KR20180103350A - Poly(amide-imide) copolymer and polymer film - Google Patents

Abstract

The present invention relates to a poly(amide-imide) copolymer and a film containing the same which can realize high scratch resistance and weather resistance by including specific repetition units with predetermined content.

Description

POLY (AMIDE-IMIDE) COPOLYMER AND POLYMER FILM < RTI ID = 0.0 >

The present invention relates to a poly (amide-imide) copolymer and a polymer film, and more particularly to a poly (amide-imide) copolymer and a polymer film having mechanical properties such as high scratch resistance and high transparency, And a film containing the same.

The aromatic polyimide resin is a polymer having mostly an amorphous structure and exhibits excellent heat resistance, chemical resistance, electrical properties, and dimensional stability due to its rigid chain structure. Such a polyimide resin is widely used as an electric / electronic material. However, the polyimide resin has many limitations in its use because it has a dark brown limit due to the formation of a charge transfer complex (CTC) of π electrons present in the imide chain.

A method in which a strong electron attracting group such as a trifluoroalkyl group is introduced in order to solve the above limitation and obtain a colorless transparent polyimide resin, thereby restricting the movement of? Electrons; A method of reducing the formation of CTC by introducing a sulfone (-SO 2 -) group, an ether (-O-) group, or the like into the main chain to form a bent structure; Or introducing an aliphatic cyclic compound to inhibit the formation of resonance structures of? Electrons have been proposed.

However, the polyimide resin according to the above proposals is difficult to exhibit sufficient heat resistance by a bending structure or an aliphatic cyclic compound, and a film produced using the polyimide resin still has a limit to exhibit poor mechanical properties.

On the other hand, in recent years, poly (amide-imide) copolymers having a polyamide unit structure introduced to improve the scratch resistance of polyimide have been developed.

However, the poly (amide-imide) copolymer shows a tendency to easily haze when a film is formed due to its high crystallinity. This haze characteristic of the poly (amide-imide) film is severely expressed as the thickness of the film is thicker and affects the yellow index (YI). In addition, previously known poly (amide-imide) copolymers have a limit of low UV weatherability compared to polyimide.

Accordingly, there is a need to develop a method for securing high UV weatherability while improving the transparency and scratch resistance of a poly (amide-imide) copolymer.

The present invention is to provide a poly (amide-imide) copolymer having mechanical properties such as high scratch resistance and high transparency while having excellent weather resistance.

The present invention also provides a polymer film having mechanical properties such as high scratch resistance and high transparency while having excellent weather resistance.

In the present specification, there is provided a poly (amide-imide) copolymer comprising a repeating unit represented by the following general formula (1) and a repeating unit represented by the following general formula (2), wherein the content of the repeating unit represented by the following general formula (2) is 1 to 40 mol%.

[Chemical Formula 1]

In Formula 1, X is an alicyclic tetravalent functional group having 4 to 10 carbon atoms or an aromatic tetravalent functional group having 6 to 20 carbon atoms.

(2)

In Formula 2, Z is an aromatic trivalent functional group having 6 to 20 carbon atoms.

In the above formulas (1) and (2), Y is represented by the following formula (12).

[Chemical Formula 12]

Wherein L ₁ is a single bond, -O-, -CO-, -S-, -SO ₂ -, -C (CH ₃ ) ₂ -, -C (CF ₃ ) ₂ -, -CONH-, _{-COO-, - (CH 2) n1} -, -O (CH 2) and _{n2 O-, -OCH 2 -C (CH} 3) 2 -CH 2 O- , or -OCO (CH _{2) n3} OCO-, wherein n1, n2 and n3 are each an integer of 1 to 10, and R ₁ and R ₂ may be the same or different and each is a perfluoroalkyl group having 1 to 5 carbon atoms, to be.

Also, in this specification, a polymer film comprising the poly (amide-imide) copolymer is provided.

The poly (amide-imide) copolymer and the polymer film according to a specific embodiment of the present invention will be described in more detail.

