JPH0252948B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a moisture-curing adhesive composition that cures using moisture in the laminating material or in the air, and more particularly, a moisture-curing adhesive composition that is made of a urethane prepolymer containing a specific active isocyanate group, an organoalkoxysilane compound, and a filler. The present invention relates to a one-component urethane adhesive composition that has excellent adhesion to metals, painted metals, tiles, etc., and has a fast curing speed to reach practical adhesive strength even under low humidity conditions. Generally, various composite panels with excellent heat insulation, cosmetic properties, and durability are used as building materials and transportation container materials. For example, construction materials include treated steel sheets, tiles, aluminum, untreated stainless steel, surface-treated stainless steel such as paint, plastic boards, etc., plywood, flexible boards,
Composite panels bonded together with gypsum board, paper honeycomb, etc. can be used as exterior wall panels for structures.
Interior wall panels, partition panels, etc., blackboards for teaching materials,
Used for container box frames, etc. Conventionally, two-component epoxy resin adhesives have been used for bonding these composite panels. However, with this epoxy resin adhesive, the main resin and curing agent need to be stored separately and mixed before use, making the work cumbersome.In addition, the curing reaction is slow at working environment temperatures below 10°C, and this Under these conditions, curing is poor and the adhesive properties inherent to epoxy resins cannot be obtained. Furthermore, since an organic amine compound is used as the curing agent or catalyst, the irritating nature of the method induces skin inflammation and rash, which poses health and safety problems. The inventors of the present invention have made various efforts to obtain a new adhesive that does not have these drawbacks, and as a result, we have developed a method that cures at low temperatures by blending a specific active isocyanate group-containing urethane prepolymer, an organoalkoxysilane compound, and a filler. The inventors have discovered that a moisture-curable one-component adhesive with excellent properties and almost no skin irritation can be obtained, and have completed the present invention. That is, the present invention provides polyoxyethylene containing a polyester polyol and 20 to 70 mol% of ethylene oxide. It consists of an active isocyanate group-containing urethane prepolymer obtained by reacting a mixture of propylene polyols with an excess of an organic polyisocyanate compound, an organoalkoxysilane compound, and a filler. A one-component moisture-curable adhesive composition, characterized in that the mixing ratio is 8:2 to 2:8 (weight ratio), and the amount of the filler is 20 to 70% by weight. It provides: The polyester polyol used in the present invention is a hydroxy group-terminated polyester polyol manufactured from a polybasic acid and a hydroxy compound. Examples of the polybasic acid component include phthalic acid, adipic acid, terephthalic acid, isophthalic acid, sebatenic acid, dimerized linoleic acid, maleic acid, and dialkyl esters thereof. Examples of the hydroxy compound include diols such as ethylene glycol, propylene glycol, butylene glycol, and diethylene glycol, and triols such as hexanetriol, trimethylolpropane, and glycerin. A polyester polyol can be obtained by reacting one or more of these polybasic acids and hydroxy compounds by a conventional method. This polyester polyol preferably has a molecular weight of 500 to 5,000 and has 2 to 3 hydroxy groups in one molecule. A particularly preferred polyester polyol has a molecular weight obtained by the reaction of adipic acid and propylene glycol.
It is a bifunctional linear polyester diol having a molecular weight of 1,000 to 3,000, and is a commercially available New Ace F7-67.
Includes F7-68, F1-1212-29 (manufactured by Asahi Denka Kogyo Co., Ltd.), etc. Polyoxyethylene-propylene polyol is a random or block copolymer obtained by ring-opening polymerization of ethylene oxide and propylene oxide in the presence of one or more low-molecular active hydrogen compounds having two or more active hydrogen atoms. and has 2 to 3 hydroxy groups in one molecule. Examples of the low-molecular active hydrogen compounds used include diols such as ethylene glycol, propylene glycol, butylene glycol, and 1,6-hexanediol, and triols such as glycerin, trimethylolpropane, and 1,2,6-hexanetriol. . A particularly preferable polyoxyethylene-propylene polyol has a molecular weight of 20 to 70 mol% of copolymerization of ethylene oxide.
