JPS62106978A - Pressure-sensitive polyurethane adhesive tape capable of repreated use - Google Patents

Abstract

PURPOSE:To provide the titled adhesive tape capable of peeling off an adhered without failure, by using a polyol and an org. diisocyanate as raw materials and coating or impregnating fibrous materials with a polyurethane prepd. by a particular procedure. CONSTITUTION:A prepolymer having a terminal isocyanate group is prepd. by reacting one or a mixture of two or more polyols having an average number of functional groups of 2-2.6 (e.g., polypropylene glycol) with an excess of org. dissocyante (e.g, 2,4-tolylene diisocyanate). Then, said prepolymer is reacted with one or a mixture of two or more polyols wherein an average number of functional groups is 2 or more and the sum thereof with the average number of functional groups of the polyol mixture constituting said prepolymer is 4-5 to attain the equivalent ratio of NCO to OH of 0.65-1.15. The titled pressure- sensitive adhesive tape is yielded by coating or impregnating fibrous materials with the resulting polyurethane.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a pressure-sensitive adhesive material using a polyurethane resin, and particularly to a pressure-sensitive adhesive tape that can be used repeatedly.

(Prior art) Materials currently widely used as pressure-sensitive adhesives are generally made of polymer bases such as natural rubber, SBR, polychloroprene, and polyisobutylene with a plasticizer added as a softener.
Furthermore, rosin, rosin ester, coumaron indene resin, etc. are added as a tackifier.

Pressure-sensitive adhesives based on polyurethane resins have also been announced. (BP, 1.113.925. JP-A-53-31192) (Problems to be solved by the invention) A polymeric pressure-sensitive adhesive is a composition consisting of a base, a plasticizer, and a tackifier. It has poor adhesive properties and decreases in adhesive strength due to changes in composition, leading to various problems when used for a long period of time. In addition, even if the adhesive is used for a short period of time, once the adhesive surface is removed, a large amount of adherend or dirt will adhere to the surface of the adhesive, but since it is no longer necessary to remove these, the adhesive can be reused. is not possible.

Furthermore, when the tackiness of a polyurethane adhesive is increased, the strength of the ballast decreases. For this reason, once the adherend is peeled off, the adhesive layer is destroyed and reuse becomes almost impossible.

(Means for Solving the Problems) The present inventors have arrived at the present invention as a result of research to develop a double-sided pressure-sensitive adhesive tape that has strong adhesiveness and can be repeatedly reused.

That is, when producing polyurethane by the reaction of a polyol and an organic diisocyanate, the present invention uses a terminal polymer obtained by reacting one or more polyol mixtures having an average functional group number of 2 to 2.6 with an excess of an organic diisocyanate. A prepolymer having a cyanate group is combined with one or more polyols having an average number of functional groups of 2 or more, and a sum of which exceeds 4 and does not exceed 5 with the average number of functional groups of the polyol mixture that is a component of the prepolymer. This is a polyurethane pressure-sensitive adhesive tape that can be used repeatedly and is prepared by coating or impregnating a fiber material with a polyurethane obtained by reacting a mixture with an NC010H equivalent ratio of 0.65 to 115.

Examples of materials suitable for the fiber material used in the present invention include acrylic, acetate, viscose rayon, nylon,
Chemical fibers and synthetic fibers such as polyvinylidene, vinylon, polybenzoate, polyurethane, polyester, polyethylene, polypropylene, cotton, silk, wool, pulp,
These include natural fibers such as paper, inorganic fibers such as glass fiber, carbon fiber, rock wool, and ceramic fiber, and metal fibers such as iron, stainless steel, aluminum, nickel, and yMf9. The diameter of these fibers is suitably 200 microfron to 200 mm, and both long fibers and short fibers can be used.

These fibers are also used in the present invention as woven, knitted or nonwoven fabrics.

These fiber materials can be made into a single-sided adhesive tape by attaching a polyurethane layer to only one side. Furthermore, if these fiber materials are placed at the center of the thickness of the tape, the resulting double-sided adhesive tape will have smooth surfaces on both sides, and the adhesive strength on both sides will be the same. Lay the fiber material here on one side and place the fabric on that surface.
It is also possible to reproduce the surface irregularities of knitted or nonwoven fabrics. The adhesive strength of the uneven surface to the adherend can be adjusted depending on its shape. Therefore, if the smooth side of such double-sided adhesive tape is adhered to the main body, the adherend can be attached and removed any number of times without peeling off the tape from the main body.

