JPH07112729B2 - Container - Google Patents

Description

The present invention relates to a container, and more particularly to a container formed by thermoforming a resin laminate having excellent heat resistance, chemical resistance, mechanical strength and gas barrier property.

[Problems to be Solved by Prior Art and Invention]

Conventionally, various resin laminates have been used as packaging films, sheets, electrical / electronic members, and the like. It is also known that a styrene-based polymer layer is used as a resin layer constituting these resin laminates. However, the styrene-based polymer used here has an atactic structure, and has a high heat resistance. The properties, solvent resistance, hot water resistance and rigidity were not always satisfactory.

Further, a multilayer structure having a gas barrier property using a styrene polymer having an atactic structure is also widely known (JP-A-54-46281, JP-A-60-107337 and JP-A-60-337337).
-26072 publication). However, these are all multilayer structures containing an ethylene-vinyl acetate copolymer (EVOH) layer,
Due to the problem of EVOH cracking, there was a problem with moldability during thermoforming, heat resistance when used as a container, and gas barrier properties after retort treatment.

The present inventors eliminate the drawbacks of the above conventional resin laminate,
We have conducted intensive research to develop a container made of a resin laminate having various physical properties.

[Means for Solving the Problems]

In the process, a styrene-based polymer with high syndiotacticity developed by the group of the present inventors (Japanese Patent Laid-Open No. 62-104818) was used as a raw material, and this specific resin was laminated and further heat-treated. It was found that the molded container has excellent physical properties.

The present invention has been completed based on such findings. That is, the present invention contains a styrene-based polymer layer having a syndioctatic structure and a weight average molecular weight of 100,000 or more and a polyvinylidene chloride layer, and the layer thickness ratio between the styrene-based polymer layer and the polyvinylidene chloride layer is 1 The present invention provides a container formed by thermoforming a resin laminate having a size of 30 to 30.

The styrene-based polymer layer in the resin laminate constituting the container of the present invention is composed of a styrene-based polymer having a syndioctatic structure as described above, and this syndiotactic structure has a stereochemical structure of It has a syndiotactic structure, that is, it has a three-dimensional structure in which phenyl groups and substituted phenyl groups, which are side chains with respect to the main chain formed from carbon-carbon bonds, are alternately located in opposite directions. Nuclear magnetic resonance method with body carbon ( ¹³ C
-NMR method). ^The tacticity measured by the ¹³ C-NMR method can be indicated by the abundance ratio of a plurality of continuous constitutional units, for example, diad in the case of 2, triad in the case of 3 and pentad in the case of 5. However, the styrenic polymer having a syndioctatic structure referred to in the present invention is usually a racemic diad of 75
%, Preferably 85% or more, or racemic pentad having 30% or more, preferably 50% or more syndiotactic polystyrene, poly (alkylstyrene), poly (halogenated styrene), poly (alkoxystyrene) , Poly (vinyl benzoate), hydrogenated polymers thereof and mixtures thereof, or copolymers containing them as a main component. As the poly (alkylstyrene), poly (methylstyrene), poly (ethylstyrene), poly (isopropylstyrene), poly (tertiarybutylstyrene), poly (phenylstyrene), poly (vinylnaphthalene), There are poly (vinylstyrene) and the like, and as poly (halogenated styrene), there are poly (chlorostyrene), poly (bromostyrene), poly (fluorostyrene) and the like. Further, as poly (halogenated alkylstyrene), poly (chloromethylstyrene), etc., as poly (alkoxystyrene), poly (methoxystyrene),
Examples include poly (ethoxystyrene). Furthermore, as the comonomer component of the copolymer containing these structural units,
In addition to the above-mentioned styrene polymer monomers, olefin monomers such as ethylene, propylene, butene, hexene and octene, diene monomers such as butadiene and isoprene, cyclic olefin monomers, cyclic diene monomers, methyl methacrylate, maleic anhydride, acrylonitrile and the like. The polar vinyl monomers of

Among these, particularly preferred styrene-based polymers include polystyrene, poly (alkylstyrene), poly (halogenated styrene), hydrogenated polystyrene and copolymers containing these structural units.

A styrene-based polymer having such a syndiotactic structure can be obtained, for example, by using a titanium compound and a condensation product of water and a trialkylaluminum as a catalyst in an inert hydrocarbon solvent or in the absence of a solvent to form a styrene-based monomer. It can be produced by polymerizing a polymer (monomer corresponding to the above styrene-based polymer) (JP-A-62-187708). Further, poly (halogenated alkylstyrene) can be obtained by the method described in JP-A-1-46912, and these hydrogenated polymers can be obtained by the method described in JP-A-1-178505.

