JP2008201911A - Masking tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent physical properties deterioration of an adhesive layer and formation of adhesive deposits in a masking tape occasionally exposed to a high-temperature environment. <P>SOLUTION: The masking tape is obtained by forming a removable adhesive layer on one side of a polyvinyl chloride substrate. Here, the polyvinyl chloride substrate comprises polyvinyl chloride, polyester adipate plasticizer and thermal stabilizers, provided that the thermal stabilizers comprise calcium stearate, zinc stearate and a hydrotalcite compound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a masking tape or sheet for coating, and more particularly to a masking tape or sheet for coating that is useful when different paints are applied at the time of coating various workpieces. In addition, although this invention relates to a tape and a sheet | seat, in the following description, a tape is represented and demonstrated for convenience.

  Masking tape is used to apply paints when painting various articles (hereinafter also referred to as “workpieces”). In particular, a base material using soft polyvinyl chloride having excellent flexibility is frequently used as a base material of a masking tape used for a painting operation on a complicated curved surface.

  The workpiece may be exposed to a high temperature of 160 ° C. or higher during the coating operation or subsequent drying and baking. In this case, the masking tape is also exposed to a high temperature. Especially in the case of a masking tape based on soft polyvinyl chloride, the plasticizer and stabilizer in the substrate bleed out, and the adhesive layer The physical properties of the product may be impaired. In addition, when the plasticizer or stabilizer bleeds out to the substrate surface, the adhesiveness between the adhesive layer and the substrate decreases, and when the masking tape is peeled from the workpiece, the adhesive layer is transferred to the workpiece, In some cases, so-called glue residue was caused and the workpiece was contaminated.

  Therefore, the heat resistance is required for the base material of the masking tape at the time of painting including the process in which the workpiece is exposed to high temperature as described above. For this reason, vinyl chloride containing a lead-based heat stabilizer has been used as a base material for a masking tape used in this type of high temperature coating.

  However, the use of lead compounds is not preferred from the viewpoints of environmental protection and occupational health. For this reason, various adhesive tapes based on a polyvinyl chloride sheet using a lead-free stabilizer have been proposed.

  Patent Document 1 discloses an adhesive tape using a base material composed of polyvinyl chloride, a fatty acid metal salt such as zinc stearate or calcium stearate as a stabilizer, and magnesium hydroxide and / or magnesium oxide. . Patent Document 1 describes that a hydrotalcite-based compound or the like may be added to a base material in order to capture dehydrochlorination from polyvinyl chloride (Patent Document 1, paragraph 0019). Furthermore, in patent document 1, in addition to a phthalate ester, adipic acid polyester etc. are illustrated as a plasticizer (patent document 1, paragraph 0024). However, in Patent Document 1, the only plasticizer that is actually used is dioctyl phthalate (DOP), and no investigation has been made on other plasticizers, particularly adipic acid polyester. The pressure-sensitive adhesive sheet of Patent Document 1 is intended to prevent bleed out of the stabilizer under a heating environment, but the assumed operating temperature range is from room temperature to 70 ° C., and 160 ° C. as described above. Use at these temperatures is not considered.

  In an example of Patent Document 1, a high-temperature and high-humidity environment of an adhesive sheet using a substrate containing polyvinyl chloride, DOP, a hydrotalcite compound, zinc stearate, calcium stearate, and magnesium hydroxide and / or magnesium oxide Underneath stabilizer bleed has been investigated, but in some examples bleed has been observed at 70 ° C. For this reason, in the base material described in the Example of patent document 1, if it exposes to the environment of 160 degreeC or more, it will be thought that a bleed | flash becomes more remarkable.

  Moreover, in the comparative example 1 of patent document 1, the bleeding of the stabilizer in the high-temperature, high-humidity environment of the adhesive sheet using the base material which consists of polyvinyl chloride, DOP, a hydrotalcite compound, zinc stearate, and calcium stearate is carried out. Although being investigated, bleeding has already been confirmed at 35 ° C.

When a stabilizer or the like bleeds out from the base material, not only the physical properties of the pressure-sensitive adhesive layer are impaired, but also due to the stabilizer bleed out between the base material and the pressure-sensitive adhesive layer, the adhesive layer and the base material Adhesion is lowered, and the pressure-sensitive adhesive layer is transferred to the workpiece, causing adhesive residue and contaminating the workpiece.
Japanese Patent Laid-Open No. 11-228917

  The present invention is intended to solve the problems associated with the prior art as described above, and is an environmentally friendly masking tape having heat resistance equivalent to that of a masking tape using a vinyl chloride base material containing a lead-based stabilizer. Is to provide. That is, an object of the present invention is to prevent deterioration of physical properties of an adhesive layer and generation of adhesive residue in a masking tape that may be exposed to a high temperature environment.

  The gist of the present invention aimed at solving such problems is as follows.

(1) A masking tape in which a re-peelable pressure-sensitive adhesive layer is provided on one surface of a polyvinyl chloride base material,
The masking tape in which the said polyvinyl chloride base material contains a polyvinyl chloride, an adipic acid polyester type plasticizer, and a calcium stearate, a zinc stearate, and a hydrotalcite type compound as a heat stabilizer.

(2) The masking tape according to (1), wherein the weight average molecular weight of the adipic acid polyester plasticizer is 500 to 2200.

(3) The masking tape according to (1) or (2), wherein the re-peelable pressure-sensitive adhesive layer comprises an acrylic emulsion-type pressure-sensitive adhesive.

  According to the masking tape of the present invention, there is no deterioration in physical properties of the pressure-sensitive adhesive layer even when it is exposed to a high-temperature environment after being attached to a work, and the occurrence of adhesive residue can be prevented.

  Hereinafter, the present invention will be described more specifically.

  The masking tape according to the present invention comprises a polyvinyl chloride base material and a re-peelable pressure-sensitive adhesive layer formed thereon. Here, the polyvinyl chloride base material contains polyvinyl chloride as a main component, adipic acid polyester as a plasticizer, and calcium stearate, zinc stearate, and a hydrotalcite compound as heat stabilizers.

  As polyvinyl chloride as the main component, various polyvinyl chlorides widely used as base materials for various adhesive tapes are used without particular limitation, but from the viewpoint of good processability, polymerization of suspension polymerization Polyvinyl chloride having a degree of preferably 800 to 1500, more preferably 1000 to 1300 is particularly preferably used.

  The adipic acid polyester used as the plasticizer is a condensation reaction product of adipic acid and a dihydric alcohol, and examples thereof include those condensed with a monohydric alcohol as a terminal terminating component. As these dihydric alcohols, diols having 6 to 9, preferably 7 to 9 carbon atoms of an alkylene group are preferred. The alkylene group may be linear or branched. Specific examples of such dihydric alcohols include ethylene glycol, propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, and 1,5-pentanediol. , 3-methyl-1,5-pentanediol, 1,6-hexanediol and the like.

  Examples of the monovalent alcohol as the terminal termination component include normal octyl alcohol, 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, decyl alcohol and the like.

  As the adipic acid polyester, an adipic acid polyester having a weight average molecular weight of 500 to 2200, preferably 800 to 2000 is suitably used. If the molecular weight of the adipic acid polyester is too low, water resistance and plasticizer bleeding may occur. On the other hand, if the molecular weight is too high, the vinyl chloride compound at the film forming temperature becomes highly viscous and the film It may be difficult to form or the plasticizing effect as a substrate for use as a masking tape may be reduced. The molecular weight of the adipic acid polyester is measured by gel permeation chromatography (GPC).

  Adipic acid polyester may be used individually by 1 type, and may use 2 or more types together. The adipic acid polyester is preferably used in a proportion of 5 to 50 parts by weight, more preferably 20 to 45 parts by weight, based on 100 parts by weight of the polyvinyl chloride. If the amount of adipic acid polyester is too small, the flexibility of the substrate may be insufficient. On the other hand, if the amount is too large, the stability during film formation may be reduced. .

  The polyvinyl chloride base material further contains calcium stearate, zinc stearate and a hydrotalcite compound as a heat stabilizer. In addition, in this invention, a required effect is show | played by using said 3 types of heat stabilizer together, Even if any one lacks, the effect of this invention is not show | played.

  Conventionally known hydrotalcite compounds can be used. Specifically, Japanese Patent Nos. 2501820, 2519277, 2712898, 3167853, Japanese Patent Publication No. 06-051826, Japanese Patent Laid-Open No. 09-118810, Japanese Patent Laid-Open No. 10-158360, Japanese Patent Laid-Open No. 11-240937, Japanese Patent Laid-Open No. 11-310766. No., JP-A No. 2000-159520, JP-A No. 2000-230110, JP-A No. 2002-08056, etc. may be used.

In particular, the general formula: Mg _x Al _y (OH) _{2x + 3y + 2z} (CO ₃ ) ₂ .mH ₂ O (x, y, z are 0 <y / x ≦ 1, 0 ≦ z / y <1. And m is an integer.) Is preferably used from the viewpoint of easy availability and the like.

  The heat stabilizer is a total of calcium stearate, zinc stearate and hydrotalcite compound, and is preferably 1 to 3 parts by weight, more preferably 1.2 to 2 parts per 100 parts by weight of the polyvinyl chloride. Used in a proportion of 0 parts by weight. If the blending amount of the heat stabilizer is too small, there is a risk of thermal degradation, while if the blending amount is too large, the stabilizer may bleed.

  The calcium stearate is preferably used in a proportion of 0.05 to 1.0 part by weight, more preferably 0.1 to 0.7 part by weight, based on 100 parts by weight of the polyvinyl chloride. Preferably 0.1 to 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight, and the hydrotalcite compound is preferably 0.3 to 1.5 parts by weight, Preferably it is used in a proportion of 0.5 to 1.0 parts by weight. By using calcium stearate, zinc stearate and hydrotalcite compound in the above proportions, the effect of the present invention is more remarkably exhibited.

  In addition to the above, the polyvinyl chloride-based substrate may contain a filler, a pigment, an elastomer, and the like as long as the object of the present invention is not impaired.

  The polyvinyl chloride base material is obtained by kneading the above components and film-forming the kneaded product. Although there is no restriction | limiting in particular about the thickness of a polyvinyl chloride base material, Usually, 10-200 micrometers, Preferably it selects in the range of 20-150 micrometers.

  In the present invention, for the purpose of improving the adhesion of the polyvinyl chloride base material to the re-peelable pressure-sensitive adhesive layer provided thereon, a physical or chemical method such as an oxidation method or an unevenness method is optionally used. Surface treatment can be performed. Examples of the oxidation method include corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment and the like, and examples of the unevenness method include a sand blast method and a solvent treatment method. . These surface treatment methods are appropriately selected depending on the type of the film, but generally, the corona discharge treatment method is preferably used from the viewpoints of effects and operability.

  In the masking tape of the present invention, a re-peelable pressure-sensitive adhesive layer is provided on one surface of the vinyl chloride base material. There is no restriction | limiting in particular as an adhesive used for the said releasable adhesive layer, From the things conventionally conventionally used as an adhesive for a masking tape, arbitrary things can be selected suitably and can be used. For example, acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, polyurethane-based pressure-sensitive adhesives, and polyester-based pressure-sensitive adhesives can be used. Among these, acrylic pressure-sensitive adhesives are generally used.

  Examples of the acrylic pressure-sensitive adhesive include, as main components, (meth) acrylic acid ester homopolymers, copolymers containing two or more (meth) acrylic acid ester units, and (meth) acrylic acid esters and other functionalities. What contains at least 1 sort (s) chosen from the copolymer with a monomer is used. Examples of the (meth) acrylate ester include butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, and (meth) acrylic. Acid nonyl, decyl (meth) acrylate, and the like can be mentioned. Examples of functional monomers include hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate, and amide groups such as (meth) acrylamide and dimethyl (meth) acrylamide. Examples thereof include monomers and monomers containing carboxylic acid groups such as (meth) acrylic acid. These may be either solvent-based or emulsion-based. In particular, an acrylic emulsion-type pressure-sensitive adhesive is preferably used from the viewpoints of versatility and environmental conservation.

