JPS62256871A - Vinylidene chloride copolymer latex - Google Patents

Abstract

PURPOSE:To improve the blocking resistance and the adhesion of a coating film when applied to plastic films, etc. and to improve the resistance to a treatment with hot water after heat seal, by copolymerizing vinylidene chloride with methyl methacrylate, a monomer having a nitrile group and a monomer copolymerizable with vinylidene chloride. CONSTITUTION:Latex contains a vinylidene chloride copolymer composed of 85-93wt% unit (a) derived from vinylidene chloride monomer, 6-14.5wt% unit (b) derived from methyl methacrylate monomer, 0.5-4wt% unit (c) derived from a monomer having a nitrile group and copolymerizable with vinylidene chloride, and 0-2wt% unit (d) derived from a monomer copolymerizable with vinylidene chloride and other than the components (a), (b) and (c). The latex contains 4-30wt% polymer soluble in an eluent of tetrahydrofuran and methanol (60:40) and 4-60wt% polymer insoluble in an eluent of tetrahydrofuran and methanol (90:10) as resin components.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is coated onto a plastic film etc. and has excellent blocking resistance, adhesion and barrier properties, and is also resistant to hot water treatment after heat/rolling. This invention relates to a vinylidene chloride copolymer latex that provides a coating film with excellent resistance.

[Conventional technology and its problems]

Vinylidene chloride copolymer latex has a coating film with excellent barrier properties and chemical resistance, and is coated onto plastic films and is widely used in the food packaging field.

However, if it is rolled up immediately after coating, a blocking phenomenon may occur, and when it is filled with food,
When hot water treatment is applied immediately after bag making by heating for sterilization, there is a problem that the coating film becomes white and deteriorates in quality (hereinafter referred to as boil whitening at the boiling part). In order to prevent these problems, there is a method of increasing the crystallization rate immediately after film formation and immediately after heat/heating by using a copolymer with a high content of vinylidene chloride. μ54+,
It has been proposed in issue r. However, these methods have the disadvantage that when printing on the coating film, the adhesion between the printing ink and the coating film is insufficient, resulting in the printing material easily peeling off and resulting in poor appearance. . In addition, a method for producing a coating film with good printability and blocking resistance by heat treatment after coating is disclosed in JP-A-10-2! ;001f/, but it was difficult to obtain one with well-balanced performance under normal coating conditions.

On the other hand, the adhesion between printing ink and coating improves as the number of nitrile groups in the polymer increases. However, polymers containing a large amount of nitrile groups have a slow crystallization rate, and therefore cannot provide satisfactory performance in terms of blocking resistance and sealing part boiling whitening resistance.

Therefore, the present inventors conducted intensive studies to find a high-barrier vinylidene chloride-based copolymer latex that satisfies all of the requirements of prong resistance, seal part boil whitening resistance, and adhesion, and found that it contains many nitrile groups. The inventors have discovered that a vinylidene chloride-based copolymer latex having the desired performance can be obtained by controlling the zl of a polymer containing a large amount of all units derived from the polymer and vinylidene chloride, and have arrived at the present invention.

[Means to resolve the deadlock]

That is, the present invention provides: a) unino derived from vinylidene chloride monomer) l#~
931i (preferably rr ~ 92% by weight) b) methacrylic tank methyl monomer-derived unit ~/1. !
C) Units derived from monomers copolymerizable with vinylidene chloride having a nitrile group (preferably 72% by weight)
d) Latex containing a vinylidene chloride copolymer consisting of 0 to 2% by weight of units derived from monomers copolymerizable with vinylidene chloride other than those listed in a), b), and c) K above. As a resin component, a polymer (polymer A) that is soluble in an eluent in which tetrahydrofuran and methanol are mixed at a ratio of 10 to qO (polymer A) v < zz 30% by weight or less, and insoluble in an eluent that is mixed at a ratio of 90 to IO. The present invention relates to a vinylidene chloride-based copolymer latex characterized by having a polymer (polymer B) of 1M or more and 60% by weight or less.