1,000 to 5,000, and has two hydroxy groups in one molecule. It has good compatibility with polyester polyols. If the copolymerization ratio of the ethylene oxide is less than 20 mol%, the compatibility with the polyester polyol will be poor;
If it exceeds 70 mol%, it becomes hydrophilic and is undesirable in terms of durability in the final product adhesive. The above polyester polyol and polyoxyethylene-propylene polyol are 2:8 to 8:2.
It is desirable to mix and use in the ratio of (weight ratio),
If the amount of polyester polyol exceeds the above range, the adhesion to metals, plastics, wood, etc. will improve, but since the polarity is strong and hydrogen bonding is high, the viscosity of the urethane prepolymer obtained by reacting with organic isocyanate compounds will be high. In addition to being difficult to apply, it also requires the addition of a large amount of organic solvent, which poses health and safety issues, as well as the risk of fire. On the other hand, polyoxyethylene
When the proportion of propylene polyol used exceeds the above range, the compatibility with the polyester polyol deteriorates, making it impossible to obtain a uniform mixed system, which is undesirable. From the viewpoint of compatibility, the above mixture usually has a viscosity of
It is in the range of about 8000 to 20000. The organic polyisocyanate compound to be reacted with the above polyol mixture in the present invention includes:
2,4/2,6-tolylene diisocyanate,
4,4'-diphenylmethane diisocyanate,
Polyphenylmethane polyisocyanate derived from 4,4'-diphenylmethane diisocyanate (commonly known as crude MDI), xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, triphenylmethane triisocyanate, etc. aliphatic, cycloaliphatic or aromatic di- or triisocyanate compounds. Among these compounds, 4,4'-diphenylmethane diisocyanate and crude MDI are particularly preferred because they have a relatively low vapor pressure, react quickly with moisture even at low temperatures, and are less toxic to humans. An active isocyanate group-containing polyurethane prepolymer is obtained by reacting these organic polyisocyanate compounds with a mixture of polyester polyol and polyoxyethylene-propylene polyol in a conventional manner. This reaction is carried out using an excess of the organic polyisocyanate compound and is usually
Ratio of hydroxy groups in polyol to isocyanate groups in polyisocyanate compound (NCO/
OH) is 4.0 to 10.0, preferably 6.0 to 8.0 (equivalent ratio)
React within the range. For example, polyol is preheated to a temperature of 70 to 100°C, an excess of an organic polyisocyanate compound in the above range is added while stirring under a nitrogen gas atmosphere, and if necessary, a catalyst such as dibutyltin dilaurate or lead naphthenate is added. By adding and reacting for 2 to 4 hours, the active isocyanate group is 6.0 to 14.0% by weight.
A urethane prepolymer containing urethane prepolymer is obtained. If the content of isocyanate groups (NCO) is reduced,
The storage stability of the intended adhesive composition deteriorates, resulting in an increase in viscosity or a decrease in adhesive properties during storage. If the Masa NCO content becomes too large, for example exceeding 14.0%, the reaction between the active NCO groups in the adhesive composition and the moisture in the laminating material or in the air will proceed rapidly, resulting in the generation of carbon dioxide gas. Therefore, the adhesive may foam, resulting in a reduction in adhesive strength. The organoalkoxysilane compound, which is another component distributed in the adhesive composition of the present invention, has the general formula R-Si≡(X) ₃ or R-Si≡(R′)(X) ₂ [wherein R is an organic group having a vinyl group, an epoxy group or a mercapto group, R' is a lower alkyl group having 1 to 3 carbon atoms, and X is a methoxy or ethoxy group. As a specific example,
Vinyl alkoxysilanes such as vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinyldimethylmethoxysilane; γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, 3,4-epoxy Examples include epoxyalkoxysilanes such as cyclohexylethyltrimethoxysilane and 3,4-epoxycyclohexylethylmethyldimethoxysilane; and mercaptoalkoxysilanes such as γ-mercaptopropyltrimethoxysilane. These organoalkoxysilanes can be used alone or in combination of two or more, and the blending ratio is 0.05 to 2.0% by weight, particularly 0.05 to 2.0% by weight based on the total weight of the adhesive composition.
