JP2002097276A - Thermoplastic resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin film with reduced fluctuation of thickness and good quality while maintaining productivity. SOLUTION: This thermoplastic resin film is composed of a resin having at least a peak in the range of 0.12 ppm to 0.18 ppm on the measurement of 1HNMR.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin film having very high uniformity of thickness without any defects in a base line or the like.

[0002]

2. Description of the Related Art Thickness uniformity is one of important basic qualities for a thermoplastic resin film. For example, when polyester is used as an example, polyester film has excellent properties, and therefore, it has excellent properties, such as a base film for a magnetic recording medium, an electrical insulating use such as a capacitor film, an OA use such as a printer ribbon, and a heat-sensitive stencil printing by punching with heat. Although it is used in various applications such as base paper, in these applications, a high dimensional accuracy of the film thickness is required year by year. For example, in the field of printer ribbons, further high-definition printing is required along with the trend toward full-color printing, and it is necessary to reduce uneven printing.
If there is uneven thickness in the base film, when it becomes an actual ink ribbon, the amount of heat conduction from the print head will vary depending on the thickness unevenness of the base film, which may cause uneven printing. There is a demand for reduction in film thickness unevenness. In addition, when the thickness unevenness is deteriorated, physical properties unevenness due to the film thickness is caused, which leads to deterioration in product quality. In addition, even when it is not directly related to the quality of the product, troubles in processing the film into a product and deterioration of the winding shape when winding in a roll shape, and thus, the quality of the processed product is caused to deteriorate, which is not preferable. .

By the way, a method of molding into a thermoplastic resin film generally involves melting a resin with an extruder, removing foreign matter through a filter or the like, and then forming a slit in accordance with the form of the film to be molded. It is discharged from a die (base) and continuously formed on a rotating roll (casting drum) through which a cooling medium passes. At this time, an electrostatic force is often applied to bring the resin film into close contact with the casting drum. Further, in order to increase the strength of the film, the obtained cast film is generally stretched in the longitudinal direction and the width direction of the film.

[0004] Here, the causes of the thickness unevenness of the film are caused by fluctuations in the discharge amount when melt-extruded and extruded into a sheet on a casting drum, and the molten state between the die and the casting drum (between L and D). Examples include film vibration of a certain resin film, fluctuation of a landing position due to insufficient adhesion when the molten resin is brought into close contact with the casting drum, and uneven rotation of the casting drum. In the case of an oriented film, furthermore, uneven roll temperature and uneven rotation during longitudinal stretching (longitudinal stretching), and uneven temperature and wind speed in the tenter during transverse stretching (longitudinal stretching). and so on.

[0005] Therefore, various methods have conventionally been proposed for improving thickness unevenness. For example, in order to suppress the rotation unevenness of the casting drum for cooling and solidifying the molten resin (Japanese Patent Laid-Open No. 55-93420) and to suppress the film vibration between LDs, the extrusion temperature of the thermoplastic resin is lowered to melt the resin. Method of increasing viscosity (Japanese Patent Application No. 6-70789)
However, further reduction in thickness unevenness is required.

[0006]

In any case, in order to improve the thickness unevenness of the thermoplastic resin, the thickness unevenness in the casting process, which is a process of rapidly cooling and solidifying the molten extruded sheet discharged from the die, is required. It is known that the reduction is effective, and that the reduction of the draft ratio at this time is effective (Japanese Patent Application Laid-Open No. 10-217315). However, if the lip gap of the base is narrowed to reduce the draft ratio, a streak-like defect called a base streak occurs, which not only leads to a decrease in quality, but also becomes a serious drawback in severe cases and cannot be adopted as a product. It also leads to a decline in sex.

As described above, there is a strong demand for improving the film thickness unevenness, and various improvement methods have been proposed for that purpose, but the effect is still insufficient, and troubles with the film thickness unevenness cannot be tolerated. .

