WO1998047953A1

WO1998047953A1 - Adhesive applicator crayon

Info

Publication number: WO1998047953A1
Application number: PCT/US1997/006713
Authority: WO
Inventors: Peter Spiros Columbus; John Anderson
Original assignee: Elmers Products Inc
Current assignee: Elmers Products Inc
Priority date: 1997-04-23
Filing date: 1997-04-23
Publication date: 1998-10-29
Anticipated expiration: 1999-10-23
Also published as: AU2738597A; CA2256705A1

Abstract

Adhesive compositions exhibiting fast cure time in solid form, e.g. in the form of an applicator crayon or glue stick. The adhesive exhibiting polymer of the composition is based on a mixture of critical amounts of high molecular weight polyvinylpyrrolidone polymer, with a lower molecular weight polyvinylpyrrolidone polymer, with water, an organic solvent, and a salt of a long-chain fatty acid, e.g. sodium stearate. Color indicators and other optional ingredients, e.g. mildewcide, can be included.

Description

ADHESIVE APPLICATOR CRAYON

Background of the Invention

1. Field of the Invention

Fast setting adhesive formulations in an easy applicator form

are desirable for office, school and home consumers. The present invention

provides a polyvinylpyrrolidone (hereinafter "PVP")-based composition in

solid form, e.g. glue stick or crayon, which is easy to apply, bonds faster and

is safe to use. The adhesive bonds porous substrates to which they are applied,

such as paper, fabrics, polystryene foam, wood and similar porous substrate

materials.

2. Description of the Related Art

U.S. Patent 3,576,776, issued in 1971, contains a disclosure of

an invention for adhesive applicator crayons comprising a shape-giving base

consisting of a gel-forming salt, a liquid, and an adhesive component. Among

the adhesives are listed salts of various acids, amides, and N-alkyl substituted

amides including polyvinylpyrrolidone. The disclosure of U.S. patent

3,576,776 was said to be an improvement over known adhesive applicator

crayons prepared from rubber, resins and waxes, which required that surface

layers must be rubbed off from such crayons under relatively high pressure in order to carry out the spreading of the adhesive.

Later solid adhesive compositions, such as those disclosed in

U.S. Patents 4,073,756 and 4,075,830, were said to avoid the problem inherent in the crayons of U.S. Patent 3,576,776, the long time it took to produce the

adhesive composition and the high viscosity of the adhesive composition (e.g. higher than 150,000 cps) which made it difficult to fill the adhesive composition in containers.

The later patents thus used water soluble or water dispersible

polymers having adhesive properties in combination with N-fatty acid acylated

arnino acids or salts thereof and water, or a mixture of water and one or more

organic solvent(s) and/or plasticizer(s). The water dispersible or water soluble

polymers having adhesive properties listed, among others, homopolymers or

copolymers having a carboxyl group or a carboxylic anhydride group, where

the proportions of the carboxyl and/or carboxylic anhydride group containing

monomer is preferably about 30 to 100 mol %.

These, and other prior art formulations (the entire disclosures

of all of which are herein incorporated by reference), were still slow to exhibit

adhesive properties when dispensed, i.e. slow to exhibit paper tear when

applied to bond paper.

Among other properties, the present invention provides strong

final bonds and a pH generally in the range of about 8.5 to about 9.5.

However, in the embodiments of the invention where a color indicator is used,

the hue or intensity of the color is enhanced by having a pH more alkaline than the range given above, e.g. up to a pH of about 11, e.g. 10.9 - 11.1.

Object of the Invention

It is thus an object of the invention to provide new adhesive

compositions exhibiting fast adhesive properties (e.g. fast initial tear of paper)

and strong final bonds. It is a further object of the invention to provide adhesive compositions

in the form of solids at ambient conditions, i.e. glue sticks or applicator

crayons which exhibit fast adhesive properties when applied to a substrate and

suitable for bonding paper, fabric, polystyrene foam and similar materials.

