JP4244428B2 - Multilayer plastic sheet - Google Patents

Description

【００６７】
表２に示すように、実施例，比較例で用いる（Ｂ）層のエチレン系共重合体のペレットを下記のように略称する。
Ｂ−１：凝集エネルギー密度が６８．７ｃａｌ／ｃｍ³ 、ＭＦＲが１．５ｇ／１０ｍｉｎ、結晶融点が９０℃、ビカット軟化点が６７℃、誘電正接のピーク値が１．６×１０^-2を示す東ソー（株）製エチレン・酢酸ビニル共重合体（ウルトラセン６３０ 酢酸ビニル（ＶＡ）含有率１５重量％）を用いる。
Ｂ−２：凝集エネルギー密度が７０．７ｃａｌ／ｃｍ³ 、ＭＦＲが４．０ｇ／１０ｍｉｎ、結晶融点が７６℃、ビカット軟化点が４６℃、誘電正接のピーク値が２．８×１０^-2を示す東ソー（株）製エチレン・酢酸ビニル共重合体（ウルトラセン６３４ ＶＡ含有率２６重量％）を用いる。
【００６８】
【表２】

【００６９】
次に、実施例及び比較例で用いる多層プラスチックシートの評価方法を説明する。
ｔａｎδ（誘電正接）：ＪＩＳ Ｋ６９１１に準じ、相互誘電ブリッジ法によって、多層プラスチックシートのｔａｎδを求める。ｔａｎδの値が大きいほど、高周波電場内で誘電加熱し易いことを示す。
剥離強度（単位；g/cm）：高周波ウエルド加工した多層プラスチックシートのシール部両端を、インストロン型試験機で引張試験を行う。剥離強度の値が大きいほど、強固に接着している。
ヘイズ（透明性）（単位；％）：ＡＳＴＭ Ｄ１００３に準じ、多層プラスチックシートのヘイズを測定して透明性の基準とした。値が小さいほど透明性が良好である。
ヤング率（柔軟性）（単位；MPa ）：ＡＳＴＭ Ｄ８８２に準じ、多層プラスチックシートの引張弾性率であるヤング率を測定して柔軟性の基準とした。値が小さいほど、柔軟である。
鉛筆硬度（耐受傷性）：ＪＩＳ Ｋ５４００に準じ、多層プラスチックシートの鉛筆引っ掻き試験を測定して耐受傷性の基準とした。鉛筆の芯の硬さで示した値が、硬いほど多層プラスチックシート表面が硬く、耐受傷性が良好である。
【００７０】
（実施例−１〜６及び比較例−１〜４）
Ｔダイを備え、コンバイニングアダプター法の３種５層押出機（口径６５ｍｍφの中間層用単軸押出機×１、口径４０ｍｍφの表層用単軸押出機×２）を用い、表２に示したＢ−１またはＢ−２を中間層用単軸押出機に、表１に示したＡ−１、Ａ−２、Ａ−３、Ａ−４またはＡ−５を表層用単軸押出機に供給し、２３０℃で溶融させ、２種３層多層共押出を行い、エアーナイフ及び表面温度５０℃の冷却ロールで冷却固化して厚み２００μｍ（厚み構成比＝１：８：１）からなる２種３層の多層プラスチックシートを得た。
得られた多層プラスチックシートを評価し、その結果を後述の表３および表４に示した。
【００７１】
【表３】

【００７２】
【表４】

【００７３】
上表から、本発明の実施例は大方、比較例に比べてｔａｎδ及び剥離強度が高く、ヘイズ及びヤング率が低く透明性及び柔軟性に優れることが分かる。また、実施例は鉛筆硬度も確保されている。
【００７４】
【発明の効果】
本発明の多層プラスチックシートは、電気的特性として誘電正接（ｔａｎδ）が大きく高周波ウエルド特性に優れ、その他に透明性、柔軟性、耐受傷性のバランスが優れるという効果を発揮する。
【図面の簡単な説明】
【図１】実施例で用いた連続重合装置のフローシートを示す。
【符号の説明】
１, １０ 重合器
２ 循環配管
３，６ 原料プロピレン配管
４, ８ 未反応ガス配管
５, ９ 重合体抜き出し配管
７ 活性抑制剤導入配管
Ｍ 攪拌機[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multilayer plastic sheet using an olefin copolymer that can replace a soft polyvinyl chloride (PVC) sheet, and particularly to a multilayer plastic sheet excellent in high-frequency weldability.
[0002]
[Prior art]
Currently, olefination of soft PVC sheets has been developed for the purpose of environmental conservation and the like.
For example, the present applicant has previously proposed an agricultural multilayer film made of an olefin resin and having excellent anti-fogging durability (Japanese Patent Laid-Open No. 9-18393).
[0003]
Further, not only for agricultural use, but also for example, various olefination of multi-layer films for packaging foods and the like have been proposed. For example, JP-A-3-133756 discloses a packaging film composed of a heat seal layer and a heat-resistant layer, and JP-A-2-283445 discloses a core layer and two outer layers in which shrinkage force and melting point are specified. The shrink film which consists of is disclosed.
[0004]
By the way, the above-mentioned packaging films are mainly intended for thin thicknesses, and it is particularly flexible that the problem of olefination becomes a problem when producing sheets with thick thicknesses. Lack of properties, transparency, adhesiveness, etc. In such olefination, when a sheet is formed with a single layer, it has become possible to mold a soft PVC sheet that is close to a flexible PVC sheet by using an olefin raw material having a low melting point and improving the sheet molding method.
