JP7082611B2 - Manufacturing method of polypropylene-based resin foamed particles, polypropylene-based resin foamed particles and polypropylene-based resin in-mold foam molded product - Google Patents

Description

The present invention relates to a method for producing polypropylene-based resin foamed particles, polypropylene-based resin foamed particles, and a polypropylene-based resin in-mold foamed molded product.

The polypropylene-based resin in-mold foam molded body made of polypropylene-based resin foam particles is used in various fields such as packaging materials, cushioning materials, heat insulating materials, and building materials because it has excellent physical properties such as cushioning and heat insulating properties. .. In particular, according to the in-mold foam molding method for polypropylene-based resin, a polypropylene-based resin foamed particle is filled in a mold and then heated with steam or the like to fuse the foamed particles to each other to obtain a foam having a predetermined shape. Products of various shapes can be obtained relatively easily. Therefore, the polypropylene-based resin in-mold foam molding method is used for producing a polypropylene-based resin in-mold foam molded article that can be used for many purposes.

The polypropylene-based resin foamed particles can be obtained by foaming the polypropylene-based resin particles by the following method: (i) Mainly polypropylene-based resin particles, water as a dispersion medium, a physical foaming agent, a dispersant, and a dispersion aid. (Ii) Disperse the contained mixture (dispersion liquid) by stirring, and raise and increase the temperature inside the pressure-resistant container; (iii) Pressure lower than the internal pressure of the pressure-resistant container. Disperse the dispersion in the pressure-resistant container to the area. The dispersant is used to prevent agglomeration of resin particles in the pressure-resistant container or foamed particles immediately after being discharged to the outside of the pressure-resistant container.

Conventionally, various manufacturing methods have been developed as a manufacturing method for polypropylene-based resin foamed particles. For example, Patent Documents 1 to 3 disclose a production method using tricalcium phosphate as a dispersant. Patent Document 4 discloses a production method using a mineral such as silicate as a dispersant. Patent Document 5 discloses a production method using a silicate as a dispersant and an acidic substance (pH adjuster) as a dispersion enhancer.

On the other hand, as a buffer packaging material for electronic parts such as OA equipment and mechanical parts, a polypropylene-based resin in-mold foam molded product having a high foaming ratio is preferably used in order to enhance the transportation effect.

WO2013 / 137344A WO2013 / 137411 Gazette WO2013 / 011951 Japanese Unexamined Patent Publication No. 6-20071 JP 2001-164024

However, the above-mentioned prior art is not sufficient from the viewpoint of efficiently obtaining polypropylene-based resin foamed particles that can provide a polypropylene-based resin in-mold foam molded product having excellent quality, and further improvement is made. There was room for.

One embodiment of the present invention has been made in view of the above problems, and an object thereof is to efficiently obtain polypropylene-based resin foam particles capable of providing a polypropylene-based resin in-mold foam molded product having excellent quality. It is to provide a novel method for producing polypropylene-based resin foamed particles.

As a result of diligent research in view of the above-mentioned problems, the present inventor has produced polypropylene-based resin foam particles that solve the above-mentioned problems by containing an aliphatic diethanolamine fatty acid ester and / or an aliphatic diethanolamine in a specific amount of a polypropylene-based resin. We found a way to do this and came up with the present invention.

That is, the method for producing polypropylene-based resin foam particles according to an embodiment of the present invention is a polypropylene-based method using a dispersion liquid containing polypropylene-based resin particles, water, and silicate, and an inorganic foaming agent containing carbon dioxide. A method for producing resin foamed particles, wherein (A) the polypropylene-based resin particles are made of a polypropylene-based resin composition, and (B) the polypropylene-based resin composition is composed of an aliphatic diethanolamine fatty acid ester and / or an aliphatic diethanolamine. In total, the polypropylene-based resin contains 0.2 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight. The resin particles are contained in an amount of 25 parts by weight or more and 100 parts by weight or less, (b) the silicate is contained in an amount of 0.05 parts by weight or more and 0.25 parts by weight or less, and (D) the pH of the dispersion is 5 or more and 9 or less. This is a method for producing a polypropylene-based resin foamed particle, which is characterized by the above.

According to one embodiment of the present invention, there is provided a method for producing polypropylene-based resin foamed particles, which can efficiently obtain polypropylene-based resin foamed particles that can provide a polypropylene-based resin-molded in-foamed molded article having excellent quality. can do.

Differential scanning calorimetry in which the polypropylene-based resin foamed particles obtained by the method for producing polypropylene-based resin foamed particles according to the embodiment of the present invention are heated from 40 ° C. to 220 ° C. at a heating rate of 10 ° C./min. It is an example of the DSC curve obtained by performing (DSC). The horizontal axis is temperature and the vertical axis is heat absorption. The portion surrounded by the broken line of the heat of fusion peak on the low temperature side and the line segment AB is Ql, and the portion of the heat of melting peak on the high temperature side and the portion surrounded by the broken line of the line segment AC is Qh. It is a perspective view which shows the schematic structure of the foamed molded article 1 in a polypropylene resin mold which concerns on another Embodiment of this invention. It is a top view which looked at the polypropylene-based resin mold in-foam molded article 1 which concerns on another Embodiment of this invention from the x direction.

An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications can be made within the scope of the claims. The technical scope of the present invention also includes embodiments or examples obtained by appropriately combining the technical means disclosed in different embodiments or examples. Further, by combining the technical means disclosed in each embodiment, new technical features can be formed. In addition, all the academic documents and patent documents described in the present specification are incorporated as references in the present specification. Further, unless otherwise specified in the present specification, "A to B" representing a numerical range is intended to be "A or more (including A and larger than A) and B or less (including B and smaller than B)".

[Technical Idea of One Embodiment of the Present Invention]
As a result of diligent studies by the present inventor, it has been found that the techniques described in the above-mentioned prior art documents 1 to 5 have room for improvement or problems as shown below.

Prior Art Documents 1 to 3 disclose techniques for producing polypropylene-based resin foam particles or polyethylene-based resin foam particles, and in the production method, tertiary calcium phosphate is used as a dispersant. In the techniques described in the prior art documents 1 to 3, the dispersibility of the polypropylene-based resin or the polyethylene-based resin is high due to the use of tricalcium phosphate. However, when the present inventor performs in-mold foam molding using the foamed particles obtained by using the tricalcium phosphate, the tricalcium phosphate adhering to the surface of the foamed particles is desorbed from the foamed particles. I noticed that it deposits on the mold (in other words, it contaminates the mold). Therefore, the techniques described in the prior art documents 1 to 3 have room for further improvement in terms of suppressing the accumulation of the dispersant in the mold.

Minerals such as silicate are known as dispersants that are difficult to desorb from the surface of the foamed particles, and among the silicates, kaolin is preferably used. For example, the technique described in Prior Art Document 4 is a technique relating to a method for producing polyolefin-based resin foamed particles, and a silicate is used as a dispersant. However, when the silicate is used as a dispersant, the present inventor needs to add a large amount of the silicate to water as a dispersion medium in order to prevent agglomeration of resin particles in the pressure resistant container. I noticed that there is. Furthermore, when the present inventor performs in-mold foam molding using polypropylene-based resin foamed particles obtained by using a large amount of silicate, (a) silicic acid is applied to the mold during in-mold foam molding. It has been found that (b) a polypropylene-based resin in-mold foam molded product in which the polypropylene-based resin foamed particles are not sufficiently fused to each other may be obtained, although the salt does not accumulate. Therefore, the technique described in Prior Art Document 4 has a problem that the fusion of polypropylene-based resin foam particles in in-mold foam molding is insufficient.

An acidic substance (pH adjuster) that adjusts the zeta potential of the silicate to the positive electrode in order to reduce the amount of the dispersant silicate added, in other words, to efficiently attach the dispersant to the foamed particles. ) Can be further added as a dispersion strengthening agent to water as a dispersion medium. For example, the technique described in Prior Art Document 5 is a technique relating to a method for producing polypropylene-based resin foamed particles, in which a silicate is used as a dispersant and an acidic substance (pH adjuster) is used as a dispersion strengthening agent. There is. However, the present inventor has found that the technique described in Prior Art Document 5 uses an acidic substance, which causes corrosion of the pressure resistant container and surrounding equipment. Therefore, the technique described in Prior Art Document 5 has a problem that the pressure-resistant container and surrounding equipment are corroded.

Further, the polypropylene-based resin mold in-foamed molded product tends to be easily deformed immediately after molding (immediately after production) as the foaming ratio increases. In order to recover the deformed shape immediately after molding of the polypropylene-based resin mold in-foam molded product, a drying time depending on the degree of deformation is required. Therefore, the conventional foamed molded product in a polypropylene resin mold having a high foaming ratio has a problem that it needs to be dried for a long time due to deformation immediately after molding. The polypropylene-based resin mold in-foamed molded product having a high foaming ratio is intended to be a polypropylene-based resin in-mold foam molded product having a foaming ratio of 27 times or more (in other words, an apparent density of 33 g / L or less).

Further, the polypropylene-based resin in-mold foam molded product having a high foaming ratio can be produced by using polypropylene-based resin foamed particles having a high foaming ratio. The polypropylene-based resin foamed particles having a high foaming ratio are intended as polypropylene-based resin foamed particles having a foaming ratio of 18 times or more (in other words, an apparent density of 29 g / L or less).

As described above, the prior art is not sufficient from the viewpoint of efficiently obtaining polypropylene-based resin foam particles that can provide a polypropylene-based resin in-mold foam molded product having excellent quality.

The present inventors have completed the present invention in order to solve such a problem. The present invention efficiently, specifically, (a) prevents contamination of the mold, (b) prevents agglomeration of polypropylene-based resin particles and polypropylene-based resin foamed particles, and (c) corrodes equipment. It is an object of the present invention to produce polypropylene-based resin foamed particles having excellent quality and specifically satisfying the following (d) and (e): (d) Polypropylene having good fusing property. To provide a foamed molded product in a based resin mold; (e) Provided is a foamed molded product in a polypropylene resin mold in which deformation immediately after molding is suppressed even at a high foaming ratio, thereby shortening the drying time. thing.

An embodiment of the present invention will be described below.

[1. Manufacturing method of polypropylene-based resin foam particles]
The method for producing polypropylene-based resin foamed particles according to an embodiment of the present invention is a polypropylene-based resin foaming using a dispersion liquid containing polypropylene-based resin particles, water, and silicate, and an inorganic foaming agent containing carbon dioxide. A method for producing particles, wherein (A) the polypropylene-based resin particles are composed of a polypropylene-based resin composition, and (B) the polypropylene-based resin composition is a total of aliphatic diethanolamine fatty acid ester and / or aliphatic diethanolamine. With respect to 100 parts by weight of the polypropylene-based resin, 0.2 parts by weight or more and 5 parts by weight or less are contained. (C) The dispersion liquid contains 100 parts by weight of water and (a) the polypropylene-based resin particles. 25 parts by weight or more and 100 parts by weight or less, (b) 0.05 parts by weight or more and 0.25 parts by weight or less of the silicate, and (D) the pH of the dispersion is 5 or more and 9 or less. It is characterized by. Here, the dispersion liquids described in (C) and (D) above are intended to be dispersion liquids that do not contain an inorganic foaming agent.

In the present specification, "a method for producing polypropylene-based resin foamed particles according to an embodiment of the present invention" is also simply referred to as "the present production method".

According to this production method, polypropylene-based resin foamed particles that can provide a polypropylene-based resin in-mold foamed molded product having excellent quality can be efficiently obtained. Specifically, (a) the mold is prevented from being contaminated, (b) the polypropylene-based resin particles and the polypropylene-based resin foamed particles are prevented from agglomerating, and (c) the equipment is not corroded. It is possible to obtain polypropylene-based resin foamed particles that can satisfy d) and (e): (d) to provide a polypropylene-based resin in-mold foam molded product having good meltability; (e) a high foaming ratio. Provided is a polypropylene-based resin in-mold foam molded product, which suppresses deformation immediately after molding and thereby shortens the drying time.

Further, according to the present manufacturing method, since it has the above-mentioned configuration, (a) it is possible to stabilize the dispersion system using the silicate even when the pH is set to a specific pH range in which corrosion of the equipment does not easily proceed. Therefore, it is possible to obtain polypropylene-based resin foam particles capable of providing (b) a polypropylene-based resin in-mold foam molded product in which deformation immediately after molding is suppressed even at a high foaming ratio.

