JPS61115977A - Reactive hot-melt adhesive - Google Patents

Abstract

PURPOSE:To provide a reactive hot-melt adhesive consisting of a urethane prepolymer with isocyanate groups in both terminals, a specified resin and an aromatic oil and exhibiting excellent low temp. coating workability, instantaneous and heat-resistant adhesion, viscosity stability and storage stability. CONSTITUTION:The adhesive is prepared by blending (A) 30-69.8wt% urethane prepolymer containing isocyanate groups on both terminals and having a viscosity of 100,000cP or higher at 25 deg.C and an NCO equivalent of below 5wt% (B) 30-50wt% tackifier resin which is compatible with (A) and reactive with the isocyanate group of (A) and has an m.p. of 60-140 deg.C, selected from among coumarone-indene resin, terpene/phenol resin having a terpene/phenol ratio of 1.0-3.0, rosin derivative obtained by removing active hydrogen or a part or whole of double bonds in abietic acid-based rosin by esterification, etc., and styrene resin and (C) 0.2-2.5wt% aromatic oil (e.g. 1-xylyl-1,3- diphenylbutane).

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a reactive real-melt adhesive having both hot-melt and reactive adhesive properties.

(b) Conventional technology Traditionally, adhesives can be roughly divided into hot melt type and anti-15 type adhesive.
(hardening) type is known, and hot melt adhesive is
Adhesion work is efficient because adhesive strength can be obtained instantaneously by cooling and solidifying after heating and melting, but it has the disadvantage that adhesive strength is low when exposed to high temperatures.

This is busy, anti-151! ! Adhesives are advantageous in that they can provide heat-resistant adhesive strength, but they have the disadvantage that their initial adhesive strength is low and, unlike hot-melt adhesives, adhesive strength cannot be obtained instantaneously.

Therefore, in recent years, various reactive hot melt adhesives that have both the instant adhesive properties of the hot melt type and the heat-resistant adhesive strength of the anti-I5 type have been studied (Japanese Patent Publication No. 51-30898, etc.).
.

Some hot melt adhesives are required to have properties that allow them to be melted and coated at low temperatures in terms of energy saving and work environment, but the above-mentioned conventional reactive hot melt adhesives are sufficient for such low temperature coating workability. It was indescribable.

ρ→ Problems to be Solved by the Invention The present invention solves the problem at low temperatures (less than 100°C, for example about 90°C) K
The object of the present invention is to provide a reactive hot-melt adhesive that has excellent coating workability, instant adhesive properties, and excellent heat-resistant adhesive properties.

In the summer, the present invention has excellent viscosity stability when exposed to the air, such as when applied using a single roll coater, and also has excellent storage stability when stored in a substantially closed container. The purpose of the present invention is to provide a reactive hot melt adhesive.

) Means for solving the problem The urethane prepolymers used in the present invention include, for example, 2,4-tolylene diisocyanate, 2,6
- A diisocyanate compound consisting of a single substance or a mixture thereof such as tolylene diisocyanate, hequinamethylene diisocyanate, and 5-naphthylene diisocyanate, and ethylene glycol, propylene glycol,
1,4-butadiol, 1,4-butynediol monomer polymer and polytetramethylene ether,
Examples include prepolymers obtained by addition polymerization with diol compounds consisting of a single glycol or a mixture thereof.

The viscosity of the prepolymer is preferably 100,000 cps or more at 25°C. This is because if a prepolymer with a strength of less than 100,000 cps is used, the initial cohesive force of the resulting adhesive tends to be weak.

Further, it is preferable that the NCO equivalent of the prepolymer is less than Fis weight %. This is because if more than 5% by weight of the prepolymer is used, the adhesive tends to become brittle.

The reason why incyanate groups are required at both ends of the molecule is mainly that after the adhesive melts and solidifies, the moisture in the atmosphere reacts with the incyanate groups in the adhesive, forming long chains and increasing the molecular weight, which leads to adhesion. It is possible to strengthen the cohesive force of the agent. Hy is a urethane prepolymer with an isocyanate group at one end of the molecule.
csK, the cohesive force of the adhesive will not be strong enough, making it unsuitable.

If the amount of urethane prepolymer is too small, the reaction with moisture in the air will be insufficient, and sufficient heat resistance strength will not be developed.
The adhesive becomes hard and brittle after bonding between base materials. On the other hand, if the amount is too large, the initial cohesive force will be weak and the adhesive force immediately after bonding will be weak. Therefore, it is necessary that the adhesive contains 3 to 75% by weight, preferably 45 to 70% by weight.

The tackifying resin used in the present invention is required to have compatibility with the urethane prepolymer, and JJ: softening at 60 to 140°C with little or no reactivity with the incyanate groups in the urethane prepolymer. Preferably, it has a temperature. In the present invention, the following were selected to have the effect of improving the instantaneous adhesion of the Fi adhesive.

