JPH038371B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing urethane resin. More specifically, the present invention relates to a method for producing a water-swellable urethane resin that absorbs water and swells to about 10 to 20 times its own weight when it comes into contact with water. Water-swellable resins are used as fillers, caulking materials, coating materials, sealants, dry sheets, etc. in civil engineering and construction work. As such a water-swellable resin, there is one in which an oxyethylene/oxypropylene copolymer polyether polyol and a polyisocyanate are reacted at an NCO/OH ratio in the vicinity of equivalents. However, this material has low swelling properties in water and seawater, and is difficult to use in places where large swelling properties are required. The present inventors have made extensive studies aimed at solving the above-mentioned drawbacks, and as a result, have arrived at the present invention. That is, the present invention uses a polyether polyol (a) and an organic polyisocyanate (b) having a urethane prepolymer [A] and a polyether polyol [B] having isocyanate groups at the terminals, and a catalyst at an NCO/OH ratio of 2.1 to 4. This is a method for producing a water-swellable urethane resin, which is characterized by reacting and curing in the presence of a water-swellable urethane resin. Examples of the polyether polyol (a) in the present invention include oxyethylene/oxypropylene copolymer polyether polyols (hereinafter sometimes referred to as copolymers). Such polyether polyols include ethylene oxide (hereinafter referred to as ethylene oxide), a compound containing active hydrogen (OH group, amino group, etc.).
EO) and propylene oxide (hereinafter referred to as
An example of this is an adduct (called PO). For example, polyhydric alcohols [dihydric alcohols (ethylene glycol, propylene glycol, etc.); trihydric or higher, usually trihydric to octahydric alcohols (glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose, etc.)]; polyhydric alcohols; Phenols [hydroquinone, resorcinol, catechol, bisphenols (bisphenol A, etc.), etc.];
Amines [monoamines (mono- or di-alkylamines, cyclohexylamine, morpholine, etc.), alkanolamines (mono-, di- or tri-ethanolamine, n- or iso-propanolamine, etc.), (poly)alkylene polyamines (ethylene diamine) EO and PO adducts (random or block adducts,
Random adducts) are preferred. Preferred among these are the EO and PO adducts of polyhydric alcohols, especially ethylene glycol, propylene glycol and glycerin. The oxyethylene content in the copolymer is usually 50 to 50% of the total weight of oxyethylene and oxypropylene.
90%, preferably 60-85%. If the oxyethylene content is less than 50%, the water swelling rate will be insufficient, and the water swelling rate will be 90%.
When the amount increases, the shape retention of the water-swellable resin in water decreases. The hydroxyl equivalent of the copolymer is usually 1,000 to 4,000, preferably 2,000 to 3,000. If it is less than 100, the swelling ratio will be insufficient, and if it exceeds 4000, the shape retention will decrease.
In addition, the average number of functional groups per molecule of the copolymer is usually
2 to 2.5, preferably 2 to 2.2. When the average number of functional groups is greater than 2.5, crosslinking occurs and water swelling property decreases. In the present invention, it is preferable to use the oxyethylene/oxypropylene copolymer polyether polyol as the polyether polyol, but a combination of polyethylene polyol and polypropylene polyol may also be used. In this case, the oxyethylene content in the combined product is usually 50 to 90% of the total weight of oxyethylene and oxypropylene, and 60 to 85% of the total weight of oxyethylene and oxypropylene.
% is preferable. Furthermore, the hydroxyl value and average number of functional groups per molecule of the combination product are usually the same as in the case of the above-mentioned copolymer. Examples of the organic polyisocyanate (b) in the present invention include aromatic polyisocyanates [tolylene diisocyanate (hereinafter referred to as TDI), 4,4'-diphenylmethane diisocyanate (hereinafter referred to as MDI), crude MDI, xylylene diisocyanate, etc.], modified Polyisocyanate [For example, polyisocyanate (MDI, etc.) with carbodiimide group,
Polyisocyanate modified to contain uretdione groups and uretonimine groups (Japanese Patent Publication No. 1986-
Publication No. 8968, Special Publication No. 55-27098, Special Publication No. 1977
-33597, etc.)] For example, Isonate 143L (manufactured by Kasei Upjiyon), Millionate MTL (manufactured by Hodogaya Chemical), and Sumidyur.
Examples include PF, CD (manufactured by Sumitomo Bayer Urethane), alicyclic polyisocyanates (hydrogenated MDI, hydrogenated TDI, isophorone diisocyanate, etc.), aliphatic polyisocyanates (hexamethylene diisocyanate, etc.), and mixtures of two or more of these. . Also, excess polyisocyanate (TDI,
Free isocyanate-containing prepolymers obtained by reacting polyols (such as trimethylolpropane, 1,4-butanediol, etc.) with polyols (such as MDI) can also be used. In the urethane prepolymer [A] having isocyanate groups at the ends of (a) and (b), the ratio in which (a) and (b) are reacted is usually 2 to 2 in terms of NCO/OH ratio.
8, preferably 2.5 to 5. When obtaining the urethane prepolymer [A], the reaction temperature is usually 60 to 100°C, preferably 70 to 90°C, and the reaction time is usually 3 to 12 hours, preferably 4 to 8 hours. The prepolymerization reaction can also be carried out in a solvent depending on the case. Examples of this solvent include polar solvents that do not have active hydrogen, such as ketone solvents (methyl ethyl ketone, methyl isobutyl ketone, etc.), ester solvents (methyl acetate, ethyl acetate, etc.), cellosolve solvents (methyl cellosolve, etc.), and two types thereof. Examples include mixtures of the above. The NCO% of the obtained urethane prepolymer (A) is usually 2 to 7%, preferably 3 to 6%. Polyether polyol [B] in the present invention
Examples of the polyether polyol include the same polyether polyols as the above-mentioned polyether polyol (a), and preferred ones are also the same. Catalysts used in the present invention include catalysts that promote the reaction between NCO and hydroxyl groups or water, such as tin-based catalysts (dibutyltin dilaurate, stannous octoate, etc.), lead-based catalysts (lead octoate, lead naphthenate, etc.), and amines. Examples include system catalysts (1.4-diaza-bicyclo[2,2,2]octane, 1.8-diaza-bicyclo[5,4,0]undecene-7, triethylamine, N-ethylmorpholine, etc.). Among these, preferred are tin-based catalysts and lead-based catalysts. When producing a water-swellable urethane resin by reacting and curing [A] and [B] in the presence of a catalyst,
The NCO/OH ratio of [A] and [B] is usually 2.1~
4, preferably 2.1 to 3.7, particularly preferably 2.2 to
It is 3.3. If the NCO/OH ratio is less than 2.1, the physical strength and shape retention during water swelling will be poor, the curing will be easily affected by moisture in the atmosphere, the reproducibility of water swelling ability will be poor, and the curing will not progress sufficiently. It has drawbacks such as: Furthermore, if the NCO/OH ratio is greater than 4, problems such as a lower degree of water swelling (lower water absorption) and a tendency to foam during curing result in a decrease in physical strength when swollen with water. . The amount of catalyst is usually 0.01% to 2%, preferably 0.05% to 1%, based on the water-swellable urethane resin. The reaction and curing may be carried out without the presence of a solvent, but may be carried out in the presence of a solvent if necessary in order to improve workability. In this case, the solid content concentration in the system is usually 60 to 100% by weight. When a solvent is used, the same solvents as those described for the urethane prepolymerization reaction can be mentioned. Also, dilution with solvent is [A], [B] and/