The amount of units derived from a monomer having a nitrile group contained in polymer AK is 2% by weight with respect to polymer ALvfK.
It is preferable that the content of the polymer B is less than or equal to 0% by weight.
The amount of units derived from monomers having nitrile groups contained in Polymer B is preferably 1% by weight or less, based on the weight of Polymer B.

Here, the amounts of Polymer A1 and Polymer B were determined by the following solubility fractionation method.

"Solubility fractionation method" The polymer obtained by coagulating latex in methanol and drying is dissolved in tetrahydrone run, and the polymer obtained by coagulating the latex in methanol is dissolved in tetrahydrone run.
．． /ws glass bulbs were added and heated to evaporate to dryness.

The polymer-coated glass spheres are packed into a glass column, and the column temperature is maintained at 3°C. From the upper end of this column, an eluent containing a mixture of tetrahydrofuran and methanol at a ratio of 60 to tIo flows upstream, receives the eluate coming out from the lower end of the column, and dries it to determine the lt''k of the dissolved polymer. This is taken as the amount of Polymer A. Next, from the top of the above column, an eluent 'Thfil~ of tetrahydrofuran and methanol with qO:10 is received, and the eluate coming out from the bottom of the column is dried. The amount of polymer obtained was measured. Both amounts were subtracted from the amount of polymer B coated on the glass beads.
The amount of

NC analyzer (manufactured by Sumitomo Chemical) containing units derived from monomers containing nitrile groups contained in polymers
Calculated from K and converted from 9N including capital.

Sh6niger's r! ! It was calculated by converting the chlorine content fi determined by the plain flask combustion method.

The amount of units derived from methyl methacrylate contained in the polymer was determined using a gas chromatograph of all the gas generated by thermally decomposing the polymer using a Curie point pyrolyzer.

As the monomer copolymerizable with vinylidene chloride having a nitrile group in the present invention, acrylonitrile or methacrylonitrile is preferable.

Monomers other than vinylidene chloride, methacrylic m-methyl, and monomers having a nitrile group that can be copolymerized with vinylidene chloride include ethylenic α,β-unsaturated carboxylic acid such as acrylic acid, methacrylic acid, or itacon vinegar. Alkyl esters (excluding methyl methacrylate) or hydroxyalkyl esters of these unsaturated carboxylic acids, amide compounds of ethylenic α,β-unsaturated carboxylic acids such as acrylamide, vinyl esters such as vinyl chloride, vinyl acetate, etc. There are vinyl ethers such as vinyl methyl ether, allyl esters such as allyl ester, and allyl ethers such as methyl ether.

If the amount of units derived from vinylidene chloride contained in the copolymer is less than lrj fFl, satisfactory gas barrier properties cannot be obtained. Moreover, if the amount is more than 11% by weight of 93%, satisfactory film forming properties cannot be obtained.

Further, the amount of units derived from monomers having nitrile groups contained in the total copolymer is 0. ! r 7K Jt%
If it is less than this, satisfactory adhesion cannot be obtained. On the other hand, if the weight percentage exceeds 5% by weight, the amount of nitrile groups included in the polymer A and B will increase, and satisfactory sealing part whitening resistance and blocking resistance will not be achieved.

The larger the amount of 2) IJ groups contained in the polymer,
Easily soluble in mixed solvents with a high methanol ratio.

Furthermore, polymers containing many units derived from vinylidene chloride are only soluble in mixed solvents with a low methanol ratio. Therefore, the polymer Al- contains a large amount of polymer having a large number of lyl groups, which greatly contributes to adhesive properties.

Therefore, if Polymer 8 contains less than 1 nitrile derived from a monomer having a nitrile group, or if the amount of Polymer A is less than q'@''ti of the total polymer amount, it is not satisfactory. Adhesion cannot be obtained. Also, polymer AK
If the number of units derived from the 1iiF & body having a nitrile group included is more than 20 units relative to the amount of polymer A, or if the number of rings in polymer A is 30 units of the total polymer ②! If the amount is more than 1, satisfactory blocking resistance and sealing portion boil whitening resistance cannot be obtained.