[0005]
However, the single layer has a problem in the scratch resistance of the finished sheet surface. Therefore, it has been proposed to make multiple layers as described in the above-mentioned publication, but in particular, a polymer having both scratch resistance and adhesion without damaging flexibility and transparency is used for the surface layer, and flexibility and Although it is desired to form a multilayer sheet having adhesiveness with the surface layer, a plastic sheet satisfying conditions suitable for an adhesion method excellent in convenience such as high-frequency welding has not been found.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide an olefin-based multilayer plastic sheet having a large dielectric loss tangent (tan δ) which is an electrical property, excellent in high-frequency weldability, and excellent in balance of transparency, flexibility and scratch resistance.
[0007]
[Means for Solving the Problems]
The present invention is a multilayer plastic sheet having a three-layer structure of (A) / (B) / (A), wherein the (A) layer has a propylene content of 90 to 99% by weight and a crystal melting point of 160 ° C. A crystalline propylene-α-olefin copolymer (hereinafter referred to as “crystalline P”), and a propylene-α-olefin copolymer (hereinafter referred to as “crystalline P”) having an α-olefin content of 10 to 55% by weight. ("Copolymer R")
[Η]_RC= 6.5 dl / g or less;
[Η]_RC/ [Η]_PP= 0.6-1.2; and
([Η]_RC/ [Η]_PP) X (W_PP/ W_RC) = 0.2-4.5
A polypropylene composition in the range of
([Η]_RC: Intrinsic viscosity of copolymer R, [η]_PP: Intrinsic viscosity of crystalline P, W_PP:% By weight of crystalline P based on polypropylene composition, W_RC:% By weight of copolymer R relative to polypropylene composition)
The (B) layer has a cohesive energy density of 60 to 90 cal / cm.^ThreeThe melt flow rate is 1.0 to 15.0 g / 10 min, the crystal melting point is 50 to 120 ° C., the Vicat softening point is 100 ° C. or less, and the peak value of dielectric loss tangent is 5.0 × 10^-3The present invention relates to a multilayer plastic sheet comprising an ethylene copolymer having a frequency of (100 kHz) or higher.
[0008]
The multilayer plastic sheet of the present invention has the layer (B) made of an ethylene copolymer having specific physical properties as a core layer, and the above specific physical properties consisting of crystalline P and copolymer R having a specific composition across the core layer. It is a three-layer structure which made the (A) layer which consists of a polypropylene-type composition which shows this as an outer layer.
[0009]
The multilayer plastic sheet of the present invention has a dielectric loss tangent (tan δ) by specifying the composition and physical properties of the polypropylene-based composition of the (A) layer and the physical properties of the ethylene-based copolymer of the (B) layer as described above. ) And a high-frequency weldability, and a multilayer plastic sheet having a good balance of transparency, flexibility, and scratch resistance can be provided.
Crystalline P is a crystalline copolymer composed of 90 to 99% by weight of polypropylene and 1 to 10% by weight of α-olefin other than propylene, and copolymer R is 10 to 55% by weight of α-olefin other than propylene. % And propylene of 45 to 90% by weight.
[0010]
The polypropylene composition used for the layer (A) of the present invention comprises crystalline P and copolymer R, and [η]_RCIs 6.5 dl / g or less, preferably 1.7 to 2.8 dl / g, [η]._RC/ [Η]_PPIs 0.6 to 1.2, preferably 0.7 to 1.0, and ([η]_RC/ [Η]_PP) X (W_PP/ W_RC) Is in the range of 0.2 to 4.5, preferably 1.0 to 3.0.
[0011]
When the propylene content of the crystalline P is larger than 99% by weight, the high-frequency weld processability is lowered, and when the content is less than 90% by weight, the scratch resistance is lowered. Further, when the crystalline melting point of the crystalline P exceeds 160 ° C., transparency and flexibility are lowered.
Further, [η] of the copolymer R_RCIf it is too large, the film-forming property of the polypropylene-based composition is deteriorated, which causes a problem in terms of productivity. [Η]_RC/ [Η]_PPIs less than 0.6, the flexibility (impact resistance) is poor, and [η]_RC/ [Η]_PPIf is too large, the high-frequency weld processability and transparency will be inferior. Also, ([η]_RC/ [Η]_PP) X (W_PP/ W_RC) Is less than 0.2, the flexibility is lowered, and if it exceeds 4.5, the transparency, the scratch resistance and the high-frequency weldability are lowered.
[0012]
As long as the (A) layer is composed of a polypropylene composition that satisfies the above range, the layer may be composed of two or more kinds of compositions arbitrarily selected within the above composition and / or physical properties.
[0013]
[Η]_RCAnd [η]_PPIs a value measured using tetralin (tetrachloronaphthalene) as a solvent under a temperature condition of 135 ° C.
In the case where a polypropylene composition is obtained by continuously producing crystalline P and copolymer R, [η]_RCIs not directly measurable, so [η] of crystalline P that can be directly measured_PPAnd the intrinsic viscosity of the entire polypropylene composition ([η]_whole) And W_RCFrom the following formula,
[Η]_RC= {[Η]_whole-(1-W_RC/ 100) [η]_PP} / (W_RC/ 100)
[0014]
Examples of the α-olefin used for the production of crystalline P and copolymer R include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, -Hexadecene, 1-octadecene, 1-eicocene, 4-methyl-1-pentene, 3-methyl-1-pentene and the like can be mentioned, and ethylene and 1-butene are preferable.
