JP2946710B2 - Fiber assembly molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for molding a fiber assembly, and more particularly, to an automobile interior such as a dash insulator, a floor insulator, a roof liner, a food liner, a door trim, and a seat pad. The present invention relates to a molding method for producing a molded article having a complicated shape such as a material, a building material, a furniture pad, a bedding pad, and a clothing pad using a fiber as a material, and particularly to physical properties (bulk density) over the entire molded article. The present invention relates to a method for molding a fiber aggregate useful as a soundproofing material that requires homogeneity of the same, elastic modulus, ventilation resistance, and the like.

[Problems to be solved by conventional technology and invention]

Conventionally, a compression molding method, a blow molding method, and a combination method thereof have been used for the production of a molded body made of fiber.

That is, in the compression molding method shown in FIG. 2, fibers obtained by mixing a powdery or fibrous binder of a thermosetting resin or a thermoplastic resin are processed into a mat-shaped primary molded body a such as a nonwoven fabric or felt. After the primary molded body a is sandwiched between the molds 6 having the final product shape and subjected to heat compression molding, or an adhesive is applied to both surfaces of the primary molded body a, and then the both surfaces are covered with another material such as cloth. And compression molding to obtain a final molded body (fiber aggregate).

However, the portion p compressed during the compression molding has a higher density and harder than the other portions of the final molded body c, and it is impossible to obtain a shape larger than the thickness of the primary molded body a. . In addition, the entire final molded body c was soft and could not cope with a more complicated and deep-drawing shape, and the part p hardened by compression was not suitable for soundproofing performance.
If the density of the primary molded body a is reduced in order to cope with this problem, there is a problem that the transfer efficiency is reduced because the primary molded body a is very bulky, so that the distribution cost is increased.

On the other hand, in the blow molding method shown in FIG. 3, a mixture d of a binder and fibers is blown into a cavity f of a mold e by a blow fan g, and then the entire mold is heated and cooled to form a final molded body ( (Fiber aggregate) h. However, such a molding method requires more equipment and more time for one product, resulting in higher product cost, and the longer the fiber, the more difficult it is to blow into the mold. Therefore, there is a problem that the fiber length is limited.

The present invention has been made in order to solve the above-described problems, and can uniformly homogenize the physical properties of a fiber assembly having a complicated shape as a whole, without being limited by the fiber length.
It is an object of the present invention to provide a method for molding a fiber aggregate that can be efficiently formed in a desired shape in a short time and at low cost.

[Means and actions for solving the problem]

In order to achieve the above object, the present invention places a primary molded body of a fiber whose volume is increased by heating into a cavity of a mold, expands the fiber by heating the mold, and forms the primary molded body. When molding into the cavity shape, the fiber whose volume is increased by heating is a crimped fiber or a fiber using a foamable material, and the expansion of the fiber is a volume increase rate of the primary molded body. Is 50 ~
Provided is a method for molding a fiber aggregate, characterized in that the expansion is in the range of 800%.

According to the present invention, since the primary molded body of the fiber whose volume is increased by heating as described above is heated and expanded, a certain part is strongly compressed as in the conventional compression molding method and becomes high in hardness. Inconveniences are prevented as much as possible, and the hardness of the obtained fiber aggregate (final molded body) is almost the same over the whole, and there is little partial difference in physical properties. Therefore, even when the shape of the fiber aggregate is complicated, its overall physical properties are homogenized as much as possible, and a soft fiber aggregate can be easily molded, and the fiber length is not limited, A fiber aggregate having a desired shape and physical properties can be easily and reliably manufactured. Therefore, the fiber aggregate according to the present invention is suitably used as a sound absorbing material or the like.

Moreover, according to the present invention, it is only necessary to heat the primary molded body in the mold cavity, so that the production of the fiber aggregate can be efficiently performed in a short time, and the cost is advantageous.

 Hereinafter, the present invention will be described in more detail.

The method for molding a fiber aggregate according to the present invention uses a primary molded body of a fiber whose volume increases by heating.

Here, the kind of fiber used as the material may be any of inorganic fiber, organic fiber, natural fiber and synthetic fiber, but practically, polystyrene, polypropylene, polyester, polyamide, rayon, vinylon, acrylic, Polyurethane, acetate, cupra, cellulose, cotton, wool, hemp, and the like are used. These may be used alone or in combination of two or more. Fiber diameter,
There is no particular limitation on the length, but a length of 30 denier or less and a cut length of 10 to 100 mm is generally used.

The fibers need to be present in the primary molded body so that the fibers can expand or expand by heating to increase the volume. As a method for expanding or expanding the fiber by heating as described above, a method of using a fiber using a foamable material or the like can be adopted, but a method of crimping the fiber is particularly preferable. In this case, the number of crimps is appropriately selected.
More preferably, it is 10 peaks / inch or more. When two or more fibers are used, if at least one fiber is formed so as to be able to expand or expand by heating, other fibers are formed so as to be able to expand or expand by heating as described above. There is no problem even if it is not done.

In molding the primary molded body, it is preferable to use a binder in order to bind the fibers to each other. As such a binder, powder or fiber having a melting point lower than the melting point of the fiber material is preferably used. In general, thermoplastic polyethylene, polypropylene, polyester, polyamide,
Resins such as polyvinyl chloride, EVA (ethylene-vinyl acetic acid copolymer), polyurethane, and bituminous powders and fibers are used. Further, a thermosetting resin such as a phenol resin is also used. Further, as the binder, a composite fiber shape called a sheath-core type or a side-by-side type may be used. The binder may be used alone or in combination of two or more. The mixing ratio of these binders is usually 5 to 40% by weight of the fiber material, particularly preferably 5 to 20% by weight.

The method for producing the primary molded body is appropriately selected. For example, when crimped fibers and a binder are used, they are mixed well in advance, and the primary molded body is produced by a method known as a heat-sealing type nonwoven fabric producing method. Can be manufactured. Although the shape of the primary molded body is not particularly limited, a mat shape,
A plate shape or a spherical shape is preferable. The dimensions and apparent density of the primary molded body are determined in consideration of the degree of volume increase in the subsequent heating step. For example 5~30mm the thickness of the final molded article, when the apparent density and 0.01~0.20g / cm ^3, the thickness of the primary molded article 20mm or less, an apparent density of 0.08
It is adjusted to 0.30 g / cm ³ , but the dimensions and apparent density of the primary molded body are not particularly limited. The rate of increase in volume of the primary molded body due to heating is 50 to 800%, especially 100%.
~ 400% is preferred.

Next, in the present invention, the primary molded body is placed in a mold cavity, and the primary molded body is expanded by heating the mold. This will be described with reference to FIG. 1. In FIG. 1, reference numeral 1 denotes a mold composed of an upper mold 1a and a lower mold 1b, and a primary molded body 3 is put into a cavity 2 of the mold 1 (first mold 1). (FIG. A) Then, the mold 1 is heated to expand the primary molded body 3, and a fiber aggregate 4 having the same shape as the cavity 2 is molded.

Here, the heating of the primary molded body is preferably lower than the melting point of the fiber, and when a binder is used for bonding the fibers to each other, it is preferable that the heating be higher than the melting point of the binder.
When heating the mold, hot air can be passed through the cavity of the mold, or the inside of the cavity can be sucked, if necessary.

The fiber aggregate thus obtained is more uniform in physical properties as compared with those of the final molded article molded by the compression molding method, and can be processed in a shorter time than the blow molding method. Since a simpler molding device is sufficient, the product cost can be greatly reduced.

〔The invention's effect〕

According to the present invention, a fiber aggregate useful as a cushioning material having a complicated shape, a soundproofing agent, a heat insulating agent, and the like, has uniform physical properties as a whole, for example, in a state where there is no bias in soundproofing performance, and is reduced in a short time. It can be manufactured at low cost.

Hereinafter, the present invention will be described specifically with reference to Examples.
The present invention is not limited to the following examples.

Example 1 As shown in FIG. 1, 25 parts of polyethylene powder (melting point 130 ° C.) per 100 parts of polypropylene fibers (6 denier, cut length 51 mm) having a crimp number of 13.0 peaks / inch.
A plate-shaped (70 × 130 × 15 cm) primary molded body (apparent density 0.10 g / cm ³ ) consisting of components mixed with
Heated for 2 minutes at a temperature of ° C. When the molded body was taken out after cooling the inside of the mold to 100 ° C, the volume of the original plate-shaped primary molded body increased by about 120%, and the apparent density became 0.046.
A fiber aggregate (final molded body) having a three-dimensional shape of g / cm ³ was obtained. This fiber aggregate can be used as a dash insulator for a vehicle.

Example 2 As shown in FIG. 1, 10 parts of a low-melting polyester composite fiber (polyester core) was added to 100 parts of a polyester fiber (6 denier, cut length 38 mm) having a crimp number of 15.0 peaks / inch. With a low-melting polyester sheath structure, 4 denier, cut length 51 mm, crimp number 8 ridges / inch, sheath side melting point 95 ° C) and 15 parts polyethylene-polypropylene composite fiber (polypropylene sheath structure with polypropylene core) Primary molded body of 2D denier, cut length 51mm, crimp number 10 crests / inch, sheath side melting point 130 ° C) fully mixed at 110 ° C in plate form (60 × 120 × 1.0cm) Molded into. The apparent density was 0.166 g / cm ³ .

This primary molded body is set in a mold,
After heating for one minute, it was recooled to 80 ° C. The obtained fiber aggregate (final molded body) had a three-dimensional shape (80 × 150 × 2.5 cm) with an apparent density of about 0.040 g / cm ³ , increasing by about 315% in a sedimentary manner. This is also suitable for car dash insulators.

[Comparative Example 1] Compression molding method As shown in FIG. 2, 25 parts of a low-melting-point polyester composite fiber (100 parts of a polyester fiber (6 denier, cut length 38 mm) having a crimp number of 15.0 peaks / inch). Example 2
The same fiber as above) is mixed well, and at 110 ° C, 80 × 150 × 3.
The primary molded (apparent density 0.047 g / cm ³ ) was transferred to a mold, compression molded while heating again to 110 ° C, and the molded body was taken out. The density increased and hard parts were created.

Comparative Example 2 Blow Molding Method As shown in FIG. 3, a mixture of two kinds of fibers similar to that of Comparative Example 1 was blown into a mold by a blow fan, heated to 110 ° C., and then cooled again. The molded body was taken out. Although the quality of this molded article was excellent, it took 15 minutes to mold one.

[Brief description of the drawings]

FIG. 1 illustrates an example of the method of the present invention. A is a schematic sectional view of a mold before expansion of a primary molded body, B is a schematic sectional view of a mold after expansion of a primary molded body, and FIG. 2 illustrates a conventional compression molding method. A is a schematic sectional view of a mold before compression of a primary molded body, B is a schematic sectional view of a mold after compression of a primary molded body, and FIG. 3 is a view for explaining a conventional blow molding method. A is a mixture of a binder and a fiber. During blowing, B is a schematic sectional view of the mold after blowing the mixture. 1 ... mold, 2 ... cavity, 3 ... primary molded body, 4
…… Fiber aggregate.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) D04H 1/00-18/00

Claims (1)

(57) [Claims] 1. A primary molded body of a fiber whose volume is increased by heating is put into a cavity of a mold, and the fiber is expanded by heating the mold to mold the primary molded body into the cavity shape. At this time, the fiber whose volume is increased by the heating is a crimped fiber or a fiber using a foamable material, and the expansion of the fiber is such that the volume increase rate of the primary molded body is 50 to 800%. A method for molding a fiber aggregate, wherein the expansion is within a range.