JPH02243549A - Production of molded plate of gypsum - Google Patents

Abstract

PURPOSE:To obtain molded plates having uniform dispersibility of fibers and improved surface smoothness by blending anhydrous gypsum of II type with a considerable wet volume of fibers, mixing the blend with a curing promoter, thickening agent and water and extrusion molding. CONSTITUTION:30-98wt.% anhydrous gypsum of II type and 2-10p wt.% pulp having 350-50ml wet volume as main components are blended with a curing promoter, a thickening agent and water. Or the pulp is replaced with 0.5-2.0wt.% pulp having 600-350ml wet volume. The blended raw material is extrusion molded and hardened. Consequently, molded plates free from defects such as cracking, clicking, chipping, etc., can be produced.

Description

[Detailed description of the invention] a. Industrial application field The present invention is directed to (1) extrusion molding of a kneaded material mainly composed of type water gypsum, pulp, etc., dispersion of matrix and fibers, reinforcing effect, and molded product. This invention relates to a method for manufacturing a gypsum molded plate with improved surface smoothness.

b. Prior Art Type ■ Gypsum temporary manufactured by extrusion using water gypsum as the main raw material is disclosed in, for example, Japanese Patent Publication No. 51-27693, Japanese Patent Publication No. 54-17770, etc., and is used for extrusion molded products. Examples of the fiber include asbestos, glass fiber, rock wool inorganic fiber, and vinyl chloride fiber.

In extrusion molding, asbestos is an effective reinforcing fiber in all aspects such as strength and surface smoothness, but asbestos pollution has made its use difficult. Amorphous fibers such as glass fiber and rock wool have the disadvantage that they break during kneading and extrusion, making it difficult to obtain an effective reinforcing effect. In addition, synthetic fibers have strong intertwining and poor dispersibility, making it impossible to obtain surface smoothness, resulting in non-uniform molded plates, no effective reinforcing effect, and extremely brittle properties. Ta.

As a non-asbestos extrusion molding technology using a cement matrix, for example, Japanese Patent Application Laid-Open No. 55-51748
No., JP-A-60-137859, JP-A-61-174
No. 159, No. 62-46941, etc. have been proposed.

These improvement methods include combinations of alkali-resistant glass fibers and cellulose fibers, reinforcing fibers and magnesium silicate chlorite, wire fibers and sepiolite, carbon fibers and pulp fibers, etc. Through these improvements, non-asbestos compounds can be achieved. It is said that extrusion molding is now possible, and the same shape retention and strength as with asbestos can be obtained.

However, it has the disadvantage that the extrusion load increases, making extrusion molding less efficient.Depending on the amount of fibers, the fibers may become entangled with each other and form a fiber ball, making it impossible to mold, or the fibers may have poor dispersibility, resulting in poor strength. In particular, the surface of the product becomes uneven, and the surface smoothness cannot be obtained, so that it has not yet been perfected in terms of practicality.

Problems to be solved by the invention
It is required to have excellent surface smoothness.

The inventors of the present invention aim to: - improve the brittleness of the gypsum board by blending a considerable amount of fiber into type anhydrous gypsum, and obtain an effective reinforcing effect; - maintain uniform dispersion of fibers during extrusion molding;
Improving surface smoothness and ■Maintaining uniform dispersion of fibers during extrusion molding, preventing cracking even when processed by nailing, sawing, etc.

The purpose of this research was to obtain a molded plate that does not have defects such as punching and chipping.

d. Means to solve the problem As a result, ■ degree anhydrous gypsum and wet volume 350
The present invention was completed based on the knowledge that the objective could be achieved by extrusion molding of ~50 ml of a material whose main raw material is pulp.

That is, the gist of the present invention is to prepare pulp with 30-98% by weight of anhydrous gypsum and 2-10% by weight of pulp with a wet volume of 350-50ml, or 0.5-2% of pulp with a wet volume of 600-350mA. .0
The main component is pulp substituted by % by weight, and if necessary, 0 to 68% by weight of amorphous filler and 0 to 2% of other reinforcing fibers.
% by weight, and then kneading, extrusion molding, and curing the raw materials with a curing accelerator and a thickener added by external machining.

