JPH01122943A - Polypropylene film fiber-reinforced cement formed product - Google Patents

Abstract

PURPOSE:To obtain a PP fiber-reinforced cement formed article having improved dispersibility and strength, by blending trunk-shaped and chopped strand filament type PP film fiber having each specified average fineness of trunk fiber and aspect ratio into a cement matrix and forming the blend. CONSTITUTION:PP film having 25-35mu thickness is cleaved and divided and cut to provide a trunk shaped and chopped strand filament type PP film fiber having 40-60 denier average fineness of trunk fiber and 40-200 aspect ratio. As the above-mentioned fiber, the trunk fiber having 3-18mm length is preferably used. Then the PP film fiber is blended with a cement matrix as usual to form the cement formed product. The blend of the PP film fiber is carried out in a blend amount of 0.3-5.0vol.% based on total amount of the PP film fiber and cement matrix.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to cement moldings reinforced with trunk-branch shaped chopped filament type polypropylene (PP) film fibers, particularly by papermaking, extrusion or cast molding methods. This applies to manufactured cement moldings with a thickness of 20 mm or less.

[Conventional technology]

Conventionally, Ppm fibers have been widely used as reinforcing fibers for cement moldings that are thinner than 20 m+a thick, for example, but the PP fibers that have been used conventionally have circular or nearly circular cross sections, and may These fibers have a smooth surface and usually have an aspect ratio of 300 or more.
(See Publication No. 129861).

Because such fibers have a smooth surface, they easily slip off during the formation of a cement molding, and because of their large aspect ratio, it is very difficult to uniformly disperse them in the cement matrix.

As an alternative to such conventional PPv4 fibers, axially stretched PP films can be fibrillated.
However, chopped filament-type PP film fibers in the form of trunks and branches, in which the trunk fibers are cut into appropriate lengths, have been reported (see British Patent No. 1130612). Furthermore, chopped filament type PP film fibers made by adding a surfactant have been reported (U.S. Patent No. 4).
261754 and 4310475).

However, the film fibers described in UK Patent No. 1,130,612 do not have sufficient adhesion to the cement matrix, and the film fibers described in US Pat. However, the film fibers described in these documents all have a main fiber fineness of 2 to 35.
dtax (1.8 to 31.5 deniers), and the aspect ratio is also 300 or more. A major feature of such film fibers is the presence of split ends (fray) on the side surfaces, and these split ends exhibit a great effect as reinforcing fibers. Since the aspect ratio is more than 300, it is difficult to uniformly disperse it in the cement matrix, and there are problems with its dispersibility, and it is necessary to use special admixtures or dispersants such as methyl cellulose or silicone oil. It is difficult to fully utilize the features of the film fibers mentioned above. That is, the strengths of cement molded products made using film fibers having such fineness and aspect ratio vary widely, and it is difficult to obtain cement molded products with uniform strength, especially in the case of thin cement molded products.

[Problem that the invention seeks to solve]

The reinforcing effect of fibers on cement molded articles generally depends on the physical and chemical properties of the fibers themselves (e.g., strength and elongation, elastic modulus, adhesion to the cement matrix, alkali resistance), but it also depends on the overall strength of the cement matrix. It is known that it is highly dependent on the volume fraction of fibers in the volume, but even at the same volume fraction, the uniformity of fiber dispersion in the cement matrix and the size of the total surface area of the dispersed TA fibers are significantly affected. 0 Therefore, in order to increase the total surface area of fibers at the same volume fraction and strengthen the fibers, it is generally accepted that the aspect ratio of the fibers used is increased. Fibers with more than 300 are used.

However, the larger the aspect ratio, the more easily the fibers become entangled, and the more likely it is that lumps or fiber balls are generated during the mixing process with the cement matrix, resulting in uneven dispersion in the cement matrix. Even with a small volume fraction, a sufficient strengthening effect on the cement molded product cannot be obtained, and furthermore, there has been a problem that variations in the various strengths of the cement molded product become large. Particularly in a cement molded product having a small thickness, the formation and presence of the above-mentioned 7 eyeper balls deteriorates the various strengths of the cement molded product.

The purpose of the present invention is to improve the shape, especially the fineness and aspect ratio, of chopped filament type PP film fibers in the trunk and branch shape when reinforcing thin cement molded products with a thickness of 20 mm or less, for example, with film fibers. By adjusting the content within an appropriate range, the above-mentioned dispersibility can be improved and the strength of the cement molded product can be improved.

