JP6138409B2 - Method for producing stretched thermoplastic polyester resin sheet - Google Patents

Description

  The present invention relates to a method for producing a stretched thermoplastic polyester resin sheet.

  Conventionally, for a stretched thermoplastic polyester resin sheet having excellent tensile strength, tensile elastic modulus and heat resistance, the thermoplastic polyester resin sheet in an amorphous state is placed near the glass transition temperature of the thermoplastic polyester resin. There has been proposed a method of manufacturing by drawing through a pair of rolls in a predetermined temperature range and stretching (for example, see Patent Document 1).

  However, in this method, shrinkage (necking) in the width direction of the sheet becomes large before and after drawing and drawing, so that the width of the raw material must be widened to obtain a product with the required sheet width, and the manufacturing efficiency is deteriorated. However, when the sheet is pulled, the sheet receives a shearing force from the roll and partially generates heat. Therefore, there is a problem that uneven shrinkage occurs when the sheet passes through the next process.

Japanese Patent No. 3804003

  Under such circumstances, the object of the present invention is to reduce the shrinkage (necking) of the sheet in the width direction due to drawing and drawing, and to generate uneven stretching in the drawing direction in the process following the drawing and drawing process. An object of the present invention is to provide a method for producing a high-quality stretched thermoplastic polyester resin sheet efficiently.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be achieved by cooling the stretched sheet after drawing and drawing, and have made the present invention based on this finding. It was.

That is, according to the first invention of the present invention, an amorphous thermoplastic polyester resin sheet is obtained by changing the glass transition temperature of the thermoplastic polyester resin from −30 ° C. to the glass transition temperature of the thermoplastic polyester resin. Subsequent to the drawing and drawing treatment of drawing through a pair of drawing rolls having a temperature of 30 ° C. to the glass transition temperature of the thermoplastic polyester resin + 20 ° C., the entire width direction of both sides of the drawn sheet was put into the refrigerant. There is provided a method for producing a stretched thermoplastic polyester-based resin sheet, which is heat-fixed after a cooling treatment for sandwiching the stretched sheet surface with a cooling roll .

  According to the second invention of the present invention, in the first invention, the amorphous thermoplastic polyester resin sheet has a crystallinity of less than 10% as measured by a differential scanning calorimeter. A method for producing a stretched thermoplastic polyester resin sheet is provided.

  According to the third invention of the present invention, in the first or second invention, the stretched thermoplastic polyester resin sheet is heat-set at a temperature higher than the stretching temperature. A manufacturing method is provided.

  According to a fourth aspect of the present invention, there is provided a method for producing a stretched thermoplastic polyester resin sheet according to any one of the first to third aspects, wherein the thermoplastic polyester resin is polyethylene terephthalate. Provided.

According to a fifth aspect of the present invention, there is provided the method for producing a stretched thermoplastic polyester resin sheet according to any one of the first to fourth aspects, wherein annealing is performed subsequent to the heat setting treatment. The

  According to the manufacturing method of the present invention, shrinkage (necking) in the width direction of the sheet due to drawing and drawing can be reduced, and occurrence of uneven stretching in the drawing direction in the step following the drawing and drawing step can be suppressed. There is an advantage that a high-quality stretched thermoplastic polyester resin sheet can be produced efficiently.

  In the method of the present invention, a thermoplastic polyester resin sheet in an amorphous state is drawn into a pair of glass transition temperatures of −30 ° C. to glass transition temperature of the thermoplastic polyester resin + 20 ° C. It is important to cool the stretched sheet following the drawing and stretching process of stretching between the rolls and then heat-set, and further to perform the annealing process following the heat-fixing process.

  Examples of the thermoplastic polyester resin of the resin material in the thermoplastic polyester resin sheet include, for example, polyalkylene terephthalate such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyglycolic acid, poly (L-lactic acid), poly (3-hydroxybutyrate), poly (3-hydroxybutyrate / hydroxyvalerate), poly (ε-caprolactone), polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polybutylene succinate / lactic acid, Polybutylene succinate / carbonate, polybutylene succinate / terephthalate, polybutylene adipate / terephthalate, polytetramethyladipate / terephthalate, polybutylene Succinate / adipate / terephthalate, and the like, preferably among them excellent heat resistance polyethylene terephthalate.

  The thermoplastic polyester resin sheet is preferably in an amorphous state, and further preferably has a crystallinity of less than 10%, particularly less than 5%. The crystallinity is measured by, for example, a differential scanning calorimeter.

  If the temperature of the thermoplastic polyester resin sheet during drawing is too low, the stretched thermoplastic polyester resin sheet will be whitened, too hard and will not tear, and will not be pulled out. It is preferable to preheat the glass transition temperature of the plastic polyester resin to a temperature of -30 ° C or higher.

  When the temperature of the pair of drawing rolls during drawing and drawing is too low, the temperature of the drawn thermoplastic polyester resin sheet decreases and the sheet is whitened. If it is too high, the resin temperature rises due to frictional heat during drawing and the like, and the molecular orientation becomes insufficient. Therefore, the glass transition temperature of the thermoplastic polyester resin is preferably −30 ° C. or higher, and the glass transition temperature +20 It is preferable to adjust the temperature to less than ° C., more preferably above the glass transition temperature of the thermoplastic polyester resin and less than the glass transition temperature + 10 ° C.

