JPH0530606B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a molded article of a metal salt of polyacrylate. Specifically, the present invention relates to a method of filling metal salt powder into a mold and then press-molding it at a pressure of 100 kg/cm ² or more to form a molded body. The metal salt polymer molded product obtained by the method of the present invention has high heat resistance and compressive elastic modulus, and is useful as gears, aircraft materials, architectural structural materials, and electronic/electrical materials. [Prior art] The method for molding polyacrylic acid metal salts involves heating and melting a mixed powder of polyacrylic acid powder and divalent metal oxide in a mold to generate polyacrylic acid metal salts, which are then pressurized. A method of molding is known.
However, with this method, the releasability of the molded product is poor, and the molded product obtained is likely to crack or crack. The present inventor has previously proposed a method to eliminate such drawbacks and obtain a molded article with good mold release properties, high strength, and high modulus of elasticity by press-molding powder of metal salt of polyacrylate. (Unexamined Japanese Patent Publication No. 1983-74905, 74906,
259818 publications). [Problems to be Solved by the Invention] By the above method, molded bodies of any shape having a high flexural modulus can be obtained, but their heat resistance is around 200°C. The present invention aims to provide a method for producing a molded product of polyacrylic acid metal salt having high strength and high modulus of elasticity, and which also has higher heat resistance. [Specific Means for Solving the Problems] That is, the present invention provides a method for forming a molded body by pressure-molding a polyacrylic acid metal salt powder in a mold at a pressure of 100 kg/cm ² or more. Before pressure molding
The present invention provides a method for producing a molded product of metal polyacrylic acid salt, which is characterized by heat treatment at 150 to 500°C. (Polyacrylic acid metal salt) Polyacrylic acid metal salt is produced by, for example, mixing polyacrylic acid and a metal compound in an aqueous alkali metal hydroxide solution such that the amount of metal ions is 0.1 to 20 equivalents per equivalent of the acidic group of the polymer. Obtained by reacting with Polyacrylic acid is 80-100 mol% acrylic acid
and 20 to 0% of other vinyl monomers are copolymerized or polymerized. The degree of polymerization of this polymer is 50 to 1,000,000, and in order to make the molded product high in strength, the higher the degree of polymerization, the better.
It is preferably 100 or more, and 50,000 or less is preferable because the smaller the polymerization degree of the polymer solution used in the production of the metal salt polymer, the lower the viscosity and the easier handling. Metal ions include Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ ,
Cs ⁺ , Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , La ³⁺ ,
Ti ⁴⁺ , Cr ³⁺ , Mn ²⁺ , Fe ²⁺ , Fe ³⁺ , Co ²⁺ , Ni ²⁺ ,
Cu ⁺ , Zn ²⁺ , Al ³⁺ , Sn ⁴⁺ , Pb ²⁺ etc. can be used.
These may be used in combination. After the reaction, the precipitated metal salt polymer is filtered to separate the solvent, and then washed to remove unreacted materials and
By-products are removed, then dried and, if necessary, ground to form a powder of 0.01 to 500 microns, which is used as a molding material. In order to obtain a dense molded product, the smaller the particle size, the better, so the particle size is preferably 200 microns or less, and in terms of handling, the larger the particle size, the easier it is, so the particle size is preferably 0.1 micron or more. (Heat treatment of powder) The obtained powder is heat treated at 150 to 500°C before pressure molding. The heat treatment atmosphere may be air, nitrogen, or any other atmosphere, but it is preferable to conduct the heat treatment under reduced pressure (0.0001 to 100 mmHg). The heat treatment temperature is 150 to 500°C, preferably 200°C or higher to increase the heat treatment effect, and preferably 400°C or lower to prevent thermal deterioration of the sample.
The heat treatment time is 0.1 to 100 hours, but preferably 0.5 hours or more and 24 hours or less for sufficient and efficient heat treatment. Further, the heat treatment may be performed after filling the powder into the mold. (Pressure molding of powder) Molding is carried out by filling powder into a cavity of a compression mold, heating and pressurizing the powder according to the method described in JP-A-62-74906 and the like. The molding pressure is 1 million to 1 million Kg/cm ² , 1000 Kg/cm 2 or more to obtain a dense molded product, and 100,000 Kg/cm ² or more in terms of pressure resistance of a mold that is easily available and can be used repeatedly.
