JP2020099532A - Double molded resin tableware - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double-molded resin tableware in which an inner molded body is completely transparent and excellent in adhesion between the inner molded body and the outer molded body and the strength of the entire tableware. SOLUTION: A transparent poly α composed of other than polymethylpentene is obtained with respect to 100 parts by mass of transparent polymethylpentene consisting of 5 to 100 parts by mass of high-rigidity transparent polymethylpentene and 0 to 95 parts by mass of low-rigidity transparent polymethylpentene. -After molding the inner molded body of the composition (A) containing the olefin copolymer in a proportion of 1 to 70 parts by mass in advance, the outside of the molded body is the inorganic filler 0 with respect to 100 parts by mass of polymethylpentene. It is molded with an outer molded body made of the composition (B) contained in an amount of about 120 parts by mass. [Selection diagram] FIG. 7

Description

The present invention relates to a double-molded resin tableware using polymethylpentene. More specifically, the present invention relates to a double-molded resin tableware having a highly transparent inner molded body using polymethylpentene and an outer molded body using polymethylpentene.

In general, resin tableware is often used as tableware in large-scale facilities such as schools, hospitals, and company cafeterias. The main reason for this is that resin tableware is lightweight, is not easily damaged, and is available at a low price with a product of stable shape and quality.

As such a resin tableware, the present applicant has proposed a double-molded resin tableware using polymethylpentene having excellent heat resistance (see Patent Document 1).
It has an inner molding made of a composition (A) containing polymethylpentene and polypropylene and an outer molding made of a composition (B) containing polypropylene and/or an inorganic filler in addition to polymethylpentene. Double-molded resin tableware.

Since the inner molded body has a certain degree of transparency, the appearance and appearance from the inside of the tableware are improved by decorating the outer side of the inner molded body with a pattern or the like. It was possible to increase the added value of tableware as a product.
However, if the transparency of the inner molded body is increased, the adhesion between the inner molded body and the outer molded body is deteriorated, and the strength of the whole tableware is deteriorated.
Therefore, when commercializing this double-molded resin tableware, it is necessary to give priority to solving the problem of the physical properties, so that the inner molded body is slightly clouded and the transparency is insufficient. There was a problem.
That is, in the technical field of double-molded resin tableware using polymethylpentene, the inner molded body is completely transparent, and the adhesion between the inner molded body and the outer molded body and the strength of the entire tableware have been improved. It was not possible to obtain a superior product.

Japanese Patent No. 5366122

In view of the above circumstances, the present invention provides an inner molded body comprising a composition (A) containing transparent polymethylpentene containing a highly rigid transparent polymethylpentene as an essential component and a transparent polyα-olefin copolymer, and polymethyl By using the double-molded resin tableware having the outer molded body molded with the composition (B) containing the penten and the inorganic filler, the inner molded body is completely transparent and the inner molded body and the outer molded body are It is an object of the present invention to provide a double-molded resin tableware having excellent adhesion and strength of the tableware as a whole.

The present invention is based on 100 parts by mass of transparent polymethylpentene consisting of 5 to 100 parts by mass of high-rigidity transparent polymethylpentene and 0 to 95 parts by mass of low-rigidity transparent polymethylpentene, and transparent poly α other than polymethylpentene. -After preforming an inner molding made of the composition (A) containing the olefin copolymer in a proportion of 1 to 70 parts by mass, the outer side of the molding is 100 parts by mass of polymethylpentene and 0 inorganic filler. Provided is a double-molded resin tableware which is molded with the composition (B) contained at a ratio of 120 parts by mass.

In the aspect of the double-molded resin tableware, it is preferable that the high-rigidity transparent polymethylpentene has a tensile elastic modulus of 150 to 3000 MPa and the low-rigidity transparent polymethylpentene has a tensile elastic modulus of 500 to 1500 MPa.

In the aspect of the double-molded resin tableware, it is preferable that the composition (B) contains an inorganic filler in a ratio of 40 to 120 parts by mass with respect to 100 parts by mass of polymethylpentene.

In the embodiment of the double-molded resin tableware, the inorganic filler is preferably at least one selected from barium sulfate, titanium oxide, talc, calcium carbonate, silica, glass and mica.

