JPS6292826A - Heat-shrinkable polyester-based tube - Google Patents

Abstract

PURPOSE:To manufacture polyester tube, the joint of which does not deform by heating and the heat shrinkage of which is large, by a method wherein a film subjected to the specified stretching is formed into a tubular shape and, after that, its joint is bonded with a solvent of specified solubility index. CONSTITUTION:First, an unstretched film is manufactured by melt-extruding polyester-based polymer. Secondly, the resultant film is stretched so that the areal orientation coefficient becomes 100X10<-3> or less, the thermal shrinkage factor is 30% of more at 80 deg.C and 50% or more at 100 deg.C and the thermal shrinkage factor in long direction shows minimum value within the temperature range of 80+ or -25 deg.C after being stretched. Thirdly, the stretched film is formed into a tubular shape so as to manufacture a tubular body by applying a solvent of solubility index of 8.5-13.8 onto one surface of the formed film and overlapping the formed film immediately (before the solvent dries).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a tubular body made of a polyester film (including sheets, the same shall apply hereinafter), and specifically relates to containers, bottles (including plastic bottles). ) 9 Cans, stick-like objects (including pipes, sticks, wood, various stick-like objects), etc. (hereinafter abbreviated as containers), in particular, part or all of their caps, shoulders, bodies, etc. covering, marking, protecting,
Unity.

This invention relates to heat-resistant polyester tubes used for the purpose of improving commercial value.

[Prior Art] Conventionally, films made of polyvinyl chloride, polystyrene, polyethylene, hydrochloric acid rubber, etc. have been used for the above-mentioned purposes.
This was made into a tube-shaped body, which was then placed over the containers and heat-shrinked.

When manufacturing a tubular body using polyvinyl chloride or polystyrene, a solvent is often applied to the film for bonding, and ultrasonic sealing is sometimes used. In addition, when polyethylene is used as the material, a fusing seal method and an impulse seal method are also used. On the other hand, ultrasonic sealing has only just begun to be considered for polyester tubes.

[Problems to be Solved by the Invention] However, these conventional techniques have the following problems.

(a) Problems with industrial waste In recent years, the amount of plastic bottles used has increased rapidly. When considering the recovery of these bottles, there is a problem that they cannot be recovered and reused, especially if a different type of film such as vinyl chloride or polystyrene is used to cover a polyester bottle. Also, when incinerated, there are problems of high heat being emitted, which adversely affects processing equipment, and corrosion caused by chlorine gas.

(b) # Lack of heat resistance None of the conventional films described above can withstand high-temperature boiling or retort processing, making them unsuitable for sterilization. For example, when retort processing is performed, the conventional films are It will be destroyed and ruptured, and all functions will be lost.

On the other hand, polyester films, such as typical polyethylene terephthalate films, are expected to have heat resistance, but no tube has yet been developed that also exhibits excellent heat resistance at the bonded portion.

For example, if polyethylene terephthalate is ultrasonically sealed, a certain degree of bonding can be achieved. However, when boiling or retort processing is performed, the ultrasonic seal portion undergoes thermal deterioration and crystallization and becomes brittle, and when containers are packaged, the seal portion is damaged by impact.

(c) Printability Each of the above conventional films has its own drawbacks in terms of the generation of pinholes due to halftone printing and the adhesion with a wide variety of inks. For example, ink pinholes occur due to gel-like substances in polyvinyl chloride. If there are pinholes in the middle of a long film, if it is fed to an automatic labeling machine during continuous tube processing, the product will be manufactured with pinholes. Therefore, all products must be inspected at the end, and the actual operating rate is significantly reduced due to the labor involved and reprocessing by sampling. If this pinhole defect were to be inspected and removed after printing, it would be necessary to bond the film with adhesive tape to return it to a continuous film after cutting.

As a result, there is a seam, which results in a defective product due to the influence of the seam and the defective packaging must be removed during the process. Furthermore, in high-precision printing, the printing pitch decreases due to shrinkage of the film after printing (shrinkage over time), and moreover, it is difficult to manage because it constantly changes under the distribution temperature conditions. Therefore, for polyvinyl chloride shrink film, etc., refrigerated trucks, low-temperature warehouses, etc. are required.