[0015]
The ethylene-based copolymer used for the (B) layer has a cohesive energy density of 60 to 90 cal / cm.^Three, Preferably 60-75 cal / cm^ThreeThe melt flow rate (MFR) is 1.0 to 15.0 g / 10 min, preferably 1.0 to 5.0 g / min, and the crystal melting point is 50 to 120 ° C., preferably 50 to 100 ° C. The Vicat softening point is 100 ° C. or lower, preferably 40 to 70 ° C., and the peak value of dielectric loss tangent is 5.0 × 10^-3(100 kHz) or more, preferably 10 × 10^-3Each characteristic value is (100 kHz) or more.
[0016]
The cohesive energy density is obtained by squaring the solubility parameter obtained by the Small formula, MFR is melt extruded through a prescribed die at a temperature of 230 ° C. and a load of 21.18 N according to JIS K 7210, Find the weight that flows out per unit time. The peak value of the dielectric loss tangent is also referred to as tan δ, and is determined according to JIS K6911.
[0017]
If each of the above physical properties is out of the above range, all of the flexibility, transparency and high frequency weld processability of the multilayer plastic sheet of the present invention cannot be satisfied. For example, if the cohesive energy density is out of the above range, the transparency and high-frequency weldability are lowered, and if the MFR is out of the above range, the transparency and flexibility are lowered, and the crystalline melting point of the ethylene copolymer is in the above range. If it comes off, flexibility, transparency and high frequency weld processability will decrease, and if the Vicat softening point exceeds 100 ° C, flexibility, transparency and high frequency weld processability will decrease, and the peak value of dielectric loss tangent will be 5.0 × 10^-3If it is less than the range, the high-frequency weld processability is lowered.
[0018]
The ethylene-based copolymer is not particularly limited as long as it is a copolymer of ethylene and a copolymerizable monomer, but an ethylene / vinyl acetate copolymer, an ethylene / methyl methacrylate copolymer is not limited. It is preferably selected from ethylene / glycidyl methacrylate copolymers, ethylene / glycidyl methacrylate / vinyl acetate copolymers and ethylene / ethyl acrylate / maleic anhydride copolymers.
[0019]
The polypropylene composition used in the present invention may be produced by any method as long as the above properties are satisfied. Of course, the crystalline P and the copolymer R used in the present invention are melted separately. Copolymer R may be produced by mixing using a mixing device such as a kneading device, or by producing crystalline P and subsequently copolymerizing propylene and α-olefin in the presence of the crystalline P. And a polypropylene composition may be continuously produced by a multistage polymerization method.
[0020]
More preferably, the polypropylene composition used in the present invention can be produced by the production method shown below.
The process for producing a polypropylene composition is to produce crystalline P in the gas phase in the first stage in the presence of a stereoregular catalyst composed of a titanium-containing solid catalyst component having a large particle size and an organoaluminum compound and an organosilicon compound. A step (first polymerization step) followed by a step (second polymerization step) for continuously producing the copolymer R in the second step.
[0021]
In the production method, the titanium-containing solid catalyst component is an inorganic carrier such as a magnesium compound, silica compound and alumina, or an organic carrier such as polystyrene, and a titanium compound supported on the carrier, and ethers and esters as required on such a carrier. Any known compound can be used as long as it has been reacted with the above electron donating compound.
[0022]
For example, a magnesium compound-alcohol solution is sprayed to form a solid component comprising an alcohol adduct of a magnesium compound, the solid component is partially dried, and then the dried solid component is treated with a titanium halide and an electron donating compound. A titanium-containing solid catalyst component (Japanese Patent Laid-Open No. 3-119003), a magnesium compound dissolved in tetrahydrofuran / alcohol / electron donor, and TiCl_FourExamples thereof include a titanium-containing solid catalyst component (JP-A-4-103604) obtained by treating a magnesium carrier precipitated alone or in combination with an electron donor with a titanium halide and an electron donating compound.
[0023]
As the titanium-containing solid catalyst component, those having an average particle diameter of 25 to 300 μm, preferably 30 to 150 μm are usually used. If the average particle size of the titanium-containing solid catalyst component is 25 μm or less, the powder flowability of the polypropylene composition is significantly impaired, and contamination from the polymerization system due to adhesion to the wall of the polymerization vessel, stirring blades, etc., and discharge from the polymerization vessel Therefore, it is difficult to carry out the powder, which hinders stable operation.
Further, the titanium-containing solid catalyst component preferably has a uniformity in normal distribution of 2.0 or less. If the degree of uniformity exceeds 2.0, the powder flowability of the polypropylene-based composition deteriorates and continuous stable operation becomes difficult.
[0024]
As an organoaluminum compound, the general formula is R¹ _mAlX_3-m(Where R¹Is a hydrocarbon group such as an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aryl group or the like or an alkoxy group, X represents a halogen atom, and m is a positive number of 3 ≧ m ≧ 1.5. Can be suitably used.
