JP2001328395A - Desk mat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desk mat of a polyolefin resin which shows high resistance to scratch and contamination. SOLUTION: This desk mat has an acrylic soft resin layer formed at least on one face of a polyolefin resin sheet, on the surface of which, a curable resin layer is formed, while the acrylic soft resin layer is formed on the back. The acrylic soft resin layer is preferably of such a kind that the content of aliphatic amide is 0.1-3.0 wt.% and/or the content of metallic soap is the same as shown to the acrylic soft resin. In addition, it is preferable to blend 0.1-2.0 wt.% antioxidant to the acrylic soft resin together with the aliphatic amide and/or the metallic soap. Further, the polyolefin resin is preferably an ethylene-α-olefin copolymer containing 10-40 wt.% 4-8C α-olefin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a desk mat using a polyolefin resin and an acrylic soft resin as materials.

[0002]

2. Description of the Related Art Desk mats are conventionally made of a resin composition in which a plasticizer, a stabilizer and the like are blended with a polyvinyl chloride resin. The mat made of polyvinyl chloride resin has excellent properties such as transparency, flexibility and good heat stability, but the plasticizer bleeds out to the mat surface during use, for example, in a desk mat, There is a disadvantage that undesired phenomena such as the printing ink of the copy paper sandwiched between the desk and the desk mat adhering to the surface of the desk mat are caused. In recent years, desk mats made of resins other than polyvinyl chloride resins have been studied, and polyolefin resins such as ethylene-alkyl (meth) acrylate and ethylene-octene copolymers, and acrylic resins have been studied. Desk mats using a soft resin as a material have been proposed.

[0003] A desk mat using a polyolefin resin as a material has a drawback that the surface strength is weak and the stain resistance is not good, so that measures must be taken to provide an ultraviolet-curable resin layer on both surfaces thereof, resulting in an increase in cost. is there. Further, the acrylic soft resin is excellent in stain resistance, but has poor elastic recovery property, and has a problem that the recovery property of a written mark is inferior. SUMMARY OF THE INVENTION An object of the present invention is to provide a low-cost desk mat that has good transparency and flexibility, has excellent stain resistance, and has good handwriting recovery.

[0004]

According to the present invention, there is provided a desk mat comprising a polyolefin resin sheet provided with an acrylic soft resin layer on at least one surface. Further, the present invention is a desk mat in which a curable resin layer is provided on a front surface of a polyolefin resin sheet and an acrylic soft resin layer is provided on a back surface. The acrylic soft resin layer preferably contains 0.1 to 3.0% by weight of fatty acid amide and / or metal soap based on the acrylic soft resin. Further, it is preferable to add 0.1 to 2.0% by weight of an antioxidant to the acrylic soft resin together with the fatty acid amide and / or the metal soap. As the polyolefin-based resin, an ethylene-α-olefin copolymer having an α-olefin content of 4 to 8 carbon atoms and a content of 10 to 40% by weight is preferable.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyolefin resin used in the present invention is polyethylene such as low-density polyethylene and high-density polyethylene; ethylene-α-olefin copolymer; ethylene-vinyl acetate copolymer; ethylene-vinyl alcohol copolymer. Copolymer; ethylene ionomer; ethylene-alkyl (meth) acrylate copolymer such as ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer Copolymer; Ethylene-alkyl (meth) acrylate-maleic anhydride copolymer; Ethylene- (meth) acrylic acid copolymer; Ethylene copolymer such as ethylene-styrene copolymer; random polypropylene, isotactic polypropylene, atactic Click polypropylene, polypropylene such as syndiotactic polypropylene; polypropylene and styrene-butadiene copolymer, a mixture of hydrogenated products thereof.

