JPH08311144A - Aqueous dispersion of crosslinked polyurethane resin particle - Google Patents

Abstract

PURPOSE: To obtain an aqueous dispersion of crosslinked polyurethane resin particles which has stable dispersibility in water and shows excellent blocking resistance, when it is used as an ink binder for boiling retorts, by using a polyethyleneimine as a chain extender. CONSTITUTION: (A) A urethane polymer bearing NCO groups on its chain terminals is emulsified or dispersed in water, then (B) allowed to react with a chain extender where a polyethyleneimine (preferably with a number-average molecular weight of 200-2,000) is used as a component B. It is preferred that the component A be self-dispersible, has a 0.5-10wt.% NCO group content, while the component B is used in an amount of 0.2-1.2 equivalent in combination of the primary and the secondary amino groups in its molecule per equivalent of the NCO group in the component A.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous dispersion of crosslinked polyurethane resin particles. More specifically, it is a highly crosslinked fine resin particle having an average particle diameter of 1 micron (μm) or less and has stable water dispersibility. Moreover, this aqueous dispersion is excellent in pigment dispersibility and can be coated. , A continuous film is formed by drying, and the film is tough and has excellent adhesion, water resistance, heat resistance, solvent resistance, etc.
It is useful as a binder for inks, printing agents, fiber treatment agents, adhesives and other coating compositions.

[0002]

In order to obtain an aqueous dispersion of a polyurethane resin, usually, a urethane prepolymer having an isocyanate (NCO) group at its terminal is emulsified or dispersed in water, and then a chain extender such as diamine in the water. The manufacturing method of reacting with is taken. However, the coating obtained by applying the aqueous dispersion of the polyurethane resin thus obtained is extremely softened when heat is applied and causes problems such as blocking, so that it has a narrow range of applications.

Several methods for obtaining an aqueous dispersion of a crosslinked polyurethane have been proposed as methods for improving such drawbacks. For example, in U.S. Pat. No. 4,408,008, water-dispersed isocyanate-terminated linear prepolymers are used to disperse dispersed particles by using a polyamine having a functionality of 2.2 to 6.0 as a chain extender. A manufacturing method for crosslinking the inside is disclosed. However, with this method, the crosslinked structure is not preferable, and the film forming property becomes insufficient when trying to increase the degree of crosslinking, and it is difficult to obtain a film having both flexibility and strength.

Further, JP-A-3-128912 discloses a water-dispersible urethane prepolymer having an isocyanate group as an end group and an average isocyanate functionality of 2.1 to 2.1.
Disclosed is an aqueous dispersion of polyurethane consisting of the reaction product of a polyisocyanate having 4.0 and a chain extender having active hydrogen. However, this is because the polyisocyanate is hydrophobic and is not water-dispersible itself, so that in order to stably disperse it in water, the hydrophilic group of the urethane prepolymer is increased correspondingly or an emulsifier is added. They must be used in combination, and they adversely affect the film performance such as adhesiveness and water resistance, which is unsatisfactory.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned drawbacks of conventional aqueous dispersions of crosslinked polyurethane. That is, it is intended to provide an aqueous dispersion of crosslinked polyurethane having stable water dispersibility, good film forming property, and having a tough film, which is excellent in adhesiveness, water resistance, heat resistance, solvent resistance and the like. It is an issue.

[0006]

The present inventor has completed the present invention as a result of extensive studies to solve the above problems. That is, the present invention provides an aqueous polyurethane resin composition obtained by emulsifying or dispersing a urethane prepolymer having an NCO group at a terminal in water and subsequently reacting the same with a chain extender in the water. It relates to an aqueous dispersion of crosslinked polyurethane resin particles, characterized in that at least a part is polyethyleneimine.

In the present invention, an emulsifier may be used to emulsify or disperse a urethane prepolymer having an NCO group at the end in water, but the urethane prepolymer is self-water dispersible. It is preferable to use one from the standpoint of obtaining a more stable aqueous dispersion and also from the viewpoint of film performance. Here, the above-mentioned self-water-dispersible urethane prepolymer is a self-water-dispersible urethane prepolymer having a hydrophilic group in its molecule, which has the property of forming a stable water dispersion by itself without using an emulsifier. Call out.

