EP0000565B1 - Solutions aqueuses de copolymères, procédé pour leur préparation et application en tant que formateurs de l'enveloppe pour la fabrication de microcapsules par coacervation complexe - Google Patents

Solutions aqueuses de copolymères, procédé pour leur préparation et application en tant que formateurs de l'enveloppe pour la fabrication de microcapsules par coacervation complexe Download PDF

Info

Publication number
EP0000565B1
EP0000565B1 EP78100470A EP78100470A EP0000565B1 EP 0000565 B1 EP0000565 B1 EP 0000565B1 EP 78100470 A EP78100470 A EP 78100470A EP 78100470 A EP78100470 A EP 78100470A EP 0000565 B1 EP0000565 B1 EP 0000565B1
Authority
EP
European Patent Office
Prior art keywords
copolymer
solution
copolymers
maleic acid
aqueous
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP78100470A
Other languages
German (de)
English (en)
Other versions
EP0000565A1 (fr
Inventor
Bruno Dr. Bömer
Hildegard Dr. Schnöring
Rolf Schmidt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bayer AG
Original Assignee
Bayer AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bayer AG filed Critical Bayer AG
Publication of EP0000565A1 publication Critical patent/EP0000565A1/fr
Application granted granted Critical
Publication of EP0000565B1 publication Critical patent/EP0000565B1/fr
Expired legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/02—Making microcapsules or microballoons
    • B01J13/06—Making microcapsules or microballoons by phase separation
    • B01J13/10—Complex coacervation, i.e. interaction of oppositely charged particles
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/24—Homopolymers or copolymers of amides or imides
    • C08L33/26—Homopolymers or copolymers of acrylamide or methacrylamide
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group

