Film

Abstract

A film according to an embodiment comprises a first polymer resin and a second polymer resin which are heterogeneous resins, wherein the first polymer resin comprises a polyamide-based repeating unit and a polyether-based repeating unit, the second polymer resin comprises, at a branch, any one selected from the group consisting of a hydroxyl group, an acetal group, and a combination thereof, the tensile recovery rate at N% elongation is derived according to equation 1 below, and when N% is 60%, the tensile recovery rate of the film is 90% or more. [Equation 1] Tensile recovery rate (%) = (LfN-LiN) / (LfN-Li) wherein, in equation 1, LfN is the length of the film stretched at N% elongation, LiN is the length when the stretched film has been restored, and Li is the length of the film before stretching. The film of the embodiment can maintain excellent optical properties and excellent mechanical properties for a relatively long time.

Description

film

[0001] The embodiment relates to a film having excellent mechanical properties.

[0002] [Cross-reference to related applications]

[0003] This document claims priority to Korean Patent Application No. 10-2023-0129043, filed September 26, 2023, and Korean Patent Application No. 10-2023-0129042, filed September 26, 2023, the contents of which are incorporated herein by reference.

[0004]

[0005] To protect the paint surfaces applied to automobile exteriors, film laminates made of polyurethane (TPU) and polyvinyl chloride (PVC) have traditionally been attached. However, the elastic properties of these polyurethane and polyvinyl chloride film laminates can vary significantly depending on the external environment, particularly temperature, when applied to the paint surface, hindering the installation process. In winter, internal air conditioning and local heating devices are installed to separately manage the temperature of the area where work is being done. However, there are shortcomings in terms of convenience, completeness, and quality.

[0006] The background technology described above is technical information that the inventor possessed for the purpose of deriving the implementation example or acquired during the derivation process, and cannot necessarily be said to be publicly known technology disclosed to the general public prior to the application for the present invention.

[0007] Related prior art includes Korean Patent Publication No. 10-2012-0022141, “Release film for automotive paint protection film.”

[0008]

[0009] The purpose of the embodiment is to provide a film having excellent mechanical properties such as tensile recovery rate and strain rate.

[0010]

[0011] To achieve the above object, at least one embodiment is a film comprising a first polymer resin which is a heterogeneous resin; and a second polymer resin; wherein the first polymer resin comprises a polyamide-based repeating unit and a polyether-based repeating unit, and the second polymer resin comprises one selected from the group consisting of a hydroxyl group, an acetal group, and a combination thereof in a branch.

[0012] The tensile recovery rate at N % elongation is derived according to Equation 1 below, and when the N % is 60 %, the tensile recovery rate of the film can be 90% or more.

[0013] [Formula 1]

[0014] Tensile recovery rate (%) = (LfN - LiN) / (LfN - Li)

[0015] In the above equation 1, LfN is the length of the film stretched at an elongation of N%, LiN is the length of the stretched film when it is recovered, and Li is the length of the film before stretching.

[0016] The above film has a stress of 1 N / mm when the strain is 100%. 2 It could be as follows:

[0017] The film may have a haze value of 3% or less after being left at 60°C for 7 days.

[0018] The above film may have a tensile recovery rate of 75% or more when the above N % is 100%.

[0019] The above film may contain the polyether repeating unit in an amount of 10 wt% or more based on the total amount of the first polymer resin and the second polymer resin.

[0020] The tensile recovery rate reduction factor (20-40) between the above 20% elongation and the above 40% elongation is derived according to Equation 2 below, and the tensile recovery rate reduction factor (20-40) of the film may be 0.3 or less.

[0021] [Formula 2]

[0022] Tensile recovery rate reduction factor (20-40) =

[0023] In Equation 2, A 20 is the tensile recovery rate (%) of the above film at 20% elongation, and A 40 is the tensile recovery rate (%) of the above film at 40% elongation.

[0024] In order to achieve the above object, one or more embodiments include a polyether block amide copolymer resin; and a polyvinyl acetal resin, and the stress is 7 N / mm when the strain is 20%. 2 It could be as follows:

[0025] The above film has a stress when the strain is 100% minus the stress when the strain is 20%, which is 5 N / mm. 2 It could be as follows:

[0026] The above film may have a ratio of stress when the strain is 300% or more based on stress when the strain is 100%.

[0027] The above film may be a coating protection film.

[0028]

[0029] The film of the embodiment can maintain excellent optical properties and mechanical properties for a relatively long period of time. However, the effects of the embodiment are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

[0030]

[0031] The following is a detailed description of the implementation examples so that those skilled in the art can easily implement them. However, the implementation examples can be implemented in various different forms and are not limited to the embodiments described herein.

[0032] In a specification, when a configuration is said to "include" another configuration, this does not mean that it excludes other configurations, but rather that it may include other configurations, unless otherwise specifically stated.

[0033] In this specification, when it is said that a configuration is “connected” to another configuration, this includes not only the case where it is “directly connected” but also the case where it is “connected with another configuration in between.”

[0034] In this specification, the meaning of B being located on A means that B is located directly on A or that B is located on A with another configuration located in between, and is not limited to being interpreted as B being located on the surface of A.

[0035] In this specification, the term "combination of these" included in the expression in the Makushi format means one or more mixtures or combinations selected from the group consisting of the components described in the expression in the Makushi format, and means including one or more selected from the group consisting of the components.

[0036] In this specification, the description of “A and / or B” means “A, B, or A and B.”

[0037] In this specification, terms such as “first”, “second” or “A”, “B” are used to distinguish the same terms from each other unless otherwise specified.

[0038] In this specification, singular expressions are interpreted to include the singular or plural as interpreted in the context, unless otherwise specified.

[0039] In this specification, room temperature is defined as approximately 20°C, and ambient temperature is defined as approximately 25°C.

[0040] In this specification, letters and / or numbers used together with the name of a compound represent abbreviations for the name of the compound.

[0041] The resin described herein is interpreted to mean the resin itself and compounds derived from the resin. By way of example, the polyether block amide copolymer resin described herein means a polyether block amide copolymer resin and derivatives thereof.

[0042] In this specification, the evaluation of the hydroxyl group content was evaluated by measuring the ethylene group content to which the hydroxyl group of the polyvinyl acetal resin is bonded using a method compliant with JIS K6728.

[0043]

[0044] To achieve the above purpose, a film according to an embodiment includes a first polymer resin which is a heterogeneous resin; and a second polymer resin.

[0045] The above first polymer resin includes a polyamide repeating unit and a polyether repeating unit.

[0046] The above second polymer resin comprises one selected from the group consisting of hydroxyl groups, acetal groups, and combinations thereof in the branch.

[0047] The first polymer resin containing a polyamide repeating unit and a polyether repeating unit can provide the film with excellent characteristics such as durability and dimensional stability.

[0048] Surface protection films often involve stretching when applied to the object to which they are applied. The surface of the object being protected may contain curved or folded surfaces, and films applied to these areas inevitably undergo partial stretching.

[0049] When the first polymer resin described below is applied in the form of a film, a phenomenon is observed in which the film loses elasticity and does not recover to its original length when the elongation is increased.

[0050] If the tensile recovery rate of the film is reduced, the appearance of the object to which the film is applied may be damaged, and spaces such as air bubbles may be formed between the object and the film, making it difficult to sufficiently protect the object from the outside.

[0051] In order to suppress this decrease in tensile recovery rate, the inventors applied various methods and confirmed that the decrease in tensile recovery rate can be substantially suppressed by methods such as mixing different resins to form a film as in the embodiment.

[0052]

[0053] Below, the implementation example is described in more detail.

[0054]

[0055] Composition of the film

[0056] To achieve the above purpose, a film according to an embodiment includes a first polymer resin; and a second polymer resin.

[0057] The first polymer resin contains amide repeating units and polyether repeating units.

[0058] In the first polymer resin, the amide-based repeating unit can contribute to improving the hardness of the film. In the first polymer resin, the ester-based repeating unit can help impart flexibility and elasticity to the film.

[0059] The first polymer resin may contain 80 wt% or less of the amide-based repeating unit. The first polymer resin may contain 70 wt% or less of the amide-based repeating unit. The first polymer resin may contain 60 wt% or less of the amide-based repeating unit. The first polymer resin may contain 50 wt% or less of the amide-based repeating unit. The first polymer resin may contain 40 wt% or less of the amide-based repeating unit. The first polymer resin may contain 30 wt% or less of the amide-based repeating unit. The first polymer resin may contain 0 wt% or more of the amide-based repeating unit, and may contain 10 wt% or more of the amide-based repeating unit.

[0060] The above amide-based repeating unit may include an amide residue.

[0061] The first polymer resin may contain amide residues in an amount of 80 wt% or less, 70 wt% or less, 60 wt% or less, 50 wt% or less, 40 wt% or less, or 30 wt% or less. In addition, the first polymer resin may contain 0 wt% or more or 10 wt% or more of amide residues.

[0062] The above amide moiety may be, for example, an aliphatic amide moiety, a semi-aromatic amide moiety, a semi-crystalline polyamide moiety, an amorphous polyamide moiety, or a mixture thereof.

[0063] The first polymer resin may include a sum of aliphatic amide residues, semi-aromatic amide residues, semi-crystalline polyamide residues, and amorphous polyamide residues of 80 wt% or less, 70 wt% or less, 60 wt% or less, 50 wt% or less, 40 wt% or less, or 30 wt% or less. In addition, the first polymer resin may include a sum of aliphatic amide residues, semi-aromatic amide residues, semi-crystalline polyamide residues, and amorphous polyamide residues of 0 wt% or more or 10 wt% or more.

[0064] Aliphatic amide residues include, for example, polycaprolactam (PA 6), polyundecanamide (PA 11) residues, polylauryllactam (PA 12) residues, polybutylene adipamide (PA 46) residues, polyhexamethylene adipamide (PA 66) residues, polyhexamethylene azelamide (PA 69) residues, polyhexamethylene sebacamide (PA 610) residues, polyhexamethylene dodecanediamide (PA 612) residues, polydecamethylene dodecanediamide (PA 1012) residues, and polydecamethylene It may be a polydecamethylene sebacamide (PA 1010) residue, a polydodecamethylene dodecanediamide (PA 1212) residue, a polyamide copolymer PA 11 / NHUA residue, a PA BACM6 residue, a PA BACM10 residue, a PA BACM12 residue, a PA 6 / 66 residue, or a PA 6 / 12 residue.

[0065] The semi-aromatic amide residue may be a PA 6 / 6T residue, a PA 66 / 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 PA MXD10 residue.

[0066] The semi-crystalline polyamide residues can be PA 6 residues, PA 11 residues, PA 12 residues, PA 10.10 residues, PA 10.12 residues, PA 6.10 residues, or PA 6.12 residues.

[0067] Amorphous polyamide residues include polyamides such as polyhexamethylene isophthalamide (PA 6I) residues, polytrimethylhexamethylene terephthalamide (PA TMHMDAT) residues, and PA BACM12 residues; The amide copolymer may be a PA 6 / BMACPI moiety, a PA 6 / BAMNT moiety, a PA 11 / BMACMI moiety, a PA 11 / BMACMT / BMACMI moiety, a PA 11 / BACM.I / IPDA.I moiety, a PA 12 / BMACM.I moiety, a PA 12 / BACMT / BACMI moiety, a PA 12 / BMACMT / BACMI moiety, a PA 12 / BACMI / IPDAI moiety, a PA 6T / 6I / BACMI moiety, or a PA 6T / 6I / BACMT / BACMI moiety.

[0068] The first polymer resin may contain the polyether-based repeating unit in an amount of 10 wt% or more, 15 wt% or more, 20 wt% or more, 25 wt% or more, 30 wt% or more, or 35 wt% or more, based on the total sum of the first polymer resin and the second polymer resin. The first polymer resin may contain the polyether-based repeating unit in an amount of 50 wt% or less or 45 wt% or less, based on the total sum of the first polymer resin and the second polymer resin.

[0069] The above polyether repeating unit may include a tetramethylene oxide residue, an ethylene oxide residue, and / or a propylene oxide residue.

[0070] The first polymer resin may include a sum of the tetramethylene oxide residues, the ethylene oxide residues, and the propylene oxide residues of 20 wt% or more, 30 wt% or more, 40 wt% or more, 50 wt% or more, 60 wt% or more, or 70 wt% or more. The first polymer resin may include a sum of the tetramethylene oxide residues, the ethylene oxide residues, and the propylene oxide residues of 100 wt% or less or 90 wt% or less.

[0071] For example, the polyether repeating unit may include -CH2-CH2-CH2-CH2-O-, -CH2- CH2-O-, and / or -CH2(-CH2)-CH2-O-.

[0072] The first polymer resin may contain the sum of -CH2-CH2-CH2-CH2-O-, -CH2- CH2-O-, and -CH2(-CH2)-CH2-O- of 20 wt% or more, 30 wt% or more, 40 wt% or more, 50 wt% or more, or 70 wt% or more. The first polymer resin may contain the sum of -CH2-CH2-CH2-CH2-O-, -CH2- CH2-O-, and -CH2(-CH2)-CH2-O- of 100 wt% or less, or 90 wt% or less.

[0073] The first polymer resin may be a polyether block amide resin. When the first 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 40 wt%, less than 30 wt%, or less than 20 wt% based on the entire resin. In this case, the polyester film including the first polymer resin may be provided with properties of flexibility and elasticity.

[0074] The first polymer resin may be, for example, a polyether ester copolymer layer. The first polymer resin may be a polyether ester copolymer resin.

[0075] The first polymer resin may be PEBAX® 25R53, PEBAX® 35R53, PEBAX® 40R53, PEBAX® 55R53, PEBAX® 72R53, PEBAX® Clear1200, Rilsan® BESNO or equivalent products from Arkema France.

[0076] The second polymer resin comprises one selected from the group consisting of hydroxyl groups, acetyl groups, and combinations thereof in the branch.

[0077] Specifically, the second polymer resin may be a polyvinyl alcohol resin or a polyvinyl acetal resin. The polyvinyl acetal resin can be obtained by synthesizing polyvinyl alcohol and an aldehyde.

[0078] The above second polymer resin may have a degree of polymerization of 3,500 or less.

[0079] The second polymer resin above can be applied to the formation of a coating film, etc. when the polymerization degree is low, and to the production of a film by extrusion, etc. when the polymerization degree is above a certain level.

[0080] In the implementation example, the first polymer resin and the second polymer resin are mixed and applied, and both grades can be applied.

[0081] For example, the second polymer resin may be a polyvinyl alcohol resin having a degree of polymerization of 200 to 3,500. Alternatively, the second polymer resin may be a polyvinyl acetal resin obtained by acetalizing a polyvinyl alcohol resin having a degree of polymerization of 200 to 3,500 with an aldehyde.

[0082] For example, the second polymer resin may be a polyvinyl alcohol resin having a degree of polymerization of 1,600 to 3,000. Alternatively, the second polymer resin may be a polyvinyl acetal resin obtained by acetalizing a polyvinyl alcohol resin having a degree of polymerization of 1,600 to 3,000 with an aldehyde.

[0083] For example, the second polymer resin may be a polyvinyl alcohol resin having a degree of polymerization of 1,700 to 2,500. Alternatively, the second polymer resin may be a polyvinyl acetal resin obtained by acetalizing a polyvinyl alcohol resin having a degree of polymerization of 1,700 to 2,500 with an aldehyde.

[0084] When applied to such a second polymer resin, the mechanical properties of the film can be sufficiently improved.

[0085] The above aldehyde may be any one selected from the group consisting of n-butyl aldehyde, isobutyl aldehyde, n-barrel aldehyde, 2-ethyl butyl aldehyde, n-hexyl aldehyde, and blend resins thereof. When n-butyl aldehyde is used as the above aldehyde, the produced polyvinyl butyral resin may have excellent optical characteristics.

[0086] The above second polymer resin contains a hydroxyl group.

[0087] The hydroxyl group content of the second polymer resin may be 2 wt% or more, 5 wt% or more, 8 wt% or more, 10 wt% or more, 15 wt% or more, 16 wt% or more, or 19 wt% or more. In addition, the hydroxyl group content of the second polymer resin may be 60 wt%, 50 wt%, 40 wt%, or 30 wt% or less.

[0088] The second polymer resin may have an acetyl group content of 0.01 wt% or more, 1.5 wt% or more, 3 wt% or more, 5 wt% or more, or 10 wt% or more. In addition, the second polymer resin may have an acetyl group content of 20 wt% or less, 15 wt% or less, or 12 wt% or less.

[0089] When applied as a second polymer resin with these characteristics, compatibility with the plasticizer described below can be enhanced, and the deterioration of the film's optical performance due to haze changes can be effectively suppressed. This is thought to be because the hydroxyl groups, etc. located in the branched portions inhibit the migration of unreacted polyether monomers (or oligomers), thereby helping to suppress haze changes.

[0090] In addition, when applied as a second polymer resin having these characteristics, flexibility and elasticity can be imparted to the first polymer resin, effectively suppressing the decrease in tensile recovery rate of the film due to stretching.

[0091] The above film may further include a plasticizer. The plasticizer may be included in an amount of 0.5 parts by weight or less based on 1 part by weight of the second polymer resin.

[0092] The plasticizer may be included in an amount of 0.01 parts by weight or more, 0.05 parts by weight or more, 0.08 parts by weight or more, 0.1 parts by weight or more, 0.12 parts by weight or more, or 0.15 parts by weight or more, based on 1 part by weight of the second polymer resin. In addition, the plasticizer may be included in an amount of 0.5 parts by weight or less, 0.4 parts by weight or less, 0.35 parts by weight or less, or 0.3 parts by weight or less, based on 1 part by weight of the second polymer resin.

[0093] The above film contains a plasticizer in the following amount based on 100 parts by weight of a base resin composed of a first polymer resin and a second polymer resin.

[0094]

[0095] Based on 100 parts by weight of the base resin, the plasticizer may be included in an amount of 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. In addition, based on 100 parts by weight of the base resin, the plasticizer may be included in an amount of 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.

[0096] Specifically, the plasticizer may be any one selected from the group consisting of triethylene glycol bis-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), bis-2-hexyl adipate (DHA), and combinations thereof. Specifically, the plasticizer may include any one selected from the group consisting of triethylene glycol di-2-ethyl butyrate, triethylene glycol di-2-ethylhexanoate, triethylene glycol di-n-heptanoate, and combinations thereof. More specifically, triethylene glycol bis-2-ethylhexanoate (3G8) may be applied as the plasticizer. These plasticizers have excellent miscibility with the second polymer resin and can simultaneously improve workability and optical performance.

[0097] To achieve the above purpose, a film according to one embodiment of the embodiment includes a first polymer resin and a second polymer resin, which are heterogeneous resins. Since a specific description of the first polymer resin and the second polymer resin overlaps with that provided above, a detailed description thereof is omitted.

[0098] The film may contain 2.5 parts by weight or less of the second polymer resin based on 1 part by weight of the first polymer resin. Specifically, the film may contain 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 of the second polymer resin based on 1 part by weight of the first polymer resin. The film may contain 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 of the second polymer resin based on 1 part by weight of the first polymer resin.

[0099] When the film is manufactured at this ratio, migration of unreacted polyether monomers (including oligomers) can be minimized. Furthermore, it can effectively suppress the deterioration of the film's optical performance due to haze changes. Furthermore, when the film is manufactured at this ratio, the deterioration of the film's tensile recovery rate due to stretching can be effectively suppressed.

[0100] The thickness of the above film may be 1,000 μm or less. Specifically, the thickness of the above film may be 500 μm or less, 250 μm or less, or 150 μm or less. The thickness of the above film may 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 may be 100 μm or more. When the above film is manufactured with such a thickness, a film that is thin and light, yet has excellent impact resistance and other properties, and has low haze can be provided.

[0101]

[0102] Film properties

[0103] A film according to one or more embodiments may have a tensile recovery of at least 90% at 60% elongation.

[0104] The tensile recovery at N% elongation of the film can be derived according to Equation 1 below.

[0105] [Formula 1]

[0106] Tensile recovery rate (%) = (LfN - LiN) / (LfN - Li)

[0107] In the above equation 1, LfN is the length of the film stretched at an elongation of N %, LiN is the length to which the stretched film has recovered, and i is the length of the film before stretching.

[0108] The above elongation is the percentage (%) of the elongated length obtained by applying tension to the film in one direction divided by the length of the film in one direction before applying tension.

[0109] As an example, a method for measuring tensile recovery is described. A film sample of 60 mm to 100 mm in length is prepared, 50 mm of the length is marked, and tension is applied and stretched by applying the constant elongation mentioned above. That is, tension is applied and stretched so that the film sample has a length of LfN and maintained for 10 seconds. The tension applied to the stretched film is then removed and allowed to stand at room temperature for 5 minutes. The marked length of the film after standing is measured and taken as the recovered length of the stretched film, LiN.

[0110] When the above N % is 20 %, the tensile recovery rate of the film may be 90% or more, 95% or more, 96% or more, or 97% or more. The tensile recovery rate may be 100% or less or 99% or less.

[0111] When the above N % is 40 %, the tensile recovery rate of the film may be 85% or more, 90% or more, or 95% or more. The tensile recovery rate may be 100% or less or 99% or less.

[0112] When the above N % is 60 %, the tensile recovery rate of the film may be 80% or more, 85% or more, 90% or more, or 93% or more. The tensile recovery rate may be 100% or less or 99% or less.

[0113] When the above N % is 80 %, the tensile recovery rate of the film may be 75% or more, 80% or more, 85% or more, or 90% or more. The tensile recovery rate may be 100% or less or 99% or less.

[0114] When the above N % is 100%, the tensile recovery rate of the film may be 75% or more, 80% or more, 82% or more, or 84% or more. The tensile recovery rate may be 100% or less or 99% or less.

[0115] When the film has such a tensile recovery rate, the degree of plastic deformation occurring in the film can be minimized even when performing operations such as stretching and attaching the film. In addition, the formation of spaces such as air bubbles between the attachment target and the film can be substantially suppressed.

[0116] The tensile recovery reduction factor (20-40) between the above 20% elongation and the above 40% elongation can be derived according to Equation 2 below. There is no unit.

[0117] [Formula 2]

[0118] Tensile recovery rate reduction factor (20-40) =

[0119] In Equation 2, A 20 is the tensile recovery rate (%) of the film at 20% elongation, and A 40 is the tensile recovery rate (%) of the above film at 40% elongation.

[0120] The tensile recovery rate reduction factor (20-40) of the above film may be 0.3 or less, 0.2 or less, or 0.1 or less. The tensile recovery rate reduction factor (20-40) may be 0.01 or more.

[0121] The tensile recovery reduction factor (40-60) between the above 40% elongation and the above 60% elongation can be derived according to Equation 3 below. There is no unit.

[0122] [Formula 3]

[0123] Tensile recovery rate reduction factor (40-60) =

[0124] In Equation 3, A 40 is the tensile recovery rate (%) of the film at 40% elongation, and A 60 is the tensile recovery rate (%) of the above film at 60% elongation.

[0125] The tensile recovery rate reduction factor (40-60) of the above film may be 0.3 or less, 0.2 or less, or 0.1 or less. The tensile recovery rate reduction factor (40-60) may be 0.01 or more.

[0126] To be advantageous for application as a surface protection film, the film should have high strength and be easy to construct.

[0127] The strength of a film is related to its ability to protect the surface of an object from external impacts (e.g., stones, door dings, etc.). This is related to the film stress at high strains in the stress-strain curve.

[0128] In order to smoothly attach a film to the surface of an object, including curved and folded surfaces, it is preferred that the film be easily deformed in the small strain range where construction properties are applied. This is related to the film stress at small strains in the stress-strain curve.

[0129] In a stress-strain curve, the low strain region refers to a strain region of about 100% or less or about 80% or less.

[0130] In a stress-strain curve, the high strain region refers to a strain region of about 200% to about 400%.

[0131] The above film has a stress of 7 N / mm when the strain is 20%.2 Below, 6.5 N / mm 2 Below, 6 N / mm 2 Below, 5.5 N / mm 2 or less, or 5 N / mm 2 It may be less than 1 N / mm. The above stress is 2 It could be strange.

[0132] The above film has a stress of 8 N / mm when the strain is 50%. 2 Below, 7.5 N / mm 2 or less, or 7 N / mm 2 It may be less than 2 N / mm. The above stress is 2 It could be strange.

[0133] The above film has a stress of 6 N / mm when the strain is 300%. 2 Above, 7 N / mm 2 Above, 8 N / mm 2 Above, 9 N / mm 2 or 10 N / mm 2 It may be above 20 N / mm 2 It could be as follows:

[0134] The value obtained by subtracting the stress when the strain is 20% from the stress when the strain is 100% is 5 N / mm 2 It may be less than 5 N / mm. The above-mentioned subtracted value is 5 N / mm 2 Below, 4 N / mm 2 Below, 3.4 N / mm 2 Below, 3 N / mm 2 or less, or 2.5 N / mm 2 It may be less than 1.2 N / mm. The above-mentioned value is 1.2 N / mm. 2 This may be ideal. This means that the stress change is relatively small in the low strain range, and films with these characteristics may have excellent workability when applied as protective films for coatings, etc.

[0135] The ratio of stress at 20% strain to stress at 100% strain may be 0.45 or greater. The ratio may be 0.45 or greater, 0.5 or greater, or 0.55 or greater. The ratio may be 0.85 or less, or 0.8 or less. This means that the film stress in the low strain range does not differ significantly from the stress at 100% strain, and a film having such characteristics may have excellent workability.

[0136] The ratio of stress at 300% strain to stress at 100% strain may be 1.4 or greater. The ratio may be 1.4 or greater, 1.45 or greater, or 1.5 or greater. The ratio may be 3 or less, or 2.2 or less. This means that the stress at 300% strain is considerably greater than the stress at 100% strain, and having these characteristics can provide a film with excellent strength.

[0137] Films with these stress values ​​exhibit excellent workability and strength, making them ideal for use as surface protection films. These films are believed to be the result of blending heterogeneous resins and applying plasticizers.

[0138] The film may have a haze value of 3% or less at room temperature. Specifically, the film may have a haze value of 2.5% or less, or 2% or less, at room temperature. The film may have a haze value of 0% or more, or 0.1% or more, at room temperature. Such a film may secure a level of transparency applicable as an optical film.

[0139] The film may have a haze value of 3% or less after being left at 60°C for 7 days. Specifically, the film may have a haze value of 2.5% or less, or 2% or less, after being left at 60°C for 7 days. The film may have a haze value of 0% or more, or 0.1% or more, after being left at 60°C for 7 days.

[0140] The film may have a haze value difference of 1% or less before and after being left at 60°C for 7 days. Specifically, the film may have a haze value difference of 0.5% or less, 0.3% or less, 0.1% or less, 0.05% or less, 0.01% or less, or 0.001% or less before and after being left at 60°C for 7 days. The film may have a haze value difference of 0% or more, or 0.0001% or more before and after being left at 60°C for 7 days.

[0141] In this case, the film can minimize the deterioration of optical performance by having a small change in haze value even when exposed to a film application work environment that is relatively higher than room temperature for a long period of time.

[0142]

[0143] Uses of film

[0144] The above film may be used as a surface protection film.

[0145] The surface protection film described above can be applied to automobiles, aircraft, electronic products, furniture, etc. (hereinafter referred to as "articles"). The articles may include a painted surface on which at least a portion of the surface is coated with paint or the like. The surface protection film can be attached to the painted surface and function to protect the article from peeling.

[0146] The above surface protection film can be placed on a substrate (object, painted surface). This can prevent the surface of the substrate from being exposed to the outside.

[0147] A coating may be formed on the surface of the above-mentioned substrate. The surface protection film may be disposed on the coating. This prevents the coating from being exposed to the outside, thereby preventing damage to the coating.

[0148] An adhesive layer may be added between the surface of the above-mentioned substrate and the surface protection film. The adhesive layer may be formed on one side of the surface protection film and attached to the surface of the above-mentioned substrate.

[0149]

[0150] Film manufacturing method

[0151] A method for manufacturing a film includes a preparatory step of preparing a mixture of a film composition including a first polymer resin and a second polymer resin; and a forming step of extruding the mixture and forming it into a sheet shape.

[0152] Specific descriptions of the first polymer resin and the second polymer resin overlap with those given above, so detailed descriptions are omitted.

[0153] The above film composition may further contain a plasticizer.

[0154] Specific descriptions, contents, etc. of the first polymer resin, second polymer resin, plasticizer, etc. included in the film composition overlap with the above description, so detailed descriptions are omitted.

[0155] The above mixture is a mixture of a first polymer resin and a second polymer resin.

[0156] The above mixture may be a mixture of a second polymer resin mixed with a plasticizer and a first polymer resin.

[0157] The second polymer resin may have sticky properties. When the second polymer resin mixed with a plasticizer is mixed with the first polymer resin, the miscibility of the composition can be further improved.

[0158] The composition may optionally further comprise a light absorber. The light absorber can mitigate deterioration of the optical properties and mechanical properties of the film due to exposure to ultraviolet rays.

[0159] The above light absorbent may include any one selected from the group consisting of benzotriazole compounds, oxanilide compounds, hydroxybenzophenone compounds, hydroxyphenyltrizine compounds, benzoic acid ester compounds, and combinations thereof. Such compounds may exhibit excellent compatibility with the polyether block amide copolymer resin, and may effectively absorb ultraviolet rays to stably prevent deterioration of the film.

[0160] 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, and Tinuvin 1577 can be applied as light absorbers.

[0161] The composition may contain 0.1 or more, 0.2 or more, 0.35 or more, or 0.5 or more parts by weight of the light absorber, based on 100 parts by weight of the total of the first polymer resin and the second polymer resin. The composition may contain 5 or less, 3 or less, or 2 or less parts by weight of the light absorber, based on 100 parts by weight of the total. In this case, the yellowing and curing speed of the manufactured film can be effectively slowed down.

[0162] The above film may further include additives commonly used in the film field. Examples of such additives include lubricants, anti-blocking agents, heat stabilizers, antistatic agents, and impact modifiers.

[0163] The forming step is a step of forming the composition into a sheet shape.

[0164] The above molding step may be, for example, a process in which the mixture is extruded in a molten state and molded into a sheet form through a T-die.

[0165] The above molding step can be, for example, performed by extruding the mixture in a molten state, placing it on a carrier film, passing it between rollers, and molding it into a sheet shape.

[0166] In the molding step, the temperature of the melt extrusion of the mixture can be applied at 150 to 300°C. The sheet molded through the melt extrusion process can be applied as the film described above.

[0167] The film of the embodiment may be an extruded film. Extruded films have the advantages of being relatively easy to mass-produce and of being capable of forming laminated films that include additional layers. When manufactured as an extruded film, film thickness control is relatively easy, and compared to casting manufacturing methods, it is advantageous in producing relatively thick films with well-controlled overall thickness. For example, the thickness of the extruded film may be 80 μm or greater, 90 μm or greater, or 100 μm or greater.

[0168] The film of the embodiment may further include a plasticizer. The plasticizer can control the modulus of the film. Specifically, a film including a plasticizer can lower the modulus, which can improve the workability of the surface protection film.

[0169]

[0170] Hereinafter, a more detailed explanation will be given through specific examples. The following examples are merely illustrative examples to aid understanding of the present invention and are not intended to limit the scope of the present invention.

[0171]

[0172] Manufacturing example: Manufacturing of film

[0173] A polyether block amide copolymer resin was applied as the first polymer resin. Specifically, PEBAX® 40R53 or PEBAX® 35R53 was applied. PEBAX® 40R53 is a polyether block amide resin commercially available from Arkema France containing about 46 wt% of PA11 residues and about 54 wt% of polytetramethylene glycol residues as amide residues, and is abbreviated as 40R53. PEBAX® 35R53 is a polyether block amide resin commercially available from Arkema France containing about 31 wt% of PA11 residues and about 69 wt% of polytetramethylene glycol residues as amide residues, and is abbreviated as 35R53.

[0174] A polyvinyl acetal resin composition was applied as the second polymer resin. Specifically, polyvinyl butyral resin (PVB), synthesized using a conventional synthesis process from polyvinyl alcohol and n-butyraldehyde with a polymerization degree of 1700 and a saponification degree of 99, was applied. The polyvinyl butyral resin contained 20.3 wt% of hydroxyl groups, 78.9 wt% of butyral groups, and 0.8 wt% of acetyl groups, and is abbreviated as PVB.

[0175] The plasticizer used is triethylene glycol bis-2-ethylhexanoate, abbreviated as 3G8.

[0176] The contents were applied as shown in Table 1 below, and the composition was mixed through an extruder to prepare a mixture. The mixture was melt-extruded through an extruder owned by SK Microworks to prepare a sheet, which was then applied as a film in the example.

[0177] In the comparative examples, a polyether block amide copolymer resin was applied alone and molded into a film (Comparative Example 1) or a commercially available TPU (Comparative Example 2) was applied. The TPU used was Argotec's 49510 product.

[0178] Content: Weight parts Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 First polymer resin (40R53) 707070---100 First polymer resin (35R53)---707070-Second polymer resin (PVB) 21.625.830 21.625.830-Plasticizer (3G8) 8.44.20 8.44.20-

[0179] Experimental Example: Evaluation of Physical Properties

[0180] Stress-strain curves were measured using an Instron universal materials testing machine. The results are shown in Table 2.

[0181] Stress (N / mm^2)Example 1Example 2Example 3Example 4Example 5Example 6Comparative Example 1Comparative Example 2Strain 10%3.03.44.21.61.61.85.13.1Strain 20%4.75.16.12.62.73.07.24.4Strain 50%6.56.98.04.04.14.58.47.2Strain 100%6.77.18.44.44.65.18.310.7Strain 200%7.78.710.34.95.36.29.217.0Strain 300%10.111.714.66.36.98.711.225.5Strain 100% minus 20% strain (N / mm^2)222.31.81.92.11.16.3Ratio of 20% strain based on 100% strain0.70.720.730.590.590.590.870.41Ratio of 300% strain based on 100% strain1.511.651.741.431.51.711.352.38

[0182] The elongation recovery rate was evaluated using the sample of Example 2.

[0183] Film samples measuring 60 mm to 100 mm in length were prepared, marked at 50 mm in length, and stretched by applying tension using the elongation ratios shown in Table 3. That is, the film sample was stretched by applying tension so that it had a length of LfN and held for 10 seconds. After that, the tension applied to the stretched film was removed and it was left at room temperature for 5 minutes. The marked length of the film after standing was measured and the length to which the stretched film recovered, LiN, was used. The elongation recovery ratio was calculated using Equation 1 below.

[0184] [Formula 1]

[0185] Tensile recovery rate (%) = (LfN - LiN) / (LfN - Li)

[0186] In the above equation 1, LfN is the length of the film stretched at an elongation of N %, LiN is the length to which the stretched film has recovered, and Li is the length of the film before stretching.

[0187] Length after elongation (mm)Elongation length (mm)Elongation (%)Length after recovery (mm)Recovery length (mm)Tensile recovery (%)Tensile recovery reduction factor (20-40)Tensile recovery reduction factor (40-60)Comparative example 160102050.59.5950.250.570204052189080306056248090408058328010050100643672Example 260102050.39.7970.10.085702040511995803060522893.390408054369010050100584284Comparative example 260102050101000.1250.0170204050.519.597.580306050.729.397.790408051.338.796.81005010051.648.496.8

[0188] Referring to Tables 1 to 3 above, when comparing the properties with TPU used as a surface protection film, it was confirmed that Examples 1, 2, 4, and 5 containing a plasticizer showed lower stress at low strains such as 10% and 20%, thereby improving workability.

[0189] In addition, referring to Examples 1 and 2 and Comparative Example 1, it was confirmed that the stress at high strain was similar to that of the first polymer resin alone, but the stress at low strain was reduced, thereby improving workability.

[0190] Referring to the results of Comparative Example 1 and Examples 1 to 6, it was confirmed that by mixing the second polymer resin, the stress is somewhat lowered in a low strain range while the stress is improved in a high strain range, thereby simultaneously improving workability and strength so that the first polymer resin and the second polymer resin can be used as a surface protection film.

[0191]

[0192] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. A film comprising a first polymer resin and a second polymer resin, which are heterogeneous resins; The above first polymer resin includes a polyamide repeating unit and a polyether repeating unit, The second polymer resin comprises one selected from the group consisting of hydroxyl groups, acetal groups, and combinations thereof in the branch, The tensile recovery at N % elongation is derived according to Equation 1 below, A film having a tensile recovery rate of 90% or more when the above N % is 60%; [Formula 1] Tensile recovery rate (%) = (LfN - LiN) / (LfN - Li) In the above equation 1, LfN is the length of the film stretched at an elongation of N%, LiN is the length when the above-mentioned stretched film is recovered, Li is the length of the film before stretching.

2. In paragraph 1, When the strain is 100%, the stress is 1 N / mm 2 Lee Ha-in, film.

3. In paragraph 1, A film having a haze value of 3% or less after being left at 60°C for 7 days.

4. In paragraph 1, A film having a tensile recovery rate of 75% or more when the above N % is 100%.

5. In paragraph 1, A film comprising the polyether repeating unit in an amount of 10 wt% or more based on the total amount of the first polymer resin and the second polymer resin.

6. In paragraph 1, The tensile recovery rate reduction factor (20-40) between the above 20% elongation and the above 40% elongation is derived according to Equation 2 below, A film having a tensile recovery rate reduction coefficient (20-40) of 0.3 or less; [Formula 2] Tensile recovery rate reduction factor (20-40) = In equation 2, A 20 is the tensile recovery rate (%) of the above film at 20% elongation, A 40 is the tensile recovery rate (%) of the above film at 40% elongation.

7. Polyether block amide copolymer resin; and polyvinyl acetal resin, and the stress is 7 N / mm when the strain is 20%. 2 Lee Ha-in, film.

8. In paragraph 7, The value obtained by subtracting the stress when the strain is 20% from the stress when the strain is 100% is 5 N / mm 2 Lee Ha-in, film.

9. In paragraph 7, A film having a ratio of stress at 300% strain to stress at 100% strain of 1.4 or more.

10. In paragraph 1 or paragraph 7, The above film is a film that protects the coating.

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