[0025]
Specifically, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, trii-butylaluminum, dimethylaluminum chloride, diethylaluminum chloride, sesquimethylaluminum sesquichloride, di-n-propylaluminum Examples include chloride, sesquiethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminum iodide, ethoxydiethylaluminum, and the like, and preferably triethylaluminum is used.
These organoaluminum compounds can be used alone or as a mixture of two or more.
[0026]
As the organosilicon compound, a general formula R² _XR^Three _YSi (OR^Four)_z(Where R²And R^FourIs a hydrocarbon group, R^ThreeRepresents a hydrocarbon group or a hydrocarbon group containing a hetero atom, and 0 ≦ X ≦ 2, 1 ≦ Y ≦ 3, 1 ≦ Z ≦ 3 and X + Y + Z = 4) is used. .
[0027]
Specifically, methyltrimethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, phenylmethyldimethoxysilane, t-butyltrimethoxysilane, t-butyltriethoxysilane, phenyltriethoxysilane, methylethyldimethoxysilane, Examples include methylphenyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, di-t-butyldimethoxysilane, diphenyldimethoxysilane, trimethylmethoxysilane, cyclohexylmethyldimethoxysilane, and trimethylethoxysilane. be able to.
[0028]
Preferably, diisobutyldimethoxysilane, diisopropyldimethoxysilane, di-t-butyldimethoxysilane, cyclohexylmethyldimethoxysilane and diphenyldimethoxysilane are used.
[0029]
These organosilicon compounds can be used singly or as a mixture of two or more.
[0030]
A stereoregular catalyst in which the titanium-containing solid catalyst component, an organoaluminum compound and, if necessary, an organosilicon compound are combined is used for propylene polymerization in the first polymerization step, and the titanium-containing solid catalyst component includes an α-olefin. It is preferable to use a catalyst that has been pre-reacted and pre-activated.
[0031]
In the preactivation treatment of the titanium-containing solid catalyst component, the amount of the organoaluminum compound used is not particularly limited, but usually 0.1 to 40 with respect to 1 mol of titanium atom in the titanium-containing solid catalyst component. Mol, preferably 0.3 to 20 mol, and the α-olefin described below is usually 0.1 to 100 g per gram of the titanium-containing solid catalyst component at 10 to 80 ° C. for 10 minutes to 48 hours, Preferably 0.5 to 50 grams are reacted.
[0032]
In the preactivation treatment, the organosilicon compound may be used in an amount of usually 0.01 to 10 moles, preferably 0.05 to 5 moles per mole of the organoaluminum compound.
Examples of the organoaluminum compound used for the preactivation treatment include the exemplified organoaluminum compounds used for the main polymerization. The organoaluminum compound may be the same as or different from the organoaluminum compound used in the main polymerization, and is preferably triethylaluminum.
[0033]
Moreover, as an organosilicon compound used as needed for a preactivation process, the same kind as the organosilicon compound illustrated above can be mentioned. The organosilicon compound may be the same as or different from the organosilicon compound used in the main polymerization, and is preferably diisobutyldimethoxysilane, diisopropyldimethoxysilane, di-t-butyldimethoxysilane, cyclohexylmethyl. Dimethoxysilane and diphenyldimethoxysilane are used.
[0034]
Examples of the α-olefin used for the preactivation treatment of the titanium-containing solid catalyst component include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene and 1-tetradecene. 1-hexadecene, 1-octadecene, 1-eicocene, 4-methyl-1-pentene, 3-methyl-1-pentene, and the like.
[0035]
These α-olefins may be used alone or as a mixture of two or more other α-olefins. In addition, a molecular weight regulator such as hydrogen can be used in combination in order to regulate the molecular weight of the polymer during the polymerization.
[0036]
The inert solvent used for the preactivation treatment of the titanium-containing solid catalyst component is a polymerization reaction such as hexane, heptane, octane, decane, dodecane, liquid saturated paraffin and other liquid saturated hydrocarbons and silicon oil having a dimethylpolysiloxane structure. It is an inert solvent that does not significantly affect the above. These inert solvents may be either one kind of single solvent or two or more kinds of mixed solvents. When these inert solvents are used, it is preferable to use them after removing impurities such as moisture and sulfur compounds which adversely affect the polymerization.
[0037]
A first polymerization step in which propylene and a small amount of α-olefin are polymerized in the gas phase in the presence of the preactivated titanium-containing solid catalyst component, and then a second polymerization in which propylene and α-olefin are copolymerized. Perform the process continuously. The first polymerization step is not limited to the gas phase polymerization method, and a slurry polymerization method or a bulk polymerization method may be adopted. However, since the second polymerization step continuous thereto is preferably a gas phase polymerization method, It is preferable to employ a gas phase polymerization method for one polymerization step. When a slurry polymerization method or a bulk polymerization method is employed as the second polymerization step, the resulting copolymer may be eluted into the solution, making it difficult to continue stable operation.
[0038]
The polymerization conditions in the first polymerization step differ depending on the polymerization type, but in the case of the gas phase polymerization method, preactivated titanium is mixed and stirred in a polymerization vessel using a certain amount of propylene polymer powder as a dispersant. In the presence of a stereoregular catalyst comprising a solid catalyst component, an organoaluminum compound and an organosilicon compound, the polymerization temperature is usually 20 to 120 ° C., preferably 40 to 100 ° C., and the polymerization pressure is usually atmospheric pressure to 9.9 MPa. Preferably, propylene and a small amount of α-olefin are supplied under the condition of 0.59 to 5.0 MPa to polymerize crystalline P.
