JPS6257580B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composition for glass fibers having excellent alkali resistance. Glass fibers used as reinforcing fibers in glass fiber reinforced concrete (GRC) to make concrete thinner and lighter, and as substitute fibers in asbestos slate to reduce the amount of asbestos, are required to have alkali resistance. The reason is that the main component of Portland cement, the raw material for the matrix, is 3CaO.
It is _SiO2 , and in the reaction process in which these react with water to form and harden tobermorite gel, a large amount of calcium hydroxide is produced, and the pH of the aqueous solution that is in equilibrium with this increases to 12.5 to 13.0. This can be expressed as a chemical formula as follows. 2(3CaO−SiO ₂ )＋6H ₂ O → 3CaO・2SiO ₂・
3H ₂ O＋3Ca(OH) ₂ 2(2CaO・SiO ₂ )＋4H ₂ O→3CaO・2SiO ₂・
3H ₂ O + Ca (OH) ₂ Therefore, long fibers of E glass, which are often used in glass fiber reinforced plastics (FRP), deteriorate rapidly in such a highly alkaline atmosphere, so it is necessary to use alkali-resistant glass. It requires fiber. The typical composition of alkali-resistant glass fiber is:
It is based on SiO ₂ −Na ₂ O−ZrO ₂ , and its alkali resistance depends on a high content of ZrO ₂ . This type of material has problems in profitability because the raw materials are expensive and the melting and spinning temperatures are high. In addition, long glass fibers such as E-glass are
Since B ₂ O ₃ is used as flux,
B ₂ O ₃ has the drawback of significantly damaging refractories and severely deteriorating the alkali resistance of glass. The present invention solves the above-mentioned drawbacks by making the melting temperature and spinning temperature (working temperature) relatively low without using B ₂ O ₃ , thereby reducing damage to the melting furnace, platinum bushings, etc. An object of the present invention is to provide an alkali-resistant glass fiber composition which has excellent workability by increasing the difference between the spinning temperature and the liquidus temperature, and further reduces the yarn breakage phenomenon and is excellent in economical efficiency. The gist of the composition for alkali-resistant glass fibers according to the present invention is as follows: SiO ₂ 64-68% by weight Al ₂ O ₃ 1-5 RO 5-11% by weight R' ₂ O 7-13 ZrO ₂ 8 ~13〃MoO30.1 _~ 0.5〃CdO0.1~ _0.5〃Fe2O3 , FeO0.5 _~ 1.0〃It is characterized by having a composition consisting of. Here, R represents Ca, Mg or Ba, and R' is
Represents Na or K. Next, each of the above composition components will be explained in turn. SiO ₂ is a skeletal component of glass,
From the viewpoint of alkali resistance and melt temperature spinning workability
Contains 64-68% by weight. Al ₂ O ₃ is effective in increasing the water resistance of the glass and suppressing devitrification caused by the CaO component, but if it exceeds 5% by weight, it becomes difficult to dissolve the ZrO ₂ component, so the content should be 1 to 5% by weight. be. RO represents CaO, MgO, and BaO, and contains 5 to 11% by weight of these alone or in combination. RO acts as a melting agent and imparts alkali resistance, and if it is less than 5% by weight, it cannot be expected to be effective as a melting agent, and if it is more than 11% by weight, it is accompanied by an increase in liquidus temperature, which is not desirable. . R′ ₂ O is Na ₂ O,
It represents K ₂ O and contains 7 to 13% of these alone or in combination as a flux. If R' ₂ O is less than 7% by weight, melting of SiO ₂ and ZrO ₂ cannot be expected, and if it is more than 13% by weight, the water resistance decreases, which is not preferable. ZrO ₂ provides alkali resistance and has a
Contains ~13% by weight. If it is less than 8% by weight, alkali resistance cannot be expected, and if it is more than 13% by weight, a high temperature is required during melting, and the temperature-viscosity curve shifts to the high temperature side. An increase in the spinning temperature (1000 poise) has the disadvantage of shortening the life of platinum bushings.
The ZrO ₂ component is not used alone, but is mixed and adjusted as SiZrO ₄ . MoO ₃ and CdO provide meltability and alkali resistance, respectively, and are characteristic components of the present invention. Since MoO ₃ and OdO are expensive raw materials, the content thereof is set to 0.5 to 1.0% by weight, respectively. Fe ₂ O ₃ and ReO are mixed to improve workability and are contained in an amount of 0.5 to 1.0% by weight. In addition to the above active ingredients, MnO and other impurities
Although TiO ₂ is contained in an amount of 0 to 1 wt%, it does not have any adverse effects on the implementation of the present invention. Although the components have been explained above, in general when spinning glass fibers, it is necessary to keep the working temperature below 1300°C, preferably below 1250°C, from the viewpoint of the heat resistance and strength life of the platinum bushing.
In this case, it is preferable to use a glass composition in which the glass melt viscosity at the working temperature is 10 ³ poise, the temperature-viscosity curve does not rise much, and the liquidus temperature is 50°C, preferably 100°C or more lower than the working temperature. It is necessary. Next, the outline of the manufacturing process for the alkali-resistant long fiber glass composition according to the present invention will be explained. In carrying out the present invention, the main raw material is shirasu, a natural glassy raw material that is widely deposited in the southern Kyushu area. Some care is required when handling whitebait, so the reason and handling will be explained below. The chemical composition of whitebait varies slightly depending on the production area, but Table 1 shows some examples from Kagoshima Prefecture.
As shown in this table, SiO ₂ is 71-73% and Al ₂ O ₃ is 13%.
~14%, Na ₂ O and K ₂ O about 6%, CaO about 2%, and iron oxide about 2%. Shirasu also contains 70-80% by weight of glass and 20-30% by weight of minerals, mainly plagioclase.

