KR101124471B1 - Synthesis and composition of solvent-free waterborne polyurethane emulsion - Google Patents

Abstract

A process for producing a solvent-free aqueous polyurethane emulsion of the present invention and a solvent-free aqueous polyurethane emulsion prepared by the method is a mixture having a hydroxyl group at the end of the hydrophilic group using a hydrophilic polyurethane diol oligomer and monomeric diol together with a polyol. The solvent-free aqueous polyurethane emulsion produced by producing a polyurethane prepolymer having an isocyanate group at the molecular end thereof using a minimally introduced ionic group and an aromatic aliphatic diisocyanate system that does not generate side reactions at a high temperature is produced by It has excellent degradability and good adhesion and water dispersion stability, so it can be applied to various materials such as rubber, leather, plastic, and shoe parts.In addition, it does not require an organic solvent to remove the solvent. Work processes are shortened, It is less harmful to the human body of the worker, it is an advantage that is environmentally friendly.

Hydrolyzed, Polyurethane, Aqueous Adhesive, Shoe, Emulsion, Water Dispersible, Solvent-Free

Description

A method for preparing a solvent-free aqueous polyurethane emulsion and a solvent-free aqueous polyurethane emulsion prepared by the method {Synthesis and composition of solvent-free waterborne polyurethane emulsion}

The present invention uses an aromatic aliphatic diisocyanate system that uses a minimum of an ionic group to introduce a hydrophilic group, and does not generate side reactions at high temperature, and has excellent hydrolysis resistance and good adhesion and water dispersion stability. Since no solvent is used to remove the solvent, the process is shortened, the work process is shortened, it is less harmful to the human body, and an environmentally friendly, solvent-free, water-soluble polyurethane emulsion production method and hydrolysis resistance produced by the method This is an excellent solvent-free aqueous polyurethane emulsion.

In general, adhesives prepared by synthesizing polyurethanes are widely used in industrial fields, and such initial polyurethane synthesis is performed by evaporating and curing an organic solvent in order to suppress nonuniformity and side reactions of the mixture during the reaction. lost.

However, as the use of such volatile organic solvents is regulated due to air pollution and human health, studies on the replacement of organic solvents or introduction of solvents are being actively conducted. As an alternative, an aqueous polyurethane emulsion can be divided into a self-emulsifying method in which a certain hydrophilic group is introduced into a molecule and a forced emulsifying method using a high mechanical shear force in the presence of an emulsifier. [US 4,066,591, US 4,417,679, US 4,857,565, US 5,552,496, Japanese Patent Laid-Open No. 4-328187, Japanese Patent Laid-Open No. 5-43642, Japanese Patent Laid-Open No. 63-69882, Japanese Patent Laid-Open No. 9-157625, Japan Patent Publication No. 39-5989, Japan Patent Publication No. 45-109575]

Among them, the forced emulsification method is suitable for low molecular weight polymers and has a high viscosity, which causes a lot of losses, and there is a problem of post-treatment of emulsifiers and deterioration of physical properties. Thus, self-emulsification is generally used to prepare an aqueous polyurethane emulsion.

In addition, in order to hydrophobize the hydrophobic polyurethane, an ionic group in the molecular chain is chemically bonded to a prepolymer terminated with an isocyanate or chemically through a chain extender used for chain extension of the prepolymer. Mainly used anionic groups include carboxyl groups and sulfonated groups, which are formed by neutralization of ionic groups. In this case, the neutralized ionic group is hydrophilic to provide an internal dispersing point, and the resulting carboxyl group and sulfonated group are inherently hydrophilic, a major cause of hydrolysis resistance, and at high ion concentrations, as a result of ionic interactions between the chains. The result is that the bond strength of the polymer is increased, but the content of the ionic group consequently influences not only the dispersion stability but also the physical properties such as adhesive strength, hydrolysis resistance, and flexibility.

Conventional studies on the content of ionic groups have shown that the size of particles after emulsification decreases with increasing content. Particle size is an important factor affecting the mechanical properties of aqueous polyurethane emulsion films. The smaller is, the more transparent the appearance of the film of the prepared aqueous polyurethane emulsion, and has the soft characteristics. And while the elongation increases, the tensile strength has a characteristic that affects the mechanical properties such as falling.

