JPH0332443B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a dry molding mat suitable for deep drawing and a manufacturing method thereof. BACKGROUND OF THE INVENTION Dry molding mats made from wood pulp as a main raw material are conventionally known and are used, for example, in the manufacture of automobile interior materials, audio equipment cases, and other furniture. It is important that this type of pine satisfies the following conditions: being inexpensive, having good moldability and handling before molding, being able to provide the desired mechanical strength, and having little variation in quality. be. Wood pulp is cheap and lightweight, so
We want to mix as much as possible as the main raw material, but manufacturing felt-like mat by mixing a large amount (50% or more) of wood pulp with short fiber length (mostly 5 mm or less) is important because of its uniform dispersibility. It was considered difficult in terms of strength characteristics and pine handling properties. Therefore, the practice has been to pre-cure the adhesive (usually a thermosetting resin) by mixing 20% or more, generally about 50%, but mixing a large amount of resin in this way reduces the mat cost. Not only will it become more expensive, but the flexibility of the pine will deteriorate,
In addition, it is difficult to control the temperature, time, etc. for preliminary curing, and the curing of the resin progresses, adversely affecting the molded properties and impairing the uniformity of the quality of the molded product. In addition, in order to reduce the amount of thermosetting resin blended, various fibrous substances are added, but depending on the method of addition, the thin fibers become neps (fluffing), and in the mat. Another drawback was that the raw materials for each component were not uniformly dispersed, which resulted in a deterioration of the mat performance. The present invention was made in view of the actual state of the prior art, and its purpose is to provide a material with good dispersion uniformity and good mat handling properties, to exhibit flexible properties, and to have good fit and moldability in deep drawing dies. The object of the present invention is to provide a molding mat that can exhibit sufficient mechanical strength after molding, and to provide a method for efficiently manufacturing such a molding mat. The present invention will be explained in more detail below. The molding mat according to the present invention contains 50 to 100 parts by weight of defibrated wood pulp obtained by steaming wood chips, 10 to 30 parts by weight of natural vegetable fibers, 5 to 10 parts by weight of chemically synthetic fibers, and a thermosetting resin. It is a felt-like mat in which 5 to 20 parts by weight are uniformly dispersed and mixed, and at least one surface thereof is subjected to interfiber bonding treatment using a non-penetrating needle punch. In the present invention, wood pulp obtained by steaming and defibrating wood chips is used. Conventionally, the wood pulp used for this type of molding mat was mainly paper pulp, so the pulp itself had no adhesive effect and a large amount of auxiliary adhesive was required. In contrast, in the present invention, the wood pulp as described above is used, and since it contains natural resins (hemicellulose and lignin), it can be sufficiently effective as an adhesive if there is an appropriate amount of moisture and heat. In particular, high-temperature steamed wood pulp has a defibration mechanism in which the resin layer (hemicellulose, lignin) containing the main fibers is softened and defibrated, so compared to ordinary groundwood pulp, the resin layer is Wood fibers with a large exposed area are obtained, and in subsequent hot-press molding, the bonding area is correspondingly wide and the bonding effect is good, and the amount of supplementary synthetic resin added can be reduced. In addition, in the present invention, wood pulp is produced from wood chips,
Unlike the conventional use of waste paper or waste wool, the quality is stable and the supply amount is also stable. The amount of wood pulp added is 50~
The reason why we chose 100 parts by weight is that we want to mix in as much wood pulp as possible in order to reduce the price and weight of the mat, but if it is too much, the strength of the mat will be insufficient, and if it is too little, the wood pulp, which is the main raw material, will not be strong enough. The shortage leads to high costs, and the decrease in the natural resin component of the wood pulp makes it difficult to increase the mechanical strength after hot-press molding, and furthermore, it becomes difficult to reduce the weight of molded products. Natural vegetable fiber is used as the main skeleton material to provide strength, and is blended in an amount of 10 to 30 parts by weight. If the blending amount is higher than this, the cost will increase due to the lack of wood pulp, the main raw material, and the mechanical strength after hot pressure molding will decrease, making it necessary to increase the specific gravity of the molded product, making it impossible to reduce weight. On the other hand, if it is less, the mat strength will decrease. Such natural fibers include thick and long fibers, specifically fibers with a long fiber length.
A material of 10 mm or more and 10 denier or more is desirable, such as linen, especially jute linen. Chemically synthesized fibers compensate for the inflexibility of natural fibers as support framework materials, and also soften when heated and act as a lubricant during molding, preventing the main framework materials and wood pulp from slipping and causing pine rupture. It is added in an amount of 5 to 10 parts by weight. If it is less than 5 parts by weight, it will not be possible to effectively prevent the pine from breaking during molding, while if it is more than 10 parts by weight, it will lead to high costs due to a lack of wood pulp, the main raw material, and a decrease in mechanical strength after molding. It is. As such a chemically synthetic fiber, one having a fiber length of 3 mm or more and a thickness of 5 denier or less is used, and specifically, for example, polyester or the like is used. In addition, 5 to 20 parts by weight of a thermosetting resin is mixed as an adhesive. As mentioned above, since high-temperature steamed wood pulp is used in the present invention, the amount of the resin component to be blended may be relatively small. A further feature of the present invention is that the felt mat in which the component raw materials are uniformly dispersed is subjected to fiber-to-fiber bonding treatment using a non-penetrating needle punch. This interfiber bonding treatment by needle punching may be performed on only one side of the felt mat, but it is preferably performed on both sides.
In either case, it is important that the needle of the needle punch does not penetrate the felt mat. The needle punch method is a method in which a large number of needles with small barbs are moved up and down to pierce the pine, intertwining the fibers within the pine in a three-dimensional manner and mechanically bonding them. It is used in the production of
In the present invention, unlike the conventional method, the needle does not penetrate the mat as described above. In the present invention, when needle punching is performed on only one side, the needle piercing layer should have a depth of about 1/3 to 2/3 of the pine thickness, and both sides should be needle punched. When performing this, it is desirable to have a needle prick layer on both sides with a depth of about 1/5 to 2/5 of the pine thickness. With this structure, a layer (needle puncture layer) in which the fibers are three-dimensionally intertwined and bonded is created on the surface of the pine through the needle punching process.
The handling properties of the pine are significantly improved, which makes it possible to keep the amount of thermosetting resin to a minimum.Also, the part of the pine that is not needle-punched, that is, the fibers are arranged two-dimensionally. Since a layer (free layer) remains, this layer exhibits flexibility and fluidity that allows it to fit well into a deep drawing die during hot-pressure molding, thereby improving the molding process. It has also been found that although this type of pine is relatively thick and contains hard fibers, the occurrence of needle breakage is greatly reduced by the needle punching method, which does not penetrate the pine. The molding mat having such a structure has sufficiently satisfactory performance, and its apparent density is 0.05 to 0.20 g/cm ³
That's about it. Next, a method for manufacturing a molding mat according to the present invention will be described. The method for producing molding pine according to the present invention involves spraying and mixing a thermosetting resin into wood pulp obtained by steaming and defibrating wood chips, and adhering the thermosetting resin to the wood pulp through a drying device, and reducing the water content to 10 to 30. 55 to 120 parts by weight of wood pulp adjusted to
The mixed fibers prepared by defibrating and defibrating 5 to 10 parts by weight of synthetic fibers are mixed in a mixer, passed through a pine former to form a bulky pine, and the needles are removed from at least one side of the bulky pine. This is a method in which the fibers are bonded together by needle punching so as not to penetrate the bulky mat. In addition, the above-mentioned steam defibration treatment of wood chips is
For example, it may be carried out at a temperature of 130°C or higher. The drawings are step-by-step diagrams of the method. First, the wood chips 10 are defibrated using a steam defibration device 30.
This steamed wood pulp is produced at about 50% (wet) content, so a drying process is essential in order to make felt-like pine, and it is also necessary to dry the fine pulp uniformly. Therefore, the drying device 3 equipped with a dispersion mixing device for the steamed wood pulp
At the same time, a predetermined amount of thermosetting resin 12, which will serve as a binder, is sprinkled in a powder or liquid state.
This allows uniform dispersion of fine pulp and mixing and adhesion of thermosetting resin in one step, and by controlling the moisture content of the wood pulp after drying to 10-30%, thermosetting resin If it is a powder, its water content will evaporate, and if it is a liquid, its solvent will evaporate, thereby making it more firmly attached to the pulp. Separately, natural plant fibers 14 and chemically synthesized fibers 16 are mixed in advance using a normal cotton opening machine 34. This is to prevent the fibers from forming neps (pilling). This is because, as a result of experiments, it was found that neps occur frequently when mixed only with thin chemical synthetic fibers, but when mixed with thick and rigid natural vegetable fibers, fine fibers do not form neps. Also,
If the natural vegetable fibers 14 and the chemically synthesized fibers 16 are mixed in advance, there is an advantage that the mixing with the wood pulp can be made much more uniform than when the three types are mixed at the same time. In this way, the mixed fibers of natural vegetable fibers and chemically synthetic fibers and the wood pulp to which the thermosetting resin has been attached are sent to the metered supply mixer 36 and mixed at a predetermined ratio, and then fed into felt by the pine former 38. The paper is made into a bulky pine 18 of the shape. Thereafter, the bulky mat 18 is passed through a needle punch machine 40, and when double-sided processing is performed, first a primary needle punching process is applied to one side, and then a secondary needle punching process is applied to the other side. will be done. As mentioned above, in these treatments, the needle penetrates the mat. Since the needle does not penetrate, in addition to the above, the needle
Another advantage is that fine particles that make up the pine do not fall off during punching. The needle-punched pine is cut by cutting device 4.
2, it is cut into a predetermined shape and becomes a molding mat 22. Moreover, the cutting waste 20 generated during cutting can be used as a reused raw material. In the conventional thermal semi-curing method, the effect of the resin has deteriorated to some extent, and if it were to be recovered as a raw material, it was necessary to re-add resin corresponding to the deteriorated amount, but with the method of the present invention, the resin effect has deteriorated to some extent. Since it is not hardened, it is sufficient to simply return the cut scraps 20 to the quantitative supply mixer 36, which facilitates quality control. Examples of the present invention and comparison with the prior art are as shown in the following table.

