resin film

Abstract

This invention provides a resin film that does not easily discolor even after prolonged exposure to high temperatures and suppresses fogging. The resin film of this invention comprises a thermoplastic resin, a polyester plasticizer, a β-diketone having an aromatic ring, and an ultraviolet absorber. Preferably, the polyester plasticizer comprises an aliphatic ester compound or an alicyclic ester compound.

Description

Technical Field

[0001] This disclosure relates to a resin film. Background Technology

[0002] Traditionally, films are applied to the surface of the substrate for decoration and protection. For example, Patent Document 1 discloses a resin composition for printing films, wherein, relative to 100 parts by weight of a vinyl chloride-based resin, it contains: (A) at least one of a benzotriazole compound represented by general formula (I) and / or at least one of a salicylamide compound represented by general formula (II) in 0.001 to 1 part by weight; (B) a β-diketone compound in 0.001 to 1 part by weight; and (C) a phenolic antioxidant in 0.001 to 1 part by weight.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-219244 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] Resin films can sometimes discolor due to heating, and are required to be resistant to discoloration even at high temperatures. Furthermore, some components of the resin film may volatilize at high temperatures. For example, when the volatilized substances adhere to glass or similar materials, the cooled volatilized substances can cause the glass or similar materials to become blurry, which is sometimes known as fogging.

[0008] The present invention is made in view of the above-mentioned situation, and its purpose is to provide a resin film that is not easily discolored even when placed in a high-temperature environment for a long time and that suppresses the occurrence of fogging.

[0009] Technical means to solve the problem

[0010] (1) One embodiment of the present invention is a resin film comprising a thermoplastic resin, a polyester plasticizer, a β-diketone having an aromatic ring, and an ultraviolet absorber.

[0011] (2) In one embodiment of the present invention, a resin film is provided, wherein the polyester plasticizer comprises an aliphatic ester compound or an alicyclic ester compound based on the structure of (1).

[0012] (3) In one embodiment of the present invention, a resin film is provided, wherein the polyester plasticizer comprises an adipic acid polyester compound based on the structure of (1) or (2).

[0013] (4) In one embodiment of the present invention, a resin film is provided, wherein, based on any of the structures in (1) to (3), the average molecular weight of the polyester plasticizer is 500 or more and 4000 or less.

[0014] (5) In one embodiment of the present invention, a resin film is provided, wherein, based on any of the structures in (1) to (4), the average molecular weight of the polyester plasticizer is 1600 or more and 3000 or less.

[0015] (6) In one embodiment of the present invention, a resin film is provided, wherein the β-diketone having an aromatic ring comprises an alkyl group having 7 or more carbon atoms, based on any of the structures in (1) to (5).

[0016] (7) In one embodiment of the present invention, a resin film is provided, wherein the β-dione having an aromatic ring is stearylbenzoylmethane.

[0017] (8) One embodiment of the present invention is a resin film that, based on any of the structures in (1) to (7), further contains an epoxy compound.

[0018] (9) In one embodiment of the present invention, a resin film is provided, wherein the thermoplastic resin is polyvinyl chloride based on any of the structures in (1) to (8).

[0019] (10) In one embodiment of the present invention, a resin film is provided, based on any of the structures described in (1) to (9), wherein the weight reduction rate of the resin film after heating at 95°C for 24 hours is less than 1.5% relative to the weight of the resin film before heating.

[0020] (11) In one embodiment of the present invention, a resin film is provided, which is a decorative film for vehicle use, based on any of the structures in (1) to (10).

[0021] The effects of the invention

[0022] This invention provides a resin film that does not easily change color even when placed in a high-temperature environment for a long time, and also suppresses the occurrence of fogging. Detailed Implementation

[0023] The embodiments of the present invention will be described below. The present invention is not limited to the contents described in the following embodiments, and appropriate design changes can be made within the scope of satisfying the structure of the present invention.

