WO2011065313A1

WO2011065313A1 - Polycarbonate film for laser processing

Info

Publication number: WO2011065313A1
Application number: PCT/JP2010/070756
Authority: WO
Inventors: 秀幸常守; 学松井
Original assignee: 帝人化成株式会社
Priority date: 2009-11-24
Filing date: 2010-11-16
Publication date: 2011-06-03
Also published as: TW201129607A; JPWO2011065313A1

Abstract

Provided is a polycarbonate film for laser processing which has excellent heat resistance, excellent absorption characteristics at visible-region wavelengths, and excellent processing accuracy. The film for laser processing is a film formed from a polycarbonate resin which mainly comprises specific units and has a glass transition temperature of 180ºC or higher, the film having a light transmittance at a wavelength of 0.4 µm of 5-95%.

Description

Polycarbonate film for laser processing

The present invention relates to a polycarbonate film that can be patterned by irradiating laser light having a wavelength in the visible range, and an optical member that uses the polycarbonate film on which a pattern is formed.

Laser ablation means that the solid surface of the processing material is irradiated with pulsed laser light whose pulse width is shorter than several tens of nanoseconds and whose light intensity per pulse is several mW / cm ² or more, and the processing material at the irradiated part is decomposed. A processing method for forming a specific pattern by scattering. Conventionally, this laser ablation processing is industrially effective because it can process nano-patterns finely because of its high laser beam condensing capability, and it is non-contact and has high safety and high-speed processing. It is used as a processing method.
For example, when a CO ₂ laser (9 to 11 μm in the near infrared region) or a YAG laser (1.064 μm in the near infrared region) is used as the laser light source, the solid material to be processed is heated and dissolved with laser light, and then cut or It is possible to perform welding or the like. Such processing with a relatively long wavelength laser beam is a thermal processing based on the thermal effect of the laser beam, and metals and ceramics have been used as processing materials. However, when applied to polymer materials such as plastics, it is pointed out that the processing accuracy is remarkably inferior due to welding traces and thermal decomposition products due to the heat diffusion effect around the irradiated part of the laser beam, etc. Has been.
Therefore, a method of using an excimer laser using a short wavelength light source (193, 248, 308, 351 nm) as a light source has been studied. When an excimer laser is used, since the energy per photon is large, an electronically excited state of a processed material molecule is generated by laser light, and non-thermal processing by a photochemical effect accompanied by a chemical reaction is possible. Non-thermal processing has been proposed as a processing method of a polymer material having excellent processing accuracy as compared with the thermal processing. However, in order to actually obtain a good processed surface in non-thermal processing using a polymer material, it is necessary to formulate various measures. For example,

Patent Documents

1 and 2 disclose a method of promoting the generation of ablation by mixing carbon powder or an ultraviolet absorber in a difficult-to-ablate material. In addition, the excimer laser is not necessarily non-thermal processing, and heat is instantaneously generated at the laser beam irradiation site, and the accuracy of the processed surface is reduced.
On the other hand, Patent Document 3 discloses a polymer material that can be non-thermally ablated by laser light having a wavelength in the visible range. In this invention, the processed material is composed of two types of polymers, and one component thereof has at least two types of chromophores that generate an excited state by absorbing the irradiated laser beam, and the intermolecular distance is resonant. It was necessary to satisfy the complicated condition of the working range.
Patent Document 4 describes a technique in which a laser ablation process is performed by adding a dye that absorbs a wavelength of 0.4 μm to 11 μm using polyimide as a heat resistant polymer. However, in the examples, a neodymium YAG laser (1.064 μm in the near infrared region) is used as the laser beam, and there is no description about ablation processing using a laser beam with a wavelength in the visible region.
As described above, there is still no sufficient polymer material for laser ablation processing that is excellent in processing accuracy with laser light having a wavelength in the visible range.
JP 7-16924 A Japanese Patent Laid-Open No. 10-6046 JP-A-5-112727 JP 2002-254184 A

An object of the present invention is to provide a film for laser ablation processing excellent in heat resistance, wavelength absorption characteristics in the visible region, and processing accuracy.
Conventionally, polycarbonate films have been considered unsuitable for laser ablation because they have low heat resistance and inferior wavelength absorption characteristics in the visible range, but the present inventors surprisingly use specific polycarbonate films. Thus, the present inventors have found that the above problems can be solved and are extremely suitable for laser ablation processing with laser light having a wavelength in the visible range. As a result of further investigation based on this finding, the present invention has been completed.
The present invention mainly comprises a unit represented by the following formula (α), is formed from a polycarbonate resin having a glass transition temperature of 180 ° C. or higher, and has a light transmittance of 5 to 95% at a wavelength of 0.4 μm. It is a film for laser processing.