It is a still further object of the invention to provide bonded substrates,

such as paper, fabric, and similar porous materials, bonded with the adhesive

compositions of the invention.

Summary of the Invention

Water-based solid adhesive crayons which contain water in a mixture

comprising a relatively low molecular weight (all references to "molecular weight" in this Specification, claims and Abstract are intended to mean

"weight average molecular weight" unless otherwise designated) water

dispersible or water soluble polymer, e.g. polyvinylpyrrolidone polymer, i.e. a molecular weight below about 1,300,000, and a critical amount of a

relatively high molecular weight water dispersible or water soluble polymer,

e.g. polyvinylpyrollidone polymer, i.e. a molecular weight above 1,300,000.

By critical amounts is meant sufficient amounts of the high molecular weight

(polyvinylpyrollidone) polymer to impart 1.) a fast film- forming or setting

property, 2.) a strong final bonding property, and 3.) an additional firmness to the crayon adhesive to reduce "crumbling" when pressure is applied to the

crayon, while keeping the water content of the adhesive at 50 weight percent,

or more, to ensure easy spreading and performance during use and after storage. Optional ingredients include a plasticizer for the

(polyvinylpyrollidone) polymers to impart a degree of flexibility to the dry adhesive film, a preservative to protect the adhesive from attack by

microorganisms, a long chain fatty acid salt to impart a solid gel property to

the adhesive, and a color indicator for the purpose of indicating when an

applied film of adhesive has dried.

This composition may be formulated so as to exhibit physical

properties of a solid, e.g. it may be formulated so as to be suitable for

application in the form of a crayon or glue stick to porous substrates to be

bonded. The composition is preferably formulated so as to be satisfactorily

extruded from and retracted into a container, exhibit good spreadability

without being "runny" or dispensing excessive adhesive to a substrate nor so

firm that the crayon or adhesive stick "crumbles" due to the requirement to

exert excessive pressure during application of the crayon/stick to a substrate

to effect adequate spreading of the adhesive on the substrate.

It is also within the purview of the invention to provide substrates

bonded with the formulations of the invention.

Detailed Description of the Invention

The composition of matter of this invention exhibits adhesive

properties and is formulated of components (A), (B), (C), and (D), wherein (A) is an aqueous vehicle, typically water or aqueous emulsions/dispersions of one

or more of components (B), (C), (D) and/or any optional components; (B) is at least one water soluble or water dispersible polymer, e.g.

polyvinylpyrollidone (hereinafter "PVP") polymer exhibiting adhesive

properties having a molecular weight below about 1,300,000, (C) is a salt of a long chain fatty acid or a precursor thereof which forms a salt of a long chain fatty acid when combined with the other components of the compositions of

matter of this invention and (D) is a water soluble or water dispersible

polymer, e.g. a PVP polymer having a molecular weight above about

1,300,000, preferably above about 2,000,000 most preferably of at least about

2,800,000. Suitable polymers for component (B) include homopolymers or

copolymers of the types identified in U.S. Patents 4,073,756 or 4,954,544,

although PVP is particularly preferred. Although higher molecular weight

polymers of component (D) can be of the same type of polymer as component

(B), it is preferred that the high molecular weight polymer be PVP.

When it is desirable, certain optional ingredients may be included in

the composition of matter of the invention, e.g. a mildewcide and/or fungicide,

solvents for the adhesive exhibiting polymeric components, e.g. alcohols, such

as glycerol or polyglycols for PVP, pigments and/or dyes to impart a

permanent color, and/or a color indicator, such as phenolphthalein or

thymolphthalein, for indicating when the applied film is dried.

