WO2020203389A1

WO2020203389A1 - Stretched film, laminate, cover window, and stretched film manufacturing method

Info

Publication number: WO2020203389A1
Application number: PCT/JP2020/012601
Authority: WO
Inventors: 篤南谷; 基白神; 英明武田
Original assignee: 株式会社クラレ
Priority date: 2019-03-29
Filing date: 2020-03-23
Publication date: 2020-10-08
Also published as: JPWO2020203389A1

Abstract

Provided is a stretched film having excellent heat resistance and transparency. This stretched film contains a semi-aromatic polyamide, wherein the semi-aromatic polyamide includes a dicarboxylate unit and a diamine unit, the dicarboxylate unit includes a naphthalene dicarboxylate unit, the diamine unit includes an aliphatic diamine unit having 4-12 carbon atoms, and the linear expansion coefficient of the stretched film at 50-150°C is -50×10^-6/°C to 50×10^-6/°C.

Description

Method for manufacturing stretched film, laminate, cover window, and stretched film

The present invention relates to a stretched film, a laminate, a cover window, and a method for manufacturing a stretched film. More specifically, a stretched film containing a semi-aromatic polyamide having a dicarboxylic acid unit containing a naphthalene dicarboxylic acid unit and a diamine unit containing an aliphatic diamine unit, and a laminate, a cover window, and a stretched film using the stretched film. Regarding the method.

The display used in all electronic devices such as TVs and smartphones is equipped with a cover window to protect the display. In general, the cover window has a structure in which a base material (hereinafter referred to as a substrate material) is provided with a layer (hereinafter referred to as a hard coat layer) for imparting adhesiveness and surface properties to an adhesive. It is a body. Since the cover window is installed on the surface of a display such as a liquid crystal display or an organic EL display, it has high transparency that allows light from the internal display to pass through, and also causes scratches due to contact with an object from the outside. To prevent it, it is necessary to have a certain surface hardness. For this reason, cover windows made of glass substrates are currently applied to various displays.

In recent years, flexible displays such as flexible displays have been attracting attention, and cover windows are also required to have flexibility that can follow the flexibility. However, since it is difficult to meet the demand for a cover window made of a glass substrate, the development of a material that is more flexible than glass without impairing the high transparency of glass is being promoted.

For example, a polyimide film is known as a candidate for the above material. However, in addition to the fact that the polyimide film is generally difficult to melt-mold, there is a problem that it is difficult to obtain a transparent film. Therefore, a transparent film that can be easily melt-molded is desired.

Acrylic film is a typical material having high transparency, flexibility, and melt moldability. Patent Document 1 shows that an acrylic film produced by a specific production method has a small dimensional change due to heat shrinkage and can be suitably used as an optical application film such as a polarizer protective film. However, when an acrylic film is used for the cover window, the hard coat layer is not cracked due to exposure to high temperature in the usage environment of the cover window, the coating process of the hard coat layer, etc. There is a problem that (called a crack) and warpage of the film occur. Further, since such a problem may be caused, a hard coat material having a high hardness cannot be applied, and there is a limit in improving the hardness of the cover window.

Patent Document 2 shows that a semi-aromatic polyamide resin obtained from a 2,6-naphthalenedicarboxylic acid unit and a 1,9-nonanediamine unit is excellent in mechanical properties, heat resistance, chemical resistance and the like. However, Patent Document 2 does not describe the physical properties of the film, and the behavior, physical properties, etc. when stretched are not clarified.

Patent Document 3 discloses a transparent polyamide film having a melting point of 270 ° C., a haze of less than 12%, and a light transmittance of at least 88%. However, since the polyamide film of Patent Document 3 is produced by using a polyamide resin in which at least two or more kinds of dicarboxylic acid units and two or more kinds of diamine units are copolymerized, the crystallinity of the film is low and the film is at high temperature. The change in the elasticity of the film is large, and both heat resistance and transparency are not achieved.

International Publication No. 2015/151466 Japanese Unexamined Patent Publication No. 9-12715 International Publication No. 2010/081871

In view of the above problems, the present invention is to obtain a film having high transparency and flexibility, and having heat resistance capable of preventing warpage and fine cracks of the film. Make it an issue.

As a result of diligent studies, the present inventors have obtained a stretched film containing a semi-aromatic polyamide having a dicarboxylic acid unit containing a naphthalene dicarboxylic acid unit and a diamine unit containing an aliphatic diamine unit at 50 ° C. to 150 ° C. It was found that a stretched film having a linear expansion rate of −50 × 10 ^-6 / ° C. or higher and 50 × ^10-6 / ° C. or lower can solve the above-mentioned problems, and further studies were carried out based on the findings to complete the present invention. ..
That is, the present invention is as follows.
[1] A stretched film containing a semi-aromatic polyamide.
The semi-aromatic polyamide contains a dicarboxylic acid unit and a diamine unit, the dicarboxylic acid unit contains a naphthalenedicarboxylic acid unit, and the diamine unit contains an aliphatic diamine unit having 4 to 12 carbon atoms.
A stretched film having a coefficient of linear expansion from 50 ° C. to 150 ° C. of -50 × 10 ^-6 / ° C. or higher and 50 × 10 ^-6 / ° C. or lower.
[2] When the tensile elastic modulus at 23 ° C. is E (23) and the tensile elastic modulus at 85 ° C. is E (85), (E (85) -E (23)) / E (23) × 100. The stretched film according to the above [1], wherein the absolute value of the elastic modulus change represented is 25% or less.
[3] The stretched film according to the above [1] or [2], wherein 60 mol% or more and 100 mol% or less of the naphthalene dicarboxylic acid unit is 2,6-naphthalene dicarboxylic acid.
[4] The stretched film according to any one of the above [1] to [3], wherein the aliphatic diamine unit having 4 to 12 carbon atoms contains an aliphatic diamine having 6 to 10 carbon atoms.
[5] The stretched film according to any one of the above [1] to [4], wherein the aliphatic diamine unit having 4 to 12 carbon atoms contains an aliphatic diamine having 8 to 10 carbon atoms.
[6] The stretched film according to any one of the above [1] to [5], wherein the aliphatic diamine unit contains 1,9-nonanediamine and 2-methyl-1,8-octanediamine.
[7] A laminate containing the stretched film according to any one of the above [1] to [6].
[8] A cover window comprising the stretched film according to any one of the above [1] to [6] or the laminate according to the above [7].
[9] The method for producing a stretched film according to any one of the above [1] to [6].
An unstretched film containing the semi-aromatic polyamide was prepared.
A method for producing a stretched film, wherein the unstretched film is subjected to a stretching treatment including at least a stretching step.
[10] A method for producing a stretched film containing a semi-aromatic polyamide.
The semi-aromatic polyamide contains a dicarboxylic acid unit and a diamine unit, the dicarboxylic acid unit contains a naphthalene dicarboxylic acid unit, and the diamine unit contains a diamine having 4 to 12 carbon atoms.
The stretching temperature is equal to or higher than the glass transition temperature of the semi-aromatic polyamide of −10 ° C. and lower than the recrystallization temperature of the unstretched film, the stretching rate is 100 to 5,000% / min, and the stretching ratio is 2 to 16 times. A method for producing a stretched film, wherein the heat fixing temperature is equal to or higher than the recrystallization temperature of the unstretched film.
[11] The method for producing a stretched film according to the above [9] or [10], wherein 60 mol% or more and 100 mol% or less of the naphthalene dicarboxylic acid unit is 2,6-naphthalene dicarboxylic acid.
[12] The method for producing a stretched film according to any one of the above [9] to [11], wherein the aliphatic diamine unit having 4 to 12 carbon atoms contains an aliphatic diamine having 6 to 10 carbon atoms.
[13] The method for producing a stretched film according to any one of the above [9] to [12], wherein the aliphatic diamine unit having 4 to 12 carbon atoms contains an aliphatic diamine having 8 to 10 carbon atoms.
[14] The method for producing a stretched film according to any one of the above [9] to [13], wherein the aliphatic diamine unit contains 1,9-nonanediamine and 2-methyl-1,8-octanediamine.

According to the present invention, it is possible to provide a stretched film having high transparency and flexibility and suppressing the occurrence of fine cracks and warpage, a laminate using the same, and a cover window. Further, it is possible to provide a method for producing a stretched film having high transparency and suppressing the occurrence of fine cracks and warpage of the film.

It is sectional drawing of the cover window.

