JP2012092331A - Foamed plastic protective sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamed plastic protective sheet which has a high antistatic effect even when only a small amount of an antistatic agent has been added thereto, with which adhesion of stains to a board used for precision electronic equipment etc. due to bleed-out scarcely takes place, and further with which also a foreign substance adhered to the surface of the board is easily removed only by washing by water or by wiping with a cloth including water.SOLUTION: The foamed plastic protective sheet is a sheet-like member which is produced by extrusion molding of a thermoplastic plastic material, and is made to have closed cells at least inside thereof by adding a foaming agent to the plastic material, and for which a technical means is adopted, including addition of a polymeric antistatic agent and an ion liquid or a gemini-structured surfactant to the plastic material.

Description

  The present invention is an improvement of the protective sheet material, more specifically, it has a high antistatic effect even with a small addition amount, and there is almost no adhesion of dirt to a plate body used for precision electronic equipment by bleeding out. Further, the present invention relates to a foamed plastic protective sheet that can easily remove foreign substances adhering to the surface of the plate body by simply rinsing with water or a cloth containing water.

  As is well known, electronic precision equipment such as glass substrates used for flat-screen TV displays, etc. must be highly non-polluting on the surface. Each sheet material is sandwiched between a plurality of glass substrates for packaging and protection.

  Conventionally, as this sheet material, a protective sheet having a cell cushion structure formed by extruding a polyolefin-based thermoplastic material mixed with a foaming agent is used. This protective sheet is charged with static electricity. In order to prevent the adhesion of dust in the air that causes dirt by enhancing the antistatic performance, a polymer type antistatic agent is added (for example, see Patent Document 1).

  However, in such a conventional protective sheet, the bleed-out substance may bleed out on the surface of the protective sheet due to the additives and raw materials contained in the material. When packaged, the stain due to the bleed-out substance is transferred to the electronic precision device, and the surface of the electronic precision device may be soiled.

  Therefore, after removing packaging materials such as protective sheets, foreign matters such as attached dust and bleed-out substances are removed by washing the surface with water or wiping with water-containing sheets. Depending on the type and content of the additive contained in the sheet material, the burden of this removal operation is greatly affected.

JP 2007-262409 A

  The present invention has been made in view of the above-mentioned problems in the conventional protective sheet material, the purpose is to have a high antistatic effect even with a small addition amount, and In addition, there is almost no dirt on the plate used for precision electronic equipment by bleeding out, and foreign matter adhering to the surface of the plate can be easily removed by simply rinsing with water or a cloth containing water. An object of the present invention is to provide a foamed plastic protective sheet.

  Means employed by the present inventor for solving the above-described problems will be described with reference to the accompanying drawings.

  That is, the present invention is a sheet-like member formed by extruding a thermoplastic material, and a foaming agent is added to the plastic material so as to have at least closed cells inside the sheet. In the present invention, a foamed plastic protective sheet was completed by employing a technical means of adding a polymer type antistatic agent and an antistatic agent containing an ionic liquid.

  Furthermore, in order to solve the above-mentioned problems, the present invention employs a technical means in which the ionic liquid contains at least an alkyl ammonium and a sulfate ester in addition to the above means as necessary.

  The present invention also relates to a sheet-like member formed by extruding a thermoplastic material, wherein a foaming agent is added to the plastic material so as to have at least closed cells inside the sheet. In this case, a foamed plastic protective sheet was completed by employing a technical means of adding a polymer type antistatic agent and an antistatic agent containing a surfactant having a Gemini structure.

  In order to solve the above-mentioned problems, the present invention uses, as necessary, a polymer-type antistatic agent containing, as a main component, an ionomer resin containing an alkali metal or a hydrophilic resin. The technical means was adopted.

  Furthermore, in order to solve the above-mentioned problems, the present invention employs technical means that the number average molecular weight of the polymer antistatic agent is 2000 or more in addition to the above means as necessary.

  Furthermore, in order to solve the above-described problems, the present invention employs technical means of setting the thickness of the sheet body 1 to 0.2 to 2.0 mm in addition to the above means as necessary.

  Furthermore, in order to solve the above problems, the present invention adds 0.1 to 7.5 parts by weight of the antistatic agent to 100 parts by weight of the thermoplastic material in addition to the above means as necessary. The technical means of adding in proportion was adopted.

  In the present invention, a sheet-like member formed by extruding a thermoplastic material, and a foaming agent is added to the plastic material so as to have at least closed cells inside the sheet. By adding a polymer type antistatic agent and an ionic liquid or Gemini type surfactant to the plastic material, it has a high antistatic effect even with a small addition amount, and it can be applied to precision electronic equipment by bleed-out. There is almost no adhesion of dirt to the plate used, and foreign matter adhering to the surface of the plate can be easily removed by simply wiping with water or a cloth containing water, so the practical utility value is high It can be said that there is something expensive.

It is a perspective view showing the sheet material of embodiment of this invention. It is sectional drawing showing the use condition of the sheet | seat material of embodiment of this invention.

  The mode for carrying out the present invention will be described in more detail with reference to the drawings specifically illustrated as follows.