If the surface of the tape becomes dirty with dirt or other foreign matter and its adhesive strength decreases, the adhesive strength can be restored by washing the tape with water or wiping the surface with a wet cloth to remove the foreign matter and drying it.

Components of the mixed polyol used in the present invention include the following, and one or more of them may be used as a mixture. Monools such as n-butanol, ethylene glycol monobutyl ether, propylene glycol, ethylene glycol, or addition polymerization of these with propylene oxide, ethylene oxide, or both, polyether diols such as polytetramethylene ether glycol, and ethylene glycol. , propylene glycol, 1. a-5 Polyester glycol obtained by dehydration condensation from a low molecular weight glycol such as tanediol and an organic acid such as adipic acid or phthalic acid, glycerin, trimethylolpropane, pentaerythritol, arabitol, or as an initiator. As such, propylene oxide, ethylene oxide, or the addition polymerization of both are used. Furthermore, polymer polyols obtained by polymerizing olefin monomers such as acrylonitrile and styrene in these polyols can also be used.

The organic diisocyanate used in the present invention includes 2
, 4-toluylene diisocyanate and 2.6-1ylene diisocyanate or mixtures thereof, crude toluylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, 1,5 - Aromatic diisocyanates such as naphthylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, inphorone diisocyanate,
4,4'-dicyclohexylmethane diisocyanate,
Examples include aliphatic or alicyclic diisocyanates such as inpropylidene bis(cyclohexyl isocyanate) and xylylene diisocyanate, and dimers, trimers, and carbodiimide modified products thereof.

To carry out the present invention, the average molecular weight is 200 to aooo.
, preferably from 100 to 5000, and the average number of functional groups is less than 2.6 and not less than 2 for a polyol or a mixture of two or more polyols.
H equivalent ratio 1.3 to 5, preferably 1.5 to 3
For a prepolymer having terminal incyanate groups obtained by reacting excess organic diisocyanate in the same manner as in 4,
The average number of functional groups is not less than 2, and the sum of the average number of functional groups of the polyol that is a component of the prepolymer exceeds 4 and does not exceed 5, and the average molecular weight is 200 to 8,000.
, preferably one or two of 1000 to 5000
NC010H equivalent ratio of 0.6 or more polyol mixture
5 to 115, preferably 0.75 to 1.05.

When a cloth-like fibrous material is used, by applying a mixture of prepolymer and polyol to the same thickness on both sides, a tape having the same tackiness on both sides can be obtained. Also, by applying a thin layer on one side of the fiber material to create unevenness, you can create tapes with different degrees of adhesion. Furthermore, it is also possible to use it by coating only one side.

When using a mesh-like fibrous material, place a spacer on a Teflon plate with a weir around it and place the mesh on top of it, or place the mesh away from the Teflon surface and apply the mixture of prepolymer and polyol. If you leave it to solidify after injecting it, you can create a tape that is smooth on both sides and has the same adhesiveness.

Alternatively, by placing a mesh directly on a Teflon plate and injecting a mixture of prepolymer and polyol, a pressure-sensitive adhesive tape with mesh on one side can be produced.

The reason for limiting the average number of functional groups of polyol will be explained. If the average number of functional groups of the polyol is 2 or less, it will result in insufficient cohesive force, and if it exceeds 2.6, the adhesive force will become weak, resulting in a decrease in elongation. Next, when the sum is larger than 5, the reaction product becomes too reticulated, resulting in a decrease in cohesive force and elongation, and in some cases, a decrease in adhesive force.

There are no major changes in its viscoelastic behavior, adhesion, adhesion, cohesive force, elongation, etc. over a wide temperature range, and the addition of softeners and tackifiers is not a necessary condition, so there is a risk of migration caused by them. Gana G).

In the present invention, aromatic diisocyanates are preferable in terms of reactivity, but aliphatic or alicyclic diisocyanates are used to completely prevent yellowing of the pressure sensitive adhesive due to long-term exposure. There is a need.

During the synthesis of the prepolymer or the reaction of the prepolymer with the polyol, catalysts such as dibutyltin dilaurate, cobalt naphthenate, lead octoate, triethylenediamine, triethylamine, N-cocomorpholine, etc., or benzoyl chloride, etc. It is permissible to use anti-gelling agents.

Additions of softeners, plasticizers, tackifiers, etc. that have been used in conventional pressure sensitive adhesives are not required at all to the pressure sensitive adhesive of the present invention, but may be added as long as they do not impair the properties.

Further, one of the features of the pressure sensitive adhesive according to the present invention is that it has excellent cohesive force, but in order to further improve the cohesive force, a filler may be used according to a known method.

