JPS5941467B2 - Coating resin composition - Google Patents

Description

Detailed Description of the Invention The present invention provides low-temperature heat sealing properties, blocking resistance,
The present invention relates to a coating resin composition that provides a coating film with excellent slip properties.

Vinylidene chloride latex has been widely used in plastic film processing, cellophane processing, paper processing, etc. in the food packaging field due to its excellent gas barrier properties, low moisture permeability, chemical resistance, oil resistance, low-temperature heat sealability, etc. I started to be able to do it.

However, in order to apply plastic films coated with vinylidene chloride latex to general packaging applications,
(1) Excellent heat-sealability is required, with a strength of 501/15 mm or more when heat-sealed for 0.5 seconds at a load of 1υ and a temperature of 100°C, and (2) Suitability for packaging work and preservation of the coated film. Blocking resistance is very important when considering the properties of the film. If the blocking resistance is poor, not only will it be difficult to unwind the film from the roll, but if it is severe, the coated surfaces will come into close contact with each other and the coating film will be destroyed. ,
It becomes unusable.

Blocking resistance requires that latex coated surfaces do not block even after being left for 24 hours under a load of 5 Kv/25 d in an atmosphere of 40°C and 90% relative humidity, and (3) faster packaging speed. Accordingly, the slipperiness of the coating film is also required to have a coefficient of dynamic friction of 0.25 or less.

It is generally believed that heat sealability and blocking resistance, or heat sealability and slipperiness, are contradictory phenomena.

Conventionally, as a method for imparting blocking resistance, slipperiness, and heat sealability to a vinylidene chloride-based latex coated product, (a) the vinylidene chloride content is increased to enhance the crystallinity of the resin. (b) A suitable amount of a slip agent or anti-blocking agent such as talc, wax, or silica is added to the latex.

(→) A latex with good blocking resistance but poor low-temperature heat-sealing properties and a latex with poor blocking resistance but good low-temperature heat-sealing properties are blended in appropriate proportions to compensate for each other's deficiencies. methods, etc. have been proposed (Japanese Patent Application Laid-Open Nos. 48-12848, 1973-1)
No. 2849, JP-A-48-12850).

However, in the method (a), the deterioration of heat-sealing properties due to the crystallinity of vinylidene chloride cannot be avoided, and a contradiction arises in that the blocking resistance is improved.

In addition, in the method described above, these additives have poor compatibility with latex and are difficult to disperse uniformly, resulting in deterioration of the stability of the latex, deterioration of the color tone of the paint film, and furthermore, the transparency of the paint film. This may cause deterioration.

In the method (c), at least two or more types of latex must be blended, which creates the hassle of producing multiple types of latex. The present inventors believed that if a vinylidene chloride-based latex composition with excellent low-temperature heat-sealability, blocking resistance, and slipperiness could be obtained, it would have great utility value, and conducted extensive research. As a result, it was discovered that by introducing a small amount of propylene during polymerization of vinylidene chloride-based latex, the slipperiness and blocking resistance of the coating film were significantly improved, and the low-temperature heat-sealability was not inhibited, leading to the present invention. Ivy.

That is, the present invention includes 50 to 95 parts by weight of vinylidene chloride, 0.5 to 30 parts by weight of propylene, 4.5 to 20 parts by weight of one or more vinyl monomers, an unsaturated carboxylic acid, an acrylamide derivative, and Provides a coating film with excellent low-temperature heat-sealability, blocking resistance, and slipperiness, obtained by emulsion polymerization of 0 to 5 parts by weight of one or more monomers selected from hydroxyalkyl esters of unsaturated carboxylic acids. The present invention relates to a coating resin composition.

The latex of the present invention is obtained by ordinary radical emulsion polymerization, and the emulsifier may be an anionic emulsifier represented by commonly used alkylaryl sulfonates, alkyl sulfates, alkyl sulfonates, etc. Nonionic emulsifiers represented by polyoxyethylene monofatty acid ester, sorbitan monofatty acid ester, etc. can be used alone or in combination. As the polymerization catalyst, commonly used peroxide catalysts (1) such as hydrogen peroxide and tertiary butyl hydroperoxide, or persulfates (1) such as potassium persulfate and ammonium persulfate are used. Alternatively, a redox-based catalyst can be used in which (1) is combined with a reducing agent (!) typified by sodium bisulfite, Rongarit, etc., or (1) and (H).

