JPH10158353A - One-pack type thermosetting urethane composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a one-pack type thermosetting urethane composition excellent in both storage stability and low-temperature curing (baking) performance. SOLUTION: This one-pack type thermosetting urethane composition comprises (A) an NCO group block body of an end active NCO group-containing urethane prepolymer and/or an NCO block body of a polyisocyanate compound and (B) a fine powder-coated amine obtained by coating the surface of a solid amine having <=20μm central particle diameter with fine powder having <=2μm central particle diameter in the weight ratio of the solid amine/the fine powder of 1/0.001-0.5 to coat the active amino group on the surface.

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 thermosetting urethane composition, and more particularly, to an isocyanate component in which isocyanate (NCO) groups are blocked, for example, an NCO group-blocked urethane prepolymer containing a terminally active NCO group. It is composed of an amine component coated with an amino group and has excellent storage stability (extremely less aging) and good baking properties.It is mainly useful as a thermosetting sealing material, coating material, adhesive, etc. NCO to regenerate
The present invention relates to a one-pack type thermosetting urethane composition utilizing a reaction curing of a group and an active amino group generated by heating and melting.

[0002]

BACKGROUND OF THE INVENTION Urethane compositions of this kind, such as thermosetting sealants, are commonly used in structures that are produced in a continuous assembly line.
For example, when a press-formed steel plate is assembled by partial welding such as spot welding in a production line such as an automobile or a refrigerator, it is used to seal joints and gaps in order to maintain airtightness and watertightness. The structure assembled by partial welding such as spot welding is subjected to base treatment and electrodeposition coating for the purpose of rust prevention, then a thermosetting sealing material is applied to a predetermined part, and then used for aesthetic purposes The sealing material can be cured at the same time as the baking of the intermediate coating and the top coating. For such use, it is extremely advantageous to use a one-part type thermosetting sealing material which does not require metering and mixing and has no limitation on pot life.

[0003] As such a one-part type thermosetting sealing material, there has hitherto been used a PVC paste composition in which polyvinyl chloride (PVC) powder is dispersed in a plasticizer and an adhesive, a stabilizer, a filler and the like are blended. A material, that is, a so-called PVC plastisol-based sealing material has been frequently used. This PVC
Although the plastisol-based sealing material does not involve a chemical thermosetting reaction, the PVC powder absorbs the plasticizer due to heat, solidifies and gels with each other, and hardens apparently,
It has various disadvantages as described below. 1) Since the main component is PVC, it is easily decomposed by heat, light, and the like, and generates hydrogen chloride at the time of decomposition, and easily causes rust and corrosion on the base steel sheet. 2) Because the main component is PVC, it tends to be hard and brittle at low temperatures,
Cracks and peeling may occur due to external force such as vibration and impact, and strain. 3) Poor adhesion to the electrodeposited surface, which is the usual adhesion substrate, requires the use of a special adhesion-imparting agent, but the adhesion-imparting agent may accelerate the aging of the sealing material.

On the other hand, as other sealing materials, epoxy-based sealing materials comprising an epoxy resin and a latent curing agent, and rubber-based sealing materials comprising a diene rubber, a vulcanizing agent and a vulcanization accelerator have been partially used. However, an epoxy-based sealing material tends to be distorted or cracked due to lack of flexibility that cannot follow displacement, and a rubber-based sealing material may cause paint contamination due to a vulcanizing agent.

[0005]

The present inventors have conducted various studies to obtain a one-pack type thermosetting sealing material free from such disadvantages. First, an isocyanate component in which an NCO group is blocked is used. Examination of the combination of the curing reaction between the product and the so-called active hydrogen compound revealed that the combination of ordinary polyamine compounds cured but had poor storage stability; and the combination of ordinary polyol compounds showed good storage stability. Some were found to be poor in curability. Furthermore, the block itself of the isocyanate component itself was examined by changing the type of the polyisocyanate compound or the blocking agent as the raw material,
There was no one that could achieve both curability and storage stability.

