JP4332587B2 - INORGANIC FOAMING PROMOTING AUXILY, PROCESS FOR PRODUCING THE SAME - Google Patents

Description

  The present invention relates to an inorganic foaming accelerating aid that accelerates decomposition of a pyrolytic foaming agent, a method for producing the same, and a polymer composition using the same.

  In foam molding of plastics and rubbers, a method of molding a foam by blending a pyrolytic foaming agent and foaming it is known. It is known that by allowing zinc oxide to coexist in such a pyrolytic foaming agent, the decomposition temperature of the pyrolytic foaming agent can be lowered and the decomposition of the foaming agent can be promoted.

  Various zinc compounds have been studied as foaming promotion aids for the above pyrolytic foaming agents (for example, Patent Documents 1 and 2).

  As a metal oxide, active zinc white is known as a foaming promotion aid. However, active zinc white is composed of extremely fine zinc oxide particles, and thus agglomerates to form relatively large secondary particles, which tend to be insufficiently dispersed in resin and rubber, and have an ineffective foaming effect. It tends to be uniform.

Moreover, the composite particle | grains which coat | covered the surface of calcium carbonate with the zinc oxide are known (patent document 3). However, such composite particles are not necessarily superior foam promoting aids compared to activated zinc white.
JP 53-145876 A JP 58-201825 A JP 60-264324 A

  An object of the present invention is to promote the decomposition of a foaming agent with a small amount of zinc, and to provide an inorganic foaming promotion assistant capable of foaming the foamed cell with a uniform and high foaming ratio. It is in providing a manufacturing method and a polymer composition using the same.

  The inorganic foaming accelerating aid of the present invention is an inorganic foaming accelerating aid that promotes the decomposition of the thermal decomposition type foaming agent, and carries zinc oxide fine particles or basic zinc carbonate fine particles on the surface of silicate particles. It is characterized by that.

  According to the present invention, the decomposition of the foaming agent can be promoted with a small amount of zinc, and the size of the foamed cells can be foamed uniformly and at a high foaming ratio.

  In the present invention, zinc oxide fine particles or basic zinc carbonate fine particles are supported on the surface of the silicate particles. The surface of the silicate particles has an affinity for the zinc oxide fine particles and the basic zinc carbonate fine particles, and therefore, the zinc oxide fine particles or the basic zinc carbonate fine particles can be uniformly supported. Therefore, in the inorganic foaming accelerating aid of the present invention, fine zinc oxide fine particles or fine basic zinc carbonate fine particles are supported on the surface, and the decomposition of the pyrolytic foaming agent is caused by the surface activity of these fine particles. Can be effectively promoted.

  Alternatively, the inorganic foam promoting aid of the present invention is excellent in dispersibility in polymers such as plastic and rubber. For this reason, the effect of promoting foaming can be exhibited uniformly in the polymer, and the decomposition of the foaming agent can be promoted uniformly with a small amount of zinc. For this reason, the polymer material can be foamed with a uniform and fine foam cell size.

  In the present invention, the supported amount of zinc oxide fine particles or basic zinc carbonate fine particles is preferably in the range of 6 to 75% by weight in terms of metallic zinc. Here, the supported amount in terms of metal zinc is calculated from the following formula using the Zn converted weight obtained by converting the supported zinc oxide fine particles or basic zinc carbonate fine particles into metal zinc. be able to.

  Metal zinc equivalent loading (% by weight) = (Zn equivalent weight) / (weight of inorganic foam accelerating aid) If the loading is less than the above range, the size of the foam cell is finely and uniformly high. In some cases, foaming cannot be performed at the expansion ratio. Moreover, even if there is too much carrying amount than said range, the effect accompanying it may not be acquired but it may become economically disadvantageous.

BET specific surface area of the silicate particles carrying the zinc oxide fine particles is preferably in the range of 10~55m ² / g, in the range of more preferably 15 to 50 m ² / g, more preferably 20~45m ² / The range of g.

It is preferable that the BET specific surface area of the silicate particle | grains which carry | supported the basic zinc carbonate fine particle is the range of 25-90 m < ² > / g, More preferably, it is 30-85 m < ² > / g, More preferably, it is 35-80 m < ² >. / G.

  Basic zinc carbonate fine particles are finer than zinc oxide fine particles, and can be fine particles having a high BET specific surface area. Therefore, as described above, when the basic zinc carbonate fine particles are supported, the BET specific surface area is higher than when the zinc oxide fine particles are supported.

