JP5072212B2 - Surface protection film - Google Patents

Description

  The present invention relates to a surface protective film. More specifically, it has cleanness such as firmness, low powderiness, and excellent antifouling properties, and also has excellent adhesive strength over time, for metal plates, for resin plates, for wooden decorative plates, for nameplates The present invention relates to a surface protective film suitably used for building materials, automobile parts, particularly for liquid crystal members, electric and electronic parts, and the like.

In general, the surface protective film is composed of a single layer or a multi-layer base material layer made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or a resin composition obtained by mixing these, and an adhesive layer. Used on metal plates, resin plates, wooden decorative plates, nameplates, liquid crystal members, electrical and electronic parts, building materials, automobile parts, etc. for the purpose of preventing scratches and dirt generated from outside during transportation and storage. ing.
When the base material layer is made of polyethylene, it is known that linear polyethylene such as high-density polyethylene or linear low-density polyethylene is used alone or mixed with high-pressure low-density polyethylene. For example, Patent Document 1 discloses a method in which high-density polyethylene is used alone as a base material layer, Patent Document 2 discloses a method in which high-density polyethylene is mixed with a high-pressure method low-density polyethylene, and Patent Document 3 further. Each discloses a method of using linear low density polyethylene alone.
However, the use of linear polyethylene makes it possible to improve the mechanical strength of the surface protective film, the punching processability, and the fluffing property when cutting with a saw blade or router, but especially for liquid crystal members and electrical and electronic equipment. The current situation is that it has not yet satisfied the cleanliness level of demand for parts.
Furthermore, in recent years, the thinning of liquid crystal members has been progressing, and the surface protection film is required not only to prevent scratches and dirt, but also to serve as a support for the members. It has become a requirement to have, but it remains a problem that it is not responding to it.

Japanese Patent Application Laid-Open No. 08-170056 JP 54-133578 A Japanese Patent Laid-Open No. 06-328633

  The present invention was made in view of the situation as described above, and has cleanliness such as strength and low powderiness, excellent antifouling properties, and further excellent in temporal stability of adhesive strength, It is an object to provide a surface protective film that is suitably used for metal plates, resin plates, wooden decorative plates, nameplates, building materials, automotive parts, particularly for liquid crystal members and electrical and electronic parts. To do.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a specific linear polyethylene is used for the base material layer to meet the above-mentioned purpose. The invention has been completed.
That is, the present invention is as follows.
[1] A surface protective film comprising a base material layer and an adhesive layer, wherein the base material layer is made of linear polyethylene, and the linear polyethylene has a density of 930 kg / m ³ or more and a melt mass flow rate of 0.1 g. / 10 min to 50 g / 10 min, the molecular weight distribution represented by the ratio of the weight average molecular weight to the number average molecular weight obtained by gel permeation chromatography is from 2 to 10, and the converted molecular weight in the linear polyethylene is 10 ^5. Surface protection characterized by being a linear polyethylene having a ratio of the amount of methyl groups contained in a component having a converted molecular weight of 10 ³ or more and 10 ⁴ or less to the amount of methyl groups contained in the component of 10 ⁶ or less. the film.
[2] The surface protective film as described in [1] above, wherein the linear polyethylene is a linear polyethylene obtained by a polymerization method using a supported geometrically constrained single site catalyst.
[3] The surface protective film according to the above [1] or [2], wherein the linear polyethylene is a linear polyethylene that does not contain any of a filler, a slip agent, and an antioxidant.

  According to the present invention, it has both cleanness such as firmness and low powderiness, excellent antifouling properties, and further excellent in the temporal stability of adhesive strength, for metal plates, for resin plates, for wooden decorative plates, It is possible to provide a surface protective film that is suitably used for nameplates, building materials, automobile parts, particularly liquid crystal members, and electric / electronic parts.

Hereinafter, the present invention will be described in detail.
In the surface protective film of the present invention, the base material layer is composed of linear polyethylene, and the linear polyethylene has a density of 930 kg / m ³ or more, preferably 932 kg / m ³ or more, melt mass flow rate (hereinafter abbreviated as “MFR”). .) Is 0.1 g / 10 min or more and 50 g / 10 min or less, preferably 0.3 g / 10 min or more and 40 g / 10 min or less, and the weight average with respect to the number average molecular weight obtained by gel permeation chromatography (hereinafter abbreviated as “GPC”). The molecular weight distribution represented by the molecular weight ratio is 2 or more and 10 or less, preferably 3 or more and 7 or less, with respect to the amount of methyl groups contained in the component having a converted molecular weight of 10 ⁵ or more and 10 ⁶ or less in the linear polyethylene. the ratio of the equivalent molecular weight of 10 ³ 10 ⁴ methyl groups content in the following ingredients (hereinafter referred to as "methyl volume ratio".) is Less than 2.0, preferably less than 0.9. In the surface protective film of the present invention, when the density, MFR, molecular weight distribution, and methyl group ratio of the linear polyethylene in the base material layer are within the above ranges, the strength and low powderiness, excellent antifouling properties In addition, it has excellent clean properties such as adhesive properties, and has excellent adhesive strength over time. For metal plates, resin plates, wooden decorative plates, nameplates, building materials, automotive parts, especially for liquid crystal components, electric and electronic The object of providing a surface protective film suitably used for parts and the like can be achieved.