This styrene polymer has a weight average molecular weight of 100,000 or more, preferably 300,000 or more. Here, if the weight average molecular weight is less than 100,000, sufficient mechanical strength and heat resistance may not be obtained in some cases. Further, the molecular weight distribution is not limited in width and width, and various kinds can be applied. Furthermore, generally used thermoplastic resins, rubbers, inorganic fillers, antioxidants, plasticizers, compatibilizers, colorants and the like can be added to the styrene polymer.

On the other hand, as the polyvinylidene chloride constituting the polyvinylidene chloride layer, not only a vinylidene chloride homopolymer but also a copolymer with another vinyl monomer can be used. Here, examples of the other vinyl monomer include vinyl chloride and acrylonitrile. The molecular weight of this polyvinylidene chloride is not particularly limited, but it is preferable to use one having a weight average molecular weight of 20,000 or more, preferably 30,000 or more. Where the weight average molecular weight is 20,000
If it is less than the above range, sufficient elongation and impact resistance may not be obtained. Further, the molecular weight distribution is not limited in width and width, and various kinds can be applied.

The resin laminate constituting the container of the present invention comprises a styrene-based polymer (SPS) layer having the syndiotactic structure and a polyvinylidene chloride (PVDC) layer, which has the SPS layer and The PVDC layer is not limited to the two layers, but may be laminated in various forms including these two layers, and an appropriate adhesive (AD) layer or a thermoplastic resin layer may be interposed. Here, the number of layers and the stacking order are not limited, and may be appropriately determined depending on the situation. As the structure of the resin laminate, for example, SPS layer / AD layer / PVDC layer / AD layer
/ SPS layer, thermoplastic resin layer / SPS layer / AD layer / PVDC layer / AD layer / SPS
Layer, SPS layer / thermoplastic resin layer / AD layer / PVDC layer / AD layer / SPS layer,
A laminated structure such as a thermoplastic resin layer / AD layer / PVDC layer / AD layer / SPS layer can be considered. In these laminated structures, when one laminated body has two or more SPS layers or PVDC layers, they may be the same or different. Further, the laminated position of the thermoplastic resin can be set arbitrarily. As the thermoplastic resin, for example, when odor shielding is desired, polyethylene terephthalate, polycarbonate, or the like may be appropriately laminated according to the contents.

Further, in the resin laminate constituting the container of the present invention, the thickness of the entire layer is not particularly limited, but generally 150 to 2000
The thickness ratio of each layer may be appropriately determined according to the purpose of use, but is usually selected in the range of SPS layer / PVDC layer = 1 to 30, preferably 1 to 20. When another thermoplastic resin is laminated, it may be formed with an optimum thickness according to its purpose.

By the way, various methods can be considered for producing the resin laminate constituting the container of the present invention depending on the form and application of the laminate, and ordinary methods may be appropriately combined depending on the situation. Specifically, the following methods can be mentioned. That is, SPS and PVDC are multi-layer coextruded from a molding machine having a multi-layer guy to prepare a multi-layer cast molding film or multi-layer inflation molding. At this time, in order to enhance the adhesive force between the layers, an adhesive layer having an affinity with each of the SPS layer and the PVDC layer is provided as a third component, or an adhesive material is provided on either or both of SPS and PVDC. It can also be blended in advance. When making a multi-layer cast film, the T-die temperature should be about 280-350 ° C, and the cooling roll temperature should be SPS.
It is preferable to quench the molten resin extruded at a temperature not higher than the glass transition temperature of, particularly 30 ° C. or lower, and set the take-up speed within the range of 3 m / sec or less. In particular, if the cooling roll temperature is set to 30 ° C or lower, an amorphous film is obtained,
If the take-up speed is 3 m / sec or less, a non-oriented original sheet (film) can be obtained.

In this way, or if necessary, a stretching treatment is then performed to obtain a desired resin laminate. When a stretched multilayer film is produced by stretching here, as the stretching method, a method such as uniaxial stretching, tubular biaxial stretching, sequential biaxial stretching or simultaneous biaxial stretching may be appropriately selected and used. The conditions for this stretching process vary depending on the situation and are not uniquely defined, but usually the temperature is 80 to 140.
C., and the stretching speed may be set to 100 m / min or less. Further, it is preferable that the stretched multilayer film is subjected to a heat treatment as a post-treatment because sufficient dimensional stability can be obtained. The heat treatment temperature at this time varies depending on the melting point and glass transition temperature of the film to be used, but usually it may be set to 150 to 270 ° C., and the treatment time is about 5 seconds to 20 minutes.

In addition, an SPS film (stretched or unstretched) and a PVDC film (stretched or unstretched) are separately prepared in advance, and the resin laminate used in the present invention is also prepared by laminating these films. can do. In this lamination, each film surface may be treated by corona treatment, ozone treatment, or the like, or an interlayer adhesive (for example, a dry lamination adhesive such as a curable urethane adhesive) may be used. it can. In addition, the press roll temperature at the time of lamination is about 50 to 100 ° C, and the processing speed is 50 to 150 ° C.
m / min is suitable.

