JPH06240072A - Polyolefin resin composition filled with cellulosic material - Google Patents

Abstract

PURPOSE:To obtain a resin composition which can be thermoformed into a molding free from surface roughness even when it contains moisture by kneading a mixture of a polyolefinic resin containing an olefinic resin modified with an unsaturated carboxylic acid with a cellulosic filler. CONSTITUTION:The polyolefinic resin containing an olefinic resin modified with an unsaturated carboxylic acid is the one containing an unsaturated carboxylic acid component (e.g. maleic anhydride) as the comonomer component for the olefin, and its content is 0.005-25wt.%. When this resin contains a copolymer of an olefin with another olefin, the content of the subsidiary olefin is 0.5-20wt.%. Although the case, where an unmodified olefinic resin is used as the main component and an olefinic resin modified with an unsaturated carboxylic acid is used as the subsidiary component, is desirable from the viewpoint of cost, the melting point of the resin as the main component should be 50 deg.C or below. The cellulosic filler (e.g. cellulosic fiber of a length of 1mm or below) at least 80% of which pass a 100-mesh screen is added in an amount of 20-80wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellulosic filler-containing polyolefin resin composition which is excellent in thermoformability such as press forming, vacuum forming and plug assist vacuum forming when processed into a sheet.

[0002]

2. Description of the Related Art A thermoforming sheet in which a cellulosic filler is mixed with a polyolefin resin is disclosed in Japanese Patent Publication No.
No. 8462 discloses a vacuum forming sheet containing a polyolefin resin and a wood powder which is a cellulosic material and having a water content adjusted to 0.5% by weight or less. The known invention has an object to obtain a molded product having no surface roughness at the time of molding the sheet by setting the water content in the sheet to 0.5% by weight or less. In the present invention, a cellulose-based filler such as wood powder is considerably dried and then mixed with a polypropylene-based resin to obtain a composite sheet. However, in the case of the present invention, the cellulose-based filler easily absorbs moisture. Therefore, there is a problem that in order to perform thermoforming or the like with the moisture content of the composite sheet being 0.5% by weight or less, it must be immediately after the production of the composite sheet. If you want to obtain a good molded product by thermoforming some time after manufacturing the composite sheet, carefully cover the composite sheet with a highly moisture-proof bag to maintain the moisture content of the composite sheet at the above level. In addition, there is a management burden such that the desiccant must be put in the bag. Moreover, in this case, if the bag is torn, it becomes difficult to maintain the water content of the composite sheet at the above level.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and when the sheet is processed, even if the sheet contains a water content exceeding 0.5% by weight, heat An object of the present invention is to provide a polypropylene-based resin composition containing a cellulose-based filler that does not cause surface roughness during molding.

[0004]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, according to the present invention, it is composed of a mixture of an unsaturated carboxylic acid-modified olefin resin-containing polyolefin resin and a cellulosic filler, and the melting point of the main component polyolefin resin in the polyolefin resin is 1
Provided is a polyolefin-based resin composition containing a cellulosic filler, which is 50 ° C. or lower.

The unsaturated carboxylic acid-modified polyolefin resin (hereinafter also simply referred to as modified olefin resin) used in the present invention contains an unsaturated carboxylic acid component as a copolymerization component for olefin. Such a modified polyolefin resin can be obtained by random copolymerization or block copolymerization of an olefin such as propylene or ethylene and an unsaturated carboxylic acid. In this case, two or more olefins may be copolymerized, if desired. Further, it can be obtained by graft copolymerizing an unsaturated carboxylic acid with an olefin homopolymer or a random or block copolymer of an olefin and another olefin. In the present invention, it is preferable to use a polypropylene-based resin or a polyethylene-based resin obtained by graft-copolymerizing an unsaturated carboxylic acid. As the unsaturated carboxylic acid used as the copolymerization component for the olefin, various conventionally known ones can be used. As such, for example, maleic acid, nadic acid anhydride, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, mesaconic acid, angelic acid, sorbic acid, acrylic acid, maleic anhydride, itaconic anhydride, citraconic anhydride. Examples thereof include acids and derivatives of these metal salts, and maleic anhydride is particularly preferable. In the modified olefin resin used in the present invention, the content of the unsaturated carboxylic acid component is 0.005 to 25% by weight,
It is preferably 0.01 to 20% by weight. When this resin contains a copolymer of an olefin and another olefin, the content of the olefin as a secondary component is 0.5 to 20% by weight, preferably 1.0 to 15% by weight.

As the polyolefin resin used in the present invention, a modified olefin resin alone or a mixture of this and an unmodified polyolefin resin can be used. Examples of the modified polyolefin resin which can be mixed include propylene and ethylene. And homopolymers of olefins such as butene or copolymers containing the above olefins as a main component. In this case, the olefin-based copolymer may be a random copolymer or a block copolymer of a main component olefin and a subcomponent olefin. The olefin content of the accessory component in the copolymer is 0.5 to 20% by weight, preferably 1.0 to 15% by weight.

