Multilayer film, protective film, and multilayer electronic device

Abstract

Embodiments relate to a multilayer film, a protective film, and a multilayer electronic device, and more particularly, to a multilayer film having flexible characteristics over a wide temperature range and excellent and lasting optical characteristics, and the like. The multilayer film includes: a first layer having one surface and another surface; a second layer disposed on one surface of the first layer; and a third layer disposed below the other surface of the first layer, the first layer including a first polymer resin, the first polymer resin including a repeating unit S, the repeating unit S being an ether repeating unit or an ester repeating unit, the difference in haze value of the multilayer film after 168 hours of exposure to air being 1.2% or less.

Description

Technical Field

[0001] Embodiments relate to a multilayer film, a protective film, and a multilayer electronic device having flexible characteristics in a wide temperature range and having excellent optical characteristics. Background Art

[0002] As the form of display devices becomes increasingly diverse, the requirements for their functions are also constantly changing, and are gradually evolving towards larger screens, thinner, and more functional forms. The form of display screens has also evolved from the previous flat form to the curved form, and further developed into foldable, bendable, flexible and other forms. In other words, the recent display form is no longer just developing in the direction of large area, but can achieve form changes such as folding or bending, which is different from the previous development trend of simply expanding the display area.

[0003] As a display screen protective film, PET films with excellent mechanical properties, chemical resistance, moisture resistance and other characteristics are widely used. For example, examples include polyester protective films that can be applied to polarizing plate protective films due to improved optical properties (Korean Patent No. 10-1730854) and protective films that can be applied to touch panels (Korean Patent No. 10-1746170). However, due to its high modulus, PET films may not meet the characteristics required for curved surfaces or curved parts, which may become one of the causes of film warping in multi-layer display devices.

[0004] In addition, compared with hard glass that has been used to protect display modules of display devices installed on portable electronic devices, PET film is weaker in impact mitigation properties (i.e., the function of protecting internal devices such as display modules from external impacts), and therefore has limitations in performing sufficient protection functions.

[0005] On the other hand, the protective film can be used for various purposes depending on its performance.

[0006] Protective films can be used as thin films to protect screens in multi-layer electronic devices with display functions, such as mobile phones, laptops, and monitors. In recent years, with the emergence of flexible devices, protective films for this purpose need to have impact resistance, optical properties, and the ability to withstand repeated folding.

[0007] Protective films can also be applied to paint protection films. Paint protection films are used to protect the paint to prevent the painted surface from being damaged by external impact. For example, automotive paint protection films are called paint protection films (PPF). Paint protection films need to be impact-resistant and have excellent workability, such as being able to stretch well on curved or bent surfaces.

[0008] The above-mentioned background technology is technical information that the inventor possesses in order to derive the embodiments of the present invention or technical information mastered in the process of deriving the present invention, and therefore cannot be considered as public known technology disclosed to the public before the present application. Summary of the invention

[0009] Technical issues

[0010] An object of the embodiment is to provide a multilayer film, a protective film, and a multilayer electronic device having flexibility characteristics in a wide temperature range and excellent optical characteristics.

[0011] Solutions to the problem

[0012] According to one embodiment, a multilayer film includes: a first layer having a surface and another surface; a second layer arranged on one surface of the first layer; and a third layer arranged below the other surface of the first layer, wherein the first layer includes a first polymer resin, and the first polymer resin includes a repeating unit S, and the repeating unit S is an ether repeating unit or an ester repeating unit.

[0013] The multilayer film may have a difference in haze value of 1.2% or less before and after being exposed to air for 168 hours.

[0014] The content of the repeating unit S in the first polymer resin may be 20 wt % or more.

[0015] The multilayer film may have a haze of 3% or less.

[0016] The thickness ratio of the second layer to the first layer in the multilayer film may be 1:0.01 to 1:20.

[0017] The Shore D hardness of the second layer or the third layer in the multi-layer film may be 60 or higher.

[0018] The storage modulus of the multilayer film at about 25° C. may be 1200 MPa or less.

[0019] The storage modulus of the multilayer film at about 0° C. may be 1200 MPa or less.

[0020] The second layer may include a second polymer resin, the third layer may include a third polymer resin, and the second polymer resin and the third polymer resin may contain amide repeating units.

[0021] The third layer may be a bonding layer.

[0022] A protective film according to another embodiment includes a release paper and a multilayer film disposed on the release paper, and the multilayer film is the multilayer film described above.

[0023] A multilayer electronic device according to another embodiment includes the above-mentioned multilayer film.

[0024] Effects of the Invention

[0025] The multilayer film of the embodiment can have flexibility and have more excellent optical characteristics by suppressing haze change. The protective film and multilayer electronic device of the embodiment can provide excellent impact absorption characteristics and durability by applying the multilayer film. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is a conceptual diagram illustrating a structure of a multilayer film according to an embodiment in cross section.

[0027] Figure 2 FIG. 1 is a conceptual diagram illustrating a structure of a multilayer film according to another embodiment in cross section.

[0028] Figure 3 FIG. 1 is a conceptual diagram illustrating a structure of a multilayer film according to still another embodiment in cross section.

[0029] Figure 4 FIG. 1 is a conceptual diagram illustrating a structure of a multilayer electronic device according to an embodiment in cross section. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that a person skilled in the art can easily implement the present invention. However, the present invention can be implemented in a variety of different embodiments and is not limited to the embodiments described in this specification. Throughout the specification, the same or similar components are given the same reference numerals.

