JP3137793B2 - Method for producing moldable fiber base material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a moldable fiber substrate,
In particular, the present invention relates to a method for producing a moldable fiber base material useful as an interior material for an automobile ceiling material, a door trim, a rear shell, a floor mat, a trunk circumference, a console, and the like, and also as a molding material for a package tray, a hat, a wall material, and the like.

[0002]

2. Description of the Related Art Conventionally, the above-mentioned interior materials for automobiles include:
Needle punch carpets having the following moldability have been frequently used.

(I) A fiber mat made of polyethylene terephthalate fiber, wool or the like, and polyethylene (melting point 118
C), linear polyester (melting point 140 ° C), polypropylene (melting point 135-164 ° C) and other low-melting fiber mats. Needle punched carpet in which fibers are melted and fibers are bonded.

(Ii) A needle punch carpet obtained by impregnating a fiber mat obtained by needling with an aqueous emulsion of a thermoplastic resin and then drying.

[0005] However, the carpet (i) generally has excellent cushioning properties and light weight, but has insufficient moldability and rigidity. In addition, the carpet (ii) has good cushioning properties, but it is difficult to achieve both heat retention and rigidity, and if the rigidity is increased, the amount of the fiber mat and the amount of the resin aqueous emulsion increase. Therefore, there is a problem that lightness is impaired.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to various interior materials for automobiles, which are excellent in rigidity and cushioning property in a well-balanced manner, have good moldability and heat-resistant mold retention properties, and are excellent in lightness. It is intended to provide a method for producing a suitable fiber base material.

[0007]

According to the present invention, there is provided a process for producing a moldable fibrous base material comprising the steps of: preparing a fiber (A) 1 having a melting point of 100 to 200 ° C.
A mat of mixed fibers consisting of 5 to 50% by weight and 85 to 50% by weight of a fiber (B) having a melting point of at least 40 ° C. higher than the fiber (A), and continuously in the thickness direction of the mat. Alternatively, mixing the fiber (B) with a carpet needling a mixed fiber mat in which the mixing ratio of the fiber (A) and the fiber (B) is changed so that the mixing ratio of one of the fibers gradually increases. After applying a resin aqueous emulsion having a film forming temperature of 40 ° C. or less from the side having a higher ratio, the fiber (A) is heated to a temperature at which the fiber (A) melts but the fiber (B) does not melt, thereby melting the fiber (A). This is a method characterized in that pressure and compression are performed in a state of being compressed.

The needled carpet according to the present invention has a fiber (A) having a melting point of 100 to 200 ° C.
A mixed fiber mat consisting of 85% to 50% by weight of a fiber (B) having a melting point of at least 40 ° C. higher than that of the fiber (A), and continuously or stepwise in the thickness direction of the mat. And a needling of a mixed fiber mat in which the mixing ratio of the fiber (A) and the fiber (B) is changed so that the mixing ratio of the fiber is increased.

The fiber (A) preferably has a fiber thickness of 1.2 to 300 denier and a fiber length of 25 to 150.
mm. The fiber (B) preferably has a fiber thickness of 1.2 to 300 denier and a fiber length of 25 to 1.
50 mm.

If the melting point of the fiber (A) is too low, the carpet shrinks when the applied aqueous emulsion is heated and dried, and if the melting point is too high, the difference in melting point from the fiber (B) is caused. And the fidelity of the mold at the time of pressurization and compression is reduced.
Are used. Preferred fibers (A) include polyethylene (melting point 118 ° C.), linear polyester (melting point 140 ° C.), and polypropylene (melting point 135-16).
4 ° C.).

The fiber (B) is four times more than the fiber (A).
Fibers having a melting point higher than 0 ° C., preferably higher than 70 ° C. are used. If the melting point of the fiber (B) is too close to the melting point of the fiber (A), the fiber (B) undergoes heat shrinkage during pressurization and compression, and the appearance and design as a carpet deteriorate significantly. Specific examples of the fiber (B) used include synthetic fibers such as polyethylene terephthalate and polyamide;
Natural fibers such as cotton, hemp, and wool can be used.

