JPH0247487B2 - HORIESUTERUFUNMATSUNOSEIZOHOHO - Google Patents

Description

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

Polyester powder used in paints, adhesives, matting agents, etc. is usually pulverized by mechanical pulverization. On the other hand, a method of obtaining polyester powder by dissolving polyester in benzyl alcohol and adding a diluent to precipitate the polyester powder (Japanese Unexamined Patent Publication No. 73452/1989), that is, chemical pulverization, is also known. .

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 occurs and depolymerization occurs, so a decrease in the molecular weight of the polyester 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.

However, the present applicant previously filed an application regarding a method for producing polyester powder that solved the drawbacks caused by chemical pulverization, but upon further investigation, the present inventors found that polyester with a crystallinity of 15% or less and 1. The solvent is inert to the polyester and has a solubility parameter of 8 to 12.5; 2 The precipitating agent is a lower aliphatic alcohol, a lower aliphatic ester of the alcohol, a ketone or an ether; 3 Furthermore, the solvent and precipitant can only be turned into fine powder by chemically grinding them with a solvent and precipitant that satisfy the conditions 1) to 3) above, that the boiling point of the solvent is lower than the boiling point of the precipitant. The present inventors have discovered that a polyester powder having excellent powder characteristics, which has no blocking property and whose fine powder has a substantially spherical shape, can be obtained, and has completed the present invention.

The constituent components of the polyester in the present invention include terephthalic acid, isophthalic acid,
These lower alkyl esters, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid,
Examples include suberic acid, and glycol components include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, and cyclohexanedimethanol. , neopentyl glycol, etc.

Among these components, the acid components are (a) terephthalic acid or its ester and (b) isophthalic acid, (anhydrous) 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. Among polyesters composed of these components, considering the adhesive performance as a powder adhesive, polyesters with a crystallinity of 15% or less (crystallinity: polyester annealed at 80℃ for 2 hours) X-ray diffraction measurement) is suitable.

Next, the polyester solvent in the present invention must be inert to the polyester.
And also the solvent has a solubility parameter of 8
Must be ~12.5. Solvents with solubility parameters outside this range are undesirable because the polyester becomes difficult to dissolve, but they are not completely unsuitable for use.

Examples of solvents include benzene, chlorobenzene, chloroform (trichloromethane), methylene chloride (dichloromethane) dichloroethane, trichloroethane, 1,4-dioxane, tetrahydrofuran, pyridine, dimethylformamide, etc. Among these, methylene chloride, chloroform, - 4-dioxane etc. are preferred.

The precipitating agent is a lower aliphatic alcohol, a lower fatty acid ester of the alcohol, a ketone or an ether. If anything other than these is used as a precipitating agent, the precipitated resin will stick together, resulting in disadvantages such as not being able to obtain fine powder, not having uniform particle sizes, and not being able to obtain good flow characteristics, which is not desirable. . As a lower aliphatic alcohol,
Examples include methanol, ethanol, propanol, butanol, and each can be used alone. Examples of the lower fatty acid ester of the alcohol include acetate esters such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate, formate esters, propionate esters, butyrate esters, and the like, which are used in combination with the alcohol. Powder properties such as particle size and fluidity can be adjusted as desired by using them in combination. The ratio is alcohol/ester = 1/9 to 9/1
(weight ratio). Ketones include acetone,
Examples include methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, diethyl ketone, cyclohexanone, and acetophenone, which are also used in combination with alcohol. Powder properties such as particle size and fluidity can be adjusted as desired by using them in combination. The ratio is alcohol/ketone = 1/9 to 9/1
(weight ratio).

Examples of the ether include diethyl ether, isopropyl ether, and ethylene glycol diethyl ether, which can be used in the same manner as lower fatty acid esters and ketones. The ratio is alcohol/ether = 1/9 to 9/1 (weight ratio)
It is.

In the present invention, in addition to using the above-mentioned polyester solvent and precipitating agent, these solvents and precipitating agents must satisfy the following condition: boiling point of the solvent<boiling point of the precipitating agent. When recovering polyester precipitated by adding a precipitating agent to a polyester solvent solution, the solvent and precipitating agent are gasified and expelled from the system. At higher temperatures, the liquid composition in the system becomes increasingly solvent-rich during the expulsion step. The precipitated polyester particles are therefore redissolved in this solvent and become sticky and stuck. If this method were to prevent sticking, the polyester would precipitate, then undergo solid-liquid separation, and the wet cake would be further washed with a precipitating agent.
The cake may be dried after replacing the solvent in the cake with a precipitating agent. However, such a method cannot avoid the economic disadvantage of having to replace the solvent with a precipitating agent and recovering a large amount of the used precipitating agent.

