JP2001323229A - Base film for adhesive tape and adhesive tape using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain both a substrate film for an adhesive tape having excellent heat resistance, flexibility, followingness to a curved surface, tensile strength, openability, blocking resistance and adhesive coating suitability and an adhesive tape using the same. SOLUTION: This substrate film for an adhesive tape is characterized in that the substrate film is a film comprising a polypropylene-based resin as a main component and the creep compliance of the film at 90 deg.C is 10-70 GPa-1. The adhesive tape is obtained by using the substrate film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to heat resistance, flexibility,
The present invention relates to a base film for a pressure-sensitive adhesive tape having excellent followability to a curved surface, tensile strength, opening property, blocking resistance, and suitability for pressure-sensitive adhesive coating, and a pressure-sensitive adhesive tape using the same.

[0002]

2. Description of the Related Art Conventionally, as a material used for a base material for an adhesive tape, a soft vinyl chloride resin is exemplified. Soft vinyl chloride resins are used for various applications because of their excellent flexibility, weather resistance, transparency and the like. However, soft vinyl chloride resin containing chlorine like soft vinyl chloride resin may generate harmful substances such as hydrogen chloride gas and dioxin that are highly toxic to humans during incineration, and pollute the environment. It is said to be causing this. Therefore, in recent years, there has been a tendency in society to avoid using a soft vinyl chloride resin. In addition, the plasticizer added to the soft vinyl chloride resin migrates to the film surface or a material that comes into contact with the plasticizer, thereby deteriorating the appearance or emitting odor.

As an alternative to the soft vinyl chloride resin, a polyolefin resin has been studied, for example, polyethylene, polypropylene, etc., and a method of using a polyolefin resin film having irregularities on one side as a base film for an adhesive tape (particularly, JP-A-10-298504), a method of using a stretched polypropylene film or a film in which polypropylene and another plastic film are laminated as a base film for an adhesive tape (Japanese Patent Laid-Open No.
-199835).

[0004] When polyethylene is used as a base material for an adhesive tape, it is excellent in flexibility and transparency, but is inferior in heat resistance.
The film itself may be stretched, or may undergo heat shrinkage after the drying process. Therefore, when providing a pressure-sensitive adhesive layer on polyethylene, separately apply the pressure-sensitive adhesive to release paper, etc.
A method of transferring the pressure-sensitive adhesive layer is adopted. Therefore, an extra process and release paper are required, and the cost is higher than a case where the adhesive is directly applied to the film itself and dried. Furthermore, the operating temperature range of the pressure-sensitive adhesive tape is limited by the lack of heat resistance of polyethylene itself.

On the other hand, when polypropylene is used as a base material for an adhesive tape, since the heat resistance is excellent, it is possible to apply and dry the adhesive on the film itself, but the film itself has high rigidity and is inferior in flexibility. Therefore, the ability to follow a curved surface is poor, and it is difficult to attach an adhesive tape to a projection or the like.

[0006] Instead of using polyethylene or polypropylene alone, a method of imparting flexibility by adding a rubber such as an ethylene-propylene copolymer or an ethylene-butene copolymer to these polymers (Japanese Patent Laid-Open No. 7-90091) ,
Japanese Patent Application Laid-Open No. Hei 7-276589) is disclosed.
However, in these methods, the self-adhesion of ethylene-propylene copolymer, ethylene-butene copolymer, etc., results in poor opening during production unless an antiblocking agent is added, and winding after film formation. , The blocking phenomenon easily occurs.

[0007] In addition to the above-mentioned method, by laminating a resin layer having a thickness of 0.5 to 20 µm selected from acrylic resin, polyamide resin, vinyl resin, nitrocellulose resin and urethane resin on a polyethylene film, There is disclosed a method of reducing deformation of a film due to heating in a drying step at the time of coating of an agent (JP-A-10-7996). However, this method requires a step of laminating a resin layer for imparting heat resistance to the polyethylene layer.