[0031] In the present specification, when it is stated that a certain component “includes” another component, unless there is a special statement to the contrary, it means that the other components are also included rather than excluded.

[0032] In this specification, when it is described that one component is “connected” to another component, it includes not only the case of being “directly connected” but also the case of being “connected with other component interposed therebetween”.

[0033] In the present specification, "B is located on A" means that B is located on A in direct contact or with another layer therebetween, and should not be limited to the meaning that B is located on the surface of A in contact.

[0034] In the present specification, the term "combination of..." included in the Markush-type description refers to a mixture or combination of one or more constituent elements selected from the group consisting of the constituent elements of the Markush-type description, thereby meaning that the present invention includes one or more constituent elements selected from the group consisting of the above constituent elements.

[0035] In the present specification, a description in the form of "A and / or B" means "A or B, or A and B".

[0036] In this specification, unless otherwise specified, terms such as "first", "second" or "A", "B", etc. are used to distinguish the same terms from each other.

[0037] Unless otherwise specified, expressions in the singular in the present specification are interpreted as including the singular or plural meaning as explained in the context.

[0038] In this specification, the storage modulus is the storage modulus measured in the temperature range of -50°C to 100°C in a DMAQ800 model of TA instruments according to ASTM D4065. The measurement results are based on the following conditions: Tension Mode of Dynamic Mechanical Analysis (DMA), a frequency of 1 Hz, and a heating rate of 2°C / min.

[0039] In this specification, room temperature refers to about 20°C, and normal temperature refers to about 25°C.

[0040] In the present specification, letters and / or numbers described together with the compound names are abbreviations of the compound names.

[0041] In this specification, the upper part (top) and the lower part (bottom) of each layer are described based on the drawings. However, the layer structure and position of each layer are not limited to the layer structure and position shown in the drawings, and the distinction between upper and lower should be understood as a relative concept to explain the position of each layer.

[0042] In this specification, relative sizes, thicknesses, etc. of components shown in the drawings may be exaggerated for convenience of explanation.

[0043] Figure 1 1 is a conceptual diagram illustrating a structure of a multilayer film according to an embodiment in cross section. Figure 2 FIG. 1 is a conceptual diagram illustrating a structure of a multilayer film according to another embodiment in cross section. Figure 31 is a conceptual diagram illustrating a structure of a multilayer film according to still another embodiment in cross section. Figure 4 FIG. 1 is a conceptual diagram illustrating a structure of a multilayer electronic device according to an embodiment in cross section. Figures 1 to 4 The following embodiments are described in more detail.

[0044] Multilayer film 100

[0045] In order to achieve the above object, the multilayer film 100 according to the embodiment includes: a first layer 10 having one surface and another surface; a second layer 20 arranged on one surface of the first layer; and a third layer 30 arranged below the other surface of the first layer (refer to Figure 1 ).

[0046] The first layer 10 includes a first polymer resin. The first polymer resin includes a repeating unit S. The repeating unit S is an ether repeating unit or an ester repeating unit.

[0047] The multilayer film 100 according to the embodiment has a difference in haze value of 1.2% or less before and after exposure to air for 168 hours.

[0048] The repeating unit S is included in the first layer, which helps to improve the flexibility of the film. In particular, when the repeating unit S is included in the first polymer resin together with the repeating unit H described below, it can help control the degree of flexibility or elasticity. In addition, when a film is prepared by using such a first polymer resin and controlling various properties of the film, a film having excellent flexibility, elasticity and optical properties can be provided.

[0049] However, when the first polymer resin containing the repeating unit S is applied in the form of a film, an increase in haze may be observed over a long period of time. After repeated tests, the inventors of the present invention determined that the above phenomenon is caused by the migration of the oligomer corresponding to the repeating unit S from the inside of the first layer to the surface. In order to suppress this haze change, the inventors of the present invention tried a variety of methods and finally found that if a three-layer multilayer film form as shown in the embodiment is adopted, the surface of the first layer can be effectively prevented from directly contacting the air, while the desired flexibility and elasticity of the first layer can be obtained.

[0050] In other words, when the multilayer film of the embodiment, ie, the three-layer film structure is adopted, the haze does not substantially change even when exposed to air for a long time while maintaining the advantages of the first layer at a predetermined level.

[0051] Specifically, the difference in haze value before and after exposure to air for 168 hours of the multilayer film of the embodiment may be 1.2% or less, 1.0% or less, 0.8% or less, 0.5% or less, 0.3% or less, or 0% or more.

[0052] The first polymer resin may include the repeating unit S in an amount of 20 wt % or more.

[0053] The first polymer resin may include the repeating unit S in an amount of 30 wt % or more.

[0054] The first polymer resin may include the repeating unit S in an amount of 40 wt % or more.

[0055] The first polymer resin may include the repeating unit S in an amount of 50 wt % or more.

[0056] The first polymer resin may include the repeating unit S in an amount of 60 wt % or more.

[0057] The first polymer resin may include the repeating unit S in an amount of 70 wt % or more.

[0058] The first polymer resin may include the repeating unit S in an amount of 100 wt % or less, or may include the repeating unit S in an amount of 90 wt % or less.

[0059] The above-mentioned repeating unit S may include an ether repeating unit and / or an ester repeating unit.

[0060] The sum of the above-mentioned ether repeating units and the above-mentioned ester repeating units in the above-mentioned first polymer resin may include more than 20 weight %, more than 30 weight %, more than 40 weight %, more than 50 weight %, more than 60 weight %, more than 70 weight %, less than 100 weight %, and less than 90 weight %.

