JPS6219364B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to a method for recycling inorganic glass fiber products, particularly glass fiber mat (hereinafter simply referred to as glass mat), which is a short glass fiber product, that is, a method for producing glass raw materials from glass fiber mat. Involved.

Conventionally, it has been known that defective products, chips, etc. of glass mat products made by collecting short glass fibers in a flocculent form with an organic binder are either disposed of in a landfill or used as a raw material for remelting. Glass pine contains an organic binder, but glass pine is heated to 900℃ as is.
When placed in a glass melting kiln at ~1500°C, the glass melts before the binder decomposes and burns, entraining organic components into the glass and creating carbon amber, which causes undesirable coloration of the glass. Furthermore, if carbon amber is included in the glass, the glass becomes strongly reduced, which can damage platinum caps for thermocouples used in glass melting furnaces, platinum covers for refractories, and various platinum parts in glass fiber manufacturing equipment. There is a drawback that it does.

In order to eliminate these drawbacks, a method for recycling glass pine by removing organic binders from glass pine is known, and has been patented in the United States.
No. 3,852,108 describes a method for burning off the binder in the mat by heating the glass mat to a temperature lower than the softening point of the glass and higher than the combustion temperature of the organic binder.

Although the glass matte from which the binder has been removed can prevent the above-mentioned glass coloring and damage to platinum parts, its bulk specific gravity is as low as 0.005 to 0.05, which is the same as glass matte products, and it is difficult to put it into a glass melting kiln. has the disadvantage of being difficult to handle. In other words, it is difficult to use the glass mat when it is fed into the glass melting kiln using a screw feeder because it gets clogged in the middle. Furthermore, when glass mat is mixed together with a powder batch of glass raw materials in a mixer for mixing glass raw materials, there is a disadvantage that if the mixing ratio of glass mat is 10% or more, it becomes bulky and difficult to put into the mixer. In addition to this difficulty in handling, if the glass mat from which the binder has been removed is placed in a gas-fired or heavy oil-fired glass melting kiln, the glass fiber waste contained in the mat will fly up on the air currents in the kiln and blow up against the walls of the kiln. It has the disadvantage that it adheres to the kiln ceiling and heat storage room bricks and corrodes them.

The object of the present invention is to eliminate such drawbacks and to obtain a glass raw material from a glass mat that is easy to handle and is free from the risk of corroding the melting furnace refractories.

As a result of extensive research, the present inventors have found that by heating at an appropriate temperature above the softening point of the glass constituting the glass mat, the organic binder can be removed by decomposition and combustion, and the glass can be made into a semi-molten state, reducing its surface tension. It was discovered that the glass fibers constituting the glass mat can be caused to self-shrink, and the entire glass mat can be sintered into a plate shape. This plate-shaped sintered body does not bulk up during handling or transportation, does not scatter when put into a glass melting furnace, and is an excellent glass raw material that does not leave a large amount of carbon amber in the glass even when melted. I discovered something.

In the present invention, the bulk specific gravity of the glass fiber mat is reduced by heating the glass fiber mat within a temperature range such that the viscosity of the glass constituting the mat becomes 10 to the 7.0 power poise and 10 to the 4.0 power poise, respectively. This method also produces glass raw material from glass fiber mat, which is characterized by shrinking the glass fiber mat until its shrinkage increases to 0.08 to 1.2.

In the present invention, when the glass mat is heated within the range of a temperature where the viscosity of the glass constituting the glass mat becomes 10 to the 7.0 power poise and 10 to the 4.0 power poise, the glass softens and becomes fluid, and the surface Strong tension acts on the glass fibers, causing them to contract in the axial direction in an attempt to reduce their surface area, and welding also occurs at the intersections of the fibers, resulting in a sintered state.

Glass pine contains a large amount of air between its fibers, so the fusion and sintering of the fibers progresses slowly, and by the time the glass pine surface is sintered and the pores on the surface are sealed, Decomposition, vaporization, or combustion of the organic binder containing the glass mat occurs, and most of it exits through the pores on the surface of the glass mat. After this heat treatment, the material becomes a plate-like material with a smooth surface, a porous interior, and a bulk specific gravity of 0.08 to 1.2. Such a heat-treated product is easy to handle, and glass fiber waste will not scatter even if it is put into a gas-fired or heavy oil-fired glass melting kiln as a raw material for glass.

