JP2002121528A - One-component urethane based adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a one-component urethane based adhesive which can obtain two conflicting effects of good coating working properties and sufficient initial adhesion strength by solving the problem of the conventionally used floor adhesive having both merits and demerits such that when the adhesive has a high strength, the initial adhesion strength is low and when the adhesive has a high initial adhesion strength, the working properties are inferior. SOLUTION: The one-component urethane based adhesive composition uses, as the prepolymer, a mixture of an isocyanate prepolymer A having a peak of the molecular weight in terms of styrene of <=10,000 and an isocyanate prepolymer B having a peak of the molecular weight in terms of styrene of 50,000-700,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-pack type (no mixing of a curing agent) urethane-based adhesive, and more particularly to an adhesive having excellent initial adhesive strength (initial tack) suitable for floor adhesives.

[0002]

2. Description of the Related Art Conventionally, floor adhesives include two-component urethane adhesives and two-component urethane adhesives in addition to one-component urethane adhesives.
Various adhesives such as a liquid epoxy adhesive, a one-component rubber adhesive, and a vinyl acetate adhesive have been used.

[0003]

Of these, two-part epoxy adhesives are very laborious because two parts must be mixed on site. Insufficient mixing causes poor curing. Furthermore, since it has a pot life (life), it is not suitable for construction of a large area, and the curing agent is toxic. Further, rubber-based and vinyl acetate-based ones do not have the pot life of a two-pack type, but have problems such as poor water resistance and poor adhesive strength.

[0004] On the other hand, urethane-based materials are excellent in flexibility and impact resistance, and are most suitable for bonding a plastic-based floor material or the like to plywood or concrete.
However, the two-pack type is not suitable for floors constructed in a large area because of the trouble of mixing on site and the pot life as described above. On the other hand, the one-liquid type is suitable for floors because it has no pot life, but the non-solvent type is poor in workability, and the solvent type is subject to dangerous substances regulation by an organic solvent.

As described above, all floor adhesives conventionally used have advantages and disadvantages. For example, those having high strength have low initial adhesive strength. Those having a large initial adhesive strength have poor workability and the like.

[0006]

The inventor of the present invention has proposed a property required for a floor adhesive in terms of working surface, namely, one-part property, easy to use, and even when the floor material has a curl. As a result of intensive research to obtain a one-pack type urethane-based adhesive having a performance that easily fits into the initial adhesive strength, an adhesive having sufficient initial adhesive strength and high adhesive strength was developed. The feature is that as a prepolymer,
The point is that a mixture of an isocyanate prepolymer A having a molecular weight peak of 10,000 or less in terms of styrene and an isocyanate prepolymer B having a molecular weight peak of 50,000 to 700,000 in terms of styrene is used.

The present invention is novel in that a mixture of a prepolymer having a very high molecular weight and a prepolymer having a low molecular weight is used, which has two contradictory effects of coating workability and initial adhesive strength. It was obtained.

The urethane prepolymer is an isocyanate compound obtained by adding an isocyanate group to a main chain component. Usually, it is obtained by reacting a polyol with a polyisocyanate.

Here, the polyol means polyethylene glycol, polypropylene glycol, neopentyl glycol, polyether glycol having active hydrogen, polyester glycol, polyether triol and the like, and other modified polyols. Specifically, as polyether glycol, polyoxyethylene diol,
Polyoxypropylene diol, polyoxybutylene diol, polytetramethylene diol, or the like can be used. Examples of the polyester glycol include poly (ethylene adipate) glycol, poly (propylene adipate) glycol, poly (ethylene butylene adipate) glycol, and poly (neopentyl sebacate) glycol. Other various triols and modified polyols include castor oil-modified polyol and epoxy-modified polyol. These molecular weights are 200 to 9000, preferably 500 to 500 in average molecular weight.
0.

As the main chain component, it is needless to say that other than the above-mentioned polyols, those having an isocyanate group at the end and having a structure which does not inhibit the urethane formation reaction can be used. For example, polyamine, polyamide and the like.