[0024] The resin film of this embodiment comprises a thermoplastic resin, a polyester plasticizer, a β-diketone having an aromatic ring, and a UV absorber. The resin film of this embodiment exhibits heat resistance to discoloration (hereinafter also referred to as heat-resistant discoloration) and a low rate of weight loss due to heating. A low rate of weight loss due to heating means that the volatilization of the resin film components due to heating is suppressed, which can be said to suppress fogging. The inventors have discovered that by including a β-diketone having an aromatic ring and a UV absorber, discoloration under high-temperature conditions can be effectively suppressed. Furthermore, the inventors conducted various studies on the cause of the weight loss due to heating and found that the cause is the volatilization of the plasticizer contained in the resin film. They also found that by using a polyester plasticizer as the plasticizer, the weight loss of the resin film due to heating can be suppressed. In addition, fogging can also be evaluated according to the methods of DIN752901-A and B of the German Institute for Standardization (DIN).

[0025] Examples of thermoplastic resins include: polyvinyl chloride (PVC), polyethylene resins, polypropylene resins, and acrylonitrile-butadiene-styrene copolymers (ABS resin). Among these, PVC is preferred in terms of high transparency, good elongation, conformability to the surface shape of the adherend, and resistance to breakage. The PVC content is preferably 50% by mass or more, and more preferably 90% by mass or more, relative to the overall resin composition of the resin film.

[0026] Examples of polyvinyl chloride (PVC) include homopolymers of vinyl chloride, copolymers of vinyl chloride with other monomers that can be copolymerized with vinyl chloride, and copolymers of vinyl chloride. Examples of other monomers that can be copolymerized include: vinyl acetate, vinyl propionate, and other vinyl esters; olefins such as ethylene, propylene, and styrene; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, and methyl methacrylate; dibutyl maleate, diethyl maleate, and other diesters of maleate; dibutyl fumarate, diethyl fumarate, and other diesters of fumarate; acrylonitrile, methacrylonitrile, and other acrylonitrile; vinyl halogenated compounds such as vinylidene chloride and vinyl bromide; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, etc. These can be used alone or in combination of two or more. Furthermore, in this specification, "(meth)acrylic acid" means "at least one of acrylic acid and methacrylic acid".

[0027] The content of the other copolymerizable monomers in the copolymer is typically 50% by mass or less, preferably 10% by mass or less. In terms of excellent dimensional stability, the polyvinyl chloride is preferably a homopolymer of vinyl chloride.

[0028] The average degree of polymerization of the polyvinyl chloride (PVC) is preferably 800 to 1300. Furthermore, in this invention, the average degree of polymerization of PVC refers to the average degree of polymerization measured according to Japanese Industrial Standards (JIS) K 6721:1977 "Test Method for Vinyl Chloride Resins". If the average degree of polymerization exceeds 1300, the stretching of the PVC film may become insufficient. From the viewpoint of obtaining a PVC film with high transparency, the average degree of polymerization of PVC is more preferably 1100 or less.

[0029] The resin film of this embodiment contains a polyester-based plasticizer. Compared with phthalic acid-based plasticizers, polyester-based plasticizers have a higher molecular weight and are less prone to thermal decomposition. Therefore, they are less volatile at high temperatures than phthalic acid-based plasticizers, thus reducing the weight loss rate of the resin film and suppressing fogging. Furthermore, polyester-based plasticizers are superior to trimellitic acid-based plasticizers in terms of water absorption whitening properties and heat resistance.

[0030] As the polyester plasticizer, plasticizers comprising aliphatic ester compounds and alicyclic ester compounds are preferred. As the aliphatic ester compound (acyclic aliphatic ester), plasticizers comprising adipic acid-based polyester compounds, such as polyesters formed by the bonding of adipate esters, adipic acid, and polyols, are preferred. Specific examples of aliphatic ester compounds include Adekasizer (registered trademark) PN-7535, PN-7230, PN-7160, and PN-9302 manufactured by ADEKA Corporation, and Greensizer BZ-100 manufactured by Shin Nippon Rika Co., Ltd. As the alicyclic ester compound, cyclohexane-based carboxylic esters are preferred, for example. Specific examples of alicyclic ester compounds include HEXAMOLL (registered trademark) DINCH (HEXAMOLLDINCH) manufactured by BASF Corporation. Hexamol Dinch is a plasticizer containing di-isononyl-cyclohexane-dicarboxylic acid ester. These can be used alone or in combination of two or more. More preferably, the polyester-based plasticizer contains an aliphatic ester compound, which is less likely to cause water absorption and whitening.