Generally, the components of the invention may be combined over a

wide range. However, in order to formulate the composition of matter in solid

form, e.g. suitable for use, as an adhesive applicator stick or crayon, it is

preferable that the composition contain not less than about 50% nor more than

about 80% (all % in this application are by weight unless otherwise noted) by

weight of component (A) (wherein (A) is water). If (A) is an aqueous formulation containing one or more components (B)-(D), or having optional components, the amount of (A) can be adjusted so as to be greater than, or lesser than, the amounts indicated. Although it is preferable that the composition contain not less than about 50%, preferably not less than about

60% of component (A) (where (A) is water) this amount can be adjusted

lower, e.g. 45% or less though not exhibiting the most preferred properties of

the adhesive stick of the invention. The presence of plasticizers, solvents or

mixtures thereof for the water dispersible polymers may also decrease the

requirements for component (A) to be present in an amount of not less than

50%, because such plasticizers/solvents enhance the spreadability properties.

As with the case of the maximum content of component (A), when (A) is an

aqueous formulation containing one or more of components (B)-(D), or any

optional components, the amount of (A) will be adjusted accordingly.

Component (B) is at least one polymer exhibiting adhesive properties,

preferably a polyvinylpyrrolidone (PVP) of relatively low molecular weight,

e.g. below about 1,300,000. PVP polymers are commercially available in

several viscosity grades, ranging from very low to very high molecular weight.

This range, coupled with solubility in water, aqueous and organic solvent

systems and its non-toxic character, give PVP great flexibility in the

compositions and applicator solid forms of the present invention.

Commercially available PVP suitable for use in this invention as

components (B) or (D) are available from GAF Chemicals Corporation, International Specialty Products, of Wayne, N.J., U.S.A., under the tradenames PVP K-90 and PVP K-120, each having an off-white powder appearance.

PVP K-90 has a viscosity average molecular weight of 630.000 (performed at

25 °C, in H₂0, using Mark Houwink constants of K = 1.4 x 10^"4 and a = 0.7), a weight average molecular weight (Wt.Avg.MW) of 1,280,000 (obtained by low angle laser light scattering (LALLS) photometry) and a K-value of 88-

100. PVP K-120 has a viscosity average molecular weight of 1,450,000

(performed under the same conditions above); a weight average molecular

weight of 2,800,000 (performed by LALLS photometry as above) and a Re¬

value of 115-125. These same polymers are also available as solutions from

the same source. Other commercially available PVP in powder or solution

form can be obtained from BASF Corporation of Mount Olive, N.J., U.S.A.

under the registered trademark LUVISKOL over a wide range of molecular

weights. Luviskol K-90 has a weight average molecular weight of 1,200,000;

Luviskol K-80 has a weight average molecular weight of 900,000 and

Luviskol K-60, K-30 and K-77 have lower molecular weights. These products

are described in the Luviskol® Polyvinylpyrollidone Polymers catalog by

BASF corporation and PVP Polyvinylpyrollidone Polymers catalog by ISP

(International Specialty Products) GAF corporation, the entire disclosures of

which are herein incorporated by reference.

It is to be expressly understood that the identification of the

aforementioned commercially available sources of PVP polymers and/or

solutions is by way of illustration only and not by way of limitation; as other

commonly available sources or synthesized polymers may be used in the

invention without departing from the spirit or scope of the appended claims.

Preferably, in the compositions of the invention, component (B) is present in amounts of at least about 12% but not more than about 26%. More than one low molecular weight polymer can be used as component (B). When

more than one low molecular weight adhesive-exhibiting polymer is present, it is preferable that the higher molecular weight polymer of such low

molecular weight polymers is present in an equal or greater amount.

Component (C) is generally present from about 3% to about 10%,

based on the total weight of the composition, preferably in the range of about

6% to about 8%. Component (C) is a long chain (i.e. C₁₅-C₂₆) fatty acid,

preferably in the form of a salt with an alkali-metal or alkaline earth metal, e.g.

Li, Na, K, Ca, Sr, Ba, most preferably sodium stearate. It enhances spreading

properties when the crayon or glue stick is rubbed against a porous substrate.

