JP2008143935A - Crosslinked polyethylene-based resin foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polyethylene-based resin foam that is suitably useful as a building thermal insulation material for roofs, has not too strong stiffness (force of repulsion), excellent flexibility and slipperiness, does not peel off from a substrate even in the case of use for a part of a fusion method using an adhesive and in the case of application to roofs having shapes of steep angles, and yet is easily handleable and has a surface to be hardly damaged. <P>SOLUTION: The resin composition obtained by mixing 100 parts by mass of a polyethylene-based resin with 0.15-3 parts by mass of a pentaerythrityl-tetrakis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)]propionate with 0.15-3 parts by mass of an antistatic agent is crosslinked and foamed by a chemical crosslinking foaming method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyethylene-based crosslinked foam, and more particularly to a polyethylene-based crosslinked foam excellent in flexibility and slipperiness.

  For building insulation for roofs, inorganic materials such as glass wool, sprayed asbestos and gypsum board, and various plastic foams such as foamed polyolefin, foamed polystyrene and foamed polyurethane are used. In particular, polyolefin resin cross-linked foams are widely used as architectural heat insulating materials for roofs because they are excellent in lightness, water resistance, weather resistance and chemical resistance. Among these, chemically crosslinked foams of polyethylene resins are stronger (repulsive force) and higher in surface strength than electron beam crosslinked foams. Since it has advantages such as excellent heat-fusibility, it is often used as a building heat insulating material for roofs (see, for example, Patent Document 1).

JP 59-62643 A

  However, the above-mentioned polyethylene resin chemically cross-linked foam has a stiffness (repulsive force) when using a partial fusing method using an adhesive or when applied to a roof with a sharp angle shape. It might be peeled off from the groundwork because it was too strong.

  The present invention has been made in view of the above-described circumstances, and is a polyethylene-based resin cross-linked foam suitably used as a building heat insulating material for roofs, which is not too strong (repulsive force), flexible and slippery. Even if some fusion methods using adhesives are used, or when applied to a roof with a steep angle shape, it does not peel off from the groundwork, and it is easy to handle, surface scratches, etc. Provided is a polyethylene resin cross-linked foam which is difficult to stick.

  The present inventors considered that the problem of peeling of the polyethylene resin chemically cross-linked foam could be solved by weakening the stiffness (repulsive force) of the polyethylene resin, and examined it. And in chemical cross-linking foaming, the characteristic of strong stiffness (repulsive force) is attributed to the fact that the degree of cross-linking near the surface is higher than the inside, and the cross-linking agent is used to make the cross-linking degree of the foam uniform. As a result of investigating the addition of an antioxidant that inhibits the reaction, it has been found that when a specific antioxidant is added, the stiffness (repulsive force) of the chemically crosslinked foamed polyethylene resin can be weakened. However, when the above specific antioxidant is added, a new problem that surface flaws occur in the foam during molding occurs. Therefore, by adding an antistatic agent to improve the slipping property, the above new problem is caused. It was found that can be solved.

  The present invention has been made based on the above findings, and pentaerythrityl-tetrakis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] with respect to 100 parts by mass of polyethylene resin. Provided is a polyethylene-based resin crosslinked foam obtained by crosslinking and foaming a resin composition containing 0.15 to 3 parts by mass and an antistatic agent 0.15 to 3 parts by a chemical crosslinking foaming method. .

  The polyethylene resin cross-linked foam of the present invention is not too strong (repulsive force) and has excellent flexibility and slipperiness. Therefore, when the polyethylene resin cross-linked foam of the present invention is used as a building heat insulating material for roofs, and when a part of the fusing method using an adhesive is used, or when applied to a roof having a steep angle shape In addition, it is possible to obtain an effect that the substrate is not peeled off, is easy to handle, and is hardly damaged by a surface.

