JP2818828B2 - Film heat treatment equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a film heat treatment apparatus, and more particularly to a film heat treatment apparatus for producing an optically isotropic thermoplastic film.

[Conventional technology]

Conventionally, an optically isotropic film is used for the surface of a liquid crystal display, an electroluminescence display, and a polarizing plate widely used in watches, televisions, IC cards, word processors, personal computers, instrument panels, various display panels, and the like. In recent years, it has been particularly used as a protective film and a transparent conductive film, as well as a surface protective film for optical floppy disks and optical cards.

Various methods and apparatuses for producing such films having optical isotropy have been proposed, but none of them have extremely low productivity, and an apparatus for efficiently and easily producing films has not yet been developed.

As a conventionally proposed method and apparatus, for example, as shown in JP-A-62-87321, the temperature of the film end is lower than that of the film center, and the birefringence is controlled, and the film is stretched by increasing the thickness. And JP-A-62-222812.
In the heat treatment step, as shown in the item
A method of performing a heat treatment in a temperature range of ° C. for 1 minute or more is known.

However, in these methods and apparatuses, even in the film width direction, only a very small portion at the center shows optical isotropy, and the edges are inferior in isotropy. The absorption rate is extremely low, and the industry has demanded the development of a film heat treatment apparatus which is excellent in production efficiency and can be easily operated.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a completely novel film heat treatment apparatus which has not been known.

[Means for solving the problem]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In a film heat treatment apparatus for producing a thermoplastic film having optical isotropy, (a) preheating for heating a film to Tg or more. (B) Next, when cooling the film, the cooling rate is controlled at least within a temperature range of (Tg + 10) ° C to (Tg-15) ° C from 1 ° C / sec to 0.01 ° C / sec. And a cooling step equipped with an auxiliary heating device for heating at least one end of the film under the above-mentioned conditions.

If one example of the present film heat treatment apparatus is schematically shown,
And it becomes like FIG. FIG. 1 is a plan view of the present film heat treatment apparatus, and FIG. 2 is a side view.

1 and 2, reference numeral 1 denotes a film preheating step area, 2 denotes a cooling step area, 3 denotes a curing step area, 4 denotes an auxiliary heating device, 5 denotes a film gripper, and 6 denotes a film.

The phrase “having optical isotropy” in the present invention means that the polymer molecular chains are in an irregular structure (arrangement) state, and that the film has excellent birefringence in physical properties.

As a method for measuring the birefringence, for example, a polarizing microscope (OPTIPHOT-POL type) manufactured by Nippon Kogaku Kogyo Co., Ltd. can be used, and the birefringence can be measured by the Senarmont compensator method.

The film heat treatment apparatus according to the present invention mainly comprises a film preheating step, a cooling step and, if necessary, a curing step. In the cooling step, in particular, an auxiliary heating apparatus for heating at least one end of the film. It is characterized by being equipped with. Hereinafter, each step will be described in detail.

(A) Preheating step The aromatic polyester resin film is heated to a glass transition temperature (hereinafter referred to as “Tg”) or more, preferably (Tg + 10).
This is a step of preheating to 1 ° C., more preferably (Tg + 20) ° C., particularly preferably (Tg + 35) ° C., for 1 minute, preferably 2 minutes, more preferably 3 minutes or more.

The heating method used in the preheating step, the subsequent cooling step, and the curing step is not particularly limited, and a commonly used heating method is used. Generally, an electric heater, an infrared ray, a remote There are an infrared lamp, an oil or gas burner, etc., and there are a direct heating method or an indirect heating method using these heat sources, and an electromagnetic heating method. Among them, an indirect heating method using an electric heater and a burner is preferable.

(B) Cooling Step The cooling step in the present invention is a step of cooling the film heated in the above-mentioned preheating step. However, unlike the conventional apparatus, the film is not cooled uniformly over the entire film, but at least the film is cooled. This is a step of gradually cooling the film in the vicinity of the film holding portion at one end, preferably in the vicinity of the film holding portions at both ends of the film while supplementarily heating the film with the auxiliary heating device 4, and finally cooling the film to Tg or less.

 Hereinafter, the cooling step will be described in more detail.

(B-1) Slow cooling step The film preheated in the preheating step is
(Tg-1) at a cooling rate of (0,01) ° C / sec, preferably (0.8-0.05) ° C / sec, more preferably (0.5-0.1) ° C / sec.
5) This is a step of gradually cooling the mixture to ℃, preferably to (Tg-65) ℃, more preferably to (Tg-100) ℃. This step is particularly called a "gradual cooling step".

