JPS63315204A - Ligneous fiber molded body and its manufacture - Google Patents

Abstract

PURPOSE:To enable a fiber possessing a fixed quantity or more of vinyl alcohol within a polymer is processed by deforming the same further, after primary molding of the same has been performed into a sheetlike state, by performing moist heat adhesion of the fiber through vapor. CONSTITUTION:An ethylene vinyl alcohol copolymer whose ethylene mol ratio (E mol%) is 20<=E<60 and saponification degree is 98% or higher and the other thermoplastic resin are made a first and second ingredients respectively. Then the first ingredient holds 20wt.% and the first ingredient is obtained by mixing a composite fiber and ligneous fiber with each other at a weight ratio of 1:30-99:70. Then the ligneous fibers are stuck each other by melting the composite fiber under a state where the first ingredient of the same does not leave a fibrous form behind. The first ingredient is melted by receiving heat treatment at the melting point or higher of the first ingredient and among the ligneous fibers and the second ingredient of an EVC fiber are stuck strongly together, in a ligneous fiber molded body composed of constituent material like this. Then the ligneous fiber molded body where the whole of an EVOH fiber is melted is obtained by selecting a heat treatment temperature even through the same is composed of almost a similar constituent material to the above.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a wood fiber molded product used for building materials, furniture, automobile interior materials, etc. The present invention relates to a wood fiber molded article with strong stress, which can be primarily formed into a plate shape and then further deformed and processed, and a method for manufacturing the same.

(Prior Art) Wood fibers generally refer to wood, crushed products such as wheat straw, palm fruit, etc., valve precursors, etc., and have a cross section of approximately 111112 or less.1 Wood fibers are used as raw materials for synthetic wood.

Bonding wood fibers with adhesives such as thermosetting resins,
Alternatively, a technique is conventionally known in which thermoplastic fibers such as polyolefin fibers are mixed with wood fibers, the thermoplastic fibers are heated above their melting point to melt, and the wood fibers are bonded and integrated. (JP-A-50-11.81-, JP-A-52-1. OO591, JP-A-50-11.82)
(Problems to be Solved by the Invention) In such conventional techniques, when a thermosetting resin is used as an adhesive, it is extremely difficult to reshape it by hot pressing once it is completely cured. Therefore, there is a method of suppressing the degree of hardening, leaving it as a semi-hardened product, and re-molding it with heat press etc. to form the desired shape (Japanese Patent Application Laid-Open No.
1-14/+471) Semi-cured products cure or progress at room temperature, and side reactions that do not contribute to curing progress gradually, so care must be taken when storing them, and they cannot be directly cured or molded. There was a tendency for performance to be lower than that of other products. Also, in terms of applications, those using thermosetting adhesives are extremely hard and have poor plasticity, so they were not used for anything other than hardboards such as building materials and furniture materials.

If some polyolefin fibers are to be bonded by heat-melting, the mixture with wood fibers must be thoroughly dried.

The moisture content must be below 10%. This is because high moisture content may cause poor adhesion or uneven adhesion.

In addition, polyolefin polymers such as polyethylene and ethylene-vinyl acetate copolymer have poor adhesion to wood fibers, and unless they are added in a large amount (30% by weight or more), the molded product may not have sufficient plasticity. There was a drawback that the cut surface could collapse.

(Means for Solving the Problems) The present inventors have developed composite fibers (hereinafter referred to as E V
When we investigated the wet heat adhesion properties of OH fibers (abbreviated as OH fibers), we found that fibers with more than a certain amount of hinyl alcohol in their polymers have good hydrophilic properties.

The present inventors have discovered that wood fibers can be thermally bonded using water vapor, and that wood fibers can be bonded even more strongly by heating and melting the ethylene hynyl alcohol copolymer above its melting point. This led to the present invention.

