JPS61222738A - Film coated glass vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a glass container coated with a specific transparent heat-shrinkable film.

[Conventional technology]

Conventionally, the average molecular weight is 4, which is composed of 60 to 95% by weight of styrenic hydrocarbon and 5 to 40% by weight of conjugated diene hydrocarbon.
0 to 300,000 polystyrene to 100 parts by weight of resinous block copolymer (hereinafter referred to as thermoplastic resin)
A transparent film obtained by stretching a resin composition containing 30 parts by weight in a uniaxial, uniaxial, biaxial, or multiaxial direction at a stretching ratio of 2 to 8 times by a known tenter method or tubular method is , as seen in JP-A-48-13973, is a film that has excellent heat shrinkability, heat sealability, and gas permeability, as well as transparency and high gloss gold, making it suitable for packaging materials such as heat shrink packaging. ing.

However, in heat-shrink packaging, the stretched film made of this resin composition is susceptible to heat shrinkage stress, residual stress due to the shape of the packaged object, and storage stress of the packaged object after heat shrinkage to the packaged object (leak containers, etc.). In response to changes in the environment, thin cracks and cracks often occur in films (stress cracking phenomenon). These cracks and cracks not only impair the beauty and fragility of the shrink label, but also cause a loss of the protective effect on the packaged object, leading to a lack of suitability as a packaging material.

Generally, measures to prevent cracks include increasing the molecular weight of styrenic hydrocarbons or increasing the content of conjugated diene hydrocarbons in the block structure of the resin composition.

[Problem that the invention seeks to solve]

However, increasing the molecular weight reduces the flow of the resin, and increasing the content of conjugated dienes decreases the l1lt-
At the same time, it also lowers the starting temperature of heat loss, making it less suitable as a heat shrink packaging material. Therefore, simply adjusting the composition of the resin composition cannot prevent the occurrence of cracks and cracks under severe packaging conditions as described above.

An object of the present invention is to provide a film-covered glass container that is free from cracks and cracks on the surface of the covering film after heat-shrink packaging.

[Means for solving problems]

To summarize the present invention, the present invention relates to a glass container coated with a film, and comprises an average molecular weight of 40,000 to 40,000, consisting of 60 to 95% by weight of a styrene hydrocarbon and 5 to 40% by weight of a conjugated diene hydrocarbon.
100 parts by weight of a resinous block copolymer of 300,000 yen, 1 part of 10 to 30 g of polymethyleff, and (C) a rubber consisting of 20 to 50 wt% of a styrene hydrocarbon and 50 to 80 wt% of a conjugated diene hydrocarbon. 3 to 10 parts by weight of a block copolymer cL resin composition '1i- is characterized in that it is uniaxially, biaxially or multiaxially stretched, and then a glass container is heat-shrinkable covered with a transparent heat-shrinkable film.

The styrenic hydrocarbon that largely constitutes the block copolymer of the thermoplastic resin used in the present invention is styrene or α-methylstyrene, and the conjugated diene hydrocarbon is butadiene, isoprene, or the like. In order to produce a block copolymer from these monomers, there is a method in which the inner hydrocarbon monomer is polymerized stepwise using an anionic polymerization initiator, especially an organolithium compound. It is produced by a method of copolymerizing a mixture in an inert bath medium, or a method of appropriately using a combination of these methods. The proportion of styrenic hydrocarbon in the block copolymer is 60 to 9.
It is 5-fold iI'chi. If it is less than 60%, the resulting 'fC resin will resemble a rubber-like elastic body, making it unsuitable as a film, and if it exceeds 95%, the film having the above-mentioned properties, which is the object of the present invention, will not be suitable. I can't get it. The average molecular weight of the block copolymer is 40,000 to 300,000. IL<f
It is in the range of 160,000 to 250,000. If it is less than 40,000, the mechanical strength will decrease, and if it exceeds 300,000, the moldability will be poor and it will be difficult to form a film by stretching.The block copolymer has a general structural formula (A -B)n or (A-B
) n-A (A is a block W of a styrene hydrocarbon polymer, a block k of a BU conjugated diene hydrocarbon polymer
, n is a positive integer) and the general structural formula: % formula %) However, A is a styrenic hydrocarbon polymer block, B is a conjugated diene type a hydrocarbon polymer block, X is a residue derived from a polyfunctional compound, m is an integer of 1 or more, and n is 3 or 4.