[0006] Among them, ethylene copolymers can be suitably used because they have good transparency and flexibility. Among them, ethylene-α-olefin copolymers are preferable, and α-olefin copolymers having 4 to 8 carbon atoms are particularly preferable in terms of transparency and flexibility. α-olefin copolymerization ratio is 1
When the amount of the copolymer component is 0 to 40% by weight and the amount of the copolymer component is 10% by weight or less, a writing mark may be left when writing pressure is high when writing with a ballpoint pen, and transparency and flexibility are poor. On the other hand, if the content of the copolymer component is 40% by weight or more, the paper may be broken when writing with a ballpoint pen at a high writing pressure due to excessive elasticity. In addition, heat resistance is poor, and when a hot object such as a cup of teacup is placed on the desk mat, traces of the bowl may remain on the desk mat. More preferably, the copolymerization ratio of the α-olefin is 15 to 20% by weight, and the one having this range has transparency and flexibility, furthermore has good heat resistance, and a hot thing such as a teacup is placed on a desk mat. This is particularly preferable because no trace of the bowl is left on the desk mat. As the α-olefin having 4 to 8 carbon atoms of the copolymer component, 1-butene, 1-pentene,
Examples include 1-hexene, 1-heptene, and 1-octene such as 4-methyl-1-pentene. In particular, an ethylene-1-butene copolymer containing 1-butene as a copolymer component is very preferable because of its good balance in terms of transparency and flexibility as a desk mat.

As the polyolefin resin, an ethylene-1-octene copolymer and an ethylene-1-hexene copolymer polymerized by using a metallocene catalyst are also preferably used. An ethylene-1-octene copolymer having a 1-octene content of 15 to 40% by weight is preferred in view of the recovery of writing traces. The polyolefin-based resin is preferably a resin exhibiting flexibility at room temperature, such as soft polyvinyl chloride, and two or more kinds may be used in combination. In addition, the uppermost layer is composed of the above-mentioned ethylene-α-olefin copolymer in consideration of writing properties, and the lower layer is composed of random polypropylene, syndiotactic polypropylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol. A multilayer polyolefin resin sheet provided with a copolymer, an ethylene ionomer, an ethylene-alkyl (meth) acrylate copolymer, and an ethylene-alkyl (meth) acrylate-maleic anhydride copolymer may be used. Further, a plasticizer, an ultraviolet absorber, an antistatic agent, a pigment, an antiblocking agent, an antibacterial agent, an antifungal agent and the like may be added to these polyolefin resins as required.

The acrylic soft resin used in the present invention is a resin which exhibits flexibility at room temperature, such as soft polyvinyl chloride. The acrylic soft resin is preferably a polymer having a multilayer structure, that is, a polymer in which two or more acrylic polymers form a core-shell type multilayer structure. These acrylic soft resins exhibit good flexibility at room temperature, have bending durability, and are excellent in transparency and weather resistance.

An example of an acrylic soft resin will be described. 30 to 99.9% by weight of at least one alkyl acrylate having an alkyl group having 1 to 12 carbon atoms,
0 to 70% by weight of at least one alkyl methacrylate having an alkyl group of 8 to 0 to 30% by weight of a copolymerizable unsaturated monomer, polyfunctional crosslinking monomer and / or polyfunctional graft monomer 10 to 90 parts by weight of at least one polymer layer [A] having a Tg of 30 ° C. or lower obtained by polymerizing a monomer mixture consisting of 0.1 to 10% by weight of a polymer and an alkyl having 1 to 12 carbon atoms 30 to 99% by weight of at least one alkyl acrylate having an alkyl group, 1 to 70% by weight of at least one alkyl methacrylate having an alkyl group having 1 to 8 carbon atoms, and a copolymerizable unsaturated monomer 0 to T obtained by polymerizing a monomer mixture consisting of 30% by weight
Acrylic resin having a multilayer structure composed of a combination of 90 to 10 parts by weight of at least one polymer layer [B] having a g of −20 to 50 ° C. and an outermost layer being the polymer layer [B]. It is a soft multilayer structure resin.

