JPS61262A - Resin composition - Google Patents

Abstract

PURPOSE:To provide a resin compsn. which is inexpensive, has excellent tensile strength, flexural strength, rigidity, etc., does not cause deformation after molding and is suitable for use as a building material, by blending dry woodmeal and potassium titanate whisker with a thermoplastic resin. CONSTITUTION:10-100pts.wt. woodmeal previously dried to reduce its water content to 3-10% and 5-50pts.wt. potassium titanate whisker are mixed with 100pts.wt. thermoplastic resin such as polyethylene, polyvinyl chloride or polypropylene to obtain the desired resin compsn. The potassium titanate whisker is an acicular white crystal having an average fiber length of 10-20mum and a fiber diameter of 0.2-0.5mum prepd. from a mixture of potassium carbonate and titanium oxide by firing, melting, a hydrothermal process or a flux method, and has excellent affinity with woodmeal and excellent compatibility with molten resins.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a resin composition whose main raw material is a thermoplastic resin, and a molded article manufactured using the resin composition of the present invention includes: Compared to conventional thermoplastic resin molded products, raw material costs are reduced, physical properties such as tensile strength, bending strength, and rigidity are improved, and there is almost no deformation such as warping or sink marks after molding. It has a richly textured and luxurious design, and is widely used in applications where conventional thermoplastic resin molded products have been used, such as building materials and household goods.

(Conventional Technique Circulation) Traditionally, with the main purpose of reducing material costs, composite resin molded products have been manufactured using wood flour obtained from wood waste mixed with thermoplastic resin such as vinyl chloride as raw material. Although attempts have been made to -rb''C, the current situation is that the desired effect cannot be obtained for the reasons described below.

(Problem to be solved by the invention) (There is a limit to the mixing ratio of wood flour.

By mixing wood flour, the flow of molten resin becomes extremely poor (
As a result, workability is significantly inferior. Taking extrusion molding as an example, the mixing ratio of wood flour to 100 parts by weight of resin is 50 parts by weight.
When it reaches parts by weight, it becomes almost impossible to mold it, and the possible mixing ratio on a normal production basis is limited to parts by weight of 3ON.

Moreover, even in the case of 3 parts of ON, the shape of the molded product is currently subject to limitations. That is, for a molded article having a portion with a thickness of 3 rtmb or less, the wood flour content is further reduced to a limit of 5 parts by weight of lON. These phenomena are caused by the poor compatibility between wood flour and thermoplastic resins such as vinyl chloride.In order to improve this poor compatibility, thermosetting resins are mixed with wood flour in advance. Techniques for impregnating the raw materials have been proposed in the past, including those by the present inventors, but this method ends up increasing the raw material cost, and considering the trade-off with the effect obtained, there is no definitive solution. It's hard to call it a thing.

(11) Impact resistance is extremely poor.

It is known that when wood flour is mixed with thermoplastic resin, physical properties such as increased rigidity and reduced coefficient of thermal expansion can be obtained, but on the other hand, impact resistance is significantly inferior. It has been confirmed that it does. Taking vinyl chloride as an example, the deterioration of impact resistance due to the mixing of wood flour is as follows: when the amount of wood flour to be mixed is 10 parts by weight and 120 parts by weight, the impact resistance is 11% by weight.
I ended up working in the 30 weight division. The biggest cause of this phenomenon is the weak strength at the interface between the vinyl chloride resin matrix and the wood flour filler, and the poor dispersibility of the wood flour in the molten resin. overcrowding (
Consider that the localization of the agglomerated state and the depopulated state are significant.

(iii) The main causes are poor dispersibility of wood flour in molten resin with poor surface properties, and poor compatibility between wood flour and molten resin. The surface of a molded product that is exposed to heat becomes almost matte and hardens. Therefore, if a saturated design is not desired, it is necessary to give it a cross-like appearance by painting, etc. in a separate process. For example, an extrusion molded product made from 100 parts by weight of vinyl chloride resin mixed with 30 parts by weight of wood flour. The average surface roughness of the molded product after passing through is 05
However, the current limit for mixed substances is 2μ.

(l/) Impossible to color white Even when wood flour is mixed with thermoplastic resin, it is processed in the same way as applied to unmixed thermoplastic resin. Wood flour is exposed to extremely high temperatures. As a result, the wood flour discolors to brown, and in order to obtain a molded product that is gradually colored to white, when using titanium oxide as a white coloring pigment, it is necessary to It is necessary to add at least part by weight. If 30 parts by weight of wood flour, which already has a difficult flow, is mixed, and 50 to 60 parts by weight of titanium oxide is added, it becomes completely impossible to mold.

