JPH0349303B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a lead silicate glass-based stabilizer for chlorine-containing coalescence, and more specifically, it has excellent dispersibility in chlorine-containing polymers and has a tendency to cause initial coloring of the polymers. The present invention relates to a lead silicate glass heat stabilizer which has a small amount of heat, has excellent thermal stability, and safely eliminates the foaming tendency of a blended resin composition. (Prior Art) It has been known for a long time that lead silicate has a thermal stabilizing effect on vinyl chloride resin and the like. Fused lead silicate (lead silicate glass), which is produced by reacting lead monoxide and silicic acid at high temperatures, has little reactivity, so it is of no use as a stabilizer for vinyl chloride, etc. (Refer to the left column of page 1 of the Japanese Patent Publication No. 32-757). Therefore, a method of manufacturing lead silicate as a stabilizer by a wet method, for example, a method of producing lead silicate as a stabilizer using a water-soluble lead salt such as lead acetate or lead nitrate, and silicate. Method of reacting with acid soda and silicate sol (Special Publication 1979-
No. 5668, No. 30-1872, No. 31-6840), and a method in which lead monoxide and silicate gel are reacted in water in the presence of a catalyst such as acetic acid if necessary (Japanese Patent Publication No. 32-
Publication No. 757) is known. (Problems to be Solved by the Invention) However, lead silicate produced by a wet process necessarily contains adsorbed water or hydrated water, and is mixed with a chlorine-containing polymer and subjected to thermoforming such as extrusion. When a molded resin product containing the resin is exposed to high temperatures, foaming of the resin occurs, which is a problem. If thermal stability could be imparted to lead silicate glass by some means, the aforementioned foaming problem could be solved, and it is expected that it would have excellent dispersibility in chlorine-containing polymers. . (Means for solving the problem) The present inventors have solved the problem by incorporating a lead oxide component in a highly reactive state into the lead silicate glass phase.
It has been found that unexpectedly excellent thermal stability against chlorine-containing polymers can be obtained for a fused silicate glass. In addition, since this heat stabilizer is a glassy substance formed by a melting method, it does not contain any decomposed and volatile components, nor does it have the ability to adsorb moisture, etc.
It was found that the foaming tendency was completely eliminated, and that it had excellent whiteness and excellent dispersibility in resin. According to the present invention, the lead component and the silicon component are
It consists of lead silicate glass powder containing a weight ratio of PbO:SiO2 = 70:30 to _90:10 , in particular 75:25 to 88:12, expressed as PbO and SiO2, respectively; It has the following particle size, and the following formula Rn=X1/X0×100 In the formula, X ₀ is the number of grams of lead oxide contained in 5 g of silicate glass, and X ₁ is the number of grams of lead oxide contained in 5 g of lead silicate glass. Silicic acid with a nitric acid reaction rate (Rn) of 30% or more and a Hunter whiteness of 80% or more, defined as the number of grams of lead oxide dissolved when stirred for 2 minutes in 50 ml of specified nitric acid. A stabilizer for chlorine-containing polymers is provided, characterized in that it is a lead glass powder. (Function) Although the lead silicate glass used in the present invention is obtained by melting and reacting lead oxide and silicon dioxide, it has a nitric acid reaction rate (Rn) of 30% or more, particularly 40% or more. is a notable feature. In this specification, nitric acid reaction rate has the following meaning. That is, in a given system containing lead oxide components and silicon dioxide components, if all of the lead oxide components exist in free form, the nitric acid reaction rate (Rn) will be 100.
Indicates the value in %. 0.35 normal nitric acid is of such acidity that it does not solubilize the lead oxide component bound in the form of lead silicate glass; thus, in the above system, if all of the lead oxide component is present in the form of lead silicate glass, nitric acid The reaction rate (Rn) shows a value of 0%. The fact that the lead silicate glass used in the present invention exhibits a nitric acid reaction rate of 30% or more means that 30% or more of the lead oxide component in the lead silicate glass composition is free lead oxide or close to free lead oxide. It means that it exists. Considering the formation stages of lead silicate glass in terms of time, the lead oxide component melts, silicon dioxide is dispersed in this molten continuous phase, silicon dioxide and molten lead oxide react on the surface of silicon dioxide particles, It is thought that lead silicate glass gradually forms in the glass phase, and eventually the glass phase becomes homogeneous throughout. The lead silicate glass used in the present invention is obtained at an intermediate stage in the above-mentioned lead silicate glass reaction process, and has a composition in which lead silicate, reactive glass components, and lead oxide components are mixed in the glass phase. It is clear that there are. The lead silicate glass powder used in the present invention has an excellent thermal stabilizing effect on chlorine-containing polymers by setting the nitric acid reaction rate (Rn) to 30% or more, particularly 40% or more. Table A below uses lead silicate glasses with different nitric acid reaction rates (Rn), and the following composition (based on weight - the same applies below): Vinyl chloride resin 100 parts Plasticizer 50 parts Lead silicate glass 5 parts Stearin Maturation stabilization time (molded article sample) for 0.3 parts of acid
(time until the sample turns black when placed in a gear oven at 210℃)
The test results are shown for the time it takes for Congo Red test paper to change color due to the generated hydrogen chloride when placed in an oil bath at ℃.

