JPH07316333A - Polypropylene-based resin internal-mold-expanded molding excellent in resistance to deterioration by metal - Google Patents

Abstract

PURPOSE:To obtain a polypropylene-based resin internal-mold-expanded molding excellent in resistance to deterioration by metal, stable for a long period of time and free from deterioration.even when used in a state in which it is in contact directly with a metal. CONSTITUTION:This is an internal-mold-expanded molding of polypropylene- based expansible resin particles composed of a base resin containing a metal- inactivating agent in an amount of 0.01 to 5 pts.wt. based on 100 pts.wt. polypropylene-based resin. The characteristics of this polypropylene-based resin internal-mold-expanded molding are that the resin constituting this expanded molding has a crystal structure showing two or more fusion peaks and the highest temperature fusion peak at 5 to 30J/g in measurement by a differential scanning calorimeter while raising the temperature at 10 deg.C/min rate of temperature rise up to 220 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene-based resin in-mold foam molded article, and in particular, the foam molded article obtained according to the present invention is used for a long period of time in a state of contacting a metal in a high temperature atmosphere. However, it does not change its properties and is excellent in metal deterioration resistance, and is effectively used as a heat insulating material, a structural member, an automobile part, a rug, a cushioning wrapping material, a float, a container and the like.

[0002]

BACKGROUND OF THE INVENTION Polypropylene resin foam moldings are used as various heat insulating materials for vehicle ceilings, pipe covers, etc. by utilizing their excellent heat resistance and heat insulating properties. . However, the polypropylene resin used as a base material is deteriorated when it is brought into contact with a metal in a high temperature atmosphere for a long period of time, and thus is not currently used for the purpose of contacting the metal at a high temperature.

On the other hand, when the present inventors have added a metal deactivator, which is generally used for preventing metal deterioration, to the polypropylene resin, the deterioration preventing effect does not appear as expected. Moreover, when a large amount of the metal deactivator is added, such an additive acts strongly as a cell nucleating agent and remarkably reduces the cell diameter of the foamed particles.
They faced the problem that the moldability in the mold deteriorates and the heat insulating property of the foamed molded product deteriorates.

[0004]

Therefore, the present inventors have
As a result of solving the above-mentioned problems and studying a heat insulating member that is stable for a long period of time even in contact with a metal while maintaining excellent heat resistance and heat insulating properties of a polypropylene resin in-mold foamed product, a polypropylene resin An in-mold foam molded article of polypropylene-based resin expanded particles comprising a base resin containing 0.01 to 5 parts by weight of a metal deactivator per 100 parts by weight, wherein the resin constituting the foam molded article is It has a crystal structure in which two or more melting peaks appear when measured with a scanning calorimeter at a temperature rising rate of 10 ° C./min up to 220 ° C., and the calorific value of the highest melting peak is 5 to 3
The present invention has been completed by using a polypropylene resin in-mold foam molded product having an amount of 0 J / g.

That is, in the present invention, the metal deactivator is added to 100 parts by weight of the polypropylene resin used for foaming.
A resin containing 01 to 5 parts by weight is used as a base resin. The amount is preferably 0.10 to 4 parts by weight, and if the amount added is too small, no sufficient effect is obtained, and if the amount added is too large, not only the improvement in the effect commensurate with that is not observed, but also the heat insulating property is reduced, which is not preferable. .

As the metal deactivator used in the present invention, conventionally known compounds can be used. For example, distearyl hydrazine, dilauroyl hydrazine, dicaproyl hydrazine, dioctanoyl hydrazine, bis-N, N '(2-ethylhexanoyl) hydrazine, sarcidol-benzoyl hydrazine, salicylidene salicyloyl hydrazine (manufactured by Ciba Geigy Ltd. , Trade name Chel-180], N, N'-bis [3- (3,5-
Di-t-butyl-4-hydroxyphenyl) propionyl] hydrtedin [Ciba-Geigy, trade name IRGAN
OX MD1024] and other hydrazine compounds and oxalo-bis-12-hydroxybenzylidene hydrazide [Eastman Kodak Company, trade name Eastman Inhibitor OABH], bis-salicyloyl (β, β ′).
-Thiodipropionic acid) hydrazide, isophthalic acid bis (α-phenoxypropionyl) hydrazide, bis-acetoadipic acid hydrazide [Ciba Geigy, trade name GI09-367], decamethylenedicarboxylic acid disalicyloyl hydrazide [Adeka Argus And hydrazide compounds such as trade name Adecastab CDA-6], benzotriazole, 3-amino-1,2,4-triazole, 1,3-diphenyltriazine, 5-phenyltetrazole, 3- (N-salicyloyl) amino. -1, 2,
Examples thereof include nitrogen-containing aromatic compounds such as 4-triazole [Adeka Stubb CDA-1 manufactured by ADEKA ARGUS CORPORATION] and the like, and these are used alone or in combination.

