GB2376402A

GB2376402A - Multi layered seed mat

Info

Publication number: GB2376402A
Application number: GB0209576A
Authority: GB
Inventors: Beadley Allen Aulick; Robert Lee Barcus; David Bradley Henning; Jody Lynn Hoying; Bruce Prentiss Murch
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 2001-04-27
Filing date: 2002-04-25
Publication date: 2002-12-18
Also published as: GB0209576D0

Abstract

A seed mat 100 has a ground facing layer 101 and a water insoluble fibrous layer 105 above the ground facing layer. The ground facing layer includes a water soluble substrate 102 containing seeds 103. The seed mat is placed on the ground and watered. The water soluble substrate 102 dissolves, depositing the seeds 103 on the ground. The water insoluble fibrous layer 105 acts as a mulch to prevent excessive water loss. A process for forming the mat is also disclosed in which the layers are bonded together and apertures created through the layers to allow penetration of the germinating seed.

Description

SEED MATS AND METHODS FOR THEIR PREPARATION AND USE FOR GROWING PLANTS FIELD OF THE INVENTION This invention relates to seed mats and methods for their preparation and use.

More particularly, this invention relates to multilayer seed mats for planting seeds, methods for preparing the multilayer seed mats, and methods for growing plants, particularly grass, using the multilayer seed mats.

BACKGROUND OF THE INVENTION Conventional planting of grass, flower, and other seeds by hand or machine (e. g., spraying) frequently is inefficient. Products such as loose seeds, mulch, or straw, as well as products combining mixtures of seeds and mulch, are time consuming and difficult to apply. Other products include wood fiber mats that can be used for erosion control and ground cover. Typically, a consumer will seed the ground and then cover the seeds with one of these products. This is time consuming and inconvenient in that the consumer must undergo a multiple step process in applying the seeds first and then separately applying a mat. Additionally, these types of products require frequent watering, sometimes twice per day for as long as three weeks after application, and frequently result in patchy, nonuniform plant growth.

Seed mats provide benefits over the direct seeding products and methods described above. The placement of materials is simpler and less time consuming. Some seed mats have a mulch layer with seeds dispersed therein. The seed mats are placed on the ground in the area where plant growth is desired. When these seed mats are watered, seeds germinate within the mat. However, these seed mats may suffer from the drawback that if there are gaps between the mat and the ground, seeds germinate and die before the roots reach the ground.

Other seed mats have a water-soluble fabric and/or fiber layer with seeds coated on top, where the fabric and/or fiber layer is placed towards the ground when the mat is used. One such seed mat has seeds sprinkled on top of foam droplets adhered to a fabric layer. A hydrophobic agent is added to the fabric layer to prevent the fabric from absorbing the foam, which has specific bubble size requirements. This seed mat appears to be difficult and costly to fabricate. Furthermore, the hydrophobic agent may prevent water from the ground from adequately reaching the seeds.

Many seed mats have optional reinforcing layers such as nylon or plastic mesh or paper layers coated over a layer containing the seeds. Some reinforcing layers used to increase integrity are not biodegradable. One seed mat has layers of randomly oriented, unmodified, natural straw-like fibers, water-soluble adhesive, and viable seeds and fertilizer on a paper reinforcing backing. The mat is made by feeding the fibers onto the paper reinforcing backing, spraying adhesive onto the fibers and spreading seed onto the adhesive.

Furthermore, existing seed mats also suffer from the drawbacks that some lack sufficient integrity to be conveniently applied without excessive disintegration either in shipping or in use. Other seed mats are sufficiently inflexible that gaps form between parts of the mat and the ground. Gaps result in seeds germinating and dying because the roots do not reach the soil, again resulting in patchy, nonuniform growth. Furthermore, many seed mats are cost prohibitive for consumer use due to the costs of materials of construction and production.

SUMMARY OF THE INVENTION This invention relates to seed mats, methods for their preparation, and methods for growing plants using the seed mats. The seed mat comprises: a. a ground facing layer comprising a water soluble substrate and seeds, b. optionally an adhesive layer positioned between at least a portion of the ground facing layer and a water insoluble fibrous layer, c. a water insoluble fibrous layer above the ground facing layer, and d. optionally a top layer of soluble material or insoluble material for protection and handling of the water insoluble fibrous layer.

The seed mat is typically made by preparing the water insoluble fibrous layer, preparing the ground facing layer, and thereafter joining the layers. This invention further relates to methods for aperturing and/or mechanically weakening the individual layers or consolidated mat.

This invention further relates to a method for growing plants using the seed mat.

The seed mat is placed on the ground with the ground facing layer towards the ground.

The seed mat is then watered to grow plants.

The seed mats according to this invention offer several advantages over existing seed mats. The seed mats of this invention allow detachment of seeds from the mat to the ground because the substrate and any optional binders and/or adhesives dissolve sufficiently when the seed mat is watered. Without wishing to be bound by theory, it is thought that this dissolution removes potential inhibitors of seed germination and growth.

Furthermore, the water insoluble fibrous layer and any optional top layer have sufficient porosity to allow seedling growth and maintain moisture on seeds and seedlings during dry periods. The seed mats according to this invention are flexible and conform to the contour of the ground. Without wishing to be bound by theory, it is thought that the flexibility will help promote germination and growth and prevent seeds from washing away during periods of rain.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a seed mat according to this invention.

Figure 2 is a schematic representation of an exemplary process for bonding, aperturing, and weakening the mat described by the present invention.

Figure 3 is an enlarged perspective illustration of a patterned calendaring arrangement.

Figure 4 is an enlarged perspective illustration of a cross direction incremental stretching system of the present invention.

Figure 5 is an enlarged perspective illustration of an alternative machine direction incremental stretching system of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

All U. S. Patents cited herein are hereby incorporated by reference. All amounts, percentages, and ratios are by weight unless otherwise indicated.

Definitions The following is a list of definitions as used herein.

"Basis weight"means amount of the fibers in the water insoluble fibrous layer per unit of area.