The present invention has been made in view of the background of the prior art,
It is an object of the present invention to provide a thermoplastic resin film having good quality and maintaining productivity while reducing thickness unevenness of the film.

[0009]

The present invention employs the following means in order to solve the above-mentioned problems. That is, the thermoplastic resin film of the present invention has ¹ H
When NMR measurement was performed, 0.12 ppm or more and 0.18 ppm or more
It is characterized by being composed of a resin having at least a peak in the range of ppm or less.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has been studied diligently with respect to the above-mentioned problems, that is, a thermoplastic resin film which is reduced in uneven thickness, suppresses the occurrence of die streaks, has good quality, and maintains productivity. When using a thermoplastic resin having at least a peak in a specific range of 0.12 ppm or more and 0.18 ppm or less when performing ¹ HNMR measurement, it was found that such a problem could be solved at once. is there.

In the present invention, the thermoplastic resin must have at least a peak in the range of 0.12 ppm to 0.18 ppm when measured by ¹ HNMR. The shape of the peak may be a single peak, a double peak, a triple peak, or a multi-peak. In the case of such a thermoplastic resin, in order to improve the thickness unevenness, even if the draft lip gap is narrowed and the draft ratio is reduced, the thermoplastic resin in a molten state is less likely to adhere to the lower surface of the die, and the occurrence of die streaks is suppressed. it can. That is, according to the present invention, it is possible to achieve both improvement in unevenness in thickness and reduction of streaks in the base.

When ¹ HNMR measurement was performed, the value was 0.1%.
A resin having at least a peak in the range of 12 ppm or more and 0.18 ppm or less is obtained by adding a release agent such as a silicone oil or a fatty acid ester to the resin, and Such special peaks appear when they are dispersed and distributed in the resin. That is, when the release agent is not finely distributed in the resin, not only is the effect of suppressing the die streak small, but the aggregated release agent becomes a defect in the film,
It is not preferable because the quality as a film is impaired. The addition of silicone oil or the like, which is an example of the present invention, is already known from JP-B-52-48898 and JP-B-3-60858, but the dispersion state is non-uniform and relatively large. Due to the particle shape, the aggregated silicone oil often becomes a crater-like defect, and in severe cases, the transparency often deteriorates.

However, the resin having a specific peak according to the present invention has no silicone oil so far and is finely dispersed in the film, and does not cause crater-like defects or deterioration in transparency. The film is characterized in that a very high-quality film can be obtained and a higher effect of suppressing die streaks can be obtained.

The thermoplastic resin constituting the thermoplastic resin film of the present invention preferably further satisfies the following formula 1 from the standpoint of the effect of suppressing die streaks.

0.05 ≦ X / Y ≦ 50 (Formula 1) X: Area of a peak existing in a range of 0.12 ppm to 0.18 ppm Y: Area of a reference peak More preferably, 0.05 ≦ X / Y ≦ 50, more preferably 0.1 ≦ X / Y ≦ 25.
When X / Y is smaller than 0.05, the releasability of the thermoplastic resin from the die is not sufficient, and the effect of suppressing the line of the die is small, which is not preferable. When X / Y is larger than 50, a defect may be generated inside the thermoplastic resin film. A thermoplastic resin that satisfies the condition of Formula 1 is excellent in releasability, so that dirt on the lower surface of the base, which causes base lines, is sharply reduced, and thus the base line has a high effect of suppressing base lines. For this reason,
Even if the draft lip gap is narrowed to reduce the draft ratio and the thickness unevenness is improved, it is possible to suppress a decrease in productivity due to the die stripe.

The thickness unevenness of the thermoplastic resin film of the present invention in the longitudinal direction of the film is preferably 10% or less,
It is more preferably at most 9%, particularly preferably at most 8%. When the thickness unevenness in the longitudinal direction of the film is 10% or less, generation of wrinkles when processing the thermoplastic resin film can be suppressed, and when used for an ink ribbon base film, print unevenness can be reduced. Good.

