JPH04118224A - Manufacture of polyolefin-based resin in-mold formed body and polyolefin-based resin in-mold formed body - Google Patents

Abstract

PURPOSE:To make it possible to expand and fuse foaming articles, onto the surface of each of which modifying material is strongly adhered, together in a mold by a method wherein fine polyolefin-based adherent resin powder is added to polyolefin-based resin foaming particles and mixed under heat so as to prepare adherent resin, in the surface of which modifying material is included, in order to be scattered, fused and fixed under the condition being in-mold heated with steam having the specified temperature. CONSTITUTION:Foaming particles, onto the surface of each of which modifying material made of fine inorganic or organic powder is fixed, are charged in a mold and heated so as to be expanded and fused to one another in order to produce a formed body. In order to fixe the modifying material to the surface of the foaming particle, fine polyolefin-based adherent resin powder is added to polyolefin-based resin foaming particles, which are heated through mixing with high shearing force and the temperature of which is controlled, so as to mix under heat in order to dispersedly fuse said adherent resin onto the surface of the foaming particle. After that, fine modifying material powder is fed from above to the resultant foaming particles and mixed under heat so as to scatteringly fix modifying material- contained adherent resin onto the surface of the foaming particles. In-mold heating is performed by steam having the temperature ranging from the one, which is higher than the melting point of the foaming particle by 2 deg.C, to the one, which is higher than said melting point by 14 deg.C.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is directed to the production of polyolefin resin in-mold molded articles using expanded particles in which a modifier, which is an inorganic or organic fine powder, is fixed on the surface of the particles. The present invention relates to a method and improvement of an in-mold molded product thereof, and specifically relates to a technology for improving an in-mold molded product useful in the fields of conductive cushioning packaging materials, flame-retardant cushioning interior materials, and the like.

"Prior Art" First, a method for producing an in-mold molded article using expanded polyolefin resin particles is disclosed in, for example, Japanese Patent Publication No. 51-22951 and Japanese Patent Publication No. 53-33995.

In short, this method involves foaming a polyolefin resin to form foamed particles, imparting expansion ability (the ability to expand in volume when heated inside the mold), filling the mold, and then heating the inside of the mold to form foamed particles. This is a method of expanding and fusing the materials into a molded product. In addition, the in-mold molded product obtained by this method is admired for its properties such as flexibility, toughness, elasticity, heat insulation, etc., which the foam itself has, and is suitable for use in cushioning containers, insulation containers, 1M impact protection equipment, etc. It is widely used.

Therefore, if the foamed particles used in this molded body are modified (for example, modified to have electrical conductivity, flame retardancy, cosmetic properties, etc.), a molded body with the desired shape can be obtained, for example, with conductivity, flame retardancy, and cosmetic properties. Everyone thinks that it is very convenient because it can be obtained in a cosmetically beautiful state. In short, what is added to the particles is
The difference is whether it is a conductive fine powder such as carbon or metal, a flame retardant fine powder, or a general pigment fine powder.

However, at present, there is no such improved in-mold molded product of polyolefin resin of a level that can be put to practical use.

The actual situation will be explained in detail below by exemplifying the case of imparting conductivity, which is considered to be the most difficult to realize.

First, the general method of applying this type of fine powder modifier to resin particles is to foam the particles with the fine powder modifier kneaded into the resin, and then mold the foamed particles into a molded product in a mold. This is the way to do it. The problem with this method is that the amount of conductive carbon black that is considered to exhibit conductivity when molded is 5% by weight or more, preferably 1% by weight.
Although it can reach more than 0% by weight, this addition amount significantly deteriorates the cell structure that makes up the particles when they are made into foamed particles, and when these are subjected to molding, there may be poor adhesion between the particles or the appearance quality may deteriorate. This is a problem that only results in a chipped molded body.

As an alternative technique, there is a technique in which a fine modifier powder is fixed on the surface of particles. Specifically, for example, i) JP-A-59-169199, if) JP-A-53-1
Publication No. 25537, 1ii) JP-A-63-275648
iv) JP-A-58-92540, JP-A-60-195134, and the like.

In other words, technology i) involves attaching conductive microfibers (equivalent to fine powder) to the surface of foamed particles (polystyrene resin) using a surfactant, etc., and molding the particles in a mold to form conductive microfibers. If
) technology mixes resin particles and a modifier in a mixer with high shear force, softens the surface of the particles and fixes the modifier there, and then injects the resin particles with a foaming agent in an aqueous medium. to contain,
FIT's technology involves heating and foaming to form foamed particles, which are then subjected to in-mold molding.Fit's technology involves impregnating and fixing a modifier on the resin surface in an aqueous suspension system under high temperature and high pressure, and then adding a foaming agent to this. The specific technique of iv) is to apply an aqueous solution of a conductive substance suspended in a synthetic resin emulsion to the surface of the foamed particles. They each proposed a method of drying and solidifying the foamed particles and subjecting the foamed particles to in-mold molding. However, according to the experiments of the present inventors, the above i), if), 1
The in-mold molded bodies obtained by the methods described in ii) and iv) are of a quality level that can be put to practical use. The reality is that first of all, if the level of conductivity (antistatic properties) obtained is too low, or the conductive substance is poorly fixed, it may fall off or
The problem is that the transmutation phenomenon is significant and that the conductivity cannot be maintained sustainably.In order to improve this problem, increasing the fixation amount of the modifier causes fusion between the foamed particles when molded. The condition deteriorates, and the problem arises that the mechanical properties of the molded product cannot be ensured. Considering the above phenomenon based on the knowledge of the inventors, even if it is assumed that the technique i) is applicable to polystyrene resin, in the case of polyolefin resin, which cannot be expected to have a swelling effect on surfactants etc. , the degree of fixation of the modifier on the surface of the foamed particles is low, and most of the modifier that should have been fixed on the surface of the foamed particles during the floating conveyance process by the pressurized gas used during particle transport and filling. This causes a phenomenon in which the particles fall off and dissipate. Furthermore, methods ii) and 1ii) suffer from the same phenomenon as described above, in which the modifier fixed on the particle surface falls off during the step of impregnating the particle with a blowing agent. The description in the publication states that it is possible to attach a large amount of conductive material and that the fusion between foamed particles is good when formed into a molded product, but additional tests by the present inventors have shown that manufacturing In the process, there are problems such as significant contamination of mixer walls and mold walls due to adhesion of resin emulsion containing conductive substances, problems that drying time of foamed particles after adhesion treatment is long, and particles becoming agglomerated with each other during drying. Stirring to prevent this has the problem of accelerating the detachment of the adhesion layer. The adhesive layer still often falls off in the resulting molded product, and it is difficult to guarantee the sustainability of the modification effect in a state where it can spread and contaminate objects that come in contact with it, such as hands and clothes. In addition, a problem has been observed in which the strength of the fusion bond between the particles forming the molded body is such that if the molded body is bent, the fusion bond between the particles will break. This phenomenon is caused by the basic problem that the resin film formed in the emulsion is brittle and has poor adhesion to the surface of the polyolefin resin particles. It is inferred that this is due to the fundamental problem that the amount of resin that can be adhered and solidified to the surface is too small to include and adhere a conductive substance.

In addition, in any method, if water, lubricant, or surfactant remains on the surface of the foamed particles, there is a tendency to deteriorate the fusion state between the foamed particles when polyolefin resin is used. strong.

[Problems to be solved by the invention] The present invention was finally completed as a result of long-term research in view of solving the above-mentioned current problems, and its main point is to modify adhesive resin in the form of fine powder. This is used as a fixing medium for the material, but ultimately small pieces of adhesive resin containing fine powder of the modifier are dispersed and developed in a film on the surface of the foamed particles through the adhesive resin. The present invention has completed foamed particles that are dispersed and fixed on the surface of the particles and is then subjected to molding, thereby solving all of the problems of the prior art described above.

In this sense, the purpose of the present invention is to provide an in-mold molded product of polyolefin resin that is made of foamed particles with fine modifier powder fixed to the surface thereof, and the modification effect thereof is extremely high ( For example, the surface resistance value is I x 10
In practice, the adhesion of the modifying material fixed on the surface is extremely strong, maintains the sustainability of its modification effect, and maintains the fusion properties and appearance quality of the molded product. For the first time, we are providing an in-mold molded body that maintains the structural strength and cushioning properties for conductive buffer containers, conductive durable buffer returnable boxes, flame-retardant heat-insulating buffer interior materials, etc. Furthermore, another object of the present invention is to provide a method for producing a molded body of this kind that can be made into a desired shape and stably supplied at low cost without contaminating machine walls or mold walls.

