JPH0548252B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a heat-curable polyurethane composition that is industrially useful as a sealant or adhesive. (Prior Art) JP-A-58-120627 discloses a polyurethane composition comprising a liquid aromatic prepolymer and a solid polyhydroxy compound. This composition is a heat-curable one-component polyurethane adhesive composition that cures when heated to 149° C. and has various properties suitable for assembling automobile parts. However, problems have been pointed out with conventional one-component polyurethane adhesives, such as low storage stability in closed containers and the need for curing temperatures of substantially 150° C. or higher. (Problems to be Solved by the Invention) Storage stability in a closed container is an important performance for adhesives and sealants of this type, and its merits and demerits determine the commercial value in the market. Since the curing temperature is used for automobile assembly, it is desired that the curing temperature is below the heat resistance temperature of plastics, that is, 120 to 150°C. It goes without saying that low temperatures are preferable from the point of view of energy and resource conservation. (Means for Solving the Problem) As a result of various studies, the present inventors have found that by coating the surface of a finely ground polyhydroxy compound with wax, the curing temperature is lowered and storage stability is significantly improved. This has made it possible to achieve this, and the present invention has been achieved. In other words, the present invention comprises (1) (a) an organic polyisocyanate compound or a prepolymer having an isocyanate group as a terminal group; and (b) a polyhydroxy compound having two or more active hydrogen atoms in one molecule whose surface is coated with wax. A heat-curable polyurethane composition comprising a solid powder of and having an equivalent ratio of active hydrogen to isocyanate groups of 2.5 to 0.5. (2) (a) an organic polyisocyanate compound or a prepolymer with isocyanate groups as terminal groups; and (b) a solid powder of a polyhydroxy compound having two or more active hydrogen atoms per molecule and whose surface is coated with wax. A heat-curable polyurethane characterized by adding a silicone coupler to a composition having an equivalent ratio of active hydrogen to isocyanate groups of 2.5 to 0.5, or reacting it with isocyanate groups in advance as necessary. Composition of. It is. The organic polyisocyanate compound used in the present invention is an aromatic, aliphatic or alicyclic compound having about two or more isocyanate groups, and is used alone or as a mixture. For example, tolylene diisocyanate (including various mixtures of isomers)
(TDI), diphenylmethane diisocyanate (including mixtures of isomers) (MDI), 3,3'-dimethyl-4,4'-biphenylene diisocyanate (TODI), 1,4-phenylene diisocyanate (PDI) , xylylene diisocyanate (XDI),
Tetramethylxylylene diisocyanate (TMXDI), naphthylene diisocyanate (NDI), dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI), crude TDI, polymethylene polyphenyl isocyanate (crude)
MDI), isophorone diisocyanate (IPDI),
In addition to hexamethylene diisocyanate (HDI) and hydrogenated xylylene diisocyanate (HXDI), these isocyanates are modified into isocyanurates, carbodiimide, and biuret. In particular, it is preferable to use aromatic polyisocyanate compounds alone or in combination. The terminal isocyanate group prepolymer used in the present invention is one obtained by reacting the above-mentioned various organic polyisocyanate compounds with a known polyol by a known method so that free isocyanate groups remain. The polyol used herein is a compound having two or more hydroxyl groups, such as water, polyhydric alcohol such as ethylene glycol, propylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose, propylene oxide or Polyether polyols obtained by addition polymerization of propylene oxide and ethylene oxide, ethylene glycol, propylene glycol and oligoglycols thereof, butylene glycol, hexylene glycol, polytetramethylene ether glycols, polycaprolactone polyols,
These include polyester polyols such as polyethylene adipate, polybutadiene polyols, esters of higher fatty acids containing hydroxyl groups such as castor oil, and polymer polyols obtained by grafting vinyl monomers onto polyether polyols or polyester polyols. The preferred molecular weight range of these polyols is 60 to 8,000. When reacting an organic polyisocyanate compound and a polyol to form a prepolymer, a normal method is used, that is, at room temperature or
React at 120℃. The ratio of organic polyisocyanate to polyol may be about 1.2 to 3.5 in terms of equivalent ratio. The NCO% of the prepolymer is 1 to 35% by weight. The viscosity of the obtained prepolymer is preferably in the range of 100 to 100,000 centipoise from the viewpoint of compounding operations, and for this purpose a plasticizer, a solvent containing no active hydrogen, etc. may be added. The polyhydroxy compound having two or more active hydrogen atoms in one molecule used in the present invention is a polyhydroxy compound, preferably a polyhydroxy compound that is solid at room temperature. For example, isopropylidene-bis(β-hydroxyethoxyphenol) (bisphenol
A compound with 2 moles of ethylene oxide added to 1 mole of A (BPA・2EO), 1,4-di(β-hydroxyethoxy)phenol (a compound with 2 moles of ethylene oxide added to 1 mole of hydroquinone,