[0061] The repeating unit S may include a tetramethylene oxide residue, an ethylene oxide residue and / or a propylene oxide residue.

[0062] The sum of the above-mentioned tetramethylene oxide residues, ethylene oxide residues and propylene oxide residues in the above-mentioned first polymer resin may include more than 20 weight %, more than 30 weight %, more than 40 weight %, more than 50 weight %, more than 60 weight %, more than 70 weight %, less than 100 weight %, and less than 90 weight %.

[0063] Illustratively, the repeating unit S may include -CH2-CH2-CH2-CH2-O-, -CH2-CH2-O- and / or -CH2(-CH2)-CH2-O-.

[0064] The sum of -CH2-CH2-CH2-CH2-O-, -CH2-CH2-O- and -CH2(-CH2)-CH2-O- in the above-mentioned first polymer resin may include more than 20 weight %, more than 30 weight %, more than 40 weight %, more than 50 weight %, more than 70 weight %, less than 100 weight %, and less than 90 weight %.

[0065] The first polymer resin may further include a repeating unit H. The repeating unit H may help to improve the hardness of the film. By acting together with the repeating unit S, the film may be endowed with flexibility and properties of flexibility and elasticity even in a wide temperature range.

[0066] The first polymer resin may include the repeating unit H in an amount of 80 wt % or less.

[0067] The first polymer resin may include the repeating unit H in an amount of 70 wt % or less.

[0068] The first polymer resin may include the repeating unit H in an amount of 60 wt % or less.

[0069] The first polymer resin may include the repeating unit H in an amount of 50 wt % or less.

[0070] The first polymer resin may include the repeating unit H in an amount of 40 wt % or less.

[0071] The first polymer resin may include the repeating unit H in an amount of 30 wt % or less.

[0072] The first polymer resin may include 0 wt % or more of the repeating unit H, or may include 10 wt % or more of the repeating unit H.

[0073] The above-mentioned repeating unit H may include a polyamide residue.

[0074] The first polymer resin may include 80 wt % or less, 70 wt % or less, 60 wt % or less, 50 wt % or less, 40 wt % or less, 30 wt % or less and 0 wt % or more, 10 wt % or more of polyamide residues.

[0075] For example, the above-mentioned polyamide residue may be an aliphatic polyamide residue, a semi-aromatic polyamide residue, a semi-crystalline polyamide residue, an amorphous polyamide residue or a mixture thereof.

[0076] The sum of aliphatic polyamide residues, semi-aromatic polyamide residues, semi-crystalline polyamide residues and amorphous polyamide residues in the above-mentioned first polymer resin may include less than 80 weight %, less than 70 weight %, less than 60 weight %, less than 50 weight %, less than 40 weight %, less than 30 weight %, more than 0 weight %, and more than 10 weight %.

[0077] For example, the aliphatic polyamide residue may be a polycaprolactam (PA 6), a polyundecanamide (PA 11) residue, a poly-lauryllactam (PA 12) residue, a polybutylene adipamide (PA 46) residue, a polyhexamethylene adipamide (PA 66) residue, a polyhexamethyleneazelamide (PA 69) residue, a polyhexamethylenesebacamide (PA 610) residue, a polyhexamethylenedodecanediamide (PA 612) residue, a polydecamethylenedodecanediamide (PA 1012) residue, a polydecamethylenesebacamide (PA 1014) residue, or a polyhexamethylenesebacamide (PA 1016) residue. 1010) residues, polydodecamethylenedodecanediamide (PA 1212) residues, PA11 / NHUA residues as a polyamide copolymer, PA BACM6 residues, PA BACM10 residues, PA BACM12 residues, PA6 / 66 residues or PA 6 / 12 residues.

[0078] The semiaromatic polyamide residue may be a PA6 / 6T residue, a PA66 / 6T residue, a PA 6T / 6I residue, a PA 66 / 6T / 6I residue, a PA 11 / 6T residue, a PA 12 / 6T residue, a PA MXD6 residue or a PAMXD10 residue.

[0079] The semi-crystalline polyamide residue may be a PA 6 residue, a PA 11 residue, a PA 12 residue, a PA 10.10 residue, a PA 10.12 residue, a PA 6.10 residue or a PA 6.12 residue.

[0080] Among the amorphous polyamide residues, the polyamide may be a polyhexamethyleneisophthalamide (PA 6I) residue, a polytrimethylhexamethyleneterephthalamide (PA TMHMDAT) residue, or a PA BACM12 residue; the amide copolymer may be a PA 6 / BMACPI residue, a PA 6 / BAMNT residue, a PA11 / BMACMI residue, a PA11 / BMACMT / BMACMI residue, a PA11 / BACM.I / IPDA.I residue, a PA12 / BMACM.I residue, a PA12 / BACMT / BACMI residue, a PA 12 / BMACMT / BACMI residue, a PA 12 / BACMI / IPDAI residue, a PA 6T / 6I / BACMI residue, or a PA 6T / 6I / BACMT / BACMI residue.

[0081] The first polymer resin used in the first layer 10 may be a polymer resin of Arkema, France. 25R53, 35R53, 40R53, 55R53 or other equivalent products, etc.

