JPH04363214A - Molding material for deep drawing - Google Patents

Abstract

PURPOSE:To obtain the molding material for deep drawing which is capable of obtaining the deeply drawn moldings having a complex shape by hot-pressing molding and also is little in deformation due to moisture absorption even when the obtained moldings are made lightweight and is excellent in heat resistance and high in rigidity in the ligneous molding material for deep drawing used for the core material of the internal trim material of an automobile by hot- pressing molding. CONSTITUTION:The molding material for deep drawing is constituted by mixing 20-75 pts.wt. natural or synthetic fiber and 8-50 pts.wt. glass fiber, proper amount of thermosetting resin and thermoplastic resin in accordance with necessity with 100 pts. ligneous fiber.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a deep-drawing molding material, and more particularly to a wood-based deep-drawing molding material that is hot-pressed and used primarily as a core material for automobile interior materials. be.

0002

[Prior Art] This type of deep drawing molding material is a wood-based dry molding material, a so-called resin felt whose main raw material is recycled hair waste, or a thermoplastic resin which is mainly made of wood powder, pulp, etc. Thermoplastic molding materials made by mixing fiber waste, etc. are known.

0003

[Problems to be Solved by the Invention] However, when a wood-based dry molding material is deep-drawn for use as an automobile interior material, the wood fibers themselves are short fibers;
In addition, since it is a hygroscopic material in terms of its composition, when exposed to high temperature and humidity, its rigidity decreases extremely and warping occurs due to hygroscopic expansion, which poses a practical problem.

[0004] In particular, when trying to reduce weight, the degree of decrease in rigidity due to moisture absorption increases, making it difficult to satisfy the required performance for parts such as door materials and rear parcels, and furthermore, when using it as a ceiling material, Phenomena such as sagging due to deformation are noticeable.

[0005] In addition, in the case of resin felt, since its raw material composition is mainly polyester-based chemical fibers, the fibers do not have adhesive strength as they are and do not have good retention properties when mixed with an adhesive. A large amount of resin must be added compared to wood-based dry molding materials. In addition, the fiber itself is mainly used for clothing and is made to be flexible, so when trying to reduce the weight of resin felt, it is necessary to use aggregates such as jute or palm rock to increase rigidity. It is necessary to use a rigid auxiliary fiber raw material and to add a large amount of thermosetting resin, which leads to high costs.

Furthermore, in the case of thermoplastic molding materials, the specific gravity of the resin itself is around 1.0, so in order to reduce the weight, it is necessary to reduce the thickness of the molded product. It is necessary to provide reinforcement as an attachment, and therefore the production cost of the molding die is enormous, resulting in high costs. Furthermore, since thermoplastic resins melt at high temperatures, they have a fatal problem in terms of heat resistance, which limits the areas in which they can be used.

On the other hand, in recent years, thermosetting resin foams have been used as molded products, but since they do not have sufficient strength as a single unit, they must be used in combination with glass fibers, glass nets, etc., which increases the cost. The problem is that it is expensive.

[0008] According to the present invention, it is possible to obtain a deep-drawn product having a complicated shape by hot-pressing, and even when the weight of the obtained molded product is to be reduced, deformation due to moisture absorption is small.
The purpose of the present invention is to provide a molding material for deep drawing that has excellent heat resistance and high rigidity.

[0009]

[Means for Solving the Problems] The molding material for deep drawing of the present invention contains 100 parts by weight of wood fibers, 20 to 75 parts by weight of natural or synthetic fibers, and 8 to 50 parts by weight of glass fibers in appropriate amounts. The gist is that the thermosetting resin is mixed with a thermoplastic resin as required.

[0010] In the present invention, the wood fiber used is mainly a coniferous fiber obtained by steaming and defibrating wood chips, and usually has a diameter of 5 to 10 mm.

[0011] Natural or synthetic fibers include linen, cotton,
Examples include polyester, acrylic, nylon, etc., and those having a length of 20 to 60 mm are usually used.

[0012] The glass fiber has a diameter of around 10 μm,
A monofilament shape or a converged chopped shape can be used. The effect is remarkable whether the glass fiber is in the form of monofilament or chopped.

In the present invention, in the presence of a small amount of moisture, a component constituting the wood fiber exhibits the same function as a thermoplastic resin. The product should be blended with synthetic resins.

[0014] The thermoplastic resin is used when the molding material for deep drawing is made into a matte by a hot air aeration treatment method (oven method), and polyolefin resins, polyester resins, etc. are used.