(1-1. Material)
(1-1-1. Polypropylene resin composition)
In the present production method, the polypropylene-based resin particles are made of a polypropylene-based resin composition. The polypropylene-based resin composition contains a polypropylene-based resin, an aliphatic diethanolamine fatty acid ester and / or an aliphatic diethanolamine, and other additives.

(1-1-1-1. Polypropylene resin)
The polypropylene-based resin used in one embodiment of the present invention is not particularly limited, and is not particularly limited, and is a polypropylene homopolymer, an ethylene / propylene random copolymer, a butene-1 / propylene random copolymer, or an ethylene / butene-1 / propylene random. Examples thereof include copolymers, ethylene / propylene block copolymers, butene-1 / propylene block copolymers, propylene-chlorinated vinyl copolymers, propylene / maleic anhydride copolymers and the like. Among these, the ethylene / propylene random copolymer and the ethylene / butene-1 / propylene random copolymer have good foamability of the polypropylene-based resin foamed particles, and the polypropylene-based resin in-mold foamed molded product. Is suitable because it has good moldability. The butene-1 is synonymous with 1-butene.

In addition, [1. [Method for producing polypropylene-based resin foamed particles], unless otherwise specified, (a) "polypropylene-based resin foamed particles" is based on the method for producing polypropylene-based resin foamed particles according to an embodiment of the present invention. In-mold foam molding using polypropylene-based resin foam particles according to one embodiment of the present invention is intended for (b) "polypropylene-based resin foam-molded body", which is intended for polypropylene-based resin foam particles obtained by production. It is intended to be a polypropylene-based resin in-mold foam molded body obtained by being manufactured by.

In this production method, consider the case where an ethylene / propylene random copolymer or an ethylene / butene-1 / propylene random copolymer is used as the polypropylene-based resin (case A). In Case A, the ethylene content in the ethylene / propylene random copolymer or the ethylene / butene-1 / propylene random copolymer is 0.2% by weight or more and 10% by weight or less in 100% by weight of each copolymer. preferable. Further, in Case A, the butene content in the ethylene / butene-1 / propylene random copolymer is preferably 0.2% by weight or more and 10% by weight or less in 100% by weight of the copolymer. Further, in Case A, the total content of ethylene and butene-1 in the ethylene / propylene random copolymer or the ethylene / butene-1 / propylene random copolymer is 0. It is preferably 5% by weight or more and 10% by weight or less. In case A, when the content of ethylene or butene-1 in the ethylene / propylene random copolymer or the ethylene / butene-1 / propylene random copolymer is (a) less than 0.2% by weight, polypropylene. The foamability and / or moldability of the foamed resin particles tends to decrease, and when (b) exceeds 10% by weight, the mechanical properties of the foamed molded product in the polypropylene resin mold tend to decrease.

The melting point of the polypropylene-based resin used in one embodiment of the present invention is not particularly limited, and is, for example, preferably 125 ° C. or higher and 160 ° C. or lower, and more preferably 130 ° C. or higher and 155 ° C. or lower. When the melting point of the polypropylene-based resin is (a) less than 125 ° C., the heat resistance of the foamed molded product in the polypropylene-based resin mold tends to decrease, and when (n) exceeds 160 ° C., the polypropylene-based resin is used in this production method. It tends to be difficult to increase the expansion ratio of the resin foam particles.

Here, the melting point of the polypropylene-based resin is measured by the differential scanning calorimetry method (hereinafter referred to as “DSC method”). The specific operation procedure is as follows: (1) After heating 5 to 6 mg of polypropylene resin from 40 ° C. to 220 ° C. at a heating rate of 10 ° C./min and melting it; (2) 10 After the temperature is lowered from 220 ° C. to 40 ° C. at a temperature lowering rate of ° C./min to crystallize; (3) the temperature is further raised from 40 ° C. to 220 ° C. at a heating rate of 10 ° C./min. The temperature of the peak (melting peak) of the DSC curve obtained at the time of the second temperature rise (that is, at the time of (3)) can be obtained as the melting point.

The amount of heat of crystal melting of the polypropylene resin used in one embodiment of the present invention is not particularly limited, and is preferably 50 J / g or more and 110 J / g or less, and more preferably 75 J / g or more and 100 J / g or less. When the heat of crystal melting of the polypropylene-based resin is (a) less than 50 J / g, it becomes difficult to maintain the shape of the polypropylene-based resin foamed particles in the in-mold foam molding using the polypropylene-based resin foamed particles, and (b) 110J. If it exceeds / g, it becomes difficult to increase the foaming ratio.

Here, the amount of heat of crystal melting of the polypropylene-based resin is measured by the same DSC method as the above-mentioned measurement of the melting point of the polypropylene-based resin. Specifically, the following method is performed by performing the above-mentioned operations (1) to (3) and using the peak (melting peak) of the DSC curve obtained at the time of the second temperature rise (that is, at the time of (3)). Can be obtained by. When a tangent line is drawn from the intersection of the line from the melting peak toward the high temperature side and the baseline on the high temperature side toward the low temperature side differential curve, the amount of heat surrounded by the tangent line and the melting peak is calculated as the amount of heat of crystal melting. be able to.

The melt index (hereinafter referred to as “MI”) of the polypropylene-based resin used in one embodiment of the present invention is not particularly limited, and is preferably 3 g / 10 minutes or more and 30 g / 10 minutes or less, and 4 g / 10 minutes or more and 20 g. / 10 minutes or less is more preferable, and 5 g / 10 minutes or more and 18 g / 10 minutes or less is further preferable.

When the MI of the polypropylene-based resin is less than 3 g / 10 minutes, it tends to be difficult to increase the foaming ratio. When the MI of the polypropylene-based resin exceeds 30 g / 10 minutes, bubbles of the polypropylene-based resin foamed particles communicate with each other. As a result, there is a tendency that (a) the compressive strength of the polypropylene-based resin mold in-foam molded product is lowered, or (b) the surface property of the polypropylene-based resin mold in-foamed molded product is lowered.

Consider the case where the MI of the polypropylene resin is in the range of 3 g / 10 minutes or more and 30 g / 10 minutes or less. In this case, polypropylene-based resin foamed particles having a relatively large foaming ratio can be easily obtained. Further, in this case, the polypropylene-based resin mold in-foamed molded product has the advantages of excellent surface beauty and a small dimensional shrinkage.

Here, the MI value uses the MI measuring instrument described in JIS K7210: 1999, the orifice diameter is 2.0959 ± 0.005 mmφ, the orifice length is 8.000 ± 0.025 mm, and the load is 2160 g. , 230 ± 0.2 ° C., and is a value measured under the condition.

The polymerization catalyst for synthesizing the polypropylene-based resin used in one embodiment of the present invention is not particularly limited, and a Ziegler-based catalyst, a metallocene-based catalyst, or the like can be used.

(1-1-1-2. Aliphatic diethanolamine fatty acid ester and aliphatic diethanolamine)
The total content of the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine in the polypropylene-based resin composition used in one embodiment of the present invention is 0.2 parts by weight or more with respect to 100 parts by weight of the polypropylene-based resin. It is more preferably 0.3 parts by weight or more and 3 parts by weight or less, and further preferably 0.5 parts by weight or more and 1.5 parts by weight or less.

Consider the case where the total content of the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine is less than 0.2 parts by weight with respect to 100 parts by weight of the polypropylene-based resin. In this case, (a) in the present production method, when the pH of the dispersion liquid contained in the pressure-resistant container is 5 or more and 9 or less, the dispersion of polypropylene-based resin particles in the dispersion liquid tends to be unstable. In addition, (b) the suppression of deformation of the polypropylene-based resin in-mold foam molded product immediately after molding is insufficient. Here, the pH of the dispersion liquid being 5 or more and 9 or less is one configuration in the present production method. Consider a case where the total content of the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine exceeds 5 parts by weight with respect to 100 parts by weight of the polypropylene-based resin. In this case, (a) stickiness due to the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine may occur on the surface of the polypropylene-based resin foamed particles and / or the polypropylene-based resin in-mold foam molded product, and (a) b) When polypropylene-based resin particles are produced using an extruder, the amount of the melt-kneaded material containing the polypropylene-based resin composition discharged from the extruder is not stable. The shape and / or weight of a single grain tends to vary.

In one embodiment of the invention, as long as the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine is used, the weight ratio of the aliphatic diethanolamine fatty acid ester to the total weight of the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine is particularly limited. There is no. In other words, the aliphatic diethanolamine fatty acid ester or the aliphatic diethanolamine can be used alone by containing them in the polypropylene-based resin.

In one embodiment of the present invention, the polypropylene-based resin composition contains an aliphatic diethanolamine fatty acid ester and an aliphatic diethanolamine in a total amount of 0.2 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the polypropylene-based resin. Is preferable. According to the above configuration, it is possible to suppress the deformation of the polypropylene-based resin in-mold foam molded product immediately after molding.

The aliphatic diethanolamine fatty acid ester used in one embodiment of the present invention is not particularly limited, but is preferably a compound represented by the general formula (1). According to the above configuration, (a) polypropylene-based resin foamed particles and / or the surface of the polypropylene-based resin in-mold foamed molded product does not have stickiness due to the aliphatic diethanolamine fatty acid ester, and (b) polypropylene-based resin. It has the advantage of not accelerating the deterioration of the resin.

（Ｒ^１は、炭素数１２～２４のアルキル基、Ｒ^２は炭素数１１～２３のアルキル基を示し、Ｒ^１とＲ^２は同じでもよく、異なっていてもよい）
ここで、脂肪族ジエタノールアミン脂肪酸エステルは、所定のＲ^１およびＲ^２を有する単一の化合物のみで構成されていてもよいし、Ｒ^１およびＲ^２のうち、少なくとも一方の炭素数が異なる複数の化合物を含んだ混合物であってもよい。

(R ¹ represents an alkyl group having 12 to 24 carbon atoms, R ² represents an alkyl group having 11 to 23 carbon atoms, and R ¹ and R ² may be the same or different).
Here, the aliphatic diethanolamine fatty acid ester may be composed of only a single compound having predetermined R ¹ and R ² , or a plurality of R ¹ and R ² having different carbon atoms at least one of them. It may be a mixture containing a compound.

Specific examples of the aliphatic diethanolamine fatty acid ester in one embodiment of the present invention include lauryl diethanolamine monolauric acid ester, lauryl diethanolamine monomyristin acid ester, lauryl diethanolamine monopentadecylate ester, lauryl diethanolamine monopalmitic acid ester, and lauryl diethanolamine. Monomargaric acid ester, lauryl diethanolamine monostearic acid ester, lauryl diethanolamine monoarachidic acid ester, lauryl diethanolamine monobechenic acid ester, lauryl diethanolamine monolignoseric acid ester; myristyl diethanolamine monolauric acid ester, myristyl diethanolamine monomyristic acid ester, myristyl Diethanolamine monopentadecylate ester, myristyldiethanolamine monopalmitic acid ester, myristyldiethanolamine monomargaric acid ester, myristyldiethanolamine monostearic acid ester, myristyldiethanolamine monoarachidic acid ester, myristyldiethanolamine monobechenic acid ester, myristyldiethanolamine monolignoseric acid Esters, pentadecyldiethanolamine monolauric acid esters, pentadecyldiethanolamine monomyristic acid esters, pentadecyldiethanolamine monopentadecylic acid esters, pentadecyldiethanolamine monopalmitic acid esters, pentadecyldiethanolamine monomargaric acid esters, pentadecyldiethanolamine monostearic acid esters , Pentadecyldiethanolamine monoarachidic acid ester, pentadecyldiethanolamine monobechenic acid ester, pentadecyldiethanolamine monolignoseric acid ester; palmityl diethanolamine monolauric acid ester, palmityl diethanolamine monomyristic acid ester, palmityl diethanolamine monopentadecylate ester. , Palmityl diethanolamine monopalmitic acid ester, palmityl diethanolamine monomargaric acid ester, palmityl diethanolamine monostearic acid ester, palmityl diethanolamine monoarachidic acid ester, palmityl diethanolamine monobechenic acid ester, palmityl diethanolamine monolith Gnoceric acid ester; Margaryl diethanolamine monolauric acid ester, Margaryl diethanolamine monomyristic acid ester, Margaryl diethanolamine monopentadecylate ester, Margaryl diethanolamine monopalmitic acid ester, Margaryl diethanolamine monomargaric acid ester, Margaryl diethanolamine monosteare. Acid ester, Margaryl diethanolamine monoarachidic acid ester, Margaryl diethanolamine monobechenic acid ester, Margaryl diethanolamine monolignoseric acid ester; Stearyl diethanolamine monolauric acid ester, Stearyl diethanolamine monomyristic acid ester, Stearyl diethanolamine monopentadecylate, Stearyl Diethanolamine Monopalmitic Acid Ester, Stearyl Diethanolamine Monomargaric Acid Ester, Stearyl Diethanolamine Monostearic Acid Ester, Stearyl Diethanolamine Monoarachidic Acid Ester, Stearyl Diethanolamine Monobechenic Acid Ester, Stearyl Diethanolamine Monolignoseric Acid Ester; Arakizil Diethanolamine Monolauric Acid. Ester, arachidyl diethanolamine monomyristic acid ester, arachidyl diethanolamine monopentadecylate ester, arachidyl diethanolamine monopalmitic acid ester, arachidyl diethanolamine monomargaric acid ester, arachidyl diethanolamine monostearic acid ester, arachidyl diethanolamine monoarakidin Acid ester, arachidyl diethanolamine monobechenic acid ester, arachidyl diethanolamine monolignoseric acid ester; behenyl diethanolamine monolauric acid ester, behenyl diethanolamine monomyristic acid ester, behenyl diethanolamine monopentadecylate ester, behenyl diethanolamine monopalmitic acid ester, behenyl diethanolamine Monomargaric acid ester, behenyl diethanolamine monostearic acid ester, behenyl diethanolamine monoarachidic acid ester, behenyl diethanolamine monobechenic acid ester, behenyl diethanolamine monolignoseric acid ester; lignoceryl diethanolamine monolauric acid ester, ligno Ceryl diethanolamine monomyristic acid ester, lignoceryl diethanolamine monopentadecylate ester, lignoceryl diethanolamine monopalmitic acid ester, lignoceryl diethanolamine monomargaric acid ester, lignoceryl diethanolamine monostearic acid ester, lignoceryl diethanolamine monoaraxic acid ester, Examples thereof include lignoceryl diethanolamine monobechenic acid ester, lignoceryl diethanolamine monolignoseric acid ester, and the like. These may be used alone or in combination of two or more.

