JPH10252000A - Prefilter raw paper for car air conditioning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain prefilter raw paper for car air conditioning excellent in folding suitability and strength keeping property by subjecting glass fiber, a synthetic fiber and a binder fiber to wet blending and impregnating a synthetic resin thereto. SOLUTION: Mixed slurry containing 30-70 pts.wt. glass fiber having 6-13×m fiber diameter, 30-70 pts.wt. synthetic fiber having 5-25μm fiber diameter, 1-10 pts.wt. binder fiber and an adhesive is formed into a sheet by a wet papermaking method. Then, a synthetic resin such as acrylic emulsion is impregnated into the sheet to provide the objective raw paper for crude layer part filter on air inlet side in an outside air-introducing type filter material for automobiles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter medium for use in an outside air introduction type air-conditioning filter of an automobile, which has a multilayer structure and is located on the outside air introduction side (inflow side). More specifically, of the filter material for the outside air introduction type filter of the vehicle, which has a density gradient from the coarse layer portion on the air inflow side to the dense layer portion on the air outflow side, and is composed of at least two or more fiber layers, It relates to a rough layer portion.
In the present invention, the prefilter refers to a coarse layer portion which is a fiber layer having a large fiber diameter in a filter medium for a filter having a multilayer structure in which a density gradient is provided from coarse to dense in a flow direction of air.

[0002]

2. Description of the Related Art Conventionally, an outside air introduction type car air conditioner directly cools outside air without a filter, so that exhaust gas from a diesel vehicle, pollen, and the like are also contained in the vehicle. On the other hand, European cars have been equipped with a dust filter at the entrance to the outside air and have been regularly replaced, and some Japanese cars have car air conditioners as standard. In most cases, such a filter for a car air conditioner is a combination of a synthetic pre-filter made of synthetic fibers and a main filter made of synthetic fibers and attached in a wave shape. However, since these co-synthetic filters are foldable and thermocompression-bonded, they are not rigid and have low operating efficiency in multi-layer bonding. There is a problem that the effective area may be significantly reduced.

[0003] Regarding these problems, air filters have heretofore been known to be mixed with thick glass fibers in order to maintain mechanical strength. However, simply mixing thick fibers causes voids in the fiber layer. Not only did the airflow resistance decrease due to the increase in the rate, but in particular, in the case of mainly glass fiber, streaks were cut off during folding, which further developed another problem such as falling off of the broken glass fiber.
In addition, when the glass fiber is a constituent fiber of a dense layer portion that is important in passing accuracy and passing efficiency, there is an inevitable disadvantage that the thickness of the entire filter becomes unnecessarily large, or that the efficiency of the filter is reduced. . In particular, this can be a fatal drawback in a vehicle where installation space is limited.

On the other hand, instead of mixing glass fibers,
A method of attaching a resin adhesive to a synthetic fiber layer is also known. This is a method in which a sheet is given a certain degree of hardness by using and impregnating a resin adhesive. For example, JP-A-6-218210 proposes a binder having a high glass transition temperature in order to harden a filter material. However, in the resin impregnation method, migration of the resin occurs due to evaporation of water during drying after the impregnation, so that a large amount of resin adheres to the surface of the sheet, and the porosity of the surface of the sheet significantly increases. And the filtration life is reduced.

Various methods have been devised for the migration of the sheet surface portion.
2-253815 proposes to minimize the occurrence of migration by using an organic solvent having a high evaporation speed during sheet drying as a dispersant or a solvent. However, even in this case, the occurrence of migration on the sheet surface is not completely suppressed. Further, since the filter base material is made more rigid than the resin adhesive, reducing the amount of the resin adhesive to suppress the occurrence of migration does not achieve the initial purpose of maintaining rigidity.

[0006]

SUMMARY OF THE INVENTION The present invention has a certain degree of rigidity, and provides a main filter (dense layer portion) of a combined synthetic fiber layer with foldability and strength maintenance. An object of the present invention is to provide a pre-filter base paper for a car air conditioner, which is free from generation and has excellent operation efficiency at the time of multi-layer lamination. In the present specification, a coarse layer portion, which is a fiber layer having a large fiber diameter in a filter material for a filter having a multilayer structure in which a density gradient is given from coarse to dense in the flow direction of air, is referred to as a prefilter, and a fiber diameter The dense layer, which is a thin fiber layer, is defined as a main filter.

[0007]

SUMMARY OF THE INVENTION The present invention has a density gradient from a coarse layer on the air inflow side to a dense layer on the air outflow side.
The present invention relates to a rough layer portion on the air inflow side of a filter medium for an outside air introduction type filter of an automobile having at least two or more fiber layers. In the present invention, the composition of the coarse layer portion is such that the glass fibers having a fiber diameter of 6 to 13 μm are 30 to 70 parts of the total weight of the substrate, and the fiber diameter is 5 to 25.
30 to 70 parts of synthetic fiber of μm, 1 to 10 of binder fiber
And 0.1 to 15 parts by weight of synthetic resin layer, "and is an invention of a pre-filter base paper for a car air conditioner, characterized in that the main filter of the combined synthetic fiber layer has foldability and strength maintenance.