Definitions

  • the invention relates to aqueous copolymer solutions, processes for their preparation and their use as shell formers for the production of microcapsules by complex coacervation.
  • the aqueous polymer solutions according to the invention are those whose polymer content is 5 to 30% by weight and consists of a mixture of (A) a copolymer with an intrinsic viscosity [ 'I] of 0.05 to 1 (dl / g) to its statistically distributed structural units 65 to 90 mol% consist of residues of acrylamide and 10 to 35 mol% of residues of maleic acid or maleic anhydride and (B) a corresponding hydrolyzed copolymer with an intrinsic viscosity [q] of 0.05 to 1.5 (dl / g) whose statistically distributed structural units accordingly consist of residues of acrylamide, acrylic acid and maleic acid, the maleic acid residues being at least partially in salt form, and which is characterized in that the weight ratio of the copolymers (A) and (B) is 1
  • the copolymers (A) can be obtained by radical copolymerization of 65-90 mol% acrylamide and 10-35 mol% maleic anhydride or maleic acid.
  • the copolymerization of acrylamide and maleic anhydride is advantageously carried out as a precipitation polymerization in organic solvents which are inert to anhydride groups.
  • organic solvents which are inert to anhydride groups.
  • Particularly cheap solvents are acetone and acetic acid esters of alcohols with 1-3 carbon atoms because of their good solvent power for the monomers and not least because of their low volatility.
  • the polymerization can be initiated with the usual free-radical initiators such as aliphatic azo compounds or organic per-compounds such as peroxides or peresters.
  • the polymerization temperature is determined by the decomposition properties of the initiator and, when using azoisobutyronitrile in batches, is 50 ° -80 ° C. In this process, the copolymers are obtained as finely divided powders and can easily be filtered off and freed of residual monomers by washing.
  • copolymerization of acrylamide and maleic acid to give copolymers (A) can be carried out both as precipitation polymerization in organic solvents and also as solution polymerization in water.
  • the precipitation copolymers can be dissolved in solvent or, after drying, in water to 5-30% by weight solutions.
  • the anhydride groups of the acrylamide-maleic anhydride copolymers pass into maleic acid groups.
  • the organic solvent is then separated off by decanting and / or distillation.
  • aqueous solutions of the copolymers (A) is the solution copolymerization of acrylamide and maleic acid in water.
  • the maleic acid can either be prepared by dissolving the appropriate amount of the andydride in water before the polymerization or used as such.
  • Suitable initiators are water-soluble per compounds such as persulfates or hydrogen peroxide, optionally in combination with a reducing agent and / or heavy metal salt. Azo compounds with sufficient water solubility are also suitable initiators. Azoisobutyronitrile is sufficiently soluble in water, especially at elevated temperatures, and is particularly preferred because it does not affect the salt content of the solutions.
  • the solution polymerization can be carried out batchwise with presentation of the entire batch or according to a semi-batch feed process with metering in of the monomers.
  • the preferred method of solution polymerization is that the aqueous solution of the monomers, which contains the initiator in dissolved or finely suspended form, is added at about 80 ° -120 ° C. with the exclusion of oxygen to a stirred charge of oxygen-free water in about 1-10 hours.
  • the azoisobutyronitrile can also be added dropwise as a solution in an organic solvent in synchronism with the monomer solution, it being possible for the solvent to be distilled off continuously. After the monomer addition has ended, the mixture is stirred for 15-120 minutes and the solution is then cooled to room temperature.
  • copolymers (A) obtained by solution polymerization still contain small amounts of residual monomers, but these generally have no adverse effect on the application properties of the solutions.
  • copolymers (A) prepared in aqueous solution already contain small amounts of acrylic acid and maleic acid salt units formed by hydrolysis during the polymerization.
  • Copolymers (A) according to the invention are obtained by copolymerization of 65-90 mol% of acrylamide and 10-35 mol% of maleic acid or maleic anhydride. Copolymers (A) of 70-85 mol% of acrylamide and 15-30 mol% of maleic acid or maleic anhydride are preferably used.
  • the copolymers (A) contain the structural units made of acrylamide and Maleic anhydride in statistical distribution and in proportions that correspond to the compositions of the monomer mixtures.
  • the free radical initiators are added in amounts of 0.1-10% by weight, preferably 0.3-3.0% by weight, based on monomers. In precipitation polymerizations, the polymer yields are generally 75-95%.
  • the copolymers (A) have intrinsic viscosity [ 1 /] of 0.05-l ', 0 [dl / g], preferably 0.08 to 0.4 [dl / g] (determined in 0.9% aqueous sodium chloride solution) .
