JPH04252202A - Production of aqueous resin - Google Patents

Abstract

PURPOSE:To provide a process for stably producing an aqueous resin having the merits of a urethane resin emulsion and the vinyl polymer emulsion at the same time and giving a coating film having excellent abrasion resistance, adhesivity and weather resistance. CONSTITUTION:A vinyl monomer is dispersed in an aqueous emulsion of a polyurethane in emulsified state and polymerized to obtain the objective aqueous resin. An aqueous resin exhibiting excellent properties for textile impregnation, paper impregnation, water-base paint, water-base ink and protection coating can be stably supplied by this process.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aqueous resin containing a vinyl polymer and polyurethane. The water-based resin obtained by the production method of the present invention provides a coating film with excellent abrasion resistance, adhesion, and weather resistance, so it can be widely used in paints, adhesives, etc., and is suitable for industries that handle them. It is widely used.

0002

[Prior Art] At present, it has become a problem that the organic solvents contained in solution-type products have a negative impact on the human body and the environment. Therefore, it is considered safer for the human body and the environment than solution-based products, and is widely used in paints, fiber treatments, adhesives, etc.

Vinyl polymers such as urethane resins and acrylic resins are well known and actually widely used as resins used in polymer emulsions.

Although urethane resins provide strong films with excellent impact resilience and abrasion resistance, they have drawbacks such as poor weather resistance and alkali resistance.

On the other hand, acrylic resin, which is a typical vinyl polymer, exhibits excellent weather resistance and alkali resistance.
Furthermore, when formed into a coating film, it provides high gloss, but has the drawback of being highly thermoplastic and easily causing blocking.

[0006]

SUMMARY OF THE INVENTION Therefore, in order to take advantage of the advantages of these two types of resins having different properties, various proposals have been made regarding mixing or combining them. For example, mixing both resins mechanically has been practiced, but depending on the resin composition, the emulsions are not compatible with each other, the emulsion lacks stability, and the resin may precipitate. , also in terms of resin performance, there is a problem in that the characteristics of each resin often cancel each other out. In addition, a method has been proposed in which a vinyl monomer is radically polymerized in an aqueous polyurethane emulsion to obtain an aqueous dispersion (for example, JP-A-62-212455). The problem is that it lacks stability when subjected to radical polymerization, making it difficult to obtain a stable dispersion of fine particles.

Under these circumstances, the present inventors conducted intensive research on a method for obtaining an aqueous resin that has excellent abrasion resistance, weather resistance, film-forming properties, and blocking resistance, and is stable even at high concentrations. .

[0008]

[Means for Solving the Problems] As a result of various studies, the present inventors have found that a vinyl monomer emulsion obtained by pre-emulsifying a vinyl monomer with a polyurethane aqueous emulsion is used. The inventors have discovered that the above-mentioned problems can be solved by polymerizing vinyl monomers, leading to the present invention.

That is, the present invention relates to a method for producing an aqueous resin, which comprises adding a vinyl monomer to an aqueous polyurethane emulsion, uniformly emulsifying and dispersing the vinyl monomer, and then polymerizing the vinyl monomer. It is something.

To explain the present invention in more detail, the vinyl monomer to be polymerized is emulsified in advance with the entire amount or a portion of the urethane aqueous emulsion to be used, which is determined depending on the characteristics of the final product. By polymerizing the vinyl monomers present in the aqueous emulsion, a vinyl resin with excellent liquid stability and a urethane resin are mixed and modified to provide a coating film with excellent weather resistance and abrasion resistance. It is very easy to obtain a water-based resin.

The aqueous polyurethane emulsion used in the present invention is produced by a known method, for example, the following method.

That is, first, a diisocyanate, a diol, and a diol having a carboxyl group are subjected to a urethane reaction to prepare a prepolymer.

The diisocyanates used at this time include aromatic diisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, m-phenylene diisocyanate, and xylylene diisocyanate; Examples include aliphatic isocyanates such as methylene diisocyanate, hexamethylene diisocyanate, 1,4 cyclohexylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and isophorone diisocyanate.

