JPH02199046A - Fiber reinforced cement molded article - Google Patents

Abstract

PURPOSE:To obtain a fiber reinforced cement molded article having excellent strength by curing a cement molded article containing a sheath-core type composite fiber consisting of polymethylpentene sheath and PP core used as a reinforced fiber in an autoclave at high temperature. CONSTITUTION:A sheath-core type composite fiber each using PP as a core, polymethylpentene as a sheath covering the core is prepared. The composite fiber has preferably 6-30 denier, 3-30mm length and 50-1000 aspect ratio. Then cement slurry is blended with the above-mentioned composite fiber and the blend is molded by ordinary paper making, extrusion molding, etc. In this time, blending of the composite fiber is preferably carried out at an amount of 0.2-5wt.% based on the solid content in cement slurry. Then the above-mentioned composite fiber is cured at 150-170 deg.C to provide the aimed fiber reinforced cement. Furthermore, cross section of the sheath in the above-mentioned composite fiber is preferably 40-80%. The above-mentioned molded article can be cured at high temperature and has excellent flexural strength, impact strength and nail hammering characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cement molded body, particularly a fiber-reinforced cement molded body cured at high temperatures and having improved strength.

[Conventional technology]

Conventionally, various cement molded bodies have been used in various industrial fields, especially in the vat-dying industry, and various E fibers have been used as reinforcing materials to improve the strength of such cement molded bodies. ing.

Asbestos, for example, is known as a typical fiber-reinforcing material, and it has been widely used because it is inexpensive, nonflammable, and has excellent heat and alkali resistance. However, asbestos The use of asbestos is undesirable because it is harmful to humans.Therefore, the use of various inorganic and synthetic fibers has been proposed as an alternative to asbestos.

For example, JP-A-49-98424, JP-A-49-104
No. 917, JP-A-49-104918, JP-A-61-
86452, JP-A No. 62-171952, etc., glass fiber, polyester Z fiber, vinylon fiber 1 polypropylene fiber, aromatic polyamide fiber f (Lw acrylic a!
The use of fibers is taught.

Using these reinforcing fibers, conventional methods such as paper forming,
Cement molded bodies formed by extrusion molding or cast molding are cured to improve their strength. This curing includes natural curing and autoclave curing,
Natural curing requires long-term curing of 20 days or more and is not efficient for industrial production. For this reason, autoclave curing, which is forced curing, is no longer used as an alternative.

In this autoclave curing, the various reinforcing fibers described above in a highly alkaline cement matrix are typically treated at temperatures of 80°C to 160°C for 16 to 48 hours. In particular, depending on the type of cement 1', for example, in the case of calcium silicate cement, curing at a high temperature of 180 DEG C. to 200 DEG C. is required in order to obtain the desired strength.

It is generally known that the higher the curing temperature of a cement compact, the greater its strength, and it is also known that the curing time can be shortened. For this reason, recently the autoclave curing temperature has been increased to 170℃.
-210°C and a curing time of 12 to 18 hours are being used to improve productivity and increase the strength of cement molded bodies.

[Problem to be solved by the invention]

However, under the alkaline conditions of cement matrix and curing at the high temperatures mentioned above, polyester 'a' fibers, vinylon mat, polyamide fibers, and acrylic fibers undergo chemical changes such as decomposition, become brittle, and lose their function as reinforcing fibers. It will be lost.

In addition to normal glass fibers, even alkali-resistant glass fibers become brittle and lose or significantly reduce their function as reinforcing fibers when cured at the high temperatures mentioned above. Polymethylpentene fiber is known as a fiber that can withstand high temperatures, but this fiber is very expensive and is not practical for manufacturing ordinary cement molded bodies, and polymethylpentene is generally soft. , are not sufficient as reinforcing fibers for cement molded bodies.

Polypropylene fibers have excellent alkali resistance and are preferred as reinforcing transverse fibers for cement molded bodies, but polypropylene can usually only withstand temperatures up to 170°C, and beyond this temperature even polypropylene fibers lose their strength. ability will be lost.

Accordingly, an object of the present invention is to provide a cement molded body having excellent strength when cured at a high temperature of 170 to 210°C.

[Means to solve the problem]

In the present invention, polymethylpentene was used as reinforcing I 177 in a steel molded cement molded t-do which was molded and then autoclaved. It is a cement molded body.

The reinforcing fibers used to form the cement molded body of the present invention are:
Polypropylene is used for the core, and polymethylpentene is used for the sheath that covers it.

The TL manufacturing method of such sheath-core type composite fibers is a conventionally known sheath-core type composite fiber! Manufactured according to anyone's manufacturing method, it can be stretched.