cm ² or less is preferable. It is more preferable if it is 3000 to 50,000 kg/cm ² . The molding temperature is 50 to 500°C, preferably 100°C or higher to promote molding and 400°C or lower to prevent polymer decomposition. The atmosphere during pressure molding may be any atmosphere such as nitrogen gas, helium gas, air, etc., but it is preferably carried out under reduced pressure (0.0001 to 100 mmHg). The shape of the molded body is arbitrary, such as a rod shape, a plate shape, and a gear shape. This molded body can be subjected to heat treatment, cutting, cutting, perforation, etc., as necessary. (Effects of the Invention) The method of the present invention provides high elastic modulus (e.g. 3 gigapascals or more) and high heat resistance (e.g. 300°C or more).
film-like, dense and free of cracks and cracks,
Molded bodies of arbitrary shapes such as rods, plates, blocks, cams, gears, etc. can be obtained. [Example] Hereinafter, the present invention will be explained in more detail with reference to Examples. Production example of polyacrylic acid metal powder Powder 0.5 equivalent of polyacrylic acid and 1.0 NaOH in 1200 c.c. of water
A solution containing an equivalent amount of AlCl _3.6 in 300 c.c. of water.
A solution in which 01.0 equivalent of Hz was dissolved was added dropwise with stirring, and the resulting precipitate was filtered, washed, dried, and ground to obtain powder of aluminum polyacrylate with an equivalent ratio of 1:2. Powder - A metal compound solution was added dropwise to the polymer solution shown in Table 1 while stirring, and the resulting precipitate was filtered, washed, dried and crushed to obtain a powder of polyacrylic acid metal salt shown in Table 1. . The formation of metal salts is observed in the infrared absorption spectrum.
Co double bond absorption of 1700 cm ^-1 is COO of 1550 cm ^-1
This was confirmed because the absorption shifted to a resonance structure and the X-ray diffraction spectrum showed an amorphous pattern. Example 1 Powder was filled into a cavity formed by a mold housing material and a cylinder with an inner diameter of 35 mm.
Next, while exhausting the air inside the cavity using a vacuum pump, it was subjected to dry heat treatment at 300℃ for 60 minutes, and then heated to 1000℃.
Pressure molded at 300℃ for 60 minutes with a pressure of Kg/ ^cm2 ,
A disk with a wall thickness of 3 mm and a diameter of 35 mm was obtained. This disk had a specific gravity of 1.85 and was white in color. A rectangular parallelepiped with a length of 15 mm, a width of 3 mm, and a thickness of 3 mm was cut from this disk and cut at 20°C using an autograph manufactured by Shimadzu Corporation at a crosshead speed of 0.5 mm/min.
The compressive modulus of elasticity was measured at 44.0 gigapascals (GPa). Compressive strength is 0.55GPa
It was hot. Also, from this disk, the length is 33 mm, the width is 5 mm, and the thickness is 1 mm.
A rectangular parallelepiped was cut and the temperature dependence of the flexural modulus was measured using a Viblon DDV/manufactured by Toyo Baldwin Co., Ltd. As shown in Figure 1, 400
Even when the temperature was raised to ℃, almost no decrease in the elastic modulus was observed. If the temperature at which the elastic modulus rapidly decreases is defined as the heat-resistant temperature, the heat-resistant temperature of this molded article is 400°C or higher. Examples 2 to 22 The powders were filled into a mold and heat treated and molded under the conditions shown in Table 2 to obtain molded bodies having the physical properties shown in Table 2. Comparative Example 1 After filling the powder into the cavity, while evacuating the air in the cavity using a vacuum pump,
Pressure molding was performed at 200° C. for 90 minutes under a pressure of 10,000 Kg/cm ² to obtain a disk with a wall thickness of 3 mm and a diameter of 35 mm. This disk had a specific gravity of 1.83 and was white in color. The compressive elastic modulus at 20° C. was measured in the same manner as in Example 1, and was found to be 41.6 gigapascals (GPa). The compressive strength was 0.10 GPa. A rectangular parallelepiped with a length of 33 mm, width of 5 mm, and thickness of 1 mm was cut from this disk, and the temperature dependence of the flexural modulus was measured.
The elastic modulus started to decrease rapidly from 230℃ (second
figure). Comparative Examples 2 to 10 Powder was filled into a mold and molded under the conditions shown in Table 3 to obtain molded bodies having the physical properties shown in Table 3.

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【table】 [Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams showing the temperature dependence of the dynamic flexural modulus of the molded bodies molded in Example 1 and Comparative Example 1, respectively. tand……elastic loss rate, E′……modulus of elasticity, E″……
Elastic loss, lGPa=10 ¹⁰ dyne/cm ² .

Claims (1)

[Claims] 1. 100% polyacrylic acid metal salt powder in a mold.
Production of a molded body of polyacrylic acid metal salt, characterized in that the powder is heat-treated at 150 to 500°C before pressure molding, in a method of forming a molded body by pressure molding at a pressure of Kg/cm ² or more. Method.