JPH08216294A - Composite resin molded product for babies and its manufacture - Google Patents

Abstract

PURPOSE: To obtain a composite molded product which is safe even for resistless babies by a method wherein a joining part of a composition molded part which contains a liquid paraffin and has styrene-ethylene-propylene-styrene copolymer as main components to polypropylene resin molded product is integrated melting. CONSTITUTION: A styrene-ethylene-propylene-styrene copolymer(S-EP-S) is a block copolymeric elastomer composed of an ethylene unit and a propylene unit which are randomly bonded to a styrene unit polymer. The elastomer composition contains 51-99wt.% of S-EP-S and 1-49wt.% of polypropylene as elastomer component, and contains 01-150 pts.wt. of a liquid paraffin to 100 pts.wt. of the elastomer component. As an example for a cover of a beverage container, a molded part 10 formed of the elastomer composition and a molded part 11 consisting of polypropylene resin are integrated by melting both at a joining part 12 of both without via other resins such as adehesives or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly safe composite resin molded product suitable for use by a person having low resistance such as an infant and a method for producing the composite resin molded product for infants.

[0002]

BACKGROUND OF THE INVENTION Infants and toddlers have low resistance, and even substances that do not affect adults can cause contact skin diseases or visceral diseases. In particular, plasticizers are used in plastic products to improve their properties. Plasticizers to be added to general plastic products include phosphate ester plasticizers, phthalate ester plasticizers, fatty acid monobasic acid ester plasticizers, fatty acid dibasic acid ester plasticizers, dihydric alcohol ester plasticizers. In addition to plasticizers and oxyester plasticizers, chlorinated paraffin and chlorinated biphenyl-2
-Nitrobiphenyl, dinonylnaphthalerin, toluenesulfonic acid ethylamide, show brain, methyl abietic acid, etc. are used. Such a plasticizer essentially has low solubility in the resin forming the molded body, and floats on the surface of the molded body over time.

These compounds do not have a particularly good effect on the human body, but adults are resistant to such compounds, and even if they come into contact with extremely small amounts of the above substances on the surface of the molded body, they pose a particular problem. It will not be affected.

However, since infants have little contact with such compounds, tolerance to such compounds has not been established. Therefore, it is desirable not to add such a plasticizer to the plastic products used by infants, but it is extremely difficult to adjust the properties of the plastic product only with the resin, and the minimum amount of plasticizer required is required. You have to use it. However, in the case of infants, even if a plasticizer that does not affect adults is used, it may cause contact diseases or visceral diseases.

By the way, many infant products have a form in which a soft portion and a hard portion are intricately combined. That is, the pacifier, which is a typical example of products for infants, will be described as an example.The pacifier seat plate holds the head that an infant can put in the mouth and prevents the head from being swallowed. It is functionally necessary that the central part for fixing the to be made of a resin that is rigid to some extent, but the surrounding part needs to be soft so that an infant is not injured.

Therefore, many products for infants are formed by joining a plurality of members formed of resins having different characteristics. In such a case, a functionally hard plastic such as the center of a pacifier seat plate is used. The part that needs to be used and the part that needs to be formed of a soft polymer (elastomer) are mixed in consideration of safety for infants. Adhesion between polypropylene resin and the like, which are essentially hard plastics, and the soft polymer is not good, and for example, it is difficult to adhere them stably for a long time even if an adhesive is used. Furthermore, in the method using such an adhesive, unreacted materials, components such as a solvent may elute from the adhesive components used, and it becomes difficult to secure safety for infants. Therefore, a fitting structure is formed and each member is fitted and locked, but in this method, since the fitted parts are merely physically engaged, this fitting is performed. It may be separated from the joint and may lead to an unexpected accident.

Therefore, in the product for infants composed of a plurality of members, it is desirable not to adopt the above-mentioned methods such as bonding with an adhesive or bonding by fitting as a method of bonding the respective structural members.

As a method for joining an elastomer and a hard plastic, Japanese Patent Publication No. 2-8572 discloses that polypropylene resin is melt-injection-molded in a mold, and then a non-vulcanized thermoplastic elastomer is melt-injected to obtain polypropylene. Disclosed is a method for manufacturing a composite plastic in which a resin member and a thermoplastic elastomer member are integrally melt-molded. Specific examples of the thermoplastic elastomer used here include a block copolymer (SEB) of a styrene polymer, an ethylene polymer and a butylene polymer.
S), a block copolymer (EP) of an ethylene polymer and a propylene polymer.

However, according to this method, it is disclosed that a molded body mainly used by an adult, such as an automobile part, a building part, and an electric product, is manufactured. There is no technical idea to select the composition of the component forming the molded body while paying attention to safety on the assumption that it will be used by a person having low resistance to. The constituent units forming this SEBS are a styrene unit, an ethylene unit, and a butylene unit, and there is room for further improvement in the bondability with the polypropylene resin.

In addition, Japanese Utility Model Publication No. 3-43951 discloses that
The invention of a milking line system is disclosed, and in this publication, a hydrogenated product of a styrene-butadiene (or isoprene) copolymer can be used as a styrene-based thermoplastic elastomer, and further, a plasticizer for such a styrene-based thermoplastic elastomer. There is a description that paraffinic oil can be used as.