[0008]

For the reasons described above, the present invention is excellent in flexibility, curved surface followability, tensile strength, and opening property at the time of film formation, which are equal to or higher than that of soft vinyl chloride resin. It does not cause a blocking phenomenon in winding after film formation, there is no need to laminate a resin layer for imparting heat resistance after film formation, and furthermore, when providing an adhesive layer, use a release paper or the like to adhere. Adhesive tape base film and adhesive using it, which can apply the adhesive directly to the film without transferring the agent, and the film elongation by heating in the drying process is small, and the heat shrinkage after the drying process is small. To provide a tape.

[0009]

Means for Solving the Problems As a result of diligent research for solving the above-mentioned problems, a base film for an adhesive tape having the following constitution was found. (1) A base film for an adhesive tape, which is a film containing a polypropylene-based resin as a main component, and has a creep compliance at 90 ° C. of 10 to 70 GPa ⁻¹ . (2) The base film for an adhesive tape according to (1), wherein the film has a three-layer structure having skin layers on at least both sides of a core layer. (3) The core layer is made of polypropylene resin, ethylene,
The base film for an adhesive tape according to (2), comprising a thermoplastic polyolefin resin blended with a copolymer comprising at least two monomers selected from propylene and butene. (4) The base film for an adhesive tape according to (2) or (3), wherein the skin layer is a polyolefin-based resin composition. (5) The tensile modulus of the film is 50 to 500 MPa.
The substrate film for an adhesive tape according to any one of (1) to (4), wherein (6) The substrate film for an adhesive tape according to any one of (1) to (5), wherein the film has a thickness of 20 to 150 μm. (7) An adhesive tape in which an adhesive layer is provided on one surface of the adhesive tape base film described in any one of (1) to (6).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a film containing a polypropylene resin as a main component, and has a creep compliance at 90 ° C. of 10 to 70 GPa ⁻¹ , preferably 10 to 60 GPa ⁻¹ , more preferably 10-5
It is a base film for an adhesive tape, wherein the base film is ⁰ GPa ^-1 . The creep compliance at 90 ° C. is defined as a width of 10 mm and a thickness of 100 in an atmosphere at a temperature of 90 ° C.
A value obtained by subtracting the strain at 30 ° C. from the strain when a load of 100 gf is applied to a μm sample for 30 minutes and dividing the resulting value by the stress. If the creep compliance at 90 ° C. is less than 10 GPa ⁻¹ , the rigidity of the film is high and the flexibility is poor, so that the curved surface followability is poor. On the other hand, creep compliance at 90 ° C is 7
When it is larger than 0 GPa ^−1, the deformation of the film due to heating in the drying step at the time of applying the pressure-sensitive adhesive becomes large. The curved surface followability means that, when a film coated with an adhesive is attached to a curved surface or a projection, when the film is not peeled off from the adhered surface due to repulsion due to the rigidity of the film, the curved surface followability is good.

The film is mainly made of a polypropylene resin and is not particularly limited as long as it satisfies the above physical properties. For example, a single layer may be used, but a laminated film having at least a three-layer structure is preferable. Core layer /
The configuration of the skin layer is preferred.

Particularly, the core layer is made of a polypropylene resin,
The thermoplastic polyolefin-based resin is preferably a thermoplastic polyolefin-based resin containing a copolymer of at least two monomers selected from ethylene, propylene, and butene. The skin layer formed on both surfaces of the core layer is preferably a polyolefin-based resin. It preferably comprises a composition.

The polypropylene resin used for the core layer includes not only homopolymer of polypropylene but also α, typified by ethylene, butene, 4-methylpentene and the like.
-Olefins, aromatic olefins represented by styrene, and copolymers of propylene and a monomer copolymerizable with polypropylene such as dienes represented by butadiene, and a copolymer component of the copolymer The amount is not limited.

The core layer is formed by adding the polypropylene resin
Use is made of a thermoplastic polyolefin-based resin in which a copolymer composed of at least two monomers among ethylene, propylene and butylene is blended and blended by a method such as a blend alloy or a reactor alloy. Examples of the blend alloy include "CAP" manufactured by Ube Industries, Ltd., and examples of the reactor alloy include "FPO" manufactured by Lexen, "Cataroy" manufactured by Montell SDC Sunrise, and the like. However, it is not limited to this.

