JPH0559342A - Adhesive for vinyl chloride resin - Google Patents

Abstract

PURPOSE:To subject adhesive comprising the aqueous dispersion of an urethane resin, the aqueous dispersion of an ethylenic resin, and the aqueous dispersion of an acrylic resin each in a specific ratio and giving good adhesivity to the opening of a bag or container for food produced of vinyl chloride resin films, etc. CONSTITUTION:The objective adhesive comprising (A) the aqueous dispersion of an urethane resin capable of thermally bonding vinyl chloride resins to each other preferably under a condition of 160-240 deg.CX2-6kg/cm<2>X1-3sec, (B) the aqueous dispersion of an ethylenic resin capable of thermally bonding vinyl chloride resins to each other preferably under a condition of 160-240 deg.CX2-6kg/ cm<2>X1-3sec, but incapable of doing so at an adhesivity of <=1kg/15mm, and (C) the aqueous dispersion of an acrylic resin having a glass transition temperature of >=40 deg.C in an A/B weight ratio of 2/1 to 4/1 and in a (A+B)/C weight ratio of 1/1 to 3/1 in terms of solid contents, respectively.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an adhesive for vinyl chloride resin, particularly a sealed packaging material such as bags and containers for foods and non-foods made of vinyl chloride resin film or sheet, which can be easily opened and transported. An adhesive for vinyl chloride resin that gives practically sufficient adhesive strength to the opening without damaging and opening during storage or storage, and does not cause blocking during storage as a scroll even when applied over the entire surface It is a thing.

[0002]

2. Description of the Related Art Vinyl chloride resins have been widely used as packaging materials for foods, detergents, etc. because of their excellent transparency and low gas permeability. However, in the case of the container having the shape illustrated in FIG. 1, the tray 1 is filled with the contents 2 at the time of use, and the vinyl chloride resin alone or the vinyl chloride resin and the base material such as paper and aluminum foil is provided in the opening. A method of applying a lid 3 made of a laminate of the above and heat bonding and sealing is adopted. Tray 1 in this sealing method
Since the vinyl chloride-based resin that constitutes the lid and the vinyl chloride-based resin that constitutes the lid 3 are melt-bonded, the adhesive strength is high, and a large force is required to remove the lid 3 from the tray 1 to take out the contents 2. The contents 2 popped out at the same time when the package was opened, and sometimes a blade had to be used to cut a part of the lid 3.

As a countermeasure against this, ethylene / vinyl acetate copolymer is previously laminated on the surface of the vinyl chloride resin constituting the lid 3, and the laminated film surface and the vinyl chloride resin constituting the tray 1 are melt-bonded. By doing so, a method for reducing the labor at the time of peeling was proposed and implemented. According to this bonding method, the force required for removing the lid 3 is certainly reduced, but it is not economically advantageous to laminate a copolymer having a thickness of 40 to 50 μm on the entire surface of the lid 3, and a different resin is used. However, since the lid 3 is attached, neither the lid 3 nor the tray 1 after removing the lid can be recovered as a recycled product.

In order to adhere the lid 3 to the tray 1, an adhesive is applied to the vinyl chloride sheet material in advance and dried to form a film, and then the tray 1 and the lid 3 are molded, and the film and the tray 1 are formed. Alternatively, there is a method in which the lid 3 is heat-bonded. If a commercially available rubber latex, polyvinyl acetate emulsion, acrylic resin emulsion or the like is used as the adhesive at this time, the force at the time of peeling off the lid 3 is reduced, but the adhesive force with the tray 1 is small and practical. It is not possible to obtain good adhesive strength. Therefore, if the thickness of the film is increased to such an extent that practical adhesive strength can be obtained, blocking will occur after winding and the tray 1 and the lid 3 cannot be molded.

Furthermore, when a vinyl chloride resin emulsion is used as an adhesive, the adhesive strength is too high and a large force is required to peel off the lid 3, and blocking is caused, which hinders the molding of the container and lid. Is brought.

On the other hand, in JP-A-56-123862, an aqueous dispersion prepared by blending ethylene-vinyl acetate copolymer resin particles with water and partially saponified polyvinyl alcohol is applied to a film surface and dried. Although a resin film having heat-adhesiveness has been proposed, according to this, although the blocking resistance is recognized, even when the adhesive is applied to both surfaces of the lid 3 and the tray 1, the adhesive strength between the adhesive surfaces is high. 350-495
It is as low as g / 20mm and poor in practicality. It is difficult to limit the practical adhesive strength depending on the shape of the tray 1 and the lid 3, the thickness of the sheet, the presence or absence of fitting, etc., but it is generally 1 to 2.5 kg / 15.
mm width.

[0007] Further, Japanese Patent Laid-Open No. 59-78278 discloses a practical use in which peel strength at 20 ° C. is 800 to 2500 g / 15 mm width, which is easy to peel by hand, but does not peel by impact. 15% to 85/5 by solid content weight ratio (1) / (2) of (1) an aqueous dispersion of a vinyl chloride resin and (2) an aqueous dispersion of an ethylene resin, which gives excellent adhesive strength. Liquid adhesives formulated in proportions are described. However, this method uses (1) / (2) = 50/50 as a boundary,
If it is more than that, blocking tends to occur, and if it is less than that, the adhesion strength of the coating film to the vinyl chloride resin is low.

Further, the aqueous dispersions of vinyl chloride resins currently on the market are poor in water resistance of the film obtained by coating and drying them, and when they are immersed in water at room temperature, they are remarkably whitened. When using it, partially coat it on a vinyl chloride resin sheet and dry it to form a film,
The lid or tray is formed so that the film portion is located at the heat-bonded portion between the lid and the tray, and heat-bonded. However, at this position, when the lid or tray is molded, the vinyl chloride resin sheet material shrinks, causing a gap, and it sticks out to a place that is not a heat-bonding site, and the moisture of the filled contents adheres to it. There is a problem of whitening the sheet material.

On the other hand, if the coating area is made small so as not to stick out, sufficient adhesive strength cannot be obtained, or if it deviates from the heat-bonded portion even a little, adhesive failure will occur, and it will be adjusted according to the size of each container. The current situation is that various problems remain, including the cost aspect, such as having to prepare a gravure plate roll for applying adhesive (plate roll for part coat). Long-awaited.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and to provide a hermetically sealed packaging material such as a bag or a container with a vinyl chloride resin film or sheet,
It is easy to open and gives practically sufficient adhesive strength that does not break during transport or storage and does not open, and does not cause blocking during storage as a scroll even when applied over the entire surface. It is to provide an adhesive for vinyl resins.

[0011]

[Means for Solving the Problems] The inventors of the present invention have found that in an aqueous dispersion of urethane resin of 100 parts by weight in terms of solid content, an aqueous dispersion of ethylene resin in a proportion of 25 to 50 parts by weight in terms of solid content. After the addition, an adhesive obtained by adding an aqueous dispersion of an acrylic resin having a glass transition temperature of 40 ° C. or more to the total solid content of 100 parts at a solid content of 33 to 100 parts has the above-mentioned problems. The present invention has been achieved by finding that an excellent effect of solving the above problem is exhibited.

That is, the adhesive for vinyl chloride resin according to the present invention is (A) an aqueous dispersion of urethane resin, (B)
It is composed of an aqueous dispersion of an ethylene resin and (C) an aqueous dispersion of an acrylic resin having a glass transition temperature of 40 ° C. or higher, and each has a solid content of (A) / (B) = 2/1 to 4
/ 1, (A) + (B) / (C) = 1/1 to 3/1.

The present invention will be described in more detail below. (Urethane-based resin) The aqueous dispersion of the urethane-based resin used as the component A in the adhesive of the present invention includes polyisocyanates (aromatic polyisocyanates, aliphatic polyisocyanates, partial carbodiimide-modified or isocyanurate-modified products thereof, Free isocyanate-containing prepolymer by reaction of polyfunctional active hydrogen compound with polyfunctional active hydrogen compound (water, low molecular weight polyol,
Polymer polyol [Water of alkylene oxide, low-molecular polyol, polyether polyol having a structure added to polyamine, polymer polyol by reaction of polyether polyol and ethylenically unsaturated monomer, polycarboxylic acid and low-molecular polyol Aqueous dispersions of various polyurethanes as reaction products with polyester polyols, etc. by reaction with polyamines), polyamines, etc .; Polyurethanes and ethylenically unsaturated monomers (vinyl acetate, styrene, acryl) mainly containing these polyurethanes Examples thereof include aqueous dispersions of a mixture of an acid or its ester, methacrylic acid or its ester, ethylene, vinyl chloride, vinylidene chloride, etc., polyester, epoxy resin and the like. Among these, particularly 160 to 240 ℃ × 2
Those capable of thermally adhering vinyl chloride resins to each other under the condition of ˜6 kg / cm ² × 1 to 3 seconds are preferably used. Commercial products that meet this definition include: No. 8481 manufactured by Miwa Research Laboratory, Billock 9L006 manufactured by Kanebo NSC, and R manufactured by ICI Resin Co.
9619, R9314 and the like can be mentioned.

(Ethylene-based resin) The aqueous dispersion of ethylene-based resin as the component B imparts practically easy peelability to the adhesive composition of the present invention. In particular, an aqueous dispersion of polyethylene; ethylene and Aqueous dispersion of copolymer with ethylenically unsaturated monomer other than ethylene; polyethylene-based copolymer with polyethylene as a main component, polymer of ethylenically unsaturated monomer other than ethylene, polyester, polyurethane , An aqueous dispersion of a mixture with an epoxy resin, etc. are exemplified, and among these, particularly 160 to 240 ° C ×
Even if the vinyl chloride resins are heat-bonded to each other under the condition of ^{2 to} 6 kg / cm ² × 1 to 3 seconds, the adhesive strength of 1 kg / 15 mm or less, which cannot be substantially heat-bonded, is preferably used. ..
Commercial products that meet this definition are No.434 manufactured by Miwa Research Institute.
0, Central Rika Kogyo GLZ3410, Toyo Morton AD34
5 etc.

(Acrylic resin having a glass transition temperature of 40 ° C. or more) An aqueous dispersion of an acrylic resin having a glass transition temperature of 40 ° C. or more as the C component is resistant to sheet rolls and the like after the adhesive of the present invention is applied and dried. It gives blocking property,
Specifically, an aqueous dispersion of polyacrylic acid ester or polymethyl methacrylate; an aqueous dispersion of a copolymer of acrylic acid ester or methyl methacrylate and an ethylenically unsaturated monomer other than these; polyacrylic acid ester or poly Examples thereof include aqueous dispersions of methyl methacrylate as a main component, a mixture of these with the copolymer, an acrylic acid ester or an ethylenically unsaturated monomer other than methyl methacrylate, polyester, polyurethane, and an epoxy resin. And within these,
Particularly, those having a glass transition temperature of 40 ° C. or higher are preferably used. Commercial products that meet this definition include A-645, A-633R, and A-640 manufactured by ICI Resins. An acrylic resin aqueous dispersion having a glass transition temperature of less than 40 ° C. is not suitable for the present invention because the rolled sheet-like material causes blocking.

(Blending Ratio of the Three Resin Components A to C) The aqueous dispersion liquid of the three resins A to C is (A) / (B) = 2 in terms of the weight ratio of each solid component. It is required that / 1 to 4/1 and (A) + (B) / (C) = 1/1 to 3/1. Here, when (A) / (B) is less than 2/1, practically sufficient adhesive strength cannot be obtained, and this is 4/1.
If it exceeds, the adhesive strength will be too strong to be easily opened. Similarly, if (A) + (B) / (C) is less than 1/1, a practically sufficient adhesive strength cannot be obtained, and if it exceeds 3/1, the rolled sheet-shaped material is blocked. Will be caused.

(Other Components) In addition to the above-mentioned three resin components, the adhesive of the present invention contains a plasticizer, a fusing agent, a leveling agent, a wetting agent, an antifoaming agent, an antiseptic agent, and an ultraviolet ray, if necessary. Absorbers, colorants, antioxidants, fillers, stabilizers, flame retardants and the like can be added.

(Coating Method) In order to coat the sheet-like material with the adhesive according to the present invention, a dipping method, a spray method, a flow coating method, a gravure method or the like is adopted, whereby a smooth surface solidified film is formed. It As a substrate to be coated, it is particularly useful for vinyl chloride resin molding sheets and films that are inferior in ease of peeling due to heat adhesion, and its shape is not only the tray shown but also bags, blister containers, cups with lids. It can be applied to containers.

The sheet of vinyl chloride resin coated with the adhesive of the present invention is dried and solidified under the condition that it does not undergo thermal deformation. Therefore, in the case of a rigid vinyl chloride sheet, it is 40 to 140 ° C, preferably 80 to 120 ° C for several seconds to
Dry for tens of seconds. The average film thickness of the solidified film depends on the application of the molded product,
Although it varies depending on the shape and the like, it is usually 0.5 to 10 μm, preferably 1 to 5 μm.

[0020]

EXAMPLES The present invention will be described more specifically below based on Examples and Comparative Examples. Examples 1-3, Comparative Examples 1-4 and 6-7. No.84 manufactured by Miwa Research Institute as an aqueous dispersion of urethane resin of component A
81 (solid content 40% by weight), No.4340 (solid content 45% by weight) manufactured by Miwa Research Institute as an aqueous dispersion of component B ethylene resin, and ICI resin as an aqueous dispersion of component C acrylic resin A645 (glass transition temperature 49 ℃, solid content 40
(% By weight) were mixed in the proportions shown in Table 1 to prepare each adhesive.
Each of them was applied to the surface of a hard vinyl chloride resin sheet with a thickness of 200 μm so that the solid content would be ² g / m ^2.
It was dried by heating for 2 seconds to form a film on the sheet.

Example 4. A film was formed in the same manner as in Example 2 except that GLZ3410 (solid content 40%) manufactured by Chuo Rika Kogyo Co., Ltd. was used instead of No.4340 manufactured by Mitsuba Laboratory as the aqueous dispersion of ethylene resin. did.

Embodiment 5. In Example 2, instead of No. 8481 manufactured by Miwa Research Institute as an aqueous dispersion of urethane resin, VILLOCK 9L006 manufactured by Kanebo NSC (solid content 40%) was used.
%) Was used to form a film in the same manner.

Comparative Example 5. The same procedure as in Example 2 was repeated except that A623 (glass transition temperature: 10 ° C., solid content: 35% by weight) manufactured by ICI resin was used instead of A645 manufactured by ICI resin as the aqueous dispersion of acrylic resin. Formed.

With respect to each of the above-mentioned films, the transparency, water whitening resistance, blocking resistance, peeling recovery property and adhesive strength were measured by the following methods. As a result, there was no difference in transparency, water whitening resistance, and peeling recovery property in each case, and only the blocking resistance and the adhesive strength showed the differences as shown in Table 1.

-Transparency: Compared with the uncoated sheet, it was visually judged based on the following criteria. ○ ・ ・ ・ No big difference, △ ‥ Slightly inferior, × ・ ・ ・ Opaque.・ Water whitening resistance: Uncoated sheet is immersed in water at 20 ℃ for 24 hours.
After a lapse of time, the product was taken out, dried in a room, and then visually judged according to the following criteria. ○: Almost no change, △: Whitening, ×: Whitening.・ Peeling recovery: 25g of uncoated sheet and 25g of coated sheet
3.5-inch diameter 2 with a nip spacing of 200 μm and temperature controlled at 00 ℃
It was put in between the main rolls, kneaded for 2 minutes, and then the state when peeled from the rolls was observed and judged according to the following criteria. ○ ・ ・ ・ Peeled state similar to uncoated sheet 50g, △ ・ ・ ・ Slightly taken by roll, × ・ ・ ・ Peeling is not possible.

Blocking resistance: An uncoated sheet is superposed on a coated sheet, left under a load of 5 kg / cm ² for 24 hours in an atmosphere of 35 ° C., left at room temperature for 2 hours, and then observed. It was judged according to the standard. ○: Almost no blocking, △: Blocking marks remain, ×: Blocking is too great to peel.

Adhesive strength: 300 μm thick on the coated sheet
Place a rigid vinyl chloride resin sheet of m, and use a heat sealer manufactured by Toyo Seiki Co., Ltd. from below, 160 ℃, 200 ℃, 240 ℃
Each sheet was heat-bonded at each temperature of, a sealing pressure of 4 kg / cm ² , and a sealing time of 2 seconds, and the obtained adhesive sheet was cut into a width of 15 mm. This is measured at 20 ° C, relative humidity 65%, and pulling speed 300mm / min with the AD-5 type peeling checker manufactured by Yasukawa Shoji.
Peeling was performed at 80 degrees to obtain a value of adhesive strength.

[0028]

[Table 1]

Example 6. The adhesive prepared in Example 2 on the surface of a hard vinyl chloride resin sheet having a thickness of 200 μm (A component: 75 parts by weight, B component: 25 parts by weight, C component: 70 parts by weight)
Was applied so as to have a solid content of 2 g / m ² and then dried at 80 ° C. for 20 seconds to obtain a film. Immediately after heating this sheet at 200 ° C for 25 seconds, it is vacuum-formed and the length is 110 mm and the depth is 10 m.
m, the width of the sealing part was 6 mm, and the four corners were rounded with a circle having a radius of 10 mm.

On the other hand, a tray made of hard vinyl chloride resin having a wall thickness of about 300 μm, which has a length of 107 mm, a depth of 30 mm, a seal portion width of 5 mm, and four corners rounded by a circle having a radius of 10 mm, is prepared. Put 150 g of umeboshi in this, fit the above lid, and heat the lid and tray seal parts at 200 ° C, 4 kg / cm ² , for 1 second using a plate-shaped heat sealer with a length and width of 250 mm. I sealed it. Keep this sealed container horizontal, height 70 cm
When dropped on the wooden floor, no peeling of the seal area was observed. Further, when the lid of the hermetically-sealed container caught a portion protruding from the corner of the tray and was peeled off from the tray, the lid was easily removed.

[0031]

EFFECTS OF THE INVENTION When the adhesive of the present invention is used as an adhesive for easy peeling by heat-adhesion of vinyl chloride resin sheet or the like, 1) it is easy to open the lid and the seal portion such as the container or bag. 2) To give practically sufficient adhesive strength that does not damage during transportation. 3) It has excellent water resistance and food resistance. 4) It is safe for food hygiene because it does not use a solvent. 5) It has excellent transparency and blocking resistance, and can be applied to the entire surface, so there is no need for a part coat, and there is no need to worry about misalignment during molding. Since there is no need to prepare a gravure roll, the improvement effect in terms of quality and cost is great.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a tray which is one application of the adhesive of the present invention.

FIG. 2 is a vertical cross-sectional view showing a state in which the tray of FIG. 1 is filled with contents and then the lid is adhered using the adhesive of the present invention.

[Explanation of symbols]

 1 ... tray, 2 ... contents, 3 ... lid.

Claims (1)

[Claims] 1. An aqueous dispersion of a urethane resin (A),
(B) An ethylene-based resin aqueous dispersion and (C) an acrylic-based resin aqueous dispersion having a glass transition temperature of 40 ° C. or higher, each of which has a solid content of (A) / (B) = 2 /
1 to 4/1, (A) + (B) / (C) = 1/1 to 3/1
An adhesive for vinyl chloride resins, characterized by being