JPH0245649B2 - HORIESUTERUJUSHIFUNMATSUNOSEIZOHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyester resin powder suitable for powder adhesives.

Polyester resin powders used in paints, adhesives, matting agents, etc. are usually pulverized by mechanical pulverization. On the other hand, a method of dissolving a polyester resin in benzyl alcohol and adding a precipitating agent to the solution to precipitate the polyester resin powder to obtain a powder (for example, Japanese Patent Application Laid-open No. 73452/1983), that is, chemical pulverization, is also known. ing.

In the chemical pulverization described above, when the polyester is heated and dissolved in benzyl alcohol, an ester conversion reaction between the benzyl alcohol and the polyester resin occurs and depolymerization occurs, so a decrease in the molecular weight of the polyester resin is unavoidable. Therefore, benzyl alcohol is unsuitable for the purpose of obtaining a fine powder that retains the molecular weight and properties of the original polyester resin.

However, as a result of extensive research into a method for producing polyester resin powder that solves the drawbacks caused by chemical pulverization, the inventors have discovered a good solvent for polyester resin (hereinafter simply referred to as "good solvent") and A polyester resin solution is prepared using a mixture of 10 to 80% by weight of a polyester resin as a poor solvent (hereinafter simply referred to as "poor solvent").
Next, they discovered the novel fact that if water is dispersed and then the good solvent is preferentially distilled off, a spherical polyester resin powder with no blocking properties and a sharp particle size distribution can be obtained, leading to the completion of the present invention. Ivy.

The constituent components of the polyester resin that are the object of the present invention include terephthalic acid, isophthalic acid, lower alkyl esters thereof, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, suberic acid, etc. as acid components. Examples of glycol components include ethylene glycol, 1.3-propanediol, 1.4-butanediol, 1.5-pentadiol, 1.6-hexanediol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, and neopentyl glycol.

Among these components, the acid components include (a) terephthalic acid or its ester, and (b) isophthalic acid (anhydride), phthalic acid, and aliphatic dicarboxylic acid.
(a):(b)=9:1 to 1:9 (molar ratio), and the glycol component is preferably one or more of the above glycol components. Furthermore, considering the adhesive performance as a powder adhesive among polyester resins consisting of these components, the crystallinity is about 15% (crystallinity: annealed at 80℃ for 2 hours). Polyesters up to X-ray diffraction measurements are preferred.

To carry out the present invention, it is first necessary to uniformly dissolve the polyester resin in a mixed solvent of a good solvent and a poor solvent. There are no particular restrictions on the dissolution method, including methods of dissolving polyester in a mixture of a good solvent and a poor solvent, methods of dissolving polyester resin in a good solvent and then adding a poor solvent, and methods of dissolving polyester in a mixture of a polyester resin and a poor solvent. A method of adding a solvent, a method of simultaneously mixing a polyester resin, a good solvent, a poor solvent, etc. can be implemented. A good solvent is
It must be inert to polyester resins and incompatible with water. Typical examples include chloroform (trichloromethane), methylene chloride (dichloromethane), dichloroethane, trichloroethane, trichloroethylene, halogenated hydrocarbons such as chlorobenzene, and benzene. Among these, dichloroethane and benzene are preferred.

On the other hand, the poor solvent must also be inert to the polyester resin and incompatible with water.
Examples include aliphatic alcohols having 4 or more carbon atoms such as n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, and n-hexane, n -heptane, n-octane,
Examples include aliphatic hydrocarbons having 6 or more carbon atoms.

In the above-mentioned mixed solvent of a good solvent and a poor solvent, the poor solvent must be used in a proportion of 10 to 80% by weight based on the good solvent. Only in the case of such a composition, it is possible to uniformly dissolve the polyester resin, and if the poor solvent is present in an amount of 80% by weight or more, a portion of the polyester resin will precipitate, so that only a polyester resin in aggregate form can be obtained. On the other hand, if the poor solvent is less than 10% by weight, it becomes lumpy and difficult to powder.

In the present invention, when a good solvent and a poor solvent are combined, it is necessary that the boiling point of the good solvent is lower than the boiling point of the poor solvent, and unless such a combination is used, the good solvent cannot be preferentially distilled off. A suitable boiling point difference is about 5°C or more. Furthermore, it is of course necessary to take care not to form an azeotrope so that the good solvent can be preferentially distilled off.