Or, even if you add a solvent to the catalyst in advance,
Further, a solvent may be added to the mixture of [A], [B] and the catalyst. The reaction and curing conditions are usually 4 to 36 hours at room temperature and 2 to 6 hours at 50°C. In addition, when manufacturing urethane resin, fillers (talc, bentonite, calcium carbonate, lithopone, silica, mica, etc.), colorants (pigments (titanium white, red iron, carbon black, chrome green, etc.)), ultraviolet absorbers, antioxidants, etc. It is also possible to add agents, plasticizers (DOP, DBP, etc.), anti-sagging agents (ultrafine powdered silica, asbestos, etc.). In the case of a filler, the amount added is 0 to 60%, preferably 0 to 25%, based on the urethane resin. In addition, water-insoluble water-absorbing resin (JP-A-52-
No. 149190, JP-A-51-125468, JP-A-52-
Water-insoluble monomers and/or monomers that become water-soluble upon hydrolysis (A)' and starch and/or cellulose (B)' and/or It is also possible to add a polymer obtained by polymerizing the crosslinking agent (C)' as an essential component and hydrolyzing it if necessary. When producing a urethane resin by reacting and curing [A] and [B] in the presence of a catalyst, the urethane resin may be produced on the substrate by applying it to the substrate, or the urethane resin may be produced on the substrate without being applied to the substrate. It may also be a molded product. When applied to basics, the substrates include metals (iron, tin, galvanized iron, aluminum, etc.), concrete, mortar, wood, slate, glass, etc. A primer is usually used when the applied substrate is metal. This primer is an NCO-excess urethane prepolymer obtained by reacting a polyisocyanate component with an active hydrogen component consisting of an oxyalkylene ether of bisphenols and, if necessary, a polyhydric alcohol and a polymeric polyol. Patent application ``Primer composition'' dated June 25, 2017 and those described in Japanese Patent Application No. 187353/1983), an NCO component consisting of polymethylene polyphenyl polyisocyanate, oxyalkylene ether of bisphenols, and low-molecular polyol if necessary. and an active hydrogen component consisting of a polymeric polyol (patent application)
No. 55-120318, No. 168310 and No. 168311
) can be mentioned. Among these, the former is preferred. Other normal moisture-curing NCO
Urethane prepolymer [active hydrogen consisting of high molecular polyol (polypropylene glycol, etc.) and, if necessary, low molecular polyol (ethylene glycol, 1,4-butanediol, glycerin, trimethylolpropane, pentaerythritol, polypropylene glycol (molecular weight 400 or less), etc.) A prepolymer obtained by reacting an NCO component consisting of a polyisocyanate with an excess of NCO groups, and the NCO% is usually 3 to 15%] can also be used. Examples of methods for applying raw materials such as [A] and [B] to the substrate include spraying, brushing, roller coating, spatula application, application with a caulking gun, and trowel application. The amount of coating in this case is not particularly limited, but is usually 100 g/m 2 to 5000 g/m <sup>2</sup> . The film thickness is usually 10μ or more, preferably 100μ to 5μ.
mm. According to the invention, (A) and (B) are cured by reacting in the atmosphere. It is preferable to cause [A] to react with [B] and at the same time to react with moisture in the atmosphere to effect moisture curing. The urethane resin produced according to the present invention has the property of swelling to about 10 to 20 times its own weight (1000 to 2000%) when immersed in water, seawater, hard water, water containing metal ions, etc. The urethane resin produced according to the present invention has high water swelling properties as described above. Moreover, the degree of swelling does not decrease even in seawater, hard water, or water containing metal ions such as sodium, calcium, and iron, which has been considered difficult until now, and is comparable to that in pure water. In addition to the above-mentioned effects, the urethane resin produced by the present invention has good adhesion to the substrate, does not peel off or fall off when swollen with water, and does not reduce its water-swelling ability due to repeated water-swelling and drying. It also has effects. The urethane resin obtained by the present invention can be used as a water-swellable coating material, a sealant, a caulking material,
Can be used for coating dry sheets, etc. In particular, the urethane resin obtained by the present invention does not lose its water swelling properties even in seawater, hard water, and water containing metal ions such as sodium, calcium, and iron, so it is suitable for marine construction, river closure construction, buildings, etc. It is also extremely useful as a water stop material for filling gaps in root cutting work such as laying water pipes, water stop work in reservoirs, etc. The present invention will be further explained below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Parts in the examples indicate parts by weight. In addition, the swelling ratio in the examples is water absorption amount (g)/weight of water-swellable urethane resin composition before immersion (g) x 100, and the water stop test was conducted as follows. Waterstop test Primer (oxyalkylene ether of bisphenol A and urethane prepolymer of crude MDI; NCO% 4%) inside a steel pipe with an inner diameter of 20 mm.
After drying at room temperature for 30 minutes, a mixture of the urethane prepolymer [A] of the present invention and the polyether polyol [B] of the present invention as a curing agent in a predetermined ratio was coated to a thickness of 2 mm (3
The inner surface was coated by applying two coats of paint and curing at room temperature in the atmosphere. This steel pipe was attached to the bottom of the water tank, the steel pipe outlet was sealed with a rubber stopper, the water was filled in the water tank, and the water tank was left for 24 hours.The rubber stopper at the steel pipe outlet was removed and the presence or absence of water leakage was tested. Examples 1 to 4, Comparative Examples 1 to 2 The following prepolymers and curing agents were used, mixed at the NCO/OH ratio shown in Table 1, poured onto a glass plate, and heated in the atmosphere at room temperature for 24 hours. After time curing, a water-swellable urethane resin molded product with a thickness of 2 mm was obtained. The swelling rate of this water-swellable urethane resin molded product was measured after immersion in tap water and 3% saline solution.
The shape retention after swelling was investigated, and a water stop test was also conducted on this water-swellable urethane resin, and the results are also shown in Table 2. (Prepolymer) ``Polyether glycol with an average molecular weight of 4000 (hereinafter referred to as polyether glycol) obtained by adding a mixture of EO and PO with an EO/PO weight ratio of 80/20 to ethylene glycol, 1000 g and glycerin with EO/PO Polyether triol (hereinafter referred to as polyether triol) 50 with an average molecular weight of 3366 obtained by adding an EO/PO mixture with a PO weight ratio of 70/30
157.4 g (NCO/OH
Ratio: 3.32) was added and reacted at 80℃ for 5 hours to produce NCO.
A urethane prepolymer having a percentage of 4.4% (hereinafter referred to as urethane prepolymer) was obtained. (Curing agent) Polyether glycol (hereinafter referred to as curing agent) containing lead octoate in an amount of 0.5% based on the weight of polyether glycol was used as a curing agent.