"Dispersible"means the product will break apart into smaller components or dissolve, or a combination thereof. Rate of Dispersibility can be measured according to the test method described below in Reference Example 8.

"HSPAN"means starch grafted with hydrolyzed poly (acrylonitrile).

"Mil"means one thousandth of an inch.

Seed Mats This invention relates to seed mats. The seed mat comprises: a. a ground facing layer comprising a water soluble substrate and seeds, b. optionally an adhesive layer positioned between at least a portion of the ground facing layer and a water insoluble fibrous layer, c. a water insoluble fibrous layer above the ground facing layer, and d. optionally a top layer of soluble material or insoluble material.

The mat is inexpensive to manufacture and convenient to install.

Ground Facing Layer The ground facing layer comprises a substrate and seeds. The seeds may be combined with the substrate by any convenient means. For example, the seeds may be coated on the substrate opposite the water insoluble fibrous layer, the seeds may be dispersed in the substrate, the seeds may be coated on the water insoluble fibrous layer and then coated over with the substrate, the seeds may be applied directly to a water soluble layer by partialy solubilizing the layer, or the seeds may be constrained between layers of substrate.

Substrate The substrate comprises a water soluble polymer. Preferably, the water soluble polymer is biodegradable. Examples of suitable water soluble polymers include naturally occurring polymers such as polysaccharides, synthetic water soluble polymers including polymers and copolymers derived from ethylene oxide, acrylamides, acrylic acid and the like; and combinations thereof. Examples of preferred synthetic water soluble polymers are poly (vinyl alcohols), poly (ethyleneglycols), poly (ethylene oxides), poly (acrylamides), poly (N-alkyl or N, N-dialkyl acrylamides), poly (acrylic acids), poly (vinyl pyrolidones), poly (hydroxyalkyl acrylates), chemically modified starches, and combinations thereof.

Examples of preferred naturally occurring polymers are starches. Preferably, the water soluble polymer is poly (vinyl alcohol).

The substrate has a form typically selected from the group consisting of a foam or a film. The preferred embodiments of the ground facing layer can be described by various properties including solubility, composition, the form of the substrate (e. g. , generally foams are thicker than films), thickness, and tensile strength of the layer.

One important property of the substrate is its water solubility. Without wishing to be bound by theory, it is thought that if a gap exists between the ground facing layer and the ground, seeds attached to the mat may germinate and die before the roots can reach the ground. Therefore, the substrate dissolves sufficiently that the seeds no longer adhere to the mat after the mat is watered, e. g. , the seeds will come off the mat within the time a user waters the mat after installing it. The substrate should dissolve in about 2 milliliters of cold tap water per square inch of substrate without agitation, preferably within about 15 minutes, more preferably within about 10 minutes, most preferably in less than about 5 minutes of contact with the water.

A preferred film comprises poly (vinyl alcohol). The solubility of such films is dictated by several factors, such as molecular weight of the polymer, degree of hydrolysis (from its parent polymer, polyvinylacetate), various additives, and the thickness of the film. Typically, the ground facing layer is less than about 5 mils, more preferably less than about 2 mils, most preferably about 1 mil or less. The lower limit is dictated more by manufacturing feasibility of the film and by its integrity in handling. Some examples of commercially available poly (vinyl alcohol) films available from Chris Craft Industrial

Products, Inc. are shown in Table 1 where the rank order of solubility is indicated by the number of plus (+) signs.

Table 1 Solubility Ranking of Poly (vinyl alcohol) Films

Product Thickness (mils) Solubility E6030 1. 0-W-+++ M7031 2. 0 -H+ M8630 1. 5 ++ M8630 2. 0 ++ M8630 3. 0 + M8630 3. 0 + M7031 3. 0 +

Types of Seeds Various types of seeds can be used in the seed mats, including grass, flower, vegetable (e. g., corn, peas, squash, radishes, and herbs such as chives, basil, marjoram, and dill), fruit (e. g. , tomatoes), and combinations thereof. Preferably, the seeds are grass seeds, which may be one variety of grass seed or mixtures of two or more varieties of grass seeds.

Suitable varieties of grass seed include, but are not limited to, tall fescue (Festuca arundinacea), creeping red fescue (Festuca rubra L. ssp rubra), chewings fescue

(Festuca rubra L. ssp. commutata), hard fescue (Festuca longifolia), sheep fescue (Festuca ovina), perennial ryegrass (Lolium prenne), annual ryegrass (Lolium multiflorum), Kentucky bluegrass (Poa pratensis), roughstalk bluegrass (Poa trivialis), canada bluegrass (Poa compressa), St Augustinegrass (Stenotaphrum secundatum), bahiagrass (Paspalum notatum), centipedegrass (Eremocloa ophiuroides), western wheatgrass (Agropyron smithii), crested wheatgrass (Agropyron desertorum), fairway wheatgrass (Agropyron cristatum), creeping bentgrass (Agrostis palustris), colonial bentgrass (Agrostis tenuis), velvet bentgrass (Agrostis canina), redtop (Agrostis alba) and other varieties and cultivars thereof.

The amount of seed per unit area depends upon various factors including the type of seeds (or blend of seeds) that is used. Typically, the amount of seed is about 0.5 to about 8.0 pounds of seed per 1000 square feet of area. Table 2 illustrates examples of preferred amounts for different types of grass seeds.

Table 2-Amounts of Grass Seeds

SpeciesIbs seed/I OOP ft2 100% Kentucky bluegrass about 1.5 to about 2.0 80% Kentucky bluegrass+20% perennial ryegrass about 3.0 to about 4.0 100% perennial ryegrassabout 4. 0 to about 5. 0 100% tail fescueabout 6. 0 to about 8. 0 100% creeping bentgrassabout 0. 5 to about 1. 0 Kentucky bluegrass+fine fescue and/or perennial about 2. 5 to 1. -, about 2.5 to about 3.0 rye

Water Insoluble Fibrous Layer The seed mat further comprises a water insoluble fibrous layer above the ground facing layer. The water insoluble fibrous layer preferably comprises cellulose fibers. The preferred composition and construction of the water insoluble fibrous layer depends on the method of production. Generally, air-laying or wet-laying methods are used to create the water insoluble fibrous layer. Several parameters describe the water insoluble fibrous layer, such as basis weight, density, porosity, and dry and wet tensile strength, regardless of the method of forming the layer.