Generally, in large-scale facilities for feeding, resin tableware is often used because it is light in weight, is not easily damaged, and has a stable shape and quality at a low price.
In addition, double-molded resin tableware that uses polymethylpentene, which has excellent heat resistance, improves the appearance and appearance from the inside of the tableware by decorating the outside of the inner molded body with patterns etc. It is possible to increase the added value of resin tableware as a product.
In the prior art of double-molded resin tableware using polymethylpentene, when the inner molded body and the outer molded body have excellent adhesion and the physical properties of the tableware as a whole are excellent, the inner molded body is slightly clouded. The transparency was insufficient.
However, the double-molded resin tableware of the present invention has excellent adhesion between the inner molded body and the outer molded body, and has the physical properties of excellent strength of the whole tableware, since the inner molded body is completely transparent, Compared with the conventional double-molded resin tableware having insufficient transparency, it has an excellent appearance, and when a pattern or the like is decorated on the outside of the inner molded body, it has an effect of further excellent appearance and appearance.

In the double-molded resin tableware of the present invention, as a method for decorating the outside of the inner molded body with a pattern or the like, offset printing, screen printing, letterpress printing, pad printing, or other known decorating methods are applied. be able to.

The present invention is based on 100 parts by mass of transparent polymethylpentene consisting of 5 to 100 parts by mass of high-rigidity transparent polymethylpentene and 0 to 95 parts by mass of low-rigidity transparent polymethylpentene, and transparent poly α other than polymethylpentene. -After preforming an inner molding made of the composition (A) containing the olefin copolymer in a proportion of 1 to 70 parts by mass, the outer side of the molding is 100 parts by mass of polymethylpentene and 0 inorganic filler. It is intended to provide a double-molded resin tableware molded with the composition (B) contained in a proportion of 120 parts by mass.

The polymethylpentene used in the compositions (A) and (B) is a homopolymer of poly-4 methylpentene-1 or a copolymer thereof. As the copolymer, in addition to 4-methylpentene-1, for example, at least one comonomer such as ethylene, propylene, butene-1, hexene-1, octene-1, decene-1, tetradecene-1, octadecene-1 is used as a copolymer. It is polymerized. In the case of a copolymer, the copolymerization rate of the comonomer is preferably 10 mol% or less.

Rigidity means the degree of difficulty in dimensional change (deformation) with respect to bending or twisting force. When the deformation is small with respect to the force, it is called high rigidity, and when the deformation is large, it is called low rigidity. ..
As the index of rigidity in the present invention, the tensile elastic modulus when a type IV test piece is used in the ASTM D638 plastic test method defined by the American Society for Testing and Materials is used. Here, a high value of the tensile modulus is called high rigidity, and a low value is called low rigidity.

The composition (A), which is the material of the inner molded body, is 5 to 100 parts by mass of high-rigidity transparent polymethylpentene and 0 to 95 parts by mass of low-rigidity transparent polymethylpentene with respect to 100 parts by mass of transparent polymethylpentene. , A transparent poly α-olefin copolymer other than polymethylpentene at a proportion of 1 to 70 parts by mass.
Here, in 100 parts by mass of transparent polymethylpentene, since high-rigidity transparent polymethylpentene has the property of being excellent in heat resistance, 100 parts by mass of high-rigidity transparent polymethylpentene may be used. The rigid transparent polymethylpentene is an optional component used for the purpose of improving the strength of the inner molding, and may be 0 part by mass. Since the low-rigidity transparent polymethylpentene is flexible and excellent in strength but inferior in heat resistance, the high-rigidity transparent polymethylpentene is less than 5 parts by mass and the low-rigidity transparent polymethylpentene is If it exceeds 95 parts by mass, the heat resistance may be insufficient.

Further, since the transparent poly α-olefin copolymer has a property of improving the adhesiveness between the inner molded body and the outer molded body, when the transparent poly α-olefin copolymer is less than 1 part by mass, the adhesiveness is improved. May be insufficient, and if it exceeds 70 parts by mass, heat resistance and strength may be insufficient.