In the present invention, together with the metal deactivator, known antioxidants, light stabilizers, slip agents, antiblocking agents, ultraviolet absorbers, antistatic agents, pigments, inorganic fillers, dyes, etc. Can be added as required. The addition amount of them can be set according to the required function, but in general, polypropylene resin 1
The total amount of the additives excluding the metal deactivator is 0.01 to 10 parts by weight with respect to 00 parts by weight.

In the present invention, as a method of incorporating the metal deactivator into the polypropylene resin, there are a melt kneading method, a heat impregnation method, a melt coprecipitation method and the like, but the melt kneading method is the most general and preferable. For example, the polypropylene resin is heated and melted by a kneader such as an extruder, a Banbury mixer, and a mixing roll, and a metal deactivator is added and kneaded to uniformly disperse the resin in the resin. When the metal deactivator is uniformly dispersed, the resin is made into particles by various known methods. For example, strand cutting method, underwater cutting method,
Any method such as a hot cut method, a sheet cut method, a freeze pulverization method, a suspension dispersion method, and a melt spraying method may be used.

In the present invention, the polypropylene resin includes propylene homopolymer, propylene-
Ethylene random copolymer, propylene-butene-1 random copolymer, propylene-ethylene-butene-1 random copolymer, propylene-hexene-1 random copolymer, propylene-ethylene block copolymer, propylene-butene- In addition to an isotactic resin such as a one-block copolymer, a polypropylene resin having a syndiotactic structure can be used. Further, this polypropylene-based resin may be used in combination with other resin, rubber or the like within a range not impairing the characteristics of the polypropylene-based resin. Examples thereof include polyethylene resin, polybutene-1, ethylene-propylene rubber, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-isoprene block copolymer, and the like. 100 parts by weight of polypropylene resin is 100 parts by weight. It is possible to mix less than part, preferably less than 50 parts by weight.

In the present invention, the melting point of the preferred resin is
A resin having a melting peak temperature of 130 to 160 ° C. when it is measured by a differential scanning calorimeter is preferable. The resin has a melt flow index of 0.5 to 50 g / 10 minutes according to JIS K7210 and a load of 2.16 kg, more preferably 2
~ 20 g / 10 minutes.

In the present invention, the expanded particles are produced by the Docan method (Patent Office, March 63, Illustrated IPC) or the extrusion foaming method (JP-A-58-76230). For example, in the case of the Docan method, the base resin particles obtained above are dispersed in water in a closed container, a volatile expansion agent is supplied into the closed container, and the dispersion liquid is heated to a temperature equal to or higher than the softening point of the resin particles. After heating, the discharge port provided below the water surface in the closed container is opened, and the water dispersion liquid containing the resin particles impregnated with the expansion agent is discharged to the atmosphere (atmospheric pressure) lower than the pressure in the closed container. It is manufactured by At this time, it is preferable to pressurize the inside of the container with air or nitrogen gas to facilitate the discharge.

Examples of volatile swelling agents include aliphatic hydrocarbons such as butane, pentane, hexane, heptane, trichlorofluoromethane, dichlorofluoromethane, tetrachlorodifluoroethane, dichlorotetrafluoromethane, methylene chloride, ethyl chloride and the like. The halogenated hydrocarbons may be used alone or in combination of two or more. Further, it is also possible to use inorganic gases such as air, nitrogen gas and carbon dioxide gas. The addition amount of the volatile expansion agent varies depending on the type of the expansion agent and the intended bulk density of the resin particles, but is usually 10 to 80 parts by weight with respect to 100 parts by weight of the resin particles.

