JP3090674B2 - Single layer packaging material for high temperature filling - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polybutylene terephthalate resin high-temperature packaging material that can be filled as it is without cooling a high-temperature fluid.

[Conventional technology and its problems]

Recently, plastics have been widely used in the packaging of foods and beverages, such as natural juice, milk, etc., after pasteurization at high temperature and after preparation at high temperature, such as chocolate, packed in containers and provided to the market. Higher temperature filling requires more properties than low temperature filling. That is, the strength of the container at the filling temperature is high, the container does not deform due to heat shrinkage, the container does not whiten due to heat crystallization, and the transfer or transmission of taste and aroma (smell) is small.

However, conventionally used containers of polyethylene, polyolefins such as polypropylene, ionomers, ethylene-vinyl acetate copolymer, etc. have poor heat resistance, and may be deformed when filled at high temperatures, especially at 100 ° C or higher, or Because of the high temperature, the problem of so-called taste and odor (polyodor) transfer becomes even more serious. Therefore, for example, in the case of milk, after high-temperature sterilization (130-135 ° C for several seconds), it is once cooled to about 60 ° C, and in the case of chocolate, it is 160
It is necessary to refill in a disposable container, cool it down, and refill it in another container, because it is filled at ~ 180 ° C.
Not only wasted time wasted, but the process was complicated and uneconomical.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve these problems, and as a result, polybutylene terephthalate resin has heat resistance,
It has excellent oil resistance, is tasteless and odorless, and since such properties are maintained even at high temperatures and has heat sealing properties, it has been found that it is extremely suitable as the high temperature filling packaging material. The inventors have found that the film has sufficient strength even with a single layer, and have completed the present invention.

That is, the present invention provides a high-temperature filling packaging material made of polybutylene terephthalate resin for filling a fluid having a filling temperature of 80 ° C. or higher.

Polybutylene terephthalate used in the present invention,
A polyester whose main repeating unit is butylene terephthalate, specifically, a polyester obtained by condensing 1,4-butanediol with terephthalic acid or a lower alcohol ester thereof, and a copolymer mainly comprising polybutylene terephthalate. It may be. It is preferably a homopolymer or a branched polymer in terms of heat resistance, gas barrier properties, and fragrance retention. Here, the copolymer is mainly terephthalic acid or its lower alcohol ester as a dibasic acid component, and the other dibasic acid component is 40 mol
A polyester composed of 1% or less, or a polyester composed mainly of 1,4-butanediol as a glycol component and 40 mol% or less of other glycol components. Further, polyesters whose main components are terephthalic acid or its lower alcohol ester and 1,4-butanediol, and the total of other dibasic acid components and other glycol components is 40 mol% or less are also included.

Here, as the dibasic acid component other than terephthalic acid or its lower alcohol ester, isophthalic acid, orthophthalic acid, adipic acid, sebacic acid, succinic acid, oxalic acid and the like and lower alcohol esters thereof can be used. As the glycol component other than 1,4-butanediol, ordinary alkylene glycols such as ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, hexamethylene glycol, neopentyl glycol, and cyclohexane dimethanol can be used.

Further, a branched polymer belonging to a copolymer can also be used. The term "PBT branched polymer" as used herein refers to a polyester mainly composed of a so-called polybutylene terephthalate or butylene terephthalate unit and branched by adding a polyfunctional compound. Examples of the polyfunctional compound that can be used here include trimesic acid, trimellitic acid, pyromellitic acid and their alcohol esters,
Examples include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. The addition amount of these polyfunctional compounds is 1 mol% or less as an acid component or a glycol component.

In the polybutylene terephthalate resin of the present invention, known substances added to general thermoplastic resins and thermosetting resins can be appropriately used according to required performance, as long as the effects of the present invention are not impaired. Further, a small amount of other thermoplastic resin or inorganic filler may be supplementarily used depending on the purpose within a range not to impair the effects of the present invention.

In the present invention, the packaging material is a general term for bags, containers, and the like, and the bags can be obtained by forming a polybutylene terephthalate resin into a film by an inflation method or a T-die method as described below, and then forming the film by heat sealing or the like. it can. In addition, the container is made by injection molding, film,
The sheet can be obtained by thermoforming such as vacuum forming.