It is suitable that the self-water-dispersible urethane prepolymer has an NCO content of 0.5 to 10% by weight and an approximate molecular weight (number average molecular weight) of 800 to 20,000. The self-water-dispersible urethane prepolymer may be dissolved in an organic solvent and used in the form of a diluted solution.

In order to produce a self-water-dispersible urethane prepolymer having such properties, for example, an organic diisocyanate and a polyol component are reacted in a state where an isocyanate group is in excess, and a urethane prepolymer having an isocyanate group at the terminal is obtained. If necessary, a general method for producing a polyurethane in which a chain extender comprising a low molecular weight compound having two or more active hydrogen atoms is used to extend the chain can be applied. Here, in order to impart self-water dispersibility, a compound having a hydrophilic group and two functional groups reactive with isocyanate at the end is used as at least a part of the polyol component and / or the chain extender. To do.

Specific examples of the organic diisocyanate used for producing the above-mentioned urethane prepolymer include ethylene diisocyanate and
1,6-hexamethylene diisocyanate, 2,2,4
Aliphatic diisocyanates such as trimethylhexamethylene diisocyanate and lysine diisocyanate, isophorone diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, methylcyclohexylene diisocyanate, isopropylidene dicyclohexyl-
Examples thereof include alicyclic diisocyanates such as 4,4′-diisocyanate or aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate and tolylene diisocyanate.

Similarly, as the polyol component, those generally used or capable of being used in the production of polyurethane can be applied here. Particularly representative examples are polyester polyols such as dicarboxylic acids (adipic acid, azelaic acid, sebacic acid,
Succinic acid, glutaric acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, etc.) and glycols (ethylene glycol, propylene glycol, 1,4)
-Butanediol, 1,3-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octamethylenediol, neopentyl glycol, bishydroxymethylcyclohexane, bishydroxyethylbenzene, alkyl Obtained by polycondensation with dialkanolamine, etc., such as polyethylene adipate, polybutylene adipate, polymethylpentanediol adipate, polyhexamethylene adipate, polyethylene / propylene adipate;
Polylactone diols such as polycaprolactone diols and polyvalerolactone diols obtained by ring-opening polymerization of lactones, and polyether polyols such as low molecular weight glycols (ethylene glycol, propylene glycol, 1,4-butane diol, etc.) alkylene oxides (carbon number). 2 to 4 alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide) adducts and ring-opening polymers of the alkylene oxides, specifically polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol and two or more thereof. And the like.

Further, only specific examples of the above-mentioned active hydrogen atom-containing low molecular weight compound used as a chain extender are given as examples: ethylene glycol, propylene glycol, 1,4-butanediol, 1, Low molecular weight glycols such as 6-hexanediol and aliphatic diamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethienediamine, 2,2,4-trimethylhexamethylenediamine and isophoronediamine, dicyclohexylmethane-4,4'- Examples include diamines, isopropylidenedicyclohexyl-4,4'-diamines, and alicyclic diamines such as 1,4-diaminocyclohexane.

A functional group having a hydrophilic group for imparting self-water dispersibility and having a terminal reactive with isocyanate is used.
The compound having a hydrophilic group is, for example, a tertiary amino compound as a hydrophilic group, or a carboxyl group, a sulfonic acid group, or an alkali metal salt thereof as an anionic compound. Corresponding diols and diamines having the same, and nonionic diols and diamines having a polyoxyethylene chain are applicable. If only typical examples are given as specific examples, as the cationic tertiary amino compound, for example, N
-Methyldiethanolamine and N-methyldiethylenetriamine. Examples of compounds having an anionic carboxyl group include diaminocarboxylic acids such as lysine, cystine and 3,5-diaminocarboxylic acid,
2,6-dihydroxybenzoic acid, and particularly dihydroxyalkanoic acid such as 2,2-dihydroxypropionic acid and polycaprolactone diol containing a carboxyl group obtained by the reaction of 2,2-dihydroxypropionic acid and ε-caprolactone are sulfonic acid groups. Examples of the polyester diol include a polyester diol in which at least a part of the dibasic acid component is sodium sulfosuccinic acid or sodium sulfoisophthalic acid. And as a thing having a nonionic polyoxyethylene chain,
Examples thereof include polyoxyethylene glycol, polyoxyethyleneoxytetramethylene glycol ether, polyoxyethylene polyoxypropylene glycol ether, polyoxyethylene diaminopropyl ether and the like.

