Film

Abstract

An embodiment of the present invention relates to a film comprising a polyether block amide copolymer resin and a polyvinyl acetal resin, the film having a yellowness change value (dYI) represented by formula 1 after exposure to light for an exposure time of 120 hours, the light having a wavelength of 310 nm and an output of 0.68 W / m2, and the yellowness change value of 2 or less. [Formula 1] dYI = YI2-YI1. In formula 1, YI1 is the yellowness value of the thin film before being exposed to the light, and YI2 is the yellowness value of the thin film after being exposed to the light for the exposure time. The film according to an embodiment can maintain excellent optical properties and mechanical properties even when exposed to ultraviolet light for a long period of time.

Description

Technical Field

[0001] The embodiments relate to a thin film with excellent mechanical strength and optical properties.

[0002] [Cross-references to related applications] This document claims priority to Korean Patent Application No. 10-2023-0129042, filed on September 26, 2023, and Korean Patent Application No. 10-2023-0129043, filed on September 26, 2023, the entire contents of which are incorporated herein by reference. Background Technology

[0003] To protect painted surfaces such as those on automobiles, film laminates containing materials like polyurethane (TPU) and polyvinyl chloride (PVC) have traditionally been applied. However, when these polyurethane and PVC film laminates are applied to painted surfaces, their elastic properties change significantly due to external environmental factors, particularly temperature variations, hindering the application process. While internal air conditioning and localized heating systems can be used to manage the temperature of the work area during winter, these methods still offer shortcomings in terms of ease of use, completion rate, and quality.

[0004] Furthermore, polyurethane, polyvinyl chloride, and other materials mentioned above suffer from yellowing due to the characteristics of the raw materials. This raises concerns that the color of the painted surface may continue to change to a degree that is visible to the naked eye after application. To mitigate this issue, attempts have been made to enhance lightfastness in the outermost coating and adhesive layers of the raw material films and film laminates; however, this yellowing phenomenon remains a problem after painting.

[0005] The background technology described above is technical information held by the inventor for the purpose of deriving embodiments or acquired during the deriving process, and is not necessarily publicly known technology disclosed to the general public before this invention application.

[0006] As relevant prior art, there are "water-based coating composition for automotive interior materials" disclosed in Korean Patent Publication No. 10-2011-0082893 and "urethane film for paint protection film and paint protection film including the same" disclosed in Korean Patent Publication No. 10-2021-0013842. Summary of the Invention

[0007] Technical issues The purpose of this embodiment is to provide a film that can maintain excellent resistance to yellowing and mechanical properties even when exposed to ultraviolet light for a long time.

[0008] Solution to the problem To achieve the above objectives, the film according to at least one embodiment comprises: i) a polyether block amide copolymer resin; and ii) a polyvinyl acetal resin or a polyvinyl alcohol resin.

[0009] The change in yellowness (dYI) of the thin film after exposure to light for a given time is expressed by Equation 1 below, where the light has a wavelength of 310 nm and an output of 0.68 W / m. 2 The light exposure time was 120 hours, and the yellowness change value was less than 2.

[0010] [Formula 1] dYI = YI_2 - YI_1 In Equation 1 above, YI_1 is the yellowness value of the film before it is exposed to the light, and YI_2 is the yellowness value of the film after it is exposed to the light for the exposure time.

[0011] In Equation 1 above, YI_1 is the yellowness value of the film before it is exposed to the light, and YI_2 is the yellowness value of the film after it is exposed to the light for the exposure time.

[0012] The light mentioned above has a wavelength of 340nm and an output of 0.72W / m. 2 When exposed to light for 1200 hours, the yellowness change of the film can be less than 0.3.

[0013] The aforementioned polyvinyl acetal resin or polyvinyl alcohol resin may contain hydroxyl groups in its side chain.

[0014] The aforementioned film is based on 100 parts by weight of the sum of the above i) polyether block amide copolymer resin and ii) polyvinyl acetal resin or polyvinyl alcohol resin, and may include up to 20 parts by weight of plasticizer.

[0015] The difference in haze value of the above-mentioned film before and after being placed in a 60°C oven for 7 days can be less than 1%.

[0016] To achieve the above objectives, the film according to at least one embodiment comprises: i) a polyether block amide copolymer resin; and ii) a polyvinyl acetal resin or a polyvinyl alcohol resin, wherein the change in yellowness (dYI) of the film after exposure to light for a given time is expressed by Formula 1 below, wherein the light has a wavelength of 340 nm and an output of 0.72 W / m. 2 The light exposure time was 1200 hours, and the yellowness change value was less than 0.3.

[0017] [Formula 1] dYI = YI_2 - YI_1 In Equation 1 above, YI_1 above represents the yellowness value of the thin film before it was exposed to the aforementioned light. YI_2 is the yellowness value of the film after being exposed to the light for the aforementioned exposure time.

[0018] Based on the total of 100 parts by weight of the above-mentioned polyether block amide copolymer resin and polyvinyl acetal resin, it may further include less than 5 parts by weight of light absorber.

[0019] The above-mentioned film at 0.68W / m 2 Even after being irradiated with UVB light with a wavelength of 310nm for 288 hours, no breakage occurs.

[0020] To achieve the above objectives, the surface protective film according to at least one embodiment includes the film described above. The surface protective film is disposed on a substrate, which may be a substrate with a coating formed thereon.

[0021] The effects of the invention The thin film of the embodiments maintains excellent optical and mechanical properties even when exposed to ultraviolet light for extended periods. However, the effects of the embodiments are not limited to those mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description. Detailed Implementation

[0022] The following detailed description is provided to enable those skilled in the art to readily implement the embodiments. However, the embodiments can be implemented in many different forms and are not limited to the examples described herein.