(d) Generation of Crazes Polystyrene is prone to crazes, which is a problem in terms of product appearance, and also tends to cause crazes due to chemicals.

(e) Destruction of Labels on Containers The above-mentioned fusing seals and ultrasonic seals lack protection because the seals easily become a trigger for breakage due to the impact of dropping containers, etc.

(f) Whitening In the case of high-temperature bonding, the oriented film returns to an unoriented state and becomes whitened during post-processing, such as heat sterilization.

(g) Processing speed and bonding strength of joint parts Ultrasonic processing has already been put to practical use in tube processing of polyester polymers, and joining using adhesives is also being experimentally considered.

However, if you try to obtain sufficient sealing strength with ultrasonic sealing, you can only join at extremely low speeds, which lowers productivity and increases tube processing costs.Also, ultrasonic sealing is sensitive to the gap adjustment of the oscillator. This causes variations in the strength of the joint, and also deforms and damages the base material, causing embrittlement and failure.

On the other hand, adhesive bonding seems common sense at first glance, but unlike bonding by general lamination or coating, the film is folded before bonding, so there is the problem that the bonded parts tend to separate due to the repulsion effect based on the film's elasticity. be.

To prevent this, it is necessary to use an adhesive that instantaneously produces a high tack force, and in such a case, the application workability becomes low. Even if the bond were to be successfully joined, the adhesive would be heated and softened during the heat sterilization process in the core process, and the shrinkage stress of the film would cause scratches at the joint, resulting in a jagged joint and the adhesive protruding. This results in a state where only that part has an appearance different from the original film surface, which poses a problem in terms of commercial value.

The present invention has been made to overcome the drawbacks of the prior art as described above, and specifically, the joint portion exhibits heat shrinkage characteristics comparable to that of the film base material portion, and the joint portion The object of the present invention is to provide a polyester tube that can be joined without being deformed by heating.

[Means for Solving the Problems] The polyester tube of the present invention has a joint surface that is soluble or swellable and has a solubility index of 8.0 to 13.
8, the heat shrinkage rate in the circumferential direction is 30% or more at 80°C, 50% or more at 100°C, and the heat shrinkage rate in the longitudinal direction is It shows the minimum value in the temperature range of 80 ± 25°C [Function] With the appearance of plastic bottles, the problem of industrial waste has been widely discussed, and retrievability has been studied due to the need to avoid this problem. In addition, as importance has been placed on avoiding chlorine gas and smoke damage during incineration, polyester tubes are attracting attention.

In addition, tubes are being considered that can meet the demands for packaging automation, speeding up, and extending product life, such as tubes that are rigid enough to withstand high-speed operation and that can withstand heat sterilization. In particular, no heat-shrinkable tube that meets the above requirements has yet been completed.

Furthermore, in recent years, there has been a strong trend toward high-quality printing due to the visibility of printing effects 9 display, PR effects, etc., and the general trend is that films with dimensional stability are required. The same is true for heat-shrinkable tubes, which need to have heat-shrinkable properties while also exhibiting dimensional stability during the natural flow process.

Polyester tubes have been developed to meet these demands, but unfortunately various problems have been encountered in the process of forming the tubes. Although it is possible to manufacture polyester tubes using polyester film as the raw material and applying conventional ultrasonic sealing methods or adhesive bonding methods, as mentioned above, the processing speed is slow and The variation is large, and not only does the joint become a trigger for fracture, but also the joint and the base material do not exhibit the same shrinkage properties during heat shrinkage, resulting in shrinkage spots and wrinkles after shrinkage, so it is difficult to use as a heat shrink tube. This is a practical problem. When this plasticized tube is heat-shrinked and coated and then heat-sterilized, the joints often peel off or become misaligned due to softening, which poses a problem in terms of product appearance. Therefore, all the above-mentioned problems were solved by providing an integrated tube by using a solvent or a swelling agent on the premise that no adhesive was used other than the base film.

