JPH0749460B2 - Undiluted solution for manufacturing water-absorbing urethane film and film manufacturing method - Google Patents

Description

The present invention relates to a stock solution for producing a water-absorbing urethane film and a method for producing the water-absorbing urethane film.

[Prior Art] Conventionally, as a water absorbent film, there are a water absorbent film having a water absorption rate of several% such as a nylon film, and a film made by dispersing a water absorbent resin in a nonwoven fabric.

[Problems to be Solved by the Invention] However, nylon films and the like have a low water absorption rate and cannot be applied to applications requiring a high water absorption rate. A product obtained by dispersing a water-absorbent resin in a non-woven fabric cannot withstand long-term use because the water-absorbent resin falls off.

[Means for Solving the Problems] The present inventors intend to provide a water-absorbent film that absorbs 10 to 300% of its own weight of water, can reversibly repeat water absorption and discharge, and can withstand long-term use. The present invention has been achieved as a result of studying a stock solution for producing a water-absorbing urethane film capable of producing the same and a production method thereof. That is, the present invention is as follows.

20-80% of the isocyanate groups in the terminal isocyanate group-containing prepolymer from the aliphatic and / or alicyclic polyisocyanate (A) and the polyoxyalkylene ethers (B) having at least one part having an oxyethylene unit A water-absorbing urethane having a water-absorbing capacity of 10 to 300% of its own weight, which is a stock solution of (F) blocked with an isocyanate blocking agent (D), a chain extender (C), and optionally a solvent. Undiluted solution for film production.

A method for producing a water-absorbing urethane film, which comprises casting the stock solution to a thickness of 500 μm or less, and continuously thermosetting the casting.

In the present invention, examples of the aliphatic and / or alicyclic polyisocyanate (A) include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethylhexane diisocyanate, lysine diisocyanate, 2 , 6-Diisocyanate methyl caproate, bis (2-isocyanate ethyl) fumarate, bis (2-isocyanate ethyl) carbonate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, cyclohexylene diisocyanate, methyl cyclohexylene diisocyanate, bis (2- Isocyanatoethyl) 4-cyclohexene-1,
Examples thereof include 2-dicarboxylate and / or modified products thereof (carbodiimide group, uretdione group, uretoimine group, urea group, buret group and / or isocyanurate group-containing modified product).

When an aromatic polyisoianate is used instead of (A), the chemical resistance and weather resistance are extremely poor, and it can be used only for practically limited applications.

Examples of the polyoxyalkylene ethers (B) having at least one part having an oxyethylene unit include low molecular weight polyols (ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, cyclohexylene glycol, N-methyldiethanolamine, etc. Bifunctional polyol, glycerin,
Trifunctional or more functional polyols such as trimethylolpropane, triethanolamine, pentaerythritol, sorbitol, and sucrose); Bisphenols (bisphenol A, bisphenol S, etc.); Amines (amino alcohols such as monoethanolamine; aliphatic polyamines such as Ethylenediamine,
Diethylenetriamine; cycloaliphatic polyamines such as isophoronediamine; heterocyclic polyamines such as aminoethylpiperazine) and ethylene oxide (EO) or EO and other alkylene oxides [alkylene oxides having 3 to 4 carbon atoms, such as propylene oxide (PO ), Butylene oxide].

Of these, preferred are EO and PO adducts (random and / or block adducts).

The chain extender (C) is similar to the low molecular weight polyols described in (B), and / or low molecular weight polyamines (for example, isophoronediamine, dicyclohexylmethanediamine, tolylenediamine, diethyltolylenediamine, Dimethylthio-tolylenediamine, diphenylmethanediamine, 4,4'-diamino-3,3-dichlorodiphenylmethane and the like).

In the stock solution for producing the film of the present invention, if necessary, a catalyst (dibutyltin dilaurate, zinc octylate, lead octylate, stannas octoate, etc.), filler (talc, bentonite, calcium carbonate, lithopone, silica, mica, etc.) ), A colorant (titanium white, red iron oxide, carbon black, chrome green, etc.), an ultraviolet absorber, an antioxidant, an anti-sagging agent, a plasticizer and the like can be added.

The stock solution of the present invention comprises 20 to 80 isocyanate groups in the prepolymer containing terminal isocyanate groups from (A) and (B).
% Is blocked with an isocyanate blocking agent (D) (F), a chain extender (C), and optionally a solvent. The film is produced using this solution with a thickness of 500 μm. It is cast and heat-cured as follows.