  • the solutions of the copolymers (B)) can be obtained by heating the aqueous solutions of the copolymers (A) at temperatures of 60 ° -150 ° C., preferably 80-130 ° C. for a long time, optionally under pressure in an autoclave. Hydrolysis under reflux conditions at normal pressure is particularly preferred. Partial hydrolysis of acrylamide units occurs during heating. The resulting ammonia neutralizes some of the maleic acid building blocks and thereby causes an increase in the pH of the solution. As a result of the hydrolysis, the acrylamide-maleic acid copolymer converts into a copolymer which consists of acrylamide-acrylic acid and maleic acid units and in which the maleic acid units are at least partially in salt form.
  • Solutions of copolymers (B) according to the invention are obtained by heating solutions of the copolymers (A) according to the invention to 60 ° -150 ° C., preferably 80 ° -130 ° C. and particularly preferably to about 100 ° C. (reflux under normal pressure) until the pH of the solutions has risen to 3.8 to 4.9, preferably 4.0 to 4.6.
  • the intrinsic viscosity of the copolymers (B) determined in 0.9% aqueous sodium chloride solution, is 0.05 to 1.5 [dl / g], preferably 0.08 to 1.0 [dl / g ].
  • the solutions of the copolymers (A) and the solutions of the copolymers (B) also form coacervates on their own with gelatin, if necessary after adjusting the pH with ammonia or alkali metal hydroxide solution or with acetic acid.
  • these coacervates do not form a shell or a closed shell and / or are very sticky.
  • aqueous solutions of the copolymers (A) and (B) according to the weight ratio of the dissolved copolymers (A): (B) as 1: 2 to 20: 1, surprisingly polymer solutions are obtained which, together with gelatin, provide coacervates which form uniform, closed shells and are therefore particularly suitable for the production of microcapsules.
  • the optimal mixing ratio is mainly influenced by the composition of the copolymer (A) and by the pH of the solution of the copolymer (B), which is a measure of the degree of hydrolysis, and must be determined experimentally for each pair of copolymers.
  • solutions of copolymers (A) can also be mixed with solutions of copolymers (B) which have been obtained from copolymers (A ') with a different composition by hydrolysis (for example copolymer (A) with 70 mol% acrylamide and 30 mol% % Of maleic acid units, and copolymer solution (B) from copolymer (A ') with 80 mol% of acrylamide and 20 mol% of maleic acid units).
  • changing the pH of the polymer solution by adding ammonia or alkali hydroxide or acetic acid can have a favorable effect on the coacervation behavior.
  • microencapsulation by complex coacervation is known in principle. It is based on dispersing the encapsulating substance in finely divided form in an aqueous solution suitable for coacervate formation, and then triggering the coacervation. This is done by diluting, changing the pH or cooling or by a combination of these measures, depending on the system used.
  • the aqueous polymer solutions of the invention form complex coacervates with gelatin by dilution and / or cooling. They can be mixed, for example, in 10-15% by weight aqueous solution with a 10-15% by weight gelatin solution and coacervated by dilution and cooling. It is astonishing that such highly concentrated solutions can be used. It is also surprising that the coacervates obtained, which are a separate soft gel phase, already contain 20-30 % by weight of solids. This high solids content makes it very easy to dry the coacervates into powders. Since the coacervates form extremely coherent shells or coatings, they are particularly suitable for the production of microcapsules. During coacervation, the separate gel phase forms as a coherent layer on small, liquid or solid separate particles dispersed in the solution and envelops these particles.
  • the combination of polymer solutions according to the invention and gelatin can be used to microencapsulate a large number of liquid or solid dispersible or water-insoluble or sparingly water-insoluble or water-resistant substances.
  • Examples include: organic solvents, paraffin oils, perfume oils, silicone defoamers, Phosphoric acid esters, liquid crystals and color pigments, as well as pharmaceuticals and pesticides.
  • Example 1 a) and 1 b) are mixed in the ratios given in the table.
  • the mixtures are puffed according to the method given in Example 1 c).
  • the encapsulation behavior is said to be "good” if the oil droplets are surrounded by a closed, regularly shaped and uniformly thick shell.
  • a “medium” is a closed, irregularly shaped and unevenly thick shell.
  • a “bad” encapsulation behavior occurs if the casing is not closed and coherent, the capsules stick very strongly or no casing is formed at all.
  • Example 2 The mixed solutions are tested according to the method described in Example 1 c). The encapsulation behavior is assessed according to Example 2.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Dispersion Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Manufacturing Of Micro-Capsules (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
  • Paper (AREA)

