JP2016186015A - Adhesive composition and adhesive tape or sheet comprising adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition that offers an excellent balance of tack, adhesive power, and holding power even when its coating thickness is 10 μm or less, and an adhesive tape or sheet comprising the adhesive composition.SOLUTION: An adhesive composition comprises an SIS with a diblock ratio of 40-70% or less, a natural rubber with a Mooney viscosity (ML) of 40-50, a C5 petroleum resin with a softening point of 90°C or less, a coumarone resin, and a petroleum plasticizer.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive tape or sheet containing the pressure-sensitive adhesive composition, which have excellent practical characteristics even when the coating thickness is thin.

  The rubber-based pressure-sensitive adhesive is required to have excellent tack, adhesion and holding power as practical characteristics.

  A conventional rubber-based pressure-sensitive adhesive is, for example, a blended pressure-sensitive adhesive composition containing natural rubber and a specific amount of a styrene-isoprene block copolymer (SIS), without reducing the pressure-sensitive adhesive performance. The unwinding force can be reduced (Patent Document 1). Furthermore, by having a pressure-sensitive adhesive composition containing a specific amount of styrene-isoprene type block copolymer, a specific amount of SIS, and natural rubber, it has excellent adhesive properties such as adhesiveness and cold resistance. At the same time, it is possible to make the coating workability good with low viscosity and high solid content, and to make the cost appropriate (Patent Document 2).

JP-A-5-263052 JP-A-7-268297

  Here, the pressure-sensitive adhesive composition was required to exhibit sufficient practical characteristics even when the coating thickness was about 10 μm with the goal of cost reduction and the like. However, the pressure-sensitive adhesive compositions according to Patent Document 1 and Patent Document 2 have an excellent balance of tack, adhesive strength, and holding power, and can exhibit a practical level of adhesive properties even with a coating thickness (adhesive thickness) of about 20 μm. When the coating thickness was reduced to 10 μm or less, tack and adhesive strength were significantly reduced, and practical characteristics were not exhibited.

  Then, even if application | coating thickness is 10 micrometers or less, this invention makes it a subject to provide the adhesive tape and the adhesive tape or sheet containing an adhesive composition which are excellent in the balance of a tack, adhesive force, and holding power.

  As a result of intensive studies in view of the above problems, the present inventors set the Mooney viscosity of natural rubber within a specific range, the SIS diblock ratio within a specific range, and further blending a specific tackifier. As a result, it was found that even when the coating thickness was 10 μm or less, the practical characteristics were hardly lowered. That is, the present invention includes the following (1) to (3).

The present invention (1)
A pressure-sensitive adhesive composition comprising a styrene-isoprene-styrene block copolymer (SIS), natural rubber, a tackifier, and a petroleum plasticizer,
The diblock ratio of the SIS is 40% or more and 70% or less,
The Mooney viscosity (ML) of the natural rubber is 40 or more and 50 or less,
The tackifier is a pressure-sensitive adhesive composition containing a C5 petroleum resin having a softening point of 90 ° C. or less and a coumarone resin.
The present invention (2)
A film substrate;
An adhesive tape or sheet having an adhesive layer provided on at least one side of the film substrate,
The pressure-sensitive adhesive layer is
A styrene-isoprene-styrene block copolymer (SIS), natural rubber, a tackifier, and a petroleum plasticizer,
The diblock ratio of the SIS is 40% or more and 70% or less,
The Mooney viscosity (ML) of the natural rubber is 40 or more and 50 or less,
The tackifier is an adhesive tape or sheet containing a C5 petroleum resin having a softening point of 90 ° C. or less and a coumarone resin.
This invention (3) is an adhesive tape or sheet | seat of the said invention (2) whose average thickness of the said adhesive layer is 10 micrometers or less.

  ADVANTAGE OF THE INVENTION According to this invention, even if application | coating thickness is 10 micrometers or less, it becomes possible to provide the adhesive tape or sheet | seat containing an adhesive composition and an adhesive composition which is excellent in the balance of tack, adhesive force, and holding power.

