JPH0592424A - Storing method for stamping molding material - Google Patents

Abstract

(57) [Summary] [Objective] To provide a rational method for storing stamping molding materials with a low water content. [Structure] The stamping molding material is stored in a storage that satisfies the following conditions. A ≦ 0.033 (0 <T <1) A · log (T + 1) ≦ 0.01 (1 ≦ T <10
0) A ≦ 0.005 (100 ≦ T) (A is absolute humidity (kg-steam / kg-dry air), and T is storage time (hour).)

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for storing a stamping molding material. More specifically, the present invention relates to a storage method in which the water content of the molding material is limited by the molding process in order to minimize deterioration of physical properties during the stamping molding process.

[0002]

2. Description of the Related Art Stamping molding is carried out by supplying a stamping molding material which has been melted by heating to a space between a pair of molds and rapidly applying pressure to shape it. In addition to having excellent material functions such that the forming method can be formed by an apparatus similar to the press forming method for steel sheets, and is lighter than steel sheets, and has corrosion resistance, etc. In addition, because of its high productivity, the ability to integrally form rib bosses, and the like, which leads to a reduction in the number of parts, great demand is expected for automobile parts, electric parts, miscellaneous goods parts, and the like. The stamping molding material used for stamping molding is obtained by impregnating and integrating a matte material made of long fibers with a thermoplastic resin by heating and pressing.

As the thermoplastic resin, polypropylene has been mainly used conventionally because it is lightweight and has heat resistance to some extent. However, polypropylene is not sufficient in the field requiring further excellent heat resistance and rigidity, and the use of high-performance resins in place of polypropylene is being investigated. Polyester resins such as polyethylene terephthalate (hereinafter abbreviated as PET) and polybutylene terephthalate (hereinafter abbreviated as PBT) and polyamide resins such as nylon 6 and nylon 66 have been studied as such high performance resins.
However, since these resins easily absorb moisture, it is necessary to control the water content of the molding material before stamping molding. Therefore, the practical use of these resins is currently delayed.

[0004]

In stamping molding of a molding material, it is necessary to heat and melt the molding material before supplying the molding material between a pair of molds. For example, P
To melt ET, it must be heated to about 300 ° C, but if there is a considerable amount of water in PET at this time, thermal decomposition due to water will occur during heating, and a molded product obtained by stamping molding Is brittle and cannot be obtained with satisfactory quality. Also in the case of a polyamide-based resin, hydrolysis due to moisture occurs during heating, the molded product obtained by stamping molding is brittle, and bubbles are easily formed in the molded product, and spray marks are easily formed on the surface of the molded product.

The water content of the stamping molding material immediately after production is about 200 ppm or less, but the water content varies depending on the atmosphere in which the molding material is stored before being subjected to stamping molding. Generally, when the stamping molding material is stored in the outside air, the water content in the molding material increases, but the water content of the molding material immediately before stamping molding depends on the hydrolyzability of the resin constituting the molding material, the stamping molding From the viewpoint of physical properties, etc., it is preferably about 500 ppm or less. As a method of keeping the water content of the molding material at about 500 ppm or less, a method of moisture-proof packaging of a stamping molding material immediately after production, a method of drying a hygroscopic stamping molding material, and the like are conceivable. (Japanese Patent Application No. 2-74999).

However, these methods require a great deal of cost for packaging and drying, and a more rational storage method in practical use is desired. The present invention aims to provide a rational method for storing stamping molding materials with a low water content of less than about 500 ppm.

[0007]

According to the present invention, the above object is achieved by storing the stamping molding material under the conditions represented by the following formula. A ≦ 0.033 (0 <T <1) − (1) A · log (T + 1) ≦ 0.01 (1 ≦ T <100) − (2) A ≦ 0.005 (100 ≦ T) − (3 ) (Where A is the absolute humidity of the storage atmosphere (kg-steam /
kg-dry air), and T indicates a storage time (hour). ) By storing the stamping molding material under such conditions, the water content of the molding material is maintained at about 500 ppm or less until just before stamping molding. The water content of the stamping molding material stored in this way is about 5
Since the content is maintained at 00 ppm or less, deterioration due to heat does not occur during stamping molding, and a molded product having excellent mechanical performance can be obtained.