Polyethylene glycol monoether is also suitable for introducing the polyoxyethylene chain, and specific examples thereof include polyoxyethylene monomethyl ether. Then, by introducing the necessary amount of these hydrophilic groups into the molecule of the urethane-based polymer, they are dispersed in water as fine particles, and the required amount is the kind of hydrophilic group or a combination thereof. Depends on.

Particularly preferred as such a hydrophilic group is an acid having an acid value of 5 to 40 based on a carboxyl group and / or a sulfonic acid group or an alkali metal salt thereof and a polyoxyethylene chain of 0 to 20%.
The thing contained is mentioned. As a hydrophilic group, when a nonionic type is used together with an anionic type, a synergistic effect appears, and good water dispersibility is obtained even if the total content of the hydrophilic group is smaller than usual. Therefore, it is possible to minimize the deterioration of the water resistance of the film due to the hydrophilic group.

The above-mentioned urethane prepolymer may be synthesized or used in a solventless system, but a solvent may be used if necessary. Suitable solvents used here are those which are non-reactive with the isocyanate groups and which are miscible with water. Specific examples include acetone, tetrahydrofuran, and
Methyl ethyl ketone, ethyl acetate, dimethylformamide, N-methylpyrrolidone and the like can be mentioned.

In the synthesis of the above urethane prepolymer, a usual urethanization catalyst such as a tertiary amine or a metal compound may be used if desired. Specific examples include triethylamine, N, N-dimethylcyclohexylamine, dibutyltin dilaurate, tin octylate and the like.

According to the present invention, the NCO is added to the end thus obtained.
A urethane prepolymer having a group is emulsified or dispersed in water, and a chain extender containing polyethyleneimine is added thereto, whereby chain elongation and crosslinking occur in the dispersed particles, resulting in a dispersion of crosslinked particles. However, this operation needs to be performed promptly in order to avoid the reaction between the isocyanate group and water. Usually, the reaction between the isocyanate group and water is slow, and the reaction between the isocyanate group and the amino group of polyethyleneimine is extremely fast compared to this.Therefore, adding a chain extender immediately after the dispersion of the prepolymer in water causes problems. The desired cross-linking reaction can be achieved without the need.

The polyethyleneimine used in the present invention is obtained by ring-opening polymerization of ethyleneimine in the presence of an acid catalyst, and the polymer has a chemical structure containing primary, secondary and tertiary amino groups. Has a branch. The molecular weight of polyethyleneimine used in the present invention is 200 to 2000.
It is appropriate to select from the range. When the molecular weight is smaller than this, there is no substantial difference from the case where polyamine is used, and when the molecular weight is larger than 2000, the dispersed particles tend to aggregate at the stage of chain extension, making it difficult to obtain a stable aqueous dispersion. is there. Corresponding commercially available polyethyleneimines include Nippon Shokubai's Epomin SP-003 (molecular weight = about 300), Epomin SP-006 (molecular weight = about 600), Epomin SP-012 (molecular weight = about 120).
0), Epomin SP-018 (molecular weight = about 1800),
Epomin SP-103 (molecular weight = about 250) and Epomin SP-110 (molecular weight = about 1000) can be mentioned.

The amount of polyethyleneimine used in the present invention is such that the equivalent number of the primary and secondary amino groups contained in the molecule of polyethyleneimine is 0.2-1 per equivalent of NCO groups of the urethane prepolymer. It is suitable to use in the range of 0.2. If it is less than this range, the desired degree of crosslinking cannot be obtained, and if it is more than this range, there are adverse effects such as impairing dispersion stability, which is not suitable. Further, as the chain extender, polyethyleneimine may be used, and in some cases, polyamines such as hydrazine, ethylenediamine and diethylenetriamine may be used in combination.