As a means to obtain the above properties, it is recommended to select a copolymer or a mixture thereof containing 30 to 90 mol% of aromatic dicarboxylic acid residues. An example of such a polyester is one or more dibasic acids selected from terephthalic acid, isophthalic acid, adipic acid, orthophthalic acid, sebacic acid, naphthalene dicarboxylic acid, etc. and ethylene glycol, butanediol, neopentyl glycol, cyclohexane dimethanol. Examples include polyester polymers produced using one or more diols selected from diols such as Chlor or 2-methoxyphenoxy)ethane4.
Non-limiting examples include 4'-dicarboxylic acid osylate.

A polyester/polyether block copolymer may be mixed with these polyesters to the extent that transparency is not impaired. The preferable intrinsic viscosity as a film base material is from 0.50 to 1.3 di/g, and as long as these polymers satisfy such an intrinsic viscosity value,
A polymer having a lower degree of polymerization or a higher degree of polymerization may be mixed within a range that accounts for % by weight or more.

The solvent or swelling agent used in the present invention has a solubility index of 8.
It is necessary to be within the range of 0 to 13.8. If the solubility index is less than 8.5, adhesion itself will not be achieved, and if it exceeds 13.8, the morphology of the film base material will be disturbed and good adhesion will not be obtained. At least one of these solvents or swelling agents should be used.

The effects of adopting the tube of the present invention can be clarified by comparing them with the above problems and can be summarized as follows.

(a) Regarding the problem of industrial waste, collection work will be made easier by using tubes similar to the polyester bottles that do not generate chlorine gas and are rapidly becoming popular these days. The present invention solved this problem by using a polyester film.

(b) The problem of insufficient heat resistance was solved by utilizing the excellent heat resistance of polyester films, and we succeeded in providing a tube that can be subjected to high-temperature hydrothermal treatment such as retort treatment. In particular, the joint surface must be able to withstand the high temperature hot water treatment.
Since they were bonded without using an adhesive, the high temperature resistance of the joint was no worse than that of the base material.

In other words, the main point of the tube of the present invention is that the base material and the adhesive part exhibit similar properties in terms of thermal shrinkage behavior, fracture resistance, heat resistance, etc., and these effects can be achieved without using an adhesive. This can only be achieved by adhering the substrate itself.

(C) Regarding printability, it is necessary to prevent the formation of gel that causes pinholes, so we used a polyester polymer with excellent thermal stability and stopped using many additives. . Therefore, excellent surface smoothness was obtained.

The properties required for tubes cannot be adjusted by using various additives, but by changing the acid and alcohol components that make up the polyester polymer and changing the molecular structure. Solved the problem of sexuality. In order to prevent problems such as shrinkage of the printing pitch over time after printing, it is particularly recommended to use a polyester polymer having a glass transition temperature of 35° C. or higher. More preferably, polymers having a glass transition temperature of 45°C or higher are more useful.

If the glass transition temperature is less than 35° C., the printing pitch changes during the natural distribution process, resulting in problems in terms of quality control, such as the need for transportation in refrigerated vehicles or storage in low-temperature warehouses.

Therefore, the polyester film of the present invention is a film formed from a polyester having a glass transition temperature of 35°C or higher, a copolyester polymer, and a mixture of this polymer and at least one other polymer. Useful. That is, polyethylene terephthalate homopolymer has some problems as a heat-shrinkable tube, and considering industrial production, polyester and polyester copolymer having a glass transition temperature lower than the glass transition temperature of polyethylene terephthalate by about 1°C or more are needed. It is necessary to use coalescence and mixtures thereof.

(d) Regarding the generation of crazes, the above-mentioned polyester polymer originally has the property of not generating crazes.

(e) With regard to the phenomenon of destruction due to dropping of containers or impact force during transportation, consideration was given to prevent destruction from occurring at the joints of the tubular bodies and to avoid causing essential damage to the film. This was achieved by bonding using a solvent instead of an adhesive, resulting in a tube with no thermal or mechanical damage and with strong bonding strength.

In producing these tubes by film end joining, solvents or swelling agents having a solubility index in the range of 8.0 to 13.8, such as benzene, toluene,
Aromatic hydrocarbons such as xylene and trimethylbenzene; methylene chloride, chloroform, ethylene dichloride, 1,1.
1-) Lichloroethane.