The exact basis weight of the water insoluble fibrous layer depends on various factors, including the ratio of the amounts of refined to unrefined fibers and the method for making the water insoluble fibrous layer (e. g. , generally it is preferable that layers made by wet-laid methods have lower basis weights while layers made by air-laid methods can have higher basis weights). However, typically the water insoluble fibrous layer has a basis weight of up to about 220 grams per square meter, preferably about 20 to about 220 grams per square meter, more preferably about 50 to about 215 grams per square meter, most preferably about 160 grams per square meter.

The density of the water insoluble fibrous layer depends on various factors, including the basis weight of the water insoluble fibrous layer, the materials of construction, and the method of making the water insoluble fibrous layer. Preferred embodiments would minimize density limited by the properties of current materials and manufacturing methods. Fibrous structures with too high a density will not allow seedlings to grow through the mat. Preferred densities will be up to 100 kilograms per

cubic meter, more preferably about 5 kilograms per cubic meter (kg/m3) to about 100 3 3 kg/m3, still more preferably about 10 kg/m3 to about 70 kg/m3, most preferably about 30 3 kg/m.

The water insoluble fibrous layer may optionally be apertured, which allows for easier germination of the seeds and allows for even higher basis weights, densities, or both, than those exemplified above.

Air-laying methods of forming the fibrous layers have advantages of low density and low dry strength assuming no binders are used. This low density and strength are beneficial for germination. Preferred compositions utilize cellulosic fiber, either fully unrefined, such as wood fiber mulches, or in combination with various types of refined fibers, such as softwood and hardwood kraft pulps, sulfite pulps, cotton, cotton linters, and the like, or partially refined fibers such as chemithermomechanical pulps (CTMP).

The challenge with air-laying techniques is the inherently low tensile strength of the layer, and the resulting difficulty in handling during manufacture, shipping, and application. While in embodiments of this invention, sufficient integrity of the fibrous layer can be obtained by association with the seed binding substrate, other methods can be used to improve the robustness of the layer against various mechanical manipulations.

Optional adhesive materials may be applied, such as water soluble polymers well known in the art. Ideal solubility properties are described by similar measures as the ground facing layer. Adhesive materials may be sprayed on by common methods.

Another technique employs non-water soluble materials to help bind the fibrous layer. One example is fiber blends of cellulosic material with synthetic fibers. Examples of synthetic fibers are poly (ethylene) (PE), poly (propylene), or blends of these with poly (ethylene terephthatlate), and the like. The fibrous layer, after air-laying, is heat treated to melt the synthetic fiber and bind the cellulosic material. Synthetic fibers will have melting temperatures above at least 50 C, preferably about 70 C, and is limited at higher temperature only by practical constraints of processing and stability. Another example is the use of water insoluble adhesives, which can be sprayed on to bind the fibers. It is understood that in both examples practical limits exist to how much insoluble binding additives can be added. Too much binding agent will impede the growth and penetration of seedlings through the mat.

Wet-laying techniques employ a mixture of unrefined and refined cellulosic fibers wherein the refined fiber is at least 10 % of the total fiber furnish. This gives the wet-laid mat sufficient structural integrity to be transferred from the forming wire. The addition of chemical wet strength agents (e. g. , Kymene and others known in the art) or synthetic fibers followed by subsequent heating or application of an adhesive can be used to further increase the robustness of the mat to mechanical manipulations.

Optional Top Layer An optional top layer may be attached to the mat opposite the ground facing layer, e. g. , to help contain a weak fibrous layer. The purpose of the optional top layer is to provide protection in making and shipping to the fibrous layer (e. g. , by containing the fibrous layer and preventing the weakened mat from tearing during processing or to prevent the mat layers from undesirably bonding together when packaged together), or to retain any other loose material such as a variety of adjuvant materials described below.

The top layer can comprise a soluble film the same as, or similar in, composition and solubility properties as the ground facing substrate, or a paper substrate which readily disintegrates after wetting. In some cases a removable layer, such as a non-woven substrate, may be employed. This top layer performs like a carrier web during mechanical processing. During such processing the top layer becomes lightly mechanically bonded to the mat. The mechanical bonds are weak enough to enable easy removal of the top layer directly following processing or by a user prior to, during, or after placing the seed mat on the ground. However, the mechanical bonds are strong enough to attach the top layer to the mat to improve web handling and provide a removable spacing layer to allow easy separation of seed mats in their packaging, i. e. protect against the sticking of the ground facing layer from one seed mat to another, or separate layers in a roll. The top layer additionally aids the processing by ensuring that loose sections of the fibrous web do not jam mechanical processing equipment. It also carries the weakened mat through the process ensuring that tension in the line will not tear the mat.

Optional Adhesive Layers When the substrate is a soluble polymeric material, the preferred method of bonding the water insoluble fibrous layer to the ground facing layer is through solubilizing the surface of the ground facing layer. In this case, the ground facing layer is moistened and contacted with the insoluble fibrous layer. Adequate bonding results when the solubilized surface dries while in contact with the water insoluble fibrous layer. The strength of these bonds can be increased through further mechanical or pressure bonding including, but not limited to calendaring or lamination.

Optionally, adhesives may be employed to provide binding between the ground facing layer and the water insoluble fibrous layer, or between the water insoluble fibrous layer and the optional top layer, or both. Adhesives may be applied by, for example, spraying, brushing or rolling on to either or both layers before adhering. Preferred adhesives are water soluble materials, e. g. aqueous solutions of polysaccharides, aqueous solutions of synthetic polymers, or water insoluble liquid adhesives well known in the art.

It is understood that practical limits exist to how much water insoluble adhesive can be added. Too much adhesive may impede the growth and penetration of seedlings through the mat.