The problems when the density, MFR, molecular weight distribution, and methyl group concentration ratio of the linear polyethylene of the base material layer in the surface protective film of the present invention are outside the above ranges will be described below.
If the density is less than 930 kg / m ³ , the stiffness of the film will be insufficient, and the suitability of the object to be protected will be impaired, and the film will be easily wrinkled. When the MFR is less than 0.1 g / 10 min, the high-speed film forming property and the coextrusion property are deteriorated. If the MFR exceeds 50 g / 10 min, there will be problems in molding processing such as bubble destabilization during inflation film formation and neck-in increase during T-die film formation. Moreover, low powder property is also impaired.
When the molecular weight distribution is less than 2, the extrusion load at the time of molding increases, and when it exceeds 10, the problem of low powderiness deterioration and the amount of smoke generation at the time of molding increases. Furthermore, when the methyl group amount ratio is 1.0 or more, low powderiness and stability with time of adhesive force deteriorate.
In addition, in the molecular weight distribution measurement by GPC which will be described later, the methyl group amount ratio is measured by the same method except that the sample concentration is changed, and at the same time, infrared spectroscopic analysis of the eluted components is made by Perkin Elmer; FT -IR absorbance I (methylene) attributable to a methylene group by performing the spectrum 2000 (absorption wave: 2925 cm ^-1) and the absorbance I (methyl) (absorption wave: 2960 cm ^-1) attributed to a methyl group ratio of both the The methyl group concentration can be obtained from I (methyl) / I (methylene) and multiplied by the weight percent of the eluted component, which will be described in detail later.

The linear polyethylene of the base material layer in the surface protective film of the present invention must be obtained by a polyethylene polymerization method using a supported geometrically constrained single site catalyst. Various known methods can be used as the polymerization method, such as fluidized bed gas phase polymerization or stirring gas phase polymerization in an inert gas, slurry polymerization in an inert solvent, bulk polymerization using a monomer as a solvent, and the like. Although mentioned, slurry polymerization in an inert solvent is preferable.
The linear polyethylene of the base material layer in the surface protective film of the present invention may be a homopolymer composed of ethylene alone or a copolymer polymer composed of ethylene and an α-olefin having 3 to 20 carbon atoms. Examples of the α-olefin having 3 to 20 carbon atoms to be copolymerized with propylene, butene-1, pentene-1, hexene-1, octene-1, decene-1, dodecene-1, tetradecene-1, hexadecene-1, Examples include octadecene-1, eicosene-1, 3-methyl-butene-1, 4-methyl-pentene-1, 6-methyl-heptene-1. Two or more of these may be dry blended or melt blended at an arbitrary ratio.

The supported geometrically constrained single-site catalyst (hereinafter abbreviated as “metallocene catalyst”) used in the above polymerization method is (a) a carrier material, (b) an organoaluminum, and (c) a cyclic η-binding anion. It is prepared from a transition metal compound having a ligand, and (d) an activator capable of reacting with the transition metal compound having the cyclic η-bonding anion ligand to form a complex that exhibits catalytic activity. Japanese Patent Laid-Open No. 11-166209 discloses that titanium is used as a transition metal atom in the transition metal compound having a cyclic η-bonding anion ligand (c).
The carrier substance (a) may be either an organic carrier or an inorganic carrier. As the organic carrier, preferably (1) an α-olefin polymer having 2 to 20 carbon atoms, such as polyethylene, polypropylene, polybutene-1, ethylene / propylene copolymer, ethylene / hexene-1 copolymer, Propylene / butene-1 copolymer, ethylene / hexene-1 copolymer, etc., (2) aromatic unsaturated hydrocarbon copolymer, such as polystyrene, styrene / divinylbenzene copolymer, and (3) polar Group-containing polymer polymers such as polyacrylic acid esters, polymethacrylic acid esters, polyacrylonitrile, polyvinyl chloride, polyamide, polycarbonate and the like. The inorganic carrier (4) an inorganic oxide, _{e.g., SiO 2, Al 2 O 2} , MgO, TiO 2, B 2 0 3, CaO, ZnO, BaO, ThO, SiO 2 -MgO, SiO 2 -Al 2 O ₃ , SiO ₂ —MgO, SiO ₂ —V ₂ O _5, etc. (5) Inorganic halogen compounds such as MgCl ₂ , AlCl ₃ , MnCl _2, etc. (6) Inorganic carbonates, sulfates, nitrates such as Na ₂ CO ₃ , K ₂ CO ₃ , CaCO ₃ , MgCO ₃ , Al ₂ (SO ₄ ) ₃ , BaSO ₄ , KNO ₃ , Mg (NO ₃ ) _2, etc. (7) Hydroxides such as Mg (OH ) ₂ , Al (OH) ₃ , Ca (OH) _{3 and the} like. The most preferred carrier is SiO _2.
The particle size of the carrier is arbitrary, but generally 1 μm to 3000 μm. From the viewpoint of particle dispersibility, the particle size distribution is preferably in the range of 10 to 1000 μm.

The carrier material is treated with (a) an organoaluminum compound as necessary. As a preferable organoaluminum compound, a linear or cyclic polymer represented by the general formula (—Al (R) O—) _n (wherein R is a hydrocarbon group having 1 to 10 carbon atoms, Including those substituted with a partial halogen atom and / or RO group, where n is the degree of polymerization and is 5 or more, preferably 10 or more.) Specific examples include R as a methyl group, an ethyl group, Examples thereof include methylalumoxane, ethylalumoxane, and isobutylethylalumoxane, which are isobutylethyl groups.
Still other organoaluminum compounds include trialkyl aluminum, dialkyl halogeno aluminum, sesquialkyl halogeno aluminum, armenyl aluminum, dialkyl hydroaluminum, sesquialkyl hydroaluminum and the like.