1. Aliphatic hydrocarbons such as 1.1.2-trichloroethane, 1,1,2.2-tetrachloroethane, trichloroethylene; halogenated aromatic hydrocarbons such as ortho-dichlorobenzene; phenol, metacresol, etc. Phenols; alcohols such as benzyl alcohol; nitride compounds such as nitrohydrocarbons such as nitrobenzene, nitriles such as acetonitrile, amines such as n-butylamine, pyridine, and morpholine; acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl cyclohexane, etc. Ketones; glycol ethers such as dioxane, ethers such as furans such as tetrahydrofuran; esters such as ethyl acetate, n-butyl acetate, monoethyl acetate; organic acids such as formic acid, acetic acid, fluoroacetic acid; sulfuric acid,
Inorganic acids such as nitric acid; sulfur derivatives such as carbon disulfide; N,
N-dimethylformamide and the like are used, and those with high volatility are particularly preferred.

The above is given as an example only, and of course is not limited thereto. In addition, the solvent or swelling agent may be used alone or in combination, and the joint portion of tubes joined using these solvents or swelling agents (hereinafter referred to as solvent) has a width of 50 m from the narrowest possible joint width.
The width may be as wide as m or more, of course, depending on the size of the container, but the standard width for ordinary bottles is 1 to 5 mm.

Also, the joint part may be joined in a single line, but two
It may be a film in which a plurality of linear joints are formed over a length of 100 cm or more, and since these joints cause almost no damage to the film base material, the properties of the polyester polymer are maintained. Not only does it have protective properties such as impact resistance and bottle breakage resistance, but it also does not suffer from a decrease in the degree of orientation due to heat shrinkage, nor does it exhibit any whitening or embrittlement phenomena due to subsequent heat treatment. This means that it satisfies the important basic required characteristics for heat-shrinkable tubes.

(f) The tube of the present invention has a heat shrinkage rate of 8 in the circumferential direction.
30% or more at 0°C, 50% or more at 100°C, more preferably 40% or more at 80°C, 100°C
It has high heat shrinkability of 55% or more. On the other hand, the thermal shrinkage rate in the longitudinal direction of the tube shows a minimum value at 80±25°C. Furthermore, the heat shrinkage rate of the heat shrinkable tube of the present invention at the seam is almost the same as that of the base film, and specifically, when the heat shrinkage rate performance of the base material is expressed as 100%, it is 80% or more, preferably 90%. Indicates a value of % or more. Incidentally, when the present inventors performed "bonding using a thermosetting type dry laminating adhesive," which is a common means of improving heat resistance, the heat shrinkage rate of the seam decreased due to the effect of the cured layer. have found that heat shrinkage wrinkles occur because the film exhibits heat shrinkage characteristics different from those of the base film. In order to prevent such heat shrinkage wrinkles from occurring, the heat shrinkage rate of the joint should be 80% of that of the base film.
It is desirable that it be above 80%, and when the tube is placed over the constriction of a bottle or the like, heat shrinkage wrinkles will occur particularly in areas where the constriction is large.

If the heat shrinkage rate of the tube of the present invention in the circumferential direction is less than 30% at 80°C, it will not be able to handle continuums with different diameters, and can only be used for items with little change such as straight pipes or cylinders. Also, the condition that the heat shrinkage rate in the circumferential direction at 100° C. is 50% or more is an extremely significant condition in terms of operation and effect, as described below. i.e. 80°C and 1
Since the difference in heat shrinkage rate in the circumferential direction at 00°C is configured as shown above, after the predetermined shrinkage occurs at a lower temperature of 80°C or less, the portion that requires a larger shrinkage will be It will contract with a delay as the value increases. This allows air to be removed step by step and smoothly, resulting in beautiful packaging. If the heat shrinkage rate of Zoo''C is less than 50%, it will not be possible to provide stable and beautiful packaging to all shapes of objects.