[0082] The second layer 20 and the third layer 30 are disposed on one surface and the other surface of the first layer 10, respectively. Thus, the second layer and the third layer prevent the surface of the first layer from being substantially directly in contact with the air. The multilayer film thus disposed substantially suppresses the haze change that may occur when the first layer is exposed to the air. As for the resin, as of 2022, the content of the repeating unit corresponding to the repeating unit S in the commercially available products is in the range of about 5 wt % to 81 wt %. The inventors of the present invention have confirmed through experiments that when a single-layer film is prepared using the above-mentioned resin, the higher the content of the repeating unit S, the more drastic the haze change. Specifically, when the content of the repeating unit S reaches 20 wt % or more, the haze change of the film is more obvious. The embodiment can provide a film having excellent optical properties while being able to substantially suppress the haze change while applying the above-mentioned resin.

[0083] As the second layer 20 of the embodiment, a layer having high hardness may be arranged. By adopting a layer having a relatively high hardness as the second layer, it is also possible to obtain an effect of preventing the surface of the first layer having a relatively low hardness from being damaged.

[0084] The second layer 20 may include a second polymer resin.

[0085] For example, the second layer 20 may be an elastomer layer. The second polymer resin may be an elastic resin.

[0086] Exemplarily, the second layer 20 may be a polymer resin layer including an amide residue. The second polymer resin may be a polymer resin including an amide residue.

[0087] For example, the second layer 20 may be an elastic polyamide layer. The second polymer resin may be an elastic polyamide resin.

[0088] Exemplarily, the second layer 20 may be a polyether block amide layer. The second polymer resin may be a polyether block amide resin. When the second polymer resin is a polyether block amide resin, the content of tetramethylene oxide residues, ethylene oxide residues and / or propylene oxide residues contained in the resin may be less than 20 wt % based on the total amount of the resin. In this case, the degree of change of haze over time may be better suppressed.

[0089] Exemplarily, the second layer 20 may be a thermoplastic polyurethane layer. The second polymer resin may be a thermoplastic polyurethane resin.

[0090] For example, the second layer 20 may be a polyetherester copolymer layer. The second polymer resin may be a polyetherester copolymer resin.

[0091] Illustratively, the second layer 20 may be a thin film layer.

[0092] Illustratively, the second layer 20 may be a coating.

[0093] When a layer having an amide residue is used as the second layer 20 , the bonding strength with the first layer can be relatively excellent.

[0094] The second polymer resin used in the second layer 20 may be a polymer resin of Arkema, France. 72R53, Clear1200, BESNO or other equivalent products, etc.

[0095] As the second layer 20, a layer having a harder hardness than the first layer 10 may be used. Specifically, the surface hardness of the second layer 20 may be greater than 60, or greater than 68. The surface hardness may be less than 80. The surface hardness is based on the Shore D hardness measured on the surface of the second layer according to the ASTM D2240 standard.

[0096] In an embodiment, the thickness ratio of the first layer 10 to the second layer 20 may be 1:0.01 to 1:20. The above thickness ratio may be 1:0.01 to 1:5, or may be 1:0.01 to 1:2, or may be 1:0.03 to 1:1.2. The above thickness ratio may be 1:0.04 to 1:0.5, or may be 1:0.05 to 1:0.3. When the first layer and the second layer are applied according to the above thickness ratio, an excellent multilayer film having excellent surface hardness and elasticity at the same time and substantially no haze change even when exposed to air for a long time can be provided.

[0097] In an embodiment, the first layer 10 may be a softer layer than the second layer 20 .

[0098] The storage modulus of the first layer 10 may be smaller than the storage modulus of the second layer 20 .

[0099] At room temperature, the storage modulus of the first layer 10 may be smaller than the storage modulus of the second layer 20. At 0°C, the storage modulus of the first layer 10 may be smaller than the storage modulus of the second layer 20. At -20°C, the storage modulus of the first layer 10 may be smaller than the storage modulus of the second layer 20. At -40°C, the storage modulus of the first layer 10 may be smaller than the storage modulus of the second layer 20. In this case, the multilayer film can more stably maintain the flexible property.

[0100] As the third layer 30 of the embodiment, a layer having high hardness may be arranged. By adopting a layer having high hardness as the third layer, an effect of preventing the surface of the first layer having relatively low hardness from being damaged can also be obtained.

[0101] The third layer 30 may include a third polymer resin.

[0102] For example, the third layer 30 may be an elastomer layer. The third polymer resin may be an elastic resin.

[0103] For example, the third layer 30 may be a polymer resin layer including an amide residue. The third polymer resin may be a polymer resin including an amide residue.

[0104] For example, the third layer 30 may be an elastic polyamide layer. The third polymer resin may be an elastic polyamide resin.

[0105] Exemplarily, the third layer 30 may be a polyether block amide layer. The third polymer resin may be a polyether block amide resin. When the third polymer resin is a polyether block amide resin, the content of tetramethylene oxide residues, ethylene oxide residues and / or propylene oxide residues contained in the resin may be less than 20% by weight based on the total amount of the resin. In this case, the degree of change of haze over time may be better suppressed.

[0106] For example, the third layer 30 may be a thermoplastic polyurethane layer. The third polymer resin may be a thermoplastic polyurethane resin.

[0107] For example, the third layer 30 may be a polyetherester copolymer layer. The third polymer resin may be a polyetherester copolymer resin.

[0108] Exemplarily, the third layer 30 may be a thin film layer.

[0109] Exemplarily, the third layer 30 may be a coating.

[0110] When a layer having an amide residue is used as the third layer 30 , the bonding strength with the first layer can be relatively excellent.

[0111] The third polymer resin used in the third layer 30 may be a polymer resin of Arkema, France. 72R53, Clear1200, BESNO or other equivalent products, etc.