The elastomer component specifically described in this publication is a styrene / butadiene block copolymer (SEBS, Kraton G, manufactured by Shell Chemical Co.), which is obtained by combining this SEBS and paraffin oil. An example to use is shown. It is also described that a hydrogenated product of a styrene / isoprene copolymer is used as the styrene-based thermoplastic elastomer, but a molded body integrated with a polypropylene resin without an adhesive or the like is described at all. Not not. That is, the above-mentioned publication discloses that a milk line hose made of SEBS, polypropylene homopolymer and paraffin oil is produced by injection molding.
There is no technical idea of integrally molding a styrene-based thermoplastic elastomer and another resin without using a substance such as an adhesive which may adversely affect infants.

[0012]

It is an object of the present invention to provide a composite molded article which is safe even for infants and children who have low resistance.

A further object of the present invention is to provide a method for producing such a composite resin molding which is highly safe for infants. Another object of the present invention is to provide a method for easily and inexpensively producing the above-described composite resin molded article having high safety for infants and toddlers.

[0014]

SUMMARY OF THE INVENTION A composite resin molded product for infants of the present invention contains liquid paraffin and contains styrene / ethylene /
It is characterized in that a molded part formed of an elastomer composition containing a propylene / styrene copolymer as a main component and a molded part formed of a polypropylene resin are melt-integrated at a joint part between them.

The infant composite resin molding contains liquid paraffin and melt-injects an elastomer composition containing styrene / ethylene / propylene / styrene copolymer as a main component to form a molding portion of the elastomer composition. And a step of forming a polypropylene resin molded portion by melt-injecting a polypropylene resin into a mold in which the elastomer composition molded portion is mounted, and at the joint portion between the two, the elastomer composition and the polypropylene resin are fused. It can be manufactured by being integrated.

[0016] In addition, this baby-baby composite resin molded body contains injection molding of polypropylene resin to form a polypropylene resin molded portion, and then liquid paraffin is contained in a mold in which the polypropylene resin molded portion is mounted. An elastomer composition containing styrene / ethylene / propylene / styrene copolymer as a main component is melt-injected to form a molded part of the elastomer composition, and the elastomer composition and the polypropylene resin are melted at a joint part between them. It can be manufactured by being integrated with each other.

The elastomer composition used in the present invention contains a styrene / ethylene / propylene / styrene copolymer as a main component, and the elastomer composition may further contain polypropylene.

Styrene, ethylene, used in the present invention
Liquid paraffin can be used as a plasticizer in an elastomer composition containing a propylene / styrene copolymer as a main component. This liquid paraffin is a highly safe compound, and contains pacifiers, tableware, baby bottles, etc. used by infants and polypropylene, and a styrene / ethylene / propylene / styrene copolymer containing liquid paraffin as a plasticizer as a main component. The substance which is dangerous for infants does not elute even if it is produced with the elastomer composition.

In the composite resin molding for baby of the present invention, the molding part made of the elastomer composition containing styrene / ethylene / propylene / styrene copolymer as a main component and the molding part made of polypropylene resin are adhesive. Since it is fused and integrated without using, there is no elution of a dangerous compound from such a joint. Further, according to the method of the present invention, the elastomer composition containing styrene / ethylene / propylene / styrene copolymer as a main component, which is not essentially good in adhesiveness, and the polypropylene resin are firmly fused and integrated. be able to.

Further, in the method of the present invention, each member is not individually manufactured and assembled, but a mold in which one member is mounted is filled with a resin forming the other member and melted and integrated. Since it can be manufactured by using the above method, the process of assembling each component can be simplified by adopting the method of the present invention. Furthermore, since the styrene / ethylene / propylene / styrene copolymer is supplied at a low cost, the composite resin molded product for infants of the present invention can be easily manufactured at a low cost.

[0021]

DETAILED DESCRIPTION OF THE INVENTION Next, the composite resin molded product for infants of the present invention and the method for producing the composite resin molded product for infants will be specifically described.

FIG. 1 is a sectional view of the lid of a baby drink container which is an example of the composite resin molded product for baby of the present invention,
FIG. 2 is a perspective view of a seat plate of a pacifier which is a similar example, and FIG. 3 is a sectional view taken along line BB in FIG.

In the composite resin molding for infants of the present invention, the molding portion 10 made of the elastomer composition and the molding portion 11 made of polypropylene resin are melt-integrated at the joint portion 12 of both.

The elastomer composition forming the molded part 10 made of the elastomer composition used in the present invention contains styrene / ethylene / propylene / styrene copolymer as a main component.
The styrene copolymer may be used alone or may be mixed with other resin-based components or elastomer-based components for use. In particular, this elastomer composition preferably contains polypropylene. When the elastomer composition used in the present invention contains polypropylene, the styrene / ethylene / propylene / styrene copolymer is 51 to 99% by weight, preferably 60 to 90% by weight.
It is contained in the amount of wt%, and polypropylene is 1 to 4
It is contained in an amount of 9% by weight, preferably 10-40% by weight. The total of styrene / ethylene / propylene / styrene copolymer and polypropylene is 100% by weight.
Is. In the present invention, it is also possible to use a composition in which the content of polypropylene in the elastomer composition is less than 1% by weight. Therefore, as the elastomer composition used in the present invention, depending on the application, It is also possible to use those containing a very small amount of polypropylene or those containing no polypropylene (polypropylene content 0%).