The core layer contains additives such as antioxidants such as phenylenediamine and hindered phenol, antistatic agents such as glycerin monoester and ethoxylated amine, and ultraviolet absorbers such as benzotriazole. Is also good.

The skin layer is provided to avoid a blocking phenomenon due to self-adhesion of the core layer surface. Therefore, it is composed of components different from the components of the core layer.
The polyolefin-based resin composition used for the skin layer is a homopolymer such as polyethylene, polypropylene, polybutene, or a copolymer thereof. For the skin layer, silica, talc, diatomaceous earth,
Anti-blocking agents such as organic pigments, lubricants such as erucamide, stearamide, and oleamide; antioxidants such as phenylenediamine and hindered phenol; antistatic agents such as glycerin monoester and ethoxylated amine; and benzotriazole UV absorbers and the like may be added.

Incidentally, a layer may be formed between the core layer and the skin layer if necessary. Moreover, it is preferable to perform corona treatment on the surface of the skin layer in the present invention in order to improve anchoring of the pressure-sensitive adhesive. It is more preferable to perform the corona treatment so that the wetting index after the corona treatment is 35 dyne / cm or more.

Further, the present inventors have conducted intensive studies on the elastic modulus by a tensile test and the bending stiffness by a loop stiffness tester (manufactured by Toyo Seiki Co., Ltd.) for measuring the bending stiffness of a film or sheet. Even if it satisfies, it has been found that when the tensile elastic modulus is larger than 500 MPa, the bending rigidity is large and the curved surface followability tends to be poor. If the tensile elastic modulus of the base film for an adhesive tape is smaller than 50 MPa, the deformation of the film due to heating in the drying step at the time of applying the adhesive becomes large. If it is larger than 500 MPa, the rigidity of the film is high and the flexibility is inferior, so that the curved surface followability is poor. Therefore, the tensile modulus of the base film for an adhesive tape is preferably 50 to 500 MPa, more preferably 100 to 500 MPa.
~ 450MPa, more preferably 150 ~ 400MPa
It is.

Furthermore, it has been found that when the film thickness exceeds 150 μm even when the elastic modulus is 500 MPa or less, the curved surface followability tends to deteriorate due to the rigidity of the film itself due to the thickness. When the thickness of the base film for an adhesive tape is smaller than 20 μm, the base film has a small cross-sectional area, so that the base film is easily broken by a tensile load. Therefore, when used as an adhesive tape, it is difficult to use it as an adhesive tape because of its low tensile strength. 150 μm
When it is larger, the rigidity of the film is increased and the flexibility is inferior, so that the curved surface followability tends to be deteriorated. Therefore, the thickness of the adhesive tape base film is 20 to 150 μm.
m is preferable, and more preferably about 30 to 140 μm,
More preferably, it is about 40 to 130 μm.

Examples of the pressure-sensitive adhesive for applying the pressure-sensitive adhesive to the base film for a pressure-sensitive adhesive tape of the present invention include a rubber-based pressure-sensitive adhesive and an acrylic pressure-sensitive adhesive. A crosslinking agent, a tackifier and the like are appropriately blended with the pressure-sensitive adhesive. Examples of the release agent include an organic release agent and a silicon release agent. As a device for applying these pressure-sensitive adhesives, an ordinary coating machine such as a knife coater, a roll coater, a comma coater, a bar coater, and a gravure coater can be used. Examples of the coating device for the release agent include a gravure coater, a bar coater, and a roll coater.
Coating amount is preferably from 10 to 30 g / m ² with respect to the adhesive, preferably 0.2 to 2 g / m ² with respect to the release agent.

[0021]

The present invention will be described in more detail with reference to the following Examples, which, of course, are not intended to limit the scope of the present invention. Various physical properties and evaluations were performed by the following methods.

