JPH0621371B2 - Foam yarn for rotating brush - Google Patents

Description

TECHNICAL FIELD The present invention relates to a foamed yarn used as a bristle material of a rotary brush of, for example, an automatic car washing machine, a window glass washing machine, or the like.

[Prior Art] Conventionally, as a bristle material of a rotating brush used in, for example, an automatic car washing machine, a non-foamed yarn having a branched cross section made of a non-foamed thermoplastic resin has been widely used. Some attempts have been made to use open-cell sponge rods and felt sheets as alternatives to this bristle material, but they have not been put to practical use.

Further, recently, as a substitute for a hair material, it has been proposed to use a flexible closed-cell foam sheet as it is or by slitting it into a rod shape (JP-A-61-271157 and JP-A-63-161904). ).

[Problems to be Solved by the Invention] However, the bristle material of the conventional rotary brush or a substitute thereof has the following problems.

(1) In the case of non-foamed yarn, the material is relatively hard,
There is a problem that the painted surface is easily scratched. In particular, with the recent increase in the gloss of the coated surface, the number of scratches on the coated surface is increasing, and scratches when rubbed with this brush poses a problem.

(2) In the case of the sponge rod-shaped body or felt sheet, the material is softer than the non-foamed yarn, and therefore the risk of scratching due to the hardness of the material is less than that of the non-foamed yarn.

However, the sponge or felt itself may absorb water, become heavy, and strongly hit the object to be cleaned, possibly damaging the object to be cleaned. In addition, sand or the like gets into the eyes of the sponge or felt during cleaning, and this easily hits the painted surface and scratches it, or stains clogging the eyes and shortening the service life. In addition, thick sponge rods and felt sheets make it difficult to scrub off dirt in the details, leaving a lot of unwashed residue.
If these are thinly slit, the strength is insufficient and a practical life cannot be obtained. Moreover, the waist is weak and it becomes a wrap around the rotating shaft, and it does not serve as a brush.

(3) The use of a closed-cell foam sheet is intended to solve the problem of water absorption by being a closed-cell foam while utilizing the benefit of the flexibility of the sponge or felt, and it is clearly high foaming. The foam sheet is used.

However, even if the problem due to the water absorption is solved by using the foam having closed cells, the highly foamed one cannot prevent the invasion of sand or dirt into the bubbles, and the problem due to this remains. Furthermore, if the foamed sheet is used as it is or if it is slit into a thick rod, there will be a large amount of unwashed residue, and if it is thinly slit, the strength and waist strength will be insufficient, and practical life and cleaning power cannot be obtained. That problem also remains.

The present invention has been made in view of the above conventional problems,
The problem of scratches on the coated surface of the rotating brush bristle is to be solved by improving the yarn used for the bristle rather than by using a bristle substitute that causes other problems such as foam sheets. To do.

[Means for Solving the Problems] The means taken in the present invention for solving the above problems will be described. In the present invention, the rigidity is 1200 kg / cm ^2.
Foamed yarn with a branched cross section made of thermoplastic resin of up to 5000 kg / cm ² and taking the means of making it as a rotary brushed foamed yarn having a foaming ratio of 1.1 to 1.7 times. Is.

The rigidity in the present invention means the Olsen rigidity measured by ASTM-A747. In addition, the expansion ratio is a value obtained by measuring the density of non-foamed yarn (non-foamed yarn) and the density of foamed yarn according to JIS-K7112 (underwater substitution method), and obtaining the ratio of foaming ratio = ρ ₀ / ρ _1. Say. Where ρ ₀ is the density of the non-foamed yarn and ρ
₁ is the density of the foamed yarn.

The present invention will be further described.

The foamed yarn of the present invention has a rigidity of 1200 kg / cm ^{2 to} 5000.
It must be composed of kg / cm ² of thermoplastic resin,
It is preferable that in particular is composed of 1300kg / cm ² ~4000kg / cm ² of thermoplastic resin.