  If the BET specific surface area becomes too low, contact with the foaming agent is not sufficiently formed in the polymer material, foaming becomes uneven, and the foaming ratio may be lowered.

  Moreover, when the BET specific surface area becomes too high, unsupported free zinc oxide or basic zinc carbonate is mixed, which becomes aggregated particles, and a uniform foam may not be formed. Moreover, since the carrying amount of zinc oxide or basic zinc carbonate is relatively increased, it may be difficult to obtain an economic merit.

  As the silicate particles in the present invention, aluminum silicate mineral particles are preferably used. Examples of the silicate particles other than the aluminum silicate mineral particles include talc, mica, feldspar, bentonite, basic magnesium carbonate, silica, calcium silicate and the like.

  Examples of the aluminum silicate salt mineral particles in the present invention include at least one selected from kaolinite, halloysite, pyrophyllite, and sericite. In the present invention, the aluminum silicate mineral particles are preferably anhydrous aluminum silicate mineral particles. Examples of anhydrous aluminum silicate salt particles include those obtained by firing at least one selected from kaolinite, halloysite, pyrophyllite, and sericite. For example, those obtained by firing these clay minerals composed of fine particles having a particle size of 2 μm or less having a content of 80% or more at a temperature of 500 to 900 ° C. can be mentioned.

In the inorganic foaming promoting aid of the present invention, the ratio of Zn in the zinc oxide fine particles or basic zinc carbonate fine particles to the Al ₂ O ₃ in the aluminum silicate salt mineral particles (Zn / Al ₂ O ₃ ) is a molar ratio. The range is preferably 0.2 to 40.0, more preferably 0.4 to 20.0, and still more preferably 0.5 to 10.0. If the molar ratio is too small, the amount of zinc oxide or basic zinc carbonate to be supported on the surface decreases, and the foam cell size may be fine and uniform and a high foaming ratio may not be obtained. If the molar ratio is too large, the amount of fine zinc oxide or basic zinc carbonate particles that are not supported on the aluminum silicate mineral particles increases, resulting in poor workability in the manufacturing process and unsupported zinc oxide or base. Since uniform zinc carbonate becomes an aggregate, uniform foaming may not be obtained.

  The production method of the present invention is a method capable of producing the above-mentioned inorganic foaming promoting aid of the present invention. The step of preparing an acidic aqueous solution of zinc salt, and the presence of silicate particles The method includes a step of mixing an aqueous solution and an alkaline aqueous solution to precipitate zinc oxide fine particles or basic zinc carbonate fine particles, and supporting the zinc oxide fine particles or basic zinc carbonate fine particles on the surface of the silicate particles.

  Silicate particles carrying zinc oxide fine particles or basic zinc carbonate fine particles can be produced by the production method of the present invention. Furthermore, the silicate particles carrying the zinc oxide fine particles are treated with an ammonium salt aqueous solution, and the supported zinc oxide fine particles are converted into the basic zinc carbonate fine particles. Can be manufactured.

  In the present invention, in the presence of silicate particles, an acidic aqueous solution and an alkaline aqueous solution of zinc salt are mixed to precipitate zinc oxide fine particles or basic zinc carbonate, and zinc oxide fine particles or Basic zinc carbonate is supported.

  Specific examples of a method for depositing zinc oxide fine particles or basic zinc carbonate fine particles by mixing an acidic aqueous solution and an alkaline aqueous solution of zinc salt in the presence of silicate particles include the following methods.

  (1) Silicate particles are dispersed in an acidic aqueous solution of zinc salt, and an alkaline aqueous solution is added to the dispersion.

  (2) Silicate particles are dispersed in an alkaline aqueous solution, and an acidic aqueous solution of zinc salt is added to the dispersion.

  (3) Silicate particles are dispersed in water, and an acidic aqueous solution and an alkaline aqueous solution of zinc salt are simultaneously added to the dispersion.

  Of the above methods (1) to (3), the method (1) is particularly preferably employed.

  The acidic aqueous solution of zinc salt can be prepared, for example, by adding zinc oxide, zinc hydroxide, basic zinc carbonate, zinc sulfate, zinc nitrate or the like to the acidic aqueous solution. As zinc oxide, zinc white used as various industrial raw materials may be used. Examples of the acidic aqueous solution include aqueous solutions of hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, and the like. Moreover, you may prepare by adding water-soluble zinc compounds, such as a zinc chloride, in acidic aqueous solution.

