Adhesive composition having anti-fogging property

Abstract

The present invention aims to provide an adhesive composition having excellent adhesive property and excellent anti-fogging property by way of simple and easy means such as co-extrusion with a substrate film, extrusion coating, solvent coating, etc. According to the present invention, there is provided an adhesive composition, characterized in that it contains a polyester resin (A) and an anti-fogging agent (C), and satisfies the following requirement (1): (1) Glass transition temperature of the polyester resin (A) is from −30 to 30° C.

Claims

1. An adhesive composition, comprising a polyester resin (A), a polyester resin (B), and an anti-fogging agent (C), wherein the polyester resin (A) is a copolymerized polyester resin consisting of a dicarboxylic acid component and a glycol component, wherein the dicarboxylic acid component comprises an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid in a molar ratio in terms of aromatic dicarboxylic acid:aliphatic dicarboxylic acid of 70:30 to 55:45, the polyester resin (A) satisfies the following requirement (1): (1) Glass transition temperature of the polyester resin (A) is from −30 to 30° C., the polyester resin (B) satisfies the following requirement (2): (2) Glass transition temperature of the polyester resin (B) is from 40 to 82° C., and the adhesive composition comprises 1 to 5 part(s) by mass of the anti-fogging agent (C) to 100 parts by mass of the polyester resin (A).

2. The adhesive composition according to claim 1, wherein the anti-fogging agent (C) is a nonionic surfactant.

3. A laminated film, which is prepared by laminating an adhesive layer comprising the adhesive composition according to claim 1 and a thermoplastic resin film.

4. The laminated film according to claim 3, wherein the thermoplastic film is a polyester resin film.

5. The laminated film according to claim 3, wherein a thickness of the adhesive layer is from 1 to 10 μm.

6. A packaging material, comprising the laminated film according to claim 5 as a constituting member.

7. A covering material for a food packaging container, comprising the packaging material according to claim 6 as a constituting member.

8. A food packaging container, which is prepared by laminating the covering material according to claim 7 and a polyester resin.

Description

EXAMPLES

(1) The present invention will now be illustrated in more detail by referring to Examples although the present invention is not limited thereto. The term simply reading “part (s)” in Examples and Comparative Examples stands for “part (s) by mass”.

(2) (Methods for Evaluating Physical Properties)

(3) Melting Point of Crystals and Glass Transition Temperature

(4) A sample (polyester resin (A) or polyester resin (B)) (5 mg) was tightly sealed in a container of an aluminum pushing cover type using a differential scanning calorimetric analysis meter (DSC) (DSC-220 manufactured by Seiko Instruments). Measurement was conducted at a temperature-raising rate of 20° C. per minute from −100° C. to 250° C. and the highest peak temperature of heat of fusion was determined as a melting point of crystals. Further, glass transition temperature was determined by a temperature at a crossing point of an extended line of a base line being lower than the glass transition temperature with a tangent showing the highest inclination between an initial part of the peak and a top of the peak, using the above measuring device under the same condition.

(5) Preparation of Laminated Film for Evaluation

(6) The adhesive composition prepared in Examples and Comparative Examples were coated to a corona-treated surface of a polyester film (E 5107 manufactured by Toyobo) of 25 μm thickness so that a thickness after drying was made 3 g/cm.sup.2. After that, it was dried at 160° C. for 30 seconds to give a laminated film for evaluation.

(7) (1) Peeling Strength (Adhesiveness)

(8) A side of the adhesive layer of the laminated film for evaluation was heat-sealed to an amorphous polyester sheet (A-PET sheet manufactured by Toyobo) of 350 μm thickness at 130° C. temperature and 2.8 kgf/cm.sup.2 pressure for 1 second. After that, a test piece of 25 mm width was cut out therefrom and subjected to a 180° peeling test at 25° C. with a tensile speed of 100 mm per minute whereupon the peeling strength was measured.

Evaluating Criteria

(9) ∘∘: 1000 gf/25 mm or more

(10) ∘: 800 gf/25 mm or more and less than 1000 gf/25 mm

(11) Δ: 500 gf/25 mm or more and less than 800 gf/25 mm

(12) x: less than 500 gf/25 mm

(13) (2) Anti-Fogging Property at 60° C.

(14) Water of 60° C. (30 ml) was charged in a container of 70 cm.sup.3 volume. The side of the adhesive layer of the laminated film was placed on a mouth of the container followed by covering with a rubber band. After that, it was stored for one hour in a constant-temperature bath of 60° C. The anti-fogging effect was confirmed by naked eye according to the following judging criteria.

Evaluating Criteria

(15) ∘: Continuous water film was formed on a surface of the film and visibility was good.

(16) Δ: Although water drops were partially stuck on the surface of the film, the visibility was good.

(17) x: Water drops were stuck on the surface of the film or the visibility became bad.

(18) (3) Anti-Fogging Property at 5° C.

(19) Water of ordinary temperature (30 ml) was charged in a container of 70 cm.sup.3 volume. The side of the adhesive layer of the laminated film was placed on a mouth of the container followed by covering with a rubber band. After that, it was stored for one day in a constant-temperature bath of 5° C. The anti-fogging effect was confirmed by naked eye according to the following judging criteria.

