WO2017092146A1

WO2017092146A1 - Cross-linked polyvinyl alcohol film for packaging liquid product and method for preparing same

Info

Publication number: WO2017092146A1
Application number: PCT/CN2016/000040
Authority: WO
Inventors: 费凡·卡琳娜
Original assignee: 知识产权全资有限公司
Priority date: 2015-12-01
Filing date: 2016-01-21
Publication date: 2017-06-08
Also published as: CN105601974B; CN105601974A

Abstract

The present invention relates to a method for producing a UV cross-linked, water soluble polymer or copolymer film comprising hydrolyzed vinyl acetate. If the UV cross-linked, water soluble film comprises a copolymer, then the copolymer comprises the hydrolyzed vinyl acetate and a second monomer. The resulting polyvinyl acetate has a certain degree of hydrolysis in the range of from 50% to 100%, expressed as the percentage of vinyl acetate that is converted to vinyl alcohol units. The second monomer is preferably selected from the group of compounds comprising a carboxylate or sulfonate salt functional group. The present application also relates to a use of the UV cross-linked, water soluble polymer or copolymer in the production of a bag for containing a metered dose of a liquid, such as a laundry liquid or a dishwashing liquid. The UV cross-linked polymer or copolymer has improved resistance to cracking without negatively affecting the solubility of the film.

Description

Crosslinked polyvinyl alcohol film for packaging liquid product and preparation method thereof

Technical field

The present invention relates to an ultraviolet crosslinked polyvinyl alcohol polymer and a copolymer film for packaging liquid products such as laundry liquids and dishwashing liquids, wherein cross-linking does not require the use of a crosslinking agent.

Background technique

Polyvinyl alcohol (PVOH) is a synthetic resin generally obtained by alcoholysis of polyvinyl acetate, that is, hydrolysis or saponification. The fully hydrolyzed PVOH, that is, almost all of the acetic acid is converted into an alcohol, is a polymer having a strong hydrogen bond and high crystallization which can only be dissolved in hot water having a temperature exceeding 60 degrees. If a sufficient amount of acetic acid is present after the hydrolysis of polyvinyl acetate, the polyvinyl alcohol is partially hydrolyzed, and the partially hydrolyzed polyvinyl alcohol has weak hydrogen bonds and low crystallinity, and can be in cold water, ie, the temperature is lower than 50 ° F (10 ° C) of water, dissolved in water. Fully and partially hydrolyzed PVOH is referred to as a PVOH homopolymer, although partially hydrolyzed PVOH is academically a vinyl alcohol and vinyl acetate copolymer.

The term PVOH copolymer is generally used to refer to a polymer from a vinyl ester, typically vinyl acetate, and another monomer. The PVOH copolymer can be called to obtain the properties of the desired film by changing the kind and amount of the copolymer monomer. For example, vinyl acetate and a monocarboxylic acid or a carboxylic acid ester. Similarly, if the hydrolysis of acetic acid in these copolymers is only partial, the resulting polymer is a terpolymer - containing vinyl acetate, vinyl alcohol, and carboxylates - although commonly referred to as It is a copolymer.

It is known that many PVOH copolymers can be dissolved in cold water more rapidly with respect to partially hydrolyzed PVOH homopolymers due to their structure. These copolymers are better suited for the production of packaging films for liquid and powdered products including agrochemicals, household and industrial cleaning chemicals, laundry detergents, water treatments and the like. product.

The above copolymer can be obtained by hydrolysis of a copolymer of vinyl acetate and a vinyl carboxylate monomer, and a copolymer of a vinyl acetate and a vinyl carboxylate monomer (base-catalyzed alcoholysis). In the presence of sufficient base, the acid (including the acid resulting from the ester hydrolysis reaction) is neutralized to form a carboxylate. These PVOH copolymers, as well as films made therefrom, are rapidly soluble in cold water. The carboxylic acid-containing PVOH copolymer obtained from the monocarboxylic acid ethylene monomer and its ester is passed through a vinyl acetate-acrylic acid copolymer, vinyl acetate-crotonic acid, vinyl acetate-methyl acrylate, vinyl acetate-methyl Acrylic acid, vinyl acetate-methyl methacrylate is obtained by hydrolysis, and these compounds all have good solubility in cold water. In fact, a packaging film made from a PVOH copolymer containing a carboxylate is considered to be the fastest film dissolved in cold water.

The largest market for these membranes is laundry detergents and dishwashing liquids. The convenience of using unit doses in these liquid applications has been widely accepted, and the rapid dissolution properties of packaging films are well suited for the use of these products. A PVOH film was placed on the conveyor belt with a groove under the conveyor belt, and the PVOH film was sucked into the groove when a vacuum was used.