Vinyl monomers copolymerizable with vinylidene chloride include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, glycidyl methacrylate, and acrylonitrile. , methacrylonitrile, vinyl chloride, styrene, etc.

Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, and fumaric acid.

Examples of acrylamide derivatives include acrylamide, crotonamide, N-methylolacrylamide, diacetone acrylamide, and the like.

Examples of the hydroxyalkyl esters of unsaturated carboxylic acids include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate. In the present invention, if the amount of vinylidene chloride exceeds 95 parts by weight, the crystallization rate will be high, the film forming temperature and heat sealing temperature will be high, and the shelf life of the latex will be shortened, making it impossible to put it into practical use.

If it is less than 50 parts by weight, the barrier properties, which are the characteristics of vinylidene chloride resins, will be lost. When the amount of propylene charged exceeds 30 parts by weight, polymerization productivity is low due to poor reactivity between the monomer and vinylidene chloride, which is not practical. If the amount is less than 0.5 part by weight, no improvement in blocking resistance or slipperiness can be expected.

In the present invention, the vinylidene chloride latex can be used as it is, or if necessary, a slip agent or anti-blocking agent such as silica, talc, mica, or wax may be added thereto.

Examples of the substrate to which the latex is applied include plastic films such as polypropylene, polyamide, and polyester, paper, and cellophane. EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples in any way. Parts and % in the examples mean parts by weight and % by weight.

In addition, the coating method of the vinylidene chloride latex in the examples, blocking resistance, film forming property, heat sealing property,
Evaluation of slipperiness and charging property was carried out by the method described below.

Latex Coating Method A urethane anchor coating agent is applied to a biaxially oriented polypropylene film whose surface has been subjected to corona discharge treatment using a Meyer rod, and dried at 105°C for 15 seconds in a hot air circulation type box dryer.

A latex with a solid content of 40% was applied thereon using a Meyer rod (coating amount: about 3 g/M2) and dried at 105° C. for 30 seconds in a hot air circulation box type dryer. The coated surfaces of a biaxially oriented polypropylene film coated with a blocking-resistant latex were placed together in an atmosphere of a temperature of 40°C and a relative humidity of 90%, and a load of 5 Ky/25~ was applied for 24 hours.
After standing for a period of time, peel off the film and judge according to the following criteria.

Grade 1: Peels off smoothly without any resistance.

Grade 2: It peels off smoothly after flicking it a few times with your fingertips.

Grade 3: There is some resistance, but it peels off without damaging the painted surface.

Grade 4: There are scratches on the paint film.

Grade 5: The coating adheres tightly and cannot be peeled off, and the base material will be torn if it is forcibly removed.

A latex-coated film prepared based on a film-forming latex coating method is judged to be good or bad if it has cloudiness.

○: The whole is transparent and no clouding is observed, which is good.

×: The coating film is cloudy even partially and is defective. Immediately after coating a heat-sealable latex-coated any-axis stretched polypropylene film or after aging at 40°C for 2 days, the width is 5CTfL.
, length 5? A sample is cut out, and the latex-coated surfaces are heat-sealed for 0.5 seconds at a temperature of 80 to 110° C. and a load of 1 using a bar-type heat sealer that heats both sides.

The sample is cut in a direction perpendicular to the heat-sealing surface to prepare three samples each having a width of 15 mm and a length of 50 mm for heat-sealing strength measurement. The heat seal strength of the sample is measured using a Tensilon tensile tester at a tensile rate of 30 (7 L/min).The heat seal strength is expressed as the average value of three measurements.Slip property 2' In an atmosphere of 55% relative humidity of C, the coefficient of dynamic friction when latex coated surfaces are overlapped is measured in accordance with ASTM D-1894-63 using an adhesion measuring device.

Charging property In an atmosphere of 20°C and 55% relative humidity, the latex coated surface and flannel cloth were rubbed at 400 rpm for 40 seconds using a Kyoto University Kaken type rotary static tester, and the electrostatic voltage generated at that time was measured. It is shown as a relative value when the charging voltage of the comparative sample is set to 1.

Example 1 In a stainless steel autoclave (capacity 21) equipped with a stirring device, 100 parts of deionized water, 3 parts of sodium dodecylbenzenesulfonate, 0.1 part of potassium persulfate, 0.3 parts of sodium hydrogen phosphate, and 0 parts of sodium sulfate were added. After charging .5 parts, the air inside the autoclave was sufficiently replaced with nitrogen gas, the autoclave was sealed, and the temperature inside the autoclave was adjusted to 30° C. while stirring.

-600m7ILHg when the internal temperature reaches 30℃
78 parts of vinylidene chloride, 5 parts of methyl acrylate, and 17 parts of propylene were charged and mixed for 30 minutes, then the internal temperature was raised to 50°C, and polymerization was continued for 20 hours after the internal temperature reached 5°C. continue. After 20 hours have elapsed, the internal temperature is cooled to 25°C, and the remaining unreacted monomers are released little by little.

Latex A was prepared by adding sodium dodecylbenzenesulfonate to the obtained latex to adjust the surface tension to 40 dynq.

The resin composition in this example was investigated by the following method.

The latex was salted out with methanol, and the precipitated resin was used to determine the vinylidene chloride content using the Siengel oxygen flask combustion method, and the methyl acrylate content using an infrared spectrophotometer. It was made from vinylidene-methyl acrylate copolymer.

The weight ratio to vinylidene chloride was determined using a standard curve of the absorbance ratio, and the weight ratio was corrected using the actual vinylidene chloride content determined from the Sienigel oxygen flask combustion method. The propylene content was determined by calculation. Latex A
The resin composition was 90% vinylidene chloride, 6% methyl acrylate, and 4% propylene.

In the same manner as Latex A, 90 parts of vinylidene chloride,
Comparative latex B was obtained by polymerizing 10 parts of methyl acrylate, adding sodium dodecylbenzenesulfonate to the obtained latex, and adjusting the surface tension to around 40 dyne.
We created and analyzed the composition.

A carnauba wax emulsion and a silica-based slip agent were added to the obtained latexes A and B (see Table 1), and the mixture was coated on a biaxially oriented polypropylene film, and the physical properties of the latex-coated film were measured. As is clear from the results in Table 1, by introducing propylene, a latex can be obtained that has improved blocking resistance and slipperiness, has good low-temperature heat sealability, and provides a coating film with reduced charging voltage.

Example 2 Latexes C, D, E, and F were prepared in the same manner as in Example 1 by changing only the monomer charge ratio, and their compositions were analyzed (see Table 2).

To these latexes, pure carnauba wax emulsion was added at 1% based on the solid content of the latex, and silica-based slip agent was added at 0.2% based on the solid content of the latex, and the mixture was coated on a biaxially stretched polypropylene film. Then, the physical properties of the latex-coated film were measured.

As is clear from the results in Table 2, by introducing propylene, a latex can be obtained that has improved blocking resistance and slipperiness, has good low-temperature heat sealability, and provides a coating film with reduced charging voltage. The amount of acrylic acid in the resin composition in this example was determined by the following method.

(a) Add methanol to the latex to precipitate the resin component, thoroughly dry it, and weigh 0.59 of the resin.

(b) Dissolve in 701 dimethylformamide.

(c) This solution is subjected to electrical conductivity titration using 0.1N-CO(CH3COO)2. (d) 0.1N-CO (CH3CO) required for the change from point a to point b in the drawing
O) Find 2X1rL1.

((e) The acrylic acid content is determined by the following formula. As is clear from the above examples, vinylidene chloride-based latex into which propylene monomer is introduced during polymerization has excellent blocking resistance, slipperiness, and low temperature properties. Excellent heat sealability,
Provides a coating film with reduced electrostatic voltage.

[Brief explanation of drawings]

The drawing shows a dimethylformamide solution of the resin at 0.1N-C.
It is a chart showing changes in titer and electrical conductivity when titrated with O(CH3COO)2.

Claims (1)

[Claims] 1 Vinylidene chloride 50-95 parts by weight, propylene 0.
5 to 30 parts by weight, 4.5 to 20 parts by weight of one or more vinyl monomers, one or more monomers selected from unsaturated carboxylic acids, acrylamide derivatives, and hydroxyalkyl esters of unsaturated carboxylic acids. 2 or more types 0~
A coating resin composition that is obtained by emulsion polymerization of 5 parts by weight and provides a coating film with excellent low-temperature heat-sealing properties, anti-blocking properties, and slip properties.