JPS6245273B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a pressure-sensitive adhesive tape for binding various undried vegetables, fresh flowers, etc. (Prior Art) An important property required of adhesive tapes for binding undried vegetables and fresh flowers is that they exhibit only extremely weak adhesion to the objects to be bound, but when the adhesives are bonded together, It shows high self-adhesion. In order to create an adhesive composition that satisfies these properties, the present inventors have developed an adhesive composition containing, based on 100 parts by weight of the elastomer, about 3 to 40 parts by weight of a polymer compatible with the elastomer and about 5 to 30 parts by weight of a tackifier. proposed a composition containing parts by weight as the main ingredient (patent application 1983-
No. 2671, Japanese Unexamined Patent Publication No. 54-96539). Adhesive tapes coated with such compositions are useful for binding fresh vegetables and fresh flowers, but they exhibit the disadvantage of slipping and peeling when the objects to be bound undergo volumetric expansion. For example, when raw vegetables are tied together, they are often soaked in water while still tied to maintain their freshness during the distribution process. When the water content of the raw vegetables increases due to water immersion, the raw vegetables expand in volume, and this causes a force to resist the bonding force at the bonded portions of the tapes, eventually leading to peeling. In the worst case, the joints of the tapes will completely peel off and the objects to be bound will fall apart. Therefore, the adhesive must have excellent creep resistance under a constant load in order to resist expansion due to moisture absorption of the material to be bound. Furthermore, when binding raw vegetables with a binding machine using this type of adhesive binding tape, in order to bind them firmly, they must be bound against a certain amount of repulsive force, so the adhesive tape must be bound against each other. The joining must be completed instantly. (Objective of the Invention) An object of the present invention is to provide an adhesive tape with improved creep resistance for binding raw vegetables, fresh flowers, etc. Specifically, the present invention has a weak adhesive force that does not cause damage to the objects to be bound, the bond between the adhesives is instantly completed, and once the objects are bound, the objects will not repel. The purpose of the present invention is to provide an adhesive tape that does not loosen when twisted and can withstand sustained expansion force due to moisture absorption after binding. (Property Measuring Method) In order to quantitatively evaluate the physical properties that these adhesive tapes should possess, the present inventors used a unique measuring method.The physical properties used in this specification are as follows. Define. Initial adhesive strength is measured by touching the smooth tip of a metal rod with a diameter of 5 mm to the surface of the adhesive for 1 second with a load of 100 g under conditions of 20°C and 65% relative humidity.
The resistance value when pulled apart at a speed of 10 mm per second (ASTM Special Technical Publication No.360
reference). Adhesive strength is based on the method for measuring adhesive strength of JIS-Z.1522 (cellophane adhesive tape).A 20 mm wide adhesive tape is pressed onto a stainless steel panel with a roller weighing 2 kg, and the loose part is removed. This is the resistance value when the panel is bent 180 degrees to the panel surface and pulled at a pulling speed of 300 mm/min. Self-adhesive strength refers to a piece of adhesive tape that is 20 mm wide and about 15 cm long, and the adhesive is pasted to the center of the tape over a length of about 25 mm so that the edges of the opposing tapes do not shift. This is the resistance value when the adhesive is crimped with a 1 kg roller, and then the ends where the adhesive is not bonded are immediately pulled apart in opposite directions and pulled at a speed of 300 mm/min. Self-adhesion retention is used to evaluate creep resistance.Take a piece of adhesive tape 20mm wide and 15cm long, and place the adhesives facing each other over a length of about 25mm in the center. Paste the tape edges so that they do not shift, fix one of the two ends where the adhesive is not joined, and attach a weight of 500 g to the other free end.
1 under conditions of 20℃ and 65% relative humidity.
This refers to the length of the joint that peels off after being left for a period of time. (Structure of the Invention) The adhesive tape for binding fresh vegetables, fresh flowers, etc. according to the present invention is made of a styrene-isoprene-styrene block copolymer, or exceeds 80 parts by weight and up to 100 parts by weight of the block copolymer. and less than 20 parts by weight of other elastomers, 20 to 150 parts by weight of tackifier, and 0 to 100 parts by weight of additives.
It is characterized in that an adhesive composition consisting of 150 parts by weight is applied to one side of a water-resistant substrate. In the present invention, the elastomer is not only a styrene-isoprene-styrene block copolymer but also -A-B-A (where A and B each represent a polymer block) such as a styrene-butadiene-styrene block copolymer. A block copolymer having the general structure of natural rubber and molecular weight
600,000 or more butyl rubber, such as butyl #268 manufactured by Etsuso Standard Oil Co., Ltd., isobutylene rubber,
It may also contain one or more polymers selected from synthetic rubbers such as polyisoprene. Advantageously, the elastomer contains at least 80 parts by weight of styrene-isoprene-styrene block copolymer (hereinafter referred to as SIS).
is simply written as “department”). If the amount of components other than SIS in the elastomer is 20 parts or more, self-adhesion and self-adhesion retention will decrease. Tackifiers include polyterpenes, rosin esters, and petroleum resins with a softening point of 100°C or higher (e.g. Quinton A100, D100, D200, C100, C200S).
Synthetic polyterpenes, such as Alcon P100,
Aliphatic cyclic hydrocarbon resins such as P115, P125,
Hydrogenated hydrocarbon resins such as Escolets 5300 and 5320, unsaturated hydrocarbon resins such as Escolets 1202, isobrene hydrocarbon resins such as Escolets 1304, 1310 and 1315, and Takku Ace.
Examples include hydrocarbon resins such as A100).
These tackifiers can be used alone or in combination for a total of 20~
150 copies will be used. If it exceeds this range, the self-adhesion and creep resistance will deteriorate, and the function as a binding tape will be impaired. Additives are used to adjust appropriate cohesiveness and self-adhesion in adhesives, such as calcium carbonate,
Zinc white, titanium oxide, vegetable oils and modified products thereof (e.g. castor oil, rapeseed oil, soybean oil, phactis, etc.), paraffinic or aromatic process oils (e.g. Flexon 765, 110, 112 and 876)
etc.), polybutene and liquid polyisobutylene,
One or more types of polyterpenes with a softening point of 20°C or less. If the amount of additive exceeds 150 parts, the balance between cohesive force and self-adhesive force will not be maintained, and the initial adhesiveness will become particularly poor, making it impossible to expect instantaneous and firm bonding. Among these additives, it is desirable that the amount of liquid additives is 20 parts or less in consideration of the cohesive force balance. As the water-resistant base material, a film such as polypropylene, polyethylene, unplasticized polyvinyl chloride, or polyester can be used, and the thickness thereof is preferably about 20 to 60 μm, and it cannot be tied by machine or hand. In addition to workability, it is better to increase or decrease the amount further for reasons such as preventing damage to vegetables. In addition, the product value can be further increased by coloring the base material as desired with a coloring agent or printing, dividing it into categories according to the type of vegetables, etc., or displaying the product name, production area name, collection date, etc. . Next, the present invention will be explained in detail based on the drawings. A pressure-sensitive adhesive composition layer 2 is coated on one side of the base material 1 . The adhesive composition is prepared by kneading the various components with a Banbury mixer or rubber kneading roll, stirring and dissolving them in a solvent such as hexane or a mixture of hexane and toluene, and preparing an adhesive liquid with a solid content of 10 to 40% by weight. do. When using a liquid additive, the liquid additive may be added at the stage of dissolution with a solvent. The adhesive composition thus prepared is applied to one side of the base material 1 by a conventional method, dried, and wound up to form the adhesive tape 3. Advantageously, the applied layer of adhesive has a dry thickness of about 5 to 30 microns. When binding raw vegetables 4, etc., for example, if you use a long adhesive tape wound into a roll, it will be easy to bind by machine regardless of the size of the bundle.
On the surface in contact with vegetables, the adhesive tape 3 has weak adhesion due to its adhesive composition layer 2, and strong self-adhesion at both ends 3a. (Effect of the invention) The adhesive tape according to the invention has the following characteristics:
As shown in the table. Table 1 Initial adhesive strength (g/5mm diameter) 300-700 Adhesive strength (g/20mm width) 200-700 Self-adhesion strength (g/20mm width) 1500 or more Self-adhesion holding power (mm/500g/hour) 0-5 Among general commercially available tapes, the corresponding characteristic values of packaging tapes that particularly require creep resistance of the adhesive are measured, and the results are shown in Table 2.