In carrying out the present invention, use of a storage cabinet or a storage box to which dehumidified air is continuously supplied is mentioned as one of means for satisfying the above conditions, that is, one of means for reducing absolute humidity. Be done. Such a storage box or storage box is surrounded by an iron plate, a plastic plate, a veneer plate, etc. in an appropriate size, and is provided with only an entrance / exit for loading and unloading the molding material, and can be easily manufactured. Is. In the present invention, it is not limited to these storages and storage boxes, and any storage can be used as long as it can maintain an atmosphere satisfying the above conditions.

As the dehumidifying air, air compressed by a compressor and having a lower dew point can be used, but it is preferable to use an air having a dehumidifying air generator using a molecular sieve and having a dew point lowered to 1 ° C. or less. .. Also,
It is also possible to heat the dehumidified air and use the dehumidified heated air. The flow rate of dehumidified air or dehumidified heated air varies depending on the size of the storage box or storage box used. For example, when using a storage box or storage box having a size of 1 × 3 × 1.5 m, 10 to 1000 l / min. , Especially 2
It is preferably in the range of 0 to 100 l / min.

In the present invention, when the absolute humidity (kg-water vapor / kg-dry air) is 0.033, the corresponding relative humidity is as high as 70% at 40 ° C and 100% at 30 ° C. If the time is less than 1 hour, it may be stored in such an atmosphere. Absolute humidity (kg
-Water vapor / kg-dry air) is 0.01, the corresponding relative humidity is 22% at 40 ° C, 38% at 30 ° C, 70% at 20 ° C, the absolute humidity (kg-water vapor / kg-dry air) ) Is 0.005, the corresponding relative humidity is 11% at 40 ° C, 19% at 30 ° C and 35% at 20 ° C. The relative humidity (%) corresponding to the absolute humidity (kg-water vapor / kg-dry air) can be determined according to JIS Z8806.

In the present invention, the temperature of the atmosphere satisfying the above conditions depends on the storage location, but is preferably 130 ° C. or lower, and particularly 0 to 0 ° C. in order to prevent thermal deterioration of the thermoplastic resin constituting the stamping molding material. A range of 100 ° C is preferred.

In the present invention, it is desirable to store the stamping molding material in an atmosphere satisfying the above conditions from immediately after the production until the molding, but the molding material is temporarily not satisfied with the conditions such as transportation. Exposed under, about 5
Even when the water content exceeds 00 ppm, the water content of the molding material is lowered by storing it for several days in an atmosphere satisfying the above conditions, especially in an atmosphere satisfying the formula (3), A molded article having satisfactory mechanical performance can be obtained. The water content allowable amount in the stamping molding material in such a case is preferably 1000 ppm or less, and the stamping molding material having a water content of more than 1000 ppm can be stored in an atmosphere satisfying the above conditions for a long time. The water content of 1 is not preferable because it may not decrease so much that a molded product having practically satisfactory mechanical performance can be obtained.

As the resin used in the stamping molding material of the present invention, a polyester resin, a polyamide resin,
Examples of the resin include a resin having a structure that is easily hydrolyzed by water when heated, such as a polyurethane resin, but a polyester resin, particularly a PET resin is particularly preferable.

Examples of the polyester resin include polyesters mainly composed of alkylene terephthalate units, which contain terephthalic acid as a main acid component, ethylene glycol, tetramethylene glycol,
It is a polyester having a main glycol component such as cyclohexane-1,4-dimethanol, and may have a third component copolymerized therewith. The third component which can be copolymerized is diphthalic acid such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid, azelaic acid; trimesic acid, trimellitic acid. Acids, acids having polyfunctional ester forming ability such as pyromellitic acid; oxycarboxylic acids such as p-oxybenzoic acid and hydroxyethoxybenzoic acid; trimethylene glycol, hexamethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol Examples thereof include dihydroxy compounds such as; alcohols having a polyfunctional ester forming ability such as glycerin and trimethylolpropane.

Polyamide resin is a polymer having an amide bond, for example, nylon 6, nylon 66, nylon 1
0, nylon 11, nylon 12, nylon 610, polymetaxilelin adipamide, polymetaxylene sebacamide and the like.

The polyurethane resin is a thermoplastic polymer having a urethane bond, a urea bond, a buret bond, etc. in the repeating unit of the main chain and is obtained by a polyaddition reaction of diisocyanate and glycol. It is classified into ether type polyurethane, polyester type polyurethane and the like, and examples thereof include those generally used in the field of molding processing.

The long fiber reinforcing material used in the stamping molding material of the present invention includes inorganic fibers such as glass fiber and carbon fiber; organic fibers such as wholly aromatic polyester fiber, wholly aromatic polyamide fiber and polyvinyl alcohol fiber. Among them, glass fiber is economically suitable. These fibers are preferably treated with a treating agent such as a silane coupling agent in order to impart adhesiveness to the surface of the fibers.