As the polyolefin resin, it is preferable to use one containing an unsaturated carboxylic acid-modified olefin resin in an amount of 1.0% by weight or more, preferably 1.5% by weight or more. Further, as the polyolefin resin, when using an unsaturated carboxylic acid-modified olefin resin alone,
Alternatively, when an unmodified olefin resin is added as a main component with this as the main component, or when an unsaturated carboxylic acid-modified olefin resin is added as the main component with an unmodified olefin resin as the main component, It is most desirable in terms of cost to blend an unsaturated carboxylic acid-modified olefin resin as an auxiliary component with an olefin resin as the main component.
In any case, the melting point of the main resin is 1
Must be below 50 ° C. As a base material for such a main component resin, a random copolymer of propylene and another olefin is desirable. As such a random copolymer, use of an ethylene / propylene copolymer is most preferable, and the ethylene content thereof is about 1 to 15% by weight based on the total weight of ethylene and propylene.

In order to produce the olefin resin composition containing a cellulose filler of the present invention, first, a polyolefin resin containing an unsaturated carboxylic acid-modified polyolefin resin, which is the main component of the polyolefin resin, is a polyolefin resin. A polyolefin resin having a melting point of 150 ° C. or lower is prepared. In this case, the main component polyolefin-based resin has a melting point of 150 ° C. or lower, preferably 120 to
It must be in the range of 150 ° C and its melting point is 150
When the temperature exceeds ° C, it becomes difficult to achieve the object of the present invention.

In the present specification, the melting point of the main component polyolefin-based resin means the temperature of 3 to 7 mg of sample is raised to 220 ° C. at a rate of 10 ° C./minute by the DSC method, and then 10
Lower the temperature to 50 ° C at a rate of ℃ / min, then 10 ° C
It means the peak temperature of the endothermic curve obtained when the temperature is raised to 220 ° C. at a rate of / min. In this case, when there are a plurality of endothermic peaks, the temperature of the peak having the largest endothermic amount is adopted.

Examples of the cellulosic filler used in the present invention include various conventionally known ones containing cellulose and lignocellulose. Something like this:
Examples thereof include cellulose fiber, lignocellulosic fiber, wood pulp, refiner ground pulp, papermaking pulp, crushed waste paper, crushed wood chips, wood powder, fruit shell powder and the like. In the present invention, it is particularly preferable to use a short fibrous material having a length of 1 mm or less or a material containing 30% by weight or more of this material, and most preferably a material passing through a 100 mesh sieve at 80% by weight or more.

The composition of the present invention contains the above-mentioned polyolefin resin and a cellulosic filler at a temperature equal to or higher than the melting point of the polyolefin resin, preferably from the melting point.
It can be obtained by kneading at a temperature higher than 0 ° C. in a kneading machine such as a Banbury mixer or in an extruder within a relatively short time, and taking out or extruding to the outside. At this time, as the main component polyolefin resin, its MFR is 3.0 to 20.
When the g / 10 min (JISK 7210, Method A, condition 4) is used, discoloration of the cellulosic filler can be prevented as much as possible, and thus discoloration of the resulting composition can be prevented as much as possible. The composition of the present invention can be melt-kneaded again in an extruder and extruded into a sheet.
In this case, the cellulosic filler is used after being dried in advance so that the water content of the sheet immediately after production is 0.1% by weight or less, preferably 0.5% by weight or less. The blending amount of the cellulosic filler is 20 to 80 in all sheets.
The amount is such that the ratio is wt%, preferably 30 to 70 wt%. The thickness of the sheet of the present invention is 0.1 to 2 mm
It is preferable that the thickness is about the same. The sheet of the present invention may be a foamed sheet having an arbitrary expansion ratio by adopting a conventionally known extrusion foaming method. The sheet of the present invention can be formed into a molded product having a desired shape by thermoforming such as vacuum forming, pressure forming, and press forming. As the thermoforming temperature in this case, a temperature of 90 to 170 ° C., preferably 100 to 160 ° C. can be adopted. Since the sheet of the present invention can be thermoformed at a low temperature as described above, it is possible to prevent the surface roughness of the molded article after thermoforming and prevent the discoloration of the cellulosic filler due to heat as much as possible. .

[0012]

The cellulosic filler-containing polyolefin resin sheet of the present invention differs from conventional products in that it has a water content of more than 0.5% by weight, particularly 1 to 3% by weight, and in some cases 4%.
Even if the content is about 5% by weight, it is possible to obtain a molded product of good quality without causing surface roughness due to thermoforming.
Therefore, it is not necessary to perform thermoforming immediately after the sheet is manufactured, the period from the sheet manufacturing to the thermoforming can be extended, and the management on the hygroscopic surface of the sheet becomes easy. Further, the molded product obtained by thermoforming the sheet of the present invention,
Since low temperature molding is possible, there is an advantage that discoloration of the sheet due to discoloration of the cellulosic filler can be prevented as much as possible and the corner portion is sharply formed.