  Also, when drawing and stretching, if a pair of rolls are rotated so that their opposing surfaces are in the drawing direction, the resistance during drawing and drawing is reduced, and undulation of the stretched thermoplastic polyester resin sheet occurs. Can be suppressed.

  The draw ratio is not particularly limited, but if it is too low, it is difficult to obtain a sheet excellent in tensile strength and tensile elastic modulus, and if it is too high, the sheet tends to break during stretching. -9 times is preferable, More preferably, it is 4-8 times.

  The stretched thermoplastic polyester resin sheet thus stretched may be further stretched in the drawing stretching direction at a temperature higher than the temperature of the drawing roll, for example, uniaxially stretching.

  The stretch ratio at the time of further stretching is not particularly limited, but if the stretch ratio is too low, it is difficult to obtain a sheet excellent in mechanical strength such as tensile strength and tensile elastic modulus, and is too high. However, since it becomes easy to produce a fracture | rupture of a sheet | seat at the time of extending | stretching, 1.1-3 times are preferable, More preferably, it is 1.2-2 times. Further, the total draw ratio of this further drawing and the previous drawing is preferably 2.5 to 10 times for the same reason.

  In addition, the stretched thermoplastic polyester resin sheet may be stretched in a direction perpendicular to the direction of the above-described drawing and stretching, and in this case, it becomes biaxial stretching, and even if it is bent along the drawing and stretching direction, the strength decreases such as generation of cracks. Disappears.

  In the stretched thermoplastic polyester resin sheet, if the degree of crystallization is low, the heat resistance and mechanical strength are lowered, and if it is high, it tends to break, so the degree of crystallization is preferably 20 to 50%, preferably 30 to 45. % Is more preferable.

  In the method of the present invention, it is important that the stretched sheet obtained by the drawing and stretching process as described above is subsequently subjected to a cooling process. The cooling process suppresses heat generation due to the shearing force received from the roll of the sheet when the original sheet is pulled out, thereby causing crystallization of the sheet to proceed with the heat generation and uneven shrinkage in the subsequent steps. It becomes possible to suppress the occurrence of the sheet and the difficulty of pulling out the sheet.

  The cooling treatment is preferably performed on both sides of the stretched sheet. The cooling method is preferably such that the sheet surface is exposed to the refrigerant. For example, the refrigerant is preferably blown, sprayed, or sprayed from the cooling nozzle toward the sheet surface, and the refrigerant is put in the refrigerant. It is preferable to sandwich the sheet surface with a cooling roll. These cooling methods may be used alone or in combination, and may be appropriately performed, for example, cooling by a cooling roll following cooling by the cooling nozzle.

  Examples of the refrigerant include air, water, oil, and the like, and it is preferable to blow air directly on the sheet surface. The cooling roll is preferably filled with a cooling liquid such as water or oil.

  In the method of the present invention, the stretched thermoplastic polyester resin sheet is then heat-set in order to improve heat resistance and mechanical strength.

  If the heat setting temperature is lower than the drawing stretching temperature, the crystallization of the thermoplastic polyester resin will not proceed, so the heat resistance will not improve.If the temperature becomes higher than the rise temperature of the melting peak of the thermoplastic polyester resin, the thermoplastic polyester resin will Since it melt | dissolves, extending | stretching (orientation) lose | disappears and mechanical strength etc. fall, it is preferable that it is below the rising temperature of this melting peak. A heating means is not specifically limited, For example, a hot air, a heater, etc. may be used.

  In addition, when heat-fixing, the stretched thermoplastic polyester resin sheet is stretched if a large tension is applied, and it is not tensioned or shrinks in a very small state. It is preferable that the length is not substantially changed, and it is preferable that no pressure is applied to the stretched thermoplastic polyester resin sheet. When heat-fixing a short sheet, it is preferable to fix both ends in a state where no load is applied.

  For example, it is preferable to heat-set so that the length of the stretched thermoplastic polyester resin sheet that has been heat-fixed is 0.95 to 1.1 of the length of the stretched thermoplastic polyester-based resin sheet before heat setting. .

  The time for heat setting is not particularly limited, but is generally 10 seconds to 10 minutes, although it varies depending on the thickness of the stretched thermoplastic polyester resin sheet and the heat setting temperature.

  The stretched thermoplastic polyester resin sheet that has been heat-fixed further has a rising temperature range of the crystallization peak of the thermoplastic polyester resin in a differential scanning calorimetry curve measured at a glass transition temperature to a temperature rising rate of 1 ° C./min. Thus, it is preferable to anneal in a state where substantially no tension is applied.

  By annealing, the stretched thermoplastic polyester resin sheet has good mechanical properties such as elastic modulus, and the mechanical properties such as elastic modulus do not decrease even when heated to a temperature above the glass transition temperature, and The shrinkage rate can be kept low.