  Specific examples of other organoaluminum compounds include trialkylaluminum such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, and trioctylaluminum, dialkylhalogenoaluminum such as dimethylaluminum chloride and diethylaluminum chloride, and sesquimethylaluminum. Examples thereof include sesquialkyl halogenoaluminums such as chloride and sesquiethylaluminum chloride, ethylaluminum dichloride, diethylaluminum hydride, diisobutylaluminum hydride, and sesquiethylaluminum hydride. Of these, trimethylaluminum, triethylaluminum, triisobutylaluminum, diethylaluminum hydride and diisobutylaluminum hydride are most preferred.

式中、Ｍは１つ以上の配位子Ｌとη⁵ 結合をしている酸化数＋２、＋３、＋４の長周期型周期律表第４族遷移金属であり、特に遷移金属としてはチタニウムが好ましい。
又Ｌは環状η結合性アニオン配位子であり、各々独立にシクロペンタジエニル基、インデニル基、テトラヒドロインデニル基、フルオレニル基、テトラヒドロフルオレニル基、またはオクタヒドロフルオレニル基であり、これらの基は２０個までの非水素原子を含む炭化水素基、ハロゲン、ハロゲン置換炭化水素基、アミノヒドロカルビ基、ヒドロカルビオルオキシ基、ジヒドロカルビルアミノ基、ジヒドロカルビルフォスフィノ基、シリル基、アミノシリル基、ヒドロカルビルオキシシリル基及びハロシリル基から各々独立に選ばれる１〜８の置換基を任意に有していてもよく、さらには２つのＬが２０個までの非水素原子を含むヒドロカルバジイル、ハロヒドロカルバジイル、ヒドロカルビレンオキシ、ヒドロカルビレンアミノ、ジラジイル、ハロシラジイル、アミノシランなどの２価の置換基により結合されていてもよい。 The supported catalyst includes, for example, a transition metal compound having (c) a cyclic η-bonding anion ligand represented by the following formula (1).

In the formula, M is a group 4 transition metal of a long-period type periodic table having an oxidation number of +2, +3, +4 and having an η ⁵ bond with one or more ligands L. preferable.
L is a cyclic η-bonding anion ligand, each independently a cyclopentadienyl group, an indenyl group, a tetrahydroindenyl group, a fluorenyl group, a tetrahydrofluorenyl group, or an octahydrofluorenyl group, These groups are hydrocarbon groups containing up to 20 non-hydrogen atoms, halogens, halogen-substituted hydrocarbon groups, aminohydrocarbyl groups, hydrocarbyloxy groups, dihydrocarbylamino groups, dihydrocarbylphosphino groups, silyl groups, Hydrocarbadiyl optionally having 1 to 8 substituents each independently selected from an aminosilyl group, a hydrocarbyloxysilyl group and a halosilyl group, and further, two L's containing up to 20 non-hydrogen atoms , Halohydrocarbadiyl, hydrocarbyleneoxy, hydrocarbyleneamino, diradi Le, Haroshirajiiru, may be linked by a divalent substituent such as an aminosilane.

Each X is independently a monovalent anionic σ-bonded ligand having up to 60 non-hydrogen atoms, a divalent anionic σ-bonded ligand that binds to M divalently, or M and L Are each a divalent anion σ-bonded ligand that binds with one valence.
X ′ is a neutral Lewis base coordination compound independently selected from phosphine, ether, amine, olefin, and / or conjugated diene each having 4 to 40 carbon atoms.
L is an integer of 1 or 2. p is an integer of 0, 1 or 2, and X is a monovalent anionic σ-bonded ligand or a divalent anionic σ-bonded coordination which binds to M and L each with a single valence. P is less than the formal oxidation number of M when it is a child, or p is smaller than the formal oxidation number of M when X is a divalent anionic σ-bonded ligand that binds to M in a divalent manner. Less than l + 1. Q is 0, 1 or 2. The transition metal compound is preferably 1 = 1 in the above formula (1).

式中、Ｍは形式酸化数＋２、＋３又は＋４のチタニウム、ジルコニウム、ハフニウムであり、特にチタニウムが好ましい。
また、Ｒ³ は各々独立に、水素、炭化水素基、シリル基、ゲルミル基、シアノ基、ハロゲン、又はこれらの複合基であり、各々２０個までの非水素原子を有することができる。又近接するＲ³ 同士がヒドロカルバジイル、ジラジイル、またはゲルマジイル等の２価の誘導体を形成して環状となっていてもよい。
Ｘ" は各々独立にハロゲン、炭化水素基、ヒドロカルビルオキシ基、ヒドロカルビルアミノ基、またはシリル基であり、各々２０個までの非水素原子を有しており、また２つのＸ" が炭素数５〜３０の中性共役ジエン、もしくは２価の誘導体を形成してもよい。
Ｙは、−Ｏ−、−Ｓ−、−ＮＲ^* −、−ＰＲ^* −であり、ＺはＳｉＲ^* ₂ 、ＣＲ^* ₂ 、ＳｉＲ^* ₂ ＳｉＲ^* ₂ 、ＣＲ^* ₂ ＣＲ^* ₂ 、ＣＲ^* ＝ＣＲ^* 、ＣＲ^* ₂ ＳｉＲ^* ₂ またはＧｅＲ^* ₂ であり、ここでＲ^* は各々独立に炭素数１〜１２のアルキル基又はアリール基である。又、ｎは１乃至３の整数である。 For example, a suitable example of the transition metal compound is represented by the following formula (2).

In the formula, M is titanium, zirconium or hafnium having a formal oxidation number of +2, +3 or +4, and titanium is particularly preferable.
Each R ³ is independently hydrogen, a hydrocarbon group, a silyl group, a germyl group, a cyano group, a halogen, or a composite group thereof, and each can have up to 20 non-hydrogen atoms. Further, adjacent R ³ may be cyclic by forming a divalent derivative such as hydrocarbadiyl, diradii, or germanidyl.
X ″ each independently represents a halogen, a hydrocarbon group, a hydrocarbyloxy group, a hydrocarbylamino group, or a silyl group, each having up to 20 non-hydrogen atoms, and two X ″ having 5 to 5 carbon atoms Thirty neutral conjugated dienes or divalent derivatives may be formed.
Y is, -O -, - S -, - NR * -, - PR * - a and, Z is _{^{SiR * 2, CR * 2,}} SiR * 2 SiR * 2, CR * 2 CR * 2, CR * = CR ^* , CR ^* ₂ SiR ^* ₂ or GeR ^* ₂ , where R ^* is each independently an alkyl or aryl group having 1 to 12 carbon atoms. N is an integer of 1 to 3.

Furthermore, as a transition metal compound, a more suitable example is represented by following formula (3) and following formula (4).

In the formula, each R ³ is independently hydrogen, a hydrocarbon group, a silyl group, a germyl group, a cyano group, a halogen, or a composite group thereof, and each may have up to 20 non-hydrogen atoms. The transition metal M is titanium, zirconium or hafnium, with titanium being preferred.
The definitions of Z, Y, X and X ′ are as described above. p is 0, 1 or 2, and q is 0 or 1. However, when p is 2 and q is 0, the oxidation number of M is +4, and X is halogen, hydrocarbon group, hydrocarbyloxy group, dihydrocarbylamino group, dihydrocarbyl phosphide group, hydrocarbyl sulfide group, silyl group Group or a composite group thereof, having up to 20 non-hydrogen atoms.
When p is 1 and q is 0, the oxidation number of M is +3, and X is an allyl group, 2- (N, N-dimethylaminomethyl) phenyl group or 2- (N, N-dimethyl). -A stabilized anionic ligand selected from aminobenzyl groups, or the oxidation number of M is +4 and X is a derivative of a divalent conjugated diene, or both M and X are metallocyclopentene groups Is forming.
When p is 0 and q is 1, the oxidation number of M is +2, and X ′ is a neutral conjugated or non-conjugated diene, optionally substituted with one or more hydrocarbons. Also, X ′ may contain up to 40 carbon atoms and forms a π-type complex with M.

Furthermore, in the present invention, the most suitable examples of the transition metal compound are represented by the following formula (5) and the following formula (6).

In the formula, each R ³ is independently hydrogen or an alkyl group having 1 to 6 carbon atoms. The M is titanium, Y is -O -, - S -, - NR * -, - PR * - a and, Z ^* is _{^{SiR * 2, CR * 2,}} SiR * 2 SiR * 2, CR * 2 _{^{CR * 2, CR * = CR}} *, a CR ^* ₂ SiR _2, or GeR ^* _2, wherein R ^* are each independently hydrogen or a hydrocarbon group, hydrocarbyloxy group, a silyl group, a halogenated alkyl group, halogen Aryl group or a composite group thereof. The R ^* may have up to 20 non-hydrogen atoms, and optionally is Z ^* 2 two medium R ^* s or Z ^* in R ^* and in Y medium R ^* have a circular Also good.
p is 0, 1 or 2, and q is 0 or 1. However, when p is 2 and q is 0, the oxidation number of M is +4, and X is each independently a methyl group or a hydrobenzyl group.
When p is 1 and q is 0, the oxidation number of M is +3 and X is a 2- (N, N-dimethyl) -aminobenzyl group, or the oxidation number of M is +4. X is 2-butene-1,4-diyl.
When p is 0 and q is 1, the oxidation number of M is +2, and X ′ is 1,4-diphenyl-1,3-butadiene or 1,3-pentadiene.

但し式中、［Ｌ−Ｈ］^d+はプロトン付与のブレンステッド酸であり、Ｌは中性ルイス塩基である。また［Ｍ_m Ｑ_t ］^d-は相溶性の非配位性アニオンであり、Ｍは周期律表第５族乃至１５族から選ばれる金属またはメタロイドであり、Ｑは各々独立にヒドリド、ジアルキルアミド基、ハライド、アルコキサイド基、アリロキサイド基、炭化水素基、炭素数２０までの置換炭化水素基であり、またハライドであるＱは１個以下である。又ｍは１乃至７の整数であり、ｔは２乃至１４の整数であり、ｄは１乃至７の整数であり、ｔ−ｍ＝ｄである。 The dienes are examples of asymmetric dienes that form metal complexes, and are actually mixtures of geometric isomers.
In addition, the metallocene catalyst includes (d) an activator capable of forming a complex that reacts with a transition metal compound and exhibits catalytic activity. Usually, in a metallocene catalyst, a complex formed by a transition metal compound and the above activator exhibits high olefin polymerization activity as a catalytically active species.
As an activator, the compound represented by following formula (7) is mentioned, for example.

In the formula, [LH] ^{d +} is a Bronsted acid imparted with protons, and L is a neutral Lewis base. [M _m Q _t ] ^d- is a compatible non-coordinating anion, M is a metal or metalloid selected from Groups 5 to 15 of the periodic table, and Q is independently a hydride or dialkylamide. Group, halide, alkoxide group, allyloxide group, hydrocarbon group, substituted hydrocarbon group having up to 20 carbon atoms, and Q which is a halide is 1 or less. M is an integer from 1 to 7, t is an integer from 2 to 14, d is an integer from 1 to 7, and t−m = d.