[0015] As the thermosetting resin, a powder or liquid of phenolic resin is used, and is used to obtain the strength of a molded article obtained by hot-pressing the molding material.

[0016] In addition, paraffin-based water repellents and the like are used as ingredients for the deep drawing material to prevent moisture absorption.

[0017] After this material for deep drawing is made into a mat, it is deep drawn into a molded product by male and female molding for each application area, usually at around 210°C, under a pressure of 10 to 45 kg/cm2, for about 1 minute. Of course, instead of such a deep drawn product, a flat plate molded product may be used.

In the present invention, there are a hot air aeration treatment method (oven method) and a needle punching treatment method as means for matting the mixture of the deep drawing forming material having the above-mentioned raw material composition and making it easier to handle. Not particularly limited.

[0019]

[Function] In the above-mentioned wood molded article, one component of the wood fibers is plasticized in the presence of a small amount of water, and functions in the same way as a thermoplastic resin.

[0020] For this reason, although it depends on the intended use and site of use of the hot-press molded product, compared to molding materials that do not use wood fibers, the addition of a reinforcing thermosetting resin to satisfy the required physical properties is required. The amount can be significantly reduced.

Furthermore, since the glass fibers are mixed, the glass fibers function as reinforcement, and as a result, the amount of the reinforcing thermosetting resin added can be further reduced.

Furthermore, by using glass fiber, there is no reduction in rigidity when the weight of the hot-press molded product is reduced, and deformation of the molded product due to hygroscopic expansion under high temperature and high humidity can be effectively prevented.

The mixture of natural or synthetic fibers also physically entangles the deep drawing material to impart handling properties and flexibility. For this reason, deep drawing becomes possible during the next step of hot press forming. The amount of these fibers added varies depending on the molded shape.

[0024] Thermosetting resin is necessary to satisfy the required quality of the purpose of use and the part where it is used, and is usually 210
A mat-like material is transformed into a molded product by hot-pressing the deep drawing material at a temperature of about 10°C, a pressure of 10 to 45 kg/cm2, and a pressing time of about 1 minute.

[0025] Furthermore, the thermoplastic resin is indispensable when forming a material for deep drawing into a mat-like product using an oven method, and, like the above-mentioned natural or synthetic fibers, it is added to impart handling properties to the mat. In other words, this thermoplastic resin melts under ventilation conditions of 120 to 150°C when passing through an oven, and is cooled and solidified in a cooling process following the oven process, and is used as an adhesive between mat raw materials such as wood fibers and glass fibers. The function of

In the case of a needle-type mat, the above-mentioned thermoplastic resin does not need to be added because the needle punching process physically entangles the natural or synthetic fibers and makes the mat easy to handle.

[0027]

[Example 1] An example will be described below.

Example 1 To 100 parts by weight of wood fiber, 14 parts by weight of glass fiber, 21 parts by weight of thermosetting resin (phenol resin powder),
A deep drawing molding material A was prepared by mixing 7 parts by weight of a thermoplastic resin (polyester resin). Also, wood fiber
A molding material B for deep drawing was prepared by mixing 19 parts by weight of a thermosetting resin (phenol resin powder) and 6 parts by weight of a thermoplastic resin (polyester resin) with respect to 100 parts by weight.

[0029] The above two types of deep drawing forming materials A and B were flat-formed using two types of spacers, and the thickness was 2.5 mm.
Molded products A' and B' of mm were obtained.

For these molded products A' and B', the relationship between bending strength (kg/cm2) and specific gravity was plotted to obtain a graph as shown in FIG. 1(A). From this graph, it was confirmed that molded product A' containing glass fiber had higher strength than molded product B' when compared with products of the same specific gravity. It is also seen that by adding glass fiber, it is possible to prevent a decrease in strength due to weight reduction of the molded product.

Next, deep drawing forming materials A and B having the above compositions were prepared.
Molded products I and I were formed by flat plate molding to have the same thickness of 2.5 mm and specific gravity of 0.7.
In order to investigate the amount of deformation due to moisture absorption, the following tests (■) and (■) were conducted for I.

Test ■: 1 sampled from molded products I and II
A specimen measuring 00 x 300 mm was clamped at a height of 100 mm up to 50 mm on one side, and left in an environment of temperature 70°C and humidity 90% RH for 4 hours to determine the amount of deformation (sagging amount) at the tip of each specimen. : mm) was measured, molded product I
was 40 to 60 mm, while molded product II was 90 mm.
It was more than mm.