In order to emulsify the water-based polyurethane emulsion in water, an appropriate amount of ionic groups should be used. Until now, the amount of ionic groups used for synthesis in consideration of water dispersion stability is about 2.5 wt% or more compared to solids. And weak resistance to hydrolysis resistance. In order to solve this problem, various methods have been examined. Korean Patent Publication No. 1998-066934 discloses that water-resistant polyurethane adhesives have been manufactured by using an aromatic polyisocyanate compound to improve water resistance. By using it, there is a problem that discoloration occurs over time after adhesion and a problem of removing the solvent after completion of the reaction by using an excess solvent during the reaction. Also, in order to improve hydrolysis resistance, an aqueous polyurethane emulsion is prepared by using a polyether polyol, but the hydrolysis resistance is slightly improved, but the cohesive force of the prepared aqueous polyurethane emulsion is poor, and thus the initial and state adhesive strength, heat adhesive strength, etc. It shows a problem of poor adhesive properties. And research on solvent-free aqueous polyurethane emulsion has been actively conducted both domestically and internationally. However, it is still poorly hydrolyzed and has limited limitations in application, and also uses organic solvents for viscosity control during the reaction. There is a situation.

Therefore, in order to solve the above problems, the present invention uses a hydrophilic polyurethane diol oligomer and a monomer diol with a polyol in a mixture having a hydroxyl group at the end, using a minimum of the ionic group to introduce a hydrophilic group, at a high temperature By using an aromatic aliphatic diisocyanate system that does not generate side reactions, the hydrolysis resistance is very good, the adhesion and water dispersion stability are not only good, and the organic solvent is not used so that the solvent removal step is not necessary. It is an object of the present invention to provide a method for preparing a solvent-free aqueous polyurethane emulsion which is shortened, is less harmful to a human body, and is environmentally friendly, and a solvent-free aqueous polyurethane emulsion prepared by the method.

The present invention for achieving the above object is to prepare a polyurethane prepolymer having an isocyanate group at the molecular end by reacting the polyol, monomer diol, polyurethane diol oligomer and ionic groups with diisocyanate as a mixture having a hydroxyl group at the end ( S1);

Neutralizing the polyurethane prepolymer prepared in the step (S1) with a neutralizing agent to prepare a self-emulsifying prepolymer (S2);

(S3) extending the chain by adding water to the self-emulsifying prepolymer prepared in the step (S2), and emulsifying by adding a chain extender;

A method for producing a solvent-free aqueous polyurethane emulsion, characterized in that the production including a.

And as a mixture having a hydroxyl group at the end of the (S1) step 0.46 ~ 0.59 mol polyol, 0.12 ~ 0.16 mol monomer diol, 0.12 ~ 0.16 mol polyurethane diol oligomer and 0.17 ~ 0.22 mol ionic group, and having a hydroxyl group at the terminal 1.15 to 1.5 mol of diisocyanates are used per 1 mol of the mixture,

The neutralizer of step (S2) is used in a ratio of 1: 1 with the amount of the ionic group,

The water of step (S3) is used so that the solid content of the prepared solvent-free aqueous polyurethane emulsion is 25 to 60% by weight, and the chain extender is used at 0.05 to 0.5 mole based on 1 mole of the mixture having a hydroxyl group at the terminal. Preferably,

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The polyurethane diol oligomer used in the step (S1) is a compound having a hydroxyl group at the terminal, 0.3 to 0.7 parts by weight of 1,6-hexanediol, 0.3 to 0.7 parts by weight of 1-methylamino-2,3-propanediol, It is manufactured including 0.5-1.5 weight part of aliphatic isocyanate, and it is preferable that number average molecular weights are 450-550.

A method for producing a solvent-free aqueous polyurethane emulsion of the present invention and a solvent-free aqueous polyurethane emulsion prepared by this method is a mixture having a hydroxyl group at the end of the hydrophilic polyurethane with a polyol By preparing a polyurethane prepolymer having an isocyanate group at the molecular end of the molecule using a diol oligomer and a monomeric diol using a minimum of an ionic group which introduces a hydrophilic group and no side reaction occurs at high temperatures Solvent-free, water-based polyurethane emulsion has excellent hydrolysis resistance and good adhesion and water dispersion stability, so it can be applied to various materials such as rubber, leather, plastic, and shoe parts, and also does not use organic solvents. Do not remove solvent Since it is not necessary, the work process is shortened, there is little harm to the human body of the operator, it is an advantage that it is environmentally friendly.

The present invention for achieving the above effect relates to a method for preparing a solvent-free aqueous polyurethane emulsion composition and to a solvent-free aqueous polyurethane emulsion composition prepared by the method, only the parts necessary for understanding the present invention are described. It should be noted that descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

Hereinafter, the technical configuration of the solvent-free aqueous polyurethane emulsion composition of the present invention and the solvent-free aqueous polyurethane emulsion composition prepared by the method will be described in detail.