Among these aliphatic diethanolamine fatty acid esters, stearyldiethanolamine monostearic acid ester is more preferable because of its good compatibility with polypropylene-based resin. The stearyldiethanolamine monostearic acid ester is a compound represented by the general formula (1), in which R ¹ is − (CH ₂ ) ₁₇ CH ₃ and R ² is − (CH ₂ ) ₁₆ CH ₃ .

The aliphatic diethanolamine used in one embodiment of the present invention is not particularly limited, but is preferably a compound represented by the general formula (2). According to the above configuration, (a) no stickiness due to aliphatic diethanolamine occurs on the surface of the polypropylene-based resin foamed particles and / or the polypropylene-based resin in-mold foamed molded product, and (b) deterioration of the polypropylene-based resin. Has the advantage of not promoting.

（Ｒ^３は、炭素数１２～２４のアルキル基を示す）
ここで、脂肪族ジエタノールアミンは、所定のＲ^３を有する単一の化合物のみで構成されていてもよいし、Ｒ^３の炭素数が異なる複数の化合物を含んだ混合物であってもよい。

(R ³ indicates an alkyl group having 12 to 24 carbon atoms)
Here ^, the aliphatic diethanolamine may be composed of only a single compound having a predetermined R3 ^, or may be a mixture containing a plurality of compounds having different carbon atoms of R3.

Specific examples of the aliphatic diethanolamine in the embodiment of the present invention include lauryldiethanolamine, myristyldiethanolamine, pentadecyldiethanolamine, palmityldiethanolamine, margaryldiethanolamine, stearyldiethanolamine, arachidyldiethanolamine, behenyldiethanolamine, and lignoceryldiethanolamine. And so on. These may be used alone or in combination of two or more.

Among these aliphatic diethanolamines, stearyldiethanolamine is more preferable because it has good compatibility with polypropylene-based resins and a synergistic effect with stearyldiethanolamine monostearic acid ester can be easily obtained. Stearyldiethanolamine is a compound represented by the general formula (2) and in which R ³ is − (CH ₂ ) ₁₇ CH ₃ .

In one embodiment of the present invention, consider the case where the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine are used together (referred to as case B). In Case B, there is no particular limitation on the combination of each type of the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine. In Case B, the combination of the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine is preferably a combination of compounds represented by the general formula (1) and the general formula (2). According to the above configuration, (a) no stickiness due to the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine is generated on the surface of the polypropylene-based resin foamed particles and / or the polypropylene-based resin in-mold foamed molded product, and (b). ) It has the advantage of not accelerating the deterioration of the polypropylene resin used. In Case B, as a combination of the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine, stearyldiethanolamine monostearic acid ester (R ¹ =-(CH ₂ ) ₁₇ CH ₃ , R ² =-(CH ₂ ) ₁₆ CH ₃ ) And stearyldiethanolamine (R ³ =-(CH ₂ ) ₁₇ CH ₃ ) are more preferred. According to the above configuration, there are advantages that (a) compatibility with a polypropylene resin is good, and (b) a synergistic effect can be easily obtained by the combined use of an aliphatic diethanolamine fatty acid ester and an aliphatic diethanolamine.

In one embodiment of the present invention, the method for mixing the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine with the polypropylene-based resin is not particularly limited. For example, it is also possible to prepare a master batch of an aliphatic diethanolamine fatty acid ester and / or an aliphatic diethanolamine in advance and mix the master batch with a polypropylene-based resin. The master batch of aliphatic diethanolamine fatty acid ester and / or aliphatic diethanolamine contains aliphatic diethanolamine fatty acid ester and / or aliphatic diethanolamine as the same resin as or different from the polypropylene resin which is the main component of the polypropylene resin composition. It can be produced by mixing with.

Consider the case where the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine are used together. In this case, the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine may be mixed in advance before the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine are mixed with the polypropylene-based resin.

(1-1-1-3. Other additives)
In the polypropylene-based resin composition according to the embodiment of the present invention, various additives can be added as long as the effects of the present invention are not impaired. Examples of such additives include organic pigments, antioxidants, light resistance improvers, bubble nucleating agents, flame retardants, water-absorbing compounds, antistatic agents and the like.

Examples of the organic pigment include, but are not limited to, organic pigments such as perylene-based, polyazo-based, and quinacridone-based.

The content of the organic pigment is 0.001 part by weight or more and 0.1 part by weight or less with respect to 100 parts by weight of the polypropylene resin, that is, the dispersibility of the polypropylene resin particles (in other words, the polypropylene resin). It is preferable from the viewpoint of uniformity of coloring with respect to particles). When the content of the organic pigment exceeds 0.1 part by weight with respect to 100 parts by weight of the polypropylene-based resin, the bubble diameter of the polypropylene-based resin foamed particles may be fine. As a result, the surface properties of the polypropylene-based resin mold in-foam molded product are inferior, and the polypropylene-based resin mold in-foam foam molded product tends to have a poor appearance.

In one embodiment of the present invention, the method of mixing the organic pigment with the polypropylene-based resin is not particularly limited. For example, a masterbatch of an organic pigment is prepared in advance by mixing an organic pigment with a resin that is exactly the same as or different from the polypropylene resin that is the main component of the polypropylene resin composition, and the masterbatch is used as a polypropylene resin. It is also possible to mix.

Examples of the antioxidant include, but are not limited to, phenolic antioxidants, phosphorus-based antioxidants and the like.

Examples of the light resistance improving agent include, but are not limited to, hindered amine-based light resistance improving agents.

Examples of the bubble nucleating agent include, but are not limited to, talc, kaolin, barium sulfate, zinc borate, silicon dioxide and the like.

Examples of the flame retardant include, but are not limited to, halogen-based flame retardants, phosphorus-based flame retardants, hindered amine-based flame retardants, and the like.

Examples of the water-absorbent compound include substances that can absorb water and allow water to act as a foaming agent by releasing the absorbed water when foaming polypropylene-based resin particles. Specific examples of the water-absorbent compound include, but are not limited to, polyethylene glycol, glycerin, and melamine. Among these water-absorbent compounds, polyethylene glycol is more preferable, and polyethylene glycol having an average molecular weight of 200 or more and 6000 or less is most preferable.

Examples of the antistatic agent include the above-mentioned aliphatic diethanolamine fatty acid ester and aliphatic diethanolamine, which are one constitution of the present production method, and other substances such as hydroxyalkylethanolamine and glycerin fatty acid ester. Examples of the surfactant. Further, for the purpose of improving the antistatic performance, the aliphatic alcohol may be contained in an amount of 0.001 part by weight or more and 2 parts by weight or less with respect to 100 parts by weight of the polypropylene resin.

Such an aliphatic alcohol is not particularly limited, but a compound represented by the general formula (3) is preferably used.

（Ｒ^４は、炭素数１２～２４のアルキル基を示す）
ここで、脂肪族アルコールは、所定のＲ^４を有する単一の化合物のみで構成されていてもよいし、Ｒ^４の炭素数が異なる複数の化合物を含んだ混合物であってもよい。

( ^R4 indicates an alkyl group having 12 to 24 carbon atoms)
Here, the aliphatic alcohol may be composed of only a single compound having a predetermined ^R4 , or may be a mixture containing a plurality of compounds having different carbon atoms of ^R4 .

Electro stripper TS-15B (manufactured by Kao Co., Ltd.) is used as an antistatic agent as a mixture of an aliphatic diethanolamine fatty acid ester and an aliphatic diethanolamine that can be used in one embodiment of the present invention, to which an aliphatic alcohol is further added. It is commercially available. The electrostripper TS-15B is specifically a mixture of stearyldiethanolamine monostearic acid ester, stearyldiethanolamine and a fatty alcohol. The electrostripper TS-15B can be used by adjusting the amounts of the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine within the range of the present production method.

(1-1-2. Polypropylene resin particles)
The polypropylene-based resin composition according to the embodiment of the present invention is usually preferably molded into a particle shape in advance so that it can be easily used in the foaming step to obtain polypropylene-based resin particles. As a method for producing the polypropylene-based resin particles, (i) a polypropylene-based resin composition is melt-kneaded using an extruder, a kneader, a bambali mixer, a roll, or the like to prepare a melt-kneaded product, and then (ii) the melting is performed. Examples thereof include a method of obtaining polypropylene-based resin particles by molding the kneaded material into a desired shape such as a columnar shape, an elliptical shape, a spherical shape, a cubic shape, a rectangular shape, a tubular shape (straw shape), and the like.

The shape of the polypropylene-based resin particles is not always the same as the shape of the polypropylene-based resin foamed particles. For example, polypropylene-based resin particles may shrink in a foaming step such as a one-step foaming step and a two-step foaming step described later. In such a case, spherical polypropylene-based resin foam particles may be obtained from the columnar or elliptical polypropylene-based resin particles.

Among the methods for producing polypropylene-based resin particles, from the viewpoint of productivity, (i) the polypropylene-based resin composition is melt-kneaded with an extruder to prepare a melt-kneaded product, and then (ii) the melt-kneaded product is extruded. A method of extruding into a strand shape from the tip of the machine and then cutting the extruded melt-kneaded product to obtain polypropylene-based resin particles is more preferable.

In addition, the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine, and other additives are usually added to the polypropylene resin before or melted in the process of (i) manufacturing the polypropylene resin particles to form a mixture. (Ii) It is preferable to mix the mixture with a polypropylene resin by melt-kneading the mixture with an extruder to produce a melt-kneaded product. By doing so, the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine, and other additives can be uniformly dispersed in the polypropylene-based resin particles.

In one embodiment of the present invention, the average particle size of the polypropylene-based resin particles is preferably 0.1 mm or more and 10 mm or less, and more preferably 0.5 mm or more and 5 mm or less. According to the above configuration, (a) polypropylene-based resin particles can be easily formed from the melt-kneaded product of the polypropylene-based resin composition, and (b) polypropylene-based resin foamed particles having a high expansion ratio can be produced from the polypropylene-based resin particles. Then, when the polypropylene-based resin foamed particles are used for in-mold foam molding, there is an advantage that the mold is less likely to be poorly filled with the polypropylene-based resin foamed particles. Here, the average particle size of the polypropylene-based resin particles is an additive average value of the particle sizes measured for any 20 polypropylene-based resin foamed particles.