Specific examples of the isocyanate blocking agent (D) used in the stock solution of the present invention include lactams (α-pyrrolidone, γ-butyrolactam, δ-valerolactam, ε-).
Caprolactam, etc.), phenols (phenol, cresol, etc.), oximes (dimethyl ketoxime,
Methyl ethyl ketoxime, diethyl ketoxime, methyl isobutyl ketoxime, etc.), carboxylic acid esters (dimethyl malonate, diethyl malonate, etc.), alcohols (methanol, ethanol, n-butanol, etc.), hydroxyl group-containing ethers (methyl cellosolve, Butyl cellosolve, etc.), hydroxyl group-containing ester (ethyl lactate, amyl lactate, etc.), mercaptans (butyl mercaptan, hexyl mercaptan, etc.), acid amides (acetanilide, acrylic amide, dimer acid amide, etc.), imidazoles (imidazole, 2-ethyl) Imidazole), acid imides (succinimide, phthalimide, etc.) and the like.

As an example of the method for producing a terminal isocyanate group-containing prepolymer from (A) and (B), the molar ratio (B / A) of the isocyanate group of (A) to the active hydrogen of (B) is usually 1.8 to
It can be produced by mixing 4.0, preferably 1.8 to 3.5, and optionally a solvent, and reacting by a conventional method (70 to 140 ° C.) [also produced end NCO group prepolymer (E) Say]. If the molar ratio (B / A) of the isocyanate group to active hydrogen is less than 1.8, the viscosity becomes too high, which causes difficulty during casting of the film production, resulting in poor thickness accuracy. On the other hand, when it exceeds 4.0, the curing time becomes too long during the heat curing of film production.

Solvents that can be added as necessary include toluene, xylene, ethyl acetate, butyl acetate, etc., and the amount thereof is 0 to 80%, preferably 30 to 70% based on the total resin weight.
%. The solvent may be added at any time before the casting step.

Next, the terminal NCO group prepolymer (E) is added with an amount of (D) that normally blocks 20 to 80%, preferably 40 to 60% of the isocyanate groups of (E), and then the conventional method (50 to 120) is used. To produce a mixture [hereinafter also referred to as (F)]. When the amount of (D) is less than 20% of the isocyanate groups of (E), the stock stability of the stock solution of the present invention after addition of (C) is deteriorated. If it exceeds 80%, film casting,
The film is less likely to be repelled during heat curing and requires a long time for heat curing.

Next, (C) and optionally a solvent, a catalyst,
The stock solution of the present invention includes other additives.
The amount of (C) is such that the number of moles of the active hydrogen of (C) is usually 0.7 to 1.1, preferably 0.85 to about the total number of moles of the isocyanate residue and the blocked isocyanate group of (F).
Add 0.95. The mixture of (F) and (C) is (D)
It is preferable to carry out the reaction at a temperature at which the compound does not dissociate from the isocyanate until the isocyanate content becomes 0%.

The undiluted solution of the present invention is cast to about 5 to 500 μ, and usually 70 to 180 ° C.
The film is produced by heat curing for 2 to 30 minutes, preferably 100 to 140 ° C. for 5 to 15 minutes.

The film production from the stock solution of the present invention needs to be continuously carried out from casting of the stock solution to thermosetting, but other manufacturing steps may be carried out continuously or independently.

In the production method of the present invention, the casting of the undiluted solution during continuous casting and thermosetting may be performed on any of release paper, plastic separator or metal belt. Further, a film from the stock solution of the present invention may be prepared on different kinds of films and / or sheets to form a composite film or a composite sheet.

As an apparatus for producing a film from the stock solution of the present invention,
Any apparatus can be used as long as it can uniformly cast the stock solution to a size of 5 to 500 μm and can be heated to a temperature of 70 to 180 ° C.

[Examples] Hereinafter, the present invention will be further described with reference to Examples, but the present invention is not limited thereto.

Example 1 Polyether glycol having an average molecular weight of 2000 obtained by adding a mixture of EO and PO at an EO / PO weight ratio of 60/40 to bisphenol A, and a prepolymer having a NCO% of 3.5% from dicyclohexylmethane diisocyanate, After reacting an amount of ε-caprolactam that blocks 60% of the isocyanate groups of the prepolymer, NC of the prepolymer before blocking
A film stock solution (hereinafter referred to as a film stock solution) was prepared by adding 1,4-butanediol having a hydroxyl group molar ratio of 0.9 to O groups and 0.5% lead octylate based on the total resin weight.

Next, the film stock solution was cast on a polyester separator and then heat-cured at 150 ° C. for 14 minutes to obtain a film of the present invention having a water absorption of 180% and a thickness of 150 μm.