As the above-mentioned type 1 anhydrous gypsum, a fired product of dihydrate gypsum or type 2 type aqueous gypsum produced as a by-product during the production of hydrofluoric acid is used. ■The blending ratio of anhydrous gypsum is 30 to 98% by weight; if it exceeds 98% by weight, the fiber reinforcement effect and flexibility as a material cannot be expected, and if it is less than the lower limit of 30% by weight, the gypsum will completely disappear. Even when hydrated, the effect of fiber composite cannot be obtained due to insufficient amount of binder.

Pulp is used to improve the reinforcing effect, dispersibility, surface smoothness, and processability.

The amount of pulp is 2 to 10% by weight, and if it is less than 2% by weight, it will not be effective as a binder for the matrix, and improvements in moldability, reinforcing effect, and cutting/processability cannot be expected. If it exceeds 10% by weight, pulp dispersion during molding will be poor, it will be difficult to obtain material homogeneity and surface smoothness, and nonflammability will not be obtained as a building material.

Pulp can be crushed using hammer mills, impeller breaker disintegrators, bin mills, attrition mills, disc refiners, cone refiners, canter mills, rotary knife cuffter mills, centrifugal mills, super micron mills, pulverizers, turbo mills, etc. It can be obtained by dry defibration using a single machine or a combination of machines.

The wet volume of the pulp is 350-50 ml, preferably 300-50 ml! It is. This is 3
Not only when using 50-50 ml of pulp alone, but also 600-350 aa j! The same holds true when pulps of

If the wet volume of the pulp exceeds 350ml, the dispersibility of the fibers will be poor, resulting in a decrease in strength, and the surface will become uneven, making it impossible to obtain surface smoothness. Another 50m
j! If it is less than that, the fibers are too short and a sufficient reinforcing effect cannot be obtained.

Wet volume 600 to further enhance the reinforcing effect
~350 Pa1 pulp may be replaced by 0.5 to 2.0% by weight, but replacement of 2.0% by weight or more is not preferable from the viewpoint of fiber dispersibility and surface smoothness. In this case, the pulp may be defibrated by either dry or wet processing, but dry defibration is preferable in terms of moisture management.
Wet volume is 350 to 50 seconds. One item can be dry defibrated at the same time.

Here, the wet volume is the value obtained by dispersing 2 g of fibers in water 11 and measuring the settling volume of the pulp in a 1 liter measuring cylinder.

The fiber length distribution of the pulp used was that of papermaking pulp (TAPP
r Method T233) or the asbestos sieve content is determined by the test method (Qubeec Asbestos
Mining＾5sociation C-1-74)
Bauer-MacNesoto sieve content was measured using a testing machine in accordance with .

In the case of pulp with a wet volume of 350 to 50 ml, the amount of residue after sieving is 10
% or less, 500μ or more is 10% or more, 250μ or more is 2
It is 0% or more. It is preferable that the particle size is the same even when pulp is mixed. Furthermore, the wet volume is 600.
~350m1 J, the amount of sieve remaining is:
2360μ or more is 30% or less, 500μ or more is 40% or more, and 250μ or more is 50% or more.

In addition, the Canadian standard freeness (C5F) of pulp is 7
It is about 70-200ml. This value hardly changes depending on the dry defibration treatment.

Normally, pulp is subjected to wet defibration treatment using a pulper, disc refiner, or the like. In the case of wet defibration treatment, the wet volume value remains almost unchanged at around 500 ml depending on the pulp, but when the fibers become fibrillated, the standard freeness decreases and the Canadian standard freeness is 200 to 100+.
It becomes about mβ or less. Therefore, the pulp amount is 2 to 3% by weight.
Even if it is blended, the dispersibility of the molded product is poor, and the moldability and surface smoothness are poor. Therefore, wet defibration processing requires a large amount of energy for defibration processing and has poor dispersibility, so it is not suitable as a fiber for extrusion molding.

As reinforcing fibers other than pulp, glass fiber, carbon fiber,
Inorganic fibers such as rock wool and synthetic fibers such as polyamide, polypropylene, polyvinyl alcohol (vinylon), polyester, polyethylene acrylic, etc. may be used in combination with the pulp.The length of the fibers is 6fi or less, preferably 3fi or less. be. The amount of reinforcing fiber is 0-2% by weight
and is preferably 1% or less. Reinforcing fibers have strong fiber entanglement, and if the amount is more than 2%, fiber balls will occur, the dispersibility will be poor, and surface smoothness will not be obtained.