[0039]
The use ratio of the organoaluminum compound and the titanium-containing solid catalyst component is Al / Ti = 1 to 500 (molar ratio), preferably 10 to 300. In this case, the number of moles of the titanium-containing solid catalyst component substantially refers to the number of Ti gram atoms in the titanium-containing solid catalyst component.
[0040]
The use ratio of the organosilicon compound (C) and the organoaluminum compound (B) is B / C = 1 to 10 (molar ratio), preferably 1.5 to 8.
When the molar ratio of B / C is excessive, the crystallinity of the crystalline P is lowered, and the composition has insufficient rigidity. On the other hand, when the B / C molar ratio is too small, the polymerization activity is remarkably lowered and the productivity is lowered.
[0041]
[Η] of crystalline P_PPIs preferably adjusted by adjusting the molecular weight by using a molecular weight regulator such as hydrogen during the polymerization. After polymerizing crystalline P, a part of the produced powder polymer can be extracted and used for measurement of intrinsic viscosity, melt flow rate, and polymer yield per unit weight of catalyst.
[0042]
Subsequent to the polymerization of propylene in the first polymerization step, the polymerization temperature is usually 20 to 120 ° C., preferably 40 to 100 ° C., and the polymerization pressure is usually atmospheric pressure to 9.9 MPa, preferably 0.59 to 5.0 MPa. The 2nd superposition | polymerization process which co-polymerizes the mixed monomer of propylene and an alpha olefin on condition of this, and produces | generates the copolymer R is implemented.
The ethylene content in the copolymer R is controlled by controlling the molar ratio of the α-olefin monomer to the propylene monomer in the comonomer gas so that the α-olefin content in the resulting copolymer R is 10 to 55% by weight. Adjust so that
[0043]
On the other hand, the polypropylene-based composition uses a polymerization activity regulator of a catalyst such as carbon monoxide or hydrogen sulfide by adjusting the polymerization time (W_PP/ W_RC) Is ([η]_RC/ [Η]_PP) X (W_PP/ W_RC) = A predetermined range derived from 0.2 to 4.5 (about 0.17 to 7.5, preferably 1.0 to 4.0). Further, the copolymer R is [η]_RCIt is preferable to adjust by adding a molecular weight regulator such as hydrogen during the copolymerization so as to satisfy the requirement of = 6.5 dl / g or less.
[0044]
The polymerization method may be any of batch type, semi-continuous type or continuous type, but industrially preferred is a continuous type.
[0045]
After completion of the second polymerization step, the monomer can be removed from the polymerization system to obtain a granular polypropylene composition. A part of the obtained composition is subjected to measurement of intrinsic viscosity, measurement of ethylene content, and measurement of polymer yield per unit weight of catalyst.
[0046]
In the polypropylene composition used for the layer (A) in the present invention, known antioxidants, neutralizers, light stabilizers, ultraviolet absorbers, inorganics usually used for polyolefins, as long as the object of the present invention is not impaired. Additives such as a filler, an antiblocking agent, a lubricant, an antistatic agent, a metal deactivator, and a transparent nucleating agent can be blended.
[0047]
Examples of the antioxidant include phenolic antioxidants, phosphite antioxidants, and thio antioxidants, and examples of the neutralizer include higher fatty acid salts such as calcium stearate and zinc stearate. Examples of the light stabilizer and ultraviolet absorber include hindered amines, nickel complex compounds, benzotriazoles, and benzophenones. Examples of the inorganic filler and antiblocking agent include calcium carbonate, silica, hydrotalcite, zeolite, Examples of the lubricant include aluminum silicate, magnesium silicate, and the like. Examples of the lubricant include higher fatty acid amides such as stearic acid amide. Examples of the antistatic agent include fatty acid partial esters such as glycerin fatty acid monoester. Inactive agents include triazines, Osufon, epoxies, triazoles, hydrazides, etc. oxamides. Examples of possible such sorbitols and rosins and petroleum resins are exemplified such as alkyl-substituted benzylidene sorbitol as a transparent Kazo nucleating agent.
[0048]
As a method of blending the polypropylene-based composition and the above-mentioned additives, there is a method of blending with a usual blending device such as a mixer with a stirrer such as a Henschel mixer (trade name) or a propeller mixer and a ribbon blender or a tumbler mixer (dry blend). Further, a method of pelletizing the blend obtained by the above method using a normal single screw extruder or a twin screw extruder can be exemplified.
[0049]
The multilayer plastic sheet of the present invention typically has a three-layer structure of (A) / (B) / (A), and the multilayer plastic sheet has a polypropylene composition that constitutes the layer (A). It is a two-kind three-layer structure in which the products are the same, or a three-kind three-layer structure in which the polypropylene composition constituting the layer (A) is different. For example, (A) / (B) / (A) / (B) / (A) or (A) / (B) / (A) / (B) / (A) / (B) / (A) can also be configured.
[0050]
The thickness of the multilayer plastic sheet of the present invention is not particularly limited, but is preferably 0.07 to 5.0 mm, more preferably 0.2 to 3.0 mm from the viewpoint of moldability of the sheet. Further, the thickness of each layer of the multilayer plastic sheet is not particularly limited, but the layer (B) is 30 to 30% of the total thickness of the sheet in terms of sheet formability, high-frequency weldability, and optical properties. It is preferable to occupy 98%, and more preferably 70 to 90%.