Another example of the acrylic soft resin will be described. 60 to 99.5% by weight of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, 0 to 39.5% by weight of a monofunctional monomer having one copolymerizable vinyl group, and a vinyl group or vinylidene Rubber layer 30 to 8 obtained by polymerizing 0.5 to 5% by weight of a polyfunctional monomer having at least two groups
0% by weight, 40 to 100% by weight of methyl methacrylate, 0 to 60% by weight of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, and a monomer having a copolymerizable vinyl group or vinylidene group And a hard resin layer obtained by polymerizing 0 to 20% by weight of a hard resin layer.

Further, another example of the acrylic soft resin will be described. (A) 80 to 98.9% by weight of methyl methacrylate, 1 to 20% by weight of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, polyfunctional grafting agent 0.0
5 to 30 parts by weight of an innermost hard polymer layer obtained by polymerizing a monomer mixture comprising 1 to 1% by weight and 0 to 0.5% by weight of a polyfunctional crosslinking agent; (B) 1 to 8 carbon atoms 70 to 99.5% by weight of an acrylic acid alkyl ester having an alkyl group of
0 to 30% by weight of methyl methacrylate, 0.5 to 5% by weight of a polyfunctional grafting agent and 0 to 5% by weight of a polyfunctional crosslinking agent
(C) methyl methacrylate 9: 20 to 45 parts by weight of a hard polymer layer as an intermediate layer obtained by polymerizing a monomer mixture comprising
An outermost hard polymer layer 50 to 7 formed by polymerizing a monomer mixture comprising 0 to 99% by weight and 10 to 1% by weight of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms.
It is an acrylic soft multilayer structure resin having 5 parts by weight and an average particle size of 0.01 to 0.3 μm.

The above-mentioned polyolefin resin and acrylic soft resin are formed into a sheet by calendering, extrusion or the like. Then, an acrylic soft resin sheet is overlaid on one or both sides of the polyolefin resin sheet, and is laminated by pressing and heating using a laminating machine. In addition, this polyolefin resin sheet,
Thin sheets of the same polyolefin resin or thin sheets of different polyolefin resins may be laminated. Similarly, the acrylic soft resin sheet may be composed of multiple layers. Further, a desk mat may be formed by co-extrusion molding a polyolefin resin and an acrylic soft resin. In the present invention, the ratio of the polyolefin resin layer to the acrylic soft resin layer in the thickness direction of the desk mat is not particularly limited and is arbitrary, but is preferably 95: 5 to 5:95. The sheet surface may be subjected to squeezing if necessary. Cut into the appropriate shape and size to make a desk mat shape. The thickness of the desk mat is usually 0.5 to 3 mm.

When laminating an acrylic soft resin sheet on one or both sides of a polyolefin resin sheet, it is preferable to provide a primer layer on the lamination surface of the polyolefin resin sheet to improve the adhesiveness. Examples of the adhesion primer layer include a polyurethane primer layer and an epoxy resin primer layer. By forming the primer layer, a polyolefin resin sheet and an acrylic soft resin sheet can be firmly and durably laminated. In order to provide the above-mentioned adhesive primer layer on the surface of the polyolefin-based resin sheet, it is preferable that the sheet is previously subjected to a corona discharge treatment, and then an adhesive primer is applied to form a primer layer. By performing the corona discharge treatment, the bonding property of the adhesive primer to the sheet can be increased.

As the polyurethane of the polyurethane primer layer, a polyester polyurethane is preferable. That is, a condensed polyester polyol obtained by a condensation reaction of a dibasic acid such as adipic acid or phthalic acid with a glycol such as ethylene glycol or 1,4-butanediol or a triol such as trimethylolpropane, tolylene diisocyanate, or diphenylmethane Polyurethane using a curing agent such as diisocyanate or tolidine diisocyanate as a raw material is preferable.