On the other hand, the fact that the thermal shrinkage rate in the longitudinal direction of the tube shows a minimum value in the temperature range of 80±25° C. has the following significance. In other words, shrinkage of the film occurs during the process of increasing the temperature of the film, but large shrinkage in the circumferential direction is observed in the above temperature range, so in terms of shrinkage in the length direction of the tube, it is within this temperature range. By suppressing the amount of shrinkage to a minimum value somewhere, dimensional errors in the length direction in the finished state are reduced, which is extremely important for making the package appearance beautiful. Generally, the heat shrinkage rate in the length direction should not exceed 15%, but in practice, the dimensional difference in the length direction of the tube is about 1° before and after heat shrinkage in the case of bottles.
The permissible size is ~7mm, and 1~3mm for small bottles.
It is hoped that it will be a struggle. Judging from these points,
For applications that require high precision, the heat shrinkage rate in the length direction is 100%.
Hereinafter, it is recommended that the content be more preferably 7% or less.

Further, it is desired that the tube of the present invention has a planar orientation coefficient of 100×10 −3 or less. In other words, the research conducted by the present inventors has revealed that unless the plane orientation coefficient is 100 x 10-3 or less, the adhesion by the solvent or swelling agent decreases, making instant bonding impossible. .

The tube of the present invention is one in which films are joined together using the above-mentioned solvent or swelling agent, but there are no particular restrictions on the method of forming the joint; (1) a method of simply overlapping; (2)
A method in which a tape-like material is provided on at least one side of the edge of the film to be bonded to the two, and (3) the film is bonded in a gassho-attached state, and the seal formed by this is bent to form a tube-like material on either side. Non-limiting examples include methods of joining to the body surface.

Next, examples will be described, and the measurement method was as follows.

1. Heat shrinkage rate Measured based on JIS standards 2. Bottle breakage test Using a 300 ml single service bottle, the length of the tube was determined so that the tube would extend up to the shoulder, and the bottle was covered with the heat shrink tube. After shrink-wrapping, fill the bottle with water and
The test was conducted in accordance with the JIS standard by dropping from a height of 1 cm.

3. Tube circumferential orientation coefficient and average plane orientation coefficient JI
The refractive index in three directions was measured using an S standard Abbe refractometer and calculated using the following formula.

Tube circumferential direction orientation coefficient: Ny-Nx Note that Nx: Tube longitudinal direction orientation coefficient Ny: Tube circumferential direction orientation coefficient Nz: Orientation coefficient in the thickness direction of the tubular film [Example] Example 1 Polyethylene (Tele/ A polyester-based polymer of iso)phthalate copolymer (tele/iso ratio = 80/20) was polymerized to an intrinsic viscosity of 0.75 dm/g, and 0.05% (by weight) of silicon dioxide was mixed. melt extruded,
An unstretched film was produced.

The film was stretched 4.2 times mainly in the transverse direction, and the film was stretched by a factor of about 12
% elongation, the transverse orientation coefficient is 101 x 10-
3. The heat shrinkage rate in the circumferential direction at a plane orientation coefficient of 24X10-3.80°C is 50%.

Heat shrinkage rate in ioo'a is 70%, thickness is 40pm
A heat-shrinkable polyvarnish film was produced. The film was printed to a width of 720 mm, and after printing, it was shredded to a width of 230 mm. The shredded film was applied to a tubular forming device, and dichloroethylene (sp value 9.87
) was applied, and the films were immediately overlapped (before drying) to produce a tubular body. Machining speed is 100+
/ It was a win. The results of the evaluation are shown in Figure 1.

Comparative Example 1 On the other hand, in order to compare with the film of the present invention, the copolymer of the present invention was stretched 1.8 times in the machine direction and 4.4 times in the transverse direction.
After stretching, heat treatment is performed at 150°C, and the transverse orientation coefficient is 96X1.
0-3, a plane orientation coefficient of 106 x 10-3, a heat shrinkage rate in the circumferential direction of 25% at 80°C and 32% at 100'C, and a thickness of 40 pm. Tube molding was performed in the same manner using this film.

Example 2 Each of the heat-shrinkable films obtained in Example 1 was evaluated for its practicality. As a result, the heat shrinkage rate at 80"O is more than 30% in the circumferential direction and 50% at 100°C.
or more, and the heat shrinkage rate in the length direction is 80±25°C
The tube that shows the minimum value of is found to be useful.

However, the solvent used in this example is methylene chloride and dioxane.
:1 mixture.