Examples of the thermoplastic resin in the present invention include polyolefin resins such as polyethylene, polypropylene and polymethylpentene, nylon 6, nylon 6 and the like.
6, such as polyamide resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,
A polyester resin such as 6-naphthalate, a polyacetal resin, a polyphenylene sulfide resin, and the like can be used.

Particularly, the use of polyester is preferred because the effects of the present invention are highly exhibited. Above all, polyethylene-2,6-naphthalate and polyethylene terephthalate are preferable, and particularly polyethylene terephthalate is inexpensive, so that it is used in a wide variety of applications and has a high application effect. These resins may be homo resins, copolymer resins or blends. Also, in these resins, various additives, for example,
An antioxidant, an antistatic agent, a crystal nucleating agent, inorganic particles, organic particles, a viscosity reducing agent, a heat stabilizer, a lubricant, a foam nucleating agent, and the like may be added.

The polyester in the present invention is a polymer obtained by condensation polymerization of a dicarboxylic acid and a diol. Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, adipic acid and sebacic acid. And diols such as ethylene glycol, trimethylene glycol, tetramethylene glycol, cyclohexane dimethanol, polyalkylene glycol, and bisphenol A ethylene oxide adduct. Things can be used.

Specific examples of the polyester include polymethylene terephthalate, polyethylene terephthalate, polytetramethylene terephthalate, polyethylene-p-oxybenzoate, poly-1,4-cyclohexylene dimethylene terephthalate, and polyethylene-2,6-. Naphthalate or the like can be used.
Among them, polyethylene terephthalate or polyethylene naphthalate is particularly preferably used. Of course, these polyesters may be either homopolymers or copolymers. Examples of copolymerization components include diethylene glycol, neopentyl glycol, polyalkylene glycol, and bisphenol A.
A diol component such as an ethylene oxide adduct and a dicarboxylic acid component such as dimer acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid can be used.

It is preferable that the thermoplastic resin of the present invention contains at least one release agent selected from fatty acid esters and silicone oils. Such fatty acid esters include, but are not limited to, alkyl carboxylic acid esters, oxidized waxes, vegetable waxes, polyoxyethylene alkyl esters, phosphate esters, synthetic lubricating oils, polyethylene waxes, and the like. On the other hand, as the silicone oil, polydimethylsiloxane, polyphenylmethylsiloxane, polyalkylphenylsiloxane, polyalkyl-modified siloxane, polyether-modified siloxane, polyfatty acid ester-modified siloxane, and the like are used. These are not particularly limited to homopolymers, but may be copolymers. Among such silicone oils, those which are non-crosslinked silicone oils are preferred.

The amount of the release agent added is preferably 0.0001% to 0.3% by weight, more preferably 0.0002% to 0.05% by weight, and particularly preferably 0.0003% to 0. Not more than 02 wt%. When the amount of the silicone oil added is 0.0
If the content is less than 001 wt%, the effect of reducing the base line is not preferred. On the other hand, if the amount exceeds 0.3% by weight, it becomes difficult to finely disperse the release agent, which is not preferable.

First, as the thermoplastic resin, a resin to which silicone oil or fatty acid ester is added at the time of polymerization, or a resin to which silicone oil or fatty acid ester is added at a high concentration at the time of polymerization, are further optionally added by a twin-screw kneader or the like. Can be used. Further, these may be used as a master chip, and a resin further diluted to an arbitrary concentration may be used as necessary.

The raw material of such a thermoplastic resin is prepared in the form of pellets or the like, and, if necessary, is pre-dried in hot air or under vacuum and supplied to an extruder. In the extruder, the resin heated and melted to a melting point or more is connected in a molten state to a filter, a gear pump, and the like, thereby improving the uniformity of the resin extruded amount, and is highly effective in reducing thickness unevenness. However, the component of uneven thickness improved by the gear pump is a component having a long period such as a frequency of 0.1 Hz or less, and the introduction of the gear pump alone cannot achieve the reduction of the uneven thickness component as the object of the present invention.

