JP3119457B2 - Transparent film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent film, and more particularly to a transparent film comprising a methyl methacrylate copolymer and an aromatic polycarbonate. The transparent film obtained by the present invention has excellent transparency, and as a film having both characteristics of polymethyl methacrylate and aromatic polycarbonate, a reflection sheet, a marking film, a protective film such as a CD / LD, a retardation film. Used as a protective film for a polarizing plate.

[0002]

2. Description of the Related Art Conventional transparent films of poly (methyl methacrylate) have excellent properties such as weather resistance and surface hardness. However, these films have insufficient heat resistance and mechanical properties depending on the intended use. There is a need to improve the problems. In particular, since the film of polymethyl methacrylate is brittle, there is a problem that the film is easily broken by bending or impact.
On the other hand, aromatic polycarbonates, especially bisphenol A
Have excellent mechanical properties and heat resistance, but have insufficient surface hardness and weather resistance. Therefore, in order to obtain a transparent film having excellent characteristics of polymethyl methacrylate and aromatic polycarbonate, it is conceivable to mix both resins. It is known that a transparent and completely compatible film can be obtained when polymethyl methacrylate and polycarbonate of bisphenol A are mixed in tetrahydrofuran which is a common solvent and cast at an appropriate temperature. However, since the cloud point of the mixture of these two resins is about 180 ° C., they separate into two phases at high temperatures. Therefore, it is known that a transparent completely compatible film cannot be obtained by melt molding of polymethyl methacrylate and aromatic polycarbonate, and a blend of these two resins has pearl luster and is opaque. [J. Polym. Sci. , Polym. P
hys. ED. , 25, 1459 (1987)].

[0003] In order to improve the compatibility at high temperatures, attempts have been made to blend an aromatic polycarbonate with a methyl methacrylate copolymer into which various comonomer units have been introduced. For example, according to JP-A-63-256647,
It is described that a copolymer of methyl methacrylate and methacrylamide, a copolymer of methyl methacrylate and maleimide, and a polycarbonate of bisphenol A are melt-kneaded to give a transparent or slightly cloudy blend. However, since the methyl methacrylate copolymer described in these publications contains a nitrogen atom, when the blend is melt-molded, coloring is likely to occur, and the cloud point of the blend is not sufficiently high. There was a problem. On the other hand, Japanese Patent Laid-Open No.
According to Japanese Patent No. 749, a methacrylate unit and / or an acrylate unit having a carbocyclic group in an ester group is used as a comonomer unit of a methyl methacrylate copolymer, and if necessary, a styrene unit and / or α-methylstyrene are used. It has been proposed to use units together. However, even in the blend of the above copolymer and polycarbonate, the cloud point, heat resistance, and water absorption are not improved in a well-balanced manner. Is still not enough.

It has been reported that the introduction of another comonomer unit into poly (methyl methacrylate) can improve the compatibility with aromatic polycarbonates, especially at high temperatures. In reality, it has not been possible to obtain a film in which the above-mentioned problems of a film made of an aromatic polycarbonate and a film made of an aromatic polycarbonate are improved in a well-balanced manner.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a transparent resin comprising a methyl methacrylate copolymer and an aromatic polycarbonate, which has excellent mechanical properties, heat resistance, weather resistance and surface hardness. It is to provide a film.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that acrylic acid esters and / or methacrylic acid having an aromatic group substituted with methyl methacrylate and a halogen element. The present inventors have found that the above object can be achieved by a blend of a copolymer composed of an acid ester and an aromatic polycarbonate, and have completed the present invention.

That is, according to the present invention, the above-mentioned object is to provide 50 to 98% by weight of a methyl methacrylate unit, 2 to 50% by weight of a monomer unit represented by the following general formula (I) and other copolymerizable This is achieved by a polymer composition comprising a copolymer (A) comprising 0 to 25% by weight of α, β-unsaturated monomer units and an aromatic polycarbonate (B).

[0008]

Embedded image

[In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each represent a halogen atom or at least one of them.
One represents a halogen atom, and the other represents a hydrogen atom, a lower alkyl group or a lower alkoxyl group. ]

Hereinafter, the present invention will be described in detail. The copolymer (A) of the present invention contains, as essential components, a methyl methacrylate unit and a monomer unit represented by the following general formula (I).