Examples of the epoxy resin for the epoxy resin primer layer include bisphenol A type, hydrogenated or bromide thereof, glycidyl ether type epoxy resin such as bisphenol F type and biphenyl type, and phenol novolak type epoxy resin. Glycidyl ester type epoxy resins, glycidylamine type epoxy resins such as tetraglycidyldiaminidiphenylmethane and the like are used. Examples of the curing agent include amines such as diethylenetriamine, triethylenetetramine, isophoronediamine, and diaminodiphenylmethane; amine-modified products such as polyamide obtained by modifying these amines with dimer acid; acid anhydrides such as dodecenylsuccinic anhydride and hexahydrophthalic anhydride. And diisocyanates such as tolylene diisocyanate, isocyanate prepolymer and blocked isocyanate.

The primer obtained by mixing the above epoxy resin with the reaction product of hexamethylene glycol, adipic acid and phthalic acid, and using tolylene diisocyanate as a curing agent has heat resistance and cold resistance. Are also preferred because they are also excellent. In the reaction product of hexamethylene glycol, adipic acid and phthalic acid, the weight ratio of adipic acid to phthalic acid is preferably 1: 1. The reactant may be in the form of a mixture of polyhexamethylene adipate and polyhexamethylene phthalate, or in the form of a co-condensation of hexamethylene adipate and hexamethylene phthalate.

Although the surface of the desk mat is easily damaged for the purpose, the polyolefin resin sheet and the acrylic soft resin sheet have poor surface scratch resistance. for that reason,
In the desk mat of the present invention, it is preferable to provide a curable resin layer on the surface of the desk mat. The curable resin is applied in the form of a solvent solution or an aqueous dispersion, and is cured to form a curable resin layer. As the curable resin, a polyurethane resin, an epoxy resin composed of bisphenol A type epoxy or the like and an aliphatic or aromatic amine epoxy is preferably used. These curable resins may be one-pack or two-pack. Ultraviolet curable resins are particularly preferably used. As UV-curable resin,
Radical polymerizable resins having an acryloyl group such as urethane acrylate, epoxy acrylate and melamine acrylate are preferably used.

By blending a resin such as a nylon resin, an acrylic resin, a urethane resin, or a benzoguanamine resin or fine particles of silica having a particle diameter of 5 to 40 μm with the curable resin layer, the light reflectivity of the mat surface is adjusted. The reflection can be softened. In addition, when applying the anti-scratch layer containing these fine particles to the mat surface, a part of the fine particles are projected to the surface of the curable resin layer, thereby improving the cracking and scratching of the surface when bending the mat. May be. Even if the formation of this curable resin layer is performed at the above-mentioned sheet-like stage,
It may be performed after cutting into a mat shape.

Although the acrylic soft resin itself is excellent in the stain resistance for a time, the melting point of the toner tends to be lowered with the speeding up of the copying machine in recent years. When the copy paper is sandwiched, the desk mat may be stained with the print ink of the copy paper. Such dirt is removed by adding an aliphatic amide and / or
Alternatively, it can be prevented by adding a metal soap. As the aliphatic amide, methylenebisstearylamide, ethylenebisstearylamide, ethylenebisoleylamide, stearylamide, oleylamide and the like are used. As the metal soap, zinc stearate, zinc oleate, lithium stearate, calcium stearate and the like are used. Aliphatic amide and / or
Alternatively, the amount of the metal soap is 0.1% based on the acrylic soft resin.
It is 1 to 3.0% by weight, preferably 0.5 to 2.0% by weight.

However, when an aliphatic amide and / or a metallic soap is blended with an acrylic soft resin, the blended aliphatic amide or metallic soap yellows due to oxidation at the time of molding, although the advantages described above are obtained. The acrylic soft resin sheet may be discolored and its transparency may be reduced. In order to prevent this decrease in transparency, it is preferable to use an aliphatic amide and / or a metal soap in combination with an antioxidant. Antioxidants are classified into radical scavengers and peroxide decomposers when classified according to their functions. In the present invention, both of them are preferably used in combination.

As the above radical scavenger, pentaerythrityl-tetrakis [3- (3,5-t-butyl-4)
-Hydroxyphenyl) propionate], 2,6-di-butyl-4-methylphenol, n-octadecyl-
3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, tetrakis- [methylene-3-
(3 ', 5'-di-t-butyl-4-hydroxyphenyl) propionate] phenolic antioxidants such as methane and 2,2-methylenebis (4-methyl-6-t-butylphenol). Examples of the peroxide decomposer include thioether antioxidants such as dilauryl-3,3'-thiodipropionate and distearyl-3,3'-thiodipropionate, trisnonylphenylphosphite, distearyl. Examples thereof include phosphorus-based antioxidants such as pentaerythritol diphosphite and tris (2,4-di-t-butylphenyl) phosphite. The content of the antioxidant is 0.1 to 2.0% by weight, preferably 0.3 to 1.0% by weight, based on the acrylic soft resin. The acrylic soft resin may contain a plasticizer, an ultraviolet absorber, an antistatic agent, a pigment, an antiblocking agent, an antibacterial agent, a fungicide, and the like, if necessary.

Preferred examples of the embodiment of the desk mat of the present invention include a curable resin layer on the front surface (upper surface) and an acrylic soft resin layer on the back surface (lower surface) of the polyolefin resin sheet, and in particular, a polyolefin resin resin having a thickness of 0.1%. A desk mat provided with an acrylic soft resin layer containing 1 to 3.0% by weight of a fatty acid amide and / or metal soap and 0.1 to 2.0% by weight of an antioxidant. The polyolefin-based resin sheet has good handwriting recovery properties, and its surface is covered with a curable resin, so that it has good scratch resistance. The back,
In other words, the surface in contact with the desk is made of an acrylic soft resin layer, so that it is excellent in stain resistance. Particularly, those containing fatty acid amide and / or metal soap are contaminated even when a copy paper copied with ink using a low melting point toner is sandwiched. Can prevent.

Further, the acrylic soft resin sheet is calendered and wound into a roll, and when the sheet is unwound from this roll, depending on the type and composition of the acrylic soft resin, blocking occurs and the sheets are separated from each other. Can be difficult. By blending a small amount of fatty acid amide and / or metal soap, especially fatty acid amide, the above-mentioned blocking can be eliminated without using an interleaf paper. For this purpose, the amount of the fatty acid amide and / or the metal soap is 0.1% based on the acrylic soft resin.
It is preferably from 0.5 to 0.4% by weight. If the content is less than 0.05% by weight, peeling cannot be easily performed, and if it is more than 0.4% by weight, transparency is adversely affected. In this case, it is preferable to use an antioxidant as described above in combination.

[0024]

The present invention will be described in more detail with reference to Examples and Comparative Examples. Examples 1-3, Comparative Examples 1-2 Ethylene-1-octene copolymer (EG8150: 1-octene content 25% by weight) manufactured by Dow Chemical Company, ethylene-1-butene copolymer manufactured by Sumitomo Chemical Co., Ltd. (Esprene SPO N-0394: 1-butene content 17% by weight), an acrylic soft resin (SA-
1000-FO and GR), metal soap (zinc stearate), fatty acid amide (methylenebisstearylamide), phenolic antioxidant (n-octadecyl-3)
Using-(3,5-di-t-butyl-4-hydroxyphenyl) propionate) and a phosphorus-based antioxidant (distearylpentaerythritol diphosphite), compounding and preparing the resin compositions A to D shown in Table 1. did.

[0025]

[Table 1]

The ethylene-1-octene copolymer A was extruded from a T-die using an extruder, and had a thickness of 1.3 mm and a thickness of 1.3 mm.
A 5 mm sheet was formed. Further, the ethylene-1-butene copolymer B was extruded from a T-die with an extruder, and formed into a sheet having a thickness of 1.3 mm. The acrylic soft resin compositions C and D were calendered to a thickness of 0.2 m.
m. The ethylene-1-octene copolymer sheet obtained by the above-described calendering and the acrylic soft resin sheet were stacked so as to have a layer structure shown in Table 2, and heat-laminated with a laminating machine (Examples 1 to 3; Example 2). In laminating, a corona discharge treatment was applied to each laminated surface of the ethylene-1-octene copolymer sheet and the ethylene-1-butene copolymer sheet to provide a polyurethane-based primer layer. In addition, thickness 1.5m
m-ethylene-1-octene copolymer sheet was used alone without lamination (Comparative Example 1).

Next, a urethane acrylate-based ultraviolet curable resin coating material was applied to one surface of each of the above-mentioned sheets other than Comparative Example 2 (in the case of a laminated sheet, the surface of the ethylene-1-octene copolymer sheet layer). Then, the coating material was cured by irradiating ultraviolet rays to form an ultraviolet-curable resin layer having a thickness of 20 μm. Each obtained sheet was cut to obtain a desk mat. For each of the obtained desk mats, the presence or absence of bloom during storage at room temperature and the presence or absence of discoloration (transparency) of each of the obtained films were examined. Further, each surface was subjected to 100 g under a 500 g load using a Gakushin abrasion tester using a No. 3 gold wire.
The surface was rubbed repeatedly, and the surface condition at this time was visually observed to examine the scratchability of the upper and lower surfaces. In addition, place a bowl containing boiling water on each of the desk mats (the temperature of the bowl contact portion of each desk mat exceeds 70 ° C.). When the boiling water has dropped to room temperature, remove the bowl. The trace of the bowl was visually observed. Further, a copy paper was placed on the opposite side of the surface of the desk mat on which the ultraviolet-curable resin layer was formed, and left standing at a load of 100 g / cm ² at 60 ° C. for 24 hours, and the surface of each desk mat was visually inspected for contamination. Was. Table 2 also shows the results. In Table 2, ○ indicates no bloom. ◎ in the item of discoloration indicates no discoloration. In the item of scratchability, ○ indicates no scratch, and X indicates scratch. In the section on the trace of teacup bowls, ○ indicates no trace, and Δ indicates slightly traced.
In the section of the copy paper contamination, ○ indicates no contamination and × indicates contamination.

[0028]

[Table 2]

[0029]

The polyolefin resin sheet has poor stain resistance, is poor in surface strength, and is easily damaged. Therefore, in the case of a polyolefin resin desk mat, measures have conventionally been taken to provide ultraviolet curable resin layers on both surfaces thereof. And the cost was high. In the present invention, an acrylic soft resin layer is provided on at least one side instead of the ultraviolet curable resin layer, so that cost can be reduced. Further, since the acrylic soft resin has good stain resistance, by using the acrylic soft resin layer on the lower surface of the polyolefin resin desk mat, it is possible to prevent the copy paper from being stained by the printing ink by the copying machine. Also, by using an acrylic soft resin blended with fatty acid amide and / or metal soap,
This effect can be further enhanced. When the fatty acid amide and / or the metal soap is blended with an antioxidant, the decrease in transparency (yellowing) due to the blending of the fatty acid amide and / or the metal soap can be prevented.

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Claims (5)

[Claims] 1. A desk mat having an acrylic soft resin layer provided on at least one surface of a polyolefin resin sheet. 2. A desk mat comprising a polyolefin resin sheet provided with a curable resin layer on the front surface and an acrylic soft resin layer on the back surface. 3. The acrylic soft resin layer contains 0.1 to 3.0% by weight of fatty acid amide and / or acrylic soft resin based on the acrylic soft resin.
3. The desk mat according to claim 1, further comprising a metal soap. 4. A fatty acid amide and / or a metal soap,
4. The desk mat according to claim 1, further comprising 0.1 to 2.0% by weight of an antioxidant based on the acrylic soft resin. 5. A polyolefin resin comprising an ethylene-α having an α-olefin content of 4 to 8 carbon atoms of 10 to 40% by weight.
The desk mat according to claim 1, which is an olefin copolymer.