[Means for solving the eight problems] The object of the present invention is to provide a method for manufacturing an in-mold molded article of the present invention,
In other words, ``polyolefin-based polyolefin-based molded products are made by filling foamed particles with a modifier, which is a fine inorganic or organic powder, fixed on the surface of the particles, into a mold and heating them to expand and fuse the foamed particles to each other. In the method for producing an in-mold resin molded article, ■ a method for fixing a modifying material on the surface of the expanded particles;
Under high shear mixing, polyolefin adhesive resin fine powder is supplied to temperature-controlled polyolefin resin foam particles, heated and mixed to disperse and fuse the adhesive resin onto the surface of the foam particles, and then The method is such that the adhesive resin containing the modifier is dispersed and fixed on the surface of the foamed particles by supplying the modifier powder and heating and mixing. ``A method for producing an in-mold molded article using polyolefin resin foam particles,'' characterized by steam heating at a temperature in the range of 2° C. above the melting point of 14° C. to 14° C. above the melting point. In an in-mold molded body made of polyolefin resin foam particles in which a modifier is fixed on the surface of the particles, the modifier is finely powdered carbon black, and its content is 3% relative to the amount of resin. At a value of ~0.1% by weight, the fixation of a polyolefin adhesive resin containing carbon black in a molded article was 1 in a peel test using an adhesive tape.
It is in a strong fixing state with a low value of 0% or less, and the surface resistance value of the molded product is 1xlO'Ω to lXl013Ω.
A polyolefin resin in-mold molded article characterized by being in the range of. ” and “In an in-mold molded body made of polyolefin resin foam particles in which a modifier, which is a fine inorganic or organic powder, is fixed on the surface of the particles, the modifier is a fine powder flame retardant, and the modifier is a fine powder flame retardant. The content is 5 to 0.1% by weight based on the amount of resin, and the fixation of the polyolefin adhesive resin containing flame retardant in the molded product is as low as 10% or less in a peel test using adhesive tape. The molded product has a strong fixation state, and the fusion property between the foamed particles constituting the molded product shows a value of 80% or more, and the compression set at 25% compression as a molded product is less than 6%. "An in-mold polyolefin resin molded product characterized by having a high value." In the molded article, the modifier is a coloring pigment, the content of which is 5 to 0.1% by weight based on the amount of resin, and is used to fix the polyolefin adhesive resin containing the pigment in the molded article. is in a strong fixed state, showing a low value of 10% or less in a peel test using an adhesive tape, and the fusion property between the foamed particles constituting the molded product is 80% or more, and the molded product has a low value of 10% or less in a peel test. This can be easily achieved by employing a polyolefin resin in-mold molded article characterized in that the compression set at 25% compression measured as follows is less than 6%.

[Action Co. The contents of the present invention will be explained below using drawings, tables, etc.

FIGS. 1 and 2 are micrographs (approximately 1
Figures 3 and 4 are experimental results diagrams illustrating the adhesion state of the modifier (carbon black) at a magnification of 50 times). It is an experimental diagram showing the performance (features) of foamed particles to which a modifying material is fixed, which led to the completion of the process.

Therefore, the following description is the features of the manufacturing method of the present invention,
This is also a feature of the expanded particles used in the molding of the present invention, and at the same time, it is also a feature of the molded product that is completed thereby.

First, in FIG. 3, the vertical axis shows the level of conductivity (surface resistance value Ω of the compact) [the smaller the value, the better the conductivity], and the horizontal axis shows the carbon black content. The content of this carbon black (modifying material) is the amount that is fixed and contained in the foamed particles used in this experiment, and also corresponds to the content of the completed molded body, and the level of conductivity was perfected. This is the actual measured value of the surface resistance of the molded body. And the graph! ■ is,
The kneaded product (comparative amount), graphs I and II are those of the fixed amount (product of the present invention) as referred to in the present invention.

According to the results in Figure 3, the comparative amount of kneading is
The conductivity obtained by increasing the amount of carbon black hardly changes and remains at a conductivity level where no modification effect is observed. the level of quality effect is increased and its content is at least 1012Ω at 0.1% by weight;
It has been shown that when the content is 3% by weight, a modification effect of 104Ω level is exhibited.

The results shown in FIG. 3 indicate that the foamed particles employed in the present invention have the feature of being able to practically fix a large amount of carbon black, up to 3% by weight, on their surfaces. When it becomes a molded product, it has a level of 104Ω with a small amount of carbon black, only 3% by weight.
The characteristics of the conductive modification effect have been demonstrated. A molded body with such a conductive effect is an in-mold molded body of a polyolefin resin, which is made of foamed particles with a modifier fixed to the surface of the particles using the heat-fusibility of the polyolefin adhesive resin. However, this has not been realized in the past and has been completed for the first time by the present invention.

Accordingly, the statements in claims 2 to 4 of this specification express the novel molded body shown in FIG. 3.

In the next y, Figure 4, the vertical axis is the same conductivity level (Ω) as in Figure 3.
), and the horizontal axis is the expansion ratio (cc/g) of the molded product (approximately the same as the foamed particles used). However, what should be noted here is that the two graphs ■ and ■ shown here are foamed particles obtained by re-expanding and increasing the expansion ratio with the modifying material fixed on the surface. It is a plot of the foaming ratio of the molded body and the surface resistance value exhibited by the molded body at the time.

The results shown in FIG. 4 most clearly show the greatest feature (firmness of the fixed state) of the surface state of the expanded particles used in the present invention. In other words, even if the foaming ratio of the particles is increased and the distance between the modifiers is widened, the modification effect is only slightly reduced by the modifiers that are fixed to the surface. It can be said that there is almost no decrease phenomenon with particles. The feature of this foamed particle is that it fully follows the volume expansion of the particle caused by heating in the mold, which is the basis for exhibiting a high level of reforming effect, and furthermore, the expansion ratio (density) can be changed over a wide range. This proves that this is the basis for freely obtaining in-mold compacts with a high level of modification effect.

Table 2 below shows the results of an experiment showing the adhesion strength of the modifying material on the surface condition of the foamed particles used in the present invention. This confirms the extent to which the modification effect (level of conductivity) decreases when repeatedly transported.

According to the results in Table 2, even after repeated conveyance 20 times, the modification effect (level of conductivity) exhibited by the molded product hardly changed, and the modification effect (level of conductivity) of the molded product did not change much. The fixation has proven to be extremely strong. This strong adhesion, combined with the abrasion of the surface of the foamed particles before it becomes a molded object, produces a molded object with a high level of modification effect, and the molded object has a sustained modification effect during practical use. This is the root cause of the person's performance.

The surface condition of the molded article of the present invention shown in FIGS. 1 and 2 is different from that of the two types of expanded particles subjected to the molding process, that is, the fixation state of the modifier is slightly different between the two types of expanded particles. Due to the difference,
Figure 2 shows the result of an experiment using foamed particles in which small pieces of adhesive resin containing a modifier were fused and fixed to the surface of the foamed particles via an adhesive resin film fused to the surface of the foamed particles. NO3
The surface condition of the molded product No. 2 is illustrated as a representative example of these.

On the other hand, Fig. 1 shows the case in which the foamed particles described in Fig. 2 above were further fixed and reinforced on the surface with an adhesive resin film, and the molded product of Experiment No. 091 was used. The surface conditions of are shown as representative examples of these.

The difference between Fig. 1 and Fig. 2 is the way in which the small pieces of adhesive resin containing the modifier (the part that looks black) are dispersed and developed.
The surface of the foamed particles in Fig. 1 has mesh-like portions, and in Fig. 2 it is mainly dotted, showing how they are dispersed and expanded.

The difference in the state of dispersion and development lies in the behavior of the "adhesive resin containing the modifier" part that is fixed to the surface when the foamed particles expand, and the one in Figure 1 is stretched. It is inferred that the elements were expanded in a mesh pattern because the elements were large, and the one in Figure 2 was expanded in a scattered pattern because the elements to be expanded were small. The characteristics of both of these are that the mesh-like one shown in Figure 1 has a high probability of being joined at one of the surface parts of each particle that makes up the compact, and that the joints are difficult to break. Compared to a molded body with a high quality effect, which exhibits its reforming effect without lowering its level even when the expansion ratio is increased, the dotted shape shown in Figure 2 has a low probability of being joined and is It is presumed that because the portions are easily cut, the level of the modification effect of the obtained molded product is somewhat low, and that the level of the modification effect is likely to decrease as the expansion ratio increases.

Therefore, both of the conditions shown in FIGS. 1 and 2 are representative of the "surface-fixed state" of the present invention, but from the viewpoint of expecting a high level of modification effect, the state shown in FIG. 1 is more desirable.

Furthermore, Table 3 shows that even if the foamed particles used in the present invention have a modifier adhered to their surface, the expandability, melt flowability, fusibility, etc. of the foamed particles do not deteriorate due to this. Therefore, when it is subjected to in-mold molding, it has "fusibility"
This shows that it is possible to obtain a molded product that satisfies practical properties such as "appearance quality,""compressionset," and "repeated compression set." In particular, the "adhesion state of modified material" based on a peel test using adhesive tape is a quantification of the state of adhesion of the adhesive resin containing the modifier to the surface of the molded object after it has been formed into a molded object. This evaluation is strong and excellent (10
%) is also a substitute property that indicates that the sustainability of the modification effect (for example, the abrasion resistance, water washing resistance, and humidity resistance evaluated in the present invention) is ensured. ,
The molded article of the present invention is also a structural indicator indicating that it is composed of expanded particles in which a polyolefin adhesive resin containing a modifier is fixed by heat fusion to the surface of the particles. For example, even if a resin layer formed from an aqueous emulsion is made of a polyolefin resin, the "fixing state of the modified material" evaluated in the above peel test may be 20% at best. This is based on the fact that it is possible for the rate to fall below 10%, but it is impossible for it to fall to a level as low as 10%. The target samples in Table 3 are:
The ones in Category A group are exactly like the graph ■ in Figure 4.