  Examples of the alkaline aqueous solution include aqueous solutions of sodium hydroxide, potassium hydroxide, sodium carbonate, and the like. In general, when sodium hydroxide, potassium hydroxide or the like is used as an alkaline aqueous solution, zinc oxide fine particles can be deposited and supported. Further, when carbonic acid is used as the acidic aqueous solution, or when sodium carbonate or the like is used as the alkaline aqueous solution, basic zinc carbonate can be deposited and supported.

  In addition, as described above, the silicate particles supporting basic zinc carbonate are prepared by a method of treating silicate particles supporting zinc oxide fine particles with an aqueous ammonium salt solution or water suspension of silicate particles supporting zinc oxide fine particles. It can be produced by converting the supported zinc oxide fine particles into basic zinc carbonate fine particles by treating with a method such as carbonation by introducing carbon dioxide into the suspension. These treatment methods may be carried out singly or in combination.

  Examples of the aqueous ammonium salt solution include aqueous solutions of ammonium hydroxide, ammonium hydrogen carbonate, ammonium carbonate, and the like. These may be used alone or in combination of two or more.

  As described above, it can be supported as finer particles by treating with an aqueous ammonium salt solution and converting the zinc oxide fine particles into basic zinc carbonate fine particles.

  After zinc oxide fine particles or basic zinc carbonate fine particles are deposited and supported on the surface of aluminum silicate salt mineral particles, they are generally washed thoroughly, dehydrated and dried, and then pulverized.

  The polymer composition of the present invention is characterized by containing a thermally decomposable foaming agent and the inorganic foaming promoting aid of the present invention.

  Examples of the pyrolytic foaming agent in the present invention include an organic pyrolytic foaming agent and an inorganic pyrolytic foaming agent.

  As the organic pyrolytic foaming agent, any organic foaming agent that foams by thermal decomposition can be used without limitation. Typical organic pyrolytic foaming agents include ADCA (azodicarbonamide), DPT (dinitrosopentamethylenetetramine), OBSH (p, p′-oxybisbenzenesulfonylhydrazide), AIBN (azobisisobutyro). Nitrile) and the like.

  As the inorganic pyrolytic foaming agent, any inorganic foaming agent that foams by thermal decomposition can be used without limitation, and examples thereof include bicarbonate, carbonate, nitrite and the like. Moreover, a thermal decomposition type foaming agent may be used independently and may be used in mixture of 2 or more types. Further, an organic pyrolytic foaming agent and an inorganic pyrolytic foaming agent may be used in combination.

  In the polymer composition of the present invention, the content of the inorganic foaming accelerating aid is preferably in the range of 0.5 to 20 parts by weight, more preferably 0.5 to 15 parts per 100 parts by weight of the polymer. It is the range of a weight part, More preferably, it is the range of 1-10 weight part. If the content of the inorganic foaming accelerating aid is too small, it may not be possible to form a foam having a fine and uniform foam cell size and a high foaming ratio. Moreover, even if there is too much content of an inorganic type foaming promotion adjuvant, the effect accompanying it may not be acquired but it may become economically disadvantageous.

  The content ratio of the thermally decomposable foaming agent and the inorganic foaming accelerating aid is not particularly limited, but is preferably 1: 0 by weight ratio (thermally decomposable foaming agent: inorganic foaming promoting aid). A range of 0.05 to 3.0 is preferable, and a range of 1: 0.1 to 2.6 is more preferable. When the content ratio of the inorganic foaming accelerating auxiliary is too small, the foamed cell size may be fine and uniform and cannot be foamed at a high foaming ratio. Moreover, when there are too many content rates of an inorganic type foaming promotion adjuvant, the effect accompanying it may not be acquired but it may be economically disadvantageous.

  Since the polymer composition of the present invention contains the above-mentioned inorganic foaming promoting aid of the present invention, the size of the foamed cell can be finely uniform and foamed at a high foaming ratio. Production methods suitable for various raw materials, such as foamed plastics made from various plastic resins as raw materials, rubber sponges made from natural rubber and synthetic rubber as functional porous materials having characteristics such as lightness, cushioning properties and heat insulation It can be used in various foamed molded product fields depending on the cell structure and function. Typical examples of foam plastic include automotive interior materials, shock absorbers, cushioning agents, freshness-keeping materials, heat insulation packaging materials, mat materials, packaging materials, cushion materials, floaters, skin materials, pallets, and architectural forms Etc. Sponge rubber includes automotive weather strips and hose protection tubes, various cushions, foam sheets, midsole, outsole and other shoe materials, architectural sealing materials, various packings, various gaskets, OA rolls, cosmetic puffs, and heat insulating materials. Anti-vibration material, profile material, stuffing, wet suit and the like.