The washing liquid is then poured into the groove. A second layer of PVOH film is then placed over the first layer of PVOH film to seal the liquid. The second layer of PVOH film is previously wetted with water or an aqueous solution of PVOH to increase adhesion between the first and second layers of PVOH film. In addition, pressure can also be used to enhance adhesion between the first and second layers of PVOH film. Manufacturers of laundry detergents and dishwasher cleaners have optimized the adhesion of the first and second PVOH films, however, the effectiveness of the bond between the two films is sufficient for the unit dose of liquid contained therein. The compression resistance prevents the seal from being damaged during production and packaging as well as during subsequent storage processes, and there are serious problems. Optimizing the seal between two layers of PVOH film requires the manufacturer to effectively control the seal strength and continue to ensure good solubility of the laundry and dishwasher detergent unit dose products. In addition, the control of the sealing strength of the two-layer PVOH film has only a narrow operating window, and it takes about 3 seconds to join the second film after the groove is filled. Secondly, if new additives are used to enhance the seal between the two films, these additives need to be chemically compatible with essentially all laundry detergents and dishwasher cleaner formulations, as well as most of the businesses used to package these products. Compatible with membranes.

Summary of the invention

A UV crosslinked water soluble PVOH polymer and copolymer film for use in the production of bags for holding unit doses of liquids, such as laundry liquids and dishwashing liquids. Crosslinking is not required for the crosslinking process. The production process is controlled by exposing the film to ultraviolet light. The solubility of the membrane is not adversely affected by UV crosslinking. The bag produced from the film of the present invention has better pressure resistance and is less susceptible to breakage than the water soluble film of the prior art.

In one embodiment, the UV crosslinking is accomplished by light-directed cleavage of peroxodisulfate added prior to the pre-wetting step prior to the second PVOH film being bonded.

In the above examples, the peroxodisulfate (generally referred to as persulfate) is selected from the group consisting of sodium persulfate, potassium persulfate, and amine persulfate. Preferably, ammonium persulfate is used.

In the above embodiment, the persulfate concentration is less than 30%, preferably less than 25%, and particularly preferably between 5% and 20% in the pre-wetting step.

In the above embodiments, the source of the persulfate cracking for light guidance has a peak emission wavelength of less than 300 nm. In a preferred embodiment, the light source used emits light having a single wavelength of 222 nm, which is a KrCl-exiplex lamp.

In the above embodiment, the UV lamp has sufficient energy to cleave persulfate so that the water-soluble PVOH film can be effectively crosslinked within 3 seconds.

In the above examples, the ultraviolet crosslinked and water-soluble film contains itaconic acid copolymerized with vinyl acetate. After hydrolysis, the polyvinyl alcohol contains a degree of hydrolysis of from 98% to 100%, i.e., the percentage of vinyl acetate converted to vinyl alcohol. The second monomer of the UV-crosslinking and water-soluble PVOH film is selected from the group consisting of a vinyl monomer of a carboxylate, an ester thereof and an acid anhydride thereof, a dicarboxylic acid monomer having a polymerizable double bond, an ester thereof and an acid anhydride thereof. And a vinyl sulfonic acid monomer and an alkali metal salt thereof. The degree of hydrolysis of these copolymers varies.

The second monomer of the UV-crosslinking and water-soluble PVOH film is a monocarboxylic acid vinyl monomer, an ester thereof and an acid anhydride thereof, a dicarboxylic acid monomer having a polymerizable double bond, an ester thereof and an acid anhydride thereof, The monomer is vinyl acetate, maleic acid, monomethyl maleate, dimethyl maleate, maleic anhydride, itaconic acid, monomethyl itaconate, dimethyl itaconate And itaconic anhydride. Preferably, the second monomer is itaconic acid.

In other embodiments, the UV crosslinked and water soluble film PVOH second monomer is a vinyl sulfonic acid monomer or an alkali metal salt thereof. In particular, the second monomer is selected from the group consisting of a sulfonic acid monomer and an alkali metal salt thereof, including vinylsulfonic acid, propylenesulfonic acid, ethanedisulfonic acid, 2-acrylamide-1-methylpropanesulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, 2-methylpropanesulfonic acid-2-methylpropanesulfonic acid, and 2-thioethyl acrylate. It is especially preferred that the second monomer in these examples is 2-acrylamido-2-methylpropanesulfonic acid.

In general, the present invention relates to a UV crosslinked and water soluble PVOH polymer or copolymer film comprising vinyl acetate or an adjacent chain of vinyl acetate copolymerized with a second monomer. The direct bonding of the segments results in improved pressure resistance of the film and reduced breakage of the bag.

Another aspect of the invention relates to the production of a package containing a UV crosslinked liquid product comprising a water soluble film comprising a polyvinyl alcohol copolymer.

detailed description

The following examples further describe examples within the scope of the invention. The examples are intended to be illustrative of the invention and not to limit the invention, and many modifications to these examples do not depart from the scope of the invention.

