JPH06240117A - Polyester resin composition for food packaging film - Google Patents

Abstract

PURPOSE:To obtain a resin composition for food packaging films, having self tackiness, sufficient heat resistance to heating in microwave ovens, excellent in cuttability and barrier properties for smell and further environmental suitability. CONSTITUTION:This polyester resin composition is obtained by blending (A) 100 pts.wt. polyester resin with (B) 1-15 pts.wt. glycerol ester compound prepared by esterifying one of three hydroxyl groups in glycerol with a 4-30C aliphatic monocarboxylic acid and acetylating at least one hydroxyl groups thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is excellent in self-adhesiveness in a wide temperature range from low temperature to high temperature required for food packaging film, and also excellent in heat resistance, cutting property and transparency, and at the time of incineration treatment. The present invention relates to a polyester resin composition for a food packaging film having properties such as not generating toxic gas, and a food packaging film formed by molding the polyester resin composition.

[0002]

2. Description of the Related Art Conventionally, when food is put in a container and stored in a refrigerator or the like,
As a food packaging film, a film mainly composed of polyvinylidene chloride resin, polyvinyl chloride or the like or a low density polyethylene film is widely used. They are,
This is because the container is hermetically sealed by utilizing the self-adhesiveness, transparency, flexibility and the like of the film, and it is possible to mainly prevent the foodstuffs during storage from drying. The properties required for a film for food packaging include, in addition to the self-adhesiveness described above, cutting property with a saw blade when cutting to a required size for packaging foods, strength in a packaged state, and transparency. This is a basic one, and recently, with the widespread use of microwave ovens, there has been a strong demand for food packaging films that are suitable for microwave ovens and have excellent heat resistance. However, currently used polyvinylidene chloride film,
As can be easily seen from the chemical structure of films such as polyvinyl chloride, since they have chlorine atoms in the polymer skeleton, the presence of hydrogen chloride gas generated when incinerating waste after use is present. Toxicity is pointed out, and it is not preferable to use the above-mentioned film as a food packaging film having a short use cycle from the viewpoint of environmental protection. on the other hand,
The low-density polyethylene film has the disadvantage that it is easily broken because it is too weak in packaging and that the film is broken by heat when used in a microwave oven. Further, a copolymer of ethylene and α-olefin, which is generally referred to as a polyolefin film, or a film obtained by blending polypropylene in the copolymer, has insufficient heat resistance in a microwave oven, and has a barrier against odor of contents. It is not preferable because it has the disadvantage of being poor in performance. In recent years, a polyester film has been developed as a similar food packaging film, and a polyethylene terephthalate resin (hereinafter PET), which is a typical polyester resin, is generally used.
Polybutylene terephthalate resin (hereinafter abbreviated as PBT resin) is heat-resistant and oil-resistant by stretching in the case of a PET resin film and in the case of a PBT resin film with or without stretching. sex,
It has excellent chemical resistance and barrier against odor of contents. However, when the polyester resin is directly used as a film, there is a drawback that the most important property as a food packaging film is inferior in self-adhesiveness,
The reality is that it has not yet been put to practical use.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its object is to produce no toxic gas at the time of disposal by incineration, that is, it is excellent in environmental suitability and food. It is an object of the present invention to provide a food packaging film which has self-adhesiveness required for a packaging film, has sufficient heat resistance against microwave heating, and has excellent cutting properties and odor barrier properties.

The present inventors have made intensive studies to solve the above problems and provide an ideal food packaging film, and as a result, blended a specific glycerin ester compound with a polyester resin in a specific range amount. We have found that a film made of the composition satisfies all the above-mentioned required properties and is extremely excellent as a food packaging film, and completed the present invention. That is, the present invention is (A) polyester resin 100
1 part by weight of (B) three hydroxyl groups of glycerin is esterified with an aliphatic monocarboxylic acid having 4 to 30 carbon atoms in the weight part, and at least one hydroxyl group is acetylated glycerin ester compound 1 to A polyester resin composition for a food packaging film containing 15 parts by weight, and a food packaging film obtained by molding the polyester resin composition.