As for the polymethylpentene used in the above sheath and L”C,
Homopolymers of 4-methylpentene-1 or other copolymerizable monopolymers, such as ethylene, propylene, butene-1, hemocene-1°octene-11decene-11
Tetradecene-1゜octadecene-1 etc. with 2 to 2 carbon atoms
Any copolymer of 0, preferably 3 to 5 α-olefins can be used. In the case of a copolymer, it is preferable that it contains 4-methylpentene-1 in an amount of usually 90 mol% or more. It takes 4
- Homopolymers and copolymers of methylpentene-1 usually have a melting point of 230°C to 240°C and can withstand the curing temperatures described below, for example temperatures of 170°C to 210°C,
It can also withstand the alkalinity of the cement matrix.

In addition, the polypropylene used as the core of the composite powder in the present invention can be a known polypropylene.

In the composite fiber used in the present invention, the above-mentioned polymethylpentene should occupy at least 40% of its cross-sectional area. If this cross-sectional area is less than 40%, the polymethylpentene strength will be too small, and the core polypropylene may be exposed, making it difficult to obtain a complete sheath-core type composite fiber, which is undesirable. The higher the proportion, the better the heat resistance of the composite and fiber, but the proportion of the polypropylene component becomes too small.
It is difficult to manufacture composite fibers, and polymethylpentene resin is expensive, making it uneconomical, so it is usually 80%.
It is best to do so by.

The above-mentioned composite fibers are similar to commonly used fibers, with 6 to 3
0 denier, length 3-300, asbec Ht, 50-1
000 is recommended.

As the cement used in the present invention, any cement can be used, such as ordinary Portland cement, special Portland cement, alumina cement, blast furnace slag cement, etc. In particular, calcium silicate cement, which generally requires a high curing temperature, can also be used.

In producing the cement molded article of the present invention, the composite fiber according to the present invention described above is mixed with a cement slurry, and the mixture is molded by ordinary paper forming, Koriyama molding, or cast molding. At this time, the composite fibers are preferably used in a usual proportion of <0.2 to smgk% based on the total solid content in the cement slurry.

After being molded in the manner described above, the molded body is then cured in an autoclave. Of course, autoclave curing can be carried out at a temperature of 160°C to 170°C for 8 to 15 hours, as is normally done, but by using the composite fiber of the present invention, curing can be carried out at a high temperature of 170°C to 210°C for 1 hour.
Curing conditions of 2 to 18 hours can be used.

[Effect]

The cement molded article of the present invention uses a sheath-core type composite fiber with a polymethylpentene sheath and L and a polypropylene core as reinforcing fibers, so polypropylene fibers alone will melt and cannot perform the reinforcing function. Even at high curing temperatures of 170 to 210 degrees Celsius,
Because it has a polymethylpentene sheath, the polypropylene core will not melt and the polymethylpentene will leach out of the rock and cause so-called slip-through. Therefore, the polypropylene fibers have the effect of fully exhibiting their function as reinforcing fibers in the finished cement molded product after curing treatment. So-C The curing temperature can be set to high <L, and the curing time can be shortened.

〔Example〕

Examples of manufacturing the sheath-core composite fibers used in the cement molded product of the present invention and examples of the cement molded product are shown below.

Production example 1 Melt flow rate 50J710 minutes (weighted 21699.
270℃), polymethylpentene (PN) with a melting point of 240℃
P) with the sheath component and L, melt flow rate 20Ii/1
0 minutes (weighted 2169 II.

230℃), polypropylene (PP) at point i at 163℃, core component and L, composite ratio (cross-sectional area ratio, PP/PM
A concentric sheath-core type composite fiber having a fineness of 42 denier in an unstretched state was obtained by melt spinning L at a spinning temperature of 280° C. and a discharge rate of 310 cd/min from a spinneret with a diameter of 50150 and 120 holes.

This fiber was then dry-stretched 7 times at 140°C, with a fineness of 6,
A composite fiber of 6 denier was obtained. The dry strength of this fiber (g/
D ), dry elongation (%) and Young's modulus (kg/d) are shown in Table 1.
Shown below.

An alkali resistance test of the above-mentioned fibers was carried out as follows.

Close one end of a stainless steel pipe with an inner diameter of 20mm and a length of 150mm with a plug, and insert the bellows 1 made as described above into this pipe.
o! A supernatant liquid of cement-containing water prepared by mixing 1 part by weight of cement and 9 parts by weight of water was added, and the opening was closed with a plug to prevent any air bubbles from entering. The two test samples thus prepared were each placed in an electric dryer at 180°C for 16 hours or at 200°C for 16 hours.
Ta.

After cooling, each vertebra sample was taken out, and the dry strength (9/D), dry elongation (%), and fiber shape of these jIL fiber samples were measured. Table 1 shows the results.

Production Example 2 An undrawn concentric sheath-core composite fiber with a fineness of 27 denier was produced in the same manner as in Production Example 1, and this fiber was then stretched 4.5 times in warm water at 95°C to produce a composite fiber with a fineness of 6.6 denier. I gained wisdom. Table 1 shows the dry strength, dry elongation, and Young's modulus of this fiber.
Shown below.

This fiber was also subjected to an alkali resistance test as described in Production Example 1, and the results are shown in Table 1.

