HOT MELT ADHESIVE COMPOSITION, ADHESIVE TAPE, AND METHOD FOR PRODUCING ADHESIVE TAPE

Abstract

A hot melt adhesive composition which can realize moderate adhesive strength with respect to the adherend when porous substrate is used, the composition, including: a styrene-based block copolymer; a tackifier; and a plasticizer; wherein: the styrene-based block copolymer is a styrene-butadiene block copolymer and a butadiene portion thereof is partially hydrogenated; the tackifier is contained by 65 to 190 parts by mass with respect to 100 parts by mass of the styrene-based block copolymer; and the plasticizer is contained by 0.1 to 24 parts by mass with respect to 100 parts by mass of the styrene-based block copolymer.

Claims

1. A hot melt adhesive composition, comprising: a styrene-based block copolymer; a tackifier; and a plasticizer; wherein: the styrene-based block copolymer is a styrene-butadiene block copolymer and a butadiene portion thereof is partially hydrogenated; the tackifier is contained by 65 to 190 parts by mass with respect to 100 parts by mass of the styrene-based block copolymer; and the plasticizer is contained by 0.1 to 24 parts by mass with respect to 100 parts by mass of the styrene-based block copolymer.

2. The hot melt adhesive composition of claim 1, wherein the tackifier is a petroleum resin.

3. The hot melt adhesive composition of claim 2, wherein the petroleum resin is at least one selected from the group consisting of C5 petroleum resin, C5C9 petroleum resin, and hydrogenated C9 petroleum resin.

4. The hot melt adhesive composition of claim 1, wherein the plasticizer is DINA (diisononyl adipate).

5. An adhesive tape, comprising: a porous substrate; and an adhesive layer provided on the porous substrate; wherein: the adhesive layer comprises the hot melt adhesive composition of claim 1.

6. The adhesive tape of claim 5, wherein: the adhesive tape has an adhesive strength according to JIS Z0237 “10. adhesive strength” of 1.5 N/cm or more; and the adhesive tape has a holding strength according to JIS Z0237 “13. holding strength” of 10 min or more.

7. A method for manufacturing the adhesive tape of claim 5, comprising the step of: an applying step to apply the hot melt adhesive composition on the substrate by a non-contact application method.

Description

MODE FOR CARRYING OUT THE INVENTION

[0020] Hereinafter, various embodiments of the present invention will be described. Various distinctive features shown in the following embodiments can be combined with each other. In addition, an invention can be established independently for each of the distinctive features.

1. Hot Melt Adhesive Composition

[0021] A hot melt adhesive composition according to one embodiment of the present invention comprises a styrene-based block copolymer, a tackifier, and a plasticizer.

(Styrene-Based Block Copolymer)

[0022] The styrene-based block copolymer is a styrene-butadiene block copolymer, and the butadiene portion thereof is partially hydrogenated. As the styrene-butadiene block copolymer having its butadiene portion partially hydrogenated, styrene-butadiene-butylene-styrene block copolymer (SBBS) can be mentioned.

[0023] The butadiene portion of the styrene-butadiene block copolymer is preferably hydrogenated by 20 mass % to 90 mass %, more preferably by 30 mass % to 80 mass %.

[0024] The weight average molecular weight of the styrene-butadiene block copolymer is not particularly limited. Here, for example, the weight average molecular weight is preferably 30,000 to 500,000, more preferably 60,000 to 300,000. The weight average molecular weight can be obtained by gel permeation chromatograph (GPC) method.

[0025] The styrene content of the styrene-butadiene block copolymer is preferably 5 to 50 mass %, more preferably 10 to 40 mass %. When the styrene content is in such range, moderate adhesive strength and holding strength can be realized with respect to the adherend. The styrene content can be measured by the method described in JIS K6383.

[0026] Regarding the styrene-based block copolymer, one kind of a styrene-based block copolymer can be used as an adhesive, or two or more kinds of styrene-based block copolymers having different styrene content or weight average molecular weight can be blended and used suitably. That is, by using two or more kinds of the styrene-based block copolymers in combination, the melt viscosity during application of the adhesive can be made low for example, and the viscosity during application can be controlled so that processing is easy. In addition, when two or more kinds of the styrene-based block copolymers are used in combination, it is also preferable in terms of adhesive property, such as the ability to adjust adhesive strength and holding strength of the adhesive.