Hereinafter, the present invention will be described in detail.
In the present specification, the preferred provisions can be arbitrarily adopted, and it can be said that a combination of preferable ones is more preferable.
In the present specification, the description of "XX to YY" means "XX or more and YY or less".
In the present specification, the lower limit value and the upper limit value described stepwise for a preferable numerical range (for example, a range such as content) can be independently combined. For example, from the description of "preferably 10 to 90, more preferably 30 to 60", the "favorable lower limit value (10)" and the "more preferable upper limit value (60)" are combined to obtain "10 to 60". You can also do it.
In the present specification, "-unit" (where "-" indicates a monomer) means "a constituent unit derived from", and for example, "dicarboxylic acid unit" means "derived from dicarboxylic acid". It means "constituent unit", and "diamine unit" means "constituent unit derived from diamine".
As used herein, the term "derived" with respect to each structural unit means that the monomer has undergone a structural change required for polymerization.
In the present specification, for example, "(meth) acrylic acid" means both "acrylic acid" and "methacrylic acid", and other similar terms are also used.
[Stretched film]
The stretched film according to the embodiment of the present invention is a stretched film containing a semi-aromatic polyamide, in which the semi-aromatic polyamide contains a dicarboxylic acid unit and a diamine unit, the dicarboxylic acid unit contains a naphthalene dicarboxylic acid unit, and the diamine unit. Contains an aliphatic diamine unit having 4 to 12 carbon atoms, and has a linear expansion coefficient of −50 × 10 ^-6 / ° C. or higher and 50 × ^10-6 / ° C. or lower at 50 ° C. to 150 ° C.
The physical properties of the stretched film will be described later, and first, each element constituting the stretched film will be described.

<Semi-aromatic polyamide>
The semi-aromatic polyamide used in the stretched film according to the embodiment of the present invention has a dicarboxylic acid unit and a diamine unit. The dicarboxylic acid unit contains a naphthalene dicarboxylic acid unit, and the diamine unit contains an aliphatic diamine unit having 4 to 12 carbon atoms.

(Dicarboxylic acid unit)
The dicarboxylic acid unit contains a naphthalene dicarboxylic acid unit, and preferably 40 mol% or more and 100 mol% or less is a naphthalene dicarboxylic acid unit. When the dicarboxylic acid unit contains a naphthalene carboxylic acid unit, it is advantageous to exhibit various physical property improving effects such as heat resistance. When the content of the naphthalene carboxylic acid unit in the dicarboxylic acid unit is 40 mol% or more, it becomes easy to exhibit various physical property improving effects such as heat resistance in the polyamide film.
From the viewpoint of heat resistance, transparency and the like, the content of the naphthalene carboxylic acid unit in the dicarboxylic acid unit is more preferably 60 mol% or more, further preferably 80 mol% or more, and further preferably 90 mol% or more. More preferably, it is particularly preferably 100 mol%.

Examples of the naphthalenedicarboxylic acid unit include 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, and 1 , 7-Naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid and other constituent units derived from naphthalenedicarboxylic acid. Be done. Only one type of these constituent units may be contained, or two or more types may be contained. Among the above naphthalene dicarboxylic acids, 2,6-naphthalene dicarboxylic acid is preferable from the viewpoint of expression of various physical properties such as heat resistance and reactivity with diamine.
From the same viewpoint as above, the content of the constituent unit derived from 2,6-naphthalenedicarboxylic acid in the naphthalene dicarboxylic acid unit is preferably 60 mol% or more, more preferably 80 mol% or more. , 90 mol% or more is more preferable, and the closer to 100 mol% (substantially 100 mol%) is preferable.

The dicarboxylic acid unit can include a structural unit derived from a dicarboxylic acid other than naphthalenedicarboxylic acid as long as the effect of the present invention is not impaired.
Examples of the other dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, undecandicarboxylic acid, dodecanedicarboxylic acid, dimethylmalonic acid, and , 2-Diethylsuccinic acid, 2,2-dimethylglutaric acid, 2-methyladipic acid, trimethyladiponic acid and other aliphatic dicarboxylic acids; 1,3-cyclopentanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1, Cyclic aliphatic dicarboxylic acids such as 4-cyclohexanedicarboxylic acid, cycloheptanedicarboxylic acid, cyclooctanedicarboxylic acid, cyclodecanedicarboxylic acid; terephthalic acid, isophthalic acid, diphenic acid, 4,4'-biphenyldicarboxylic acid, diphenylmethane-4, Examples thereof include aromatic dicarboxylic acids such as 4'-dicarboxylic acid and diphenylsulfon-4,4'-dicarboxylic acid. Only one type of structural unit derived from these other dicarboxylic acids may be contained, or two or more types may be contained.
The content of the constituent unit derived from the other dicarboxylic acid in the dicarboxylic acid unit is preferably 50 mol% or less, more preferably 30 mol% or less, still more preferably 20 mol% or less. It is particularly preferably 10 mol% or less.

(Diamine unit)
The diamine unit contains an aliphatic diamine unit having 4 to 12 carbon atoms, and preferably 40 mol% or more and 100 mol% or less is an aliphatic diamine unit having 4 to 12 carbon atoms. Since the diamine unit contains an aliphatic diamine unit having 4 to 12 carbon atoms, it is advantageous for exhibiting various physical property improving effects such as heat resistance. When the total content of the aliphatic diamine unit having 4 to 12 carbon atoms in the diamine unit is 40 mol% or more, it becomes easy to exhibit various physical property improving effects such as heat resistance in the polyamide.
From the viewpoint of heat resistance, transparency, flexibility, etc., the total content of the aliphatic diamine units having 4 to 12 carbon atoms in the diamine unit is more preferably 60 mol% or more, and more preferably 80 mol% or more. Is even more preferable, 90 mol% or more is even more preferable, and 100 mol% is particularly preferable.

Examples of the aliphatic diamine unit having 4 to 12 carbon atoms include 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexamethylenediamine, 1,7-heptandiamine, and 1,8-octanediamine. , 1,9-Nonandiamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine and other linear aliphatic diamines; 1-butyl-1,2- Etandiamine, 1,1-dimethyl-1,4-butanediamine, 1-ethyl-1,4-butanediamine, 1,2-dimethyl-1,4-butanediamine, 1,3-dimethyl-1,4- Butanediamine, 1,4-dimethyl-1,4-butanediamine, 2-methyl-1,3-propanediamine, 2-methyl-1,4-butanediamine, 2,3-dimethyl-1,4-butanediamine , 2-Methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,4-dimethyl-1,6-hexanediamine, 3 , 3-Dimethyl-1,6-hexanediamine, 2,2-dimethyl-1,6-hexanediamine, 2,4-diethyl-1,6-hexanediamine, 2,2,4-trimethyl-1,6- Hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2-ethyl-1,7-heptanediamine, 2-methyl-1,8-octanediamine, 3-methyl-1,8-octanediamine , 1,3-Dimethyl-1,8-octanediamine, 1,4-dimethyl-1,8-octanediamine, 2,4-dimethyl-1,8-octanediamine, 3,4-dimethyl-1,8- Octanediamine, 4,5-dimethyl-1,8-octanediamine, 2,2-dimethyl-1,8-octanediamine, 3,3-dimethyl-1,8-octanediamine, 4,4-dimethyl-1, Examples thereof include structural units derived from branched aliphatic diamines such as 8-octanediamine, 2-methyl-1,9-nonandiamine, and 5-methyl-1,9-nonandiamine.
Only one type of these constituent units may be contained, or two or more types may be contained. Among the above aliphatic diamine units, 1,9-nonanediamine, 1,10-decanediamine and 2-methyl-1,2, from the viewpoints that the effect of the present invention is more remarkable and the availability of raw materials is excellent. A structural unit derived from at least one diamine selected from the group consisting of 8-octanediamine is preferable, and 1,9-nonandiamine and 2-methyl-1,8-octanediamine are more preferably contained.

The diamine unit can include a structural unit derived from a diamine other than the aliphatic diamine having 4 to 12 carbon atoms as long as the effect of the present invention is not impaired. Examples of the other diamines include aromatic diamines and alicyclic diamines. Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4. '-Diaminodiphenyl ether and the like can be mentioned. Examples of the alicyclic diamine include cyclohexanediamine, methylcyclohexanediamine, isophoronediamine, norbornanedimethyldiamine, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane and the like. Only one type of structural unit derived from these other diamines may be contained, or two or more types may be contained. The content of the constituent units derived from the other diamines in the diamine unit is preferably 30 mol% or less, more preferably 20 mol% or less, and further preferably 10 mol% or less.

(Dicarboxylic acid unit and diamine unit)
The molar ratio [dicarboxylic acid unit / diamine unit] of the dicarboxylic acid unit to the diamine unit in the semi-aromatic polyamide is preferably 45/55 to 55/45. When the molar ratio of the dicarboxylic acid unit and the diamine unit is within the above range, the polymerization reaction proceeds well, and a polyamide having excellent moldability when forming a film can be easily obtained.
The molar ratio of the dicarboxylic acid unit and the diamine unit can be adjusted according to the blending ratio (molar ratio) of the raw material dicarboxylic acid and the raw material diamine.

The total ratio of the dicarboxylic acid unit and the diamine unit in the semi-aromatic polyamide (the ratio of the total number of moles of the dicarboxylic acid unit and the diamine unit to the number of moles of all the constituent units constituting the polyamide) shall be 70 mol% or more. It is preferably 80 mol% or more, more preferably 90 mol% or more, 95 mol% or more, and even 100 mol%. When the total ratio of the dicarboxylic acid unit and the diamine unit is in the above range, it becomes easy to obtain a polyamide having more excellent physical properties.