[0031] If the number average molecular weight of the plasticizer is low, it can easily migrate to the adhesive layer when an adhesive layer is stacked on the resin film, sometimes leading to a decrease in adhesion during long-term storage of the resin film. From the viewpoint of suppressing resin film shrinkage, a higher number average molecular weight of the plasticizer is preferable, preferably 500 or more, more preferably 1000 or more, and even more preferably 2000 or more. The upper limit of the number average molecular weight of the plasticizer can be, for example, 4000. If the number average molecular weight of the plasticizer exceeds 4000, the PVC film will harden, making it difficult to conform to the shape of the substrate during molding.

[0032] The average molecular weight of the polyester plasticizer is preferably 500 or more and 4000 or less, more preferably 1600 or more and 3000 or less.

[0033] The number-average molecular weight (Mn) of the plasticizer was determined by gel permeation chromatography (GPC). Furthermore, the determination conditions are as follows.

[0034] Device Name: HLC-8120 (Manufactured by Tosoh Corporation)

[0035] Tubing string: 1 piece of G7000HXL 7.8 mm ID×30 cm; 2 pieces of GMHXL 7.8 mm ID×30 cm; 1 piece of G2500HXL 7.8 mm ID×30 cm (manufactured by Tosoh Corporation)

[0036] Sample concentration: diluted with tetrahydrofuran to a concentration of 1.5 mg / ml.

[0037] Mobile phase solvent: tetrahydrofuran

[0038] Flow rate: 1.0 ml / min

[0039] Column temperature: 40℃

[0040] The content of the plasticizer may be 5 parts by mass or more and 80 parts by mass or less relative to 100 parts by mass of the thermoplastic resin. If the content is less than 5 parts by mass, discoloration due to heating may easily occur, and the resin film may become too hard. If the content exceeds 80 parts by mass, fogging may occur. A more preferred lower limit for the content is 10 parts by mass, a more preferred upper limit is 60 parts by mass, a more preferred upper limit is 50 parts by mass, and a more preferred upper limit is 30 parts by mass. Furthermore, in this specification, when the thermoplastic resin is polyvinyl chloride, the "relative to 100 parts by mass of thermoplastic resin" used as the basis for the content of each component is replaced with "relative to 100 parts by mass of polyvinyl chloride".

[0041] The polyester-based plasticizer is preferably free of plasticizers containing benzene rings. Examples of plasticizers containing benzene rings include: di-2-ethylhexyl phthalate (dioctyl phthalate, DOP), dibutyl phthalate, dinonyl phthalate, diisononyl phthalate (DINP), bis(2-ethylhexyl) terephthalate (dioctyl terephthalate, DOTP), and other phthalic acid-based plasticizers, trimellitic acid-based plasticizers, etc. The content of the plasticizer containing benzene rings is preferably less than 5 parts by weight per 100 parts by weight of thermoplastic resin, and more preferably, it does not contain the plasticizer containing benzene rings.

[0042] The resin film of this embodiment contains the β-diketone having an aromatic ring. By including the β-diketone, discoloration due to heating can be suppressed. Without the β-diketone, the resin composition will color during melt mixing. Furthermore, a β-diketone is a compound having two ketone groups bonded via a single carbon atom, and the β-diketone having an aromatic ring refers to a substance in which at least one of the two ketone groups has an aromatic ring.

[0043] The β-diketone having an aromatic ring is preferably one of the compounds represented by the following chemical formula (1), wherein either R1 or R2 (R1 and R2 may be the same or different, representing hydrocarbon groups) has an aromatic ring. Furthermore, the β-diketone having an aromatic ring is more preferably one of the compounds represented by the following chemical formula (1), wherein the other of R1 and R2 is an alkyl group. By using a β-diketone having both an aromatic ring and an alkyl group, the heat resistance and colorfastness can be further improved compared to using a β-diketone without an alkyl group.

[0044] [Chemistry 1]

[0045]

[0046] The β-diketone having an aromatic ring is preferably as shown in the following chemical formula (2), wherein in the compound represented by chemical formula (1), either R1 or R2 is benzyl and the other is alkyl. That is, the β-diketone having an aromatic ring is preferably alkylbenzoylmethane. Compared with dibenzoylmethane in the compound represented by chemical formula (1), where both R1 and R2 are benzyl, the alkylbenzoylmethane can improve the heat resistance and colorfastness of the resin film.