Examples of diols include polyethers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, and cyclohexyl dimethanol, and maleic acid. , polyesters obtained by dehydration condensation reaction with polyhydric carboxylic acids such as succinic acid, adipic acid, and phthalic acid, or ring-opening polymerization reaction of cyclic esters, polydiols such as polycarbonate, and ethylene glycol, diethylene glycol, triethylene glycol, 1, 2- Propylene glycol, trimethylene glycol, 1, 3-butylene glycol, tetramethylene glycol, hexamethylene glycol,
Hydrogenated bisphenol A, low molecular weight glycols such as ethylene oxide or propylene oxide adducts of bisphenol A, and carboxyl groups such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid. Examples include diols having

After neutralization, the prepolymer obtained as described above undergoes chain elongation and water is added to form an aqueous polyurethane emulsion, which is used in the present invention.

[0016] Examples of the neutralizing agent used in this case include ammonia, trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, sodium hydroxide, potassium hydroxide, and the like.

Examples of the chain extender include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, and the like.

Examples of vinyl monomers to be emulsified and polymerized in the polyurethane aqueous emulsion include methyl acrylate, ethyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, and di-acrylate. Acrylic esters such as ethylhexyl, octyl acrylate, and nonyl acrylate; methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, and nonyl methacrylate. Acid esters, styrene, p-methylstyrene, α-methylstyrene, chlorostyrene, aromatic vinyl monomers such as vinyltoluene, acrylonitrile,
Unsaturated nitriles such as methacryl nitrile, butadiene, conjugated diolefins such as isoprene, divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, allyl methacrylate, diallyl phthalate,
Multi-vinyl monomers such as trimethylolpropane triacrylate, glycerol diallyl ether, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, amide monomers such as acrylamide, methacrylamide, n-methylolmethacrylamide, β-hydroxylethyl acrylate , n-hydroxyethyl acrylamide, hydroxyl group-containing monomers such as β-hydroxyethyl methacrylate, amino group-containing monomers such as dimethylaminoethyl acrylate, β-aminoethyl vinyl ether, dimethylaminoethyl vinyl ether, glycidyl acrylate, methacrylic acid Examples include glycidyl group-containing monomers such as glycidyl, vinyl monomers such as vinyl acetate, vinyl chloride, and vinylidene chloride.

In order to obtain an excellent water-based resin, as vinyl monomers, methyl acrylate, ethyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, 2-ethylhexyl acrylate, acrylic Acrylic acid esters such as octyl acrylate and nonyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, pentyl methacrylate,
A monomer mixture containing methacrylic acid esters such as hexyl methacrylate, heptyl methacrylate, octyl methacrylate, and nonyl methacrylate as a main component is preferably selected and is preferred for the present invention.

The amount of the aqueous polyurethane emulsion used to emulsify the vinyl monomer is the total amount of the vinyl monomer and the amount of polyurethane in the aqueous polyurethane emulsion (hereinafter referred to as the total amount of resin). The amount is preferably such that 10 to 90% of the amount is polyurethane.
The entire amount or a portion of the vinyl monomer, which accounts for 90 to 10% of the total resin amount, is emulsified.

If the proportion of polyurethane in the aqueous polyurethane emulsion used in preparing the vinyl monomer emulsion is lower than 10% of the total resin amount, it is difficult to obtain a stable aqueous resin emulsion. In addition, if the proportion of polyurethane in the aqueous polyurethane emulsion exceeds 90% of the total resin,
It is difficult to impart the characteristics of vinyl polymers, such as gloss and weather resistance, to the vinyl/urethane composite aqueous resin obtained by polymerization.

Radical polymerization is preferred as a method for polymerizing vinyl monomers, and examples of initiators for radical polymerization include potassium persulfate, ammonium persulfate, azobiscyanovaleric acid, t-butyl hydroperoxide, azoisobutyronitrile, etc. These are suitably used in a range of 0.1% to 5% based on the total amount of vinyl monomers.

[0023]

[Function] According to the production method of the present invention, a stable aqueous resin can be produced without using any surfactant used in ordinary emulsion polymerization. This effect was discovered for the first time by the present inventors. Of course, this does not preclude the use of a surfactant in combination, if necessary.

[0024]

EXAMPLES The present invention will be explained in more detail below using reference examples, working examples, and comparative examples.