The mixing ratio of the mixed fiber in the needling carpet of the present invention is such that the fiber (A) is 15 to 50% by weight, preferably 20 to 40% by weight, and the fiber (B) is 85% by weight based on the total amount of the mixed fiber. ５０50% by weight, preferably 80-60% by weight. If the proportion of the fiber (A) is too small, in other words, if the proportion of the fiber (B) is too large, the rigidity and heat-resistant shape retention of the obtained fiber base material become insufficient,
Conversely, if the proportion of the fiber (A) is too large, the texture of the fiber base material is impaired, and the cushioning property is reduced.

In the needling carpet of the present invention, the mixing ratio of the fibers (A) and (B) is changed so that the mixing ratio of one of the fibers increases continuously or stepwise in the thickness direction of the mat. Although it is a carpet needling a mixed fiber mat, in order to manufacture a mixed fiber mat in which the mixing ratio of the fibers is changed, for example, the fibers (A) and (B) are sufficiently mixed and opened at a specific ratio. The mixed fiber mat obtained by a method of repeating the operation of supplying a mixed fiber having a higher mixing ratio of one of the fibers to the web forming apparatus and stacking the mixed fiber, on the stacked material supplied to the web forming apparatus, There is a method of needling in the vertical direction and interlocking the fibers to temporarily fix them.

As another production method, the fiber (A)
For example, a fiber (A) is placed on a carpet needled with a mixed fiber mat having a specific mixing ratio of a fiber (A) and a fiber (B).
There is also a method in which a mixed fiber mat with an even higher mixing ratio is stacked and needling, and this operation is repeated.

An aqueous resin emulsion having a film forming temperature of 40 ° C. or less is applied to the needling carpet thus obtained from the side where the mixing ratio of the fiber (B) is high. This aqueous resin emulsion has the effect of increasing the adhesiveness between fibers, and at the same time, by adding a colorant, particularly a pigment colorant, to the aqueous resin emulsion, enhances the design of the obtained fiber base material. A color tone that is preferable as an interior material can be obtained. As the pigment colorant, those which are used for coloring ordinary aqueous resin emulsions may be used. In addition, the resin aqueous emulsion,
If necessary, a pigment dispersant, an extender for increasing the color of the fiber itself, and the like can be added.

The aqueous resin emulsion has a film forming temperature of 40
An aqueous resin emulsion at a temperature of at most 20 ° C., preferably at most 20 ° C., is used, because if the film-forming temperature of the resin is too high, the texture of the fiber base material obtained is impaired and the cushioning properties are reduced. Even when the film forming temperature of the resin aqueous emulsion is 40 ° C. or higher, the film forming temperature can be controlled to 40 ° C. or lower by adding a film forming auxiliary such as texanol, benzyl alcohol, and butyl cellosolve. However, in this case, the heating of the carpet in the subsequent process, or when forming, the film-forming aid may transfer to the surface, it is desirable not to add too much film-forming aid .

Aqueous resin emulsions are prepared by using monomers such as styrene, alkyl acrylates, alkyl methacrylates, ethylene, vinyl chloride, vinyl acetate, vinylidene chloride, and diene compounds alone or in various combinations. By emulsion polymerization in an aqueous medium according to the above method. In particular, the resin for the aqueous resin emulsion is easy to design an emulsion having a film forming temperature of 40 ° C. or lower, and therefore, a styrene-alkyl acrylate copolymer, a methacrylic alkyl ester-alkyl acrylate copolymer,
A styrene-diene compound copolymer is desirable.

The aqueous resin emulsion is applied to the needle punch carpet from the side where the mixing ratio of the fiber (B) is high. This is to fix the fiber (B), and a colorant is added to the aqueous resin emulsion. In the case where it is present, the purpose is to enhance the appearance and design on the side where the mixing ratio of the fiber (B) as the surface layer is high.

The amount of the resin aqueous emulsion to be applied varies depending on the thickness of the needle punch carpet.
The resin content is 40 to 300 g / m ² , preferably 60 to ² g / m ² .
00 g / m ² . The application method is generally a roll method, a doctor knife method, or a spray method. In order to promote impregnation into a carpet, the carpet may be squeezed simultaneously with or after application through a press roll.

The needling carpet thus coated and impregnated with the aqueous resin emulsion is then heated to a temperature at which the fiber (A) melts but the fiber (B) does not melt to melt the fiber (A). Before the heating step, it is preferable to dry the applied impregnated needling carpet to some extent. By the drying, the physical properties, particularly hardness, of the obtained fiber base material can be improved, and this effect is remarkably exhibited when a resin aqueous emulsion having a high film forming temperature is applied.