(Wherein, -W- is at least one linking group selected from the group consisting of the following formulas (α-1), (α-2), (α-3) and a single bond. X and y are Each independently represents an integer of 0 to 4. R ¹ and R ² each independently represent a halogen atom or an alkyl group having 1 to 4 carbon atoms.)

(In the formula, v and w are each independently an integer of 0 to 2. R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

(Wherein R ⁶ and R ⁷ are each independently (i) when x and y are 0, they are aryl groups having 6 to 10 carbon atoms; and (ii) x or y is an integer of 1 to 4). In this case, it is an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 10 carbon atoms.)

FIG. 1 shows a schematic diagram of laser ablation processing on the surface of a polymer material having a low glass transition temperature.
FIG. 2 shows a schematic view of laser ablation processing on the polycarbonate film surface of the present invention.

DESCRIPTION OF SYMBOLS 1 Laser beam 2 Objective lens 3 Processing material 4 Laser beam irradiation site | part 5 Thermal expansion 6 Thermal decomposition material 7 Processed surface

(I) Polycarbonate resin The polycarbonate resin used in the present invention mainly contains units represented by the following formula (α). Here, "mainly" means 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and most preferably, in 100 mol% of all carbonate units excluding terminals. Indicates a proportion of 100 mol%.

In the formula, -W- is at least one linking group selected from the group consisting of the following formulas (α-1), (α-2), (α-3) and a single bond. x and y are each independently an integer of 0 to 4. R ¹ and R ² are each independently a halogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group.

In the formula (α-1), v and w are each independently an integer of 0 to 2. R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, and a propyl group.
As the compound for deriving the unit of the formula (α-1), 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) cyclohexane, 1,1 -Bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 1,1-bis (4-hydroxy-3-methylphenyl) -3,3,5-trimethylcyclohexane, 1,1-bis (3 , 5-dimethyl-4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 1,1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane and the like. Of these, 1,1-bis (4-hydroxyphenyl) cyclohexane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane are preferable.

In formula (α-2), R ⁶ and R ⁷ are each independently (i) when x and y are 0, an aryl group having 6 to 10 carbon atoms, and (ii) when x or y is 1 to In the case of an integer of 4, it is an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 10 carbon atoms.
Examples of the aryl group having 6 to 10 carbon atoms include phenyl group, tolyl group, dimethylphenyl group and naphthyl group. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, and a propyl group.
Compounds that derive the unit of formula (α-2) include 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) ) Propane, 1-phenyl-1,1-bis (4-hydroxyphenyl) ethane, 4,4′-dihydroxytetraphenylmethane and the like. Of these, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane and 4,4′-dihydroxytetraphenylmethane are preferable.

As the compound for deriving the unit of the formula (α-3), 9,9-bis (4-hydroxy-3-methylphenyl) fluorene is preferable.
Examples of the compound that induces a structural unit in which W is a single bond include 4,4′-biphenol and 4,4′-bis (2,6-dimethyl) diphenol.
In addition, aromatic dihydroxy components derived from other dihydric phenols may be copolymerized at a ratio of 30 mol% or less, preferably 20 mol% or less, as long as the object and characteristics of the present invention are not impaired. Representative examples of such other aromatic dihydroxy components include bis (2-hydroxyphenyl) methane, bis (4-hydroxyphenyl) methane, and bis (4-hydroxy-2,6-dimethyl-3-methoxyphenyl). Methane, bis (4-hydroxyphenyl) cyclohexylmethane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane (usually referred to as “bisphenol A”), 2 , 2-bis (3-phenyl-4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis ( 4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) pentane, 4,4-bis (4-hydroxyphenyl) Butane, 2,2-bis (4-hydroxyphenyl) octane, 1,1-bis (4-hydroxyphenyl) decane, 1,1-bis (3-methyl-4-hydroxyphenyl) decane, and 1,1- Examples thereof include bis (2,3-dimethyl-4-hydroxyphenyl) decane, α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene (usually referred to as “bisphenol M”), and the like.
The polycarbonate resin is 40 to 95 mol%, preferably 45 to 90 mol%, more preferably 50 to 85 mol% of the unit represented by the following formula (I) and 60 to 5 mol%, preferably 55 to 10 mol%. %, More preferably 50 to 15 mol% of units represented by the following formula (II). When the unit represented by the formula (I) is less than 40 mol%, the heat resistance is insufficient. On the other hand, if it exceeds 95 mol%, the transparency of the molded product is lowered.

