JPS6090746A - Polyester thin cylindrical molding - Google Patents

Abstract

PURPOSE:To obtain a polyester thin cylindrical molding of an optimum thickness as a carrier for high-density magnetic recording elements, which is excellent in physical properties and adhesion with regenerating head, by specifically designating the intrinsic viscosity of polyester, thickness, surface roughness and degree of orientation of polyester. CONSTITUTION:For polyester thin cylindrical moldings having main repeating unit of ethylene terephthalate, the intrinsic viscosity is designated to 0.5 or more for maintaining of mechanical strength and preventing vertical tear, the thickness is designated to 100mum or less from standpoint of adhesion with head for recording regeneration, and the difference between maximum thickness and minimum thickness of cross section of the molding in parallel with axis is designated to 30mum or less for preventing longitudinal tear. The surface roughness in the circumferential direction of the periphery of the molding is designated to 0.05mum or less from the standpoint of longitudinal tear prevention, and orientation degrees in axial and circumferential directions are designated to 0.03 or more from the standpoint of longitudinal tear resistance and circumferential strength. The cylindrical molding is obtained by a vacuum molding method to push a heated film 5 into the cavity 2 by a plug 1 or a blow molding method.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a molded body that can be used as a recording element carrier used in the electronic device industry, and furthermore, a molded body that can be equipped with a high-density atomized sickle element or the like on its inner and/or outer surface. The present invention relates to a polyester cylindrical molded body having smooth surface properties, thin walls, and uniform wall thickness distribution.

[Conventional technology]

Conventionally, thin cylindrical molded products made of polyester have been supplied with tubular preforms obtained by the so-called inflation molding method, such as Seiban No. 1i838-18978, or by extrusion molding, such as in Japanese Patent Publication No. 46-32080. A molded article obtained by stretching and expanding between a pulley and a pulley puller is known. However, since the molded product obtained by this manufacturing method is in a flat folded state, there are defects such as crease marks and vertical streaks (die streaks) that occur when extruded from a die. When using the core as a carrier for a recording element, the nuclear defect portion becomes a serious drawback in use, and therefore improvements are desired. [Object of the invention] The present invention was made against the background of the above circumstances,
Its purpose is to have a cylindrical shape with thin walls, no defects such as creases and die lines, excellent surface smoothness and uniform thickness distribution, and a polyester material with excellent strength and heat-resistant dimensional stability. There is a need to provide a molded body. [Structure of the Invention] The present inventor has focused on such problems, and as a result of intensive research into a thin cylindrical molded product without defects such as Maeki, the inventor has found that a molded product made of a specific polyester with a specific shape, wall thickness, degree of orientation, and It was discovered that the defects could be improved if the molded article had surface properties, and the pressure of the present invention was achieved.6. That is, the present invention provides a cylindrical molded body made of polyester whose main repeating unit is ethylene terephthalate and whose intrinsic viscosity is 0.5 or more, and whose wall thickness is 10
0 μ or less, the difference between the maximum wall thickness and minimum wall thickness of the cross section of the molded body parallel to the axis is 30 μ or less, and the circumferential surface roughness CCLA (unit: #) of the inner and/or outer surface of the molded body is 0. 05 or less, and the degree of orientation in the axial direction and the circumferential direction is each 0.0.
