JPS63153115A - Polyethylene terephthalate oriented body - Google Patents

Abstract

PURPOSE:To obtain an oriented body having high elastic modulus and excellent dimensional stability, by setting the degree of crystallinity, the crystalline size and the orientation factor of crystalline to specified values respectively. CONSTITUTION:The degree of crystallinity, the crystalline sizes in the direction of crystalline faces 105 and 100 and the orientation factor of crystalline of a polyethylene terephthalate oriented body are set to be 70-92%, 80-100Angstrom and 40-60Angstrom , and 0.96-1.0, respectively. If the degree of crystallinity becomes larger than 92%, the oriented body comes to have more rigid property and the impact resistance is lowered. On the other hand, if it becomes smaller than 70%, shrinkage and abnormal deformation occur when exposed to a high temp. above Tg and the dimensional stability becomes worse. If the crystalline sizes in the direction of crystalline faces 105 and 110 become outside of the above described ranges, the elastic modulus decreases and both the dimensional stability and the impact resistance decrease, too.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an oriented polyethylene terephthalate body having a high elastic modulus. In more detail, when used as a base material of a magnetic recording medium and a flexible circuit board, the elastic modulus,
The present invention relates to an oriented polyethylene terephthalate body exhibiting extremely high dimensional stability.

[Prior Art] In the conventional polymer film or molding industry, only oriented bodies having an elastic modulus significantly lower than the crystalline elastic modulus of the polymer have been produced.

For example, the tensile modulus in the main orientation direction of a commercially available polyethylene terephthalate (hereinafter abbreviated as PET) film uniaxially stretched at a high magnification is 8 GPa, which corresponds to only 7°4% of the crystal elastic modulus of 108 GPa. . This is mainly because the molecules are not highly elongated and the inherent properties of the molecules are not reflected in the bulk properties. In other words, if the molecular chain is folded or twisted, it will hardly perform the function of transmitting force. For this reason, several attempts have been made to extend the molecular chain to a high degree. For example, J, Appl, Pol
ymer Sci, 26.213 (1981).

J, Macromol, Sci, -phys, 2
6.213 (1981), J: Palym, Sc.
i, Polym, Phys, Edn, , 21.11
33.1147 (1983), Palmer, 27
゜1559 (1986), etc.

[While the invention is trying to solve the problem] However, a film in which the degree of molecular orientation is increased by the method described above,
Alternatively, although the molded body exhibits a high modulus of elasticity to some extent, when the oriented body is exposed to a temperature higher than the glass transition point (Tg) of PET, the dimensions change significantly, which often limits its use. The present invention aims to provide a PET oriented body having a high elastic modulus and excellent dimensional stability.

[Means for Solving the Problems] The present invention has a crystallinity of 70 to 92% and a crystal size of 80 to 10% in the crystal planes (105> and (100) directions, respectively).
0 Å, 40 to 60 people, and crystal orientation coefficient of 0.96 to
The main feature of this invention is a PET oriented body characterized by a 1.0.

The crystallinity of the PET oriented body of the present invention is 70 to 92%.

It is preferably within the range of 80 to 88%. This crystallinity is a parameter indicating the degree to which PET crystals exist inside the oriented body. When this value is larger than the above range, the oriented body becomes more rigid, has lower impact resistance, and becomes extremely brittle. On the other hand, if it is smaller than the above range, shrinkage or abnormal deformation occurs when exposed to high temperatures above Tg, resulting in poor dimensional stability.

Next, the crystal plane (105) and (
The crystal size in the 100) direction is 80 to 100 Å, respectively.
, 40-60 Å, preferably 80-100 Å, 45-5
It is necessary to be within the range of the five major factors. The size in the (105) direction is related to how well the molecules are oriented. When a well-elongated PET molecular chain is crystallized (10
5) The size of the direction increases. One of the characteristics of the oriented body of the present invention is that although the size in the (105) direction is quite large, the (
100) is relatively small, with 40 to 60 people. If the size in the (105) direction is larger than 100, the oriented body will easily tear in the orientation direction, resulting in poor impact resistance. On the other hand, if it is less than 80, the elastic modulus will be as low as that of a normal molded product, and the high elastic modulus, which is one of the goals of the present invention, cannot be achieved.