If necessary, it is also preferable to introduce a static mixer or the like into the flow path from the extruder to the die. As a result, the silicone oil and the fatty acid ester are further finely dispersed, and the effect on the reduction of die streaks increases.

The resin sent from the extruder to the die is discharged after being formed into a desired shape by the die. Here, the die is not particularly limited. For example, as described in Keiji Sawada, “Plastic extrusion molding and its application” (Seibundo Shinkosha Co., Ltd.), a cylindrical groove (manifold) is used. ), A manifold die (also referred to as a T die),
Any of a fish tail die (also referred to as a T die) shaped like a fish tail and a coat hanger die shaped between them may be used. The flat die is a land called a die hopper which spreads the molten resin in the width direction, and a land which is a final portion which is formed into a desired shape after the resin is spread in the width direction and which has a constant slit gap. It is composed of parts called parts. Immediately after passing through the land, the resin is released to the atmosphere and is extruded onto a casting drum. At this time, in the present invention, the portion of the die where the molten resin comes into contact, especially the material of the land portion of the die and the lower surface of the die land are hard chrome plated,
Micro crack hard chrome plating, amorphous chrome plating, titanium compounds such as TiN, TiCN, TiC, chromium nitride, diamond-like carbon, cubic boron nitride, tungsten carbide, stainless steel, iron, ceramics, Teflon (registered trademark), nickel It is preferable to use alloys, aluminum alloys, and the like, or composite materials thereof, for example, nickel alloy + Teflon, ceramics + Teflon, and the like. On the other hand, as the surface condition, the maximum height of the surface roughness is preferably from 0.16 μm to 2.0 μm, and more preferably a honing treatment is performed.

The molten resin extruded on the casting drum is brought into close contact with a cooling body such as a casting drum by electrostatic force using a wire-shaped, tape-shaped, needle-shaped or knife-shaped electrode, and is rapidly cooled and solidified. A film with very excellent thickness uniformity is obtained.

The casting film thus obtained may be biaxially oriented as required. The term "biaxially oriented" in the present invention means that the film is oriented in the longitudinal direction and / or
Alternatively, it means that the film is stretched in the transverse direction to give molecular orientation in the biaxial direction. In addition, the film may be stretched in the vertical and / or horizontal direction again to give a stronger orientation.

The term "longitudinal stretching" in the present invention refers to stretching for giving a film a molecular orientation in the longitudinal direction, and is usually performed by a difference in peripheral speed of a roll. This stretching may be performed in one stage, or may be performed in multiple stages using a plurality of roll pairs. Although the stretching magnification varies depending on the type of the resin, it is usually about 2 to 15 times. In particular, when polyethylene terephthalate is used, the ratio is about 2 to 7 times.

In the present invention, the term “lateral stretching” refers to stretching for imparting a film with orientation in the width direction.
Using a tenter, the film is conveyed while holding both ends of the film with clips, and is stretched in the width direction. The stretching magnification varies depending on the type of the resin, but is usually about 2 to 10 times.

In order to impart flatness and dimensional stability, the biaxially stretched film may be subjected to a heat treatment at a stretching temperature or higher and a melting point or lower in a tenter, and may be uniformly cooled, cooled to room temperature, and wound up. . In the present invention, simultaneous biaxial stretching may be performed. <Evaluation Method of Physical Properties> (1) ¹ HNMR Measurement HMB (hexamethylbenzene) was used as a reference substance. The reference peak position is 2.12p
pm. ¹ HNMR measurement was performed at an observation frequency of 599.
7MHz Varian Unity INOVA60
The measurement was performed with a type 0 at a measurement temperature of 45 ° C. As a measurement sample, a film sample amount of 0.1 g (± 0.01) was measured using a solvent (H
FIP-d2: 400 μL CDCl3: 300 μL
HMB: 0.022 μg). In addition, the standard of the 0 peak was the TMS standard. flip a
The angle is set to 45 °, pulse irradiation is applied, and the observation width is 8 kHz.
z · Repeat time 7.0 sec. I went in.

