JPH09314658A - Uniaxially stretched aliphatic polyester film and method for producing the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a uniaxially stretched aliphatic polyester film formed by using a polycondensation aliphatic polyester excellent in transparency, mechanical strength and product dimensional stability, and a method for producing the same. [Structure] Mainly synthesized from 1,4-butanediol and succinic acid, temperature 190 ° C., shear rate 100
Melt viscosity at (sec ⁻¹ ) is 4,000 to 100,
An aliphatic polyester having a melting point of 80 to 120 ° C. and a number average molecular weight of 30,000 or more was molded by an extrusion film forming method. This is then placed at 35
A uniaxially stretched aliphatic polyester film having a haze of 2.0 to 10.0% and an impact strength of 2 kg · cm or more was obtained by stretching 3 to 8 times in the machine direction at a temperature lower by -50 ° C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shrink wrapping material and a transparent material, and more specifically, it is molded from an aliphatic polyester resin having a practically sufficient high molecular weight, and has transparency, mechanical strength and products. The present invention relates to a uniaxially stretched aliphatic polyester film having excellent dimensional stability and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a packaging material used for shrink wrapping, a film of polyvinyl chloride, polypropylene, polyethylene or the like is known, and in addition to heat shrinkability, heat sealability, impact resistance, etc. It has unique characteristics. However, since these films are non-biodegradable, they will exist semi-permanently in nature unless they are reused or incinerated, and today their difficulty in waste disposal is a problem. The incineration process not only costs a large amount of money, but also the high heat amount generated during incineration or the corrosive gas generated during incineration in the case of polyvinyl chloride may damage the incinerator.

As one of the solutions to the problem of waste treatment, molded products made of biodegradable resin have been attracting attention. As the biodegradable resin, for example, starch and ethylene vinyl alcohol Coalesce, composite of chitin and cellulose,
Aliphatic polyester produced by microbial fermentation, ε
-Aliphatic polyester chemically synthesized from caprolactone has been reported. However, these have drawbacks such as poor moldability, and are therefore limited in the range of use.

The inventors of the present invention were able to obtain an unprecedented high molecular weight aliphatic polyester having biodegradability mainly from glycols and an aliphatic dibasic acid or an acid anhydride thereof, which are practically sufficient. It has been proposed, for example, in Japanese Patent Laid-Open No. 189822/1992 that it has excellent physical properties and moldability. Further, the inventors of the present invention, by utilizing the characteristics of such a resin, can be used for a sheet or a film,
The obtained sheet or film can be decomposed by microorganisms, and even if it is discarded, the calorific value of combustion is small,
It is excellent in thermal stability and mechanical properties, has heat sealability, and has excellent transparency as a stretched product, and it has excellent properties as a packaging sheet or film. It was proposed by JP-A No. 6-170941, JP-A No. 7-47598 and the like.

Further, as a shrink wrapping material for a uniaxially stretched film, a heat shrinkable film having sufficient shrinkability was proposed in JP-A-7-292134. However, since the stretching temperature of these films is near the melting point of the resin, the impact strength is low, and the heat setting treatment after stretching is insufficient.
There is a problem that the product value may be lost due to shrinkage over time when stored in a warehouse or the like. A uniaxially stretched film has sufficient shrinkage in the stretched direction during shrink wrapping, but does not shrink in the direction perpendicular to the stretching direction, and on the contrary, the shrinkage rate is minus a few%, and Since it stretches, there is a problem that the edge portion in the lateral direction of the film is difficult to have a beautiful finish, particularly when used for sleeve packaging and the like.

[0006]

DISCLOSURE OF THE INVENTION The present invention exists semi-permanently in nature unless it is reused or incinerated, which is possessed by conventional heat-shrinkable films such as polyvinyl chloride, polypropylene, and polyethylene. There is no problem that the amount of heat generated when incinerated or high, or the problem that corrosive gas is generated during incineration, and as a shrinkable packaging material that was not obtained with conventional aliphatic polyester films Performance, especially uniaxially stretched film, in order to obtain a beautifully packaged state, it has good transparency, excellent mechanical strength, good balance of longitudinal and lateral shrinkage, and little shrinkage over time during product storage, biodegradability An object is to provide a uniaxially stretched aliphatic polyester film and a method for producing the same.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that there is a correlation between the stretching temperature and the impact strength when a specific aliphatic polyester resin is used. , A uniaxially stretched film having excellent transparency and mechanical strength can be obtained under a specific film forming method and a stretching condition, and further, shrinkage over time is small under a specific heat setting condition, and a shrinkage rate sufficient as a heat shrinkable material. The present invention has been found to have the following. That is, the present invention is mainly composed of 1,4-butanediol and succinic acid or succinic acid containing a comonomer such as adipic acid at 20% or less by mol.
The melt viscosity at 0 ° C and a shear rate of 100 (sec ^-1 ) is 4,000 to 100,000 poise and the melting point is 8
After molding an aliphatic polyester having a linear structure or a long-chain branched structure having a number average molecular weight of 30,000 or more at 0 to 120 ° C. by an extrusion film-forming method, it is 3 or more than the melting point of the resin.
Uniaxially stretched aliphatic polyester film having a haze of 2.0 to 10.0% and an impact strength of 2 kg · cm or more, which is obtained by stretching 3 to 8 times in the machine direction at a temperature lower by 5 to 50 ° C., and a method for producing the same. Is provided.