In the slow cooling step, it is also possible to partially shorten the cooling time if necessary.

That is, as described in detail below, in the above-described slow cooling step, the film is gradually cooled and then rapidly cooled.

(B-2) Gradual cooling / cooling step The film preheated in the preheating step is replaced with (Tg
+20) ° C, preferably up to (Tg + 10) ° C, more preferably up to (Tg ± 0) ° C, (1 to 0.01) ° C / sec, preferably (0.8 to 0.05) ° C / sec, more preferably (0.5 to 0.05) ° C.
0.1) Cool slowly at a cooling rate of 0.1 ° C / sec, then (Tg-15)
° C, preferably up to (Tg-65) ° C, more preferably up to (Tg-100) ° C, (50-1) ° C / sec, preferably (10-1) ° C / sec, more preferably (5-1) ° C / sec. 1) A step of rapidly cooling at a cooling rate of ° C./sec (hereinafter, this step is referred to as “gradual cooling / rapid cooling step”).

As described above, the feature of the present invention is that the whole film is not uniformly cooled in the cooling step, and at least one film near the film holding portion, preferably near the film holding portion at both ends of the film, is heated by the auxiliary heating device 4. It cools while performing auxiliary heating.

By this film auxiliary heating step, it has become possible to dramatically improve the yield of the optically isotropic film. The auxiliary heating temperature is higher than the film temperature (2-
It must be kept at a high temperature of 100) C, preferably (5 to 80) C, more preferably (10 to 50) C.

The film to be heated by the auxiliary heating device has a higher film yield as the film is closer to the film gripping portion. However, if the film is too close, the film may be cut from the film gripping portion and the operability is reduced. ~ 50) m / m, preferably around (5-30) m / m. The width of the film to be auxiliary-heated is not particularly limited, but is preferably narrower from the viewpoint of film yield, and is generally 50 m / m or less, preferably 30 m / m or less, and more preferably 10 m / m or less. . The heating method used for the auxiliary heating is not particularly limited, and a commonly used heating method is used. Generally, a direct or indirect method using a far-infrared lamp, an electric heater, an oil or gas burner, or the like is used. There are a heating method and an electromagnetic heating method, and among them, a far-infrared lamp heating method is preferable.

The film holding method used in the present film heat treatment apparatus is not particularly limited, and a generally used holding method is used, for example, a clip method, a pin method, a belt method, and the like, with the clip method being preferable.

(3) Curing step The curing step referred to in the present invention is a step following the above-mentioned cooling step, which is installed as necessary. Depending on the thermoplastic resin, it is gradually cooled until cooled to room temperature.・ This is the curing process.

As the thermoplastic film used in the film heat treatment apparatus obtained as described above, any one can be used. As the thermoplastic resin used as a material, for example, polycarbonate (PC), polyarylate (PAR ),
Olefin resins such as polyethylene (PE) and polypropylene (PP); vinyl resins such as polyvinyl chloride (PVC), polyvinyl acetate (PVAc), polyvinylidene chloride (PVDC), polyvinyl alcohol (PVA) and polystyrene (PS) Resins: Cellulose resins such as cellulose diacetate (CDA), cellulose triacetate (CTA), cellulose acetate butyrate (CAB) and cellulose propionate; Amide resins such as nylon 6, nylon 66 and nylon 11; polyacrylate ( Acrylic resins such as PA) and polymethacrylate; urethane resins; tetrafluoroethylene (PTFE), polyvinyl difluoride (PVDF), polyvinyl fluoride (PVF), ethylene-
Tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP),
Polymonochlorotrifluoroethylene (PCTFE), ethylene-monochlorotrifluoroethylene copolymer (ECTF
E), fluorine-based resins such as tetrafluoroethylene-polyfluorovinylether copolymer (PFA); various engineering plastics and aromatic polyester-based resins, among which fluorine-based resins, engineering plastics, and aromatic polyester-based resins Is preferable, and an aromatic polyester resin is more preferable.

Here, as engineering plastics,
For example, polyimide (PI), polyamide (PA), polyamide imide (PAI), polyphenylene oxide (PFO),
Polyphenylene ether (PPE), polyacetal (PO
M), polyether sulfone (PES), polyallyl sulfone (PAS), polyphenylene sulfide (PPS), polyetherimide (PEI), polybenzimidazole (PB
I), polyimidazopyrone (PIP), polyetheretherketone (PEEK), polyparabanic acid (PPA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc., among which PES, PEEK and PET are preferred .