The solvent used in the process of obtaining the aqueous dispersion of the crosslinked polyurethane resin particles of the present invention can be removed if necessary. As a method for removing the solvent, a method using a membrane can be considered, but distillation under normal pressure or reduced pressure may be performed. Further, for example, when the water-dispersible hydrophilic group is an anionic one, an acid is added to the dispersion system to once precipitate the dispersion resin, which is filtered and washed, and then re-immersed in water containing a base. There is also a method of redispersion. In this case, for example, caustic soda may be used as the base for the first water dispersion, and ammonia may be used as the base for the redispersion.

[0022]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, Comparative Examples and Test Examples, but the present invention is not limited thereto. All parts and% in the examples are based on weight.

(Example 1) PLACCEL was placed in a reaction vessel.
212 (manufactured by Daicel Chemical Industries, Ltd., polycaprolactone diol, hydroxyl value 90 mgKOH / g) 60.
9 parts and 32.6 parts of isophorone diisocyanate were charged. When this was heated to 75 ° C. with stirring, heat was generated and the temperature was raised to 110 ° C. Continue to stir at 110 ° C for 1 hour, cool to 80 ° C,
6.5 parts of dimethylolpropionic acid, 0.1 parts of dibutyltin dilaurate and 25 parts of methyl ethyl ketone.
0 part was added and reacted at 80 ° C. for 2 hours. To this, 42 parts of methyl ethyl ketone was added to obtain a solution of urethane prepolymer having an NCO group at the end (solid content 60.0%). The NCO group content at this time is 4.0% in terms of solid content.
Met. This is designated as prepolymer A.

167 parts of prepolymer A (solid content 100
5.0 parts of triethylamine was added, and this was mixed with 344 parts of ion-exchanged water to obtain an O / W type emulsion. Then Epomin SP-003 (polyethyleneimine manufactured by Nippon Shokubai Co., molecular weight about 300, amine value 21 m
g. eq / g, of which primary and secondary amines are about 85%), and a solution of 5.0 parts of ion exchanged water of 45 parts, and
After the addition was completed, the temperature was raised to 60 ° C. and stirring was continued for 30 minutes.
Then, distillation was performed under reduced pressure to remove a part of the solvent and water to obtain an aqueous dispersion of crosslinked polyurethane resin particles.

(Example 2) Epomin S in Example 1
Epomin SP-006 instead of 5.0 parts of P-003
(Polyethyleneimine manufactured by Nippon Shokubai Co., molecular weight about 600,
Amine value 20 mg. An aqueous dispersion of crosslinked polyurethane resin particles was obtained by the same method except that 5.0 parts of eq / g, and primary and secondary amines were about 83%).

(Example 3) Epomin S in Example 1
Epomin SP-012 instead of 5.0 parts of P-003
(Polyethyleneimine manufactured by Nippon Shokubai Co., molecular weight about 120
0, amine value 19 mg. An aqueous dispersion of crosslinked polyurethane resin particles was obtained by the same method except that 5.0 parts of eq / g, and primary and secondary amines were about 80%).

(Example 4) Epomin S in Example 1
Epomin SP-018 instead of 5.0 parts of P-003
(Polyethyleneimine manufactured by Nippon Shokubai Co., molecular weight about 180
0, amine value 19 mg. An aqueous dispersion of crosslinked polyurethane resin particles was obtained by the same method except that 5.0 parts of eq / g, and primary and secondary amines were about 80%).

(Example 5) Epomin S in Example 1
Epomin SP-012 instead of 5.0 parts of P-003
(Polyethyleneimine manufactured by Nippon Shokubai Co., molecular weight about 120
0, amine value 19 mg. An aqueous dispersion of crosslinked polyurethane resin particles was obtained by the same method except that 1.5 parts of eq / g, where primary and secondary amines were about 80%) and 2.0 parts of diethylenetriamine were used.

