JPS608717B2 - Water-based emulsion type adhesive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a water-based emulsion type product that has good adhesive feeling (tack), is non-staining to the surface to which it is applied, and also has good adhesion to non-smooth surfaces. The present invention relates to an adhesive composition, and an adhesive tape, sheet, or film using the composition.

Conventional aqueous emulsion-type adhesive compositions containing natural rubber latex as a main component have the drawbacks of insufficient tackiness and insufficient adhesion to non-smooth application surfaces due to the high molecular weight of the latex. The reality is that it is only used in some packaging materials where adhesive surfaces are bonded together.

In addition, attempts have been made to add low softening point tackifying resins or softeners to the latex in order to compensate for the tackiness and insufficient adhesion to non-smooth application surfaces. If the material is porous like paper, the resin and softener may bleed through over time, or the adhesive may bleed into the sides of the tape. There is a problem that the surface to which it is applied is contaminated, and an improvement is desired. In view of the drawbacks of the prior art, the inventors of the present invention have conducted intensive studies on water-based emulsion-type adhesive compositions that contain natural rubber latex as a main component and do not have the above-mentioned drawbacks. Recognizing that the above-mentioned drawbacks can be overcome by using depolymerized natural rubber latex having rubber viscosity,
This is what completed the present invention.

That is, the present invention uses as a main component a mixed natural rubber latex of a depolymerized natural rubber latex and a natural rubber latex, in which the viscosity of the rubber component of the depolymerized natural rubber latex is about 1 to 10 poise in a 5% toluene solution. An aqueous emulsion adhesive composition is provided.

According to the present invention, by using depolymerized natural rubber latex, the cohesive force of the adhesive composition can be appropriately reduced and fluidity can be imparted, thereby providing a good adhesive feeling and being able to be applied to uneven surfaces. Accordingly, it is possible to obtain an aqueous emulsion type adhesive composition which has good adhesive strength and does not contaminate the surface to which it is applied.

The depolymerized natural rubber latex used in the present invention can be obtained by depolymerizing natural rubber latex by a conventional method, and a typical example thereof is the depolymerization method described for use in the Examples below. .

The viscosity of the rubber component of the depolymerized natural rubber latex was determined to be approximately 1 to 10 poise in a 5% toluene solution (BH type rotational viscometer rotor No. 1, rotation speed 1 p.m, temperature 3.
If it is less than about 1% poise, the depolymerized natural rubber latex will have poor heat resistance, weather resistance, and properties, and will not have sufficient cohesive strength as an adhesive, and if it is about 10 poise or more, it will not be sufficient. This is undesirable because it does not give a sticky feeling. The ratio of depolymerized natural rubber latex to unmodified natural rubber latex must be approximately 2% by weight or more in terms of solid content, and if it is less than this, sufficient adhesiveness will be obtained. This is undesirable because it does not provide the desired results. When producing an aqueous emulsion-type adhesive composition mainly composed of a natural rubber latex containing the depolymerized natural rubber latex, the emulsion-formed adhesive resin, that is, the adhesive resin emulsion, is mixed with the mixed natural rubber latex 10. 5 to 1 part by weight of
It is preferable to add 5 parts by weight.

If the resin emulsion is outside this range, it will be difficult to obtain sufficient adhesive strength. Examples of the tackifying resin used in such an emulsion include polyterbene resins and aliphatic hydrocarbon resins, but those having a softening point in the range of 40 to 150°C are preferred. Furthermore, low molecular weight synthetic rubbers as softeners, or compounding agents such as anti-aging agents, stabilizers, and coloring pigments can be added in required amounts. The adhesive composition thus obtained can be used in paper materials such as kraft paper, Japanese paper, crepe paper, synthetic paper, fabrics such as woven fabric, knitted fabric, non-woven fabric, other various plastic films or sheets, rubber and Plastic foam film or sheet, aluminum foil, metal foil such as stainless steel foil, support tape such as cellophane,
To provide an adhesive tape, sheet or film which is coated on the entire surface or part of the sheet or film and dried, and has excellent tackiness and adhesion to an uneven application surface.

Next, examples of the present invention will be shown.

The part in the middle of the text is the weight part. The method for producing the depolymerized natural rubber latex used in the following examples, and the method for measuring the viscosity of the rubber component and each characteristic are as follows.

How to make Urokoungo natural rubber latex Natural rubber latex (
Put 10 parts of cumene hydroperoxide (solid content 50%) into a reaction vessel, add 0.5 part of sulfated fatty acid (solid content 70%) while stirring in the presence of oxygen, and then add 10 parts of cumene hydroperoxide (solid content 70%).
% toluene solution) to raise the temperature of the reactant,
When the temperature reached 40oo, tetraethylenebentamine (5
0% aqueous solution) is added, and the reaction system is further heated and kept at 50°C, and reacted in that state for 3 hours to obtain depolymerized natural rubber latex.

