 ° C. to 300 ° C. at 20 ° C./min.

  The number average molecular weight of the amorphous polyester (A) is usually preferably about 1000 to 30000 from the viewpoint of low temperature sealability.

Although it does not specifically limit as a copolymerization component of amorphous polyester (A), For example, terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, Known materials such as decanoic acid, dimer acid, cyclohexanedicarboxylic acid, hydrogenated phthalic anhydride, trimellitic acid and the like can be used. Among these, those obtained by copolymerizing isophthalic acid are preferable in terms of cost, versatility, and solubility in a solvent. A preferable copolymerization amount of isophthalic acid is 15 mol% or more when the total acid component is 100 mol%.
Polyhydric alcohol components include ethylene glycol, butanediol, propylene glycol, diethylene glycol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,5-pentanediol, and 3-methyl-1,5-pentane. Diol, hexanediol, nonanediol, cyclohexanedimethanol, dimer diol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, trimethylolpropane and the like can be used. Among these, those obtained by copolymerizing neopentyl glycol are preferable in terms of cost, versatility, and solubility in a solvent. The preferable copolymerization amount of neopentyl glycol is 15 mol% or more when the total glycol component is 100 mol%.

  Examples of the amorphous resin (B) used in the sealing resin composition of the present invention include polyester, polyurethane, acrylic and epoxy. Here, the difference in specific gravity at 30 ° C. between the amorphous polyester (A) and the amorphous resin (B) is 0.05 or more, preferably 0.06 or more, more preferably 0.07 or more. If it is less than 0.05, the compatibility becomes good, and as a result, the easy peel property may be impaired. The upper limit is preferably less than 0.40. A preferred lower limit is 0.30, more preferably 0.25. If it exceeds 0.40, the compatibility is deteriorated, so that the sealing strength may be lowered. To adjust the specific gravity of the resin, for example, to make a resin with a low specific gravity, use raw materials with side chains, select an aliphatic component over an aromatic component, increase the molecular weight per repeating unit, etc. It can be done in a well-known manner. As polyester, commercially available products such as Byron manufactured by Toyobo Co., Ltd., Epicoat of Japan Epoxy Resin Co., Ltd. as epoxy, and Aron manufactured by Toagosei Co., Ltd. can be used as acrylic.

  Polyester is particularly preferable as the amorphous resin (B). Polyester has almost no residual monomer, and when used as a lid for food containers, the resin odor does not transfer to food. The glass transition temperature of the polyester is preferably 30 ° C or higher and lower than 90 ° C. If it is less than 30 degreeC, the problem of the blocking at the time of film winding may arise, and when 90 degreeC is exceeded, the fall of sealing strength may be caused.

  The compounding ratio of the amorphous polyester (A) / amorphous resin (B) used in the sealing resin composition of the present invention is desirably in the range of 99/1 to 50/50% by mass. Moreover, Preferably it is 98 / 2-60 / 40 mass%, More preferably, it is 97 / 3-65 / 35 mass%. When the blending amount of the amorphous polyester (A) is less than 50%, the sealing strength becomes too low, and there is a concern that the amorphous polyester (A) may be peeled off even with a slight vibration. On the other hand, if it exceeds 99%, the sealing strength becomes too high, and it is difficult to peel off by hand, and the easy peel property may be lowered.

  As a method for measuring the seal strength of the lid member of the present invention, the following method is used. After a sealing material layer was laminated on the corona discharge-treated surface of a 50 μm biaxially stretched polyethylene terephthalate film (E1501 manufactured by Toyobo Co., Ltd.), combined with 500 μm A-PET (heat seal tester TP-701 manufactured by Tester Sangyo Co., Ltd.) After bonding together under conditions of 140 ° C. × 196 kPa × 2 seconds, T-type peeling is performed with a tensile tester at a speed of 100 mm / min. The value at which the easy peel property is good as the seal strength at this time is in the range of 4 to 20 N / 10 mm, preferably 6 to 15 N / 10 mm. When the seal strength exceeds 20 N / 10 mm, it becomes difficult for a person or child who has no power to open, and it is necessary to cut it with a knife or the like. In some cases, the biaxially stretched polyethylene terephthalate film itself, which is a base material, is destroyed, and the lid may be torn. On the other hand, if the seal strength is less than 4 N / 10 mm, the lid may be opened carelessly due to vibration during transportation.

  The sealing resin composition of the present invention can be directly melt-extruded on a base material, for example, a plastic film such as a polyethylene terephthalate film, a metal foil such as aluminum, or paper, etc. After the resin used for the easy peel seal material of the invention is formed into a film in advance, it can be laminated on the above-mentioned substrate using another appropriate known adhesive, but it is dissolved in a solvent and applied and dried. The method is simple and preferred.