The second invention of the present invention is the base paper for a pre-filter for a car air conditioner according to the first invention, wherein the base material is produced by a wet papermaking method. Hereinafter, the present invention will be described.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The pre-filter for a car air conditioner according to the present invention is obtained by heat-sealing glass fiber, synthetic fiber, binder fiber and synthetic resin. The present invention also aims to provide a role as a support for a main filter of a dense layer portion which is a synthetic fiber layer, and has a drawback that a conventional filter for a car air conditioner including a synthetic fiber layer has no rigidity. For improvement, attention has been paid to the fiber configuration that is considered to be the main cause, and the rigidity of the filter material combined in multiple layers has been increased by including large-diameter glass fibers in the configuration of the fiber layer of the pre-filter portion. Furthermore, by mixing glass fiber, the amount of synthetic resin used to make the base material combined in multiple layers rigid is reduced,
We succeeded in suppressing the deterioration of filter characteristics due to binder migration. The examples of the present invention are obtained by a wet papermaking method. In the wet papermaking method, since the base material has a very uniform structure by proper selection of the fibers used, stable rigidity can be obtained, and it is extremely effective as a support for the base material.

[0010] The coarse layer on the air inflow side in the filter of the multilayer combination is an important fiber layer that determines the filtration life of large-diameter dust. It is preferable that the dusts pass through. Therefore, in the case of a pre-filter, the contribution to dust collection as an air filter is small, and a large porosity is required.
Therefore, from the viewpoint of airflow resistance, the fiber diameter of the coarse layer portion of the multilayer combination is usually 5 to 25 μm, which is a relatively large diameter.
And a suitable result is obtained. Further, the glass fiber mixed in the coarse layer portion is for maintaining the rigidity of the filter substrate, but for the same reason, the average fiber diameter is preferably 6 to 13 μm. In the case of a glass fiber, if the average fiber diameter exceeds 20 μm, the foldability is reduced and a problem such as breakage of a stripe occurs.

In the present specification, the term "glass fiber" is used to mean long and short fiber glass fibers known as "glass chopped strands", and the composition of the fibers is not particularly limited. Absent. Here, in order to obtain rigidity as a filter support, the glass fibers used in the present invention have an average fiber diameter of 6 to 13
μm, preferably about 10 μm is suitable.

By combining a base material containing glass fibers in a fiber layer with a synthetic fiber layer, the filter base material can have a certain degree of hardness, and the prefilter can be a support in the filter base material. . In this case, although the rigidity can be obtained as the proportion of the glass fiber increases, if the proportion of the glass fiber is too large, streak breakage may occur during folding. Therefore, the ratio of the glass fiber occupies 30 to 70 parts, preferably 40 to 60 parts, while maintaining the hardness required for the filter substrate, it is possible to suppress the streak breakage during folding processing, filter Good results are obtained for the important foldability which influences the quality in production.

The synthetic fibers used in the present invention include organic fibers such as rayon, polyester, polyamide, and polypropylene, and the type of the fibers is not particularly limited. These may be used alone or in combination of two or more.

The synthetic fiber has an average fiber diameter of 5
2525 μm. If the thickness exceeds 25 μm, it is difficult to obtain a uniform fiber distribution, and even if a uniform fiber distribution is obtained, the fiber gap becomes too large. It causes problems. If the diameter is less than 5 μm, the voids of the fiber layer become extremely small, so that the filtration resistance increases, and not only large-sized dust but also small-sized dust is retained. Not preferred. Furthermore, premature clogging has the disadvantage of shortening the filtration life, and cannot fulfill the intended purpose of the prefilter. In the present invention, those having a thickness in the above range may be appropriately selected, but more preferably those in which the fibers having an average fiber diameter of about 10 to 20 μm occupy 30 to 70 parts of the filter substrate are dusts having a large particle diameter. It works well for pre-filters and gives good results.

In the present specification, the term "binder fiber" means that the appearance is not different from that of a general chemical fiber, but the binder effect is exhibited by heating at 100 to 200 ° C. after mixing with the fiber. Is used to mean that fibers can be bound together. Since glass fibers do not contribute to the strength, the strength of the sheet is increased by mixing the binder fibers to provide a prefilter with low pressure loss. The binder fiber used in the present invention,
Vinylon (VPB 107-1 manufactured by Kuraray Co., Ltd.) is not particularly limited, and thermosetting resins such as epoxy resin, acrylic resin, polyester resin, and polyolefin resin;
Any of thermoplastic resins can be used. However, from the viewpoint of the filtration resistance as the prefilter, a preferable fiber diameter of the binder fiber is about 5 to 25 μm. The binder is 0.5 to 15 based on the total nonwoven fabric weight.
Parts, preferably 2 to 6 parts.