Note that the PET signal is obtained by a wet method (wate method).
The measurement was performed with elimination by r suppression enhanced through T1 effects). The WET method was performed with reference to the following literature.・ RJOgg, PBKingsley, JSTaylor, J.Magn.reson.
B 104,1 (1994) ・ SHSmallcombe, SLPatt, PAKeifer, J.Magn.res
on. 117,295 (1995) (2) Thickness irregularity Anritsu Corporation film thick nest tester “KG6
01A "and an electronic micrometer" K306C "are used to continuously measure the thickness of a film sampled 30 mm wide and 25 m long in the longitudinal direction of the film. The transport speed of the film was 3 m / min. From the maximum thickness Tmax (μm) and the minimum value Tmin (μm) at 25 m length, R = Tmax−Tmin is calculated. From R and the average thickness Tave (μm) at 25 m length, the thickness unevenness (%) = R / Tave × 100. Asked. The thickness unevenness was an average value of 10 measurements. (3) Cap streak The cap streak was visually determined on the molten cast film 48 hours after the start of film formation.

"◎" indicates that no base streak is found, "○" indicates one to three base streaks, "△" indicates three to ten base streaks, and "を" indicates ten or more base streaks. X ". (4) Intrinsic viscosity Polyester is dissolved in o-chlorophenol, and 25 ° C.
Was measured.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on embodiments. Example 1 Polyethylene terephthalate having an intrinsic viscosity of 0.65 was used as a thermoplastic resin, and colloidal silica was added as particles at 1 wt%. This polyethylene terephthalate has 0.0005% by weight of polydimethylsiloxane added at the start of the polycondensation reaction. By doing so, even under vacuum during the polycondensation reaction, polydimethylsiloxane is hardly discharged out of the reaction system, and is very finely dispersed in polyethylene terephthalate. The thermoplastic resin pellets were vacuum-dried at 180 ° C. for 3 hours and then supplied to an extruder.
The mixture was melted at 280 ° C. by an extruder and supplied to a molding die via a gear pump and a filter pack. The die lip gap was 1.0 mm. The film extruded from the die is applied with electrostatic force and the surface temperature is adjusted to 25.
It was quenched and solidified on a casting drum kept at a temperature of ° C. A wire-like electrode was used as the electrode when applying static electricity. The resulting cast film was then heated with a group of rolls set at 110 ° C., stretched 5.8 times in the machine direction,
After being guided to a tenter and preheated with hot air at 120 ° C., the film was stretched 3.6 times in the transverse direction, heat-treated in a tenter with hot air at 235 ° C., gradually cooled to room temperature, and wound up. The film forming speed was 350 m / min. Met.