Therefore, regarding the combination of the above curing reactions,
As a result of further intensive studies, they have found that by combining an amine component coated with an amino group, it is possible to achieve both low-temperature curability and storage stability. In this combination, when a non-blocked isocyanate component is used, the curing proceeds sufficiently in the presence of atmospheric moisture (moisture).・ Moisture management (ii) Product container and discharge condition management (iii) Water management at the time of use (use of a pump with high sealability, countermeasures for hardening of the nozzle tip, etc.) was required.

That is, the present invention relates to (A) an NCO of a urethane prepolymer containing a terminally active isocyanate (NCO) group.
Base block and / or NCO group block of polyisocyanate compound; and (B) a fine powder having a central particle diameter of 2 μm or less is coated on the surface of a solid amine having a central particle diameter of 20 μm or less by weight ratio of the solid amine to the fine powder. Is 1 / 0.001-
An object of the present invention is to provide a one-part type thermosetting urethane composition comprising, as a main component, a fine powder coating amine coated with active amino groups on the surface, which is fixed to 0.5.

[0008] In the present invention, the NCO group block of the urethane prepolymer containing a terminally active NCO group (hereinafter referred to as NCO block prepolymer), which is the component (A) (isocyanate component), refers to an excess amount of various polyol components. The reactive NCO group-containing urethane prepolymer obtained by reacting the polyisocyanate compound with a blocking agent is reacted to mask the active NCO group.

[0009] Examples of the polyol component include ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol,
Polyoxyalkylene ether polyols obtained by addition polymerization of propylene oxide or propylene oxide and an alkylene oxide such as ethylene oxide to polyhydric alcohols such as sorbitol and sucrose; ethylene glycol, propylene glycol and their oligoglycols; butylene glycol, Xylene glycol, polytetramethylene ether glycols; polycaprolactone polyols; polyester polyols such as polyethylene adipate; polybutadiene polyols; higher fatty acid esters having a hydroxyl group such as castor oil; polyether polyols or polyester polyols And polymer polyols in which a vinyl monomer is grafted. Usually, one molecule has 2 to 3 hydroxyl groups, and has a hydroxyl equivalent of 500
~ 3000 polyoxyalkylene ether polyols are preferred.

The polyisocyanate compound includes:
Any belonging to the aromatic, aliphatic or cycloaliphatic may be used, for example tolylene diisocyanate (TD
I), diphenylmethane diisocyanate (MDI), 3,
3'-dimethyl-4,4'-biphenylene diisocyanate, 1,4-phenylene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, naphthylene diisocyanate, norbornane diisocyanate (NBDI), dicyclohexylmethane-
4,4'-diisocyanate, crude TDI, polymethylene polyphenylisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 2,2,4-trimethyl-1,6 −
Hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) -cyclohexane, hydrogenated xylylene diisocyanate, isocyanurates thereof, carbodiimidates, burettes, and the like, and one or a mixture of two or more thereof can be used. May be used for use. The reaction between the polyol component and the polyisocyanate compound is usually carried out at a ratio such that the former OH group / the latter NCO group (equivalent ratio) is 1 / 1.2 to 3.5, and if necessary, an appropriate reaction solvent. (E.g., ethyl acetate, toluene, xylene) and reaction catalysts (e.g., organotin-based catalysts such as dibutyltin dilaurate, bismuth-based catalysts such as bismuth octylate, and 1,3-diaza [2.2.2] bicyclooctane). Grade amine catalyst), usually at room temperature to 60 to 90
C. for 1 to 7 hours.

Examples of the blocking agent include phenols (phenol, cresol, xylenol, ethylphenol, etc.), lactams (ε-caprolactam, δ-valerolactam, β-butyrolactam, β-propiolactam, etc.), oximes System (formamide oxime, acetamidooxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexanone oxime, etc.), active methylene system (diethyl malonate, dimethyl malonate,
Ethyl acetoacetate, methyl acetoacetate, acetylacetone, etc.), alcohols (methanol, ethanol, propanol, isopropanol, butanol, 2-ethylhexanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, etc.), benzotriazole And mercaptans, acid amides, imides, amines, imidazoles, ureas and the like, with phenols, lactams and oximes being particularly preferred.

