JP4960660B2 - 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, and more particularly to a method for producing a stretched thermoplastic polyester resin sheet having excellent tensile strength, tensile elastic modulus, heat resistance and the like.

Conventionally, a method for producing a transparent crystalline polymer sheet having a smooth surface and a high strength and elastic modulus by pultrusion has been studied. For example, crystals such as polyethylene, polypropylene, polyacetal resin, nylon, etc. The temperature of the base sheet of the differential polymer calorimetry melting curve is not exceeded the deformation starting temperature when the sheet is heated at a rate of temperature increase of 1 ° C./min with a 10 MPa load applied to the sheet. There has been proposed a method for producing a crystalline polymer sheet, which is drawn through at least a draw ratio of 2.5 times or more through a pair of heated rollers (see, for example, Patent Document 1).
JP 60-15120 A

  However, in order to draw and stretch a polyester resin by the method for producing a crystalline polymer sheet, the polyester resin is too hard at low temperatures and cuts due to lack of flexibility necessary for stretching, and is not oriented at high temperatures. Since relaxation becomes dominant, it has been difficult to obtain a stretched polyester resin sheet excellent in tensile strength, tensile elastic modulus, heat resistance and the like.

  Polyester resin is a hard resin, and has a high elastic modulus even when heated to an appropriate temperature and pulled out, making it difficult to pull out, especially when a wide polyester resin sheet is pulled out. The polyester resin sheet which became thick and uniform thickness, in other words, uniformly stretched, was not obtained.

  An object of the present invention is to provide a method capable of easily and stably producing a stretched thermoplastic polyester resin sheet having excellent tensile strength, tensile elastic modulus, heat resistance and the like by drawing and drawing in view of the above-mentioned drawbacks. There is to do.

The method for producing a stretched thermoplastic polyester resin sheet of the present invention is obtained by converting an amorphous thermoplastic polyester resin sheet from “the glass transition temperature of the thermoplastic polyester resin −20 ° C.” to “the thermoplastic polyester resin. In a method for producing a stretched thermoplastic polyester resin sheet that is heated to a temperature of “glass transition temperature of + 20 ° C.”, drawn at a constant speed through a pair of rolls , and further uniaxially stretched at a temperature higher than the draw stretching temperature. The surface of the roll is a smooth metal roll or a tetrafluoroethylene resin-coated roll.

  Examples of the thermoplastic polyester resin include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyglycolic acid, poly (L-lactic acid), poly (3-hydroxybutyrate), and poly (3-hydroxybutyrate). / Hydroxyvalerate), poly (ε-caprolactone), polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polybutylene succinate / lactic acid, polybutylene succinate / carbonate, polybutylene succinate / terephthalate, poly Examples include butylene adipate / terephthalate, polytetramethylenadipate / terephthalate, and polybutylene succinate / adipate / terephthalate. Terephthalate is preferable.

  If the intrinsic viscosity of the thermoplastic polyester-based resin is too low, drawdown is likely to occur at the time of forming the sheet, and if it is too high, the mechanical strength (particularly the elastic modulus) does not increase even when stretched. 0 is preferred.

  The thickness (d) of the thermoplastic polyester resin sheet is not particularly limited, but if it is less than 0.5 mm, the sheet thickness after stretching becomes too thin, and the strength during handling may not be sufficiently large. If it exceeds 1, it may be difficult to stretch, so 0.5 to 5 mm is preferable, and 0.9 to 4 mm is more preferable.

  The thermoplastic polyester resin sheet is in an amorphous state. The thermoplastic polyester resin sheet may be in an amorphous state, and the crystallinity thereof is not particularly limited, but the crystallinity measured by a differential scanning calorimeter is preferably less than 10%, more preferably. Is less than 5%.

  In the present invention, the thermoplastic polyester resin sheet in the amorphous state is drawn and stretched at a constant speed through a pair of rolls. First, the state of the thermoplastic polyester resin sheet when drawing and stretching will be described with reference to the drawings.