The present invention comprises the steps of preparing a polyurethane prepolymer having an isocyanate group at the molecular end by reacting a polyol, monomer diol, polyurethane diol oligomer and ionic groups with diisocyanate as a mixture having a hydroxyl group at the end (S1);

Neutralizing the polyurethane prepolymer prepared in the step (S1) with a neutralizing agent to prepare a self-emulsifying prepolymer (S2);

(S3) extending the chain by adding water to the self-emulsifying prepolymer prepared in the step (S2), and emulsifying by adding a chain extender;

It relates to a method for producing a solvent-free aqueous polyurethane emulsion comprising a.

And the method for producing a solvent-free aqueous polyurethane emulsion of the present invention is a mixture having a hydroxyl group at the end of the step (S1) 0.46 ~ 0.59 mol polyol, 0.12 ~ 0.16 mol monomer diol, 0.12 ~ 0.16 mol polyurethane diol oligomer and ions 1.15-1.5 mol of diisocyanates are used with respect to 0.17-0.22 mol of a genus group, and 1 mol of mixtures which have a hydroxyl group at the said terminal,

The neutralizing agent of the step (S2) is used in a ratio of 1: 1 with the amount of the ionic group,

The water of step (S3) is used so that the solid content of the prepared solvent-free aqueous polyurethane emulsion is 25 to 60% by weight, and the chain extender is used at 0.05 to 0.5 mole based on 1 mole of the mixture having a hydroxyl group at the terminal. It is characterized by.

Polyol constituting the mixture having a hydroxyl group at the terminal in the step (S1) of the present invention is a compound having at least two hydroxyl groups, it is used to improve the cohesive force of the adhesive, it is preferable to use 0.46 ~ 0.59 mol. When the amount of use is less than 0.46 mole, the cohesive force of the adhesive is poor, and when the amount is more than 0.59 mole, the hydrolysis resistance is poor.

In this case, the polyol may be used by using a polyester polyol alone or a mixture of polyester polyol and polycaprolactone diol at room temperature, It is preferable that the said polyol uses 0.3 mol or more of polyester polyols in 0.46-0.59 mol. When the amount of the polyester polyol is less than 0.3 mol, the stability of the emulsion is lowered and the adhesive property is lowered such that the adhesive strength is lowered.

The polyester-based polyol may be selected from one or more of polyethylene adipate, polybutylene adipate and polyethylene butylene adipate, and it is preferable to use polybutylene adipate.

The number average molecular weight of the polyester polyol and the polycaprolactone diol used as the polyol may be 2,000 or more, preferably 2,000 to 3,000. If the number average molecular weight is less than 2,000, there is a problem that the adhesive properties of the adhesive is inferior, if the number average molecular weight is more than 3,000, the initial tack (low) initial tack is low, resulting in poor crimping at the time of adhesion, the initial adhesive force is insufficient, rather Performance may be degraded.

In the step (S1) of the present invention, the monomer diol constituting the mixture having a hydroxyl group at the terminal is used to minimize the stability of the emulsion and the content of the ionic group, and it is preferable to use 0.12 to 0.16 moles. If the amount of use is less than 0.12 moles, the water dispersion stability of the emulsion is inferior, and if the amount is more than 0.16 moles of hydrolysis resistance is excellent, but other adhesive properties are deteriorated.

The monomer diol may be used by selecting one or more of ethylene glycol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol, and it is preferable to use 1,6-hexanediol.

Polyurethane diol oligomer constituting the mixture having a hydroxyl group at the end in the step (S1) of the present invention is used to minimize the stability of the emulsion and the content of the ionic group, It is preferable to use 0.12-0.16 mol. If the amount of use is less than 0.12 moles, the water dispersion stability is lowered. If the amount is more than 0.16 moles, the hydrolysis resistance is excellent but other adhesive properties are degraded.

And the polyurethane diol oligomer is a compound having a hydroxyl group at the terminal, 0.3 to 0.7 parts by weight of 1,6-hexanediol, 0.3 to 0.7 parts by weight of 1-methylamino-2,3-propanediol, 0.5 to 1.5 parts by weight of aliphatic isocyanate It is manufactured including the part and it is preferable that number average molecular weights are 450-550. It is preferable to make reaction temperature at this time react for 60 to 70 degreeC for 1.5 to 2.5 hours.

As the aliphatic isocyanate, one or more selected from 1,6-hexane diisocyanate (HDI), isophorone diisocyanate (IPDI), methylene bis (p-cyclohexyl isocyanate) (H ₁₂ MDI) and the like can be used. Can be.

In addition, the synthesis of the polyurethane diol oligomer briefly described as follows.

