JPH05171123A - Natural rubber-tacky agent composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition suitable as a tacky agent for a natural tacky tape, having excellent tack, cohesive force, hue, etc., comprising a transparent plastic film as a substrate by blending a natural rubber with a hydrogenated coumarone resin as a tacky agent. CONSTITUTION:100 pts.wt. natural rubber is blended with 5-50 pts.wt. hydrogenated coumarone resin to give the objective composition. The coumarone-based hydrogenated resin is usually not used alone but utilized together with a tackifying resin such as rosin-based resin, terpene-based resin or 5C-based petroleum resin having excellent compatibility with natural rubber or their hydrogenated resin. When the hydrogenated coumarone resin and the other trackifying resin are used together, 100 pts.wt. natural rubber is preferably blended with 30-150 pts.wt. total amounts of both the hydrogenated coumarone resin and the other tackifying resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a natural rubber-based pressure-sensitive adhesive composition, and more specifically, a natural rubber-based pressure-sensitive adhesive using a coumarone hydrogenated resin as a tackifying resin and having excellent adhesive strength, cohesive strength, hue and the like. Agent composition.

[0002]

2. Description of the Related Art Tackifying resins are
Along with the rubber elastic body, it is one of the important components constituting the adhesive. By adding the tackifying resin to the rubber elastic body, the tack and the adhesive force are increased. In particular, it is known that the tack becomes large when the SP values (solvability parameters) of the rubber elastic body and the tackifying resin are similar.

As a tackifying resin used in a natural rubber-based pressure-sensitive adhesive, a rosin-based resin, in consideration of compatibility,
Terpene-based resins, C5-based petroleum resins, or hydrogenated resins of these are mainly used, and in order to obtain the required adhesive strength, a considerable amount of compounding parts is necessary with respect to the natural rubber.

On the other hand, as a tackifying resin for a pressure sensitive adhesive containing a thermoplastic elastomer typified by SIS (styrene-isoprene-styrene block copolymer) as a main polymer, in addition to the above-mentioned tackifying resins, C9 resin, coumarone Resins are often used because of their good compatibility.

Conventionally, coumarone resin and coumarone hydrogenated resin have been used for improving tackiness of polymers such as SIS and SBR which contain an aromatic ring in the molecule or tackifying resin of acrylic pressure sensitive adhesive due to their compatibility. , It is not used due to its poor compatibility with natural rubber alone.

By the way, when a tackifying resin having a good compatibility is blended with a natural rubber-based pressure-sensitive adhesive, the tackiness is good, but the tackiness is slightly insufficient.
In fields where cohesive strength is required, improvement of these properties is required.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a natural rubber-based pressure-sensitive adhesive composition excellent in adhesive strength, cohesive strength, hue and the like. Another object of the present invention is to provide a natural rubber-based pressure-sensitive adhesive composition suitable as a pressure-sensitive adhesive for a natural rubber-based pressure-sensitive adhesive tape having a transparent plastic film as a base material.

As a result of intensive studies, the present inventors have found that by adding coumarone hydrogenated resin as a tackifying resin to natural rubber, the tackiness can be greatly improved without hindering tackiness and aggregation. It has been found that the strength and hue are also good.

The coumarone hydrogenated resin, when used in combination with another tackifying resin which is generally compatible with natural rubber, has an excellent balance of tack, adhesive strength and cohesive strength, and the adhesive strength is remarkably improved. An adhesive composition can be provided. The present invention has been completed based on these findings.

[0010]

The gist of the present invention is that a coumarone hydrogenated resin is contained in a proportion of 5 to 50 parts by weight with respect to 100 parts by weight of natural rubber, as a natural rubber-based pressure-sensitive adhesive composition. Is.

The present invention will be described in detail below. In the present invention, natural rubber is used as the base polymer, and the coumarone hydrogenated resin is contained in a ratio of 5 to 50 parts by weight based on 100 parts by weight of the natural rubber.

The coumarone hydrogenated resin is not usually used alone, but it is an adhesive of rosin resin, terpene resin, C5 petroleum resin, or hydrogenated resin thereof having good compatibility with natural rubber. Used in combination with the applied resin. When using coumarone hydrogenated resin in combination with other tackifying resins, natural rubber 1
It is used in a proportion of 30 to 150 parts by weight in total with respect to 00 parts by weight.

If the blending ratio of the coumarone hydrogenated resin is less than 5 parts by weight, the effect of improving the adhesive force, cohesive force and hue is small, and if it exceeds 50 parts by weight, the tack is rapidly reduced.
Further, when the total amount of the coumarone hydrogenated resin and the other tackifying resin is less than 30 parts by weight or exceeds 150 parts by weight, tack, adhesive strength and cohesive strength are insufficient.