Example 2 A mixed solution of 400 g of talc in a weight ratio of 1000 g of the stock solution of Example 1 was cast on a polyester separator and heat-cured at 150 ° C. for 15 minutes to give a water absorption of 135%.
Then, a film of the present invention having a thickness of 400 μ was obtained.

Example 3 Propylene glycol obtained by adding a mixture of EO and PO in an EO / PO weight ratio of 50/50 was obtained by adding 1000 g of polyether glycol having an average molecular weight of 4000 and PO to glycerin.
After reacting 1000 g of polyether triol having an average molecular weight of 3000 and a prepolymer having an NCO% of 4.4% from isophorone diisocyanate, an amount of methyl ethyl ketone at which 50% of the isocyanate groups of the prepolymer are blocked is reacted,
Diethyl tolylenediamine with an amino group molar ratio of 0.88 relative to the isocyanate groups of the prepolymer before block, 0.5% lead octylate with respect to the total resin amount, and toluene with a solid content concentration of 60% are added, 0% NCO% at 35 ° C
It was made to react until it became a film stock solution.

This film stock solution was cast on a silicone release paper and then heat cured at 120 ° C for 10 minutes to obtain a water absorption of 105% and a thickness of 20μ.
A film of the present invention was obtained.

Example 3 100 g of a polyether glycol having an average molecular weight of 4000 and 100 g of polyoxytetramethylene glycol having an average molecular weight of 1000, obtained by adding a mixture of EO and PO having an EO / PO weight ratio of 50/50 to propylene glycol, After reacting a prepolymer with a NCO% of 3.0% from phorone diisocyanate with an amount of methyl ethyl ketone that blocks 55% of the isocyanate groups of the prepolymer, the molar ratio of amino groups to 0.9 before the blocking is 90%. Add dicyclohexyldiamine and xylene in an amount of
The reaction was carried out until O% became 0 to prepare a film stock solution.

The film stock solution was cast on a polyester separator and then heat-cured at 150 ° C. for 15 minutes to obtain a film of the present invention having a water absorption of 85% and a thickness of 50 μm.

Example 4 NCO from propylene glycol, EO / PO EO / PO weight ratio of 50/50, polyether glycol having an average molecular weight of 2000, and Duranate D-101 [produced by Asahi Kasei Corporation, hexamethylene diisocyanate modified product] After reacting 10.5% of the prepolymer with an amount of α-pyrrolidone which blocks 55% of the isocyanate groups of the prepolymer, the molar ratio of amino groups to isocyanate groups of the prepolymer before blocking is 0.9. Hexamethylenediamine in an amount of 50% and butyl acetate with a solid concentration of 50% are added, and NC is performed at 40 ° C.
The reaction was carried out until O% became 0 to obtain a film stock solution.

The film stock solution was cast on a polyester separator and then cured at 150 ° C. for 20 minutes to obtain a film of the present invention having a water absorption of 65% and a thickness of 80 μm.

[Effect of the invention] The film from the stock solution of the present invention has a large water absorption rate (absorbs 10 to 300% of its own weight of water), can reversibly repeat water absorption and discharge, and has a long-term water absorption capacity. To maintain.

According to the production method of the present invention, a high-quality water-absorbent urethane film can be easily produced at low cost.

As the application of the film from the stock solution of the present invention, a dew condensation preventing material
There are freshness-retaining agents for vegetables and fruits, dehydrating agents, humidity-retaining agents, fragrance impregnating and timely dispersing agents, and medical external medicine impregnating agents.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A 64-34402 (JP, A) JP-A 61-130324 (JP, A) JP-A 60-76525 (JP, A) JP-A 62- 57457 (JP, A) JP 62-167314 (JP, A) JP 64-9213 (JP, A) Special table 63-500590 (JP, A)

Claims (3)

[Claims] 1. An isocyanate group in a terminal isocyanate group-containing prepolymer comprising an aliphatic and / or alicyclic polyisocyanate (A) and a polyoxyalkylene ether (B) having at least one part having an oxyethylene unit. (F) with 20-80% of which is blocked by an isocyanate blocking agent (D), and a chain extender (C)
And a solvent if necessary
A stock solution for the production of water-absorbing urethane films with a water absorption capacity of 300%. 2. The molar ratio (B / A) of the isocyanate group of (A) to the active hydrogen of (B) is 1.8 to 4.0, and
The stock solution according to claim 1, wherein the number of moles of active hydrogen of the chain extender (C) is 0.7 to 1.1 times the total number of moles of the isocyanate residue and the blocked isocyanate group of (F). 3. The stock solution according to claim 1 or 2 having a thickness of 500 μm.
A method for producing a water-absorbing urethane film, which comprises the following casting and thermosetting continuously with this casting.