First, 0.3 to 0.7 parts by weight of 1,6-hexanediol having a hydroxyl group at the end and 0.3 to 0.7 parts by weight of 1-methylamino-2,3-propanediol are mixed and stirred at a speed of 60 to 80 rpm for 20 to 30 minutes, followed by reaction. After adding 0.5 to 1.5 parts by weight of aliphatic isocyanate at a temperature of 60 to 70 ° C., the mixture is stirred and reacted at 60 to 80 rpm for 1.5 to 2.5 hours to prepare a polyurethane diol oligomer having a number average molecular weight of 450 to 550.

In the step (S1) of the present invention, the ionic group constituting the mixture having a hydroxyl group at the terminal is used in the synthesis for improving hydrolysis resistance, dimethylol propionic acid may be used, and it is preferable to use 0.17 to 0.22 moles. If the amount is less than 0.17 moles emulsification and water dispersion stability may be lowered, if exceeding 0.22 moles hydrolysis resistance is lowered.

In particular, in the present invention, the content of the ionic group used in the synthesis for improving hydrolysis resistance is 0.17 to 0.22 moles, when converted to weight%, using 2.5% by weight or less relative to the total solids of the solvent-free aqueous polyurethane emulsion. It is preferable to use, and most preferably, 1.8 to 2.0 wt% is used.

And the isocyanate used in the step (S1) of the present invention is preferably used 1.15 ~ 1.5 moles per 1 mole of the mixture having a hydroxyl group at the terminal. When the amount of use is less than 1.15 moles, the adhesive property of the adhesive is inferior, and when the amount is more than 1.5 moles, the dispersion stability is lowered.

As the diisocyanate, an aromatic aliphatic diisocyanate which does not generate side reactions at high temperature should be used to improve discoloration and to prepare a solvent-free aqueous polyurethane emulsion, and as the usable aromatic aliphatic diisocyanate, 1,3- or 1,4-xylene diisocyanate or mixtures thereof, ω, ω'-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-bis (1-isocyanate-1-methylethyl) benzene (common name ; Tetramethyl styrene diisocyanate) can be used by selecting one or more.

In addition, the NCO / OH ratio of the polyurethane prepolymer synthesized by reacting a polyol, a monomer diol, a polyurethane diol oligomer and an ionic group with a diisocyanate as a mixture having a hydroxyl group at the terminal in step (S1) is preferably 1.15 to 1.5. Do.

In the step (S1), the mixture having the hydroxyl group at the terminal and the diisocyanate are reacted with sufficient stirring for 3 to 4.5 hours at a temperature of 80 to 120 ° C to prepare a polyurethane prepolymer.

The neutralizer used in the step (S2) of the present invention is used to neutralize the polyurethane prepolymer prepared in the step (S1), it is preferable to use in a ratio of 1: 1 with the amount of the ionic group. If the amount of use is less than the amount of the ionic group, the water dispersion stability is lowered. If the amount of use is more than the amount of the ionic group, the storage stability of the synthesized emulsion is lowered.

The neutralizing agent may be selected from one or more selected from ammonia water, dimethylaminoethanol, N-methylmorpholine, and triethylamine.

In the step (S2), the polyurethane prepolymer prepared in the step (S1) is cooled to 25 to 30 ° C., and then sufficiently stirred for 1 to 2 hours using a neutralizing agent to prepare an emulsified prepolymer.

The water used in the step (S3) of the present invention is used to emulsify the self-emulsifying prepolymer prepared in the step (S2), wherein the water used to disperse the polyurethane prepolymer in the present invention is particularly Although not limited, it is preferable to use so that solid content of the prepared solvent-free aqueous polyurethane emulsion may be 25 to 60 weight%.

The chain extender used in the step (S3) of the present invention is used to chain-extend the self-emulsifying prepolymer prepared in the step (S2) to prepare a solvent-free aqueous polyurethane emulsion, and a mixture having a hydroxyl group at the terminal. It is preferable to use 0.05-0.5 mol with respect to 1 mol. If the amount is less than 0.05 mole, the chain extending effect is lowered and the adhesive property is lowered. If the amount is more than 0.5 mole, the emulsion state of the emulsion is poor and the storage stability is poor, and the hydrolysis resistance is deteriorated.

The chain extender may be used a monomer amine, the monomer amine used is a substance containing two or more primary or secondary amino groups, hydrazine, ethylene diamine, isopropylenediamine, diethylene triamine, tri One or more of ethylene tetraamine and diaminodiphenylmethane can be selected and used.

The step (S3) is preferably stirred for 1 to 2 hours at a temperature of 18 ~ 30 ℃ for chain extension of the self-emulsifying prepolymer prepared in the step (S2) to prepare a solvent-free aqueous polyurethane emulsion.