[0047] [Chemistry 2]

[0048]

[0049] The β-diketone having an aromatic ring is preferably composed of an alkyl group having 7 or more carbon atoms. Because the β-diketone having an aromatic ring contains an alkyl group having 7 or more carbon atoms, it exhibits good compatibility with polyester plasticizers and can be uniformly dispersed when mixed in resin compositions. Therefore, it can more effectively suppress discoloration at high temperatures caused by localized material bias. More preferably, the alkyl group has 10 or more carbon atoms, and even more preferably 16 or more. An upper limit for the number of carbon atoms in the alkyl group is, for example, 25.

[0050] The β-diketone having an aromatic ring is more preferably stearoylbenzoylmethane represented by the following chemical formula (3) (R1 in the chemical formula (2) represents an alkyl group with 17 carbon atoms).

[0051] [Chemistry 3]

[0052]

[0053] The content of the β-diketone having an aromatic ring relative to 100 parts by weight of thermoplastic resin is preferably 0.01 parts by weight or more and 2.0 parts by weight or less, more preferably 0.1 parts by weight or more and 1.0 parts by weight or less, and even more preferably 0.4 parts by weight or more and 0.8 parts by weight or less.

[0054] The resin film contains an ultraviolet (UV) absorber. By containing the UV absorber, the resin film can suppress discoloration caused by heating. Furthermore, since the UV absorber has the function of inhibiting photodegradation of the resin components by absorbing UV light irradiating the surface of the resin film, it can also suppress discoloration caused by UV irradiation.

[0055] Examples of UV absorbers include benzotriazole-based, benzophenone-based, and triazine-based UV absorbers. Examples of benzotriazole-based UV absorbers include Adekastab LA-29, LA-24, LA-31RG, LA-32, and LA-36 manufactured by ADEKA Corporation. Examples of benzophenone-based UV absorbers include Adekastab 1413 manufactured by ADEKA Corporation. Examples of triazine-based UV absorbers include Adekastab LA-46 and LA-F70 manufactured by ADEKA Corporation, and Tinuvin 1600 manufactured by BASF Corporation. Especially since polyvinyl chloride (PVC) is particularly prone to photodegradation, these UV absorbers are preferably used when the resin film is a PVC film. These can be used individually or in combination of two or more.

[0056] The content of the ultraviolet absorber relative to 100 parts by weight of thermoplastic resin is preferably 0.5 parts by weight or more and 3.0 parts by weight or less. If the content is less than 0.5 parts by weight, it may not be able to sufficiently suppress heat-induced discoloration. If the content exceeds 3.0 parts by weight, the ultraviolet absorber may migrate to the surface of the resin film, which may cause bleedout. If bleedout occurs, the transparency of the resin film may sometimes decrease due to fogging. In addition, if an adhesive layer is laminated on the resin film, the adhesive properties of the adhesive layer may sometimes decrease. The content of the ultraviolet absorber is more preferably 1 part by weight or more, and more preferably 1.5 parts by weight or more.

[0057] The resin film may contain a hindered amine light stabilizer. A hindered amine light stabilizer is a compound whose structure contains a hindered amine, thereby inhibiting the degradation of the film by trapping free radicals generated by irradiation with ultraviolet light or other light. The hindered amine light stabilizer may be a compound with a hydrogen group, alkyl group, or alkoxy group bonded to the nitrogen atom of the piperidine ring. More preferably, the hindered amine light stabilizer is a compound with an alkoxy group bonded to the nitrogen atom of the piperidine ring. Examples of hindered amine light stabilizers include Adekastab LA-52, LA-81, LA-77Y, LA-63P, and LA-72 manufactured by ADEKA Corporation, and Tinuvin 123 manufactured by BASF Corporation.

[0058] The content of the hindered amine light stabilizer is, for example, 0.1 parts by mass and 2 parts by mass relative to 100 parts by mass of thermoplastic resin. If the content exceeds 2 parts by mass, exudation may occur. A more preferred lower limit for the content of the hindered amine light stabilizer is 0.2 parts by mass, and a more preferred upper limit is 1 part by mass.