In this elastomer composition, as the content of polypropylene increases, the molded part made of this elastomer composition becomes harder. By blending polypropylene in such an amount as described above, hardness can be imparted to this molded portion without impairing the properties of the styrene / ethylene / propylene / styrene copolymer as an elastomer.

The styrene / ethylene / propylene / styrene copolymer (S-EP-S) used in the present invention is a polymer of styrene units and a block copolymer in which ethylene units and propylene units are randomly bonded. The styrene / ethylene / propylene / styrene copolymer (S-EP-S) is usually an elastomer produced by hydrogenating a styrene / isoprene / styrene copolymer (SIS). This styrene
Ethylene / Propylene / Styrene Copolymer (S-EP-
S) has excellent elastomer properties, is highly safe, and is inexpensive. Styrene / ethylene / butylene / styrene, which is a hydrogenated product of styrene / butylene / styrene copolymer (SBS), is a substance whose name is similar to that of styrene / ethylene / propylene / styrene copolymer (S-EP-S). There is a copolymer (S-EB-S), but both are completely different substances. For example, ¹³ C-NM
Both can be clearly distinguished by measuring the R spectrum.

In the elastomer composition used in the present invention, liquid paraffin which is excellent in hygiene is used as a plasticizer. That is, among various plasticizers, liquid paraffin exhibits good plasticity to the elastomer composition, particularly styrene / ethylene / propylene / styrene copolymer, and the liquid paraffin is a general paraffin oil. Since it is a highly saturated liquid saturated hydrocarbon, it has almost no effect on the human body,
Moreover, it is tasteless, odorless and colorless and stable to light, heat and acid. Therefore, as a plasticizer for a resin that forms a member that a baby may eat, such as a pacifier seat plate, or a container for a baby that may be eluted by a plasticizer such as tableware for a baby, Liquid paraffin is preferred. In addition, since this liquid paraffin is colorless, it has the property that even if the composite resin molded product for infants is colorfully colored, its color tone is not changed by the plasticizer.

The liquid paraffin is an elastomer component (S-, which constitutes the elastomer composition used in the present invention.
Total amount of EP-S and PP optionally blended) 10
The amount is usually 0.1 to 150 parts by weight, preferably 10 to 100 parts by weight, relative to 0 parts by weight.

The liquid paraffin exhibits a particularly excellent plasticity with respect to the elastomer composition containing the styrene / ethylene / propylene / styrene copolymer, and the liquid paraffin is extremely safe. Therefore, even if an infant uses the composite resin molded product for infants containing the liquid paraffin, the infant is not affected by this. Also, this liquid paraffin is
As described above, while exhibiting good plasticity to the elastomer composition used in the present invention, the elastomer composition containing the liquid paraffin has good stability during injection molding, for example, injection molding At this time, the situation in which the elastomer composition causes baking or the like to cause defective molding is unlikely to occur. Furthermore, even if this liquid paraffin is blended, the integrity of the molding part made of the elastomer composition and the molding part made of polypropylene resin is not impaired at the joint surface.

Regarding the elastomer composition as described above
The hardness (HSA) measured by JIS-K-6301 is usually 20-1
In the range of 00, 100% modulus as measured in the same manner is usually 0.01~1.00kgf / mm ^2, the tensile strength is usually 0.50~5.00kgf / mm ^2, tensile elongation is usually Is 50
It is in the range of 0 to 1200%. Further, the compression set measured by JIS-K-6301 under the condition of 70 ° C. × 22 hours is
It is usually in the range of 20 to 100%. In addition, BS-
The impact resilience measured by 903 is usually 30-70%
Is within the range of.

Molding part 11 made of polypropylene resin
May be a homopolymer of propylene or a copolymer of a monomer copolymerizable with propylene (for example, ethylene or butadiene). Further, this polypropylene resin can also be used as a mixture with other resins as long as the characteristics thereof are not impaired. For example, in the present invention, a small amount of resin such as polyethylene can be mixed with polypropylene resin for use. The polypropylene used here is a resin, not an elastomer (soft polymer), and the crystallinity of this polypropylene resin measured by X-ray diffraction is usually 10% or more, preferably 5%.
It is 0% or more, and the glass transition temperature is usually 70 ° C or more.

The elastomer composition and the polypropylene resin may be blended with other additives which are usually blended with the resin, as long as the safety is ensured. For example, colorants, fillers, fibers, heat resistance stabilizers, weather resistance stabilizers, other plasticizers and the like can be mentioned.

