JPH11957A - Three dimensionally molded sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continue fabricated effects after molding while molding fabrication can be executed at comparatively low temperature, and can be applied to fiber of any form by a method wherein three dimensionally molded sheet is composed of principal fiber consisting of organic or inorganic fiber, and a polyvinyl alcohol as a binder. SOLUTION: Three dimensionally molded sheet is composed of, for example, 50 to 97 wt.% of principal fiber consisting of organic or inorganic fiber, and, for example, 3 to 50 wt.% of polyvinyl alcohol(PVA) as a binder. Fly using the PVA component as the binder, the PVA component exists at an intersectional point of the principal fiber, two or more lines of principal fibers are tied per one intersectional point, and strength of the sheet is improved. Further, though the principal fiber is a component constituting a frame work of a nonwoven fabric structure, and all raw material corresponds thereto, it shall have a melting point or a softening point of not less than a glass transition temperature of the PVA component. Thereby, a very highly molding property is obtained by thermocompression bonding at a comparatively low temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensionally formed sheet such as a corrugated body, corrugated paper, or a honeycomb structure.

[0002]

2. Description of the Related Art Conventionally, in order to form a corrugated body such as a corrugated cardboard, corrugated paper, a honeycomb structure, and a three-dimensional forming sheet used for other materials, pulp or wool-like organic or inorganic fibers are mixed into the base paper. It was necessary to impart moldability. This aims at strengthening the physical entanglement of the fibers by heating and pressing in a state where the fibers are deformed into a shape to be processed, and aims at an effect of enhancing the formability.

[0003] In particular, when cellulose pulp is contained as a constituent component of a sheet, very high setting properties can be obtained by entanglement of fibers and hydrogen bonding. It has been used as many three-dimensional molding sheets. Also, in the case of wool fibers of organic or inorganic fibers, there has been a method of using the fact that they have moldability.

[0004] However, such a three-dimensional formability cannot be expected in a non-woven fabric or the like composed entirely of fibers having a chopped strand shape. Depending on the application and conditions of use, the non-woven fabric may have a configuration in which pulp and wool-like fibers are not mixed. In such a case, the moldability during three-dimensional molding due to fiber entanglement or hydrogen bonding is imparted. It was difficult.

[0005] Alternatively, as another method, the sheet can be three-dimensionally molded by heating and pressing at a temperature higher than the softening point or melting point of the fibers constituting the nonwoven fabric. In this case, it is very significant in that moldability can be obtained without mixing pulp or wool-like fiber.However, when the softening point or melting point is very high, such as inorganic fiber, heat-fusion is performed. It is not practical to provide moldability.

[0006]

Therefore, the following items can be considered as conditions required for a three-dimensionally molded sheet that can be easily molded.・ Mould be formed at relatively low temperature.
Applicable to any form of fiber. -Preferably, the processing effect after molding is maintained.

[0007]

Means for Solving the Problems The present inventors have found that a three-dimensional molding sheet using a polyvinyl alcohol component (hereinafter referred to as a PVA component) as a binder has very excellent three-dimensional moldability by thermocompression bonding at a relatively low temperature. In addition, the present inventors have found that a high-strength molded article can be obtained because of having a high effect as a binder.

[0008] That is, the present invention relates to a three-dimensional molding sheet comprising main fibers composed of organic or inorganic fibers and a polyvinyl alcohol component as a binder. The present invention also relates to a three-dimensional molding sheet comprising 50 to 97% by weight of main fibers made of organic or inorganic fibers and 3 to 50% by weight of polyvinyl alcohol component fibers. In the present specification, the main fiber,
The weight% of the PVA component is calculated by subtracting the weight of the three-dimensional molding sheet by 10%.
This is the ratio when 0 is set.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As the PVA component used as a binder in the present invention, there are polyvinyl alcohol (hereinafter referred to as PVA) fiber, PVA powder or liquid PVA. Further, the PVA component of the present invention includes a polymer compound obtained by partially saponifying polyvinyl acetate with an alkali, an acid, aqueous ammonia, or the like, and also includes a so-called poval. Although the degree of saponification of the above-mentioned poval is not limited, it is preferable that the PVA is composed of 40 to 100% by weight of partially saponified PVA and 0 to 60% by weight of polyvinyl acetate.

Further, the PVA component of the present invention includes PV
A derivatives are also included. For example, those having improved heat resistance by partially acetalizing PVA fiber, PVA powder or liquid PVA are also commercially available under the name of Vinylon, which also have good moldability, and are used in the PVA component of the present invention. included.