[0059] The resin membrane preferably further comprises an epoxy compound. By incorporating an epoxy compound into the resin membrane, the processability of the resin membrane can be improved (inhibiting thermal degradation and decomposition under high-temperature conditions during membrane processing). Examples of such epoxy compounds include epoxidized soybean oil and epoxy-containing acrylic resins. Specific examples of epoxidized soybean oil include Adekasizer O-130P manufactured by ADEKA Corporation. Specific examples of epoxy-containing acrylic resins include Metacann (registered trademark) P-1901 manufactured by Mitsubishi Chemical Corporation and Marproof (registered trademark) G-0150M manufactured by Nippon Oil Company.

[0060] The content of the epoxy compound relative to 100 parts by weight of thermoplastic resin is preferably 0.5 parts by weight or more and 6 parts by weight or less, more preferably 1 part by weight or more and 4 parts by weight or less, and even more preferably 1 part by weight or more and 2 parts by weight or less.

[0061] The resin film may further contain stabilizers. Halogenated resins such as polyvinyl chloride are prone to thermal decomposition due to dehydrohalogenation during melt mixing or film forming; therefore, heat stabilizers are sometimes added to inhibit deterioration during processing. Additives that inhibit deterioration or decomposition of the resin composition during mixing or film formation are also called stabilizers, and additives that inhibit thermal decomposition are particularly called heat stabilizers. By inhibiting thermal decomposition during processing, discoloration can be suppressed.

[0062] Examples of heat stabilizers include phosphites, Ba-Zn heat stabilizers, hydrotalcite, and zinc stearate. These heat stabilizers can be used alone or in combination of two or more.

[0063] The resin film may contain antioxidants, anti-exudation agents, etc., as needed.

[0064] The content of the heat stabilizer relative to 100 parts by weight of thermoplastic resin is preferably 1 part by weight or more and 10 parts by weight or less, more preferably 2 parts by weight or more and 7 parts by weight or less, and even more preferably 3 parts by weight or more and 4 parts by weight or less.

[0065] The thickness of the resin film is, for example, 50 μm or more and 300 μm or less. If the thickness is less than 50 μm, the strength is insufficient, and sometimes adequate durability cannot be achieved. If the thickness exceeds 300 μm, the rigidity becomes too strong, and it may be difficult to adhere to the substrate. The preferred lower limit of the thickness is 60 μm, and the preferred upper limit is 160 μm.

[0066] The resin film in this embodiment preferably exhibits a weight reduction rate of 1.5% or less after heating at 95°C for 24 hours relative to its weight before heating. If the weight reduction rate exceeds 1.5%, there will be more volatiles at high temperatures, making atomization more likely. More preferably, the weight reduction rate is 1.2% or less, even more preferably 1.0% or less, and particularly preferably 0.8%.

[0067] Regarding the weight reduction rate of the resin film, specifically, test pieces were prepared by cutting the resin film into 10 cm long and 10 cm wide pieces, placing the test pieces in a constant temperature oven (air-cooled oven) set to 95°C (manufactured by Kusumoto Chemical Co., Ltd., ETAC HS260), and removing them after 24 hours. The weight reduction rate (%) was then calculated using the following formula.

[0068] Weight loss = Weight before heating (g) - Weight after heating (g)

[0069] Weight reduction rate (%) = (weight reduction / weight before heating) × 100

[0070] The resin film of this embodiment is a resin film that suppresses heat-induced discoloration. The discoloration ΔE of the resin film of this embodiment after heating at 95°C for 500 hours is preferably 4.5 or less, more preferably 3.0 or less, and even more preferably 1.5 or less. If the discoloration ΔE after heating at 95°C for 500 hours exceeds 4.5, it can be determined that the heat resistance to discoloration has significantly deteriorated.