The molding part 10 made of the elastomer composition and the molding part 11 made of polypropylene resin are the joint parts 12 of the two and are melted together without any other resin such as an adhesive. And are integrated. That is, microscopically, at the joint portion 12 between the two, it is considered that the elastomer composition and the polypropylene resin are integrated by forming a continuous layer at least at a part thereof. Therefore, the composite resin molded article for baby of the present invention is formed of the elastomer composition and the polypropylene resin, and does not substantially contain any other resin, and therefore, for example, the solvent of the adhesive, the unreacted monomer Such difficult-to-predict substances will not elute. Thus, the composite resin molded article for infants of the present invention is formed by forming a continuous layer of the two, for example, at the joint portion where the forming materials are different, or the surface is By closely adhering to each other, the respective molded parts are firmly joined. That is, styrene, ethylene, propylene,
Since the styrene copolymer has a propylene unit in its molecular structure, it has very good compatibility with the polypropylene resin, and joins the molded part 11 made of the polypropylene resin and the molded part 10 made of the elastomer composition. Excellent integration of both in the part 10. And when this elastomer composition contains a polypropylene resin, its integration is further improved and the joining state of both is extremely good.

In particular, in the composite resin molded product for infants of the present invention, it is preferable that the joint 12 between the molded part 10 made of the elastomer composition and the molded part 11 made of polypropylene resin is not flat. For example, as shown in FIG. It is preferable to provide a step 13 at the joint 12 between the two and to form a convex portion 14 and a concave portion 15 as shown in FIG. By doing so, the joining area between the two becomes large and the joining force between the both becomes higher.

In the composite resin molded product for infants and children of the present invention as described above, a molded part is formed by using one of the components of the elastomer composition and the polypropylene resin, and then the formed molded part is mounted. It can be manufactured by injecting the other component into a mold to form a molded part made of the other component and melting and integrating the joint part.

That is, the composite resin molded product for infants of the present invention contains (A) liquid paraffin and
A first step of melt-injecting an elastomer composition containing an ethylene / propylene / styrene copolymer as a main component to form a molded part made of the elastomer composition, and a molded part formed by the first step In the loaded mold, polypropylene resin is melt-injected to form a polypropylene resin molding part, and at the joint part of both,
Method A comprising the second step of fusion-bonding and integrating these elastomer composition and polypropylene resin; or
(B) A first step of forming a polypropylene resin molded portion by injection molding a polypropylene resin, and a mold loaded with the molded portion formed in the first step, containing liquid paraffin, and An elastomer composition containing styrene / ethylene / propylene / styrene copolymer as a main component is melt-injected to form a molded portion of the elastomer composition, and the elastomer composition and the polypropylene resin are melted at a joint portion between them. Second to wear together
Can be produced by any one of the method B;

First, the method B will be described. By the method B, a pacifier seat plate as shown in FIGS. 2 and 3, for example, can be manufactured. 4 and 5
FIG. 4 is a view showing a state when manufacturing a composite resin molded body for infants (seat plate of a pacifier) as illustrated in FIGS. 2 and 3 in a cross section taken along the line AA in FIG. 2. In manufacturing a pacifier seat plate, first, a molding member 31 made of polypropylene resin is formed using a mold 30 having a cross section as shown in FIG. 4, for example. The molding member 31 made of this polypropylene resin corresponds to 11 in FIG. Next, the member 31 is released from the mold 30. The demolded molding member 31 is loaded into another mold 35 as shown in FIG. Next, the other component, the elastomer composition, is melt-injected into the mold. The molded part formed by this elastomer composition corresponds to 10 in FIGS. 2 and 3. By injection molding in this manner, it is considered that a continuous layer composed of both components is formed at at least a part of the joint between the molded part made of the elastomer composition and the molded part made of polypropylene resin. The molding portion 32 (outer peripheral portion) made of the composition and the molding portion 31 made of polypropylene resin are integrated.

After injecting the elastomer composition in this manner, it is cooled and released from at least the molded portion of the elastomer composition until self-shape retention is exhibited, to produce the composite resin molded product for infants of the present invention. can do.

The above-mentioned method B is a method of injecting the polypropylene resin first and then the elastomer composition, but the composite resin molded article for baby of the present invention is prepared by injecting the elastomer composition from the elastomer composition. It is also possible to inject the polypropylene resin and integrate the two after forming the molded part.

That is, the method A is, for example, as shown in FIGS. 6 and 7, in the production of the composite resin molded body for infants (cup mouth) as shown in FIG.
The elastomer composition is injected from the gate A using the dies 40A and 40B having the cross section as shown in (1) to form the molding portion 42 (packing portion) made of the elastomer composition. Next, as shown in FIG. 7, the female die 40B is removed while leaving the member 42 in the male die 40A, and the male die 40A is removed.
A new female mold 40C that can form a gap for injecting polypropylene resin is installed in cooperation with. Next, the polypropylene resin in a molten state is injected from the gate B into the gap into which the polypropylene resin formed by the molds 40A and 40C is to be injected to form the molding portion 41 made of polypropylene resin. In FIG. 1, the molding portion 41 made of this polypropylene resin corresponds to 11. By injecting the polypropylene resin in this manner, it is considered that a continuous layer composed of both components is formed in at least a part of the joint between the molded part composed of the elastomer composition and the molded part composed of the polypropylene resin. The lid of the drink container, which is an example of the composite resin molded product for infants of the present invention, can be manufactured by bonding to.

