JPH0441648B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a foam decorative sheet made of vinyl chloride resin (hereinafter referred to as PVC) useful as a covering material such as a wall covering material with excellent design and durability, and a method for producing the same. Decorative sheets, which are made by forming a PVC-based resin layer on a base material such as paper or cloth and giving it variations in color, shape, and gloss, are widely used as wall coverings and flooring materials. ing. In particular, the use of foamed resin layers is increasing due to their excellent design depth, flexibility, and strength of the base material. So far known methods for producing decorative foam sheets include the so-called mechanical embossing method, in which the sheet is embossed with heat and pressure before or after foaming to mechanically create irregularities; foamable ink or Applying the sol partially onto the base material or onto a foamed or non-foamed resin layer formed on the base material using a rotary screen, an intaglio, etc.,
Foam printing method, which heats and foams this to obtain a molded product;
A chemical embossing method in which a molded product is obtained by printing an ink layer containing an agent or crosslinking agent that suppresses or promotes foaming on a foamable resin layer containing a foaming agent, and then foaming the layer; heat-melting between the upper and lower layers. There are wrinkled foaming methods that form irregular wrinkled foams depending on the difference in texture, and a wide variety of decorative sheets are manufactured and put into practical use by these methods. In order to improve the design, weight, and evenness of decorative foam sheets obtained by these methods without increasing the weight of the sheet, it is effective to increase the foaming ratio. Are known. However, when the foaming ratio is increased, the strength of the foamed parts decreases significantly, especially the mechanical strength of the surface of the convex parts. A method has been used to maintain strength by forming a protective layer. Additionally, decorative sheets are generally used for relatively long periods of time, such as wall coverings and furniture, and measures should be taken to prevent discoloration and staining during this period. A PVC-based surface treatment agent or non-foamed vinyl plastisol has been coated over the entire surface of the sheet and applied in the previous methods described above. However, the effects and sustainability of these methods are insufficient, and they not only limit the design but also lead to an increase in the number of steps. Therefore, as a result of repeated studies to obtain a foam sheet with excellent design and strength, the present inventors added fine powder of methacrylate resin on a foamable soft PVC layer to prevent the resin from dissolving or swelling.
When a plastisol uniformly dispersed in a plasticizer for PVC is applied to the area where a convex portion is to be formed, the plasticizer in the plastisol migrates to the foamable PVC layer of the area where the plastisol is applied. Because the melt viscosity of the expandable PVC in this part is lower than in other parts, heating will cause this part to melt more quickly.
In order to reach a higher expansion ratio, a convex portion can be formed, and a strong molten film is formed on the surface of the convex portion, where the plasticizer is removed from the resin in the plastisol. The surface has no holes or irregularities, and is resistant to dirt.
It was discovered that the sheet can withstand friction from hands, cloth, etc., and exhibits excellent design and durability as a decorative sheet, leading to the completion of the present invention. That is, the present invention provides (1) a base material A, a soft vinyl chloride resin foam layer B formed thereon, and a polymethacrylate component that covers all or part of the convex portions of this foam layer in an amount of 70% by weight or more; Average molecular weight is 40000
and (2) a foamable soft vinyl chloride resin layer on a base material. After forming, on this layer, a methacrylate resin containing a polymethacrylate component of 70% by weight or more, a weight average molecular weight of 40,000 or more, and an average particle diameter of 50μ or less is added to a vinyl chloride resin that does not dissolve or swell this resin. This invention provides a method for producing a foam sheet, which comprises partially applying plastisol dispersed in a plasticizer and then heating the foam sheet to produce a foam sheet in which the plastisol-applied areas become convex portions. be. The methacrylate resin used in the present invention is a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate containing 70% by weight or more of polymethyl methacrylate and an unsaturated compound copolymerizable with the methyl methacrylate. hand,