And in this invention, a viscosity modifier, a hardening | curing agent, an antifoamer, antioxidant, an antioxidant, etc. can be added as an additive as needed.

And the solvent-free aqueous polyurethane emulsion prepared through the step (S3) is preferably a number average molecular weight of 20,000 ~ 75,000, solid content of 25 ~ 60% by weight.

The present invention also relates to a solvent-free aqueous polyurethane emulsion having excellent hydrolysis resistance, which is produced by the above method.

However, since the structure of the solvent-free aqueous polyurethane emulsion has been described above in detail, the detailed description thereof will be omitted.

The solvent-free aqueous polyurethane emulsion prepared as described above may further include a curing agent when used as an adhesive, and the curing agent is not particularly limited, and a conventionally used curing agent may be appropriately applied.

The solvent-free aqueous polyurethane emulsion according to the present invention may be used by various applications such as adhesives for bonding rubber, leather, plastic and shoe parts.

Therefore, the present invention is a mixture having a hydroxyl group at the terminal, by using a polyol, a polyurethane diol oligomer and a monomer diol together, by using a minimum of the ionic group to introduce a hydrophilic group to lower the water stability, very hydrolysis resistance Not only is it excellent in adhesiveness and water dispersion stability, but also it does not require solvent removal process because it does not use organic solvent, so the work process is shortened, it is less harmful to human body, and it is eco-friendly solvent-free aqueous poly It is possible to provide a process for preparing a urethane emulsion and a solvent-free aqueous polyurethane emulsion prepared by the method.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not necessarily limited only to the following Examples.

1. Preparation of solvent-free aqueous polyurethane emulsion composition

Solvent-free aqueous polyurethane emulsions of Examples 1 to 5 and Comparative Examples 1 to 5 were prepared.

(Example 1)

0.3 mol of polyester polyol of 1,4-butanediol / adipic acid having a molecular weight of 2,000, 0.2 mol of polycaprolactone diol having a molecular weight of 2,000, 0.13 mol of 1,6-hexanediol, 0.15 mole of polyurethane diol oligomer, 0.22 mole of dimethylol propionic acid, and 1.35 mole of tetramethylxylene diisocyanate were added thereto, followed by reaction at 100 ° C. for 4 hours to prepare a carboxyl isocyanate type polyurethane prepolymer. The prepared polyurethane prepolymer was cooled to 30 ° C., neutralized by addition of 0.22 mol of triethylamine, and emulsified for 1.5 hours by slowly adding 1,100 g of water while rapidly stirring the neutralized self-emulsifying polyurethane prepolymer. 0.35 mole of diamine was mixed with water and slowly added dropwise, followed by chain reaction for 1 hour to prepare a solvent-free aqueous polyurethane emulsion composition.

(Example 2)

0.3 mol of 1,4-butanediol / adipic acid polyester polyol with molecular weight 2,000, 0.2 mol of polycaprolactone diol with molecular weight 2,000, 0.13 mol of 1,4-butanediol, poly 0.15 mole of urethane diol oligomer, 0.2 mole of dimethylol propionic acid, and 1.3 mole of tetramethylstyrene diisocyanate were added thereto, followed by reaction at 100 ° C. for 4 hours to prepare a carboxyl isocyanate type polyurethane prepolymer. The prepared polyurethane prepolymer was cooled to 30 ° C., neutralized by adding 0.2 mol of triethylamine, and emulsified for 1.5 hours by slowly adding 1,100 g of water while rapidly stirring the neutralized self-emulsifying polyurethane prepolymer. 0.3 mole of diamine was mixed with water, and slowly added dropwise, followed by chain reaction for 1 hour to prepare a solvent-free aqueous polyurethane emulsion composition.

(Example 3)

0.4 mol of 1,4-butanediol / adipic acid polyester polyol with a molecular weight of 2,000, 0.1 mol of polycaprolactone diol with a molecular weight of 2,000, 0.13 mol of 1,6-hexanediol, 0.15 mole of polyurethane diol oligomer, 0.22 mole of dimethylol propionic acid, and 1.35 mole of tetramethylxylene diisocyanate were added thereto, followed by reaction at 100 ° C. for 4 hours to prepare a carboxyl isocyanate type polyurethane prepolymer. The prepared polyurethane prepolymer was cooled to 30 ° C., neutralized by addition of 0.22 mol of triethylamine, and emulsified for 1.5 hours by slowly adding 1,100 g of water while rapidly stirring the neutralized self-emulsifying polyurethane prepolymer. 0.35 mole of diamine was mixed with water and slowly added dropwise, followed by chain reaction for 1 hour to prepare a solvent-free aqueous polyurethane emulsion composition.