These are the evaluation values of the molded bodies shown in (2), and those in the category B group are those in which the modifying material (carbon black) in the A group was changed to a flame retardant.

The results in Table 3 show that the molded product of the present invention has practical properties as a molded product even if it contains as much as 3% by weight of the modifier. It has been confirmed that the flame retardant-containing molded bodies shown in Table 3 all exhibit excellent flame retardant modification effects. Item 3.4 of the claims of the present invention is expressed based on the results of Table 3 with some observations added thereto.

The constituent features of the invention of the "method for producing an in-mold molded article" of the present invention are explained below in Table 1.

The main part of the invention in the manufacturing method of the present invention is the part described in (■■) of the above claim 1, that is, (1) the method for fixing the modifying material on the surface of the expanded particles,
Under high shear mixing, polyolefin adhesive resin fine powder is supplied to temperature-controlled polyolefin resin foam particles, heated and mixed to disperse and fuse the adhesive resin onto the surface of the foam particles, and then The method is a method in which the modified fine powder is supplied to the foamed particles, and the adhesive resin containing the modifier is dispersed and fixed on the surface of the foamed particles by heating and mixing. The steam heating is carried out at a temperature in the range from 2°C above the melting point to 14°C above the melting point.

First of all, the importance of the part ■ is summarized in Figures 3, 4 and 2.
The purpose is to obtain expanded particles useful in the present invention, as detailed in the table.

In other words, ``a process in which small pieces of adhesive resin containing modified fine powder are dispersed and fixed on the surface of the foamed particles via the adhesive resin that is dispersed and developed in the form of a film on the surface of the foamed particles. This is to complete the "foamed particles", and the first half of the above (■) is to ensure that the supplied adhesive resin fine powder is uniformly dispersed on the surface of the foamed particles without waste, and is sprinkled and fused. This process involves forming an adhesive resin film on the surface of the expanded particles. Then, in the second half of the following part (■), the supplied modified fine powder is entangled with the excess adhesive resin on the surface of the foamed particles and is sprinkled with each other, reducing the fluidity of the adhesive resin and modifying it. This is a step in which small pieces of adhesive resin are formed containing fine powder, and the small pieces are firmly fused to the surface of the foamed particles via the adhesive resin film remaining on the surface of the particles.

This process (■) uses heat-sensitive foamed particles as a base material and heats and mixes them. Therefore, the local heat generation and forced stirring force generated by the high-shear mixer, and the instantaneous melting caused by the fine powder adhesive resin. This technique was perfected by skillfully utilizing the characteristics and appropriateness of the mixing order.

Therefore, for example, when supplying each fine powder of an adhesive resin or a modifier, it is preferable to supply the powder in small amounts step by step several times over time.

Then, when the adhesive resin containing the modified fine powder becomes small pieces and is dispersed and fixed to cover the entire foamed particles, the wall of the mixer is cooled, and stirring is continued at a low rotation speed. It is desirable to cool the surface temperature of the expanded particles to a low temperature below the melting point of the adhesive resin, and to fuse and solidify the dispersed and fixed adhesive resin pieces. In this way, almost all of the supplied adhesive resin and modifier will be fused to the surface of the particles, and there will be no possibility of contamination by adhering to the wall surface or rotating body surface of the mixer. There is no loss of adhesive resin or modifier, and there is also the advantage that the quality of the particles obtained can be adjusted by controlling the supply amount itself.

The fact that the object of the present invention cannot be achieved with another mixing method different from the above (■) is summarized in Table 1 and detailed in the corresponding Example/Comparative Example 1. Explain useful mixing conditions to make the process more complete.

The heating and mixing conditions for perfecting the above item (1) are as follows: The surface temperature of the foamed particles during agitation and flow in the mixing tank ranges from the melting point of the foamed particles minus 2°C to the melting point of the target adhesive resin plus 2°C (however, the melting point of the foamed particles The temperature is in the range -2°C>melting point of the adhesive resin +2°C), and the mixing speed is a high-speed flow (under high shear force) at a circumferential speed of Ion/see or higher.

This condition is in order to soften the surface of the expanded particles, which are sensitive to temperature, etc., to fuse the adhesive resin fine powder to the particles, and to fluidize and disperse the molten adhesive resin to fix it on almost the entire surface of the particles. This technique utilizes the shear and frictional heat generated between the foam particle surface and the mixing rotor blade. The mixer to be used is a high-speed mixer commercially available under trade names such as Henschel mixer and Spar mixer, and the machine wall is kept at a temperature below the melting point of the adhesive resin (however, the temperature of the foamed particles inside the machine can be maintained). Cool and adjust the temperature to a certain temperature. This temperature control has the effect of preferentially adhering the adhesive resin to the foamed particles.

Particularly important in step ① above is the step of entangling the foamed particles in the first half with the adhesive resin. It is to bring them into contact with. For this purpose, it is desirable to adopt mixing conditions on the high temperature side, but at high temperatures the foamed particles contract significantly, and when the melting point is reached, the structure of the foamed particles will be destroyed.

Therefore, the surface temperature of the foamed particles is the melting point of the foamed particles minus 5
Keep the temperature in the range of 11℃ to 11℃ (use adhesive resin that melts sufficiently at this temperature), and increase the peripheral speed of the mixing speed to 15 to 2℃.
The goal is to increase the speed to 5 m/sec. This is desirable because foamed particles with strong surface fusion with the adhesive resin can be obtained while shrinkage of the foamed particles is small.

In this case, it is desirable that the amount of adhesive resin is enough to cover the surface of the foamed particles used, so when dividing the amount of adhesive resin into the pre- and post-processes, at least the total amount of adhesive resin used should be One-fifth of the quantity is dispensed at this point.

Once foamed particles with an adhesive resin film that is firmly fused to the entire surface of the particles are formed in this way, the proportion of the supply form of the modifier fine powder placed on top of these particles can be freely selected. . Specifically, only the modifier or the remaining adhesive resin and the modifier are supplied simultaneously, sequentially, or alternately, or the modifier fine powder and the adhesive resin fine powder are premixed. These include supplying as a mixture, but these are all in the same category as the act of "supplying fine modifier powder" as referred to in the present invention. However, among these methods, when the small pieces of adhesive resin containing the modifier are fixed on the surface of the foamed particles, the remaining amount of adhesive resin is supplied, and the entire foamed particles are fixed and reinforced with a film-like material. As mentioned above, is desirable.

The most desirable method is to supply a premixed mixture of modifier fine powder and adhesive resin fine powder.The advantages of this method are that the subsequent mixing time is reduced to less than half, and the resulting molded product is It has the advantage of being able to further improve the modification effect (by about one order of magnitude or more in terms of conductivity effect).

The amount of adhesive resin supplied relative to the weight of the foamed particles varies depending on the expansion ratio (surface area) of the foamed particles used, but in general, the combined amount of supply before and after is 2 to 10% by weight, preferably 3 to 7% by weight of the weight of the particles. It is. In the first half, supplying one-fifth to one-third of this amount, and in the second half, supplying the remaining three-fourths to two-thirds of this amount will bring out the reforming effect more fully. preferred above.

The supply amount (equivalent to the content) of the modifier used in the present invention refers to the proportion (% by weight) of the modifier in the total amount of modified expanded particles or modified molded articles, and refers to the bulk volume. It is 0.1 to 3% by weight for carbon black, which has a large amount of carbon black, and 0.1 to 5% by weight for general pigments and flame retardants. Incidentally, this range is determined based on the amount that can be efficiently fixed on the particle surface and the amount that is effective for producing the effect. Therefore, for example, the difference in the upper limit amount between the carbon black and the general pigment is considered to be due to the difference in the surface area of the modifier.

Further, the foamed particles to be heated and mixed are preferably selected from a range of expansion ratio of 3 to 10 times. Generally, in in-mold molding, it is basic to use foamed particles with a foaming ratio close to that of the target molded object, but in the present invention, it is desired to ensure a sufficient particle surface area to adhere the required amount of modifier. ,
Foamed particles with a low expansion ratio are selected because foamed particles with a high expansion ratio tend to undergo thermal contraction and have a large amount of shrinkage.

Therefore, in the case of the present invention, the modifier is fixed and fused to foamed particles with a magnification of 4 to 6 times, and if a molded product with a high expansion ratio is required, the "foamed" Taking advantage of the property that the modification effect is unlikely to deteriorate even if the magnification of the particles is increased, it is better to use a method in which the expanded particles are subjected to molding with a higher magnification. Even more desirable. In this way, in the present invention, molded articles having a wide range of expansion ratios of 3 to 40 times can be obtained. The method and conditions for fixing the modifier to the particles described above are described for the case of foamed particles, but the method and conditions for dispersing and fixing them are almost the same even if the target is replaced with unfoamed resin particles. It can be applied. The advantage of this case is that the state of fixation of the modifier on the surface of the particles is further improved, and resin particles with a smooth surface can be obtained. This can completely prevent the modifier from falling off during the step of impregnating the foaming agent, the foaming step, etc. However, on the other hand, the phenomenon in which the modification effect decreases as the expansion ratio increases when forming expanded particles is a little harsh.
For example, if the expansion ratio exceeds 30 times, the reforming effect of the method of the present invention cannot be achieved. However, it can be used to manufacture target products with low modification effects.