(Tackifier)

[0027] There is no particular limitation regarding the tackifier. Here, the tackifier is preferably a petroleum resin. As the petroleum resin, for example, C9 petroleum resin, hydrogenated C9 petroleum resin, C5 petroleum resin, alicyclic petroleum resin, alicyclic/aromatic petroleum resin, terpene resin, rosin resin, rosin ester resin, terpene-phenol resin, alkyl phenol resin and the like can be mentioned. Among these, petroleum resin is preferably at least one selected from the group consisting of C5 petroleum resin, C5C9 petroleum resin, and hydrogenated C9 petroleum resin. Further, hydrogenated C9 petroleum resin is most preferable. This is since degradation due to exposure to direct sunlight (ultraviolet ray) is small even when the adhesive tape is used outdoors.

[0028] The content of the tackifier with respect to 100 parts by mass of the styrene-based block copolymer is preferably 65 to 190 parts by mass, more preferably 80 to 150 parts by mass, and further preferably 100 to 150 parts by mass. When the content is in such range, moderate adhesive strength and holding strength with respect to the adherend can be realized. The content of the tackifier is, particularly for example, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, or 190, and can be in the range between the two values exemplified herein.

(Plasticizer)

[0029] A hot melt adhesive composition according to one embodiment of the present invention comprises a plasticizer. In the hot melt adhesive composition, the content of the plasticizer with respect to 100 parts by mass of the styrene-based block copolymer is 0.1 to 24 parts by mass, preferably 1 to 20 parts by mass, and further preferably 5 to 15 parts by mass.

[0030] Here, as the plasticizer, phthalic acid ester-based plasticizer is preferable since it has superior compatibility with the styrene-based block copolymer and thus can achieve plasticizing effect with small amount. As the phthalic acid ester-based plasticizer, DINA (diisononyl adipate), DEHP (di-(2-ethylhexyl)phthalate), DBP (dibutyl phthalate), BBP (butyl benzyl phthalate), DINP (diisononyl phthalate), DIDP (diisodecyl phthalate), and DNOP (di-n-octyl phthalate) can be mentioned. Here, use of phthalic acid esters other than DINA require caution since it can be regulated under regulations such as REACH (Registration, Evaluation, Authorization, and Restriction of Chemicals). However, DINA is not subjected to such regulations, and thus it is preferably used.

(Additive)

[0031] A hot melt adhesive composition according to one embodiment of the present invention can contain various additives such as inorganic filler, modifier, stabilizer, antioxidant, UV absorber and the like if necessary, to an extent that it does not interfere with the effect of the present invention.

2. Adhesive Tape

[0032] A adhesive tape according to one embodiment of the present invention comprises a porous substrate, and an adhesive layer provided on the porous substrate.

[0033] The adhesive tape preferably has an adhesive strength measured in accordance with JIS 20237 “10. adhesive strength” of 1.5 N/cm or more, more preferably 2.0 N/cm or more. The adhesive strength is preferably 8 N/cm or lower, more preferably 6 N/cm or lower. When the adhesive strength is in such range, while the adhesive tape would adhere to the adherend well, it is also easy to unroll the substrate when it is rolled into a tape.

[0034] The adhesive tape preferably has a holding strength measured in accordance with JIS 20237 “13. holding strength” of 10 min or more, more preferably 20 min or more. The holding strength is preferably 100 min or less, more preferably 80 min or less. When the holding strength is in such range, while the adhesive tape would have sufficient holding strength, it is also easy to handle the adhesive tape when it is rolled into a tape.

(Porous Substrate)

[0035] The porous substrate is not particularly limited so long as it is a substrate made from porous material. Here, nonwoven fabric is preferable in terms of superior mechanical strength such as tensile strength and low cost.

(Adhesive Layer)

[0036] The adhesive layer comprises the hot melt adhesive composition. The weight per unit area of the adhesive layer is not particularly limited, and is, for example, 10 to 100 g/m.sup.2. When the weight per unit area is too small, the adhesive property would be insufficient, and when the weight per unit area is too large, applying property can degrade.

3. Manufacturing Method of Adhesive Tape

[0037] A manufacturing method of adhesive tape according to one embodiment of the present invention comprises a step to apply the hot melt adhesive composition onto a substrate.

[0038] There is no particular limitation regarding the application method. Here, it is preferable to melt and knead the raw material of the adhesive with heating, and to apply the adhesive by hot melt method, and is further preferable to apply the adhesive by non-contact application method.

[0039] As an example of non-contact application, a cross coater (available from ITW Dynatec K.K) can be mentioned. In general, when an adhesive is directly applied onto a substrate such as a nonwoven fabric, the adhesive seeps into the substrate, and the adhesive property significantly decrease. When the cross coater is used, adhesive can be prevented from seeping into the substrate when the adhesive is applied onto the nonwoven fabric. Therefore, deterioration of the adhesive property hardly occur, which is preferable.