[0023] In the specification, when it is mentioned that a certain composition "includes" another composition, unless otherwise stated, this does not mean that other compositions are excluded, but rather that other compositions may be further included.

[0024] In this specification, when it is mentioned that one component is "connected" to another component, this includes not only the case of "direct connection" but also the case of "connection with other components in between".

[0025] In this specification, "B is located on A" means that B is located on A in direct contact with A or in the presence of other components therebetween, and should not be limited to the interpretation that B is in contact with the surface of A.

[0026] In this specification, the term "combination thereof" in the Markush form of expression refers to at least one mixture or combination of the group of constituent elements described in the Markush form of expression, meaning that it includes at least one of the group of constituent elements described above.

[0027] In this specification, the reference to "A and / or B" means "A, B, or A and B".

[0028] In this specification, the terms “first,” “second,” or “A,” “B,” etc., are used to distinguish the same terms from one another unless otherwise specified.

[0029] In this specification, the singular expression is interpreted, unless otherwise specified, to include the meaning of singular or plural as interpreted from the context.

[0030] In this instruction manual, room temperature is based on approximately 20°C, and ambient temperature is based on approximately 25°C.

[0031] In this specification, the text and / or numbers listed together with the name of the compound refer to the abbreviation of the compound name.

[0032] The term "resin" as used in this specification is interpreted to include both the resin itself and compounds derived from it. For example, the term "polyether block amide copolymer resin" as used in this specification refers to polyether block amide copolymer resin and its derivatives.

[0033] In this specification, the amount of hydroxyl groups is evaluated by measuring the amount of vinyl groups bound to the hydroxyl groups of the polyvinyl acetal resin according to the method of JIS K6728.

[0034] Sunlight, as natural light, includes not only visible light but also infrared and ultraviolet rays. The ultraviolet rays in sunlight that reach the Earth's surface are divided into UVA (Ultraviolet A), with wavelengths from 315 nm to 400 nm, and UVB (Ultraviolet B), with wavelengths from 280 nm to 315 nm. UVA and UVB are short-wavelength, high-energy rays. When these rays irradiate a thin film, photochemical reactions may occur, generating free radicals or causing surface molecules to bind. Depending on the extent, this reaction may cause surface hardening and cracking in the polymer material of the thin film, raising concerns about reduced material strength and changes in yellowness.

[0035] After trying various methods, the inventors of the embodiments confirmed that methods such as mixing polyether block amide copolymer resin with polyvinyl acetal resin as a dissimilar resin and thinning it into a film could substantially suppress changes in yellowness, and proposed this as an embodiment.

[0036] The implementation method will be described in more detail below.

[0037] Optical properties of thin films To achieve the above objectives, the film according to the embodiments includes a polyether block amide copolymer resin and a polyvinyl acetal resin.

[0038] The change in yellowness (dYI) of a film after exposure to light for a given time is represented by the following formula 1.

[0039] [Formula 1] dYI = YI_2 - YI_1 In Equation 1 above, YI_1 above represents the yellowness value of the thin film before it was exposed to the aforementioned light. YI_2 is the yellowness value of the film after being exposed to the light for the aforementioned exposure time.

[0040] The aforementioned light has a wavelength of 310 nm and an output of 0.68 W / m. 2 When the exposure time is 120 hours, the yellowness change value (dYI) of the above film can be less than 2.

[0041] Specifically, the light mentioned above has a wavelength of 310 nm and an output of 0.68 W / m. 2 When exposed to light for 120 hours, the yellowness change value (dYI) of the film can be below 2, below 1.8, below 1.5, below 1, or below 0.5. The yellowness change value of the film can be above -1.

[0042] The aforementioned light has a wavelength of 310 nm and an output of 0.68 W / m. 2 When the exposure time is 168 hours, the yellowness change value (dYI) of the above film can be below 2.2.

[0043] Specifically, the light mentioned above has a wavelength of 310 nm and an output of 0.68 W / m. 2 When exposed to light for 168 hours, the yellowness change value (dYI) of the film can be below 2.2, below 2, below 1.5, below 1, below 0.8, or below 0.6. The yellowness change value of the film can be above -1.

[0044] The aforementioned light has a wavelength of 310 nm and an output of 0.68 W / m. 2 When exposed to light for 336 hours, the yellowness change value (dYI) of the above-mentioned film can be below 4. Alternatively, the yellowness change value of the above-mentioned film can be above -1.

[0045] Specifically, the light mentioned above has a wavelength of 310 nm and an output of 0.68 W / m. 2When exposed to light for 336 hours, the yellowness change value (dYI) of the film can be below 4, below 3.5, below 3, below 2.5, below 2, below 1.5, below 1, or below 0.6. The yellowness change value of the film can be above -1.

[0046] The aforementioned light has a wavelength of 310 nm and an output of 0.68 W / m. 2 When the exposure time is 672 hours, the yellowness change value (dYI) of the above film can be less than 5.

[0047] Specifically, the light mentioned above has a wavelength of 310 nm and an output of 0.68 W / m. 2 When exposed to light for 672 hours, the yellowness change value (dYI) of the film can be below 5, below 4.5, below 4, below 3.5, below 3, below 2.5, below 2, below 1.5, below 1, or below 0.4. The yellowness change value of the film can be above -1.

[0048] Even after prolonged exposure to UVB, this film exhibits minimal change in yellowness, maintaining excellent optical properties over extended periods. Furthermore, it enhances the durability and quality of products utilizing this film.

[0049] The aforementioned light has a wavelength of 340nm and an output of 0.72W / m. 2 When the exposure time is 1200 hours, the yellowness change value (dYI) of the above film can be less than 1.

[0050] Specifically, the light mentioned above has a wavelength of 340nm and an output of 0.72W / m. 2 When exposed to light for 1200 hours, the yellowness change value (dYI) of the film can be below 1, below 0.3, or below 0.25. Alternatively, the yellowness change value of the film can be above -1.