Similarly, as shown in FIG. 8, in the case of a projection to which the infant composite resin molded body 51 is fitted and locked, first, for example, FIG. 8 (A) and FIG. 8 ( Using the molds 50A and 50B having a cross section as shown in B), the protrusions that are the molding parts 52 made of the elastomer composition are formed. Next, the male die 50B is removed with the member 52 left in the female die 50A, and a new male die 50C capable of forming a gap for injecting polypropylene resin in cooperation with the female die 50A is mounted. To do. Then, molds 50A and 50C
A polypropylene resin in a molten state is injected into the gap formed by. By injecting the polypropylene resin in this manner, it is considered that a continuous layer composed of both components is formed in at least a part of the joint between the molded part composed of the elastomer composition and the molded part composed of the polypropylene resin. The composite resin molded product for infants of the present invention can be manufactured by bonding to.

It should be noted that, in FIGS. 6, 7 and 8 described above, there is shown a method of molding by replacing a part of the mold without mounting the molded product at the initial stage and removing it from the mold. However, it is also possible to inject the polypropylene resin after removing the member molded in this first stage from the mold and mounting it in a completely different mold.

Other conditions in the injection molding carried out as described above are the same as those in ordinary injection molding. For example, the mold temperature is usually 10 to 50 ° C., preferably 18 to 25.
It is set within the range of ° C. The heating temperature of the elastomer composition is usually 180 to 230 ° C, and the heating temperature of the polypropylene resin is usually 180 to 230 ° C.

In addition to the pacifier seat plate, drink container lid, molded member locking member, etc., the composite resin molded product for infants and babies of the present invention includes, for example, a toothbrush for infants and teeth, etc. These infant composite resin moldings can be manufactured by any of the methods described above.

[0045]

EFFECT OF THE INVENTION In the composite resin molded product for infants of the present invention, the elastomer composition contains a styrene / ethylene / propylene / styrene copolymer as a main component, and liquid paraffin is used as a plasticizer in the elastomer composition. Since it is used, it is safe for infants with low resistance to use. Furthermore, the formed portion made of polypropylene resin and the formed portion made of the elastomer composition are not bonded by an adhesive, and they are not simply fitted together, and the polypropylene resin and the elastomer composition are continuously melted to form a continuous layer. Since it is considered that they are joined by forming the adhesive, there is no elution of the adhesive component or the like from such joined portions. Also, since both are not simply fitted,
The joining state of the two is extremely strong.

The bonding of the two is because the styrene / ethylene / propylene copolymer forming the elastomer composition has the same constitutional unit as the repeating unit derived from propylene. By adopting, it is possible to satisfactorily bond a polypropylene resin having essentially no good adhesion to an elastomer composition containing a styrene / ethylene / propylene / styrene copolymer as a main component.

Further, in the method of the present invention, each member is not individually manufactured and assembled, but a mold in which one member is mounted is filled with a resin for forming another member and melted and integrated. Since it can be manufactured by using the above method, the process of assembling each component can be simplified by adopting the method of the present invention. Furthermore, since the styrene / ethylene / propylene / styrene copolymer is supplied at a low cost, the composite resin molded product for infants of the present invention can be easily manufactured at a low cost.

[0048]

EXAMPLES Next, the present invention will be described in more detail by showing Examples of the present invention, but the present invention should not be construed as limited by these Examples. The test method for the molded article in the present invention is as follows.

The test is based on the food hygiene law, standard standards for foods, additives, etc. (Ministry of Health and Welfare Notification 370, 1959) Containers or packaging made of synthetic resin containing polyethylene as a main component (Showa 5)
It carried out as follows based on Ministry of Health and Welfare Notification No. 20).

1. Volatile substance About 0.5 g of a sample was cut out from a molded body and accurately weighed,
This is placed in a 20 ml measuring flask, and an appropriate amount of dimethylformamide is added. After the sample has dissolved, 1 ml of cyclopentanol reagent is added, followed by dimethylformamide to make 20 ml. Using this as a sample solution, the volatile substances in the monomer test method are tested.

Depending on the volatile substances measured, styrene, toluene, ethylbenzene, isopropylbenzene and
Measure each concentration of n-propylbenzene. 2. Dissolution test 1 g of a sample cut out from cadmium and lead compacts was placed in a platinum or quartz evaporation dish, 10 drops of sulfuric acid was added, and the mixture was gradually heated to evaporate most of the mass-produced material, and then dried by direct heating. Harden. Subsequently, while increasing the heat power, this is heated to about 450 ° C. to be incinerated.
The contents of the evaporating dish are moistened with sulfuric acid and heated again, and this operation is repeated until almost white ash is obtained. When the polarographic method is used, 10 ml of the electrolytic solution is added to this residue (0.2 ml of the gelatin solution is further added when the direct current polarographic is used), and the test solution is prepared by leaving it for 3 hours with occasional stirring. . When using the atomic absorption spectrophotometric method, 10 ml of 0.1 N nitric acid is added to the residue to dissolve the residue into a lead sample solution. Further, 1 ml of this sample solution is added, and 0.1 N nitric acid is added thereto to make 10 ml, to prepare a cadmium test solution.