[Table] As is clear from Tables 1 and 2, the adhesive tape according to the present invention is significantly superior to commercially available packaging tapes in terms of self-adhesion and especially self-adhesion retention. Since the adhesive tape using the composition proposed in Japanese Patent Application No. 53-2671 has a self-adhesive holding power of 20 mm/500 g·hr or more, the self-adhesive holding power, that is, the creep resistance of the adhesive tape according to the present invention, is as follows. It is clear that the improvements have been made to a very high degree. Since the adhesive tape according to the present invention has excellent self-adhesive holding power as described above, there is no possibility that the adhesive tape for binding will shift or that the bound vegetables, etc. will slip out or fall off during transportation or other handling. Even if the bundled vegetables or the like expands, the self-adhesive parts at both ends will not peel off (that is, the bundle will not break). Furthermore, even if the adhesive tape is untied, some of the vegetables will not stick and be cut off, so even if soft leafy vegetables are tied together, they will not be damaged and their quality will not deteriorate. Furthermore, the production of the adhesive tape of the present invention does not require special materials or troublesome labor, and mass production is easy.
It is suitable for binding raw vegetables such as leafy vegetables and fruit vegetables, fresh flowers, etc., as well as for binding props of cultivated crops (plants) in gardening. Next, the present invention will be described in detail based on Examples, but the present invention is not limited thereto. Examples 1 to 14 On one side of a 40μ thick polypropylene film,
Various adhesive compositions shown in Table 3 were applied and dried to produce adhesive tapes with adhesive layers having a thickness of 20 μm. The characteristics of each adhesive tape were measured and the results are shown in Table 3.