It is made of a star-shaped block copolymer represented by As for the structure of the block, even if it is a complete block,
As seen in Publication No. 6, a so-called tapered block structure of AB random copolymer gold-containing copolymer is used in the transition region between block A and block B. These block copolymers can be classified structurally as follows.

+IIA-B 121 A-B-A (31A-B-A-B +41 A-B-A-B-A (51A-B-A-B-A-B (8) A-B-A-B- A-B-A (7) (
(A-B +3X (However, m and X are as above) (8) ((A-B) m37X (However, m and xh
V) The block copolymer having the structure (1) cannot be formed into a film due to its low tensile strength at high temperatures. structure(
2) The block copolymer with s(7L(3)) lacks stretch g film processability and also lacks heat shrinkability.On the other hand, the so-called multi-block copolymer with structure +3L(41, (5), (6)) The block copolymer has good stretching film formability and excellent heat shrinkability. That is, - film structural formula (A-B) n-A where n is 2 or more and needle 1 or Those with a rating of 3 to 5 are good.

Next, the polystyrene may be general transparent polystyrene with a molecular weight of 100,000 or more that can be molded using a molding machine. The polystyrene addition 11' is 10 to 30 parts by weight. The purpose of adding polystyrene is to improve the stiffness, transparency, and gloss of the film, but if the added amount exceeds 30 TL, the influence of polystyrene will be strong, resulting in a decrease in impact strength and an increase in stretching temperature. etc., which may impair the film's suitability as a packaging material and processability.

The rubbery block copolymer (hereinafter referred to as thermoplastic rubber) used in the present invention is a styrene hydrocarbon t-20 to 5
It is a block copolymer consisting of 50 to 80% by weight of oxts and conjugated diene hydrocarbon. This block copolymer has a conjugated diene hydrocarbon content of 50 to 8ON11.
% and high 9th, chemical 7! It is solid, exhibits rubber elasticity, and can be remelted without a crosslinking agent. If the conjugated diene hydrocarbon content is less than 501i1%, it exhibits resinous properties and oil resistance is reduced, making it undesirable.If it exceeds 80%, the transparency and stiffness of the film will decrease.

The resin composition used in the transparent heat-shrinkable film used in the present invention consists of 100 parts by weight of a thermoplastic resin, 10 to 30 parts by weight of polystyrene, and 3 to 10 parts by weight of a thermoplastic comb (L3 to 10 parts by weight). Thermoplastic rubber is added in an amount of α3 to 10 parts by weight per 100 parts by weight; if it is less than 13 parts by weight, the oil resistance will be poor and the effect of inhibiting cracking on the film after heat shrinkage will be small, and if it exceeds 10 parts by weight, 10 to 50 parts by weight of polystyrene is added to the glass container.More than 10 parts by weight of polystyrene is added. When added, the transparency is improved, but if it exceeds 30 parts by weight, the oil resistance, that is, the effect of inhibiting the generation of cracks in the heat-shrinkable film decreases, and the impact strength decreases and the stretching temperature increases, which is not preferable.

Furthermore, a lubricant, an antioxidant, an ultraviolet absorber, a coloring agent, etc. can be added to the resin composition as necessary. The resin composition used in the present invention may be mixed by tri-blending using a conventional Henschel mixer, ribbon blender, super mixer, V) blender, etc., or may be melted and pelletized using an extruder. Preferably, melt mixing is used.

Next, the stretching method used in the present invention may be either the tenter method or the tubular method.

The edge-setting of the glass container in the present invention may be carried out by a conventional method, for example, by forming a stretched film into a form that conforms to the shape of the glass container, covering the glass container, and blowing hot air onto it, or placing it in an oven. The film may be heat-shrinked by heating, etc., and brought into close contact with the glass container.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to examples.
The present invention is not limited to these examples.The method for measuring the physical properties of the film and the crack initiation accelerated test method that serves as an index of oil resistance and stress cracking resistance when applied to glass containers are as follows: , are as follows.