Polymer B contains a large amount of polymer having many units derived from vinylidene chloride, so the crystallization rate e
It has a large contribution to reducing Ml.

Therefore, if Polymer B contains more than 7% by weight of units derived from monomers having IJ groups, or if the amount of Polymer B is less than 1% by weight of the total polymer amount, the condition is satisfied. Unable to obtain sufficient blocking resistance and sealing part boiling whitening resistance.

Furthermore, if the claws of polymer B exceed 1% by weight of tO of the total polymer, the film forming properties will be poor and a satisfactory gas barrier property will not be obtained.

As a method for producing the vinylidene chloride copolymer latex of the present invention, the following method is preferably used.

■ A method in which vinylidene chloride and methyl methacrylate are added to the polymerization system to allow the reaction to proceed under sufficient pressure, and then vinylidene chloride and acrylonitrile are added to allow the reaction to proceed. Or, reverse the order of addition of this and the 1000 ml mixture.

■ A method of completely mixing latex made from vinylidene chloride, methyl methacrylate and other vinyl monomers with latex made from vinylidene chloride, acrylonitrile and other vinyl copolymers.

〔Example〕

The present invention will be described in detail below with reference to examples. In the examples, the Japanese text 1-t% simply refers to parts by weight or % by weight.

Example / In a pressure-resistant reactor with glass lining, 7fi water,
After charging 0.2 parts of alkylbenzenesulfonic acid sorter and 1 part of persulfuric acid and degassing, the temperature of the contents was maintained at 1 (1)°C. In a separate container, vinylidene chloride (VDC) f/part, methyl methacrylate (MMA)
A monomer mixture was prepared by weighing and mixing 9 parts. The entire IO portion of the monomer mixture was charged into the reactor, and the reaction was allowed to proceed under stirring. After confirming that the reaction had progressed sufficiently by lowering the internal pressure in the reactor, a 70% aqueous solution of alkylbenzene sulfo/acidic soda was completely injected into the second part, and all the remaining ffi of the rear-loading monomer mixture was injected at once.

After confirming that the internal pressure in the reactor has sufficiently decreased and the reaction has proceeded sufficiently, dissolve persulfuric acid, IJum QO/part, hydrogen sulfite, IJum o, o o s part in water. Thereafter, a mixture of q parts of vinylidene chloride and 1 part of acrylonitrile (AN) was injected under pressure.Then, the reaction was allowed to proceed at 1, when the internal pressure was sufficiently lowered. The latex thus obtained was treated with a 75% alkylbenzenesulfonic acid sorter to adjust the gas-liquid surface tension at 20° C. to 112 dyne/cn1. The composition of all the polymers in the latex thus obtained was as follows as a result of analysis.

VDC9/, 0 parts by weight MMA 74% by weight AN /J weight As a result of performing a solubility fractionation method on this latex,
Mixing ratio of tetrahydrofuran and methanol is 60:11
The polymer soluble in the eluent of No. 0 was 7.0% by weight of the total polymer, and contained 7 units derived from acrylic nitrile. Furthermore, the polymer insoluble in the eluent with a mixture ratio of tetrahydrofuran and methanol of qO to IO was loB% of the total polymer, and only 01M units of units derived from acrylonitrile were contained therein. It was the latex of the present invention.

This latex axially stretched nylon film (/jμ)
The coating was applied so that the dry coating amount was sgβ (7.! It was dried for 30 seconds in an oven kept at 0°C.) This coated product had the pronking resistance and sealing part boil whitening resistance as defined in the present invention. The properties, adhesiveness and barrier properties were evaluated as follows.

(1) Blocking resistance After coating and drying, the coated product was layered so that the grown VC coated surface was in contact with the high-density polyethylene film (/Qμ), and a pressure of /I'g/cA was applied from above at 110°C. ! O%R
It was left for 20 hours under an H atmosphere. Thereafter, the film was peeled off and the coated surface was observed to determine blocking resistance.

