JPS6239621B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a vinyl chloride resin composition suitable for fluidized dipping. PVC resin is used in a wide range of applications due to its excellent mechanical properties, weather resistance, and chemical resistance, as well as its relatively low cost. Processability such as thermal stability, melt flowability, and powder flowability is required. PVC resin has excellent compatibility with plasticizers, so it is possible to obtain a wide range of products from soft to hard by changing the amount of plasticizer, but general-purpose vinyl chloride resins have excellent compatibility with plasticizers. The powder fluidity of the resin composition obtained by heating and mixing with a plasticizer at a temperature below the gelling temperature and cooling deteriorates in proportion to the amount of plasticizer, and as a result, the resin The composition coagulates and becomes solidified during storage, making it unusable for fluid dipping. On the other hand, in order to improve such drawbacks, the amount of plasticizer added may be reduced so that it is completely absorbed into the vinyl chloride resin, or a large amount of fine powder, such as a large amount of fine powder, may be added to the resin composition in which the plasticizer has been absorbed. There is a method of adding paste resin, silica, etc. and making it adhere to the surface of the vinyl chloride resin to prevent the stickiness of the plasticizer remaining on the surface of the vinyl chloride resin. However, simply reducing the amount of plasticizer added deteriorates the melt fluidity and impairs the appearance of the product after fluid immersion. Therefore, if the processing temperature is increased in order to obtain the same product appearance, the resin composition will thermally decompose and the mechanical and thermal properties of the product will deteriorate. In addition, when a large amount of fine powder is added to the resin composition, the adhesion of the fine powder to the vinyl chloride resin is weak, so if it continues to flow in the immersion layer for a long time, the fine powder and the vinyl chloride resin will be classified. As a result, the fine particles float to the upper layer of the fluidized bed, and the particle size distribution at the top and bottom becomes different, and because the amount of adhesion to the object to be coated differs depending on the size of the particles, the thickness becomes uneven between the top and bottom. This not only seriously impairs the appearance of the product, but also causes the fine powder to scatter during the flow, resulting in an adverse effect of deteriorating the working environment. The purpose of the present invention is to improve such conventional drawbacks,
It is an object of the present invention to provide a vinyl chloride resin composition having excellent properties for use in fluidized dipping. The vinyl chloride resin composition for fluidized dipping of the present invention (hereinafter referred to as the composition) has a micropore volume of 0.3 to 1.8cc/g and a macropore volume of 0.3 to 1.8cc/g.
20 to 100 parts by weight of plasticizer per 100 parts by weight of uniform spherical vinyl chloride resin powder having pores of 0.6 cc/g or less and a total pore volume of 0.85 cc/g or more. Features. More specifically, it is obtained by heating and mixing the resin and the plasticizer at a temperature below the gelation temperature and then cooling, and has a mesh throughput of 32. The vinyl chloride resin which is one component of the composition of the present invention has a micropore volume of 0.3 cc/g or more, preferably 0.4 cc/g or more, and usually 0.3 to 1.8 cc/g. It has pores with a macropore volume of 0.6cc/g or less, preferably 0.5cc/g or less, and a total pore volume of 0.85cc/g or more, and has a particle size of 32 mesh through and 500μ or less. It is a uniform spherical powder with no irregularities. Since the resin absorbs a large amount of plasticizer and has a high retention property after absorbing the plasticizer, the resin composition obtained by heating and mixing with the plasticizer and cooling it has good melt flowability, thermal stability, The powder has excellent fluidity. In particular, the macropores that exist between the irregularities on the particle surface tend to hold the plasticizer in the form of droplets, and the plasticizer easily leaches onto the particle surface. This tends to cause the fluidity to become extremely poor. It is preferable for the micropore volume to be as large as possible; the larger the value, the better the plasticizer retention, so once absorbed, the plasticizer will be less leached to the particle surface, and the fluidity will be greatly improved. . On the other hand, it is possible to produce a resin composition without any problems by increasing the blending temperature and lengthening the blending time, although the plasticizer absorption rate deteriorates. The total pore volume is
When the amount is less than 0.85 cc/g, the amount of plasticizer absorbed decreases, and the plasticizer remains on the particle surface, worsening fluidity. The vinyl chloride resin used in the composition of the present invention is not particularly limited by the polymerization method, such as suspension polymerization, bulk polymerization, suspension polymerization/emulsion polymerization, etc., but preferably suspension polymerization/emulsion polymerization. It is advantageous to use the method according to Japanese Patent Publication No. 49-2189 in combination. That is, vinyl chloride or a mixture with other vinyl monomers copolymerizable with vinyl chloride is first subjected to aqueous suspension polymerization using an oil-soluble radical initiator, and after 2 to 10 hours have elapsed from the start of the polymerization, water-soluble radicals are The vinyl chloride resin obtained by the method of continuing polymerization by adding an initiator has a molecular weight of 0.3 to 1.8 as exemplified in each example.