Example 1

This example does not limit the invention, and these examples serve only as an illustration of the essence of the invention.

In the present invention, an ultraviolet cross-linked polyvinyl alcohol film obtained by base-catalyzed alcoholysis of a product obtained by reacting a special monomer in three chemical groups with vinyl acetate, and having a very high presence in the presence of hydrogen ions Good solubility. The copolymer used in the water-soluble film has 1) a carboxylate or 2) a sulfonate functional group.

1. A copolymer having a carboxylate functional group

a special monocarboxylic acid vinyl monomer (the following structural formula (a)) and its ester, acid anhydride, and a specific dicarboxylic acid monomer containing a polymerizable double bond (the following structural formula (b)) and an ester, an acid anhydride It was chosen to be copolymerized with vinyl acetate.

These copolymer base-catalyzed alcoholysis products produced in water-soluble membranes retain carboxylate functional groups in the presence of hydrogen ions due to their low steric hindrance, thereby not forming a six-membered (delta, delta) lactone ring. Examples of selected monomers are vinyl acetate, maleic acid, monomethyl maleate, dimethyl maleate, maleic anhydride, itaconic acid, monomethyl itaconate, itaconic acid II. Methyl ester, and itaconic anhydride.

Structural formulas (c) and (d) are used to show steric hindrance beneficial gamma-lactones and sterically hindered delta-lactones by display and comparison, respectively, since they form the polyvinyl alcohol polymer backbone.

A copolymerized carboxylate-containing PVOH copolymer, for example, a carboxylate unit of acrylic acid-containing acrylic acid is directly connected to a polymer backbone, and thus, in an acidic state, can be stabilized by formation with an adjacent hydroxyl group. Five-membered ring γ-lactone (formula (c) above). In contrast, a polymer derived from vinyl acetate contains a methylene group between the polymer backbone and the carboxylate unit. In this case, only one six-membered delta lactone (structure (d) as above) can be formed, which is not a one-blocking favorable unit. Additional ingredients, such as itaconic acid, dicarboxylic acid, can eventually form gamma-lactones, but other components can only form delta lactones, which remain intact and the solubility of the membranes is preserved.

Preferably, the UV crosslinked PVOH polymer film uses vinyl acetate as a monomer, and the preferred UV crosslinked PVOH copolymer film contains a comonomer selected from the group consisting of copolymerization of itaconic acid and vinyl acetate. a group containing a carboxylate. A preferred UV crosslinking, water soluble film is based on a vinyl alcohol-co-itaconic acid (sodium salt) copolymer. Copolymer synthesis

The vinyl alcohol-co-itaconic acid copolymer was prepared under nitrogen using methanol as a solvent and 2,2'-azobis(2-methylpropionitrile) (AIDBN) as an initiator. The alcoholysis of the copolymer was carried out in the presence of sodium hydroxide in methanol, and the obtained vinyl alcohol-co-itaconic acid (sodium salt) copolymer was round, washed to remove the remaining sodium acetate, and dried. These reactions are known and described, for example, Moritani et. Al (Copolymer Reprint, Japan, 31, 126 (1982)).

2. Copolymer with sulfonate functional group

The specific vinyl sulfonic acid monomer and its basic metal salt (structure (e) below) are selected for copolymerization with vinyl acetate. The base-catalyzed alcoholysis products of these copolymers are used to produce water-soluble membranes which are rapidly soluble vinyl alcohol-sulfonate copolymers.

The sulfonate group can be converted to a sulfonic acid in the presence of hydrogen ions, but the sulfonic acid group still provides excellent membrane solubility in cold water. Examples of the selected sulfonic acid monomer (and/or its basic metal salt) include vinylsulfonic acid, propylenesulfonic acid, ethanedisulfonic acid, 2-acrylamide-1-methylpropanesulfonic acid, 2-propene. Amido-2-methylpropanesulfonic acid, 2-methylallylamino-2-methylpropanesulfonic acid and 2-sulfoethyl acrylate.

Preferred monomers copolymerized with vinyl acetate are selected from monomers containing sulfonate functional groups, including the sodium salt of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), a preferred copolymer incorporated into a water soluble film. It is a sodium salt copolymer of vinyl alcohol-co-AMPS.

Copolymer synthesis

The vinyl alcohol-co-AMPS copolymer was used as a solvent under nitrogen, methanol as a solvent, and 2,2'-azo (isobutyronitrile) (AIBN). The alcoholysis of the copolymer was carried out in the presence of sodium hydroxide in methanol, and the recovered vinyl alcohol-co-AMPS (sodium salt) copolymer was round, and the residual sodium acetate was washed out and dried. These reactions are known and documented, for example, Moritani and Yamauchi (Polymer, 39(3), 553-557 (1998)).