[0051] Even after prolonged exposure to UVA, this film exhibits minimal change in yellowness, maintaining excellent optical properties over extended periods. Furthermore, it enhances the durability and quality of products utilizing this film.

[0052] The above-mentioned thin film has an output of 0.68 W / m at a wavelength of 310 nm. 2 After exposure to light for 336 hours, the yellowness can be below 2.15. The aforementioned yellowness can be above -1.

[0053] The above-mentioned thin film has an output of 0.68 W / m at a wavelength of 310 nm. 2 After exposure to light for 672 hours, the yellowness can be below 1.8. The aforementioned yellowness can be above -1.

[0054] The aforementioned thin film exhibits an output of 0.72 W / m at a wavelength of 340 nm. 2 After exposure to light for 336 hours, the yellowness can be below 1.6. The aforementioned yellowness can be above -1.

[0055] The aforementioned thin film exhibits an output of 0.72 W / m at a wavelength of 340 nm. 2 After exposure to light for 672 hours, the yellowness can be below 1.7 or 1.6. The above yellowness can be above -1.

[0056] The aforementioned thin film exhibits an output of 0.72 W / m at a wavelength of 340 nm. 2 After exposure to light for 1200 hours, the yellowness can be below 1.7, below 1.6, or below 1.55. The above yellowness can be above -1.

[0057] The phenomenon of a thin film aging, leading to surface hardening and cracking in polymer materials, resulting in loss of elasticity and tearing, is called braking. Specifically, this can be observed with the naked eye as thin film tearing, surface cracking, and other phenomena.

[0058] The above-mentioned film was tested using a Q-LAB QUV weathering tester at a temperature of 0.68 W / m. 2 Even after being irradiated with UVB light at a wavelength of 310nm for 288 hours, the film does not break. This film does not crack even after prolonged exposure to UVB, maintaining excellent mechanical properties for an extended period and improving the durability and quality of products using this film.

[0059] When polyether block amide copolymer resin is used alone in films, an increase in haze is sometimes observed when exposed to air for extended periods in high-temperature and high-humidity environments. Based on repeated experiments, the inventors determined that this phenomenon is caused by the migration of unreacted polyether monomers (or oligomers) within the film.

[0060] In order to suppress this haze change, the inventors, after trying various methods, confirmed that methods such as mixing polyether block amide copolymer resin with dissimilar resins including polyvinyl acetal resin and thinning it into a film can substantially suppress the haze change.

[0061] The haze value of the aforementioned film at room temperature can be 3% or less. Specifically, the haze value of the aforementioned film at room temperature can be 2.5% or less or 2% or less. The haze value of the aforementioned film at room temperature can be 0% or more or 0.1% or more. When preparing the aforementioned film with such haze values, it is possible to ensure transparency at a level suitable for optical applications.

[0062] The haze value of the above-mentioned film after being placed at 60°C for 7 days can be below 3%. Specifically, the haze value of the above-mentioned film after being placed at 60°C for 7 days can be below 2.5% or below 2%. The haze value of the above-mentioned film after being placed at 60°C for 7 days can be above 0% or above 0.1%.

[0063] The difference in haze value of the aforementioned film before and after being placed at 60°C for 7 days can be less than 1%. Specifically, the difference in haze value of the aforementioned film before and after being placed at 60°C for 7 days can be less than 0.5%, less than 0.3%, less than 0.1%, less than 0.05%, less than 0.01%, or less than 0.001%. The difference in haze value of the aforementioned film before and after being placed at 60°C for 7 days can be greater than 0% or greater than 0.0001%. Under these conditions, even if the aforementioned film is exposed to a film application environment with a temperature higher than room temperature for a long time, the change in haze value is small, thus minimizing the degradation of optical performance.

[0064] Composition of thin films The film includes i) a polyether block amide copolymer resin; and ii) a polyvinyl acetal resin or a polyvinyl alcohol resin.

[0065] Polyether block amide copolymer resins can contain both polyamide and polyether regions. The polyamide regions can include semi-crystalline regions, exhibiting relatively rigid properties. The polyether regions can include amorphous regions, exhibiting relatively flexible properties. When the polyamide and polyether regions are arranged at appropriate levels within the polymer chains of the film, a film possessing both excellent mechanical strength and flexibility can be provided.

[0066] Polyether block amide copolymers can be formed by condensation polymerization of polyether blocks containing reactive ends and polyamide blocks containing reactive ends.

[0067] Polyether block amide copolymers can be formed by combining polyamides containing more than 2 carboxyl groups in the molecule with polyethers containing more than 2 hydroxyl groups in the molecule.

[0068] Polyether block amide copolymers can be condensation polymers containing polyamide blocks with dicarboxyl groups at the ends and polyoxyalkylene blocks with diamine groups at the ends. The polyoxyalkylene blocks can be obtained by cyanoethylation and hydrogenation of aliphatic α,ω-dihydroxylate polyoxyalkylene blocks known as polyether diols.

[0069] Polyether block amide copolymers can be condensation polymers containing polyamide blocks with dicarboxylic acid ends and polyether glycol blocks. In this case, the polyether block amide is a polyether ester amide.

[0070] Exemplarily, a polyamide block comprising a dicarboxylic acid chain terminus may be contained in a polyamide precursor condensate in the presence of a chain-restricted dicarboxylic acid. Exemplarily, a polyamide block comprising a diamine chain terminus may be contained in a polyamide precursor condensate in the presence of a chain-restricted diamine.

[0071] For example, the polyamide block containing a dicarboxylic acid chain terminus can be a condensation polymer of an α,ω-aminocarboxylic acid, lactam, or dicarboxylic acid with a diamine in the presence of a chain-restricted dicarboxylic acid. Polyamide 12 or polyamide 6 can be used as the aforementioned polyamide block.