  In the pressure-sensitive adhesive tape according to the present invention, a pressure-sensitive adhesive layer is formed on a substrate. Hereinafter, the material of the pressure-sensitive adhesive tape, the structure of the pressure-sensitive adhesive tape, the method for producing the pressure-sensitive adhesive tape, the physical properties of the pressure-sensitive adhesive tape, and the application of the pressure-sensitive adhesive tape will be described in order.

≪Adhesive tape material≫
The pressure-sensitive adhesive layer and the substrate of the pressure-sensitive adhesive tape according to the present invention will be described in detail.

<Adhesive layer>
{component}
The pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer of the present invention comprises a styrene-isoprene-styrene block copolymer (hereinafter referred to as SIS) and natural rubber as an elastomer component, a tackifying resin component, and a petroleum plasticizer. And ingredients. Hereinafter, each component and blending will be described.

(Elastomer)
The elastomer according to the present invention is a styrene-isoprene-styrene block copolymer (hereinafter referred to as SIS) and natural rubber. Each will be described below.

・ SIS
In the SIS according to the present invention, the SIS diblock ratio is 40% or more and 70% or less. When the diblock ratio of SIS is less than 40%, the pressure-sensitive adhesive becomes too hard and the initial tack and tackiness are lowered, and when it exceeds 70%, the pressure is too soft and the cohesive force is lowered. Here, it is preferable to use a SIS diblock ratio of 50% or more. By setting it to 50% or more, the hardness (generally indicated by Shore A) is low and the elongation is high, so when mixed with an adhesive, the adherence to the fine uneven surface of the adherend is excellent, so the initial tack And the adhesive strength can be improved.

  Here, the diblock ratio of SIS is generally measured by the diblock / triblock peak area ratio obtained from GPC measurement (using a styrene gel column, THF mobile phase).

  In addition, it is preferable to use a styrene content of SIS of 20% by mass or less as a general adhesive application. By setting it as 20 mass% or less, the elasticity modulus of an elastomer becomes a desirable range, and the fall of adhesive characteristics, such as a tack and adhesive force, can be prevented. Although it does not specifically limit as a lower limit of styrene content, For example, it is 5 mass%, Preferably it is 10 mass%, More preferably, it is 14 mass%.

  Here, the measurement of the styrene content was calculated by a refractive index using an Abbe refractometer according to JIS Z7142.

  In addition, SIS may be used independently and 2 or more types of mixtures (for example, mixture of SIS containing high styrene and SIS containing low styrene) may be sufficient. Moreover, as a diblock rate of SIS at the time of setting it as a 2 or more types of mixture, the diblock rate of the whole SIS is computable by the average value based on a weight.

-Natural rubber The natural rubber according to the present invention is a rubbery polymer substance obtained mainly from natural plants, and is a rubber from which most of the protein contained in raw rubber has been removed. Also included are synthetic rubbers having

  The Mooney viscosity of the natural rubber used in this embodiment is 40 or more and 50 or less. When the Mooney viscosity of the natural rubber is more than 50, the pressure-sensitive adhesive itself becomes hard. Therefore, particularly when the coating thickness is 10 μm or less, the tackiness and the decrease in the adhesive strength are remarkable, and the Mooney viscosity of the natural rubber is less than 40. Due to the decrease in cohesive force, the retention force decreases particularly when the coating thickness is 10 μm or less. Here, Mooney viscosity is a value measured at 100 ° C. in accordance with JIS K6300-2013. The Mooney viscosity can be adjusted as appropriate by kneading. The natural rubber may be a mixture of a plurality of types.

  Examples of natural rubber include smoked sheet, pale crepe, air dried sheet, skim rubber, SP rubber, TC rubber, and MG rubber. Natural rubber can be kneaded to break down the high molecular weight gel rubber, lower the average molecular weight, and narrow the molecular weight distribution. Natural rubber can control the adhesive properties by mastication, and further facilitates mixing with tackifier resins, other rubbers, additives and the like.

(Tackifying resin)
The tackifying resin according to the present invention includes a C5 petroleum resin and coumarone resin at 90 ° C. or lower.

C5-based petroleum resin C5-based petroleum resin is a petroleum resin whose main raw material is a C5 fraction obtained by naphtha decomposition.