As the dispersant for dispersing the resin particles in water, aluminum oxide, titanium oxide, calcium carbonate,
Inorganic suspension agents such as basic magnesium carbonate and tribasic calcium phosphate, polyvinyl alcohol, methyl carboxycellulose, water-soluble polymeric protective colloid agents such as N-polyvinylpyrrolidone, sodium dodecylbenzene sulfonate, sodium alkane sulfonate, alkyl Examples thereof include anionic surfactants such as sodium sulfate ester, sodium olefin sulfate ester, acylmethyl taurine, and sodium dialkylsulfosuccinate.

To a water dispersion of polypropylene resin particles dispersed in water with a dispersant, a gaseous or liquid swelling agent is supplied in a closed container, so that the softening point of the resin or higher,
Preferably, the resin is heated to a temperature around the above-mentioned melting peak temperature, and the pressure in the container is raised by this heating, and the expander is impregnated into the resin particles. Then, polypropylene resin foam particles are obtained by discharging the resin particles together with water into a low pressure region (generally at atmospheric pressure) from a discharge port such as a slit or a nozzle provided in the lower part of the closed container.

Various conventionally known methods can be used as the molding method. A. After the foamed particles are pre-impregnated with a volatile liquid expander to give the foamed particles a secondary foaming ability, they are filled in a mold and heated with steam to cause secondary foaming and fusion of the foamed particles,
Then, the mold is cooled to obtain a formed body. B. Put the foamed particles in a closed container, then air, inorganic gas such as nitrogen is pressed into the container to increase the pressure in the cells of the expanded particles to give a secondary foaming ability, and the particles are filled in a mold, A method of heating by steam for secondary foaming and fusing particles, and then cooling the mold to obtain a molded body (pressure aging method, Japanese Patent Publication No. 59-23731). C. The foamed particles were placed in a mold whose pressure was increased to 1.0 to 6.0 kg / cm ² G with a pressurized gas, and 0.5 kg / cm ² from the mold.
While compressing using the above-mentioned high pressurized gas, it is divided into a plurality of times and sequentially filled, the mold pressure during filling is kept at the mold pressure described above, and then the mold pressure is returned to atmospheric pressure after the completion of filling. Then heat with steam to fuse the expanded particles, the formula of the expanded particles at that time,

[0016]

[Equation 1] A method of controlling the compression ratio represented by the above to 40 to 70% and then cooling the mold to obtain a molded body (Japanese Patent Laid-Open No. 62-15132).
No. 5).

D. 0.5-5.0 kg / cm with pressurized gas
^In the mold boosted to ² G, 0.5 k from the mold pressure in advance
The expanded particles to which a gas internal pressure is obtained, which are obtained by pressurizing the gas for 1 hour or more using a pressured gas higher than g / cm ^{2, are} higher than the pressure inside the mold by 0.5 kg / cm ² or higher. Using the above, it is divided into a plurality of times and sequentially filled, and during filling, the in-mold pressure is kept at the above-mentioned in-mold pressure, and after completion of the filling, the in-mold pressure is returned to atmospheric pressure and then heated by steam. A method in which expanded particles are fused and the compression ratio of the expanded particles represented by the above formula is controlled to less than 40% (excluding 0%), and then the mold is cooled to obtain a molded product.

E. Expanded particles themselves are filled with expanded particles having secondary expansion ability in the cavity under normal pressure, or filled in a mold under pressure and heated by steam for secondary expansion and fusion of the expanded particles, then , A method of cooling the mold to obtain a molded body (Japanese Patent Laid-Open No. 62-128709).
JP-A-63-256634, JP-A-63-25893
No. 9, JP-A-63-107516). Any of the above molding methods may be used, and the molding method is selected in consideration of the properties of the expanded particles, the shape of the molded body, the density and the like.

In the present invention, the resin constituting the polypropylene resin in-mold foamed article has two melting peaks when measured with a differential scanning calorimeter at a temperature rising rate of 10 ° C. to 220 ° C. It has the crystal structure that appears above, and the calorific value (ΔH) of the melting peak at the highest temperature is 5 to 5.
It needs to be 30 J / g. This ΔH is 30J
If the amount is more than 1 g / g, even if the metal deactivator is contained in the polypropylene resin in the above-mentioned specified amount, the effect is hardly exhibited and it is uneconomical. Is fine, the heat insulating property is lowered, and the moldability is impaired. On the other hand, when the amount is less than 5 J / g, the effect of the metal deactivator is exhibited well, but the surface smoothness, mechanical properties, heat insulating properties and the like of the foamed molded product are deteriorated and the inside of the mold from the foamed particles is deteriorated. It is not preferable because the processability of the foamed molded product is significantly deteriorated.