Viscosity of the rubber content of the depolymerized natural rubber latex The depolymerized natural rubber latex was cast on a glass slope and air-dried for two hours.
The obtained rubber film was dissolved in toluene to make a 5% toluene solution, and the viscosity (CPS) of this solution was measured using a BH-type rotational viscometer (Rotator No. 1, rotation speed 1 and p.
．． m).

Measuring method of properties [Adhesive strength: According to JIS Z1523.

Others Cohesive force: A sample tape was attached to a stainless steel plate polished with #280 sandpaper so as to have an adhesion area of 25 x 25 skins, and 2K9 pressure was applied. Make a test specimen by crimping it with a roller, fix the stainless steel plate vertically, and apply 1kg to the edge of the tape.
A load of 100 ml was applied and the tape was left in an atmosphere of 40 oo, and the time until the tape peeled off and fell was measured. Shiichi Tack: J
．． In the DOW method, a tape sample of a certain length is fixed on a slope with an angle of 30 degrees, and steel balls of 32 different sizes from 1'32 inches to 1 inch are rolled on the tape sample from a certain height. No. of the maximum diameter that stops. It shows a sticky feeling.

8. Aging property: The test specimen used in the cohesive force measurement method was left in an atmosphere of 100:00 for 60 minutes.

The difference between the cohesive force of the test piece before standing and the cohesive force of the test piece after standing was calculated using the following formula. Cohesive force XI before leaving the cohesive car after leaving.

○Cohesive force 90 degree constant load peeling before leaving: Attach the sample tape to the stainless steel slope polished with #280 sandpaper so as to have an adhesion area of 25 x 5 gunwales and press it with a 2K9 pressure roller. A stainless steel plate is fixed horizontally, a load of 10 M is applied to the end of the tape, and the tape is left in an atmosphere of 40 qo to measure the time until the tape peels off and falls.

Example 1 Depolymerized natural rubber latex with a viscosity of 7 cps in a 5% rubber solution in toluene, unmodified natural rubber latex (
50% solid content), an aliphatic hydrocarbon resin emulsion with a softening point of 60 qo (solid content 40%), and Polysof.

A water-based emulsion type adhesive composition is obtained by blending a lotus root emulsion (average molecular weight: 29,000, solid content: 50%) as shown in Table 1. This adhesive composition was applied to Japanese paper with a thickness of 60 mm so that the thickness after drying was 40 mm.
After drying for 3 minutes, sample No. Obtain adhesive tapes 1 to 6.

Its properties are shown in Table 1. Table 1 As is clear from Table 1, sample No. 1 and systems using a mixed natural rubber latex of depolymerized natural rubber latex and unmodified natural rubber latex (sample Nos. 2 to 3) have suitable adhesive strength and tackiness (tack), Moreover, it is notable that it has excellent adhesive strength even in a 90 degree constant load peel adhesion test.

However, systems based mainly on unmodified natural rubber latex (
Sample No. Examples 4 to 6) had insufficient adhesion and tackiness, and in addition, in a 90 degree constant load peel adhesion test, the adhesive strength was so low that peeling rapidly progressed as soon as a load was applied. In addition, sample No. in Table 1. 5 to 6 are
In order to obtain a certain adhesive strength, a polyisoprene rubber emulsion as a softening agent component was added to the 20-3 base portion, which was larger than that of the other samples. The sample was attached to a BA-finished stainless steel plate and 6yo x 80% R. Day. When the sample tape was peeled off after being left for 4 hours in the presence of a stainless steel plate, it was found that the adhesive adhered to the surface of the stainless steel plate, contaminating the applied surface.
No. No such contamination was observed in samples 1 to 3). As is clear from the above examples, the aqueous emulsion type adhesive composition of the present invention can achieve suitable adhesive strength, moderate cohesive strength, and good adhesive strength by using depolymerized natural rubber latex having a specific rubber viscosity. Good adhesion and excellent 90%
The fact that constant load peel adhesive strength can be obtained is remarkable.

Claims (1)

[Scope of Claims] 1. The main component is a mixed natural rubber latex of depolymerized natural rubber latex and natural rubber latex, in which the viscosity of the rubber component of the depolymerized natural rubber latex is about 1 to 10 poise in a 5% toluene solution. Aqueous emulsion type adhesive composition. 2. The aqueous emulsion type adhesive composition according to claim 1, wherein the proportion of the depolymerized natural rubber latex in the mixed natural rubber latex is about 20% by weight or more in terms of solid content.