Reference example polytetramethylene glycol (molecular weight 1000) 24
7g, isophorone diisocyanate 124g, dimethylolpropionic acid 24g and methyl ethyl ketone 110
g was placed in a reactor equipped with a reflux condenser, a thermometer, and a stirring device, and a urethane reaction was carried out at 75 to 83° C. for 4 hours to prepare a prepolymer. Next, 18 g of triethylamine was added to this prepolymer to neutralize it, 582 g of distilled water containing 5 g of diethylenetriamine was added, and methyl ethyl ketone was removed under reduced pressure to obtain a polyurethane aqueous emulsion A.

Polyurethane aqueous emulsions B, C, D, and E were prepared in the same manner using the raw materials shown in Table 1, respectively.

[0027]

[Table 1] Note: Abbreviations in the table indicate the following compounds. PTMG: Polytetramethylene glycol PP
G: Polypropylene glycol PHMA
: Polyhexamethylene adipate PCD
: Polycarbonate diol DCHMDI: Dicyclohexylmethane diisocyanate

Example 1 290 g of the aqueous polyurethane emulsion A synthesized in Reference Example and 80 g of distilled water are placed in a 1 L beaker and stirred using a stirrer. Into this, 170 g of methyl methacrylate, 100 g of butyl acrylate, 2 g of azoisobutyronitrile.
A mixed solution consisting of was gradually added to prepare an emulsion of vinyl monomer. 358 g of distilled water was added to a reactor equipped with a reflux condenser, a nitrogen introduction tube, a thermometer, and a stirring device, and after heating to 75°C, the urethane emulsion of the vinyl monomer was added dropwise over 5 hours. did. After the dropwise addition was completed, the reaction solution was kept at 75° C. for 2 hours to complete the polymerization reaction. An aqueous resin having a nonvolatile content of 38.5% and a viscosity of 15 cps was obtained.

Examples 2 to 5 The aqueous resins shown in Table 2 (Examples 2 to 5) were prepared in the same manner as in Example 1.
) was prepared.

Example 6 150 g of the aqueous polyurethane emulsion D synthesized in Reference Example and 100 g of distilled water are placed in a 1 L beaker and stirred using a stirrer. Into this, 168 g of styrene, 100 g of butyl acrylate, 2 g of 2-ethylhexyl acrylate,
A mixed solution consisting of 2 g of glycidyl methacrylate and 2 g of azoisobutyronitrile was gradually added to prepare an emulsion of a vinyl monomer. 140 g of polyurethane aqueous emulsion C and 336 g of distilled water were added to a reactor equipped with a reflux condenser tube, a nitrogen introduction tube, a thermometer, and a stirring device, and after heating to 75°C, a urethane emulsion of the vinyl monomer was formed. The liquid was added dropwise over 5 hours. After the dropwise addition was completed, the reaction solution was kept at 75° C. for 2 hours to complete the polymerization reaction. Non-volatile content 39.0
% and a viscosity of 18 cps was obtained.

Examples 7 to 8 The aqueous resins shown in Table 2 (Examples 7 and 8) were prepared in the same manner as in Example 6.
) was prepared.

[0032]

[Table 2] Note: Abbreviations in the table indicate the following compounds. ST: styrene, MMA: methyl methacrylate, BA:
Butyl acrylate, H EMA: 2-ethylhexyl acrylate, GMA: Glycidyl methacrylate, AIBN: Azoisobutyronitrile

Comparative Example 1 Aqueous urethane resin A29 synthesized in Reference Example in a reactor equipped with a reflux condenser, nitrogen introduction tube, thermometer and stirring device.
0g and 404g of distilled water were added, and the mixture was heated to 65°C. A liquid mixture consisting of 170 g of methyl methacrylate and 100 g of butyl acrylate was added dropwise to this reactor. Simultaneously with this dropwise addition of the vinyl monomer, a 10% aqueous solution of t-butyl hydride peroxide prepared in advance 1
8 g and 18 g of a 10% aqueous solution of sodium formaldehyde sulfoxylate were also added dropwise. The resin began to precipitate about 2 hours after the start of the dropwise addition of the vinyl monomer, and at 4 hours after the start of the dropwise addition, so much resin had precipitated that it became difficult to stir the inside of the reactor, so the reaction was stopped.

Comparative Examples 2 and 3 Polymerizations shown in Table 3 (Comparative Examples 2 and 3) were carried out in the same manner as in Comparative Example 1. Similarly to Comparative Example 1, no aqueous resin was obtained in Comparative Example 2. Only in the case of Comparative Example 3, in which the proportion of the aqueous polyurethane emulsion was extremely high, an aqueous resin was obtained even in the method of Comparative Example 1.

