JPH0212257B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to azodicarbonamide (hereinafter referred to as
Abbreviated as ADCA. ) as a blowing agent. So-called chemical blowing agents that decompose upon heating to generate gas are widely used as blowing agents for thermoplastic resins. Among these, ADCA is used because it generates a large amount of gas per unit mass, the gas generated is relatively odorless, the decomposition residue is non-toxic, odorless, and non-migratory, and it has good storage stability. It is widely used as a blowing agent for various thermoplastic resins, including polyvinyl chloride, polyethylene, and polypropylene. However, ADCA has a high decomposition temperature of approximately 200°C, so when it is used for foaming thermoplastic resins, the decomposition temperature of the blowing agent is higher than the softening point of these resin materials, so ADCA has traditionally been combined with foaming aids. The decomposition temperature is adjusted to a low temperature side by using the decomposition temperature in combination with the decomposition temperature. Urea, fatty acid metal salts, zinc oxide, and the like are known as such auxiliaries. When foam-molding olefin resins by extrusion molding, blow molding, or inflation molding, olefin resins have lower elasticity when melted than other thermoplastic resins such as polystyrene, and Because the temperature sensitivity ratio is large, the range of extrusion processing conditions is extremely narrow, which is a factor in reducing the yield of molded products. In addition, the above foaming aid can lower the decomposition temperature of ADCA, but the decomposition rate of ADCA is rapid;
In addition, since a high decomposition heat of about 10 Kcal/Mol is generated during decomposition, it has been extremely difficult to obtain a foam having fine and uniform cells. Therefore, the present inventors focused on an auxiliary agent that lowers the decomposition temperature, slows down the decomposition rate, and suppresses the amount of heat of decomposition without affecting the amount of gas generated by ADCA. Formula [Ar(SO ₃ ) _o ] _n
M (wherein Ar represents a group having an aryl skeleton, M is a hydrogen atom, NH ₄ , or Li, Na,
K, Mg, Ca, Sr, Ba, Zn, Cd, Sn and Pb
represents a metal selected from the group consisting of, n and m are integers. ) (hereinafter abbreviated as aryl sulfonate) satisfies the above requirements as a foaming aid, has a wide range of optimal extrusion processing conditions, and has a fine and uniform cell structure. The present invention was achieved based on the findings that the foaming agent is effective in obtaining foaming foams and that the extrusion rate is increased by about 20% compared to conventional foaming aids. That is, the present invention provides a polyolefin composition containing ADCA as a blowing agent, in which one or two aryl sulfonates are added to 1 part by weight of the blowing agent.
The object of the present invention is to provide a polyolefin composition for foam molding containing 0.05 to 2 parts by weight of at least one of the following. Examples of the arylsulfonate that can be used in the present invention include benzenesulfonate, benzene disulfonate, toluenesulfonate, toluene disulfonate, xylene sulfonate,
Examples include butylbenzenesulfonate, dodecylbenzenesulfonate, naphthalenesulfonate, naphthalene disulfonate, among others, ammonium dodecylbenzenesulfonate, potassium dodecylbenzenesulfonate, zinc dodecylbenzenesulfonate, barium naphthalenesulfonate. etc. are often used. Therefore, M of the arylsulfonate represented by the above general formula is H, _NH4 , and
Although there are some differences in the thermal stability of the aryl sulfonate itself and in the bubble state of the resulting molded product due to the above-mentioned differences in metals, the present invention
Regarding the foaming aid effect of ADCA, almost the same effect can be obtained. Examples of the polyolefin include known olefin resins that can be used for foam molding by extrusion molding, blow molding, inflation molding, etc., such as polyethylene, polypropylene, ethylene-propylene copolymers alone and mixtures of olefin resins. Alternatively, any mixture of olefin resin as a main component and other thermoplastic resins such as polystyrene and rubber can be used. Further, foam molding may be carried out while or after crosslinking the olefin resin with a crosslinking agent. The amount of ADCA added to the polyolefin can be within the range of 0.1 to 10 parts by weight. The aryl sulfonate used in the present invention may be used as a mixture with a so-called dispersant such as polyethylene glycol or polyethylene glycol monomethyl ether without causing any practical problems, but the ratio of the aryl sulfonate used is based on 1 part by weight of ADCA. te 0.05~2
Good results are obtained by adding 0.2 to 1 part by weight, preferably 0.2 to 1 part by weight. Therefore, if the amount added is less than 0.05 parts by weight, ADCA