According to an embodiment of the present invention, there is provided a poly (amide-imide) copolymer comprising the repeating unit of Formula 1 and the repeating unit of Formula 2, wherein the content of the repeating unit of Formula 2 is 1 to 40 mol% Can be provided.

In accordance with the development trend of flexible or foldable devices, it is required to realize a display that is lightweight, unbreakable, and foldable or tangible. In addition, there is a demand for a colorless transparent film having high hardness and good bendability for realizing such a display. Poly (amide-imide) copolymers obtained by copolymerizing an aromatic amide and an aromatic imide have been proposed as materials for satisfying both high hardness and repeated bending properties. However, since aromatic amides and aromatic imides have inherent color, It has limitations that are not suitable for use. Thus, attempts have been made to remove color using alicyclic compounds in the formation of poly (amide-imide) copolymers. However, in general, the alicyclic unit structure exhibits lower hardness than the aromatic unit structure. Further, in general, the alicyclic diamine compound forms an insoluble precipitate (salt) in the reaction to form an amide bond, which makes the progress of the reaction difficult.

Thus, the present inventors have newly synthesized a poly (amide-imide) copolymer having the above-mentioned structure. In particular, when the content of the repeating unit of the above formula (2), including the repeating unit of the above formula (1) To 40 mol%, the poly (amide-imide) copolymer has excellent mechanical properties such as high scratch resistance and high transparency and has excellent weather resistance.

More specifically, an imide structure and an amide structure are positioned on both sides of the Z in the repeating unit of Formula 2, wherein Z is an aromatic trivalent functional group having 6 to 20 carbon atoms, and Y Is an aromatic functional group of the above formula (12).

As the repeating units of the above formula (2) are contained in the poly (amide-imide) copolymer in an amount of 1 to 40%, preferably 5 to 30 mol%, and more preferably 8 to 25 mol%, high surface hardness and translucency And weather resistance against ultraviolet rays can be realized at the same time.

On the other hand, when the poly (amide-imide) copolymer and the film obtained therefrom do not contain the repeating unit represented by the above-mentioned formula (2), the surface hardness, elasticity and flexibility are low. In addition, the poly (amide-imide) copolymer containing a conventional amide structure having a structure different from that of the repeating unit represented by the above formula (2) has a limit in that the weather resistance against ultraviolet rays is insufficient.

On the other hand, when the content of repeating units in the above formula (2) exceeds 40 mol% in the poly (amide-imide) copolymer, the absorption rate of the poly (amide-imide) Can be degraded.

As described above, the poly (amide-imide) copolymer of the embodiment includes the repeating unit of the above formula (1) and the repeating unit of the above formula (2). The repeating unit of Formula 1 and the repeating unit of Formula 2 may be repeated one or more times, for example, 1 to 10,000 repeating units.

Specific examples of the repeating unit of the formula (1) include repeating units of the following formulas (3) and (4).

(3)

X ₁ in Formula 3 is Formula 31 below.

(31)

In Formula 31, A is single bond, -O-, -CO-, -S-, -SO 2 -, -C (CH 3) 2 -, -C (CF 3) 2 -, -CONH-, - _{COO-, - (CH 2) n1} -, -O (CH 2) n2 O-, or -OCO (CH _{2) n3} a OCO-, wherein n1, n2 and n3 is an integer of 1 to 10, respectively.

[Chemical Formula 4]

X ₂ in the formula (4) is the following formula (41).

(41)

In the above Formulas 31 and 41, * denotes a bonding point.

More specifically, the repeating unit of Formula 1 may include repeating units of Formula 3 and Formula 4.

As the poly (amide-imide) copolymer of the above embodiment contains the repeating unit of the above formula (4), higher transparency and lower yellowness can be ensured. Further, as the poly (amide-imide) copolymer of the embodiment includes the repeating unit of the above formula (3), it can have a high ultraviolet shielding property with improved heat resistance.