In one embodiment of the present invention, the average weight of the polypropylene-based resin particles is preferably 0.1 mg or more and 100 mg or less, and more preferably 0.3 mg or more and 10 mg or less. According to the above configuration, (a) polypropylene-based resin particles can be easily formed from the melt-kneaded product of the polypropylene-based resin composition, and (b) polypropylene-based resin foamed particles having a high expansion ratio can be produced from the polypropylene-based resin particles. Then, when the polypropylene-based resin foamed particles are used for in-mold foam molding, there is an advantage that the mold is less likely to be poorly filled with the polypropylene-based resin foamed particles. Here, the average weight of the polypropylene-based resin particles is an additive average value of the weights measured for any 10 polypropylene-based resin particles.

(1-2. Manufacturing method)
In one embodiment of the present invention, the polypropylene-based resin foamed particles can be produced as follows.

(I) The dispersion liquid containing the polypropylene-based resin particles, water, and silicate in a predetermined ratio, and the inorganic foaming agent containing carbon dioxide are housed in a pressure-resistant container, and (ii) the dispersion liquid is stirred. As a result, the polypropylene-based resin particles in the dispersion liquid are dispersed in the pressure-resistant container, and the temperature inside the pressure-resistant container is raised and increased to a predetermined temperature (at least above the softening point temperature of the polypropylene-based resin particles) and a predetermined pressure. After that, (iii) if necessary, keep the inside of the pressure-resistant container at the temperature after temperature rise for more than 0 minutes and 120 minutes or less, and (iv) then, in the pressure-resistant container in a pressure range lower than the internal pressure of the pressure-resistant container. The polypropylene-based resin foamed particles can be produced by releasing the dispersion liquid and foaming the polypropylene-based resin particles. The pressure range lower than the internal pressure of the pressure-resistant container is preferably atmospheric pressure. Here, the dispersion liquid contains an inorganic foaming agent.

The process of producing the polypropylene-based resin foamed particles from the polypropylene-based resin particles in this way is referred to as a "one-stage foaming step", and the obtained polypropylene-based resin foamed particles are referred to as "one-stage foamed particles". Further, the dispersion liquid in the steps after (ii) contains polypropylene-based resin particles, water, silicate, a foaming agent, etc., is housed in a pressure-resistant container, and is contained in a pressure-resistant container under stirring conditions. It is a mixed liquid in which an acid salt, a foaming agent, etc. are dispersed.

Here, when the temperature inside the pressure-resistant container is raised to the softening point temperature or higher, the temperature rise is such that the melting point of the polypropylene-based resin is −20 ° C. or higher, the melting point of the polypropylene-based resin is + 10 ° C. or lower, or the temperature of the polypropylene-based resin particles is increased. It is preferable to raise the temperature to a temperature in the range of a melting point of −20 ° C. or higher and a melting point of polypropylene-based resin particles of + 10 ° C. or lower in order to secure foamability. However, the temperature rise temperature is appropriately determined depending on the type of the polypropylene-based resin as a raw material and / or the desired expansion ratio of the polypropylene-based resin foamed particles, the DSC ratio described later, and the like. Appropriate changes may be required depending on the foaming agent used.

The melting point of the polypropylene-based resin particles was measured by the same method as that of the polypropylene-based resin.

The amount of polypropylene-based resin particles used in the dispersion used in one embodiment of the present invention is preferably 25 parts by weight or more and 100 parts by weight or less, and 30 parts by weight or more and 90 parts by weight or less with respect to 100 parts by weight of water. More preferred. When the amount of polypropylene-based resin particles used is less than (a) 25 parts by weight with respect to 100 parts by weight of water, productivity decreases, and (b) when it exceeds 100 parts by weight, the stability of the dispersion liquid becomes stable. It tends to decrease (in other words, the dispersion of the polypropylene-based resin particles becomes poor).

Examples of the silicate used in one embodiment of the present invention include clay minerals such as kaolin, talc and clay. These may be used alone or in combination of two or more. In this production method, the silicate is preferably kaolin. According to the above configuration, there is an advantage that the dispersion of polypropylene-based resin particles can be easily stabilized even when the amount of silicate added is small. In the dispersion used in one embodiment of the present invention, the amount of silicate used is preferably 0.05 parts by weight or more and 0.25 parts by weight or less with respect to 100 parts by weight of water. It is more preferably 05 parts by weight or more and 0.24 parts by weight or less, and further preferably 0.05 parts by weight or more and 0.23 parts by weight or less.

When the amount of silicate used is less than (a) 0.05 parts by weight with respect to 100 parts by weight of water, it tends to cause poor dispersion, and (b) when it is 0.25 parts by weight or more, it is in the mold. It tends to cause poor fusion between polypropylene-based resin foam particles during foam molding.

When the stability of the dispersion liquid is lowered, a plurality of polypropylene-based resin particles may be coalesced or agglomerated in the pressure-resistant container. As a result, (a) fused polypropylene-based resin foamed particles can be obtained, (b) lumps of polypropylene-based resin particles remain in the pressure-resistant container, and polypropylene-based resin foamed particles cannot be produced, or (c). Alternatively, the productivity of the polypropylene-based resin foam particles may decrease.

In one embodiment of the present invention, it is preferable to further use a dispersion aid in order to improve the stability of the dispersion in the pressure-resistant container. Examples of the dispersion aid include sodium dodecylbenzene sulfonate, sodium alkane sulfonate, sodium alkyl sulfonate, sodium alkyl diphenyl ether disulfonate, sodium α-olefin sulfonate, and the like. These may be used alone or in combination of two or more. The amount of the dispersion aid used varies depending on the type of the dispersion aid and the type and amount of the polypropylene-based resin particles used. In the dispersion liquid used in one embodiment of the present invention, the amount of the dispersion aid used is preferably 0.001 part by weight or more and 0.2 part by weight or less with respect to 100 parts by weight of water. If the amount of the dispersion aid used is less than 0.001 part by weight and more than 0.2 part by weight with respect to 100 parts by weight of water, it may cause poor dispersion.

The foaming agent used in one embodiment of the present invention is an inorganic foaming agent containing carbon dioxide, preferably carbon dioxide alone. Examples of the inorganic foaming agent that can be used in combination with carbon dioxide include water, nitrogen, and air (a mixture of oxygen, nitrogen, and carbon dioxide).

In one embodiment of the present invention, the amount of the foaming agent used is not limited and may be appropriately used according to the desired expansion ratio of the polypropylene-based resin foamed particles, but the amount of the foaming agent used is usually water. It is preferably 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight.

When water is used in combination with carbon dioxide as the foaming agent, the water in the dispersion liquid in the pressure-resistant container can be used as the foaming agent. Specifically, when water in the dispersion liquid is used as the foaming agent, it is preferable to preliminarily contain the water-absorbent compound in the polypropylene-based resin particles. As a result, the polypropylene-based resin particles can easily absorb the water of the dispersion liquid in the pressure-resistant container, and as a result, the water can be easily used as a foaming agent.

The pH of the dispersion in one embodiment of the present invention is 5 or more and 9 or less. If the pH of the dispersion is less than (a) 5, it causes corrosion of the equipment when the same equipment is used for a long period of time, and if it exceeds (b) 9, the dispersion of polypropylene-based resin particles becomes unstable. It becomes difficult to obtain polypropylene-based resin foam particles.

When a silicate is used as a dispersant, a method of adding an acidic substance (pH adjuster) is generally adopted in order to adjust the zeta potential of the silicate to the positive electrode. However, the present inventor surprisingly disperses the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine at a pH near the neutral range even when a silicate is used as a dispersant. For the first time, I found that it has a stabilizing effect. Specifically, when a specific amount of the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine is used, even when the silicate is used as a dispersant, the equipment does not adjust the pH by adding an acidic substance. For the first time, it was found that the dispersion can be stabilized in the vicinity of the neutral range of pH 5 or more and 9 or less where there is no risk of corrosion.

Examples of the pH adjuster include (a) aluminum sulfate, citric acid, ammonium acetate and the like as acidic substances, and (b) sodium hydrogencarbonate and the like as basic substances.

The pressure-resistant container used during the production of polypropylene-based resin foam particles is not particularly limited, and may be any as long as it can withstand the pressure inside the pressure-resistant container and the temperature inside the pressure-resistant container set during the production of polypropylene-based resin foam particles. , Autoclave type pressure resistant container can be mentioned.

By the way, in order to obtain polypropylene-based resin foamed particles having a high foaming ratio, there is a method of increasing the amount of the foaming agent used in the one-step foaming step (hereinafter referred to as method 1). Further, as a method other than Method 1, polypropylene-based resin foamed particles (one-stage foamed particles) having a relatively low magnification (foaming ratio of about 2 to 35 times) are obtained in a one-step foaming step, and then foamed again to obtain a foaming ratio. It is also possible to adopt a method of increasing the value (hereinafter referred to as method 2).

Examples of the method 2 include methods including the following (i) to (iii). (I) In the one-stage foaming step, one-stage foamed particles having a foaming ratio of 2 times or more and 35 times or less are produced, and (ii) the one-stage foamed particles are placed in a pressure-resistant container and 0.1 MPa (gauge) with nitrogen, air, carbon dioxide or the like. Pressure) or more and 0.6 MPa (gauge pressure) or less to make the pressure inside the one-stage foamed particles higher than normal pressure, and then (iii) heat the one-stage foamed particles with steam or the like. This is a method of further foaming. The step of increasing the foaming ratio of the one-stage foamed particles as in Method 2 is called a "two-stage foaming step", and the polypropylene-based resin foamed particles obtained by the method of Method 2 are called "two-stage foamed particles".

[2. Polypropylene resin foam particles]
The polypropylene-based resin foamed particles according to another embodiment of the present invention are polypropylene-based resin foamed particles and contain a polypropylene-based resin, a silicate, and an aliphatic diethanolamine fatty acid ester and / or an aliphatic diethanolamine. , The total content of the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine is 0.2 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the polypropylene-based resin, and the polypropylene-based resin foamed particles. It is characterized in that the silicate is adhered to the surface.

According to the polypropylene-based resin foamed particles according to another embodiment of the present invention, it is possible to provide a polypropylene-based resin in-mold foam molded product having excellent quality. Specifically, polypropylene-based resin foamed particles that can satisfy the following (a) and (b) can be obtained: (d) to provide a polypropylene-based resin in-mold foam molded article having good fusion property; (E) To provide a polypropylene-based resin in-mold foam molded article, which suppresses deformation immediately after molding even at a high foaming ratio, thereby shortening the drying time.

The polypropylene-based resin foamed particles according to another embodiment of the present invention may further optionally contain other additives. Preferred embodiments of polypropylene resins, silicates, aliphatic diethanolamine fatty acid esters and / or aliphatic diethanolamines, and other additives that may be included in the polypropylene resin foam particles according to another embodiment of the present invention. , The above [1. Method for Producing Polypropylene Resin Foamed Particles] can be appropriately incorporated.

As a production method for producing polypropylene-based resin foamed particles according to another embodiment of the present invention, a conventionally known method may be adopted and is not particularly limited. As a production method for producing polypropylene-based resin foamed particles according to another embodiment of the present invention, the above-mentioned [1. Method for producing polypropylene-based resin foamed particles] is preferable. In other words, the above [1. Method for producing polypropylene-based resin foamed particles] can be used to produce polypropylene-based resin foamed particles according to another embodiment of the present invention.

In another embodiment of the present invention, the amount of silicate adhering to the surface of the polypropylene-based resin foam particles can be measured by ash content measurement based on the following formula:
Amount of silicate adhering to the surface of polypropylene-based resin foamed particles (ppm) = "Amount of ash of polypropylene-based resin foamed particles"-"Amount of ash of polypropylene-based resin particles used for producing polypropylene-based resin foamed particles".

The amount of ash is obtained by dividing the weight of the ash (after burning) of the polypropylene-based resin foamed particles or the polypropylene-based resin particles by the weight of the polypropylene-based resin foamed particles or the polypropylene-based resin particles before burning, respectively. It is calculated. When the amount of silicate attached to the surface of the polypropylene-based resin foamed particles determined from the above formula is 0, it can be said that the silicate is not attached to the surface of the polypropylene-based resin foamed particles.

The polypropylene-based resin foamed particles according to another embodiment of the present invention can be used for producing a polypropylene-based resin foamed molded article by in-mold foam molding. [2. [Polypropylene-based resin foamed particles], unless otherwise specified, the "polypropylene-based resin foamed molded article" is an in-mold foamed product using polypropylene-based resin foamed particles according to another embodiment of the present invention. It is intended to be a polypropylene-based resin in-mold foam molded product obtained by being manufactured by molding.