Examples of the method for producing the polycarbonate resin of the present invention include an interfacial polycondensation method, a melt transesterification method, a solid phase transesterification method of a carbonate prepolymer, and a ring-opening polymerization method of a cyclic carbonate compound.
The reaction by the interfacial polycondensation method is usually a reaction between a dihydric phenol and phosgene, and is reacted in the presence of an acid binder and an organic solvent. As the acid binder, for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or an amine compound such as pyridine is used. As the organic solvent, for example, halogenated hydrocarbons such as methylene chloride and chlorobenzene are used. In order to accelerate the reaction, a catalyst such as a tertiary amine such as triethylamine, tetra-n-butylammonium bromide or tetra-n-butylphosphonium bromide, a quaternary ammonium compound or a quaternary phosphonium compound may be used. it can. At that time, the reaction temperature is usually 0 to 40 ° C., the reaction time is preferably about 10 minutes to 5 hours, and the pH during the reaction is preferably maintained at 9 or more.
In this polymerization reaction, a terminal terminator is usually used. Monofunctional phenols can be used as such end terminators. Monofunctional phenols are commonly used as end terminators for molecular weight control, and the resulting polycarbonate resins are compared to those that do not because the ends are blocked by groups based on monofunctional phenols. Excellent thermal stability. Such monofunctional phenols are generally phenols or lower alkyl-substituted phenols, and monofunctional phenols represented by the following formula (β) can be shown.