Evaluating Criteria

(20) ∘: Continuous water film was formed on a surface of the film and visibility was good.

(21) Δ: Although water drops were partially stuck on the surface of the film, the visibility was good.

(22) x: Water drops were stuck on the surface of the film or the visibility became bad.

(23) (4) Anti-Blocking Property

(24) The side of the adhesive layer of the laminated film for evaluation was laid on a surface of the polyester film (E5107 manufactured by Toyobo) being untreated with corona whereupon a test sample was prepared. After that, the sample was stored for one day at 40° C. under a pressure of 0.9 kgf/cm.sup.2. The anti-blocking property was confirmed according to the following judging criteria.

Evaluating Criteria

(25) ∘: There was entirely no tack in the test sample.

(26) Δ: Although a slight tack was noted in the test sample, it was within an extent of causing no problem in an actual use.

(27) x: Tack was noted in the test sample and it was within an extent of causing problems in the actual use.

(28) Examples of Polyester Resin (A)

(29) Synthesis of Polyester Resin (A-1)

(30) Into a reactor equipped with a stirrer, thermometer, heating heater, cooling device and cooler for distillation, there were charged 445 parts by mass of terephthalic acid, 74 parts by mass of isophthalic acid, 270 parts by mass of sebacic acid, 277 parts by mass of ethylene glycol, 465 parts by mass of propylene glycol and 0.5 part by mass of tetrabutyl titanate. Temperature was raised up to 230° C. Esterification reaction was conducted during 4 hours. After completion of the transesterification, a reaction system was made vacuum down to 10 torr during 60 minutes together with raising the temperature thereof up to 250° C. After that, the pressure was made into vacuum to an extent of 1 torr or lower and polycondensation was conducted for 60 minutes at 250° C. After that, nitrogen was flown into the reaction system to conduct vacuum break whereby the polycondensation reaction was finished. After finishing the reaction, the resulting polyester resin was taken out and cooled to give the polyester resin (A-1).

(31) Examples of Polyester Resin (B)

(32) Synthesis of Polyester Resin (B-1)

(33) Into a reactor equipped with a stirrer, thermometer, heating heater, cooling device and cooler for distillation, there were charged 455 parts by mass of dimethyl terephthalate, 455 parts by mass of dimethyl isophthalate, 291 parts by mass of ethylene glycol, 488 parts by mass of 2,2-dimethyl-1,3-propanediol and 0.5 part by mass of tetrabutyl titanate. Temperature was raised up to 240° C. Esterification reaction was conducted during 4 hours. After completion of the transesterification, a reaction system was made vacuum down to 10 torr during 60 minutes together with raising the temperature thereof up to 250° C. After that, the pressure was made into vacuum to an extent of 1 torr or lower and polycondensation was conducted for 60 minutes at 250° C. After that, nitrogen was flown into the reaction system to conduct vacuum break whereby the polycondensation reaction was finished. After finishing the reaction, the resulting polyester resin was taken out and cooled to give the polyester resin (B-1).

(34) Synthesis of Polyester Resins (A-2) to (A-5) and (B-2) to (B-4)

(35) Similar to the synthetic example of the polyester resin (A-1), polyester resins (A-2) to (A-5) were synthesized. Similar to the synthetic examples of the polyester resin (B-1), polyester resins (B-2) to (B-4) were synthesized. Results of measurement of the resin properties are shown in Table 1.

(36) TABLE-US-00001 TABLE 1 polyester resin (% by mol) A-1 A-2 A-3 A-4 A-5 B-1 B-2 B-3 B-4 components polyvalent carboxylic terephthalic 60 35 45 70 46 50 100 45 30 acid components acid isophthalic acid 10 20 15 38 50 45 70 adipic acid 45 sebacic acid 30 40 30 16 10 polyhydric alcohol ethylene glycol 50 30 30 75 50 30 50 components propylene glycol 70 70 70 50 2,2-dimethyl-1,3- 50 25 50 50 propanediol 1,4-butanediol 100 50 physical η sp/c (dl/g) 1.0 0.9 1.0 0.6 0.8 0.6 0.6 0.6 0.4 property number-average 30000 30000 30000 17000 32000 17000 18000 16000 12000 molecular weight Mn acid value (mgKOH/g) 2 2 1 1 2 2 3 2 2 Tg (° C.) 10 −20 −5 16 32 67 82 47 38 Tm (° C.) 96

(37) As to the anti-fogging agent (C), nonionic surfactants [Rikemal (registered trade mark) manufactured by Riken Vitamin] DO-100V, A and OL-100E were used.

(38) As to the anti-blocking agent, SYLOID (registered trade mark) C 812 (amorphous silica manufactured by GRACE) was used.

Example 1

(39) Polyester resin (A-1) (80 parts by mass), 20 parts by mass of polyester resin (B-1), 5 parts by mass of the anti-fogging agent (C) and 1 part by mass of the anti-blocking agent were heated/stirred in an MEK solution to prepare an adhesive composition 1. Compounding amount, peeling strength, anti-fogging property and anti-blocking property are shown in Table 2.