Next, the necessity of component (1) (heating conditions during in-mold molding) of the above manufacturing method will be explained.

This necessity is achieved by sufficiently expanding the foamed particles in the mold, in which "small pieces of adhesive resin containing the modifier on the entire surface of the particles are fused and fixed," and firmly fused. This is a condition for

In other words, if the heating in the mold is less than the melting point of the expanded particles + 2°C, the volume expansion of the particles will be partially insufficient, resulting in gaps between the particles, or the particles will not be fused together enough to form a molded product. There is a tendency for the necessary characteristics to deteriorate as a result. On the other hand, at temperatures exceeding the melting point of the expanded particles plus 14° C., sinkage defects are likely to occur in the resulting molded product. From the viewpoint of achieving a balance between these two and obtaining a high-quality molded product, the heating temperature in the mold should range from the melting point of the expanded particles plus 3°C to the melting point plus 11°C.
It is desirable to have a temperature in the range of °C.

For heating within the mold, a contact heating method using heated steam is employed, in which steam at a desired temperature is blown into the mold and the steam comes into contact with the foamed particles filled. The reason for this is to increase thermal efficiency during heating and to promote expansion and fusion of foamed particles within the mold cavity.

The expansion ratio in the present invention is calculated by calculating the volume (Vcc) of a sample whose weight (Wg) is known by the submersion method, and dividing the volume (Vcc) by the weight (Wg) as the magnification (cc/g). This is what is shown.

The polyolefin resin that becomes the foamed particles in the present invention is a general term for resins that are generally called polyolefin resins, and among them, a foaming agent is added to the resin and foamed to form foamed particles, and the expanded particles are given expansion ability. It refers to a polyolefin resin that can be applied, filled into a mold, and heated to utilize the expansion ability to expand and fuse the particles to form a molded product with integrated foamed particles. Specifically, for example, low.

Ethylene resins represented by medium and high density polyethylene, linear low density polyethylene, linear very low density polyethylene, ethylene-vinyl acetate copolymer, etc., polypropylene, copolymer components include ethylene, butene, 1.4-2 Propylene-based resins represented by (random and block) copolymers with propylene, which is one or more types of methylpentene, mixed resins containing two or more of these resins, or mainly ethylene components. Other components include copolymerized/mixed resins containing vinyl chloride, ethyl acrylate, methyl acrylate, acrylic acid, and the like.

These resins can be used after being crosslinked before being made into foamed particles, or they can be used without crosslinking. From the viewpoint of further stabilizing the foamed state, crosslinked materials are better. Generally, this crosslinking method is a method in which a peroxide such as dicumyl peroxide is contained in a resin, the peroxide is decomposed by heating, and the resin is crosslinked.

On the other hand, the polyolefin adhesive resin referred to in the present invention is a general term for polyolefin resins that have adhesive strength to the surface of foamed particles. However, it does not include those in a state of water suspension, such as emulsion types and suspension types. The reason for this is that the object of the present invention is to be used by heat-sealing it to a resin and to take advantage of its strong and strong film quality.

Therefore, it is possible to use the same type of polyolefin resin as the foamed particles described above. Other specifics include:
Chlorinated polyolefins represented by chlorinated polyethylene and chlorinated polypropylene.

Copolymers with ethylene containing unsaturated esters such as acrylic acid esters and unsaturated acids as copolymerization components can also be used. However, in practical use, a resin with a lower melting point is selected compared to the resin used for the expanded particles, but it is also important to pay attention to selecting a resin that has excellent fluidity when melted. Desirably, the fluidity is M and I (ASTM D1238 ethylene resin: condition E, propylene resin: condition L) is 10.
Choose one in the range of g/10 minutes to 60 g/10 minutes. In addition, in order to improve the adhesion to the foamed particles, it is desirable to select a resin from among resins of the same type as the resin used to form the foamed particles.

Further, this adhesive resin is used in the form of a fine powder, specifically, in the form of a powder or scale-like fine powder with an average particle size of about 100 meshes (passes) or less. This is to ensure that it is widely dispersed throughout the foamed particles and easily melted during heating and mixing. Therefore, these materials are often prepared by specially pulverizing and classifying them, but in this case, the use of resins with low melting points, such as ethylene-vinyl acetate copolymers, is not easy to crush, so avoid using them. It's better to

The amount of adhesive resin used is approximately 2 to 10% based on the weight of the foamed particles.
% amount (ratio of adhesive resin to the total amount of resin components)
The material is selected according to the surface area of the expanded particles used and the amount of modifying material used. It is better to be careful not to use an excessive amount of the adhesive resin, as this will lead to a decrease in the expansion ratio of the resulting molded product and will also deteriorate the properties of the molded product.

The modifier used in fine powder form is selected depending on the purpose of modification.

For example, when the purpose of modification is to impart conductivity, concrete examples include fine powder of conductive substances such as graphite, carbon black, and carbon fiber, fine powder of metal such as copper and aluminum, etc. Among these, carbon black, particularly furnace carbon black with a porous structure called Ketchen black, is desirable because it can be easily fixed to the surface of foamed particles and provides high conductivity.

For example, when the purpose of modification is to impart flame retardancy, for example, brominated organic x flame retardants represented by decabromodiphenyl ether, tetrabromobisphenol A, etc., and perchloropentacyclodecane.

Chlorinated organic flame retardants such as chlorentic acid anhydride and inorganic flame retardants such as antimony trioxide are used. These are often used alone or in combination of three or more. For example, a combination of antimony trioxide and the above-mentioned brominated organic flame retardant is desirable because the flame retardant effect is greatly enhanced.

Furthermore, when the modifier is a coloring pigment, for example, organic pigments and inorganic pigments that are generally commercially available as polyolefin coloring pigments are used. These are sometimes used as processed pigments mixed with dispersants to improve dispersibility, but care must be taken as some dispersants worsen the fusion between particles during in-mold molding. It is. Therefore, in such a case, it is desirable to use a processed pigment made into fine powder using a polyolefin resin as a dispersion medium.

The evaluation method used in the present invention is shown below.

1) To evaluate the state of fusion between the foamed particles constituting the molded body in a fusion mold, a cut with a depth of 1 mm was made in the thickness direction on a molded body sample piece measuring 290 mm in length and width and 25 mm in thickness. , bend the sample piece with the cut at the top and break it in the thickness direction.

The number of expanded particles whose material has been destroyed is expressed as a percentage of the total number of particles in the fractured cross section.

(Evaluation scale) 2) Appearance quality of molded product 2)-1 Sink This evaluates the phenomenon where the molding size is insufficient in the corner of the molded product, and the diagonal of the surface of the molded product obtained is Place a ruler horizontally on both corners and measure and evaluate the maximum dimension of the gap between the corner and the surface of the molded product.

(evaluation scale) 2) - 2-particle indentation Cracks formed between foamed particles on the surface of the molded product Evaluate the degree by sight and touch.

(Evaluation scale) Hollow 3) Molded object characteristics The following two items are evaluated from the viewpoint that the molded object is a foamed particle with elastic cushioning performance.

3)-1 Compression set (%) This indicates the percentage of distortion of a molded product when a constant load is applied to the molded product over a long period of time, and is evaluated according to the JIS K6767 test method.

3)-2 Repeated compression set (%) This indicates the percentage of distortion of a molded product when a constant load is repeatedly applied to the molded product, and is evaluated according to the JIS K6767 test method.

(Evaluation scale; common to both) 4) Modification effect The modification effect is exhibited depending on the characteristics of the modifier fixed on the surface of the expanded particles.

Here, conductivity and flame retardancy are treated as representative modification effects.

4)-1 Conductive level between two electrode terminals (5 mmφ, tip 25 mm radius processed) applied to the surface of a molded body conditioned for 24 hours in a room with a temperature of 23°C and a relative humidity of 50%, with an interval of 50 mm. The resulting surface resistance value is measured with a resistance meter (applied voltage: 500 V).

The following resistance meters are used depending on the desired resistance level.

(Evaluation scale) Evaluation based on flame retardant FMVSS-302 test method (sample thickness: 5 mm) (blank below) (Evaluation scale) 5) Maintainability of conductivity 5)-1 Friction resistance Conductive performance due to friction The friction condition is to evaluate the deterioration of
kg/m3. Paste soft polyurethane with a thickness of 10 mm,
A friction element with gauze attached thereon is brought into close contact with the molded body, and a stroke length of 1 is applied under static stress of 0.1 kg/am2.
Perform 500 reciprocating frictions of 50 mm and 30 times/min.
The change in surface resistance value before and after the treatment is evaluated.

