TWI848175B - Laminated film and method for manufacturing the same - Google Patents

Abstract

The present invention provides a laminate film which has an excellent balance among initial adhesion to the surface of an optical sheet, suppression of adhesion enhancement, suppression of floating after heating, and suppression of contamination of an adherend. A laminate film having a resin layer (b) on one side of a substrate layer (a), wherein the resin layer (b) is a resin composition containing a hydrogenated copolymer composition and a tackifying resin, and the hydrogenated copolymer composition satisfies the following (1) to (3): (1) The hydrogenated copolymer composition is composed of a polymer block mainly composed of vinyl aromatic monomer units and a polymer block mainly composed of covalent diene monomer units, and the polymer block mainly composed of covalent diene monomer units is present at the end; (2) The content of vinyl aromatic monomer units in the hydrogenated copolymer composition as a whole is 5 to 30% by weight; (3) The melt flow rate of the hydrogenated copolymer composition is 3 to 30 g/10 minutes.

Description

Laminated film and method for manufacturing the same

The present invention relates to a laminated film and a method for manufacturing the same. The laminated film has an excellent balance among initial adhesion to the surface of an optical sheet, suppression of adhesion enhancement, suppression of floating after heating, and suppression of contamination of an adherend.

Products made of synthetic resins, metals, glass, and other materials are often treated by applying materials to protect the surface in order to prevent damage and contamination during processing, transportation, and storage. The representative material for protecting the surface is a protective film, which is generally a laminated film with an adhesive layer formed on a supporting substrate. The adhesive layer is attached to the adherend and covered with the supporting substrate to protect the surface. In addition, for such laminated films, the adhesion between the adhesive layer and the adherend is required to be of appropriate strength. The appropriate strength refers to the strength that does not fall off naturally or due to slight vibration or impact, and the strength that does not leave any adhesive layer on the surface of the adherend and can be peeled off smoothly.

In recent years, liquid crystal displays and touch panel displays have become increasingly popular, and they are made of a number of optical sheets containing synthetic resins. Since the optical sheets need to minimize defects such as light distortion, protective films are often used to prevent damage and contamination that may cause defects.

The properties required of a protective film include: it should not be easily peeled off from the adherend due to environmental changes such as temperature and humidity or the degree of slight stress; it should not have an increase in adhesion due to external factors such as time and temperature that increases the contact area between the adherend and the adhesive layer, which is the so-called adhesion enhancement; the adhesive and adhesive components should not remain on the adherend when peeled off, etc.

Among the optical sheets mentioned above, there are components with uneven surfaces such as diffusion plates, prism sheets, and diffusion surfaces with various shapes formed on the back of prism sheets. Immediately after the protective film is attached, the adhesive layer does not follow the uneven parts well, and the desired adhesive force cannot be obtained, resulting in peeling. For such issues, there are known methods of softening the adhesive layer and using a tackifier to increase the adhesive force.

Patent document 1 describes an adhesive resin composition and a protective film using the same. However, this protective film will partially peel off (or float up) if heated after being attached to an adherend, so it is necessary to contain a large amount of tackifier. If the adhesive layer contains a large amount of tackifier, the adhesive layer will easily remain on the surface of the adherend when the adhesive film is peeled off, resulting in the problem of contamination of the adherend by the adhesive layer.

Patent document 2 describes an adhesive composition and a surface protection film characterized by containing a copolymer or its hydrogenated product (hereinafter, hydrogenation is referred to as hydrogenation), a fatty acid amide with an acid value of 1 to 7. However, since the adhesive composition partially peels off when heated after being attached to an adherend, and the fatty acid amide overflows (the additive used in the film manufacturing floats on the film surface over time), there is a problem of contamination of the process, the manufactured surface protection film, and even the adherend to which the adhesive is attached. [Prior art document] [Patent document]

Patent document 1: International Publication No. 2019/044637 Patent document 2: Japanese Patent Publication No. 2012-1630

[Problems to be solved by the invention]

The subject of the present invention is to solve the above-mentioned problems. That is, to provide a laminated film that has an excellent balance in terms of initial adhesion to the surface of an optical sheet, suppression of adhesion enhancement, suppression of floating after heating, and suppression of contamination of the adherend. [Means for solving the subject]

The above problems can be solved by the following invention.

