JPH04265B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a stretched polyvinyl chloride film for labels that allows shrink labeling of containers and the like at low temperatures. BACKGROUND ART Traditionally, heat-shrinkable labels made from polyvinyl chloride film (hereinafter referred to as "PVC film") that has been uniaxially stretched horizontally and made into cylindrical bags have been used for glass containers and containers made of various synthetic resins. In recent years, demand for stretched bolt containers made of polyethylene terephthalate (hereinafter referred to as "PET bottles") has been increasing in various fields due to their excellent characteristics such as lightness and transparency. However, ordinary products that have not been subjected to special treatments such as heat treatment
PET bottles have a serious drawback that when shrink labeling is performed using the above-mentioned PVC film, the bottles are thermally deformed. In order to solve the above drawbacks, there is a need for a PVC film for labels that has good shrink labeling properties at lower temperatures (hereinafter referred to as "low temperature shrink properties").
Furthermore, shrinkage of the film when left at room temperature,
Low natural shrinkage is a required property for a label film, but PVC films that generally have good low-temperature shrinkage also have large natural shrinkage, making it difficult to satisfy both properties. The present invention is based on the discovery of a combination of plasticizers that satisfies the above-mentioned required properties and also enables stable film production. ~60
2 to 9 parts by weight of powdered plasticizer and 4 parts by weight of liquid plasticizer at ℃
9 parts by weight of a plasticizer is added in a range of 10 to 15 parts by weight, and the film is uniaxially stretched. The polyvinyl chloride resin used in the present invention includes not only a vinyl chloride homopolymer but also a copolymer of vinyl chloride and a monomer copolymerizable with vinyl chloride such as vinyl acetate. In the present invention, it is necessary to mix specific amounts of a powder plasticizer and a liquid plasticizer with this polyvinyl chloride resin. The above powdered plasticizer has a melting temperature of 45~
60℃, specific examples include triethylene glycol dibenzoate (melting temperature, 47℃),
Examples include neopentyl glycol dibenzoate (melting temperature, 49°C), triphenyl phosphate (melting temperature, 49°C), and the like. The reason for using a powdered plasticizer with a melting temperature in the range of 45 to 60°C is that PET bottles usually begin to deform at around 65°C, so the label film used should have a melting temperature that is higher than the bottle's deformation temperature. It is necessary to have sufficient shrinkability at low temperatures. From this point of view, if a large amount of ordinary liquid plasticizer is used, the objective can be achieved, but conversely, the natural shrinkage at room temperature increases, making it impractical. Since the powdered plasticizer used in the present invention is solid at room temperature, it does not promote natural shrinkage, and it is assumed that it becomes liquid at the labeling temperature and enhances shrinkage similar to ordinary liquid plasticizers. Powdered plasticizers with a melting temperature of less than 45°C have a large natural shrinkage;
Anything exceeding this value has poor low-temperature shrinkability and is inconvenient. Next, the liquid plasticizer used in the present invention is DOP
Ordinary room-temperature liquid plasticizers such as DOA and DOA can be used, and are used for the purpose of solving problems in the production of the above-mentioned powdered plasticizers. In other words,
The film of the present invention is made by molding raw materials into a film shape by extrusion molding method, etc. However, raw materials using only the powdered plasticizer described above tend to solidify into lumps at around room temperature, making it difficult to transport the raw materials or send them to the extruder. Because supply is not carried out smoothly and the plasticizer itself has poor thermal stability, stable production cannot be maintained using an extruder or the like.
Therefore, if a specific amount of liquid plasticizer is used in combination, the above-mentioned trouble can be solved. Regarding the amount used, a total of 10 to 15 parts by weight of a plasticizer consisting of 2 to 9 parts by weight of the above powdered plasticizer and 4 to 9 parts by weight of liquid plasticizer is added to 100 parts by weight of polyvinyl chloride resin. . If the liquid plasticizer is less than 4 parts by weight, the above-mentioned manufacturing troubles cannot be solved, and if it exceeds 9 parts by weight, the natural shrinkage becomes large, which poses a practical problem. If the total amount of the plasticizer is less than 10 parts by weight, the shrinkage necessary for a label film cannot be obtained, and if it exceeds 15 parts by weight, the film becomes stiff and difficult to use. The film of the present invention is obtained by molding the above-mentioned composition into a film by extrusion molding or the like, and then stretching the film primarily in a uniaxial direction. The stretching conditions can be the same as before, and the stretching temperature is 80~
The stretching is carried out at 95° C. and at a stretching ratio of 2 to 3 times in the main direction.
Note that it may be stretched slightly (about 1.1 to 1.3 times) in a direction perpendicular to the main direction. Hereinafter, the present invention will be explained in detail with reference to Examples. Examples Common formulation PVC (=800) 100 parts by weight Stabilizer (Sn-based) 5 MBS resin 10 Lubricant 0.5 Each composition prepared by adding the plasticizer shown in Table 1 to the above common formulation was molded using an extrusion molding machine. After extrusion, the stretching temperature is 90
℃, uniaxially stretched at a transverse stretching ratio of 2.4 times to a thickness of 40μ
I got the film. Table 1 shows the evaluation of extrusion processability at this time. Next, each film was made into a cylindrical bag so that the direction of stretching was in the circumferential direction to create a label. Use this label on an empty PET bottle (diameter 76mmφ, internal volume 1)
), and by changing the heating temperature (hot air temperature) and time in a hot air shrink tunnel, we examined the appropriate range of use as a label and evaluated its low-temperature shrinkability. Furthermore, the results of measuring the natural shrinkage of the label are shown in Table 1. Regarding processability, when the prepared raw material composition is cooled to room temperature after blending, the raw materials coagulate and solidify, and transportation troubles do not occur at all (○), those that occur frequently (△), and those that always occur (×)
And so. Regarding low-temperature shrinkability, labels whose shrinkage temperature was considerably lower than the deformation temperature of PET bottles and were rated as (○) had no problem. Natural shrinkage is determined by leaving the film in an atmosphere at 30°C and having a shrinkage rate of 0.6% or less after 5 days (○), 0.6
Those exceeding % were marked (×).

[Table] From Table-1, films of the present invention, Nos. 3 to 5
It can be seen that the processability, low-temperature shrinkability, and natural shrinkage are all good. No. 2 with a small amount of DOP, a liquid plasticizer, and No. 1 with no additives have poor workability,
It can be seen that No. 6, which does not contain the powdered plasticizer TPP, has poor natural shrinkage.

Claims (1)

[Claims] 1 A total of 10 to 15 parts by weight of a plasticizer consisting of 2 to 9 parts by weight of a powdered plasticizer with a melting temperature of 45 to 60°C and 4 to 9 parts by weight of a liquid plasticizer to 100 parts by weight of polyvinyl chloride resin.
1. A low-temperature shrinkable film for labels, which is uniaxially stretched and contains within the range of parts by weight.