The polyisocyanate includes methylene diisocyanate, ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate,
2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate (LDI), 1,3,6-
Aliphatic isocyanates such as hexamethylene triisocyanate, hydrogenated-4,4'-diphenylmethane diisocyanate (hydrogenated MDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), 1,4-cyclohexane diisocyanate, hydrogenated-2, Alicyclic isocyanates such as 4-tolylene diisocyanate (hydrogenated TDI) and isophorone diisocyanate (IPDI); araliphatic isocyanates such as xylylene diisocyanate (XDI) and tetramethylxylylene diisocyanate (TMXDI); Diphenyl diisocyanate,
2,4- or 2,6-tolylene diisocyanate (TD
I), 2,4 or 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthalenediisocyanate (NDI), 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, O-tolidine diisocyanate, crude TDI , Polyphenylmethane polyisocyanate (crude MDI), triphenylmethane triisocyanate, and aromatic isocyanate such as tris (isocyanatephenyl) thiophosphate, but are not limited thereto.

In short, generally, two or more isocyanate groups are added to the terminal of a condensation polymer of an alcohol or an acid. The NCO group at the terminal reacts with moisture in the air, adsorbed water on the surface of the adherend, and the like to be cured.

The prepolymer A has a molecular weight peak of 10,000 or less in terms of styrene. The molecular weight was measured by GPC (gel permeation chromatography) using THF (tetrahydrofuran) as a mobile phase in comparison with polystyrene having a known molecular weight. Hereinafter, all molecular weights were measured by this method. Synthetic polymers are
Naturally, the degree of polymerization is a mixture of various polymers (prepolymers). Among these, the peak with the highest molecular weight is the peak, and this peak is 10,000 or less.
Therefore, it is a very small molecule as a prepolymer.

The small molecules (prepolymer A) have the effect of diluting the entire system such as prepolymer B and increasing the strength after the adhesive is cured. The peak of this small molecule (prepolymer A) is 10
If it is more than 000, the viscosity is large and the coating workability is reduced. In our experiments, 1500-3500 was preferred. Although various combinations of the above-mentioned polyols and polyisocyanates are possible, those based on MDI (methylene diisocyanate) are preferred.

Next, the prepolymer B is an isocyanate prepolymer having a molecular weight peak of 50,000 to 700,000 in terms of styrene. Those having such large molecules have a large initial adhesive strength. In our experiments, 5
At 0000 or less, there was almost no effect, and at 700,000 or more, the viscosity was too large, making it difficult to use even a diluent. The prepolymer was preferably a TDI prepolymer.

The mixing ratio of the prepolymer A and the prepolymer B is not particularly limited. It may be determined depending on various properties such as the adhesive strength and initial adhesive strength depending on the prepolymer used. However, the mixing ratio of prepolymer A and prepolymer B was preferably from 1: 2 to 10: 1 by weight. This is because the molecular weight peak of prepolymer A was 2
At 500, the peak value of the prepolymer B is about 300,000.

The above urethane prepolymers A and B
Are not limited to one type, and one or both types may be plural types.

If the viscosity is too high, application becomes difficult, so a diluent may be added. In the present invention, DOA (dioctyl adipate), hydrocarbons such as naphthas and kerosene (flash point of 40 ° C. or higher), and those having a high flash point (at least 40 ° C. or higher) such as propylene carbonate are preferable. Even if the flash point is simply high, methylene chloride which is problematic for the environment is not preferred. The viscosity is adjusted by adding the above diluents. Those having a low flash point, such as conventional toluene and xylene, are not preferred for safety. In addition, toluene and the like naturally have high volatility, which is not preferable from an environmental point of view. In the present invention, when a solvent is used, one of the features is that a solvent having a high flash point is used.

Further, an aliphatic or alicyclic isocyanate and / or a urethane prepolymer C thereof is replaced with a prepolymer A
1 to 5 with respect to 100 parts by weight of the mixture of
0 parts by weight may be added. This adds to the pot life. That is, the time until the cured film is formed on the surface becomes longer. Alternatively, other pot life extending agents may be used separately or in combination therewith.

The adhesive of the present invention thus obtained can contain a filler, a diluent (a plasticizer, a solvent, etc.), a curing catalyst and other additives within a range not to impair the purpose of the present invention. Good.

Examples of the filler include calcium carbonate, carbon black, clay, talc, mica, titanium oxide, zeolite, diatomaceous earth, silica and the like, and these can be used alone or in combination. Among the diluents, as a plasticizer, dioctyl adipate (DOA), dioctyl phthalate (DOP), dibutyl phthalate (DBP),
Examples thereof include dilauryl phthalate (DLP) and trioctyl phosphate (TOP). Examples of the solvent include hydrocarbons such as naphtha and kerosene, propylene carbonate and ethylene carbonate, and the like. Methyl ethyl ketone, toluene, ethyl acetate, acetone, cellosolve and the like are preferable. Acetate, hexane or the like may be used. Both can be used alone or as a mixture.