The preferred degree of polymerization of the vinyl alcohol-co-AMPS (sodium salt) copolymer is from 3 to 18 MPa·s (cps) in an aqueous solution having a viscosity of 4% at 20 ° C, including all combinations thereof and ranges thereof. Particularly preferred is 4 to 12 MPa·s.

The preferred degree of integration of the AMPS comonomer in the vinyl alcohol-co-AMPS (sodium salt) copolymer, in mole percent, ranges from 1 to 8 mole%, including all ranges below and combinations thereof. A preferred ratio is 2.5 to 5 mole%.

The preferred degree of hydrolysis of the AMPS comonomer in the vinyl alcohol-co-AMPS (sodium salt) copolymer is expressed as a percentage of the conversion of vinyl acetate units to vinyl alcohol units, ranging from 90% to 99%. A more preferred range is from 94% to 98%.

Water soluble film component additive

The carboxylate- and sulfonate-functional copolymers in the water-soluble film of the present invention are preferably present in an amount of from 40% to 90% by weight, including all ranges below and combinations thereof. Particularly preferred is from 60% to 80% by weight.

The water-soluble film of the present invention contains a plasticizer, a surfactant, a lubricant, a release agent, a filler, a bulking agent, an anti-blocking agent, in addition to a copolymer containing a carboxylate or a sulfonate functional group. Foaming agents, as well as other functional ingredients. Suitable plasticizers include, but are not limited to, glycerin, diglyceride, sorbitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol having a molecular weight of up to 400 MW, new Pentandiol, trimethylolpropane, polyether polyol and ethanolamine.

Preferred plasticizers are glycerin, triethylene glycol, propylene glycol, and trimethylolpropane. The plasticizer to be integrated in the water-soluble film in the present invention is preferably in an amount of from 5% to 30% by weight, particularly preferably in the range of from 12% to 20%.

Suitable surfactants include nonionic, positive examples, negative examples, and dual ion surfactants. Preferably, the surfactant is a nonionic, positive or dual ion surfactant or a combination thereof. Suitable surfactants include, but are not limited to, polyoxyethylene polyoxypropylene glycols, fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, tertiary alkyne alcohols, and alkanolamides (nonionics). , polyoxyethylene amines, quaternary ammonium salts and quaternized polyoxyethylene amines (cations), as well as amine oxides, N-alkyl betaines and sulfonic acid betaines (diionics). Preferred surfactants are fatty alcohol polyoxyethylene ethers, quaternary ammonium salts and amine oxides. The surfactant is preferably present in the water-soluble film in an amount of from 0.01% to 1% by weight, particularly preferably from 0.1% to 0.6% by weight. Suitable lubricants/release agents include, but are not limited to, fatty acids and salts thereof, fatty alcohols, fatty acid esters, fatty amines, fatty amine acetates, and fatty acid amides. Preferred lubricants/release agents are fatty acids, fatty acid salts and fatty amine acetates. The surfactant is preferably present in the water-soluble film in an amount of from 0.02% to 1.5% by weight, particularly preferably from 0.04% to 0.15% by weight.

Suitable fillers/extenders/anti-blocking agents/antifoaming agents include, but are not limited to, starch, modified starch, Crosslinked polyvinylpyrrolidone, crosslinked cellulose, silica, oxidized metal, calcium carbonate, and mica. Preferred materials are starch, modified starch and silica. The preferred filler/extender/anti-blocking/antifoaming agent amount in the present invention is from 0.1% to 25% by weight, and a particularly preferred range is from 1% to 15%. In the absence of starch, it is preferred that the filler/extender/anti-blocking/antifoaming agent be from 1% to 5% by weight.

Suitable antifoaming agents include, but are not limited to, polydimethylsiloxane and mixtures of hydrocarbons. The preferred antifoaming agent weight percentage in the present invention is from 0.001% to 0.5%, and a particularly preferred range is from 0.01% to 0.1%.

The film thickness ranges between 5 and 200 μm, preferably in the range of 20 to 100 μm, and particularly preferably 40 to 85 μm.

UV crosslinking

Conventional crosslinking processes generally involve the use of a crosslinking agent to form a crosslink between two crosslinking units. When two units in two different polymer backbones crosslink each other, an interchain crosslink is obtained. When two units in the same trunk cross-link each other, an inter-chain cross-link is obtained. The crosslinker is at least a bifunctional molecule that forms a covalent bond between two different units of the polymeric backbone upon reaction. The crosslinker itself is integrated into the crosslinked polymer to form part of the crosslink. These intersections are referred to as "indirect cross-linking." These "indirect crosslinks" contain intermediate molecules - the intermediate molecules have different chain lengths - from the crosslinker itself.