[0072] Polyether block amide copolymers may include blocks having a randomly distributed unit structure. Exemplarily, the following three types of polyamide blocks may be applied.

[0073] As a first type, the polyamide block may comprise a condensation polymer of a dicarboxylic acid and an aliphatic or arylaliphatic diamine. The dicarboxylic acid may have 4 to 20 carbon atoms, or 6 to 18 carbon atoms. The aliphatic or arylaliphatic diamine may have 2 to 20 carbon atoms, or 6 to 14 carbon atoms.

[0074] Dicarboxylic acids can be, for example, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexyldicarboxylic acid, 1,4-butanedioic acid, adipic acid, azelaic acid, suberic acid, sebacic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, terephthalic acid, isophthalic acid, haphthalenedicarboxylic acid, and dimerized fatty acids.

[0075] The diamine can be, for example, 1,5-tetramethylenediamine, 1,6-hexamethylenediamine, 1,10-decamethylenediamine, 1,12-dodecamethylenediamine, trimethyl-1,6-hexamethylenediamine, 2-methyl-1,5-pentamethylenediamine, and bis(3-methyl-4-aminocyclohexyl)methane isomers. Bis(3-methyl-4-aminocyclohexyl)methan (BMACM), 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), bis(para-aminocyclohexyl)methane (PACM), isophoronediamine (IPD), 2,6-bis(aminomethyl)norbornane (BAMN), piperazine (Pip), meta-xylylenediamine (MXD), and paraxylylenediamine (PXD), etc.

[0076] The first type of polyamide block may include PA 412, PA 414, PA 418, PA 610, PA 612, PA614, PA 618, PA 912, PA 1010, PA 1012, PA 1014, PA 1018, MXD6, PXD6, MXD10, or PXD10.

[0077] The second type of polyamide block may comprise a condensation polymer of at least one α,ω-aminocarboxylic acid and / or at least one lactam having 6 to 12 carbon atoms in the presence of a dicarboxylic acid or diamine having 4 to 12 carbon atoms.

[0078] Examples of lactams include caprolactam, oenantholactam, and laurolactam. Examples of the aforementioned α,ω-aminocarboxylic acids include aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acids.

[0079] The second type of polyamide block may include polyamide 11, polyamide 12 or polyamide 6.

[0080] The third type of polyamide block may include a condensation polymer of at least one α,ω-aminocarboxylic acid (or at least one lactam), at least one diamine, and at least one dicarboxylic acid. In this case, the polyamide block can be prepared by condensation polymerization of the diamine, diacid, and comonomer (or multiple comonomers) as shown below.

[0081] As a diamine, linear aliphatic diamines, aromatic diamines, and diamines having X carbon atoms can be used. As the aforementioned diacid, dicarboxylic acids and acids having Y carbon atoms can be used. One or more comonomers (Z) can be selected from lactams having Z carbon atoms, α,ω-aminocarboxylic acids, and mixtures of at least one diamine having X1 carbon atoms and at least one dicarboxylic acid having Y1 carbon atoms, which are substantially contained in equimolar amounts. However, (X1, Y1) is different from (X, Y) mentioned above.

[0082] Based on the overall composition of the combined polyamide precursor monomers, the content of one or more comonomers (Z) can be less than 50% by weight, less than 20% by weight, or less than 10% by weight.

[0083] The third type of condensation reaction can be carried out in the presence of a chain limiting agent selected from dicarboxylic acids. As a chain limiting agent, a dicarboxylic acid having Y carbon atoms can be used, which can be introduced in stoichiometric excess relative to at least one of the aforementioned diamines.

[0084] As a third type of alternative, the polyamide block may optionally contain, in the presence of a chain restrictor, two or more α,ω-aminocarboxylic acids having 6 to 12 carbon atoms, or two or more lactams, or lactams and aminocarboxylic acids with different numbers of carbon atoms.

[0085] Aliphatic α,ω-aminocarboxylic acids can be, for example, aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, etc.

[0086] Lactams can be, for example, caprolactam, heptalactam, laurolactam, etc.

[0087] Aliphatic diamines can be, for example, hexamethylenediamine, dodecamethylenediamine, trimethylhexamethylenediamine, etc.

[0088] Alicyclic diacids can be, for example, 1,4-cyclohexanedicarboxylic acid.

[0089] Aliphatic diacids can include, for example, succinic acid, adipic acid, azelaic acid, octanoic acid, sebacic acid, dodecanedicarboxylic acid, dimer fatty acids (with a dimerization rate of 98% or higher; hydrogenated; sold under the trademarks Pripol of Uniqema or Empol of Henkel), polyoxyethylene-α,ω-diacids, etc.

[0090] Aromatic diacids can be, for example, terephthalic acid, isophthalic acid, etc.

[0091] Alicyclic diamines can be isomers of, for example, bis(3-methyl-4-aminocyclohexyl)methane (BMACM) and 2,2-bis(3-methyl-4-aminocyclohexyl)propane (BMACP), bis(p-aminocyclohexyl)methane (PACM), etc.

[0092] Diamines can be, for example, isophorone diamine (IPD), 2,6-bis(aminomethyl)norbornene (BAMN), piperazine, etc. Examples of aryl aliphatic diamines include, but are not limited to, m-phenylenediamine (MXD) and p-phenylenediamine (PXD).

[0093] Examples of the third type of polyamide blocks include PA 66 / 6, PA 66 / 610 / 11 / 12, etc. In PA 66 / 6, the 66 represents a hexamethylenediamine unit condensed with adipic acid, and the 6 represents a unit introduced by the condensation of caprolactam.