5)-2 Washing resistance This evaluates the deterioration of conductive performance due to washing with water, and the washing conditions are neutral detergent [trade name Mama Royal (manufactured by Lion Corporation)]
] using a soft urethane sponge (bulk density 25Kg/m"), the surface of the molded product was
It is washed 0 times, then washed with water, and dried for 24 hours in a constant temperature bath with air circulation at 25°C. The change in surface resistance value before and after this cleaning treatment is evaluated.

5)-3 Humidity resistance This evaluates the change in conductivity with respect to humidity.
The changes in surface resistance caused by the difference in humidity of the molded bodies that were conditioned for 24 hours at a relative humidity of 95% and 20% at °C were evaluated.

(Evaluation scale); Common to all three Ro: Value before treatment (or 95% humidity) R1: After treatment (
or 20% humidity) (blank space below) *Ro is already at a level exceeding lXl0''Ω, and there is no point in evaluating maintainability.

6) Fixed state of modified product This is an index for evaluating how firmly the adhesive resin containing the modified material remains fixed on the surface of the molded product.

That is, transparent plastic adhesive tape [Product name: Danbron Tape No. 375 (manufactured by Nitto Kogyo Co., Ltd.) width 50 mm, *
Adhesive strength measured by the following method: 230 g / 25 m
m width] is bonded to the surface of the molded article whose length is to be evaluated for a length of 5 cm or more without entrapping air, and the top is strongly pressed and rubbed through gauze. Then, on the upper surface of the tape in the densely bonded area, mark lines (5mm
cm x 5 cm), this adhesive tape is peeled off from the surface of the molded product using a tensile peel tester (peel angle 180 degrees, peel speed 30 cm/sec), and the proportion of modified substances attached to the adhesive tape is evaluated using the following evaluation scale. . Therefore, if the amount of the modified material fixed on the surface of the molded object is small and does not meet the evaluation conditions below from the beginning, or if the modified material is not a fine powder (for example, a liquid surfactant, etc.) It will not be subject to evaluation.

Evaluation conditions: Count the number of holes to which the modified substance is attached over one-third or more of the inner area of the base at 5 mm intervals, and calculate the ratio ( %) (Evaluation is performed at 5 points and the average value is used.) (Leave below) (Evaluation scale) *Measurement of adhesive strength of adhesive tape A test piece with a width of 25 mm cut from the center of the width of the adhesive tape above was used. The sample is laminated to the surface of a clean transparent glass plate over a length of 5 cm or more so as not to entrap air, and the sample is strongly pressed and rubbed using gauze. The average strength (g /
25 mm width), and the average value of the number of test pieces n = 5 is taken as the adhesive strength.

[Example code] The contents of the present invention will be explained in detail below using examples.

Here, in order to make the comparison of the descriptions simple and clear, the process order and process conditions of the manufacturing methods used in the examples are the same, so the basic process conditions are specified for each process.

That is, in the experiments described below, unless otherwise specified, all of the samples were formed into in-mold molded products through the following step 100 or 200.

■ Process of converting resin particles into crosslinked resin particles Shredded low-density polyethylene [Santic LD, trade name; manufactured by Asahi Kasei Industries, melting point 117°C] is impregnated with dicumyl peroxide in a water suspension system and heated to 45°C at 160°C. Gel fraction after heating for 5 minutes
0% (extracted with boiling xylene for 8 hours), average particle size 1.2m
m crosslinked polyethylene resin particles.

0 Step of turning crosslinked resin particles into foamed particles Put the crosslinked resin particles and dichlorodifluoromethane liquid into an autoclave, raise the temperature while stirring, and impregnate with the above volatile foaming agent at 80°C for 1 hour, then place in a foaming device. Pressure 0.55Kg
/cm2G of water vapor for 40 seconds to achieve a foaming ratio of 6.
cc/g cross-linked polyethylene foam particles.

0 Process of increasing the expansion ratio of foamed particles The foamed particles are placed in an autoclave and held in a nitrogen gas atmosphere at a temperature of 80°C and a pressure of 15 kg/cm2・G for 8 hours to impart re-expansion ability. It is stored in a device and heated and foamed with water vapor at a pressure of 0.65 kg/am2·G for 20 seconds to form foamed particles with an expansion rate of 27 cc/g.

■ The process of turning expanded particles into molded bodies in a mold The foamed particles with an expansion ratio of 27 c c / g (approximately the same as the expansion ratio of an in-mold molded body) are stored in a sealed container, and the original bulk volume is reduced to 63 cm in air at room temperature. % (compressibility ratio 37%), and while maintaining that state, it was filled into an in-mold mold (inner dimensions 300 mm x 300 m x 25 mm) with steam holes, and the pressure was 1.4 K g / cm 2 · G. (The melting point of expanded particles + 9℃) is heated with water vapor to expand and expand the particles.
After fusing, it is cooled to form an in-mold molded product (the target expansion ratio of the molded product in this case is 25 cc/g).
.

[Example/Comparative Example-11 This experimental group investigated how to obtain the target modification effect by fixing a fine powder modifier on the surface of the foamed particles obtained through the process (1) above. This shows how difficult the technology is. Here, for the sake of convenience, the difficulty will be expressed based on the manufacturing method of the present invention and compared with a case where the requirements are not met. Furthermore, as well-known techniques close to the present invention, the technical levels of the four publications cited in the prior art section of the text are also provided as reference examples.

Therefore, below, focusing on the differences in the method conditions for fixing the modifier to the expanded particles, the differences by experiment number will be clearly explained.

The basic conditions for this experiment are shown below.

i) Foamed particles; expansion ratio 6cc/g 1300g amount i
f) Adhesive resin; low density polyethylene (Santic LD
PA0025; manufactured by Asahi Kasei Industries, average particle size 40 mesh pass, melting point 104°C) 5% by weight 1ff) Modifying material:
Conductive carbon black [Carbon EC-P600JD
, product name; manufactured by Lion Corporation] 0.5% by weight iv) Mixer used 1) High shear mixer [Henschel mixer FM-20
B, Product name: Manufactured by Mitsui Miike Kakoki Co., Ltd.] Volume: 20 Rotary blade speed: Inverter type continuously variable temperature detection position: Deflector tip (J type 1.5mmφ detection end) Temperature indicator: Digital temperature indicator (RKCDP) -20A, trade name; manufactured by Rikagaku Kogyo Co., Ltd.) iv-2) Low shear mixer [Ribbon Blender RB20,
Product name: Manufactured by Satake Kagaku Kikai Kogyo Co., Ltd.] Volume: 201 Rotary blade speed: 50 revolutions/min Temperature detection position: 20 mm inside the tank from the machine wall (J type 1.5 m
mφ detection end) Temperature indicator; Same specifications as 1v-1 (blank below) Experiment No. 1 (Example) The foamed particles of i were supplied to a 1v-1 mixer whose machine wall jacket was controlled at 106°C, The mixer was rotated at 1400 times/min (equivalent to a circumferential speed of 19.4 m/see) for high shear mixing, and the surface temperature of the foamed particles (according to the detection end attached to the deflator) was raised to 106°C, and the temperature of the jacket part was increased. 70℃
The surface temperature of the foamed particles was maintained by controlling the cooling temperature to a range of 75°C. In this state, a 30% amount of the adhesive resin was continuously injected onto the particles in the mixing tank over a period of 1 minute, and mixed for 4 minutes to entangle the surfaces of the particles with the adhesive resin.

After that, the entire amount of the modifier is supplied using the same injection and supply procedure as above and mixed for 1 minute, and the modifier is sprinkled on the adhesive resin on the particle surface and entangled, and the remaining 70% of the amount is adhesive. The resin was fed using the same pouring procedure as above and mixed for an additional 5 minutes. In order to maintain the surface temperature of the expanded particles at 106°C±1°C during mixing after injection of the modifier, it was necessary to raise the jacket temperature to 80°C and then gradually lower it to 70°C.

After the above mixing, rotate the mixer at 500 times/min (peripheral speed 6.9
m/sec equivalent), the jacket temperature was adjusted to 20°C, and the foamed particles were cooled for 6 minutes until the surface temperature reached 95°C, and then taken out. The entire surface of the obtained expanded particles was covered with small pieces of the adhesive resin containing the modifier, and was firmly fixed to the negative side. The foamed particles after the treatment were made into an in-mold molded article by the above-mentioned step O2.

Experiment No. 2 (Example) The injection and supply of the contact resin and the modifier and the mixing time after the injection and supply were determined by mixing for 4 minutes after supplying the entire amount of the adhesive resin and mixing for 4 minutes after supplying the entire amount of the modifier. The same experiment as above Experiment No. 1 was repeated except that the procedure was changed to two stages.

At first glance, the appearance of the obtained expanded particles was similar to that of Experiment No. 1, but upon closer inspection, the modifier contained in the adhesive resin appeared to be tangled somewhat roughly.