There are generally two ways to obtain a crosslinked polymer. The first method is cross-linking in situ in the polymerization. This crosslinking can be accomplished simply by adding a percentage of the crosslinker, the dimer, to the polymer. A conventional crosslinking agent is, for example, methylenebisacrylamide having the formula (CH ₂ =CHCONH) ₂ CH ₂ . Methylene bis acrylamide is particularly suitable for indirect crosslinking between two units derived from acrylamide monomers. Other conventional crosslinking agents are, for example, di(meth)acrylate, N-(1-hydroxy-2,2-dimethoxyethyl)acrylamide, ethylene glycol dimethacrylate, ethylene glycol. Diacrylate, allyl methacrylate, 1,1,1-trimethylolpropane triacrylate, triallylamine, and the like.

The second method is to carry out a crosslinking reaction after the polymer reactive group derivatization reaction. For example, in the presence of an acidic group, such as poly(acrylic acid), a diester bridge can be formed by a diol crosslinker or a diamide bridge and by a bisamine crosslinker. If a hydroxyl group is present in the polymer backbone, a dicarboxylic acid crosslinker can be used to form the diester bridge.

Both methods create a large space between individual polymer chains. Ester, ether or amide bridges are generally easier to cleave by hydrolysis and are therefore less stable, especially in aqueous solutions, such as liquid laundry liquids or liquid washing liquids. The crosslinked polymer backbone uses a crosslinking agent to improve polymer properties, for example, its water solubility, molecular weight, glass phase transition Temperature, consistency, solubility properties and/or porosity. Moreover, these crosslinking processes generally alter the elastic properties of the polymer polymer. In general, a high degree of crosslinking increases the elasticity of the polymer and improves the pressure resistance and break resistance of the polymer. However, excessive cross-linking can make the polymer brittle.

Other crosslinking methods are known in various fields, for example, processes for producing superabsorbent polymers containing polymer segments that are directly linked to each other by covalent bonds. The superabsorbent materials are commonly used in watering products such as diapers, training pants, adult urinary incontinence products, and feminine hygiene products to increase the water absorption of these products while reducing their volume. See EP 1 568 385 A1 for details.

According to a first aspect, the present invention relates to an ultraviolet crosslinked and water soluble PVOH film comprising a polymerized unit (A), wherein unit (A), in its uncrosslinked form, contains at least one carbon atom, The carbon atom contains an alpha hydrogen relative to R ₃ and has the following chemical formula I

Wherein R _{3 is} selected from the group consisting of a hydroxyl group, an acetic acid, a carboxyl derivative, and a sulfonate.

Wherein R ₁ , R ₂ , R ₄ , and R _{5 are the} same or different and are selected from the group consisting of hydrogen, acetic acid, sulfonic acid or a derivative thereof, a sulfonate or a derivative thereof, a carboxylic acid or a derivative thereof, a carboxylate Or a derivative thereof, wherein m, o, and n are independent of each other, m ≥ 0, o ≥ 0, and n ≥ 1, and the direct covalent bond between the α-carbon and the two different units (A) is relatively The alpha-carbon formation at R3 wherein the bond does not contain an intermediate molecule.

Another aspect of the invention relates to the production of a unit dose laundry or wash liquor packaging unit using the previously described UV crosslinked and water soluble PVOH film.

Another aspect of the invention relates to the production of the UV crosslinked and water soluble PVOH film previously described.

The "unit (A)" represents a repeating unit of one monomer constituting the polymer, and contains at least one carbon atom and a substitute thereof, and is polymerized with other units to form a polymer chain. The unit is derived from a monomer molecule (A)- or a monomer (A).

"R3" represents an electron withdrawing group which can cleave the α-hydrogen bond.

"Photoreactant" means a reactant that can be activated by ultraviolet light to produce a pair of first free radicals. The free radicals absorb hydrogen radicals at the alpha position relative to the electron withdrawing group in the saturated polymer backbone.

"Direct covalent bond" means that two different units (A) of the a-carbon atoms are linked to each other by a covalent bond which is formed by a break between carbon-hydrogen bonds with respect to R3, said covalent bond being free of intermediate Molecule, where "minutes """ refers to at least one atom. The "direct covalent bond" is different in the present invention from the covalent bond formed during the polymerization of two adjacent units in one polymeric chain. Conversely, the present invention The "direct covalent bond" is formed in the second step (crosslinking step) after polymer formation (polymerization step).

The "polymer" in the present invention means a homopolymer formed by polymerization of one monomer (A) and a copolymer formed by polymerization of at least two monomers, monomer (A) and monomer (B). The copolymer may contain more than two comonomers. The "polymer" of the present invention is also a mixture of at least one homopolymer and at least one other homopolymer or copolymer, or a mixture of at least two copolymers. A mixture of polymers is characterized by a glass transition temperature TgB that is approximately equal to a weighted average of the glass transition temperatures of its constituents. For example, the glass transition temperature TgA,B of a polymer mixture composed of 50% homopolymer (A) and 50% homopolymer (B) is approximately equal to (TgA + TgB)/2.