[Table] According to the results in Table A above, among lead silicate glass powders, those with a nitric acid reaction rate (Rn) of 30% or more,
It can be seen that it exhibits an unexpectedly excellent thermal stabilizing effect on vinyl chloride resin without changing the resin. Although the lead silicate glass used in the present invention contains free lead oxide, it has a small degree of coloring, and preferably has a Hunter whiteness of 80% or more, particularly 90% or more. Glasses in the range are excellent stabilizers for chlorine-containing polymers. Note that the whiteness of lead silicate glass depends on its raw material, melting temperature, and other factors. Thus,
This lead silicate glass has less tendency to stain chlorine-containing polymers. What is generally called an inorganic stabilizer has a tendency to color a chlorine-containing polymer slightly yellow to slightly red from the initial stage when it is blended into the chlorine-containing polymer. This initial coloring is thought to be due to the interaction between the chlorine-containing polymer and the inorganic stabilizer during melt-kneading. The lead silicate glass stabilizer used in the present invention has the advantage that it has a significantly lower initial coloring tendency than other lead-based stabilizers such as dibasic lead silicate as well as wet-process lead silicate. have In the lead silicate glass used in the present invention, PbO:
It is also important that SiO ₂ be present in a quantitative ratio of 70:30 to 90:10. That is, if PbO is less than the above range, a satisfactory thermal stabilizing effect cannot be obtained, and if it is more than the above range, it becomes difficult to vitrify as a homogeneous phase. This silicate glass should be a fine powder with a particle size of less than 10 μm, especially less than 7 μm, in terms of thermal stabilization and dispersibility in the resin. Although this lead silicate glass varies depending on its chemical composition, it generally has an oil absorption capacity of 6 to 30ml/100g (JIS K-5101-
19) and a bulk ratio of 1.7 to 2.3 g/cc, it is relatively dense and has a small amount of oil absorption, and is easily dispersed in resins and easily blended. (Description of structure) Lead silicate used in the present invention is obtained by melting and reacting lead oxide such as lead monoxide and lead sesquioxide with silicon dioxide so that the lead nitrate reaction rate (Rn) is within the above range. can get. The temperature and time for melting and reacting the lead oxide component and the silicon dioxide component vary considerably depending on the type of raw materials and the blending ratio of both components, and cannot be unconditionally defined. However, generally speaking, a temperature range of 600 to 1000°C, especially 700 to 950°C, and a period of 10 minutes to 60°C, especially
It is good to select conditions such that the above-mentioned nitric acid reaction rate (Rn) is in the range of 30 or more from the treatment time range of 15 to 45 minutes. The obtained molten reaction product is cooled by pouring it into water, etc., and granulated. The granules are pulverized dry or wet, classified if necessary,
A lead silicate glass stabilizer with a predetermined particle size. The lead silicate glass stabilizer used in the present invention has a plurality of crystal types; the first type is amorphous in terms of X-ray diffraction;
The X-ray diffraction image is shown in FIG. This amorphous type is obtained by dry grinding the cooled molten reactant. The second type has an X-ray diffraction image that substantially matches the following X-ray diffraction image plane spacing (Å) relative intensity ratio (%): . The X-ray diffraction image is shown in FIG. This X-ray diffraction image is
It is recognized to be unique to lead sesquioxide. The second type is obtained by wet milling of the cooled molten reactants. The reason why lead sesquioxide crystals are formed during wet milling is still unknown, but it is thought to be because free lead oxide components in the glass phase are oxidized and recrystallized during wet milling. Surprisingly, this type of material has excellent whiteness, with a Hunter whiteness of 80% or more, even though it contains lead sesquioxide crystals. In the third type, the lead silicate glass powder is substantially
It has an X-ray diffraction image that matches the line diffraction image area spacing (Å) and relative intensity ratio (%) 3.25 60 2.90 100 2.86 90. The X-ray diffraction image is shown in FIG. This X-ray diffraction image is recognized to be unique to lead pyrosilicate (Pb ₃ Si ₂ O ₇ ). The third type is obtained by treating the first and second types described above at the crystallization temperature of lead silicate, generally from 500 to 650°C. This type is slightly yellow,
It is a colored powder. The lead silicate glass used in the present invention is
Examples include other crystals such as PbSiO ₂ Pb ₂ SiO ₄ , mixed crystals of two or more of these types, or solid solutions of two or more of these types. Of course. The lead silicate stabilizer of the present invention has a significantly small specific surface area and oil absorption, so even if it is used alone, it can be easily kneaded into a chlorine-containing polymer resin.