(Example 4)

A solvent-free aqueous polyurethane emulsion composition was prepared under the same conditions as in Example 1 except that 0.5 mole of polyester polyol was used in the polyol and no polycaprolactone diol was used.

(Example 5)

A solventless aqueous polyurethane emulsion composition was prepared under the same conditions as in Example 1 except that isopropylenediamine was used as the chain extender.

(Comparative Example 1)

0.45 mol of 1,4-butanediol / adipic acid polyester polyol with a molecular weight of 2,000, 0.2 mol of polycaprolactone diol with a molecular weight of 2,000, 0.13 mol of 1,6-hexanediol, A carboxyl isocyanate type polyurethane prepolymer was prepared by adding 0.22 mol of dimethylol propionic acid and 1.35 mol of tetramethylstyrene diisocyanate for 4 hours at 100 ° C. The prepared polyurethane prepolymer was cooled to 30 ° C., neutralized by addition of 0.22 mol of triethylamine, and emulsified for 1.5 hours by slowly adding 1,100 g of water while rapidly stirring the neutralized self-emulsifying polyurethane prepolymer. 0.35 mole of diamine was mixed with water and slowly added dropwise, followed by chain reaction for 1 hour to prepare a solvent-free aqueous polyurethane emulsion composition.

(Comparative Example 2)

0.3 mol of polyester polyol of 1,4-butanediol / adipic acid having a molecular weight of 2,000, 0.2 mol of polycaprolactone diol having a molecular weight of 2,000, 0.13 mol of 1,6-hexanediol, 0.1 mole of polyurethane diol oligomer, 0.27 mole of dimethylol propionic acid, and 1.35 mole of tetramethylxylene diisocyanate were added thereto, followed by reaction at 100 ° C. for 4 hours to prepare a carboxyl terminal isocyanate type polyurethane prepolymer. The prepared polyurethane prepolymer was cooled to 30 ° C., neutralized by adding 0.27 mole of triethylamine, and emulsified for 1.5 hours by slowly adding 1,100 g of water while rapidly stirring the neutralized self-emulsifying polyurethane prepolymer. 0.35 mole of diamine was mixed with water and slowly added dropwise, followed by chain reaction for 1 hour to prepare a solvent-free aqueous polyurethane emulsion composition.

(Comparative Example 3)

0.25 mol 1,4-butanediol / adipic acid polyester polyol with molecular weight 2,000, 0.38 mol polycaprolactone diol with molecular weight 2,000, 0.05 mol polyurethane diol oligomer, dimethylol A carboxyl group-terminated isocyanate type polyurethane prepolymer was prepared by adding 0.22 mol of propionic acid and 1.35 mol of tetramethylstyrene diisocyanate for 4 hours at 100 ° C. The prepared polyurethane prepolymer was cooled to 30 ° C., neutralized by addition of 0.22 mol of triethylamine, and emulsified for 1.5 hours by slowly adding 1,100 g of water while rapidly stirring the neutralized self-emulsifying polyurethane prepolymer. 0.35 mole of diamine was mixed with water and slowly added dropwise, followed by chain reaction for 1 hour to prepare a solvent-free aqueous polyurethane emulsion composition.

(Comparative Example 4)

0.5 mol of 1,4-butanediol / adipic acid polyester polyol, 0.2 mol of polyurethane diol oligomer, 0.3 mol of dimethylol propionic acid, 2 mol of tetramethylstyrene diisocyanate The reaction was carried out at 100 ° C. for 4 hours to prepare a carboxyl terminal isocyanate type polyurethane prepolymer. The prepared polyurethane prepolymer was cooled to 30 ° C., neutralized by addition of 0.3 mole of triethylamine, and emulsified for 1.5 hours by slowly adding 1,100 g of water while rapidly stirring the neutralized self-emulsifying polyurethane prepolymer. 1 mole of diamine was mixed with water and slowly added dropwise, followed by chain reaction for 1 hour to prepare a solvent-free aqueous polyurethane emulsion composition.

(Comparative Example 5)

An aqueous polyurethane emulsion (NP-57, NANPAO), which is currently used as an adhesive for shoes, was used.

However, the polyurethane diol oligomer used in Examples and Comparative Examples herein was mixed with 0.7 parts by weight of 1,6-hexanediol and 0.6 parts by weight of 1-methylamino-2,3-propanediol and stirred at 70 rpm for 20 minutes. In addition, 1.0 parts by weight of aliphatic isocyanate was added at a reaction temperature of 70 ° C., followed by stirring and reacting at 70 rpm for 2 hours to use a polyurethane diol oligomer having a number average molecular weight of 500.