If the glass mat is heated at or below the softening point of the glass (the temperature at which the viscosity of the glass is 10 to the 7.65th power), no shrinkage or sintering of the glass mat will occur. Most of the fibers are lost, and the fibers become fragmented, making it extremely easy for glass fiber waste to scatter during handling or when feeding into a glass melting kiln. Furthermore, if the glass mat is heated to a temperature that is higher than the softening point of the glass but lower than the temperature at which the viscosity of the glass is 10 to the 7.0 power, it will take a long time for the glass mat to shrink and sinter.
This is not preferred because sintering tends to be uneven.

On the other hand, the glass matte has a viscosity of 10 to 4.0
If the glass is heated to a temperature higher than the temperature at which it becomes a poise, the glass will melt, shrink, and sinter too quickly, and the organic binder described above will not have enough time to decompose, burn, and come out. The surface of the glass pine becomes sealed before the glass mat is exposed, and the organic binder is trapped inside the glass, mainly in the form of carbon.

As mentioned above, the heating temperature of the glass mat is determined by the viscosity of the glass fibers that make up the glass mat.
It is necessary to keep the temperature within the range between the temperature that becomes 7.0 poise and the temperature that becomes 10 4.0 poise. There is no problem in heating the glass mat to a temperature lower than the above temperature range before, during or after heating within this temperature range. However, it is not preferable to heat the glass mat to a temperature higher than the temperature range before or during heating within the temperature range. This is because once the pores existing on the surface of the glass mat are sealed, it becomes difficult to extract the organic binder trapped inside the glass mat to the outside of the glass mat.

By adjusting the heating temperature and heating time, shrinkage of the glass mat and bulk specific gravity of the sintered body can be controlled.
It is preferable that the shrinkage sintered body has no fluff and can be easily crushed to a predetermined size.

In the present invention, the atmosphere of the glass mat when heating the glass mat does not necessarily have to be air or an oxidizing atmosphere, but the combustion of the organic binder in the glass mat helps the heating of the glass mat to some extent, so air or an oxidizing atmosphere is necessary. preferable.

In the method according to the present invention, when heating to a temperature in the above range, the time required for the heat treatment varies depending on the heating temperature, but from a thermoeconomic point of view, it is convenient to take about 1 to 5 minutes.

When the glass mat is exposed to the above processing temperature from room temperature, the organic binder comes out of the glass mat in about 10 to 60 seconds, and sintering takes about 30 seconds.
Since the process is completed in seconds to 90 seconds, a processing time of 1 to 2 minutes is sufficient. Even if the heat treatment time is longer than 2 minutes, shrinkage and sintering do not proceed any further.
In addition, the organic binder contained in the glass mat is first treated at a temperature lower than the temperature at which the viscosity of the glass becomes 10 to the 7th power, and then the temperature at which the glass viscosity becomes 10 to the 7.0 power poise and 10 to the 4.0 power poise. Heating may be carried out within a temperature range, but this is disadvantageous because it requires larger equipment and the heat of combustion of the organic binder cannot be used for fusing and sintering the glass fibers. It is economically advantageous to expose the room temperature glass mat to the above temperature range all at once.

The higher the surface tension at high temperatures of the glass itself constituting the glass mat treated in the method of the present invention, the better the results obtained. This is because, as mentioned above, if the glass fiber shrinks significantly above the temperature at which the viscosity of the glass becomes 10 to the power of 7.0 poise, it tends to become a high-density plate-like material. For example, the composition of the glass constituting the glass mat is 35% to 47% by weight of _SiO2 , 9% to 15% by weight _{of Al2O3} ,
18wt%~40wt% for CaO, 0wt%~ for MgO
7% by weight, a total of 0% to 19% by weight of Na ₂ O and K ₂ O, and 1% to 8% by weight of B ₂ O ₃ (temperature at which the viscosity becomes 10 to the power of 7.0 poise;
The surface tension is particularly high at temperatures of 450 to 600℃ (also 10 to the power of 4.0 poise; 700 to 900℃).
A high-density treated product can be obtained by heat-treating for at least 60 seconds at 550 to 800°C and within the temperature range where the viscosity of the glass is between 10 to the 7.0 power poise and 10 to the 4.0 power poise. Also, SiO ₂ 38~42, Al ₂ O ₃ 12
~15, CaO18~25, MgO1~5, if either or both of Na ₂ O and K ₂ O is included, the total 12 ~
19, Glass having a composition of 5 to 8% by weight of each B ₂ O ₃ (The temperature at which the viscosity becomes 10 to the 7.0th power poise is 470 to 550°C
Similarly, the temperature at which 10 to the 4.0 power poise is 780
The surface tension of glass matte, which is made up of 10 to 7.0 poise, is 580 to 750 degrees Celsius.
A glass raw material, which is a high-density processed material, can be obtained by heating for at least 30 seconds within a temperature range of 4.0 poise.