However, if a solvent with a boiling point lower than that of the precipitating agent is used, the liquid composition in the system will gradually become excessive in the precipitating agent during the expulsion and drying process of these precipitating agents and solvents. The particles do not stick at all, and the polyester powder has a soft texture. If the boiling point difference between the precipitating agent and the solvent is approximately 5° C. or more, the resulting polyester powder will have good particle size and fluidity. Furthermore, by adjusting the proportion of alcohol and ester, alcohol and ketone, or alcohol and ether used as precipitants as described above, powders with excellent particle size, fluidity, and other powder properties can be obtained as desired.

In the present invention, polyester is stirred and dissolved in the solvent at room temperature or under heating to a concentration of 10 to 25% by weight. When the concentration is 30% by weight or more, the particle size of the powder tends to increase and the particle size distribution tends to become broader. Next, while stirring this solution at high speed, a precipitating agent is added at a constant rate or intermittently. The amount of precipitating agent added depends on the amount of dissolved polyester.
A target of 98% or more precipitation is set as appropriate. The required amount of the precipitating agent may be charged all at once or dividedly. In the latter case, for example, first add a small amount of precipitating agent to the polyester solution to prevent powder precipitation, then distill off a portion of the solvent and add the remaining precipitating agent to precipitate the powder, which will result in a uniform particle size. The product has advantages. To recover the polyester powder, the obtained slurry is directly heated and dried. Alternatively, any method may be used in which the slurry is separated into solid and liquid and then heated and dried. 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.

In the present invention, the polyester solution concentration,
Although it varies depending on the ratio of solvent and precipitating agent, type of precipitating agent, temperature, stirring speed, etc., the obtained polyester powder is a fine powder in the range of approximately 150 to 500 meshes, and is almost spherical in shape with a smooth texture. belongs to. 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 20 parts of polyester (consisting of terephthalic acid, adipic acid, ethylene glycol, and diethylene glycol, crystallinity 3.5%) was dissolved in 80 parts of methylene chloride. While stirring this solution at high speed,
100 parts of methanol was added at full speed at ℃, and the polyester was precipitated. Next, this was heated under reduced pressure to evaporate and remove the solvent and precipitating agent to obtain a polyester powder. The obtained powder contained 85% by weight of 200 to 400 meshes and was approximately spherical.

Example 2 To 100 parts of the polyester methylene chloride solution,
While stirring at high speed, a mixed solvent of 60 parts of methyl acetate and 50 parts of methanol was added at a constant rate at 25°C to precipitate the polyester. Next, the solvent and precipitant were removed by distillation to obtain polyester powder. The obtained powder had 91% by weight of 200 to 500 meshes and was approximately spherical.

Control Example 1 20 parts of the above polyester were dissolved in 80 parts of dioxane. 80 parts of methanol was gradually added to this solvent under stirring at 25°C, and the mixture was allowed to stand and the wet polyester obtained by solid-liquid separation was dried at 80°C. ~400 meshes accounted for 45%.

Control Example 2 To 100 parts of the polyester dioxane solution of Control Example 1, 120 parts of toluene was gradually added with stirring. The solvent and precipitant were then distilled off and dried, and the resulting powder had a wide particle size distribution, with only 52% of the powder having a mesh size of 200 to 400.

Example 3 30 parts of the polyester used in Example 1 was dissolved in 70 parts of methylene chloride. Add this solution to 40 °C under stirring.
Then 13 parts of methanol was added. Next, after heating to distill off 48 parts of methylene chloride, 26 parts of methanol was further added to precipitate polyester powder. Subsequently, methylene chloride and methanol were removed by evaporation to obtain polyester powder.

The obtained powder had 80% by weight of 300 to 400 meshes and was approximately spherical.

Claims (1)

[Claims] 1. When adding a precipitating agent to a polyester solvent solution to precipitate polyester to obtain polyester powder, 1. a polyester having a crystallinity of 15% or less and 1. a solvent that is inert to the polyester and capable of dissolving the polyester; 2. The precipitating agent is a lower aliphatic alcohol, a lower fatty acid ester of the alcohol, a ketone or an ether; 3. The solvent and the precipitating agent should be selected such that the boiling point of the solvent is higher than that of the precipitating agent. A method for producing polyester powder, characterized by using a solvent and a precipitating agent that satisfy conditions 1) to 3) below the boiling point.