Further, as a curing catalyst, dibutyltin dilaurate, cobalt naphthenate,
As amines, triethylamine, triethylenediamine, morpholino ethers, imidazoles and the like can be used as amines, and stannous chloride and tetra-n-butyltin can be used, but dibutyltin dilaurate is preferred.
Other additives include a silane coupling agent, a titanate coupling agent, an ultraviolet absorber, an antioxidant, a drying agent, a tackifier, and the like, and can be used alone or in combination.

The adhesive to which the adhesive of the present invention is adhered is a long PVC sheet, artificial turf, rubber tile, linoleum sheet, composition tile, homogeneous style, cork tile, wood flooring and the like.

[0024]

The present invention will be described in more detail with reference to the following examples. Components of Examples 1 to 11 and Comparative Examples 1 to 6 are as shown in Tables 1 and 2. Examples 1 to 11 are actually 1 to 11;
Comparative Examples 1 to 6 have ratios 1 to 6. In the table, A is a prepolymer A, and A1, A2, and A3 are examples therein. B, C
The same is true for Diluent 1 is dioctyl adipate, 2 is a hydrocarbon mixture having a flash point of 40 ° C. or higher, and 3 is toluene. The viscosity of the mixture (adhesive) is 15000 mP
The addition amount was adjusted so as to be a · s (25 ° C.). Fillers (Whiteton SB Red / Shiraishi Calcium Co., Ltd.) and thixotropic agents (Aerosil # 20) were used in all Examples and Comparative Examples.
0, manufactured by Nippon Aerosil Co., Ltd.), a dehydrating agent (Additive TI, manufactured by Sumitomo Bayer Urethane Co., Ltd.), and a catalyst (dibutyltin dilaurate).

[0025]

[Table 1]

[Table 2]

First, a production example of the prepolymer used in the present invention will be described. Prepolymer A1 polyol: polypropylene glycol (molecular weight of about 20
00) Isocyanate group-imparting substance: 4,4′-MDI 100 parts by weight of this polyol and 25 parts by weight of isocyanate are reacted at 80 ° C. for 5 hours to give a molecular weight peak of about 25.
00 material was obtained. Naturally, unreacted isocyanate remains.

Prepolymer A2 polyol: polypropylene glycol (molecular weight of about 20
00) Isocyanate group-imparting substance: 4,4′-MDI 100 parts by weight of this polyol and 37.5 isocyanate
The parts by weight were reacted at 80 ° C. for 5 hours to obtain a substance having a molecular weight peak of about 2500. Naturally, unreacted isocyanate remains.

Prepolymer A3 Polyol: Polypropylene glycol (molecular weight: about 2,000) Ethylene butylene adipate glycol Isocyanate group-providing substance: 4,4′-MDI 100 parts by weight of this polyol mixture and isocyanate 2
After reacting 5 parts by weight at 80 ° C. for 5 hours, a substance having a molecular weight peak of about 2500 was obtained. Naturally, unreacted isocyanate remains.

Prepolymer A4 Polyol: Polypropylene glycol (molecular weight: about 2,000) Isocyanate group-imparting substance: 2,4′-MDI 4,4′-MDI 100 parts by weight of this polyol mixture and 25 parts by weight of isocyanate mixture are mixed at 80 ° C. for 5 hours. The reaction yielded a material with a molecular weight peak of about 2500. Naturally, unreacted isocyanate remains.

Prepolymer A5 polyol: polypropylene glycol (molecular weight of about 20
00) Isocyanate group-imparting substance: 2,4-TDI 100 parts by weight of this polyol mixture and 17.4 parts by weight of the isocyanate mixture were reacted at 80 ° C. for 5 hours to obtain a substance having a molecular weight peak of about 2400. Naturally, unreacted isocyanate remains.

Prepolymer B Polyol: polypropylene glycol (molecular weight: about 2,000) Neopentyl glycol (NPG) Isocyanate group-providing substance: 2,4-TDI 100 parts by weight of this polypropylene glycol, NPG1
5.6 parts by weight and 38.3 parts by weight of isocyanate were reacted at 100 ° C. per one shot to obtain four kinds of prepolymers having different molecular weight peaks as follows.

