JPS60243127A - Method for drying polyester resin - Google Patents

Abstract

PURPOSE:To dry a polyester with saved time and energy without deteriorating the resin, by applying mechanical energy to a low crystalline polyester resin to heat the resin at a constant temperature, agglutinating mutually the resin, cooling the agglutinated resin, disintegrating the resin into a granular shape, and drying the resin. CONSTITUTION:A polyester resin having 0-5cal/g calorific value is dried. In the process, the above-mentioned polyester resin is subjected to stroking and/or stirring and heated to a temperature of the softening point or above and lower than the melting point of the crystal to agglutinate mutually the above-mentioned polyester resin. The resultant agglutinated polyester resin is then cooled to a temperature below the softening point thereof, disintegrated into a granular shape, and dried. The cooling is preferably carried out by adding a small amount of a refrigerant, e.g. water or an alcohol thereto. In the disintegration after the cooling, the granular shape is as follows; <=100mm., preferably <=20mm. and >=1mm., preferably >=3mm. length of the longest part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for drying a polyester resin having a crystallization calorific value of 0 to 5 cal/g or less, that is, a low crystallinity polyester resin.

[Prior art]

Conventionally, the drying method for low-crystalline polyester resin is as follows:
Pre-crystallization treatment by immersion in hot water or heating.

After pre-crystallization treatment in a container, 150-20
A method of main drying at 0°C is known.

[Disadvantages of conventional technology]

However, in such conventional methods, preliminary crystallization requires a long time, and the mutual fusion of resins generated during preliminary crystallization must be broken up in a separate step.

Deterioration of resin due to long thermal history and time.

The disadvantage was that there was a significant loss in energy consumption.

[Purpose of the invention]

The object of the present invention is to provide a method for drying polyester resin which does not have the above-mentioned drawbacks, that is, does not cause deterioration of the resin, takes only one hour, and causes less loss in terms of energy consumption.

[Structure of the invention]

The present invention has the following configuration to achieve the above object.

That is, when drying a polyester resin with a crystallization calorific value of 0 to 5 cal/g, the polyester resin is struck and/or stirred to raise the temperature to a temperature higher than the softening point and lower than the high melting point. A method for drying a polyester resin, which comprises: adhering polyester resins to each other, cooling the adhering polyester resin to a temperature below its softening point, crushing it into granules, and then drying the granular polyester resin. This is a characteristic feature.

The calorific value of crystallization applied to the present invention is O ~ 5 Cal/g
The polyester resin refers to one or more dicarboxylic acids or lower alkyl diesters thereof, and one
It is a polyester polymer obtained by condensation polymerization of a species or two or more diols by a conventional method, and specific examples include polyethylene terephthalate/isophthalate and polyethylene terephthalate/isophthalate/adipate.

Examples include polybutylene terephthalate/inphthalate, etc., and the calorific value due to crystallization of the resin during the heating process determined by differential thermal analysis (DSC) is 0 to 5 cal/g.
It refers to something.

However, the shape of polyester resin is not particularly limited; it can be powder, flake, or film.

The molded product may be of any shape as long as it is formed into a sheet, granule, etc., or may be a mixture of these. Particularly, when these starting materials are substantially amorphous or have a crystallinity of less than 10%, the effects of implementing the present invention are significant.

Hitting and stirring the polyester resin to raise the temperature to a temperature higher than the softening point and lower than the crystal melting point, and making the resins adhere to each other means applying so-called mechanical energy by hitting, cutting, and stirring the resin. Generate heat in the resin and raise the temperature of the resin to a temperature that is higher than the softening point of the resin (hereinafter referred to as T1) and lower than the crystal melting point (hereinafter referred to as T2).
It also allows the resins to adhere to each other.

In addition, in the present invention, when raising the resin temperature to T to T2, the resin may be heated with a known heating device as an auxiliary means for raising the temperature.

Here, the resin temperature refers to the temperature measured by a thermometer inserted into the resin in a device or container that applies mechanical energy.
Resin (granules) or.

Refers to a state in which multiple films or sheets are adhered and combined.

Further, the softening point of a resin is the temperature at which plastic deformation increases rapidly in a substantially amorphous state according to thermomechanical analysis, and sticking occurs at temperatures higher than this. Generally, the temperature is close to the glass softening point measured by differential thermal analysis.

The crystalline melting point of a resin is the temperature at which it becomes liquefied by increasing the temperature from a crystallized state, and is measured by differential thermal analysis from the exothermic peak when the crystals melt after successively increasing the temperature and crystallizing. .

Cooling the adhered polyester resin means lowering the temperature of the resin to a temperature below the softening point, preferably J30°C below the softening point.
Something that cools down to a low temperature.

Although the cooling method is not particularly limited, cooling by adding a small amount of liquid is preferable, and among liquids, water or alcohol-based refrigerants having a large latent heat of vaporization are more preferable.

Crushing the adhered polyester resin into granules means
The polymer is rapidly shrunk in volume due to cooling, and the coagulated polymer is crushed into granules by hitting or cutting. Although the size of one granule is not particularly limited, if the longest dimension of the granule is 100 mm or less, preferably 50 mm or less, and more preferably 20 mm or less, handling is good, which is '1'.

The drying process can be made more uniform. However, for ease of handling, the lower limit of the dimension of the longest part is 1Mn or more, preferably 3II]m or more.

``The cooling and crushing of the polyester resin described in item 2 may be performed at the same time as long as they are in the same device.