Cadmium and lead tests are carried out on these used solutions by the polarographic method or the atomic absorption spectrophotometric method. 3. Heavy Metals Heavy metals were analyzed in test solutions prepared using 4% acetic acid as the leach solution. The conformance standard is 1 ppm or less.

4. Potassium Permanganate Consumption The consumption of potassium permanganate was measured for the test solution prepared using water as the leaching solution. The conformity standard is 10 ppm or less.

5. Evaporation residue In the test of evaporation residue, the conformity criteria of the residue are:
It is 30 ppm or less. The styrene / ethylene / propylene / styrene copolymer, polypropylene resin and liquid paraffin used in the following examples are as follows.

(1) Styrene / ethylene / propylene / styrene copolymer Septon 4055 (manufactured by Kuraray Co., Ltd.) (2) Polypropylene MS670 (manufactured by Tokuyama Soda Co., Ltd.) (3) Liquid paraffin PW-90 (Idemitsu Kosan Co., Ltd.) (Made by)

[0056]

Example 1 An elastomer composition containing 80 parts by weight of a styrene / ethylene / propylene / styrene copolymer, 20 parts by weight of polypropylene, and 50 parts by weight of liquid paraffin as a plasticizer was prepared. Separately, a crystalline polypropylene resin (yellow content was kneaded) was prepared.

The elastomer composition is injected from the gate A into a mold in which a gap for forming the packing portion of the screw lid shown in FIG. 6 is injected, and the center of the inner peripheral surface of the portion where the screw lid is to be formed is formed. The packing part was formed in the part. The mold temperature is cooled, the upper portion 40B is replaced with 40C as shown in FIG. 7, and a yellow polypropylene resin is injection-molded from the gate B to form the outer peripheral portion of the screw lid of the baby drink container, After the mold was cooled to cure the screw lid, the mold was removed.

When the joint between the polypropylene resin molded portion and the elastomer molded portion of this molded body was observed, it was found that both were integrated at the boundary surface and they could not be separated.

Regarding the molded article produced in this manner, as described above, the standard of food hygiene law, foods, additives, etc. (Showa 34 Ministry of Health and Welfare Notification 370) Container or container made of polyethylene as a main component A material test and a dissolution test were performed based on the packaging (Ministry of Health and Welfare Notification No. 20 of 1982). The results are shown below

[0060]

[Table 1]

As is clear from the above results, the composite resin molded product for infants of the present invention is extremely safe.

[0062]

Example 2 An elastomer composition containing 65 parts by weight of a styrene / ethylene / propylene / styrene copolymer, 35 parts by weight of polypropylene, and 20 parts by weight of liquid paraffin as a plasticizer was prepared. Separately, a crystalline polypropylene resin was prepared. This elastomer composition is colored pink.

First, polypropylene resin was injection-molded into the first mold shown in FIG. 4 to form the center portion of the pacifier seat plate. Next, after cooling the first mold to cure the center part of the seat plate, the formed center part of the seat plate is released from the mold and another mold 35 (second mold) shown in FIG. ) Is mounted on the rod top, and then a female mold is attached as shown in FIG. 5, and a pink colored elastomer composition is injection-molded to the second mold, and then the second mold is injected. The mold was cooled to cure the molded product, and then the mold was removed to manufacture a pacifier seat plate as shown in FIGS.

When the joint between the polypropylene resin molded portion and the elastomer molded portion of this molded body was observed, it was found that they were integrated at the boundary surface and they could not be separated.

Regarding the molded article produced in this manner, as described above, the standard of food hygiene law, food, additives, etc. (Showa 34 Ministry of Health and Welfare Notification 370) Container or container made of polyethylene as a main component As a result of the material test and the elution test based on the packaging (Ministry of Health and Welfare Notification No. 20 of 1982), safety was confirmed as in Example 1.

[0066]

Example 3 An elastomer composition containing 90 parts by weight of a styrene / ethylene / propylene / styrene copolymer, 10 parts by weight of polypropylene, and 50 parts by weight of liquid paraffin as a plasticizer was prepared. Separately, a crystalline polypropylene resin (tone-colored) was prepared.

First, the elastomer composition was injection-molded in the mold shown in FIG. 8A to form the protrusions at the joints of the infant composite resin molding. Then, the mold was cooled to cure the protrusion, and then the male mold was removed while leaving the protrusion on the female mold.

As shown in FIG. 8B, another male mold for forming a gap for forming the molded body on the bottom of the protrusion thus formed is formed between the female mold and the male mold. A gap for forming a main body portion was formed by mounting on the left female mold. Then, a polypropylene resin colored yellow was injected into the gap formed by the mold, the mold was cooled to cure the molded product, and then the mold was removed to manufacture a composite resin molded product for infants.

When the joint between the polypropylene resin molded portion and the elastomer molded portion of this molded body was observed, it was found that they were integrated at the boundary surface and they could not be separated.