(Amino carboxylic acid unit)
The semi-aromatic polyamide may further contain an aminocarboxylic acid unit in addition to the dicarboxylic acid unit and the diamine unit.
Examples of the aminocarboxylic acid unit include lactams such as caprolactam and lauryllactam; and constituent units derived from aminocarboxylic acids such as 11-aminoundecanoic acid and 12-aminododecanoic acid. The content of the aminocarboxylic acid unit in the semi-aromatic polyamide is preferably 40 mol% or less, preferably 20 mol% or less, based on 100 mol% of the total of the dicarboxylic acid unit and the diamine unit constituting the semi-aromatic polyamide. Is more preferable.

(Polyvalent carboxylic acid unit)
The semi-aromatic polyamide is a structural unit derived from a trivalent or higher valent carboxylic acid such as trimellitic acid, trimesic acid, and pyromellitic acid, as long as the effect of the present invention is not impaired, and can be melt-molded. It can also be included.

(Terminal sealant unit)
The semi-aromatic polyamide may contain a structural unit (terminal encapsulant unit) derived from the end encapsulant.
The terminal encapsulant unit is preferably 1.0 mol% or more, more preferably 1.2 mol% or more, and 1.5 mol% or more with respect to 100 mol% of the diamine unit. Is more preferably 10 mol% or less, more preferably 7.5 mol% or less, still more preferably 6.5 mol% or less. When the content of the terminal encapsulant unit is within the above range, it becomes easy to obtain a polyamide having excellent film moldability. The content of the terminal encapsulant unit can be set within the above desired range by appropriately adjusting the amount of the end encapsulant when the polymerization raw material is charged. Considering that the monomer component volatilizes during polymerization, it is desirable to finely adjust the amount of the terminal encapsulant charged so that a desired amount of the terminal encapsulant unit is introduced into the obtained polyamide.
As a method for determining the content of the terminal encapsulant unit in the semi-aromatic polyamide, for example, as shown in JP-A-7-228690, the solution viscosity is measured, and this is combined with the number average molecular weight. A method of calculating the total amount of terminal groups from the relational expression and reducing the amount of amino groups and carboxyl groups obtained by titration from this, or using ¹ H-NMR, signals corresponding to each of the diamine unit and the terminal encapsulant unit. A method of obtaining the value based on the integrated value of is mentioned, and the latter is preferable.

As the terminal encapsulant, a monofunctional compound having reactivity with a terminal amino group or a terminal carboxyl group can be used. Specific examples thereof include monocarboxylic acids, acid anhydrides, monoisocyanates, monoacid halides, monoesters, monoalcohols and monoamines. From the viewpoint of reactivity and stability of the sealing terminal, a monocarboxylic acid is preferable as the terminal sealing agent for the terminal amino group, and a monoamine is preferable as the terminal sealing agent for the terminal carboxyl group. From the viewpoint of ease of handling, a monocarboxylic acid is more preferable as the terminal encapsulant.

The monocarboxylic acid used as the terminal encapsulant is not particularly limited as long as it has reactivity with an amino group. For example, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, capric acid, and laurin. Alicyclic monocarboxylic acids such as acids, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, isobutyric acid; alicyclic monocarboxylic acids such as cyclopentanecarboxylic acid and cyclohexanecarboxylic acid; benzoic acid, toluic acid, Aromatic monocarboxylic acids such as α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, phenylacetic acid; any mixture thereof and the like can be mentioned. Among these, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, etc., in terms of reactivity, stability of the sealing end, price, etc. , And at least one selected from the group consisting of benzoic acid is preferred.

The monoamine used as the terminal encapsulant is not particularly limited as long as it has reactivity with a carboxyl group. For example, methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine and stearyl are not particularly limited. Adipose monoamines such as amines, dimethylamines, diethylamines, dipropylamines and dibutylamines; alicyclic monoamines such as cyclohexylamines and dicyclohexylamines; aromatic monoamines such as aniline, toluidine, diphenylamines and naphthylamines; any mixture thereof and the like. Can be mentioned. Among these, at least one selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline from the viewpoints of reactivity, high boiling point, stability of sealing end, and price. Is preferable.

The semi-aromatic polyamide preferably has an intrinsic viscosity η _inh of 0.1 dl / g or more, preferably 0.4 dl / g or more, measured at a concentration of 0.2 g / dl and a temperature of 30 ° C. using concentrated sulfuric acid as a solvent. More preferably, it is more preferably 0.6 dl / g or more, particularly preferably 0.8 dl / g or more, and more preferably 3.0 dl / g or less, and 2.0 dl / g or less. It is more preferably less than or equal to 1.8 dl / g or less. When the intrinsic viscosity η _{inh of the} polyamide is within the above range, it becomes easier to improve various physical properties such as moldability and heat resistance of the film. The intrinsic viscosity η _inh is the flow time of the solvent (concentrated sulfuric acid) t ₀ (sec), the flow time of the sample solution t ₁ (sec), and the sample concentration c (g / dl) in the sample solution (that is, 0.2 g / dl). ), It can be obtained by the relational expression of η _inh = [ln (t ₁ / t ₀ )] / c.

The melting point (Tm) of the semi-aromatic polyamide is not particularly limited and can be, for example, 260 ° C. or higher and 270 ° C. or higher. However, since the effect of the present invention is more remarkable, the temperature is 280 ° C. or higher. It is preferable to have. The upper limit of the melting point of the semi-aromatic polyamide is not particularly limited, but it is preferably 330 ° C. or lower in consideration of moldability and the like. The melting point of the semi-aromatic polyamide can be determined as the peak temperature of the melting peak that appears when the temperature is raised at a rate of 10 ° C./min using a differential scanning calorimetry (DSC) device, and more specifically, it will be described later. It can be obtained by the method described in the example.

The glass transition temperature (Tg) of the semi-aromatic polyamide is not particularly limited and can be, for example, 100 ° C. or higher and 110 ° C. or higher. However, since the effect of the present invention is more pronounced, 125 ° C. The above is preferable. The upper limit of the glass transition temperature of the semi-aromatic polyamide is not particularly limited, but it is preferably 180 ° C. or lower in consideration of moldability and the like. The glass transition temperature of the semi-aromatic polyamide can be determined as the temperature of the inflection point that appears when the temperature is raised at a rate of 20 ° C./min using a differential scanning calorimetry (DSC) device, more specifically described later. It can be obtained by the method described in the examples.

(Manufacturing method of semi-aromatic polyamide)
The semi-aromatic polyamide can be produced by any method known as a method for producing a crystalline polyamide, for example, a melt polymerization method, a solid phase polymerization method, which uses a dicarboxylic acid and a diamine as raw materials. It can be produced by a method such as a melt extrusion polymerization method. Among these, the solid phase polymerization method is preferable from the viewpoint that thermal deterioration during polymerization can be suppressed more satisfactorily.
When, for example, 2-methyl-1,8-octanediamine and 1,9-nonanediamine are used as the aliphatic diamine having 4 to 12 carbon atoms, these can be produced by known methods. Examples of known methods include a method of distilling a crude diamine reaction solution obtained by performing a reductive amination reaction using dialdehyde as a starting material. Further, 2-methyl-1,8-octanediamine and 1,9-nonanediamine can be obtained by fractional distillation of the above-mentioned crude diamine reaction solution.

The semi-aromatic polyamide is, for example, first added with a diamine, a dicarboxylic acid, and if necessary, a catalyst and an end-capping agent in a batch to produce a nylon salt, and then heat-polymerized at a temperature of 200 to 250 ° C. It can be produced by solid-phase polymerization or polymerization using a melt extruder. When the final stage of polymerization is carried out by solid phase polymerization, it is preferably carried out under reduced pressure or under an inert gas flow, and when the polymerization temperature is in the range of 200 to 280 ° C., the polymerization rate is high and the productivity is excellent. Coloring and gelation can be effectively suppressed. When the final stage of polymerization is carried out by a melt extruder, the polymerization temperature is preferably 370 ° C. or lower, and when polymerization is carried out under such conditions, semi-aromatic polyamide with almost no decomposition and little deterioration can be easily obtained.

Examples of the catalyst that can be used in producing the semi-aromatic polyamide include phosphoric acid, phosphorous acid, hypophosphorous acid, and salts or esters thereof. Examples of the above salts or esters include phosphoric acid, phosphite or hypophosphoric acid, potassium, sodium, magnesium, vanadium, calcium, zinc, cobalt, manganese, tin, tungsten, germanium, titanium, antimony and the like. Salt with metal; ammonium salt of phosphoric acid, phosphite or hypophosphoric acid; ethyl ester of phosphoric acid, phosphite or hypophosphoric acid, isopropyl ester, butyl ester, hexyl ester, isodecyl ester, octadecyl ester , Decyl ester, stearyl ester, phenyl ester and the like.
The amount of the catalyst used is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and 1.0% by mass or less with respect to 100% by mass of the total mass of the raw materials. It is preferably 0.5% by mass or less, and more preferably 0.5% by mass or less. When the amount of the catalyst used is equal to or higher than the above lower limit, the polymerization proceeds satisfactorily. If it is not more than the above upper limit, impurities derived from the catalyst are less likely to occur, and for example, when a polyamide or a polyamide composition containing the same is made into a film, it becomes easy to prevent defects due to the impurities.