Optional Ingredients in the Seed Mats Optional ingredients in the ground facing layer include plasticizers such as glycerin, e. g. , in the substrate.

The water insoluble fibrous layer may further include various optional ingredients such as absorbent materials, fertilizers, macronutrients, micronutrients, pesticides, combinations thereof, and others.

Absorbent materials provide enhanced contact of moisture to seeds for germination, and provide higher local humidity for starting seedlings. The amounts of water absorbent materials needs to be limited to avoid creating occlusive gelled layers that inhibit the growth of seedlings. In some embodiments of the invention, aperturing or mechanical weakening of the water insoluble fibrous layer may still enable seedling growth when absorbent materials are present. A preferred absorbent material comprises grafted cellulose fibers described in U. S. Patents 5,049, 235; 5,160, 789; 5,443, 889; and

5,698, 074. Alternative absorbent materials include grafted starches for agricultural applications, such as HSPAN, crosslinked polysaccharides (e. g. , calcium alginate, guar gum crosslinked with borax, and alginic acid crosslinked with chitosan). Other absorbent materials include carboxymethyl cellulose, hydroxyalkyl cellulose, xanthan, pectin, gum arabic, guar gum, carageenan, agar, locust bean, and starch. Crosslinked synthetic polymers such as poly (acrylic acid), poly (acrylamide), and poly (vinyl alcohol) can also be used as absorbent materials. The optimal amount of absorbent material depends on several factors, most importantly on the absorbent capacity.

In one embodiment of the invention it is intended that the combination of materials used in the ground facing layer plus optional ingredients within the fibrous layer provide a thickened aqueous solution when the mat is dispersed in water to form a slurry.

Elevated viscosity provides for an even dispersion of seed and fibrous material in the slurry. In this embodiment it is envisioned the mat may be dispersed in water at a ratio of from about 1: 10 to about 1: 100, preferably from about 1: 15 to about 1: 50, most preferably from about 1: 20 to about 1: 30. Mixtures of this type typically have a viscosity in the aqueous portion of about 100 to 5000 centipoise. In this embodiment, a water thickening additive may be added to one or more layers of the seed mat, preferably the water insoluble fibrous layer.

Suitable fertilizers are known in the art, see for example WO 00/67549. Typically, fertilizers are present in amounts sufficient to provide about 10 to about 100 grams of fertilizer per square meter, more preferably about 30 to about 80. Fertilizers typically comprise sources of phosphorus, potassium, nitrogen, and combinations thereof.

Phosphorus sources include phosphorous pentoxide or derivatives thereof. Potassium sources include potassium salts such as potassium sulfate. Nitrogen sources include urea, nitrates, and ammonium compounds.

Suitable micronutrients include zinc, copper, boron, and seaweed extracts.

Suitable pesticides include herbicides, fungicides, insecticides, nematicides, rodenticides, and combinations thereof. Examples are disclosed in WO 00/11930 and U. S. Patent No. 6,164, 012.

Other optional ingredients that can be added to the water insoluble fibrous layer include vitamins, humic acid, sea kelp, sugars, amino acids, plant growth promoters and

hormones, pH regulators (such as lime and sulfur), salt binding agents (such as calcium sulfate), wetting agents (such as clay minerals like sodium bentonite), adsorbents, surfactants, polymer gels, gelatin, biological agents, dyes (such as green dye, which is preferred for grass seed mats), and combinations thereof.

Figure 1 shows a seed mat 100 according to one embodiment of this invention.

The seed mat 100 comprises a ground facing layer 101. The ground facing layer 101 comprises a water soluble substrate 102 and seeds 103. The seed mat 100 has an optional adhesive layer 104 between the ground facing layer 101 and a water insoluble fibrous layer 105. The seed mat 100 further comprises an optional top layer 106 above the water insoluble fibrous layer 105.

Mechanical Post Processing Aperturing and/or mechanical weakening or a combination of both may be applied to the mat or one or more layers of the mat to improve drape or mat lay down, enable survival of existing grass, and increase dispersion of the mat. In addition, mechanical weakening and aperturing both spread the material reducing the basis weight of the mat, thus reducing material costs.

Aperturing The size, shape, and frequency of apertures depend on various factors, including the type of seeds and the basis weight of the water insoluble fibrous layer. In general, the larger the apertures the better to allow ready penetration of germinating seed. The apertures can be, for example, slits about 1 to about 50 millimeters (mm) long.

Alternatively, the apertures can be ovoid holes, at least 1 mm in diameter or rectangular holes about I mm wide. The density of perforations can be up to about 50,000 per square meter, preferably about 100 to about 20,000, more preferably about 500 to about 1,000.

The apertures may be introduced through any method known in the art, but preferably through the selective aperturing method described in US 5,628, 097. In this method the preferred nonwoven is the solubilized polymeric material contacted with the insoluble fibrous layer. The two are bonded together and weakened by pressure bonding at a plurality of locations preferably in a heated atmosphere to dry the layers. The

substrate is then subjected to incremental stretching that causes the substrate to rupture at the plurality of weakened locations creating a plurality of apertures in the substrate coincident with the plurality of weakened locations.

Referring to FIG. 2 the aperturing process occurs through processing of the mat through units 205 and 206.205 is a calendaring arrangement preferably heated between 225 and 350 F. The calendaring arrangement is enlarged in FIG. 3 with 310 as a patterned roll and 312 representing a smooth surfaced anvil roll. The protuberances 316 are preferably truncated conical shapes which extend radially outwardly from surface 314 and which have elliptical distal end surfaces 317. It is believed that the aspect ratio (L/W) can be as low as 3 and as high as 20. This description of the protuberances does not seek to limit the invention from other suitable shapes or protuberance distribution patterns.

The material 212 passes through the nip between the rolls 310 and 312 and emerges with weakened locations 213 formed by the pressure bonding preferably near pressures of 700 psi. The weakened material 212 then passes through 206 the incremental stretching system. The incremental stretching system is enlarged in FIG. 4.