The criteria for evaluation were as follows: ◎ marks for all cases with no traces of crimping, ○ marks for those with slight marks, and X marks for cases with strong marks.

(2) Boil whitening resistance of the seal area After aging the coated product for 2 days in an oven kept at 110"C, a polyethylene film of K11) μm was layered on the coated surface using a heat-on roll tester (manufactured by Tester Sangyo).
The mixture was heated at 770° C. for 7 Kg/ctA −/second. Immediately thereafter, the film was immersed in VC hot water at 9/°C for 30 minutes, and the degree of whitening of the film taken out was examined to evaluate the boil whitening property of the sealed portion.

The evaluation criteria were as follows: No whitening at all was marked with ◎, slight whitening was marked with ○, and cases with clear whitening were marked with X.

(3) Adhesion After the coated product was aged for 2 days in an oven kept at 0°C, a dry coating amount of K Q N C-S 'l' N white ink (Toyo Ink) was applied on the coated film surface. is 2g/lr
? 7 in an oven kept at 30℃.
Dry for a minute. Thereafter, the ink was subjected to a sellotape peeling test to determine ink adhesion. The criteria for judgment is: ◎ indicates that the product does not peel off at all, and ○ indicates that it does not peel off at all.
Those in which peeling was clearly observed were marked with an X mark.

(4) i! ! Elementary transmittance After the coated material was aged for 2 days in an oven maintained at 0°C, the ASTM D-391! -according to r/, 0X
TRAN-100 (Fil+dernCorItro
Oxygen permeability was measured under conditions of 20° C. and 100% relative humidity. The measured value is AE/-・atm・j
1711. Displayed in units of .

These evaluation results are shown in Table 7. In addition, the following latex was analyzed on the same machine as Example/, and the performance was t12111.
I did i. The results are shown in Table 7.

Example Coratex A Into the same reactor as Example/, 7 parts of water, 7 parts of alkylbenzenesulfonic acid Nog a, and 0.1 part of sodium persulfate were charged, and the temperature was maintained at jO″C.

Next, 91 parts of vinylidene chloride and 9 parts of methyl methacrylate were measured and mixed in a separate container, and the entire amount was charged into the reactor. Thereafter, the entire reaction was allowed to proceed under stirring until the internal pressure was sufficiently lowered. Sodium alkylbenzenesulfonate was added to the latex thus obtained to adjust the gas-liquid surface tension at 0° C. to 2 dyn·.

Latex B Latex A monomer mixture k i Vinylidene 9
It was obtained using the same formulation as Latex A, except that 1 part and 1 part of acrylonitrile were used.

Latex A and latex Bk solid content ratio! 3. The desired mixed latex was obtained by mixing at a ratio of j to no≦j.Example 3 Latex C used latex A of Example/, and latex D consisted of vinylidene chloride rj moiety and acrylonitrile/js. It was obtained using the same formulation as Latex A from a seven-mer mixture.

Solid content ratio of latex C and latex D'! j vs./j
The desired mixed latex was obtained.

Comparative Example 1 Vinyl chloride 79/part, methacrylic acid methyl 7, j part,
A desired latex was obtained from a monomer mixture consisting of 7.5 parts of acrylonitrile using the same formulation as Latex A in Example 1.

Comparative Example: In a reactor similar to Example 1, Ir, r parts of water, 7 parts of alkylbenzenesulfonic acid, and 0.1 part of sodium persulfate were added.
After keeping the temperature at 55° C., the entire amount of a monomer mixture consisting of 3.3 parts of vinylidene chloride and 7.3 parts of acrylonitrile was charged into the reactor. Immediately thereafter, a monomer mixture consisting of 77 J parts of vinylidene chloride and 7.2 parts of methyl methacrylate was quantitatively increased continuously over 75 hours, and the reaction was allowed to proceed until the internal pressure was sufficiently lowered to obtain the desired latex.

