JPS5853418A - Preparation of polyester film - Google Patents

Abstract

PURPOSE:To obtain polyester film of a high young's modulus by a method wherein polyester having a property providing optically anisotropical molten material is extruded from a slit at a temperature higher than the temperature giving the minimum melting viscosity to make film. CONSTITUTION:Polyester having a property providing optically anistropical molten material is melted and extruded at a temperature higher than the temperature giving the minimum melting viscosity. The preferable melting extruding temperature is at least twenty degrees higher than the temperature indicating the minimum point. Temperature at which melting viscosity inidcates the minimum point differ according to the composition and polymerization of polyester and generally are centered at 330-400 deg.C. The film from the extrusion slit is oriented at first in the direction of machine axis and then in the direction at a right angle to the machine axis. In this way it is possible to obtain the polyester film having a high young's modulus, a high strength, uniform thickness, dimensional stability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing polyester films. More specifically, the present invention relates to a method for producing a high Young's modulus polyester film.

It has been known that when molded into a polyester sheet which has the property of forming an optically anisotropic melt, it exhibits an unexamined single layer. That is, by simply melt-spinning this polymer, the polyester molecules are highly oriented in the 1llt axis direction, resulting in a dark blue fiber with a high Young's modulus.

On the other hand, when this polyester is processed by the melting method, it is presumed that molecular orientation occurs in the extrusion direction when passing through the die slit. Films produced by extrusion using a T-die or the like using conventional methods tend to be highly oriented in the machine axis direction, so they have extremely high strength (e.g. 30 kg/'snJ) in the machine axis direction. and exhibits a high Young's modulus (e.g., over 700 ko/-Ju), but in the width direction perpendicular to this, it exhibits a high Young's modulus (e.g., 2 kg/-Ju).
j) and Young's modulus (for example, tookg/-) are both extremely strong. As a result, such polyester films are either not practical, or even if they are, this property is a major hindrance to practical use.

The present inventor has conducted repeated research on a method for obtaining a biaxially oriented polyester film that does not have such drawbacks from a polyester that has the property of forming optically anisotropic #-objects, and as a result, has arrived at the method of the present invention. did.

That is, in the present invention, when melting and forming a film from a polyester that has the property of forming an optically anisotropic melt, the polyester is extruded through a slit at a temperature higher than the temperature at which its melt viscosity reaches its minimum point to form a film. This is a method for producing a polyester film characterized by the following.

In the present invention, a polyester having the property of forming an optically anisotropic #molten material is a polymer having a melt state of 114 K, t'N, which has a property of allowing polarized light to pass through in an optical system equipped with a polarizer crossed at 90°. Say polyester.

Such polyesters include, for example, 1) terephthalic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid;
Dicarboxylic acid.

Symmetrical aromatic dicarboxylic acids such as trans-cyclohexane-1,4-2carboxylic acid or 1j-
phosphoric acid; methyl terephthalic acid.

Methoxyterephthal aI, Chrono-terephthalic acid, Bromoterephthalic acid, Diphenyl Able-2,2-dimethyl-4,4'-dicarboxylic acid.

Diphenoxyethane-2,2-dichloro-4゜4'-
The main acid component is a lower alkyl, lower alkoxy or halogen nucleus substituted product of the symmetrical aromatic dicarboxylic acid or alicyclic dicarboxylic acid such as dicarboxylic acid, trans-shifted hexane-1-meglu-1,4-dicarboxylic acid, etc. and hydroquinone, 4,4'-dioxydiphenyl, 4,4'-dioxydiphenyl ether, bis(
Symmetrical dioxyaromatic compounds such as 4-oxyphenooxy)ethane; chlorohydroquinone, poumhydroquinone.

Methylhydroquinone, ethylhydroquinone, No. 3
l-butylhydro-p-quinone, tertiary amylhydroquinone, phenylhydroquinone, 2,2'-dimethyl-4,
4'-dioxydiphenyl, 3,3'-diphthoxy-
Lower furkyl, lower alkoxy, aryl or halogen nucleus substituted products of symmetrical dioxyaromatic compounds such as 4,4'-dioquine diphenyl needle, bis(2-rep-4-oxyphenoxy)ethane, etc. Homopolyester or copolyester as the main diol component (
(hereinafter referred to as polyester I), 2) p-oxybenzoic acid, 4-oxydiphenyl-4'
-carboxylic acid, 3-chloro-4-oxybenzoic acid, 3-
Methoxy-4-oxybenzoic acid, 3-ethoxy-4
-oxybenzoic acid, 2-methyl-4-oxybenzoic acid,
Aromatic oxycarboxylic acids such as 3-methyl-4-oxybenzoic acid, 2-chloro-4-oxydiphenyl-4'-carboxylic acid and/or lower argyl, lower flukoxy or halogen-substituted derivatives thereof. Examples include copolyesters (hereinafter referred to as polyesters) containing as a main component.

Here, as acid components that can be copolymerized with polyester ■, in addition to oxycarionic acids which are the main components of polyester H, inphthal #, diphenyl ether = 3
．． 3'-dicarboxylic acid, diphenoxyethane-3,3
'-Dicarboxylic acid, naphthalene-1,6-dicarboxylic acid.

m-fang xybenzoic acid, 5-methylisophthalic acid, 5-chloroisophthalic acid, 4-methylinphthalic acid, 5-tertiary butyl isophthalic acid.

diphenyl ether-4,4'-dichloro-'s, 3
1-dicarboxylic acid, diphenyl-3,4'-trimethyl-
4,3'-dicarboxylic acid, dife/oxyethane-2,
2'-Syfurome-3,3'-dicarboxylic acid.

Naphthalene-2,7-diku-pru 1.6. - dicarboxylic acid, 4-ethoxy-3-oxybenzoic acid, carbonic acid, aromatic dicarboxylic acids such as cyclohexane-1,3-dicarboxylic acid, aromatic oxycarboxylic acids, or alicyclic dicarboxylic acids.

On the other hand, the acid component copolymerized with polyester (1) is the upper acid component or copolymerization component of polyester (1).
It is an acid component.

In addition, examples of diol components that can be copolymerized with polyester 1 include resorcinol, 3. :l'-dioxydiphenyl, 3
．． 3'-dioxydiphenyl ether, 1,6-siophyne sinaphthalene, bis(3-hydroxyphenoxy)ethane, 2°2-bis(4-hydroxyphenyl)purpane, 1. l-bis(4-hydroxyphenyl)cyclohexane, 4-chlorresorcin, 4-ethoxyresorcin, 4-bromoresorcin, 4,4'-diphthoxy-3,3'-dioxydiphenyl, 4,4'-dimethyl -3,3'-dioxydiphenyl, 4.4'-diphthoxy-3,3'-dioxydiphenyl ether, 2.4
'-dichloro, 3.3'-dioxydiphenyl ether, 2.5-dichloro-1,6-dihydroxynaphthalene, 2.2'-dibromo-3,3'-dioxydiphenooxyethane, etc. Examples include aromatic dioxy compounds, stiff lower alkyds, lower hexahalogen substituted compounds, etc.Next, the two-dimensional compound used in polyester UK copolymerization is polyester. The above-mentioned 5'-ol component is the upper diol component or copolymerization component of 1.

Specific examples of preferred polyesters in the present invention include (1) p-oxybenzoic acid and terephthalic acid, isophthalic acid, diphenoxyethane-4,4'-dicarboxylic acid,
Diphenyl ether-4,4'-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid*.

One or more selected from the group consisting of naphthalene-2,7-dicarboxylic acids, and hydroquinone, resorcinol, and phosphoric acid p-quinone.

Methyl hydroquinone, @3 static butyl hydroquinone 7,
One or two dioxyaromatic compounds selected from the group consisting of tertiary amylhydride q-quinone, 4゜4'-dioxydiphenyl and 4,4'-dioxydiphenyl ether.
Copolyester composed of esters with more than one species; (
2) Terephthalic acid, diphenyl ether-4,4'
- one or more selected from the group consisting of dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, and hydroquinone , trihydroquinone, methylhydroquinone, tertiary butylhydroquinone, tertiary amylhydroquinone, phenylhydroquinone, 4.4'-dioxine phenyl and 4.4
Homopolyester or copolyester composed of an ester with one or two selected from the group consisting of '-dioxydiphenyl ether; (31 terephthalic acid, inphthalic acid, chlorhydroquinone, 39th butylhydroquinone.