[0013]

EXAMPLES Next, the present invention will be described in more detail by way of examples. Examples 1 to 5 and Comparative Examples 1 to 2 A polyolefin-based resin and a cellulosic filler having the composition shown in Table 1 were added to a pressure kneader having a 10-liter mixing tank so that the total weight of the composition was 7 to 10 kg. After being charged and melt-kneaded under the conditions of a mixing tank temperature of 160 ° C. and a kneading time of 15 minutes, the mixture is pelletized, and the pellets are extruded (
mm single extruder), and then extruded from a T-die installed at the tip of the extruder to produce a composite sheet having a width of about 65 cm and a thickness of about 0.5 mm. Table 1 also shows these manufacturing conditions. Also, the degree of discoloration of the pellet (the color of the pellet is directly reflected in the color of the sheet) is 4
It was evaluated at the stage and shown. Next, a thermoforming test was performed using each of the obtained composite sheets. In the thermoforming test, the composite sheet was introduced to the approximate center of a heating furnace having heaters of 50 W each (the distance between the heaters was 20 cm) at the top and bottom, and after heating for a predetermined time (seconds), plug-assisted vacuum forming was performed to obtain the obtained molding. The molding state of the product was observed. The results of the thermoforming test are shown in Table 2.
Shown in. The target molded product is as shown in FIG.
Within the length a = 453 mm and the width b = 300 mm, five hemispherical article storage units 2 having the deepest depth 45 mm and the opening diameter d = 80 mm are arranged in the a direction, and the b direction. The storage units 2 are arranged in four stages in the b direction so that the positions of the storage units 2 are shifted by half between adjacent columns.

The concrete contents of the resins indicated by the symbols in the table are as follows. PP: homopolypropylene P / E (I): propylene / ethylene random copolymer with an ethylene content of 3.5 wt% P / E (II): propylene / ethylene random copolymer with an ethylene content of 4.2 wt P / E (III): Propylene / ethylene random copolymer having an ethylene content of 3.3 wt% P / E (IV): Propylene / ethylene random copolymer having an ethylene content of 3.1 wt% P / E (V): Ethylene content Is 4.1 wt% propylene / ethylene random copolymer Further, the graft ratio shown in Table 1 shows the content rate of maleic anhydride in the resin.

[0015]

[Table 1]

[0016]

[Table 2]

Reference Examples 1 to 7 Resins having a polyolefin diameter and a cellulosic filler are blended as shown in Table 3, melt-kneaded under the same conditions as in Examples 1 to 5 and then pelletized, and the pellets are put in a single extruder having a diameter of 120 mm. After melt-kneading, it was extruded from a T-die installed at the tip of the extruder to obtain a sheet having a width of 720 mm. The discharge rate at that time was set at 100 kg / hr, which is a production level. Detailed data of the polyolefin-based resin and the cellulose-based filler are shown in Table 4 and its margins.

[0018]

[Table 3]

[001]

[Table 4] [Cell-based filler used in Reference Examples 1 to 7] Pulverized pulp ... 100 mesh passage rate 90% or more

[Brief description of drawings]

FIG. 1 is a plan view showing the shape of a molded product obtained by thermoforming the sheet of the present invention.

[Explanation of symbols]

 1 molded product 2 hemispherical product storage

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Morita 2503-1 Tsuruta-cho, Utsunomiya-shi, Tochigi Residence No. 1 Building Yokoshima Building No. 201 (72) Inventor Ken Aoki 867-1, Izumizumi-cho, Utsunomiya-shi, Tochigi Prefecture Izumizumi B −201

Claims (4)

[Claims] 1. A mixture of an unsaturated carboxylic acid-modified olefin resin-containing polyolefin resin and a cellulosic filler, wherein the main component polyolefin resin in the polyolefin resin has a melting point of 150 ° C. or lower. A polyolefin-based resin composition containing a cellulose-based filler. 2. The polyolefin resin is 3 to 20 (g)
The cellulose-based filler-containing polyolefin resin composition according to claim 1, which is a mixture containing an unmodified polyolefin resin having an MFR of / 10 min) as a main component and an unsaturated carboxylic acid-modified olefin resin as an auxiliary component. . 3. The cellulosic filler is one that passes through a 100 mesh sieve in an amount of 80% by weight or more.
Alternatively, the cellulosic filler-containing polyolefin resin composition according to claim 2. 4. A cellulosic filler-containing polyolefin resin sheet comprising the composition according to any one of claims 1 to 3.