A laminate film having a resin layer (b) on one side of a substrate layer (a), wherein the resin layer (b) is a resin composition containing a hydrogenated copolymer composition and a tackifying resin, and the hydrogenated copolymer composition satisfies the following (1) to (3): (1) The hydrogenated copolymer composition is composed of a polymer block mainly composed of a vinyl aromatic monomer unit and a polymer block mainly composed of a covalent diene monomer unit, and the polymer block mainly composed of a covalent diene monomer unit is present at the end; (2) The content of the vinyl aromatic monomer unit in the hydrogenated copolymer composition as a whole is 5 to 30% by weight; (3) The melt flow rate of the hydrogenated copolymer composition is 3 to 30 g/10 minutes. In addition, a method for manufacturing a laminated film is the above-mentioned method for manufacturing a laminated film, wherein the substrate layer (a) and the resin layer (b) are formed by melt co-extrusion. [Effect of the invention]

The present invention can provide a laminate film having an excellent balance among initial adhesion to the surface of an optical sheet, suppression of adhesion enhancement, suppression of floating after heating, and suppression of contamination of an adherend.

[Form used to implement the invention]

In the present invention, the naming of each monomer unit constituting the copolymer is based on the naming of the monomer from which the monomer unit is derived. For example, the so-called "vinyl aromatic monomer unit" means a constituent unit of a polymer produced by polymerizing a vinyl aromatic compound as a monomer. The vinyl aromatic monomer unit is bonded to other monomer units by the vinyl group of the vinyl aromatic compound.

The so-called "conjugated diene monomer unit" refers to a constituent unit of a polymer produced as a result of polymerizing a conjugated diene compound as a monomer. The conjugated diene monomer unit is bonded to another monomer unit via one of the two double bonds of the conjugated diene compound (1,2-bonding or 3,4-bonding), or is bonded to another monomer unit via two double bonds of the conjugated diene compound (1,4-bonding).

The "vinyl aromatic compound" constituting the "vinyl aromatic monomer unit" is not limited to those shown below, but examples thereof include styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene. Among them, α-methylstyrene and p-methylstyrene are more preferred from the viewpoint of availability and productivity. Among them, styrene is particularly preferred. These may be used alone or in combination of two or more.

The "conjugated diene compound" constituting the "conjugated diene monomer unit" is a diene having a pair of conjugated double bonds. The conjugated diene compound is not limited to those described below, but for example, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, and bacteriochloride can be listed. As preferred dienes, 1,3-butadiene and isoprene can be listed. These can be used alone or in combination of two or more.

It is preferred to use a coupling agent in the hydrogenated copolymer composition, but the coupling agent is a multifunctional compound that allows the linear vinyl aromatic copolymer to be bonded in a radial manner. The coupling agent is not particularly limited, but examples thereof include polyene coupling agents. Examples of preferred polyene coupling agents include divinylbenzene, preferably o-divinylbenzene. In addition, as coupling agents, there can be cited tetraalkoxysilanes such as tetraethoxysilane and tetramethoxysilane, alkyltrialkoxysilanes such as methyltrimethoxysilane, dialkyldialkoxysilanes such as dimethyldimethoxysilane, carboxylic acid ester compounds such as ethyl benzoate and methyl benzoate, and diglycidyl aromatic epoxy compounds such as diglycidyl ether derived from the reaction of bisphenol A and epichlorohydrin.

The hydrogenated copolymer composition of the present invention comprises a polymer block mainly composed of vinyl aromatic monomer units and a polymer block mainly composed of covalent diene monomer units, and the polymer block mainly composed of covalent diene monomer units is present at the end. That is, when the polymer block mainly composed of vinyl aromatic monomer units is regarded as A and the polymer block mainly composed of covalent diene monomer units is regarded as B, it has a structural formula of B-A-B. Furthermore, it has a structural formula of B-A-B-X and a structural formula of (B-A-B)nX (n=2~4) in which the block structural bonds of (B-A-B) are radially bonded by the above-mentioned coupling agent. Here, X is a residual group of the coupling agent used. By arranging a polymer block mainly composed of a conjugated diene monomer unit at the end, floating after heating can be suppressed.

The content of the vinyl aromatic monomer units in the hydrogenated copolymer composition of the present invention is 5 to 30% by weight, preferably 6 to 20% by weight, and more preferably 8 to 12% by weight, based on the composition. If the content of the vinyl aromatic monomer units exceeds 30% by weight, the initial adhesion is reduced, and if the content of the vinyl aromatic monomer units is less than 5% by weight, the adhesion enhancement is deteriorated or the contamination is deteriorated.

The content of the vinyl aromatic monomer units in the hydrogenated copolymer composition of the present invention can be measured by an ultraviolet spectrophotometer as described in the examples below. In addition, the content of the vinyl aromatic monomer units is almost the same before and after hydrogenation, so it can be determined by the content of the vinyl aromatic monomer units in the copolymer before hydrogenation.

The ratio of double bonds of the covalent diene monomer units contained in the hydrogenated copolymer composition of the present invention (hereinafter referred to as the hydrogenation rate) is preferably 81 mol% or more, more preferably 85 mol% or more, and further preferably 90 mol%. If it is less than 81 mol%, the adhesion enhancement will be greater, or paste residue will be generated on the adherend.