[0112] As the third layer 30, a layer having a harder hardness than the first layer 10 may be used. Specifically, the surface hardness of the third layer 30 may be greater than 60, or greater than 68. The surface hardness may be less than 80. The surface hardness is based on the Shore D hardness measured on the surface of the third layer according to the ASTM D2240 standard.

[0113] In an embodiment, the third layer 30 may be a bonding layer (see Figure 3 ). In this case, the multilayer film having the elasticity of the first layer and the surface protection properties of the second layer can be conveniently bonded to other substrates.

[0114] The adhesive layer may be exposed to the outside or opposite to a surface of a release film (not shown in the figure). For example, a PET film may be used as the release film, but is not limited thereto.

[0115] In an embodiment, the second layer 20 and the third layer 30 may be adhesive layers (not shown in the figure). In this case, the first layer may be conveniently bonded to other substrates through the second layer and the third layer.

[0116] The adhesive layer may be exposed to the outside or opposite to a surface of a release film (not shown in the figure). For example, a PET film may be used as the release film, but is not limited thereto.

[0117] The adhesive layer may be an acrylic adhesive layer, a polyurethane adhesive layer or a silicone adhesive layer. Specifically, a silicone adhesive layer may be used.

[0118] The silicone-based adhesive layer can be obtained by applying the silicone adhesive composition and then drying and / or curing it.

[0119] The organosilicon bonding composition may include an organosilicon bonding agent, a catalyst and a solvent.

[0120] In an embodiment, an organosilicon MQ resin may be further included to improve the bonding force of the organosilicon-based adhesive layer. Wherein, the organosilicon MQ resin is a polymer having at least two methyl groups in the siloxane skeleton in the cage-like oligosiloxanes represented by the general formula RnSiXmOy. In the general formula, R can be an alkyl group having 1 to 5 carbon atoms, including at least two methyl groups. In the general formula, X is hydrogen, hydroxyl, chloro or an alkoxy group having 1 to 5 carbon atoms. In the general formula, n, m and y are integers of 2 to 200, respectively. Specifically, it can include R1R2X3SiO 1 / 2 The M units (mono-terminated siloxane units) represented by SiO 4 / 2 The weight average molecular weight may be 2000 g / mol to 8000 g / mol. When the organosilicon MQ resin is applied to the bonding layer, the bonding force, especially the initial bonding force, can be improved.

[0121] As the silicone adhesive, a commercially available silicone adhesive that can be used for optical purposes can be used. Specifically, a peroxide curing silicone adhesive can be used, and an addition reaction type silicone adhesive can also be used.

[0122] For example, the peroxide-curable silicone adhesive may be KR-100, KR-101-10, KR-130 manufactured by Shin-Etsu Chemical, DOWSIL SH 4280 manufactured by The Dow Chemical Company, SilGrip PSA 510 manufactured by Momentip Performance Materials, or equivalent products thereof.

[0123] For example, the addition reaction type silicone adhesive can use KR-3700, KR-3701, X-40-3237, X-40-3240 and X-40-3291-1 of Shin-Etsu Chemical Company; DOWSIL SD4580, DOWSIL 4584, DOWSIL 4585 and DOWSIL 4587L of Dow Chemical Company; SilGrip TSR1512, TSR1516 of Momentive Performance Materials; etc. or equivalent products.

[0124] As the silicone binder, use of an addition reaction type silicone binder may be advantageous in terms of process convenience.

[0125] For the purpose of enhancing the bonding strength, the silicone MQ resin can be used together with the silicone adhesive. For example, the silicone MQ resin can be applied to X-92-128 and X-41-3003 of Shin-Etsu Chemical Co., Ltd.; SilGrip SR545, SilGrip SR1000 of Momentive Advanced Materials Co., Ltd.; or the like or equivalent products.

[0126] As a catalyst, a platinum catalyst can be applied, and illustratively, CAT-PL-50T of Shin-Etsu Chemical Co., Ltd. or its equivalent can be used. The above catalyst shortens the curing time, so that even if a relatively heat-sensitive transparent film or substrate is applied, a bonding layer can be effectively formed without substantially damaging the substrate. The bonding layer can be formed to a thickness of 1 μm to 20 μm, preferably, to a thickness of 4 μm to 15 μm. In this case, it can be thinner and have good bonding force.

[0127] In an embodiment, the thickness ratio of the first layer 10 to the third layer 30 may be 1:0.01 to 1:20. The above thickness ratio may be 1:0.01 to 1:5, or may be 1:0.01 to 1:2, or may be 1:0.03 to 1:1.2. The above thickness ratio may be 1:0.04 to 1:0.5, or may be 1:0.05 to 1:0.3. When the first layer and the third layer are applied at such a thickness ratio, an excellent multilayer film may be provided, that is, the multilayer film has both excellent surface hardness and excellent elasticity, and the haze is substantially unchanged even when exposed to the air for a relatively long time.

[0128] In an embodiment, the first layer 10 may be a more flexible layer than the third layer 30 .

[0129] The storage modulus of the first layer 10 may be smaller than the storage modulus of the third layer 30 .

[0130] At room temperature, the storage modulus of the first layer 10 may be smaller than the storage modulus of the third layer 30. At 0°C, the storage modulus of the first layer 10 may be smaller than the storage modulus of the third layer 30. At -20°C, the storage modulus of the first layer 10 may be smaller than the storage modulus of the third layer 30. At -40°C, the storage modulus of the first layer 10 may be smaller than the storage modulus of the third layer 30. In this case, the multilayer film can more stably maintain the flexible property.

