JPH0753729A - Preparation of photochromic dye-containing fine polyolefin resin powder - Google Patents

Abstract

PURPOSE:To prepare the powder improved in color development life by dissolving a polyolefin resin and a photochromic dye at a given wt. ratio in xylene, and then recovering the solvent with a vacuum dryer while at the same time obtaining the resulting particles in a dry state. CONSTITUTION:15-30 pts.wt. polyolefin resin, such as PE or PP, having a mol.wt. of 5,000 to 15,000, and 0.5-10wt.%, based on the resin, photochromic dye such as a spiropyran dye are added to and homogeneously dissolved in 100 pts.wt. xylene under stirring at a temp. of at most 110 deg.C. Thereafter, the temp. of the resulting soln. is dropped to at most about 80 deg.C. The soln. is then transferred to a vacuum dryer equipped with a stirrer, wherein it is dried under reduced pressure to simultaneously recover xylene. The resulting particles are pulverized with a jet pulverizer or the like to obtain a photochromic dye-contg. fine polyolefin resin powder having a particle size of at most 70mum and a color development life of 600 to 800hr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyolefin resin fine powder containing a photochromic dye.

[0002]

2. Description of the Related Art Various photochromic materials that are colored by ultraviolet rays and become colorless by visible light are known. The conventional coloring material products are simply kneading a coloring dye into a synthetic resin, and the life of coloring is about 10 to 40 hours, and it is only applied to specific articles regardless of its usefulness. Is.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a colorant-containing polyolefin resin fine powder that can be kneaded with a urethane or acrylic binder to form a printing ink, and the coloring material according to the present invention is a synthetic material. The present invention can be applied not only to resin molded products but also to textile products and other printable products to impart a photochromic effect for a long period of time. The photochromic dye to which the present invention is applicable is preferably a photochromic dye that is compatible with a polyolefin resin such as polyethylene or polypropylene, and for example, a spiropyran-based dye is suitable. According to the experience of the present inventor, when the polyolefin resin is heated and dissolved for the purpose of pulverization, it is most efficient to use a mixed solvent of xylene and methyl glycol 7: 3. It turned out to turn into. However, this material is not colorless by the sole solvent of xylene. On the other hand, when xylene is used as the solvent, the heat resistance temperature of the spiropyran dye is 120
Since it is ℃, it is necessary to completely dissolve the base resin in xylene at a temperature of 120 ° C. or less, and therefore it is necessary to use a low molecular weight polyolefin resin having a molecular weight of 5,000 to 15,000 that can be dissolved in xylene at a lower temperature. The particle size of 70 μm is required for making fine particles into ink, which is the final object of the present invention.
It is necessary to obtain the following particles in a high yield of 90% or more.

[0004]

The present invention has a molecular weight of 5,000 to 1
A method in which 5000 polyethylene or polypropylene resin and photochromic dye are dissolved in xylene at a temperature of 110 ° C. or lower, then lowered to a temperature at which liquid can be transferred and introduced into a solvent recovery tank, and colored particles are precipitated in the recovery tank. Is. For highly efficient recovery of particles of 70 μm or less, xylene and polyolefin resin are in a weight ratio of 100: 15 to 3
0, the ratio of photochromic dye to resin is 0.5
Although it is effective at more than 10% by weight, it is practically set to about 10% by weight because the dye is expensive. Also, the recovery of the precipitated particles requires that the dye is not dissolved in xylene, and that it must be obtained in a dry state at the same time as the solvent recovery in order to facilitate the handling of the recovered particles. To do. Therefore, it is not necessary to deposit the particles in the dissolution tank as in the usual dissolution method, and when the temperature reaches a temperature at which the solution can be transferred, the particles can be transferred to the recovery tank regardless of the precipitation state and particles can be generated by the above operation.

[0005]

[Effect] The colored powder of the present invention can be easily dispersed in a commercially available urethane or acrylic binder to form an ink, which can be applied to screen printing. Further, since the coloring dye is dissolved in the base resin and the resin powder itself is dyed, the coloring life of 600 to 800 hours, which is much longer than that of the conventional kneaded product, is maintained. The reason why the color development life of the product of the present invention is more than 10 times longer than that of the conventional color mixture-containing product has not been clarified at present.

[0006]

[Examples] 100 kg of xylene and polypropylene resin powder (SANYO KASEI “HIMER 330P” molecular weight 5,000 to 1500) were placed in a dissolution tank equipped with a stirring blade and a jacket.
0) 25 kg and 1 kg of spiropyran-based photochromic dye (“Sunny Color” (blue) manufactured by Recording Material) were added respectively, the temperature was 110 ° C., and the mixture was stirred for 1 hour to prepare a raw material solution. Then, the temperature was lowered to 70 ° C., and the mixture was transferred to a vacuum dryer with an agitator by an air pump (pressure ^{2 to 4} kgG / cm ² ) and dried under reduced pressure while maintaining the temperature at 60 ° C., and xylene was recovered. Since the particles in the machine are secondarily aggregated, they are crushed by a jet crusher or a rotary mechanical crusher. The particle size distribution was as shown in Table 1. In addition, the color system was changed to yellow, purple, violet, green and pink in addition to blue, but the same distribution was obtained. Further, a colored powder could be obtained under the same conditions even when the resin was polyethylene resin pellets.

[0007]

[Table 1]

As shown in the table, most of the particles were 32 μm or less. The colored particles were kneaded into a urethane or acrylic binder to form an ink, which was silk screen printed on a T-shirt. Although the color development due to the irradiation of the sun rays and the decolorization in the dark were reversed, no decrease in the color density was observed.
The coloring life of 0 hours or more was confirmed.

Claims (1)

[Claims] 1. A molecular weight of 5000 per 100 parts by weight of xylene.
15 to 30 parts by weight of a polyolefin resin of ˜15,000 and 0.5 to 10 wt% of the photochromic dye with respect to the amount of the resin are uniformly dissolved at a temperature of 110 ° C. or lower, and then the temperature is set to about 80 ° C. or lower to prepare the solution. Is placed in a vacuum dryer and solvent is recovered, and at the same time, produced particles having a particle size of 70 μm or less are obtained in a dry state.