The hydrogenation rate can be controlled by, for example, adjusting the amount of catalyst and the amount of hydrogen added during hydrogenation. In addition, the hydrogenation rate can be controlled by, for example, adjusting the amount of catalyst and the amount of hydrogen added during hydrogenation, the pressure and the temperature. Furthermore, the hydrogenation rate can be measured by the method described in the embodiments described below.

The melt flow rate (hereinafter referred to as "MFR" according to ISO 1133) of the hydrogenated copolymer composition of the present invention is 3 to 30 g/10 minutes, preferably 5 to 20 g/10 minutes, and further preferably 6 to 16 g/10 minutes at a temperature of 230°C and a load of 21.17 N (2.16 kgf). If the MFR exceeds 30 g/10 minutes, the initial adhesion becomes stronger, and the adhesion is greatly enhanced, and paste residues will also be produced. If the MFR is less than 3 g/10 minutes, floating after heating will occur. The MFR of the hydrogenated copolymer composition can be controlled by adjusting the polymerization conditions such as the amount of monomer added, polymerization time, temperature, polymerization initiator, etc., and can be measured according to the method described in the embodiments described below.

The resin layer (b) of the present invention contains a tackifying resin for the purpose of improving the initial adhesion. The resin is not particularly limited as long as it can impart viscosity to the laminated film of the present invention. For example, it is preferably at least one resin selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, aliphatic/aromatic petroleum resins, alicyclic petroleum resins, terpene resins, terpene phenol resins, rosin resins, alkylphenol resins and xylene resins. In addition, hydrides obtained by hydrogenating the unsaturated bonds of these resins can also be used. More preferred are aliphatic petroleum resins, aromatic petroleum resins, aliphatic/aromatic petroleum resins, alicyclic petroleum resins, terpene resins, and terpene phenol resins, and most preferred are aromatic petroleum resins and terpene phenol resins.

The tackifying resin may be used alone or in combination of two or more. The content of the tackifying resin in the resin composition of the resin layer (b) of the present invention is preferably 3 to 30% by weight, more preferably 5 to 20% by weight. When the tackifying resin content is less than 3% by weight, the desired initial adhesion cannot be obtained, and when it exceeds 30% by weight, the adhesion enhancement becomes greater, resulting in paste residue on the adherend.

The resin composition of the resin layer (b) of the present invention may further contain a hydrogenated styrene-based elastomer having a structure other than the above-mentioned specific hydrogenated copolymer composition of the present invention, with an upper limit of 50% by weight relative to the resin composition of the resin layer (b).

The hydrogenated styrene elastomer is not limited to the following, but styrene-copolymers such as styrene-butadiene copolymers (SBR), styrene-isoprene-styrene copolymers (SIS), styrene-butadiene-styrene copolymers (SBS), and hydrogenated products thereof (e.g., hydrogenated styrene-butadiene copolymers (HSBR) and styrene-ethylene-butylene-styrene copolymers (SEBS)), and styrene-isobutylene copolymers (e.g., styrene-isobutylene-styrene triblock copolymers (SIBS) and styrene-isobutylene diblock copolymers (SIB) or mixtures thereof) can be cited as representative hydrogenated styrene elastomers.

The resin composition of the resin layer (b) of the present invention may also contain stabilizers such as antioxidants and light stabilizers. In addition to the above-mentioned materials, various additives may also be added as needed.

The additive is not limited to the following, but includes, for example, pigments such as hematite and titanium dioxide, waxes such as wax, microcrystalline protein, low molecular weight polyethylene wax, amorphous polyolefin, polyolefin such as ethylene-ethyl acrylate copolymer, or low molecular weight vinyl aromatic thermoplastic resin, natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, ethylene-propylene rubber, chloroprene rubber, acrylic rubber, isoprene-isobutylene rubber, polypentamer rubber, and other synthetic rubbers.

Specific examples of the synthetic rubber include those described in "Rubber-Plastic Compounding Products" (edited by Rubber Digest Co., Ltd.) and the like.

The resin layer (b) of the present invention is formed on the base layer (a) by being laminated as a resin composition comprising the specific hydrogenated copolymer composition of the present invention and a tackifying resin.

The thickness of the resin layer (b) of the present invention is preferably 1 μm to 30 μm, more preferably 2 μm to 20 μm. If the thickness of the resin layer (b) exceeds 30 μm, productivity will be unstable, and if it is less than 1 μm, the adhesion to the adherend may deteriorate.