Claims (3)

1. Solution aqueous de copolymères, dont la proportion de matière polymérique s'élève à 5-30 % en poids et qui est formée d'un mélange constitué par:
A) un copolymère de viscosité intrinsèque [η] allant de 0,05 à 1 [dl/g], dont les motifs structuraux à répartition statistique sont formés, en proportion de 65 à 90 moles %, de restes d'acrylamide et, en proportion de 10 à 35 moles %, de restes d'acide maléique ou d'anhydrique d'acide maléique, et
B) un copolymère hydrolysé correspondant de viscosité intrinsèque [1]] allant de 0,05 à 1,5 [dl/g] dont le motif structural à répartition statistique est formé, d'une manière correspondante, de restes d'acrylamide, d'acide acrylique et d'acide maléique, les restes d'acide maléique étant présents au moins en partie sous la forme de sel,

caractérisée en ce que le rapport en poids des copolymères A et B a une valeur de 1:2 à 20:1.
2. Procédé de production de la solution aqueuse de copolymères suivant la revendication 1, caractérisé en ce que:
a) pour la production du copolymère (A), on dissout les monomères dans un solvant organique ou dans l'eau, on les polymérise à 50-120°C avec des initiateurs radicalaires et le cas échéant, on isole le produit de polymérisation et on le dissout dans l'eau et
b) pour la production du copolymère (B), on hydrolyse une partie du copolymère (A) par chauffage de sa solution aqueuse à une température de 60 à 150°C jusqu'à ce que le pH ait atteint une valeur de 3,8 à 4,9, puis
c) on réunit les deux solutions de copolymères dans un rapport du copolymère (A) au copolymère (B) de 1:2 à 20:1.
3. Utilisation de la solution aqueuse de copolymères suivant la revendication 1 comme composant pour la formation d'enveloppes dans la production de microcapsules par coacervation complexe.
EP78100470A 1977-07-30 1978-07-21 Solutions aqueuses de copolymères, procédé pour leur préparation et application en tant que formateurs de l'enveloppe pour la fabrication de microcapsules par coacervation complexe Expired EP0000565B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19772734577 DE2734577A1 (de) 1977-07-30 1977-07-30 Polymerloesungen
DE2734577 1977-07-30

Publications (2)

Publication Number Publication Date
EP0000565A1 EP0000565A1 (fr) 1979-02-07
EP0000565B1 true EP0000565B1 (fr) 1981-04-29

Family

ID=6015335

Family Applications (1)

Application Number Title Priority Date Filing Date
EP78100470A Expired EP0000565B1 (fr) 1977-07-30 1978-07-21 Solutions aqueuses de copolymères, procédé pour leur préparation et application en tant que formateurs de l'enveloppe pour la fabrication de microcapsules par coacervation complexe

Country Status (6)

Country Link
US (1) US4181639A (fr)
EP (1) EP0000565B1 (fr)
JP (1) JPS5426843A (fr)
DE (2) DE2734577A1 (fr)
DK (1) DK335578A (fr)
IT (1) IT1106614B (fr)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3016170A1 (de) 1980-04-26 1981-10-29 Bayer Ag, 5090 Leverkusen Mikrokapseln mit definierter oeffnungstemperatur, verfahren zu deren herstellung sowie deren verwendung
US4784879A (en) * 1987-07-20 1988-11-15 Dow Corning Corporation Method for preparing a microencapsulated compound of a platinum group metal
USRE33749E (en) * 1987-07-20 1991-11-19 Dow Corning Corporation Storage stable heat curable organosiloxane compositions containing microencapsulated platinum-containing catalysts
US5268419A (en) * 1988-01-28 1993-12-07 Rohm And Haas Company Fast curing binder for cellulose
US5314943A (en) * 1990-11-30 1994-05-24 Rohm And Haax Company Low viscosity high strength acid binder
ES2125306T5 (es) * 1992-06-04 2006-04-01 Arjo Wiggins Limited Material de registro piezosensible.
GB9522233D0 (en) 1995-10-31 1996-01-03 Wiggins Teape Group The Limite Pressure-sensitive copying paper
DE19634393A1 (de) * 1996-08-26 1998-03-05 Bayer Ag Verfahren zur Herstellung vernetzter Polymerisate
DE19840583A1 (de) 1998-09-05 2000-03-09 Bayer Ag Mikrokapsel-Formulierungen
US6653256B1 (en) 1999-08-24 2003-11-25 Bayer Aktiengesellschaft Microcapsule formulations
US7919331B2 (en) * 2006-12-21 2011-04-05 Silver Lake Research Corporation Chromatographic test strips for one or more analytes

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1900865A1 (de) * 1969-01-09 1970-08-27 Bayer Ag Verfahren zur Herstellung von Mikrokapseln
US3635915A (en) * 1969-11-28 1972-01-18 Deering Milliken Res Corp Copolymers of maleic acid and acrylic acid
DE2010117C3 (de) * 1970-03-04 1979-06-07 Bayer Ag, 5090 Leverkusen Verfahren zur Herstellung von thermoreversiblen Koazervaten
DE2060571A1 (de) * 1970-12-09 1972-06-15 Bayer Ag Verfahren zur Herstellung von thermoreversiblen Koazervaten
DE2217696C3 (de) * 1972-04-13 1979-06-28 Basf Ag, 6700 Ludwigshafen Verteilungsstabile Dispersionen von Mikrokapseln