The composition (B), which is the material of the outer molded body, is contained in an amount of 0 to 120 parts by mass, preferably 40 to 120 parts by mass, with respect to 100 parts by mass of polymethylpentene.
Here, the polymethylpentene used for the outer molded body is not particularly limited, considering the appearance from the inner side of the tableware for the pattern and the like decorated on the outer side of the inner molded body, it is not necessary to be transparent, It may be opaque. The polymethylpentene preferably has high rigidity, but may have low rigidity. This is because the rigidity is improved by containing an inorganic filler, and the thickness of the outer molded body has a higher degree of freedom than the inner molded body, so by increasing the thickness, the rigidity of the entire outer molded body is improved. This is because it can be improved.

The inorganic filler may be 0 part by mass because it is an optional component mainly used for adjusting the specific gravity of the double-molded resin tableware. When the inorganic filler is 0 parts by mass, the specific gravity of the entire double-molded resin tableware may be less than 1, and the double-molded resin tableware in this case floats on water. The specific gravity of the entire double-molded resin tableware is preferably 1.04 to 1.5. Moreover, when the inorganic filler exceeds 120 parts by mass, the heat resistance and strength of the outer molded body may be insufficient.

The high-rigidity transparent polymethylpentene is a transparent polymethylpentene and includes all those having a tensile elastic modulus of more than 1500 MPa, preferably 1501 to 3000 MPa, and more preferably 1600 to 2500 MPa. Is.
When the tensile modulus is 1500 MPa or less, it is not preferable in that the difference in definition from the low-rigidity transparent polymethylpentene described later disappears, and the low-rigidity transparent polymethylpentene is lower than the high-rigidity transparent polymethylpentene. Since the heat resistance is poor, there is a possibility that the double-molded resin tableware excellent in heat resistance, which is the premise of the present invention, cannot be obtained.
If the tensile modulus is too high, for example, much higher than 3000 MPa such as 10,000 MPa, a problem may occur in compatibility with the low-rigidity transparent polymethylpentene, and the strength of the inner molded body may decrease. is there.

The low-rigidity transparent polymethylpentene is a transparent polymethylpentene and includes all those having a tensile modulus of 1500 MPa or less, preferably 500 to 1500 MPa, and more preferably 600 to 1200 MPa. Is.
If the tensile elastic modulus exceeds 1500 MPa, it is not preferable because the difference in definition from the highly rigid transparent polymethylpentene disappears.
When the tensile elastic modulus is too low, for example, when it is extremely lower than 500 MPa such as 10 MPa, there is a possibility that a compatibility problem with the high-rigidity transparent polymethylpentene may occur and the strength of the inner molded body may be reduced. ..

The transparent poly α-olefin copolymer is a transparent polymer and is a copolymer of ethylene, propylene, butene-1, hexene-1, octene-1, decene-1, tetradecene-1, octadecene-1 and the like. Is.

The inorganic filler is mainly used for the purpose of adjusting the specific gravity of the double-molded resin tableware, but using a known inorganic filler for the purpose of coloring, imparting antibacterial property, improving strength, improving flame retardancy, etc. It may be, for example, barium sulfate, titanium oxide, talc, calcium carbonate, silica, glass, mica, iron oxide, zinc oxide, graphite, silver ion-supporting zeolite, carbon fiber, glass fiber, antimony oxide, aluminum hydroxide, water. You may use magnesium oxide etc. Considering the appearance from the inside of the tableware and the appearance of the pattern decorated on the outside of the inner molded body, the inorganic filler used for the outer molded body is white, transparent, or glittering barium sulfate, titanium oxide, talc. It is preferable to use at least one selected from calcium carbonate, silica, glass, and mica.

Further, the composition (B), which is a material of the outer molded body, may contain a known organic additive, if necessary. For example, a benzotriazole-based ultraviolet absorber, a phthalic acid-based plasticizer, or the like. Agent, a colorant such as an azo compound, and a poly α-olefin copolymer for improving the adhesion to the inner molding may be contained.

