JP3513707B2 - Composite resin and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a composite resin, a method for producing the same, and a molded resin body.

[0002]

As is well known, sericin is a protein that is eluted into a treating solution in a silk-making process for producing raw silk from cocoons or a process for refining silk fabric. Sericin is present on the surface of raw silk that forms cocoons, and is removed from raw silk by dissolving it in hot water or hot water containing soap during the silk-making process or the refining process of silk fabrics. To be done. As described above, sericin which is eluted into the treatment liquid in the yarn making process or the refining process has no effective use, and most of it is currently discarded together with the used hot water.

As a part of material recycling, it has been attempted to mold sericin for reuse, but it is difficult to mold it as it is, and even if it is blended with other materials and molded, it can be easily blended. It was difficult.

[0004]

DISCLOSURE OF THE INVENTION The present invention aims to provide effective use of sericin, and to provide a composite material containing it, a molded article made of the same, and a method for producing the same, which are easy to mold.

[0005]

The gist of the composite resin of the present invention is to consist of a resin containing sericin. The resin may be a hot melt resin. The resin may be a water soluble resin. The resin may be a partially saponified PVA resin. The PVA resin may have a polymerization degree of 200 to 5000 and a saponification degree of 60 to 95 mol%. The content of sericin may be 0.5 to 18% by weight. The content of sericin may be 1 to 10% by weight.

Further, the gist of the resin molded product of the present invention is that it is a resin molded product made of the composite resin. The resin molded body may be in the form of a film.

The gist of the method for producing a composite resin containing sericin of the present invention is to dissolve sericin and the resin in water to form an aqueous solution, and then to remove the water from the aqueous solution by drying. .

The method for producing a composite resin containing sericin may include a step of adding a resin to an aqueous solution of sericin and dissolving the resin.

Further, the gist of the method for producing a composite resin containing sericin of the present invention is that sericin powder and
It is to knead with the melted resin.

[0010]

DETAILED DESCRIPTION OF THE INVENTION

In the present invention, sericin in the form of an aqueous solution is mixed with an aqueous solution of another resin, and an attempt is made to obtain a sericin-containing resin by drying the mixed solution, and a PVA (polyvinyl alcohol) water-soluble resin is prepared. By using
Such blending has become possible. However, the resin thus obtained is generally difficult to melt thermoforming, and in the case of forming a film, the water-containing resin must be formed into a film and then dried by a casting method,
There are problems in terms of productivity, drying cost and manufacturing cost.

In the present invention, this point was further studied thoroughly, and a melt-thermoformable sericin-containing resin could be obtained.

In the embodiment of the present invention, an aqueous solution prepared by dissolving sericin in water is used as a raw material. Alternatively, the sericin aqueous solution obtained by cocooning in the yarn making process or the sericin-containing waste liquid discharged from the refining process is used as it is.

On the other hand, as the water-soluble resin to be blended,
A PVA resin having a degree of polymerization of 200 to 5000 and a degree of saponification of 60 to 95 mol% is used. An aqueous solution of this partially saponified PVA resin is mixed with an aqueous solution of sericin to form a mixed solution. Alternatively, the PVA resin may be dissolved in an aqueous solution of sericin, and water may be further added if necessary to form a mixed solution. Next, this mixed liquid is dried to form a solid or powder.

Thus, the sericin-containing composite resin of the present invention comprising sericin and PVA resin is obtained. This sericin-containing resin is extruded from a film forming die to obtain the sericin-containing resin film of the present invention.

The sericin-containing resin film of the present invention thus obtained has a higher breaking elongation and an excellent stretchability as compared with a film made of a PVA resin containing no sericin, which is formed under the same conditions. It is difficult to tear during handling. It also has excellent hygroscopicity. Furthermore, it has excellent biodegradability. In addition, the touch of the film surface is not so dry and has a waxy feel. This is because the composite resin contains sericin, so that sericin is also present on the film surface, and the sericin present on the surface causes fine irregularities on the film surface.

As described above, the PVA resin used in the present invention has a saponification degree of 60 to 95 mol%, but 70 to 95 mol l% is a melting point of the sericin-containing resin. It is more desirable in terms of moldability. Furthermore, 7
If it is 5 to 93 mol%, the most stable melt moldability can be obtained.

The PVA resin used in the present invention has a degree of polymerization of 200 to 5000 as described above.
It is more preferable that it is from 500 to 2,000 from the viewpoint of melt moldability of the sericin-containing resin. Furthermore, 700 ~
If it is 1200, the most stable melt moldability can be obtained.