This system is composed of rolls 434 and 436. These rollers include a plurality of corresponding teeth 460 and 462 and grooves 461 and 463. The teeth 460 on roller 434 intermesh with or engage the grooves 463 on roller 436 while the teeth 462 on roller 436 intermesh with or engage the grooves 461 on roller 434. As the material 212 passes through the system it is subjected to cross machine direction tensioning causing the weakened areas 213 to rupture and create apertures 214. The incremental stretching can similarly be performed in the machine direction by unit 207 in FIG 2 also illustrated in FIG 5.

Mechanical Weakening The density of the insoluble fibrous web or entire structure can be further reduced through mechanical weakening. Mechanical weakening causes partial disentanglement of web fibers and/or introduces lines of weakness or discontinuity. This weakening process can be applied to portions of, or the entire web. Mechanical weakening can be applied to one layer alone or to more than one of the layers together (e. g., after joining). For

example, when applied to one layer alone, the substrate may be weakened before joining with the water insoluble fibrous layer, or alternatively, the water insoluble fibrous layer may be weakened before joining with the substrate. When applied to all layers together, the lines of weakness extend through the entire thickness of the mat.

Mechanical weakening can be performed by any methods known in the art, but preferably through ring rolling. Ring rolling is the passing of a material through a nip between two rolls. Ring rolling elongates the material thus reducing its density. When patterned or grooved rolls are used lines of discontinuity and weakness can be introduced into the substrate. Such lines enable break up of the material and may facilitate easy tear of the material similar to the affect seen with perforations. Material drape and dispersion are also improved through mechanical weakening.

Mechanical weakening is illustrated in FIG. 2 by units 206 and 207. Mechanical weakening can be performed in both the machine and cross machine directions or in either independently. Mechanical weakening can also be performed independently from an aperturing process. If the pattern roll in unit 205 is replaced by an additional smooth roll the layers are combined by lamination and no weakened area are created thus preventing the opening of apertures during incremental stretching through systems 206 and 207.

FIG. 5 represents mechanical weakening alone in the machine direction. Material 212 passes through rolls 534 and 536. The teeth 540 on roller 534 intermesh with or engage the grooves 543 on roller 536 while the teeth 542 on roller 536 intermesh with or engage the grooves 541 on roller 534. As the material 212 passes through the system it is subjected to machine direction tensioning creating weakened areas 544 that result in disentangling of the fibers of the fibrous layer and weakening of the ground facing layer.

This process can be performed on one layer or more than one layer together.

Methods of Making Seed Mats This invention further relates to methods for making the seed mats described above. Seed mats can be made by preparing the water insoluble fibrous layer and preparing the ground facing layer, and thereafter joining the layers. The layers may be joined, for example, by wetting one side of the water insoluble fibrous layer with

moisture and thereafter applying one side of the ground facing layer to the moistened side of the water insoluble fibrous layer. Alternatively, the layers may be joined by applying adhesive to one side of the water insoluble fibrous layer (e. g. , by spraying or coating by any convenient means) and thereafter applying one side of the ground facing layer to the adhesive.

The water insoluble fibrous layer can be prepared by wet-laid and air-laid methods that are readily available to one of ordinary skill in the art without undue experimentation.

The ground facing layer is typically prepared by spreading the substrate, optionally dissolved in a solvent, on a nonstick surface such as Teflon and sprinkling seeds on top.

The substrate is then dried. When the ground facing layer is obtained in the form of a film the seeds can be added following mat processing using the adhesives mentioned earlier or through solubilization of the surface of the ground facing layer.

The ground facing layer and fibrous layer can be subjected to aperturing and/or mechanical weakening procedures, as described above. These procedures can be performed on either of these layers separately or on the two combined. These procedures can also be performed on the mat with an added top layer, as described above, to lightly mechanically bond the top layer to the mat. These procedures can also be carried out on a mat having one or more optional adhesive layers, as described above.

Specific methods for preparing seed mats are described in detail in the examples herein. In a preferred embodiment of the invention, a seed mat is prepared from a commercially available polymeric film and a binderless wet-laid paper substrate. A preferred polyvinyl alcohol polymer film is MONO-SOL'" M-8630 commercially available from Chris Craft Industrial Products, Inc. , Gary, Indiana, USA. The wet-laid fibrous layer preferably contains by absorbent structure weight, 5% to 75% hardwood fibers, 5% to 75% CTMP fibers, and 25% to 85% softwood fibers. A web of High Elongation Carded polypropylene (HEC PP) is optionally used as a top layer. When used, the HEC PP lies below the fibrous layer that is sandwiched against the HEC PP by the polymeric film. Figure 2 shows this process. 201,202, and 203 are unwinds containing the polyvinyl alcohol film, the fibrous layer, and the HEC PP nonwoven respectively. When the mat will be apertured and/or mechanically weakened, the seeds are applied to the mat thereafter.

In a preferred embodiment of the invention, the water insoluble fibrous layer and ground facing layer are joined by moistening one side of the water insoluble fibrous layer.

The moisture is applied to the absorbent fibrous web with a spray system (204). The fibrous layer is immediately contacted with the soluble polymeric layer. The moisture causes the polymeric layer to solubilize as the layers are pressure treated between a heated patterned calendar roll and a smooth anvil roll both part of unit 205. Preferably, the rolls are heated to 320 F and 700 psig of pressure is applied between the rolls. The applied pressure mechanically bonds the solubilized layer to the fibrous layer while the applied heat flashes off excessive water and dries the layers. In addition the patterned roll creates a plurality of weakened areas (213).

The mat is then subjected to mechanical weakening first through cross directional ring rolls (206) and secondly through a set of machine direction ring rolls (207) causing the weakened areas to open creating apertures. Seeds are added to the completed mat by solubilizing the exposed side of the film with a second spray system (208), dropping on seeds with unit 209, and then drying the film with the seeds attached. During drying the mat can optionally be fed through a nip in lamination rolls 210 to ensure the seeds are attached. At this time the HEC PP top layer can be removed or left with the final web that is wound onto winder 211.