The contents of the present invention will be described in detail below. The aliphatic polyester referred to in the present invention is mainly 1,4-
The main component is a polyester synthesized from butanediol and succinic acid by a polycondensation method. To make the molecular weight sufficiently high, after synthesizing a relatively high molecular weight polyester prepolymer having a hydroxyl group at the end, These prepolymers are further polymerized by coupling with a coupling agent, and are disclosed in, for example, JP-A-4-189822 and JP-A-4-189823.
6-41288, 6-298920,
It is manufactured by the method disclosed in JP-A 7-53700, JP-A 7-70296, and JP-A 7-90043.

Specifically, the number-average molecular weight mainly consisting of 1,4-butanediol and succinic acid or succinic acid containing not more than 20 mol% of a comonomer such as adipic acid has a number average molecular weight of 20,000 or more and a melting point of 80. 100 ° C. or higher, preferably 85 ° C. or higher prepolymer 100 of aliphatic polyester
Linear structure (A), 1,4 obtained by reacting 0.1 to 5 parts by weight of diisocyanate, preferably an aliphatic one such as hexamethylene diisocyanate, with 1 part by weight. -Butanediol and succinic acid, or a succinic acid containing a comonomer such as adipic acid at 20 mol% or less as a main component, and a trifunctional or higher polyhydric alcohol such as glycerin, trimethylolpropane, or pentaerythritol, and citric acid Alternatively, at least one kind selected from the group consisting of trifunctional or higher functional oxycarboxylic acids (or their anhydrides) such as tartaric acid and trifunctional or higher functional polycarboxylic acids (or their anhydrides) such as trimetic anhydride. Prepolyester of polyester having a number average molecular weight of 20,000 or more obtained by adding polyfunctional component (0.1 to 2 mol%) and reacting Over may be mentioned long chain branching structure having a chain structure with diisocyanate and (B). In addition, 1,4-butanediol and succinic acid, or succinic acid containing 20 mol% or less of adipic acid as a main component, and the number average molecular weight of the polyester prepolymer of 20,000 or more, hexamethylene. Examples thereof include a long chain branched structure (C) having a number average molecular weight of 30,000 or more, which is obtained by reacting a diisocyanate trimer or a polyfunctional isocyanate such as a blocked isocyanate.

The aliphatic polyester resin used in the present invention has a melt viscosity at a temperature of 190 ° C. and a shear rate of 100 (sec ⁻¹ ) of 4,000 to 100,000 poises.
It is preferably 8,000 to 50,000 poise, has a number average molecular weight of 30,000 or more and a melting point of 80 to 120 ° C.
belongs to. When the melt viscosity is less than 4,000 poise, it becomes difficult to form a stable and uniform unstretched original sheet in extrusion molding. On the other hand, if it exceeds 100,000 poise, the motor load of the extruder becomes large and it becomes difficult to perform melt extrusion. The number average molecular weight is 30,000.
If it is less than the range, uniform stretching becomes difficult in the stretching process. Further, when the melting point is less than 80 ° C., the film is whitened or burned in the shrink tunnel during shrink wrapping, and the shrinkage with time during storage of the film in a product roll in a warehouse or the like becomes significantly large. On the other hand, when the melting point is higher than 120 ° C., it is necessary to set the set temperature in extrusion molding or stretching to a higher temperature, and in shrink wrapping, a high temperature is required to obtain a sufficient heat shrinkage ratio. Shrink wrapping does not give a tight and beautiful packaging.

The aliphatic polyester resin of the present invention comprises a linear structure (A) alone or a long chain branched structure ((B)).
And (C)) can be used alone, but can also be used as a mixture of the three.

As a comonomer for producing the aliphatic polyester of the present invention, adipic acid, sebacic acid, dodecanenic acid or the like can be used. The addition amount of these comonomers is in the range of having a melting point of 80 to 120 ° C., and is usually 25 mol% or less with respect to succinic acid.

In addition to the aliphatic polyester resin, other resins such as polycaprolactone, polylactic acid, polyhydroxy butyrate valerate, polyethylene wax, and polypropylene wax may be used as long as the object of the present invention is not impaired. , Polyvinyl alcohol, ethylene-vinyl acetate copolymer, ionomer, petroleum resin and the like can be mixed and used. Further, additives such as an antioxidant, a coloring preventing agent, a lubricant, an antiblocking agent, an antistatic agent, an antifogging agent, and a UV absorber are each effective as long as they do not hinder the object of the present invention. As a matter of course, it is appropriately used for the purpose of providing the action.

