JP2001212868A - Polycarbonate resin film for insert molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polycarbonate resin film for insert molding having a die line almost not seen after insert molding. SOLUTION: In the polycarbonate resin film for insert molding, a rugged difference ΔDt of the die line of the film and a width DW of the die line satisfy following formulae (1) and (2) of 0.1<=ΔDt<=0.5 and 1<=DW<=500, wherein ΔDt is the rugged difference (μm) of the film, and DW is a width (μm) of the die line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate resin film for insert molding in which a die line is hardly seen after insert molding and a polycarbonate resin film for insert molding having excellent insert moldability.
More specifically, the present invention relates to a polycarbonate resin film which is excellent in workability, is suitable for insert molding applications, has excellent surface properties, has low elasticity at high temperatures, and has excellent dimensional stability, and a molded product thereof.

[0002]

2. Description of the Related Art Polycarbonate resins are widely used in various fields by taking advantage of their features such as low cost, light weight, and excellent transparency, moldability, optical properties, heat resistance, workability, and mechanical strength. It is also used as a film and is widely used for printing, thermoforming, vacuum forming, insert forming, metal vapor deposition, sputtering, etc., but in recent years the production speed has increased with the progress of processing techniques such as printing and thermoforming. The processing conditions are becoming stricter due to the higher speed and the higher speed due to the shorter processing time.

Conventionally, when a polycarbonate resin is melted and extruded into a film and manufactured using a plurality of cooling rolls, the melt-extruded sheet is received as it is by a single cooling roll without being sandwiched and pressed. When the film manufactured by the single-sided touch method is used in insert molding, the die line of the film on the surface of the molded product has a problem in appearance.

[0004] The die line is a pattern in which the molten resin extruded from the T-die adheres to the metal wall surface of the T-die as a cleaning mark, and the resin line adheres to the lip opening of the T-die. The irregularities of these die lines are about 0.05 to 1.0 μm and their widths are made up of peaks and valleys of about 1 to 1000 μm.

[0005] In particular, a polycarbonate resin film used for insert molding is usually used after at least one surface is subjected to surface processing such as printing or hard coating.
When this surface-processed film is insert-molded,
The appearance of the surface of the molded product is prominent because the die line emerges or is amplified by the surface processing, so when used for automobile windows, display windows of mobile phones, display parts of calculators / copiers, etc., the subject or characters are distorted. Visible in That is, problems such as distortion of the perspective image occur, which is not preferable, and a problem that the value as a product is greatly reduced has occurred.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polycarbonate resin film for insert molding which has almost no apparent die line when used for insert molding and which has excellent dimensional stability. Is to provide.

The inventor of the present invention has made intensive studies to solve the conventional technique. As a result, the sheet material extruded into a film shape by melting the polycarbonate resin is received by a single cooling roll without being pinched and pressed as it is. When manufacturing by the single-sided touch method, pay attention to the T-die to be melt-extruded, use the T-die of the edge of the lip opening, which is the tip portion, and the surface roughness Ra in a specific range, and set the temperature and temperature during cooling. Focusing on the fact that shrinkage occurs at the time of secondary molding due to drawing by drawing, it has been found that the above-mentioned problems can be achieved by controlling the rotating speed and temperature of the drawing roll within a certain range, thereby achieving the present invention.

[0008]

SUMMARY OF THE INVENTION The present invention is unevenness difference of die line of the polycarbonate resin film △ D _t and the width D _w of the die line is represented by the following formula (1) and the following formula _{(2) 0.1 ≦ △ D t} ≦ 0 ... (1) 50 ≦ D _w ≦ 500 (2) [wherein ΔD _t is the difference in unevenness of the film die line (μ
m) and Dw relate to the polycarbonate resin film for insert molding which satisfies the width of the die line (μm)]. The present invention also relates to a polycarbonate resin insert-molded product characterized in that the above-mentioned polycarbonate resin film is used as a film to be inserted into a mold when insert-molding a polycarbonate resin.

The polycarbonate resin used in the present invention is obtained by reacting a dihydric phenol with a carbonate precursor by an interfacial polycondensation method or a melting method. Representative examples of dihydric phenols include 2,2-bis (4-
Hydroxyphenyl) propane [commonly known as bisphenol A], 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (3-methyl-4-hydroxyphenyl) ) Propane, 2,2-bis (3,5-dimethyl-)
Examples thereof include 4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfide, and bis (4-hydroxyphenyl) sulfone. Of these, bisphenol A is preferable. These dihydric phenols can be used alone or in combination of two or more.