[Means for solving problems]

The present invention uses chopped filament type PP as a reinforcing fiber in a trunk and branch shape, which has a shape characteristic of average fineness of trunk fiber: 40 to 60 denier, and aspect ratio of trunk fiber: 40 to 200.
It is a cement molded product made by blending film fibers with 0.3 to 5.0% by volume of cement. It can be made by manufacturing a PP film by a known method, highly hot stretching the film in the axial direction to form a film with a thickness of 25 to 35μ, which is split by passing it through a porcupine roller, and then cut. .

Methods for producing such fibers are themselves described in the UK and US patents mentioned above.

According to the present invention, the highly stretched film for making the above-mentioned chopped filament type PP film fibers having a trunk and branch shape has a cutting strength of 50 Kt/- or more and a cutting elongation of 8% or less and an elastic modulus of 120 ．． It is preferable to use a film having characteristics of OKf/- or more.

In the first place, when a load is applied to a cement molded product, the stress is transmitted to the reinforcing fibers through the cement matrix, but at this time, the cutting strength of the PP film fibers is 5.
If it is less than 0 kg/-, the cement molded product may break before it reaches the strength required for a cement molded product, especially a thin cement molded product, which is not preferable.

In addition, even if the cutting strength of the PP film fiber is 50 kg/- or more, if the cutting elongation exceeds 8%, the PP film fiber itself will elongate significantly even without cutting, so it will crack under a low load below the product strength. This is undesirable as it may actually lead to the destruction of the cement molded product.

Further, even if the cutting strength is 50 Kf/- or more and the cutting elongation is 8% or less, unless the elastic modulus is 1200 Kg/- or more, cracking in the initial stage under load will not be sufficiently prevented and the breaking strength of the molded product will not improve.

According to the present invention, it has the above-mentioned characteristics and has a thickness of 25 mm.
~35μ PP film is then passed through a Y-4 Yubain roller to split and split, and cut to obtain an average fineness of main fibers: 40
~60 denier Aspect ratio of trunk fiber: 40 to 200 A chopped filament type PP film fiber with a trunk and branch shape is made.

The length of the above-mentioned PP filament fibers may be set to the most suitable length for the purpose, usually 3 to 9 m for paper forming, preferably 3 to 151111 m for approximately 68% extrusion molding. Preferably, 6 to 18 m, preferably 12 to 15 cm, is used for a 9 to 12 W one-cast molding. For this reason, also in the present invention, it is preferable to use PP filament fibers whose main fibers have a length of 3 to 18 m.

Next, regarding the average fineness and aspect ratio of the main fibers, if the fibers have good dispersibility, generally the larger the aspect ratio, the higher the reinforcing performance.

However, in reality, the larger the aspect ratio, the worse the dispersibility, and as a result, the desired strength of a cement molded product made using it may not be obtained.

For this reason, if the fineness is less than 40 deniers and the aspect ratio exceeds 200, the fiber length will exceed 20m, making it impossible to obtain uniform dispersion with normal kneading. When it becomes smaller, the dispersion becomes better, but the reinforcing performance of the PP film fiber becomes inferior. Further, when the fineness is greater than 60 deniers and the aspect ratio is less than 40, the fiber length becomes 2 m or less, making it impossible to obtain substantial reinforcing performance.

Therefore, in the present invention, the fineness is 40 to 60 in relation to the fiber length.
Preferred ranges are denier and aspect ratio of 40 to 200.

According to the present invention, the above-mentioned chopped filament type PP film fibers having a trunk-branch shape are mixed with a cement matrix in a conventional manner to form a cement molded product. At this time, the PP film fibers are mixed in an amount of 0.3 to 5.0% by volume based on the total amount with the cement matrix. The compounding method can be carried out by a well-known method.

If the above-mentioned blending ratio is less than 0.3% by volume, no substantial reinforcing effect can be obtained, and if it is more than 5.0% by volume, dispersion becomes extremely difficult and the kneading time becomes long, which is not practical. Further, the completed cement molded product becomes porous, which may reduce the bending strength or dimensional stability of the cement molded product, which is undesirable.

The PP film fibers used in the present invention are preferably subjected to a corona discharge treatment according to a conventional method in the film state before being split and split as described above, since this improves the adhesion with the cement matrix.

Furthermore, when treated with a surfactant such as an anionic surfactant such as polyethylene glyfur alkyl ester after forming into PP film fibers, PP can be absorbed into the cement matrix.
This is preferred because it improves the dispersibility of film fibers.