In the method of the present invention, it is efficient to heat the glass mat in the form of radiant heat. 550℃
When glass mats are heated by conduction heat using a large amount of hot air at temperatures as high as ~800℃, energy leaks out of the heating furnace, resulting in poor efficiency.

Infrared radiant heaters and radiation burners are used to provide heat in the form of radiant heat. However, even if the frame of an ordinary gas burner, which is not a radiant heat type, is applied directly to the glass mat, the glass shrinkage and sintering phenomenon described above will not be observed. This is limited to radiation-type burners that receive radiant heat from red-hot burner tiles (for example, commercially available HFB-1R manufactured by Chugai Roko Kogyo KK).
(S) type or HFB-0.5R (S) type) is preferable. ) The radiant heat is well absorbed into the interior of the glass mat, and is also well absorbed by the glass itself. In addition, organic binders for glass mats such as phenolic resins and urea resins are heated by heat transfer from the glass or by direct radiant heat and are quickly decomposed, so they have the advantage that they do not remain in the form of carbon after heating.

The glass mat used in the present invention is not limited to the shape of a band or plate, but may have any other shape such as a hollow cylinder or a rod. Furthermore, a glass mat of such shape may be cut into any size. The sintered body obtained by heating and shrinking the glass mat can be used as a raw material for glass either as it is or by crushing it if necessary.

Next, the present invention will be explained by giving examples.

Example 1 The composition of glass is SiO ₂ 40.0 expressed in weight%
%, _{Al2O3 13.0} %, CaO19.0%, MgO3%,
Fiber diameter approximately 4 microns, bulk specific gravity 0.008g/cm ³ , resin content 7.0%, thickness 60mm, height 200mm, consisting of Na _{2 O} 14.5%, K ₂ O 3.5%, B 2 O ₃ 7.0%. The viscosity of the glass pine cut into 200mm wide pieces is
When the glass mat was placed in a nichrome wire heating furnace with a volume of 8 liters and a power of 5 KW at an ambient temperature of 620°C, which is the temperature of 10 to the 5.8 poise, and held for 2 minutes, more than 90% of the resin content of the glass mat decomposed. It was burned and removed, and it shrunk into a plate with a thickness of 1.5 mm, a height of 120 mm, and a width of 120 mm, with a bulk specific gravity of 0.85. The surface was smooth and not fluffy, and by applying a little force, it could be broken into a shape that could be easily used as a raw material for melting in a glass-melting kiln, like a rice cracker.

Example 2 The composition of the glass expressed in weight% is SiO ₂ 40.0
%, _{Al2O3 13.0} %, CaO23.5%, MgO3.0%,
Fiber diameter approximately 4 microns, bulk specific gravity 0.008, resin content 7, consisting of Na ₂ O 12.0%, K ₂ O 2.0%, B ₂ O ₃ 6.5%
A glass mat cut into pieces 60mm thick, 200mm long, and 200mm wide was heated to an ambient temperature of 670℃, the temperature at which the viscosity of the glass is 10 to the power of 5.8 poise, using a nichrome wire with a volume of 8 liters and a power of 5KW. When treated in a furnace for 2 minutes, almost 100% of the resin contained in the glass pine was decomposed, burned and removed, and the glass pine shrunk to a size of 2 mm thick, 150 mm long, and 150 mm wide, and became a plate with a bulk specific gravity of 0.42. It became. As in Example 1, it was possible to form a shape that was easy to use as a raw material for melting.

Example 3 Glass composition expressed in weight percent: SiO ₂ 72.7
%, _{Al2O3 1.8} %, _{Fe2O3 0.1} %, CaO7.3%,
Fiber diameter approximately 4 microns, bulk specific gravity 0.008g/cm ³ , resin content 7%, thickness 60mm, length 200mm, width 200mm, consisting of MgO 3.9%, Na ₂ O ₃ 13.4%, K _{2 O} 0.8% The viscosity of the glass is
When the glass mat was treated for 2 minutes in a nichrome wire heating furnace with a volume of 8 liters and a power of 5 kW at an ambient temperature of 750°C, which is the temperature of 10 to the 5.8th power poise, almost 100% of the resin contained in the glass mat was decomposed and burned. It was removed and shrunk into a plate with a thickness of 8 mm, a height of 150 mm, and a width of 150 mm, and a bulk specific gravity of 0.11. As in Example 1, it was possible to make it into a form that was easy to use as a raw material for melting.

Example 4 As shown in the figure, the composition of the glass expressed in weight percent is SiO ₂ 40.0%, Al ₂ O ₃ 13.0%, CaO 19.0%,
MgO3.0%, _Na2O14.5 %, _K2O3.5 %, _{B2O3 7.0} %
Fiber diameter approximately 4 microns, bulk specific gravity 0.008g/
^cm3 , resin content 7.0%, thickness 60mm, width 100mm, length
50m glass mat roll product 1, length 10m, width
The gas is conveyed by a stainless steel net conveyor 2, which is 2.5 m long and 1.5 m high, and has an ambient temperature of 600 to 670°C, where the viscosity of the glass is 10 to the 6.0 poise to 5.4 poise. When the pine roll product was passed through the heating furnace 3 in a belt shape at a passing speed of 5 m/min, almost 100% of the resin contained in the pine roll product was removed, and the entire roll product was in the shape of a belt with a thickness of 4 mm and a width of 800 mm. It contracted (the length remained unchanged at 50 m) and became a plate with a bulk specific gravity of 0.19. When this was broken into pieces approximately 50 mm x 50 mm in size using a simple crusher 4 and placed in a heavy oil-burning glass melting kiln (not shown), it was possible to melt the fibers without scattering them. The structure of the gas heating furnace 3 is as shown in the figure, and 60 radiation-type gas burners 5 are mounted on the ceiling 6 facing downward. Burner 5 has a combustion capacity of 15000Kcal/
Hr (HFB-1R (S) manufactured by Chugairo KK) was used, and butane gas was used as the burner fuel.

[Brief explanation of the drawing]

The drawing is a sectional view showing an example of an apparatus for implementing the present invention. 1...Glass fiber mat, 2...Net conveyor, 3...Heating furnace, 4...Crusher, 5...
Radiation type burner.

Claims (1)

[Claims] 1. The temperature at which the viscosity of the glass constituting the glass fiber mat becomes 10 to the 7.0th power poise and 10
A method for producing a glass raw material from glass fiber mat, which comprises shrinking the glass fiber mat until its bulk specific gravity increases from 0.08 to 1.2 by heating within a temperature range of 4.0 poise. 2. The method for producing a glass raw material according to claim 1, wherein the heating is performed using a radiant burner. 3 The glass fiber mat has a composition of SiO ₂ 35-47 Al ₂ O ₃ 9-15 CaO 18-40 MgO 0-7 (Na ₂ O + K ₂ O) 0-19 B ₂ O ₃ 1-8 by weight. A method for producing a glass raw material according to claim 1 or 2, which is made of glass. 4. The method for manufacturing a glass raw material according to claim 3, wherein the heating temperature is 550°C to 800°C. 5. The method for producing a glass raw material according to claim 3 or 4, wherein the heating is performed for at least 60 seconds. 6 The glass fiber mat has a composition of SiO ₂ 38-42 Al ₂ O ₃ 12-15 CaO 18-25 MgO 1-5 (Na ₂ O + K ₂ O) 12-19 B ₂ O ₃ 5-8 by weight. A method for producing a glass raw material according to claim 1 or 2, which is made of glass. 7. The method for producing recycled glass raw material according to claim 6, wherein the heating temperature is 580 to 750°C. 8. The method for producing a glass raw material according to claim 6 or 7, wherein the heating is performed for at least 30 seconds.