As the carbonate precursor, carbonyl halide, carbonate ester or haloformate is used, and specific examples include phosgene, diphenyl carbonate and dihaloformate of dihydric phenol.

In producing the polycarbonate resin by reacting the dihydric phenol with the carbonate precursor by an interfacial polycondensation method or a melting method, a molecular weight modifier,
A catalyst or the like can be used as needed. Further, the polycarbonate resin may further contain additives such as release agents such as esters or partial esters of polyhydric alcohols and fatty acids, heat stabilizers such as phosphites, phosphates and phosphonates, and benzotriazole. UV absorbers such as lactophenone, acetophenone and salicylic acid esters, antistatic agents, coloring agents, brightening agents, flame retardants and the like may be added. Further, the polycarbonate resin may be a branched polycarbonate resin obtained by copolymerizing a trifunctional or higher polyfunctional aromatic compound, or a polyester carbonate resin obtained by copolymerizing an aromatic or aliphatic bifunctional carboxylic acid, Further, a mixture of two or more of the obtained polycarbonate resins may be used.

The molecular weight of the polycarbonate resin is preferably 10,000 to 100,000, more preferably 15,000 to 35,000 in terms of viscosity average molecular weight (M). Polycarbonate resin having such a viscosity average molecular weight,
Sufficient strength is obtained, and the melt fluidity during molding is also favorable, which is preferable. The viscosity average molecular weight referred to in the present invention is 2 g of polycarbonate resin 0.7 g in 100 mL of methylene chloride.
The specific viscosity (η _sp ) obtained from the solution dissolved at 0 ° C. was obtained by inserting it into the following equation. η _sp /c=[η]+0.45×[η] ² c (where [η]
Is the intrinsic viscosity) [η] = 1.23 × 10 ⁻⁴ M ^0.83 c = 0.7

[0013] The polycarbonate resin film for insert molding of the present invention has an irregularity difference ΔD of a die line of the film.
_t (μm) and the width D _w (μm) of the die line satisfy the following expression. 0.1 ≦ △ D _t ≦ 0.5 (1) 1 ≦ D _w ≦ 500 (2)

The reason that the difference ΔD _t between the concavities and convexities of the film die line and the width D _{w of the} die line satisfy the above formulas (1) and (2) is that the die line of the molded product is almost conspicuous when the film is used for insert molding. And the appearance of the obtained molded article becomes good. In addition, having this appropriate surface property has the advantage that the film can be mounted smoothly during insert molding, and an insert molded product without wrinkles can be obtained.
On the other hand, the above formula (1), in the case of using the deviant film range (2), the appearance of the insert molding, that is, die lines of the film appearance conspicuous amplifies defect occurs, △ D _t and D the value of _w is △ D _t is 0.2~0.4μm is preferable. D _w is preferably 1~300μm, 50~30
0 μm is more preferred. Most preferably 100-300
μm.

The appearance of the die line differs depending on the shape. For example, even with the same △ D _t , a gentle curve with a large D _w is not noticeable, and a sharp curve with a small D _w is noticeable. Therefore,
When the ratio of ΔD _t to D _w is R (ΔD _t / D _w ), 0.000
2 to 0.5 is preferable, and 0.0007 to 0.01 is more preferable. Most preferably, it is 0.001 to 0.004.

Further, the film of the double-sided touch product which is pinched and pressed at the time of molding does not have a die line but has a gear mark. .

The polycarbonate resin film for insert molding of the present invention has a heat expansion and contraction rate (%) S _TD in the width direction at a heating temperature of 160 ° C. and a heat expansion and contraction rate (%) S _{MD in the} extrusion direction.
Are preferably those satisfying the following expression (3). 0.3 ≦ _STD / _SMD ≦ 3 (3) When the ratio of _STD / _SMD satisfies the above ratio, it is necessary to maintain the ratio of the vertical and horizontal heating expansion / contraction ratios at the time of insert molding in a substantially balanced state. Uniform stress is applied to the film without sagging and biasing of shrinkage stress. Therefore, the occurrence of film wrinkles during insert molding can be suppressed, and the appearance of the insert molded product can be improved. On the other hand, if it deviates from this range, the contraction stress is biased, the contraction in one of the extrusion direction or the width direction of the obtained film is further reduced in the other direction, and the expansion and contraction balance is broken, and the appearance of the insert molded product is reduced. It becomes defective (wrinkles). The ratio of S _TD / S _MD is preferably from 0.4 to 2, more preferably from 0.5 to 1.1.