Since the coumarone hydrogenated resin is hydrogenated, the hue of the pressure-sensitive adhesive composition to which it is added is beautiful.
Therefore, the pressure-sensitive adhesive composition of the present invention is particularly suitable as a pressure-sensitive adhesive for a pressure-sensitive adhesive tape having a transparent plastic film as a base material. As a transparent plastic film,
For example, cellophane, biaxially oriented polypropylene film, etc. can be mentioned.

If necessary, the natural rubber-based pressure-sensitive adhesive composition of the present invention may contain a softening agent, an antioxidant, a filler, a cross-linking agent and the like. Examples of the softening agent include polybutene, polyisobutylene, process oil, and naphthenic oil. Examples of the antiaging agent include, for example,
General-purpose phenol and amine stabilizers are preferred. Examples of the filler include titanium white, zinc white, calcium carbonate, clay, talc, pigment, carbon black and the like. Examples of the cross-linking agent include thiuram-based, phenol-based, isocyanate-based and the like.

[0016]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, the number of parts in Examples and Comparative Examples is based on weight unless otherwise specified.

[Examples 1 to 4 and Comparative Examples 1 and 2] 100 parts by weight of natural rubber (RSS # 1) was mixed with various tackifying resins shown in Table 1 to prepare adhesive compositions. .. Biaxially oriented polypropylene film as base material (thickness 40μ
m), a toluene solution of the pressure-sensitive adhesive composition prepared above was applied by a coater and dried to give a dry thickness of 25 μm.
m adhesive layer was formed. The tack, the adhesive force and the holding force of the obtained adhesive tape were measured. The results are shown in Table 1.

The methods for measuring the physical properties are as follows. Tack (J. Dow): JIS Z-0237 SP adhesive strength: JIS K-0237 (SP; stainless steel plate) SP holding power: JIS K-0237

[0019]

[Table 1]

(Footnote) RSS # 1: Natural rubber Super ester A-100: Disproportionated rosin ester,
Arakawa Chemical Co., Ltd. YS resin PX1000: Terpene resin, Yasuhara Chemical Co., Ltd. Quinton A-100: C5 series resin, Nippon Zeon Co., Ltd. Escrystal A-100: Coumaron hydrogenated resin, Nippon Steel Chemical Co., Ltd.

Evaluation Comparative Example 1 is a compounding formulation consisting of 40 parts of a terpene resin and 60 parts of a C5 resin as a tackifying resin, while Examples 1 to 3 have 5 parts of the C5 resin. It is a compounding recipe in which ˜50 parts of coumarone hydrogenated resin is replaced.

Comparative Example 2 is a compounding formulation using a disproportionated rosin ester instead of the terpene resin of Comparative Example 1,
In contrast, in Example 4, 10% of disproportionated rosin ester was used.
And 20 parts of C5-based resin, and 20 parts of coumarone hydrogenated resin was used instead.

As is clear from Table 1, in Comparative Example 1 and Examples 1 to 3, the tack was decreased with an increase in the addition amount of the coumarone hydrogenated resin, but the SP adhesive strength was significantly improved. Be done. In Comparative Example 2 and Example 4, by reducing the total number of tackifying resins by 10 parts, a significant increase in SP adhesive strength was obtained without significantly reducing tack. Further, the cohesive force of each example is also improved as compared with each comparative example.

In the examples, all of the compounding examples using the tackifying resin having a softening point of 100 ° C. are shown, but when a resin having a lower softening point is used, the total number of tackifying resins is increased. Similar results are obtained with the formulation and, conversely, when a resin with a higher softening point is used.

Further, as is clear from Example 3, when the number of coumarone hydrogenated resin increases beyond 50 parts, the tack is significantly lowered, and therefore, as an adhesive which is required to be practical at low temperature. Unsuitable. Furthermore, these adhesive tapes of Examples 1 to 4 were excellent in transparency because the hue of the adhesive layer was good.

[0026]

EFFECTS OF THE INVENTION According to the present invention, a coumarone hydrogenated resin is contained as a tackifying resin to provide a natural rubber-based pressure-sensitive adhesive composition excellent in tackiness, cohesion and hue.

The natural rubber adhesive composition of the present invention comprises
(1) Adhesive force is significantly improved, (2) Adhesive force can be improved without sacrificing tack by reducing the total amount of tackifying resin, (3) To obtain the same adhesive force, Since the total amount of tackifying resin used can be reduced,
Cost reduction, and (4) Coumaron hydrogenated resin is a hydrogenated product, so the adhesive is neat and advantageous for transparent products using transparent plastic film substrates.
And the like.

Claims (1)

[Claims] 1. A natural rubber-based pressure-sensitive adhesive composition comprising a coumarone hydrogenated resin in an amount of 5 to 50 parts by weight based on 100 parts by weight of natural rubber.