  Hereinafter, the present invention will be described in more detail. The base resin of the resin composition for producing the polyethylene resin crosslinked foam of the present invention (hereinafter referred to as “the resin composition of the present invention”) is mainly composed of low density polyethylene (LDPE) or low density polyethylene. A mixture obtained by mixing ethylene vinyl acetate copolymer (EVA), linear low density polyethylene (LLDPE), or high density polyethylene (HDPE) can be preferably used.

  The resin composition of the present invention comprises pentaerythrityl-tetrakis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (hereinafter referred to as “component (A)”) as an essential component. Contained as. By foaming the resin composition containing the component (A) by the chemical crosslinking foaming method, the stiffness (repulsive force) of the foam can be weakened. As the component (A), commercially available products can be used, and examples thereof include Irganox 1010 (trade name, manufactured by Ciba Specialty Chemicals).

  The compounding quantity of (A) component in the resin composition of this invention is 0.15-3 mass parts, More preferably, it is 0.2-2.5 mass parts. If the amount of component (A) is too small, cracks may occur in the foam and the desired foaming ratio may not be obtained, or the molding performance may deteriorate, and (A) If the blending amount of the component is too large, problems such as cross-linking inhibition and poor foaming may occur.

  The resin composition of the present invention contains an antistatic agent as an essential component. By foaming a resin composition containing an antistatic agent by a chemical crosslinking foaming method, the effect of improving slipperiness and improving the susceptibility to scratching can be obtained. As the antistatic agent, a surfactant-based antistatic agent such as a nonionic surfactant-based antistatic agent, an anionic surfactant-based antistatic agent, or a cationic surfactant-based antistatic agent is preferably used. Can be used. Specific examples of the antistatic agent include an electron stripper (trade name, manufactured by Kao Corporation) and Elegan (trade name, manufactured by Nippon Oil & Fats Co., Ltd.). Among them, the use of elegance is preferable in terms of relative effect.

  The compounding quantity of the antistatic agent in the resin composition of this invention is 0.15-3 mass parts, More preferably, it is 0.2-2.5 mass parts. If the blending amount of the antistatic agent is too small, the slipperiness of the foam may be deteriorated. If the blending amount of the antistatic agent is too large, the adhesiveness of the foam may be a problem.

  In the present invention, a polyethylene resin cross-linked foam is obtained by blending the polyethylene resin with the component (A) and the antistatic agent, and further heating a resin composition containing a cross-linking agent and a foaming agent. be able to.

  In this case, a known crosslinking agent can be used as the crosslinking agent. For example, dicumyl peroxide, di-t-butyl peroxide and the like can be used, but the crosslinking agent is not limited thereto. More specifically, examples of the crosslinking agent include Park Mill D (trade name, manufactured by NOF Corporation).

  Moreover, as a foaming agent, a well-known thermal decomposition type foaming agent can be used, for example, azodicarbonamide, di-nitrosopentamethylenetetramine, etc. can be used, but it is not limited to these. More specifically, Uniform AZ (trade name, manufactured by Otsuka Chemical Co., Ltd.) and the like are exemplified as the foaming agent.

  The method for obtaining the polyethylene resin crosslinked foam of the present invention is not particularly limited as long as it is a generally used method for producing a chemically crosslinked foam. Specifically, for example, a predetermined amount of component (A), an antistatic agent, a crosslinking agent and a foaming agent are mixed with the low density polyethylene resin to produce a resin composition, and then the foaming agent and the crosslinking agent are decomposed. A method in which the resin composition is formed into a sheet by means such as extrusion molding at a temperature at which the foaming is not performed, and the obtained sheet is placed in a hot air oven set to a temperature at which the foaming agent and the crosslinking agent are decomposed, and foamed simultaneously with crosslinking. Etc.