Alkali adjustment agent and fine powder as inorganic filler.

A filler or the like is used.

Slaked lime and cement are used as alkaline adjusting agents.

Examples include water glass, sodium aluminate, potassium aluminate, and the like. The alkaline adjustment agent is the pH of the gypsum mixture.
It is suitably blended in a range of about 0 to 3% by weight in order to make the range of 8.0 to 12.0.

Fine powders include diatomaceous earth, zeolite, silica dust, and clays such as kaolin and pyrophyllite.

Filling materials include powders such as limestone, silica, slag, fly ash, dihydrate gypsum, serpentine, talc, mica, and wollastonite, lightweight materials such as perlite, vermiculite, and shirasu balloon, and crushed products (scrap) of defective products. is used.

■As a hardening accelerator for type water gypsum, KtSOa=N
atSOe+Mg5Oa+Zn5On, Fe5On+C
Sulfates and double salts such as u5On+A it z(SOe)s, e.g. KA It (Sot) z·12H2O
NaAj! (SOe)x' 12HzO, NHeA
j! (SOe)i' Alums such as 12nzo, NaCit, CaCj! Chlorides such as z+MgCIt z, acid hydrogen salts such as NaH5Ot, H3O, etc., N
aN0. , NH, NOff, KNO3, and other general-purpose nitrates can be used alone or in combination. The amount of the hardening accelerator is 0.2 to 2.0 parts by weight based on type (1) water plaster.

As the thickener, commonly used water-soluble polymer agents such as ethylene oxide polymer, acrylamide polymer, polyvinyl alcohol, methyl cellulose, and hydroxyethyl cellulose are used. The blending amount is 0 for the total amount
．． It is about 1 to 2.0 parts by weight.

The manufacturing process in the present invention is as follows.

Add the necessary water to the raw material mixture and knead it using a kneading machine such as a Nigu, Eirich type mixer, or vacuum soil 'am to ensure uniform dispersion, then mold it using an extrusion molding machine, and cure the molded plate to hydrate it. Let it harden. After curing, the molded plate is dried if necessary and cut into standard dimensions to produce products. The density of the resulting gypsum molded plate is approximately 1.3 to 1.9 aJ/g.

e. Effect Type: In a method of kneading and extruding hydrogypsum, TA fibers, hardening accelerators, thickeners and water, a predetermined fiber length can be achieved by using pulp with a wet volume of 350 to 50111 as the fibers. Even if more than a certain amount of distributed pulp is mixed, entanglement is eliminated during kneading, uniform dispersion is obtained, and the pulp is fully effective as a binder for the matrix, improving moldability, shape retention, and reinforcement. The effect was obtained and the surface smoothness was improved.

If wet defibration treatment and dry defibration treatment are insufficient,
Even if the amount of pulp is small, the fibers are highly entangled,
This results in formation of fiber balls with poor dispersibility, poor reinforcing effect, and poor surface smoothness.

f. Examples Examples 1 to 14, Comparative Examples 1 to 9 The waste paper was subjected to dry defibration treatment using a hammer mill and a disintegrator to obtain pulp with a predetermined particle size. Using these pulps, a predetermined raw material composition was dry mixed in an Eirich type mixer at high speed for 1 minute, and then mixed in a kneader.
Add the water necessary for molding and knead for 10 minutes to ensure uniform dispersion.Then, the kneaded material is molded using a screw-type vacuum extrusion molding machine to a thickness of 10 mm and a width of 200 mm.The resulting molded plate is
It was cured for one week at a temperature of 0°C ± 2deg for hydration hardening. After curing, the molded plate was dried at 60°C±3deg, cut into standard dimensions, and tested.

Comparative examples were also molded and tested in the same manner.

The amount of water and methylcellulose were added by external cutting to the anhydrous gypsum, fibers, and inorganic fillers, and the hardening accelerator was added to the plaster by external cutting.

Table 1 shows the properties of the pulp in Examples 1 to 14.

The formulation and the property test results of the molded plate are shown.

Table 2 shows the properties of pulp in Comparative Examples 1 to 9.

The formulation and the property test results of the molded plate are shown.

The raw materials used, test methods, etc. in Examples and Comparative Examples are as follows:
It is as follows.

Tan-l-mutual and H-type water gypsum: Anhydrous gypsum, a by-product during hydrofluoric acid production, powder level 5210 cj/g, pH 3, made by Nippon Electric Glass Co., Ltd. Chi1 Fubu F Stran F6 mm Made by Nirirale Vinylon tan
6u: Made by Siegrite, powder degree 3.6300d1g:
Manufactured by Okutama Kogyo: Manufactured by Okutama Kogyo: Reagent 1st grade methylcellulose: Shin-Etsu Chemical Himeto rt-no 905
) 1-15000 glass fiber vinylon fiber zeolite slaked lime limestone potassium sulfate sip] 18602 r asbestos”.

Undried pulp sample (dry test) Fee 2. OOg equivalent) to water Il Add and mix with high speed mixer for 15 seconds. Stir for a while, 1 liter scalpel Pour into cylinder, 2 o'clock Fiber length distribution Canada standard freeness specific gravity Measure the sedimentation volume after the interval.

: TAPPr Method T233 and Qubeec Asbestos Mining Association
on) Based on the asbestos test method of C-1-74, using a Bauer McNeLt sieve tester, thoroughly stir the undried pulp sample (equivalent to 10.00 g of dry sample) with 500 m of water II. Loosen it, supply water amount 51/I! lin, sieve 2360°11B0.50
Measurement was carried out for 20 minutes through a 0.250μ sieve, and the amount remaining on each sieve (dried at 105°C ± 26eg for 24 hours) was expressed as a percentage of the sample amount.

: According to "JIS P8) 21 r pulp bark test method".

: Based on JTS A3418 r asbestos cement calcium silicate plate, based on bending strength, length change rate, impact test, hydration rate, dispersion property, (Abbreviation for bulk specific gravity in JIS): Based on JIS A3418 r asbestos cement calcium silicate board. .

: Compliant with JIS A3418 r asbestos cement calcium silicate board J.

: Based on the Charpy impact strength test of JTS K6911 r General Test Methods for Thermosetting Plastics.

;Dry the ground sample at 45°C; Calcinate this at 200℃, Plaster placement based on weight loss Measure the hydration rate for the mixture.

: Dispersion of fibers, degree of entanglement Judgment is made by visual observation of the kneaded material.

■ Good ○ Good condition △ Small fiber poles present in some parts Surface smoothness workability × Fiber balls present throughout: Visually observe the test piece 20 x 30 cam to determine the state of surface irregularities.

■ Good ○ Good condition △　There are small irregularities in some parts. X Large unevenness throughout : The test piece is cut using a nailer or cutting machine. Processed, cracked, punched, and chipped. Check for defects such as cracking. Determine the condition.

◎ Good○ Good condition △ Small defects × Large defects By blending a considerable amount of Nonolube with a wet volume of 350 to 50 ml, a new high-quality gypsum molded plate, which has never been seen before, was obtained as described below.

(1) Wet volume 350-50cm! By blending a considerable amount of pulp, entanglement was eliminated during kneading, the dispersibility was improved, a better reinforcing effect was obtained, and the surface smoothness was improved.

(2) Wet volume 350-50ml,
By mixing pulp with a wet volume of 600 to 350 ml, there was no difference in surface smoothness, but the reinforcing effect was improved and a high-quality gypsum molded plate was obtained.

(3) Wet volume l350~50m j! By blending a considerable amount of pulp, the dispersibility and surface smoothness were improved, and the amount of thickened pulp could be reduced.

(4) Wet volume: 350-50 m By blending a considerable amount of 12 pulp to improve dispersibility, the reinforcing effect was enhanced and the amount of curing accelerator could be reduced.

(5) ■ Type water gypsum has fine grain size, soft hardness, and low Young's modulus of hardened material, so it has a high composite effect with pulp, and has excellent quality in bending strength, impact strength, and length change rate. A noncombustible material was obtained, which was free from efflorescence, had excellent surface smoothness, and had excellent handling properties such as cutting, processing, and assembly.

Claims (2)

[Claims] (1) A hardening accelerator, thickener and water are added to a raw material mainly consisting of 30-98% by weight of type II anhydrous gypsum and 2-10% by weight of pulp with a wet volume of 350-50ml, followed by extrusion molding. , a method for producing a gypsum molded board, characterized by curing it. (2) Wet volume of the above pulp 600-350
The method for manufacturing a gypsum molded board according to claim 1, characterized in that 0.5 to 2.0% by weight of pulp is replaced with ml of pulp.