In the uniaxially stretched aliphatic polyester film of the present invention, additives such as the above-mentioned generally used antioxidants are added as needed, and 100 to 2 can be added by one extruder.
Melt kneading in the range of 50 ° C and extruding from a T-type die,
Thickness obtained by cooling with a chill roll 30-
A 300 μm flat unstretched raw fabric sheet is stretched 3 to 8 times at a temperature 35 to 50 ° C. lower than the melting point of the resin in the longitudinal direction (machine direction, parallel to the resin flow extruded when the raw fabric sheet is formed). 10 to 4 higher than the melting point of the resin.
It can be produced by heat setting at a temperature of 0 ° C. lower and a relaxation rate of 0.900 to 0.998.

If the melt-kneading temperature of the extruder is less than 100 ° C., the melting of the resin is insufficient, the motor load of the extruder is increased, and a uniform raw sheet cannot be obtained. At 250 ° C. or more, the resin deteriorates. The generation of gel and foreign matter increases, and it becomes difficult to form a stable film. The thickness of the uniaxially stretched film is determined depending on the thickness of the raw sheet and the stretching ratio, but is 10 to 100 μm, preferably 12 to 60 μm. If the stretched film is less than 10 μm, stable and uniform stretching is difficult, and the mechanical strength and heat resistance during shrink wrapping are poor. On the other hand, if it is 100 μm or more, a high temperature is required for setting the tunnel temperature when performing shrink wrapping, and the shrinkage is insufficient at the normal temperature setting, so that a beautiful shrinkage state cannot be obtained.

Further, the drawing in the present invention is carried out by preheating the hot roll drawing machine and from the melting point of the resin to the main hot roll by 35 to 5
At 0 ° C lower temperature, the peripheral speed ratio between the main heat roll and the cooling roll is 3
It is carried out by stretching the film in the machine direction by up to 5 times. When the stretching temperature is lower than the above temperature range, the shrinkage ratio becomes excessively large, and a beautiful shrinkage state can be obtained during shrink-wrapping, but the shrinkage in the longitudinal direction when left in an atmosphere at 35 ° C for 24 hours. If the rate exceeds 2% and the product is stored at room temperature for a long time in a warehouse or the like, it will shrink over time, which will impair its value as a product. On the other hand, at a temperature higher than the stretching temperature range, the orientation of the film by stretching is not sufficient,
The mechanical strength of the film, especially the impact strength is 2kg · cm
It is not preferable because the bag is easily broken at the time of packaging because it is decreased to less than 1. When the stretching temperature becomes higher, the shrinkage rate of the resulting film in the lateral direction (direction perpendicular to the flow of the resin extruded when making the original sheet) becomes minus several percent, which causes shrinkage packaging. Since the film is stretched, the finish of the film edge portion is deteriorated particularly in sleeve packaging.
In addition, the stretching ratio is preferably 3 to 8 times, and if it is less than 3 times, good transparency cannot be obtained, the shrinkage rate in shrink-wrapping is small, and the mechanical strength is poor. If it is 8 times or more, the resin used in the present invention easily breaks in the above stretching temperature range.
Stable and durable stretching becomes difficult, and the stretched film has large shrinkage over time, resulting in poor dimensional stability.

In the heat-setting treatment in the present invention, the heat-setting roll of the heat-roll drawing machine is heated to a temperature 10 to 40 ° C. lower than the melting point of the resin, and the peripheral speed ratio between the heat-setting roll and the cooling roll is
That is, the relaxation rate is 0.900 to 0.998. If the heat setting temperature is lower than the above temperature range or the relaxation rate is 0.998 or more, the effect of the heat treatment is small, the shrinkage with time becomes large, and the dimensional stability at low temperature is lacking. On the other hand, when the heat setting temperature is higher than the above temperature range or the relaxation rate is less than 0.900, the effect of heat setting becomes excessive, the orientation of the film disappears, the heat shrinkability in the longitudinal direction decreases, and The edge portion of the film in the horizontal direction stretches and a good shrink finish cannot be obtained.

Further, the uniaxially stretched film obtained by stretching and heat-setting treatment under the above conditions has a heat shrinkage ratio of 90 ° C. measured by JIS method Z1709, which is higher than that of the film not heat-treated. Although the shrinkability is reduced, this is an effect that is generated in order to obtain dimensional stability at low temperatures. The shrinkage rate at 100 ° C is as large as 40% or more, and a tight packaging finish can be obtained. It doesn't matter at all.

One of the features of the present invention is that the stretching is carried out at a temperature 35 to 50 ° C. lower than the melting point of the resin. The present inventors have found that the stretching temperature of the aliphatic polyester resin has a correlation with the impact strength without affecting the tensile strength of the film as seen in the experimental examples, and based on such findings, A film having excellent mechanical strength was obtained, and a film having excellent dimensional stability could be obtained by selecting the stretching temperature.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

The melt flow rate (MFR) is measured under condition 4 (test temperature 190 ° C., test load 2.) of JIS method K7210-1976 A method operation (manual cutting method).
16kgf, for polyethylene and polypropylene)
Obeyed. As the measurement sample, a pellet or a cut piece was used, which was previously dried under vacuum at 90 ° C. for 3 to 6 hours. Unless otherwise specified, stabilizers and other additives are included.