[0011]

Embedded image

Wherein R ¹ represents a hydrogen atom or a methyl group, and R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each represent a halogen atom, or at least one of them.
One represents a halogen atom, and the other represents a hydrogen atom, a lower alkyl group or a lower alkoxyl group. ]

The halogen atom represented by R ² to R ⁶ in the monomer represented by the above general formula (I) includes, for example, a chlorine atom, a bromine atom and an iodine atom, and the lower alkyl group includes, for example, methyl And the lower alkoxyl group includes, for example, a methoxy group and an ethoxy group. Examples of the monomer represented by the general formula (I) include chlorophenyl methacrylate, dichlorophenyl methacrylate, trichlorophenyl methacrylate, tetrachlorophenyl methacrylate, pentachlorophenyl methacrylate,
Bromophenyl methacrylate, dibromophenyl methacrylate, tribromophenyl methacrylate, pentabromophenyl methacrylate, chlorophenyl acrylate, dichlorophenyl acrylate, trichlorophenyl acrylate, tetrachlorophenyl acrylate, pentachlorophenyl acrylate, bromophenyl acrylate, dibromophenyl acrylate, tribromophenyl acrylate Bromophenyl acrylate, pentabromophenyl acrylate and the like can be mentioned, and 2,4,6-tribromophenyl methacrylate is particularly preferably used.

The content of methyl methacrylate unit in the copolymer (A) is 50 to 98% by weight, preferably 50 to 98% by weight.
To 95% by weight, more preferably 50 to 90% by weight. In order to maintain good weather resistance and transparency which are characteristics of polymethyl methacrylate, the content is 5%.
It must be at least 0% by weight.

The copolymer (A) has the general formula (I)
Is 2 to 50% by weight, preferably 5 to 50% by weight, and more preferably 10 to 50% by weight.
５０50% by weight. If the content is less than 2% by weight, sufficient compatibility between the copolymer (A) and the aromatic polycarbonate (B) cannot be obtained, while if it exceeds 50% by weight, the strength characteristics of the copolymer (A) will be poor. Lower, which is not preferred.

Further, the polymer of the present invention may contain, in a range not impairing the effects of the present invention, 25% by weight or less of methyl methacrylate unit and α, other than the monomer unit represented by the general formula (I). It may contain β-unsaturated monomer units. Examples of the monomer constituting such a monomer unit include aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, and styrene whose nucleus is substituted by halogen. , Methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate,
2-ethylhexyl acrylate, lauryl acrylate, cyclohexyl acrylate, acrylates having 1 to 18 carbon atoms such as phenyl acrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, C2-C18 methacrylates such as phenyl methacrylate, acrylic acid, methacrylic acid, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, maleic anhydride, maleic imide, monomethyl maleate, monoethyl maleate, Monoisopropyl maleate, dimethyl maleate, diethyl maleate and the like can be mentioned. Of these, styrene and α-styrene are aromatic vinyl monomers, and acrylates and methacrylates are those having 1 to 12 carbon atoms and those having 2 to 12 carbon atoms, respectively. preferable.

The average molecular weight of the copolymer (A) of the present invention is not particularly limited, but is preferably 10,000 to 5,000,000, more preferably 50,000, from the viewpoint of strength characteristics and moldability. Those having a number average molecular weight in the range of １，1,000,000 are used.

The copolymers (A) are prepared by known processes for polymerizing α, β-unsaturated compounds, in particular by radical polymerization, for example by bulk, solution, suspension or emulsion polymerization.

Examples of the radical polymerization initiator used in the above polymerization include azo compounds such as azobisisobutyronitrile and azobis (γ-dimethylvaleronitrile), or benzoyl peroxide, cumyl peroxide, oxyneodecaine. Peroxy compounds such as noate, diisopropylperoxydicarbonate, t-butylcumyl peroxide, cumene hydroperoxide, t-butylhydroperoxide, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, etc. Is mentioned. Usually, a polymerization initiator is added in an amount of 0.05 to 0.5 wt.
The copolymer (A) can be obtained by polymerizing at a temperature of about 140 ° C. for 2 to 20 hours.