2. Performance Evaluation of Solvent-free Water-based Polyurethane Emulsion

The emulsion of each of the Examples and Comparative Examples prepared above was measured by the following method, initial adhesion, state adhesion, heat resistance, water dispersion stability, water resistance, and hydrolysis resistance, the results are shown in [Table 1] It was.

1) Adhesive

The material used in this experiment was the outsole material (rubber) used by domestic shoemakers.

2) Preparation of Adhesive Specimen

The prepared adherend was cut into a size of 100 × 10 mm, washed with toluene, and dried. A water-based primer (PR-505, Henkel) was once applied to the adhesive side of the rubber and dried by heat treatment at 55 ° C. for 5 minutes. Then, 5 wt% of an aqueous curing agent (ARF-40, Henkel) was added to each of the aqueous polyurethane emulsions of Examples and Comparative Examples, applied to the adherends, dried by heat treatment at 55 ° C. for 5 minutes, and then dried using a hand roller. The adhesive was applied by applying a load of 4 kgf.

3) initial adhesion

After the prepared adhesive specimen was allowed to stand at room temperature for 30 minutes, the adhesive strength was evaluated by peeling at a rate of 100 ± 20 mm / min using a universal tensile tester. Five adhesive specimens were measured and their average value was measured.

4) State Adhesion

The prepared adhesive specimens were left at room temperature for 24 hours and then peeled at a rate of 100 ± 20 mm / min using a universal tensile tester to evaluate the adhesive strength. Five adhesive specimens were measured and their average value was measured.

5) Heat resistant adhesion

The prepared adhesive specimen was left at room temperature for 24 hours, and then the adhesive specimen was weighed at 1 ° C. under a temperature of 90 ° C., and left for 1 hour to measure a peeled distance. Five adhesive specimens were measured and their average value was measured.

6) water resistance

After leaving the prepared adhesive specimens at room temperature for 24 hours, the adhesive specimens were immersed in water at room temperature for 48 hours, and then dried at room temperature, and then peeled at 100 ± 20㎜ / min using a universal tensile tester. Adhesion strength was evaluated. Five adhesive specimens were measured and their average value was measured.

7) Hydrolysis resistance

After leaving the prepared adhesive specimens at room temperature for 24 hours, the adhesive specimens were left for 7 days in a constant temperature and humidity chamber at 70 ° C and 95% humidity, and then peeled at 100 ± 20㎜ / min using a universal tensile tester. Was evaluated. Five adhesive specimens were measured and their average value was measured.

8) Dispersion Stability

The prepared solvent-free aqueous polyurethane emulsion was left at 30 ° C. for 1 month, and then the emulsion state was observed.

division Example Comparative example One 2 3 4 5 One 2 3 4 5 Initial adhesion
(kgf / cm, 30min) 7.6 6.5 6.8 8.2 6.8 5.4 6.3 7.5 - 7.9 State adhesion
(kgf / cm, 24hr) 11.3 9.8 12.4 11.3 13.2 10.3 8.8 9.3 - 11.5 Heat-resistant adhesive force (mm) 10 8 9 10 7 9 10 11 - 10 Water resistance (kgf / cm) 8.7 7.7 9.2 6.5 5.8 5.6 6.6 6.8 - 8.2 Hydrolysis resistance (kgf / cm) 2.0 1.6 1.9 2.1 1.7 0.2 0.4 0.2 - 0.3 Water dispersion stability Good Good Good Good Good Bad Good Good - Good

As shown in Table 1, in the case of the solvent-free aqueous polyurethane emulsion synthesized in Examples 1 to 5, by using a polyol, a polyurethane diol and a monomer diol as a mixture having a hydroxyl group at the terminal, an ionic group The solvent-free polyurethane emulsion prepared with a minimum amount of dimethylol propionic acid was found to have excellent hydrolysis resistance, and good adhesion and water dispersion stability.

However, Comparative Example 1 used 0.65 mol of the mixed amount of polyester polyol and polycaprolactone diol used as a polyol exceeding the use range, and the initial adhesive strength was slightly lower than that of the example, and the water resistance and hydrolysis resistance were very low. It was found that the dispersion stability was poor. In Comparative Example 2, a polyurethane diol oligomer was used below the use range, and ionic acid group dimethylol propionic acid was used over the use range, indicating poor hydrolysis resistance, and Comparative Example 3 did not use monomer diol. As the polyol, the amount of the polyol mixed with polycaprolactone exceeds 0.25, and the amount of the polyol mixed with the polycaprolactone exceeds 0.25, and the amount of the polyol of the polyester polyol is less than 0.3 mole. By use, the solvent-free aqueous polyurethane emulsion synthesized was very poor in hydrolysis resistance.