[0051]
Examples of the method for producing the multilayer plastic sheet include a method for producing by a publicly known molding method (extrusion molding method, extrusion lamination method, compression molding method, cast molding method) generally used for polyolefin sheets. Among the known and publicly used molding methods, the extrusion molding method is preferred for the reason that productivity is good. Particularly preferably, extrusion using a T-die sheet forming machine equipped with an extruder, a feed block, a T die, a cooling roll, a guide roll, a take-up roll, an annealing roll, a trimming cutter, a masking, a regular cutting cutter, a stacker and the like. This is a manufacturing method by the T-die method.
Of course, the multilayer plastic sheet obtained by the present invention is usually used for industrial purposes, such as corona discharge treatment, flame treatment, plasma treatment, etc. for the purpose of imparting printability, paintability, metal deposition characteristics, etc. Needless to say, it is possible to perform surface treatment.
[0052]
When the multilayer plastic sheet is molded by the above publicly known method, the MFR of the polypropylene composition constituting the layer (A) is not particularly limited, but in terms of sheet moldability and finished sheet appearance, MFR ratio (MFR) of the polypropylene-based composition of the (A) layer and the ethylene-based copolymer of the (B) layer_A/ MFR_B) Is preferably 0.03 to 20, more preferably 0.5 to 2.0.
[0053]
【Example】
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
The polypropylene composition and ethylene copolymer used in Examples and Comparative Examples are described in detail below.
The physical property measuring method of the polypropylene-type composition used for the (A) layer is shown below. The α-olefin used for the crystalline P of the polypropylene composition and the copolymer R is ethylene.
[0054]
a) Intrinsic viscosity (unit: dl / g): measured using an automatic viscosity measuring apparatus (AVS2 type, manufactured by Mitsui Chemicals, Inc.) under a temperature condition of 135 ° C. using tetralin (tetrachloronaphthalene) as a solvent. .
b) Particle size (unit: μm) and uniformity of the titanium-containing solid catalyst component (I): Uniformity: The average particle size calculated from the particle size distribution measured using a master sizer (manufactured by MALVEREN) is used as the particle size, and 60% under sieve The value obtained by dividing the particle size by the particle size under 10% sieve was defined as the uniformity.
c) Propylene content of crystalline P and ethylene content of copolymer R (unit: wt%): Measured by infrared absorption spectroscopy.
d) Polymer yield per unit weight of catalyst: Mg content in the sample was measured by high frequency inductively coupled plasma emission spectroscopy (ICP method) and calculated from the obtained Mg content.
W_PPWas determined from {(crystalline P yield per catalyst unit weight) / (polypropylene composition yield per catalyst unit weight)} × 100.
W_RCIs 100-W_PPI asked more.
Here, (crystalline P yield per unit weight of catalyst) was determined by measuring the Mg content of crystalline P produced in the first polymerization step by ICP method.
The (polypropylene composition yield per catalyst unit weight) was determined by measuring the Mg content of the polypropylene composition obtained in the first polymerization step and the second polymerization step by the ICP method.
e) MFR_AWas extruded through a specified die at a temperature of 230 ° C. and a load of 21.18 N according to JIS K 7210, and the weight flowing out per unit time was determined.
[0055]
The polypropylene compositions used in the examples and comparative examples are shown below. Polypropylene compositions A-1 to 5 were obtained by the following production method.
1) Preparation of titanium-containing solid catalyst component
a) Titanium-containing solid catalyst component:
In a SUS autoclave purged with nitrogen, anhydrous MgCl₂95.3 g and 352 ml of dry EtOH (ethanol) were added and the mixture was heated to 105 ° C. with stirring to dissolve. After stirring for 1 hour, the solution was fed into a two-fluid spray nozzle with pressurized nitrogen (1.1 MPa) heated to 105 ° C. The flow rate of nitrogen gas was 38 liters / minute. Liquid nitrogen was introduced into the spray tower for cooling, and the temperature in the tower was maintained at -15 ° C. The product was collected in cold hexane introduced at the bottom of the column to obtain 256 g. From the analysis of the product, the composition of this support is the same MgCl as the starting solution.₂-6 EtOH.
[0056]
For use as a carrier, sieving was performed to obtain 205 g of a spherical carrier having a particle size of 45 to 212 μm. The resulting carrier was dried by aeration with nitrogen at a flow rate of 3 liters / minute at room temperature for 181 hours and the composition was MgCl.₂-A dry carrier of 1.7 EtOH was obtained.
[0057]
In a glass flask, 20 g of dry carrier, 160 ml of titanium tetrachloride and 240 ml of purified 1,2-dichloroethane were mixed, heated to 100 ° C. with stirring, added with 6.8 ml of diisobutyl phthalate, and further heated at 100 ° C. for 2 hours. Thereafter, the liquid phase part was removed by decantation, and 160 ml of titanium tetrachloride and 320 ml of purified 1,2-dichloroethane were added again. After heating and holding at 100 ° C. for 1 hour, the liquid phase portion was removed by decantation, washed with purified hexane, and dried to obtain a titanium-containing solid catalyst component: I-1. The obtained titanium-containing solid catalyst component (I) had an average particle size of 115 μm, and the analytical values thereof were Mg 19.5% by weight, Ti 1.6% by weight, Cl 59.0% by weight, diisobutyl phthalate. It was 5% by weight.