但し式中、［Ｌ−Ｈ］^d+はプロトン付与のブレンステッド酸であり、Ｌは中性ルイス塩基である。また［Ｍ_m Ｑ_w （Ｇ_u （Ｔ−Ｈ）_r ）_z ］^d-は相溶性の非配位性アニオンであり、Ｍは周期律表第５族乃至１５族から選ばれる金属またはメタロイドであり、Ｑは各々独立にヒドリド、ジアルキルアミド基、ハライド、アルコキサイド基、アリロキサイド基、炭化水素基、炭素数２０までの置換炭化水素基であり、またハライドであるＱは１個以下である。又ＧはＭ及びＴと結合するｒ＋１の価数を持つ多価炭化水素基であり、ＴはＯ、Ｓ、ＮＲまたはＰＲであり、ここでＲはヒドロカルビル基、トリヒドロカルビルシリル基、トリヒドロカルビルゲルマニウム基、もしくは水素である。
又ｍは１乃至７の整数であり、ｗは０乃至７の整数でありｕは０または１の整数であり、ｒは１乃至３の整数であり、ｚは１乃至８の整数であり、ｗ＋ｚ−ｍ＝ｄである。 A more preferred example of the activator is a compound represented by the following formula (8).

In the formula, [LH] ^{d +} is a Bronsted acid imparted with protons, and L is a neutral Lewis base. Also a _{[M m Q w (G u} (T-H) r) z] d- is a non-coordinating anion compatible, M is a metal or metalloid selected from Group 5 to Group 15 of the periodic table Each Q is independently a hydride, a dialkylamide group, a halide, an alkoxide group, an allyloxide group, a hydrocarbon group or a substituted hydrocarbon group having up to 20 carbon atoms, and the Q as a halide is 1 or less. G is a polyvalent hydrocarbon group having a valence of r + 1 which binds to M and T, and T is O, S, NR or PR, where R is a hydrocarbyl group, a trihydrocarbylsilyl group, a trihydrocarbylgermanium. A group or hydrogen.
M is an integer of 1 to 7, w is an integer of 0 to 7, u is an integer of 0 or 1, r is an integer of 1 to 3, z is an integer of 1 to 8, w + z-m = d.

但し式中、［Ｌ−Ｈ］^d+はプロトン付与のブレンステッド酸であり、Ｌは中性ルイス塩基である。また［ＢＱ₃ Ｑ^* ］^- は相溶性の非配位性アニオンであり、Ｂはホウ素原子、Ｑはペンタフルオロフェニル基であり、Ｑ^* は置換基としてＯＨ基を１つ有する炭素数６〜２０の置換アリール基である。 A more preferred example of the activator is a compound represented by the following formula (9).

In the formula, [LH] ^{d +} is a Bronsted acid imparted with protons, and L is a neutral Lewis base. [BQ ₃ Q ^* ] ⁻ is a compatible non-coordinating anion, B is a boron atom, Q is a pentafluorophenyl group, Q ^* has 6 to 6 carbon atoms having one OH group as a substituent. 20 substituted aryl groups.

  Specific examples of non-coordinating anions include triphenyl (hydroxyphenyl) borate, diphenyl-di (hydroxyphenyl) borate, triphenyl (2,4-dihydroxyphenyl) borate, tri (p-tolyl) phenyl (hydroxyphenyl). ) Borate, tris (pentafluorophenyl) (hydroxyphenyl) borate, tris (2,4dimethylphenyl) (hydroxyphenyl) borate, tris (3,5-dimethylphenyl) (hydroxyphenyl) borate, tris (3,5- Di-trifluoromethylphenyl) (hydroxyphenyl) borate, tris (pentafluorophenyl) (2-hydroxyethyl) borate, tris (pentafluorophenyl) (4-hydroxybutyl) borate, tris (pentafluorophenyl) Nyl) (4-hydroxy-cyclohexyl) borate, tris (pentafluorophenyl) (4- (4′-hydroxyphenyl) phenyl) borate, tris (pentafluorophenyl) (6-hydroxy-2-naphthyl) borate Most preferred is tris (pentafluorophenyl) (hydroxyphenyl) borate.

Specific examples of other preferable compatible non-coordinating anions include borates in which the hydroxy group of the borate exemplified above is replaced with NHR. Here, R is preferably a methyl group, an ethyl group or a tert-butyl group.
Specific examples of the proton-providing Bronsted acid include, for example, triethylammonium, tripropylammonium, tri (n-butyl) ammonium, trimethylammonium, tributylammonium, and tri (n-octyl) ammonium, diethylmethylammonium. , Dibutylmethylammonium, dibutylethylammonium, dihexylmethylammonium, dioctylmethylammonium, didecylmethylammonium, didodecylmethylammonium, ditetradecylmethylammonium, dihexadecylmethylammonium, dioctadecylmethylammonium, diicosylmethylammonium, Trialkyl group-substituted ammonium cations such as bis (hydrogenated tallow alkyl) methylammonium N, N-dimethylanilinium, N, N-diethylanilinium, N, N-2,4,6-pentamethylanilinium, N, N-dimethylbenzylanilinium, etc. Also suitable are dialkylanilinium cations.

  The linear polyethylene of the base material layer in the surface protective film of the present invention does not contain any additive of filler, slip agent and antioxidant. Examples of the filler include aluminosilicate, talc, diatomaceous earth, kaolin, clay and the like, and examples of the slip agent include aliphatic hydrocarbon, higher fatty acid, higher fatty acid metal salt, fatty acid ester of alcohol, wax, higher fatty acid amide, Examples thereof include silicone oil and rosin. Antioxidants include phenolic antioxidants and phosphorus antioxidants, but as phenolic antioxidants, 2,6-di-t-butyl-4-methylphenol (dibutylhydroxytoluene), n- Phosphorus oxidation such as octadecyl-3- (4-hydroxy-3,5-di-t-butylphenyl) propionate, tetrakis (methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)) methane As the inhibitor, tetrakis (2,4-di-t-butylphenyl) -4,4′-biphenylene-di-phosphonite, tris (2,4-di-t-butylphenyl) phosphite, cyclic neopentane And tetraylbis (2,4-t-butylphenyl phosphite).