Experiment No. 3 (Comparative Example) The timing of mixing the foamed particles and the adhesive resin was changed to mixing the adhesive resin with the foamed particles that had not been heated and mixed, that is, the foamed particles were mixed at room temperature. and the entire amount of the adhesive resin is supplied to a 1v-1 mixer with a jacket temperature of 70°C, and the surface temperature of the expanded particles is brought to 106°C by shear heat generation during mixing; The same experiment as Experiment No. 12 was repeated, except that the mixing times before and after were extended to 15 minutes to improve mixing.

In the obtained expanded particles, fixation of the adhesive resin partially entangled with the modifier was observed on the particle surface, but the fixation was weak. Also, some of the foamed particles taken out had a diameter of 0.5~
Clumps of a mixture of the modifier and the adhesive resin of about 3 mm were found here and there.

Experiment No. 4 (Comparative Example) An experiment in which no adhesive resin was used, that is, a modifying material was directly supplied to the expanded particles that had been mixed and heated to 106°C.
The same experiment as Experiment No. 12 was repeated except that the mixture was mixed for 5 minutes.

Although the resulting particles had a thin layer of modifier attached to their surfaces, a large amount of the modifier in the form of fine powder was also extracted.

Experiment No. 5 (comparative example) The adhesive resin was a pellet-shaped (1 mmφ x 1 mm length) ethylene-vinyl acetate copolymer [melting point 95°C, vinyl acetate content 12%, M112 g/10 minutes, and the mixing times before and after were adjusted respectively. The same experiment as Experiment No. 2 was repeated except that the time was extended to 15 minutes to improve mixing.

The obtained particles had the modifying material partially attached to their surfaces, and the amount of attached particles was small as a whole.

In addition, among the foamed particles taken out, lumps of adhesive resin whose surface was covered with a modifier were found here and there, and a large amount of fine powder of the modifier was also present.

Experiment No. 6 (Comparative Example) The injection and supply of the adhesive resin was changed to a molten adhesive resin, that is, the adhesive resin was brought to a molten state at 106°C in a hot melt applicator in advance, and a diameter of 2.
The experiment No. 12 was repeated except that the fluid was supplied from a mm discharge port.

The obtained particles were a mixture of those in Experiment No. 3 and those in Experiment No. 094, and a considerable amount of the modifier was attached to the rotor blade of the mixer via the adhesive resin. A phenomenon was observed.

Experiment No. 7 (comparative example) The entire amount of the modifier was mixed in advance in the adhesive resin supplied in a fluidized manner, the mixing stage was set to one stage, and the mixing time was extended to 20 minutes to improve mixing. The same experiment as Experiment No. 2 was repeated, except for changing the direction of movement.

In the obtained particles, almost no adhesion of the modifier was observed on the surface, and small pieces of the adhesive resin containing the modifier were scattered within the expanded particles.

Experiment No. 8 (Comparative Example) The form of the adhesive resin was changed to one that is viscous at room temperature, that is, the adhesive resin was changed to an ethylene-vinyl acetate copolymer [
Melting point 92°C, vinyl acetate content 14%, MI t 5g/
The same experiment as Experiment No. 12 was repeated except that the solution was changed to one dissolved in 400 cc of toluene.

The particles obtained were similar to experiment NO33. However, many of the clumps of the modifier and adhesive resin that were found here and there were such that the modifier was fixed to the surface of the adhesive resin, and the clumps were also large, with a diameter of 3 to 10 mm.

Experiment No. 9 (comparative example) The adhesive resin was in the form of a paint (a state in which the adhesive resin of Experiment No. 8 was mixed with a modifier), and the mixture was changed to 1.
In other words, the amount of toluene in the adhesive resin in Experiment No. 018 was changed to 600 cc, the modifier was changed to a liquid substance dispersed in the solution, and the mixing stage was changed to one stage. The same experiment as experiment N092 was repeated.

The obtained particles had a thin layer of adhesive resin containing the modifier fixed to the entire surface of the particles.

However, a coating film of the modifier and adhesive resin had been formed on the walls and rotor blades of the mixer, so much so that it appeared black.

Experiment No. 10 (comparative example) Instead of using an adhesive resin, the surface of the foamed particles was swollen and the modifier was fixed there. In other words, toluene was used instead of injecting and supplying the adhesive resin. The same experiment as Experiment No. 082 was repeated, except that the spray was changed to 200 cc and the mixing time was shortened to 2 minutes.

The amount of modifier attached to the surface of the obtained particles appeared to be improved compared to that of Experiment No. 34, but the expanded particles had large shrinkage and wrinkles were noticeable, and the fine powder state There were still many modified materials.

Experiment No. 11 (Comparative Example) A device to improve the mixing of the adhesive resin and the modifier, namely, changing to one in which the fine powders of both were sufficiently mixed in advance, and Set to 1 step and mix time 15
Experiment No. 2 was repeated except that the time period was extended to 1 minute.

The obtained particles had less adhesion of the modifier on the surface than in Experiment No. 094, and no fixation of the adhesive resin was observed, and most of the supplied modifier and adhesive resin mixture were taken out as they were. I've been

Experiment No. 12 (comparative example) This is the same improvement as Experiment No. 11, but the difference from Experiment No. 11 is that the mixture of adhesive resin and modifier is
Same as Experiment No. 11, except that the modification material was mixed and dispersed in the molten adhesive resin, and the mixed solid was crushed to obtain a fine powder product (particle size: 40 mesh). The experiment was repeated.

No modification material was observed on the surface of the obtained particles, and most of the supplied fine powder mixture had a diameter of 0.5~
It was taken out in 1mm chunks.

Experiment No. 13 (Comparative Example) When high shear force mixing was not used, that is, the mixer was rotated at 200 times/min (corresponding to a circumferential speed of 2.8 m/sec), and the surface temperature of the foamed particles was 101 m/sec from the jacket. The adhesive resin was changed to maintain heating at ~105°C, and the adhesive resin was a fine powder of ethylene-vinyl acetate copolymer [melting point 95°C, vinyl acetate content 12%.

The experiment of Experiment No. 092 was repeated except that the MI was changed to 12 g/l, 0/1 particle size, and 40 mesh Pasco.

The obtained particles had small pieces of adhesive resin containing the modifier sparsely attached to their surfaces, but approximately half of the supplied modifier and adhesive resin had adhered to the machine wall surface. .

Experiment No. 14 (comparative example) When using a mixer with a different specification when high shear force mixing is not used, that is, the mixer is set to IV-2, and the number of rotations of the rotor is 50 times/min. Experiment No. 002 was repeated, except that the surface temperature of the foamed particles was maintained by heating from the jacket to 104 to 106° C. to try to fix the modifier.

The obtained particles were somewhat worse than those in Experiment No. 13, and the amount of modifier/adhesive resin that adhered to the machine wall surface and rotating body was about two-thirds of the amount supplied. there was.

Experiment No. 15 (Reference example) The entire process of fixing the modifier to expanded particles is described in Japanese Patent Application Laid-Open No. 59-1
This is a modification to that described in Example 1 of Publication No. 69199. That is, the entire process of fixing the modifier was performed by applying a modification treatment solution [63% by weight of modifier fine powder (Donna Carbo 5244, trade name; manufactured by Inu Nippon Ink Co., Ltd.) to the surface of 400 g of foamed particles;
Surfactant (sodium dodecylbenzenesulfonate i)
2% by weight and 36% by weight of water)] was deposited using one tumbler method. After drying this, an in-mold molded body was prepared using the process conditions described in section 0 above in the main text.

The difference lies in the fact that the target resin is different from polystyrene (published method) compared to vevolystyrene (invention).

Experiment No. 16 (Reference Example) The surface fixing process of the modifier was changed to that described in JP-A-63-125537, that is, the particles to be treated were added to 700 g of the crosslinked resin obtained in the above process. , the modifier is a surfactant, an antistatic agent [quaternary ammonium salt (cation A
B): 7 g of Nippon Oil & Fats Co., Ltd.] at 1 high shear mixing rotation speed.
730 times/min (peripheral speed 24 m/sec),
The surface temperature of each resin particle was changed to 110° C., and the modifying material (antistatic agent) was set to be fixed on the surface of the resin particles mixed in a softened state. I tried again. However, in this experiment, the target particles were changed to polyethylene, so it was impossible to foam 50 times in one step, and the impregnation conditions for the blowing agent, foaming conditions, molding conditions, etc. were also the same as those for polystyrene described in this publication. Since the conditions were different from the actual ones, we decided to adopt the conditions described in the above-mentioned process 000 of the present application in an effort to obtain an in-mold molded body.

Experiment No. 17 (Comparative Example) A follow-up test was carried out on the surface fixing process of the modifier described in Example 2 of JP-A-63-275648. That is, in an autoclave with an internal capacity of 1.5°C, 250g of crosslinked resin particles obtained in the above process and a modifier [antistatic agent:
Suspend 25g of polyoxyethylene alkyl fatty amine (trade name "Denone 311L" manufactured by Marukata Yuka Kogyo Co., Ltd.), raise the temperature to 90°C in 1 hour, and after raising the temperature, heat the autoclave with nitrogen to 5Kg/cm"G. The autoclave was pressurized and maintained in this state for 2 hours.Then, the autoclave was cooled down to room temperature over 30 minutes and the pressure was returned to atmospheric pressure.After this treatment, the particles underwent the OOO process described above in the main text, and were expanded to a foaming ratio of 25 times. The reason for this change is that the density of the target resin is different.