Comparative Example 2 Table 1 shows an example in which the conditions shown in Example 2 were changed so that the conditions were outside the scope of the present invention.

Example 3 and Comparative Example 3 The planar orientation coefficient was variously changed in Example 1, and the performance of the tube was evaluated and shown in Table 2.

Example 4 Using poly(ethylene terephthalate/cyclohexane dimethyl terephthalate) copolymer (70/30), 8
Thermal shrinkage rate at 0°C is 38% in the circumferential direction, 100°C
A tube was obtained which exhibited a minimum longitudinal heat shrinkage of -0.2% at 88°C. The circumferential orientation coefficient of the tube is 109X-3, and the planar orientation coefficient is 6.
9×10 −3 and bonded using dioxolane (Csp value 10.5). This tube showed excellent properties as shown in Table 3.

Comparative Example 4 A tube obtained from the film of Example 1 by ultrasonic sealing, which was statically firmly joined.

Comparative examples 5 and 6 The same film as in Example 1 was used, and the following solvent was used.

Comparative example 5 Rainbow brominated ethylene (SP value 7.84) Comparative example 6
: Isoprobyl ether (sp value 7.3) Comparative examples 4 and 5
．． The evaluation of 6 is shown in Table 3.

In this way, tubes with extremely excellent joints were obtained when the plane orientation coefficient was 100 x 10 -3 or less, but it was also found that when the plane orientation coefficient exceeded this, it was impossible to join. This joint can withstand boiling or retorting. Since no adhesive is used, it is possible to prevent the joint from becoming thicker as much as possible. Therefore, when a tubular body is continuously wound around a paper tube or a skein frame, it is unlikely that only the joints will be tightly wound or that the flatness of the folded tube will be damaged, allowing for good winding. .

[Effects of the Invention] Since the polyester tube of the present invention is constructed as described above, it is possible to obtain a beautiful and strong packaging state for covering packaging of bottles, and the tube has excellent printing stability and heat resistance. In addition, the processing speed and bonding strength of the bonded portion between the films were good, the productivity was good, and the morphological stability of the tube shape was also excellent.

Claims (5)

[Claims] (1) In a tubular body obtained from a heat-shrinkable polyester film, the joint surface thereof is soluble or swellable and at least one solvent having a solubility index of 8.0 to 13.8 or Bonded with a swelling agent, heat shrinkage rate in the circumferential direction is 30% or more at 80°C, 100°C
The heat shrinkage rate in the length direction is 80% or more.
A heat-shrinkable polyester tube characterized by exhibiting a minimum value in a temperature range of ±25°C. (2) Polyester film has a glass transition temperature of 35
℃ or higher, a film made of one or more materials selected from the group consisting of polyester, copolyester polymer, and mixture of the above polymer and at least one other polymer, Planar orientation coefficient is 100×
10. The heat-shrinkable polyester tube according to claim 1, which has a thickness of 10^-^3 or less. (3) Formed from a mixed or copolyester film containing 30 to 90 mol% of aromatic dicarboxylic acid residues, with a plane orientation coefficient of 100 x 10^-^3 or less, and a heat shrinkage rate of 30 in the circumferential direction. % or more, and a heat shrinkage rate of 15% or less in the longitudinal direction. (4) The form of the joint between the tubes is that they are simply overlapped, or that there is a tape-like material on at least one side of the butted films that joins the two;
Alternatively, the fin-shaped seal part is bonded in a gassho-attached state, and the resulting fin-shaped seal part is bent and joined to either one of the tubular body surfaces.Claim 1 The heat-shrinkable polyester tube according to any one of items 1 to 3. (5) Aromatic hydrocarbons with a solubility index of 8.5 to 13.8; halogenated hydrocarbons; halogenated aromatic hydrocarbons; phenols; alcohols; nitridation of nitrohydrocarbons, nitriles, amines, etc. Compounds; Ketones; Ethers such as glycol ethers and furans; Esters;
Any of claims 1 to 4, which is bonded with at least one dissolving or swelling liquid selected from the group consisting of organic acids; inorganic acids; sulfur derivatives; N,N-dimethylformamide. A heat-shrinkable polyester tube described in .