The polypropylene-based resin foamed particles according to another embodiment of the present invention contain the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine in a total amount of 0.2 parts by weight or more and 5 parts by weight with respect to 100 parts by weight of the polypropylene-based resin. It is preferable to include the following. According to the above configuration, it is possible to suppress the deformation of the polypropylene-based resin in-mold foam molded product immediately after molding.

In another embodiment of the present invention, it is preferable that the silicate attached to the surface of the polypropylene-based resin foamed particles is kaolin. The silicate adhering to the surface of the polypropylene-based resin foamed particles according to another embodiment of the present invention is the silicate contained in the dispersion liquid in the production of the polypropylene-based resin foamed particles. Regarding the dispersion liquid, the above [1. Method for producing polypropylene-based resin foam particles] can be appropriately referred to. When producing polypropylene-based resin foamed particles according to another embodiment of the present invention, by using kaolin as a silicate contained in the dispersion liquid, polypropylene-based resin foamed particles having kaolin adhered to the surface can be obtained. Can be done.

In another embodiment of the present invention, the amount of silicate adhered to the surface of the polypropylene-based resin foam particles is preferably 200 ppm or more and 2000 ppm or less with respect to the weight of the polypropylene-based resin particles used. With the above configuration, (a) the fusion of polypropylene-based resin foamed particles to each other during in-mold foam molding using polypropylene-based resin foamed particles is satisfactory, and (b) polypropylene-based resin foamed particles are satisfied. It has an advantage that the dispersion of polypropylene-based resin particles tends to be stabilized when the polypropylene-based resin particles are produced. The amount of silicate adhering to the surface of the polypropylene-based resin foamed particles can be appropriately changed by adjusting the amount of silicate contained in the dispersion liquid in the production of the polypropylene-based resin foamed particles. Further, a more preferable upper limit value of the adhered amount of silicate may be appropriately selected based on the expansion ratio of the polypropylene-based resin foamed particles.

The shape of the polypropylene-based resin foamed particles according to another embodiment of the present invention is preferably spherical or substantially spherical in consideration of the filling property into the mold when foaming and molding in the mold using the polypropylene-based resin foamed particles. However, it is not limited to these. For example, in order to impart sound absorption and / or water permeability to the polypropylene-based resin in-mold foam molded product, there is a case where a polypropylene-based resin in-mold foam molded product having voids is intentionally manufactured. In such a case, columnar, elliptical, rectangular parallelepiped, and tubular (straw-shaped) polypropylene-based resin foam particles can be used.

In another embodiment of the present invention, the average diameter (also referred to as the average particle diameter) of the polypropylene-based resin foamed particles when the polypropylene-based resin foamed particles are spherical or substantially spherical is not particularly limited. The average diameter of the polypropylene-based resin foamed particles according to another embodiment of the present invention varies depending on the size of the polypropylene-based resin particles before foaming, the expansion ratio, and the like, but is 0.5 mm or more and 10 mm or less. It is preferable, 1 mm or more and 7 mm or less is more preferable, and 2 mm or more and 5 mm or less is further preferable. Here, the average diameter of the polypropylene-based resin foamed particles is an arithmetic mean value of the diameters measured for any 20 polypropylene-based resin foamed particles.

When the average diameter of the polypropylene-based resin foamed particles according to another embodiment of the present invention is (a) less than 0.5 mm, the workability when foaming and molding in the mold using the polypropylene-based resin foamed particles is not good. (B) When it exceeds 10 mm, the shape of the foamed product in the polypropylene resin mold is limited when the polypropylene resin foam particles are used for foam molding in the polypropylene resin mold. Tend. The case where the shape of the molded body is restricted is, for example, the case where the polypropylene-based resin mold in-foam molding having a thin-walled portion cannot be manufactured.

The average weight of the polypropylene-based resin foamed particles according to another embodiment of the present invention is substantially the same as the polypropylene-based resin particles used for producing the polypropylene-based resin foamed particles, and is 0.1 mg / grain or more and 100 mg / grain. It is preferably less than or equal to grains, and more preferably 0.3 mg / grain or more and 10 mg / grain or less. Here, the average weight of the polypropylene-based resin foamed particles is an arithmetic mean value of the weights measured for any 10 polypropylene-based resin foamed particles.

The expansion ratio of the polypropylene-based resin foamed particles according to another embodiment of the present invention is preferably 2 times or more and 60 times or less, and more preferably 3 times or more and 40 times or less. Further, in order to obtain a polypropylene-based resin foam in-mold foam molded product that can be suitably used as a buffer packaging material for electronic parts and mechanical parts, the expansion ratio of the polypropylene-based resin foam particles may be 18 times or more and 60 times or less. It is preferably 18 times or more and 40 times or less, more preferably. In a polypropylene-based resin mold having a high foaming ratio, deformation immediately after molding is suppressed by using the polypropylene-based resin foamed particles according to another embodiment of the present invention having a foaming ratio of 18 times or more and 60 times or less. A foam molded product can be obtained. The polypropylene-based resin foamed particles having a foaming ratio of 18 times or more and 60 times or less may be the one-stage foamed particles obtained by the above-mentioned method 1, or may be the two-stage foamed particles obtained by the method 2. May be good. In the present specification, the expansion ratio is the density of the polypropylene-based resin composition before foaming, the weight of the polypropylene-based resin foamed particles, and the volume obtained by submerging the polypropylene-based resin foamed particles in water (or submerged in ethanol). It is a true magnification that can be calculated from.

The apparent density of the polypropylene-based resin foamed particles according to another embodiment of the present invention is preferably 15 g / L or more and 29 g / L or less, and more preferably 16 g / L or more and 28 g / L or less. By using the polypropylene-based resin foamed particles according to another embodiment of the present invention, which has an apparent density of 15 g / L or more and 29 g / L or less, deformation immediately after molding is suppressed, and a polypropylene-based resin having a high foaming ratio is suppressed. An in-mold foam molded product can be obtained. The method for measuring the apparent density will be described in detail in Examples.

The polypropylene-based resin foamed particles according to another embodiment of the present invention preferably have an open cell ratio of 0% to 10%, more preferably 0% to 9%, and 0% to 8%. It is more preferable to have. Since the polypropylene-based resin foamed particles according to another embodiment of the present invention have an open cell ratio within the above range, it is possible to suppress shrinkage of the polypropylene-based resin-molded foamed molded product after molding. Therefore, it has an advantage that it can sufficiently withstand use and a good polypropylene-based resin in-mold foam molded product can be obtained.

The polypropylene-based resin foamed particles according to another embodiment of the present invention have two melting peaks as shown in FIG. 1 in the DSC curve obtained when the calorific value of the polypropylene-based resin foamed particles is measured by the DSC method. It is preferably polypropylene-based resin foam particles. Polypropylene resin foamed particles having such two melting peaks can be produced by a known method.

The DSC curve of the polypropylene-based resin foamed particles is a curve obtained when 5 to 6 mg of the polypropylene-based resin foamed particles are heated from 40 ° C. to 220 ° C. at a heating rate of 10 ° C./min by the DSC method. An example of such a DSC curve is shown in FIG.

FIG. 1 will be described in more detail. In FIG. 1, there are two peaks in which the value of DSC becomes small. Of the two peaks, the peak on the low temperature side is referred to as a melting peak based on the melting point on the low temperature side, and the other peak on the high temperature side is referred to as a melting peak based on the melting point on the high temperature side. The maximum point between the melting peak based on the melting point on the low temperature side and the melting peak based on the melting point on the high temperature side is defined as point A. Point B is the intersection of the line from the melting peak based on the melting point on the low temperature side toward the low temperature side and the baseline on the low temperature side (which is also the melting start baseline). Further, the intersection of the line from the melting peak based on the melting point on the high temperature side toward the high temperature side and the baseline on the high temperature side (which is also the melting end baseline) is defined as the point C. Here, the melting start base from the maximum point (point A) between (a) the melting peak based on the low temperature side melting point of the DSC curve and (b) the melting peak based on the low temperature side melting point and the high temperature side melting point. The calorific value surrounded by the tangent to the line (that is, the linear segment AB) is defined as the melting peak calorific value Ql (J / g) based on the melting point on the low temperature side. Further, (c) a melting peak based on the high temperature side melting point of the DSC curve, and (d) a tangent line from the maximum point between the melting peak based on the low temperature side melting point and the melting peak based on the high temperature side melting point to the melting end baseline (c). That is, the calorific value surrounded by the linear segment AC) is defined as the melting peak calorific value Qh (J / g) based on the melting point on the high temperature side. The sum of the melting peak heat quantity (Ql) based on the melting point on the low temperature side and the melting peak heat quantity (Qh) based on the melting point on the high temperature side is the total heat quantity of the melting peak. Here, the ratio of the melting peak calorie (Qh) based on the melting point on the high temperature side to the total calorific value of the melting peak (hereinafter, may be referred to as “DSC ratio” or “high temperature calorie ratio”) is expressed by the following formula.

DSC ratio (%) = (Qh / (Ql + Qh)) × 100.

The polypropylene-based resin foamed particles according to another embodiment of the present invention preferably have a DSC ratio of 10% or more and 50% or less, and more preferably 15% or more and 45% or less. When the DSC ratio is within the range, there is an advantage that a wide range of molding processing conditions can be selected in the in-mold foam molding using polypropylene-based resin foam particles.

By the way, the DSC ratio can be adjusted by changing the following (a) and / or (b) in the production of polypropylene-based resin foamed particles: (a) temperature after temperature rise in the pressure resistant container. (Hereinafter, also referred to as the temperature rise temperature); (b) The holding time for holding the inside of the pressure-resistant container at the temperature rise temperature from after the temperature rise to the discharge of the dispersion liquid in the pressure-resistant container. For example, when the temperature rise temperature (in other words, the foaming temperature) is lowered, the DSC ratio tends to increase, and even if the holding time is lengthened, the DSC ratio tends to increase.

Therefore, by conducting several experiments in which the temperature rise temperature (foaming temperature) and / or the holding time was changed and obtaining a DSC curve for each of these experiments, the temperature rise temperature (foaming temperature) and / or the temperature rise were obtained. / Alternatively, the relationship between the retention time and the DSC ratio can be grasped. As a result, polypropylene-based resin foamed particles having a desired DSC ratio can be easily obtained.

The average bubble diameter of the polypropylene-based resin foamed particles in another embodiment of the present invention is preferably 80 μm or more and 500 μm or less, more preferably 90 μm or more and 360 μm or less, and further preferably 105 μm or more and 330 μm or less. When the average bubble diameter of the polypropylene-based resin foamed particles is less than 80 μm, the surface beauty of the polypropylene-based resin foamed molded product tends to be deteriorated, and further, the compressive strength of the polypropylene-based resin foamed molded product is also high. Tends to decline. When the average bubble diameter of the polypropylene-based resin foamed particles exceeds 500 μm, the uniformity of the bubble diameter of the polypropylene-based resin foamed foam in the mold tends to decrease, and as a result, the polypropylene-based resin foamed foam in the mold tends to have a reduced uniformity. The surface beauty tends to decrease. Further, when the average cell diameter of the polypropylene-based resin foamed particles is to be larger than 500 μm, the above-mentioned high-temperature calorific value ratio tends to be small, and as a result, the compressive strength of the polypropylene-based resin foamed molded product is formed. Tends to decrease.

[3. Effervescent molded product in polypropylene resin mold]
The foamed molded product in a polypropylene resin mold according to another embodiment of the present invention contains a polypropylene resin, a silicate, and an aliphatic diethanolamine fatty acid ester and / or an aliphatic diethanolamine, and the aliphatic diethanolamine. When the total content of the fatty acid ester and / or the aliphatic diethanolamine is 0.2 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the polypropylene-based resin, and the apparent density is 17 g / L or more and 33 g / L or less. It is characterized by being.

Since the polypropylene-based resin in-mold foam molded product according to another embodiment of the present invention has the above-mentioned structure, it has excellent quality such as good fusion property. Further, since the polypropylene-based resin in-mold foam molded product according to another embodiment of the present invention has the above-mentioned structure, deformation immediately after molding can be suppressed even at a high foaming ratio. Therefore, it has an advantage that the drying time after in-mold foam molding is short.

The polypropylene-based resin mold in-foamed molded article according to another embodiment of the present invention may further contain other additives, optionally. Addition of polypropylene resin, silicate, aliphatic diethanolamine fatty acid ester and / or aliphatic diethanolamine, carbon dioxide, and other additions which may be contained in the polypropylene-based resin in-mold foam molded product according to another embodiment of the present invention. A preferred embodiment of the agent is described in [1. Method for Producing Polypropylene Resin Foamed Particles] and the above [2. The description in the section of polypropylene-based resin foamed particles] may be appropriately incorporated.