The reason for this is to make the coated surface hard enough not to damage it, and to obtain the strength and strength of the waist required as the bristle material of the rotating brush. That is, it is preferable that it is soft from the viewpoint of protection of the coated surface, but it is necessary to have a waist strength that can scrub dirt during cleaning, and it is sufficiently resistant to pulling, friction, impact, bending, etc. applied during cleaning, and When the foamed yarn is entangled with the object to be cleaned, it is necessary to have strength enough to cut the object to be cleaned without damaging it. In addition, since the present foamed yarn has a branch-shaped cross section described later, it is easy to tear in shape, and tenacity that can prevent this tearing is required. Further, in order to satisfy such conditions, it is necessary to have a rigidity within the above range.

Further, the reason why the thermoplastic resin is used in the present invention is to enable continuous spinning by an extruder as in the case of the conventional non-foamed yarn.

As a specific thermoplastic resin that can be used in the present invention, polyolefin, copolymers or blends mainly composed of polyolefin and modified products thereof are preferable, and among these, polyethylene and blends mainly composed of these are suitable, In particular, low-pressure method linear low-density polyethylene and blends containing this as a main component are preferable.

Further, the thermoplastic resin used in the present invention has a density of 0.94.
Hereinafter, the melt index is preferably 0.3 to 4.0 g / 10 minutes, and particularly preferably 0.4 to 3.0 g / 10 minutes.

The foamed yarn has a branched cross-section, and this branched shape means that, as shown in FIG. 1, at least three branch trunks 1 are extended outward from the central portion. Refers to the shape.

This branched shape is similar to that of the conventional non-foamed yarn. By having such a cross-sectional shape, water easily adheres to the branch 1 due to surface tension, and the cleaning effect is improved by increasing the amount of water adhesion. Also, by making the cross-section into a branched shape, it is easy to obtain the required waist strength even with a relatively thin main foam yarn, and by adjusting the thickness of the branch trunk 1, a cushioning effect can be obtained and coating It is easy to protect the surface. In order to obtain this cushioning effect, the thickness of the branch trunk 1 is preferably 0.05 to 0.5 mm.

As the branched shape, in addition to the plus shape shown in FIG. 1,
It has a shape in which three branch trunks 1 project as shown in FIG. 2, a shape in which five branch trunks 1 project as in FIG. 3, and a shape in which six or more branch trunks 1 project. May be. Also, branch 1
4 has a triangular shape as shown in FIG. 4, a rounded tip as shown in FIG. 5, and further a branch trunk 1 as shown in FIGS. 6 and 7. It may have a branched shape, a spatula shape as shown in FIG. 8 or a protruding shape as shown in FIG.

The thickness of the foamed yarn is preferably 0.5 to 5 mm, particularly about 1 to 3 mm in diameter of the circumscribing circle shown by the one-dot chain line in FIG. If this diameter is too small, it will be difficult to obtain the required waist strength, and if it is too large, the impact on the item to be cleaned during cleaning will be large and it will be easily scratched, and the brush will become rough and leave unwashed residue. It tends to occur. Further, the protruding length of the branch trunk 1 is preferably 10% or more of this diameter.

Further, the thermoplastic resin constituting the foamed yarn is 1.1 to
It is necessary to foam in a range of 1.7 times, and it is particularly preferable to foam in a range of 1.15 to 1.5 times. If the expansion ratio is too low, the coated surface is likely to be damaged as with conventional non-foamed yarns. Conversely, if the expansion ratio is too high, the required waist strength and strength will not be obtained, and sand and dirt will adhere. Is likely to occur.

The present foamed yarn can be easily and continuously manufactured by extruding a thermoplastic resin to which a small amount of a foaming agent has been added, from a die having a shape similar to a desired cross-sectional shape. The draw ratio during this spinning is 3.0 to 6.0 times, particularly 4.0 to
It is preferably about 5.5 times. Further, its usage is similar to that of the conventional non-foamed yarn, and for example, it is arranged in multiple stages around the rotary shaft 2 as shown in FIG. 10 or spirally arranged as shown in FIG. Can be used.