VICAT Softening Point JIS-6870 Heat Shrinkage Stress Heat shrinkage stress was measured under the following conditions using a heat shrinkage stress measuring machine manufactured by Toyo Koki Co., Ltd.

Sample shape (2) Thickness x 20 wm (width) x 100
Basket (long) Length direction is measured in low elongation direction iPA resistance: 14oc (heating medium: silicone oil)
The table values are stress (f)/thickness x width (Wa'') Tensile strength The strength against impact punching of the film was measured under JIS-6752 (vertical elongation direction) elongation conditions.

Impact spherical surface 1', 20°C haze ASTM-D-1005 heat shrinkage rate The film was placed in a constant temperature bath under the following conditions, and all heat shrinkage rates were measured.

Heat medium: silicone oil (in constant temperature bath) Time: 6Qsec Sample shape: 10X10crn After cooling, the film is heat-shrinked with Apply rapeseed oil evenly to the surface and The occurrence of cracks was observed. After application, long Time at which a crack of 5 m or more in length occurred This was taken as the total crack initiation time.

Example 1 Into a 100 t jacketed reaction vessel, fully dehydrated and purified benzene Aoz'6 was added, and a mixture of 9 parts styrene and 1 part butadiene was added, and the total activity of the difunctional butadiene oligomer dilithium initiator was added. α as terminal lithium
The LV polymerization is completed by adding 3 moles of the product and raising the temperature of the same product to 50°C. Next, a mixture of 8 parts of styrene and 2 parts of butadiene is further added and polymerized.

The obtained polymerization solution is subjected to steam stripping to recover the rainbow polymer. The number average molecule fi-f of this polymer is 1,175,000. (Styrene content 85%
, containing butadiene, [t15%] This polymer has the formula (A
-B) A block copolymer represented by n-A (n=3) was milled and the whole was pelletized.

For 100 M parts of this thermoplastic resin, polystyrene (Denka Styrol GP-1 manufactured by Denki Kagaku Kogyo Co., Ltd.)
10 parts by weight of i and 5 parts by weight of thermoplastic rubber [Toughgrain-A manufactured by Asahi Kasei Corporation] were added to form a bath-melt mixture into pellets.

This resin composition was press plate molded using a hot plate press machine at a molding temperature of 170° C. to obtain a sheet having a thickness of 225 μm 2×12 an. This sheet metal Toyo Seiki 2-shaft stretching was carried out with a single-shaft stretching.

Preheating temperature: 105C, preheating time: 90 seconds, stretching ratio: 4.5 times, stretching speed: 1. 12 x 54 at Brn/min
cm.

A film with a thickness of 48-52μ was obtained. Film characteristics, film forming conditions, etc. are shown in Table 1 below along with other examples.

Next, this film was placed on a glass container and heat-shrinked to produce a complete glass container covered with the film. The results of the transparency and cladding gold tests are also shown in Table 1.

Both haze and crack generation inhibition effects were good.

Example 2 5 parts by weight of polystyrene [Dencasterol GP-1 manufactured by Denki Kagaku Kogyo Co., Ltd.] il and thermoplastic rubber [Dencasterol GP-1 manufactured by Denki Kagaku Kogyo Co., Ltd.] were added to 100 parts by weight of a thermoplastic resin synthesized in the same manner as in Example 1. 8 parts by weight of Co. g-Tuffrene-A) were added and melted and mixed into pellets.

Using all of these pellets, film formation and crack initiation tests were carried out in the same manner as in Example 1. The results are shown in Cloth 1 along with the film-forming conditions and film-membrane physical properties. Both haze and crack generation prevention effects were good.

Example 3 50 parts by weight of polystyrene [Denka Styrol GP-1 manufactured by Denki Kagaku Kogyo Co., Ltd.] and thermoplastic rubber [Denka Styrol GP-1 manufactured by Denki Kagaku Kogyo Co., Ltd.] and 100 parts by weight of thermoplastic resin synthesized in the same manner as in Example 1 were added. 10 parts by weight of I was added and melted and mixed into pellets.