In the poly (amide-imide) copolymer of the embodiment, the molar ratio of the repeating unit of the formula (4) to the repeating unit of the formula (3) may be 1.2 to 6. The poly (amide-imide) copolymer or the poly (amide-imide) copolymer prepared from the poly (amide-imide) copolymer may have a higher surface strength or scratch resistance than the repeating unit represented by the formula The transparency of the film can be greatly improved.

In the above formulas (1) and (2), Y is the formula (12), and more specifically, the formula (12) may be the formula (13).

[Chemical Formula 13]

In Formula 11, * denotes a bonding point.

In the above Formulas 1 and 2, since the Y has the structure of Chemical Formula 12 or Chemical Formula 13, the poly (amide-imide) copolymer of the embodiment ensures properties such as high optical transparency and excellent thermal stability can do.

On the other hand, since the physical properties and properties of the poly (amide-imide) copolymer described above include the repeating units of the above formula (1) and the repeating units of the above formula (2), the poly (amide- The total amount of the repeating unit represented by the formula (1) and the repeating unit represented by the formula (2) may be 80 mol% or more, or 90 mol% or more, or 95 mol% or more, or 100 mol%. The poly (amide-imide) copolymer further comprises an imide repeating unit, an amide repeating unit and / or an amide-imide repeating unit conventionally known in addition to the repeating unit of the above formula (1) and the repeating unit of the above formula It is possible.

The poly (amide-imide) copolymer may have a weight average molecular weight of 5,000 to 500,000, or a weight average molecular weight of 30,000 to 300,000. The weight average molecular weight may be a weight average molecular weight in terms of polystyrene measured by a GPC method.

There is no great limitation on the method for synthesizing the poly (amide-imide) copolymer, and a synthesizing apparatus and a method commonly known by using the monomer capable of forming the repeating unit of formula (1) and the repeating unit of formula (2) Can be used.

For example, the monomer capable of forming the repeating unit represented by the formula (1) and the repeating unit represented by the formula (2) may be dissolved in a commonly known organic solvent, and then the polymerization reaction may be carried out at a temperature ranging from -10 ° C to 150 ° C. But is not particularly limited to the above polymerization reaction time.

Examples of the organic solvent that can be used in the polymerization process are not limited. Examples of the organic solvent include N-methylpyrrolidinone (NMP), N, N-dimethylacetamide ), Tetrahydrofuran (THF), N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), cyclohexane, acetonitrile, ethyl Ethyl lactate, and mixtures thereof, may be used.

In the step of synthesizing the poly (amide-imide) copolymer, the repeating unit represented by the formula (1) is preferably an alicyclic tetravalent functional group having 4 to 10 carbon atoms or a tetracarboxylic acid having an aromatic tetravalent functional group having 6 to 20 carbon atoms Can be formed through the reaction of an anhydride with a diamine compound containing a functional group of the formula (12).

Further, in the step of synthesizing the poly (amide-imide) copolymer, the repeating unit of the above-mentioned formula (2) is a compound containing an aromatic trifunctional functional group having 6 to 20 carbon atoms, an acid anhydride functional group and an acyl functional group (or a derivative thereof) Can be formed through the reaction of the diamine compound containing the functional group of the formula (12).

Amic acid functional groups may be formed in the process of forming the repeating unit of formula (1) and the repeating unit of formula (2), and the amic acid may be imidized in a polymerization process or a subsequent process. This imidization can be performed thermally or chemically. For example, the thermal imidization may occur naturally during the formation of the polyamic acid. For the chemical imidization, compounds such as acetic anhydride and pyridine may be used.

The poly (amide-imide) copolymer may be finally obtained through a conventional polymer recovery process such as precipitation, filtration, and drying after the formation of the copolymer.

Meanwhile, according to another embodiment of the present invention, a polymer film comprising the poly (amide-imide) copolymer of one embodiment may be provided.

As described above, the polymer film formed from the poly (amide-imide) copolymer can have excellent weather resistance while having mechanical properties such as high scratch resistance and high transparency. Accordingly, the polymer film formed from the poly (amide-imide) copolymer can be used as a material for various molded articles which require colorless transparency, high scratch resistance and excellent weather resistance. For example, the polymer film can be applied to a display substrate, a protective film for a display, a touch panel, and the like.