The form of the fiber in the stamping molding material is not particularly limited, and strands cut into a certain length are dispersed in an indeterminate direction, continuous strands are bound by mechanical or chemical bonding. Alternatively, a mat-shaped material that is entangled with each other, a continuous strand that is aligned and aligned in a certain direction, or the like, or a combination thereof may be used. In addition,
A sizing agent containing a softening agent, an antistatic agent or the like may be applied to the strands in order to bundle the filaments. The content of the long fiber reinforcing material in the stamping molding material is preferably 10 to 70% by weight, particularly preferably 20 to 60% by weight.

In the stamping molding material used in the present invention, a peroxide decomposing agent, an antioxidant such as a radical scavenger, a colorant, an internal mold release agent, a lubricant, an antistatic agent, etc. are added to appropriately impart characteristics. It may be added.

[0020]

The stamping molding material using a resin such as a polyester resin, a polyamide resin, a polyurethane resin which is easily hydrolyzed by the presence of water at the time of heating is stored in a specific atmosphere to reduce the moisture content of the molding material. About 5
Since it can be maintained at 00 ppm or less, a molded product obtained by stamping molding the molding material has excellent mechanical performance without being subjected to thermal deterioration. Further, even if the water content of the stamping molding material exceeds about 500 ppm, the water content is lowered by storing it under the atmosphere of the present invention, particularly in the atmosphere satisfying the above formula (3), and it is practically used. A molded article having mechanically satisfactory mechanical performance can be obtained.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The physical properties of the stamping molding material were measured and evaluated by the following methods.

(1) Moisture content: Based on the Karl Fischer method, a trace moisture measuring device (CA-05 type, manufactured by Mitsubishi Kasei Co., Ltd.) and a moisture vaporizer (VA-05 type, manufactured by Mitsubishi Kasei Co., Ltd.) were used. It was measured using.

[Equation 1]

(2) Bending creaking sound: Distance between fulcrums is 16
200mm in length x 10 in width on the support stand set to 0mm
A 0 mm x 3 mm thick flat plate molded product was placed, and the presence or absence of a squeaking noise when a load to the extent that bending deformation (deflection) of the central part of this molded product to 6 mm was applied was judged.

(3) Intrinsic Viscosity [η]: Fragments of the stamping molding material are dissolved in a suitable solvent, the reinforcing fibers are filtered off to take out the polymer, and the polymer is mixed with tetrachloroethane-phenol by weight (PET). In the case of), the polymer concentration was changed and dissolved in dimethylformamide (in the case of polyurethane), the reduced viscosity of each concentration was determined, and it was determined from the relationship between the reduced viscosity and the concentration.

(4) Surface crack: A stamping-molded 200 × 100 × 3 mm flat plate molded product was subjected to 180 ° C.
After applying a thermal covering history in a hot air dryer for 5 hours, the plate was allowed to cool to room temperature, and the surface of the flat plate molded product was observed with the naked eye or a magnifying glass with a magnification of 5 times to see if cracks were generated (field of view of about 5 m.
m). Evaluation: No cracks observed with a magnifying glass ◎ (Extremely good) Some cracks observed with a magnifying glass ○ (Good) Cracks were observed on the whole surface with a magnifying glass ×

Examples 1 to 3 100 parts by weight of PET (KD236R, manufactured by Kuraray Co., Ltd.) having an [η] of 0.65, an antioxidant (Irganox 10)
0.3 part (manufactured by Ciba Geigy), 0.5 part of carbon black and 0.3 part of a release agent were mixed, kneaded at a cylinder temperature of 270 ° C. and extruded to obtain a sheet having a thickness of 800 μ. Then, two glass chopped strand mats (weight per unit area: 450 g / m ² , manufactured by Central Glass Fiber Co., Ltd.) and one sheet were alternately laminated so that the sheet was the outermost layer, and then a total of 10 sheets were laminated, and then 130 ° C. After being dried for 5 hours, it is impregnated and integrated by heating and pressing under the conditions of about 300 ° C., 3 kg / cm ² , and 3 minutes to obtain a stamping molding material having a glass fiber content of 40% by weight and a thickness of about 4 mm. .. This stamping molding material (300
X 200 mm) is an iron plate storage (1 x 3 x 1.5 m)
Stored in. The storage is 5k equipped with a dehumidifying air generator (Bolston, Johns Wire End Sons)
An air line of g / cm ² pressure is provided, and by supplying dehumidifying air having a dew point of −40 ° C. at a rate of 50 l / min, the absolute humidity (kg−water vapor / kg−dry air) is 0.005. It is maintained at (25 ° C, relative humidity 28%). After the storage time of 10 hours (Example 1), 100 hours (Example 2) and 1000 hours (Example 3), the molding material was taken out and the water content was measured. These stamping molding materials were cut into a size of 175 × 85 mm, heated to 310 ° C. to melt the PET, and then quickly pressed between a pair of molds having an internal size of 100 × 200 mm and kept at 160 ° C. By supplying and stamping molding, a flat plate molded product having a thickness of 3 mm was obtained. Table 1 shows the water content of the stamping molding material before molding and the evaluation results of the obtained molded product.