[0071] The color change ΔE can be determined by the following method. First, the color change of the resin film before heating is measured at L... a b L in the color system a and b The L a and b A colorimeter (manufactured by Nippon Denshoku Kogyo Co., Ltd., SE6000) can be used. Subsequently, the resin film is placed in a constant temperature chamber (air-cooled oven) set to 95°C (manufactured by Kusumoto Kasei Co., Ltd., ETACHS260), and the L value is measured after 500 hours. a and b The heated L Subtract L before heating The obtained value is set as ΔL , will be heated from a Subtract a before heating Let the obtained value be Δa From the heated b Subtract b before heating Let the obtained value be Δb Through ΔL The square of Δa The square of and Δb Calculate ΔE by taking the square root of the sum of the squares of the given numbers (the following formula).

[0072] [Number 1]

[0073]

[0074] As a method for manufacturing resin films, examples include: mixing materials while heating (melt mixing) using a Banbury mixer or the like to obtain a resin composition, and then forming the resin composition into a film. Conventional forming methods such as calendering, extrusion molding, and injection molding can be used as the film-forming method, but calendering is preferred for producing films with excellent thickness accuracy even for thin films.

[0075] The laminated film formed by stacking the resin film of this embodiment with other layers is also an embodiment of the present invention. Examples of the other layers include adhesive layers, design layers, and primer layers.

[0076] The adhesive layer is not particularly limited as long as it has adhesive function (pressure-sensitive adhesion), and can include layers containing acrylic adhesives, rubber adhesives, silicone adhesives, etc. Among these, acrylic adhesives are preferred due to their superior transparency, adhesion, processability, heat aging resistance, weather resistance, and relatively low cost. The thickness of the adhesive layer is not particularly limited, but is preferably 10 μm to 60 μm, more preferably 20 μm to 50 μm.

[0077] When the adhesive layer is laminated on the resin film, the design layer may be disposed on the side of the resin film opposite to the adhesive layer side.

[0078] The design layer can be a printed layer, for example, through inkjet printing, gravure printing, screen printing, rotary screen printing, flexographic printing, offset printing, electrostatic printing, etc. Alternatively, a colored film can be laminated.

[0079] The laminated film can be adhered to an adhesive substrate for use. In this embodiment, the resin film is preferably a decorative film designed to adhere to the substrate. Examples of materials for the adhesive substrate include: polycarbonate resins, acrylic resins, styrene resins, acrylonitrile-butadiene-styrene copolymer (ABS resin); metals such as iron, copper, and aluminum; and alloys. Examples of the adhesive substrate include: decorative panels (wall decoration materials), interior doors, closet or kitchen doors, furniture, flooring, and interior materials for automobiles and other vehicles. Examples of interior materials for automobiles and other vehicles include dashboards and beverage holders. The interior of a car easily becomes hot and is a confined space in summer, making it prone to fogging. If fogging causes the car windows to become blurry, it will obstruct the user's vision and may hinder driving. The resin film of this embodiment has excellent heat resistance, colorfastness, and fogging resistance, and is therefore preferably used as a decorative film for automotive interiors in automobiles and other vehicles.

[0080] Example

[0081] The present invention will be described in more detail below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0082] Table 1 below shows the components other than β-diketones used in the following examples and comparative examples.

[0083] [Table 1]

[0084]

[0085] (Example 1)

[0086] Relative to 100 parts by weight of polyvinyl chloride, each component was added according to the formulations shown in Table 2 below to obtain a polyvinyl chloride-based resin composition. In Example 1, stearoylbenzoylmethane was used as a β-diketone. The obtained polyvinyl chloride-based resin composition was melt-kneaded at 180°C for 10 minutes using a biaxial roller, and then calendered into a sheet to produce the polyvinyl chloride film of Example 1.

[0087] (Examples 2-7, Comparative Example 1)

[0088] As shown in Table 2, except for changing the formulation of each component, the polyvinyl chloride films of Examples 2 to 7 and Comparative Example 1 were prepared in the same manner as in Example 1.

[0089] [Table 2]

[0090]

[0091] <Evaluation of heat resistance and color change>

[0092] For each embodiment and comparative example, three test pieces were prepared, each consisting of a 90 μm thick polyvinyl chloride (PVC) film cut into 10 cm × 10 cm pieces. The L value of each test piece was measured. a b L in the color system a and b A colorimeter (manufactured by Nippon Denshoku Kogyo Co., Ltd., SE6000) was used as the measuring device. For each embodiment and comparative example, the L value was measured using three test pieces. a and b The average value was used as the L before heating (0 hours) for each embodiment and comparative example. a and b .