On the other hand, if the size in the (100) direction is smaller than the above range, the oriented body will have poor dimensional stability, and if the size in the (100) direction is larger than the above range, it will become brittle and have reduced impact resistance.

Next, the crystal orientation coefficient of the oriented body of the present invention is 0.96 to 1. O
1 preferably within the range of 0.98 to 0.99. When the crystal orientation coefficient is smaller than the above range, the elastic modulus of the oriented body is usually as low as that of a molded article or film. Furthermore, if it is larger than the above range, it cannot exist according to the definition of the crystal orientation coefficient, so it is excluded from the scope.

Note that the PET constituting the oriented body of the present invention has an intrinsic viscosity (2
(measured in ortho-chlorophenol at 5°C) is 0.5
It is preferably within the range of 8 to 1.50. Outside this range, orientation processing tends to be difficult and mechanical strength tends to be somewhat inferior.

The method for producing the oriented body of the present invention is not particularly limited, and any method may be used. For reference, one example is as follows.

First, the PET material suitable for producing the film of the present invention is prepared by adding insoluble fine particles to the system during the polycondensation reaction, and then forming one or more types of alkali metals or alkaline earth metals during the polycondensation reaction. It is manufactured by precipitating particles (so-called precipitated particles) that are part of the components. To be more specific, when producing polyester by transesterifying or esterifying terephthalic acid or its ester-forming derivative with ethylene glycol, and subsequently carrying out a polycondensation reaction, optional At this point, fine particulate matter insoluble in the system (specific surface area 5 m
2/Cl or more is preferable), and particles containing one or more alkali metals or alkaline earth metals as part of the constituent components are precipitated during the polycondensation reaction.

The PET raw material made in this way is sufficiently vacuum-dried in a conventional manner, then fed to an extruder for melt extrusion, the molten polymer is filtered, formed into a sheet or rod shape with a die, and then rapidly cooled. By solidifying, an unoriented body is created. The degree of crystallinity of this unoriented body is preferably 4% or less. If the degree of crystallinity is higher than that, it may be difficult to achieve high-magnification molecular orientation. Both ends of this unoriented sheet or rod are held with clips, and a stretching machine with an oven is used to
Stretching temperature 20-100°C1, preferably 20-60°C
4.0 or more, more preferably 4.2 to 5.0 in one axis at °C
Stretch it twice. By setting the magnification to 4 times or more, it becomes easy to develop a high elastic modulus. On the other hand, when it is 5 times or less, it has the advantage that it is difficult to break during stretching. After the stretched product is left to cool, it is taken out of the oven and re-stretched at room temperature by 1 to 1.5 times, more preferably 1.25 to 1.5 times. After stretching, the sample is fixed under tension to a fixing frame made of steel, for example, using a metal jig to prevent shrinkage. If the re-stretching ratio is less than 1.0, this corresponds to the stretched sample being loosened and attached to the fixed frame, and this state is not preferable for obtaining a material with a high elastic modulus. Moreover, if it exceeds 1.5 times, the sample tends to break during re-stretching, which is not preferable.

The sample attached to the fixed frame was kept at a temperature of 230°C, near the melting point of PET.
The heat treatment is preferably performed at ~290°C, more preferably at 240-260°C for 2 hours or more. Heat treatment temperature is 230℃
If it is less than this, a long heat treatment time is required to adjust the structural parameters referred to in the present invention, which is not preferable. Also,
If the heat treatment temperature exceeds 290'C, even if the pretreatment described below is carried out, some of the crystals will melt, the elongated molecular chains will be loosened, and the orientation will be relaxed, resulting in unfavorable properties.

The heat treatment is preferably carried out in a dry nitrogen stream in order to prevent thermal deterioration and hydrolysis of the polymer. 250°
In the heat treatment at 250'C or higher, it is preferable to perform a preheat treatment at 250'C in advance to prevent the crystals in the sample from melting and the molecular orientation to be relaxed. When the crystal melting point increases to 270'C or higher by this treatment, a full-scale heat treatment is performed below 270'C.

If heat treatment is performed at 270'C or higher,
'C pretreated to raise the melting point to 270℃ or higher,
It is preferable to perform pretreatment again at 260'C to raise the crystal melting point to 290'C or higher, and then carry out full-scale heat treatment at 270'C or higher. In this way, high-temperature heat treatment is performed, which is characterized by raising the heat treatment temperature to a high temperature while increasing the crystal melting point of the PET array body in the pretreatment.