The apparent density of the polypropylene-based resin mold in-foamed molded article according to another embodiment of the present invention is 17 g / L or more and 33 g / L or less, and particularly preferably 17 g / L or more and 32 g / L or less. The polypropylene-based resin in-mold foam molded product according to another embodiment of the present invention has an advantage that deformation immediately after molding can be suppressed even if the apparent density is within the above range. The method for measuring the apparent density will be described in detail in Examples.

The polypropylene-based resin in-mold foam molded product according to another embodiment of the present invention can be obtained by in-mold foam molding of polypropylene-based resin foamed particles. When polypropylene-based resin foam particles are used for in-mold foam molding, as a method of filling polypropylene-based resin foam particles in a mold or the like, for example, there are in-mold filling methods such as the following (A) to (C):
(A) A method of injecting an inorganic gas such as air into polypropylene-based resin foamed particles in advance (applying internal pressure) to fill the polypropylene-based resin foamed particles with foaming ability.
(B) A method of filling polypropylene-based resin foam particles without applying internal pressure (that is, the internal pressure remains the same as atmospheric pressure).
(C) A method in which polypropylene-based resin foamed particles are compressed by transport air during filling in a mold to increase the internal pressure of the polypropylene-based resin foamed particles and at the same time to fill the polypropylene-based resin foamed particles. These methods may be used in combination, and other conventionally known in-mold filling methods may also be used.

Examples of the method for producing the polypropylene-based resin in-mold foam molded product according to another embodiment of the present invention from polypropylene-based resin foamed particles include methods including the following (i) to (iv). (I) Polypropylene resin foam particles are filled in a molded mold that can be closed but cannot be closed with the mold slightly open, and (ii) water vapor or the like is used as a heating medium at 0.05 MPa (gauge pressure). ) Or more and 0.5 MPa (gauge pressure) or less heated steam pressure for 3 seconds or more and 30 seconds or less to fuse the polypropylene-based resin foamed particles to each other (iii). After that, the molding die is cooled to the extent that the deformation of the foamed molded product in the polypropylene resin mold after taking out the foamed molded product in the polypropylene resin mold from the molding die can be suppressed by water cooling, and then (iv) molding is performed. A method in which the mold is opened and taken out from the molding mold to form a foamed molded product in a polypropylene resin mold. In (i), the cracking amount is the opening width of the mold before filling the polypropylene-based resin foam particles.

Conventionally known polypropylene-based resin foamed particles can be used as the polypropylene-based resin foamed particles used for producing the polypropylene-based resin in-mold foamed molded product according to another embodiment of the present invention, and are not particularly limited. Examples of the polypropylene-based resin foamed particles used for producing the polypropylene-based resin-molded in-foamed foam according to another embodiment of the present invention include (a) the above [1. Polypropylene-based resin foamed particles produced by the production method described in the section [Method for producing polypropylene-based resin foamed particles], or (b) the above-mentioned [2. Polypropylene-based resin foamed particles] are preferably polypropylene-based resin foamed particles. In other words, (a) the above [1. Polypropylene-based resin foamed particles produced by the production method described in the section [Method for producing polypropylene-based resin foamed particles], or (b) the above-mentioned [2. By using the polypropylene-based resin foamed particles described in the item [Polypropylene-based resin foamed particles], the polypropylene-based resin in-mold foam molded product according to another embodiment of the present invention can be obtained.

An example of the polypropylene-based resin in-mold foam molded article according to another embodiment of the present invention will be described with reference to FIGS. 2 and 3. FIG. 2 is a perspective view showing a schematic configuration of a foamed molded article 1 in a polypropylene resin mold according to another embodiment of the present invention, and FIG. 3 is a polypropylene resin according to another embodiment of the present invention. FIG. 3 is a plan view of the in-mold foam molded product 1 viewed along the x direction.

As shown in FIG. 2, the polypropylene-based resin mold inner foam molded body 1 is (a) rectangular in a plan view along the z direction, and (b) has an opening at an end in the z direction. , (C) Box-shaped. The polypropylene-based resin mold inner foam molded body 1 has one bottom plate and four side walls. Of the four side walls, (a) a set (ie, two) of facing side walls along the x direction has a plurality of protrusions 2 inside the container 1 and (b) in the y direction. Along the side wall of the other set (ie, the other two) is an end in the z direction, with a notch at the end on the opening side. The notch is provided in the center in the y direction, and is configured so that the length in the y direction becomes shorter from the opening toward the bottom plate, that is, it has a tapered shape.

As shown in FIG. 2, in the polypropylene-based resin mold inner foam molded product 1, the length in the x direction at the center in the y direction is b, the length in the x direction at the end in the y direction is c, and the length in the y direction. Is d, and the length in the z direction is e. Further, as shown in FIG. 3, a side wall having a notch, in other words, a side wall along the y direction, has a length in the z direction at the center of the y direction as f. In other words, the length f can be said to be the length of the perpendicular line from the lower end portion in the z direction to the notch portion in the side wall having the notch portion. Further, in the notch portion, the length of the notch portion in the y direction at the end portion in the z direction is g, and the length of the end portion in the direction 180 ° opposite to the z direction of the notch portion in the y direction. Let be h.

One embodiment of the present invention may have the following configuration.

[1] A method for producing polypropylene-based resin foamed particles using a dispersion containing polypropylene-based resin particles, water, and silicate, and an inorganic foaming agent containing carbon dioxide. (A) The polypropylene-based resin. The particles consisted of a polypropylene-based resin composition, and (B) the polypropylene-based resin composition contained an aliphatic diethanolamine fatty acid ester and / or an aliphatic diethanolamine in total, with respect to 100 parts by weight of the polypropylene-based resin. It contains 2 parts by weight or more and 5 parts by weight or less, (C) the dispersion liquid contains 100 parts by weight of water, (a) 25 parts by weight or more and 100 parts by weight or less of the polypropylene-based resin particles, and (b) the said. A method for producing polypropylene-based resin foamed particles, which comprises 0.05 parts by weight or more and 0.25 parts by weight or less of silicate, and (D) the pH of the dispersion is 5 or more and 9 or less.

[2] The aliphatic diethanolamine fatty acid ester is a compound represented by the following general formula (1), and the aliphatic diethanolamine is a compound represented by the following general formula (2). The method for producing a polypropylene-based resin foamed particle according to [1].

（Ｒ^１は、炭素数１２～２４のアルキル基、Ｒ^２は炭素数１１～２３のアルキル基を示し、Ｒ^１とＲ^２は同じでもよく、異なっていてもよい）

(R ¹ represents an alkyl group having 12 to 24 carbon atoms, R ² represents an alkyl group having 11 to 23 carbon atoms, and R ¹ and R ² may be the same or different).

（Ｒ^３は、炭素数１２～２４のアルキル基を示す）。

(R ³ represents an alkyl group having 12 to 24 carbon atoms).

[3] The polypropylene-based resin foam according to [1] or [2], wherein the aliphatic diethanolamine fatty acid ester is stearyl diethanolamine monostearic acid ester, and the aliphatic diethanolamine is stearyl diethanolamine. How to make particles.

[4] Polypropylene resin foamed particles, which contain a polypropylene resin, a silicate, and an aliphatic diethanolamine fatty acid ester and / or an aliphatic diethanolamine, and contain the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine. The total content of the polypropylene-based resin is 0.2 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the polypropylene-based resin, and the silicate is adhered to the surface of the polypropylene-based resin foamed particles. Characterized by polypropylene-based resin foam particles.

[5] The aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine are contained in a total amount of 0.2 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the polypropylene-based resin [4]. The polypropylene-based resin foamed particles described in.

[6] The polypropylene-based resin foamed particles according to [4] or [5], wherein the silicate is kaolin.

[7] The amount of the silicate adhered to the surface of the polypropylene-based resin foamed particles is 200 ppm or more and 2000 ppm or less with respect to the weight of the polypropylene-based resin foamed particles [4]. The polypropylene-based resin foamed particles according to any one of [6].

[8] The apparent density of the polypropylene-based resin foamed particles in the first half is 15 g / L or more and 29 g / L or less, and the open cell ratio is 0% to 10% [4] to [7]. The polypropylene-based resin foamed particles according to any one of the above.

[9]
The polypropylene resin 100 contains a polypropylene resin, a silicate, and an aliphatic diethanolamine fatty acid ester and / or an aliphatic diethanolamine, and the total content of the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine is 100. A foamed molded product in a polypropylene resin mold, which is 0.2 parts by weight or more and 5 parts by weight or less with respect to parts by weight, and has an apparent density of 17 g / L or more and 33 g / L or less.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention. Further, by combining the technical means disclosed in each embodiment, new technical features can be formed.

Next, one embodiment of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

The polypropylene-based resins and additives used in Examples and Comparative Examples are as follows.

(1) Polypropylene-based resin / Polypropylene-based resin A [manufactured by Prime Polymer Co., Ltd., F227A]: Ethylene / propylene random copolymer having a melting point of 143 ° C., an ethylene content of 3.6% by weight, and MI 7.0 g / 10 min. ) Polypolydiethanolamine fatty acid ester and aliphatic diethanolamine / stearyldiethanolamine monostearic acid ester [Electrostripper TS-6B manufactured by Kao Co., Ltd.]
・ Stearyl diethanolamine [manufactured by Tokyo Chemical Industry Co., Ltd., reagent]
・ Lauryl diethanolamine [manufactured by Wako Pure Chemical Industries, Ltd., reagent]
(3) Additive (water-absorbing compound)
-Polyethylene glycol [Lion Corporation, PEG # 300]
・ Glycerin [Purified Glycerin D manufactured by Lion Corporation]
(4) Foaming agent / carbon dioxide [manufactured by Air Water Inc.]
(5) Dispersant Kaolin [BASF, ASP-170]
・ Tricalcium phosphate [manufactured by Taihei Kagaku Sangyo Co., Ltd.]
(6) Dispersion aid, sodium dodecylbenzene sulfonate [Neoperex G-15, manufactured by Kao Corporation]
(7) pH adjuster, aluminum sulfate [manufactured by Wako Pure Chemical Industries, Ltd.] (acidic substance)
・ Citric acid [manufactured by Wako Pure Chemical Industries, Ltd.] (acidic substance)
・ Ammonium acetate [manufactured by Wako Pure Chemical Industries, Ltd.] (acidic substance)
-Sodium hydrogen carbonate [manufactured by Wako Pure Chemical Industries, Ltd.] (basic substance).

(8) Bubble nucleating agent, talc [Tarkhan powder PK-S manufactured by Hayashi Kasei Co., Ltd.]
Evaluation in Examples and Comparative Examples was performed by the following method.

(Dispersion stability)
The dispersion stability of the polypropylene-based resin particles when producing the polypropylene-based resin foam particles was judged according to the following criteria.
⊚: The polypropylene-based resin particles were completely foamed without agglomeration of the polypropylene-based resin particles, and the ratio of the amount of the polypropylene-based resin remaining in the can after foaming to the amount of the polypropylene-based resin before foaming was It is 0% or more and less than 0.2%.
◯: Foaming of polypropylene-based resin particles is completed without agglomeration of polypropylene-based resin particles, and the ratio of the amount of polypropylene-based resin remaining in the can after foaming to the amount of polypropylene-based resin before foaming is It is 0.2% or more and less than 2.0%.
Δ: The polypropylene-based resin particles were completely foamed without agglomeration of the polypropylene-based resin particles, and the ratio of the amount of the polypropylene-based resin remaining in the can after foaming to the amount of the polypropylene-based resin before foaming was It is 2.0% or more and less than 5.0%.
X: The following (a) or (b): (a) dispersion is unstable and polypropylene-based resin particles are agglomerated in the can, and polypropylene-based resin foamed particles cannot be obtained; (b) polypropylene-based resin. Foaming of polypropylene-based resin particles is completed without agglomeration of the particles, but the ratio of the amount of polypropylene-based resin remaining in the can after foaming to the amount of polypropylene-based resin before foaming is 5.0%. That is all.
The same applies to the following, but ⊚ indicates that it is very good, ○ indicates that it is good, Δ indicates that it is within the allowable range, and × indicates that it is defective. ..