[0094] In PA 66 / 610 / 11 / 12, 66 represents a hexamethylenediamine unit condensed with adipic acid, 610 represents a hexamethylenediamine unit condensed with sebacic acid, 11 represents a unit introduced by condensation with aminoundecanoic acid, and 12 represents a unit introduced by condensation with laurolactam.

[0095] As a polyether block, it is preferably selected from, for example, at least one polyalkylene ether polyol, particularly polyethylene glycol (PEG), polypropylene glycol (PPG), polytrimethylene glycol (PO3G), polytetramethylene glycol (PTMG), and mixtures thereof or copolymers thereof. The polyether block may contain a polyoxyethylene sequence with an NH2 chain terminus, which can be introduced by cyanoacetylation of an aliphatic α,ω-dihydroxy polyoxyethylene sequence referred to as a polyether glycol. Specifically, Jeffamine (e.g., Jeffamine from Huntsman Corporation) can be used. ® (D400, D2000, ED2003 or XTJ542).

[0096] The aforementioned at least one polyether block may preferably contain at least one polyether selected from, for example, polyalkylene ether polyols such as PEG, PPG, PO3G, PTMG, polyethers containing NH2 at the chain end and containing a polyoxyethylene sequence, copolymers of their random arrangement and / or block arrangement (ether copolymers), and mixtures thereof.

[0097] The polyether block can be generated from any of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and combinations thereof.

[0098] Polyether blocks can be copolymerized with carboxyl-terminated polyamide blocks to form polyether block amides. The polyether blocks can be amination followed by condensation with carboxyl-terminated polyamide blocks to form polyether block amides. Polyether blocks can be mixed with polyamide precursors and chain restrictors to form polyether block amides containing statistically dispersed units.

[0099] Examples of polyethers include polyethylene glycol (PEG), polypropylene glycol (PPG), or polytetramethylene glycol (PTMG). Polytetramethylene glycol is also known as polytetrahydrofuran (PTHF). Polyether blocks can be introduced into the polyether block amide chain in the form of diols or diamines; these polyether blocks are referred to as PEG blocks, PPG blocks, or PTMG blocks, respectively.

[0100] The number-average molar mass of the polyamide block can be from 300 g / mol to 15,000 g / mol, or from 600 g / mol to 5,000 g / mol. The number-average molar mass of the polyether block can be from 100 g / mol to 6,000 g / mol, or from 200 g / mol to 3,000 g / mol.

[0101] The number-average molar mass ratio of polyamide blocks to polyether blocks in a polyether block amide copolymer can be from 1:0.25 to 1:1, and the number-average molar masses of the polyamide blocks and polyether blocks in the copolymer can be 1,000 / 1,000, 1,300 / 650, 2,000 / 1,000, 2,600 / 650, or 4,000 / 1,000, respectively.

[0102] The content of the polyether blocks relative to the total weight of the polyether block amide copolymer may be 10% by weight or more. The content may be 40% by weight or more. The content may be 60% by weight or more. The content may be 80% by weight or less.

[0103] The content of the polyamide blocks relative to the total weight of the polyether block amide copolymer can be 20% by weight or more. The content can be 40% by weight or more. The content can be 90% by weight or less. The content can be 60% by weight or less.

[0104] Films with this characteristic can simultaneously control elasticity and hardness. This results in excellent long-term durability and provides stable protection of the coated surface from external impacts.

[0105] The above content can be interpreted as exhibiting a statistical distribution within the polymer chain.

[0106] Examples of polyether block amide copolymers include Arkema's Pebax. ® Pebax ® Rnew ® VESTAMID from Evonik Industries, Inc. ® E, etc., but not limited to these.

[0107] The branches of polyvinyl acetal resin or polyvinyl alcohol resin contain hydroxyl groups.

[0108] The degree of polymerization of polyvinyl acetal resin or polyvinyl alcohol resin can be below 3,500.

[0109] Polyvinyl acetal resin or polyvinyl alcohol resin with a low degree of polymerization can be used to form coating films, etc., while those with a certain degree of polymerization or higher can be used for film production by extrusion or other methods. Exemplarily, in one embodiment, it is used in combination with a polyether block amide copolymer resin. In this embodiment, both those with a low degree of polymerization and those with a certain degree of polymerization or higher can be used.

[0110] Polyvinyl acetal resin can be obtained by synthesizing polyvinyl alcohol and aldehyde.

[0111] For example, the degree of polymerization of the polyvinyl alcohol resin described above can be from 200 to 3,500. Alternatively, the polyvinyl alcohol acetal resin described above can be obtained by acetalizing a polyvinyl alcohol resin with a degree of polymerization of 200 to 3,500 with an aldehyde.

[0112] For example, the degree of polymerization of the above-mentioned polyvinyl alcohol resin may be from 1,600 to 3,000. Alternatively, the above-mentioned polyvinyl alcohol acetal resin may be obtained by acetalizing a polyvinyl alcohol resin with a degree of polymerization of 1,600 to 3,000 with an aldehyde.

[0113] For example, the degree of polymerization of the polyvinyl alcohol resin described above may be from 1,700 to 2,500. Alternatively, the polyvinyl alcohol acetal resin described above may be obtained by acetalizing a polyvinyl alcohol resin with a degree of polymerization of 1,700 to 2,500 with an aldehyde.

[0114] When this resin is applied to films, the mechanical properties of the films can be significantly improved.

[0115] The aldehyde mentioned above can be any one selected from the group consisting of n-butyraldehyde, isobutyraldehyde, n-pentanaldehyde, 2-ethylbutyraldehyde, n-hexanaldehyde, and their blends. When n-butyraldehyde is used as the aldehyde mentioned above, the prepared polyvinyl butyral resin has refractive index characteristics similar to those of glass, and thus can have excellent optical properties.