[0058]
2) Preactivation treatment of titanium-containing solid catalyst component
Saturated hydrocarbon solvent (CRYSTOL-52, manufactured by Esso Oil Co., Ltd.) with a kinematic viscosity at 40 ° C of 7.3 centistokes after replacing the SUS reactor with inclined blades with an internal volume of 15 liters with nitrogen gas After adding 8.3 liters, triethylaluminum 525 mmol, diisopropyldimethoxysilane 80 mmol, and 700 g of the titanium-containing solid catalyst component prepared in the previous section at room temperature, the mixture was heated to 40 ° C. and reacted at a propylene partial pressure of 0.15 MPa for 7 hours. Pre-activation treatment was performed. As a result of the analysis, 3.0 g of propylene was reacted per 1 g of the titanium-containing solid catalyst component.
[0059]
3) First polymerization step
In the flow sheet shown in FIG. 1, the titanium-containing solid subjected to the above preactivation treatment in a horizontal polymerization vessel 1 (length / diameter = L / D = 6, internal volume of 100 liters) equipped with a stirrer M having a stirring blade. The catalyst component was continuously fed at 0.5 g / hr, triethylaluminum as the organoaluminum compound, and diisopropyldimethoxysilane as the organosilicon compound. Liquid propylene is continuously supplied from the raw material propylene pipe 3 and a necessary amount of ethylene gas is supplied from the circulation pipe 2 so as to maintain the conditions of a reaction temperature of 70 ° C., a reaction pressure of 2.5 MPa, and a stirring speed of 40 rpm. In order to adjust the molecular weight, hydrogen gas was continuously supplied from the circulation pipe 2, and the intrinsic viscosity of the produced polymer was controlled by the hydrogen concentration in the gas phase of the reactor.
[0060]
The reaction heat was removed by the heat of vaporization of the raw material liquid propylene supplied from the raw material propylene pipe 3. The unreacted gas discharged from the polymerization reactor was cooled and condensed outside the reactor system through the unreacted gas pipe 4 and refluxed to the polymerization reactor 1.
[0061]
Crystalline P obtained in this polymerization vessel is continuously extracted from the polymerization vessel 1 through the pipe 5 so that the polymer retention level is 50% by volume of the reaction volume, and supplied to the polymerization vessel 10 in the second polymerization step. did. At this time, a part of the crystalline P is intermittently withdrawn from the polymer withdrawal pipe 5 to measure the intrinsic viscosity and propylene content, and to determine the crystalline P yield per unit weight of the catalyst. It used for the measurement.
[0062]
4) Second polymerization step
Crystalline P and ethylene gas from the first polymerization step are fed into the horizontal polymerization vessel 10 (L / D = 6, internal volume 100 liters) equipped with a stirrer M having a stirring blade from the activity inhibitor introduction pipe 7 and liquid propylene. Were continuously fed from the raw material propylene pipe 6 to copolymerize ethylene and propylene. The reaction conditions were such that the stirring rate was 40 rpm, the temperature was 60 ° C., the pressure was 2.1 MPa, and the ethylene content in the copolymer R was adjusted by the molar ratio of ethylene / propylene in the gas phase. In order to adjust the polymerization amount of the copolymer R, carbon monoxide was supplied as a polymerization activity inhibitor, and hydrogen gas was supplied from the activity inhibitor introduction pipe 7 in order to adjust the molecular weight of the copolymer R.
The reaction heat was removed by the vaporization heat of the raw material liquid propylene supplied from the raw material propylene pipe 6.
[0063]
The unreacted gas discharged from the polymerization vessel was cooled and condensed outside the reactor system through the unreacted gas pipe 8 and refluxed to the present copolymerization step. The polypropylene composition produced in the copolymerization step was extracted from the polymerizer 10 through the polymer extraction pipe 9 so that the retained level of the polymer was 50% by volume of the reaction volume.
[0064]
The production rate of the resulting polypropylene composition was 8-12 kg / hr.
The extracted polypropylene-based composition removes the monomer, and a part thereof is used for the determination of the ethylene content in the copolymer R by the intrinsic viscosity, infrared absorption spectrum method, and the yield of the polypropylene-based composition per unit weight of the catalyst. The ICP method was used to determine
[0065]
99.49% by weight of the polypropylene composition shown in Table 1, tetrakis [methylene (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane 0.03% by weight, tris (2,4-di-) t-butylphenyl) phosphite 0.08% by weight, calcium stearate 0.1% by weight, silka (anti-blocking agent) 0.2% by weight and oleic acid amide (lubricant) 0.1% by weight, Henschel mixer ( (Trade name), and then melt-kneaded at 230 ° C using a single screw extruder (65 mmφ diameter), pelletized, and a part of the pelletized polypropylene composition was MFR_AWe used for measurement. This pelletized polypropylene composition is abbreviated as A-1 to A-5 as shown in Table 1.
[0066]
[Table 1]

[0067]
As shown in Table 2, the pellets of the ethylene copolymer of the (B) layer used in Examples and Comparative Examples are abbreviated as follows.
B-1: The cohesive energy density is 68.7 cal / cm.^Three, MFR is 1.5 g / 10 min, crystal melting point is 90 ° C., Vicat softening point is 67 ° C., peak value of dielectric loss tangent is 1.6 × 10^-2An ethylene / vinyl acetate copolymer (Ultrasen 630 vinyl acetate (VA) content 15% by weight) manufactured by Tosoh Corporation is used.