Both coumaron resin and coumaron-indene resin (a) are made from solvent naphtha that is mixed in light oil in coke oven gas (tar), and the former is a polymer of coumaron, coumaron homologs, or coumaron derivatives. , the latter being primarily a copolymer of coumaron and indane.

Terpene-7 enol Il fat (b),! =d Refers to a thermoplastic resin obtained by copolymerizing terpenes and phenols, and preferably has a terpene/phenol molar ratio of 10 to 10. Preferable examples of terpenes include carbon &10 monoterpenes, such as α-pinene, β-pinene, can-7-eine, hydrogenated products thereof, and carbon &20 diterpenes.

Examples of rosin derivatives (C) obtained by eliminating the active hydrogen of avicenoic acid type rosin by esterification etc. or eliminating some or all of the double bonds include hydrogenated rosin, hydrogenated rosin glycerin ester, and water. Examples include added rosin pentaefthritol, disproportionated rosin, polymerized rosin, etc., and hydrogenated rosin, hydrogenated rosin glycerin ester, etc. are preferably used.

The styrene resin (d) is a hydrocarbon resin such as a low molecular weight styrene resin obtained by polymerizing styrene, α-methylstyrene, cumene, etc., and also includes hydrogenated resins thereof. The styrene-based tackifying resin is commercially available (for example, Picotex, etc.) and can be obtained.

If the content of these tackifying resins is too low, it will not be possible to impart strong adhesive cohesive force to the urethane prepolymer.
30-5, as the instantaneous adhesion will be weak, and if there is too much adhesive, the adhesive will become brittle and strong adhesive strength will not be obtained.
0 is taken as amount %.

The aromatic oil used in the present invention refers to aromatic components of oils that are widely known as process oils, extender oils, softeners, etc. as rubber softeners. 2-6 hydrocarbon residues! /c
Those in which 2 to 3 benzene rings or alkylbenzene rings are bonded are preferable, and specific examples include Fil-xylyl 1-monomer, 3-diphenylbutane, bis(agricultural methylperzeline) xylene, l-xyclyl 1-(3-α methylbenzene) phenyl)ethane 412>f list ff larel.

If the content of aromatic oil is too small, the low viscosity, that is, the low-temperature coating workability, which is a major feature of the present invention, will be impaired, while if it is too large, the cohesive force will decrease and the initial adhesive force will become weak. ~25% by weight, preferably 1-16~20% by weight.

It is difficult to use non-aromatic oils, such as 7-tene-based oils and Nomurafuin-based oils, because they have poor compatibility with the Kurekun prebolimer used in Zero-Hatsu IJ'iK, but it is difficult to use them alone. ``Can be used in combination with oil.

The adhesive Kt-t of the present invention, the above-mentioned urethane prepolymer,
In addition to tackifier resins and aromatic oils, paste resins in general hot melt adhesives such as polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethylene acrylate copolymer, and actiic polypropylene; terpene resins, and oils Cyclic/J7 olefins and their hydrogenated products and other adhesion-imparting resins; waxes such as low molecular weight polyethylene, microcrystalline waxes, and polymerized waxes (nidioctyl 7-thale, digtyl 7-thale), TPP
Plasticizers such as the following may be contained within the range that can achieve the objects of the present invention.

The adhesive Fi of the present invention can be applied at a low temperature of 70 DEG C. to less than 100 DEG C., but in some cases, it may be heated to about 110 DEG C. before application.

λ・ Various rat melt coaters and hot melt applicators can be used as coating equipment, especially roll coaters.
is preferably used.

) Effects of the invention The reactive hot melt adhesive of the present invention can be used at relatively low temperatures (100
It has a low viscosity even at temperatures below 90° C. (for example, about 90° C.), so it has excellent low-humidity application workability, and has instant adhesive properties and heat-resistant adhesive properties that are equal to or better than conventional reactive hot melt adhesives.

Furthermore, the present invention has excellent viscosity stability when Kn is released in the air, such as when coating with a single roll coater, and also has excellent storage stability when stored in a substantially sealed container. It has various advantages in that it takes a short time to develop practical strength.

(e) Examples Examples of the present invention are shown below. Parts simply refer to parts by weight.

The following measurement method was used for each property.

1) The adhesive obtained by kneading to uniform melt viscosity is heated to 90°C, and B
It was measured using an M-type viscometer with a 40-meter diameter.

2) A polypropylene plate bonded with a temperature-rising softening point adhesive was measured at JIS-6844111m* using an automatic external hot air circulation incubator.

3. Storage Stability Sample 2009 was sealed in a synthetic resin bag with aluminum laminated on its surface, left open at 90°C, and storage stability was checked by the rate of increase in viscosity. That is, a case where the viscosity was within twice the initial value was considered to be a pass, and the period was expressed.

4) Viscosity stability Changes in viscosity after 4 and 8 hours were checked according to melt viscosity measurement.

5) Reaction rate The polypropylene plates bonded together using the method described in 8) with an adhesive were cured under conditions of 20° C. and 60% circularity, and the time required to obtain practical strength was measured.

6) Initial Cohesive Strength (Shear Adhesive Strength) Polypropylene plates immediately after being bonded using adhesive using method 8) were heated at 1o in a thermostatic chamber at 20℃ x 6G% temperature.
A load of OP was applied, and the time until the adhesive surface peeled off and fell was measured and expressed in minutes.

7) Adhesive strength Glue each material by the method of 8) for 20'
After leaving it in a thermostatic chamber at 60% CX1i degree for 12 hours, it was kept at the desired measurement temperature for 7j 3 hours, and the shear detachment strength was measured using a UTM-III type Tensilon at a tensile speed of 25 m/min. .

8) Urethane prepolymer having isocyanate groups at both ends (NCO group content: 2
96) and the tackifying resin were heated to a temperature equal to or higher than the softening temperature of the tackifying resin and kneaded.

The presence or absence of compatibility was determined by visually confirming whether or not the two drank the Jun-hi mixture. The polyurethane prepolymer and tackifying resin used in each example were both compatible.

9) Adhesive application method 90@cKIR The adhesive was applied to each material using a roll coater with a coating thickness of 30 to 150 microns, and the adhesive was pressed with an open time of 30 seconds.

50 parts of cretan prebolimer (NCO group content 1% by weight) having isocyanate groups at both ends obtained by addition polymerization of polypropylene glycol and polypropylene glycol, 10 parts of aromatic oil, and terpene mainly composed of α-pinene. Terpene phenol resin obtained by copolymerizing and phenol 4
0 parts were heated and kneaded at 120°C to obtain an adhesive.

The aromatic oil used was one whose main components were l-xylyl 1°3 diphenylbutane, bis(αmethylbenzene)xylene, and 1xylyl 1-(3-αmethylbenzene phenyl)ethane.

The properties and performance of this adhesive were as shown in Table 1.

(Margins below) Table 1 (Note) Shows the case where a PP/A/Fi polypropylene plate and an aluminum plate are bonded (the same applies below).

Comparative Example 1 30 parts of terpene phenol resin and ethylene-vinyl acetate copolymer (vinyl acetate content: 28%) were added to 50 parts of cretan prebolymer having incyanate groups at both ends (NCO group content: 15% by weight). , softening point 130℃, M
20 parts of I400) were blended and mixed uniformly at 140°C to obtain an adhesive.

The properties and physical properties of this adhesive were as shown in Table 2.

However, since coating is difficult unless the temperature is 120°C or higher, the viscosity stability Fi was measured at 120°C.

(Left below) Table 2 Examples 2 to 10 Adhesives were obtained from the compositions shown in Table 3 in the same manner as in Example 1. However, cretan prevolimer (NGO content 1
5% by weight) as Takenate A-260 (manufactured by Kurade Pharmaceutical Co., Ltd.)
, Mighty Ace G125 (manufactured by Yasuhara Resin Co., Ltd.) as a terpene-phenol copolymer, Ester Gum H (manufactured by Arayo Chemical Co., Ltd.) as a hydrogenated rosin glycerin ester, and Picotex 1oo (manufactured by Marchiery Co., Ltd.) as a styrene resin. The same oil as in Example 1 was used.

A4- The properties and performance of these adhesives are shown in Table 4.

Comparative Examples 2 to 10 Adhesives were prepared in the same manner as in Example 1 from the compounded compositions shown in Table 5 (the same urethane prepolymer, tackifier resin, and aromatic oil were used as in Examples 2 to 10). I got it.

The properties and performance of each adhesive were as shown in No. 6*.

Table 5: * in Table 6 indicates that the adhesive layer was brittle and peeled off easily.

Further, in Comparative Example 4, DOP was used as a substitute for the aromatic oil used in the present invention, but the compatibility between DOP and the urethane prepolymer was poor, and as a result, the melt viscosity was extremely high, making it difficult to apply to the sample. Met.

Claims (1)

[Claims] 1 30 to 75% by weight of a urethane prepolymer having isocyanate groups at both ends, coumaron resin or coumaron-indene resin (a), terpene-phenol resin (b), and abietic acid type rosin that are compatible with the urethane prepolymer. At least one tackifying resin selected from rosin derivatives (c) and styrene resins (d) obtained by eliminating active hydrogen by esterification or the like or partially or completely eliminating double bonds 30-50 % by weight, and 0.2 to 25% by weight of aromatic oil.