(Polyamide composition)
In order to further improve various physical properties of the film finally obtained, the semi-aromatic polyamide may be blended with other components as long as the effects of the present invention are not impaired to form a polyamide composition. A stretched film containing a semi-aromatic polyamide can be obtained by performing a stretching treatment described later using a semi-aromatic polyamide or polyamide composition.
Other components include, for example, pigments and dyes such as carbon black, niglosin, titanium oxide; ultraviolet absorbers; light stabilizers such as hindered amines; organics such as hindered phenols, thios, phosphorus and amines. Antioxidants; Inorganic antioxidants such as a combination of copper halides such as copper iodide and copper bromide and alkali metals halides such as potassium iodide and potassium bromide; antistatic agents; fluorescent whitening agents; Brominated polymers such as brominated polystyrene, flame retardant aids such as antimony oxide; lubricants such as aliphatic amides, fatty acid esters, fatty acid metal salts, polyethylene wax, polypropylene wax, silica; polyphenylene sulfide, liquid crystal polymers, polyethylene, polystyrene, Other polymers such as polyester, aliphatic polyamide, semi-aromatic polyamide, polyphenylene oxide, polyolefin-based elastomer, styrene-based elastomer, polyester elastomer, polyamide elastomer; organic and inorganic powders or various fibrous fillers, etc. Be done. These may contain only one kind, or may contain two or more kinds. The aliphatic polyamide or semi-aromatic polyamide as other components contained in the polyamide composition has a chemical structure different from that of the semi-aromatic polyamide used in the stretched film according to the embodiment.
The content of the semi-aromatic polyamide in the polyamide composition is, for example, 20% by mass or more, 50% by mass or more, 70% by mass or more, 85% by mass or more, 95% by mass or more, based on the total mass of the polyamide composition. It can be 99% by mass or more.
The content of the above other components in the polyamide composition is not particularly limited and can be appropriately adjusted according to the type of the other components and the use of the polyamide composition. For example, with respect to the total mass of the polyamide composition. Therefore, it can be 80% by mass or less, 50% by mass or less, 30% by mass or less, 15% by mass or less, 5% by mass or less, 1% by mass or less, and the like.

Examples of the aliphatic polyamide and semi-aromatic polyamide blended as other components include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), and the like. Polytetramethylene sebacamide (nylon 410), polypentamethylene adipamide (nylon 56), polypentamethylene sebacamide (nylon 510), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 610) Nylon 612), Polydecamethylene adipamide (Nylon 106), Polydecamethylene sebacamide (Nylon 1010), Polydecamethylene dodecamide (Nylon 1012), Polyundecaneamide (Nylon 11), Polydodecaneamide (Nylon 12) ), Polycaproamide / Polyhexamethylene adipamide copolymer (Nylon 6/66), Polytetramethylene terephthalamide (Nylon 4T), Polyhexamethylene terephthalamide (Nylon 6T), Polytetramethylene terephthalamide / Polyhexamethylene terephthalamide Amide (nylon 6T / 4T), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polytetramethylene terephthalamide / polytetramethylene adipamide (nylon 66 / 6T / 4T / 46), polyhexamethylene terephthalamide / Polycaproamide copolymer (nylon 6T / 6), polyhexamethylene terephthalamide / polyundecaneamide copolymer (nylon 6T / 11), polyhexamethylene terephthalamide / polydodecaneamide copolymer (nylon 6T / 12), polyhexamethylene adipa Mid / polyhexamethylene terephthalamide copolymer (nylon 66 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I), polyhexamethylene adipamide / polyhexamethylene isophthalamide / polycapro Amide copolymer (nylon 66 / 6I / 6), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T / 6I), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide Copolymer (Nylon 6T / 6I), Polyhexamethylene terephthalamide / Poly (2-methylpentamethylene) Tele Phthalamide copolymer (nylon 6T / M5T), polynonamethylene terephthalamide (nylon 9T), poly (2-methyloctamethylene) terephthalamide (nylon M8T), polynonamethylene terephthalamide / poly (2-methyloctamethylene) terephthal Amide copolymer (nylon 9T / M8T), polydecamethylene terephthalamide (nylon 10T), polyundecamethylene terephthalamide (nylon 11T), polydodecamethylene terephthalamide (nylon 12T), polypentamethylene terephthalamide / polydecamethylene terephthalamide Amide copolymer (nylon 5T / 10T), polydecamethylene terephthalamide / polyhexamethylene dodecaneamide copolymer (nylon 10T / 612), polydecamethylene terephthalamide / polyhexamethylene terephthalamide (nylon 10T / 6T), polydecamethylene terephthalamide Amide / polyhexamethylene adipamide copolymer (nylon 10T / 66), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polydecamethylene terephthalamide / polydecamethylene methylene adipamide (nylon 66 / 6T / 10T / 106), Polydecamethylene terephthalamide / polyundecaneamide copolymer (nylon 10T / 11), polyhexamethylenecyclohexanecarbamide (nylon 6C), polyhexamethylenecyclohexanecarbamide / poly (2-methylpentamethylene) cyclohexanecarbamide copolymer (Nylon 6C / M5C), Polynonamethylene Cyclohexane Carboamide (Nylon 9C), Poly (2-Methyl Octamethylene) Cyclohexane Carbamide (Nylon M8C), Polynonamethylene Cyclohexane Carbamide / Poly (2-Methyl Octamethylene) Cyclohexane Examples thereof include carboamide copolymers (nylon 9C / M8C) and copolymers thereof.

Examples of the method of adding the above-mentioned various additives include a method of adding the semi-aromatic polyamide at the time of polymerization, a method of dry blending the semi-aromatic polyamide with melt kneading, and a method of adding the semi-aromatic polyamide at the time of film molding.

(Method for producing polyamide composition)
The method for producing the polyamide composition is not particularly limited, and a method capable of uniformly mixing the semi-aromatic polyamide and the above other components can be preferably adopted. For mixing, a method of melt-kneading using a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer or the like is usually preferably adopted. The melt-kneading conditions are not particularly limited, and examples thereof include a method of melt-kneading for about 1 to 30 minutes in a temperature range of about 10 to 50 ° C. higher than the melting point of the semi-aromatic polyamide.

<Physical properties of stretched film>
The stretched film according to the embodiment of the present invention has a linear expansion coefficient of −50 × ^10-6 / ° C. or higher and 50 × ^10-6 / ° C. or lower calculated from the amount of dimensional change in the temperature range of 50 ° C. to 150 ° C. Preferably -40 × 10-6 / ° C. or higher 40 × 10-6 / ° C. or less, more preferably -30 × ^{10 -6} / ℃ least 30 × ^{10 -6} / ℃ less, more preferably -20 × ^{10 -6} / ° C or higher and 20 × ^10-6 / ° C or lower. When the coefficient of linear expansion of the stretched film is within the relevant range, the film does not warp and fine cracks do not occur due to the heat treatment in the process of applying the hard coat layer to the film, so that a high quality cover window can be obtained. Can be done. The coefficient of linear expansion can be obtained using a thermomechanical analyzer, and specifically, can be obtained by the method described later in the examples.
A stretched film having such physical properties is a semi-aromatic polyamide containing a dicarboxylic acid unit containing a naphthalene dicarboxylic acid unit and a diamine unit containing a diamine having 4 to 12 carbon atoms, or a polyamide composition containing the same. It can be produced by subjecting the raw fabric containing the film to a stretching treatment including a stretching step and an immobilization step. In particular, it is advantageous to perform a stretching treatment having a stretching step under specific conditions and a fixing step under specific conditions, which will be described later, on the raw film to obtain a stretched film having the above physical properties.

The shrinkage start temperature of the stretched film when the temperature is raised at 10 ° C./min is preferably 125 ° C. or higher, more preferably 130 ° C. or higher. When the shrinkage start temperature of the stretched film is within such a range, the film does not warp and fine cracks do not occur due to the heat treatment in the process of applying the hard coat layer to the film, so that a high quality cover window can be obtained. .. The shrinkage start temperature can be determined using a thermomechanical analyzer, and specifically, can be determined by the method described later in the examples.

The haze of the stretched film is preferably 10% or less, more preferably 7.0% or less, and even more preferably 5.0% or less. If the haze of the stretched film exceeds 10%, the amount of light transmitted from the light source when the cover window is used tends to be insufficient. The haze of the stretched film can be obtained in accordance with JIS K 7136 (2000), and specifically, can be obtained by the method described later in the examples.