The thickness of the obtained film was 4.5 μm, and the thickness unevenness was 6.0%. In addition, the cap streak was “○”. As a result of ¹ HNMR measurement of the thermoplastic resin film of Example 1, a single peak was observed at 0.17 ppm, and X / Y was 0.25. Table 1 shows the obtained results. Example 2 The same apparatus and conditions as in Example 1 were used, except that 0.0005 watts of polymethylphenylsiloxane was used as the thermoplastic resin.
A mixture obtained by adding 1% by weight of colloidal silica to polyethylene terephthalate having an intrinsic viscosity of 0.65 added at the start of the polycondensation reaction and adding t% was used. The thickness of the obtained film was 4.5 μm, and the thickness unevenness was 6.
7%. In addition, the cap streak was “○”. As a result of ¹ HNMR measurement of the thermoplastic resin film of this example, a multipeak was observed at 0.13 ppm, and X
/ Y was 1.0. Table 1 shows the obtained results. Example 3 The same apparatus and conditions as in Example 1 were used, except that 0.0005 wt% of polydiphenylsiloxane was used as the thermoplastic resin.
Was added to polyethylene terephthalate having an intrinsic viscosity of 0.65 added at the start of the polycondensation reaction, and colloidal silica was further added as 1 wt% particles. The thickness of the obtained film was 4.5 μm, and the thickness unevenness was 6.1%.
Met. In addition, the cap streak was “○”. As a result of ¹ HNMR measurement of the thermoplastic resin film of this example, a multipeak was observed at 0.13 ppm, and X / Y
Was 1.2. Table 1 shows the obtained results. Example 4 The same apparatus and conditions as in Example 1, except that polyethylene terephthalate having an intrinsic viscosity of 0.65 obtained by adding 0.005 wt% of polydimethylsiloxane as a thermoplastic resin at the start of the polycondensation reaction, and further comprising colloidal silica 1w
What added t% as a particle was used. The thickness of the obtained film was 4.5 μm, and the thickness unevenness was 6.1%. In addition, the cap streak was “金”. As a result of ¹ HNMR measurement of the thermoplastic resin film of this example, a multipeak was observed at 0.13 ppm, and X / Y
Was 2.5. Table 1 shows the obtained results. Comparative Example 1 The same apparatus and conditions as in Example 1 were used except that colloidal silica was contained as a thermoplastic resin in an amount of 1 wt% and an intrinsic viscosity of 0.1%.
65 polyethylene terephthalate was used. The thickness of the obtained film was 4.5 μm, and the thickness unevenness was 6.
1%. In addition, the cap streak was “x”. As a result of ¹ HNMR measurement of the thermoplastic resin film of this example, no peak was observed in the range of 0.12 ppm or more and 0.18 ppm or less. Table 1 shows the obtained results. Comparative Example 2 The same apparatus and conditions as in Comparative Example 1 were used, except that the die lip gap was 2.5. The thickness of the obtained film is 4.5μ.
m, and the thickness unevenness was 15%. The streak was “△”. As a result of ¹ HNMR measurement of the thermoplastic resin film of this example, no peak was observed in the range of 0.12 ppm or more and 0.18 ppm or less. Table 1 shows the obtained results.

[0036]

[Table 1]

[0037]

According to the present invention, it is possible to obtain a thermoplastic resin film having a small thickness unevenness, suppressing the occurrence of streaks, and having good quality and high productivity, particularly optimal as a base film for a print ribbon. Can be provided.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08L 83/12 C08L 83/12 91/06 91/06 101/00 101/00 F term (reference) 4F071 AA02 AA15 AA20 AA21 AA40 AA44 AA45 AA46 AA54 AA55 AA62 AA67 AA71 AC10 AE11 BB08 BC01 BC12 BC15 4J002 AE032 BB031 BB121 BB171 CB001 CF041 CF051 CF061 CF071 CF081 CF101 CL011 CL031 CN011 CP032 CA052 CP182E 163 163

Claims (7)

[Claims] 1. When ¹ H NMR measurement is performed, 0.12 p
A thermoplastic resin film comprising a resin having at least a peak in the range of pm to 0.18 ppm. 2. The thermoplastic resin film according to claim 1, wherein the area of the peak satisfies the following equation (1). 0.05 ≦ X / Y ≦ 50 (Equation 1) X: Area of peak present in the range of 0.12 ppm to 0.18 ppm Y: Area of reference peak 3. The thermoplastic resin film according to claim 1, wherein the thickness unevenness of the thermoplastic resin film in the longitudinal direction of the film is 10% or less. 4. The thermoplastic resin film according to claim 1, wherein said thermoplastic resin is made of polyester. 5. The thermoplastic resin film according to claim 1, wherein said thermoplastic resin film contains a release agent. 6. The release agent is at least one selected from silicone oils and fatty acid esters.
4. The thermoplastic resin film according to item 1. 7. The thermoplastic resin film according to claim 1, wherein said thermoplastic resin film is biaxially stretched.