JPH038385B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a soft sheet that is highly filled with a ferrite compound and has excellent forming processability and surface condition. In recent years, soft sheets filled with large amounts of ferrite compounds have been developed with excellent shapeability and processability.
Due to its workability, it is used in sound insulation sheets, magnets, semiconductive sheets, etc. These fields have recently become a hot topic, and demand is expected to steadily increase in the future. These soft sheets are
In most cases, a soft polymer base material is filled with a high-density substance for sound insulation sheets, a magnetic material for magnets, and fine powder of metal or metal oxide for semiconductive sheets. Among these filling materials, various ferrites in particular are used in extremely large quantities because they can be conveniently used for all of the above three types of uses. Among ferrites, recovered ferrite compound powder, which is a by-product during the production process of magnetic iron oxide, titanium oxide, etc., is inexpensive and suitable as such a filler. However, when polyvinyl chloride is filled with a large amount of the ferrite compound obtained in this way and kneaded with a roll, plate-out (sheet components including the filler adhere to the roll surface) occurs on the roll surface. . If calendering is performed in this condition, some of the sheet components will adhere from the sheet surface to the roll surface, causing the sheet surface to become dirty, and if this phenomenon progresses further, a large amount of sheet components will adhere to the roll surface. It becomes impossible to continue calendar processing. The cause of this is not clear, but it is believed that the recovered ferrite compound contains a considerable amount of impurities, including heavy metals other than ordinary iron, which reduces its compatibility with polyvinyl chloride and plasticizers. Presumed. As a result of repeated studies in order to develop a soft sheet free from the above-mentioned drawbacks found in a mixed system of polyvinyl chloride, a plasticizer, and recovered ferrite compound powder, the present inventor found that polyvinyl chloride 10 to 90 with a degree of polymerization of 2000 or more parts by weight and 90 to 10 parts by weight of polyvinyl chloride with a degree of polymerization of 1200 or less for a total of 100 parts by weight of resin,
A composition containing 50 to 120 parts by weight of a plasticizer, 1 to 10 parts by weight of a stabilizer, and 150 to 800 parts by weight of recovered ferrite compound powder has excellent moldability and surface condition, and can be continuously processed by calendar processing. We have discovered that it can be produced, and have arrived at the present invention. In other words, if polyvinyl chloride with a polymerization degree of 2000 or more and polyvinyl chloride with a polymerization degree of 1200 or less are blended and the polymerization degree is set to 1500, for example, when processed using such a blend resin, a molecular weight distribution with a simple single peak will result. It has much better workability than calender processing using resin with a polymerization degree of 1500. Even if such a blended resin is filled with a large amount of recovered ferrite and rolled, it does not plate out on the roll surface unlike conventional methods, and the sheet strength during processing is sufficient, so it can be produced continuously by calendar processing. The surface condition of the obtained sheet is extremely excellent. On the other hand, when polyvinyl chloride with a degree of polymerization of 1500 and a simple single-peak molecular weight distribution is used, plate-out is severe during roll processing, and even if a sheet is obtained, the surface of the sheet is dirty and very Not suitable for practical use. Further, the sheet strength during processing is not sufficient. The polyvinyl chloride used in the present invention includes vinyl chloride homopolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, and vinyl chloride-ethylene-vinyl acetate copolymer graft polymerized with vinyl chloride. Examples include vinyl chloride copolymers such as vinyl chloride copolymers. Those with a high degree of polymerization preferably use up to 4000, and those with a low degree of polymerization preferably use up to 500. As the plasticizer added to polyvinyl chloride, ordinary ones can be used. The amount is 50~
120 parts by weight is desirable; if it is less than 50 parts by weight, the purpose of softening will not be achieved, and if it is more than 120 parts by weight, the strength will decrease. As the stabilizer, a usual stabilizer added to polyvinyl chloride can be added. The amount added is 1
Parts by weight to 10 parts by weight are preferable, and even if more than 10 parts by weight are added, no further effect can be expected, and if it is less than 1 part by weight, no effect as a stabilizer is expressed. The recovered ferrite compounds used in the present invention include ferrite compounds generated in the ferrite method for removing harmful heavy metals from industrial waste, or recovered ferrite compound powders produced as by-products in the production process of magnetic iron oxide, titanium oxide, etc. etc. The components of such recovered ferrite compounds are:
Contains magnetite (Fe ₃ O ₄ ), iron oxyhydroxide (FeOOH), and iron trioxide (Fe ₂ O ₃ C), as well as trace amounts of other heavy metals and impurities. The particle size of these ferrite compound powders depends on the physical properties of the sheet,
Considering the surface properties, etc., it is desirable that the thickness be 150 mesh or less. Moreover, the amount is preferably 150 parts by weight to 800 parts by weight. If it is less than 150 parts by weight, the effect of ferrite will not be fully expressed, and if it is more than 800 parts by weight, calendering will be difficult and various physical properties as a soft sheet will deteriorate. However, if there are no particular concerns about physical properties, it is possible to fill even 1000 parts by weight of recovered ferrite compound powder with respect to 100 parts by weight of polyvinyl chloride. In addition, it is also possible to add not only such recovered ferrite compounds but also general fillers that have low compatibility with resins and plasticizers. Furthermore, a phosphate ester surfactant may be added to improve processability. The various components used in the present invention may be mixed by stirring and kneading using various mixers such as a Henschel mixer or a ribbon blender, or by using a Banbury, roll, or the like. The obtained mixture can be molded using an extrusion molding machine or a calendar molding machine. It is also possible to perform processing such as printing, painting, plating, etc. on the surface of the sheet as desired. Applications of the soft sheet of the present invention include sound insulating sheets, magnetic sheets, semiconductive sheets, antistatic sheets, and electromagnetic shielding sheets. The present invention will be explained below with reference to Examples. Examples 1 to 3, Comparative Examples 1 to 2 Each component was added to 160% according to the formulation shown in Table 1.
The mixture was kneaded for about 10 minutes using a mixing roll heated to 170°C and calendered. The final sheet thickness was adjusted to 0.5 mm. The evaluation results of the obtained compound by roll kneading and calendering are as follows.