Example

[0040] Hereinafter, the present invention will be explained in detail with reference to the Examples. Here, these examples are merely an exemplification, and shall not limit the scope of the invention.

[0041] An adhesive composition was applied on the substrate shown in Table 1 and Table 2, so that the weight per unit area would be 60 g/m.sup.2 using a non-contact application method, thereby forming an adhesive layer to prepare an adhesive tape for evaluation. As the adhesive composition, as shown in Table 1, tackifier and plasticizer (DINA, available from New Japan Chemical Co., Ltd., SANSO CIZER DINA), antioxidant (available from BASF SE, Irganox 1010), UV absorber (available from BASF SE, TINUVIN P) were added to 100 styrene-based block copolymer, and the mixture was kneaded at 150° C. to obtain a molten adhesive. The adhesive thus obtained was applied using a cross coater to obtain an adhesive layer. Here, the stitch bond nonwoven fabric is a porous substrate, and the PET film is a non-porous substrate.

[0042] Each of the components shown in Table 1 and Table 2 are as follows.

SBBS: Asaprene N521, available from Asahi Kasei Corp.
SIS: Quintac 3421, available from Zeon Corporation
C5 petroleum resin: Quintone R100, available from Zeon Corporation
C5C9 petroleum resin: Quintone 5195, available from Zeon Corporation
hydrogenated C9 petroleum resin: Arkon P-100, available from ARAKAWA CHEMICAL INDUSTRIES, LTD.
terpene phenol: YS Polystar T100, available from YASUHARA CHEMICAL CO., LTD.

<Unwinding of Adhesive Tape>

[0043] Unwinding of the adhesive tape was evaluated as follows. The substrate coated with the adhesive was rolled onto a 3-inch diameter paper tube, cut into 20 mm width, and then the tape substrate was pulled out by hand from the resulting adhesive tape roll. The following criteria were used for evaluation. The results are shown in Table 1 and Table 2.

A: The tape substrate could be pulled out.
B: Force necessary for pulling out the tape substrate was too large, and the tape substrate could not be pulled out.

<SUS Adhesive Strength>

[0044] Peel adhesive strength at 180° with respect to SUS plate was measured in accordance with JIS 20237 “10. adhesive strength”. The results are shown in Table 1 and Table 2.

<Holding Strength>

[0045] Holding strength was measured in accordance with JIS 20237 “13. holding strength”. SUS plate was used as the adherend, and the adhering area of the adhesive tape was set to 25 mm×25 mm. The measurement temperature was 60° C., load was 1 kg, and the time required for the weight to drop was measured. The results are shown in Table 1 and Table 2.

TABLE-US-00001 TABLE 1 (unit: parts by mass) Example 1 2 3 4 5 6 7 adhesive styrene-based SBBS Asaprene N521 100 100 100 100 100 100 100 composition block copolymer SIS Quintac 3421 tackifier C5 petroleum resin Quintone R100 100 C5C9 petroleum resin Quintone S195 100 hydrogenated C9 Arkon P-100 100 80 150 100 100 petroleum resin plasticizer DINA MONOCIZER W-242 10 10 10 1 20 10 10 antioxidant Irganox 1726 3 3 3 3 3 3 3 UV absorber JF-77 1 1 1 1 1 1 1 substrate stitch bond nonwoven used used used used used used used fabric PET film weight per unit area of adhesive g/m.sup.2 60 60 60 60 60 60 60 unwinding of adhesive tape — A A A A A A A SUS adhesive strength N/cm 2.5 1.8 2.8 2.0 2.3 2.7 2.3 holding strength min (with respect to 20 25 11 35 11 18 19 SUS plate, 60° C.)

TABLE-US-00002 TABLE 2 (unit: parts by mass) Comparative Example Reference Example 1 2 3 4 5 6 1 adhesive styrene-based SBBS Asaprene N521 100 100 100 100 100 composition block SIS Quintac 3421 100 100 tackifier C5 petroleum resin Quintone R100 C5C9 petroleum resin Quintone S195 100 100 hydrogenated C9 Arkon P-100 100 200 60 100 100 petroleum resin plasticizer DINA MONOCIZER W-242 30 10 10 10 10 antioxidant Irganox 1726 3 3 3 3 3 3 3 UV absorber JF-77 1 1 1 1 1 1 1 substrate stitch bond nonwoven used used used used used used fabric PET film used weight per unit area of adhesive g/m.sup.2 60 60 60 60 60 adhesive 60 unwinding of adhesive tape — A A A A A was too B SUS adhesive strength N/cm 2.8 1.8 3.5 1.2 1.8 hard and 8 holding strength min (with respect to could not SUS plate, 60° C.) 2 0 5 28 0 be applied >1440