The PVA resin containing sericin, which is the composite resin of the present invention, has a sericin content of 0.5 to 18
Weight percent is preferred. When the sericin content is in this range, the breaking elongation of the film obtained from this resin is higher than the breaking elongation of the film made of the original PVA resin. If the sericin content is out of this range,
The elongation at break of the film obtained from this resin is
It is smaller than or almost unchanged from the elongation at break of the film made of VA resin. Sericin content is 1 to 10
% Weight is more preferred. When the sericin content is in this range, the elongation at break of the film obtained from this resin is significantly higher than the elongation at break of the film made of the original PVA resin. The increase in the breaking elongation due to the inclusion of sericin contributes to the improvement of the processability such as the stretchability of the composite resin.

When molding a composite resin of the present invention containing sericin, a plasticizer such as glycerin may be mixed and melt-molded. Thereby, stable melt moldability can be obtained.

If desired, the composite resin comprising the resin containing sericin of the present invention may be added with a filler generally used as a resin filler such as titanium dioxide, calcium carbonate and carbon black.

As the water-soluble resin applicable to the composite resin composed of the resin containing sericin of the present invention, in addition to the PVA-based resin, for example, polyethylene glycol (PEG) is used.
Examples of the resin include polyethylene resin (PEO) resin.

In another embodiment of the present invention, the hot-melt resin is melted and kneaded with the sericin powder to obtain a composite resin composed of the resin containing sericin.

For example, the powder of sericin and the powder of PVA resin are mixed to form a mixed powder, and the mixed powder is extruded from a die for film formation to obtain a film made of a composite resin containing sericin.

As the heat-melting resin applicable to the composite resin composed of the resin containing sericin of the present invention, PVA is used.
In addition to resin, for example, nylon 6, nylon 66, polyethylene terephthalate (PET), polyethylene resin, polypropylene resin, polybutylene terephthalate, EVOH (ethylene vinyl alcohol copolymer resin), polystyrene resin, polyvinyl chloride resin , Polyethylene oxide (PEO) and the like.

The composite resin composed of the resin containing sericin of the present invention can be melt-spun to form a fiber. The obtained fiber has excellent hygroscopicity and has a soft texture. Furthermore, it has excellent biodegradability.

From the composite resin of the resin containing sericin of the present invention, it is possible to obtain a lump-shaped injection-molded article such as a tray for food, in addition to a film and a fiber.

Films, fibers and other molded products obtained from the composite resin comprising the resin containing sericin of the present invention have excellent hygroscopicity and biodegradability as compared with the original resin.

Further, according to the present invention, since sericin can be contained in a resin such as PVA and used as a molded product, sericin which has been conventionally disposed as a waste can be recycled and utilized. This reduces waste disposal costs.

The film obtained from the composite resin of the resin containing sericin of the present invention can be used as a film for packaging foods. The injection-molded article obtained from the sericin-containing resin of the present invention can be used as a tray for food.

Example 1 As a PVA resin, a partially saponified PVA resin having a polymerization degree of 1000 and a saponification degree of 88 mol% was used. The purified cocoon was boiled in a commercially available pressure cooker for 40 minutes and then filtered with filter paper to obtain an aqueous sericin solution. The above PVA resin was added to this aqueous solution, the mixture was stirred at 80 ° C. for 1 hour, and further stirred in an autoclave.
The PVA resin was completely dissolved by heating at 15 ° C. for 15 minutes and further stirring. The PVA resin and sericin contained in the obtained aqueous solution at a weight ratio of 97: 3, so that PVA
The amount of resin input was determined. This aqueous solution was dried at 105 ° C., and the obtained lump was crushed to obtain a powder of sericin-containing resin. This powder was extruded at 210 ° C. from a die for film formation (Labo Plastomill manufactured by Toyo Seiki Co., Ltd.) to obtain a film. FIG. 1 shows the SS curve (S) of this film. Also, the standard condition of this film (20 ℃,
The moisture absorption rate at 65% RH) was 5.2%.

This film was buried in soil for 2 months and taken out, and the breaking strength and breaking elongation were measured. Due to biodegradation of the film, the breaking strength was reduced to about 1/4 of the original film. The breaking elongation decreased by more than 40%.

Comparative Example 1 A film made of PVA resin alone was obtained in the same manner as in Example 1 except that water was used instead of the sericin aqueous solution as the liquid for charging the PVA resin, and the aqueous solution was made of PVA resin only. It was The SS curve (P) of this film is shown in FIG. The S-S curve (S) is the S-S curve (P).
It has a gentle initial rise and a large elongation at break compared to. The S-S curve (S) is the S-S curve (P).
The initial yield point, which is seen at a strain of 20% or more, is not observed, and gentle stretching is performed. Table 1 shows this PVA resin film and the sericin-containing PV of Example 1.
The values of the breaking strength and the breaking elongation of the A resin film are shown.