  In addition, since the stretched thermoplastic polyester resin sheet is stretched when a large tension is applied thereto, it is preferable to anneal the stretched thermoplastic polyester resin sheet in a state in which no tension is applied to the stretched thermoplastic polyester resin sheet.

  That is, it is preferable to anneal so that the length of the annealed stretched thermoplastic polyester resin sheet is 1.0 or less of the length of the stretched thermoplastic polyester resin sheet before annealing.

  Therefore, when the stretched thermoplastic polyester resin sheet is continuously annealed while being moved in a heating chamber by a roll such as a pinch roll, the feed rate ratio of the stretched thermoplastic polyester resin sheet on the inlet side and the outlet side is set to 1. It is preferable to anneal by setting it to be 0 or less.

  Moreover, when annealing a short sheet, it is preferable to open both ends so that no load is applied.

  The heating method at the time of annealing is not particularly limited, and examples thereof include a method of heating with hot air or a heater.

  The time for annealing is not particularly limited and varies depending on the thickness of the stretched thermoplastic polyester resin sheet and the annealing temperature, but is generally preferably 10 seconds or more, more preferably 30 seconds to 5 minutes, and still more preferably 1-2. Minutes.

  EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not limited at all by these examples.

(Example 1-5)
A polyethylene terephthalate original fabric (made by Teijin Kasei Co., Ltd., trade name “A-PET sheet FR”, crystallinity 4%) having a thickness of 1.0 mm and a width of 200 mm is supplied to a stretching apparatus (manufactured by Kyowa Engineering Co., Ltd.). After preheating to ° C., a pair of drawing rolls (Φ200 mm, 400 mm, roll interval 0.2 mm) heated to 80 ° C. was drawn at a linear velocity of 2.0 m / min and stretched.
Subsequently, one or both of the cooling devices A and B shown below were disposed on both surfaces of the stretched sheet under the cooling conditions shown in Table 1 below, and the stretched sheet was pulled out while cooling.
Next, the drawn stretched sheet was passed through a hot air heating tank heated to 170 ° C. at an outlet speed of 2.5 m / min to obtain a stretched polyethylene terephthalate sheet.
The same test was performed 5 times, and the average value was calculated | required about the dimension and the characteristic by making each extending | stretched polyethylene terephthalate sheet | seat obtained each test piece. The results are shown in Table 1.
As for the tensile strength, the maximum value and the minimum value between the test pieces were 16 to 21 MPa in each example and the opening was small, and the physical properties were stable.

<Cooling device A>
A nozzle having an opening (400 mm × 20 mm) is arranged vertically at a position of 50 mm from the sheet surface so that air from the opening hits the sheet surface at a right angle. The nozzle is connected to a blower fan, and the rotational speed of the fan can be varied from 0 to 2850 rpm (air volume 0 to 56 m ³ / min), so that the air volume from the nozzle can be adjusted.

<Cooling device B>
A pair of oil-filled cooling rolls having a diameter of 50 mm and a surface length of 400 mm capable of temperature control are brought into contact with the sheet surface and rotated in synchronization with the sheet speed.

Comparative Example 1
In Example 1, a stretched polyethylene terephthalate sheet was obtained in the same manner as in Example 1 except that no cooling device was used.
The same test was performed 5 times, and the average value was calculated | required about the dimension and the characteristic by making each extending | stretched polyethylene terephthalate sheet | seat obtained each test piece. The results are shown in Table 1.
As for the tensile strength, the maximum value and the minimum value between the test pieces were as large as 37 MPa, and the physical properties were not stable.

  From this, it can be seen that the stretched sheets of the examples can reduce the shrinkage in the width direction while maintaining the strength and have stable physical properties as compared with those of the comparative example.

  The production method of the present invention reduces the shrinkage (necking) in the width direction of the sheet due to drawing and drawing, and can suppress the occurrence of uneven stretching in the drawing direction in the step following the drawing and drawing step. It is very useful in industry.

Claims (5)

Amorphous thermoplastic polyester resin sheet is stretched by passing between a pair of drawing rolls having a glass transition temperature of −30 ° C. of the thermoplastic polyester resin to a glass transition temperature of the thermoplastic polyester resin of + 20 ° C. The drawing heat is characterized in that after the drawing and drawing treatment, the whole widthwise surface of both sides of the drawn sheet is subjected to a cooling treatment for sandwiching the drawn sheet surface with a cooling roll containing a refrigerant and then heat-fixed. A method for producing a plastic polyester resin sheet.   The method for producing a stretched thermoplastic polyester resin sheet according to claim 1, wherein the amorphous polyester resin sheet has a crystallinity of less than 10% as measured by a differential scanning calorimeter.   The method for producing a stretched thermoplastic polyester resin sheet according to claim 1 or 2, wherein the stretched thermoplastic polyester resin sheet is heat-set at a temperature higher than the stretching temperature.   The method for producing a stretched thermoplastic polyester resin sheet according to any one of claims 1 to 3, wherein the thermoplastic polyester resin is polyethylene terephthalate.   The method for producing a stretched thermoplastic polyester resin sheet according to any one of claims 1 to 4, wherein annealing is performed subsequent to the heat setting treatment.