In an alternative embodiment of the invention, this process is repeated except that the patterned calendar roll is replaced with a second smooth roll resulting in lamination.

Mechanical weakening in either or both the cross machine and machine directions follow this lamination procedure. The resulting product is not apertured, but weakened to enable dispersion.

In an alternative embodiment of the invention, this process is repeated except that the pre-weakened water insoluble fibrous layer is applied to the ground facing layer and optionally further post mechanically weakened.

Methods of Using Seed Mats This invention further relates to methods for growing plants using the seed mats described above. The method comprises:

i. placing a seed mat described above on ground, wherein the ground facing layer faces towards the ground, and ii. watering the seed mat.

This method offers the advantage that when the seed mat is watered in step ii, the water soluble polymer in the substrate of the ground facing layer dissolves, and the seeds fall to the ground. This ensures direct contact of the seeds with the ground, thereby preventing the problem of seeds germinating in the mat and dying if there were a gap between the roots of the germinating seed in the seed mat and the ground.

The method optionally further comprises forming the seed mat to a desired size, shape, or both, prior to step i. The seed mats described above are flexible enough that a consumer can conveniently cut (e. g. , with scissors or a knife) or tear (e. g. , by hand) the seed mats to the desired size and shape.

The method optionally further comprises the removal of the top layer prior to, during, or after step i. If removable, this layer is lightly mechanically bonded to the seed mat and can be removed by hand.

In another embodiment of the invention, the mat can be mixed with water to create a slurry for application to irregular small areas on the ground. The optimal spreading rate of solids is similar to the ranges of basis weight described previously.

Typically, the slurry is applied to a depth of about 0.25 inch on the ground.

Kits This invention further relates to kits that can be used by a consumer to install and use the seed mats according to this invention. The kit comprises at least one seed mat described above and information, instructions, or both, for using the kit. The information, instructions, or both, typically comprise words, pictures, videotapes, DVDs, or combinations thereof describing how to install and/or use the seed mat, how frequently to water the seed mat after installation, etc. Preferably, the seed mat is watered daily until germinated and grown to an average height of about 2 inches, then as needed for sustained vigor thereafter.

EXAMPLES

These examples are intended to illustrate the invention to one of ordinary skill in the art and should not be interpreted as limiting the scope of the invention set forth in the claims.

Reference Example 1-Wet Laid Preparation of a Water Insoluble Fibrous Layer A slurry of wood fiber mulch and NSK is prepared by repulping wood fiber mulch and NSK-dry lap in a blender on low speed for one minute. A deckle box is fitted with a forming wire (Albany International-Appelton Wire Division, Appleton, Wis.; handsheet style/mesh 78-S) and is filled with water. The slurry is added and the water is drained by suction. The wet mat thus formed is transferred to a drying fabric (Albany Intemational-Appelton Wire Division, Appelton, Wis.; handsheet style/mesh 36-C) by passage over a vacuum slit on low setting. The drying fabric is then passed over the vacuum slit two additional times on high setting and then another fabric is placed on top of the wet paper sheet. The sandwich is then passed through a drum dryer at 230 F until the mat is dry.

Reference Example 2-Air-Laid Preparation of a Water Insoluble Fibrous Layer Dry wood fiber mulch is passed through a mixing chamber consisting of two blades rotating at high speeds. The mass remains in the chamber until it is sufficiently broken up into individual fibers that can pass through a wire mesh screen. They are then pulled by suction through au-shaped PVC tube and collected on a screen that is approximately six inches in diameter.

Reference Example 3-Air-Laid Water Insoluble Fibrous Layer with Synthetic Fiber Binder Reference example 2 is repeated except that 2% to 5% by weight of the fiber furnish is a poly (ethylene) - poly (ethylene terephthalate) bicomponent fiber. The mat is then heated in a convection oven at 140 C to 145 C for 5 to 10 minutes.

Reference Example 4-Preparation of a Foam Substrate Hot water (100 milliliters) is placed in a commercial blender and 12.0 g of poly (vinyl alcohol) (88% hydrolyzed, nominal molecular weight of 25, 000) is added.

This is mixed thoroughly until the poly (vinyl alcohol) has completely dissolved.

Glycerin (6.0 g) is added and the solution is mixed on a high setting for 15 to 20 minutes.

The resulting foam is divided into two equal portions onto 12"X15"Teflon sheets and then spread out into thin layers of uniform thickness. The recommended weight of grass seeds per unit area is applied to the top of the foam. The foam layer is then dried in a convection oven at 65 to 70 C for. 30 to 45 minutes. After cooling to room temperature, the dried layer of foam and grass seed is peeled from the Teflon sheet.

Example 1-Seed Mat Preparation A seed mat is prepared by moistening one side of a water insoluble fibrous layer prepared by the method of Reference Example 1. The product of Reference Example 4 is applied to the moistened side of the water insoluble fibrous layer. The mat is allowed to dry.

Example 2-Seed Mat Preparation A seed mat is prepared by moistening one side of a water insoluble fibrous layer prepared by the method of Reference Example 2. The product of Reference Example 4 is applied to the moistened side of the water insoluble fibrous layer. The mat is allowed to dry.

Example 3-Seed Mat Preparation A seed mat is prepared by moistening one side of a water insoluble fibrous layer prepared by the method of Reference Example 3. The product of Reference Example 4 is applied to the moistened side of the water insoluble fibrous layer. The mat is allowed to dry.

Reference Example 4-Seed Mat Preparation

Seed mats are prepared from a commercially available film and a binderless wetlaid paper substrate. The polyvinyl alcohol polymer film is MONO-SOL M-8630 commercially available from Chris Craft Industrial Products, Inc. , Gary, Indiana, USA.

The wet laid fibrous layer contains by absorbent structure weight, 5% to 75% hardwood fibers, 5% to 75% CTMP fibers, and 25% to 85% softwood fibers. A web of High Elongation Carded polypropylene (HEC PP) is used as a top layer. The HEC PP lies below the fibrous layer that is sandwiched against the HEC PP by the polymeric film.