Comparative Examples 4-5 Aqueous resins (Comparative Examples 4-5) were prepared in the same manner as in Comparative Example 1.

[0036]

[Table 3] Note: Abbreviations in the table indicate the following compounds. ST: styrene, MMA: methyl methacrylate, BA:
Butyl acrylate, H EMA: 2-ethylhexyl acrylate, GMA: glycidyl methacrylate, PBH: t-butyl hydroperoxide, SFS: sodium formaldehyde sulfoxylate, KPS: potassium persulfate

0037
]Performance test method and evaluation results 1) Storage stability The polyurethane aqueous emulsions and aqueous resins obtained in Reference Examples, Examples, and Comparative Examples were left at room temperature for 3 months, and the stability of the liquids was visually evaluated.

2) High-temperature stability The aqueous polyurethane emulsions and aqueous resins obtained in Reference Examples, Examples, and Comparative Examples were left at 50° C. for 14 days, and the stability of the liquids was visually evaluated.

3) Freeze Stability The aqueous polyurethane emulsions and aqueous resins obtained in Reference Examples, Examples, and Comparative Examples were repeatedly frozen and thawed three times, and the stability of the liquids was visually evaluated.

4) Marlon test 50 g of the aqueous polyurethane emulsions and aqueous resins obtained in Reference Examples, Examples and Comparative Examples were subjected to Marlon test for 20 minutes under 10 atmospheres, and the amount of precipitated resin was evaluated.

5) Membrane strength It was carried out in accordance with JIS (K6301).

6) Elasticity of Membrane Membranes prepared from the aqueous polyurethane emulsions and aqueous resins obtained in Reference Examples, Examples, and Comparative Examples were evaluated by touch.

7) Acid resistance Membranes prepared from the aqueous polyurethane emulsions and aqueous resins obtained in Reference Examples, Examples, and Comparative Examples were immersed in 5% hydrochloric acid for 1 hour and visually evaluated.

8) Alkali resistance Membranes prepared from the aqueous polyurethane emulsions and aqueous resins shown in Reference Examples, Examples and Comparative Examples were dissolved in 5% caustic soda at 1%
It was immersed for a period of time and visually evaluated.

9) Humid and heat resistance Membranes prepared from the polyurethane aqueous emulsions and aqueous resins shown in Reference Examples, Examples and Comparative Examples were heated at 70°C and relative humidity 9.
The film strength was measured and evaluated after being left for one week under a 5% condition.

10) Weather resistance The membranes prepared from the aqueous polyurethane emulsions and aqueous resins shown in Reference Examples, Examples and Comparative Examples were left in a Weathero tester for 100 hours, and then the membrane strength was measured and evaluated. went.

11) Blocking resistance The aqueous polyurethane emulsions and aqueous resins obtained in Reference Examples, Examples, and Comparative Examples were applied to a thickness of 20 μm, dried, and another high-quality paper was placed on top of it. After being left at 40° C. for 3 hours under a pressure of 4 kg/cm 2 , the degree of peeling of the paper was observed.

The physical properties of the aqueous polyurethane emulsions and aqueous resins obtained by the production methods shown in Reference Examples, Examples, and Comparative Examples, as well as the coatings obtained from them, were measured by the methods described above, and the results are presented. 4 and Table 5.

The evaluation criteria in Tables 4 and 5 are as follows. ◎ (No abnormalities, excellent) ○ (Almost no abnormalities, somewhat excellent) △ (Some abnormalities, average) × (No performance as a film, poor)

[0050]

[Table 4]

[0051]

[Table 5]

[0052]

[Effects of the invention] The aqueous resins obtained by the production method of the present invention have good stability, and the films obtained from them are strong and fast.
It has excellent elasticity and weather resistance, and can be expected to be used in a wide variety of applications, including fiber impregnation, paper impregnation, water-based paints, water-based inks, and protective coatings.

Claims (1)

[Claims] 1. A method for producing an aqueous resin, which comprises adding a vinyl monomer to an aqueous polyurethane emulsion, uniformly emulsifying and dispersing the vinyl monomer, and then polymerizing the vinyl monomer.