Comparative Example 1 Epomin S in Example 1
Epomin SP-200 instead of 5.0 parts of P-003
(Polyethyleneimine manufactured by Nippon Shokubai Co., molecular weight about 1000
0, amine value 18 mg. When 5.0 parts of eq / g, of which primary and secondary amines were about 70%) was used, aggregation of the resin occurred and an aqueous dispersion of the crosslinked polyurethane resin particles could not be obtained.

(Comparative Example 2) Epomin S in Example 1
An aqueous dispersion of crosslinked polyurethane resin particles was obtained by the same method except that 3.0 parts of diethylenetriamine was used instead of 5.0 parts of P-003.

Example 6 PolyTHF was placed in a reaction vessel.
1000 (manufactured by BSF Japan Ltd., polytetramethylene glycol, hydroxyl value 112 mgKOH /
64.5 parts of g), 8.4 parts of hexamethylene diisocyanate and 22.3 of isophorone diisocyanate.
The department was set up. When this was heated to 75 ° C. with stirring, heat was generated and the temperature was raised to 110 ° C. After continuing stirring at 110 ° C. for 1 hour, the mixture was cooled to 80 ° C., and 4.8 parts of dimethylolpropionic acid, 0.1 part of dibutyltin dilaurate and 2 parts of methyl ethyl ketone were added.
5.0 parts was added and reacted at 80 ° C. for 2 hours. here,
42 parts of methyl ethyl ketone was added, and a solution of urethane prepolymer having an NCO group at the end (solid content 60.0
%) Was obtained. At this time, the NCO group content was 40% in terms of solid content. This is designated as Prepolymer B.

167 parts of prepolymer B (solid content 100
1.5 parts of caustic soda and Epomine SP-012 (polyethyleneimine manufactured by Nippon Shokubai Co., molecular weight about 1200, amine value 19 mg.eq / g, while stirring).
An aqueous solution containing 5.0 parts of primary and secondary amines (about 80%) and 334 parts of ion-exchanged water was added all at once. After the addition was completed, the temperature was raised to 60 ° C. and stirring was continued for 30 minutes. Then, this was gradually added to dilute hydrochloric acid to precipitate the resin. The precipitated resin was filtered with a centrifuge, washed with water and dehydrated to obtain a solid resin having a water content of 52%. 2 here
When 2.5 parts of 5% ammonia water and 79 parts of ion-exchanged water were added and stirred, the solid resin was redispersed, and an aqueous dispersion of crosslinked urethane resin particles containing no solvent was obtained.

(Measurement of Characteristic Value) Nonvolatile matter, viscosity, pH, average particle diameter and gel fraction of each sample of Examples 1 to 6 and Comparative Example 2 were measured. The results are shown in Table 1. Measurement Method (1) Nonvolatile Content (%) About 1 g of a sample was flatly spread on a Petri dish and dried from 105 ° C. for 1 hour to obtain the weight loss. (2) Viscosity (cps) The sample was adjusted to 25 ° C. and measured with a Brookfield viscometer. (3) pH The sample was adjusted to 25 ° C. and measured with a pH meter M-13 manufactured by Horiba Ltd. (4) Average particle size Measured with a laser particle size analysis system PAR-III manufactured by Otsuka Electronics Co., Ltd. (5) Gel Fraction A 120 mesh stainless wire mesh was cut into a size of 5.5 cm × 9.0 cm, and the weight (W ₁ )
Was measured. The sample was dipped in each sample diluted with water so that the nonvolatile content was 30%, taken out, put in a dryer at 50 ° C. for 2 hours to be dried, and then the weight (W ₂ ) was measured. . This was immersed in methyl ethyl ketone for 24 hours, then taken out, put in a dryer at 50 ° C. for 30 minutes and taken out, and the weight (W ₃ ) was measured. The gel fraction was calculated by the following formula. Gel fraction (%) = {(W ₃ −W ₁ ) / (W ₂ −
W ₁ )} × 100

[0034]

[Table 1]

(Application example to water-based ink) 57 parts of each cross-linked urethane resin aqueous dispersion listed in Table 1, 30 parts of titanium oxide pigment, 10 parts of isopropyl alcohol and 3 parts of ion-exchanged water were respectively applied with a paint conditioner. After kneading, white printing ink was prepared. This white printing ink was printed on the treated surface of a single-sided treated polyester film having a thickness of 12 μm by a simple gravure printing machine equipped with a gravure plate having a plate depth of 30 μm and dried through a dryer at 70 ° C. to obtain a printed film.