It is a thin cylindrical molded article made of polyester having a thickness of 3 or more. The polyester in the present invention is mainly a homopolymer of polyethylene terephthalate (hereinafter abbreviated as PET), and a part of the terephthalic acid component may be, for example, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid (1') phenoxyethane dicarboxylic acid, Aromatic dicarboxylic acids such as diphenyl ether dicarboxylic acid, diphenylsulfone dicarboxylic acid, etc.; alicyclic dicarboxylic acids such as hexahytrotyrentalic acid, hexahyto-isophthalic acid, etc.; aliphatic dicarboxylic acids such as adipic acid, sepatic acid, azelaic acid, etc. , p-β-human p-oxyethoxybenzoic acid, ε-oxycaproic acid, etc., and/or a portion of the ethylene glycol component, such as Methylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol 9 neopentylene glycol, diethylene glycol, l,1-cyclohexane dimethylol, l,4-cyclohexane dimethylol,
Polyfunctional compounds of other glycols and functional derivatives thereof such as 2,2-bis(4'-β-hyFpxyethoxyphenyl)propane, bis(4'-β-hyFpxyethoxyphenyl)sulfonic acid Replace with 181 or more and 2 w
A copolymer copolymerized in a range of t or less may also be used. The intrinsic viscosity (hereinafter referred to as IV) of the polyester molded article of the present invention is 0.5 or more, more preferably 0.6 or more, particularly KO07 or more. (2) If v is lower than O or S, mechanical strength and vertical tearing will be significant and it will be difficult to withstand use. IV
When mK is 0.6 or more and mK0.7 or more, the mechanical strength is good. The thickness of the molded body of the present invention is 100μ or less, but 100μ
If it is thicker than this, for example, when the present invention is used as a recording element carrier, defects such as poor adhesion with a recording/reproducing head will occur. The preferred range of wall thickness is 30μ to 80μ
, especially in the range of 40 to 60μ, the adhesion with the reproduction head,
This is preferable in terms of operational rigidity, etc. There is no particular lower limit to the wall thickness, but if the wall thickness is too thin, the rigidity will be weakened and it will be difficult to manufacture a molded product. The thickness of the molded body of the present invention is determined by the weight reduction and
In order to reduce the size, it is thinner than the conventional cylindrical molded body, which is less than 100 μm thick.
In the case of such a thin wall, longitudinal cracking from the cut plane parallel to the axis of the molded body becomes significant, which poses a very serious problem. Regarding the longitudinal cracks, the difference between the maximum wall thickness and the minimum wall thickness of the cross section of the compact parallel to the axis should be 30μ or less, and the inner surface and / The height of the stripe and/or striped convex portion should be 2 or less, and the degree of orientation in the axial direction and circumferential direction should be 0.
．． It is extremely effective to set the value to 03 or higher. If the degree of orientation in the axial direction is less than 0.03, the strength in the circumferential direction of the molded body is insufficient.
A value of 0.05 or more is preferable because the single alignment longitudinal tear strength becomes good. Furthermore, the ρ degree in the axial direction and the circumferential direction is 0.03.
If it is smaller than , the strength will be significantly reduced when heat treatment is performed to further improve the heat-resistant dimensional stability of the skeleton molded body. In the present invention, the degree of orientation in the axial direction refers to the difference in refractive index between the axial direction and the thickness direction, and the degree of orientation in the circumferential direction refers to the difference in refractive index between the circumferential direction and the thickness direction. The surface roughness in the circumferential direction of the inner and/or outer surface of the molded article of the present invention (center edge average roughness (abbreviated as CLA)) is 0.05 or less, but recording is not possible when CLA is greater than 0.05. This is not preferable because the performance when doing so is degraded. The shape of the molded body of the present invention is substantially cylindrical, and the values of the outside diameter (D) and the length H) of the molded body vary depending on the application, but the molded body is used as a carrier for a recording element. When used, those within the range of the following formula are usually useful. 10w≦D≦80m 20m≦H≦200u H/D≧2 Furthermore, if the shape is pressed into a shape such as a part of a cone whose cylindrical side part has an angle of 0.1 part or more with respect to the central axis, it will overlap when handling the molded body. It is preferable because it can be matched, and it is less likely to be damaged by contact with molding equipment such as a mold when molding a molded product, so it has excellent appearance, surface smoothness, and longitudinal tear strength. Density C of the molded article of the present invention, usually t, a 611/cd