In the formula, A is a hydrogen atom, a linear or branched alkyl group having 1 to 9 carbon atoms, or a phenyl-substituted alkyl group, and r is an integer of 1 to 5, preferably 1 to 3.
Specific examples of the monofunctional phenols include phenol, phenylphenol, p-tert-butylphenol, p-cumylphenol, tert-octylphenol and isooctylphenol.
Further, as other monofunctional phenols, phenols or benzoic acid chlorides having a long chain alkyl group or an aliphatic ester group as a substituent, or long chain alkyl carboxylic acid chlorides can be used.
These end terminators are desirably introduced at at least 5 mol%, preferably at least 10 mol%, and more preferably introduced at 80 mol% or more of the ends of the obtained polycarbonate resin. Is done. Moreover, you may use a terminal terminator individually or in mixture of 2 or more types.
The reaction by the melt polymerization method is typically a transesterification reaction between a dihydric phenol and a carbonate ester, and is produced by mixing the dihydric phenol and the carbonate ester with heating in the presence of an inert gas. It is carried out by a method of distilling alcohol or phenol. The reaction temperature varies depending on the boiling point of the alcohol or phenol produced, but is usually in the range of 120 to 350 ° C. In the latter stage of the reaction, the system is evacuated to about 1,300 Pa to 13 Pa (10 to 0.1 Torr) to facilitate the distillation of the alcohol or phenol produced. The reaction time is usually about 1 to 4 hours.
Examples of the carbonate ester include esters such as an aryl group having 6 to 10 carbon atoms, an aralkyl group, or an alkyl group having 1 to 4 carbon atoms which may have a substituent. Specific examples include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, dimethyl carbonate, diethyl carbonate, and dibutyl carbonate. Of these, diphenyl carbonate is preferred.
A polymerization catalyst can be used to increase the polymerization rate. Examples of the polymerization catalyst include alkali metal and alkaline earth metal hydroxides such as sodium hydroxide and potassium hydroxide, boron and aluminum hydroxides, alkali metal salts, alkaline earth metal salts, and quaternary ammonium salts. Alkoxides of alkali metals and alkaline earth metals, organic acid salts of alkali metals and alkaline earth metals, zinc compounds, boron compounds, silicon compounds, germanium compounds, organic tin compounds, lead compounds, antimony compounds, manganese compounds, titanium compounds And catalysts usually used for esterification reactions and transesterification reactions of zirconium compounds and the like. A catalyst may be used independently and may be used in combination of 2 or more types. These polymerization catalysts are preferably used in an amount of 1 × 10 ⁻⁹ to 1 × 10 ⁻⁵ equivalents, more preferably 1 × 10 ⁻⁸ to 5 × 10 ⁻⁶ equivalents, relative to 1 mol of dihydric phenol as a raw material. Selected by range.
Further, in the polymerization reaction, for example, 2-chlorophenylphenyl carbonate, 2-methoxycarbonylphenylphenyl carbonate and 2-ethoxycarbonylphenylphenyl carbonate are added at the later stage or after completion of the polymerization reaction in order to reduce the phenolic end groups. In particular, 2-methoxycarbonylphenyl phenyl carbonate is preferably used.
Further, in the melt transesterification method, it is preferable to use a deactivator that neutralizes the activity of the catalyst. The amount of the deactivator is preferably 0.5 to 50 moles per mole of the remaining catalyst. Further, it is used in a proportion of 0.01 to 500 ppm, more preferably 0.01 to 300 ppm, and particularly preferably 0.01 to 100 ppm with respect to the polycarbonate copolymer after polymerization. Preferred examples of the deactivator include phosphonium salts such as tetrabutylphosphonium dodecylbenzenesulfonate and ammonium salts such as tetraethylammonium dodecylbenzyl sulfate.
The viscosity average molecular weight (Mv) of the polycarbonate resin is preferably 2.0 × 10 ⁴ to 8.0 × 10 ⁴ , more preferably 2.5 × 10 ⁴ to 7.0 × 10 ⁴ , and still more preferably Is 3.0 × 10 ⁴ to 6.0 × 10 ⁴ . A polycarbonate resin having a viscosity average molecular weight of less than 2.0 × 10 ⁴ may not provide a practically sufficient strength. On the other hand, a polycarbonate resin having a viscosity average molecular weight of more than 8.0 × 10 ⁴ is not preferable because the melt viscosity and the solution viscosity become high and handling becomes difficult.