  Examples of the polymer include natural rubber, synthetic rubber, synthetic resin, thermoplastic elastomer, and the like. Natural rubber is a polymer material on rubber obtained from a natural plant, and has a cis-1,4-chemical structure. If it has a polyisoprene structure, a shape, a color tone, etc. will not be specifically limited. Examples of the synthetic rubber include isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber, butyl rubber, halogenated butyl rubber, ethylene propylene rubber, ethylene propylene diene rubber (EPDM), urethane rubber, silicone rubber, fluorine rubber, Examples include chlorosulfonated polyethylene, epichlorohydrin rubber, polysulfide rubber, and the like. As the synthetic resin, both a thermoplastic resin and a thermosetting resin can be used. Examples of the thermoplastic resin include polypropylene, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ultra-low density polyethylene, ethylene-vinyl acetate copolymer (EVA), and ethylene-ethyl acrylate copolymer. Copolymer (EEA), ethylene-propylene copolymer, propylene homopolymer, ethylene-propylene rubber, polybutene, butyl rubber, HIPS, PS, ABS, vinyl chloride resin, methacrylic resin, MMA-styrene copolymer, polyamide 6, polyamide 66 Polyamide resins such as polyamide 12 and polyamide 46, polyesters such as polycarbonate, polyacetal, PBT and PET, polyphenylene ether, polyphenylene sulfide, polyether ether ketone, polyallyl ether Illustrate ketene, polyamideimide, polyimide, polyetherimide, polysulfone, polyethersulfone, fluorine resin, polyurethane, ionomer, vinylidene chloride, chlorinated polyethylene, polydicyclopentadiene, methyl pen resin, polyacrylonitrile fiber resin, etc. Can do. Examples of the thermosetting resin include phenol resin, bisphenol A type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenyl type epoxy resin, naphthalene ring-containing epoxy resin, allylphenol novolac type epoxy resin, and fat. Cyclic epoxy resins, heterocyclic epoxy resins and epoxy resins such as their halides, polyurethane (for cast products), furan resins, unsaturated polyesters, melamine resins, urea resins, allyl resins (DAP), polyimide, silicon Resin (room temperature-containing curing) can be exemplified. Examples of the thermoplastic elastomer include polystyrene-based thermoplastic elastomers, polypropylene-based thermoplastic elastomers, polydiene-based thermoplastic elastomers, chlorine-based thermoplastic elastomers, engineering plastics-based elastomers, and the like.

  The polymer composition described in the present invention may or may not be crosslinked. When crosslinking, sulfur, organic peroxide, metal oxide, phenol resin, zinc oxide as vulcanization accelerator, stearic acid, vulcanization accelerator, vulcanization accelerator, polyfunctional acrylic monomer, etc. Any known co-crosslinking agent can be used. In the polymer composition described in the present invention, reinforcing agents, fillers, process oils, plasticizers, colorants, anti-shrink agents, and the like can be used as necessary. Examples of the reinforcing agent include carbon black, dry silica, wet silica, and fine particle boehmite. Fillers include heavy calcium carbonate, light calcium carbonate, colloidal calcium carbonate, kaolin clay, talc, mica, sericite, feldspar, calcium silicate, basic magnesium carbonate, aluminum hydroxide, magnesium hydroxide, natural silica, Examples thereof include bentonite and organic bentonite. These may be surface-treated with an organic acid such as fatty acid, resin acid, acrylic acid, silane coupling agent, titanate coupling agent, aluminum coupling agent and the like.

  The composite pyrolyzable foaming agent of the present invention is characterized by mixing the pyrolyzable foaming agent and the inorganic foaming promoting aid of the present invention.

  In the composite pyrolyzable foaming agent of the present invention, since the pyrolyzable foaming agent and the inorganic foaming promoting aid are mixed in advance, it can be easily added to a polymer or the like. In addition, since an inorganic foaming promoting aid can be mixed in advance at an optimum ratio with respect to the pyrolytic foaming agent, the size of the foamed cell can be foamed finely and uniformly at a high foaming ratio. The effect of the present invention can be obtained more effectively.

  The mixing ratio of the pyrolyzable foaming agent and the inorganic foaming promoting aid in the composite pyrolyzable foaming agent is the weight ratio described in the above-described ratio of the polymer composition of the present invention (pyrolytic foaming agent: inorganic foaming). Accelerator aid) is preferred.