Component (D) is a high molecular weight (e.g. above about a

molecular weight of 1,300,000, preferably above 2,000,000, most preferably

at least 2,800,000) polymer, e.g. PVP. The amount of component (D) is

sufficient to impart fast setting properties, e.g. preferably in less than 20

seconds, preferably less than 15 seconds to the film applied to a porous

substrate from the glue stick of the invention. However, the amount of

component (D) should not be so great as to induce crumbling when pressure

is applied to the glue stick upon rubbing the stick on the porous substrate. The

amount of component (D) will vary with the molecular weight of the polymer,

lower amounts being required with the highest molecular weights. In general, component (D) may be present in an amount of from about 0.5% to about

10%, preferably about 0.5% to about 4%. Most preferably, the amount of component (D) is at least 0.5 wt %, preferably at least 0.7 wt %, most

preferably at least about 1 wt %.

When a solvent for the water dispersible polymer, e.g. PVP, is present,

it is preferably an organic solvent. Preferably the solvent is an alcohol, more preferably an alcohol selected from the group consisting of glycerol,

polyglycols, especially low molecular weight polyglycols, e.g. propylene

glycol and mixtures thereof, though most preferably, glycerols and propylene

glycol. Other solvents, including acids, ketone and ether alcohols, lactones,

lactams, certain esters, ketones and chlorinated hydrocarbons; esters and

nitroparaffins are known solvents for PVP. The solvent is present in amounts

ranging from about 3% to about 8%, preferably about 3.2% to about 7%.

Plasticizers for the water soluble/dispersible polymers may also be

included in the formulations of the inventions. Low molecular weight

polyethylene glycols, e.g. having a M.W. of 400 or less, are particularly good

plasticizers.

The compositions of the invention can be made by mixing components

(A)-(D), and any optional components, in any order. During this mixing,

temperature can be elevated to 85-95 °C and mixing continued with slow

agitation until components (B) and (D) are completely dissolved (within about

15 minutes) and the component (C) and any optional ingredients added and

mixed until dissolved completely. Alternatively, components (A) can be

mixed with (C) and/or any optional components and then mixed with the polymer components (B) and (D). Still further components (A), (B) and (D)

can be mixed, or components (B) and (D) can be in solution/dispersion form,

before being mixed with any other component. The resulting composition can be extruded directly into glue stick containers or drawn off into drums for

storage to be reheated and used at a future date. When an optional component for controlling microorganisms is added, it may take the form of a mildewcide and/or fungicide. Suitable substances are commercially available, such as the mildewcide sold under the trademark

"DOWICIL 150" (available from Dow Chemical Corporation, Midland, Michigan, USA) in an effective amount, e.g. as little as 0.18 wt % to 0.20 wt

%.

Permanent color can be imparted to the composition of the invention by including pigments and/or dyes as an optional component.

When a color indicator is added for the purpose of indicating when the film has dried, the freshly applied adhesive has a color, e.g. blue, which fades

to colorless when the adhesive has dried, e.g. in about 9-15 seconds. When the color indicator is present in combination with a permanent color, the color will

change from the as applied to dried adhesive, rather than fade to colorless.

As suitable indicators can be used phenolphtalein (chemical name 3,3- bis(4-hydroxyphenyl)- 1 -(3H)-isobenzofuranone) orthymolphthalein (chemical

name 3,3-bis[4-hydroxy-2-methyl-5-(l-methylethyl)phenyl]-l-(3 H)- isobenzofuranone. These indicators are commerically available such as

phenolphthalein and its alkyl derivatives. The indicators are present in an

effective amount to indicate a change between a color and colorless phase and generally are present in an amount of not more than 2 wt % preferably from

about 0.01 to about 0.5 wt %. As mentioned hereinabove, higher alkalinity enhances the intensity of these indicators to impart a stronger hue to the color

exhibited. -11-

The advantages of the compositions of the invenuon will be illustrated

by the follo mg Examples and Comparative Examples. In the Examples_,

can be seen that the properties of the composition, especially proper_ties of

extension and retractⁱon of the composition from a container and mos_t

importantly ⁱts spreading and setting characteristics_, can be ta_ilored by proportioning the components.

'Propylene glycol

² tAvg.M = 55,000

*Glue stick separated from the carry platform.