First, the viscosity average molecular weight of the polycarbonate resin is determined using an Ostwald viscometer from a solution in which 0.7 g of the polycarbonate resin is dissolved in 100 ml of methylene chloride at 20 ° C., with a specific viscosity (η _SP ) calculated by the following formula:
Specific viscosity (η _SP ) = (t−t ₀ ) / t ₀
[T ₀ is methylene chloride falling seconds, t is sample solution falling seconds]
From the obtained specific viscosity (η _SP ), the viscosity average molecular weight (Mv) is calculated by the following formula.
η _SP /c=[η]+0.45×[η] ² c (where [η] is the intrinsic viscosity)
[Η] = 1.23 × 10 ⁻⁴ Mv ^0.83
c = 0.7
The polycarbonate resin has a glass transition temperature (Tg) of 180 ° C. or higher, preferably 180 ° C. to 260 ° C., more preferably 200 to 250 ° C. If Tg is less than 180 ° C., welding marks and the like due to the heat of the laser beam remain around the irradiation position, and the processing accuracy is lowered. On the other hand, when Tg exceeds 260 ° C., the melt viscosity and the solution viscosity become high, and handling at the time of film production becomes difficult. The glass transition temperature in the present invention can be measured by using a differential scanning calorimeter (DSC) at a heating rate of 20 ° C./min in accordance with JIS K7121.
The polycarbonate resin has a light transmittance at a wavelength of 0.4 μm of 5 to 95%, preferably 5 to 90%, more preferably 5 to 85%, and further preferably 10 to 85%. If the light transmittance exceeds 95%, the absorption characteristics of the irradiated laser beam are inferior, which is not preferable. When the light transmittance is less than 5%, the laser beam is not transmitted, so that it cannot be used for an optical member or an optical element that transmits the laser beam.
The light transmittance of the polycarbonate resin is measured as follows. That is, the light transmittance in the visible region with a wavelength of 0.4 μm can be measured with a UV-visible spectrophotometer using a polycarbonate film having a thickness of 200 μm.
(II) Ultraviolet Absorber Examples of the ultraviolet absorber used in the present invention include benzotriazole-based and / or benzophenone-based and / or triazine-based and / or benzoxazine-based ultraviolet absorbers.
Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole and 2- (2′-hydroxy-3 ′-(3,4,5,6-tetrahydrophthalimidomethyl). ) -5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert-octylphenyl) ) Benzotriazole, 2- (3'-tert-butyl-5'-methyl-2'-hydroxyphenyl) -5-chlorobenzotriazole, 2,2'-methylenebis (4- (1,1,3,3- Tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2′-hydroxy-3 ′, 5′-bis (α, α-dimethylben) L) phenyl) -2H-benzotriazole, 2- (3 ′, 5′-di-tert-amyl-2′-hydroxyphenyl) benzotriazole, 5-trifluoromethyl-2- (2-hydroxy-3- ( 4-methoxy-α-cumyl) -5-tert-butylphenyl) -2H-benzotriazole and the like. Among them, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′-(3,4,5,6-tetrahydrophthalimidomethyl) -5′-methylphenyl) Benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2- (3 '-Tert-butyl-5'-methyl-2'-hydroxyphenyl) -5-chlorobenzotriazole is preferred, and 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole is more preferred.
As the triazine-based ultraviolet absorber, hydroxyphenyltriazine-based, for example, trade name Tinuvin 400 (manufactured by Ciba Specialty Chemicals) is preferable.
Examples of the benzoxazine-based ultraviolet absorber include 2,2′-bis (3,1-benzoxazin-4-one), 2,2′-p-phenylenebis (3,1-benzoxazin-4-one) 2,2′-m-phenylenebis (3,1-benzoxazin-4-one), 2,2 ′-(4,4′-diphenylene) bis (3,1-benzoxazin-4-one), 2,2 ′-(2,6-naphthalene) bis (3,1-benzoxazin-4-one), 2,2 ′-(1,5-naphthalene) bis (3,1-benzoxazin-4-one) ), 2,2 ′-(2-methyl-p-phenylene) bis (3,1-benzoxazin-4-one), 2,2 ′-(2-nitro-p-phenylene) bis (3,1- Benzoxazin-4-one), and 2,2 ′-(2-chloro-p-phenylene) bi (3,1-benzoxazin-4-one) and the like. Among them, 2,2′-p-phenylenebis (3,1-benzoxazin-4-one), 2,2 ′-(4,4′-diphenylene) bis (3,1-benzoxazin-4-one), And 2,2 ′-(2,6-naphthalene) bis (3,1-benzoxazin-4-one) are preferred. In particular, 2,2′-p-phenylenebis (3,1-benzoxazin-4-one) is preferable.
Moreover, as an ultraviolet absorber other than the above, a compound represented by the following formula (γ-1) is preferably used, and in particular, a compound represented by the following formula (γ-1) is represented by the following formula [γ-2]. It is preferable that it is a compound represented by these.