The pressure-sensitive adhesive according to the present invention is still only a raw material mixture and has not been converted into a resin when applied to the target location (for example, on a substrate), so it can be applied as is without adding a solvent or heating. Although the viscosity is relatively low, a solvent may be added or heating may be performed to further reduce the viscosity.

(Examples) In order to explain the present invention in more detail, some examples and reference examples will be shown below. Unless otherwise specified, parts in Examples and Reference Examples are parts by weight and percentages are weight percent.

The physical property values in Examples and Reference Examples are measured as follows, and evaluated based on the test results.

Tensile strength Elongation at break according to JIS K-6301-1971 Same as above (JIS B-type hard disk) Adhesion Polyethylene disc with smooth bottom (diameter 16
．． 6 mm, thickness 4.0 inch) was gently placed on the sample surface, a load (weight) of 1 oap was applied to it, and the sample was left for 10 seconds. After removing the load, it was peeled off in a circular direction at a speed of 500 rnttr/min. This special power is expressed in Durham units with two significant figures.

The compositions of various raw materials used in Examples and Reference Examples are as follows.

a) PPG-Dial-1500 (trade name) manufactured by Mitsui Toatsu Chemical Co., Ltd., polypropylene glycol O with an average molecular weight of about 1500 and a hydroxyl value of 75.0 b) MN-3050one (trade name) manufactured by Mitsui Toatsu Chemical Co., Ltd. Triol with an average molecular weight of approximately 3000 and a hydroxyl value of 56.8, which is obtained by addition polymerizing propylene oxide to glycerin.

c) TD Any 8020 (trade name) manufactured by Mitsui Toatsu Chemical Co., Ltd., toluylene diisocyanate with 2,4 unit/2,6 unit = 80/20 (weight ratio).

d) LL-690-D (Product name) Manufactured by Sankyoki Co., Ltd.
Lead octenoate catalyst.

Reference example 1 TDI for 1000 parts of PPG-Dial-1500
-80/20255 parts at 80°C for 3 hours to obtain a 4.5% terminal incyanate group-containing prepolymer 10
0 parts, MW-3050one as polyol
111.4 parts and LL-690-D as catalyst 1.
0 parts were mixed until uniform at room temperature, degassed under reduced pressure, poured onto a Teflon plate, formed into a sheet, and left to harden. The physical properties of this sheet one week after molding were as shown in Table-1. After this sheet was attached to two iron boxes, when it was peeled off, it was torn and could not be reused.

Example 1 The mixture of prepolymer and polyol used in Reference Example 1 was coated uniformly on both sides of the woven fabric Kuraray Vinylon +2260 and measured in the same manner as in Reference Example 1. The physical properties are as shown in Table 1. , exfoliation and reclassification were possible.

Example 2 Non-woven fabric Toyobo Subabond LAE5088P-0 using fiber material
The process was carried out in the same manner as in Example 1 except that the sample was changed to 5.

The physical properties are as shown in Table 1, and peeling and readhesion were possible.

Example 3 The same process as in Example 1 was carried out except that the fiber material was changed to a glass cloth FibaTape (manufactured by BAY MILLS) which had been surface-treated with about 20 meshes. The physical properties are as shown in Table 1, and peeling and readhesion were possible.

Example 4 In Examples 1 to 6, when the mixture of prepolymer and polyol was applied thinly to only one side so that the unevenness of the fiber material appeared on the surface, the tackiness was as shown in Table 2. Adhesiveness decreased. After repeating adhesion and peeling five times, the adhesive strength did not change on both sides.

(Effects of the Invention) According to the present invention, a polyurethane pressure-sensitive adhesive tape can be peeled off from an adherend without damage.

Therefore, it can be reused and its adhesive strength does not decrease even after repeated use.

Table-1 Physical property test/results Table-2 Adhesion test results

Claims (1)

[Claims] (1) When producing polyurethane by reacting a polyol with an organic diisocyanate, a terminal isocyanate group obtained by reacting one or a mixture of two or more polyols having an average functional group number of 2 to 2.6 with an excess of an organic diisocyanate. A prepolymer having an average number of functional groups of 2 or more, and a mixture of one or more polyols whose sum with the average number of functional groups of the polyol mixture that is a component of the prepolymer exceeds 4 and does not exceed 5. A reusable polyurethane pressure-sensitive adhesive tape obtained by coating or impregnating a fiber material with a polyurethane obtained by reacting with an NCO/OH equivalent ratio of 0.65 to 1.15.