The vinyl chloride resin has pores with a micropore volume of cc/g, a macropore volume of 0.6 cc/g or less, and a total pore volume of 0.85 cc/g or more, and is preferably used in the present invention. The type of plasticizer, which is another component of the present invention, does not need to be particularly limited, and any known plasticizer can be used. For example, phthalate plasticizers, trimellitic acid plasticizers, aliphatic monobasic acid ester plasticizers, aliphatic dibasic acid ester plasticizers, aromatic ester plasticizers, hydroxy acid ester plasticizers, coal tar. Distillate plasticizers, epoxy plasticizers, phosphate esters, polyester plasticizers, etc. are used. The amount used is 20 to 100 parts by weight, preferably 25 to 40 parts by weight, per 100 parts by weight of the vinyl chloride resin. The amount of plasticizer used
If the amount is 20 parts by weight or less, the powder fluidity and powder cohesiveness will be extremely excellent, but the melt fluidity will deteriorate and the product appearance will be impaired. Therefore, in order to obtain the same product appearance, it is necessary to increase the processing temperature, which thermally decomposes the composition and thus deteriorates the mechanical and thermal properties of the product. If the amount of plasticizer used is 100 parts by weight or more, the melt fluidity will be extremely good, but the vinyl chloride resin will no longer be able to hold the plasticizer, and the powder fluidity will be extremely deteriorated, and the composition will agglomerate. until it solidifies. The vinyl chloride resin and plasticizer of the composition of the present invention can be easily mixed using a known mixer such as a Hensel mixer (trade name) or a ribbon blender. During mixing, in addition to various known stabilizers, various known processing aids for vinyl chloride resin compositions can be added within a range that does not impair the object of the present invention. The composition of the present invention is characterized by less plasticizer flowing out onto the particle surface, excellent powder fluidity and thermal stability, and the compositions do not aggregate together and do not solidify during storage. Furthermore, it has excellent melt fluidity and adheres uniformly to the object to be coated. Another advantage is that there is no scattering of fine powder during fluidized immersion, resulting in a good working environment. Since the composition of the present invention contains a larger amount of plasticizer in the vinyl chloride resin particles than conventional compositions, it has better melt flowability, which makes it possible to perform fluid dipping at a lower processing temperature. It is thought that thermal stability will be improved. Examples are shown below, but the present invention is not limited thereto. The properties of the vinyl chloride resin samples used in the Examples were tested in the following manner. Pore volume: Measured using a mercury intrusion porosimeter (model 70 manufactured by Carlo Erba), the volume of pores with a radius of 0.004 to less than 7.5μ is defined as the micropore volume, and the volume of pores with a radius of 7.5 to 75μ is defined as the macropore volume. show. Bulk specific gravity/particle size: Based on JIS K-6721. Amount of plasticizer retained: After immersing 100 g of PVC in DOP at 23°C for 1 hour and separating the DOP with a centrifuge (3000 rpm), it is expressed as the number of grams of DOP attached to the PVC. Plasticizer absorption rate: in a container immersed in a water bath at 80℃
Add 100g of PVC and 50g of DOP and mix while stirring.
It is expressed as the time it takes for the material to be absorbed into PVC and become smooth. Further, the composition of the present invention was tested using the following method. Powder fluidity: The composition was fluidized in a 290φ fluidized bed, and the degree of floating was observed and evaluated in 4 stages. ◎... High floating rate and no bubbling, 0... Low floating rate and no bubbling, △... Low floating rate and no bubbling, ×... No floating and bubbling, Powder coagulation property: Composition Fill a 25Kg paper bag and leave it for 30 days, then observe the solidification state and rate it in 4 stages. ◎...No coagulated material, ○... A small amount of coagulated material is present, △... A small amount of coagulated material is present, ×... A large amount of coagulated material is present. Surface smoothness: During the powder flowability test of the composition, a 50 x 100 x 3.2 mm iron plate was
The coating was heated to 300°C, immersed and coated, and the smoothness of the coated surface was observed and evaluated in 4 stages. ◎...Extremely smooth, 〇...Slightly uneven, △...
A little unevenness, ×...a lot of unevenness, Examples 1 to 4, Comparative Examples 1 to 2 128 kg of deionized water and 51.2 g of dilauroyl peroxide (LPO) as a radical initiator were placed in a stainless steel polymerization vessel with an internal volume of 200. , 51.2g of polyvinyl alcohol with a degree of saponification of 73% as a suspension stabilizer
After removing the air inside the vessel, 51.2 kg of vinyl chloride monomer was charged and polymerization was started at 64°C with stirring. 2.5 hours after the start of polymerization, 25.6 g of potassium persulfate (KPS) was injected as a 3% aqueous solution as a water-soluble radical initiator. After 8 hours (internal pressure 9.0Kg/
cm ² gauge pressure), polymerization was stopped, unreacted gas was discharged, and the resulting polymers were washed with water and dried to obtain vinyl chloride resin powder samples A, B, C, and D. As shown in Table 1, the stirring power was varied by changing the number of rotations of the paddle blades. For comparison, polymerization using an oil-soluble initiator alone was carried out. The difference from the above is KPS
The catalyst is not pressure-injected during polymerization, and LPO
After 7.5 hours, the polymerization was stopped when the internal pressure decreased to 9.0 kg/cm ² , and the same procedure as above was carried out to obtain vinyl chloride resin powder samples E and F. Table 1 shows the properties of these vinyl chloride resin powders. 20 kg of these vinyl chloride resin powder, 8 kg of dioctyl phthalate (DOP), 0.4 kg of dibutyltin dilaurate, 0.6 kg of dibutyltin mercapto,
Pour 1 kg of titanium oxide into 100 Hensel and heat to 120℃.
The mixture was heated to 100%, stirred, cooled, and passed through a 30-mesh sieve to obtain a composition. Table 1 shows the results of testing the composition according to a predetermined method.