  FIG. 1 is an explanatory view showing a state in which a thermoplastic polyester resin sheet is drawn and stretched between rolls. In the figure, reference numerals 1 and 1 denote a pair of rolls installed with a distance between rolls (D), and a broken line indicates the center position of the rolls 1 and 1.

  The thermoplastic polyester resin sheet 2 having a thickness (d) is tensioned in the direction of the arrow and is drawn and stretched at a constant speed. The thermoplastic polyester resin sheet 2 comes into contact with the roll 1 at the position of point a and is compressed by the rolls 1 and 1 while being pulled out.

  The thermoplastic polyester resin sheet 2 is drawn at a constant speed, that is, the thermoplastic polyester resin sheet 2 is tensioned in the direction of the arrow, so that it is slightly upstream from the clearance point b of the rolls 1 and 1. It is peeled from the rolls 1 and 1 at a point c and pulled out at a constant speed.

  Therefore, the thermoplastic polyester resin sheet 2 is compressed and oriented by the rolls 1 and 1 between the point a and the point c, and is stretched by the tension due to drawing downstream from the point c. In order to obtain a stretched thermoplastic polyester resin sheet having excellent tensile strength, tensile elastic modulus, heat resistance, etc., the longer the distance from the point a to the point c that is compression-oriented, the better. When it becomes higher, the point c where the thermoplastic polyester resin sheet is peeled moves to the upstream side, and the distance from the point a to the point c becomes shorter. Therefore, the rolls 1 and 1 preferably have a low friction coefficient. A metal roll or a tetrafluoroethylene resin-coated roll having a smooth surface is used.

  If the temperature of the pair of rolls is low, the thermoplastic polyester resin sheet is too hard and may be cut first even if it is to be pulled out. On the contrary, when the temperature becomes high, the thermoplastic polyester resin sheet becomes soft and the sheet is cut by the tension that pulls out the sheet, so that “the glass transition temperature of the thermoplastic polyester resin −20 ° C.” To a temperature of “the glass transition temperature of the thermoplastic polyester resin + 20 ° C.”.

  Further, the distance between rolls (D) of a pair of rolls must be reduced in proportion to the thickness (d) of the thermoplastic polyester resin sheet in order to increase the draw ratio, but the ratio is too small. The sheet is cut by the tension that pulls out the sheet, and when it becomes larger, the draw ratio becomes smaller, the orientation of the thermoplastic polyester resin by stretching decreases, and physical properties such as tensile strength, tensile elastic modulus, heat resistance, etc. do not improve. The ratio of the distance between the pair of rolls (D) and the thickness (d) of the thermoplastic polyester resin sheet (the distance between the pair of rolls (D) / the thickness of the thermoplastic polyester resin sheet (d)) Is preferably 0.2 to 0.8.

  In the present invention, the amorphous polyester resin sheet in an amorphous state is drawn and stretched at a constant speed through a pair of rolls, so that the thermoplastic polyester resin sheet is constant by applying tension to the thermoplastic polyester resin sheet from the downstream side of the pair of rolls. Pull out at speed. If the drawing speed of the thermoplastic polyester resin sheet is slow, the draw ratio becomes small, the orientation of the thermoplastic polyester resin due to drawing decreases, and physical properties such as tensile strength, tensile elastic modulus, heat resistance, etc. do not improve, and it is too fast. Since the stretched thermoplastic polyester resin sheet may be cut, it is preferably 1 to 10 m / min, more preferably 4 to 9 m / min.

  The draw ratio of the above-described drawing stretching is not particularly limited. However, if the stretching ratio is low, a sheet excellent in tensile strength and tensile elastic modulus cannot be obtained. If the stretching ratio is high, the sheet tends to break during stretching. 1.2-8 times, more preferably 2-6 times.