Regarding the molded article produced in this way, as described above, the standard of food hygiene law, foods, additives, etc. (Showa 34 Ministry of Health and Welfare Notification 370) Container or container made of polyethylene as a main component As a result of conducting a material test and a dissolution test based on packaging (Ministry of Health and Welfare Notification No. 20 of 1982), safety was confirmed as in Example 1.

[Brief description of drawings]

FIG. 1 is a view partially showing a cross section of a lid of a drink container which is an example of the composite resin molded product for infants of the present invention.

FIG. 2 is a perspective view showing a seat plate of a pacifier which is an example of the composite resin molded body for infants of the present invention.

FIG. 3 is a sectional view taken along line BB in FIG.

FIG. 4 is a view showing a mold for manufacturing the seat plate for the pacifier shown in FIGS. 2 and 3 in a cross section taken along the line AA in FIG.

FIG. 4 is a view showing a mold for manufacturing the seat plate for the pacifier shown in FIGS. 2 and 3 in a cross section taken along the line AA in FIG.

6 is a view showing a cross section of a mold for molding a packing part of a lid part of the drink container shown in FIG. 1.

FIG. 7 is a drawing showing a cross section of a mold for molding the outer peripheral portion of the lid of the drink container shown in FIG. 1.

[Fig. 8] Fig. 8 is a diagram showing another embodiment of a mold for producing the infant composite resin molded body of the present invention.

[Explanation of symbols]

 10 ... Molded part composed of elastomer composition 11 ... Molded part composed of polypropylene resin 12 ... Joining part 30 ... Mold 31 ... Molded part composed of polypropylene resin 32 ... Elastomer composition Molding part 35 ... Other mold 40A ... Male mold 40B ... Female mold 40C ... New female mold 41 ... Molding part made of polypropylene resin 42 ... Elastomer Molded part composed of composition 50A ... Male mold 50B ... Female mold 50C ... New female mold 51 ... Infant composite resin molded product 52 ... Projection (from elastomer composition Forming part)

[Procedure amendment]

[Submission date] March 7, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

The styrene / ethylene / propylene / styrene copolymer (S-EP-S) used in the present invention is a block copolymer composed of an ethylene unit and a propylene unit randomly bonded to a polymer of a styrene unit. . The styrene / ethylene / propylene / styrene copolymer (S-EP-S) is usually an elastomer produced by hydrogenating a styrene / isoprene / styrene copolymer (SIS). Furthermore, this styrene / ethylene / propylene / styrene copolymer (S-
EP-S) has excellent elastomer properties, is highly safe, and is inexpensive. This styrene
Ethylene / Propylene / Styrene Copolymer (S-EP-
As a substance similar in name to S), styrene / ethylene / butylene / styrene copolymer (S-EB-) which is a hydrogenated product of styrene / butylene / styrene copolymer (SBS)
S), but both are completely different substances, for example,
Both can be clearly distinguished by measuring the ¹³ C-NMR spectrum.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

Regarding the elastomer composition as described above
The hardness (HSA) measured by JIS-K-6301 is usually 20-1
In the range of 00, 100% modulus as measured in the same manner it is usually 0.01~ 2.00 kgf / mm ^2, the tensile strength is usually 0.50~5.00kgf / mm ^2, tensile elongation Usually 50
It is in the range of 0 to 1200%. Further, the compression set measured by JIS-K-6301 under the condition of 70 ° C. × 22 hours is
It is usually in the range of 20 to 100%. In addition, BS-
The impact resilience measured by 903 is usually 30-70%
Is within the range of.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

Molding part 11 made of polypropylene resin
May be a homopolymer of propylene or a copolymer of a monomer copolymerizable with propylene (for example, ethylene or butadiene). Further, this polypropylene resin can also be used as a mixture with other resins as long as the characteristics thereof are not impaired. For example, in the present invention, a small amount of resin such as polyethylene can be mixed with polypropylene resin for use. The polypropylene used here is a resin, not an elastomer (soft polymer), and the crystallinity of this polypropylene resin measured by an X-ray diffraction method is usually 10% or more, preferably 4 %.
5 % or more, and the melting point is usually 160 ° C. or more.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

The molding part 10 made of the elastomer composition and the molding part 11 made of polypropylene resin are the joint parts 12 of the two and are melted together without any other resin such as an adhesive. And are integrated. That is, microscopically, at the joint portion 12 between the two, it is considered that the elastomer composition and the polypropylene resin are integrated by forming a continuous layer at least at a part thereof. Therefore, the composite resin molded article for baby of the present invention is formed of the elastomer composition and the polypropylene resin, and does not substantially contain any other resin, and therefore, for example, the solvent of the adhesive, the unreacted monomer Such difficult-to-predict substances will not elute. Thus, the composite resin molded article for infants of the present invention is formed by forming a continuous layer of the two, for example, at the joint portion where the forming materials are different, or the surface is By closely adhering to each other, the respective molded parts are firmly joined. That is, styrene, ethylene, propylene,
Since the styrene copolymer has a propylene unit in its molecular structure, it has very good compatibility with the polypropylene resin, and joins the molded part 11 made of the polypropylene resin and the molded part 10 made of the elastomer composition. Excellent integration of both in the part 12 . And when this elastomer composition contains a polypropylene resin, its integration is further improved and the joining state of both is extremely good.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