The material of the substrate layer (a) of the present invention is not particularly limited, and any non-polar resin or polar resin can be used. From the viewpoint of performance and price, the non-polar resin is preferably a polyolefin resin. The polyolefin resin contained in the substrate is not particularly limited, but polyethylene resins such as ethylene homopolymers, ethylene-α-olefin copolymers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylate copolymers, and ethylene-vinyl acetate copolymers, polypropylene resins such as propylene homopolymers, propylene-α-olefin copolymers, and propylene-ethylene copolymers, butene homopolymers, and homopolymers or copolymers of co-dienes such as butadiene and isoprene can be listed. Furthermore, as the above-mentioned polyethylene resin, high-density polyethylene, medium-density polyethylene or low-density polyethylene can be exemplified. The copolymerization form can be random, block, or a tertiary copolymer. The above-mentioned polyolefin resin can be used alone or in combination of two or more. The above-mentioned polyethylene resin can be obtained using ethylene as a main component. In 100% by weight of the total structural units of the above-mentioned polyethylene resin, the proportion of structural units derived from ethylene is preferably 50% by weight or more, more preferably 70% by weight or more, and further preferably 90% by weight or more. The above-mentioned polypropylene resin can be obtained using propylene as a main component. The proportion of structural units derived from propylene in the total structural units of the polypropylene resin is preferably 50% by weight or more, more preferably 70% by weight or more, and further preferably 90% by weight or more. The substrate layer (a) of the present invention is preferably mainly composed of a polypropylene resin from the viewpoint of heat resistance, weather resistance, or adhesion with the resin layer (b).

The thickness of the substrate layer (a) of the present invention is preferably 10 μm to 150 μm, more preferably 15 μm to 80 μm, and most preferably 20 μm to 50 μm.

In the case where the laminated film of the present invention only includes the substrate layer (a) and the resin layer (b), in order to suppress the adhesion between the surface of the substrate layer (a) and the surface of the resin layer (b), it is preferred to give the surface of the substrate layer (a) with irregularities so as to reduce the contact area with the resin layer (b). As such means, a resin that is incompatible with the resin used for the substrate layer (a) may be added, or organic or inorganic particles may be mixed.

When the base layer (a) is mainly composed of polypropylene, as the incompatible resin, an α-olefin polymer having 4 or more carbon atoms such as 4-methylpentene-1-series polymers can be used. Other examples include low-density polyethylene, high-density polyethylene, copolymers of ethylene and a small amount of α-olefin, copolymers of ethylene and vinyl acetate, polystyrene, alicyclic olefin resins, polyester resins, and polyamide resins.

Examples of the organic particles include polyethylene, polystyrene, and polymethyl methacrylate. Examples of polyethylene particles include high molecular weight polyethylene microparticles "mipelon" manufactured by Mitsui Chemicals Co., Ltd. and cross-linked acrylic acid monodisperse particles MX-1500H manufactured by Soken Chemical Co., Ltd. In addition, examples of inorganic particles include silicon dioxide and titanium oxide.

On the other hand, by adding a silicone-based release agent to the substrate layer (a), the adhesion to the surface of the resin layer (b) can be appropriately suppressed. Examples of the silicone-based release agent include "exfore" manufactured by Mitsui Chemicals Fine Chemicals Co., Ltd., BY27-201C and BY27-202H manufactured by Doyle-Toray Co., Ltd., and ParenY19220 and SiPP MB01 manufactured by Momentive Performance Materials Inc.

In the present invention, since the adhesion between the resin layer (b) and the second resin layer (c) can be suppressed, it is preferred that the second resin layer (c) is laminated on the other surface of the base layer (a).

The material constituting the second resin layer (c) of the present invention is not particularly limited, and is preferably the same composition as that of the substrate layer (a). From the viewpoint of productivity, cost, and release effect, it is preferred to add an incompatible resin, organic or inorganic particles, a release agent, etc. to the second resin layer (c).

The thickness of the second resin layer (c) of the present invention is preferably 1 μm to 20 μm. If the thickness of the second resin layer (c) is less than 1 μm, the processability during film formation is poor, and if it exceeds 20 μm, the cost of the laminated film is likely to increase.

Next, the manufacturing method of the laminated film of the present invention is described.

The method for producing the laminated film of the present invention is not particularly limited, but examples thereof include: in the case of a three-layer laminated structure of a resin layer (b), a substrate layer (a), and a second resin layer (c), the resin composition constituting each layer is melt-extruded from a separate extruder and integrated in a mold, which is called a co-extrusion method; after the resin layer (b), the substrate layer (a), and the second resin layer (c) are melt-extruded separately, a method of laminating them by a lamination method, etc. From the perspective of productivity, it is preferred to produce by the co-extrusion method. The materials constituting each layer may be mixed individually by a Henschel mixer or the like, or all or part of the materials of each layer may be kneaded in advance. As for the co-extrusion method, known methods such as blow molding and T-die method may be used, but from the viewpoint of excellent thickness accuracy and surface shape control, hot melt co-extrusion using T-die method is particularly preferred.