  In order to improve physical properties such as tensile strength, tensile elastic modulus, heat resistance, etc., it is preferable to orient the thermoplastic polyester resin more uniformly, so that not only the pair of rolls are drawn but also the drawn heat The plastic polyester resin sheet is stretched while being heated. Therefore, the drawing speed is adjusted so that the draw ratio of the stretched thermoplastic polyester resin sheet is larger than the distance between the pair of rolls (D) / the thickness of the thermoplastic polyester resin sheet (d). It is preferable that the resin sheet is drawn within the range of the drawing speed.

  Further, when the amorphous polyester resin sheet in the amorphous state is pulled out, the roll does not need to be rotated. However, especially when the thickness of the thermoplastic polyester resin sheet is thick, the heat storage of the roll by shearing heat generation is required. It is preferable to rotate the sheet in the drawing direction because the temperature of the resulting sheet is likely to increase.

  When the rotation speed of the roll is slow, the contact time between the roll and the thermoplastic polyester resin sheet becomes longer, frictional heat is generated, the roll temperature rises, and the effect of cooling the heated thermoplastic polyester resin is reduced. However, when the predetermined drawing and stretching temperature is exceeded and the rotational speed of the roll is increased, only the thermoplastic polyester resin on the surface of the thermoplastic polyester resin sheet flows and cannot be drawn and drawn uniformly. Further, the elastic modulus of the drawn and drawn thermoplastic polyester resin sheet is lowered.

  Therefore, the rotational speed of the roll is preferably substantially the same or lower than the pulling speed when the thermoplastic polyester resin sheet is pulled at a pulling speed under the same conditions while the roll is not rotating.

  Further, when the thickness of the thermoplastic polyester resin sheet is large (1.5 mm or more), heat generated by shearing between the roll and the sheet is increased, and therefore the rotation speed of the roll is preferably 50 to 100% of the above drawing speed. . Moreover, when the thickness of the thermoplastic polyester resin sheet is thin, the cooling effect by the roll is great, so the rotation speed of the roll may be slow.

In order to improve physical properties such as tensile strength, tensile modulus, heat resistance, etc., the drawn and stretched thermoplastic polyester resin sheet is uniaxially stretched at a temperature higher than the temperature of the drawing and stretching .

  The polyester resin of the thermoplastic polyester resin sheet that has been drawn and stretched is highly oriented because molecular chains are highly oriented in a state in which isotropic crystallization and orientation due to heat, which is an impediment to stretching, are suppressed. Although the elastic modulus is excellent, the degree of crystallinity is low, so that when heated, the orientation is easily relaxed and the elastic modulus is lowered.

  However, the uniaxial stretching of the drawn and drawn thermoplastic polyester resin sheet at a temperature higher than the drawing and drawing temperature increases the degree of crystallinity without relaxation, and the orientation is easy even when heated. Thus, a stretched thermoplastic polyester resin sheet having excellent heat resistance that is not relaxed by the heat treatment can be obtained.

  As the uniaxial stretching method, a roll stretching method is preferably used. The roll stretching method is a method in which a stretched raw fabric is sandwiched between two pairs of rolls having different speeds, and the stretched raw fabric is pulled while being heated, and the molecular orientation can be strongly oriented only in a uniaxial direction.

  The temperature during the uniaxial stretching may be higher than the drawing stretching temperature, but if it is too high, the primary stretched thermoplastic polyester resin sheet is melted and cut. A temperature range from the rising temperature of the crystallization peak of the thermoplastic polyester resin to the rising temperature of the melting peak in the differential scanning calorimetry curve measured in min is preferable.

  The rising temperature of the crystallization peak of polyethylene terephthalate is about 120 ° C., and the rising temperature of the melting peak is about 230 ° C. Accordingly, when the polyethylene terephthalate sheet is uniaxially stretched, it is preferably uniaxially stretched at about 120 ° C to about 230 ° C.

  The stretching ratio of the uniaxial stretching is not particularly limited. However, if the stretching ratio is low, an excellent sheet such as tensile strength and tensile elastic modulus cannot be obtained. If the stretching ratio is high, the sheet tends to break during stretching. Therefore, 1.05-3 times are preferable, More preferably, it is 1.1-2 times.