The number average molecular weight and the weight average molecular weight were measured by the GPC method as follows. Model used: Shodex GPC SYSTEM-11 (Showa Denko KK) Solvent: Chloroform Sample column: Shodex GPC K-801 (1), K-80M (2
, K-800P (1) Reference column: same as above Polymer solution: 0.1 wt%, 200 μl Operating conditions: Liquid flow rate 1.0 ml / min, column temperature 40 ° C., pressure 3
0kg / cm2 Detector: Shodex RI (4 × 10-5 RI / FS) Molecular weight standard: PMMA (Shodex STANDARD M-75)

The melting point was determined by using a DSC apparatus (manufactured by Rigaku Denki Co., Ltd.) in a sample of about 7 mg, at a heating rate of 10 ° C./min in nitrogen, and measuring the peak temperature.

The solution viscosity was measured using a capillary type rheometer manufactured by Toyo Seiki Co., Ltd. at a temperature of 190 ° C. and a shear rate of 10
It was measured at 0 sec-1. The nozzle diameter is 1.0 mm,
The viscosity at a shear rate of 100 sec -1 measured at a resin temperature of 190 ° C. using a nozzle of L / D = 10 was determined.

The method for evaluating the characteristic value and biodegradability of the film in the present invention is as follows. 1) Thickness: JIS method Z1709 2) Haze: JIS method K6714 3) Heat shrinkage rate: JIS method Z1709 4) Impact strength: JIS method P8134 5) Tensile strength: JIS method Z1707 6) Natural shrinkage rate: Long time film at room temperature Evaluation method measured as a guide for the shrinkage of the film that occurs over time when is stored in a warehouse. Film 200 x 200 m
m, sampled and left in a dryer at 35 ° C for 24
After measuring the vertical and horizontal dimensions after the elapse of time, the respective vertical and horizontal shrinkage rates are calculated by the following formulas. Natural shrinkage (%) = ((L ₁ −L ₀ ) / L ₀ ) × 100 where the dimensional length of the film at the time of sampling is L ₁ ,
Let the dimensional length of the film after 24 hours be L ₀ . 7) Calorific value of combustion: JIS method M8814 8) Biodegradability evaluation method: An evaluation method measured as a standard for biodegradation of the film in the natural world, assuming that no disposal treatment was performed. The film was embedded in soil and tested for biodegradability for 8 months. ◯: When the film is in a tattered state after 8 months with holes. X: When there is no hole even after 8 months and the shape of the film is firm.

Production Example 1 (Polybutylene succinate having a linear structure (FIG. 1, A))
Synthesis) Polycondensation reaction After the reactor of 80 liters was replaced with nitrogen, 18.3 kg of 1,4-butanediol and 22.4 kg of succinic acid were charged. The temperature was raised in a nitrogen stream, and the esterification reaction by dehydration condensation was performed at 190 to 220 ° C. for 3.5 hours, and then the nitrogen was stopped and the pressure was reduced to 20 to 2 mmHg for 3.5 hours. The sample collected has an acid value of 9.2 mg
/ G, the number average molecular weight was 5,160, and the weight average molecular weight was 10,670. Subsequently, 3.4 g of tetraisopropoxytitanium as a catalyst was added under a nitrogen stream at normal pressure. Raise the temperature to 15 ~ at a temperature of 215 ~ 220 ° C.
The deglycol reaction was performed under a reduced pressure of 0.2 mmHg for 5.5 hours. The collected sample has a number average molecular weight of 25,
200, and the weight average molecular weight was 65,400.
This prepolymer had a theoretical yield of 33.9 kg on the basis of an organic acid when condensed water was removed. ◎ Binding reaction In a reactor containing 33.9 kg of prepolymer, 3.4 g of phosphorous acid was added as a coloring inhibitor at 160 ° C., then 34 g of Irganox B225 as an antioxidant and 34 g of calcium stearate as a lubricant. In addition,
Stirring was continued for another 30 minutes. Then, 356 g of hexamethylene diisocyanate (1.05 parts by weight relative to 100 parts by weight of prepolymer) was added to the reactor with stirring, and
1.5 hours at 0-200 ° C, then 200 minutes for 30 minutes
Decoupling was performed under a reduced pressure of 400 mmHg, and a coupling reaction was carried out by allowing the mixture to stand for 1.5 hours with stirring (3.5 hours in total).
The viscosity increased sharply, but no gel formed. The reaction product is operated by operating the gear pump under the kettle,
The four strands were extruded into water with a die of 00 ° C, and cut into pellets with a rotary cutter. The yield of polyester after vacuum drying at 90 ° C. for 6 hours was 32 kg. This polyester (A) is in the form of white pellets,
Melting point 115.6 ° C, number average molecular weight 69,800, weight average molecular weight 167,500, MFR (190 ° C,
2.16 kg) was 2.96 g / 10 minutes. Also,
The melt viscosity at a shear rate of 100 sec-1 (190 ° C) is 12,000 poise, and the heat value of combustion is 5,60.
It was 0 kcal / kg.