Also Published As

Publication number Publication date
DK335578A (da) 1979-01-31
DE2860645D1 (en) 1981-08-06
JPS627948B2 (fr) 1987-02-19
EP0000565A1 (fr) 1979-02-07
JPS5426843A (en) 1979-02-28
IT7850520A0 (it) 1978-07-28
DE2734577A1 (de) 1979-02-08
IT1106614B (it) 1985-11-11
US4181639A (en) 1980-01-01

Similar Documents

Publication Publication Date Title
DE3017576C2 (fr)
DE2840010C3 (de) Pfropfmischpolymerisate
DE2437629C3 (de) Verfahren zur Herstellung von unlöslichen in Wasser nur wenig quellbaren Polymerisaten von N-Vinyllactamen
DE1795126C3 (de) Verfahren zur Gewinnung von wasserlöslichen Acrylamidpolymerisaten
EP0000565B1 (fr) Solutions aqueuses de copolymères, procédé pour leur préparation et application en tant que formateurs de l'enveloppe pour la fabrication de microcapsules par coacervation complexe
DE1795078B2 (de) Wäßrige Polytetraftuoräthylen-Dispersionen, Verfahren zu ihrer Herstellung und ihre Verwendung
DE69017846T2 (de) Verfahren zur herstellung von harzen mit hoher wasserabsorption.
EP0011190B1 (fr) Perles de polymerats réticulés contenant une charge
DE2602917C2 (de) Verfahren zur Herstellung eines festen Polymeren aus Vinylpyrrolidon und seine Verwendung
DE2461083A1 (de) Verfahren zur mikrosuspensionspolymerisation von vinylhalogeniden
DE3823729A1 (de) Verfahren zur herstellung eines harzes mit einem hohen wasserabsorptionsvermoegen
DD141029B1 (de) Nadelauswaehlmechanismus fuer automatische strickmaschinen
DE2236456B2 (de) Verfahren zum herstellen eines gemischten polymerisats
DE1123110B (de) Verfahren zur Polymerisation von wasserloeslichen Monomeren
CH635849A5 (de) Verfahren zur homo- oder copolymerisation eines vinylchloridmonomers oder einer mischung eines vinylchloridmonomeren und comonomeren.
DE4033219A1 (de) Verfahren zum agglomerieren eines polymerpulvers
EP0002285B1 (fr) Procédé de préparation de copolymères réticulés et emploi des produits ainsi obtenus dans l'impression de textiles
DE2260957A1 (de) Verfahren zur homo- oder copolymerisation von vinylchlorid
DE3877385T2 (de) Wasser-quellbare vernetzte polymere und verfahren zu deren herstellung.
DE1092200B (de) Verfahren zur Herstellung von Mischpolymeren aus Vinylalkohol und Acrylsaeureestern
DE2060571A1 (de) Verfahren zur Herstellung von thermoreversiblen Koazervaten
DE2010117B2 (de) Verfahren zur Herstellung von thermoreversiblen Koazervaten
DE2017451C3 (de) Verfahren zur Herstellung vernetztet Polycarbonsäuren
DE2023971C3 (de) Verfahren zur Polymerisation von Vinylchlorid und dessen Gemischen mit Verbindungen des Vinyltyps in Masse und so erhaltende Homo- bzw. Mischpolymerisate
DE1570291A1 (de) Verfahren zur Herstellung von Polymerisaten

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed
AK Designated contracting states

Designated state(s): BE CH DE FR GB NL SE

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Designated state(s): BE CH DE FR GB NL SE

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19810731

Year of fee payment: 4

REF Corresponds to:

Ref document number: 2860645

Country of ref document: DE

Date of ref document: 19810806

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: CH

Payment date: 19810930

Year of fee payment: 4

Ref country code: BE

Payment date: 19810930

Year of fee payment: 4

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19820722

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: CH

Effective date: 19820731

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Effective date: 19830121

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19910619

Year of fee payment: 14

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19910627

Year of fee payment: 14

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19910709

Year of fee payment: 14

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19910731

Year of fee payment: 14

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19920721

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19930201

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee
GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19920721

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Effective date: 19930331

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19930401

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

EUG Se: european patent has lapsed

Ref document number: 78100470.0

Effective date: 19850611

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT