JP2002256233A - Adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a repeelable adhesive sheet having a moderate flexibility, a low adhesion when peeled and a small residue of an adhesive and capable of being treated with simple incineration equipment. SOLUTION: This adhesive sheet is prepared by laminating an adhesive layer on a polyolefin-based base material layer and has 9.8-49 N/15 mm tensile stress of the polyolefin-based base material layer at 2% modules, 10-40 μm thickness of the adhesive layer and >=80% gel fraction of the adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive sheet suitably used as an outdoor or indoor advertising sticker, a display sticker, a decorative sticker, or the like.
The pressure-sensitive adhesive sheet of the present invention includes a pressure-sensitive adhesive film, and the pressure-sensitive adhesive sheet used for the above-mentioned applications is generally called a marking film in many cases.

More specifically, the present invention can be applied to an advertising signboard after printing or other decoration, and can be easily peeled off after use without leaving adhesive on an adherend. The present invention relates to a removable pressure-sensitive adhesive sheet that can be incinerated and disposed of without any problem.

[0003]

2. Description of the Related Art In general, a marking film is made of a soft vinyl chloride resin film as a base layer, and the base layer is kneaded with a pigment according to the application and purpose, and colored.
After printing and painting, apply an appropriate pressure-sensitive adhesive (pressure-sensitive adhesive) to one side of the base material layer according to the application and purpose, and form a pressure-sensitive adhesive layer. It is configured by laminating a release material layer such as release paper or release film for the purpose of protecting the adhesive layer.In use, the release adhesive layer is peeled off and the exposed adhesive layer is applied to a predetermined portion of the adherend. Used by pasting.

Advertisement stickers used for signboards, advertising towers, shutters, show windows, etc .; outdoor stripe stickers used for vehicles such as automobiles and motorcycles and motor boats; and traffic signs. , Road signs, display stickers used for information boards and the like.

[0005] Among them, a re-peelable marking film, which is applied on a decorative signboard and peeled and discarded after being used for a short period of time, has attracted attention. That is, due to recent corporate circumstances, it is often necessary to simultaneously deploy new CIs to branches, sales offices, stores, and the like scattered throughout the country. However, it is practically impossible to simultaneously change the signboards of a large number of branches, business offices, stores, and the like on the same day.

Therefore, a method is generally adopted in which a new CI logo is constructed by the day before the change, and a sheet decorated with the old CI is pasted thereon. By this method, C
New CI easily by peeling off the sheet the night before I change
It is possible to change to For this reason, in the re-peelable marking film, it has a moderate flexibility to be attached to the signboard, a low adhesive strength so that it can be easily peeled off, and the property that no adhesive remains on the actual signboard as an adherend, Especially needed.

[0007] Similar to conventional outdoor and indoor marking films, the conventional removable marking film is made of a vinyl chloride resin film as a base material. Therefore, when incinerated and discarded, hydrogen chloride gas or dioxin is used. Therefore, there is a problem that the treatment cannot be performed by a simple incineration facility, and the durability of the simple incineration facility is reduced. Therefore, recently, a demand for a low environmental load type marking film that can be processed by a simple incineration facility has been increasing.

For example, JP-A-8-157780 proposes a marking film in which a polyolefin resin film is used as a base layer and an adhesive layer is laminated on the base layer. It is described that recycling is easy because incineration and disposal are possible with such a configuration.

[0009] However, although the above-mentioned marking film uses an olefin resin film for the base material layer, its quality is not designed with respect to removability, and the peeling work is inefficient due to the high adhesive strength at the time of peeling. In addition, adhesive residue on the adherend due to the high adhesive strength is a concern. In addition, there is also a problem in workability because it lacks appropriate flexibility for attaching the removable marking film.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional removable marking film, and has an appropriate flexibility required for a removable adhesive sheet, a low adhesive strength at the time of peeling, and a low adhesive strength. An object of the present invention is to provide a re-peelable pressure-sensitive adhesive sheet which has adhesive residue and can be processed by a simple incineration facility.

[0011]

Hereinafter, the present invention will be described in more detail. In order to achieve the above object, an invention according to claim 1 is an adhesive sheet in which an adhesive layer is laminated on a polyolefin-based substrate layer, wherein the polyolefin-based substrate layer has a tensile stress of 9% at a 2% modulus. 0.8-49N
/ 15 mm, a pressure-sensitive adhesive layer having a thickness of 10 to 40 μm, and a gel fraction of the pressure-sensitive adhesive of 80% or more.

Hereinafter, the present invention will be described in more detail. As the type of polyolefin resin used for the polyolefin substrate of the removable pressure-sensitive adhesive sheet of the present invention, olefins, among them, refers to a homopolymer or a copolymer having ethylene or propylene as a main structural unit, Specific examples of the resin constituting (a) include, in addition to polyethylene and polypropylene, copolymers of ethylene and propylene, and mixtures thereof. Among them, a polyolefin resin having high heat resistance is preferable because a printing layer is required to be laminated, and a polypropylene resin is particularly preferable. When flexibility is particularly important, a polyethylene resin is preferable. However, if the flexibility is excessive, the removability is reduced. Therefore, a mixture of a polypropylene resin and a polyethylene resin is preferable.

The thickness of the substrate layer is usually 50 to 300 μm, preferably 80 to 150 μm. The stress of the base material layer is 9.8 to 49 N / 15 mm at a modulus of 2%.
Is required, and preferably 19.6 to 29.4 N / 15.
mm. If the thickness is less than 9.8 N / 15 mm, the adhesive strength at the time of peeling the sheet increases, and the peeling workability is remarkably reduced.
If it exceeds 49 N / 15 mm, the film itself becomes too hard, which makes it difficult to perform the work, and it is not possible to follow even the slight unevenness of the signboard, resulting in a poor finished appearance.

The polyolefin-based substrate of the present invention may contain other general-purpose additives (lubricant, nucleating agent, antistatic agent, antiblocking agent, antioxidant, light stabilizer, ultraviolet absorber, inorganic filler, organic filler, There is no problem in blending a flexibility-imparting elastomer or the like. In the present invention, it is preferable to blend a pigment such as titanium oxide in order to impart hiding power to the polyolefin-based substrate layer. It is preferable that the pigments are mixed by using a masterbatch or the like, which is used as a general-purpose technique to enhance the dispersibility of the pigment in the resin. The polyolefin-based substrate of the present invention can be formed into a film by a T-die method, an inflation method, or the like as conventionally used after blending the above-mentioned additives with the polyolefin-based resin.

There is no problem even if the base material layer has a multilayer structure of two or more layers for adjusting the modulus value and the like. Since the formed substrate layer film generally has a low surface tension,
It is desirable to improve the adhesion of the printing layer and the pressure-sensitive adhesive layer by corona treatment and surface modification by coating with a primer or the like.

The pressure-sensitive adhesive used in the pressure-sensitive adhesive layer in the present invention may be either an acrylic resin-based or rubber-based pressure-sensitive adhesive. However, since the marking film is assumed to be used outdoors, Acrylics having high weather resistance are preferably used.

As a main component of the acrylic pressure-sensitive adhesive, a polymer of a (meth) acrylate monomer is used. For example, a (meth) acrylate of an alcohol having an alkyl group having 1 to 12 carbon atoms is preferably used. Is a (meth) acrylate polymer having an alkyl group having 4 to 12 carbon atoms, and more specifically, (meth)
N-butyl acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth)
Homopolymers or copolymers such as n-octyl acrylate, isononyl (meth) acrylate, and lauryl (meth) acrylate can be given.

From the viewpoint of the balance between tackiness and cohesiveness,
A glass transition temperature (Tg) of a homopolymer is mainly composed of a (meth) acrylate having a temperature of -50 ° C or less, and a (meth) acrylate
A copolymer using a (meth) acrylate of a lower alcohol such as methyl acrylate or ethyl (meth) acrylate is used. Further, in addition to these vinyl monomers, monomers copolymerizable with them may be copolymerized. As monomers, (meth) acrylic acid,
Carboxyl group-containing monomers such as maleic acid, fumaric acid, and itaconic acid or anhydrides thereof, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl acrylate, polyoxyethylene (meth) acrylate, polyoxypropylene (meth) acrylate And hydroxyl-containing monomers such as caprolactone-modified (meth) acrylate.

The pressure-sensitive adhesive of the present invention may be a solvent-type acrylic pressure-sensitive adhesive polymerized in a solvent or an emulsion-type pressure-sensitive adhesive polymerized in water. Alternatively, a block polymerization type pressure-sensitive adhesive obtained by irradiating the monomer mixture with ultraviolet light may be used.

The pressure-sensitive adhesive layer has a thickness of 10 to 40 μm. When the thickness is less than 10 μm, the peel strength at the time of outdoor use becomes a problem because the adhesive strength is too low, and when it exceeds 40 μm, the peeling workability at the time of peeling becomes extremely poor because the adhesive strength is too strong. Also, the gel fraction (resin crosslink density) of the pressure-sensitive adhesive
Is required to be 80% or more. If it is less than 80%, the adhesion to the adherend over time increases, and the adhesive strength increases, so that the peeling workability at the time of peeling becomes extremely poor.

The cross-linking agent slightly varies depending on the content of the functional group monomer.
When hydroxyethyl methacrylate is blended, an isocyanate-based crosslinking agent is used. However, other appropriate crosslinking agents can be used.

In general, a marking film is prepared by applying a pressure-sensitive adhesive to a release material in advance by a quantitative coating method using a comma coater or a reverse coater, and then drying by heating.
It is manufactured by laminating with a substrate.

Further, the release material for the marking film of the present invention is not particularly limited, and for example, a silicone-coated release paper can be used.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to the following Examples unless the gist of the present invention is obtained. (Example 1) In accordance with the composition shown in Table 1, a polyolefin-based substrate was formed into a film having a thickness of 300 µm by a T-die method, and a double-sided corona treatment (42 dyne / cm) was performed in-line.
Was used as a substrate layer.

On the other hand, the pressure-sensitive adhesive layer is made of an acrylic pressure-sensitive adhesive “NM”.
-1 "(adhesive manufactured by Sekisui Chemical Co., Ltd.) and the isocyanate-based curing agent" Coronate 2094 "(Nippon Polyurethane Co., Ltd.)
After mixing and stirring, dry thickness 20 with a comma coater.
It was obtained by coating a silicone-coated release paper to a thickness of μm and forming a film. A marking film was obtained. The pressure-sensitive adhesive layer formed on the release paper was laminated and laminated on the olefin base film to obtain a target marking sheet.

(Examples 2 and 3) A substrate was prepared according to the resin composition and thickness shown in Table 1, and the paste thickness and
A marking sheet was obtained in the same manner as in Example 1 except that the glue gel fraction was used. (Comparative Examples 1 to 3) According to the resin composition and thickness described in Table 1,
A marking sheet was obtained in the same manner as in Example 1 except that a substrate was prepared and the paste thickness and the paste gel fraction shown in Table 1 were used.

[0027]

[Table 1]

(Measurement Method of Physical Properties) <2% Modulus> After preparing a sample of 15 mm × 250 mm, after curing at 23 ° C. and 65% RH for 1 hour or more, a tensile test was performed at a chuck distance of 100 mm and a pulling speed of 200 mm / min. The stress at 2% elongation of the sample was measured.

<Gel Fraction> After drying the adhesive with release paper,
The film was sandwiched with release paper and cured in a 40 ° C. gear oven for 3 days. After curing, the pressure-sensitive adhesive was collected in a sample bottle, and the weight of the pressure-sensitive adhesive was measured with a precision balance (A), followed by stirring with an ethyl acetate solution at room temperature for 24 hours to sufficiently swell the pressure-sensitive adhesive. Thereafter, the adhesive was filtered into a 200-mesh wire mesh simple dish and dried as it was in a gear oven at 110 ° C. for 2 hours. After drying, the dried pressure-sensitive adhesive weight (B) was measured after filtration with a precision balance. Finally, the pressure-sensitive adhesive gel fraction was calculated by the following equation. Gel fraction (%) = (B) / (A) × 100

(Evaluation of practical use) Regarding the marking film obtained by the above method, workability, peelability, adhesive residue,
Table 1 shows the results of the incineration possibility. Each determination method is as follows.

<Workability> A marking film “Tac Paint” manufactured by Sekisui Chemical Co., Ltd. is adhered to one side of a 300 × 300 mm aluminum plate, and the marking film of the present invention is applied to a work jig “Squeegee” from above. And stuck. The tooling condition at that time was evaluated on the following scale.・ ・ ・: Moderate flexibility, no problem in normal construction. ×: The flexibility of the film was too large or, on the contrary, too hard, giving a sense of incongruity and a great problem in normal construction.

<Releasability> The marking film of the present invention was peeled off by hand from the sample itself used in the above "Evaluation of workability", and the peeling workability at that time was evaluated.・ ・ ・: Since the peeling force was low, the sheet could be easily peeled off, and there was no practical problem. X: The peeling force was heavy, and workability was a major problem.

<Adhesive Remaining Property> The state of adhesive remaining on the tack paint after peeling of the marking film of the present invention in the above “evaluation of peelability” was evaluated.・ ・ ・: No glue was left on the tack paint. ×: Glue remained in part or a considerable area of tack paint.

<Judgment of possible incineration> Each of the marking films prepared by the above-described method was sampled in a square of 5 cm, burned in a closed container, and gas was further collected in a syringe, and hydrogen chloride and chlorine were sampled by a gas chromatograph. The gas was qualitatively analyzed.・ ・ ・: No hydrogen chloride or hydrogen gas was detected. X: Hydrogen chloride and hydrogen gas were detected.

[0035]

The olefin resin-based peelable pressure-sensitive adhesive sheet of the present invention has a moderate flexibility, so that it has the same handling properties as a conventional vinyl chloride-based peelable marking film, and has a low tackiness when peeled. Because of its power, it can exhibit the same releasability and adhesive residue as a conventional vinyl chloride re-peelable marking film, and after its use, unlike conventional products, does not require landfill disposal and is easy to incinerate Since it can be incinerated and disposed of in equipment, it is extremely useful in this field as a product with low environmental load.

Claims (3)

[Claims] 1. A pressure-sensitive adhesive sheet comprising a polyolefin-based substrate layer and a pressure-sensitive adhesive layer laminated thereon, wherein the polyolefin-based substrate layer has a tensile stress of 9.8 to 4 at a 2% modulus.
9N / 15mm, and the thickness of the pressure-sensitive adhesive layer is 10 to 40μ.
m, and the gel fraction of the pressure-sensitive adhesive is 80% or more. 2. The pressure-sensitive adhesive sheet according to claim 1, wherein the polyolefin-based substrate layer is a polypropylene resin layer. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the polyolefin-based substrate layer is a resin layer composed of a mixture of polypropylene and low-density polyethylene.