In the manner described above, the PET oriented body of the present invention can be obtained.

[Effects of the Invention] The present invention is based on the discovery that an oriented body with a high elastic modulus and excellent dimensional stability can be obtained by setting the crystallinity, crystal size, and crystal orientation coefficient to specific values. A non-quality molded product is stretched at a high magnification to create an oriented structure in which the molecular chains are sufficiently elongated and aligned, and then the molecular chains are crystallized at high temperatures while minimizing shrinkage. .

In such a state, the crystals grow large along the molecular chains, which is advantageous for improving the elastic modulus. Furthermore, although the molecular chains in the amorphous region may loosen with crystallization, by further promoting crystallization, the winding effect of the amorphous region due to crystal growth is taken care of, and the amorphous region is stretched to a certain extent. A state of local thermodynamic equilibrium is reached at the state. In such a state, the contractile force of the elongated amorphous portion is small and the crystallinity is relatively high, so that a structure with very good dimensional stability is considered to be substantially formed. It is also believed that the high degree of crystallinity, the crystals growing largely in the direction of the molecular chains, and the fact that they are well aligned in the orientation direction, make the elastic modulus significantly higher than that of conventional films, sheets, and rod-shaped processed products.

The oriented polyethylene terephthalate body of the present invention has a high elastic modulus, low heat shrinkage, and excellent dimensional stability. Therefore, this oriented body can be used, for example, in a magnetic recording medium (
It is useful for the production of substrates for tape discs, video discs, etc.) and flexible printed circuit boards. Further, this oriented body can be cut into short stable pieces and dispersed in various plastic materials and inorganic materials to be used as a reinforcing filler.

[Method for Measuring Structure/Properties] (1) Crystallinity Measure the density according to ASTM D1505 and calculate the crystallinity. When calculating the degree of crystallinity, the density of the crystalline part and the amorphous part of PET are each 1°455 CJ10+
f, 1.335Q/cy+t.

(2) Crystal size When diffraction peaks are observed using a transmission method using an X-ray diffractometer while changing the direction perpendicular to the stretching (orientation) direction of the oriented body and the incident angle of X-rays, the diffraction peak is approximately 13°. from PET
The crystal size D (person) in the (100) plane direction is calculated as follows.

D=λ/ (B-b)CO3θ (1) However, B
: half width of diffraction peak, b=0.12, λ: α for Cu
Line wavelength (1,541,8 people), θ: peak diffraction angle.

In addition, the size in the (105) plane direction is determined by the diffraction peak observed at approximately 21.5° using the transmission method while changing the stretching (orientation) direction of the oriented body and the incident angle of X-rays, and from this peak, equation (1) Calculate.

(3) Crystal orientation coefficient The crystal orientation coefficient fc was evaluated by X-ray diffraction method. fC is given by the following equation.

fc=(3<C082φ.z>-1)/2where<CO32φ. , 7〉 is the root mean square value of the cosine of the angle C1z between the C-axis and the orientation axis of the crystal, which is the Wilckin
sky method (J, ADI)1. Phys,, 30
Vol. 7, No. 2 (1959)), it is given by the following equation.

<C082φ. ,z)=1-0.3481<CO3
2φ >-0,773 100, Z 3<CO32φTIO,z 〉- 〇, 8786<CO32φ 010, Z > where <CO32φ >, <CO32φT10゜i
oo, z7>, <CO32φ> are (10010
, Z O), (110), and (010) planes in the azimuth direction.

(4) Elastic modulus The elastic modulus was measured at a frequency of 110 Hz and a temperature of 25° C. using a dynamic viscoelasticity measuring device (“Rheopybron” manufactured by Toyo Baldwin Co., Ltd.).

(5) Dimensional stability (thermal shrinkage rate) A sheet is cut into a length of 1Qmm in width and 250mm in length in the longitudinal direction of the orientation axis, and a rod-shaped object is cut into a length of 25Qmm. Two gauge lines were placed at 200 mm intervals, and the distance was accurately measured (this was measured in Amm).
). The sample was left in a hot air oven at 180° C. for 10 minutes with a load of 3° OC+ applied to the tip of the sample, and then the sample was cooled to room temperature and the distance between the gauge lines was measured (this is defined as 3 mm).