In order to control the molecular weight of the copolymer (A), it is convenient to use a chain transfer agent. Examples of the chain transfer agent include methyl mercaptan, ethyl mercaptan, isopropyl mercaptan, n-butyl mercaptan, t-butyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, ethyl thioglycolate, mercaptoethanol, and thiocaprolactane. -Β-naphthol, thiophenol and the like are used, and usually 0.005 to
Used in the range of 0.5% by weight.

The aromatic polycarbonate (B) used in the present invention includes, for example, 4,4-dihydroxydiphenylalkane-based polycarbonate, and bisphenol-A polycarbonate is particularly preferred. The aromatic polycarbonate is preferably from 10,000 to 500,000, more preferably from 1 to 50, from the viewpoint of meltability.
Those having a number average molecular weight in the range of 0000 to 60,000 are used.

As shown in the following examples, the transparent film of the present invention is very useful from the viewpoint of controlling the birefringence even when the ratio of one polymer is small. The mixing ratio with (B) is in the range of 0.1 / 99.9 to 99.9 / 0.1 by weight, and preferably in the range of 2/98 to 98/2. The thickness of the transparent film is usually 0.01 to 1 mm, preferably 0.01 mm.
5 to 0.5 mm.

The method for mixing the copolymer (A) and the aromatic polycarbonate (B) is not particularly limited, and a usual method can be used. For example, a method of melt-mixing using a Brabender mixer or the like. Is adopted. At the time of mixing, for example, an antioxidant, an ultraviolet absorber or the like can be added, and another component polymer that does not impair the properties of the transparent film of the present invention can also be mixed.

The method for forming the transparent film of the present invention is not particularly limited, and a usual method can be used.
Melt molding or a method in which both polymers are dissolved in a common solvent such as tetrahydrofuran to form a cast film is employed. The film thus produced can be further uniaxially or biaxially stretched. Stretched films are preferable because mechanical properties and the like can be further improved as compared with unstretched films.

[0025]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the examples, “parts” means “parts by weight” unless otherwise specified. Each property value was measured according to the following method.

Number average molecular weight: measured by GPC (in terms of polystyrene) using THF as a solvent.

Glass transition temperature (Tg): DSC (mett
ler DSC 20) in nitrogen at a heating rate of 10 ° C./min.

Light transmittance: The total light transmittance was measured by a integrating haze meter using a sample molded to a thickness of 2 mm by a hot press.

Birefringence: Press molded thickness 0.1 m
m, width 10 mm, length 60 mm using a test piece, 130
Stretching speed 10cm / min in silicone oil bath at ℃
After stretching to a stretching ratio of 1.2, the film was rapidly cooled in ice water to prepare a stretched film. The birefringence was measured using an automatic birefringence meter (manufactured by Mizojiri Optical Industry Co., Ltd.).

Surface hardness: Rockwell hardness was measured according to JIS Z2245.

Young's modulus and elongation at break: 70 mm × 20 mm × by autograph (manufactured by Shimadzu Corporation).
It measured using the test piece of 0.1 mm. Strain rate is 1mm
/ Min.

Bending test: The state after bending the test piece by 180 degrees was visually observed and evaluated by the following symbols. ○ ・ ・ ・ ・ ・ ・ Bendable (no whitening) △ ・ ・ ・ ・ ・ ・ ・ Slowly bendable (streaks occur but do not break) × ・ ・ ・ ・ ・ ・ ・ Break when bent

Synthesis Example 1 70% by weight of methyl methacrylate, 20% by weight of 2,4,6-tribromophenyl methacrylate, 10% by weight of cyclohexyl methacrylate, 0.1 PHR of lauroyl peroxide and 0.2 of n-octyl mercaptan
100 parts of a monomer mixture composed of PHR and ion-exchanged water 9
200 parts of an aqueous solution consisting of 9.75% by weight, 0.05% by weight of poly (polymethacrylate) and 0.2% by weight of sodium sulfate are charged into a 100-liter pressure-resistant polymerization tank equipped with a jacket, and the jacket is stirred under N ₂ atmosphere. The polymerization was started at a polymerization temperature of 75 ° C. through warm water. Three hours after the start of the polymerization, the temperature was raised to 120 ° C. through steam through the jacket, and the temperature was further maintained for one hour to complete the polymerization. The number average molecular weight of the obtained copolymer is 5.34 × 10 ⁴ ,
Its Tg was 117 ° C.