The film made of the polybutylene terephthalate resin of the present invention is formed by using an inflation molding method or a T-die method using the polybutylene terephthalate resin. In particular, a film prepared by the inflation molding method is preferable because it has many advantages, such as high tensile strength and excellent gas barrier properties, as compared with a film obtained by the T-die method, and can be manufactured at low cost.

The inflation method is a method often used for forming polyethylene into a film, and is a method of forming a film into a tube. In the T-die method, an extruded film is formed from a linear slit extrusion molding die, and the productivity is overwhelmingly superior to the inflation method. However, the resin material is limited in the inflation method,
It could not be said to be applicable to any resin, and it was thought that it could not be applied to polybutylene terephthalate resin. However, if a specific polybutylene terephthalate resin, specifically one having an intrinsic viscosity of 1.0 or more, preferably a comparatively high viscosity of 1.0 to 2.5, is selected, it is clear that film can be formed by the inflation molding method. It has been found that it has better physical properties for the purpose of the present application than the plastics film described above.

However, when a polybutylene terephthalate resin having an intrinsic viscosity of less than 1.0 is used, molding is difficult regardless of the inflation conditions. Inherent viscosity of 1.0 from physical properties
When it is necessary to use a material smaller than the above, a film may be formed by a T-die method. Inherent viscosity of 0.5 even when using the T-die method
Above, preferably 0.7 or more.

In particular, the inflation molding method is preferable because a tubular film can be obtained, and a bag can be easily and inexpensively formed by cutting the film into a certain length and heat-sealing one end.

The fluid to be filled in the packaging material of the present invention means a material that exhibits fluidity at the filling temperature, and is a liquid such as the natural juice or milk, a curry roux that is solid at ordinary temperature, food such as chocolate, and further hot melt adhesion. And industrial products such as resin melts, waxes, paints and the like.

The packaging material made of the polybutylene terephthalate resin of the present invention has no odor peculiar to the resin and is tasteless, so that the odor and taste are not transferred to the food, and the odor component of the content is less adsorbed to the resin, It has the characteristic that this property is maintained even at high temperatures.

That is, natural juices, water-based foods and beverages such as milk are heat-sterilized at a temperature of about 80 to 100 ° C., and curry roux and oil-based foods and beverages such as chocolate are prepared at a high temperature.
Bags and containers are filled at a temperature of about 180 ° C. In the case of a conventional polyolefin container, the decomposition and dissolution of the resin under such high temperatures caused a drastic change in the taste and odor of foods and beverages. The packaging material for hot filling according to the invention has no such problems.

Furthermore, a film made of polybutylene terephthalate resin has heat sealability, is excellent in printability, and has mechanical strength as a food packaging bag, so that it can be used as a single layer and is suitable as a packaging material.

Films conventionally used as sealants have low mechanical strength in the heat-sealed portion, and may easily break or break at the sealed portion, and may break the bag. I needed to.

On the other hand, the polybutylene terephthalate resin has excellent mechanical strength in the heat-sealed portion, so that it is not cut at the heat-sealed portion, hardly breaks during transportation and handling, and the film itself is strong, so the thickness of the film is high. Is economical because it can be thinned.

For example, the strength of a blown film of polybutylene terephthalate resin is two to three times as high as that of a low-density polyethylene or polypropylene blown film, and is excellent in tear strength and impact strength.

Although there are films superior to polybutylene terephthalate resin films only from the viewpoint of heat resistance, they are not required for the other required performances of the present invention, for example, insufficiency in fragrance retention, and the resin itself is expensive. In some cases, or because inflation molding is not possible, the film form is more expensive. Further, in order to impart heat sealability to the bag making, it is used by laminating it with another film, so that the productivity is poor and there are problems such as peeling of the laminated portion. On the other hand, since the polybutylene terephthalate resin film used in the present invention can be obtained by inflation molding, since it has more excellent properties in a single layer,
An economical food packaging bag with higher productivity can be obtained.

The packaging material of the present invention can be used alone as it is as a bag or a container, and can also be suitably used, for example, as an interior bag of a metal or resin drum.