  The total draw ratio of drawing and uniaxial drawing is preferably 2 to 24 times, more preferably 3 to 16 times, and even more preferably, because the absolute value of the linear expansion coefficient becomes large if it is too small or too large. Is 4 to 12 times.

The structure of the production method of the stretched thermoplastic polyester resin sheet of the present invention is as described above, and is drawn by using a roll having a low friction coefficient , and further uniaxially stretched at a temperature higher than the draw stretching temperature . A stretched thermoplastic polyester resin sheet having excellent tensile strength, tensile modulus, heat resistance and the like can be easily and stably produced. In addition, since the obtained stretched thermoplastic polyester resin sheet has a small absolute value of the linear expansion coefficient, the expansion and contraction due to temperature change is small, light weight, and excellent in impact resistance, durability, workability, etc. It can be suitably used as an exterior building material such as a bag.

  Next, although an example of the present invention is given and explained in detail, the present invention is not limited to the following example.

Example 1
Thickness (d) of 2.0 mm obtained by melt-extrusion of polyethylene terephthalate (manufactured by Unitika Ltd., trade name “NEH-2070”, intrinsic viscosity 0.88, glass transition temperature 76.7 ° C.) and rapid cooling A polyethylene terephthalate sheet (1.3% crystallinity) is supplied to a stretching device (manufactured by Kyowa Engineering Co., Ltd.), preheated to 80 ° C, and then heated to 74 ° C for a pair of smooth surfaces with a tetrafluoroethylene resin coating A roll (roll interval: 0.6 mm) was drawn at a speed of 5 m / min and drawn and drawn to obtain a drawn and stretched polyethylene terephthalate sheet having a draw ratio of about 4 times.

It was -0.3 * 10 < ^-5 > (/ degreeC) when the linear expansion coefficient was measured based on JISK7197 using the obtained drawing extending | stretching polyethylene terephthalate sheet | seat. The linear expansion coefficient was measured by increasing the temperature from −20 ° C. to 100 ° C. at 5 ° C./min, further decreasing the temperature from −20 ° C. at 5 ° C./min, and obtaining the temperature from 0 ° C. to 60 ° C. Moreover, it was 8.1 GPa when the tensile elasticity modulus was measured at 23 degreeC and 50% RH based on the tension test method of JISK7113.

It is explanatory drawing which shows the state by which the thermoplastic polyester-type resin sheet is draw-drawn between rolls.

Explanation of symbols

1 roll 2 thermoplastic polyester resin sheet

Claims (5)

The amorphous polyester resin sheet in an amorphous state is heated to a temperature of “glass transition temperature of the thermoplastic polyester resin −20 ° C.” to “glass transition temperature of the thermoplastic polyester resin + 20 ° C.” A method for producing a stretched thermoplastic polyester resin sheet that is drawn and stretched at a constant speed through a pair of rolls , and further uniaxially stretched at a temperature higher than the draw stretching temperature , wherein the roll has a smooth metal roll or tetrafluoro A method for producing a stretched thermoplastic polyester resin sheet, which is an ethylene resin-coated roll.  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 thermoplastic polyester resin sheet has a thickness of 0.5 to 5.0 mm.  The method for producing a stretched thermoplastic polyester resin sheet according to any one of claims 1 to 3, wherein a drawing speed of the stretched thermoplastic polyester resin sheet is 1 to 10 m / min. The amorphous polyester resin sheet in an amorphous state is preheated at a temperature of “the glass transition temperature of the thermoplastic polyester resin—20 ° C.” to “the glass transition temperature of the thermoplastic polyester resin + 10 ° C.” and then drawn. The method for producing a stretched thermoplastic polyester resin sheet according to any one of claims 1 to 4 , wherein the stretched thermoplastic polyester resin sheet is stretched.

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