JPS6011736B2 - Manufacturing method of aqueous dispersion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing aqueous dispersions of water-insoluble thermoplastic resins and/or rubbery substances.

Water-insoluble thermoplastics and/or rubbery substances (
Polyvinyl alcohol resin or its hydrated material is added to the raw polymer material (hereinafter sometimes referred to as the raw material polymer material), mixed into a bran, and then mixed with water to produce a thermoplastic resin or/and rubber-like material. An aqueous dispersion can be obtained. In this case, by adding an appropriate amount of water (preferably adding gradually) during kneading, it is possible to make the kneading process smoother and to reduce the amount of polypynyl alcohol resin that needs to be added. However, when an aqueous dispersion is produced by this method, a large amount of foam is generated in the resulting aqueous dispersion, both when water is not added during crane kneading and when water is added during trench kneading. . At this time, the generated foam cannot be extinguished even by adding various antifoaming agents, and is also mechanically stable. The generation of foam not only causes various problems in the storage, transportation and use of the aqueous dispersion, but also adversely affects the properties of products to be manufactured using the aqueous dispersion. As a result of various studies to solve the above-mentioned problems, the inventors of the present invention have found that the object can be achieved by a method that includes defoaming by crosstalk in a steam atmosphere.

That is, according to the present inventor, a polyvinyl alcohol resin or a water-containing substance thereof is added to a water-insoluble thermoplastic resin or/and a rubbery substance and kneaded, preferably water is added during the kneading, and the mixture is kneaded after the kneading. When producing an aqueous dispersion of thermoplastic resin or/and rubber-like material by mixing the material with water as necessary, defoaming is performed at least in the final stage of the kneading by mixing in a steam atmosphere. This makes it possible to produce aqueous dispersions with effectively reduced foam formation.

When performing defoaming by kneading in a steam atmosphere according to the present invention, it is more effective to circulate steam intermittently or continuously so that steam does not stagnate around the concentrated material. Crane training in air currents is not essential. There is no problem in carrying out cross-crossing in a steam atmosphere during the entire period of cross-twilling, but when kneading is carried out while gradually adding raw material polymeric substances and/or polypynyl alcohol resin, it is common to mix them. After finishing the preparation, kneading may be continued in a steam atmosphere. It is preferable to knead in a steam atmosphere for as long as possible, including the final stage of the moat bran period after finishing the preparation of the raw material polymer material and polyvinyl alcohol resin. If kneading is carried out in a steam atmosphere for about 10 to 20 minutes immediately before the kneading is completed, the above-mentioned defoaming effect will be substantially achieved. The thermoplastic resin and rubbery substance used as raw polymeric substances in the present invention are substantially insoluble under the operating conditions of the process of the present invention, and are kneaded with the polyvinyl alcohol resin without significant decomposition. For example, polyethylene, polypropylene, polystyrene, polyamide (nylon, nylon 6
6), polyester (e.g. polyethylene terephthalate, polyvinyl chloride, natural rubber, synthetic rubber (e.g. polyisoprene, polybutadiene, styrene-butadiene copolymer rubber, styrene-isoprene copolymer rubber, chloroprene rubber), silicone rubber, Examples include polyurethane rubber, acrylic rubber, and butyl rubber.

Any of these can be used alone or in combination of two or more. These raw polymeric substances may contain appropriate additives such as fillers, anti-aging agents, stabilizers, and tackifiers. The polyvinyl alcohol resin used in the present invention is a queso compound of a homopolymer of vinyl ester (preferably vinyl acetate), mainly consisting of vinyl ester (preferably vinyl acetate), and ethylene, propylene, crotonic acid, acrylic acid, and methacrylic acid. , a saponified product of a vinylester 3 copolymer consisting of a copolymerizable monomer such as maleic acid (maleic anhydride), and acetal compounds of these saponified products.