The following tests were carried out on the obtained printed film. (1) Blocking resistance test Overlapping printing surfaces, temperature 60 ℃, load 500g / cm
^2. After pressing for 3 hours at a humidity of 75%, the blocking state of the sample surface was observed. The evaluation criteria were as follows.

A: Not blocked B: Slightly blocked C: Blocked

(2) Lamination test As an adhesive, 9 parts of Dick Dry Lx-901 (a main agent manufactured by Dainippon Ink and Chemicals, Inc.), Dick Dry K
Prepare a solution of 1 part of W75 (hardening agent) and 7.5 parts of ethyl acetate, and use drawdown rod # 12 to prepare a solution of 15 μm.
m After applying to the untreated surface of aluminum foil and evaporating the solvent, a linear low-density polyethylene film (thickness 60μ
m, hereinafter abbreviated as LLDPE), and 80 kg / cm ²
Lamination was performed using a pressure roll of pressure. The same adhesive as above was applied to the printed surface of the printed material in the same manner using the draw down rod # 12, the solvent was volatilized, and then the aluminum surface of the aluminum / LLDPE laminate was overlaid with a pressure roll. Lamination was performed.

The laminate thus obtained was aged in a constant temperature bath at 50 ° C. for 72 hours, and then 15
The tape was cut into a tape having a width of mm and Tensilon RTM-25 manufactured by Orientec Co., Ltd. was used, and the peel strength of the T-type peel of the ink layer at a speed of 300 mm / min (unit: g /
15 mm width) was measured (normal peel strength). In addition, a bag of 12 cm x 12 cm was prepared from the laminate, and the bag filled with water was boiled by immersing it in boiling water for 30 minutes and placed in a retort kettle with pressurized steam at 135 ° C for 40 minutes.
After performing retort treatment for 1 minute, immediately after observing the state change of the laminated film (whitening, blister and delamination), the peel strength of the laminate was measured in the same manner as above (peeling after boil and after retort). Strength).

The evaluation criteria of the state change after the boil and retort treatments were as follows. A: No change B: Slight change C: Change These evaluation results are shown in Table 2.

[0041]

[Table 2]

[0042]

The aqueous dispersion of crosslinked polyurethane resin particles of the present invention is highly crosslinked fine resin particles having an average particle size of 1 micron (μm) or less, and has stable water dispersibility, Excellent blocking resistance, adhesion, even when used as an ink binder for boil and retort
An ink film showing water resistance, heat resistance, etc. can be obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09J 175/04 JFA C09J 175/04 JFA

Claims (5)

[Claims] 1. An aqueous polyurethane resin composition obtained by emulsifying or dispersing a urethane prepolymer having an NCO group at a terminal in water, and subsequently reacting the same with a chain extender in the water, wherein at least the chain extender is used. An aqueous dispersion of crosslinked polyurethane resin particles, characterized in that part is polyethyleneimine. 2. The aqueous dispersion of crosslinked polyurethane resin particles according to claim 1, wherein the urethane prepolymer having an NCO group at the end is self-water dispersible. 3. The aqueous dispersion of crosslinked polyurethane resin particles according to claim 1, wherein the urethane prepolymer having an NCO group at the terminal has an NCO content of 0.5 to 10% by weight. 4. The number of equivalents of the primary and secondary amino groups contained in the molecule of polyethyleneimine is 0.2 to 1.2 per equivalent of NCO groups of the urethane prepolymer.
The aqueous dispersion of crosslinked polyurethane resin particles according to claim 1, which is used in the range of 5. The number average molecular weight of polyethyleneimine is 2
The aqueous dispersion of crosslinked polyurethane resin particles according to claim 1, which is selected from the range of 00 to 2000.