  Next, although an example shows the present invention still more concretely, the present invention is not limited to the following example. In this example, foams of Examples 1 to 5 and Comparative Examples 1 to 6 shown in Tables 1 and 2 below were produced. In this case, 100 parts by weight of low density polyethylene (LDPE), 26 parts by weight of azodicarbonamide (decomposition temperature 187 ° C.) as a foaming agent, 0.7 parts by weight of dicumyl peroxide as a crosslinking agent, and oxidation After preparing a resin composition by melt mixing 0.1 to 5 parts by weight of the inhibitor X, Y or Z and 0.1 to 5 parts by weight of the antistatic agent, an extruder (L / D = 28, A sheet of a resin composition having a thickness of 2 mm was prepared using Φ = 40 m / m), and this sheet was put into a hot air oven at 230 ° C. to be crosslinked and foamed.

The following were used as antioxidants and antistatic agents. Tables 1 and 2 show the blending amounts of low-density polyethylene, antioxidant, and antistatic agent in each Example and Comparative Example.
Low density polyethylene: Trade name Novatec YF30, manufactured by Nippon Polyethylene Co., Ltd. Antioxidant X: Component (A) (phenolic antioxidant, trade name Irganox 1010, manufactured by Ciba Specialty Chemicals)
Antioxidant Y: Phosphorous antioxidant (trade name ADK STAB HP-10, manufactured by Asahi Denka Co., Ltd.)
Antioxidant Z: Phosphorous antioxidant (trade name ADK STAB PEP36, manufactured by Asahi Denka)
Antistatic agent: nonionic surfactant-based antistatic agent (trade name Elegan N-1100, manufactured by NOF Corporation)

Extrusion foamability, adhesion peeling performance, molding performance, and sliding performance of the foams of each Example and Comparative Example were evaluated. The evaluation criteria are as follows. The results are shown in Tables 1 and 2.
(Extrusion foamability)
○: There is no problem in extrusion foamability, and a foam having a good design magnification can be obtained.
X: There is a problem in extrusion foamability, and a foam having a good design magnification cannot be obtained.
(Adhesive peeling performance)
A 0.6 mm thick colored galvanized steel sheet heated to 110 ° C. was bonded with a foam and passed through a metal roll. After 30 minutes, it was peeled off with a finger, and the material fracture area was confirmed visually.
○: Material breakage area is 10% or less.
X: Material breakage area exceeds 10%.
(Molding performance)
The product with the foam attached to the steel sheet was passed through a metal forming machine, bent at 90 ° or more, and visually evaluated for breakage and peeling of the foam.
○: Cutting or peeling does not occur in the foam.
X: Cutting or peeling occurs in the foam.
(Sliding performance)
The steel sheet with the foam attached thereto was passed through a metal forming machine and bent at 90 degrees or more, and the presence or absence of damage to the foam was visually evaluated.
○: The foam is not damaged.
X: The foam is scratched.

  From Tables 1 and 2, a resin composition containing 0.15 to 3 parts by mass of component (A) as an antioxidant and 0.15 to 3 parts by mass of an antistatic agent for 100 parts by mass of a polyethylene resin. It can be seen that the foams of Examples 1 to 5 that were crosslinked and foamed had good extrusion foaming properties, adhesive peeling performance, molding performance, and sliding performance. On the other hand, the foam of Comparative Example 1 with a small amount of component (A) has poor molding performance, and the foam of Comparative Example 2 with a large amount of component (A) has poor extrusion foamability and is antistatic. The foam of Comparative Example 3 with a small blending amount of the agent has poor sliding performance, and the foam of Comparative Example 4 with a large blending amount of the antistatic agent has poor adhesion release performance, and Comparative Example 5 blended with a phosphorus antioxidant. , 6 had poor extrusion foamability.

Claims (2)

  Pentaerythrityl-tetrakis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] 0.15-3 parts by mass, antistatic agent 0.15 with respect to 100 parts by mass of polyethylene resin A polyethylene resin cross-linked foam obtained by crosslinking and foaming a resin composition containing ˜3 parts by mass by a chemical cross-linking foaming method.   The polyethylene-based resin crosslinked foam according to claim 1, wherein the antistatic agent is a surfactant-based antistatic agent.