  By using the inorganic foaming promoting aid of the present invention, the decomposition of the foaming agent can be promoted with a small amount of zinc, and the size of the foamed cell can be foamed uniformly and at a high foaming ratio. it can.

  According to the production method of the present invention, the inorganic foaming promoting aid of the present invention can be efficiently produced.

  Since the polymer composition of the present invention contains the inorganic foaming promoting aid of the present invention, the size of the foamed cells can be finely and uniformly foamed at a high foaming ratio.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a following example.

Example 1
In a plastic container equipped with a high-speed stirrer, 365.6% hydrochloric acid (2025.6 g) was added, and after adding 2.0 kg of ion-exchanged water, 813.9 g of zinc oxide (zinc oxide for rubber: two types of zinc white) was added and dissolved. . Furthermore, after adding 15.0 kg of ion-exchanged water, 740 g of a 45.0 wt% calcined kaolin slurry prepared in advance was added, and the mixture was stirred and dispersed for 20 minutes. Next, 5.0 kg of a 16.0 wt% aqueous sodium hydroxide solution was added over 60 minutes with stirring, and the mixture was stirred for 60 minutes after the addition was completed. Thereafter, the water washing steps of dilution, standing, and water cutting were repeated to perform sufficient water washing to obtain a calcined kaolin suspension carrying zinc oxide fine particles.

  The obtained calcined kaolin suspension was put into a plastic container equipped with a high-speed stirrer, and 3.20 kg of a 10% by weight aqueous ammonium hydrogen carbonate solution was added under high-speed stirring, followed by stirring for 10 minutes. Thereafter, heating was started at a temperature rising rate of 1 ° C./min, and the mixture was kept at 70 ° C. and stirred for 60 minutes.

  The obtained product was diluted with 5 times the amount of water, allowed to stand overnight and aged, and then the water was drained, and further the water washing steps of dilution, standing, and water cut were repeated to sufficiently wash with water. Thereafter, dehydration was performed, and the obtained paste was dried at 105 ° C., and pulverized with a pulverizer to obtain a calcined kaolin powder carrying basic zinc carbonate fine particles.

(Example 2)
A calcined kaolin carrying zinc oxide fine particles was carried out in the same manner as in Example 1 except that 2714.9 g of a 45.0 wt% calcined kaolin slurry was added and an aqueous sodium hydroxide solution was added in 1 minute. A suspension of was obtained. This suspension was dehydrated, and the resulting paste was dried at 105 ° C. and pulverized with a pulverizer to obtain a calcined kaolin powder carrying zinc oxide fine particles.

(Example 3)
A calcined kaolin carrying zinc oxide fine particles was carried out in the same manner as in Example 1 except that 2714.9 g of a 45.0 wt% calcined kaolin slurry was added and an aqueous sodium hydroxide solution was added in 1 minute. This was prepared and treated with an aqueous ammonium hydrogen carbonate solution in the same manner as in Example 1 to obtain a calcined kaolin powder carrying basic zinc carbonate fine particles.

(Example 4)
A calcined kaolin carrying zinc oxide fine particles was carried out in the same manner as in Example 1 except that 4936.2 g of a 45.0% by weight calcined kaolin slurry was added and an aqueous sodium hydroxide solution was added in 1 minute. A suspension of was obtained. This suspension was dehydrated, and the resulting paste was dried at 105 ° C. and pulverized with a pulverizer to obtain a calcined kaolin powder carrying zinc oxide fine particles.

(Example 5)
A calcined kaolin carrying zinc oxide was prepared in the same manner as in Example 1 except that 4936.2 g of a 45.0 wt% calcined kaolin slurry was added and an aqueous sodium hydroxide solution was added in 1 minute. This was treated with an aqueous ammonium hydrogen carbonate solution in the same manner as in Example 1 to obtain a calcined kaolin powder carrying basic zinc carbonate fine particles.

(Example 6)
A talc carrying zinc oxide was prepared in the same manner as in Example 1 except that 1110.0 g of a 30.0 wt% talc slurry was added and an aqueous sodium hydroxide solution was added over 40 minutes. This was treated with an aqueous ammonium hydrogen carbonate solution in the same manner as in Example 1 to obtain talc powder carrying basic zinc carbonate fine particles.