Test Example The resin obtained in Production Example 1 was used in a single extruder for 120 to 18
Melt kneading at 0 ° C., extruding with a single-layer T die kept at 180 ° C. so as to come into contact with a cooling roll, and roll temperature 55
At 100 ° C. and a take-up speed of 2.5 m / min, a 100 μm-thick original fabric sheet was obtained. This sheet was stretched 4.0 times in the machine direction by passing it between hot rolls at the temperatures shown in Table 1 to obtain a uniaxially stretched film having a thickness of 25 μm. Table 1 shows the impact strength and tensile strength of the obtained film. As is clear from Table 1, there is a correlation between the stretching temperature and the impact strength.

[0028]

[Table 1]

Example 1 The linear polyester polybutylene succinate (A) aliphatic polyester resin obtained in Production Example 1 was melt-kneaded at 120 to 180 ° C. in one extruder and kept at 180 ° C. Extruded by a layer T-die so as to be in contact with a cooling roll, the roll temperature was 55 ° C., the take-up speed was 4.2 m / min, and the thickness was 60.
An original sheet of μm was obtained. This sheet is stretched 4.0 times in the machine direction by passing it between hot rolls at 80 ° C.
After heat treatment at a relaxation rate of 0.920 with a heat setting roll at 00 ° C., a uniaxially stretched film having a thickness of 15 μm was obtained. The characteristic values of the obtained stretched film are shown in Table 2. With this film, roll-shaped shoji paper can be used with a margin of 15 in the longitudinal direction of the film.
% Temporarily in a sleeve form and passed through a shrink tunnel with a set temperature of 80 ° C and a transit time of 4 seconds. The film had no whitening or burns, and there was a tight feeling in the longitudinal direction of the film. The shrinkage of the film edge in the direction was also good, resulting in a beautiful packaging finish. The product roll of this film was allowed to stand at room temperature for 3 months, but no reduction in the flatness of the film, reduction of the film width, winding tightness of the roll, etc. were observed.

Example 2 The aliphatic polyester resin obtained in Production Example 1 was melt-kneaded in one extruder at 120 to 180 ° C., and contacted with a cooling roll by a single layer T die kept at 180 ° C. Extrusion, roll temperature 55 ℃, take-off speed 2.8 m / min,
A raw sheet having a thickness of 80 μm was obtained. This sheet at 65 ℃
The film is stretched 3.2 times in the machine direction by passing it between the heat rolls, and the relaxation rate is 0.920 by the heat setting roll at 75 ° C.
After the heat treatment of, a uniaxially stretched film having a thickness of 25 μm was obtained. The characteristic values of the obtained stretched film are shown in Table 2. Using this film, collect 4 canned pet foods,
When the product was temporarily packaged in the form of a sleeve with a margin ratio of 13% in the longitudinal direction and passed through a shrinking tunnel with a set temperature of 70 ° C. and a passage time of 4 seconds, the four cans were in close contact and a tight finish was obtained. Further, even when the packaged product was packed in a cardboard box, the film and the seal portion were not broken. Furthermore, when the product roll of this film was left to stand at room temperature for 3 months, the flatness of the film was not reduced, the width of the film was reduced, the winding tightness of the roll was not observed at all.

Example 3 The aliphatic polyester resin obtained in Production Example 1 was melt-kneaded at 120 to 180 ° C. in one extruder, and contacted with a cooling roll by a single layer T die kept at 180 ° C. Extrusion, roll temperature 55 ° C., take-off speed 0.8 m / min,
A raw sheet having a thickness of 280 μm was obtained. 80 this sheet
The film is stretched 4.9 times in the machine direction by passing it between heat rolls at 90 ° C., and the relaxation rate is 0.99 by the heat setting rolls at 90 ° C.
After the heat treatment of 0, a uniaxially stretched film having a thickness of 57 μm was obtained. The characteristic values of the obtained stretched film are shown in Table 2. Using this film, 295 x 2 containing 10 kg of packing material
35% x 95 mm cardboard box with 11% margin in the vertical direction
Then, the product was temporarily packaged in a sleeve form and passed through a shrinking tunnel with a set temperature of 85 ° C. and a passage time of 4 seconds, resulting in a tight finish. Further, even if a slight shock was given when stacking the packages in several stages, the film and the seal portion were not broken.

Example 4 The aliphatic polyester resin obtained in Production Example 1 was melt-kneaded in one extruder at 120 to 180 ° C., and contacted with a cooling roll by a single layer T die kept at 180 ° C. Extrusion, roll temperature 55 ° C., take-off speed 3.0 m / min,
A raw sheet having a thickness of 75 μm was obtained. This sheet at 70 ℃
The film is stretched 3.0 times in the machine direction by passing it between the heat rolls, and the relaxation rate is 0.995 by the heat setting roll at 85 ° C.
After the heat treatment of, a uniaxially stretched film having a thickness of 25 μm was obtained. The characteristic values of the obtained stretched film are shown in Table 2. This film was used to temporarily wrap a video tape in the longitudinal direction of the film in a sleeve form with a margin ratio of 15%, and passed through a shrink tunnel with a set temperature of 75 ° C and a transit time of 4 seconds, resulting in a tight finish. It was Furthermore, when the roll of this film was left at room temperature for 3 months, the flatness of the film was not reduced, the width of the film was reduced, and the winding tightness of the roll was not observed at all.

