DE102010002856A1 - Film comprising plasticizer useful for producing laminated glazing, wind screens or photovoltaic modules comprises polyvinyl acetal with residual polyvinyl alcohol content and at least one isosorbide diester - Google Patents

Abstract

Film comprising plasticizer comprises 60-90% polyvinyl acetal with a residual polyvinyl alcohol content of less than 22 wt.% and 10-40 wt.% of at least one isosorbide diester (I) as a plasticizer. Film comprising plasticizer comprises 60-90% polyvinyl acetal with a residual polyvinyl alcohol content of less than 22 wt.% and 10-40 wt.% of at least one isosorbide diester of formula (I) as a plasticizer. R1, R2, R3, R5, R6, R7, R8, R10 : H, 1-5C alkyl; and R4, R9 : ester with 1-20C aliphatic, aromatic or cyclic acid portion. [Image].

Description

Technical area

The invention relates to a suitable as an intermediate layer in laminated safety glasses plasticized film based on partially acetalized polyvinyl alcohols using Isosorbiddiestern as plasticizer or the use of Isosorbiddiestern as a plasticizer for such films.

State of the art

Laminated safety glass generally consists of two glass panes and an intermediate foil connecting the glass panes. The film material used is predominantly plasticizer-containing partially acetalized polyvinyl alcohol (polyvinyl acetal), in particular polyvinyl butyral (PVB). Laminated safety glass (VSG) are used for example as windscreens or side glazing in the automotive sector and as safety glazing in the construction sector.

Aliphatic diesters of tri- or tetraethylene glycol are now established as plasticizers for such PVB films. Particularly often used as plasticizers 3G7, 3G8 or 4G7, wherein the first digit denotes the number of ethylene glycol units and the last digit the number of carbon atoms in the carboxylic acid portion of the compound. Thus, 3G8 is triethylene glycol bis (2-ethylhexanoate), ie a compound of formula C ₄ H ₉ CH (CH ₂ CH ₃ ) CO (OCH ₂ CH ₂ ) ₃ O ₂ CCH (CH ₂ CH ₃ ) C ₄ H _{9 .} Like other plasticizers previously used for PVB film, these esters are based on petrochemical primary products.

In principle, the plasticizers used for partially acetalized polyvinyl alcohols are preferably compounds which ensure high transparency, low moisture absorption, good adhesion to the glass and sufficient low-temperature flexibility of the film in a VSG interlayer film. Furthermore, these compounds must have sufficient compatibility with the partially acetalized polyvinyl alcohol, d. H. in a sufficient amount without sweating out again be miscible with this.

With the continued scarcity or increase in price of mineral oil, the availability of such plasticizers is deteriorating, so that the use of plasticizers based on alternative - renewable - raw materials makes sense. So be in WO 99/45060 and WO 2008/095571 Diester of isosorbide (CAS: 652-67-5) is proposed as a plasticizer, inter alia, for PVC and polyvinyl acetal adhesives (eg polyvinyl butyral, PVB). Isosorbide is a bicyclic diol which can be obtained via the intermediates glucose and sorbitol from the renewable raw material starch.

Films for laminated safety glass must have a certain mechanical strength, high transparency and sufficient UV stability, low-temperature flexibility and low moisture absorption, in addition to a bonding behavior adapted to the respective use of glass. These properties are set by the plasticizer properties and the chemical composition of the polyvinyl acetal used.

WO 99/45060 and WO 2 008/095571 concern adhesives and not foils for laminated safety glass. Therefore, no information can be found from these publications whether the described diesters of isosorbide are suitable as plasticizers for PVB in these applications. Thus, no information is given on the type and composition of the polyvinyl acetal used or the amount of plasticizer required for an interlayer film for laminated glass.

task

There has been a need to formulate a PVB film using a plasticizer based on renewable raw materials, which is well-tolerated with partially acetalized polyvinyl alcohols of sufficiently high degree of acetalization and gives the film sufficient cold flexibility and edge stability.

Presentation of the invention

It has been found that diesters of isosorbide can be used as plasticizers for polyvinyl acetals for the production of interlayer films for laminated glass and these films have good transparency, sufficient edge stability and good adhesion to glass surfaces.