  The laminate containing the sealing resin composition of the present invention can be used for general heat sealing, but is particularly suitable as an easy peel material for polyester products such as polyester plates or polyester containers. The polyester product is preferably A-PET, PEN, or PBT (polybutylene terephthalate), but is also useful for a copolyester sheet. The copolyester is not particularly limited, but terephthalic acid / isophthalic acid // ethylene glycol copolymer, terephthalic acid // ethylene glycol / cyclohexanedimethanol copolymer, terephthalic acid // ethylene glycol / neopentyl glycol A copolymer, terephthalic acid // ethylene glycol / diethylene glycol copolymer and the like are preferable in terms of cost and versatility.

  Although the thickness of the sealing layer in the lid | cover material of this invention can be arbitrarily defined by a use, it is about 3-50 micrometers normally. Moreover, although the thickness of a lid | cover material can also be arbitrarily defined by a use, it is about 20-150 micrometers normally.

  In order to describe the present invention in more detail, examples are given below, but the present invention is not limited to the examples. In addition, the measured value described in the Example is measured by the following method.

  Glass transition temperature: It was measured with a DSC220 model manufactured by Seiko Denshi Kogyo Co., Ltd., at a heating rate of 20 ° C./min. 10 mg of a measurement sample was put in an aluminum pan, and the lid was pressed and sealed to measure.

  Specific gravity: The resin was cut into 3 mm × 3 mm × 3 mm cubes (measured as they were when pellets were used) and measured in an aqueous calcium chloride solution adjusted to 30 ° C. After adjusting the concentration of calcium chloride so that the resin stays in the middle from the liquid surface to the bottom of the aqueous solution, the specific gravity of the aqueous calcium chloride solution was measured with a hydrometer to obtain the specific gravity of the resin.

  Seal strength: A 40 μm sealing material layer was laminated on 50 μm biaxially stretched PET, and then combined with 300 μm A-PET, and then heat sealed using a heat seal tester manufactured by Tester Sangyo Co., Ltd. The heat sealing was performed at a temperature of 140 ° C., a pressure of 196 kPa, and a time of 2 seconds. As for the seal strength, T-type peel adhesion was measured at a pulling speed of 100 mm / min using an RTM-100 tensile tester manufactured by Toyo Baldwin. A seal strength of 4 to 20 N / 10 mm was judged good, and the others were judged bad.

Peeling feeling: The peeling feeling when the sample sealed by the above method was peeled by hand was evaluated according to the following criteria.
◎: Sticky peeling feeling ○: Good peeling feeling ×: The peeling feeling is too strong or too weak

  As amorphous polyester (A), the following grades of Byron manufactured by Toyobo Co., Ltd. were used. Specific gravity is shown in Table 1.

  As the amorphous resin (B), Toyobo Co., Ltd. Byron, Toagosei Co., Ltd. Aron S2060, Japan Epoxy Resin / Epicoat 1004 were used. Specific gravity is shown in Table 2.

Example 1
I (97 parts by mass) as amorphous polyester (A) and II (3 parts by mass) as amorphous resin (B) in a solvent of methyl ethyl ketone / toluene = 50/50 (mass ratio) with a solid content concentration of 30% It dissolved so that it might become. Subsequently, it apply | coated so that the thickness after drying might be set to 40 micrometers on 50 micrometers biaxially-stretched PET, and it dried for 30 minutes at 120 degreeC. Next, the seal strength and the feeling of peeling were measured by the above-described methods.

Examples 2-7, Comparative Examples 1-3
Evaluation was performed in the same manner as in Example 1 with the formulations shown in Tables 3 and 4. The results are shown in Tables 3 and 4.

  According to Table 3, all of the resin compositions of Examples 1 to 7 have a sealing strength in an appropriate range of 4 to 20 N / cm and a good feeling of peeling. According to Table 4, the resin compositions of Comparative Examples 1 to 3 have problems that the sealing strength is too strong or too weak and the feeling of peeling is poor.

  According to the easy peel seal material of the present invention and the cover material laminated therewith, both the low-temperature heat sealability and the easy peel property are excellent.

Claims (6)

  Sealing resin composition comprising amorphous polyester (A) having a glass transition temperature of 40 ° C. or more and less than 100 ° C., and at least one amorphous resin (B) selected from the group consisting of polyester, polyurethane, acrylic and epoxy The difference in specific gravity at 30 ° C. between the amorphous polyester (A) and the amorphous resin (B) is 0.05 or more and less than 0.40, and the amorphous polyester (A) / noncrystalline resin (B) contains 99/1-50/50 (mass ratio), The resin composition for sealing characterized by the above-mentioned.   A laminate comprising the sealing resin composition according to claim 1 laminated on a substrate.   The lid | cover material using the laminated body of Claim 2.   The lid material according to claim 3, which is heat-sealed to a polyester product.   A blister pack using the laminate according to claim 2.   The blister pack according to claim 5, wherein the blister pack is heat-sealed to a polyester product.