It is not effective in lowering the decomposition temperature, decomposition rate, and decomposition heat value, and if it exceeds 2 parts by weight, the bubbles in the foamed molded product become uneven and the surface condition deteriorates, which is not preferable. When using the polyolefin composition of the present invention, ADCA and aryl sulfonate may be kneaded into the polyolefin separately or together in advance and adjusted to a predetermined ratio before use. However, they may also be used directly as a simple mixture without kneading the three components. In addition, commonly used pigments, antioxidants, lubricants, antistatic agents, weather resistance improvers, fillers, etc. can be appropriately used in the polyolefin composition of the present invention within well-known amounts. The composition can be made into a foam molded article by employing commonly used extrusion molding methods, blow molding methods, inflation molding methods, and molding conditions. The polyolefin composition for foam molding prepared by adding the foaming aids aryl sulfonate and ADCA to polyolefin according to the present invention has a wider range of optimal extrusion processing conditions and a higher throughput than the combination with conventional foaming aids. It increases by about 20%. Furthermore, a polyolefin foam having a fine and uniform cell structure and a beautiful surface can be obtained. The present invention will be further explained below with reference to Examples. Example 1 Dodecylbenzenesulfonic acid was added to 75 parts by weight of polypropylene pellets (trade name, manufactured by Mitsui Toatsu Chemical Co., Ltd., BJS-M) (MI, 1.5), 25 parts by weight of high-density polyethylene pellets (MI, 0.3). 0.2 parts by weight of a mixture of ammonium: polyethylene glycol monomethyl ether (molecular weight approximately 200) = 1:1 parts by weight (trade name, manufactured by Katsuta Kako Co., Ltd., TCV-711p) was sprinkled on the above pellets, and 0.17 parts by weight of ADCA was added. . The mixture was passed through a 65m/mφ extruder (screw rotation speed
40 rpm) by changing the extrusion conditions as shown in Table 1.
Foam molded. As shown in Table 2, the foam obtained under each extrusion condition (thickness: approx. 1.5m/width: approx. 380m/m) maintains a uniform microcellular structure even when the cylinder temperature of the extruder is changed by as much as 20℃. As shown, the range of optimal extrusion processing conditions was wide, and the cell diameter was even smaller than that of the comparative example below. Moreover, the extrusion amount was about 20% larger than that of the comparative example below. Example 2 In Example 1, the amount of TCV-711p added was 0.2
The extrusion conditions were changed as shown in Table 1, except that part by weight was changed to 0.1 part by weight, and the extrusion conditions were changed as shown in Table 2.
The extrusion result was as shown in . Examples 3 and 4 In Example 1, instead of TCV-711p, a mixture of potassium dodecylbenzenesulfonate: polyethylene glycol (molecular weight about 200) = 1:1 parts by weight (Example 3) and barium naphthalenesulfonate: polyethylene Glycol (molecular weight approximately 200)
EXAMPLES 3 and 4 were foam-molded in exactly the same manner except that 0.1 part by weight of the 1:1 part by weight mixture (Example 4) was used. Table 1 shows the extrusion conditions, and Table 2 shows the extrusion results. Example 5 Example 2 was carried out in exactly the same manner as in Example 1, except that 0.1 part by weight of a mixture of zinc dodecylbenzenesulfonate: polyethylene glycol monomethyl ether = 1:1 part by weight was added, and the extrusion conditions were as shown in Table 1. Foam molding was performed by changing the The extrusion results were as shown in Table 2. Comparative Examples 1 and 2 The same amounts of polypropylene pellets and high-density polyethylene pellets used in Example 1 were used, and the pellets were sprinkled with 0.1 part by weight of the same polyethylene glycol monomethyl ether or polyethylene glycol used in Example. ADCA
0.17 parts by weight was added. The mixture was foam-molded in exactly the same manner as in Example 1, with the extrusion conditions changed as shown in Table 1. As shown in Table 2, the obtained foam had large cells and a poor surface condition. Comparative Examples 3, 4, 5 The same amounts of polypropylene pellets and high-density polyethylene pellets used in Example 1 were used, and the same polyethylene glycol as used in Example was used.
Sprinkle 0.1 part by weight on the pellets, and apply urea (Comparative Example 3) and activated zinc white (trade name, KAI Kagaku Kogyo ZINCA).
#20) (Comparative Example 4) and 0.1 part by weight of aluminum stearate (Comparative Example 5) and 0.17 part by weight of ADCA were added and blended. The mixture was foam-molded in exactly the same manner as in Example 1, changing the extrusion conditions as shown in Table 1, and was used as Comparative Examples 3, 4, and 5. As shown in Table 2, in Comparative Examples 3 and 4, the foam was It was rough foam. Furthermore, in Comparative Example 5, when the cylinder temperature of the extruder was further increased by 10°C, the range of optimal extrusion processing conditions was narrowed, as the bubbles became larger. Comparative Example 6 The same amount of polypropylene pellets and high-density polyethylene pellets used in Example 1 were used, and the same polyethylene glycol as used in Example was used.
0.1 part by weight was sprinkled on pellets, and 2.0 parts by weight of barium naphthalene sulfonate and 0.17 parts by weight of ADCA were added and blended. In exactly the same manner as in Example 1, Table 1
Foam molding was carried out by changing the extrusion conditions as shown below. As shown in Table 2, the cells of the obtained foam were non-uniform, ranging from fine to coarse, and the surface condition was poor under the same extrusion temperature.

【table】

【table】

[Table] In the column of Table 2, the bubble diameters were classified as follows. Fine (less than 60μ), small (60-100μ), medium (100-200μ), large (200-400μ) and coarse (more than 400μ).

Claims (1)

[Scope of Claims] 1. In a polyolefin composition containing azodicarbonamide as a blowing agent, the general formula [Ar(SO ₃ ) _o ] _n M (wherein Ar is aryl) is added to 1 part by weight of the blowing agent. Represents a group having a skeleton, M is a hydrogen atom, NH ₄ , or Li, Na, K, Mg, Ca,
It represents a metal selected from the group consisting of Sr, Ba, Zn, Cd, Sn and Pb, where n and m are integers. ) One or more compounds represented by 0.05 to
A polyolefin composition for foam molding, characterized in that it contains within a range of 2 parts by weight.