Tests show that not every combination of isosorbide diol and carboxylic or fatty acids as ester acid with polyvinyl acetals of different polyvinyl alcohol contents leads to useful PVB films for laminated safety glass.

In particular when short-chain ester acids are used, the plasticizers obtained are so volatile that they lead directly to several product disadvantages: u. a. It has been found that when using ester acids having an average C-atom number less than 5 (C5), the edge stability of the laminates produced with such films is poor due to the high volatility. Furthermore, the high volatility leads to dangerous outgassing of plasticizer in the autoclave or condensation in the vacuum laminators also used for the processing of PVB films.

The average chain length of the ester acids used must also not be too high, since otherwise, depending on the polyvinyl alcohol content of the polyvinyl acetal used, incompatibility also results with adverse effects on the product quality. Another undesirable effect of using ester plasticizers having too large a chain length in the ester acid moiety is insufficient cold flexibility, which degrades the safety properties of the laminated glass sheet produced by the film at low temperatures.

wobei R₁, R₂, R₃, R₅, R₆, R₇, R₈, R₁₀ jeweils gleich oder unterschiedlich für H, Alkylkette mit 1 bis 5 Kohlenstoffatomen und R₄ und R₉ jeweils gleich oder unterschiedlich für eine Estergruppe mit 1 bis 20 Kohlenstoffatomen im aliphatischen, aromatischen oder cyclischen Säureteil, bevorzugt in der Form OCOR₄ bzw. OCOR₉ stehen.The present invention therefore relates to a plasticizer-containing film containing 60 to 90% polyvinyl acetal having a residual polyvinyl alcohol content of less than 22 wt .-% and 10 to 40 wt .-% of at least one Isosorbiddiester according to the general formula 1 as a plasticizer

wherein R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ , R ₈ , R _{10 are} each the same or different for H, alkyl chain having 1 to 5 carbon atoms and R ₄ and R ₉ are the same or different for an ester group with 1 to 20 carbon atoms in the aliphatic, aromatic or cyclic acid moiety, preferably in the form of OCOR ₄ or OCOR ₉ .

eingesetzt, wobei R₁₁ und R₁₂ jeweils gleich oder unterschiedlich für aliphatische Reste mit 5 bis 11 Kohlenstoffatomen stehen.Preference is given to isosorbide diesters according to formula 2

used, wherein R ₁₁ and R ₁₂ are the same or different for aliphatic radicals having 5 to 11 carbon atoms.

Besides the chain length, the structure of the ester acid is important because of its influence on the hydrolytic stability of the plasticizer. When using linear carboxylic acids, the hydrolytic stability of Isosorbiddiester is not sufficient. It is foreseeable that such plasticizers are easily split by water contained in or penetrating into the PVB film, which adversely affects the adhesion to the glass and favors delamination by the loss of the resulting low molecular weight cleavage products.

As ester acids for the radicals R ₄ and R ₉ or R ₁₁ and R ₁₂ are in particular those having 5 to 11 carbon atoms and more preferably those having 6, 8, or 9 carbon atoms used. These acids can be branched or unbranched, with the use of branched ester acids giving the PVB film better chemical stability. In particular, ester radicals with branching such as 2-ethylhexanoic acid, 2-ethylbutanoic acid, iso-nonanoic acid, iso-decanoic acid, etc. are used for the radicals R ₄ and R ₉ or R ₁₁ and R ₁₂ . Isosorbide diesters of this type are z. B. from the company Roquette available.

The isosorbide diester plasticizers used according to the invention can be used in combination with at least one other plasticizer which is also suitable as an auxiliary plasticizer in a proportion of from 1 to 40% by weight, based on the total amount of plasticizer.