Using this pellet, in the same manner as in Example 1,
Film deposition and crack initiation tests were conducted. The results are shown in Table 1 together with the film-forming conditions and film-membrane physical properties. Both haze and crack generation inhibition effects were good.

Comparative Example 1 A film was formed and a crack initiation test was carried out in the same manner as in Example 1, using only the thermoplastic resin synthesized in the same manner as in Example 1. This result was calculated based on the film formation conditions and film-forming conditions.
Table 1 shows the properties of the film. Although the haze was good, the crack prevention effect was poor at 22 minutes.

Comparative Example 2 Polystyrene [Denka Styrol GP-13il manufactured by Denki Kagaku Kogyo Co., Ltd.] was added to 100 parts by weight of a thermoplastic resin synthesized in the same manner as in Example 1.

Parts by weight were added and melted and mixed to form pellets.

Using this Belen if stool piece, film formation and a crack initiation acceleration test were conducted in the same manner as in Example 1. The results are shown in Table 1 together with the film-forming conditions and film-membrane physical properties. Although the haze was good and rare, the crack generation prevention effect was very poor at 80 seconds.

Comparative Example 3 To 100 parts by weight of a thermoplastic resin synthesized in the same manner as in Example 1, 5 parts by weight of thermoplastic rubber [Toughprene A manufactured by Asahi Kasei Corporation]'ii was added, melted and mixed to form pellets.

Using this pellet, film formation and crack initiation tests were conducted in the same manner as in Example 1. The results are shown in Table 1 together with the film-forming conditions and film-membrane physical properties.

Although the effect of inhibiting crack generation is good, the haze is higher than in Example 1.

Comparative Example 4 Comparative example 4 was synthesized in the same manner as in Example 1, and 10 parts by weight of a thermoplastic rubber [manufactured by Asahi Kasei Corporation - Toughprene A: li] was added to 100 parts by weight of an exchange thermoplastic resin, and the mixture was melted and mixed into pellets.

Using this pellet, film formation and crack initiation tests were conducted in the same manner as in Example 1. The results are shown in Table 1 together with the film-forming conditions and film-membrane physical properties. The effect of inhibiting crack generation is good, but the haze is higher than in Example 3.

Comparative Example 5 To 100 parts by weight of a thermoplastic resin synthesized in the same manner as in Example 1, 15 parts by weight of thermoplastic rubber (manufactured by Asahi Kasei Corporation - Tuffrene-A) was added, and the mixture was melted and mixed into pellets.

This Belen)? A film was formed and a scissors generation acceleration test was conducted in the same manner as in Example 1. The results are shown in Table 1 along with the total film forming conditions and film properties.

Although the cracking prevention effect is good, the haze is high and the contents cannot be distinguished.

〔Effect of the invention〕

In addition to the above-described method, the film-coated glass container of the present invention is characterized by transparency, gloss, air permeability, and moisture permeability as well as heat-shrinkability and heat-sealability, which are the characteristics of the coated styrene thread resin film. It has excellent physical properties such as excellent oil resistance and stress cracking resistance, and has the remarkable effect of being beautiful and durable compared to conventional materials.

Claims (1)

[Scope of Claims] 1. (A) 100% by weight of a resinous block copolymer having an average molecular weight of 40,000 to 300,000 and consisting of 60 to 95% by weight of a styrene hydrocarbon and 5 to 40% by weight of a conjugated diene hydrocarbon. (B) 10 to 50 parts by weight of polystyrene, and (C) 0.3 to 10 parts by weight of a rubbery block copolymer consisting of 20 to 50 parts by weight of a styrene hydrocarbon and 50 to 80 parts by weight of a conjugated diene hydrocarbon. 1. A film-coated glass container, characterized in that the glass container is heat-shrinkable and coated with a transparent heat-shrinkable film obtained by stretching parts by weight of a resin composition uniaxially, biaxially, or multiaxially.