The laminated film of the present invention can be used as a surface protection film for preventing scratches and contaminants from adhering during the manufacturing, processing, and transportation of synthetic resin plates, metal plates, glass plates, etc., but it can be preferably used as an optical surface protection film having uneven surfaces such as diffusion plates and prism sheets. [Example]

The present invention is described in detail below by way of specific examples and comparative examples, but the present invention is not limited to the following examples. The physical property measurement methods and evaluation methods used in the examples and comparative examples are as follows.

(1) The double bond hydrogenation rate of the conjugated diene compound derived from the hydrogenated copolymer composition was determined by nuclear magnetic resonance spectroscopy (NMR) under the following conditions to determine the block rate and vinyl group in the hydrogenated copolymer composition. In addition, during the determination, the liquid after the hydrogenation reaction was put into a large amount of methanol to precipitate the hydrogenated copolymer composition and recover it. Then, the hydrogenated copolymer composition was extracted with acetone, and the extract was vacuum dried and used as a sample for ¹ H-NMR determination. The measurement conditions are described below. (Measurement conditions) Measurement equipment: JNM-LA400 (manufactured by JEOL) Solvent: deuterated chloroform Measurement sample: Samples before and after polymer hydrogenation Sample concentration: 50 mg/mL Observation frequency: 400 MHz Chemical transfer standard: CDCl ₃ (deuterated chloroform) Pulse display: 2.904 seconds Scanning times: 256 times Pulse width: 45 ^° Measurement temperature: 26 °C

(2) Melt flow rate (MFR) of hydrogenated copolymer composition According to ISO 1133, the MFR (g/10 min) of the hydrogenated copolymer composition was measured at a temperature of 230°C and a load of 21.17 N (2.16 kgf).

(3) Vinyl aromatic monomer content of hydrogenated copolymer composition A certain amount of hydrogenated copolymer composition was dissolved in chloroform and measured using an ultraviolet spectrophotometer (manufactured by Shimadzu Corporation, UV-2450). The vinyl aromatic monomer content in the hydrogenated copolymer composition was calculated using a calibration curve based on the peak intensity of the absorption wavelength (262 nm) caused by the vinyl aromatic compound (styrene).

(4) Initial adhesion Using a roller press (special compression roller manufactured by Yasuda Seiki Co., Ltd. (hardness A80, weight 2kg)), each layer of film was temperature-controlled and humidified at 23°C and relative humidity 50% for 24 hours, and then laminated to the lens surface of the prism sheet at a lamination pressure of 0.35MPa and a lamination speed of 3m/min so that the lens surface was covered. After that, the film was stored at 23°C and relative humidity 50% for 24 hours, and then the adhesion was evaluated. In addition, the prism sheet used was a prism sheet with a gap of 25μm between prism ridges made of 95μm thick acrylic resin.

Adhesion was measured using a tensile tester (Orientec Co., Ltd. universal testing machine "tensilon") at a peeling speed of 300 mm/min and a peeling angle of 180 degrees. The measurement was performed 5 times, and the average value was taken as the initial adhesion. (Judgment criteria) Adhesion (initial) Excellent: 10mN/25mm or more, less than 100mN/25mm Good: 100mN/25mm or more, less than 300mN/25mm Poor: less than 10mN/25mm, 300mN/25mm or more

(5) Adhesion over time (adhesion enhancement) In the same manner as the initial adhesion test (4) above, each layer of film was attached to the lens surface of the prism sheet in such a way that it covered the lens surface. After that, it was stored in a hot air oven at a temperature of 50°C for 72 hours, and then stored at a temperature of 23°C and a relative humidity of 50% for 24 hours before the adhesion evaluation was performed.

Adhesion was measured using a tensile tester (Orientec Co., Ltd. universal testing machine "Tensilon") at a peeling speed of 300 mm/min and a peeling angle of 180 degrees. The measurement was performed three times, and the average value was used as the adhesion over time. The peel strength measured in this way was used as the adhesion over time, and the change rate of the adhesion over time from the initial adhesion (adhesion enhancement rate) was calculated using the following formula. Adhesion enhancement rate (%) = (adhesion over time/initial adhesion) × 100 (%) (Judgment criteria) Adhesion enhancement rate Excellent: 80% or more, less than 150% Good: 150% or more, less than 250% Poor: 250% or more

(6) Evaluation of heating floating In the same manner as the initial adhesion test (4) above, each layer of film was attached to the lens surface of the prism sheet in such a way that it covered the lens surface. After that, it was stored in a hot air oven at a temperature of 50°C for 72 hours, and then stored at a temperature of 23°C and a relative humidity of 50% for 24 hours. The floating of the surface protective film from the prism sheet was visually evaluated. The case where no floating was observed was evaluated as good, and the case where floating was observed was evaluated as poor.