First, the method B will be described. By the method B, a pacifier seat plate as shown in FIGS. 2 and 3, for example, can be manufactured. FIG. 5 shows this FIG.
FIG. 4 is a view showing a state at the time of manufacturing the composite resin molded product for infants (sitting plate of a pacifier) as illustrated in FIG. 3 and a cross section taken along the line AA in FIG. 2. In manufacturing a pacifier seat plate, first, a molding member 31 made of polypropylene resin is used by using a mold 30 having a cross section as shown in FIG. 4, for example.
To form. The molding member 31 made of this polypropylene resin corresponds to 11 in FIG. Next, the member 31 is released from the mold 30. The demolded molding member 31 is loaded into another mold 35 as shown in FIG.
Next, the other component, the elastomer composition, is melt-injected into the mold. The molded part formed by this elastomer composition corresponds to 10 in FIGS. 2 and 3. By injection molding in this manner, it is considered that a continuous layer composed of both components is formed at at least a part of the joint between the molded part made of the elastomer composition and the molded part made of polypropylene resin. The molding portion 32 (outer peripheral portion) made of the composition and the molding portion 31 made of polypropylene resin are integrated.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0055

[Correction method] Change

[Correction content]

(1) Styrene / ethylene / propylene / styrene copolymer Septon 4055 (manufactured by Kuraray Co., Ltd.) (2) Polypropylene MS670 (manufactured by Tokuyama Soda Co., Ltd.) (3) Liquid paraffin KP-100 (Idemitsu Kosan Co., Ltd.) (Made by)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location // B29K 9:00 23:00 (72) Inventor Manabu Kajiyama 3 Nihonbashihoncho, Chuo-ku, Tokyo 11-5, Riken Vinyl Industry Co., Ltd.

Claims (12)

[Claims] 1. A molded part formed of an elastomer composition containing liquid paraffin and containing styrene / ethylene / propylene / styrene copolymer as a main component.
A composite resin molded product for infants, characterized in that a molded part made of polypropylene resin is melt-integrated at a joint part between them. 2. The elastomer composition contains 51 to 99% by weight of styrene / ethylene / propylene / styrene copolymer and 1 to 49% by weight of polypropylene as elastomer components. The composite resin molded product for infants according to claim 1. 3. The composite resin molded product for infants according to claim 1, wherein the content of polypropylene in the elastomer composition is less than 1% by weight. 4. Liquid paraffin is added in an amount of 0.1 parts by weight to 100 parts by weight of the elastomer component in the elastomer composition.
It is contained in an amount of 150 parts by weight to 150 parts by weight, and the composite resin molded product for infants according to any one of claims 1 to 3. 5. A step of forming a molded part of the elastomer composition by melt-injecting an elastomer composition containing liquid paraffin and containing styrene / ethylene / propylene / styrene copolymer as a main component, and the elastomer composition. A polypropylene resin molded portion is formed by melt-injecting a polypropylene resin into a mold equipped with the molded article portion, and the elastomer composition and the polypropylene resin are fused and integrated at a joint portion between the two. A method for producing a composite resin molded product for infants, which is characterized by the above. 6. The elastomer composition contains 51 to 99% by weight of styrene / ethylene / propylene / styrene copolymer and 1 to 49% by weight of polypropylene as elastomer components. The method for producing the composite resin molded product for infants according to claim 5. 7. The method for producing a composite resin molded product for infants according to claim 5, wherein the content of polypropylene in the elastomer composition is less than 1% by weight. 8. Liquid paraffin is added in an amount of 0.1 with respect to 100 parts by weight of the elastomer component in the elastomer composition.
It is contained in an amount of 150 parts by weight to 150 parts by weight, and the method for producing a composite resin molded product for infants according to any one of claims 5 to 7. 9. A polypropylene resin molded part is formed by injection molding of polypropylene resin, and then liquid paraffin is contained in a mold in which the polypropylene resin molded part is mounted and styrene / ethylene / propylene / styrene copolymer weight is added. While forming an elastomer composition molded part by melt-injecting an elastomer composition mainly composed of coalescence,
A method for producing a composite resin molded product for infants, characterized in that the elastomer composition and the polypropylene resin are fusion-bonded and integrated at a joint portion between them. 10. The elastomer composition contains 51 to 99% by weight of styrene / ethylene / propylene / styrene copolymer and 1 to 49% by weight of polypropylene as elastomer components. The method for producing a composite resin molded body for infants according to claim 9. 11. The method for producing a composite resin molded product for infants according to claim 9, wherein the content of polypropylene in the elastomer composition is less than 1% by weight. 12. Liquid paraffin is added to 100 parts by weight of the elastomer component in the elastomer composition.
The method for producing a composite resin molded product for infants according to any one of claims 9 to 11, characterized in that it is contained in an amount of 1 to 150 parts by weight.