Vinyl chloride (for example, when wood flour is mixed with 1" eye fat, the currently highest degree of whiteness is vinyl chloride = /l/
, a composition of 100 parts by weight of i-4 fat and 20 parts by weight of wood flour I
The limit is something like %. In this case, the deterioration of impact resistance is even worse, making it almost impossible to use as a practical product.

For these reasons, when manufacturing white molded products, it is necessary to bleach the wood flour to be mixed in advance (of course, this idea is used, but this idea considerably increases the cost of raw materials, including the neutralization treatment after bleaching. It is expected that this will be the case, and it seems that it is almost impossible to use it on a commercial basis.

As mentioned above, the idea is to use a mixture of thermoplastic resin and wood flour obtained from wood waste as a raw material to obtain molded products using the same method as the normal thermoplastic resin molding method. (al) The raw material cost of the molded product obtained is reduced.

(1) Improved physical properties such as improved rigidity and decreased coefficient of thermal expansion can be obtained.

(C1 has excellent post-processing properties such as sawing, planing, and nailing.

(di) A design rich in wood texture can be obtained.

Although this technology has many attractive features, the current state of the art still leaves many problems unsolved.

Therefore, the present inventor conducted research to solve the four problems in the prior art described above, and as a result, he came up with the present invention.

(Means for solving the problem) As mentioned in Ail, the problems with the current technology caused by mixing wood flour into thermoplastic resin are roughly the following three points, except for the white swamp color problem. It can be summarized as

(1) Poor dispersibility of wood flour in bath-melted resin.

Xiang (ii) Melting wood powder and molten resin 〃(■)
The interface between wood flour and 6-fusion resin is weak in strength.

Therefore, in order to solve these three points, wood flour and main raw material B Dispersibility and thoracolysis between thermoplastic resins.

When searching for an additive that could act as an intermediary to improve the mechanical strength of the interface, potassium titanate whiskers, known as a functional filler, were found to solve the above problems. I found a solution to everything.

Potassium titanate whiskers are composed of K2C (J3 and Ti(
J2L,. Ah, □-1-4-1゜ One-drop, obtained by methods such as flux method, with an average fiber length of 10-20 mm,
It is a white sword-shaped crystal with a fiber diameter of 0.2-0.5 tn, and has the following features.

(al) Excellent heat insulation, acid resistance, and alkali resistance.

(bl itself is hydrophilic.

(Cl) Because it is fine, the increase in viscosity of the molten resin is also low.

(di Even when molding a complex shape, it can be dispersed and strengthened in every corner.

(EL) Since the terms and conditions are comparative among inorganic fibers, there is less wear and damage to processing and molding machines and molds.

(f+ It has a short fiber length and little increase in viscosity, so there is less orientation in the molded product and less warping and whiskers.

(g+ It is expensive as a filler.

Among the above-mentioned features, (al l (1-1
1+(C1, (dl, (el).The detailed reason will be described later, but the affinity with wood flour is given by its hydrophilicity, and the compatibility with molten resin is given by the property shown in (di). The improvement in processability is given by the properties shown in (al) and (cl).Also, potassium titanate whisker alone is expensive as described in (el), so it cannot be used as a fissure for thermoplastic resins. However, by combining potassium titanate whisker and wood flour, it becomes possible to mix wood flour, which is inexpensive by itself, at a high filling rate. Therefore, the utility value of potassium titanate whiskers, which had little utility value due to their high cost, will increase.

Thermoplastic resins to which the present invention can be applied include polyethylene, polyvinyl chloride, and polypropylene.

Homopolymers, copolymers, or polymer blends such as acrylonitrile-butadiene-styrene terpolymer can be considered.
Finely pulverized waste materials such as ordinary wood waste, sawn flour, particle board, fiberboard, plywood, etc. can be used, but the moisture content before mixing is 3% to 10%.
It is necessary to adjust within this range. These raw materials are premixed with potassium titanate whiskers at a ratio appropriate for the desired product design using a high-speed stirrer, and then mixed with thermoplastic resin powder or pellets to form a resin composition. obtain.

Note that the order of mixing with the resin may be arbitrary, but it is preferable to mix the wood flour and whiskers in advance and then mix them with the resin at the same time, since this will further improve the filling rate of the wood flour.

By using the same molding method (extrusion molding, injection molding, etc.) as the usual thermoplastic resin molding method for the resin composition described above, even though a large amount of wood flour was mixed,
Excellent workability, low impact resistance, smooth surface, excellent whiteness, and great freedom of shape.
It becomes possible to obtain a molded product with improved physical properties such as less warping and sink marks after molding.

(Operations) and (Effects of the Invention) Here, we will explain in what respects and for what reasons the present invention has advantages when compared to the prior art, based on the description in the (Prior Art) section. I will explain it in detail.

(1) There is a limit to the mixing ratio of wood flour.

It was already mentioned in the (Prior Art) section that this phenomenon is caused by poor compatibility between wood powder and molten resin.