Prepolymer B1: a molecular weight peak of about 30
000 prepolymer B2: molecular weight peak about 50,000 prepolymer B3: molecular weight peak about 700,000 prepolymer B4: molecular weight peak about 900,000

Prepolymer B5 Polyol: Polypropylene glycol (molecular weight: about 2,000) Ethylene butylene adipate glycol (molecular weight: about 2,000) Neopentyl glycol (NPG) Isocyanate group-providing substance: 2,4-TDI 50 parts by weight of this polypropylene glycol, ethylene butylene adipate 50 parts by weight of glycol, NPG15.
6 parts by weight and 38.3 parts by weight of isocyanate are reacted at 100 ° C. for one shot to give a molecular weight peak of about 700,000.
Was obtained.

Component C C1 is xylylene diisocyanate (XDI), C2 is isophorone diisocyanate (IPDI), and C3
Is the following prepolymer.

C3 polyol: polypropylene glycol (molecular weight of about 20
00) Isocyanate group-providing substance: xylylene diisocyanate (XDI) 100 parts by weight of this polypropylene glycol is reacted with 28.2 parts by weight of isocyanate to give a molecular weight peak of about 2
400 prepolymers were obtained.

Using the above prepolymers, Examples 1 to
11 and Comparative Examples 1 to 6 were prepared. The results are shown in Tables 1 and 2. In the above embodiment, the adhesive strength (initial) was determined by applying the prepared adhesive to a flexlate plate at 350 g / m ² using a comb iron, applying a long PVC sheet every 10 minutes, and rolling with a hand roller. After pressing, the maximum value of the value obtained by measuring the 90 ° C. peel adhesion strength was shown. The unit is N /
25 mm. The pot life is indicated by the time (unit: minutes) when a long PVC sheet is stuck every 10 minutes on the adhesive applied in the same condition as in the initial adhesion test, and the transfer rate of the comb mountain becomes 50%. Was. The Fire Service Act has indicated whether there is any application. Further,-cannot be diluted and cannot be evaluated.

As can be seen from Table 1, when prepolymer A and prepolymer B are mixed, the initial adhesive strength is all 0.9 N / 25 mm or more, which is sufficient. If the initial adhesive strength is small (0.6 N / 25 mm or less), the sheet of the floor material to be bonded will be separated from the bonding surface due to curl or warpage of the sheet, and will be cured in that state. Of course, sticking to a wall or the like is very difficult. The pot life is 40 ~
It turns out that 90 minutes is enough. If this time is short, the workability is poor because the tackiness (adhesiveness) is quickly lost, so that a large area cannot be stuck at once.

In the comparative examples shown in Table 2, Comparative Examples 1 and 2 are small prepolymers only having small molecules and thus have low adhesive strength, and Comparative Example 3 is only prepolymers having large molecules.
Even if a diluent is added, it cannot be diluted enough to be applied. In Comparative Example 4, since the molecular weight of the prepolymer B was small, the adhesive strength was also small. In Comparative Example 5, since a prepolymer having a very high molecular weight was mixed, the dilution could not be performed to the extent that it could be applied even if a diluent was added as in Comparative Example 3. Comparative Example 5
Since toluene is used as the solvent, it is a hazardous substance specified by the Fire Service Law as a whole.

[0039]

The adhesive of the present invention is a one-component urethane-based adhesive having excellent workability and a long sticking time and excellent initial adhesive strength. Furthermore, the use of a diluent or the use of a specific solvent does not correspond to dangerous goods specified by the Fire Service Law. Further, the effect of the present invention is not limited to floors, but is also effective for a wide range of adhesives such as walls and ceilings.

Claims (5)

[Claims] 1. A prepolymer having an isocyanate prepolymer A having a molecular weight peak of 10,000 or less in terms of styrene, and a prepolymer having a molecular weight peak of 5000 in terms of styrene.
A one-pack type urethane-based adhesive composition, comprising a mixture of 0 to 700,000 isocyanate prepolymer B. 2. The one-component urethane adhesive composition according to claim 1, wherein the mixing ratio of the prepolymer A and the prepolymer B is 1: 2 to 10: 1 by weight. 3. The one-part urethane adhesive composition according to claim 1, wherein a diluent is mixed. 4. The one-part urethane adhesive composition according to claim 3, wherein the diluent has a flash point of 40 ° C. or higher. 5. The method according to claim 1, wherein the aliphatic or alicyclic isocyanate and / or the urethane prepolymer C thereof is added in an amount of 1 to 100 parts by weight of the mixture of the prepolymer A and the prepolymer B.
5. The method according to claim 1, wherein 50 parts by weight are added.
Liquid type urethane adhesive composition.