(7) Evaluation of paste residue (contamination) In the same manner as the initial adhesion test (4) above, each surface protection film is attached to the lens surface of the prism sheet in such a way that it covers the lens surface. After being placed in an environment of 60°C for 30 minutes, the surface protection film is peeled off and the presence of paste residue on the prism sheet is visually evaluated. (Judgment criteria) Good: No paste residue is observed on the prism sheet Poor: Paste residue is observed on the prism sheet

(Production of hydrogenated copolymer composition) (Production example) Using a tank reactor equipped with a stirring device and a jacket, cyclohexane is used as a solvent, and n-butyl lithium (hereinafter referred to as Bu-Li) is used as a polymerization catalyst. First, a predetermined amount of butadiene monomer (I) is added to terminate the polymerization, then a predetermined amount of styrene monomer is added to terminate the polymerization, and then a predetermined amount of butadiene monomer (II) is added to terminate the polymerization. After the polymerization is completed, tetraethoxysilane is added as a coupling agent to crosslink a portion of the butadiene-styrene-butadiene copolymer, thereby obtaining a mixture of the butadiene-styrene-butadiene copolymer and its crosslinked product (copolymer composition).

Subsequently, a predetermined amount of dicyclopentadiene titanium chloride and trimethylaluminum were added to the obtained polymerization solution as hydrogenation catalysts to hydrogenate the double bonds derived from butadiene. After the reaction was completed, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate was added as an antioxidant to obtain the desired hydrogenated copolymer composition (the hydrogenated product in the following examples). The composition and physical properties of the obtained hydrogenated copolymer composition are shown in Table 1.

(Example 1) As a hydrogenated copolymer composition, the hydrogenated product 1 obtained in the production example was 85% by weight and the aromatic hydrocarbon resin "FTR" 8100 manufactured by Mitsui Chemicals Co., Ltd. was 15% by weight, and the mixture was dry-mixed to prepare a resin layer (b).

The base material (a) used was "primepolypro" F113G manufactured by Prime Polymer Co., Ltd., which is homogeneous polypropylene (homogeneous polypropylene) having an MFR of 3.0 g/10 minutes.

The resins of the resin layer (b) and the substrate layer (a) were fed into two types of two-layer T-molding film machines equipped with two single-screw extruders with a compression ratio of 4.2 and L/D=25, and cast in a manner such that the resin layer (b) side was in contact with a metal cooling drum whose temperature was controlled at 30°C. The films were cooled and solidified to obtain a laminated film having a resin layer (b) thickness of 4μm, a substrate layer (a) thickness of 36μm, and an overall thickness of 40μm.

(Example 2) Except that the composition of the resin layer (b) of Example 1 is changed as follows, a film with an overall thickness of 40 μm is obtained in the same manner as in Example 1. ‧Hydride 2 obtained in the manufacturing example: 85 wt% ‧"FTR" 8100: 15 wt%

(Example 3) Except that the composition of the resin layer (b) of Example 1 is changed as follows, a film with an overall thickness of 40 μm is obtained in the same manner as in Example 1. ‧Hydride 3 obtained in the manufacturing example: 85 wt% ‧"FTR" 8100: 15 wt%

(Example 4) Except that the composition of the resin layer (b) of Example 1 is changed as follows, a film with an overall thickness of 40 μm is obtained in the same manner as in Example 1. ‧Hydride 4 obtained in the manufacturing example: 85 wt% ‧"FTR" 8100: 15 wt%

(Example 5) Except that the composition of the resin layer (b) of Example 1 is changed as follows, a film with an overall thickness of 40 μm is obtained in the same manner as in Example 1. ‧Hydride 5 obtained in the manufacturing example: 85 wt% ‧"FTR" 8100: 15 wt%

(Example 6) Except that the composition of the resin layer (b) of Example 1 is changed as follows, a film with an overall thickness of 40 μm is obtained in the same manner as in Example 1. ‧Hydrogenated product 1 obtained in the production example: 85 wt% ‧Terpene phenol resin YS POLYSTAR TH130 manufactured by Yasuhara Chemical Co., Ltd.: 15 wt%

(Example 7) Except that the thickness of the resin layer (b) is changed to 25μm and the thickness of the substrate layer (a) is changed to 15μm as in Example 1, a laminated film with an overall thickness of 40μm is obtained in the same manner as in Example 1.

(Example 8) Except that the thickness of the resin layer (b) is changed to 2μm and the thickness of the substrate layer (a) is changed to 38μm as in Example 1, a laminated film with an overall thickness of 40μm is obtained in the same manner as in Example 1.