It has excellent uniform dispersibility in resins, but if desired, the surface may be coated with various fatty acids, fatty acid soaps, fatty acid metal soaps, resin acid metal soaps, various waxes, and various resins. I can do it. Coating amount is 0.1 to 0.1 per lead silicate glass
A range of 10.0% is appropriate. Further, this coating layer can contain various organic stabilizers as stabilizing aids. Polyhydric alcohols, polyhydric phenols, and β-diketones are preferred;
Suitable examples thereof are mono- and dipentaerythritol, other polypentaerythritols, mannitol, sorbitol, glucose, fructose, trimethylolpropane, polyethylene glycol, polypropylene-polyoxyethylene block polymers, bisphenol A, sterically hindered phenols. , acetoacetate, acetylacetone, methylbenzoyl ketone, etc. In addition, examples of the chlorine-containing polymer used in the present invention include polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, chlorinated polypropylene, chlorinated rubber, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer coalescence, vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-isobutylene copolymer,
Vinyl chloride-vinylidene chloride copolymer, vinyl chloride-styrene-maleic anhydride terpolymer, vinyl chloride-styrene-acrylonitrile copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, chloride Vinyl-chlorinated propylene copolymer, vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, vinyl chloride-acrylic acid ester copolymer, vinyl chloride-maleic acid ester copolymer, vinyl chloride-methacrylic acid ester copolymer Polymers such as vinyl chloride-acrylonitrile copolymers, internally plasticized polyvinyl chloride, and these chlorine-containing polymers and α-olefin polymers such as polyethylene, polypropylene, polybutene, poly-3-methylbutene, etc., or ethylene. - Polyolefins such as vinyl acetate copolymers, ethylene-propylene copolymers and their copolymers, polystyrene, acrylic resins, copolymers of styrene and other monomers (e.g. maleic anhydride, butadiene, acrylonitrile, etc.) Examples include blends with acrylonitrile-butadiene-styrene copolymers, acrylic ester-butadiene-styrene copolymers, and methacrylic ester-butadiene-styrene copolymers. The chlorine-containing polymer composition of the present invention may also contain various additives known per se, such as plasticizers, antioxidants, light stabilizers, nucleating agents, fillers, nonmetallic stabilizers,
Organic tin, epoxy stabilizer, organic chelator, pigment,
Antistatic agent, basic inorganic acid salt, antifogging agent, plate-out prevention agent, surface treatment agent, lubricant, flame retardant, fluorescent agent, fungicide, fungicide, photodegrading agent, processing aid, mold release agent, etc. can be blended. (Operations and Effects of the Invention) According to the present invention, the dispersibility in chlorine-containing polymers is excellent, the tendency for initial coloring of the polymers is small, the thermal stability is excellent, and the foaming tendency of the blended resin composition is completely eliminated. A lead silicate glass heat stabilizer is provided. The invention is illustrated in the following examples. Example 1 In this example, a stabilizer for chlorine-containing polymers having a PbO:SiO ₂ ratio of 85:15 will be described. Lead oxide (PbO) raw material is LIS K- with the analysis value below.
1456, Resurge, a No. 1 approved product, was used. PbO 99.8% Loss on drying (105℃ x 3 hours) 0.05% Acetic acid insoluble content 0.05% Fe 0.0004% Cu 0.0001% In addition, as the silicon dioxide (SiO ₂ ) raw material, silica sand powder for crystal glass having the following analytical values and particle size was used. . SiO ₂ 99.9% K ₂ O 0.004% Na ₂ O 0.003% CaO 0.008% TiO ₂ 0.003% Al ₂ O ₃ 0.04% Fe ₂ O ₃ 0.002% Particle size 100Mesh on 2% 100Mesh~200Mesh 66% 200Mesh under 32% The above raw materials Dry mix PbO:SiO ₂ at a weight ratio of 85:15, and mix using an aluminum crucible at 950 °C.
The mixture was melted at ℃, and the melt was poured into water and quenched to obtain a cullet. This cullet was placed in a pot mill, and pure water was added thereto for wet pulverization, followed by dehydration and drying to obtain sample powder A. Further, the cullet was dried, taken in a pot mill, and dry-pulverized to obtain sample powder B. Further, sample powder A was calcined at 550°C to obtain sample powder C. Separately, the above melt was slowly cooled in a furnace to obtain a glass-like material, which was wet-pulverized to obtain a sample powder D, and dry-pulverized to obtain a sample powder E. Using these sample powders A to E, the following formulation was roll-kneaded and then pressed to produce a polyvinyl chloride sheet with a thickness of 1 mm. This sheet was tested for initial colorability, gear oven heat resistance at 210°C, and hydrogen chloride scavenging ability using the Congo Red method at 210°C. Polyvinyl chloride resin: 100 parts by weight Plasticizer: 50 parts by weight Sample powder 5 Part by weight Stearic acid 0.3 part by weight Table 1 shows the powder characteristics of the obtained sample powder and the test results of the polyvinyl chloride sheet.