[0131] The multilayer film 100 of the embodiment may further include a hard coating layer 40 disposed on the second layer 20 (see Figure 3 ). As the above-mentioned hard coating layer, any hard coating layer generally used for optical films can be applied.

[0132] The multilayer film 100 may have a storage modulus of less than or equal to 1200 MPa at about 25° C. The storage modulus may be 800 MPa or less, 500 MPa or less, or 350 MPa or less. The storage modulus of the multilayer film 100 at 25° C. may be 60 MPa or more, or may be 90 MPa or more.

[0133] The multilayer film 100 may have a storage modulus of less than or equal to 1200 MPa at about 0° C. The storage modulus may be 800 MPa or less, 500 MPa or less, or 400 MPa or less. The storage modulus of the multilayer film 100 at 0° C. may be 100 MPa or more, or may be 110 MPa or more.

[0134] The storage modulus of this multilayer film is relatively higher than that of the single layer film of the first layer, and relatively lower than that of the single layer film of the second layer, so it has appropriate flexibility and is suitable as a protective film for flexible displays. In addition, the multilayer film with this storage modulus characteristic has good flexibility and can be well stretched to adapt to curved or folded surfaces, so it also has advantages when used as a PPF protective film.

[0135] The haze of the multilayer film 100 may be 3% or less, or 2% or less, or 1% or less. The haze may be 0% or more, or 0.1% or more. This indicates that the multilayer film has excellent optical properties.

[0136] The haze of the first layer 10 may be 3% or less, or 2% or less, or 1% or less. The haze may be 0% or more, or 0.1% or more.

[0137] The visible light transmittance of the multilayer film 100 may be 88% or more, or 90% or more. The transmittance may be 99% or less, or 95% or less. This indicates that the multilayer film has excellent optical properties. The transmittance is based on the total light transmittance according to ISO 13468.

[0138] The visible light transmittance of the first layer 10 may be 88% or more, or 90% or more. The transmittance may be 99% or less, or 95% or less. The transmittance is based on the total light transmittance according to ISO 13468.

[0139] The transmission yellowness index of the multilayer film 100 may be 1 or less, or 0.8 or less, or 0.65 or less, or 0.6 or less. The above transmission yellowness index may be 0 or more, or 0.3 or more. This indicates that the multilayer film has excellent optical properties.

[0140] The first layer 10 may have a transmission yellowness index of 1 or less, or 0.8 or less, or 0.65 or less, or 0.6 or less. The transmission yellowness index may be 0 or more, or 0.3 or more.

[0141] The multilayer film 100 has a property that the difference in haze value before and after exposure to air for 168 hours is extremely small. Specifically, the above haze value difference can be less than 1.2%, less than 1.0%, less than 0.8%, less than 0.5%, less than 0.3% and more than 0%. The above haze value difference can be more than 0%. The above haze value difference is different from the difference that occurs when the first layer 10 is exposed to air alone, which shows that the multilayer film 100 in the embodiment can maintain excellent optical properties for a long time by arranging the second layer and the third layer on one surface and the other surface of the first layer 10, respectively.

[0142] The polymer including amide residues may include elastic polyamide (long chain polyamide). For example, elastic polyamide may be Arkema's wait.

[0143] The polymer including amide residues may include polyether block amide (PEBA). For example, the polyether block amide may be PEBA from Arkema France. EVONIK E, etc.

[0144] For example, the elastic resin may include thermoplastic polyurethane (TPU), that is, a copolymer of polyurethane blocks (PU) and polyether blocks (PE), which is also called polyether polyurethane.

[0145] The elastic resin may include copolyetherester (COPE).

[0146] When the first layer 10 and the second layer 20 each independently include a polymer resin containing an amide residue, the first layer and the second layer may be prepared by coextrusion. In this case, even if a separate adhesive layer is not formed between the first layer and the second layer, sufficient adhesive force may be provided so that delamination does not occur.

[0147] When the first layer 10, the second layer 20 and the third layer 30 each independently include a polymer resin containing an amide residue, the first layer, the second layer and the third layer can be prepared by coextrusion. In this case, even if a separate adhesive layer is not formed between the first layer and the second layer, and between the first layer and the third layer, sufficient adhesive force can be provided so that peeling (delamination) does not occur.

[0148] When the first layer 10 and the second layer 20 independently include polymer resins containing amide residues, the amide residue content per unit resin volume in the second layer can be greater than the amide residue content per unit resin volume in the first layer. Specifically, the weight ratio of the amide residue content of the first layer to the amide residue content per unit resin volume in the second layer can be 1:1.3 to 1:8, or can be 1:1.3 to 1:7, or can be 1:1.5 to 1:5.5. At this time, the ratio of amide residues is based on the amide residues contained in each resin (resin of the same volume). When the above content is used to form the first and second layers, not only can the optical properties of the first layer be prevented from deteriorating, but also the surface damage of the multilayer film caused by scratches, etc. can be reduced. In addition, it can also have the characteristics of excellent interface bonding force between the first layer and the second layer.

[0149] When the first layer 10 and the third layer 30 each independently include a polymer resin containing an amide residue, the amide residue content per unit resin volume in the third layer may be greater than the amide residue content per unit resin volume in the first layer. Specifically, the weight ratio of the amide residue content per unit resin volume in the first layer to the amide residue content per unit resin volume in the third layer may be 1:1.3 to 1:8, or may be 1:1.3 to 1:7, or may be 1:1.5 to 1:5.5. When the above-mentioned first layer and the above-mentioned third layer are constituted using the above-mentioned contents, not only can the optical properties of the first layer be prevented from being degraded, but also the surface damage of the multilayer film caused by scratches, etc. can be reduced. In addition, the interface bonding force between the first layer and the third layer may be excellent.