Among these polyvinyl alcohol resins, the degree of polymerization is 4.
Polyvinyl alcohol having a saponification degree of 70 to 98 mol% is particularly preferred. 4. The required amount of polyvinyl alcohol resin to be added to the raw material polymer substance varies depending on the type of raw material polymer substance, the type of polyvinyl alcohol resin, whether or not water is added to the mixed rice bran, and should be fixed uniformly. I can't. However, in general, it is possible to produce an aqueous dispersion by adding about 3 parts by weight or more of polyvinyl alcohol resin to 10 parts by weight of the raw polymer material, and it is possible to produce a water-containing polyvinyl alcohol resin (
i.e. a mixture of polyvinyl alcohol resin and water)
The amount of polyvinyl alcohol resin that needs to be added can be reduced to about 2 parts by weight per 10 parts by weight of the raw polymeric material by using or adding water during kneading (particularly by adding water during drilling). can. Increasing the blending ratio of polyvinyl alcohol resin to the raw material polymer does not pose any problem for the production of the aqueous dispersion itself. The polyvinyl alcohol resin may be selected arbitrarily, taking into account the permissible amount of polyvinyl alcohol resin in the product to be obtained from the raw material.In order to maintain the useful properties of the raw material polymer material, it is generally It is desirable to add polypynyl alcohol in an amount equal to or less than the amount (weight) of the polymeric substance, and in particular, in order to maintain the rubbery elasticity of the rubbery substance, polypynyl alcohol is added to 10 parts by weight of the rubbery substance. It is desirable that the amount of resin be 25 parts by weight or less.When a certain type of thermoplastic resin, such as a polystyrene resin, is used as a raw polymer material, a large amount of polyvinyl alcohol, such as 3 times the weight of the thermoplastic resin, is used. Resin can also be added.When using hydrous polyvinyl alcohol resin or adding water during cross-conducting, the fluidity of water and polyvinyl alcohol resin is lower than the fluidity of the raw polymer material under drilling conditions. If a large amount of water, which increases the fluidity of the system composed of It is desirable to avoid adding a large amount of water beyond the amount that imparts appropriate fluidity (plasticity) to the polyvinyl alcohol resin until a nearly homogeneous kneaded product is obtained.A nearly homogeneous kneaded product is obtained. Afterwards, it is preferable to add water (preferably gradually) and knead it.This progresses the fragmentation of the raw polymeric material and facilitates the preparation of an aqueous dispersion containing dispersoids with smaller particle sizes. Depending on the kneading machine used, it is not possible to add a large amount of water during kneading.
For this purpose and from the viewpoint of workability, generally the kneaded material is removed from the kneader once a thick aqueous dispersion is formed without dilution to the desired solids concentration, and this is further mixed with water. It is desirable to dilute. When kneading is carried out in a system where little or no liquid water coexists, it is essential to disperse the mixed material into the water by, for example, throwing it into the water. In carrying out the present invention, any kneading machine Z may be used as long as it is capable of sufficiently kneading and mixing the raw polymer material and the polyvinyl alcohol resin, such as a mixing roll or a viscobury type kneading machine. etc. are available. However, when performing defoaming by kneading in a steam atmosphere, it may be necessary to use a closed-type kneader from the beginning or during the process to create a steam atmosphere. It is necessary to modify or install additional equipment before use. The kneading temperature may be any temperature that allows kneading and does not cause significant decomposition of either the raw material polymer material or the polyvinyl alcohol resin.
The temperature is selected within the range of ~250°C, but it is also possible to use a lower temperature if a raw polymeric material with a sufficiently low secondary transition temperature, such as a rubbery substance, is used. However, in order to maintain a steam atmosphere, the temperature is preferably 10,000 or more, and particularly in the final stage of kneading, it is preferable to raise the temperature to 100oC or higher for about 10 to 2 minutes and blow steam into the mixture. The aqueous dispersion obtained by the method of the present invention can be used in many fields, such as adhesives, fiber treatment agents, bond products, coating compositions, and foams, depending on the raw polymer material used. .

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by these Examples.

Note that parts in the examples mean parts by weight unless otherwise specified. 3 Examples 1 Using an open kneader with a capacity of 60 cc, a synthetic polysobrene containing antiaging agent (BHT) of lphr (phr: parts by weight per 100 parts by weight of rubber) (trade name Clabrane-10, manufactured by Clary Soprene Co., Ltd.) 45 After mixing rice bran for 18 minutes at 90qo in the evening, add polyvinyl alcohol (Kuraray Poval #217,
A mixture consisting of 5 parts (polymerization degree: 1700, saponification degree: 88 mol%) and 5 parts of water was added little by little and mixed, and a white exposed product was obtained.

At this time, cover the raw material inlet with a sealing lid equipped with a steam inlet, water addition port, and steam outlet, and mix at 9 picoC while blowing steam into the kneader and adding water little by little. continued. After about 5 hours of water was added, a milky white, viscous mixture was obtained. The hawking time under the steam atmosphere was about 20 minutes. Take out the kneaded material from the strainer,
When the mixture was poured into water for 50 minutes and stirred, an aqueous dispersion was obtained. The resulting aqueous dispersion contained almost no bubbles, and no bubbles rose to the surface even after being left for about 2 hours. The particle size of the dispersed particles is 0.1 to 2 French, and in a freeze-thaw stability test in which this aqueous dispersion was kept at -15q C for 1 hour and then left at 3000 C for 1 hour, no abnormalities were observed and it was stable. Met. The breaking strength of the dry film obtained from this aqueous dispersion is 10k9/block, and the breaking elongation is 470%.
Met. For comparison, an aqueous dispersion was produced in the same manner as above except that no steam was blown into the dispersion. There were many fine bubbles in the resulting aqueous dispersion, and when it was left to stand for about 30 minutes, a large amount of air bubbles appeared on the liquid surface. Bubbles rose to the surface. Example 2 10 parts of styrene-butadiene flock copolymer rubber (trade name: Tuffprene, manufactured by Asahi Kasei) and polyvinyl alcohol (
Kuraray Bobal #205, degree of polymerization 500, degree of saponification 88
mol%) 25 parts at 120 qo in a completely closed kneader.
Knead for 8 minutes, then add 5 parts of water little by little to make 1.
Kneading was continued for a period of time, during which time the gas remaining in the kneader was exhausted five times.