Examples 1 to 5 The copolymer shown in Synthesis Example 1 was used as the copolymer (A).
Using Panlite L-1250 (polycarbonate of bisphenol A, number average molecular weight 20,000) manufactured by Teijin Chemicals Ltd. as an aromatic polycarbonate, agitated at 250 ° C. and 20 rpm with a plastograph (manufactured by Brabender). Kneaded at speed for 10 minutes. The obtained blend was press-molded at 250 ° C. and 100 mm × 100 mm ×
0.1mm film and 100mm x 100mm x
A 2 mm sheet was prepared and used for various measurements. Table 1 shows the measurement results of Tg, light transmittance, surface hardness, Young's modulus, and elongation at break. 7 to test the flexibility of the film
Table 1 also shows the results of a 180 ° bending test performed on a test piece of 0 mm × 20 mm × 0.1 mm. The appearance of the test pieces was colorless and transparent for all the test pieces. The Tg (117 ° C.) of the polymer shown in Synthesis Example 1 was measured in the same manner as the Tg of the blends of Examples 1 to 5, and L-1250.
Only one appears at a temperature between Tg (151 ° C.) and the temperature varies according to the mixed composition.
It can be seen that all the blends are completely compatible systems.

[0035]

[Table 1]

Comparative Examples 1-3 Films and sheets molded from the polymer of Synthesis Example 1, L-1250, and a methyl methacrylate resin parapet H1000B manufactured by Kuraray Co., Ltd. in the same manner as in Examples 1-5, respectively, were subjected to Tg, light Results of measuring transmittance, surface hardness, Young's modulus and elongation at break, and Examples 1 to 5
Table 2 summarizes the results of the 180-degree bending test performed in the same manner as in the above. From the above results, the transparent film of the present invention improves the problems of the conventional polymethyl methacrylate film and the aromatic polycarbonate film, and has balanced mechanical properties and heat resistance.
It turns out that it has surface hardness.

[0037]

[Table 2]

Example 6 Using the polymer of Synthesis Example 1 and L-1250, kneading and molding were carried out in the same manner as in Example 1 at the weight ratios shown in Table 3 and further stretched to prepare a film, which was birefringent. Was measured. Table 3 shows the measurement results. Thus, it can be seen that the polymer composition of the present invention can control birefringence by changing the blend composition, and can be a material having different birefringence at the same stretching ratio. Further, in a blend composition range in which the amount of polycarbonate is small, there is a composition in which the birefringence becomes 0, and therefore, it is very useful.

[0039]

[Table 3]

[0040]

As described above, the transparent film of the present invention has more balanced mechanical properties, heat resistance, and surface properties than conventional films made of polymethyl methacrylate and films made of aromatic polycarbonate. Has hardness. The birefringence can be controlled by changing the blend composition, and a non-birefringent film can be obtained.
Because of the above-mentioned features, the transparent film of the present invention is useful as a reflection sheet, a marking film, a CD / LD protective film, a retardation film, a polarizing plate protective film, and the like.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI-29L 7:00 (72) Inventor Koji Arakawa 2-28 Kurashiki-cho, Nakajo-cho, Kitakanbara-gun, Niigata Kuraray Co., Ltd. (72) Invention Person Teruo Hasegawa 2-28 Kurashiki-cho, Nakajo-cho, Kitakanbara-gun, Niigata Inspector of Kuraray Co., Ltd. Kimitaka Murakami (56) References JP-A-5-9359 (JP, A) JP-A-1-294719 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 5/18 CEY B29C 55/02 C08L 33/12 C08L 69/00

Claims (1)

(57) [Claims] 1. Methyl methacrylate unit of 50 to 98% by weight, represented by the following general formula (I): [Wherein R ¹ represents a hydrogen atom or a methyl group, R ^2, R
³ , R ⁴ , R ⁵ and R ⁶ each represent a halogen atom, or at least one of them represents a halogen atom, and the other represents a hydrogen atom, a lower alkyl group or a lower alkoxyl group. ] The monomer unit 2 represented by
A copolymer (A) consisting of 0 to 50% by weight, and 0 to 25% by weight of another copolymerizable α, β-unsaturated monomer unit;
A transparent film comprising an aromatic polycarbonate (B).