JPS60155558A - Gypsum board blend - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to gypsum board formulations, particularly gypsum board formulations with high fire resistance.

It is well known to those skilled in the art that gypsum board products generally consist of a core of hardened gypsum and a cover sheet (usually paper) covering the core. Gypsum board products are widely used as interior wall and ceiling materials, including gypsum panels, plasterboard,
It is used as plaster wallboard, etc.

Since gypsum board binds water (approximately 21% by weight of gypsum), it is extremely useful as a fire barrier layer for various building materials. When a gypsum board compound or a hardened plaster compound receives heat from a flame, its internal moisture is slowly released as steam, thereby retarding heat transfer while acting like a plaster cast. In this case, the heat resistance of various gypsum building materials is determined by fire resistance tests on samples conducted in accordance with procedures established by ASTM (American Society for Testing and Materials). For example, ASTM Regulation 03.6 Section 3.3 specifies Special Flame Retardant Markings for Stone Wall Panels, Type
is determined. That is, AEITM regulation E11
The thickness of the gypsum board, h inches (16 mm
) for plasterboard with a flame retardant rating of at least one hour,
In addition, a flame retardant rating of 45 minutes is specified for gypsum board with a thickness of A inch (13 mm).

For example, as a result of investigating the changes in gypsum board when exposed to flame during fire protection tests in the laboratory, it was found that when the core of gypsum board is placed at high temperatures, it generally shrinks to a large size, which causes cracks. It has been found that excessive heat is allowed to pass through the gypsum board, causing it to rapidly fail. That is, as the gypsum is fired, it changes and its hardening strength decreases.

To increase the fire resistance of gypsum board products, traditionally during gypsum board forming certain fibers and non-expandable vermiculite are mixed into a slurry of calcium sulfate hemihydrate (plaster or calcined gypsum or gypsum stucco) and water. was added to. Such technical ideas are described in U.S. Patent No. 2,526,066,
No. 681,861, No. 2゜744.022, No. 2,8
No. 03,575, No. 2,853,394, No. 3,45
No. 4,456 and No. 3,616,173, etc. In this case, the shrinkage of the gypsum board is supplemented by the action of non-foaming vermiculite during heating of the gypsum board. That is, vermiculite expands as bound water in the gypsum is removed.

On the other hand, heating deteriorates the cohesiveness of gypsum and reduces the strength and cohesiveness of the gypsum core, but the fiber components in the gypsum core increase the mechanical cohesion of the entire gypsum core, preventing the gypsum core from collapsing. Ru.

Additionally, U.S. Pat. No. 3,616,173 discloses a structure in which the fire resistance of a gypsum board core is further improved by incorporating a certain proportion of small inorganic particles and non-expandable vermiculite into the gypsum board core. ing.

In this case, clay with a particle size of 1 μm or less to about 40 μm and colloidal silica or colloidal alumina or a mixture thereof with a particle size of less than 1 μm are mixed, and this and the mineral fiber mixture work together to impart high fire resistance. It is thought that On the other hand, according to U.S. Patent No. 3,454,456, the presence of non-expandable vermiculite mixed in a certain proportion of fine particles of 100 mesh (147μrIL) or less causes large cracks and cracks in the gypsum board core. Occurrence is prevented. According to the patent, in order to reduce shrinkage and cracking due to flame, the US standard 50 mesh (297 μr
It is necessary to prepare non-expandable vermiculite with a particle size that can pass through a 140 mesh (105 μm) sieve.

The sample of the gypsum board core according to the present invention was heated once and then subjected to a fire protection test after a period of time. As a result, no shrinkage occurred at all, and 0.15 inches (0.0,0
It was found that it expanded to 38(II). It was also found that the gypsum in the gypsum board sample changed to anhydrite H during the initial heating. Thus, the present invention uses anhydrite in the formulation of the gypsum board core. This anhydrite can be thought of as a gypsum additive that has been pre-heat treated and pre-shrunk to improve fire resistance.

One object of the present invention is to provide a gypsum board formulation with high fire resistance.

Another object of the present invention is to provide a fire-resistant gypsum board composition that expands without being contracted by dew flames and has good bonding properties to heated gypsum material.