[0150] The method for preparing the multilayer film can adopt a method for preparing a co-extrusion film. For example, the first layer composition, the second layer composition and the third layer composition are put into a co-extruder, and the multilayer film is prepared by co-extrusion. The first layer composition, the second layer composition and the third layer composition can respectively use the first polymer resin, the second polymer resin and the third polymer resin. In this case, the process can be simplified, and the first layer and the second layer can have a better bonding force.

[0151] The method for preparing the multilayer film can be to form a coating layer after preparing a coextruded film. The coextruded film can be prepared by putting the first layer composition and the second layer composition into a coextruder for coextrusion to prepare a two-layer film, and then forming a coating layer on the other surface of the first layer and curing it to prepare the multilayer film.

[0152] The multilayer film can also be prepared in the following manner, that is, firstly, the first layer composition is put into an extruder to prepare a first layer film, and then the second layer and the third layer are formed or attached on one surface and the other surface of the first layer respectively.

[0153] In the above-mentioned extrusion or coextrusion process, the haze, light transmittance and other properties of the film can be adjusted by controlling the surface roughness of the carrier film, etc. Exemplarily, as the surface roughness of the above-mentioned carrier film, the surface roughness Ra can be 0.01μm to 0.5μm. When a carrier film and / or roller with the above-mentioned surface roughness is used, a film with better optical properties can be obtained. The above-mentioned carrier film can be applied to polyethylene terephthalate (PET) film or polyethylene (PE) film, but is not limited thereto.

[0154] Protective film 77 and multilayer electronic device 700

[0155] The protective film 77 according to the embodiment includes a release paper (not shown in the figure) and a multilayer film arranged on the release paper. As the release paper, a polyethylene terephthalate (PET) film or a polyethylene (PE) film can be applied, but is not limited thereto. The protective film 77 can apply the multilayer film 100, and the specific description of the multilayer film is applicable to the protective film.

[0156] The multilayer electronic device 700 according to the embodiment includes a protective film 77, a functional layer 75 disposed under the protective film 77, a light emitting layer 73 disposed under the functional layer 75, and a support layer 71 disposed under the light emitting layer 73 (see FIG. 1 ). Figure 4 ).

[0157] The protection film 77 may serve as a cover layer of the multilayer electronic device 700 .

[0158] The multilayer electronic device 700 may be, for example, a display device, and may be, for example, a large-area display device, a foldable display device, a bendable display device, or a flexible display device. Furthermore, the multilayer electronic device 700 may be a bendable mobile communication device (e.g., a mobile phone) or a bendable laptop computer.

[0159] The light-emitting layer 73 includes an element that emits light according to a signal in the display device. Exemplarily, the light-emitting layer may include a signal transmission layer that transmits an external electrical signal to a color development layer, a color development layer that is arranged on the signal transmission layer and develops color according to a given signal, and an encapsulation layer that protects the color development layer. The signal transmission layer may include a thin film transistor (TFT), for example, LTPS, a-SiTFT or oxide TFT (Oxide TFT) may be applied, but is not limited thereto. As an encapsulation layer, a thin film encapsulation (TFE) may be applied, but is not limited thereto.

[0160] The light emitting layer may be disposed on the support layer 71. As the support layer, a layer having insulation and heat resistance may be applied, and illustratively, a polyimide film, a glass layer, a PET film, etc. may be applied.

[0161] The functional layer 75 may include a sensor layer (not shown in the figure). As the sensor layer, a touch sensor or the like may be applied.

[0162] The functional layer 75 may further include a polarizing layer (not shown in the figure). The polarizing layer may be arranged on the light emitting layer or on the sensor layer.

[0163] As the protective film 77 , the multilayer film 100 can be used.

[0164] The protective film 77 may include the multi-layer film 100 .

[0165] In this case, a cover layer having flexibility, impact resistance and surface strength can be provided to a multilayer electronic device. The protective film is particularly advantageous for application to a multilayer electronic device having a bending or winding function, and has excellent surface strength, so it is durable even when applied as a layer exposed to the outside, and has excellent modulus characteristics, thereby being able to improve the function of protecting the internal device from external impact.

[0166] Protective film

[0167] The protective film (coating protective film, not shown in the figure) may include the multi-layer film 100 described above.

[0168] The protective film can be arranged on the exterior surfaces of electronic devices, automobiles, furniture, etc. to protect the surface and coating.

[0169] The protective film may be directly applied to the multi-layer film 100 described above, or may be applied to a structure further including an adhesive layer below the first layer or the third layer.

[0170] The multilayer film has excellent optical properties, outstanding impact resistance and surface hardness, making it ideal for protecting surfaces, and can be easily bonded even to curved or folded surfaces due to its excellent flexibility.

[0171] The following will be described in more detail by way of specific examples. The following examples are only examples for helping to understand the present invention, and the scope of the present invention is not limited thereto.

[0172] 1. Resin Preparation

[0173] As the first layer resin composition and the second layer resin composition, materials shown in the following Table 1 were used respectively. 72R53 (containing about 95 wt. % PA11 residues as amide residues and about 5 wt. % polytetramethylene glycol residues), 40R53 (containing about 46 wt. % PA11 residues as amide residues and about 54 wt. % polytetramethylene glycol residues) and 35R53 (containing about 31% by weight of PA11 residues as amide residues and about 69% by weight of polytetramethylene glycol residues) are all commercially available polyether block amide resins, and are abbreviated as 72R53, 40R53 and 35R53, respectively. Clear1200 is a polyamide Clear Micro-crystalline 1200 resin, referred to as 1200. The above resins are all purchased from Arkema, France.