[Operation] A particularly significant feature of the present invention is its expansion ratio, which prevents damage to the coated surface, which was conventionally considered to be flexible and highly elastically deformable as a high-foaming material, by using a non-foamed yarn and a waist. It has a great feature in that it has been found that it can be achieved with a low foaming ratio of 1.1 to 1.7 times, which does not significantly change the strength and strength.

The mechanism by which scratches on the painted surface are prevented under this low foaming condition is not always clear, but the present inventors presume as follows.

That is, in the case of low foaming, remarkable improvement in flexibility and elastic deformability cannot be obtained, but a certain amount of bubbles are formed, and the presence of the bubbles partially cavifies the foamed yarn on the coated surface. It is thought that the shock of time is greatly reduced.
Especially in the case of a rotating brush, cleaning is not performed with the brush's bristles always in contact with the object to be cleaned, but the bristles collide with the object to be cleaned as it rotates, and then the surface of the object to be cleaned is rubbed. Meanwhile, cleaning is performed by repeating the operation of separating from the object to be cleaned. It is considered that the coated surface of the object to be cleaned is damaged when the hair material hits the object to be cleaned, and the fact that the foamed yarn greatly reduces the impact at this time It is considered that it acts extremely effectively for protection.

By the way, according to an experiment by the present inventor, when the foamed yarn is used in an automatic car wash machine, the sound of the yarn hitting the vehicle body is changed to a considerably lighter sound as compared with the case where the conventional non-foamed yarn is used. It has been confirmed.

Further, if a high foam is used as in the prior art, it is not possible to form a thread from this in terms of strength, and it can only be used in the form of a sheet or slits. On the other hand, in the present invention, a low-foam material that does not significantly lower the strength and strength of the waist is used.
It can be used in the same form as a conventional non-foamed yarn.

[Example] Example 1 A low-pressure linear low-density polyethylene (rigidity: 3300 kg / cm ² ) having a density of 0.924 and a melt index of 0.8 was used as a foaming agent, and a die blow PE-MD20N (a foaming agent amount of 20) was used.
2.0% by weight masterbatch: Dainichi Seika Kogyo Co., Ltd.
% Was added and spinning was performed under the following conditions.

Extruder: Spinning machine for monofilament Screw diameter 40 mm L / D = 24 Compression ratio 3.0 Extruder setting temperature: C ₁ 170 ° C C ₂ 200 ° C H 200 ° C Die 190 ° C Spinner: Plus (+) shape Hole number 15 Spinning denier: 6000D / 1F Stretching ratio: 4.7 times When the expansion ratio of the obtained foamed yarn was measured, it was 1.2.
It was 6 times. The yarn was attached to an automatic car wash machine and a car wash test was conducted. As a result of observing the degree of scratches, scratches were scarcely seen and no unwashed residue was left, and good results were obtained.

Example 2 Spinning was performed in the same manner as in Example 1 except that the amount of the foaming agent added was 3.5%.

The expansion ratio of the obtained foamed yarn was 1.65.

As a result of carrying out a car wash test on this foamed yarn in the same manner as in Example 1, almost no scratch was observed, and this point was good. However, the waist strength of the foamed yarn is slightly lowered, the movement of the brush tends to be wavy, and the foamed yarn easily escapes to the protrusions of the vehicle body, which is not a problem in practical use. However, some of the details were left unwashed.

Example 3 Density 0.934, melt index 4.0, rigidity 4
Spinning was performed in the same manner as in Example 1 except that 600 kg / cm ² of low pressure linear low density polyethylene was used.

The expansion ratio of the obtained foamed yarn was 1.25.

As a result of carrying out a car wash test on this foamed yarn in the same manner as in Example 1, since the foamed yarn has a high rigidity, there is no problem in practical use, but scratches are slightly increased as compared with Example 1. Also,
Cracking of the foamed yarn was more likely to occur than in Example 1.

Comparative Example 1 Spinning was performed in the same manner as in Example 1 except that the foaming agent was not added.

A car wash test was conducted in the same manner as in Example 1 using the obtained non-foamed yarn, and as a result, the impact noise was considerably higher than that in Example 1,
Many scratches were observed. Especially when the glossy coated surface was viewed in the backlit state, the scratches were conspicuous, and it was clear that there was a problem in practical use.

Comparative Example 2 Spinning was performed in the same manner as in Example 1 except that the foaming agent additive was 1.0%.

The expansion ratio of the obtained expanded yarn was 1.04 times.

As a result of performing a car wash test using this foamed yarn in the same manner as in Example 1, the impact sound and the scratched state were not much different from those in Comparative Example 1, and the improvement effect by foaming was hardly recognized.

Comparative Example 3 Spinning was performed in the same manner as in Example 1 except that the amount of the foaming agent added was 4.0%.

The foamed yarn thus obtained had a foaming ratio of 1.82 times, and was a soft yarn having a considerably rough surface and a weak waist.

As a result of carrying out a car wash test using this foamed yarn in the same manner as in Example 1, first, the foamed yarn was likely to be wound around the rotating shaft, and the movement of the tip portion became wavy like a wave, and the tip of the foamed yarn was It is in a state where it does not hit the car body. In addition, the roots of the foamed yarns that have been planted may not be restored due to being partially broken even if used for a short period of time, which is not practical in terms of durability.

Comparative Example 4 Density 0.917, melt index 0.3, rigidity 1
Spinning was performed in the same manner as in Example 1 except that high-pressure low-density polyethylene of 100 kg / cm ² was used.

The expansion ratio of the obtained expanded yarn was 1.23 times. However, the draft property was inferior, yarn breakage was likely to occur, and spinning was difficult.

As a result of performing a car wash test using this foamed yarn in the same manner as in Example 1, not only the waist of the foamed yarn but also the tensile strength is insufficient, the tip is easily torn and worn, and it is not practical in terms of durability. There wasn't.

Comparative Example 5 Density 0.940, melt index 3.5, rigidity 6
Spinning was performed in the same manner as in Example 1 except that low-pressure linear low density polyethylene of 000 kg / cm ² was used.

The foaming ratio of the obtained foamed yarn was 1.25.

As a result of carrying out a car wash test using this foamed yarn in the same manner as in Example 1, it was clear that the rigidity was too high, the impact noise was high, and many scratches were generated, which was a problem in practical use.

[Effects of the Invention] The present invention is as described above and has the following effects.

(1) Since the impact when hitting the object to be cleaned is greatly reduced, the painted surface is hardly scratched.

(2) Since it has a thread shape similar to that of the conventional non-foamed thread, and the strength and strength of the waist are almost the same, it is easy to wash even a small portion without washing and has excellent durability.

(3) Since the foaming is low and a large number of bubbles are not exposed on the outer surface, it is difficult for sand and dirt to adhere, and it is possible to prevent damage to the painted surface and shorten the service life due to these adhesions. Further, for the same reason, not only does it absorb a large amount of water and becomes heavy and does not interfere with the cleaning, but also the cleaning effect is increased by the moderate roughness of the surface.

[Brief description of drawings]

1 to 9 are views showing examples of the cross-sectional shape of the present foamed yarn, and FIGS. 10 and 11 are views showing examples of use states of the present foamed yarn.

Claims (1)

[Claims] 1. A rigidity of 1200 kg / cm ^{2 to} 5000 kg / cm ²
A foamed yarn for a rotary brush, which is a foamed yarn having a branched cross-section made of the thermoplastic resin and having an expansion ratio of 1.1 to 1.7 times.