However, when potassium titanate whiskers are added here, since potassium titanate whiskers themselves have hydrophilic properties and are needle-shaped crystals, they can be mixed with wood flour and potassium titanate whiskers. During mixing, the potassium titanate whiskers are selectively adsorbed on the surface of the wood flour containing several percent of water and are tightly intertwined with the cellulose fibers that protrude irregularly on the surface. It will look like it's covered. Potassium titanate whiskers themselves have good compatibility with resin, so when this mixture is melted and kneaded, the wood flour covered with potassium titanate whiskers becomes much more compatible with resin than when it is bare. becomes good and flat filling becomes possible.

Taking the current vinyl chloride resin as an example, it has been confirmed that it is possible to add up to 50 parts by weight of wood flour and 20 parts by weight of potassium titanate to 1 part by weight of resin H+00.

(11) Impact resistance is extremely poor.

The causes of this phenomenon are the weak strength at the interface between the wood flour and the thermoplastic resin, and the poor dispersibility of the wood flour in the molten resin. Considering wood flour whose surface is covered with potassium titanate whiskers, the strength of the interface between the wood flour and the potassium titanate whiskers is maintained by the intertwining of cellulose fibers and potassium titanate needle crystals. As it is known that potassium titanate and resin have good affinity to begin with, there is no problem with the strength of the interface. Furthermore, poor dispersibility is considerably improved because the surface is covered with potassium titanate whiskers.

From the above, by adding potassium titanate whiskers, it is possible to considerably suppress deterioration of impact resistance.

Taking vinyl chloride resin as an example, it has been confirmed that when whiskers are added in an amount equivalent to the amount of wood flour, the deterioration in impact resistance can be suppressed to about 4.

(IIil) This phenomenon of poor surface properties is also mainly caused by the poor dispersibility and poor compatibility of wood flour, and by adding potassium titanate whiskers, the mechanism described above can be solved. Improved.

It has been confirmed that the average surface roughness is improved by about 30-50% by adding potassium titanate whiskers in an amount that is ten times the amount of wood flour.

(iJ Impossibility of white coloring This phenomenon can also be improved by adding potassium titanate whiskers. This means that the potassium titanate whiskers, which are white in themselves, cover the surface of the wood flour. This phenomenon also supports the fact that

As mentioned above, various problems with the prior art that occur when molding a mixture of wood flour and thermoplastic resin are related to the combination of wood flour and potassium titanate whiskers in the desired ratio. can be significantly improved by In addition to the improvements mentioned above, the synergistic effect of any combination of wood flour and potassium titanate produces the following advantages.

■ When wood flour is heated to high temperatures, it produces an acidic substance commonly called wood acid. This wood acid is undesirable because it causes corrosion of molding machines, molds, etc. In fact, several methods have been proposed in the past, such as neutralizing the wood powder with alkaline gas or the like. However, in the case of the present invention, the wood flour is made of potassium titanate whiskers, which are resistant to acids and alkalis.
Since the surface is covered with silica, such adverse effects are thought to be considerably reduced.

■ Both wood flour and potassium titanate whiskers have bending strength,
Although it is well known as a filler that improves flexural modulus, dimensional stability, etc., the composition obtained by the present invention is better suited for the synergistic effect produced by combining the two than by using each alone. The above-mentioned physical property values of the molded product using the filler are better than those found in conventional fillers.

■ In terms of secondary processability, molded products are even better than those made using wood flour alone.

This seems to be caused by the fact that potassium titanate whiskers are unusually soft for inorganic fibers, which is one of their major characteristics.

The effects of the present invention and the principles that bring about the effects have been explained above, but in order to explain the present invention more clearly, specific examples will be described below. Needless to say, the present invention is not limited to this embodiment, and many different applications can be devised based on its essential principle.

(Example) The following mixtures of Formulation A, Formulation B, and Formulation C were premixed using a super mixer, respectively, and were used as raw materials, and a width of 50 words and a thickness of 50 words were prepared using a twin-screw presser. 4
Table 1 shows the results of extruding silk plates and measuring their physical properties.

(Formulation A) (Formulation B) (Formulation C) *Mix wood flour and potassium titanate in advance. (The conditions are 1500 rllll in a super mixer.
Time) *Extrusion conditions [extruder] Screw diameter 301B Temperature table for two-axis extrusion in different directions 1 *By the way, when potassium titanate is replaced with titanium oxide in the compound CIC, the whiteness is 50% and the degree of whiteness is ℃ There is.

Claims (1)

[Claims] Pre-dried wood flour and potassium titanate whiskers are mixed in a thermoplastic resin at a ratio of 10 to 100 parts by weight and 5 to 50 parts by weight, respectively, per 100 parts by weight of the resin. A resin composition characterized by: