JP2003049136A - Masking tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a masking tape suitably usable for masking the non-plated portions in making a plating treatment of a lead frame metallic plate or the like mounted on an electronic part, having both high elastic modulus and dimensional accuracy of the substrate layer and presenting high application accuracy even with narrow wiring pattern width. SOLUTION: This masking tape is such that an adhesive layer is formed on one side of the substrate layer made from a polypropylene-based resin composition comprising 100 pts.wt. of a polypropylene-based resin and 0.1-100 pts.wt. of a layered silicate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a masking tape having a substrate layer with high dimensional accuracy and excellent attachment accuracy, and more particularly to a masking tape for plating.

[0002]

2. Description of the Related Art Conventionally, a masking tape used for masking (protecting) a non-plated portion when a lead frame metal plate or the like provided in an electronic component is plated, is disclosed in, for example, JP-A-7-3490. As disclosed in JP-A No. 11-172488 and Japanese Patent Laid-Open No. 11-172488, a masking tape for plating is generally formed by forming an adhesive layer on one surface of a base material layer made of a polyolefin resin such as polyethylene or polypropylene. Is used for.

However, in recent years, with the progress of miniaturization of electronic devices such as transistors, the width of the wiring pattern of integrated parts such as LSI has become narrower. Therefore, especially in the production of striped plated strips, it is required to improve the dimensional accuracy of the plated portion and the non-plated portion.

In general, in the step of attaching the masking tape for plating, the tape winding body is unrolled and fed out, slitted according to the dimensional accuracy of the non-plated portion, and then attached to the frame strip. During that time, tension is applied to the tape, so elongation occurs due to the creep phenomenon immediately after slitting and before being attached to the frame strip,
The slit width may shrink, or the slit width may fluctuate due to the tension fluctuation. If such a displacement of the plated portion and the non-plated portion occurs, even a portion that does not require plating may be plated, or conversely, a portion that does not require plating may not be plated. There is a problem that a short circuit occurs between the lead frame and a product in which the lead frame metal plate is post-processed is likely to malfunction.

In order to prevent such problems from occurring, it is necessary to improve the dimensional accuracy of the masking tape, and the base material layer forming the masking tape has low compliance, that is, high elastic modulus. Is required.

[0006]

SUMMARY OF THE INVENTION In view of the above situation, it is an object of the present invention to provide a masking tape having a high dimensional accuracy of a base material layer and an excellent bonding accuracy, particularly a masking tape for plating.

[0007]

According to the present invention, a pressure-sensitive adhesive layer is provided on one side of a base material layer made of a polypropylene resin composition containing 1 to 100 parts by weight of a layered silicate with respect to 100 parts by weight of a polypropylene resin. It is a masking tape formed. The present invention is described in detail below.

The masking tape of the present invention comprises a base material layer and an adhesive layer. The base material layer is made of a polypropylene resin composition containing a polypropylene resin and a layered silicate.

The polypropylene-based resin is not particularly limited, and examples thereof include homopolymers of propylene and α-other than propylene and propylene copolymerizable with the propylene.
Examples thereof include copolymers with olefins, propylene-ethylene random copolymers and block copolymers, and polypropylene alloy resins. These polypropylene resins may be used alone or in combination of two or more kinds.

The α-olefin other than propylene is not particularly limited, and examples thereof include ethylene, 1-butene,
1-hexene, 4-methyl-1-pentene, 1-octene and the like can be mentioned. These α-olefins other than propylene may be used alone or in combination of two or more kinds.

The above polypropylene alloy resin means a resin containing a polypropylene resin as a main component and an elastomer component (rubber component) finely dispersed therein.
The method of finely dispersing the elastomer component (rubber component) in the polypropylene resin as the main component is not particularly limited. For example, the elastomer component (rubber component) is added to the polypropylene resin that has been heated and melted to uniformly disperse it. A method of finely dispersing by kneading or adding an elastomer component (rubber component) to the polymerization system of polypropylene resin to simultaneously polymerize the polypropylene resin and finely disperse the elastomer component (rubber component) at the same time. A method of performing the same can be mentioned.

The above-mentioned layered silicate means a silicate mineral having an exchangeable metal cation between layers. The layered silicate is not particularly limited, for example, montmorillonite,
Examples thereof include smectite-based clay minerals such as saponite, hectorite, beidellite, stevensite, nontronite, vermiculite, halloysite, and swelling mica. Among them, montmorillonite and / or swelling mica is preferably used. The layered silicate may be a natural product or a synthetic product. Also,
These layered silicates may be used alone or 2
More than one kind may be used in combination.

As the layered silicate, it is preferable to use smectites or swelling mica having a large shape anisotropy effect defined by the following formula. By using the layered silicate having a large shape anisotropy effect, the mechanical strength of the base material layer made of the polypropylene resin composition becomes more excellent. Shape anisotropy effect = area of crystal surface (A) / area of crystal surface (B) In the formula, the crystal surface (A) means a layer surface, and the crystal surface (B) means a layer side surface.

The shape of the layered silicate is not particularly limited, but the preferable lower limit of the average length is 0.01 μm.
m, the upper limit is 3 μm, and the preferable lower limit of the thickness is 0.001 μm.
m, the upper limit is 1 μm, and the preferable lower limit of the aspect ratio is 2
0, the upper limit is 500, the more preferable lower limit of the average length is 0.05 μm, the upper limit is 2 μm, the more preferable lower limit of the thickness is 0.01 μm, the upper limit is 0.5 μm, and the more preferable lower limit of the aspect ratio is 50, the upper limit. Is 200.

The exchangeable metal cations existing between the layers of the layered silicate are metal ions such as sodium and calcium existing on the crystal surface of the layered silicate, and these metal ions are cationic substances. Since it has a cation exchangeability with, it is possible to insert (intercalate) various substances having a cationic property between the crystal layers of the layered silicate.

The cation exchange capacity of the layered silicate is not particularly limited, but the preferred lower limit is 50 mm equivalent / 100 g and the upper limit is 200 mm equivalent / 100 g. If the amount is less than 50 mm equivalent / 100 g, the amount of the cationic substance intercalated between the crystal layers of the layered silicate by cation exchange may be small, and the crystal layers may not be sufficiently depolarized. Equivalent /
If it exceeds 100 g, the bonding force between the crystal layers of the layered silicate may be too strong, and the crystal flakes may be difficult to peel off.

It is preferable that the above-mentioned layered silicate is made hydrophobic by previously exchanging cations between the layers with a cationic surfactant. By making the layers of the layered silicate hydrophobic in advance, the affinity between the layered silicate and the polypropylene resin is increased, and the layered silicate can be more finely dispersed in the polypropylene resin more uniformly.

The cationic surfactant is not particularly limited, and examples thereof include a quaternary ammonium salt and a quaternary phosphonium salt. Among them, a quaternary ammonium salt having an alkyl chain having 6 or more carbon atoms (alkylammonium salt having 6 or more carbon atoms) is preferably used because it can sufficiently depolarize the crystal layers of the layered silicate.

The quaternary ammonium salt is not particularly limited, and examples thereof include lauryl trimethyl ammonium salt,
Stearyl trimethyl ammonium salt, distearyl dimethyl ammonium salt, di-hardened tallow dimethyl ammonium salt, distearyl dibenzyl ammonium salt, N-polyoxyethylene-N-lauryl-N, N-dimethyl ammonium salt and the like can be mentioned. These quaternary ammonium salts may be used alone or in combination of two or more kinds.

The quaternary phosphonium salt is not particularly limited, and examples thereof include dodecyltriphenylphosphonium salt, methyltriphenylphosphonium salt, lauryltrimethylphosphonium salt, stearyltrimethylphosphonium salt, distearyldimethylphosphonium salt, distearyldibenzylphosphonium salt. Salt etc. are mentioned. These quaternary phosphonium salts may be used alone or in combination of two or more kinds.

The layered silicate used in the present invention can be improved in dispersibility in a polypropylene resin by a chemical treatment as described above. The chemical treatment is not limited to the cation exchange method using a cationic surfactant (hereinafter, also referred to as the chemical modification (1) method), and can be carried out by various chemical treatment methods shown below, for example. . The layered silicate whose dispersibility in the polypropylene resin is improved by the various chemical treatment methods described below, including the chemical modification (1) method, is also referred to as “organized layered silicate” hereinafter.

(2) Chemical modification A functional group capable of chemically bonding a hydroxyl group present on the crystal surface of the organically modified layered silicate chemically treated by the method (1), or chemically without the chemical bond. A method of chemically treating with a compound having one or more functional groups having a high affinity at a molecular end (hereinafter, also referred to as a chemical modification (2) method).

(3) Chemical Modification A functional group capable of chemically bonding a hydroxyl group present on the crystal surface of the organically modified layered silicate chemically treated by the method (1), or chemically without the chemical bond. A method of chemically treating with a compound having one or more functional groups and reactive functional groups having high affinity at the molecular end (hereinafter,
Chemical modification (3) method).

(4) Method of chemically modifying the crystal surface of the organically modified layered silicate chemically treated by the method of chemical modification (1) (hereinafter, also referred to as the method of chemical modification (4)) ).

(5) Chemical modification In the method (4), a chemical treatment is carried out with a compound having one or more reactive functional groups in addition to the anion site in the molecular chain of the compound having anionic surface activity (hereinafter referred to as chemical modification. (5) Also called the law).

(6) The organically modified layered silicate chemically treated by any one of the above-mentioned chemical modification (1) to chemical modification (5) is further used, for example, a maleic anhydride-modified polyolefin resin. Examples thereof include a method using a composition to which a polymer having a functional group capable of reacting with a layered silicate is added (hereinafter, also referred to as a chemical modification (6) method). These chemical modification methods may be used alone or in combination of two or more.

In the above-mentioned chemical modification (2), the functional group capable of chemically bonding with a hydroxyl group or the functional group having a large chemical affinity even if it is not chemically bonded is not particularly limited, and examples thereof include an alkoxy group and an epoxy group. Group, carboxyl group including dibasic acid anhydride, hydroxyl group, isocyanate group,
Examples thereof include functional groups such as aldehyde groups and other functional groups having high chemical affinity with hydroxyl groups.

The compound having a functional group capable of chemically bonding with the hydroxyl group or a functional group having a large chemical affinity even if not chemically bonded is not particularly limited, and examples thereof include silanes having the functional groups exemplified above. Examples thereof include compounds, titanate compounds, glycidyl compounds, carboxylic acids, alcohols and the like. These compounds may be used alone or in combination of two or more kinds.

The silane compound is not particularly limited, and examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy).
Silane, γ-aminopropyltrimethoxysilane, γ-
Aminopropylmethyldimethoxysilane, γ-aminopropyldimethylmethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyldimethylethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, trimethylmethoxy Silane, hexyltrimethoxysilane, hexyltriethoxysilane, N-β- (aminoethyl) γ-aminopropyltrimethoxysilane,
N-β- (aminoethyl) γ-aminopropyltriethoxysilane, N-β- (aminoethyl) γ-aminopropylmethyldimethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane , Γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane and the like. These silane compounds may be used alone or 2
More than one kind may be used in combination.

The above chemical modification (4) method and chemical modification (5)
In the method, the compound having anionic surface activity and / or the compound having anionic surface activity and having at least one reactive functional group other than the anion site in the molecular chain is a layered silicic acid by ionic interaction. Any compound may be used as long as it can chemically treat a salt, for example, sodium laurate, sodium stearate,
Examples thereof include sodium oleate, higher alcohol sulfate ester salt, secondary higher alcohol sulfate ester salt, unsaturated alcohol sulfate ester salt and the like. These compounds may be used alone or in combination of two or more kinds.

Examples of the chemical modification (6) include a method using a composition containing a polymer having a functional group capable of reacting with a layered silicate such as a maleic anhydride-modified polyolefin resin as a dispersant. To be This is necessary to disperse the layered silicate by mixing a dispersant having a site having a high affinity with the layered silicate and a site having a high affinity with the polypropylene resin, which is the base resin, to enhance the compatibility of the two. It is a method to reduce the energy.

As the dispersant, maleic anhydride-modified polyolefin-based oligomers are preferably used.
Above all, an AB type diblock polymer or diblock oligomer having different properties at both ends is preferably used. It is efficient that both ends have different properties (high affinity for each of layered silicate / polypropylene resin) and are of A (layered silicate affinity site) -B (polypropylene resin affinity site) type. In addition, a suitable dispersion effect can be obtained because the respective affinity is easily exhibited. Also,
In addition to these, examples of the dispersant include a polar group-containing ethylene-vinyl acetate copolymer (hereinafter also referred to as EVA) and a polar group-containing ethylene-ethyl acrylate copolymer (hereinafter also referred to as EEA). Polyolefin resins having polar groups such as ethylene-methyl acrylate copolymer (hereinafter, also referred to as EMA) are also suitable. Polyolefin resins having these polar groups are superior in terms of cost, and resins having various polar group contents can be obtained relatively easily, so that the optimum tape physical properties required can be appropriately selected and further manufactured. This is advantageous for designing a resin having optimum melting characteristics. As a method for obtaining a highly dispersed state by using the AB type dispersant or the polyolefin resin having a polar group as a dispersant, a method of melt-kneading a polypropylene resin and a layered silicate together with the dispersant in an extruder. However, it is not particularly limited.