(Wherein R ⁸ and R ¹¹ represent a hydrogen atom, an alkyl group or an alkoxy group, R ⁹ and R ¹⁰ represent an alkyl group, and [B] represents a substituted aryl or ethenyl group.)

(Wherein R ¹² and R ¹⁴ are groups having the same meaning as R ⁹ , R ¹³ and R ¹⁵ are groups having the same meaning as R ^10, and n represents an integer of 1 or 2).
Furthermore, as an ultraviolet absorber other than the above, a compound represented by the following formula (γ-3) is preferably used, and among them, 2,2 ′-(thiophene-2) represented by the following formula (γ-4) , 5-diyl) bis (4H-benzo [d] [1,3-oxazin-4-one].

(R ^a , R ^b , R ^c , R ^d , R ^e , R ^f , R ^g , R ^h , R ⁱ and R ^j each independently represent a hydrogen atom or a monovalent substituent.)

The said ultraviolet absorber can be used individually or in combination of 2 or more types. The blending amount of the ultraviolet absorber is preferably 0.001 to 3.0 parts by weight, more preferably 0.005 to 1.5 parts by weight, and still more preferably 0.001 to 3.0 parts by weight with respect to 100 parts by weight of the polycarbonate resin. 01 to 1.0 part by weight. If the blending amount of the UV absorber is less than 0.001 part by weight, the wavelength absorption characteristics will deteriorate, so it will be necessary to increase the irradiation intensity and irradiation time of the laser beam, and it will melt on the processed surface due to the heat of the laser beam Scratches or the like may occur, and the processing accuracy may decrease. Moreover, when the compounding quantity of a ultraviolet absorber exceeds 3.0 weight part, since heat resistance falls, it is unpreferable.
A fluorescent dye may be used in combination with the ultraviolet absorber. Examples of the fluorescent dye include a coumarin fluorescent dye, a benzopyran fluorescent dye, a perylene fluorescent dye, an anthraquinone fluorescent dye, a thioindigo fluorescent dye, a xanthene fluorescent dye, a xanthone fluorescent dye, a thioxanthene fluorescent dye, and a thioxanthone. Fluorescent dyes, thiazine fluorescent dyes, and diaminostilbene fluorescent dyes. Among these, coumarin fluorescent dyes, benzopyran fluorescent dyes, and perylene fluorescent dyes are preferable. Of these, coumarin-based fluorescent dyes, that is, fluorescent dyes composed of coumarin derivatives exhibit preferable characteristics. When the fluorescent dye is used, the range of 0.001 to 1 part by weight is preferable with respect to 100 parts by weight of the polycarbonate resin.
(III) Polycarbonate Film Next, a method for producing the film for laser processing of the present invention will be described. Examples of the method for producing the film of the present invention include a solution casting method and a melt extrusion method. In the present invention, since the polycarbonate resin has a high glass transition temperature, the solution casting method is suitable from the viewpoint of workability. In addition to the fact that there are few foreign substances in the film and that it is easy to obtain a film with a low phase difference, the solution casting method obtains a film that has a good surface property, little variation in thickness, and is extremely flat. It is also excellent in that it can. Hereinafter, this solution casting method will be described in detail.
Solvents that can be used in the solution casting method can be selected from known dissolving solvents, among which methylene chloride, 1,3-dioxolane, and mixtures thereof are suitable solvents. Further, a small amount of a non-solvent of polycarbonate such as alcohol or xylene may be mixed and used as a secondary solvent.
The polymer concentration of the solution used for the solution casting method is preferably in the range of 10 to 40% (% by weight, the same applies hereinafter). When the concentration of the polycarbonate in the solution is too low, the amount of the solvent to be volatilized increases, which is not efficient. In addition, the solution viscosity becomes too small to obtain a uniform film. On the other hand, when the polycarbonate concentration in the solution is too high, the solution viscosity becomes high, and it becomes difficult to perform uniform casting. Absent. It is preferable to pass a filter having an average opening of about 1 to 10 μm before casting the solution in order to prevent foreign matters or gels in the solution from entering the film.
As the support for casting the solution in the solution casting method, a conventionally known one can be applied. For example, a polyester film or a steel belt having a very highly polished surface can be used. In the optical film of the present invention, it is particularly preferable to use the latter in order to obtain the surface in an ultra flat state. The surface property expressed by Ra (centerline average surface roughness) of the support surface is preferably 5 nm or less, more preferably 3 nm or less.
The thickness of the film of the present invention is preferably in the range of 1 to 600 μm. If it is less than 1 μm, the strength is insufficient, such being undesirable. If it exceeds 600 μm, it is necessary to remarkably slow the film forming speed, which is not preferable because productivity is lowered. The preferred thickness is 10 to 450 μm, more preferably 50 to 300 μm.
The thickness unevenness of the film of the present invention should be small. Although the thickness unevenness varies depending on the thickness of the film, the range of the thickness unevenness is preferably 5% or less, more preferably 3% or less, and further preferably 1% or less with respect to the thickness. Here, 5% of thickness unevenness means, for example, that the difference between the maximum value and the minimum value of the thickness is 10 μm in a film having a thickness of 200 μm. If the thickness unevenness is larger than 5%, the surface smoothness is impaired. The method for measuring the thickness unevenness of the film can be performed, for example, using a continuous thickness meter (Film Thickness Tester Model KG601A manufactured by Anritsu Co., Ltd.).
The higher the total light transmittance of the film of the present invention is desirable, preferably 80% or more, more preferably 85% or more, and further preferably 89% or more. If the total light transmittance of the film is too low, it will be difficult to use as an optical member.
The in-plane retardation of the film of the present invention is preferably low. The phase difference (Re) is preferably 20 nm or less, more preferably 10 nm or less, still more preferably 8 nm or less, and particularly preferably 5 nm or less at the wavelength of the laser beam to be used. Ideally, this value is as close to zero as possible. If the in-plane retardation exceeds 20 nm, the processing accuracy deteriorates when the film is irradiated with laser light. The in-plane retardation value (Re) can be measured using an ellipsometer (JASCO Ellipsometer Model M-220).
(IV) Laser Ablation Processing Hereinafter, the laser ablation processing method for the film of the present invention will be described with reference to the drawings. FIG. 1 schematically shows the steps of a laser ablation method when a polymer material having a low glass transition temperature is used as a processing material. When the laser beam 1 is condensed by the objective lens 2 and irradiated onto the solid surface of the processing material 3, the processing material 3 at the laser beam irradiation site 4 easily generates thermal expansion 5, and the thermal decomposition product 6 is scattered. At that time, since the melting / decomposition occurs in a state in which the processed material 3 is deformed, the accuracy of the processed surface 7 is lowered.
On the other hand, the case where the film of the present invention having a high glass transition temperature is used as the processing material 3 is shown in FIG. When the laser light 1 collected by the objective lens 2 is irradiated, the laser light irradiation portion 4 undergoes a melting / decomposition reaction while being hardly deformed to form a pattern. As a result, a good processed surface 7 is obtained. However, if a processing material with a high glass transition temperature but low wavelength absorption characteristics of the laser beam used is used, it is necessary to increase the irradiation intensity and irradiation time of the laser beam to form a pattern. As in FIG. 1, thermal expansion and thermal decomposition occur due to excessive laser light irradiation, and the processed surface 7 is greatly disturbed.
As the laser light, various lasers having a wavelength in the visible range of 0.4 to 0.6 μm can be used. For example, the second harmonic of Nd: YAG laser (wavelength 533 nm), argon laser, krypton laser, dye laser Examples thereof include a titanium sapphire laser, an InGaN / GaN blue semiconductor laser, and a GaN green semiconductor laser. As the laser light, a pulse laser is usually used.
The power (intensity) of the laser light is usually preferably 10 ⁴ W / cm ² or more (for example, 5 × 10 ⁵ to 100 × 10 ⁵ W / cm ² , more preferably 10 × at the focal point (focal point). 10 ⁵ to 100 × 10 ⁵ W / cm ² , more preferably about 25 × 10 ⁵ to 100 × 10 ⁵ W / cm ² ). The average output of the laser beam is preferably 10 to 1,000 mW, more preferably 20 to 800 mW.
The pulse width of the laser beam (pulse laser beam) is preferably 1 picosecond or less (for example, about 10 to 500 femtoseconds, more preferably about 30 to 300 femtoseconds, and further preferably about 50 to 200 femtoseconds). The frequency of the laser beam (pulse laser beam) is preferably 0.1 kHz or more (for example, about 0.5 to 1,000 kHz, more preferably 0.5 to 800 kHz, and further preferably about 0.5 to 500 kHz). is there.
The irradiation time of the laser beam is preferably 1 microsecond (10 ⁻⁶ seconds) or less, particularly 100 femtoseconds (10 ⁻¹³ ), in order to prevent the heat generated at the irradiation site from being diffused excessively. Seconds) to 500 nanoseconds (5 × 10 ⁻⁷ seconds). As for the irradiation time, a mechanical, electrical, or optical shutter may be used individually or in combination with the continuous wave laser, and a pulsed laser is more preferably used.
The present invention includes a decorative film obtained by laser processing the film of the present invention and having a pattern formed on the film surface. Moreover, the optical member or optical element using a decorating film is included.