[0174] 2. Preparation of sample films I

[0175] The multilayer film was prepared by a co-extruder owned by SKC. The film was prepared using a skin-core-skin structure of the second layer-first layer-third layer, and the thicknesses of about 5 μm-about 40 μm-about 5 μm were applied respectively, thereby preparing a multilayer film with a total thickness of about 50 μm. The single-layer film of the comparative example was prepared by extrusion to have a thickness of about 50 μm. The film was stored in a state where PET protective films were arranged on both sides.

[0176] 3. Evaluation of Physical Properties of Multilayer Films I

[0177] Measurement of Optical Properties and Color The average visible light transmittance of the film sample was measured according to ISO 13468, and the haze was measured according to ISO 14782 using a haze meter (NDH-5000W, Nippon Denshoku Industries Co., Ltd.).

[0178] The thickness of each layer was measured using an F-20 device from Filmetrics according to the manufacturer's manual. The measurement results were confirmed at 3 to 5 points in the sample and the average value was used as the thickness.

[0179] The difference in haze value (delta haze (deltaH)) before and after exposure to air for 168 hours after removal of the double-sided protective film was measured according to the haze measurement method described above and calculated using the following formula.

[0180] δHaze = Haze measured after the sample film is exposed to air for 168 hours after removing the double-sided protective film - Haze measured immediately after removing the double-sided protective film

[0181] The above average results are shown in Table 1 below.

[0182] Table 1

[0183]

[0184] *Haze of sample film measured immediately after removing the protective film.

[0185] Referring to Table 1 above, it can be confirmed that the haze value of the film of the comparative example has changed, while the haze value of the film of the example has not substantially changed.

[0186] 4. Preparation of sample films Ⅱ and evaluation of physical properties Ⅱ

[0187] In the same manner as in the above 2. Preparation of sample film I, a multilayer film having a three-layer structure was prepared using the resins described in the following Table 2. Similarly, a single-layer film having a thickness of about 50 μm was also prepared.

[0188] According to ASTM D4065, the storage modulus (Storage Modulus, E') of each sample film was evaluated using TA Instruments' DMA Q800 model equipment. The above device measures the storage modulus (E') in the temperature range of -40°C to +80°C in MPa at a frequency of 1 Hz and a heating rate of 2°C / min under DMA (Dynamic Mechanical Analysis) tension mode. The measurement results are shown in Table 2 at 0°C and 25°C. The amplitude (Amplitude) is 5μm and the preforce (Preforce) is 0.01N.

[0189] Table 2

[0190]

[0191] *Indicates the stacking structure of the second layer / first layer / third layer.

[0192] * The experimental results confirmed that the data-Haze value of all samples in the examples was 0.5% as shown in Table 1 above.

[0193] Referring to Table 2 above, the haze of Examples 2-1 to 2-5 above has almost no change, and has a storage modulus range suitable for application as a protective film, so that a film can be provided that not only has optical properties that suppress haze changes over time, but also has a storage modulus with excellent flexibility and impact protection effect.

[0194] The preferred embodiments of the present invention are described in detail above, but the scope of the present invention is not limited thereto. Various modifications and improvements by ordinary technicians in the technical field of the present invention using the basic concepts of the present invention defined in the scope of protection of the attached invention claims also fall within the scope of the present invention.

[0195] Description of Reference Numerals

[0196] 100: Multilayer film

[0197] 10: First floor

[0198] 20: Second floor

[0199] 22: The surface of the second layer

[0200] 30: Third floor

[0201] 40: Hard coating

[0202] 50: Adhesive layer

[0203] 700: Multilayer electronic device

[0204] 71: Support layer

[0205] 73: Luminous layer

[0206] 75: Functional layer

[0207] 77: Protective film

Claims

1. A multilayer film, characterized in that: include: a first layer having a first surface and another surface; A second layer is arranged on a surface of the first layer; and The third layer is arranged below the other surface of the first layer. The first layer comprises a first polymer resin, The first polymer resin comprises a repeating unit S, The above repeating unit S is an ether repeating unit or an ester repeating unit, The difference in haze value between the multilayer film before and after exposure to air for 168 hours was 1.2% or less.

2. The multilayer film according to claim 1, characterized in that The content of the repeating unit S in the first polymer resin is 20% by weight or more.

3. The multilayer film according to claim 1, characterized in that The haze is 3% or less.

4. The multilayer film according to claim 1, characterized in that The thickness ratio of the first layer to the second layer is 1:0.01 to 1:

20.

5. The multilayer film according to claim 1, characterized in that The second layer or the third layer has a Shore D hardness of 60 or more.

6. The multilayer film according to claim 1, characterized in that The multilayer film has a storage modulus of 1200 MPa or less at about 25° C. and a storage modulus of 1200 MPa or less at about 0° C.

7. The multilayer film according to claim 1, characterized in that The second layer comprises a second polymer resin, The third layer includes a third polymer resin, The second polymer resin and the third polymer resin contain amide repeating units.

8. The multilayer film according to claim 1, characterized in that The third layer is a bonding layer.

9. A protective film, characterized in that: The invention comprises a release paper and a multi-layer film arranged on the release paper, wherein the multi-layer film is the multi-layer film according to claim 1.

10. A multilayer electronic device, characterized in that: Comprising the multilayer film according to claim 1.

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