(Example 9) In addition to the composition shown in Example 1, a second resin layer (c) is formed on the opposite side of the substrate layer (a) where the resin layer (b) is formed, and the resins of the resin layer (b), the substrate layer (a) and the second resin layer (c) are placed in a short-axis spiral having a compression ratio of 4.2 and L/D=25. The three types of three-layer T-molding film machines of the extruder are cast by making the resin layer (b) contact the metal cooling drum controlled at 30°C, and then cooled and solidified to produce a film. The obtained three-layer laminated film includes a resin layer (b) with a thickness of 4μm, a base layer (a) and a second resin layer (c) with a total thickness of 36μm, and an overall thickness of 40μm. ‧ Block PP resin "topilen" J640F manufactured by Hirosei Japan Co., Ltd.: 90 wt% ‧ Olefin-silicone copolymer "exfore" PP masterbatch manufactured by Mitsui Chemicals Co., Ltd.: 10 wt% (Comparative Example 1) Except that the composition of the resin layer (b) of Example 1 is changed as follows, a film with an overall thickness of 40 μm is obtained in the same manner as Example 1. ‧ Hydrogenated product 6 obtained in the manufacturing example: 85 wt% ‧ "FTR" 8100: 15 wt%

(Comparative Example 2) Except that the composition of the resin layer (b) of Example 1 is changed as follows, a film with an overall thickness of 40 μm is obtained in the same manner as Example 1. ‧Hydride 7 obtained in the manufacturing example: 85 wt% ‧"FTR" 8100: 15 wt%

(Comparative Example 3) Except that the composition of the resin layer (b) of Example 1 is changed as follows, a film with an overall thickness of 40 μm is obtained in the same manner as Example 1. ‧Hydride 8 obtained in the manufacturing example: 85 wt% ‧"FTR" 8100: 15 wt%

(Comparative Example 4) Except that the composition of the resin layer (b) of Example 1 is changed as follows, a film with an overall thickness of 40 μm is obtained in the same manner as Example 1. ‧Hydride 9 obtained in the manufacturing example: 85 wt% ‧"FTR" 8100: 15 wt%

(Comparative Example 5) Except that the composition of the resin layer (b) of Example 1 is changed as follows, a film with an overall thickness of 40 μm is obtained in the same manner as Example 1. ‧Hydride 1 obtained in the manufacturing example: 100 wt%

(Comparative Example 6) Except that the composition of the resin layer (b) of Example 1 is changed as follows, a film with an overall thickness of 40 μm is obtained in the same manner as in Example 1. ‧JSR (stock) hydrogenated styrene butadiene rubber "DYNARON" 1321P (hydrogenated copolymer without butadiene monomer terminals): 85 wt% ‧"FTR" 8100: 15 wt%

[Table 1] Unit Hydrogen 1 Hydrogen 2 Hydrogen 3 Hydrogen 4 Hydrogen 5 Hydrogen 6 Hydrogen 7 Hydrogen 8 Hydrogen 9 Butadiene (I) addition amount Quality 4 2 4 4 5 5 4 4 5 Styrene addition Quality 10 12 8 10 10 35 4 10 10 Butadiene (II) addition amount Quality 86 86 88 86 85 60 92 86 85 Hydrogenation rate mol% 99 99 99 99 99 99 99 99 99 MFR g/10 minutes 9 7 10 16 6 9 9 35 2