Although it may be crushed once cooled, the former is preferable.

Drying granular polyester resin 2 Well-known method 2
For example, it may be dried by any method such as vacuum drying or fluidized bed drying.

Note that the drying temperature is not particularly limited, but is 110 to 210
It is desirable to carry out the reaction at a temperature of 150 to 200°C.

Next, an example of the drying method of the present invention will be explained based on the drawings.

FIG. 1 is a schematic sectional view of an apparatus to which the method of the present invention is applied. FIG. 2 is a plan view of the device taken along the line AA' in FIG. 1.

In the figure, 1 is a device for adhering and crushing resin.

2 is a resin supply port provided at the top of the device 1, and 6 is the device 1.
4 is a fixed blade, 5 is a rotating blade, 6 is a motor for rotating 5, 7 is a thermometer for detecting the temperature of the resin, and 8 is a temperature indicator. By moving the two-rotary blade 5 up and down, the clearance with the fixed blade 4 can be adjusted to 1 to 10 mm.

To dry the resin, -1: While rotating the rotary blade 5 at high speed, the resin is intermittently or continuously supplied from the resin supply port 2. The supply amount is preferably about 50 to 80% of the device volume. The supplied resin rises due to shear heat generation and frictional heat generated between the single-rotation blade 5 and fixed blade 4, heat generated by collision between the device and the resin, and frictional heat generation due to mutual contact between the resins caused by the agitation of the double-rotation blade 5. The temperature is detected by the temperature measuring element 7 and displayed on the temperature indicator 8.

When the resin temperature is T, ~T2. Preferably 20-5 from T1
The rotary blade 5 continues to rotate until the temperature reaches a temperature 0°C higher.

When the resin temperature falls within the above range, the resin adheres, so the resin is cooled secondarily. It is preferable to maintain the resin temperature within the above range for 0.5 to 10 minutes, preferably 2 to 6 minutes, since the resin will not be uniformly adhered and crystallization will proceed sufficiently. Further, the temperature of the resin can be adjusted by changing the rotation speed of the single-rotation blade 5.

Cooling of the resin is not particularly limited, and may be performed by any method such as supplying gas or liquid into the apparatus 1, or transferring the resin to a bath liquid or the like.

A method of supplying gas or liquid into the device 1 is preferred.

When the adhered resin is cooled, it is crushed by the contraction force, and since the resin surface is cooled, agglomeration is inhibited, and the crushing is further promoted by the rotation of the blade 5 for one rotation, resulting in granules. becomes.

The granules thus obtained are dried using a known drying method.

[Action and effect of the invention]

As described above, the present invention uses a method of applying mechanical energy to polyester resin, raising the temperature to a specific temperature to cause it to coagulate, and then cooling, crushing, and drying.
The surface layer of the crushed resin undergoes significant crystallization in a short period of time, and even if the subsequent drying conditions for the resin are high, the resin does not fuse.

Further, it has the excellent effect of not causing deterioration due to heat.

[Measurement method of characteristic values]

The characteristic values of the present invention are determined by the following measurement method.

(1) Crystallization calorific value Dsc manufactured by PERKIN-ELMER
ential.

Scanning, Oalorimeter type 2 ÷
After melting 10 mg of the sample using a liquid nitrogen solution, the amount of heat generated is calculated from the exothermic peak accompanying crystallization when the temperature is increased at a temperature increase rate of 20° C./min after being rapidly cooled with liquid nitrogen.

(2) A spherical iron stand with a diameter of 2 mm at the softening point and a radius of 1 m at the tip, the weight of the rod is 20 g, and the temperature of the heating bath is 6°C.
The temperature was raised at a rate of 5 minutes, and the tips of the 4 rods were placed in the resin for 0.5 seconds.
n Refers to the temperature at the time of entry.

〔Example〕

Hereinafter, the present invention will be described in detail based on Examples. However, the present invention is not limited to this.

Example 1 In the device shown in Figure 1, the gap between the fixed blade and the rotating blade was set to 5 m.
m, and the number of revolutions of the blade was 1500 rpm. In this device, a chip (size 3 rrxn x 3 mm x 2 mm).

Gradually add an amount equivalent to 60% of the device volume.

The temperature was raised to 110°C and maintained at that temperature for 5 minutes.

Next, water was supplied into the apparatus 1 to cool the resin and crush it to obtain granules having the longest dimension of about 5 to 20 mm.

This granular material can be dried at 200°C, and no fusion between chips is observed even at this temperature.Moreover, the drying time can be shortened due to the high temperature, and no thermal deterioration of the resin is observed. Ta.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an apparatus for explaining the present invention in detail, and FIG. 2 is a sectional view taken along line A-A' in FIG. 1: Resin fusing/crushing device 2: Supply port 3: Output port 4: Fixed blade 5: Rotating blade 6: Motor 7: Temperature measuring element 8: Thermometer Patent applicant Azuma Shi Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (1) When drying a polyester resin with a crystallization calorific value of O to Scalh, the polyester resin is heated by hitting and/or stirring to a temperature higher than the softening point and lower than the crystal melting point, and the polyester resin is heated to a temperature higher than the softening point and lower than the crystal melting point. A method for drying a polyester resin, which comprises: coagulating the coagulated polyester resin, cooling the coagulated polyester resin to a temperature below its softening point, crushing it into granules, and then drying the granular polyester resin.