Comparative Example 3 Latex E In a reactor similar to Example/, 10 parts of water, 0.0 parts of sodium alkylbenzenesulfonate, 7W+, 0.1 parts of sodium persulfate.
The temperature was maintained at 55°C. In another container, 9/6 parts of vinylidene chloride and 70 parts of the monomer mixture were charged into an acrylonitrile reactor, and reaction f: was allowed to proceed with stirring.

After confirming that the reaction had sufficiently progressed by lowering the internal pressure in the reactor, 6 parts of a 10% aqueous solution of sodium alkylbenzenesulfonate was introduced under pressure, and then 7 parts of the monomer mixture was continuously quantified over an hour. After reaching normalization, the reaction was allowed to proceed until the internal pressure was sufficiently reduced to obtain the desired latex.

Latex F The monomer mixture of Latex E was mixed with vinylidene chloride 9/,
j part, methacrylic brewed methyl otsu part, acrylonitrile 43
parts, methacrylic acid (MAA) / parts.
It was obtained using the same formulation as Latex E.

The solid content ratio of Latex E and Latex F is 20:1.
By mixing at a ratio of 0, the desired mixed latex was obtained.

The evaluation results for the above latex are summarized in Table/.

As is clear from the table, Examples of the present invention/, - and 3
All of the vinylidene chloride copolymer latexes have excellent blocking resistance and sealing part boiling whitening resistance, and have good adhesion. It also shows excellent performance in terms of oxygen permeability.

On the other hand, the quantitative ratio of each monomer unit obtained by analysis of the entire polymer of Comparative Example/C is the same as that of Example C, and the mixing ratio of tetrahydrofuran and methanol is O to 1.
Polymers that are insoluble in the eluent of 0 are within the scope of the present invention and exhibited good anti-blocking and anti-seal boil whitening properties.

However, since there were few units derived from acrylonitrile contained in the polymer soluble in the eluent of OtsuO and 11Q, satisfactory adhesion could not be obtained.

In addition, Comparative Example 1 also shows that unisotil derived from acrylonitrile contained in the polymer soluble in the eluent of O vs.
Since t was small, sufficient adhesiveness could not be obtained. or,
Since there is no polymer insoluble in the 90:IO eluent,
Satisfactory blocking resistance and seal portion boil whitening resistance were not obtained.

In Comparative Example 3, the amount of units derived from acrylonitrile and the amount of polymer contained in the eluent-soluble polymer of ≦O to DaO are within the range of the present invention, and has excellent adhesiveness. However, since the amount of 9 in the polymer insoluble in the 90:10 eluent was small, satisfactory blocking resistance and sealing part boil whitening resistance could not be obtained.

Claims (1)

[Claims] (1) a) Unit 8 derived from vinylidene chloride monomer
5 to 93% by weight b) Unit 6 derived from methyl methacrylate monomer
14.5% by weight c) 0.5 to 4% by weight of units derived from monomers copolymerizable with vinylidene chloride having a nitrile group d) Vinylidene chloride other than those described in a), b), and c) above A latex containing a vinylidene chloride copolymer consisting of 0 to 2% by weight of units derived from monomers that can be copolymerized with the eluate, in which tetrahydrofuran and methanol are mixed in a ratio of 60:40 as resin components in the latex. It is characterized by having a polymer (polymer A) soluble in the eluent in a ratio of 4% to 30% by weight and a polymer insoluble in the eluent (polymer B) in a 90:10 ratio of 4% to 60% by weight. Vinylidene chloride copolymer latex. (1) The amount of units derived from the nitrile group-containing monomer contained in Polymer A is 4% by weight or more and 20% by weight or less based on the amount of Polymer A, and the nitrile group-containing unit contained in Polymer B The amount of units derived from the mass is
The vinylidene chloride copolymer latex according to claim 1, wherein the amount is 1% by weight or less based on the amount of polymer B. (3) The vinylidene chloride copolymer latex according to claim 1 or 2, wherein the monomer having a nitrile group is derived from acrylonitrile or methacrylonitrile.