[Table] Example 1 There was no plateout at all, and the 0.5 mm sheet had sufficient strength at 155°C. The surface condition of the obtained sheet was extremely clean with no uneven parts. The peelability of the sheet from the roll at 160°C was also good. Example 2 There was no plateout at all, and the 0.5 mm sheet had sufficient strength at 155° C., and the bank rotation was also good. The surface condition of the obtained sheet was extremely clean with no uneven parts. 160℃
The peelability of the sheet from the roll was also good. Example 3 There was no plate-out and the 0.5 mm sheet had sufficient strength at 155°C. However, the sheet was slightly softer than Inventive Example 1 and had better bank rotation. The surface condition of the obtained sheet was extremely clean with no uneven parts. The peelability of the sheet from the roll at 160°C was also good. Comparative Example 1 The 0.5 mm sheet at 155°C had some strength, but plate-out was noticeable. The surface condition of the obtained sheet is not uniform, and cold marks (a part of the molten mixture has a hard part at a low temperature, so the rolled sheet has rough streaks and hard parts resembling bird footprints). ) are noticeable. 160
Peeling of the sheet from the roll at .degree. C. was possible. Comparative Example 2 The sheet strength of 0.5 mm at 155°C was not sufficient and plate-out was quite noticeable. The surface condition of the obtained sheet was not uniform, and the cold marks were quite noticeable and the sheet surface was dirty. 160
The peelability of the sheet from the roll surface at ℃ was not good.

Claims (1)

[Claims] 1 Blend 10 to 90 parts by weight of polyvinyl chloride with a degree of polymerization of 2000 or more and 90 to 10 parts by weight of polyvinyl chloride with a degree of polymerization of 1200 or less, and make a blend of 100 parts by weight as the total amount of resin.
A soft sheet containing 50 to 120 parts by weight of a plasticizer, 1 to 10 parts by weight of a stabilizer, and 150 to 800 parts by weight of recovered ferrite compound powder.