【table】

[Table] Example 2 In this example, stabilizers for chlorine-containing polymers in which the weight ratio of PbO:SiO ₂ is varied will be described. A sample powder having a PbO:SiO ₂ weight ratio shown in Table 2 was obtained in the same manner as the sample powder A of Example 1. Next, a polyvinyl chloride sheet was prepared using the same formulation as in Example 1, and the same test was conducted. The results are shown in Table 2.

[Table] From Table 2 above, the PbO:SiO ₂ weight ratio is 70:30.
If the PbO content is less than that, there will be a shortage of heat stabilizer,
It is also understood that when the ratio of PbO:SiO ₂ is about 90:10, although it has a hydrogen chloride scavenging effect and a thermal stabilizing effect, the polyvinyl chloride changes drastically and becomes an unsuitable substance as a stabilizer.

[Brief explanation of drawings]

Figure 1 shows the X-
Figure 2 is an X-ray diffraction diagram of a wet-milled lead silicate glass stabilizer, and Figure 3 is an X-ray diffraction diagram of a heat-treated lead silicate glass stabilizer.

Claims (1)

[Claims] 1. The lead component and the silicon component are PbO and PbO, respectively.
The lead silicate glass powder is expressed as SiO2 and contains PbO:SiO2 in a weight ratio of 70:30 to 90:10, and is obtained by melting and reacting them. It has a particle size of 10 μm or less, and has the following formula: Rn=X1/X0×100, where X0 is the number of grams of lead oxide contained in 5 g of lead silicate glass, and The nitric acid reaction rate (Rn), defined as the number of grams of lead oxide dissolved when stirred for 20 minutes in 50 ml of 0.35 normal nitric acid, is 30% or more, and the Hunter whiteness is 80% or more. A stabilizer for chlorine-containing polymers, characterized in that it is a lead silicate glass powder. 2. The stabilizer according to claim 1, wherein the lead silicate glass powder is amorphous in terms of X-ray diffraction. 3 Lead silicate glass powder has an X-ray diffraction image that substantially matches the following X-ray diffraction image plane spacing (Å) relative intensity ratio (%) The stabilizer according to claim 1, which is 4. Claims in which the lead silicate glass powder has an X-ray diffraction image that substantially matches the following X-ray diffraction image plane spacing (Å) relative intensity ratio (%) Stabilizer according to paragraph 1.