Example 1 "Production of base film for pressure-sensitive adhesive tape" A base film for pressure-sensitive adhesive tape having a three-layer structure of skin layer / core layer / skin layer having a thickness of 100 µm was formed by an air-cooled multilayer inflation method using a circular die. A film was formed. The temperature of the die was 220 ° C. The thickness of each layer is 15 μm for one skin layer and 70 μm for the core layer. As the thermoplastic polyolefin resin for the core layer, a thermoplastic polyolefin having a density of 0.88 g / cm ³ and a melt flow rate (MFR) of 0.45 g / 10 min (a blend of an ethylene-propylene copolymer with a polypropylene resin) , Product name: KS-3
53P, manufactured by Montell SDC Sunrise)
Was used. Further, as a resin for the skin layer, the density is 0.9.
Linear low-density polyethylene (LLDPE) having a 2 g / cm ³ and MFR of 0.85 g / 10 min (trade name: AF33)
1S, manufactured by Nippon Polyolefin Co., Ltd.).

[Preparation of pressure-sensitive adhesive tape] The base film for a pressure-sensitive adhesive tape was coated so as to provide a release agent layer on one side and a pressure-sensitive adhesive layer on the other side. The release agent layer was coated with an organic release agent (Piroyl 1010, manufactured by YAS Co., Ltd.) using a bar coater so as to have a coating amount of 0.1 g / m ² . The pressure-sensitive adhesive layer was coated with a composition comprising 20 parts by weight of natural rubber, 20 parts by weight of a tackifier resin (YS resin 700, manufactured by Yashara Chemical Co., Ltd.) and 60 parts by weight of toluene.
Coating was performed with a knife coater so as to be 0 g / m ² . At this time, the temperature in the drying step was 90 ° C.

Example 2 The thermoplastic polyolefin resin for the core layer has a density of 0.88 g / cm ³ and an MFR of 0.45 g / 10 min.
(Polypropylene resin blended with ethylene-propylene copolymer, trade name: KS-353P, manufactured by Montell SDC Sunrise), having a density of 0.90 g / cm ³ and an MFR of 2 0.5 g / min polypropylene (trade name: RF13
42, manufactured by Grand Polymer Co.)
A blend was used. LL as resin for skin layer
Using DPE (trade name: AF331S, manufactured by JPO), a film was formed by an air-cooled multilayer inflation method using a circular die. The temperature of the die was 220 ° C. The thickness of each layer is 15 μm for one skin layer and 7 μm for the core layer.
0 μm. Table 1 shows various physical properties and evaluations of the formed three-layer laminated 100 μm film. "Production of adhesive tape" An adhesive tape was obtained in the same manner as in Example 1.

Example 3 The thermoplastic polyolefin resin for the core layer has a density of 0.88 g / cm ³ and an MFR of 0.45 g / 10 min.
(Polypropylene resin blended with an ethylene-propylene copolymer, trade name: KS-353P, manufactured by Montell S.D. Sunrise Co., Ltd.). LLDP as resin for skin layer
E (trade name: AF331S, manufactured by JPO) was used to form a film by an air-cooled multilayer inflation method using a circular die. The temperature of the die was 220 ° C. The thickness of each layer is 5 μm for one skin layer and 20 μm for the core layer. Table 1 shows various physical properties and evaluations of the formed three-layer laminated 30 μm film. "Production of adhesive tape" An adhesive tape was obtained in the same manner as in Example 1.

Example 4 The thermoplastic polyolefin resin for the core layer has a density of 0.88 g / cm ³ and an MFR of 0.45 g / 10 min.
(Polypropylene resin blended with an ethylene-propylene copolymer, trade name: KS-353P, manufactured by Montell S.D. Sunrise Co., Ltd.). LLDP as resin for skin layer
E (trade name: AF331S, manufactured by JPO) was used to form a film by an air-cooled multilayer inflation method using a circular die. The temperature of the die was 220 ° C. The thickness of each layer is 35 μm for one skin layer and 70 μm for the core layer. Table 1 shows various physical properties and evaluations of the formed three-layer laminated 140 μm film. "Production of adhesive tape" An adhesive tape was obtained in the same manner as in Example 1.

Comparative Example 1 As a thermoplastic polyolefin resin for the core layer, polypropylene (trade name: RF1342, manufactured by Grand Polymer) having a density of 0.90 g / cm ³ and an MFR of 2.5 g / 10 min, and a resin for the skin layer Using LLDPE (trade name: AF331S, manufactured by Nippon Polyolefin Co., Ltd.), a film was formed by an air-cooled multilayer inflation method using a circular die. The temperature of the die was 220 ° C. The thickness of each layer is 5 μm for one skin layer and 90 μm for the core layer.
μm. Table 1 shows various physical properties and evaluations of the formed three-layer laminated 100 μm film. "Production of adhesive tape" An adhesive tape was obtained in the same manner as in Example 1.