Example 4 and Comparative Example 1 A stamping molding material was obtained in the same manner as in Example 1, and the material had an absolute humidity (kg-steam / kg-dry air) of 0.0.
1 (30 ° C., 38% relative humidity) was stored in the same type of storage as in Example 1 (dehumidifying air having a dew point of −5 ° C. was supplied at a rate of 25 l / min). After the storage time of 5 hours (Example 4) and 100 hours (Comparative Example 1), the molding material was taken out and the water content was measured and found to be 450 ppm (Example 4) and 850 ppm (Comparative Example 1). These stamping molding materials were stamped and molded in the same manner as in Example 1 to obtain flat plate-shaped molded products. Table 1 shows the evaluation results of the obtained molded products.

Example 5 A stamping molding material was obtained in the same manner as in Example 1, and the material had an absolute humidity (kg-steam / kg-dry air) of 0.0.
It was stored in a simple box (1 × 1 × 1 m) of the FRP product kept at 08 (30 ° C., relative humidity 30%). An air cylinder is connected to the simple box, and air having a dew point of −10 ° C. is supplied into the box at a rate of 10 l / min. After storage for 10 hours, the material was taken out and the water content was measured to be 4
It was 00 ppm. This stamping molding material was stamped and molded in the same manner as in Example 1 to obtain a flat plate-shaped molded product. Table 1 shows the evaluation results of the obtained molded products.

Example 6 A stamping molding material was obtained in the same manner as in Example 1, and the material had an absolute humidity (kg-steam / kg-dry air) of 0.01.
It was left to stand in an atmosphere of 7 (30 ° C., relative humidity 65%) for 24 hours. The water content of the material was measured and found to be 750 ppm
Met. 10 of this material was stored in the storage container used in Example 1.
After storing for 0 hour, the product was taken out and the water content was measured and found to be reduced to 450 ppm. This stamping molding material was stamped and molded in the same manner as in Example 1 to obtain a flat plate-shaped molded product. Table 1 shows the evaluation results of the obtained molded products.

COMPARATIVE EXAMPLE 2 A stamping molding material was obtained in the same manner as in Example 1, and the material had an absolute humidity (kg-steam / kg-dry air) of 0.02.
It was stored in a simple box of the same type as in Example 5, which was kept at (30 ° C., relative humidity 77%). After storage for 7 hours, the water content of the material taken out was measured and found to be 800 ppm. This stamping molding material was stamped and molded in the same manner as in Example 1 to obtain a flat plate-shaped molded product. Table 1 shows the evaluation results of the obtained molded products. The performance was extremely inferior to the molded products obtained in the examples.

[0031]

[Table 1]

[0032]

As described above, by storing a stamping molding material using a resin which is easily hydrolyzed by the presence of water during heating under the atmosphere of the present invention, the water content of the molding material is about 500 ppm or less. The molded product obtained by stamping molding of such molding material has excellent performance. Further, if a stamping molding material having a water content of more than about 500 ppm is stored under the atmosphere of the present invention, the water content is reduced, and a molded product obtained by stamping molding the molding material has a practically satisfactory performance. Have.

[Brief description of drawings]

FIG. 1 shows a condition range defined in the present invention.

Claims (2)

[Claims] 1. A storage method comprising storing a stamping molding material under the following conditions. A ≦ 0.033 (0 <T <1) − (1) A · log (T + 1) ≦ 0.01 (1 ≦ T <100) − (2) A ≦ 0.005 (100 ≦ T) − (3 (However, A is the absolute humidity of the storage atmosphere (kg-water vapor /
kg-dry air), and T indicates a storage time (hour). ) 2. The storage method according to claim 1, wherein a storage cabinet to which dehumidified air is continuously supplied is used.