The films preferably have a total plasticizer content d. H. the proportion of all plasticizers in the film in the range of 10-45 wt .-%, 14-36 wt .-%, 16-32 wt .-%, 18-30 wt .-%, in particular 22-28 wt .-% on. The proportion of isosorbide diester plasticizers used according to the invention can be more than 10%, more than 20%, more than 30%, more than 40%, more than 50%, more than 60%, more than 70%, more than 80%, or more than 90% ,

• – Ester von mehrwertigen aliphatischen oder aromatischen Säuren, z. B. Dialkyladipate wie Dihexyladipat, Dioctyladipat, Hexylcyclohexyladipat, Mischungen aus Heptyl- und Nonyladipaten, Diisononyladipat, Heptylnonyladipat sowie Ester der Adipinsäure mit cycloaliphatischen oder Etherbindungen enthaltenden Esteralkoholen, Dialkylsebazate wie Dibutylsebazat sowie Ester der Sebazinsäure mit cycloaliphatischen oder Etherbindungen enthaltenden Esteralkoholen, Estern der Phthalsäure wie Butylbenzylphthalat oder Bis-2-butoxyethylphthalat, Estern der Cyclohexandicarbonsäure wie deren Di-isononylester (DINCH) oder Di-isononylester der Adipinsäure (DINA)
• – Ester oder Ether von mehrwertigen aliphatischen oder aromatischen Alkoholen oder Oligoetherglykolen mit einem oder mehreren unverzweigten oder verzweigten aliphatischen oder aromatischen Substituenten, wie z. B. Estern von Di-, Tri- oder Tetraglykolen mit linearen oder verzweigten aliphatischen oder cycloaliphatischen Carbonsäuren; Als Beispiele für letztere Gruppe können dienen Diethylenglykol-bis-(2-ethylhexanoat), Triethylenglykol-bis-(2-ethylhexanoat), Triethylenglykol-bis-(2-ethylbutanoat), Tetraethylenglykol-bis-n-heptanoat, Triethylenglykol-bis-n-heptanoat, Triethylenglykol-bis-n-hexanoat, Tetraethylenglykoldimethylether und/oder Dipropylenglykolbenzoat.
• – Sog. Zusatzweichmacher sind zum Beispiel Di-(2-butoxyethyl)-adipat (DBEA), Di-(2-butoxyethyl)-sebacat (DBES), Di-(2-butoxyethyl)-azelat, Di-(2-butoxyethyl)-glutarat. Di-(2-butoxyethoxyethyl)-adipat (DBEEA), Di-(2-butoxyethoxyethyl)-sebacat (DBEES), Di-(2-butoxyethoxyethyl)-azelat, Di-(2-butoxyethoxyethyl)-glutarat, Di-(2-hexoxyethyl)-adipat, Di-(2-hexoxyethyl)-sebacat, Di-(2-hexoxyethyl)-azelat, Di-(2-hexoxyethyl)-glutarat, Di-(2-hexoxyethoxyethyl)-adipat, Di-(2-hexoxyethoxyethyl)-sebacat, Di-(2-hexoxyethoxyethyl)-azelat, Di-(2-hexoxyethoxyethyl)-glutarat, Di-(2-butoxyethyl)-phthalat und/oder Di-(2-butoxyethoxyethyl)-phthalat.

In principle, the films may comprise plasticizer mixtures of the said isosorbide diester plasticizers with at least one of the following plasticizers known for PVB film:

• Esters of polyhydric aliphatic or aromatic acids, e.g. As Dialkyladipate as Dihexyladipat, Dioctyladipat, Hexylcyclohexyladipat, mixtures of heptyl and nonyl adipates, Diisononyladipat, Heptylnonyladipat and esters of adipic acid with cycloaliphatic or ether-containing ester alcohols, dialkyl sebacates such as dibutyl sebacate and esters of sebacic acid with cycloaliphatic or ether bonds containing ester alcohols, esters of phthalic acid such as butyl benzyl phthalate or bis-2-butoxyethyl phthalate, esters of cyclohexanedicarboxylic acid such as its di-isononyl ester (DINCH) or di-isononyl ester of adipic acid (DINA)
• - Esters or ethers of polyhydric aliphatic or aromatic alcohols or Oligoetherglykolen with one or more unbranched or branched aliphatic or aromatic substituents, such as. B. esters of di-, tri- or tetraglycols with linear or branched aliphatic or cycloaliphatic carboxylic acids; As examples of the latter group may be used diethylene glycol bis (2-ethylhexanoate), triethylene glycol bis (2-ethylhexanoate), triethylene glycol bis (2-ethylbutanoate), tetraethylene glycol bis-n-heptanoate, triethylene glycol bis-n heptanoate, triethylene glycol bis-n-hexanoate, tetraethylene glycol dimethyl ether and / or dipropylene glycol zoate.
• - So-called. Additional plasticizers are, for example, di (2-butoxyethyl) adipate (DBEA), di (2-butoxyethyl) sebacate (DBES), di (2-butoxyethyl) azelate, di (2-butoxyethyl) glutarate. Di (2-butoxyethoxyethyl) adipate (DBEEA), di (2-butoxyethoxyethyl) sebacate (DBEES), di (2-butoxyethoxyethyl) azelate, di (2-butoxyethoxyethyl) glutarate, di (2 hexoxyethyl) adipate, di (2-hexoxyethyl) sebacate, di (2-hexoxyethyl) azelate, di (2-hexoxyethyl) glutarate, di (2-hexoxyethoxyethyl) adipate, di (2 hexoxyethoxyethyl) sebacate, di (2-hexoxyethoxyethyl) azelate, di (2-hexoxyethoxyethyl) glutarate, di (2-butoxyethyl) phthalate and / or di (2-butoxyethoxyethyl) phthalate.