Among these various production means, it is particularly preferable to perform multilayer coextrusion using a molding machine having the multilayer die described above, or lamination to form a multilayer.

The resin laminate thus obtained can be molded (thermoformed) into various shapes while being heated to obtain a container having excellent heat resistance, solvent resistance, hot water resistance, and rigidity.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Reference Example (Production of Styrene Polymer) Toluene 2 as a solvent, 5 mmol of tetraethoxytitanium as a catalyst component and 500 mmol of methylaluminoxane as an aluminum atom were added to a reaction vessel, and styrene 15 was added thereto at 50 ° C. The polymerization reaction was carried out for a time. After the reaction was completed, the product was washed with a hydrochloric acid-methanol mixed solution to decompose and remove the catalyst component. Then, it was dried to obtain 2.5 kg of a styrene polymer (polystyrene). Next, this polymer was subjected to Soxhlet extraction using methyl ethyl ketone as a solvent to obtain an extraction residue of 95% by weight. The weight average molecular weight of this product was 800,000. Also 1,2-
From analysis by ¹³ C-NMR measurement using dichlorobenzene as a solvent, absorption was observed at 143.35 ppm due to the syndiotactic structure, and the syndiotacticity in the racemic pentad calculated from the peak area was 96%. there were. The polystyrene thus obtained was added with bis (2,4-di-butylphenyl) pentaerythritol diphosphite and tetrakis [methylene (3,5-di-butyl-hydroxyhydrocinnamate)] methane as antioxidants. Each of them is mixed by 0.1 part by weight, and the diameter is 40m.
It was extruded by a m twin-screw extruder and pelletized. The styrene polymer (SPS) thus obtained had a melting point of 270 ° C and a glass transition temperature of 100 ° C.

Example 1 Syndiotactic polystyrene (SPS) obtained in the above reference example and polyvinylidene chloride (weight average molecular weight of about 90,00
0) (PVDC) and an adhesive (urethane type) (AD) were used to prepare a multilayer sheet by a dry lamination method.

The combination of sheet layers is SPS / AD / PVDC / AD / SPS (thickness 0.
9 mm, PVDC thickness average 36 μm, PVDC thickness ratio 4%). This sheet is indirectly heated, opening area 37 cm ² , volume 95 ml
The container was molded and the thermoformability, heat resistance, and gas barrier property were observed. The results are shown in Table 1.

Comparative Example 1 As in Example 1, except that SPS was changed to polystyrene having an atactic structure (weight average molecular weight 30 × 10 ⁴ , trade name: Idemitsu Polystyrene HH30E, manufactured by Idemitsu Petrochemical Co., Ltd.) (aPS). A container was prepared in the same manner, and thermoformability, heat resistance, and gas barrier property were observed. The results are shown in Table 1.

Comparative Example 2 In Example 1, PVDC was used as an ethylene-vinyl acetate copolymer (trade name: Eval Film, manufactured by Kuraray Co., Ltd.) (EV
A container was prepared in the same manner as in Example 1 except that OH) was used, and thermoformability, heat resistance, and gas barrier property were observed. The results are shown in Table 1.

Comparative Example 3 Only SPS obtained in the above reference example was cast-molded at 30 ° C.
It is rapidly cooled with a cooling roll to create a 0.9 mm thick sheet,
Using this single layer sheet, a container was molded in the same manner as in Example 1, and thermoformability, heat resistance and gas barrier property were observed.
The results are shown in Table 1.

Comparative Example 4 Only aPS used in the above-mentioned example was cast-molded and rapidly cooled with a cooling roll at 30 ° C. to form a sheet having a thickness of 0.9 mm, and this single-layer sheet was used in the same manner as in Example 1 to form a container. Was molded, and thermoformability, heat resistance, and gas barrier properties were observed. The results are shown in Table 1.

[Advantages of the Invention] As described above, the container of the present invention has excellent gas barrier properties of PVDC while maintaining good heat resistance, acid resistance, alkali resistance, hot water resistance, rigidity and electrical characteristics of SPS, Breaking strength etc. are given.

Therefore, the container of the present invention, including for general packaging,
It is expected to be used effectively and widely for electric / electronic materials, food packaging that requires heat resistance and hot water resistance, and industrial material packaging.

Claims (1)

[Claims] 1. A styrene-based polymer layer having a syndiotactic structure and a weight average molecular weight of 100,000 or more and a polyvinylidene chloride layer, and the layer thickness ratio of the styrene-based polymer layer and the polyvinylidene chloride layer is 1 A container formed by thermoforming a resin laminate of ~ 30.