The above-mentioned layered silicate has an average interlayer distance of (001) plane of 3 nm or more measured by the wide-angle X-ray diffraction measurement method in the base material layer, and part or all of which is dispersed in 5 layers or less. It is preferable that the average interlayer distance is 6 nm or more, and a part or all of the average interlayer distance is 5 nm or more.
That is, it is dispersed below the layer. The average interlaminar distance of the layered silicate means the average interlaminar distance in the case of forming a layer of fine flaky crystals of the layered silicate, and is obtained by X-ray diffraction peak and transmission electron microscope photography, that is, a wide angle. It can be measured by X-ray diffractometry. Further, the observation of the dispersed state of the layered silicate was carried out by a transmission electron microscope at 50,000-
Of the layered silicate layered aggregates (X) that can be observed in a certain area by observing at a magnification of 100,000, the number of layered aggregates (Y) dispersed in 5 layers or less is counted and calculated by the following formula. It can be calculated. Ratio (%) of layered silicate dispersed in 5 layers or less = (Y
/ X) x 100

When the layered molecules of the layered silicate, which is originally a laminate of several tens of layers, are separated and dispersed, the interaction between the layered crystal flakes of the layered silicate weakens to a negligible extent, and the crystal flakes form. Stabilizes by maintaining a certain distance in polypropylene resin and becoming a finely dispersed state. As a result, the layered silicate has a large average interlayer distance between the crystal flakes and is dispersion-stabilized, and significantly contributes to the improvement of the elastic modulus of the polypropylene resin composition and the base material layer. That is, the polypropylene resin composition and the base material layer in which the crystal thin layer of the layered silicate is dispersed with the average interlayer distance of 3 nm or more, preferably 6 nm or more, exhibit an excellent elastic modulus.

Further, part or all of the layered silicate is dispersed in five layers or less, which means that part or all of the layered molecules of the layered silicate, which is essentially a laminated body of several tens of layers. This means that they are peeled off and widely dispersed, which also means that the interaction between the crystal flakes of the layered silicate is weakened, and the same effect as described above can be obtained.

In particular, when the average interlayer distance between the crystal flakes of the layered silicate is 3 nm or more, preferably 6 nm or more,
A polypropylene-based resin composition obtained by blending and dispersing a layered silicate in a polypropylene-based resin and a base material layer comprising the same exhibit remarkably excellent various properties such as mechanical strength and heat resistance. Further, when the average interlayer distance between the crystal flaky layers of the layered silicate is 3 nm or more, preferably 6 nm or more, the layered silicate crystal flakes separate into layers,
Since the interaction between the crystal flakes of the layered silicate is almost negligible, there is an advantage that the dispersed state of the crystal flakes constituting the layered silicate in the polypropylene resin progresses toward crushing stabilization.

The fact that part or all of the layered silicate is dispersed in 5 layers or less means that 10% or more of the layered silicate is dispersed in 5 layers or less. Is preferable, and more preferably 20% or more of the layered silicate is dispersed in 5 layers or less.

It is preferable that the number of laminated layered silicates is divided into 5 layers or less, and thereby the same effect as described above can be obtained, but more preferably, it is divided into 3 layers or less. It is particularly preferable that the thin film is formed into a single layer.

In the polypropylene resin composition, the average interlayer distance between the crystal flakes of the layered silicate is 3 nm.
As described above, preferably 6 nm or more, and a part or all of the layered silicate is dispersed in 5 layers or less, that is,
If the layered silicate is highly dispersed in the polypropylene resin, the interfacial area between the polypropylene resin and the layered silicate increases.

When the interfacial area between the polypropylene resin and the layered silicate is increased, the degree of restraint of the polypropylene resin on the surface of the layered silicate is increased, and the mechanical strength such as elastic modulus is improved. Further, when the degree of restraint of the polypropylene resin on the surface of the layered silicate is increased, the melt viscosity of the polypropylene resin composition is increased and the moldability is also improved.

The lower limit of the blending amount of the layered silicate in the polypropylene resin composition is 0.1 part by weight, and the upper limit is 10 parts by weight with respect to 100 parts by weight of the polypropylene resin.
0 parts by weight. When it is less than 0.1 parts by weight, the elastic modulus of the polypropylene resin composition and the base material layer is not sufficiently improved, and when it exceeds 100 parts by weight, the melt viscosity of the polypropylene resin composition becomes too high, Molding into the base material layer becomes difficult and the cost becomes high. A preferred upper limit is 20 parts by weight.