The wall thickness of the inner molded body is not particularly limited, but the wall thickness of the thinnest portion is preferably about 0.4 to 1.2 mm. The wall thickness of the inner molded body is appropriately selected from the viewpoints of decoration on the outer side of the inner molded body, the viewpoint of the overall wall thickness, and the like.

The wall thickness of the outer molded body is not particularly limited, but the wall thickness of the thinnest part is preferably about 1.0 to 2.0 mm. The thickness of the outer molded body is appropriately selected from the viewpoints of blending the inorganic filler, the viewpoint of the overall thickness, and the like.

The wall thickness of the whole tableware of the present invention is not particularly limited, but it is preferable that the thinnest part has a wall thickness of about 1.4 to 3.2 mm. The thickness of the whole tableware is appropriately selected according to the purpose of use of the tableware and other circumstances.

The double-molded resin tableware of the present invention is not only superior in appearance to the conventional double-molded resin tableware in which the inner molded body is completely transparent and has insufficient transparency, but also the outer side of the inner molded body. When the design is decorated with a pattern, the appearance and appearance will be even better, and the adhesiveness between the inner and outer molded bodies and the strength of the entire tableware will be excellent. It is a tableware that is preferably used in a facility that provides meals on a large scale.

It is a schematic diagram showing signs that an inner compact is molded with an injection mold. It is sectional drawing which shows the inner compact which was obtained in FIG. It is the schematic which shows a mode that the decoration was given to the outer side of the inner side molding of FIG. FIG. 4 is a schematic view showing a state where the inner molded body obtained in FIG. 3 is inserted into another injection molding die. FIG. 5 is a schematic diagram showing a state where an outer molded body is molded by the injection molding die of FIG. 4. It is sectional drawing which shows the double-molded resin tableware obtained by FIG. FIG. 6 is a perspective view showing the double-molded resin tableware obtained in FIG. 5. FIG. 7 is a schematic view showing how the inner and outer molded bodies are peeled off from each other to measure the inner and outer adhesiveness of the double-molded resin tableware of FIG. 6.

(Production of double-molded resin tableware)
Using a resin composition (A) as a molding material and an injection molding machine (M-100AD-DM 100t manufactured by Meiki Seisakusho) and a mold A shown in FIG. 1, a resin temperature of 280° C., an injection pressure of 40%, and an injection speed of 40. %, and a cooling condition of 25 seconds, an inner molded body (Sample 1) having a diameter of 127 mm, a height of 50 mm and a wall thickness of 1.0 mm shown in FIG. 2 was molded. The outer portion of this inner molded body was decorated with the print 2 shown in FIG.

This inner molded body was inserted into another mold B shown in FIG. 4 and heated to 150 to 200° C., and then the same injection molding machine was used to mold resin temperature 320° C., injection pressure 90%, injection speed 90%. Then, under a molding condition of cooling for 25 seconds, a double-molded resin tableware consisting of the inner molded body 1 and the outer molded body 3 shown in FIG. 5 and having a diameter of 136 mm, a height of 56, and a total thickness of 2.2 mm was manufactured. 6 and 7 show a cross-sectional view and a perspective view of the double-molded resin tableware (Sample 2) after mold release.

The test method in the present invention is as follows.
1. Test method (1) Transparency:
Sample 1 obtained in the production of the double-molded resin tableware is visually observed, and the transparency is evaluated according to the following evaluation criteria.
(Evaluation criteria)
◯: Completely transparent Δ: Slightly cloudy and not completely transparent ×: Not transparent

(2) Internal/external adhesion:
Using the sample 2 obtained in the production of the double-molded resin tableware, the outer edges are partially broken at equal intervals with pliers or the like, as shown in FIG. The inner molded body and the outer molded body of the broken pieces are peeled off, and the internal/external adhesion is evaluated according to the following evaluation criteria.
(Evaluation criteria)
◯: No peeling at all 10 places △: Peeling at 1 to 3 places ×: Peeling at 4 or more places

(3) Heat resistance:
Using the sample 2 obtained in the production of the double-molded resin tableware, the sample is left in a constant temperature dryer at 120° C. for a certain period of time, and the heat resistance is evaluated according to the following evaluation criteria.
(Evaluation criteria)
◯: No deterioration after 1000 hours Δ: 700 to 1000 hours deteriorated ×: Less than 700 hours deterioration

(4) Strength:
Using the sample 2 obtained in the production of the double-molded resin tableware, a steel ball is dropped onto the inner molded body from a certain height, and the strength is evaluated according to the following evaluation criteria.
(Evaluation criteria)
◯: Cracks do not occur even when the height exceeds 50 cm. Δ: Cracks occur at a height of 20 to 50 cm. x: Cracks occur when the height is less than 20 cm.