  An embodiment of the present invention will be described with reference to FIGS. 1 and 2. In FIG. 1, what is indicated by reference numeral 1 is a sheet body, and the sheet body 1 has at least closed cells 11, 11.

  The precision electronic device P of the present embodiment includes, for example, electronic products, precision devices, circuit boards, silicon semiconductors, glass substrates for displays, etc. As shown in FIG. The sheet body 1 can be sandwiched between the Ps.

  Thus, the foamed plastic protective sheet of the present embodiment is a sheet-like member formed by extrusion molding of a thermoplastic plastic material, and when configured, first, the plastic material (in this embodiment, polyethylene, A foaming agent is added to a polyolefin-based resin such as polypropylene to form at least closed cells 11, 11.

  In the present embodiment, as the blowing agent, for example, propane, normal butane, isobutane, normal pentane, isopentane, normal hexane, isohexane, and other aliphatic hydrocarbons, cyclopentane, cyclohexane, and other alicyclic hydrocarbons, methyl chloride, and chloride Chlorinated hydrocarbons such as ethyl, fluorinated hydrocarbons such as 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, ethers such as dimethyl ether, diethyl ether and ethyl ether, others, dimethyl carbonate, methanol, Examples include organic physical foaming agents such as ethanol, and inorganic foaming agents such as oxygen, nitrogen, carbon dioxide, air, and water. These foaming agents can be used alone or in admixture of two or more.

  Among these, an organic physical foaming agent is preferable from the viewpoint of compatibility with a polyolefin resin and foaming properties, and among them, a material mainly containing normal butane, isobutane, or a mixture thereof is preferable. Although not a physical foaming agent, a decomposable foaming agent such as azodicarbonamide can also be used.

  Moreover, the addition amount of the said foaming agent is adjusted according to the kind of foaming agent, and the density of the target protective sheet. In this embodiment, a physical foaming agent such as isobutane can be employed as the foaming agent, and the blending ratio is 4 to 35 parts by weight, preferably 5 to 30 parts by weight, more preferably 6 parts per 100 parts by weight of the plastic material. ~ 25 parts by weight.

  Further, when producing a protective sheet, a bubble regulator is usually added to the plastic material (polyolefin resin) supplied to the extrusion molding machine. Ethylene or the like) or an inorganic system can be employed.

  Moreover, as needed, various additives generally used, such as a coloring agent, an ultraviolet-ray inhibitor, and antioxidant, can also be mix | blended with the manufacture of a protection sheet suitably.

  First, a polymer type antistatic agent is added to the plastic material. As the polymer type antistatic agent of this embodiment, for example, an ionomer resin containing an alkali metal such as potassium, rubidium or cesium, or a resin mainly composed of a hydrophilic resin such as polyetheresteramide or polyether is adopted. can do.

  In this case, the polymer type antistatic agent can improve the compatibility with the polyolefin resin that is a material of the sheet-like member to obtain an excellent antistatic effect, and the physical properties by adding the antistatic agent In order to acquire the effect which suppresses the fall of this, it is preferable to use the resin which carried out block copolymerization of polyolefin resin.

  The number average molecular weight (Mn) of the polymer type antistatic agent of this embodiment is 2000 or more, more preferably 2000 to 100,000, and is distinguished from an antistatic agent comprising a surfactant. The The upper limit of the number average molecular weight of the polymeric antistatic agent is about 500,000.

In addition, the melting point of the polymer antistatic agent in the present embodiment is 70 to 270 ° C., more preferably 80 to 200 ° C., and the surface resistance value is less than 1.0 × 10 ¹² (Ω). Consists of.

  The polymer antistatic agent in this embodiment can be used individually or in multiple. As specific examples of products, “Pelestat 300” manufactured by Sanyo Chemical Industries, Ltd. (polyether-polypropylene block copolymer: melting point 136 ° C., number average molecular weight 14000, density 990 g / L), manufactured by Mitsui DuPont Polychemical Co., Ltd. SD100 "or the like can be employed.

  Moreover, in this embodiment, an ionic liquid can be employ | adopted as an antistatic agent to add further, and what contains at least alkylammonium and a sulfuric ester can be employ | adopted as this ionic liquid.

Specific physical properties of this ionic liquid are: heat loss: stable up to 270 ° C., viscosity: 1400 mPa · s (20 ° C.), density: 1.07 g / cm ⁻³ (20 ° C.), soluble in water It is.

  As for ionic liquids, ordinary salts are solid at room temperature like salt, but by replacing the ions that make up the salts with certain organic ions of relatively large size, the melting point is lowered and near room temperature ( 25 ° C.) that exists in a liquid state.

  In addition, an ionic liquid is classified roughly into three types, a pyridine type, an alicyclic amine type, and an aliphatic amine type, with the kind of cation. Various structures can be synthesized by selecting the type of anion to be combined therewith. Cations used include ammonium, phosphonium and non-ionic ions such as imidazolium and pyridinium salts, while anions include halogens such as bromide and triflate, and boron such as tetraphenylborate. And phosphorus systems such as hexafluorophosphate.