[0116] Polyvinyl acetal resin or polyvinyl alcohol resin contains hydroxyl groups in its side chain. The hydroxyl content in the aforementioned polyvinyl acetal resin or polyvinyl alcohol resin can be 2% or more by weight, 5% or more by weight, 8% or more by weight, 10% or more by weight, 15% or more by weight, 16% or more by weight, or 19% or more by weight. Furthermore, the hydroxyl content in the aforementioned polyvinyl acetal resin or polyvinyl alcohol resin can be 60% by weight, 50% by weight, 40% by weight, or less than 30% by weight.

[0117] The acetyl content of the polyvinyl acetal resin can be 0.01% by weight or more, 1.5% by weight or more, 3% by weight or more, 5% by weight or more, or 10% by weight or more. Alternatively, the acetyl content of the aforementioned polyvinyl acetal resin can be 20% by weight or less, 15% by weight or less, or 12% by weight or less.

[0118] Using a resin with these properties can improve miscibility with the plasticizers described later and effectively suppress the reduction in optical properties of the film caused by haze changes. This is believed to be because the hydroxyl groups arranged on the branches inhibit the migration of unreacted polyether monomers (or oligomers), thereby helping to suppress the induction of haze changes.

[0119] The aforementioned film may include a ratio of 2.5 parts by weight or less of the sum of the i) polyether block amide copolymer resin and the ii) polyvinyl acetal resin and polyvinyl alcohol resin relative to 1 part by weight. Specifically, as described above, the content of the sum of the polyvinyl acetal resin and polyvinyl alcohol resin relative to 1 part by weight of the aforementioned polyether block amide copolymer resin may be 2.5 parts by weight or less, 2.3 parts by weight or less, 2 parts by weight or less, 1.8 parts by weight or less, 1.6 parts by weight or less, 1.5 parts by weight or less, 1 part by weight or less, 0.67 parts by weight or less, or 0.5 parts by weight or less. In the aforementioned film, the content of the sum of the polyvinyl acetal resin and polyvinyl alcohol resin relative to 1 part by weight of the aforementioned polyether block amide copolymer resin may be 0.001 parts by weight or more, 0.01 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more, or 0.3 parts by weight or more.

[0120] If the above-mentioned film is prepared in the proportions described above, the migration of unreacted polyether can be minimized, thereby helping to effectively suppress the reduction of the film's optical properties caused by haze changes.

[0121] The aforementioned film may also include a plasticizer. The aforementioned film is based on 100 parts by weight of a base resin consisting of i) a polyether block amide copolymer resin and ii) a polyvinyl acetal resin and a polyvinyl alcohol resin, including the following amounts of plasticizer.

[0122] Based on 100 parts by weight of the above-mentioned base resin, it may include 0.1 parts by weight or more, 0.3 parts by weight or more, 0.5 parts by weight or more, or 1 part by weight or more of plasticizer. In addition, based on 100 parts by weight of the above-mentioned base resin, it may include 20 parts by weight or less, 17 parts by weight or less, 15 parts by weight or less, or 10 parts by weight or less of plasticizer.

[0123] The aforementioned plasticizer can be applied in a predetermined proportion relative to the content of the aforementioned polyvinyl acetal resin. The content of the aforementioned plasticizer relative to 100 parts by weight of the aforementioned polyvinyl acetal resin can be 1 part by weight or more, 5 parts by weight or more, 8 parts by weight or more, 10 parts by weight or more, 12 parts by weight or more, or 15 parts by weight or more. Alternatively, the content of the aforementioned plasticizer relative to 100 parts by weight of the aforementioned polyvinyl acetal resin can be 50 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, or 30 parts by weight or less.

[0124] The aforementioned plasticizer can be mixed with polyether block amide copolymer resin, polyvinyl acetal resin, and / or polyvinyl alcohol resin. In this case, dispersibility can be further improved.

[0125] The aforementioned plasticizer can be mixed with polyvinyl acetal resin first, and then mixed with polyether block amide copolymer resin.

[0126] Specifically, as the aforementioned plasticizer, a plasticizer selected from triethylene glycol bis(ethylene glycol) can be used. 2 Ethylhexanoate (3G8), tetraethylene glycol diheptanoate (4G7), triethylene glycol bis-2-ethylbutyrate (3GH), triethylene glycol bis-2-heptanoate (3G7), dibutoxyethoxyethyl adipate (DBEA), butyl carbitol adipate (DBEEA), dibutyl sebacate (DBS), dihexyl adipate (DHA), and combinations thereof, specifically, may include any one selected from triethylene glycol bis-2-ethylbutyrate, triethylene glycol di-2-ethylbutyrate, and di-2-ethylbutyrate. 2 Any one of the group consisting of ethylhexanoate, triethylene glycol bis-2-heptanoate, and combinations thereof, more specifically, triethylene glycol bis-heptanoate can be used. 2 Ethylhexanoate (3G8). This plasticizer exhibits excellent miscibility with polyvinyl acetal resins and can simultaneously improve workability and optical properties.

[0127] The aforementioned thin film may include a light absorber. By adjusting the content of the light absorber in the thin film, the degradation of the film's optical and mechanical properties caused by ultraviolet exposure can be effectively reduced. Furthermore, it helps suppress the migration of the light absorber within the thin film, thus helping to prevent excessive increases in the film's yellowness.

[0128] The film, based on 100 parts by weight of the aforementioned base resin, may include 0.05 to 5 parts by weight of the aforementioned light absorber. The film, based on 100 parts by weight of the aforementioned base resin, may include 0.08 parts or more, 0.1 parts or more, or 0.2 parts or more of the aforementioned light absorber. The film, based on 100 parts by weight of the aforementioned base resin, may include less than 5 parts by weight, less than 3 parts by weight, or less than 2 parts by weight of the aforementioned light absorber. In this case, the yellowing and hardening rate of the film can be effectively slowed down. Furthermore, since the migration of the light absorber is suppressed, the appearance of the film can be prevented from becoming contaminated.