  Here, by using a C5 petroleum resin having a softening point of 90 ° C. or less as a tackifying resin, even when the coating thickness is 10 μm or less, it is possible to develop a good tack while maintaining an appropriate cohesive force. I have to. Although the lower limit of a softening point is not specifically limited, It is 70 degreeC or more. Here, the softening point is a value obtained by a softening point test method by a ring and ball method according to “Japanese Industrial Standards” JIS K2207-1996.

  In addition, a C5 petroleum resin having a softening point of 90 ° C. or less may be used together with a C5 petroleum resin having a softening point of more than 90 ° C. (In this case, a C5 petroleum resin having a softening point of 90 ° C. or less may be used). Including the effect of the present invention).

Coumarone resin Coumarone resin is a copolymer of coumarone alone or a copolymer obtained by polymerizing coumarone, indene, styrene, etc., and is not particularly limited.

  By using a coumarone resin as the tackifier resin, it is possible to impart an appropriate cohesive force while maintaining good tack even when the coating thickness is 10 μm or less.

-Other tackifying resins In the pressure-sensitive adhesive composition according to the present invention, natural products such as rosin resins and terpene resins and derivatives thereof, aliphatic petroleum resins, Adhesives such as aliphatic / aromatic resins, alicyclic petroleum resins, aromatic petroleum resins, aromatic / aliphatic resins, styrene resins, phenolic resins, xylene resins, and hydrogenated resins thereof An imparting resin may be blended.

(Petroleum plasticizer)
Examples of the petroleum plasticizer according to the present invention include paraffinic process oil, naphthenic process oil, and aromatic process oil. In particular, naphthenic process oils are preferred because they are more compatible with other components, making design easier, providing well-balanced adhesive properties, and reducing viscosity at high temperatures. It is.

(Other ingredients)
The pressure-sensitive adhesive composition of the present invention may contain various additives as necessary within a range that does not impair the object of the present invention. For example, a softener, a plasticizer, a filler, a stabilizer, a colorant. Various additives generally used in pressure-sensitive adhesive compositions such as viscosity modifiers may be contained. Moreover, you may mix | blend elastomer components other than SIS and natural rubber in the range which does not inhibit the objective of this invention.

{Formulation}
(Elastomer content)
-Blending amount of SIS The use ratio of SIS is preferably 30 to 70% by weight, more preferably 40 to 60% by weight in the elastomer component (total weight of SIS and natural rubber). If the use ratio of SIS is too large, the tack may tend to decrease. On the other hand, if the use ratio of SIS is too small, the cohesive force may be insufficient and the adhesive force may be reduced.

-Blending amount of natural rubber The use ratio of natural rubber is preferably 30 to 70% by weight, more preferably 40 to 70% by weight in the elastomer component (the combined weight of SIS and natural rubber). If the use ratio of the natural rubber is too small, it may be difficult to obtain a good tack, and if the use ratio of the natural rubber is too large, sufficient tackiness may not be obtained.

(Blend amount of tackifying resin)
-Blending amount of C5 petroleum resin with a softening point of 90 ° C or lower The C5 petroleum resin with a softening point of 90 ° C or lower is usually 20 to 150 parts by weight with respect to 100 parts by weight of the elastomer component (the combined weight of SIS and natural rubber). , Preferably 30 to 100 parts by weight. If this use ratio is too small, sufficient tackiness may not be obtained, and if it is too large, tack may be lowered.

-Blending amount of coumarone resin Coumarone resin is used in a proportion of 50 parts by weight or less, preferably 30 parts by weight or less, based on 100 parts by weight of the elastomer component (total weight of SIS and natural rubber). If this use ratio is too large, the tack may decrease. In addition, although it does not specifically limit as a lower limit, For example, it is 5 weight part.

(Amount of petroleum plasticizer)
The petroleum plasticizer is preferably used in a proportion of usually 100 parts by weight or less, preferably 70 parts by weight or less, based on 100 parts by weight of the elastomer component (the combined weight of SIS and natural rubber). If the use ratio is too large, sufficient cohesive force cannot be obtained, and the retention may be lowered. In addition, although it does not specifically limit as a lower limit, For example, it is 10 weight part.