That is, the first aspect of the present invention is that the ethylene molar ratio (E mol %) is 20≦E<60. The first component is an ethylene hinyl alcohol copolymer with a degree of saponification of 98% or more, the second component is another thermoplastic resin, and the first component is at least 20% by weight.
, and the first component always occupies at least a part of the fiber surface, and the wood fiber in weight ratio]:
The first component of the composite fiber is melted in a state where substantially no fiber shape remains, and the wood fibers are bonded together to form a wood fiber molded body.

The reason why the ethylene molar ratio (E%) of the EVO)l fiber needs to be 20 or more is because there is a problem with the spinnability of the EVO)(fiber).When EVO)l is E-20, the melting point of EVOH is 207
℃, and the temperature at which kelization begins if it stays for more than 5 minutes is 2.
Measured at 40.2°C. In order to stably perform melt spinning within this range, the temperature must be at least 20°C higher than the melting point, that is, 227°C, so the possible temperature range during melt spinning is 240.2-227.13.2 (°C ), and it is desirable to have at least this possible temperature range during melting and spinning, and if the temperature range is even narrower than this for composite spinning with other thermoplastic polymers, stable spinning will not be possible. This is because it is difficult.

Also, if the E value is large, the melting point of the EVOH fiber will be low or the hydrophilicity will be poor, so the E value was set to 60 to obtain the wet heat adhesive fiber which is the object of the present invention. The reason why the degree of saponification of the ethylene vinyl alcohol copolymer is 98% or more is that if it is lower than 98%, the molten resin tends to foam, resulting in more yarn breakage during the spinning process.

Ethylene vinyl alcohol copolymer and other thermoplastic resins that make EV OH fibers are polypropylene.

For polyethylene terephthalate 1, nylon 6 and nylon 66 are conveniently used to form polyethylene terephthalate.
− can also be applied. The reason for mixing these other thermoplastic resins is to improve the spinnability of EVOH fibers. %. This is because if the amount of ethylene hinyl alcohol is less than 20%, the thermal adhesion properties, which are the intended use of EVOH, will be poor.

Additionally, at least 10% thermoplastic resin is required.

If it is less than 10%, spinnability will be poor. In the EV OH fiber having such a structure, the first component must always occupy at least a part of the fiber surface, but the structure is either the first component or the sheath.

Is the cross section where the second component is the core part concentric?

Alternatively, it may be a type in which both components are arranged in parallel.

EVOH fibers are mixed with wood fibers as adhesives,
The amount is 1 to 1 to the total weight of EVOH fiber and wood fiber.
It is necessary that it be 30%.

The smaller the amount of EVOH fiber, the softer the molded product will be, the more elastic it will be, and the feel of wood. Conversely, the higher the amount of EVOH fiber, the harder the molded product will be, with a smoother surface and higher strength. Become something.

If the content of E V OI-1 fibers is less than 1%, wet heat adhesive curing will be insufficient and bending stress and abrasion resistance will be poor, making it impossible to put it to practical use. Moreover, if it is more than 30%, it is not preferable because the first component of the EVOH fiber, which does not melt, will stick to the hot plate or hot roll when heat-treated to a temperature higher than the melting point of the EVOH fiber.

In the wood fiber molded article of the first invention made of such constituent materials, the first component melts through heat treatment at its melting point and strongly adheres between the wood fibers and the second component of the EVOH fiber. There is.

Next, a wood fiber molded body made of substantially the same constituent materials as in the first invention, but in which the entire EV OH fiber is melted by selecting the heat treatment temperature, will be explained.

The second aspect of the present invention is that the ethylene molar ratio (E mol%) is 20≦E<60. The first component is an ethylene vinyl alcohol copolymer with a degree of saponification of 98% or more, and the second component is polypropylene, the first component accounts for at least 20% by weight, and the first component always occupies at least a part of the fiber surface. The weight ratio of composite fiber and wood fiber is 1.30 to 99.
The composite fibers are mixed at a ratio of near 0, and the composite fibers are melted to a state where substantially no fiber shape remains, and the wood fibers are bonded together to form a wood fiber molded body.