[0129] The aforementioned light absorber may include any one selected from the group consisting of benzotriazole compounds, oxaloylaniline compounds, hydroxybenzophenone compounds, hydroxyphenyltriazine compounds, benzoic acid ester compounds, and combinations thereof. This compound exhibits excellent compatibility with polyether block amide copolymer resins and effectively absorbs ultraviolet light, thereby stably preventing film degradation.

[0130] For example, BASF's Tinuvin 234, Tinuvin 312, Tinuvin 329, Tinuvin P, Tinuvin 1130, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 571, Tinuvin 99-DW, Tinuvin 1600, Tinuvin 1577, etc., can be used as light absorbers.

[0131] The aforementioned films may further include additives commonly used in the film industry. Examples of such additives include lubricants, anti-blocking agents, heat stabilizers, antistatic agents, and impact modifiers.

[0132] The thickness of the aforementioned film can be 1,000 µm or less. Specifically, the thickness of the aforementioned film can be 500 µm or less, 250 µm or less, or 150 µm or less. The thickness of the aforementioned film can be 1 µm or more, 10 µm or more, 20 µm or more, 30 µm or more, 40 µm or more, or 50 µm or more, and can be 100 µm or more. When the aforementioned film is prepared with such thickness, it is possible to provide a thin and lightweight film that also possesses excellent impact resistance and other properties, as well as low haze.

[0133] The film in this embodiment can be an extruded film. Extruded films offer the advantages of easier mass production and the ability to form laminated films that further include other layers. When preparing an extruded film, film thickness control is easier, and compared to casting methods, it is advantageous to prepare relatively thick films with good overall thickness control. For example, the thickness of the extruded film can be 80µm or more, 90µm or more, or 100µm or more.

[0134] The film of the embodiment can be a film that further includes a plasticizer. The plasticizer can adjust the modulus of the film. Specifically, a film including a plasticizer can reduce the modulus, which can improve the workability of the surface protective film.

[0135] Applications of thin films The aforementioned film can be a surface protection film.

[0136] The aforementioned surface protective film can be applied to automobiles, aircraft, electronic products, furniture, etc. (hereinafter referred to as articles). The surface of the articles may include at least a portion of a coated surface with paint or the like. The aforementioned surface protective film can be attached to the coated surface to protect the coating of the articles from being peeled off.

[0137] The aforementioned surface protective film can be disposed on a substrate. This prevents the substrate from being exposed to the outside. Here, the substrate refers to at least a portion of the article.

[0138] The aforementioned substrate can be a substrate on which a coating has been formed. The aforementioned surface protective film can be disposed on the substrate on which the coating has been formed. This prevents the coating from being exposed to the outside, thereby preventing damage to the coating.

[0139] As a method for preparing the film, conventional film preparation methods can be applied. For example, the film can be prepared by extrusion, but is not limited thereto. Specifically, a composition corresponding to the film composition can be mixed and extruded in an extruder, and then sheeted in a casting roll or the like to prepare the film of the embodiment.

[0140] The following detailed description uses specific embodiments. These embodiments are merely examples to aid in understanding the invention, and the scope of the invention is not limited thereto.

[0141] Preparation example: Thin film preparation Example 1: PEBAX was applied as a polyether block amide copolymer resin composition at a weight of 69.1 parts. ® 40R53 (contains approximately 46% by weight of PA11 residues as amide residues and approximately 54% by weight of polytetramethylene glycol residues). The above-mentioned PEBAX ®40R53 is a commercially available polyether block amide resin, abbreviated as 40R53. The above resin was purchased from and used by Arkema France. As a polyvinyl alcohol acetal resin composition, polyvinyl alcohol with a degree of polymerization of 1700 and a degree of saponification of 99 and n-butyraldehyde were added, and a conventional synthesis process was carried out. Polyvinyl alcohol butyraldehyde resin (PVB) with a hydroxyl content of 20.3% by weight, a butyraldehyde group content of 78.9% by weight, and an acetyl group content of 0.8% by weight, and triethylene glycol bismuth subcarbonate as a plasticizer were added. 2 Ethylhexanoate (3G8) was applied in 25.8 parts by weight and 4.2 parts by weight, respectively. Furthermore, BASF's Tinuvin 1600 was applied as a light absorber in 0.9 parts by weight. The above-mentioned polyether block amide copolymer resin composition, polyvinyl acetal resin composition, and light absorber were mixed and melt-extruded using an extruder owned by SK Microworks Solutions Co., Ltd. to prepare a film. PET protective films were applied to both sides of the film for storage.

[0142] Example 2: PEBAX was used as the polyether block amide copolymer resin composition in Example 1. ® 35R53 (contains approximately 31% by weight of PA11 residues as amide residues and approximately 69% by weight of polytetramethylene glycol residues). The above-mentioned PEBAX ® 35R53 is a commercially available polyether block amide resin, abbreviated as 35R53. The above resin was purchased from and used by Arkema, France. Other contents are listed in Table 1 below.

[0143] Examples 3 and 4 were prepared using the same method as in Example 1, with the compositions and contents presented in Table 1 below.

[0144] Comparative Example 1: Except that the polyether block amide copolymer resin composition 40R53 in Example 1 was used in 100 parts by weight and PVB was not included, the film was prepared in the same manner as in Example 1.

[0145] In Comparative Example 2, a commercially available thermoplastic polyurethane film (TPU film), namely Argotec 49510 from SWM Corporation, was purchased and applied.

[0146] The process preparation conditions for each embodiment and comparative example are shown in Table 1 below.

[0147] Evaluation example: Measurement of changes in yellowness and haze The yellowness of the films of each example and comparative example was measured in D65 / 10 mode according to ASTM E313.