As mentioned above, in order to further improve the heat-resistant dimensional stability of the molded product, when heat treatment is performed while restraining the molded product to maintain its cylindrical shape, the density is preferably 1.37#/2- or more. A good condition is that the density is 1.381/csA or more. It is preferable to perform such a heat treatment because the roundness of the molded article is further improved. The molded article of the present invention can be produced by thermoforming a substantially unstretched amorphous sheet using a cylindrical plug mold and/or a cavity mold having cylindrical side surfaces, as shown in FIG. 1, for example. Alternatively, as shown in FIG. 7, a substantially amorphous PET tube is stretched in the axial direction within a temperature range that allows stretching, and then expanded by blowing in the circumferential direction to form a thin cylinder made of biaxially oriented L2PET. It can be obtained by a method of molding a shaped body. In FIG. 1, 1 is a plug, 2 is a cavity, 3 is a heater, 4 is a clamp, and 5 is a polyester film for thermoforming. During thermoforming, the polyester film 5 is held by the clamp 4. , see figure (a) where it is heated to the drawing temperature with the heater 3. Next, the heater 3 is moved from above the film 5, and the plug 1 is pressed from above the film 5 into the cavity 2, thereby forming the film 5 into a cylindrical preform 6 with a bottom (see figure (b)). plug l
, the cavity 2 is heated, and the preform 6 is molded into the cavity 2 by simultaneously blowing compressed air from the plug 1 (air pressure forming), by reducing the pressure in the cavity 2 (vacuum forming), or by performing both at the same time. Prototype the shape. The top and bottom parts of the completed preform are cut to produce a thin cylindrical molded body. In addition, in the method shown in FIG. 7, 21 is a material tube made of polyester, 22 is a tube end for supplying pressure fluid, and 2
3 is supply p-ra. 24 cylindrical heating devices, 26 stretching rollers. F-1〇-27 is a 4-increase device, in which a material tube 21 [while supplying pressure fluid from its tube end 22, is supplied at a constant speed from a supply R-ra 23, and is guided to a cylindrical heating device [24]. This is heated to the drawing temperature. The material tube is subjected to a circumferential force of 1'o! in the heating device 24! The ρ-ra 26 which is expanded and stretched at a faster speed than the supplied p-ra is also stretched in the longitudinal direction by 4 extensions @ 27K. The 4-increasing device f27 grips the forming tube and simultaneously closes it 4 and seals the pressure fluid. The sealed portion of the 4-increased molded tube is cut and the cylindrical molded product is changed. [Example] Hereinafter, the present invention will be explained in detail with reference to Examples. The measurement conditions for the main physical property values are as follows. il+ Intrinsic viscosity rrv): Measured at 35°C using 0-reap phenol as a solvent. (2) Density [ρ]: Measured at 30°C in a density gradient tube made from carbon tetrachloride and n-hebutane. (3) Refractive index [n]: Attach a polarizing plate to the Atsube refractometer and measure the refractive index in the thickness direction and plane direction of the sample cut out from the molded body at a temperature of 25°C.
Sodium D#! Measured using. (4) Vertical crack strength: The cut plane parallel to the axis of the compact was deformed to various radii of curvature at 20°C, and the radius of curvature at which vertical cracks occurred was measured. (51 Surface roughness CLA (Center Line Average)) According to JIS BO6011c, using a stylus type surface roughness meter (Surcom 3 B) manufactured by Tokyo Seimitsu Co., Ltd. Under the conditions of a radius of 2μ and a load of 0.19p, draw a film roughness curve, cut out a part of measurement length L in the direction of its center line, and set the center line of this cut out part on the X axis and the vertical magnification. When expressed as a roughness curve (Y=f) with the direction of Y being the Y axis, the value given by the following equation is expressed in μ scale units. In this measurement, 8 pieces were measured with a reference length of 0.25 mm, 3 pieces were excluded from the direction with the largest value, and the average value of the 5 pieces was expressed. Examples 1 to 5 and Comparative Example 1 A PET chip (IVO shown in Table IK) was dried with hot air at 160°C for 5 hours to reduce the moisture content in the chip to about 0.005 wt. , an extruder V equipped with a die having a slit-like void at the tip.
C# dry chips are supplied, and the extruded *PET sheet is immediately cooled by water cooling in a stainless steel drum kept at a temperature of about 20°C KW4 to give a thick 200#, ρ=1.