{effect}
By using the pressure-sensitive adhesive composition according to the present invention, tack, pressure-sensitive adhesive strength and cohesive strength can be optimized, and as a result, excellent pressure-sensitive adhesive performance can be obtained even with a thin pressure-sensitive adhesive thickness (10 μm or less) (pressure-sensitive adhesive thickness). Even if the thickness is reduced, excellent adhesive performance can be maintained).

<Base material>
The base material of the pressure-sensitive adhesive tape according to the present invention is not particularly limited. For example, a porous material formed from a fibrous material such as kraft paper, crepe paper, Japanese paper, polyolefin resin, polyester resin, vinyl chloride A plastic film formed of a resin, a polyimide resin, a cellulose resin, or the like can be given.

  Here, when the porous material is used, a material appropriately treated with an impregnating agent, a back surface treating agent or the like may be used in order to adjust properties such as strength, weather resistance and rigidity. The basis weight and thickness of the porous material are appropriately selected depending on the application and are not particularly limited.

  In addition to the above-described plastic film, the use of a biodegradable or photodegradable plastic film can be preferable from the environmental viewpoint. Further, a plurality of the above-mentioned ones can be used in combination, and the above-mentioned plastic films can be used together or a plastic film and a porous material can be laminated. Moreover, a porous plastic film can also be used as needed. In addition, surface treatment such as corona treatment, plasma treatment, and primer treatment may be applied to one or both sides of the plastic film in order to improve the adhesion with the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer. The basis weight of the base material using this plastic film can be used without any particular limitation. Among them, it is preferable to use a plastic film substrate having a smooth surface structure in order to feature performance at a thin adhesive thickness.

≪Adhesive tape structure≫
The pressure-sensitive adhesive tape according to the present invention only needs to have a configuration in which the pressure-sensitive adhesive layer can be exposed on at least one side at the time of use, such as a pressure-sensitive adhesive layer / base material, and a pressure-sensitive adhesive layer / base material / pressure-sensitive adhesive layer. It may be a laminated structure of two or more layers, such as a structure to be used, or may further be provided with a release sheet (a sheet for protecting the adhesive layer that can be removed during use) that covers the adhesive layer.

  The average thickness of the pressure-sensitive adhesive layer according to the present invention is not particularly limited and can be 5 μm to 30 μm or the like. However, since the pressure-sensitive adhesive tape according to the present invention uses the above-described pressure-sensitive adhesive, Excellent practical characteristics are exhibited even when the average thickness is 10 μm or less. In addition, the average thickness of the pressure-sensitive adhesive layer shown here is a value obtained by subtracting the average thickness of the base material from the average thickness of the entire tape in accordance with the method for measuring the thickness of JIS Z0237.

  Here, when the pressure-sensitive adhesive tape has a plurality of pressure-sensitive adhesive layers, the thicknesses thereof may be different from each other (for example, in the case of the configuration of pressure-sensitive adhesive layer A / base material / pressure-sensitive adhesive layer B, The average thickness of the layer A is 10 μm, the average thickness of the pressure-sensitive adhesive layer B is 30 μm, etc.).

  The pressure-sensitive adhesive tape according to the present invention can be appropriately changed according to the intended use with respect to the thickness of the base material, the thickness of the entire tape (including the base material and the pressure-sensitive adhesive layer), width, length, and the like. Moreover, it is good also as arbitrary shapes, such as tape shape and a sheet form.

≪Method of manufacturing adhesive tape≫
Although it does not specifically limit as a manufacturing method of an adhesive tape, For example, it can manufacture with the following method.

  Organic solvent (for example, toluene, normal hexane, ethyl acetate, etc.) in which the adhesive component can be dissolved in an agitator type stirring tank (stirring method in which a stirring shaft having a triangular wing reverses every 1/4 rotation) for each component Use to stir and dissolve to prepare an adhesive solution.

  A pressure-sensitive adhesive tape can be obtained by applying the pressure-sensitive adhesive thus obtained onto the above-described substrate and drying it appropriately.