Using the tensile elastic modulus E (23) at 23 ° C. and the tensile elastic modulus E (85) at 85 ° C. of the stretched film, the absolute value of the elastic modulus change represented by the following formula (1) is 25% or less. It is preferably 20% or less, more preferably 15% or less.
Modulus change (%) = (E (85) -E (23)) / E (23) x 100 ... Equation (1)
When the change in elastic modulus is within the range, the film is less likely to warp due to the heat treatment in the process of applying the hard coat layer to the film, and fine cracks are less likely to occur, so that it is easy to obtain a high-quality cover window. .. The tensile elastic modulus of the stretched film can be obtained by a tensile test, and specifically, can be obtained by the method described later in the examples.
When the value calculated by the equation (1) is negative, it means that the tensile elastic modulus at high temperature is smaller than the tensile elastic modulus at normal temperature.

The thickness of the stretched film is preferably 5 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 80 μm from the viewpoint of cost and surface hardness.

[Manufacturing method of stretched film]
The stretched film according to the embodiment of the present invention is stretched in at least one of the longitudinal direction and the width direction of the raw fabric film with respect to an unstretched film containing a semi-aromatic polyamide (hereinafter referred to as "raw fabric film"). It is produced by a method of performing a stretching process including a stretching step.

(Manufacturing method of raw film)
The method for producing the raw film is not particularly limited, and a semi-aromatic polyamide or a polyamide composition containing the same may be molded by a conventionally known method. As the molding method, for example, a melt extrusion method is preferably mentioned. The melt extrusion method is not particularly limited, and can be carried out by a melt extrusion method known in the art, and for example, a T-die method or an inflation method can be used. At this time, the extrusion temperature is preferably Tm + 10 ° C. or higher and 370 ° C. or lower for the semi-aromatic polyamide. If the extrusion temperature is Tm + 10 ° C. or higher, it becomes easy to avoid an increase in viscosity and the extrusion cannot be performed, and if the extrusion temperature is 370 ° C. or lower, the semi-aromatic polyamide is difficult to decompose. The thickness of the raw film is usually 1 to 500 μm, preferably 5 to 200 μm.

When the raw film is molded by the T-die method, the raw film extruded into a film can be obtained by connecting the T-die to the tip of a known single-screw extruder or twin-screw extruder.

The extruder preferably has one or more open vents. By using such an extruder, decomposition products and volatile components can be sucked from the open vent portion, and the quality of the obtained composition can be improved. Also, the extruder preferably has a polymer filter to remove foreign matter. Examples of the structure of the polymer filter include a leaf disc type and a candle type. Further, the extruder preferably has a gear pump to stabilize the discharge rate of the composition. A known gear pump can be used. When the extruder has an open vent portion, a gear pump and a polymer filter, it is preferable to connect in the order of extruder-gear pump-polymer filter-die from the viewpoint of reducing foreign matter and suppressing vent-up. Further, in order to prevent deterioration of the resin composition in the extruder, it is preferable to mold the resin composition while passing nitrogen through the extruder.

As an embodiment for producing a raw film, an extruded film-like molten resin is picked up between a mirror roll or a mirror belt and pressed from the viewpoint of ensuring the surface smoothness and thickness uniformity of the raw film. Is preferable. The mirror surface roll or the mirror surface belt is preferably made of metal. The mirror surface roll is more preferably a combination of a metal rigid body roll and a metal elastic roll. The linear pressure between the mirror surface rolls or the mirror surface belts is preferably 10 N / mm or more, more preferably 30 N / mm or more, from the viewpoint of surface smoothness. Usually, polyamide has a high crystallization rate and crystals easily grow. Therefore, from the viewpoint of suppressing crystal growth and facilitating stretching, it is preferable to quench the polyamide to Tg or less of the semi-aromatic polyamide. On the other hand, from the viewpoint of preventing the film from being wrinkled and deteriorating the appearance of the film and the stretchability, it is preferable to prevent the cooling rate from becoming excessively high. That is, it is preferable to control the cooling temperature within a certain range. Therefore, the surface temperature of the mirror surface roll or the mirror surface belt is preferably Tg-10 ° C. or lower and Tg-75 ° C. or higher of the semi-aromatic polyamide from the viewpoint of surface smoothness, haze, appearance and the like, and more preferably Tg-. It is 20 ° C. or lower and Tg-75 ° C. or higher.

Further, as another embodiment for producing the raw film, there is a method of not pinching. Specifically, from the viewpoint of surface smoothness and thickness uniformity of the film, it is preferable that the extruded film-like molten resin is brought into contact with and adheres to the mirror surface roll by an adhesion assisting device to be cooled and solidified. Examples of the close contact assisting device include an electrostatic close contact device, an air knife, an air chamber, a vacuum chamber, and the like. Edge pinning and wire pinning may be used together. Of these, from the viewpoint of manufacturing stability, it is preferable to use an electrostatic contact device as the contact assist device.

When edge pinning and wire pinning are used together as a close contact assisting device, it is preferable to arrange the edge pinning and wire pinning in this order from the upstream side. Further, the wire pinning is more preferably arranged on the downstream side including the position where the temperature of the molten resin on the mirror surface roll becomes the glass transition temperature, and on the upstream side from the position where the molten resin is peeled off from the mirror surface roll.

The raw film manufacturing process and the stretching process may be performed continuously or discontinuously.

(Stretching treatment of raw film)
The stretched film according to the embodiment of the present invention contains a semi-aromatic polyamide containing a dicarboxylic acid unit containing a naphthalene dicarboxylic acid unit and a diamine unit containing a diamine having 4 to 12 carbon atoms, or a polyamide composition containing the same. Manufactured by stretching an anti-film.
The stretching treatment of the raw film includes a stretching step of stretching the raw film to a predetermined magnification at a predetermined temperature and a predetermined speed, and a heat fixing step of heat-fixing the stretched film at a predetermined temperature. The heat resistance of the film can be improved by subjecting the raw film to a stretching treatment.
The stretching treatment includes a stretching step of stretching the film, and preferably further includes a preheating step performed prior to the stretching step. In the stretching step, for example, a sequential biaxial stretching method, a simultaneous biaxial stretching method, a tubular method and the like can be used. Above all, the simultaneous biaxial stretching method is most suitable because the film thickness accuracy is good and the physical properties in the film width direction are uniform. In the stretching treatment of the raw film, it is preferable to carry out the preheating step, the stretching step, and the heat fixing step in this order, and the relaxation step may be carried out after the heat fixing step. The semi-aromatic polyamide containing the dicarboxylic acid unit and the diamine unit having the above-mentioned chemical structure and blending ratio, or the raw fabric film containing the polyamide composition containing the above-mentioned semi-aromatic polyamide is subjected to a stretching treatment. A stretched film containing a group polyamide is obtained.

(Preheating process)
In the preheating step, the temperature of the raw fabric film is preferably Tg-10 ° C. or higher for the semi-aromatic polyamide and lower than the recrystallization temperature of the raw fabric film, and Tg or higher for the semi-aromatic polyamide and the raw fabric film. It is more preferable that the temperature is below the recrystallization temperature. When the temperature of the raw film in the preheating step is within the relevant range, breakage is less likely to occur in the stretching step during the production of the stretched film, productivity is easily improved, and heat resistance is easily improved. The recrystallization temperature of the raw film can be determined as the peak temperature of the exothermic peak that appears when the temperature is raised at a rate of 10 ° C./min using a differential scanning calorimetry (DSC) device. It can be obtained by the method described in the example.

The recrystallization temperature of the raw film is preferably 150 to 200 ° C, more preferably 160 to 180 ° C. When the recrystallization temperature of the raw film is within the above range, the preheating temperature, the heat fixing temperature, etc. do not become too high, so that deterioration due to oxidation is unlikely to occur, and a necessary difference between Tg and the recrystallization temperature. Is ensured, and it becomes easy to avoid the difficulty in stretching the raw film.
The recrystallization temperature of the raw film can be within the above numerical range, for example, by increasing the content of 2,6-naphthalenedicarboxylic acid as an acid component, preferably approaching 100%.

(Stretching process)
In the stretching step, the temperature of the raw film (stretching temperature) is set to Tg-10 ° C. or higher of the semi-aromatic polyamide and lower than the recrystallization temperature of the raw film. The stretching temperature is preferably Tg or more of the semi-aromatic polyamide and not more than the recrystallization temperature of the raw film. When the temperature of the raw film in the stretching step is within such a range, breakage is less likely to occur in the stretching step, productivity is easily improved, and heat resistance is easily improved.

In the stretching step, the stretching ratio of the raw film is 2.0 to 16 times, preferably 2.0 to 10 times, and more preferably 2.5 to 6.0 times. When the draw ratio is 2.0 times or more, deterioration of haze can be suppressed. Further, when the draw ratio is 16 times or less, particularly 10 times or less, and further 6.0 times or less, breakage is less likely to occur in the stretching step during the production of the stretched film, and the productivity is improved. The stretch ratio means the ratio of the area of the film after stretching to the area of the film before stretching.

In the stretching step, the stretching speed of the raw film is 100 to 5,000% / min, preferably 300 to 2,000% / min. When the stretching speed is within such a range, breakage is less likely to occur in the stretching step during the production of the stretched film, and the productivity can be easily improved.