Thereafter, the temperature was reduced to 9,500 ml, and 25 parts of water was added to obtain a milky white kneaded product. When this was diluted with 100 parts of water, a stable aqueous dispersion containing almost no air bubbles was obtained. The particle size of the dispersed particles was 0.1 to 1, and this aqueous dispersion was stable without forming any coagulum even in the freeze-thaw test described in Example 1. Furthermore, when this aqueous dispersion was left to stand for about 2 hours after production, hardly any floating of bubbles was observed. Example 3 Using the same kneading machine as in Example 1, 100 parts of natural rubber and 7 parts of a terbene-based adhesion aid (trade name YS Resin PX #700, manufactured by Yasukawa Oil Co., Ltd.) were kneaded at 9000 for 18 minutes. A saponified product of ethylene-vinyl acetate copolymer with an ethylene content of 3 mol% (degree of saponification of the vinyl acetate portion is 98 mol%)
) and 15 parts of water were added and kneaded for about 30 minutes to obtain a pale yellow kneaded product.

Then, in the same manner as in Example 1, while blowing steam, 40 parts of water was added in small portions and thickened for about 1 hour, resulting in a paste-like mixture. When this was taken out from the kneader and poured into 100 parts of water, a milky white aqueous dispersion was obtained. The particle size of the dispersed particles was 0.1 to 1. This aqueous dispersion contains almost no air bubbles and about 2
Although it was left for a while, no bubbles were observed to float. Z When this aqueous dispersion was applied on a glass plate and dried, it showed great tackiness. This was soaked in water, but it was not re-emulsified. Even when polyisoprene rubber was used instead of natural rubber, a bubble-free aqueous dispersion was similarly obtained.
Z Example 4 Thermoplastic polyurethane (trade name Paraprene Berets 2$, manufactured by Nippon Polyurethane Industries)
100 parts and polyvinyl alcohol (Kuraray Poval #2
(degree of polymerization 500, degree of saponification 88 mol%) 5 parts of anchor and 2 parts of water (50 parts) in a completely enclosed mixer of the same type as in Example 2,
The mixture was mixed and kneaded in the same manner as in Example 2, and the kneaded product was poured into 20 parts of water and stirred to obtain an aqueous dispersion containing almost no air bubbles.

Example 5 100 parts of 2-polyvinyl acetate (degree of polymerization approximately 2500) and polyvinyl alcohol (Kuraray Poval #217, degree of polymerization 1700)
, degree of saponification 88 mol%) was kneaded for 30 minutes at 100°C in a completely closed kneader, 5 parts of water was added little by little, and kneading was continued for 1 hour. It was distributed in the mixing machine.

Then, the kneaded product was taken out from the kneader and poured into 10 g of water to give a stable aqueous dispersion containing almost no air bubbles. Example 6 Polystyrene (degree of polymerization about 2000) 10 anchors and polypinyl alcohol (degree of polymerization 600, degree of saponification 98 mol%) 5
Put the foundation and water 4 foundation in a completely closed type Tsuru kneading machine, knead at 160 oo for 1 hour while circulating steam, and put the kneaded material into 110 parts of water and shake it to remove most of the air bubbles. A stable aqueous dispersion was obtained.

Example 7 As a result of processing in the same manner as in Example 1, using atactic polypropylene 10 anchor parts instead of synthetic polyisoprene,
A stable aqueous dispersion containing almost no air bubbles was obtained.

For comparison, an aqueous dispersion was produced in the same manner except without blowing in steam, and an aqueous dispersion containing many fine bubbles was obtained. When this aqueous dispersion was allowed to stand for about 3 seconds, a large amount of bubbles rose to the surface of the liquid. Example 8 An aqueous dispersion was produced in the same manner as in Example 6 except that an ethylene-vinyl acetate copolymer 10 base having an ethylene content of 90 mol % was used instead of polystyrene.

Claims (1)

[Claims] 1. Polyvinyl alcohol resin or its hydrated material is added to water-insoluble thermoplastic resin or/and rubbery substance and kneaded, preferably water is added during kneading, and after kneading, the kneaded material is mixed with water as necessary. In producing an aqueous dispersion of the thermoplastic resin or/and rubber-like substance, the aqueous dispersion is characterized in that defoaming is carried out at least in the final stage of the kneading by kneading in a steam atmosphere. manufacturing method.