  As a method for applying the adhesive, for example, it can be applied by a system such as a knife coater, a gravure coater, a roll coater, a lip coater, or a die coater.

≪Physical properties of adhesive tape≫
The pressure-sensitive adhesive tape according to the present invention exhibits excellent practical characteristics even when the thickness (average thickness) of the pressure-sensitive adhesive layer is 10 μm or less. Hereinafter, the characteristics of the pressure-sensitive adhesive tape according to the present invention when the thickness (average thickness) of the pressure-sensitive adhesive layer is 10 μm or less will be described.

(Vs. SUS adhesive strength)
The adhesive strength with respect to SUS of the adhesive tape which concerns on this invention can be 8 N or more. The test method for SUS adhesive strength is as follows.

[Test of SUS adhesive strength]
A sample with a width of 25 mm was attached to a SUS panel in an atmosphere of 23 ° C. and 50% RH, and was pressed once with a 2 kg rubber roll at a speed of 300 mm / min. After leaving for 20 minutes, a peeling angle of 180 ° and a peeling speed of 300 mm / Measure the peel force of the minute.

(Resistance to glass plate)
The adhesive force with respect to the glass plate of the pressure-sensitive adhesive tape according to the present invention can be 1 mm or less. The glass plate holding force test method is as follows.

[Test of holding power against glass plate]
In accordance with JIS Z-0237, a sample having a width of 12 mm is pasted on a glass plate in an area of 12 mm × 20 mm in an atmosphere of 23 ° C. and 50% RH, and is subjected to one-way pressure bonding with a 2 kg rubber roll at a speed of 300 mm / min. After leaving for 20 minutes, the adhesive sheet is hung so as to hang vertically, a load of 1 kg is applied, and the displacement length after 60 minutes is measured. If the load falls within 60 minutes, record the drop time.

(Ball tack)
The ball tack of the pressure-sensitive adhesive tape according to the present invention can be 10 or more. The ball tack test method is as follows.

[Ball tack test]
In accordance with JIS Z0237, affixed with a 10 cm long adhesive tape on a stainless steel plate with an inclination angle of 30 degrees in an atmosphere of 23 ° C. and 50% RH, from the position 10 cm from the upper end of the adhesive tape, Thirty kinds of steel balls having a diameter of 2/32 to 1 inch are rolled at an initial speed of 0, and the maximum steel ball number that stops on the adhesive tape is defined as a ball tack value. The higher the ball tack value, the higher the initial adhesiveness.

(Probe tack)
The probe tack of the pressure-sensitive adhesive tape according to the present invention can be 8N or more. The probe tack test method is as follows.

[Probe tack test]
According to ASTM D-2979, using NS probe tack tester (manufactured by Nichiban Co., Ltd.), diameter of cylindrical contact (probe): 5 mm, pressing: 100 gf / cm ² , contact time: 1 second, peeling speed : Measured under the condition of 10 mm / sec.

(Envelope sealing)
The pressure-sensitive adhesive tape according to the present invention is excellent in envelope sealing properties. The envelope sealing property can be evaluated by the following method.

[Envelope sealing test]
A4 copy paper (3 sheets) is folded in four into a square type No. 7 (142 mm x 205 mm) envelope, sealed with a tape sample (15 x 100 mm), crimped with a 630 g roller, and opened 24 hours later Record the presence or absence.

(Cardboard packaging)
The pressure-sensitive adhesive tape according to the present invention is excellent in cardboard packaging properties. The cardboard packaging property can be evaluated by the following method.

[Cardboard packaging test]
Size of 530mm x 380mm x 260mm, single flute, grooved cardboard top and bottom flaps, closed with tape sample (50mm width) and sealed with I, and then the length of the part on the side of the cardboard The length of the tape sample is formed so that the length becomes 50 mm. Record the presence or absence of opening after 24 hours.

(Paper peelability)
The pressure-sensitive adhesive tape according to the present invention is excellent in paper peelability. The paper peelability test method is as follows.

[Test of paper peelability]
In a 5 ° C. atmosphere, a 15 mm wide tape sample is reciprocated once by a 630 g roller on a copy paper and pressed. The degree of peeling on the copy paper when it is immediately peeled off in the 180 ° direction is displayed in%.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples.