[0033] Test ■: 150 mm square specimens of molded products I and II were completely dried in a dryer at a temperature of 105°C, and then kept in an environment of 30°C and 95% RH until equilibrium moisture content was reached. It was left to absorb moisture. Then, the amount of deformation (mm) in the longitudinal direction of these specimens due to normal state (state before treatment with a dryer) → drying → moisture absorption was measured. The results are shown in Figure 1 (
B) As shown in . In FIG. 1(B), the solid line shows the change in molded product I, and the broken line shows the change in molded product II. From this result, it can be seen that the behavior due to moisture absorption is suppressed in molded article I using glass fiber.

Example 2 Four types of glass fibers with fiber lengths of 1 mm or less, 12 mm, 18 mm, and 25 mm were used for the deep drawing forming material A, and the thickness was 2 mm in the same manner as in Example 1.
．． 5 mm flat plate molded products A' were each made.

These molded products A' (specific gravity 0.85-0.
90), the bending strength (k
g), normal state→dry→lengthwise deformation due to moisture absorption (mm
), and the amount of deformation (mm) due to moisture absorption. These results are plotted and shown in Figures 2 (A) to (C).
I got it. In addition, the solid line in Fig. 2(B) indicates that the fiber length is 12 mm,
The broken line shows the results for the cases of 18 mm and 25 mm (all three types are on approximately the same line), and the case where the fiber length is 1 mm or less.

From the above results, it can be seen that the longer the glass fiber is, the greater the strength of the molded article is, and that it is effective to prevent moisture absorption and deformation under high temperature and humidity if the glass fiber is 18 mm or more.

On the other hand, when glass fibers are mixed, the longer the fibers are, the worse the dispersion becomes, and the surface of the mat of the finished deep drawing material becomes noticeably uneven, resulting in poor appearance of the molded product. Dispersion in physical properties increases. Therefore, the appropriate length of the glass fiber is determined to be 9 to 25 mm.

Example 3 In order to determine the appropriate amount of glass fiber to be added, the following experiment was conducted.

That is, deep drawing molding materials a to d were prepared using glass fibers with a length of 18 mm and in amounts of 3, 6, 9, and 12 parts by weight per 100 parts by weight of wood fibers.
were made in the same manner as in Example 1, with a specific gravity of 0.
．． Flat plate molded products a' to d' having a thickness of 2.5 mm and a thickness of 50 to 0.60 mm were produced. The raw material compositions of the deep drawing forming materials a to d are shown in Table 1.

[0040]

[Table 1]

The bending strength (bending breaking load) and the amount of deformation (mm) due to moisture absorption were measured in the same manner as in Example 1 for the flat plate molded products a' to d'. This measurement result was traced to obtain Figures 3(A) and (B).

[0042] Then, bending, which is the acceptance standard when the molding material used as a molded ceiling material for automobiles and has a basis weight of 1.3 to 1.6 kg/cm2, has a molded product specific gravity of 0.50 to 0.60. When the breaking load is 3.0 kg or more,
If a product with a deformation amount of 70 mm or less due to moisture absorption when left in an atmosphere of 70° C. and 95% RH for 4 hours is judged to be an acceptable product, it is found that the amount of glass fiber added must be 8 parts by weight or more.

[0043] Furthermore, since glass fiber is an expensive raw material, it is preferable to keep the cost as low as possible, and in view of product price, the upper limit of the amount added is 100 parts by weight of wood fiber. The amount is about 50 parts by weight.

Note that the bending breaking load and the amount of moisture absorption deformation vary depending on the amount of phenol resin powder added as the thermosetting resin. For example, molded product specific gravity 0.50-0.
The relationship between the amount of thermosetting resin added and the bending fracture load in No. 60 is as shown in FIG. 4, and as the amount added increases, the bending fracture load increases and the fracture strength of the molded product improves. In this case, if the amount of thermosetting resin added to 100 parts by weight of wood fiber is 15 parts by weight or more, the degree of improvement in the bending failure load will be slow, so the effective amount of adding thermosetting resin is 15 parts by weight. it is conceivable that.

Example 4 In the molding material A for deep drawing described in Examples 1 to 3 above, when it is thermally compressed to form a molded product, the wood fibers, glass fibers, and By appropriately setting the composition of the cured resin, the molded product can have the required strength and moisture deformation resistance.