In order not to worsen the moisture resistance of the films unnecessarily by using a too polar plasticizer in the mixture, especially plasticizers of low polarity can be combined with the isosorbide diester plasticizers used according to the invention. Plasticizers having a polarity of less than or equal to 9.4 calculated according to the formula 100 × (number of O atoms) / (number of C atoms + number of H atoms) are considered as plasticizers of low polarity. As plasticizers of low polarity, preference is given to using dialkyl adipates having an alkyl radical having more than 6 carbon atoms and oligoglycolic acid esters having a carboxylic acid radical having more than 7 carbon atoms. Particularly suitable are the following compounds: Surname abbreviation 100 × O / (C + H) Di-2-ethylhexyl (DOS) 5.3 1,2-cyclohexane-di-isononyl (DINCH) 5.4 Di-2-ethylhexyl (DOA) 6.3 Di-2-ethylhexyl phthalate (DOP) 6.5 dihexyladipate (DHA) 7.7 dibutyl (DBS) 7.7 Triethylene glycol-bis-2-propylhexanoat 8.6 Triethylene glycol-bis-i-nonanoate 8.6 Di-2-butoxyethylsebacat (DBES) 9.4 Triethylene glycol-bis-2-ethylhexanoate (3G8) 9.4

In addition, films according to the invention may comprise further additives known to the person skilled in the art, such as residual amounts of water, UV absorbers, antioxidants, adhesion regulators, optical brighteners, stabilizers, Colorants, processing aids, organic or inorganic nanoparticles, fumed silica and / or surfactants.

By using said plasticizers or plasticizer combinations, it is possible to produce films with a particularly low release of plasticizer, which brings with it the advantage of reduced odor nuisance or probability of occurrence of plasticizer aerosols during further processing and offers the advantage of increased longevity in the finished laminated safety glass.

Preferably, the plasticizer delivery of the films of the present invention (as hereinafter defined) is less than 4 weight percent, preferably 3 weight percent, more preferably less than 2 weight percent and most preferably less than 1 weight percent, respectively based on the total film.

Preference is given to using a partially acetalized or partially butyralized polyvinyl alcohol (polyvinyl butyral) having a polyvinyl acetal content (degree of acetalization) 77% by weight, 78, 79, 80, preferably 81, more preferably 82, in particular 83% by weight, since these are partially acetalized Polyvinyl alcohols have sufficiently low softening temperatures and polarities and with the isosorbide diester plasticizers compatible formulations with good low-temperature flexibility. However, an acetalization degree of 87% by weight should not be exceeded, since then the mechanical properties of the film are sufficient for most applications. In particularly preferred variants of the invention, the degree of acetalization at about 1 wt .-% residual acetate at 77-87 wt .-%, 79-86 wt .-%, 80-85 wt .-% and 81-84 wt .-% , At higher residual acetate contents (above 1% by weight), the stated numerical values for the degree of acetalysis are correspondingly reduced.

The sum of degree of acetalation and residual acetate may be as the missing part of 100 from the according to ASTM D 1396 certain polyvinyl alcohol content, ie the proportion of free hydroxyl groups of the polyvinyl acetal are calculated. The degree of acetalation can also be directly determined by high-resolution NMR spectroscopy.