This object of the present invention is to mix about 2 to 40 weight of calcium sulfate anhydrite (1) alone or with a small amount of glass fiber or non-expandable vermiculite instead of mixing non-expandable vermiculite into plaster as in the past. This can be achieved by adding it in a mixture with stone or wollastonite.

The present invention will be explained below along with preferred embodiments.

The main component of the gypsum formulation, such as the fire-resistant gypsum board according to the invention, is set gypsum, i.e. calcium trisulfate, hydrated crystals of calcined gypsum slurried with water and known additives by well-known methods. Obtained by converting into As calcined gypsum, natural or synthetic alpha or beta hemihydrate, soluble anhydrite, or mixtures thereof can be used. Also known are additives, such as blowing agents, to impart desired properties to the gypsum formulation and to facilitate manufacturing.
Accelerators, retarders, dispersing aids, core adhesives, and mixtures thereof may be used and are added in predetermined amounts to the gypsum formulation.

For example, when manufacturing gypsum wallboard, the dry ingredients and water are first weighed into a mixer and an amount sufficient to produce a pourable aqueous slurry, such as a dilute surfactant foam solution, is added to the mixer and foamed to form a slurry of the mixture. Core material is made by adjusting the density. The mixture slurry is then removed from one or more outlets in the bottom of the mixer and discharged onto a moving conveyor carrying a cover sheet, such as a multi-ply paper.

Another cover sheet, such as a multilayer paper, is then placed on top of the slurry resting on one cover sheet.

This places the slurry between two cover sheets (which will be on opposite sides of the gypsum board product) that are moved by a moving conveyor.

In this case, the thickness of the plasterboard is adjusted by passing it through forming rolls, while the mutually overlapping edges of the two cover sheets are continuously scored by suitable mechanical devices at the edges of the plasterboard. The gypsum board is enclosed within the two cover sheets by folding it over and applying adhesive. Further, a moving conveyor moves the slurry on the belt, and simultaneously with the hardening of the slurry, a guide member maintains the thickness and width of the gypsum board at desired values. The plasterboard is then cut, the edges treated and sent to the drying section for drying.

The gypsum board of the present invention thus obtained is a gypsum board core consisting essentially of hardened gypsum and a layer of calcium sulfate anhydrite. Calcium sulfate is insoluble in water, unlike other soluble substances.

The gypsum board core may also include glass fibers to increase strength and bonding. On the other hand, anhydrite may be added to a gypsum formulation, such as a gypsum board core, in addition to the amount of gypsum, and anhydrite may be substituted for a portion of the amount of gypsum. The gypsum board core may also include an additional inorganic mineral filler, particularly about 1 to 5 weight percent of acicular particle wollastonite (CaS 103) or unexpanded vermiculite.

Furthermore, it is preferable to use slow-fired anhydrite (■), especially one consisting of fibrous particles with an aspect ratio of more than 20:1, but early-fired anhydrite (■) may also be used. Can be used.

Hard-fired (
Anhydrite (calcined at temperatures above 1200°C) can be used similarly to natural anhydrite. It is also possible to use a mixture of different anhydrite. If only the anhydrite layer is used, it will contain about 2 to 40 percent by weight, but especially wollastonite,
Unexpanded vermiculite or glass fiber fillers, if included, may amount to about 1 to 10 weight percent.

Specific examples of the gypsum formulation according to the present invention will be shown below.

In this case, the units of amounts are parts by weight unless otherwise specified. Furthermore, it will be understood that the present invention is not limited to these examples, but includes design changes that fall within the technical spirit of the claims.

Experimental Example 1 Each of the formulations in this experimental example was molded onto paper-covered gypsum board with a nominal thickness of 1.3 mm on a production line. All gypsum boards are molded substantially the same, and the types of included set modifiers, consistency reducers, bonding aids, blowing agents, water, and other adjuvants are also substantially the same for each board. did. 15.25m x 25.5m aliquot (sample)
Panels were cut from each gypsum board and tested on a small scale for fire resistance.

For small-scale fire resistance tests, cut samples were placed vertically at the front of a test furnace made of refractory bricks and having a front opening 0.635 m larger than the sample. The test furnace was equipped with a plurality of natural gas burners, which applied the burner flame globally rather than locally to the sample, resulting in a substantially uniform temperature along the flamed surface of the sample.

The temperature inside the test furnace and the temperature of the flame-receiving surface of the sample were measured by thermocouples. The sample was placed in the bracket of a spring strain gauge, and the state of expansion and contraction of the sample was measured during a one-hour fire resistance test. In each refractory test, the temperature of the test furnace was adjusted to match as closely as possible the same time-temperature curve. Furthermore, in this case, after placing the sample in place, the test furnace was ignited and the temperature of the test furnace was increased from 538'O to 593'0 during the first 5 minutes of the fire test, and from 746'O to 755'C during the 10 minutes. let it rise to
The temperature was maintained at approximately 755°C for the remainder of the test period.

With conventional gypsum board cores that do not contain fireproofing additives, the paper to be recycled usually burns during the first 10 minutes of the fire resistance test, expands by approximately 0.05 to 0.06 m due to the heat, and then the fired gypsum board core It began to shrink as plaster.

Maximum shrinkage usually occurred during the first 40 minutes of the fire test.

Also in this series of fire resistance tests, fire resistant formulations were made in accordance with the above-referenced US patents which included unexpanded vermiculite and chopped lath fibers as comparative reference samples.

The anhydrite used in Samples 2 to 5 was granular hard-calcined calcium sulfate anhydrite pulverized to an average particle size of 1.5 micrometers. The degree of bonding of each sample was visually observed during and at the end of the fire resistance test. The sample containing non-expandable vermiculite developed micro-cracks due to expansion and weakened the board core, unable to maintain its original shape. On the other hand, when anhydrite was included, the gypsum core baked smoothly, had good bonding properties, and did not develop microcracks.

Further, the results of Comparison Standard Sample 1 and Samples 2 and 3 are shown graphically in FIG. 60 for non-expandable vermiculite and anhydrite sample 2 without glass fibers.
It can be seen from the graph in Figure 1 that the difference in expansion and contraction during the minute fire resistance test is smaller than that of the comparative reference sample. In the case of Sample 3, sufficient fire resistance can be achieved by significantly reducing the amount of anhydrite and including non-expandable vermiculite. Although sample 4 is not shown in Figure 1, when the amount of anhydrite and gypsum added was less than half that of sample 3, the shrinkage characteristics within 30 minutes at the highest stage of the fire resistance test were the same as sample 3. Although sample 5 contained a low amount of anhydrite and did not contain non-foaming vermiculite, the expansion and contraction properties of the anhydrite mixture were extremely good.

Experimental Example 2 In this experimental example, a fire resistance test was conducted in the same manner as in Experimental Example 1. In this case, some of the hemihydrate used in the gypsum board slurry was replaced with anhydrite material, and small-sized paper-proofed gypsum boards were made on an experimental scale gypsum board forming line. The data shows the amount of granular anhydrite used for this. In addition, the Franklin fiber (FRA) used in this experiment
NFIBER' (registered trademark) filler is anhydrite-like calcium sulfate whiskers having single crystals with an average diameter of about 2 μm and a length usually between 50 and 60 μm. For convenience of presentation, only the cumulative shrinkage after a one-hour fire resistance test is shown.) From the above results, it is clear that gypsum boards with excellent fire resistance can be obtained using various amounts of anhydrite. Dew. In sample 8, anhydrite was crushed to an average particle size of 12 μm, while in sample 9, anhydrite was crushed to an average particle size of 8 μm, and the shrinkage properties were equivalent to those using non-expandable vermiculite and glass fiber. Obtained. Samples 12 to 14
In Samples 15 to 17, finely ground granular anhydrite filler was included, and the shrinkage changed from a state of 0 to an expanded state, and in Samples 15 to 17, small anhydrite whisker fibers were included. The state changed from a slightly contracted state to an expanded state.

Experimental example 3 Using mass-production scale gypsum board manufacturing equipment, the nominal thickness was 1.3
1.27 IB x 3.
A large-scale fire resistance test was conducted using a 6-meter-long structure.

In this fire resistance test, the above-mentioned gypsum panels were screwed onto 89WL11L steel studs, like an unloaded bearing wall, and were placed in a heat-conducting state according to ASTM (American Society for Testing and Materials) standards. It was monitored by nine thermocouples arranged in accordance with -119. According to this test, (1) before the average temperature value of the thermocouple a-1 attached to the unheated surface of the gypsum panel that does not directly receive the heat rises by 200°F (approximately 93°C) above the ambient temperature; , and (2) individual thermocouples attached to non-heated surfaces of the gypsum panel that are not directly heated by 125° below ambient temperature.
Observe the number of times the gypsum panel can withstand heat before increasing by 0.0°F (approximately 52°C).

203°F (95°
C), fracture occurred at one point on the non-directly heated surface after 43 minutes and 40 seconds, and after 44 minutes at 162°d, fracture occurred at multiple points on the non-directly heated surface. Additionally, visual inspection revealed gaps of up to 0.635 cm at the edges of the directly heated surface of the gypsum panel and evidence of cracking or hair-like cracks in the directly heated surface. , 3.25% calcium sulfate hard-calcined anhydrite Quisker fiber filler such as Franklin Fiber and 3.2% wollastonite.
In the case of the gypsum panel of Experimental Example 2 containing 5j11', destruction at one point occurred in 45 minutes and 30 seconds of heating time, and destruction at multiple points occurred in 46 minutes and 12 seconds of heating time, and the time until destruction took longer. Ta. Moreover, the maximum deflection is 1.2 by visual confirmation.
70 cm, maximum gap 0.159e.

A large - crack was observed along the - stud.

As is clear from the above, the gypsum composition according to the present invention is extremely useful as a gypsum wallboard, and it will be understood that the fire resistance of the entire facility constructed using this gypsum wallboard can be greatly improved. The gypsum formulations of the present invention are also applicable to the production of other products, such as those made using hardened gypsum cores obtained by mixing dry calcined gypsum formulations and water. Dry calcined gypsum plaster mixtures based on the gypsum formulations of the invention can thus be employed in plaster kettles of metal molds, in which case plaster as well as upper steel beams and corrosion protection materials etc. in which the plaster mixture is mixed with water can be used. It can be applied to surfaces or cast into partition blocks or ceiling tiles and ceiling panels to improve fire resistance.

[Brief explanation of drawings]

The figure shows the expansion and contraction curves obtained by a one hour fire test of two formulation samples according to the invention and a comparative reference sample. patent applicant

Claims (1)

[Claims] 1. Hardened gypsum solids from gypsum slurry and substantially 2 to 4
1. A gypsum board formulation suitable for forming the core of a gypsum board, consisting of 0 x calcium sulfate anhydrite and having a fire resistance of at least one hour according to at least a laboratory fire test. 2. A gypsum board formulation according to claim 1, wherein the anhydrite (2) is calcium sulfate anhydrite obtained from a natural ore. 3. The gypsum board composition according to claim 1, wherein the anhydrite (1) is calcined calcium sulfate anhydrite. 4. The gypsum board composition according to claim 3, wherein the calcined calcium sulfate anhydrite is granular calcium sulfate anhydrite. 5. The calcined calcium sulfate anhydrite is calcium sulfate anhydrite in the form of acicular fine fibers having an aspect ratio of length to diameter of more than 20:1. gypsum board compound. 6. The solid content of hardened gypsum includes substantially 1 to 10% by weight of calcium sulfate anhydrite..., substantially 1 to 5% by weight of vermiculite, and substantially 0.1 to 1% by weight of glass fiber. A gypsum board composition according to claim 1, comprising: Claim 1, wherein the solid content of Z hardened gypsum contains substantially 1 to 10% of sulfuric acid anhydrite; and substantially 1 to 5% of vermiculite. gypsum board compound. 8. Equipped with a core made of hardened gypsum and a cover sheet covering the core, the core is substantially made of calcium sulfate anhydrite, which retains its bonding properties and prevents shrinkage even after being exposed to fire heat for 60 minutes. A fire-resistant gypsum board product containing 2 to 40% by weight of 9. A patent in which the core contains substantially 0.1 to 1 weight X of glass fiber and substantially 1 to 5 weight X material selected from the group consisting of non-expandable vermiculite and wollastonite. A gypsum board product according to claim 8. 10. calcium sulfate hemihydrate, substantially 1 to 10% by weight of calcium sulfate anhydrite, and substantially 01 selected from the group consisting of glass fiber, non-expandable vermiculite, wollastonite and mixtures thereof. ~5% by weight of the material.