Comparative Example 2 The thermoplastic polyolefin resin for the core layer has a density of 0.924 g / cm ³ and an MFR of 1.0 g / 10 min.
Low density polyethylene (LDPE) (trade name: JF33)
0N, manufactured by JPO) and LL as the resin for the skin layer
Using DPE (trade name: AF331S, manufactured by Nippon Polyolefin Co., Ltd.), a film was formed by an air-cooled multilayer inflation method using a circular die. Die temperature 22
0 ° C. The thickness of each layer is 15 μm for one skin layer,
The core layer is 70 μm. Table 1 shows various physical properties and evaluations of the formed three-layer laminated 100 μm film. "Production of adhesive tape" An adhesive tape was obtained in the same manner as in Example 1.

Comparative Example 3 A single-layer 100 μm polyvinyl chloride film manufactured by Achilles was used as a film using a soft polyvinyl chloride resin. Table 1 shows various physical properties and evaluations of this film. "Production of adhesive tape" An adhesive tape was obtained in the same manner as in Example 1.

Example 5 The thermoplastic polyolefin resin for the core layer has a density of 0.88 g / cm ³ and an MFR of 0.45 g / 10 min.
(Polypropylene resin blended with an ethylene-propylene copolymer, trade name: KS-353P, manufactured by Montell S.D. Sunrise Co., Ltd.). LLDP as resin for skin layer
E (trade name: AF331S, manufactured by JPO) was used to form a film by an air-cooled multilayer inflation method using a circular die. The temperature of the die was 220 ° C. The thickness of each layer is 1 μm for one skin layer and 8 μm for the core layer. Table 1 shows various physical properties and evaluations of the formed three-layer laminated 10 μm film. "Production of adhesive tape" An adhesive tape was obtained in the same manner as in Example 1.

Example 6 The thermoplastic polyolefin resin for the core layer has a density of 0.88 g / cm ³ and an MFR of 0.45 g / 10 min.
(Polypropylene resin blended with an ethylene-propylene copolymer, trade name: KS-353P, manufactured by Montell S.D. Sunrise Co., Ltd.). LLDP as resin for skin layer
E (trade name: AF331S, manufactured by JPO) was used to form a film by an air-cooled multilayer inflation method using a circular die. The temperature of the die was 220 ° C. The thickness of each layer is 30 μm for one skin layer and 100 μm for the core layer.
It is. Table 1 shows various physical properties and evaluations of the formed three-layer laminated 160 μm film. "Production of adhesive tape" An adhesive tape was obtained in the same manner as in Example 1.

Example 7 The thermoplastic polyolefin resin for the core layer had a density of 0.89 g / cm ³ and an MFR of 0.80 g / 10 min.
(Polypropylene resin blended with an ethylene-propylene copolymer, trade name: KS-021P, manufactured by Montell SDC Sunrise Co., Ltd.). In order to impart blocking resistance, talc was added in an amount of 0.5 part by weight based on 100 parts by weight of the resin. A film was formed to a thickness of 100 μm by an air-cooled single-layer inflation method using a circular die. The temperature of the die was 220 ° C. 100μ molded
Table 1 shows various physical properties and evaluations of the m film. "Production of adhesive tape" An adhesive tape was obtained in the same manner as in Example 1.

The physical properties and evaluation of the obtained base film for pressure-sensitive adhesive tape and the evaluation of the obtained pressure-sensitive adhesive tape were performed according to the following criteria. The results are shown in Table 1.

(1) Creep Compliance The obtained film was made to have a width of 10 mm and a film thickness of 10 mm in a 90 ° C. atmosphere using a thermomechanical measuring device (DMS6100, manufactured by Seiko Instruments Inc.).
A value obtained by subtracting the strain at 30 ° C. from the strain when a load is applied at a rate of 100 gf per 0 μm for 30 minutes, and dividing this by the stress.