Comparative Example 1 A uniaxially stretched film was produced in the same manner as in Example 1 except that the stretching ratio was 2.5 times in the machine direction, and the characteristic values are shown in Table 2. The transparency, heat shrinkability and mechanical strength were significantly reduced. A roll-shaped shoji paper was temporarily wrapped in a sleeve form with a margin of 15% in the longitudinal direction of the film and passed through a shrink tunnel with a set temperature of 80 ° C and a transit time of 4 seconds. It did not shrink and no beautiful packaging finish was obtained.

Comparative Example 2 An attempt was made to obtain a uniaxially stretched film in the same manner as in Example 1 except that the stretching ratio was 8.8 in the longitudinal direction. It broke and stable stretching did not continue.

Comparative Example 3 A uniaxially stretched film was produced in the same manner as in Example 2 except that the stretching temperature was 55 ° C., and its characteristic values are shown in Table 2.
The values of thermal shrinkage and natural shrinkage were large. Using this film, 4 canned pet foods were accumulated and temporarily wrapped in a sleeve form with a margin ratio of 13% in the longitudinal direction, and passed through a shrink tunnel with a set temperature of 70 ° C and a transit time of 4 seconds. The four cans were in close contact and had a tight finish. However, when the product roll of this film was allowed to stand at room temperature and observed after 3 months, the flatness of the film was reduced, the film width was reduced, and the roll was tightly wound, resulting in loss of product value.

Comparative Example 4 A uniaxially stretched film was produced in the same manner as in Example 2 except that the stretching temperature was 90 ° C., and its characteristic values are shown in Table 2.
The impact strength and tensile strength showed low values. Using this film, 4 canned pet foods were accumulated and temporarily packed in a sleeve form with a margin ratio of 13% in the vertical direction, and the set temperature was 70%.
After passing through a shrink tunnel having a passage time of 4 seconds at 40 ° C., there was no tight feeling in the shrink state, and further, the film edge portion in the lateral direction was stretched, resulting in a poor-looking finish. Also, when this package was packed in a cardboard box, the film broke and the canned pieces fell apart.

Comparative Example 5 The heat setting treatment temperature was 70 ° C. and the heat setting relaxation rate was 0.999.
A uniaxially stretched film was produced in the same manner as in Example 4 except that the above was used, and the characteristic values thereof are shown in Table 2. The values of thermal shrinkage and natural shrinkage were large. This film was used to temporarily wrap a video tape in the longitudinal direction of the film in a sleeve form with a margin ratio of 15%, and passed through a shrink tunnel with a set temperature of 75 ° C and a transit time of 4 seconds, resulting in a tight finish. It was However, when the product roll of this film was left at room temperature and observed after 3 months, the flatness of the film was lowered, the film width was reduced, and the roll was tightly wound, resulting in loss of product value.

Comparative Example 6 The heat setting treatment temperature was 70 ° C. and the heat setting relaxation rate was 0.999.
A uniaxially stretched film was produced in the same manner as in Example 4 except that the above was used, and the characteristic values thereof are shown in Table 2. The impact strength and tensile strength showed low values. This film was used to temporarily wrap a video tape in the longitudinal direction of the film in the form of a sleeve with a margin of 15% and passed through a shrink tunnel with a set temperature of 75 ° C and a transit time of 4 seconds. Moreover, the edge of the film in the lateral direction stretched, resulting in an unattractive finish. Furthermore, when several layers of this package were stacked and packed in a cardboard box, film tearing was observed.