[Table 2] Hydrogenated copolymer composition Tackifying resin Adhesive layer thickness Layer composition Initial adhesion Adhesion enhancement Heating Float Paste residue (contamination) weight% weight% μm mN/25mm determination % determination determination determination Embodiment 1 Polymer 1 (Hydrogenated Compound 1) 85 FTR 8100 15 4 2 types 2 layers 50 Excellent 100 Excellent good good Embodiment 2 Polymer 2 (Hydrogenated 2) 85 FTR 8100 15 4 2 types 2 layers 40 Excellent 130 Excellent good good Embodiment 3 Polymer 3 (Hydrogenated 3) 85 FTR 8100 15 4 2 types 2 layers 80 Excellent 220 good good good Embodiment 4 Polymer 4 (Hydrogenated 4) 85 FTR 8100 15 4 2 types 2 layers 160 good 180 good good good Embodiment 5 Polymer 5 (Hydrogenated 5) 85 FTR 8100 15 4 2 types 2 layers 30 Excellent 80 Excellent good good Embodiment 6 Polymer 1 (Hydrogenated Compound 1) 85 TH130 15 4 2 types 2 layers 80 Excellent 150 Excellent good good Embodiment 7 Polymer 1 (Hydrogenated Compound 1) 85 FTR 8100 15 25 2 types 2 layers 210 good 230 good good good Embodiment 8 Polymer 1 (Hydrogenated Compound 1) 85 FTR 8100 15 2 2 types 2 layers 10 Excellent 80 Excellent good good Embodiment 9 Polymer 1 (Hydrogenated Compound 1) 85 FTR 8100 15 4 3 types, 3 layers 50 Excellent 110 Excellent good good Comparison Example 1 Polymer 6 (Hydrogenated 6) 85 FTR 8100 15 4 2 types 2 layers 3 bad 80 Excellent bad good Comparison Example 2 Polymer 7 (Hydrogenated 7) 85 FTR 8100 15 4 2 types 2 layers 180 good 320 bad good bad Comparison Example 3 Polymer 8 (Hydrogenated 8) 85 FTR 8100 15 4 2 types 2 layers 530 bad 350 bad good bad Comparison Example 4 Polymer 9 (Hydrogenated 9) 85 FTR 8100 15 4 2 types 2 layers 10 Excellent 220 good bad good Comparison Example 5 Polymer 1 (Hydrogenated Compound 1) 100 - 0 4 2 types 2 layers 20 Excellent 80 Excellent bad good Comparative Example 6 DYNARON1321P 85 FTR 8100 15 4 2 types 2 layers 30 Excellent 80 Excellent bad good

Examples 1 to 8 are extremely well balanced in terms of initial adhesion to the optical sheet surface, suppression of adhesion enhancement, suppression of floating after heating, and suppression of contamination of the adherend. On the other hand, in Comparative Examples 1, 4, 5, and 6, the laminated film is heated after being bonded to the adherend, resulting in undesirable film peeling. In Comparative Examples 2 and 3, the adhesion enhancement is increased after being heated after being bonded to the adherend, resulting in undesirable adhesive residues on the adherend surface and paste residues (contamination) on the adherend surface. [Possibility of industrial use]

The laminated film of the present invention is not only a surface protection film that can prevent damage and contamination of adherends with uneven surfaces, but can also be preferably used as a surface protection film for various products made of various materials including synthetic resins, metals, glass, etc.

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Claims (10)

A laminate film having a resin layer (b) on one surface of a substrate layer (a), wherein the resin layer (b) is a resin composition containing a hydrogenated copolymer composition and a tackifying resin, and the hydrogenated copolymer composition satisfies the following (1) to (3): (1) the hydrogenated copolymer composition is composed of a polymer block A mainly composed of a vinyl aromatic monomer unit and a polymer block B mainly composed of a covalent diene monomer unit, and has a structural formula of B-A-B; (2) the content of the vinyl aromatic monomer unit in the hydrogenated copolymer composition as a whole is 5 to 30% by weight; (3) the melt flow rate of the hydrogenated copolymer composition is 3 to 30 g/10 minutes. A laminated film as claimed in claim 1, wherein more than 81 mol% of the double bonds of the covalent diene monomer units contained in the hydrogenated copolymer composition of the resin layer (b) are hydrogenated. The laminated film of claim 1 or 2, wherein the thickness of the resin layer (b) is 1-30 μm. The laminated film of claim 1 or 2, wherein the tackifying resin of the resin layer (b) is at least one resin selected from the group consisting of aliphatic petroleum resins, aromatic petroleum resins, aliphatic/aromatic petroleum resins, alicyclic petroleum resins, terpene resins, terpene phenol resins, rosin resins, alkylphenol resins and xylene resins. As in the laminated film of claim 1 or 2, the content of the thickening resin in the resin composition of the resin layer (b) is 3-30% by weight. A laminated film as claimed in claim 1 or 2, wherein the other side of the substrate layer (a) has a second resin layer (c). A method for manufacturing a laminated film, which is a method for manufacturing a laminated film as claimed in any one of claims 1 to 6, wherein the substrate layer (a) and the resin layer (b) are formed by melt co-extrusion. A method for manufacturing a laminated film, which is the method for manufacturing a laminated film as claimed in claim 6, wherein the substrate layer (a), the resin layer (b) and the second resin layer (c) are formed by melt co-extrusion. A method for producing a laminated film, which is a method for producing a laminated film as claimed in any one of claims 1 to 6, wherein the hydrogenated copolymer composition of the resin layer (b) is obtained by completing the polymerization of a butadiene monomer, then completing the polymerization of a styrene monomer, and then adding a coupling agent after completing the polymerization of the butadiene monomer to crosslink a portion of the butadiene-styrene-butadiene copolymer, and adding a hydrogenation catalyst to the obtained copolymer and its crosslinked product to hydrogenate the double bonds. For example, the laminated film in claim 1 or 2 is used as a protective film for the surface of a prism.