(2) Tensile modulus The obtained film was determined in accordance with JIS K-7127. (3) Tensile strength The obtained film was determined in accordance with JIS K-7127.

(4) Opening The film formed by the air-cooled multilayer inflation method was rated as good when opened by tearing and opened when it was difficult to open.

(5) Blocking Resistance The obtained film is cut into a square of 50 mm × 50 mm, and two of them are laminated as a sample. Prepare five sets of samples. This sample is sandwiched between 60 mm × 60 mm holding plates, and a weight of 2 kg is placed thereon, at a temperature of 40 ± 1 ° C. and a humidity of 70%.
It is left for 1 day under the condition of ± 2% RH and for 3 days under the condition of a temperature of 50 ± 1 ° C. and no humidity limitation. When the sample is peeled off by hand and peeled off, it is regarded as good, and when it is not peeled off, it is regarded as bad.

(6) Thermal Deformability When the adhesive is applied, the case where the base film hardly elongates in the drying step is regarded as good, and the case where the film elongates is regarded as bad.

(7) Curved surface followability The obtained adhesive tape was stuck on a metal plate of 100φ and left at a temperature of 23 ° C. and a humidity of 65% RH, and no lifting occurred at the end of the adhesive tape. Were evaluated as good, and those that were lifted were regarded as poor, and those in which no pressure-sensitive adhesive tape was obtained due to thermal deformation in the manufacturing process were regarded as impossible.

[0040]

[Table 1]

Table 1 shows that the base film for an adhesive tape obtained in the example and the adhesive tape using the same were obtained in Comparative Example 1.
3 are more excellent in heat resistance, flexibility, followability to a curved surface, tensile strength, opening property, and blocking resistance than those obtained in Nos. 1 to 3. In Example 5, since the film thickness was as thin as 10 μm, the tensile strength was insufficient, and in Example 6, since the film was as thick as 160 μm, the ability to follow a curved surface was poor. Depending on the case, it may not be usable.

[0042]

According to the present invention, the heat resistance, flexibility, followability to curved surfaces, tensile strength, openability, blocking resistance and the like are equal to or higher than those of soft vinyl chloride resin. Because no plasticizer is used, there is no deterioration in appearance due to migration of the plasticizer to the film surface,
A substrate film for a pressure-sensitive adhesive tape and a pressure-sensitive adhesive tape using the same without a problem of odor of a plasticizer are obtained, and are extremely useful in the industry.

Continued on the front page F-term (reference) 4F071 AA15 AA20 AF13Y AH19 BC01 4F100 AK03B AK03C AK07 AK25G AK62B AK62C AK63 AK64 AK64A AK66A AK66B AK66C AL05 AN02G AR00D BA01 BA03 E04 BA10 BA10 BA10 BA10 BA10 BA10 BA10 BA10 JK17 JL00 JL13D YY00 4J002 BB052 BB121 BB141 BB142 BB151 BB152 GF00 4J004 AA05 AA10 AB01 CA04 CB03 CC03 CD08 CE01 DA04 DA05 DB01

Claims (7)

[Claims] 1. A base film for an adhesive tape, which is a film mainly composed of a polypropylene resin and has a creep compliance at 90 ° C. of 10 to 70 GPa ⁻¹ . 2. The base film for an adhesive tape according to claim 1, wherein the film has a three-layer structure having skin layers on at least both sides of a core layer. 3. The pressure-sensitive adhesive according to claim 2, wherein the core layer is made of a thermoplastic polyolefin resin in which a copolymer of at least two monomers selected from ethylene, propylene and butene is blended with a polypropylene resin. Base film for tape. 4. The base film for an adhesive tape according to claim 2, wherein the skin layer is a polyolefin resin composition. 5. A film having a tensile modulus of 50 to 500.
The substrate film for an adhesive tape according to any one of claims 1 to 4, which is MPa. 6. The base film for an adhesive tape according to claim 1, wherein the thickness of the film is 20 to 150 μm. 7. A pressure-sensitive adhesive tape, comprising a pressure-sensitive adhesive layer provided on one surface of the base film for a pressure-sensitive adhesive tape according to any one of claims 1 to 6.