〔The invention's effect〕

As described above, the polybutylene terephthalate resin high-temperature filling packaging material of the present invention has excellent fragrance retention, has no peculiar odor like polyethylene resin or polypropylene resin, and is tasteless, and is particularly important as a food packaging material. Since a certain odor is not transferred to the food, the flavor of the food is not impaired, and such properties are maintained even at a high temperature, it is extremely excellent as a packaging material for filling foods and resin melts at a high temperature. In addition, the polybutylene terephthalate resin film used in the present invention can be obtained by inflation molding, and can be heat-sealed. Furthermore, since the single layer has excellent properties, an economical food packaging bag and industrial product packaging bag with higher productivity can be obtained.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples.
The present invention is not limited to these.

Examples 1 to 5 and Comparative Example 1 As shown in Table 1, a film having a thickness of 50 μm was prepared from various polymers by various production methods, and three sides were heat-sealed to produce a three-side seal bag having a width of 95 cm and a length of 180 cm. I bagged.

The polybutylene terephthalate resin bag prepared in this manner was used as an inner bag of a drum made of high-density polyethylene resin having a capacity of 200, and this was filled with 180 ° C orange juice (100% fruit juice reduced concentrate) at 180 ° C. The part was closed with a nylon tie wrap band, covered with a high-density polyethylene resin lid, and stored at room temperature. One week later, the container was opened and the amount of the odor component (d-limonene) in the orange juice, the amount of d-limonene adsorbed on the inner bag, and the amount of d-limonene adsorbed on the high-density polyethylene resin drum were determined. Was. In addition, a sensory test was performed to determine whether the taste and smell of orange juice had changed, and whether the smell of orange juice had adhered to the inner bag and the drum. The evaluation result was expressed by the number of panelists who judged that there was no change among the 10 panelists.

In addition, as a comparative example, Example 1 was repeated except that the interior bag was changed to a low-density polyethylene resin (LDPE) having a thickness of 80 μm.
The test was performed in the same manner as described above.

Among the sensory tests, the degree of change in taste and smell of orange juice was examined in comparison with orange juice filled in a glass container.

 The results are shown in Table 1.

The PBT homopolymer used in the examples is Duranex (trade name) manufactured by Polyplastics Co., Ltd. PBT branched polymer, PBT copolymer A, and PBT copolymer B are monomers described below as copolymer components, respectively. It is used in the ratio described below, and is produced by melt polycondensation of 1,4-butanediol and an acid component by a conventional method.

Examples 6 to 9 and Comparative Examples 2 to 4 As shown in Table 2, various kinds of fillers were filled into bags at various filling temperatures, and heat resistance (appearance change; (1) deformation or melting (2)
Change in hue). In addition, sensory tests were conducted by 10 panelists for changes in fragrance retention, taste of the filling, and odor.

In addition, about the change of the fragrance retention, the taste of the filling, and the smell, the degree of the change was examined in comparison with that in a Pyrex glass container. The evaluation results were expressed as the number of panelists who evaluated that there was no change among the 10 panelists. However, regarding the fragrance retention, after filling, the container is sealed with a heat seal, sealed in a glass container, and sealed at room temperature for 1 week. The evaluation was made on a three-point scale, that is, a substance with a slight smell) and an X (a substance with a strong smell).

 Table 2 shows the results.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B65D 1/00 C08G 63/00-63/91 C08L 67/04-67/04

Claims (7)

(57) [Claims] 1. A high-temperature filling single-layer packaging material made of a polybutylene terephthalate resin for filling a fluid having a filling temperature of 80 ° C. or higher. 2. The filling temperature is 100 ° C. or higher.
A single-layer packaging material for high-temperature filling according to the above. 3. The single-layer packing material for high-temperature filling according to claim 1, wherein the fluid to be filled is an aqueous food or beverage. 4. The high-temperature filling single-layer packaging material according to claim 2, wherein the fluid to be filled is an oil-based food or beverage. 5. The single-layer packaging material for high-temperature filling according to claim 1, wherein the fluid to be filled is one of a resin melt, wax and paint. 6. The packaging material according to claim 1, wherein the packaging material is a bag or a molded container.
The single-layer packaging material for high-temperature filling according to any one of claims 1 to 5. 7. The single-layer packing material for high-temperature filling according to claim 6, wherein the bag is an interior bag.