[Table] Example 15 The adhesive composition shown in Table 4 was coated on a polyester film having a thickness of 25μ and dried to produce an adhesive tape having an adhesive layer having a thickness of 25μ. Table 4 shows the properties of the obtained adhesive tape. Example 16 On a 40μ thick unplasticized polyvinyl chloride film,
The adhesive composition shown in Table 4 was applied and dried to produce an adhesive tape with an adhesive layer thickness of 20 μm. Table 4 shows the properties of the obtained adhesive tape.

[Table] Example 17 Two types of adhesive tapes were manufactured by applying the following adhesive composition to one side of a polypropylene film.

【table】

[Table] Using these two types of adhesive tape,
I tied up 250g of spinach. At this time, the length of the tape at the joint portion was 17 mm in both cases. The tied spinach was immersed in water as it was, and the peeling of the bonded parts over time was measured. The results are shown in Table 6. In the table, tape A is a tape coated with the above-mentioned adhesive composition according to the present invention, and tape B is a tape coated with the above-mentioned pressure-sensitive adhesive composition according to the invention of Japanese Patent Application No. 53-2671.

[Table] As is clear from this table, the adhesive tape according to the present invention withstands the expansion of objects to be bound without peeling.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a perspective view, FIG. 2 is a cross-sectional view taken along the line -- in FIG. 1, and FIG. 3 is a schematic explanatory view showing the state of use. 1 is a base material, 2 is an adhesive composition layer, 3 is an adhesive tape, and 4 is vegetables.

Claims (1)

[Scope of Claims] 1 Consists of a styrene-isoprene-styrene block copolymer, or more than 80 parts by weight and up to 100 parts by weight of the block copolymer and 20 parts by weight of other elastomers.
less than 100 parts by weight of an elastomer consisting of less than 100 parts by weight,
An adhesive for binding raw vegetables, fresh flowers, etc., characterized in that an adhesive composition comprising 20 to 150 parts by weight of a tackifier and 0 to 150 parts by weight of an additive is applied to one side of a water-resistant base material. tape. 2 Initial adhesive strength 300-700g/5mm diameter, adhesive strength 200-700g/20mm width, self-adhesion strength 1500g or more/20
The adhesive tape according to claim 1, which has a width of mm and a self-adhesive holding force of 0 to 5 mm/500 g·hr. 3 In addition to the styrene-isoprene-styrene block copolymer, -A-B-A-
(wherein A and B each represent a polymer block) comprising one or more polymers selected from block copolymers, natural rubbers, and synthetic rubbers having the general structure: The adhesive tape according to item 2. 4. A patent claim in which the elastomer is a mixture of more than 80 parts by weight and up to 100 parts by weight of a styrene-isoprene-styrene block copolymer and less than 20 parts by weight of natural rubber, styrene-butadiene-styrene block copolymer, butyl rubber, or polyisobutylene. Adhesive tape according to scope 1 or 2. 5. The adhesive tape according to claim 1 or 2, wherein the tackifier is one or more of polyterpenes, rosin esters, and petroleum resins having a softening point of 100° C. or higher. 6. Claim 1 or 2, wherein the petroleum-based resin is selected from synthetic polyterpenes, aliphatic cyclic hydrocarbon resins, hydrogenated hydrocarbon resins, unsaturated hydrocarbon resins, and isoprene-based hydrocarbon resins. Adhesive tape as described in section. 7. Use one or more of the following additives: calcium carbonate, zinc white, titanium oxide, vegetable oil and its modified products, paraffinic and aromatic process oils, polybutene, liquid polyisobutylene, and polyterpenes with a softening point of 20°C or less. Claim 1
The adhesive tape according to item 1 or 2. 8 Polypropylene, polyethylene, as base material
The adhesive tape according to claim 1 or 2, which uses a film made of unplasticized polyvinyl chloride or polyester. 9. The adhesive tape according to claim 1 or 2, wherein the adhesive coating layer has a dry thickness of 5 to 30 μm.