Those having a composition that is compatible with PVC are used alone or in combination with other resins. Examples of unsaturated compounds copolymerizable with methyl methacrylate include unsaturated carboxylic acids and their esters such as acrylic acid and methacrylic acid; unsaturated nitriles such as acrylonitrile, methacrylonitrile, and chloroacrylonitrile; acrylamide, N
- Unsaturated amides such as methylol acrylamide, 2-acrylamido-2-methylpropanesulfonic acid; aromatic vinyl compounds such as styrene, P-methylstyrene, chlorostyrene, α-methylstyrene; phthalic acid, maleic acid, itaconic acid, Polyhydric carboxylic acid derivatives such as these anhydrides, alkyl esters, alkanol esters, alkylamides, N-substituted imides, such as maleic anhydride,
Examples include diethyl maleate, monomethyl maleate, di-2-hydroxyethyl maleate, monomethyl itaconate, methyl itaconate, N-methylmaleimide, N-P-hydroxyquenylmaleimide, and the like. These methacrylate resins usually have a weight average molecular weight of 40,000 or more and have an average particle diameter of 50 μm or less, preferably 10 μm or less in plastisol dispersed in a PVC plasticizer. molecular weight
If it is less than 40,000, the plasticizer will migrate to the foam layer and the strength of the layer after melting and forming will not be sufficient. Also useful are methacrylate resins containing a gel component that is insoluble in tetrahydrofuran, but in this case, the amount of gel component should be suppressed to 50% by weight or less. Should be used as a dispersion medium for methacrylate resins
As a plasticizer for PVC, it is liquid at room temperature,
In particular, one is selected that does not dissolve or swell the methacrylate resin to be dispersed.
Examples thereof are described in "Practical Handbook of Additives for Plastics and Rubber" published by Kagaku Kogyosha on August 10, 1971, pages 52 to 55. The type of plasticizer should be selected for elongation, especially depending on the composition of the methacrylate resin used. For example, when using a methyl methacrylate homopolymer, a plasticizer with strong dissolving power such as dibutyl phthalate or butylbenzyl phthalate is unsuitable because it causes the methacrylate resin to swell. Such as long chain alkyl esters of phthalic acids such as di-2-ethylhexyl phthalate and butyl lauryl phthalate, and alkyl esters of aliphatic dibasic acids such as dioctyl adipate and dioctyl sebatate.
Plasticizers with an SP value of 9.1 or less are suitable in this case. On the other hand, when using a methacrylate copolymer containing acrylonitrile as a copolymerization component, it may be possible to use a plasticizer with stronger dissolving power. The amount of plasticizer used may be within a range that allows the methacrylate resin to become plastisol.
Although not particularly limited, it is generally 40 to 1000 parts by weight per 100 parts by weight of resin. The methacrylate resin plastisol used in the present invention contains a compound that can cause crosslinking when heated, thereby crosslinking the methacrylate resin layer on the surface of the convex portion, improving heat resistance and durability. It is also possible to further improve the performance. For example, polyfunctional acrylate compounds such as trimethylolpropane trimethacrylate and polyethylene glycol diacrylate, or polyfunctional allyl compounds such as diallyl phthalate and triallyl triisocyanurate, and radical generators such as dicumyl peroxide and benzoyl peroxide. Alternatively, a masked isocyanate compound can be used in combination with a polyol such as polyethylene adipate, polytetrahydrofuran, or polycaprolactone. Furthermore, methacrylate resins produced using polymerizable compounds having functional groups that react with isocyanates, such as 2-hydroxyethyl acrylate, glycidyl acrylate, and 2-aminoethyl acrylate, as copolymerization components, generate isocyanate when heated. It is also possible to coexist a masked isocyanate compound. In addition, if the blowing agent in the expandable PVC layer is a chemical blowing agent that generates gas when heated, the plastisol of methacrylate resin may contain a compound that promotes the foaming of the chemical blowing agent. This is effective in increasing the difference in the unevenness of the sheet after heating and foaming and improving the design. Examples of these accelerators include urea, zinc oxide, zinc octylate, lead phthalate, cadmium stearate, and the like. In addition, it is also possible to mix into the methacrylate resin plastisol, if necessary, compounds commonly used as plastic compounding agents, such as fillers, colorants, flame retardants, stabilizers, and ultraviolet absorbers. On the other hand, the foamable soft PVC layer is made of PVC as a main component, and contains a plasticizer, a stabilizer, a foaming agent, and if necessary, a coloring agent, a filler, a flame retardant, etc. As PVC, a conventional homopolymer of vinyl chloride or a copolymer having a vinyl chloride component of 70% by weight or more and a degree of polymerization of 500 to 3000 is used.
In addition, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid ester copolymer, etc. can also be used in combination. As blowing agents, chemical blowing agents such as azobisisobutyronitrile, azodicarbonamide, paratoluenesulfonyl semicarbazide, dinitrosopentamethylenetetramine, paratoluenesulfonylhydrazide, 4,4'-oxybisbenzenesulfonylhydrazide, and sodium bicarbonate; Heat-expanded capsules such as liquefied gas microcapsules can be used. Formation of a foamable PVC layer on paper, cloth, asbestos, etc. may be carried out using a conventional coater such as a knife coater, rod coater, gravure coater, or screen coater. Screen printing is the preferred method for forming methacrylate resin plastisol on the expandable PVC layer because it allows for relatively thick coating, but other methods may also be used if they can be applied partially. It is not a restriction. It is also effective to previously form irregularities on the foamable PVC layer using a mechanical means such as an engraving roll, and then selectively apply methacrylate resin plastisol to the convex or concave parts. In addition, before applying this plastisol, foaming
Surface treatment printing, pattern printing, or flocking may be performed on the entire or partial PVC layer. After applying plastisol of methacrylate resin, a sheet with an uneven pattern is obtained by heating and foaming the sheet in a conventional apparatus such as a hot air circulation furnace or a hot wire furnace. This can be used as it is or by further high-level processing such as embossing, printing, and flocking to make a product decorative sheet. The decorative sheet obtained in this way has the highly foamed part covered with a strong methacrylate resin layer, and the foam layer underneath is soft and has a sense of mass, and is lightweight yet strong and stain resistant. It has characteristics not found in conventional decorative sheets. The present invention will be explained below with reference to Examples. In addition,
The number of parts used for each component is based on weight. Example 1 (See Figures 1 and 2) Plastisol having the composition shown below was applied to a thickness of about 200μ on flame-retardant paper 1, and heated at 140°C for 1 minute to remove azodicarbonamide. A gelled foamable sheet 2 in an undecomposed state was obtained. Polyvinyl chloride for plastisol 100 (weight average degree of polymerization 1300) Di-2-ethylhexyl phthalate 60 Heavy calcium carbonate 50 Azodicarbonamide 6 Na-Zn stabilizer 5 Titanium oxide 10 Mineral turpentine 5 Next, gelled foaming Base printing ink 3 was printed on the sheet by gravure printing and dried.
Next, Plastisol 4, a methacrylate resin with the following composition, was applied to the foam sheet by screen printing to a thickness of about 100 μm (Fig. 1) and heated at 210°C.
By heating and foaming for 90 seconds, a foamed decorative sheet as shown in FIG. 2 was obtained. Polymethyl methacrylate 100 (average particle 0.15 μ, average molecular weight 600000) Di-2-ethylhexyl phthalate 400 Titanium oxide 10 Fluorescent colorant 0.1 Silicic anhydride 5 The plastisol with the above composition contains 200 parts of di-2-ethylhexyl phthalate. After dispersing and mixing in a three-roll mill, remove 200
of di-2-ethylhexyl phthalate. Example 2 (See Figures 3 and 4) The base printing ink 5 was applied to the entire surface of the same foamable sheet 2 used in Example 1 using a gravure printing machine, and after drying, the foamable sheet was coated in an infrared heating furnace. After heating to such an extent that the foaming agent contained therein was not decomposed, an uneven pattern was applied using an embossing roll, and at the same time, valley stain printing 6 was performed. Plastisol 7 having the following composition was coated on this sheet (Fig. 3) and heated and foamed at 210°C for 90 seconds to obtain a foamed decorative sheet as shown in Fig. 4. Methyl methacrylate/ethyl acrylate/
Copolymer of acrylonitrile = 88/8/4 100 (particle size 0.24μ average molecular weight 1300000) Di-2-ethylhexyl phthalate 400 Silicic anhydride 5 Comparative example 1 Polymethyl methacrylate of the methacrylate resin plastisol used in Example 1 Polymerization degree 1600
A foamed sheet was obtained in the same manner as in Example 1 except that polyvinyl chloride for plastisol was used. Comparative Example 2 Same as Example 1 except that the polymethyl methacrylate of the methacrylate resin plastisol used in Example 1 was changed to a 50/50 copolymer of methyl methacrylate/butyl methacrylate (average molecular weight 680,000, average particle size 0.15μ). An attempt was made to obtain a foamed sheet using the same procedure, but the viscosity of the plastisol increased significantly and it was not possible to coat the PVC layer. Comparative Example 3 Example 1 except that di-2-ethylhexyl phthalate in the methacrylate resin plastisol used in Example 1 was changed to butylbenzyl phthalate.
A foamed sheet was obtained in the same manner as above. However, the plastisol solidified after one day and could no longer be coated. Comparative Example 4 (See Figure 5) A solution type surface treatment agent 8 of polymethyl methacrylate was applied to the entire surface of the same foamable sheet as used in Example 1 using a gravure printing machine, and foamed at 210°C. Immediately, an uneven pattern was applied using an embossing roll, and at the same time, valley stain printing 9 was performed to obtain a foamed sheet (FIG. 5). Example 3 (See Figures 6 and 7) Plastisol having the following composition was coated on an asbestos base material 10 to a thickness of 300 μm, and heated at a temperature at which the foaming agent did not decompose to solidify it and form the foamable sheet 11.
I got it. Polyvinyl chloride for plastisol 60 (degree of polymerization 1300) Polyvinyl chloride for thinning plastisol 40 (degree of polymerization 1000 average particle size 40μ) Di-n-octyl phthalate 32 Ba-Zn liquid stabilizer 3 Azodicarbonamide 3 Titanium oxide 5 Mineral turpentine 10 After printing a colored ink 12 containing polymethyl methacrylate as a main vehicle on the sheet 11 and drying it, a plastisol 13 having the following composition was coated and heated and foamed at 210°C for 2 minutes to form a foamed sheet (Fig. 7). ) was obtained. Methyl methacrylate/N-methylol acrylic 100 Amide = 80/20 copolymer (average molecular weight 1200000 average particle size 0.2μ) Dinonylphthalate 450 Feldspar fine powder 40 Example 4 (See Figures 8 and 9) Same as Example 3 After obtaining the foamable sheet 11, roughness is formed on the sheet using an engraved roll, and the raised portions are coated with plastisol 14 having the composition shown below, and heated at 130°C for 2 minutes to remove the plasticizer in the plastisol. It was transferred to the foamable sheet layer. Methyl methacrylate/α-methylstyrene/
Acrylonitrile = 85/10/5 copolymer 100 (average molecular weight 790000 average particle size 1.2 μ) Dioctyl adipate 150 Di-2-ethylhexyl phthalate 150 Red pigment 3 Next, Plastisol 15 with the following composition was applied with a rod coater (No. 8 ) and heated at 210° C. for 2 minutes to obtain a foamed sheet (FIG. 9). Polyvinyl chloride for plastisol 70 (degree of polymerization 1800) Polyvinyl chloride for thinning plastisol 30 (degree of polymerization 1000) Di-2-ethylhexyl phthalate 45 Ba-Zn stabilizer 3 Comparative example 5 Particle size of methacrylate resin in plastisol A foamed sheet was obtained by carrying out the same operation as in Example 3 except that the thickness was changed to 200μ. Comparative Example 6 A foamed sheet was obtained in the same manner as in Example 4, except that the molecular weight of the methacrylate resin in the plastisol was changed to 10,000. Comparative Example 7 (See Figures 10 and 11) After obtaining a foamable sheet 11 in the same manner as in Example 3, a foaming suppressing ink 16 containing a compound that suppresses the decomposition of a foaming agent is partially thermally transferred onto the upper part of the foaming sheet 11. death,
After that, the same PVC plastisol 15 used in Example 4 was coated on the entire surface (Fig. 10), and heated at 210°C for 3 hours.