33j'/cII, an amorphous PET sheet of IV shown in Table 1 was obtained. The sheet was sandwiched and fixed from above and below with a frame with a 100 x 100 m square hole, and the center of the sheet was heated to approximately 130°C by a ring-shaped heater.
Heating layer, the diameter of the tip and root part is 32mm and 34M, the length is 125u, the sheet is made by a plug mold with a temperature of 120℃, the diameter of the bottom and top part is 36111 and 37N.
, a depth of 12,711 m + a temperature of 60°C, pressure inside the mold cavity was pushed, a sheet of compressed air of 5 k#/cdG was blown from the plug mold to the cavity mold, and after holding for about 5 seconds, the pressure inside the molded body was reduced. The pressure was reduced to normal, the mold was opened, and a cylindrical molded body with a bottom was expanded. The above molding outline is shown in FIG. 1. Examples of the axial thickness distribution and orientation degree distribution of the obtained molded body are shown in FIGS. 3 and 4, respectively. Figure #I2 is a cross-sectional view of the bottomed cylindrical molded body, where D is the flange surface, E is the bottom, and the numerical value on the side surface indicates the distance (S[3)) from the flange surface. 3 to 5 show the wall thickness distribution TH [μ]1 of the molded bodies of Examples 2 and 4, the degree of orientation in the circumferential direction mnx-z (the refractive index in the circumferential direction nz and the refractive index in the thickness direction nz14- The distribution of the axial orientation degree ny-7 (difference between the refractive index and nz in the axial direction) is shown, and the numbers 2 and 4 in the graph are the measurements of the molded product of Example 2.4 Show value. 794
In the figure, from the 7 rank surface to 2 (! II level (area A),
Δnx-, < 0.03. In the range from about 2 to 43 (region B), 0.03≦munX
-Z≦o, o a , in the range of about 4cx or more (region C), ΔnX-Z > 0-04. Furthermore, the cylindrical part of the molded body was cut open, and the sample of Example 4 was placed between orthogonal polarizing plates, and the distortion was observed. The results are shown in FIG. In FIG. 6, the numbers 0 to 10 each indicate the distance (3) from the flange surface, and the curved line in the figure shows the outline of a good interference pattern caused by distortion. In Figure 6, A' is an area where axial strain occurs, C' is an area where circumferential strain occurs, and B' is an area where axial and circumferential strains are mixed. This almost coincides with the region A-C according to the range of Δnz-2 explained in FIG. Next, each part of the cylindrical molded body was bent with the axial direction as an axis, and it was examined to what extent vertical cracking would occur when the radius of curvature was set to 0.5 fins or less. The results are shown in Table-1. Table-1 As is clear from Table-1 (if the IV of Comparative Example 1 is lower than 0.50, vertical cracks will occur in any part of 50 or more, making it unusable. ■ is about 0.60 If it is above, area C
If the part is used as a cylindrical body, there will be no problem of warping, and if the IV is about 0.70 or more, there will be no ** in any part -1 Examples 6 to 9 and Comparative Examples 2 and 3 Unstretched polyester sheet Cylindrical molded bodies with different wall thicknesses were obtained in the same manner as in Example 2, except that the wall thicknesses of the molded bodies were changed. KA71 was deposited on the surface of the skeleton molded body, and an electrostatic metal surface roughness meter (manufactured by Metrol Co., Ltd., trade name: Surf Touch,
The sensor has a size of 3 tm x 9 cm, and is modified to a low-load second sensor pressing pressure mechanism of a flat surface / dust type TP-401 type), and a 7'CfAllAll button device is used to improve the adhesion between the surface of the molded object and the sensor. Rating: 11t. The results are shown in Table-3. 17-1) The measurement principle of this surface roughness meter is that the capacitance changes depending on the space ratio between the object to be measured and the metal electrode, and the space ratio is measured using the liquid crystal display (full scale 32). It is of the type. Therefore, if the adhesion between the electrode and the molded body is poor, the number of liquid crystal indications will decrease. Examples 10 to 12 and Comparative Example 4 A cylindrical molded body with a bottom was molded in the same manner as in Example 2, except that a rod-shaped heater was used instead of a ring-shaped heater during pressure forming, and K was used as a comparative example. . Only the cylindrical portion was cut out from the obtained bottomed cylindrical molded body, and the wall thickness in the circumferential direction and the roundness of the cylindrical portion were measured. The results are shown in Table-3. 18-Table-3 Example] If the difference between the maximum and minimum wall thickness in the circumferential direction is within 30 μ as shown in 0 to 12, the difference between the longest diameter and the shortest diameter of the cylindrical portion is within one company. While the roundness is good, when the wall thickness difference exceeds 30μ as in Comparative Example 4, the roundness becomes extremely poor. Examples 13 to 15 and Comparative Example 5 PET-F-7 blocks with rv=o and as were dried for 5 hours in a hot air dryer at 160°C to reduce the moisture content in the chips to 0.0.