[0093] Each test piece was placed in a constant temperature oven (air-cooled drying oven) set to 95°C (manufactured by Kusumoto Chemical Co., Ltd., ETAC HS260), and L was measured after 100 hours, 200 hours, 300 hours, 400 hours, and 500 hours. a and b For each embodiment and comparative example, L was measured using three test pieces. a and b The average value is used as L for each embodiment and comparative example at each elapsed time. a and b The L after a predetermined time will be used to represent each embodiment and comparative example. a and b (Average) minus L before heating (0 hours) a and The values ​​obtained by b (average) are respectively expressed by ΔL , Δa and Δb This indicates that, in addition, according to ΔL , Δa and Δb ΔE was calculated using the following formula. The results are shown in Tables 3 and 4 below. If ΔE is less than 1.5 after 500 hours, the heat resistance to discoloration is considered to be excellent. On the other hand, if ΔE exceeds 4.5, the heat resistance to discoloration is considered to be significantly worse.

[0094] [Number 2]

[0095]

[0096] [Table 3]

[0097]

[0098] [Table 4]

[0099]

[0100] <Determination of weight loss rate due to heating>

[0101] For each embodiment and comparative example, PVC film (90 μm thick) was cut into 10 cm × 10 cm test pieces, and the weight of each test piece (weight before heating) was measured. Each test piece was placed in a constant temperature oven (air-cooled oven) set to 95°C (manufactured by Kusumoto Chemical Co., Ltd., ETAC HS260), and removed after 24 hours, and the weight of each test piece (weight after heating) was measured. The weight reduction rate (%) of each embodiment and comparative example was calculated using the following formula, and the results are shown in Table 5 below.

[0102] Weight loss = Weight before heating (g) - Weight after heating (g)

[0103] Weight reduction rate (%) = (weight reduction / weight before heating) × 100

[0104] The smaller the weight reduction rate, the less volatile matter there is under high temperature conditions. If the weight reduction rate is below 1.5%, the worrying fogging in automotive decorative films can be reduced.

[0105] [Table 5]

[0106]

[0107] The formulations in Table 2, the results of ΔE after 500 hours, and the results of the weight loss due to heating are summarized in Table 6 below.

[0108] [Table 6]

[0109]

[0110] According to Table 6, in Examples 1-7 where polyester-based plasticizers were used as plasticizers, the weight loss rate after heating was low, and the volatilization of the plasticizers was suppressed. On the other hand, in Comparative Example 1 where phthalic acid-based plasticizers were used as plasticizers, the weight loss rate after heating exceeded 1.5%, which easily caused the plasticizers to volatilize.

Claims

1. A resin film comprising a thermoplastic resin, a polyester plasticizer, a β-diketone having an aromatic ring, and an ultraviolet absorber.

2. The resin film according to claim 1, wherein, The polyester plasticizer contains aliphatic ester compounds or alicyclic ester compounds.

3. The resin film according to claim 1 or 2, wherein, The polyester plasticizer includes adipic acid-based polyester compounds.

4. The resin film according to any one of claims 1 to 3, wherein, The average molecular weight of the polyester plasticizer is above 500 and below 4000.

5. The resin film according to any one of claims 1 to 4, wherein, The average molecular weight of the polyester plasticizer is above 1600 and below 3000.

6. The resin film according to any one of claims 1 to 5, wherein, The β-diketone having an aromatic ring comprises an alkyl group having 7 or more carbon atoms.

7. The resin film according to any one of claims 1 to 6, wherein, The β-dione with an aromatic ring is stearoylbenzoylmethane.

8. The resin film according to any one of claims 1 to 7 further comprises an epoxy compound.

9. The resin film according to any one of claims 1 to 8, wherein, The thermoplastic resin is polyvinyl chloride.

10. The resin film according to any one of claims 1 to 9, wherein, The weight reduction rate of the resin film after heating at 95°C for 24 hours was less than 1.5% compared to the weight of the resin film before heating.

11. The resin film according to any one of claims 1 to 10, wherein, The resin film is a decorative film for automotive applications.

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