However, if the shape of the molded product becomes complex, the compositions in Examples 1 to 3 may not be able to mold it well.

[0047] In order to solve such problems, hemp,
By mixing long fibers made of natural fibers such as cotton or synthetic fibers such as polyester, acrylic, nylon, etc., moldability can be improved. Next, an example in this case will be described.

That is, deep drawing molding materials C to E were prepared with the compositions shown in Table 2 below.

[0049]

[Table 2]

When the above-mentioned deep drawing forming materials C to E can be handled, two methods can be applied to the deep drawing forming material D: an oven method and a needle method; however, deep drawing forming materials C, Since long fibers were not mixed in E, the needle method could not be applied, and therefore only the oven method was applied.

Table 3 shows the experimental results for deep drawing products C' to E' using these deep drawing forming materials C to E. In Table 3, the round plate (■) used to examine the moldability is shown in FIG. 5(A), and the round plate (■) is shown in FIG. 5(B). In the figure, t1 to t6 are 150 and 12, respectively.
They are 0, 30, 100, 90, and 30 mm.

[0052]

[Table 3]

From the above results, when using deep drawing material D mixed with long fibers made of natural fibers such as linen, cotton, or synthetic fibers such as polyester, acrylic, nylon, etc., tensile strength, elongation rate, etc. It can be seen that the matte properties are improved overall and the moldability is good.

On the other hand, in the case of deep drawing molding material E in which a large amount of glass fiber is added, since the glass fiber is longer in shape than the wood fiber, the matte characteristics and moldability are slightly improved, but the cost is high.

The amount of long fibers added may be changed as appropriate depending on the shape of the desired final product. In other words, the more complex the shape, the more long fibers should be added. For example, if the shape of the molded product is a door with an integrated armrest, the mixing ratio of long fibers should be 50 to 100 parts by weight of wood fibers.
If the amount is 60 parts by weight, it can be sufficiently molded.

[0056] By adding long fibers in this way, it is possible to impart softness to the molding material for deep drawing and improve handling suitability, as well as impart good formability in the next process of hot pressure forming. However, the minimum amount added to maintain handleability is considered to be 20 parts by weight per 100 parts by weight of wood fiber.

On the other hand, whereas the wood fibers, which are the main raw material of the deep drawing molding material according to the present invention, are digested and have a complex fibrillated shape, the long fibers have a monotonous shape. Therefore, as described above, as the number of long fibers increases, it is necessary to increase the amount of reinforcing thermosetting resin added, which results in higher costs. Therefore, in consideration of manufacturing costs, the upper limit of the amount of long fibers added is determined to be 75 parts by weight per 100 parts by weight of wood fibers.

[0058]

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a deep-drawn product having a complicated shape by hot-pressing, and it is also possible to reduce the weight of the obtained molded product. It is possible to provide a molding material for deep drawing that has little moisture deformation, excellent heat resistance, and high rigidity.

[Brief explanation of the drawing]

[Figure 1] (A) is a graph showing the relationship between specific gravity and bending strength of a flat plate molded product obtained by thermoforming the deep drawing molding material in Example 1, and (B) is a graph showing the relationship between the specific gravity and bending strength of the flat plate molded product. It is a graph showing the relationship between the rate and the amount of deformation.

[Figure 2] (A) is a graph showing the relationship between the length of glass fiber used in the molding material for deep drawing and the bending strength of the hot plate molded product, and (B) is the graph showing the moisture absorption rate and deformation of this flat plate molded product. (C) is a graph showing the relationship between the glass fiber length and the amount of deformation in a flat plate molded product.

[Figure 3] (A) is a graph showing the relationship between the amount of glass fiber added in the molding material for deep drawing and the bending strength of the hot-compacted plate molded product, and (B) is the graph showing the amount of glass fiber added and the amount of deformation. This is a graph showing the relationship between

FIG. 4 is a graph showing the relationship between the amount of thermosetting resin (phenol resin) added in a molding material for deep drawing and the bending fracture strength of a hot-compression plate molded product.

FIGS. 5A and 5B are explanatory diagrams of deep drawing shapes in Example 4, respectively.

Claims (1)

[Claims] Claim 1: 100 parts by weight of wood fibers, 20 to 75 parts by weight of natural or synthetic fibers, 8 to 50 parts by weight of glass fibers, an appropriate amount of thermosetting resin, and if necessary, thermoplastic resin. A molding material for deep drawing characterized by being mixed.