It can readily be seen that the compositions of matter of the present

invention, in the form of glue sticks or crayons, provide a fast setting, non-

toxic composition suitable for adhering porous substrates.

It is to be understood that, in die specification and accompanying

claims, the formulations are considered to consist of components of two

phases, e.g. liquids and solids. The liquid phase component is water or

aqueous phase and all other components are considered solids, even though

some components used in the invention may be thought of as liquids. The

percentage of solids can thus be calculated by subtracting me percentage of

liquid component from 100%. For example, if the liquid phase is 70% by

weight the solid phase is 30% by weight (100% - 70% = 30%). It thus can be

appreciated that the formulations of the invention comprise a minor to

equivalent percentage of solids to liquid, but yet are fast setting, strong bond

forming adhesive compositions.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

Claims

We Claim:

1. A composition of matter comprising a mixture of the following

components (A)-(D):

(A) about 45% to about 80% by weight water;

(B) about 12% to about 26% by weight of at least one water soluble

or water dispersible polymer exhibiting adhesive properties, said polymer

having a molecular weight of less than about 1,300,000;

(C) a long-chain fatty acid, or a salt of a long-chain fatty acid, in an

amount of from about 3% to about 10%; and

(D) a high molecular weight water soluble or water dispersible

polymer, said high molecular weight polymer having a molecular weight of

at least 1,300,000 and being present in an amount sufficient to impart fast film

forming and strong final bonding property to the composition.

2. The composition of claim 1 wherein the component (B) is at

least one polyvinylpyrrolidone polymer.

3. The composition of claim 1 wherein component (B) comprises at least two polyvinylpyrrolidone polymers, the polymers having different

molecular weights.

4. The composition of claim 3 wherein the weight ratio of the

polyvinylpyrrolidone of lower molecular weight to the polyvinylpyrrolidone

of greater molecular weight is not greater than about 1 :1.

5. The composition of claim 1 wherein component (D) is present

in an amount of from about 0.5 to about 4% by weight.

6. The composition of claim 1 wherein component (C) is sodium stearate.

7. The composition of claim 1 further comprising a component

selected from the group consisting of glycerol, propylene glycol and mixtures

thereof.

8. The composition of claim 1 further including a color indicator.

9. An adhesive crayon comprising the composition of claim 1 in

solid form.

10. An adhesive crayon according to claim 9 wherein the water

content is at least 50% by weight.

11. Porous substrates adhered by an adhesive formulation of claim

1.

12. The porous substrates of claim 11 wherein the porous substrate

is selected from the group consisting of paper, wood, fabric and polystyrene

foam.

13. A composition of matter in solid form at ambient conditions

comprising:

(A) from about 45% to about 80% by weight of water;

(B) from about 12% to about 26% of at least one

polyvinylpyrrolidone polymer of molecular weight less than about 1 ,300,000.

(C) from about 3% to about 10% of a long chain fatty acid

or salt thereof; and (D) from about 0.5%> to about 4%> of a polyvinylpyrrolidone

polymer having a molecular weight in the range of from about 1,300,000 to

about 2,800,000.

14. The composition of claim 13 wherein component (A) is present

in an amount of at least 50% by weight.

15. The composition of claim 13 further comprising an effective

amount of a mildecide.

16. The composition of claim 13 further comprising a color

indicator in an amount of from about 0.01% to 0.5% by weight.

17. Porous substrates adhered by an adhesive formulation of claim

13.

18. The porous substrates of claim 16 wherein the porous substrate

is selected from the group consisting of paper, wood, fabric and polystyrene

foam.

19. The composition of claim 13 further comprising at least one

component selected from the group consisting of solvents, plasticizers and

mixtures thereof.

20. The composition of claim 13 wherein component (C) is sodium

stearate.

21. The composition of claim 13 further comprising a color

indicator selected from the group consisting of phenolphthalein and

thymolphthalein.

22. An adhesive crayon comprising the composition according to

claim 13 in solid form wherein the solid phase is from about 30% to about

50% by weight.