[0034]

[Table 1]

The standard condition of this film (20 ° C., 6
The moisture absorption rate at 5% RH) was 3.8%. The film was buried in soil for 2 months and taken out, and the breaking strength and breaking elongation were measured. Due to biodegradation of the film, the breaking strength was reduced to about 1 / 2.2 of that of the original film. The breaking elongation decreased by more than 3.3%, but the breaking strength and the breaking elongation did not decrease as much as in Example 1.

Example 2 A powder of PVA resin similar to the resin used in Example 1 and a powder of sericin obtained by the same method as in Example 1 were used.
Mixed in a weight ratio of 7: 3 to obtain a mixed powder. This mixed powder was extruded in the same manner as in Example 1 to obtain a film. The S-S curve of the obtained sericin-containing resin film was almost the same as the S-S curve (S) of Example 1.

Example 3 As a sericin aqueous solution, a sericin-containing waste liquid (sericin concentration: 1.5
(Wt%) was used, and a resin film containing sericin was obtained in the same manner as in Example 1. This film had a breaking strength of 35.1 MPa and a breaking elongation of 240.1%.

Example 4 An aqueous solution of sericin obtained in the same manner as in Example 1,
A partially saponified PVA resin having a degree of polymerization of 2000 and a degree of saponification of 88 mol% was mixed and stirred, and the obtained gel solution was dried and crushed to obtain a powder of a sericin-containing resin.
By changing the input amount of PVA resin, a plurality of types of sericin-containing resin powders having different sericin contents were prepared. Films were formed from this powder for each sericin content.
Molding was performed by a hot pressing method, and the crushed material was obtained by pressing at 230 ° C. for 3 minutes. FIG. 2 is a graph showing the relationship between the breaking strength and the breaking elongation of the obtained film and the sericin content (% by weight) with respect to the sericin-containing resin. In the present specification, the sericin content is the weight of the sericin-containing resin Wj, and the weight of the sericin contained therein is Ws.
Means a value represented by (Ws / Wj) × 100.

As is apparent from FIG. 2, the sericin-containing resin film having a sericin content of about 18% by weight or less had a higher breaking elongation than the film made of the original resin containing no sericin. That is, the breaking elongation of the film could be increased by incorporating sericin. When the sericin content was in the range of 1 to 10% by weight, the elongation at break could be remarkably increased as compared with the film made of the original resin containing no sericin.

Example 5 The sericin powder obtained in the same manner as in Example 1 and PE resin powder were mixed at a ratio of 3:97 (weight ratio), and a tray was formed by an injection molding machine at a mold clamping pressure of 1000 kg / cm 2. It was molded into a shape. This molded tray had hygroscopicity and could be suitably used for food packaging.

[0041]

The composite resin made of the resin containing sericin according to the present invention has improved hygroscopicity as compared with the original resin and can be easily molded by hot melt molding.
In addition, it has a silky moist and good touch without a slimy feel. Furthermore, it has biodegradability.

The composite resin composed of the PVA resin containing sericin obtained by the present invention has a large breaking elongation and excellent moldability.

According to the present invention, a composite resin composed of a resin containing sericin can be easily produced.

According to the present invention, sericin which is a waste can be recycled and used.

[Brief description of drawings]

FIG. 1 is an SS curve of a PVA resin film containing sericin and a PVA resin film not containing sericin.

FIG. 2 is a graph showing the relationship between the content of sericin in PVA resin, the elongation at break of the film, and the breaking strength.

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08J 5/00 C08L 1/00-101/16

Claims (11)

(57) [Claims] 1. A water-soluble resin containing sericin ,
A composite resin that can be melt thermoformed . 2. The composite resin according to claim 1, wherein the water-soluble resin is a heat-meltable resin. 3. The water-soluble resin is partially saponified PV
It is A resin, The composite resin of Claim 2 characterized by the above-mentioned. Wherein the PVA resin, composite resin of claim 3, degree of polymerization of 200 to 5,000, saponification degree is characterized by a 60 to 95 mol%. 5. The sericin content of 0.5 to 18
It is weight%, The composite resin of Claim 3 or 4 characterized by the above-mentioned. 6. The composite resin according to claim 5 , wherein the content of the sericin is 1 to 10% by weight. 7. A resin molded article made of a composite resin according to any one of claims 1 to 6. 8. A resin molded article according to claim 7, characterized in that the full Irumu shape. 9. A crosslinking agent prepared by dissolving sericin and a resin in water.
A method for producing a composite resin, which comprises forming an aqueous solution containing no water, and then removing the water from the aqueous solution by drying. 10. A resin is added to an aqueous solution of sericin to dissolve it.
And then removing the water from the aqueous solution by drying, the method for producing a composite resin containing sericin. 11. A method for producing a composite resin, which comprises kneading a powder of sericin and a melted water-soluble resin.