A foam sheet with an uneven pattern (the first
Figure 1) was obtained. The characteristics of the foamed sheets obtained in the above Examples and Comparative Examples were evaluated, and the results shown in the table were obtained. The meaning of each test item in the table is as follows. Convex foaming ratio: Thickness of PVC layer after foaming / Thickness of PVC layer before foaming Concave Convex Difference: Convex thickness - Concave thickness / Convex thickness Blocking property: 10 x 10 mm square Align the convex part of the sample and place a 500g weight on top of it with a 1mm
After placing it on a thick steel sheet and leaving it for one week at 60°C ± 2°C, the force required to separate the bonded surface was measured using a tact tester. Durability: The foam sheet was fixed on a sample mount tilted at 45° to the vertical direction, and 100 kg of sand was dropped from a hopper 2 meters above the surface.The degree of damage to the foam sheet surface was visually observed. Evaluate in three stages: ○△× in descending order of number. Antifouling property: Attach a black rubber piece to the rolling surface of the driving wheel of the tapered abrasion tester, apply a load of 500 g, and roll the sample surface 3000 times. Visually check for dirt on the rolling surface of the sample. ○ in order of least
Evaluate in three stages: △×. Weather resistance: Place the sample in a Sunshine Weatherometer and evaluate the color of the sample (○△× in order of least discoloration) and surface cracks (○△× in order of least) after 1000 hours of arc radiation. . 【table】

[Brief explanation of drawings]

Figure 1 shows the sheet of Example 1 before foaming, Figure 2 shows the sheet after foaming, Figure 3 shows the sheet of Example 2 before foaming, and Figure 4 shows the sheet after foaming. FIG. 5 shows the sheet after foaming of Comparative Example 4,
FIG. 6 shows the sheet of Example 3 before foaming, FIG. 7 shows the sheet after foaming, FIG. 8 shows the sheet of Example 4 before foaming, and FIG. 9 shows the sheet after foaming.
FIG. 10 is a cross-sectional view of the sheet of Comparative Example 7 before foaming, and FIG. 11 is a cross-sectional view of the same sheet after foaming. 1,10...Base material, 2,11...Foamable soft material
PVC layer, 2', 11'... Soft PVC foam layer, 3,
5, 6, 9, 12...Printing ink, 4, 7, 1
3, 14...Methacrylate resin plastisol, 4', 7', 13', 14'...Methacrylate resin protective layer, 8...Polymethyl methacrylate solution type surface treatment agent, 15...PVC plastisol, 15' ...PVC protective layer.

Claims (1)

[Scope of Claims] 1 Base material A, a soft vinyl chloride resin foam layer B formed thereon, and a polymethacrylate component that covers all or part of the convex portions of this foam layer is 70% by weight or more, weight average A foamed sheet comprising a protective layer C obtained from a plastisol using a methacrylate resin having a molecular weight of 40,000 or more and an average particle diameter of 50μ or less. 2 After forming a foamable soft vinyl chloride resin layer on the base material, a methacrylate resin containing 70% by weight or more of a polymethacrylate component, a weight average molecular weight of 40,000 or more, and an average particle size of 50μ or less is applied on this layer. is partially coated with plastisol dispersed in a plasticizer for vinyl chloride resin that does not dissolve or swell the resin, and then heated to produce a foamed sheet in which the plastisol-applied areas become convex portions. A method for manufacturing a foam sheet.