Examples 2 to 13

(40) The polyester resin, anti-fogging agent and anti-blocking agent were changed as shown in Table 2 and then Examples 2 to 13 were conducted according to the same method as in Example 1. Peeling strength, anti-fogging property and anti-blocking property are shown in Table 2.

(41) TABLE-US-00002 TABLE 2 Example Example Example Example Example Example Example 1 2 3 4 5 6 7 polyester resin A-1 80 80 60 60 80 (A) (Tg = 10° C.) (parts by mass) A-2 80 (Tg = −20° C.) A-3 10 (Tg = −5° C.) A-4 80 (Tg = 16° C.) A-5 (Tg = 32° C.) polyester resin B-1 20 30 (B) (Tg = 67° C.) (parts by mass) B-3 20 20 40 (Tg = 82° C.) B-4 20 (Tg = 47° C.) B-5 20 (Tg = 38° C.) anti-fogging DO-100V 5 5 5 5 5 5 5 agent (C) A (parts by mass) OL-100E anti-blocking agent (D) 1 1 1 1 1 1 (parts by mass) peeling peeling strength 1000 800 1200 800 680 600 1200 strength [gf/25 mm] evaluation ∘∘ ∘ ∘∘ ∘ Δ Δ ∘∘ anti-fogging anti-fogging ∘ ∘ ∘ ∘ ∘ ∘ ∘ property property at 60° C. anti-fogging ∘ ∘ ∘ ∘ ∘ ∘ ∘ property at 5° C. anti-blocking evaluation ∘ ∘ Δ ∘ ∘ Δ x property Example Example Example Example Example Example 8 9 10 11 12 13 polyester resin A-1 100 80 80 80 80 80 (A) (Tg = 10° C.) (parts by mass) A-2 (Tg = −20° C.) A-3 (Tg = −5° C.) A-4 (Tg = 16° C.) A-5 (Tg = 32° C.) polyester resin B-1 20 20 20 20 (B) (Tg = 67° C.) (parts by mass) B-3 (Tg = 82° C.) B-4 20 (Tg = 47° C.) B-5 (Tg = 38° C.) anti-fogging DO-100V 5 5 1 20 agent (C) A 5 (parts by mass) OL-100E 5 anti-blocking agent (D) 1 1 1 1 1 1 (parts by mass) peeling peeling strength 600 1200 900 600 500 800 strength [gf/25 mm] evaluation ∘ ∘∘ ∘ Δ Δ ∘ anti-fogging anti-fogging ∘ ∘ Δ ∘ ∘ ∘ property property at 60° C. anti-fogging ∘ ∘ Δ ∘ ∘ ∘ property at 5° C. anti-blocking evaluation x Δ ∘ x ∘ ∘ property

Comparative Examples 1 to 3

(42) The polyester resin, anti-fogging agent and anti-blocking agent were changed as shown in Table 3 and then Comparative Examples 1 to 3 were conducted according to the same method as in Example 1. Peeling strength, anti-fogging property and anti-blocking property are shown in Table 3.

(43) TABLE-US-00003 TABLE 3 Comparative Comparative Comparative Example 1 Example 2 Example 3 polyester resin A-1 80 (A) (Tg = 10° C.) (parts by mass) A-2 (Tg = −20° C.) A-3 (Tg = −5° C.) A-4 (Tg = 16° C.) A-5 80 (Tg = 32° C.) polyester resin B-1 20 20 (B) (Tg = 67° C.) (parts by mass) B-3 (Tg = 82° C.) B-4 100 (Tg = 47° C.) B-5 (Tg = 38° C.) anti-fogging DO-100V 5 5 agent (C) A (parts by mass) OL-100E anti-blocking agent (D) 1 1 1 (parts by mass) peeling strength peeling strength 200 900 200 [gf/25 mm] evaluation x ∘ x anti-fogging anti-fogging ∘ x ∘ property property at 60° C. anti-fogging ∘ x ∘ property at 5° C. anti-blocking evaluation ∘ ∘ ∘ property

(44) As will be clear from Table 2, Examples 1 to 6, 9, 12 and 13 exhibit anti-fogging property and anti-blocking property in spite of the fact that they exhibit excellent adhesive property as an adhesive agent. Further, Examples 7, 8 and 11 exhibit excellent adhesive property and anti-fogging property in spite of the fact that they are inferior in the anti-blocking property. Furthermore, Example 10 exhibits excellent adhesive property and anti-blocking property in spite of the fact that the anti-fogging property lowers. On the contrary, in Comparative Example 1, the polyester resin A exhibits high glass transition temperature whereby the peeling strength is low. In Comparative Example 2, no anti-fogging agent is compounded whereby the anti-fogging property is inferior. In Comparative Example 3, no polyester resin A is compounded whereby the peeling strength is low.

INDUSTRIAL APPLICABILITY

(45) The adhesive composition and the laminated film using the same in accordance with the present invention exhibit excellent adhesive property to the substrate when they are used in the covering material for the packaging container, and being subjected to a heat sealing. They also have anti-blocking property. Moreover, due to good anti-fogging property thereof, they can be advantageously used as the packaging materials for the perishable foods, etc.