On the other hand, in Comparative Example 4, a polyurethane diol oligomer, dimethylol propionic acid as an ionic acid group and diisocyanate are used beyond the use range without using monomer diol, and the amount of triethylamine as a neutralizing agent and ethylenediamine as a chain extender is used. In addition, since the use range was exceeded, the emulsion stability decreased during the chain extension of the solvent-free aqueous polyurethane emulsion, aggregates were formed, and evaluation of the performance such as the evaluation of the adhesion was impossible, and the result was not measured.

Comparative Example 5 is a general-purpose water-based polyurethane adhesive, a product that does not use the polyurethane diol oligomer used in the present invention was excellent in the initial adhesive strength and the adhesive strength of the state adhesive strength, but showed very poor hydrolysis resistance.

As described above, the method for preparing a solvent-free aqueous polyurethane emulsion according to the present invention and the solvent-free aqueous polyurethane emulsion prepared by the method have been described through the above-described preferred embodiments, and the superiority thereof has been confirmed. Those skilled in the art will appreciate that various modifications and changes can be made in the present invention without departing from the spirit and scope of the invention as set forth in the claims below.

Claims (13)

As a mixture having a hydroxyl group at the terminal, a polyol, a monomer diol, Preparing a polyurethane prepolymer having an isocyanate group at the molecular end thereof by reacting the polyurethane diol oligomer and dimethylol propionic acid as an ionic group with diisocyanate (S1); Neutralizing the polyurethane prepolymer prepared in step (S1) with a neutralizing agent to prepare a self-emulsifying prepolymer having an NCO / OH ratio of 1.15 to 1.5 (S2); (S3) extending the chain by adding water to the self-emulsifying prepolymer prepared in the step (S2), and emulsifying by adding a chain extender; Manufactured through In the step (S1), the polyol is used by using a polyester polyol alone or a mixture of polyester polyol and polycaprolactone diol, The polyester-based polyol is used by selecting one or more of polyethylene adipate, polybutylene adipate, polyethylene butylene adipate, The polyester polyol and polycaprolactone diol has a number average molecular weight of 2,000 ~ 3,000, In addition, the monomer diol in the step (S1) is used by selecting one or more of ethylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, In addition, the polyurethane diol oligomer in the step (S1) is a compound having a hydroxyl group at the terminal, 0.3 to 0.7 parts by weight of 1,6-hexanediol, 0.3 to 0.7 parts by weight of 1-methylamino-2,3-propanediol, aliphatic Isocyanate is prepared including 0.5 to 1.5 parts by weight, the number average molecular weight is 450 to 550, In addition, in the step (S1), as the diisocyanate, as aromatic aliphatic diisocyanate, 1,3- or 1,4-xylene diisocyanate or mixtures thereof, ω, ω'-diisocyanate-1,4-diethylbenzene, 1 One or more selected from-, 3- or 1,4-bis (1-isocyanate-1-methylethyl) benzene (common name; tetramethyl styrene diisocyanate), In the step (S2), the neutralizing agent is selected from one or more selected from ammonia water, dimethylaminoethanol, N-methylmorpholine, and triethylamine, In the step (S3), the chain extender is a monomer amine-based one selected from hydrazine, ethylene diamine, isopropylene diamine, diethylene triamine, triethylene tetraamine, diaminodiphenylmethane, Use, In addition, the solvent-free aqueous polyurethane emulsion prepared through the step (S3) is a method of producing a solvent-free aqueous polyurethane emulsion, characterized in that the number average molecular weight of 20,000 ~ 75,000. The method of claim 1, In the step (S1), the mixture having a hydroxyl group at the end is 0.46 to 0.59 mol of a polyol, 0.12 to 0.16 mol of a monomer diol, 0.12 to 0.16 mol of a polyurethane diol oligomer and 0.17 to 0.22 mol of an ionic group, and a mixture having a hydroxyl group at the terminal. 1 to 15 moles of diisocyanate per mole, The neutralizing agent of step (S2) is used in a ratio of 1: 1 with the amount of dimethylol propionic acid that is the ionic group, The water of step (S3) is used so that the solid content of the prepared solvent-free aqueous polyurethane emulsion is 25 to 60% by weight, and the chain extender is used at 0.05 to 0.5 mole based on 1 mole of the mixture having a hydroxyl group at the terminal. A method for producing a solvent-free aqueous polyurethane emulsion, characterized in that. delete delete delete delete delete delete delete delete delete delete A solvent-free aqueous polyurethane emulsion, which is prepared by the method of claim 1.