【table】

[Table] Examples 5 to 8, Comparative Examples 3 to 4 Vinyl chloride resin was prepared in the same manner as in Example 1, except that the paddle-shaped impeller was changed to a blue margin-type impeller and the stirring power was as shown in Table 2. Powder G, H,
Samples I and J were obtained. In addition, as Comparative Examples 3 and 4, the same operations as in Comparative Examples 1 and 2 were performed except that the paddle-shaped impeller was changed to a blue margin-type impeller and the stirring power was as shown in Table 2. A sample of L was obtained. Table 2 shows these properties.
Shown below. A composition was obtained in the same manner as in Example 1 using these vinyl chloride resin powders. The test results are shown in Table 2.

【table】

[Table] Examples 9 to 11, Comparative Examples 5 to 6 Example 3 was carried out in the same manner as in Example 3 except that only the DOP amount of the composition was changed as shown in Table 3. The results are shown in Table 3.

【table】

Claims (1)

[Claims] 1. Micropore volume is 0.3 to 1.8 cc/g,
20 to 100 parts by weight of plasticizer per 100 parts by weight of uniform spherical vinyl chloride resin powder having pores with a macropore volume of 0.6 cc/g or less and a total pore volume of 0.85 cc/g or more. A vinyl chloride resin composition for fluidized dipping. 2. The composition according to claim 1, which is in the form of a powder with a 32-mesh through content.