The term “containing” as used herein means that the above-mentioned filler, slip agent, and antioxidant are added to the linear polyethylene for the purpose of modifying or improving the linear polyethylene. When a trace amount of additives is inevitably mixed therein, or when a trace amount of catalyst or reaction initiator remains, it is not said that it is contained.
Containing fillers, slip agents, and antioxidant additives will impair the antifouling property of the protected material, the adhesiveness with the protected material will deteriorate over time, and the surface of the unprotected material will be damaged. This is not preferable because it causes a problem. In addition, additives other than the above such as an antistatic agent, a neutralizing agent, a pigment, and a colorant may be contained. Examples of the antistatic agent include nonionic active agents, ionic active agents, amphoteric active agents and mixtures thereof, and each may be used alone or in combination of two or more. Examples of the neutralizing agent include various metal stearates, hydrotalcite, etc., and each may be used alone or in combination of two or more.

The linear polyethylene of the base material layer in the surface protective film of the present invention is polymerized using a high-pressure low-density polyethylene, a linear low-density polyethylene obtained by polymerization using a Ziegler catalyst or a metallocene catalyst, and a Ziegler catalyst. High density polyethylene, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / methyl acrylate copolymer, ethylene / methyl acrylate copolymer, ethylene / ethyl acrylate One type or two or more types of thermoplastic resins such as a copolymer, polypropylene, polyethylene terephthalate, and polyamide may be dry blended or melt blended.
The surface protective film of the present invention can be obtained by laminating a base material layer and an adhesive layer by co-extrusion film formation or T-die film formation. Alternatively, the base film is formed by inflation film formation or T-die film formation. Although it can also obtain by apply | coating an adhesive after obtaining by (1), it is not specifically limited.

The adhesive layer of the surface protective film of the present invention is a known adhesive resin such as ethylene / vinyl acetate copolymer, linear low-density polyethylene alone or a thermoplastic resin such as high-pressure low-density polyethylene, synthetic rubber, An elastomer such as natural rubber, an adhesion aid such as a terpene resin, and a petroleum resin may be mixed, and the substrate layer can be laminated by inflation film formation or T-die film formation by a coextrusion method. Or, apply adhesive such as natural rubber, acrylic, polyisobutylene, ethylene / vinyl acetate copolymer, styrene / butylene / styrene copolymer, styrene / ethylene / butylene / styrene copolymer to the base material layer. It can also be a layer. The thickness ratio of the adhesive layer to the base material layer is not particularly limited.
The surface protective film of the present invention is suitably used for metal plates, resin plates, wooden decorative plates, nameplates, building materials, automobile parts, particularly liquid crystal members, and electrical and electronic parts. It is very suitably used as a surface protective film for an optical film that is a liquid crystal member.

The present invention will be specifically described below.
The physical property measurement method and evaluation method are as follows.
(1) Density JIS-K-7112: 1999
(2) Melt mass flow rate (MFR)
JIS-K-7210: 1999 (temperature = 190 ° C., load = 2.16 kg)
(3) Molecular weight distribution The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) obtained from GPC is defined as the molecular weight distribution. GPC measurement is made by Waters; GPCV2000 is used, and columns are made by Showa Denko KK; UT-807 (1) and Tosoh KK; GMHHR-H (S) HT (2) are connected in series. And used under the conditions of mobile phase trichlorobenzene (TCB), column temperature 140 ° C., flow rate 1.0 ml / min, sample concentration 20 mg / 15 ml (TCB), sample dissolution temperature 140 ° C., sample dissolution time 2 hours. Calibration of molecular weight is performed at 12 points in the range of Mw of standard polystyrene manufactured by Tosoh Corporation, and the Mw of each standard polystyrene is multiplied by a coefficient of 0.43 to obtain a molecular weight in terms of polyethylene, elution time and polyethylene Create a primary calibration line from the converted molecular weight plot and determine the molecular weight.

(4) Methyl group ratio The molecular weight distribution is measured in the same manner except that the sample concentration is changed to 20 mg / 10 ml (TCB) in the above molecular weight distribution measurement, and at the same time, infrared spectroscopic analysis of the eluted components is performed by PerkinElmer. From the absorbance I (methylene) attributed to the methylene group (absorption wave number: 2925 cm ⁻¹ ) and the absorbance I (methyl) attributed to the methyl group (absorption wave number: 2960 cm ⁻¹ ) The ratio of I (methyl) / I (methylene) is obtained and the methyl group concentration of the eluted component is calculated (the unit is expressed in units / 1000 (C)). The methyl group amount of the ethylene polymer having a converted molecular weight of 10 ⁵ or more and 10 ⁶ or less in the linear polyethylene represents the same molecular weight as a logarithmic value, that is, 5.0 if the same molecular weight is 10 ⁵ . Then, measure the methyl group concentration of the eluted component divided by the molecular weight increased by 0.03 to 0.04 until reaching 6.0, multiply it by the weight fraction of the eluted component, and sum them up be able to. The methyl group amount of an ethylene polymer having a converted molecular weight of 10 ³ or more and 10 ⁴ or less represents the same molecular weight as a logarithmic value, that is, 3.0 when the molecular weight is 10 ³ , and then reaches 4.0 It can be obtained by measuring the methyl group concentration of the eluted component classified by the molecular weight increased by 0.04 from 0.03, multiplying it by the weight fraction of the eluted component, and summing them. The methyl group amount ratio is calculated by dividing the methyl group amount of an ethylene polymer having a converted molecular weight of 10 ³ or more and 10 ⁴ or less by the methyl group amount of an ethylene polymer having a molecular weight of 10 ⁵ or more and 10 ⁶ or less.