[Table] Examples 5, 6, Comparative Example 3 The following prepolymers and curing agents were used.
Mixed at an NCO/OH ratio of 2.5, poured onto a glass plate, and cured in the air at room temperature for 24 hours to a thickness of 2 mm.
A water-swellable urethane resin molded product was obtained. We measured the swelling rate of this water-swellable urethane resin molded product after immersion in tap water and 3% saline solution, examined the shape retention after swelling, and conducted a water stop test on this water-swellable urethane resin. The results are shown in Table-2. (Prepolymer) Γ urethane prepolymer; TDI-80 145 to 1000g of polyether glycol described in Example 1
g (NCO/OH ratio 3.32) and reacted at 80° C. for 5 hours to obtain a urethane prepolymer with an NCO% of 4.3% (hereinafter referred to as urethane prepolymer). Γ urethane prepolymer: 800 g of the polyether glycol described in Example 1 and 200 g of the polyether triol described in Example 1 were mixed.
Add 167g of TDI-80 (NCO/OH ratio 3.32),
The reaction was carried out at 80° C. for 5 hours to obtain a urethane prepolymer having an NCO% of 4.8% (hereinafter referred to as urethane prepolymer). Γ urethane prepolymer; 500 g of the polyether glycol described in Example 1 and 500 g of the polyether triol described in Example 1 were mixed,
Add 200g of TDI-80 (NCO/OH ratio 3.32) to 80
The reaction was carried out at ℃ for 5 hours to obtain a urethane prepolymer having an NCO% of 5.6% (hereinafter referred to as urethane prepolymer). (Curing agent) Γ curing agent The same curing agent as described in Example 1 was used. Γ Curing Agent A mixture of 800 g of the polyether glycol described in Example 1, 200 g of the polyether triol described in Example 1, and 5 g of lead octoate (hereinafter referred to as a curing agent) was used. Γ Curing Agent A mixture of 500 g of the polyether glycol described in Example 1, 500 g of the polyether triol described in Example 1, and 5 g of zinc octoate (hereinafter referred to as a curing agent) was used.