B-2: Cohesive energy density is 70.7 cal / cm^Three, MFR 4.0 g / 10 min, crystal melting point 76 ° C., Vicat softening point 46 ° C., peak value of dielectric loss tangent 2.8 × 10^-2An ethylene / vinyl acetate copolymer (Ultrasen 634 VA content of 26% by weight) manufactured by Tosoh Corporation is used.
[0068]
[Table 2]

[0069]
Next, the evaluation method of the multilayer plastic sheet used by an Example and a comparative example is demonstrated.
tan δ (dielectric loss tangent): tan δ of the multilayer plastic sheet is determined by a mutual dielectric bridge method according to JIS K6911. It shows that it is easy to carry out dielectric heating within a high frequency electric field, so that the value of tan-delta is large.
Peel strength (unit: g / cm): Tensile test is performed with an Instron type tester on both ends of the seal part of the multilayer plastic sheet processed by high frequency welding. The larger the peel strength value, the stronger the adhesion.
Haze (transparency) (unit:%): According to ASTM D1003, the haze of the multilayer plastic sheet was measured and used as a standard for transparency. The smaller the value, the better the transparency.
Young's modulus (flexibility) (unit: MPa): According to ASTM D882, Young's modulus, which is the tensile elastic modulus of the multilayer plastic sheet, was measured and used as a reference for flexibility. The smaller the value, the more flexible.
Pencil hardness (scratch resistance): According to JIS K5400, a pencil scratch test of a multilayer plastic sheet was measured and used as a standard for scratch resistance. The harder the value indicated by the hardness of the pencil lead, the harder the surface of the multilayer plastic sheet, and the better the scratch resistance.
[0070]
(Examples-1 to 6 and Comparative Examples-1 to 4)
Table 2 shows a T-die and uses a combining adapter method, three types of five-layer extruder (single-screw extruder for intermediate layer with a diameter of 65 mmφ × 1, single-screw extruder for surface layer with a diameter of 40 mmφ × 2). Supply B-1 or B-2 to single-layer extruder for intermediate layer, and supply A-1, A-2, A-3, A-4 or A-5 shown in Table 1 to single-layer extruder for surface layer 2 types, 3 layers multi-layer coextrusion by melting at 230 ° C., and cooling and solidifying with an air knife and a cooling roll with a surface temperature of 50 ° C. A three-layer multilayer plastic sheet was obtained.
The obtained multilayer plastic sheet was evaluated, and the results are shown in Tables 3 and 4 below.
[0071]
[Table 3]

[0072]
[Table 4]

[0073]
From the above table, it can be seen that the examples of the present invention have higher tan δ and peel strength, lower haze and Young's modulus, and better transparency and flexibility than the comparative examples. In addition, the examples also ensure pencil hardness.
[0074]
【The invention's effect】
The multilayer plastic sheet of the present invention has an effect of having a large dielectric loss tangent (tan δ) as electrical characteristics and excellent high-frequency weld characteristics, as well as an excellent balance of transparency, flexibility and scratch resistance.
[Brief description of the drawings]
FIG. 1 shows a flow sheet of a continuous polymerization apparatus used in Examples.
[Explanation of symbols]
1, 10 Polymerizer
2 Circulation piping
3,6 Raw material propylene piping
4, 8 Unreacted gas piping
5, 9 Polymer extraction piping
7 Activity inhibitor introduction piping
M Stirrer

Claims (2)

(A) / (B) / (A) is a multilayer plastic sheet having a three-layer structure,
The layer (A) has a propylene content of 90 to 99% by weight and a crystalline propylene-α-olefin copolymer (hereinafter referred to as “crystalline P”) having a crystalline melting point of 160 ° C. or less, α- A propylene-α-olefin copolymer (hereinafter referred to as “copolymer R”) having an olefin content of 10 to 55% by weight,
[Η] _RC = 6.5 dl / g or less;
[Η] _RC / [η] _PP = 0.6 to 1.2; and ([η] _RC / [η] _PP ) × (W _PP / W _RC ) = 0.2 to 4.5 A polypropylene composition,
([Η] _RC : Intrinsic viscosity of copolymer R, [η] _PP : Intrinsic viscosity of crystalline P, W _PP : Weight% of crystalline P with respect to polypropylene composition, W _RC : Copolymer with respect to polypropylene composition % By weight of polymer R)
The layer (B) has a cohesive energy density of 60 to 90 cal / cm ³ , a melt flow rate of 1.0 to 15.0 g / 10 min, a crystal melting point of 50 to 120 ° C., a Vicat softening point of 100 ° C. or less, and a dielectric loss tangent. A multilayer plastic sheet for high-frequency weld processing , comprising an ethylene copolymer having a peak value of 5.0 × 10 ⁻³ (100 kHz) or more. Ethylene copolymers include ethylene / vinyl acetate copolymer, ethylene / methyl methacrylate copolymer, ethylene / glycidyl methacrylate copolymer, ethylene / glycidyl methacrylate / vinyl acetate copolymer, and ethylene / ethyl acrylate / maleic anhydride. 2. The multilayer plastic sheet for high frequency welding according to claim 1 , wherein the multilayer plastic sheet is selected from copolymers.

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