  In the present embodiment, a gemini type surfactant (dimer surfactant) may be employed as the antistatic agent added to the plastic material. The gemini structure is a structure composed of a single chain and one hydrophilic group, in which two surfactant molecules are linked by a covalent bond via a spacer.

  In general, gemini-type structural surfactants include at least two hydrophobic chains, at least two ionic or polar groups, and a spacer. Gemini structures are either symmetric (same tail, same head) or asymmetric.

  The polar group includes a polyether and a sugar. Examples of ionic groups include cations and anions. Specific examples of ionic groups also include ammonium, phosphate, sulfate, and carboxylate ions.

  The spacer includes a polar or nonpolar group. Specific examples of spacer groups include amide groups, short or long methylene groups, stilbene groups, polyether groups, aliphatic groups, and aromatic groups.

  This surfactant with Gemini structure has much better micelle formation performance and surface activity than ordinary ionic surfactants, and it is environmentally friendly because its functions can be achieved with a small amount of addition. It has a feature that it has a high carbon number but a low crafting point.

  And in this embodiment, it is suitable to add an antistatic agent in the ratio of 0.1-7.5 (more preferably 5.0) weight part with respect to 100 weight part of a thermoplastic material. . As the antistatic agent, as described above, an ionic liquid and a Gemini-type surfactant can be used alone or in combination.

  Then, low density polyethylene (LDPE) and the above-mentioned antistatic agent are supplied to the extrusion molding machine, volatile gas (butane) is injected from the middle of the cylinder, melt-kneaded, and the circular die attached to the tip of the mouth Thus, the pressure is released to normal pressure and stretched to a predetermined circumference by an annular cooling device.

  Thereafter, this was cut along the extrusion direction to produce a sheet having a thickness of 0.4 mm. In the present embodiment, the thickness of the sheet body 1 can be 0.2 to 2.0 mm.

  In this way, the protective sheet of the present invention can be completed. As shown in FIG. 2, the sheet body 1 can be sandwiched between the precision instrument plates P and P and used. And after removing a protection sheet, the foreign material adhering to the surface of a board can also be easily removed only by wiping with a cloth containing water washing or water.

  The results of the physical property test of the foamed plastic protective sheet of the present embodiment are shown in Table 1 below.

  In this test, the foamed plastic protective sheet of the present embodiment is attached to a glass substrate, and immediately after peeling the sheet is referred to as “before cleaning”, and after the peeling, the surface of the glass substrate is lightly washed with “washing”. "After".

  In Examples 1 to 3 and Comparative Examples 1 and 2, the number of particles is the number of particles (particles) of 2.6 μm or more existing in a square area of 2.0 × 2.5 mm, and image processing software is used. On the other hand, in Comparative Examples 3 and 4, the number of particles (particles) having a size of 10 μm or more existing in a square area of 2.0 × 2.5 mm was visually counted.

In this test, the standard value satisfying the quality of dirt adhesion is less than 100 if the contact angle after cleaning is less than 5.0 degrees and the number of particles after cleaning is 2.6 μm or more, 10 μm or more. If it is less than 25, the surface resistivity is less than 1.0 × 10 ¹² .

  From the test results, in Examples 1 to 3 of the present invention, a product satisfying the standard value of the quality of dirt adhesion was obtained, but in Comparative Examples 1 to 4, numerical items not satisfying the necessary standard (The symbol ▲ in the table is a non-standard value).

  The present invention is generally configured as described above. However, the present invention is not limited to the illustrated embodiment, and various modifications are possible within the description of the “claims”. The surfactant to be added together with the mold antistatic agent may be any surfactant as long as it has a Gemini structure, and the blending ratio can be changed according to the application.

  In addition, the ionic liquid is not limited to those containing alkylammonium and sulfate, and other ionic liquids can be employed, and any of these is within the technical scope of the present invention.

1 Seat body
11 Bubble P Precision machine plate

Claims (7)

A sheet-like member formed by extruding a thermoplastic material,
While the plastic material is added with a foaming agent and has at least closed cells inside the sheet,
A foamed plastic protective sheet, wherein a polymeric antistatic agent and an antistatic agent containing an ionic liquid are added to the plastic material.   2. The foamed plastic protective sheet according to claim 1, wherein the ionic liquid contains at least alkyl ammonium and sulfate. A sheet-like member formed by extruding a thermoplastic material,
While the plastic material is added with a foaming agent and has at least closed cells inside the sheet,
A foamed plastic protective sheet, wherein a polymer type antistatic agent and an antistatic agent containing a Gemini type surfactant are added to the plastic material.   The foamed plastic protective sheet according to any one of claims 1 to 3, wherein the polymer type antistatic agent contains an ionomer resin containing an alkali metal or a hydrophilic resin as a main component.   The foamed plastic protective sheet according to any one of claims 1 to 4, wherein the polymer type antistatic agent has a number average molecular weight of 2000 or more.   The foamed plastic protective sheet according to any one of claims 1 to 5, wherein the sheet body (1) has a thickness of 0.2 to 2.0 mm.   The antistatic agent is added in a proportion of 0.1 to 7.5 parts by weight with respect to 100 parts by weight of the thermoplastic material, according to any one of claims 1 to 6. Foamed plastic protective sheet.

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