The second component of the E V OH fiber used in the second invention is polypropylene. Polypro(10) Pyrene has a considerably lower melting point than other polymers of the second component, and may melt depending on the processing temperature, but
The invention takes advantage of this point.

Polypropylene melts at 165-173°C, but when EV OH fibers are heated above this temperature range, the second component, polypropylene, melts, and at the same time, the first component, the ethylene vinyl alcohol copolymer, melts. The wood fibers are more firmly bonded by the molten material.

Next, the first one like this. The manufacturing method for obtaining a wood fiber molded article according to the second invention will be explained using the third invention.

The third invention of the present invention is the ethylene molar ratio (E mol%) or 2
0≦E<60. The first component is an ethylene vinyl alcohol copolymer with a degree of saponification of 98% or more, the second component is another thermoplastic resin, and the first component accounts for at least 20% by weight,
The first component always occupies at least 20% by weight of the fiber surface, and the first component always occupies at least a part of the fiber surface, and the wood fiber has a moisture content of 8% or more in a weight ratio of 1. A mixture is made at a ratio of 30 to 9970, and both sides of the mixture are compressed with a non-porous heat press machine and then subjected to the following first heat treatment and second heat treatment, or
A method for manufacturing a wood fiber molded article in which wood fibers are bonded together by directly performing a second heat treatment without heat treatment.

First heat treatment, T≧1.17E +51.5. T<
Heating temperature (T°C) within the range of 9E-I-245
How to heat.

Second heat treatment, T≧-1,9E +245. T<2
A method of heating to a heating temperature (T°C) within the range of 20°C.

It is.

The melting point of the first component of the EVOH fiber used in the present invention is measured to be approximately (9E + 245)Y, but even if the first component is below the melting point, in the presence of moisture, it will absorb water vapor generated by heating. Under the action of , one surface quickly swells and becomes a gel, allowing it to function as an adhesive fiber. Its temperature is (1, I7E +51.5), which is 1-.

The graph of FIG. 1 shows the relationship between the ethylene molar ratio (E mole %) of the first component of the E V OH fiber and the first heat treatment temperature and the second heat treatment temperature.

In the first heat treatment, the heating temperature is E V OH fiber melting point T
The temperature T (°C) at which the first component on the surface of the EVOH fiber becomes kelp in the presence of moisture is lower than -1,9B+245 (°C) -1,17E + 51.5 or higher. In the second heat treatment, the heating temperature is equal to or higher than the melting point of the EVOH fiber, and the temperature for stable heat treatment of the wood fiber, T
(°C) The temperature range is lower than -220.

In the first heat treatment, the first component of the EVOH fiber is swollen and gelled to exhibit its adhesive function.

Moisture is required when the heating temperature is below the melting point of the first component, but this can be achieved if the wood fibers to be bonded have about 8% moisture. If wood fibers are stored at room temperature, they usually contain about 10% moisture, so they can be thermally bonded as is, but in order to complete thermal bonding in a short time, a moisture content of about 15% or more is desirable. If the wood fiber is dry and the moisture content is less than 15%, it is sufficient to add a slight amount of moisture (13%).

Furthermore, wood fibers contain lignin, which contributes to thermal adhesion, and for this reason approximately 15%
It is desirable to have a considerable degree of presence. Note that the moisture content referred to in the present invention is measured according to JISL-1096.

In order for the first component of the EVOH fiber to swell and gel, the heated and vaporized moisture must be retained around the fiber, and the atmosphere must be maintained at a pressure higher than normal pressure at the moment. Use non-breathable materials.

□In this way, in the first heat treatment, the first component of EVOH fibers swells and becomes kelp, which bonds the wood fibers.

The parts that contribute to adhesion are the first component present on the surface of the EVOH fiber and the lignin of the wood fiber.

The strength of the molded product is weaker than that obtained by melting and bonding heat-sealable fibers.

Therefore, the first heat treatment is effective for temporarily molding the wood fiber molded product so that it is easy to handle, and the second heat treatment is performed when the temporarily molded product is further heat-treated to form a final product. The molded body subjected to the first heat treatment remains flexible,
After the second heat treatment, it is easy to pressurize and re-shape into a predetermined shape. By the second heat treatment, the first component of the EVOH fibers is completely melted and the wood fibers can be bonded more firmly.

When the second component of the EVOH fiber is a polymer with a melting point higher than 220°C, such as polyethylene terephthalate, polybutylene terephthalate, and nylon, the second component does not melt and maintains its fiber shape even after the second heat treatment. However, if the second component is polyallopyrene, it is possible to obtain either the molded product according to the first invention or the second invention depending on the heating temperature.

When polypropylene is heated above its melting point of 165° C., it melts and cannot maintain its fiber shape. The ethylene molar ratio (6%) when 165° C. is the melting point of the ethylene vinyl alcohol copolymer is determined to be 42 from the graph in FIG. Therefore, when 20≦E<42, the second component, polypropylene, is necessarily melted by the second heat treatment to form the wood molded article of the second invention.

In addition, even in the first heat treatment, if the heating temperature is higher than 165°C, the polypropylene component will melt and at the same time the ethylene vinyl alcohol copolymer component will swell and become a kelp. Glue.

When 42≦E<60, the melting point of the ethylene vinyl copolymer is lower than 165°C, so the temperature (T°C) subjected to the second heat treatment is
(-1,96E+
245)≦T<165, the wood fiber molded article of the first invention can be obtained.

(Effect of the invention) As described above, the wood fiber molded article according to the present invention is an EVOH
Since the first component of the fiber or the entire EVOH fiber is melted to bond the wood fibers together, the bending stress of the molded product is high, making it suitable for building materials, furniture, etc. 6 In addition, the molding method is two-step. By separating, an accelerated molded product is first obtained, which improves the convenience of storage and transportation, and from this, the desired molded product can be easily obtained by reheating.

For the embodiments of the present invention, E=38 as EVOH fiber.
．． MFR=40g/10min (, JIS K 721
0.230℃, 2.16kg load) ethylene vinyl alcohol copolymer as the first component, MFR-55g /
1.0 minute polypropylene was used as the second component, and the component ratio was 5.
A sheath-core type composite fiber with a sheath of the first component and a core of the second component at a ratio of 0:50 was melt-spun and subjected to drawing and machine crimping to produce short cut fibers of 2 denier and 5 mm (EVO).
H fiber-A) was used in each of the following examples.

The melting point of this EVOH fiber is 173℃ for the sheath and 16℃ for the core.
The temperature was 5°C.

(Examples 1 to 3) EVOH fiber-A and wood fiber were mixed and stirred in water at a ratio of 10:90 to form a wet mat with a moisture content of 100% (
A sheet with a fabric weight of 3.2 kg/m2 was prepared and compressed to a thickness of 1.6 mm using hot plates kept at 180°C and 200°C.

In each of the obtained molded bodies, the EVOH fiber-A is melted in both the sheath and the core, and the wood fibers are firmly bonded to each other.
Its surface was smooth.

Table 1 shows the results of measuring the bending stress of each molded body according to JIS~A-1408.

Table-1 Example Heat press temperature x time Bending stress Specific gravity 1
180°C x 5 minutes 837 kg/cm 1.02
], 80 X], 0 minutes 878 1.0
3200×10 minutes 500 1.0 (Example 4) The same wet mat as in Example 3 was subjected to a first heat treatment by pressing both sides with a smooth iron plate at 1.40° C. for 10 minutes, and hot pressing to accelerate molding. The accelerated molding body retained the shape of EVOH fibers, and one surface swelled and gelled, bonding the wood fibers together. The surface of the molded product has a slightly rough and rough feel.

The bending stress was 34-Okg/cm2.

Next, the above-mentioned accelerated molding was subjected to a second heat treatment by hot pressing at 200℃ for 10 minutes to compress it to a thickness of 1.5 mm (18). In the obtained molded body, the EVOH fiber-A is the sheath part.

The core is melted together to firmly adhere the wood fibers, and its surface is smooth, with a bending stress of 535 kg/cm2.
The specific gravity was 1.05.

In Examples 1 to 4 above, the second component of the EVOH fiber is polypropylene, but an example is shown in which polybutylene terephthalate is used as the second component.

As the E, VOH fiber, E-29 ethylene vinyl alcohol copolymer was used as the first component, polybutylene terephthalate was used as the second component, and the first component was used as the sheath part, and the second component was used in a weight ratio of 1:1. Composite fibers were spun using the components as core parts.

This was stretched and crimped in one machine to produce a short cut fiber of 2.5 denier and 5 openings (EVOH fiber-B), which was used in the following examples.

(Example 5) EVOH fiber-B and wood fiber were mixed in water at a ratio of 10.9o, and from this wet pine 1~ (fabric weight 3, 5 kg/m2) with a moisture content of 0% was prepared.

It was compressed to reduce the moisture content to 50%.

As a first heat treatment, this wet mat was sandwiched between iron plates heated to 170℃ from both sides and compressed to a thickness of 2.5 mm.
Heated for 0 minutes. The surface of the obtained accelerated molded product was rough, and the stress for one song was 290 kg/CI+2.

Next, as a second heat treatment, this accelerated molding was placed between two sides of a hot plate at 210° C. and heated for 10 minutes while being compressed to a thickness of 1.8 mm. In the obtained molded body, the surface of the EVOH fiber-B was melted to adhere the wood fiber, the surface was smooth, and the bending stress was 405 kg/cm2.

[Brief explanation of the drawing]

The drawing shows the ethylene molar ratio (
2 is a graph showing the relationship between the first and second heat treatment temperatures (E mol %) and the first and second heat treatment temperatures < T °C). Patent applicant: Daiwabo Co., Ltd. 111 → E”/

Claims (3)

[Claims] (1) Ethylene molar ratio (E mol%) is 20≦E<60,
An ethylene vinyl alcohol copolymer with a saponification degree of 98% or more is the first component, another thermoplastic resin is the second component, and the first component is
The component accounts for at least 20% by weight, and the first component always occupies at least a part of the fiber surface, the composite fiber and the wood fiber are mixed in a weight ratio of 1:30 to 99:70, A wood fiber molded article formed by melting the first component of the composite fiber so that substantially no fiber shape remains and bonding the wood fibers together. (2) Ethylene molar ratio (E mol%) is 20≦E<60,
The first component is an ethylene vinyl alcohol copolymer with a degree of saponification of 98% or more, and the second component is polypropylene, the first component accounts for at least 20% by weight, and the first component always occupies at least a part of the fiber surface. Composite fibers and wood fibers are mixed at a weight ratio of 1:30 to 99:70, and the composite fibers are fused to a state where substantially no fiber shape remains, and the wood fibers are separated from each other. A wood fiber molded body made by bonding. (3) Ethylene molar ratio (E mol%) is 20≦E<60,
An ethylene vinyl alcohol copolymer with a saponification degree of 98% or more is the first component, another thermoplastic resin is the second component, and the first component is
A composite fiber in which the component accounts for at least 20% by weight and the first component always occupies at least a part of the fiber surface and a wood fiber with a moisture content of 8% or more in a weight ratio of 1:30 to 99:
A mixture is made at a ratio of 70%, and both sides of the mixture are compressed with a non-porous heat press machine and subjected to the following first heat treatment and second heat treatment, or without performing the first heat treatment,
A method for manufacturing a wood fiber molded article in which wood fibers are bonded together by directly applying a second heat treatment. First heat treatment, T≧1.17E+51.5, T<-1.
Method of heating to a heating temperature (T°C) within the range of 9E+245 Second heat treatment, T≧-1.9E+245, T<2
A method of heating to a heating temperature (T°C) within the range of 20°C.