Examples of the polycarbonate film of the present invention will be described below, but the present invention is not limited to these examples. In the following examples and comparative examples, the measurement methods of the respective characteristics are as follows.
(1) Viscosity average molecular weight The viscosity average molecular weight of the resin composition in the present invention is measured and calculated by the following method.
First, the polycarbonate resin powder was mixed with 30 times weight of methylene chloride and dissolved, and the soluble component was collected by Celite filtration. Thereafter, the solid obtained after removing the solvent from the obtained solution was sufficiently dried, and the specific viscosity (η _sp ) of the solution at 20 ° C. was obtained from a solution obtained by dissolving 0.7 g of the solid in 100 ml of methylene chloride. Was measured. And Mv computed by the following formula was made into the viscosity average molecular weight.
η _sp /c=[η]+0.45×[η] ² c
[Η] = 1.23 × 10 ⁻⁴ Mv ^0.83
η _sp : specific viscosity η: intrinsic viscosity c: constant (= 0.7)
Mv: Viscosity average molecular weight (2) Glass transition temperature Using polycarbonate resin powder as a measurement sample and using a thermal analysis system DSC-2910 manufactured by TA Instruments, in accordance with JIS K7121, under a nitrogen atmosphere (nitrogen flow rate: 40 ml / min), temperature increase rate: measured at 20 ° C./min.
(3) Light transmittance The light transmittance of the film was measured with a spectrophotometer manufactured by Hitachi High-Technologies, model U-4100, with a wavelength of 0.4 μm.
(4) Thickness of film, thickness variation The thickness of the entire film thickness was measured using a continuous thickness meter (Film Thickness Tester, model KG601A manufactured by Anritsu Co., Ltd.). Measurement was performed at 10 mm width intervals, the average value was the film thickness, and the difference between the maximum value and the minimum value was the thickness unevenness.
(5) Total light transmittance of film Samples (length: 50 mm, width: 50 mm) were collected from three places in the width direction of the film (two places of 500 mm from the central portion and both end faces). The total light transmittance of the sample was measured using a color difference / turbidity measuring machine COH-300A manufactured by Nippon Denshoku Industries Co., Ltd. Five points were measured for each sample, and the average value was taken as the total light transmittance. This measurement was performed according to JIS K7105.
(6) Measurement of in-plane retardation value (Re) Retardation values were measured at intervals of 10 mm using a continuous retardation measuring instrument (trade name KOBRA-WFD manufactured by Oji Scientific Instruments Co., Ltd.) with respect to the full width of the sample in the width direction. The wavelength was measured at 0.4 μm.
(7) Laser ablation processing of film surface Pulse laser light was condensed and irradiated on the film surface with a lens. The laser beam used was a titanium sapphire laser. The wavelength was 0.4 μm, the pulse width was 150 femtoseconds, the repetition frequency was 200 kHz, and the pulsed laser beam was condensed with an objective lens with NA = 0.4. The irradiation time was 300 nanoseconds. The average output of the laser beam was changed, the processed surface was observed with an optical microscope, and the average output of the laser beam required for ablation was measured.
The following raw materials were used.
(Bisphenol monomer)
BIS-1: 9,9-bis (4-hydroxy-3-methylphenyl) fluorene BIS-2: 2,2-bis (4-hydroxyphenyl) propane BIS-A: 1,1-bis (4-hydroxyphenyl) ) Cyclohexane BIS-B: 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane BIS-C: 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane BIS-D: 4,4′-dihydroxytetraphenylmethane BIS-E: 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane (UV absorber)
UVA-1: 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole (Chemisorb 79 manufactured by Chemipro Kasei Co., Ltd.)
UVA-2: 2- (3′-tert-butyl-5′-methyl-2′-hydroxyphenyl) -5-chlorobenzotriazole (Tinubin 326 manufactured by Ciba Specialty Chemicals)
UVA-3: 2,2 ′-(thiophene-2,5-diyl) bis (4H-benzo [d] [1,3-oxazin-4-one]
Examples 1 to 13 and Comparative Examples 1 to 4
(1) Manufacture of polycarbonate resin The polycarbonate resin powder which consists of a mixture ratio of Table 1 and Table 2 was created in the following ways. A reactor equipped with a thermometer, a stirrer and a reflux condenser was charged with a 48% aqueous sodium hydroxide solution and ion-exchanged water, and bisphenol monomer and hydrosulfite were dissolved therein, and then methylene chloride was added thereto. Phosgene was blown in at about 15 to 25 ° C. over about 60 minutes. After completion of the phosgene blowing, the stirring was stopped, and a 48% aqueous sodium hydroxide solution and p-tert-butylphenol were added. Stirring was resumed, triethylamine was added after emulsification, and the mixture was further stirred at 28 to 33 ° C. for 1 hour to complete the reaction. After completion of the reaction, the product is diluted with methylene chloride, washed with water, acidified with hydrochloric acid, washed with water, and further washed with water until the conductivity of the aqueous phase becomes substantially the same as that of ion-exchanged water. Got. Next, this solution is passed through a filter having an aperture of 0.3 μm, and further dropped into warm water in a kneader with an isolation chamber having a foreign matter outlet at the bearing, and the polycarbonate resin is flaked while distilling off methylene chloride. The liquid-containing flakes were pulverized and dried to obtain a powder. Using this powder, the viscosity average molecular weight and glass transition temperature were measured, and the results are shown in Tables 1 and 2.
(2) Preparation of polycarbonate film The polycarbonate resin powder was dried with hot air at 120 ° C for 16 hours, and then cooled to 30 ° C with dehumidified air. This was dissolved in methylene chloride to prepare a 19% by weight solution. This solution was passed through a filter having an average pore diameter of 3 microns to remove foreign matters. Further, this solution was introduced into a coat hanger die having a width of 1,500 mm. Subsequently, after casting on a mirror-polished steel belt support, the solvent was blown off by heat drying, and the film was peeled off from the support. Further, the membrane was passed through a roll-suspended dryer. Then, it wound up with low conveyance tension. The thickness, thickness unevenness, light transmittance at a wavelength of 0.4 μm, total light transmittance, and in-plane retardation value of the obtained polycarbonate film were measured and listed in Tables 1 and 2. Moreover, when adding an ultraviolet absorber, the ultraviolet absorber was dissolved together when the polycarbonate resin powder was dissolved in methylene chloride.
(3) Laser ablation processing The obtained polycarbonate film was cut into a 100 mm square size, the film was placed on a sample stage, and the film surface was subjected to laser ablation processing according to the evaluation method (7) to obtain a decorative film. It was. The processed surface was observed with an optical microscope, and the average output of laser light necessary for ablation to occur was measured and listed in Tables 1 and 2.