_STD and _SMD satisfy the following equations (4) and (5), respectively. _{-5.0 ≦ S TD ≦ -0.2 ... (} 4) -5.0 ≦ S MD ≦ -0.2 ... (5) S TD and S _MD is that with moderate heating expansion ratio, insert molding The stretching stress generated therein can keep the film in an appropriate tension state. This heat expansion / contraction rate is −5.0.
%, Expansion and contraction are large, and poor appearance occurs. On the other hand, when the content exceeds -0.2%, the film is stretched by heating, so that the appearance is poor and it is difficult to put the film to practical use, and the object of the present invention cannot be achieved.

In order to produce the polycarbonate resin film of the present invention, a molten polycarbonate resin extruded from a T-die is cooled by a plurality of mirror cooling rolls of a one-sided touch type to form a film. Its thickness is 0.05 ~
0.5 mm is preferred. The device used at this time does not need to be a special device, and any device used for film formation, film or sheet production is arbitrarily adopted.

Methods for reducing the die line of the polycarbonate resin film include adjusting the temperature of the molten resin during extrusion molding and selecting the melt viscosity, or the air gap between the cooling roll and the T-die, and the falling of the molten resin film in contact with the cooling roll. Examples include a method of adjusting the position or applying a high voltage to the molten polycarbonate resin film in contact with the cooling roll, and a method of setting the lip edge R and the surface roughness Ra of the T die to be used in a specific range. Among them, a method in which the lip edge R and the surface roughness Ra of the T-die used are in specific ranges is preferable.

The T-die used has a lip edge R
Is 0.005 to 0.05 mm and the surface roughness Ra is 0.0
It is preferably not more than 05 μm. Lip edge R
Refers to the radius of the corner portion where the lip edge is chamfered. If the lip edge is less than 0.005 mm, the lip opening becomes a sharp cutting edge, and the possibility of breakage during cleaning or assembling the T-die is increased, which is not preferable. In addition, the R of the lip edge of a T die generally used in the related art is 0.2 to 0.3.
The T-die has a problem that the polycarbonate resin melted by continuous molding for a long time adheres to the lip opening and a die line is observed on the film surface. By adopting the following lip edge, the resin does not easily adhere and the die line is not observed on the film surface. In addition, it is desirable that the lip edge is symmetrical, and if symmetric, the molten resin film discharged from the lip mouth comes into contact with the roll without waving when falling, causing a problem that undulation occurs on the film surface. Difficult and preferred.

Further, the surface roughness Ra of the lip edge of the T-die is preferably 0.005 μm or less, more preferably 0.0001 to 0.005 μm, and still more preferably 0.0002 to 0.003 μm. Preferably it is 0.0003 to 0.001 μm. 0.005μm
When it is below, the die line appearing on the surface of the obtained polycarbonate resin film becomes pale and the appearance becomes good.

Generally, a T-die is manufactured by processing a metal bar with a cutting machine. The lip edge R portion of the T-die used in the present invention and a portion having a predetermined surface roughness Ra are subjected to very precise polishing as a surface finish, and further subjected to plating such as chrome plating to prevent corrosion. Is done. The surface roughness of the lip edge of the T-die in the present invention is the surface roughness of the edge portion from the lip opening to about 1 cm. The surface roughness of the lip edge portion can be substituted by a value obtained by measuring the surface roughness of the flat portion on the inner surface of the lip opening from the lip edge portion subjected to the same surface finishing treatment as the lip edge portion.

The method for producing the film of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a film manufacturing apparatus suitable for the present invention. In the figure, 1 is a T die, 2 is a first cooling roll, 3 is a second cooling roll, 4 is a third cooling roll, 5 is a pair of take-off rolls, and all of the first to third cooling rolls are on the surface thereof. Has a mirror finish, inside which a heat medium circulates so that the temperature can be controlled. FIG. 2 is a schematic view of a lip edge R portion 6, 7 of a T-die showing an example of manufacturing a film having a die line in a specific range of the present invention.