A range of 1.0% by weight is preferred. The blending ratio is 0.05
If it is less than 1.0%, the adhesiveness to the laminating material may be insufficient, and if it exceeds 1.0%, the adhesiveness is excellent, but the cost is high and it is not economical. The adhesive composition of the present invention further includes various inert fillers, plasticizers, solvents, dyes, pigments, catalysts, etc., which do not have reactive groups with the active isocyanate of the above components.
Anti-aging agents, water-absorbing agents, etc. can be added. In order to obtain a particularly stable adhesive composition, it is preferable to incorporate a filler, and usually a filler is added to the total weight of the composition.
It is used in a range of 20 to 70% by weight. Such a filler is preferably one that does not contain much water of crystallization and is free of water. Preferred fillers include, for example, calcium carbonate, talc, clay, carbon, silicic anhydride, and metal powder. As the calcium carbonate, ground calcium carbonate is preferable to precipitated calcium carbonate, and in particular, relatively coarse particles that do not pass through a sieve of 200 mesh or less are preferable because moisture can be easily removed by drying. Further, talc is a scale-like particle, and when used in combination with other fillers, it functions as an anti-settling agent, so it is desirable to use them together. In this case, 10 parts by weight or more of talc is used per 100 parts by weight of calcium carbonate or clay. It is desirable that these fillers have as little water content as possible.
It is usually blended after being dried to a moisture content of 0.05% by weight or less in a heating drying oven at 100°C or higher. moisture content
If more than 0.05% of filler is used, it will react with the active isocyanate groups in the adhesive composition and cause an increase in viscosity, resulting in poor storage stability of the composition. By adding a filler, the adhesion force of the adhesive to the laminating material and the cohesive force of the adhesive are balanced, showing favorable adhesion (if you observe the state of failure of the adhesive in an adhesive force test, you will notice that it has become a cohesive failure. ). Other plasticizers that can be used in the formulation include phthalate esters such as dibutyl phthalate, di(2-ethylhexyl) phthalate, butylbenzyl phthalate, dinonyl phthalate, dioctyl adipate, didecyl adipate, dioctyl sebacate, etc. Aliphatic dibasic acid esters, phosphate esters such as tributyl phosphate and tricresyl phosphate, alkyl-substituted terphenyl, partially hydrogenated alkyl terphenyl,
Examples include inert plasticizers that are non-reactive with isocyanate groups selected from hydrocarbons such as aromatic process oils, chlorinated paraffins, and the like. This plasticizer is usually 5 to 50% by weight based on the weight of the adhesive composition.