[0148] Subsequently, the above-mentioned film was subjected to a weathering tester from Q-Lab at a temperature of 0.68 W / m. 2 The film was irradiated with UVB light at a wavelength of 310 nm. The yellowness of the film was measured based on the cumulative irradiation time. The method for measuring the yellowness value after irradiation was the same as that for the measurement before irradiation.

[0149] Based on the measured values, the differences between YI_1, YI_2, and dYI were calculated.

[0150] Furthermore, when the above-mentioned film was irradiated with UVA / 340nm wavelength light using Q-Lab's QUV weathering tester, the output was 0.72W / m. 2 The yellowness of the film was measured based on the cumulative time of light exposure. The method for measuring the yellowness value after light exposure was the same as that for the measurement before light exposure.

[0151] Based on the measured values, the differences between YI_1, YI_2, and dYI were calculated.

[0152] Furthermore, the haze of the above samples was measured using a haze meter according to ASTM D 1003. The haze of the film was measured based on the cumulative time of light exposure. The method for measuring haze values ​​after light exposure was the same as that for measurements before light exposure. Based on the measured values, the difference in haze values ​​before and after being placed at 60°C for 7 days was calculated.

[0153] The measurement results of each embodiment and comparative example are shown in Tables 2 to 5 below.

[0154] Evaluation example: Measurement of changes in yellowness and haze The UVB lamp used is the G15T82 from Sankyo Denki Co., Ltd., with a power of 0.68W / m². 2 The output light was used to irradiate the films of each embodiment and comparative example with UVB-313 EL light. The cracking phenomenon of the films was observed according to the cumulative irradiation time.

[0155] The measurement results of each embodiment and comparative example are disclosed in Table 6 below.

[0156] [Table 1]

[0157] [Table 2]

[0158] * YI_1 is the yellowness value of the film before light irradiation.

[0159] [Table 3]

[0160] * dYI = YI_2 - YI_1 [Table 4]

[0161] * YI_1 is the yellowness value of the film before light irradiation.

[0162] [Table 5]

[0163] * dYI = YI_2 - YI_1 [Table 6]

[0164] Referring to Tables 2 and 3 above, the dYI values ​​of Examples 1 to 4 and Comparative Example 1 are below 1, while those of Comparative Example 2 are above 1. This indicates that the films of the Examples exhibit superior resistance to yellowing not only compared to the urethane film of Comparative Example 2, but also compared to the film using a polyether block amide copolymer resin alone.

[0165] Referring to Tables 4 and 5 above, the results of the examples are also superior to those of the comparative examples in terms of durability when different wavelengths of ultraviolet light are applied.

[0166] Referring to Table 6 above, in the UVB durability test, the samples of the examples did not break, but Comparative Example 1 did break. Although the polyurethane film of Comparative Example 2 also did not break, as mentioned above, it exhibited insufficient properties in terms of yellowing rate of change.

[0167] While the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto. Various modifications and improvements made by those skilled in the art using the basic concepts of the present invention as defined in the appended claims also fall within the scope of the present invention.

Claims

1. A thin film, characterized in that, include: i) Polyether block amide copolymer resin; as well as ii) Polyvinyl acetal resin or polyvinyl alcohol resin, The change in yellowness (dYI) of a thin film after exposure to light for a given time is expressed by the following equation 1. The light mentioned above has a wavelength of 310nm and an output of 0.68W / m. 2 light, The exposure time mentioned above is 120 hours. The above-mentioned yellowness variation value is below 2; [Formula 1] dYI = YI_2 - YI_1 In Equation 1 above, YI_1 above represents the yellowness value of the thin film before it was exposed to the aforementioned light. YI_2 is the yellowness value of the film after being exposed to the light for the aforementioned exposure time.

2. The thin film according to claim 1, characterized in that, The light mentioned above has a wavelength of 340nm and an output of 0.72W / m. 2 The light exposure time was 1200 hours, and the yellowness change value was less than 0.

3.

3. The thin film according to claim 1, characterized in that, The above-mentioned polyvinyl acetal resin or polyvinyl alcohol resin contains hydroxyl groups in its side chain.

4. The thin film according to claim 1, characterized in that, Based on 100 parts by weight of the sum of the above i) polyether block amide copolymer resin and ii) polyvinyl acetal resin or polyvinyl alcohol resin, the film includes less than 20 parts by weight of plasticizer.

5. The thin film according to claim 1, characterized in that, The difference in haze value before and after placing the product in a 60℃ oven for 7 days is less than 1%.

6. A thin film, characterized in that, include: i) Polyether block amide copolymer resin; as well as ii) Polyvinyl acetal resin or polyvinyl alcohol resin, The change in yellowness (dYI) of a thin film after exposure to light for a given time is expressed by the following equation 1. The light mentioned above has a wavelength of 340nm and an output of 0.72W / m. 2 light, The aforementioned exposure time was 1200 hours. The above-mentioned yellowness change value is below 0.3; [Formula 1] dYI = YI_2 - YI_1 In Equation 1 above, YI_1 above represents the yellowness value of the thin film before it was exposed to the aforementioned light. YI_2 is the yellowness value of the film after being exposed to the light described above.

7. The thin film according to claim 6, characterized in that, Based on 100 parts by weight of the sum of the above-mentioned polyether block amide copolymer resin and polyvinyl acetal resin, the above-mentioned film further includes less than 5 parts by weight of light absorber.

8. The thin film according to claim 6, characterized in that, At 0.68W / m 2 Even after being irradiated with UVB light at a wavelength of 310nm for 288 hours, no breakage occurred.

9. A surface protective film, characterized in that... ， The thin film according to claim 1 or claim 6 is disposed on a substrate, wherein the substrate is a substrate on which a coating film is formed.

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