In the heat fixing step, the temperature of the raw fabric film is equal to or higher than the recrystallization temperature of the raw fabric film, preferably the recrystallization temperature of the raw fabric film + 40 ° C. or higher, and more preferably the recrystallization temperature of the raw fabric film + 60 ° C. That is all. When the temperature of the raw film in the heat fixing step is within the relevant range, the change in elastic modulus between room temperature and high temperature is small, and the heat resistance is improved.

Using a semi-aromatic polyamide containing a dicarboxylic acid unit containing a naphthalenedicarboxylic acid unit and a diamine unit containing a diamine having 4 to 12 carbon atoms, or a raw fabric film containing a polyamide composition containing the same, the stretching temperature is semi-aromatic. The glass transition temperature of the group polyamide is -10 ° C or higher and the recrystallization temperature of the raw fabric film or lower, the stretching speed is 100 to 5,000% / min, the stretching ratio is 2 to 16 times, and the heat fixing temperature is set. By performing the stretching treatment at a temperature equal to or higher than the recrystallization temperature of the raw film, a stretched film having the above-mentioned physical properties can be obtained.

The stretching process may have a relaxation step after the heat fixing step. The relaxation rate of the film in the relaxation step is preferably 1 to 10%, more preferably 1 to 7%. By performing the relaxation treatment, it becomes easy to impart sufficient strength to the stretched film.

In order to improve the adhesiveness of the film surface, the stretched film is subjected to activation treatments such as corona treatment, plasma treatment, glow discharge treatment, acid treatment, flame treatment, ultraviolet irradiation treatment, electron beam irradiation treatment, and ozone treatment. May be given.

[Laminate and cover window]
A laminated body can be formed by providing the stretched film with another layer such as a hard coat layer.
FIG. 1 is a schematic cross-sectional view of a cover window according to an embodiment of a laminated body. As shown in FIG. 1, the cover window 3 has the above-mentioned stretched film 1 and the hard coat layer 2 provided on the stretched film 1.
As described above, the stretched film according to the present embodiment has transparency and heat resistance, and warpage and cracks are unlikely to occur even when the laminated film is formed. Therefore, the layer to be laminated on the stretched film can be selected from many options, and for example, a hard coat layer having high hardness can be imparted. Therefore, by forming a laminate provided with a high-hardness hard coat layer, for example, a cover window having high hardness that is strong against scratches caused by external objects can be obtained, which is widely used as a protective member for displays. It is possible.

(Hard coat layer)
A hard coat layer can be applied to the stretched film for the purpose of improving the surface hardness (pencil hardness, scratch resistance).

The material used for the hard coat layer that can be applied to the stretched film is not particularly limited, and is an acrylic resin that is cured by irradiating with ultraviolet rays (hereinafter referred to as "UV") or electron beams (hereinafter referred to as "EB"). Such as ionizing radiation curable resin; thermosetting resin such as epoxy resin and silicone resin which are cured by applying heat; inorganic fine particles such as silica particles which are coated on the film surface by coating or vapor deposition of a solvent. .. Among them, it is preferable to use a photocurable resin capable of highly improving the surface hardness.

The ionizing radiation curable resin can be appropriately selected from, for example, urethane acrylate-based resin, polyester acrylate-based resin, and the like. A preferred ionizing radiation curable resin is one consisting of a UV or EB curable polyfunctional acrylate having two or more (meth) acryloyl groups in the molecule. Specific examples of UV or EB curable polyfunctional acrylates having two or more (meth) acryloyl groups in the molecule include neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and the like. Polyacrylate polyacrylates such as trimethylolpropantri (meth) acrylate, ditrimethylolpropanetetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, bisphenol A Diacrylate of diglycidyl ether, diacrylate of neopentyl glycol diglycidyl ether, epoxy (meth) acrylate such as di (meth) acrylate of 1,6-hexanediol diglycidyl ether, polyhydric alcohol and polyvalent carboxylic acid and / Alternatively, urethane (meth) acrylate obtained by reacting polyester (meth) acrylate, polyhydric alcohol, polyvalent isocyanate, and hydroxyl group-containing (meth) acrylate, which can be obtained by esterifying the anhydride and acrylic acid. , Polysiloxane Poly (meth) acrylate and the like. In addition, you may use a mixture of 3 or more kinds of polyfunctional acrylates.

The coating thickness of the hard coat layer is not particularly limited, but is preferably in the range of, for example, 1 to 100 μm. If the coating thickness is 1 μm or more, the required hardness can be easily obtained. Further, when the coating film thickness is 100 μm or less, good extensibility can be easily obtained in the film after the coating film.

The coating method of the hard coat layer is not particularly limited, but it is easy to adjust the coating thickness such as gravure coating, microgravure coating, fountain bar coating, slide die coating, slot die coating, etc. Coating is possible by the method.

It is desirable that the stretched film according to the embodiment of the present invention does not warp or generate fine cracks in the step of applying the hard coat layer. As described above, a stretched film in which warpage and cracks are suppressed can be obtained by performing a stretching treatment under specific stretching conditions using a raw film containing a specific semi-aromatic polyamide. Warpage and fine cracks in the film can be discriminated by visually inspecting the film after coating, and specifically, can be discriminated by the method described later in the examples.

[Use]
The use of the stretched film is not particularly limited, and is an electrically insulating material for motors, transformers, cables, etc .; a dielectric material for capacitors, etc.; an electronic parts packaging material for semiconductor packages, etc.; a pharmaceutical packaging material; a retort food, etc. Food packaging materials; display cover windows, solar cell substrates, liquid crystal plates, conductive films, protective plates for display equipment, etc .; LED mounting substrates, flexible printed substrates, flexible flat cables, and other electronic substrate materials; FPC coverlay films, Heat-resistant adhesive tapes such as heat-resistant masking tapes and industrial process tapes; heat-resistant bar code labels; heat-resistant reflectors; various release films; heat-resistant adhesive base films; photographic films; molding materials; agricultural materials; medical materials; civil engineering , Building materials; Filter films, etc .; Can be used alone as films for household and industrial materials, or as a laminated body in which other layers such as a hard coat layer are laminated. In particular, it can be suitably used for a cover window for a display from the viewpoint of heat resistance and transparency.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The physical properties of the materials used in the examples and comparative examples were measured, and the physical properties of the films in the examples and comparative examples were measured and evaluated according to the methods shown below.

Melting point and glass transition temperature of semi-aromatic polyamide The melting point (Tm) and glass transition temperature (Tg) of semi-aromatic polyamide used in Examples and Comparative Examples are the differential scanning calorimetry device "DSC7020" manufactured by Hitachi High-Tech Science Co., Ltd. Was measured using.
The melting point was measured according to ISO11357-3 (2011 2nd edition). Specifically, the sample is heated from 30 ° C. to 340 ° C. at a rate of 10 ° C./min under a nitrogen atmosphere and held at 340 ° C. for 5 minutes to completely melt the sample, and then 10 ° C./min. It was cooled to 50 ° C. at a rate and held at 50 ° C. for 5 minutes. The peak temperature of the melting peak that appears when the temperature is raised to 340 ° C at a rate of 10 ° C / min again is defined as the melting point (° C), and when there are multiple melting peaks, the peak temperature of the melting peak on the highest temperature side is defined as the melting point (° C). did.
The glass transition temperature (° C.) was measured in accordance with ISO11357-2 (2013 2nd edition). Specifically, the sample is heated from 30 ° C. to 340 ° C. at a rate of 20 ° C./min under a nitrogen atmosphere and held at 340 ° C. for 5 minutes to completely melt the sample, and then 20 ° C./min. It was cooled to 50 ° C. at a rate and held at 50 ° C. for 5 minutes. The temperature of the inflection point that appears when the temperature is raised to 200 ° C. again at a rate of 20 ° C./min was defined as the glass transition temperature (° C.).
The Tg of the (meth) acrylic resin composition used in the comparative example was measured by the same procedure.

-Recrystallization temperature of the raw film The recrystallization temperature of the raw film was measured using a differential scanning calorimetry device "DSC7020" manufactured by Hitachi High-Tech Science Co., Ltd. Specifically, the peak temperature of the exothermic peak that appears when the sample is heated from 30 ° C. to 340 ° C. at a rate of 10 ° C./min in a nitrogen atmosphere was defined as the recrystallization temperature (° C.) of the raw film.

Linear expansion coefficient of stretched film and non-stretched film The stretched film obtained in Examples and Comparative Examples and the non-stretched film obtained in Comparative Example were cut into a width of 4 mm and a length of 20 mm to obtain a test piece, and thermomechanical analysis TMA ( Using "Q400EM" manufactured by TA Instruments), the temperature was raised from 25 ° C to 180 ° C at a heating rate of 10 ° C / min under the conditions of a chuck distance of 8 mm and a load of 0.01 N, and the dimensional change of the test piece was performed. The amount was measured. The coefficient of linear thermal expansion of each film was calculated from the slope of the amount of dimensional change in the temperature range of 50 to 150 ° C.