It is blended at a ratio of 25% by weight and is effective in reducing viscosity and improving coating workability. Note that adding an excessive amount of plasticizer is not preferable because it inhibits adhesion to the laminating material. Any solvent that is compatible with the urethane prepolymer can be used, and is blended in accordance with the coating workability of the adhesive composition. From the viewpoint of adhesive application workability and drying conditions, it is preferable to use adhesives with a boiling point of 140°C or higher and a boiling point of 220°C or lower so that they do not remain in the cured product.In particular, use an appropriate combination of solvents obtained from petroleum fractions. It is desirable to have a mixture within the above boiling point range. Examples of the catalyst as a curing accelerator include dibutyltin dilaurate, lead octylate, and bismuth octylate, which may be blended in an amount of 0 to 1.0% by weight. In addition, anti-aging agents are not particularly essential, but examples include 2,6-di(t-butyl)-4-methylphenol (BHT), 2,2-methylene-bis(4-
Known stabilizers such as methyl-6-t-butylphenol) and nickel dibutyldithiocarbamate (NBC) are used, and are usually blended in an amount in the range of 0.1 to 2.0% by weight. The water-absorbing agent is added to remove moisture from the adhesive composition, and examples thereof include calcium oxide and molecular sieves. Further, such water absorbing and hygroscopic agents can also be used for dehydrating polyols, plasticizers, solvents, etc. used in the present invention. The urethane-based one-component moisture-curable adhesive composition of the present invention is prepared by first reacting a mixture of polyester and polyoxyethylene-propylene polyol, which has been dehydrated with a dehydrating agent, with an excess of an organic isocyanate compound. Isocyanate group-containing urethane prepolymer (NCO6~14.0%)
Then fillers, dyes and pigments, plasticizers, solvents, and other additives are added, and finally catalysts, silane compounds, etc. are added. Since the moisture-curable adhesive composition of the present invention is a one-component type, unlike conventional epoxy resin adhesives, there is no need for the process of mixing a base ingredient and a curing agent, which saves work time and streamlines work. . Furthermore, unlike conventional two-component adhesives, there is no need to worry about pot life due to curing reactions after mixing. Furthermore, the composition of the present invention does not cause any inflammation even when it comes into contact with the human body, so no special equipment is required for handling it, and it can be used even under low temperature conditions of 10°C or lower, especially around 5°C in the working environment. Since the curing reaction progresses sufficiently, a special heating curing oven is not required. Moreover, the physical properties of the cured product at that low temperature are at standard conditions (temperature 20℃,
There is also a feature that there is almost no difference in the physical properties of the cured product at a relative humidity of 65%. The moisture-curable adhesive composition of the present invention is useful for manufacturing various composite panels, such as metals such as base aluminum, stainless steel, galvanized steel sheets, tin plated steel sheets, enameled iron sheets, chemically treated steel sheets, painted steel sheets, and painted aluminum; Used to bond non-porous laminating materials such as tiles and glass with porous materials such as wood, plywood, paper honeycomb core, flexible board, Keical board, and wood wool cement, and cures quickly. Can be glued. The adhesive composition of the present invention can be applied by a conventional method such as a roll coater, a spatula, a combing iron, a hand gun, and the like. Composite panels manufactured using the adhesive composition of the present invention are used for exterior wall panels, interior wall panels, insulation panels, partition panels, etc. in buildings, and are also used for container box frame panels, blackboards for teaching materials, etc. be done. Next, the present invention will be explained in more detail with reference to Examples. Example 1 A polyester polyol (New Ace F7-67, polyester diol manufactured by Asahi Denka Kogyo Co., Ltd., molecular weight 2000) that had been dehydrated overnight with molecular sieves was placed in a 5-volume vertical stirrer that could be sealed and heated to defoam. 100g and polyoxyethylene-propylene polyol (Nyupol)
PL100, polyoxyethylene-propylene diol manufactured by Sanyo Kasei Co., Ltd., molecular weight 2600) 100g was weighed, put in, sealed, heated to 80℃, and added to it with Crude MDI (Sumiyur 44V20, Sumitomo Bayer Co., Ltd.)
(NCO/OH=
6.8/1), replace the air in the container with nitrogen gas, and
A urethane prepolymer (active isocyanate group content: 12% by weight) is obtained by reacting for a period of time. In another sealable hopper-type metal container, add 360 g of Whiten SB (manufactured by Shiroishi Calcium Co., Ltd., heavy calcium carbonate) and Talc LM-R (Tsuchiya Kaolin Kogyo Co., Ltd.).
Water obtained by adding 90g of Talc Co., Ltd.) and drying for 2 hours at 300℃ using a hot air circulation dryer.