The polyester resin (A) used in the present invention is preferably a polyester having a melting point peak value of 170 ° C. or higher. A film using a polyester resin having a melting point peak value of less than 170 ° C. may have insufficient heat resistance when the food packaged with the food packaging film is heated in a microwave oven, and particularly the melting point peak value is 18
From the viewpoint of heat resistance, it is preferable to use a polyester resin having a temperature of 0 ° C. or higher. From this point of view, what is preferable as the polyester resin used in the present invention is that the acid component constituting the polyester is mainly a terephthalic acid residue and the diol component is mainly a 1,4-butanediol residue and / or
Alternatively, the polyester resin is an ethylene glycol residue. If the melting point peak value satisfies the above range,
Copolyesters can be used. As the acid component of the copolymerization component, an aliphatic dicarboxylic acid represented by succinic acid, glutaric acid, adipic acid, piperic acid, suberic acid, azelaic acid, sebacic acid, dodecane diacid, dimer acid, or isophthalic acid. , Phthalic acid,
Aromatic dicarboxylic acids typified by 2,6-naphthalenedicarboxylic acid and the like, and trimesic acid, trimellitic acid and the like can be used as the branching component. Further, one or more kinds of these copolymerization components may be used. Further, as the diol component among the copolymerization components, ethylene glycol,
1,3-propanediol, 1,4-butanediol,
1,3-butanediol, 1,5-pentanediol,
Neopentyl glycol, 1,6-hexanediol,
1,7-heptanediol, 1,10-decanediol,
Aliphatic / alicyclic diols exemplified by cyclohexanediol or the like, polyglycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol or the like, and aromatic diols exemplified by bisphenol A and ethoxylated bisphenol S, branched components For example, pentaerythritol or the like may be used. Also, as long as the performance of the polyester resin is not greatly changed, 1 represented by 4-hydroxybenzoic acid
A component having a hydroxyl group and a carboxylic acid group in one molecule may be used as a copolymerization component. Further, the polyester resin used in the present invention is not limited by the production method thereof, and a so-called direct polycondensation method in which an acid component and a diol component are esterified by a dehydration reaction and then condensed may be used. The dicarboxylic acid moiety may be obtained by a transesterification method using methyl ester, ethyl ester, butyl ester and a diol component as starting materials. On the other hand, the intrinsic viscosity of the polyester resin used in the present invention is 0.4-1.
The range of 5 is preferable, and the range of 0.6 to 1.4 is particularly preferable.

Next, the details of the (B) glycerin ester compound used in the present invention will be explained. The glycerin ester compound used in the present invention is one in which one of three hydroxyl groups of glycerin is esterified with an aliphatic monocarboxylic acid having 4 to 30 carbon atoms and at least one hydroxyl group is acetylated. Is. When two or more hydroxyl groups of glycerin are free, the affinity for the polyester resin is remarkably deteriorated, and bleedout of numerous additives from the composition pellets occurs during predrying before film formation. Also, one of the hydroxyl groups of glycerin is necessarily esterified with an aliphatic monocarboxylic acid having 4 to 30 carbon atoms. The ester-forming portion is particularly preferably an aliphatic monocarboxylic acid having 10 to 30 carbon atoms, such as lauric acid ester, stearic acid ester, oleic acid ester, and montanic acid ester. Specific examples of the glycerin ester compound that can be used in the present invention,
Examples thereof include glycerin monoacetomonolaurate, glycerin diacetomonolaurate, glycerin monoacetomonostearate, glycerin diacetomonooleate, and glycerin monoacetomonomontanate. The glycerin ester compound used in the present invention may be used alone or in combination of two or more. A film made of a composition in which a glycerin ester compound having the above structure is mixed with a polyester resin is extremely effective for exhibiting self-adhesiveness as a food packaging film without impairing the inherent characteristics of the polyester resin. The amount of the (B) glycerin ester compound added to the (A) polyester resin is 1 to 15 parts by weight, preferably 2 to 12 parts by weight, and more preferably 2 to 12 parts by weight, based on 100 parts by weight of the (A) polyester resin. It is preferably 3 to 10 parts by weight. If the content of the glycerin ester compound is less than 1 part by weight, it is not preferable because the self-adhesiveness of the film made of the composition cannot be obtained, and if it exceeds 15 parts by weight, bleeding of copious additives from the composition film occurs. This is not preferable because not only is the filming caused by vigorous blocking of the film, it becomes difficult to wind it during film formation, but also the film itself becomes extremely sticky.

In the composition of the present invention, in addition to the glycerin ester compound, conventionally known substances, that is, a lubricant, a slip agent, an antiblocking agent, a stabilizer, an antistatic agent, an antifogging agent, etc. Also, pigments and the like may be appropriately blended within a range that does not impair the performance of the intended film. Further, a small amount of other thermoplastic resin may be supplementarily added depending on the purpose within the range of not impairing the effects of the present invention. The method for preparing the composition of the present invention is not particularly limited and can be prepared by a known method. The composition ratio shown in the present invention means the state of the resin raw material immediately before being supplied to the extruder, or the component composition in the state of being a film,
Mixing timing of the glycerin ester compound, the order may be selected as conditions suitable for the process, it is not particularly limited, in a molten state after the completion of polycondensation, pellet state, or blended in the stage before film forming Is also good. Further, the composition of the present invention may be melt-kneaded by an extruder before film formation, processed into pellets, and then supplied to the film molding machine. The film of the present invention is formed by melt-kneading the above components by a usual T-die method, air cooling or water cooling inflation method.