In the present invention, ΔH can be adjusted by the combination of the type of resin used and the foaming process. For example, when producing expanded particles by foaming docan,
It is adjusted by holding for a certain period of time under a condition of being higher than the softening point of the polypropylene resin used and lower than the temperature at which all the crystals disappear. Generally retention time is 5 minutes to 12
It is about 0 minutes, and ΔH can be increased by holding it for a long time. In addition, the lower the holding temperature, the more
Since H becomes large, the optimum condition in the process is selected and ΔH is adjusted to the target range.

In the present invention, ΔH of the resin constituting the polypropylene resin in-mold foam molded article is adjusted to 5 to 30 J / g, and the foam molded article is measured at 30 ° C. according to JIS K6767, that is, The heat shrinkage rate is preferably 10% or less. If the heat shrinkage rate exceeds 10% and significantly shrinks, it is restricted to use in a high temperature atmosphere.
The functions of various additives tend not to be stably exhibited. Examples of the method for adjusting the heat shrinkage ratio within the preferred range of the present invention include a method in which the polypropylene resin used has high heat resistance and is adjusted by a foaming method or a molding method.

Further, as a method for further increasing the expansion ratio of expanded particles, a method of expanding in multiple stages (Japanese Patent Publication No. 2-5094).
No. 4, Japanese Patent Publication No. 2-50945, Japanese Patent Publication No. 3-64543
(Japanese Laid-Open Patent Publication) etc., and such a technique can be used in the present invention. However, in general, a polypropylene-based resin in-mold foam molded product obtained by using multi-stage expanded particles has a large strain on the cell wall due to the foaming process from the second stage onward and heat shrinkage of the molded product. In the present invention, in the case of foaming in multiple stages, the ratio after the second stage is 1.5 because the problem that the rate becomes large easily occurs.
It is preferable to suppress the foaming ratio to twice or less.

Hereinafter, the present invention will be described in more detail with reference to examples. The parts and% in the examples are based on weight.

[0024]

【Example】

(Example 1) A propylene-ethylene random copolymer having a bending rigidity of 8800 kg / cm ² measured according to JIS K7106 (ethylene content 2.5%, melting point 14
5 ° C., MFR 9 g / 10 min) 100 parts, calcium stearate 0.10 parts, 2,6-di-t-butyl-p-
Cresol [Product name Yoshinox BH manufactured by Yoshitomi Pharmaceutical Co., Ltd.
T] 0.05 part, tetrakis [methylene-3 (3 ',
5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane [trade name IR manufactured by Ciba-Geigy
GANOX 1010] 0.10 part, and N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine [trade name IRGANOX MD10 manufactured by Ciba-Geigy as a metal deactivator.
24] 0.20 parts was added, and the mixture was kneaded at 210 ° C. with a single-screw extruder having a diameter of 65 mm, extruded into a strand having a diameter of 1 mm, cooled in a water tank, and cut at a size of about 1.2 mg / grain. Then, resin particles were prepared. Subsequently, 250 parts of water, 100 parts of resin particles, 1.0 part of tricalcium phosphate, and sodium dodecylbenzenesulfonate of 0.
007 parts were charged (filling rate 62%), and then nitrogen gas was pressurized with stirring to 3 kg / cm ² G, and the supply of nitrogen gas was stopped. Then, 21.5 parts of butane was fed into the closed container, heated to 135 ° C. over 45 minutes, and kept at the same temperature for 15 minutes. The pressure inside the closed container was 21.
It showed 5 kg / cm ² G. Then, the valve of the discharge nozzle at the bottom of the closed container was opened, and the dispersion liquid was discharged into the atmospheric pressure to obtain expanded particles. The polypropylene resin expanded particles thus obtained have a bulk density of 24 g / l and a particle size of 3.5.
The average bubble diameter was 200 mm and the average bubble diameter was 200 μm.