[Table] Here, the raw materials and their blending ratios for product A of the present invention are: Wood pulp...100 parts by weight (dry equivalent) Liquid phenolic resin (resol type)
…20 parts by weight (solid content equivalent) Hemp fiber (10 denier, length 10-20 mm)…20 parts by weight polyester fiber (1.5 denier, length 3-5 mm)
...5 parts by weight, and the raw materials and their blending ratios for product B of the present invention are: Wood pulp...100 parts by weight (dry equivalent) Powdered phenolic resin (resol type)
…20 parts by weight (solid content equivalent) Hemp fiber (10 denier, length 10-20 mm)…20 parts by weight polyester fiber (1.5 denier, length 3-5 mm)
...5 parts by weight. All of them were manufactured by the method of the present invention described above. The depth of needle punching by the needle punching machine was 1/4 of the mat thickness on both sides. In the comparative product, a mixed pine original fabric made with the same raw material composition as Invention Product B was cured using the conventional heat curing method instead of needle-punch bonding.
The phenol resin was semi-cured by aeration heat treatment using a hot air dryer, and the fibers were bonded together. As is clear from the above table, the products of the present invention have high tensile strength and good moldability as molding mats, and the mechanical strength of the molded products is also significantly improved. Since the present invention is constructed as described above, it has good dispersion uniformity of raw material components and good pine handling, exhibits flexible properties, good fitability and moldability for deep drawing dies, and has sufficient mechanical strength after molding. It is possible to obtain a molding mat that exhibits mechanical strength, and also to produce such a molding mat efficiently. Furthermore, since we use the pulp of wood chips that have been defibrated by steaming, we can increase the amount of wood pulp by adopting the needle punch method, and at the same time, it is possible to reduce the amount of thermosetting resin. It provides excellent pine handling performance and product strength equivalent to or higher than conventional products. Since the needle of the needle punch is designed to prevent the needle from penetrating the pine, resin, fine pulp, fibers, etc. do not fall off from the pine during needle punching, and even though the needle is punched, A flexible pine is formed without any problems, and it has good fitability to the deep drawing die, and therefore has good moldability.
There is almost no breakage of needles, and the pine waste generated by cutting can be reused as is, which has excellent effects. Furthermore, since the natural vegetable fibers and the chemically synthesized fibers are premixed in advance, the dispersion uniformity is excellent and the mat strength is improved.

[Brief explanation of the drawing]

The drawings are step-by-step diagrams of the method of the present invention. 10...wood chips, 12...thermosetting resin,
14... Natural plant fiber, 16... Chemical synthetic fiber,
20... Matsuto for molding, 30... Steam defibration device,
32... Drying device, 34... Cotton opening machine, 36... Fixed amount supply mixer, 38... Pine foamer, 40
... Needle punch machine, 42 ... Cutting device.

Claims (1)

[Claims] 1 Wood pulp obtained by steaming and defibrating wood chips 50~
100 parts by weight, 10 to 30 parts by weight of natural vegetable fibers, 5 to 10 parts by weight of chemically synthesized fibers, and 5 to 20 parts by weight of thermosetting resin.
1. A molding mat, which is a felt-like mat in which parts by weight are uniformly dispersed and mixed, and at least one surface of the mat is subjected to inter-fiber bonding treatment using a non-penetrating needle punch. 2 Thermosetting resin is sprayed and mixed into wood pulp obtained by steaming and defibrating wood chips, and the thermosetting resin is attached to the wood pulp through a drying device, and the moisture content is reduced.
55 to 120 parts by weight of wood pulp adjusted to 10 to 30%;
Separately, 10 to 30 parts by weight of natural vegetable fibers and 5 to 10 parts by weight of chemically synthesized fibers are mixed and defibrated in advance, mixed in a mixer, and then passed through a pine former to form bulky pine. A method for producing a molding mat, which comprises needle-punching the bulky pine from at least one side of the bulky pine so that the needles do not penetrate the bulky pine, thereby bonding the fibers to each other.