Although the thickness of the polymer film is not limited, in order to maintain physical properties such as the above-mentioned physical properties, for example, mechanical properties such as high scratch resistance, high transparency and excellent weather resistance in required fields, , Or a thickness of 1 mu m to 200 mu m.

More specifically, the polymer film may have a pencil hardness of H grade or higher measured according to ASTM D3363 at a thickness of 50 +/- 2 mu m.

In addition, the polymer film may have a light transmittance of 85% or more in a wavelength range of 400 nm to 600 nm.

Further, as described above, the polymer film may have high UV weatherability. More specifically, the polymer film was exposed to ultraviolet rays at a light amount of 1.1 W / m 2 at 50 ° C for 24 hours using QUV Accelerated Weathering Tester (Q-LAB), and then the yellow index of the film was measured according to the measurement method of ASTM D1925 The difference may be less than 3 when the difference (YI) of the yellow index (Y0) value of the unexposed state is measured by measuring the difference (Y1). That is, it can be seen that the polymer film does not change significantly in appearance and optical characteristics even when exposed to ultraviolet light for a long time.

Except for using the above-mentioned poly (amide-imide) copolymer, the polymer film can be used without any limitations in various known methods and apparatuses for producing a polymer film. For example, the polymer film may be obtained by coating a solution containing the poly (amide-imide) copolymer on an arbitrary support to form a film, and drying the film by evaporating the solvent from the film. Stretching and heat treatment may be performed on the polymer film.

The material usable as any support for coating a solution containing the poly (amide-imide) copolymer is not particularly limited. For example, various polymer substrates or plastic substrates, glass substrates, metal substrates such as copper Can be used.

In addition, in the step of applying the solution containing the poly (amide-imide) copolymer on the support, a commonly used application method and apparatus can be used without limitation, and examples thereof include a spray method, Roll coating, spin coating, slit coating, extrusion coating, curtain coating, die coating, wire bar coating, or knife coating may be used.

Further, in the step of producing the polymer film, drying may include a step of drying the solution containing the applied poly (amide-imide) copolymer. The polymeric resin solution applied on the support may be dried at a temperature lower than the boiling point of the solvent used, for example, at 60 to 200 DEG C for 30 seconds to 30 minutes. In the drying step, an arch-type oven or a floating-type oven may be used.

According to the present invention, there can be provided a poly (amide-imide) copolymer and a polymer film containing the same, which have mechanical properties such as high scratch resistance and high weatherability while having high transparency.

The invention will be described in more detail in the following examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[ Example  And Comparative Example : Poly (Amide-imide) copolymer and preparation of polymer film]

Example 1

510 g of dimethylacetamide (DMAC) was slowly poured into a 1 L reactor which was equipped with a stirrer, a nitrogenator, a dropping funnel and a thermostat. While nitrogen was slowly blown, TFDB (2,2'-bis (trifluoromethyl) -diaminobiphenyl) was added and dissolved.

When the TFDB was completely dissolved, 14.5169 g of BPDA (3,3 ', 4,4'-Biphenyltetracarboxylic dianhydride), 19.3523 g of CBDA (Cyclobutane-1,2,3,4-tetracarboxylic dianhydride) and trimellitic acid chloride ) Was added at room temperature to make the concentration of the solid content in the reaction solution 15% by weight.

While the reaction solution was maintained at 25 占 폚, stirring was carried out for 15 hours while slowly blowing nitrogen to obtain a poly (amide-imide) copolymer having a viscosity of 54,000 cps Solution. After 23.4 g of pyridine and 30.2 g of acetic anhydride were added to this poly (amide-imide) copolymer solution, the mixture was stirred at room temperature for 30 minutes, then heated to 70 ° C and stirred for 1 hour. After cooling to room temperature, a solid poly (amide-imide) copolymer was precipitated at 20 L of methanol. [Solid state poly (amide-imide) copolymer: Weight average in terms of polystyrene Molecular weight: about 150,000 g / mol].