Production Examples 3 to 4 According to the method of Production Example 1, the undrawn yarns shown in Table 1 were made at the composite ratios shown in Table 1, and these fibers were dry-stretched 7 times in the same manner as Production Example 1 to give 11.6 Denny/I/
(Production Example 3) and 7.0 denier (!J1 Production Example 4) drawn composite fibers were produced, and the dry strength, dry elongation, and Young's modulus of these fibers were measured. The results are shown in Table 1.

As described in Production Example 1, each of these fibers has a resistance of 7/
Table 1 shows the results of the L/potash test.

Comparative Production Example 1 12 In Production Example 1, melt flow rate 40,9710 min (weighted 2169.9, 26 min) was used instead of polypropylene.
Using polyethylene terephthalate (PET) (0°C) as the core component and the PNP of Actual Drawing Example 1 as the sheath component -C4! In the same manner as Example 1, the composite ratio was 50150,
An undrawn concentric sheath-core type conjugate fiber of 36 denier was produced, and then dry-rolled 6 times at 140°C to obtain a conjugate fiber of 9.6 denier. Table 1 shows the dry strength, dry strength, and Young's modulus of this fiber.

Table 1 shows the results of an alkali resistance test of %1 performed on this fiber as described in Example 1.

Comparative Production (Reference) Examples 2 to 3 For reference, the results of dry strength, dry elongation, and alkali resistance tests for polypropylene (PP) and rayon shown in Table 1 below are also shown in Table 1.

(Qin) Maintains O appearance: × Does not maintain fiber shape: Core is straw-shaped Example l 20 parts by weight of Portland cement, 31 parts by weight of silica sand, 31 parts by weight of quicklime, barley) 15Ii parts by weight, 22111 parts by valve (NBKP) and 1 part by weight of the sheath-core composite fiber made in Production Example 1 were mixed in L. [9 parts by weight of water was added to 1 part by weight of this mixture, and a small amount of A flocculant was added and mixed to make a papermaking solution.

Using this papermaking liquid, form a cement molded body by papermaking L, leave it at room temperature for 24 hours to solidify, and then
Autoclave curing was performed at 5°C for 16 hours. The obtained molded body was evaluated for bending strength, impact strength, and nailing characteristics. These results are shown in Table 2.

Examples 2 to 3 A cement molded body was produced in the same manner as in Example 1, except that the fibers of Production Example 3 (Example 2) or 4 (Example 3) were used as the sheath-core composite fibers, respectively. The construction, bending strength, f19 strength, and nailing characteristics were evaluated. Table 2 shows the results.
Shown below.

Comparative Examples 1 to 2 In Example 1 [, 1 in place of the sheath-core composite fiber
A cement molded body was made in the same manner as in Example 1 except that 3101 parts of the composite fiber of Comparative Production Example 1 (Comparative Example 1) or rayon fiber (Comparative Example 2) was used, and the bending strength, @impact strength,
The nailing characteristics were evaluated. The results are shown in Table 2.

Comparative Example 3 Example IK#, no reinforcing fibers, and 2 valves.
A cement molded body was made in the same manner as in Example 1 using 31 parts instead of i parts, and its bending strength, impact strength, and nailing characteristics were evaluated.

The results are shown in Table 2.

Comparative example 4 Portland cement) 20 @ melon part, silica sand 25 part,
Same as Example 1 (&
Cement molded bodies were made and their bending strength, impact strength, and nailing properties were evaluated. The results are shown in Table 2.

The bending strength, impact strength and nailing properties were measured as follows.

Bending strength: A cement molded plate with a length of 120 mm, a thickness of 5 mm, and a width of 50 mm is placed on a fulcrum with a span interval of 70 mm L, JIS A 1.
It was measured according to the method of No. 408 (9t/cd per unit).

Impact strength: Method A: Conducted according to JIS B 7722 (Charpy impact test method) with a thickness of 5 fl (unit: 9 f/α).

Method: JIS B 7723 (Izotsu) f! iff test method) (unit: 41f)
/ faith).

Nailing characteristics: Corner 3 of cement molded body 1 with a thickness of 5 tl as shown in Fig. 1
A nail with a diameter of 2.6 mm was nailed to the diagonal of corner 3 of the rectangle taken along both sides from
.

〔Effect of the invention〕

As is clear from the data in Tables 1 and 2 above, the cement molded product using composite fibers according to the present invention can be cured at high temperatures and has excellent bending strength, impact strength, and nailing properties.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of nailing characteristics measurement. 1-m-cement molded body, 2-11 nails. hand Continued Supplementary Positive book No. figure 2゜ name of invention fiber reinforced cement molded body 3゜ person who makes corrections Relationship with the incident

Claims (1)

[Claims] 1. In a fiber-reinforced cement molded article that is molded and then cured in an autoclave, a sheath-core type composite fiber having polymethylpentene as the sheath and L and polypropylene as the core is used as the reinforcing fiber. Cement molded body. 2. The cement molded article according to claim 1, wherein polymethylpentene occupies at least 40% of the cross-sectional area of the composite fiber.