Experiment No. 17' (Reference example) An attempt was made to reproduce the surface fixing process of the modifying material as described in JP-A-60-195134 (Example 2), that is, the particles to be treated were Foaming ratio: 27 cc
/g of polyethylene foam particles, vinyl acetate emulsion (manufactured by Daicel Chemical Industries, Ltd., trade name [Sevian A22126J)] was used as the adhesive resin, and natural flake graphite powder (manufactured by Nippon Graphite Industries, trade name) was used as the conductive fine powder. rC3PEJ
and carbon black (manufactured by Lion Co., Ltd., trade name: Ketchen Black ECJ) and carbon fiber (manufactured by Toho Rayon Co., Ltd., trade name: rCF Milled Fiber) at a ratio of 3:1, respectively.
The mixture was premixed at a ratio of 1:1, and a low shear mixing 1iV-2 was used as a mixer in an effort to reproduce the conditions of Example 2 of the same publication as faithfully as possible. However, in this experiment, the target particles were polyethylene and the expansion ratio was 2.
7 c c / g (for comparison with the examples of this application), so the differences in conditions can be explained with reference to the description of the examples in another publication, ie, Japanese Patent Application Laid-Open No. 58-92540. While searching for the optimal conditions, we obtained foamed particles treated with a modifying material. The in-mold molding conditions were as described in the Examples of the present application to obtain a molded product with an expansion ratio of 25 cc/g. The obtained molded product was darker than the product of the present invention, and it appeared that the particles were completely fused.

However, the inside of the mixer used for the work and the inner wall of the mold were black and contaminated, and when the particles and molded products were touched, the modifier was transferred to hands, etc., and the modifier was not fixed. It was impressive that the properties were noticeably poor and that it took 12 hours to dry after treatment.

The resulting molded bodies of Experiments No. 011 to 17' were evaluated for fusion properties, appearance quality, level of conductivity, maintenance of conductivity, and fixation state of the modified material using the methods described in the text, and the results were evaluated in the following section. It is summarized in table 1. At this time, the observation results of the fixing process with modification and special notes regarding the molded body are summarized in the remarks column.

As shown in the results in Table 1, when the object to which the modified fine powder is to be fixed is foamed particles, it is necessary to use a mixing means that utilizes heat generation under high shear force for heating and mixing. (Relationship between experiment No. 1.2 and experiment No. 13.14)
In order to effectively utilize the heat generated by this high shear force, first, a finely powdered adhesive resin is sprinkled on the target expanded particles, which have already been heated under the high shear force, and then modified. The necessity of adopting the order of supplying textured fine powder is made clear in relation to various comparative examples. That is, for example, experiment No. 33 is when the foamed particles are not heated, experiment No. 004 is when the adhesive resin is absent, and experiment No.
05-9 is Experiment N when the adhesive resin is not in fine powder form.
o, 10 is when the foamed particle surface is swollen, experiment No.
11 and 12 show the relationship when the mixing order is changed, and in both cases, the surface fixation of the modified fine powder becomes insufficient, and the expected modification effect (level of conductivity) cannot be obtained. However, it has been shown that the sustainability of the modification effect (sustainability of conductivity) is undesirable.

Furthermore, in Table 1, JP-A No. 59-169119 (Experiment No. 15) and Jikai No. 63-125537 (
Experiment No. 16), Japanese Unexamined Patent Publication No. 63-275648 (
Experiment No. 17), Japanese Patent Application Laid-open No. 195134/1983 (
The content of Experiment No. 17') is presented as a reference example. This result indicates the current state of the art. That is, in Experiment No. 15, the modification material was not fixed and no modification effect was observed.

In experiment No. 16.17, even though the modification effect was obtained, the maintenance of the effect could not be expected at all. The difference with the molded product of the present invention is whether the modifier fixed on the surface of the molded product is carbon black (the present invention) or a surfactant (reference example). It is. Experiment No. 17'
In the initial modification effect, the product of the present invention stands out. However, the sustainability of its effects is extremely poor and it easily falls off.
The quality of the molded product is poor. The difference between this Experiment No. 17' and the product of the present invention is that in Experiment No. 1, the fixing means for the modifier was an emulsion resin film.

17' and the product of the present invention with a heat-sealable film, the extent of the difference can be clearly distinguished using the difference in the value of "fixed state of modified product" as a structural indicator.

As mentioned above, according to the results shown in Table 1, the present invention is superior to the current state of the art in terms of the extremely high level of modification effect obtained and the sustainability of the effect, and is an excellent invention. I can say that there is. Furthermore, the results of the comparative examples show that this effect was achieved by a method and conditions that could not be imagined based on the current state of technology (although the results of the comparative examples show that it was achieved based on original ideas).

[Example/Comparative Example-2] This experimental group illustrates the relationship between the amount of modifier that can be employed in the method of the present invention and the modification effect obtained. This experiment will ultimately show the relationship between the amount of modifying material contained in the molded body and the modification effect of the molded body referred to in the present invention. Therefore, we have decided to provide a comparative product using the kneading method.

(Experiment Nos. 18 to 21: All Examples) The amount of carbon used in Experiment No. 011 of Example/Comparative Example 1 was 0.3, 1
．． The same experiment as Experiment No. 1 was repeated except that the amounts were changed to 0, 2.0, and 3.0% by weight, respectively, to obtain in-mold molded bodies.

(Experiment No. 22 to 25; all examples) Same experiment N
o, 1, the carbon species was ``Conductive Carbon Black #3250 (product name; manufactured by Mitsubishi Chemical Corporation), and the amount used was 0.5゜1.0, 2.0, 3.0% by weight. Except for each change, the same experiment as Experiment No. 61 was repeated to obtain an in-mold molded body.

(Experiment No. 26-29: All comparative examples) Same experiment N
For 011, how to use carbon: ■ O, 1, 0, 2, 0, 3, each of carbon in the resin before entering the process.
An in-mold molded article was obtained by repeating the same experiment as in Experiment No. 1, except for changing the method to thoroughly kneading 0% by weight directly.

The obtained molded bodies of Experiment No. 18 to 29 were Experiment No.
1 and the surface resistance value (Ω) of each using the method described in the text.
were evaluated, and the results are summarized in Figure 3, organized by system.

In other words, in Figure 3, the vertical axis shows conductive water? 1! (Surface resistance value Ω of the compact), and the horizontal axis is the amount of modifying material contained in the compact (
weight percent of carbon). The numbers in the figure represent each experiment N.
o. Therefore, graphs I and II show examples of the present invention with different types of carbon, and graph (2) shows a comparative product with a different amount of kneading.

According to the results shown in FIG. 3, according to the present invention, the amount of modifying material is 3
A sufficient weight % can be adopted, and the resulting modification effect [conductivity level] can be maintained at a level of 10'Ω. This modification effect varies depending on the type of carbon used and the amount of carbon used, but the modification effect that reduces the conductivity level to 1 x 104Ω or less can be easily achieved, and 10"Ω
It can be seen that the effect is different from that of the kneaded product (graph III) in which no modification effect occurs.

The effect shown in FIG. 3 is the effect that the foamed particles with the modifier fixed to their surfaces are tightly fused and integrated, and is an epoch-making effect disclosed for the first time by the present invention. I can say that.

[Example 31] This experiment demonstrated the greatest feature of the "foamed particles with a modifier fixed to their surface" used in the production of the present invention, that is, the modification effect remained even when the expansion ratio of the foamed particles was gradually increased. This demonstrates the advantage that the drop phenomenon is small. In other words, this shows the advantage of the manufacturing method of the present invention that if the above-mentioned characteristics of the expanded particles are used to obtain an in-mold molded product, molded products with a wide range of expansion ratios can be freely obtained according to the purpose of use. This also proves the characteristic of the molded product that the obtained molded product retains the modification effect.

That is, for experiment No. 1.2 of Example/Comparative Example-1,
By changing the conditions for additionally injecting pressurized nitrogen to "increase the expansion ratio" in the 0th process, each expansion ratio was increased to 5.1015.21.
．． Experiment No. 1.2 was repeated, except that 32 cc/g foamed particles were created and molded objects were formed. At this time, the molded bodies obtained by repeating Experiment No. 011 were designated as Experiment No. 30 to 34 in order, and Experiment No.
Experiment No. 35~
It was numbered 39. The surface resistance of each of the obtained molded bodies was evaluated by the method described in the text, and the results were evaluated as Experiment No. 1.
Figure 4 is a summary of the results in Figure 2. Therefore,
The graph ■ in Figure 4 shows the foamed particles of the experiment N011 system.
Graph V shows the relationship between the foaming ratio of molded bodies obtained by successively increasing the foaming ratio of the expanded particles of the experiment N092 series and the modification effect [level of conductivity] exhibited by the molded bodies. .