(Example 7)
In a plastic container equipped with a high-speed stirrer, 10.0 kg of a 8.0 wt% sodium hydroxide aqueous solution was added, 333.0 kg of wollastonite powder was added, and the mixture was stirred and dispersed for 20 minutes to prepare a wollastonite slurry. Subsequently, 813.9 kg of zinc oxide was dissolved in 2025.6 kg of 36.0% by weight hydrochloric acid, and ion-exchanged water was added to prepare an acidic aqueous solution prepared in advance to a total amount of 6.0 kg. Was added over 15 minutes. Except for this, wollastonite carrying zinc oxide was prepared in the same manner as in Example 1, and this was treated with an aqueous ammonium hydrogen carbonate solution in the same manner as in Example 1 to obtain basic zinc carbonate fine particles. A supported wollastonite powder was obtained.

(Comparative Example 1)
In a plastic container equipped with a high-speed stirrer, 365.6% hydrochloric acid (2025.6 g) was added, and after adding 2.0 kg of ion-exchanged water, 813.9 g of zinc oxide (zinc oxide for rubber: two types of zinc white) was added and dissolved. . Further, after 15.0 kg of ion-exchanged water was added for dilution, 5.0 kg of a 16.0 wt% aqueous sodium hydroxide solution was added over 1 minute, and the mixture was stirred for 60 minutes after the addition was completed. Thereafter, the water washing process of dilution, standing, and water-cutting is repeated, and after sufficiently washing with water, dehydration is performed, the resulting paste is dried at 105 ° C., and this is pulverized with a pulverizer to obtain a zinc oxide powder Got.

  As described above, here, zinc oxide fine particles were prepared by mixing an acidic aqueous solution of a zinc salt and an alkaline aqueous solution without adding a slurry of calcined kaolin.

[Measurement of BET specific surface area]
The BET specific surface area was measured about the inorganic type foaming acceleration | stimulation adjuvant of Examples 1-7 according to this invention obtained as mentioned above, and the zinc oxide of the comparative example 1. FIG. The BET specific surface area was measured by a flow type specific surface area measuring device manufactured by Micromeritec.

  For comparison, the BET specific surface area was also measured for the following commercially available zinc oxide powders.

Zinc flower 2 types: Zinc oxide for rubber manufactured by commercially available French method Composite zinc flower: Commercial product of calcium carbonate coated with zinc oxide Active zinc flower: For latex products and transparent rubber manufactured by wet method Commercially available zinc oxide fine particles Further, Table 1 shows the Zn equivalent weight of supported zinc oxide fine particles or basic zinc carbonate fine particles, the weight of anhydrous aluminum silicate mineral particles, and Al ₂ O _{3 in} anhydrous aluminum silicate mineral particles. The molar ratio of the Zn ratio (Zn / Al ₂ O ₃ ) in the zinc oxide fine particles or the basic zinc carbonate fine particles, and the supported amount in terms of Zn are also shown.

  Example 1, Example 3 and Example 5 are calcined kaolin particles carrying basic zinc carbonate fine particles. It can be seen that the BET specific surface area is higher than those in Examples 2 and 4 in which zinc oxide fine particles are supported.

  Moreover, it turns out that the inorganic type foaming acceleration | stimulation adjuvant according to this invention has a high BET specific surface area compared with the composite zinc white which is the calcium carbonate coat | covered with the zinc oxide.

[Measurement of decomposition temperature and generation amount of decomposition gas]
As a powder sample for measurement, the powder obtained in Examples 1 to 7 and Comparative Example 1 as well as two types of zinc oxide and composite zinc were used with respect to 1.0 g of organic pyrolytic foaming agent ADCA (azodicarbonamide) powder. A mixed powder prepared by adding 0.83 g of flower and active zinc flower powder and mixing well was used. About 1 g of this mixed powder was taken in a firing boat and precisely weighed, inserted into a test tubular glass tube, and set in the center of a tubular furnace serving as a heating portion of the cracked gas generation amount measuring device. Next, after connecting the glass tube and the generated gas amount measuring section, heating is performed at a heating rate of 5 ° C./min, and the temperature change in the sample section and the volume change in the glass tube are measured to determine the decomposition temperature of the sample. And the generation amount of decomposition gas (ml / g. Blowing agent) was determined. The measurement results are shown in Table 2.

  It can be seen that Examples 1 to 7 have a lower decomposition temperature and a higher generation amount of decomposition gas than Comparative Example 1 and two types of zinc white, composite zinc white, and activated zinc white.

[EVA formulation test]
Examples 1 to 5 and Comparative Example 1 as well as two types of zinc white, composite zinc white, and active zinc white were blended in EVA (ethylene-vinyl acetate copolymer resin) to prepare an EVA foam.