According to the invention, paper molding, extrusion or casting methods can be used to produce cement moldings from the above-described mixture of PP film fibers and cement matrix.

In addition to the above-mentioned PP film fibers, additives commonly used in the production of cement moldings, such as cellulose fibers such as pulp, methyl cellulose, and sulfurizing agents such as Mighty M-150 (Kao products) may be added.

[Effect]

In thin cement moldings whose thickness is usually 20 cm or less,
When the above-mentioned chopped filament type PP film fibers of the present invention are used, the PP film fibers can be uniformly dispersed in the cement matrix in a short period of time by the usual pressing and mixing action. Further, during the rod mixing action, the PP filament Ham is re-cleaved and its surface area increases. This makes it possible to obtain cement molded products with extremely excellent strength properties.

〔Example〕

The present invention will be explained below with reference to Examples.

Chopped filament type P with trunk and branch shape for testing
Production of P film fiber General grade PP resin (M process: 3.0) is passed through a ring die of a normal extruder at a wetness of approximately 220°C.
The film was extruded by an inflation method with a blow ratio of 1:1, and after air cooling, it was uniaxially stretched 20 times through a hot air opening at 180°C, and then annealed through a hot air opening at 160°C to produce a film with a thickness of 30 μm.

Next, the surface of the above film was subjected to corona discharge treatment at a high voltage of 12KW, and the needle density was 170/C4.
The film was split and split by passing it through 1, 3, and 5 stages of porcupine rollers whose surface speed was 3 times, 5 times, and 7 times the film speed, and finally a polyoxyethylene glycol ester surfactant was applied. Afterwards, the lengths of the main fibers are 9m, 12m and 15m+ after cutting.
It was made into PP film fiber. The fineness and aspect ratio of each of the PP film fibers thus produced are shown in the table for each example. Note that as the surface speed and number of passes (number of stages) of the vorcupine muller increase, the degree of cleavage becomes finer.

Example 1 and Comparative Examples 1 to 3 The present Examples and Comparative Examples were carried out by a paper forming method.

The materials used are shown below.

Asbestos 5.4 2.25
2.4 valve 1.4
1.4 1.0 cement 114.7 3.3
34.8 micro silica 10.8
2.2 4.9 total 585.0
496.1 Using an experimental pulper with a capacity of approximately 5001, which is exactly the same type as the disintegrating machine (pulper) used in normal papermaking and molding methods, a rotor/stator: 0.
Under the conditions of 8 degrees, rotor rotation speed: a o o rpm, first, 450 to 4 parts water was put into a pulper, 2.7 parts of reinforcing fiber was mixed, and the mixture was stirred for 8 minutes. then 5, 4
Kg of asbestos and 1.4 kg of pulp were mixed and subsequently stirred for 7 minutes. Finally 114.7? Micro silica (9) was added to 1:10.8 of cement (1:10.8), and the mixture was further stirred for 5 minutes.

The slurry produced in this way was processed into a 6111mm thick experimental papermaking machine, which is exactly the same type as the commonly used Hachnik-type papermaking machine.
%width? A molded product (flat plate) of 2C11% and length 182C11 was formed.

At this time, the volume fraction of the reinforcing film fibers to the volume of the molded product was 2%. During this papermaking operation, slurry was circulated between the pulper and the papermaking tank.

After the molded product was naturally cured for 28 days, it was subjected to a physical property test.

Table 1 shows the test results for the cement molded product.

In Comparative Example 3 in Table 1, spun general pPm fibers with a fiber length of 6CIl+ were used.

Table 1 Strong fiber (7) 7X'' 70~60 215~12
5 50-40 300 specific bending strength (KII/cd)” 256 24
2 224 238 (1): 7 The number of eyeball balls (clumps of fibers) was measured as follows.

The raw board immediately after cutting is 316w x 316tm (0,1
rye) and placed in a box of the same size with a 10-mesh screen on the bottom, and while gently vibrating in water, the cement and microsilica were poured out into the water, leaving nothing on the screen. The fiber-asbestos-bulb sheet was visually observed, the number of fiber balls was counted, and the number was calculated per 1 i.

(2): For bending strength, a test piece cut into a size of 5 am x 25 Ca1 was used.

(3): A test piece cut into a size of 4 am x 8 Ca+ was used for the impact test.

Example 2 and Comparative Examples 4 to 6 The present examples and comparative examples were carried out by extrusion molding.

The materials used are shown below.

Cement 15.0
3.3 4.55 Micro Silica 4.5 2.2 2.05 Mighty 150 0.3 1.0
0.3 valve 0.21 1.
4 0.15 silica sand #B 7.5 2
．． 2 3.41 total 32.28
14. Using an experimental omnimixer (manufactured by Chiyoda Giken Kogyo Co., Ltd.) with a quantitative determination of approximately 30%, first 7 minutes) 15
Kl, micro silica 4.5 Kq, water 4.5 Kg
, Mighty 150 0. Inject 3 Kq and 300 r
Kneaded at pm for 1 minute. Next, 0.21 kg of pulp was added and kneaded for 1 minute. Next, reinforcing fiber 0.27K
g was added and kneaded for 5 minutes, and finally silica sand #8 was added and kneaded for 2 minutes to obtain a mortar. Next, the mortar was extruded into an experimental extruder of the same type as a commonly used extruder.
! 1A (Miyazaki Iron Works Department), and was extruded into a plate shape (flat plate) with a thickness of 10 mm and a width of 316 rfa while being further kneaded, cut into lengths of 316 mm, and left indoors for 24 hours to harden. At this time, the volume fraction of the reinforcing film fibers to the volume of the molded product was 2%. The plates thus formed were naturally cured for 28 days and then subjected to physical property tests.

Table 2 shows the test results for the cement molded product.

In addition, Comparative Example 6 in Table 2 is a spun general PP fiber with a length of 9
CI+ was used.

Hehehehehe Table 2 Bending strength (K4/cj) 97.8 94.6
90.9 98.0 Impact strength (h・am/aj
) 13.9 12.5 12.1
12.6 Example 3 and Comparative Examples 7 to 9 This Example and Comparative Examples were carried out by the casting method.

The materials used are shown below.

Cement 15.0
3.3 4.54 Silica sand $6
9.0 2.2 4.09 Strong reinforced film fiber 15m) 0.27 0.91
0.3 water 6.0 1.0
6.0 Using an experimental omnimixer with a capacity of about 301, first add 15 Kp of cement, silica sand $6 to 9, and 6 Kg of f1 water to Mighty 1500.15.
Knead for 3 minutes and 30 seconds at 0 rpm. Next, reinforcing fiber 0,
27 kg was added and kneaded for another 1 minute and 30 seconds. Next, the mortar is 10 mm deep, 316 mm vertically, and 31 mm horizontally.
The mixture was poured into a 6 m frame, subjected to vibration molding using a vibrator (manufactured by Hayashi Vibrator) at approximately 3,000 vibrations per minute, and then left indoors for 24 hours to harden. At this time, the volume fraction of the reinforcing film fibers to the volume of the molded product is 2
%Met. Thereafter, it was removed from the mold frame, and the thus formed flat plate was naturally cured for 28 days, and then subjected to physical property tests.

Table 3 shows the test results for the cement molded product.

In addition, in Comparative Example 9, a spun general PP material having a length of 12 mm was used.

Table 3 Example Comparison Number of cases occurring (pieces/d) 7 27
0 43 Bending strength (K4/d) 81.5
78.8 73.0 76.5 Impact strength (K
f-cm/af) 12.7 11.5 1
0.8 9.6 [Effects of the Invention] As is clear from the data of the above-mentioned Examples and Comparative Examples, the cement molded product according to the present invention generates fewer fiber balls and is excellent in bending strength and impact strength.

Claims (1)

[Claims] 1. As the reinforcing fibers, chopped filament type polypropylene film fibers with a trunk and branch shape having a shape characteristic of average fineness of trunk fibers: 40 to 60 denier and aspect ratio of trunk fibers: 40 to 200 are used. 1. A cement molded article, characterized in that it is blended with a cement matrix of 0.3 to 5.0 volume % and molded. 2. The length of the main fiber of polypropylene film fiber is 3~
The cement molded article according to claim 1, which has a diameter of 18 mm. 3. The thickness of polypropylene film fiber is 25-35μ
A cement molded article according to claim 1. 4. Polypropylene film fibers are axially stretched, corona discharge treated and surfactant treated. Cutting strength: 50 kg/mm^2 or more Cutting elongation: 8% or less Elastic modulus: 1200 kg/mm^2 or more A cement molded article according to claim 1, 2 or 3 made from a polypropylene film having: 5. The cement molded product according to any one of claims 1 to 4, wherein the cement molded product has a thickness of 20 mm or less.