According to the results shown in FIG. 4, experiment No. used in the present invention,
Even if the foamed particles of No. 1.2 are used as a molded product by increasing the expansion ratio, the modification effect of the resulting molded product will not decrease much, and the conductivity level of Ix104 to lx10'3Ω is sufficient. This indicates that the molded product is held at a constant temperature. In particular, it can be seen that in the case of the expanded particles of the experiment No. 11 series, even when the expansion ratio is increased, the modification effect decreases very little, and it can be used to form molded articles with a wider range of expansion ratios.

Figures 1 and 2 are enlarged views of the surface condition of the molded product of Experiment No. 1.2. The difference between the two is that the small pieces of adhesive resin containing the modifier (the part that looks black) are dispersed and developed, and in Figure 2 (Experiment No. 2), the scattered pieces are three-dimensional. Figure 1 (Experiment N
o, 1) can be seen as a difference in that it develops with a mesh-like part. In other words, in Experiment No. 1, even if the expansion ratio is increased, if the foamed particles are fused together to form a molded body, the probability that this mesh part is connected somewhere is as follows. It is presumed that this results in maintaining high conductivity.

The effect shown in FIG. 4 above is a unique phenomenon effect exhibited by the present invention, and represents the greatest feature of the present invention.

[Example 4] This experiment shows another major feature of the "foamed particles with a modifier fixed to the surface" used in the present invention, that is, the robustness of the fixed state of the modifier. In other words, the foamed particles to be subjected to in-mold molding are transported by pressurized gas when they are transported and filled into the mold, so the robustness during transport depends on the manifestation of the modification effect of the resulting molded product. This is the key. This experiment was planned from this perspective. That is, before the expanded particles of Experiment No. 1.2 (expansion ratio 27 times) were subjected to molding, they were repeatedly conveyed 5, 10, and 20 times through a circulating air transportation system with a total length of 30 m as shown in Fig. 5. The experiment No. 1.2 was repeated except that this was used for molding.The conveyance conditions in this case were as shown in FIG. 5, where the inner diameter of the pipe was 100 mm.

Length 30m (horizontal part 10m x 2, rising part 4m, 6m
), a wind speed of 10 m/s, and a mixing ratio of air and particles of 3:1.

Table 2 summarizes the level of modification effect (level of conductivity) of the obtained molded bodies by the number of repeated conveyances.

According to the results in Table 2, both the foamed particles used in Experiment No. 1.2 showed very little reduction in the modification effect due to repeated conveyance, and it was demonstrated that they had a strong surface adhesion state. . The effects shown in Table 2 are considered to be the basis for the molded article obtained by the method of the present invention to have and maintain an excellent modification effect.

[Example-5] This experiment demonstrated that the molded product obtained by the method of the present invention has the structural strength, appearance quality, and molded product characteristics required for the molded product, that is, it has practical characteristics. This proves that the reforming effect was achieved in a state where the

In other words, cases where the modification effect is conductive are classified as A group, and representative examples thereof are Experiment No., 31.33゜34, and Experiment N.
o, 36.38.39 were selected and used. On the other hand, the case where the modification effect is flame retardant is classified as Group B, and the above experiment N is applied to this case.

Corresponding to that of 31.33.34, the modifying material was decabromodiphenyl ether [trade name: Pyroguard 5R].
200AW (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Coro, a mixture of 9% by weight and antimony trioxide (manufactured by Nippon Mining Co., Ltd.) 0.3% by weight, except that the amount of adhesive resin was changed to 8% by weight. Experiment No. above.

The same experiments as those in 31, 33, and 34 were repeated, and the obtained molded bodies were assigned experiment numbers 40, 41, and 42, respectively, and used for experiments.

A total of nine types of molded bodies were evaluated for fusion properties, appearance quality, and repeated compression set using the methods described in the text, and the respective modification effects (conductivity or flame retardancy) were evaluated. The results are summarized in Table 3 along with the evaluation.

According to the results in Table 3, the molded product obtained in the present invention has all the practical properties as a molded product, and also has a high level of modification effect (conductivity or flame retardancy). It has been demonstrated that the molded product is highly useful.

[Example 6; Experiment No. 50 This example shows one of the most desirable embodiments of the manufacturing method of the present invention. The main point lies in the method of supplying the adhesive resin and the modifier when fixing the modifier to the foamed particles.

In order to clarify the contrast, an experiment similar to Experiment No. 1 was conducted. The differences in the conditions in this case from Experiment No. 011 are as follows: i) After 30% of the adhesive resin is supplied and mixed with the heated foamed particles, the modifier (carbon black) and the remaining 70% are mixed. changing the method of supplying the adhesive resin with the adhesive resin to a method in which both are premixed in advance, and if) the mixing time after supplying the above mixture is changed from 5 minutes to 3 minutes. The experiment was the same as Experiment No. 011 except for the following two points: shortened to . The obtained molded body was evaluated for fusion properties, appearance quality, compression set, cyclic set, conductivity level, conductivity maintenance, and fixation state of the modified product using the methods described in the text. , I compared the results with 1.

The other evaluation results showed that Experiment No. 50 was somewhat superior to Experiment No. 11, and there was no major difference, but it was found that the level of conductivity was extremely high, about 100 times. This effect is noteworthy in that it can be obtained in conjunction with the effect of shortening the mixing time.

[Effects of the Invention] As has been explained in detail and clarified above, the manufacturing method of the present invention has the above-mentioned configuration, so that the foamed particles having the modifier firmly fixed to the surface thereof can be formed in a mold. It has the advantage of being able to expand and fuse. The advantage of this is that when evaluated as a molded product, it is possible to maintain a high level of modification effect (conductivity, H flammability), and the practical properties of the molded product are not impaired. It embodies the surprising effect. Accordingly, the present invention
This is the first time to provide the industry with a practical molded product with excellent modification effects, which has been long-awaited but impossible to achieve. In addition, the manufacturing method of the present invention does not contaminate the mixer, mold, etc. compared to the emulsion resin deposition method, does not require a long drying time, and completes fixing of the modifier in a very short time. There are advantages to being able to do so. Therefore, the present invention is an excellent invention that plays an extremely important role in industry.

[Brief explanation of drawings]

Figures 1 and 2 show the state of adhesion of small adhesive resin pieces (black parts) containing the modifier to the surface of the molded product in the mold (Figure 1 shows the mesh-like part, Figure 2 shows the scattered parts). Micrograph showing ( )
(approx. 150x), Figure 3. Figure 4 is a diagram of the experimental results, and Figure 5 is a diagram of the experimental equipment.

Claims (1)

[Scope of Claims] 1) Foamed particles with a modifier, which is a fine inorganic or organic powder, fixed on the surface of the particles are filled into a mold and heated to expand and fuse the foamed particles to each other, thereby forming the particles. [1] The method for fixing the modifier on the surface of the foamed particles is performed by heating and temperature-controlled polyolefin resin foam particles under high shear mixing. A polyolefin adhesive resin fine powder is supplied to the foamed particles, and the adhesive resin is dispersed and fused onto the surface of the foamed particles by heating and mixing, and then a modifier fine powder is supplied thereon and heated and mixed to form the foamed particles. It is a method of dispersing and fixing the adhesive resin containing the modifier on the surface; [2] The heating performed in the mold is at a temperature in the range of 2°C above the melting point of the expanded particles to 14°C above the melting point. 1. A method for producing an in-mold molded article using polyolefin resin foam particles, characterized in that steam heating is performed. 2) In an in-mold molded body made of polyolefin resin foam particles in which a modifier, which is a fine inorganic or organic powder, is fixed on the surface of the particles, the modifier is a fine powder of carbon black, and the modifier is a fine powder of carbon black. The content is 3 to 0.1% by weight based on the amount of resin, and the fixation of the polyolefin adhesive resin containing carbon black in the molded product is 1 in a peel test using adhesive tape.
It is in a strong fixing state with a low value of 0% or less, and the surface resistance value of the molded product is 1 x 10^4 Ω to 1 x 10^1
A polyolefin resin in-mold molded article characterized by a resistance in the range of ＾3Ω. 3) In an in-mold molded article made of polyolefin resin foam particles in which a modifier, which is an inorganic or organic fine powder, is fixed on the surface of the particles, the modifier is a fine powder flame retardant, and the content thereof is The amount is 5 to 0.1% by weight based on the amount of resin, and the fixation of the polyolefin adhesive resin containing flame retardant in the molded product shows a low value of 10% or less in a peel test using adhesive tape. It is in a strong fixed state, the fusion property between the foamed particles constituting the molded object shows a value of 80% or more, and the compression set when compressed at 25% measured as a molded object is less than 6%. 1. A polyolefin resin in-mold molded article comprising: 4) In an in-mold molded article made of polyolefin resin foam particles in which a modifier, which is an inorganic or organic fine powder, is fixed on the surface of the particles, the modifier is a coloring pigment, and the modifier is a coloring pigment. The amount is 5 to 0.1% by weight based on the amount of resin, and the fixation of the pigment-containing polyolefin adhesive resin in the molded article shows a low value of 10% or less in a peel test using an adhesive tape. It is in a strong fixed state, the fusion property between the foamed particles constituting the molded body shows a value of 80% or more, and the compression set when compressed at 25% measured as a molded body has a value of less than 6%. 1. A polyolefin resin in-mold molded article.