HQ・2EO), pentaerythritol, dipentaerythritol, tripentaerythritol and mixtures thereof, neopentyl glycol [2,2-bis(hydroxymethyl)1,3propanediol], and the like. The waxes used in the present invention include petroleum waxes, polyethylene waxes, natural waxes, oxidized waxes, and synthetic waxes, among which waxes with a melting point of 60 to 120°C are preferred. If the melting point is too high above this range, the curing temperature will be high, and if it is too low below this range, storage stability will deteriorate. The coating amount of wax is preferably 3 to 30% by weight of the polyhydroxy compound. If the amount exceeds this amount, the adhesiveness of the polyurethane composition will decrease, and if the amount is less than this amount, the storage stability will deteriorate. In order to produce the heat-curable polyurethane composition of the present invention, the surface of the finely pulverized polyhydroxy compound is coated with a CF-granulation coating device, SPIR-A-
Wax is coated using a device such as FLOW or counter jet mill, and this and a prepolymer with terminal isocyanate groups are combined with hydroxy groups/
Blend so that the equivalent ratio of isocyanate groups is 2.5 to 0.5. In this case more than 2.5 and 0.5
If it is less than that, the necessary physical properties will not be sufficiently developed after curing. In this case, the plasticizer is blended in an amount of 0 to 30% by weight based on the total amount of the composition. Plasticizers are added to reduce viscosity and facilitate workability. Plasticizers used include di-2-ethylhexyl phthalate (DOP), dibutyl phthalate (DBP), diisodecyl phthalate (DIDP), di-2-ethylhexyl adipate (DOA), and tricresyl phosphate (TCP). A normal one is fine. Further, during compounding, molecular sieve, calcium oxide, or activated alumina is added as an intersystem water binder in an amount of 1 to 10% by weight based on the total amount of the composition.
If necessary, a silicone coupler is added in an amount of 0.1 to 5% by weight based on the total amount of the composition. A Dalton mixer is used as a compounding machine, and the mixture is mixed and defoamed for 1 hour at room temperature to form a product. The above silicone couplers include γ-glycidoxypropyltrimethoxysilane (A-187), γ-mercaptopropyltrimethoxysilane (A-189), or γ-aminopropyltrimethoxysilane (A-1100) [all Union Carbide Products] is suitable. Here, depending on the reactivity of the NCO group present in the reaction system, reaction conditions, etc., the silicone couplers used can be reacted with each other in advance. The product can be heated to about 10~120℃ by heating to 60~120℃.
Hardens in 30 minutes. (Example) Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. Example 1 The surface of 1 kg of finely ground HQ-2EO was coated with paraffin wax 155P (melting point 68.3 to 71.0°C) using a counter jet mill. The amount of adhesion is
It was 100g. This was designated as A-1. A propylene oxide adduct of glycerin with a molecular weight of 1500 (MN-1500 manufactured by Mitsui Nisso Urethane) was placed in a four-necked flask equipped with an inlet, a nitrogen inlet, a stirrer, and a thermometer under a nitrogen stream. )
1500g (1 mol) was added and the internal temperature was maintained at 45°C.
Next, 1500 g of MDI (6
mole) was added. The reaction was carried out for 2 hours while keeping the internal temperature at 80°C while paying attention to the heat generated by the reaction. N.C.O.
A prepolymer (Pre-1) having a weight % of 12.5 and a viscosity of 7000 cps/25°C was obtained. 5 Daiton mixer (Pre-1) 1000g
(2.976 equivalents), (A-1) 327 g (3.003 equivalents), 150 g of diisodecyl phthalate, and 50 g of Molecular Sieves 3A (manufactured by Union Carbide),
After mixing at room temperature for about 1 hour and defoaming, a product was obtained. The product did not gel for 4 weeks at 50°C, indicating good storage stability. Example 2 In the final formulation step of Example 1, 7 g of γ-glycidoxypropyltrimethoxysilane was added,
A product was obtained by blending in the same manner as above. Product temperature is 50℃
No gelation occurred for 4 weeks, indicating good storage stability. Example 3 The surface of 1 kg of finely pulverized BPA・2EO was coated with Micro Wax 180M (melting point 82.1-87.8°C) using a counter jet mill. The amount of adhesion is
It was 103g. This was designated as A-2. Obtained in Example 1 using a Dalton mixer of 5 (Pre-1)
1000g (2.976 equivalents), (A-2) 470g (3 equivalents),
Add 200 g of diisodecyl phthalate, 50 g of Molecular Jeeves 3A, and 5 g of γ-glycidoxypropylmethoxysilane, and mix at room temperature for about 1 hour.
After defoaming, a product was obtained. The product did not gel for 4 weeks at 50°C and showed excellent storage stability. Comparative Example 1 A product was obtained in the same manner as in Example 1 except that 297 g (3.00 equivalents) of finely pulverized HQ-2EO was used instead of A-1. Comparative Example 2 A product was obtained in the same manner as in Example 1 except that 102 g (3.00 equivalents) of finely pulverized pentaerythritol was used instead of A-1.

【table】

[Table] (Effects of the Invention) Examples 1, 2 and 3 exhibited better storage stability than Comparative Example 1. Furthermore, compared to Comparative Example 2, it exhibited low adhesive strength, curing temperature, and good storage stability. The adhesive strength showed the same or better results than the comparative example, but in particular, Examples 2 and 3 using a silane coupler had significantly superior adhesive retention after boiling.

Claims (1)

[Scope of Claims] 1. (a) A solid of an organic polyisocyanate compound or a prepolymer having an isocyanate group as a terminal group and (b) a polyhydroxy compound having two or more active hydrogens per molecule whose surface is coated with wax. A heat-curable polyurethane composition comprising powder and having an equivalent ratio of active hydrogen to isocyanate groups of 2.5 to 0.5. 2. Consisting of (a) an organic polyisocyanate compound or a prepolymer with isocyanate groups as terminal groups, and (b) a solid powder of a polyhydroxy compound whose surface is coated with wax and has two or more active hydrogen atoms per molecule. A heat-curable polyurethane composition in which a silicone coupler is added to a composition having an equivalent ratio of hydrogen to isocyanate groups of 2.5 to 0.5.