Add 0.03% by weight of filler to the above reaction mixture and mix with stirring for 30 minutes. Next, 110 g of di(2-ethylhexyl) phthalate, 45 g of Swasol 310 (manufactured by Nippon Oil Co., Ltd., an organic mixed solvent), 0.1 g of dibutyltin dilaurate, and 5 g of mercaptoalkoxysilane KBM803 (manufactured by Shin-Etsu Chemical Co., Ltd.) were added. , and stirred and mixed for 10 minutes to obtain a moisture-curable adhesive composition [NCO: 47%, viscosity: 12000 cps (measured using a Burckfield viscometer at 20°C]). 25mm width,
150mm length, 0.2mm thickness) and 20℃, 60%RH in advance
A peel test piece was prepared by applying plywood (25 mm width, 100 mm length, 5 mm thickness) that had been humidity-controlled as a bonding material at a coating amount of 150 g/m ² . After curing this test piece at 20℃ for 3 days, 90° peel strength test (Autograph IS2000, crosshead speed 50mm/min)
As a result, the peel strength was 4.2 kg/25 mm. The 90° peel strength of a test piece prepared in the same manner at 5°C and cured for 3 days was 4.0 kg/25 mm. Examples 2 to 7 Moisture-curable adhesive compositions are prepared in the same manner as in Example 1 using the raw materials and blending amounts shown in Table 1. A peel strength test was conducted on this product in the same manner. The results are shown in Table 2. The copolymerization ratio of ethylene oxide in the polyoxyethylene-propylene polyol (Newpol PL-2100) used was 30 mol%. Comparative Example A peel test was similarly conducted using Penguin Semen #1057 (manufactured by Sunstar Giken Co., Ltd.), a conventional two-component epoxy resin adhesive used in the same field.
The results are shown in Table 2.

【table】

【table】

[Table] The relationship between polyoxyethylene-propylene polyols with different ethylene oxide copolymerization ratios (mol%) (hereinafter referred to as EO%), their compatibility with polyester polyols, and the water-resistant adhesive strength in that case is shown below. I conducted an experiment. Experiment After mixing polyoxyethylene-propylene polyol and polyester polyol with various EO% in a 140 c.c. glass bottle at a ratio of 1:1 (weight ratio),
After observing the state of compatibility after several days, this mixed polyol was then used to prepare an adhesive in the same manner as in Example 1, and a water-resistant adhesion test was conducted. The results of such compatibility and water resistant adhesive strength are shown in Table 3.

[Table] From the results in Table 3, it becomes cloudy when the EO% is around 20 mol%, and the compatibility tends to decrease as it approaches 0 mol%.On the other hand, in terms of water-resistant adhesive strength, the EO% is around 20 mol%, and the compatibility tends to decrease. % is found to be appropriate.

Claims (1)

[Scope of Claims] 1. An active isocyanate group-containing urethane prepolymer obtained by reacting a polyester polyol and a polyoxyethylene-propylene polyol mixture containing 20 to 70 mol% of ethylene oxide with an excess of an organic polyisocyanate compound. It consists of an alkoxysilane compound and a filler, and the mixing ratio of polyester polyol and polyoxyethylene-propylene polyol in the above polyol mixture is 8:2 to 2:8.
(weight ratio), and the amount of the above filler is
Moisture-curable adhesive composition characterized in that it is 20-70% by weight. 2. The composition of item 1 above, wherein the urethane prepolymer has an active isocyanate group content of 4 to 15% by weight. 3. The composition of item 1 or 2 above, wherein the organic polyisocyanate compound is diphenylmethane-4,4'-diisocyanate or a derivative thereof. 4. The composition according to item 1 above, wherein the organoalkoxysilane compound is one or more selected from mercaptosilane, epoxysilane, and vinylsilane. 5 The organoalkoxysilane compound is 0.05~
The composition of item 4 above, containing 2.0% by weight. 6. The composition according to item 1 above, wherein the filler is one or more selected from calcium carbonate, talc, clay, carbon, silicic anhydride, and metal powder.