(A-B/A)X 106 was determined, and this was taken as the heat shrinkage rate.

A thermal shrinkage rate of 1% or less was considered good dimensional stability, and a thermal shrinkage rate of 1% or more was considered poor.

(6) Impact resistance Charby impact strength (unit: 1 cm/mm
) was measured. In addition, the value is 2 for the orientation direction of the sheet or rod.
It was calculated for the case where it was set horizontally between the fulcrums. When the Charvi impact strength was 20 or more, it was determined that the impact resistance was good, and when it was less than 20, it was determined that the impact resistance was poor.

[Examples] The present invention will be explained using the following Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 1 part by weight of dimethyl terephthalate, 69 parts by weight of ethylene glycol, 0.8 parts by weight of diethylene glycol,
Using 0.09 parts by weight of calcium acetate as a catalyst, the transesterification reaction was carried out by a conventional method, and the resulting product contained 0.03 parts by weight of antimony trioxide, 0.3 parts by weight of lithium acetate, and 0.2 parts by weight of trimethyl phosphate. parts by weight and silicon dioxide fine powder (specific surface area: 180 TI+2/Cl) were added and polymerized by a conventional method to obtain a polymer pellet with an intrinsic viscosity of 0.62. After vacuum drying this pellet at 180'C for 110 hours, it was extruded. The molten sheet is then melted and extruded at 282°C, passed through a gear pump and a filter, and then discharged in the form of a sheet from a T-type nozzle.The molten sheet is heated to a surface temperature of 40'
It was wound around a cooling drum of C and cooled and solidified to produce an unstretched sheet.

During this cooling, in order to improve the adhesion between the molten sheet and the drum surface, a wire electrode is placed on the molten sheet side, and a DC voltage of 8KV is applied to it to ensure that the molten sheet is well adhered to the drum. did.

This unstretched sheet (thickness: 300 μm) was made into a width of 2 Q mm.

It was cut into short pieces with a length of 1 oomm and tested at room temperature (approximately 20°C) at a tensile speed of 10 mm 1 n- using a tensile testing machine (“Ten5ilOn” manufactured by Toyo Baldwin Co., Ltd.).
Cold stretch at 1k. Since stretching involves necking, the stretching ratio was increased until the entire sample was stretched uniformly.

After stretching, when the sample is separated from the chuck of the tensile tester,
The sample length will spring back and become somewhat smaller. Estimating the stretching ratio from the sample length after springback, it is approximately 4.2.
It was double that. This stretched sample was tested again with a tensile tester of 1.2
The sample was stretched 5 times and both ends of the sample were fixed to a steel frame using a jig. This was heat-treated at 250°C for 24 hours in a nitrogen gas circulating hot air oven, and then at 260°C for 3 hours.
Heat treatment was performed for 60 hours.

The properties of the uniaxially stretched film obtained in this way are that the intrinsic viscosity of the film is 0.63 dff/Q, the crystallinity is 90%, and (1
The crystal sizes in the 05) plane and (100) plane directions are 96 Å and 56 Å, respectively, and the crystal orientation coefficient is 0.99. Elastic modulus 35
．． Ivy at 4GPa.

Furthermore, when the impact resistance and one-dimensional stability of the film were evaluated, all were found to be good.

By variously changing the heat treatment temperature, heat treatment time, and re-stretching ratio under the conditions of Example 1, samples with different values of crystallinity, crystal size, and crystal orientation coefficient were prepared. Table 1 shows the results of evaluating the elastic modulus, dimensional stability, and impact resistance of these films. These results show that a film having characteristic values within the range of the present invention has a high elastic modulus and is excellent in dimensional stability and impact resistance.

Note that the re-stretching ratio refers to the stretching ratio at which a cold-stretched film is re-stretched and fixed to a metal frame.

Claims (1)

[Claims] Crystallinity 70-92%, crystal planes (@1@05) and (
The crystal size in the 100) direction is 80 to 100 Å, respectively.
40-60 Å, crystal orientation coefficient 0.96-1.0
An oriented polyethylene terephthalate body characterized by: