JPH02251854A - Biaxially stretched polyester film for photoresist - Google Patents

Abstract

PURPOSE:To provide the polyester film having the characteristic that the film hardly curls with methylene chloride by specifying the shrinkage rate of the film after the film is subjected to a treatment under specific conditions. CONSTITUTION:The shrinkage rate obtd. after the polyester film is immersed for 60 seconds in the methylene chloride kept at 20 deg.C and is dried for 24 hours under the temp. and humidity conditions of 23 deg.C and 50RH is determined to satisfy equation alphaMD+alphaTD<=1.4. {alphaMD: the shrinkage range (%) in the longitudinal direction, alphaTD: the shrinkage rate (%) in the transverse direction.} The sum of this shrinkage rate is preferably >=-0.1% and <=1.2% and is further preferably >=-0.1% and <=1.0%. The value of the shrinkage rate alphaTD in the transverse direction is <=0.7%, more preferably >=-0.1% and <=0.6%, more particularly preferably >=-0.1% and <=0.5%. The photoresist film of a solvent development type has the characteristic that the film hardly curls at the time of removing the polyester layer from the photosensitive layer by treating the film with the methylene chloride.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a biaxially oriented polyester film for photoresists, and more specifically, in a solvent-developed photoresist film, the polyester layer is removed from the photosensitive layer by chlorination before development. The present invention relates to a two-wheel stretched polyester film that is resistant to curling when removed by treatment with methylene.

[Prior Art and Problems to be Solved by the Invention] Biaxially stretched polyester films have excellent heat resistance, mechanical properties, chemical resistance, etc., and are therefore rapidly in demand as base films for photoresists.

Incidentally, in a solvent-developed photoresist film, there is a step of removing the polyester layer from the photosensitive layer by treating it with methylene chloride before development, but in this step, the film curls toward the photosensitive layer. When this degree of curl is significant, development may be hindered, which is a very serious problem. Therefore, there is a strong demand for the development of a polyester film that is resistant to curling even when the film is treated with methylene chloride.

[Means to solve the problem]

As a result of intensive studies in view of the above-mentioned problems, the present inventors have discovered that a film having certain specific physical properties has the property of being resistant to curling when exposed to methylene chloride, and has thus arrived at the present invention.

That is, the gist of the present invention is that 60%
A biaxially stretched polyester film for photoresist is characterized in that the shrinkage rate after being immersed for seconds and then dried under temperature and humidity conditions of 23° C. and 50% RH for 24 hours satisfies the following formula [1].

αNil+α7D≦1.4 (2) The present invention will be explained in more detail below.

Polyester as used in the present invention refers to aromatic dicarboxylic acids such as terephthalic acid isophthalic acid and naphthalene-2,6-dicarboxylic acid, or esters thereof and diols such as ethylene glycol, diethylene glycol, tetramethylene glycol, and neopentyl glycol. It is a crystalline aromatic polyester that can be obtained by polycondensation of

Such polyesters can be obtained by directly polycondensing aromatic dicarboxylic acids and glycols, or by polycondensing aromatic dicarboxylic acid dialkyl esters and glycols after transesterification, or by polycondensing diglycol esters of aromatic dicarboxylic acids. It can also be obtained by a method such as condensation.

Typical polymers include polyethylene terephthalate, polyethylene-2,6-naphthalate, polytetramethylene terephthalate, and polytetramethylene-
2,6-naphthalate, etc. For example, polyethylene terephthalate or polyethylene-2,6-naphthalate is not only a polyester in which terephthalic acid or naphthalene-2,6-dicarboxylic acid and ethylene glycol are bonded, but also 80 moles of repeating units. A copolymerized polyester in which 20 mol% or less of repeating units consisting of ethylene terephthalate or ethylene-2゜6-naphthalate units is other components, or a mixed polyester obtained by adding and mixing other polymers to these polyesters. .

In addition, in the present invention, in order to impart properties that make it more difficult for methylene chloride to curl, the raw material polyester has a molecular weight of 200 to 10,000, preferably 200 to 500.
It is preferable to mix and use an organic substance within the range of 0.

As the organic substance, aliphatic hydrocarbons, aliphatic esters, alkylene bis aliphatic amides, alkylene bis aromatic amides, etc. are preferably used.

The amount added is lOppm based on polyester.
The above is 1) 0000 pp or less. Preferably 20pp
m or more and 2000 ppm or less. More preferably 30
ppm or more 1) 000pp or less. If the amount is less than 10 ppm, the effect will be extremely small, and if it is more than 10,000 ppm, the lubricant may bleed out onto the film surface, which is inappropriate.

In addition, if the polymerization degree of the polyester is too low, the mechanical properties will deteriorate, so the intrinsic viscosity should be 0.40 or more, preferably O,SO~0.90, more preferably 0.55~0.
It is preferable to use a polymer having a degree of polymerization within the range of 0.85.

In the present invention, in order to impart slipperiness to the film,
Fine particles can be contained. Examples of fine particles that impart slipperiness include known inert external particles such as kaolin, clay, calcium carbonate, and silicon oxide. The amount of fine particles added is not particularly limited, but is usually 0.
It is preferable to contain 0 O5 to 2% by weight. Also,
The average particle diameter of the particles is preferably in the range of 0.005 to 5.0 μm.

In addition to these particles, dyes, pigments,
Compounds such as colorants, stabilizers, antistatic agents, conductive substances, antioxidants, and antifoaming agents may be added.

The inventors of the present invention investigated the factors that cause the film to curl after being treated with methylene chloride from various aspects, and found that in order to prevent such curling from occurring, the film should be immersed in methylene chloride at 20°C for 60 seconds. Then, after drying for 24 hours under the temperature and humidity conditions of 23° C. and 50% RH, the sum of the longitudinal shrinkage rate (α14Ill) and the transverse shrinkage rate (αTD) of the film (αMD+αTD) is 1.4. It has been found that it is extremely effective to control it to % or less. The sum of the shrinkage percentages is preferably -0.1% or more and 1.2% or less, more preferably -0.1% or more and 1.0% or less. If the sum of the shrinkage rates is greater than 164%, the degree of curl of the film after treatment with methylene chloride is large and unsuitable. If the sum of the shrinkage rates is less than -0.1%, that is, if the film swells, it will be difficult to maintain the flatness of the film when treated with methylene chloride.

In the present invention, the difference (α.-αa,) between the shrinkage percentage in the longitudinal direction and the shrinkage percentage in the lateral direction in the above shrinkage percentage is -0,2
% or more and 0.2% or less, preferably -0.1% or more and 0.1
It is best to keep it below %. If the difference in shrinkage rate is less than 10.2% or more than 0.2%, the anisotropy of the amount of shrinkage when the film is treated with methylene chloride is large and curling is likely to occur.

In the present invention, the value of the contraction rate αa in the lateral direction is 0.
．． 7% or less, preferably -0.1% or more and 0.6% or less,
Particularly preferably, the content is -0.1% or more and 0.5% or less. When a film having an α value exceeding 0.7% is unwound from a roll, treated continuously with methylene chloride, and then wound onto a roll, the degree of curl in the lateral direction becomes large, which is undesirable. In addition, if the amount of the film is less than 0.1%, flatness cannot be maintained during treatment with methylene chloride, which is not preferable.

According to the inventors' considerations, the reason why the film curls when one side of the film is treated with methylene chloride is thought to be mainly due to local shrinkage of the film due to methylene chloride, and the shrinkage rate must be adjusted appropriately. It is believed that by limiting the amount to a certain value, the curling of the film can be suppressed to a minimum.

In the present invention, the heat shrinkage rate in the width direction of the film when heat treated at 150t for 5 minutes is -0.1% or more and 0.1% or more.
It is preferably 5% or less, -〇.

It is more preferably 1% or more and 0.3% or less.

The heat shrinkage rate in the width direction of the film under the above conditions is -0,
If it is less than 1%, i.e., the film will swell, or if it is more than 0.5%, the shrinkage after treatment with methylene chloride will be large; The degree of curl of the film increases, which is inappropriate.

In addition, in the present invention, the plane orientation degree (ΔP) of the film
is preferably in the range of 0.150 to 0.180, more preferably in the range of 0.160 to 0.180. The plane orientation degree (8P) is less than 0.150 or 0.
For films exceeding 180, the degree of curl of the film after treatment with methylene chloride is large (and unsuitable).

Furthermore, in the present invention, the average refractive index (n) of the film
is preferably in the range of 1.6050 to 1.6085(7), more preferably in the range of 1.6060 to 1.6085. Average refractive index (di) is 1.6050
If it is less than that, the degree of curling of the film after treatment with methylene chloride becomes large, which is unsuitable.

Next, the method for forming the film of the present invention will be specifically described.

The film of the present invention usually contains the above-mentioned polyester with a 280%
A sheet is extruded from an extruder at a temperature in the range of ~320°C, cooled to a temperature of about 70°C or less to form a substantially amorphous sheet, and then the resulting sheet is rolled lengthwise and in the barrel direction.
It can be obtained by stretching 5 times or more to obtain a biaxially oriented polyester film, and then heat-treating the obtained film at a temperature in the range of 220 to 260°C.

Particularly, in order to increase the degree of plane orientation, it is preferable to apply longitudinal re-stretching and/or transverse re-stretching, widening during heat setting, longitudinal multi-stage stretching, etc.

In addition, especially during heat setting and during the cooling process after heat setting,
Applying a width relaxation of 0.1 to 25%, preferably 2 to 20% is also one of the preferred forms for obtaining the film of the invention. The film of the present invention can be obtained by appropriately selecting conditions within the above range, and its thickness is usually 50 to 200 μm, preferably 10 to 1)00 μm.

〔Example〕

The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples.

In addition, the evaluation method of the film is shown below.

(1) Evaluation of ease of curling of film when immersed in methylene chloride A roll-shaped evaluation film with a width of 300 mm and a length of 500 m was wound up at a tension of 0.5 kg/mm and a winding speed of 29.
Methylene chloride was applied to one side of the film at a rate of 1.0 ml/min, and then dried by blowing compressed air. The degree of curl of the film curled in the width direction on the side to which methylene chloride was applied was visually evaluated and classified into the following ranks.

Rank: ◎ (Extremely Good) Rank: ○ (Good) Rank: △ (Slightly Poor) Rank: × (Poor) (2) Method for measuring the shrinkage rate of a film when immersed in methylene chloride and dried at 20°C In methylene chloride, width 10 mm, length 150 m
Both sides of the evaluation film of m (gauge distance 100 mm) were immersed for 60 seconds. Thereafter, the film was dried for 24 hours under a temperature and humidity condition of 23° C. and 50% RH, and the shrinkage rate was calculated by the following formula by measuring the length between the gauge marks of the evaluation film.

Shrinkage rate (%) = (3) Heat shrinkage rate Calculated using the following formula by heat-treating the sample at 150° C. for 5 minutes under no tension and measuring the length of the sample before and after that.

Heating shrinkage rate (%) = (4) Degree of plane orientation and average refractive index The refractive index of the film was measured using a refractometer manufactured by Atago Corporation and a sodium lamp as a light source.

The maximum refractive index n in the film plane, the refractive index n5 in the direction perpendicular to it, and the refractive index n in the thickness direction were determined, and the degree of plane orientation and the average refractive index were calculated.

(5) Intrinsic viscosity (η) 1 g of polymer was mixed with phenol/tetrachloroethane-50
It was dissolved in 100 ml of a mixed solvent of 150 (weight ratio) and measured at 30°C using a drop viscometer.

Next, a method for manufacturing the films used in Examples and Comparative Examples will be described.

Example 1 5tOz of 1.3crm is 90ppm, -order particle size 30μ
A polyethylene terephthalate resin adjusted to have a SiO□ of 1)00 ppm and a hexamethylene bisbehenamide (organic lubricant) of 200 ppm was dried by a conventional method, melt-extruded at 290° C., cooled and solidified to obtain an amorphous sheet.

First, the above amorphous sheet was longitudinally stretched 2°9 times at 83°C, further longitudinally stretched 1.5x at 78°C, then transversely stretched 4.0x at 0°C using a tenter, and then The film was heat-set at 247° C. while being relaxed by 5% in the width direction to obtain a film with a thickness of 25 μm. Table 1 shows the physical properties and characteristics of the obtained film.

Example 2 1,3 pm of Sin, 60 ppm, -order particle size 30
A polyethylene terephthalate resin adjusted to have a S i Oz in μm of 120 ppm was dried by a conventional method, melt-extruded at 290° C., cooled and solidified to obtain an amorphous sheet.

First, the above amorphous sheet was longitudinally stretched 2.9 times at 83°C, then further longitudinally stretched 1.5 times at 78°C, and then 4.0 times transversely stretched at 1) 0°C using a tenter. 2 under tension fixation
Heat set at 47℃, then 8% in the middle direction at 220℃
A film with a thickness of 25 μm was obtained. Table 1 shows the physical properties and characteristics of the obtained film.

Comparative Example 1 The amorphous sheet of Example 2 was longitudinally stretched and transversely stretched under the same conditions as Example 2, and then heat-set at 247° C. under tension fixation to obtain a film with a thickness of 25 μm. Table 1 shows the physical properties and characteristics of the obtained film.

Comparative Example 2 The amorphous sheet of Example 2 was longitudinally stretched and transversely stretched under the same conditions as Example 2, and then stretched by 8% in the width direction at 220°C.
A film having a thickness of 25 μm was obtained by heat setting while giving relaxation. Table 1 shows the physical properties and characteristics of the obtained film.

〔Effect of the invention〕

According to the present invention, it is possible to produce a base film for a photoresist that is resistant to curling when a polyester layer is removed from a photosensitive layer by treatment with methylene chloride in a solvent-developed photoresist film, The value is high.

Claims (1)

[Claims] (1) The shrinkage rate after immersing in methylene chloride at 20°C for 60 seconds and then drying for 24 hours under the temperature and humidity conditions of 23°C and 50% RH satisfies the following formula [1]. Biaxially oriented polyester film for photoresist. α_M_D+α_T_D≦1.4...[1] [α_M_D; Vertical contraction rate (%) α_T_D; Transverse contraction rate (%)]