The water insoluble fibrous layer and ground facing layer are joined by moistening one side of the water insoluble fibrous layer. Solubilization occurs when the water soluble web contacts moisture. The moisture is applied to the absorbent fibrous web with a spray system. The fibrous layer is immediately contacted with the soluble polymeric layer.

The moisture causes the polymeric layer to solubilize as the layers are pressure treated between a heated patterned calendar roll and a smooth anvil roll. The rolls are heated to 320 F, and 700 psig of pressure is applied between the rolls. The applied pressure mechanically bonds the solubilized layer to the fibrous layer while the applied heat flashes off excessive water and dries the layers. In addition the patterned roll creates a plurality of weakened areas.

The mat is then subjected to mechanical weakening through cross directional ring rolls causing the weakened areas to open creating apertures. Seeds are added to the completed mat by solubilizing the exposed side of the film, dropping on seeds, and then drying the film with the seeds attached.

Example 4-Seed Mat Preparation Seed mats are prepared according to the method of Reference Example 4. The seed mats have water insoluble fibrous layers with the compositions in Table 3, below.

Table 3-Water Insoluble Fibrous Layer Compositions

Sample Hardwood Fibers (wt CTMP Fibers (wt %) Softwood Fibers (wt %) %) 4A 5 10 85 4B 10 15 75

4C 25 15 60 4D 45 5 50 4E 60 5 35 4F 70 5 25

Reference Example 5-Seed Mat Preparation Reference Example 4 is repeated except the patterned calendar roll is replaced with a second smooth roll resulting in lamination. Mechanical weakening in either or both the cross machine and machine directions follow this lamination procedure.

Example 5-Seed Mat Preparation Seed mats are prepared according to the method of Reference Example 5. The seed mats have water insoluble fibrous layer compositions shown in Table 4.

Table 4-Water Insoluble Fibrous Layer Compositions

Sample Hardwood Fibers (wt CTMP Fibers (wt %) Softwood Fibers (wt %) %) 5A 5 10 85 5B 10 15 75 5C 25 15 60 5D 45 5 50 5E 60 5 35 5F 70 5 25 Reference Example 6-Seed Mat Preparation Reference Example 5 is repeated, except that a pre-weakened water insoluble fibrous layer is applied to the ground facing layer and further post mechanical weakening is optional.

Example 6-Seed Mat Preparation

Seed mats are prepared according to the method of Reference Example 6. The seed mats have water insoluble fibrous layer compositions shown in Table 5.

Table 5-Seed Mat Properties

Sample Hardwood CTMP Fibers Softwood Post Fibers (wt %) (wt %) Fibers (wt %) Mechanical Weakening? 6A 5 10 85 yes 6B 10 15 75 no 6C 25 15 60 yes 6D 45 5 50 no 6E 60 5 35 yes Reference Example 7-Seed Mat Preparation Reference Example 4 is repeated, except that the HEC PP top layer is not added.

Example 7-Seed Mat Preparation Seed mats are prepared according to the method of Reference Example 7. The seed mats have water insoluble fibrous layers with the compositions in Table 6, below.

Table 6-Water Insoluble Fibrous Layer Compositions

Sample Hardwood Fibers (wt CTMP Fibers (wt %) Softwood Fibers (wt %) %) 7A 5 10 85 7B 10 15 75 7C 25 15 60 7D 45 5 50 7E 60 5 35 7F 70 5 25 Reference Example 8-Rate ofDispersibility

Rate of Dispersibility is determined according to a modified Japanese Industrial Standard (JIS) test P4501-1993. An 800 milliliter cylindrical graduated Griffin beaker (6.3 centimeters (cm) by 15.2 cm, such as VWR Scientific Products, Catalogue &num; 13910- 267,1997/1998) with 300 milliliters deionized (DI) water at 23 degrees C is equipped with a 35 millimeter diameter magnetic starhead stir disk (12 millimeter maximum thickness, starhead protrusions extending from both sides, such as available from VWR Scientific Products, catalogue &num; 58948-568,97/98, or equivalent), and placed on a magnetic stir plate set to rotate the stir disk at 600 revolutions per minute (rpm).

A 0.38 gram (g) sample of absorbent product is pre-conditioned at 20 degrees C (+/-5 degrees C) and 65% Relative Humidity (+/-5%) until equilibrium. In the event that the product to be tested is less than 0.38 g, then multiple products or fractions of multiple products are used to increase the total weight to 0. 38 g. In the event that the product to be tested is larger than 0.38 g, then product size is reduced such that a 0.38 g portion of the product is tested. The product sample tested according to the present test

2 should have a total exterior surface area of at least 20 cm2. If the total exterior surface 2 area of a product sample that has been reduced to 0. 38 g is less than 20 cm2, then a larger sample of the product should be used for the present test such that the total surface area is 2 20 cm2.

The sample is dropped into the center of the vortex caused by the stirring, which causes stir bar rotational rate to decrease, and a stopwatch is simultaneously started. The time in seconds for the stir bar to increase in rotational rate until it reaches 540 rpm is recorded as the Rate of Dispersibility. If addition of the sample to the beaker causes the stir disk to be moved off center from its natural axis of rotation or if it ceases rotating, the test run is invalid and should be repeated with a new sample of product.

Claims

We claim: 1. A seed mat comprising: a. a ground facing layer comprising a water soluble substrate and seeds; b. optionally an adhesive layer positioned between at least a portion of layers a and c ; c. a water insoluble fibrous layer above the ground facing layer; and d. optionally a top layer above the water insoluble fibrous layer.
2. The mat of claim 1, wherein the substrate is selected from the group consisting of a film and a foam.
3. The mat of claim 2, wherein the substrate is a film.
4. The mat of claim 2, wherein the substrate comprises a water soluble polymer selected from the group consisting of naturally occurring polymers, synthetic water soluble polymers, and combinations thereof.
5. The mat of claim 4, wherein the naturally occuring polymer is a polysaccharide.
6. The mat of claim 4, wherein the synthetic water soluble polymer is selected from the group consisting of poly (vinyl alcohols), poly (ethyleneglycols), poly (ethylene oxides), poly (acrylamides), poly (N-alkyl or N, N-dialkyl acrylamides), poly (acrylic acids), poly (vinyl pyrolidones), poly (hydroxyalkyl acrylates), chemically modified starches, and combinations thereof.
7. The mat of claim 2, wherein the substrate comprises poly (vinyl alcohols).
8. The mat of claim 7, wherein the substrate further comprises glycerin.