  ADCA was used as the foaming agent. The blending ratio is as shown below and specifically shown in Table 3.

EVA resin [manufactured by Tosoh Corporation, Ultrasen 630] 100.0 parts by weight Foaming agent ADCA [manufactured by Sankyo Kasei Co., Ltd., Cellmic-C] 4.0 parts by weight Foaming acceleration aid 0.5-2. 0 part by weight Stearic acid {reagent grade 1} 1.0 part by weight Crosslinker [manufactured by Sanshin Chemical Co., Ltd., Perhexa 3M] 1.0 part by weight filler [manufactured by Tokuyama Corporation, magnesium carbonate TT] 10.0 Part by weight While kneading the EVA resin with a roll, the above-mentioned various blending materials were added, and kneaded and dispersed after the addition. The obtained foam composition was set in a mold and subjected to press foaming at 160 ° C. for 30 minutes to obtain a foam molded article.

  The obtained foamed molded product was measured for specific gravity, and the results are shown in Table 3.

  Moreover, volume expansion ratio was calculated | required by the following formula | equation about the obtained foaming molding.

Volume foaming ratio = [(volume of foam cm ³ ) / (volume of mold = 93.6 cm ³ )] × 100
Further, the cross section of the obtained foamed molded article was observed, the number of bubbles having a diameter of 0.2 mm or more present per 1 cm ^{2 of} the cross section was measured, and the number was evaluated as the uniformity of the foam cross section.

  FIG. 1 is a photograph showing a cross section of the foamed molded product of Example 8, and FIG. 2 is a photograph showing a cross section of the foamed molded product of Comparative Example 2. As shown in FIG. 2, in the foamed molded article of Comparative Example 2, since foaming is not uniform, large bubbles are recognized. On the other hand, as shown in FIG. 1, in the foamed molded product of Example 8, large bubbles as observed in FIG. 2 do not exist, and foamed uniformly.

  As shown in Table 3, in Examples 8 to 12 using the foaming promotion aids of Examples 1 to 5 according to the present invention, the uniformity of the foam cross-section is all 0 and the foam is uniformly foamed. I understand that. On the other hand, in Comparative Examples 2-5, uniform foaming is not obtained. In particular, in Comparative Example 2 using the zinc oxide of Comparative Example 1, a relatively high foaming ratio is obtained, but it can be seen that foaming is not uniform. In Comparative Example 3 using two types of commercially available zinc white, Comparative Example 4 using commercially available composite zinc white, and Comparative Example 5 using commercially available zinc white, the expansion ratio is low and the foaming is not uniform. I know that there is.

[EPDM formulation test]
As shown in Table 4, the foam promoting aids according to the present invention of Examples 1, 4 and 5 and the zinc oxide, two types of zinc white, composite zinc white, and active zinc white of Comparative Example 1 were used. Using this, a blending test with EPDM was conducted.

  While roll-kneading EPDM (ethylene propylene diene rubber), compounding materials other than the foam accelerating aid shown in Table 4 were added to prepare a master batch.

  Next, to the master batch corresponding to 100 parts by weight of EPDM, a foaming rubber composition sheet is prepared by adding the foaming promotion aid shown in Table 4 under roll kneading so as to have the blending amount shown in Table 4. did.

  The obtained foamed rubber composition sheet was press vulcanized at 170 ° C. for 30 minutes to obtain an EPDM foamed rubber sheet.

  The resulting EPDM foam rubber sheet was measured for specific gravity, and the results are shown in Table 4.

  Further, the volume expansion ratio of the obtained EPDM foam rubber sheet was determined in the same manner as described above, and the results are shown in Table 4.

  Moreover, the compression strain was measured about the obtained EPDM foamed rubber sheet. The compressive strain was obtained by compressing a foamed molded article having a thickness of 9.53 mm to a thickness of 7.62 mm and holding it for 10 hours at room temperature, then releasing it, and measuring the thickness after 1 hour of opening. Table 4 shows the measurement results.

  As is clear from the results shown in Table 4, in Examples 13 to 15 in which the foaming promotion assistants of Examples 1, 4 and 5 according to the present invention were blended, the specific gravity was small and the volume foaming ratio was high. . In addition, since the compressive strain is small, it can be seen that a uniform foam is obtained.