(5) Koshi Using an inflation film-forming film having a thickness of 0.06 mm obtained according to the film production method described below, the 2% tensile modulus in the machine direction and the transverse direction are measured in accordance with JIS-K-2127. Average it. If the average value is 190 MPa or more, it is evaluated that the stiffness is strong. On the other hand, if it is less than that, it is evaluated as defective.
(6) Low powderiness The above-mentioned inflation film-forming film for stiffness evaluation is heated at 50 ° C. for 24 hours, cooled at 23 ° C. for 24 hours, and then brought into contact with the black felt cloth affixed to a fixed roll. While running for 20 m, the powder on the substrate layer surface is accumulated on the felt cloth. The amount and accumulation state of the accumulated powder are visually observed, and it is evaluated that the low powder property is excellent when the powder is not generated or slightly generated but the accumulation is partial. On the other hand, when a lot of powder is generated and the film and felt cloth are continuously accumulated in a band shape at the part where the film begins to contact, it is evaluated that the low powder property is poor. If the amount of powder and the state of accumulation are intermediate between the two, it is evaluated that the low powder property is slightly superior.

(7) Antifouling property A polycarbonate plate having a thickness of 3 mm is heated to 60 ° C., and an inflation film for stiffness evaluation is attached so that the adhesive layer is in contact with it, left at 23 ° C. for 24 hours, and then at 100 ° C. Heat again for 1 hour, then leave at 23 ° C. for 24 hours before peeling off the film. The release surface of the polycarbonate plate is visually observed, and if there is no dirt, it is evaluated that the antifouling property is excellent. If there is dirt, it is evaluated that the antifouling property is inferior.
(8) Stability over time of adhesive strength Inflation film-forming film for stiffness evaluation was attached to a 3 mm-thick polycarbonate plate heated to 60 ° C so that the adhesive layer would come in contact, and left at 23 ° C for 24 hours before peeling. The peel strength is measured under the conditions of a width of 50 mm, a peel angle of 180 degrees, and a tensile speed of 500 mm / min to obtain an initial adhesive strength. The inflation film-forming film for stiffness evaluation is heated at 50 ° C. for 24 hours, and the peel strength is measured in the same manner as described above to obtain the adhesive strength with time. If the adhesive strength with time is 90% or more of the initial adhesive strength, it is evaluated that the temporal stability of adhesive strength is excellent, and if it is less than 90%, it is evaluated as inferior.

[Production of linear polyethylene using metallocene catalyst]
6.2 g (8.8 mmol) of triethylammonium tris (pentafluorophenyl) (4-hydroxyphenyl) borate was added to 4 liters of toluene and stirred at 90 ° C. for 30 minutes. Next, 40 ml of a 1 mol / l trihexylaluminum toluene solution was added to this solution and stirred at 90 ° C. for a minute. On the other hand, silica P-10 (manufactured by Fuji Silysia Co., Ltd .: trade name) was treated in a nitrogen stream at 500 ° C. for 3 hours, and the treated silica was placed in 1.7 l of toluene and stirred. The toluene solution of triethylammonium triethylammonium tris (pentafluorophenyl) (4-hydroxyphenyl) borate and trihexylaluminum was added to this silica slurry solution and stirred at 90 ° C. for 3 hours.
Next, 206 ml of a 1 mol / l trihexylaluminum toluene solution was added, and the mixture was further stirred at 90 ° C. for 1 hour. Thereafter, the supernatant was decanted with 90 ° C. toluene to remove excess trihexylaluminum. 0.218 mol / l dark purple titanium (N-1,1-dimethylethyl) dimethyl (1- (1,2,3,4,5-eta) -2,3,4,5-tetramethyl-2 , 4-Cyclopentadien-1-yl) silanaminate) ((2-) N- (η4-1,3-pentadiene) in 20 ml of ISOPAR TME (US Exxon Chemical Co., Ltd.) solution was added to the above mixture and stirred for 3 hours. A green metallocene catalyst was obtained.
The obtained metallocene catalyst is brought into contact with hydrogen by supplying a necessary amount of hydrogen as a chain transfer agent to the catalyst transfer line and introduced into the polymerization reactor, hexane as the solvent, ethylene as the monomer, and butene-1 as required. Then, each monomer was supplied so as to have a predetermined gas composition, and linear polyethylene was polymerized at a reaction temperature of 75 ° C. and a total pressure of 0.8 MPa. The obtained linear polyethylene was granulated by extrusion at 200 ° C. using an extruder manufactured by Nippon Steel Co., Ltd. (screw diameter; 65 mm, L / D = 28).