【table】

[Table] Examples 7 and 8, Comparative Examples 4 and 5 100g of the following prepolymer and 83g of the following curing agent
(NCO/OH ratio 2.5), poured onto a glass plate, and cured in the atmosphere at room temperature for 24 hours to obtain a water-swellable urethane resin molded product with a thickness of 2 mm. The swelling rate and shape retention after swelling of this water-swellable urethane resin molded product after immersion in tap water and 3% saline were investigated. Furthermore, a water stop test was conducted on this water-swellable urethane resin, and the results are also presented. −
Shown in 3. (Prepolymer) 1000 g of polyether glycol (hereinafter referred to as polyether glycol) with an average molecular weight of 4000 obtained by adding a mixture of EO and PO at the weight ratio of EO and PO shown in Table 3 to ethylene glycol (hereinafter referred to as polyether glycol) and Example 1
TDI-
80 Add 157.4g (NCO/OH ratio 3.32) and heat at 80℃
A urethane prepolymer with an NCO% of 4.4% was obtained by reacting for a period of time. (Curing agent) Polyether glycol containing 0.5% of the weight of polyether glycol of lead octoate was used as a curing agent component.

[Table] Comparative Examples 6 to 9 The following prepolymers and curing agents were used, mixed at the NCO/OH ratio shown in Table 4, and the same as Examples 1 to 4 and Comparative Examples 1 to 2. I went to The results are shown in Table 4.

【table】

【table】

Claims (1)

[Scope of Claims] 1 Urethane prepolymer [A] having isocyanate groups at the terminals of polyether polyol (a) and organic polyisocyanate (b) and polyether polyol [B] are prepared at an NCO/OH ratio of 2.1 to 4. A method for producing a water-swellable urethane resin, which comprises reacting [A] and [B] in the presence of a catalyst and simultaneously reacting moisture in the atmosphere to cause moisture curing. 2. The method according to claim 1, wherein (a) is an oxyethylene/oxypropylene copolymer polyether polyol. 3. The manufacturing method according to claim 1 or 2, wherein [B] is an oxyethylene/oxypropylene copolymer polyether polyol. 4 The oxyethylene content of (a) is 50 to 90% based on the total weight of oxyethylene and oxypropylene
The manufacturing method according to claim 2 or 3. 5 The oxyethylene content of [B] is 50 to 50% based on the total weight of oxyethylene and oxypropylene
90% of the manufacturing method according to any one of claims 2 to 4. 6 (a) and/or [B] has an average number of functional groups per molecule of 2 to 2.5.
The manufacturing method according to any of paragraph 5.