2. Raw material (1) PMP (I): high-rigidity transparent polymethylpentene, tensile elastic modulus 1900 MPa
(2) PMP (II): low-rigidity transparent polymethylpentene, tensile elastic modulus 900 MPa
(3) PMP (III): opaque polymethylpentene (4) PO: transparent poly α-olefin copolymer (5) PP: polypropylene (6) inorganic filler: barium sulfate

(Examples 1 to 4, Comparative Examples 1 to 5)
Table 1 shows the compositions of the inner molding composition (A) and the outer molding composition (B), and the results of various tests. The unit of numerical values in the composition is parts by mass.
In Examples 1 to 5 and Comparative Examples 1 to 4, the sample 1 obtained by using the inner molded body composition (A) was tested for transparency, and then the outer molded body composition (B) was further tested. The sample 2 obtained by using was tested for internal/external adhesion, heat resistance, and strength. The same outer molding composition (B) was used.
Here, in Comparative Examples 3 to 4, the transparency of the sample 1 (inner molded body) was “Δ (somewhat cloudy and not completely transparent)” or “x (not transparent)”. Since it was clear that the problems of the present invention could not be solved, the test using Sample 2 (double-molded resin tableware) was not conducted.

Regarding transparency, all of Samples 1 (inner molded body) of Examples 1 to 5 contained in the composition (A) of the present invention were “◯ (completely transparent)”. Further, Comparative Examples 1 and 2 which were not included in the composition (A) were also “◯”, but Comparative Examples 3 and 4 were “Δ (slightly cloudy and not completely transparent)” or “ X (not transparent)".

Regarding the inner and outer adhesion, heat resistance, and strength, which are tests using Sample 2 (double-molded resin tableware), all of Examples 1 to 5 using the inner molded body made of the composition (A) of the present invention were used. It was “◯” or “Δ”, and each physical property was well balanced.
However, Comparative Example 1 in which the inner molded body is composed of only one kind of PMP(I) is inferior in internal/external adhesion, and Comparative Example 2 composed of a composition containing two kinds of PMP(II) and PO is heat resistant. I was inferior in sex. As a result, Comparative Examples 1 and 2 could not satisfy each physical property in a well-balanced manner.

1. Inner molded body 2. Decoration 3. Outer molded body 4. Partially broken point 5. Gate A. Injection mold B. Injection mold

Claims (4)

5 to 100 parts by mass of high-rigidity transparent polymethylpentene and 0 to 95 parts by mass of low-rigidity transparent polymethylpentene, to 100 parts by mass of transparent polymethylpentene, transparent poly-α-olefin copolymerization other than polymethylpentene After preliminarily molding an inner molding made of the composition (A) containing the coalesced in a proportion of 1 to 70 parts by mass, the outside of this molding is 0 to 120 parts by mass of inorganic filler with respect to 100 parts by mass of polymethylpentene. A double-molded resin tableware formed by molding with an outer molded body composed of the composition (B) contained in a proportion of 1 part. The double-molded resin tableware according to claim 1, wherein the high-rigidity transparent polymethylpentene has a tensile elastic modulus of 150 to 3000 MPa and the low-rigidity transparent polymethylpentene has a tensile elastic modulus of 500 to 1500 MPa. The composition (B) contains 40 to 1 of an inorganic filler with respect to 100 parts by mass of polymethylpentene.
The double-molded resin tableware according to any one of claims 1 to 2, which is contained in a proportion of 20 parts by mass. The double-molded resin tableware according to any one of claims 1 to 3, wherein the inorganic filler is at least one selected from barium sulfate, titanium oxide, talc, calcium carbonate, silica, glass, and mica.