Examples include copolyesters composed of esters with one or more selected from the group consisting of amylhydride qquinone and phenylhydrquinone.

A particularly preferred polyester in the present invention is the formula (A
), (B1) and (C1) are polyesters composed of residues represented by (B1) and (C1).

The residue represented by formula (A) is a p-oxybenzoic acid residue, and the residue represented by formula (B) is a terephthalic acid or isophthalic acid residue, and the residue represented by formula (C) is a p-oxybenzoic acid residue. The residue is hydroquino/.

resorcinol, 4.4'-dioxydiphenyl, 3.3'
It is the residue of aromatic diols such as -dioxydiphenyl and '3,4'-dioxydiphenyl. In the present invention, particularly preferred specific examples of polyesters include: (1-1) Polyester containing p-oxybenzoic acid, inphthalic acid, and hydroquinone as main components; (1-2) p-oxybenzoic acid, terephthalic acid, and resorcinol; (l-)) p-oxybenzoic acid, inphthalic acid and 4
．． Polyester containing 4'-dioxydiphenyl as a main component; etc.

Among the polyesters of the present invention, the most preferred polyester is (1-1).

The polyester of the present invention can be produced by a conventionally known method. For example, 1) an aromatic dicarboxylic acid and/or an alicyclic dicarboxylic acid and a lower aliphatic ester of a dioxyaromatic compound (for example, acetic acid ester) are optionally combined with a lower aliphatic ester of an aromatic oxycarboxylic acid ( -) 7-aryl esters of aromatic dicarboxylic acids and/or alicyclic dicarboxylic acids (for example, phenyl esters, etc.)
and a dioxyaromatic compound, if necessary, together with a 7-aryl ester (for example, phenyl ester, etc.) and/or a diaryl carbonate (for example, diphenyl carbonate, etc.) of an aromatic oxycarboxylic acid.

In the present invention, polyesters practically composed of residues represented by the formulas (^), (B) and (C) are specifically the following formulas (p- human, xybenzoic acid and/or its derivatives, benzenedicarboxylic acid and/or its derivatives, and dioxybenzene and/or dioxydiphenyl and/or
Alternatively, it can be obtained by heating and polymerizing derivatives thereof.

In the above formula, FLI, Rs, and R are each independently selected from the group consisting of a hydrogen atom, a lower alkanoyl group having 7 or less carbon atoms, and a benzoyl group, and Rs, Rs, and R4 are hydrogen atoms, and carbon atoms 6 to +2 carbon atoms per gram. Aryl group and carbon #P 6
J! It is independently selected from the group consisting of lower alkyl groups under J.

The polyester of the present invention can be produced by a conventionally known method, but these raw materials are melt-polymerized (preferably under reduced pressure) at a polymerization temperature lower than 320° C. (preferably under reduced pressure), and then the obtained It is preferable to use a method in which a prepolymer is solid-phase polymerized.

By such a method, the apparent melt viscosity becomes s, oo at a slip rate of 100 eC' (film forming temperature).

A high polymerization degree polyester having a poise or more, preferably an io, ooo void or more, particularly preferably a so, ooo void or more is obtained. If the degree of polymerization of the polynisple is too low, the strength of the obtained film will not be sufficient, and it is not preferable because the film will become fibrillated when, for example, a desired film is produced by melt extrusion. Further, the polyester of the present invention is selected to have a softening point of 150 to 380°C, preferably 200 to 350°C.

In the present invention, the above-mentioned polyester is extruded into a film through a slit at a temperature μ higher than the temperature at which its melt viscosity reaches its minimum point.

When polyester, which has the property of forming an optically anisotropic melt, is amped by the conventional melting method, as mentioned above, molecular orientation occurs in the extrusion direction when passing through the die slit, and so A highly oriented film is obtained,
Even if you try to stretch the film, the stretched film will be uniform.
According to the study results of the present inventor, the reason for this is inferred as follows.