A blocking agent is required for the terminally active NCO group-containing urethane prepolymer in such a ratio that the former NCO group / the latter active hydrogen group (equivalent ratio) is usually 0.9 to 1.05. In the presence of a suitable organic solvent (for example, an ester type, ether type, ketone type, aromatic type, etc. having no active hydrogen) and an organic metal such as tin, zinc, lead and a catalyst such as a tertiary amine, By reacting at 100 ° C. for 1 to 3 hours, an NCO block prepolymer masking active NCO groups can be obtained.

In the present invention, the above-mentioned NCO is used as the component (A).
An NCO group block of a polyisocyanate compound that can be used in place of or in combination with a block prepolymer (hereinafter, referred to as an NCO block compound) refers to an active NCO group of the polyisocyanate compound, In the same manner as in the case, the one masked with the blocking agent is referred to.

The component (B) (amine component) in the present invention.
The fine powder coating amine is, while pulverizing the solid amine to a predetermined center particle size range, simultaneously adding a fine powder thereto and mixing and pulverizing such that the fine powder has a predetermined center particle size range, It is manufactured by a shear friction type mixing method in which fine powder is fixed on the surface of an amine. Further, by using a high-speed impact type mixing stirrer or a compression shearing type mixing stirrer together with the finely divided solid amine which has been finely pulverized in advance, a fine powder coating amine can be produced.
In particular, a case where a high-speed impact type mixing stirrer is used is more preferable. As the solid amine, any one belonging to aromatic or aliphatic groups may be used. For example, 4,4′-diaminodiphenylmethane, 2,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,4 '-
Diaminodiphenylmethane, 2,2'-diaminobiphenyl, 2,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,4-diaminophenol, 2,5-diaminophenol, o-phenylenediamine, m-phenylenediamine Aromatics such as 2,3-tolylenediamine, 2,4-tolylenediamine, 2,5-tolylenediamine, 2,6-tolylenediamine, and 3,4-tolylenediamine; 1,1
2-dodecanediamine, 1,10-decanediamine, 1,
Aliphatic such as 8-octanediamine, 1,14-tetradecanediamine, and 1,16-hexadecanediamine may be mentioned, and one or a mixture of two or more thereof may be used. The solid amine is adjusted to have a central particle size of 20 μm or less, preferably 3 to 15 μm. If the center particle size exceeds 20 μm, the heat-cured polyurethane will undergo incomplete reaction curing, and the desired physical properties will not be obtained.

As the fine powder, any of inorganic or organic powders can be used. For example, titanium oxide, calcium carbonate, clay, silica, zirconia, carbon, alumina, talc, etc. Examples of the system include polyvinyl chloride, polyacrylic resin, polystyrene, polyethylene and the like.
A mixture of more than one species is ready for use. The amount used is selected such that the weight ratio of the solid amine to the fine powder is 1 / 0.001 to 0.5, preferably 1 / 0.002 to 0.4. If the ratio of the fine powder is less than 0.001, the effect of storage stability is not recognized, and if it exceeds 0.5, the storage stability is not further improved. By mixing and grinding the solid amine and the fine powder in this way, static electricity is generated and the fine powder adheres to the surface of the solid amine, or friction, impact, compression shear, etc. generated by the mechanical force of the mixing stirrer. It is predicted that the fine powder will stick due to the local melting and sticking phenomenon of the solid amine due to the heat generated by the solid amine, or that it will be physically anchored or embedded in the surface of the solid amine, or that it will be chemically activated and stick. (Ie, the active amino groups (NH ₂ ) on the surface of the solid amine are covered with the fine powder). It is important that the center particle size of the fixed fine powder is set to 2 μm or less, preferably 1 μm or less, and if it exceeds 2 μm, it will not be fixed to the surface of the solid amine. Such fine powder coating amine,
Although it acts as a curing agent for the isocyanate component (A), it may be further reacted with a liquid isocyanate compound (usually at a temperature lower than the melting point) to deactivate the remaining active amino groups.