The method for dispersing the layered silicate in the polypropylene resin is not particularly limited. For example, a method using the organically modified layered silicate described above; the polypropylene resin and the layered silicate are kneaded by a conventional method. After that, a method of foaming; a method of using a dispersant and the like can be mentioned. By using these dispersion methods, the layered silicate can be more uniformly and finely dispersed in the polypropylene resin.

A method of foaming after kneading the polypropylene resin and the layered silicate by a conventional method will be described below. This method is a method of foaming a polypropylene resin using a foaming agent and converting the foaming energy into the dispersion energy of the layered silicate. The foaming agent is not particularly limited, and examples thereof include a gaseous foaming agent, an easily volatile liquid foaming agent, and a heat decomposable solid foaming agent.
These foaming agents may be used alone or in combination of two or more kinds.

The specific method for dispersing the layered silicate in the polypropylene type resin by foaming the polypropylene type resin in the presence of the layered silicate is not particularly limited. A composition comprising 100 parts by weight and 0.1 to 100 parts by weight of a layered silicate is impregnated with a gaseous foaming agent under high pressure, or an easily volatile liquid foaming agent is kneaded, and then the gaseous foaming is performed. Dispersing method by forming a foam by evaporating a foaming agent or a readily volatile liquid foaming agent in the composition; a heat decomposable solid foaming agent is previously contained between layers of the layered silicate, and its thermal decomposition is performed. Examples include a dispersion method in which the solid foaming agent is decomposed by heating to form a foamed structure.

In the polypropylene resin composition, in addition to the polypropylene resin and the layered silicate which are essential components, a filler, a softening agent, and a plasticizer may be added, if necessary, within a range not hindering the achievement of the object of the present invention. , One or more of various additives such as a lubricant, a flame retardant, an antistatic agent, an antifogging agent, a coloring agent, an antioxidant (antiaging agent), a heat stabilizer, a light stabilizer, and an ultraviolet absorber. It may be blended.

The method for preparing the polypropylene-based resin composition is not particularly limited. For example, a predetermined amount of the polypropylene-based resin and the layered silicate and one or more kinds of various additives to be blended as necessary. Each predetermined amount of
A method of directly blending and kneading at room temperature or under heating (direct kneading method); a master batch is prepared by previously blending a predetermined amount of layered silicate to a part of a predetermined amount of polypropylene resin and kneading. A method (masterbatch method) of kneading the masterbatch, the balance of the polypropylene-based resin, and one or more predetermined amounts of various additives to be blended as required at room temperature or under heating Can be mentioned.

When the above masterbatch method is used, the compounding amount of the layered silicate of the masterbatch is not particularly limited, but a preferable lower limit is 1 part by weight and an upper limit is 500 with respect to 100 parts by weight of the polypropylene resin. Parts by weight. If it is less than 1 part by weight, the convenience as a masterbatch capable of diluting to an arbitrary concentration may be lost, and if it exceeds 500 parts by weight, the dispersibility of the masterbatch itself and, in particular, a predetermined composition due to a polypropylene resin The dispersibility of the layered silicate when diluted to a certain amount may be poor. A more preferred lower limit is 5 parts by weight and an upper limit is 300 parts by weight.

The specific method for preparing the polypropylene resin composition by the above direct kneading method or masterbatch method is not particularly limited, and for example, a kneading machine such as an extruder, two rolls, three rolls or Banbury mixer can be used. Using a method of uniformly kneading each predetermined amount of polypropylene-based resin and layered silicate and one or more predetermined amounts of various additives to be blended as necessary at room temperature or under heating, A polypropylene resin and a layered silicate and one or more kinds of various additives to be blended as necessary,
Examples thereof include a method of uniformly kneading in a solvent in which these can be dissolved or dispersed.

The method for molding the above-mentioned substrate layer is not particularly limited. For example, a polypropylene resin composition prepared in advance is melt-kneaded and extruded by an extruder, and then extruded into a film (using a T-die or circular die). A method of molding into a sheet shape; a method of dissolving or dispersing the polypropylene resin composition in a solvent such as an organic solvent and then molding into a film shape (sheet shape) by a cast method, and the like.

The thickness of the base material layer is not particularly limited, but the preferred lower limit is 30 μm and the upper limit is 100 μm.
Is. If it is less than 30 μm, the elastic modulus and mechanical strength may be insufficient, and if it exceeds 100 μm, the outer diameter of the long base material layer wound body becomes too large, and a large unwinder space is required. It may happen or the cost may increase.
A more preferable lower limit is 30 μm and an upper limit is 60 μm.
The base material layer may have a single layer structure or a multilayer structure of two or more layers.

Further, the surface of the base material layer is previously subjected to treatments such as corona discharge treatment, plasma discharge treatment, and primer (undercoating agent) coating in order to enhance the adhesion to the adhesive layer. Is also good.

The pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include rubber-based (elastomer-based) such as natural rubber-based pressure-sensitive adhesives and synthetic rubber-based pressure-sensitive adhesives.
Adhesives: various adhesives generally used for masking tapes such as acrylic resin adhesives, polyvinyl ether resin adhesives, silicone resin adhesives and other synthetic resin adhesives. These adhesives may be used alone or in combination of two or more.

The form of the above-mentioned pressure-sensitive adhesive is not particularly limited, and examples thereof include solvent-type pressure-sensitive adhesives, non-water emulsion-type pressure-sensitive adhesives, emulsion-type pressure-sensitive adhesives, dispersion-type pressure-sensitive adhesives, hot melt-type pressure-sensitive adhesives, ultraviolet rays and the like. It may be in any form such as a monomer-type or oligomer-type pressure-sensitive adhesive that can be cured (polymerized) with energy rays. The pressure-sensitive adhesive may be a non-cross-linking pressure-sensitive adhesive, a cross-linking pressure-sensitive adhesive, a one-component pressure-sensitive adhesive, or a multi-liquid pressure-sensitive adhesive of two or more liquids. May be

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but the preferred lower limit is 1 μm in thickness of solid content, and the upper limit is 20 μm. If it is less than 1 μm, the tackiness or tackiness of the masking tape of the present invention may be insufficient, and if it exceeds 20 μm, the removability after use of the masking tape may deteriorate.

The method for producing the masking tape of the present invention is not particularly limited, and for example, an adhesive is applied to a predetermined surface (one surface) of the above base material layer using an ordinary coating machine such as a roll coater. After the steps such as drying, cooling, irradiation with active energy rays, etc. as necessary, the pressure-sensitive adhesive layer is formed, and if necessary, the release treated surface of the release material such as release paper (release paper) or release film. Is laminated on the pressure-sensitive adhesive layer (direct coating method); after the pressure-sensitive adhesive layer is formed on the release-treated surface of the release material by the same method as described above, this pressure-sensitive adhesive layer is laminated on the predetermined surface of the base material layer. do it,
A method of transferring the pressure-sensitive adhesive layer to a predetermined surface of the base material layer (transfer method); two layers of the polypropylene resin composition for the base material layer and the pressure-sensitive adhesive for the pressure-sensitive adhesive layer are coextruded to form the base material layer. A method (two-layer coextrusion method) of simultaneously performing molding and formation of the pressure-sensitive adhesive layer at the same time can be used. Among them, the two-layer coextrusion method is preferable because it is excellent in productivity.

The masking tape of the present invention is JIS K
7113 "Plastic tensile test method", tensile stress at 5% strain is 39.2 N / mm
² or more, or the tensile elastic modulus is 784.0 N / m
It is preferably m ² or more. Tensile stress is 39.2N
/ Mm ² or a tensile elastic modulus of 784.0
If it is less than N / mm ² , the dimensional accuracy becomes insufficient,
The pasting accuracy may decrease.

The masking tape of the present invention can exhibit an extremely high elastic modulus because the layered silicate is highly dispersed on the nanometer scale in the base material layer, and has an extremely high dimensional stability. If the masking tape of the present invention is used as a masking tape for plating that masks (protects) the non-plated portion when the lead frame metal plate or the like provided in the electronic component is plated, the positions of the plated portion and the non-plated portion No deviation occurs. Therefore, the masking tape of the present invention is particularly suitable as a masking tape for plating used for masking during soldering.

Further, since the masking tape of the present invention does not contain a halogen-based component, there is no fear that a large amount of halogen-based gas will be generated during combustion even when incinerated at the time of disposal. It does not corrode the equipment or have any adverse effects on the human body. Therefore, it can be said that it is advantageous in terms of total cost because it can be processed by general waste equipment.

[0059]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 A polypropylene resin (J215W manufactured by Grand Polymer Co., density:
0.91 g / cm ³ , MFR: 9 g / 10 min (230
90 ° C.) 90 parts by weight, maleic anhydride-modified polyethylene oligomer (manufactured by Japan Polyolefin Co., ER403A) 5
5 parts by weight, and 5 parts by weight of swellable fluorine mica (Somasif MAE-100 manufactured by Cope Chemical Co., Ltd.) that has been subjected to a hydrophobic treatment with distearyl dimethyl quaternary ammonium salt are fed and melt-kneaded at a set temperature of 190 ° C. And extruded into a strand shape, and the extruded strand was pelletized by a pelletizer to prepare pellets of a polypropylene resin composition.

Further, 100 parts by weight of a hydrogenated product of styrene-butadiene-styrene block copolymer (SEBS, Kraton G1657 manufactured by Kraton Polymer Japan Co., Ltd.) and an alicyclic hydrogenated petroleum resin (Arcon manufactured by Arakawa Chemical Industry Co., Ltd.) P-125) 50 parts by weight was uniformly kneaded to prepare an adhesive.

The polypropylene resin composition pellets and the pressure-sensitive adhesive thus obtained were molded into a film (sheet) by a two-layer coextrusion method, and the thickness of the base material layer was 50 μm.
A masking tape having a pressure-sensitive adhesive layer having a thickness of 10 μm was produced.

Example 2 94 parts by weight of a polypropylene resin composition (J215W, manufactured by Grand Polymer Co., Ltd.) for a base material layer, 5 parts by weight of diblock type oligomers (CB-OM12, manufactured by Kuraray Co., Ltd.) on both ends were used. Parts and 1 part by weight of swellable fluorine mica (Somasif MAE-100, manufactured by Coop Chemical Co., Ltd.) that has been subjected to a hydrophobic treatment with distearyl dimethyl quaternary ammonium salt, and in the same manner as in Example 1. And the thickness of the base material layer is 40μ
m, and a masking tape having an adhesive layer thickness of 10 μm was produced.

(Example 3) 75 parts by weight of a polypropylene resin composition (J215W, manufactured by Grand Polymer Co., Ltd.) and 5 parts by weight of diblock type oligomer (CB-OM12, manufactured by Kuraray Co., Ltd.) were used for the base material layer. Parts and 20 parts by weight of swellable fluorine mica (Somasif MAE-100, manufactured by Coop Chemical Co., Ltd.) that has been subjected to a hydrophobizing treatment with distearyl dimethyl quaternary ammonium salt, and in the same manner as in Example 1. And the thickness of the base material layer is 40
A masking tape having a thickness of 10 μm and a pressure-sensitive adhesive layer having a thickness of 10 μm was produced.

(Example 4) An ethylene-vinyl acetate copolymer (manufactured by Mitsui DuPont, Evaflex EV2) was prepared by using a diblock type oligomer (CB-OM12 manufactured by Kuraray Co., Ltd.) at both ends.
60), except that in the same manner as in Example 2,
The thickness of the base material layer is 40 μm, and the thickness of the adhesive layer is 10 μm.
A masking tape having a thickness of μm was produced.

Example 5 The same hydrophobizing treatment was applied in place of the swelling fluorine mica (Somasif MAE-100, manufactured by Coop Chemical Co.) which was hydrophobized with distearyldimethyl quaternary ammonium salt. Montmorillonite (Southern Clay Products Co., Clayton HY)
A masking tape having a substrate layer thickness of 40 μm and a pressure-sensitive adhesive layer thickness of 10 μm was produced in the same manner as in Example 2 except for the above.

(Comparative Example 1) A polypropylene resin composition for a base material layer was used as a swellable fluorine mica (Somasif MAE-100 manufactured by Coop Chemical Co.) and a maleic anhydride modified polyethylene oligomer (ER manufactured by Nippon Polyolefin Co., Ltd., ER).
A masking tape having a substrate layer thickness of 50 μm and an adhesive layer thickness of 10 μm was produced in the same manner as in Example 1 except that 403A) was not blended.

Comparative Example 2 A polypropylene resin composition for a base material layer was prepared by using 99.95 parts by weight of a polypropylene resin (J215W manufactured by Grand Polymer Co., Ltd.) and a maleic anhydride-modified polyethylene oligomer (ER403A manufactured by Nippon Polyolefin Co., Ltd.). 5 parts by weight and a swellable fluorine mica that has been hydrophobized with distearyldimethyl quaternary ammonium salt (Somasif MAE-manufactured by Corp Chemical)
100) A masking tape having a base material layer having a thickness of 40 μm and an adhesive layer having a thickness of 10 μm was prepared in the same manner as in Example 1 except that the amount was 0.05 part by weight.

Regarding the masking tapes obtained in Examples 1 to 5 and Comparative Examples 1 and 2, the average interlayer distance of the layered silicate in the base material layer, the ratio and density of the layered silicate dispersed in 5 layers or less. Was measured by the following method. Further, the tensile elastic modulus and the tensile stress at 5% strain of these masking tapes were measured. The results are shown in Table 1.