Generally, the melt viscosity of a polymer compound decreases as the temperature increases. However, the polyester of the present invention exhibits extremely unique properties; at relatively low temperatures, the KF+melt viscosity decreases as the temperature increases, but as the temperature increases further, the melt viscosity decreases to a marginal viscosity (minimum point). ) and then shows a characteristic that gradually increases. Conventionally, melt film formation has been performed at a temperature lower than the temperature at which the melt viscosity reaches its minimum point.

Therefore, it is surmised that the above-mentioned bribery point occurred.

According to the study results of the present inventor, melting &l! It has been found that the above-mentioned problems are significantly reduced or eliminated when the film is coated. Therefore, in the method of the present invention, it is necessary to perform melt extrusion at a temperature higher than the temperature at which the melt viscosity reaches its minimum point, and a film (original fabric) that is easily uniformly stretched and elastic by kneading can be obtained. Preferred melt extrusion temperatures are at least 20°C below the minimum temperature.

The temperature at which the melt viscosity reaches its minimum point varies depending on the composition and degree of polymerization of the polyester, but is generally around 330 to 400°C.

The spacing between the slits of the die on the side of the melting process can be selected as appropriate depending on the desired thickness of the film.
It is usually in the range of 0.01 to 10W, preferably 0.1 to 2W. The polyester immediately after being extruded from the slit is somewhat oriented in the direction in which the molten polyester was extruded (hereinafter referred to as the axial direction), but the orientation is sufficient as it is. occurs.

In the present invention, stretching in the machine axis direction and a direction at a negative angle thereto can be performed simultaneously, or biaxial stretching can be performed sequentially.

Conventionally known techniques can be applied to this stretching method. For example, 1) When the film coming out of the slit is pulled out by a pulling machine, it is first stretched in the direction of the machine axis, and then the film is drawn in the direction of the machine axis.
Stretch in the frl direction. it) The film coming out of the slit is taken up 411 (via a cooling drum or the like) and stretched along a side path so as to orient the molecules in the direction of the machine axis.

Next, hold both ends of the film with metal fittings and transfer to machine 111KI.
It is possible to stretch in the IL angle direction.

In addition, there is the inflation method, in which both ends of the film extruded from a slit are held between metal fittings, the metal fittings are moved in a direction perpendicular to the machine axis, and the distance between the metal fittings is extended in the machine axis direction, so that the film is stretched in the machine axis direction as well. For film forming/stretching force #, 4) such as 2@stretching method, the stretching ratio is usually 2x in the machine axis direction, preferably 3x,
-f=, particularly preferably selected in the range of 3 to 50 times. Further, the stretching ratio in the direction perpendicular to the machine axis direction is preferably 1.2 times or more, particularly preferably in the range of 1.5 to 10 times.

The polyester film obtained according to the present invention has a high Young's modulus and high strength, but also has poor film thickness uniformity and dimensional stability.

Furthermore, for the purpose of improving dimensional stability and mechanical strength, the film is heated in an appropriate temperature range below the softening point of polyester (for example, tSO ~ 300°C, preferably 250 ~ 300°C).
Heat treatment can be performed with At this time, the Young's modulus (9) strength, 2-dimensional stability, etc. can be improved by treating the polyester film under tension and/or relaxation for 0.01 to 10 minutes, or by treating the polyester film under polyester in-phase polymerization conditions. .

According to the method of the present invention, polyester having the property of forming an optically anisotropic melt is melted and made into a film that can be measured not only in the mechanical axis direction but also in the direction perpendicular to the mechanical axis. A uniform polyester film with good mechanical properties is obtained.

In addition, in the present invention, the softening point of polyester is determined by charging approximately II polyester into a Koka type flow tester equipped with a nozzle with a diameter of 1 stroke and a length of 5 m, under a pressure of xook kg/cd at a rate of 10°C per minute from room temperature. This is the temperature at which the polymer softens and starts flowing out from the nozzle, and also the sliding speed (γa) and apparent melt viscosity (η
A) is measured using the above-mentioned IWJ Jiku-type flow tester at the measurement temperature, and calculated using the following formula.