In the present invention, the polyester resin is stirred and dissolved in the mixed solvent at room temperature or under heating so that the concentration of the polyester resin is 10 to 55% by weight. When the concentration is 55% by weight or more, the particle size of the powder tends to increase and the particle size distribution tends to become broader. Water is then added to the solution while stirring. Since all the solvents used in the present invention have poor compatibility with water, they can be easily dispersed by adding water to the system and stirring. If the addition of water is omitted, ultrafine particles of 1μ or less are produced, and some of these particles increase during drying, resulting in a broad particle size distribution. The amount of water added is 100% by weight based on the good solvent.
Below, it is preferably selected from the range of 30 to 60% by weight.

Next, by preferentially distilling off the good solvent, polyester resin powder begins to precipitate.

By heating the above dispersion above the boiling point of the good solvent, the good solvent is gasified and distilled off.
The composition of the system gradually becomes excessive in poor solvent and water, and polyester resin powder begins to precipitate. By the time the good solvent is distilled off, the precipitation of the polyester resin powder is almost completed. Since the poor solvent and water remain in the system, there is no concern that the precipitated powder will cause blocking. After the precipitation is completed, solid-liquid separation is performed according to a conventional method, followed by heating and drying. Any dryer that is commonly used for drying powder may be used. At the precipitation stage or drying stage, known antiblocking agents, antioxidants, etc. which are usually added to powders can also be added. Furthermore, since the recovered solvent is easily separated from water, post-treatment such as distillation is not required and it can be reused as is.

In the present invention, the solution concentration of polyester resin, the ratio of good solvent to poor solvent, the type of solvent, temperature,
Although it varies depending on the stirring speed, etc., the obtained polyester resin powder has a particle size in the range of approximately 80 to 400 meshes, and is approximately spherical in shape and has a smooth texture. Therefore, it is particularly suitable as a powder adhesive, especially as a hot melt adhesive for textile fabrics.

Next, the present invention will be specifically explained with reference to Examples. In the examples, "parts" are "parts by weight" unless otherwise specified.

Example 1 150 parts of polyester resin (consisting of terephthalic acid, adipic acid, ethylene glycol, and diethylene glycol, crystallinity 3.5%) at 80°C
Dissolved in 350 parts of 1,2-dichloroethane. While stirring this solution at high speed, 170 parts of n-butyl alcohol and 300 parts of water were added at a constant rate at 25°C to obtain an oil-in-water type dispersion. This liquid was heated at 80°C under vacuum to drive out 1,2-dichloroethane. Eventually, powder began to form, and 1,2-dichloroethane continued to be sufficiently distilled off.
Subsequently, n-butyl alcohol and water were also distilled off, and the resulting wet powder was vacuum-dried in a dryer. As a result, polyester resin powder with an average particle size of 80 to 400 mesh was obtained. It was found that the powder having the above particle size had a yield of 85% by weight or more and had an extremely sharp particle size distribution. Further, no powder blocking was observed at all.

Example 2 80 parts of 150 parts of the polyester resin used in Example 1
It was dissolved in 350 parts of benzene at ℃. Further add n to the liquid
-120 parts of butyl alcohol and 200 parts of water were mixed. The mixture was vacuum distilled at 80°C to preferentially distill off benzene, and further n-butyl alcohol,
Water was also removed. When the wet powder is dried, the particle size is 80
~400 mesh polyester resin powder was obtained with a yield of 82% by weight. The particle size distribution was extremely good.

Comparative Examples 1 to 3 When the addition of water in Example 1 was omitted, the precipitated particles were in the form of ultrafine powder, and only 25% by weight of powder of 80 to 400 mesh was obtained.

Further, when 350 parts of n-butyl alcohol was used, only coarse particles with a particle size of 80 mesh or more were obtained.

Furthermore, when 10 parts of n-butyl alcohol was used, the mixture agglomerated and no powder was obtained.

Claims (1)

[Scope of Claims] 1. A polyester resin solution is prepared using a mixture of a good solvent for polyester resin and a poor solvent for polyester resin in an amount of 10 to 80% by weight based on the good solvent, and then water is dispersed. 1. A method for producing polyester resin powder, which comprises preferentially distilling off the good solvent. 2. Claim 1 in which the good solvent is a halogenated hydrocarbon or benzene, and the poor solvent is an alcohol having 4 or more carbon atoms or a hydrocarbon having 6 or more carbon atoms.
Manufacturing method described in section.