Further, with the aromatic polyester resin, the general formula is (Wherein X is a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms, a group selected from —O—, —S—, —SO ₂ — and —CO—, and R and R ′ are C1-C20 alkyl, allyl,
Aralkyl, alkoxyl, allyloxyl, and allylalkoxyl groups, substituents thereof, monovalent groups selected from halogens and mixtures thereof, p and q are p + q = 0 to 4; m and n are 0 or 1; In the case of 1, n = 1), any synthetic resin may be used.
Above all, part or all of the formula (I) is represented by the following general formula (Where X, m, and n are the same as those in the formula (I), and R _{1 to} R _{4 each} have 1 to 1 carbon atoms.
4 represents a monovalent group selected from an alkyl group, an alkoxyl group, a phenyl group and a halogen atom), and more preferably an aromatic dicarboxylic acid component in the formula (II):
The molar ratio is (10/0 to 7/3), preferably 9/1 (terephthalic acid / isophthalic acid) and the molar ratio is 2/1 (bisphenol A / 3,3 ', 5,5 'Tetramethylbisphenol F). The molecular weight of the aromatic polyester resin used in the present invention is not particularly limited, but is generally 50,000 to 150,000, preferably 60,000 to 130,000.

Further, these aromatic polyester-based resins are polymers or copolymers of terephthalic acid and / or isophthalic acid and one or more bisphenols or bisphenols and a small amount of a divalent compound. It can also be obtained by a mixture. As the copolymer, for example, the aromatic dicarboxylic acid is a single or mixed component of terephthalic acid and isophthalic acid.

Preferred examples of the bisphenol component include 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane and 2,2-bis (3,5-di-sec-butyl-4-hydroxyphenyl). Propane, 2,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, bis (3,5
-Dimethyl-4-hydroxyphenyl) methane, 1,1-
Bis (3,5-dimethyl-4-hydroxyphenyl) ethane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) cyclohexane, bis (3,5-dimethyl-4-hydroxyphenyl) Ketone, bis (3,5-dimethyl-4-
(Hydroxyphenyl) ether, bis (3,5-dimethyl-4-hydroxyphenyl) sulfide, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) hexafluoropropane, 2,2-bis (3,5-dimethoxy-4-hydroxyphenyl) propane, bis (3,5-dimethoxy-4-hydroxyphenyl) methane, 2,2-bis (3-
Methoxy-4-hydroxy-5-methylphenyl) propane, bis (3-methoxy-4-hydroxy-5-methylphenyl) methane, bis (3,5-diphenyl-4-hydroxyphenyl) methane, 2,2-bis ( 3,5-diphenoxy-4-hydroxyphenyl) propane, bis (3-
Phenoxy-4-hydroxy-5-methyl) methane, 4,
4'-dihydroxy-3,3 ', 5,5'-tetramethylbiphenyl, 4,4'-dihydroxy-3,3', 5,5'-tetraethylbiphenyl, bis (4-hydroxy-3-methylphenyl ) Sulfone, bis (4-hydroxy-3,5-dimethylphenyl) sulfone, bis (4-hydroxy-3-ethylphenyl) sulfone, bis (4-hydroxy-3,5
-Diethylphenyl) sulfone, bis (4-hydroxy-3,5-dimethoxyphenyl) sulfone, bis (4-hydroxy-3,5-diethoxyphenyl) sulfone and the like.

Bisphenol components having a substituent at the 3,5-position include 4,4'-dihydroxydiphenyl and bis (4-
It can be used in a mixture with (hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, hydroquinone, resorcin and the like. It is also possible to use bisphenolic dyes such as phenolphthalein, fluorescein, naphthophthalein and thymolphthalein.

The thermoplastic film raw material to be subjected to the preheating step may be a film obtained by any method such as a hot melting method and a solution casting method, and among them, the solution casting method is preferable. Examples of the heat melting method include an extrusion method, a calender method and a press method, and the solution casting method includes:
For example, there are a solvent casting method and a sol casting method, and among them, the solvent casting method is preferable.

As described above, the film heat treatment apparatus obtained according to the present invention can produce an optically isotropic thermoplastic film efficiently and easily, which greatly contributes to the industry.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1 Methylene chloride solution of mixed acid chloride in which terephthalic acid dichloride and isophthalic acid dichloride have a molar ratio of 9: 1, and molar ratio of bisphenol A and 3,3 ', 5,5'-tetramethylbisphenol F A polyarylate resin having a Mw of 70,000 Tg at 215 ° C. was produced from a 3: 1 alkaline aqueous solution by an interfacial polymerization method.

180 parts by weight of this polyarylate resin was dissolved in 1000 parts by weight of methylene chloride to prepare a 15 wt% dope. This is dried in a film casting facility (40 ° C for 0.5 minutes, 60 ° C for 1 minute).
Minutes), and then dried on both sides with a tenter (150 ° C for 1 minute, 230
℃ 5 minutes) and heat fixation (250 ° C 3 minutes), about 75μ thickness 1
A completely dried polyarylate film (A) having a width of 100 mm was obtained.
The birefringence of this film was as shown in FIG. 3, and the portion of 20 nm or less was 50 mm or less.

Next, the polyarylate film (A) is
As shown in Fig.2 and Fig.2, a 15mm diameter far infrared heater was installed in the whole area of the both-side slow cooling process at a position 30mm from the grip part and 50mm above the film as an auxiliary heating source. Preheating temperature 255
C. 4 minutes, and in the film slow cooling step, the inlet temperature at the center of the film is 255.degree. C., the outlet temperature is 180.degree. C., the inlet temperature near the auxiliary heating device is 265.degree. Was. Further, the curing process was performed at 180 ° C. for 1 minute to obtain a film having a width of 1000 mm.

The width of this film with a birefringence of 20 mm or less is 810 mm (birefringence 2
0 nm or less, yield: 81%). Table 1 shows the results.

Example-2 Polyarylate film (A) used in Example-1
And a film having a width of 1000 mm was obtained in exactly the same manner as in Example 1 under the conditions shown in Table 1. Table 1 shows the conditions and results.

Example 3 180 parts by weight of a polycarbonate resin (Mw 60,000, Tg 149 ° C.) obtained from bisphenol A and phosgene by an interfacial polymerization method was dissolved in 1,000 parts by weight of methylene chloride to obtain a 15 wt% tope. This was dried in a casting facility in exactly the same manner as in Example 1 (40 ° C for 0.5 minute, 60 ° C for 1 minute), and further heated in a tenter facility (130 ° C for 1 minute, 170 ° C for 5 minutes) and heat-fixed ( 180 ℃ 3
) To obtain a completely dried polycarbonate film (B) having a thickness of about 75 µm and a width of 1100 mm. The birefringence of this film is the third
As shown in the figure, the portion of 20 nm or less was 30 mm or less.

Next, this polycarbonate film (B) was treated in the same manner as in Example 1, and a continuous film heat treatment apparatus having an auxiliary heating device (far-infrared heater) shown in FIGS. In the film preheating temperature of 187 ° C for 5 minutes, and in the film gradual cooling step, the inlet ambient temperature at the center of the film is 187 ° C, the outlet temperature is 130 ° C, the inlet temperature near the auxiliary heating device is 195 ° C, and the outlet temperature is 140 ° C.
During this time, cooling was performed in 3 minutes. In addition, 130
C. for 1 minute to obtain a film having a width of 1000 mm.

The width of birefringence of less than 20nm is 730mm, birefringence
At 2.0 nm or less, the yield was 73%. Table 1 shows the results.

Example-4 Polyarylate film (A) used in Example-1
A 15-mm diameter far-infrared heater with a diameter of 15 mm was installed as a supplementary heating source as shown in FIGS. 1 and 2 at a position 30 mm from the grip and 50 mm above the film, at both ends of the slow cooling / rapid cooling process. 1050mm continuous film heat treatment equipment, film preheating temperature 255 ° C for 3 minutes, and in the film slow cooling process, inlet temperature 255 ° C, outlet temperature 230 ° C in the center of film and inlet temperature 267 ° C, outlet temperature 250 near auxiliary heating device. C., during which time slow cooling took place in one minute. Next, in the film rapid cooling process, the inlet temperature at the center of the film is 230 ° C, the outlet temperature is 200 ° C, and the inlet temperature near the auxiliary heating device is 250 ° C and the outlet temperature is 215 ° C. went. Further, the curing process was performed at 200 ° C. for 1 minute to obtain a film having a width of 1000 mm. Birefringence of this film
The width of 20 nm or less was 780 mm (birefringence: 20 nm or less, yield: 78%). Table 1 shows the results.

Comparative Examples 1 and 2 A film was obtained in exactly the same manner as in Example 1 except that the temperature conditions were changed as shown in Table 1 (Comparative Example 1). Example except that no auxiliary heating device is used
A film was obtained in exactly the same manner as in the method shown in FIG. 1 (Comparative Example-2).

Here, Tg is the glass transition temperature, which is the temperature at which discontinuity occurs when the first-order thermodynamic derivative is plotted against temperature, and is the density, specific volume, specific heat, acoustic coefficient or refractive index. Obtained from relationships.

The values measured and evaluated by the following methods were used for physical properties.

(1) Glass transition temperature (Tg) Measured using a DSC (differential scanning calorimeter) type II manufactured by PerkinElmer. That is, DSC of sample polymer 10mg
The sample was set in an apparatus, the temperature of the sample was raised from room temperature at 10 ° C./min, and the glass transition point was measured.

(2) Film temperature Measured with a contact surface thermometer manufactured by IRON.

(3) Optical isotropic / optical anisotropy MOA-200 microwave molecular orientation meter from KS Systems
It was measured using a type 1A. That is, the index MOR value representing the irregularity of the molecule is measured, and the smaller the value is, the more the orientation of the molecule is irregular, that is, the molecule is optically isotropic. It is regular, that is, optically anisotropic.

(4) Birefringence Polarizing microscope (OPTIPHOT-POL) of Nippon Kogaku Kogyo Co., Ltd.
Was measured by the Senarmont compensator method.

When this value is 20 nm or less, it is optically isotropic, and when it exceeds this value, it is optically anisotropic.

(5) Dimensional stability The dimensional stability at 180 ° C. for 30 minutes was evaluated as follows using a stress-strain measuring device (TMA) TSA-30 manufactured by Shimadzu Corporation.

And

〔The invention's effect〕

As described above, the molded product obtained by the film heat treatment apparatus of the present invention efficiently and easily produces an optically isotropic thermoplastic film, and greatly contributes to the industry. .

[Brief description of the drawings]

FIG. 1 and FIG. 2 are examples of a schematic view of an apparatus used for carrying out the present invention. FIG. 1 is a plan view and FIG. 2 is a side view. The numbers in the figure are as follows. 1: Preheating step area, 2: Cooling step area 3: Curing step area, 4: Auxiliary heating device 5: Film holder, 6: Film Fig. 3 shows the birefringence of the film obtained by the conventional device in the width direction This is one example shown in FIG. FIG. 4 is an example illustrating the birefringence of a film obtained by the apparatus of the present invention in the width direction.

Claims (7)

(57) [Claims] 1. A film heat treatment apparatus for producing a thermoplastic film having optically isotropic properties: (a) a preheating step of heating the film to Tg or more; and (b) a step of cooling the film. At least one end of the film is heated under the condition that the cooling rate is controlled at a rate of 1 ° C./sec to 0.01 ° C./sec at least in a temperature range of (Tg + 10) ° C. to (Tg−15) ° C. And a cooling step provided with a heating device. 2. In the preheating step, the film is treated with (Tg
The film heat treatment apparatus according to claim 1, wherein the film is preheated to + 35 ° C or higher. 3. The film heat treatment apparatus according to claim 1, wherein the film cooling atmosphere temperature in the cooling step is (Tg + 50) ° C. to (Tg−100) ° C. 4. The film heat treatment apparatus according to claim 1, wherein both ends of the film are supplementarily heated in the cooling step. 5. The film heat treatment apparatus according to claim 1, wherein in the cooling step, the film auxiliary heating temperature is higher than the ambient temperature by 2 to 100 ° C. 6. The film heat treatment apparatus according to claim 1, wherein the resin of the film is an aromatic polyester resin. 7. The method according to claim 1, wherein the aromatic polyester resin is (Wherein X is a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms, a group selected from —O—, —S—, —SO ₂ — and —CO—, and R and R ′ are carbon atoms. Alkyl, allyl, aralkyl, alkoxyl, allyloxyl and allylalkoxyl groups of the formulas 1 to 20, other substituents, monovalent groups selected from halogens and mixtures thereof, p and q are p + q = 0 to 0
Integer of 4, m and n are 0 or 1, provided that when m = 1, n =
7. The film heat treatment apparatus according to claim 6, which is the item 1).