  On the other hand, in Comparative Examples 6-9, it turns out that the specific gravity is large and volume expansion ratio is low. Moreover, in the comparative example 10, although it mix | blends so that the quantity of active zinc white may be less than the comparative example 9, the specific gravity of a foam becomes small and the volume foaming ratio is high. This is considered to be because vulcanization was suppressed by reducing the amount of zinc oxide as a vulcanization accelerator. However, the compressive strain has a large value, and it can be seen that foaming is uneven in a state where large bubbles are included.

  On the other hand, in Examples 13 to 15 according to the present invention, foaming is performed in a state where the volume foaming ratio is high and the compressive strain is small, the foam cell size is fine and uniform, and a high foaming ratio is foamed. You can see that

  Further, as is clear from the comparison between Examples 14 and 15 and Comparative Example 10, in the examples according to the present invention, the amount in terms of Zn is at least sufficiently vulcanized, and the inorganic foam of the present invention. It can be seen that the accelerator aid is also effective as a vulcanization accelerator.

  Further, in the above examples, the pyrolyzable foaming agent and the inorganic foam promoting aid of the present invention are separately added to the rubber, but the pyrolyzable foaming agent and the inorganic foam of the present invention are previously added. It has been confirmed that the effects of the present invention similar to or better than those of the above-described embodiments can be obtained even when an accelerator aid is mixed and added to rubber as a composite pyrolytic foaming agent.

  As described above, by using the inorganic foaming promotion aid of the present invention, the decomposition of the foaming agent can be promoted with a small amount of zinc, and the size of the foamed cell is finely uniform and at a high foaming ratio. Can be foamed.

The photograph which shows the cross section of the foaming molding of Example 8 using the inorganic type foaming promotion adjuvant of Example 1 according to this invention. The photograph which shows the cross section of the foaming molding of the comparative example 2 using the foaming promotion adjuvant of the comparative example 1. FIG.

Claims (13)

An inorganic foaming accelerating aid that accelerates the decomposition of the pyrolytic foaming agent,
An inorganic foaming accelerating aid characterized in that zinc oxide fine particles or basic zinc carbonate fine particles are supported on the surface of silicate particles.   The inorganic foaming promoting aid according to claim 1, wherein the supported amount of zinc oxide fine particles or basic zinc carbonate fine particles is in the range of 6 to 75% by weight in terms of metallic zinc. The inorganic foaming promotion aid according to claim 1 or 2, wherein the silicate particles supporting the zinc oxide fine particles have a BET specific surface area in a range of 10 to 55 m ² / g. The inorganic foaming promoting aid according to claim 1 or 2, wherein the silicate particles supporting the basic zinc carbonate fine particles have a BET specific surface area in a range of 25 to 90 m ² / g.   The inorganic foam promotion auxiliary agent according to any one of claims 1 to 4, wherein the silicate particles are aluminum silicate salt mineral particles.   6. The inorganic foaming accelerating aid according to claim 5, wherein the aluminum silicate salt mineral particles are anhydrous aluminum silicate salt mineral particles.   The inorganic foam accelerating aid according to claim 6, wherein the anhydrous aluminum silicate mineral particles are obtained by firing at least one selected from kaolinite, halloysite, pyrophyllite, and sericite.   The inorganic foaming promotion auxiliary agent according to any one of claims 1 to 7, wherein the pyrolytic foaming agent is an organic pyrolytic foaming agent. A method for producing the inorganic foaming promotion auxiliary agent according to any one of claims 1 to 8,
Preparing an acidic aqueous solution of zinc salt;
In the presence of silicate particles, an acidic aqueous solution and an alkaline aqueous solution of the zinc salt are mixed to precipitate zinc oxide fine particles or basic zinc carbonate fine particles, and zinc oxide fine particles or basic zinc carbonate are deposited on the surface of the silicate particles. A process for supporting fine particles, and a method for producing an inorganic foaming accelerating aid.   Process of converting silicate particles carrying zinc oxide fine particles with aqueous ammonium salt solution and converting the supported zinc oxide fine particles into basic zinc carbonate fine particles to form silicate particles carrying basic zinc carbonate fine particles. The method for producing an inorganic foaming promotion auxiliary agent according to claim 9, further comprising:   A composite pyrolyzable foaming agent, comprising a mixture of a pyrolyzable foaming agent and the inorganic foaming promoting aid according to any one of claims 1 to 8.   A polymer composition comprising a thermally decomposable foaming agent and the inorganic foam promoting aid according to any one of claims 1 to 8.   13. The polymer composition according to claim 12, wherein the content of the inorganic foaming promotion auxiliary is 0.5 to 20 parts by weight with respect to 100 parts by weight of the polymer.