The precipitated solid poly (amide-imide) copolymer was pulverized and pulverized, filtered and vacuum-dried in a vacuum oven at 100 ° C for 12 hours. The vacuum dried poly (amide-imide) copolymer powder was dissolved in dimethylacetamide to a solids content of 15% by weight, and then coated on a glass plate to a final thickness of 50 탆.

After the glass plate coating, it was dried at 70 ° C for 5 minutes, dried at 150 ° C for 10 minutes, and then peeled off from the glass plate. The peeled film was fixed to a frame and placed in a high temperature curing oven, followed by curing at 250 DEG C for 30 minutes while flowing nitrogen, thereby obtaining a polymer film having a thickness of about 50 mu m.

Example 2

A poly (amide-imide) copolymer and a polymer film were prepared in the same manner as in Example 1, except that the amounts of BPDA and TMAC used were changed as shown in Table 1 below.

Comparative Example  1 to 3

A poly (amide-imide) copolymer and a polymer film were prepared in the same manner as in Example 1, except that the content of the monomers used was changed as shown in Table 1 below.

Composition ratio (moles basis of TFDB) TFDB CBDA BPDA 6FDA TMAC TPC Example 1 1.0 0.6 0.3 0.1 Example 2 1.0 0.6 0.2 0.2 Comparative Example 1 1.0 0.6 0.2 0.2 Comparative Example 2 1.0 0.8 0.2 Comparative Example 3 1.0 0.2 0.3 0.5

6FDA: 4,4 '- (hexafluoroisopropylidene) diphthalic anhydride

TPC: p-Terephthaloyl chloride

[ Experimental Example : Measurement of Physical Properties of Polymer Film]

(1) Measurement of permeability (T)

The total light transmittance of the polymer films obtained in the Examples and Comparative Examples was measured using a UV-VIS-NIR Spectrophotometer (SolidSpec-3700, SHIMADZU), and the transmittance values for visible light at a wavelength of 550 nm are shown in Table 2 below .

(2) Yellow Index (Y.I.)

(Y.I.) of the polymer films obtained in the above Examples and Comparative Examples were measured according to the measurement method of ASTM D1925 using UV-2600 UV-Vis Spectrometer (SHIMADZU).

(3) Pencil Hardness

The pencil hardness of the polymer films obtained in the above Examples and Comparative Examples was measured according to ASTM D3363 using Pencil Hardness Tester. Specifically, when a pencil having various hardnesses is fixed to the tester and scratches on the film, the degree of occurrence of scratches on the film is visually observed with a microscope or microscope. When the scratches are not scratched by more than 70% of the total number of scratches, The corresponding value was evaluated by the pencil hardness of the film.

(4) UV weatherability measurement

The polymer films obtained in the above Examples and Comparative Examples were exposed to ultraviolet rays at a light amount of 1.1 W / m 2 at 50 캜 for 24 hours using a QUV Accelerated Weathering Tester (Q-LAB) The yellow index (Y1) of the unexposed state was measured to determine the difference (YI) of the yellow index (Y0) value.

The results of the measurement and evaluation are as follows: "⊚" when the change amount (ΔY = Y1-Y0) of the yellowness index is less than 3; "∘" when the variation is less than 3 and less than 5; X '.

(5) Flexibility  Measure

The polymer films obtained in the Examples and Comparative Examples were evaluated for the bending strength of the films by using an MIT type folding endurance tester. Specifically, a specimen (1 cm x 7 cm) of the film was loaded into an impact strength tester and tilted at an angle of 135 ° at a speed of 175 rpm on the left and right sides of the specimen, with a radius of curvature of 0.8 mm and a load of 250 g The number of reciprocating bending cycles was measured

Permeability
(550 nm) Pencil hardness UV weatherability Flexibility
(MIT, times) Example 1 88 H ◎ 24,000 Example 2 89 2H ◎ 21,000 Comparative Example 1 89 2H △ 28,000 Comparative Example 2 90 F ◎ 8,000 Comparative Example 3 88 HB X 33,000

As can be seen in Table 2, the films prepared using the poly (amide-imide) copolymers obtained in Examples 1 and 2 exhibited a high surface hardness of H or higher and a high surface hardness of 20,000 or more Or more and high weather resistance against ultraviolet ray.