[0008]

EFFECTS OF THE INVENTION The present invention provides a polyester resin material as a food packaging film which satisfies all the characteristics required for a food packaging film, such as self-adhesiveness, transparency and heat resistance in a microwave oven. . Polyvinylidene chloride film etc. have a problem of hydrogen chloride gas generation at the time of incineration disposal, but the polyester resin composition of the present invention does not generate a toxic gas at the time of incineration, and is environmentally friendly and practical as a new food packaging film. Above all, it is extremely effective.

[0009]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. Preparation of (A) Component Polyester Resin Preparation Example 1 1938.1 g of dimethyl terephthalate and 1348.8 g of 1,4-butanediol were charged together with 1.7 g of tetrabutyl titanate, which is an ester exchange catalyst, in a reactor equipped with a stirrer and a distillation tube. After sufficiently substituting with nitrogen, the temperature was raised to 140 ° C. under normal pressure and stirring was started. Further, the temperature was gradually raised and the by-product methanol was distilled off. When the temperature reached 210 ° C., the pressure inside the reactor was gradually reduced, and the temperature was kept constant at 250 ° C., and stirring was continued at a pressure of 0.1 torr for 2.5 hours to prepare a polyester resin A having an intrinsic viscosity of 1.03. The composition and melting point peak value are shown in Table 1.

Preparation Examples 2 to 7 Polyester resins B to G were prepared by changing the composition as shown in Table 1. The composition and melting point peak value are shown in Table 1.

[0011]

[Table 1]

Example 1 As the component (A), the polyester resin A 100 prepared above was used.
With respect to parts by weight, as the glycerin ester of component (B),
Blended with 1 part by weight of glycerin diacetomonolaurate,
20 liters of that was put into a Henschel mixer and pre-blended. Next, this blended product was supplied to a 40 mmφ twin-screw extruder, extruded in a strand form, and pelletized by a strand cutter. The pellets were preliminarily dried and formed into a film as described below, and various physical properties were evaluated. The results are shown in Table 2. [Preliminary drying and bleeding test]
Preliminary drying was performed at 5 ° C. for 8 hours with a blow dryer, and the bleeding property of the additive from the dried pellets was evaluated according to the following criteria. No bleed ◎ Almost no bleed ○ Slight bleed △ Very bleed × [Film molding] Pre-dried pellets are supplied to the hopper of the film molding machine (T die, 20 mmφ single screw extruder), and the film is drawn from the die. It was extruded into a shape and cooled by a cooling roll to form a film. Next, this film was cut into a 90 mm × 90 mm square and a biaxial stretching tester (manufactured by Toyo Seiki Co., Ltd.)
Was stretched to prepare a film having a thickness of 10 μm. The following evaluations were performed on this film. [Tensile Properties] Tensile strength and tensile elongation were measured and evaluated according to ASTM D882. [Tear strength] Measurement and evaluation were performed according to JIS P 8116. [Haze value] The haze value was measured and evaluated according to ASTM D 1003. [Self-adhesiveness] 3 cm ^{2 of two} test films with a width of 10 mm
The area was subjected to pressure bonding, and the shearing force required to separate the pressure bonding was measured by a tensile tester and evaluated according to the following evaluation criteria. 300 g or more ◎ 200 g or more and less than 300 g ○ 100 g or more and less than 200 g △ Less than 100 g × [microwave oven heat resistance] Seto dish (diameter 16 cm, depth 2.5
(50 cm) of olive oil was placed in (cm) and wrapped with a test film from above. The state of the film after being heated in a microwave oven for 3 minutes was evaluated for heat resistance in a microwave oven according to the following evaluation criteria. No change ◎ Almost no change ○ Some change △ Breaks, melts × cannot be lapped Examples 2 to 11, Comparative Examples 1 to 7 The same as Example 1 except that the composition was changed as shown in Table 2. Pellets were prepared, formed into a film, and various properties were evaluated. The results are shown in Table 2.

[0013]

[Table 2]

Claims (4)

[Claims] 1. One (1) hydroxyl group out of three hydroxyl groups of (B) glycerin per 100 parts by weight of (A) polyester resin has 4 carbon atoms.
A polyester resin composition for a food packaging film, which comprises 1 to 15 parts by weight of a glycerin ester compound in which at least one hydroxyl group is acetylated by being esterified with 30 to 30 aliphatic monocarboxylic acids. 2. The polyester resin (A), wherein the acid component constituting the polyester is mainly a terephthalic acid residue,
The polyester resin composition for a food packaging film according to claim 1, wherein the diol component is mainly a 1,4-butanediol residue and / or an ethylene glycol residue. 3. The melting point peak value of (A) polyester resin is 17
The polyester resin composition for a food packaging film according to claim 1 or 2, which has a temperature of 0 ° C or higher. 4. A food packaging film obtained by molding the polyester resin composition according to claim 1.