The obtained expanded particles were subjected to 2 at 40 ° C. atmosphere.
After leaving for a day, the mold formed by a pair of concave and convex molds having steam holes was sequentially filled with compressed air of 2.2 kg / cm ² G, and then 3.0 kg / cm ² G The steam was introduced, the foamed particles were heated and fused, then cooled with water for 100 seconds and allowed to cool for 30 seconds, and the molded body was taken out from the mold. The molded product has a density of 40 g / l, a length of 600 mm, and a width of 9
The surface was 00 mm and the thickness was 50 mm, and the surface was smooth with few gaps between particles. In addition, when a cut was made at the center of the molded product with a knife at a depth of 10 mm and the cut was further pressed to widen and rupture, about 90% of the cross section of the foamed particle was an excellent molded product. there were. Thermal analysis of this molded product by DSC gave ΔH of 15 J.
/ G.

The heat shrinkage of this molded product, the metal deterioration resistance of the skin surface and the cut surface, and the surface smoothness were evaluated by the following methods. As a result, the heat shrinkage was -4.5%. The deterioration test was good after 200 hours with no change in both the molded skin surface and cross section, and the surface smoothness of the molded product was also excellent. Heating dimensional change rate: 5 after molding
150 mm long and 150 m wide from the molded body after 0 hours
m, 50 mm thick test piece was cut out and JIS K
According to 6767, heating was carried out for 22 hours in a gear oven at 130 ° C., and the average was evaluated.

Metal deterioration resistance: 100 mm in length from the molded body,
A test piece with a width of 100 mm and a thickness of 25 mm was cut out, and the outer diameter of the test piece was polished with sandpaper to obtain an outer diameter of 8 mm.
The φ copper pipe was scissored, placed in a gear oven at 120 ° C., and the deterioration state of the skin surface and the cross section in contact with the copper pipe at regular intervals was evaluated for each of 5 samples. ⊚: No change in all samples even after 200 hours.

◯: No change in the sample of 2/5 or less even after 200 hours. Δ: Samples of 2/5 or less did not change after 100 hours, but deterioration of samples exceeding 2/5 was observed after 200 hours. X: Deterioration of the sample exceeding 2/5 is recognized after 100 hours. Surface smoothness: The molded body was visually evaluated.

⊚: Surface is smooth with few gaps between particles. ◯: Surface is smooth although there are gaps between particles. Δ: There is a gap between particles, and the surface is uneven. X: The voids between the particles are significant, or the surface is significantly shrunk and has no commercial value. Thermal conductivity: Measured according to the flat plate comparison method of JIS A1412, and evaluated according to the following criteria.

⊚: 0.035 Kcal / mh ℃ or less. Δ: 0.040 to 0.036 Kcal / mh ° C ×: exceeds 0.040 Kcal / mh ° C. (Examples 2 to 6, Comparative Examples 1 to 5) Base resin of resin particles,
Example 1 was repeated except that the metal deactivator, foaming conditions, molding conditions, etc. were changed as shown in Table 1. The results are shown in Tables 1 to 3.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

* 1 N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine (trade name IRGANOX MD1 manufactured by Ciba-Geigy)
024) * 2 3- (N-salicyloyl) amino-1,2,4-
Triazole (product name ADEKA STAB CDA-1 manufactured by ADEKA ARGUS) * 3 Decamethylenedicarboxylic acid disalicyloyl hydrazide (product name ADEKA STAB, manufactured by ADEKA ARGUS)
CDA-6) * 4 Oxalobis-12-hydroxybenzylidene hydrazide (Eastman Kodak Co., Ltd. trade name Eastman Inhibitor OABH)

[0035]

EFFECT OF THE INVENTION The polypropylene resin foamed molded product of the present invention is excellent in metal deterioration resistance, and has an excellent effect that it is stable for a long period of time and does not deteriorate even when used as a heat insulating material in applications where it is in direct contact with a metal. .

Claims (2)

[Claims] 1. An in-mold foam molded article of polypropylene resin expanded particles comprising a base resin containing 0.01 to 5 parts by weight of a metal deactivator per 100 parts by weight of a polypropylene resin. The resin constituting the body has a crystal structure in which two or more melting peaks appear when measured with a differential scanning calorimeter at a temperature rising rate of 10 ° C./min up to 220 ° C. Calorific value of melting peak is 5-30
A polypropylene-based in-mold foam molded article having an excellent metal deterioration resistance, which is characterized by J / g. 2. The polypropylene resin in-mold foam molded article according to claim 1, which has a heat shrinkage of 10% or less when measured at 130 ° C. according to JIS K6767.