Shrinkage start temperature of stretched film and non-stretched film The stretched film obtained in Examples and Comparative Examples and the non-stretched film obtained in Comparative Example were cut into a width of 4 mm and a length of 20 mm to obtain a test piece, which was used as a thermomechanical analysis TMA (thermomechanical analysis TMA). Using "Q400EM" manufactured by TA Instruments), the temperature was raised from 25 ° C to 180 ° C at a heating rate of 10 ° C / min under the conditions of a chuck distance of 8 mm and a load of 0.01 N, and the dimensional change of the test piece was performed. The amount was measured. The temperature at which the inclination of the amount of dimensional change changed to minus was defined as the shrinkage start temperature of the stretched film.

・ Haze of stretched film and non-stretched film The stretched film obtained in Examples and Comparative Examples and the non-stretched film obtained in Comparative Example were cut into 50 mm × 50 mm pieces and used as test pieces, and a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd. The haze was measured using SH7000) according to JIS K 7136 (2000).

-Changes in tensile elastic modulus and elastic modulus of stretched film and non-stretched film The stretched film obtained in Examples and Comparative Examples and the non-stretched film obtained in Comparative Example are punched into a dumbbell No. 3 type (JIS K 6251 (2010)). , Tensile elastic modulus E (23) at 23 ° C. and Tensile elastic modulus E (85) at 85 ° C. using Autograph (manufactured by Shimadzu Corporation) under the conditions of chuck distance of 30 mm and tensile speed of 100 mm / min. (GPa) was measured. Then, the change in elastic modulus between 23 ° C. and 85 ° C. was calculated by the following formula (1).
Modulus change (%) = (E (85) -E (23)) / E (23) x 100 ... Equation (1)

Warpage and fine cracks in stretched film and non-stretched film UV curable hard coating agent 850-3L (manufactured by Aica Kogyo Co., Ltd.) was applied to the stretched film obtained in Examples and Comparative Examples and the non-stretched film obtained in Comparative Examples. The film was applied and heated in a dryer at 80 ° C. for 1 minute for drying. The film is installed on a conveyor type UV irradiation device (Eigrandage ECS-4011GX / N manufactured by Eye Graphics Co., Ltd.), and UV is emitted using a mercury lamp at a lamp output of 3 kW, a distance between lamps of 150 mm, and a conveyor speed of 4 m / min. Irradiation was performed to prepare a hard coat layer having a thickness of 20 μm. The treated film was taken out, and the presence or absence of warpage and the presence or absence of fine cracks in the film were visually observed. When fine cracks are generated, the film is whitened due to light scattering, so that it can be visually determined.

Flexibility of stretched film and non-stretched film The stretched film obtained in Examples and Comparative Examples and the non-stretched film obtained in Comparative Example were cut into 15 mm × 122 mm pieces and used as test pieces, and used as a test piece by a MIT bending tester (Toyo Seiki Co., Ltd. Flexibility was measured using a folding fatigue tester D-2) manufactured by Mfg. Co., Ltd. at a load of 250 g, a bending radius of 0.38 mm, a bending angle of 135 °, and a bending speed of 175 rpm according to JIS P 8115 (2001). If the number of bendings was 1000 or more, it was evaluated as acceptable (◯), and if it was less than 1000, it was evaluated as rejected (x).

"Composition"
(1) Preparation of Composition 1 2,6-naphthalenedicarboxylic acid 9203.2 g (42.6 mol), a mixture of 1,9-nonandiamine and 2-methyl-1,8-octanediamine [former / latter = 50 / 50 (molar ratio)] 6840.1 g (43.2 mol), 105.0 g (1.7 mol) of benzoic acid, 16.1 g of sodium hypophosphate monohydrate (0. 1% by mass) and 7.3 liters of distilled water were placed in an autoclave having an internal volume of 40 liters and replaced with nitrogen. The mixture was stirred at 100 ° C. for 30 minutes, and the temperature inside the autoclave was raised to 220 ° C. over 2 hours. At this time, the pressure inside the autoclave was boosted to 2 MPa. Heating was continued for 5 hours while maintaining the pressure at 2 MPa, and water vapor was gradually removed to react. Next, the pressure was lowered to 1.3 MPa over 30 minutes, and the reaction was carried out for another 1 hour to obtain a prepolymer. The obtained prepolymer was dried at 100 ° C. under reduced pressure for 12 hours and pulverized to a particle size of 2 mm or less. This was solid-phase polymerized at 230 ° C. and 13 Pa (0.1 mmHg) for 10 hours to obtain a semi-aromatic polyamide.
Sumilyzer GA-80 (manufactured by Sumitomo Chemical Co., Ltd.), which is a phenolic heat stabilizer, is dry-blended at a ratio of 0.2 parts by mass with 100 parts by mass of the above semi-aromatic polyamide, and a twin-screw extruder (Toshiba Machine Co., Ltd.) It was put into the upstream supply port of the company's "TEM-26SS") all at once. A pellet-shaped composition 1 was produced by melting and kneading at a cylinder temperature 20 to 30 ° C. higher than the melting point of the semi-aromatic polyamide, extruding, cooling and cutting.

(2) Preparation of Composition 2 With composition 1 except that the mixing ratio of 1,9-nonanediamine and 2-methyl-1,8-octanediamine is [former / latter = 85/15 (molar ratio)]. Composition 2 was produced in the same manner.

(3) Production of Composition 3 The inside of the autoclave to which the stirrer and the sampling tube were attached was replaced with nitrogen. To this, 100 parts by mass of distilled and purified methyl methacrylate (MMA), 2,2'-azobis (2-methylpropionitrile) (hydrogen extraction capacity: 1%, 1 hour half-life temperature: 83 ° C.) 0.0052 0.225 parts by mass and 0.225 parts by mass of n-octyl mercaptan were added and stirred to obtain a raw material solution. Nitrogen was sent into this raw material liquid to remove dissolved oxygen in the raw material liquid.
The raw material solution was filled up to 2/3 of the capacity in a tank reactor connected to the autoclave via a pipe. While the temperature was maintained at 140 ° C., the polymerization reaction was first started by a batch method. When the polymerization conversion rate reached 55% by mass, the raw material liquid was supplied from the autoclave to the tank reactor at a flow rate with an average residence time of 150 minutes while maintaining the temperature at 140 ° C., and at the same time, the supply flow rate of the raw material liquid was increased. The reaction was switched to a continuous flow type polymerization reaction in which the reaction solution was extracted from the tank reactor at a corresponding flow rate. After switching to the continuous distribution method, the polymerization conversion rate in the steady state was 55% by mass.
The reaction solution extracted from the tank reactor in a steady state was supplied to a multi-tube heat exchanger having an internal temperature of 230 ° C. at a flow rate having an average residence time of 2 minutes for heating. Next, the heated reaction solution was introduced into a flash evaporator to remove volatile components containing unreacted monomers as a main component to obtain a molten resin. The molten resin from which the volatile matter had been removed was supplied to a twin-screw extruder having an internal temperature of 260 ° C., discharged in a strand shape, and cut with a pelletizer to obtain a pellet-shaped (meth) acrylic resin (A).

The inside of the autoclave equipped with the stirrer and the sampling tube was replaced with nitrogen. To this, at room temperature, 2.9 parts by mass of toluene, 0.0045 parts by mass of 1,1,4,7,10,10-hexamethyltriethylenetetramine, and 0.45 M concentration of isobutylbis (2,6-). Di-t-butyl-4-methylphenoxy) 0.097 parts by mass of a toluene solution of aluminum and a solution of sec-butyllithium at a concentration of 1.3 M (solvent: 95% by mass of cyclohexane, 5% by mass of n-hexane) 0. 011 parts by mass was charged. With stirring, 100 parts by mass of distilled and purified MMA was added dropwise to these raw materials at 20 ° C. over 30 minutes. After completion of the dropping, the mixture was stirred at 20 ° C. for 90 minutes, and the color of the solution changed from yellow to colorless. The polymerization conversion rate of MMA at this time was 100%. 2.7 parts by mass of toluene was added to the obtained solution for dilution. Then, the diluted solution was poured into 180 parts by mass of methanol to obtain a precipitate. The obtained precipitate was dried at 80 ° C. and 140 Pa for 24 hours to obtain a (meth) acrylic resin (B).

80 parts by mass of (meth) acrylic resin (A), 20 parts by mass of (meth) acrylic resin (B), 1 part by mass of ultraviolet absorber (ADEKA, LA-F70), and polymer processing aid (Mitsubishi) 2 parts by mass of Metabrene P550A manufactured by Chemical Co., Ltd.) is mixed with a Henshell mixer and kneaded and extruded using a twin-screw extruder with a vent (KZW15-45MG manufactured by Technobel Co., Ltd.) set at 260 ° C. with a screw diameter of 15 mm to transfer the glass. Pellets of composition 3 of a methacrylic resin having a temperature Tg of 122 ° C. were obtained.