[Production of linear polyethylene using Ziegler catalyst]
A 15-liter reactor sufficiently purged with nitrogen was charged with 3 liters of trichlorosilane as a 2 mol / liter n-heptane solution, kept at 65 ° C. with stirring, and the composition formula AlMg ₆ (C ₂ H ₅ ) ₃ ( n-C ₄ H ₉ ) _6.4 (On-C ₄ H ₉ ) 7 liters of an n-heptane solution of an organic magnesium component represented by _5.6 (5 moles in terms of magnesium) was added over 1 hour, and further 1 at 65 ° C. The reaction was allowed to stir for an hour. After completion of the reaction, the supernatant was removed and washed 4 times with 7 liters of n-hexane to obtain a solid material slurry. This solid was separated, dried and analyzed, and as a result, it contained 7.45 mmol of Mg per gram of the solid.
Of these, a slurry containing 500 g of solid was reacted with 0.93 liter of n-butyl alcohol 1 mol / liter n-hexane solution at 50 ° C. for 1 hour with stirring. After completion of the reaction, the supernatant was removed and washed once with 7 liters of n-hexane. This slurry was kept at 50 ° C., and 1.3 liters of n-hexane solution of 1 mol / liter of diethylaluminum chloride was added with stirring and reacted for 1 hour. After completion of the reaction, the supernatant was removed and washed twice with 7 liters of n-hexane. This slurry was kept at 50 ° C., 0.2 liter of n-hexane solution of 1 mol / liter of diethylaluminum chloride and 0.2 liter of n-hexane solution of 1 mol / liter of titanium tetrachloride were added and reacted for 2 hours. After completion of the reaction, the supernatant was removed and the solid catalyst was isolated and washed with hexane until no free halogen was detected. The solid catalyst had 2.3 wt% titanium.
Using the catalyst obtained above, linear polyethylene was produced in the following manner.
In a single-stage polymerization process, polymerization was performed in a polymerization vessel having a volume of 230 liters. The polymerization temperature is 86 ° C. and the polymerization pressure is 0.98 MPa. The Ziegler catalyst synthesized in this polymerization vessel was introduced at a rate of 0.3 g / hr, triisobutylaluminum at 15 mmol / hr, and hexane at a rate of 60 l / hr. To this, ethylene, hydrogen, and if necessary, butene-1 was introduced so as to have a predetermined gas composition, polymerization was performed, and the obtained linear polyethylene was an extruder manufactured by Nippon Steel Co., Ltd. (screw diameter; 65 mm, L / D = 28), n-octadecyl-3- (4-hydroxy-3,5-di-t-butylphenyl) propionate and calcium stearate were added and extruded and granulated at 200 ° C. .

[Production method of film]
This is a three-layer inflation film-forming machine equipped with three extruders with a screw diameter of 50 mmφ, a die with a diameter of 120 mmφ and a gap of 2.5 mm. The inner layer is an adhesive layer with a vinyl acetate concentration of 9% by weight and MFR = 1.0 g / 10 min. A vinyl acetate copolymer is used, and as the base layer, the linear polyethylene or other polyethylene other than the linear polyethylene is used alone or in combination as an intermediate layer or outer layer in contact with the adhesive layer. Extrusion was performed at 180 ° C., and a film having a thickness ratio of the inner layer, the intermediate layer, and the outer layer of 1: 2: 2, that is, a thickness ratio of the pressure-sensitive adhesive layer to the base material layer of 1: 4 was formed under a blow ratio of 2.

[Examples 1 to 6, Reference Examples 7 and 8 ]
Inflation was formed using the ethylene, butene-1 and hydrogen gas compositions shown in Tables 1 and 2 and linear polyethylene using the above metallocene catalyst. Tables 1 and 2 also show the evaluation results of the stability over time of the stiffness, low powder property, antifouling property, and adhesive strength. The thermoplastic resin other than the linear polyethylene used for the base material layer is a high-pressure low-density polyethylene with no additive and a density of 920 kg / m ³ and an MFR of 2.0 g / 10 min. As described above, an ethylene / vinyl acetate copolymer having a vinyl acetate concentration of 9% by weight and MFR = 1.0 g / 10 min was used for the adhesive layer. The resin A used in Tables 1 and 2 is the linear polyethylene described in each example, the resin B is the high-pressure low-density polyethylene, the resin C is the ethylene / vinyl acetate copolymer, The number of shows the weight% when mixed and used.

[Comparative Examples 1-4]
Linear polyethylene was obtained by the production method of linear polyethylene using the Ziegler catalyst with the gas composition of ethylene, butene-1 and hydrogen shown in Table 3, and then the inflation film was formed in the same manner as in Example 1. Table 3 also shows the evaluation results of the stability over time of the stiffness, low powder property, antifouling property, and adhesive strength. Resins A, B, and C shown in Table 3 represent the linear polyethylene described in the comparative example, the high-pressure method low-density polyethylene, and the ethylene / vinyl acetate copolymer, respectively, and the numbers in parentheses are used when mixed. % By weight.

  The surface protective film of the present invention has both cleanliness such as firmness, low powderiness, and excellent antifouling properties, and also has excellent adhesive strength over time, for metal plates, resin plates, and wooden decorative plates It is suitably used for nameplates, building materials, automobile parts, particularly liquid crystal members, and electric / electronic parts.

Claims (3)

A surface protective film comprising a base material layer and an adhesive layer, wherein the base material layer is made of linear polyethylene, and the linear polyethylene has a density of 930 kg / m ³ or more and a melt mass flow rate of 0.1 g / 10 min or more. The molecular weight distribution represented by the ratio of the weight average molecular weight to the number average molecular weight obtained by gel permeation chromatography is 2 to 10, and the converted molecular weight in the linear polyethylene is 10 ^{5 to} 10 A surface protective film, which is a linear polyethylene having a ratio of a methyl group contained in a component having a converted molecular weight of 10 ³ or more and 10 ⁴ or less to a methyl group contained in a component of ⁶ or less.   2. The surface protective film according to claim 1, wherein the linear polyethylene is a linear polyethylene obtained by a polymerization method using a supported geometrically constrained single site catalyst.   The surface protective film according to claim 1 or 2, wherein the linear polyethylene is a linear polyethylene that does not contain any of a filler, a slip agent, and an antioxidant.