The liquid isocyanate compound includes:
For example, crude MDI, p-toluenesulfonyl isocyanate, isophorone diisocyanate, TDI, n
-Octadecyl isocyanate. The ratio of the liquid isocyanate compound is usually NH _{2 of} the solid amine.
And an equivalent ratio of NCO to 1 / 0.01 to 0.5. By the deactivation treatment with the liquid isocyanate compound, the storage stability is further improved as compared with the case of only the coating treatment with the fine powder. In addition,
In the above equivalent ratio, when NCO is less than 0.01,
The desired effect of improving the storage stability cannot be obtained, and if it exceeds 0.5, further improvement in the storage stability tends not to be obtained. As described above, the fine powder coating amine (B) obtained by the coating treatment with the fine powder and the deactivation treatment with the liquid isocyanate compound if necessary is activated at the curing temperature (usually 60 to 100 ° C.), and after the heat activation, The NH ₂ present takes part in the curing reaction of the isocyanate component (A) with the NCO. Therefore, the mixing ratio of the two components (A) and (B) is usually such that the equivalent ratio of NH ₂ and NCO after the heat activation is 1
/0.5 to 2.0.

The one-pack type thermosetting urethane composition according to the present invention is a system in which the above-mentioned NCO block prepolymer and / or NCO block compound (isocyanate component (A)) and fine powder coating amine (B) are blended. If necessary, a bifunctional or more epoxy resin may be added as a component (C) in an appropriate amount in order to impart physical properties of the cured product, particularly, tough durability against compression set and the like.
As the epoxy resin, bisphenol A type, F type,
AD type, phenol type, cresol type, cycloaliphatic,
Glycidyl esters, glycidylamines and the like can be mentioned, and liquid ones are particularly preferable. Such epoxy resin
The addition of (C) allows the epoxy resin to react with the isocyanate component (A) and the solid amine during heat curing.
The reaction between (C) and the solid amine takes place, and a network structure is formed based on the three-dimensional reaction, so that a cured product having the above-mentioned tough durability can be formed. Epoxy resin
(C) is usually used in an amount of 1 to 15 parts with respect to 100 parts (parts by weight, hereinafter the same) of the isocyanate component (A). 1
If the amount is less than 15 parts, the physical properties of the epoxy resin (C) cannot be expected. If the amount exceeds 15 parts, the rubber physical properties of the cured polyurethane product are impaired. When the physical properties of the epoxy resin (C) are desired, the epoxy resin (C) can be made rich. If necessary, a conventional additive such as a urethane catalyst, a solvent (for example, a solvent having a small polarity such as an aliphatic hydrocarbon, an aromatic hydrocarbon, an alicyclic hydrocarbon, a halogenated hydrocarbon, or an ether) , Esters, ketones and the like, and particularly preferred are aliphatic hydrocarbon solvents), plasticizers (e.g., dibutyl phthalate, di (2-ethylhexyl) phthalate, dioctyl phthalate, dicyclohexyl phthalate, diisooctyl phthalate, Diisodecyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, trioctyl phosphate, epoxy plasticizer, toluene-sulfonamide, chloroparaffin, adipate, etc.), filler, thixotropic agent, ultraviolet absorber, antioxidant, dye An appropriate amount of pigment, adhesive, dehydrating agent, etc. may be blended In addition, DBU [1,8-diazabicyclo] is used as the urethane catalyst.
(5.4.0) undecene-7], a DBU phenol salt,
DBUs such as DBU octylate and DBU formate; monoamines (such as triethylamine), diamines (N, N, N ′,
N'-tetramethylethylenediamine, etc.), triamine
Amines such as (e.g., tetramethylguanidine), cyclic amines (e.g., triethylenediamine), alcoholamines (e.g., dimethylaminomethanol), and etheramines (e.g., bis (2-dimethylaminoethyl) ether); Sn-based (dibutyltin dilaurate, Organic carboxylate metal salts such as tin octylate), Pb type (lead octylate) and Zn type (zinc octylate); and imidazole type such as 2-methylimidazole and 1,2-dimethylimidazole.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The composition of the present invention having the above constitution is useful mainly as a thermosetting sealing material in production lines of automobiles and the like, and is applied to other adhesives, coating materials, molded articles and the like. Is also possible. In addition, it is possible to form an excellent cured product which is excellent in storage stability (invariability over time) and low-temperature curability in a closed container and has rubber properties.