As is apparent from the results of Tables 1 and 2, the polycarbonate film of the present invention can provide a good processed surface for laser ablation, while the useful polymer material having a low glass transition temperature has such useful properties. It can be seen that cannot be obtained. In addition, the light transmittance in the laser light of the wavelength used for laser processing can be improved by blending the ultraviolet absorber in a specific range, and the average output during laser ablation processing can be reduced. . That is, according to the polycarbonate film of this invention, it turns out that the favorable laser ablation process which cannot be obtained with the polymeric material with a low glass transition temperature used widely is possible.
Effects of the Invention The film of the present invention has high heat resistance, excellent wavelength absorption characteristics in the visible region, and excellent processing accuracy by laser ablation.

Since the film of the present invention can form a pattern by laser light irradiation, it is an optical member or optical element, such as various optical waveguides, nonlinear optical elements, optical switches, optical diffraction elements, light emission It can be used as an element, an amplifying element or the like.

Claims

A film for laser processing, which mainly contains a unit represented by the following formula (α), is formed from a polycarbonate resin having a glass transition temperature of 180 ° C. or higher, and has a light transmittance of 5 to 95% at a wavelength of 0.4 μm. .

(Wherein, -W- is at least one linking group selected from the group consisting of the following formulas (α-1), (α-2), (α-3) and a single bond. X and y are Each independently represents an integer of 0 to 4. R 1 and R 2 each independently represent a halogen atom or an alkyl group having 1 to 4 carbon atoms.)

(In the formula, v and w are each independently an integer of 0 to 2. R 3 , R 4 and R 5 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

(Wherein R 6 and R 7 are each independently (i) when x and y are 0, they are aryl groups having 6 to 10 carbon atoms; and (ii) x or y is an integer of 1 to 4). In this case, it is an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 10 carbon atoms.)
The film according to claim 1, wherein the polycarbonate resin contains 40 to 95 mol% of a unit represented by the following formula (I) and 60 to 5 mol% of a unit represented by the following formula (II).
The film according to claim 1, comprising 0.001 to 3 parts by weight of an ultraviolet absorber with respect to 100 parts by weight of the polycarbonate resin.
2. The film according to claim 1, wherein the polycarbonate resin has a viscosity average molecular weight in the range of 2.0 × 10 4 to 8.0 × 10 4 .
The film according to claim 1, which has a light transmittance of 5 to 85% at a wavelength of 0.4 µm.
A decorative film in which the film according to claim 1 is laser processed to form a pattern on the film surface.
An optical member or optical element using the decorative film according to claim 6.