(DSC ratio of polypropylene-based resin foam particles (high temperature calorie ratio))
Using a differential scanning calorimeter DSC [manufactured by Seiko Instruments Co., Ltd .: DSC6200 type], 5 to 6 mg of polypropylene-based resin foamed particles are heated from 40 ° C. to 220 ° C. at a heating rate of 10 ° C./min to obtain a DSC curve. Got An example of the obtained DSC curve is shown in FIG. The obtained DSC curve shows two melting peaks: Ql (J / g), which is the melting peak calorie based on the melting point on the low temperature side, and Qh (J / g), which is the melting peak calorie based on the melting point on the high temperature side. ing. The ratio of the heat of the melting peak based on the melting point on the high temperature side to the total heat of the melting peak (that is, the DSC ratio) was determined by the above-mentioned formula ((Qh / (Ql + Qh)) × 100 (%)). The details of the melting peak calories Ql and Qh are as described above.

(Average cell diameter of polypropylene-based resin foam particles)
Careful attention was paid not to destroy the bubble film (cell film) of the obtained polypropylene-based resin foamed particles, and approximately the center of the polypropylene-based resin foamed particles was cut. Next, the cut surface was observed using a microscope [manufactured by KEYENCE: VHX digital microscope], and an observation photograph was obtained. In the observation photograph, a line segment corresponding to a length of 1000 μm was drawn on the portion excluding the surface layer portion, the number of bubbles n through which the line segment passed was measured, and the bubble diameter was calculated from the formula of 1000 / n (μm). The same operation was performed with 10 polypropylene-based resin foamed particles, and the average value of the bubble diameters calculated for each was taken as the average bubble diameter of the polypropylene-based resin foamed particles.

(Expansion magnification of polypropylene-based resin foam particles)
The weight w (g) of the polypropylene-based resin foamed particles having a bulk volume of about 50 cm ³ was determined. Further, the volume v (cm ³ ) of the polypropylene-based resin foamed particles was determined by submerging the polypropylene-based resin foamed particles in ethanol. From the weight w (g) and the volume v (cm ³ ), and the density d (g / cm ³ ) of the polypropylene-based resin composition before foaming, the expansion ratio of the polypropylene-based resin foamed particles was determined by the following formula. .. The density d of the polypropylene-based resin composition was 0.9 g / cm ³ . Further, the polypropylene-based resin composition before foaming has the same meaning as the polypropylene-based resin particles before foaming.

Foaming magnification of polypropylene-based resin foamed particles = d × v / w.

(Apparent density of polypropylene-based resin foam particles)
The polypropylene-based resin foamed particles were gently poured into a wide-mouthed 10-liter container until it overflowed, and then the mouth of the 10 L container was scraped off so that the polypropylene-based resin foamed particles became 10 L. After measuring the weight of the polypropylene-based resin foam particles contained in the 10 L container, the particles were divided by a volume of 10 L to obtain an apparent density. The apparent density is expressed in units of g / L.

(Continuous cell ratio of polypropylene-based resin foamed particles)
The obtained polypropylene-based resin foam particles were subjected to the method described in Procedure C (PROSEDURE C) of ASTM D2856-87 using an air comparative hydrometer [manufactured by Tokyo Science Co., Ltd., Model 1000]. Then, the volume Vc (cm ³ ) was measured. Then, the total amount of the polypropylene-based resin foamed particles after measuring Vc was submerged in ethanol contained in a measuring cylinder. Then, the apparent volume Va (cm ³ ) of the polypropylene-based resin foamed particles was determined from the amount of increase in the position of ethanol in the graduated cylinder (that is, by these methods also called submersion methods). The open cell ratio of the polypropylene-based resin foamed particles was calculated by the following formula.

Open cell ratio (%) = (Va-Vc) x 100 / Va
Here, except for Example 20, the open cell ratio is the open bubble ratio of the two-stage foamed particles. In Example 20, since the two-stage foamed particles are not produced, the open cell ratio is that of the one-stage foamed particles. However, for convenience, in Table 3, the open cell ratio of the one-stage foamed particles of Example 20 is described in the column of open cell ratio in the item of bead quality of two-stage foaming, and is annotated as (one stage). ..

(Amount of dispersant adhered to the surface of polypropylene-based resin foam particles)
By the method described above, the amount of the dispersant adhered (ppm) on the surface of the obtained polypropylene-based resin foam particles was measured. Here, except for Example 20, the amount of the dispersant attached is the amount of the dispersant of the two-stage foamed particles. In Example 20, since the two-stage foamed particles are not produced, the amount of the dispersant adhered is that of the one-stage foamed particles. However, for convenience, in Table 3, the amount of the dispersant adhered to the one-stage foamed particles of Example 20 is described in the amount of the dispersant adhered in the item of bead quality of the two-stage foaming, and is annotated as (one step). ing.

(Apparent density of foam molded product (plate shape) in polypropylene resin mold)
The length, width, and thickness of the obtained polypropylene-based resin mold in-foam molded product (plate-shaped) were measured, and the volume of the polypropylene-based resin-based in-foamed molded product (plate-shaped) was calculated. Then, the weight of the polypropylene-based resin mold in-foam molded product (plate-shaped) was measured, and the weight was divided by the volume of the polypropylene-based resin-based in-foamed molded product (plate-shaped) to obtain an apparent density. The apparent density is expressed in units of g / L.

(Fusionability of foam molded product (plate shape) in polypropylene resin mold)
A notch with a depth of 10 mm (in other words, 10 mm in the thickness direction) is made in the center of the obtained polypropylene-based resin mold in-foamed molded product (plate shape) (thickness 50 mm) in the length direction and the width direction. The foamed molded product in the polypropylene resin mold was broken along the line. The fracture surface was observed, and the fusion property of the polypropylene-based resin mold in-foamed molded product (plate shape) was evaluated according to the following criteria.
◯: The broken ratio of the foamed particles is 60% or more ×: The broken ratio of the foamed particles is less than 60%.

(Deformation amount after 1 hour of molding of the foam molded body (box shape) in the polypropylene resin mold)
After 1 hour has passed from the molding of the box-shaped in-foam foam molded product (box-shaped) shown in FIGS. 2 and 3, the amount of deformation (cb) (the length in the x-direction at the end in the y-direction) The difference from the length in the x direction at the center in the y direction) was measured and evaluated according to the following criteria. The amount of deformation indicates the degree of deformation of the polypropylene-based resin mold in-foamed molded product immediately after molding.
⊚: Deformation amount is 0 mm or more and less than 3 mm ○: Deformation amount is 3 mm or more and less than 6 mm Δ: Deformation amount is 6 mm or more and less than 10 mm ×: Deformation amount is 10 mm or more.

(Equipment corrosiveness)
100 mL of the dispersion liquid containing the foaming agent supplied to the pressure-resistant container was collected, and the iron plate (5 cm × 5 cm × 3 mm) was immersed in the collected dispersion liquid. The appearance of the iron plate 7 days after being immersed in the dispersion was observed, and the equipment corrosiveness was judged by the following judgment.
◯: No rust is generated on the iron plate ×: Rust is generated on the iron plate.

(Mold contamination)
Using polypropylene-based resin foam particles, continuous in-mold foam molding of 1000 shots (that is, 1000 times) was performed. After that, the core vent (also referred to as steam hole) of the mold was observed, and the mold contamination was judged by the following judgment.
◯: There is no clogging in the core vent ×: The core vent is clogged even a little.

<Examples 1 to 20, Comparative Examples 1 to 16, Reference Examples 1 to 7>
[Preparation of polypropylene resin particles]
The following (a) and (b) were mixed to obtain a mixture: (a) polypropylene-based resins by type and weight shown in Tables 1 to 6, aliphatic diethanolamine fatty acid esters, aliphatic diethanolamines, and additions. Agent; and (b) 0.05 parts by weight of talc. The mixture was kneaded (resin temperature 210 ° C.) with a 50 mmφ extruder to obtain a kneaded product. The kneaded product was extruded into a strand shape from the tip of an extruder and then granulated by cutting the extruded kneaded product to produce polypropylene-based resin particles (1.2 mg / grain). Here, as shown in Table 4, Comparative Example 8 discontinued the production of polypropylene-based resin particles. Further, as shown in Table 5, in Comparative Examples 12 to 14, polypropylene-based resin particles could not be produced.

[Preparation of polypropylene-based resin foam particles]
For the examples, comparative examples and reference examples in which polypropylene-based resin particles could be produced, polypropylene-based resin foamed particles were produced by the following methods. In a 300 L pressure-resistant container, (a) a dispersion liquid (water, prepared polypropylene-based resin particles, kaolin or tertiary calcium phosphate as a dispersant, and a pH adjuster if necessary, are placed in the weights shown in Tables 1 to 6). A portion (based on 100 parts by weight of water) was further charged, and 0.06 parts by weight of sodium dodecylbenzene sulfonate was charged as a dispersion aid, and (b) 2.6 parts by weight of carbon dioxide was charged. While stirring the dispersion liquid containing the foaming agent (carbon dioxide), the temperature and pressure in the pressure-resistant container are adjusted to the predetermined foaming temperature (temperature in the pressure-resistant container) and the predetermined foaming pressure (pressure in the pressure-resistant container, shown in Tables 1 to 6). The temperature was raised and the pressure was increased up to the gauge pressure). After the temperature and pressure in the pressure-resistant container reached the predetermined foaming temperature and foaming pressure, the temperature and pressure in the pressure-resistant container were maintained at the predetermined foaming temperature and foaming pressure for another 30 minutes. After that, by supplying carbon dioxide, while maintaining the foaming pressure in the pressure-resistant container at a predetermined foaming pressure, the dispersion liquid is discharged under atmospheric pressure through a 3 mmφ diameter orifice provided at the bottom of the pressure-resistant container, and is polypropylene-based. One-stage foamed particles of resin were obtained. Then, the one-step foamed particles of the polypropylene resin were dried at 75 ° C. for 24 hours. Here, in Comparative Examples 4 to 6, after producing the one-stage foamed particles, the one-stage foamed particles were washed by spraying water on the obtained one-stage foamed particles. This cleaning is for removing the tricalcium phosphate adhering to the surface of the polypropylene-based resin foamed particles.

Further, with respect to Examples, Comparative Examples and Reference Examples (excluding Example 20) in which the one-stage foamed particles were obtained, the two-stage foamed particles of the polypropylene-based resin were sequentially subjected to the methods (1) to (4) below. (1) Each of the obtained one-stage foamed particles was supplied to a 1 m ³ pressure-resistant container; (2) the supplied one-stage foamed particles were subjected to the internal pressure shown in Table 1 by air pressurization. (3) Then, the one-stage foamed particles were transferred to a two-stage foaming machine; (4) Then, the particles were further heated by steam having the heating vapor pressure shown in Table 1 and further foamed to obtain two-stage foamed particles.

[Manufacturing of foam molded article (plate-shaped) in polypropylene resin mold] (for evaluation of fusion property, equipment corrosiveness, and mold contamination property)
Next, using the two-stage foamed particles of the polypropylene-based resin (Examples 1 to 19, Comparative Examples 1 to 7, 9 to 11, 15, 16 and Reference Examples 1 to 7), or one-stage of the polypropylene-based resin. Using the foamed particles (Example 20), a plate-shaped polypropylene-based resin mold in-foamed molded product was produced by the following method. (I) The two-stage foamed particles or the one-stage foamed particles were subjected to an internal pressure of 0.20 MPa, and then filled in a mold having a length of 400 mm, a width of 300 mm, and a thickness of 50 mm. Here, as the filling method, the method (A) described above was adopted, the cracking amount was set to 5 mm except for Reference Example 7, and the cracking amount was set to 2 mm for Reference Example 7. (Ii) After filling, the two-stage foamed particles or the one-stage foamed particles were heated with steam of 0.32 MPa (gauge pressure). (Iii) A polypropylene-based resin in-mold foam molded product was obtained by fusing the two-stage foamed particles or the one-stage foamed particles to each other by the heating. (Iv) The obtained polypropylene-based resin in-mold foam molded product was taken out from the mold. The above (i) to (iv) were continuously performed in 1000 shots (1000 times).