[0019]

EXAMPLES Next, Production Examples, Examples and Comparative Examples will be given.
The present invention will be described more specifically. Production Example 1 (Production of NCO block prepolymer) Tolylene diisocyanate (TDI) was added to polyoxypropylene diol having a hydroxyl equivalent of 1500, and OH group / N
The reaction is carried out at 80 ° C. for 2 hours at an equivalent ratio of CO group = 1 / 2.2 to obtain a urethane prepolymer containing a terminally active NCO group. Then, ε-caprolactam or ethylphenol was added as a blocking agent to the NCO group / active hydrogen group (equivalent ratio).
At a rate of 50 ° C. for ethylphenol or 80 ° C. for 2 hours for ε-caprolactam to obtain lactam-based and phenol-based NCO block prepolymers, respectively. Production Example 2 (Production of fine powder coating amine) 1,12-dodecanediamine having a center particle size of about 8 μm (melting point: 7
(1 ° C.) 76.9 parts and 23.1 parts of ultrafine titanium oxide particles having a center particle diameter of about 0.02 μm are mixed, and subjected to a compounding treatment with a Hi-X mixer (manufactured by Nisshin Engineering Co., Ltd.), whereby A fine powder coating amine having a center particle size of about 8 μm is obtained.

Examples 1 and 2 and Comparative Examples 1 to 4 Each component having the number of parts shown in the following Table 1 was blended and mixed and dispersed with a chem stirrer to prepare a one-pack type thermosetting urethane composition. Performance test (1) Storage stability The compositions of Examples 1 and 2 and Comparative Examples 1 to 4 were respectively
Store tightly closed at 40 ° C., measure the increased viscosity after 7 days,
Table 1 also shows the results of comparison with the initial viscosity immediately before storage. :: Viscosity change rate of less than 50% ×: ５０ 50 to 100% XX: ＞> 100% (2) Room temperature storage properties The compositions of Examples 1 and 2 and Comparative Examples 1 to 4 were respectively
Apply in the form of a semicircular bead of 100 × 10mmφ, 20 ℃ ×
It was left under the condition of 65% RH, and the life (whether or not gelled) was checked for shape retention by finger touch. The results are also shown in Table 1. :: No shape retention within 3 days ×: Shape retention within 3 days or more (3) Baking properties The compositions of Examples 1 and 2 and Comparative Examples 1 to 4 were respectively
After coating on a release paper at a dry film thickness of 2 mm and baking and curing under three conditions, the curability and adhesion of the cured film to be formed are determined, and the results are also shown in Table 1. Curability ○: rubber elasticity, no tack △: rubber elasticity, tacky ×: uncured adhesive ○: cohesive failure ×: interface failure

[0021]

[Table 1] * 1) Calcium carbonate surface-treated with fatty acids * 2) Heavy calcium carbonate

[0022]

From the results shown in Table 1, it is recognized that the compositions of the present invention of Examples 1 and 2 can achieve both storage stability and low-temperature curability. In addition, the composition of the present invention exhibits good results of room temperature storage properties (life evaluation after storage at room temperature),
For example, it is expected that skinning and hardening reaction at room temperature and high humidity in the summer can be suppressed, and it is recognized that even in handling under rough air for several days, a stable state can be maintained without hardening.

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI C09J 175/04 C09J 175/04 C09K 3/10 C09K 3/10 D

Claims (3)

[Claims] 1. A surface of (A) an NCO group block of a urethane prepolymer containing a terminally active isocyanate (NCO) group and / or an NCO group block of a polyisocyanate compound; and (B) a solid amine having a central particle diameter of 20 μm or less. A fine powder having a center particle size of 2 μm or less is fixed so that the weight ratio of the solid amine to the fine powder is 1 / 0.001 to 0.5, and the active amino group on the surface is coated. A one-component thermosetting urethane composition comprising an amine as a main component. 2. The compounding ratio of component (A) to component (B) is such that the equivalent ratio of amino group to NCO group after heat activation is 1 / 0.5 to
The one-part thermosetting urethane composition according to claim 1, which is selected to be 2.0. 3. The fine powder coating amine of the component (B) is further reacted with a liquid isocyanate compound,
The remaining active amino groups are inactivated, and the ratio of the liquid isocyanate compound is selected such that the equivalent ratio of amino groups to NCO groups of the solid amine is 1 / 0.01 to 0.5. 3. The one-component thermosetting urethane composition according to 1 or 2.