(Measurement of Average Layer Distance of Layered Silicate) Using an X-ray diffractometer (RINT1100, manufactured by Rigaku Corporation), the diffraction peak 2θ obtained by diffraction of the laminated surface of the layered silicate in the base material layer Is measured, and the (001) plane spacing (d) of the layered silicate is calculated by the following black diffraction formula,
The obtained d was taken as the average interlayer distance (nm). λ = 2 dsin θ In the formula, λ is 1.54, d represents the interplanar spacing of the layered silicate, and θ represents the diffraction angle.

(Ratio of Layered Silicate Dispersed in Five Layers or Less) The base material layer was cut out with a diamond cutter, and a transmission electron microscope (JEM-1200EXI manufactured by JEOL Ltd.) was used.
I) The number of dispersed layers of the layered silicate aggregate per unit area was measured by a photograph, and the ratio of dispersed layers of 5 or less was calculated.

(Measurement of Density) The density (g / cm ³ ) of the base material layer was measured by a conventional method.

(Measurement of Tensile Elastic Modulus and Tensile Stress at 5% Strain) A masking tape was cut into a sample having a width of 10 mm, and a gripping interval (distance between chucks) 40 mm was measured according to JIS K 7113. Tensile speed 500m
The tensile stress and the tensile elastic modulus at 5% strain were measured under the condition of / min.

[0074]

[Table 1]

From Table 1, in each of the masking tapes of Examples 1 to 5, the layered silicate was highly and uniformly dispersed in a fine dispersion, and the high tensile elastic modulus and the tensile stress at 5% strain were observed. It was found that it has excellent dimensional accuracy.
On the other hand, it was found that the required mechanical properties and dimensional stability were not obtained in Comparative Example 1 in which the layered silicate was not blended and Comparative Example 2 in which the amount of the layered silicate was small.

[0076]

The masking tape of the present invention contains a specific amount of a layered silicate with respect to a specific amount of a polypropylene resin, and a polypropylene resin in which the layered silicate is finely and uniformly dispersed in the polypropylene resin. Since the base material layer made of the composition and having high dimensional accuracy is used, excellent sticking accuracy is exhibited. Therefore, the masking tape of the present invention is particularly suitable for use as a masking tape for plating used for masking a non-plated portion when plating a lead frame metal plate or the like provided in an electronic component.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C25D 5/02 C25D 5/02 D (72) Inventor Hideyuki Takahashi 2-1 Hyakusan, Shimamoto-cho, Mishima-gun, Osaka Prefecture Sekisui Chemical Co., Ltd. (72) Inventor Koichi Shibayama 2-1 Hyakuyama, Shimamoto-cho, Mishima-gun, Osaka Prefecture 2-1 F-Term inside Sekisui Chemical Co., Ltd. (reference) 4F100 AA03A AC03A AC05A AK03A AL05A AR00B BA02 CB05B DE10A GB90 JA20 JB10A JK02 JK04 JL13B 4J004 AA05 AA08 AA10 AA11 AB01 AB03 AB06 CA04 FA04 FA05 4J040 CA001 DD051 DF001 EK031 JA02 JA03 JA09 JA12 JA13 JB01 JB09 MA11 PA23 PA32 4K024 AB08 BA01 BB13 BC01 FA10 GA16

Claims (6)

[Claims] 1. A pressure-sensitive adhesive layer is formed on one side of a base material layer made of a polypropylene resin composition containing 0.1 to 100 parts by weight of a layered silicate with respect to 100 parts by weight of a polypropylene resin. Characteristic masking tape. 2. The layered silicate is montmorillonite and / or
Alternatively, the masking tape according to claim 1, which is a swelling mica. 3. The masking tape according to claim 1, wherein the layered silicate contains an alkylammonium ion having 6 or more carbon atoms. 4. The layered silicate has an average interlayer distance of 3 in the (001) plane measured by a wide-angle X-ray diffraction measurement method in a base material layer.
The masking tape according to claim 1, 2 or 3, wherein the masking tape has a thickness of not less than nm and a part or all of which is dispersed in 5 layers or less. 5. The tensile stress at 5% strain measured according to JIS K 7113 is 39.2 N / mm ² or more, or the tensile elastic modulus is 784.0 N / mm ² or more. The masking tape according to claim 1, 2, 3, or 4. 6. The masking tape according to claim 1, which is a masking tape for plating.