  These pressure-sensitive adhesives can be blended with a crosslinking agent, a tackifier, an antioxidant, a filler and the like as desired. The thickness of the pressure-sensitive adhesive layer is usually selected in the range of 10 to 70 μm, preferably 20 to 50 μm.

  From the viewpoint of handleability, the masking tape of the present invention is preferably covered with a release sheet on the surface of the pressure-sensitive adhesive layer prior to its use. Therefore, the re-peelable pressure-sensitive adhesive layer may be directly applied to one side of the polyvinyl chloride base material to provide the pressure-sensitive adhesive layer, but the pressure-sensitive adhesive is applied on the release sheet to provide the pressure-sensitive adhesive layer. Thereafter, it is preferable to apply this to a polyvinyl chloride base material, transfer the pressure-sensitive adhesive layer, and leave the release sheet as it is.

  Examples of the release sheet include paper base materials such as glassine paper, coated paper, and high-quality paper, laminated paper obtained by laminating a thermoplastic resin such as polyethylene on these paper base materials, or polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate. There are no particular restrictions on the thickness of this release sheet, although there are no particular restrictions on the thickness of the release sheet, such as a polyester film such as a polyolefin film such as polypropylene or polyethylene, and a release film such as a silicone resin. It is about 200 μm.

(Example)
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

In the following Examples and Comparative Examples, polyvinyl chloride having a polymerization degree of about 1000 and adipic acid polyester plasticizer having a weight average molecular weight of about 1200 were used in preparing the base materials. Calcium stearate, zinc stearate, hydrotalcite compounds,
Commercially available tribasic lead sulfate and barium stearate were used.

  First, each component as shown in the table was blended in each proportion to prepare a mixture that was a film raw material. The blending ratio in the table indicates parts by weight. Thereafter, a 100 μm-thick film was formed by a calendar method using the mixture to obtain a substrate.

Further, silicone processing was performed on glassine paper (60 g / m ² ) to prepare a release sheet having a thickness of 70 μm. Emulsion-based re-peelable pressure-sensitive adhesive (Mitsui Chemicals MT-TACK-CR 5322ER) was applied on the release sheet, dried, a 20 μm-thick pressure-sensitive adhesive layer was formed, and the substrate was bonded to obtain a masking tape. .

  In this way, the prepared masking tape is affixed to a stainless steel plate under normal temperature conditions, heated to 160 ° C., 170 ° C., and 190 ° C., held for 20 minutes or 40 minutes, returned to normal temperature, and has adhesive strength and removability. confirmed.

  The adhesive strength measurement method was based on the adhesive strength measurement method of JIS Z 0237. These results are shown in the table below.

Moreover, the stainless steel plate surface after masking tape peeling was observed visually, and the presence or absence of adhesive residue was evaluated. If the area of a stainless steel plate surface 25 cm ² per glue has Zangi is less than 1 cm ² A, if 1 to 5 cm ² B, if it exceeds 5 cm ² was evaluated as C.

As in Examples 1, 2, and 3, by using calcium stearate, zinc stearate and a hydrotalcite compound as stabilizers, the physical properties of the pressure-sensitive adhesive layer are not deteriorated in a high temperature environment without containing heavy metals. There was obtained a masking tape that could prevent the occurrence of adhesive residue.

Claims (3)

A masking tape provided with a re-peelable pressure-sensitive adhesive layer on one surface of a polyvinyl chloride base material,
The masking tape in which the said polyvinyl chloride base material contains a polyvinyl chloride, an adipic acid polyester type plasticizer, and a calcium stearate, a zinc stearate, and a hydrotalcite type compound as a heat stabilizer.   The masking tape according to claim 1, wherein the adipic acid polyester plasticizer has a weight average molecular weight of 500 to 2200.   The masking tape according to claim 1, wherein the re-peelable pressure-sensitive adhesive layer is made of an acrylic emulsion-type pressure-sensitive adhesive.