After adjusting the cylinder diameter to about 05 wt-30mm
! Cylinder length/cylinder diameter = 22, dry chips were supplied to an extruder equipped with a tube die at the E end, and the cylinder and die temperature was 275 to 300 °C.
The tube was extruded and immediately solidified by cooling with water to obtain an amorphous PET tube with an outer diameter of 9mm and a wall diameter of 0.6u. The skeleton tube had IV = 0.60 and ρ = 1.33. The tube is stretched and expanded by the method described above using the apparatus shown in FIG. 7, and the sealed portion is cut to form a cylindrical molded body fc. The temperature of the hot water in the heater is 98°C, the stretching ratio in the longitudinal direction is changed by adjusting the rotation speed of the supply roller and the pulling roller, and the stretching ratio in the circumferential direction is 98°C. The sound can be changed by changing the inner diameter of the vibrator (Fig. 7, 28).The results of measuring the degree of alignment and strength of the obtained molded body are shown in Table-4. The test was carried out in the same manner as in the case of longitudinal tear strength except that the degree of orientation was less than 0.03, the strength was extremely reduced. Examples 16 to 18 and Comparative Example 6 Except for adding an additional amount of lubricant, the same procedure as in Example 2 was carried out to obtain a bottomed cylindrical molded body having different roughness on both surfaces. The bottom part of the molded body was inserted into the opening of another molded body and the molded body was stacked with weight, and then the two molded bodies were separated again.The occurrence of scratches and the slipping property are shown in Table 5. Table 5 The surface properties of the samples of Examples 16 to 18 measured by a three-dimensional roughness meter are as follows:
Although it had the same roughness as the T film, Comparative Example 6
had protrusions of about 5 to 8 μm, and was poor as a magnetic recording carrier. As explained above, the molded article of the present invention is thin and has good thickness distribution and surface smoothness, and can be used for mechanical purposes.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic diagram of thermoforming of a sheet that can be used in the present invention, and FIG. 2 is a cross-sectional view of a bottomed cylindrical molded product;
Fig. 3 shows the wall thickness distribution of the cylindrical molded body according to the present invention, Figs. FIG. FIG. 7 is a schematic diagram of another method for obtaining a molded article of the present invention, showing a method of cutting a tubular PET after stretching and expanding it. 23- Ri9:♀ 9QQ? -&LL7

Claims (1)

[Claims] 1. A cylindrical molded body made of polyester whose main repeating unit is ethylene terephthalate and whose intrinsic viscosity is 0.5 or more, the molded body having a wall thickness of 100μ or less and parallel to the axis. The difference between the maximum wall thickness and the minimum wall thickness of the cross section is 30 μ or less, and the circumferential surface roughness [CLA (unit: 2 μ)] of the inner and/or outer surface of the molded body is 0.05 or less,
A thin cylindrical molded article made of polyester having an orientation degree of 0.03 or more in both the axial direction and the circumferential direction. 2. The thin cylindrical molded article made of polyester according to claim 1, wherein the polyester has an intrinsic viscosity of 0.7 or more.