≪Raw material≫
<Elastomer>
{Natural rubber}
(A-1) Crepe rubber no. 1 Toyota Tsusho {SIS}
(B-1) Quintac 3520 Nippon Zeon Co., Ltd. Diblock ratio 78%
(B-2) Quintac 3433 Nippon Zeon Co., Ltd. Diblock ratio 56%
(B-3) Quintac 3421 Zeon Corporation Diblock ratio 26%
<Tackifying resin>
{C5 petroleum resin}
(C-1) Quinton M100 Softening point 95 ° C. Nippon Zeon Co., Ltd.
(C-2) Quinton N180 Softening point 80 ° C Nippon Zeon Co., Ltd.
{Coumarone resin}
(C-3) Knit Resin Coumarone V-120S Softening point 120 ° C. Nikko Chemical Co., Ltd.
{Terpene resin}
(C-4) YS Polystar T80 Softening point 80 ± 5 ° C. Yasuhara Chemical Co., Ltd.
{Rosin ester resin}
(C-5) Superester A75 Softening point 70-80 ° C. Arakawa Chemical Industries, Ltd.
<Petroleum plasticizer (process oil)>
{Naphthenic}
(D-1) SNH100 pour point-27.5 ° C. Sankyo Oil Chemical Co., Ltd.
<Antioxidant>
(E-1) Antage W-500 Bisphenol Kawaguchi Chemical Co., Ltd.

≪Manufacturing method≫
Example 1
Each component shown in Table 1 was stirred and dissolved in a toluene solvent to prepare a pressure-sensitive adhesive solution (solid content concentration of about 30%). The obtained pressure-sensitive adhesive solution was applied to a polyethylene terephthalate film having a thickness of 25 μm using a Baker type applicator so that the thickness of the pressure-sensitive adhesive after drying was 10 μm, and dried to prepare a pressure-sensitive adhesive tape.

(Examples 2-4, Comparative Examples 1-5)
Based on the components and formulations shown in Tables 1 and 2, adhesive tapes according to Examples 2 to 4 and adhesive tapes according to Comparative Examples 1 to 5 were produced in the same manner as in Example 1.

≪Evaluation results≫
In Tables 1 and 2, the adhesive tapes according to Examples and Comparative Examples are evaluated with respect to SUS adhesive strength, glass plate holding power, ball tack, probe tack, envelope sealing property, cardboard packaging property and paper peeling property. It was. The test method for each evaluation is as described above. The envelope sealing property and the cardboard packaging property were evaluated using the evaluation indexes shown below.
(Envelope sealing)
A: No peeling B: Only one short part is slightly exciting (10% or less)
C: Only one short part has a slight excitement (30% or less)
D: 50% or less exciting E: Full face peeling (cardboard packaging)
A: No peeling.
B: Stripping at 1/4 location C: Stripping at 2/4 location D: Stripping at 3/4 location or more

Claims (3)

A pressure-sensitive adhesive composition comprising a styrene-isoprene-styrene block copolymer (SIS), natural rubber, a tackifier, and a petroleum plasticizer,
The diblock ratio of the SIS is 40% or more and 70% or less,
The Mooney viscosity (ML) of the natural rubber is 40 or more and 50 or less,
The pressure-sensitive adhesive composition, wherein the tackifier comprises a C5 petroleum resin having a softening point of 90 ° C. or less and a coumarone resin. A film substrate;
An adhesive tape or sheet having an adhesive layer provided on at least one side of the film substrate,
The pressure-sensitive adhesive layer is
A styrene-isoprene-styrene block copolymer (SIS), natural rubber, a tackifier, and a petroleum plasticizer,
The diblock ratio of the SIS is 40% or more and 70% or less,
The Mooney viscosity (ML) of the natural rubber is 40 or more and 50 or less,
The pressure-sensitive adhesive tape or sheet, wherein the tackifier comprises a C5 petroleum resin having a softening point of 90 ° C. or less and a coumarone resin.   The adhesive tape or sheet of Claim 2 whose average thickness of the said adhesive layer is 10 micrometers or less.