In the present invention, by impregnating a suitably selected amount of the resin adhesive, the rigidity can be finely adjusted, so that a finer rigidity requirement can be satisfied for the base material.
That is, it is possible to provide the rigidity required for the base material-appropriate folding workability in accordance with the intended filter base material. As a method for impregnating the sheet with the resin adhesive, a method such as an immersion method or a spray method is used. The sheet of the present invention is impregnated with an acrylic copolymer (Yodosol 3460 manufactured by Kanebo NS). However, as the resin to be impregnated, the type of synthetic resin, such as an ethylene vinyl acetate copolymer or an ethylene vinyl chloride copolymer, is not particularly limited as long as it does not form a large film of an emulsion type and has an appropriate strength. Not something. If the amount of the impregnated resin is too large, migration of the surface of the base material occurs, so it is important to find an appropriate amount. In the present invention, the weight ratio of the base material and the impregnated resin is 0.1 to part, preferably 1 to 10 parts by weight of the impregnated resin relative to the total weight.

[0017]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the content of the present invention is not limited to Examples. In this embodiment, a pressure loss (mmAq) at a wind speed of 40 cm / sec is measured as an index of filtration resistance. The lower the value of the pressure loss, the lower the filtration resistance.
In the present embodiment, a hot bending holding angle is measured as an index of hot folding workability. The term “thermal bending holding angle” used in this specification refers to the return of the substrate when the folded sheet with a load of 30 g / cm2 applied to the upper part of the sheet is left in an atmosphere of 70 ° C for 20 minutes, and then loses the load. The angle is measured, meaning the heat setting property, and the more rigid, the larger the holding angle.

<Examples 1 to 7> A slurry of glass fiber and synthetic fiber was mixed so as to have a fiber structure shown in Table 1 below. To this mixture, polyethylene oxide (PEO) was added as a thickening agent to a concentration of 5 ppm, and the mixture was sheeted to 50 g / m2 using a sloping short screen machine. The sheet was impregnated with a synthetic resin (acrylic emulsion) to form a rough layer. As a part, a prefilter as shown in Table 1 was obtained. The pressure loss and the heat bending retention angle of the obtained prefilter at a wind speed of 40 cm / sec were measured, and were used as indices of filtration resistance and hot folding workability, respectively. In the heat folding setting property, the sample size is 5 * 10 cm, that is, 5 * 5 cm when folded in two. The holding angle increases as the stiffness increases, but the optimal value as the hot-foldability is 130 to 150 °.
Furthermore, the evaluation of the base material having a multilayer structure in combination with the main filter was also performed. The results are summarized in Table 1.

<Comparative Examples 1 to 7> A synthetic fiber layer was prepared as a conventional filter for a car air conditioner in the same manner as in Examples 1 to 5, and each physical property was evaluated. Comparative examples are shown in Table 2.

[0020]

[Table 1]

[0021]

[Table 2]

In Tables 1 and 2, each indication has the following meaning. PVA fiber: Full-fused binder fiber with a melting point of 60 to 70 ° C Impregnated resin: Acrylic emulsion Pressure loss: Measured at a wind speed of 40 cm / sec Thermal bending retention angle: Under a 70 ° C atmosphere with a load of 30 g / cm2 applied to the upper part Return angle of folded sheet left for 20 min (sample size: 5 * 10cm) Thermal workability of multi-layer combination base material: suitability for bonding by folding thermocompression ・ Evaluation: × unsuitable, △ acceptable, ○ good, ◎ excellent Filter characteristics of layer-combined base material: comprehensive evaluation when used as a filter ・ Evaluation: × unsuitable, △ acceptable, ○ good, ◎ excellent

From the results shown in Table 1, in the prefilters of Examples 1 to 7, the holding angle of the hot fold is 80 to 155 °, and the heat processing property of the base material in the case of the combination of multiple layers is recognized. The filter characteristics of the base material combined with the layers are also good. On the other hand, Comparative Examples 1, 4, and 5 had poor substrate thermal workability, and had streaks. In Comparative Example 2, the filter characteristics such as pressure loss were good, but the thermal workability was poor because the substrate had no rigidity. In Comparative Example 3, since the fiber diameter of the fibers used was too small, the substrate was clogged and the pressure loss was large. Further, in Comparative Examples 6 and 7, since the amount of the binder used is large, the base material is also clogged, which is not suitable for practical use in terms of filter characteristics.

[0024]

According to the present invention, by using a nonwoven fabric mixed with glass fibers produced by a wet papermaking method as a pre-filter, it is possible to make the main filter of the combined synthetic fiber layer have foldability and strength maintenance. Become. As a result, in the process of manufacturing a filter, excellent operation efficiency can be obtained when laminating multiple layers.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shunichi Amaku 2-3-2 Higashishinozaki, Edogawa-ku, Tokyo Oji Paper Co., Ltd. Edogawa Research Center

Claims (2)

[Claims] 1. A glass fiber having a fiber diameter of 6 to 13 μm is composed of 30 to 70 parts of the total weight of the base material and a synthetic fiber having a fiber diameter of 5 to 25 μm.
30-70 parts, binder fiber 1-10 parts, synthetic resin 0.1
Pre-filter base paper for car air conditioners, characterized in that it contains up to 15 parts. 2. The pre-filter base paper for a car air conditioner according to claim 1, which is produced by a wet papermaking method.