1 a-4Q / r"ηa-pr' / 81Q Furthermore, the Young's modulus and strength of the film are 5 m wide,
It is determined by applying a film with a sample length of 2.Ofi to an Instone tensile tester K and measuring the tensile speed at a rate of 100 inches per minute.

The present invention will be explained below with reference to Examples. In the examples, 1 part 1 means parts by weight.

Example 1 116 parts of phenyl p-oxybenzoate, 114 parts of diphenyl isophthalate and 42 parts of hydroquinone were reacted in the presence of 0.13 parts of stannous acetate at a temperature of 250 to 290°C and under normal pressure conditions for 2 hours. Then, the pressure of the reaction system was gradually reduced to 320°C, and the temperature was increased to 20°C.
Solution #I was combined for 20 minutes under reduced pressure of mHH.

The polyester obtained by this melt polymerization was crushed and
℃, 8 hours under 02 nod Hg conditions, further 270℃,
Solid phase polymerization was carried out for 7 hours under conditions of 0.211+llHg, and 3
A high degree of polymerization polyester having a melt viscosity of 70.000 voids at 50° C. and a sliding speed of to:, = was obtained. The temperature at which the melt viscosity of this highly polymerized polyester reached its minimum point was 380°C.

This high polymerization degree polyester was processed at a die temperature of 400°C to a width of 10 mm.
A basket, length 1 (lofi) is extruded through a T-die with slits at a speed of 0.3 fi per minute, and at the same time tension is applied to the film and the side layers are stretched 3 times in the machine axis direction and wound. I took it.

Next, clamp both ends of this film and
It was stretched 3 times in the direction perpendicular to the machine axis at °C. The mechanical performance and thickness unevenness of the obtained biaxially stretched film are shown in Table IK.
As shown.

Comparative Example 1 The same high degree of polymerization d°ligoster as obtained in Example 1 was extruded at a speed of 0.3 m/min through a T-die having a slit with a width of LOw+#100w1II at a die temperature of 360°C. At the same time, the film was stretched 3 times in the machine axis direction and wound up while being pulled off while applying tension to the film.

Next, clamp both ends of this film and
The mechanical properties and R-side unevenness of the obtained biaxially stretched film, which was stretched 3 times in the direction perpendicular to the machine axis at ℃, are as shown in Table 1.

Example 2 Melt polymerization was carried out in the same manner as in Example 1 except that 94 parts of phenyl p-oxybenzoate, 15 parts of diphenyl isophthalate, 42 parts of nohydrochlorine, and 0.12 parts of stannous vinegar were used. .2 2 hours at 250°C and 2 hours at 270°C under a vacuum of a+Hg.

Solid phase polymerization was carried out at 290°C for 2 hours and then at 310°C for 8 hours to obtain a highly polymerized polyester having a melt viscosity of 90,000 poise at 350°C and a -'t rate of 100 SeC.

The melt viscosity of this highly polymerized polyester reached a minimum point at a temperature of 360°C.

This high degree of polymerization polyester was heated to a cylinder temperature of 390°C with a width of 1. o B, T with a slit of length 100 cranes
-0.3 per minute faster than Thailand? While extruding at a speed of +1, the film was stretched 3 times in the machine axis direction while tension was applied and taken off, and the film was rolled up.

Next, clamp both ends of this film and
It was stretched 3 times in the direction perpendicular to the machine axis at °C. The mechanical performance and filling unevenness of the obtained biaxially stretched film are as shown in Table 1.

Table 1 Urn Shown as the difference in thickness (μ) between the thickest and thinnest parts of the film.

Claims (1)

[Claims] 1. When melt-forming a polyester that has the property of forming an optically anisotropic melt, the polyester/v is extruded through a slit at a temperature higher than the temperature at which its melt viscosity reaches its minimum point. , made! 2. A method for producing a polyester film in which the polyester has the following formula (A1. (B) and (
Polyester consisting of repeating units of C') -COO-+, ・・・・・・・・・(Al
The manufacturing method according to claim 1, characterized in that: 3. The manufacturing method according to claim 1rA, characterized in that the polyester is extruded through a slit at a temperature at least 20'C higher than the temperature at which its melt viscosity reaches its minimum point.