[Table] Next, Table 2 shows the chemical and mineral composition of whitebait from Takeoka according to particle size.

[Table] As can be seen from this table, whitebait coarser than 100 mesh contains a large amount of plagioclase. This plagioclase is difficult to melt and often causes breakage, especially when harvesting long fibers, so it is preferable to use shirasu that is thinner than 100 mesh or elutriated or elutriated shirasu that is rich in glass content. . In addition to this main raw material, CaCO ₃ ,
Mix appropriate amounts of NaCO ₃ , SiZ ₂ O ₄ , CdOMoO ₃ , etc.
These are melted in a melting furnace and vitrified. Next, the fibers are spun from a platinum bushing provided in a forehouse through a throat and a working tank, and a sizing agent is applied to the surface of the fibers, which is then wound into a cake shape with a forming winder and dried. Obtain long fiber strands. Next, 22 examples relating to the present invention are listed in a table and will be described in detail below.

【table】

【table】

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[Table] The above 22 Examples were carried out as follows. The main raw material, whitebait, is purified whitebait obtained by elutriation, and its composition is as shown below. SiO ₂ 71.5% by weight Al ₂ O ₃ 12.0 〃 CaO 1.0 〃 MgO 0.9 〃 Fe ₂ O ₃ 1.7 〃 Na ₂ OK ₂ O 6.6 〃 TiO ₂ 0.1 〃 MnO 0.4 〃 Ig−Loss 2.9 〃 First, liquidus temperature and working temperature To measure, 22
The glass raw materials of the example were weighed and prepared, and melted in an electric furnace at 1500°C for 3 hours using a platinum crucible to obtain a glass cullet. The liquidus temperature was measured using a glass devitrification tester by determining the upper limit temperature for crystal precipitation maintained for 8 hours. The working temperature was measured at a temperature equivalent to 10 ³ poise using a platinum ball lifting type viscosity balance. Next, a spinning test was conducted using an electric melting furnace equipped with a 204-hole platinum bushing in the forehouse. This electric melting furnace has a melting temperature of 1500°C and a flow rate of 15 kg/hr, and is a direct melting type spinning furnace that can perform everything from feeding the raw materials to applying a sizing agent and harvesting the yarn. When implementing the above 22 examples, the glass fabric was continuously flowed out of the furnace from the platinum bushing until the inside of the furnace was replaced with the specified glass composition, and the composition was analyzed using a fluorescent X-ray analyzer to ensure complete replacement. After confirming that it was possible, we conducted a yarn sampling test on 22 cases. The forming winder in this case has a drum diameter of 285 mm and rotation speeds of 1200, 1500, and 1900 rpm. In addition, the alkali resistance of glass fibers can be confirmed by determining the rate of change in tensile strength, weight, and rate of decrease, which was carried out as follows. The rate of change in tensile strength was calculated using the strands of 13 μm long fibers obtained by this spinning method, and the rate of weight loss was calculated using separately collected glass cullet, which was crushed to a particle size of 0.5 to 1.0 mm. It was used as a sample. These were mixed with IN-NaOH aqueous solution and synthetic cement extract [NaOH: 0.88g/KOH: 3.45
g/Ca(OH) ₂ :adjusted to a ratio of 0.48 g/
PH-12.5 test solution] was put into a round bottom flask equipped with a reflux condenser, heated at 80℃ for a specified time, taken out, washed with water, dried, and then measured for weight loss rate and tensile strength change rate of the fiber. I asked for it. The results are shown in the middle and lower rows of the Examples table. Examples 1 to 22 are listed as Examples, and Examples 1 to 17 are desirable examples whose performance as a product composition satisfies the initial purpose of the present invention, and Examples 18 to 22 are examples. By decreasing or increasing the content percentage of some components of the composition for alkali-resistant glass fibers according to the present invention from the content percentage defined by the gist of the present invention, defects that are not suitable for the purpose of use as a result. This is an example of this being pointed out. 18-22 cases are 1
When compared with Examples 1 to 17, it can be seen that increasing or decreasing one part of the component greatly affects the properties of the resulting composition. In addition, in order to compare with E-glass, we obtained commercially available long fiber strands and conducted an alkali resistance test using the powder as it was or after melting and cooling in a platinum crucible and pulverizing it to a particle size of 0.5 to 1.0 mm. did. It can be seen that both the weight loss rate and the tensile strength change rate in the alkali resistance test are significantly inferior to those of the present invention. As described above, the present invention has lower melting and spinning temperatures than conventional ones, which reduces damage to the melting furnace, platinum bushings, etc., and increases workability by increasing the difference between the spinning temperature and the liquidus temperature. In addition, it has excellent economical effects with less thread breakage.

Claims (1)

[Claims] 1 SiO ₂ 64-68% by weight Al ₂ O ₃ 1-5% by weight RO 5-11% by weight R' ₂ O 7-13% by weight ZrO ₂ 8-13% by weight MoO ₃ 0.1-0.5 A glass composition for alkali-resistant fibers consisting of: CdO 0.1-0.5 wt% Fe ₂ O ₃ and FeO 0.5-1.0 wt % (wherein R represents Ca, Mg or Ba and R' represents Na or K) .)