The "weighted average" and "percent by weight" refer to the percentage of active ingredient, rather than the percentage of the original material containing the active ingredient and other unspecified ingredients. All percentages and ratios refer to weight unless otherwise stated.

The inventors have surprisingly found that PVOH polymers and copolymers can be effectively and efficiently UV-crosslinked to enhance pressure resistance, thereby increasing the resistance to breakage of laundry liquids and washing liquids without affecting their water solubility. Here, "effectively" means that UV crosslinking can be accomplished at the interface of the first and second PVOH polymer and copolymer films. "Efficiently" means that the UV crosslinking is completed within an irradiation time of less than 3 seconds. Without being bound by any theory, the cross-linking techniques described herein may result in a polymer having a high crosslink density at the interface of two PVOH films. In fact, the free hydrogen present in the polymer saturated carbon backbone reacts, not only depends on the "functional group" in the polymer, the crosslink density obtained is higher, and the obtained direct covalent bond can be more evenly distributed. In polymers or copolymers. In addition, free radicals are generated by ultraviolet irradiation of the photoreaction mixture and the PVOH membrane, so the reaction is "kinetically controlled" without "thermodynamic control", reflecting the traditional cross-linking reaction in temperature and pressure in conventional cross-linking.

The inventors have also surprisingly found that the water solubility of UV crosslinked PVOH polymers and copolymers is not negatively affected. Without being bound by any theory, these improved properties are believed to be due to the high crosslink density and a more uniform distribution of direct covalent bonds in the newly formed crosslinked polymer. In conventional cross-linking, the crosslink density is high and low, and the high cross-link density region negatively affects the solubility.

The bag made of the UV crosslinked PVOH film uses a cross-linking process which is different from the conventional cross-linking process in which an indirect covalent bond is formed using a cross-linking agent. The cross-linking process of the present invention includes the step of forming a direct covalent bond between the α-carbons of two different units (A) by cleavage of the α-hydrogen bond. The direct covalent bond and the indirect covalent bond are not The same thing is that it does not contain intermediate molecules.

The direct covalent bond can be formed between two units (A) in one polychain, which is an in-chain direct covalent bond. The direct covalent bond can also be formed between two different chain units (A), which are direct covalent bonds between the chains.

Preferably, the direct covalent bond is obtained by exposing the polymer to ultraviolet irradiation, using ultraviolet rays having a wavelength of 170 nm to 400 nm, an irradiation time of 0.001 to 20 seconds, and in the presence of a photoreactive substance, The ratio of the photoreactive substance to the unit (A) is from 0.01 to 1, and no crosslinking agent is used. It is especially preferred that the direct covalent bond is carried out at a temperature of from 0 ° C to 95 ° C.

Alternatively, the direct covalent bond is carried out in the presence of an activated photoreactant, the ratio of the photoreactant to unit (A) is from 0.01 to 1, and no crosslinker is used. Preferably, the direct covalent bond is between 20 ° C and 70 ° C. The photoreactant was activated by exposure to ultraviolet light using a wavelength of 170 nm for a period of 0.001 to 20 seconds.

The "photoreactant" refers to a substance capable of forming a radical under irradiation of light, particularly under irradiation of ultraviolet rays. The inventors have surprisingly found that in order to form a direct covalent bond, it is necessary to use a photoreactant which is in an activated state and which has a certain ratio by weight to unit (A). Activation of the photoreactant is achieved by irradiating it with ultraviolet light having a wavelength between 170 nm and 400 nm for 0.01 to 20 seconds. Activation of the photoreactant and formation of direct covalent bonds can occur simultaneously. Alternatively, activation of the photoreactant occurs prior to the formation of a direct covalent bond. The use of ultraviolet radiation having a wavelength between 170 nm and 400 nm is necessary because the preferred photoreactant absorbs only ultraviolet light. A ratio between the photoreactant and unit (A) of between 0.01 and 1 is also necessary to form a direct covalent bond. When the ratio is less than 0.01, no direct covalent bond is expected to occur. The range is between 0.02 and 0.4, particularly preferably between 0.03 and 0.3.

The photoreactant can be a persulphate. Preferably, the persulphate is selected from the group consisting of sodium persulfate, potassium persulfate, ammonium persulfate or mixtures thereof. Persulfate is preferably used because of its ease of use, high solubility in water, and homogenization when irradiated with ultraviolet light in water while forming two identical negative ion radicals which are in close proximity to each other.

0.01% to 100% of the units (A) can be crosslinked by direct covalent bonds. Preferably, 0.1% to 50% of the units (A) are crosslinked. Particularly preferred, 1% to 5% of the units (A) are crosslinked. When only a part of the unit (A) is crosslinked by a direct covalent bond, the ultraviolet crosslinked PVOH film contains the unit (A) in a crosslinked form and the unit (A) in a non-crosslinked form. The degree of crosslinking, such as the ratio of the crosslinking unit (A), results in a difference in pressure resistance and water solubility.

According to the present invention, any PVOH polymer or copolymer film used to package the laundry liquid and the washing liquid is suitable for direct direct covalent bonding for UV crosslinking.

The inventors have surprisingly found that UV crosslinked PVOH polymer and copolymer films have improved pressure resistance at the first and second film boundaries. For example, PVOH polymers and copolymers crosslinked by direct covalent bonds have better pressure resistance at the seal between the two PVOH films, while maintaining good water solubility. By using UV crosslinked PVOH polymer and copolymer films as packaging materials for laundry detergents and washing liquids, the possibility of product contamination can be significantly reduced, thereby increasing customer satisfaction.

The invention further relates to the use of UV crosslinked PVOH polymer and copolymer films as packaging materials for laundry liquors and wash liquors. The inventors have surprisingly found that the use of such UV-crosslinked PVOH films provides better sealing than PVOH films that currently do not contain direct covalent bonds on the market.

The present invention relates to the manufacture of the above UV crosslinked PVOH polymer and copolymer film, the method comprising:

(a) providing a first PVOH film comprising from 1% to 100% of polymerized units (A),

(b) providing a second PVOH film containing from 1% to 100% of the polymerized unit (A) and being wetted by an aqueous solution containing a photoreactant,

(c) forming a direct covalent bond between the α-carbons of two different units (A) by cleavage with respect to the α-hydrogen bond of R3, the covalent bond does not contain an intermediate molecule,

(d) combining the first and second PVOH films by applying pressure to at least one of the PVOH films.

Step (c) is carried out by exposing the polymer to ultraviolet irradiation at a wavelength of 170 nm to 400 nm for 0.001 to 20 seconds, and containing a photoreactant, the ratio of the photoreactive substance to the unit (A) being 0.01 to 1, and does not contain any The crosslinking agent preferably has a temperature of from 0 ° C to 95 ° C.

Alternatively, step (b) contains several substeps, (b1) providing an aqueous solution of the photoreactant, and (b2) is activated by exposing the photoreactant to ultraviolet radiation having a wavelength of from 170 nm to 400 nm for 0.001 to 20 seconds, ( B3) The photoreactant is used on the PVOH film, the ratio of the photoreactant to unit (A) being from 0.01 to 1.

Experimental information

In the present invention, the SAP particles are exposed to ultraviolet light. The ultraviolet region of the electromagnetic spectrum is defined between wavelengths of 100 nm to 400 nm and is divided into the following regions: UV-A (315 nm - 400 nm), UV-B (280 nm - 315 nm), UV-C (200 nm - 280 nm), and vacuum. Ultraviolet field UV (VUV) (100nm-200nm).

For VUV, it is preferred to use a pulsed or continuous xenon (Xe2-) source of excited atomic radiation. The excimer lamp emits quasi-monochromatic incoherent radiation relative to known excimer lasers. Non-coherent excimer radiation is carried out by a special gas such as microwave discharge or dielectric barrier discharge (DBD, silent discharge). Preferred Xe2-placement Shot in a special region of VUV, 160 nm to 200 nm, showing a wider band with a peak value width (FWHM) of 14 nm at 172 nm. The VUV spectrum is preferably used in the present invention at a wavelength of from 160 nm to 200 nm, with a peak having a peak at 172 nm.

Xe2- a pulsed excimer radiation source suitable for laboratory studies tradename for ^{Xeradex TM, (Osram China Lightning Ltd.} , Shanghai, China), the electric power of 20W to 100W. However, if the method of the present invention is used to crosslink a PVOH film, the film used is a normal industrial usage, and the radiation power may be 10 kW or higher.

Sources of sustained Xe2-excito atomic radiation with power up to 10 kW are available from Heraeus Noblelight (Shenyang) Ltd, Shanghai, China, and smaller sources are available from Ushio Shanghai Inc., China.

UV radiation in the UV-A, UV-B or UV-C region, depending on the nature, concentration and presence or absence of the photoinitiator, can be irradiated with mercury arc or metal halide. The choice of source depends on the absorption spectrum of the photoreactant and the geometry of the device for increasing the sealing of the PVOH film by crosslinking. The UV-C region proved to be the most preferred region of the invention in combination with the photoreactants previously described. The source of radiation can be cooled with a gas or it can contain a cooling jacket.

When the wavelength of the ultraviolet radiation is from 200 nm to 400 nm, it is recommended to carry out the invention under usual air to save money. Without being limited to any theory, the use of general air can improve the effect of crosslinking because oxygen, as a diradical, can participate in the reaction by forming intermediate peroxy radicals upon irradiation. Thus, the increased number of free radicals available can help form the carbon-centered free radical molecules of the polymer backbone in the PVOH film. When the wavelength of ultraviolet irradiation is between 200 nm and 400 nm, the humidity is not important because water molecules do not absorb in this area. experiment method:

The test method consisted of adhering two PVOH films to each other and exposing them to ultraviolet light to measure the sealing strength of the newly formed double-layer PVOH film. Contains the following steps:

1. The PVOH roll film was cut into 5 cm (length) x 5 cm (width) = 25 cm ² (area) samples and equilibrated for 12 hours at 65% relative humidity at 25 °C. The weight of each sample after equilibration was recorded.

2. An aqueous solution having a certain concentration of photoreactive material is used on the surface of the first PVOH film, having an area of 2.5 cm (length) x 5 cm (width) = 12.5 cm ² (area), through a commercially available spray gun, in a PVOH film. Spray at a distance of 10cm. The other half of the first PVOH film (12.5 cm ² surface area) remained dry. The weight of the treated first PVOH film after recording the aqueous solution of the photoreactant was recorded.

3. A second PVOH film is placed over the first PVOH film to cover the first film.

4. 12.5 cm ^{2 of the} second PVOH film sample was covered by the first PVOH film. The adhered first and second PVOH films were irradiated for 1 minute at a distance of 10 cm using an Osram Puritec HNS UV lamp (Type L 95W2G11) having a general UV-C radiation power of 27 W.

5. Thereafter, the lamp was turned off (or capped) using a weight of 500 g for 1 minute on a total surface area of 25 cm ² of the bonded PVOH film.

6. After that, the weight was removed and the sample was equilibrated for 1 hour at 65% relative humidity and 25 °C. The weight of the composite PVOH film was recorded.

7. After balance and weighing, the sample was placed on an Instron electronic strength tester, untreated (photoreactant and UV-C light) 5 cm up and down in the corresponding pliers, breaking strength through ASTM D5043 The method is measured and recorded [1b].

8. The effect of the measured photoreactant concentration on the improved rupture strength was measured in 10 PVOH pressed films (20 PVOH films), averaged, and expressed as the result relative to the film pressed only with water. .

China Haining Shenjia New Material film Co., Ltd., a PVOH film of a quality grade of "SD" was used, and the results were as follows.

Table 1

The effect of UV-C exposure time was investigated and the test in Table 1 was continued at an irradiation time of 5 minutes (step 4 in the method).

Table 2

Claims

A crosslinked polyvinyl alcohol film for packaging a liquid product, comprising a polymer or copolymer comprising a hydrolyzed vinyl acetate unit and a second monomer unit, characterized in that said vinyl acetate 50% to 100% of the unit is converted to vinyl alcohol, and the second monomer unit is selected from the group consisting of vinyl groups containing a carboxylic acid group or a sulfonic acid group;

The liquid product is a liquid detergent and the polymer or copolymer film is crosslinked by ultraviolet light.
The crosslinked polyvinyl alcohol film according to claim 1, wherein the second monomer in the second monomer unit is selected from the group consisting of vinyl acetate, maleic acid, monomethyl maleate, and Malay. Dimethyl methacrylate, maleic anhydride, itaconic acid, monomethyl itaconate, dimethyl itaconate, and itaconic anhydride.
The crosslinked polyvinyl alcohol film according to claim 2, wherein the second monomer is polymerized in a ratio of from 1.5 mole% to 11 mole%.
The crosslinked polyvinyl alcohol film according to claim 2 or 3, wherein the maleate is integrated in a ratio of from 2.5 mole% to 8.5 mole%.
The crosslinked polyvinyl alcohol film according to any one of claims 1 to 3, wherein the crosslinking is carried out at a wavelength of from 170 nm to 400 nm for from 0.001 to 20 seconds.
The crosslinked polyvinyl alcohol film according to any one of claims 1 to 3, wherein the crosslinking is carried out at a wavelength of from 200 nm to 300 nm for from 0.001 to 10 seconds.
The crosslinked polyvinyl alcohol film according to any one of claims 1 to 3, wherein the crosslinking is carried out without the addition of other crosslinking agents, directly by covalent bonds in the presence of a photoreactive material.
The crosslinked polyvinyl alcohol film according to claim 7, wherein the photoreactant is a persulphate selected from the group consisting of sodium persulfate, potassium persulfate, ammonium persulfate or a mixture thereof.
A method for preparing a UV crosslinked PVOH film, comprising the steps of:

(1) providing a first PVOH film;

(2) providing a second PVOH film;

(3) soaking the PVOH membranes of steps (1) and (2) with an aqueous solution of persulfate;

(4) irradiating the PVOH film wetted in the step (3) with ultraviolet rays having a wavelength of 170 nm to 400 nm;

(5) Combining the first and second PVOH films to form a bag containing a liquid detergent.
The preparation method according to claim 9, wherein the step (5) is carried out under pressure.
The preparation method according to claim 9 or 10, wherein the step (5) is carried out before the step (4).