The fiber (A) melts, but the fiber (B)
Are not melted, for example, at 130 to 250
° C, preferably 150 to 220 ° C. When the fiber (A) is melted by heating to a temperature at which the fiber (A) melts but the fiber (B) does not melt, the fiber (A) is melted and pressurized and compressed. The part functions as an adhesive, and a fiber base material in a state in which the fiber (B) and the fiber (A) are partially bonded to each other and entangled is obtained. Regarding the degree of pressurization / compression, if the compression ratio is too high (that is, if the apparent density of the produced fiber base material is too high), the cushioning properties of the fiber base material will be deteriorated and the rigidity will be too high. Conversely, if the compression ratio is too low (that is, if the apparent density of the formed fiber base material is too low), the rigidity becomes insufficient, so that the apparent density of the formed fiber base material is usually 0.15. It is desirable to compress to about 0.45 g / cm ³ .

In the present invention, as described above, the mixing ratio is changed so that the mixing ratio of one fiber is increased continuously or stepwise in the thickness direction of the mixed fiber mat.
In addition, the aqueous resin emulsion is applied from the side of the needling mat where the fiber (B) mixture ratio is high. By using such a method, rigidity and cushioning property are well-balanced, and heat-resistant mold retention property is kept good. be able to.

When the method of the present invention is changed to a method in which the aqueous resin emulsion is applied only from one side of the mat without changing the mixing ratio of the fibers, both the rigidity and the cushioning property are insufficient. It will be. Further, when the method of the present invention is changed to a method of applying the aqueous resin emulsion from both sides of the mat without changing the mixing ratio of the fibers, the cushioning property is reduced, and the weight of the fiber base material is increased. The effect cannot be improved in proportion to the operation.

Further, when the method of the present invention is changed to a method in which the aqueous resin emulsion is applied from the side where the mixing ratio of the fiber (A) is high, the fiber base material obtained is inferior in bending strength and cushioning property. (See Example 1 and Comparative Example 5).

[0025]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. “%” And “parts” described in these examples are all based on weight.

Example 1 A polypropylene fiber having a thickness of 15 denier and a fiber length of about 100 mm (melting point: 164 ° C.) (sometimes abbreviated as “PP”) 50%, a thickness of 15 denier and a fiber length of 75 to 1
25 mm polyethylene terephthalate fiber (melting point 26
4 ° C.) (sometimes abbreviated as “PET”) 50% of mixed fibers (180 g / m ² ) are stacked, and a mixture of 30% of the same polypropylene fibers and 70% of the same polyethylene terephthalate fibers (180 g / m ² ). ² ) Stack up,
On top of that, a mixed fiber (180 g / 180%) of 15% of the same polypropylene fiber and 85% of the same polyethylene terephthalate fiber was used.
m ² ), and a fiber mat (180 g / m ² ) made of only the same polyethylene terephthalate fiber is further stacked on the fiber mat (7 g in total of the fiber mat).
20 g / m ² ) using a needle of 15-18-32-3 RB with a needle of 50-18 per square inch (645 square mm).
Needling was performed at the ratio of books to obtain a needling carpet having a wall thickness of about 7.0 mm and an apparent density of 0.10 g / cm ³ .

Separately, an aqueous emulsion of a copolymer resin of styrene (30%)-butyl acrylate (68%)-acrylic acid (2%) — the film forming temperature of the emulsion is 0 ° C. or less, and the glass transition temperature of the resin ( Tg) was −18 ° C., and the solid content was 50%｝ (hereinafter referred to as “resin aqueous emulsion I”), and a pigment or the like was blended in the following ratio to prepare a gray colored resin aqueous emulsion.

Resin aqueous emulsion I 100 parts Water 80 parts Titanium oxide 40 parts Calcium carbonate 20 parts Thickener * 1 50 parts Coloring material * 2 5 parts * 1: 2% aqueous solution of hydroxyethyl cellulose * 2: Large Nippon Seika Co., Ltd. Product name EP-510 Black

The above-obtained needling carpet was roll-coated with the above-mentioned aqueous resin emulsion colored in gray from the side having a high polyethylene terephthalate content so that the resin content was 200 g / m ² . The resin emulsion was impregnated into the carpet through a nip roll.

Next, the needling carpet to which the resin emulsion has been applied and impregnated is dried using a cylinder drier (internal temperature of 150 ° C.) to remove water, and then the dried carpet is subjected to a suction drier (internal temperature of 190 ° C.). ° C) for 3 minutes to melt the polypropylene fiber, and compress the carpet with the polypropylene fiber in a molten state through a cooling roll to obtain a basis weight of 920 g.
/ M ² , and a fiber base material having a wall thickness of 4.1 mm.

Table 1 shows the production conditions of the fiber base material and the results of the following evaluation tests on the obtained fiber base material.

Flexural strength A sample of 15 cm × 5 cm was taken from the fiber base material, and 5 cm at the center of the span of 10 cm using an Instron type testing machine.
/ Min, and measured the three-point bending strength (maximum bending strength at 5 cm width).

Cushioning A 4 cm × 4 cm sample piece is taken, placed on a table, and a 1 cm × 1 cm pressure terminal is applied to the center of the sample piece with a pressure of 0.2 kg / cm ² using an Instron type testing machine. After loading,
When the pressure was released, the one in which the pressure terminal returned upward was evaluated as having cushioning properties.

After shaping the base material, the fiber base material is heated with hot air of 190 ° C. for 3 minutes, and then heated to 0.35K.
g / cm ² G, with the colored surface facing up, compression molding to form a tray-shaped molded product having a length of 20 cm and a width of 20 cm and a depth of 3 cm. The salmon was examined and evaluated according to the following criteria. ○ ・ ・ ・ Thin with no base ×× Thin with base

[0035] The tray-like molded product obtained in the above section was left in an oven at 95 ° C for 1 day, and the degree of deformation after removal was visually judged, and evaluated according to the following criteria. ○ ・ ・ ・ No deformation is recognized △ △ Slight deformation × ・ ・ ・ Deformed to the extent that the original shape is not retained

Comparative Examples 1 to 5 The conditions for producing the fiber base material were changed as shown in Tables 1 and 2, respectively. Other than that, various fiber base materials were manufactured according to the method of Example 1. The same test as in Example 1 was performed on each of the obtained fiber base materials, and the results are as shown in Tables 1 and 2.

[0037]

[Table 1]

[0038]

[Table 2]

Notes in Table 2: * 1 ... Continuous means that each time a fiber mixed layer having a different structure is stacked, it is needled to entangle the fibers, and the composition of the fibers is substantially in the thickness direction. It means to change continuously. * 2 ... In Comparative Example 5, the application of the aqueous resin emulsion was performed.
A fiber base material was manufactured in the same manner as in Example 1, except that the needling carpet was changed so as to be applied from the side where the mixing ratio of the polypropylene fiber was high.

As can be seen from Tables 1 and 2, Example 1
Compared with the fiber substrate of the comparative example, the fiber substrate has excellent rigidity (bending strength), cushioning property, and heat resistance (heat-resistant mold retention) of the molded product in a well-balanced manner.

[0041]

The fiber substrate obtained by this method has a good balance of cushioning properties, moldability, and heat resistance (heat-resistant mold retention properties), and is also excellent in light weight. Suitable for interior materials of automobiles.

Continuing from the front page Examiner Hiroaki Hirai (56) References JP-A-62-299582 (JP, A) JP-A-56-43457 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) D04H 1/00-18/00 D06M 13/00-15/72

Claims (2)

(57) [Claims] 1. A fiber (A) 15 having a melting point of 100 to 200 ° C.
And a fiber (B) having a melting point of at least 40 ° C. higher than the fiber (A) by a plurality of layers of a mixed fiber consisting of 85 to 50% by weight, and a thickness direction of the mat. And a plurality of layers of mixed fibers in which the mixing ratio of the fiber (A) and the fiber (B) is changed so that the mixing ratio of one of the fibers increases sequentially or stepwise. A resin aqueous emulsion having a film formation temperature of 40 ° C. or less is applied to the carpet needling a mat from the side where the mixing ratio of the fiber (B) is higher, and then the fiber (A) is applied.
Wherein the fiber (A) is heated to a temperature at which the fiber (A) melts but the fiber (B) does not melt, and the fiber (A) is pressed and compressed in a molten state. 2. The method according to claim 1, wherein the aqueous resin emulsion is an aqueous emulsion colored with a pigment.