In order for the films according to the invention to have sufficient cold flexibility coupled with sufficient mechanical strength at elevated temperature, the polyvinyl acetals usable for the invention generally have softening temperatures (Tg) of less than or equal to 77 ° C., preferably in the range of 64-76 ° C., preferably 65 -75 ° C, more preferably 66-74 ° C and especially in the range 67-73 ° C on.

For the preparation of polyvinyl acetal polyvinyl alcohol is dissolved in water and acetalized with an aldehyde such as butyraldehyde with the addition of an acid catalyst. The precipitated polyvinyl acetal is separated, washed neutral, optionally suspended in an alkaline aqueous medium, then washed neutral again and dried.

The polyvinyl alcohol content of the polyvinyl acetal can be adjusted by the amount of aldehyde used in the acetalization. It is also possible to carry out the acetalization with other or several aldehydes having 2-10 carbon atoms (eg valeraldehyde).

The films based on plasticized polyvinyl acetal preferably contain uncrosslinked polyvinyl butyral (PVB), which is obtained by acetalization of polyvinyl alcohol with butyraldehyde.

The use of crosslinked polyvinyl acetals, especially crosslinked polyvinyl butyral (PVB) is also possible. Suitable crosslinked polyvinyl acetals are, for. In EP 1527107 B1 and WO 2004/063231 A1 (thermal self-crosslinking of carboxyl-containing polyvinyl acetals), EP 1606325 A1 (crosslinked with polyaldehydes polyvinyl acetals) and WO 03/020776 A1 (Crosslinked with glyoxylic polyvinyl acetals) described. The disclosure of these patent applications is fully incorporated by reference.

In the context of the present invention, terpolymers of hydrolyzed vinyl acetate / ethylene copolymers can also be used as the polyvinyl alcohol. These compounds are usually hydrolyzed to more than 98 mol% and contain 1 to 10 wt .-% based on ethylene units (eg type "Exceval" Kuraray Europe GmbH).

In the context of the present invention, the polyvinyl alcohol used can also be hydrolyzed copolymers of vinyl acetate and at least one further ethylenically unsaturated monomer.

The polyvinyl alcohols can be used in the context of the present invention purely or as a mixture of polyvinyl alcohols with different degree of polymerization or degree of hydrolysis.

The residual acetate content of the polyvinyl acetals used according to the invention is generally less than 5% by weight, preferably less than 3% by weight, more preferably less than 2% by weight and in particular less than 1.5% by weight. or 1% by weight.

The basic preparation and composition of films based on polyvinyl acetals is z. In EP 185 863 B1 . EP 1 118 258 B1 WO 02/102591 A1 . EP 1 118 258 B1 or EP 387 148 B1 described.

The films of the invention can be used in particular for the production of laminated safety glass by lamination with one or more glass sheets in a manner known to those skilled in the art. The laminated safety glasses can be used in the automotive sector z. B. as a windshield, as well as in the architectural field as transparent components or furniture used. Another use of the films according to the invention consists in the bonding of photovoltaic modules. Due to the low moisture absorption and plasticizer release of the films of the invention, these are also well suited for the production of glass / film / plastic laminates, such as for the permanent bonding of a glass sheet with a PET layer. Also, the bonding of two plastic discs, such as polycarbonate or PMMA can be carried out with the films of the invention.

The plasticizer release from the PVB film is determined experimentally under conditions which are similar to a process control in the vacuum laminator, as used for the production of photovoltaic modules. For this purpose, from a 0.76 mm thick film / pattern a Ronde cut in with a diameter of 60 mm and made flat on the floor in a tared aluminum dish with a diameter of 65 mm (neoLab aluminum tray, smooth, 65 mm, Art. No. 2-1605, weight about 2.5 g). The sample is conditioned in the dish overnight in a climate of 23 ° C / 25% RH and then left for 30 minutes at 150 ° C and 1 mbar in a vacuum oven (Heraeus, model VTR 5022). Before weighing, the dish is again conditioned overnight at 23 ° C / 25% RH. The observed weight loss relative to the original weight of the film in percent is defined as the softener delivery.

The determination of the softening temperature of the partially acetalized polyvinyl alcohol is carried out by means of differential scanning calorimetry (DSC) according to DIN 53765 using a heating rate of 10K / min in the temperature range -50 ° C-150 ° C. A first heating ramp is followed, followed by a cooling ramp followed by a second heating ramp. The position of the glass transition temperature is reflected by the second heating ramp associated measurement curve DIN 51007 determined. The DIN midpoint (Tg DIN) is defined as the intersection of a horizontal halfway up the grade with the trace. The step height is defined by the vertical distance of the two points of intersection of the central tangent with the baseline of the trace before and after glass transition.

The water or moisture content of the films is determined by the Karl Fischer method after the film has been conditioned at 23 ° C. and 85% RH for at least 24 h.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 99/45060 [0005, 0007]
• WO 2008/095571 [0005, 0007]
• EP 1527107 B1 [0030]
• WO 2004/063231 A1 [0030]
• EP 1606325 A1 [0030]
• WO 03/020776 Al [0030]
• EP 185863 B1 [0035]
• EP 1118258 B1 [0035, 0035]
• WO 02/102591 A1 [0035]
• EP 387148 B1 [0035]

Cited non-patent literature

• ASTM D 1396 [0025]
• DIN 53765 [0038]
• DIN 51007 [0038]

Claims (9)

Plasticizer-containing film comprising 60 to 90% polyvinyl acetal having a residual polyvinyl alcohol content of less than 22% by weight and 10 to 40% by weight of at least one isosorbide diester according to formula 1 as plasticizer,

wherein R ₁ , R ₂ , R ₃ , R ₅ , R ₆ , R ₇ , R ₈ , R _{10 are} each the same or different for H, alkyl chains of 1 to 5 carbon atoms and R ₄ and R ₉ are the same or different for an ester group having 1 to 20 carbon atoms in the aliphatic, aromatic or cyclic acid moiety. Plasticizer-containing film according to claim 1, characterized in that Isosorbiddiester according to formula 2

are used, wherein R ₁₁ and R ₁₂ are the same or different for aliphatic, branched or unbranched radicals having 5 to 11 carbon atoms. Plasticizer-containing film according to claim 1, characterized in that the film additionally contains 1 to 40 wt .-% based on the total amount of the plasticizer of at least one further plasticizer. Plasticizer-containing film according to claim 3, characterized in that the film additionally 1 to 40 wt .-% of at least one plasticizer selected from the group di- (2-butoxyethyl) adipate (DBEA), di- (2-butoxyethyl) sebacate (DBES), di (2-butoxyethyl) azelate, di (2-butoxyethyl) glutarate. Di (2-butoxyethoxyethyl) adipate (DBEEA), di (2-butoxyethoxyethyl) sebacate (DBEES), di (2-butoxyethoxyethyl) azelate, di (2-butoxyethoxyethyl) glutarate, di (2 hexoxyethyl) adipate, di (2-hexoxyethyl) sebacate, di (2-hexoxyethyl) azelate, di (2-hexoxyethyl) glutarate, di (2-hexoxyethoxyethyl) adipate, di (2 hexoxyethoxyethyl) sebacate, di (2-hexoxyethoxyethyl) azelate, di (2-hexoxyethoxyethyl) glutarate, di (2-butoxyethyl) phthalate, 1,2-cyclohexanedicarboxylic acid di-isononyl ester, diisononyl adipate (DINA) , Di-2-ethylhexyl adipate (DOA), triethylene glycol bis-2-ethylhexanoate (3G8) and di (2-butoxyethoxyethyl) phthalate. Plasticizer-containing film according to one of claims 1 to 4, characterized in that the softening temperature of the polyvinyl acetal is less than or equal to 77 ° C. Plasticizer-containing film according to one of claims 1 to 5, characterized in that the acetate content of the polyvinyl acetal is less than 5 wt .-%. Plasticizer-containing film according to one of claims 1 to 6, characterized in that the film has a plasticizer output of less than 4 wt .-%. Plasticized film according to one of claims 1 to 8, characterized in that is used as the polyvinyl acetal polyvinyl butyral. Use of the plasticized film according to one of claims 1 to 8 for the production of composite glazings, windshields or photovoltaic modules.