In practice, when PVA fiber or PVA powder is mixed with the main fiber, or when liquid PVA is impregnated or coated, the sheet is heated and dried once with moisture. By doing so, the PVA fibers are once dissolved in the hot water in the sheet during the heating process and then dried. As a result, the PVA component is spread to every corner of the surface of the main fiber. However, since the PVA component is particularly present at the intersections of the main fiber, the three-dimensional formability by thermocompression bonding is enhanced. Further, since the main fiber and the PVA component can be firmly bonded, a binder effect can also be exhibited.

The three-dimensionally formed sheet of the present invention is desirably composed of 50 to 97% by weight of main fibers made of organic or inorganic fibers and 3 to 50% by weight of a PVA component. P
If the content of the VA component is less than 3% by weight, sufficient moldability cannot be obtained and the effect as a binder cannot be expected sufficiently. Conversely, if the PVA component exceeds 50% by weight, the number of the main fibers is small, so that sufficient sheet strength cannot be obtained after hot press molding.

It is important that the three-dimensionally formed sheet of the present invention uses a PVA component as a binder, whereby the object of the present invention can be achieved. For example, when a hard resin such as an acrylic resin is used as a binder, a portion connecting the main fibers is too hard and lacks flexibility, and the setting property at the time of corrugation is poor. With a soft resin such as olefin, the elasticity of the resin itself is low, and the bonded portion is deformed by the repulsive force of the main fiber after setting, so that the corrugating property does not generally increase.

When a thermosetting resin such as a phenolic resin is used, it is difficult to control the degree of curing. If an uncured sheet is used, it is thermoplastic at a low temperature (around 80 ° C.). It sticks to stickiness and is poor in workability, and those with advanced curing degree have poor setability.

The "main fiber" in the present invention is a component constituting the skeleton of the nonwoven fabric structure.
All materials are applicable regardless of inorganic. However, if the melting point or softening point of the main fiber is 65 to 85 ° C., it becomes equal to or lower than the glass transition temperature of the PVA component. Therefore, the melting point or softening point of the main fiber must be equal to or higher than this temperature. No. Further, the shape of the main fiber used in the present invention corresponds to various types such as chopped strand, pulp, wool, whisker, and is not particularly limited.

The three-dimensional molded sheet of the present invention is formed into a three-dimensional molded product by thermocompression bonding using, for example, a corrugator. In the present invention, the temperature of thermocompression bonding is not particularly limited,
Since the glass transition temperature of the PVA component is about 65 ° C. to 85 ° C., if the thermocompression bonding is performed at a temperature higher than this temperature, three-dimensional moldability is exhibited for the sheet. However, in order to actually exhibit sufficient three-dimensional moldability, a temperature higher than this temperature of about 100
It is necessary to perform thermocompression bonding at a temperature of ℃ or more. On the other hand, if the temperature is too high, the shrinkage of the PVA component starts at 200 ° C.
Since the temperature reaches the softening point at ° C, when the temperature exceeds this temperature range, the combustion gradually starts while softening and shrinking. Therefore, the temperature of thermocompression bonding is preferably not too high.

[0017]

Next, the present invention will be described specifically with reference to the following examples.

Example 1 E-glass glass fiber chopped strand (produced by Unitika Ltd., fiber diameter φ6 μm, fiber length 6 mm) was used as a main fiber, and a slurry obtained by mixing 20% by weight of PVA fiber as a binder was used as an effective solid. It was prepared at a partial concentration of 0.1 wt%, and mixed with a wet method to obtain a wet nonwoven fabric. The obtained wet nonwoven fabric was dried at 145 ° C., and the fibers were bonded and fixed by dissolution of PVA fibers to form a sheet. This sheet was used as the three-dimensionally formed sheet of the present invention. Table 1 shows the characteristic values.

Next, the three-dimensionally formed sheet was corrugated at 180 ° C. by a corrugated cardboard processing machine, and the corrugated return rate after the processing was calculated. Corrugated return rate (%) = [(measured length after corrugate-theoretical length after corrugate) / (actual length before corrugate-theoretical length after corrugate)] x 100

Further, the three-dimensionally formed sheet was corrugated by changing the surface temperature of the step roll, and the corrugated return rate at that time was measured and summarized in FIG. 1 (corrugator pitch = 8.56 mm).

Example 2 E-glass glass fiber chopped strand (produced by Unitika Ltd., fiber diameter φ6 μm, fiber length 6 mm) 65% by weight
And a main fiber composed of 25% by weight of ceramic fiber (fiber diameter 2-3 μm), and a slurry containing 10% by weight of PVA fiber as a binder is prepared at an effective solid content of 0.1% by weight. The mixture was mixed to obtain a wet nonwoven fabric. The obtained wet nonwoven fabric was dried at 145 ° C., and the fibers were bonded and fixed by dissolution of PVA fibers to form a sheet. This sheet was used as the three-dimensionally formed sheet of the present invention. Further, using this sheet, corrugating was performed in the same manner as in Example 1, and the corrugated return rate was measured. Table 1 shows the characteristic values of the three-dimensionally formed sheet and the corrugated return rate after corrugating.

Comparative Example 1 E glass circular cross section glass fiber chopped strand (manufactured by NEC Corporation, fiber diameter φ9 μm, fiber length 13)
mm) 98% by weight as main fiber and PVA as binder
A slurry containing 2% by weight of fibers is mixed with an effective solid content of 0.1 wt.
% Prepared. Thereafter, a three-dimensionally formed sheet was prepared under exactly the same conditions as in Example 1, and further corrugated. The same items were measured. Table 1 shows the characteristic values of the three-dimensionally formed sheet and the corrugated return rate after corrugating.

Comparative Example 2 E glass circular cross section glass fiber chopped strand (manufactured by NEC Corporation, fiber diameter φ9 μm, fiber length 13)
mm) 90% by weight as the main fiber and a slurry obtained by mixing 10% by weight of heat-fusible core-sheath olefin binder fiber (Daiwa Spinning Co., Ltd., fiber diameter φ0.9 de, fiber length 5 mm) as a binder It was prepared with a concentration of 0.1 wt%. Thereafter, a three-dimensionally formed sheet was prepared under exactly the same conditions as in Example 1, and further corrugated. The same items were measured. Table 1 shows the characteristic values of the three-dimensionally formed sheet and the corrugated return rate after corrugating.

Comparative Example 3 E glass circular cross section glass fiber chopped strand (manufactured by NEC Corporation, fiber diameter φ9 μm, fiber length 13)
mm) 90% by weight as a main fiber, and the slurry was wet-processed at an effective solid content of 0.1% by weight to obtain a wet nonwoven fabric. 10% by weight of an emulsion of an acrylic resin was sprayed as a binder in the state of this wet nonwoven wet paper. After that, a sheet for three-dimensional molding was created under exactly the same conditions as in Example 1,
Furthermore, corrugated processing was performed. The same items were measured. Table 1 shows the characteristic values of the three-dimensionally formed sheet and the corrugated return rate after corrugating.

Comparative Example 4 E glass circular cross section glass fiber chopped strand (manufactured by NEC Corporation, fiber diameter φ9 μm, fiber length 13)
mm) A slurry containing 90% by weight of a main fiber and 10% by weight of a phenol resin powder as a binder was prepared at an effective solid content of 0.1% by weight. Thereafter, a three-dimensionally formed sheet was prepared under exactly the same conditions as in Example 1, and further corrugated. The same items were measured. Table 1 shows the characteristic values of the three-dimensionally formed sheet and the corrugated return rate after corrugating.

Comparative Example 5 E glass circular cross section glass fiber chopped strand (manufactured by NEC Corporation, fiber diameter φ9 μm, fiber length 13)
mm) 90% by weight and NBKP pulp (Crestbrook Forest Indu
A slurry containing 10% by weight of a main fiber composed of 10% by weight (freeness 250 ml, manufactured by stry) was prepared at an effective solid content of 0.1% by weight. Thereafter, a sheet for three-dimensional molding was prepared under exactly the same conditions as in Example 1 and further corrugated. The same items were measured. Table 1 shows the characteristic values of the three-dimensionally formed sheet and the corrugated return rate after corrugating.

[0027]

[Table 1]

[0028]

According to the three-dimensionally formed sheet of the present invention, the sheet strength itself can be improved by the effect as a PVA binder. The improvement in strength is due to the presence of the PVA component at the intersections of the main fibers, thereby securing two or more main fibers at one intersection. The strength is enhanced three-dimensionally, but when the strength of the main fiber itself is low, the maximum strength depends on this.

According to the present invention, it is possible to obtain a three-dimensionally formed sheet having extremely high formability by thermocompression bonding at a relatively low temperature.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the surface temperature of a step roll and a corrugated return rate in Example 1.

Claims (2)

[Claims] 1. A main fiber comprising an organic or inorganic fiber,
A three-dimensional molding sheet comprising a binder and a polyvinyl alcohol component. 2. A main fiber 50 comprising an organic or inorganic fiber.
To 97% by weight, and polyvinyl alcohol component fibers 3 to 5
The three-dimensionally formed sheet according to claim 1, comprising 0% by weight.