First, a molten polycarbonate resin is extruded from the T-die 1 into a sheet. No special conditions are required for melt extrusion at this time, and ordinary conditions for melt extrusion of a polycarbonate resin sheet are arbitrarily adopted. Next, the extruded sheet-like material is kept as it is on the first cooling roll 2.
After being brought into close contact with the central second cooling roll 3 while being supplied between the second cooling roll 3 and the second cooling roll 3, the second cooling roll 3 is taken over by the third roll 4 at the other end, and is taken up by a pair of take-up rolls 5.

At this time, it is preferable that the rotation speed of the third cooling roll 4 with respect to the second cooling roll 3 is 1.001 to 1.015 times. When the rotation speed of the third cooling roll 4 with respect to the second cooling roll 3 is maintained in this range, a molded product having a good balance of heat expansion and contraction and having no wrinkles during insert molding can be obtained.

Further, the temperature of the first cooling roll 2 is 1
30 to 145 ° C., the temperature of the second cooling roll 3 is 135 to 1
It is preferable that the temperature of the third cooling roll 4 is set to 145 to 155 ° C. These first to third cooling rolls 2
The temperature control of (4) to (4) can be easily performed by the conventional roll temperature control means.

The above-mentioned polycarbonate resin film of the present invention can be suitably used as a film to be inserted into a mold at the time of insert molding. Such a film is usually used after at least one surface is surface-treated. Examples of the surface processing include printing, hard coating, and the like, and the processing layer may be a single layer or a multilayer. The thickness of this layer is generally between 0.1 and 20 μm. In the case of a film processed on one side, the processed surface (the desired surface in the case of double-sided processing) is set to the mold surface side, and the film is set. Next, a thermoplastic resin is injection molded.

Examples of the thermoplastic resin include polyamide resin, polyimide resin, polyetherimide resin, polyurethane resin, polyphenylene ether resin,
Polyphenylene sulfide resin, polysulfone resin, polyethylene, polyolefin resin such as polypropylene,
Polyester resin such as polyethylene terephthalate, polybutylene terephthalate, amorphous polyarylate resin, polystyrene resin, acrylonitrile / styrene copolymer (AS resin), acrylonitrile / butadiene /
Resins such as a styrene copolymer (ABS resin), a polymethacrylate resin, a phenol resin, and an epoxy resin are exemplified, and a polycarbonate resin is preferred.

Further, the above-mentioned polycarbonate resin film of the present invention can be used as a film to be inserted into a mold especially when insert-molding a polycarbonate resin. Polycarbonate resin is usually 280
Since injection molding is carried out at a molding temperature of at least ℃, high heat resistance is also required for a film to be inserted into a mold, and the polycarbonate resin film of the present invention preferably has a small heat expansion and contraction rate at a high temperature. ,Also,
The thickness of the film is preferably in the range of 0.05 to 0.5 mm, more preferably in the range of 0.1 to 0.5 mm, and particularly preferably in the range of 0.2 to 0.4 mm.

The polycarbonate resin film produced by the present invention is widely used for insert molded articles such as electric parts and automobile parts by utilizing its properties. Specifically, various window materials for electric parts, that is, vehicles (construction machinery) , Cars, buses,
It is also suitable for glazing products for window materials such as Shinkansen trains and train cars, various nameplates, photographic covers, front plates of projection televisions and plasma displays, and Fresnel lens applications.

[0032]

The present invention will be further described with reference to the following examples. In addition, the evaluation in an Example followed the method shown below. (1) Method for confirming die line A polycarbonate resin film is hung at a position 5 m from a projector with a 100 V halogen lamp (Elmo Co., Ltd.), and an image reflected on a white plate 10 cm behind the position is visually observed. The presence or absence was checked. When there was a die line, it was indicated by x, and when it was not, it was indicated by o. (2) Measurement of die line unevenness and width The die line with the darkest shadow confirmed by the above method is J
A stylus type surface roughness meter using the method of ISB0601 (Co., Ltd.)
(Manufactured by Tokyo Seimitsu) under the conditions of a cutoff of 0.8 mm and a measurement length of 4 mm, and the unevenness and width of the die line were measured by a baseline method. (3) Heat expansion ratio The heating expansion ratio test method of JIS K 6735 is applied mutatis mutandis.
The heating was performed at 60 ° C. × 40 minutes. (4) Appearance of Insert Molded Article The appearance (die lines, wrinkles, horizontal stripes) of the molded articles obtained by the insert molding obtained in Examples and Comparative Examples was visually determined. Good insert appearance after insert molding, ○, die line pattern is emphasized and noticeable, horizontal stripe pattern is noticeable, or insert film is distorted and wrinkles or slack due to wrinkles or molded products Those whose appearance was impaired such as warpage were indicated by x.

Examples 1 to 3 and Comparative Examples 1 to 3 A polycarbonate resin having a viscosity average molecular weight of 24,500 produced from bisphenol A and phosgene by an interfacial polymerization method was manufactured by using a production apparatus shown in FIGS. 120
Approximately 280 ° C using an extruder with a T-die lip
Table 1 shows the surface roughness Ra of the lip edge of the T die, the speed ratio of the third cooling roll to the second cooling roll, and the respective temperatures of the first to third cooling rolls. A polycarbonate resin film was formed while being set and cooled as described above, and was taken up by a take-off roll, and printing was performed on the obtained film. The printed film is mounted in an injection mold so that the printing surface is on the mold surface side, and insert molding is performed using a polycarbonate resin pellet (manufactured by Panlite L-1225 Teijin Chemicals) at a molding temperature of 310 ° C. went. Evaluate the physical properties of the obtained film, the appearance of the molded product after insert molding,
Table 2 shows the results.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

The die line of the present invention is hardly noticeable.
The polycarbonate resin film, which has excellent dimensional stability, makes the unevenness and width of the die line of the film within a specific range, so that the die line in the appearance after insert molding is almost inconspicuous, and the vertical and horizontal heat expansion and contraction rate of the film By setting the ratio to a specific range, the film can be kept in tension by the shrinkage stress generated during molding. Does not occur, and uniform stress is applied to the film.
Since the occurrence of film wrinkles during insert molding can be suppressed, it is suitably used as an insert film, and is extremely useful for an injection molded product by insert molding, and its industrial effect is exceptional.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an apparatus for producing a film of the present invention.

FIG. 2 is a view of a lip edge R portion of a T-die for producing a film of the present invention.

FIG. 3 is a measurement chart (mountain shape) of a die line of the polycarbonate resin film obtained in Example 1.

FIG. 4 is a measurement chart (valley shape) of a die line of the polycarbonate resin film obtained in Comparative Example 1.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 T die 2 First cooling roll 3 Second cooling roll 4 Third cooling roll 5 A pair of take-off rolls 6 Lip edge R 7 Lip edge R

Claims (5)

[Claims] 1. A unevenness difference of die line of the polycarbonate resin film △ D _t and die line width D _w of the following formulas (1) and the following formula _{(2) 0.1 ≦ △ D t} ≦ 0.5 ... (1) 1 ≦ D _w ≦ 500 (2) [wherein ΔD _t is the unevenness of the film die line (μ
m), Dw is the width of the die line (μm)]. 2. A thickness of 0.05 to 0.5 mm obtained by cooling a molten polycarbonate resin having a polycarbonate resin film extruded from a T-die with a cooling roll of a one-sided touch type.
The polycarbonate resin film for insert molding according to claim 1, which is: 3. The polycarbonate resin film for insert molding according to claim 1, wherein a heat expansion / contraction rate at a heating temperature of 160 ° C. satisfies the following formulas (3) to (5). _{0.3 ≦ S TD / S MD ≦} 3 ... (3) -5.0 ≦ S TD ≦ -0.2 ... (4) -5.0 ≦ S MD ≦ -0.2 ... (5) [ in the formula , _STD is the heat expansion and contraction rate in the width direction (%), _SMD is the heat expansion and contraction rate in the extrusion direction (%)] 4. The R of the lip edge is 0.005 to 0.0.
The polycarbonate resin film for insert molding according to any one of claims 1 to 3, which is produced by melt extrusion molding using a T-die having a thickness of 5 mm and a surface roughness Ra of 0.005 µm or less. 5. A polycarbonate resin insert, wherein a film to be inserted into a mold when producing an insert molded product using a polycarbonate resin is the polycarbonate resin film for insert molding according to any one of claims 1 to 4. Molding.