[Preparation of foamed molded product (box shape) in polypropylene resin mold] (for evaluation of deformation amount after molding)
Next, using the two-stage foamed particles of the polypropylene-based resin (Examples 1 to 19, Comparative Examples 1 to 7, 9 to 11, 15, 16 and Reference Examples 1 to 7), or one stage of the polypropylene-based resin. Using the foamed particles (Example 20), a box-shaped polypropylene-based resin mold in-foamed molded product was produced by the following method. (I) After applying an internal pressure of 0.20 MPa to the two-stage foamed particles or the one-stage foamed particles, the box-shaped polypropylene-based resin mold in-foamed molded product shown in FIGS. 2 and 3 was filled in a mold capable of providing the foamed molded product. .. Here, the design external dimensions of the polypropylene-based resin mold in-foam molded product were c × d × e = 353 mm × 327 mm × 180 mm, f = 135 mm, g = 122 mm, and h = 70 mm. Further, the dimensions of the protruding portion (protruding portion 2 in FIG. 2) of the polypropylene-based resin mold in-foam molded body were set to length in the x direction × length in the y direction × length in the z direction = 5 mm × 103 mm × 153 mm. ..

In Examples 1 to 20, polypropylene-based resin foamed particles were produced by the method for producing polypropylene-based resin foamed particles according to the embodiment of the present invention. Specifically, (a) a foaming agent containing carbon dioxide is used, (b) a dispersion liquid within a specific pH range and containing a specific dispersant is used, and (c) an aliphatic diethanolamine. A specific amount of fatty acid ester and / or fatty acid diethanolamine was used with respect to 100 parts by weight of the polypropylene resin. As a result, (a) polypropylene-based resin foamed particles can be obtained in a state where the dispersion of polypropylene-based resin particles in the dispersion liquid in the pressure-resistant container is stable, (b) equipment corrosion does not occur, and (c) Furthermore, it can be seen that mold contamination did not occur after in-mold foam molding using the obtained polypropylene-based resin foam particles. Further, in Examples 1 to 20, aliphatic diethanolamine fatty acid ester and / or fatty acid diethanolamine is used. As a result, it can be seen that in the finally obtained polypropylene-based resin mold in-foamed molded product, the deformation immediately after molding is suppressed, in other words, the deformation immediately after molding is suppressed well.

In Comparative Examples 1 to 3, the aliphatic diethanolamine fatty acid ester and / or the fatty acid diethanolamine is not used. As a result, when the pH of the dispersion liquid is within the range where equipment corrosion does not occur (that is, near neutrality), the dispersed state of the polypropylene-based resin particles in the dispersion liquid is unstable when the polypropylene-based resin foamed particles are produced. It turns out that it becomes. Further, in Comparative Examples 1 to 3, the aliphatic diethanolamine fatty acid ester and the fatty acid diethanolamine are not used. As a result, it can be seen that in the finally obtained polypropylene-based resin mold in-foamed molded product, the deformation immediately after molding is remarkable.

In Comparative Examples 4 to 7, tricalcium phosphate was used as the dispersant without using kaolin as a silicate. As a result, regardless of the presence or absence of the aliphatic diethanolamine fatty acid ester and the fatty acid diethanolamine, (a) polypropylene-based resin foaming in a dispersion liquid having a pH within a range in which equipment corrosion does not occur in a state where the dispersion of polypropylene-based resin particles is stable. It is possible to obtain particles, but it can be seen that (b) mold contamination occurs. Further, in (a) Comparative Examples 4 to 6 in which the one-stage foamed particles were washed as described above, the finally obtained polypropylene-based resin mold in-foamed molded product had good fusion properties, but (b). ) In Comparative Example 7 in which the one-stage foamed particles were not washed, it can be seen that the finally obtained polypropylene-based resin mold in-foamed molded product had poor fusion properties. Further, in Comparative Examples 5 and 6 in which the aliphatic diethanolamine fatty acid ester and the fatty acid diethanolamine are used, it can be seen that the finally obtained polypropylene-based resin mold in-foamed molded product suppresses the deformation immediately after molding. .. On the other hand, in Comparative Example 4 in which the aliphatic diethanolamine fatty acid ester and the fatty acid diethanolamine were not used, and Comparative Example 7 in which the one-stage foamed particles were not washed, the finally obtained polypropylene-based in-mold foam molded product was used. It can be seen that the deformation immediately after molding is remarkable.

In Comparative Example 8, the total amount of the aliphatic diethanolamine fatty acid ester and the fatty acid diethanolamine used exceeds the range specified by this production method. As a result, it can be seen that in the production of polypropylene-based resin particles, the extrusion of the melt-kneaded product containing the polypropylene-based resin composition becomes unstable and it is difficult to obtain polypropylene-based resin particles.

In Comparative Examples 9 to 11, the total amount of the aliphatic diethanolamine fatty acid ester and the fatty acid diethanolamine used is smaller than the range specified in this production method. As a result, (a) the dispersed state of the polypropylene-based resin particles in the dispersion liquid becomes unstable, and (b) the finally obtained polypropylene-based resin in-mold foam molded body is significantly deformed immediately after molding. It turns out that.

In Comparative Examples 12 to 14, the amount of silicate (specifically, kaolin) used is less than the range specified in this production method. As a result, it can be seen that the dispersed state of the polypropylene-based resin particles in the dispersion liquid is significantly deteriorated. As a result, lumps of polypropylene-based resin particles remained in the pressure-resistant container, and polypropylene-based resin foamed particles could not be produced.

In Comparative Example 15, a hindered amine compound is used without using an aliphatic diethanolamine fatty acid ester and a fatty acid diethanolamine. As a result, it can be seen that in the finally obtained polypropylene-based resin mold in-foamed molded product, the deformation immediately after molding is remarkable.

In Comparative Example 16, (a) the aliphatic diethanolamine fatty acid ester and the fatty acid diethanolamine were not used, and (b) the two-stage foamed particles and the finally obtained polypropylene-based resin mold in-foamed molded product appeared. The density exceeds the above-mentioned preferable range of values. As a result, it can be seen that in the finally obtained polypropylene-based resin mold in-foamed molded product, deformation immediately after molding is suppressed.

In Reference Examples 1 and 2, the pH of the dispersion is adjusted to deviate from the range specified in this production method to the acidic side. As a result, (a) polypropylene-based resin foamed particles are obtained in a state where the dispersion of the polypropylene-based resin foamed particles in the dispersion liquid in the pressure-resistant container is stable without using the aliphatic diethanolamine fatty acid ester and / or the fatty acid diethanolamine. It is possible, but (b) it can be seen that the equipment corrosiveness is poor. Further, in Reference Examples 1 and 2, the aliphatic diethanolamine fatty acid ester and / or the fatty acid diethanolamine is not used. As a result, it can be seen that in the finally obtained polypropylene-based resin mold in-foamed molded product, the deformation immediately after molding is remarkable.

In Reference Examples 3 to 5, silicate, aliphatic diethanolamine fatty acid ester and fatty acid diethanolamine are used. As a result, the obtained polypropylene-based resin foam particles and the obtained polypropylene-based resin in-mold foam molded article are within the scope of one embodiment of the present invention. However, in Reference Examples 3 to 5, the amount of silicate (specifically, kaolin) used exceeds the range specified by this production method. Therefore, in the obtained polypropylene-based resin foamed particles, the amount of silicate adhering to the surface of the polypropylene-based resin foamed particles exceeds the above-mentioned preferable range value. As a result, it can be seen that in the finally obtained polypropylene-based resin mold in-foamed molded product, (a) the fusion property is poor and (b) the deformation immediately after molding is remarkable.

In Reference Example 6, the total amount of the aliphatic diethanolamine fatty acid ester and the fatty acid diethanolamine used is within the range specified by this production method. As a result, (a) the dispersion of the polypropylene-based resin particles in the dispersion liquid is stable, and (b) the obtained polypropylene-based resin foamed particles and the obtained polypropylene-based resin in-mold foamed molded product are of the present invention. It can be seen that the deformation is suppressed immediately after molding in (c) the finally obtained polypropylene-based resin mold in-foamed molded product, which is within the range of one embodiment. However, in Reference Example 6, the pH of the dispersion is out of the range specified by this production method on the acidic side. As a result, it can be seen that the equipment corrosiveness is poor.

In Reference Example 7, the total amount of the aliphatic diethanolamine fatty acid ester and the fatty acid diethanolamine used is within the range specified by this production method. As a result, the obtained polypropylene-based resin foamed particles are within the scope of one embodiment of the present invention. However, in Reference Example 7, when in-mold foam molding is performed using the obtained polypropylene-based resin foamed particles, the amount of cracking during in-mold foam molding is set to 2 mm, and the appearance is outside the scope of one embodiment of the present invention. A polypropylene-based resin mold in-foam molded article having a density was produced. As a result, the finally obtained polypropylene-based resin mold in-foamed molded product has a total content of the aliphatic diethanolamine fatty acid ester and the fatty acid diethanolamine within the range of one embodiment of the present invention, but is deformed immediately after molding. It turns out to be remarkable.

Materials and compounding amounts (addition amounts) used in Examples 1 to 20, Comparative Examples 1 to 16, and Reference Examples 1 to 7, and Examples 1 to 20, Comparative Examples 1 to 16, and Reference Examples 1 to 7. The evaluation results of each of the above are shown in Tables 1 to 6.

According to one embodiment of the present invention, there is provided a method for producing polypropylene-based resin foamed particles, which can efficiently obtain polypropylene-based resin foamed particles that can provide a polypropylene-based resin-molded in-foamed molded article having excellent quality. can do. Therefore, the method for producing polypropylene-based resin foam particles according to an embodiment of the present invention is applied to packaging materials, cushioning materials, heat insulating materials, building materials, etc., particularly to cushioning packaging materials for electronic parts such as OA equipment and mechanical parts. , Can be suitably used.

1 Polypropylene resin mold in-foam molded body 2 Protruding part

Claims (9)

A method for producing polypropylene-based resin foamed particles using a dispersion liquid containing polypropylene-based resin particles, water, and silicate, and an inorganic foaming agent containing carbon dioxide.
(A) The polypropylene-based resin particles are made of a polypropylene-based resin composition.
(B) The polypropylene-based resin composition contains an aliphatic diethanolamine fatty acid ester and / or an aliphatic diethanolamine in a total amount of 0.2 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the polypropylene-based resin.
(C) The dispersion liquid contains (a) 25 parts by weight or more and 100 parts by weight or less of the polypropylene-based resin particles with respect to 100 parts by weight of water, and (b) 0.05 parts by weight or more of the silicate. Including 0.25 parts by weight or less,
(D) A method for producing polypropylene-based resin foamed particles, wherein the pH of the dispersion is 5 or more and 9 or less. Claim 1 is characterized in that the aliphatic diethanolamine fatty acid ester is a compound represented by the following general formula (1), and the aliphatic diethanolamine is a compound represented by the following general formula (2). The method for producing the polypropylene-based resin foamed particles according to the above.

(R ¹ represents an alkyl group having 12 to 24 carbon atoms, R ² represents an alkyl group having 11 to 23 carbon atoms, and R ¹ and R ² may be the same or different).

(R ³ indicates an alkyl group having 12 to 24 carbon atoms) The production of the polypropylene-based resin foamed particles according to claim 1 or 2, wherein the aliphatic diethanolamine fatty acid ester is stearyl diethanolamine monostearic acid ester, and the aliphatic diethanolamine is stearyl diethanolamine. Method. Polypropylene resin foam particles,
Containing polypropylene-based resins, silicates, and aliphatic diethanolamine fatty acid esters and / or aliphatic diethanolamine,
The total content of the aliphatic diethanolamine fatty acid ester and / or the aliphatic diethanolamine is 0.2 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the polypropylene-based resin.
Polypropylene-based resin foamed particles, characterized in that the silicate is adhered to the surface of the polypropylene-based resin foamed particles. The fourth aspect of claim 4, wherein the aliphatic diethanolamine fatty acid ester and the aliphatic diethanolamine are contained in a total amount of 0.2 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the polypropylene-based resin. Polypropylene resin foam particles. The polypropylene-based resin foamed particles according to claim 4 or 5, wherein the silicate is kaolin. Claims 4 to 6, wherein the amount of the silicate adhered to the surface of the polypropylene-based resin foamed particles is 200 ppm or more and 2000 ppm or less with respect to the weight of the polypropylene-based resin foamed particles. The polypropylene-based resin foamed particles according to any one of the items. The first aspect of any one of claims 4 to 7, wherein the apparent density of the polypropylene-based resin foamed particles is 15 g / L or more and 29 g / L or less, and the open cell ratio is 0% to 10%. The polypropylene-based resin foamed particles described in. A polypropylene-based resin in-mold foam molded product obtained by in-mold foam molding of the polypropylene-based resin foamed particles according to any one of claims 4 to 8.
A polypropylene-based resin mold in-foamed molded article having an apparent density of 17 g / L or more and 33 g / L or less.

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