Production Example 2 (Synthesis of polybutylene / succinate / adipate copolymer having long-chain branched structure (FIG. 1, B)) ◎ Polycondensation reaction 1,4-butane was substituted in a reactor of 80 liters with nitrogen. Diol 17.4 kg, succinic acid 17.3 kg, adipic acid 5.4 kg (succinic acid to adipic acid mol%
Ratio, 80:20), trimethylolpropane 126g
(0.5 mol% with respect to succinic acid) was charged. The temperature is raised under a nitrogen stream and the temperature is set at 190 to 220 ° C for 3.5 hours.
2. Further stop nitrogen, and under a reduced pressure of 20 to 2 mmHg.
The esterification reaction by dehydration condensation was performed for 5 hours. The sample collected had an acid value of 9.6 mg / g, a number average molecular weight of 6,100, and a weight average molecular weight of 12,20.
It was 0. Subsequently, 2.0 g of tetraisopropoxy titanium as a catalyst was added under a nitrogen stream under normal pressure. Raise the temperature to 15 ~ 0.2mmH at 210 ~ 220 ℃
The deglycol reaction was carried out under a reduced pressure of g for 6.5 hours. The sample collected had a number average molecular weight of 28,250 and a weight average molecular weight of 68,910. This prepolymer has a theoretical yield of 3 when the condensed water is removed.
It was 2.6 kg. ◎ Coupling reaction In a reactor containing 32.6 kg of prepolymer, 3.3 g of phosphorous acid was added at 160 ° C as an anti-coloring agent, then 34 g of Irganox 1010 as an antioxidant and 34 g of calcium stearate as a lubricant. In addition,
Stirring was continued for another 30 minutes. Next, 253 g of hexamethylene diisocyanate (0.775 parts by weight based on 100 parts by weight of prepolymer) was added to the reactor with stirring, and 1
2 hours at 60-190 ° C, then 200-4 for 30 minutes
The defoaming under a reduced pressure of 00 mmHg and the coupling reaction of standing for 1.5 hours without stirring (total 3.5 hours) were performed. The viscosity increased sharply, but no gel formed. This reaction product is operated by a gear pump under the kettle to obtain a temperature of 190 to 20
The four strands were extruded into water with a die at 0 ° C. and cut into pellets with a cutter. The yield of polyester after vacuum drying at 70 ° C. for 6 hours was 30 kg.
This polyester copolymer (B) is in the form of white pellets,
Melting point 92.7 ° C, number average molecular weight 45,200, weight average molecular weight 226,300, MFR (190 ° C, 2.
16 kg) was 2.2 g / 10 minutes. Also, the melt viscosity at a shear rate of 100 sec-1 (190 ° C) is 9,000 poise, and the heat value of combustion is 5,700 kc.
It was al / kg.

Example 5 The aliphatic polyester resin of the polybutylene / succinate / adipate copolymer (B) having the long-chain branched structure obtained in Production Example 2 was melt-kneaded at 120 to 180 ° C. with one extruder. A single-layer T die kept at 170 ° C. was extruded so as to come into contact with the cooling roll, and a roll sheet having a thickness of 80 μm was obtained at a roll temperature of 50 ° C. and a take-up speed of 2.8 m / min. This sheet was stretched 3.2 times in the machine direction by passing it between heat rolls at 60 ° C., and after heat treatment at a relaxation rate of 0.920 by a heat setting roll at 70 ° C., a uniaxially stretched film having a thickness of 25 μm was obtained. . The characteristic values of the obtained stretched film are shown in Table 2. Using this film, 4 canned pet foods were accumulated and temporarily wrapped in a sleeve form with a margin ratio of 13% in the longitudinal direction, and then passed through a shrink tunnel with a set temperature of 65 ° C and a transit time of 4 seconds. The four cans were in close contact and had a tight finish. Further, even when the packaged product was packed in a cardboard box, the film and the seal portion were not broken. Furthermore, when the product roll of this film was left to stand at room temperature for 3 months, the flatness of the film was not reduced, the width of the film was reduced, and the roll was not tight.

Production Example 3 (Synthesis of polybutylene succinate (FIG. 1, C) having a relatively long long-chain branched structure) ◎ Polycondensation reaction After replacing the 80-liter reactor with nitrogen, 1,4-butanediol 20 was added. 0.0 kg and 25.0 kg of succinic acid were charged. The temperature is raised under a nitrogen stream, and the temperature is set at 190 to 220 ° C for 3.5 hours, and then nitrogen is stopped to set the temperature to 20 to 1.2 mmH.
The esterification reaction by dehydration condensation was carried out for 2.5 hours under a reduced pressure of g. The collected sample has an acid value of 23 m
The number average molecular weight was 5,200 and the weight average molecular weight was 7,800. Subsequently, 2.0 g of tetraisopropoxy titanium as a catalyst was added under a nitrogen stream under normal pressure. Raise the temperature to 1.5 at 210-220 ° C.
The deglycolization reaction was performed for 4.5 hours under a reduced pressure of 0.7 mmHg. The sample collected has a number average molecular weight of 2
The weight average molecular weight was 4,000 and was 47,740. This prepolymer had a theoretical yield based on an organic acid of 36.4 kg when condensed water was removed. ◎ Bonding reaction In a reactor containing 36.4 kg of prepolymer, 9.0 g of phosphorous acid was added as an anti-coloring agent at 160 ° C., then 36 g of Irganox B225 as an antioxidant and 36 g of calcium stearate as a lubricant. In addition,
Stirring was continued for another 30 minutes. Next, 291 g of hexamethylene diisocyanate (0.8 parts by weight based on 100 parts by weight of prepolymer) was added with stirring, and the mixture was heated at 160 ° C. for 20 hours.
After stirring for a minute, 291 g of trimethylolpropane hexamethylene diisocyanate adduct (75% ethyl acetate solution of active ingredient, 0.8 parts by weight per 100 parts by weight of prepolymer, a product of Nippon Polyurethane Industry Co., Ltd.) Coronate HL) is further added, and 180 to 200
The reaction was carried out at 2 ° C. for 2 hours. The viscosity increased rapidly but no gel formed. This reaction product was extruded into water through a gear pump and a die and cut into pellets with a rotary cutter. After vacuum drying at 90 ° C. for 6 hours, the aliphatic polyester resin (C) of the present invention was obtained. Yield 32k
g. This polyester (C) is in the form of white pellets, has a melting point of 116.1 ° C. and a number average molecular weight of 65,13.
0, weight average molecular weight 186, 440, MFR (190
C., 2.16 kg) was 3.5 g / 10 minutes. Further, the melt viscosity at a shear rate of 100 sec-1 (190 ° C) is 12,000 poise, and the combustion heat value is 5,
It was 600 kcal / kg.

Example 6 The aliphatic polyester resin of polybutylene succinate (C) having a relatively long long-chain branched structure obtained in Production Example 3 was melt-kneaded at 120 to 180 ° C. with one extruder, and 180
Extruded by a single layer T-die kept at ℃ so as to come into contact with a cooling roll, roll temperature 55 ℃, take-up speed 4.0 m / mi
With n, a raw sheet having a thickness of 60 μm was obtained. This sheet was passed between hot rolls at 80 ° C. to obtain 4.0 in the longitudinal direction.
The film was stretched twice and heat-treated with a heat setting roll at 100 ° C. at a relaxation rate of 0.920 to obtain a uniaxially stretched film having a thickness of 15 μm. The characteristic values of the obtained stretched film are shown in Table 2. A roll-shaped shoji paper was temporarily wrapped in a sleeve form with a margin of 15% in the longitudinal direction of this film and passed through a shrink tunnel with a set temperature of 80 ° C and a transit time of 4 seconds. There is no burn or burn, the film has a tight feeling in the longitudinal direction, and the shrinkage of the film edge in the lateral direction is good, resulting in a beautiful packaging finish. The product roll of this film was allowed to stand at room temperature for 3 months, but no reduction in the flatness of the film, reduction of the film width, winding tightness of the roll, etc. were observed.

[0043]

[Table 2]

[0044]

As described above, the film of the present invention has microbial decomposability, has a low combustion calorific value as compared with polyolefin resins such as polyethylene and polypropylene even when heat-treated, and has a problem of disposal. Few. Also,
Since it is stretched at a relatively low temperature, it has excellent mechanical strength typified by transparency and impact strength. Furthermore, heat-setting treatment reduces shrinkage over time and provides excellent dimensional stability. Even when stored in a warehouse, it is suitable as a shrink-wrapping material without losing the commercial value.

[Brief description of drawings]

FIG. 1 is a schematic view of a skeletal structure of a resin shown in an example.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08J 5/18 CFD C08J 5/18 CFD // B29K 67:00 B29L 7:00 (72) Inventor Mitsuhiro Imaizumi 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa, Showa Denko Ltd., Kawasaki Plastics Research Laboratory (72) Inventor Takashi Fujimaki 3-20, Kandanishiki-cho, Chiyoda-ku, Tokyo Sho Awa Co., Ltd.

Claims (4)

[Claims] 1. A temperature of 190 ° C. and a shear rate of 10 mainly synthesized from 1,4-butanediol and succinic acid or succinic acid containing 20 mol% or less of adipic acid or the like.
Melt viscosity at 0 (sec ^-1 ) is 4,000 to 10
After molding an aliphatic polyester having a linear structure or a long-chain branched structure having a melting point of 80 to 120 ° C. and a number average molecular weight of 30,000 or more by an extrusion film-forming method, Haze 2.0 to 10., which is stretched 3 to 8 times in the machine direction at a temperature 35 to 50 ° C. lower than the melting point.
Uniaxially stretched aliphatic polyester film having 0% and impact strength of 2 kg · cm or more. 2. After the drawing, a heat treatment is applied at a temperature lower than the melting point by 10 to 40 ° C. and a relaxation rate of 0.900 to 0.998.
The uniaxially stretched aliphatic polyester film according to claim 1, which has a longitudinal shrinkage of 2% or less when stored in a 35 ° C. atmosphere for 24 hours and has excellent dimensional stability during product storage. 3. 100 measured by JIS method Z1709
The uniaxially stretched aliphatic polyester film according to claim 1 or 2, which has a shrinkage in the longitudinal direction at 40 ° C of 40% or more. 4. A temperature of 190 ° C. and a shear rate of 10 mainly synthesized from 1,4-butanediol and succinic acid or succinic acid containing 20 mol% or less of adipic acid or the like.
Melt viscosity at 0 (sec ^-1 ) is 4,000 to 10
After molding a resin made of an aliphatic polyester having a linear structure or a long-chain branched structure having a melting point of 80 to 120 ° C. and a number average molecular weight of 30,000 or more by an extrusion film-forming method. , 35-35 than the melting point of the resin
It is stretched 3 to 8 times in the machine direction at a temperature lower by 50 ° C., and the relaxation rate is 0.900 to 0.998 at a temperature 10 to 40 ° C. lower than the melting point.
Haze 2.0 to 10.
A method for producing a uniaxially stretched aliphatic polyester, which has 0% impact strength, 2 kg · cm or more, and a longitudinal shrinkage of 2% or less when stored in an atmosphere at 35 ° C. for 24 hours.