<< Production of original film >>
Using a small twin-screw extruder (φ15 mm, L / D = 45) and a T-die (width 150 mm, lip width 0.4 mm) manufactured by Technobel Co., Ltd., using the above composition 1 from the melting point of the composition 1. The raw film 1 having a thickness of 160 μm ± 20 μm was produced by melt extrusion at a cylinder temperature and a die temperature higher than 20 to 30 ° C. Further, the raw film 2 having a thickness of 40 μm ± 10 μm was prepared using the composition 1. Further, using the composition 2, a raw film 3 having a size of 200 μm ± 20 μm was prepared in the same procedure. Further, using the composition 3, a raw film 4 having a thickness of 225 μm ± 20 μm was prepared by the same procedure. Table 1 shows the material and thickness of each raw film.

[Example 1]
The raw film 1 was cut into a size of 100 mm × 100 mm, introduced into a biaxially stretched birefringence measuring device (SDR-563K manufactured by Eto Co., Ltd.), and preheated at 140 ° C. Next, the preheated raw film 1 was simultaneously biaxially stretched 4.0 times (2.0 times in the longitudinal direction and 2.0 times in the width direction) at 140 ° C. At this time, the stretching speed was 400% / min in both the longitudinal direction and the width direction. Then, the temperature was raised to 250 ° C., and the stretched film was heat-fixed for 3 minutes to obtain a stretched film having a thickness of 40 μm.

[Example 2]
A stretched film having a thickness of 70 μm was obtained by the same method as in Example 1 except that the stretching ratio was 2.3 times (1.5 times in the longitudinal direction and 1.5 times in the width direction).

[Example 3]
A stretched film having a thickness of 40 μm was obtained by the same method as in Example 1 except that the heat was fixed at 210 ° C.

[Example 4]
The raw film 3 was cut into 100 mm × 100 mm, introduced into a biaxially stretched birefringence measuring device (SDR-563K manufactured by Eto Co., Ltd.), and preheated at 130 ° C. Next, the preheated raw film 3 was simultaneously biaxially stretched 4.0 times (2.0 times in the longitudinal direction and 2.0 times in the width direction) at 130 ° C. At this time, the stretching speed was 400% / min in both the longitudinal direction and the width direction. Then, the temperature was raised to 230 ° C., and the stretched film was heat-fixed for 2 minutes to obtain a stretched film having a thickness of 50 μm.

[Comparative Example 1]
A stretched film having a thickness of 40 μm was obtained by the same method as in Example 1 except that heat fixing was not performed.

[Comparative Example 2]
After cutting the raw film 2 into 100 mm × 100 mm, it was introduced into a biaxially stretched birefringence measuring device (SDR-563K manufactured by Eto Co., Ltd.), and the raw film was heated at 250 ° C. for 3 minutes without stretching. The film was fixed to obtain a non-stretched film having a thickness of 40 μm. No shrinkage start temperature was observed because it was not stretched.

[Comparative Example 3]
The raw film 2 was used as it was for the measurement and evaluation of physical properties. No shrinkage start temperature was observed because it was not stretched.

[Comparative Example 4]
The raw film 4 was cut into 100 mm × 100 mm, introduced into a biaxially stretched birefringence measuring device (SDR-563K manufactured by Eto Co., Ltd.), and preheated at 145 ° C. Next, the preheated raw film was simultaneously biaxially stretched at 145 ° C. by 5.6 times (2.37 times in the longitudinal direction and 2.37 times in the width direction). At this time, the stretching speed was 400% / min in both the longitudinal direction and the width direction. Then, the temperature was lowered to 110 ° C., and the stretched film was heat-fixed for 1 minute to obtain a stretched film having a thickness of 40 μm.

Using the stretched films obtained in the above Examples and Comparative Examples, the above-mentioned various physical properties were measured and each evaluation was performed. The results are shown in Table 2. Table 2 also shows the physical property values of the compositions and raw film used in each of the examples and comparative examples.
Since the composition 3 used in Comparative Example 4 was an amorphous resin, the melting point and the crystallization temperature derived from the disappearance and formation of crystals were not observed.

The stretched films of Examples 1 to 4 have a smaller absolute value of the coefficient of linear expansion than Comparative Example 1 which is not heat-fixed, have excellent rigidity at high temperatures, and are compared to Comparative Example 2 which is not stretched. , The absolute value of the linear expansion coefficient and the haze are small, and the absolute value of the linear expansion coefficient and the change in elastic modulus are small as compared with Comparative Example 3 in which stretching and heat fixing are not performed. That is, it can be seen that when only stretching is performed without heat fixing, the transparency is excellent, but the heat resistance is insufficient. Further, it can be seen that the heat resistance is improved but the transparency is lowered when only heat fixing is performed without stretching. Further, it can be seen that the transparency is excellent without stretching and heat fixing, but the heat resistance is insufficient. Therefore, it can be understood that both the stretching step and the heat fixing step are required in order to achieve both heat resistance and transparency.
Further, the stretched films of Examples 1 to 4 have a lower stretch ratio than Comparative Example 4, but have a small change in linear expansion coefficient and elastic modulus, and are excellent in rigidity and flexibility at high temperatures. That is, it can be understood that by stretching an unstretched film containing a specific polyamide composition under specific conditions, it is possible to achieve both heat resistance, transparency, and flexibility.

Since the stretched film of the present invention is excellent in transparency, heat resistance, and flexibility, it can be suitably used as a protective material for a cover window or the like, particularly as a substrate material for a laminate such as a cover window. It is possible to provide a laminated body such as a cover window without warpage or fine cracks. Furthermore, it is possible to apply various types of hard coat layers such as a hard coat layer having higher hardness to the stretched film, and the stretch that can greatly improve the performance as a cover window or a laminate such as surface hardness. It is possible to provide a film.

1: Film 2: Hard coat layer 3: Cover window (laminated body)

Claims

A stretched film containing a semi-aromatic polyamide.
The semi-aromatic polyamide contains a dicarboxylic acid unit and a diamine unit, the dicarboxylic acid unit contains a naphthalenedicarboxylic acid unit, and the diamine unit contains an aliphatic diamine unit having 4 to 12 carbon atoms.
A stretched film having a coefficient of linear expansion from 50 ° C. to 150 ° C. of -50 × 10 -6 / ° C. or higher and 50 × 10 -6 / ° C. or lower.
When the tensile elastic modulus at 23 ° C. is E (23) and the tensile elastic modulus at 85 ° C. is E (85), it is represented by (E (85) -E (23)) / E (23) × 100. The stretched film according to claim 1, wherein the absolute value of the change in elastic modulus is 25% or less.
The stretched film according to claim 1 or 2, wherein 60 mol% or more and 100 mol% or less of the naphthalene dicarboxylic acid unit is 2,6-naphthalene dicarboxylic acid.
The stretched film according to any one of claims 1 to 3, wherein the aliphatic diamine unit having 4 to 12 carbon atoms contains an aliphatic diamine having 6 to 10 carbon atoms.
The stretched film according to any one of claims 1 to 4, wherein the aliphatic diamine unit having 4 to 12 carbon atoms contains an aliphatic diamine having 8 to 10 carbon atoms.
The stretched film according to any one of claims 1 to 5, wherein the aliphatic diamine unit contains 1,9-nonanediamine and 2-methyl-1,8-octanediamine.
A laminate containing the stretched film according to any one of claims 1 to 6.
A cover window comprising the stretched film according to any one of claims 1 to 6 or the laminate according to claim 7.
The method for producing a stretched film according to any one of claims 1 to 6.
An unstretched film containing the semi-aromatic polyamide was prepared.
A method for producing a stretched film, wherein the unstretched film is subjected to a stretching treatment including at least a stretching step.
A method for producing a stretched film containing a semi-aromatic polyamide.
The semi-aromatic polyamide contains a dicarboxylic acid unit and a diamine unit, the dicarboxylic acid unit contains a naphthalene dicarboxylic acid unit, and the diamine unit contains a diamine having 4 to 12 carbon atoms.
The stretching temperature is equal to or higher than the glass transition temperature of the semi-aromatic polyamide of −10 ° C. and lower than the recrystallization temperature of the unstretched film, the stretching rate is 100 to 5,000% / min, and the stretching ratio is 2 to 16 times. A method for producing a stretched film, wherein the heat fixing temperature is equal to or higher than the recrystallization temperature of the unstretched film.
The method for producing a stretched film according to claim 9 or 10, wherein 60 mol% or more and 100 mol% or less of the naphthalene dicarboxylic acid unit is 2,6-naphthalene dicarboxylic acid.
The method for producing a stretched film according to any one of claims 9 to 11, wherein the aliphatic diamine unit having 4 to 12 carbon atoms contains an aliphatic diamine having 6 to 10 carbon atoms.
The method for producing a stretched film according to any one of claims 9 to 12, wherein the aliphatic diamine unit having 4 to 12 carbon atoms contains an aliphatic diamine having 8 to 10 carbon atoms.
The method for producing a stretched film according to any one of claims 9 to 13, wherein the aliphatic diamine unit contains 1,9-nonanediamine and 2-methyl-1,8-octanediamine.