On the contrary, in Comparative Examples 1 and 3 including the previously known amide structure (derived from p-Terephthaloyl chloride), the surface hardness and translucency equivalent to those of the Examples can be secured, but the weather resistance against ultraviolet rays is greatly reduced .

In addition, in the case of Comparative Example 2, which does not contain an amide-imide repeating unit derived from trimellitic acid chloride, it was confirmed that not only the surface hardness was significantly lowered but also the bending property of the film remained at a significantly low level.

Claims (9)

A repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2)
Wherein the content of the repeating unit represented by the following formula (2) is 1 to 40 mol%
Poly (amide-imide) copolymer:
[Chemical Formula 1]

In Formula 1, X is an alicyclic tetravalent functional group having 4 to 10 carbon atoms or an aromatic tetravalent functional group having 6 to 20 carbon atoms,
(2)

In Formula 2, Z is an aromatic trivalent functional group having 6 to 20 carbon atoms,
In the general formulas (1) and (2), Y is represented by the following general formula (12)
[Chemical Formula 12]

Wherein L ₁ is a single bond, -O-, -CO-, -S-, -SO ₂ -, -C (CH ₃ ) ₂ -, -C (CF ₃ ) ₂ -, -CONH-, _{-COO-, - (CH 2) n1} -, -O (CH 2) and _{n2 O-, -OCH 2 -C (CH} 3) 2 -CH 2 O- , or -OCO (CH _{2) n3} OCO-, wherein n1, n2 and n3 are each an integer of 1 to 10,
R ₁ and R _{2, which} may be the same or different, each represent a perfluoro alkyl having 1 to 5 carbon atoms, to be.
The method according to claim 1,
Wherein the content of the repeating unit represented by the formula (2) in the poly (amide-imide) copolymer is 5 to 30 mol%
Poly (amide-imide) copolymer.
The method according to claim 1,
The repeating unit represented by the formula (1) includes repeating units represented by the following formulas (3) and (4)
(Amide-imide) copolymer in which the molar ratio of the repeating unit represented by the following formula (4) to the repeating unit represented by the following formula (3) is 1.2 to 6:
(3)

X 3 in the formula ₁ is the following formula 31,
(31)

In Formula 31, A is single bond, -O-, -CO-, -S-, -SO 2 -, -C (CH 3) 2 -, -C (CF 3) 2 -, -CONH-, - _{a, -O (CH 2) n2 O-} , or -OCO (CH _{2) n3} OCO-, and wherein n1, n2 and n3 is an integer from 1 to _{10, - COO-, - (CH 2} ) n1
[Chemical Formula 4]

X ₂ in Formula 4 is represented by the following Formula 41,
(41)

In the above Formulas 31 and 41, * denotes a bonding point.
The method according to claim 1,
Wherein the formula (12) is a poly (amide-imide) copolymer having the following formula (13):
[Chemical Formula 13]

In Formula 11, * denotes a bonding point.
The method according to claim 1,
Wherein the poly (amide-imide) copolymer has a weight average molecular weight of from 5,000 to 500,000.
The method according to claim 1,
(Amide-imide) copolymer comprising at least 80 mol% of the total of the repeating unit represented by the formula (1) and the repeating unit represented by the formula (2).
A polymeric film comprising the poly (amide-imide) copolymer of claim 1.
8. The method of claim 7,
The polymer film has a pencil hardness of H grade or higher measured according to ASTM D3363 at a thickness of 50 +/- 2 mu m,
A polymer film having a transparency of 85% or more in a wavelength region of 400 nm to 600 nm.
8. The method of claim 7,
Wherein said polymer film has a yellow index variation of less than 3 before and after exposure to ultraviolet light for 24 hours at a light amount of 1.1 W / m < 2 > at 50 DEG C using QUV Accelerated Weathering Tester (Q-