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9. The mat of claim 1, wherein the substrate dissolves sufficiently that seeds no longer adhere to the mat after the mat is watered.
10. The mat of claim 1, wherein the seeds are selected from the group consisting of grass seeds, flower seeds, vegetable seeds, fruit seeds, and combinations thereof.
11. The mat of claim 10, wherein the grass seeds are selected from the group consisting of tall fescue (Festuca arundinacea), creeping red fescue (Festuca rubra L. ssp rubra), chewings fescue (Festuca rubra L. ssp. commutata), hard fescue (Festuca

longifolia), sheep fescue (Festuca ovina), perennial ryegrass (Lolium prenne), annual ryegrass (Lolium multiflorum), Kentucky bluegrass (Poa pratensis), roughstalk bluegrass (Poa trivialis), canada bluegrass (Poa compressa), St Augustinegrass (Stenotaphrum secundatum), bahiagrass (Paspalum notatum), centipedegrass (Eremocloa ophiurides), western wheatgrass (Agropyron smithii), crested wheatgrass (Agropyron desertorum), fairway wheatgrass (Agropyron cristatum), creeping bentgrass (Agrostis palustris), colonial bentgrass (Agrostis tenuis), velvet bentgrass (Agrostis canina), redtop (Agrostis alba), and cultivars thereof.
12. The mat of claim 1, wherein layer c is prepared by a wet-laid method and wherein layer c comprises cellulose fibers, wherein at least about 10% of the cellulose fibers are refined cellulose fibers.
13. The mat of claim 1, wherein layer c is prepared by an air-laid method and layer c comprises cellulose fibers and synthetic fibers.
14. The mat of claim 1, wherein layer c has a basis weight of up to about 220 grams per square meter and a density of up to about 100 kilograms per cubic meter.
15. The mat of claim 1, wherein layer c further comprises one or more optional ingredients selected from the group consisting of : absorbent materials, fertilizers, macronutrients, micronutrients, pesticides, vitamins, humic acid, sea kelp, sugars, amino acids, plant growth promoters and hormones, pH regulators, salt binding agents,

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adsorbents, wetting agents, gelatin, surfactants, polymer gels, biological agents, dyes, and combinations thereof.
16. The mat of claim 1, wherein one or more of layers a, b, c, and d is aperatured.
17. The mat of claim 1, wherein layer d is removable.
18. The mat of claim 17, wherein layer d is lightly mechanically bonded to layer c.
19. The mat of claim 1, wherein the mat further comprises a water thickening additive such that viscosity of a slurry comprising the mat and water in a ratio of about 1: 10 to about 1: 100 has a viscosity of about 100 centipoise to about 5000 centipoise.
20. A slurry comprising: a seed mat according to claim 1 and water in a ratio of about 1: 10 to about 1: 100.
21. A kit comprising: a) a seed mat according to claim 1, and b) information, instructions, or both describing how to install and/or use and/or water the seed mat.
22. A process for preparing the seed mat of claim 1 comprising: 1) joining layers a and c.
23. The process of claim 22, wherein step 1) is carried out by: i) solubilizing layer a, and ii) contacting the product of step i) with layer c.
24. The process of claim 23, wherein the seed mat is subjected to further mechanical binding after step i).
25. The process of claim 22, wherein the seeds are added to layer a after step 1).

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26. The process of claim 22, wherein layer a is mechanically weakened prior to combining with layer c.
27. The process of claim 22, wherein layer c is mechanically weakened prior to combining with layer a.
28. The process of claim 22, wherein the mat is mechanically weakened wherein at least layer c comprises a plurality of discrete sections separated by lines of weakness, wherein said lines of weakness are created by partially disentangling at least a portion of the fibers in layer c.
29. The process of claim 28, wherein said lines of weakness extend through the entire thickness of the mat.
30. The process of any of claims 26-29, wherein the mechanically weakening is carried out by ring rolling.
31. A process for aperaturing a seed mat comprising: 1) preparing a seed mat according to claim 1, 2) weakening the product of step 1) at a plurality of discrete sites, and 3) subjecting the product of step 2) to incremental stretching, thereby causing the mat to rupture at the plurality of discrete sites and creating a plurality of apertures coincident with the plurality of discrete sites.
32. The process of claim 31, wherein the incremental stretching comprises feeding the seed mat through a nip formed by a pair of incremental stretching rollers.
33. The process of claim 32, wherein one of said pair of incremental stretching rollers comprises a plurality of teeth and another of said pair of incremental stretching rolles comprises a plurality of grooves.

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34. A method for growing plants comprising: i) placing a seed mat according to claim 1 on ground, wherein the ground facing layer faces towards the ground, and ii) watering the seed mat.
35. The method of claim 34, further comprising forming the mat to a desired size, shape, or both, prior to step i).
36. The method of claim 34, wherein the seed mat comprises: a. a ground facing layer comprising a water soluble substrate and seeds, b. optionally an adhesive layer positioned between at least a portion of layers a and c, c. a water insoluble fibrous layer above the ground facing layerd and d. a top layer above the water insoluble fibrous layer; and wherein the method further comprises removing layer d prior to, during, or after step i).
37. A method for growing plants comprising: i. preparing a slurry comprising a seed mat according to claim 1 and water at a ratio of about 1: 10 to about 1: 100, and ii. spreading the slurry on ground.
38. The method of claim 37, wherein the slurry is spread on the ground to a depth of about Y4 inch.